From patchwork Tue Sep 5 06:46:02 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: 9937891 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 BE5FC603F9 for ; Tue, 5 Sep 2017 06:47:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B14DE2889F for ; Tue, 5 Sep 2017 06:47:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A6555288A2; Tue, 5 Sep 2017 06:47:24 +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 EE4A3288A6 for ; Tue, 5 Sep 2017 06:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750926AbdIEGqv (ORCPT ); Tue, 5 Sep 2017 02:46:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41272 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750878AbdIEGqv (ORCPT ); Tue, 5 Sep 2017 02:46:51 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id F3121C01419F; Tue, 5 Sep 2017 06:46:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com F3121C01419F 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-112-9.rdu2.redhat.com [10.10.112.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2D505C4525; Tue, 5 Sep 2017 06:46:47 +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 V4 02/10] capabilities: intuitive names for cap gain status Date: Tue, 5 Sep 2017 02:46:02 -0400 Message-Id: In-Reply-To: References: In-Reply-To: References: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Tue, 05 Sep 2017 06:46:51 +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 Acked-by: Kees Cook --- security/commoncap.c | 18 +++++++++++------- 1 files changed, 11 insertions(+), 7 deletions(-) diff --git a/security/commoncap.c b/security/commoncap.c index 927fe93..cf6e2b0 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -505,6 +505,12 @@ static void handle_privileged_root(struct linux_binprm *bprm, bool has_cap, *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 @@ -533,10 +539,9 @@ 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. * @@ -544,8 +549,7 @@ 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 */ @@ -595,8 +599,8 @@ 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); @@ -616,7 +620,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm) bprm->cap_elevated = 1; } else if (!uid_eq(new->uid, root_uid)) { if (effective || - !cap_issubset(new->cap_permitted, new->cap_ambient)) + __cap_grew(permitted, ambient, new)) bprm->cap_elevated = 1; }