blob: 3a32a813fcde6c8d7c834a0a0f5c7df0de90c834 [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.
*
* This code is GPL.
*/
#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/netfilter/nf_queue.h>
#include <net/sock.h>
#include "nf_internals.h"
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);
#ifdef CONFIG_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 +
sizeof(struct nf_hook_entries_rcu_head);
if (num == 0)
return NULL;
e = kvzalloc(alloc, GFP_KERNEL);
if (e)
e->num_hook_entries = num;
return e;
}
static void __nf_hook_entries_free(struct rcu_head *h)
{
struct nf_hook_entries_rcu_head *head;
head = container_of(h, struct nf_hook_entries_rcu_head, head);
kvfree(head->allocation);
}
static void nf_hook_entries_free(struct nf_hook_entries *e)
{
struct nf_hook_entries_rcu_head *head;
struct nf_hook_ops **ops;
unsigned int num;
if (!e)
return;
num = e->num_hook_entries;
ops = nf_hook_entries_get_hook_ops(e);
head = (void *)&ops[num];
head->allocation = e;
call_rcu(&head->head, __nf_hook_entries_free);
}
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_MISC
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
}
int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
const struct nf_hook_ops *reg)
{
struct nf_hook_entries *new_hooks;
struct nf_hook_entries *p;
p = rcu_dereference_raw(*pp);
new_hooks = nf_hook_entries_grow(p, reg);
if (IS_ERR(new_hooks))
return PTR_ERR(new_hooks);
hooks_validate(new_hooks);
rcu_assign_pointer(*pp, new_hooks);
BUG_ON(p == new_hooks);
nf_hook_entries_free(p);
return 0;
}
EXPORT_SYMBOL_GPL(nf_hook_entries_insert_raw);
/*
* __nf_hook_entries_try_shrink - try to shrink hook array
*
* @old -- current hook blob at @pp
* @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 *old,
struct nf_hook_entries __rcu **pp)
{
unsigned int i, j, skip = 0, hook_entries;
struct nf_hook_entries *new = NULL;
struct nf_hook_ops **orig_ops;
struct nf_hook_ops **new_ops;
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, int pf, unsigned int hooknum,
struct net_device *dev)
{
switch (pf) {
case NFPROTO_NETDEV:
break;
#ifdef CONFIG_NETFILTER_FAMILY_ARP
case NFPROTO_ARP:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_arp) <= hooknum))
return NULL;
return net->nf.hooks_arp + hooknum;
#endif
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
case NFPROTO_BRIDGE:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_bridge) <= hooknum))
return NULL;
return net->nf.hooks_bridge + hooknum;
#endif
#ifdef CONFIG_NETFILTER_INGRESS
case NFPROTO_INET:
if (WARN_ON_ONCE(hooknum != NF_INET_INGRESS))
return NULL;
if (!dev || dev_net(dev) != net) {
WARN_ON_ONCE(1);
return NULL;
}
return &dev->nf_hooks_ingress;
#endif
case NFPROTO_IPV4:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv4) <= hooknum))
return NULL;
return net->nf.hooks_ipv4 + hooknum;
case NFPROTO_IPV6:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_ipv6) <= hooknum))
return NULL;
return net->nf.hooks_ipv6 + hooknum;
#if IS_ENABLED(CONFIG_DECNET)
case NFPROTO_DECNET:
if (WARN_ON_ONCE(ARRAY_SIZE(net->nf.hooks_decnet) <= hooknum))
return NULL;
return net->nf.hooks_decnet + hooknum;
#endif
default:
WARN_ON_ONCE(1);
return NULL;
}
#ifdef CONFIG_NETFILTER_INGRESS
if (hooknum == NF_NETDEV_INGRESS) {
if (dev && dev_net(dev) == net)
return &dev->nf_hooks_ingress;
}
#endif
#ifdef CONFIG_NETFILTER_EGRESS
if (hooknum == NF_NETDEV_EGRESS) {
if (dev && dev_net(dev) == net)
return &dev->nf_hooks_egress;
}
#endif
WARN_ON_ONCE(1);
return NULL;
}
static int nf_ingress_check(struct net *net, const struct nf_hook_ops *reg,
