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