NetLabel: Allow passing the LSM domain as a shared pointer

Smack doesn't have the need to create a private copy of the LSM "domain" when
setting NetLabel security attributes like SELinux, however, the current
NetLabel code requires a private copy of the LSM "domain".  This patches fixes
that by letting the LSM determine how it wants to pass the domain value.

 * NETLBL_SECATTR_DOMAIN_CPY
   The current behavior, NetLabel assumes that the domain value is a copy and
   frees it when done

 * NETLBL_SECATTR_DOMAIN
   New, Smack-friendly behavior, NetLabel assumes that the domain value is a
   reference to a string managed by the LSM and does not free it when done

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index f374186..47295ac 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2649,7 +2649,7 @@
 		goto netlbl_sid_to_secattr_failure;
 	secattr->domain = kstrdup(policydb.p_type_val_to_name[ctx->type - 1],
 				  GFP_ATOMIC);
-	secattr->flags |= NETLBL_SECATTR_DOMAIN;
+	secattr->flags |= NETLBL_SECATTR_DOMAIN_CPY;
 	mls_export_netlbl_lvl(ctx, secattr);
 	rc = mls_export_netlbl_cat(ctx, secattr);
 	if (rc != 0)