From patchwork Tue Dec 3 18:43:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892808 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 99B7D1FDE14; Tue, 3 Dec 2024 18:44:01 +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=1733251441; cv=none; b=bFUuFXC7PFsK6yCHJF0W0Z2e64MZtSVmSwvgt9hvAWQ4re5V9ci45YYyDgIPNToknm7bGLxshXMWxoPL9aLH9dcZAzgH3K4eKM5vqsYKLVxHzPRHRPznHJ7rlPmNDGbg2WEcl3TYznAJwfXp5kIz9soOBo986uC1QyLgYmWSSH8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251441; c=relaxed/simple; bh=2F2SLWPbEItzwDNJ6lJGW2XUKxCYFT2T3x6909uaSvM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=FfSNez6ZG+ecuzrR3Xw8SMWAhgOQTCV7QVtOJivQ3pnPnnoUJtHSokVeWumlSIkFRuhzFzIbqzFdK0Hs9Q1FFbSRTT3XhY4MzSLiykzvPOw0g6k5uGQIrLCRnKXdpJElBjCZlq9dUyH3TFGKc0CVDo6qScjtKNadcJa1T9oByG4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=L7SRIC88; 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="L7SRIC88" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1579C4CED9; Tue, 3 Dec 2024 18:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251441; bh=2F2SLWPbEItzwDNJ6lJGW2XUKxCYFT2T3x6909uaSvM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=L7SRIC880yz/IGMxWON1n9umYPwlvjvhs9EU2AUtrRV7jWuAcmJKUSnfiF6uCnTzP OBjmNcue9IfjVLnSJh/lHPY5I0XlErBVogzdatszD4VHadMMW4PRRhu5wtih2Ktte0 U11/on43GXTT1UEgoimACkBynrvml/0B5HnK1XtS04XgG3qMY8p/GDhqw7zzUARdXi sZlweO+2ImyaifCE6vrdn2cE3MQVkNWIDw5cV6TDMzrY6kPIjoDv2BS/agahZuNCtX z42WsYQKx+GeNL9ak781DcyItDOhy7XwBl4A+9ssc50zQdvyRDDyiVzbee4RAgRE8L CvCVLG7pLQnNg== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:35 +0000 Subject: [PATCH RFT v13 1/8] arm64/gcs: Return a success value from gcs_alloc_thread_stack() 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-v13-1-93b89a81a5ed@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 X-Mailer: b4 0.15-dev-9b746 X-Developer-Signature: v=1; a=openpgp-sha256; l=3931; i=broonie@kernel.org; h=from:subject:message-id; bh=2F2SLWPbEItzwDNJ6lJGW2XUKxCYFT2T3x6909uaSvM=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FfJWT4VLrCzptaKD81LQwOL2Sb++OZxhOZ8YAA ligurYiJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RXwAKCRAk1otyXVSH0GsuB/ 4gy8aQNRUzDKQ2VX96qmXwo37sxNVovVFnTRMFy14zLB9ekS03PO1mwBadD7NLDVMFM/FDPZgiN8ch xOnDsmhgaY4CErPMRv7BMKtLY0LwMHOR7uSXCYcN08I0pKLk+5pq+n/DxbWMmnzEQpKFa1rcEDasgt dMizQR8NM7FCTXaLAG0Dv5KkajzzqbxeANbQbqFmo+mbT0Zn6r+VlppSkLll1GgbR4vvYOqO2nqtU4 MRjczTvYYetWDhEXmv3EU4f1cvjG4v63QTnWKA/IB2WePWYERtbCn04k+PaMkmPllp6MS33zLU86WO Syj1Z1+GhL3/g6JZT2cloS8f76ckYr X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Currently as a result of templating from x86 code gcs_alloc_thread_stack() returns a pointer as an unsigned int however on arm64 we don't actually use this pointer value as anything other than a pass/fail flag. Simplify the interface to just return an int with 0 on success and a negative error code on failure. Acked-by: Deepak Gupta Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown --- arch/arm64/include/asm/gcs.h | 8 ++++---- arch/arm64/kernel/process.c | 8 ++++---- arch/arm64/mm/gcs.c | 8 ++++---- 3 files changed, 12 insertions(+), 12 deletions(-) diff --git a/arch/arm64/include/asm/gcs.h b/arch/arm64/include/asm/gcs.h index f50660603ecf5dc09a92740062df3a089b02b219..d8923b5f03b776252aca76ce316ef57399d71fa9 100644 --- a/arch/arm64/include/asm/gcs.h +++ b/arch/arm64/include/asm/gcs.h @@ -64,8 +64,8 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task) void gcs_set_el0_mode(struct task_struct *task); void gcs_free(struct task_struct *task); void gcs_preserve_current_state(void); -unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, - const struct kernel_clone_args *args); +int gcs_alloc_thread_stack(struct task_struct *tsk, + const struct kernel_clone_args *args); static inline int gcs_check_locked(struct task_struct *task, unsigned long new_val) @@ -91,8 +91,8 @@ static inline bool task_gcs_el0_enabled(struct task_struct *task) static inline void gcs_set_el0_mode(struct task_struct *task) { } static inline void gcs_free(struct task_struct *task) { } static inline void gcs_preserve_current_state(void) { } -static inline unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, - const struct kernel_clone_args *args) +static inline int gcs_alloc_thread_stack(struct task_struct *tsk, + const struct kernel_clone_args *args) { return -ENOTSUPP; } diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 2968a33bb3bc16208ff672590fd9a9a8d0b26b19..c217ab67e82baa212d008b62b876acf8b2b492d6 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -297,7 +297,7 @@ static void flush_gcs(void) static int copy_thread_gcs(struct task_struct *p, const struct kernel_clone_args *args) { - unsigned long gcs; + int ret; if (!system_supports_gcs()) return 0; @@ -305,9 +305,9 @@ static int copy_thread_gcs(struct task_struct *p, p->thread.gcs_base = 0; p->thread.gcs_size = 0; - gcs = gcs_alloc_thread_stack(p, args); - if (IS_ERR_VALUE(gcs)) - return PTR_ERR((void *)gcs); + ret = gcs_alloc_thread_stack(p, args); + if (ret != 0) + return ret; p->thread.gcs_el0_mode = current->thread.gcs_el0_mode; p->thread.gcs_el0_locked = current->thread.gcs_el0_locked; diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c index 5c46ec527b1cdaa8f52cff445d70ba0f8509d086..1f633a482558b59aac5427963d42b37fce08c8a6 100644 --- a/arch/arm64/mm/gcs.c +++ b/arch/arm64/mm/gcs.c @@ -38,8 +38,8 @@ static unsigned long gcs_size(unsigned long size) return max(PAGE_SIZE, size); } -unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, - const struct kernel_clone_args *args) +int gcs_alloc_thread_stack(struct task_struct *tsk, + const struct kernel_clone_args *args) { unsigned long addr, size; @@ -59,13 +59,13 @@ unsigned long gcs_alloc_thread_stack(struct task_struct *tsk, size = gcs_size(size); addr = alloc_gcs(0, size); if (IS_ERR_VALUE(addr)) - return addr; + return PTR_ERR((void *)addr); tsk->thread.gcs_base = addr; tsk->thread.gcs_size = size; tsk->thread.gcspr_el0 = addr + size - sizeof(u64); - return addr; + return 0; } SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsigned int, flags) From patchwork Tue Dec 3 18:43:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892809 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 