// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
/*
* Common eBPF ELF object loading operations.
*
* Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
* Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
* Copyright (C) 2015 Huawei Inc.
* Copyright (C) 2017 Nicira, Inc.
* Copyright (C) 2019 Isovalent, Inc.
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <libgen.h>
#include <inttypes.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <endian.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
#include <asm/unistd.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/filter.h>
#include <linux/limits.h>
#include <linux/perf_event.h>
#include <linux/bpf_perf_event.h>
#include <linux/ring_buffer.h>
#include <sys/epoll.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h>
#include <sys/utsname.h>
#include <sys/resource.h>
#include <libelf.h>
#include <gelf.h>
#include <zlib.h>
#include "libbpf.h"
#include "bpf.h"
#include "btf.h"
#include "str_error.h"
#include "libbpf_internal.h"
#include "hashmap.h"
#include "bpf_gen_internal.h"
#include "zip.h"
#ifndef BPF_FS_MAGIC
#define BPF_FS_MAGIC 0xcafe4a11
#endif
#define BPF_FS_DEFAULT_PATH "/sys/fs/bpf"
#define BPF_INSN_SZ (sizeof(struct bpf_insn))
/* vsprintf() in __base_pr() uses nonliteral format string. It may break
* compilation if user enables corresponding warning. Disable it explicitly.
*/
#pragma GCC diagnostic ignored "-Wformat-nonliteral"
#define __printf(a, b) __attribute__((format(printf, a, b)))
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
static int map_set_def_max_entries(struct bpf_map *map);
static const char * const attach_type_name[] = {
[BPF_CGROUP_INET_INGRESS] = "cgroup_inet_ingress",
[BPF_CGROUP_INET_EGRESS] = "cgroup_inet_egress",
[BPF_CGROUP_INET_SOCK_CREATE] = "cgroup_inet_sock_create",
[BPF_CGROUP_INET_SOCK_RELEASE] = "cgroup_inet_sock_release",
[BPF_CGROUP_SOCK_OPS] = "cgroup_sock_ops",
[BPF_CGROUP_DEVICE] = "cgroup_device",
[BPF_CGROUP_INET4_BIND] = "cgroup_inet4_bind",
[BPF_CGROUP_INET6_BIND] = "cgroup_inet6_bind",
[BPF_CGROUP_INET4_CONNECT] = "cgroup_inet4_connect",
[BPF_CGROUP_INET6_CONNECT] = "cgroup_inet6_connect",
[BPF_CGROUP_UNIX_CONNECT] = "cgroup_unix_connect",
[BPF_CGROUP_INET4_POST_BIND] = "cgroup_inet4_post_bind",
[BPF_CGROUP_INET6_POST_BIND] = "cgroup_inet6_post_bind",
[BPF_CGROUP_INET4_GETPEERNAME] = "cgroup_inet4_getpeername",
[BPF_CGROUP_INET6_GETPEERNAME] = "cgroup_inet6_getpeername",
[BPF_CGROUP_UNIX_GETPEERNAME] = "cgroup_unix_getpeername",
[BPF_CGROUP_INET4_GETSOCKNAME] = "cgroup_inet4_getsockname",
[BPF_CGROUP_INET6_GETSOCKNAME] = "cgroup_inet6_getsockname",
[BPF_CGROUP_UNIX_GETSOCKNAME] = "cgroup_unix_getsockname",
[BPF_CGROUP_UDP4_SENDMSG] = "cgroup_udp4_sendmsg",
[BPF_CGROUP_UDP6_SENDMSG] = "cgroup_udp6_sendmsg",
[BPF_CGROUP_UNIX_SENDMSG] = "cgroup_unix_sendmsg",
[BPF_CGROUP_SYSCTL] = "cgroup_sysctl",
[BPF_CGROUP_UDP4_RECVMSG] = "cgroup_udp4_recvmsg",
[BPF_CGROUP_UDP6_RECVMSG] = "cgroup_udp6_recvmsg",
[BPF_CGROUP_UNIX_RECVMSG] = "cgroup_unix_recvmsg",
[BPF_CGROUP_GETSOCKOPT] = "cgroup_getsockopt",
[BPF_CGROUP_SETSOCKOPT] = "cgroup_setsockopt",
[BPF_SK_SKB_STREAM_PARSER] = "sk_skb_stream_parser",
[BPF_SK_SKB_STREAM_VERDICT] = "sk_skb_stream_verdict",
[BPF_SK_SKB_VERDICT] = "sk_skb_verdict",
[BPF_SK_MSG_VERDICT] = "sk_msg_verdict",
[BPF_LIRC_MODE2] = "lirc_mode2",
[BPF_FLOW_DISSECTOR] = "flow_dissector",
[BPF_TRACE_RAW_TP] = "trace_raw_tp",
[BPF_TRACE_FENTRY] = "trace_fentry",
[BPF_TRACE_FEXIT] = "trace_fexit",
[BPF_MODIFY_RETURN] = "modify_return",
[BPF_LSM_MAC] = "lsm_mac",
[BPF_LSM_CGROUP] = "lsm_cgroup",
[BPF_SK_LOOKUP] = "sk_lookup",
[BPF_TRACE_ITER] = "trace_iter",
[BPF_XDP_DEVMAP] = "xdp_devmap",
[BPF_XDP_CPUMAP] = "xdp_cpumap",
[BPF_XDP] = "xdp",
[BPF_SK_REUSEPORT_SELECT] = "sk_reuseport_select",
[BPF_SK_REUSEPORT_SELECT_OR_MIGRATE] = "sk_reuseport_select_or_migrate",
[BPF_PERF_EVENT] = "perf_event",
[BPF_TRACE_KPROBE_MULTI] = "trace_kprobe_multi",
[BPF_STRUCT_OPS] = "struct_ops",
[BPF_NETFILTER] = "netfilter",
[BPF_TCX_INGRESS] = "tcx_ingress",
[BPF_TCX_EGRESS] = "tcx_egress",
[BPF_TRACE_UPROBE_MULTI] = "trace_uprobe_multi",
[BPF_NETKIT_PRIMARY] = "netkit_primary",
[BPF_NETKIT_PEER] = "netkit_peer",
[BPF_TRACE_KPROBE_SESSION] = "trace_kprobe_session",
[BPF_TRACE_UPROBE_SESSION] = "trace_uprobe_session",
};
static const char * const link_type_name[] = {
[BPF_LINK_TYPE_UNSPEC] = "unspec",
[BPF_LINK_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_LINK_TYPE_TRACING] = "tracing",
[BPF_LINK_TYPE_CGROUP] = "cgroup",
[BPF_LINK_TYPE_ITER] = "iter",
[BPF_LINK_TYPE_NETNS] = "netns",
[BPF_LINK_TYPE_XDP] = "xdp",
[BPF_LINK_TYPE_PERF_EVENT] = "perf_event",
[BPF_LINK_TYPE_KPROBE_MULTI] = "kprobe_multi",
[BPF_LINK_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_LINK_TYPE_NETFILTER] = "netfilter",
[BPF_LINK_TYPE_TCX] = "tcx",
[BPF_LINK_TYPE_UPROBE_MULTI] = "uprobe_multi",
[BPF_LINK_TYPE_NETKIT] = "netkit",
[BPF_LINK_TYPE_SOCKMAP] = "sockmap",
};
static const char * const map_type_name[] = {
[BPF_MAP_TYPE_UNSPEC] = "unspec",
[BPF_MAP_TYPE_HASH] = "hash",
[BPF_MAP_TYPE_ARRAY] = "array",
[BPF_MAP_TYPE_PROG_ARRAY] = "prog_array",
[BPF_MAP_TYPE_PERF_EVENT_ARRAY] = "perf_event_array",
[BPF_MAP_TYPE_PERCPU_HASH] = "percpu_hash",
[BPF_MAP_TYPE_PERCPU_ARRAY] = "percpu_array",
[BPF_MAP_TYPE_STACK_TRACE] = "stack_trace",
[BPF_MAP_TYPE_CGROUP_ARRAY] = "cgroup_array",
[BPF_MAP_TYPE_LRU_HASH] = "lru_hash",
[BPF_MAP_TYPE_LRU_PERCPU_HASH] = "lru_percpu_hash",
[BPF_MAP_TYPE_LPM_TRIE] = "lpm_trie",
[BPF_MAP_TYPE_ARRAY_OF_MAPS] = "array_of_maps",
[BPF_MAP_TYPE_HASH_OF_MAPS] = "hash_of_maps",
[BPF_MAP_TYPE_DEVMAP] = "devmap",
[BPF_MAP_TYPE_DEVMAP_HASH] = "devmap_hash",
[BPF_MAP_TYPE_SOCKMAP] = "sockmap",
[BPF_MAP_TYPE_CPUMAP] = "cpumap",
[BPF_MAP_TYPE_XSKMAP] = "xskmap",
[BPF_MAP_TYPE_SOCKHASH] = "sockhash",
[BPF_MAP_TYPE_CGROUP_STORAGE] = "cgroup_storage",
[BPF_MAP_TYPE_REUSEPORT_SOCKARRAY] = "reuseport_sockarray",
[BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE] = "percpu_cgroup_storage",
[BPF_MAP_TYPE_QUEUE] = "queue",
[BPF_MAP_TYPE_STACK] = "stack",
[BPF_MAP_TYPE_SK_STORAGE] = "sk_storage",
[BPF_MAP_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_MAP_TYPE_RINGBUF] = "ringbuf",
[BPF_MAP_TYPE_INODE_STORAGE] = "inode_storage",
[BPF_MAP_TYPE_TASK_STORAGE] = "task_storage",
[BPF_MAP_TYPE_BLOOM_FILTER] = "bloom_filter",
[BPF_MAP_TYPE_USER_RINGBUF] = "user_ringbuf",
[BPF_MAP_TYPE_CGRP_STORAGE] = "cgrp_storage",
[BPF_MAP_TYPE_ARENA] = "arena",
};
static const char * const prog_type_name[] = {
[BPF_PROG_TYPE_UNSPEC] = "unspec",
[BPF_PROG_TYPE_SOCKET_FILTER] = "socket_filter",
[BPF_PROG_TYPE_KPROBE] = "kprobe",
[BPF_PROG_TYPE_SCHED_CLS] = "sched_cls",
[BPF_PROG_TYPE_SCHED_ACT] = "sched_act",
[BPF_PROG_TYPE_TRACEPOINT] = "tracepoint",
[BPF_PROG_TYPE_XDP] = "xdp",
[BPF_PROG_TYPE_PERF_EVENT] = "perf_event",
[BPF_PROG_TYPE_CGROUP_SKB] = "cgroup_skb",
[BPF_PROG_TYPE_CGROUP_SOCK] = "cgroup_sock",
[BPF_PROG_TYPE_LWT_IN] = "lwt_in",
[BPF_PROG_TYPE_LWT_OUT] = "lwt_out",
[BPF_PROG_TYPE_LWT_XMIT] = "lwt_xmit",
[BPF_PROG_TYPE_SOCK_OPS] = "sock_ops",
[BPF_PROG_TYPE_SK_SKB] = "sk_skb",
[BPF_PROG_TYPE_CGROUP_DEVICE] = "cgroup_device",
[BPF_PROG_TYPE_SK_MSG] = "sk_msg",
[BPF_PROG_TYPE_RAW_TRACEPOINT] = "raw_tracepoint",
[BPF_PROG_TYPE_CGROUP_SOCK_ADDR] = "cgroup_sock_addr",
[BPF_PROG_TYPE_LWT_SEG6LOCAL] = "lwt_seg6local",
[BPF_PROG_TYPE_LIRC_MODE2] = "lirc_mode2",
[BPF_PROG_TYPE_SK_REUSEPORT] = "sk_reuseport",
[BPF_PROG_TYPE_FLOW_DISSECTOR] = "flow_dissector",
[BPF_PROG_TYPE_CGROUP_SYSCTL] = "cgroup_sysctl",
[BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE] = "raw_tracepoint_writable",
[BPF_PROG_TYPE_CGROUP_SOCKOPT] = "cgroup_sockopt",
[BPF_PROG_TYPE_TRACING] = "tracing",
[BPF_PROG_TYPE_STRUCT_OPS] = "struct_ops",
[BPF_PROG_TYPE_EXT] = "ext",
[BPF_PROG_TYPE_LSM] = "lsm",
[BPF_PROG_TYPE_SK_LOOKUP] = "sk_lookup",
[BPF_PROG_TYPE_SYSCALL] = "syscall",
[BPF_PROG_TYPE_NETFILTER] = "netfilter",
};
static int __base_pr(enum libbpf_print_level level, const char *format,
va_list args)
{
const char *env_var = "LIBBPF_LOG_LEVEL";
static enum libbpf_print_level min_level = LIBBPF_INFO;
static bool initialized;
if (!initialized) {
char *verbosity;
initialized = true;
verbosity = getenv(env_var);
if (verbosity) {
if (strcasecmp(verbosity, "warn") == 0)
min_level = LIBBPF_WARN;
else if (strcasecmp(verbosity, "debug") == 0)
min_level = LIBBPF_DEBUG;
else if (strcasecmp(verbosity, "info") == 0)
min_level = LIBBPF_INFO;
else
fprintf(stderr, "libbpf: unrecognized '%s' envvar value: '%s', should be one of 'warn', 'debug', or 'info'.\n",
env_var, verbosity);
}
}
/* if too verbose, skip logging */
if (level > min_level)
return 0;
return vfprintf(stderr, format, args);
}
static libbpf_print_fn_t __libbpf_pr = __base_pr;
libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
{
libbpf_print_fn_t old_print_fn;
old_print_fn = __atomic_exchange_n(&__libbpf_pr, fn, __ATOMIC_RELAXED);
return old_print_fn;
}
__printf(2, 3)
void libbpf_print(enum libbpf_print_level level, const char *format, ...)
{
va_list args;
int old_errno;
libbpf_print_fn_t print_fn;
print_fn = __atomic_load_n(&__libbpf_pr, __ATOMIC_RELAXED);
if (!print_fn)
return;
old_errno = errno;
va_start(args, format);
__libbpf_pr(level, format, args);
va_end(args);
errno = old_errno;
}
static void pr_perm_msg(int err)
{
struct rlimit limit;
char buf[100];
if (err != -EPERM || geteuid() != 0)
return;
err = getrlimit(RLIMIT_MEMLOCK, &limit);
if (err)
return;
if (limit.rlim_cur == RLIM_INFINITY)
return;
if (limit.rlim_cur < 1024)
snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
else if (limit.rlim_cur < 1024*1024)
snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
else
snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
buf);
}
#define STRERR_BUFSIZE 128
/* Copied from tools/perf/util/util.h */
#ifndef zfree
# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
#endif
#ifndef zclose
# define zclose(fd) ({ \
int ___err = 0; \
if ((fd) >= 0) \
___err = close((fd)); \
fd = -1; \
___err; })
#endif
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
}
int libbpf_set_strict_mode(enum libbpf_strict_mode mode)
{
/* as of v1.0 libbpf_set_strict_mode() is a no-op */
return 0;
}
__u32 libbpf_major_version(void)
{
return LIBBPF_MAJOR_VERSION;
}
__u32 libbpf_minor_version(void)
{
return LIBBPF_MINOR_VERSION;
}
const char *libbpf_version_string(void)
{
#define __S(X) #X
#define _S(X) __S(X)
return "v" _S(LIBBPF_MAJOR_VERSION) "." _S(LIBBPF_MINOR_VERSION);
#undef _S
#undef __S
}
enum reloc_type {
RELO_LD64,
RELO_CALL,
RELO_DATA,
RELO_EXTERN_LD64,
RELO_EXTERN_CALL,
RELO_SUBPROG_ADDR,
RELO_CORE,
};
struct reloc_desc {
enum reloc_type type;
int insn_idx;
union {
const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
struct {
int map_idx;
int sym_off;
int ext_idx;
};
};
};
/* stored as sec_def->cookie for all libbpf-supported SEC()s */
enum sec_def_flags {
SEC_NONE = 0,
/* expected_attach_type is optional, if kernel doesn't support that */
SEC_EXP_ATTACH_OPT = 1,
/* legacy, only used by libbpf_get_type_names() and
* libbpf_attach_type_by_name(), not used by libbpf itself at all.
* This used to be associated with cgroup (and few other) BPF programs
* that were attachable through BPF_PROG_ATTACH command. Pretty
* meaningless nowadays, though.
*/
SEC_ATTACHABLE = 2,
SEC_ATTACHABLE_OPT = SEC_ATTACHABLE | SEC_EXP_ATTACH_OPT,
/* attachment target is specified through BTF ID in either kernel or
* other BPF program's BTF object
*/
SEC_ATTACH_BTF = 4,
/* BPF program type allows sleeping/blocking in kernel */
SEC_SLEEPABLE = 8,
/* BPF program support non-linear XDP buffer */
SEC_XDP_FRAGS = 16,
/* Setup proper attach type for usdt probes. */
SEC_USDT = 32,
};
struct bpf_sec_def {
char *sec;
enum bpf_prog_type prog_type;
enum bpf_attach_type expected_attach_type;
long cookie;
int handler_id;
libbpf_prog_setup_fn_t prog_setup_fn;
libbpf_prog_prepare_load_fn_t prog_prepare_load_fn;
libbpf_prog_attach_fn_t prog_attach_fn;
};
/*
* bpf_prog should be a better name but it has been used in
* linux/filter.h.
*/
struct bpf_program {
char *name;
char *sec_name;
size_t sec_idx;
const struct bpf_sec_def *sec_def;
/* this program's instruction offset (in number of instructions)
* within its containing ELF section
*/
size_t sec_insn_off;
/* number of original instructions in ELF section belonging to this
* program, not taking into account subprogram instructions possible
* appended later during relocation
*/
size_t sec_insn_cnt;
/* Offset (in number of instructions) of the start of instruction
* belonging to this BPF program within its containing main BPF
* program. For the entry-point (main) BPF program, this is always
* zero. For a sub-program, this gets reset before each of main BPF
* programs are processed and relocated and is used to determined
* whether sub-program was already appended to the main program, and
* if yes, at which instruction offset.
*/
size_t sub_insn_off;
/* instructions that belong to BPF program; insns[0] is located at
* sec_insn_off instruction within its ELF section in ELF file, so
* when mapping ELF file instruction index to the local instruction,
* one needs to subtract sec_insn_off; and vice versa.
*/
struct bpf_insn *insns;
/* actual number of instruction in this BPF program's image; for
* entry-point BPF programs this includes the size of main program
* itself plus all the used sub-programs, appended at the end
*/
size_t insns_cnt;
struct reloc_desc *reloc_desc;
int nr_reloc;
/* BPF verifier log settings */
char *log_buf;
size_t log_size;
__u32 log_level;
struct bpf_object *obj;
int fd;
bool autoload;
bool autoattach;
bool sym_global;
bool mark_btf_static;
enum bpf_prog_type type;
enum bpf_attach_type expected_attach_type;
int exception_cb_idx;
int prog_ifindex;
__u32 attach_btf_obj_fd;
__u32 attach_btf_id;
__u32 attach_prog_fd;
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_cnt;
void *line_info;
__u32 line_info_rec_size;
__u32 line_info_cnt;
__u32 prog_flags;
};
struct bpf_struct_ops {
struct bpf_program **progs;
__u32 *kern_func_off;
/* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
void *data;
/* e.g. struct bpf_struct_ops_tcp_congestion_ops in
* btf_vmlinux's format.
* struct bpf_struct_ops_tcp_congestion_ops {
* [... some other kernel fields ...]
* struct tcp_congestion_ops data;
* }
* kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
* bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
* from "data".
*/
void *kern_vdata;
__u32 type_id;
};
#define DATA_SEC ".data"
#define BSS_SEC ".bss"
#define RODATA_SEC ".rodata"
#define KCONFIG_SEC ".kconfig"
#define KSYMS_SEC ".ksyms"
#define STRUCT_OPS_SEC ".struct_ops"
#define STRUCT_OPS_LINK_SEC ".struct_ops.link"
#define ARENA_SEC ".addr_space.1"
enum libbpf_map_type {
LIBBPF_MAP_UNSPEC,
LIBBPF_MAP_DATA,
LIBBPF_MAP_BSS,
LIBBPF_MAP_RODATA,
LIBBPF_MAP_KCONFIG,
};
struct bpf_map_def {
unsigned int type;
unsigned int key_size;
unsigned int value_size;
unsigned int max_entries;
unsigned int map_flags;
};
struct bpf_map {
struct bpf_object *obj;
char *name;
/* real_name is defined for special internal maps (.rodata*,
* .data*, .bss, .kconfig) and preserves their original ELF section
* name. This is important to be able to find corresponding BTF
* DATASEC information.
