From patchwork Wed Aug 23 10:12:53 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Guy Briggs X-Patchwork-Id: 9917029 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 601A560327 for ; Wed, 23 Aug 2017 10:13:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 525F3288B6 for ; Wed, 23 Aug 2017 10:13:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 474A92893D; Wed, 23 Aug 2017 10:13:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98B66288B6 for ; Wed, 23 Aug 2017 10:13:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852AbdHWKNm (ORCPT ); Wed, 23 Aug 2017 06:13:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60698 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753844AbdHWKNl (ORCPT ); Wed, 23 Aug 2017 06:13:41 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6ACFCC047B8C; Wed, 23 Aug 2017 10:13:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 6ACFCC047B8C Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=rgb@redhat.com Received: from madcap2.tricolour.ca (ovpn-112-7.rdu2.redhat.com [10.10.112.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id D45D763750; Wed, 23 Aug 2017 10:13:38 +0000 (UTC) From: Richard Guy Briggs To: linux-security-module@vger.kernel.org, linux-audit@redhat.com Cc: Richard Guy Briggs , Andy Lutomirski , "Serge E. Hallyn" , Kees Cook , James Morris , Eric Paris , Paul Moore , Steve Grubb Subject: [PATCH V3 02/10] capabilities: intuitive names for cap gain status Date: Wed, 23 Aug 2017 06:12:53 -0400 Message-Id: <9e3f99d3c2cbfee24fb3af7ec9b4cf93e4430112.1503459890.git.rgb@redhat.com> In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 23 Aug 2017 10:13:41 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Introduce macros cap_gained, cap_grew, cap_full to make the use of the negation of is_subset() easier to read and analyse. Signed-off-by: Richard Guy Briggs Reviewed-by: Serge Hallyn Acked-by: James Morris --- security/commoncap.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index b7fbf77..6f05ec0 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -513,6 +513,12 @@ void handle_privileged_root(struct linux_binprm *bprm, bool has_cap, bool *effec *effective = true; } +#define cap_gained(field, target, source) \ + !cap_issubset(target->cap_##field, source->cap_##field) +#define cap_grew(target, source, cred) \ + !cap_issubset(cred->cap_##target, cred->cap_##source) +#define cap_full(field, cred) \ + cap_issubset(CAP_FULL_SET, cred->cap_##field) /** * cap_bprm_set_creds - Set up the proposed credentials for execve(). * @bprm: The execution parameters, including the proposed creds @@ -541,10 +547,9 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) handle_privileged_root(bprm, has_cap, &effective, root_uid); /* if we have fs caps, clear dangerous personality flags */ - if (!cap_issubset(new->cap_permitted, old->cap_permitted)) + if (cap_gained(permitted, new, old)) bprm->per_clear |= PER_CLEAR_ON_SETID; - /* Don't let someone trace a set[ug]id/setpcap binary with the revised * credentials unless they have the appropriate permit. * @@ -552,8 +557,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) */ is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid); - if ((is_setid || - !cap_issubset(new->cap_permitted, old->cap_permitted)) && + if ((is_setid || cap_gained(permitted, new, old)) && ((bprm->unsafe & ~LSM_UNSAFE_PTRACE) || !ptracer_capable(current, new->user_ns))) { /* downgrade; they get no more than they had, and maybe less */ @@ -605,8 +609,8 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) * Number 1 above might fail if you don't have a full bset, but I think * that is interesting information to audit. */ - if (!cap_issubset(new->cap_effective, new->cap_ambient)) { - if (!cap_issubset(CAP_FULL_SET, new->cap_effective) || + if (cap_grew(effective, ambient, new)) { + if (!cap_full(effective, new) || !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) || issecure(SECURE_NOROOT)) { ret = audit_log_bprm_fcaps(bprm, new, old);