![Mathias Krause](/assets/img/avatar_default.png)
The ulog messages leak heap bytes by the means of padding bytes and incompletely filled string arrays. Fix those by memset(0)'ing the whole struct before filling it. Signed-off-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
499 lines
13 KiB
C
499 lines
13 KiB
C
/*
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* netfilter module for userspace packet logging daemons
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*
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* (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
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* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2005-2007 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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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* Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
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* nlbufsiz is used with alloc_skb, which adds another
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* sizeof(struct skb_shared_info). Use NLMSG_GOODSIZE instead.
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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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/socket.h>
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#include <linux/slab.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 <net/netlink.h>
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#include <linux/netdevice.h>
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#include <linux/mm.h>
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#include <linux/moduleparam.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ipt_ULOG.h>
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#include <net/netfilter/nf_log.h>
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#include <net/netns/generic.h>
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#include <net/sock.h>
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#include <linux/bitops.h>
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#include <asm/unaligned.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
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MODULE_DESCRIPTION("Xtables: packet logging to netlink using ULOG");
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MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
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#define ULOG_NL_EVENT 111 /* Harald's favorite number */
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#define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
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static unsigned int nlbufsiz = NLMSG_GOODSIZE;
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module_param(nlbufsiz, uint, 0400);
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MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
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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 of a second)");
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static bool nflog = true;
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module_param(nflog, bool, 0400);
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MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
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/* global data structures */
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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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} ulog_buff_t;
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static int ulog_net_id __read_mostly;
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struct ulog_net {
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unsigned int nlgroup[ULOG_MAXNLGROUPS];
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ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS];
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struct sock *nflognl;
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spinlock_t lock;
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};
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static struct ulog_net *ulog_pernet(struct net *net)
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{
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return net_generic(net, ulog_net_id);
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}
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/* send one ulog_buff_t to userspace */
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static void ulog_send(struct ulog_net *ulog, unsigned int nlgroupnum)
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{
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ulog_buff_t *ub = &ulog->ulog_buffers[nlgroupnum];
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pr_debug("ulog_send: timer is deleting\n");
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del_timer(&ub->timer);
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if (!ub->skb) {
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pr_debug("ulog_send: nothing to send\n");
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return;
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}
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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 = nlgroupnum + 1;
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pr_debug("throwing %d packets to netlink group %u\n",
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ub->qlen, nlgroupnum + 1);
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netlink_broadcast(ulog->nflognl, ub->skb, 0, nlgroupnum + 1,
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GFP_ATOMIC);
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ub->qlen = 0;
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ub->skb = NULL;
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ub->lastnlh = 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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unsigned int groupnum = *((unsigned int *)data);
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struct ulog_net *ulog = container_of((void *)data,
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struct ulog_net,
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nlgroup[groupnum]);
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pr_debug("timer function called, calling ulog_send\n");
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/* lock to protect against somebody modifying our structure
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* from ipt_ulog_target at the same time */
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spin_lock_bh(&ulog->lock);
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ulog_send(ulog, groupnum);
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spin_unlock_bh(&ulog->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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/* alloc skb which should be big enough for a whole
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* multipart message. WARNING: has to be <= 131000
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* due to slab allocator restrictions */
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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 %ub\n", 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 ipt_ulog_packet(struct net *net,
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unsigned int hooknum,
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const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const struct ipt_ulog_info *loginfo,
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const char *prefix)
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{
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ulog_buff_t *ub;
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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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struct timeval tv;
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struct ulog_net *ulog = ulog_pernet(net);
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/* ffs == find first bit set, necessary because userspace
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* is already shifting groupnumber, but we need unshifted.
