Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:54785 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938983AbdEYVH4 (ORCPT ); Thu, 25 May 2017 17:07:56 -0400 From: Scott Mayhew To: selinux@tycho.nsa.gov, linux-nfs@vger.kernel.org Cc: Paul Moore , Stephen Smalley , Eric Paris , Trond Myklebust , "J . Bruce Fields" Subject: [PATCH RFC 1/2] selinux: allow SECURITY_LSM_NATIVE_LABELS to be set on an already initialized superblock Date: Thu, 25 May 2017 17:07:53 -0400 Message-Id: <20170525210754.24265-2-smayhew@redhat.com> In-Reply-To: <20170525210754.24265-1-smayhew@redhat.com> References: <20170404232646.GB24146@parsley.fieldses.org> <20170525210754.24265-1-smayhew@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: When an NFSv4 client performs a mount operation, it first mounts the NFSv4 root and then does path walk to the exported path and performs a submount on that, cloning the security mount options from the root's superblock to the submount's superblock in the process. Unless the NFS server has an explicit fsid=0 export with the "security_label" option, the NFSv4 root superblock will not have SBLABEL_MNT set, and neither will the submount superblock after cloning the security mount options. As a result, setxattr's of security labels over NFSv4.2 will fail. Allowing the NFSv4 client to override the SECURITY_LSM_NATIVE_LABELS flag on an initialized superblock will ensure that SBLABEL_MNT is set when the client traverses from an exported path without the "security_label" option to one with the "security_label" option. Signed-off-by: Scott Mayhew --- security/selinux/hooks.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index e67a526..366ab86 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -730,7 +730,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, * will be used for both mounts) */ if ((sbsec->flags & SE_SBINITIALIZED) && (sb->s_type->fs_flags & FS_BINARY_MOUNTDATA) - && (num_opts == 0)) + && (num_opts == 0) && !(kern_flags & SECURITY_LSM_NATIVE_LABELS)) goto out; root_isec = backing_inode_security_novalidate(root); @@ -797,7 +797,7 @@ static int selinux_set_mnt_opts(struct super_block *sb, } } - if (sbsec->flags & SE_SBINITIALIZED) { + if (sbsec->flags & SE_SBINITIALIZED && !(kern_flags & SECURITY_LSM_NATIVE_LABELS)) { /* previously mounted with options, but not on this attempt? */ if ((sbsec->flags & SE_MNTMASK) && !num_opts) goto out_double_mount; -- 2.9.3