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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9D28C05027 for ; Sun, 19 Feb 2023 20:45:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 5F067280002; Sun, 19 Feb 2023 15:45:04 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5793E280001; Sun, 19 Feb 2023 15:45:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 419F2280002; Sun, 19 Feb 2023 15:45:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 3122F280001 for ; Sun, 19 Feb 2023 15:45:04 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 02B931A0145 for ; Sun, 19 Feb 2023 20:45:03 +0000 (UTC) X-FDA: 80485220928.29.35BFC40 Received: from mail-pf1-f182.google.com (mail-pf1-f182.google.com [209.85.210.182]) by imf06.hostedemail.com (Postfix) with ESMTP id 248BA18000D for ; Sun, 19 Feb 2023 20:45:01 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=a0WqQeTk; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf06.hostedemail.com: domain of keescook@chromium.org designates 209.85.210.182 as permitted sender) smtp.mailfrom=keescook@chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1676839502; 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=ivbvfQbVG34mV5fGNdTXCKeRtWO6+zGGPz2rG7C0C6w=; b=KvTxTEJQWPzBulVlPlF/weHXjqiFuuBg7fwIDUoM5DoyL2mS2aWuGDeLm70BvQmXtyTAYM p9PEyTxkPoluR8PrHnrd2a/55b5QTGVpRkeG0sxgTj++jw1age0PEwRFntala1OOX6G0JO 0s+j+UD7juWsjj/vhMoKG4Ovh3wZXjM= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=a0WqQeTk; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf06.hostedemail.com: domain of keescook@chromium.org designates 209.85.210.182 as permitted sender) smtp.mailfrom=keescook@chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1676839502; a=rsa-sha256; cv=none; b=KygoKjX02EiHtW50GcuM82aHaBZXou1MBOKMBkZiQ+u4Gk+cYdtej8via8kdDEg3STPaLM 7K550StyWV3Rcj5S75pIDUZ5GedWd/CcD7aUoHYYTshSJjydoUjyiGVdGAidJP5oIf6/dx w0e62FMImztfdtZJx4lrNzwN0jhPiKI= Received: by mail-pf1-f182.google.com with SMTP id n6so680705pfu.10 for ; Sun, 19 Feb 2023 12:45:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=in-reply-to:content-disposition:mime-version:references:subject:cc :to:from:date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=ivbvfQbVG34mV5fGNdTXCKeRtWO6+zGGPz2rG7C0C6w=; b=a0WqQeTkbEtGlN+AAh0UBcplRe3Mq1/PhtZRmrjopxv2t4we9NJa16H9gVO5Nt9zq6 M+hSLcbgLF7KlsCjphoqcVh36Tytu3ViR0yC0vU2D0roilgekeIRwZ59kfbQjm4Cycxv NoW3HvSF0n4nuAnCmwMOZZCBMBfln0uOi6eYo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:subject:cc :to:from:date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ivbvfQbVG34mV5fGNdTXCKeRtWO6+zGGPz2rG7C0C6w=; b=lje1ZkPOlBwy0y67jCqXtxZ3XSbUToR7iLwI7hVXFraLh1MVbbCmN/5p4dMs9rREhO GQoNIqtSGeKQ5cbphlxMj0UW3SyUULknO0qPdp4FqlgYntWRK8g75uZQDTjN5OGbgEel bf5p1DSkgOHW28/4g8NpB3QSMcV84mQJls0skb7yXJBRE7BijKb58xVZokKezjClVb9K 7cWYZxdkJrkqtkbjVDaIkBa0cT013Trf8febjEt+ANBLc1BWVmoC8gN9MlCbNOlSSA81 jzsuAQpuePd3eqKWyeRNTWDjfvHYmmxtb76cyz2DKNGB1Fmw20lNinAT5kfjHTNPrCEX T9KQ== X-Gm-Message-State: AO0yUKXs5ipA8NQaHw6wclB2TPldMbW8pO9cPcNyfOk43snNLm8DMkHx ZmSOduRbtLd3HaWllVjfQ9RUp2ChqJeO2H2e X-Google-Smtp-Source: AK7set/IGqCk6VROgNeNmOOU78n8oFKLxXKiLNswklcmwgoePRvTjTd1R1Aqt+oSmIUX0KDigV58WQ== X-Received: by 2002:aa7:8429:0:b0:5a8:ae97:2273 with SMTP id q9-20020aa78429000000b005a8ae972273mr1008006pfn.25.1676839500996; Sun, 19 Feb 2023 12:45:00 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id n11-20020a62e50b000000b00586fbbdf6e4sm6246179pff.34.2023.02.19.12.45.