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* (C) 2015 Red Hat GmbH
* Author: Florian Westphal <fw@strlen.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/static_key.h>
#include <linux/hash.h>
#include <linux/jhash.h>
#include <linux/if_vlan.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#define NFT_TRACETYPE_LL_HSIZE 20
#define NFT_TRACETYPE_NETWORK_HSIZE 40
#define NFT_TRACETYPE_TRANSPORT_HSIZE 20
DEFINE_STATIC_KEY_FALSE(nft_trace_enabled);
EXPORT_SYMBOL_GPL(nft_trace_enabled);
static int trace_fill_id(struct sk_buff *nlskb, struct sk_buff *skb)
{
__be32 id;
/* using skb address as ID results in a limited number of
* values (and quick reuse).
*
* So we attempt to use as many skb members that will not
* change while skb is with netfilter.
*/
id = (__be32)jhash_2words(hash32_ptr(skb), skb_get_hash(skb),
skb->skb_iif);
return nla_put_be32(nlskb, NFTA_TRACE_ID, id);
}
static int trace_fill_header(struct sk_buff *nlskb, u16 type,
const struct sk_buff *skb,
int off, unsigned int len)
{
struct nlattr *nla;
if (len == 0)
return 0;
nla = nla_reserve(nlskb, type, len);
if (!nla || skb_copy_bits(skb, off, nla_data(nla), len))
return -1;
return 0;
}
static int nf_trace_fill_ll_header(struct sk_buff *nlskb,
const struct sk_buff *skb)
{
struct vlan_ethhdr veth;
int off;
BUILD_BUG_ON(sizeof(veth) > NFT_TRACETYPE_LL_HSIZE);
off = skb_mac_header(skb) - skb->data;
if (off != -ETH_HLEN)
return -1;
if (skb_copy_bits(skb, off, &veth, ETH_HLEN))
return -1;
veth.h_vlan_proto = skb->vlan_proto;
veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
veth.h_vlan_encapsulated_proto = skb->protocol;
return nla_put(nlskb, NFTA_TRACE_LL_HEADER, sizeof(veth), &veth);
}
static int nf_trace_fill_dev_info(struct sk_buff *nlskb,
const struct net_device *indev,
const struct net_device *outdev)
{
if (indev) {
if (nla_put_be32(nlskb, NFTA_TRACE_IIF,
htonl(indev->ifindex)))
return -1;
if (nla_put_be16(nlskb, NFTA_TRACE_IIFTYPE,
htons(indev->type)))
return -1;
}
if (outdev) {
if (nla_put_be32(nlskb, NFTA_TRACE_OIF,
htonl(outdev->ifindex)))
return -1;
if (nla_put_be16(nlskb, NFTA_TRACE_OIFTYPE,
htons(outdev->type)))
return -1;
}
return 0;
}
static int nf_trace_fill_pkt_info(struct sk_buff *nlskb,
const struct nft_pktinfo *pkt)
{
const struct sk_buff *skb = pkt->skb;
int off = skb_network_offset(skb);
unsigned int len, nh_end;
nh_end = pkt->tprot_set ? pkt->xt.thoff : skb->len;
len = min_t(unsigned int, nh_end - skb_network_offset(skb),
NFT_TRACETYPE_NETWORK_HSIZE);
if (trace_fill_header(nlskb, NFTA_TRACE_NETWORK_HEADER, skb, off, len))
return -1;
if (pkt->tprot_set) {
len = min_t(unsigned int, skb->len - pkt->xt.thoff,
NFT_TRACETYPE_TRANSPORT_HSIZE);
if (trace_fill_header(nlskb, NFTA_TRACE_TRANSPORT_HEADER, skb,
pkt->xt.thoff, len))
return -1;
}
if (!skb_mac_header_was_set(skb))
return 0;
if (skb_vlan_tag_get(skb))
return nf_trace_fill_ll_header(nlskb, skb);
off = skb_mac_header(skb) - skb->data;
len = min_t(unsigned int, -off, NFT_TRACETYPE_LL_HSIZE);
return trace_fill_header(nlskb, NFTA_TRACE_LL_HEADER,
skb, off, len);
}
static int nf_trace_fill_rule_info(struct sk_buff *nlskb,
const struct nft_traceinfo *info)
{
if (!info->rule)
return 0;
/* a continue verdict with ->type == RETURN means that this is
* an implicit return (end of chain reached).
*
* Since no rule matched, the ->rule pointer is invalid.
