linux-kernel - Re: [PATCH v6 00/41] Shadow stacks for userspace

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Message-ID: <Y/PWjCAxKcahq98B@johallen-workstation>
Date:   Mon, 20 Feb 2023 14:22:36 -0600
From:   John Allen <john.allen@....com>
To:     Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc:     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, david@...hat.com, debug@...osinc.com
Subject: Re: [PATCH v6 00/41] Shadow stacks for userspace

On Sat, Feb 18, 2023 at 01:13:52PM -0800, Rick Edgecombe wrote:
> I left tested-by tags in place per discussion with testers. Testers, please
> retest.

v6 is still working well on my AMD system (Dell PowerEdge
R6515 w/ EPYC 7713).

The selftests run cleanly:

[INFO]  new_ssp = 7f53069ffff8, *new_ssp = 7f5306a00001
[INFO]  changing ssp from 7f53071ffff0 to 7f53069ffff8
[INFO]  ssp is now 7f5306a00000
[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

And I can 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[51598] control protection ip:401139 sp:7ffd68b1b7c8 ssp:7fb433578fd8 error:1(near ret) in shstk1[401000+1000]

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