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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:
parent
994209ddf4
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@ -8296,11 +8296,12 @@ static int nft_flowtable_parse_hook(const struct nft_ctx *ctx,
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return err;
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}
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/* call under rcu_read_lock */
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static const struct nf_flowtable_type *__nft_flowtable_type_get(u8 family)
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{
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const struct nf_flowtable_type *type;
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list_for_each_entry(type, &nf_tables_flowtables, list) {
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list_for_each_entry_rcu(type, &nf_tables_flowtables, list) {
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if (family == type->family)
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return type;
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}
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@ -8312,9 +8313,13 @@ nft_flowtable_type_get(struct net *net, u8 family)
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{
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const struct nf_flowtable_type *type;
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rcu_read_lock();
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type = __nft_flowtable_type_get(family);
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if (type != NULL && try_module_get(type->owner))
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if (type != NULL && try_module_get(type->owner)) {
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rcu_read_unlock();
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return type;
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}
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rcu_read_unlock();
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lockdep_nfnl_nft_mutex_not_held();
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#ifdef CONFIG_MODULES
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