*/
if (info->type == NFT_TRACETYPE_RETURN &&
info->verdict->code == NFT_CONTINUE)
return 0;
return nla_put_be64(nlskb, NFTA_TRACE_RULE_HANDLE,
cpu_to_be64(info->rule->handle),
NFTA_TRACE_PAD);
}
void nft_trace_notify(struct nft_traceinfo *info)
{
const struct nft_pktinfo *pkt = info->pkt;
struct nfgenmsg *nfmsg;
struct nlmsghdr *nlh;
struct sk_buff *skb;
unsigned int size;
int event = (NFNL_SUBSYS_NFTABLES << 8) | NFT_MSG_TRACE;
if (!nfnetlink_has_listeners(pkt->net, NFNLGRP_NFTRACE))
return;
size = nlmsg_total_size(sizeof(struct nfgenmsg)) +
nla_total_size(NFT_TABLE_MAXNAMELEN) +
nla_total_size(NFT_CHAIN_MAXNAMELEN) +
nla_total_size_64bit(sizeof(__be64)) + /* rule handle */
nla_total_size(sizeof(__be32)) + /* trace type */
nla_total_size(0) + /* VERDICT, nested */
nla_total_size(sizeof(u32)) + /* verdict code */
nla_total_size(NFT_CHAIN_MAXNAMELEN) + /* jump target */
nla_total_size(sizeof(u32)) + /* id */
nla_total_size(NFT_TRACETYPE_LL_HSIZE) +
nla_total_size(NFT_TRACETYPE_NETWORK_HSIZE) +
nla_total_size(NFT_TRACETYPE_TRANSPORT_HSIZE) +
nla_total_size(sizeof(u32)) + /* iif */
nla_total_size(sizeof(__be16)) + /* iiftype */
nla_total_size(sizeof(u32)) + /* oif */
nla_total_size(sizeof(__be16)) + /* oiftype */
nla_total_size(sizeof(u32)) + /* mark */
nla_total_size(sizeof(u32)) + /* nfproto */
nla_total_size(sizeof(u32)); /* policy */
skb = nlmsg_new(size, GFP_ATOMIC);
if (!skb)
return;
nlh = nlmsg_put(skb, 0, 0, event, sizeof(struct nfgenmsg), 0);
if (!nlh)
goto nla_put_failure;
nfmsg = nlmsg_data(nlh);
nfmsg->nfgen_family = info->basechain->type->family;
nfmsg->version = NFNETLINK_V0;
nfmsg->res_id = 0;
if (nla_put_be32(skb, NFTA_TRACE_NFPROTO, htonl(pkt->pf)))
goto nla_put_failure;
if (nla_put_be32(skb, NFTA_TRACE_TYPE, htonl(info->type)))
goto nla_put_failure;
if (trace_fill_id(skb, pkt->skb))
goto nla_put_failure;
if (info->chain) {
if (nla_put_string(skb, NFTA_TRACE_CHAIN,
info->chain->name))
goto nla_put_failure;
if (nla_put_string(skb, NFTA_TRACE_TABLE,
info->chain->table->name))
goto nla_put_failure;
}
if (nf_trace_fill_rule_info(skb, info))
goto nla_put_failure;
switch (info->type) {
case NFT_TRACETYPE_UNSPEC:
case __NFT_TRACETYPE_MAX:
break;
case NFT_TRACETYPE_RETURN:
case NFT_TRACETYPE_RULE:
if (nft_verdict_dump(skb, NFTA_TRACE_VERDICT, info->verdict))
goto nla_put_failure;
break;
case NFT_TRACETYPE_POLICY:
if (nla_put_be32(skb, NFTA_TRACE_POLICY,
htonl(info->basechain->policy)))
goto nla_put_failure;
break;
}
if (pkt->skb->mark &&
nla_put_be32(skb, NFTA_TRACE_MARK, htonl(pkt->skb->mark)))
goto nla_put_failure;
if (!info->packet_dumped) {
if (nf_trace_fill_dev_info(skb, pkt->in, pkt->out))
goto nla_put_failure;
if (nf_trace_fill_pkt_info(skb, pkt))
goto nla_put_failure;
info->packet_dumped = true;
}
nlmsg_end(skb, nlh);
nfnetlink_send(skb, pkt->net, 0, NFNLGRP_NFTRACE, 0, GFP_ATOMIC);
return;
nla_put_failure:
WARN_ON_ONCE(1);
kfree_skb(skb);
}
void nft_trace_init(struct nft_traceinfo *info, const struct nft_pktinfo *pkt,
const struct nft_verdict *verdict,
const struct nft_chain *chain)
{
info->basechain = nft_base_chain(chain);
info->trace = true;
info->packet_dumped = false;
info->pkt = pkt;
info->verdict = verdict;
}
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