*/
char *real_name;
int fd;
int sec_idx;
size_t sec_offset;
int map_ifindex;
int inner_map_fd;
struct bpf_map_def def;
__u32 numa_node;
__u32 btf_var_idx;
int mod_btf_fd;
__u32 btf_key_type_id;
__u32 btf_value_type_id;
__u32 btf_vmlinux_value_type_id;
enum libbpf_map_type libbpf_type;
void *mmaped;
struct bpf_struct_ops *st_ops;
struct bpf_map *inner_map;
void **init_slots;
int init_slots_sz;
char *pin_path;
bool pinned;
bool reused;
bool autocreate;
bool autoattach;
__u64 map_extra;
};
enum extern_type {
EXT_UNKNOWN,
EXT_KCFG,
EXT_KSYM,
};
enum kcfg_type {
KCFG_UNKNOWN,
KCFG_CHAR,
KCFG_BOOL,
KCFG_INT,
KCFG_TRISTATE,
KCFG_CHAR_ARR,
};
struct extern_desc {
enum extern_type type;
int sym_idx;
int btf_id;
int sec_btf_id;
const char *name;
char *essent_name;
bool is_set;
bool is_weak;
union {
struct {
enum kcfg_type type;
int sz;
int align;
int data_off;
bool is_signed;
} kcfg;
struct {
unsigned long long addr;
/* target btf_id of the corresponding kernel var. */
int kernel_btf_obj_fd;
int kernel_btf_id;
/* local btf_id of the ksym extern's type. */
__u32 type_id;
/* BTF fd index to be patched in for insn->off, this is
* 0 for vmlinux BTF, index in obj->fd_array for module
* BTF
*/
__s16 btf_fd_idx;
} ksym;
};
};
struct module_btf {
struct btf *btf;
char *name;
__u32 id;
int fd;
int fd_array_idx;
};
enum sec_type {
SEC_UNUSED = 0,
SEC_RELO,
SEC_BSS,
SEC_DATA,
SEC_RODATA,
SEC_ST_OPS,
};
struct elf_sec_desc {
enum sec_type sec_type;
Elf64_Shdr *shdr;
Elf_Data *data;
};
struct elf_state {
int fd;
const void *obj_buf;
size_t obj_buf_sz;
Elf *elf;
Elf64_Ehdr *ehdr;
Elf_Data *symbols;
Elf_Data *arena_data;
size_t shstrndx; /* section index for section name strings */
size_t strtabidx;
struct elf_sec_desc *secs;
size_t sec_cnt;
int btf_maps_shndx;
__u32 btf_maps_sec_btf_id;
int text_shndx;
int symbols_shndx;
bool has_st_ops;
int arena_data_shndx;
};
struct usdt_manager;
struct bpf_object {
char name[BPF_OBJ_NAME_LEN];
char license[64];
__u32 kern_version;
struct bpf_program *programs;
size_t nr_programs;
struct bpf_map *maps;
size_t nr_maps;
size_t maps_cap;
char *kconfig;
struct extern_desc *externs;
int nr_extern;
int kconfig_map_idx;
bool loaded;
bool has_subcalls;
bool has_rodata;
struct bpf_gen *gen_loader;
/* Information when doing ELF related work. Only valid if efile.elf is not NULL */
struct elf_state efile;
unsigned char byteorder;
struct btf *btf;
struct btf_ext *btf_ext;
/* Parse and load BTF vmlinux if any of the programs in the object need
* it at load time.
*/
struct btf *btf_vmlinux;
/* Path to the custom BTF to be used for BPF CO-RE relocations as an
* override for vmlinux BTF.
*/
char *btf_custom_path;
/* vmlinux BTF override for CO-RE relocations */
struct btf *btf_vmlinux_override;
/* Lazily initialized kernel module BTFs */
struct module_btf *btf_modules;
bool btf_modules_loaded;
size_t btf_module_cnt;
size_t btf_module_cap;
/* optional log settings passed to BPF_BTF_LOAD and BPF_PROG_LOAD commands */
char *log_buf;
size_t log_size;
__u32 log_level;
int *fd_array;
size_t fd_array_cap;
size_t fd_array_cnt;
struct usdt_manager *usdt_man;
struct bpf_map *arena_map;
void *arena_data;
size_t arena_data_sz;
struct kern_feature_cache *feat_cache;
char *token_path;
int token_fd;
char path[];
};
static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn);
static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx);
static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx);
void bpf_program__unload(struct bpf_program *prog)
{
if (!prog)
return;
zclose(prog->fd);
zfree(&prog->func_info);
zfree(&prog->line_info);
}
static void bpf_program__exit(struct bpf_program *prog)
{
if (!prog)
return;
bpf_program__unload(prog);
zfree(&prog->name);
zfree(&prog->sec_name);
zfree(&prog->insns);
zfree(&prog->reloc_desc);
prog->nr_reloc = 0;
prog->insns_cnt = 0;
prog->sec_idx = -1;
}
static bool insn_is_subprog_call(const struct bpf_insn *insn)
{
return BPF_CLASS(insn->code) == BPF_JMP &&
BPF_OP(insn->code) == BPF_CALL &&
BPF_SRC(insn->code) == BPF_K &&
insn->src_reg == BPF_PSEUDO_CALL &&
insn->dst_reg == 0 &&
insn->off == 0;
}
static bool is_call_insn(const struct bpf_insn *insn)
{
return insn->code == (BPF_JMP | BPF_CALL);
}
static bool insn_is_pseudo_func(struct bpf_insn *insn)
{
return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
}
static int
bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
const char *name, size_t sec_idx, const char *sec_name,
size_t sec_off, void *insn_data, size_t insn_data_sz)
{
if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
sec_name, name, sec_off, insn_data_sz);
return -EINVAL;
}
memset(prog, 0, sizeof(*prog));
prog->obj = obj;
prog->sec_idx = sec_idx;
prog->sec_insn_off = sec_off / BPF_INSN_SZ;
prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
/* insns_cnt can later be increased by appending used subprograms */
prog->insns_cnt = prog->sec_insn_cnt;
prog->type = BPF_PROG_TYPE_UNSPEC;
prog->fd = -1;
prog->exception_cb_idx = -1;
/* libbpf's convention for SEC("?abc...") is that it's just like
* SEC("abc...") but the corresponding bpf_program starts out with
* autoload set to false.
*/
if (sec_name[0] == '?') {
prog->autoload = false;
/* from now on forget there was ? in section name */
sec_name++;
} else {
prog->autoload = true;
}
prog->autoattach = true;
/* inherit object's log_level */
prog->log_level = obj->log_level;
prog->sec_name = strdup(sec_name);
if (!prog->sec_name)
goto errout;
prog->name = strdup(name);
if (!prog->name)
goto errout;
prog->insns = malloc(insn_data_sz);
if (!prog->insns)
goto errout;
memcpy(prog->insns, insn_data, insn_data_sz);
return 0;
errout:
pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
bpf_program__exit(prog);
return -ENOMEM;
}
static int
bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
const char *sec_name, int sec_idx)
{
Elf_Data *symbols = obj->efile.symbols;
struct bpf_program *prog, *progs;
void *data = sec_data->d_buf;
size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
int nr_progs, err, i;
const char *name;
Elf64_Sym *sym;
progs = obj->programs;
nr_progs = obj->nr_programs;
nr_syms = symbols->d_size / sizeof(Elf64_Sym);
for (i = 0; i < nr_syms; i++) {
sym = elf_sym_by_idx(obj, i);
if (sym->st_shndx != sec_idx)
continue;
if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
prog_sz = sym->st_size;
sec_off = sym->st_value;
name = elf_sym_str(obj, sym->st_name);
if (!name) {
pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
sec_name, sec_off);
return -LIBBPF_ERRNO__FORMAT;
}
if (sec_off + prog_sz > sec_sz) {
pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
sec_name, sec_off);
return -LIBBPF_ERRNO__FORMAT;
}
if (sec_idx != obj->efile.text_shndx && ELF64_ST_BIND(sym->st_info) == STB_LOCAL) {
pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
return -ENOTSUP;
}
pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
if (!progs) {
/*
* In this case the original obj->programs
* is still valid, so don't need special treat for
* bpf_close_object().
*/
pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
sec_name, name);
return -ENOMEM;
}
obj->programs = progs;
prog = &progs[nr_progs];
err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
sec_off, data + sec_off, prog_sz);
if (err)
return err;
if (ELF64_ST_BIND(sym->st_info) != STB_LOCAL)
prog->sym_global = true;
/* if function is a global/weak symbol, but has restricted
* (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF FUNC
* as static to enable more permissive BPF verification mode
* with more outside context available to BPF verifier
*/
if (prog->sym_global && (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL))
prog->mark_btf_static = true;
nr_progs++;
obj->nr_programs = nr_progs;
}
return 0;
}
static void bpf_object_bswap_progs(struct bpf_object *obj)
{
struct bpf_program *prog = obj->programs;
struct bpf_insn *insn;
int p, i;
for (p = 0; p < obj->nr_programs; p++, prog++) {
insn = prog->insns;
for (i = 0; i < prog->insns_cnt; i++, insn++)
bpf_insn_bswap(insn);
}
pr_debug("converted %zu BPF programs to native byte order\n", obj->nr_programs);
}
static const struct btf_member *
find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (btf_member_bit_offset(t, i) == bit_offset)
return m;
}
return NULL;
}
static const struct btf_member *
find_member_by_name(const struct btf *btf, const struct btf_type *t,
const char *name)
{
struct btf_member *m;
int i;
for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
return m;
}
return NULL;
}
static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
__u16 kind, struct btf **res_btf,
struct module_btf **res_mod_btf);
#define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
const char *name, __u32 kind);
static int
find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
struct module_btf **mod_btf,
const struct btf_type **type, __u32 *type_id,
const struct btf_type **vtype, __u32 *vtype_id,
const struct btf_member **data_member)
{
const struct btf_type *kern_type, *kern_vtype;
const struct btf_member *kern_data_member;
struct btf *btf = NULL;
__s32 kern_vtype_id, kern_type_id;
char tname[256];
__u32 i;
snprintf(tname, sizeof(tname), "%.*s",
(int)bpf_core_essential_name_len(tname_raw), tname_raw);
kern_type_id = find_ksym_btf_id(obj, tname, BTF_KIND_STRUCT,
&btf, mod_btf);
if (kern_type_id < 0) {
pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
tname);
return kern_type_id;
}
kern_type = btf__type_by_id(btf, kern_type_id);
/* Find the corresponding "map_value" type that will be used
* in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example,
* find "struct bpf_struct_ops_tcp_congestion_ops" from the
* btf_vmlinux.
*/
kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
tname, BTF_KIND_STRUCT);
if (kern_vtype_id < 0) {
pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
STRUCT_OPS_VALUE_PREFIX, tname);
return kern_vtype_id;
}
kern_vtype = btf__type_by_id(btf, kern_vtype_id);
/* Find "struct tcp_congestion_ops" from
* struct bpf_struct_ops_tcp_congestion_ops {
* [ ... ]
* struct tcp_congestion_ops data;
* }
*/
kern_data_member = btf_members(kern_vtype);
for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
if (kern_data_member->type == kern_type_id)
break;
}
if (i == btf_vlen(kern_vtype)) {
pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
tname, STRUCT_OPS_VALUE_PREFIX, tname);
return -EINVAL;
}
*type = kern_type;
*type_id = kern_type_id;
*vtype = kern_vtype;
*vtype_id = kern_vtype_id;
*data_member = kern_data_member;
return 0;
}
static bool bpf_map__is_struct_ops(const struct bpf_map *map)
{
return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
}
static bool is_valid_st_ops_program(struct bpf_object *obj,
const struct bpf_program *prog)
{
int i;
for (i = 0; i < obj->nr_programs; i++) {
if (&obj->programs[i] == prog)
return prog->type == BPF_PROG_TYPE_STRUCT_OPS;
}
return false;
}
/* For each struct_ops program P, referenced from some struct_ops map M,
* enable P.autoload if there are Ms for which M.autocreate is true,
* disable P.autoload if for all Ms M.autocreate is false.
* Don't change P.autoload for programs that are not referenced from any maps.
*/
static int bpf_object_adjust_struct_ops_autoload(struct bpf_object *obj)
{
struct bpf_program *prog, *slot_prog;
struct bpf_map *map;
int i, j, k, vlen;
for (i = 0; i < obj->nr_programs; ++i) {
int should_load = false;
int use_cnt = 0;
prog = &obj->programs[i];
if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
continue;
for (j = 0; j < obj->nr_maps; ++j) {
const struct btf_type *type;
map = &obj->maps[j];
if (!bpf_map__is_struct_ops(map))
continue;
type = btf__type_by_id(obj->btf, map->st_ops->type_id);
vlen = btf_vlen(type);
for (k = 0; k < vlen; ++k) {
slot_prog = map->st_ops->progs[k];
if (prog != slot_prog)
continue;
use_cnt++;
if (map->autocreate)
should_load = true;
}
}
if (use_cnt)
prog->autoload = should_load;
}
return 0;
}
/* Init the map's fields that depend on kern_btf */
static int bpf_map__init_kern_struct_ops(struct bpf_map *map)
{
const struct btf_member *member, *kern_member, *kern_data_member;
const struct btf_type *type, *kern_type, *kern_vtype;
__u32 i, kern_type_id, kern_vtype_id, kern_data_off;
struct bpf_object *obj = map->obj;
const struct btf *btf = obj->btf;
struct bpf_struct_ops *st_ops;
const struct btf *kern_btf;
struct module_btf *mod_btf = NULL;
void *data, *kern_data;
const char *tname;
int err;
st_ops = map->st_ops;
type = btf__type_by_id(btf, st_ops->type_id);
tname = btf__name_by_offset(btf, type->name_off);
err = find_struct_ops_kern_types(obj, tname, &mod_btf,
&kern_type, &kern_type_id,
&kern_vtype, &kern_vtype_id,
&kern_data_member);
if (err)
return err;
kern_btf = mod_btf ? mod_btf->btf : obj->btf_vmlinux;
pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
map->mod_btf_fd = mod_btf ? mod_btf->fd : -1;
map->def.value_size = kern_vtype->size;
map->btf_vmlinux_value_type_id = kern_vtype_id;
st_ops->kern_vdata = calloc(1, kern_vtype->size);
if (!st_ops->kern_vdata)
return -ENOMEM;
data = st_ops->data;
kern_data_off = kern_data_member->offset / 8;
kern_data = st_ops->kern_vdata + kern_data_off;
member = btf_members(type);
for (i = 0; i < btf_vlen(type); i++, member++) {
const struct btf_type *mtype, *kern_mtype;
__u32 mtype_id, kern_mtype_id;
void *mdata, *kern_mdata;
struct bpf_program *prog;
__s64 msize, kern_msize;
__u32 moff, kern_moff;
__u32 kern_member_idx;
const char *mname;
mname = btf__name_by_offset(btf, member->name_off);
moff = member->offset / 8;
mdata = data + moff;
msize = btf__resolve_size(btf, member->type);
if (msize < 0) {
pr_warn("struct_ops init_kern %s: failed to resolve the size of member %s\n",
map->name, mname);
return msize;
}
kern_member = find_member_by_name(kern_btf, kern_type, mname);
if (!kern_member) {
if (!libbpf_is_mem_zeroed(mdata, msize)) {
pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
map->name, mname);
return -ENOTSUP;
}
if (st_ops->progs[i]) {
/* If we had declaratively set struct_ops callback, we need to
* force its autoload to false, because it doesn't have
* a chance of succeeding from POV of the current struct_ops map.
* If this program is still referenced somewhere else, though,
* then bpf_object_adjust_struct_ops_autoload() will update its
* autoload accordingly.
*/
st_ops->progs[i]->autoload = false;
st_ops->progs[i] = NULL;
}
/* Skip all-zero/NULL fields if they are not present in the kernel BTF */
pr_info("struct_ops %s: member %s not found in kernel, skipping it as it's set to zero\n",
map->name, mname);
continue;
}
kern_member_idx = kern_member - btf_members(kern_type);
if (btf_member_bitfield_size(type, i) ||
btf_member_bitfield_size(kern_type, kern_member_idx)) {
pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
map->name, mname);
return -ENOTSUP;
}
kern_moff = kern_member->offset / 8;
kern_mdata = kern_data + kern_moff;
mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
&kern_mtype_id);
if (BTF_INFO_KIND(mtype->info) !=
BTF_INFO_KIND(kern_mtype->info)) {
pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
map->name, mname, BTF_INFO_KIND(mtype->info),
BTF_INFO_KIND(kern_mtype->info));
return -ENOTSUP;
}
if (btf_is_ptr(mtype)) {
prog = *(void **)mdata;
/* just like for !kern_member case above, reset declaratively
* set (at compile time) program's autload to false,
* if user replaced it with another program or NULL
*/
if (st_ops->progs[i] && st_ops->progs[i] != prog)
st_ops->progs[i]->autoload = false;
/* Update the value from the shadow type */
st_ops->progs[i] = prog;
if (!prog)
continue;
if (!is_valid_st_ops_program(obj, prog)) {
pr_warn("struct_ops init_kern %s: member %s is not a struct_ops program\n",
map->name, mname);
return -ENOTSUP;
}
kern_mtype = skip_mods_and_typedefs(kern_btf,
kern_mtype->type,
&kern_mtype_id);
/* mtype->type must be a func_proto which was
* guaranteed in bpf_object__collect_st_ops_relos(),
* so only check kern_mtype for func_proto here.
*/
if (!btf_is_func_proto(kern_mtype)) {
pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
map->name, mname);
return -ENOTSUP;
}
if (mod_btf)
prog->attach_btf_obj_fd = mod_btf->fd;
/* if we haven't yet processed this BPF program, record proper
* attach_btf_id and member_idx
*/
if (!prog->attach_btf_id) {
prog->attach_btf_id = kern_type_id;
prog->expected_attach_type = kern_member_idx;
}
/* struct_ops BPF prog can be re-used between multiple
* .struct_ops & .struct_ops.link as long as it's the
* same struct_ops struct definition and the same
* function pointer field
*/
if (prog->attach_btf_id != kern_type_id) {
pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: attach_btf_id %u != kern_type_id %u\n",
map->name, mname, prog->name, prog->sec_name, prog->type,
prog->attach_btf_id, kern_type_id);
return -EINVAL;
}
if (prog->expected_attach_type != kern_member_idx) {
pr_warn("struct_ops init_kern %s func ptr %s: invalid reuse of prog %s in sec %s with type %u: expected_attach_type %u != kern_member_idx %u\n",
map->name, mname, prog->name, prog->sec_name, prog->type,
prog->expected_attach_type, kern_member_idx);
return -EINVAL;
}
st_ops->kern_func_off[i] = kern_data_off + kern_moff;
pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
map->name, mname, prog->name, moff,
kern_moff);
continue;
}
kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
if (kern_msize < 0 || msize != kern_msize) {
pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
map->name, mname, (ssize_t)msize,
(ssize_t)kern_msize);
return -ENOTSUP;
}
pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
map->name, mname, (unsigned int)msize,
moff, kern_moff);
memcpy(kern_mdata, mdata, msize);
}
return 0;
}
static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
{
struct bpf_map *map;
size_t i;
int err;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!bpf_map__is_struct_ops(map))
continue;
if (!map->autocreate)
continue;
err = bpf_map__init_kern_struct_ops(map);
if (err)
return err;
}
return 0;
}
static int init_struct_ops_maps(struct bpf_object *obj, const char *sec_name,
int shndx, Elf_Data *data)
{
const struct btf_type *type, *datasec;
const struct btf_var_secinfo *vsi;
struct bpf_struct_ops *st_ops;
const char *tname, *var_name;
__s32 type_id, datasec_id;
const struct btf *btf;
struct bpf_map *map;
__u32 i;
if (shndx == -1)
return 0;
btf = obj->btf;
datasec_id = btf__find_by_name_kind(btf, sec_name,
BTF_KIND_DATASEC);
if (datasec_id < 0) {
pr_warn("struct_ops init: DATASEC %s not found\n",
sec_name);
return -EINVAL;
}
datasec = btf__type_by_id(btf, datasec_id);
vsi = btf_var_secinfos(datasec);
for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
type = btf__type_by_id(obj->btf, vsi->type);
var_name = btf__name_by_offset(obj->btf, type->name_off);
type_id = btf__resolve_type(obj->btf, vsi->type);
if (type_id < 0) {
pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
vsi->type, sec_name);
return -EINVAL;
}
type = btf__type_by_id(obj->btf, type_id);
tname = btf__name_by_offset(obj->btf, type->name_off);
if (!tname[0]) {
pr_warn("struct_ops init: anonymous type is not supported\n");
return -ENOTSUP;
}
if (!btf_is_struct(type)) {
pr_warn("struct_ops init: %s is not a struct\n", tname);
return -EINVAL;
}
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->sec_idx = shndx;
map->sec_offset = vsi->offset;
map->name = strdup(var_name);
if (!map->name)
return -ENOMEM;
map->btf_value_type_id = type_id;
/* Follow same convention as for programs autoload:
* SEC("?.struct_ops") means map is not created by default.
