net/netfilter/nft_log.c

   1 /*
   2  * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
   3  * Copyright (c) 2012-2014 Pablo Neira Ayuso <pablo@netfilter.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Development of this code funded by Astaro AG (http://www.astaro.com/)
  10  */
  11
  12 #include <linux/audit.h>
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/netlink.h>
  17 #include <linux/netfilter.h>
  18 #include <linux/netfilter/nf_tables.h>
  19 #include <net/ipv6.h>
  20 #include <net/ip.h>
  21 #include <net/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_log.h>
  23 #include <linux/netdevice.h>
  24
  25 static const char *nft_log_null_prefix = "";
  26
  27 struct nft_log {
  28         struct nf_loginfo       loginfo;
  29         char                    *prefix;
  30 };
  31
  32 static bool audit_ip4(struct audit_buffer *ab, struct sk_buff *skb)
  33 {
  34         struct iphdr _iph;
  35         const struct iphdr *ih;
  36
  37         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_iph), &_iph);
  38         if (!ih)
  39                 return false;
  40
  41         audit_log_format(ab, " saddr=%pI4 daddr=%pI4 proto=%hhu",
  42                          &ih->saddr, &ih->daddr, ih->protocol);
  43
  44         return true;
  45 }
  46
  47 static bool audit_ip6(struct audit_buffer *ab, struct sk_buff *skb)
  48 {
  49         struct ipv6hdr _ip6h;
  50         const struct ipv6hdr *ih;
  51         u8 nexthdr;
  52         __be16 frag_off;
  53
  54         ih = skb_header_pointer(skb, skb_network_offset(skb), sizeof(_ip6h), &_ip6h);
  55         if (!ih)
  56                 return false;
  57
  58         nexthdr = ih->nexthdr;
  59         ipv6_skip_exthdr(skb, skb_network_offset(skb) + sizeof(_ip6h), &nexthdr, &frag_off);
  60
  61         audit_log_format(ab, " saddr=%pI6c daddr=%pI6c proto=%hhu",
  62                          &ih->saddr, &ih->daddr, nexthdr);
  63
  64         return true;
  65 }
  66
  67 static void nft_log_eval_audit(const struct nft_pktinfo *pkt)
  68 {
  69         struct sk_buff *skb = pkt->skb;
  70         struct audit_buffer *ab;
  71         int fam = -1;
  72
  73         if (!audit_enabled)
  74                 return;
  75
  76         ab = audit_log_start(NULL, GFP_ATOMIC, AUDIT_NETFILTER_PKT);
  77         if (!ab)
  78                 return;
  79
  80         audit_log_format(ab, "mark=%#x", skb->mark);
  81
  82         switch (nft_pf(pkt)) {
  83         case NFPROTO_BRIDGE:
  84                 switch (eth_hdr(skb)->h_proto) {
  85                 case htons(ETH_P_IP):
  86                         fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  87                         break;
  88                 case htons(ETH_P_IPV6):
  89                         fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  90                         break;
  91                 }
  92                 break;
  93         case NFPROTO_IPV4:
  94                 fam = audit_ip4(ab, skb) ? NFPROTO_IPV4 : -1;
  95                 break;
  96         case NFPROTO_IPV6:
  97                 fam = audit_ip6(ab, skb) ? NFPROTO_IPV6 : -1;
  98                 break;
  99         }
 100
 101         if (fam == -1)
 102                 audit_log_format(ab, " saddr=? daddr=? proto=-1");
 103
 104         audit_log_end(ab);
 105 }
 106
 107 static void nft_log_eval(const struct nft_expr *expr,
 108                          struct nft_regs *regs,
 109                          const struct nft_pktinfo *pkt)
 110 {
 111         const struct nft_log *priv = nft_expr_priv(expr);
 112
 113         if (priv->loginfo.type == NF_LOG_TYPE_LOG &&
 114             priv->loginfo.u.log.level == NFT_LOGLEVEL_AUDIT) {
 115                 nft_log_eval_audit(pkt);
 116                 return;
 117         }
 118
 119         nf_log_packet(nft_net(pkt), nft_pf(pkt), nft_hook(pkt), pkt->skb,
 120                       nft_in(pkt), nft_out(pkt), &priv->loginfo, "%s",
 121                       priv->prefix);
 122 }
 123
 124 static const struct nla_policy nft_log_policy[NFTA_LOG_MAX + 1] = {
 125         [NFTA_LOG_GROUP]        = { .type = NLA_U16 },
 126         [NFTA_LOG_PREFIX]       = { .type = NLA_STRING,
 127                                     .len = NF_LOG_PREFIXLEN - 1 },
 128         [NFTA_LOG_SNAPLEN]      = { .type = NLA_U32 },
 129         [NFTA_LOG_QTHRESHOLD]   = { .type = NLA_U16 },
 130         [NFTA_LOG_LEVEL]        = { .type = NLA_U32 },
 131         [NFTA_LOG_FLAGS]        = { .type = NLA_U32 },
 132 };
 133
 134 static int nft_log_init(const struct nft_ctx *ctx,
 135                         const struct nft_expr *expr,
 136                         const struct nlattr * const tb[])
 137 {
 138         struct nft_log *priv = nft_expr_priv(expr);
 139         struct nf_loginfo *li = &priv->loginfo;
 140         const struct nlattr *nla;
 141         int err;
 142
 143         li->type = NF_LOG_TYPE_LOG;
 144         if (tb[NFTA_LOG_LEVEL] != NULL &&
 145             tb[NFTA_LOG_GROUP] != NULL)
 146                 return -EINVAL;
 147         if (tb[NFTA_LOG_GROUP] != NULL) {
 148                 li->type = NF_LOG_TYPE_ULOG;
 149                 if (tb[NFTA_LOG_FLAGS] != NULL)
 150                         return -EINVAL;
 151         }
 152
 153         nla = tb[NFTA_LOG_PREFIX];
 154         if (nla != NULL) {
 155                 priv->prefix = kmalloc(nla_len(nla) + 1, GFP_KERNEL);
 156                 if (priv->prefix == NULL)
 157                         return -ENOMEM;
 158                 nla_strlcpy(priv->prefix, nla, nla_len(nla) + 1);
 159         } else {
 160                 priv->prefix = (char *)nft_log_null_prefix;
 161         }
 162
 163         switch (li->type) {
 164         case NF_LOG_TYPE_LOG:
 165                 if (tb[NFTA_LOG_LEVEL] != NULL) {
 166                         li->u.log.level =
 167                                 ntohl(nla_get_be32(tb[NFTA_LOG_LEVEL]));
 168                 } else {
 169                         li->u.log.level = NFT_LOGLEVEL_WARNING;
 170                 }
 171                 if (li->u.log.level > NFT_LOGLEVEL_AUDIT) {
 172                         err = -EINVAL;
 173                         goto err1;
 174                 }
 175
 176                 if (tb[NFTA_LOG_FLAGS] != NULL) {
 177                         li->u.log.logflags =
 178                                 ntohl(nla_get_be32(tb[NFTA_LOG_FLAGS]));
 179                         if (li->u.log.logflags & ~NF_LOG_MASK) {
 180                                 err = -EINVAL;
 181                                 goto err1;
 182                         }
 183                 }
 184                 break;
 185         case NF_LOG_TYPE_ULOG:
 186                 li->u.ulog.group = ntohs(nla_get_be16(tb[NFTA_LOG_GROUP]));
 187                 if (tb[NFTA_LOG_SNAPLEN] != NULL) {
 188                         li->u.ulog.flags |= NF_LOG_F_COPY_LEN;
 189                         li->u.ulog.copy_len =
 190                                 ntohl(nla_get_be32(tb[NFTA_LOG_SNAPLEN]));
 191                 }
 192                 if (tb[NFTA_LOG_QTHRESHOLD] != NULL) {
 193                         li->u.ulog.qthreshold =
 194                                 ntohs(nla_get_be16(tb[NFTA_LOG_QTHRESHOLD]));
 195                 }
 196                 break;
 197         }
 198
 199         if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
 200                 return 0;
