[PATCH v10 1/4] reiserfs: Add security prefix to xattr name in reiserfs_security_write()

[Paul Moore]

On Fri, Mar 31, 2023 at 8:33 AM Roberto Sassu
<roberto.sassu at huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu at huawei.com>
>
> Reiserfs sets a security xattr at inode creation time in two stages: first,
> it calls reiserfs_security_init() to obtain the xattr from active LSMs;
> then, it calls reiserfs_security_write() to actually write that xattr.
>
> Unfortunately, it seems there is a wrong expectation that LSMs provide the
> full xattr name in the form 'security.<suffix>'. However, LSMs always
> provided just the suffix, causing reiserfs to not write the xattr at all
> (if the suffix is shorter than the prefix), or to write an xattr with the
> wrong name.
>
> Add a temporary buffer in reiserfs_security_write(), and write to it the
> full xattr name, before passing it to reiserfs_xattr_set_handle().
>
> Also replace the name length check with a check that the full xattr name is
> not larger than XATTR_NAME_MAX.
>
> Cc: stable at vger.kernel.org # v2.6.x
> Fixes: 57fe60df6241 ("reiserfs: add atomic addition of selinux attributes during inode creation")
> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
> ---
>  fs/reiserfs/xattr_security.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)

This looks good to me, thanks.  While normally I would merge something
like this into the lsm/stable-X.Y branch, I'm going to merge it into
lsm/next to give it a week or two of extra testing.  I think anyone
who is using reiserfs+LSM (doubtful as it looks horribly broken) would
be okay with waiting a few more days at this point :)

-- 
paul-moore.com