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 noinline void __nft_trace_packet(struct nft_traceinfo *info,
  27                                         const struct nft_chain *chain,
  28                                         enum nft_trace_types type)
  29 {
  30         const struct nft_pktinfo *pkt = info->pkt;
  31
  32         if (!info->trace || !pkt->skb->nf_trace)
  33                 return;
  34
  35         info->chain = chain;
  36         info->type = type;
  37
  38         nft_trace_notify(info);
  39 }
  40
  41 static inline void nft_trace_packet(struct nft_traceinfo *info,
  42                                     const struct nft_chain *chain,
  43                                     const struct nft_rule *rule,
  44                                     enum nft_trace_types type)
  45 {
  46         if (static_branch_unlikely(&nft_trace_enabled)) {
  47                 info->rule = rule;
  48                 __nft_trace_packet(info, chain, type);
  49         }
  50 }
  51
  52 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  53                               struct nft_regs *regs)
  54 {
  55         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  56         u32 mask = nft_cmp_fast_mask(priv->len);
  57
  58         if ((regs->data[priv->sreg] & mask) == priv->data)
  59                 return;
  60         regs->verdict.code = NFT_BREAK;
  61 }
  62
  63 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  64                                   struct nft_regs *regs,
  65                                   const struct nft_pktinfo *pkt)
  66 {
  67         const struct nft_payload *priv = nft_expr_priv(expr);
  68         const struct sk_buff *skb = pkt->skb;
  69         u32 *dest = &regs->data[priv->dreg];
  70         unsigned char *ptr;
  71
  72         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  73                 ptr = skb_network_header(skb);
  74         else {
  75                 if (!pkt->tprot_set)
  76                         return false;
  77                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  78         }
  79
  80         ptr += priv->offset;
  81
  82         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
  83                 return false;
  84
  85         *dest = 0;
  86         if (priv->len == 2)
  87                 *(u16 *)dest = *(u16 *)ptr;
  88         else if (priv->len == 4)
  89                 *(u32 *)dest = *(u32 *)ptr;
  90         else
  91                 *(u8 *)dest = *(u8 *)ptr;
  92         return true;
  93 }
  94
  95 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
  96
  97 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
  98                                             const struct nft_pktinfo *pkt)
  99 {
 100         struct nft_base_chain *base_chain;
 101         struct nft_stats __percpu *pstats;
 102         struct nft_stats *stats;
 103
 104         base_chain = nft_base_chain(chain);
 105
 106         rcu_read_lock();
 107         pstats = READ_ONCE(base_chain->stats);
 108         if (pstats) {
 109                 local_bh_disable();
 110                 stats = this_cpu_ptr(pstats);
 111                 u64_stats_update_begin(&stats->syncp);
 112                 stats->pkts++;
 113                 stats->bytes += pkt->skb->len;
 114                 u64_stats_update_end(&stats->syncp);
 115                 local_bh_enable();
 116         }
 117         rcu_read_unlock();
 118 }
 119
 120 struct nft_jumpstack {
 121         const struct nft_chain  *chain;
 122         struct nft_rule *const *rules;
 123 };
 124
 125 static void expr_call_ops_eval(const struct nft_expr *expr,
 126                                struct nft_regs *regs,
 127                                struct nft_pktinfo *pkt)
 128 {
 129 #ifdef CONFIG_RETPOLINE
 130         unsigned long e = (unsigned long)expr->ops->eval;
 131 #define X(e, fun) \
 132         do { if ((e) == (unsigned long)(fun)) \
 133                 return fun(expr, regs, pkt); } while (0)
 134
 135         X(e, nft_payload_eval);
 136         X(e, nft_cmp_eval);
 137         X(e, nft_meta_get_eval);
 138         X(e, nft_lookup_eval);
 139         X(e, nft_range_eval);
 140         X(e, nft_immediate_eval);
 141         X(e, nft_byteorder_eval);
 142         X(e, nft_dynset_eval);
 143         X(e, nft_rt_get_eval);
 144         X(e, nft_bitwise_eval);
 145 #undef  X
 146 #endif /* CONFIG_RETPOLINE */
 147         expr->ops->eval(expr, regs, pkt);
 148 }
 149
 150 unsigned int
 151 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 152 {
 153         const struct nft_chain *chain = priv, *basechain = chain;
 154         const struct net *net = nft_net(pkt);
 155         struct nft_rule *const *rules;
 156         const struct nft_rule *rule;
 157         const struct nft_expr *expr, *last;
 158         struct nft_regs regs;
 159         unsigned int stackptr = 0;
 160         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 161         bool genbit = READ_ONCE(net->nft.gencursor);
 162         struct nft_traceinfo info;
 163
