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/module.h>
  12 #include <linux/init.h>
  13 #include <linux/list.h>
  14 #include <linux/rculist.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/netlink.h>
  17 #include <linux/netfilter.h>
  18 #include <linux/netfilter/nfnetlink.h>
  19 #include <linux/netfilter/nf_tables.h>
  20 #include <net/netfilter/nf_tables_core.h>
  21 #include <net/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_log.h>
  23
  24 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  25                               struct nft_data data[NFT_REG_MAX + 1])
  26 {
  27         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  28         u32 mask = nft_cmp_fast_mask(priv->len);
  29
  30         if ((data[priv->sreg].data[0] & mask) == priv->data)
  31                 return;
  32         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  33 }
  34
  35 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  36                                   struct nft_data data[NFT_REG_MAX + 1],
  37                                   const struct nft_pktinfo *pkt)
  38 {
  39         const struct nft_payload *priv = nft_expr_priv(expr);
  40         const struct sk_buff *skb = pkt->skb;
  41         struct nft_data *dest = &data[priv->dreg];
  42         unsigned char *ptr;
  43
  44         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  45                 ptr = skb_network_header(skb);
  46         else
  47                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  48
  49         ptr += priv->offset;
  50
  51         if (unlikely(ptr + priv->len >= skb_tail_pointer(skb)))
  52                 return false;
  53
  54         if (priv->len == 2)
  55                 *(u16 *)dest->data = *(u16 *)ptr;
  56         else if (priv->len == 4)
  57                 *(u32 *)dest->data = *(u32 *)ptr;
  58         else
  59                 *(u8 *)dest->data = *(u8 *)ptr;
  60         return true;
  61 }
  62
  63 struct nft_jumpstack {
  64         const struct nft_chain  *chain;
  65         const struct nft_rule   *rule;
  66         int                     rulenum;
  67 };
  68
  69 enum nft_trace {
  70         NFT_TRACE_RULE,
  71         NFT_TRACE_RETURN,
  72         NFT_TRACE_POLICY,
  73 };
  74
  75 static const char *const comments[] = {
  76         [NFT_TRACE_RULE]        = "rule",
  77         [NFT_TRACE_RETURN]      = "return",
  78         [NFT_TRACE_POLICY]      = "policy",
  79 };
  80
  81 static struct nf_loginfo trace_loginfo = {
  82         .type = NF_LOG_TYPE_LOG,
  83         .u = {
  84                 .log = {
  85                         .level = 4,
  86                         .logflags = NF_LOG_MASK,
  87                 },
  88         },
  89 };
  90
  91 static void nft_trace_packet(const struct nft_pktinfo *pkt,
  92                              const struct nft_chain *chain,
  93                              int rulenum, enum nft_trace type)
  94 {
  95         struct net *net = dev_net(pkt->in ? pkt->in : pkt->out);
  96
  97         nf_log_packet(net, pkt->xt.family, pkt->ops->hooknum, pkt->skb, pkt->in,
  98                       pkt->out, &trace_loginfo, "TRACE: %s:%s:%s:%u ",
  99                       chain->table->name, chain->name, comments[type],
 100                       rulenum);
 101 }
 102
 103 unsigned int
 104 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 105 {
 106         const struct nft_chain *chain = ops->priv, *basechain = chain;
 107         const struct nft_rule *rule;
 108         const struct nft_expr *expr, *last;
 109         struct nft_data data[NFT_REG_MAX + 1];
 110         unsigned int stackptr = 0;
 111         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 112         struct nft_stats *stats;
 113         int rulenum;
 114         /*
 115          * Cache cursor to avoid problems in case that the cursor is updated
 116          * while traversing the ruleset.
