linux/net/netfilter/nft_compat.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
   4 *
   5 * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
   6 */
   7
   8#include <linux/kernel.h>
   9#include <linux/init.h>
  10#include <linux/module.h>
  11#include <linux/netlink.h>
  12#include <linux/netfilter.h>
  13#include <linux/netfilter/nfnetlink.h>
  14#include <linux/netfilter/nf_tables.h>
  15#include <linux/netfilter/nf_tables_compat.h>
  16#include <linux/netfilter/x_tables.h>
  17#include <linux/netfilter_ipv4/ip_tables.h>
  18#include <linux/netfilter_ipv6/ip6_tables.h>
  19#include <linux/netfilter_bridge/ebtables.h>
  20#include <linux/netfilter_arp/arp_tables.h>
  21#include <net/netfilter/nf_tables.h>
  22#include <net/netfilter/nf_log.h>
  23
  24/* Used for matches where *info is larger than X byte */
  25#define NFT_MATCH_LARGE_THRESH  192
  26
  27struct nft_xt_match_priv {
  28        void *info;
  29};
  30
  31static int nft_compat_chain_validate_dependency(const struct nft_ctx *ctx,
  32                                                const char *tablename)
  33{
  34        enum nft_chain_types type = NFT_CHAIN_T_DEFAULT;
  35        const struct nft_chain *chain = ctx->chain;
  36        const struct nft_base_chain *basechain;
  37
  38        if (!tablename ||
  39            !nft_is_base_chain(chain))
  40                return 0;
  41
  42        basechain = nft_base_chain(chain);
  43        if (strcmp(tablename, "nat") == 0) {
  44                if (ctx->family != NFPROTO_BRIDGE)
  45                        type = NFT_CHAIN_T_NAT;
  46                if (basechain->type->type != type)
  47                        return -EINVAL;
  48        }
  49
  50        return 0;
  51}
  52
  53union nft_entry {
  54        struct ipt_entry e4;
  55        struct ip6t_entry e6;
  56        struct ebt_entry ebt;
  57        struct arpt_entry arp;
  58};
  59
  60static inline void
  61nft_compat_set_par(struct xt_action_param *par,
  62                   const struct nft_pktinfo *pkt,
  63                   const void *xt, const void *xt_info)
  64{
  65        par->state      = pkt->state;
  66        par->thoff      = nft_thoff(pkt);
  67        par->fragoff    = pkt->fragoff;
  68        par->target     = xt;
  69        par->targinfo   = xt_info;
  70        par->hotdrop    = false;
  71}
  72
  73static void nft_target_eval_xt(const struct nft_expr *expr,
  74                               struct nft_regs *regs,
  75                               const struct nft_pktinfo *pkt)
  76{
  77        void *info = nft_expr_priv(expr);
  78        struct xt_target *target = expr->ops->data;
  79        struct sk_buff *skb = pkt->skb;
  80        struct xt_action_param xt;
  81        int ret;
  82
  83        nft_compat_set_par(&xt, pkt, target, info);
  84
  85        ret = target->target(skb, &xt);
  86
  87        if (xt.hotdrop)
  88                ret = NF_DROP;
  89
  90        switch (ret) {
  91        case XT_CONTINUE:
  92                regs->verdict.code = NFT_CONTINUE;
  93                break;
  94        default:
  95                regs->verdict.code = ret;
  96                break;
  97        }
  98}
  99
 100static void nft_target_eval_bridge(const struct nft_expr *expr,
 101                                   struct nft_regs *regs,
 102                                   const struct nft_pktinfo *pkt)
 103{
 104        void *info = nft_expr_priv(expr);
 105        struct xt_target *target = expr->ops->data;
 106        struct sk_buff *skb = pkt->skb;
 107        struct xt_action_param xt;
 108        int ret;
 109
 110        nft_compat_set_par(&xt, pkt, target, info);
 111
 112        ret = target->target(skb, &xt);
 113
 114        if (xt.hotdrop)
 115                ret = NF_DROP;
 116
 117        switch (ret) {
 118        case EBT_ACCEPT:
 119                regs->verdict.code = NF_ACCEPT;
 120                break;
 121        case EBT_DROP:
