net/netfilter/nf_tables_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   4  *
   5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/rculist.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/static_key.h>
  17 #include <linux/netfilter/nfnetlink.h>
  18 #include <linux/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_tables_core.h>
  20 #include <net/netfilter/nf_tables.h>
  21 #include <net/netfilter/nf_log.h>
  22 #include <net/netfilter/nft_meta.h>
  23
  24 #if defined(CONFIG_RETPOLINE) && defined(CONFIG_X86)
  25
  26 static struct static_key_false nf_tables_skip_direct_calls;
  27
  28 static bool nf_skip_indirect_calls(void)
  29 {
  30         return static_branch_likely(&nf_tables_skip_direct_calls);
  31 }
  32
  33 static void __init nf_skip_indirect_calls_enable(void)
  34 {
  35         if (!cpu_feature_enabled(X86_FEATURE_RETPOLINE))
  36                 static_branch_enable(&nf_tables_skip_direct_calls);
  37 }
  38 #else
  39 static inline bool nf_skip_indirect_calls(void) { return false; }
  40
  41 static inline void nf_skip_indirect_calls_enable(void) { }
  42 #endif
  43
  44 static noinline void __nft_trace_packet(const struct nft_pktinfo *pkt,
  45                                         const struct nft_verdict *verdict,
  46                                         const struct nft_rule_dp *rule,
  47                                         struct nft_traceinfo *info,
  48                                         enum nft_trace_types type)
  49 {
  50         if (!info->trace || !info->nf_trace)
  51                 return;
  52
  53         info->type = type;
  54
  55         nft_trace_notify(pkt, verdict, rule, info);
  56 }
  57
  58 static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
  59                                     struct nft_verdict *verdict,
  60                                     struct nft_traceinfo *info,
  61                                     const struct nft_rule_dp *rule,
  62                                     enum nft_trace_types type)
  63 {
  64         if (static_branch_unlikely(&nft_trace_enabled)) {
  65                 info->nf_trace = pkt->skb->nf_trace;
  66                 __nft_trace_packet(pkt, verdict, rule, info, type);
  67         }
  68 }
  69
  70 static inline void nft_trace_copy_nftrace(const struct nft_pktinfo *pkt,
  71                                           struct nft_traceinfo *info)
  72 {
  73         if (static_branch_unlikely(&nft_trace_enabled))
  74                 info->nf_trace = pkt->skb->nf_trace;
  75 }
  76
  77 static void nft_bitwise_fast_eval(const struct nft_expr *expr,
  78                                   struct nft_regs *regs)
  79 {
  80         const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
  81         u32 *src = &regs->data[priv->sreg];
  82         u32 *dst = &regs->data[priv->dreg];
  83
  84         *dst = (*src & priv->mask) ^ priv->xor;
  85 }
  86
  87 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  88                               struct nft_regs *regs)
  89 {
  90         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  91
  92         if (((regs->data[priv->sreg] & priv->mask) == priv->data) ^ priv->inv)
  93                 return;
  94         regs->verdict.code = NFT_BREAK;
  95 }
  96
  97 static void nft_cmp16_fast_eval(const struct nft_expr *expr,
  98                                 struct nft_regs *regs)
  99 {
 100         const struct nft_cmp16_fast_expr *priv = nft_expr_priv(expr);
 101         const u64 *reg_data = (const u64 *)&regs->data[priv->sreg];
 102         const u64 *mask = (const u64 *)&priv->mask;
 103         const u64 *data = (const u64 *)&priv->data;
 104
 105         if (((reg_data[0] & mask[0]) == data[0] &&
 106             ((reg_data[1] & mask[1]) == data[1])) ^ priv->inv)
 107                 return;
 108         regs->verdict.code = NFT_BREAK;
 109 }
 110
 111 static noinline void __nft_trace_verdict(const struct nft_pktinfo *pkt,
 112                                          struct nft_traceinfo *info,
 113                                          const struct nft_rule_dp *rule,
 114                                          const struct nft_regs *regs)
 115 {
 116         enum nft_trace_types type;
 117
 118         switch (regs->verdict.code & NF_VERDICT_MASK) {
 119         case NFT_CONTINUE:
 120         case NFT_RETURN:
 121                 type = NFT_TRACETYPE_RETURN;
 122                 break;
 123         case NF_STOLEN:
 124                 type = NFT_TRACETYPE_RULE;
 125                 /* can't access skb->nf_trace; use copy */
 126                 break;
 127         default:
 128                 type = NFT_TRACETYPE_RULE;
 129
 130                 if (info->trace)
 131                         info->nf_trace = pkt->skb->nf_trace;
 132                 break;
 133         }
 134
 135         __nft_trace_packet(pkt, &regs->verdict, rule, info, type);
 136 }
 137
 138 static inline void nft_trace_verdict(const struct nft_pktinfo *pkt,
 139                                      struct nft_traceinfo *info,
 140                                      const struct nft_rule_dp *rule,
