From: Ziyang Xuan <william.xuanziyang@huawei.com>
To: <pablo@netfilter.org>, <kadlec@netfilter.org>, <fw@strlen.de>,
<netfilter-devel@vger.kernel.org>
Subject: [PATCH nft v2] netfilter: nf_tables: Fix pertential data-race in __nft_flowtable_type_get()
Date: Wed, 3 Apr 2024 15:22:04 +0800 [thread overview]
Message-ID: <20240403072204.2139712-1-william.xuanziyang@huawei.com> (raw)
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: 3b49e2e94e6e ("netfilter: nf_tables: add flow table netlink frontend")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
v2:
- Move rcu_read_lock() outside to caller. [Florian Westphal]
- Add "Fixes" tag.
---
net/netfilter/nf_tables_api.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index fd86f2720c9e..47e1a22e8fb1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8293,11 +8293,12 @@ 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;
}
@@ -8309,9 +8310,13 @@ 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
--
2.25.1
next reply other threads:[~2024-04-03 7:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-03 7:22 Ziyang Xuan [this message]
2024-04-03 8:01 ` [PATCH nft v2] netfilter: nf_tables: Fix pertential data-race in __nft_flowtable_type_get() Florian Westphal
2024-04-03 8:30 ` Ziyang Xuan (William)
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