drivers/staging/greybus/manifest.c - linux - Git at Google

 /*
  * Greybus module manifest parsing
  *
  * Copyright 2014 Google Inc.
  *
  * Released under the GPLv2 only.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/err.h>

 #include "greybus.h"

 /*
  * We scan the manifest once to identify where all the descriptors
  * are.  The result is a list of these manifest_desc structures.  We
  * then pick through them for what we're looking for (starting with
  * the module descriptor).  As each is processed we remove it from
  * the list.  When we're done the list should (probably) be empty.
  */
 struct manifest_desc {
 	struct list_head		links;

 	size_t				size;
 	void				*data;
 	enum greybus_descriptor_type	type;
 };

 static LIST_HEAD(manifest_descs);

 static void release_manifest_descriptor(struct manifest_desc *descriptor)
 {
 	list_del(&descriptor->links);
 	kfree(descriptor);
 }

 static void release_manifest_descriptors(void)
 {
 	struct manifest_desc *descriptor;
 	struct manifest_desc *next;

 	list_for_each_entry_safe(descriptor, next, &manifest_descs, links)
 		release_manifest_descriptor(descriptor);
 }

 /*
  * Validate the given descriptor.  Its reported size must fit within
  * the number of bytes reamining, and it must have a recognized
  * type.  Check that the reported size is at least as big as what
  * we expect to see.  (It could be bigger, perhaps for a new version
  * of the format.)
  *
  * Returns the number of bytes consumed by the descriptor, or a
  * negative errno.
  */
 static int identify_descriptor(struct greybus_descriptor *desc, size_t size)
 {
 	struct greybus_descriptor_header *desc_header = &desc->header;
 	struct manifest_desc *descriptor;
 	int desc_size;
 	size_t expected_size;

 	if (size < sizeof(*desc_header)) {
 		pr_err("manifest too small\n");
 		return -EINVAL;		/* Must at least have header */
 	}

 	desc_size = (int)le16_to_cpu(desc_header->size);
 	if ((size_t)desc_size > size) {
 		pr_err("descriptor too big\n");
 		return -EINVAL;
 	}

 	switch (desc_header->type) {
 	case GREYBUS_TYPE_MODULE:
 		if (desc_size < sizeof(struct greybus_descriptor_module)) {
 			pr_err("module descriptor too small (%u)\n",
 				desc_size);
 			return -EINVAL;
 		}
 		break;
 	case GREYBUS_TYPE_STRING:
 		expected_size = sizeof(struct greybus_descriptor_header);
 		expected_size += sizeof(struct greybus_descriptor_string);
 		expected_size += (size_t)desc->string.length;
 		if (desc_size < expected_size) {
 			pr_err("string descriptor too small (%u)\n",
 				desc_size);
 			return -EINVAL;
 		}
 		break;
 	case GREYBUS_TYPE_INTERFACE:
 		break;
 	case GREYBUS_TYPE_CPORT:
 		if (desc_size < sizeof(struct greybus_descriptor_cport)) {
 			pr_err("cport descriptor too small (%u)\n",
 				desc_size);
 			return -EINVAL;
 		}
 		break;
 	case GREYBUS_TYPE_CLASS:
 		pr_warn("class descriptor found (ignoring)\n");
 		break;
 	case GREYBUS_TYPE_INVALID:
 	default:
 		pr_err("invalid descriptor type (%hhu)\n", desc_header->type);
 		return -EINVAL;
 	}

 	descriptor = kzalloc(sizeof(*descriptor), GFP_KERNEL);
 	if (!descriptor)
 		return -ENOMEM;

 	descriptor->size = desc_size;
 	descriptor->data = (u8 *)desc + sizeof(*desc_header);
 	descriptor->type = desc_header->type;
 	list_add_tail(&descriptor->links, &manifest_descs);

 	return desc_size;
 }

 /*
  * Find the string descriptor having the given id, validate it, and
  * allocate a duplicate copy of it.  The duplicate has an extra byte
  * which guarantees the returned string is NUL-terminated.
  *
  * String index 0 is valid (it represents "no string"), and for
  * that a null pointer is returned.
  *
  * Otherwise returns a pointer to a newly-allocated copy of the
  * descriptor string, or an error-coded pointer on failure.
  */
 static char *gb_string_get(u8 string_id)
 {
 	struct greybus_descriptor_string *desc_string;
 	struct manifest_desc *descriptor;
 	bool found = false;
 	char *string;

 	/* A zero string id means no string (but no error) */
 	if (!string_id)
 		return NULL;

 	list_for_each_entry(descriptor, &manifest_descs, links) {

 		if (descriptor->type != GREYBUS_TYPE_STRING)
 			continue;

 		desc_string = descriptor->data;
 		if (desc_string->id == string_id) {
 			found = true;
 			break;
 		}
 	}
 	if (!found)
 		return ERR_PTR(-ENOENT);

 	/* Allocate an extra byte so we can guarantee it's NUL-terminated */
 	string = kmemdup(&desc_string->string, (size_t)desc_string->length + 1,
 				GFP_KERNEL);
 	if (!string)
 		return ERR_PTR(-ENOMEM);
 	string[desc_string->length] = '\0';

