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From: David Howells <dhowells@redhat.com>
To: Paul Moore <paul@paul-moore.com>
Cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna@kernel.org>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	Eric Paris <eparis@parisplace.org>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Scott Mayhew <smayhew@redhat.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nfs@vger.kernel.org, linux-security-module@vger.kernel.org,
	selinux@vger.kernel.org
Subject: Re: [PATCH v6] vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing
Date: Fri, 04 Aug 2023 16:22:27 +0100	[thread overview]
Message-ID: <2680108.1691162547@warthog.procyon.org.uk> (raw)
In-Reply-To: <2678222.1691162178@warthog.procyon.org.uk>

David Howells <dhowells@redhat.com> wrote:

> IIRC, the issue is when you make a mount with an explicit context= setting and
> make another mount from some way down the export tree that doesn't have an
> explicit setting, e.g.:
> 
> 	mount carina:/ /mnt -o context=system_u:object_r:root_t:s0
> 	mount carina:/nfs/scratch /mnt2
> 
> and then cause an automount to walk from one to the other:
> 
> 	stat /mnt/nfs/scratch/foo

Actually, the order there isn't quite right.  The problem is with this order:

	# mount carina:/ /mnt -o context=system_u:object_r:root_t:s0
	# stat /mnt/nfs/scratch/bus
	  File: /mnt/nfs/scratch/bus
	  Size: 124160          Blocks: 248        IO Block: 1048576 regular file
	Device: 0,55    Inode: 131         Links: 1
	...
	# mount carina:/nfs/scratch /mnt2
	mount.nfs: /mnt2 is busy or already mounted or sharecache fail

with the error:

	SELinux: mount invalid.  Same superblock, different security settings for (dev 0:52, type nfs4)

David


  parent reply	other threads:[~2023-08-04 15:23 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-02 16:49 [PATCH v6] vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing Jeff Layton
2023-08-02 18:16 ` Paul Moore
2023-08-02 19:34   ` Jeff Layton
2023-08-03  2:46     ` Paul Moore
2023-08-03 16:27       ` Jeff Layton
2023-08-04  2:48         ` Paul Moore
2023-08-04 12:58           ` Jeff Layton
2023-08-03 13:27     ` Christian Brauner
2023-08-03 16:09       ` Jeff Layton
2023-08-03 17:36         ` Christian Brauner
2023-08-03 18:58           ` Jeff Layton
2023-08-04  8:25             ` Christian Brauner
2023-08-04 13:25               ` Jeff Layton
2023-08-04 13:38                 ` Christian Brauner
2023-08-04 15:16 ` David Howells
2023-08-04 15:22 ` David Howells [this message]
2023-08-04 16:00   ` Jeff Layton

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