24CD41FDE14; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HOmQ/MYd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DFDDEC4CED6; Tue, 3 Dec 2024 18:44:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251447; bh=ZEnTeNnz3soYJ8jfAeIX2G+RpIQ8/WUP7NzW6qh0PyE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=HOmQ/MYdc4rf52ZigX9MahM4ULEpJRU/8QkQgEig9ZquIHPW4nRGoTrAjd9ZrbAIB W0jxodOg0l0j3s0lotvxCucvkltBKZQyTAocQrLiCFK4QvO7kb66BiSBKfsAhbYTb+ 7wb6rRVsxe44qglKBcog26w35BeYxMtXCtcIpDU5qTvCLKBjL4L6tNL81fkfVZYk1K gaIAy2QhYmcKcdjwIOqL7qiOL1w7i+MKht3G3AMwu0OwtF6apJI7NQKTyHYSx7kvN2 YEADmtpzfMlPviENcY0W8OHjoDDNN6EYBEcceGc4srBNvURL3KuK5+LSXovyHBHqn3 VuwL73Fa0MHPw== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:36 +0000 Subject: [PATCH RFT v13 2/8] Documentation: userspace-api: Add shadow stack API documentation 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-v13-2-93b89a81a5ed@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=3258; i=broonie@kernel.org; h=from:subject:message-id; bh=ZEnTeNnz3soYJ8jfAeIX2G+RpIQ8/WUP7NzW6qh0PyE=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FfY4pgm2uLre1h902tbQAs/VMJe5teTGcpUhCy GPiV4MWJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RXwAKCRAk1otyXVSH0HV2B/ 44qfmh5aBH3h8IktPq0nTCPnatWS558g2Aar6WDEabay7IfM/pHRDm/45T7faWg27iKAHFhmNyLi26 O8Xr50LHWb+T4TUNlrnexb6p4oIa9EtTUriOhZ4DLHmUM1ttrFnRi2tVOhX4rUYIwKgpASLPyYK+dB FLYSbXH8on25PQOIixiGDUlPUkGz/b5jAmgm+3sl4PFE+s2G7CLgrXSjnFHqQuT2EVd82H/qy5i068 VhJMcCJ/ozXahM+ywWr1yvPYWEqSYYyiSNkIFSm/zdeie3meXTu6MVJDVRXY4pHRoKv8VeHg66L6UU fJkv6axxMZJQuUSUK7/Ik/v1D2Snlh X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB There are a number of architectures with shadow stack features which we are presenting to userspace with as consistent an API as we can (though there are some architecture specifics). Especially given that there are some important considerations for userspace code interacting directly with the feature let's provide some documentation covering the common aspects. Reviewed-by: Catalin Marinas Reviewed-by: Kees Cook Tested-by: Kees Cook Acked-by: Shuah Khan Acked-by: Yury Khrustalev Signed-off-by: Mark Brown --- Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/shadow_stack.rst | 42 ++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index 274cc7546efc2a042d2dc00aa67c71c52372179a..c39709bfba2c5682d0d1a22444db17c17bcf01ce 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -59,6 +59,7 @@ Everything else ELF netlink/index + shadow_stack sysfs-platform_profile vduse futex2 diff --git a/Documentation/userspace-api/shadow_stack.rst b/Documentation/userspace-api/shadow_stack.rst new file mode 100644 index 0000000000000000000000000000000000000000..9d0d4e79cfa7c47d3208dd53071a3d0b86c18575 --- /dev/null +++ b/Documentation/userspace-api/shadow_stack.rst @@ -0,0 +1,42 @@ +============= +Shadow Stacks +============= + +Introduction +============ + +Several architectures have features which provide backward edge +control flow protection through a hardware maintained stack, only +writeable by userspace through very limited operations. This feature +is referred to as shadow stacks on Linux, on x86 it is part of Intel +Control Enforcement Technology (CET), on arm64 it is Guarded Control +Stacks feature (FEAT_GCS) and for RISC-V it is the Zicfiss extension. +It is expected that this feature will normally be managed by the +system dynamic linker and libc in ways broadly transparent to +application code, this document covers interfaces and considerations. + + +Enabling +======== + +Shadow stacks default to disabled when a userspace process is +executed, they can be enabled for the current thread with a syscall: + + - For x86 the ARCH_SHSTK_ENABLE arch_prctl() + - For other architectures the PR_SET_SHADOW_STACK_ENABLE prctl() + +It is expected that this will normally be done by the dynamic linker. +Any new threads created by a thread with shadow stacks enabled will +themselves have shadow stacks enabled. + + +Enablement considerations +========================= + +- Returning from the function that enables shadow stacks without first + disabling them will cause a shadow stack exception. This includes + any syscall wrapper or other library functions, the syscall will need + to be inlined. +- A lock feature allows userspace to prevent disabling of shadow stacks. +- Those that change the stack context like longjmp() or use of ucontext + changes on signal return will need support from libc. 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 From patchwork Tue Dec 3 18:43:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892811 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 84E731FCFEF; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Oj/vuch1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E845C4CED8; Tue, 3 Dec 2024 18:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251460; bh=XJ1lYB2M3QMtlsbMI0uDc59eNgqxqc+bWvGg3bXFamc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Oj/vuch1aW9sGvShgZiky36J6D8/pm1zvEYl01XG+dPVS7scM18VK48J+XnD5egNm hZTdMDTndPloes6GGJlQj7hog4lYq1dcr73pau187d7IdOz7ctKSwF8xy/BPviK5++ czGomzM0uZqhiI1mlNiW8V1jRAPTedInyaFp31U2NHjaeIu8W10mFxXfJbNSPat0wS lPD/MZZPmmDBNbwTudVfkX0OTRBizsc9NJ6NXl3hRE1k7K8zdNvUns0V7XzEOGSL2f 5iRDbJs8ObS0GPoytyjkwMu581sIAWRr/LF89JPVGZeOQOEubVJcezMaKkYi5GSafK qwBMswycTFM0A== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:38 +0000 Subject: [PATCH RFT v13 4/8] fork: Add shadow stack support to clone3() 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-v13-4-93b89a81a5ed@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 X-Mailer: b4 0.15-dev-9b746 X-Developer-Signature: v=1; a=openpgp-sha256; l=16831; i=broonie@kernel.org; h=from:subject:message-id; bh=XJ1lYB2M3QMtlsbMI0uDc59eNgqxqc+bWvGg3bXFamc=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FhkTIq0+yOd+qkklAHsYJ+4Hkl1wIim8eJKX2N qaMkKTWJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RYQAKCRAk1otyXVSH0HnaB/ 9erRoWJiYgzyf4eZA0a1cbMhuMjxLXnPAVw/QmGBleymLbRz9FumYnHBFgbzL9h1vluiko4GS+NEFA uVaA9sczmmBQnVTF5cp7p8qcv55FZHoj0R42d+v9fF0+EeyqderX4I+VrBhp0rSVUKgAgV20vO8ndN QRJFMPld6iu1yHMjpP88Q34FPFBiEt/SeZPbYcrH1cestFDStD5GzG9OEJ1RYU0nztZxaRFjVvky1s UA66fscvKZm58xk+k09RCrAgxwEB0lcuXZmNINmiK+SKbsmNc70xic5ZR7Eka4wjaydlH9PUO8yRn6 