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                                         int rulenum, 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         nf_log_trace(nft_net(pkt), nft_pf(pkt), nft_hook(pkt), pkt->skb,
  57                      nft_in(pkt), nft_out(pkt), &trace_loginfo,
  58                      "TRACE: %s:%s:%s:%u ",
  59                      chain->table->name, chain->name, comments[type], rulenum);
  60 }
  61
  62 static inline void nft_trace_packet(struct nft_traceinfo *info,
  63                                     const struct nft_chain *chain,
  64                                     const struct nft_rule *rule,
  65                                     int rulenum,
  66                                     enum nft_trace_types type)
  67 {
  68         if (static_branch_unlikely(&nft_trace_enabled)) {
  69                 info->rule = rule;
  70                 __nft_trace_packet(info, chain, rulenum, type);
  71         }
  72 }
  73
  74 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  75                               struct nft_regs *regs)
  76 {
  77         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  78         u32 mask = nft_cmp_fast_mask(priv->len);
  79
  80         if ((regs->data[priv->sreg] & mask) == priv->data)
  81                 return;
  82         regs->verdict.code = NFT_BREAK;
  83 }
  84
  85 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  86                                   struct nft_regs *regs,
  87                                   const struct nft_pktinfo *pkt)
  88 {
  89         const struct nft_payload *priv = nft_expr_priv(expr);
  90         const struct sk_buff *skb = pkt->skb;
  91         u32 *dest = &regs->data[priv->dreg];
  92         unsigned char *ptr;
  93
  94         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  95                 ptr = skb_network_header(skb);
  96         else {
  97                 if (!pkt->tprot_set)
  98                         return false;
  99                 ptr = skb_network_header(skb) + pkt->xt.thoff;
 100         }
 101
 102         ptr += priv->offset;
 103
 104         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
 105                 return false;
 106
 107         *dest = 0;
 108         if (priv->len == 2)
 109                 *(u16 *)dest = *(u16 *)ptr;
 110         else if (priv->len == 4)
 111                 *(u32 *)dest = *(u32 *)ptr;
 112         else
 113                 *(u8 *)dest = *(u8 *)ptr;
 114         return true;
 115 }
 116
 117 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
 118
 119 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 120                                             const struct nft_pktinfo *pkt)
 121 {
 122         struct nft_base_chain *base_chain;
 123         struct nft_stats __percpu *pstats;
 124         struct nft_stats *stats;
 125
 126         base_chain = nft_base_chain(chain);
 127
 128         rcu_read_lock();
 129         pstats = READ_ONCE(base_chain->stats);
 130         if (pstats) {
 131                 local_bh_disable();
 132                 stats = this_cpu_ptr(pstats);
 133                 u64_stats_update_begin(&stats->syncp);
 134                 stats->pkts++;
 135                 stats->bytes += pkt->skb->len;
 136                 u64_stats_update_end(&stats->syncp);
 137                 local_bh_enable();
 138         }
 139         rcu_read_unlock();
 140 }
 141
 142 struct nft_jumpstack {
 143         const struct nft_chain  *chain;
 144         const struct nft_rule   *rule;
 145         int                     rulenum;
 146 };
 147
 148 unsigned int
 149 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 150 {
 151         const struct nft_chain *chain = priv, *basechain = chain;
 152         const struct net *net = nft_net(pkt);
 153         const struct nft_rule *rule;
 154         const struct nft_expr *expr, *last;
 155         struct nft_regs regs;
 156         unsigned int stackptr = 0;
 157         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 158         int rulenum;
 159         unsigned int gencursor = nft_genmask_cur(net);
 160         struct nft_traceinfo info;
 161
 162         info.trace = false;
 163         if (static_branch_unlikely(&nft_trace_enabled))
 164                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 165 do_chain:
 166         rulenum = 0;
 167         rule = list_entry(&chain->rules, struct nft_rule, list);
