linux-kernel - Re: [PATCH v5 00/39] Shadow stacks for userspace

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Message-ID: <eeb060d5-4a90-ee92-91c3-af94a57a2859@amd.com>
Date:   Fri, 20 Jan 2023 11:48:25 -0600
From:   John Allen <john.allen@....com>
To:     Rick Edgecombe <rick.p.edgecombe@...el.com>, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
        Arnd Bergmann <arnd@...db.de>,
        Andy Lutomirski <luto@...nel.org>,
        Balbir Singh <bsingharora@...il.com>,
        Borislav Petkov <bp@...en8.de>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Eugene Syromiatnikov <esyr@...hat.com>,
        Florian Weimer <fweimer@...hat.com>,
        "H . J . Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Weijiang Yang <weijiang.yang@...el.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        kcc@...gle.com, eranian@...gle.com, rppt@...nel.org,
        jamorris@...ux.microsoft.com, dethoma@...rosoft.com,
        akpm@...ux-foundation.org, Andrew.Cooper3@...rix.com,
        christina.schimpe@...el.com
Subject: Re: [PATCH v5 00/39] Shadow stacks for userspace

On 1/19/23 3:22 PM, Rick Edgecombe wrote:
> I left tested-by tags in place per discussion with testers. Testers, please
> retest.

Re-tested on my AMD system (Dell PowerEdge R6515 w/ EPYC 7713) and it looks
like everything is still working properly.

The selftests seem to run cleanly:

[INFO]	new_ssp = 7ff19be0dff8, *new_ssp = 7ff19be0e001
[INFO]	changing ssp from 7ff19c7f1ff0 to 7ff19be0dff8
[INFO]	ssp is now 7ff19be0e000
[OK]	Shadow stack pivot
[OK]	Shadow stack faults
[INFO]	Corrupting shadow stack
[INFO]	Generated shadow stack violation successfully
[OK]	Shadow stack violation test
[INFO]	Gup read -> shstk access success
[INFO]	Gup write -> shstk access success
[INFO]	Violation from normal write
[INFO]	Gup read -> write access success
[INFO]	Violation from normal write
[INFO]	Gup write -> write access success
[INFO]	Cow gup write -> write access success
[OK]	Shadow gup test
[INFO]	Violation from shstk access
[OK]	mprotect() test
[OK]	Userfaultfd test
[OK]	32 bit test

Additionally, I could see the control protection messages in dmesg when
running the shstk violation test from here:
https://gitlab.com/cet-software/cet-smoke-test

ld-linux-x86-64[99764] control protection ip:401139 sp:7fff025507d8 ssp:7f186e017fd8 error:1(near ret) in shstk1[401000+1000]

Tested-by: John Allen <john.allen@....com>