Re: [PATCH] tmpfs: clear S_ISGID when setting posix ACLs

From: Jan Kara
Date: Tue Jan 10 2017 - 03:03:07 EST


On Mon 09-01-17 09:34:48, Gu Zheng wrote:
> This change was missed the tmpfs modification in In CVE-2016-7097
> commit 073931017b49 ("posix_acl: Clear SGID bit when setting
> file permissions")
> It can test by xfstest generic/375, which failed to clear
> setgid bit in the following test case on tmpfs:
>
> touch $testfile
> chown 100:100 $testfile
> chmod 2755 $testfile
> _runas -u 100 -g 101 -- setfacl -m u::rwx,g::rwx,o::rwx $testfile
>
> Signed-off-by: Gu Zheng <guzheng1@xxxxxxxxxx>

Thanks. The patch looks good. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Al, will you please merge it? Thanks!

Honza

> ---
> fs/posix_acl.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/fs/posix_acl.c b/fs/posix_acl.c
> index 5955220..d014dff 100644
> --- a/fs/posix_acl.c
> +++ b/fs/posix_acl.c
> @@ -922,11 +922,10 @@ int simple_set_acl(struct inode *inode, struct posix_acl *acl, int type)
> int error;
>
> if (type == ACL_TYPE_ACCESS) {
> - error = posix_acl_equiv_mode(acl, &inode->i_mode);
> - if (error < 0)
> - return 0;
> - if (error == 0)
> - acl = NULL;
> + error = posix_acl_update_mode(inode,
> + &inode->i_mode, &acl);
> + if (error)
> + return error;
> }
>
> inode->i_ctime = current_time(inode);
> --
> 2.5.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR