linux-kernel - Re: [PATCH v4 07/39] x86: Add user control-protection fault handler

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: <Y7V2AjJsfBnk4Ibx@zn.tnic>
Date:   Wed, 4 Jan 2023 13:50:10 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
Cc:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "kcc@...gle.com" <kcc@...gle.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "Lutomirski, Andy" <luto@...nel.org>,
        "nadav.amit@...il.com" <nadav.amit@...il.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Schimpe, Christina" <christina.schimpe@...el.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "corbet@....net" <corbet@....net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dethoma@...rosoft.com" <dethoma@...rosoft.com>,
        "jannh@...gle.com" <jannh@...gle.com>,
        "x86@...nel.org" <x86@...nel.org>, "pavel@....cz" <pavel@....cz>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "rppt@...nel.org" <rppt@...nel.org>,
        "jamorris@...ux.microsoft.com" <jamorris@...ux.microsoft.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "john.allen@....com" <john.allen@....com>,
        "bsingharora@...il.com" <bsingharora@...il.com>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "oleg@...hat.com" <oleg@...hat.com>,
        "andrew.cooper3@...rix.com" <andrew.cooper3@...rix.com>,
        "Yu, Yu-cheng" <yu-cheng.yu@...el.com>,
        "gorcunov@...il.com" <gorcunov@...il.com>,
        "fweimer@...hat.com" <fweimer@...hat.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "mtk.manpages@...il.com" <mtk.manpages@...il.com>,
        "hjl.tools@...il.com" <hjl.tools@...il.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Syromiatnikov, Eugene" <esyr@...hat.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "Yang, Weijiang" <weijiang.yang@...el.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "Eranian, Stephane" <eranian@...gle.com>
Subject: Re: [PATCH v4 07/39] x86: Add user control-protection fault handler

On Wed, Dec 21, 2022 at 09:42:50PM +0000, Edgecombe, Rick P wrote:
> Oh, you mean the whole Kconfig thing. Yea, I mean I see the point about
> typical configs. But at least CONFIG_X86_CET seems consistent with
> CONFIG_INTEL_TDX_GUEST, CONFIG_IOMMU_SVA, etc.
> 
> What about moving it out of traps.c to a cet.c, like
> exc_vmm_communication for CONFIG_AMD_MEM_ENCRT? Then the inclusion
> logic lives in the build files, instead of an ifdef.

Yeah, that definitely sounds cleaner. Another example would be the #MC handler
being in mce code and not in traps.c.

So yeah, the reason why I'm even mentioning this is that I get an allergic
reaction when I see unwieldy ifdeffery in one screen worth of code. But this is
just me. :)

> One aspect that has come up a couple of times, is how closely related
> all these CET features are (or aren't). Shadow stack and IBT are mostly
> separate, but do share an xfeature and an exception type. Similarly for
> supervisor and user mode support for either of the CET features. So
> maybe that is what is unusual here. There are some aspects that make
> them look like separate features, which leads people to think they
> should be separate in the code. But actually separating them leads to
> excess ifdefery.

Yeah, I think you solved that correctly by having the common X86_CET symbol
selected by the two.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette