blob: 52cd2901a097b3b468f1107d9d870260aaff11e3 [file] [log] [blame]
/* netfilter.c: look after the filters for various protocols.
* Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
*
* Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
* way.
*
* Rusty Russell (C)2000 -- This code is GPL.
* Patrick McHardy (c) 2006-2012
*/
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <net/protocol.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/if.h>
#include <linux/netdevice.h>
#include <linux/netfilter_ipv6.h>
#include <linux/inetdevice.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include "nf_internals.h"
static DEFINE_MUTEX(afinfo_mutex);
const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
EXPORT_SYMBOL(nf_afinfo);
const struct nf_ipv6_ops __rcu *nf_ipv6_ops __read_mostly;
EXPORT_SYMBOL_GPL(nf_ipv6_ops);
DEFINE_PER_CPU(bool, nf_skb_duplicated);
EXPORT_SYMBOL_GPL(nf_skb_duplicated);
int nf_register_afinfo(const struct nf_afinfo *afinfo)
{
mutex_lock(&afinfo_mutex);
RCU_INIT_POINTER(nf_afinfo[afinfo->family], afinfo);
mutex_unlock(&afinfo_mutex);
return 0;
}
EXPORT_SYMBOL_GPL(nf_register_afinfo);
void nf_unregister_afinfo(const struct nf_afinfo *afinfo)
{
mutex_lock(&afinfo_mutex);
RCU_INIT_POINTER(nf_afinfo[afinfo->family], NULL);
mutex_unlock(&afinfo_mutex);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
#ifdef HAVE_JUMP_LABEL
struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
EXPORT_SYMBOL(nf_hooks_needed);
#endif
static DEFINE_MUTEX(nf_hook_mutex);
/* max hooks per family/hooknum */
#define MAX_HOOK_COUNT 1024
#define nf_entry_dereference(e) \
rcu_dereference_protected(e, lockdep_is_held(&nf_hook_mutex))
static struct nf_hook_entries *allocate_hook_entries_size(u16 num)
{
struct nf_hook_entries *e;
size_t alloc = sizeof(*e) +
sizeof(struct nf_hook_entry) * num +
sizeof(struct nf_hook_ops *) * num;
if (num == 0)
return NULL;
e = kvzalloc(alloc, GFP_KERNEL);
if (e)
e->num_hook_entries = num;
return e;
}
static unsigned int accept_all(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
return NF_ACCEPT; /* ACCEPT makes nf_hook_slow call next hook */
}
static const struct nf_hook_ops dummy_ops = {
.hook = accept_all,
.priority = INT_MIN,
};
static struct nf_hook_entries *
nf_hook_entries_grow(const struct nf_hook_entries *old,
const struct nf_hook_ops *reg)
{
unsigned int i, alloc_entries, nhooks, old_entries;
struct nf_hook_ops **orig_ops = NULL;
struct nf_hook_ops **new_ops;
struct nf_hook_entries *new;
bool inserted = false;
alloc_entries = 1;
old_entries = old ? old->num_hook_entries : 0;
if (old) {
orig_ops = nf_hook_entries_get_hook_ops(old);
for (i = 0; i < old_entries; i++) {
if (orig_ops[i] != &dummy_ops)
alloc_entries++;
}
}
if (alloc_entries > MAX_HOOK_COUNT)
return ERR_PTR(-E2BIG);
new = allocate_hook_entries_size(alloc_entries);
if (!new)
return ERR_PTR(-ENOMEM);
new_ops = nf_hook_entries_get_hook_ops(new);
i = 0;
nhooks = 0;
while (i < old_entries) {
if (orig_ops[i] == &dummy_ops) {
++i;
continue;
}
if (inserted || reg->priority > orig_ops[i]->priority) {
new_ops[nhooks] = (void *)orig_ops[i];
new->hooks[nhooks] = old->hooks[i];
i++;
} else {
new_ops[nhooks] = (void *)reg;
new->hooks[nhooks].hook = reg->hook;
new->hooks[nhooks].priv = reg->priv;
inserted = true;
}
nhooks++;
}
if (!inserted) {
new_ops[nhooks] = (void *)reg;
new->hooks[nhooks].hook = reg->hook;
new->hooks[nhooks].priv = reg->priv;
}
return new;
}
static void hooks_validate(const struct nf_hook_entries *hooks)
{
#ifdef CONFIG_DEBUG_KERNEL
struct nf_hook_ops **orig_ops;
int prio = INT_MIN;
size_t i = 0;
orig_ops = nf_hook_entries_get_hook_ops(hooks);
for (i = 0; i < hooks->num_hook_entries; i++) {
if (orig_ops[i] == &dummy_ops)
continue;
WARN_ON(orig_ops[i]->priority < prio);
if (orig_ops[i]->priority > prio)
prio = orig_ops[i]->priority;
}
#endif
}
/*
* __nf_hook_entries_try_shrink - try to shrink hook array
*
* @pp -- location of hook blob
*
* Hook unregistration must always succeed, so to-be-removed hooks
* are replaced by a dummy one that will just move to next hook.