 141                                      const struct nft_regs *regs)
 142 {
 143         if (static_branch_unlikely(&nft_trace_enabled))
 144                 __nft_trace_verdict(pkt, info, rule, regs);
 145 }
 146
 147 static bool nft_payload_fast_eval(const struct nft_expr *expr,
 148                                   struct nft_regs *regs,
 149                                   const struct nft_pktinfo *pkt)
 150 {
 151         const struct nft_payload *priv = nft_expr_priv(expr);
 152         const struct sk_buff *skb = pkt->skb;
 153         u32 *dest = &regs->data[priv->dreg];
 154         unsigned char *ptr;
 155
 156         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
 157                 ptr = skb_network_header(skb);
 158         else {
 159                 if (!(pkt->flags & NFT_PKTINFO_L4PROTO))
 160                         return false;
 161                 ptr = skb_network_header(skb) + nft_thoff(pkt);
 162         }
 163
 164         ptr += priv->offset;
 165
 166         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
 167                 return false;
 168
 169         *dest = 0;
 170         if (priv->len == 2)
 171                 *(u16 *)dest = *(u16 *)ptr;
 172         else if (priv->len == 4)
 173                 *(u32 *)dest = *(u32 *)ptr;
 174         else
 175                 *(u8 *)dest = *(u8 *)ptr;
 176         return true;
 177 }
 178
 179 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
 180
 181 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 182                                             const struct nft_pktinfo *pkt)
 183 {
 184         struct nft_base_chain *base_chain;
 185         struct nft_stats __percpu *pstats;
 186         struct nft_stats *stats;
 187
 188         base_chain = nft_base_chain(chain);
 189
 190         pstats = READ_ONCE(base_chain->stats);
 191         if (pstats) {
 192                 local_bh_disable();
 193                 stats = this_cpu_ptr(pstats);
 194                 u64_stats_update_begin(&stats->syncp);
 195                 stats->pkts++;
 196                 stats->bytes += pkt->skb->len;
 197                 u64_stats_update_end(&stats->syncp);
 198                 local_bh_enable();
 199         }
 200 }
 201
 202 struct nft_jumpstack {
 203         const struct nft_rule_dp *rule;
 204 };
 205
 206 static void expr_call_ops_eval(const struct nft_expr *expr,
 207                                struct nft_regs *regs,
 208                                struct nft_pktinfo *pkt)
 209 {
 210 #ifdef CONFIG_RETPOLINE
 211         unsigned long e;
 212
 213         if (nf_skip_indirect_calls())
 214                 goto indirect_call;
 215
 216         e = (unsigned long)expr->ops->eval;
 217 #define X(e, fun) \
 218         do { if ((e) == (unsigned long)(fun)) \
 219                 return fun(expr, regs, pkt); } while (0)
 220
 221         X(e, nft_payload_eval);
 222         X(e, nft_cmp_eval);
 223         X(e, nft_counter_eval);
 224         X(e, nft_meta_get_eval);
 225         X(e, nft_lookup_eval);
 226 #if IS_ENABLED(CONFIG_NFT_CT)
 227         X(e, nft_ct_get_fast_eval);
 228 #endif
 229         X(e, nft_range_eval);
 230         X(e, nft_immediate_eval);
 231         X(e, nft_byteorder_eval);
 232         X(e, nft_dynset_eval);
 233         X(e, nft_rt_get_eval);
 234         X(e, nft_bitwise_eval);
 235         X(e, nft_objref_eval);
 236         X(e, nft_objref_map_eval);
 237 #undef  X
 238 indirect_call:
 239 #endif /* CONFIG_RETPOLINE */
 240         expr->ops->eval(expr, regs, pkt);
 241 }
 242
 243 #define nft_rule_expr_first(rule)       (struct nft_expr *)&rule->data[0]
 244 #define nft_rule_expr_next(expr)        ((void *)expr) + expr->ops->size
 245 #define nft_rule_expr_last(rule)        (struct nft_expr *)&rule->data[rule->dlen]
 246
 247 #define nft_rule_dp_for_each_expr(expr, last, rule) \
 248         for ((expr) = nft_rule_expr_first(rule), (last) = nft_rule_expr_last(rule); \
 249              (expr) != (last); \
 250              (expr) = nft_rule_expr_next(expr))
 251
 252 unsigned int
 253 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 254 {
 255         const struct nft_chain *chain = priv, *basechain = chain;
 256         const struct net *net = nft_net(pkt);
 257         const struct nft_expr *expr, *last;
 258         const struct nft_rule_dp *rule;
 259         struct nft_regs regs = {};
 260         unsigned int stackptr = 0;
 261         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 262         bool genbit = READ_ONCE(net->nft.gencursor);
 263         struct nft_rule_blob *blob;
 264         struct nft_traceinfo info;
 265
 266         info.trace = false;
 267         if (static_branch_unlikely(&nft_trace_enabled))
 268                 nft_trace_init(&info, pkt, basechain);
 269 do_chain:
 270         if (genbit)
 271                 blob = rcu_dereference(chain->blob_gen_1);
 272         else
 273                 blob = rcu_dereference(chain->blob_gen_0);
 274
 275         rule = (struct nft_rule_dp *)blob->data;
 276 next_rule:
 277         regs.verdict.code = NFT_CONTINUE;
