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, struct nf_hook_ops *ops) 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, ops); 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_ops *elem, 116 struct nf_hook_state *state, 117 unsigned int queuenum) 118 { 119 int status = -ENOENT; 120 struct nf_queue_entry *entry = NULL; 121 const struct nf_afinfo *afinfo; 122 const struct nf_queue_handler *qh; 123 struct net *net = state->net; 124 125 /* QUEUE == DROP if no one is waiting, to be safe. */ 126 qh = rcu_dereference(net->nf.queue_handler); 127 if (!qh) { 128 status = -ESRCH; 129 goto err; 130 } 131 132 afinfo = nf_get_afinfo(state->pf); 133 if (!afinfo) 134 goto err; 135 136 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 137 if (!entry) { 138 status = -ENOMEM; 139 goto err; 140 } 141 142 *entry = (struct nf_queue_entry) { 143 .skb = skb, 144 .elem = elem, 145 .state = *state, 146 .size = sizeof(*entry) + afinfo->route_key_size, 147 }; 148 149 nf_queue_entry_get_refs(entry); 150 skb_dst_force(skb); 151 afinfo->saveroute(skb, entry); 152 status = qh->outfn(entry, queuenum); 153 154 if (status < 0) { 155 nf_queue_entry_release_refs(entry); 156 goto err; 157 } 158 159 return 0; 160 161 err: 162 kfree(entry); 163 return status; 164 } 165 166 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 167 { 168 struct sk_buff *skb = entry->skb; 169 struct nf_hook_ops *elem = entry->elem; 170 const struct nf_afinfo *afinfo; 171 int err; 172 173 nf_queue_entry_release_refs(entry); 174 175 /* Continue traversal iff userspace said ok... */ 176 if (verdict == NF_REPEAT) 177 verdict = elem->hook(elem->priv, skb, &entry->state); 178 179 if (verdict == NF_ACCEPT) { 180 afinfo = nf_get_afinfo(entry->state.pf); 181 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0) 182 verdict = NF_DROP; 183 } 184 185 entry->state.thresh = INT_MIN; 186 187 if (verdict == NF_ACCEPT) { 188 next_hook: 189 verdict = nf_iterate(entry->state.hook_list, 190 skb, &entry->state, &elem); 191 } 192 193 switch (verdict & NF_VERDICT_MASK) { 194 case NF_ACCEPT: 195 case NF_STOP: 196 local_bh_disable(); 197 entry->state.okfn(entry->state.net, entry->state.sk, skb); 198 local_bh_enable(); 199 break; 200 case NF_QUEUE: 201 err = nf_queue(skb, elem, &entry->state, 202 verdict >> NF_VERDICT_QBITS); 203 if (err < 0) { 204 if (err == -ESRCH && 205 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 206 goto next_hook; 207 kfree_skb(skb); 208 } 209 break; 210 case NF_STOLEN: 211 break; 212 default: 213 kfree_skb(skb); 214 } 215 216 kfree(entry); 217 } 218 EXPORT_SYMBOL(nf_reinject); 219