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_refs(struct nf_queue_entry *entry) 50 { 51 struct nf_hook_state *state = &entry->state; 52 53 /* Release those devices we held, or Alexey will kill me. */ 54 if (state->in) 55 dev_put(state->in); 56 if (state->out) 57 dev_put(state->out); 58 if (state->sk) 59 sock_put(state->sk); 60 61 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 62 if (entry->physin) 63 dev_put(entry->physin); 64 if (entry->physout) 65 dev_put(entry->physout); 66 #endif 67 } 68 69 void nf_queue_entry_free(struct nf_queue_entry *entry) 70 { 71 nf_queue_entry_release_refs(entry); 72 kfree(entry); 73 } 74 EXPORT_SYMBOL_GPL(nf_queue_entry_free); 75 76 static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry) 77 { 78 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 79 const struct sk_buff *skb = entry->skb; 80 struct nf_bridge_info *nf_bridge; 81 82 nf_bridge = nf_bridge_info_get(skb); 83 if (nf_bridge) { 84 entry->physin = nf_bridge_get_physindev(skb); 85 entry->physout = nf_bridge_get_physoutdev(skb); 86 } else { 87 entry->physin = NULL; 88 entry->physout = NULL; 89 } 90 #endif 91 } 92 93 /* Bump dev refs so they don't vanish while packet is out */ 94 void nf_queue_entry_get_refs(struct nf_queue_entry *entry) 95 { 96 struct nf_hook_state *state = &entry->state; 97 98 if (state->in) 99 dev_hold(state->in); 100 if (state->out) 101 dev_hold(state->out); 102 if (state->sk) 103 sock_hold(state->sk); 104 105 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 106 if (entry->physin) 107 dev_hold(entry->physin); 108 if (entry->physout) 109 dev_hold(entry->physout); 110 #endif 111 } 112 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 113 114 void nf_queue_nf_hook_drop(struct net *net) 115 { 116 const struct nf_queue_handler *qh; 117 118 rcu_read_lock(); 119 qh = rcu_dereference(net->nf.queue_handler); 120 if (qh) 121 qh->nf_hook_drop(net); 122 rcu_read_unlock(); 123 } 124 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop); 125 126 static void nf_ip_saveroute(const struct sk_buff *skb, 127 struct nf_queue_entry *entry) 128 { 129 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry); 130 131 if (entry->state.hook == NF_INET_LOCAL_OUT) { 132 const struct iphdr *iph = ip_hdr(skb); 133 134 rt_info->tos = iph->tos; 135 rt_info->daddr = iph->daddr; 136 rt_info->saddr = iph->saddr; 137 rt_info->mark = skb->mark; 138 } 139 } 140 141 static void nf_ip6_saveroute(const struct sk_buff *skb, 142 struct nf_queue_entry *entry) 143 { 144 struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry); 145 146 if (entry->state.hook == NF_INET_LOCAL_OUT) { 147 const struct ipv6hdr *iph = ipv6_hdr(skb); 148 149 rt_info->daddr = iph->daddr; 150 rt_info->saddr = iph->saddr; 151 rt_info->mark = skb->mark; 152 } 153 } 154 155 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, 156 unsigned int index, unsigned int queuenum) 157 { 158 struct nf_queue_entry *entry = NULL; 159 const struct nf_queue_handler *qh; 160 struct net *net = state->net; 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(net->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 entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC); 182 if (!entry) 183 return -ENOMEM; 184 185 if (skb_dst(skb) && !skb_dst_force(skb)) { 186 kfree(entry); 187 return -ENETDOWN; 188 } 189 190 *entry = (struct nf_queue_entry) { 191 .skb = skb, 192 .state = *state, 193 .hook_index = index, 194 .size = sizeof(*entry) + route_key_size, 195 }; 196 197 __nf_queue_entry_init_physdevs(entry); 198 199 nf_queue_entry_get_refs(entry); 200 201 switch (entry->state.pf) { 202 case AF_INET: 203 nf_ip_saveroute(skb, entry); 204 break; 205 case AF_INET6: 206 nf_ip6_saveroute(skb, entry); 207 break; 208 } 209 210 status = qh->outfn(entry, queuenum); 211 if (status < 0) { 212 nf_queue_entry_free(entry); 213 return status; 214 } 215 216 return 0; 217 } 218 219 /* Packets leaving via this function must come back through nf_reinject(). */ 220 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state, 221 unsigned int index, unsigned int verdict) 222 { 223 int ret; 224 225 ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS); 226 if (ret < 0) { 227 if (ret == -ESRCH && 228 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 229 return 1; 230 kfree_skb(skb); 231 } 232 233 return 0; 234 } 235 EXPORT_SYMBOL_GPL(nf_queue); 236 237 static unsigned int nf_iterate(struct sk_buff *skb, 238 struct nf_hook_state *state, 239 const struct nf_hook_entries *hooks, 240 unsigned int *index) 241 { 242 const struct nf_hook_entry *hook; 243 unsigned int verdict, i = *index; 244 245 while (i < hooks->num_hook_entries) { 246 hook = &hooks->hooks[i]; 247 repeat: 248 verdict = nf_hook_entry_hookfn(hook, skb, state); 249 if (verdict != NF_ACCEPT) { 250 *index = i; 251 if (verdict != NF_REPEAT) 252 return verdict; 253 goto repeat; 254 } 255 i++; 256 } 257 258 *index = i; 259 return NF_ACCEPT; 260 } 261 262 static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum) 263 { 264 switch (pf) { 265 #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE 266 case NFPROTO_BRIDGE: 267 return rcu_dereference(net->nf.hooks_bridge[hooknum]); 268 #endif 269 case NFPROTO_IPV4: 270 return rcu_dereference(net->nf.hooks_ipv4[hooknum]); 271 case NFPROTO_IPV6: 272 return rcu_dereference(net->nf.hooks_ipv6[hooknum]); 273 default: 274 WARN_ON_ONCE(1); 275 return NULL; 276 } 277 278 return NULL; 279 } 280 281 /* Caller must hold rcu read-side lock */ 282 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 283 { 284 const struct nf_hook_entry *hook_entry; 285 const struct nf_hook_entries *hooks; 286 struct sk_buff *skb = entry->skb; 287 const struct net *net; 288 unsigned int i; 289 int err; 290 u8 pf; 291 292 net = entry->state.net; 293 pf = entry->state.pf; 294 295 hooks = nf_hook_entries_head(net, pf, entry->state.hook); 296 297 i = entry->hook_index; 298 if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) { 299 kfree_skb(skb); 300 nf_queue_entry_free(entry); 301 return; 302 } 303 304 hook_entry = &hooks->hooks[i]; 305 306 /* Continue traversal iff userspace said ok... */ 307 if (verdict == NF_REPEAT) 308 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state); 309 310 if (verdict == NF_ACCEPT) { 311 if (nf_reroute(skb, entry) < 0) 312 verdict = NF_DROP; 313 } 314 315 if (verdict == NF_ACCEPT) { 316 next_hook: 317 ++i; 318 verdict = nf_iterate(skb, &entry->state, hooks, &i); 319 } 320 321 switch (verdict & NF_VERDICT_MASK) { 322 case NF_ACCEPT: 323 case NF_STOP: 324 local_bh_disable(); 325 entry->state.okfn(entry->state.net, entry->state.sk, skb); 326 local_bh_enable(); 327 break; 328 case NF_QUEUE: 329 err = nf_queue(skb, &entry->state, i, verdict); 330 if (err == 1) 331 goto next_hook; 332 break; 333 case NF_STOLEN: 334 break; 335 default: 336 kfree_skb(skb); 337 } 338 339 nf_queue_entry_free(entry); 340 } 341 EXPORT_SYMBOL(nf_reinject); 342