The kernel has recently added support for shadow stacks, currently
x86 only using their CET feature but both arm64 and RISC-V have
equivalent features (GCS and Zicfiss respectively), I am actively
working on GCS[1]. With shadow stacks the hardware maintains an
additional stack containing only the return addresses for branch
instructions which is not generally writeable by userspace and ensures
that any returns are to the recorded addresses. This provides some
protection against ROP attacks and making it easier to collect call
stacks. These shadow stacks are allocated in the address space of the
userspace process.
Our API for shadow stacks does not currently offer userspace any
flexiblity for managing the allocation of shadow stacks for newly
created threads, instead the kernel allocates a new shadow stack with
the same size as the normal stack whenever a thread is created with the
feature enabled. The stacks allocated in this way are freed by the
kernel when the thread exits or shadow stacks are disabled for the
thread. This lack of flexibility and control isn't ideal, in the vast
majority of cases the shadow stack will be over allocated and the
implicit allocation and deallocation is not consistent with other
interfaces. As far as I can tell the interface is done in this manner
mainly because the shadow stack patches were in development since before
clone3() was implemented.
Since clone3() is readily extensible let's add support for specifying a
shadow stack when creating a new thread or process in a similar manner
to how the normal stack is specified, keeping the current implicit
allocation behaviour if one is not specified either with clone3() or
through the use of clone(). The user must provide a shadow stack
address and size, this must point to memory mapped for use as a shadow
stackby map_shadow_stack() with a shadow stack token at the top of the
stack.
Please note that the x86 portions of this code are build tested only, I
don't appear to have a system that can run CET avaible to me, I have
done testing with an integration into my pending work for GCS. There is
some possibility that the arm64 implementation may require the use of
clone3() and explicit userspace allocation of shadow stacks, this is
still under discussion.
Please further note that the token consumption done by clone3() is not
currently implemented in an atomic fashion, Rick indicated that he would
look into fixing this if people are OK with the implementation.
A new architecture feature Kconfig option for shadow stacks is added as
here, this was suggested as part of the review comments for the arm64
GCS series and since we need to detect if shadow stacks are supported it
seemed sensible to roll it in here.
[1] https://lore.kernel.org/r/20231009-arm64-gcs-v6-0-78e55deaa4dd@kernel.org/
Signed-off-by: Mark Brown <broonie(a)kernel.org>
---
Changes in v9:
- Pull token validation earlier and report problems with an error return
to parent rather than signal delivery to the child.
- Verify that the top of the supplied shadow stack is VM_SHADOW_STACK.
- Rework token validation to only do the page mapping once.
- Drop no longer needed support for testing for signals in selftest.
- Fix typo in comments.
- Link to v8: https://lore.kernel.org/r/20240808-clone3-shadow-stack-v8-0-0acf37caf14c@ke…
Changes in v8:
- Fix token verification with user specified shadow stack.
- Don't track user managed shadow stacks for child processes.
- Link to v7: https://lore.kernel.org/r/20240731-clone3-shadow-stack-v7-0-a9532eebfb1d@ke…
Changes in v7:
- Rebase onto v6.11-rc1.
- Typo fixes.
- Link to v6: https://lore.kernel.org/r/20240623-clone3-shadow-stack-v6-0-9ee7783b1fb9@ke…
Changes in v6:
- Rebase onto v6.10-rc3.
- Ensure we don't try to free the parent shadow stack in error paths of
x86 arch code.
- Spelling fixes in userspace API document.
- Additional cleanups and improvements to the clone3() tests to support
the shadow stack tests.
- Link to v5: https://lore.kernel.org/r/20240203-clone3-shadow-stack-v5-0-322c69598e4b@ke…
Changes in v5:
- Rebase onto v6.8-rc2.
- Rework ABI to have the user allocate the shadow stack memory with
map_shadow_stack() and a token.
- Force inlining of the x86 shadow stack enablement.
- Move shadow stack enablement out into a shared header for reuse by
other tests.
- Link to v4: https://lore.kernel.org/r/20231128-clone3-shadow-stack-v4-0-8b28ffe4f676@ke…
Changes in v4:
- Formatting changes.
- Use a define for minimum shadow stack size and move some basic
validation to fork.c.
- Link to v3: https://lore.kernel.org/r/20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@ke…
Changes in v3:
- Rebase onto v6.7-rc2.
- Remove stale shadow_stack in internal kargs.
- If a shadow stack is specified unconditionally use it regardless of
CLONE_ parameters.
- Force enable shadow stacks in the selftest.
- Update changelogs for RISC-V feature rename.
- Link to v2: https://lore.kernel.org/r/20231114-clone3-shadow-stack-v2-0-b613f8681155@ke…
Changes in v2:
- Rebase onto v6.7-rc1.
- Remove ability to provide preallocated shadow stack, just specify the
desired size.
