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Linux/net/netfilter/nf_tables_core.c

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  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_trace(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_regs *regs)
 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 ((regs->data[priv->sreg] & mask) == priv->data)
 74                 return;
 75         regs->verdict.code = NFT_BREAK;
 76 }
 77 
 78 static bool nft_payload_fast_eval(const struct nft_expr *expr,
 79                                   struct nft_regs *regs,
 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         u32 *dest = &regs->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         *dest = 0;
 98         if (priv->len == 2)
 99                 *(u16 *)dest = *(u16 *)ptr;
100         else if (priv->len == 4)
101                 *(u32 *)dest = *(u32 *)ptr;
102         else
103                 *(u8 *)dest = *(u8 *)ptr;
104         return true;
105 }
106 
107 struct nft_jumpstack {
108         const struct nft_chain  *chain;
109         const struct nft_rule   *rule;
110         int                     rulenum;
111 };
112 
113 unsigned int
114 nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
115 {
116         const struct nft_chain *chain = ops->priv, *basechain = chain;
117         const struct net *chain_net = read_pnet(&nft_base_chain(basechain)->pnet);
118         const struct net *net = dev_net(pkt->in ? pkt->in : pkt->out);
119         const struct nft_rule *rule;
120         const struct nft_expr *expr, *last;
121         struct nft_regs regs;
122         unsigned int stackptr = 0;
123         struct nft_jumpstack jumpstack[NFT_JUMP_STACK_SIZE];
124         struct nft_stats *stats;
125         int rulenum;
126         unsigned int gencursor = nft_genmask_cur(net);
127 
128         /* Ignore chains that are not for the current network namespace */
129         if (!net_eq(net, chain_net))
130                 return NF_ACCEPT;
131 
132 do_chain:
133         rulenum = 0;
134         rule = list_entry(&chain->rules, struct nft_rule, list);
135 next_rule:
136         regs.verdict.code = NFT_CONTINUE;
137         list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
138 
139                 /* This rule is not active, skip. */
140                 if (unlikely(rule->genmask & (1 << gencursor)))
141                         continue;
142 
143                 rulenum++;
144 
145                 nft_rule_for_each_expr(expr, last, rule) {
146                         if (expr->ops == &nft_cmp_fast_ops)
147                                 nft_cmp_fast_eval(expr, &regs);
148                         else if (expr->ops != &nft_payload_fast_ops ||
149                                  !nft_payload_fast_eval(expr, &regs, pkt))
150                                 expr->ops->eval(expr, &regs, pkt);
151 
152                         if (regs.verdict.code != NFT_CONTINUE)
153                                 break;
154                 }
155 
156                 switch (regs.verdict.code) {
157                 case NFT_BREAK:
158                         regs.verdict.code = NFT_CONTINUE;
159                         continue;
160                 case NFT_CONTINUE:
161                         nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
162                         continue;
163                 }
164                 break;
165         }
166 
167         switch (regs.verdict.code & NF_VERDICT_MASK) {
168         case NF_ACCEPT:
169         case NF_DROP:
170         case NF_QUEUE:
171                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
172                 return regs.verdict.code;
173         }
174 
175         switch (regs.verdict.code) {
176         case NFT_JUMP:
177                 BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
178                 jumpstack[stackptr].chain = chain;
179                 jumpstack[stackptr].rule  = rule;
180                 jumpstack[stackptr].rulenum = rulenum;
181                 stackptr++;
182                 /* fall through */
183         case NFT_GOTO:
184                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
185 
186                 chain = regs.verdict.chain;
187                 goto do_chain;
188         case NFT_CONTINUE:
189                 rulenum++;
190                 /* fall through */
191         case NFT_RETURN:
192                 nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RETURN);
193                 break;
194         default:
195                 WARN_ON(1);
196         }
197 
198         if (stackptr > 0) {
199                 stackptr--;
200                 chain = jumpstack[stackptr].chain;
201                 rule  = jumpstack[stackptr].rule;
202                 rulenum = jumpstack[stackptr].rulenum;
203                 goto next_rule;
204         }
205 
206         nft_trace_packet(pkt, basechain, -1, NFT_TRACE_POLICY);
207 
208         rcu_read_lock_bh();
209         stats = this_cpu_ptr(rcu_dereference(nft_base_chain(basechain)->stats));
210         u64_stats_update_begin(&stats->syncp);
211         stats->pkts++;
212         stats->bytes += pkt->skb->len;
213         u64_stats_update_end(&stats->syncp);
214         rcu_read_unlock_bh();
215 
216         return nft_base_chain(basechain)->policy;
217 }
218 EXPORT_SYMBOL_GPL(nft_do_chain);
219 
220 int __init nf_tables_core_module_init(void)
221 {
222         int err;
223 
224         err = nft_immediate_module_init();
225         if (err < 0)
226                 goto err1;
227 
228         err = nft_cmp_module_init();
229         if (err < 0)
230                 goto err2;
231 
232         err = nft_lookup_module_init();
233         if (err < 0)
234                 goto err3;
235 
236         err = nft_bitwise_module_init();
237         if (err < 0)
238                 goto err4;
239 
240         err = nft_byteorder_module_init();
241         if (err < 0)
242                 goto err5;
243 
244         err = nft_payload_module_init();
245         if (err < 0)
246                 goto err6;
247 
248         err = nft_dynset_module_init();
249         if (err < 0)
250                 goto err7;
251 
252         return 0;
253 
254 err7:
255         nft_payload_module_exit();
256 err6:
257         nft_byteorder_module_exit();
258 err5:
259         nft_bitwise_module_exit();
260 err4:
261         nft_lookup_module_exit();
262 err3:
263         nft_cmp_module_exit();
264 err2:
265         nft_immediate_module_exit();
266 err1:
267         return err;
268 }
269 
270 void nf_tables_core_module_exit(void)
271 {
272         nft_dynset_module_exit();
273         nft_payload_module_exit();
274         nft_byteorder_module_exit();
275         nft_bitwise_module_exit();
276         nft_lookup_module_exit();
277         nft_cmp_module_exit();
278         nft_immediate_module_exit();
279 }
280 

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