Merge: Allow to enroll custom IMA keys

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2596

Bugzilla: https://bugzilla.redhat.com/2055205

This patch set allows enrolling customer keys for IMA signatures by enabling the .machine keyring for UEFI-based systems. Users will add their customer IMA CA certifciates/keys to the MOK list and the keys will eventually be loaded to the .machine keyring which is linked the the .secondary_trusted_keys keyring.

Signed-off-by: Coiby Xu <coxu@redhat.com>

Approved-by: Jerry Snitselaar <jsnitsel@redhat.com>
Approved-by: Vladis Dronov <vdronov@redhat.com>

Signed-off-by: Jan Stancek <jstancek@redhat.com>

certs/system_keyring.c

@@ -21,6 +21,9 @@ 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
@@ -30,7 +33,11 @@ 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
+ * restrict_link_by_builtin_trusted - Restrict keyring addition by built-in CA
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restriction_key: A ring of keys that can be used to vouch for the new cert.
  *
  * Restrict the addition of keys into a keyring based on the key-to-be-added
  * being vouched for by a key in the built in system keyring.
@@ -44,10 +51,34 @@ int restrict_link_by_builtin_trusted(struct key *dest_keyring,
 					  builtin_trusted_keys);
 }
 
+/**
+ * restrict_link_by_digsig_builtin - Restrict digitalSignature key additions by the built-in keyring
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restriction_key: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in the built in system keyring. The new key
+ * must have the digitalSignature usage field set.
+ */
+int restrict_link_by_digsig_builtin(struct key *dest_keyring,
+				    const struct key_type *type,
+				    const union key_payload *payload,
+				    struct key *restriction_key)
+{
+	return restrict_link_by_digsig(dest_keyring, type, payload,
+				       builtin_trusted_keys);
+}
+
 #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
 /**
  * restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
- *   addition by both builtin and secondary keyrings
+ *   addition by both built-in and secondary keyrings.
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restrict_key: A ring of keys that can be used to vouch for the new cert.
  *
  * Restrict the addition of keys into a keyring based on the key-to-be-added
  * being vouched for by a key in either the built-in or the secondary system
@@ -73,6 +104,36 @@ int restrict_link_by_builtin_and_secondary_trusted(
 }
 
 /**
+ * restrict_link_by_digsig_builtin_and_secondary - Restrict by digitalSignature.
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restrict_key: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in either the built-in or the secondary system
+ * keyrings. The new key must have the digitalSignature usage field set.
+ */
+int restrict_link_by_digsig_builtin_and_secondary(
+	struct key *dest_keyring,
+	const struct key_type *type,
+	const union key_payload *payload,
+	struct key *restrict_key)
+{
+	/* If we have a secondary trusted keyring, then that contains a link
+	 * through to the builtin keyring and the search will follow that link.
+	 */
+	if (type == &key_type_keyring &&
+	    dest_keyring == secondary_trusted_keys &&
+	    payload == &builtin_trusted_keys->payload)
+		/* Allow the builtin keyring to be added to the secondary */
+		return 0;
+
+	return restrict_link_by_digsig(dest_keyring, type, payload,
+				       secondary_trusted_keys);
+}
+
+/*
  * Allocate a struct key_restriction for the "builtin and secondary trust"
  * keyring. Only for use in system_trusted_keyring_init().
  */
@@ -85,11 +146,50 @@ static __init struct key_restriction *get_builtin_and_secondary_restriction(void
 	if (!restriction)
 		panic("Can't allocate secondary trusted keyring restriction\n");
 
-	restriction->check = restrict_link_by_builtin_and_secondary_trusted;
+	if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING))
+		restriction->check = restrict_link_by_builtin_secondary_and_machine;
+	else
+		restriction->check = restrict_link_by_builtin_and_secondary_trusted;
 
 	return restriction;
 }
 #endif
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+void __init set_machine_trusted_keys(struct key *keyring)
+{
+	machine_trusted_keys = keyring;
+
+	if (key_link(secondary_trusted_keys, machine_trusted_keys) < 0)
+		panic("Can't link (machine) trusted keyrings\n");
+}
+
+/**
+ * restrict_link_by_builtin_secondary_and_machine - Restrict keyring addition.
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restrict_key: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in either the built-in, the secondary, or
+ * the machine keyrings.
+ */
+int restrict_link_by_builtin_secondary_and_machine(
+	struct key *dest_keyring,
+	const struct key_type *type,
+	const union key_payload *payload,
+	struct key *restrict_key)
+{
+	if (machine_trusted_keys && type == &key_type_keyring &&
+	    dest_keyring == secondary_trusted_keys &&
+	    payload == &machine_trusted_keys->payload)
+		/* Allow the machine keyring to be added to the secondary */
+		return 0;
+
+	return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type,
+							      payload, restrict_key);
+}
+#endif
 
