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From: [email protected] (Eric W. Biederman)
To: Jens Axboe <[email protected]>
Cc: [email protected], [email protected],
	[email protected], [email protected],
	Stefan Metzmacher <[email protected]>
Subject: Re: [PATCH 1/2] signal: don't allow sending any signals to PF_IO_WORKER threads
Date: Sat, 20 Mar 2021 11:18:29 -0500	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]> (Jens Axboe's message of "Sat, 20 Mar 2021 09:38:31 -0600")

Jens Axboe <[email protected]> writes:

> They don't take signals individually, and even if they share signals with
> the parent task, don't allow them to be delivered through the worker
> thread.

This is silly I know, but why do we care?

The creds should be reasonably in-sync with the rest of the threads.

There are other threads that will receive the signal, especially when
you worry about group_send_sig_info.  Which signal sending code paths
are actually a problem.

> Reported-by: Stefan Metzmacher <[email protected]>
> Signed-off-by: Jens Axboe <[email protected]>
> ---
>  kernel/signal.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index ba4d1ef39a9e..730ecd3d6faf 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -833,6 +833,9 @@ static int check_kill_permission(int sig, struct kernel_siginfo *info,
>  
>  	if (!valid_signal(sig))
>  		return -EINVAL;
> +	/* PF_IO_WORKER threads don't take any signals */
> +	if (t->flags & PF_IO_WORKER)
> +		return -EPERM;
>  
>  	if (!si_fromuser(info))
>  		return 0;

  reply	other threads:[~2021-03-20 16:20 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-20 15:38 [PATCHSET 0/2] PF_IO_WORKER signal tweaks Jens Axboe
2021-03-20 15:38 ` [PATCH 1/2] signal: don't allow sending any signals to PF_IO_WORKER threads Jens Axboe
2021-03-20 16:18   ` Eric W. Biederman [this message]
2021-03-20 17:56     ` Linus Torvalds
2021-03-20 21:38       ` Eric W. Biederman
2021-03-20 22:42         ` Jens Axboe
2021-03-21 14:54           ` Eric W. Biederman
2021-03-21 15:40             ` Jens Axboe
2021-03-20 15:38 ` [PATCH 2/2] signal: don't allow STOP on " Jens Axboe
2021-03-20 16:21   ` Eric W. Biederman
2021-03-22 16:18     ` Oleg Nesterov
2021-03-22 16:15   ` Oleg Nesterov
2021-03-20 16:26 ` [PATCHSET 0/2] PF_IO_WORKER signal tweaks Eric W. Biederman
2021-03-20 17:51   ` Linus Torvalds
2021-03-20 19:18     ` Linus Torvalds
2021-03-20 22:08       ` Eric W. Biederman
2021-03-20 22:53         ` Jens Axboe
2021-03-21 15:18           ` Eric W. Biederman
2021-03-21 15:42             ` Jens Axboe
2021-03-20 22:56       ` Jens Axboe
2021-03-20 17:05 ` kernel test robot
2021-03-20 17:05 ` kernel test robot
2021-03-20 19:10 ` kernel test robot
2021-03-22 16:05 ` Oleg Nesterov

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