From: Ian Kent <raven@themaw.net>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Aleksa Sarai <cyphar@cyphar.com>,
David Howells <dhowells@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
stable <stable@vger.kernel.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Serge Hallyn <serge@hallyn.com>,
dev@opencontainers.org,
Linux Containers <containers@lists.linux-foundation.org>,
Linux API <linux-api@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 0/1] mount: universally disallow mounting over symlinks
Date: Tue, 14 Jan 2020 13:59:42 +0800 [thread overview]
Message-ID: <1fb8a0e4a763219f0f6cde6023ba89c1774cb854.camel@themaw.net> (raw)
In-Reply-To: <d6cad1552171da1eb38c55d1d7b1ff45902b101f.camel@themaw.net>
On Tue, 2020-01-14 at 13:01 +0800, Ian Kent wrote:
> On Tue, 2020-01-14 at 04:39 +0000, Al Viro wrote:
> > On Tue, Jan 14, 2020 at 08:25:19AM +0800, Ian Kent wrote:
> >
> > > This isn't right.
> > >
> > > There's actually nothing stopping a user from using a direct map
> > > entry that's a multi-mount without an actual mount at its root.
> > > So there could be directories created under these, it's just not
> > > usually done.
> > >
> > > I'm pretty sure I don't check and disallow this.
> >
> > IDGI... How the hell will that work in v5? Who will set _any_
> > traps outside the one in root in that scenario? autofs_lookup()
> > won't (there it's conditional upon indirect mount). Neither
> > will autofs_dir_mkdir() (conditional upon version being less
> > than 5). Who will, then?
> >
> > Confused...
>
> It's easy to miss.
>
> For autofs type direct and offset mounts the flags are set at fill
> super time.
>
> They have to be set then because they are direct mounts and offset
> mounts behave the same as direct mounts so they need to be set then
> too. So, like direct mounts, offset mounts are each distinct autofs
> (trigger) mounts.
>
> I could check for this construct and refuse it if that's really
> needed. I'm pretty sure this map construct isn't much used by
> people using direct mounts.
Ok, once again I'm not exactly accurate is some of what I said.
It turns out that the autofs connectathon tests, one of the tests
that I use, does test direct mounts with offsets both with and
without a real mount at the base of the mount.
Based on that, I have to say this map construct is meant to be
supported with Sun format maps of autofs (even though I think it's
probably not used much).
So not allowing it is probably the wrong thing to do.
OTOH initial testing with the #work.namei branch shows these are
functioning as required.
Ian
next prev parent reply other threads:[~2020-01-14 5:59 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-30 5:20 [PATCH RFC 0/1] mount: universally disallow mounting over symlinks Aleksa Sarai
2019-12-30 5:20 ` [PATCH RFC 1/1] " Aleksa Sarai
2019-12-30 7:34 ` Linus Torvalds
2019-12-30 8:28 ` Aleksa Sarai
2020-01-08 4:39 ` Andy Lutomirski
2019-12-30 5:44 ` [PATCH RFC 0/1] " Al Viro
2019-12-30 5:49 ` Aleksa Sarai
2019-12-30 7:29 ` Aleksa Sarai
2019-12-30 7:53 ` Linus Torvalds
2019-12-30 8:32 ` Aleksa Sarai
2020-01-02 8:58 ` David Laight
2020-01-02 9:09 ` Aleksa Sarai
2020-01-01 0:43 ` Al Viro
2020-01-01 0:54 ` Al Viro
2020-01-01 3:08 ` Al Viro
2020-01-01 14:44 ` Aleksa Sarai
2020-01-01 23:40 ` Al Viro
2020-01-02 3:59 ` Aleksa Sarai
2020-01-03 1:49 ` Al Viro
2020-01-04 4:46 ` Ian Kent
2020-01-08 3:13 ` Al Viro
2020-01-08 3:54 ` Linus Torvalds
2020-01-08 21:34 ` Al Viro
2020-01-10 0:08 ` Linus Torvalds
2020-01-10 4:15 ` Al Viro
2020-01-10 5:03 ` Linus Torvalds
2020-01-10 6:20 ` Ian Kent
2020-01-12 21:33 ` Al Viro
2020-01-13 2:59 ` Ian Kent
2020-01-14 0:25 ` Ian Kent
2020-01-14 4:39 ` Al Viro
2020-01-14 5:01 ` Ian Kent
2020-01-14 5:59 ` Ian Kent [this message]
2020-01-10 21:07 ` Aleksa Sarai
