[PATCH 16/23] pefile: Parse a PE binary to find a key and a signature contained therein

[David Howells <dhowells@redhat.com>]

Parse a PE binary to find a key and a signature contained therein.  Later
patches will check the signature and add the key if the signature checks out.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 crypto/asymmetric_keys/Kconfig         |   10 ++
 crypto/asymmetric_keys/Makefile        |    8 +
 crypto/asymmetric_keys/pefile_parser.c |  178 ++++++++++++++++++++++++++++++++
 crypto/asymmetric_keys/pefile_parser.h |   31 ++++++
 4 files changed, 226 insertions(+), 1 deletion(-)
 create mode 100644 crypto/asymmetric_keys/pefile_parser.c
 create mode 100644 crypto/asymmetric_keys/pefile_parser.h


diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 413f3f6..2e7315c 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -31,7 +31,7 @@ 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.
 
@@ -44,4 +44,12 @@ config PKCS7_MESSAGE_PARSER
 	  This option provides support for parsing PKCS#7 format messages for
 	  signature data and provides the ability to verify the signature.
 
+config PE_FILE_PARSER
+	tristate "PE binary-wrapped key parser"
+	depends on X509_CERTIFICATE_PARSER
+	depends on PKCS7_MESSAGE_PARSER
+	help
+	  This option provides support for parsing signed PE binaries that
+	  contain an X.509 certificate in an internal section.
+
 endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index b6b39e7..61905d3 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -39,3 +39,11 @@ $(obj)/pkcs7_parser.o: $(obj)/pkcs7-asn1.h
 $(obj)/pkcs7-asn1.o: $(obj)/pkcs7-asn1.c $(obj)/pkcs7-asn1.h
 
