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* netfilter module for userspace bridged Ethernet frames logging daemons
*
* Authors:
* Bart De Schuymer <bdschuym@pandora.be>
* Harald Welte <laforge@netfilter.org>
*
* November, 2004
*
* Based on ipt_ULOG.c, which is
* (C) 2000-2002 by Harald Welte <laforge@netfilter.org>
*
* This module accepts two parameters:
*
* nlbufsiz:
* The parameter specifies how big the buffer for each netlink multicast
* group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
* get accumulated in the kernel until they are sent to userspace. It is
* NOT possible to allocate more than 128kB, and it is strongly discouraged,
* because atomically allocating 128kB inside the network rx softirq is not
* reliable. Please also keep in mind that this buffer size is allocated for
* each nlgroup you are using, so the total kernel memory usage increases
* by that factor.
*
* flushtimeout:
* Specify, after how many hundredths of a second the queue should be
* flushed even if it is not full yet.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <net/netlink.h>
#include <linux/netdevice.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_ulog.h>
#include <net/netfilter/nf_log.h>
#include <net/netns/generic.h>
#include <net/sock.h>
#include "../br_private.h"
static unsigned int nlbufsiz = NLMSG_GOODSIZE;
module_param(nlbufsiz, uint, 0600);
MODULE_PARM_DESC(nlbufsiz, "netlink buffer size (number of bytes) "
"(defaults to 4096)");
static unsigned int flushtimeout = 10;
module_param(flushtimeout, uint, 0600);
MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths ofa second) "
"(defaults to 10)");
typedef struct {
unsigned int qlen; /* number of nlmsgs' in the skb */
struct nlmsghdr *lastnlh; /* netlink header of last msg in skb */
struct sk_buff *skb; /* the pre-allocated skb */
struct timer_list timer; /* the timer function */
spinlock_t lock; /* the per-queue lock */
} ebt_ulog_buff_t;
static int ebt_ulog_net_id __read_mostly;
struct ebt_ulog_net {
unsigned int nlgroup[EBT_ULOG_MAXNLGROUPS];
ebt_ulog_buff_t ulog_buffers[EBT_ULOG_MAXNLGROUPS];
struct sock *ebtulognl;
};
static struct ebt_ulog_net *ebt_ulog_pernet(struct net *net)
{
return net_generic(net, ebt_ulog_net_id);
}
/* send one ulog_buff_t to userspace */
static void ulog_send(struct ebt_ulog_net *ebt, unsigned int nlgroup)
{
ebt_ulog_buff_t *ub = &ebt->ulog_buffers[nlgroup];
del_timer(&ub->timer);
if (!ub->skb)
return;
/* last nlmsg needs NLMSG_DONE */
if (ub->qlen > 1)
ub->lastnlh->nlmsg_type = NLMSG_DONE;
NETLINK_CB(ub->skb).dst_group = nlgroup + 1;
netlink_broadcast(ebt->ebtulognl, ub->skb, 0, nlgroup + 1, GFP_ATOMIC);
ub->qlen = 0;
ub->skb = NULL;
}
/* timer function to flush queue in flushtimeout time */
static void ulog_timer(unsigned long data)
{
struct ebt_ulog_net *ebt = container_of((void *)data,
struct ebt_ulog_net,
nlgroup[*(unsigned int *)data]);
ebt_ulog_buff_t *ub = &ebt->ulog_buffers[*(unsigned int *)data];
spin_lock_bh(&ub->lock);
if (ub->skb)
ulog_send(ebt, *(unsigned int *)data);
spin_unlock_bh(&ub->lock);
}
static struct sk_buff *ulog_alloc_skb(unsigned int size)
