Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932711AbcLMM5k (ORCPT ); Tue, 13 Dec 2016 07:57:40 -0500 Received: from mail-wj0-f193.google.com ([209.85.210.193]:34288 "EHLO mail-wj0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932312AbcLMM5i (ORCPT ); Tue, 13 Dec 2016 07:57:38 -0500 MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com In-Reply-To: <9f32a79b-5795-bff4-b741-bf927a525149@gmail.com> References: <51643019-bb42-4066-c824-c55b9e668ac6@man7.org> <25262.1481628931@warthog.procyon.org.uk> <9f32a79b-5795-bff4-b741-bf927a525149@gmail.com> From: "Michael Kerrisk (man-pages)" Date: Tue, 13 Dec 2016 13:57:16 +0100 Message-ID: Subject: Re: Revised keyrings(7) man page for review To: David Howells , Michael Kerrisk Cc: Michael Kerrisk , lkml , Eugene Syromyatnikov , keyrings@vger.kernel.org, linux-man Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id uBDCvjUU032237 Content-Length: 1757 Lines: 49 Hello David, Amended a piece here after Eugene's note about encrypted keys. On 13 December 2016 at 13:43, Michael Kerrisk (man-pages) wrote: > Hi David, > > On 12/13/2016 12:35 PM, David Howells wrote: >> Michael Kerrisk wrote: >> >>> "big_key" (since Linux 3.13) >>> This key type is similar to the "user" key type, but it >>> may hold a payload of up to 1MiB in size. The data may >>> be stored in the swap space rather than in kernel memory >> >> stored encrypted (as of 4.8). > > Added "encrypted". So, I've updated this piece a couple of times since the draft that you reviewed, and by now it reads: "big_key" (since Linux 3.13) This key type is similar to the "user" key type, but it may hold a payload of up to 1 MiB in size. This key type is useful for tasks such as holding Kerberos ticket caches. The payload data may be stored in the swap space rather than in kernel memory if the data size exceeds the overhead of storing the data encrypted in swap space. (A tmpfs file is used, which requires filesystem structures to be allo‐ cated in the kernel; The size of these structures deter‐ mines the size threshold above which the tmpfs storage method is used.) Since Linux 4.8, payload data is encrypted, to prevent it being written unencrypted into swap space. Okay? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/