8oUYQlmLV5ntWxReRwS5XQbhWz5oUz X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Unlike with the normal stack there is no API for configuring the the shadow stack for a new thread, instead the kernel will dynamically allocate a new shadow stack with the same size as the normal stack. This appears to be due to the shadow stack series having been in development since before the more extensible clone3() was added rather than anything more deliberate. Add a paramter to clone3() specifying the shadow stack pointer to use for the new thread, this is inconsistent with the way we specify the normal stack but during review concerns were expressed about having to identify where the shadow stack pointer should be placed especially in cases where the shadow stack has been previously active. If no shadow stack is specified then the existing implicit allocation behaviour is maintained. If a shadow stack pointer is specified then it is required to have an architecture defined token placed on the stack, this will be consumed by the new task. If no valid token is present then this will be reported with -EINVAL. This token prevents new threads being created pointing at the shadow stack of an existing running thread. If the architecture does not support shadow stacks the shadow stack pointer must be not be specified, architectures that do support the feature are expected to enforce the same requirement on individual systems that lack shadow stack support. Update the existing arm64 and x86 implementations to pay attention to the newly added arguments, in order to maintain compatibility we use the existing behaviour if no shadow stack is specified. Since we are now using more fields from the kernel_clone_args we pass that into the shadow stack code rather than individual fields. Portions of the x86 architecture code were written by Rick Edgecombe. Acked-by: Yury Khrustalev Signed-off-by: Mark Brown --- arch/arm64/mm/gcs.c | 54 +++++++++++++++++++++- arch/x86/include/asm/shstk.h | 11 +++-- arch/x86/kernel/process.c | 2 +- arch/x86/kernel/shstk.c | 57 +++++++++++++++++++++--- include/asm-generic/cacheflush.h | 11 +++++ include/linux/sched/task.h | 17 +++++++ include/uapi/linux/sched.h | 10 +++-- kernel/fork.c | 96 +++++++++++++++++++++++++++++++++++----- 8 files changed, 232 insertions(+), 26 deletions(-) diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c index 1f633a482558b59aac5427963d42b37fce08c8a6..c4e93b7ce05c5dfa1128923ad587f9b5a7fb0051 100644 --- a/arch/arm64/mm/gcs.c +++ b/arch/arm64/mm/gcs.c @@ -43,8 +43,24 @@ int gcs_alloc_thread_stack(struct task_struct *tsk, { unsigned long addr, size; - if (!system_supports_gcs()) + if (!system_supports_gcs()) { + if (args->shadow_stack_pointer) + return -EINVAL; + + return 0; + } + + /* + * If the user specified a GCS then use it, otherwise fall + * back to a default allocation strategy. Validation is done + * in arch_shstk_validate_clone(). + */ + if (args->shadow_stack_pointer) { + tsk->thread.gcs_base = 0; + tsk->thread.gcs_size = 0; + tsk->thread.gcspr_el0 = args->shadow_stack_pointer; return 0; + } if (!task_gcs_el0_enabled(tsk)) return 0; @@ -68,6 +84,42 @@ int gcs_alloc_thread_stack(struct task_struct *tsk, return 0; } +static bool gcs_consume_token(struct vm_area_struct *vma, struct page *page, + unsigned long user_addr) +{ + u64 expected = GCS_CAP(user_addr); + u64 *token = page_address(page) + offset_in_page(user_addr); + + if (!cmpxchg_to_user_page(vma, page, user_addr, token, expected, 0)) + return false; + set_page_dirty_lock(page); + + return true; +} + +int arch_shstk_validate_clone(struct task_struct *tsk, + struct vm_area_struct *vma, + struct page *page, + struct kernel_clone_args *args) +{ + unsigned long gcspr_el0; + int ret = 0; + + /* Ensure that a token written as a result of a pivot is visible */ + gcsb_dsync(); + + gcspr_el0 = args->shadow_stack_pointer; + if (!gcs_consume_token(vma, page, gcspr_el0)) + return -EINVAL; + + tsk->thread.gcspr_el0 = gcspr_el0 + sizeof(u64); + + /* Ensure that our token consumption visible */ + gcsb_dsync(); + + return ret; +} + SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsigned int, flags) { unsigned long alloc_size; diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h index 4cb77e004615dff003426a2eb594460ca1015f4e..252feeda69991e939942c74556e23e27c835e766 100644 --- a/arch/x86/include/asm/shstk.h +++ b/arch/x86/include/asm/shstk.h @@ -6,6 +6,7 @@ #include struct task_struct; +struct kernel_clone_args; struct ksignal; #ifdef CONFIG_X86_USER_SHADOW_STACK @@ -16,8 +17,8 @@ struct thread_shstk { long shstk_prctl(struct task_struct *task, int option, unsigned long arg2); void reset_thread_features(void); -unsigned long shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags, - unsigned long stack_size); +unsigned long shstk_alloc_thread_stack(struct task_struct *p, + const struct kernel_clone_args *args); void shstk_free(struct task_struct *p); int setup_signal_shadow_stack(struct ksignal *ksig); int restore_signal_shadow_stack(void); @@ -28,8 +29,10 @@ static inline long shstk_prctl(struct task_struct *task, int option, unsigned long arg2) { return -EINVAL; } static inline void reset_thread_features(void) {} static inline unsigned long shstk_alloc_thread_stack(struct task_struct *p, - unsigned long clone_flags, - unsigned long stack_size) { return 0; } + const struct kernel_clone_args *args) +{ + return 0; +} static inline void shstk_free(struct task_struct *p) {} static inline int setup_signal_shadow_stack(struct ksignal *ksig) { return 0; } static inline int restore_signal_shadow_stack(void) { return 0; } diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index f63f8fd00a91f3d1171f307b92179556ba2d716d..59456ab8d93faee29c3b223b64eb41659df76032 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -207,7 +207,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) * is disabled, new_ssp will remain 0, and fpu_clone() will know not to * update it. */ - new_ssp = shstk_alloc_thread_stack(p, clone_flags, args->stack_size); + new_ssp = shstk_alloc_thread_stack(p, args); if (IS_ERR_VALUE(new_ssp)) return PTR_ERR((void *)new_ssp); diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c index 