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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4F7B6C433FE for ; Sat, 5 Feb 2022 06:04:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346867AbiBEGEb (ORCPT ); Sat, 5 Feb 2022 01:04:31 -0500 Received: from mail.hallyn.com ([178.63.66.53]:39068 "EHLO mail.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344783AbiBEGEa (ORCPT ); Sat, 5 Feb 2022 01:04:30 -0500 Received: by mail.hallyn.com (Postfix, from userid 1001) id 136E47E4; Fri, 4 Feb 2022 23:58:27 -0600 (CST) Date: Fri, 4 Feb 2022 23:58:27 -0600 From: "Serge E. Hallyn" To: Stefan Berger Cc: linux-integrity@vger.kernel.org, zohar@linux.ibm.com, serge@hallyn.com, christian.brauner@ubuntu.com, containers@lists.linux.dev, dmitry.kasatkin@gmail.com, ebiederm@xmission.com, krzysztof.struczynski@huawei.com, roberto.sassu@huawei.com, mpeters@redhat.com, lhinds@redhat.com, lsturman@redhat.com, puiterwi@redhat.com, jejb@linux.ibm.com, jamjoom@us.ibm.com, linux-kernel@vger.kernel.org, paul@paul-moore.com, rgb@redhat.com, linux-security-module@vger.kernel.org, jmorris@namei.org, Denis Semakin Subject: Re: [PATCH v10 12/27] ima: Define mac_admin_ns_capable() as a wrapper for ns_capable() Message-ID: <20220205055826.GA15072@mail.hallyn.com> References: <20220201203735.164593-1-stefanb@linux.ibm.com> <20220201203735.164593-13-stefanb@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220201203735.164593-13-stefanb@linux.ibm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Tue, Feb 01, 2022 at 03:37:20PM -0500, Stefan Berger wrote: > Define mac_admin_ns_capable() as a wrapper for the combined ns_capable() > checks on CAP_MAC_ADMIN and CAP_SYS_ADMIN in a user namespace. Return > true on the check if either capability or both are available. > > Use mac_admin_ns_capable() in place of capable(SYS_ADMIN). This will allow > an IMA namespace to read the policy with only CAP_MAC_ADMIN, which has > less privileges than CAP_SYS_ADMIN. > > Signed-off-by: Denis Semakin > Signed-off-by: Stefan Berger > --- > include/linux/capability.h | 6 ++++++ > security/integrity/ima/ima.h | 6 ++++++ > security/integrity/ima/ima_fs.c | 5 ++++- > 3 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/include/linux/capability.h b/include/linux/capability.h > index 65efb74c3585..991579178f32 100644 > --- a/include/linux/capability.h > +++ b/include/linux/capability.h > @@ -270,6 +270,12 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns) > ns_capable(ns, CAP_SYS_ADMIN); > } > > +static inline bool mac_admin_ns_capable(struct user_namespace *ns) > +{ > + return ns_capable(ns, CAP_MAC_ADMIN) || > + ns_capable(ns, CAP_SYS_ADMIN); Do you care about audit warnings? If the task has CAP_SYS_ADMIN but not CAP_MAC_ADMIN, is it desirable that selinux_capable() will audit the CAP_MAC_ADMIN failure? > +} > + > /* audit system wants to get cap info from files as well */ > int get_vfs_caps_from_disk(struct user_namespace *mnt_userns, > const struct dentry *dentry, > diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h > index fb6bd054d899..0057b1fd6c18 100644 > --- a/security/integrity/ima/ima.h > +++ b/security/integrity/ima/ima.h > @@ -487,4 +487,10 @@ static inline int ima_filter_rule_match(u32 secid, u32 field, u32 op, > #define POLICY_FILE_FLAGS S_IWUSR > #endif /* CONFIG_IMA_READ_POLICY */ > > +static inline > +struct user_namespace *ima_user_ns_from_file(const struct file *filp) > +{ > + return file_inode(filp)->i_sb->s_user_ns; > +} > + > #endif /* __LINUX_IMA_H */ > diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c > index 89d3113ceda1..c41aa61b7393 100644 > --- a/security/integrity/ima/ima_fs.c > +++ b/security/integrity/ima/ima_fs.c > @@ -377,6 +377,9 @@ static const struct seq_operations ima_policy_seqops = { > */ > static int ima_open_policy(struct inode *inode, struct file *filp) > { > +#ifdef CONFIG_IMA_READ_POLICY > + struct user_namespace *user_ns = ima_user_ns_from_file(filp); > +#endif > struct ima_namespace *ns = &init_ima_ns; > > if (!(filp->f_flags & O_WRONLY)) { > @@ -385,7 +388,7 @@ static int ima_open_policy(struct inode *inode, struct file *filp) > #else > if ((filp->f_flags & O_ACCMODE) != O_RDONLY) > return -EACCES; > - if (!capable(CAP_SYS_ADMIN)) > + if (!mac_admin_ns_capable(user_ns)) > return -EPERM; > return seq_open(filp, &ima_policy_seqops); > #endif > -- > 2.31.1