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;
  29
  30         mask = ~0U >> (sizeof(priv->data) * BITS_PER_BYTE - priv->len);
  31         if ((data[priv->sreg].data[0] & mask) == priv->data)
  32                 return;
  33         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  34 }
  35
  36 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  37                                   struct nft_data data[NFT_REG_MAX + 1],
  38                                   const struct nft_pktinfo *pkt)
  39 {
  40         const struct nft_payload *priv = nft_expr_priv(expr);
  41         const struct sk_buff *skb = pkt->skb;
  42         struct nft_data *dest = &data[priv->dreg];
  43         unsigned char *ptr;
  44
  45         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  46                 ptr = skb_network_header(skb);
  47         else
  48                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  49
  50         ptr += priv->offset;
  51
  52         if (unlikely(ptr + priv->len >= skb_tail_pointer(skb)))
  53                 return false;
  54
  55         if (priv->len == 2)
  56                 *(u16 *)dest->data = *(u16 *)ptr;
  57         else if (priv->len == 4)
  58                 *(u32 *)dest->data = *(u32 *)ptr;
  59         else
  60                 *(u8 *)dest->data = *(u8 *)ptr;
  61         return true;
  62 }
  63
  64 struct nft_jumpstack {
  65         const struct nft_chain  *chain;
  66         const struct nft_rule   *rule;
  67         int                     rulenum;
  68 };
  69
  70 static inline void
  71 nft_chain_stats(const struct nft_chain *this, const struct nft_pktinfo *pkt,
  72                 struct nft_jumpstack *jumpstack, unsigned int stackptr)
  73 {
  74         struct nft_stats __percpu *stats;
  75         const struct nft_chain *chain = stackptr ? jumpstack[0].chain : this;
  76
  77         rcu_read_lock_bh();
  78         stats = rcu_dereference(nft_base_chain(chain)->stats);
  79         __this_cpu_inc(stats->pkts);
  80         __this_cpu_add(stats->bytes, pkt->skb->len);
  81         rcu_read_unlock_bh();
  82 }
  83
  84 enum nft_trace {
  85         NFT_TRACE_RULE,
  86         NFT_TRACE_RETURN,
  87         NFT_TRACE_POLICY,
  88 };
  89
  90 static const char *const comments[] = {
  91         [NFT_TRACE_RULE]        = "rule",
  92         [NFT_TRACE_RETURN]      = "return",
  93         [NFT_TRACE_POLICY]      = "policy",
  94 };
  95
  96 static struct nf_loginfo trace_loginfo = {
  97         .type = NF_LOG_TYPE_LOG,
  98         .u = {
  99                 .log = {
 100                         .level = 4,
 101                         .logflags = NF_LOG_MASK,
 102                 },
 103         },
 104 };
 105
 106 static void nft_trace_packet(const struct nft_pktinfo *pkt,
 107                              const struct nft_chain *chain,
 108                              int rulenum, enum nft_trace type)
 109 {
 110         struct net *net = dev_net(pkt->in ? pkt->in : pkt->out);
 111
 112         nf_log_packet(net, pkt->xt.family, pkt->ops->hooknum, pkt->skb, pkt->in,
 113                       pkt->out, &trace_loginfo, "TRACE: %s:%s:%s:%u ",
 114                       chain->table->name, chain->name, comments[type],
 115                       rulenum);
 116 }
 117
 118 unsigned int
 119 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 120 {
 121         const struct nft_chain *chain = ops->priv;
 122         const struct nft_rule *rule;
 123         const struct nft_expr *expr, *last;
 124         struct nft_data data[NFT_REG_MAX + 1];
 125         unsigned int stackptr = 0;
 126         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 127         int rulenum = 0;
 128         /*
 129          * Cache cursor to avoid problems in case that the cursor is updated
 130          * while traversing the ruleset.