059685612362d7b1865eabf400888fbfa0659c1e..056e2c9ec30531d0901297da07f1842b47d2fcd5 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -191,18 +191,65 @@ void reset_thread_features(void) current->thread.features_locked = 0; } -unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long clone_flags, - unsigned long stack_size) +int arch_shstk_validate_clone(struct task_struct *t, + struct vm_area_struct *vma, + struct page *page, + struct kernel_clone_args *args) +{ + /* + * SSP is aligned, so reserved bits and mode bit are a zero, just mark + * the token 64-bit. + */ + void *maddr = kmap_local_page(page); + int offset; + unsigned long addr, ssp; + u64 expected; + + if (!features_enabled(ARCH_SHSTK_SHSTK)) + return 0; + + ssp = args->shadow_stack_pointer; + addr = ssp - SS_FRAME_SIZE; + expected = ssp | BIT(0); + offset = offset_in_page(addr); + + if (!cmpxchg_to_user_page(vma, page, addr, (unsigned long *)(maddr + offset), + expected, 0)) + return -EINVAL; + set_page_dirty_lock(page); + + return 0; +} + +unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, + const struct kernel_clone_args *args) { struct thread_shstk *shstk = &tsk->thread.shstk; + unsigned long clone_flags = args->flags; unsigned long addr, size; /* * If shadow stack is not enabled on the new thread, skip any - * switch to a new shadow stack. + * implicit switch to a new shadow stack and reject attempts to + * explicitly specify one. */ - if (!features_enabled(ARCH_SHSTK_SHSTK)) + if (!features_enabled(ARCH_SHSTK_SHSTK)) { + if (args->shadow_stack_pointer) + return (unsigned long)ERR_PTR(-EINVAL); + return 0; + } + + /* + * If the user specified a shadow stack then use it, otherwise + * fall back to a default allocation strategy. Validation is + * done in arch_shstk_validate_clone(). + */ + if (args->shadow_stack_pointer) { + shstk->base = 0; + shstk->size = 0; + return args->shadow_stack_pointer; + } /* * For CLONE_VFORK the child will share the parents shadow stack. @@ -222,7 +269,7 @@ unsigned long shstk_alloc_thread_stack(struct task_struct *tsk, unsigned long cl if (!(clone_flags & CLONE_VM)) return 0; - size = adjust_shstk_size(stack_size); + size = adjust_shstk_size(args->stack_size); addr = alloc_shstk(0, size, 0, false); if (IS_ERR_VALUE(addr)) return addr; diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h index 7ee8a179d1036e1d8010b8b18a8f3022e41c1695..96cc0c7a5c90fd7e899d0c5fe7c706302265efcf 100644 --- a/include/asm-generic/cacheflush.h +++ b/include/asm-generic/cacheflush.h @@ -124,4 +124,15 @@ static inline void flush_cache_vunmap(unsigned long start, unsigned long end) } while (0) #endif +#ifndef cmpxchg_to_user_page +#define cmpxchg_to_user_page(vma, page, vaddr, ptr, old, new) \ +({ \ + bool ret; \ + \ + ret = try_cmpxchg(ptr, &old, new); \ + flush_icache_user_page(vma, page, vaddr, sizeof(*ptr)); \ + ret; \ +}) +#endif + #endif /* _ASM_GENERIC_CACHEFLUSH_H */ diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 0f2aeb37bbb047335a399326b31bc8df81b75a3a..cd36389619d5c97401f7b90e177c6027c232783b 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -16,6 +16,7 @@ struct task_struct; struct rusage; union thread_union; struct css_set; +struct vm_area_struct; /* All the bits taken by the old clone syscall. */ #define CLONE_LEGACY_FLAGS 0xffffffffULL @@ -43,6 +44,7 @@ struct kernel_clone_args { void *fn_arg; struct cgroup *cgrp; struct css_set *cset; + unsigned long shadow_stack_pointer; }; /* @@ -236,4 +238,19 @@ static inline void task_unlock(struct task_struct *p) DEFINE_GUARD(task_lock, struct task_struct *, task_lock(_T), task_unlock(_T)) +#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK +int arch_shstk_validate_clone(struct task_struct *p, + struct vm_area_struct *vma, + struct page *page, + struct kernel_clone_args *args); +#else +static inline int arch_shstk_validate_clone(struct task_struct *p, + struct vm_area_struct *vma, + struct page *page, + struct kernel_clone_args *args) +{ + return 0; +} +#endif + #endif /* _LINUX_SCHED_TASK_H */ diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index 359a14cc76a4038aeacef14b2915d5ce60d0cf44..586a1c05a4e4ca05584d4d500223bcf6c3add54c 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -84,6 +84,8 @@ * kernel's limit of nested PID namespaces. * @cgroup: If CLONE_INTO_CGROUP is specified set this to * a file descriptor for the cgroup. + * @shadow_stack_pointer: Value to use for shadow stack pointer in the + * child process. * * The structure is versioned by size and thus extensible. * New struct members must go at the end of the struct and @@ -101,12 +103,14 @@ struct clone_args { __aligned_u64 set_tid; __aligned_u64 set_tid_size; __aligned_u64 cgroup; + __aligned_u64 shadow_stack_pointer; }; #endif -#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */ -#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */ -#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */ +#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */ +#define CLONE_ARGS_SIZE_VER1 80 /* sizeof second published struct */ +#define CLONE_ARGS_SIZE_VER2 88 /* sizeof third published struct */ +#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */ /* * Scheduling policies diff --git a/kernel/fork.c b/kernel/fork.c index 1450b461d196a1efee0e120780467a96f6c7d491..6ef945c7d4220f0838d004a8b37615cccc91b7da 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2128,6 +2128,51 @@ static void rv_task_fork(struct task_struct *p) #define rv_task_fork(p) do {} while (0) #endif +static int shstk_validate_clone(struct task_struct *p, + struct kernel_clone_args *args) +{ + struct mm_struct *mm; + struct vm_area_struct *vma; + struct page *page; + unsigned long addr; + int ret; + + if (!IS_ENABLED(CONFIG_ARCH_HAS_USER_SHADOW_STACK)) + return 0; + + if (!args->shadow_stack_pointer) + return 0; + + mm = get_task_mm(p); + if (!mm) + return -EFAULT; + + mmap_read_lock(mm); + + addr = untagged_addr_remote(mm, args->shadow_stack_pointer); + page = get_user_page_vma_remote(mm, addr, FOLL_FORCE | FOLL_WRITE, + &vma); + if (IS_ERR(page)) { + ret = -EFAULT; + goto out; + } + + if (!(vma->vm_flags & VM_SHADOW_STACK) || + !