From patchwork Wed Jan 8 10:32:36 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930507 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C27B31F892F; Wed, 8 Jan 2025 10:34:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332455; cv=none; b=g9xQ/h0WPBLoWTK5vp4s9L6lgna5FW7RRTqm9kVW1YKd2V5UMqpGmUkBQZh8IJ5R0K7sFUM2ynePDoS1Rjno2tpzzfaZ12kurAX+Hlwkxc/tDmQyEKQ/JdNCRPsxRykN1pQkuMiaKWopCBzrJrym6r5hpA3A+VT4cwOlZzTC2Jc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332455; c=relaxed/simple; bh=OlG7m9fSOi1O2e5SLcYG2ohWiI4jTmn4LzEUJCirIlo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IDbUNI5UTGFpaV7OOOOdIQXGQEkcw2CgWo96AgJALX89bw0/zcfwA3jCwXBlyx3CMCqB/Am+pc6xF8xS479/+OurlXXQAkuvA5R2+Lx7xVX/LLOxCSiDvAxN2ubwygIBzV96RpKYEDAiwUS04nOHh1AMA9Wx45Yn+qYJ/zKp110= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 493AE1692; Wed, 8 Jan 2025 02:34:41 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2F10E3F673; Wed, 8 Jan 2025 02:34:10 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 01/15] mm: Introduce kpkeys Date: Wed, 8 Jan 2025 10:32:36 +0000 Message-ID: <20250108103250.3188419-2-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 kpkeys is a simple framework to enable the use of protection keys (pkeys) to harden the kernel itself. This patch introduces the basic API in : a couple of functions to set and restore the pkey register and a macro to define guard objects. kpkeys introduces a new concept on top of pkeys: the kpkeys level. Each level is associated to a set of permissions for the pkeys managed by the kpkeys framework. kpkeys_set_level(lvl) sets those permissions according to lvl, and returns the original pkey register, to be later restored by kpkeys_restore_pkey_reg(). To start with, only KPKEYS_LVL_DEFAULT is available, which is meant to grant RW access to KPKEYS_PKEY_DEFAULT (i.e. all memory since this is the only available pkey for now). Because each architecture implementing pkeys uses a different representation for the pkey register, and may reserve certain pkeys for specific uses, support for kpkeys must be explicitly indicated by selecting ARCH_HAS_KPKEYS and defining the following functions in , in addition to the macros provided in : - arch_kpkeys_set_level() - arch_kpkeys_restore_pkey_reg() - arch_kpkeys_enabled() Signed-off-by: Kevin Brodsky --- include/asm-generic/kpkeys.h | 9 +++++ include/linux/kpkeys.h | 66 ++++++++++++++++++++++++++++++++++++ mm/Kconfig | 2 ++ 3 files changed, 77 insertions(+) create mode 100644 include/asm-generic/kpkeys.h create mode 100644 include/linux/kpkeys.h diff --git a/include/asm-generic/kpkeys.h b/include/asm-generic/kpkeys.h new file mode 100644 index 000000000000..3404ce249757 --- /dev/null +++ b/include/asm-generic/kpkeys.h @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_GENERIC_KPKEYS_H +#define __ASM_GENERIC_KPKEYS_H + +#ifndef KPKEYS_PKEY_DEFAULT +#define KPKEYS_PKEY_DEFAULT 0 +#endif + +#endif /* __ASM_GENERIC_KPKEYS_H */ diff --git a/include/linux/kpkeys.h b/include/linux/kpkeys.h new file mode 100644 index 000000000000..70e44b0db150 --- /dev/null +++ b/include/linux/kpkeys.h @@ -0,0 +1,66 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef _LINUX_KPKEYS_H +#define _LINUX_KPKEYS_H + +#include +#include + +#define KPKEYS_LVL_DEFAULT 0 + +#define KPKEYS_LVL_MIN KPKEYS_LVL_DEFAULT +#define KPKEYS_LVL_MAX KPKEYS_LVL_DEFAULT + +#define KPKEYS_GUARD(_name, set_level, restore_pkey_reg) \ + __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ + DEFINE_CLASS(_name, u64, \ + restore_pkey_reg, set_level, void); \ + static inline void *class_##_name##_lock_ptr(u64 *_T) \ + { return _T; } + +#ifdef CONFIG_ARCH_HAS_KPKEYS + +#include + +/** + * kpkeys_set_level() - switch kpkeys level + * @level: the level to switch to + * + * Switches the kpkeys level to the specified value. @level must be a + * compile-time constant. The arch-specific pkey register will be updated + * accordingly, and the original value returned. + * + * Return: the original pkey register value. + */ +static inline u64 kpkeys_set_level(int level) +{ + BUILD_BUG_ON_MSG(!__builtin_constant_p(level), + "kpkeys_set_level() only takes constant levels"); + BUILD_BUG_ON_MSG(level < KPKEYS_LVL_MIN || level > KPKEYS_LVL_MAX, + "Invalid level passed to kpkeys_set_level()"); + + return arch_kpkeys_set_level(level); +} + +/** + * kpkeys_restore_pkey_reg() - restores a pkey register value + * @pkey_reg: the pkey register value to restore + * + * This function is meant to be passed the value returned by kpkeys_set_level(), + * in order to restore the pkey register to its original value (thus restoring + * the original kpkeys level). + */ +static inline void kpkeys_restore_pkey_reg(u64 pkey_reg) +{ + arch_kpkeys_restore_pkey_reg(pkey_reg); +} + +#else /* CONFIG_ARCH_HAS_KPKEYS */ + +static inline bool arch_kpkeys_enabled(void) +{ + return false; +} + +#endif /* CONFIG_ARCH_HAS_KPKEYS */ + +#endif /* _LINUX_KPKEYS_H */ diff --git a/mm/Kconfig b/mm/Kconfig index 1b501db06417..71edc478f111 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1147,6 +1147,8 @@ config ARCH_USES_HIGH_VMA_FLAGS bool config ARCH_HAS_PKEYS bool +config ARCH_HAS_KPKEYS + bool config ARCH_USES_PG_ARCH_2 bool From patchwork Wed Jan 8 10:32:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930508 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B29F51F8AFA; Wed, 8 Jan 2025 10:34:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332458; cv=none; b=QjZKwqBExFtmseavFkSx8DQAKKC4e9bEk3mwaxvg0am1oikiAmkY0lBltfpThjNk7G+eXPhxynAUYc5kcsOt0ZiSZrHMzDjC8z3G98k+mvlAOIW1B+6Uvb1WhCCtxu953KeL9uJjy34/K4dJTmqBIxGjEZZ98Hz5eF/rV0/y8mc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332458; c=relaxed/simple; bh=4aDjkHibEaVadfQGPlSSmLSpJv3EcwnykRxixv3rl/8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LcHm6IpJ1nRcOSHzyYu5XZuSQvFHs5M8qkbMT/hQ8TybNfr9EjC21KkfOwyCYTm/VUN3P2TjNCA0xTIv7RjIPqH0Exgbdhu80hEIQjL3kxEtp+GLUccYDm3JMy8iMH7Vo6BjupXgTt8tYw+HC41zUOPkKg01QS4IFj6WAXpzenI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 64BC9176C; Wed, 8 Jan 2025 02:34:44 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4A8783F673; Wed, 8 Jan 2025 02:34:13 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 02/15] set_memory: Introduce set_memory_pkey() stub Date: Wed, 8 Jan 2025 10:32:37 +0000 Message-ID: <20250108103250.3188419-3-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Introduce a new function, set_memory_pkey(), which sets the protection key (pkey) of pages in the specified linear mapping range. Architectures implementing kernel pkeys (kpkeys) must provide a suitable implementation; an empty stub is added as fallback. Signed-off-by: Kevin Brodsky --- include/linux/set_memory.