 117          */
 118         unsigned int gencursor = ACCESS_ONCE(chain->net->nft.gencursor);
 119
 120 do_chain:
 121         rulenum = 0;
 122         rule = list_entry(&chain->rules, struct nft_rule, list);
 123 next_rule:
 124         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 125         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 126
 127                 /* This rule is not active, skip. */
 128                 if (unlikely(rule->genmask & (1 << gencursor)))
 129                         continue;
 130
 131                 rulenum++;
 132
 133                 nft_rule_for_each_expr(expr, last, rule) {
 134                         if (expr->ops == &nft_cmp_fast_ops)
 135                                 nft_cmp_fast_eval(expr, data);
 136                         else if (expr->ops != &nft_payload_fast_ops ||
 137                                  !nft_payload_fast_eval(expr, data, pkt))
 138                                 expr->ops->eval(expr, data, pkt);
 139
 140                         if (data[NFT_REG_VERDICT].verdict != NFT_CONTINUE)
 141                                 break;
 142                 }
 143
 144                 switch (data[NFT_REG_VERDICT].verdict) {
 145                 case NFT_BREAK:
 146                         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 147                         continue;
 148                 case NFT_CONTINUE:
 149                         if (unlikely(pkt->skb->nf_trace))
 150                                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 151                         continue;
 152                 }
 153                 break;
 154         }
 155
 156         switch (data[NFT_REG_VERDICT].verdict & NF_VERDICT_MASK) {
 157         case NF_ACCEPT:
 158         case NF_DROP:
 159         case NF_QUEUE:
 160                 if (unlikely(pkt->skb->nf_trace))
 161                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 162
 163                 return data[NFT_REG_VERDICT].verdict;
 164         }
 165
 166         switch (data[NFT_REG_VERDICT].verdict) {
 167         case NFT_JUMP:
 168                 if (unlikely(pkt->skb->nf_trace))
 169                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 170
 171                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 172                 jumpstack[stackptr].chain = chain;
 173                 jumpstack[stackptr].rule  = rule;
 174                 jumpstack[stackptr].rulenum = rulenum;
 175                 stackptr++;
 176                 chain = data[NFT_REG_VERDICT].chain;
 177                 goto do_chain;
 178         case NFT_GOTO:
 179                 if (unlikely(pkt->skb->nf_trace))
 180                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 181
 182                 chain = data[NFT_REG_VERDICT].chain;
 183                 goto do_chain;
 184         case NFT_RETURN:
 185                 if (unlikely(pkt->skb->nf_trace))
 186                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RETURN);
 187                 break;
 188         case NFT_CONTINUE:
 189                 if (unlikely(pkt->skb->nf_trace && !(chain->flags & NFT_BASE_CHAIN)))
 190                         nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_RETURN);
 191                 break;
 192         default:
 193                 WARN_ON(1);
 194         }
 195
 196         if (stackptr > 0) {
 197                 stackptr--;
 198                 chain = jumpstack[stackptr].chain;
 199                 rule  = jumpstack[stackptr].rule;
 200                 rulenum = jumpstack[stackptr].rulenum;
 201                 goto next_rule;
 202         }
 203
 204         if (unlikely(pkt->skb->nf_trace))
 205                 nft_trace_packet(pkt, basechain, -1, NFT_TRACE_POLICY);
 206
 207         rcu_read_lock_bh();
 208         stats = this_cpu_ptr(rcu_dereference(nft_base_chain(basechain)->stats));
 209         u64_stats_update_begin(&stats->syncp);
 210         stats->pkts++;
 211         stats->bytes += pkt->skb->len;
 212         u64_stats_update_end(&stats->syncp);
 213         rcu_read_unlock_bh();
 214
 215         return nft_base_chain(basechain)->policy;
 216 }
 217 EXPORT_SYMBOL_GPL(nft_do_chain);
 218
 219 int __init nf_tables_core_module_init(void)
 220 {
 221         int err;
 222
 223         err = nft_immediate_module_init();
 224         if (err < 0)
 225                 goto err1;
 226
 227         err = nft_cmp_module_init();
 228         if (err < 0)
 229                 goto err2;
 230
 231         err = nft_lookup_module_init();
 232         if (err < 0)
 233                 goto err3;
 234
 235         err = nft_bitwise_module_init();
 236         if (err < 0)
 237                 goto err4;
 238
 239         err = nft_byteorder_module_init();
 240         if (err < 0)
 241                 goto err5;
 242
 243         err = nft_payload_module_init();
 244         if (err < 0)
 245                 goto err6;
 246
 247         return 0;
 248
 249 err6:
 250         nft_byteorder_module_exit();
 251 err5:
 252         nft_bitwise_module_exit();
 253 err4:
 254         nft_lookup_module_exit();
 255 err3:
 256         nft_cmp_module_exit();
 257 err2:
 258         nft_immediate_module_exit();
 259 err1:
 260         return err;
 261 }
 262
 263 void nf_tables_core_module_exit(void)
 264 {
 265         nft_payload_module_exit();
 266         nft_byteorder_module_exit();
 267         nft_bitwise_module_exit();
 268         nft_lookup_module_exit();
 269         nft_cmp_module_exit();
 270         nft_immediate_module_exit();
 271 }