linux-kernel - Re: [PATCH 2/2] LSM: SafeSetID: Add setgroups() security policy handling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJ-EccN92u8y46j+h1Vg8tzFfRDynMM=1zRF6zGjx_4qKJ=AbQ@mail.gmail.com>
Date:   Tue, 14 Jun 2022 10:36:59 -0700
From:   Micah Morton <mortonm@...omium.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-security-module@...r.kernel.org, jmorris@...ei.org,
        serge@...lyn.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] LSM: SafeSetID: Add setgroups() security policy handling

On Mon, Jun 13, 2022 at 4:46 PM Kees Cook <keescook@...omium.org> wrote:
>
> On Mon, Jun 13, 2022 at 02:00:03PM -0700, Micah Morton wrote:
> > On Mon, Jun 13, 2022 at 1:28 PM Micah Morton <mortonm@...omium.org> wrote:
> > [...]
> > > +static int safesetid_task_fix_setgroups(struct cred *new, const struct cred *old)
> > > +{
> > > +       int i;
> > > +
> > > +       /* Do nothing if there are no setgid restrictions for our old RGID. */
> > > +       if (setid_policy_lookup((kid_t){.gid = old->gid}, INVALID_ID, GID) == SIDPOL_DEFAULT)
> > > +               return 0;
> > > +
> > > +       get_group_info(new->group_info);
> > > +       for (i = 0; i < new->group_info->ngroups; i++) {
> > > +               if (!id_permitted_for_cred(old, (kid_t){.gid = group_info->gid[i]}, GID)) {
> >
> > Oops, should be:
> >
> > !id_permitted_for_cred(old, (kid_t){.gid = new->group_info->gid[i]}, GID)
> >
> > Guess I won't send a whole new patch just for that one line
>
> This begs the question: are there self-tests for this LSM somewhere?
> It'd be really nice to add them to tool/testing/selftests ...

There actually is tools/testing/selftests/safesetid/ but I haven't
updated it since v1 of SafeSetID that only accommodated UIDs. I've
been relying on integration testing we have out of tree on the Chrome
OS side but I suppose its reasonable to bring the selftest up to date
as well :)

Also both patches are a couple lines off from the ones I was finished
developing/testing with.. some kind of screw up happened when I copied
from my dev machine to another where I could get git-send-email
working properly. I'll just resend these 2 patches along with the
update to the selftest.

Thanks

>
> --
> Kees Cook