Replace magic for trusting the secondary keyring with #define

Replace the use of a magic number that indicates that verify_*_signature()
should use the secondary keyring with a symbol.
Signed-off-by: NYannik Sembritzki <yannik@sembritzki.me>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Cc: keyrings@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

certs/system_keyring.c

@@ -15,6 +15,7 @@
 #include <linux/cred.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/verification.h>
 #include <keys/asymmetric-type.h>
 #include <keys/system_keyring.h>
 #include <crypto/pkcs7.h>
@@ -230,7 +231,7 @@ int verify_pkcs7_signature(const void *data, size_t len,
 
 	if (!trusted_keys) {
 		trusted_keys = builtin_trusted_keys;
-	} else if (trusted_keys == (void *)1UL) {
+	} else if (trusted_keys == VERIFY_USE_SECONDARY_KEYRING) {
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 		trusted_keys = secondary_trusted_keys;
 #else

crypto/asymmetric_keys/pkcs7_key_type.c

@@ -63,7 +63,7 @@ static int pkcs7_preparse(struct key_preparsed_payload *prep)
 
 	return verify_pkcs7_signature(NULL, 0,
 				      prep->data, prep->datalen,
-				      (void *)1UL, usage,
+				      VERIFY_USE_SECONDARY_KEYRING, usage,
 				      pkcs7_view_content, prep);
 }
 

include/linux/verification.h

@@ -12,6 +12,12 @@
 #ifndef _LINUX_VERIFICATION_H
 #define _LINUX_VERIFICATION_H
 
+/*
+ * Indicate that both builtin trusted keys and secondary trusted keys
+ * should be used.
+ */
+#define VERIFY_USE_SECONDARY_KEYRING ((struct key *)1UL)
+
 /*
  * The use to which an asymmetric key is being put.
  */