{
struct sk_buff *skb;
unsigned int n;
n = max(size, nlbufsiz);
skb = alloc_skb(n, GFP_ATOMIC | __GFP_NOWARN);
if (!skb) {
if (n > size) {
/* try to allocate only as much as we need for
* current packet */
skb = alloc_skb(size, GFP_ATOMIC);
if (!skb)
pr_debug("cannot even allocate buffer of size %ub\n",
size);
}
}
return skb;
}
static void ebt_ulog_packet(unsigned int hooknr, const struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
const struct ebt_ulog_info *uloginfo, const char *prefix)
{
ebt_ulog_packet_msg_t *pm;
size_t size, copy_len;
struct nlmsghdr *nlh;
struct net *net = dev_net(in ? in : out);
struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
unsigned int group = uloginfo->nlgroup;
ebt_ulog_buff_t *ub = &ebt->ulog_buffers[group];
spinlock_t *lock = &ub->lock;
ktime_t kt;
if ((uloginfo->cprange == 0) ||
(uloginfo->cprange > skb->len + ETH_HLEN))
copy_len = skb->len + ETH_HLEN;
else
copy_len = uloginfo->cprange;
size = nlmsg_total_size(sizeof(*pm) + copy_len);
if (size > nlbufsiz) {
pr_debug("Size %Zd needed, but nlbufsiz=%d\n", size, nlbufsiz);
return;
}
spin_lock_bh(lock);
if (!ub->skb) {
if (!(ub->skb = ulog_alloc_skb(size)))
goto unlock;
} else if (size > skb_tailroom(ub->skb)) {
ulog_send(ebt, group);
if (!(ub->skb = ulog_alloc_skb(size)))
goto unlock;
}
nlh = nlmsg_put(ub->skb, 0, ub->qlen, 0,
size - NLMSG_ALIGN(sizeof(*nlh)), 0);
if (!nlh) {
kfree_skb(ub->skb);
ub->skb = NULL;
goto unlock;
}
ub->qlen++;
pm = nlmsg_data(nlh);
/* Fill in the ulog data */
pm->version = EBT_ULOG_VERSION;
kt = ktime_get_real();
pm->stamp = ktime_to_timeval(kt);
if (ub->qlen == 1)
ub->skb->tstamp = kt;
pm->data_len = copy_len;
pm->mark = skb->mark;
pm->hook = hooknr;
if (uloginfo->prefix != NULL)
strcpy(pm->prefix, uloginfo->prefix);
else
*(pm->prefix) = '\0';
if (in) {
strcpy(pm->physindev, in->name);
/* If in isn't a bridge, then physindev==indev */
if (br_port_exists(in))
/* rcu_read_lock()ed by nf_hook_slow */
strcpy(pm->indev, br_port_get_rcu(in)->br->dev->name);
else
strcpy(pm->indev, in->name);
} else
pm->indev[0] = pm->physindev[0] = '\0';
if (out) {
/* If out exists, then out is a bridge port */
strcpy(pm->physoutdev, out->name);
/* rcu_read_lock()ed by nf_hook_slow */
strcpy(pm->outdev, br_port_get_rcu(out)->br->dev->name);
} else
pm->outdev[0] = pm->physoutdev[0] = '\0';
if (skb_copy_bits(skb, -ETH_HLEN, pm->data, copy_len) < 0)
BUG();
if (ub->qlen > 1)
ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
ub->lastnlh = nlh;
if (ub->qlen >= uloginfo->qthreshold)
ulog_send(ebt, group);
else if (!timer_pending(&ub->timer)) {
ub->timer.expires = jiffies + flushtimeout * HZ / 100;
add_timer(&ub->timer);
}
unlock:
spin_unlock_bh(lock);
}
/* this function is registered with the netfilter core */
static void ebt_log_packet(u_int8_t pf, unsigned int hooknum,
const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct nf_loginfo *li,
const char *prefix)
{
struct ebt_ulog_info loginfo;
if (!li || li->type != NF_LOG_TYPE_ULOG) {
loginfo.nlgroup = EBT_ULOG_DEFAULT_NLGROUP;
loginfo.cprange = 0;
loginfo.qthreshold = EBT_ULOG_DEFAULT_QTHRESHOLD;
