linux-kernel - Re: [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection

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Message-ID: <20200716210601.GN12769@casper.infradead.org>
Date:   Thu, 16 Jul 2020 22:06:01 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org,
        kernel@...labora.com, luto@...nel.org, gofmanp@...il.com,
        keescook@...omium.org, linux-kselftest@...r.kernel.org,
        shuah@...nel.org
Subject: Re: [PATCH v4 1/2] kernel: Implement selective syscall userspace
 redirection

On Thu, Jul 16, 2020 at 03:31:40PM -0400, Gabriel Krisman Bertazi wrote:
> selector is an optional pointer to a char-sized userspace memory region
> that has a key switch for the mechanism. This key switch is set to
> either PR_SYS_DISPATCH_ON, PR_SYS_DISPATCH_OFF to enable and disable the
> redirection without calling the kernel.
> 
> The feature is meant to be set per-thread and it is disabled on
> fork/clone/execv.

Disabled on exec.  Disabled in the child on clone/fork (and vfork, I
think).

That means we don't need to worry about it interacting badly with
a setuid program, right?