kernel/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/netfilter/nfnetlink.h>
  20 #include <linux/netfilter/nf_tables.h>
  21 #include <net/netfilter/nf_tables_core.h>
  22 #include <net/netfilter/nf_tables.h>
  23 #include <net/netfilter/nf_log.h>
  24
  25 enum nft_trace {
  26         NFT_TRACE_RULE,
  27         NFT_TRACE_RETURN,
  28         NFT_TRACE_POLICY,
  29 };
  30
  31 static const char *const comments[] = {
  32         [NFT_TRACE_RULE]        = "rule",
  33         [NFT_TRACE_RETURN]      = "return",
  34         [NFT_TRACE_POLICY]      = "policy",
  35 };
  36
  37 static struct nf_loginfo trace_loginfo = {
  38         .type = NF_LOG_TYPE_LOG,
  39         .u = {
  40                 .log = {
  41                         .level = LOGLEVEL_WARNING,
  42                         .logflags = NF_LOG_MASK,
  43                 },
  44         },
  45 };
  46
  47 static void __nft_trace_packet(const struct nft_pktinfo *pkt,
  48                                const struct nft_chain *chain,
  49                                int rulenum, enum nft_trace type)
  50 {
  51         struct net *net = dev_net(pkt->in ? pkt->in : pkt->out);
  52
  53         nf_log_trace(net, pkt->xt.family, pkt->ops->hooknum, pkt->skb, pkt->in,
  54                      pkt->out, &trace_loginfo, "TRACE: %s:%s:%s:%u ",
  55                      chain->table->name, chain->name, comments[type],
  56                      rulenum);
  57 }
  58
  59 static inline void nft_trace_packet(const struct nft_pktinfo *pkt,
  60                                     const struct nft_chain *chain,
  61                                     int rulenum, enum nft_trace type)
  62 {
  63         if (unlikely(pkt->skb->nf_trace))
  64                 __nft_trace_packet(pkt, chain, rulenum, type);
  65 }
  66
  67 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  68                               struct nft_regs *regs)
  69 {
  70         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  71         u32 mask = nft_cmp_fast_mask(priv->len);
  72
  73         if ((regs->data[priv->sreg] & mask) == priv->data)
  74                 return;
  75         regs->verdict.code = NFT_BREAK;
  76 }
  77
  78 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  79                                   struct nft_regs *regs,
  80                                   const struct nft_pktinfo *pkt)
  81 {
  82         const struct nft_payload *priv = nft_expr_priv(expr);
  83         const struct sk_buff *skb = pkt->skb;
  84         u32 *dest = &regs->data[priv->dreg];
  85         unsigned char *ptr;
  86
  87         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  88                 ptr = skb_network_header(skb);
  89         else
  90                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  91
  92         ptr += priv->offset;
  93
  94         if (unlikely(ptr + priv->len >= skb_tail_pointer(skb)))
  95                 return false;
  96
  97         *dest = 0;
  98         if (priv->len == 2)
  99                 *(u16 *)dest = *(u16 *)ptr;
 100         else if (priv->len == 4)
 101                 *(u32 *)dest = *(u32 *)ptr;
 102         else
 103                 *(u8 *)dest = *(u8 *)ptr;
 104         return true;
 105 }
 106
 107 struct nft_jumpstack {
 108         const struct nft_chain  *chain;
 109         const struct nft_rule   *rule;
 110         int                     rulenum;
 111 };
 112
 113 unsigned int
 114 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 115 {
 116         const struct nft_chain *chain = ops->priv, *basechain = chain;
 117         const struct net *net = read_pnet(&nft_base_chain(basechain)->pnet);
 118         const struct nft_rule *rule;
 119         const struct nft_expr *expr, *last;
 120         struct nft_regs regs;
 121         unsigned int stackptr = 0;
 122         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 123         struct nft_stats *stats;
 124         int rulenum;
 125         unsigned int gencursor = nft_genmask_cur(net);
 126
 127 do_chain:
 128         rulenum = 0;
 129         rule = list_entry(&chain->rules, struct nft_rule, list);
 130 next_rule:
 131         regs.verdict.code = NFT_CONTINUE;
 132         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 133
 134                 /* This rule is not active, skip. */
