nf_queue.c
/*
* 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_ipv4.h>
#include <linux/netfilter_ipv6.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"
static const struct nf_queue_handler __rcu *nf_queue_handler;
/*
* 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.
*/
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(nf_queue_handler));
rcu_assign_pointer(nf_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(nf_queue_handler, NULL);
}
EXPORT_SYMBOL(nf_unregister_queue_handler);
static void nf_queue_sock_put(struct sock *sk)
{
#ifdef CONFIG_INET
sock_gen_put(sk);
#else
sock_put(sk);
#endif
}
static 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. */
dev_put(state->in);
dev_put(state->out);
if (state->sk)
nf_queue_sock_put(state->sk);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
dev_put(entry->physin);
dev_put(entry->physout);
#endif
}
void nf_queue_entry_free(struct nf_queue_entry *entry)
{
nf_queue_entry_release_refs(entry);
kfree(entry);
}
EXPORT_SYMBOL_GPL(nf_queue_entry_free);
static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
{
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
const struct sk_buff *skb = entry->skb;
struct nf_bridge_info *nf_bridge;
nf_bridge = nf_bridge_info_get(skb);
if (nf_bridge) {
entry->physin = nf_bridge_get_physindev(skb);
entry->physout = nf_bridge_get_physoutdev(skb);
} else {
entry->physin = NULL;
entry->physout = NULL;
}
#endif
}
/* 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 (state->sk && !refcount_inc_not_zero(&state->sk->sk_refcnt))
return false;
dev_hold(state->in);
dev_hold(state->out);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
dev_hold(entry->physin);
dev_hold(entry->physout);
#endif
return true;
}
EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
void nf_queue_nf_hook_drop(struct net *net)
{
const struct nf_queue_handler *qh;
rcu_read_lock();
qh = rcu_dereference(nf_queue_handler);
if (qh)
qh->nf_hook_drop(net);
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(nf_queue_nf_hook_drop);
static void nf_ip_saveroute(const struct sk_buff *skb,
struct nf_queue_entry *entry)
{
struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
if (entry->state.hook == NF_INET_LOCAL_OUT) {
const struct iphdr *iph = ip_hdr(skb);
rt_info->tos = iph->tos;
rt_info->daddr = iph->daddr;
rt_info->saddr = iph->saddr;
rt_info->mark = skb->mark;
}
}
static void nf_ip6_saveroute(const struct sk_buff *skb,
struct nf_queue_entry *entry)
{
struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
if (entry->state.hook == NF_INET_LOCAL_OUT) {
const struct ipv6hdr *iph = ipv6_hdr(skb);
rt_info->daddr = iph->daddr;
rt_info->saddr = iph->saddr;
rt_info->mark = skb->mark;
}
}
static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
unsigned int index, unsigned int queuenum)
{
struct nf_queue_entry *entry = NULL;
const struct nf_queue_handler *qh;
unsigned int route_key_size;
int status;
/* QUEUE == DROP if no one is waiting, to be safe. */
qh = rcu_dereference(nf_queue_handler);
if (!qh)
return -ESRCH;
switch (state->pf) {
case AF_INET:
route_key_size = sizeof(struct ip_rt_info);
break;
case AF_INET6:
route_key_size = sizeof(struct ip6_rt_info);
break;
default:
route_key_size = 0;
break;
}
if (skb_sk_is_prefetched(skb)) {
struct sock *sk = skb->sk;
if (!sk_is_refcounted(sk)) {
if (!refcount_inc_not_zero(&sk->sk_refcnt))
return -ENOTCONN;
/* drop refcount on skb_orphan */
skb->destructor = sock_edemux;
}
}
entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC);
if (!entry)
return -ENOMEM;
if (skb_dst(skb) && !skb_dst_force(skb)) {
kfree(entry);
return -ENETDOWN;
}
*entry = (struct nf_queue_entry) {
.skb = skb,
.state = *state,
.hook_index = index,
.size = sizeof(*entry) + route_key_size,
};
__nf_queue_entry_init_physdevs(entry);
if (!nf_queue_entry_get_refs(entry)) {
kfree(entry);
return -ENOTCONN;
}
switch (entry->state.pf) {
case AF_INET:
nf_ip_saveroute(skb, entry);
break;
case AF_INET6:
nf_ip6_saveroute(skb, entry);
break;
}
status = qh->outfn(entry, queuenum);
if (status < 0) {
nf_queue_entry_free(entry);
return status;
}
return 0;
}
/* Packets leaving via this function must come back through nf_reinject(). */
int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
unsigned int index, unsigned int verdict)
{
int ret;
ret = __nf_queue(skb, state, index, verdict >> NF_VERDICT_QBITS);
if (ret < 0) {
if (ret == -ESRCH &&
(verdict & NF_VERDICT_FLAG_QUEUE_BYPASS))
return 1;
kfree_skb(skb);
}
return 0;
}
EXPORT_SYMBOL_GPL(nf_queue);
static unsigned int nf_iterate(struct sk_buff *skb,
struct nf_hook_state *state,
const struct nf_hook_entries *hooks,
unsigned int *index)
{
const struct nf_hook_entry *hook;
unsigned int verdict, i = *index;
while (i < hooks->num_hook_entries) {
hook = &hooks->hooks[i];
repeat:
verdict = nf_hook_entry_hookfn(hook, skb, state);
if (verdict != NF_ACCEPT) {
*index = i;
if (verdict != NF_REPEAT)
return verdict;
goto repeat;
}
i++;
}
*index = i;
return NF_ACCEPT;
}
static struct nf_hook_entries *nf_hook_entries_head(const struct net *net, u8 pf, u8 hooknum)
{
switch (pf) {
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
case NFPROTO_BRIDGE:
return rcu_dereference(net->nf.hooks_bridge[hooknum]);
#endif
case NFPROTO_IPV4:
return rcu_dereference(net->nf.hooks_ipv4[hooknum]);
case NFPROTO_IPV6:
return rcu_dereference(net->nf.hooks_ipv6[hooknum]);
default:
WARN_ON_ONCE(1);
return NULL;
}
return NULL;
}
/* Caller must hold rcu read-side lock */
void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
{
const struct nf_hook_entry *hook_entry;
const struct nf_hook_entries *hooks;
struct sk_buff *skb = entry->skb;
const struct net *net;
unsigned int i;
int err;
u8 pf;
net = entry->state.net;
pf = entry->state.pf;
hooks = nf_hook_entries_head(net, pf, entry->state.hook);
i = entry->hook_index;
if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) {
kfree_skb(skb);
nf_queue_entry_free(entry);
return;
}
hook_entry = &hooks->hooks[i];
/* Continue traversal iff userspace said ok... */
if (verdict == NF_REPEAT)
verdict = nf_hook_entry_hookfn(hook_entry, skb, &entry->state);
if (verdict == NF_ACCEPT) {
if (nf_reroute(skb, entry) < 0)
verdict = NF_DROP;
}
if (verdict == NF_ACCEPT) {
next_hook:
++i;
verdict = nf_iterate(skb, &entry->state, hooks, &i);
}
switch (verdict & NF_VERDICT_MASK) {
case NF_ACCEPT:
case NF_STOP:
local_bh_disable();
entry->state.okfn(entry->state.net, entry->state.sk, skb);
local_bh_enable();
break;
case NF_QUEUE:
err = nf_queue(skb, &entry->state, i, verdict);
if (err == 1)
goto next_hook;
break;
case NF_STOLEN:
break;
default:
kfree_skb(skb);
}
nf_queue_entry_free(entry);
}
EXPORT_SYMBOL(nf_reinject);