lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20241001-arm64-gcs-v13-36-222b78d87eee@kernel.org>
Date: Tue, 01 Oct 2024 23:59:15 +0100
From: Mark Brown <broonie@...nel.org>
To: Catalin Marinas <catalin.marinas@....com>, 
 Will Deacon <will@...nel.org>, Jonathan Corbet <corbet@....net>, 
 Andrew Morton <akpm@...ux-foundation.org>, Marc Zyngier <maz@...nel.org>, 
 Oliver Upton <oliver.upton@...ux.dev>, James Morse <james.morse@....com>, 
 Suzuki K Poulose <suzuki.poulose@....com>, Arnd Bergmann <arnd@...db.de>, 
 Oleg Nesterov <oleg@...hat.com>, Eric Biederman <ebiederm@...ssion.com>, 
 Shuah Khan <shuah@...nel.org>, 
 "Rick P. Edgecombe" <rick.p.edgecombe@...el.com>, 
 Deepak Gupta <debug@...osinc.com>, Ard Biesheuvel <ardb@...nel.org>, 
 Szabolcs Nagy <Szabolcs.Nagy@....com>, Kees Cook <kees@...nel.org>
Cc: "H.J. Lu" <hjl.tools@...il.com>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Florian Weimer <fweimer@...hat.com>, Christian Brauner <brauner@...nel.org>, 
 Thiago Jung Bauermann <thiago.bauermann@...aro.org>, 
 Ross Burton <ross.burton@....com>, David Spickett <david.spickett@....com>, 
 Yury Khrustalev <yury.khrustalev@....com>, 
 Wilco Dijkstra <wilco.dijkstra@....com>, 
 linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org, 
 kvmarm@...ts.linux.dev, linux-fsdevel@...r.kernel.org, 
 linux-arch@...r.kernel.org, linux-mm@...ck.org, 
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-riscv@...ts.infradead.org, Mark Brown <broonie@...nel.org>
Subject: [PATCH v13 36/40] kselftest/arm64: Add test coverage for GCS mode
 locking

Verify that we can lock individual GCS mode bits, that other modes
aren't affected and as a side effect also that every combination of
modes can be enabled.

Normally the inability to reenable GCS after disabling it would be an
issue with testing but fortunately the kselftest_harness runs each test
within a fork()ed child.  This can be inconvenient for some kinds of
testing but here it means that each test is in a separate thread and
therefore won't be affected by other tests in the suite.

Once we get toolchains with support for enabling GCS by default we will
need to take care to not do that in the build system but there are no
such toolchains yet so it is not yet an issue.

Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@...aro.org>
Tested-by: Thiago Jung Bauermann <thiago.bauermann@...aro.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 tools/testing/selftests/arm64/gcs/.gitignore    |   1 +
 tools/testing/selftests/arm64/gcs/Makefile      |   2 +-
 tools/testing/selftests/arm64/gcs/gcs-locking.c | 200 ++++++++++++++++++++++++
 3 files changed, 202 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/arm64/gcs/.gitignore b/tools/testing/selftests/arm64/gcs/.gitignore
index 5810c4a163d4..0c86f53f68ad 100644
--- a/tools/testing/selftests/arm64/gcs/.gitignore
+++ b/tools/testing/selftests/arm64/gcs/.gitignore
@@ -1,2 +1,3 @@
 basic-gcs
 libc-gcs
+gcs-locking
diff --git a/tools/testing/selftests/arm64/gcs/Makefile b/tools/testing/selftests/arm64/gcs/Makefile
index a8fdf21e9a47..2173d6275956 100644
--- a/tools/testing/selftests/arm64/gcs/Makefile
+++ b/tools/testing/selftests/arm64/gcs/Makefile
@@ -6,7 +6,7 @@
 # nolibc.
 #
 
-TEST_GEN_PROGS := basic-gcs libc-gcs
+TEST_GEN_PROGS := basic-gcs libc-gcs gcs-locking
 
