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lib/image/image4/image4_partial.c

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+/*
+ * Copyright (C) 2012 Apple Inc. All rights reserved.
+ *
+ * This document is the property of Apple Inc.
+ * It is considered confidential and proprietary.
+ *
+ * This document may not be reproduced or transmitted in any form,
+ * in whole or in part, without the express written permission of
+ * Apple Inc.
+ */
+
+#include <compiler.h>
+#include <debug.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libDER/libDER_config.h>
+#include <libDER/asn1Types.h>
+#include <libDER/DER_Decode.h>
+#include "image4_partial.h"
+
+// TODO - libDER/asn1Types.h is missing ASN1_EOC
+#ifndef ASN1_EOC
+#define ASN1_EOC	0x00
+#endif
+
+static int der_expect(const DERItem *bounds, DERTag tag, DERDecodedInfo *info,
+		      bool partial);
+static int der_restrict(DERItem *bounds, const DERItem *item);
+static int der_compare_ia5string(const DERItem *item, const char *s);
+static int der_skip_over(DERItem *bounds, const DERItem *item);
+static int der_expect_ia5string(DERItem *bounds, const char *s);
+
+#ifdef TEST
+static void hexdump(const void *buf, size_t len);
+#endif
+
+// Parse a partial buffer enough to identify and get type.
+int image4_get_partial(const void *buf, size_t buf_bytes,
+		       uint32_t *ret_type, uint32_t *ret_size)
+{
+	DERItem bounds;
+	DERDecodedInfo info;
+	// See sample Image4 header at the top of this file.
+	bounds.data = (DERByte *) buf;
+	bounds.length = buf_bytes;
+	dprintf(DEBUG_SPEW, "image4_get_partial %p,%u\n",
+		bounds.data, (unsigned) bounds.length);
+
+	// Outer SEQUENCE. Allow partial.
+	dprintf(DEBUG_SPEW, "Parse outer SEQUENCE\n");
+	if (der_expect(&bounds, ASN1_CONSTR_SEQUENCE, &info, true) != 0)
+		return -1;
+	// Infer Image4 size from the bounds of the sequence.
+	if (ret_size != NULL) {
+		DERSize offset = info.content.data - bounds.data;
+		if (offset + info.content.length < offset) {
+			dprintf(DEBUG_SPEW, "Sneaky size wraparound %llu\n",
+				(uint64_t) offset + info.content.length);
+			return -1;
+		}
+		*ret_size = offset + info.content.length;
+	}
+	// Update bounds to contents of SEQUENCE.
+	if (der_restrict(&bounds, &info.content) != 0)
+		return -1;
+
+	// IA5String "IMG4". Update bounds to skip over.
+	dprintf(DEBUG_SPEW, "Parse IA5String \"IMG4\"\n");
+	if (der_expect_ia5string(&bounds, "IMG4") != 0)
+		return -1;
+	
+	// Inner SEQUENCE. Allow partial.
+	dprintf(DEBUG_SPEW, "Parse inner sequence\n");
+	if (der_expect(&bounds, ASN1_CONSTR_SEQUENCE, &info, true) != 0)
+		return -1;
+	if (der_restrict(&bounds, &info.content) != 0)
+		return -1;
+
+	// IA5String "IM4P". Update bounds to skip over.
+	dprintf(DEBUG_SPEW, "Parse IA5String \"IM4P\"\n");
+	if (der_expect_ia5string(&bounds, "IM4P") != 0)
+		return -1;
+
+	// IA5String "type". We're interested in this one.
+	dprintf(DEBUG_SPEW, "Parse IA5String type\n");
+	if (der_expect(&bounds, ASN1_IA5_STRING, &info, false) != 0)
+		return -1;
+	if (info.content.length != sizeof(*ret_type)) {
+		dprintf(DEBUG_SPEW, "Expected %d byte tag, got %d\n",
+			(int) sizeof(*ret_type), (int) info.content.length);
+		return -1;
+	}
+	if (ret_type != NULL) {
+		uint32_t local_type;
+		memcpy(&local_type, info.content.data, sizeof(local_type));
+		*ret_type = swap32(local_type);
+	}
+	return 0;
+}
+
+static int
+der_expect(const DERItem *bounds, DERTag tag, DERDecodedInfo *info,
+	   bool partial)
+{
+	DERReturn ret;
+	dprintf(DEBUG_SPEW, "Bounds %p,%u\n",
+		bounds->data, (unsigned) bounds->length);
+	ret = DERDecodeItemPartialBuffer(bounds, info, partial);
