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Re: [Qemu-devel] [PATCH 24/29] 9pfs: local: chown: don't follow symlinks
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 24/29] 9pfs: local: chown: don't follow symlinks |
Date: |
Thu, 23 Feb 2017 15:10:49 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Mon, Feb 20, 2017 at 03:42:26PM +0100, Greg Kurz wrote:
> The local_chown() callback is vulnerable to symlink attacks because it
> calls:
>
> (1) lchown() which follows symbolic links for all path elements but the
> rightmost one
> (2) local_set_xattr()->setxattr() which follows symbolic links for all
> path elements
> (3) local_set_mapped_file_attr() which calls in turn local_fopen() and
> mkdir(), both functions following symbolic links for all path
> elements but the rightmost one
>
> This patch converts local_chown() to rely on open_nofollow() and
> fchownat() to fix (1), as well as local_set_xattrat() and
> local_set_mapped_file_attrat() to fix (2) and (3) respectively.
>
> This partly fixes CVE-2016-9602.
>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
> hw/9pfs/9p-local.c | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
Reviewed-by: Stefan Hajnoczi <address@hidden>
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- Re: [Qemu-devel] [PATCH 19/29] 9pfs: local: renameat: don't follow symlinks, (continued)
- [Qemu-devel] [PATCH 20/29] 9pfs: local: rename: use renameat, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 21/29] 9pfs: local: improve error handling in link op, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 22/29] 9pfs: local: link: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 23/29] 9pfs: local: chmod: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 24/29] 9pfs: local: chown: don't follow symlinks, Greg Kurz, 2017/02/20
- Re: [Qemu-devel] [PATCH 24/29] 9pfs: local: chown: don't follow symlinks,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH 25/29] 9pfs: local: symlink: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 26/29] 9pfs: local: mknod: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 27/29] 9pfs: local: mkdir: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 28/29] 9pfs: local: open2: don't follow symlinks, Greg Kurz, 2017/02/20
- [Qemu-devel] [PATCH 29/29] 9pfs: local: drop unused code, Greg Kurz, 2017/02/20