userns: Add user namespace support to IMA

Use kuid's in the IMA rules.

When reporting the current uid in audit logs use from_kuid
to get a usable value.

Cc: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/security/integrity/ima/ima_audit.c b/security/integrity/ima/ima_audit.c
index 7a57f67..c586faa 100644
--- a/security/integrity/ima/ima_audit.c
+++ b/security/integrity/ima/ima_audit.c
@@ -39,8 +39,9 @@
 
 	ab = audit_log_start(current->audit_context, GFP_KERNEL, audit_msgno);
 	audit_log_format(ab, "pid=%d uid=%u auid=%u ses=%u",
-			 current->pid, current_cred()->uid,
-			 audit_get_loginuid(current),
+			 current->pid,
+			 from_kuid(&init_user_ns, current_cred()->uid),
+			 from_kuid(&init_user_ns, audit_get_loginuid(current)),
 			 audit_get_sessionid(current));
 	audit_log_task_context(ab);
 	audit_log_format(ab, " op=");