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h index 3030d9245f5a..7b3a8bfde3c6 100644 --- a/include/linux/set_memory.h +++ b/include/linux/set_memory.h @@ -84,4 +84,11 @@ static inline int set_memory_decrypted(unsigned long addr, int numpages) } #endif /* CONFIG_ARCH_HAS_MEM_ENCRYPT */ +#ifndef CONFIG_ARCH_HAS_KPKEYS +static inline int set_memory_pkey(unsigned long addr, int numpages, int pkey) +{ + return 0; +} +#endif + #endif /* _LINUX_SET_MEMORY_H_ */ From patchwork Wed Jan 8 10:32:38 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930509 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id DAB641F8F0A; Wed, 8 Jan 2025 10:34:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332461; cv=none; b=CIHfocEU1WzmOCuLu3FrR42Aepxna17XEXrJQZ+UfDPg9j4B7PMvRjpL1lUH7V6c33VK/DREQRtQW8uApaux781mwsKvxp3Oa2iIUMTDq4YhqoGGisdGozkmFBq8U2A8KcYpZr4VYgD2sRnqHhvVCpHVJjwtKQ+c9mQFZagGMqQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332461; c=relaxed/simple; bh=vcEt5eafGosIZ+dsOCb4fbjRvoNGgfre5CLs6VP46aM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hbz7Bwp0p88iILlmrH0r9W9AEIBB1/JeYXF1Ss5yizcayQl4mcbBquUwCYRtSfQJcxORUCFuVRK3SdF+/lQiRCT6ksD46nKvVXPWIUfzABWtS4su9pqXwJB+Zsp5MSLQmwI2GJtvaO9uip/CAe0AmfaT2iSMuNR7Q/jeiR90Ebw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 802DA1BB0; Wed, 8 Jan 2025 02:34:47 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 661263F673; Wed, 8 Jan 2025 02:34:16 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 03/15] arm64: mm: Enable overlays for all EL1 indirect permissions Date: Wed, 8 Jan 2025 10:32:38 +0000 Message-ID: <20250108103250.3188419-4-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In preparation of using POE inside the kernel, enable "Overlay applied" for all stage 1 base permissions in PIR_EL1. This ensures that the permissions set in POR_EL1 affect all kernel mappings. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/pgtable-prot.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h index a95f1f77bb39..7c0c30460900 100644 --- a/arch/arm64/include/asm/pgtable-prot.h +++ b/arch/arm64/include/asm/pgtable-prot.h @@ -181,13 +181,13 @@ static inline bool __pure lpa2_is_enabled(void) PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS), PIE_NONE_O) | \ PIRx_ELx_PERM(pte_pi_index(_PAGE_GCS_RO), PIE_NONE_O) | \ PIRx_ELx_PERM(pte_pi_index(_PAGE_EXECONLY), PIE_NONE_O) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY_EXEC), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RW) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED), PIE_RW) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_ROX), PIE_RX) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_EXEC), PIE_RWX) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_RO), PIE_R) | \ - PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL), PIE_RW)) + PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY_EXEC), PIE_R_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED_EXEC), PIE_RW_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_READONLY), PIE_R_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_SHARED), PIE_RW_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_ROX), PIE_RX_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_EXEC), PIE_RWX_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL_RO), PIE_R_O) | \ + PIRx_ELx_PERM(pte_pi_index(_PAGE_KERNEL), PIE_RW_O)) #endif /* __ASM_PGTABLE_PROT_H */ From patchwork Wed Jan 8 10:32:39 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930510 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 00ADA1F940A; Wed, 8 Jan 2025 10:34:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332464; cv=none; b=EX0+GKI6womm2gXJKL55qx24tadIhS3xtCk+4O/FeV3CsrUnQim5Zd/m0l5/bGYpmP44d07tIDNdaLlKRT0tmjJc9eA9p3xEIuFuw4fs1hf8aTBVcRGH5gQDM0nC6JwTuIMqgyTfp3ZOWC1nvm6CS8e/NNXc8ORDUW2+YInyL9o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332464; c=relaxed/simple; bh=cm8of8N6CF+F4QHGa2huIXKOUQPLLZzMmFFRMoMuJFM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=t7KFTGlDh7bXQS/Oh77j0gWY26UBpcB4SganJXa8ohQdW/bXT6hrhgdWJrYyQTN2XkqfVuHjg9jamMAJGZFj7EP5xDbo1hfVyqNNQIG0Ej7QHTriWM/QMISegeajl+q3YSczmIEFhyvJCTmaYPHW6WbeIWXEx5ZvTZh3yQ0auCQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9C05C1BC0; Wed, 8 Jan 2025 02:34:50 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 81ED43F673; Wed, 8 Jan 2025 02:34:19 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 04/15] arm64: Introduce por_set_pkey_perms() helper Date: Wed, 8 Jan 2025 10:32:39 +0000 Message-ID: <20250108103250.3188419-5-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Introduce a helper that sets the permissions of a given pkey (POIndex) in the POR_ELx format, and make use of it in arch_set_user_pkey_access(). Also ensure that is included in asm/por.h to provide the POE_* definitions. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/por.h | 9 +++++++++ arch/arm64/mm/mmu.c | 28 ++++++++++------------------ 2 files changed, 19 insertions(+), 18 deletions(-) diff --git a/arch/arm64/include/asm/por.h b/arch/arm64/include/asm/por.h index e06e9f473675..7f0d73980cce 100644 --- a/arch/arm64/include/asm/por.h +++ b/arch/arm64/include/asm/por.h @@ -6,6 +6,8 @@ #ifndef _ASM_ARM64_POR_H #define _ASM_ARM64_POR_H +#include + #define POR_BITS_PER_PKEY 4 #define POR_ELx_IDX(por_elx, idx) (((por_elx) >> ((idx) * POR_BITS_PER_PKEY)) & 0xf) @@ -30,4 +32,11 @@ static inline bool por_elx_allows_exec(u64 por, u8 pkey) return perm & POE_X; } +static inline u64 por_set_pkey_perms(u64 por, u8 pkey, u64 perms) +{ + u64 shift = pkey * POR_BITS_PER_PKEY; + + return (por & ~(POE_MASK << shift)) | (perms << shift); +} + #endif /* _ASM_ARM64_POR_H */ diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index e2739b69e11b..20e0390ee382 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1554,9 +1554,8 @@ void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp) #ifdef CONFIG_ARCH_HAS_PKEYS int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val) { - u64 new_por = POE_RXW; - u64 old_por; - u64 pkey_shift; + u64 new_perms; + u64 por; if (!system_supports_poe()) return -ENOSPC; @@ -1570,26 +1569,19 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long i return -EINVAL; /* Set the bits we need in POR: */ - new_por = POE_RXW; + new_perms = POE_RXW; if (init_val & PKEY_DISABLE_WRITE) - new_por &= ~POE_W; + new_perms &= ~POE_W; if (init_val & PKEY_DISABLE_ACCESS) - new_por &= ~POE_RW; + new_perms &= ~POE_RW; if (init_val & PKEY_DISABLE_READ) - new_por &= ~POE_R; + new_perms &= ~POE_R; if (init_val & PKEY_DISABLE_EXECUTE) - new_por &= ~POE_X; + new_perms &= ~POE_X; - /* Shift the bits in to the correct place in POR for pkey: */ - pkey_shift = pkey * POR_BITS_PER_PKEY; - new_por <<= pkey_shift; - - /* Get old POR and mask off any old bits in place: */ - old_por = read_sysreg_s(SYS_POR_EL0); - old_por &= ~(POE_MASK << pkey_shift); - - /* Write old part along with new part: */ - write_sysreg_s(old_por | new_por, SYS_POR_EL0); + por = read_sysreg_s(SYS_POR_EL0); + por = por_set_pkey_perms(por, pkey, new_perms); + write_sysreg_s(por, SYS_POR_EL0); return 0; } From patchwork Wed Jan 8 10:32:40 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930511 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 160AB1F9A9B; Wed, 8 Jan 2025 