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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 A6D3CC6379F for ; Fri, 20 Nov 2020 03:17:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80C4322256 for ; Fri, 20 Nov 2020 03:17:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727220AbgKTDRF (ORCPT ); Thu, 19 Nov 2020 22:17:05 -0500 Received: from namei.org ([65.99.196.166]:54356 "EHLO namei.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726281AbgKTDRE (ORCPT ); Thu, 19 Nov 2020 22:17:04 -0500 Received: from localhost (localhost [127.0.0.1]) by namei.org (8.14.4/8.14.4) with ESMTP id 0AK3GrqJ021162; Fri, 20 Nov 2020 03:16:53 GMT Date: Fri, 20 Nov 2020 14:16:53 +1100 (AEDT) From: James Morris To: "Serge E. Hallyn" cc: lkml , =?ISO-8859-15?Q?Herv=E9_Guillemet?= , "Andrew G. Morgan" , Casey Schaufler , linux-security-module@vger.kernel.org Subject: Re: [PATCH] fix namespaced fscaps when !CONFIG_SECURITY In-Reply-To: <20201117150856.GA12240@mail.hallyn.com> Message-ID: References: <20201117150856.GA12240@mail.hallyn.com> User-Agent: Alpine 2.21 (LRH 202 2017-01-01) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="1665246916-1261770800-1605842213=:20300" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --1665246916-1261770800-1605842213=:20300 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT [Adding LSM list] On Tue, 17 Nov 2020, Serge E. Hallyn wrote: > 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) > -- James Morris --1665246916-1261770800-1605842213=:20300--