 122                regs->verdict.code = NF_DROP;
 123                break;
 124        case EBT_CONTINUE:
 125                regs->verdict.code = NFT_CONTINUE;
 126                break;
 127        case EBT_RETURN:
 128                regs->verdict.code = NFT_RETURN;
 129                break;
 130        default:
 131                regs->verdict.code = ret;
 132                break;
 133        }
 134}
 135
 136static const struct nla_policy nft_target_policy[NFTA_TARGET_MAX + 1] = {
 137        [NFTA_TARGET_NAME]      = { .type = NLA_NUL_STRING },
 138        [NFTA_TARGET_REV]       = { .type = NLA_U32 },
 139        [NFTA_TARGET_INFO]      = { .type = NLA_BINARY },
 140};
 141
 142static void
 143nft_target_set_tgchk_param(struct xt_tgchk_param *par,
 144                           const struct nft_ctx *ctx,
 145                           struct xt_target *target, void *info,
 146                           union nft_entry *entry, u16 proto, bool inv)
 147{
 148        par->net        = ctx->net;
 149        par->table      = ctx->table->name;
 150        switch (ctx->family) {
 151        case AF_INET:
 152                entry->e4.ip.proto = proto;
 153                entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
 154                break;
 155        case AF_INET6:
 156                if (proto)
 157                        entry->e6.ipv6.flags |= IP6T_F_PROTO;
 158
 159                entry->e6.ipv6.proto = proto;
 160                entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
 161                break;
 162        case NFPROTO_BRIDGE:
 163                entry->ebt.ethproto = (__force __be16)proto;
 164                entry->ebt.invflags = inv ? EBT_IPROTO : 0;
 165                break;
 166        case NFPROTO_ARP:
 167                break;
 168        }
 169        par->entryinfo  = entry;
 170        par->target     = target;
 171        par->targinfo   = info;
 172        if (nft_is_base_chain(ctx->chain)) {
 173                const struct nft_base_chain *basechain =
 174                                                nft_base_chain(ctx->chain);
 175                const struct nf_hook_ops *ops = &basechain->ops;
 176
 177                par->hook_mask = 1 << ops->hooknum;
 178        } else {
 179                par->hook_mask = 0;
 180        }
 181        par->family     = ctx->family;
 182        par->nft_compat = true;
 183}
 184
 185static void target_compat_from_user(struct xt_target *t, void *in, void *out)
 186{
 187        int pad;
 188
 189        memcpy(out, in, t->targetsize);
 190        pad = XT_ALIGN(t->targetsize) - t->targetsize;
 191        if (pad > 0)
 192                memset(out + t->targetsize, 0, pad);
 193}
 194
 195static const struct nla_policy nft_rule_compat_policy[NFTA_RULE_COMPAT_MAX + 1] = {
 196        [NFTA_RULE_COMPAT_PROTO]        = { .type = NLA_U32 },
 197        [NFTA_RULE_COMPAT_FLAGS]        = { .type = NLA_U32 },
 198};
 199
 200static int nft_parse_compat(const struct nlattr *attr, u16 *proto, bool *inv)
 201{
 202        struct nlattr *tb[NFTA_RULE_COMPAT_MAX+1];
 203        u32 flags;
 204        int err;
 205
 206        err = nla_parse_nested_deprecated(tb, NFTA_RULE_COMPAT_MAX, attr,
 207                                          nft_rule_compat_policy, NULL);
 208        if (err < 0)
 209                return err;
 210
 211        if (!tb[NFTA_RULE_COMPAT_PROTO] || !tb[NFTA_RULE_COMPAT_FLAGS])
 212                return -EINVAL;
 213
 214        flags = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_FLAGS]));
 215        if (flags & ~NFT_RULE_COMPAT_F_MASK)
 216                return -EINVAL;
 217        if (flags & NFT_RULE_COMPAT_F_INV)
 218                *inv = true;
 219
 220        *proto = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_PROTO]));
 221        return 0;
 222}
 223
 224static void nft_compat_wait_for_destructors(void)
 225{
 226        /* xtables matches or targets can have side effects, e.g.
