From 36e79114d27589e9ccd494b04f79577703d8b0a5 Mon Sep 17 00:00:00 2001
From: Jeremy Kerr <jeremy.kerr@canonical.com>
Date: Thu, 2 Aug 2012 16:43:08 +0800
Subject: [PATCH] sbattach: fix --detach

sbattach --detach isn't working, as we're not properly setting sigbuf in
image_pecoff parse.

This change ensures we populate sigbuf when we find a valid cert table.
Also, add a test case for this.

Bug report & initial patch from from Steve Langasek.

Signed-off-by: Jeremy Kerr <jeremy.kerr@canonical.com>
---
 image.c                     | 24 ++++++++++++++++++++----
 tests/Makefile.am           |  1 +
 tests/sign-detach-verify.sh | 10 ++++++++++
 3 files changed, 31 insertions(+), 4 deletions(-)
 create mode 100755 tests/sign-detach-verify.sh

diff --git a/image.c b/image.c
index f8ee1d6..2508766 100644
--- a/image.c
+++ b/image.c
@@ -47,6 +47,9 @@
 
 #define DATA_DIR_CERT_TABLE	4
 
+#define CERT_TABLE_TYPE_PKCS	0x0002	/* PKCS signedData */
+#define CERT_TABLE_REVISION	0x0200	/* revision 2 */
+
 /**
  * The PE/COFF headers export struct fields as arrays of chars. So, define
  * a couple of accessor functions that allow fields to be deferenced as their
@@ -75,6 +78,7 @@ static uint16_t __pehdr_u16(char field[])
 
 static int image_pecoff_parse(struct image *image)
 {
+	struct cert_table_header *cert_table;
 	char nt_sig[] = {'P', 'E', 0, 0};
 	size_t size = image->size;
 	uint32_t addr;
@@ -142,9 +146,21 @@ static int image_pecoff_parse(struct image *image)
 
 	image->cert_table_size = image->data_dir_sigtable->size;
 	if (image->cert_table_size)
-		image->cert_table = image->buf + image->data_dir_sigtable->addr;
+		cert_table = image->buf + image->data_dir_sigtable->addr;
 	else
-		image->cert_table = NULL;
+		cert_table = NULL;
+
+	image->cert_table = cert_table;
+
+	/* if we have a valid cert table header, populate sigbuf as a shadow
+	 * copy of the cert table */
+	if (cert_table && cert_table->revision == CERT_TABLE_REVISION &&
+			cert_table->type == CERT_TABLE_TYPE_PKCS &&
+			cert_table->size < size) {
+		image->sigsize = cert_table->size;
+		image->sigbuf = talloc_memdup(image, cert_table + 1,
+				image->sigsize);
+	}
 
 	image->sections = pehdr_u16(image->pehdr->f_nscns);
 	image->scnhdr = (void *)(image->aouthdr+1);
@@ -387,8 +403,8 @@ int image_write(struct image *image, const char *filename)
 	if (is_signed) {
 		cert_table_header.size = image->sigsize +
 						sizeof(cert_table_header);
-		cert_table_header.revision = 0x0200; /* = revision 2 */
-		cert_table_header.type = 0x0002; /* PKCS signedData */
+		cert_table_header.revision = CERT_TABLE_REVISION;
+		cert_table_header.type = CERT_TABLE_TYPE_PKCS;
 
 		len = sizeof(cert_table_header) + image->sigsize;
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index a2e80cc..03af648 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -37,6 +37,7 @@ $(test_cert): $(test_key) Makefile
 
 TESTS = sign-verify.sh \
 	sign-verify-detached.sh \
+	sign-detach-verify.sh \
 	sign-attach-verify.sh \
 	sign-missing-image.sh \
 	sign-missing-cert.sh \
diff --git a/tests/sign-detach-verify.sh b/tests/sign-detach-verify.sh
new file mode 100755
index 0000000..4356816
--- /dev/null
+++ b/tests/sign-detach-verify.sh
@@ -0,0 +1,10 @@
+#!/bin/bash -e
+
+. "$srcdir/common.sh"
+
+signed="test.signed"
+sig="test.sig"
+
+"$sbsign" --cert "$cert" --key "$key" --output "$signed" "$image"
+"$sbattach" --detach "$sig" "$signed"
+"$sbverify" --cert "$cert" --detached $sig "$image"