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netfilter: nf_tables: Fix potential data-race in __nft_flowtable_type_get() 

nft_unregister_flowtable_type() within nf_flow_inet_module_exit() can
concurrent with __nft_flowtable_type_get() within nf_tables_newflowtable().
And thhere is not any protection when iterate over nf_tables_flowtables
list in __nft_flowtable_type_get(). Therefore, there is pertential
data-race of nf_tables_flowtables list entry.

Use list_for_each_entry_rcu() to iterate over nf_tables_flowtables list
in __nft_flowtable_type_get(), and use rcu_read_lock() in the caller
nft_flowtable_type_get() to protect the entire type query process.

Fixes: 3b49e2e94e ("netfilter: nf_tables: add flow table netlink frontend")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Ziyang Xuan 2024-04-03 15:22:04 +08:00 committed by Pablo Neira Ayuso
parent 994209ddf4
commit 24225011d8
1 changed files with 7 additions and 2 deletions
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9
net/netfilter/nf_tables_api.c
View File

@ -8296,11 +8296,12 @@ static int nft_flowtable_parse_hook(const struct nft_ctx *ctx,
return err;
}
/* call under rcu_read_lock */
static const struct nf_flowtable_type *__nft_flowtable_type_get(u8 family)
{
const struct nf_flowtable_type *type;
list_for_each_entry(type, &nf_tables_flowtables, list) {
list_for_each_entry_rcu(type, &nf_tables_flowtables, list) {
if (family == type->family)
return type;
}
@ -8312,9 +8313,13 @@ nft_flowtable_type_get(struct net *net, u8 family)
{
const struct nf_flowtable_type *type;
rcu_read_lock();
type = __nft_flowtable_type_get(family);
if (type != NULL && try_module_get(type->owner))
if (type != NULL && try_module_get(type->owner)) {
rcu_read_unlock();
return type;
}
rcu_read_unlock();
lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES