netdev - Re: [PATCH 1/2] net: store KCOV remote handle in sk

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Message-ID: <20201009161558.57792e1a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 9 Oct 2020 16:15:58 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Aleksandr Nogikh <a.nogikh@...il.com>
Cc:     davem@...emloft.net, johannes@...solutions.net,
        edumazet@...gle.com, andreyknvl@...gle.com, dvyukov@...gle.com,
        elver@...gle.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        nogikh@...gle.com
Subject: Re: [PATCH 1/2] net: store KCOV remote handle in sk_buff

On Wed,  7 Oct 2020 10:17:25 +0000 Aleksandr Nogikh wrote:
> From: Aleksandr Nogikh <nogikh@...gle.com>
> 
> Remote KCOV coverage collection enables coverage-guided fuzzing of the
> code that is not reachable during normal system call execution. It is
> especially helpful for fuzzing networking subsystems, where it is
> common to perform packet handling in separate work queues even for the
> packets that originated directly from the user space.
> 
> Enable coverage-guided frame injection by adding a kcov_handle
> parameter to sk_buff structure. Initialization in __alloc_skb ensures
> that no socket buffer that was generated during a system call will be
> missed.
> 
> Code that is of interest and that performs packet processing should be
> annotated with kcov_remote_start()/kcov_remote_stop().
> 
> An alternative approach is to determine kcov_handle solely on the
> basis of the device/interface that received the specific socket
> buffer. However, in this case it would be impossible to distinguish
> between packets that originated from normal background network
> processes and those that were intentionally injected from the user
> space.
> 
> Signed-off-by: Aleksandr Nogikh <nogikh@...gle.com>

Could you use skb_extensions for this?