From mboxrd@z Thu Jan 1 00:00:00 1970 From: Seth Forshee Subject: [PATCH 6/7] selinux: Ignore security labels on user namespace mounts Date: Wed, 15 Jul 2015 14:46:07 -0500 Message-ID: <1436989569-69582-7-git-send-email-seth.forshee@canonical.com> References: <1436989569-69582-1-git-send-email-seth.forshee@canonical.com> Cc: Serge Hallyn , Andy Lutomirski , Seth Forshee , linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, linux-kernel@vger.kernel.org, James Morris , "Serge E. Hallyn" To: "Eric W. Biederman" , Alexander Viro , Paul Moore , Stephen Smalley , Eric Paris Return-path: In-Reply-To: <1436989569-69582-1-git-send-email-seth.forshee@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Unprivileged users should not be able to supply security labels in filesystems, nor should they be able to supply security contexts in unprivileged mounts. For any mount where s_user_ns is not init_user_ns, force the use of SECURITY_FS_USE_NONE behavior and return EPERM if any contexts are supplied in the mount options. Signed-off-by: Seth Forshee --- security/selinux/hooks.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 459e71ddbc9d..eeb71e45ab82 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -732,6 +732,19 @@ static int selinux_set_mnt_opts(struct super_block *sb, !strcmp(sb->s_type->name, "pstore")) sbsec->flags |= SE_SBGENFS; + /* + * If this is a user namespace mount, no contexts are allowed + * on the command line and security labels mus be ignored. + */ + if (sb->s_user_ns != &init_user_ns) { + if (context_sid || fscontext_sid || rootcontext_sid || + defcontext_sid) + return -EPERM; + sbsec->behavior = SECURITY_FS_USE_NONE; + goto out_set_opts; + } + + if (!sbsec->behavior) { /* * Determine the labeling behavior to use for this @@ -813,6 +826,7 @@ 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