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/static_key.h>
  20 #include <linux/netfilter/nfnetlink.h>
  21 #include <linux/netfilter/nf_tables.h>
  22 #include <net/netfilter/nf_tables_core.h>
  23 #include <net/netfilter/nf_tables.h>
  24 #include <net/netfilter/nf_log.h>
  25
  26 static const char *const comments[__NFT_TRACETYPE_MAX] = {
  27         [NFT_TRACETYPE_POLICY]  = "policy",
  28         [NFT_TRACETYPE_RETURN]  = "return",
  29         [NFT_TRACETYPE_RULE]    = "rule",
  30 };
  31
  32 static const struct nf_loginfo trace_loginfo = {
  33         .type = NF_LOG_TYPE_LOG,
  34         .u = {
  35                 .log = {
  36                         .level = LOGLEVEL_WARNING,
  37                         .logflags = NF_LOG_DEFAULT_MASK,
  38                 },
  39         },
  40 };
  41
  42 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
  43                                         const struct nft_chain *chain,
  44                                         int rulenum, enum nft_trace_types type)
  45 {
  46         const struct nft_pktinfo *pkt = info->pkt;
  47
  48         if (!info->trace || !pkt->skb->nf_trace)
  49                 return;
  50
  51         info->chain = chain;
  52         info->type = type;
  53
  54         nft_trace_notify(info);
  55
  56         nf_log_trace(nft_net(pkt), nft_pf(pkt), nft_hook(pkt), pkt->skb,
  57                      nft_in(pkt), nft_out(pkt), &trace_loginfo,
  58                      "TRACE: %s:%s:%s:%u ",
  59                      chain->table->name, chain->name, comments[type], rulenum);
  60 }
  61
  62 static inline void nft_trace_packet(struct nft_traceinfo *info,
  63                                     const struct nft_chain *chain,
  64                                     const struct nft_rule *rule,
  65                                     int rulenum,
  66                                     enum nft_trace_types type)
  67 {
  68         if (static_branch_unlikely(&nft_trace_enabled)) {
  69                 info->rule = rule;
  70                 __nft_trace_packet(info, chain, rulenum, type);
  71         }
  72 }
  73
  74 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  75                               struct nft_regs *regs)
  76 {
  77         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  78         u32 mask = nft_cmp_fast_mask(priv->len);
  79
  80         if ((regs->data[priv->sreg] & mask) == priv->data)
  81                 return;
  82         regs->verdict.code = NFT_BREAK;
  83 }
  84
  85 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  86                                   struct nft_regs *regs,
  87                                   const struct nft_pktinfo *pkt)
  88 {
  89         const struct nft_payload *priv = nft_expr_priv(expr);
  90         const struct sk_buff *skb = pkt->skb;
  91         u32 *dest = &regs->data[priv->dreg];
  92         unsigned char *ptr;
  93
  94         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  95                 ptr = skb_network_header(skb);
  96         else {
  97                 if (!pkt->tprot_set)
  98                         return false;
  99                 ptr = skb_network_header(skb) + pkt->xt.thoff;
 100         }
 101
 102         ptr += priv->offset;
 103
 104         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
 105                 return false;
 106
 107         *dest = 0;
 108         if (priv->len == 2)
 109                 *(u16 *)dest = *(u16 *)ptr;
 110         else if (priv->len == 4)
 111                 *(u32 *)dest = *(u32 *)ptr;
 112         else
 113                 *(u8 *)dest = *(u8 *)ptr;
 114         return true;
 115 }
 116
 117 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
 118
 119 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 120                                             const struct nft_pktinfo *pkt)
 121 {
 122         struct nft_base_chain *base_chain;
 123         struct nft_stats *stats;
 124
 125         base_chain = nft_base_chain(chain);
 126         if (!base_chain->stats)
 127                 return;
 128
 129         local_bh_disable();
 130         stats = this_cpu_ptr(rcu_dereference(base_chain->stats));
 131         if (stats) {
 132                 u64_stats_update_begin(&stats->syncp);
 133                 stats->pkts++;
 134                 stats->bytes += pkt->skb->len;
 135                 u64_stats_update_end(&stats->syncp);
 136         }
 137         local_bh_enable();
 138 }
 139
 140 struct nft_jumpstack {
 141         const struct nft_chain  *chain;
 142         const struct nft_rule   *rule;
 143         int                     rulenum;
 144 };
 145
 146 unsigned int
 147 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 148 {
 149         const struct nft_chain *chain = priv, *basechain = chain;
 150         const struct net *net = nft_net(pkt);
 151         const struct nft_rule *rule;
 152         const struct nft_expr *expr, *last;
