linux/net/netfilter/nft_compat.c
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   1/*
   2 * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
   9 */
  10
  11#include <linux/kernel.h>
  12#include <linux/init.h>
  13#include <linux/module.h>
  14#include <linux/netlink.h>
  15#include <linux/netfilter.h>
  16#include <linux/netfilter/nfnetlink.h>
  17#include <linux/netfilter/nf_tables.h>
  18#include <linux/netfilter/nf_tables_compat.h>
  19#include <linux/netfilter/x_tables.h>
  20#include <linux/netfilter_ipv4/ip_tables.h>
  21#include <linux/netfilter_ipv6/ip6_tables.h>
  22#include <linux/netfilter_bridge/ebtables.h>
  23#include <linux/netfilter_arp/arp_tables.h>
  24#include <net/netfilter/nf_tables.h>
  25
  26struct nft_xt {
  27        struct list_head        head;
  28        struct nft_expr_ops     ops;
  29        unsigned int            refcnt;
  30};
  31
  32static void nft_xt_put(struct nft_xt *xt)
  33{
  34        if (--xt->refcnt == 0) {
  35                list_del(&xt->head);
  36                kfree(xt);
  37        }
  38}
  39
  40static int nft_compat_chain_validate_dependency(const char *tablename,
  41                                                const struct nft_chain *chain)
  42{
  43        const struct nft_base_chain *basechain;
  44
  45        if (!tablename ||
  46            !nft_is_base_chain(chain))
  47                return 0;
  48
  49        basechain = nft_base_chain(chain);
  50        if (strcmp(tablename, "nat") == 0 &&
  51            basechain->type->type != NFT_CHAIN_T_NAT)
  52                return -EINVAL;
  53
  54        return 0;
  55}
  56
  57union nft_entry {
  58        struct ipt_entry e4;
  59        struct ip6t_entry e6;
  60        struct ebt_entry ebt;
  61        struct arpt_entry arp;
  62};
  63
  64static inline void
  65nft_compat_set_par(struct xt_action_param *par, void *xt, const void *xt_info)
  66{
  67        par->target     = xt;
  68        par->targinfo   = xt_info;
  69        par->hotdrop    = false;
  70}
  71
  72static void nft_target_eval_xt(const struct nft_expr *expr,
  73                               struct nft_regs *regs,
  74                               const struct nft_pktinfo *pkt)
  75{
  76        void *info = nft_expr_priv(expr);
  77        struct xt_target *target = expr->ops->data;
  78        struct sk_buff *skb = pkt->skb;
  79        int ret;
  80
  81        nft_compat_set_par((struct xt_action_param *)&pkt->xt, target, info);
  82
  83        ret = target->target(skb, &pkt->xt);
  84
  85        if (pkt->xt.hotdrop)
  86                ret = NF_DROP;
  87
  88        switch (ret) {
  89        case XT_CONTINUE:
  90                regs->verdict.code = NFT_CONTINUE;
  91                break;
  92        default:
  93                regs->verdict.code = ret;
  94                break;
  95        }
  96}
  97
  98static void nft_target_eval_bridge(const struct nft_expr *expr,
  99                                   struct nft_regs *regs,
 100                                   const struct nft_pktinfo *pkt)
 101{
 102        void *info = nft_expr_priv(expr);
 103        struct xt_target *target = expr->ops->data;
 104        struct sk_buff *skb = pkt->skb;
 105        int ret;
 106
 107        nft_compat_set_par((struct xt_action_param *)&pkt->xt, target, info);
 108
 109        ret = target->target(skb, &pkt->xt);
 110
 111        if (pkt->xt.hotdrop)
 112                ret = NF_DROP;
 113
 114        switch (ret) {
 115        case EBT_ACCEPT:
 116                regs->verdict.code = NF_ACCEPT;
 117                break;
 118        case EBT_DROP:
 119                regs->verdict.code = NF_DROP;
 120                break;
 121        case EBT_CONTINUE:
 122                regs->verdict.code = NFT_CONTINUE;
 123                break;
 124        case EBT_RETURN:
 125                regs->verdict.code = NFT_RETURN;
 126                break;
 127        default:
 128                regs->verdict.code = ret;
 129                break;
 130        }
 131}
 132
 133static const struct nla_policy nft_target_policy[NFTA_TARGET_MAX + 1] = {
 134        [NFTA_TARGET_NAME]      = { .type = NLA_NUL_STRING },
 135        [NFTA_TARGET_REV]       = { .type = NLA_U32 },
