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