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, const struct nf_hook_entry *entry) 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, entry); 107 rcu_read_unlock(); 108 } 109 110 /* 111 * Any packet that leaves via this function must come back 112 * through nf_reinject(). 113 */ 114 int nf_queue(struct sk_buff *skb, 115 struct nf_hook_state *state, 116 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 .size = sizeof(*entry) + afinfo->route_key_size, 145 }; 146 147 nf_queue_entry_get_refs(entry); 148 skb_dst_force(skb); 149 afinfo->saveroute(skb, entry); 150 status = qh->outfn(entry, queuenum); 151 152 if (status < 0) { 153 nf_queue_entry_release_refs(entry); 154 goto err; 155 } 156 157 return 0; 158 159 err: 160 kfree(entry); 161 return status; 162 } 163 164 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 165 { 166 struct nf_hook_entry *hook_entry; 167 struct sk_buff *skb = entry->skb; 168 const struct nf_afinfo *afinfo; 169 struct nf_hook_ops *elem; 170 int err; 171 172 hook_entry = rcu_dereference(entry->state.hook_entries); 173 elem = &hook_entry->ops; 174 175 nf_queue_entry_release_refs(entry); 176 177 /* Continue traversal iff userspace said ok... */ 178 if (verdict == NF_REPEAT) 179 verdict = elem->hook(elem->priv, skb, &entry->state); 180 181 if (verdict == NF_ACCEPT) { 182 afinfo = nf_get_afinfo(entry->state.pf); 183 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0) 184 verdict = NF_DROP; 185 } 186 187 entry->state.thresh = INT_MIN; 188 189 if (verdict == NF_ACCEPT) { 190 next_hook: 191 verdict = nf_iterate(skb, &entry->state, &hook_entry); 192 } 193 194 switch (verdict & NF_VERDICT_MASK) { 195 case NF_ACCEPT: 196 case NF_STOP: 197 local_bh_disable(); 198 entry->state.okfn(entry->state.net, entry->state.sk, skb); 199 local_bh_enable(); 200 break; 201 case NF_QUEUE: 202 RCU_INIT_POINTER(entry->state.hook_entries, hook_entry); 203 err = nf_queue(skb, &entry->state, 204 verdict >> NF_VERDICT_QBITS); 205 if (err < 0) { 206 if (err == -ESRCH && 207 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 208 goto next_hook; 209 kfree_skb(skb); 210 } 211 break; 212 case NF_STOLEN: 213 break; 214 default: 215 kfree_skb(skb); 216 } 217 218 kfree(entry); 219 } 220 EXPORT_SYMBOL(nf_reinject); 221