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