From patchwork Thu May 28 15:49:10 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: 11576243 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 24A101391 for ; Thu, 28 May 2020 15:53:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 167B62071A for ; Thu, 28 May 2020 15:53:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404658AbgE1PxL (ORCPT ); Thu, 28 May 2020 11:53:11 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:33262 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404565AbgE1PxJ (ORCPT ); Thu, 28 May 2020 11:53:09 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jeKqC-0001W7-C9; Thu, 28 May 2020 09:53:08 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1jeKq6-0007zz-5k; Thu, 28 May 2020 09:53:07 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: Linus Torvalds , Oleg Nesterov , Jann Horn , Kees Cook , Greg Ungerer , Rob Landley , Bernd Edlinger , , Al Viro , Alexey Dobriyan , Andrew Morton , Casey Schaufler , linux-security-module@vger.kernel.org, James Morris , "Serge E. Hallyn" , Andy Lutomirski References: <87h7wujhmz.fsf@x220.int.ebiederm.org> <87sgga6ze4.fsf@x220.int.ebiederm.org> <87v9l4zyla.fsf_-_@x220.int.ebiederm.org> <877dx822er.fsf_-_@x220.int.ebiederm.org> <87k10wysqz.fsf_-_@x220.int.ebiederm.org> Date: Thu, 28 May 2020 10:49:10 -0500 In-Reply-To: <87k10wysqz.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Thu, 28 May 2020 10:38:28 -0500") Message-ID: <874ks0xdop.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=1jeKq6-0007zz-5k;;;mid=<874ks0xdop.fsf_-_@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/ELoUISo4voXjVc4cOnoi5+XqInd2HxUI= 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 sa01.xmission.com X-Spam-Level: ** X-Spam-Status: No, score=2.0 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TooManySym_01,XMNoVowels,XMSubLong autolearn=disabled version=3.4.2 X-Spam-Virus: No 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 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 0; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: ; sa01 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **; X-Spam-Relay-Country: X-Spam-Timing: total 515 ms - load_scoreonly_sql: 0.05 (0.0%), signal_user_changed: 3.5 (0.7%), b_tie_ro: 2.3 (0.4%), parse: 1.20 (0.2%), extract_message_metadata: 15 (2.9%), get_uri_detail_list: 1.48 (0.3%), tests_pri_-1000: 17 (3.3%), tests_pri_-950: 1.47 (0.3%), tests_pri_-900: 1.21 (0.2%), tests_pri_-90: 134 (26.0%), check_bayes: 132 (25.7%), b_tokenize: 10 (1.8%), b_tok_get_all: 7 (1.3%), b_comp_prob: 2.2 (0.4%), b_tok_touch_all: 111 (21.5%), b_finish: 0.71 (0.1%), tests_pri_0: 328 (63.6%), check_dkim_signature: 0.40 (0.1%), check_dkim_adsp: 2.5 (0.5%), poll_dns_idle: 0.81 (0.2%), tests_pri_10: 2.6 (0.5%), tests_pri_500: 8 (1.5%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 08/11] exec: In bprm_fill_uid remove unnecessary no new privs check 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 in01.mta.xmission.com) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: When the no new privs code was added[1], a test was added to cap_bprm_set_creds to ensure that the credential change were always reverted if no new privs was set. That test has been refactored into a test to not make the credential change in bprm_fill_uid when no new privs is set. Remove that unncessary test as it can now been seen by a quick inspection that execution can never make it to the test with no new privs set. The same change[1] also added a test that guaranteed the credentials would never change when no_new_privs was set, so the test I am removing was never necessary but historically that was far from obvious. [1]: 259e5e6c75a9 ("Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs") Signed-off-by: "Eric W. Biederman" --- fs/exec.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 8dd7254931dc..af108ecf9632 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1636,16 +1636,12 @@ static void bprm_fill_uid(struct linux_binprm *bprm) if (mode & S_ISUID) { bprm->per_clear = 1; - if (!need_cap || - (ns_capable(new->user_ns, CAP_SETUID) && - !(bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS))) + if (!need_cap || ns_capable(new->user_ns, CAP_SETUID)) new->suid = new->fsuid = new->euid = uid; } if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { bprm->per_clear = 1; - if (!need_cap || - (ns_capable(new->user_ns, CAP_SETGID) && - !(bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS))) + if (!need_cap || ns_capable(new->user_ns, CAP_SETGID)) new->sgid = new->fsgid = new->egid = gid; }