10:34:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332467; cv=none; b=NuAhgzZXZ/MDIbsevh43njnxf9gsD1dwR45Q6C09QzGCRocZn3uHhzUxXmF2y72s/F7hu7X6sknzxOKbcdTjmwGbXKz/OaAhKQ8ze76yR7UVQYZw5kTFQuPdeq2ruiEGY5wbB2IU4cxHD9wQwZ/EqHBF5piGoRJmfwROhMBRXlo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332467; c=relaxed/simple; bh=ADi3c0PRpU2JemlHu/u0oUZ4vDQkss9aFXz31FTjnBw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LscsUKHaAlzPEOckRzWedYg3vhjAD8I+hEMmj5JTHf1Vl3E4344R+wGLFWsfXTdcq5uGGjcDFAWwCr/vmyxZxeOSGywdG8N/WYBsEXeMr+QHkKsd6UA4CfQ4CUHpJWMKqjF/OYQVa8TGmE09h25o+Yc0hQBc2Vdu1NieJUJEHvo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B740513D5; Wed, 8 Jan 2025 02:34:53 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D3B93F673; Wed, 8 Jan 2025 02:34:22 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 05/15] arm64: Implement asm/kpkeys.h using POE Date: Wed, 8 Jan 2025 10:32:40 +0000 Message-ID: <20250108103250.3188419-6-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Implement the kpkeys interface if CONFIG_ARM64_POE is enabled. The permissions for KPKEYS_PKEY_DEFAULT (pkey 0) are set to RWX as this pkey is also used for code mappings. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/kpkeys.h | 43 +++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 arch/arm64/include/asm/kpkeys.h diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h new file mode 100644 index 000000000000..e17f6df41873 --- /dev/null +++ b/arch/arm64/include/asm/kpkeys.h @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +#ifndef __ASM_KPKEYS_H +#define __ASM_KPKEYS_H + +#include +#include +#include + +#include + +static inline bool arch_kpkeys_enabled(void) +{ + return system_supports_poe(); +} + +#ifdef CONFIG_ARM64_POE + +static inline u64 por_set_kpkeys_level(u64 por, int level) +{ + por = por_set_pkey_perms(por, KPKEYS_PKEY_DEFAULT, POE_RXW); + + return por; +} + +static inline int arch_kpkeys_set_level(int level) +{ + u64 prev_por = read_sysreg_s(SYS_POR_EL1); + + write_sysreg_s(por_set_kpkeys_level(prev_por, level), SYS_POR_EL1); + isb(); + + return prev_por; +} + +static inline void arch_kpkeys_restore_pkey_reg(u64 pkey_reg) +{ + write_sysreg_s(pkey_reg, SYS_POR_EL1); + isb(); +} + +#endif /* CONFIG_ARM64_POE */ + +#endif /* __ASM_KPKEYS_H */ From patchwork Wed Jan 8 10:32:41 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930512 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 39B5A1F9ED4; Wed, 8 Jan 2025 10:34:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332470; cv=none; b=BJwl2jgem2eLZoAk1snJlAOMVsqfydretjNbQuaLuVL+8IjKDHIfSwRUuWoZbuhDbtTwBskSjIAnJeg0uo7X/3kK5RdBejFlwG6x+uAAVreqkjoQ9fCVBO0t6Vp4Z7Sw149QA+nXPc7U7/4vCx3zmauDvNO3R/XOWUBlhrRDYm4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332470; c=relaxed/simple; bh=PzynSjr+h3L6Ghu22EZN4B7SeJ4UK2N5JOo/45g3ElM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Bdh3p1Ooow60MCrKZ54L/1BCZ/cwKT/o1Iu3w9bJebMpl3nDxbBMlAil9jCYNTjT4FRHIJzmDnNWsCm9JYXcY1Tgmxy9HzCXbAPIJXkNTbFi+Jty0W4Z+/BwiUQylhC2dWqSm8pkTQxjBEDE5r+2dFZj221K9y+GlFnqHxVrhQ4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D25A61692; Wed, 8 Jan 2025 02:34:56 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B86F03F673; Wed, 8 Jan 2025 02:34:25 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 06/15] arm64: set_memory: Implement set_memory_pkey() Date: Wed, 8 Jan 2025 10:32:41 +0000 Message-ID: <20250108103250.3188419-7-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Implement set_memory_pkey() using POE if supported. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/set_memory.h | 4 ++++ arch/arm64/mm/pageattr.c | 21 +++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h index 90f61b17275e..b6cd6de34abf 100644 --- a/arch/arm64/include/asm/set_memory.h +++ b/arch/arm64/include/asm/set_memory.h @@ -19,4 +19,8 @@ bool kernel_page_present(struct page *page); int set_memory_encrypted(unsigned long addr, int numpages); int set_memory_decrypted(unsigned long addr, int numpages); +#ifdef CONFIG_ARCH_HAS_KPKEYS +int set_memory_pkey(unsigned long addr, int numpages, int pkey); +#endif + #endif /* _ASM_ARM64_SET_MEMORY_H */ diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 39fd1f7ff02a..3b8fec532b18 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -292,6 +292,27 @@ int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool valid) return set_memory_valid(addr, nr, valid); } +#ifdef CONFIG_ARCH_HAS_KPKEYS +int set_memory_pkey(unsigned long addr, int numpages, int pkey) +{ + unsigned long set_prot = 0; + + if (!system_supports_poe()) + return 0; + + if (!__is_lm_address(addr)) + return -EINVAL; + + set_prot |= pkey & BIT(0) ? PTE_PO_IDX_0 : 0; + set_prot |= pkey & BIT(1) ? PTE_PO_IDX_1 : 0; + set_prot |= pkey & BIT(2) ? PTE_PO_IDX_2 : 0; + + return __change_memory_common(addr, PAGE_SIZE * numpages, + __pgprot(set_prot), + __pgprot(PTE_PO_IDX_MASK)); +} +#endif + #ifdef CONFIG_DEBUG_PAGEALLOC /* * This is - apart from the return value - doing the same From patchwork Wed Jan 8 10:32:42 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930513 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3DFEB1FA151; Wed, 8 Jan 2025 10:34:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332473; cv=none; b=RI1F8afOS2mdy0aIJaLQWN8devnEU1eLos+oAAwVhRD9jfz0MS+3L/hOvb19ywMxssplPDQNFbCwVTqFIjPHm29MM264ah1dE9xyjA3ZUaM8kStN/deztZP4ORukGsNKWOFem+u6IY+CR3wNVpW9R9lv3JykZe7r6Orne/lLUsM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332473; c=relaxed/simple; bh=iJDCAhAMSiiHaVYlO46euqQqUTkvuOLUFxoslTq2+jU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ahDjycDzsyL90VdZH+E2QpfEXWwdSajS9/Xw9YrGw9rq4XASR1iW16aBdYyyjdOet1JojiZsaGNtwAtAVXvKCKo0SeLEGr+t4AnDJzw92pRbcISQ243rcvFj6Mx9gJHchLdMt51cPhT0+yJKuw/wUigY+lFBUUnqMt4kEZZdv5I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EDCD3176C; Wed, 8 Jan 2025 02:34:59 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D3E5C3F673; Wed, 8 Jan 2025 02:34:28 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 07/15] arm64: Enable kpkeys Date: Wed, 8 Jan 2025 10:32:42 +0000 Message-ID: <20250108103250.3188419-8-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This is the final step to enable kpkeys on arm64. We enable POE at EL1 by setting TCR2_EL1.POE, and initialise POR_EL1 so that it enables access to the default pkey/POIndex (default kpkeys level). An ISB is added so that POE restrictions are enforced immediately. Having done this, we can now select ARCH_HAS_KPKEYS if ARM64_POE is enabled. Signed-off-by: Kevin Brodsky --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/cpufeature.