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