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_bridge.h> 14 #include <linux/seq_file.h> 15 #include <linux/rcupdate.h> 16 #include <net/protocol.h> 17 #include <net/netfilter/nf_queue.h> 18 #include <net/dst.h> 19 20 #include "nf_internals.h" 21 22 /* 23 * Hook for nfnetlink_queue to register its queue handler. 24 * We do this so that most of the NFQUEUE code can be modular. 25 * 26 * Once the queue is registered it must reinject all packets it 27 * receives, no matter what. 28 */ 29 30 /* return EBUSY when somebody else is registered, return EEXIST if the 31 * same handler is registered, return 0 in case of success. */ 32 void nf_register_queue_handler(struct net *net, const struct nf_queue_handler *qh) 33 { 34 /* should never happen, we only have one queueing backend in kernel */ 35 WARN_ON(rcu_access_pointer(net->nf.queue_handler)); 36 rcu_assign_pointer(net->nf.queue_handler, qh); 37 } 38 EXPORT_SYMBOL(nf_register_queue_handler); 39 40 /* The caller must flush their queue before this */ 41 void nf_unregister_queue_handler(struct net *net) 42 { 43 RCU_INIT_POINTER(net->nf.queue_handler, NULL); 44 } 45 EXPORT_SYMBOL(nf_unregister_queue_handler); 46 47 void nf_queue_entry_release_refs(struct nf_queue_entry *entry) 48 { 49 struct nf_hook_state *state = &entry->state; 50 51 /* Release those devices we held, or Alexey will kill me. */ 52 if (state->in) 53 dev_put(state->in); 54 if (state->out) 55 dev_put(state->out); 56 if (state->sk) 57 sock_put(state->sk); 58 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 59 if (entry->skb->nf_bridge) { 60 struct net_device *physdev; 61 62 physdev = nf_bridge_get_physindev(entry->skb); 63 if (physdev) 64 dev_put(physdev); 65 physdev = nf_bridge_get_physoutdev(entry->skb); 66 if (physdev) 67 dev_put(physdev); 68 } 69 #endif 70 } 71 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); 72 73 /* Bump dev refs so they don't vanish while packet is out */ 74 void nf_queue_entry_get_refs(struct nf_queue_entry *entry) 75 { 76 struct nf_hook_state *state = &entry->state; 77 78 if (state->in) 79 dev_hold(state->in); 80 if (state->out) 81 dev_hold(state->out); 82 if (state->sk) 83 sock_hold(state->sk); 84 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 85 if (entry->skb->nf_bridge) { 86 struct net_device *physdev; 87 88 physdev = nf_bridge_get_physindev(entry->skb); 89 if (physdev) 90 dev_hold(physdev); 91 physdev = nf_bridge_get_physoutdev(entry->skb); 92 if (physdev) 93 dev_hold(physdev); 94 } 95 #endif 96 } 97 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 98 99 unsigned int nf_queue_nf_hook_drop(struct net *net) 100 { 101 const struct nf_queue_handler *qh; 102 unsigned int count = 0; 103 104 rcu_read_lock(); 105 qh = rcu_dereference(net->nf.queue_handler); 106 if (qh) 107 count = qh->nf_hook_drop(net); 108 rcu_read_unlock(); 109 110 return count; 111 } 112 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop); 113 114 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, 115 const struct nf_hook_entries *entries, 116 unsigned int index, unsigned int queuenum) 117 { 118 int status = -ENOENT; 119 struct nf_queue_entry *entry = NULL; 120 const struct nf_afinfo *afinfo; 121 const struct nf_queue_handler *qh; 122 struct net *net = state->net; 123 124 /* QUEUE == DROP if no one is waiting, to be safe. */ 125 qh = rcu_dereference(net->nf.queue_handler); 126 if (!qh) { 127 status = -ESRCH; 128 goto err; 129 } 130 131 afinfo = nf_get_afinfo(state->pf); 132 if (!afinfo) 133 goto err; 134 135 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 136 if (!entry) { 137 status = -ENOMEM; 138 goto err; 139 } 140 141 *entry = (struct nf_queue_entry) { 142 .skb = skb, 143 .state = *state, 144 .hook_index = index, 145 .size = sizeof(*entry) + afinfo->route_key_size, 146 }; 147 148 nf_queue_entry_get_refs(entry); 149 skb_dst_force(skb); 150 afinfo->saveroute(skb, entry); 151 status = qh->outfn(entry, queuenum); 152 153 if (status < 0) { 154 nf_queue_entry_release_refs(entry); 155 goto err; 156 } 157 158 return 0; 159 160 err: 161 kfree(entry); 162 return status; 163 } 164 165 /* Packets leaving via this function must come back through nf_reinject(). */ 166 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state, 167 const struct nf_hook_entries *entries, unsigned int index, 168 unsigned int verdict) 169 { 170 int ret; 171 172 ret = __nf_queue(skb, state, entries, index, verdict >> NF_VERDICT_QBITS); 173 if (ret < 0) { 174 if (ret == -ESRCH && 175 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 176 return 1; 177 kfree_skb(skb); 178 } 179 180 return 0; 181 } 182 183 static unsigned int nf_iterate(struct sk_buff *skb, 184 struct nf_hook_state *state, 185 const struct nf_hook_entries *hooks, 186 unsigned int *index) 187 { 188 const struct nf_hook_entry *hook; 189 unsigned int verdict, i = *index; 190 191 while (i < hooks->num_hook_entries) { 192 hook = &hooks->hooks[i]; 193 repeat: 194 verdict = nf_hook_entry_hookfn(hook, skb, state); 195 if (verdict != NF_ACCEPT) { 196 if (verdict != NF_REPEAT) 197 return verdict; 198 goto repeat; 199 } 200 i++; 201 } 202 203 *index = i; 204 return NF_ACCEPT; 205 } 206 207 /* Caller must hold rcu read-side lock */ 208 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 209 { 210 const struct nf_hook_entry *hook_entry; 211 const struct nf_hook_entries *hooks; 212 struct sk_buff *skb = entry->skb; 213 const struct nf_afinfo *afinfo; 214 const struct net *net; 215 unsigned int i; 216 int err; 217 u8 pf; 218 219 net = entry->state.net; 220 pf = entry->state.pf; 221 222 hooks = rcu_dereference(net->nf.hooks[pf][entry->state.hook]); 223 224 nf_queue_entry_release_refs(entry); 225 226 i = entry->hook_index; 227 if (WARN_ON_ONCE(i >= hooks->num_hook_entries)) { 228 kfree_skb(skb); 229 kfree(entry); 230 return; 231 } 232 233 hook_entry = &hooks->hooks[i]; 234 235 /* Continue traversal iff userspace said ok... */ 236 if (verdict == NF_REPEAT) 237 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state); 238 239 if (verdict == NF_ACCEPT) { 240 afinfo = nf_get_afinfo(entry->state.pf); 241 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0) 242 verdict = NF_DROP; 243 } 244 245 if (verdict == NF_ACCEPT) { 246 next_hook: 247 ++i; 248 verdict = nf_iterate(skb, &entry->state, hooks, &i); 249 } 250 251 switch (verdict & NF_VERDICT_MASK) { 252 case NF_ACCEPT: 253 case NF_STOP: 254 local_bh_disable(); 255 entry->state.okfn(entry->state.net, entry->state.sk, skb); 256 local_bh_enable(); 257 break; 258 case NF_QUEUE: 259 err = nf_queue(skb, &entry->state, hooks, i, verdict); 260 if (err == 1) 261 goto next_hook; 262 break; 263 case NF_STOLEN: 264 break; 265 default: 266 kfree_skb(skb); 267 } 268 269 kfree(entry); 270 } 271 EXPORT_SYMBOL(nf_reinject); 272