integrity: define '.evm' as a builtin 'trusted' keyring

Require all keys added to the EVM keyring be signed by an
existing trusted key on the system trusted keyring.

This patch also switches IMA to use integrity_init_keyring().

Changes in v3:
* Added 'init_keyring' config based variable to skip initializing
  keyring instead of using  __integrity_init_keyring() wrapper.
* Added dependency back to CONFIG_IMA_TRUSTED_KEYRING

Changes in v2:
* Replace CONFIG_EVM_TRUSTED_KEYRING with IMA and EVM common
  CONFIG_INTEGRITY_TRUSTED_KEYRING configuration option
* Deprecate CONFIG_IMA_TRUSTED_KEYRING but keep it for config
  file compatibility. (Mimi Zohar)

Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

Author: Dmitry Kasatkin

security/integrity/Kconfig

@@ -41,6 +41,17 @@ config INTEGRITY_ASYMMETRIC_KEYS
 	  This option enables digital signature verification using
 	  asymmetric keys.
 
+config INTEGRITY_TRUSTED_KEYRING
+	bool "Require all keys on the integrity keyrings be signed"
+	depends on SYSTEM_TRUSTED_KEYRING
+	depends on INTEGRITY_ASYMMETRIC_KEYS
+	select KEYS_DEBUG_PROC_KEYS
+	default y
+	help
+	   This option requires that all keys added to the .ima and
+	   .evm keyrings be signed by a key on the system trusted
+	   keyring.
+
 config INTEGRITY_AUDIT
 	bool "Enables integrity auditing support "
 	depends on AUDIT

security/integrity/digsig.c

@@ -24,15 +24,22 @@
 static struct key *keyring[INTEGRITY_KEYRING_MAX];
 
 static const char *keyring_name[INTEGRITY_KEYRING_MAX] = {
+#ifndef CONFIG_INTEGRITY_TRUSTED_KEYRING
 	"_evm",
-	"_module",
-#ifndef CONFIG_IMA_TRUSTED_KEYRING
 	"_ima",
 #else
+	".evm",
 	".ima",
 #endif
+	"_module",
 };
 
+#ifdef CONFIG_INTEGRITY_TRUSTED_KEYRING
+static bool init_keyring __initdata = true;
+#else
+static bool init_keyring __initdata;
+#endif
+
 int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
 			    const char *digest, int digestlen)
 {
@@ -68,6 +75,9 @@ int __init integrity_init_keyring(const unsigned int id)
 	const struct cred *cred = current_cred();
 	int err = 0;
 
+	if (!init_keyring)
+		return 0;
+
 	keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0),
 				    KGIDT_INIT(0), cred,
 				    ((KEY_POS_ALL & ~KEY_POS_SETATTR) |

security/integrity/evm/evm_main.c

@@ -478,15 +478,17 @@ static int __init init_evm(void)
 
 	evm_init_config();
 
+	error = integrity_init_keyring(INTEGRITY_KEYRING_EVM);
+	if (error)
+		return error;
+
 	error = evm_init_secfs();
 	if (error < 0) {
 		pr_info("Error registering secfs\n");
-		goto err;
+		return error;
 	}
 
 	return 0;
-err:
-	return error;
 }
 
 /*

security/integrity/ima/Kconfig

@@ -123,14 +123,17 @@ config IMA_APPRAISE
 	  If unsure, say N.
 
 config IMA_TRUSTED_KEYRING
-	bool "Require all keys on the .ima keyring be signed"
+	bool "Require all keys on the .ima keyring be signed (deprecated)"
 	depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING
 	depends on INTEGRITY_ASYMMETRIC_KEYS
+	select INTEGRITY_TRUSTED_KEYRING
 	default y
 	help
 	   This option requires that all keys added to the .ima
 	   keyring be signed by a key on the system trusted keyring.
 
+	   This option is deprecated in favor of INTEGRITY_TRUSTED_KEYRING
+
 config IMA_LOAD_X509
 	bool "Load X509 certificate onto the '.ima' trusted keyring"
 	depends on IMA_TRUSTED_KEYRING

security/integrity/ima/ima.h

@@ -251,16 +251,4 @@ static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
 	return -EINVAL;
 }
 #endif /* CONFIG_IMA_LSM_RULES */
-
-#ifdef CONFIG_IMA_TRUSTED_KEYRING
-static inline int ima_init_keyring(const unsigned int id)
-{
-	return integrity_init_keyring(id);
-}
-#else
-static inline int ima_init_keyring(const unsigned int id)
-{
-	return 0;
-}
-#endif /* CONFIG_IMA_TRUSTED_KEYRING */
 #endif

security/integrity/ima/ima_init.c

@@ -116,7 +116,7 @@ int __init ima_init(void)
 	if (!ima_used_chip)
 		pr_info("No TPM chip found, activating TPM-bypass!\n");
 
-	rc = ima_init_keyring(INTEGRITY_KEYRING_IMA);
+	rc = integrity_init_keyring(INTEGRITY_KEYRING_IMA);
 	if (rc)
 		return rc;
 

security/integrity/integrity.h

@@ -125,8 +125,8 @@ int integrity_kernel_read(struct file *file, loff_t offset,
 int __init integrity_read_file(const char *path, char **data);
 
 #define INTEGRITY_KEYRING_EVM		0
-#define INTEGRITY_KEYRING_MODULE	1
-#define INTEGRITY_KEYRING_IMA		2
+#define INTEGRITY_KEYRING_IMA		1
+#define INTEGRITY_KEYRING_MODULE	2
 #define INTEGRITY_KEYRING_MAX		3
 
 #ifdef CONFIG_INTEGRITY_SIGNATURE
@@ -149,7 +149,6 @@ static inline int integrity_init_keyring(const unsigned int id)
 {
 	return 0;
 }
-
 #endif /* CONFIG_INTEGRITY_SIGNATURE */
 
 #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS