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	Fri, 29 Nov 2024 03:34:19 +0000
Date: Fri, 29 Nov 2024 03:34:19 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <kees@kernel.org>, linux-kernel@vger.kernel.org,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Nir Lichtman <nir@lichtman.org>,
	Tycho Andersen <tandersen@netflix.com>,
	Vegard Nossum <vegard.nossum@oracle.com>
Subject: Re: [GIT PULL] execve updates for v6.13-rc1 (take 2)
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Thu, Nov 28, 2024 at 06:43:31PM -0800, Linus Torvalds wrote:
> A sane setup has lots of options
> 
>  - just use execve() with the actual name of the executable
> 
>  - use hardlinks and use execveat()
> 
>  - use open() on a symlink and then execveat() of that file, and get
> the actual name of the executable behind the symlink
> 
>  - disagree about comm[] being relevant at all, and don't use it, and
> don't use tools that do
> 
> and none of those are wrong decisions.

Just one thing - IMO we want to use the relative pathname when it's
not empty.  Even in execveat().  Because some wanker *will* decide
that newer is better and make libc use execveat() to implement execve().
Which won't be spotted for about a year, and when it does we'll get
seriously stuck.

I agree that for fexecve() the only sane approach is to go by whatever
that opened file refers to; I'm not sold on the _usefulness_ of
fexecve() to start with, but if we want that thing, that's the way
to go.