 /*
  * Create the trusted keyrings

crypto/asymmetric_keys/restrict.c

@@ -108,6 +108,90 @@ int restrict_link_by_signature(struct key *dest_keyring,
 	return ret;
 }
 
+/**
+ * restrict_link_by_ca - Restrict additions to a ring of CA keys
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @trust_keyring: Unused.
+ *
+ * Check if the new certificate is a CA. If it is a CA, then mark the new
+ * certificate as being ok to link.
+ *
+ * Returns 0 if the new certificate was accepted, -ENOKEY if the
+ * certificate is not a CA. -ENOPKG if the signature uses unsupported
+ * crypto, or some other error if there is a matching certificate but
+ * the signature check cannot be performed.
+ */
+int restrict_link_by_ca(struct key *dest_keyring,
+			const struct key_type *type,
+			const union key_payload *payload,
+			struct key *trust_keyring)
+{
+	const struct public_key *pkey;
+
+	if (type != &key_type_asymmetric)
+		return -EOPNOTSUPP;
+
+	pkey = payload->data[asym_crypto];
+	if (!pkey)
+		return -ENOPKG;
+	if (!test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
+		return -ENOKEY;
+	if (!test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
+		return -ENOKEY;
+	if (!IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX))
+		return 0;
+	if (test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
+		return -ENOKEY;
+
+	return 0;
+}
+
+/**
+ * restrict_link_by_digsig - Restrict additions to a ring of digsig keys
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @trust_keyring: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Check if the new certificate has digitalSignature usage set. If it is,
+ * then mark the new certificate as being ok to link. Afterwards verify
+ * the new certificate against the ones in the trust_keyring.
+ *
+ * Returns 0 if the new certificate was accepted, -ENOKEY if the
+ * certificate is not a digsig. -ENOPKG if the signature uses unsupported
+ * crypto, or some other error if there is a matching certificate but
+ * the signature check cannot be performed.
+ */
+int restrict_link_by_digsig(struct key *dest_keyring,
+			    const struct key_type *type,
+			    const union key_payload *payload,
+			    struct key *trust_keyring)
+{
+	const struct public_key *pkey;
+
+	if (type != &key_type_asymmetric)
+		return -EOPNOTSUPP;
+
+	pkey = payload->data[asym_crypto];
+
+	if (!pkey)
+		return -ENOPKG;
+
+	if (!test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
+		return -ENOKEY;
+
+	if (test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
+		return -ENOKEY;
+
+	if (test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
+		return -ENOKEY;
+
+	return restrict_link_by_signature(dest_keyring, type, payload,
+					  trust_keyring);
+}
+
 static bool match_either_id(const struct asymmetric_key_ids *pair,
 			    const struct asymmetric_key_id *single)
 {

crypto/asymmetric_keys/x509_cert_parser.c

@@ -564,6 +564,34 @@ int x509_process_extension(void *context, size_t hdrlen,
 		return 0;
 	}
 
+	if (ctx->last_oid == OID_keyUsage) {
+		/*
+		 * Get hold of the keyUsage bit string
+		 * v[1] is the encoding size
+		 *       (Expect either 0x02 or 0x03, making it 1 or 2 bytes)
+		 * v[2] is the number of unused bits in the bit string
+		 *       (If >= 3 keyCertSign is missing when v[1] = 0x02)
+		 * v[3] and possibly v[4] contain the bit string
+		 *
+		 * From RFC 5280 4.2.1.3:
+		 *   0x04 is where keyCertSign lands in this bit string
+		 *   0x80 is where digitalSignature lands in this bit string
+		 */
+		if (v[0] != ASN1_BTS)
+			return -EBADMSG;
+		if (vlen < 4)
+			return -EBADMSG;
+		if (v[2] >= 8)
+			return -EBADMSG;
+		if (v[3] & 0x80)
+			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_DIGITALSIG;
+		if (v[1] == 0x02 && v[2] <= 2 && (v[3] & 0x04))
+			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
+		else if (vlen > 4 && v[1] == 0x03 && (v[3] & 0x04))
+			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_KEYCERTSIGN;
+		return 0;
+	}
+
 	if (ctx->last_oid == OID_authorityKeyIdentifier) {
 		/* Get hold of the CA key fingerprint */
 		ctx->raw_akid = v;
@@ -571,6 +599,28 @@ int x509_process_extension(void *context, size_t hdrlen,
 		return 0;
 	}
 
