netdev - Re: [PATCH net v2 00/18] net/sched: validate the control action with all the other parameters

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Message-Id: <20190320.123631.393081695945678985.davem@davemloft.net>
Date:   Wed, 20 Mar 2019 12:36:31 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     dcaratti@...hat.com
Cc:     xiyou.wangcong@...il.com, vladbu@...lanox.com, jhs@...atatu.com,
        jiri@...nulli.us, netdev@...r.kernel.org, pabeni@...hat.com
Subject: Re: [PATCH net v2 00/18] net/sched: validate the control action
 with all the other parameters

From: Davide Caratti <dcaratti@...hat.com>
Date: Wed, 20 Mar 2019 14:59:58 +0100

> currently, the kernel checks for bad values of the control action in
> tcf_action_init_1(), after a successful call to the action's init()
> function. When the control action is 'goto chain', this causes two
> undesired behaviors:
 ...
> The above problems can be fixed if we validate the control action in each
> action's init() function, the same way as we are already doing for all the
> other configuration parameters.
> Now that chains can be released after an action is replaced, we need to
> care about concurrent access of 'goto_chain' pointer: ensure we access it
> through RCU, like we did with most action-specific configuration parameters.
> 
> - Patch 1 removes the wrong checks and provides functions that can be
>   used to properly validate control actions in  individual actions 
> - Patch 2 to 16 fix individual actions, and add TDC selftest code to
>   verify the correct behavior (2)
> - Patch 17 and 18 fix concurrent access issues on 'goto_chain', that can be
>   observed after the chain refcount leak is fixed.
 ...

This needs some careful review, obviously.

But meanwhile I will say that I love how this patch series is split up, with
each action conversion being accompanied by a test case.