/*
* netfilter module for userspace packet logging daemons
*
* (C) 2000-2004 by Harald Welte <laforge@netfilter.org>
*
* 2000/09/22 ulog-cprange feature added
* 2001/01/04 in-kernel queue as proposed by Sebastian Zander
* <zander@fokus.gmd.de>
* 2001/01/30 per-rule nlgroup conflicts with global queue.
* nlgroup now global (sysctl)
* 2001/04/19 ulog-queue reworked, now fixed buffer size specified at
* module loadtime -HW
* 2002/07/07 remove broken nflog_rcv() function -HW
* 2002/08/29 fix shifted/unshifted nlgroup bug -HW
* 2002/10/30 fix uninitialized mac_len field - <Anders K. Pedersen>
* 2004/10/25 fix erroneous calculation of 'len' parameter to NLMSG_PUT
* resulting in bogus 'error during NLMSG_PUT' messages.
*
* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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.
*
* Actually you should use nlbufsiz a bit smaller than PAGE_SIZE, since
* nlbufsiz is used with alloc_skb, which adds another
* sizeof(struct skb_shared_info). Use NLMSG_GOODSIZE instead.
*
* flushtimeout:
* Specify, after how many hundredths of a second the queue should be
* flushed even if it is not full yet.
*
* ipt_ULOG.c,v 1.22 2002/10/30 09:07:31 laforge Exp
*/
#include <linux/module.h>
#include <linux/config.h>
#include <linux/spinlock.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/netlink.h>
#include <linux/netdevice.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ULOG.h>
#include <net/sock.h>
#include <linux/bitops.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("iptables userspace logging module");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NFLOG);
#define ULOG_NL_EVENT 111 /* Harald's favorite number */
#define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
#if 0
#define DEBUGP(format, args...) printk("%s:%s:" format, \
__FILE__, __FUNCTION__ , ## args)
#else
#define DEBUGP(format, args...)
#endif
#define PRINTR(format, args...) do { if (net_ratelimit()) printk(format , ## args); } while (0)
static unsigned int nlbufsiz = NLMSG_GOODSIZE;
module_param(nlbufsiz, uint, 0400);
MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
static unsigned int flushtimeout = 10;
module_param(flushtimeout, uint, 0600);
MODULE_PARM_DESC(flushtimeout, "buffer flush timeout (hundredths of a second)");
static int nflog = 1;
module_param(nflog, bool, 0400);
MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
/* global data structures */
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 */
} ulog_buff_t;
static ulog_buff_t ulog_buffers[ULOG_MAXNLGROUPS]; /* array of buffers */
static struct sock *nflognl; /* our socket */
static DEFINE_SPINLOCK(ulog_lock); /* spinlock */
/* send one ulog_buff_t to userspace */
static void ulog_send(unsigned int nlgroupnum)
{
ulog_buff_t *ub = &ulog_buffers[nlgroupnum];
if (timer_pending(&ub->timer)) {
DEBUGP("ipt_ULOG: ulog_send: timer was pending, deleting\n");
del_timer(&ub->timer);
}
/* last nlmsg needs NLMSG_DONE */
if (ub->qlen > 1)
ub->lastnlh->nlmsg_type = NLMSG_DONE;
NETLINK_CB(ub->skb).dst_group = nlgroupnum + 1;
DEBUGP("ipt_ULOG: throwing %d packets to netlink group %u\n",
ub->qlen, nlgroupnum + 1);
netlink_broadcast(nflognl, ub->skb, 0, nlgroupnum + 1, GFP_ATOMIC);
ub->qlen = 0;
ub->skb = NULL;
ub->lastnlh = NULL;
}
/* timer function to flush queue in flushtimeout time */
static void ulog_timer(unsigned long data)
{
DEBUGP("ipt_ULOG: timer function called, calling ulog_send\n");
/* lock to protect against somebody modifying our structure
* from ipt_ulog_target at the same time */
spin_lock_bh(&ulog_lock);
ulog_send(data);
spin_unlock_bh(&ulog_lock);
}
static struct sk_buff *ulog_alloc_skb(unsigned int size)
{
struct sk_buff *skb;
unsigned int n;
/* alloc skb which should be big enough for a whole
* multipart message. WARNING: has to be <= 131000
* due to slab allocator restrictions */
n = max(size, nlbufsiz);
skb = alloc_skb(n, GFP_ATOMIC);
if (!skb) {
PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n", n);
if (n > size) {
/* try to allocate only as much as we need for
* current packet */
skb = alloc_skb(size, GFP_ATOMIC);
if (!skb)
PRINTR("ipt_ULOG: can't even allocate %ub\n",
size);
}
}
return skb;
}
static void ipt_ulog_packet(unsigned int hooknum,
const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct ipt_ulog_info *loginfo,
const char *prefix)
{
ulog_buff_t *ub;
ulog_packet_msg_t *pm;
size_t size, copy_len;
struct nlmsghdr *nlh;
/* ffs == find first bit set, necessary because userspace
* is already shifting groupnumber, but we need unshifted.