 136        [NFTA_TARGET_INFO]      = { .type = NLA_BINARY },
 137};
 138
 139static void
 140nft_target_set_tgchk_param(struct xt_tgchk_param *par,
 141                           const struct nft_ctx *ctx,
 142                           struct xt_target *target, void *info,
 143                           union nft_entry *entry, u16 proto, bool inv)
 144{
 145        par->net        = ctx->net;
 146        par->table      = ctx->table->name;
 147        switch (ctx->family) {
 148        case AF_INET:
 149                entry->e4.ip.proto = proto;
 150                entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
 151                break;
 152        case AF_INET6:
 153                if (proto)
 154                        entry->e6.ipv6.flags |= IP6T_F_PROTO;
 155
 156                entry->e6.ipv6.proto = proto;
 157                entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
 158                break;
 159        case NFPROTO_BRIDGE:
 160                entry->ebt.ethproto = (__force __be16)proto;
 161                entry->ebt.invflags = inv ? EBT_IPROTO : 0;
 162                break;
 163        case NFPROTO_ARP:
 164                break;
 165        }
 166        par->entryinfo  = entry;
 167        par->target     = target;
 168        par->targinfo   = info;
 169        if (nft_is_base_chain(ctx->chain)) {
 170                const struct nft_base_chain *basechain =
 171                                                nft_base_chain(ctx->chain);
 172                const struct nf_hook_ops *ops = &basechain->ops;
 173
 174                par->hook_mask = 1 << ops->hooknum;
 175        } else {
 176                par->hook_mask = 0;
 177        }
 178        par->family     = ctx->family;
 179        par->nft_compat = true;
 180}
 181
 182static void target_compat_from_user(struct xt_target *t, void *in, void *out)
 183{
 184        int pad;
 185
 186        memcpy(out, in, t->targetsize);
 187        pad = XT_ALIGN(t->targetsize) - t->targetsize;
 188        if (pad > 0)
 189                memset(out + t->targetsize, 0, pad);
 190}
 191
 192static const struct nla_policy nft_rule_compat_policy[NFTA_RULE_COMPAT_MAX + 1] = {
 193        [NFTA_RULE_COMPAT_PROTO]        = { .type = NLA_U32 },
 194        [NFTA_RULE_COMPAT_FLAGS]        = { .type = NLA_U32 },
 195};
 196
 197static int nft_parse_compat(const struct nlattr *attr, u16 *proto, bool *inv)
 198{
 199        struct nlattr *tb[NFTA_RULE_COMPAT_MAX+1];
 200        u32 flags;
 201        int err;
 202
 203        err = nla_parse_nested(tb, NFTA_RULE_COMPAT_MAX, attr,
 204                               nft_rule_compat_policy, NULL);
 205        if (err < 0)
 206                return err;
 207
 208        if (!tb[NFTA_RULE_COMPAT_PROTO] || !tb[NFTA_RULE_COMPAT_FLAGS])
 209                return -EINVAL;
 210
 211        flags = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_FLAGS]));
 212        if (flags & ~NFT_RULE_COMPAT_F_MASK)
 213                return -EINVAL;
 214        if (flags & NFT_RULE_COMPAT_F_INV)
 215                *inv = true;
 216
 217        *proto = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_PROTO]));
 218        return 0;
 219}
 220
 221static int
 222nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 223                const struct nlattr * const tb[])
 224{
 225        void *info = nft_expr_priv(expr);
 226        struct xt_target *target = expr->ops->data;
 227        struct xt_tgchk_param par;
 228        size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
 229        u16 proto = 0;
 230        bool inv = false;
 231        union nft_entry e = {};
 232        int ret;
 233
 234        target_compat_from_user(target, nla_data(tb[NFTA_TARGET_INFO]), info);
 235
 236        if (ctx->nla[NFTA_RULE_COMPAT]) {
 237                ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
 238                if (ret < 0)
 239                        goto err;
 240        }
 241
 242        nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
 243
 244        ret = xt_check_target(&par, size, proto, inv);
 245        if (ret < 0)
 246                goto err;
 247
 248        /* The standard target cannot be used */
 249        if (target->target == NULL) {
 250                ret = -EINVAL;
 251                goto err;
 252        }
 253
 254        return 0;
 255err:
 256        module_put(target->me);
 257        return ret;
 258}
 259
 260static void
 261nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 262{
 263        struct xt_target *target = expr->ops->data;
 264        void *info = nft_expr_priv(expr);
 265        struct xt_tgdtor_param par;
 266
 267        par.net = ctx->net;
 268        par.target = target;
 269        par.targinfo = info;
 270        par.family = ctx->family;
 271        if (par.target->destroy != NULL)
 272                par.target->destroy(&par);
 273
 274        nft_xt_put(container_of(expr->ops, struct nft_xt, ops));
 275        module_put(target->me);
 276}
 277
 278static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
 279{
 280        const struct xt_target *target = expr->ops->data;
 281        void *info = nft_expr_priv(expr);
 282
 283        if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||
 284            nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||
 285            nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(target->targetsize), info))
 286                goto nla_put_failure;
 287
 288        return 0;
 289
 290nla_put_failure:
 291        return -1;
 292}
 293
 294static int nft_target_validate(const struct nft_ctx *ctx,
 295                               const struct nft_expr *expr,
 296                               const struct nft_data **data)
 297{
 298        struct xt_target *target = expr->ops->data;
 299        unsigned int hook_mask = 0;
 300        int ret;
 301
 302        if (nft_is_base_chain(ctx->chain)) {
 303                const struct nft_base_chain *basechain =
 304                                                nft_base_chain(ctx->chain);
 305                const struct nf_hook_ops *ops = &basechain->ops;
 306
 307                hook_mask = 1 << ops->hooknum;
 308                if (target->hooks && !(hook_mask & target->hooks))
 309                        return -EINVAL;
 310
 311                ret = nft_compat_chain_validate_dependency(target->table,
 312                                                           ctx->chain);
 313                if (ret < 0)
 314                        return ret;
 315        }
 316        return 0;
 317}
 318
 319static void nft_match_eval(const struct nft_expr *expr,
 320                           struct nft_regs *regs,
 321                           const struct nft_pktinfo *pkt)
 322{
 323        void *info = nft_expr_priv(expr);
 324        struct xt_match *match = expr->ops->data;
 325        struct sk_buff *skb = pkt->skb;
 326        bool ret;
 327
 328        nft_compat_set_par((struct xt_action_param *)&pkt->xt, match, info);
 329
 330        ret = match->match(skb, (struct xt_action_param *)&pkt->xt);
 331
 332        if (pkt->xt.hotdrop) {
 333                regs->verdict.code = NF_DROP;
 334                return;
 335        }
 336
 337        switch (ret ? 1 : 0) {
 338        case 1:
 339                regs->verdict.code = NFT_CONTINUE;
 340                break;
 341        case 0:
 342                regs->verdict.code = NFT_BREAK;
 343                break;
 344        }
 345}
 346
 347static const struct nla_policy nft_match_policy[NFTA_MATCH_MAX + 1] = {
 348        [NFTA_MATCH_NAME]       = { .type = NLA_NUL_STRING },
 349        [NFTA_MATCH_REV]        = { .type = NLA_U32 },
 350        [NFTA_MATCH_INFO]       = { .type = NLA_BINARY },
 351};
 352
 353/* struct xt_mtchk_param and xt_tgchk_param look very similar */
 354static void
 355nft_match_set_mtchk_param(struct xt_mtchk_param *par, const struct nft_ctx *ctx,
 356                          struct xt_match *match, void *info,
 357                          union nft_entry *entry, u16 proto, bool inv)
 358{
 359        par->net        = ctx->net;
 360        par->table      = ctx->table->name;
 361        switch (ctx->family) {
 362        case AF_INET:
 363                entry->e4.ip.proto = proto;
 364                entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
 365                break;
 366        case AF_INET6:
 367                if (proto)
 368                        entry->e6.ipv6.flags |= IP6T_F_PROTO;
