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 static const struct nf_queue_handler __rcu *queue_handler __read_mostly; 30 31 /* return EBUSY when somebody else is registered, return EEXIST if the 32 * same handler is registered, return 0 in case of success. */ 33 void nf_register_queue_handler(const struct nf_queue_handler *qh) 34 { 35 /* should never happen, we only have one queueing backend in kernel */ 36 WARN_ON(rcu_access_pointer(queue_handler)); 37 rcu_assign_pointer(queue_handler, qh); 38 } 39 EXPORT_SYMBOL(nf_register_queue_handler); 40 41 /* The caller must flush their queue before this */ 42 void nf_unregister_queue_handler(void) 43 { 44 RCU_INIT_POINTER(queue_handler, NULL); 45 synchronize_rcu(); 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 /* Drop reference to owner of hook which queued us. */ 73 module_put(entry->elem->owner); 74 } 75 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); 76 77 /* Bump dev refs so they don't vanish while packet is out */ 78 bool nf_queue_entry_get_refs(struct nf_queue_entry *entry) 79 { 80 struct nf_hook_state *state = &entry->state; 81 82 if (!try_module_get(entry->elem->owner)) 83 return false; 84 85 if (state->in) 86 dev_hold(state->in); 87 if (state->out) 88 dev_hold(state->out); 89 if (state->sk) 90 sock_hold(state->sk); 91 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 92 if (entry->skb->nf_bridge) { 93 struct net_device *physdev; 94 95 physdev = nf_bridge_get_physindev(entry->skb); 96 if (physdev) 97 dev_hold(physdev); 98 physdev = nf_bridge_get_physoutdev(entry->skb); 99 if (physdev) 100 dev_hold(physdev); 101 } 102 #endif 103 104 return true; 105 } 106 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 107 108 void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops) 109 { 110 const struct nf_queue_handler *qh; 111 112 rcu_read_lock(); 113 qh = rcu_dereference(queue_handler); 114 if (qh) 115 qh->nf_hook_drop(net, ops); 116 rcu_read_unlock(); 117 } 118 119 /* 120 * Any packet that leaves via this function must come back 121 * through nf_reinject(). 122 */ 123 int nf_queue(struct sk_buff *skb, 124 struct nf_hook_ops *elem, 125 struct nf_hook_state *state, 126 unsigned int queuenum) 127 { 128 int status = -ENOENT; 129 struct nf_queue_entry *entry = NULL; 130 const struct nf_afinfo *afinfo; 131 const struct nf_queue_handler *qh; 132 133 /* QUEUE == DROP if no one is waiting, to be safe. */ 134 rcu_read_lock(); 135 136 qh = rcu_dereference(queue_handler); 137 if (!qh) { 138 status = -ESRCH; 139 goto err_unlock; 140 } 141 142 afinfo = nf_get_afinfo(state->pf); 143 if (!afinfo) 144 goto err_unlock; 145 146 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 147 if (!entry) { 148 status = -ENOMEM; 149 goto err_unlock; 150 } 151 152 *entry = (struct nf_queue_entry) { 153 .skb = skb, 154 .elem = elem, 155 .state = *state, 156 .size = sizeof(*entry) + afinfo->route_key_size, 157 }; 158 159 if (!nf_queue_entry_get_refs(entry)) { 160 status = -ECANCELED; 161 goto err_unlock; 162 } 163 skb_dst_force(skb); 164 afinfo->saveroute(skb, entry); 165 status = qh->outfn(entry, queuenum); 166 167 rcu_read_unlock(); 168 169 if (status < 0) { 170 nf_queue_entry_release_refs(entry); 171 goto err; 172 } 173 174 return 0; 175 176 err_unlock: 177 rcu_read_unlock(); 178 err: 179 kfree(entry); 180 return status; 181 } 182 183 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 184 { 185 struct sk_buff *skb = entry->skb; 186 struct nf_hook_ops *elem = entry->elem; 187 const struct nf_afinfo *afinfo; 188 int err; 189 190 rcu_read_lock(); 191 192 nf_queue_entry_release_refs(entry); 193 194 /* Continue traversal iff userspace said ok... */ 195 if (verdict == NF_REPEAT) { 196 elem = list_entry(elem->list.prev, struct nf_hook_ops, list); 197 verdict = NF_ACCEPT; 198 } 199 200 if (verdict == NF_ACCEPT) { 201 afinfo = nf_get_afinfo(entry->state.pf); 202 if (!afinfo || afinfo->reroute(skb, entry) < 0) 203 verdict = NF_DROP; 204 } 205 206 entry->state.thresh = INT_MIN; 207 208 if (verdict == NF_ACCEPT) { 209 next_hook: 210 verdict = nf_iterate(entry->state.hook_list, 211 skb, &entry->state, &elem); 212 } 213 214 switch (verdict & NF_VERDICT_MASK) { 215 case NF_ACCEPT: 216 case NF_STOP: 217 local_bh_disable(); 218 entry->state.okfn(entry->state.sk, skb); 219 local_bh_enable(); 220 break; 221 case NF_QUEUE: 222 err = nf_queue(skb, elem, &entry->state, 223 verdict >> NF_VERDICT_QBITS); 224 if (err < 0) { 225 if (err == -ECANCELED) 226 goto next_hook; 227 if (err == -ESRCH && 228 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 229 goto next_hook; 230 kfree_skb(skb); 231 } 232 break; 233 case NF_STOLEN: 234 break; 235 default: 236 kfree_skb(skb); 237 } 238 rcu_read_unlock(); 239 kfree(entry); 240 } 241 EXPORT_SYMBOL(nf_reinject); 242