net/netfilter/nf_tables_core.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
   4  *
   5  * Development of this code funded by Astaro AG (http://www.astaro.com/)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/rculist.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/netlink.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/static_key.h>
  17 #include <linux/netfilter/nfnetlink.h>
  18 #include <linux/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_tables_core.h>
  20 #include <net/netfilter/nf_tables.h>
  21 #include <net/netfilter/nf_log.h>
  22 #include <net/netfilter/nft_meta.h>
  23
  24 static noinline void __nft_trace_packet(struct nft_traceinfo *info,
  25                                         const struct nft_chain *chain,
  26                                         enum nft_trace_types type)
  27 {
  28         const struct nft_pktinfo *pkt = info->pkt;
  29
  30         if (!info->trace || !pkt->skb->nf_trace)
  31                 return;
  32
  33         info->chain = chain;
  34         info->type = type;
  35
  36         nft_trace_notify(info);
  37 }
  38
  39 static inline void nft_trace_packet(struct nft_traceinfo *info,
  40                                     const struct nft_chain *chain,
  41                                     const struct nft_rule *rule,
  42                                     enum nft_trace_types type)
  43 {
  44         if (static_branch_unlikely(&nft_trace_enabled)) {
  45                 info->rule = rule;
  46                 __nft_trace_packet(info, chain, type);
  47         }
  48 }
  49
  50 static void nft_bitwise_fast_eval(const struct nft_expr *expr,
  51                                   struct nft_regs *regs)
  52 {
  53         const struct nft_bitwise_fast_expr *priv = nft_expr_priv(expr);
  54         u32 *src = &regs->data[priv->sreg];
  55         u32 *dst = &regs->data[priv->dreg];
  56
  57         *dst = (*src & priv->mask) ^ priv->xor;
  58 }
  59
  60 static void nft_cmp_fast_eval(const struct nft_expr *expr,
  61                               struct nft_regs *regs)
  62 {
  63         const struct nft_cmp_fast_expr *priv = nft_expr_priv(expr);
  64
  65         if (((regs->data[priv->sreg] & priv->mask) == priv->data) ^ priv->inv)
  66                 return;
  67         regs->verdict.code = NFT_BREAK;
  68 }
  69
  70 static bool nft_payload_fast_eval(const struct nft_expr *expr,
  71                                   struct nft_regs *regs,
  72                                   const struct nft_pktinfo *pkt)
  73 {
  74         const struct nft_payload *priv = nft_expr_priv(expr);
  75         const struct sk_buff *skb = pkt->skb;
  76         u32 *dest = &regs->data[priv->dreg];
  77         unsigned char *ptr;
  78
  79         if (priv->base == NFT_PAYLOAD_NETWORK_HEADER)
  80                 ptr = skb_network_header(skb);
  81         else {
  82                 if (!pkt->tprot_set)
  83                         return false;
  84                 ptr = skb_network_header(skb) + pkt->xt.thoff;
  85         }
  86
  87         ptr += priv->offset;
  88
  89         if (unlikely(ptr + priv->len > skb_tail_pointer(skb)))
  90                 return false;
  91
  92         *dest = 0;
  93         if (priv->len == 2)
  94                 *(u16 *)dest = *(u16 *)ptr;
  95         else if (priv->len == 4)
  96                 *(u32 *)dest = *(u32 *)ptr;
  97         else
  98                 *(u8 *)dest = *(u8 *)ptr;
  99         return true;
 100 }
 101
 102 DEFINE_STATIC_KEY_FALSE(nft_counters_enabled);
 103
 104 static noinline void nft_update_chain_stats(const struct nft_chain *chain,
 105                                             const struct nft_pktinfo *pkt)
 106 {
 107         struct nft_base_chain *base_chain;