+	if (ctx->last_oid == OID_basicConstraints) {
+		/*
+		 * Get hold of the basicConstraints
+		 * v[1] is the encoding size
+		 *	(Expect 0x2 or greater, making it 1 or more bytes)
+		 * v[2] is the encoding type
+		 *	(Expect an ASN1_BOOL for the CA)
+		 * v[3] is the contents of the ASN1_BOOL
+		 *      (Expect 1 if the CA is TRUE)
+		 * vlen should match the entire extension size
+		 */
+		if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
+			return -EBADMSG;
+		if (vlen < 2)
+			return -EBADMSG;
+		if (v[1] != vlen - 2)
+			return -EBADMSG;
+		if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
+			ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA;
+		return 0;
+	}
+
 	return 0;
 }
 

crypto/testmgr.c

@@ -4923,12 +4923,14 @@ static const struct alg_test_desc alg_test_descs[] = {
 	}, {
 		.alg = "ecdsa-nist-p256",
 		.test = alg_test_akcipher,
+		.fips_allowed = 1,
 		.suite = {
 			.akcipher = __VECS(ecdsa_nist_p256_tv_template)
 		}
 	}, {
 		.alg = "ecdsa-nist-p384",
 		.test = alg_test_akcipher,
+		.fips_allowed = 1,
 		.suite = {
 			.akcipher = __VECS(ecdsa_nist_p384_tv_template)
 		}

include/crypto/public_key.h

@@ -28,6 +28,10 @@ struct public_key {
 	bool key_is_private;
 	const char *id_type;
 	const char *pkey_algo;
+	unsigned long key_eflags;	/* key extension flags */
+#define KEY_EFLAG_CA		0	/* set if the CA basic constraints is set */
+#define KEY_EFLAG_DIGITALSIG	1	/* set if the digitalSignature usage is set */
+#define KEY_EFLAG_KEYCERTSIGN	2	/* set if the keyCertSign usage is set */
 };
 
 extern void public_key_free(struct public_key *key);
@@ -71,6 +75,32 @@ extern int restrict_link_by_key_or_keyring_chain(struct key *trust_keyring,
 						 const union key_payload *payload,
 						 struct key *trusted);
 
+#if IS_REACHABLE(CONFIG_ASYMMETRIC_KEY_TYPE)
+extern int restrict_link_by_ca(struct key *dest_keyring,
+			       const struct key_type *type,
+			       const union key_payload *payload,
+			       struct key *trust_keyring);
+int restrict_link_by_digsig(struct key *dest_keyring,
+			    const struct key_type *type,
+			    const union key_payload *payload,
+			    struct key *trust_keyring);
+#else
+static inline int restrict_link_by_ca(struct key *dest_keyring,
+				      const struct key_type *type,
+				      const union key_payload *payload,
+				      struct key *trust_keyring)
+{
+	return 0;
+}
+static inline int restrict_link_by_digsig(struct key *dest_keyring,
+					  const struct key_type *type,
+					  const union key_payload *payload,
+					  struct key *trust_keyring)
+{
+	return 0;
+}
+#endif
+
 extern int query_asymmetric_key(const struct kernel_pkey_params *,
 				struct kernel_pkey_query *);
 
@@ -80,7 +110,16 @@ extern int create_signature(struct kernel_pkey_params *, const void *, void *);
 extern int verify_signature(const struct key *,
 			    const struct public_key_signature *);
 
+#if IS_REACHABLE(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE)
 int public_key_verify_signature(const struct public_key *pkey,
 				const struct public_key_signature *sig);
+#else
+static inline
+int public_key_verify_signature(const struct public_key *pkey,
+				const struct public_key_signature *sig)
+{
+	return -EINVAL;
+}
+#endif
 