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Feb 2023 12:45:00 -0800 (PST) Message-ID: <63f28a4c.620a0220.cf190.b2fa@mx.google.com> X-Google-Original-Message-ID: <202302191244.@keescook> Date: Sun, 19 Feb 2023 12:45:00 -0800 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 , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com, david@redhat.com, debug@rivosinc.com Subject: Re: [PATCH v6 27/41] x86/mm: Warn if create Write=0,Dirty=1 with raw prot References: <20230218211433.26859-1-rick.p.edgecombe@intel.com> <20230218211433.26859-28-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230218211433.26859-28-rick.p.edgecombe@intel.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 248BA18000D X-Stat-Signature: ctpefkmhgoceroawssxb68eecsygrb7u X-HE-Tag: 1676839501-736193 X-HE-Meta: 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 CpAqsu4a MOwEjs7bo5oOqQUG5kPkS3u7e7EUxypzE9CE0XIUOGSOc0g1EWvWn1ZJ+iJWXuTZm6ygWIXYXOM8MwRxl2BH9zggIkNlNc+XeqfdSG6g6rsNt2+DOoc1Q1LEHWciNtAO06NWwOLHi0bR/fpyXB/otwydSrvdV513Kb6HnPXl7WS+FdqnUhEaKz/ZnToGFTQmmMU8BX7R7sOsp+M9i1h0PsiCGBTLH4cS/XYQcEKkOemnnAzcbhN+UOleH2bFLK66Qb7UAlYhZOZ77FL0Jh5jUsRt5TnPYCmKPmaJHtZlRBe4X8wswuIPGMek5jfe9Fi4fMnaLG0S9cf9f0hKmPLwlys5TXt7OidxlQ2YiwdaBnn3Knmov02dmaO7RLUhtHLHDJ8xzudUzPBFd2tEo5uULMaNBh03BlRcUTGoIMMOWxUKjLsw= 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 Sat, Feb 18, 2023 at 01:14:19PM -0800, Rick Edgecombe wrote: > When user shadow stack is use, Write=0,Dirty=1 is treated by the CPU as > shadow stack memory. So for shadow stack memory this bit combination is > valid, but when Dirty=1,Write=1 (conventionally writable) memory is being > write protected, the kernel has been taught to transition the Dirty=1 > bit to SavedDirty=1, to avoid inadvertently creating shadow stack > memory. It does this inside pte_wrprotect() because it knows the PTE is > not intended to be a writable shadow stack entry, it is supposed to be > write protected. > > However, when a PTE is created by a raw prot using mk_pte(), mk_pte() > can't know whether to adjust Dirty=1 to SavedDirty=1. It can't > distinguish between the caller intending to create a shadow stack PTE or > needing the SavedDirty shift. > > The kernel has been updated to not do this, and so Write=0,Dirty=1 > memory should only be created by the pte_mkfoo() helpers. Add a warning > to make sure no new mk_pte() start doing this. > > Tested-by: Pengfei Xu > Signed-off-by: Rick Edgecombe > > --- > v6: > - New patch (Note, this has already been a useful warning, it caught the > newly added set_memory_rox() doing this) > --- > arch/x86/include/asm/pgtable.h | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index f3dc16fc4389..db8fe5511c74 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -1032,7 +1032,15 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd) > * (Currently stuck as a macro because of indirect forward reference > * to linux/mm.h:page_to_nid()) > */ > -#define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot)) > +#define mk_pte(page, pgprot) \ > +({ \ > + pgprot_t __pgprot = pgprot; \ > + \ > + WARN_ON_ONCE(cpu_feature_enabled(X86_FEATURE_USER_SHSTK) && \ > + (pgprot_val(__pgprot) & (_PAGE_DIRTY | _PAGE_RW)) == \ > + _PAGE_DIRTY); \ > + pfn_pte(page_to_pfn(page), __pgprot); \ > +}) This only warns? Should it also enforce the state? -- Kees Cook