 369
 370                entry->e6.ipv6.proto = proto;
 371                entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
 372                break;
 373        case NFPROTO_BRIDGE:
 374                entry->ebt.ethproto = (__force __be16)proto;
 375                entry->ebt.invflags = inv ? EBT_IPROTO : 0;
 376                break;
 377        case NFPROTO_ARP:
 378                break;
 379        }
 380        par->entryinfo  = entry;
 381        par->match      = match;
 382        par->matchinfo  = info;
 383        if (nft_is_base_chain(ctx->chain)) {
 384                const struct nft_base_chain *basechain =
 385                                                nft_base_chain(ctx->chain);
 386                const struct nf_hook_ops *ops = &basechain->ops;
 387
 388                par->hook_mask = 1 << ops->hooknum;
 389        } else {
 390                par->hook_mask = 0;
 391        }
 392        par->family     = ctx->family;
 393        par->nft_compat = true;
 394}
 395
 396static void match_compat_from_user(struct xt_match *m, void *in, void *out)
 397{
 398        int pad;
 399
 400        memcpy(out, in, m->matchsize);
 401        pad = XT_ALIGN(m->matchsize) - m->matchsize;
 402        if (pad > 0)
 403                memset(out + m->matchsize, 0, pad);
 404}
 405
 406static int
 407nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 408                const struct nlattr * const tb[])
 409{
 410        void *info = nft_expr_priv(expr);
 411        struct xt_match *match = expr->ops->data;
 412        struct xt_mtchk_param par;
 413        size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO]));
 414        u16 proto = 0;
 415        bool inv = false;
 416        union nft_entry e = {};
 417        int ret;
 418
 419        match_compat_from_user(match, nla_data(tb[NFTA_MATCH_INFO]), info);
 420
 421        if (ctx->nla[NFTA_RULE_COMPAT]) {
 422                ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
 423                if (ret < 0)
 424                        goto err;
 425        }
 426
 427        nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
 428
 429        ret = xt_check_match(&par, size, proto, inv);
 430        if (ret < 0)
 431                goto err;
 432
 433        return 0;
 434err:
 435        module_put(match->me);
 436        return ret;
 437}
 438
 439static void
 440nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 441{
 442        struct xt_match *match = expr->ops->data;
 443        void *info = nft_expr_priv(expr);
 444        struct xt_mtdtor_param par;
 445
 446        par.net = ctx->net;
 447        par.match = match;
 448        par.matchinfo = info;
 449        par.family = ctx->family;
 450        if (par.match->destroy != NULL)
 451                par.match->destroy(&par);
 452
 453        nft_xt_put(container_of(expr->ops, struct nft_xt, ops));
 454        module_put(match->me);
 455}
 456
 457static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr)
 458{
 459        void *info = nft_expr_priv(expr);
 460        struct xt_match *match = expr->ops->data;
 461
 462        if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||
 463            nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||
 464            nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(match->matchsize), info))
 465                goto nla_put_failure;
 466
 467        return 0;
 468
 469nla_put_failure:
 470        return -1;
 471}
 472
 473static int nft_match_validate(const struct nft_ctx *ctx,
 474                              const struct nft_expr *expr,
 475                              const struct nft_data **data)
 476{
 477        struct xt_match *match = expr->ops->data;
 478        unsigned int hook_mask = 0;
 479        int ret;
 480
 481        if (nft_is_base_chain(ctx->chain)) {
 482                const struct nft_base_chain *basechain =
 483                                                nft_base_chain(ctx->chain);
 484                const struct nf_hook_ops *ops = &basechain->ops;
 485
 486                hook_mask = 1 << ops->hooknum;
 487                if (match->hooks && !(hook_mask & match->hooks))
 488                        return -EINVAL;
 489
