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 const char *const comments[__NFT_TRACETYPE_MAX] = {
  27         [NFT_TRACETYPE_POLICY]  = "policy",
  28         [NFT_TRACETYPE_RETURN]  = "return",
  29         [NFT_TRACETYPE_RULE]    = "rule",
  30 };
  31
  32 static const struct nf_loginfo trace_loginfo = {
  33         .type = NF_LOG_TYPE_LOG,
  34         .u = {
  35                 .log = {
  36                         .level = LOGLEVEL_WARNING,
  37                         .logflags = NF_LOG_DEFAULT_MASK,
  38                 },
  39         },
  40 };
  41
  42 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
  43                                         const struct nft_chain *chain,
  44                                         enum nft_trace_types type)
  45 {
  46         const struct nft_pktinfo *pkt = info->pkt;
  47
  48         if (!info->trace || !pkt->skb->nf_trace)
  49                 return;
  50
  51         info->chain = chain;
  52         info->type = type;
  53
  54         nft_trace_notify(info);
  55 }
  56
  57 static inline void nft_trace_packet(struct nft_traceinfo *info,
  58                                     const struct nft_chain *chain,
  59                                     const struct nft_rule *rule,
  60                                     enum nft_trace_types type)
  61 {
  62         if (static_branch_unlikely(&nft_trace_enabled)) {
  63                 info->rule = rule;
  64                 __nft_trace_packet(info, chain, type);
  65         }
  66 }
  67
  68 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  69                               struct nft_regs *regs)
  70 {
  71         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  72         u32 mask = nft_cmp_fast_mask(priv->len);
  73
  74         if ((regs->data[priv->sreg] & mask) == priv->data)
  75                 return;
  76         regs->verdict.code = NFT_BREAK;
  77 }
  78
  79 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  80                                   struct nft_regs *regs,
  81                                   const struct nft_pktinfo *pkt)
  82 {
  83         const struct nft_payload *priv = nft_expr_priv(expr);
  84         const struct sk_buff *skb = pkt->skb;
  85         u32 *dest = &regs->data[priv->dreg];
  86         unsigned char *ptr;
  87
  88         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  89                 ptr = skb_network_header(skb);
  90         else {
  91                 if (!pkt->tprot_set)
  92                         return false;
  93                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  94         }
  95
  96         ptr += priv->offset;
  97
  98         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
  99                 return false;
 100
 101         *dest = 0;
 102         if (priv->len == 2)
 103                 *(u16 *)dest = *(u16 *)ptr;
 104         else if (priv->len == 4)
 105                 *(u32 *)dest = *(u32 *)ptr;
 106         else
 107                 *(u8 *)dest = *(u8 *)ptr;
 108         return true;
 109 }
 110
 111 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
 112
 113 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 114                                             const struct nft_pktinfo *pkt)
 115 {
 116         struct nft_base_chain *base_chain;
 117         struct nft_stats *stats;
 118
 119         base_chain = nft_base_chain(chain);
 120         if (!base_chain->stats)
 121                 return;
 122
 123         stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
 124         if (stats) {
 125                 local_bh_disable();
 126                 u64_stats_update_begin(&stats->syncp);
 127                 stats->pkts++;
 128                 stats->bytes += pkt->skb->len;
 129                 u64_stats_update_end(&stats->syncp);
 130                 local_bh_enable();
 131         }
 132 }
 133
 134 struct nft_jumpstack {
 135         const struct nft_chain  *chain;
 136         const struct nft_rule   *rule;
 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         const struct nft_rule *rule;
 145         const struct nft_expr *expr, *last;
 146         struct nft_regs regs;
 147         unsigned int stackptr = 0;
 148         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 149         unsigned int gencursor = nft_genmask_cur(net);
 150         struct nft_traceinfo info;
 151
 152         info.trace = false;
 153         if (static_branch_unlikely(&nft_trace_enabled))
 154                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 155 do_chain:
 156         rule = list_entry(&chain->rules, struct nft_rule, list);
 157 next_rule:
 158         regs.verdict.code = NFT_CONTINUE;
 159         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 160
 161                 /* This rule is not active, skip. */
 162                 if (unlikely(rule->genmask & gencursor))
 163                         continue;
 164
 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->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                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 201                 jumpstack[stackptr].chain = chain;
 202                 jumpstack[stackptr].rule  = rule;
 203                 stackptr++;
 204                 /* fall through */
 205         case NFT_GOTO:
 206                 nft_trace_packet(&info, chain, rule,
 207                                  NFT_TRACETYPE_RULE);
 208
 209                 chain = regs.verdict.chain;
 210                 goto do_chain;
 211         case NFT_CONTINUE:
 212                 /* fall through */
 213         case NFT_RETURN:
 214                 nft_trace_packet(&info, chain, rule,
 215                                  NFT_TRACETYPE_RETURN);
 216                 break;
 217         default:
 218                 WARN_ON(1);
 219         }
 220
 221         if (stackptr > 0) {
 222                 stackptr--;
 223                 chain = jumpstack[stackptr].chain;
 224                 rule  = jumpstack[stackptr].rule;
 225                 goto next_rule;
 226         }
 227
 228         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 229
 230         if (static_branch_unlikely(&nft_counters_enabled))
 231                 nft_update_chain_stats(basechain, pkt);
 232
 233         return nft_base_chain(basechain)->policy;
 234 }
 235 EXPORT_SYMBOL_GPL(nft_do_chain);
 236
 237 static struct nft_expr_type *nft_basic_types[] = {
 238         &nft_imm_type,
 239         &nft_cmp_type,
 240         &nft_lookup_type,
 241         &nft_bitwise_type,
 242         &nft_byteorder_type,
 243         &nft_payload_type,
 244         &nft_dynset_type,
 245         &nft_range_type,
 246         &nft_meta_type,
 247         &nft_rt_type,
 248         &nft_exthdr_type,
 249 };
 250
 251 int __init nf_tables_core_module_init(void)
 252 {
 253         int err, i;
 254
 255         for (i = 0; i < ARRAY_SIZE(nft_basic_types); i++) {
 256                 err = nft_register_expr(nft_basic_types[i]);
 257                 if (err)
 258                         goto err;
 259         }
 260
 261         return 0;
 262
 263 err:
 264         while (i-- > 0)
 265                 nft_unregister_expr(nft_basic_types[i]);
 266         return err;
 267 }
 268
 269 void nf_tables_core_module_exit(void)
 270 {
 271         int i;
 272
 273         i = ARRAY_SIZE(nft_basic_types);
 274         while (i-- > 0)
 275                 nft_unregister_expr(nft_basic_types[i]);
 276 }