ipt_LOG.c
/*
* This is a module which is used for logging packets.
*/
/* (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.
*/
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/route.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_LOG.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables syslog logging module");
static unsigned int nflog = 1;
module_param(nflog, int, 0400);
MODULE_PARM_DESC(nflog, "register as internal netfilter logging module");
#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
/* Use lock to serialize, so printks don't overlap */
static DEFINE_SPINLOCK(log_lock);
/* One level of recursion won't kill us */
static void dump_packet(const struct ipt_log_info *info,
const struct sk_buff *skb,
unsigned int iphoff)
{
struct iphdr _iph, *ih;
ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
if (ih == NULL) {
printk("TRUNCATED");
return;
}
/* Important fields:
* TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
/* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
printk("SRC=%u.%u.%u.%u DST=%u.%u.%u.%u ",
NIPQUAD(ih->saddr), NIPQUAD(ih->daddr));
/* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
printk("LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
/* Max length: 6 "CE DF MF " */
if (ntohs(ih->frag_off) & IP_CE)
printk("CE ");
if (ntohs(ih->frag_off) & IP_DF)
printk("DF ");
if (ntohs(ih->frag_off) & IP_MF)
printk("MF ");
/* Max length: 11 "FRAG:65535 " */
if (ntohs(ih->frag_off) & IP_OFFSET)
printk("FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
if ((info->logflags & IPT_LOG_IPOPT)
&& ih->ihl * 4 > sizeof(struct iphdr)) {
unsigned char _opt[4 * 15 - sizeof(struct iphdr)], *op;
unsigned int i, optsize;
optsize = ih->ihl * 4 - sizeof(struct iphdr);
op = skb_header_pointer(skb, iphoff+sizeof(_iph),
optsize, _opt);
if (op == NULL) {
printk("TRUNCATED");
return;
}
/* Max length: 127 "OPT (" 15*4*2chars ") " */
printk("OPT (");
for (i = 0; i < optsize; i++)
printk("%02X", op[i]);
printk(") ");
}
switch (ih->protocol) {
case IPPROTO_TCP: {
struct tcphdr _tcph, *th;
/* Max length: 10 "PROTO=TCP " */
printk("PROTO=TCP ");
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
sizeof(_tcph), &_tcph);
if (th == NULL) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Max length: 20 "SPT=65535 DPT=65535 " */
printk("SPT=%u DPT=%u ",
ntohs(th->source), ntohs(th->dest));
/* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
if (info->logflags & IPT_LOG_TCPSEQ)
printk("SEQ=%u ACK=%u ",
ntohl(th->seq), ntohl(th->ack_seq));
/* Max length: 13 "WINDOW=65535 " */
printk("WINDOW=%u ", ntohs(th->window));
/* Max length: 9 "RES=0x3F " */
printk("RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
/* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
if (th->cwr)
printk("CWR ");
if (th->ece)
printk("ECE ");
if (th->urg)
printk("URG ");
if (th->ack)
printk("ACK ");
if (th->psh)
printk("PSH ");
if (th->rst)
printk("RST ");
if (th->syn)
printk("SYN ");
if (th->fin)
printk("FIN ");
/* Max length: 11 "URGP=65535 " */
printk("URGP=%u ", ntohs(th->urg_ptr));
if ((info->logflags & IPT_LOG_TCPOPT)
&& th->doff * 4 > sizeof(struct tcphdr)) {
unsigned char _opt[4 * 15 - sizeof(struct tcphdr)];
unsigned char *op;
unsigned int i, optsize;
optsize = th->doff * 4 - sizeof(struct tcphdr);
op = skb_header_pointer(skb,