 clean-files	+= pkcs7-asn1.c pkcs7-asn1.h
+
+#
+# Signed PE binary-wrapped key handling
+#
+obj-$(CONFIG_PE_FILE_PARSER) += pefile_key_parser.o
+
+pefile_key_parser-y := \
+	pefile_parser.o
diff --git a/crypto/asymmetric_keys/pefile_parser.c b/crypto/asymmetric_keys/pefile_parser.c
new file mode 100644
index 0000000..efae278
--- /dev/null
+++ b/crypto/asymmetric_keys/pefile_parser.c
@@ -0,0 +1,178 @@
+/* Parse a signed PE binary that wraps a key.
+ *
+ * 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) "PEFILE: "fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/pe.h>
+#include <keys/asymmetric-subtype.h>
+#include <keys/asymmetric-parser.h>
+#include <crypto/hash.h>
+#include "asymmetric_keys.h"
+#include "public_key.h"
+#include "pefile_parser.h"
+
+/*
+ * Parse a PE binary.
+ */
+static int pefile_parse_binary(struct key_preparsed_payload *prep,
+			       struct pefile_context *ctx)
+{
+	const struct mz_hdr *mz = prep->data;
+	const struct pe_hdr *pe;
+	const struct pe32_opt_hdr *pe32;
+	const struct pe32plus_opt_hdr *pe64;
+	const struct data_directory *ddir;
+	const struct data_dirent *dde;
+	const struct section_header *secs, *sec;
+	unsigned loop;
+	size_t cursor, datalen = prep->datalen;
+
+	kenter("");
+
+#define chkaddr(base, x, s)						\
+	do {								\
+		if ((x) < base || (s) >= datalen || (x) > datalen - (s))	\
+			return -ERANGE;					\
+	} while(0)
+
+	chkaddr(0, 0, sizeof(*mz));
+	if (mz->magic != MZ_MAGIC)
+		return -ELIBBAD;
+	cursor = sizeof(*mz);
+
+	chkaddr(cursor, mz->peaddr, sizeof(*pe));
+	pe = prep->data + mz->peaddr;
+	if (pe->magic != PE_MAGIC)
+		return -ELIBBAD;
+	cursor = mz->peaddr + sizeof(*pe);
+
+	chkaddr(0, cursor, sizeof(pe32->magic));
+	pe32 = prep->data + cursor;
+	pe64 = prep->data + cursor;
+	
+	switch (pe32->magic) {
+	case PE_OPT_MAGIC_PE32:
+		chkaddr(0, cursor, sizeof(*pe32));
+		ctx->image_checksum_offset =
+			(unsigned long)&pe32->csum - (unsigned long)prep->data;
+		ctx->header_size = pe32->header_size;
+		cursor += sizeof(*pe32);
+		ctx->n_data_dirents = pe32->data_dirs;
+		break;
+
+	case PE_OPT_MAGIC_PE32PLUS:
+		chkaddr(0, cursor, sizeof(*pe64));
+		ctx->image_checksum_offset =
+			(unsigned long)&pe64->csum - (unsigned long)prep->data;
+		ctx->header_size = pe64->header_size;
+		cursor += sizeof(*pe64);
+		ctx->n_data_dirents = pe64->data_dirs;
+		break;
+
+	default:
+		pr_devel("Unknown PEOPT magic = %04hx\n", pe32->magic);
+		return -ELIBBAD;
+	}
+
+	pr_devel("checksum @ %x\n", ctx->image_checksum_offset);
+	pr_devel("header size = %x\n", ctx->header_size);
+
+	chkaddr(0, cursor, sizeof(*ddir));
+	ddir = prep->data + cursor;
+	cursor += sizeof(*dde) * ctx->n_data_dirents;
+
+	ctx->cert_dirent_offset =
+		(unsigned long)&ddir->certs - (unsigned long)prep->data;
+	ctx->certs_size = ddir->certs.size;
+
+	if (!ddir->certs.virtual_address || !ddir->certs.size) {
+		pr_devel("Unsigned PE binary\n");
+		return -EKEYREJECTED;
+	}
+
+	chkaddr(cursor, ddir->certs.virtual_address, ddir->certs.size);
+	ctx->sig_offset = ddir->certs.virtual_address;
+	ctx->sig_len = ddir->certs.size;
+	pr_devel("cert = %x @%x [%*ph]\n",
+		 ctx->sig_len, ctx->sig_offset,
+		 ctx->sig_len, prep->data + ctx->sig_offset);
+
+	/* Parse the section table, checking the parameters and looking for the
+	 * section containing the list of keys.
+	 */
+	ctx->n_sections = pe->sections;
+	chkaddr(0, cursor, sizeof(*sec) * ctx->n_sections);
+	ctx->secs = secs = prep->data + cursor;
+	cursor += sizeof(*sec) * ctx->n_sections;
+
+	for (loop = 0; loop < ctx->n_sections; loop++) {
+		sec = &secs[loop];
+		chkaddr(cursor, sec->data_addr, sec->raw_data_size);
+		if (memcmp(sec->name, ".keylist", 8) == 0) {
+			ctx->keylist_offset = sec->data_addr;
+			ctx->keylist_len = sec->raw_data_size;
+		}
+	}
+
+	if (ctx->keylist_offset == 0) {
+		pr_devel("No .keylist section in PE binary\n");
+		return -ENOENT;
+	}
+
+	pr_devel("keylist = %x @%x [%*ph]\n",
+		 ctx->keylist_len, ctx->keylist_offset,
+		 ctx->keylist_len, prep->data + ctx->keylist_offset);
+
+	return 0;
+}
+
+/*
+ * Parse a PE binary.
+ */
+static int pefile_key_preparse(struct key_preparsed_payload *prep)
+{
+	struct pefile_context ctx;
+	int ret;
+
+	kenter("");
+
+	memset(&ctx, 0, sizeof(ctx));
+	ret = pefile_parse_binary(prep, &ctx);
+	if (ret < 0)
+		return ret;
+
+	return -ENOANO; // Not yet complete
+}
+
+static struct asymmetric_key_parser pefile_key_parser = {
+	.owner	= THIS_MODULE,
+	.name	= "pefile",
+	.parse	= pefile_key_preparse,
+};
+
+/*
+ * Module stuff
+ */
+static int __init pefile_key_init(void)
+{
+	return register_asymmetric_key_parser(&pefile_key_parser);
+}
+
+static void __exit pefile_key_exit(void)
+{
+	unregister_asymmetric_key_parser(&pefile_key_parser);
+}
+
+module_init(pefile_key_init);
+module_exit(pefile_key_exit);
diff --git a/crypto/asymmetric_keys/pefile_parser.h b/crypto/asymmetric_keys/pefile_parser.h
new file mode 100644
index 0000000..82bcaf6
--- /dev/null
+++ b/crypto/asymmetric_keys/pefile_parser.h
@@ -0,0 +1,31 @@
+/* PE Binary parser bits
+ *
+ * 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.
+ */
+#include "pkcs7_parser.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;
+	unsigned	keylist_offset;
+	unsigned	keylist_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 pkey_hash_algo digest_algo;	/* Digest algorithm */
+};