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From 7e8b52249deb775a2c32a115d9f295d1eaf2d7e1 Mon Sep 17 00:00:00 2001
From: Dave Howells <dhowells@redhat.com>
Date: Tue, 23 Oct 2012 09:36:28 -0400
Subject: [PATCH] Add an EFI signature blob parser and key loader.
X.509 certificates are loaded into the specified keyring as asymmetric type
keys.
Signed-off-by: David Howells <dhowells@redhat.com>
---
crypto/asymmetric_keys/Kconfig | 8 +++
crypto/asymmetric_keys/Makefile | 1 +
crypto/asymmetric_keys/efi_parser.c | 109 ++++++++++++++++++++++++++++++++++++
include/linux/efi.h | 4 ++
4 files changed, 122 insertions(+)
create mode 100644 crypto/asymmetric_keys/efi_parser.c
diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 4870f28403f5..4a1b50d73b80 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -67,4 +67,12 @@ config SIGNED_PE_FILE_VERIFICATION
This option provides support for verifying the signature(s) on a
signed PE binary.
+config EFI_SIGNATURE_LIST_PARSER
+ bool "EFI signature list parser"
+ depends on EFI
+ select X509_CERTIFICATE_PARSER
+ help
+ This option provides support for parsing EFI signature lists for
+ X.509 certificates and turning them into keys.
+
endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index e47fcd9ac5e8..6512f6596785 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -8,6 +8,7 @@ asymmetric_keys-y := asymmetric_type.o signature.o
obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o
+obj-$(CONFIG_EFI_SIGNATURE_LIST_PARSER) += efi_parser.o
#
# X.509 Certificate handling
diff --git a/crypto/asymmetric_keys/efi_parser.c b/crypto/asymmetric_keys/efi_parser.c
new file mode 100644
index 000000000000..424896a0b169
--- /dev/null
+++ b/crypto/asymmetric_keys/efi_parser.c
@@ -0,0 +1,109 @@
+/* EFI signature/key/certificate list parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "EFI: "fmt
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/err.h>
+#include <linux/efi.h>
+#include <keys/asymmetric-type.h>
+
+static __initdata efi_guid_t efi_cert_x509_guid = EFI_CERT_X509_GUID;
+
+/**
+ * parse_efi_signature_list - Parse an EFI signature list for certificates
+ * @data: The data blob to parse
+ * @size: The size of the data blob
+ * @keyring: The keyring to add extracted keys to
+ */
+int __init parse_efi_signature_list(const void *data, size_t size, struct key *keyring)
+{
+ unsigned offs = 0;
+ size_t lsize, esize, hsize, elsize;
+
+ pr_devel("-->%s(,%zu)\n", __func__, size);
+
+ while (size > 0) {
+ efi_signature_list_t list;
+ const efi_signature_data_t *elem;
+ key_ref_t key;
+
+ if (size < sizeof(list))
+ return -EBADMSG;
+
+ memcpy(&list, data, sizeof(list));
+ pr_devel("LIST[%04x] guid=%pUl ls=%x hs=%x ss=%x\n",
+ offs,
+ list.signature_type.b, list.signature_list_size,
+ list.signature_header_size, list.signature_size);
+
+ lsize = list.signature_list_size;
+ hsize = list.signature_header_size;
+ esize = list.signature_size;
+ elsize = lsize - sizeof(list) - hsize;
+
+ if (lsize > size) {
+ pr_devel("<--%s() = -EBADMSG [overrun @%x]\n",
+ __func__, offs);
+ return -EBADMSG;
+ }
+ if (lsize < sizeof(list) ||
+ lsize - sizeof(list) < hsize ||
+ esize < sizeof(*elem) ||
+ elsize < esize ||
+ elsize % esize != 0) {
+ pr_devel("- bad size combo @%x\n", offs);
+ return -EBADMSG;
+ }
+
+ if (efi_guidcmp(list.signature_type, efi_cert_x509_guid) != 0) {
+ data += lsize;
+ size -= lsize;
+ offs += lsize;
+ continue;
+ }
+
+ data += sizeof(list) + hsize;
+ size -= sizeof(list) + hsize;
+ offs += sizeof(list) + hsize;
+
+ for (; elsize > 0; elsize -= esize) {
+ elem = data;
+
+ pr_devel("ELEM[%04x]\n", offs);
+
+ key = key_create_or_update(
+ make_key_ref(keyring, 1),
+ "asymmetric",
+ NULL,
+ &elem->signature_data,
+ esize - sizeof(*elem),
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW,
+ KEY_ALLOC_NOT_IN_QUOTA |
+ KEY_ALLOC_TRUSTED);
+
+ if (IS_ERR(key))
+ pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
+ PTR_ERR(key));
+ else
+ pr_notice("Loaded cert '%s' linked to '%s'\n",
+ key_ref_to_ptr(key)->description,
+ keyring->description);
+
+ data += esize;
+ size -= esize;
+ offs += esize;
+ }
+ }
+
+ return 0;
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 5ce40e215f15..41359e548bcb 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -906,6 +906,10 @@ extern bool efi_poweroff_required(void);
(md) <= (efi_memory_desc_t *)((m)->map_end - (m)->desc_size); \
(md) = (void *)(md) + (m)->desc_size)
+struct key;
+extern int __init parse_efi_signature_list(const void *data, size_t size,
+ struct key *keyring);
+
/**
* efi_range_is_wc - check the WC bit on an address range
* @start: starting kvirt address
--
1.9.3
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