net/netfilter/xt_conntrack.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      xt_conntrack - Netfilter module to match connection tracking
   4  *      information. (Superset of Rusty's minimalistic state match.)
   5  *
   6  *      (C) 2001  Marc Boucher (marc@mbsi.ca).
   7  *      (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   8  *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
   9  */
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11 #include <linux/module.h>
  12 #include <linux/skbuff.h>
  13 #include <net/ipv6.h>
  14 #include <linux/netfilter/x_tables.h>
  15 #include <linux/netfilter/xt_conntrack.h>
  16 #include <net/netfilter/nf_conntrack.h>
  17
  18 MODULE_LICENSE("GPL");
  19 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
  20 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  21 MODULE_DESCRIPTION("Xtables: connection tracking state match");
  22 MODULE_ALIAS("ipt_conntrack");
  23 MODULE_ALIAS("ip6t_conntrack");
  24
  25 static bool
  26 conntrack_addrcmp(const union nf_inet_addr *kaddr,
  27                   const union nf_inet_addr *uaddr,
  28                   const union nf_inet_addr *umask, unsigned int l3proto)
  29 {
  30         if (l3proto == NFPROTO_IPV4)
  31                 return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
  32         else if (l3proto == NFPROTO_IPV6)
  33                 return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
  34                        &uaddr->in6) == 0;
  35         else
  36                 return false;
  37 }
  38
  39 static inline bool
  40 conntrack_mt_origsrc(const struct nf_conn *ct,
  41                      const struct xt_conntrack_mtinfo2 *info,
  42                      u_int8_t family)
  43 {
  44         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
  45                &info->origsrc_addr, &info->origsrc_mask, family);
  46 }
  47
  48 static inline bool
  49 conntrack_mt_origdst(const struct nf_conn *ct,
  50                      const struct xt_conntrack_mtinfo2 *info,
  51                      u_int8_t family)
  52 {
  53         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
  54                &info->origdst_addr, &info->origdst_mask, family);
  55 }
  56
  57 static inline bool
  58 conntrack_mt_replsrc(const struct nf_conn *ct,
  59                      const struct xt_conntrack_mtinfo2 *info,
  60                      u_int8_t family)
  61 {
  62         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
  63                &info->replsrc_addr, &info->replsrc_mask, family);
  64 }
  65
  66 static inline bool
  67 conntrack_mt_repldst(const struct nf_conn *ct,
  68                      const struct xt_conntrack_mtinfo2 *info,
  69                      u_int8_t family)
  70 {
  71         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
  72                &info->repldst_addr, &info->repldst_mask, family);
  73 }
  74
  75 static inline bool
  76 ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
  77                     const struct nf_conn *ct)
  78 {
  79         const struct nf_conntrack_tuple *tuple;
  80
  81         tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
  82         if ((info->match_flags & XT_CONNTRACK_PROTO) &&
  83             (nf_ct_protonum(ct) == info->l4proto) ^
  84             !(info->invert_flags & XT_CONNTRACK_PROTO))
  85                 return false;
  86
  87         /* Shortcut to match all recognized protocols by using ->src.all. */
  88         if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
  89             (tuple->src.u.all == info->origsrc_port) ^
  90             !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
  91                 return false;
  92
  93         if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
  94             (tuple->dst.u.all == info->origdst_port) ^
  95             !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
  96                 return false;
  97
  98         tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  99
 100         if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
 101             (tuple->src.u.all == info->replsrc_port) ^
 102             !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
 103                 return false;
 104
 105         if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
 106             (tuple->dst.u.all == info->repldst_port) ^
 107             !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
 108                 return false;
 109
 110         return true;
 111 }
 112
 113 static inline bool
 114 port_match(u16 min, u16 max, u16 port, bool invert)
 115 {
 116         return (port >= min && port <= max) ^ invert;
 117 }
 118
 119 static inline bool
 120 ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
 121                        const struct nf_conn *ct)
 122 {
 123         const struct nf_conntrack_tuple *tuple;
 124
 125         tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 126         if ((info->match_flags & XT_CONNTRACK_PROTO) &&
 127             (nf_ct_protonum(ct) == info->l4proto) ^
 128             !(info->invert_flags & XT_CONNTRACK_PROTO))
 129                 return false;
 130
 131         /* Shortcut to match all recognized protocols by using ->src.all. */
 132         if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
 133             !port_match(info->origsrc_port, info->origsrc_port_high,
 134                         ntohs(tuple->src.u.all),
 135                         info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
 136                 return false;
 137
 138         if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
 139             !port_match(info->origdst_port, info->origdst_port_high,
 140                         ntohs(tuple->dst.u.all),
 141                         info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
 142                 return false;
 143
 144         tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 145
 146         if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
 147             !port_match(info->replsrc_port, info->replsrc_port_high,
 148                         ntohs(tuple->src.u.all),
 149                         info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
 150                 return false;
 151
 152         if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
 153             !port_match(info->repldst_port, info->repldst_port_high,
 154                         ntohs(tuple->dst.u.all),
 155                         info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
 156                 return false;
 157
 158         return true;
 159 }
 160
 161 static bool
 162 conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
 163              u16 state_mask, u16 status_mask)
 164 {
 165         const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
 166         enum ip_conntrack_info ctinfo;
 167         const struct nf_conn *ct;
 168         unsigned int statebit;
 169
 170         ct = nf_ct_get(skb, &ctinfo);
 171
 172         if (ct)
 173                 statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
 174         else if (ctinfo == IP_CT_UNTRACKED)
 175                 statebit = XT_CONNTRACK_STATE_UNTRACKED;
 176         else
 177                 statebit = XT_CONNTRACK_STATE_INVALID;
 178
 179         if (info->match_flags & XT_CONNTRACK_STATE) {
 180                 if (ct != NULL) {
 181                         if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
 182                                 statebit |= XT_CONNTRACK_STATE_SNAT;
 183                         if (test_bit(IPS_DST_NAT_BIT, &ct->status))
 184                                 statebit |= XT_CONNTRACK_STATE_DNAT;
 185                 }
 186                 if (!!(state_mask & statebit) ^
 187                     !(info->invert_flags & XT_CONNTRACK_STATE))
 188                         return false;
 189         }
 190
 191         if (ct == NULL)
 192                 return info->match_flags & XT_CONNTRACK_STATE;
 193         if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
 194             (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
 195             !(info->invert_flags & XT_CONNTRACK_DIRECTION))
 196                 return false;
 197
 198         if (info->match_flags & XT_CONNTRACK_ORIGSRC)
 199                 if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
 200                     !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
 201                         return false;
 202
 203         if (info->match_flags & XT_CONNTRACK_ORIGDST)
 204                 if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
 205                     !(info->invert_flags & XT_CONNTRACK_ORIGDST))
 206                         return false;
 207
 208         if (info->match_flags & XT_CONNTRACK_REPLSRC)
 209                 if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
 210                     !(info->invert_flags & XT_CONNTRACK_REPLSRC))
 211                         return false;
 212
 213         if (info->match_flags & XT_CONNTRACK_REPLDST)
 214                 if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
 215                     !(info->invert_flags & XT_CONNTRACK_REPLDST))
 216                         return false;
 217
 218         if (par->match->revision != 3) {
 219                 if (!ct_proto_port_check(info, ct))
 220                         return false;
 221         } else {
 222                 if (!ct_proto_port_check_v3(par->matchinfo, ct))
 223                         return false;
 224         }
 225
 226         if ((info->match_flags & XT_CONNTRACK_STATUS) &&
 227             (!!(status_mask & ct->status) ^
 228             !(info->invert_flags & XT_CONNTRACK_STATUS)))
 229                 return false;
 230
 231         if (info->match_flags & XT_CONNTRACK_EXPIRES) {
 232                 unsigned long expires = nf_ct_expires(ct) / HZ;
 233
 234                 if ((expires >= info->expires_min &&
 235                     expires <= info->expires_max) ^
 236                     !(info->invert_flags & XT_CONNTRACK_EXPIRES))
 237                         return false;
 238         }
 239         return true;
 240 }
 241
 242 static bool
 243 conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 244 {
 245         const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
 246
 247         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 248 }
 249
 250 static bool
 251 conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 252 {
 253         const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
 254
 255         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 256 }
 257
 258 static bool
 259 conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
 260 {
 261         const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
 262
 263         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 264 }
 265
 266 static int conntrack_mt_check(const struct xt_mtchk_param *par)
 267 {
 268         int ret;
 269
 270         ret = nf_ct_netns_get(par->net, par->family);
 271         if (ret < 0)
 272                 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
 273                                     par->family);
 274         return ret;
 275 }
 276
 277 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
 278 {
 279         nf_ct_netns_put(par->net, par->family);
 280 }
 281
 282 static struct xt_match conntrack_mt_reg[] __read_mostly = {
 283         {
 284                 .name       = "conntrack",
 285                 .revision   = 1,
 286                 .family     = NFPROTO_UNSPEC,
 287                 .matchsize  = sizeof(struct xt_conntrack_mtinfo1),
 288                 .match      = conntrack_mt_v1,
 289                 .checkentry = conntrack_mt_check,
 290                 .destroy    = conntrack_mt_destroy,
 291                 .me         = THIS_MODULE,
 292         },
 293         {
 294                 .name       = "conntrack",
 295                 .revision   = 2,
 296                 .family     = NFPROTO_UNSPEC,
 297                 .matchsize  = sizeof(struct xt_conntrack_mtinfo2),
 298                 .match      = conntrack_mt_v2,
 299                 .checkentry = conntrack_mt_check,
 300                 .destroy    = conntrack_mt_destroy,
 301                 .me         = THIS_MODULE,
 302         },
 303         {
 304                 .name       = "conntrack",
 305                 .revision   = 3,
 306                 .family     = NFPROTO_UNSPEC,
 307                 .matchsize  = sizeof(struct xt_conntrack_mtinfo3),
 308                 .match      = conntrack_mt_v3,
 309                 .checkentry = conntrack_mt_check,
 310                 .destroy    = conntrack_mt_destroy,
 311                 .me         = THIS_MODULE,
 312         },
 313 };
 314
 315 static int __init conntrack_mt_init(void)
 316 {
 317         return xt_register_matches(conntrack_mt_reg,
 318                ARRAY_SIZE(conntrack_mt_reg));
 319 }
 320
 321 static void __exit conntrack_mt_exit(void)
 322 {
 323         xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
 324 }
 325
 326 module_init(conntrack_mt_init);
 327 module_exit(conntrack_mt_exit);