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* netfilter module for userspace packet logging daemons
*
* (C) 2000-2002 by Harald Welte <laforge@gnumonks.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
*
* Released under the terms of the GPL
*
* This module accepts two parameters:
*
* nlbufsiz:
* The parameter specifies how big the buffer for each netlink multicast
* group is. e.g. If you say nlbufsiz=8192, up to eight kb of packets will
* get accumulated in the kernel until they are sent to userspace. It is
* NOT possible to allocate more than 128kB, and it is strongly discouraged,
* because atomically allocating 128kB inside the network rx softirq is not
* reliable. Please also keep in mind that this buffer size is allocated for
* each nlgroup you are using, so the total kernel memory usage increases
* by that factor.
*
* flushtimeout:
* Specify, after how many clock ticks (intel: 100 per second) the queue
* should be flushed even if it is not full yet.
*
* ipt_ULOG.c,v 1.15 2002/01/18 21:33:19 laforge Exp
*/
#include <linux/module.h>
#include <linux/version.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/socket.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_ULOG.h>
#include <linux/netfilter_ipv4/lockhelp.h>
#include <net/sock.h>
MODULE_LICENSE("GPL");
#define ULOG_NL_EVENT 111 /* Harald's favorite number */
#define ULOG_MAXNLGROUPS 32 /* numer of nlgroups */
#if 0
#define DEBUGP(format, args...) printk(__FILE__ ":" __FUNCTION__ ":" \
format, ## args)
#else
#define DEBUGP(format, args...)
#endif
#define PRINTR(format, args...) do { if (net_ratelimit()) printk(format, ## args); } while (0)
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("IP tables userspace logging module");
static unsigned int nlbufsiz = 4096;
MODULE_PARM(nlbufsiz, "i");
MODULE_PARM_DESC(nlbufsiz, "netlink buffer size");
static unsigned int flushtimeout = 10 * HZ;
MODULE_PARM(flushtimeout, "i");
MODULE_PARM_DESC(flushtimeout, "buffer flush timeout");
/* 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 size_t qlen; /* current length of multipart-nlmsg */
DECLARE_LOCK(ulog_lock); /* spinlock */
/* send one ulog_buff_t to userspace */
static void ulog_send(unsigned int nlgroup)
{
ulog_buff_t *ub = &ulog_buffers[nlgroup];
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_groups = nlgroup;
DEBUGP("ipt_ULOG: throwing %d packets to netlink mask %u\n",
ub->qlen, nlgroup);
netlink_broadcast(nflognl, ub->skb, 0, nlgroup, GFP_ATOMIC);
ub->qlen = 0;
ub->skb = NULL;
ub->lastnlh = NULL;
}
/* timer function to flush queue in ULOG_FLUSH_INTERVAL 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 */
LOCK_BH(&ulog_lock);
ulog_send(data);
UNLOCK_BH(&ulog_lock);
}
static void nflog_rcv(struct sock *sk, int len)
{
printk("ipt_ULOG:nflog_rcv() did receive netlink message ?!?\n");
}
struct sk_buff *ulog_alloc_skb(unsigned int size)
{
struct sk_buff *skb;
/* alloc skb which should be big enough for a whole
* multipart message. WARNING: has to be <= 131000
* due to slab allocator restrictions */
skb = alloc_skb(nlbufsiz, GFP_ATOMIC);
if (!skb) {
PRINTR("ipt_ULOG: can't alloc whole buffer %ub!\n",
nlbufsiz);
/* 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 unsigned int ipt_ulog_target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo, void *userinfo)
{
ulog_buff_t *ub;
ulog_packet_msg_t *pm;
size_t size, copy_len;
struct nlmsghdr *nlh;
struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
/* calculate the size of the skb needed */
if ((loginfo->copy_range == 0) ||
(loginfo->copy_range > (*pskb)->len)) {
copy_len = (*pskb)->len;
} else {
copy_len = loginfo->copy_range;
}
size = NLMSG_SPACE(sizeof(*pm) + copy_len);
ub = &ulog_buffers[loginfo->nl_group];
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(loginfo->nl_group);
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,
size - sizeof(*nlh));
ub->qlen++;
pm = NLMSG_DATA(nlh);
/* copy hook, prefix, timestamp, payload, etc. */
pm->data_len = copy_len;
pm->timestamp_sec = (*pskb)->stamp.tv_sec;
pm->timestamp_usec = (*pskb)->stamp.tv_usec;
pm->mark = (*pskb)->nfmark;
pm->hook = hooknum;
if (loginfo->prefix[0] != '\0')
strncpy(pm->prefix, loginfo->prefix, sizeof(pm->prefix));
else
*(pm->prefix) = '\0';
if (in && in->hard_header_len > 0
&& (*pskb)->mac.raw != (void *) (*pskb)->nh.iph
&& in->hard_header_len <= ULOG_MAC_LEN) {
memcpy(pm->mac, (*pskb)->mac.raw, in->hard_header_len);
pm->mac_len = in->hard_header_len;
}
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';
if (copy_len)
memcpy(pm->payload, (*pskb)->data, copy_len);
/* check if we are building multi-part messages */
if (ub->qlen > 1) {
ub->lastnlh->nlmsg_flags |= NLM_F_MULTI;
}
/* if threshold is reached, send message to userspace */
if (qlen >= loginfo->qthreshold) {
if (loginfo->qthreshold > 1)
nlh->nlmsg_type = NLMSG_DONE;
}
ub->lastnlh = nlh;
/* if timer isn't already running, start it */
if (!timer_pending(&ub->timer)) {
ub->timer.expires = jiffies + flushtimeout;
add_timer(&ub->timer);
}
UNLOCK_BH(&ulog_lock);
return IPT_CONTINUE;
nlmsg_failure:
PRINTR("ipt_ULOG: error during NLMSG_PUT\n");
alloc_failure:
PRINTR("ipt_ULOG: Error building netlink message\n");
UNLOCK_BH(&ulog_lock);
return IPT_CONTINUE;
}
static int ipt_ulog_checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hookmask)
{
struct ipt_ulog_info *loginfo = (struct ipt_ulog_info *) targinfo;
if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ulog_info))) {
DEBUGP("ipt_ULOG: targinfosize %u != 0\n", targinfosize);
return 0;
}
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 =
{ {NULL, NULL}, "ULOG", ipt_ulog_target, ipt_ulog_checkentry, NULL,
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++) {
memset(&ulog_buffers[i], 0, sizeof(ulog_buff_t));
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, nflog_rcv);
if (!nflognl)
return -ENOMEM;
if (ipt_register_target(&ipt_ulog_reg) != 0) {
sock_release(nflognl->socket);
return -EINVAL;
}
return 0;
}
static void __exit fini(void)
{
DEBUGP("ipt_ULOG: cleanup_module\n");
ipt_unregister_target(&ipt_ulog_reg);
sock_release(nflognl->socket);
}
module_init(init);
module_exit(fini);
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