1 /* 2 * Rusty Russell (C)2000 -- This code is GPL. 3 * Patrick McHardy (c) 2006-2012 4 */ 5 6 #include <linux/kernel.h> 7 #include <linux/slab.h> 8 #include <linux/init.h> 9 #include <linux/module.h> 10 #include <linux/proc_fs.h> 11 #include <linux/skbuff.h> 12 #include <linux/netfilter.h> 13 #include <linux/netfilter_ipv4.h> 14 #include <linux/netfilter_ipv6.h> 15 #include <linux/netfilter_bridge.h> 16 #include <linux/seq_file.h> 17 #include <linux/rcupdate.h> 18 #include <net/protocol.h> 19 #include <net/netfilter/nf_queue.h> 20 #include <net/dst.h> 21 22 #include "nf_internals.h" 23 24 static const struct nf_queue_handler __rcu *nf_queue_handler; 25 26 /* 27 * Hook for nfnetlink_queue to register its queue handler. 28 * We do this so that most of the NFQUEUE code can be modular. 29 * 30 * Once the queue is registered it must reinject all packets it 31 * receives, no matter what. 32 */ 33 34 void nf_register_queue_handler(const struct nf_queue_handler *qh) 35 { 36 /* should never happen, we only have one queueing backend in kernel */ 37 WARN_ON(rcu_access_pointer(nf_queue_handler)); 38 rcu_assign_pointer(nf_queue_handler, qh); 39 } 40 EXPORT_SYMBOL(nf_register_queue_handler); 41 42 /* The caller must flush their queue before this */ 43 void nf_unregister_queue_handler(void) 44 { 45 RCU_INIT_POINTER(nf_queue_handler, NULL); 46 } 47 EXPORT_SYMBOL(nf_unregister_queue_handler); 48 49 static void nf_queue_sock_put(struct sock *sk) 50 { 51 #ifdef CONFIG_INET 52 sock_gen_put(sk); 53 #else 54 sock_put(sk); 55 #endif 56 } 57 58 static void nf_queue_entry_release_refs(struct nf_queue_entry *entry) 59 { 60 struct nf_hook_state *state = &entry->state; 61 62 /* Release those devices we held, or Alexey will kill me. */ 63 dev_put(state->in); 64 dev_put(state->out); 65 if (state->sk) 66 nf_queue_sock_put(state->sk); 67 68 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 69 dev_put(entry->physin); 70 dev_put(entry->physout); 71 #endif 72 } 73 74 void nf_queue_entry_free(struct nf_queue_entry *entry) 75 { 76 nf_queue_entry_release_refs(entry); 77 kfree(entry); 78 } 79 EXPORT_SYMBOL_GPL(nf_queue_entry_free); 80 81 static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry) 82 { 83 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 84 const struct sk_buff *skb = entry->skb; 85 86 if (nf_bridge_info_exists(skb)) { 87 entry->physin = nf_bridge_get_physindev(skb, entry->state.net); 88 entry->physout = nf_bridge_get_physoutdev(skb); 89 } else { 90 entry->physin = NULL; 91 entry->physout = NULL; 92 } 93 #endif 94 } 95 96 /* Bump dev refs so they don't vanish while packet is out */ 97 bool nf_queue_entry_get_refs(struct nf_queue_entry *entry) 98 { 99 struct nf_hook_state *state = &entry->state; 100 101 if (state->sk && !refcount_inc_not_zero(&state->sk->sk_refcnt)) 102 return false; 103 104 dev_hold(state->in); 105 dev_hold(state->out); 106 107 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 108 dev_hold(entry->physin); 109 dev_hold(entry->physout); 110 #endif 111 return true; 112 } 113 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 114 115 void nf_queue_nf_hook_drop(struct net *net) 116 { 117 const struct nf_queue_handler *qh; 118 119 rcu_read_lock(); 120 qh = rcu_dereference(nf_queue_handler); 121 if (qh) 122 qh->nf_hook_drop(net); 123 rcu_read_unlock(); 124 } 125 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop); 126 127 static void nf_ip_saveroute(const struct sk_buff *skb, 128 struct nf_queue_entry *entry) 129 { 130 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); 131 132 if (entry->state.hook == NF_INET_LOCAL_OUT) { 133 const struct iphdr *iph = ip_hdr(skb); 134 135 rt_info->tos = iph->tos; 136 rt_info->daddr = iph->daddr; 137 rt_info->saddr = iph->saddr; 138 rt_info->mark = skb->mark; 139 } 140 } 141 142 static void nf_ip6_saveroute(const struct sk_buff *skb, 143 struct nf_queue_entry *entry) 144 { 145 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 146 147 if (entry->state.hook == NF_INET_LOCAL_OUT) { 148 const struct ipv6hdr *iph = ipv6_hdr(skb); 149 150 rt_info->daddr = iph->daddr; 151 rt_info->saddr = iph->saddr; 152 rt_info->mark = skb->mark; 153 } 154 } 155 156 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, 157 unsigned int index, unsigned int queuenum) 158 { 159 struct nf_queue_entry *entry = NULL; 160 const struct nf_queue_handler *qh; 161 unsigned int route_key_size; 162 int status; 163 164 /* QUEUE == DROP if