KEYS: store reference to machine keyring

Expose the .machine keyring created in integrity code by adding
a reference.  Store a reference to the machine keyring in
system keyring code. The system keyring code needs this to complete
the keyring link to the machine keyring.
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

certs/system_keyring.c

@@ -22,6 +22,9 @@ static struct key *builtin_trusted_keys;
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 static struct key *secondary_trusted_keys;
 #endif
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+static struct key *machine_trusted_keys;
+#endif
 #ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
 static struct key *platform_trusted_keys;
 #endif
@@ -91,6 +94,12 @@ static __init struct key_restriction *get_builtin_and_secondary_restriction(void
 	return restriction;
 }
 #endif
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+void __init set_machine_trusted_keys(struct key *keyring)
+{
+	machine_trusted_keys = keyring;
+}
+#endif
 
 /*
  * Create the trusted keyrings

include/keys/system_keyring.h

@@ -38,6 +38,14 @@ extern int restrict_link_by_builtin_and_secondary_trusted(
 #define restrict_link_by_builtin_and_secondary_trusted restrict_link_by_builtin_trusted
 #endif
 
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+extern void __init set_machine_trusted_keys(struct key *keyring);
+#else
+static inline void __init set_machine_trusted_keys(struct key *keyring)
+{
+}
+#endif
+
 extern struct pkcs7_message *pkcs7;
 #ifdef CONFIG_SYSTEM_BLACKLIST_KEYRING
 extern int mark_hash_blacklisted(const char *hash);

security/integrity/digsig.c

@@ -112,6 +112,8 @@ static int __init __integrity_init_keyring(const unsigned int id,
 	} else {
 		if (id == INTEGRITY_KEYRING_PLATFORM)
 			set_platform_trusted_keys(keyring[id]);
+		if (id == INTEGRITY_KEYRING_MACHINE)
+			set_machine_trusted_keys(keyring[id]);
 		if (id == INTEGRITY_KEYRING_IMA)
 			load_module_cert(keyring[id]);
 	}