(vma->vm_flags & VM_WRITE)) { + ret = -EFAULT; + goto out_page; + } + + ret = arch_shstk_validate_clone(p, vma, page, args); + +out_page: + put_page(page); +out: + mmap_read_unlock(mm); + mmput(mm); + return ret; +} + /* * This creates a new process as a copy of the old one, * but does not actually start it yet. @@ -2402,6 +2447,9 @@ __latent_entropy struct task_struct *copy_process( if (retval) goto bad_fork_cleanup_namespaces; retval = copy_thread(p, args); + if (retval) + goto bad_fork_cleanup_io; + retval = shstk_validate_clone(p, args); if (retval) goto bad_fork_cleanup_io; @@ -2965,7 +3013,9 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, CLONE_ARGS_SIZE_VER1); BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) != CLONE_ARGS_SIZE_VER2); - BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2); + BUILD_BUG_ON(offsetofend(struct clone_args, shadow_stack_pointer) != + CLONE_ARGS_SIZE_VER3); + BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER3); if (unlikely(usize > PAGE_SIZE)) return -E2BIG; @@ -2998,16 +3048,17 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, return -EINVAL; *kargs = (struct kernel_clone_args){ - .flags = args.flags, - .pidfd = u64_to_user_ptr(args.pidfd), - .child_tid = u64_to_user_ptr(args.child_tid), - .parent_tid = u64_to_user_ptr(args.parent_tid), - .exit_signal = args.exit_signal, - .stack = args.stack, - .stack_size = args.stack_size, - .tls = args.tls, - .set_tid_size = args.set_tid_size, - .cgroup = args.cgroup, + .flags = args.flags, + .pidfd = u64_to_user_ptr(args.pidfd), + .child_tid = u64_to_user_ptr(args.child_tid), + .parent_tid = u64_to_user_ptr(args.parent_tid), + .exit_signal = args.exit_signal, + .stack = args.stack, + .stack_size = args.stack_size, + .tls = args.tls, + .set_tid_size = args.set_tid_size, + .cgroup = args.cgroup, + .shadow_stack_pointer = args.shadow_stack_pointer, }; if (args.set_tid && @@ -3048,6 +3099,27 @@ static inline bool clone3_stack_valid(struct kernel_clone_args *kargs) return true; } +/** + * clone3_shadow_stack_valid - check and prepare shadow stack + * @kargs: kernel clone args + * + * Verify that shadow stacks are only enabled if supported. + */ +static inline bool clone3_shadow_stack_valid(struct kernel_clone_args *kargs) +{ + if (!kargs->shadow_stack_pointer) + return true; + + if (!IS_ALIGNED(kargs->shadow_stack_pointer, sizeof(void *))) + return false; + + /* + * The architecture must check support on the specific + * machine. + */ + return IS_ENABLED(CONFIG_ARCH_HAS_USER_SHADOW_STACK); +} + static bool clone3_args_valid(struct kernel_clone_args *kargs) { /* Verify that no unknown flags are passed along. */ @@ -3070,7 +3142,7 @@ static bool clone3_args_valid(struct kernel_clone_args *kargs) kargs->exit_signal) return false; - if (!clone3_stack_valid(kargs)) + if (!clone3_stack_valid(kargs) || !clone3_shadow_stack_valid(kargs)) return false; return true; From patchwork Tue Dec 3 18:43:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892812 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 90720205E14; Tue, 3 Dec 2024 18:44:26 +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=1733251466; cv=none; b=IkaeB3HYEaZCfN2wkfiARa0Pt/sfwchibeuuXeLXqtdCuyfdONkGQhHSuwoj0HRj1zoYypm62s0VNnsaH70Jb+lZinrVExZa1ocrkuXYuJ31YDq3HgfX/h+R+Hr+iXRbV4BDKWltNVZLY/vZcoK7t85YbBPvaILKkjX27Wh5oYU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251466; c=relaxed/simple; bh=PnhVCE63r5J0w6Q+lF8rA/22EDQWPUEiFQtbWxOidH8=; 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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=1170; i=broonie@kernel.org; h=from:subject:message-id; bh=PnhVCE63r5J0w6Q+lF8rA/22EDQWPUEiFQtbWxOidH8=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FiPGuGG9F8YqvPDKVh5qYqoyw05th4BGvH6a8z bsztwliJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RYgAKCRAk1otyXVSH0BR9B/ 91Y4vEiFtJDrVZtxCfz/elE4eUMeO8Z3NjLy1acF17Kl7VcZaizZpoWSItRK6EeNambZMLoDkgHuvk betvtwkStk6yptW/hHSEbTkCTPh4L3ib0AIYywdgT57xDOLg7MRFWwyNO4BuYtC5Xc7G6bCHSwLlHm GSln1PsLcLbR732G2s6XZO02tYjzGRI0JJrwgZiXMK9zQfPtdSSLHaA7R9egPEKUUzfFqJDgZP9Lbs HnwInzbTtSwRhg5P8YAxu3QzJ0PyQ6aPTOpanGN6PYdqLJXln5RkGgMRlkvE+cYtIcmKWN5myCgf4z afTLrZI/VX77BpCWkXpjXRvYfTgZZh X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB Since there were widespread issues with output not being flushed the kselftest framework was modified to explicitly set the output streams unbuffered in commit 58e2847ad2e6 ("selftests: line buffer test program's stdout") so there is no need to explicitly flush in the clone3 tests. Reviewed-by: Kees Cook Tested-by: Kees Cook Acked-by: Shuah Khan Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown --- tools/testing/selftests/clone3/clone3_selftests.h | 2 -- 1 file changed, 2 deletions(-) diff --git a/tools/testing/selftests/clone3/clone3_selftests.h b/tools/testing/selftests/clone3/clone3_selftests.h index 3d2663fe50ba56f011629e4f2eb68a72bcceb087..39b5dcba663c30b9fc2542d9a0d2686105ce5761 100644 --- a/tools/testing/selftests/clone3/clone3_selftests.h +++ b/tools/testing/selftests/clone3/clone3_selftests.h @@ -35,8 +35,6 @@ struct __clone_args { static pid_t sys_clone3(struct __clone_args *args, size_t size) { - fflush(stdout); - fflush(stderr); return syscall(__NR_clone3, args, size); } From patchwork Tue Dec 3 18:43:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892813 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 D2DB71FDE19; Tue, 3 Dec 2024 18:44:32 +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=1733251472; cv=none; b=Jca76zVdV/SUU+yWg1LRKj2kDdabaS6n4xzM7Iu2bBU7ZvNV028hmDeUx+MeZ/vbcQx8tTEFDiSEIv80/fuT0xGzRTyNpU1F8r1xNrKtrvT5pe7FgTj+SgvIDCNmUqCETKprrXuunvHkOGlH1bNnAOiVyXFXSKaKrr9nL0Fu8Zw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251472; c=relaxed/simple; bh=wcvwqUbnOLAAxDrogxdDS6u/ZDM3Aldxt+7Gj0ApJNU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=WHD0fSwLU+F6ooRlo/tr+sQLe0vhSyyQGf7WaKv43RBggiQP5z+M3UQL/Hat01px5XgM8viRm6n9gGiM3awMq6EILvgU5fkVNupG8mkuoy+BHlEjDBW47VvLBx5i6Td7b6rco9wo6Gvs7wFCWYNCFGM1PNPByukNxCX/9Jw2xCU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=m6ad1Wmf; 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="m6ad1Wmf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C7DEC4CED8; Tue, 3 Dec 2024 