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 /* 25 * Hook for nfnetlink_queue to register its queue handler. 26 * We do this so that most of the NFQUEUE code can be modular. 27 * 28 * Once the queue is registered it must reinject all packets it 29 * receives, no matter what. 30 */ 31 32 /* return EBUSY when somebody else is registered, return EEXIST if the 33 * same handler is registered, return 0 in case of success. */ 34 void nf_register_queue_handler(struct net *net, 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(net->nf.queue_handler)); 38 rcu_assign_pointer(net->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(struct net *net) 44 { 45 RCU_INIT_POINTER(net->nf.queue_handler, NULL); 46 } 47 EXPORT_SYMBOL(nf_unregister_queue_handler); 48 49 static void nf_queue_entry_release_br_nf_refs(struct sk_buff *skb) 50 { 51 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 52 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 53 54 if (nf_bridge) { 55 struct net_device *physdev; 56 57 physdev = nf_bridge_get_physindev(skb); 58 if (physdev) 59 dev_put(physdev); 60 physdev = nf_bridge_get_physoutdev(skb); 61 if (physdev) 62 dev_put(physdev); 63 } 64 #endif 65 } 66 67 void nf_queue_entry_release_refs(struct nf_queue_entry *entry) 68 { 69 struct nf_hook_state *state = &entry->state; 70 71 /* Release those devices we held, or Alexey will kill me. */ 72 if (state->in) 73 dev_put(state->in); 74 if (state->out) 75 dev_put(state->out); 76 if (state->sk) 77 sock_put(state->sk); 78 79 nf_queue_entry_release_br_nf_refs(entry->skb); 80 } 81 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); 82 83 static void nf_queue_entry_get_br_nf_refs(struct sk_buff *skb) 84 { 85 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 86 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 87 88 if (nf_bridge) { 89 struct net_device *physdev; 90 91 physdev = nf_bridge_get_physindev(skb); 92 if (physdev) 93 dev_hold(physdev); 94 physdev = nf_bridge_get_physoutdev(skb); 95 if (physdev) 96 dev_hold(physdev); 97 } 98 #endif 99 } 100 101 /* Bump dev refs so they don't vanish while packet is out */ 102 void nf_queue_entry_get_refs(struct nf_queue_entry *entry) 103 { 104 struct nf_hook_state *state = &entry->state; 105 106 if (state->in) 107 dev_hold(state->in); 108 if (state->out) 109 dev_hold(state->out); 110 if (state->sk) 111 sock_hold(state->sk); 112 113 nf_queue_entry_get_br_nf_refs(entry->skb); 114 } 115 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 116 117 void nf_queue_nf_hook_drop(struct net *net) 118 { 119 const struct nf_queue_handler *qh; 120 121 rcu_read_lock(); 122 qh = rcu_dereference(net->nf.queue_handler); 123 if (qh) 124 qh->nf_hook_drop(net); 125 rcu_read_unlock(); 126 } 127 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop); 128 129 static void nf_ip_saveroute(const struct sk_buff *skb, 130 struct nf_queue_entry *entry) 131 { 132 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); 133 134 if (entry->state.hook == NF_INET_LOCAL_OUT) { 135 const struct iphdr *iph = ip_hdr(skb); 136 137 rt_info->tos = iph->tos; 138 rt_info->daddr = iph->daddr; 139 rt_info->saddr = iph->saddr; 140 rt_info->mark = skb->mark; 141 } 142 } 143 144 static void nf_ip6_saveroute(const struct sk_buff *skb, 145 struct nf_queue_entry *entry) 146 { 147 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 148 149 if (entry->state.hook == NF_INET_LOCAL_OUT) { 150 const struct ipv6hdr *iph = ipv6_hdr(skb); 151 152 rt_info->daddr = iph->daddr; 153 rt_info->saddr = iph->saddr; 154 rt_info->mark = skb->mark; 155 } 156 } 157 158 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, 159 unsigned int index, unsigned int queuenum) 160 { 161 int status = -ENOENT; 162 struct nf_queue_entry *entry = NULL; 163 const struct nf_queue_handler *qh; 164 struct net *net = state->net; 165 unsigned int route_key_size; 166 167 /* QUEUE == DROP if no one is waiting, to be safe. */ 168 qh = rcu_dereference(net->nf.queue_handler); 169 if (!qh) { 170 status = -ESRCH; 171 goto err; 172 } 173 174 switch (state->pf) { 175 case AF_INET: 176 route_key_size = sizeof(struct ip_rt_info); 177 break; 178 case AF_INET6: 179 route_key_size = sizeof(struct ip6_rt_info); 180 break; 181 default: 182 route_key_size = 0; 183 break; 184 } 185 186 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC); 187 if (!entry) { 188 status = -ENOMEM; 189 goto err; 190 } 191 192 if (skb_dst(skb) && !skb_dst_force(skb)) { 193 status = -ENETDOWN; 194 goto err; 195 } 196 197 *entry = (struct nf_queue_entry) { 198 .skb = skb, 199 .state = *state, 200 .hook_index = index, 201 .size = sizeof(*entry) + route_key_size, 202 }; 203 204 nf_queue_entry_get_refs(entry); 205 206 switch (entry->state.pf) { 207 case AF_INET: 208 nf_ip_saveroute(skb, entry); 209 break; 210 case AF_INET6: 211 nf_ip6_saveroute(skb, entry); 212 break; 213 } 214 215 status = qh->outfn(entry, queuenum); 216 217 if (status < 0) { 218 nf_queue_entry_release_refs(entry); 219 goto err; 220 } 221 222 return 0; 223 224 err: 225 kfree(entry); 226 return status; 227 } 228 229 /* Packets leaving via this function must come back through nf_reinject(). */ 230 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state, 231 unsigned int index, unsigned int verdict) 232 { 233 int ret; 234 235 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS); 236 if (ret < 0) { 237 if (ret == -ESRCH && 238 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 239 return 1; 240 kfree_skb(skb); 241 } 242 243 return 0; 244 } 245 EXPORT_SYMBOL_GPL(nf_queue); 246 247 static unsigned int nf_iterate(struct sk_buff *skb, 248 struct nf_hook_state *state, 249 const struct nf_hook_entries *hooks, 250 unsigned int *index) 251 { 252 const struct nf_hook_entry *hook; 253 unsigned int verdict, i = *index; 254 255 while (i < hooks->num_hook_entries) { 256 hook = &hooks->hooks[i]; 257 repeat: 258 verdict = nf_hook_entry_hookfn(hook, skb, state); 259 if (verdict != NF_ACCEPT) { 260 *index = i; 261 if (verdict != NF_REPEAT) 262 return verdict; 263 goto repeat; 264 } 265 i++; 266 } 267 268 *index = i; 269 return NF_ACCEPT; 270 } 271 272 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum) 273 { 274 switch (pf) { 275 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 276 case NFPROTO_BRIDGE: 277 return rcu_dereference(net->nf.hooks_bridge[hooknum]); 278 #endif 279 case NFPROTO_IPV4: 280 return rcu_dereference(net->nf.hooks_ipv4[hooknum]); 281 case NFPROTO_IPV6: 282 return rcu_dereference(net->nf.hooks_ipv6[hooknum]); 283 default: 284 WARN_ON_ONCE(1); 285 return NULL; 286 } 287 288 return NULL; 289 } 290 291 /* Caller must hold rcu read-side lock */ 292 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 293 { 294 const struct nf_hook_entry *hook_entry; 295 const struct nf_hook_entries *hooks; 296 struct sk_buff *skb = entry->skb; 297 const struct net *net; 298 unsigned int i; 299 int err; 300 u8 pf; 301 302 net = entry->state.net; 303 pf = entry->state.pf; 304 305 hooks = nf_hook_entries_head(net, pf, entry->state.hook); 306 307 nf_queue_entry_release_refs(entry); 308 309 i = entry->hook_index; 310 if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) { 311 kfree_skb(skb); 312 kfree(entry); 313 return; 314 } 315 316 hook_entry = &hooks->hooks[i]; 317 318 /* Continue traversal iff userspace said ok... */ 319 if (verdict == NF_REPEAT) 320 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state); 321 322 if (verdict == NF_ACCEPT) { 323 if (nf_reroute(skb, entry) < 0) 324 verdict = NF_DROP; 325 } 326 327 if (verdict == NF_ACCEPT) { 328 next_hook: 329 ++i; 330 verdict = nf_iterate(skb, &entry->state, hooks, &i); 331 } 332 333 switch (verdict & NF_VERDICT_MASK) { 334 case NF_ACCEPT: 335 case NF_STOP: 336 local_bh_disable(); 337 entry->state.okfn(entry->state.net, entry->state.sk, skb); 338 local_bh_enable(); 339 break; 340 case NF_QUEUE: 341 err = nf_queue(skb, &entry->state, i, verdict); 342 if (err == 1) 343 goto next_hook; 344 break; 345 case NF_STOLEN: 346 break; 347 default: 348 kfree_skb(skb); 349 } 350 351 kfree(entry); 352 } 353 EXPORT_SYMBOL(nf_reinject); 354