+	if (ret != DR_Success) {
+		dprintf(DEBUG_SPEW, "Error decoding DER: %d\n", (int) ret);
+		return ret;
+	} else if (info->tag != tag) {
+		dprintf(DEBUG_SPEW,
+			"Didn't get expected tag 0x%llx, got 0x%llx\n",
+			(uint64_t) tag, (uint64_t) info->tag);
+		return -1;
+	} else {
+		// Got expected tag.
+		return 0;
+	}
+}
+
+static int
+der_restrict(DERItem *bounds, const DERItem *item)
+{
+	// Update *bounds to *item, keeping staying within *bounds.
+	RELEASE_ASSERT(item->data >= bounds->data);
+	DERByte *buf_start = bounds->data;
+	DERByte *buf_end = bounds->data + bounds->length;
+	// This should have been guaranteed elsewhere, but worth checking.
+	// Zero length returned *bounds allowed.
+	if ((item->data < buf_start) || (item->data > buf_end)) {
+		dprintf(DEBUG_SPEW, "DERItem.data=%p outside bounds %p,%p\n",
+			item->data, buf_start, buf_end);
+		return -1;
+	}
+	// Set *bounds to *item, then restrict range.
+	bounds->data = item->data;
+	bounds->length = __min((size_t)item->length, (size_t)(buf_end - bounds->data));
+	return 0;
+}
+
+static int
+der_compare_ia5string(const DERItem *item, const char *s)
+{
+	int cmp;
+	size_t len = strlen(s);
+	dprintf(DEBUG_SPEW, "content %p,%u\n", item->data, item->length);
+	if (item->length != len) {
+		dprintf(DEBUG_SPEW, "IA5String expected %s but length %d\n",
+			s, (int) len);
+		return -1;
+	}
+	cmp = memcmp(item->data, s, len);
+	if (cmp != 0) {
+		dprintf(DEBUG_SPEW, "Expected %s, got:\n", s);
+		dhexdump(DEBUG_SPEW, item->data, len);
+	}
+	return cmp;
+}
+
+static int
+der_skip_over(DERItem *bounds, const DERItem *item)
+{
+	DERSize skip, offset;
+	// Calculate number of bytes to move bounds->data to end of *item.
+	RELEASE_ASSERT(item->data >= bounds->data);
+	offset = item->data - bounds->data;
+	skip = offset + item->length;
+	if ((skip < offset) || (skip > bounds->length)) {
+		dprintf(DEBUG_SPEW, "Skipping over item -> outside bounds\n");
+		return -1;
+	}
+	bounds->data += skip;
+	bounds->length -= skip;
+	return 0;
+}
+
+static int
+der_expect_ia5string(DERItem *bounds, const char *s)
+{
+	// Get IA5String info, compare data, update bounds to skip over.
+	DERDecodedInfo info;
+	if (der_expect(bounds, ASN1_IA5_STRING, &info, false) != 0)
+		return -1;
+	if (der_compare_ia5string(&info.content, s) != 0)
+		return -1;
+	if (der_skip_over(bounds, &info.content) != 0)
+		return -1;
+	return 0;
+}
+
+
+#ifdef TEST
+// Run test with:
+// cc -Werror -Wall -O -o image4_partial image4_partial.c ../../pki/libDER/DER_Decode.c -DTEST -DDEBUG_LEVEL=30 -I../../../include -I../../pki && ./image4_partial
+// Try both -m32 and -m64
+#include <assert.h>
+
+int main() {
+	static const uint8_t big_img4[] = {		// 4GB-1 file
+		0x30, 0x84, 0xff, 0xff, 0xff, 0xf9,	// SEQUENCE { 4GB-7
+		0x16, 0x04, 0x49, 0x4d, 0x47, 0x34,	// IA5String 'IMG4'
+		0x30, 0x84, 0xff, 0xff, 0xff, 0xed,	// SEQUENCE { 4GB-19
+		0x16, 0x04, 0x49, 0x4d, 0x34, 0x50,	// IA5String 'IM4P'
+		0x16, 0x04, 0x41, 0x42, 0x43, 0x44,	// IA5String 'ABCD'
+	};
+	uint32_t type, size;
+	int ret = image4_get_partial(big_img4, sizeof(big_img4),
+				     &type, &size);
+	assert(ret == 0);
+	assert(memcmp(&type, "ABCD", 4) == 0);
+	assert(size == 0xffffffff);
+	printf("Pass\n");
+	return 0;
+}
+
+static void hexdump(const void *buf, size_t len) {
+	const uint8_t *p = buf;
+	size_t i;
+	for (i = 0; i < len; ++i)
+		printf("[%llu] = 0x%02x '%c'\n", (uint64_t) i, p[i], p[i]);
+}
+
+void _panic(const char *func, const char *str, ...) {
+	va_list args;
+	va_start(args, str);
+	printf("\n%s: ", func);
+	vprintf(str, args);
+	printf("\n\n");
+	va_end(args);
+	exit(1);
+}
+#endif // defined(TEST)

