Merge tag 'keys-pefile-20140709' into keys-next

Here's a set of changes that implement a PE file signature checker.

This provides the following facility:

 (1) Extract the signature from the PE file.  This is a PKCS#7 message
     containing, as its data, a hash of the signed parts of the file.

 (2) Digest the signed parts of the file.

 (3) Compare the digest with the one from the PKCS#7 message.

 (4) Validate the signatures on the PKCS#7 message and indicate
     whether it was matched by a trusted key.
Signed-off-by: David Howells <dhowells@redhat.com>

crypto/asymmetric_keys/Kconfig

@@ -33,7 +33,7 @@ config X509_CERTIFICATE_PARSER
 	select ASN1
 	select OID_REGISTRY
 	help
-	  This option procides support for parsing X.509 format blobs for key
+	  This option provides support for parsing X.509 format blobs for key
 	  data and provides the ability to instantiate a crypto key from a
 	  public key packet found inside the certificate.
 
@@ -59,4 +59,13 @@ config PKCS7_TEST_KEY
 
 	  This is intended for testing the PKCS#7 parser.
 
+config SIGNED_PE_FILE_VERIFICATION
+	bool "Support for PE file signature verification"
+	depends on PKCS7_MESSAGE_PARSER=y
+	select ASN1
+	select OID_REGISTRY
+	help
+	  This option provides support for verifying the signature(s) on a
+	  signed PE binary.
+
 endif # ASYMMETRIC_KEY_TYPE

crypto/asymmetric_keys/Makefile

@@ -47,3 +47,18 @@ clean-files	+= pkcs7-asn1.c pkcs7-asn1.h
 obj-$(CONFIG_PKCS7_TEST_KEY) += pkcs7_test_key.o
 pkcs7_test_key-y := \
 	pkcs7_key_type.o
+
+#
+# Signed PE binary-wrapped key handling
+#
+obj-$(CONFIG_SIGNED_PE_FILE_VERIFICATION) += verify_signed_pefile.o
+
+verify_signed_pefile-y := \
+	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

crypto/asymmetric_keys/mscode.asn1

+--- Microsoft individual code signing data blob 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.
+---
+
+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
+}

crypto/asymmetric_keys/mscode_parser.c

+/* Parse a Microsoft Individual Code Signing blob
+ *
+ * Copyright (C) 2014 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) "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;
+	}
+
+	/*
+	 * pesign utility had a bug where it was putting
+	 * OID_msIndividualSPKeyPurpose instead of OID_msPeImageDataObjId
+	 * So allow both OIDs.
+	 */
+	if (oid != OID_msPeImageDataObjId &&
+	    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;
+}

crypto/asymmetric_keys/verify_pefile.h

+/* PE Binary parser bits
+ *
+ * Copyright (C) 2014 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.
+ */
+
+#include <linux/verify_pefile.h>
+#include <crypto/pkcs7.h>
+#include <crypto/hash_info.h>
+
+struct pefile_context {
+	unsigned	header_size;
+	unsigned	image_checksum_offset;
+	unsigned	cert_dirent_offset;
+	unsigned	n_data_dirents;
+	unsigned	n_sections;
+	unsigned	certs_size;
+	unsigned	sig_offset;
+	unsigned	sig_len;
+	const struct section_header *secs;
+	struct pkcs7_message *pkcs7;
+
+	/* PKCS#7 MS Individual Code Signing content */
+	const void	*digest;		/* Digest */
+	unsigned	digest_len;		/* Digest length */
+	enum hash_algo	digest_algo;		/* Digest algorithm */
+};
+
+#define kenter(FMT, ...)					\
+	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);

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 */
 

include/linux/verify_pefile.h

+/* Signed PE file verification
+ *
+ * Copyright (C) 2014 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.
+ */
+
+#ifndef _LINUX_VERIFY_PEFILE_H
+#define _LINUX_VERIFY_PEFILE_H
+
+extern int verify_pefile_signature(const void *pebuf, unsigned pelen,
+				   struct key *trusted_keyring, bool *_trusted);
+
+#endif /* _LINUX_VERIFY_PEFILE_H */