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/seq_file.h> 14 #include <linux/rcupdate.h> 15 #include <net/protocol.h> 16 #include <net/netfilter/nf_queue.h> 17 #include <net/dst.h> 18 19 #include "nf_internals.h" 20 21 /* 22 * Hook for nfnetlink_queue to register its queue handler. 23 * We do this so that most of the NFQUEUE code can be modular. 24 * 25 * Once the queue is registered it must reinject all packets it 26 * receives, no matter what. 27 */ 28 static const struct nf_queue_handler __rcu *queue_handler __read_mostly; 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(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(queue_handler)); 36 rcu_assign_pointer(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(void) 42 { 43 RCU_INIT_POINTER(queue_handler, NULL); 44 synchronize_rcu(); 45 } 46 EXPORT_SYMBOL(nf_unregister_queue_handler); 47 48 void nf_queue_entry_release_refs(struct nf_queue_entry *entry) 49 { 50 /* Release those devices we held, or Alexey will kill me. */ 51 if (entry->indev) 52 dev_put(entry->indev); 53 if (entry->outdev) 54 dev_put(entry->outdev); 55 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 56 if (entry->skb->nf_bridge) { 57 struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge; 58 59 if (nf_bridge->physindev) 60 dev_put(nf_bridge->physindev); 61 if (nf_bridge->physoutdev) 62 dev_put(nf_bridge->physoutdev); 63 } 64 #endif 65 /* Drop reference to owner of hook which queued us. */ 66 module_put(entry->elem->owner); 67 } 68 EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); 69 70 /* Bump dev refs so they don't vanish while packet is out */ 71 bool nf_queue_entry_get_refs(struct nf_queue_entry *entry) 72 { 73 if (!try_module_get(entry->elem->owner)) 74 return false; 75 76 if (entry->indev) 77 dev_hold(entry->indev); 78 if (entry->outdev) 79 dev_hold(entry->outdev); 80 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) 81 if (entry->skb->nf_bridge) { 82 struct nf_bridge_info *nf_bridge = entry->skb->nf_bridge; 83 struct net_device *physdev; 84 85 physdev = nf_bridge->physindev; 86 if (physdev) 87 dev_hold(physdev); 88 physdev = nf_bridge->physoutdev; 89 if (physdev) 90 dev_hold(physdev); 91 } 92 #endif 93 94 return true; 95 } 96 EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); 97 98 /* 99 * Any packet that leaves via this function must come back 100 * through nf_reinject(). 101 */ 102 int nf_queue(struct sk_buff *skb, 103 struct nf_hook_ops *elem, 104 u_int8_t pf, unsigned int hook, 105 struct net_device *indev, 106 struct net_device *outdev, 107 int (*okfn)(struct sk_buff *), 108 unsigned int queuenum) 109 { 110 int status = -ENOENT; 111 struct nf_queue_entry *entry = NULL; 112 const struct nf_afinfo *afinfo; 113 const struct nf_queue_handler *qh; 114 115 /* QUEUE == DROP if no one is waiting, to be safe. */ 116 rcu_read_lock(); 117 118 qh = rcu_dereference(queue_handler); 119 if (!qh) { 120 status = -ESRCH; 121 goto err_unlock; 122 } 123 124 afinfo = nf_get_afinfo(pf); 125 if (!afinfo) 126 goto err_unlock; 127 128 entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); 129 if (!entry) { 130 status = -ENOMEM; 131 goto err_unlock; 132 } 133 134 *entry = (struct nf_queue_entry) { 135 .skb = skb, 136 .elem = elem, 137 .pf = pf, 138 .hook = hook, 139 .indev = indev, 140 .outdev = outdev, 141 .okfn = okfn, 142 .size = sizeof(*entry) + afinfo->route_key_size, 143 }; 144 145 if (!nf_queue_entry_get_refs(entry)) { 146 status = -ECANCELED; 147 goto err_unlock; 148 } 149 skb_dst_force(skb); 150 afinfo->saveroute(skb, entry); 151 status = qh->outfn(entry, queuenum); 152 153 rcu_read_unlock(); 154 155 if (status < 0) { 156 nf_queue_entry_release_refs(entry); 157 goto err; 158 } 159 160 return 0; 161 162 err_unlock: 163 rcu_read_unlock(); 164 err: 165 kfree(entry); 166 return status; 167 } 168 169 void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) 170 { 171 struct sk_buff *skb = entry->skb; 172 struct nf_hook_ops *elem = entry->elem; 173 const struct nf_afinfo *afinfo; 174 int err; 175 176 rcu_read_lock(); 177 178 nf_queue_entry_release_refs(entry); 179 180 /* Continue traversal iff userspace said ok... */ 181 if (verdict == NF_REPEAT) { 182 elem = list_entry(elem->list.prev, struct nf_hook_ops, list); 183 verdict = NF_ACCEPT; 184 } 185 186 if (verdict == NF_ACCEPT) { 187 afinfo = nf_get_afinfo(entry->pf); 188 if (!afinfo || afinfo->reroute(skb, entry) < 0) 189 verdict = NF_DROP; 190 } 191 192 if (verdict == NF_ACCEPT) { 193 next_hook: 194 verdict = nf_iterate(&nf_hooks[entry->pf][entry->hook], 195 skb, entry->hook, 196 entry->indev, entry->outdev, &elem, 197 entry->okfn, INT_MIN); 198 } 199 200 switch (verdict & NF_VERDICT_MASK) { 201 case NF_ACCEPT: 202 case NF_STOP: 203 local_bh_disable(); 204 entry->okfn(skb); 205 local_bh_enable(); 206 break; 207 case NF_QUEUE: 208 err = nf_queue(skb, elem, entry->pf, entry->hook, 209 entry->indev, entry->outdev, entry->okfn, 210 verdict >> NF_VERDICT_QBITS); 211 if (err < 0) { 212 if (err == -ECANCELED) 213 goto next_hook; 214 if (err == -ESRCH && 215 (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) 216 goto next_hook; 217 kfree_skb(skb); 218 } 219 break; 220 case NF_STOLEN: 221 break; 222 default: 223 kfree_skb(skb); 224 } 225 rcu_read_unlock(); 226 kfree(entry); 227 } 228 EXPORT_SYMBOL(nf_reinject); 229