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linux-stable/net/ipv4/netfilter/nf_log_ipv4.c
Michal Kubeček 2851940ffe netfilter: allow logging from non-init namespaces 
Commit 69b34fb996 ("netfilter: xt_LOG: add net namespace support for
xt_LOG") disabled logging packets using the LOG target from non-init
namespaces. The motivation was to prevent containers from flooding
kernel log of the host. The plan was to keep it that way until syslog
namespace implementation allows containers to log in a safe way.

However, the work on syslog namespace seems to have hit a dead end
somewhere in 2013 and there are users who want to use xt_LOG in all
network namespaces. This patch allows to do so by setting

  /proc/sys/net/netfilter/nf_log_all_netns

to a nonzero value. This sysctl is only accessible from init_net so that
one cannot switch the behaviour from inside a container.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2017-02-02 14:31:58 +01:00

396 lines
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/* (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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/ip.h>
#include <net/ipv6.h>
#include <net/icmp.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/route.h>
#include <linux/netfilter.h>
#include <linux/netfilter/xt_LOG.h>
#include <net/netfilter/nf_log.h>
static struct nf_loginfo default_loginfo = {
.type = NF_LOG_TYPE_LOG,
.u = {
.log = {
.level = LOGLEVEL_NOTICE,
.logflags = NF_LOG_DEFAULT_MASK,
},
},
};
/* One level of recursion won't kill us */
static void dump_ipv4_packet(struct nf_log_buf *m,
const struct nf_loginfo *info,
const struct sk_buff *skb, unsigned int iphoff)
{
struct iphdr _iph;
const struct iphdr *ih;
unsigned int logflags;
if (info->type == NF_LOG_TYPE_LOG)
logflags = info->u.log.logflags;
else
logflags = NF_LOG_DEFAULT_MASK;
ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
if (ih == NULL) {
nf_log_buf_add(m, "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 " */
nf_log_buf_add(m, "SRC=%pI4 DST=%pI4 ", &ih->saddr, &ih->daddr);
/* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
nf_log_buf_add(m, "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)
nf_log_buf_add(m, "CE ");
if (ntohs(ih->frag_off) & IP_DF)
nf_log_buf_add(m, "DF ");
if (ntohs(ih->frag_off) & IP_MF)
nf_log_buf_add(m, "MF ");
/* Max length: 11 "FRAG:65535 " */
if (ntohs(ih->frag_off) & IP_OFFSET)
nf_log_buf_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
if ((logflags & NF_LOG_IPOPT) &&
ih->ihl * 4 > sizeof(struct iphdr)) {
const unsigned char *op;
unsigned char _opt[4 * 15 - sizeof(struct iphdr)];
unsigned int i, optsize;
optsize = ih->ihl * 4 - sizeof(struct iphdr);
op = skb_header_pointer(skb, iphoff+sizeof(_iph),
optsize, _opt);
if (op == NULL) {
nf_log_buf_add(m, "TRUNCATED");
return;
}
/* Max length: 127 "OPT (" 15*4*2chars ") " */
nf_log_buf_add(m, "OPT (");
for (i = 0; i < optsize; i++)
nf_log_buf_add(m, "%02X", op[i]);
nf_log_buf_add(m, ") ");
}
switch (ih->protocol) {
case IPPROTO_TCP:
if (nf_log_dump_tcp_header(m, skb, ih->protocol,
ntohs(ih->frag_off) & IP_OFFSET,
iphoff+ih->ihl*4, logflags))
return;
break;
case IPPROTO_UDP:
case IPPROTO_UDPLITE:
if (nf_log_dump_udp_header(m, skb, ih->protocol,
ntohs(ih->frag_off) & IP_OFFSET,
iphoff+ih->ihl*4))
return;
break;
case IPPROTO_ICMP: {
struct icmphdr _icmph;
const struct icmphdr *ich;
static const 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 " */
nf_log_buf_add(m, "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) {
nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Max length: 18 "TYPE=255 CODE=255 " */
nf_log_buf_add(m, "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]) {
nf_log_buf_add(m, "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 " */
nf_log_buf_add(m, "ID=%u SEQ=%u ",
ntohs(ich->un.echo.id),
ntohs(ich->un.echo.sequence));
break;
case ICMP_PARAMETERPROB:
/* Max length: 14 "PARAMETER=255 " */
nf_log_buf_add(m, "PARAMETER=%u ",
ntohl(ich->un.gateway) >> 24);
break;
case ICMP_REDIRECT:
/* Max length: 24 "GATEWAY=255.255.255.255 " */
nf_log_buf_add(m, "GATEWAY=%pI4 ", &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. */