 #endif /* _LINUX_PUBLIC_KEY_H */

include/keys/system_keyring.h

@@ -16,10 +16,15 @@ extern int restrict_link_by_builtin_trusted(struct key *keyring,
 					    const struct key_type *type,
 					    const union key_payload *payload,
 					    struct key *restriction_key);
+int restrict_link_by_digsig_builtin(struct key *dest_keyring,
+				    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
+#define restrict_link_by_digsig_builtin restrict_link_reject
 
 static inline __init int load_module_cert(struct key *keyring)
 {
@@ -34,8 +39,28 @@ extern int restrict_link_by_builtin_and_secondary_trusted(
 	const struct key_type *type,
 	const union key_payload *payload,
 	struct key *restriction_key);
+extern 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);
 #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
+#endif
+
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+extern int restrict_link_by_builtin_secondary_and_machine(
+	struct key *dest_keyring,
+	const struct key_type *type,
+	const union key_payload *payload,
+	struct key *restrict_key);
+extern void __init set_machine_trusted_keys(struct key *keyring);
+#else
+#define restrict_link_by_builtin_secondary_and_machine restrict_link_by_builtin_trusted
+static inline void __init set_machine_trusted_keys(struct key *keyring)
+{
+}
 #endif
 
 extern struct pkcs7_message *pkcs7;

redhat/configs/rhel/generic/CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING

@@ -0,0 +1 @@
+# CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG_SECONDARY_KEYRING is not set

redhat/configs/rhel/generic/CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY

@@ -0,0 +1 @@
+CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY=y

redhat/configs/rhel/generic/CONFIG_INTEGRITY_CA_MACHINE_KEYRING

@@ -0,0 +1 @@
+CONFIG_INTEGRITY_CA_MACHINE_KEYRING=y

redhat/configs/rhel/generic/CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX

@@ -0,0 +1 @@
+CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX=y

redhat/configs/rhel/generic/CONFIG_INTEGRITY_MACHINE_KEYRING

@@ -0,0 +1 @@
+CONFIG_INTEGRITY_MACHINE_KEYRING=y

redhat/configs/rhel/generic/CONFIG_SECONDARY_TRUSTED_KEYRING

@@ -1 +1 @@
-# CONFIG_SECONDARY_TRUSTED_KEYRING is not set
+CONFIG_SECONDARY_TRUSTED_KEYRING=y

security/integrity/Kconfig

@@ -62,6 +62,40 @@ config INTEGRITY_PLATFORM_KEYRING
          provided by the platform for verifying the kexec'ed kerned image
          and, possibly, the initramfs signature.
 
+config INTEGRITY_MACHINE_KEYRING
+	bool "Provide a keyring to which Machine Owner Keys may be added"
+	depends on SECONDARY_TRUSTED_KEYRING
+	depends on INTEGRITY_ASYMMETRIC_KEYS
+	depends on SYSTEM_BLACKLIST_KEYRING
+	depends on LOAD_UEFI_KEYS
+	help
+	 If set, provide a keyring to which Machine Owner Keys (MOK) may
+	 be added. This keyring shall contain just MOK keys.  Unlike keys
+	 in the platform keyring, keys contained in the .machine keyring will
+	 be trusted within the kernel.
+
+config INTEGRITY_CA_MACHINE_KEYRING
+	bool "Enforce Machine Keyring CA Restrictions"
+	depends on INTEGRITY_MACHINE_KEYRING
+	default n
+	help
+	  The .machine keyring can be configured to enforce CA restriction
+	  on any key added to it.  By default no restrictions are in place
+	  and all Machine Owner Keys (MOK) are added to the machine keyring.
+	  If enabled only CA keys are added to the machine keyring, all
+	  other MOK keys load into the platform keyring.
+
+config INTEGRITY_CA_MACHINE_KEYRING_MAX
+	bool "Only CA keys without DigitialSignature usage set"
+	depends on INTEGRITY_CA_MACHINE_KEYRING
+	default n
+	help
+	  When selected, only load CA keys are loaded into the machine
+	  keyring that contain the CA bit set along with the keyCertSign
+	  Usage field.  Keys containing the digitialSignature Usage field
+	  will not be loaded. The remaining MOK keys are loaded into the
+	  .platform keyring.
+
 config LOAD_UEFI_KEYS
        depends on INTEGRITY_PLATFORM_KEYRING
        depends on EFI

security/integrity/Makefile

@@ -10,6 +10,7 @@ integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o
 integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
 integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o
 integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o
+integrity-$(CONFIG_INTEGRITY_MACHINE_KEYRING) += platform_certs/machine_keyring.o
 integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
 				      platform_certs/load_uefi.o \
 				      platform_certs/keyring_handler.o

security/integrity/digsig.c

@@ -30,12 +30,13 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
 	".ima",
 #endif
 	".platform",
+	".machine",
 };
 