*/
if (sec_name[0] == '?') {
map->autocreate = false;
/* from now on forget there was ? in section name */
sec_name++;
}
map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
map->def.key_size = sizeof(int);
map->def.value_size = type->size;
map->def.max_entries = 1;
map->def.map_flags = strcmp(sec_name, STRUCT_OPS_LINK_SEC) == 0 ? BPF_F_LINK : 0;
map->autoattach = true;
map->st_ops = calloc(1, sizeof(*map->st_ops));
if (!map->st_ops)
return -ENOMEM;
st_ops = map->st_ops;
st_ops->data = malloc(type->size);
st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
st_ops->kern_func_off = malloc(btf_vlen(type) *
sizeof(*st_ops->kern_func_off));
if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
return -ENOMEM;
if (vsi->offset + type->size > data->d_size) {
pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
var_name, sec_name);
return -EINVAL;
}
memcpy(st_ops->data,
data->d_buf + vsi->offset,
type->size);
st_ops->type_id = type_id;
pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
tname, type_id, var_name, vsi->offset);
}
return 0;
}
static int bpf_object_init_struct_ops(struct bpf_object *obj)
{
const char *sec_name;
int sec_idx, err;
for (sec_idx = 0; sec_idx < obj->efile.sec_cnt; ++sec_idx) {
struct elf_sec_desc *desc = &obj->efile.secs[sec_idx];
if (desc->sec_type != SEC_ST_OPS)
continue;
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
if (!sec_name)
return -LIBBPF_ERRNO__FORMAT;
err = init_struct_ops_maps(obj, sec_name, sec_idx, desc->data);
if (err)
return err;
}
return 0;
}
static struct bpf_object *bpf_object__new(const char *path,
const void *obj_buf,
size_t obj_buf_sz,
const char *obj_name)
{
struct bpf_object *obj;
char *end;
obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
if (!obj) {
pr_warn("alloc memory failed for %s\n", path);
return ERR_PTR(-ENOMEM);
}
strcpy(obj->path, path);
if (obj_name) {
libbpf_strlcpy(obj->name, obj_name, sizeof(obj->name));
} else {
/* Using basename() GNU version which doesn't modify arg. */
libbpf_strlcpy(obj->name, basename((void *)path), sizeof(obj->name));
end = strchr(obj->name, '.');
if (end)
*end = 0;
}
obj->efile.fd = -1;
/*
* Caller of this function should also call
* bpf_object__elf_finish() after data collection to return
* obj_buf to user. If not, we should duplicate the buffer to
* avoid user freeing them before elf finish.
*/
obj->efile.obj_buf = obj_buf;
obj->efile.obj_buf_sz = obj_buf_sz;
obj->efile.btf_maps_shndx = -1;
obj->kconfig_map_idx = -1;
obj->kern_version = get_kernel_version();
obj->loaded = false;
return obj;
}
static void bpf_object__elf_finish(struct bpf_object *obj)
{
if (!obj->efile.elf)
return;
elf_end(obj->efile.elf);
obj->efile.elf = NULL;
obj->efile.ehdr = NULL;
obj->efile.symbols = NULL;
obj->efile.arena_data = NULL;
zfree(&obj->efile.secs);
obj->efile.sec_cnt = 0;
zclose(obj->efile.fd);
obj->efile.obj_buf = NULL;
obj->efile.obj_buf_sz = 0;
}
static int bpf_object__elf_init(struct bpf_object *obj)
{
Elf64_Ehdr *ehdr;
int err = 0;
Elf *elf;
if (obj->efile.elf) {
pr_warn("elf: init internal error\n");
return -LIBBPF_ERRNO__LIBELF;
}
if (obj->efile.obj_buf_sz > 0) {
/* obj_buf should have been validated by bpf_object__open_mem(). */
elf = elf_memory((char *)obj->efile.obj_buf, obj->efile.obj_buf_sz);
} else {
obj->efile.fd = open(obj->path, O_RDONLY | O_CLOEXEC);
if (obj->efile.fd < 0) {
err = -errno;
pr_warn("elf: failed to open %s: %s\n", obj->path, errstr(err));
return err;
}
elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
}
if (!elf) {
pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__LIBELF;
goto errout;
}
obj->efile.elf = elf;
if (elf_kind(elf) != ELF_K_ELF) {
err = -LIBBPF_ERRNO__FORMAT;
pr_warn("elf: '%s' is not a proper ELF object\n", obj->path);
goto errout;
}
if (gelf_getclass(elf) != ELFCLASS64) {
err = -LIBBPF_ERRNO__FORMAT;
pr_warn("elf: '%s' is not a 64-bit ELF object\n", obj->path);
goto errout;
}
obj->efile.ehdr = ehdr = elf64_getehdr(elf);
if (!obj->efile.ehdr) {
pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
/* Validate ELF object endianness... */
if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
err = -LIBBPF_ERRNO__ENDIAN;
pr_warn("elf: '%s' has unknown byte order\n", obj->path);
goto errout;
}
/* and save after bpf_object_open() frees ELF data */
obj->byteorder = ehdr->e_ident[EI_DATA];
if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) {
pr_warn("elf: failed to get section names section index for %s: %s\n",
obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
/* ELF is corrupted/truncated, avoid calling elf_strptr. */
if (!elf_rawdata(elf_getscn(elf, obj->efile.shstrndx), NULL)) {
pr_warn("elf: failed to get section names strings from %s: %s\n",
obj->path, elf_errmsg(-1));
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
/* Old LLVM set e_machine to EM_NONE */
if (ehdr->e_type != ET_REL || (ehdr->e_machine && ehdr->e_machine != EM_BPF)) {
pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
err = -LIBBPF_ERRNO__FORMAT;
goto errout;
}
return 0;
errout:
bpf_object__elf_finish(obj);
return err;
}
static bool is_native_endianness(struct bpf_object *obj)
{
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
return obj->byteorder == ELFDATA2LSB;
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
return obj->byteorder == ELFDATA2MSB;
#else
# error "Unrecognized __BYTE_ORDER__"
#endif
}
static int
bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
{
if (!data) {
pr_warn("invalid license section in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
/* libbpf_strlcpy() only copies first N - 1 bytes, so size + 1 won't
* go over allowed ELF data section buffer
*/
libbpf_strlcpy(obj->license, data, min(size + 1, sizeof(obj->license)));
pr_debug("license of %s is %s\n", obj->path, obj->license);
return 0;
}
static int
bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
{
__u32 kver;
if (!data || size != sizeof(kver)) {
pr_warn("invalid kver section in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
memcpy(&kver, data, sizeof(kver));
obj->kern_version = kver;
pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
return 0;
}
static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
{
if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
type == BPF_MAP_TYPE_HASH_OF_MAPS)
return true;
return false;
}
static int find_elf_sec_sz(const struct bpf_object *obj, const char *name, __u32 *size)
{
Elf_Data *data;
Elf_Scn *scn;
if (!name)
return -EINVAL;
scn = elf_sec_by_name(obj, name);
data = elf_sec_data(obj, scn);
if (data) {
*size = data->d_size;
return 0; /* found it */
}
return -ENOENT;
}
static Elf64_Sym *find_elf_var_sym(const struct bpf_object *obj, const char *name)
{
Elf_Data *symbols = obj->efile.symbols;
const char *sname;
size_t si;
for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
Elf64_Sym *sym = elf_sym_by_idx(obj, si);
if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
continue;
if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
ELF64_ST_BIND(sym->st_info) != STB_WEAK)
continue;
sname = elf_sym_str(obj, sym->st_name);
if (!sname) {
pr_warn("failed to get sym name string for var %s\n", name);
return ERR_PTR(-EIO);
}
if (strcmp(name, sname) == 0)
return sym;
}
return ERR_PTR(-ENOENT);
}
/* Some versions of Android don't provide memfd_create() in their libc
* implementation, so avoid complications and just go straight to Linux
* syscall.
*/
static int sys_memfd_create(const char *name, unsigned flags)
{
return syscall(__NR_memfd_create, name, flags);
}
#ifndef MFD_CLOEXEC
#define MFD_CLOEXEC 0x0001U
#endif
static int create_placeholder_fd(void)
{
int fd;
fd = ensure_good_fd(sys_memfd_create("libbpf-placeholder-fd", MFD_CLOEXEC));
if (fd < 0)
return -errno;
return fd;
}
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
{
struct bpf_map *map;
int err;
err = libbpf_ensure_mem((void **)&obj->maps, &obj->maps_cap,
sizeof(*obj->maps), obj->nr_maps + 1);
if (err)
return ERR_PTR(err);
map = &obj->maps[obj->nr_maps++];
map->obj = obj;
/* Preallocate map FD without actually creating BPF map just yet.
* These map FD "placeholders" will be reused later without changing
* FD value when map is actually created in the kernel.
*
* This is useful to be able to perform BPF program relocations
* without having to create BPF maps before that step. This allows us
* to finalize and load BTF very late in BPF object's loading phase,
* right before BPF maps have to be created and BPF programs have to
* be loaded. By having these map FD placeholders we can perform all
* the sanitizations, relocations, and any other adjustments before we
* start creating actual BPF kernel objects (BTF, maps, progs).
*/
map->fd = create_placeholder_fd();
if (map->fd < 0)
return ERR_PTR(map->fd);
map->inner_map_fd = -1;
map->autocreate = true;
return map;
}
static size_t array_map_mmap_sz(unsigned int value_sz, unsigned int max_entries)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
size_t map_sz;
map_sz = (size_t)roundup(value_sz, 8) * max_entries;
map_sz = roundup(map_sz, page_sz);
return map_sz;
}
static size_t bpf_map_mmap_sz(const struct bpf_map *map)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
switch (map->def.type) {
case BPF_MAP_TYPE_ARRAY:
return array_map_mmap_sz(map->def.value_size, map->def.max_entries);
case BPF_MAP_TYPE_ARENA:
return page_sz * map->def.max_entries;
default:
return 0; /* not supported */
}
}
static int bpf_map_mmap_resize(struct bpf_map *map, size_t old_sz, size_t new_sz)
{
void *mmaped;
if (!map->mmaped)
return -EINVAL;
if (old_sz == new_sz)
return 0;
mmaped = mmap(NULL, new_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (mmaped == MAP_FAILED)
return -errno;
memcpy(mmaped, map->mmaped, min(old_sz, new_sz));
munmap(map->mmaped, old_sz);
map->mmaped = mmaped;
return 0;
}
static char *internal_map_name(struct bpf_object *obj, const char *real_name)
{
char map_name[BPF_OBJ_NAME_LEN], *p;
int pfx_len, sfx_len = max((size_t)7, strlen(real_name));
/* This is one of the more confusing parts of libbpf for various
* reasons, some of which are historical. The original idea for naming
* internal names was to include as much of BPF object name prefix as
* possible, so that it can be distinguished from similar internal
* maps of a different BPF object.
* As an example, let's say we have bpf_object named 'my_object_name'
* and internal map corresponding to '.rodata' ELF section. The final
* map name advertised to user and to the kernel will be
* 'my_objec.rodata', taking first 8 characters of object name and
* entire 7 characters of '.rodata'.
* Somewhat confusingly, if internal map ELF section name is shorter
* than 7 characters, e.g., '.bss', we still reserve 7 characters
* for the suffix, even though we only have 4 actual characters, and
* resulting map will be called 'my_objec.bss', not even using all 15
* characters allowed by the kernel. Oh well, at least the truncated
* object name is somewhat consistent in this case. But if the map
* name is '.kconfig', we'll still have entirety of '.kconfig' added
* (8 chars) and thus will be left with only first 7 characters of the
* object name ('my_obje'). Happy guessing, user, that the final map
* name will be "my_obje.kconfig".
* Now, with libbpf starting to support arbitrarily named .rodata.*
* and .data.* data sections, it's possible that ELF section name is
* longer than allowed 15 chars, so we now need to be careful to take
* only up to 15 first characters of ELF name, taking no BPF object
* name characters at all. So '.rodata.abracadabra' will result in
* '.rodata.abracad' kernel and user-visible name.
* We need to keep this convoluted logic intact for .data, .bss and
* .rodata maps, but for new custom .data.custom and .rodata.custom
* maps we use their ELF names as is, not prepending bpf_object name
* in front. We still need to truncate them to 15 characters for the
* kernel. Full name can be recovered for such maps by using DATASEC
* BTF type associated with such map's value type, though.
*/
if (sfx_len >= BPF_OBJ_NAME_LEN)
sfx_len = BPF_OBJ_NAME_LEN - 1;
/* if there are two or more dots in map name, it's a custom dot map */
if (strchr(real_name + 1, '.') != NULL)
pfx_len = 0;
else
pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1, strlen(obj->name));
snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
sfx_len, real_name);
/* sanities map name to characters allowed by kernel */
for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
if (!isalnum(*p) && *p != '_' && *p != '.')
*p = '_';
return strdup(map_name);
}
static int
map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map);
/* Internal BPF map is mmap()'able only if at least one of corresponding
* DATASEC's VARs are to be exposed through BPF skeleton. I.e., it's a GLOBAL
* variable and it's not marked as __hidden (which turns it into, effectively,
* a STATIC variable).
*/
static bool map_is_mmapable(struct bpf_object *obj, struct bpf_map *map)
{
const struct btf_type *t, *vt;
struct btf_var_secinfo *vsi;
int i, n;
if (!map->btf_value_type_id)
return false;
t = btf__type_by_id(obj->btf, map->btf_value_type_id);
if (!btf_is_datasec(t))
return false;
vsi = btf_var_secinfos(t);
for (i = 0, n = btf_vlen(t); i < n; i++, vsi++) {
vt = btf__type_by_id(obj->btf, vsi->type);
if (!btf_is_var(vt))
continue;
if (btf_var(vt)->linkage != BTF_VAR_STATIC)
return true;
}
return false;
}
static int
bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
const char *real_name, int sec_idx, void *data, size_t data_sz)
{
struct bpf_map_def *def;
struct bpf_map *map;
size_t mmap_sz;
int err;
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->libbpf_type = type;
map->sec_idx = sec_idx;
map->sec_offset = 0;
map->real_name = strdup(real_name);
map->name = internal_map_name(obj, real_name);
if (!map->real_name || !map->name) {
zfree(&map->real_name);
zfree(&map->name);
return -ENOMEM;
}
def = &map->def;
def->type = BPF_MAP_TYPE_ARRAY;
def->key_size = sizeof(int);
def->value_size = data_sz;
def->max_entries = 1;
def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
? BPF_F_RDONLY_PROG : 0;
/* failures are fine because of maps like .rodata.str1.1 */
(void) map_fill_btf_type_info(obj, map);
if (map_is_mmapable(obj, map))
def->map_flags |= BPF_F_MMAPABLE;
pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
map->name, map->sec_idx, map->sec_offset, def->map_flags);
mmap_sz = bpf_map_mmap_sz(map);
map->mmaped = mmap(NULL, mmap_sz, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (map->mmaped == MAP_FAILED) {
err = -errno;
map->mmaped = NULL;
pr_warn("failed to alloc map '%s' content buffer: %s\n", map->name, errstr(err));
zfree(&map->real_name);
zfree(&map->name);
return err;
}
if (data)
memcpy(map->mmaped, data, data_sz);
pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
return 0;
}
static int bpf_object__init_global_data_maps(struct bpf_object *obj)
{
struct elf_sec_desc *sec_desc;
const char *sec_name;
int err = 0, sec_idx;
/*
* Populate obj->maps with libbpf internal maps.
*/
for (sec_idx = 1; sec_idx < obj->efile.sec_cnt; sec_idx++) {
sec_desc = &obj->efile.secs[sec_idx];
/* Skip recognized sections with size 0. */
if (!sec_desc->data || sec_desc->data->d_size == 0)
continue;
switch (sec_desc->sec_type) {
case SEC_DATA:
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
sec_name, sec_idx,
sec_desc->data->d_buf,
sec_desc->data->d_size);
break;
case SEC_RODATA:
obj->has_rodata = true;
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
sec_name, sec_idx,
sec_desc->data->d_buf,
sec_desc->data->d_size);
break;
case SEC_BSS:
sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, sec_idx));
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
sec_name, sec_idx,
NULL,
sec_desc->data->d_size);
break;
default:
/* skip */
break;
}
if (err)
return err;
}
return 0;
}
static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
const void *name)
{
int i;
for (i = 0; i < obj->nr_extern; i++) {
if (strcmp(obj->externs[i].name, name) == 0)
return &obj->externs[i];
}
return NULL;
}
static struct extern_desc *find_extern_by_name_with_len(const struct bpf_object *obj,
const void *name, int len)
{
const char *ext_name;
int i;
for (i = 0; i < obj->nr_extern; i++) {
ext_name = obj->externs[i].name;
if (strlen(ext_name) == len && strncmp(ext_name, name, len) == 0)
return &obj->externs[i];
}
return NULL;
}
static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
char value)
{
switch (ext->kcfg.type) {
case KCFG_BOOL:
if (value == 'm') {
pr_warn("extern (kcfg) '%s': value '%c' implies tristate or char type\n",
ext->name, value);
return -EINVAL;
}
*(bool *)ext_val = value == 'y' ? true : false;
break;
case KCFG_TRISTATE:
if (value == 'y')
*(enum libbpf_tristate *)ext_val = TRI_YES;
else if (value == 'm')
*(enum libbpf_tristate *)ext_val = TRI_MODULE;
else /* value == 'n' */
*(enum libbpf_tristate *)ext_val = TRI_NO;
break;
case KCFG_CHAR:
*(char *)ext_val = value;
break;
case KCFG_UNKNOWN:
case KCFG_INT:
case KCFG_CHAR_ARR:
default:
pr_warn("extern (kcfg) '%s': value '%c' implies bool, tristate, or char type\n",
ext->name, value);
return -EINVAL;
}
ext->is_set = true;
return 0;
}
static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
const char *value)
{
size_t len;
if (ext->kcfg.type != KCFG_CHAR_ARR) {
pr_warn("extern (kcfg) '%s': value '%s' implies char array type\n",
ext->name, value);
return -EINVAL;
}
len = strlen(value);
if (value[len - 1] != '"') {
pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
ext->name, value);
return -EINVAL;
}
/* strip quotes */
len -= 2;
if (len >= ext->kcfg.sz) {
pr_warn("extern (kcfg) '%s': long string '%s' of (%zu bytes) truncated to %d bytes\n",
ext->name, value, len, ext->kcfg.sz - 1);
len = ext->kcfg.sz - 1;
}
memcpy(ext_val, value + 1, len);
ext_val[len] = '\0';
ext->is_set = true;
return 0;
}
static int parse_u64(const char *value, __u64 *res)
{
char *value_end;
int err;
errno = 0;
*res = strtoull(value, &value_end, 0);
if (errno) {
err = -errno;
pr_warn("failed to parse '%s': %s\n", value, errstr(err));
return err;
}
if (*value_end) {
pr_warn("failed to parse '%s' as integer completely\n", value);
return -EINVAL;
}
return 0;
}
static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
{
int bit_sz = ext->kcfg.sz * 8;
if (ext->kcfg.sz == 8)
return true;
/* Validate that value stored in u64 fits in integer of `ext->sz`
* bytes size without any loss of information. If the target integer
* is signed, we rely on the following limits of integer type of
* Y bits and subsequent transformation:
*
* -2^(Y-1) <= X <= 2^(Y-1) - 1
* 0 <= X + 2^(Y-1) <= 2^Y - 1
* 0 <= X + 2^(Y-1) < 2^Y
*
* For unsigned target integer, check that all the (64 - Y) bits are
* zero.