iphoff+ih->ihl*4+sizeof(_tcph),
optsize, _opt);
if (op == NULL) {
printk("TRUNCATED");
return;
}
/* Max length: 127 "OPT (" 15*4*2chars ") " */
printk("OPT (");
for (i = 0; i < optsize; i++)
printk("%02X", op[i]);
printk(") ");
}
break;
}
case IPPROTO_UDP: {
struct udphdr _udph, *uh;
/* Max length: 10 "PROTO=UDP " */
printk("PROTO=UDP ");
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
sizeof(_udph), &_udph);
if (uh == NULL) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Max length: 20 "SPT=65535 DPT=65535 " */
printk("SPT=%u DPT=%u LEN=%u ",
ntohs(uh->source), ntohs(uh->dest),
ntohs(uh->len));
break;
}
case IPPROTO_ICMP: {
struct icmphdr _icmph, *ich;
static size_t required_len[NR_ICMP_TYPES+1]
= { [ICMP_ECHOREPLY] = 4,
[ICMP_DEST_UNREACH]
= 8 + sizeof(struct iphdr),
[ICMP_SOURCE_QUENCH]
= 8 + sizeof(struct iphdr),
[ICMP_REDIRECT]
= 8 + sizeof(struct iphdr),
[ICMP_ECHO] = 4,
[ICMP_TIME_EXCEEDED]
= 8 + sizeof(struct iphdr),
[ICMP_PARAMETERPROB]
= 8 + sizeof(struct iphdr),
[ICMP_TIMESTAMP] = 20,
[ICMP_TIMESTAMPREPLY] = 20,
[ICMP_ADDRESS] = 12,
[ICMP_ADDRESSREPLY] = 12 };
/* Max length: 11 "PROTO=ICMP " */
printk("PROTO=ICMP ");
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
sizeof(_icmph), &_icmph);
if (ich == NULL) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Max length: 18 "TYPE=255 CODE=255 " */
printk("TYPE=%u CODE=%u ", ich->type, ich->code);
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
if (ich->type <= NR_ICMP_TYPES
&& required_len[ich->type]
&& skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
switch (ich->type) {
case ICMP_ECHOREPLY:
case ICMP_ECHO:
/* Max length: 19 "ID=65535 SEQ=65535 " */
printk("ID=%u SEQ=%u ",
ntohs(ich->un.echo.id),
ntohs(ich->un.echo.sequence));
break;
case ICMP_PARAMETERPROB:
/* Max length: 14 "PARAMETER=255 " */
printk("PARAMETER=%u ",
ntohl(ich->un.gateway) >> 24);
break;
case ICMP_REDIRECT:
/* Max length: 24 "GATEWAY=255.255.255.255 " */
printk("GATEWAY=%u.%u.%u.%u ",
NIPQUAD(ich->un.gateway));
/* Fall through */
case ICMP_DEST_UNREACH:
case ICMP_SOURCE_QUENCH:
case ICMP_TIME_EXCEEDED:
/* Max length: 3+maxlen */
if (!iphoff) { /* Only recurse once. */
printk("[");
dump_packet(info, skb,
iphoff + ih->ihl*4+sizeof(_icmph));
printk("] ");
}
/* Max length: 10 "MTU=65535 " */
if (ich->type == ICMP_DEST_UNREACH
&& ich->code == ICMP_FRAG_NEEDED)
printk("MTU=%u ", ntohs(ich->un.frag.mtu));
}
break;
}
/* Max Length */
case IPPROTO_AH: {
struct ip_auth_hdr _ahdr, *ah;
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 9 "PROTO=AH " */
printk("PROTO=AH ");
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
sizeof(_ahdr), &_ahdr);
if (ah == NULL) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Length: 15 "SPI=0xF1234567 " */
printk("SPI=0x%x ", ntohl(ah->spi));
break;
}
case IPPROTO_ESP: {
struct ip_esp_hdr _esph, *eh;
/* Max length: 10 "PROTO=ESP " */
printk("PROTO=ESP ");
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
sizeof(_esph), &_esph);
if (eh == NULL) {
printk("INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Length: 15 "SPI=0xF1234567 " */
printk("SPI=0x%x ", ntohl(eh->spi));
break;
}
/* Max length: 10 "PROTO 255 " */
default:
printk("PROTO=%u ", ih->protocol);
}
/* Max length: 15 "UID=4294967295 " */
if ((info->logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