* ffs() returns [1..32], we need [0..31] */
unsigned int groupnum = ffs(loginfo->nl_group) - 1;
/* calculate the size of the skb needed */
if ((loginfo->copy_range == 0) ||
(loginfo->copy_range > skb->len)) {
copy_len = skb->len;
} else {
copy_len = loginfo->copy_range;
}
size = NLMSG_SPACE(sizeof(*pm) + copy_len);
ub = &ulog_buffers[groupnum];
spin_lock_bh(&ulog_lock);
if (!ub->skb) {
if (!(ub->skb = ulog_alloc_skb(size)))
goto alloc_failure;
} else if (ub->qlen >= loginfo->qthreshold ||
size > skb_tailroom(ub->skb)) {
/* either the queue len is too high or we don't have
* enough room in nlskb left. send it to userspace. */
ulog_send(groupnum);
if (!(ub->skb = ulog_alloc_skb(size)))
goto alloc_failure;
}
DEBUGP("ipt_ULOG: qlen %d, qthreshold %d\n", ub->qlen,
loginfo->qthreshold);
/* NLMSG_PUT contains a hidden goto nlmsg_failure !!! */
nlh = NLMSG_PUT(ub->skb, 0, ub->qlen, ULOG_NL_EVENT,
sizeof(*pm)+copy_len);
ub->qlen++;
pm = NLMSG_DATA(nlh);
/* We might not have a timestamp, get one */
if (skb->tstamp.off_sec == 0)
__net_timestamp((struct sk_buff *)skb);
/* copy hook, prefix, timestamp, payload, etc. */
pm->data_len = copy_len;
pm->timestamp_sec = skb->tstamp.off_sec;
pm->timestamp_usec = skb->tstamp.off_usec;
pm->mark = skb->nfmark;
pm->hook = hooknum;
if (prefix != NULL)
strncpy(pm->prefix, prefix, sizeof(pm->prefix));
else if (loginfo->prefix[0] != '\0')
strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
else
*(pm->prefix) = '\0';
if (in && in->hard_header_len > 0
&& skb->mac.raw != (void *) skb->nh.iph
&& in->hard_header_len <= ULOG_MAC_LEN) {
memcpy(pm->mac, skb->mac.raw, in->hard_header_len);
pm->mac_len = in->hard_header_len;
} else
pm->mac_len = 0;
if (in)
strncpy(pm->indev_name, in->name, sizeof(pm->indev_name));
else
pm->indev_name[0] = '\0';
if (out)
strncpy(pm->outdev_name, out->name, sizeof(pm->outdev_name));
else
pm->outdev_name[0] = '\0';
/* copy_len <= skb->len, so can't fail. */
if (skb_copy_bits(skb, 0, pm->payload, copy_len) < 0)
BUG();
/* check if we are building multi-part messages */
if (ub->qlen > 1) {
ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
}
ub->lastnlh = nlh;
/* if timer isn't already running, start it */
if (!timer_pending(&ub->timer)) {
ub->timer.expires = jiffies + flushtimeout * HZ / 100;
add_timer(&ub->timer);
}
/* if threshold is reached, send message to userspace */
if (ub->qlen >= loginfo->qthreshold) {
if (loginfo->qthreshold > 1)
nlh->nlmsg_type = NLMSG_DONE;
ulog_send(groupnum);
}
spin_unlock_bh(&ulog_lock);
return;
nlmsg_failure:
PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
alloc_failure:
PRINTR("ipt_ULOG: Error building netlink message\n");
spin_unlock_bh(&ulog_lock);
}
static unsigned int ipt_ulog_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const struct xt_target *target,