 201
 202         err = nf_logger_find_get(ctx->family, li->type);
 203         if (err < 0)
 204                 goto err1;
 205
 206         return 0;
 207
 208 err1:
 209         if (priv->prefix != nft_log_null_prefix)
 210                 kfree(priv->prefix);
 211         return err;
 212 }
 213
 214 static void nft_log_destroy(const struct nft_ctx *ctx,
 215                             const struct nft_expr *expr)
 216 {
 217         struct nft_log *priv = nft_expr_priv(expr);
 218         struct nf_loginfo *li = &priv->loginfo;
 219
 220         if (priv->prefix != nft_log_null_prefix)
 221                 kfree(priv->prefix);
 222
 223         if (li->u.log.level == NFT_LOGLEVEL_AUDIT)
 224                 return;
 225
 226         nf_logger_put(ctx->family, li->type);
 227 }
 228
 229 static int nft_log_dump(struct sk_buff *skb, const struct nft_expr *expr)
 230 {
 231         const struct nft_log *priv = nft_expr_priv(expr);
 232         const struct nf_loginfo *li = &priv->loginfo;
 233
 234         if (priv->prefix != nft_log_null_prefix)
 235                 if (nla_put_string(skb, NFTA_LOG_PREFIX, priv->prefix))
 236                         goto nla_put_failure;
 237         switch (li->type) {
 238         case NF_LOG_TYPE_LOG:
 239                 if (nla_put_be32(skb, NFTA_LOG_LEVEL, htonl(li->u.log.level)))
 240                         goto nla_put_failure;
 241
 242                 if (li->u.log.logflags) {
 243                         if (nla_put_be32(skb, NFTA_LOG_FLAGS,
 244                                          htonl(li->u.log.logflags)))
 245                                 goto nla_put_failure;
 246                 }
 247                 break;
 248         case NF_LOG_TYPE_ULOG:
 249                 if (nla_put_be16(skb, NFTA_LOG_GROUP, htons(li->u.ulog.group)))
 250                         goto nla_put_failure;
 251
 252                 if (li->u.ulog.flags & NF_LOG_F_COPY_LEN) {
 253                         if (nla_put_be32(skb, NFTA_LOG_SNAPLEN,
 254                                          htonl(li->u.ulog.copy_len)))
 255                                 goto nla_put_failure;
 256                 }
 257                 if (li->u.ulog.qthreshold) {
 258                         if (nla_put_be16(skb, NFTA_LOG_QTHRESHOLD,
 259                                          htons(li->u.ulog.qthreshold)))
 260                                 goto nla_put_failure;
 261                 }
 262                 break;
 263         }
 264         return 0;
 265
 266 nla_put_failure:
 267         return -1;
 268 }
 269
 270 static struct nft_expr_type nft_log_type;
 271 static const struct nft_expr_ops nft_log_ops = {
 272         .type           = &nft_log_type,
 273         .size           = NFT_EXPR_SIZE(sizeof(struct nft_log)),
 274         .eval           = nft_log_eval,
 275         .init           = nft_log_init,
 276         .destroy        = nft_log_destroy,
 277         .dump           = nft_log_dump,
 278 };
 279
 280 static struct nft_expr_type nft_log_type __read_mostly = {
 281         .name           = "log",
 282         .ops            = &nft_log_ops,
 283         .policy         = nft_log_policy,
 284         .maxattr        = NFTA_LOG_MAX,
 285         .owner          = THIS_MODULE,
 286 };
 287
 288 static int __init nft_log_module_init(void)
 289 {
 290         return nft_register_expr(&nft_log_type);
 291 }
 292
 293 static void __exit nft_log_module_exit(void)
 294 {
 295         nft_unregister_expr(&nft_log_type);
 296 }
 297
 298 module_init(nft_log_module_init);
 299 module_exit(nft_log_module_exit);
 300
 301 MODULE_LICENSE("GPL");
 302 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 303 MODULE_ALIAS_NFT_EXPR("log");