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