- Link to v1: https://lore.kernel.org/r/20231023-clone3-shadow-stack-v1-0-d867d0b5d4d0@ke…
---
Mark Brown (8):
Documentation: userspace-api: Add shadow stack API documentation
selftests: Provide helper header for shadow stack testing
mm: Introduce ARCH_HAS_USER_SHADOW_STACK
fork: Add shadow stack support to clone3()
selftests/clone3: Remove redundant flushes of output streams
selftests/clone3: Factor more of main loop into test_clone3()
selftests/clone3: Allow tests to flag if -E2BIG is a valid error code
selftests/clone3: Test shadow stack support
Documentation/userspace-api/index.rst | 1 +
Documentation/userspace-api/shadow_stack.rst | 41 ++++
arch/x86/Kconfig | 1 +
arch/x86/include/asm/shstk.h | 11 +-
arch/x86/kernel/process.c | 2 +-
arch/x86/kernel/shstk.c | 103 +++++++---
fs/proc/task_mmu.c | 2 +-
include/linux/mm.h | 2 +-
include/linux/sched/task.h | 18 ++
include/uapi/linux/sched.h | 13 +-
kernel/fork.c | 114 +++++++++--
mm/Kconfig | 6 +
tools/testing/selftests/clone3/clone3.c | 230 ++++++++++++++++++----
tools/testing/selftests/clone3/clone3_selftests.h | 40 +++-
tools/testing/selftests/ksft_shstk.h | 63 ++++++
15 files changed, 560 insertions(+), 87 deletions(-)
---
base-commit: 8400291e289ee6b2bf9779ff1c83a291501f017b
change-id: 20231019-clone3-shadow-stack-15d40d2bf536
Best regards,
--
Mark Brown <broonie(a)kernel.org>
Hi all,
This is part of a hackathon organized by LKCAMP[1], focused on writing
tests using KUnit. We reached out a while ago asking for advice on what
would be a useful contribution[2] and ended up choosing data structures
that did not yet have tests.
This patch adds tests for the llist data structure, defined in
include/linux/llist.h, and is inspired by the KUnit tests for the doubly
linked list in lib/list-test.c[3].
It is important to note that this patch depends on the patch referenced
in [4], as it utilizes the newly created lib/tests/ subdirectory.
[1] https://lkcamp.dev/about/
[2] https://lore.kernel.org/all/Zktnt7rjKryTh9-N@arch/
[3] https://elixir.bootlin.com/linux/latest/source/lib/list-test.c
[4] https://lore.kernel.org/all/20240720181025.work.002-kees@kernel.org/
---
Changes in v3:
- Resolved checkpatch warnings:
- Renamed tests for macros starting with 'for_each'
- Removed link from commit message
- Replaced hardcoded constants with ENTRIES_SIZE
- Updated initialization of llist_node array
- Fixed typos
- Update Kconfig.debug message for llist_kunit
Changes in v2:
- Add MODULE_DESCRIPTION()
- Move the tests from lib/llist_kunit.c to lib/tests/llist_kunit.c
- Change the license from "GPL v2" to "GPL"
Artur Alves (1):
lib/llist_kunit.c: add KUnit tests for llist
lib/Kconfig.debug | 11 ++
lib/tests/Makefile | 1 +
lib/tests/llist_kunit.c | 358 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 370 insertions(+)
create mode 100644 lib/tests/llist_kunit.c
--
2.46.0
The SLUB changes for 6.12 included new kunit tests that resulted in
noisy warnings, which we normally suppress, and a boot lockup in some
configurations in case the kunit tests are built-in.
The warnings are addressed in Patch 1.
The lockups I couldn't reproduce, but inspecting boot initialization
order makes me suspect the tests (which call few RCU operations) are
being executed a bit too early before RCU finishes initialization.
Moving the exection later seems to do the trick, so I'd like to ask
kunit folks to ack this change (Patch 2). If RCU folks have any
insights, it would be welcome too.
So these are now fixes for 4e1c44b3db79 ("kunit, slub: add
test_kfree_rcu() and test_leak_destroy()")
Once sent as a full patch, I also want to include comment fixes from
Ulad for kvfree_rcu_queue_batch():
https://lore.kernel.org/all/CA%2BKHdyV%3D0dpJX_v_tcuTQ-_ree-Yb9ch3F_HqfT4Yn…
The plan is to take the fixes via slab tree for a 6.12 rcX.
Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz>
---
Vlastimil Babka (2):
mm, slab: suppress warnings in test_leak_destroy kunit test
kunit: move call to kunit_run_all_tests() after rcu_end_inkernel_boot()
init/main.c | 4 ++--
lib/slub_kunit.c | 4 ++--
mm/slab.h | 6 ++++++
mm/slab_common.c | 5 +++--
mm/slub.c | 5 +++--
5 files changed, 16 insertions(+), 8 deletions(-)
---
base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
change-id: 20240930-b4-slub-kunit-fix-6fba4d1c1742
Best regards,
--
Vlastimil Babka <vbabka(a)suse.cz>
rxq contains a pointer to the device from where
the redirect happened. Currently, the BPF program
that was executed after a redirect via BPF_MAP_TYPE_DEVMAP*
does not have it set.
