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 *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 *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         rcu_read_lock();
 144         pstats = READ_ONCE(base_chain->stats);
 145         if (pstats) {
 146                 local_bh_disable();
 147                 stats = this_cpu_ptr(pstats);
 148                 u64_stats_update_begin(&stats->syncp);
 149                 stats->pkts++;
 150                 stats->bytes += pkt->skb->len;
 151                 u64_stats_update_end(&stats->syncp);
 152                 local_bh_enable();
 153         }
 154         rcu_read_unlock();
 155 }
 156
 157 struct nft_jumpstack {
 158         const struct nft_chain  *chain;
 159         struct nft_rule *const *rules;
 160 };
 161
 162 static void expr_call_ops_eval(const struct nft_expr *expr,
 163                                struct nft_regs *regs,
 164                                struct nft_pktinfo *pkt)
 165 {
 166 #ifdef CONFIG_RETPOLINE
 167         unsigned long e = (unsigned long)expr->ops->eval;
 168 #define X(e, fun) \
 169         do { if ((e) == (unsigned long)(fun)) \
 170                 return fun(expr, regs, pkt); } while (0)
 171
 172         X(e, nft_payload_eval);
 173         X(e, nft_cmp_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 unsigned int
 188 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 189 {
 190         const struct nft_chain *chain = priv, *basechain = chain;
 191         const struct net *net = nft_net(pkt);
 192         struct nft_rule *const *rules;
 193         const struct nft_rule *rule;
 194         const struct nft_expr *expr, *last;
 195         struct nft_regs regs = {};
 196         unsigned int stackptr = 0;
 197         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 198         bool genbit = READ_ONCE(net->nft.gencursor);
 199         struct nft_traceinfo info;
 200
 201         info.trace = false;
 202         if (static_branch_unlikely(&nft_trace_enabled))
 203                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 204 do_chain:
 205         if (genbit)
 206                 rules = rcu_dereference(chain->rules_gen_1);
 207         else
 208                 rules = rcu_dereference(chain->rules_gen_0);
 209
 210 next_rule:
 211         rule = *rules;
 212         regs.verdict.code = NFT_CONTINUE;
 213         for (; *rules ; rules++) {
 214                 rule = *rules;
 215                 nft_rule_for_each_expr(expr, last, rule) {
 216                         if (expr->ops == &nft_cmp_fast_ops)
 217                                 nft_cmp_fast_eval(expr, &regs);
 218                         else if (expr->ops == &nft_bitwise_fast_ops)
 219                                 nft_bitwise_fast_eval(expr, &regs);
 220                         else if (expr->ops != &nft_payload_fast_ops ||
 221                                  !nft_payload_fast_eval(expr, &regs, pkt))
 222                                 expr_call_ops_eval(expr, &regs, pkt);
 223
 224                         if (regs.verdict.code != NFT_CONTINUE)
 225                                 break;
 226                 }
 227
 228                 switch (regs.verdict.code) {
 229                 case NFT_BREAK:
 230                         regs.verdict.code = NFT_CONTINUE;
 231                         continue;
 232                 case NFT_CONTINUE:
 233                         nft_trace_packet(&info, chain, rule,
 234                                          NFT_TRACETYPE_RULE);
 235                         continue;
 236                 }
 237                 break;
 238         }
 239
 240         nft_trace_verdict(&info, chain, rule, &regs);
 241
 242         switch (regs.verdict.code & NF_VERDICT_MASK) {
 243         case NF_ACCEPT:
 244         case NF_DROP:
 245         case NF_QUEUE:
 246         case NF_STOLEN:
 247                 return regs.verdict.code;
 248         }
 249
 250         switch (regs.verdict.code) {
 251         case NFT_JUMP:
 252                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 253                         return NF_DROP;
 254                 jumpstack[stackptr].chain = chain;
 255                 jumpstack[stackptr].rules = rules + 1;
 256                 stackptr++;
 257                 fallthrough;
 258         case NFT_GOTO:
 259                 chain = regs.verdict.chain;
 260                 goto do_chain;
 261         case NFT_CONTINUE:
 262         case NFT_RETURN:
 263                 break;
 264         default:
 265                 WARN_ON(1);
 266         }
 267
 268         if (stackptr > 0) {
 269                 stackptr--;
 270                 chain = jumpstack[stackptr].chain;
 271                 rules = jumpstack[stackptr].rules;
 272                 goto next_rule;
 273         }
 274
 275         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 276
 277         if (static_branch_unlikely(&nft_counters_enabled))
 278                 nft_update_chain_stats(basechain, pkt);
 279
 280         return nft_base_chain(basechain)->policy;
 281 }
 282 EXPORT_SYMBOL_GPL(nft_do_chain);
 283
 284 static struct nft_expr_type *nft_basic_types[] = {
 285         &nft_imm_type,
 286         &nft_cmp_type,
 287         &nft_lookup_type,
 288         &nft_bitwise_type,
 289         &nft_byteorder_type,
 290         &nft_payload_type,
 291         &nft_dynset_type,
 292         &nft_range_type,
 293         &nft_meta_type,
 294         &nft_rt_type,
 295         &nft_exthdr_type,
 296         &nft_last_type,
 297 };
 298
 299 static struct nft_object_type *nft_basic_objects[] = {
 300 #ifdef CONFIG_NETWORK_SECMARK
 301         &nft_secmark_obj_type,
 302 #endif
 303 };
 304
 305 int __init nf_tables_core_module_init(void)
 306 {
 307         int err, i, j = 0;
 308
 309         for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
 310                 err = nft_register_obj(nft_basic_objects[i]);
 311                 if (err)
 312                         goto err;
 313         }
 314
 315         for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
 316                 err = nft_register_expr(nft_basic_types[j]);
 317                 if (err)
 318                         goto err;
 319         }
 320
 321         return 0;
 322
 323 err:
 324         while (j-- > 0)
 325                 nft_unregister_expr(nft_basic_types[j]);
 326
 327         while (i-- > 0)
 328                 nft_unregister_obj(nft_basic_objects[i]);
 329
 330         return err;
 331 }
 332
 333 void nf_tables_core_module_exit(void)
 334 {
 335         int i;
 336
 337         i = ARRAY_SIZE(nft_basic_types);
 338         while (i-- > 0)
 339                 nft_unregister_expr(nft_basic_types[i]);
 340
 341         i = ARRAY_SIZE(nft_basic_objects);
 342         while (i-- > 0)
 343                 nft_unregister_obj(nft_basic_objects[i]);
 344 }