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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id 129-20020a621787000000b0053e20a0333fsm8096309pfx.93.2022.10.03.15.28.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Oct 2022 15:28:48 -0700 (PDT) Date: Mon, 3 Oct 2022 15:28:47 -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 Subject: Re: [PATCH v2 29/39] x86/cet/shstk: Support wrss for userspace Message-ID: <202210031525.78F3FA8@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-30-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220929222936.14584-30-rick.p.edgecombe@intel.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664836129; 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=+wnywtAQvf5k8l6QfV3gcIXHNKvc8BplZWtX49oDhHc=; b=0zRzPViK3u9t1sf7RlUFnIQb/agRoV7sK7Al7qu6Wbo/ZaXyd0W0N4bg+qssXaC65TQJCK PyvSxTDvp662IatlxMBiLpZzOnLaeaRvVqLJ/djep928N8TmI6A3i2C0BcZIPv6Abgij6P d3Evc7MILFsJTSQ5hO650wh3/HG5H18= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b="H/p7lvN0"; spf=pass (imf30.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.177 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=1664836129; a=rsa-sha256; cv=none; b=RF9Sf8E9DEOaYyI0UOROCV6E+RyeIHsqtzFPWgfo3aPZr4UYopGIowW310/QJwRj1IEQ0/ rK0WaP/V12djR/7QXfOjg8GN9umYXciHtjwlM4CXnp6k0tLrFek0Ol+wxLq/LDJImmHrWN lgHlen9AALNkIjlfULICazwenb1lBK4= X-Stat-Signature: gq3q7bqtmkpshbmu9u3nuiq6w8himfoz X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C127D80007 Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b="H/p7lvN0"; spf=pass (imf30.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.177 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspam-User: X-HE-Tag: 1664836129-495865 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 03:29:26PM -0700, Rick Edgecombe wrote: > For the current shadow stack implementation, shadow stacks contents easily > be arbitrarily provisioned with data. I can't parse this sentence. > This property helps apps protect > themselves better, but also restricts any potential apps that may want to > do exotic things at the expense of a little security. Is anything using this right now? Wouldn't thing be safer without WRSS? (Why can't we skip this patch?) -- Kees Cook