 227         * creation/destruction of /proc files.
 228         * The xt ->destroy functions are run asynchronously from
 229         * work queue.  If we have pending invocations we thus
 230         * need to wait for those to finish.
 231         */
 232        nf_tables_trans_destroy_flush_work();
 233}
 234
 235static int
 236nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 237                const struct nlattr * const tb[])
 238{
 239        void *info = nft_expr_priv(expr);
 240        struct xt_target *target = expr->ops->data;
 241        struct xt_tgchk_param par;
 242        size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
 243        u16 proto = 0;
 244        bool inv = false;
 245        union nft_entry e = {};
 246        int ret;
 247
 248        target_compat_from_user(target, nla_data(tb[NFTA_TARGET_INFO]), info);
 249
 250        if (ctx->nla[NFTA_RULE_COMPAT]) {
 251                ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
 252                if (ret < 0)
 253                        return ret;
 254        }
 255
 256        nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
 257
 258        nft_compat_wait_for_destructors();
 259
 260        ret = xt_check_target(&par, size, proto, inv);
 261        if (ret < 0) {
 262                if (ret == -ENOENT) {
 263                        const char *modname = NULL;
 264
 265                        if (strcmp(target->name, "LOG") == 0)
 266                                modname = "nf_log_syslog";
 267                        else if (strcmp(target->name, "NFLOG") == 0)
 268                                modname = "nfnetlink_log";
 269
 270                        if (modname &&
 271                            nft_request_module(ctx->net, "%s", modname) == -EAGAIN)
 272                                return -EAGAIN;
 273                }
 274
 275                return ret;
 276        }
 277
 278        /* The standard target cannot be used */
 279        if (!target->target)
 280                return -EINVAL;
 281
 282        return 0;
 283}
 284
 285static void __nft_mt_tg_destroy(struct module *me, const struct nft_expr *expr)
 286{
 287        module_put(me);
 288        kfree(expr->ops);
 289}
 290
 291static void
 292nft_target_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 293{
 294        struct xt_target *target = expr->ops->data;
 295        void *info = nft_expr_priv(expr);
 296        struct module *me = target->me;
 297        struct xt_tgdtor_param par;
 298
 299        par.net = ctx->net;
 300        par.target = target;
 301        par.targinfo = info;
 302        par.family = ctx->family;
 303        if (par.target->destroy != NULL)
 304                par.target->destroy(&par);
 305
 306        __nft_mt_tg_destroy(me, expr);
 307}
 308
 309static int nft_extension_dump_info(struct sk_buff *skb, int attr,
 310                                   const void *info,
 311                                   unsigned int size, unsigned int user_size)
 312{
 313        unsigned int info_size, aligned_size = XT_ALIGN(size);
 314        struct nlattr *nla;
 315
 316        nla = nla_reserve(skb, attr, aligned_size);
 317        if (!nla)
 318                return -1;
 319
 320        info_size = user_size ? : size;
 321        memcpy(nla_data(nla), info, info_size);
 322        memset(nla_data(nla) + info_size, 0, aligned_size - info_size);
 323
 324        return 0;
 325}
 326
 327static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
 328{
 329        const struct xt_target *target = expr->ops->data;
 330        void *info = nft_expr_priv(expr);
 331
 332        if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||
 333            nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||
 334            nft_extension_dump_info(skb, NFTA_TARGET_INFO, info,
 335                                    target->targetsize, target->usersize))
 336                goto nla_put_failure;
 337
 338        return 0;
 339
 340nla_put_failure:
 341        return -1;
 342}
 343
 344static int nft_target_validate(const struct nft_ctx *ctx,
