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 } 73 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); 74 75 /* Bump dev refs so they don't vanish while packet is out */ 76 void nf_queue_entry_get_refs(struct nf_queue_entry *entry) 77 { 78 struct nf_hook_state *state = &entry->state; 79 80 if (state->in) 81 dev_hold(state->in); 82 if (state->out) 83 dev_hold(state->out); 84 if (state->sk) 85 sock_hold(state->sk); 86 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 87 if (entry->skb->nf_bridge) { 88 struct net_device *physdev; 89 90 physdev = nf_bridge_get_physindev(entry->skb); 91 if (physdev) 92 dev_hold(physdev); 93 physdev = nf_bridge_get_physoutdev(entry->skb); 94 if (physdev) 95 dev_hold(physdev); 96 } 97 #endif 98 } 99 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 100 101 void nf_queue_nf_hook_drop(struct net *net, struct nf_hook_ops *ops) 102 { 103 const struct nf_queue_handler *qh; 104 105 rcu_read_lock(); 106 qh = rcu_dereference(queue_handler); 107 if (qh) 108 qh->nf_hook_drop(net, ops); 109 rcu_read_unlock(); 110 } 111 112 /* 113 * Any packet that leaves via this function must come back 114 * through nf_reinject(). 115 */ 116 int nf_queue(struct sk_buff *skb, 117 struct nf_hook_ops *elem, 118 struct nf_hook_state *state, 119 unsigned int queuenum) 120 { 121 int status = -ENOENT; 122 struct nf_queue_entry *entry = NULL; 123 const struct nf_afinfo *afinfo; 124 const struct nf_queue_handler *qh; 125 126 /* QUEUE == DROP if no one is waiting, to be safe. */ 127 qh = rcu_dereference(queue_handler); 128 if (!qh) { 129 status = -ESRCH; 130 goto err; 131 } 132 133 afinfo = nf_get_afinfo(state->pf); 134 if (!afinfo) 135 goto err; 136 137 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 138 if (!entry) { 139 status = -ENOMEM; 140 goto err; 141 } 142 143 *entry = (struct nf_queue_entry) { 144 .skb = skb, 145 .elem = elem, 146 .state = *state, 147 .size = sizeof(*entry) + afinfo->route_key_size, 148 }; 149 150 nf_queue_entry_get_refs(entry); 151 skb_dst_force(skb); 152 afinfo->saveroute(skb, entry); 153 status = qh->outfn(entry, queuenum); 154 155 if (status < 0) { 156 nf_queue_entry_release_refs(entry); 157 goto err; 158 } 159 160 return 0; 161 162 err: 163 kfree(entry); 164 return status; 165 } 166 167 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 168 { 169 struct sk_buff *skb = entry->skb; 170 struct nf_hook_ops *elem = entry->elem; 171 const struct nf_afinfo *afinfo; 172 int err; 173 174 nf_queue_entry_release_refs(entry); 175 176 /* Continue traversal iff userspace said ok... */ 177 if (verdict == NF_REPEAT) 178 verdict = elem->hook(elem->priv, skb, &entry->state); 179 180 if (verdict == NF_ACCEPT) { 181 afinfo = nf_get_afinfo(entry->state.pf); 182 if (!afinfo || afinfo->reroute(entry->state.net, skb, entry) < 0) 183 verdict = NF_DROP; 184 } 185 186 entry->state.thresh = INT_MIN; 187 188 if (verdict == NF_ACCEPT) { 189 next_hook: 190 verdict = nf_iterate(entry->state.hook_list, 191 skb, &entry->state, &elem); 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 err = nf_queue(skb, elem, &entry->state, 203 verdict >> NF_VERDICT_QBITS); 204 if (err < 0) { 205 if (err == -ESRCH && 206 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 207 goto next_hook; 208 kfree_skb(skb); 209 } 210 break; 211 case NF_STOLEN: 212 break; 213 default: 214 kfree_skb(skb); 215 } 216 217 kfree(entry); 218 } 219 EXPORT_SYMBOL(nf_reinject); 220