*
* This counts the current dummy hooks, attempts to allocate new blob,
* copies the live hooks, then replaces and discards old one.
*
* return values:
*
* Returns address to free, or NULL.
*/
static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu **pp)
{
struct nf_hook_entries *old, *new = NULL;
unsigned int i, j, skip = 0, hook_entries;
struct nf_hook_ops **orig_ops;
struct nf_hook_ops **new_ops;
old = nf_entry_dereference(*pp);
if (WARN_ON_ONCE(!old))
return NULL;
orig_ops = nf_hook_entries_get_hook_ops(old);
for (i = 0; i < old->num_hook_entries; i++) {
if (orig_ops[i] == &dummy_ops)
skip++;
}
/* if skip == hook_entries all hooks have been removed */
hook_entries = old->num_hook_entries;
if (skip == hook_entries)
goto out_assign;
if (skip == 0)
return NULL;
hook_entries -= skip;
new = allocate_hook_entries_size(hook_entries);
if (!new)
return NULL;
new_ops = nf_hook_entries_get_hook_ops(new);
for (i = 0, j = 0; i < old->num_hook_entries; i++) {
if (orig_ops[i] == &dummy_ops)
continue;
new->hooks[j] = old->hooks[i];
new_ops[j] = (void *)orig_ops[i];
j++;
}
hooks_validate(new);
out_assign:
rcu_assign_pointer(*pp, new);
return old;
}
static struct nf_hook_entries __rcu **nf_hook_entry_head(struct net *net, const struct nf_hook_ops *reg)
{
if (reg->pf != NFPROTO_NETDEV)
return net->nf.hooks[reg->pf]+reg->hooknum;
#ifdef CONFIG_NETFILTER_INGRESS
if (reg->hooknum == NF_NETDEV_INGRESS) {
if (reg->dev && dev_net(reg->dev) == net)
return &reg->dev->nf_hooks_ingress;
}
#endif
WARN_ON_ONCE(1);
return NULL;
}
int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
struct nf_hook_entries *p, *new_hooks;
struct nf_hook_entries __rcu **pp;
if (reg->pf == NFPROTO_NETDEV) {
#ifndef CONFIG_NETFILTER_INGRESS
if (reg->hooknum == NF_NETDEV_INGRESS)
return -EOPNOTSUPP;
#endif
if (reg->hooknum != NF_NETDEV_INGRESS ||
!reg->dev || dev_net(reg->dev) != net)
return -EINVAL;
}
pp = nf_hook_entry_head(net, reg);
if (!pp)
return -EINVAL;
mutex_lock(&nf_hook_mutex);
p = nf_entry_dereference(*pp);
new_hooks = nf_hook_entries_grow(p, reg);
if (!IS_ERR(new_hooks))
rcu_assign_pointer(*pp, new_hooks);
mutex_unlock(&nf_hook_mutex);
if (IS_ERR(new_hooks))
return PTR_ERR(new_hooks);
hooks_validate(new_hooks);
#ifdef CONFIG_NETFILTER_INGRESS
if (reg->pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
net_inc_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
synchronize_net();
BUG_ON(p == new_hooks);
kvfree(p);
return 0;
}
EXPORT_SYMBOL(nf_register_net_hook);
/*
* __nf_unregister_net_hook - remove a hook from blob
*
* @oldp: current address of hook blob
* @unreg: hook to unregister
*
* This cannot fail, hook unregistration must always succeed.
* Therefore replace the to-be-removed hook with a dummy hook.