*/
if (ext->kcfg.is_signed)
return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
else
return (v >> bit_sz) == 0;
}
static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
__u64 value)
{
if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR &&
ext->kcfg.type != KCFG_BOOL) {
pr_warn("extern (kcfg) '%s': value '%llu' implies integer, char, or boolean type\n",
ext->name, (unsigned long long)value);
return -EINVAL;
}
if (ext->kcfg.type == KCFG_BOOL && value > 1) {
pr_warn("extern (kcfg) '%s': value '%llu' isn't boolean compatible\n",
ext->name, (unsigned long long)value);
return -EINVAL;
}
if (!is_kcfg_value_in_range(ext, value)) {
pr_warn("extern (kcfg) '%s': value '%llu' doesn't fit in %d bytes\n",
ext->name, (unsigned long long)value, ext->kcfg.sz);
return -ERANGE;
}
switch (ext->kcfg.sz) {
case 1:
*(__u8 *)ext_val = value;
break;
case 2:
*(__u16 *)ext_val = value;
break;
case 4:
*(__u32 *)ext_val = value;
break;
case 8:
*(__u64 *)ext_val = value;
break;
default:
return -EINVAL;
}
ext->is_set = true;
return 0;
}
static int bpf_object__process_kconfig_line(struct bpf_object *obj,
char *buf, void *data)
{
struct extern_desc *ext;
char *sep, *value;
int len, err = 0;
void *ext_val;
__u64 num;
if (!str_has_pfx(buf, "CONFIG_"))
return 0;
sep = strchr(buf, '=');
if (!sep) {
pr_warn("failed to parse '%s': no separator\n", buf);
return -EINVAL;
}
/* Trim ending '\n' */
len = strlen(buf);
if (buf[len - 1] == '\n')
buf[len - 1] = '\0';
/* Split on '=' and ensure that a value is present. */
*sep = '\0';
if (!sep[1]) {
*sep = '=';
pr_warn("failed to parse '%s': no value\n", buf);
return -EINVAL;
}
ext = find_extern_by_name(obj, buf);
if (!ext || ext->is_set)
return 0;
ext_val = data + ext->kcfg.data_off;
value = sep + 1;
switch (*value) {
case 'y': case 'n': case 'm':
err = set_kcfg_value_tri(ext, ext_val, *value);
break;
case '"':
err = set_kcfg_value_str(ext, ext_val, value);
break;
default:
/* assume integer */
err = parse_u64(value, &num);
if (err) {
pr_warn("extern (kcfg) '%s': value '%s' isn't a valid integer\n", ext->name, value);
return err;
}
if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
pr_warn("extern (kcfg) '%s': value '%s' implies integer type\n", ext->name, value);
return -EINVAL;
}
err = set_kcfg_value_num(ext, ext_val, num);
break;
}
if (err)
return err;
pr_debug("extern (kcfg) '%s': set to %s\n", ext->name, value);
return 0;
}
static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
{
char buf[PATH_MAX];
struct utsname uts;
int len, err = 0;
gzFile file;
uname(&uts);
len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
if (len < 0)
return -EINVAL;
else if (len >= PATH_MAX)
return -ENAMETOOLONG;
/* gzopen also accepts uncompressed files. */
file = gzopen(buf, "re");
if (!file)
file = gzopen("/proc/config.gz", "re");
if (!file) {
pr_warn("failed to open system Kconfig\n");
return -ENOENT;
}
while (gzgets(file, buf, sizeof(buf))) {
err = bpf_object__process_kconfig_line(obj, buf, data);
if (err) {
pr_warn("error parsing system Kconfig line '%s': %s\n",
buf, errstr(err));
goto out;
}
}
out:
gzclose(file);
return err;
}
static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
const char *config, void *data)
{
char buf[PATH_MAX];
int err = 0;
FILE *file;
file = fmemopen((void *)config, strlen(config), "r");
if (!file) {
err = -errno;
pr_warn("failed to open in-memory Kconfig: %s\n", errstr(err));
return err;
}
while (fgets(buf, sizeof(buf), file)) {
err = bpf_object__process_kconfig_line(obj, buf, data);
if (err) {
pr_warn("error parsing in-memory Kconfig line '%s': %s\n",
buf, errstr(err));
break;
}
}
fclose(file);
return err;
}
static int bpf_object__init_kconfig_map(struct bpf_object *obj)
{
struct extern_desc *last_ext = NULL, *ext;
size_t map_sz;
int i, err;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type == EXT_KCFG)
last_ext = ext;
}
if (!last_ext)
return 0;
map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
".kconfig", obj->efile.symbols_shndx,
NULL, map_sz);
if (err)
return err;
obj->kconfig_map_idx = obj->nr_maps - 1;
return 0;
}
const struct btf_type *
skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
{
const struct btf_type *t = btf__type_by_id(btf, id);
if (res_id)
*res_id = id;
while (btf_is_mod(t) || btf_is_typedef(t)) {
if (res_id)
*res_id = t->type;
t = btf__type_by_id(btf, t->type);
}
return t;
}
static const struct btf_type *
resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
{
const struct btf_type *t;
t = skip_mods_and_typedefs(btf, id, NULL);
if (!btf_is_ptr(t))
return NULL;
t = skip_mods_and_typedefs(btf, t->type, res_id);
return btf_is_func_proto(t) ? t : NULL;
}
static const char *__btf_kind_str(__u16 kind)
{
switch (kind) {
case BTF_KIND_UNKN: return "void";
case BTF_KIND_INT: return "int";
case BTF_KIND_PTR: return "ptr";
case BTF_KIND_ARRAY: return "array";
case BTF_KIND_STRUCT: return "struct";
case BTF_KIND_UNION: return "union";
case BTF_KIND_ENUM: return "enum";
case BTF_KIND_FWD: return "fwd";
case BTF_KIND_TYPEDEF: return "typedef";
case BTF_KIND_VOLATILE: return "volatile";
case BTF_KIND_CONST: return "const";
case BTF_KIND_RESTRICT: return "restrict";
case BTF_KIND_FUNC: return "func";
case BTF_KIND_FUNC_PROTO: return "func_proto";
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
case BTF_KIND_FLOAT: return "float";
case BTF_KIND_DECL_TAG: return "decl_tag";
case BTF_KIND_TYPE_TAG: return "type_tag";
case BTF_KIND_ENUM64: return "enum64";
default: return "unknown";
}
}
const char *btf_kind_str(const struct btf_type *t)
{
return __btf_kind_str(btf_kind(t));
}
/*
* Fetch integer attribute of BTF map definition. Such attributes are
* represented using a pointer to an array, in which dimensionality of array
* encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
* encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
* type definition, while using only sizeof(void *) space in ELF data section.
*/
static bool get_map_field_int(const char *map_name, const struct btf *btf,
const struct btf_member *m, __u32 *res)
{
const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
const char *name = btf__name_by_offset(btf, m->name_off);
const struct btf_array *arr_info;
const struct btf_type *arr_t;
if (!btf_is_ptr(t)) {
pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
map_name, name, btf_kind_str(t));
return false;
}
arr_t = btf__type_by_id(btf, t->type);
if (!arr_t) {
pr_warn("map '%s': attr '%s': type [%u] not found.\n",
map_name, name, t->type);
return false;
}
if (!btf_is_array(arr_t)) {
pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
map_name, name, btf_kind_str(arr_t));
return false;
}
arr_info = btf_array(arr_t);
*res = arr_info->nelems;
return true;
}
static bool get_map_field_long(const char *map_name, const struct btf *btf,
const struct btf_member *m, __u64 *res)
{
const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
const char *name = btf__name_by_offset(btf, m->name_off);
if (btf_is_ptr(t)) {
__u32 res32;
bool ret;
ret = get_map_field_int(map_name, btf, m, &res32);
if (ret)
*res = (__u64)res32;
return ret;
}
if (!btf_is_enum(t) && !btf_is_enum64(t)) {
pr_warn("map '%s': attr '%s': expected ENUM or ENUM64, got %s.\n",
map_name, name, btf_kind_str(t));
return false;
}
if (btf_vlen(t) != 1) {
pr_warn("map '%s': attr '%s': invalid __ulong\n",
map_name, name);
return false;
}
if (btf_is_enum(t)) {
const struct btf_enum *e = btf_enum(t);
*res = e->val;
} else {
const struct btf_enum64 *e = btf_enum64(t);
*res = btf_enum64_value(e);
}
return true;
}
static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
{
int len;
len = snprintf(buf, buf_sz, "%s/%s", path, name);
if (len < 0)
return -EINVAL;
if (len >= buf_sz)
return -ENAMETOOLONG;
return 0;
}
static int build_map_pin_path(struct bpf_map *map, const char *path)
{
char buf[PATH_MAX];
int err;
if (!path)
path = BPF_FS_DEFAULT_PATH;
err = pathname_concat(buf, sizeof(buf), path, bpf_map__name(map));
if (err)
return err;
return bpf_map__set_pin_path(map, buf);
}
/* should match definition in bpf_helpers.h */
enum libbpf_pin_type {
LIBBPF_PIN_NONE,
/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
LIBBPF_PIN_BY_NAME,
};
int parse_btf_map_def(const char *map_name, struct btf *btf,
const struct btf_type *def_t, bool strict,
struct btf_map_def *map_def, struct btf_map_def *inner_def)
{
const struct btf_type *t;
const struct btf_member *m;
bool is_inner = inner_def == NULL;
int vlen, i;
vlen = btf_vlen(def_t);
m = btf_members(def_t);
for (i = 0; i < vlen; i++, m++) {
const char *name = btf__name_by_offset(btf, m->name_off);
if (!name) {
pr_warn("map '%s': invalid field #%d.\n", map_name, i);
return -EINVAL;
}
if (strcmp(name, "type") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
return -EINVAL;
map_def->parts |= MAP_DEF_MAP_TYPE;
} else if (strcmp(name, "max_entries") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
return -EINVAL;
map_def->parts |= MAP_DEF_MAX_ENTRIES;
} else if (strcmp(name, "map_flags") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
return -EINVAL;
map_def->parts |= MAP_DEF_MAP_FLAGS;
} else if (strcmp(name, "numa_node") == 0) {
if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
return -EINVAL;
map_def->parts |= MAP_DEF_NUMA_NODE;
} else if (strcmp(name, "key_size") == 0) {
__u32 sz;
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %u.\n",
map_name, map_def->key_size, sz);
return -EINVAL;
}
map_def->key_size = sz;
map_def->parts |= MAP_DEF_KEY_SIZE;
} else if (strcmp(name, "key") == 0) {
__s64 sz;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': key type [%d] not found.\n",
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': key spec is not PTR: %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
map_name, t->type, (ssize_t)sz);
return sz;
}
if (map_def->key_size && map_def->key_size != sz) {
pr_warn("map '%s': conflicting key size %u != %zd.\n",
map_name, map_def->key_size, (ssize_t)sz);
return -EINVAL;
}
map_def->key_size = sz;
map_def->key_type_id = t->type;
map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
} else if (strcmp(name, "value_size") == 0) {
__u32 sz;
if (!get_map_field_int(map_name, btf, m, &sz))
return -EINVAL;
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %u.\n",
map_name, map_def->value_size, sz);
return -EINVAL;
}
map_def->value_size = sz;
map_def->parts |= MAP_DEF_VALUE_SIZE;
} else if (strcmp(name, "value") == 0) {
__s64 sz;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': value type [%d] not found.\n",
map_name, m->type);
return -EINVAL;
}
if (!btf_is_ptr(t)) {
pr_warn("map '%s': value spec is not PTR: %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
sz = btf__resolve_size(btf, t->type);
if (sz < 0) {
pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
map_name, t->type, (ssize_t)sz);
return sz;
}
if (map_def->value_size && map_def->value_size != sz) {
pr_warn("map '%s': conflicting value size %u != %zd.\n",
map_name, map_def->value_size, (ssize_t)sz);
return -EINVAL;
}
map_def->value_size = sz;
map_def->value_type_id = t->type;
map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
}
else if (strcmp(name, "values") == 0) {
bool is_map_in_map = bpf_map_type__is_map_in_map(map_def->map_type);
bool is_prog_array = map_def->map_type == BPF_MAP_TYPE_PROG_ARRAY;
const char *desc = is_map_in_map ? "map-in-map inner" : "prog-array value";
char inner_map_name[128];
int err;
if (is_inner) {
pr_warn("map '%s': multi-level inner maps not supported.\n",
map_name);
return -ENOTSUP;
}
if (i != vlen - 1) {
pr_warn("map '%s': '%s' member should be last.\n",
map_name, name);
return -EINVAL;
}
if (!is_map_in_map && !is_prog_array) {
pr_warn("map '%s': should be map-in-map or prog-array.\n",
map_name);
return -ENOTSUP;
}
if (map_def->value_size && map_def->value_size != 4) {
pr_warn("map '%s': conflicting value size %u != 4.\n",
map_name, map_def->value_size);
return -EINVAL;
}
map_def->value_size = 4;
t = btf__type_by_id(btf, m->type);
if (!t) {
pr_warn("map '%s': %s type [%d] not found.\n",
map_name, desc, m->type);
return -EINVAL;
}
if (!btf_is_array(t) || btf_array(t)->nelems) {
pr_warn("map '%s': %s spec is not a zero-sized array.\n",
map_name, desc);
return -EINVAL;
}
t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
if (!btf_is_ptr(t)) {
pr_warn("map '%s': %s def is of unexpected kind %s.\n",
map_name, desc, btf_kind_str(t));
return -EINVAL;
}
t = skip_mods_and_typedefs(btf, t->type, NULL);
if (is_prog_array) {
if (!btf_is_func_proto(t)) {
pr_warn("map '%s': prog-array value def is of unexpected kind %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
continue;
}
if (!btf_is_struct(t)) {
pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
map_name, btf_kind_str(t));
return -EINVAL;
}
snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
if (err)
return err;
map_def->parts |= MAP_DEF_INNER_MAP;
} else if (strcmp(name, "pinning") == 0) {
__u32 val;
if (is_inner) {
pr_warn("map '%s': inner def can't be pinned.\n", map_name);
return -EINVAL;
}
if (!get_map_field_int(map_name, btf, m, &val))
return -EINVAL;
if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
pr_warn("map '%s': invalid pinning value %u.\n",
map_name, val);
return -EINVAL;
}
map_def->pinning = val;
map_def->parts |= MAP_DEF_PINNING;
} else if (strcmp(name, "map_extra") == 0) {
__u64 map_extra;
if (!get_map_field_long(map_name, btf, m, &map_extra))
return -EINVAL;
map_def->map_extra = map_extra;
map_def->parts |= MAP_DEF_MAP_EXTRA;
} else {
if (strict) {
pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
return -ENOTSUP;
}
pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
}
}
if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
pr_warn("map '%s': map type isn't specified.\n", map_name);
return -EINVAL;
}
return 0;
}
static size_t adjust_ringbuf_sz(size_t sz)
{
__u32 page_sz = sysconf(_SC_PAGE_SIZE);
__u32 mul;
/* if user forgot to set any size, make sure they see error */
if (sz == 0)
return 0;
/* Kernel expects BPF_MAP_TYPE_RINGBUF's max_entries to be
* a power-of-2 multiple of kernel's page size. If user diligently
* satisified these conditions, pass the size through.
*/
if ((sz % page_sz) == 0 && is_pow_of_2(sz / page_sz))
return sz;
/* Otherwise find closest (page_sz * power_of_2) product bigger than
* user-set size to satisfy both user size request and kernel
* requirements and substitute correct max_entries for map creation.
*/
for (mul = 1; mul <= UINT_MAX / page_sz; mul <<= 1) {
if (mul * page_sz > sz)
return mul * page_sz;
}
/* if it's impossible to satisfy the conditions (i.e., user size is
* very close to UINT_MAX but is not a power-of-2 multiple of
* page_size) then just return original size and let kernel reject it
*/
return sz;
}
static bool map_is_ringbuf(const struct bpf_map *map)
{
return map->def.type == BPF_MAP_TYPE_RINGBUF ||
map->def.type == BPF_MAP_TYPE_USER_RINGBUF;
}
static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
{
map->def.type = def->map_type;
map->def.key_size = def->key_size;
map->def.value_size = def->value_size;
map->def.max_entries = def->max_entries;
map->def.map_flags = def->map_flags;
map->map_extra = def->map_extra;
map->numa_node = def->numa_node;
map->btf_key_type_id = def->key_type_id;
map->btf_value_type_id = def->value_type_id;
/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
if (map_is_ringbuf(map))
map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
if (def->parts & MAP_DEF_MAP_TYPE)
pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
if (def->parts & MAP_DEF_KEY_TYPE)
pr_debug("map '%s': found key [%u], sz = %u.\n",
map->name, def->key_type_id, def->key_size);
else if (def->parts & MAP_DEF_KEY_SIZE)
pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
if (def->parts & MAP_DEF_VALUE_TYPE)
pr_debug("map '%s': found value [%u], sz = %u.\n",
map->name, def->value_type_id, def->value_size);
else if (def->parts & MAP_DEF_VALUE_SIZE)
pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
if (def->parts & MAP_DEF_MAX_ENTRIES)
pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
if (def->parts & MAP_DEF_MAP_FLAGS)
pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
if (def->parts & MAP_DEF_MAP_EXTRA)
pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
(unsigned long long)def->map_extra);
if (def->parts & MAP_DEF_PINNING)
pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
if (def->parts & MAP_DEF_NUMA_NODE)
pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
if (def->parts & MAP_DEF_INNER_MAP)
pr_debug("map '%s': found inner map definition.\n", map->name);
}
static const char *btf_var_linkage_str(__u32 linkage)
{
switch (linkage) {
case BTF_VAR_STATIC: return "static";
case BTF_VAR_GLOBAL_ALLOCATED: return "global";
case BTF_VAR_GLOBAL_EXTERN: return "extern";
default: return "unknown";
}
}
static int bpf_object__init_user_btf_map(struct bpf_object *obj,
const struct btf_type *sec,
int var_idx, int sec_idx,
const Elf_Data *data, bool strict,
const char *pin_root_path)
{
struct btf_map_def map_def = {}, inner_def = {};
const struct btf_type *var, *def;
const struct btf_var_secinfo *vi;
const struct btf_var *var_extra;
const char *map_name;
struct bpf_map *map;
int err;
vi = btf_var_secinfos(sec) + var_idx;
var = btf__type_by_id(obj->btf, vi->type);
var_extra = btf_var(var);
map_name = btf__name_by_offset(obj->btf, var->name_off);
if (map_name == NULL || map_name[0] == '\0') {
pr_warn("map #%d: empty name.\n", var_idx);
return -EINVAL;
}
if ((__u64)vi->offset + vi->size > data->d_size) {
pr_warn("map '%s' BTF data is corrupted.\n", map_name);
return -EINVAL;
}
if (!btf_is_var(var)) {
pr_warn("map '%s': unexpected var kind %s.\n",
map_name, btf_kind_str(var));
return -EINVAL;
}
if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
pr_warn("map '%s': unsupported map linkage %s.\n",
map_name, btf_var_linkage_str(var_extra->linkage));
return -EOPNOTSUPP;
}
def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
if (!btf_is_struct(def)) {
pr_warn("map '%s': unexpected def kind %s.\n",
map_name, btf_kind_str(var));
return -EINVAL;
}
if (def->size > vi->size) {
pr_warn("map '%s': invalid def size.\n", map_name);
return -EINVAL;
}
map = bpf_object__add_map(obj);
if (IS_ERR(map))
return PTR_ERR(map);
map->name = strdup(map_name);
if (!map->name) {
pr_warn("map '%s': failed to alloc map name.\n", map_name);
return -ENOMEM;
}
map->libbpf_type = LIBBPF_MAP_UNSPEC;
map->def.type = BPF_MAP_TYPE_UNSPEC;
map->sec_idx = sec_idx;
map->sec_offset = vi->offset;
map->btf_var_idx = var_idx;
pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
map_name, map->sec_idx, map->sec_offset);
err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
if (err)
return err;
fill_map_from_def(map, &map_def);
if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
err = build_map_pin_path(map, pin_root_path);
if (err) {
pr_warn("map '%s': couldn't build pin path.\n", map->name);
return err;
}
}
if (map_def.parts & MAP_DEF_INNER_MAP) {
map->inner_map = calloc(1, sizeof(*map->inner_map));
if (!map->inner_map)
return -ENOMEM;
map->inner_map->fd = create_placeholder_fd();
if (map->inner_map->fd < 0)
return map->inner_map->fd;
map->inner_map->sec_idx = sec_idx;
map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
if (!map->inner_map->name)
return -ENOMEM;
sprintf(map->inner_map->name, "%s.inner", map_name);
fill_map_from_def(map->inner_map, &inner_def);
}
err = map_fill_btf_type_info(obj, map);
if (err)
return err;
return 0;
}
static int init_arena_map_data(struct bpf_object *obj, struct bpf_map *map,
const char *sec_name, int sec_idx,
void *data, size_t data_sz)
{
const long page_sz = sysconf(_SC_PAGE_SIZE);
size_t mmap_sz;
mmap_sz = bpf_map_mmap_sz(obj->arena_map);
if (roundup(data_sz, page_sz) > mmap_sz) {
pr_warn("elf: sec '%s': declared ARENA map size (%zu) is too small to hold global __arena variables of size %zu\n",
sec_name, mmap_sz, data_sz);
return -E2BIG;
}
obj->arena_data = malloc(data_sz);
if (!obj->arena_data)
return -ENOMEM;
memcpy(obj->arena_data, data, data_sz);
obj->arena_data_sz = data_sz;
/* make bpf_map__init_value() work for ARENA maps */
map->mmaped = obj->arena_data;
return 0;
}
static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
const char *pin_root_path)
{
const struct btf_type *sec = NULL;
int nr_types, i, vlen, err;
const struct btf_type *t;
const char *name;
Elf_Data *data;
Elf_Scn *scn;
if (obj->efile.btf_maps_shndx < 0)
return 0;
scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
data = elf_sec_data(obj, scn);
if (!scn || !data) {
pr_warn("elf: failed to get %s map definitions for %s\n",
MAPS_ELF_SEC, obj->path);
return -EINVAL;
}
nr_types = btf__type_cnt(obj->btf);
for (i = 1; i < nr_types; i++) {
t = btf__type_by_id(obj->btf, i);
if (!btf_is_datasec(t))
continue;
name = btf__name_by_offset(obj->btf, t->name_off);
if (strcmp(name, MAPS_ELF_SEC) == 0) {
sec = t;
obj->efile.btf_maps_sec_btf_id = i;
break;
}
}
if (!sec) {
pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
return -ENOENT;
}
vlen = btf_vlen(sec);
for (i = 0; i < vlen; i++) {
err = bpf_object__init_user_btf_map(obj, sec, i,
obj->efile.btf_maps_shndx,
data, strict,
pin_root_path);
if (err)
return err;
}
for (i = 0; i < obj->nr_maps; i++) {
struct bpf_map *map = &obj->maps[i];
if (map->def.type != BPF_MAP_TYPE_ARENA)
continue;
if (obj->arena_map) {
pr_warn("map '%s': only single ARENA map is supported (map '%s' is also ARENA)\n",
map->name, obj->arena_map->name);
return -EINVAL;
}
obj->arena_map = map;
if (obj->efile.arena_data) {
err = init_arena_map_data(obj, map, ARENA_SEC, obj->efile.arena_data_shndx,
obj->efile.arena_data->d_buf,
obj->efile.arena_data->d_size);
if (err)
return err;
}
}
if (obj->efile.arena_data && !obj->arena_map) {
pr_warn("elf: sec '%s': to use global __arena variables the ARENA map should be explicitly declared in SEC(\".maps\")\n",
ARENA_SEC);
return -ENOENT;
}
return 0;
}
static int bpf_object__init_maps(struct bpf_object *obj,
const struct bpf_object_open_opts *opts)
{
const char *pin_root_path;
bool strict;
int err = 0;
strict = !OPTS_GET(opts, relaxed_maps, false);
pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
err = err ?: bpf_object__init_global_data_maps(obj);
err = err ?: bpf_object__init_kconfig_map(obj);
err = err ?: bpf_object_init_struct_ops(obj);
return err;
}
static bool section_have_execinstr(struct bpf_object *obj, int idx)
{
Elf64_Shdr *sh;
sh = elf_sec_hdr(obj, elf_sec_by_idx(obj, idx));
if (!sh)
return false;
return sh->sh_flags & SHF_EXECINSTR;
}
static bool starts_with_qmark(const char *s)
{
return s && s[0] == '?';
}
static bool btf_needs_sanitization(struct bpf_object *obj)
{
bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC);
return !has_func || !has_datasec || !has_func_global || !has_float ||
!has_decl_tag || !has_type_tag || !has_enum64 || !has_qmark_datasec;
}
static int bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
{
bool has_func_global = kernel_supports(obj, FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(obj, FEAT_BTF_DATASEC);
bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);
bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);
bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);
bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);
bool has_enum64 = kernel_supports(obj, FEAT_BTF_ENUM64);
bool has_qmark_datasec = kernel_supports(obj, FEAT_BTF_QMARK_DATASEC);
int enum64_placeholder_id = 0;
struct btf_type *t;
int i, j, vlen;
for (i = 1; i < btf__type_cnt(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
if ((!has_datasec && btf_is_var(t)) || (!has_decl_tag && btf_is_decl_tag(t))) {
/* replace VAR/DECL_TAG with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
/*
* using size = 1 is the safest choice, 4 will be too
* big and cause kernel BTF validation failure if
* original variable took less than 4 bytes
*/
t->size = 1;
*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
} else if (!has_datasec && btf_is_datasec(t)) {
/* replace DATASEC with STRUCT */
const struct btf_var_secinfo *v = btf_var_secinfos(t);
struct btf_member *m = btf_members(t);
struct btf_type *vt;
char *name;
name = (char *)btf__name_by_offset(btf, t->name_off);
while (*name) {
if (*name == '.' || *name == '?')