 131          */
 132         unsigned int gencursor = ACCESS_ONCE(chain->net->nft.gencursor);
 133
 134 do_chain:
 135         rule = list_entry(&chain->rules, struct nft_rule, list);
 136 next_rule:
 137         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 138         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 139
 140                 /* This rule is not active, skip. */
 141                 if (unlikely(rule->genmask & (1 << gencursor)))
 142                         continue;
 143
 144                 rulenum++;
 145
 146                 nft_rule_for_each_expr(expr, last, rule) {
 147                         if (expr->ops == &nft_cmp_fast_ops)
 148                                 nft_cmp_fast_eval(expr, data);
 149                         else if (expr->ops != &nft_payload_fast_ops ||
 150                                  !nft_payload_fast_eval(expr, data, pkt))
 151                                 expr->ops->eval(expr, data, pkt);
 152
 153                         if (data[NFT_REG_VERDICT].verdict != NFT_CONTINUE)
 154                                 break;
 155                 }
 156
 157                 switch (data[NFT_REG_VERDICT].verdict) {
 158                 case NFT_BREAK:
 159                         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 160                         /* fall through */
 161                 case NFT_CONTINUE:
 162                         continue;
 163                 }
 164                 break;
 165         }
 166
 167         switch (data[NFT_REG_VERDICT].verdict & NF_VERDICT_MASK) {
 168         case NF_ACCEPT:
 169         case NF_DROP:
 170         case NF_QUEUE:
 171                 if (unlikely(pkt->skb->nf_trace))
 172                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 173
 174                 return data[NFT_REG_VERDICT].verdict;
 175         }
 176
 177         switch (data[NFT_REG_VERDICT].verdict) {
 178         case NFT_JUMP:
 179                 if (unlikely(pkt->skb->nf_trace))
 180                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 181
 182                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 183                 jumpstack[stackptr].chain = chain;
 184                 jumpstack[stackptr].rule  = rule;
 185                 jumpstack[stackptr].rulenum = rulenum;
 186                 stackptr++;
 187                 /* fall through */
 188         case NFT_GOTO:
 189                 chain = data[NFT_REG_VERDICT].chain;
 190                 goto do_chain;
 191         case NFT_RETURN:
 192                 if (unlikely(pkt->skb->nf_trace))
 193                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RETURN);
 194
 195                 /* fall through */
 196         case NFT_CONTINUE:
 197                 break;
 198         default:
 199                 WARN_ON(1);
 200         }
 201
 202         if (stackptr > 0) {
 203                 if (unlikely(pkt->skb->nf_trace))
 204                         nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_RETURN);
 205
 206                 stackptr--;
 207                 chain = jumpstack[stackptr].chain;
 208                 rule  = jumpstack[stackptr].rule;
 209                 rulenum = jumpstack[stackptr].rulenum;
 210                 goto next_rule;
 211         }
 212         nft_chain_stats(chain, pkt, jumpstack, stackptr);
 213
 214         if (unlikely(pkt->skb->nf_trace))
 215                 nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_POLICY);
 216
 217         return nft_base_chain(chain)->policy;
 218 }
 219 EXPORT_SYMBOL_GPL(nft_do_chain);
 220
 221 int __init nf_tables_core_module_init(void)
 222 {
 223         int err;
 224
 225         err = nft_immediate_module_init();
 226         if (err < 0)
 227                 goto err1;
 228
 229         err = nft_cmp_module_init();
 230         if (err < 0)
 231                 goto err2;
 232
 233         err = nft_lookup_module_init();
 234         if (err < 0)
 235                 goto err3;
 236
 237         err = nft_bitwise_module_init();
 238         if (err < 0)
 239                 goto err4;
 240
 241         err = nft_byteorder_module_init();
 242         if (err < 0)
 243                 goto err5;
 244
 245         err = nft_payload_module_init();
 246         if (err < 0)
 247                 goto err6;
 248
 249         return 0;
 250
 251 err6:
 252         nft_byteorder_module_exit();
 253 err5:
 254         nft_bitwise_module_exit();
 255 err4:
 256         nft_lookup_module_exit();
 257 err3:
 258         nft_cmp_module_exit();
 259 err2:
 260         nft_immediate_module_exit();
 261 err1:
 262         return err;
 263 }
 264
 265 void nf_tables_core_module_exit(void)
 266 {
 267         nft_payload_module_exit();
 268         nft_byteorder_module_exit();
 269         nft_bitwise_module_exit();
 270         nft_lookup_module_exit();
 271         nft_cmp_module_exit();
 272         nft_immediate_module_exit();
 273 }