 164         info.trace = false;
 165         if (static_branch_unlikely(&nft_trace_enabled))
 166                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 167 do_chain:
 168         if (genbit)
 169                 rules = rcu_dereference(chain->rules_gen_1);
 170         else
 171                 rules = rcu_dereference(chain->rules_gen_0);
 172
 173 next_rule:
 174         rule = *rules;
 175         regs.verdict.code = NFT_CONTINUE;
 176         for (; *rules ; rules++) {
 177                 rule = *rules;
 178                 nft_rule_for_each_expr(expr, last, rule) {
 179                         if (expr->ops == &nft_cmp_fast_ops)
 180                                 nft_cmp_fast_eval(expr, &regs);
 181                         else if (expr->ops != &nft_payload_fast_ops ||
 182                                  !nft_payload_fast_eval(expr, &regs, pkt))
 183                                 expr_call_ops_eval(expr, &regs, pkt);
 184
 185                         if (regs.verdict.code != NFT_CONTINUE)
 186                                 break;
 187                 }
 188
 189                 switch (regs.verdict.code) {
 190                 case NFT_BREAK:
 191                         regs.verdict.code = NFT_CONTINUE;
 192                         continue;
 193                 case NFT_CONTINUE:
 194                         nft_trace_packet(&info, chain, rule,
 195                                          NFT_TRACETYPE_RULE);
 196                         continue;
 197                 }
 198                 break;
 199         }
 200
 201         switch (regs.verdict.code & NF_VERDICT_MASK) {
 202         case NF_ACCEPT:
 203         case NF_DROP:
 204         case NF_QUEUE:
 205         case NF_STOLEN:
 206                 nft_trace_packet(&info, chain, rule,
 207                                  NFT_TRACETYPE_RULE);
 208                 return regs.verdict.code;
 209         }
 210
 211         switch (regs.verdict.code) {
 212         case NFT_JUMP:
 213                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 214                         return NF_DROP;
 215                 jumpstack[stackptr].chain = chain;
 216                 jumpstack[stackptr].rules = rules + 1;
 217                 stackptr++;
 218                 /* fall through */
 219         case NFT_GOTO:
 220                 nft_trace_packet(&info, chain, rule,
 221                                  NFT_TRACETYPE_RULE);
 222
 223                 chain = regs.verdict.chain;
 224                 goto do_chain;
 225         case NFT_CONTINUE:
 226         case NFT_RETURN:
 227                 nft_trace_packet(&info, chain, rule,
 228                                  NFT_TRACETYPE_RETURN);
 229                 break;
 230         default:
 231                 WARN_ON(1);
 232         }
 233
 234         if (stackptr > 0) {
 235                 stackptr--;
 236                 chain = jumpstack[stackptr].chain;
 237                 rules = jumpstack[stackptr].rules;
 238                 goto next_rule;
 239         }
 240
 241         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 242
 243         if (static_branch_unlikely(&nft_counters_enabled))
 244                 nft_update_chain_stats(basechain, pkt);
 245
 246         return nft_base_chain(basechain)->policy;
 247 }
 248 EXPORT_SYMBOL_GPL(nft_do_chain);
 249
 250 static struct nft_expr_type *nft_basic_types[] = {
 251         &nft_imm_type,
 252         &nft_cmp_type,
 253         &nft_lookup_type,
 254         &nft_bitwise_type,
 255         &nft_byteorder_type,
 256         &nft_payload_type,
 257         &nft_dynset_type,
 258         &nft_range_type,
 259         &nft_meta_type,
 260         &nft_rt_type,
 261         &nft_exthdr_type,
 262 };
 263
 264 static struct nft_object_type *nft_basic_objects[] = {
 265 #ifdef CONFIG_NETWORK_SECMARK
 266         &nft_secmark_obj_type,
 267 #endif
 268 };
 269
 270 int __init nf_tables_core_module_init(void)
 271 {
 272         int err, i, j = 0;
 273
 274         for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
 275                 err = nft_register_obj(nft_basic_objects[i]);
 276                 if (err)
 277                         goto err;
 278         }
 279
 280         for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
 281                 err = nft_register_expr(nft_basic_types[j]);
 282                 if (err)
 283                         goto err;
 284         }
 285
 286         return 0;
 287
 288 err:
 289         while (j-- > 0)
 290                 nft_unregister_expr(nft_basic_types[j]);
 291
 292         while (i-- > 0)
 293                 nft_unregister_obj(nft_basic_objects[i]);
 294
 295         return err;
 296 }
 297
 298 void nf_tables_core_module_exit(void)
 299 {
 300         int i;
 301
 302         i = ARRAY_SIZE(nft_basic_types);
 303         while (i-- > 0)
 304                 nft_unregister_expr(nft_basic_types[i]);
 305
 306         i = ARRAY_SIZE(nft_basic_objects);
 307         while (i-- > 0)
 308                 nft_unregister_obj(nft_basic_objects[i]);
 309 }