net/netfilter/xt_conntrack.c

   1 /*
   2  *      xt_conntrack - Netfilter module to match connection tracking
   3  *      information. (Superset of Rusty's minimalistic state match.)
   4  *
   5  *      (C) 2001  Marc Boucher (marc@mbsi.ca).
   6  *      (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   7  *      Copyright © CC Computer Consultants GmbH, 2007 - 2008
   8  *
   9  *      This program is free software; you can redistribute it and/or modify
  10  *      it under the terms of the GNU General Public License version 2 as
  11  *      published by the Free Software Foundation.
  12  */
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14 #include <linux/module.h>
  15 #include <linux/skbuff.h>
  16 #include <net/ipv6.h>
  17 #include <linux/netfilter/x_tables.h>
  18 #include <linux/netfilter/xt_conntrack.h>
  19 #include <net/netfilter/nf_conntrack.h>
  20
  21 MODULE_LICENSE("GPL");
  22 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
  23 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  24 MODULE_DESCRIPTION("Xtables: connection tracking state match");
  25 MODULE_ALIAS("ipt_conntrack");
  26 MODULE_ALIAS("ip6t_conntrack");
  27
  28 static bool
  29 conntrack_addrcmp(const union nf_inet_addr *kaddr,
  30                   const union nf_inet_addr *uaddr,
  31                   const union nf_inet_addr *umask, unsigned int l3proto)
  32 {
  33         if (l3proto == NFPROTO_IPV4)
  34                 return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
  35         else if (l3proto == NFPROTO_IPV6)
  36                 return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
  37                        &uaddr->in6) == 0;
  38         else
  39                 return false;
  40 }
  41
  42 static inline bool
  43 conntrack_mt_origsrc(const struct nf_conn *ct,
  44                      const struct xt_conntrack_mtinfo2 *info,
  45                      u_int8_t family)
  46 {
  47         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
  48                &info->origsrc_addr, &info->origsrc_mask, family);
  49 }
  50
  51 static inline bool
  52 conntrack_mt_origdst(const struct nf_conn *ct,
  53                      const struct xt_conntrack_mtinfo2 *info,
  54                      u_int8_t family)
  55 {
  56         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
  57                &info->origdst_addr, &info->origdst_mask, family);
  58 }
  59
  60 static inline bool
  61 conntrack_mt_replsrc(const struct nf_conn *ct,
  62                      const struct xt_conntrack_mtinfo2 *info,
  63                      u_int8_t family)
  64 {
  65         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
  66                &info->replsrc_addr, &info->replsrc_mask, family);
  67 }
  68
  69 static inline bool
  70 conntrack_mt_repldst(const struct nf_conn *ct,
  71                      const struct xt_conntrack_mtinfo2 *info,
  72                      u_int8_t family)
  73 {
  74         return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
  75                &info->repldst_addr, &info->repldst_mask, family);
  76 }
  77
  78 static inline bool
  79 ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
  80                     const struct nf_conn *ct)
  81 {
  82         const struct nf_conntrack_tuple *tuple;
  83
  84         tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
  85         if ((info->match_flags & XT_CONNTRACK_PROTO) &&
  86             (nf_ct_protonum(ct) == info->l4proto) ^
  87             !(info->invert_flags & XT_CONNTRACK_PROTO))
  88                 return false;
  89
  90         /* Shortcut to match all recognized protocols by using ->src.all. */
  91         if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
  92             (tuple->src.u.all == info->origsrc_port) ^
  93             !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
  94                 return false;
  95
  96         if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
  97             (tuple->dst.u.all == info->origdst_port) ^
  98             !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
  99                 return false;
 100
 101         tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 102
 103         if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
 104             (tuple->src.u.all == info->replsrc_port) ^
 105             !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
 106                 return false;
 107
 108         if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
 109             (tuple->dst.u.all == info->repldst_port) ^
 110             !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
 111                 return false;
 112
 113         return true;
 114 }
 115
 116 static inline bool
 117 port_match(u16 min, u16 max, u16 port, bool invert)
 118 {
 119         return (port >= min && port <= max) ^ invert;
 120 }
 121
 122 static inline bool
 123 ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
 124                        const struct nf_conn *ct)
 125 {
 126         const struct nf_conntrack_tuple *tuple;
 127
 128         tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
 129         if ((info->match_flags & XT_CONNTRACK_PROTO) &&
 130             (nf_ct_protonum(ct) == info->l4proto) ^
 131             !(info->invert_flags & XT_CONNTRACK_PROTO))
 132                 return false;
 133
 134         /* Shortcut to match all recognized protocols by using ->src.all. */
 135         if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
 136             !port_match(info->origsrc_port, info->origsrc_port_high,
 137                         ntohs(tuple->src.u.all),
 138                         info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
 139                 return false;
 140
 141         if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
 142             !port_match(info->origdst_port, info->origdst_port_high,
 143                         ntohs(tuple->dst.u.all),
 144                         info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
 145                 return false;
 146
 147         tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
 148
 149         if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
 150             !port_match(info->replsrc_port, info->replsrc_port_high,
 151                         ntohs(tuple->src.u.all),
 152                         info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
 153                 return false;
 154
 155         if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
 156             !port_match(info->repldst_port, info->repldst_port_high,
 157                         ntohs(tuple->dst.u.all),
 158                         info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