 490                ret = nft_compat_chain_validate_dependency(match->table,
 491                                                           ctx->chain);
 492                if (ret < 0)
 493                        return ret;
 494        }
 495        return 0;
 496}
 497
 498static int
 499nfnl_compat_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 500                      int event, u16 family, const char *name,
 501                      int rev, int target)
 502{
 503        struct nlmsghdr *nlh;
 504        struct nfgenmsg *nfmsg;
 505        unsigned int flags = portid ? NLM_F_MULTI : 0;
 506
 507        event = nfnl_msg_type(NFNL_SUBSYS_NFT_COMPAT, event);
 508        nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 509        if (nlh == NULL)
 510                goto nlmsg_failure;
 511
 512        nfmsg = nlmsg_data(nlh);
 513        nfmsg->nfgen_family = family;
 514        nfmsg->version = NFNETLINK_V0;
 515        nfmsg->res_id = 0;
 516
 517        if (nla_put_string(skb, NFTA_COMPAT_NAME, name) ||
 518            nla_put_be32(skb, NFTA_COMPAT_REV, htonl(rev)) ||
 519            nla_put_be32(skb, NFTA_COMPAT_TYPE, htonl(target)))
 520                goto nla_put_failure;
 521
 522        nlmsg_end(skb, nlh);
 523        return skb->len;
 524
 525nlmsg_failure:
 526nla_put_failure:
 527        nlmsg_cancel(skb, nlh);
 528        return -1;
 529}
 530
 531static int nfnl_compat_get(struct net *net, struct sock *nfnl,
 532                           struct sk_buff *skb, const struct nlmsghdr *nlh,
 533                           const struct nlattr * const tb[],
 534                           struct netlink_ext_ack *extack)
 535{
 536        int ret = 0, target;
 537        struct nfgenmsg *nfmsg;
 538        const char *fmt;
 539        const char *name;
 540        u32 rev;
 541        struct sk_buff *skb2;
 542
 543        if (tb[NFTA_COMPAT_NAME] == NULL ||
 544            tb[NFTA_COMPAT_REV] == NULL ||
 545            tb[NFTA_COMPAT_TYPE] == NULL)
 546                return -EINVAL;
 547
 548        name = nla_data(tb[NFTA_COMPAT_NAME]);
 549        rev = ntohl(nla_get_be32(tb[NFTA_COMPAT_REV]));
 550        target = ntohl(nla_get_be32(tb[NFTA_COMPAT_TYPE]));
 551
 552        nfmsg = nlmsg_data(nlh);
 553
 554        switch(nfmsg->nfgen_family) {
 555        case AF_INET:
 556                fmt = "ipt_%s";
 557                break;
 558        case AF_INET6:
 559                fmt = "ip6t_%s";
 560                break;
 561        case NFPROTO_BRIDGE:
 562                fmt = "ebt_%s";
 563                break;
 564        case NFPROTO_ARP:
 565                fmt = "arpt_%s";
 566                break;
 567        default:
 568                pr_err("nft_compat: unsupported protocol %d\n",
 569                        nfmsg->nfgen_family);
 570                return -EINVAL;
 571        }
 572
 573        try_then_request_module(xt_find_revision(nfmsg->nfgen_family, name,
 574                                                 rev, target, &ret),
 575                                                 fmt, name);
 576
 577        if (ret < 0)
 578                return ret;
 579
 580        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 581        if (skb2 == NULL)
 582                return -ENOMEM;
 583
 584        /* include the best revision for this extension in the message */
 585        if (nfnl_compat_fill_info(skb2, NETLINK_CB(skb).portid,
 586                                  nlh->nlmsg_seq,
 587                                  NFNL_MSG_TYPE(nlh->nlmsg_type),
 588                                  NFNL_MSG_COMPAT_GET,
 589                                  nfmsg->nfgen_family,
 590                                  name, ret, target) <= 0) {
 591                kfree_skb(skb2);
 592                return -ENOSPC;
 593        }
 594
 595        ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 596                                MSG_DONTWAIT);
 597        if (ret > 0)
 598                ret = 0;
 599
 600        return ret == -EAGAIN ? -ENOBUFS : ret;
 601}
 602
 603static const struct nla_policy nfnl_compat_policy_get[NFTA_COMPAT_MAX+1] = {
 604        [NFTA_COMPAT_NAME]      = { .type = NLA_NUL_STRING,