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* ffs() returns [1..32], we need [0..31] */
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unsigned int groupnum = ffs(loginfo->nl_group) - 1;
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/* calculate the size of the skb needed */
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if (loginfo->copy_range == 0 || loginfo->copy_range > skb->len)
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copy_len = skb->len;
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else
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copy_len = loginfo->copy_range;
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size = nlmsg_total_size(sizeof(*pm) + copy_len);
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ub = &ulog->ulog_buffers[groupnum];
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spin_lock_bh(&ulog->lock);
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if (!ub->skb) {
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if (!(ub->skb = ulog_alloc_skb(size)))
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goto alloc_failure;
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} else if (ub->qlen >= loginfo->qthreshold ||
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size > skb_tailroom(ub->skb)) {
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/* either the queue len is too high or we don't have
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* enough room in nlskb left. send it to userspace. */
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ulog_send(ulog, groupnum);
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if (!(ub->skb = ulog_alloc_skb(size)))
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goto alloc_failure;
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}
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pr_debug("qlen %d, qthreshold %Zu\n", ub->qlen, loginfo->qthreshold);
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nlh = nlmsg_put(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
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sizeof(*pm)+copy_len, 0);
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if (!nlh) {
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pr_debug("error during nlmsg_put\n");
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goto out_unlock;
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}
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ub->qlen++;
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pm = nlmsg_data(nlh);
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memset(pm, 0, sizeof(*pm));
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/* We might not have a timestamp, get one */
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if (skb->tstamp.tv64 == 0)
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__net_timestamp((struct sk_buff *)skb);
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/* copy hook, prefix, timestamp, payload, etc. */
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pm->data_len = copy_len;
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tv = ktime_to_timeval(skb->tstamp);
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put_unaligned(tv.tv_sec, &pm->timestamp_sec);
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put_unaligned(tv.tv_usec, &pm->timestamp_usec);
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put_unaligned(skb->mark, &pm->mark);
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pm->hook = hooknum;
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if (prefix != NULL) {
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strncpy(pm->prefix, prefix, sizeof(pm->prefix) - 1);
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pm->prefix[sizeof(pm->prefix) - 1] = '\0';
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}
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else if (loginfo->prefix[0] != '\0')
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strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
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if (in && in->hard_header_len > 0 &&
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skb->mac_header != skb->network_header &&
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in->hard_header_len <= ULOG_MAC_LEN) {
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memcpy(pm->mac, skb_mac_header(skb), in->hard_header_len);
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pm->mac_len = in->hard_header_len;
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} else
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pm->mac_len = 0;
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if (in)
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strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
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if (out)
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strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
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/* copy_len <= skb->len, so can't fail. */
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if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
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BUG();
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/* check if we are building multi-part messages */
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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 timer isn't already running, start it */
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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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/* if threshold is reached, send message to userspace */
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if (ub->qlen >= loginfo->qthreshold) {
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if (loginfo->qthreshold > 1)
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nlh->nlmsg_type = NLMSG_DONE;
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ulog_send(ulog, groupnum);
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}
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out_unlock:
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spin_unlock_bh(&ulog->lock);
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return;
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alloc_failure:
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pr_debug("Error building netlink message\n");
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spin_unlock_bh(&ulog->lock);
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}
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static unsigned int
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ulog_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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struct net *net = dev_net(par->in ? par->in : par->out);
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ipt_ulog_packet(net, par->hooknum, skb, par->in, par->out,
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par->targinfo, NULL);
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return XT_CONTINUE;
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}
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static void ipt_logfn(struct net *net,
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u_int8_t pf,
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unsigned int hooknum,
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const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const struct nf_loginfo *li,
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const char *prefix)
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{
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struct ipt_ulog_info loginfo;
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if (!li || li->type != NF_LOG_TYPE_ULOG) {
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loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
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loginfo.copy_range = 0;
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loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
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loginfo.prefix[0] = '\0';
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} else {
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loginfo.nl_group = li->u.ulog.group;
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loginfo.copy_range = 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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ipt_ulog_packet(net, hooknum, skb, in, out, &loginfo, prefix);
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}
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static int ulog_tg_check(const struct xt_tgchk_param *par)
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{
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const struct ipt_ulog_info *loginfo = par->targinfo;
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if (!par->net->xt.ulog_warn_deprecated) {
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pr_info("ULOG is deprecated and it will be removed soon, "
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"use NFLOG instead\n");
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par->net->xt.ulog_warn_deprecated = true;
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}
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if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
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pr_debug("prefix not null-terminated\n");
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return -EINVAL;
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}
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if (loginfo->qthreshold > ULOG_MAX_QLEN) {
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pr_debug("queue threshold %Zu > MAX_QLEN\n",
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loginfo->qthreshold);