lib/image/image4/image4_partial.h

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+/*
+ * Copyright (C) 2012 Apple Inc. All rights reserved.
+ *
+ * This document is the property of Apple Inc.
+ * It is considered confidential and proprietary.
+ *
+ * This document may not be reproduced or transmitted in any form,
+ * in whole or in part, without the express written permission of
+ * Apple Inc.
+ */
+
+#ifndef IMAGE4_PARTIAL_H
+#define IMAGE4_PARTIAL_H	1
+
+#include <stdint.h>
+
+/*
+ * Maximum number of bytes needed to ID an Image4 file.
+ *
+ * Image4 header for a large (but <4GB) file contains:
+ *
+ * SEQUENCE {			30 84 xx xx xx xx
+ *   IA5String 'IMG4'           16 04 49 4d 47 34
+ *   SEQUENCE {                 30 84 yy yy yy yy
+ *     IA5String 'IM4P'         16 04 53 45 50 4f
+ *     IA5String 'abcd'         16 04 aa bb cc dd
+ */ 
+#define IMAGE4_ID_BYTES		30
+
+// Parse a partial buffer enough to identify and get type.
+// Return pointers can be NULL if not needed.
+int image4_get_partial(const void *buf, size_t buf_bytes,
+		       uint32_t *ret_type, uint32_t *ret_size);
+
+#endif // defined(IMAGE4_PARTIAL_H)

lib/image/image4/image4_wrapper.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (C) 2012-2013 Apple Inc. All rights reserved.
+ *
+ * This document is the property of Apple Inc.
+ * It is considered confidential and proprietary.
+ *
+ * This document may not be reproduced or transmitted in any form,
+ * in whole or in part, without the express written permission of
+ * Apple Inc.
+ */
+
+#ifndef IMAGE4_WRAPPER_H
+
+/*
+ * image4_process_superblock
+ *
+ * Searches the given bdev looking for image4 images.  Returns a count of found
+ * images.
+ */
+extern int
+image4_process_superblock(void *sblock, struct blockdev *bdev, off_t offset, uint32_t imageOptions);
+
+/*
+ * image4_free_bdev
+ *
+ * Frees resources for any previously found images on the specified bdev.
+ * Useful for starting afresh with a new image superblock.
+ */
+extern void
+image4_free_bdev(struct blockdev *bdev);
+
+/*
+ * image4_load
+ *
+ * Given an image_info handle and type from a previous image_find, load the image and 
+ * return the size and address of the payload (DATA tag).
+ */
+extern int
+image4_load(struct image_info *image, const u_int32_t *types, u_int32_t count, u_int32_t *actual, void **load_addr, size_t *load_len);
+
+/*
+ * image4_dump_list
+ *
+ * Print the list of images from the currently active bdev, if any.
+ */
+extern void
+image4_dump_list(bool detailed);
+
+
+/*
+ * image4_find
+ *
+ * Returns the image_info handle to the first image of the specified type
+ * from the currently active bdev, if any.
+ */
+extern struct image_info *
+image4_find(u_int32_t image_type);
+
+#endif // defined(IMAGE4_WRAPPER_H)

lib/image/image4/rules.mk

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+# Copyright (C) 2012, 2014 Apple Inc. All rights reserved.
+#
+# This document is the property of Apple Inc.
+# It is considered confidential and proprietary.
+#
+# This document may not be reproduced or transmitted in any form,
+# in whole or in part, without the express written permission of
+# Apple Inc.
+#
+LOCAL_DIR := $(GET_LOCAL_DIR)
+
+IMAGE_FORMAT := 4
+
+# Hack to link against SDKROOT or PLATFORMROOT until somebody figures
+# out why libImg4Decode is bouncing between locations.
+IMG4_IN_SDKROOT		:= $(realpath $(SDKROOT)/usr/local/lib/libImg4Decode_os.a)
+IMG4_IN_PLATFORMROOT	:= $(realpath $(PLATFORMROOT)/usr/local/lib/libImg4Decode_os.a)
+ifneq ($(IMG4_IN_SDKROOT),)
+EXTERNAL_STATICLIBS	+= $(IMG4_IN_SDKROOT)
+EXTERNAL_INCLUDES	+= $(SDKROOT)/usr/local/include/
+else
+ ifneq ($(IMG4_IN_PLATFORMROOT),)
+EXTERNAL_STATICLIBS	+= $(IMG4_IN_PLATFORMROOT)
+EXTERNAL_INCLUDES	+= $(PLATFORMROOT)/usr/local/include/
+ else
+$(error libImg4Decode.a not found in SDKROOT or PLATFORMROOT)
+ endif
+endif
+
+OPTIONS	+= WITH_IMAGE4=1
+
+MODULES += \
+	drivers/sha1 \
+	lib/cksum \
+	lib/image \
+	lib/pki
+
+ALL_OBJS += \
+	$(LOCAL_DIR)/image4_partial.o \
+	$(LOCAL_DIR)/image4_wrapper.o