[PATCH14/17] pefile: Parse the "Microsoft individual code signing" data blob
From: David Howells
Date: Wed Jul 09 2014 - 11:18:41 EST
The PKCS#7 certificate should contain a "Microsoft individual code signing"
data blob as its signed content. This blob contains a digest of the signed
content of the PE binary and the OID of the digest algorithm used (typically
SHA256).
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Acked-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
crypto/asymmetric_keys/Makefile | 9 ++
crypto/asymmetric_keys/mscode.asn1 | 28 +++++++
crypto/asymmetric_keys/mscode_parser.c | 120 ++++++++++++++++++++++++++++++++
crypto/asymmetric_keys/verify_pefile.c | 7 ++
crypto/asymmetric_keys/verify_pefile.h | 5 +
include/linux/oid_registry.h | 7 ++
6 files changed, 174 insertions(+), 2 deletions(-)
create mode 100644 crypto/asymmetric_keys/mscode.asn1
create mode 100644 crypto/asymmetric_keys/mscode_parser.c
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 3e4de52..e47fcd9 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -54,4 +54,11 @@ pkcs7_test_key-y := \
obj-$(CONFIG_SIGNED_PE_FILE_VERIFICATION) += verify_signed_pefile.o
verify_signed_pefile-y := \
- verify_pefile.o
+ verify_pefile.o \
+ mscode_parser.o \
+ mscode-asn1.o
+
+$(obj)/mscode_parser.o: $(obj)/mscode-asn1.h $(obj)/mscode-asn1.h
+$(obj)/mscode-asn1.o: $(obj)/mscode-asn1.c $(obj)/mscode-asn1.h
+
+clean-files += mscode-asn1.c mscode-asn1.h
diff --git a/crypto/asymmetric_keys/mscode.asn1 b/crypto/asymmetric_keys/mscode.asn1
new file mode 100644
index 0000000..6d09ba4
--- /dev/null
+++ b/crypto/asymmetric_keys/mscode.asn1
@@ -0,0 +1,28 @@
+--- Microsoft individual code signing data blob parser
+---
+--- Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+--- Written by David Howells (dhowells@xxxxxxxxxx)
+---
+--- 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.
+---
+
+MSCode ::= SEQUENCE {
+ type SEQUENCE {
+ contentType ContentType,
+ parameters ANY
+ },
+ content SEQUENCE {
+ digestAlgorithm DigestAlgorithmIdentifier,
+ digest OCTET STRING ({ mscode_note_digest })
+ }
+}
+
+ContentType ::= OBJECT IDENTIFIER ({ mscode_note_content_type })
+
+DigestAlgorithmIdentifier ::= SEQUENCE {
+ algorithm OBJECT IDENTIFIER ({ mscode_note_digest_algo }),
+ parameters ANY OPTIONAL
+}
diff --git a/crypto/asymmetric_keys/mscode_parser.c b/crypto/asymmetric_keys/mscode_parser.c
new file mode 100644
index 0000000..09336c3
--- /dev/null
+++ b/crypto/asymmetric_keys/mscode_parser.c
@@ -0,0 +1,120 @@
+/* Parse a Microsoft Individual Code Signing blob
+ *
+ * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * 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) "MSCODE: "fmt
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/oid_registry.h>
+#include <crypto/pkcs7.h>
+#include "verify_pefile.h"
+#include "mscode-asn1.h"
+
+/*
+ * Parse a Microsoft Individual Code Signing blob
+ */
+int mscode_parse(struct pefile_context *ctx)
+{
+ const void *content_data;
+ size_t data_len;
+ int ret;
+
+ ret = pkcs7_get_content_data(ctx->pkcs7, &content_data, &data_len, 1);
+
+ if (ret) {
+ pr_debug("PKCS#7 message does not contain data\n");
+ return ret;
+ }
+
