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Date: Wed, 24 Jan 2024 11:51:49 -0800
From: Kees Cook <keescook@chromium.org>
To: Kevin Locke <kevin@kevinlocke.name>,
	Josh Triplett <josh@joshtriplett.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	John Johansen <john.johansen@canonical.com>,
	Paul Moore <paul@paul-moore.com>, James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Kentaro Takeda <takedakn@nttdata.co.jp>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	Eric Biederman <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] exec: Check __FMODE_EXEC instead of in_execve for LSMs
Message-ID: <202401241151.25D468FE@keescook>
References: <20240124192228.work.788-kees@kernel.org>
 <ZbFneq3URF5lLAT7@kevinlocke.name>
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In-Reply-To: <ZbFneq3URF5lLAT7@kevinlocke.name>

On Wed, Jan 24, 2024 at 12:39:38PM -0700, Kevin Locke wrote:
> On Wed, 2024-01-24 at 11:22 -0800, Kees Cook wrote:
> > After commit 978ffcbf00d8 ("execve: open the executable file before
> > doing anything else"), current->in_execve was no longer in sync with the
> > open(). This broke AppArmor and TOMOYO which depend on this flag to
> > distinguish "open" operations from being "exec" operations.
> > 
> > Instead of moving around in_execve, switch to using __FMODE_EXEC, which
> > is where the "is this an exec?" intent is stored. Note that TOMOYO still
> > uses in_execve around cred handling.
> 
> It solves the AppArmor issue I was experiencing and I don't notice any
> other issues.
> 
> Tested-by: Kevin Locke <kevin@kevinlocke.name>

Thanks!

Sounds like Linus has taken the patch directly, and I'll send a follow-up
PR with other clean-ups.

-Kees

-- 
Kees Cook