18:44:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251472; bh=wcvwqUbnOLAAxDrogxdDS6u/ZDM3Aldxt+7Gj0ApJNU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=m6ad1Wmf0QLT8Yio+7MiU2MoKuwQBcetDG6UU/lU96QJRniOweUnnaAWF0+3nLR4L X8PpS3oXc+KIBDeMsL0HmtJjgCvtOWo3LfsaRf6jBgqzIVk1OmQftNJmJJZBvwrghl /LyIkViMWJivAyrqj4Tt2yg3OJ33RagXSpiq0PnaWhtpwvfyoHOXEKIJi03aoRUSpb k3LDISxTKjcmk4LZAAv/H8yayFtixG7ACuFqpgKQu4OGiOIG0bvRWwqirCO7PZqCsO 9LbVNOZwMqA+Tu3+XA0eIWls03T1Sbav5cpV5VaqA4++DDTvtxLMPasGJg7HwgQY3Z FU11va1p8Ct1w== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:40 +0000 Subject: [PATCH RFT v13 6/8] selftests/clone3: Factor more of main loop into test_clone3() 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-v13-6-93b89a81a5ed@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=3987; i=broonie@kernel.org; h=from:subject:message-id; bh=wcvwqUbnOLAAxDrogxdDS6u/ZDM3Aldxt+7Gj0ApJNU=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FjepGm46ioXPnFMh/Zk8OmFJ7hVQ1sXANlbjYV dG94fYyJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RYwAKCRAk1otyXVSH0PwWB/ 48fZ9j+CnInG5ZuBXf7OgtmBL5NuEpshTclrQcj/5wdrqalO1tcAWCmU8gTNQuKUzB35ljXHEyJvl1 Cbn0z1xUXzQpQbIHv+8AYA1CTFFwMrzrP31Bmppyq7LA1MdAbCjWtwFzI27+FQQfdoRqj2aWFsecKk /6+BS5cOaBwkPOYVROhr5ccZju96vssIb6qSSnWWzDMReHjzcUEnRkttYHqQCWFsutEzUQYRvfuKjq Cap1KiG7a8l8oCo15mPi6otX2aqYWUT/lxwHAuCSl3P5hmQ+0r59F6WplXocFvHSudrJe0i8msoioJ ajNNIJvjejIxuKnqOagemk8AINctGy X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB In order to make it easier to add more configuration for the tests and more support for runtime detection of when tests can be run pass the structure describing the tests into test_clone3() rather than picking the arguments out of it and have that function do all the per-test work. No functional change. Reviewed-by: Kees Cook Tested-by: Kees Cook Acked-by: Shuah Khan Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown --- tools/testing/selftests/clone3/clone3.c | 77 ++++++++++++++++----------------- 1 file changed, 37 insertions(+), 40 deletions(-) diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c index e61f07973ce5e27aff30047b35e03b1b51875c15..e066b201fa64eb17c55939b7cec18ac5d109613b 100644 --- a/tools/testing/selftests/clone3/clone3.c +++ b/tools/testing/selftests/clone3/clone3.c @@ -30,6 +30,19 @@ enum test_mode { CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG, }; +typedef bool (*filter_function)(void); +typedef size_t (*size_function)(void); + +struct test { + const char *name; + uint64_t flags; + size_t size; + size_function size_function; + int expected; + enum test_mode test_mode; + filter_function filter; +}; + static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) { struct __clone_args args = { @@ -109,30 +122,40 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) return 0; } -static bool test_clone3(uint64_t flags, size_t size, int expected, - enum test_mode test_mode) +static void test_clone3(const struct test *test) { + size_t size; int ret; + if (test->filter && test->filter()) { + ksft_test_result_skip("%s\n", test->name); + return; + } + + if (test->size_function) + size = test->size_function(); + else + size = test->size; + + ksft_print_msg("Running test '%s'\n", test->name); + ksft_print_msg( "[%d] Trying clone3() with flags %#" PRIx64 " (size %zu)\n", - getpid(), flags, size); - ret = call_clone3(flags, size, test_mode); + getpid(), test->flags, size); + ret = call_clone3(test->flags, size, test->test_mode); ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n", - getpid(), ret, expected); - if (ret != expected) { + getpid(), ret, test->expected); + if (ret != test->expected) { ksft_print_msg( "[%d] Result (%d) is different than expected (%d)\n", - getpid(), ret, expected); - return false; + getpid(), ret, test->expected); + ksft_test_result_fail("%s\n", test->name); + return; } - return true; + ksft_test_result_pass("%s\n", test->name); } -typedef bool (*filter_function)(void); -typedef size_t (*size_function)(void); - static bool not_root(void) { if (getuid() != 0) { @@ -160,16 +183,6 @@ static size_t page_size_plus_8(void) return getpagesize() + 8; } -struct test { - const char *name; - uint64_t flags; - size_t size; - size_function size_function; - int expected; - enum test_mode test_mode; - filter_function filter; -}; - static const struct test tests[] = { { .name = "simple clone3()", @@ -319,24 +332,8 @@ int main(int argc, char *argv[]) ksft_set_plan(ARRAY_SIZE(tests)); test_clone3_supported(); - for (i = 0; i < ARRAY_SIZE(tests); i++) { - if (tests[i].filter && tests[i].filter()) { - ksft_test_result_skip("%s\n", tests[i].name); - continue; - } - - if (tests[i].size_function) - size = tests[i].size_function(); - else - size = tests[i].size; - - ksft_print_msg("Running test '%s'\n", tests[i].name); - - ksft_test_result(test_clone3(tests[i].flags, size, - tests[i].expected, - tests[i].test_mode), - "%s\n", tests[i].name); - } + for (i = 0; i < ARRAY_SIZE(tests); i++) + test_clone3(&tests[i]); ksft_finished(); } From patchwork Tue Dec 3 18:43:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892814 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 E2AF71FE444; Tue, 3 Dec 2024 18:44:38 +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=1733251479; cv=none; b=tCxrTDQMEF63+/m2qQN+obbo7luPTx3LUjes96yyCrxeYrruMuYZe0XYx8rfOzrozCdK5PmNwpQBUbLJdGaxSVAQVFCwwuJtNM5scaNNJyBN/1AdbXFRumOx505T6ND0T1wU+k0/B5gRHGjBVLSCx8pgYg3cECBMDRhjdZdGF2o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251479; c=relaxed/simple; bh=3K2UKwx+vuFRYwPgSWWdw27/XxZ/PQnIsnZQ3nrGTtc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=diFaM3ajOxjMGLbrf5+2ppZ5/RIhXMpTQ+6Ha0VGictOrKqoru9/oXzVDjGz+pFZoksYg/L1MlWAgI7k4Sk2a1IKuKwGwaP1CDEZ/4v0JOlWJGppmjt7RXSkiH7Gj1os0Tg0jqg1zGEf/gHXJxCmVQe43X6AW3Fei/H2e+E09j8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nIoTsrO3; 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="nIoTsrO3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFD65C4CED9; Tue, 3 Dec 2024 18:44:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251478; bh=3K2UKwx+vuFRYwPgSWWdw27/XxZ/PQnIsnZQ3nrGTtc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=nIoTsrO35egBGyHSoEHIzZBuCtwVvIhL1ASRJ7hWiu4yyWWqFpaqgkvASpqrWy7aI t/4Ntsq7U9WTstU8+DpcqPv+PUyS8GtuKi2chM2mZJrq0BBaCeWVnw6z3y7ulMjJ2n tQF0RIFVDl7gRhoF4BP2VNslqPdEhXWshblUpCEvRZ2rGrULTc1k2CLEtxrBoEX5Xs +31kWwppvfwFx4GQVxWR87mg2UQULMaX7dqqxm+XGdjOdU0M1hDsXHrqZULB+Eq8tL soty2ulCvpruEAAeQ8T39CovI+AWG96q4gQofYxqNDnyhBLZBy1c3unCegI2dgQJ8M HTU7u0bEmbkpQ== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:41 +0000 Subject: [PATCH RFT v13 7/8] selftests/clone3: Allow tests to flag if -E2BIG is a valid error code 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-v13-7-93b89a81a5ed@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=2131; i=broonie@kernel.org; h=from:subject:message-id; bh=3K2UKwx+vuFRYwPgSWWdw27/XxZ/PQnIsnZQ3nrGTtc=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FjO+RUyrRU5i3S6IrLR2NQaXuoRwl4o5L4r16y MEL2/7iJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RYwAKCRAk1otyXVSH0P2tB/ 4tYfKtZXuAIPpEeqmCQmIZpyU7d+UAMDuEkgHzxoSlrDJ8M65bNnUBRBeDw6Cs+lLLkc8cYQWT9Arf Oh9Ve2hvvpQbdzCMeCYzkeaxLx2pf5m6MM/Ceq0uByfcAbeub1ONDh7cRsskDBy74zhHZTn65RYv2w 3XGb/AHq264k+77m6xXOtd1A/0BklMr2dLs5kS3f3xiOgqASDtbWM//fL+Pju7t2HXW30nuEeUcWJv No+MLmtgFtsVhc7XuhfFLUUG+TuUwtqQLzoOsGXXPz41PskX2hDcjO+Xd6fnMIQkinfZnRGgjcU2T/ 6DYbKyz6Nv9/31E2Y+wy26M56Eb/lQ X-Developer-Key: i=broonie@kernel.org; a=openpgp; fpr=3F2568AAC26998F9E813A1C5C3F436CA30F5D8EB The clone_args structure is extensible, with the syscall passing in the length of the structure. Inside the kernel we use copy_struct_from_user() to read the struct but this has the unfortunate side effect of silently accepting some overrun in the structure size providing the extra data is all zeros. This means that we can't discover the clone3() features that the running kernel supports by simply probing with various struct sizes. We need to check this for the benefit of test systems which run newer kselftests on old kernels. Add a flag which can be set on a test to indicate that clone3() may return -E2BIG due to the use of newer struct versions. Currently no tests need this but it will become an issue for testing clone3() support for shadow stacks, the support for shadow stacks is already present on x86. Reviewed-by: Kees Cook Tested-by: Kees Cook Acked-by: Shuah Khan Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown --- tools/testing/selftests/clone3/clone3.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c index e066b201fa64eb17c55939b7cec18ac5d109613b..5b8b7d640e70132242fc6939450669acd0c534f9 100644 --- a/tools/testing/selftests/clone3/clone3.c +++ b/tools/testing/selftests/clone3/clone3.c @@ -39,6 +39,7 @@ struct test { size_t size; size_function size_function; int expected; + bool e2big_valid; enum test_mode test_mode; filter_function filter; }; @@ -146,6 +147,11 @@ static void test_clone3(const struct test *test) ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n", getpid(), ret, test->expected); if (ret != test->expected) { + if (test->e2big_valid && ret == -E2BIG) { + ksft_print_msg("Test reported -E2BIG\n"); + ksft_test_result_skip("%s\n", test->name); + return; + } ksft_print_msg( "[%d] Result (%d) is different than expected (%d)\n", getpid(), ret, test->expected); From patchwork Tue Dec 3 18:43:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 13892815 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 3E0D01FECA4; Tue, 3 Dec 2024 18:44:45 +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=1733251485; cv=none; b=ZYzWE/0QTkLj8M8WtDjQ0DA7PxLiI8T1cd9532Iff7FzoBG3V9KPVnmNIKrYT9C1kTq0FmtEUVyNQm1SbwB4DdCFFPfS4w7jvVA1NNb1HJO7/bWNxqYtUIPjBra+gdgSMsfkaZxoBFxEWNQpZQdsQkMuEHwIrQ12s8nCfneBfVM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733251485; c=relaxed/simple; bh=p3DzkDVZP2SFkK3VI5qaeiKq62xeJDdDTo+pXAW1T3g=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=fcIaKhEDxELNnY8mNIWbcx2s3JoszeOmMFymhQ4ftDtyxdhdIKBqbeusPeqcfqoTTiPww5MPnH4wuygAv9YY2wiJZqxGni/0sFqZU9PtMUTN17jmFHH9MgWIrbLr/9okueMNOC2CH1ts5A8fxrf7kAvjrPLJuo8uXicnSbhjME0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cRtRONcq; 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="cRtRONcq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F909C4CED8; Tue, 3 Dec 2024 18:44:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733251484; bh=p3DzkDVZP2SFkK3VI5qaeiKq62xeJDdDTo+pXAW1T3g=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=cRtRONcqr0q+YLq6k7S3xnLtANTRzDq+Vu7NYJO+CZEJLliTqMiOKRw+HosgNiSib QTFk502s6voIVCzaeCWSSzDLXVUEujFScsUKKF10x1qTVSkSf3ATEhGSu7uoWkKGKQ XT6KKuz8gEBRJ0RvTsVSZXZEyuCUz0ZgWznGCsU6/51I+lryRsFBAFZB1VJw/xRdgv OnlSGSdvRGRPAidcP8PrPRbPVgvAMwx1GZHyEeRXPoIg0bqYYG43VQ1aNTI+WzZLbY zEKEKHIkffhMJ4teVSd/SZwKdrpDu1Dr5FR0fXkX1TLNLiFC9rQS92In5VhJEoz6/t GZR9ks4xGp5nw== From: Mark Brown Date: Tue, 03 Dec 2024 18:43:42 +0000 Subject: [PATCH RFT v13 8/8] selftests/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: <20241203-clone3-shadow-stack-v13-8-93b89a81a5ed@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 , Shuah Khan X-Mailer: b4 0.15-dev-9b746 X-Developer-Signature: v=1; a=openpgp-sha256; l=10296; i=broonie@kernel.org; h=from:subject:message-id; bh=p3DzkDVZP2SFkK3VI5qaeiKq62xeJDdDTo+pXAW1T3g=; b=owEBbQGS/pANAwAKASTWi3JdVIfQAcsmYgBnT1FkefVjlQJeh4HGx4nCsNJ0Kz6k0tMk3rQC8PZL 4DwRewyJATMEAAEKAB0WIQSt5miqZ1cYtZ/in+ok1otyXVSH0AUCZ09RZAAKCRAk1otyXVSH0HXxB/ 97+gFJ4ckAXVv6ZbGYmi4WtUfmtVwvv9u2nql5u+ctKhoFvtDLt9b9TpnUXooA7fq6fgec/mE/9PzF wN+T65o3R0pywMoyVHMvVsqBx2XJlo22uCiqjy5Dz+xW5fvqKCrIsjgYvclboFzD5JUVLP/6v+LRBt NBldj4eNGiEDZX0fQLA2cbNsa3GKOKKQRpJH0u8bSxQcU9ufJUL51J3JA17s/1Z9wTa3udiZZ5ISJn 0MCqmWRrsSMcx86teMHu0zWV6vozmEg2QPOgGaukKCpJFim42H+c2JNvop2HiAvNs59DyboUOCukJo yJraeQObRUI5yFTh1jpR4371QZ5r9L 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. We check that a user specified shadow stack can be provided, and that invalid combinations of parameters are rejected. 