ima: enable loading of build time generated key on .ima keyring

The kernel currently only loads the kernel module signing key onto the
builtin trusted keyring. Load the module signing key onto the IMA keyring
as well.

Signed-off-by: Nayna Jain <[e-mail]>
Acked-by: Stefan Berger <[e-mail]>
Signed-off-by: Mimi Zohar <[e-mail]>

certs/system_certificates.S

···
 	.globl system_certificate_list
 system_certificate_list:
 __cert_list_start:
-#ifdef CONFIG_MODULE_SIG
+__module_cert_start:
+#if defined(CONFIG_MODULE_SIG) || defined(CONFIG_IMA_APPRAISE_MODSIG)
 	.incbin "certs/signing_key.x509"
 #endif
+__module_cert_end:
 	.incbin "certs/x509_certificate_list"
 __cert_list_end:
 
···
 	.quad __cert_list_end - __cert_list_start
 #else
 	.long __cert_list_end - __cert_list_start
+#endif
+
+	.align 8
+	.globl module_cert_size
+module_cert_size:
+#ifdef CONFIG_64BIT
+	.quad __module_cert_end - __module_cert_start
+#else
+	.long __module_cert_end - __module_cert_start
 #endif

certs/system_keyring.c

···
 
 extern __initconst const u8 system_certificate_list[];
 extern __initconst const unsigned long system_certificate_list_size;
+extern __initconst const unsigned long module_cert_size;
 
 /**
  * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
···
  */
 device_initcall(system_trusted_keyring_init);
 
-/*
- * Load the compiled-in list of X.509 certificates.
- */
-static __init int load_system_certificate_list(void)
+static __init int load_cert(const u8 *p, const u8 *end, struct key *keyring)
 {
 	key_ref_t key;
-	const u8 *p, *end;
 	size_t plen;
 
-	pr_notice("Loading compiled-in X.509 certificates\n");
-
-	p = system_certificate_list;
-	end = p + system_certificate_list_size;
 	while (p < end) {
 		/* Each cert begins with an ASN.1 SEQUENCE tag and must be more
 		 * than 256 bytes in size.
···
 		if (plen > end - p)
 			goto dodgy_cert;
 
-		key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
+		key = key_create_or_update(make_key_ref(keyring, 1),
 					   "asymmetric",
 					   NULL,
 					   p,
···
 dodgy_cert:
 	pr_err("Problem parsing in-kernel X.509 certificate list\n");
 	return 0;
+}
+
+__init int load_module_cert(struct key *keyring)
+{
+	const u8 *p, *end;
+
+	if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG))
+		return 0;
+
+	pr_notice("Loading compiled-in module X.509 certificates\n");
+
+	p = system_certificate_list;
+	end = p + module_cert_size;
+
+	return load_cert(p, end, keyring);
+}
+
+/*
+ * Load the compiled-in list of X.509 certificates.
+ */
+static __init int load_system_certificate_list(void)
+{
+	const u8 *p, *end;
+	unsigned long size;
+
+	pr_notice("Loading compiled-in X.509 certificates\n");
+
+#ifdef CONFIG_MODULE_SIG
+	p = system_certificate_list;
+	size = system_certificate_list_size;
+#else
+	p = system_certificate_list + module_cert_size;
+	size = system_certificate_list_size - module_cert_size;
+#endif
+
+	end = p + size;
+	return load_cert(p, end, builtin_trusted_keys);
 }
 late_initcall(load_system_certificate_list);
 

include/keys/system_keyring.h

···
 					    const struct key_type *type,
 					    const union key_payload *payload,
 					    struct key *restriction_key);
+extern __init int load_module_cert(struct key *keyring);
 
 #else
 #define restrict_link_by_builtin_trusted restrict_link_reject
+
+static inline __init int load_module_cert(struct key *keyring)
+{
+	return 0;
+}
+
 #endif
 
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING

security/integrity/digsig.c

···
 	} else {
 		if (id == INTEGRITY_KEYRING_PLATFORM)
 			set_platform_trusted_keys(keyring[id]);
+		if (id == INTEGRITY_KEYRING_IMA)
+			load_module_cert(keyring[id]);
 	}
 
 	return err;