2020-01-14 4:57 ` Al Viro
2020-01-14 5:12 ` Al Viro
2020-01-14 20:01 ` Aleksa Sarai
2020-01-15 14:25 ` Al Viro
2020-01-15 14:29 ` Aleksa Sarai
2020-01-15 14:34 ` Aleksa Sarai
2020-01-15 14:48 ` Al Viro
2020-01-18 12:07 ` [PATCH v3 0/2] openat2: minor uapi cleanups Aleksa Sarai
2020-01-18 12:07 ` [PATCH v3 1/2] open: introduce openat2(2) syscall Aleksa Sarai
2020-01-18 12:08 ` [PATCH v3 2/2] selftests: add openat2(2) selftests Aleksa Sarai
2020-01-18 15:28 ` [PATCH v3 0/2] openat2: minor uapi cleanups Al Viro
2020-01-18 18:09 ` Al Viro
2020-01-18 23:03 ` Aleksa Sarai
2020-01-19 1:12 ` Al Viro
2020-01-15 13:57 ` [PATCH RFC 0/1] mount: universally disallow mounting over symlinks Aleksa Sarai
2020-01-19 3:14 ` [RFC][PATCHSET][CFT] pathwalk cleanups and fixes Al Viro
2020-01-19 3:17 ` [PATCH 01/17] do_add_mount(): lift lock_mount/unlock_mount into callers Al Viro
2020-01-19 3:17 ` [PATCH 02/17] fix automount/automount race properly Al Viro
2020-01-30 14:34 ` Christian Brauner
2020-01-19 3:17 ` [PATCH 03/17] follow_automount(): get rid of dead^Wstillborn code Al Viro
2020-01-30 14:38 ` Christian Brauner
2020-01-19 3:17 ` [PATCH 04/17] follow_automount() doesn't need the entire nameidata Al Viro
2020-01-30 14:45 ` Christian Brauner
2020-01-30 15:38 ` Al Viro
2020-01-30 15:55 ` Al Viro
2020-01-19 3:17 ` [PATCH 05/17] make build_open_flags() treat O_CREAT | O_EXCL as implying O_NOFOLLOW Al Viro
2020-01-19 3:17 ` [PATCH 06/17] handle_mounts(): start building a sane wrapper for follow_managed() Al Viro
2020-01-19 3:17 ` [PATCH 07/17] atomic_open(): saner calling conventions (return dentry on success) Al Viro
2020-01-19 3:17 ` [PATCH 08/17] lookup_open(): " Al Viro
2020-01-19 3:17 ` [PATCH 09/17] do_last(): collapse the call of path_to_nameidata() Al Viro
2020-01-19 3:17 ` [PATCH 10/17] handle_mounts(): pass dentry in, turn path into a pure out argument Al Viro
2020-01-19 3:17 ` [PATCH 11/17] lookup_fast(): consolidate the RCU success case Al Viro
2020-01-19 3:17 ` [PATCH 12/17] teach handle_mounts() to handle RCU mode Al Viro
2020-01-19 3:17 ` [PATCH 13/17] lookup_fast(): take mount traversal into callers Al Viro
2020-01-19 3:17 ` [PATCH 14/17] new step_into() flag: WALK_NOFOLLOW Al Viro
2020-01-19 3:17 ` [PATCH 15/17] fold handle_mounts() into step_into() Al Viro
2020-01-19 3:17 ` [PATCH 16/17] LOOKUP_MOUNTPOINT: fold path_mountpointat() into path_lookupat() Al Viro
2020-01-19 3:17 ` [PATCH 17/17] expand the only remaining call of path_lookup_conditional() Al Viro
2020-01-19 3:17 ` [PATCH 1/9] merging pick_link() with get_link(), part 1 Al Viro
2020-01-19 3:17 ` [PATCH 2/9] merging pick_link() with get_link(), part 2 Al Viro
2020-01-19 3:17 ` [PATCH 3/9] merging pick_link() with get_link(), part 3 Al Viro
2020-01-19 3:17 ` [PATCH 4/9] merging pick_link() with get_link(), part 4 Al Viro
2020-01-19 3:17 ` [PATCH 5/9] merging pick_link() with get_link(), part 5 Al Viro
2020-01-19 3:17 ` [PATCH 6/9] merging pick_link() with get_link(), part 6 Al Viro
2020-01-19 3:17 ` [PATCH 7/9] finally fold get_link() into pick_link() Al Viro
2020-01-19 3:17 ` [PATCH 8/9] massage __follow_mount_rcu() a bit Al Viro
2020-01-19 3:17 ` [PATCH 9/9] new helper: traverse_mounts() Al Viro
2020-01-30 14:13 ` [PATCH 01/17] do_add_mount(): lift lock_mount/unlock_mount into callers Christian Brauner
2020-01-19 14:33 ` [RFC][PATCHSET][CFT] pathwalk cleanups and fixes Ian Kent
2020-01-10 23:19 ` [PATCH RFC 0/1] mount: universally disallow mounting over symlinks Al Viro
2020-01-13 1:48 ` Ian Kent
2020-01-13 3:54 ` Al Viro
2020-01-13 6:00 ` Ian Kent
2020-01-13 6:03 ` Ian Kent
2020-01-13 13:30 ` Al Viro
2020-01-14 7:25 ` Ian Kent
2020-01-14 12:17 ` Ian Kent
2020-01-04 5:52 ` Andy Lutomirski
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