linux-kernel - Re: [PATCH] init: Add support for rootwait timeout parameter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 30 May 2023 11:45:00 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Loic Poulain <loic.poulain@...aro.org>
Cc:     corbet@....net, viro@...iv.linux.org.uk,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] init: Add support for rootwait timeout parameter

On Fri, May 26, 2023 at 03:07:16PM +0200, Loic Poulain wrote:
> Add an optional timeout arg to 'rootwait' as the maximum time in
> seconds to wait for the root device to show up before attempting
> forced mount of the root filesystem.
> 
> This can be helpful to force boot failure and restart in case the
> root device does not show up in time, allowing the bootloader to
> take any appropriate measures (e.g. recovery, A/B switch, retry...).
> 
> In success case, mounting happens as soon as the root device is ready,
> contrary to the existing 'rootdelay' parameter (unconditional delay).
> 
> Signed-off-by: Loic Poulain <loic.poulain@...aro.org>
> ---

Not terribly opposed and not terribly convinced yet.
So, we have rootdelay= with a timeout parameter that allows to specify a
delay before attempting to mount the root device. And we have rootwait
currently as an indefinite wait. Adding a timeout for rootwait doesn't
seem crazy and is backwards compatible. But there's no mention of any
concrete users or use-case for this which is usually preferable. If this
is just "could be useful for someone eventually" it's way less desirable
to merge this than when it's "here's a/multiple user/users"... So I
would love to see a use-case described here.

And this is only useful if there isn't an early userspace init that
parses and manages root=. So we need to hit prepare_namespaces() as a
rootwait timeout isn't meaningful if this is done by and early init in
the initramfs for example.