integrity: PowerVM support for loading third party code signing keys

On secure boot enabled PowerVM LPAR, third party code signing keys are
needed during early boot to verify signed third party modules. These
third party keys are stored in moduledb object in the Platform
KeyStore (PKS).

Load third party code signing keys onto .secondary_trusted_keys keyring.

Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Reviewed-and-tested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

certs/system_keyring.c

@@ -152,6 +152,36 @@ static __init struct key_restriction *get_builtin_and_secondary_restriction(void
 
 	return restriction;
 }
+
+/**
+ * add_to_secondary_keyring - Add to secondary keyring.
+ * @source: Source of key
+ * @data: The blob holding the key
+ * @len: The length of the data blob
+ *
+ * Add a key to the secondary keyring. The key must be vouched for by a key in the builtin,
+ * machine or secondary keyring itself.
+ */
+void __init add_to_secondary_keyring(const char *source, const void *data, size_t len)
+{
+	key_ref_t key;
+	key_perm_t perm;
+
+	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW;
+
+	key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),
+				   "asymmetric",
+				   NULL, data, len, perm,
+				   KEY_ALLOC_NOT_IN_QUOTA);
+	if (IS_ERR(key)) {
+		pr_err("Problem loading X.509 certificate from %s to secondary keyring %ld\n",
+		       source, PTR_ERR(key));
+		return;
+	}
+
+	pr_notice("Loaded X.509 cert '%s'\n", key_ref_to_ptr(key)->description);
+	key_ref_put(key);
+}
 #endif
 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
 void __init set_machine_trusted_keys(struct key *keyring)

include/keys/system_keyring.h

@@ -50,9 +50,13 @@ int restrict_link_by_digsig_builtin_and_secondary(struct key *keyring,
 						  const struct key_type *type,
 						  const union key_payload *payload,
 						  struct key *restriction_key);
+void __init add_to_secondary_keyring(const char *source, const void *data, size_t len);
 #else
 #define restrict_link_by_builtin_and_secondary_trusted restrict_link_by_builtin_trusted
 #define restrict_link_by_digsig_builtin_and_secondary restrict_link_by_digsig_builtin
+static inline void __init add_to_secondary_keyring(const char *source, const void *data, size_t len)
+{
+}
 #endif
 
 #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING

security/integrity/platform_certs/keyring_handler.c

@@ -78,6 +78,14 @@ __init efi_element_handler_t get_handler_for_ca_keys(const efi_guid_t *sig_type)
 	return NULL;
 }
 
+__init efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_type)
+{
+	if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0)
+		return add_to_secondary_keyring;
+
+	return NULL;
+}
+
 /*
  * Return the appropriate handler for particular signature list types found in
  * the UEFI dbx and MokListXRT tables.

security/integrity/platform_certs/keyring_handler.h

@@ -34,6 +34,11 @@ efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type);
  */
 efi_element_handler_t get_handler_for_ca_keys(const efi_guid_t *sig_type);
 
+/*
+ * Return the handler for particular signature list types for code signing keys.
+ */
+efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_type);
+
 /*
  * Return the handler for particular signature list types found in the dbx.
  */

security/integrity/platform_certs/load_powerpc.c

@@ -60,6 +60,7 @@ static int __init load_powerpc_certs(void)
 {
 	void *db = NULL, *dbx = NULL, *data = NULL;
 	void *trustedca;
+	void *moduledb;
 	u64 dsize = 0;
 	u64 offset = 0;
 	int rc = 0;
@@ -137,6 +138,22 @@ static int __init load_powerpc_certs(void)
 		kfree(data);
 	}
 
+	data = get_cert_list("moduledb", 9,  &dsize);
+	if (!data) {
+		pr_info("Couldn't get moduledb list from firmware\n");
+	} else if (IS_ERR(data)) {
+		rc = PTR_ERR(data);
+		pr_err("Error reading moduledb from firmware: %d\n", rc);
+	} else {
+		extract_esl(moduledb, data, dsize, offset);
+
+		rc = parse_efi_signature_list("powerpc:moduledb", moduledb, dsize,
+					      get_handler_for_code_signing_keys);
+		if (rc)
+			pr_err("Couldn't parse moduledb signatures: %d\n", rc);
+		kfree(data);
+	}
+
 	return rc;
 }
 late_initcall(load_powerpc_certs);