 345                               const struct nft_expr *expr,
 346                               const struct nft_data **data)
 347{
 348        struct xt_target *target = expr->ops->data;
 349        unsigned int hook_mask = 0;
 350        int ret;
 351
 352        if (nft_is_base_chain(ctx->chain)) {
 353                const struct nft_base_chain *basechain =
 354                                                nft_base_chain(ctx->chain);
 355                const struct nf_hook_ops *ops = &basechain->ops;
 356
 357                hook_mask = 1 << ops->hooknum;
 358                if (target->hooks && !(hook_mask & target->hooks))
 359                        return -EINVAL;
 360
 361                ret = nft_compat_chain_validate_dependency(ctx, target->table);
 362                if (ret < 0)
 363                        return ret;
 364        }
 365        return 0;
 366}
 367
 368static void __nft_match_eval(const struct nft_expr *expr,
 369                             struct nft_regs *regs,
 370                             const struct nft_pktinfo *pkt,
 371                             void *info)
 372{
 373        struct xt_match *match = expr->ops->data;
 374        struct sk_buff *skb = pkt->skb;
 375        struct xt_action_param xt;
 376        bool ret;
 377
 378        nft_compat_set_par(&xt, pkt, match, info);
 379
 380        ret = match->match(skb, &xt);
 381
 382        if (xt.hotdrop) {
 383                regs->verdict.code = NF_DROP;
 384                return;
 385        }
 386
 387        switch (ret ? 1 : 0) {
 388        case 1:
 389                regs->verdict.code = NFT_CONTINUE;
 390                break;
 391        case 0:
 392                regs->verdict.code = NFT_BREAK;
 393                break;
 394        }
 395}
 396
 397static void nft_match_large_eval(const struct nft_expr *expr,
 398                                 struct nft_regs *regs,
 399                                 const struct nft_pktinfo *pkt)
 400{
 401        struct nft_xt_match_priv *priv = nft_expr_priv(expr);
 402
 403        __nft_match_eval(expr, regs, pkt, priv->info);
 404}
 405
 406static void nft_match_eval(const struct nft_expr *expr,
 407                           struct nft_regs *regs,
 408                           const struct nft_pktinfo *pkt)
 409{
 410        __nft_match_eval(expr, regs, pkt, nft_expr_priv(expr));
 411}
 412
 413static const struct nla_policy nft_match_policy[NFTA_MATCH_MAX + 1] = {
 414        [NFTA_MATCH_NAME]       = { .type = NLA_NUL_STRING },
 415        [NFTA_MATCH_REV]        = { .type = NLA_U32 },
 416        [NFTA_MATCH_INFO]       = { .type = NLA_BINARY },
 417};
 418
 419/* struct xt_mtchk_param and xt_tgchk_param look very similar */
 420static void
 421nft_match_set_mtchk_param(struct xt_mtchk_param *par, const struct nft_ctx *ctx,
 422                          struct xt_match *match, void *info,
 423                          union nft_entry *entry, u16 proto, bool inv)
 424{
 425        par->net        = ctx->net;
 426        par->table      = ctx->table->name;
 427        switch (ctx->family) {
 428        case AF_INET:
 429                entry->e4.ip.proto = proto;
 430                entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
 431                break;
 432        case AF_INET6:
 433                if (proto)
 434                        entry->e6.ipv6.flags |= IP6T_F_PROTO;
 435
 436                entry->e6.ipv6.proto = proto;
 437                entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
 438                break;
 439        case NFPROTO_BRIDGE:
 440                entry->ebt.ethproto = (__force __be16)proto;
 441                entry->ebt.invflags = inv ? EBT_IPROTO : 0;
 442                break;
 443        case NFPROTO_ARP:
 444                break;
 445        }
 446        par->entryinfo  = entry;
 447        par->match      = match;
 448        par->matchinfo  = info;
 449        if (nft_is_base_chain(ctx->chain)) {
 450                const struct nft_base_chain *basechain =
 451                                                nft_base_chain(ctx->chain);
