From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm@xmission.com (Eric W. Biederman)
Subject: Re: BUG: Mount ignores mount options
Date: Fri, 10 Aug 2018 20:19:25 -0500
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To: David Howells <dhowells@redhat.com>
Cc: viro@zeniv.linux.org.uk, John Johansen <john.johansen@canonical.com>, Tejun Heo <tj@kernel.org>, selinux@tycho.nsa.gov, Paul Moore <paul@paul-moore.com>, Li Zefan <lizefan@huawei.com>, linux-api@vger.kernel.org, apparmor@lists.ubuntu.com, Casey Schaufler <casey@schaufler-ca.com>, fenghua.yu@intel.com, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Eric Biggers <ebiggers@google.com>, linux-security-module@vger.kernel.org, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, Johannes Weiner <hannes@cmpxchg.org>, Stephen Smalley <sds@tycho.nsa.gov>, tomoyo-dev-en@lists.sourceforge.jp, cgroups@vger.kernel.org, torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y. Ts'o" <tytso@mit.edu>, Miklos Szeredi <miklos@sze>

David Howells <dhowells@redhat.com> writes:

> Eric W. Biederman <ebiederm@xmission.com> wrote:
>
>> There is a serious problem with mount options today that fsopen does not
>> address.  The problem is that mount options are ignored for block based
>> filesystems, and any other type of filesystem that follows the same
>> pattern.
>
> Yes.  Since you *absolutely* *insist* on this being fixed *right* *now* *or*
> *else*, I'm working up a set of additional patches to give userspace the
> option of whether they want no sharing; sharing, but only with exactly the
> same parameters; or to ignore the parameter differences and just accept
> sharing of what's already already mounted (ie. the current behaviour).
>
> The second option, however, is not trivial as it needs to compare the fs
> contexts, including the LSM parameters.  To make that work, I really need to
> remove the old security_mnt_opts stuff - which means I need to port btrfs to
> the new context stuff.
>
> We discussed this yesterday, and I proposed a solution, and I'm working on it.

I repeated this because after some comments from Al on IRC yesterday
and Miklos's email replay. It appeared clear that I had not specified
why my issue was clearly enough for people reading the thread to
understand the problem that I see.

> Yes, I agree it would be nice to have, but it *doesn't* really need supporting
> right this minute, since what I have now oughtn't to break the current
> behaviour.

I am really reluctant to endorse anything that propagates the issues of
the current interface in the new mount interface.

Eric