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@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>

diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 413f3f6fb149a4279b029c0a1b9f13356481a286..2e7315c2790092678e70087a9331a8d547e5ea49 100644 (file)
--- 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 d63cb4320b9620fd77644ac144ed117923069a8d..2675146a41a951e15f90aaf199e5b3765eb8cb38 100644 (file)
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -40,3 +40,11 @@ $(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 (file)
index 0000000..fb80cf0
--- /dev/null
+++ b/crypto/asymmetric_keys/pefile_parser.c
@@ -0,0 +1,185 @@
+/* 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 -ELIBBAD;                                \
+       } 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);
+
+       if (cursor >= ctx->header_size || ctx->header_size >= datalen)
+               return -ELIBBAD;
+
+       if (ctx->n_data_dirents > (ctx->header_size - cursor) / sizeof(*dde) ||
+           ctx->n_data_dirents < sizeof(*ddir) / sizeof(*dde))
+               return -ELIBBAD;
+
+       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(ctx->header_size, 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;
+       if (ctx->n_sections > (ctx->header_size - cursor) / sizeof(*sec))
+               return -ELIBBAD;
+       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 (file)
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 */
+};