 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
-#define restrict_link_to_ima restrict_link_by_builtin_and_secondary_trusted
+#define restrict_link_to_ima restrict_link_by_digsig_builtin_and_secondary
 #else
-#define restrict_link_to_ima restrict_link_by_builtin_trusted
+#define restrict_link_to_ima restrict_link_by_digsig_builtin
 #endif
 
 static struct key *integrity_keyring_from_id(const unsigned int id)
@@ -111,6 +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 && trust_moklist())
+			set_machine_trusted_keys(keyring[id]);
 		if (id == INTEGRITY_KEYRING_IMA)
 			load_module_cert(keyring[id]);
 	}
@@ -126,7 +129,9 @@ int __init integrity_init_keyring(const unsigned int id)
 	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW
 		| KEY_USR_READ | KEY_USR_SEARCH;
 
-	if (id == INTEGRITY_KEYRING_PLATFORM) {
+	if (id == INTEGRITY_KEYRING_PLATFORM ||
+	    (id == INTEGRITY_KEYRING_MACHINE &&
+	    !IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING))) {
 		restriction = NULL;
 		goto out;
 	}
@@ -138,8 +143,18 @@ int __init integrity_init_keyring(const unsigned int id)
 	if (!restriction)
 		return -ENOMEM;
 
-	restriction->check = restrict_link_to_ima;
-	perm |= KEY_USR_WRITE;
+	if (id == INTEGRITY_KEYRING_MACHINE)
+		restriction->check = restrict_link_by_ca;
+	else
+		restriction->check = restrict_link_to_ima;
+
+	/*
+	 * MOK keys can only be added through a read-only runtime services
+	 * UEFI variable during boot. No additional keys shall be allowed to
+	 * load into the machine keyring following init from userspace.
+	 */
+	if (id != INTEGRITY_KEYRING_MACHINE)
+		perm |= KEY_USR_WRITE;
 
 out:
 	return __integrity_init_keyring(id, perm, restriction);

security/integrity/evm/Kconfig

@@ -64,7 +64,8 @@ config EVM_LOAD_X509
 
 	   This option enables X509 certificate loading from the kernel
 	   onto the '.evm' trusted keyring.  A public key can be used to
-	   verify EVM integrity starting from the 'init' process.
+	   verify EVM integrity starting from the 'init' process. The
+	   key must have digitalSignature usage set.
 
 config EVM_X509_PATH
 	string "EVM X509 certificate path"

security/integrity/ima/Kconfig

@@ -263,7 +263,7 @@ config IMA_TRUSTED_KEYRING
 	   This option is deprecated in favor of INTEGRITY_TRUSTED_KEYRING
 
 config IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
-	bool "Permit keys validly signed by a built-in or secondary CA cert (EXPERIMENTAL)"
+	bool "Permit keys validly signed by a built-in or secondary CA cert"
 	depends on SYSTEM_TRUSTED_KEYRING
 	depends on SECONDARY_TRUSTED_KEYRING
 	depends on INTEGRITY_ASYMMETRIC_KEYS
@@ -272,7 +272,8 @@ config IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
 	help
 	  Keys may be added to the IMA or IMA blacklist keyrings, if the
 	  key is validly signed by a CA cert in the system built-in or
-	  secondary trusted keyrings.
+	  secondary trusted keyrings. The key must also have the
+	  digitalSignature usage set.
 
 	  Intermediate keys between those the kernel has compiled in and the
 	  IMA keys to be added may be added to the system secondary keyring,

security/integrity/integrity.h

@@ -151,7 +151,8 @@ int integrity_kernel_read(struct file *file, loff_t offset,
 #define INTEGRITY_KEYRING_EVM		0
 #define INTEGRITY_KEYRING_IMA		1
 #define INTEGRITY_KEYRING_PLATFORM	2
-#define INTEGRITY_KEYRING_MAX		3
+#define INTEGRITY_KEYRING_MACHINE	3
+#define INTEGRITY_KEYRING_MAX		4
 
 extern struct dentry *integrity_dir;
 
@@ -283,3 +284,17 @@ static inline void __init add_to_platform_keyring(const char *source,
 {
 }
 #endif
+
+#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
+void __init add_to_machine_keyring(const char *source, const void *data, size_t len);
+bool __init trust_moklist(void);
+#else
+static inline void __init add_to_machine_keyring(const char *source,
+						  const void *data, size_t len)
+{
+}
+static inline bool __init trust_moklist(void)
+{
+	return false;
+}
+#endif

security/integrity/platform_certs/keyring_handler.c

@@ -9,6 +9,7 @@
 #include <keys/asymmetric-type.h>
 #include <keys/system_keyring.h>
 #include "../integrity.h"
+#include "keyring_handler.h"
 
 static efi_guid_t efi_cert_x509_guid __initdata = EFI_CERT_X509_GUID;
 static efi_guid_t efi_cert_x509_sha256_guid __initdata =
@@ -66,7 +67,7 @@ static __init void uefi_revocation_list_x509(const char *source,
 