 108         struct nft_stats __percpu *pstats;
 109         struct nft_stats *stats;
 110
 111         base_chain = nft_base_chain(chain);
 112
 113         rcu_read_lock();
 114         pstats = READ_ONCE(base_chain->stats);
 115         if (pstats) {
 116                 local_bh_disable();
 117                 stats = this_cpu_ptr(pstats);
 118                 u64_stats_update_begin(&stats->syncp);
 119                 stats->pkts++;
 120                 stats->bytes += pkt->skb->len;
 121                 u64_stats_update_end(&stats->syncp);
 122                 local_bh_enable();
 123         }
 124         rcu_read_unlock();
 125 }
 126
 127 struct nft_jumpstack {
 128         const struct nft_chain  *chain;
 129         struct nft_rule *const *rules;
 130 };
 131
 132 static void expr_call_ops_eval(const struct nft_expr *expr,
 133                                struct nft_regs *regs,
 134                                struct nft_pktinfo *pkt)
 135 {
 136 #ifdef CONFIG_RETPOLINE
 137         unsigned long e = (unsigned long)expr->ops->eval;
 138 #define X(e, fun) \
 139         do { if ((e) == (unsigned long)(fun)) \
 140                 return fun(expr, regs, pkt); } while (0)
 141
 142         X(e, nft_payload_eval);
 143         X(e, nft_cmp_eval);
 144         X(e, nft_meta_get_eval);
 145         X(e, nft_lookup_eval);
 146         X(e, nft_range_eval);
 147         X(e, nft_immediate_eval);
 148         X(e, nft_byteorder_eval);
 149         X(e, nft_dynset_eval);
 150         X(e, nft_rt_get_eval);
 151         X(e, nft_bitwise_eval);
 152 #undef  X
 153 #endif /* CONFIG_RETPOLINE */
 154         expr->ops->eval(expr, regs, pkt);
 155 }
 156
 157 unsigned int
 158 nft_do_chain(struct nft_pktinfo *pkt, void *priv)
 159 {
 160         const struct nft_chain *chain = priv, *basechain = chain;
 161         const struct net *net = nft_net(pkt);
 162         struct nft_rule *const *rules;
 163         const struct nft_rule *rule;
 164         const struct nft_expr *expr, *last;
 165         struct nft_regs regs;
 166         unsigned int stackptr = 0;
 167         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
 168         bool genbit = READ_ONCE(net->nft.gencursor);
 169         struct nft_traceinfo info;
 170
 171         info.trace = false;
 172         if (static_branch_unlikely(&nft_trace_enabled))
 173                 nft_trace_init(&info, pkt, &regs.verdict, basechain);
 174 do_chain:
 175         if (genbit)
 176                 rules = rcu_dereference(chain->rules_gen_1);
 177         else
 178                 rules = rcu_dereference(chain->rules_gen_0);
 179
 180 next_rule:
 181         rule = *rules;
 182         regs.verdict.code = NFT_CONTINUE;
 183         for (; *rules ; rules++) {
 184                 rule = *rules;
 185                 nft_rule_for_each_expr(expr, last, rule) {
 186                         if (expr->ops == &nft_cmp_fast_ops)
 187                                 nft_cmp_fast_eval(expr, &regs);
 188                         else if (expr->ops == &nft_bitwise_fast_ops)
 189                                 nft_bitwise_fast_eval(expr, &regs);
 190                         else if (expr->ops != &nft_payload_fast_ops ||
 191                                  !nft_payload_fast_eval(expr, &regs, pkt))
 192                                 expr_call_ops_eval(expr, &regs, pkt);
 193
 194                         if (regs.verdict.code != NFT_CONTINUE)
 195                                 break;
 196                 }
 197
 198                 switch (regs.verdict.code) {
 199                 case NFT_BREAK:
 200                         regs.verdict.code = NFT_CONTINUE;
 201                         continue;
 202                 case NFT_CONTINUE:
 203                         nft_trace_packet(&info, chain, rule,
 204                                          NFT_TRACETYPE_RULE);
 205                         continue;
 206                 }
 207                 break;
 208         }
 209
 210         switch (regs.verdict.code & NF_VERDICT_MASK) {
 211         case NF_ACCEPT:
 212         case NF_DROP:
 213         case NF_QUEUE:
 214         case NF_STOLEN:
 215                 nft_trace_packet(&info, chain, rule,
 216                                  NFT_TRACETYPE_RULE);
 217                 return regs.verdict.code;
 218         }
 219
 220         switch (regs.verdict.code) {
 221         case NFT_JUMP:
 222                 if (WARN_ON_ONCE(stackptr >= NFT_JUMP_STACK_SIZE))
 223                         return NF_DROP;
 224                 jumpstack[stackptr].chain = chain;
 225                 jumpstack[stackptr].rules = rules + 1;
 226                 stackptr++;
 227                 fallthrough;
 228         case NFT_GOTO:
 229                 nft_trace_packet(&info, chain, rule,
 230                                  NFT_TRACETYPE_RULE);
 231
 232                 chain = regs.verdict.chain;
 233                 goto do_chain;
 234         case NFT_CONTINUE:
 235         case NFT_RETURN:
 236                 nft_trace_packet(&info, chain, rule,
 237                                  NFT_TRACETYPE_RETURN);
 238                 break;
 239         default:
 240                 WARN_ON(1);
 241         }
 242
 243         if (stackptr > 0) {
 244                 stackptr--;
 245                 chain = jumpstack[stackptr].chain;
 246                 rules = jumpstack[stackptr].rules;
 247                 goto next_rule;
 248         }
 249
 250         nft_trace_packet(&info, basechain, NULL, NFT_TRACETYPE_POLICY);
 251
 252         if (static_branch_unlikely(&nft_counters_enabled))
 253                 nft_update_chain_stats(basechain, pkt);
 254
 255         return nft_base_chain(basechain)->policy;
 256 }
 257 EXPORT_SYMBOL_GPL(nft_do_chain);
 258
 259 static struct nft_expr_type *nft_basic_types[] = {
 260         &nft_imm_type,
 261         &nft_cmp_type,
 262         &nft_lookup_type,
 263         &nft_bitwise_type,
 264         &nft_byteorder_type,
 265         &nft_payload_type,
 266         &nft_dynset_type,
 267         &nft_range_type,
 268         &nft_meta_type,
 269         &nft_rt_type,
 270         &nft_exthdr_type,
 271 };
 272
 273 static struct nft_object_type *nft_basic_objects[] = {
 274 #ifdef CONFIG_NETWORK_SECMARK
 275         &nft_secmark_obj_type,
 276 #endif
 277 };
 278
 279 int __init nf_tables_core_module_init(void)
 280 {
 281         int err, i, j = 0;
 282
 283         for (i = 0; i < ARRAY_SIZE(nft_basic_objects); i++) {
 284                 err = nft_register_obj(nft_basic_objects[i]);
 285                 if (err)
 286                         goto err;
 287         }
 288
 289         for (j = 0; j < ARRAY_SIZE(nft_basic_types); j++) {
 290                 err = nft_register_expr(nft_basic_types[j]);
 291                 if (err)
 292                         goto err;
 293         }
 294
 295         return 0;
 296
 297 err:
 298         while (j-- > 0)
 299                 nft_unregister_expr(nft_basic_types[j]);
 300
 301         while (i-- > 0)
 302                 nft_unregister_obj(nft_basic_objects[i]);
 303
 304         return err;
 305 }
 306
 307 void nf_tables_core_module_exit(void)
 308 {
 309         int i;
 310
 311         i = ARRAY_SIZE(nft_basic_types);
 312         while (i-- > 0)
 313                 nft_unregister_expr(nft_basic_types[i]);
 314
 315         i = ARRAY_SIZE(nft_basic_objects);
 316         while (i-- > 0)
 317                 nft_unregister_obj(nft_basic_objects[i]);
 318 }