 278         for (; !rule->is_last ; rule = nft_rule_next(rule)) {
 279                 nft_rule_dp_for_each_expr(expr, last, rule) {
 280                         if (expr->ops == &nft_cmp_fast_ops)
 281                                 nft_cmp_fast_eval(expr, &regs);
 282                         else if (expr->ops == &nft_cmp16_fast_ops)
 283                                 nft_cmp16_fast_eval(expr, &regs);
 284                         else if (expr->ops == &nft_bitwise_fast_ops)
 285                                 nft_bitwise_fast_eval(expr, &regs);
 286                         else if (expr->ops != &nft_payload_fast_ops ||
 287                                  !nft_payload_fast_eval(expr, &regs, pkt))
 288                                 expr_call_ops_eval(expr, &regs, pkt);
 289
 290                         if (regs.verdict.code != NFT_CONTINUE)
 291                                 break;
 292                 }
 293
 294                 switch (regs.verdict.code) {
 295                 case NFT_BREAK:
 296                         regs.verdict.code = NFT_CONTINUE;
 297                         nft_trace_copy_nftrace(pkt, &info);
 298                         continue;
 299                 case NFT_CONTINUE:
 300                         nft_trace_packet(pkt, &regs.verdict,  &info, rule,
 301                                          NFT_TRACETYPE_RULE);
 302                         continue;
 303                 }
 304                 break;
 305         }
 306
 307         nft_trace_verdict(pkt, &info, rule, &regs);
 308
 309         switch (regs.verdict.code & NF_VERDICT_MASK) {
 310         case NF_ACCEPT:
 311         case NF_QUEUE:
 312         case NF_STOLEN:
 313                 return regs.verdict.code;
 314         case NF_DROP:
 315                 return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);
 316         }
 317
 318         switch (regs.verdict.code) {
 319         case NFT_JUMP:
 320                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 321                         return NF_DROP;
 322                 jumpstack[stackptr].rule = nft_rule_next(rule);
 323                 stackptr++;
 324                 fallthrough;
 325         case NFT_GOTO:
 326                 chain = regs.verdict.chain;
 327                 goto do_chain;
 328         case NFT_CONTINUE:
 329         case NFT_RETURN:
 330                 break;
 331         default:
 332                 WARN_ON_ONCE(1);
 333         }
 334
 335         if (stackptr > 0) {
 336                 stackptr--;
 337                 rule = jumpstack[stackptr].rule;
 338                 goto next_rule;
 339         }
 340
 341         nft_trace_packet(pkt, &regs.verdict, &info, NULL, NFT_TRACETYPE_POLICY);
 342
 343         if (static_branch_unlikely(&nft_counters_enabled))
 344                 nft_update_chain_stats(basechain, pkt);
 345
 346         if (nft_base_chain(basechain)->policy == NF_DROP)
 347                 return NF_DROP_REASON(pkt->skb, SKB_DROP_REASON_NETFILTER_DROP, EPERM);
 348
 349         return nft_base_chain(basechain)->policy;
 350 }
 351 EXPORT_SYMBOL_GPL(nft_do_chain);
 352
 353 static struct nft_expr_type *nft_basic_types[] = {
 354         &nft_imm_type,
 355         &nft_cmp_type,
 356         &nft_lookup_type,
 357         &nft_bitwise_type,
 358         &nft_byteorder_type,
 359         &nft_payload_type,
 360         &nft_dynset_type,
 361         &nft_range_type,
 362         &nft_meta_type,
 363         &nft_rt_type,
 364         &nft_exthdr_type,
 365         &nft_last_type,
 366         &nft_counter_type,
 367         &nft_objref_type,
 368         &nft_inner_type,
 369 };
 370
 371 static struct nft_object_type *nft_basic_objects[] = {
 372 #ifdef CONFIG_NETWORK_SECMARK
 373         &nft_secmark_obj_type,
 374 #endif
 375         &nft_counter_obj_type,
 376 };
 377
 378 int __init nf_tables_core_module_init(void)
 379 {
 380         int err, i, j = 0;
 381
 382         nft_counter_init_seqcount();
 383
 384         for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
 385                 err = nft_register_obj(nft_basic_objects[i]);
 386                 if (err)
 387                         goto err;
 388         }
 389
 390         for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
 391                 err = nft_register_expr(nft_basic_types[j]);
 392                 if (err)
 393                         goto err;
 394         }
 395
 396         nf_skip_indirect_calls_enable();
 397
 398         return 0;
 399
 400 err:
 401         while (j-- > 0)
 402                 nft_unregister_expr(nft_basic_types[j]);
 403
 404         while (i-- > 0)
 405                 nft_unregister_obj(nft_basic_objects[i]);
 406
 407         return err;
 408 }
 409
 410 void nf_tables_core_module_exit(void)
 411 {
 412         int i;
 413
 414         i = ARRAY_SIZE(nft_basic_types);
 415         while (i-- > 0)
 416                 nft_unregister_expr(nft_basic_types[i]);
 417
 418         i = ARRAY_SIZE(nft_basic_objects);
 419         while (i-- > 0)
 420                 nft_unregister_obj(nft_basic_objects[i]);
 421 }