nf_log_buf_add(m, "[");
dump_ipv4_packet(m, info, skb,
iphoff + ih->ihl*4+sizeof(_icmph));
nf_log_buf_add(m, "] ");
}
/* Max length: 10 "MTU=65535 " */
if (ich->type == ICMP_DEST_UNREACH &&
ich->code == ICMP_FRAG_NEEDED) {
nf_log_buf_add(m, "MTU=%u ",
ntohs(ich->un.frag.mtu));
}
}
break;
}
/* Max Length */
case IPPROTO_AH: {
struct ip_auth_hdr _ahdr;
const struct ip_auth_hdr *ah;
if (ntohs(ih->frag_off) & IP_OFFSET)
break;
/* Max length: 9 "PROTO=AH " */
nf_log_buf_add(m, "PROTO=AH ");
/* Max length: 25 "INCOMPLETE [65535 bytes] " */
ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
sizeof(_ahdr), &_ahdr);
if (ah == NULL) {
nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Length: 15 "SPI=0xF1234567 " */
nf_log_buf_add(m, "SPI=0x%x ", ntohl(ah->spi));
break;
}
case IPPROTO_ESP: {
struct ip_esp_hdr _esph;
const struct ip_esp_hdr *eh;
/* Max length: 10 "PROTO=ESP " */
nf_log_buf_add(m, "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) {
nf_log_buf_add(m, "INCOMPLETE [%u bytes] ",
skb->len - iphoff - ih->ihl*4);
break;
}
/* Length: 15 "SPI=0xF1234567 " */
nf_log_buf_add(m, "SPI=0x%x ", ntohl(eh->spi));
break;
}
/* Max length: 10 "PROTO 255 " */
default:
nf_log_buf_add(m, "PROTO=%u ", ih->protocol);
}
/* Max length: 15 "UID=4294967295 " */
if ((logflags & NF_LOG_UID) && !iphoff)
nf_log_dump_sk_uid_gid(m, skb->sk);
/* Max length: 16 "MARK=0xFFFFFFFF " */
if (!iphoff && skb->mark)
nf_log_buf_add(m, "MARK=0x%x ", skb->mark);
/* 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 */
/* UDPLITE: 14+max(25,20) = 39 */
/* 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 dump_ipv4_mac_header(struct nf_log_buf *m,
const struct nf_loginfo *info,
const struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
unsigned int logflags = 0;
if (info->type == NF_LOG_TYPE_LOG)
logflags = info->u.log.logflags;
if (!(logflags & NF_LOG_MACDECODE))
goto fallback;
switch (dev->type) {
case ARPHRD_ETHER:
nf_log_buf_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
ntohs(eth_hdr(skb)->h_proto));
return;
default:
break;
}
fallback:
nf_log_buf_add(m, "MAC=");
if (dev->hard_header_len &&
skb->mac_header != skb->network_header) {
const unsigned char *p = skb_mac_header(skb);
unsigned int i;
nf_log_buf_add(m, "%02x", *p++);
for (i = 1; i < dev->hard_header_len; i++, p++)
nf_log_buf_add(m, ":%02x", *p);
}
nf_log_buf_add(m, " ");
}
static void nf_log_ip_packet(struct net *net, u_int8_t pf,
unsigned int hooknum, const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct nf_loginfo *loginfo,
const char *prefix)
{
struct nf_log_buf *m;
/* FIXME: Disabled from containers until syslog ns is supported */
if (!net_eq(net, &init_net) && !sysctl_nf_log_all_netns)
return;
m = nf_log_buf_open();
if (!loginfo)
loginfo = &default_loginfo;
nf_log_dump_packet_common(m, pf, hooknum, skb, in,
out, loginfo, prefix);
if (in != NULL)
dump_ipv4_mac_header(m, loginfo, skb);
dump_ipv4_packet(m, loginfo, skb, 0);
nf_log_buf_close(m);
}
static struct nf_logger nf_ip_logger __read_mostly = {
.name = "nf_log_ipv4",
.type = NF_LOG_TYPE_LOG,
.logfn = nf_log_ip_packet,
.me = THIS_MODULE,
};
static int __net_init nf_log_ipv4_net_init(struct net *net)
{
return nf_log_set(net, NFPROTO_IPV4, &nf_ip_logger);
}
static void __net_exit nf_log_ipv4_net_exit(struct net *net)
{
nf_log_unset(net, &nf_ip_logger);
}
static struct pernet_operations nf_log_ipv4_net_ops = {
.init = nf_log_ipv4_net_init,
.exit = nf_log_ipv4_net_exit,
};
static int __init nf_log_ipv4_init(void)
{
int ret;
ret = register_pernet_subsys(&nf_log_ipv4_net_ops);
if (ret < 0)
return ret;
ret = nf_log_register(NFPROTO_IPV4, &nf_ip_logger);
if (ret < 0) {
pr_err("failed to register logger\n");
goto err1;
}
return 0;
err1:
unregister_pernet_subsys(&nf_log_ipv4_net_ops);
return ret;
}
static void __exit nf_log_ipv4_exit(void)
{
unregister_pernet_subsys(&nf_log_ipv4_net_ops);
nf_log_unregister(&nf_ip_logger);
}
module_init(nf_log_ipv4_init);
module_exit(nf_log_ipv4_exit);
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("Netfilter IPv4 packet logging");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NF_LOGGER(AF_INET, 0);
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