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