[RFC,v2,01/12] integrity: Introduce a Linux keyring for the Machine Owner Key (MOK)

Commit Message

Eric Snowberg July 26, 2021, 5:13 p.m. UTC

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.

Add a new Linux keyring called .mok.  This keyring shall contain just
MOK keys and not the remaining keys in the platform keyring. This new
.mok keyring will be used in follow on patches.  Unlike keys in the
platform keyring, keys contained in the .mok keyring will be trusted
within the kernel if the end-user has chosen to do so.

Signed-off-by: Eric Snowberg <[e-mail]>
---
v1: Initial version
v2: Removed destory keyring code
---
 security/integrity/Makefile                   |  3 ++-
 security/integrity/digsig.c                   |  1 +
 security/integrity/integrity.h                |  3 ++-
 .../integrity/platform_certs/mok_keyring.c    | 21 +++++++++++++++++++
 4 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 security/integrity/platform_certs/mok_keyring.c

Patch

diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 7ee39d66cf16..8e2e98cba1f6 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -9,7 +9,8 @@  integrity-y := iint.o
 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-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o \
+						  platform_certs/mok_keyring.o
 integrity-$(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..e07334504ef1 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",
+	".mok",
 };
 
 #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index 547425c20e11..e0e17ccba2e6 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_MOK		3
+#define INTEGRITY_KEYRING_MAX		4
 
 extern struct dentry *integrity_dir;
 
diff --git a/security/integrity/platform_certs/mok_keyring.c b/security/integrity/platform_certs/mok_keyring.c
new file mode 100644
index 000000000000..b1ee45b77731
--- /dev/null
+++ b/security/integrity/platform_certs/mok_keyring.c
@@ -0,0 +1,21 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MOK keyring routines.
+ *
+ * Copyright (c) 2021, Oracle and/or its affiliates.
+ */
+
+#include "../integrity.h"
+
+static __init int mok_keyring_init(void)
+{
+	int rc;
+
+	rc = integrity_init_keyring(INTEGRITY_KEYRING_MOK);
+	if (rc)
+		return rc;
+
+	pr_notice("MOK Keyring initialized\n");
+	return 0;
+}
+device_initcall(mok_keyring_init);