Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230331123221.3273328-1-roberto.sassu@huaweicloud.com> <20230331123221.3273328-2-roberto.sassu@huaweicloud.com>
In-Reply-To: <20230331123221.3273328-2-roberto.sassu@huaweicloud.com>
From:   Paul Moore <paul@paul-moore.com>
Date:   Tue, 4 Apr 2023 14:25:54 -0400
Message-ID: <CAHC9VhT17mtnncuKVNzqr0zTU+E5R+8wMaxF4AYXS_bG9L0HZQ@mail.gmail.com>
Subject: Re: [PATCH v10 1/4] reiserfs: Add security prefix to xattr name in reiserfs_security_write()
To:     Roberto Sassu <roberto.sassu@huaweicloud.com>
Cc:     zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, jmorris@namei.org,
        serge@hallyn.com, stephen.smalley.work@gmail.com,
        eparis@parisplace.org, casey@schaufler-ca.com,
        reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
        bpf@vger.kernel.org, kpsingh@kernel.org, keescook@chromium.org,
        nicolas.bouchinet@clip-os.org,
        Roberto Sassu <roberto.sassu@huawei.com>,
        stable@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Fri, Mar 31, 2023 at 8:33=E2=80=AFAM Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> Reiserfs sets a security xattr at inode creation time in two stages: firs=
t,
> 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 th=
e
> 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@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@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 :)

--=20
paul-moore.com