diff options
Diffstat (limited to 'net/netfilter/nf_queue.c')
| -rw-r--r-- | net/netfilter/nf_queue.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c new file mode 100644 index 000000000..2e88032cd --- /dev/null +++ b/net/netfilter/nf_queue.c @@ -0,0 +1,230 @@ +/* + * Rusty Russell (C)2000 -- This code is GPL. + * Patrick McHardy (c) 2006-2012 + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/proc_fs.h> +#include <linux/skbuff.h> +#include <linux/netfilter.h> +#include <linux/netfilter_bridge.h> +#include <linux/seq_file.h> +#include <linux/rcupdate.h> +#include <net/protocol.h> +#include <net/netfilter/nf_queue.h> +#include <net/dst.h> + +#include "nf_internals.h" + +/* + * Hook for nfnetlink_queue to register its queue handler. + * We do this so that most of the NFQUEUE code can be modular. + * + * Once the queue is registered it must reinject all packets it + * receives, no matter what. + */ +static const struct nf_queue_handler __rcu *queue_handler __read_mostly; + +/* return EBUSY when somebody else is registered, return EEXIST if the + * same handler is registered, return 0 in case of success. */ +void nf_register_queue_handler(const struct nf_queue_handler *qh) +{ + /* should never happen, we only have one queueing backend in kernel */ + WARN_ON(rcu_access_pointer(queue_handler)); + rcu_assign_pointer(queue_handler, qh); +} +EXPORT_SYMBOL(nf_register_queue_handler); + +/* The caller must flush their queue before this */ +void nf_unregister_queue_handler(void) +{ + RCU_INIT_POINTER(queue_handler, NULL); + synchronize_rcu(); +} +EXPORT_SYMBOL(nf_unregister_queue_handler); + +void nf_queue_entry_release_refs(struct nf_queue_entry *entry) +{ + struct nf_hook_state *state = &entry->state; + + /* Release those devices we held, or Alexey will kill me. */ + if (state->in) + dev_put(state->in); + if (state->out) + dev_put(state->out); + if (state->sk) + sock_put(state->sk); +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + if (entry->skb->nf_bridge) { + struct net_device *physdev; + + physdev = nf_bridge_get_physindev(entry->skb); + if (physdev) + dev_put(physdev); + physdev = nf_bridge_get_physoutdev(entry->skb); + if (physdev) + dev_put(physdev); + } +#endif + /* Drop reference to owner of hook which queued us. */ + module_put(entry->elem->owner); +} +EXPORT_SYMBOL_GPL(nf_queue_entry_release_refs); + +/* Bump dev refs so they don't vanish while packet is out */ +bool nf_queue_entry_get_refs(struct nf_queue_entry *entry) +{ + struct nf_hook_state *state = &entry->state; + + if (!try_module_get(entry->elem->owner)) + return false; + + if (state->in) + dev_hold(state->in); + if (state->out) + dev_hold(state->out); + if (state->sk) + sock_hold(state->sk); +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + if (entry->skb->nf_bridge) { + struct net_device *physdev; + + physdev = nf_bridge_get_physindev(entry->skb); + if (physdev) + dev_hold(physdev); + physdev = nf_bridge_get_physoutdev(entry->skb); + if (physdev) + dev_hold(physdev); + } +#endif + + return true; +} +EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); + +/* + * Any packet that leaves via this function must come back + * through nf_reinject(). + */ +int nf_queue(struct sk_buff *skb, + struct nf_hook_ops *elem, + struct nf_hook_state *state, + unsigned int queuenum) +{ + int status = -ENOENT; + struct nf_queue_entry *entry = NULL; + const struct nf_afinfo *afinfo; + const struct nf_queue_handler *qh; + + /* QUEUE == DROP if no one is waiting, to be safe. */ + rcu_read_lock(); + + qh = rcu_dereference(queue_handler); + if (!qh) { + status = -ESRCH; + goto err_unlock; + } + + afinfo = nf_get_afinfo(state->pf); + if (!afinfo) + goto err_unlock; + + entry = kmalloc(sizeof(*entry) + afinfo->route_key_size, GFP_ATOMIC); + if (!entry) { + status = -ENOMEM; + goto err_unlock; + } + + *entry = (struct nf_queue_entry) { + .skb = skb, + .elem = elem, + .state = *state, + .size = sizeof(*entry) + afinfo->route_key_size, + }; + + if (!nf_queue_entry_get_refs(entry)) { + status = -ECANCELED; + goto err_unlock; + } + skb_dst_force(skb); + afinfo->saveroute(skb, entry); + status = qh->outfn(entry, queuenum); + + rcu_read_unlock(); + + if (status < 0) { + nf_queue_entry_release_refs(entry); + goto err; + } + + return 0; + +err_unlock: + rcu_read_unlock(); +err: + kfree(entry); + return status; +} + +void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) +{ + struct sk_buff *skb = entry->skb; + struct nf_hook_ops *elem = entry->elem; + const struct nf_afinfo *afinfo; + int err; + + rcu_read_lock(); + + nf_queue_entry_release_refs(entry); + + /* Continue traversal iff userspace said ok... */ + if (verdict == NF_REPEAT) { + elem = list_entry(elem->list.prev, struct nf_hook_ops, list); + verdict = NF_ACCEPT; + } + + if (verdict == NF_ACCEPT) { + afinfo = nf_get_afinfo(entry->state.pf); + if (!afinfo || afinfo->reroute(skb, entry) < 0) + verdict = NF_DROP; + } + + entry->state.thresh = INT_MIN; + + if (verdict == NF_ACCEPT) { + next_hook: + verdict = nf_iterate(&nf_hooks[entry->state.pf][entry->state.hook], + skb, &entry->state, &elem); + } + + switch (verdict & NF_VERDICT_MASK) { + case NF_ACCEPT: + case NF_STOP: + local_bh_disable(); + entry->state.okfn(entry->state.sk, skb); + local_bh_enable(); + break; + case NF_QUEUE: + err = nf_queue(skb, elem, &entry->state, + verdict >> NF_VERDICT_QBITS); + if (err < 0) { + if (err == -ECANCELED) + goto next_hook; + if (err == -ESRCH && + (verdict & NF_VERDICT_FLAG_QUEUE_BYPASS)) + goto next_hook; + kfree_skb(skb); + } + break; + case NF_STOLEN: + break; + default: + kfree_skb(skb); + } + rcu_read_unlock(); + kfree(entry); +} +EXPORT_SYMBOL(nf_reinject); |