From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1520279004; cv=none; d=google.com; s=arc-20160816; b=oPvX2aHDcoVR/bfLT1cRlOhVVKr9d6SxOfro9+PlQdnVUxkP6oy4pnP2iMY0d+hGmv wUlUBnSCo+uwwoD3MloeTFc62W9vaFG28+NFvUk0iKI/u1hJnkY5yNN6Is3ZLLqnzYwT x19je9EO9ECC4fqYZxIkBBakpaVnKcPTwRGYGy3XdTSueel6m+MJ4ciefzidls7zySiO fusmVMMOKGtPQPr0PjqZgzHHqRMKg5UhO8fEyAgU2zLqigKX1ZxOmvZGzmg3ckFZUC9y 37ZUIHU75TzwltU1F1yAve7vedHxuJsbgaimzuLTS/om1KXDnufY6aWhyIXxTwDaieNv DCpw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:to:subject :arc-authentication-results; bh=04Ctnp8qnSc/wv8kTmGOaNYMW19rQ1oTNrUMpr/WQMo=; b=cP8nnLRtaZkgolGSXizJG0PbI3zHLmnOUC+zY7czU8bWv/HznxDmutmp32wO/KKZXi 2ESmWvgIEv5NIA1MHgA9a1hOezRyJM6Eo0K0i87YczyIdN0PFfHZ/yYtPNk4/zUrxl7G uouKmBni9P2Y3OX7x5RXzm4RX6qAdBmkTf+H7+L2atrXbkEsCW8fJ7WU0qJ6Xsy1cQfl UFuS0+j+IPiHjvfAKs5yiIkfhOWV0KBeqEZTLxizUx8EoUzVj5J/aJq1wEjqyVpQBb4F MUTrRqhhMg+vhWY93nHL8XXXK5VAJYbTo/2oZwpR78Muqyb+CFP7mq1F+d8oPx9GpcCm 1VBg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of labbott@redhat.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=labbott@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of labbott@redhat.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=labbott@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Google-Smtp-Source: AG47ELtNiDIKupXPmpXnsWg9zljzk+I8pbJwEb0QQV1x/P6oN3xxRWCCCJbit6RAco5ou0Qu7qgxow== Subject: Re: [PATCH RFC v9 2/7] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls To: Dave Hansen , Alexander Popov , kernel-hardening@lists.openwall.com, Kees Cook , PaX Team , Brad Spengler , Ingo Molnar , Andy Lutomirski , Tycho Andersen , Mark Rutland , Ard Biesheuvel , Borislav Petkov , Richard Sandiford , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , "Dmitry V . Levin" , Emese Revfy , Jonathan Corbet , Andrey Ryabinin , "Kirill A . Shutemov" , Thomas Garnier , Andrew Morton , Alexei Starovoitov , Josef Bacik , Masami Hiramatsu , Nicholas Piggin , Al Viro , "David S . Miller" , Ding Tianhong , David Woodhouse , Josh Poimboeuf , Steven Rostedt , Dominik Brodowski , Juergen Gross , Greg Kroah-Hartman , Dan Williams , Mathias Krause , Vikas Shivappa , Kyle Huey , Dmitry Safonov , Will Deacon , Arnd Bergmann , x86@kernel.org, linux-kernel@vger.kernel.org References: <1520107232-14111-1-git-send-email-alex.popov@linux.com> <1520107232-14111-3-git-send-email-alex.popov@linux.com> From: Laura Abbott Message-ID: <94f268b2-31a4-620a-86ed-325d5bb33c57@redhat.com> Date: Mon, 5 Mar 2018 11:43:19 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1593947982901315923?= X-GMAIL-MSGID: =?utf-8?q?1594128077298743305?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 03/05/2018 08:41 AM, Dave Hansen wrote: > On 03/03/2018 12:00 PM, Alexander Popov wrote: >> Documentation/x86/x86_64/mm.txt | 2 + >> arch/Kconfig | 27 ++++++++++ >> arch/x86/Kconfig | 1 + >> arch/x86/entry/entry_32.S | 88 +++++++++++++++++++++++++++++++ >> arch/x86/entry/entry_64.S | 108 +++++++++++++++++++++++++++++++++++++++ >> arch/x86/entry/entry_64_compat.S | 11 ++++ > > This is a *lot* of assembly. I wonder if you tried at all to get more > of this into C or whether you just inherited the assembly from the > original code? > This came up previously http://www.openwall.com/lists/kernel-hardening/2017/10/23/5 there were concerns about trusting C to do the right thing as well as speed. Thanks, Laura