*/
static void __nf_unregister_net_hook(struct nf_hook_entries *old,
const struct nf_hook_ops *unreg)
{
struct nf_hook_ops **orig_ops;
bool found = false;
unsigned int i;
orig_ops = nf_hook_entries_get_hook_ops(old);
for (i = 0; i < old->num_hook_entries; i++) {
if (orig_ops[i] != unreg)
continue;
WRITE_ONCE(old->hooks[i].hook, accept_all);
WRITE_ONCE(orig_ops[i], &dummy_ops);
found = true;
break;
}
if (found) {
#ifdef CONFIG_NETFILTER_INGRESS
if (unreg->pf == NFPROTO_NETDEV && unreg->hooknum == NF_NETDEV_INGRESS)
net_dec_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_dec(&nf_hooks_needed[unreg->pf][unreg->hooknum]);
#endif
} else {
WARN_ONCE(1, "hook not found, pf %d num %d", unreg->pf, unreg->hooknum);
}
}
void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
struct nf_hook_entries __rcu **pp;
struct nf_hook_entries *p;
unsigned int nfq;
pp = nf_hook_entry_head(net, reg);
if (!pp)
return;
mutex_lock(&nf_hook_mutex);
p = nf_entry_dereference(*pp);
if (WARN_ON_ONCE(!p)) {
mutex_unlock(&nf_hook_mutex);
return;
}
__nf_unregister_net_hook(p, reg);
p = __nf_hook_entries_try_shrink(pp);
mutex_unlock(&nf_hook_mutex);
if (!p)
return;
synchronize_net();
/* other cpu might still process nfqueue verdict that used reg */
nfq = nf_queue_nf_hook_drop(net);
if (nfq)
synchronize_net();
kvfree(p);
}
EXPORT_SYMBOL(nf_unregister_net_hook);
int nf_register_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int n)
{
unsigned int i;
int err = 0;
for (i = 0; i < n; i++) {
err = nf_register_net_hook(net, &reg[i]);
if (err)
goto err;
}
return err;
err:
if (i > 0)
nf_unregister_net_hooks(net, reg, i);
return err;
}
EXPORT_SYMBOL(nf_register_net_hooks);
void nf_unregister_net_hooks(struct net *net, const struct nf_hook_ops *reg,
unsigned int hookcount)
{
struct nf_hook_entries *to_free[16], *p;
struct nf_hook_entries __rcu **pp;
unsigned int i, j, n;
mutex_lock(&nf_hook_mutex);
for (i = 0; i < hookcount; i++) {
pp = nf_hook_entry_head(net, &reg[i]);
if (!pp)
continue;
p = nf_entry_dereference(*pp);
if (WARN_ON_ONCE(!p))
continue;
__nf_unregister_net_hook(p, &reg[i]);
}
mutex_unlock(&nf_hook_mutex);
do {
n = min_t(unsigned int, hookcount, ARRAY_SIZE(to_free));
mutex_lock(&nf_hook_mutex);
for (i = 0, j = 0; i < hookcount && j < n; i++) {
pp = nf_hook_entry_head(net, &reg[i]);
if (!pp)
continue;
p = nf_entry_dereference(*pp);
if (!p)
continue;
to_free[j] = __nf_hook_entries_try_shrink(pp);
if (to_free[j])
++j;
}
mutex_unlock(&nf_hook_mutex);
if (j) {
unsigned int nfq;
synchronize_net();
/* need 2nd synchronize_net() if nfqueue is used, skb
* can get reinjected right before nf_queue_hook_drop()
*/
nfq = nf_queue_nf_hook_drop(net);
if (nfq)
synchronize_net();
for (i = 0; i < j; i++)
kvfree(to_free[i]);
}
reg += n;
hookcount -= n;
} while (hookcount > 0);
}
EXPORT_SYMBOL(nf_unregister_net_hooks);
/* Returns 1 if okfn() needs to be executed by the caller,
* -EPERM for NF_DROP, 0 otherwise. Caller must hold rcu_read_lock. */
int nf_hook_slow(struct sk_buff *skb, struct nf_hook_state *state,
const struct nf_hook_entries *e, unsigned int s)
{
unsigned int verdict;
int ret;
for (; s < e->num_hook_entries; s++) {
verdict = nf_hook_entry_hookfn(&e->hooks[s], skb, state);
switch (verdict & NF_VERDICT_MASK) {
case NF_ACCEPT:
break;
case NF_DROP:
kfree_skb(skb);
ret = NF_DROP_GETERR(verdict);
if (ret == 0)
ret = -EPERM;
return ret;
case NF_QUEUE:
ret = nf_queue(skb, state, e, s, verdict);
if (ret == 1)
continue;
return ret;
default:
/* Implicit handling for NF_STOLEN, as well as any other
* non conventional verdicts.
