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,
linux-security-module@vger.kernel.org,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v7 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC
Date: Wed, 14 Dec 2022 10:53:19 -0800 [thread overview]
Message-ID: <202212141053.DD016F79B@keescook> (raw)
In-Reply-To: <20221209160453.3246150-4-jeffxu@google.com>
On Fri, Dec 09, 2022 at 04:04:50PM +0000, jeffxu@chromium.org wrote:
> From: Jeff Xu <jeffxu@google.com>
>
> The new MFD_NOEXEC_SEAL and MFD_EXEC flags allows application to
> set executable bit at creation time (memfd_create).
>
> When MFD_NOEXEC_SEAL is set, memfd is created without executable bit
> (mode:0666), and sealed with F_SEAL_EXEC, so it can't be chmod to
> be executable (mode: 0777) after creation.
>
> when MFD_EXEC flag is set, memfd is created with executable bit
> (mode:0777), this is the same as the old behavior of memfd_create.
>
> The new pid namespaced sysctl vm.memfd_noexec has 3 values:
> 0: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> MFD_EXEC was set.
> 1: memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL acts like
> MFD_NOEXEC_SEAL was set.
> 2: memfd_create() without MFD_NOEXEC_SEAL will be rejected.
>
> The sysctl allows finer control of memfd_create for old-software
> that doesn't set the executable bit, for example, a container with
> vm.memfd_noexec=1 means the old-software will create non-executable
> memfd by default. Also, the value of memfd_noexec is passed to child
> namespace at creation time. For example, if the init namespace has
> vm.memfd_noexec=2, all its children namespaces will be created with 2.
>
> Signed-off-by: Jeff Xu <jeffxu@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2022-12-14 18:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-09 16:04 [PATCH v7 0/6] mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC jeffxu
2022-12-09 16:04 ` [PATCH v7 1/6] mm/memfd: add F_SEAL_EXEC jeffxu
2022-12-09 16:04 ` [PATCH v7 2/6] selftests/memfd: add tests for F_SEAL_EXEC jeffxu
2022-12-14 18:52 ` Kees Cook
2022-12-09 16:04 ` [PATCH v7 3/6] mm/memfd: add MFD_NOEXEC_SEAL and MFD_EXEC jeffxu
2022-12-14 18:53 ` Kees Cook [this message]
2022-12-16 18:39 ` SeongJae Park
2022-12-16 19:03 ` Jeff Xu
2022-12-16 19:21 ` Andrew Morton
2022-12-16 19:31 ` SeongJae Park
2022-12-09 16:04 ` [PATCH v7 4/6] mm/memfd: Add write seals when apply SEAL_EXEC to executable memfd jeffxu
2022-12-09 16:04 ` [PATCH v7 5/6] selftests/memfd: add tests for MFD_NOEXEC_SEAL MFD_EXEC jeffxu
2022-12-09 16:04 ` [PATCH v7 6/6] mm/memfd: security hook for memfd_create jeffxu
2022-12-09 17:02 ` Casey Schaufler
2022-12-09 18:29 ` Paul Moore
2022-12-13 15:00 ` Jeff Xu
2022-12-13 15:37 ` Casey Schaufler
2022-12-13 19:22 ` Paul Moore
2022-12-13 23:05 ` Jeff Xu
2025-09-20 5:54 ` Abhinav Saxena
2025-09-20 18:58 ` Jeff Xu
2022-12-09 18:15 ` [PATCH v7 0/6] mm/memfd: introduce MFD_NOEXEC_SEAL and MFD_EXEC Paul Moore
2022-12-14 18:54 ` Kees Cook
2022-12-14 23:32 ` Jeff Xu
2022-12-15 0:08 ` Kees Cook
2022-12-15 16:55 ` Jeff Xu
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