linux-kernel - Re: [PATCH v2 02/12] mm: introduce execmem_text_alloc() and jit_text

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: <CAPhsuW4pDkd7rCWRM6938ve36rfhGxyu=8t1-GjcKnNajofpQA@mail.gmail.com>
Date:   Mon, 26 Jun 2023 10:48:37 -0700
From:   Song Liu <song@...nel.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Mike Rapoport <rppt@...nel.org>, Andy Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        "David S. Miller" <davem@...emloft.net>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Helge Deller <deller@....de>,
        Huacai Chen <chenhuacai@...nel.org>,
        Kent Overstreet <kent.overstreet@...ux.dev>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nadav Amit <nadav.amit@...il.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Puranjay Mohan <puranjay12@...il.com>,
        Rick P Edgecombe <rick.p.edgecombe@...el.com>,
        "Russell King (Oracle)" <linux@...linux.org.uk>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, bpf@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-mm@...ck.org, linux-modules@...r.kernel.org,
        linux-parisc@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, loongarch@...ts.linux.dev,
        netdev@...r.kernel.org, sparclinux@...r.kernel.org,
        "the arch/x86 maintainers" <x86@...nel.org>
Subject: Re: [PATCH v2 02/12] mm: introduce execmem_text_alloc() and jit_text_alloc()

On Mon, Jun 26, 2023 at 5:31 AM Mark Rutland <mark.rutland@....com> wrote:
>
[...]
> >
> > So the idea was that jit_text_alloc() will have a cache of large pages
> > mapped ROX, will allocate memory from those caches and there will be
> > jit_update() that uses text poking for writing to that memory.
> >
> > Upon allocation of a large page to increase the cache, that large page will
> > be "invalidated" by filling it with breakpoint instructions (e.g int3 on
> > x86)
>
> Does that work on x86?
>
> That is in no way gauranteed for other architectures; on arm64 you need
> explicit cache maintenance (with I-cache maintenance at the VA to be executed
> from) followed by context-synchronization-events (e.g. via ISB instructions, or
> IPIs).

I guess we need:
1) Invalidate unused part of the huge ROX pages;
2) Do not put two jit users (including module text, bpf, etc.) in the
same cache line;
3) Explicit cache maintenance;
4) context-synchronization-events.

Would these (or a subset of them) be sufficient to protect us from torn read?

Thanks,
Song