*/
return 0;
}
}
return 1;
}
EXPORT_SYMBOL(nf_hook_slow);
int skb_make_writable(struct sk_buff *skb, unsigned int writable_len)
{
if (writable_len > skb->len)
return 0;
/* Not exclusive use of packet? Must copy. */
if (!skb_cloned(skb)) {
if (writable_len <= skb_headlen(skb))
return 1;
} else if (skb_clone_writable(skb, writable_len))
return 1;
if (writable_len <= skb_headlen(skb))
writable_len = 0;
else
writable_len -= skb_headlen(skb);
return !!__pskb_pull_tail(skb, writable_len);
}
EXPORT_SYMBOL(skb_make_writable);
/* This needs to be compiled in any case to avoid dependencies between the
* nfnetlink_queue code and nf_conntrack.
*/
struct nfnl_ct_hook __rcu *nfnl_ct_hook __read_mostly;
EXPORT_SYMBOL_GPL(nfnl_ct_hook);
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
/* This does not belong here, but locally generated errors need it if connection
tracking in use: without this, connection may not be in hash table, and hence
manufactured ICMP or RST packets will not be associated with it. */
void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
__rcu __read_mostly;
EXPORT_SYMBOL(ip_ct_attach);
void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
{
void (*attach)(struct sk_buff *, const struct sk_buff *);
if (skb->_nfct) {
rcu_read_lock();
attach = rcu_dereference(ip_ct_attach);
if (attach)
attach(new, skb);
rcu_read_unlock();
}
}
EXPORT_SYMBOL(nf_ct_attach);
void (*nf_ct_destroy)(struct nf_conntrack *) __rcu __read_mostly;
EXPORT_SYMBOL(nf_ct_destroy);
void nf_conntrack_destroy(struct nf_conntrack *nfct)
{
void (*destroy)(struct nf_conntrack *);
rcu_read_lock();
destroy = rcu_dereference(nf_ct_destroy);
BUG_ON(destroy == NULL);
destroy(nfct);
rcu_read_unlock();
}
EXPORT_SYMBOL(nf_conntrack_destroy);
/* Built-in default zone used e.g. by modules. */
const struct nf_conntrack_zone nf_ct_zone_dflt = {
.id = NF_CT_DEFAULT_ZONE_ID,
.dir = NF_CT_DEFAULT_ZONE_DIR,
};
EXPORT_SYMBOL_GPL(nf_ct_zone_dflt);
#endif /* CONFIG_NF_CONNTRACK */
#ifdef CONFIG_NF_NAT_NEEDED
void (*nf_nat_decode_session_hook)(struct sk_buff *, struct flowi *);
EXPORT_SYMBOL(nf_nat_decode_session_hook);
#endif
static int __net_init netfilter_net_init(struct net *net)
{
int i, h;
for (i = 0; i < ARRAY_SIZE(net->nf.hooks); i++) {
for (h = 0; h < NF_MAX_HOOKS; h++)
RCU_INIT_POINTER(net->nf.hooks[i][h], NULL);
}
#ifdef CONFIG_PROC_FS
net->nf.proc_netfilter = proc_net_mkdir(net, "netfilter",
net->proc_net);
if (!net->nf.proc_netfilter) {
if (!net_eq(net, &init_net))
pr_err("cannot create netfilter proc entry");
return -ENOMEM;
}
#endif
return 0;
}
static void __net_exit netfilter_net_exit(struct net *net)
{
remove_proc_entry("netfilter", net->proc_net);
}
static struct pernet_operations netfilter_net_ops = {
.init = netfilter_net_init,
.exit = netfilter_net_exit,
};
int __init netfilter_init(void)
{
int ret;
ret = register_pernet_subsys(&netfilter_net_ops);
if (ret < 0)
goto err;
ret = netfilter_log_init();
if (ret < 0)
goto err_pernet;
return 0;
err_pernet:
unregister_pernet_subsys(&netfilter_net_ops);
err:
return ret;
}