From: Seth Forshee <seth.forshee@canonical.com>
Date: Fri, 22 Dec 2017 14:32:35 +0000 (+0100)
Subject: evm: Don't update hmacs in user ns mounts
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=a3a5c966a664dfde0393dd366c2cb916962d164f;p=openwrt%2Fstaging%2Fblogic.git

evm: Don't update hmacs in user ns mounts

The kernel should not calculate new hmacs for mounts done by
non-root users. Update evm_calc_hmac_or_hash() to refuse to
calculate new hmacs for mounts for non-init user namespaces.

Cc: linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: James Morris <james.l.morris@oracle.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Dongsu Park <dongsu@kinvolk.io>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---

diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c
index a46fba322340..facf9cdd577d 100644
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -200,7 +200,8 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
 	int size;
 	bool ima_present = false;
 
-	if (!(inode->i_opflags & IOP_XATTR))
+	if (!(inode->i_opflags & IOP_XATTR) ||
+	    inode->i_sb->s_user_ns != &init_user_ns)
 		return -EOPNOTSUPP;
 
 	desc = init_desc(type);