linux-kernel - Re: [PATCH] filelocks: use mount idmapping for setlease permission check

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Date:   Thu,  9 Mar 2023 22:40:33 +0100
From:   Christian Brauner <brauner@...nel.org>
To:     Jeff Layton <jlayton@...nel.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
Cc:     Christian Brauner <brauner@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] filelocks: use mount idmapping for setlease permission check

From: Christian Brauner (Microsoft) <brauner@...nel.org>


On Thu, 09 Mar 2023 14:39:09 -0600, Seth Forshee (DigitalOcean) wrote:
> A user should be allowed to take out a lease via an idmapped mount if
> the fsuid matches the mapped uid of the inode. generic_setlease() is
> checking the unmapped inode uid, causing these operations to be denied.
> 
> Fix this by comparing against the mapped inode uid instead of the
> unmapped uid.
> 
> [...]

I've added a Cc: stable@...r.kernel.org so it's clear we should backport this.
But just to note this here right away, this will likely apply cleanly on 5.15
and 6.2 but fail to compile because our internal apis changed. So I'll have to
do a custom backport for 5.15 and 6.2 once we'll get the failure report thingy
from the stable folks. But applied now,

[1/1] filelocks: use mount idmapping for setlease permission check
      commit: 42d0c4bdf753063b6eec55415003184d3ca24f6e