 605                                    .len = NFT_COMPAT_NAME_MAX-1 },
 606        [NFTA_COMPAT_REV]       = { .type = NLA_U32 },
 607        [NFTA_COMPAT_TYPE]      = { .type = NLA_U32 },
 608};
 609
 610static const struct nfnl_callback nfnl_nft_compat_cb[NFNL_MSG_COMPAT_MAX] = {
 611        [NFNL_MSG_COMPAT_GET]           = { .call = nfnl_compat_get,
 612                                            .attr_count = NFTA_COMPAT_MAX,
 613                                            .policy = nfnl_compat_policy_get },
 614};
 615
 616static const struct nfnetlink_subsystem nfnl_compat_subsys = {
 617        .name           = "nft-compat",
 618        .subsys_id      = NFNL_SUBSYS_NFT_COMPAT,
 619        .cb_count       = NFNL_MSG_COMPAT_MAX,
 620        .cb             = nfnl_nft_compat_cb,
 621};
 622
 623static LIST_HEAD(nft_match_list);
 624
 625static struct nft_expr_type nft_match_type;
 626
 627static bool nft_match_cmp(const struct xt_match *match,
 628                          const char *name, u32 rev, u32 family)
 629{
 630        return strcmp(match->name, name) == 0 && match->revision == rev &&
 631               (match->family == NFPROTO_UNSPEC || match->family == family);
 632}
 633
 634static const struct nft_expr_ops *
 635nft_match_select_ops(const struct nft_ctx *ctx,
 636                     const struct nlattr * const tb[])
 637{
 638        struct nft_xt *nft_match;
 639        struct xt_match *match;
 640        char *mt_name;
 641        u32 rev, family;
 642        int err;
 643
 644        if (tb[NFTA_MATCH_NAME] == NULL ||
 645            tb[NFTA_MATCH_REV] == NULL ||
 646            tb[NFTA_MATCH_INFO] == NULL)
 647                return ERR_PTR(-EINVAL);
 648
 649        mt_name = nla_data(tb[NFTA_MATCH_NAME]);
 650        rev = ntohl(nla_get_be32(tb[NFTA_MATCH_REV]));
 651        family = ctx->family;
 652
 653        /* Re-use the existing match if it's already loaded. */
 654        list_for_each_entry(nft_match, &nft_match_list, head) {
 655                struct xt_match *match = nft_match->ops.data;
 656
 657                if (nft_match_cmp(match, mt_name, rev, family)) {
 658                        if (!try_module_get(match->me))
 659                                return ERR_PTR(-ENOENT);
 660
 661                        nft_match->refcnt++;
 662                        return &nft_match->ops;
 663                }
 664        }
 665
 666        match = xt_request_find_match(family, mt_name, rev);
 667        if (IS_ERR(match))
 668                return ERR_PTR(-ENOENT);
 669
 670        if (match->matchsize > nla_len(tb[NFTA_MATCH_INFO])) {
 671                err = -EINVAL;
 672                goto err;
 673        }
 674
 675        /* This is the first time we use this match, allocate operations */
 676        nft_match = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
 677        if (nft_match == NULL) {
 678                err = -ENOMEM;
 679                goto err;
 680        }
 681
 682        nft_match->refcnt = 1;
 683        nft_match->ops.type = &nft_match_type;
 684        nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));
 685        nft_match->ops.eval = nft_match_eval;
 686        nft_match->ops.init = nft_match_init;
 687        nft_match->ops.destroy = nft_match_destroy;
 688        nft_match->ops.dump = nft_match_dump;
 689        nft_match->ops.validate = nft_match_validate;
 690        nft_match->ops.data = match;
 691
 692        list_add(&nft_match->head, &nft_match_list);
 693
 694        return &nft_match->ops;
 695err:
 696        module_put(match->me);
 697        return ERR_PTR(err);
 698}
 699
 700static struct nft_expr_type nft_match_type __read_mostly = {
 701        .name           = "match",
 702        .select_ops     = nft_match_select_ops,
 703        .policy         = nft_match_policy,
 704        .maxattr        = NFTA_MATCH_MAX,
 705        .owner          = THIS_MODULE,
 706};
 707
 708static LIST_HEAD(nft_target_list);
 709
 710static struct nft_expr_type nft_target_type;
 711
 712static bool nft_target_cmp(const struct xt_target *tg,
 713                           const char *name, u32 rev, u32 family)
 714{
 715        return strcmp(tg->name, name) == 0 && tg->revision == rev &&
 716               (tg->family == NFPROTO_UNSPEC || tg->family == family);