int hooknum)
{
#ifndef CONFIG_NETFILTER_INGRESS
if (reg->hooknum == hooknum)
return -EOPNOTSUPP;
#endif
if (reg->hooknum != hooknum ||
!reg->dev || dev_net(reg->dev) != net)
return -EINVAL;
return 0;
}
static inline bool nf_ingress_hook(const struct nf_hook_ops *reg, int pf)
{
if ((pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS) ||
(pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS))
return true;
return false;
}
static inline bool nf_egress_hook(const struct nf_hook_ops *reg, int pf)
{
return pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_EGRESS;
}
static void nf_static_key_inc(const struct nf_hook_ops *reg, int pf)
{
#ifdef CONFIG_JUMP_LABEL
int hooknum;
if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
pf = NFPROTO_NETDEV;
hooknum = NF_NETDEV_INGRESS;
} else {
hooknum = reg->hooknum;
}
static_key_slow_inc(&nf_hooks_needed[pf][hooknum]);
#endif
}
static void nf_static_key_dec(const struct nf_hook_ops *reg, int pf)
{
#ifdef CONFIG_JUMP_LABEL
int hooknum;
if (pf == NFPROTO_INET && reg->hooknum == NF_INET_INGRESS) {
pf = NFPROTO_NETDEV;
hooknum = NF_NETDEV_INGRESS;
} else {
hooknum = reg->hooknum;
}
static_key_slow_dec(&nf_hooks_needed[pf][hooknum]);
#endif
}
static int __nf_register_net_hook(struct net *net, int pf,
const struct nf_hook_ops *reg)
{
struct nf_hook_entries *p, *new_hooks;
struct nf_hook_entries __rcu **pp;
int err;
switch (pf) {
case NFPROTO_NETDEV:
#ifndef CONFIG_NETFILTER_INGRESS
if (reg->hooknum == NF_NETDEV_INGRESS)
return -EOPNOTSUPP;
#endif
#ifndef CONFIG_NETFILTER_EGRESS
if (reg->hooknum == NF_NETDEV_EGRESS)
return -EOPNOTSUPP;
#endif
if ((reg->hooknum != NF_NETDEV_INGRESS &&
reg->hooknum != NF_NETDEV_EGRESS) ||
!reg->dev || dev_net(reg->dev) != net)
return -EINVAL;
break;
case NFPROTO_INET:
if (reg->hooknum != NF_INET_INGRESS)
break;
err = nf_ingress_check(net, reg, NF_INET_INGRESS);
if (err < 0)
return err;
break;
}
pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
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 (nf_ingress_hook(reg, pf))
net_inc_ingress_queue();
#endif
#ifdef CONFIG_NETFILTER_EGRESS
if (nf_egress_hook(reg, pf))
net_inc_egress_queue();
#endif
nf_static_key_inc(reg, pf);
BUG_ON(p == new_hooks);
nf_hook_entries_free(p);
return 0;
}
/*
* nf_remove_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 bool nf_remove_net_hook(struct nf_hook_entries *old,
const struct nf_hook_ops *unreg)
{
struct nf_hook_ops **orig_ops;
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], (void *)&dummy_ops);
return true;
}
return false;
}
static void __nf_unregister_net_hook(struct net *net, int pf,
const struct nf_hook_ops *reg)
{
struct nf_hook_entries __rcu **pp;
struct nf_hook_entries *p;
pp = nf_hook_entry_head(net, pf, reg->hooknum, reg->dev);
if (!pp)
return;
mutex_lock(&nf_hook_mutex);
p = nf_entry_dereference(*pp);
if (WARN_ON_ONCE(!p)) {
mutex_unlock(&nf_hook_mutex);
return;
}
if (nf_remove_net_hook(p, reg)) {
#ifdef CONFIG_NETFILTER_INGRESS
if (nf_ingress_hook(reg, pf))
net_dec_ingress_queue();
#endif
#ifdef CONFIG_NETFILTER_EGRESS
if (nf_egress_hook(reg, pf))
net_dec_egress_queue();
#endif
nf_static_key_dec(reg, pf);
} else {
WARN_ONCE(1, "hook not found, pf %d num %d", pf, reg->hooknum);
}
p = __nf_hook_entries_try_shrink(p, pp);
mutex_unlock(&nf_hook_mutex);
if (!p)
return;
nf_queue_nf_hook_drop(net);
nf_hook_entries_free(p);
}
void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
if (reg->pf == NFPROTO_INET) {
if (reg->hooknum == NF_INET_INGRESS) {
__nf_unregister_net_hook(net, NFPROTO_INET, reg);
} else {
__nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
__nf_unregister_net_hook(net, NFPROTO_IPV6, reg);
}
} else {
__nf_unregister_net_hook(net, reg->pf, reg);
}
}
EXPORT_SYMBOL(nf_unregister_net_hook);
void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
const struct nf_hook_ops *reg)
{
struct nf_hook_entries *p;
p = rcu_dereference_raw(*pp);
if (nf_remove_net_hook(p, reg)) {
p = __nf_hook_entries_try_shrink(p, pp);
nf_hook_entries_free(p);
}
}
EXPORT_SYMBOL_GPL(nf_hook_entries_delete_raw);
int nf_register_net_hook(struct net *net, const struct nf_hook_ops *reg)
{
int err;
if (reg->pf == NFPROTO_INET) {
if (reg->hooknum == NF_INET_INGRESS) {
err = __nf_register_net_hook(net, NFPROTO_INET, reg);
if (err < 0)
return err;
} else {
err = __nf_register_net_hook(net, NFPROTO_IPV4, reg);
if (err < 0)
return err;
err = __nf_register_net_hook(net, NFPROTO_IPV6, reg);
if (err < 0) {
__nf_unregister_net_hook(net, NFPROTO_IPV4, reg);
return err;
}
}
} else {
err = __nf_register_net_hook(net, reg->pf, reg);
if (err < 0)
return err;
}
return 0;
}
EXPORT_SYMBOL(nf_register_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)
{
unsigned int i;
for (i = 0; i < hookcount; i++)
nf_unregister_net_hook(net, &reg[i]);
}
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, 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);
void nf_hook_slow_list(struct list_head *head, struct nf_hook_state *state,
const struct nf_hook_entries *e)
{
struct sk_buff *skb, *next;
struct list_head sublist;
int ret;
INIT_LIST_HEAD(&sublist);
list_for_each_entry_safe(skb, next, head, list) {
skb_list_del_init(skb);
ret = nf_hook_slow(skb, state, e, 0);
if (ret == 1)
list_add_tail(&skb->list, &sublist);
}
/* Put passed packets back on main list */
list_splice(&sublist, head);
}
EXPORT_SYMBOL(nf_hook_slow_list);
/* 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);
struct nf_ct_hook __rcu *nf_ct_hook __read_mostly;
EXPORT_SYMBOL_GPL(nf_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);
struct nf_nat_hook __rcu *nf_nat_hook __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_hook);
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_conntrack_destroy(struct nf_conntrack *nfct)
{
struct nf_ct_hook *ct_hook;
rcu_read_lock();
ct_hook = rcu_dereference(nf_ct_hook);
BUG_ON(ct_hook == NULL);
ct_hook->destroy(nfct);
rcu_read_unlock();
}
EXPORT_SYMBOL(nf_conntrack_destroy);
bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
const struct sk_buff *skb)
{
struct nf_ct_hook *ct_hook;
bool ret = false;
rcu_read_lock();
ct_hook = rcu_dereference(nf_ct_hook);
if (ct_hook)
ret = ct_hook->get_tuple_skb(dst_tuple, skb);
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL(nf_ct_get_tuple_skb);
/* 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 */
static void __net_init
__netfilter_net_init(struct nf_hook_entries __rcu **e, int max)
{
int h;
for (h = 0; h < max; h++)
RCU_INIT_POINTER(e[h], NULL);
}
static int __net_init netfilter_net_init(struct net *net)
{
__netfilter_net_init(net->nf.hooks_ipv4, ARRAY_SIZE(net->nf.hooks_ipv4));
__netfilter_net_init(net->nf.hooks_ipv6, ARRAY_SIZE(net->nf.hooks_ipv6));
#ifdef CONFIG_NETFILTER_FAMILY_ARP
__netfilter_net_init(net->nf.hooks_arp, ARRAY_SIZE(net->nf.hooks_arp));
#endif
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
__netfilter_net_init(net->nf.hooks_bridge, ARRAY_SIZE(net->nf.hooks_bridge));
#endif
#if IS_ENABLED(CONFIG_DECNET)
__netfilter_net_init(net->nf.hooks_decnet, ARRAY_SIZE(net->nf.hooks_decnet));
#endif
#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;
}