From patchwork Tue Aug 25 00:25:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu-cheng Yu X-Patchwork-Id: 11734541 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 34793739 for ; Tue, 25 Aug 2020 00:30:11 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0BA2B207D3 for ; Tue, 25 Aug 2020 00:30:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BA2B207D3 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 D08888E001C; Mon, 24 Aug 2020 20:29:41 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id CBD2C8E001B; Mon, 24 Aug 2020 20:29:41 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A43E98E001D; Mon, 24 Aug 2020 20:29:41 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0250.hostedemail.com [216.40.44.250]) by kanga.kvack.org (Postfix) with ESMTP id 79A818E001C for ; Mon, 24 Aug 2020 20:29:41 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 417B9181AEF1D for ; Tue, 25 Aug 2020 00:29:41 +0000 (UTC) X-FDA: 77187207762.18.fork71_44063ee27057 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin18.hostedemail.com (Postfix) with ESMTP id 17818100EC661 for ; Tue, 25 Aug 2020 00:29:41 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,yu-cheng.yu@intel.com,,RULES_HIT:30003:30054:30056:30064,0,RBL:134.134.136.24:@intel.com:.lbl8.mailshell.net-62.18.0.100 64.95.201.95;04yfcdsq17upc5ous54ajzqs1m89zych91ne5baonnfy7rpum4gm9jhhxgua4h3.iqdfeufm19tme9rddinuf5cnn484sowk1pixz4hifo4a4hbow6shxakzbbn4etd.q-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:ft,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: fork71_44063ee27057 X-Filterd-Recvd-Size: 5926 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Tue, 25 Aug 2020 00:29:40 +0000 (UTC) IronPort-SDR: jAy9uyobFu8h3a5XH3/nhoR/75g5swQKkXbPjqu4S1EmkSyXjKaFfnLl7UuusuUS4R6ANxpI0M zA97w6LzJluw== X-IronPort-AV: E=McAfee;i="6000,8403,9723"; a="157061741" X-IronPort-AV: E=Sophos;i="5.76,350,1592895600"; d="scan'208";a="157061741" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2020 17:29:39 -0700 IronPort-SDR: ImGOLQcTSsZKHqrNuXXAiFacd1lAl5GqfBl/eKiS3sJo3nKhmeh7hOcDC+xBM8TDvofjyNNq3y JirNgz2TlPjw== X-IronPort-AV: E=Sophos;i="5.76,350,1592895600"; d="scan'208";a="474135001" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Aug 2020 17:29:39 -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 , Weijiang Yang Cc: Yu-cheng Yu Subject: [PATCH v11 16/25] mm: Add guard pages around a shadow stack. Date: Mon, 24 Aug 2020 17:25:31 -0700 Message-Id: <20200825002540.3351-17-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20200825002540.3351-1-yu-cheng.yu@intel.com> References: <20200825002540.3351-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 17818100EC661 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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: INCSSP(Q/D) increments shadow stack pointer and 'pops and discards' the first and the last elements in the range, effectively touches those memory areas. The maximum moving distance by INCSSPQ is 255 * 8 = 2040 bytes and 255 * 4 = 1020 bytes by INCSSPD. Both ranges are far from PAGE_SIZE. Thus, putting a gap page on both ends of a shadow stack prevents INCSSP, CALL, and RET from going beyond. Signed-off-by: Yu-cheng Yu --- v10: - Define ARCH_SHADOW_STACK_GUARD_GAP. arch/x86/include/asm/processor.h | 10 ++++++++++ include/linux/mm.h | 24 ++++++++++++++++++++---- 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 97143d87994c..01acbd63cad8 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -840,6 +840,16 @@ static inline void spin_lock_prefetch(const void *x) #define STACK_TOP TASK_SIZE_LOW #define STACK_TOP_MAX TASK_SIZE_MAX +/* + * Shadow stack pointer is moved by CALL, JMP, and INCSSP(Q/D). INCSSPQ + * moves shadow stack pointer up to 255 * 8 = ~2 KB (~1KB for INCSSPD) and + * touches the first and the last element in the range, which triggers a + * page fault if the range is not in a shadow stack. Because of this, + * creating 4-KB guard pages around a shadow stack prevents these + * instructions from going beyond. + */ +#define ARCH_SHADOW_STACK_GUARD_GAP PAGE_SIZE + #define INIT_THREAD { \ .addr_limit = KERNEL_DS, \ } diff --git a/include/linux/mm.h b/include/linux/mm.h index 9c2efefb9281..d437ce0c85ac 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2608,6 +2608,10 @@ extern vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf); int __must_check write_one_page(struct page *page); void task_dirty_inc(struct task_struct *tsk); +#ifndef ARCH_SHADOW_STACK_GUARD_GAP +#define ARCH_SHADOW_STACK_GUARD_GAP 0 +#endif + extern unsigned long stack_guard_gap; /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */ extern int expand_stack(struct vm_area_struct *vma, unsigned long address); @@ -2640,9 +2644,15 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m static inline unsigned long vm_start_gap(struct vm_area_struct *vma) { unsigned long vm_start = vma->vm_start; + unsigned long gap = 0; - if (vma->vm_flags & VM_GROWSDOWN) { - vm_start -= stack_guard_gap; + if (vma->vm_flags & VM_GROWSDOWN) + gap = stack_guard_gap; + else if (vma->vm_flags & VM_SHSTK) + gap = ARCH_SHADOW_STACK_GUARD_GAP; + + if (gap != 0) { + vm_start -= gap; if (vm_start > vma->vm_start) vm_start = 0; } @@ -2652,9 +2662,15 @@ static inline unsigned long vm_start_gap(struct vm_area_struct *vma) static inline unsigned long vm_end_gap(struct vm_area_struct *vma) { unsigned long vm_end = vma->vm_end; + unsigned long gap = 0; + + if (vma->vm_flags & VM_GROWSUP) + gap = stack_guard_gap; + else if (vma->vm_flags & VM_SHSTK) + gap = ARCH_SHADOW_STACK_GUARD_GAP; - if (vma->vm_flags & VM_GROWSUP) { - vm_end += stack_guard_gap; + if (gap != 0) { + vm_end += gap; if (vm_end < vma->vm_end) vm_end = -PAGE_SIZE; }