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Date: Tue, 30 Oct 2012 19:21:48 +0000
From: David Howells <dhowells@...hat.com>
To: rusty@...tcorp.com.au
Cc: dhowells@...hat.com, pjones@...hat.com, jwboyer@...hat.com,
mjg@...hat.com, dmitry.kasatkin@...el.com,
zohar@...ux.vnet.ibm.com, keescook@...omium.org,
keyrings@...ux-nfs.org, linux-kernel@...r.kernel.org
Subject: [PATCH 16/23] pefile: Parse a PE binary to find a key and a signature
contained therein
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@...hat.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@...hat.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@...hat.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 */
+};
--
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