@@ -62,6 +62,18 @@ 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 CA 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 CA Machine Owner Keys (MOK) may
+ be added. This keyring shall contain just CA 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
@@ -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
@@ -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
@@ -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 +284,12 @@ 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);
+#else
+static inline void __init add_to_machine_keyring(const char *source,
+ const void *data, size_t len)
+{
+}
+#endif
new file mode 100644
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Machine keyring routines.
+ *
+ * Copyright (c) 2021, Oracle and/or its affiliates.
+ */
+
+#include "../integrity.h"
+
+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);
+}
Many UEFI Linux distributions boot using shim. The UEFI shim provides what is called Machine Owner Keys (MOK). Shim uses both the UEFI Secure Boot DB and MOK keys to validate the next step in the boot chain. The MOK facility can be used to import user generated keys. These keys can be used to sign an end-users development kernel build. When Linux boots, both UEFI Secure Boot DB and MOK keys get loaded in the Linux .platform keyring. Define a new Linux keyring called machine. This keyring shall contain just MOK CA keys and not the remaining keys in the platform keyring. This new machine keyring will be used in follow on patches. Unlike keys in the platform keyring, keys contained in the machine keyring will be trusted within the kernel if the end-user has chosen to do so. Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com> --- v1: Initial version v2: Removed destory keyring code v3: Unmodified from v2 v4: Add Kconfig, merged in "integrity: add add_to_mok_keyring" v5: Rename to machine keyring v6: Depend on EFI in kconfig (suggested by Mimi) Test to see if ".platform" keyring is configured in add_to_machine_keyring (suggested by Mimi) v7: Depend on LOAD_UEFI_KEYS instead EFI for mokvar code --- security/integrity/Kconfig | 12 ++++++ security/integrity/Makefile | 1 + security/integrity/digsig.c | 1 + security/integrity/integrity.h | 12 +++++- .../platform_certs/machine_keyring.c | 42 +++++++++++++++++++ 5 files changed, 67 insertions(+), 1 deletion(-) create mode 100644 security/integrity/platform_certs/machine_keyring.c