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 8bd31e754e79..688ffd9bf503 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2184,6 +2184,7 @@ config ARM64_POE def_bool y select ARCH_USES_HIGH_VMA_FLAGS select ARCH_HAS_PKEYS + select ARCH_HAS_KPKEYS help The Permission Overlay Extension is used to implement Memory Protection Keys. Memory Protection Keys provides a mechanism for diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 829c9f6d326a..94735c91b980 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -76,6 +76,7 @@ #include #include #include +#include #include #include @@ -2387,8 +2388,10 @@ static void cpu_enable_mops(const struct arm64_cpu_capabilities *__unused) #ifdef CONFIG_ARM64_POE static void cpu_enable_poe(const struct arm64_cpu_capabilities *__unused) { - sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE); + write_sysreg_s(por_set_kpkeys_level(0, KPKEYS_LVL_DEFAULT), SYS_POR_EL1); + sysreg_clear_set(REG_TCR2_EL1, 0, TCR2_EL1_E0POE | TCR2_EL1_POE); sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_E0POE); + isb(); } #endif From patchwork Wed Jan 8 10:32:43 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930514 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6AF881FA262; Wed, 8 Jan 2025 10:34:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332477; cv=none; b=SX08c5F2Qha49EsQkpLG3SmQMgdkbzfcOG+VHNJHPx69MGdtuFsKLn3yDPgpgVQjs0zioZpM2To6xR8y/I0C64EaELOCbwK1/8Q0+SPuLxbVvECsz2Bfp5N4Nn6iOzokVstas8KVTfJEVdhXPs2MCnoWX5SY4Cn6wNdIiBgq+lA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332477; c=relaxed/simple; bh=66AKNC3DffL+1lyXAGbUZ7CZOqicvaecfbLmh4Pn+pU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IhU60UVu2fhKt75ZDjGJDym88XEJYnrXGIKdGnCETcOJamqHDg1I9fO457VWXKU6u7FpzGGb2o0VvGR15cxGkVoGtyTgCWURGfTpPZdk8+46CEkgpoxniufZQhKFW1+iiThS4Tm3MOMp5cswe7/dpvEkaolgKlRSrY8OahYTz8Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 157A713D5; Wed, 8 Jan 2025 02:35:03 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EF8143F673; Wed, 8 Jan 2025 02:34:31 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 08/15] mm: Introduce kernel_pgtables_set_pkey() Date: Wed, 8 Jan 2025 10:32:43 +0000 Message-ID: <20250108103250.3188419-9-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 kernel_pgtables_set_pkey() allows setting the pkey of all page table pages in swapper_pg_dir, recursively. This will be needed by kpkeys_hardened_pgtables, as it relies on all PTPs being mapped with a non-default pkey. Those initial kernel page tables cannot practically be assigned a non-default pkey right when they are allocated, so mutating them during (early) boot is required. Signed-off-by: Kevin Brodsky --- include/linux/mm.h | 2 + mm/memory.c | 137 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 139 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index f2a144c4734d..453a26bcad1a 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4239,4 +4239,6 @@ int arch_get_shadow_stack_status(struct task_struct *t, unsigned long __user *st int arch_set_shadow_stack_status(struct task_struct *t, unsigned long status); int arch_lock_shadow_stack_status(struct task_struct *t, unsigned long status); +int kernel_pgtables_set_pkey(int pkey); + #endif /* _LINUX_MM_H */ diff --git a/mm/memory.c b/mm/memory.c index e3f34a179f4a..fbc4ac25d19b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -77,6 +77,8 @@ #include #include #include +#include +#include #include @@ -7129,3 +7131,138 @@ void vma_pgtable_walk_end(struct vm_area_struct *vma) if (is_vm_hugetlb_page(vma)) hugetlb_vma_unlock_read(vma); } + +static int set_page_pkey(void *p, int pkey) +{ + unsigned long addr = (unsigned long)p; + + /* + * swapper_pg_dir itself will be made read-only by mark_rodata_ro() + * so there is no point in changing its pkey. + */ + if (p == swapper_pg_dir) + return 0; + + return set_memory_pkey(addr, 1, pkey); +} + +static int set_pkey_pte(pmd_t *pmd, int pkey) +{ + pte_t *pte; + int err; + + pte = pte_offset_kernel(pmd, 0); + err = set_page_pkey(pte, pkey); + + return err; +} + +static int set_pkey_pmd(pud_t *pud, int pkey) +{ + pmd_t *pmd; + int i, err = 0; + + pmd = pmd_offset(pud, 0); + + err = set_page_pkey(pmd, pkey); + if (err) + return err; + + for (i = 0; i < PTRS_PER_PMD; i++) { + if (pmd_none(pmd[i]) || pmd_bad(pmd[i]) || pmd_leaf(pmd[i])) + continue; + err = set_pkey_pte(&pmd[i], pkey); + if (err) + break; + } + + return err; +} + +static int set_pkey_pud(p4d_t *p4d, int pkey) +{ + pud_t *pud; + int i, err = 0; + + if (mm_pmd_folded(&init_mm)) + return set_pkey_pmd((pud_t *)p4d, pkey); + + pud = pud_offset(p4d, 0); + + err = set_page_pkey(pud, pkey); + if (err) + return err; + + for (i = 0; i < PTRS_PER_PUD; i++) { + if (pud_none(pud[i]) || pud_bad(pud[i]) || pud_leaf(pud[i])) + continue; + err = set_pkey_pmd(&pud[i], pkey); + if (err) + break; + } + + return err; +} + +static int set_pkey_p4d(pgd_t *pgd, int pkey) +{ + p4d_t *p4d; + int i, err = 0; + + if (mm_pud_folded(&init_mm)) + return set_pkey_pud((p4d_t *)pgd, pkey); + + p4d = p4d_offset(pgd, 0); + + err = set_page_pkey(p4d, pkey); + if (err) + return err; + + for (i = 0; i < PTRS_PER_P4D; i++) { + if (p4d_none(p4d[i]) || p4d_bad(p4d[i]) || p4d_leaf(p4d[i])) + continue; + err = set_pkey_pud(&p4d[i], pkey); + if (err) + break; + } + + return err; +} + +/** + * kernel_pgtables_set_pkey - set pkey for all kernel page table pages + * @pkey: pkey to set the page table pages to + * + * Walks swapper_pg_dir setting the protection key of every page table page (at + * all levels) to @pkey. swapper_pg_dir itself is left untouched as it is + * expected to be mapped read-only by mark_rodata_ro(). + * + * No-op if the architecture does not support kpkeys. + */ +int kernel_pgtables_set_pkey(int pkey) +{ + pgd_t *pgd = swapper_pg_dir; + int i, err = 0; + + if (!arch_kpkeys_enabled()) + return 0; + + spin_lock(&init_mm.page_table_lock); + + if (mm_p4d_folded(&init_mm)) { + err = set_pkey_p4d(pgd, pkey); + goto out; + } + + for (i = 0; i < PTRS_PER_PGD; i++) { + if (pgd_none(pgd[i]) || pgd_bad(pgd[i]) || pgd_leaf(pgd[i])) + continue; + err = set_pkey_p4d(&pgd[i], pkey); + if (err) + break; + } + +out: + spin_unlock(&init_mm.page_table_lock); + return err; +} From patchwork Wed Jan 8 10:32:44 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930515 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9A4B71FA8D8; Wed, 8 Jan 2025 10:34:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332480; cv=none; b=bx/KJuDwRrbDzdOp1SULtZ7SyeiM+WgwCb1F8z0pcjZeyr4g+lBfZnGfGFU33noYxo1JCLZswfadjVwiOIgXLXPhtbVYTENMgo2lEuUh6QhK27qC8TY/X7rHGHmqVBm0+J5A+S7qxhSCtZYjxnA7M8PrPcyZCwYupmtx7P2e43o= ARC-Message-Signature: i=1; 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Wed, 8 Jan 2025 02:34:34 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 09/15] mm: Introduce kpkeys_hardened_pgtables Date: Wed, 8 Jan 2025 10:32:44 +0000 Message-ID: <20250108103250.3188419-10-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 kpkeys_hardened_pgtables is a hardening feature based on kpkeys. It aims to prevent the corruption of page tables by: 1. mapping all page table pages, both kernel and user, with a privileged pkey (KPKEYS_PKEY_PGTABLES), and 2. granting write access to that pkey only when running at a higher kpkeys level (KPKEYS_LVL_PGTABLES). The feature is exposed as CONFIG_KPKEYS_HARDENED_PGTABLES; it requires explicit architecture opt-in by selecting ARCH_HAS_KPKEYS_HARDENED_PGTABLES, since much of the page table handling is arch-specific. This patch introduces an API to modify the PTPs' pkey and switch kpkeys level using a guard object. Because this API is going to be called from low-level pgtable helpers (setters, allocators), it must be inactive on boot and explicitly switched on if and when kpkeys become available. A static key is used for that purpose; it is the responsibility of each architecture supporting kpkeys_hardened_pgtables to call kpkeys_hardened_pgtables_enable() as early as possible to switch on that static key. The initial kernel page tables are also walked to set their pkey, since they have already been allocated at that point. The definition of the kpkeys_hardened_pgtables guard class does not use the static key on the restore path to avoid mismatched set/restore pairs. Indeed, enabling the static key itself involves modifying page tables, and it is thus possible that the guard object is created when the static key appears as false, and destroyed when it appears as true. To avoid this situation, we reserve an invalid value for the pkey register and use it to disable the restore path. Signed-off-by: Kevin Brodsky --- include/asm-generic/kpkeys.h | 12 +++++++++ include/linux/kpkeys.h | 48 ++++++++++++++++++++++++++++++++++- mm/Kconfig | 3 +++ mm/Makefile | 1 + mm/kpkeys_hardened_pgtables.c | 44 ++++++++++++++++++++++++++++++++ security/Kconfig.hardening | 12 +++++++++ 6 files changed, 119 insertions(+), 1 deletion(-) create mode 100644 mm/kpkeys_hardened_pgtables.c diff --git a/include/asm-generic/kpkeys.h b/include/asm-generic/kpkeys.h index 3404ce249757..cec92334a9f3 100644 --- a/include/asm-generic/kpkeys.h +++ b/include/asm-generic/kpkeys.h @@ -2,8 +2,20 @@ #ifndef __ASM_GENERIC_KPKEYS_H #define __ASM_GENERIC_KPKEYS_H +#ifndef KPKEYS_PKEY_PGTABLES +#define KPKEYS_PKEY_PGTABLES 1 +#endif + #ifndef KPKEYS_PKEY_DEFAULT #define KPKEYS_PKEY_DEFAULT 0 #endif +/* + * Represents a pkey register value that cannot be used, typically disabling + * access to all keys. + */ +#ifndef KPKEYS_PKEY_REG_INVAL +#define KPKEYS_PKEY_REG_INVAL 0 +#endif + #endif /* __ASM_GENERIC_KPKEYS_H */ diff --git a/include/linux/kpkeys.h b/include/linux/kpkeys.h index 70e44b0db150..587cf8b4bd33 100644 --- a/include/linux/kpkeys.h +++ b/include/linux/kpkeys.h @@ -4,11 +4,13 @@ #include #include +#include #define KPKEYS_LVL_DEFAULT 0 +#define KPKEYS_LVL_PGTABLES 1 #define KPKEYS_LVL_MIN KPKEYS_LVL_DEFAULT -#define KPKEYS_LVL_MAX KPKEYS_LVL_DEFAULT +#define KPKEYS_LVL_MAX KPKEYS_LVL_PGTABLES #define KPKEYS_GUARD(_name, set_level, restore_pkey_reg) \ __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ @@ -63,4 +65,48 @@ static inline bool arch_kpkeys_enabled(void) #endif /* CONFIG_ARCH_HAS_KPKEYS */ +#ifdef CONFIG_KPKEYS_HARDENED_PGTABLES + +DECLARE_STATIC_KEY_FALSE(kpkeys_hardened_pgtables_enabled); + +/* + * Use guard(kpkeys_hardened_pgtables)() to temporarily grant write access + * to page tables. + */ +KPKEYS_GUARD(kpkeys_hardened_pgtables, + static_branch_unlikely(&kpkeys_hardened_pgtables_enabled) ? + kpkeys_set_level(KPKEYS_LVL_PGTABLES) : + KPKEYS_PKEY_REG_INVAL, + _T != KPKEYS_PKEY_REG_INVAL ? + kpkeys_restore_pkey_reg(_T) : + (void)0) + +int kpkeys_protect_pgtable_memory(struct folio *folio); +int kpkeys_unprotect_pgtable_memory(struct folio *folio); + +/* + * Enables kpkeys_hardened_pgtables and switches existing kernel page tables to + * a privileged pkey (KPKEYS_PKEY_PGTABLES). + * + * Should be called as early as possible by architecture code, after (k)pkeys + * are initialised and before any user task is spawned. + */ +void kpkeys_hardened_pgtables_enable(void); + +#else /* CONFIG_KPKEYS_HARDENED_PGTABLES */ + +KPKEYS_GUARD(kpkeys_hardened_pgtables, 0, (void)_T) + +static inline int kpkeys_protect_pgtable_memory(struct folio *folio) +{ + return 0; +} +static inline int kpkeys_unprotect_pgtable_memory(struct folio *folio) +{ + return 0; +} +static inline void kpkeys_hardened_pgtables_enable(void) {} + +#endif /* CONFIG_KPKEYS_HARDENED_PGTABLES */ + #endif /* _LINUX_KPKEYS_H */ diff --git a/mm/Kconfig b/mm/Kconfig index 71edc478f111..2a8ebe780e64 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1149,6 +1149,9 @@ config ARCH_HAS_PKEYS bool config ARCH_HAS_KPKEYS bool +# ARCH_HAS_KPKEYS must be selected when selecting this option +config ARCH_HAS_KPKEYS_HARDENED_PGTABLES + bool config ARCH_USES_PG_ARCH_2 bool diff --git a/mm/Makefile b/mm/Makefile index 850386a67b3e..130691364172 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -147,3 +147,4 @@ obj-$(CONFIG_SHRINKER_DEBUG) += shrinker_debug.o obj-$(CONFIG_EXECMEM) += execmem.o obj-$(CONFIG_TMPFS_QUOTA) += shmem_quota.o obj-$(CONFIG_PT_RECLAIM) += pt_reclaim.o +obj-$(CONFIG_KPKEYS_HARDENED_PGTABLES) += kpkeys_hardened_pgtables.o diff --git a/mm/kpkeys_hardened_pgtables.c b/mm/kpkeys_hardened_pgtables.c new file mode 100644 index 000000000000..c6eb7fb6ae56 --- /dev/null +++ b/mm/kpkeys_hardened_pgtables.c @@ -0,0 +1,44 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +DEFINE_STATIC_KEY_FALSE(kpkeys_hardened_pgtables_enabled); + +int kpkeys_protect_pgtable_memory(struct folio *folio) +{ + unsigned long addr = (unsigned long)folio_address(folio); + unsigned int order = folio_order(folio); + int ret = 0; + + if (static_branch_unlikely(&kpkeys_hardened_pgtables_enabled)) + ret = set_memory_pkey(addr, 1 << order, KPKEYS_PKEY_PGTABLES); + + WARN_ON(ret); + return ret; +} + +int kpkeys_unprotect_pgtable_memory(struct folio *folio) +{ + unsigned long addr = (unsigned long)folio_address(folio); + unsigned int order = folio_order(folio); + int ret = 0; + + if (static_branch_unlikely(&kpkeys_hardened_pgtables_enabled)) + ret = set_memory_pkey(addr, 1 << order, KPKEYS_PKEY_DEFAULT); + + WARN_ON(ret); + return ret; +} + +void __init kpkeys_hardened_pgtables_enable(void) +{ + int ret; + + if (!arch_kpkeys_enabled()) + return; + + static_branch_enable(&kpkeys_hardened_pgtables_enabled); + ret = kernel_pgtables_set_pkey(KPKEYS_PKEY_PGTABLES); + WARN_ON(ret); +} diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index c9d5ca3d8d08..95f93f1d4055 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -300,6 +300,18 @@ config BUG_ON_DATA_CORRUPTION If unsure, say N. +config KPKEYS_HARDENED_PGTABLES + bool "Harden page tables using kernel pkeys" + depends on ARCH_HAS_KPKEYS_HARDENED_PGTABLES + help + This option makes all page tables mostly read-only by + allocating them with a non-default protection key (pkey) and + only enabling write access to that pkey in routines that are + expected to write to page table entries. + + This option has no effect if the system does not support + kernel pkeys. + endmenu config CC_HAS_RANDSTRUCT From patchwork Wed Jan 8 10:32:45 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930516 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 931501FA8F7; Wed, 8 Jan 2025 