*name = '_';
name++;
}
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
for (j = 0; j < vlen; j++, v++, m++) {
/* order of field assignments is important */
m->offset = v->offset * 8;
m->type = v->type;
/* preserve variable name as member name */
vt = (void *)btf__type_by_id(btf, v->type);
m->name_off = vt->name_off;
}
} else if (!has_qmark_datasec && btf_is_datasec(t) &&
starts_with_qmark(btf__name_by_offset(btf, t->name_off))) {
/* replace '?' prefix with '_' for DATASEC names */
char *name;
name = (char *)btf__name_by_offset(btf, t->name_off);
if (name[0] == '?')
name[0] = '_';
} else if (!has_func && btf_is_func_proto(t)) {
/* replace FUNC_PROTO with ENUM */
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
t->size = sizeof(__u32); /* kernel enforced */
} else if (!has_func && btf_is_func(t)) {
/* replace FUNC with TYPEDEF */
t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
} else if (!has_func_global && btf_is_func(t)) {
/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
} else if (!has_float && btf_is_float(t)) {
/* replace FLOAT with an equally-sized empty STRUCT;
* since C compilers do not accept e.g. "float" as a
* valid struct name, make it anonymous
*/
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
} else if (!has_type_tag && btf_is_type_tag(t)) {
/* replace TYPE_TAG with a CONST */
t->name_off = 0;
t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
} else if (!has_enum64 && btf_is_enum(t)) {
/* clear the kflag */
t->info = btf_type_info(btf_kind(t), btf_vlen(t), false);
} else if (!has_enum64 && btf_is_enum64(t)) {
/* replace ENUM64 with a union */
struct btf_member *m;
if (enum64_placeholder_id == 0) {
enum64_placeholder_id = btf__add_int(btf, "enum64_placeholder", 1, 0);
if (enum64_placeholder_id < 0)
return enum64_placeholder_id;
t = (struct btf_type *)btf__type_by_id(btf, i);
}
m = btf_members(t);
vlen = btf_vlen(t);
t->info = BTF_INFO_ENC(BTF_KIND_UNION, 0, vlen);
for (j = 0; j < vlen; j++, m++) {
m->type = enum64_placeholder_id;
m->offset = 0;
}
}
}
return 0;
}
static bool libbpf_needs_btf(const struct bpf_object *obj)
{
return obj->efile.btf_maps_shndx >= 0 ||
obj->efile.has_st_ops ||
obj->nr_extern > 0;
}
static bool kernel_needs_btf(const struct bpf_object *obj)
{
return obj->efile.has_st_ops;
}
static int bpf_object__init_btf(struct bpf_object *obj,
Elf_Data *btf_data,
Elf_Data *btf_ext_data)
{
int err = -ENOENT;
if (btf_data) {
obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
err = libbpf_get_error(obj->btf);
if (err) {
obj->btf = NULL;
pr_warn("Error loading ELF section %s: %s.\n", BTF_ELF_SEC, errstr(err));
goto out;
}
/* enforce 8-byte pointers for BPF-targeted BTFs */
btf__set_pointer_size(obj->btf, 8);
}
if (btf_ext_data) {
struct btf_ext_info *ext_segs[3];
int seg_num, sec_num;
if (!obj->btf) {
pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
BTF_EXT_ELF_SEC, BTF_ELF_SEC);
goto out;
}
obj->btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
err = libbpf_get_error(obj->btf_ext);
if (err) {
pr_warn("Error loading ELF section %s: %s. Ignored and continue.\n",
BTF_EXT_ELF_SEC, errstr(err));
obj->btf_ext = NULL;
goto out;
}
/* setup .BTF.ext to ELF section mapping */
ext_segs[0] = &obj->btf_ext->func_info;
ext_segs[1] = &obj->btf_ext->line_info;
ext_segs[2] = &obj->btf_ext->core_relo_info;
for (seg_num = 0; seg_num < ARRAY_SIZE(ext_segs); seg_num++) {
struct btf_ext_info *seg = ext_segs[seg_num];
const struct btf_ext_info_sec *sec;
const char *sec_name;
Elf_Scn *scn;
if (seg->sec_cnt == 0)
continue;
seg->sec_idxs = calloc(seg->sec_cnt, sizeof(*seg->sec_idxs));
if (!seg->sec_idxs) {
err = -ENOMEM;
goto out;
}
sec_num = 0;
for_each_btf_ext_sec(seg, sec) {
/* preventively increment index to avoid doing
* this before every continue below
*/
sec_num++;
sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
if (str_is_empty(sec_name))
continue;
scn = elf_sec_by_name(obj, sec_name);
if (!scn)
continue;
seg->sec_idxs[sec_num - 1] = elf_ndxscn(scn);
}
}
}
out:
if (err && libbpf_needs_btf(obj)) {
pr_warn("BTF is required, but is missing or corrupted.\n");
return err;
}
return 0;
}
static int compare_vsi_off(const void *_a, const void *_b)
{
const struct btf_var_secinfo *a = _a;
const struct btf_var_secinfo *b = _b;
return a->offset - b->offset;
}
static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
struct btf_type *t)
{
__u32 size = 0, i, vars = btf_vlen(t);
const char *sec_name = btf__name_by_offset(btf, t->name_off);
struct btf_var_secinfo *vsi;
bool fixup_offsets = false;
int err;
if (!sec_name) {
pr_debug("No name found in string section for DATASEC kind.\n");
return -ENOENT;
}
/* Extern-backing datasecs (.ksyms, .kconfig) have their size and
* variable offsets set at the previous step. Further, not every
* extern BTF VAR has corresponding ELF symbol preserved, so we skip
* all fixups altogether for such sections and go straight to sorting
* VARs within their DATASEC.
*/
if (strcmp(sec_name, KCONFIG_SEC) == 0 || strcmp(sec_name, KSYMS_SEC) == 0)
goto sort_vars;
/* Clang leaves DATASEC size and VAR offsets as zeroes, so we need to
* fix this up. But BPF static linker already fixes this up and fills
* all the sizes and offsets during static linking. So this step has
* to be optional. But the STV_HIDDEN handling is non-optional for any
* non-extern DATASEC, so the variable fixup loop below handles both
* functions at the same time, paying the cost of BTF VAR <-> ELF
* symbol matching just once.
*/
if (t->size == 0) {
err = find_elf_sec_sz(obj, sec_name, &size);
if (err || !size) {
pr_debug("sec '%s': failed to determine size from ELF: size %u, err %s\n",
sec_name, size, errstr(err));
return -ENOENT;
}
t->size = size;
fixup_offsets = true;
}
for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
const struct btf_type *t_var;
struct btf_var *var;
const char *var_name;
Elf64_Sym *sym;
t_var = btf__type_by_id(btf, vsi->type);
if (!t_var || !btf_is_var(t_var)) {
pr_debug("sec '%s': unexpected non-VAR type found\n", sec_name);
return -EINVAL;
}
var = btf_var(t_var);
if (var->linkage == BTF_VAR_STATIC || var->linkage == BTF_VAR_GLOBAL_EXTERN)
continue;
var_name = btf__name_by_offset(btf, t_var->name_off);
if (!var_name) {
pr_debug("sec '%s': failed to find name of DATASEC's member #%d\n",
sec_name, i);
return -ENOENT;
}
sym = find_elf_var_sym(obj, var_name);
if (IS_ERR(sym)) {
pr_debug("sec '%s': failed to find ELF symbol for VAR '%s'\n",
sec_name, var_name);
return -ENOENT;
}
if (fixup_offsets)
vsi->offset = sym->st_value;
/* if variable is a global/weak symbol, but has restricted
* (STV_HIDDEN or STV_INTERNAL) visibility, mark its BTF VAR
* as static. This follows similar logic for functions (BPF
* subprogs) and influences libbpf's further decisions about
* whether to make global data BPF array maps as
* BPF_F_MMAPABLE.
*/
if (ELF64_ST_VISIBILITY(sym->st_other) == STV_HIDDEN
|| ELF64_ST_VISIBILITY(sym->st_other) == STV_INTERNAL)
var->linkage = BTF_VAR_STATIC;
}
sort_vars:
qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
return 0;
}
static int bpf_object_fixup_btf(struct bpf_object *obj)
{
int i, n, err = 0;
if (!obj->btf)
return 0;
n = btf__type_cnt(obj->btf);
for (i = 1; i < n; i++) {
struct btf_type *t = btf_type_by_id(obj->btf, i);
/* Loader needs to fix up some of the things compiler
* couldn't get its hands on while emitting BTF. This
* is section size and global variable offset. We use
* the info from the ELF itself for this purpose.
*/
if (btf_is_datasec(t)) {
err = btf_fixup_datasec(obj, obj->btf, t);
if (err)
return err;
}
}
return 0;
}
static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
{
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
prog->type == BPF_PROG_TYPE_LSM)
return true;
/* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
* also need vmlinux BTF
*/
if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
return true;
return false;
}
static bool map_needs_vmlinux_btf(struct bpf_map *map)
{
return bpf_map__is_struct_ops(map);
}
static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
{
struct bpf_program *prog;
struct bpf_map *map;
int i;
/* CO-RE relocations need kernel BTF, only when btf_custom_path
* is not specified
*/
if (obj->btf_ext && obj->btf_ext->core_relo_info.len && !obj->btf_custom_path)
return true;
/* Support for typed ksyms needs kernel BTF */
for (i = 0; i < obj->nr_extern; i++) {
const struct extern_desc *ext;
ext = &obj->externs[i];
if (ext->type == EXT_KSYM && ext->ksym.type_id)
return true;
}
bpf_object__for_each_program(prog, obj) {
if (!prog->autoload)
continue;
if (prog_needs_vmlinux_btf(prog))
return true;
}
bpf_object__for_each_map(map, obj) {
if (map_needs_vmlinux_btf(map))
return true;
}
return false;
}
static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
{
int err;
/* btf_vmlinux could be loaded earlier */
if (obj->btf_vmlinux || obj->gen_loader)
return 0;
if (!force && !obj_needs_vmlinux_btf(obj))
return 0;
obj->btf_vmlinux = btf__load_vmlinux_btf();
err = libbpf_get_error(obj->btf_vmlinux);
if (err) {
pr_warn("Error loading vmlinux BTF: %s\n", errstr(err));
obj->btf_vmlinux = NULL;
return err;
}
return 0;
}
static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
{
struct btf *kern_btf = obj->btf;
bool btf_mandatory, sanitize;
int i, err = 0;
if (!obj->btf)
return 0;
if (!kernel_supports(obj, FEAT_BTF)) {
if (kernel_needs_btf(obj)) {
err = -EOPNOTSUPP;
goto report;
}
pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
return 0;
}
/* Even though some subprogs are global/weak, user might prefer more
* permissive BPF verification process that BPF verifier performs for
* static functions, taking into account more context from the caller
* functions. In such case, they need to mark such subprogs with
* __attribute__((visibility("hidden"))) and libbpf will adjust
* corresponding FUNC BTF type to be marked as static and trigger more
* involved BPF verification process.
*/
for (i = 0; i < obj->nr_programs; i++) {
struct bpf_program *prog = &obj->programs[i];
struct btf_type *t;
const char *name;
int j, n;
if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
continue;
n = btf__type_cnt(obj->btf);
for (j = 1; j < n; j++) {
t = btf_type_by_id(obj->btf, j);
if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
continue;
name = btf__str_by_offset(obj->btf, t->name_off);
if (strcmp(name, prog->name) != 0)
continue;
t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
break;
}
}
sanitize = btf_needs_sanitization(obj);
if (sanitize) {
const void *raw_data;
__u32 sz;
/* clone BTF to sanitize a copy and leave the original intact */
raw_data = btf__raw_data(obj->btf, &sz);
kern_btf = btf__new(raw_data, sz);
err = libbpf_get_error(kern_btf);
if (err)
return err;
/* enforce 8-byte pointers for BPF-targeted BTFs */
btf__set_pointer_size(obj->btf, 8);
err = bpf_object__sanitize_btf(obj, kern_btf);
if (err)
return err;
}
if (obj->gen_loader) {
__u32 raw_size = 0;
const void *raw_data = btf__raw_data(kern_btf, &raw_size);
if (!raw_data)
return -ENOMEM;
bpf_gen__load_btf(obj->gen_loader, raw_data, raw_size);
/* Pretend to have valid FD to pass various fd >= 0 checks.
* This fd == 0 will not be used with any syscall and will be reset to -1 eventually.
*/
btf__set_fd(kern_btf, 0);
} else {
/* currently BPF_BTF_LOAD only supports log_level 1 */
err = btf_load_into_kernel(kern_btf, obj->log_buf, obj->log_size,
obj->log_level ? 1 : 0, obj->token_fd);
}
if (sanitize) {
if (!err) {
/* move fd to libbpf's BTF */
btf__set_fd(obj->btf, btf__fd(kern_btf));
btf__set_fd(kern_btf, -1);
}
btf__free(kern_btf);
}
report:
if (err) {
btf_mandatory = kernel_needs_btf(obj);
if (btf_mandatory) {
pr_warn("Error loading .BTF into kernel: %s. BTF is mandatory, can't proceed.\n",
errstr(err));
} else {
pr_info("Error loading .BTF into kernel: %s. BTF is optional, ignoring.\n",
errstr(err));
err = 0;
}
}
return err;
}
static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
{
const char *name;
name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
if (!name) {
pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
off, obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
{
const char *name;
name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
if (!name) {
pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
off, obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
{
Elf_Scn *scn;
scn = elf_getscn(obj->efile.elf, idx);
if (!scn) {
pr_warn("elf: failed to get section(%zu) from %s: %s\n",
idx, obj->path, elf_errmsg(-1));
return NULL;
}
return scn;
}
static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
{
Elf_Scn *scn = NULL;
Elf *elf = obj->efile.elf;
const char *sec_name;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
sec_name = elf_sec_name(obj, scn);
if (!sec_name)
return NULL;
if (strcmp(sec_name, name) != 0)
continue;
return scn;
}
return NULL;
}
static Elf64_Shdr *elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn)
{
Elf64_Shdr *shdr;
if (!scn)
return NULL;
shdr = elf64_getshdr(scn);
if (!shdr) {
pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
elf_ndxscn(scn), obj->path, elf_errmsg(-1));
return NULL;
}
return shdr;
}
static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
{
const char *name;
Elf64_Shdr *sh;
if (!scn)
return NULL;
sh = elf_sec_hdr(obj, scn);
if (!sh)
return NULL;
name = elf_sec_str(obj, sh->sh_name);
if (!name) {
pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
elf_ndxscn(scn), obj->path, elf_errmsg(-1));
return NULL;
}
return name;
}
static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
{
Elf_Data *data;
if (!scn)
return NULL;
data = elf_getdata(scn, 0);
if (!data) {
pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
obj->path, elf_errmsg(-1));
return NULL;
}
return data;
}
static Elf64_Sym *elf_sym_by_idx(const struct bpf_object *obj, size_t idx)
{
if (idx >= obj->efile.symbols->d_size / sizeof(Elf64_Sym))
return NULL;
return (Elf64_Sym *)obj->efile.symbols->d_buf + idx;
}
static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
{
if (idx >= data->d_size / sizeof(Elf64_Rel))
return NULL;
return (Elf64_Rel *)data->d_buf + idx;
}
static bool is_sec_name_dwarf(const char *name)
{
/* approximation, but the actual list is too long */
return str_has_pfx(name, ".debug_");
}
static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)
{
/* no special handling of .strtab */
if (hdr->sh_type == SHT_STRTAB)
return true;
/* ignore .llvm_addrsig section as well */
if (hdr->sh_type == SHT_LLVM_ADDRSIG)
return true;
/* no subprograms will lead to an empty .text section, ignore it */
if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
strcmp(name, ".text") == 0)
return true;
/* DWARF sections */
if (is_sec_name_dwarf(name))
return true;
if (str_has_pfx(name, ".rel")) {
name += sizeof(".rel") - 1;
/* DWARF section relocations */
if (is_sec_name_dwarf(name))
return true;
/* .BTF and .BTF.ext don't need relocations */
if (strcmp(name, BTF_ELF_SEC) == 0 ||
strcmp(name, BTF_EXT_ELF_SEC) == 0)
return true;
}
return false;
}
static int cmp_progs(const void *_a, const void *_b)
{
const struct bpf_program *a = _a;
const struct bpf_program *b = _b;
if (a->sec_idx != b->sec_idx)
return a->sec_idx < b->sec_idx ? -1 : 1;
/* sec_insn_off can't be the same within the section */
return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
}
static int bpf_object__elf_collect(struct bpf_object *obj)
{
struct elf_sec_desc *sec_desc;
Elf *elf = obj->efile.elf;
Elf_Data *btf_ext_data = NULL;
Elf_Data *btf_data = NULL;
int idx = 0, err = 0;
const char *name;
Elf_Data *data;
Elf_Scn *scn;
Elf64_Shdr *sh;
/* ELF section indices are 0-based, but sec #0 is special "invalid"
* section. Since section count retrieved by elf_getshdrnum() does
* include sec #0, it is already the necessary size of an array to keep
* all the sections.