 452                const struct nf_hook_ops *ops = &basechain->ops;
 453
 454                par->hook_mask = 1 << ops->hooknum;
 455        } else {
 456                par->hook_mask = 0;
 457        }
 458        par->family     = ctx->family;
 459        par->nft_compat = true;
 460}
 461
 462static void match_compat_from_user(struct xt_match *m, void *in, void *out)
 463{
 464        int pad;
 465
 466        memcpy(out, in, m->matchsize);
 467        pad = XT_ALIGN(m->matchsize) - m->matchsize;
 468        if (pad > 0)
 469                memset(out + m->matchsize, 0, pad);
 470}
 471
 472static int
 473__nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 474                 const struct nlattr * const tb[],
 475                 void *info)
 476{
 477        struct xt_match *match = expr->ops->data;
 478        struct xt_mtchk_param par;
 479        size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO]));
 480        u16 proto = 0;
 481        bool inv = false;
 482        union nft_entry e = {};
 483        int ret;
 484
 485        match_compat_from_user(match, nla_data(tb[NFTA_MATCH_INFO]), info);
 486
 487        if (ctx->nla[NFTA_RULE_COMPAT]) {
 488                ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
 489                if (ret < 0)
 490                        return ret;
 491        }
 492
 493        nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
 494
 495        nft_compat_wait_for_destructors();
 496
 497        return xt_check_match(&par, size, proto, inv);
 498}
 499
 500static int
 501nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 502               const struct nlattr * const tb[])
 503{
 504        return __nft_match_init(ctx, expr, tb, nft_expr_priv(expr));
 505}
 506
 507static int
 508nft_match_large_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
 509                     const struct nlattr * const tb[])
 510{
 511        struct nft_xt_match_priv *priv = nft_expr_priv(expr);
 512        struct xt_match *m = expr->ops->data;
 513        int ret;
 514
 515        priv->info = kmalloc(XT_ALIGN(m->matchsize), GFP_KERNEL);
 516        if (!priv->info)
 517                return -ENOMEM;
 518
 519        ret = __nft_match_init(ctx, expr, tb, priv->info);
 520        if (ret)
 521                kfree(priv->info);
 522        return ret;
 523}
 524
 525static void
 526__nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr,
 527                    void *info)
 528{
 529        struct xt_match *match = expr->ops->data;
 530        struct module *me = match->me;
 531        struct xt_mtdtor_param par;
 532
 533        par.net = ctx->net;
 534        par.match = match;
 535        par.matchinfo = info;
 536        par.family = ctx->family;
 537        if (par.match->destroy != NULL)
 538                par.match->destroy(&par);
 539
 540        __nft_mt_tg_destroy(me, expr);
 541}
 542
 543static void
 544nft_match_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 545{
 546        __nft_match_destroy(ctx, expr, nft_expr_priv(expr));
 547}
 548
 549static void
 550nft_match_large_destroy(const struct nft_ctx *ctx, const struct nft_expr *expr)
 551{
 552        struct nft_xt_match_priv *priv = nft_expr_priv(expr);
 553
 554        __nft_match_destroy(ctx, expr, priv->info);
 555        kfree(priv->info);
 556}
 557
 558static int __nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr,
 559                            void *info)
 560{
 561        struct xt_match *match = expr->ops->data;
 562
 563        if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||
 564            nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||
 565            nft_extension_dump_info(skb, NFTA_MATCH_INFO, info,
 566                                    match->matchsize, match->usersize))
 567                goto nla_put_failure;
 568
 569        return 0;
 570
 571nla_put_failure:
 572        return -1;
 573}
 574
 575static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr)
 576{
 577        return __nft_match_dump(skb, expr, nft_expr_priv(expr));
 578}
 579
