From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71A50C2D0DB for ; Mon, 27 Jan 2020 19:29:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4DFE124681 for ; Mon, 27 Jan 2020 19:29:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726327AbgA0T3L (ORCPT ); Mon, 27 Jan 2020 14:29:11 -0500 Received: from relay.sw.ru ([185.231.240.75]:47718 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgA0T3L (ORCPT ); Mon, 27 Jan 2020 14:29:11 -0500 Received: from vvs-ws.sw.ru ([172.16.24.21]) by relay.sw.ru with esmtp (Exim 4.92.3) (envelope-from ) id 1iwA31-00072K-M9; Mon, 27 Jan 2020 22:27:47 +0300 Subject: Re: [PATCH 1/1] proc_keys_next should increase position index To: David Howells Cc: keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, Jarkko Sakkinen , James Morris , "Serge E. Hallyn" References: <1451508.1580125174@warthog.procyon.org.uk> From: Vasily Averin Message-ID: Date: Mon, 27 Jan 2020 22:27:47 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <1451508.1580125174@warthog.procyon.org.uk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On 1/27/20 2:39 PM, David Howells wrote: > I don't see the effect you're talking about with /proc/keys. I see the > following: > > [root@andromeda ~]# dd if=/proc/keys bs=40 skip=1 > dd: /proc/keys: cannot skip to specified offset > > and then it follows up with the normal content with no obvious duplicates (the > lines are numbered ascendingly in the first column). > > I think I may be being confused by what you mean by "the last line". on unpatched kernel $ uname -a Linux vvsx1 5.3.0-26-generic #28~18.04.1-Ubuntu SMP Wed Dec 18 16:40:14 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux $ dd if=/proc/keys bs=1 # VvS: full usual output 0f6bfdf5 I--Q--- 2 perm 3f010000 1000 1000 user 4af2f79ab8848d0a: 740 1fb91b32 I--Q--- 3 perm 1f3f0000 1000 65534 keyring _uid.1000: 2 27589480 I--Q--- 1 perm 0b0b0000 0 0 user invocation_id: 16 2f33ab67 I--Q--- 152 perm 3f030000 0 0 keyring _ses: 2 33f1d8fa I--Q--- 4 perm 3f030000 1000 1000 keyring _ses: 1 3d427fda I--Q--- 2 perm 3f010000 1000 1000 user 69ec44aec7678e5a: 740 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 521+0 records in 521+0 records out 521 bytes copied, 0,00123769 s, 421 kB/s $ dd if=/proc/keys bs=500 skip=1 # read after lseek in middle of last line dd: /proc/keys: cannot skip to specified offset g _uid_ses.1000: 1 <<<< end of last line 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 <<<< and whole last lien again 0+1 records in 0+1 records out 97 bytes copied, 0,000135035 s, 718 kB/s $ dd if=/proc/keys bs=1000 skip=1 # read after lseek beyond end of file dd: /proc/keys: cannot skip to specified offset 3ead4096 I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 <<<< generates last line 0+1 records in 0+1 records out 76 bytes copied, 0,000119981 s, 633 kB/s On patched kernel: [test@localhost ~]$ uname -a Linux localhost.localdomain 5.5.0-rc6-00151-gd8d014f #8 SMP Fri Jan 24 13:25:06 MSK 2020 x86_64 x86_64 x86_64 GNU/Linux [test@localhost ~]$ dd if=/proc/keys bs=1 06e8bec5 I--Q--- 4 perm 1f3f0000 1000 65534 keyring _uid.1000: empty 1b7ee8ed I--Q--- 11 perm 3f030000 1000 1000 keyring _ses: 1 2c1a365d I--Q--- 1 perm 1f3f0000 1000 65534 keyring _uid_ses.1000: 1 3f5823b4 I--Q--- 6 perm 3f030000 1000 1000 keyring _ses: 1 286+0 records in 286+0 records out 286 bytes copied, 0,000414581 s, 690 kB/s [test@localhost ~]$ dd if=/proc/keys bs=270 skip=1 # VvS: read after lseek in middle of last line dd: /proc/keys: cannot skip to specified offset yring _ses: 1 <<<< only end of last line was generated, as expected 0+1 records in 0+1 records out 16 bytes copied, 7,7199e-05 s, 207 kB/s [test@localhost ~]$ dd if=/proc/keys bs=1000 skip=1 # VvS: read after lseek beond end of file dd: /proc/keys: cannot skip to specified offset 0+0 records in <<<< nothing was generated, as expected 0+0 records out 0 bytes copied, 8,8036e-05 s, 0,0 kB/s