From patchwork Sun Jan 30 21:18:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Edgecombe, Rick P" X-Patchwork-Id: 12730152 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75A3DC433EF for ; Sun, 30 Jan 2022 21:22:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4B54B6B009E; Sun, 30 Jan 2022 16:22:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4640B6B009F; Sun, 30 Jan 2022 16:22:05 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B6866B00A0; Sun, 30 Jan 2022 16:22:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id 043F26B009E for ; Sun, 30 Jan 2022 16:22:05 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id BDC43181DF763 for ; Sun, 30 Jan 2022 21:22:04 +0000 (UTC) X-FDA: 79088226168.18.4F04365 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by imf27.hostedemail.com (Postfix) with ESMTP id F3BB340002 for ; Sun, 30 Jan 2022 21:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643577724; x=1675113724; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=hiUiL5XEyP01F3eBPpddRbZ/NlSqoVCcrqhafbq6fac=; b=iB0jAcFlq+8JS0YZWEazPiOiMoGj5pmeXAqzLzsQUli8jQ06bIDNqJL3 I1pE1nytAnoJxCPJzeLtrwLgxCFfhTr1VvihUI6cqTzaU33HM4PuiFB5q OCKhrGH09LZztSN7+iDIslXiJiJufAlTOYypJRKDVnj0Mk+GghDAly+X8 IC/TLM89ca3liMkweALLSFkZ8xpogn0C12B3IV35EwTas7PsvoFU8U+8W MGm2EN1MmtJB8X3QSAMjMBNpJDKB0wHOqkA+iI/NMh8UOgVCYNrWh2uhz eX2ECrka36fdVzqUWH2IO+scG3Bn0R3ULuj1SkLRIJLq2IdHBA+U8311C w==; X-IronPort-AV: E=McAfee;i="6200,9189,10243"; a="244970219" X-IronPort-AV: E=Sophos;i="5.88,329,1635231600"; d="scan'208";a="244970219" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2022 13:22:03 -0800 X-IronPort-AV: E=Sophos;i="5.88,329,1635231600"; d="scan'208";a="536856855" Received: from avmallar-mobl1.amr.corp.intel.com (HELO rpedgeco-desk.amr.corp.intel.com) ([10.209.123.171]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2022 13:22:02 -0800 From: Rick Edgecombe To: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Dave Martin , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com Cc: rick.p.edgecombe@intel.com Subject: [PATCH 22/35] x86/mm: Prevent VM_WRITE shadow stacks Date: Sun, 30 Jan 2022 13:18:25 -0800 Message-Id: <20220130211838.8382-23-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220130211838.8382-1-rick.p.edgecombe@intel.com> References: <20220130211838.8382-1-rick.p.edgecombe@intel.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: F3BB340002 X-Rspam-User: nil Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=iB0jAcFl; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf27.hostedemail.com: domain of rick.p.edgecombe@intel.com has no SPF policy when checking 192.55.52.93) smtp.mailfrom=rick.p.edgecombe@intel.com X-Stat-Signature: 8jmnj5dfxtj3xf9k7mtp5wdcqi7i9ics X-HE-Tag: 1643577723-147691 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Shadow stack accesses are writes from handle_mm_fault() perspective. So to generate the correct PTE, maybe_mkwrite() will rely on the presence of VM_SHADOW_STACK or VM_WRITE in the vma. In future patches, when VM_SHADOW_STACK is actually creatable by userspace, a problem could happen if a user calls mprotect( , , PROT_WRITE) on VM_SHADOW_STACK shadow stack memory. The code would then be confused in the event of shadow stack accesses, and create a writable PTE for a shadow stack access. Then the process would fault in a loop. Prevent this from happening by blocking this kind of memory (VM_WRITE and VM_SHADOW_STACK) from being created, instead of complicating the fault handler logic to handle it. Add an x86 arch_validate_flags() implementation to handle the check. Rename the uapi/asm/mman.h header guard to be able to use it for arch/x86/include/asm/mman.h where the arch_validate_flags() will be. Signed-off-by: Rick Edgecombe --- v1: - New patch. arch/x86/include/asm/mman.h | 21 +++++++++++++++++++++ arch/x86/include/uapi/asm/mman.h | 6 +++--- 2 files changed, 24 insertions(+), 3 deletions(-) create mode 100644 arch/x86/include/asm/mman.h diff --git a/arch/x86/include/asm/mman.h b/arch/x86/include/asm/mman.h new file mode 100644 index 000000000000..b44fe31deb3a --- /dev/null +++ b/arch/x86/include/asm/mman.h @@ -0,0 +1,21 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_MMAN_H +#define _ASM_X86_MMAN_H + +#include +#include + +#ifdef CONFIG_X86_SHADOW_STACK +static inline bool arch_validate_flags(unsigned long vm_flags) +{ + if ((vm_flags & VM_SHADOW_STACK) && (vm_flags & VM_WRITE)) + return false; + + return true; +} + +#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags) + +#endif /* CONFIG_X86_SHADOW_STACK */ + +#endif /* _ASM_X86_MMAN_H */ diff --git a/arch/x86/include/uapi/asm/mman.h b/arch/x86/include/uapi/asm/mman.h index d4a8d0424bfb..9704e27c4d24 100644 --- a/arch/x86/include/uapi/asm/mman.h +++ b/arch/x86/include/uapi/asm/mman.h @@ -1,6 +1,6 @@ /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ -#ifndef _ASM_X86_MMAN_H -#define _ASM_X86_MMAN_H +#ifndef _UAPI_ASM_X86_MMAN_H +#define _UAPI_ASM_X86_MMAN_H #define MAP_32BIT 0x40 /* only give out 32bit addresses */ @@ -28,4 +28,4 @@ #include -#endif /* _ASM_X86_MMAN_H */ +#endif /* _UAPI_ASM_X86_MMAN_H */