Merge tag 'tpmdd-next-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd

Pull tpm updates from Jarkko Sakkinen:
 "In order to split the work a bit we've aligned with David Howells more
  or less that I take more hardware/firmware aligned keyring patches,
  and he takes care more of the framework aligned patches.

  For TPM the patches worth of highlighting are the fixes for
  refcounting provided by Lino Sanfilippo and James Bottomley.

  Eric B. has done a bunch obvious (but important) fixes but there's one
  a bit controversial: removal of asym_tpm. It was added in 2018 when
  TPM1 was already declared as insecure and world had moved on to TPM2.
  I don't know how this has passed all the filters but I did not have a
  chance to see the patches when they were out. I simply cannot commit
  to maintaining this because it was from all angles just wrong to take
  it in the first place to the mainline kernel. Nobody should use this
  module really for anything.

  Finally, there is a new keyring '.machine' to hold MOK keys ('Machine
  Owner Keys'). In the mok side MokListTrustedRT UEFI variable can be
  set, from which kernel knows that MOK keys are kernel trusted keys and
  they are populated to the machine keyring. This keyring linked to the
  secondary trusted keyring, which means that can be used like any
  kernel trusted keys. This keyring of course can be used to hold other
  MOK'ish keys in other platforms in future"

* tag 'tpmdd-next-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd: (24 commits)
  tpm: use try_get_ops() in tpm-space.c
  KEYS: asymmetric: properly validate hash_algo and encoding
  KEYS: asymmetric: enforce that sig algo matches key algo
  KEYS: remove support for asym_tpm keys
  tpm: fix reference counting for struct tpm_chip
  integrity: Only use machine keyring when uefi_check_trust_mok_keys is true
  integrity: Trust MOK keys if MokListTrustedRT found
  efi/mokvar: move up init order
  KEYS: Introduce link restriction for machine keys
  KEYS: store reference to machine keyring
  integrity: add new keyring handler for mok keys
  integrity: Introduce a Linux keyring called machine
  integrity: Fix warning about missing prototypes
  KEYS: trusted: Avoid calling null function trusted_key_exit
  KEYS: trusted: Fix trusted key backends when building as module
  tpm: xen-tpmfront: Use struct_size() helper
  KEYS: x509: remove dead code that set ->unsupported_sig
  KEYS: x509: remove never-set ->unsupported_key flag
  KEYS: x509: remove unused fields
  KEYS: x509: clearly distinguish between key and signature algorithms
  ...

8 files changed, 144 insertions, 6 deletions

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index 71f0177e8716..599429f99f99 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -62,6 +62,19 @@ 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
+	depends on !IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
+	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 LOAD_UEFI_KEYS
        depends on INTEGRITY_PLATFORM_KEYRING
        depends on EFI
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 7ee39d66cf16..d0ffe37dc1d6 100644
--- a/security/integrity/Makefile
+++ b/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
diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index 3b06a01bd0fd..c8c8a4a4e7a0 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -30,6 +30,7 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
 	".ima",
 #endif
 	".platform",
+	".machine",
 };
 
 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
@@ -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 +129,8 @@ 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) {
 		restriction = NULL;
 		goto out;
 	}
@@ -139,7 +143,14 @@ int __init integrity_init_keyring(const unsigned int id)
 		return -ENOMEM;
 
 	restriction->check = restrict_link_to_ima;
-	perm |= KEY_USR_WRITE;
+
+	/*
+	 * 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);
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 547425c20e11..2e214c761158 100644
--- a/security/integrity/integrity.h
+++ b/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
diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c
index 5604bd57c990..1db4d3b4356d 100644
--- a/security/integrity/platform_certs/keyring_handler.c
+++ b/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)
 {
@@ -77,6 +78,21 @@ __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
 
 /*
  * 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.
  */
 __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type)
diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
index 2462bfa08fe3..284558f30411 100644
--- a/security/integrity/platform_certs/keyring_handler.h
+++ b/security/integrity/platform_certs/keyring_handler.h
@@ -25,6 +25,11 @@ 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.
  */
 efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type);
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 08b6d12f99b4..5f45c3c07dbd 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -95,7 +95,7 @@ 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;
@@ -110,7 +110,7 @@ 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);
diff --git a/security/integrity/platform_certs/machine_keyring.c b/security/integrity/platform_certs/machine_keyring.c
new file mode 100644
index 000000000000..7aaed7950b6e
--- /dev/null
+++ b/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;
+}