linux-kernel - Re: [PATCH 0/4 v5 RESEND] devpts: handle bind-mounts correctly

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Message-ID: <87o9jr285m.fsf@xmission.com>
Date:   Tue, 13 Mar 2018 12:32:37 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Christian Brauner <christian.brauner@...ntu.com>
Cc:     viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
        torvalds@...ux-foundation.org, gregkh@...uxfoundation.org,
        containers@...ts.linux-foundation.org
Subject: Re: [PATCH 0/4 v5 RESEND] devpts: handle bind-mounts correctly

Christian Brauner <christian.brauner@...ntu.com> writes:

> Resending to CC grekh.



Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>

And the first two patches can also have
Reviewed-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Greg this patchset looks read or just about ready to be merged.  Do you
want to take this through your tty tree or should I take it through my
tree.

Eric



>
> Hey everyone,
>
> This is the fith iteration of this patch. Per-patch changes are
> summarized in the individual patches:
>
> ChangeLog v4->v5:
> * added non-functional patch to document devpts_mntget().
>   Reason for putting this in a separate patch is that it allows you,
>   Linus and Eric, to simply drop it if judged useless.
> * reverse error handling logic to further simplify
> * dput() dentry in the non-function patch. This was not really a problem
>   since the following patch included a fix for it. But better to get it
>   right in all individual patches.
> * I did another rewrite of the problem analysis for
>   posterity in the patch "Subject: [PATCH 2/3 v3] devpts: resolve devpts
>   bind-mounts" and in this cover letter.
>
> ChangeLog v3->v4:
> * small logical simplifications
> * add test that bind-mounts of /dev/pts/ptmx to locations that do not
>   resolve to a valid slave pty path under the originating devpts mount
>   fail
>
> ChangeLog v2->v3:
> * rewritten commit message to thoroughly analyse the problem for
>   posterity in the patch "Subject: [PATCH 2/3 v3] devpts: resolve devpts
>   bind-mounts" and in this cover letter.
> * extended selftests to test for correct handling of /dev/pts/ptmx
>   bind-mounts to /dev/ptmx and non-standard devpts mounts such as
>   mount -t devpts devpts /mnt
>
> ChangeLog v1->v2:
> * see individual patches
> ChangeLog v0->v1:
> * see individual patches
>
> Christian Brauner (4):
>   devpts: hoist out check for DEVPTS_SUPER_MAGIC
>   devpts: resolve devpts bind-mounts
>   devpts: comment devpts_mntget()
>   selftests: add devpts selftests
>
>  fs/devpts/inode.c                                |  66 +++--
>  tools/testing/selftests/Makefile                 |   1 +
>  tools/testing/selftests/filesystems/.gitignore   |   1 +
>  tools/testing/selftests/filesystems/Makefile     |   2 +-
>  tools/testing/selftests/filesystems/devpts_pts.c | 313 +++++++++++++++++++++++
>  5 files changed, 363 insertions(+), 20 deletions(-)
>  create mode 100644 tools/testing/selftests/filesystems/devpts_pts.c