pefile: Parse the "Microsoft individual code signing" data blob

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

diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 2675146a41a951e15f90aaf199e5b3765eb8cb38..ddc64bb8c93310e3ec78da03c5945f78b1974bb5 100644 (file)
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -47,4 +47,11 @@ clean-files  += pkcs7-asn1.c pkcs7-asn1.h
 obj-$(CONFIG_PE_FILE_PARSER) += pefile_key_parser.o
 
 pefile_key_parser-y := \
-       pefile_parser.o
+       pefile_parser.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 (file)
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@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
+}

diff --git a/crypto/asymmetric_keys/mscode_parser.c b/crypto/asymmetric_keys/mscode_parser.c
new file mode 100644 (file)
index 0000000..0bd68e0
--- /dev/null
+++ b/crypto/asymmetric_keys/mscode_parser.c
@@ -0,0 +1,110 @@
+/* Parse a Microsoft Individual Code Signing blob
+ *
+ * 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) "MSCODE: "fmt
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/oid_registry.h>
+#include "pefile_parser.h"
+#include "mscode-asn1.h"
+
+/*
+ * Parse a Microsoft Individual Code Signing blob
+ */
+int mscode_parse(struct pefile_context *ctx)
+{
+       pr_devel("Data: %zu [%*ph]\n",
+                ctx->pkcs7->data_len + ctx->pkcs7->data_hdrlen,
+                (unsigned)(ctx->pkcs7->data_len + ctx->pkcs7->data_hdrlen),
+                ctx->pkcs7->data - ctx->pkcs7->data_hdrlen);
+
+       return asn1_ber_decoder(&mscode_decoder, ctx,
+                               ctx->pkcs7->data - ctx->pkcs7->data_hdrlen,
+                               ctx->pkcs7->data_len + ctx->pkcs7->data_hdrlen);
+}
+
+/*
+ * 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));
+               printk("MSCODE: Unknown OID: %s\n", buffer);
+               return -EBADMSG;
+       }
+
+       if (oid != OID_msIndividualSPKeyPurpose) {
+               printk("MSCODE: 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 = PKEY_HASH_MD4;
+               break;
+       case OID_md5:
+               ctx->digest_algo = PKEY_HASH_MD5;
+               break;
+       case OID_sha1:
+               ctx->digest_algo = PKEY_HASH_SHA1;
+               break;
+       case OID_sha256:
+               ctx->digest_algo = PKEY_HASH_SHA256;
+               break;
+
+       case OID__NR:
+               sprint_oid(value, vlen, buffer, sizeof(buffer));
+               printk("MSCODE: Unknown OID: %s\n", buffer);
+               return -EBADMSG;
+
+       default:
+               printk("MSCODE: 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/pefile_parser.c b/crypto/asymmetric_keys/pefile_parser.c
index 056500f4dd60e017ac13f91e3bbaefdd31e2c615..f1c8cc1b995d906e3a8c14dd0c4eb683fdc8b784 100644 (file)
--- a/crypto/asymmetric_keys/pefile_parser.c
+++ b/crypto/asymmetric_keys/pefile_parser.c
@@ -231,6 +231,12 @@ static int pefile_key_preparse(struct key_preparsed_payload *prep)
                goto error;
        }
 
+       ret = mscode_parse(&ctx);
+       if (ret < 0)
+               goto error;
+
+       pr_devel("Digest: %u [%*ph]\n", ctx.digest_len, ctx.digest_len, ctx.digest);
+
        ret = -ENOANO; // Not yet complete
 
 error:

diff --git a/crypto/asymmetric_keys/pefile_parser.h b/crypto/asymmetric_keys/pefile_parser.h
index 82bcaf6cd232dc03a20f8f8597576fb1591be1e7..c3462b79c1585d2ea942855b26f74938ff4304b3 100644 (file)
--- a/crypto/asymmetric_keys/pefile_parser.h
+++ b/crypto/asymmetric_keys/pefile_parser.h
@@ -29,3 +29,8 @@ struct pefile_context {
        unsigned        digest_len;             /* Digest length */
        enum pkey_hash_algo digest_algo;        /* Digest algorithm */
 };
+
+/*
+ * 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 edeff85cb1e81a6c74ad396c9008927c1604bb02..332dcf5fea586495caef078096bf6c31bbf02187 100644 (file)
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -52,8 +52,12 @@ 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_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 */