 580static int nft_match_large_dump(struct sk_buff *skb, const struct nft_expr *e)
 581{
 582        struct nft_xt_match_priv *priv = nft_expr_priv(e);
 583
 584        return __nft_match_dump(skb, e, priv->info);
 585}
 586
 587static int nft_match_validate(const struct nft_ctx *ctx,
 588                              const struct nft_expr *expr,
 589                              const struct nft_data **data)
 590{
 591        struct xt_match *match = expr->ops->data;
 592        unsigned int hook_mask = 0;
 593        int ret;
 594
 595        if (nft_is_base_chain(ctx->chain)) {
 596                const struct nft_base_chain *basechain =
 597                                                nft_base_chain(ctx->chain);
 598                const struct nf_hook_ops *ops = &basechain->ops;
 599
 600                hook_mask = 1 << ops->hooknum;
 601                if (match->hooks && !(hook_mask & match->hooks))
 602                        return -EINVAL;
 603
 604                ret = nft_compat_chain_validate_dependency(ctx, match->table);
 605                if (ret < 0)
 606                        return ret;
 607        }
 608        return 0;
 609}
 610
 611static int
 612nfnl_compat_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 613                      int event, u16 family, const char *name,
 614                      int rev, int target)
 615{
 616        struct nlmsghdr *nlh;
 617        unsigned int flags = portid ? NLM_F_MULTI : 0;
 618
 619        event = nfnl_msg_type(NFNL_SUBSYS_NFT_COMPAT, event);
 620        nlh = nfnl_msg_put(skb, portid, seq, event, flags, family,
 621                           NFNETLINK_V0, 0);
 622        if (!nlh)
 623                goto nlmsg_failure;
 624
 625        if (nla_put_string(skb, NFTA_COMPAT_NAME, name) ||
 626            nla_put_be32(skb, NFTA_COMPAT_REV, htonl(rev)) ||
 627            nla_put_be32(skb, NFTA_COMPAT_TYPE, htonl(target)))
 628                goto nla_put_failure;
 629
 630        nlmsg_end(skb, nlh);
 631        return skb->len;
 632
 633nlmsg_failure:
 634nla_put_failure:
 635        nlmsg_cancel(skb, nlh);
 636        return -1;
 637}
 638
 639static int nfnl_compat_get_rcu(struct sk_buff *skb,
 640                               const struct nfnl_info *info,
 641                               const struct nlattr * const tb[])
 642{
 643        u8 family = info->nfmsg->nfgen_family;
 644        const char *name, *fmt;
 645        struct sk_buff *skb2;
 646        int ret = 0, target;
 647        u32 rev;
 648
 649        if (tb[NFTA_COMPAT_NAME] == NULL ||
 650            tb[NFTA_COMPAT_REV] == NULL ||
 651            tb[NFTA_COMPAT_TYPE] == NULL)
 652                return -EINVAL;
 653
 654        name = nla_data(tb[NFTA_COMPAT_NAME]);
 655        rev = ntohl(nla_get_be32(tb[NFTA_COMPAT_REV]));
 656        target = ntohl(nla_get_be32(tb[NFTA_COMPAT_TYPE]));
 657
 658        switch(family) {
 659        case AF_INET:
 660                fmt = "ipt_%s";
 661                break;
 662        case AF_INET6:
 663                fmt = "ip6t_%s";
 664                break;
 665        case NFPROTO_BRIDGE:
 666                fmt = "ebt_%s";
 667                break;
 668        case NFPROTO_ARP:
 669                fmt = "arpt_%s";
 670                break;
 671        default:
 672                pr_err("nft_compat: unsupported protocol %d\n", family);
 673                return -EINVAL;
 674        }
 675
 676        if (!try_module_get(THIS_MODULE))
 677                return -EINVAL;
 678
 679        rcu_read_unlock();
 680        try_then_request_module(xt_find_revision(family, name, rev, target, &ret),
 681                                fmt, name);
 682        if (ret < 0)
 683                goto out_put;
 684
 685        skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 686        if (skb2 == NULL) {
 687                ret = -ENOMEM;
 688                goto out_put;
 689        }
 690
 691        /* include the best revision for this extension in the message */
 692        if (nfnl_compat_fill_info(skb2, NETLINK_CB(skb).portid,
 693                                  info->nlh->nlmsg_seq,
