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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, jamorris@linux.microsoft.com, dethoma@microsoft.com Subject: Re: [PATCH v2 29/39] x86/cet/shstk: Support wrss for userspace Message-ID: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-30-rick.p.edgecombe@intel.com> <202210031525.78F3FA8@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202210031525.78F3FA8@keescook> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664872284; 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=PsIWLU1/bgsufPkYPxRaL0HhJrGXrcqo4Im6EQtPlns=; b=Z/p9Z4x2fXkGAujWwPkvh9mF3Xdu5q0SPFAXEX6WoGxtEebv/HIMzE7G9JCXY/EAy9UqYm HM1FuvvIx7wGtUH6cs1mMcHObsHTGTVS46tEKFCUaHvqBTauldJz9cLkCgj29JY1qKrXLK Z+XB1JChZ9fFXSa1VNQ+/Hd+MpRBtfQ= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=e6YMHUum; spf=pass (imf04.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664872284; a=rsa-sha256; cv=none; b=j+4nr6TWJn3n7o7bBA9vNru9vhqXPx5C33Od1pRhfua9vVaZYWZCdccPmL/N22oTOfYzdu 6LagUV8E/yiU41bjt7PSd83JdLe4J3vQEjXi+fbl+p0iEjsUcfaRVvD7UTFO5m9MxLEh79 ZoKCVqyFMgeb1dnVTmxAACpFSd1TTNw= X-Rspamd-Queue-Id: EE17F40016 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=e6YMHUum; spf=pass (imf04.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-Rspamd-Server: rspam06 X-Rspam-User: X-Stat-Signature: xcdx7b6dhfj14ogz9pjuxefris8ko869 X-HE-Tag: 1664872283-955732 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 Mon, Oct 03, 2022 at 03:28:47PM -0700, Kees Cook wrote: > 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?) CRIU uses WRSS to restore the shadow stack contents. > -- > Kees Cook -- Sincerely yours, Mike.