 135                 if (unlikely(rule->genmask & (1 << gencursor)))
 136                         continue;
 137
 138                 rulenum++;
 139
 140                 nft_rule_for_each_expr(expr, last, rule) {
 141                         if (expr->ops == &nft_cmp_fast_ops)
 142                                 nft_cmp_fast_eval(expr, &regs);
 143                         else if (expr->ops != &nft_payload_fast_ops ||
 144                                  !nft_payload_fast_eval(expr, &regs, pkt))
 145                                 expr->ops->eval(expr, &regs, pkt);
 146
 147                         if (regs.verdict.code != NFT_CONTINUE)
 148                                 break;
 149                 }
 150
 151                 switch (regs.verdict.code) {
 152                 case NFT_BREAK:
 153                         regs.verdict.code = NFT_CONTINUE;
 154                         continue;
 155                 case NFT_CONTINUE:
 156                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 157                         continue;
 158                 }
 159                 break;
 160         }
 161
 162         switch (regs.verdict.code & NF_VERDICT_MASK) {
 163         case NF_ACCEPT:
 164         case NF_DROP:
 165         case NF_QUEUE:
 166                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 167                 return regs.verdict.code;
 168         }
 169
 170         switch (regs.verdict.code) {
 171         case NFT_JUMP:
 172                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 173                 jumpstack[stackptr].chain = chain;
 174                 jumpstack[stackptr].rule  = rule;
 175                 jumpstack[stackptr].rulenum = rulenum;
 176                 stackptr++;
 177                 /* fall through */
 178         case NFT_GOTO:
 179                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 180
 181                 chain = regs.verdict.chain;
 182                 goto do_chain;
 183         case NFT_CONTINUE:
 184                 rulenum++;
 185                 /* fall through */
 186         case NFT_RETURN:
 187                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RETURN);
 188                 break;
 189         default:
 190                 WARN_ON(1);
 191         }
 192
 193         if (stackptr > 0) {
 194                 stackptr--;
 195                 chain = jumpstack[stackptr].chain;
 196                 rule  = jumpstack[stackptr].rule;
 197                 rulenum = jumpstack[stackptr].rulenum;
 198                 goto next_rule;
 199         }
 200
 201         nft_trace_packet(pkt, basechain, -1, NFT_TRACE_POLICY);
 202
 203         rcu_read_lock_bh();
 204         stats = this_cpu_ptr(rcu_dereference(nft_base_chain(basechain)->stats));
 205         u64_stats_update_begin(&stats->syncp);
 206         stats->pkts++;
 207         stats->bytes += pkt->skb->len;
 208         u64_stats_update_end(&stats->syncp);
 209         rcu_read_unlock_bh();
 210
 211         return nft_base_chain(basechain)->policy;
 212 }
 213 EXPORT_SYMBOL_GPL(nft_do_chain);
 214
 215 int __init nf_tables_core_module_init(void)
 216 {
 217         int err;
 218
 219         err = nft_immediate_module_init();
 220         if (err < 0)
 221                 goto err1;
 222
 223         err = nft_cmp_module_init();
 224         if (err < 0)
 225                 goto err2;
 226
 227         err = nft_lookup_module_init();
 228         if (err < 0)
 229                 goto err3;
 230
 231         err = nft_bitwise_module_init();
 232         if (err < 0)
 233                 goto err4;
 234
 235         err = nft_byteorder_module_init();
 236         if (err < 0)
 237                 goto err5;
 238
 239         err = nft_payload_module_init();
 240         if (err < 0)
 241                 goto err6;
 242
 243         err = nft_dynset_module_init();
 244         if (err < 0)
 245                 goto err7;
 246
 247         return 0;
 248
 249 err7:
 250         nft_payload_module_exit();
 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_dynset_module_exit();
 268         nft_payload_module_exit();
 269         nft_byteorder_module_exit();
 270         nft_bitwise_module_exit();
 271         nft_lookup_module_exit();
 272         nft_cmp_module_exit();
 273         nft_immediate_module_exit();
 274 }