linux/net/netfilter/xt_conntrack.c
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   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 \xC2\xA9 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
  18MODULE_LICENSE("GPL");
  19MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
  20MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
  21MODULE_DESCRIPTION("Xtables: connection tracking state match");
  22MODULE_ALIAS("ipt_conntrack");
  23MODULE_ALIAS("ip6t_conntrack");
  24
  25static bool
  26conntrack_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
  39static inline bool
  40conntrack_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
  48static inline bool
  49conntrack_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
  57static inline bool
  58conntrack_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
  66static inline bool
  67conntrack_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
  75static inline bool
  76ct_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
 113static inline bool
 114port_match(u16 min, u16 max, u16 port, bool invert)
 115{
 116        return (port >= min && port <= max) ^ invert;
 117}
 118
 119static inline bool
 120ct_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
 161static bool
 162conntrack_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
 242static bool
 243conntrack_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
 250static bool
 251conntrack_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
 258static bool
 259conntrack_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
 266static 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
 277static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
 278{
 279        nf_ct_netns_put(par->net, par->family);
 280}
 281
 282static 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
 315static int __init conntrack_mt_init(void)
 316{
 317        return xt_register_matches(conntrack_mt_reg,
 318               ARRAY_SIZE(conntrack_mt_reg));
 319}
 320
 321static void __exit conntrack_mt_exit(void)
 322{
 323        xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
 324}
 325
 326module_init(conntrack_mt_init);
 327module_exit(conntrack_mt_exit);
 328