From patchwork Mon Nov 20 23:54:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 745916 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D47813B2B7; Mon, 20 Nov 2023 23:55:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kXPWNcG5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 117A9C433CD; Mon, 20 Nov 2023 23:55:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1700524557; bh=owctnHEQpTZFQ/Gh7J9JCdoUfmKHACZs61x8UVn64fA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=kXPWNcG58IzRJcCMYKqGURnJUj6rneGHKU5SHp+Yf638TdXxD6qdEjDB7S6BCsaPN kw1grYPFTeK8O5cG4h2X1cqzvy7XNsobjqD1iKKOpu1y7GW7ir3IcILs1wvsxePXiX Om32bgn+r0Kc4xsb7B1qJWMcY1ZTdpkCqgZG6axe8UqYiPPUaoeS9aNspPLDfQYe7F 4i5WaIbb0Lb48acRfEomtvfTLDEae9OiDs96AATwQ4MzV7kPJ53TypjDlyYATRcP1F nhlKAg5hr5a2EkdbbJmjlz8SdWFaQ9QHXR6en4tnnzhDUYXYcnIjzDOwk8LfxvxLFB a0M4ISsRfNyLg== From: Mark Brown Date: Mon, 20 Nov 2023 23:54:33 +0000 Subject: [PATCH RFT v3 5/5] kselftest/clone3: Test shadow stack support Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231120-clone3-shadow-stack-v3-5-a7b8ed3e2acc@kernel.org> References: <20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@kernel.org> In-Reply-To: <20231120-clone3-shadow-stack-v3-0-a7b8ed3e2acc@kernel.org> To: "Rick P. Edgecombe" , Deepak Gupta , Szabolcs Nagy , "H.J. Lu" , Florian Weimer , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Christian Brauner , Shuah Khan Cc: linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Kees Cook , jannh@google.com, bsegall@google.com, linux-kselftest@vger.kernel.org, linux-api@vger.kernel.org, Mark Brown X-Mailer: b4 0.13-dev-0438c X-Developer-Signature: v=1; a=openpgp-sha256; l=6256; i=broonie@kernel.org; h=from:subject:message-id; bh=owctnHEQpTZFQ/Gh7J9JCdoUfmKHACZs61x8UVn64fA=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBlW/HiMlAIrIk0zoNZPXS7mjGALNqlLtxI2zW1lzFx 3jMYT1aJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZVvx4gAKCRAk1otyXVSH0ET0B/ 4nvEdmzpCcydJg0+47Rl9429nQXE80i9vOlZZ/9WqqOIYAlKpHeFSIOp/PZDC83mbAQAxnUgbUKz02 SCY9ehwt0jFjCW6KAfX3s5hXXl5tcbhUGCHr9lyXvKF4RC8gUhqsAn7Di0fIfaEyPir7UEEbwfAI9N KAD4OkZsq2rJBXu/VfcqDkUqE3NAI/WfYWh0ztHPuhz7F+6+z34EL5+xqEN+LBsYQMbB/5dVN/Icjx XRa8eunc+ibLyI5fUpjAe8aUnbiQwU+xUl/9w21ilfDLimj8hwbZSMx5zyvOvN2sl31yjPqo6wtKaB Qpc9fjLP8sGNv3P8Guq8Q/ZS7Ha8T6 X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Add basic test coverage for specifying the shadow stack for a newly created thread via clone3(), including coverage of the newly extended argument structure. In order to facilitate testing on systems without userspace shadow stack support we manually enable shadow stacks on startup, this is architecture specific due to the use of an arch_prctl() on x86. Due to interactions with potential userspace locking of features we actually detect support for shadow stacks on the running system by attempting to allocate a shadow stack page during initialisation using map_shadow_stack(), warning if this succeeds when the enable failed. Signed-off-by: Mark Brown --- tools/testing/selftests/clone3/clone3.c | 117 ++++++++++++++++++++++ tools/testing/selftests/clone3/clone3_selftests.h | 7 ++ 2 files changed, 124 insertions(+) diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c index 6adbfd14c841..0f9f99dc5aac 100644 --- a/tools/testing/selftests/clone3/clone3.c +++ b/tools/testing/selftests/clone3/clone3.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -21,6 +22,10 @@ #include "../kselftest.h" #include "clone3_selftests.h" +static bool shadow_stack_enabled; +static bool shadow_stack_supported; +static size_t max_supported_args_size; + enum test_mode { CLONE3_ARGS_NO_TEST, CLONE3_ARGS_ALL_0, @@ -28,6 +33,7 @@ enum test_mode { CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG, CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG, CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG, + CLONE3_ARGS_SHADOW_STACK, }; typedef bool (*filter_function)(void); @@ -44,6 +50,36 @@ struct test { filter_function filter; }; +#ifndef __NR_map_shadow_stack +#define __NR_map_shadow_stack 453 +#endif + +/* + * We check for shadow stack support by attempting to use + * map_shadow_stack() since features may have been locked by the + * dynamic linker resulting in spurious errors when we attempt to + * enable on startup. We warn if the enable failed. + */ +static void test_shadow_stack_supported(void) +{ + long shadow_stack; + + shadow_stack = syscall(__NR_map_shadow_stack, 0, getpagesize(), 0); + if (shadow_stack == -1) { + ksft_print_msg("map_shadow_stack() not supported\n"); + } else if ((void *)shadow_stack == MAP_FAILED) { + ksft_print_msg("Failed to map shadow stack\n"); + } else { + ksft_print_msg("Shadow stack supportd\n"); + shadow_stack_supported = true; + + if (!shadow_stack_enabled) + ksft_print_msg("Mapped but did not enable shadow stack\n"); + + munmap((void *)shadow_stack, getpagesize()); + } +} + static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) { struct __clone_args args = { @@ -89,6 +125,9 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG: args.exit_signal = 0x00000000000000f0ULL; break; + case CLONE3_ARGS_SHADOW_STACK: + args.shadow_stack_size = getpagesize(); + break; } memcpy(&args_ext.args, &args, sizeof(struct __clone_args)); @@ -179,6 +218,26 @@ static bool no_timenamespace(void) return true; } +static bool have_shadow_stack(void) +{ + if (shadow_stack_supported) { + ksft_print_msg("Shadow stack supported\n"); + return true; + } + + return false; +} + +static bool no_shadow_stack(void) +{ + if (!shadow_stack_supported) { + ksft_print_msg("Shadow stack not supported\n"); + return true; + } + + return false; +} + static size_t page_size_plus_8(void) { return getpagesize() + 8; @@ -322,16 +381,74 @@ static const struct test tests[] = { .expected = -EINVAL, .test_mode = CLONE3_ARGS_NO_TEST, }, + { + .name = "Shadow stack on system with shadow stack", + .flags = CLONE_VM, + .size = 0, + .expected = 0, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK, + .filter = no_shadow_stack, + }, + { + .name = "Shadow stack on system without shadow stack", + .flags = CLONE_VM, + .size = 0, + .expected = -EINVAL, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK, + .filter = have_shadow_stack, + }, }; +#ifdef __x86_64__ +#define ARCH_SHSTK_ENABLE 0x5001 +#define ARCH_SHSTK_SHSTK (1ULL << 0) + +#define ARCH_PRCTL(arg1, arg2) \ +({ \ + long _ret; \ + register long _num asm("eax") = __NR_arch_prctl; \ + register long _arg1 asm("rdi") = (long)(arg1); \ + register long _arg2 asm("rsi") = (long)(arg2); \ + \ + asm volatile ( \ + "syscall\n" \ + : "=a"(_ret) \ + : "r"(_arg1), "r"(_arg2), \ + "0"(_num) \ + : "rcx", "r11", "memory", "cc" \ + ); \ + _ret; \ +}) + +#define ENABLED_SHADOW_STACK +static inline void enable_shadow_stack(void) +{ + int ret = ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_SHSTK); + if (ret == 0) + shadow_stack_enabled = true; +} + +#endif + +#ifndef ENABLE_SHADOW_STACK +static void enable_shadow_stack(void) +{ +} +#endif + int main(int argc, char *argv[]) { size_t size; int i; + enable_shadow_stack(); + ksft_print_header(); ksft_set_plan(ARRAY_SIZE(tests)); test_clone3_supported(); + test_shadow_stack_supported(); for (i = 0; i < ARRAY_SIZE(tests); i++) test_clone3(&tests[i]); diff --git a/tools/testing/selftests/clone3/clone3_selftests.h b/tools/testing/selftests/clone3/clone3_selftests.h index 3d2663fe50ba..2e06127091f5 100644 --- a/tools/testing/selftests/clone3/clone3_selftests.h +++ b/tools/testing/selftests/clone3/clone3_selftests.h @@ -31,6 +31,13 @@ struct __clone_args { __aligned_u64 set_tid; __aligned_u64 set_tid_size; __aligned_u64 cgroup; +#ifndef CLONE_ARGS_SIZE_VER2 +#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */ +#endif + __aligned_u64 shadow_stack_size; +#ifndef CLONE_ARGS_SIZE_VER3 +#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */ +#endif }; static pid_t sys_clone3(struct __clone_args *args, size_t size)