From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E65FC32750 for ; Tue, 13 Aug 2019 21:03:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5B3952070D for ; Tue, 13 Aug 2019 21:03:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B3952070D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 05A306B0271; Tue, 13 Aug 2019 17:03:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EB20D6B0272; Tue, 13 Aug 2019 17:03:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D7D296B0273; Tue, 13 Aug 2019 17:03:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0125.hostedemail.com [216.40.44.125]) by kanga.kvack.org (Postfix) with ESMTP id 9E2486B0272 for ; Tue, 13 Aug 2019 17:03:00 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 3EC084826 for ; Tue, 13 Aug 2019 21:03:00 +0000 (UTC) X-FDA: 75818629320.03.scale48_1a23196d8e43e X-HE-Tag: scale48_1a23196d8e43e X-Filterd-Recvd-Size: 4593 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Tue, 13 Aug 2019 21:02:59 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Aug 2019 14:02:52 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,382,1559545200"; d="scan'208";a="187901422" Received: from yyu32-desk1.sc.intel.com ([10.144.153.205]) by orsmga002.jf.intel.com with ESMTP; 13 Aug 2019 14:02:50 -0700 From: Yu-cheng Yu 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" , Vedvyas Shanbhogue , Dave Martin Cc: Yu-cheng Yu Subject: [PATCH v8 14/27] x86/mm: Shadow stack page fault error checking Date: Tue, 13 Aug 2019 13:52:12 -0700 Message-Id: <20190813205225.12032-15-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190813205225.12032-1-yu-cheng.yu@intel.com> References: <20190813205225.12032-1-yu-cheng.yu@intel.com> 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: If a page fault is triggered by a shadow stack access (e.g. call/ret) or shadow stack management instructions (e.g. wrussq), then bit[6] of the page fault error code is set. In access_error(), verify a shadow stack page fault is within a shadow stack memory area. It is always an error otherwise. For a valid shadow stack access, set FAULT_FLAG_WRITE to effect copy-on-write. Signed-off-by: Yu-cheng Yu --- arch/x86/include/asm/traps.h | 2 ++ arch/x86/mm/fault.c | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 8691261faeb0..918b0e48b2eb 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -166,6 +166,7 @@ enum { * bit 3 == 1: use of reserved bit detected * bit 4 == 1: fault was an instruction fetch * bit 5 == 1: protection keys block access + * bit 6 == 1: shadow stack access fault */ enum x86_pf_error_code { X86_PF_PROT = 1 << 0, @@ -174,5 +175,6 @@ enum x86_pf_error_code { X86_PF_RSVD = 1 << 3, X86_PF_INSTR = 1 << 4, X86_PF_PK = 1 << 5, + X86_PF_SHSTK = 1 << 6, }; #endif /* _ASM_X86_TRAPS_H */ diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9ceacd1156db..75ec38d125fc 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1187,6 +1187,17 @@ access_error(unsigned long error_code, struct vm_area_struct *vma) (error_code & X86_PF_INSTR), foreign)) return 1; + /* + * Verify X86_PF_SHSTK is within a shadow stack VMA. + * It is always an error if there is a shadow stack + * fault outside a shadow stack VMA. + */ + if (error_code & X86_PF_SHSTK) { + if (!(vma->vm_flags & VM_SHSTK)) + return 1; + return 0; + } + if (error_code & X86_PF_WRITE) { /* write, present and write, not present: */ if (unlikely(!(vma->vm_flags & VM_WRITE))) @@ -1344,6 +1355,13 @@ void do_user_addr_fault(struct pt_regs *regs, perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + /* + * If the fault is caused by a shadow stack access, + * i.e. CALL/RET/SAVEPREVSSP/RSTORSSP, then set + * FAULT_FLAG_WRITE to effect copy-on-write. + */ + if (hw_error_code & X86_PF_SHSTK) + flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_WRITE) flags |= FAULT_FLAG_WRITE; if (hw_error_code & X86_PF_INSTR) -- 2.17.1