+ pr_devel("Data: %zu [%*ph]\n", data_len, (unsigned)(data_len),
+ content_data);
+
+ return asn1_ber_decoder(&mscode_decoder, ctx, content_data, data_len);
+}
+
+/*
+ * Check the content type OID
+ */
+int mscode_note_content_type(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ enum OID oid;
+
+ oid = look_up_OID(value, vlen);
+ if (oid == OID__NR) {
+ char buffer[50];
+
+ sprint_oid(value, vlen, buffer, sizeof(buffer));
+ pr_err("Unknown OID: %s\n", buffer);
+ return -EBADMSG;
+ }
+
+ if (oid != OID_msIndividualSPKeyPurpose) {
+ pr_err("Unexpected content type OID %u\n", oid);
+ return -EBADMSG;
+ }
+
+ return 0;
+}
+
+/*
+ * Note the digest algorithm OID
+ */
+int mscode_note_digest_algo(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct pefile_context *ctx = context;
+ char buffer[50];
+ enum OID oid;
+
+ oid = look_up_OID(value, vlen);
+ switch (oid) {
+ case OID_md4:
+ ctx->digest_algo = HASH_ALGO_MD4;
+ break;
+ case OID_md5:
+ ctx->digest_algo = HASH_ALGO_MD5;
+ break;
+ case OID_sha1:
+ ctx->digest_algo = HASH_ALGO_SHA1;
+ break;
+ case OID_sha256:
+ ctx->digest_algo = HASH_ALGO_SHA256;
+ break;
+
+ case OID__NR:
+ sprint_oid(value, vlen, buffer, sizeof(buffer));
+ pr_err("Unknown OID: %s\n", buffer);
+ return -EBADMSG;
+
+ default:
+ pr_err("Unsupported content type: %u\n", oid);
+ return -ENOPKG;
+ }
+
+ return 0;
+}
+
+/*
+ * Note the digest we're guaranteeing with this certificate
+ */
+int mscode_note_digest(void *context, size_t hdrlen,
+ unsigned char tag,
+ const void *value, size_t vlen)
+{
+ struct pefile_context *ctx = context;
+
+ ctx->digest = value;
+ ctx->digest_len = vlen;
+ return 0;
+}
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 13f3b44..b975918 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -245,6 +245,13 @@ int verify_pefile_signature(const void *pebuf, unsigned pelen,
goto error;
}
+ ret = mscode_parse(&ctx);
+ if (ret < 0)
+ goto error;
+
+ pr_debug("Digest: %u [%*ph]\n",
+ ctx.digest_len, ctx.digest_len, ctx.digest);
+
ret = -ENOANO; // Not yet complete
error:
diff --git a/crypto/asymmetric_keys/verify_pefile.h b/crypto/asymmetric_keys/verify_pefile.h
index e165d23..55d5f7e 100644
--- a/crypto/asymmetric_keys/verify_pefile.h
+++ b/crypto/asymmetric_keys/verify_pefile.h
@@ -35,3 +35,8 @@ struct pefile_context {
pr_devel("==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
pr_devel("<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
+
+/*
+ * mscode_parser.c
+ */
+extern int mscode_parse(struct pefile_context *ctx);
diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index edeff85..c2bbf67 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -52,8 +52,13 @@ enum OID {
OID_md4, /* 1.2.840.113549.2.4 */
OID_md5, /* 1.2.840.113549.2.5 */
- OID_certAuthInfoAccess, /* 1.3.6.1.5.5.7.1.1 */
+ /* Microsoft Authenticode & Software Publishing */
+ OID_msIndirectData, /* 1.3.6.1.4.1.311.2.1.4 */
+ OID_msPeImageDataObjId, /* 1.3.6.1.4.1.311.2.1.15 */
+ OID_msIndividualSPKeyPurpose, /* 1.3.6.1.4.1.311.2.1.21 */
OID_msOutlookExpress, /* 1.3.6.1.4.1.311.16.4 */
+
+ OID_certAuthInfoAccess, /* 1.3.6.1.5.5.7.1.1 */
OID_sha1, /* 1.3.14.3.2.26 */
OID_sha256, /* 2.16.840.1.101.3.4.2.1 */
--
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