userns: Convert the audit loginuid  to be a kuid

Always store audit loginuids in type kuid_t.

Print loginuids by converting them into uids in the appropriate user
namespace, and then printing the resulting uid.

Modify audit_get_loginuid to return a kuid_t.

Modify audit_set_loginuid to take a kuid_t.

Modify /proc/<pid>/loginuid on read to convert the loginuid into the
user namespace of the opener of the file.

Modify /proc/<pid>/loginud on write to convert the loginuid
rom the user namespace of the opener of the file.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Paul Moore <paul@paul-moore.com> ?
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index e75d8e4..9ea55db 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -575,7 +575,7 @@
 	struct xfrm_state *x;
 	int err;
 	struct km_event c;
-	uid_t loginuid = audit_get_loginuid(current);
+	kuid_t loginuid = audit_get_loginuid(current);
 	u32 sessionid = audit_get_sessionid(current);
 	u32 sid;
 
@@ -654,7 +654,7 @@
 	int err = -ESRCH;
 	struct km_event c;
 	struct xfrm_usersa_id *p = nlmsg_data(nlh);
-	uid_t loginuid = audit_get_loginuid(current);
+	kuid_t loginuid = audit_get_loginuid(current);
 	u32 sessionid = audit_get_sessionid(current);
 	u32 sid;
 
@@ -1369,7 +1369,7 @@
 	struct km_event c;
 	int err;
 	int excl;
-	uid_t loginuid = audit_get_loginuid(current);
+	kuid_t loginuid = audit_get_loginuid(current);
 	u32 sessionid = audit_get_sessionid(current);
 	u32 sid;
 
@@ -1624,7 +1624,7 @@
 					    NETLINK_CB(skb).pid);
 		}
 	} else {
-		uid_t loginuid = audit_get_loginuid(current);
+		kuid_t loginuid = audit_get_loginuid(current);
 		u32 sessionid = audit_get_sessionid(current);
 		u32 sid;
 
@@ -1918,7 +1918,7 @@
 
 	err = 0;
 	if (up->hard) {
-		uid_t loginuid = audit_get_loginuid(current);
+		kuid_t loginuid = audit_get_loginuid(current);
 		u32 sessionid = audit_get_sessionid(current);
 		u32 sid;
 
@@ -1961,7 +1961,7 @@
 	km_state_expired(x, ue->hard, current->pid);
 
 	if (ue->hard) {
-		uid_t loginuid = audit_get_loginuid(current);
+		kuid_t loginuid = audit_get_loginuid(current);
 		u32 sessionid = audit_get_sessionid(current);
 		u32 sid;