Add bugfix and related selftest.
Signed-off-by: Florian Kauer <florian.kauer(a)linutronix.de>
---
Changes in v4:
- return -> goto out_close, thanks Toke
- Link to v3: https://lore.kernel.org/r/20240909-devel-koalo-fix-ingress-ifindex-v3-0-662…
Changes in v3:
- initialize skel to NULL, thanks Stanislav
- Link to v2: https://lore.kernel.org/r/20240906-devel-koalo-fix-ingress-ifindex-v2-0-4ca…
Changes in v2:
- changed fixes tag
- added selftest
- Link to v1: https://lore.kernel.org/r/20240905-devel-koalo-fix-ingress-ifindex-v1-1-d12…
---
Florian Kauer (2):
bpf: devmap: provide rxq after redirect
bpf: selftests: send packet to devmap redirect XDP
kernel/bpf/devmap.c | 11 +-
.../selftests/bpf/prog_tests/xdp_devmap_attach.c | 114 +++++++++++++++++++--
2 files changed, 115 insertions(+), 10 deletions(-)
---
base-commit: 8e69c96df771ab469cec278edb47009351de4da6
change-id: 20240905-devel-koalo-fix-ingress-ifindex-b9293d471db6
Best regards,
--
Florian Kauer <florian.kauer(a)linutronix.de>
step_after_suspend_test fails with device busy error while
writing to /sys/power/state to start suspend. The test believes
it failed to enter suspend state with
$ sudo ./step_after_suspend_test
TAP version 13
Bail out! Failed to enter Suspend state
However, in the kernel message, I indeed see the system get
suspended and then wake up later.
[611172.033108] PM: suspend entry (s2idle)
[611172.044940] Filesystems sync: 0.006 seconds
[611172.052254] Freezing user space processes
[611172.059319] Freezing user space processes completed (elapsed 0.001 seconds)
[611172.067920] OOM killer disabled.
[611172.072465] Freezing remaining freezable tasks
[611172.080332] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[611172.089724] printk: Suspending console(s) (use no_console_suspend to debug)
[611172.117126] serial 00:03: disabled
some other hardware get reconnected
[611203.136277] OOM killer enabled.
[611203.140637] Restarting tasks ...
[611203.141135] usb 1-8.1: USB disconnect, device number 7
[611203.141755] done.
[611203.155268] random: crng reseeded on system resumption
[611203.162059] PM: suspend exit
After investigation, I noticed that for the code block
if (write(power_state_fd, "mem", strlen("mem")) != strlen("mem"))
ksft_exit_fail_msg("Failed to enter Suspend state\n");
The write will return -1 and errno is set to 16 (device busy).
It should be caused by the write function is not successfully returned
before the system suspend and the return value get messed when waking up.
As a result, It may be better to check the time passed of those few
instructions to determine whether the suspend is executed correctly for
it is pretty hard to execute those few lines for 5 seconds.
The timer to wake up the system is set to expire after 5 seconds and
no re-arm. If the timer remaining time is 0 second and 0 nano secomd,
it means the timer expired and wake the system up. Otherwise, the system
could be considered to enter the suspend state failed if there is any
remaining time.
After appling this patch, the test would not fail for it believes the
system does not go to suspend by mistake. It now could continue to the
rest part of the test after suspend.
Fixes: bfd092b8c272 ("selftests: breakpoint: add step_after_suspend_test")
Reported-by: Sinadin Shan <sinadin.shan(a)oracle.com>
Signed-off-by: Yifei Liu <yifei.l.liu(a)oracle.com>
---
v4->v5: Remove the above quotes in the first part.
remove the incorrect format which could confuse the git.
---
.../testing/selftests/breakpoints/step_after_suspend_test.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/breakpoints/step_after_suspend_test.c b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
index dfec31fb9b30d..8d275f03e977f 100644
--- a/tools/testing/selftests/breakpoints/step_after_suspend_test.c
+++ b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
@@ -152,7 +152,10 @@ void suspend(void)
if (err < 0)
ksft_exit_fail_msg("timerfd_settime() failed\n");
- if (write(power_state_fd, "mem", strlen("mem")) != strlen("mem"))
+ system("(echo mem > /sys/power/state) 2> /dev/null");
+
+ timerfd_gettime(timerfd, &spec);
+ if (spec.it_value.tv_sec != 0 || spec.it_value.tv_nsec != 0)
ksft_exit_fail_msg("Failed to enter Suspend state\n");
close(timerfd);
--
2.46.0