net/netfilter/nf_tables_core.c

   1 /*
   2  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/list.h>
  15 #include <linux/rculist.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/netlink.h>
  18 #include <linux/netfilter.h>
  19 #include <linux/static_key.h>
  20 #include <linux/netfilter/nfnetlink.h>
  21 #include <linux/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_tables_core.h>
  23 #include <net/netfilter/nf_tables.h>
  24 #include <net/netfilter/nf_log.h>
  25
  26 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
  27                                         const struct nft_chain *chain,
  28                                         enum nft_trace_types type)
  29 {
  30         const struct nft_pktinfo *pkt = info->pkt;
  31
  32         if (!info->trace || !pkt->skb->nf_trace)
  33                 return;
  34
  35         info->chain = chain;
  36         info->type = type;
  37
  38         nft_trace_notify(info);
  39 }
  40
  41 static inline void nft_trace_packet(struct nft_traceinfo *info,
  42                                     const struct nft_chain *chain,
  43                                     const struct nft_rule *rule,
  44                                     enum nft_trace_types type)
  45 {
  46         if (static_branch_unlikely(&nft_trace_enabled)) {
  47                 info->rule = rule;
  48                 __nft_trace_packet(info, chain, type);
  49         }
  50 }
  51
  52 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  53                               struct nft_regs *regs)
  54 {
  55         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  56         u32 mask = nft_cmp_fast_mask(priv->len);
  57
  58         if ((regs->data[priv->sreg] & mask) == priv->data)
  59                 return;
  60         regs->verdict.code = NFT_BREAK;
  61 }
  62
  63 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  64                                   struct nft_regs *regs,
  65                                   const struct nft_pktinfo *pkt)
  66 {
  67         const struct nft_payload *priv = nft_expr_priv(expr);
  68         const struct sk_buff *skb = pkt->skb;
  69         u32 *dest = &regs->data[priv->dreg];
  70         unsigned char *ptr;
  71
  72         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  73                 ptr = skb_network_header(skb);
  74         else {
  75                 if (!pkt->tprot_set)
  76                         return false;
  77                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  78         }
  79
  80         ptr += priv->offset;
  81
  82         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
  83                 return false;
  84
  85         *dest = 0;
  86         if (priv->len == 2)
  87                 *(u16 *)dest = *(u16 *)ptr;
  88         else if (priv->len == 4)
  89                 *(u32 *)dest = *(u32 *)ptr;
  90         else
  91                 *(u8 *)dest = *(u8 *)ptr;
  92         return true;
  93 }
  94
  95 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
  96
  97 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
  98                                             const struct nft_pktinfo *pkt)
  99 {
 100         struct nft_base_chain *base_chain;
 101         struct nft_stats *stats;
 102
 103         base_chain = nft_base_chain(chain);
 104         if (!base_chain->stats)
 105                 return;
 106
 107         local_bh_disable();
 108         stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
 109         if (stats) {
 110                 u64_stats_update_begin(&stats->syncp);
 111                 stats->pkts++;
 112                 stats->bytes += pkt->skb->len;
 113                 u64_stats_update_end(&stats->syncp);
 114         }
 115         local_bh_enable();
 116 }
 117
 118 struct nft_jumpstack {
 119         const struct nft_chain  *chain;
 120         struct nft_rule *const *rules;
 121 };
 122
 123 static void expr_call_ops_eval(const struct nft_expr *expr,
 124                                struct nft_regs *regs,
 125                                struct nft_pktinfo *pkt)
 126 {
 127         unsigned long e = (unsigned long)expr->ops->eval;
 128
 129         if (e == (unsigned long)nft_meta_get_eval)
 130                 nft_meta_get_eval(expr, regs, pkt);
 131         else if (e == (unsigned long)nft_lookup_eval)
 132                 nft_lookup_eval(expr, regs, pkt);
 133         else
 134                 expr->ops->eval(expr, regs, pkt);
 135 }
 136
 137 unsigned int
 138 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 139 {
 140         const struct nft_chain *chain = priv, *basechain = chain;
 141         const struct net *net = nft_net(pkt);
 142         struct nft_rule *const *rules;
 143         const struct nft_rule *rule;
 144         const struct nft_expr *expr, *last;
 145         struct nft_regs regs;
 146         unsigned int stackptr = 0;
 147         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 148         bool genbit = READ_ONCE(net->nft.gencursor);
 149         struct nft_traceinfo info;
 150
