linux-kernel - Re: [PATCH] generic/381: enable on systems which allows usernames that begin with digits

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Date:   Thu, 21 Dec 2017 18:48:23 +0100
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Eryu Guan <eguan@...hat.com>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>, fstests@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] generic/381: enable on systems which allows usernames
 that begin with digits

On Thu, Dec 21, 2017 at 04:23:42PM +0800, Eryu Guan wrote:
> On Fri, Dec 15, 2017 at 12:41:07PM -0800, Luis R. Rodriguez wrote:
> > Some systems are not allowing usernames prefixed with a number now, this
> > test however relies on the assumption that you can end up with usernames
> > of such type, given the purpose of the test is to ensure that xfs_quota
> > can differentiate between UIDs and names beginning with numbers.
> > 
> > systemd >= 232 (circa 2017) no longer allows usernames starting with digits
> > [0], there is a systemd exploit (CVE-2017-1000082 [1]) for why that was done,
> > however even upstream shadow useradd also does not allow similar user types
> > since shadow version v4.0.1 (circa 2007) [2] but there no easy way to check
> > shadow's useradd's version.
> > 
> > You can still shoehorn in these types of users by manually editing files,
> > but that's just shooting yourself on the foot given all the precautions
> > taken now by userspace, so just check for the systemd version for now as
> > requirement for running this test.
> > 
> > [0] https://github.com/systemd/systemd/issues/6237
> > [1] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-1000082
> > [2] https://github.com/shadow-maint/shadow/commit/9db6abfa42c946b4046f4b2fe67dc43ba862eb0e
> > 
> > Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
> > ---
> >  README            |  7 +++++--
> >  common/config     |  1 +
> >  common/rc         | 42 ++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/381 |  1 +
> >  4 files changed, 49 insertions(+), 2 deletions(-)
> > 
> > diff --git a/README b/README
> > index ed69332e774e..aff7bdae7cb4 100644
> > --- a/README
> > +++ b/README
> > @@ -20,8 +20,11 @@ _______________________
> >  - run make
> >  - run make install
> >  - create fsgqa test user ("sudo useradd fsgqa")
> > -- create 123456-fsgqa test user ("sudo useradd 123456-fsgqa")
> > -	
> > +- Only on systems which allow usernames that start with a digit (older
> > +  than  systemd 232 and/or has shadow older than v4.0.1), create the
> > +  123456-fsgqa test user:
> > +    sudo useradd 123456-fsgqa
> > +
> 
> IMHO, this doc update is sufficient, generic/381 already _notrun if
> there's no 123456-fsgqa user present because of
> 
> _require_user 123456-fsgqa

I think the output with the patch is *much* clearer and to the point,
it requires less work on the folks analyzing results. Otherwise the
results are not clear and only if the user read the README or the
brief of the test would be very clear why the test could not run.

> And we don't rely on any version check in fstests, usually we check on
> the actual behavior, e.g. actually mkfs & mount the fs to see if the
> current kernel and userspace support a given feature.

We do check for a version check for mkfs, one test only runs on older
mkfs versions.

  Luis