no one is waiting, to be safe. */ 165 qh = rcu_dereference(nf_queue_handler); 166 if (!qh) 167 return -ESRCH; 168 169 switch (state->pf) { 170 case AF_INET: 171 route_key_size = sizeof(struct ip_rt_info); 172 break; 173 case AF_INET6: 174 route_key_size = sizeof(struct ip6_rt_info); 175 break; 176 default: 177 route_key_size = 0; 178 break; 179 } 180 181 if (skb_sk_is_prefetched(skb)) { 182 struct sock *sk = skb->sk; 183 184 if (!sk_is_refcounted(sk)) { 185 if (!refcount_inc_not_zero(&sk->sk_refcnt)) 186 return -ENOTCONN; 187 188 /* drop refcount on skb_orphan */ 189 skb->destructor = sock_edemux; 190 } 191 } 192 193 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC); 194 if (!entry) 195 return -ENOMEM; 196 197 if (skb_dst(skb) && !skb_dst_force(skb)) { 198 kfree(entry); 199 return -ENETDOWN; 200 } 201 202 *entry = (struct nf_queue_entry) { 203 .skb = skb, 204 .state = *state, 205 .hook_index = index, 206 .size = sizeof(*entry) + route_key_size, 207 }; 208 209 __nf_queue_entry_init_physdevs(entry); 210 211 if (!nf_queue_entry_get_refs(entry)) { 212 kfree(entry); 213 return -ENOTCONN; 214 } 215 216 switch (entry->state.pf) { 217 case AF_INET: 218 nf_ip_saveroute(skb, entry); 219 break; 220 case AF_INET6: 221 nf_ip6_saveroute(skb, entry); 222 break; 223 } 224 225 status = qh->outfn(entry, queuenum); 226 if (status < 0) { 227 nf_queue_entry_free(entry); 228 return status; 229 } 230 231 return 0; 232 } 233 234 /* Packets leaving via this function must come back through nf_reinject(). */ 235 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state, 236 unsigned int index, unsigned int verdict) 237 { 238 int ret; 239 240 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS); 241 if (ret < 0) { 242 if (ret == -ESRCH && 243 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 244 return 1; 245 kfree_skb(skb); 246 } 247 248 return 0; 249 } 250 EXPORT_SYMBOL_GPL(nf_queue); 251 252 static unsigned int nf_iterate(struct sk_buff *skb, 253 struct nf_hook_state *state, 254 const struct nf_hook_entries *hooks, 255 unsigned int *index) 256 { 257 const struct nf_hook_entry *hook; 258 unsigned int verdict, i = *index; 259 260 while (i < hooks->num_hook_entries) { 261 hook = &hooks->hooks[i]; 262 repeat: 263 verdict = nf_hook_entry_hookfn(hook, skb, state); 264 if (verdict != NF_ACCEPT) { 265 *index = i; 266 if (verdict != NF_REPEAT) 267 return verdict; 268 goto repeat; 269 } 270 i++; 271 } 272 273 *index = i; 274 return NF_ACCEPT; 275 } 276 277 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum) 278 { 279 switch (pf) { 280 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 281 case NFPROTO_BRIDGE: 282 return rcu_dereference(net->nf.hooks_bridge[hooknum]); 283 #endif 284 case NFPROTO_IPV4: 285 return rcu_dereference(net->nf.hooks_ipv4[hooknum]); 286 case NFPROTO_IPV6: 287 return rcu_dereference(net->nf.hooks_ipv6[hooknum]); 288 default: 289 WARN_ON_ONCE(1); 290 return NULL; 291 } 292 293 return NULL; 294 } 295 296 /* Caller must hold rcu read-side lock */ 297 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 298 { 299 const struct nf_hook_entry *hook_entry; 300 const struct nf_hook_entries *hooks; 301 struct sk_buff *skb = entry->skb; 302 const struct net *net; 303 unsigned int i; 304 int err; 305 u8 pf; 306 307 net = entry->state.net; 308 pf = entry->state.pf; 309 310 hooks = nf_hook_entries_head(net, pf, entry->state.hook); 311 312 i = entry->hook_index; 313 if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) { 314 kfree_skb(skb); 315 nf_queue_entry_free(entry); 316 return; 317 } 318 319 hook_entry = &hooks->hooks[i]; 320 321 /* Continue traversal iff userspace said ok... */ 322 if (verdict == NF_REPEAT) 323 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state); 324 325 if (verdict == NF_ACCEPT) { 326 if (nf_reroute(skb, entry) < 0) 327 verdict = NF_DROP; 328 } 329 330 if (verdict == NF_ACCEPT) { 331 next_hook: 332 ++i; 333 verdict = nf_iterate(skb, &entry->state, hooks, &i); 334 } 335 336 switch (verdict & NF_VERDICT_MASK) { 337 case NF_ACCEPT: 338 case NF_STOP: 339 local_bh_disable(); 340 entry->state.okfn(entry->state.net, entry->state.sk, skb); 341 local_bh_enable(); 342 break; 343 case NF_QUEUE: 344 err = nf_queue(skb, &entry->state, i, verdict); 345 if (err == 1) 346 goto next_hook; 347 break; 348 case NF_STOLEN: 349 break; 350 default: 351 kfree_skb(skb); 352 } 353 354 nf_queue_entry_free(entry); 355 } 356 EXPORT_SYMBOL(nf_reinject); 357