From: Dmitry Vyukov <firstname.lastname@example.org>
To: Jakub Kicinski <email@example.com>
Cc: Aleksandr Nogikh <firstname.lastname@example.org>,
David Miller <email@example.com>,
Johannes Berg <firstname.lastname@example.org>,
Eric Dumazet <email@example.com>,
Andrey Konovalov <firstname.lastname@example.org>,
Marco Elver <email@example.com>,
Aleksandr Nogikh <firstname.lastname@example.org>
Subject: Re: [PATCH 1/2] net: store KCOV remote handle in sk_buff
Date: Mon, 12 Oct 2020 08:04:33 +0200 [thread overview]
Message-ID: <CACT4Y+aEQoRMO6eA7iQZf4dhOu2cD1ZbbH6TT4Rs_uQwG0PWYg@mail.gmail.com> (raw)
On Sat, Oct 10, 2020 at 5:14 PM Jakub Kicinski <email@example.com> wrote:
> On Sat, 10 Oct 2020 09:54:57 +0200 Dmitry Vyukov wrote:
> > On Sat, Oct 10, 2020 at 1:16 AM Jakub Kicinski <firstname.lastname@example.org> wrote:
> > > On Wed, 7 Oct 2020 10:17:25 +0000 Aleksandr Nogikh wrote:
> > > > From: Aleksandr Nogikh <email@example.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 <firstname.lastname@example.org>
> > >
> > > Could you use skb_extensions for this?
> > Why? If for space, this is already under a non-production ifdef.
> I understand, but the skb_ext infra is there for uncommon use cases
> like this one. Any particular reason you don't want to use it?
> The slight LoC increase?
> Is there any precedent for adding the kcov field to other performance
> critical structures?
I see. Yes, increase in complexity for no gain.
No, KCOV context wasn't added to anything as critical as sk_buff.
It seems there is no established practice both ways -- I don't see
anything debug-related in sk_buff nor in skb_ext_id...
next prev parent reply other threads:[~2020-10-12 6:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 10:17 [PATCH 0/2] net, mac80211: enable KCOV remote coverage collection for 802.11 frame handling Aleksandr Nogikh
2020-10-07 10:17 ` [PATCH 1/2] net: store KCOV remote handle in sk_buff Aleksandr Nogikh
2020-10-09 23:15 ` Jakub Kicinski
2020-10-10 7:54 ` Dmitry Vyukov
2020-10-10 15:14 ` Jakub Kicinski
2020-10-12 6:04 ` Dmitry Vyukov [this message]
2020-10-13 15:59 ` Aleksandr Nogikh
2020-10-13 16:50 ` Jakub Kicinski
2020-10-15 19:04 ` Willem de Bruijn
2020-10-16 14:20 ` Aleksandr Nogikh
2020-10-12 7:12 ` Johannes Berg
2020-10-12 10:10 ` Aleksandr Nogikh
2020-10-07 10:17 ` [PATCH 2/2] mac80211: add KCOV remote annotations to incoming frame processing Aleksandr Nogikh
2020-10-07 11:48 ` [PATCH 0/2] net, mac80211: enable KCOV remote coverage collection for 802.11 frame handling Johannes Berg
2020-10-07 14:40 ` Aleksandr Nogikh
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