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