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 static inline void
  70 nft_chain_stats(const struct nft_chain *this, const struct nft_pktinfo *pkt,
  71                 struct nft_jumpstack *jumpstack, unsigned int stackptr)
  72 {
  73         struct nft_stats __percpu *stats;
  74         const struct nft_chain *chain = stackptr ? jumpstack[0].chain : this;
  75
  76         rcu_read_lock_bh();
  77         stats = rcu_dereference(nft_base_chain(chain)->stats);
  78         __this_cpu_inc(stats->pkts);
  79         __this_cpu_add(stats->bytes, pkt->skb->len);
  80         rcu_read_unlock_bh();
  81 }
  82
  83 enum nft_trace {
  84         NFT_TRACE_RULE,
  85         NFT_TRACE_RETURN,
  86         NFT_TRACE_POLICY,
  87 };
  88
  89 static const char *const comments[] = {
  90         [NFT_TRACE_RULE]        = "rule",
  91         [NFT_TRACE_RETURN]      = "return",
  92         [NFT_TRACE_POLICY]      = "policy",
  93 };
  94
  95 static struct nf_loginfo trace_loginfo = {
  96         .type = NF_LOG_TYPE_LOG,
  97         .u = {
  98                 .log = {
  99                         .level = 4,
 100                         .logflags = NF_LOG_MASK,
 101                 },
 102         },
 103 };
 104
 105 static void nft_trace_packet(const struct nft_pktinfo *pkt,
 106                              const struct nft_chain *chain,
 107                              int rulenum, enum nft_trace type)
 108 {
 109         struct net *net = dev_net(pkt->in ? pkt->in : pkt->out);
 110
 111         nf_log_packet(net, pkt->xt.family, pkt->ops->hooknum, pkt->skb, pkt->in,
 112                       pkt->out, &trace_loginfo, "TRACE: %s:%s:%s:%u ",
 113                       chain->table->name, chain->name, comments[type],
 114                       rulenum);
 115 }
 116
 117 unsigned int
 118 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 119 {
 120         const struct nft_chain *chain = ops->priv;
 121         const struct nft_rule *rule;
 122         const struct nft_expr *expr, *last;
 123         struct nft_data data[NFT_REG_MAX + 1];
 124         unsigned int stackptr = 0;
 125         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 126         int rulenum;
 127         /*
 128          * Cache cursor to avoid problems in case that the cursor is updated
 129          * while traversing the ruleset.
 130          */
 131         unsigned int gencursor = ACCESS_ONCE(chain->net->nft.gencursor);
 132
 133 do_chain:
 134         rulenum = 0;
 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 }