 694                                  NFNL_MSG_TYPE(info->nlh->nlmsg_type),
 695                                  NFNL_MSG_COMPAT_GET,
 696                                  family, name, ret, target) <= 0) {
 697                kfree_skb(skb2);
 698                goto out_put;
 699        }
 700
 701        ret = nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 702out_put:
 703        rcu_read_lock();
 704        module_put(THIS_MODULE);
 705
 706        return ret;
 707}
 708
 709static const struct nla_policy nfnl_compat_policy_get[NFTA_COMPAT_MAX+1] = {
 710        [NFTA_COMPAT_NAME]      = { .type = NLA_NUL_STRING,
 711                                    .len = NFT_COMPAT_NAME_MAX-1 },
 712        [NFTA_COMPAT_REV]       = { .type = NLA_U32 },
 713        [NFTA_COMPAT_TYPE]      = { .type = NLA_U32 },
 714};
 715
 716static const struct nfnl_callback nfnl_nft_compat_cb[NFNL_MSG_COMPAT_MAX] = {
 717        [NFNL_MSG_COMPAT_GET]   = {
 718                .call           = nfnl_compat_get_rcu,
 719                .type           = NFNL_CB_RCU,
 720                .attr_count     = NFTA_COMPAT_MAX,
 721                .policy         = nfnl_compat_policy_get
 722        },
 723};
 724
 725static const struct nfnetlink_subsystem nfnl_compat_subsys = {
 726        .name           = "nft-compat",
 727        .subsys_id      = NFNL_SUBSYS_NFT_COMPAT,
 728        .cb_count       = NFNL_MSG_COMPAT_MAX,
 729        .cb             = nfnl_nft_compat_cb,
 730};
 731
 732static struct nft_expr_type nft_match_type;
 733
 734static const struct nft_expr_ops *
 735nft_match_select_ops(const struct nft_ctx *ctx,
 736                     const struct nlattr * const tb[])
 737{
 738        struct nft_expr_ops *ops;
 739        struct xt_match *match;
 740        unsigned int matchsize;
 741        char *mt_name;
 742        u32 rev, family;
 743        int err;
 744
 745        if (tb[NFTA_MATCH_NAME] == NULL ||
 746            tb[NFTA_MATCH_REV] == NULL ||
 747            tb[NFTA_MATCH_INFO] == NULL)
 748                return ERR_PTR(-EINVAL);
 749
 750        mt_name = nla_data(tb[NFTA_MATCH_NAME]);
 751        rev = ntohl(nla_get_be32(tb[NFTA_MATCH_REV]));
 752        family = ctx->family;
 753
 754        match = xt_request_find_match(family, mt_name, rev);
 755        if (IS_ERR(match))
 756                return ERR_PTR(-ENOENT);
 757
 758        if (match->matchsize > nla_len(tb[NFTA_MATCH_INFO])) {
 759                err = -EINVAL;
 760                goto err;
 761        }
 762
 763        ops = kzalloc(sizeof(struct nft_expr_ops), GFP_KERNEL);
 764        if (!ops) {
 765                err = -ENOMEM;
 766                goto err;
 767        }
 768
 769        ops->type = &nft_match_type;
 770        ops->eval = nft_match_eval;
 771        ops->init = nft_match_init;
 772        ops->destroy = nft_match_destroy;
 773        ops->dump = nft_match_dump;
 774        ops->validate = nft_match_validate;
 775        ops->data = match;
 776
 777        matchsize = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize));
 778        if (matchsize > NFT_MATCH_LARGE_THRESH) {
 779                matchsize = NFT_EXPR_SIZE(sizeof(struct nft_xt_match_priv));
 780
 781                ops->eval = nft_match_large_eval;
 782                ops->init = nft_match_large_init;
 783                ops->destroy = nft_match_large_destroy;
 784                ops->dump = nft_match_large_dump;
 785        }
 786
 787        ops->size = matchsize;
 788
 789        return ops;
 790err:
 791        module_put(match->me);
 792        return ERR_PTR(err);
 793}
 794
 795static void nft_match_release_ops(const struct nft_expr_ops *ops)
 796{
 797        struct xt_match *match = ops->data;
 798
 799        module_put(match->me);
 800        kfree(ops);
 801}
 802
 803static struct nft_expr_type nft_match_type __read_mostly = {
 804        .name           = "match",
 805        .select_ops     = nft_match_select_ops,
 806        .release_ops    = nft_match_release_ops,
 807        .policy         = nft_match_policy,
 808        .maxattr        = NFTA_MATCH_MAX,
