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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id d1-20020a170903230100b00177efb56475sm9328173plh.85.2022.10.04.12.24.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Oct 2022 12:24:28 -0700 (PDT) Date: Tue, 4 Oct 2022 12:24:27 -0700 From: Kees Cook To: Mike Rapoport Cc: Rick Edgecombe , 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, jamorris@linux.microsoft.com, dethoma@microsoft.com, Yu-cheng Yu Subject: Re: [OPTIONAL/RFC v2 37/39] x86/cet: Add PTRACE interface for CET Message-ID: <202210041224.E4C63B1@keescook> References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-38-rick.p.edgecombe@intel.com> <202210031658.EEC88324FD@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664911470; 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=TPHGjn63G4Sj8mZqFRVnqMa0MXMfRBRw4erndCFr2yc=; b=Z4ke5Pt2G3gk/tpYFZBwl4PoXrYGCxT0W8TJ/0/vaaEX9s2SXJkbSgEQLV4mduLYirEYW2 IhUDt/FDMXYjxGHwpa9NZgPSkIIjYZpN2ha1F5hrA7Ap/HpppuT571ofvCoGtu3zvd8PIr JJPBCPvIXRmT6nLA5nyO8e+0btu87Rc= ARC-Authentication-Results: i=1; imf20.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=N62in1FH; spf=pass (imf20.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.174 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=1664911470; a=rsa-sha256; cv=none; b=dl1kcyshht/85e5pqnhrziUKctczk0WDa++vrc1r8td0YHIOyAYK3kdTOnsANjadPRnc8e IoM2Me/V8gvLuJb8N1iQH1V/tbhDOwbXI9AbqdoVkQUzqRMTy1RRLBhswmSqY4Yb9Cctvw eTCDVQSbQlzWilEEznbNZx0aZpuUPgo= Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=N62in1FH; spf=pass (imf20.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.174 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: B88431C002F X-Rspam-User: X-Stat-Signature: zpa643cqzwjmdmuxpz1qxfx3uiwcj4hj X-HE-Tag: 1664911470-840194 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 Tue, Oct 04, 2022 at 11:44:16AM +0300, Mike Rapoport wrote: > On Mon, Oct 03, 2022 at 04:59:43PM -0700, Kees Cook wrote: > > On Thu, Sep 29, 2022 at 03:29:34PM -0700, Rick Edgecombe wrote: > > > From: Yu-cheng Yu > > > > > > Some applications (like GDB and CRIU) would like to tweak CET state via > > > > Eee. Does GDB really need this? Can we make this whole thing > > CONFIG-depend on CRIU? > > GDB, at least its Intel fork uses this. I don't see how they can jump > between frames without an ability to modify shadow stack contents. > > Last I looked they used NT_X86_CET to update SSP and ptrace(POKEDATA) to > write to the shadow stack. Okay, thanks! I appreciate having specific examples. :) -- Kees Cook