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Date: Wed, 24 Jan 2024 12:39:38 -0700
From: Kevin Locke <kevin@kevinlocke.name>
To: Kees Cook <keescook@chromium.org>
Cc: 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: <ZbFneq3URF5lLAT7@kevinlocke.name>
Mail-Followup-To: Kevin Locke <kevin@kevinlocke.name>,
	Kees Cook <keescook@chromium.org>,
	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
References: <20240124192228.work.788-kees@kernel.org>
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In-Reply-To: <20240124192228.work.788-kees@kernel.org>

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!
Kevin