 151         info.trace = false;
 152         if (static_branch_unlikely(&nft_trace_enabled))
 153                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 154 do_chain:
 155         if (genbit)
 156                 rules = rcu_dereference(chain->rules_gen_1);
 157         else
 158                 rules = rcu_dereference(chain->rules_gen_0);
 159
 160 next_rule:
 161         rule = *rules;
 162         regs.verdict.code = NFT_CONTINUE;
 163         for (; *rules ; rules++) {
 164                 rule = *rules;
 165                 nft_rule_for_each_expr(expr, last, rule) {
 166                         if (expr->ops == &nft_cmp_fast_ops)
 167                                 nft_cmp_fast_eval(expr, &regs);
 168                         else if (expr->ops != &nft_payload_fast_ops ||
 169                                  !nft_payload_fast_eval(expr, &regs, pkt))
 170                                 expr_call_ops_eval(expr, &regs, pkt);
 171
 172                         if (regs.verdict.code != NFT_CONTINUE)
 173                                 break;
 174                 }
 175
 176                 switch (regs.verdict.code) {
 177                 case NFT_BREAK:
 178                         regs.verdict.code = NFT_CONTINUE;
 179                         continue;
 180                 case NFT_CONTINUE:
 181                         nft_trace_packet(&info, chain, rule,
 182                                          NFT_TRACETYPE_RULE);
 183                         continue;
 184                 }
 185                 break;
 186         }
 187
 188         switch (regs.verdict.code & NF_VERDICT_MASK) {
 189         case NF_ACCEPT:
 190         case NF_DROP:
 191         case NF_QUEUE:
 192         case NF_STOLEN:
 193                 nft_trace_packet(&info, chain, rule,
 194                                  NFT_TRACETYPE_RULE);
 195                 return regs.verdict.code;
 196         }
 197
 198         switch (regs.verdict.code) {
 199         case NFT_JUMP:
 200                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 201                         return NF_DROP;
 202                 jumpstack[stackptr].chain = chain;
 203                 jumpstack[stackptr].rules = rules + 1;
 204                 stackptr++;
 205                 /* fall through */
 206         case NFT_GOTO:
 207                 nft_trace_packet(&info, chain, rule,
 208                                  NFT_TRACETYPE_RULE);
 209
 210                 chain = regs.verdict.chain;
 211                 goto do_chain;
 212         case NFT_CONTINUE:
 213                 /* fall through */
 214         case NFT_RETURN:
 215                 nft_trace_packet(&info, chain, rule,
 216                                  NFT_TRACETYPE_RETURN);
 217                 break;
 218         default:
 219                 WARN_ON(1);
 220         }
 221
 222         if (stackptr > 0) {
 223                 stackptr--;
 224                 chain = jumpstack[stackptr].chain;
 225                 rules = jumpstack[stackptr].rules;
 226                 goto next_rule;
 227         }
 228
 229         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 230
 231         if (static_branch_unlikely(&nft_counters_enabled))
 232                 nft_update_chain_stats(basechain, pkt);
 233
 234         return nft_base_chain(basechain)->policy;
 235 }
 236 EXPORT_SYMBOL_GPL(nft_do_chain);
 237
 238 static struct nft_expr_type *nft_basic_types[] = {
 239         &nft_imm_type,
 240         &nft_cmp_type,
 241         &nft_lookup_type,
 242         &nft_bitwise_type,
 243         &nft_byteorder_type,
 244         &nft_payload_type,
 245         &nft_dynset_type,
 246         &nft_range_type,
 247         &nft_meta_type,
 248         &nft_rt_type,
 249         &nft_exthdr_type,
 250 };
 251
 252 static struct nft_object_type *nft_basic_objects[] = {
 253 #ifdef CONFIG_NETWORK_SECMARK
 254         &nft_secmark_obj_type,
 255 #endif
 256 };
 257
 258 int __init nf_tables_core_module_init(void)
 259 {
 260         int err, i, j = 0;
 261
 262         for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
 263                 err = nft_register_obj(nft_basic_objects[i]);
 264                 if (err)
 265                         goto err;
 266         }
 267
 268         for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
 269                 err = nft_register_expr(nft_basic_types[j]);
 270                 if (err)
 271                         goto err;
 272         }
 273
 274         return 0;
 275
 276 err:
 277         while (j-- > 0)
 278                 nft_unregister_expr(nft_basic_types[j]);
 279
 280         while (i-- > 0)
 281                 nft_unregister_obj(nft_basic_objects[i]);
 282
 283         return err;
 284 }
 285
 286 void nf_tables_core_module_exit(void)
 287 {
 288         int i;
 289
 290         i = ARRAY_SIZE(nft_basic_types);
 291         while (i-- > 0)
 292                 nft_unregister_expr(nft_basic_types[i]);
 293
 294         i = ARRAY_SIZE(nft_basic_objects);
 295         while (i-- > 0)
 296                 nft_unregister_obj(nft_basic_objects[i]);
 297 }