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