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return -EINVAL;
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}
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return 0;
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}
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#ifdef CONFIG_COMPAT
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struct compat_ipt_ulog_info {
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compat_uint_t nl_group;
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compat_size_t copy_range;
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compat_size_t qthreshold;
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char prefix[ULOG_PREFIX_LEN];
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};
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static void ulog_tg_compat_from_user(void *dst, const void *src)
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{
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const struct compat_ipt_ulog_info *cl = src;
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struct ipt_ulog_info l = {
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.nl_group = cl->nl_group,
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.copy_range = cl->copy_range,
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.qthreshold = cl->qthreshold,
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};
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memcpy(l.prefix, cl->prefix, sizeof(l.prefix));
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memcpy(dst, &l, sizeof(l));
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}
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static int ulog_tg_compat_to_user(void __user *dst, const void *src)
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{
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const struct ipt_ulog_info *l = src;
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struct compat_ipt_ulog_info cl = {
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.nl_group = l->nl_group,
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.copy_range = l->copy_range,
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.qthreshold = l->qthreshold,
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};
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memcpy(cl.prefix, l->prefix, sizeof(cl.prefix));
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return copy_to_user(dst, &cl, sizeof(cl)) ? -EFAULT : 0;
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}
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#endif /* CONFIG_COMPAT */
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static struct xt_target ulog_tg_reg __read_mostly = {
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.name = "ULOG",
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.family = NFPROTO_IPV4,
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.target = ulog_tg,
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.targetsize = sizeof(struct ipt_ulog_info),
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.checkentry = ulog_tg_check,
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#ifdef CONFIG_COMPAT
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.compatsize = sizeof(struct compat_ipt_ulog_info),
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.compat_from_user = ulog_tg_compat_from_user,
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.compat_to_user = ulog_tg_compat_to_user,
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#endif
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.me = THIS_MODULE,
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};
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static struct nf_logger ipt_ulog_logger __read_mostly = {
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.name = "ipt_ULOG",
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.logfn = ipt_logfn,
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.me = THIS_MODULE,
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};
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static int __net_init ulog_tg_net_init(struct net *net)
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{
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int i;
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struct ulog_net *ulog = ulog_pernet(net);
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struct netlink_kernel_cfg cfg = {
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.groups = ULOG_MAXNLGROUPS,
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};
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spin_lock_init(&ulog->lock);
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/* initialize ulog_buffers */
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for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
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ulog->nlgroup[i] = i;
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setup_timer(&ulog->ulog_buffers[i].timer, ulog_timer,
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(unsigned long)&ulog->nlgroup[i]);
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}
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ulog->nflognl = netlink_kernel_create(net, NETLINK_NFLOG, &cfg);
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if (!ulog->nflognl)
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return -ENOMEM;
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if (nflog)
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nf_log_set(net, NFPROTO_IPV4, &ipt_ulog_logger);
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return 0;
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}
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static void __net_exit ulog_tg_net_exit(struct net *net)
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{
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ulog_buff_t *ub;
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int i;
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struct ulog_net *ulog = ulog_pernet(net);
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if (nflog)
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nf_log_unset(net, &ipt_ulog_logger);
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netlink_kernel_release(ulog->nflognl);
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/* remove pending timers and free allocated skb's */
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for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
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ub = &ulog->ulog_buffers[i];
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pr_debug("timer is deleting\n");
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del_timer(&ub->timer);
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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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}
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}
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static struct pernet_operations ulog_tg_net_ops = {
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.init = ulog_tg_net_init,
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.exit = ulog_tg_net_exit,
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.id = &ulog_net_id,
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.size = sizeof(struct ulog_net),
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};
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static int __init ulog_tg_init(void)
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{
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int ret;
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pr_debug("init module\n");
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if (nlbufsiz > 128*1024) {
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pr_warn("Netlink buffer has to be <= 128kB\n");
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return -EINVAL;
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}
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ret = register_pernet_subsys(&ulog_tg_net_ops);
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if (ret)
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goto out_pernet;
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ret = xt_register_target(&ulog_tg_reg);
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if (ret < 0)
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goto out_target;
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if (nflog)
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nf_log_register(NFPROTO_IPV4, &ipt_ulog_logger);
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return 0;
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out_target:
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unregister_pernet_subsys(&ulog_tg_net_ops);
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out_pernet:
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return ret;
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}
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static void __exit ulog_tg_exit(void)
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{
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pr_debug("cleanup_module\n");
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|
if (nflog)
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nf_log_unregister(&ipt_ulog_logger);
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xt_unregister_target(&ulog_tg_reg);
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|
unregister_pernet_subsys(&ulog_tg_net_ops);
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|
}
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module_init(ulog_tg_init);
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|
module_exit(ulog_tg_exit);
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