From: Kees Cook <keescook@chromium.org>
To: jeffxu@chromium.org
Cc: skhan@linuxfoundation.org, akpm@linux-foundation.org,
dmitry.torokhov@gmail.com, dverkamp@chromium.org,
hughd@google.com, jeffxu@google.com, jorgelo@chromium.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, jannh@google.com,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH v6 4/6] mm/memfd: Add write seals when apply SEAL_EXEC to executable memfd
Date: Thu, 8 Dec 2022 08:27:50 -0800 [thread overview]
Message-ID: <202212080827.41F083F@keescook> (raw)
In-Reply-To: <20221207154939.2532830-5-jeffxu@google.com>
On Wed, Dec 07, 2022 at 03:49:37PM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@google.com>
>
> In order to avoid WX mappings, add F_SEAL_WRITE when apply
> F_SEAL_EXEC to an executable memfd, so W^X from start.
>
> This implys application need to fill the content of the memfd first,
> after F_SEAL_EXEC is applied, application can no longer modify the
> content of the memfd.
>
> Typically, application seals the memfd right after writing to it.
> For example:
> 1. memfd_create(MFD_EXEC).
> 2. write() code to the memfd.
> 3. fcntl(F_ADD_SEALS, F_SEAL_EXEC) to convert the memfd to W^X.
> 4. call exec() on the memfd.
>
> Signed-off-by: Jeff Xu <jeffxu@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2022-12-08 16:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20221207154939.2532830-1-jeffxu@google.com>
2022-12-08 16:13 ` [PATCH v6 0/6] mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC Kees Cook
2022-12-08 18:33 ` Jeff Xu
2022-12-08 20:55 ` Kees Cook
[not found] ` <20221207154939.2532830-2-jeffxu@google.com>
2022-12-08 16:16 ` [PATCH v6 1/6] mm/memfd: add F_SEAL_EXEC Kees Cook
[not found] ` <20221207154939.2532830-3-jeffxu@google.com>
2022-12-08 16:21 ` [PATCH v6 2/6] selftests/memfd: add tests for F_SEAL_EXEC Kees Cook
[not found] ` <20221207154939.2532830-4-jeffxu@google.com>
2022-12-08 16:27 ` [PATCH v6 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC Kees Cook
2022-12-08 22:55 ` Jeff Xu
2022-12-16 15:46 ` Peter Xu
2022-12-16 17:15 ` Jeff Xu
2022-12-16 17:42 ` Andrew Morton
2022-12-16 18:11 ` Jeff Xu
2022-12-16 20:35 ` Kees Cook
2022-12-16 21:46 ` Jeff Xu
2022-12-16 22:06 ` Andrew Morton
2022-12-16 23:40 ` Jeff Xu
2022-12-20 16:55 ` Shuah Khan
2022-12-23 18:06 ` Jeff Xu
[not found] ` <20221207154939.2532830-5-jeffxu@google.com>
2022-12-08 16:27 ` Kees Cook [this message]
[not found] ` <20221207154939.2532830-6-jeffxu@google.com>
2022-12-08 16:30 ` [PATCH v6 5/6] selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC Kees Cook
[not found] ` <20221207154939.2532830-7-jeffxu@google.com>
2022-12-08 16:32 ` [PATCH v6 6/6] mm/memfd: security hook for memfd_create Kees Cook
2022-12-08 16:46 ` Kees Cook
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