From: Dave Hansen <dave.hansen@intel.com>
To: Jeff Xu <jeffxu@google.com>
Cc: jeffxu@chromium.org, luto@kernel.org, jorgelo@chromium.org,
keescook@chromium.org, groeck@chromium.org, jannh@google.com,
sroettger@google.com, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 2/6] PKEY: Add arch_check_pkey_enforce_api()
Date: Thu, 18 May 2023 17:00:01 -0700 [thread overview]
Message-ID: <c53c03e8-529f-5b72-42ab-f32f50aaab35@intel.com> (raw)
In-Reply-To: <CALmYWFtu-WzOTEs2aWU3zMW=KZUjaaL7OTE7hQtHjfwQfQNyEA@mail.gmail.com>
On 5/18/23 15:51, Jeff Xu wrote:
>> Do you have a solid handle on all call paths that will reach
>> __arch_check_vma_pkey_for_write() and can you ensure they are all
>> non-remote?
> Is this about the attack scenario where the attacker uses ptrace()
> into the chrome process ? if so it is not in our threat model, and
> that is more related to sandboxing on the host.
The attacker would use *some* remote interface. ptrace() is just one of
those remote interfaces.
> Or is this about io_uring? Yes, io_uring kernel thread breaks our
> expectations of PKRU & user space threads, however I thought the break
> is not just for this - any syscall involved in memory operation will
> break after into io_uring ?
I'm not quite following.
Please just do me a favor: have the io_uring maintainers look at your
proposal. Make sure that the defenses you are building can work in a
process where io_uring is in use by the benign threads.
Those same folks are pretty familiar with the other, more traditional
I/O syscalls that have in-memory descriptors that control syscall
behavior like readv/writev. Those also need a close look.
> Other than those, yes, I try to ensure the check is only used at the
> beginning of syscall entry in all cases, which should be non-remote I
> hope.
You're right that synchronous, shallow syscall paths are usually
non-remote. But those aren't the problem. The problem is that there
*ARE* remote accesses and those are a potential hole for this whole
mechanism.
Can they be closed? I don't know. I honestly don't have a great grasp
on how widespread these things are. You'll need a much more complete
grasp on them than I have before this thing can go forward.
next prev parent reply other threads:[~2023-05-19 0:00 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-15 13:05 [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1 jeffxu
2023-05-15 13:05 ` [PATCH 1/6] PKEY: Introduce PKEY_ENFORCE_API flag jeffxu
2023-05-16 23:14 ` Dave Hansen
2023-05-16 23:55 ` Jeff Xu
2023-05-17 11:07 ` Stephen Röttger
2023-05-15 13:05 ` [PATCH 2/6] PKEY: Add arch_check_pkey_enforce_api() jeffxu
2023-05-18 21:43 ` Dave Hansen
2023-05-18 22:51 ` Jeff Xu
2023-05-19 0:00 ` Dave Hansen [this message]
2023-05-19 11:22 ` Stephen Röttger
2023-05-15 13:05 ` [PATCH 3/6] PKEY: Apply PKEY_ENFORCE_API to mprotect jeffxu
2023-05-16 20:07 ` Kees Cook
2023-05-16 22:23 ` Jeff Xu
2023-05-16 23:18 ` Dave Hansen
2023-05-16 23:36 ` Jeff Xu
2023-05-17 4:50 ` Jeff Xu
2023-05-15 13:05 ` [PATCH 4/6] PKEY:selftest pkey_enforce_api for mprotect jeffxu
2023-05-15 13:05 ` [PATCH 5/6] KEY: Apply PKEY_ENFORCE_API to munmap jeffxu
2023-05-16 20:06 ` Kees Cook
2023-05-16 22:24 ` Jeff Xu
2023-05-16 23:23 ` Dave Hansen
2023-05-17 0:08 ` Jeff Xu
2023-05-15 13:05 ` [PATCH 6/6] PKEY:selftest pkey_enforce_api for munmap jeffxu
2023-05-15 14:28 ` [PATCH 0/6] Memory Mapping (VMA) protection using PKU - set 1 Dave Hansen
2023-05-16 7:06 ` Stephen Röttger
2023-05-16 22:41 ` Dave Hansen
2023-05-17 10:51 ` Stephen Röttger
2023-05-17 15:07 ` Dave Hansen
2023-05-17 15:21 ` Jeff Xu
2023-05-17 15:29 ` Dave Hansen
2023-05-17 23:48 ` Jeff Xu
2023-05-18 15:37 ` Dave Hansen
2023-05-18 20:20 ` Jeff Xu
2023-05-18 21:04 ` Dave Hansen
2023-05-19 11:13 ` Stephen Röttger
2023-05-24 20:15 ` Jeff Xu
2023-06-01 1:39 ` Jeff Xu
2023-06-01 16:16 ` Dave Hansen
2023-05-31 23:02 ` Jeff Xu
2023-05-16 20:08 ` Kees Cook
2023-05-16 22:17 ` Jeff Xu
2023-05-16 22:30 ` Dave Hansen
2023-05-16 23:39 ` Jeff Xu
2023-05-17 10:49 ` Stephen Röttger
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