From patchwork Fri Dec 6 10:11:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13896864 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A9784202F7E; Fri, 6 Dec 2024 10:13:51 +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=1733480033; cv=none; b=NTuAXpPEUBI0KDQhf6oxNhBWQw7sdyotam7ChmwnujFIMISb4D7ALSqnKf7PMk72J57b69hnyqAdMyGdd5Lj3pBLk5C8TkT6XQ8BWhvnemr5rvMXLfCk0uax/34RSWvfkLGAj2zh+6ytRfyRr/Mnz9pySB6Aey68lY5/PIsD9Qs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733480033; c=relaxed/simple; bh=pOja1sM50YpIU+w+RhbNwS4Z/W8PzSFIuNa4L8jerOU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Cqb4rNkaBlwe17H44FVqT4PaxrUT70OaqomjKLz5ijRNveqneuF/QmrQunFjL4RKEzbU50qerga07S2e77WjMDw61ooM9dCGY3//NPeoKgqo/uAUNoLSKVZKdJyhIWm0PVv1ivcWCBi5n0CYuFCqhHpfA2T6Cd2QUDz1YEQJNFc= 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 58708169E; Fri, 6 Dec 2024 02:14:19 -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 6ED083F7D8; Fri, 6 Dec 2024 02:13:48 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , aruna.ramakrishna@oracle.com, broonie@kernel.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, jannh@google.com, jeffxu@chromium.org, joey.gouly@arm.com, kees@kernel.org, maz@kernel.org, pierre.langlois@arm.com, qperret@google.com, ryan.roberts@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org Subject: [RFC PATCH 12/16] arm64: mm: Map p4d/pgd with privileged pkey Date: Fri, 6 Dec 2024 10:11:06 +0000 Message-ID: <20241206101110.1646108-13-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241206101110.1646108-1-kevin.brodsky@arm.com> References: <20241206101110.1646108-1-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 p4d/pgd pages using a privileged pkey (KPKEYS_PKEY_PGTABLES), so that they can only be written under guard(kpkeys_hardened_pgtables). The case where pgd is not page-sized is not currently handled - this is pending support for pkeys in kmem_cache. This patch is a no-op if CONFIG_KPKEYS_HARDENED_PGTABLES is disabled (default). Signed-off-by: Kevin Brodsky --- arch/arm64/include/asm/pgalloc.h | 21 ++++++++++++++++++--- arch/arm64/mm/pgd.c | 30 ++++++++++++++++++++++++++++-- 2 files changed, 46 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h index e75422864d1b..c006aecd6ba5 100644 --- a/arch/arm64/include/asm/pgalloc.h +++ b/arch/arm64/include/asm/pgalloc.h @@ -88,18 +88,33 @@ static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgdp, p4d_t *p4dp) static inline p4d_t *p4d_alloc_one(struct mm_struct *mm, unsigned long addr) { gfp_t gfp = GFP_PGTABLE_USER; + int ret; if (mm == &init_mm) gfp = GFP_PGTABLE_KERNEL; - return (p4d_t *)get_zeroed_page(gfp); + + addr = get_zeroed_page(gfp); + if (!addr) + return NULL; + + ret = kpkeys_protect_pgtable_memory(addr, 1); + if (ret) { + free_page(addr); + return NULL; + } + + return (p4d_t *)addr; } static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d) { + unsigned long addr = (unsigned long)p4d; + if (!pgtable_l5_enabled()) return; - BUG_ON((unsigned long)p4d & (PAGE_SIZE-1)); - free_page((unsigned long)p4d); + BUG_ON(addr & (PAGE_SIZE-1)); + kpkeys_unprotect_pgtable_memory(addr, 1); + free_page(addr); } #define __p4d_free_tlb(tlb, p4d, addr) p4d_free((tlb)->mm, p4d) diff --git a/arch/arm64/mm/pgd.c b/arch/arm64/mm/pgd.c index 0c501cabc238..3577cc1821af 100644 --- a/arch/arm64/mm/pgd.c +++ b/arch/arm64/mm/pgd.c @@ -28,12 +28,38 @@ static bool pgdir_is_page_size(void) return false; } +static pgd_t *pgd_page_alloc(gfp_t gfp) +{ + unsigned long addr; + int ret; + + addr = __get_free_page(gfp); + if (!addr) + return NULL; + + ret = kpkeys_protect_pgtable_memory(addr, 1); + if (ret) { + free_page(addr); + return NULL; + } + + return (pgd_t *)addr; +} + +static void pgd_page_free(pgd_t *pgd) +{ + unsigned long addr = (unsigned long)pgd; + + kpkeys_unprotect_pgtable_memory(addr, 1); + free_page(addr); +} + pgd_t *pgd_alloc(struct mm_struct *mm) { gfp_t gfp = GFP_PGTABLE_USER; if (pgdir_is_page_size()) - return (pgd_t *)__get_free_page(gfp); + return pgd_page_alloc(gfp); else return kmem_cache_alloc(pgd_cache, gfp); } @@ -41,7 +67,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm) void pgd_free(struct mm_struct *mm, pgd_t *pgd) { if (pgdir_is_page_size()) - free_page((unsigned long)pgd); + pgd_page_free(pgd); else kmem_cache_free(pgd_cache, pgd); }