*/
if (elf_getshdrnum(obj->efile.elf, &obj->efile.sec_cnt)) {
pr_warn("elf: failed to get the number of sections for %s: %s\n",
obj->path, elf_errmsg(-1));
return -LIBBPF_ERRNO__FORMAT;
}
obj->efile.secs = calloc(obj->efile.sec_cnt, sizeof(*obj->efile.secs));
if (!obj->efile.secs)
return -ENOMEM;
/* a bunch of ELF parsing functionality depends on processing symbols,
* so do the first pass and find the symbol table
*/
scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
sh = elf_sec_hdr(obj, scn);
if (!sh)
return -LIBBPF_ERRNO__FORMAT;
if (sh->sh_type == SHT_SYMTAB) {
if (obj->efile.symbols) {
pr_warn("elf: multiple symbol tables in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
data = elf_sec_data(obj, scn);
if (!data)
return -LIBBPF_ERRNO__FORMAT;
idx = elf_ndxscn(scn);
obj->efile.symbols = data;
obj->efile.symbols_shndx = idx;
obj->efile.strtabidx = sh->sh_link;
}
}
if (!obj->efile.symbols) {
pr_warn("elf: couldn't find symbol table in %s, stripped object file?\n",
obj->path);
return -ENOENT;
}
scn = NULL;
while ((scn = elf_nextscn(elf, scn)) != NULL) {
idx = elf_ndxscn(scn);
sec_desc = &obj->efile.secs[idx];
sh = elf_sec_hdr(obj, scn);
if (!sh)
return -LIBBPF_ERRNO__FORMAT;
name = elf_sec_str(obj, sh->sh_name);
if (!name)
return -LIBBPF_ERRNO__FORMAT;
if (ignore_elf_section(sh, name))
continue;
data = elf_sec_data(obj, scn);
if (!data)
return -LIBBPF_ERRNO__FORMAT;
pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
idx, name, (unsigned long)data->d_size,
(int)sh->sh_link, (unsigned long)sh->sh_flags,
(int)sh->sh_type);
if (strcmp(name, "license") == 0) {
err = bpf_object__init_license(obj, data->d_buf, data->d_size);
if (err)
return err;
} else if (strcmp(name, "version") == 0) {
err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
if (err)
return err;
} else if (strcmp(name, "maps") == 0) {
pr_warn("elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+\n");
return -ENOTSUP;
} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
obj->efile.btf_maps_shndx = idx;
} else if (strcmp(name, BTF_ELF_SEC) == 0) {
if (sh->sh_type != SHT_PROGBITS)
return -LIBBPF_ERRNO__FORMAT;
btf_data = data;
} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
if (sh->sh_type != SHT_PROGBITS)
return -LIBBPF_ERRNO__FORMAT;
btf_ext_data = data;
} else if (sh->sh_type == SHT_SYMTAB) {
/* already processed during the first pass above */
} else if (sh->sh_type == SHT_PROGBITS && data->d_size > 0) {
if (sh->sh_flags & SHF_EXECINSTR) {
if (strcmp(name, ".text") == 0)
obj->efile.text_shndx = idx;
err = bpf_object__add_programs(obj, data, name, idx);
if (err)
return err;
} else if (strcmp(name, DATA_SEC) == 0 ||
str_has_pfx(name, DATA_SEC ".")) {
sec_desc->sec_type = SEC_DATA;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (strcmp(name, RODATA_SEC) == 0 ||
str_has_pfx(name, RODATA_SEC ".")) {
sec_desc->sec_type = SEC_RODATA;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (strcmp(name, STRUCT_OPS_SEC) == 0 ||
strcmp(name, STRUCT_OPS_LINK_SEC) == 0 ||
strcmp(name, "?" STRUCT_OPS_SEC) == 0 ||
strcmp(name, "?" STRUCT_OPS_LINK_SEC) == 0) {
sec_desc->sec_type = SEC_ST_OPS;
sec_desc->shdr = sh;
sec_desc->data = data;
obj->efile.has_st_ops = true;
} else if (strcmp(name, ARENA_SEC) == 0) {
obj->efile.arena_data = data;
obj->efile.arena_data_shndx = idx;
} else {
pr_info("elf: skipping unrecognized data section(%d) %s\n",
idx, name);
}
} else if (sh->sh_type == SHT_REL) {
int targ_sec_idx = sh->sh_info; /* points to other section */
if (sh->sh_entsize != sizeof(Elf64_Rel) ||
targ_sec_idx >= obj->efile.sec_cnt)
return -LIBBPF_ERRNO__FORMAT;
/* Only do relo for section with exec instructions */
if (!section_have_execinstr(obj, targ_sec_idx) &&
strcmp(name, ".rel" STRUCT_OPS_SEC) &&
strcmp(name, ".rel" STRUCT_OPS_LINK_SEC) &&
strcmp(name, ".rel?" STRUCT_OPS_SEC) &&
strcmp(name, ".rel?" STRUCT_OPS_LINK_SEC) &&
strcmp(name, ".rel" MAPS_ELF_SEC)) {
pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
idx, name, targ_sec_idx,
elf_sec_name(obj, elf_sec_by_idx(obj, targ_sec_idx)) ?: "<?>");
continue;
}
sec_desc->sec_type = SEC_RELO;
sec_desc->shdr = sh;
sec_desc->data = data;
} else if (sh->sh_type == SHT_NOBITS && (strcmp(name, BSS_SEC) == 0 ||
str_has_pfx(name, BSS_SEC "."))) {
sec_desc->sec_type = SEC_BSS;
sec_desc->shdr = sh;
sec_desc->data = data;
} else {
pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
(size_t)sh->sh_size);
}
}
if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
return -LIBBPF_ERRNO__FORMAT;
}
/* change BPF program insns to native endianness for introspection */
if (!is_native_endianness(obj))
bpf_object_bswap_progs(obj);
/* sort BPF programs by section name and in-section instruction offset
* for faster search
*/
if (obj->nr_programs)
qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
return bpf_object__init_btf(obj, btf_data, btf_ext_data);
}
static bool sym_is_extern(const Elf64_Sym *sym)
{
int bind = ELF64_ST_BIND(sym->st_info);
/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
return sym->st_shndx == SHN_UNDEF &&
(bind == STB_GLOBAL || bind == STB_WEAK) &&
ELF64_ST_TYPE(sym->st_info) == STT_NOTYPE;
}
static bool sym_is_subprog(const Elf64_Sym *sym, int text_shndx)
{
int bind = ELF64_ST_BIND(sym->st_info);
int type = ELF64_ST_TYPE(sym->st_info);
/* in .text section */
if (sym->st_shndx != text_shndx)
return false;
/* local function */
if (bind == STB_LOCAL && type == STT_SECTION)
return true;
/* global function */
return (bind == STB_GLOBAL || bind == STB_WEAK) && type == STT_FUNC;
}
static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
{
const struct btf_type *t;
const char *tname;
int i, n;
if (!btf)
return -ESRCH;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (!btf_is_var(t) && !btf_is_func(t))
continue;
tname = btf__name_by_offset(btf, t->name_off);
if (strcmp(tname, ext_name))
continue;
if (btf_is_var(t) &&
btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
return -EINVAL;
if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
return -EINVAL;
return i;
}
return -ENOENT;
}
static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
const struct btf_var_secinfo *vs;
const struct btf_type *t;
int i, j, n;
if (!btf)
return -ESRCH;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (!btf_is_datasec(t))
continue;
vs = btf_var_secinfos(t);
for (j = 0; j < btf_vlen(t); j++, vs++) {
if (vs->type == ext_btf_id)
return i;
}
}
return -ENOENT;
}
static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
bool *is_signed)
{
const struct btf_type *t;
const char *name;
t = skip_mods_and_typedefs(btf, id, NULL);
name = btf__name_by_offset(btf, t->name_off);
if (is_signed)
*is_signed = false;
switch (btf_kind(t)) {
case BTF_KIND_INT: {
int enc = btf_int_encoding(t);
if (enc & BTF_INT_BOOL)
return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
if (is_signed)
*is_signed = enc & BTF_INT_SIGNED;
if (t->size == 1)
return KCFG_CHAR;
if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
return KCFG_UNKNOWN;
return KCFG_INT;
}
case BTF_KIND_ENUM:
if (t->size != 4)
return KCFG_UNKNOWN;
if (strcmp(name, "libbpf_tristate"))
return KCFG_UNKNOWN;
return KCFG_TRISTATE;
case BTF_KIND_ENUM64:
if (strcmp(name, "libbpf_tristate"))
return KCFG_UNKNOWN;
return KCFG_TRISTATE;
case BTF_KIND_ARRAY:
if (btf_array(t)->nelems == 0)
return KCFG_UNKNOWN;
if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
return KCFG_UNKNOWN;
return KCFG_CHAR_ARR;
default:
return KCFG_UNKNOWN;
}
}
static int cmp_externs(const void *_a, const void *_b)
{
const struct extern_desc *a = _a;
const struct extern_desc *b = _b;
if (a->type != b->type)
return a->type < b->type ? -1 : 1;
if (a->type == EXT_KCFG) {
/* descending order by alignment requirements */
if (a->kcfg.align != b->kcfg.align)
return a->kcfg.align > b->kcfg.align ? -1 : 1;
/* ascending order by size, within same alignment class */
if (a->kcfg.sz != b->kcfg.sz)
return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
}
/* resolve ties by name */
return strcmp(a->name, b->name);
}
static int find_int_btf_id(const struct btf *btf)
{
const struct btf_type *t;
int i, n;
n = btf__type_cnt(btf);
for (i = 1; i < n; i++) {
t = btf__type_by_id(btf, i);
if (btf_is_int(t) && btf_int_bits(t) == 32)
return i;
}
return 0;
}
static int add_dummy_ksym_var(struct btf *btf)
{
int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
const struct btf_var_secinfo *vs;
const struct btf_type *sec;
if (!btf)
return 0;
sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
BTF_KIND_DATASEC);
if (sec_btf_id < 0)
return 0;
sec = btf__type_by_id(btf, sec_btf_id);
vs = btf_var_secinfos(sec);
for (i = 0; i < btf_vlen(sec); i++, vs++) {
const struct btf_type *vt;
vt = btf__type_by_id(btf, vs->type);
if (btf_is_func(vt))
break;
}
/* No func in ksyms sec. No need to add dummy var. */
if (i == btf_vlen(sec))
return 0;
int_btf_id = find_int_btf_id(btf);
dummy_var_btf_id = btf__add_var(btf,
"dummy_ksym",
BTF_VAR_GLOBAL_ALLOCATED,
int_btf_id);
if (dummy_var_btf_id < 0)
pr_warn("cannot create a dummy_ksym var\n");
return dummy_var_btf_id;
}
static int bpf_object__collect_externs(struct bpf_object *obj)
{
struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
const struct btf_type *t;
struct extern_desc *ext;
int i, n, off, dummy_var_btf_id;
const char *ext_name, *sec_name;
size_t ext_essent_len;
Elf_Scn *scn;
Elf64_Shdr *sh;
if (!obj->efile.symbols)
return 0;
scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
sh = elf_sec_hdr(obj, scn);
if (!sh || sh->sh_entsize != sizeof(Elf64_Sym))
return -LIBBPF_ERRNO__FORMAT;
dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
if (dummy_var_btf_id < 0)
return dummy_var_btf_id;
n = sh->sh_size / sh->sh_entsize;
pr_debug("looking for externs among %d symbols...\n", n);
for (i = 0; i < n; i++) {
Elf64_Sym *sym = elf_sym_by_idx(obj, i);
if (!sym)
return -LIBBPF_ERRNO__FORMAT;
if (!sym_is_extern(sym))
continue;
ext_name = elf_sym_str(obj, sym->st_name);
if (!ext_name || !ext_name[0])
continue;
ext = obj->externs;
ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
if (!ext)
return -ENOMEM;
obj->externs = ext;
ext = &ext[obj->nr_extern];
memset(ext, 0, sizeof(*ext));
obj->nr_extern++;
ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
if (ext->btf_id <= 0) {
pr_warn("failed to find BTF for extern '%s': %d\n",
ext_name, ext->btf_id);
return ext->btf_id;
}
t = btf__type_by_id(obj->btf, ext->btf_id);
ext->name = btf__name_by_offset(obj->btf, t->name_off);
ext->sym_idx = i;
ext->is_weak = ELF64_ST_BIND(sym->st_info) == STB_WEAK;
ext_essent_len = bpf_core_essential_name_len(ext->name);
ext->essent_name = NULL;
if (ext_essent_len != strlen(ext->name)) {
ext->essent_name = strndup(ext->name, ext_essent_len);
if (!ext->essent_name)
return -ENOMEM;
}
ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
if (ext->sec_btf_id <= 0) {
pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
ext_name, ext->btf_id, ext->sec_btf_id);
return ext->sec_btf_id;
}
sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
sec_name = btf__name_by_offset(obj->btf, sec->name_off);
if (strcmp(sec_name, KCONFIG_SEC) == 0) {
if (btf_is_func(t)) {
pr_warn("extern function %s is unsupported under %s section\n",
ext->name, KCONFIG_SEC);
return -ENOTSUP;
}
kcfg_sec = sec;
ext->type = EXT_KCFG;
ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
if (ext->kcfg.sz <= 0) {
pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
ext_name, ext->kcfg.sz);
return ext->kcfg.sz;
}
ext->kcfg.align = btf__align_of(obj->btf, t->type);
if (ext->kcfg.align <= 0) {
pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
ext_name, ext->kcfg.align);
return -EINVAL;
}
ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
&ext->kcfg.is_signed);
if (ext->kcfg.type == KCFG_UNKNOWN) {
pr_warn("extern (kcfg) '%s': type is unsupported\n", ext_name);
return -ENOTSUP;
}
} else if (strcmp(sec_name, KSYMS_SEC) == 0) {
ksym_sec = sec;
ext->type = EXT_KSYM;
skip_mods_and_typedefs(obj->btf, t->type,
&ext->ksym.type_id);
} else {
pr_warn("unrecognized extern section '%s'\n", sec_name);
return -ENOTSUP;
}
}
pr_debug("collected %d externs total\n", obj->nr_extern);
if (!obj->nr_extern)
return 0;
/* sort externs by type, for kcfg ones also by (align, size, name) */
qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
/* for .ksyms section, we need to turn all externs into allocated
* variables in BTF to pass kernel verification; we do this by
* pretending that each extern is a 8-byte variable
*/
if (ksym_sec) {
/* find existing 4-byte integer type in BTF to use for fake
* extern variables in DATASEC
*/
int int_btf_id = find_int_btf_id(obj->btf);
/* For extern function, a dummy_var added earlier
* will be used to replace the vs->type and
* its name string will be used to refill
* the missing param's name.
*/
const struct btf_type *dummy_var;
dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KSYM)
continue;
pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
i, ext->sym_idx, ext->name);
}
sec = ksym_sec;
n = btf_vlen(sec);
for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
struct btf_type *vt;
vt = (void *)btf__type_by_id(obj->btf, vs->type);
ext_name = btf__name_by_offset(obj->btf, vt->name_off);
ext = find_extern_by_name(obj, ext_name);
if (!ext) {
pr_warn("failed to find extern definition for BTF %s '%s'\n",
btf_kind_str(vt), ext_name);
return -ESRCH;
}
if (btf_is_func(vt)) {
const struct btf_type *func_proto;
struct btf_param *param;
int j;
func_proto = btf__type_by_id(obj->btf,
vt->type);
param = btf_params(func_proto);
/* Reuse the dummy_var string if the
* func proto does not have param name.
*/
for (j = 0; j < btf_vlen(func_proto); j++)
if (param[j].type && !param[j].name_off)
param[j].name_off =
dummy_var->name_off;
vs->type = dummy_var_btf_id;
vt->info &= ~0xffff;
vt->info |= BTF_FUNC_GLOBAL;
} else {
btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
vt->type = int_btf_id;
}
vs->offset = off;
vs->size = sizeof(int);
}
sec->size = off;
}
if (kcfg_sec) {
sec = kcfg_sec;
/* for kcfg externs calculate their offsets within a .kconfig map */
off = 0;
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
if (ext->type != EXT_KCFG)
continue;
ext->kcfg.data_off = roundup(off, ext->kcfg.align);
off = ext->kcfg.data_off + ext->kcfg.sz;
pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
i, ext->sym_idx, ext->kcfg.data_off, ext->name);
}
sec->size = off;
n = btf_vlen(sec);
for (i = 0; i < n; i++) {
struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
t = btf__type_by_id(obj->btf, vs->type);
ext_name = btf__name_by_offset(obj->btf, t->name_off);
ext = find_extern_by_name(obj, ext_name);
if (!ext) {
pr_warn("failed to find extern definition for BTF var '%s'\n",
ext_name);
return -ESRCH;
}
btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
vs->offset = ext->kcfg.data_off;
}
}
return 0;
}
static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog)
{
return prog->sec_idx == obj->efile.text_shndx;
}
struct bpf_program *
bpf_object__find_program_by_name(const struct bpf_object *obj,
const char *name)
{
struct bpf_program *prog;
bpf_object__for_each_program(prog, obj) {
if (prog_is_subprog(obj, prog))
continue;
if (!strcmp(prog->name, name))
return prog;
}
return errno = ENOENT, NULL;
}
static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
int shndx)
{
switch (obj->efile.secs[shndx].sec_type) {
case SEC_BSS:
case SEC_DATA:
case SEC_RODATA:
return true;
default:
return false;
}
}
static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
int shndx)
{
return shndx == obj->efile.btf_maps_shndx;
}
static enum libbpf_map_type
bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
{
if (shndx == obj->efile.symbols_shndx)
return LIBBPF_MAP_KCONFIG;
switch (obj->efile.secs[shndx].sec_type) {
case SEC_BSS:
return LIBBPF_MAP_BSS;
case SEC_DATA:
return LIBBPF_MAP_DATA;
case SEC_RODATA:
return LIBBPF_MAP_RODATA;
default:
return LIBBPF_MAP_UNSPEC;
}
}
static int bpf_program__record_reloc(struct bpf_program *prog,
struct reloc_desc *reloc_desc,
__u32 insn_idx, const char *sym_name,
const Elf64_Sym *sym, const Elf64_Rel *rel)
{
struct bpf_insn *insn = &prog->insns[insn_idx];
size_t map_idx, nr_maps = prog->obj->nr_maps;
struct bpf_object *obj = prog->obj;
__u32 shdr_idx = sym->st_shndx;
enum libbpf_map_type type;
const char *sym_sec_name;
struct bpf_map *map;
if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
prog->name, sym_name, insn_idx, insn->code);
return -LIBBPF_ERRNO__RELOC;
}
if (sym_is_extern(sym)) {
int sym_idx = ELF64_R_SYM(rel->r_info);
int i, n = obj->nr_extern;
struct extern_desc *ext;
for (i = 0; i < n; i++) {
ext = &obj->externs[i];
if (ext->sym_idx == sym_idx)
break;
}
if (i >= n) {
pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
prog->name, sym_name, sym_idx);
return -LIBBPF_ERRNO__RELOC;
}
pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
prog->name, i, ext->name, ext->sym_idx, insn_idx);
if (insn->code == (BPF_JMP | BPF_CALL))
reloc_desc->type = RELO_EXTERN_CALL;
else
reloc_desc->type = RELO_EXTERN_LD64;
reloc_desc->insn_idx = insn_idx;
reloc_desc->ext_idx = i;
return 0;
}
/* sub-program call relocation */
if (is_call_insn(insn)) {
if (insn->src_reg != BPF_PSEUDO_CALL) {
pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
return -LIBBPF_ERRNO__RELOC;
}
/* text_shndx can be 0, if no default "main" program exists */
if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
if (sym->st_value % BPF_INSN_SZ) {
pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
prog->name, sym_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_CALL;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
prog->name, sym_name, shdr_idx);
return -LIBBPF_ERRNO__RELOC;
}
/* loading subprog addresses */
if (sym_is_subprog(sym, obj->efile.text_shndx)) {
/* global_func: sym->st_value = offset in the section, insn->imm = 0.
