From patchwork Tue Dec 3 18:43:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892810 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 53E9B1FDE14; Tue, 3 Dec 2024 18:44:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251454; cv=none; b=olYPqkTUh9lPs347unmgfW12aMNR1Z1YjQbEp2OG0K7H+g2tPebq65ulG7ODmbopHPsiUF339MUAzuwHnGE8c7PpY/If6o4+xvWmtgyP9/uGWau3Tv+iIbPoV4T4Ce9zcs9eQnE7fA1cik9MIXd/1j56xVGkrRdxbIhl2CSSpgU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251454; c=relaxed/simple; bh=ZPECVt2iZI6cgmwzVsOfP4QoLnc65CaYS1gJJRUNbtE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=SC2aAFtrpY2YKNaOoZFM7lf5fnteRMdjKdMg+9c0akpdvhN1fqG+GkEGoYkW1s7KkfSLqh71YRNXzTGCztUyE0s8PlhzkHvmPFB+e83kvxRf1dRo1msZl02MAFOsBrIw+kCD+mG9DUI/7CRbvuakdN8frK4Q3f/QsBmXCP4/pl0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Kx9/k09S; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Kx9/k09S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2850BC4CED9; Tue, 3 Dec 2024 18:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251453; bh=ZPECVt2iZI6cgmwzVsOfP4QoLnc65CaYS1gJJRUNbtE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Kx9/k09SidkndvuTVwbQU2b+cKaPjXyzNTWHrgaELxKPLjmy3UVnNq2Otby9FLsn+ aTK07vtZ7Haeh6zRYrVFVW4xWmzEbEU1pYl7bj+9bYbTO/E1eknjex47vcYPyeTurl o2lB7IlEe59VodSvzJlzmcIPvXEDhMuPIJnZhlEPNhUygZJMo1201s/1VpPHg/2N4U WyoY0rzmPb6pf1LSMX0Fl25waR/mCfVWDaonRYj/scwbKMV4CV7rSHt34EoStJ3GKy NRiBldOKwGbtsV85IuwWIH2i/miOHMm1tcjJHeu177YurtpwNF2zHvMxNYPCZ5Kcif B2dcHEhzAhmMw== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:37 +0000 Subject: [PATCH RFT v13 3/8] selftests: Provide helper header for shadow stack testing Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241203-clone3-shadow-stack-v13-3-93b89a81a5ed@kernel.org> References: <20241203-clone3-shadow-stack-v13-0-93b89a81a5ed@kernel.org> In-Reply-To: <20241203-clone3-shadow-stack-v13-0-93b89a81a5ed@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 , Valentin Schneider , Christian Brauner , Shuah Khan Cc: linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , jannh@google.com, bsegall@google.com, Yury Khrustalev , Wilco Dijkstra , linux-kselftest@vger.kernel.org, linux-api@vger.kernel.org, Mark Brown , Kees Cook , Kees Cook , Shuah Khan X-Mailer: b4 0.15-dev-9b746 X-Developer-Signature: v=1; a=openpgp-sha256; l=4486; i=broonie@kernel.org; h=from:subject:message-id; bh=ZPECVt2iZI6cgmwzVsOfP4QoLnc65CaYS1gJJRUNbtE=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FgGcROajf3eQG6tXQixIhMspbNP2c3rMnLSxWL xsTbJ1mJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RYAAKCRAk1otyXVSH0FDZB/ 4lvH9otzinBbbGrm6Vl/BKTfBDIrO94WhDfO51ncpghBjiCJIy/aJ9gPsH8w+k+m3v4T/k+5cTAD8X U/Sg7nFNcmv9O9p51slKiOiIf1q9QYCuVwwSL7nODXyjc5UhatCx/UDqZQMkHXIgLn3PQuSmraWjlN chGP2TQhBvPoGAgS7f9Vli4iEtR0lQDRvStu3Pl68cgURwUeAlSA6lifOZK4duSCpwFNkwWnm5z23D yxvpewjyJt0CGUzhjZnp6NjZc0PC+w04JswHHx7F9DoBBc+w6MHiUFF16x9MK9gimLbJrol91odJxl 2DeHDVJ9TmlQ9W/3sjdCQxslIzkwLg X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB While almost all users of shadow stacks should be relying on the dynamic linker and libc to enable the feature there are several low level test programs where it is useful to enable without any libc support, allowing testing without full system enablement. This low level testing is helpful during bringup of the support itself, and also in enabling coverage by automated testing without needing all system components in the target root filesystems to have enablement. Provide a header with helpers for this purpose, intended for use only by test programs directly exercising shadow stack interfaces. Reviewed-by: Rick Edgecombe Reviewed-by: Kees Cook Tested-by: Kees Cook Acked-by: Shuah Khan Signed-off-by: Mark Brown --- tools/testing/selftests/ksft_shstk.h | 98 ++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) diff --git a/tools/testing/selftests/ksft_shstk.h b/tools/testing/selftests/ksft_shstk.h new file mode 100644 index 0000000000000000000000000000000000000000..869ecea2bf3ea3d30cead9819d2b3a75f5397754 --- /dev/null +++ b/tools/testing/selftests/ksft_shstk.h @@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Helpers for shadow stack enablement, this is intended to only be + * used by low level test programs directly exercising interfaces for + * working with shadow stacks. + * + * Copyright (C) 2024 ARM Ltd. + */ + +#ifndef __KSFT_SHSTK_H +#define __KSFT_SHSTK_H + +#include + +/* This is currently only defined for x86 */ +#ifndef SHADOW_STACK_SET_TOKEN +#define SHADOW_STACK_SET_TOKEN (1ULL << 0) +#endif + +static bool shadow_stack_enabled; + +#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 ENABLE_SHADOW_STACK +static inline __attribute__((always_inline)) void enable_shadow_stack(void) +{ + int ret = ARCH_PRCTL(ARCH_SHSTK_ENABLE, ARCH_SHSTK_SHSTK); + if (ret == 0) + shadow_stack_enabled = true; +} + +#endif + +#ifdef __aarch64__ +#define PR_SET_SHADOW_STACK_STATUS 75 +# define PR_SHADOW_STACK_ENABLE (1UL << 0) + +#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; \ +}) + +#define ENABLE_SHADOW_STACK +static inline __attribute__((always_inline)) void enable_shadow_stack(void) +{ + int ret; + + ret = my_syscall2(__NR_prctl, PR_SET_SHADOW_STACK_STATUS, + PR_SHADOW_STACK_ENABLE); + if (ret == 0) + shadow_stack_enabled = true; +} + +#endif + +#ifndef __NR_map_shadow_stack +#define __NR_map_shadow_stack 453 +#endif + +#ifndef ENABLE_SHADOW_STACK +static inline void enable_shadow_stack(void) { } +#endif + +#endif