const void *targinfo, void *userinfo)
{
struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
ipt_ulog_packet(hooknum, *pskb, in, out, loginfo, NULL);
return IPT_CONTINUE;
}
static void ipt_logfn(unsigned int 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 ipt_ulog_info loginfo;
if (!li || li->type != NF_LOG_TYPE_ULOG) {
loginfo.nl_group = ULOG_DEFAULT_NLGROUP;
loginfo.copy_range = 0;
loginfo.qthreshold = ULOG_DEFAULT_QTHRESHOLD;
loginfo.prefix[0] = '\0';
} else {
loginfo.nl_group = li->u.ulog.group;
loginfo.copy_range = li->u.ulog.copy_len;
loginfo.qthreshold = li->u.ulog.qthreshold;
strlcpy(loginfo.prefix, prefix, sizeof(loginfo.prefix));
}
ipt_ulog_packet(hooknum, skb, in, out, &loginfo, prefix);
}
static int ipt_ulog_checkentry(const char *tablename,
const void *e,
const struct xt_target *target,
void *targinfo,
unsigned int targinfosize,
unsigned int hookmask)
{
struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
if (loginfo->prefix[sizeof(loginfo->prefix) - 1] != '\0') {
DEBUGP("ipt_ULOG: prefix term %i\n",
loginfo->prefix[sizeof(loginfo->prefix) - 1]);
return 0;
}
if (loginfo->qthreshold > ULOG_MAX_QLEN) {
DEBUGP("ipt_ULOG: queue threshold %i > MAX_QLEN\n",
loginfo->qthreshold);
return 0;
}
return 1;
}
static struct ipt_target ipt_ulog_reg = {
.name = "ULOG",
.target = ipt_ulog_target,
.targetsize = sizeof(struct ipt_ulog_info),
.checkentry = ipt_ulog_checkentry,
.me = THIS_MODULE,
};
static struct nf_logger ipt_ulog_logger = {
.name = "ipt_ULOG",
.logfn = ipt_logfn,
.me = THIS_MODULE,
};
static int __init init(void)
{
int i;
DEBUGP("ipt_ULOG: init module\n");
if (nlbufsiz > 128*1024) {
printk("Netlink buffer has to be <= 128kB\n");
return -EINVAL;
}
/* initialize ulog_buffers */
for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
init_timer(&ulog_buffers[i].timer);
ulog_buffers[i].timer.function = ulog_timer;
ulog_buffers[i].timer.data = i;
}
nflognl = netlink_kernel_create(NETLINK_NFLOG, ULOG_MAXNLGROUPS, NULL,
THIS_MODULE);
if (!nflognl)
return -ENOMEM;
if (ipt_register_target(&ipt_ulog_reg) != 0) {
sock_release(nflognl->sk_socket);
return -EINVAL;
}
if (nflog)
nf_log_register(PF_INET, &ipt_ulog_logger);
return 0;
}
static void __exit fini(void)
{
ulog_buff_t *ub;
int i;
DEBUGP("ipt_ULOG: cleanup_module\n");
if (nflog)
nf_log_unregister_logger(&ipt_ulog_logger);
ipt_unregister_target(&ipt_ulog_reg);
sock_release(nflognl->sk_socket);
/* remove pending timers and free allocated skb's */
for (i = 0; i < ULOG_MAXNLGROUPS; i++) {
ub = &ulog_buffers[i];
if (timer_pending(&ub->timer)) {
DEBUGP("timer was pending, deleting\n");
del_timer(&ub->timer);
}
if (ub->skb) {
kfree_skb(ub->skb);
ub->skb = NULL;
}
}
}
module_init(init);
module_exit(fini);
