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netfilter: core: export raw versions of add/delete hook functions

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This will allow the nat core to reuse the nf_hook infrastructure
to maintain nat lookup functions.

The raw versions don't assume a particular hook location, the
functions get added/deleted from the hook blob that is passed to the
functions.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2018-05-14 23:46:56 +02:00 committed by Pablo Neira Ayuso
parent 4e25ceb80b
commit 06cad3acf0
2 changed files with 59 additions and 21 deletions
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75
net/netfilter/core.c
View File

@ -186,9 +186,31 @@ static void hooks_validate(const struct nf_hook_entries *hooks)
#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
@ -201,14 +223,14 @@ static void hooks_validate(const struct nf_hook_entries *hooks)
*
* Returns address to free, or NULL.
*/
static void *__nf_hook_entries_try_shrink(struct nf_hook_entries __rcu **pp)
static void *__nf_hook_entries_try_shrink(struct nf_hook_entries *old,
struct nf_hook_entries __rcu **pp)
{
struct nf_hook_entries *old, *new = NULL;
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;
old = nf_entry_dereference(*pp);
if (WARN_ON_ONCE(!old))
return NULL;
@ -347,11 +369,10 @@ static int __nf_register_net_hook(struct net *net, int pf,
* This cannot fail, hook unregistration must always succeed.
* Therefore replace the to-be-removed hook with a dummy hook.
*/
static void nf_remove_net_hook(struct nf_hook_entries *old,
const struct nf_hook_ops *unreg, int pf)
static bool nf_remove_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);
@ -360,21 +381,10 @@ static void nf_remove_net_hook(struct nf_hook_entries *old,
continue;
WRITE_ONCE(old->hooks[i].hook, accept_all);
WRITE_ONCE(orig_ops[i], &dummy_ops);
found = true;
break;
return true;
}
if (found) {
#ifdef CONFIG_NETFILTER_INGRESS
if (pf == NFPROTO_NETDEV && unreg->hooknum == NF_NETDEV_INGRESS)
net_dec_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_dec(&nf_hooks_needed[pf][unreg->hooknum]);
#endif
} else {
WARN_ONCE(1, "hook not found, pf %d num %d", pf, unreg->hooknum);
}
return false;
}
static void __nf_unregister_net_hook(struct net *net, int pf,
@ -395,9 +405,19 @@ static void __nf_unregister_net_hook(struct net *net, int pf,
return;
}
nf_remove_net_hook(p, reg, pf);
if (nf_remove_net_hook(p, reg)) {
#ifdef CONFIG_NETFILTER_INGRESS
if (pf == NFPROTO_NETDEV && reg->hooknum == NF_NETDEV_INGRESS)
net_dec_ingress_queue();
#endif
#ifdef HAVE_JUMP_LABEL
static_key_slow_dec(&nf_hooks_needed[pf][reg->hooknum]);
#endif
} else {
WARN_ONCE(1, "hook not found, pf %d num %d", pf, reg->hooknum);
}
p = __nf_hook_entries_try_shrink(pp);
p = __nf_hook_entries_try_shrink(p, pp);
mutex_unlock(&nf_hook_mutex);
if (!p)
return;
@ -417,6 +437,19 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *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;

5
net/netfilter/nf_internals.h
View File

@ -15,4 +15,9 @@ void nf_queue_nf_hook_drop(struct net *net);
/* nf_log.c */
int __init netfilter_log_init(void);
/* core.c */
void nf_hook_entries_delete_raw(struct nf_hook_entries __rcu **pp,
const struct nf_hook_ops *reg);
int nf_hook_entries_insert_raw(struct nf_hook_entries __rcu **pp,
const struct nf_hook_ops *reg);
#endif