netdev - Re: [PATCH net-next 12/14] net: sched: act_mirred: remove dependency on rtnl lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 08 Aug 2018 14:21:39 +0300
From:   Vlad Buslov <vladbu@...lanox.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
        xiyou.wangcong@...il.com, pablo@...filter.org,
        kadlec@...ckhole.kfki.hu, fw@...len.de, ast@...nel.org,
        daniel@...earbox.net, edumazet@...gle.com, keescook@...omium.org,
        marcelo.leitner@...il.com
Subject: Re: [PATCH net-next 12/14] net: sched: act_mirred: remove dependency on rtnl lock


On Wed 08 Aug 2018 at 08:54, Jiri Pirko <jiri@...nulli.us> wrote:
> Wed, Aug 08, 2018 at 10:47:04AM CEST, vladbu@...lanox.com wrote:
>>
>>On Wed 08 Aug 2018 at 08:03, Jiri Pirko <jiri@...nulli.us> wrote:
>>> Wed, Aug 08, 2018 at 09:40:35AM CEST, vladbu@...lanox.com wrote:
>>>>
>>>>On Tue 07 Aug 2018 at 16:36, Jiri Pirko <jiri@...nulli.us> wrote:
>>>>> Mon, Aug 06, 2018 at 08:54:23AM CEST, vladbu@...lanox.com wrote:
>>>>>
>>>>> [...]
>>>>>
>>>>>>diff --git a/include/net/tc_act/tc_tunnel_key.h b/include/net/tc_act/tc_tunnel_key.h
>>>>>>index 46b8c7f1c8d5..e6e475d788c6 100644
>>>>>>--- a/include/net/tc_act/tc_tunnel_key.h
>>>>>>+++ b/include/net/tc_act/tc_tunnel_key.h
>>>>>>@@ -30,26 +30,47 @@ struct tcf_tunnel_key {
>>>>>> 
>>>>>> static inline bool is_tcf_tunnel_set(const struct tc_action *a)
>>>>>> {
>>>>>>+	bool ret = false;
>>>>>> #ifdef CONFIG_NET_CLS_ACT
>>>>>> 	struct tcf_tunnel_key *t = to_tunnel_key(a);
>>>>>>-	struct tcf_tunnel_key_params *params = rtnl_dereference(t->params);
>>>>>>+	struct tcf_tunnel_key_params *params;
>>>>>> 
>>>>>>+	rcu_read_lock();
>>>>>>+	params = rcu_dereference(t->params);
>>>>>> 	if (a->ops && a->ops->type == TCA_ACT_TUNNEL_KEY)
>>>>>>-		return params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
>>>>>>+		ret = params->tcft_action == TCA_TUNNEL_KEY_ACT_SET;
>>>>>>+	rcu_read_unlock();
>>>>>> #endif
>>>>>>-	return false;
>>>>>>+	return ret;
>>>>>> }
>>>>>> 
>>>>>> static inline bool is_tcf_tunnel_release(const struct tc_action *a)
>>>>>
>>>>> Why are these tunnel things in a mirred patch?
>>>>
>>>>Mistake during re-slit. Will move those to tunnel_key patch.
>>>
>>> Are you sure that the changes are safe? I just quickly looked over it
>>> and it smells:
>>> drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:
>>>                 if (is_tcf_tunnel_set(a)) {
>>>                         info = tcf_tunnel_info(a);
>>>
>>> Why the "t->params" can't be nulled in the middle?
>>
>>First of all, no API is actually "unlocked" with this patch. It is a
>>preparation, rtnl mutex is still in use.
>>
>>Callers of these functions will have to be updated, for example, to use
>>their _rcu version while holding rcu_read_lock.
>
> I don't see any rcu version of these. I think that it would be good to
> convert the callers to rcu and you can avoid these changes.

Understood. Will move helper function changes to standalone patch.