 159                 return false;
 160
 161         return true;
 162 }
 163
 164 static bool
 165 conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
 166              u16 state_mask, u16 status_mask)
 167 {
 168         const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
 169         enum ip_conntrack_info ctinfo;
 170         const struct nf_conn *ct;
 171         unsigned int statebit;
 172
 173         ct = nf_ct_get(skb, &ctinfo);
 174
 175         if (ct) {
 176                 if (nf_ct_is_untracked(ct))
 177                         statebit = XT_CONNTRACK_STATE_UNTRACKED;
 178                 else
 179                         statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
 180         } else
 181                 statebit = XT_CONNTRACK_STATE_INVALID;
 182
 183         if (info->match_flags & XT_CONNTRACK_STATE) {
 184                 if (ct != NULL) {
 185                         if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
 186                                 statebit |= XT_CONNTRACK_STATE_SNAT;
 187                         if (test_bit(IPS_DST_NAT_BIT, &ct->status))
 188                                 statebit |= XT_CONNTRACK_STATE_DNAT;
 189                 }
 190                 if (!!(state_mask & statebit) ^
 191                     !(info->invert_flags & XT_CONNTRACK_STATE))
 192                         return false;
 193         }
 194
 195         if (ct == NULL)
 196                 return info->match_flags & XT_CONNTRACK_STATE;
 197         if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
 198             (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
 199             !(info->invert_flags & XT_CONNTRACK_DIRECTION))
 200                 return false;
 201
 202         if (info->match_flags & XT_CONNTRACK_ORIGSRC)
 203                 if (conntrack_mt_origsrc(ct, info, par->family) ^
 204                     !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
 205                         return false;
 206
 207         if (info->match_flags & XT_CONNTRACK_ORIGDST)
 208                 if (conntrack_mt_origdst(ct, info, par->family) ^
 209                     !(info->invert_flags & XT_CONNTRACK_ORIGDST))
 210                         return false;
 211
 212         if (info->match_flags & XT_CONNTRACK_REPLSRC)
 213                 if (conntrack_mt_replsrc(ct, info, par->family) ^
 214                     !(info->invert_flags & XT_CONNTRACK_REPLSRC))
 215                         return false;
 216
 217         if (info->match_flags & XT_CONNTRACK_REPLDST)
 218                 if (conntrack_mt_repldst(ct, info, par->family) ^
 219                     !(info->invert_flags & XT_CONNTRACK_REPLDST))
 220                         return false;
 221
 222         if (par->match->revision != 3) {
 223                 if (!ct_proto_port_check(info, ct))
 224                         return false;
 225         } else {
 226                 if (!ct_proto_port_check_v3(par->matchinfo, ct))
 227                         return false;
 228         }
 229
 230         if ((info->match_flags & XT_CONNTRACK_STATUS) &&
 231             (!!(status_mask & ct->status) ^
 232             !(info->invert_flags & XT_CONNTRACK_STATUS)))
 233                 return false;
 234
 235         if (info->match_flags & XT_CONNTRACK_EXPIRES) {
 236                 unsigned long expires = 0;
 237
 238                 if (timer_pending(&ct->timeout))
 239                         expires = (ct->timeout.expires - jiffies) / HZ;
 240                 if ((expires >= info->expires_min &&
 241                     expires <= info->expires_max) ^
 242                     !(info->invert_flags & XT_CONNTRACK_EXPIRES))
 243                         return false;
 244         }
 245         return true;
 246 }
 247
 248 static bool
 249 conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
 250 {
 251         const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
 252
 253         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 254 }
 255
 256 static bool
 257 conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
 258 {
 259         const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
 260
 261         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 262 }
 263
 264 static bool
 265 conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
 266 {
 267         const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
 268
 269         return conntrack_mt(skb, par, info->state_mask, info->status_mask);
 270 }
 271
 272 static int conntrack_mt_check(const struct xt_mtchk_param *par)
 273 {
 274         int ret;
 275
 276         ret = nf_ct_l3proto_try_module_get(par->family);
 277         if (ret < 0)
 278                 pr_info("cannot load conntrack support for proto=%u\n",
 279                         par->family);
 280         return ret;
 281 }
 282
 283 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
 284 {
 285         nf_ct_l3proto_module_put(par->family);
 286 }
 287
 288 static struct xt_match conntrack_mt_reg[] __read_mostly = {
 289         {
 290                 .name       = "conntrack",
 291                 .revision   = 1,
 292                 .family     = NFPROTO_UNSPEC,
 293                 .matchsize  = sizeof(struct xt_conntrack_mtinfo1),
 294                 .match      = conntrack_mt_v1,
 295                 .checkentry = conntrack_mt_check,
 296                 .destroy    = conntrack_mt_destroy,
 297                 .me         = THIS_MODULE,
 298         },
 299         {
 300                 .name       = "conntrack",
 301                 .revision   = 2,
 302                 .family     = NFPROTO_UNSPEC,
 303                 .matchsize  = sizeof(struct xt_conntrack_mtinfo2),
 304                 .match      = conntrack_mt_v2,
 305                 .checkentry = conntrack_mt_check,
 306                 .destroy    = conntrack_mt_destroy,
 307                 .me         = THIS_MODULE,
 308         },
 309         {
 310                 .name       = "conntrack",
 311                 .revision   = 3,
 312                 .family     = NFPROTO_UNSPEC,
 313                 .matchsize  = sizeof(struct xt_conntrack_mtinfo3),
 314                 .match      = conntrack_mt_v3,
 315                 .checkentry = conntrack_mt_check,
 316                 .destroy    = conntrack_mt_destroy,
 317                 .me         = THIS_MODULE,
 318         },
 319 };
 320
 321 static int __init conntrack_mt_init(void)
 322 {
 323         return xt_register_matches(conntrack_mt_reg,
 324                ARRAY_SIZE(conntrack_mt_reg));
 325 }
 326
 327 static void __exit conntrack_mt_exit(void)
 328 {
 329         xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
 330 }
 331
 332 module_init(conntrack_mt_init);
 333 module_exit(conntrack_mt_exit);