[PATCH v2 4/4] powerpc: load firmware trusted keys into kernel keyring

[Nayna Jain]

The keys used to verify the Host OS kernel are managed by OPAL as secure
variables. This patch loads the verification keys into the .platform
keyring and revocation keys into .blacklist keyring. This enables
verification and loading of the kernels signed by the boot time keys which
are trusted by firmware.

Signed-off-by: Nayna Jain <nayna at linux.ibm.com>
---
 security/integrity/Kconfig                    |  9 ++
 security/integrity/Makefile                   |  3 +
 .../integrity/platform_certs/load_powerpc.c   | 94 +++++++++++++++++++
 3 files changed, 106 insertions(+)
 create mode 100644 security/integrity/platform_certs/load_powerpc.c

diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index 0bae6adb63a9..2b4109c157e2 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -72,6 +72,15 @@ config LOAD_IPL_KEYS
        depends on S390
        def_bool y
 
+config LOAD_PPC_KEYS
+	bool "Enable loading of platform and revocation keys for POWER"
+	depends on INTEGRITY_PLATFORM_KEYRING
+	depends on PPC_SECURE_BOOT
+	def_bool y
+	help
+	  Enable loading of db keys to the .platform keyring and dbx keys to
+	  the .blacklist keyring for powerpc based platforms.
+
 config INTEGRITY_AUDIT
 	bool "Enables integrity auditing support "
 	depends on AUDIT
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 525bf1d6e0db..9eeb6b053de3 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -14,6 +14,9 @@ integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
 				      platform_certs/load_uefi.o \
 				      platform_certs/keyring_handler.o
 integrity-$(CONFIG_LOAD_IPL_KEYS) += platform_certs/load_ipl_s390.o
+integrity-$(CONFIG_LOAD_PPC_KEYS) += platform_certs/efi_parser.o \
+					 platform_certs/load_powerpc.o \
+					 platform_certs/keyring_handler.o
 $(obj)/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar
 
 subdir-$(CONFIG_IMA)			+= ima
diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
new file mode 100644
index 000000000000..f4d869171062
--- /dev/null
+++ b/security/integrity/platform_certs/load_powerpc.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <nayna at linux.ibm.com>
+ *
+ * load_powernv.c
+ *      - loads keys and certs stored and controlled
+ *      by the firmware.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <asm/secboot.h>
+#include <asm/secvar.h>
+#include "keyring_handler.h"
+
+static struct secvar_operations *secvarops;
+
+/*
+ * Get a certificate list blob from the named EFI variable.
+ */
+static __init void *get_cert_list(u8 *key, unsigned long keylen,
+				  unsigned long *size)
+{
+	int rc;
+	void *db;
+
+	rc = secvarops->get_variable(key, keylen, NULL, size);
+	if (rc) {
+		pr_err("Couldn't get size: %d\n", rc);
+		return NULL;
+	}
+
+	db = kmalloc(*size, GFP_KERNEL);
+	if (!db)
+		return NULL;
+
+	rc = secvarops->get_variable(key, keylen, db, size);
+	if (rc) {
+		kfree(db);
+		pr_err("Error reading db var: %d\n", rc);
+		return NULL;
+	}
+
+	return db;
+}
+
+/*
+ * Load the certs contained in the UEFI databases into the platform trusted
+ * keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist
+ * keyring.
+ */
+static int __init load_powerpc_certs(void)
+{
+	void *db = NULL, *dbx = NULL;
+	unsigned long dbsize = 0, dbxsize = 0;
+	int rc = 0;
+
+	secvarops = get_secvar_ops();
+	if (!secvarops)
+		return -ENOENT;
+
+	/* Get db, and dbx.  They might not exist, so it isn't
+	 * an error if we can't get them.
+	 */
+	db = get_cert_list("db", 3, &dbsize);
+	if (!db) {
+		pr_err("Couldn't get db list from OPAL\n");
+	} else {
+		rc = parse_efi_signature_list("OPAL:db",
+				db, dbsize, get_handler_for_db);
+		if (rc)
+			pr_err("Couldn't parse db signatures: %d\n",
+					rc);
+		kfree(db);
+	}
+
+	dbx = get_cert_list("dbx", 3,  &dbxsize);
+	if (!dbx) {
+		pr_info("Couldn't get dbx list from OPAL\n");
+	} else {
+		rc = parse_efi_signature_list("OPAL:dbx",
+				dbx, dbxsize,
+				get_handler_for_dbx);
+		if (rc)
+			pr_err("Couldn't parse dbx signatures: %d\n", rc);
+		kfree(dbx);
+	}
+
+	return rc;
+}
+late_initcall(load_powerpc_certs);
-- 
2.20.1