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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 C9D68C63697 for ; Tue, 17 Nov 2020 15:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F0EA24199 for ; Tue, 17 Nov 2020 15:09:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729752AbgKQPI6 (ORCPT ); Tue, 17 Nov 2020 10:08:58 -0500 Received: from mail.hallyn.com ([178.63.66.53]:58964 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728830AbgKQPI5 (ORCPT ); Tue, 17 Nov 2020 10:08:57 -0500 Received: by mail.hallyn.com (Postfix, from userid 1001) id D03AC1105; Tue, 17 Nov 2020 09:08:56 -0600 (CST) Date: Tue, 17 Nov 2020 09:08:56 -0600 From: "Serge E. Hallyn" To: lkml Cc: James Morris , =?iso-8859-1?Q?Herv=E9?= Guillemet , "Andrew G. Morgan" , Casey Schaufler Subject: [PATCH] fix namespaced fscaps when !CONFIG_SECURITY Message-ID: <20201117150856.GA12240@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Namespaced file capabilities were introduced in 8db6c34f1dbc . When userspace reads an xattr for a namespaced capability, a virtualized representation of it is returned if the caller is in a user namespace owned by the capability's owning rootid. The function which performs this virtualization was not hooked up if CONFIG_SECURITY=n. Therefore in that case the original xattr was shown instead of the virtualized one. To test this using libcap-bin (*1), $ v=$(mktemp) $ unshare -Ur setcap cap_sys_admin-eip $v $ unshare -Ur setcap -v cap_sys_admin-eip $v /tmp/tmp.lSiIFRvt8Y: OK "setcap -v" verifies the values instead of setting them, and will check whether the rootid value is set. Therefore, with this bug un-fixed, and with CONFIG_SECURITY=n, setcap -v will fail: $ v=$(mktemp) $ unshare -Ur setcap cap_sys_admin=eip $v $ unshare -Ur setcap -v cap_sys_admin=eip $v nsowner[got=1000, want=0],/tmp/tmp.HHDiOOl9fY differs in [] Fix this bug by calling cap_inode_getsecurity() in security_inode_getsecurity() instead of returning -EOPNOTSUPP, when CONFIG_SECURITY=n. *1 - note, if libcap is too old for getcap to have the '-n' option, then use verify-caps instead. Signed-off-by: Serge Hallyn Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1593431 Cc: Hervé Guillemet Cc: Andrew G. Morgan Cc: Casey Schaufler --- include/linux/security.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/security.h b/include/linux/security.h index bc2725491560..39642626a707 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -869,7 +869,7 @@ static inline int security_inode_killpriv(struct dentry *dentry) static inline int security_inode_getsecurity(struct inode *inode, const char *name, void **buffer, bool alloc) { - return -EOPNOTSUPP; + return cap_inode_getsecurity(inode, name, buffer, alloc); } static inline int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags) -- 2.25.1