net/netfilter/xt_LOG.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This is a module which is used for logging packets.
   4  */
   5
   6 /* (C) 1999-2001 Paul `Rusty' Russell
   7  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11 #include <linux/module.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/if_arp.h>
  15 #include <linux/ip.h>
  16 #include <net/ipv6.h>
  17 #include <net/icmp.h>
  18 #include <net/udp.h>
  19 #include <net/tcp.h>
  20 #include <net/route.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/x_tables.h>
  24 #include <linux/netfilter/xt_LOG.h>
  25 #include <linux/netfilter_ipv6/ip6_tables.h>
  26 #include <net/netfilter/nf_log.h>
  27
  28 static unsigned int
  29 log_tg(struct sk_buff *skb, const struct xt_action_param *par)
  30 {
  31         const struct xt_log_info *loginfo = par->targinfo;
  32         struct net *net = xt_net(par);
  33         struct nf_loginfo li;
  34
  35         li.type = NF_LOG_TYPE_LOG;
  36         li.u.log.level = loginfo->level;
  37         li.u.log.logflags = loginfo->logflags;
  38
  39         nf_log_packet(net, xt_family(par), xt_hooknum(par), skb, xt_in(par),
  40                       xt_out(par), &li, "%s", loginfo->prefix);
  41         return XT_CONTINUE;
  42 }
  43
  44 static int log_tg_check(const struct xt_tgchk_param *par)
  45 {
  46         const struct xt_log_info *loginfo = par->targinfo;
  47
  48         if (par->family != NFPROTO_IPV4 && par->family != NFPROTO_IPV6)
  49                 return -EINVAL;
  50
  51         if (loginfo->level >= 8) {
  52                 pr_debug("level %u >= 8\n", loginfo->level);
  53                 return -EINVAL;
  54         }
  55
  56         if (loginfo->prefix[sizeof(loginfo->prefix)-1] != '\0') {
  57                 pr_debug("prefix is not null-terminated\n");
  58                 return -EINVAL;
  59         }
  60
  61         return nf_logger_find_get(par->family, NF_LOG_TYPE_LOG);
  62 }
  63
  64 static void log_tg_destroy(const struct xt_tgdtor_param *par)
  65 {
  66         nf_logger_put(par->family, NF_LOG_TYPE_LOG);
  67 }
  68
  69 static struct xt_target log_tg_regs[] __read_mostly = {
  70         {
  71                 .name           = "LOG",
  72                 .family         = NFPROTO_IPV4,
  73                 .target         = log_tg,
  74                 .targetsize     = sizeof(struct xt_log_info),
  75                 .checkentry     = log_tg_check,
  76                 .destroy        = log_tg_destroy,
  77                 .me             = THIS_MODULE,
  78         },
  79 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  80         {
  81                 .name           = "LOG",
  82                 .family         = NFPROTO_IPV6,
  83                 .target         = log_tg,
  84                 .targetsize     = sizeof(struct xt_log_info),
  85                 .checkentry     = log_tg_check,
  86                 .destroy        = log_tg_destroy,
  87                 .me             = THIS_MODULE,
  88         },
  89 #endif
  90 };
  91
  92 static int __init log_tg_init(void)
  93 {
  94         return xt_register_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
  95 }
  96
  97 static void __exit log_tg_exit(void)
  98 {
  99         xt_unregister_targets(log_tg_regs, ARRAY_SIZE(log_tg_regs));
 100 }
 101
 102 module_init(log_tg_init);
 103 module_exit(log_tg_exit);
 104
 105 MODULE_LICENSE("GPL");
 106 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 107 MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
 108 MODULE_DESCRIPTION("Xtables: IPv4/IPv6 packet logging");
 109 MODULE_ALIAS("ipt_LOG");
 110 MODULE_ALIAS("ip6t_LOG");