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 void nf_queue_nf_hook_drop(struct net *net) 100 { 101 const struct nf_queue_handler *qh; 102 103 rcu_read_lock(); 104 qh = rcu_dereference(net->nf.queue_handler); 105 if (qh) 106 qh->nf_hook_drop(net); 107 rcu_read_unlock(); 108 } 109 EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop); 110 111 static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, 112 const struct nf_hook_entries *entries, 113 unsigned int index, unsigned int queuenum) 114 { 115 int status = -ENOENT; 116 struct nf_queue_entry *entry = NULL; 117 const struct nf_afinfo *afinfo; 118 const struct nf_queue_handler *qh; 119 struct net *net = state->net; 120 121 /* QUEUE == DROP if no one is waiting, to be safe. */ 122 qh = rcu_dereference(net->nf.queue_handler); 123 if (!qh) { 124 status = -ESRCH; 125 goto err; 126 } 127 128 afinfo = nf_get_afinfo(state->pf); 129 if (!afinfo) 130 goto err; 131 132 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 133 if (!entry) { 134 status = -ENOMEM; 135 goto err; 136 } 137 138 *entry = (struct nf_queue_entry) { 139 .skb = skb, 140 .state = *state, 141 .hook_index = index, 142 .size = sizeof(*entry) + afinfo->route_key_size, 143 }; 144 145 nf_queue_entry_get_refs(entry); 146 skb_dst_force(skb); 147 afinfo->saveroute(skb, entry); 148 status = qh->outfn(entry, queuenum); 149 150 if (status < 0) { 151 nf_queue_entry_release_refs(entry); 152 goto err; 153 } 154 155 return 0; 156 157 err: 158 kfree(entry); 159 return status; 160 } 161 162 /* Packets leaving via this function must come back through nf_reinject(). */ 163 int nf_queue(struct sk_buff *skb, struct nf_hook_state *state, 164 const struct nf_hook_entries *entries, unsigned int index, 165 unsigned int verdict) 166 { 167 int ret; 168 169 ret = __nf_queue(skb, state, entries, index, verdict >> NF_VERDICT_QBITS); 170 if (ret < 0) { 171 if (ret == -ESRCH && 172 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 173 return 1; 174 kfree_skb(skb); 175 } 176 177 return 0; 178 } 179 180 static unsigned int nf_iterate(struct sk_buff *skb, 181 struct nf_hook_state *state, 182 const struct nf_hook_entries *hooks, 183 unsigned int *index) 184 { 185 const struct nf_hook_entry *hook; 186 unsigned int verdict, i = *index; 187 188 while (i < hooks->num_hook_entries) { 189 hook = &hooks->hooks[i]; 190 repeat: 191 verdict = nf_hook_entry_hookfn(hook, skb, state); 192 if (verdict != NF_ACCEPT) { 193 if (verdict != NF_REPEAT) 194 return verdict; 195 goto repeat; 196 } 197 i++; 198 } 199 200 *index = i; 201 return NF_ACCEPT; 202 } 203 204 /* Caller must hold rcu read-side lock */ 205 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 206 { 207 const struct nf_hook_entry *hook_entry; 208 const struct nf_hook_entries *hooks; 209 struct sk_buff *skb = entry->skb; 210 const struct nf_afinfo *afinfo; 211 const struct net *net; 212 unsigned int i; 213 int err; 214 u8 pf; 215 216 net = entry->state.net; 217 pf = entry->state.pf; 218 219 hooks = rcu_dereference(net->nf.hooks[pf][entry->state.hook]); 220 221 nf_queue_entry_release_refs(entry); 222 223 i = entry->hook_index; 224 if (WARN_ON_ONCE(i >= hooks->num_hook_entries)) { 225 kfree_skb(skb); 226 kfree(entry); 227 return; 228 } 229 230 hook_entry = &hooks->hooks[i]; 231 232 /* Continue traversal iff userspace said ok... */ 233 if (verdict == NF_REPEAT) 234 verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state); 235 236 if (verdict == NF_ACCEPT) { 237 afinfo = nf_get_afinfo(entry->state.pf); 238 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0) 239 verdict = NF_DROP; 240 } 241 242 if (verdict == NF_ACCEPT) { 243 next_hook: 244 ++i; 245 verdict = nf_iterate(skb, &entry->state, hooks, &i); 246 } 247 248 switch (verdict & NF_VERDICT_MASK) { 249 case NF_ACCEPT: 250 case NF_STOP: 251 local_bh_disable(); 252 entry->state.okfn(entry->state.net, entry->state.sk, skb); 253 local_bh_enable(); 254 break; 255 case NF_QUEUE: 256 err = nf_queue(skb, &entry->state, hooks, i, verdict); 257 if (err == 1) 258 goto next_hook; 259 break; 260 case NF_STOLEN: 261 break; 262 default: 263 kfree_skb(skb); 264 } 265 266 kfree(entry); 267 } 268 EXPORT_SYMBOL(nf_reinject); 269