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 __percpu *pstats;
 102         struct nft_stats *stats;
 103
 104         base_chain = nft_base_chain(chain);
 105
 106         rcu_read_lock();
 107         pstats = READ_ONCE(base_chain->stats);
 108         if (pstats) {
 109                 local_bh_disable();
 110                 stats = this_cpu_ptr(pstats);
 111                 u64_stats_update_begin(&stats->syncp);
 112                 stats->pkts++;
 113                 stats->bytes += pkt->skb->len;
 114                 u64_stats_update_end(&stats->syncp);
 115                 local_bh_enable();
 116         }
 117         rcu_read_unlock();
 118 }
 119
 120 struct nft_jumpstack {
 121         const struct nft_chain  *chain;
 122         struct nft_rule *const *rules;
 123 };
 124
 125 static void expr_call_ops_eval(const struct nft_expr *expr,
 126                                struct nft_regs *regs,
 127                                struct nft_pktinfo *pkt)
 128 {
 129         unsigned long e = (unsigned long)expr->ops->eval;
 130
 131         if (e == (unsigned long)nft_meta_get_eval)
 132                 nft_meta_get_eval(expr, regs, pkt);
 133         else if (e == (unsigned long)nft_lookup_eval)
 134                 nft_lookup_eval(expr, regs, pkt);
 135         else
 136                 expr->ops->eval(expr, regs, pkt);
 137 }
 138
 139 unsigned int
 140 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 141 {
 142         const struct nft_chain *chain = priv, *basechain = chain;
 143         const struct net *net = nft_net(pkt);
 144         struct nft_rule *const *rules;
 145         const struct nft_rule *rule;
 146         const struct nft_expr *expr, *last;
 147         struct nft_regs regs;
 148         unsigned int stackptr = 0;
 149         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 150         bool genbit = READ_ONCE(net->nft.gencursor);
 151         struct nft_traceinfo info;
 152
 153         info.trace = false;
 154         if (static_branch_unlikely(&nft_trace_enabled))
 155                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 156 do_chain:
 157         if (genbit)
 158                 rules = rcu_dereference(chain->rules_gen_1);
 159         else
 160                 rules = rcu_dereference(chain->rules_gen_0);
 161
 162 next_rule:
 163         rule = *rules;
 164         regs.verdict.code = NFT_CONTINUE;
 165         for (; *rules ; rules++) {
 166                 rule = *rules;
 167                 nft_rule_for_each_expr(expr, last, rule) {
 168                         if (expr->ops == &nft_cmp_fast_ops)
 169                                 nft_cmp_fast_eval(expr, &regs);
 170                         else if (expr->ops != &nft_payload_fast_ops ||
 171                                  !nft_payload_fast_eval(expr, &regs, pkt))
 172                                 expr_call_ops_eval(expr, &regs, pkt);
 173
 174                         if (regs.verdict.code != NFT_CONTINUE)
 175                                 break;
 176                 }
 177
 178                 switch (regs.verdict.code) {
 179                 case NFT_BREAK:
 180                         regs.verdict.code = NFT_CONTINUE;
 181                         continue;
 182                 case NFT_CONTINUE:
 183                         nft_trace_packet(&info, chain, rule,
 184                                          NFT_TRACETYPE_RULE);
 185                         continue;
 186                 }
 187                 break;
 188         }
 189
 190         switch (regs.verdict.code & NF_VERDICT_MASK) {
 191         case NF_ACCEPT:
 192         case NF_DROP:
 193         case NF_QUEUE:
 194         case NF_STOLEN:
 195                 nft_trace_packet(&info, chain, rule,
 196                                  NFT_TRACETYPE_RULE);
 197                 return regs.verdict.code;
 198         }
 199
 200         switch (regs.verdict.code) {
 201         case NFT_JUMP:
 202                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 203                         return NF_DROP;
 204                 jumpstack[stackptr].chain = chain;
 205                 jumpstack[stackptr].rules = rules + 1;
 206                 stackptr++;
 207                 /* fall through */
 208         case NFT_GOTO:
 209                 nft_trace_packet(&info, chain, rule,
 210                                  NFT_TRACETYPE_RULE);
 211
 212                 chain = regs.verdict.chain;
 213                 goto do_chain;
 214         case NFT_CONTINUE:
 215                 /* fall through */
 216         case NFT_RETURN:
 217                 nft_trace_packet(&info, chain, rule,
 218                                  NFT_TRACETYPE_RETURN);
 219                 break;
 220         default:
 221                 WARN_ON(1);
 222         }
 223
 224         if (stackptr > 0) {
 225                 stackptr--;
 226                 chain = jumpstack[stackptr].chain;
 227                 rules = jumpstack[stackptr].rules;
 228                 goto next_rule;
 229         }
 230
 231         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 232
 233         if (static_branch_unlikely(&nft_counters_enabled))
 234                 nft_update_chain_stats(basechain, pkt);
 235
 236         return nft_base_chain(basechain)->policy;
 237 }
 238 EXPORT_SYMBOL_GPL(nft_do_chain);
 239
 240 static struct nft_expr_type *nft_basic_types[] = {
 241         &nft_imm_type,
 242         &nft_cmp_type,
 243         &nft_lookup_type,
 244         &nft_bitwise_type,
 245         &nft_byteorder_type,
 246         &nft_payload_type,
 247         &nft_dynset_type,
 248         &nft_range_type,
 249         &nft_meta_type,
 250         &nft_rt_type,
 251         &nft_exthdr_type,
 252 };
 253
 254 int __init nf_tables_core_module_init(void)
 255 {
 256         int err, i;
 257
 258         for (i = 0; i < ARRAY_SIZE(nft_basic_types); i++) {
 259                 err = nft_register_expr(nft_basic_types[i]);
 260                 if (err)
 261                         goto err;
 262         }
 263
 264         return 0;
 265
 266 err:
 267         while (i-- > 0)
 268                 nft_unregister_expr(nft_basic_types[i]);
 269         return err;
 270 }
 271
 272 void nf_tables_core_module_exit(void)
 273 {
 274         int i;
 275
 276         i = ARRAY_SIZE(nft_basic_types);
 277         while (i-- > 0)
 278                 nft_unregister_expr(nft_basic_types[i]);
 279 }