 LDLIBS+=-lpthread
 
diff --git a/tools/testing/selftests/arm64/gcs/gcs-locking.c b/tools/testing/selftests/arm64/gcs/gcs-locking.c
new file mode 100644
index 000000000000..989f75a491b7
--- /dev/null
+++ b/tools/testing/selftests/arm64/gcs/gcs-locking.c
@@ -0,0 +1,200 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 ARM Limited.
+ *
+ * Tests for GCS mode locking.  These tests rely on both having GCS
+ * unconfigured on entry and on the kselftest harness running each
+ * test in a fork()ed process which will have it's own mode.
+ */
+
+#include <limits.h>
+
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+
+#include <asm/hwcap.h>
+
+#include "kselftest_harness.h"
+
+#include "gcs-util.h"
+
+#define my_syscall2(num, arg1, arg2)                                          \
+({                                                                            \
+	register long _num  __asm__ ("x8") = (num);                           \
+	register long _arg1 __asm__ ("x0") = (long)(arg1);                    \
+	register long _arg2 __asm__ ("x1") = (long)(arg2);                    \
+	register long _arg3 __asm__ ("x2") = 0;                               \
+	register long _arg4 __asm__ ("x3") = 0;                               \
+	register long _arg5 __asm__ ("x4") = 0;                               \
+	                                                                      \
+	__asm__  volatile (                                                   \
+		"svc #0\n"                                                    \
+		: "=r"(_arg1)                                                 \
+		: "r"(_arg1), "r"(_arg2),                                     \
+		  "r"(_arg3), "r"(_arg4),                                     \
+		  "r"(_arg5), "r"(_num)					      \
+		: "memory", "cc"                                              \
+	);                                                                    \
+	_arg1;                                                                \
+})
+
+/* No mode bits are rejected for locking */
+TEST(lock_all_modes)
+{
+	int ret;
+
+	ret = prctl(PR_LOCK_SHADOW_STACK_STATUS, ULONG_MAX, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+}
+
+FIXTURE(valid_modes)
+{
+};
+
+FIXTURE_VARIANT(valid_modes)
+{
+	unsigned long mode;
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable)
+{
+	.mode = PR_SHADOW_STACK_ENABLE,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_write)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_push)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_PUSH,
+};
+
+FIXTURE_VARIANT_ADD(valid_modes, enable_write_push)
+{
+	.mode = PR_SHADOW_STACK_ENABLE | PR_SHADOW_STACK_WRITE |
+		PR_SHADOW_STACK_PUSH,
+};
+
+FIXTURE_SETUP(valid_modes)
+{
+}
+
+FIXTURE_TEARDOWN(valid_modes)
+{
+}
+
+/* We can set the mode at all */
+TEST_F(valid_modes, set)
+{
+	int ret;
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  variant->mode);
+	ASSERT_EQ(ret, 0);
+
+	_exit(0);
+}
+
+/* Enabling, locking then disabling is rejected */
+TEST_F(valid_modes, enable_lock_disable)
+{
+	unsigned long mode;
+	int ret;
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  variant->mode);
+	ASSERT_EQ(ret, 0);
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(mode, variant->mode);
+
+	ret = prctl(PR_LOCK_SHADOW_STACK_STATUS, variant->mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, 0);
+	ASSERT_EQ(ret, -EBUSY);
+
+	_exit(0);
+}
+
+/* Locking then enabling is rejected */
+TEST_F(valid_modes, lock_enable)
+{
+	unsigned long mode;
+	int ret;
+
+	ret = prctl(PR_LOCK_SHADOW_STACK_STATUS, variant->mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  variant->mode);
+	ASSERT_EQ(ret, -EBUSY);
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(mode, 0);
+
+	_exit(0);
+}
+
+/* Locking then changing other modes is fine */
+TEST_F(valid_modes, lock_enable_disable_others)
+{
+	unsigned long mode;
+	int ret;
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  variant->mode);
+	ASSERT_EQ(ret, 0);
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(mode, variant->mode);
+
+	ret = prctl(PR_LOCK_SHADOW_STACK_STATUS, variant->mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  PR_SHADOW_STACK_ALL_MODES);
+	ASSERT_EQ(ret, 0);
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(mode, PR_SHADOW_STACK_ALL_MODES);
+
+
+	ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS,
+			  variant->mode);
+	ASSERT_EQ(ret, 0);
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	ASSERT_EQ(ret, 0);
+	ASSERT_EQ(mode, variant->mode);
+
+	_exit(0);
+}
+
+int main(int argc, char **argv)
+{
+	unsigned long mode;
+	int ret;
+
+	if (!(getauxval(AT_HWCAP) & HWCAP_GCS))
+		ksft_exit_skip("SKIP GCS not supported\n");
+
+	ret = prctl(PR_GET_SHADOW_STACK_STATUS, &mode, 0, 0, 0);
+	if (ret) {
+		ksft_print_msg("Failed to read GCS state: %d\n", ret);
+		return EXIT_FAILURE;
+	}
+
+	if (mode & PR_SHADOW_STACK_ENABLE) {
+		ksft_print_msg("GCS was enabled, test unsupported\n");
+		return KSFT_SKIP;
+	}
+
+	return test_harness_run(argc, argv);
+}

-- 
2.39.2


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