 153         struct nft_regs regs = {};
 154         unsigned int stackptr = 0;
 155         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 156         int rulenum;
 157         unsigned int gencursor = nft_genmask_cur(net);
 158         struct nft_traceinfo info;
 159
 160         info.trace = false;
 161         if (static_branch_unlikely(&nft_trace_enabled))
 162                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 163 do_chain:
 164         rulenum = 0;
 165         rule = list_entry(&chain->rules, struct nft_rule, list);
 166 next_rule:
 167         regs.verdict.code = NFT_CONTINUE;
 168         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 169
 170                 /* This rule is not active, skip. */
 171                 if (unlikely(rule->genmask & gencursor))
 172                         continue;
 173
 174                 rulenum++;
 175
 176                 nft_rule_for_each_expr(expr, last, rule) {
 177                         if (expr->ops == &nft_cmp_fast_ops)
 178                                 nft_cmp_fast_eval(expr, &regs);
 179                         else if (expr->ops != &nft_payload_fast_ops ||
 180                                  !nft_payload_fast_eval(expr, &regs, pkt))
 181                                 expr->ops->eval(expr, &regs, pkt);
 182
 183                         if (regs.verdict.code != NFT_CONTINUE)
 184                                 break;
 185                 }
 186
 187                 switch (regs.verdict.code) {
 188                 case NFT_BREAK:
 189                         regs.verdict.code = NFT_CONTINUE;
 190                         continue;
 191                 case NFT_CONTINUE:
 192                         nft_trace_packet(&info, chain, rule,
 193                                          rulenum, NFT_TRACETYPE_RULE);
 194                         continue;
 195                 }
 196                 break;
 197         }
 198
 199         switch (regs.verdict.code & NF_VERDICT_MASK) {
 200         case NF_ACCEPT:
 201         case NF_DROP:
 202         case NF_QUEUE:
 203         case NF_STOLEN:
 204                 nft_trace_packet(&info, chain, rule,
 205                                  rulenum, NFT_TRACETYPE_RULE);
 206                 return regs.verdict.code;
 207         }
 208
 209         switch (regs.verdict.code) {
 210         case NFT_JUMP:
 211                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 212                         return NF_DROP;
 213                 jumpstack[stackptr].chain = chain;
 214                 jumpstack[stackptr].rule  = rule;
 215                 jumpstack[stackptr].rulenum = rulenum;
 216                 stackptr++;
 217                 /* fall through */
 218         case NFT_GOTO:
 219                 nft_trace_packet(&info, chain, rule,
 220                                  rulenum, NFT_TRACETYPE_RULE);
 221
 222                 chain = regs.verdict.chain;
 223                 goto do_chain;
 224         case NFT_CONTINUE:
 225                 rulenum++;
 226                 /* fall through */
 227         case NFT_RETURN:
 228                 nft_trace_packet(&info, chain, rule,
 229                                  rulenum, NFT_TRACETYPE_RETURN);
 230                 break;
 231         default:
 232                 WARN_ON(1);
 233         }
 234
 235         if (stackptr > 0) {
 236                 stackptr--;
 237                 chain = jumpstack[stackptr].chain;
 238                 rule  = jumpstack[stackptr].rule;
 239                 rulenum = jumpstack[stackptr].rulenum;
 240                 goto next_rule;
 241         }
 242
 243         nft_trace_packet(&info, basechain, NULL, -1,
 244                          NFT_TRACETYPE_POLICY);
 245
 246         if (static_branch_unlikely(&nft_counters_enabled))
 247                 nft_update_chain_stats(basechain, pkt);
 248
 249         return nft_base_chain(basechain)->policy;
 250 }
 251 EXPORT_SYMBOL_GPL(nft_do_chain);
 252
 253 static struct nft_expr_type *nft_basic_types[] = {
 254         &nft_imm_type,
 255         &nft_cmp_type,
 256         &nft_lookup_type,
 257         &nft_bitwise_type,
 258         &nft_byteorder_type,
 259         &nft_payload_type,
 260         &nft_dynset_type,
 261         &nft_range_type,
 262 };
 263
 264 int __init nf_tables_core_module_init(void)
 265 {
 266         int err, i;
 267
 268         for (i = 0; i < ARRAY_SIZE(nft_basic_types); i++) {
 269                 err = nft_register_expr(nft_basic_types[i]);
 270                 if (err)
 271                         goto err;
 272         }
 273
 274         return 0;
 275
 276 err:
 277         while (i-- > 0)
 278                 nft_unregister_expr(nft_basic_types[i]);
 279         return err;
 280 }
 281
 282 void nf_tables_core_module_exit(void)
 283 {
 284         int i;
 285
 286         i = ARRAY_SIZE(nft_basic_types);
 287         while (i-- > 0)
 288                 nft_unregister_expr(nft_basic_types[i]);
 289 }