* local_func: sym->st_value = 0, insn->imm = offset in the section.
*/
if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
prog->name, sym_name, (size_t)sym->st_value, insn->imm);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_SUBPROG_ADDR;
reloc_desc->insn_idx = insn_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
/* arena data relocation */
if (shdr_idx == obj->efile.arena_data_shndx) {
reloc_desc->type = RELO_DATA;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = obj->arena_map - obj->maps;
reloc_desc->sym_off = sym->st_value;
return 0;
}
/* generic map reference relocation */
if (type == LIBBPF_MAP_UNSPEC) {
if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
prog->name, sym_name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
map = &obj->maps[map_idx];
if (map->libbpf_type != type ||
map->sec_idx != sym->st_shndx ||
map->sec_offset != sym->st_value)
continue;
pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
prog->name, map_idx, map->name, map->sec_idx,
map->sec_offset, insn_idx);
break;
}
if (map_idx >= nr_maps) {
pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
prog->name, sym_sec_name, (size_t)sym->st_value);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_LD64;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = map_idx;
reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
return 0;
}
/* global data map relocation */
if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
pr_warn("prog '%s': bad data relo against section '%s'\n",
prog->name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
for (map_idx = 0; map_idx < nr_maps; map_idx++) {
map = &obj->maps[map_idx];
if (map->libbpf_type != type || map->sec_idx != sym->st_shndx)
continue;
pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
prog->name, map_idx, map->name, map->sec_idx,
map->sec_offset, insn_idx);
break;
}
if (map_idx >= nr_maps) {
pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
prog->name, sym_sec_name);
return -LIBBPF_ERRNO__RELOC;
}
reloc_desc->type = RELO_DATA;
reloc_desc->insn_idx = insn_idx;
reloc_desc->map_idx = map_idx;
reloc_desc->sym_off = sym->st_value;
return 0;
}
static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
{
return insn_idx >= prog->sec_insn_off &&
insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
}
static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
size_t sec_idx, size_t insn_idx)
{
int l = 0, r = obj->nr_programs - 1, m;
struct bpf_program *prog;
if (!obj->nr_programs)
return NULL;
while (l < r) {
m = l + (r - l + 1) / 2;
prog = &obj->programs[m];
if (prog->sec_idx < sec_idx ||
(prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
l = m;
else
r = m - 1;
}
/* matching program could be at index l, but it still might be the
* wrong one, so we need to double check conditions for the last time
*/
prog = &obj->programs[l];
if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
return prog;
return NULL;
}
static int
bpf_object__collect_prog_relos(struct bpf_object *obj, Elf64_Shdr *shdr, Elf_Data *data)
{
const char *relo_sec_name, *sec_name;
size_t sec_idx = shdr->sh_info, sym_idx;
struct bpf_program *prog;
struct reloc_desc *relos;
int err, i, nrels;
const char *sym_name;
__u32 insn_idx;
Elf_Scn *scn;
Elf_Data *scn_data;
Elf64_Sym *sym;
Elf64_Rel *rel;
if (sec_idx >= obj->efile.sec_cnt)
return -EINVAL;
scn = elf_sec_by_idx(obj, sec_idx);
scn_data = elf_sec_data(obj, scn);
if (!scn_data)
return -LIBBPF_ERRNO__FORMAT;
relo_sec_name = elf_sec_str(obj, shdr->sh_name);
sec_name = elf_sec_name(obj, scn);
if (!relo_sec_name || !sec_name)
return -EINVAL;
pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
relo_sec_name, sec_idx, sec_name);
nrels = shdr->sh_size / shdr->sh_entsize;
for (i = 0; i < nrels; i++) {
rel = elf_rel_by_idx(data, i);
if (!rel) {
pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
return -LIBBPF_ERRNO__FORMAT;
}
sym_idx = ELF64_R_SYM(rel->r_info);
sym = elf_sym_by_idx(obj, sym_idx);
if (!sym) {
pr_warn("sec '%s': symbol #%zu not found for relo #%d\n",
relo_sec_name, sym_idx, i);
return -LIBBPF_ERRNO__FORMAT;
}
if (sym->st_shndx >= obj->efile.sec_cnt) {
pr_warn("sec '%s': corrupted symbol #%zu pointing to invalid section #%zu for relo #%d\n",
relo_sec_name, sym_idx, (size_t)sym->st_shndx, i);
return -LIBBPF_ERRNO__FORMAT;
}
if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
relo_sec_name, (size_t)rel->r_offset, i);
return -LIBBPF_ERRNO__FORMAT;
}
insn_idx = rel->r_offset / BPF_INSN_SZ;
/* relocations against static functions are recorded as
* relocations against the section that contains a function;
* in such case, symbol will be STT_SECTION and sym.st_name
* will point to empty string (0), so fetch section name
* instead
*/
if (ELF64_ST_TYPE(sym->st_info) == STT_SECTION && sym->st_name == 0)
sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym->st_shndx));
else
sym_name = elf_sym_str(obj, sym->st_name);
sym_name = sym_name ?: "<?";
pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
relo_sec_name, i, insn_idx, sym_name);
prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
if (!prog) {
pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
relo_sec_name, i, sec_name, insn_idx);
continue;
}
relos = libbpf_reallocarray(prog->reloc_desc,
prog->nr_reloc + 1, sizeof(*relos));
if (!relos)
return -ENOMEM;
prog->reloc_desc = relos;
/* adjust insn_idx to local BPF program frame of reference */
insn_idx -= prog->sec_insn_off;
err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
insn_idx, sym_name, sym, rel);
if (err)
return err;
prog->nr_reloc++;
}
return 0;
}
static int map_fill_btf_type_info(struct bpf_object *obj, struct bpf_map *map)
{
int id;
if (!obj->btf)
return -ENOENT;
/* if it's BTF-defined map, we don't need to search for type IDs.
* For struct_ops map, it does not need btf_key_type_id and
* btf_value_type_id.
*/
if (map->sec_idx == obj->efile.btf_maps_shndx || bpf_map__is_struct_ops(map))
return 0;
/*
* LLVM annotates global data differently in BTF, that is,
* only as '.data', '.bss' or '.rodata'.
*/
if (!bpf_map__is_internal(map))
return -ENOENT;
id = btf__find_by_name(obj->btf, map->real_name);
if (id < 0)
return id;
map->btf_key_type_id = 0;
map->btf_value_type_id = id;
return 0;
}
static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
{
char file[PATH_MAX], buff[4096];
FILE *fp;
__u32 val;
int err;
snprintf(file, sizeof(file), "/proc/%d/fdinfo/%d", getpid(), fd);
memset(info, 0, sizeof(*info));
fp = fopen(file, "re");
if (!fp) {
err = -errno;
pr_warn("failed to open %s: %s. No procfs support?\n", file,
errstr(err));
return err;
}
while (fgets(buff, sizeof(buff), fp)) {
if (sscanf(buff, "map_type:\t%u", &val) == 1)
info->type = val;
else if (sscanf(buff, "key_size:\t%u", &val) == 1)
info->key_size = val;
else if (sscanf(buff, "value_size:\t%u", &val) == 1)
info->value_size = val;
else if (sscanf(buff, "max_entries:\t%u", &val) == 1)
info->max_entries = val;
else if (sscanf(buff, "map_flags:\t%i", &val) == 1)
info->map_flags = val;
}
fclose(fp);
return 0;
}
bool bpf_map__autocreate(const struct bpf_map *map)
{
return map->autocreate;
}
int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
{
if (map->obj->loaded)
return libbpf_err(-EBUSY);
map->autocreate = autocreate;
return 0;
}
int bpf_map__set_autoattach(struct bpf_map *map, bool autoattach)
{
if (!bpf_map__is_struct_ops(map))
return libbpf_err(-EINVAL);
map->autoattach = autoattach;
return 0;
}
bool bpf_map__autoattach(const struct bpf_map *map)
{
return map->autoattach;
}
int bpf_map__reuse_fd(struct bpf_map *map, int fd)
{
struct bpf_map_info info;
__u32 len = sizeof(info), name_len;
int new_fd, err;
char *new_name;
memset(&info, 0, len);
err = bpf_map_get_info_by_fd(fd, &info, &len);
if (err && errno == EINVAL)
err = bpf_get_map_info_from_fdinfo(fd, &info);
if (err)
return libbpf_err(err);
name_len = strlen(info.name);
if (name_len == BPF_OBJ_NAME_LEN - 1 && strncmp(map->name, info.name, name_len) == 0)
new_name = strdup(map->name);
else
new_name = strdup(info.name);
if (!new_name)
return libbpf_err(-errno);
/*
* Like dup(), but make sure new FD is >= 3 and has O_CLOEXEC set.
* This is similar to what we do in ensure_good_fd(), but without
* closing original FD.
*/
new_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
if (new_fd < 0) {
err = -errno;
goto err_free_new_name;
}
err = reuse_fd(map->fd, new_fd);
if (err)
goto err_free_new_name;
free(map->name);
map->name = new_name;
map->def.type = info.type;
map->def.key_size = info.key_size;
map->def.value_size = info.value_size;
map->def.max_entries = info.max_entries;
map->def.map_flags = info.map_flags;
map->btf_key_type_id = info.btf_key_type_id;
map->btf_value_type_id = info.btf_value_type_id;
map->reused = true;
map->map_extra = info.map_extra;
return 0;
err_free_new_name:
free(new_name);
return libbpf_err(err);
}
__u32 bpf_map__max_entries(const struct bpf_map *map)
{
return map->def.max_entries;
}
struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
{
if (!bpf_map_type__is_map_in_map(map->def.type))
return errno = EINVAL, NULL;
return map->inner_map;
}
int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
{
if (map->obj->loaded)
return libbpf_err(-EBUSY);
map->def.max_entries = max_entries;
/* auto-adjust BPF ringbuf map max_entries to be a multiple of page size */
if (map_is_ringbuf(map))
map->def.max_entries = adjust_ringbuf_sz(map->def.max_entries);
return 0;
}
static int bpf_object_prepare_token(struct bpf_object *obj)
{
const char *bpffs_path;
int bpffs_fd = -1, token_fd, err;
bool mandatory;
enum libbpf_print_level level;
/* token is explicitly prevented */
if (obj->token_path && obj->token_path[0] == '\0') {
pr_debug("object '%s': token is prevented, skipping...\n", obj->name);
return 0;
}
mandatory = obj->token_path != NULL;
level = mandatory ? LIBBPF_WARN : LIBBPF_DEBUG;
bpffs_path = obj->token_path ?: BPF_FS_DEFAULT_PATH;
bpffs_fd = open(bpffs_path, O_DIRECTORY, O_RDWR);
if (bpffs_fd < 0) {
err = -errno;
__pr(level, "object '%s': failed (%s) to open BPF FS mount at '%s'%s\n",
obj->name, errstr(err), bpffs_path,
mandatory ? "" : ", skipping optional step...");
return mandatory ? err : 0;
}
token_fd = bpf_token_create(bpffs_fd, 0);
close(bpffs_fd);
if (token_fd < 0) {
if (!mandatory && token_fd == -ENOENT) {
pr_debug("object '%s': BPF FS at '%s' doesn't have BPF token delegation set up, skipping...\n",
obj->name, bpffs_path);
return 0;
}
__pr(level, "object '%s': failed (%d) to create BPF token from '%s'%s\n",
obj->name, token_fd, bpffs_path,
mandatory ? "" : ", skipping optional step...");
return mandatory ? token_fd : 0;
}
obj->feat_cache = calloc(1, sizeof(*obj->feat_cache));
if (!obj->feat_cache) {
close(token_fd);
return -ENOMEM;
}
obj->token_fd = token_fd;
obj->feat_cache->token_fd = token_fd;
return 0;
}
static int
bpf_object__probe_loading(struct bpf_object *obj)
{
struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
int ret, insn_cnt = ARRAY_SIZE(insns);
LIBBPF_OPTS(bpf_prog_load_opts, opts,
.token_fd = obj->token_fd,
.prog_flags = obj->token_fd ? BPF_F_TOKEN_FD : 0,
);
if (obj->gen_loader)
return 0;
ret = bump_rlimit_memlock();
if (ret)
pr_warn("Failed to bump RLIMIT_MEMLOCK (err = %s), you might need to do it explicitly!\n",
errstr(ret));
/* make sure basic loading works */
ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL", insns, insn_cnt, &opts);
if (ret < 0)
ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts);
if (ret < 0) {
ret = errno;
pr_warn("Error in %s(): %s. Couldn't load trivial BPF program. Make sure your kernel supports BPF (CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is set to big enough value.\n",
__func__, errstr(ret));
return -ret;
}
close(ret);
return 0;
}
bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)
{
if (obj->gen_loader)
/* To generate loader program assume the latest kernel
* to avoid doing extra prog_load, map_create syscalls.
*/
return true;
if (obj->token_fd)
return feat_supported(obj->feat_cache, feat_id);
return feat_supported(NULL, feat_id);
}
static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
{
struct bpf_map_info map_info;
__u32 map_info_len = sizeof(map_info);
int err;
memset(&map_info, 0, map_info_len);
err = bpf_map_get_info_by_fd(map_fd, &map_info, &map_info_len);
if (err && errno == EINVAL)
err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
if (err) {
pr_warn("failed to get map info for map FD %d: %s\n", map_fd,
errstr(err));
return false;
}
return (map_info.type == map->def.type &&
map_info.key_size == map->def.key_size &&
map_info.value_size == map->def.value_size &&
map_info.max_entries == map->def.max_entries &&
map_info.map_flags == map->def.map_flags &&
map_info.map_extra == map->map_extra);
}
static int
bpf_object__reuse_map(struct bpf_map *map)
{
int err, pin_fd;
pin_fd = bpf_obj_get(map->pin_path);
if (pin_fd < 0) {
err = -errno;
if (err == -ENOENT) {
pr_debug("found no pinned map to reuse at '%s'\n",
map->pin_path);
return 0;
}
pr_warn("couldn't retrieve pinned map '%s': %s\n",
map->pin_path, errstr(err));
return err;
}
if (!map_is_reuse_compat(map, pin_fd)) {
pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
map->pin_path);
close(pin_fd);
return -EINVAL;
}
err = bpf_map__reuse_fd(map, pin_fd);
close(pin_fd);
if (err)
return err;
map->pinned = true;
pr_debug("reused pinned map at '%s'\n", map->pin_path);
return 0;
}
static int
bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
{
enum libbpf_map_type map_type = map->libbpf_type;
int err, zero = 0;
size_t mmap_sz;
if (obj->gen_loader) {
bpf_gen__map_update_elem(obj->gen_loader, map - obj->maps,
map->mmaped, map->def.value_size);
if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG)
bpf_gen__map_freeze(obj->gen_loader, map - obj->maps);
return 0;
}
err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
if (err) {
err = -errno;
pr_warn("map '%s': failed to set initial contents: %s\n",
bpf_map__name(map), errstr(err));
return err;
}
/* Freeze .rodata and .kconfig map as read-only from syscall side. */
if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
err = bpf_map_freeze(map->fd);
if (err) {
err = -errno;
pr_warn("map '%s': failed to freeze as read-only: %s\n",
bpf_map__name(map), errstr(err));
return err;
}
}
/* Remap anonymous mmap()-ed "map initialization image" as
* a BPF map-backed mmap()-ed memory, but preserving the same
* memory address. This will cause kernel to change process'
* page table to point to a different piece of kernel memory,
* but from userspace point of view memory address (and its
* contents, being identical at this point) will stay the
* same. This mapping will be released by bpf_object__close()
* as per normal clean up procedure.
*/
mmap_sz = bpf_map_mmap_sz(map);
if (map->def.map_flags & BPF_F_MMAPABLE) {
void *mmaped;
int prot;
if (map->def.map_flags & BPF_F_RDONLY_PROG)
prot = PROT_READ;
else
prot = PROT_READ | PROT_WRITE;
mmaped = mmap(map->mmaped, mmap_sz, prot, MAP_SHARED | MAP_FIXED, map->fd, 0);
if (mmaped == MAP_FAILED) {
err = -errno;
pr_warn("map '%s': failed to re-mmap() contents: %s\n",
bpf_map__name(map), errstr(err));
return err;
}
map->mmaped = mmaped;
} else if (map->mmaped) {
munmap(map->mmaped, mmap_sz);
map->mmaped = NULL;
}
return 0;
}
static void bpf_map__destroy(struct bpf_map *map);
static bool map_is_created(const struct bpf_map *map)
{
return map->obj->loaded || map->reused;
}
static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
{
LIBBPF_OPTS(bpf_map_create_opts, create_attr);
struct bpf_map_def *def = &map->def;
const char *map_name = NULL;
int err = 0, map_fd;
if (kernel_supports(obj, FEAT_PROG_NAME))
map_name = map->name;
create_attr.map_ifindex = map->map_ifindex;
create_attr.map_flags = def->map_flags;
create_attr.numa_node = map->numa_node;
create_attr.map_extra = map->map_extra;
create_attr.token_fd = obj->token_fd;
if (obj->token_fd)
create_attr.map_flags |= BPF_F_TOKEN_FD;
if (bpf_map__is_struct_ops(map)) {
create_attr.btf_vmlinux_value_type_id = map->btf_vmlinux_value_type_id;
if (map->mod_btf_fd >= 0) {
create_attr.value_type_btf_obj_fd = map->mod_btf_fd;
create_attr.map_flags |= BPF_F_VTYPE_BTF_OBJ_FD;
}
}
if (obj->btf && btf__fd(obj->btf) >= 0) {
create_attr.btf_fd = btf__fd(obj->btf);
create_attr.btf_key_type_id = map->btf_key_type_id;
create_attr.btf_value_type_id = map->btf_value_type_id;
}
if (bpf_map_type__is_map_in_map(def->type)) {
if (map->inner_map) {
err = map_set_def_max_entries(map->inner_map);
if (err)
return err;
err = bpf_object__create_map(obj, map->inner_map, true);
if (err) {
pr_warn("map '%s': failed to create inner map: %s\n",
map->name, errstr(err));
return err;
}
map->inner_map_fd = map->inner_map->fd;
}
if (map->inner_map_fd >= 0)
create_attr.inner_map_fd = map->inner_map_fd;
}
switch (def->type) {
case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
case BPF_MAP_TYPE_CGROUP_ARRAY:
case BPF_MAP_TYPE_STACK_TRACE:
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
case BPF_MAP_TYPE_DEVMAP:
case BPF_MAP_TYPE_DEVMAP_HASH:
case BPF_MAP_TYPE_CPUMAP:
case BPF_MAP_TYPE_XSKMAP:
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
case BPF_MAP_TYPE_QUEUE:
case BPF_MAP_TYPE_STACK:
case BPF_MAP_TYPE_ARENA:
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
map->btf_key_type_id = 0;
map->btf_value_type_id = 0;
break;
case BPF_MAP_TYPE_STRUCT_OPS:
create_attr.btf_value_type_id = 0;
break;
default:
break;
}
if (obj->gen_loader) {
bpf_gen__map_create(obj->gen_loader, def->type, map_name,
def->key_size, def->value_size, def->max_entries,
&create_attr, is_inner ? -1 : map - obj->maps);
/* We keep pretenting we have valid FD to pass various fd >= 0
* checks by just keeping original placeholder FDs in place.
* See bpf_object__add_map() comment.
* This placeholder fd will not be used with any syscall and
* will be reset to -1 eventually.
*/
map_fd = map->fd;
} else {
map_fd = bpf_map_create(def->type, map_name,
def->key_size, def->value_size,
def->max_entries, &create_attr);
}
if (map_fd < 0 && (create_attr.btf_key_type_id || create_attr.btf_value_type_id)) {
err = -errno;
pr_warn("Error in bpf_create_map_xattr(%s): %s. Retrying without BTF.\n",
map->name, errstr(err));
create_attr.btf_fd = 0;
create_attr.btf_key_type_id = 0;
create_attr.btf_value_type_id = 0;
map->btf_key_type_id = 0;
map->btf_value_type_id = 0;
map_fd = bpf_map_create(def->type, map_name,
def->key_size, def->value_size,
def->max_entries, &create_attr);
}
if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
if (obj->gen_loader)
map->inner_map->fd = -1;
bpf_map__destroy(map->inner_map);
zfree(&map->inner_map);
}
if (map_fd < 0)
return map_fd;
/* obj->gen_loader case, prevent reuse_fd() from closing map_fd */
if (map->fd == map_fd)
return 0;
/* Keep placeholder FD value but now point it to the BPF map object.
* This way everything that relied on this map's FD (e.g., relocated
* ldimm64 instructions) will stay valid and won't need adjustments.
* map->fd stays valid but now point to what map_fd points to.
