Date: Thu, 4 Oct 2018 13:36:50 +0200 From: Jann Horn <jannh@...gle.com> To: Jiri Kosina <jikos@...nel.org>, Casey Schaufler <casey.schaufler@...el.com> Cc: Kernel Hardening <kernel-hardening@...ts.openwall.com>, kernel list <linux-kernel@...r.kernel.org>, linux-security-module <linux-security-module@...r.kernel.org>, selinux@...ho.nsa.gov, Dave Hansen <dave.hansen@...el.com>, deneen.t.dock@...el.com, kristen@...ux.intel.com, Arjan van de Ven <arjan@...ux.intel.com> Subject: Re: [PATCH v5 2/5] Smack: Prepare for PTRACE_MODE_SCHED On Thu, Oct 4, 2018 at 9:47 AM Jiri Kosina <jikos@...nel.org> wrote: > On Thu, 27 Sep 2018, Jann Horn wrote: > > > Yes. Since the PTRACE_MODE_NOAUDIT was in PTRACE_MODE_IBPB in Jiri's > > > previous patch set and not in PTRACE_MODE_SCHED in this one I assumed > > > that there was a good reason for it. > > > > Jiri, was there a good reason for it, and if so, what was it? > > [ FWIW PTRACE_MODE_NOAUDIT being in PTRACE_MODE_IBPB goes back to original > Tim's pre-CRD patchset ] > > Well, we can't really call out into audit from scheduler code, and the > previous versions of the patchsets didn't have PTRACE_MODE_SCHED, so it > had to be included in PTRACE_MODE_IBPB in order to make sure we're not > calling into audit from context switch code. > > Or did I misunderstand the question? If I understand Casey correctly, he is saying that your patch (https://lore.kernel.org/lkml/nycvar.YFH.email@example.com/) doesn't include PTRACE_MODE_NOAUDIT for IBPB, but the previous v6 of your patch (https://lore.kernel.org/lkml/nycvar.YFH.firstname.lastname@example.org/) did include it, and therefore Casey thinks that there is a specific reason why you removed PTRACE_MODE_NOAUDIT, and therefore Casey is adding special-case logic for PTRACE_MODE_SCHED to Smack when simply using PTRACE_MODE_NOAUDIT would also work. I think that Casey should change ptrace_may_access_sched() to use "mode | PTRACE_MODE_SCHED | PTRACE_MODE_NOAUDIT".
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