 717}
 718
 719static const struct nft_expr_ops *
 720nft_target_select_ops(const struct nft_ctx *ctx,
 721                      const struct nlattr * const tb[])
 722{
 723        struct nft_xt *nft_target;
 724        struct xt_target *target;
 725        char *tg_name;
 726        u32 rev, family;
 727        int err;
 728
 729        if (tb[NFTA_TARGET_NAME] == NULL ||
 730            tb[NFTA_TARGET_REV] == NULL ||
 731            tb[NFTA_TARGET_INFO] == NULL)
 732                return ERR_PTR(-EINVAL);
 733
 734        tg_name = nla_data(tb[NFTA_TARGET_NAME]);
 735        rev = ntohl(nla_get_be32(tb[NFTA_TARGET_REV]));
 736        family = ctx->family;
 737
 738        /* Re-use the existing target if it's already loaded. */
 739        list_for_each_entry(nft_target, &nft_target_list, head) {
 740                struct xt_target *target = nft_target->ops.data;
 741
 742                if (nft_target_cmp(target, tg_name, rev, family)) {
 743                        if (!try_module_get(target->me))
 744                                return ERR_PTR(-ENOENT);
 745
 746                        nft_target->refcnt++;
 747                        return &nft_target->ops;
 748                }
 749        }
 750
 751        target = xt_request_find_target(family, tg_name, rev);
 752        if (IS_ERR(target))
 753                return ERR_PTR(-ENOENT);
 754
 755        if (target->targetsize > nla_len(tb[NFTA_TARGET_INFO])) {
 756                err = -EINVAL;
 757                goto err;
 758        }
 759
 760        /* This is the first time we use this target, allocate operations */
 761        nft_target = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
 762        if (nft_target == NULL) {
 763                err = -ENOMEM;
 764                goto err;
 765        }
 766
 767        nft_target->refcnt = 1;
 768        nft_target->ops.type = &nft_target_type;
 769        nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
 770        nft_target->ops.init = nft_target_init;
 771        nft_target->ops.destroy = nft_target_destroy;
 772        nft_target->ops.dump = nft_target_dump;
 773        nft_target->ops.validate = nft_target_validate;
 774        nft_target->ops.data = target;
 775
 776        if (family == NFPROTO_BRIDGE)
 777                nft_target->ops.eval = nft_target_eval_bridge;
 778        else
 779                nft_target->ops.eval = nft_target_eval_xt;
 780
 781        list_add(&nft_target->head, &nft_target_list);
 782
 783        return &nft_target->ops;
 784err:
 785        module_put(target->me);
 786        return ERR_PTR(err);
 787}
 788
 789static struct nft_expr_type nft_target_type __read_mostly = {
 790        .name           = "target",
 791        .select_ops     = nft_target_select_ops,
 792        .policy         = nft_target_policy,
 793        .maxattr        = NFTA_TARGET_MAX,
 794        .owner          = THIS_MODULE,
 795};
 796
 797static int __init nft_compat_module_init(void)
 798{
 799        int ret;
 800
 801        ret = nft_register_expr(&nft_match_type);
 802        if (ret < 0)
 803                return ret;
 804
 805        ret = nft_register_expr(&nft_target_type);
 806        if (ret < 0)
 807                goto err_match;
 808
 809        ret = nfnetlink_subsys_register(&nfnl_compat_subsys);
 810        if (ret < 0) {
 811                pr_err("nft_compat: cannot register with nfnetlink.\n");
 812                goto err_target;
 813        }
 814
 815        return ret;
 816
 817err_target:
 818        nft_unregister_expr(&nft_target_type);
 819err_match:
 820        nft_unregister_expr(&nft_match_type);
 821        return ret;
 822}
 823
 824static void __exit nft_compat_module_exit(void)
 825{
 826        nfnetlink_subsys_unregister(&nfnl_compat_subsys);
 827        nft_unregister_expr(&nft_target_type);
 828        nft_unregister_expr(&nft_match_type);
 829}
 830
 831MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
 832
 833module_init(nft_compat_module_init);
 834module_exit(nft_compat_module_exit);
 835
 836MODULE_LICENSE("GPL");
 837MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 838MODULE_ALIAS_NFT_EXPR("match");
 839MODULE_ALIAS_NFT_EXPR("target");
 840