 /*
  * Return the appropriate handler for particular signature list types found in
- * the UEFI db and MokListRT tables.
+ * the UEFI db tables.
  */
 __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
 {
@@ -75,6 +76,21 @@ __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
 	return 0;
 }
 
+/*
+ * Return the appropriate handler for particular signature list types found in
+ * the MokListRT tables.
+ */
+__init efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type)
+{
+	if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0) {
+		if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING) && trust_moklist())
+			return add_to_machine_keyring;
+		else
+			return add_to_platform_keyring;
+	}
+	return 0;
+}
+
 /*
  * Return the appropriate handler for particular signature list types found in
  * the UEFI dbx and MokListXRT tables.

security/integrity/platform_certs/keyring_handler.h

@@ -24,6 +24,11 @@ void blacklist_binary(const char *source, const void *data, size_t len);
  */
 efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type);
 
+/*
+ * Return the handler for particular signature list types found in the mok.
+ */
+efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type);
+
 /*
  * Return the handler for particular signature list types found in the dbx.
  */

security/integrity/platform_certs/load_uefi.c

@@ -96,7 +96,7 @@ static int __init load_moklist_certs(void)
 		rc = parse_efi_signature_list("UEFI:MokListRT (MOKvar table)",
 					      mokvar_entry->data,
 					      mokvar_entry->data_size,
-					      get_handler_for_db);
+					      get_handler_for_mok);
 		/* All done if that worked. */
 		if (!rc)
 			return rc;
@@ -111,7 +111,7 @@ static int __init load_moklist_certs(void)
 	mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status);
 	if (mok) {
 		rc = parse_efi_signature_list("UEFI:MokListRT",
-					      mok, moksize, get_handler_for_db);
+					      mok, moksize, get_handler_for_mok);
 		kfree(mok);
 		if (rc)
 			pr_err("Couldn't parse MokListRT signatures: %d\n", rc);

security/integrity/platform_certs/machine_keyring.c

@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Machine keyring routines.
+ *
+ * Copyright (c) 2021, Oracle and/or its affiliates.
+ */
+
+#include <linux/efi.h>
+#include "../integrity.h"
+
+static bool trust_mok;
+
+static __init int machine_keyring_init(void)
+{
+	int rc;
+
+	rc = integrity_init_keyring(INTEGRITY_KEYRING_MACHINE);
+	if (rc)
+		return rc;
+
+	pr_notice("Machine keyring initialized\n");
+	return 0;
+}
+device_initcall(machine_keyring_init);
+
+void __init add_to_machine_keyring(const char *source, const void *data, size_t len)
+{
+	key_perm_t perm;
+	int rc;
+
+	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW;
+	rc = integrity_load_cert(INTEGRITY_KEYRING_MACHINE, source, data, len, perm);
+
+	/*
+	 * Some MOKList keys may not pass the machine keyring restrictions.
+	 * If the restriction check does not pass and the platform keyring
+	 * is configured, try to add it into that keyring instead.
+	 */
+	if (rc && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING))
+		rc = integrity_load_cert(INTEGRITY_KEYRING_PLATFORM, source,
+					 data, len, perm);
+
+	if (rc)
+		pr_info("Error adding keys to machine keyring %s\n", source);
+}
+
+/*
+ * Try to load the MokListTrustedRT MOK variable to see if we should trust
+ * the MOK keys within the kernel. It is not an error if this variable
+ * does not exist.  If it does not exist, MOK keys should not be trusted
+ * within the machine keyring.
+ */
+static __init bool uefi_check_trust_mok_keys(void)
+{
+	struct efi_mokvar_table_entry *mokvar_entry;
+
+	mokvar_entry = efi_mokvar_entry_find("MokListTrustedRT");
+
+	if (mokvar_entry)
+		return true;
+
+	return false;
+}
+
+bool __init trust_moklist(void)
+{
+	static bool initialized;
+
+	if (!initialized) {
+		initialized = true;
+
+		if (uefi_check_trust_mok_keys())
+			trust_mok = true;
+	}
+
+	return trust_mok;
+}