read_lock_bh(&skb->sk->sk_callback_lock);
if (skb->sk->sk_socket && skb->sk->sk_socket->file)
printk("UID=%u ", skb->sk->sk_socket->file->f_uid);
read_unlock_bh(&skb->sk->sk_callback_lock);
}
/* Proto Max log string length */
/* IP: 40+46+6+11+127 = 230 */
/* TCP: 10+max(25,20+30+13+9+32+11+127) = 252 */
/* UDP: 10+max(25,20) = 35 */
/* ICMP: 11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */
/* ESP: 10+max(25)+15 = 50 */
/* AH: 9+max(25)+15 = 49 */
/* unknown: 10 */
/* (ICMP allows recursion one level deep) */
/* maxlen = IP + ICMP + IP + max(TCP,UDP,ICMP,unknown) */
/* maxlen = 230+ 91 + 230 + 252 = 803 */
}
static void
ipt_log_packet(unsigned int hooknum,
const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct ipt_log_info *loginfo,
const char *level_string,
const char *prefix)
{
spin_lock_bh(&log_lock);
printk(level_string);
printk("%sIN=%s OUT=%s ",
prefix == NULL ? loginfo->prefix : prefix,
in ? in->name : "",
out ? out->name : "");
#ifdef CONFIG_BRIDGE_NETFILTER
if (skb->nf_bridge) {
struct net_device *physindev = skb->nf_bridge->physindev;
struct net_device *physoutdev = skb->nf_bridge->physoutdev;
if (physindev && in != physindev)
printk("PHYSIN=%s ", physindev->name);
if (physoutdev && out != physoutdev)
printk("PHYSOUT=%s ", physoutdev->name);
}
#endif
if (in && !out) {
/* MAC logging for input chain only. */
printk("MAC=");
if (skb->dev && skb->dev->hard_header_len
&& skb->mac.raw != (void*)skb->nh.iph) {
int i;
unsigned char *p = skb->mac.raw;
for (i = 0; i < skb->dev->hard_header_len; i++,p++)
printk("%02x%c", *p,
i==skb->dev->hard_header_len - 1
? ' ':':');
} else
printk(" ");
}
dump_packet(loginfo, skb, 0);
printk("\n");
spin_unlock_bh(&log_lock);
}
static unsigned int
ipt_log_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const void *targinfo,
void *userinfo)
{
const struct ipt_log_info *loginfo = targinfo;
char level_string[4] = "< >";
level_string[1] = '0' + (loginfo->level % 8);
ipt_log_packet(hooknum, *pskb, in, out, loginfo, level_string, NULL);
return IPT_CONTINUE;
}
static void
ipt_logfn(unsigned int hooknum,
const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const char *prefix)
{
struct ipt_log_info loginfo = {
.level = 0,
.logflags = IPT_LOG_MASK,
.prefix = ""
};
ipt_log_packet(hooknum, skb, in, out, &loginfo, KERN_WARNING, prefix);
}
static int ipt_log_checkentry(const char *tablename,
const struct ipt_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const struct ipt_log_info *loginfo = targinfo;
if (targinfosize != IPT_ALIGN(sizeof(struct ipt_log_info))) {
DEBUGP("LOG: targinfosize %u != %u\n",
targinfosize, IPT_ALIGN(sizeof(struct ipt_log_info)));
return 0;
}
if (loginfo->level >= 8) {
DEBUGP("LOG: level %u >= 8\n", loginfo->level);
return 0;
}
if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
DEBUGP("LOG: prefix term %i\n",
loginfo->prefix[sizeof(loginfo->prefix)-1]);
return 0;
}
return 1;
}
static struct ipt_target ipt_log_reg = {
.name = "LOG",
.target = ipt_log_target,
.checkentry = ipt_log_checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
if (ipt_register_target(&ipt_log_reg))
return -EINVAL;
if (nflog)
nf_log_register(PF_INET, &ipt_logfn);
return 0;
}
static void __exit fini(void)
{
if (nflog)
nf_log_unregister(PF_INET, &ipt_logfn);
ipt_unregister_target(&ipt_log_reg);
}
module_init(init);
module_exit(fini);