keys: fix trusted/encrypted keys sparse rcu_assign_pointer messages

Define rcu_assign_keypointer(), which uses the key payload.rcudata instead
of payload.data, to resolve the CONFIG_SPARSE_RCU_POINTER message:
"incompatible types in comparison expression (different address spaces)"

Replace the rcu_assign_pointer() calls in encrypted/trusted keys with
rcu_assign_keypointer().

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

include/linux/key.h

@@ -293,6 +293,9 @@ static inline bool key_is_instantiated(const struct key *key)
 	(rcu_dereference_protected((KEY)->payload.rcudata,		\
 				   rwsem_is_locked(&((struct key *)(KEY))->sem)))
 
+#define rcu_assign_keypointer(KEY, PAYLOAD)				\
+	(rcu_assign_pointer((KEY)->payload.rcudata, PAYLOAD))
+
 #ifdef CONFIG_SYSCTL
 extern ctl_table key_sysctls[];
 #endif

security/keys/encrypted-keys/encrypted.c

@@ -810,7 +810,7 @@ static int encrypted_instantiate(struct key *key, const void *data,
 		goto out;
 	}
 
-	rcu_assign_pointer(key->payload.data, epayload);
+	rcu_assign_keypointer(key, epayload);
 out:
 	kfree(datablob);
 	return ret;
@@ -874,7 +874,7 @@ static int encrypted_update(struct key *key, const void *data, size_t datalen)
 	memcpy(new_epayload->payload_data, epayload->payload_data,
 	       epayload->payload_datalen);
 
-	rcu_assign_pointer(key->payload.data, new_epayload);
+	rcu_assign_keypointer(key, new_epayload);
 	call_rcu(&epayload->rcu, encrypted_rcu_free);
 out:
 	kfree(buf);

security/keys/encrypted-keys/masterkey_trusted.c

@@ -18,6 +18,8 @@
 #include <linux/module.h>
 #include <linux/err.h>
 #include <keys/trusted-type.h>
+#include <keys/encrypted-type.h>
+#include "encrypted.h"
 
 /*
  * request_trusted_key - request the trusted key

security/keys/trusted.c

@@ -993,7 +993,7 @@ out:
 	kfree(datablob);
 	kfree(options);
 	if (!ret)
-		rcu_assign_pointer(key->payload.data, payload);
+		rcu_assign_keypointer(key, payload);
 	else
 		kfree(payload);
 	return ret;
@@ -1067,7 +1067,7 @@ static int trusted_update(struct key *key, const void *data, size_t datalen)
 			goto out;
 		}
 	}
-	rcu_assign_pointer(key->payload.data, new_p);
+	rcu_assign_keypointer(key, new_p);
 	call_rcu(&p->rcu, trusted_rcu_free);
 out:
 	kfree(datablob);