10:34:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332483; cv=none; b=ULRcigrdUlsOAvsyvomujsnlrF/DFzKy1tckHyDRPu8wU12q2KjFBTh9sU0uB6UJ797nhD8kpSkcktYZMvaSz329f9LC57HrFHEb3X+HaqLQapo5younk5oWuS+QYe2HLFhSR7Z/GFDYPXFYRkcQZROSZaX/dgdZsiqquRrKGGM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332483; c=relaxed/simple; bh=V7NBXEVq5k2syMALHZPsYhgC4AXMseqyJ8n/LS87KSI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VNiwZNUMR++c3EWhErE+aOCI9yEsXBg9kBTMSrUNrKLCw+kbuBV+W5JjMitrSFx7q+390WhifvRrs99eUkNX7LhNHB0+DDt28WJo4n5RC+kU/8wiPMlNANUY9kqTQrBU/i4TLB19TU3eB41j6iFsoetKtBogmhgWUy48tMC3/1Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4B350176C; Wed, 8 Jan 2025 02:35:09 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 31B3A3F673; Wed, 8 Jan 2025 02:34:38 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 10/15] mm: Allow __pagetable_ctor() to fail Date: Wed, 8 Jan 2025 10:32:45 +0000 Message-ID: <20250108103250.3188419-11-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In preparation for adding construction hooks (that may fail) to __pagetable_ctor(), make __pagetable_ctor() return a bool, propagate it to pagetable_*_ctor() and handle failure in the generic {pud,p4d,pgd}_alloc. Signed-off-by: Kevin Brodsky --- include/asm-generic/pgalloc.h | 15 ++++++++++++--- include/linux/mm.h | 21 ++++++++++----------- 2 files changed, 22 insertions(+), 14 deletions(-) diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h index 892ece4558a2..9962f7454d0c 100644 --- a/include/asm-generic/pgalloc.h +++ b/include/asm-generic/pgalloc.h @@ -173,7 +173,10 @@ static inline pud_t *__pud_alloc_one_noprof(struct mm_struct *mm, unsigned long if (!ptdesc) return NULL; - pagetable_pud_ctor(ptdesc); + if (!pagetable_pud_ctor(ptdesc)) { + pagetable_free(ptdesc); + return NULL; + } return ptdesc_address(ptdesc); } #define __pud_alloc_one(...) alloc_hooks(__pud_alloc_one_noprof(__VA_ARGS__)) @@ -227,7 +230,10 @@ static inline p4d_t *__p4d_alloc_one_noprof(struct mm_struct *mm, unsigned long if (!ptdesc) return NULL; - pagetable_p4d_ctor(ptdesc); + if (!pagetable_p4d_ctor(ptdesc)) { + pagetable_free(ptdesc); + return NULL; + } return ptdesc_address(ptdesc); } #define __p4d_alloc_one(...) alloc_hooks(__p4d_alloc_one_noprof(__VA_ARGS__)) @@ -271,7 +277,10 @@ static inline pgd_t *__pgd_alloc_noprof(struct mm_struct *mm, unsigned int order if (!ptdesc) return NULL; - pagetable_pgd_ctor(ptdesc); + if (!pagetable_pgd_ctor(ptdesc)) { + pagetable_free(ptdesc); + return NULL; + } return ptdesc_address(ptdesc); } #define __pgd_alloc(...) alloc_hooks(__pgd_alloc_noprof(__VA_ARGS__)) diff --git a/include/linux/mm.h b/include/linux/mm.h index 453a26bcad1a..e99040be477f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3076,12 +3076,13 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; } static inline void ptlock_free(struct ptdesc *ptdesc) {} #endif /* defined(CONFIG_SPLIT_PTE_PTLOCKS) */ -static inline void __pagetable_ctor(struct ptdesc *ptdesc) +static inline bool __pagetable_ctor(struct ptdesc *ptdesc) { struct folio *folio = ptdesc_folio(ptdesc); __folio_set_pgtable(folio); lruvec_stat_add_folio(folio, NR_PAGETABLE); + return true; } static inline void pagetable_dtor(struct ptdesc *ptdesc) @@ -3103,8 +3104,7 @@ static inline bool pagetable_pte_ctor(struct ptdesc *ptdesc) { if (!ptlock_init(ptdesc)) return false; - __pagetable_ctor(ptdesc); - return true; + return __pagetable_ctor(ptdesc); } pte_t *___pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp); @@ -3210,8 +3210,7 @@ static inline bool pagetable_pmd_ctor(struct ptdesc *ptdesc) if (!pmd_ptlock_init(ptdesc)) return false; ptdesc_pmd_pts_init(ptdesc); - __pagetable_ctor(ptdesc); - return true; + return __pagetable_ctor(ptdesc); } /* @@ -3233,19 +3232,19 @@ static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud) return ptl; } -static inline void pagetable_pud_ctor(struct ptdesc *ptdesc) +static inline bool pagetable_pud_ctor(struct ptdesc *ptdesc) { - __pagetable_ctor(ptdesc); + return __pagetable_ctor(ptdesc); } -static inline void pagetable_p4d_ctor(struct ptdesc *ptdesc) +static inline bool pagetable_p4d_ctor(struct ptdesc *ptdesc) { - __pagetable_ctor(ptdesc); + return __pagetable_ctor(ptdesc); } -static inline void pagetable_pgd_ctor(struct ptdesc *ptdesc) +static inline bool pagetable_pgd_ctor(struct ptdesc *ptdesc) { - __pagetable_ctor(ptdesc); + return __pagetable_ctor(ptdesc); } extern void __init pagecache_init(void); From patchwork Wed Jan 8 10:32:46 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930517 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id ABEFD1FBC8C; Wed, 8 Jan 2025 10:34:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332486; cv=none; b=nsnN+6DZB4HRf5SlLgWPBpyqvld8GkWbW6TAgbdWF3U2fqDR9kKJMt9ZS/66434stjFmkJs89xPWg3Zdl00CbvUdqa9W8/5rZPIzcc9dhNeCXIL5dz++HpMB+GjR4qQFiicJMrgKL/oGmp8Dz+7c6JWPpvKOt5B8Z+OYDIqMliI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332486; c=relaxed/simple; bh=d5k63jL9YybpyZQyvNS/bMNYby/r6OcT2A9wyicj9lY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZSyl3kNDAel9awAklzFhBLvRZaJs7VHMx9fEvvvruvu/Mw2TngdHLJ7JyGkTY0o7DkoiYcskYa1xlrZyaLuakCZETkkz/mk8uKmn+B46zMNbu++w9V7It6Hl8HAwVReTsueBwFfyB5dUFx7AkcRpdsQ/OdVE/eNCn7A7sam1DyY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 66B6713D5; Wed, 8 Jan 2025 02:35:12 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4CDC03F673; Wed, 8 Jan 2025 02:34:41 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 11/15] mm: Map page tables with privileged pkey Date: Wed, 8 Jan 2025 10:32:46 +0000 Message-ID: <20250108103250.3188419-12-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 If CONFIG_KPKEYS_HARDENED_PGTABLES is enabled, map allocated page table pages using a privileged pkey (KPKEYS_PKEY_PGTABLES), so that page tables can only be written under guard(kpkeys_hardened_pgtables). This patch is a no-op if CONFIG_KPKEYS_HARDENED_PGTABLES is disabled (default). Signed-off-by: Kevin Brodsky --- include/linux/mm.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index e99040be477f..714e1af91752 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -33,6 +33,7 @@ #include #include #include +#include struct mempolicy; struct anon_vma; @@ -3082,6 +3083,8 @@ static inline bool __pagetable_ctor(struct ptdesc *ptdesc) __folio_set_pgtable(folio); lruvec_stat_add_folio(folio, NR_PAGETABLE); + if (kpkeys_protect_pgtable_memory(folio)) + return false; return true; } @@ -3092,6 +3095,7 @@ static inline void pagetable_dtor(struct ptdesc *ptdesc) ptlock_free(ptdesc); __folio_clear_pgtable(folio); lruvec_stat_sub_folio(folio, NR_PAGETABLE); + kpkeys_unprotect_pgtable_memory(folio); } static inline void pagetable_dtor_free(struct ptdesc *ptdesc) From patchwork Wed Jan 8 10:32:47 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930518 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F35851F8AE3; Wed, 8 Jan 2025 10:34:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332489; cv=none; b=uVG5HK6LBa68goOkuQREQ17KMT03JQjORx8K355I/lelYPK7msrA28ZjLV/xC2FeQ+mHJQQGZN/I8Ci8tzD7alLDAw3DHuF+XrNm38VWtcpAjBayt79AeljIn2ijb8sFiiQVKdW0TMpU587RwgcpaxSkCkYQCWYR0w2803QfEpE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332489; c=relaxed/simple; bh=92IUZTxi6hvpgFf2FVbeHz+VfR9r0NJ5HqxrQy3x3wY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mPRhj/X0xh0mJt1cAVAlBFGnv+TgNIGrLnaeXlsISNJwpu2ggDxXCbxU0Sov0GS5OFH6YcApkjphfAhXLxNcA3D2PHykITFy7dnaRWAWVFCZyJ9cG3OY1cdOsuzmZEiShsIWqYtWbQ851WdoX4ulf1qmUL0BgK/ewWfjnjoWXMk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 968D11692; Wed, 8 Jan 2025 02:35:15 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 67B1F3F673; Wed, 8 Jan 2025 02:34:44 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 12/15] arm64: kpkeys: Support KPKEYS_LVL_PGTABLES Date: Wed, 8 Jan 2025 10:32:47 +0000 Message-ID: <20250108103250.3188419-13-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Enable RW access to KPKEYS_PKEY_PGTABLES (used to map page table pages) if switching to KPKEYS_LVL_PGTABLES, otherwise only grant RO access. Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/kpkeys.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/include/asm/kpkeys.h b/arch/arm64/include/asm/kpkeys.h index e17f6df41873..4854e1f3babd 100644 --- a/arch/arm64/include/asm/kpkeys.h +++ b/arch/arm64/include/asm/kpkeys.h @@ -18,6 +18,8 @@ static inline bool arch_kpkeys_enabled(void) static inline u64 por_set_kpkeys_level(u64 por, int level) { por = por_set_pkey_perms(por, KPKEYS_PKEY_DEFAULT, POE_RXW); + por = por_set_pkey_perms(por, KPKEYS_PKEY_PGTABLES, + level == KPKEYS_LVL_PGTABLES ? POE_RW : POE_R); return por; } From patchwork Wed Jan 8 10:32:48 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930519 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id ED2151FC0ED; Wed, 8 Jan 2025 10:34:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332492; cv=none; b=kawLN8C7sqWPjfJhdMm/HD3RkCkqmElwyKiAKg9AhMbBL3HLiasbuTR8gLAE6METP+1hM2LhAvp5GaiZF8klwiOwasKrsXaCM/MM54iUtv9+XAXSyzjlwuKuVzO3yfzwsiCEdCVf4OgiAEgZfghtfZgwwuwR73+7VmLmewncsIQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332492; c=relaxed/simple; bh=MQcvZUDoJETBDyMXAkvyASuWzoeta5FWJhIth+fShck=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TeOWrNqaMA7XD5jrpHbRlb8fQuBBQ1d6jRUCaQbYPHP3Z+RTDtqSWbTGr6ozv76f7fmccfH4TGiSJJCCJEfJkDk8ai9rAfJ8A8FRfGhgDffFMRE9ZxkrqJbxxLkiKrn0EOE5Z9wwgLotMDPyesDbqlAf2G2e2xyddESILA5LrpI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9C323176C; Wed, 8 Jan 2025 02:35:18 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 829FA3F673; Wed, 8 Jan 2025 02:34:47 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 13/15] arm64: mm: Guard page table writes with kpkeys Date: Wed, 8 Jan 2025 10:32:48 +0000 Message-ID: <20250108103250.3188419-14-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 When CONFIG_KPKEYS_HARDENED_PGTABLES is enabled, page tables (both user and kernel) are mapped with a privileged pkey in the linear mapping. As a result, they can only be written under the kpkeys_hardened_pgtables guard, which sets POR_EL1 appropriately to allow such writes. Use this guard wherever page tables genuinely need to be written, keeping its scope as small as possible (so that POR_EL1 is reset as fast as possible). Where atomics are involved, the guard's scope encompasses the whole loop to avoid switching POR_EL1 unnecessarily. This patch is a no-op if CONFIG_KPKEYS_HARDENED_PGTABLES is disabled (default). Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/pgtable.h | 19 +++++++++++++++++-- arch/arm64/mm/fault.c | 2 ++ 2 files changed, 19 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index f8dac6673887..0d60a49dc234 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -39,6 +39,7 @@ #include #include #include +#include #ifdef CONFIG_TRANSPARENT_HUGEPAGE #define __HAVE_ARCH_FLUSH_PMD_TLB_RANGE @@ -314,6 +315,7 @@ static inline pte_t pte_clear_uffd_wp(pte_t pte) static inline void __set_pte_nosync(pte_t *ptep, pte_t pte) { + guard(kpkeys_hardened_pgtables)(); WRITE_ONCE(*ptep, pte); } @@ -758,6 +760,7 @@ static inline void set_pmd(pmd_t *pmdp, pmd_t pmd) } #endif /* __PAGETABLE_PMD_FOLDED */ + guard(kpkeys_hardened_pgtables)(); WRITE_ONCE(*pmdp, pmd); if (pmd_valid(pmd)) { @@ -825,6 +828,7 @@ static inline void set_pud(pud_t *pudp, pud_t pud) return; } + guard(kpkeys_hardened_pgtables)(); WRITE_ONCE(*pudp, pud); if (pud_valid(pud)) { @@ -906,6 +910,7 @@ static inline void set_p4d(p4d_t *p4dp, p4d_t p4d) return; } + guard(kpkeys_hardened_pgtables)(); WRITE_ONCE(*p4dp, p4d); dsb(ishst); isb(); @@ -1033,6 +1038,7 @@ static inline void set_pgd(pgd_t *pgdp, pgd_t pgd) return; } + guard(kpkeys_hardened_pgtables)(); WRITE_ONCE(*pgdp, pgd); dsb(ishst); isb(); @@ -1233,6 +1239,7 @@ static inline int __ptep_test_and_clear_young(struct vm_area_struct *vma, { pte_t old_pte, pte; + guard(kpkeys_hardened_pgtables)(); pte = __ptep_get(ptep); do { old_pte = pte; @@ -1279,7 +1286,10 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, static inline pte_t __ptep_get_and_clear(struct mm_struct *mm, unsigned long address, pte_t *ptep) { - pte_t pte = __pte(xchg_relaxed(&pte_val(*ptep), 0)); + pte_t pte; + + scoped_guard(kpkeys_hardened_pgtables) + pte = __pte(xchg_relaxed(&pte_val(*ptep), 0)); page_table_check_pte_clear(mm, pte); @@ -1322,7 +1332,10 @@ static inline pte_t __get_and_clear_full_ptes(struct mm_struct *mm, static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long address, pmd_t *pmdp) { - pmd_t pmd = __pmd(xchg_relaxed(&pmd_val(*pmdp), 0)); + pmd_t pmd; + + scoped_guard(kpkeys_hardened_pgtables) + pmd = __pmd(xchg_relaxed(&pmd_val(*pmdp), 0)); page_table_check_pmd_clear(mm, pmd); @@ -1336,6 +1349,7 @@ static inline void ___ptep_set_wrprotect(struct mm_struct *mm, { pte_t old_pte; + guard(kpkeys_hardened_pgtables)(); do { old_pte = pte; pte = pte_wrprotect(pte); @@ -1416,6 +1430,7 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp, pmd_t pmd) { page_table_check_pmd_set(vma->vm_mm, pmdp, pmd); + guard(kpkeys_hardened_pgtables)(); return __pmd(xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd))); } #endif diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index ef63651099a9..ab45047155b9 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -220,6 +220,8 @@ int __ptep_set_access_flags(struct vm_area_struct *vma, if (pte_same(pte, entry)) return 0; + guard(kpkeys_hardened_pgtables)(); + /* only preserve the access flags and write permission */ pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY; From patchwork Wed Jan 8 10:32:49 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930520 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0BC571FC118; Wed, 8 Jan 2025 10:34:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332495; cv=none; b=Skv325h1c+RG6Gs4+B6gmMLK9H5xFTlEAzaXWcuOdOwOI7Pc9+RMlSz/XkxSlGoVmH6LNRpdoBczVjAcjd1Z8UAVMoPknLotCtqQEGKoSGzBAKrE5KS+vfznB1oDczZcTwq83FYxTqddAMKWZTNpeo6pA6nAIlOiOtZAkCD+ktA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332495; c=relaxed/simple; bh=o4svn+5Fa1eoioikppJPbyVvZH1mHcJe8QRlXXRxZEM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Qq5cUIkUY9wnjwDmFxyuv0QTMiMHRrcLZOouDvvTAT3KuB3KLUiA7NLrrGFo/Lk0z15LUrR6yZZMZ+I1zkC0RX1zz4FZ7pzNwhULjESgI6Nb8zhwr7pqmH6l9n87qLAvs/IgxyHZp9lf3FGmV5emNd9zJ1DOBp0+V5rV7CyNots= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B77C613D5; Wed, 8 Jan 2025 02:35:21 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D9D73F673; Wed, 8 Jan 2025 02:34:50 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 14/15] arm64: Enable kpkeys_hardened_pgtables support Date: Wed, 8 Jan 2025 10:32:49 +0000 Message-ID: <20250108103250.3188419-15-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 kpkeys_hardened_pgtables should be enabled as early as possible (if selected). It does however require kpkeys being available, which means on arm64 POE being detected and enabled. POE is a boot feature, so calling kpkeys_hardened_pgtables_enable() just after setup_boot_cpu_features() in smp_prepare_boot_cpu() is the best we can do. With that done, all the bits are in place and we can advertise support for kpkeys_hardened_pgtables by selecting ARCH_HAS_KPKEYS_HARDENED_PGTABLES if ARM64_POE is enabled. Signed-off-by: Kevin Brodsky --- arch/arm64/Kconfig | 1 + arch/arm64/kernel/smp.