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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id q12-20020a65624c000000b0043a1c0a0ab1sm6913582pgv.83.2022.10.03.11.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 11:17:11 -0700 (PDT) Date: Mon, 3 Oct 2022 11:17:10 -0700 From: Kees Cook To: Rick Edgecombe Cc: 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 , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, Yu-cheng Yu Subject: Re: [PATCH v2 14/39] mm: Introduce VM_SHADOW_STACK for shadow stack memory Message-ID: <202210031113.FCBAD74@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-15-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220929222936.14584-15-rick.p.edgecombe@intel.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664821033; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=DBHYwkpApAIABn5XcTL1sIyH02ALe7H/mB3LgfPMN3k=; b=SrTbrTDvbDx2+E0dETSR+2QlY2U7tAYrzLmHn1ILcYGFl5qrxrRtouQfh1ITlaLL1F0rKk BgXvtWDKrxLczRlnWCoruczI0ys44g3M3KgfqWmFMjSuSsaGuA5stYh1WOh4Qjszq47rMH AYzslqxh69nuI2f6Wvlqz0+ZANcg9RU= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=kHzL1DsI; spf=pass (imf07.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.49 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664821033; a=rsa-sha256; cv=none; b=Ij/ayTdFGR7Mk5105v+tLKB3s95RNxgZHDq1cfHJozq92TbIPsgXLH98WKaS78qq0B7B7T qFtTgGJW4lNeyCrhb1NoaUXiSgvUp+1u8jWC/Z2euD1k/tG2KqzBs9NcXSlsJXA6N142EF ssfft9APZodfUon+ZEf6sdugu9qmKpY= X-Stat-Signature: y87gpgbx1a8d9cwei4xe56s7nycm77w1 X-Rspamd-Queue-Id: 1F9AF4001E Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=kHzL1DsI; spf=pass (imf07.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.49 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1664821032-841122 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: On Thu, Sep 29, 2022 at 03:29:11PM -0700, Rick Edgecombe wrote: > From: Yu-cheng Yu > > A shadow stack PTE must be read-only and have _PAGE_DIRTY set. However, > read-only and Dirty PTEs also exist for copy-on-write (COW) pages. These > two cases are handled differently for page faults. Introduce > VM_SHADOW_STACK to track shadow stack VMAs. > > Signed-off-by: Yu-cheng Yu > Reviewed-by: Kirill A. Shutemov > Signed-off-by: Rick Edgecombe > Cc: Kees Cook > --- > Documentation/filesystems/proc.rst | 1 + > arch/x86/mm/mmap.c | 2 ++ > fs/proc/task_mmu.c | 3 +++ > include/linux/mm.h | 8 ++++++++ > 4 files changed, 14 insertions(+) > > diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst > index e7aafc82be99..d54ff397947a 100644 > --- a/Documentation/filesystems/proc.rst > +++ b/Documentation/filesystems/proc.rst > @@ -560,6 +560,7 @@ encoded manner. The codes are the following: > mt arm64 MTE allocation tags are enabled > um userfaultfd missing tracking > uw userfaultfd wr-protect tracking > + ss shadow stack page > == ======================================= > > Note that there is no guarantee that every flag and associated mnemonic will > diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c > index c90c20904a60..f3f52c5e2fd6 100644 > --- a/arch/x86/mm/mmap.c > +++ b/arch/x86/mm/mmap.c > @@ -165,6 +165,8 @@ unsigned long get_mmap_base(int is_legacy) > > const char *arch_vma_name(struct vm_area_struct *vma) > { > + if (vma->vm_flags & VM_SHADOW_STACK) > + return "[shadow stack]"; > return NULL; > } I agree with Kirill: this should be in the arch-agnostic code. -- Kees Cook