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Re: [Qemu-devel] [PATCH v2 10/28] 9pfs: local: lremovexattr: don't follo
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v2 10/28] 9pfs: local: lremovexattr: don't follow symlinks |
Date: |
Mon, 27 Feb 2017 13:12:40 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Sun, Feb 26, 2017 at 11:42:51PM +0100, Greg Kurz wrote:
> The local_lremovexattr() callback is vulnerable to symlink attacks because
> it calls lremovexattr() which follows symbolic links in all path elements
> but the rightmost one.
>
> This patch introduces a helper to emulate the non-existing fremovexattrat()
> function: it is implemented with /proc/self/fd which provides a trusted
> path that can be safely passed to lremovexattr().
>
> local_lremovexattr() is converted to use this helper and opendir_nofollow().
>
> This partly fixes CVE-2016-9602.
>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> v2: - introduce /proc based fremovexattrat_nofollow()
> - fix arguments passed to local_removexattr_nofollow()
> ---
> hw/9pfs/9p-posix-acl.c | 10 ++--------
> hw/9pfs/9p-xattr-user.c | 8 +-------
> hw/9pfs/9p-xattr.c | 36 +++++++++++++++++++++++++++++++-----
> hw/9pfs/9p-xattr.h | 2 ++
> 4 files changed, 36 insertions(+), 20 deletions(-)
Reviewed-by: Stefan Hajnoczi <address@hidden>
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- [Qemu-devel] [PATCH v2 05/28] 9pfs: local: keep a file descriptor on the shared folder, (continued)
- [Qemu-devel] [PATCH v2 05/28] 9pfs: local: keep a file descriptor on the shared folder, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 06/28] 9pfs: local: open/opendir: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 07/28] 9pfs: local: lgetxattr: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 08/28] 9pfs: local: llistxattr: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 09/28] 9pfs: local: lsetxattr: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 10/28] 9pfs: local: lremovexattr: don't follow symlinks, Greg Kurz, 2017/02/26
- Re: [Qemu-devel] [PATCH v2 10/28] 9pfs: local: lremovexattr: don't follow symlinks,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v2 11/28] 9pfs: local: unlinkat: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 12/28] 9pfs: local: remove: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 13/28] 9pfs: local: utimensat: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 14/28] 9pfs: local: statfs: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 15/28] 9pfs: local: truncate: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 16/28] 9pfs: local: readlink: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 17/28] 9pfs: local: lstat: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 18/28] 9pfs: local: renameat: don't follow symlinks, Greg Kurz, 2017/02/26
- [Qemu-devel] [PATCH v2 19/28] 9pfs: local: rename: use renameat, Greg Kurz, 2017/02/26