![Jörn Engel](/assets/img/avatar_default.png)
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
439 lines
12 KiB
C
439 lines
12 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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*
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* 2000/09/22 ulog-cprange feature added
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* 2001/01/04 in-kernel queue as proposed by Sebastian Zander
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* <zander@fokus.gmd.de>
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* 2001/01/30 per-rule nlgroup conflicts with global queue.
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* nlgroup now global (sysctl)
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* 2001/04/19 ulog-queue reworked, now fixed buffer size specified at
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* module loadtime -HW
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* 2002/07/07 remove broken nflog_rcv() function -HW
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* 2002/08/29 fix shifted/unshifted nlgroup bug -HW
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* 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen>
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* 2004/10/25 fix erroneous calculation of 'len' parameter to NLMSG_PUT
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* resulting in bogus 'error during NLMSG_PUT' messages.
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*
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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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*
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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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* ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
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*/
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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/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/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_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_ULOG.h>
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#include <net/sock.h>
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#include <linux/bitops.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("iptables userspace logging module");
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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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#if 0
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#define DEBUGP(format, args...) printk("%s:%s:" format, \
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__FILE__, __FUNCTION__ , ## args)
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#else
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#define DEBUGP(format, args...)
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#endif
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#define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
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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 int nflog = 1;
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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 ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
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static struct sock *nflognl; /* our socket */
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static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
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/* send one ulog_buff_t to userspace */
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static void ulog_send(unsigned int nlgroupnum)
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{
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ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
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if (timer_pending(&ub->timer)) {
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DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
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del_timer(&ub->timer);
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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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DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
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ub->qlen, nlgroupnum + 1);
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netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, 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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DEBUGP("ipt_ULOG: 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(data);
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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);
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if (!skb) {
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PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
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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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PRINTR("ipt_ULOG: can't even allocate %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 ipt_ulog_packet(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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/* 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) ||
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(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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}
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size = NLMSG_SPACE(sizeof(*pm) + copy_len);
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ub = &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(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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DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
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loginfo->qthreshold);
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/* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
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nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
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sizeof(*pm)+copy_len);
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ub->qlen++;
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pm = NLMSG_DATA(nlh);
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/* We might not have a timestamp, get one */
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if (skb->tstamp.off_sec == 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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pm->timestamp_sec = skb->tstamp.off_sec;
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pm->timestamp_usec = skb->tstamp.off_usec;
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pm->mark = skb->nfmark;
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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));
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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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else
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*(pm->prefix) = '\0';
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if (in && in->hard_header_len > 0
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&& skb->mac.raw != (void *) skb->nh.iph
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&& in->hard_header_len <= ULOG_MAC_LEN) {
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memcpy(pm->mac, skb->mac.raw, 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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else
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pm->indev_name[0] = '\0';
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if (out)
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strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
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else
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pm->outdev_name[0] = '\0';
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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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}
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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(groupnum);
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}
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spin_unlock_bh(&ulog_lock);
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return;
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nlmsg_failure:
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PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
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alloc_failure:
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PRINTR("ipt_ULOG: 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 ipt_ulog_target(struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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unsigned int hooknum,
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const struct xt_target *target,
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const void *targinfo, void *userinfo)
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{
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struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
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ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
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return IPT_CONTINUE;
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}
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static void ipt_logfn(unsigned int 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(hooknum, skb, in, out, &loginfo, prefix);
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}
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static int ipt_ulog_checkentry(const char *tablename,
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const void *e,
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const struct xt_target *target,
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void *targinfo,
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unsigned int targinfosize,
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unsigned int hookmask)
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{
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struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
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if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
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DEBUGP("ipt_ULOG: prefix term %i\n",
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loginfo->prefix[sizeof(loginfo->prefix) - 1]);
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return 0;
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}
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if (loginfo->qthreshold > ULOG_MAX_QLEN) {
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DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
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loginfo->qthreshold);
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return 0;
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}
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return 1;
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}
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static struct ipt_target ipt_ulog_reg = {
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.name = "ULOG",
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.target = ipt_ulog_target,
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.targetsize = sizeof(struct ipt_ulog_info),
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.checkentry = ipt_ulog_checkentry,
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.me = THIS_MODULE,
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};
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static struct nf_logger ipt_ulog_logger = {
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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 __init ipt_ulog_init(void)
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{
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int i;
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DEBUGP("ipt_ULOG: init module\n");
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if (nlbufsiz > 128*1024) {
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printk("Netlink buffer has to be <= 128kB\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 < ULOG_MAXNLGROUPS; i++) {
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init_timer(&ulog_buffers[i].timer);
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ulog_buffers[i].timer.function = ulog_timer;
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ulog_buffers[i].timer.data = i;
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}
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nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
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THIS_MODULE);
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if (!nflognl)
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return -ENOMEM;
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if (ipt_register_target(&ipt_ulog_reg) != 0) {
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sock_release(nflognl->sk_socket);
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return -EINVAL;
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}
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if (nflog)
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nf_log_register(PF_INET, &ipt_ulog_logger);
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return 0;
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}
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static void __exit ipt_ulog_fini(void)
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{
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ulog_buff_t *ub;
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int i;
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DEBUGP("ipt_ULOG: cleanup_module\n");
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if (nflog)
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nf_log_unregister_logger(&ipt_ulog_logger);
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ipt_unregister_target(&ipt_ulog_reg);
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sock_release(nflognl->sk_socket);
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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_buffers[i];
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if (timer_pending(&ub->timer)) {
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DEBUGP("timer was pending, deleting\n");
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del_timer(&ub->timer);
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}
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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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module_init(ipt_ulog_init);
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module_exit(ipt_ulog_fini);
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