loginfo.prefix[0] = '\0';
} else {
loginfo.nlgroup = li->u.ulog.group;
loginfo.cprange = li->u.ulog.copy_len;
loginfo.qthreshold = li->u.ulog.qthreshold;
strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
}
ebt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
}
static unsigned int
ebt_ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
ebt_ulog_packet(par->hooknum, skb, par->in, par->out,
par->targinfo, NULL);
return EBT_CONTINUE;
}
static int ebt_ulog_tg_check(const struct xt_tgchk_param *par)
{
struct ebt_ulog_info *uloginfo = par->targinfo;
if (uloginfo->nlgroup > 31)
return -EINVAL;
uloginfo->prefix[EBT_ULOG_PREFIX_LEN - 1] = '\0';
if (uloginfo->qthreshold > EBT_ULOG_MAX_QLEN)
uloginfo->qthreshold = EBT_ULOG_MAX_QLEN;
return 0;
}
static struct xt_target ebt_ulog_tg_reg __read_mostly = {
.name = "ulog",
.revision = 0,
.family = NFPROTO_BRIDGE,
.target = ebt_ulog_tg,
.checkentry = ebt_ulog_tg_check,
.targetsize = sizeof(struct ebt_ulog_info),
.me = THIS_MODULE,
};
static struct nf_logger ebt_ulog_logger __read_mostly = {
.name = "ebt_ulog",
.logfn = &ebt_log_packet,
.me = THIS_MODULE,
};
static int __net_init ebt_ulog_net_init(struct net *net)
{
int i;
struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
struct netlink_kernel_cfg cfg = {
.groups = EBT_ULOG_MAXNLGROUPS,
};
/* initialize ulog_buffers */
for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
ebt->nlgroup[i] = i;
setup_timer(&ebt->ulog_buffers[i].timer, ulog_timer,
(unsigned long)&ebt->nlgroup[i]);
spin_lock_init(&ebt->ulog_buffers[i].lock);
}
ebt->ebtulognl = netlink_kernel_create(net, NETLINK_NFLOG, &cfg);
if (!ebt->ebtulognl)
return -ENOMEM;
nf_log_set(net, NFPROTO_BRIDGE, &ebt_ulog_logger);
return 0;
}
static void __net_exit ebt_ulog_net_fini(struct net *net)
{
int i;
struct ebt_ulog_net *ebt = ebt_ulog_pernet(net);
nf_log_unset(net, &ebt_ulog_logger);
for (i = 0; i < EBT_ULOG_MAXNLGROUPS; i++) {
ebt_ulog_buff_t *ub = &ebt->ulog_buffers[i];
del_timer(&ub->timer);
if (ub->skb) {
kfree_skb(ub->skb);
ub->skb = NULL;
}
}
netlink_kernel_release(ebt->ebtulognl);
}
static struct pernet_operations ebt_ulog_net_ops = {
.init = ebt_ulog_net_init,
.exit = ebt_ulog_net_fini,
.id = &ebt_ulog_net_id,
.size = sizeof(struct ebt_ulog_net),
};
static int __init ebt_ulog_init(void)
{
int ret;
if (nlbufsiz >= 128*1024) {
pr_warn("Netlink buffer has to be <= 128kB,"
"please try a smaller nlbufsiz parameter.\n");
return -EINVAL;
}
ret = register_pernet_subsys(&ebt_ulog_net_ops);
if (ret)
goto out_pernet;
ret = xt_register_target(&ebt_ulog_tg_reg);
if (ret)
goto out_target;
nf_log_register(NFPROTO_BRIDGE, &ebt_ulog_logger);
return 0;
out_target:
unregister_pernet_subsys(&ebt_ulog_net_ops);
out_pernet:
return ret;
}
static void __exit ebt_ulog_fini(void)
{
nf_log_unregister(&ebt_ulog_logger);
xt_unregister_target(&ebt_ulog_tg_reg);
unregister_pernet_subsys(&ebt_ulog_net_ops);
}
module_init(ebt_ulog_init);
module_exit(ebt_ulog_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
MODULE_DESCRIPTION("Ebtables: Packet logging to netlink using ULOG");
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