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. In order to allow testing of user configured shadow stacks on architectures with that feature we need to ensure that we do not return from the function where the clone3() syscall is called in the child process, doing so would trigger a shadow stack underflow. To do this we use inline assembly rather than the standard syscall wrapper to call clone3(). In order to avoid surprises we also use a syscall rather than the libc exit() function., this should be overly cautious. Acked-by: Shuah Khan Signed-off-by: Mark Brown --- tools/testing/selftests/clone3/clone3.c | 143 +++++++++++++++++++++- tools/testing/selftests/clone3/clone3_selftests.h | 63 ++++++++++ 2 files changed, 205 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c index 5b8b7d640e70132242fc6939450669acd0c534f9..b0378d7418cc8b00caebc6f92f58280bc04b0f80 100644 --- a/tools/testing/selftests/clone3/clone3.c +++ b/tools/testing/selftests/clone3/clone3.c @@ -3,6 +3,7 @@ /* Based on Christian Brauner's clone3() example */ #define _GNU_SOURCE +#include #include #include #include @@ -11,6 +12,7 @@ #include #include #include +#include #include #include #include @@ -19,8 +21,12 @@ #include #include "../kselftest.h" +#include "../ksft_shstk.h" #include "clone3_selftests.h" +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 +34,10 @@ 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, + CLONE3_ARGS_SHADOW_STACK_MISALIGNED, + CLONE3_ARGS_SHADOW_STACK_NO_TOKEN, + CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY, }; typedef bool (*filter_function)(void); @@ -44,6 +54,44 @@ struct test { filter_function filter; }; + +/* + * 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 ret; + + ret = syscall(__NR_map_shadow_stack, 0, getpagesize(), 0); + if (ret == -1) { + ksft_print_msg("map_shadow_stack() not supported\n"); + } else if ((void *)ret == 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"); + } +} + +static void *get_shadow_stack_page(unsigned long flags) +{ + unsigned long long page; + + page = syscall(__NR_map_shadow_stack, 0, getpagesize(), flags); + if ((void *)page == MAP_FAILED) { + ksft_print_msg("map_shadow_stack() failed: %d\n", errno); + return 0; + } + + return (void *)page; +} + static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) { struct __clone_args args = { @@ -57,6 +105,7 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) } args_ext; pid_t pid = -1; + void *p; int status; memset(&args_ext, 0, sizeof(args_ext)); @@ -89,6 +138,26 @@ 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: + p = get_shadow_stack_page(SHADOW_STACK_SET_TOKEN); + p += getpagesize() - sizeof(void *); + args.shadow_stack_pointer = (unsigned long long)p; + break; + case CLONE3_ARGS_SHADOW_STACK_MISALIGNED: + p = get_shadow_stack_page(SHADOW_STACK_SET_TOKEN); + p += getpagesize() - sizeof(void *) - 1; + args.shadow_stack_pointer = (unsigned long long)p; + break; + case CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY: + p = malloc(getpagesize()); + p += getpagesize() - sizeof(void *); + args.shadow_stack_pointer = (unsigned long long)p; + break; + case CLONE3_ARGS_SHADOW_STACK_NO_TOKEN: + p = get_shadow_stack_page(0); + p += getpagesize() - sizeof(void *); + args.shadow_stack_pointer = (unsigned long long)p; + break; } memcpy(&args_ext.args, &args, sizeof(struct __clone_args)); @@ -102,7 +171,12 @@ static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode) if (pid == 0) { ksft_print_msg("I am the child, my PID is %d\n", getpid()); - _exit(EXIT_SUCCESS); + /* + * Use a raw syscall to ensure we don't get issues + * with manually specified shadow stack and exit handlers. + */ + syscall(__NR_exit, EXIT_SUCCESS); + ksft_print_msg("CHILD FAILED TO EXIT PID is %d\n", getpid()); } ksft_print_msg("I am the parent (%d). My child's pid is %d\n", @@ -184,6 +258,26 @@ 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; @@ -327,6 +421,50 @@ static const struct test tests[] = { .expected = -EINVAL, .test_mode = CLONE3_ARGS_NO_TEST, }, + { + .name = "Shadow stack on system with shadow stack", + .size = 0, + .expected = 0, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK, + .filter = no_shadow_stack, + }, + { + .name = "Shadow stack with misaligned address", + .flags = CLONE_VM, + .size = 0, + .expected = -EINVAL, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK_MISALIGNED, + .filter = no_shadow_stack, + }, + { + .name = "Shadow stack with normal memory", + .flags = CLONE_VM, + .size = 0, + .expected = -EFAULT, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK_NORMAL_MEMORY, + .filter = no_shadow_stack, + }, + { + .name = "Shadow stack with no token", + .flags = CLONE_VM, + .size = 0, + .expected = -EINVAL, + .e2big_valid = true, + .test_mode = CLONE3_ARGS_SHADOW_STACK_NO_TOKEN, + .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, + }, }; int main(int argc, char *argv[]) @@ -334,9 +472,12 @@ 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 39b5dcba663c30b9fc2542d9a0d2686105ce5761..26ff1554408a59af26bd708dc9c852210e370828 100644 --- a/tools/testing/selftests/clone3/clone3_selftests.h +++ b/tools/testing/selftests/clone3/clone3_selftests.h @@ -31,12 +31,75 @@ 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_pointer; +#ifndef CLONE_ARGS_SIZE_VER3 +#define CLONE_ARGS_SIZE_VER3 96 /* sizeof fourth published struct */ +#endif }; +/* + * For architectures with shadow stack support we need to be + * absolutely sure that the clone3() syscall will be inline and not a + * function call so we open code. + */ +#ifdef __x86_64__ +static pid_t __always_inline sys_clone3(struct __clone_args *args, size_t size) +{ + long ret; + register long _num __asm__ ("rax") = __NR_clone3; + register long _args __asm__ ("rdi") = (long)(args); + register long _size __asm__ ("rsi") = (long)(size); + + __asm__ volatile ( + "syscall\n" + : "=a"(ret) + : "r"(_args), "r"(_size), + "0"(_num) + : "rcx", "r11", "memory", "cc" + ); + + if (ret < 0) { + errno = -ret; + return -1; + } + + return ret; +} +#elif defined(__aarch64__) +static pid_t __always_inline sys_clone3(struct __clone_args *args, size_t size) +{ + register long _num __asm__ ("x8") = __NR_clone3; + register long _args __asm__ ("x0") = (long)(args); + register long _size __asm__ ("x1") = (long)(size); + register long arg2 __asm__ ("x2") = 0; + register long arg3 __asm__ ("x3") = 0; + register long arg4 __asm__ ("x4") = 0; + + __asm__ volatile ( + "svc #0\n" + : "=r"(_args) + : "r"(_args), "r"(_size), + "r"(_num), "r"(arg2), + "r"(arg3), "r"(arg4) + : "memory", "cc" + ); + + if ((int)_args < 0) { + errno = -((int)_args); + return -1; + } + + return _args; +} +#else static pid_t sys_clone3(struct __clone_args *args, size_t size) { return syscall(__NR_clone3, args, size); } +#endif static inline void test_clone3_supported(void) {