*/
return reuse_fd(map->fd, map_fd);
}
static int init_map_in_map_slots(struct bpf_object *obj, struct bpf_map *map)
{
const struct bpf_map *targ_map;
unsigned int i;
int fd, err = 0;
for (i = 0; i < map->init_slots_sz; i++) {
if (!map->init_slots[i])
continue;
targ_map = map->init_slots[i];
fd = targ_map->fd;
if (obj->gen_loader) {
bpf_gen__populate_outer_map(obj->gen_loader,
map - obj->maps, i,
targ_map - obj->maps);
} else {
err = bpf_map_update_elem(map->fd, &i, &fd, 0);
}
if (err) {
err = -errno;
pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %s\n",
map->name, i, targ_map->name, fd, errstr(err));
return err;
}
pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
map->name, i, targ_map->name, fd);
}
zfree(&map->init_slots);
map->init_slots_sz = 0;
return 0;
}
static int init_prog_array_slots(struct bpf_object *obj, struct bpf_map *map)
{
const struct bpf_program *targ_prog;
unsigned int i;
int fd, err;
if (obj->gen_loader)
return -ENOTSUP;
for (i = 0; i < map->init_slots_sz; i++) {
if (!map->init_slots[i])
continue;
targ_prog = map->init_slots[i];
fd = bpf_program__fd(targ_prog);
err = bpf_map_update_elem(map->fd, &i, &fd, 0);
if (err) {
err = -errno;
pr_warn("map '%s': failed to initialize slot [%d] to prog '%s' fd=%d: %s\n",
map->name, i, targ_prog->name, fd, errstr(err));
return err;
}
pr_debug("map '%s': slot [%d] set to prog '%s' fd=%d\n",
map->name, i, targ_prog->name, fd);
}
zfree(&map->init_slots);
map->init_slots_sz = 0;
return 0;
}
static int bpf_object_init_prog_arrays(struct bpf_object *obj)
{
struct bpf_map *map;
int i, err;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
if (!map->init_slots_sz || map->def.type != BPF_MAP_TYPE_PROG_ARRAY)
continue;
err = init_prog_array_slots(obj, map);
if (err < 0)
return err;
}
return 0;
}
static int map_set_def_max_entries(struct bpf_map *map)
{
if (map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !map->def.max_entries) {
int nr_cpus;
nr_cpus = libbpf_num_possible_cpus();
if (nr_cpus < 0) {
pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
map->name, nr_cpus);
return nr_cpus;
}
pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
map->def.max_entries = nr_cpus;
}
return 0;
}
static int
bpf_object__create_maps(struct bpf_object *obj)
{
struct bpf_map *map;
unsigned int i, j;
int err;
bool retried;
for (i = 0; i < obj->nr_maps; i++) {
map = &obj->maps[i];
/* To support old kernels, we skip creating global data maps
* (.rodata, .data, .kconfig, etc); later on, during program
* loading, if we detect that at least one of the to-be-loaded
* programs is referencing any global data map, we'll error
* out with program name and relocation index logged.
* This approach allows to accommodate Clang emitting
* unnecessary .rodata.str1.1 sections for string literals,
* but also it allows to have CO-RE applications that use
* global variables in some of BPF programs, but not others.
* If those global variable-using programs are not loaded at
* runtime due to bpf_program__set_autoload(prog, false),
* bpf_object loading will succeed just fine even on old
* kernels.
*/
if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
map->autocreate = false;
if (!map->autocreate) {
pr_debug("map '%s': skipped auto-creating...\n", map->name);
continue;
}
err = map_set_def_max_entries(map);
if (err)
goto err_out;
retried = false;
retry:
if (map->pin_path) {
err = bpf_object__reuse_map(map);
if (err) {
pr_warn("map '%s': error reusing pinned map\n",
map->name);
goto err_out;
}
if (retried && map->fd < 0) {
pr_warn("map '%s': cannot find pinned map\n",
map->name);
err = -ENOENT;
goto err_out;
}
}
if (map->reused) {
pr_debug("map '%s': skipping creation (preset fd=%d)\n",
map->name, map->fd);
} else {
err = bpf_object__create_map(obj, map, false);
if (err)
goto err_out;
pr_debug("map '%s': created successfully, fd=%d\n",
map->name, map->fd);
if (bpf_map__is_internal(map)) {
err = bpf_object__populate_internal_map(obj, map);
if (err < 0)
goto err_out;
} else if (map->def.type == BPF_MAP_TYPE_ARENA) {
map->mmaped = mmap((void *)(long)map->map_extra,
bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
map->map_extra ? MAP_SHARED | MAP_FIXED : MAP_SHARED,
map->fd, 0);
if (map->mmaped == MAP_FAILED) {
err = -errno;
map->mmaped = NULL;
pr_warn("map '%s': failed to mmap arena: %s\n",
map->name, errstr(err));
return err;
}
if (obj->arena_data) {
memcpy(map->mmaped, obj->arena_data, obj->arena_data_sz);
zfree(&obj->arena_data);
}
}
if (map->init_slots_sz && map->def.type != BPF_MAP_TYPE_PROG_ARRAY) {
err = init_map_in_map_slots(obj, map);
if (err < 0)
goto err_out;
}
}
if (map->pin_path && !map->pinned) {
err = bpf_map__pin(map, NULL);
if (err) {
if (!retried && err == -EEXIST) {
retried = true;
goto retry;
}
pr_warn("map '%s': failed to auto-pin at '%s': %s\n",
map->name, map->pin_path, errstr(err));
goto err_out;
}
}
}
return 0;
err_out:
pr_warn("map '%s': failed to create: %s\n", map->name, errstr(err));
pr_perm_msg(err);
for (j = 0; j < i; j++)
zclose(obj->maps[j].fd);
return err;
}
static bool bpf_core_is_flavor_sep(const char *s)
{
/* check X___Y name pattern, where X and Y are not underscores */
return s[0] != '_' && /* X */
s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
s[4] != '_'; /* Y */
}
/* Given 'some_struct_name___with_flavor' return the length of a name prefix
* before last triple underscore. Struct name part after last triple
* underscore is ignored by BPF CO-RE relocation during relocation matching.
*/
size_t bpf_core_essential_name_len(const char *name)
{
size_t n = strlen(name);
int i;
for (i = n - 5; i >= 0; i--) {
if (bpf_core_is_flavor_sep(name + i))
return i + 1;
}
return n;
}
void bpf_core_free_cands(struct bpf_core_cand_list *cands)
{
if (!cands)
return;
free(cands->cands);
free(cands);
}
int bpf_core_add_cands(struct bpf_core_cand *local_cand,
size_t local_essent_len,
const struct btf *targ_btf,
const char *targ_btf_name,
int targ_start_id,
struct bpf_core_cand_list *cands)
{
struct bpf_core_cand *new_cands, *cand;
const struct btf_type *t, *local_t;
const char *targ_name, *local_name;
size_t targ_essent_len;
int n, i;
local_t = btf__type_by_id(local_cand->btf, local_cand->id);
local_name = btf__str_by_offset(local_cand->btf, local_t->name_off);
n = btf__type_cnt(targ_btf);
for (i = targ_start_id; i < n; i++) {
t = btf__type_by_id(targ_btf, i);
if (!btf_kind_core_compat(t, local_t))
continue;
targ_name = btf__name_by_offset(targ_btf, t->name_off);
if (str_is_empty(targ_name))
continue;
targ_essent_len = bpf_core_essential_name_len(targ_name);
if (targ_essent_len != local_essent_len)
continue;
if (strncmp(local_name, targ_name, local_essent_len) != 0)
continue;
pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
local_cand->id, btf_kind_str(local_t),
local_name, i, btf_kind_str(t), targ_name,
targ_btf_name);
new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
sizeof(*cands->cands));
if (!new_cands)
return -ENOMEM;
cand = &new_cands[cands->len];
cand->btf = targ_btf;
cand->id = i;
cands->cands = new_cands;
cands->len++;
}
return 0;
}
static int load_module_btfs(struct bpf_object *obj)
{
struct bpf_btf_info info;
struct module_btf *mod_btf;
struct btf *btf;
char name[64];
__u32 id = 0, len;
int err, fd;
if (obj->btf_modules_loaded)
return 0;
if (obj->gen_loader)
return 0;
/* don't do this again, even if we find no module BTFs */
obj->btf_modules_loaded = true;
/* kernel too old to support module BTFs */
if (!kernel_supports(obj, FEAT_MODULE_BTF))
return 0;
while (true) {
err = bpf_btf_get_next_id(id, &id);
if (err && errno == ENOENT)
return 0;
if (err && errno == EPERM) {
pr_debug("skipping module BTFs loading, missing privileges\n");
return 0;
}
if (err) {
err = -errno;
pr_warn("failed to iterate BTF objects: %s\n", errstr(err));
return err;
}
fd = bpf_btf_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue; /* expected race: BTF was unloaded */
err = -errno;
pr_warn("failed to get BTF object #%d FD: %s\n", id, errstr(err));
return err;
}
len = sizeof(info);
memset(&info, 0, sizeof(info));
info.name = ptr_to_u64(name);
info.name_len = sizeof(name);
err = bpf_btf_get_info_by_fd(fd, &info, &len);
if (err) {
err = -errno;
pr_warn("failed to get BTF object #%d info: %s\n", id, errstr(err));
goto err_out;
}
/* ignore non-module BTFs */
if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
close(fd);
continue;
}
btf = btf_get_from_fd(fd, obj->btf_vmlinux);
err = libbpf_get_error(btf);
if (err) {
pr_warn("failed to load module [%s]'s BTF object #%d: %s\n",
name, id, errstr(err));
goto err_out;
}
err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
if (err)
goto err_out;
mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
mod_btf->btf = btf;
mod_btf->id = id;
mod_btf->fd = fd;
mod_btf->name = strdup(name);
if (!mod_btf->name) {
err = -ENOMEM;
goto err_out;
}
continue;
err_out:
close(fd);
return err;
}
return 0;
}
static struct bpf_core_cand_list *
bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
{
struct bpf_core_cand local_cand = {};
struct bpf_core_cand_list *cands;
const struct btf *main_btf;
const struct btf_type *local_t;
const char *local_name;
size_t local_essent_len;
int err, i;
local_cand.btf = local_btf;
local_cand.id = local_type_id;
local_t = btf__type_by_id(local_btf, local_type_id);
if (!local_t)
return ERR_PTR(-EINVAL);
local_name = btf__name_by_offset(local_btf, local_t->name_off);
if (str_is_empty(local_name))
return ERR_PTR(-EINVAL);
local_essent_len = bpf_core_essential_name_len(local_name);
cands = calloc(1, sizeof(*cands));
if (!cands)
return ERR_PTR(-ENOMEM);
/* Attempt to find target candidates in vmlinux BTF first */
main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
if (err)
goto err_out;
/* if vmlinux BTF has any candidate, don't got for module BTFs */
if (cands->len)
return cands;
/* if vmlinux BTF was overridden, don't attempt to load module BTFs */
if (obj->btf_vmlinux_override)
return cands;
/* now look through module BTFs, trying to still find candidates */
err = load_module_btfs(obj);
if (err)
goto err_out;
for (i = 0; i < obj->btf_module_cnt; i++) {
err = bpf_core_add_cands(&local_cand, local_essent_len,
obj->btf_modules[i].btf,
obj->btf_modules[i].name,
btf__type_cnt(obj->btf_vmlinux),
cands);
if (err)
goto err_out;
}
return cands;
err_out:
bpf_core_free_cands(cands);
return ERR_PTR(err);
}
/* Check local and target types for compatibility. This check is used for
* type-based CO-RE relocations and follow slightly different rules than
* field-based relocations. This function assumes that root types were already
* checked for name match. Beyond that initial root-level name check, names
* are completely ignored. Compatibility rules are as follows:
* - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
* kind should match for local and target types (i.e., STRUCT is not
* compatible with UNION);
* - for ENUMs, the size is ignored;
* - for INT, size and signedness are ignored;
* - for ARRAY, dimensionality is ignored, element types are checked for
* compatibility recursively;
* - CONST/VOLATILE/RESTRICT modifiers are ignored;
* - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
* - FUNC_PROTOs are compatible if they have compatible signature: same
* number of input args and compatible return and argument types.
* These rules are not set in stone and probably will be adjusted as we get
* more experience with using BPF CO-RE relocations.
*/
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
}
int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
}
static size_t bpf_core_hash_fn(const long key, void *ctx)
{
return key;
}
static bool bpf_core_equal_fn(const long k1, const long k2, void *ctx)
{
return k1 == k2;
}
static int record_relo_core(struct bpf_program *prog,
const struct bpf_core_relo *core_relo, int insn_idx)
{
struct reloc_desc *relos, *relo;
relos = libbpf_reallocarray(prog->reloc_desc,
prog->nr_reloc + 1, sizeof(*relos));
if (!relos)
return -ENOMEM;
relo = &relos[prog->nr_reloc];
relo->type = RELO_CORE;
relo->insn_idx = insn_idx;
relo->core_relo = core_relo;
prog->reloc_desc = relos;
prog->nr_reloc++;
return 0;
}
static const struct bpf_core_relo *find_relo_core(struct bpf_program *prog, int insn_idx)
{
struct reloc_desc *relo;
int i;
for (i = 0; i < prog->nr_reloc; i++) {
relo = &prog->reloc_desc[i];
if (relo->type != RELO_CORE || relo->insn_idx != insn_idx)
continue;
return relo->core_relo;
}
return NULL;
}
static int bpf_core_resolve_relo(struct bpf_program *prog,
const struct bpf_core_relo *relo,
int relo_idx,
const struct btf *local_btf,
struct hashmap *cand_cache,
struct bpf_core_relo_res *targ_res)
{
struct bpf_core_spec specs_scratch[3] = {};
struct bpf_core_cand_list *cands = NULL;
const char *prog_name = prog->name;
const struct btf_type *local_type;
const char *local_name;
__u32 local_id = relo->type_id;
int err;
local_type = btf__type_by_id(local_btf, local_id);
if (!local_type)
return -EINVAL;
local_name = btf__name_by_offset(local_btf, local_type->name_off);
if (!local_name)
return -EINVAL;
if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
!hashmap__find(cand_cache, local_id, &cands)) {
cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
if (IS_ERR(cands)) {
pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
prog_name, relo_idx, local_id, btf_kind_str(local_type),
local_name, PTR_ERR(cands));
return PTR_ERR(cands);
}
err = hashmap__set(cand_cache, local_id, cands, NULL, NULL);
if (err) {
bpf_core_free_cands(cands);
return err;
}
}
return bpf_core_calc_relo_insn(prog_name, relo, relo_idx, local_btf, cands, specs_scratch,
targ_res);
}
static int
bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
{
const struct btf_ext_info_sec *sec;
struct bpf_core_relo_res targ_res;
const struct bpf_core_relo *rec;
const struct btf_ext_info *seg;
struct hashmap_entry *entry;
struct hashmap *cand_cache = NULL;
struct bpf_program *prog;
struct bpf_insn *insn;
const char *sec_name;
int i, err = 0, insn_idx, sec_idx, sec_num;
if (obj->btf_ext->core_relo_info.len == 0)
return 0;
if (targ_btf_path) {
obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
err = libbpf_get_error(obj->btf_vmlinux_override);
if (err) {
pr_warn("failed to parse target BTF: %s\n", errstr(err));
return err;
}
}
cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
if (IS_ERR(cand_cache)) {
err = PTR_ERR(cand_cache);
goto out;
}
seg = &obj->btf_ext->core_relo_info;
sec_num = 0;
for_each_btf_ext_sec(seg, sec) {
sec_idx = seg->sec_idxs[sec_num];
sec_num++;
sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
if (str_is_empty(sec_name)) {
err = -EINVAL;
goto out;
}
pr_debug("sec '%s': found %d CO-RE relocations\n", sec_name, sec->num_info);
for_each_btf_ext_rec(seg, sec, i, rec) {
if (rec->insn_off % BPF_INSN_SZ)
return -EINVAL;
insn_idx = rec->insn_off / BPF_INSN_SZ;
prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
if (!prog) {
/* When __weak subprog is "overridden" by another instance
* of the subprog from a different object file, linker still
* appends all the .BTF.ext info that used to belong to that
* eliminated subprogram.
* This is similar to what x86-64 linker does for relocations.
* So just ignore such relocations just like we ignore
* subprog instructions when discovering subprograms.
*/
pr_debug("sec '%s': skipping CO-RE relocation #%d for insn #%d belonging to eliminated weak subprogram\n",
sec_name, i, insn_idx);
continue;
}
/* no need to apply CO-RE relocation if the program is
* not going to be loaded
*/
if (!prog->autoload)
continue;
/* adjust insn_idx from section frame of reference to the local
* program's frame of reference; (sub-)program code is not yet
* relocated, so it's enough to just subtract in-section offset
*/
insn_idx = insn_idx - prog->sec_insn_off;
if (insn_idx >= prog->insns_cnt)
return -EINVAL;
insn = &prog->insns[insn_idx];
err = record_relo_core(prog, rec, insn_idx);
if (err) {
pr_warn("prog '%s': relo #%d: failed to record relocation: %s\n",
prog->name, i, errstr(err));
goto out;
}
if (prog->obj->gen_loader)
continue;
err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res);
if (err) {
pr_warn("prog '%s': relo #%d: failed to relocate: %s\n",
prog->name, i, errstr(err));
goto out;
}
err = bpf_core_patch_insn(prog->name, insn, insn_idx, rec, i, &targ_res);
if (err) {
pr_warn("prog '%s': relo #%d: failed to patch insn #%u: %s\n",
prog->name, i, insn_idx, errstr(err));
goto out;
}
}
}
out:
/* obj->btf_vmlinux and module BTFs are freed after object load */
btf__free(obj->btf_vmlinux_override);
obj->btf_vmlinux_override = NULL;
if (!IS_ERR_OR_NULL(cand_cache)) {
hashmap__for_each_entry(cand_cache, entry, i) {
bpf_core_free_cands(entry->pvalue);
}
hashmap__free(cand_cache);
}
return err;
}
/* base map load ldimm64 special constant, used also for log fixup logic */
#define POISON_LDIMM64_MAP_BASE 2001000000
#define POISON_LDIMM64_MAP_PFX "200100"
static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
int insn_idx, struct bpf_insn *insn,
int map_idx, const struct bpf_map *map)
{
int i;
pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
prog->name, relo_idx, insn_idx, map_idx, map->name);
/* we turn single ldimm64 into two identical invalid calls */
for (i = 0; i < 2; i++) {
insn->code = BPF_JMP | BPF_CALL;
insn->dst_reg = 0;
insn->src_reg = 0;
insn->off = 0;
/* if this instruction is reachable (not a dead code),
* verifier will complain with something like:
* invalid func unknown#2001000123
* where lower 123 is map index into obj->maps[] array
*/
insn->imm = POISON_LDIMM64_MAP_BASE + map_idx;
insn++;
}
}
/* unresolved kfunc call special constant, used also for log fixup logic */
#define POISON_CALL_KFUNC_BASE 2002000000
#define POISON_CALL_KFUNC_PFX "2002"
static void poison_kfunc_call(struct bpf_program *prog, int relo_idx,
int insn_idx, struct bpf_insn *insn,
int ext_idx, const struct extern_desc *ext)
{
pr_debug("prog '%s': relo #%d: poisoning insn #%d that calls kfunc '%s'\n",
prog->name, relo_idx, insn_idx, ext->name);
/* we turn kfunc call into invalid helper call with identifiable constant */
insn->code = BPF_JMP | BPF_CALL;
insn->dst_reg = 0;
insn->src_reg = 0;
insn->off = 0;
/* if this instruction is reachable (not a dead code),
* verifier will complain with something like:
* invalid func unknown#2001000123
* where lower 123 is extern index into obj->externs[] array
*/
insn->imm = POISON_CALL_KFUNC_BASE + ext_idx;
}
/* Relocate data references within program code:
* - map references;
* - global variable references;
* - extern references.
*/
static int
bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
{
int i;
for (i = 0; i < prog->nr_reloc; i++) {
struct reloc_desc *relo = &prog->reloc_desc[i];
struct bpf_insn *insn = &prog->insns[relo->insn_idx];
const struct bpf_map *map;
struct extern_desc *ext;
switch (relo->type) {
case RELO_LD64:
map = &obj->maps[relo->map_idx];
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
insn[0].imm = relo->map_idx;
} else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_FD;
insn[0].imm = map->fd;
} else {
poison_map_ldimm64(prog, i, relo->insn_idx, insn,
relo->map_idx, map);
}
break;
case RELO_DATA:
map = &obj->maps[relo->map_idx];
insn[1].imm = insn[0].imm + relo->sym_off;
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
insn[0].imm = relo->map_idx;
} else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
