linux-kernel - Re: [PATCH v5 18/39] mm: Handle faultless write upgrades for shstk

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: <fb8446af-fd87-5609-05bf-5064615c7918@redhat.com>
Date:   Wed, 1 Feb 2023 19:03:49 +0100
From:   David Hildenbrand <david@...hat.com>
To:     "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "bsingharora@...il.com" <bsingharora@...il.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "Syromiatnikov, Eugene" <esyr@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "Eranian, Stephane" <eranian@...gle.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "fweimer@...hat.com" <fweimer@...hat.com>,
        "nadav.amit@...il.com" <nadav.amit@...il.com>,
        "jannh@...gle.com" <jannh@...gle.com>,
        "dethoma@...rosoft.com" <dethoma@...rosoft.com>,
        "kcc@...gle.com" <kcc@...gle.com>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "pavel@....cz" <pavel@....cz>,
        "andrew.cooper3@...rix.com" <andrew.cooper3@...rix.com>,
        "hjl.tools@...il.com" <hjl.tools@...il.com>,
        "Yang, Weijiang" <weijiang.yang@...el.com>,
        "oleg@...hat.com" <oleg@...hat.com>,
        "Lutomirski, Andy" <luto@...nel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "jamorris@...ux.microsoft.com" <jamorris@...ux.microsoft.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "Schimpe, Christina" <christina.schimpe@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "mike.kravetz@...cle.com" <mike.kravetz@...cle.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "john.allen@....com" <john.allen@....com>,
        "rppt@...nel.org" <rppt@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "corbet@....net" <corbet@....net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "gorcunov@...il.com" <gorcunov@...il.com>
Cc:     "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
Subject: Re: [PATCH v5 18/39] mm: Handle faultless write upgrades for shstk

On 01.02.23 18:32, Edgecombe, Rick P wrote:
> On Wed, 2023-02-01 at 10:03 +0100, David Hildenbrand wrote:
>>>
>>> The other problem is that one of NULL passers is not for kernel
>>> memory.
>>> huge_pte_mkwrite() calls pte_mkwrite(). Shadow stack memory can't
>>> be
>>> created with MAP_HUGETLB, so it is not needed. Using
>>> pte_mkwrite_kernel() would look weird in this case, but making
>>> huge_pte_mkwrite() take a VMA would be for no reason. Maybe making
>>> huge_pte_mkwrite() take a VMA is the better of those two options.
>>> Or
>>> keep the NULL semantics...  Any thoughts?
>>
>> Well, the reason would be consistency. From a core-mm point of view
>> it
>> makes sense to handle this all consistency, even if the single user
>> (x86) wouldn't strictly require it right now.
>>
>> I'd just pass in the VMA and call it a day :)
> 
> Ok, I'll give it a spin.

It would be good to get more opinions on that, but I'm afraid we won't 
get more deep down in this thread :)

-- 
Thanks,

David / dhildenb