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Date:   Wed, 11 Mar 2020 13:06:33 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Sven Schnelle <svens@linux.ibm.com>
Cc:     Andy Lutomirski <luto@amacapital.net>,
        Will Drewry <wad@chromium.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH] seccomp: add compat_ioctl for seccomp notify
Message-ID: <202003111305.87B2A84A@keescook>
References: <20200310123332.42255-1-svens@linux.ibm.com>
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On Tue, Mar 10, 2020 at 01:33:32PM +0100, Sven Schnelle wrote:
> Hi,
> 
> executing the seccomp_bpf testsuite with 32 bit userland (both s390 and x86)
> doesn't work because there's no compat_ioctl handler defined. Is that something
> that is supposed to work? Disclaimer: I don't know enough about seccomp to judge
> whether there would be some adjustments required in the compat ioctl handler.
> Just setting it to seccomp_notify_ioctl() makes the testsuite pass, but i'm not
> sure whether that's correct.
> 
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>

Whoops! Yes, running a mixed environment (64-bit kernel and 32-bit
userspace) shows this as broken. I'll tweak the commit log a bit and
apply it. Thanks!

-Kees

> ---
>  kernel/seccomp.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> index b6ea3dcb57bf..683c81e4861e 100644
> --- a/kernel/seccomp.c
> +++ b/kernel/seccomp.c
> @@ -1221,6 +1221,7 @@ static const struct file_operations seccomp_notify_ops = {
>  	.poll = seccomp_notify_poll,
>  	.release = seccomp_notify_release,
>  	.unlocked_ioctl = seccomp_notify_ioctl,
> +	.compat_ioctl = seccomp_notify_ioctl,
>  };
>  
>  static struct file *init_listener(struct seccomp_filter *filter)
> -- 
> 2.17.1
> 

-- 
Kees Cook