linux-kernel - Re: [PATCH] ublk: enforce ublks_max only for unprivileged devices

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Message-ID: <Z8MPux2zzjcr7ipo@fedora>
Date: Sat, 1 Mar 2025 21:46:35 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Uday Shankar <ushankar@...estorage.com>
Cc: Jens Axboe <axboe@...nel.dk>,
	Mike Christie <michael.christie@...cle.com>,
	linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ublk: enforce ublks_max only for unprivileged devices

On Fri, Feb 28, 2025 at 09:31:48PM -0700, Uday Shankar wrote:
> Commit 403ebc877832 ("ublk_drv: add module parameter of ublks_max for
> limiting max allowed ublk dev"), claimed ublks_max was added to prevent
> a DoS situation with an untrusted user creating too many ublk devices.
> If that's the case, ublks_max should only restrict the number of
> unprivileged ublk devices in the system. Enforce the limit only for
> unprivileged ublk devices, and rename variables accordingly. Leave the
> external-facing parameter name unchanged, since changing it may break
> systems which use it (but still update its documentation to reflect its
> new meaning).
> 
> As a result of this change, in a system where there are only normal
> (non-unprivileged) devices, the maximum number of such devices is
> increased to 1 << MINORBITS, or 1048576. That ought to be enough for
> anyone, right?
> 
> Signed-off-by: Uday Shankar <ushankar@...estorage.com>

Looks fine,

Reviewed-by: Ming Lei <ming.lei@...hat.com>


Thanks,
Ming