From patchwork Fri Feb 28 20:18:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 11413227 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6F264138D for ; Fri, 28 Feb 2020 20:20:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4FDA2246A8 for ; Fri, 28 Feb 2020 20:20:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726733AbgB1UUX (ORCPT ); Fri, 28 Feb 2020 15:20:23 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:42060 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726400AbgB1UUX (ORCPT ); Fri, 28 Feb 2020 15:20:23 -0500 Received: from in02.mta.xmission.com ([166.70.13.52]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1j7m7S-0001W3-Bn; Fri, 28 Feb 2020 13:20:22 -0700 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1j7m7R-0002lL-EH; Fri, 28 Feb 2020 13:20:22 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: Al Viro , Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module , Akinobu Mita , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Oleg Nesterov , Alexey Gladkov , Linus Torvalds , Jeff Dike , Richard Weinberger , Anton Ivanov References: <20200210150519.538333-8-gladkov.alexey@gmail.com> <87v9odlxbr.fsf@x220.int.ebiederm.org> <20200212144921.sykucj4mekcziicz@comp-core-i7-2640m-0182e6> <87tv3vkg1a.fsf@x220.int.ebiederm.org> <87v9obipk9.fsf@x220.int.ebiederm.org> <20200212200335.GO23230@ZenIV.linux.org.uk> <20200212203833.GQ23230@ZenIV.linux.org.uk> <20200212204124.GR23230@ZenIV.linux.org.uk> <87lfp7h422.fsf@x220.int.ebiederm.org> <87pnejf6fz.fsf@x220.int.ebiederm.org> <871rqpaswu.fsf_-_@x220.int.ebiederm.org> <871rqk2brn.fsf_-_@x220.int.ebiederm.org> <878skmsbyy.fsf_-_@x220.int.ebiederm.org> Date: Fri, 28 Feb 2020 14:18:14 -0600 In-Reply-To: <878skmsbyy.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Fri, 28 Feb 2020 14:17:41 -0600") Message-ID: <8736ausby1.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1j7m7R-0002lL-EH;;;mid=<8736ausby1.fsf_-_@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+WuHbOA66kXQc+ge/fBSMlwuwEjasAimw= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa06.xmission.com X-Spam-Level: ** X-Spam-Status: No, score=2.5 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TM2_M_HEADER_IN_MSG,T_TooManySym_01, T_TooManySym_02,XMNoVowels,XMSubLong,XM_Body_Dirty_Words autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.5 XM_Body_Dirty_Words Contains a dirty word * 0.0 T_TooManySym_02 5+ unique symbols in subject * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **; X-Spam-Relay-Country: X-Spam-Timing: total 489 ms - load_scoreonly_sql: 0.04 (0.0%), signal_user_changed: 2.7 (0.6%), b_tie_ro: 1.89 (0.4%), parse: 1.23 (0.3%), extract_message_metadata: 22 (4.5%), get_uri_detail_list: 1.65 (0.3%), tests_pri_-1000: 37 (7.5%), tests_pri_-950: 1.26 (0.3%), tests_pri_-900: 1.05 (0.2%), tests_pri_-90: 25 (5.2%), check_bayes: 24 (4.9%), b_tokenize: 9 (1.8%), b_tok_get_all: 7 (1.5%), b_comp_prob: 2.2 (0.5%), b_tok_touch_all: 3.8 (0.8%), b_finish: 0.69 (0.1%), tests_pri_0: 386 (79.0%), check_dkim_signature: 0.52 (0.1%), check_dkim_adsp: 2.6 (0.5%), poll_dns_idle: 0.40 (0.1%), tests_pri_10: 2.0 (0.4%), tests_pri_500: 7 (1.5%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 1/3] uml: Don't consult current to find the proc_mnt in mconsole_proc X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Inspection of the control flow reveals that mconsole_proc is either called from mconsole_stop called from mc_work_proc or from mc_work_proc directly. The function mc_work_proc is dispatched to a kernel thread with schedule_work. All of the threads that run dispatched by schedule_work are in the init pid namespace. So make the code clearer and by using init_pid_ns instead of task_active_pid_ns(current). Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Signed-off-by: "Eric W. Biederman" --- arch/um/drivers/mconsole_kern.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c index b80a1d616e4e..e8f5c81c2c6c 100644 --- a/arch/um/drivers/mconsole_kern.c +++ b/arch/um/drivers/mconsole_kern.c @@ -123,7 +123,7 @@ void mconsole_log(struct mc_request *req) void mconsole_proc(struct mc_request *req) { - struct vfsmount *mnt = task_active_pid_ns(current)->proc_mnt; + struct vfsmount *mnt = init_pid_ns.proc_mnt; char *buf; int len; struct file *file;