Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933362AbbHJVGP (ORCPT ); Mon, 10 Aug 2015 17:06:15 -0400 Received: from mail-ig0-f178.google.com ([209.85.213.178]:33397 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933261AbbHJVFr (ORCPT ); Mon, 10 Aug 2015 17:05:47 -0400 From: Seth Forshee To: "Eric W. Biederman" , Alexander Viro , Paul Moore , Stephen Smalley , Eric Paris Cc: Serge Hallyn , Andy Lutomirski , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, Seth Forshee , James Morris , "Serge E. Hallyn" Subject: [PATCH v2 7/7] selinux: Add support for unprivileged mounts from user namespaces Date: Mon, 10 Aug 2015 16:05:18 -0500 Message-Id: <1439240719-46850-8-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1439240719-46850-1-git-send-email-seth.forshee@canonical.com> References: <1439240719-46850-1-git-send-email-seth.forshee@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2087 Lines: 64 Security labels from unprivileged mounts in user namespaces must be ignored. Force superblocks from user namespaces whose labeling behavior is to use xattrs to use mountpoint labeling instead. For the mountpoint label, default to converting the current task context into a form suitable for file objects, but also allow the policy writer to specify a different label through policy transition rules. Pieced together from code snippets provided by Stephen Smalley. Signed-off-by: Seth Forshee --- security/selinux/hooks.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 459e71ddbc9d..242dac0b8b24 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -745,6 +745,28 @@ static int selinux_set_mnt_opts(struct super_block *sb, goto out; } } + + /* + * If this is a user namespace mount, no contexts are allowed + * on the command line and security labels must be ignored. + */ + if (sb->s_user_ns != &init_user_ns) { + if (context_sid || fscontext_sid || rootcontext_sid || + defcontext_sid) { + rc = -EACCES; + goto out; + } + if (sbsec->behavior == SECURITY_FS_USE_XATTR) { + sbsec->behavior = SECURITY_FS_USE_MNTPOINT; + rc = security_transition_sid(current_sid(), current_sid(), + SECCLASS_FILE, NULL, + &sbsec->mntpoint_sid); + if (rc) + goto out; + } + goto out_set_opts; + } + /* sets the context of the superblock for the fs being mounted. */ if (fscontext_sid) { rc = may_context_mount_sb_relabel(fscontext_sid, sbsec, cred); @@ -813,6 +835,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, sbsec->def_sid = defcontext_sid; } +out_set_opts: rc = sb_finish_set_opts(sb); out: mutex_unlock(&sbsec->lock); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/