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 688ffd9bf503..654e6dff9a79 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -2185,6 +2185,7 @@ config ARM64_POE select ARCH_USES_HIGH_VMA_FLAGS select ARCH_HAS_PKEYS select ARCH_HAS_KPKEYS + select ARCH_HAS_KPKEYS_HARDENED_PGTABLES help The Permission Overlay Extension is used to implement Memory Protection Keys. Memory Protection Keys provides a mechanism for diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 3b3f6b56e733..074cab55f9db 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -35,6 +35,7 @@ #include #include #include +#include #include #include @@ -468,6 +469,7 @@ void __init smp_prepare_boot_cpu(void) if (system_uses_irq_prio_masking()) init_gic_priority_masking(); + kpkeys_hardened_pgtables_enable(); kasan_init_hw_tags(); /* Init percpu seeds for random tags after cpus are set up. */ kasan_init_sw_tags(); From patchwork Wed Jan 8 10:32:50 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13930521 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id EEF681FC7E0; Wed, 8 Jan 2025 10:34:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332498; cv=none; b=tgISEtur1RP0eD5JXyhJGvfJUBdlax5N2Q72KgJjn6ZJvoRw/pcaxaazjSBpq33GHcq+hJBFrIDE99C6rgk9Xh0H7tpvFIWv9jEPjdG9ezEPyuKs4xiiZvLR/qdCQIeRCHocnKcl8ijM1BteJ7VuTS3Y7ZkbpdHLKmRwvbSll24= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736332498; c=relaxed/simple; bh=nWneKqwq7JnV4puHbyPciplnZY7JT7T6UCPjmrTMROU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mDkHBUAPrxhi7tanHwE4Xd5CTthQ+w/MKuHglFBkuMPf8vbOTTmLkSzH4qjHfV8IyARJYJ9e5i7ysBav8vquEB54iltM9bYcMA2PT88hb0JJJbGhqmZ0hLuI2i1fVHtIQDHHU0qKnlC2yoEa5VEvQNRgKBs54oxjpz2sVk5uCew= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D32671692; Wed, 8 Jan 2025 02:35:24 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B94133F673; Wed, 8 Jan 2025 02:34:53 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH v2 15/15] mm: Add basic tests for kpkeys_hardened_pgtables Date: Wed, 8 Jan 2025 10:32:50 +0000 Message-ID: <20250108103250.3188419-16-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250108103250.3188419-1-kevin.brodsky@arm.com> References: <20250108103250.3188419-1-kevin.brodsky@arm.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Add basic tests for the kpkeys_hardened_pgtables feature: try to perform a direct write to some kernel and user page table entry and ensure it fails. Signed-off-by: Kevin Brodsky --- mm/Makefile | 1 + mm/kpkeys_hardened_pgtables_test.c | 72 ++++++++++++++++++++++++++++++ security/Kconfig.hardening | 12 +++++ 3 files changed, 85 insertions(+) create mode 100644 mm/kpkeys_hardened_pgtables_test.c diff --git a/mm/Makefile b/mm/Makefile index 130691364172..f7263b7f45b8 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -148,3 +148,4 @@ obj-$(CONFIG_EXECMEM) += execmem.o obj-$(CONFIG_TMPFS_QUOTA) += shmem_quota.o obj-$(CONFIG_PT_RECLAIM) += pt_reclaim.o obj-$(CONFIG_KPKEYS_HARDENED_PGTABLES) += kpkeys_hardened_pgtables.o +obj-$(CONFIG_KPKEYS_HARDENED_PGTABLES_TEST) += kpkeys_hardened_pgtables_test.o diff --git a/mm/kpkeys_hardened_pgtables_test.c b/mm/kpkeys_hardened_pgtables_test.c new file mode 100644 index 000000000000..86d862d43bea --- /dev/null +++ b/mm/kpkeys_hardened_pgtables_test.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +static void write_kernel_pte(struct kunit *test) +{ + pte_t *ptep; + pte_t pte; + int ret; + + /* + * The choice of address is mostly arbitrary - we just need a page + * that is definitely mapped, such as the current function. + */ + ptep = virt_to_kpte((unsigned long)&write_kernel_pte); + KUNIT_ASSERT_NOT_NULL_MSG(test, ptep, "Failed to get PTE"); + + pte = ptep_get(ptep); + pte = set_pte_bit(pte, __pgprot(PTE_WRITE)); + ret = copy_to_kernel_nofault(ptep, &pte, sizeof(pte)); + KUNIT_EXPECT_EQ_MSG(test, ret, -EFAULT, + "Direct PTE write wasn't prevented"); +} + +static void write_user_pmd(struct kunit *test) +{ + pmd_t *pmdp; + pmd_t pmd; + unsigned long uaddr; + int ret; + + uaddr = kunit_vm_mmap(test, NULL, 0, PAGE_SIZE, PROT_READ, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_POPULATE, 0); + KUNIT_ASSERT_NE_MSG(test, uaddr, 0, "Could not create userspace mm"); + + /* We passed MAP_POPULATE so a PMD should already be allocated */ + pmdp = pmd_off(current->mm, uaddr); + KUNIT_ASSERT_NOT_NULL_MSG(test, pmdp, "Failed to get PMD"); + + pmd = pmdp_get(pmdp); + pmd = set_pmd_bit(pmd, __pgprot(PROT_SECT_NORMAL)); + ret = copy_to_kernel_nofault(pmdp, &pmd, sizeof(pmd)); + KUNIT_EXPECT_EQ_MSG(test, ret, -EFAULT, + "Direct PMD write wasn't prevented"); +} + +static int kpkeys_hardened_pgtables_suite_init(struct kunit_suite *suite) +{ + if (!arch_kpkeys_enabled()) { + pr_err("Cannot run kpkeys_hardened_pgtables tests: kpkeys are not supported\n"); + return 1; + } + + return 0; +} + +static struct kunit_case kpkeys_hardened_pgtables_test_cases[] = { + KUNIT_CASE(write_kernel_pte), + KUNIT_CASE(write_user_pmd), + {} +}; + +static struct kunit_suite kpkeys_hardened_pgtables_test_suite = { + .name = "Hardened pgtables using kpkeys", + .test_cases = kpkeys_hardened_pgtables_test_cases, + .suite_init = kpkeys_hardened_pgtables_suite_init, +}; +kunit_test_suite(kpkeys_hardened_pgtables_test_suite); + +MODULE_DESCRIPTION("Tests for the kpkeys_hardened_pgtables feature"); +MODULE_LICENSE("GPL"); diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index 95f93f1d4055..8bc5d7235f6d 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -312,6 +312,18 @@ config KPKEYS_HARDENED_PGTABLES This option has no effect if the system does not support kernel pkeys. +config KPKEYS_HARDENED_PGTABLES_TEST + tristate "KUnit tests for kpkeys_hardened_pgtables" if !KUNIT_ALL_TESTS + depends on KPKEYS_HARDENED_PGTABLES + depends on KUNIT + default KUNIT_ALL_TESTS + help + Enable this option to check that the kpkeys_hardened_pgtables feature + functions as intended, i.e. prevents arbitrary writes to user and + kernel page tables. + + If unsure, say N. + endmenu config CC_HAS_RANDSTRUCT