 168 next_rule:
 169         regs.verdict.code = NFT_CONTINUE;
 170         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 171
 172                 /* This rule is not active, skip. */
 173                 if (unlikely(rule->genmask & gencursor))
 174                         continue;
 175
 176                 rulenum++;
 177
 178                 nft_rule_for_each_expr(expr, last, rule) {
 179                         if (expr->ops == &nft_cmp_fast_ops)
 180                                 nft_cmp_fast_eval(expr, &regs);
 181                         else if (expr->ops != &nft_payload_fast_ops ||
 182                                  !nft_payload_fast_eval(expr, &regs, pkt))
 183                                 expr->ops->eval(expr, &regs, pkt);
 184
 185                         if (regs.verdict.code != NFT_CONTINUE)
 186                                 break;
 187                 }
 188
 189                 switch (regs.verdict.code) {
 190                 case NFT_BREAK:
 191                         regs.verdict.code = NFT_CONTINUE;
 192                         continue;
 193                 case NFT_CONTINUE:
 194                         nft_trace_packet(&info, chain, rule,
 195                                          rulenum, NFT_TRACETYPE_RULE);
 196                         continue;
 197                 }
 198                 break;
 199         }
 200
 201         switch (regs.verdict.code & NF_VERDICT_MASK) {
 202         case NF_ACCEPT:
 203         case NF_DROP:
 204         case NF_QUEUE:
 205         case NF_STOLEN:
 206                 nft_trace_packet(&info, chain, rule,
 207                                  rulenum, NFT_TRACETYPE_RULE);
 208                 return regs.verdict.code;
 209         }
 210
 211         switch (regs.verdict.code) {
 212         case NFT_JUMP:
 213                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 214                         return NF_DROP;
 215                 jumpstack[stackptr].chain = chain;
 216                 jumpstack[stackptr].rule  = rule;
 217                 jumpstack[stackptr].rulenum = rulenum;
 218                 stackptr++;
 219                 /* fall through */
 220         case NFT_GOTO:
 221                 nft_trace_packet(&info, chain, rule,
 222                                  rulenum, NFT_TRACETYPE_RULE);
 223
 224                 chain = regs.verdict.chain;
 225                 goto do_chain;
 226         case NFT_CONTINUE:
 227                 rulenum++;
 228                 /* fall through */
 229         case NFT_RETURN:
 230                 nft_trace_packet(&info, chain, rule,
 231                                  rulenum, NFT_TRACETYPE_RETURN);
 232                 break;
 233         default:
 234                 WARN_ON(1);
 235         }
 236
 237         if (stackptr > 0) {
 238                 stackptr--;
 239                 chain = jumpstack[stackptr].chain;
 240                 rule  = jumpstack[stackptr].rule;
 241                 rulenum = jumpstack[stackptr].rulenum;
 242                 goto next_rule;
 243         }
 244
 245         nft_trace_packet(&info, basechain, NULL, -1,
 246                          NFT_TRACETYPE_POLICY);
 247
 248         if (static_branch_unlikely(&nft_counters_enabled))
 249                 nft_update_chain_stats(basechain, pkt);
 250
 251         return nft_base_chain(basechain)->policy;
 252 }
 253 EXPORT_SYMBOL_GPL(nft_do_chain);
 254
 255 static struct nft_expr_type *nft_basic_types[] = {
 256         &nft_imm_type,
 257         &nft_cmp_type,
 258         &nft_lookup_type,
 259         &nft_bitwise_type,
 260         &nft_byteorder_type,
 261         &nft_payload_type,
 262         &nft_dynset_type,
 263         &nft_range_type,
 264 };
 265
 266 int __init nf_tables_core_module_init(void)
 267 {
 268         int err, i;
 269
 270         for (i = 0; i < ARRAY_SIZE(nft_basic_types); i++) {
 271                 err = nft_register_expr(nft_basic_types[i]);
 272                 if (err)
 273                         goto err;
 274         }
 275
 276         return 0;
 277
 278 err:
 279         while (i-- > 0)
 280                 nft_unregister_expr(nft_basic_types[i]);
 281         return err;
 282 }
 283
 284 void nf_tables_core_module_exit(void)
 285 {
 286         int i;
 287
 288         i = ARRAY_SIZE(nft_basic_types);
 289         while (i-- > 0)
 290                 nft_unregister_expr(nft_basic_types[i]);
 291 }