From: Florent Revest <revest@chromium.org>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: akpm@linux-foundation.org, catalin.marinas@arm.com,
anshuman.khandual@arm.com, joey.gouly@arm.com, mhocko@suse.com,
keescook@chromium.org, david@redhat.com, peterx@redhat.com,
izbyshev@ispras.ru, broonie@kernel.org, szabolcs.nagy@arm.com,
kpsingh@kernel.org, gthelen@google.com, toiwoton@gmail.com,
ayush.jain3@amd.com, Florent Revest <revest@chromium.org>
Subject: [PATCH v4 0/6] MDWE without inheritance
Date: Mon, 28 Aug 2023 17:08:52 +0200 [thread overview]
Message-ID: <20230828150858.393570-1-revest@chromium.org> (raw)
Joey recently introduced a Memory-Deny-Write-Executable (MDWE) prctl which tags
current with a flag that prevents pages that were previously not executable from
becoming executable.
This tag always gets inherited by children tasks. (it's in MMF_INIT_MASK)
At Google, we've been using a somewhat similar downstream patch for a few years
now. To make the adoption of this feature easier, we've had it support a mode in
which the W^X flag does not propagate to children. For example, this is handy if
a C process which wants W^X protection suspects it could start children
processes that would use a JIT.
I'd like to align our features with the upstream prctl. This series proposes a
new NO_INHERIT flag to the MDWE prctl to make this kind of adoption easier. It
sets a different flag in current that is not in MMF_INIT_MASK and which does not
propagate.
As part of looking into MDWE, I also fixed a couple of things in the MDWE test.
This series applies on the mm-everything-2023-08-25-20-06 tag of the mm tree:
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/
Diff since v3:
- Added a bunch of Reviewed-by, Acked-by and Tested-by. Thanks everyone!
- Reworded patch 2's description for clarity
- Removed an unnecessary int cast
- Added test coverage for errnos of invalid prctls (EPERM/EINVAL)
- Added test coverage for can_keep_no_flags and can_keep_both_flags
Diff since v2:
- Turned the MMF_INIT_FLAGS macro into a mmf_init_flags function as suggested by
David Hildenbrand
- Removed the ability to transition from to PR_MDWE_REFUSE_EXEC_GAIN from
(PR_MDWE_REFUSE_EXEC_GAIN | PR_MDWE_NO_INHERIT) which also significantly
simplifies the prctl_set_mdwe logic
- Cc-ed -stable on patch 3 as suggested by Alexey Izbyshev
- Added a handful of Reviewed-by/Acked-by trailers
Diff since v1:
- MMF_HAS_MDWE_NO_INHERIT clears MMF_HAS_MDWE in the fork path as part of a
MMF_INIT_FLAGS macro (suggested by Catalin)
- PR_MDWE_* are defined as unsigned long rather than int (suggested by Andrey)
Florent Revest (6):
kselftest: vm: Fix tabs/spaces inconsistency in the mdwe test
kselftest: vm: Fix mdwe's mmap_FIXED test case
kselftest: vm: Check errnos in mdwe_test
mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned long
mm: Add a NO_INHERIT flag to the PR_SET_MDWE prctl
kselftest: vm: Add tests for no-inherit memory-deny-write-execute
include/linux/sched/coredump.h | 10 ++
include/uapi/linux/prctl.h | 3 +-
kernel/fork.c | 2 +-
kernel/sys.c | 32 ++++--
tools/include/uapi/linux/prctl.h | 3 +-
tools/testing/selftests/mm/mdwe_test.c | 137 ++++++++++++++++++++++---
6 files changed, 163 insertions(+), 24 deletions(-)
--
2.42.0.rc2.253.gd59a3bf2b4-goog
next reply other threads:[~2023-08-28 15:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-28 15:08 Florent Revest [this message]
2023-08-28 15:08 ` [PATCH v4 1/6] kselftest: vm: Fix tabs/spaces inconsistency in the mdwe test Florent Revest
2023-08-28 15:08 ` [PATCH v4 2/6] kselftest: vm: Fix mdwe's mmap_FIXED test case Florent Revest
2023-08-28 15:08 ` [PATCH v4 3/6] kselftest: vm: Check errnos in mdwe_test Florent Revest
2023-08-28 18:45 ` Kees Cook
2023-09-21 9:51 ` Catalin Marinas
2023-08-28 15:08 ` [PATCH v4 4/6] mm: Make PR_MDWE_REFUSE_EXEC_GAIN an unsigned long Florent Revest
2023-09-22 1:29 ` Andrew Morton
2023-09-22 13:10 ` Florent Revest
2023-08-28 15:08 ` [PATCH v4 5/6] mm: Add a NO_INHERIT flag to the PR_SET_MDWE prctl Florent Revest
2023-09-22 1:33 ` Andrew Morton
2023-10-03 15:52 ` Florent Revest
2023-08-28 15:08 ` [PATCH v4 6/6] kselftest: vm: Add tests for no-inherit memory-deny-write-execute Florent Revest
2023-08-28 18:45 ` Kees Cook
2023-09-20 19:56 ` [PATCH v4 0/6] MDWE without inheritance Florent Revest
2023-09-21 9:52 ` Catalin Marinas
2023-09-21 9:57 ` Florent Revest
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