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/include/net/xfrm.h b/include/net/xfrm.h
index d9509eb..1f217e2 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -662,7 +662,7 @@
 /* Audit Information */
 struct xfrm_audit {
 	u32	secid;
-	uid_t	loginuid;
+	kuid_t	loginuid;
 	u32	sessionid;
 };
 
@@ -681,13 +681,14 @@
 	return audit_buf;
 }
 
-static inline void xfrm_audit_helper_usrinfo(uid_t auid, u32 ses, u32 secid,
+static inline void xfrm_audit_helper_usrinfo(kuid_t auid, u32 ses, u32 secid,
 					     struct audit_buffer *audit_buf)
 {
 	char *secctx;
 	u32 secctx_len;
 
-	audit_log_format(audit_buf, " auid=%u ses=%u", auid, ses);
+	audit_log_format(audit_buf, " auid=%u ses=%u",
+			 from_kuid(&init_user_ns, auid), ses);
 	if (secid != 0 &&
 	    security_secid_to_secctx(secid, &secctx, &secctx_len) == 0) {
 		audit_log_format(audit_buf, " subj=%s", secctx);
@@ -697,13 +698,13 @@
 }
 
 extern void xfrm_audit_policy_add(struct xfrm_policy *xp, int result,
-				  u32 auid, u32 ses, u32 secid);
+				  kuid_t auid, u32 ses, u32 secid);
 extern void xfrm_audit_policy_delete(struct xfrm_policy *xp, int result,
-				  u32 auid, u32 ses, u32 secid);
+				  kuid_t auid, u32 ses, u32 secid);
 extern void xfrm_audit_state_add(struct xfrm_state *x, int result,
-				 u32 auid, u32 ses, u32 secid);
+				 kuid_t auid, u32 ses, u32 secid);
 extern void xfrm_audit_state_delete(struct xfrm_state *x, int result,
-				    u32 auid, u32 ses, u32 secid);
+				    kuid_t auid, u32 ses, u32 secid);
 extern void xfrm_audit_state_replay_overflow(struct xfrm_state *x,
 					     struct sk_buff *skb);
 extern void xfrm_audit_state_replay(struct xfrm_state *x,
@@ -716,22 +717,22 @@
 #else
 
 static inline void xfrm_audit_policy_add(struct xfrm_policy *xp, int result,
-				  u32 auid, u32 ses, u32 secid)
+				  kuid_t auid, u32 ses, u32 secid)
 {
 }
 
 static inline void xfrm_audit_policy_delete(struct xfrm_policy *xp, int result,
-				  u32 auid, u32 ses, u32 secid)
+				  kuid_t auid, u32 ses, u32 secid)
 {
 }
 
 static inline void xfrm_audit_state_add(struct xfrm_state *x, int result,
-				 u32 auid, u32 ses, u32 secid)
+				 kuid_t auid, u32 ses, u32 secid)
 {
 }
 
 static inline void xfrm_audit_state_delete(struct xfrm_state *x, int result,
-				    u32 auid, u32 ses, u32 secid)
+				    kuid_t auid, u32 ses, u32 secid)
 {
 }