linux-kernel - Re: d_path() and overlay fs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+5PVA6P3cEy9L+PngXdkVki=x32jZmtPJ2b5oT6SLL=U1NAnw@mail.gmail.com>
Date:	Fri, 20 Mar 2015 09:41:25 -0400
From:	Josh Boyer <jwboyer@...oraproject.org>
To:	Karel Zak <kzak@...hat.com>
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	Miklos Szeredi <miklos@...redi.hu>,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: d_path() and overlay fs

On Fri, Mar 20, 2015 at 9:29 AM, Karel Zak <kzak@...hat.com> wrote:
>
>  Hi,
>
>  kernel-4.0.0-0.rc4.git1.3.fc23 (I have nothing more recent right now,
>  sorry it the problem is already fixed).

That equates to Linux v4.0-rc4-88-g7b09ac704bac upstream.

Fedora has Linux v4.0-rc4-199-gb314acaccd7e queued to build today,
which does include an overlayfs fix pull but I have no idea if it
solves the issue.

josh

>
>  It seems like d_path() kernel function returns nonsenses for overlay fs.
>
>  Example:
>
>    # mount -t overlay overlay -olowerdir=/mnt/low,upperdir=/mnt/up/data,workdir=/mnt/up/work /mnt/merged
>    # dd if=/dev/zero of=/mnt/merged/image count=1 bs=1MiB
>
>    # losetup -f /mnt/merged/image
>
>    # cat /sys/block/loop0/loop/backing_file
>    /image
>
>
>  ...should be /mnt/merged/image.
>
>  drivers/block/loop.c: loop_attr_backing_file_show() uses d_path()
>
>  It seems like serious problem because kernel uses d_path() (and
>  friends) on many places to generate path strings for userspace in
>  /proc and /sys and people already use overlay fs in containers.
>
>  Another example:
>
>    # cat /proc/swaps
>    Filename               Type        Size    Used    Priority
>    /dev/sda6              partition   8191996 258308  -1
>    /image                 file        1020    0       -2
>
>
>     Karel
>
> --
>  Karel Zak  <kzak@...hat.com>
>  http://karelzak.blogspot.com
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/