linux-kernel - Re: [REGRESSION] Re: [PATCH] Revert "vmgenid: emit uevent when VMGENID updates"

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Message-ID: <b819717c-74ea-4556-8577-ccd90e9199e9@amazon.com>
Date: Fri, 26 Apr 2024 13:33:19 +0200
From: Alexander Graf <graf@...zon.com>
To: Lennart Poettering <mzxreary@...inter.de>, "Jason A. Donenfeld"
	<Jason@...c4.com>
CC: <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>, "Greg
 Kroah-Hartman" <gregkh@...uxfoundation.org>, Linus Torvalds
	<torvalds@...ux-foundation.org>, Babis Chalios <bchalios@...zon.es>,
	"Theodore Ts'o" <tytso@....edu>, "Cali, Marco" <xmarcalx@...zon.co.uk>, Arnd
 Bergmann <arnd@...db.de>, "rostedt@...dmis.org" <rostedt@...dmis.org>,
	"Christian Brauner" <brauner@...nel.org>, <linux@...mhuis.info>,
	<regressions@...ts.linux.dev>
Subject: Re: [REGRESSION] Re: [PATCH] Revert "vmgenid: emit uevent when
 VMGENID updates"


On 23.04.24 14:23, Lennart Poettering wrote:
> On Di, 23.04.24 03:21, Jason A. Donenfeld (Jason@...c4.com) wrote:
>
> Jason!
>
> Can you please explain to me what the precise problem is with the
> uevent? It doesn't leak any information about the actual vmgenid, it
> just lets userspace know that the machine was cloned,
> basically. What's the problem with that? I'd really like to
> understand?
>
> There are many usecases for this in the VM world, for example we'd
> like to hook things up so that various userspace managed concepts,
> such as DHCP leases, MAC addresses are automatically refreshed.
>
> This has no relationship to RNGs or anything like this, it's just an
> event we can handle in userspace to trigger address refreshes like
> this.
>
> Hence, why is the revert necessary? This was already in a released
> kernel, and we have started work on making use of this in systemd, and
> afaics this does not compromise the kernel RNG in even the remotest of
> ways, hence why is a revert necessary? From my usersace perspective
> it's just very very sad, that this simple, trivial interface we wanted
> to use, that was in a stable kernel is now gone again.
>
> Can you explain what the problem with this single-line trivial
> interface is? I really would like to understand!


Jason, ping?

If I don't see technical reasoning from you here, I will assume that you 
agree with Lennart and my points of views and send a revert of your 
revert shortly to ensure systemd has its uevent still in 6.9.


Alex




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