 809        .owner          = THIS_MODULE,
 810};
 811
 812static struct nft_expr_type nft_target_type;
 813
 814static const struct nft_expr_ops *
 815nft_target_select_ops(const struct nft_ctx *ctx,
 816                      const struct nlattr * const tb[])
 817{
 818        struct nft_expr_ops *ops;
 819        struct xt_target *target;
 820        char *tg_name;
 821        u32 rev, family;
 822        int err;
 823
 824        if (tb[NFTA_TARGET_NAME] == NULL ||
 825            tb[NFTA_TARGET_REV] == NULL ||
 826            tb[NFTA_TARGET_INFO] == NULL)
 827                return ERR_PTR(-EINVAL);
 828
 829        tg_name = nla_data(tb[NFTA_TARGET_NAME]);
 830        rev = ntohl(nla_get_be32(tb[NFTA_TARGET_REV]));
 831        family = ctx->family;
 832
 833        if (strcmp(tg_name, XT_ERROR_TARGET) == 0 ||
 834            strcmp(tg_name, XT_STANDARD_TARGET) == 0 ||
 835            strcmp(tg_name, "standard") == 0)
 836                return ERR_PTR(-EINVAL);
 837
 838        target = xt_request_find_target(family, tg_name, rev);
 839        if (IS_ERR(target))
 840                return ERR_PTR(-ENOENT);
 841
 842        if (!target->target) {
 843                err = -EINVAL;
 844                goto err;
 845        }
 846
 847        if (target->targetsize > nla_len(tb[NFTA_TARGET_INFO])) {
 848                err = -EINVAL;
 849                goto err;
 850        }
 851
 852        ops = kzalloc(sizeof(struct nft_expr_ops), GFP_KERNEL);
 853        if (!ops) {
 854                err = -ENOMEM;
 855                goto err;
 856        }
 857
 858        ops->type = &nft_target_type;
 859        ops->size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize));
 860        ops->init = nft_target_init;
 861        ops->destroy = nft_target_destroy;
 862        ops->dump = nft_target_dump;
 863        ops->validate = nft_target_validate;
 864        ops->data = target;
 865
 866        if (family == NFPROTO_BRIDGE)
 867                ops->eval = nft_target_eval_bridge;
 868        else
 869                ops->eval = nft_target_eval_xt;
 870
 871        return ops;
 872err:
 873        module_put(target->me);
 874        return ERR_PTR(err);
 875}
 876
 877static void nft_target_release_ops(const struct nft_expr_ops *ops)
 878{
 879        struct xt_target *target = ops->data;
 880
 881        module_put(target->me);
 882        kfree(ops);
 883}
 884
 885static struct nft_expr_type nft_target_type __read_mostly = {
 886        .name           = "target",
 887        .select_ops     = nft_target_select_ops,
 888        .release_ops    = nft_target_release_ops,
 889        .policy         = nft_target_policy,
 890        .maxattr        = NFTA_TARGET_MAX,
 891        .owner          = THIS_MODULE,
 892};
 893
 894static int __init nft_compat_module_init(void)
 895{
 896        int ret;
 897
 898        ret = nft_register_expr(&nft_match_type);
 899        if (ret < 0)
 900                return ret;
 901
 902        ret = nft_register_expr(&nft_target_type);
 903        if (ret < 0)
 904                goto err_match;
 905
 906        ret = nfnetlink_subsys_register(&nfnl_compat_subsys);
 907        if (ret < 0) {
 908                pr_err("nft_compat: cannot register with nfnetlink.\n");
 909                goto err_target;
 910        }
 911
 912        return ret;
 913err_target:
 914        nft_unregister_expr(&nft_target_type);
 915err_match:
 916        nft_unregister_expr(&nft_match_type);
 917        return ret;
 918}
 919
 920static void __exit nft_compat_module_exit(void)
 921{
 922        nfnetlink_subsys_unregister(&nfnl_compat_subsys);
 923        nft_unregister_expr(&nft_target_type);
 924        nft_unregister_expr(&nft_match_type);
 925}
 926
 927MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
 928
 929module_init(nft_compat_module_init);
 930module_exit(nft_compat_module_exit);
 931
 932MODULE_LICENSE("GPL");
 933MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
 934MODULE_ALIAS_NFT_EXPR("match");
 935MODULE_ALIAS_NFT_EXPR("target");
 936MODULE_DESCRIPTION("x_tables over nftables support");
 937