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_packet(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_data data[NFT_REG_MAX + 1])
  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 ((data[priv->sreg].data[0] & mask) == priv->data)
  74                 return;
  75         data[NFT_REG_VERDICT].verdict = NFT_BREAK;
  76 }
  77
  78 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  79                                   struct nft_data data[NFT_REG_MAX + 1],
  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         struct nft_data *dest = &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         if (priv->len == 2)
  98                 *(u16 *)dest->data = *(u16 *)ptr;
  99         else if (priv->len == 4)
 100                 *(u32 *)dest->data = *(u32 *)ptr;
 101         else
 102                 *(u8 *)dest->data = *(u8 *)ptr;
 103         return true;
 104 }
 105
 106 struct nft_jumpstack {
 107         const struct nft_chain  *chain;
 108         const struct nft_rule   *rule;
 109         int                     rulenum;
 110 };
 111
 112 unsigned int
 113 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 114 {
 115         const struct nft_chain *chain = ops->priv, *basechain = chain;
 116         const struct net *net = read_pnet(&nft_base_chain(basechain)->pnet);
 117         const struct nft_rule *rule;
 118         const struct nft_expr *expr, *last;
 119         struct nft_data data[NFT_REG_MAX + 1];
 120         unsigned int stackptr = 0;
 121         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 122         struct nft_stats *stats;
 123         int rulenum;
 124         /*
 125          * Cache cursor to avoid problems in case that the cursor is updated
 126          * while traversing the ruleset.
 127          */
 128         unsigned int gencursor = ACCESS_ONCE(net->nft.gencursor);
 129
 130 do_chain:
 131         rulenum = 0;
 132         rule = list_entry(&chain->rules, struct nft_rule, list);
 133 next_rule:
 134         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 135         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 136
 137                 /* This rule is not active, skip. */
 138                 if (unlikely(rule->genmask & (1 << gencursor)))
 139                         continue;
 140
 141                 rulenum++;
 142
 143                 nft_rule_for_each_expr(expr, last, rule) {
 144                         if (expr->ops == &nft_cmp_fast_ops)
 145                                 nft_cmp_fast_eval(expr, data);
 146                         else if (expr->ops != &nft_payload_fast_ops ||
 147                                  !nft_payload_fast_eval(expr, data, pkt))
 148                                 expr->ops->eval(expr, data, pkt);
 149
 150                         if (data[NFT_REG_VERDICT].verdict != NFT_CONTINUE)
 151                                 break;
 152                 }
 153
 154                 switch (data[NFT_REG_VERDICT].verdict) {
 155                 case NFT_BREAK:
 156                         data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
 157                         continue;
 158                 case NFT_CONTINUE:
 159                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 160                         continue;
 161                 }
 162                 break;
 163         }
 164
 165         switch (data[NFT_REG_VERDICT].verdict & NF_VERDICT_MASK) {
 166         case NF_ACCEPT:
 167         case NF_DROP:
 168         case NF_QUEUE:
 169                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 170                 return data[NFT_REG_VERDICT].verdict;
 171         }
 172
 173         switch (data[NFT_REG_VERDICT].verdict) {
 174         case NFT_JUMP:
 175                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 176                 jumpstack[stackptr].chain = chain;
 177                 jumpstack[stackptr].rule  = rule;
 178                 jumpstack[stackptr].rulenum = rulenum;
 179                 stackptr++;
 180                 /* fall through */
 181         case NFT_GOTO:
 182                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 183
 184                 chain = data[NFT_REG_VERDICT].chain;
 185                 goto do_chain;
 186         case NFT_CONTINUE:
 187                 rulenum++;
 188                 /* fall through */
 189         case NFT_RETURN:
 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         nft_trace_packet(pkt, basechain, -1, NFT_TRACE_POLICY);
 205
 206         rcu_read_lock_bh();
 207         stats = this_cpu_ptr(rcu_dereference(nft_base_chain(basechain)->stats));
 208         u64_stats_update_begin(&stats->syncp);
 209         stats->pkts++;
 210         stats->bytes += pkt->skb->len;
 211         u64_stats_update_end(&stats->syncp);
 212         rcu_read_unlock_bh();
 213
 214         return nft_base_chain(basechain)->policy;
 215 }
 216 EXPORT_SYMBOL_GPL(nft_do_chain);
 217
 218 int __init nf_tables_core_module_init(void)
 219 {
 220         int err;
 221
 222         err = nft_immediate_module_init();
 223         if (err < 0)
 224                 goto err1;
 225
 226         err = nft_cmp_module_init();
 227         if (err < 0)
 228                 goto err2;
 229
 230         err = nft_lookup_module_init();
 231         if (err < 0)
 232                 goto err3;
 233
 234         err = nft_bitwise_module_init();
 235         if (err < 0)
 236                 goto err4;
 237
 238         err = nft_byteorder_module_init();
 239         if (err < 0)
 240                 goto err5;
 241
 242         err = nft_payload_module_init();
 243         if (err < 0)
 244                 goto err6;
 245
 246         return 0;
 247
 248 err6:
 249         nft_byteorder_module_exit();
 250 err5:
 251         nft_bitwise_module_exit();
 252 err4:
 253         nft_lookup_module_exit();
 254 err3:
 255         nft_cmp_module_exit();
 256 err2:
 257         nft_immediate_module_exit();
 258 err1:
 259         return err;
 260 }
 261
 262 void nf_tables_core_module_exit(void)
 263 {
 264         nft_payload_module_exit();
 265         nft_byteorder_module_exit();
 266         nft_bitwise_module_exit();
 267         nft_lookup_module_exit();
 268         nft_cmp_module_exit();
 269         nft_immediate_module_exit();
 270 }