 	/* Ok we've used this string, so we're done with it */
 	release_manifest_descriptor(descriptor);

 	return string;
 }

 /*
  * Find cport descriptors in the manifest and set up data structures
  * for the functions that use them.  Returns the number of interfaces
  * set up for the given module, or 0 if there is an error.
  */
 static u32 gb_manifest_parse_cports(struct gb_interface *interface)
 {
 	u32 count = 0;

 	while (true) {
 		struct manifest_desc *descriptor;
 		struct greybus_descriptor_cport *desc_cport;
 		enum greybus_protocol protocol;
 		u16 cport_id;
 		bool found;

 		/* Find a cport descriptor */
 		found = false;
 		list_for_each_entry(descriptor, &manifest_descs, links) {
 			if (descriptor->type == GREYBUS_TYPE_CPORT) {
 				desc_cport = descriptor->data;
 				if (desc_cport->interface == interface->id) {
 					found = true;
 					break;
 				}
 			}
 		}
 		if (!found)
 			break;

 		/* Found one.  Set up its function structure */
 		protocol = (enum greybus_protocol)desc_cport->protocol;
 		cport_id = le16_to_cpu(desc_cport->id);
 		if (!gb_connection_create(interface, cport_id, protocol))
 			return 0;	/* Error */

 		count++;
 		/* Release the cport descriptor */
 		release_manifest_descriptor(descriptor);
 	}

 	return count;
 }

 /*
  * Find interface descriptors in the manifest and set up their data
  * structures.  Returns the number of interfaces set up for the
  * given module.
  */
 static u32 gb_manifest_parse_interfaces(struct gb_module *gmod)
 {
 	u32 count = 0;

 	while (true) {
 		struct manifest_desc *descriptor;
 		struct greybus_descriptor_interface *desc_interface;
 		struct gb_interface *interface;
 		bool found = false;

 		/* Find an interface descriptor */
 		list_for_each_entry(descriptor, &manifest_descs, links) {
 			if (descriptor->type == GREYBUS_TYPE_INTERFACE) {
 				found = true;
 				break;
 			}
 		}
 		if (!found)
 			break;

 		/* Found one.  Set up its interface structure*/
 		desc_interface = descriptor->data;
 		interface = gb_interface_create(gmod, desc_interface->id);
 		if (!interface)
 			return 0;	/* Error */

 		/* Now go set up this interface's functions and cports */
 		if (!gb_manifest_parse_cports(interface))
 			return 0;	/* Error parsing cports */

 		count++;

 		/* Done with this interface descriptor */
 		release_manifest_descriptor(descriptor);
 	}

 	return count;
 }

 static bool gb_manifest_parse_module(struct gb_module *gmod,
 					struct manifest_desc *module_desc)
 {
 	struct greybus_descriptor_module *desc_module = module_desc->data;

 	/* Handle the strings first--they can fail */
 	gmod->vendor_string = gb_string_get(desc_module->vendor_stringid);
 	if (IS_ERR(gmod->vendor_string))
 		return false;

 	gmod->product_string = gb_string_get(desc_module->product_stringid);
 	if (IS_ERR(gmod->product_string)) {
 		goto out_err;
 	}

 	gmod->vendor = le16_to_cpu(desc_module->vendor);
 	gmod->product = le16_to_cpu(desc_module->product);
 	gmod->version = le16_to_cpu(desc_module->version);
 	gmod->unique_id = le64_to_cpu(desc_module->unique_id);

 	/* Release the module descriptor, now that we're done with it */
 	release_manifest_descriptor(module_desc);

 	/* A module must have at least one interface descriptor */
 	if (!gb_manifest_parse_interfaces(gmod)) {
 		pr_err("manifest interface descriptors not valid\n");
 		goto out_err;
 	}

 	return true;
 out_err:
 	kfree(gmod->product_string);
 	gmod->product_string = NULL;
 	kfree(gmod->vendor_string);
 	gmod->vendor_string = NULL;

 	return false;
 }

 /*
  * Parse a buffer containing a module manifest.
  *
  * If we find anything wrong with the content/format of the buffer
  * we reject it.
  *
  * The first requirement is that the manifest's version is
  * one we can parse.
  *
  * We make an initial pass through the buffer and identify all of
  * the descriptors it contains, keeping track for each its type
  * and the location size of its data in the buffer.
  *
  * Next we scan the descriptors, looking for a module descriptor;
  * there must be exactly one of those.  When found, we record the
  * information it contains, and then remove that descriptor (and any
  * string descriptors it refers to) from further consideration.
  *
  * After that we look for the module's interfaces--there must be at
  * least one of those.
  *
  * Returns true if parsing was successful, false otherwise.
  */
 bool gb_manifest_parse(struct gb_module *gmod, void *data, size_t size)
 {
 	struct greybus_manifest *manifest;
 	struct greybus_manifest_header *header;
 	struct greybus_descriptor *desc;
 	struct manifest_desc *descriptor;
 	struct manifest_desc *module_desc = NULL;
 	u16 manifest_size;
 	u32 found = 0;
 	bool result = false;

 	/* we have to have at _least_ the manifest header */
 	if (size <= sizeof(manifest->header)) {
 		pr_err("short manifest (%zu)\n", size);
 		return false;
 	}

 	/* Make sure the size is right */
 	manifest = data;
 	header = &manifest->header;
 	manifest_size = le16_to_cpu(header->size);
 	if (manifest_size != size) {
 		pr_err("manifest size mismatch %zu != %hu\n",
 			size, manifest_size);
 		return false;
 	}

 	/* Validate major/minor number */
 	if (header->version_major > GREYBUS_VERSION_MAJOR) {
 		pr_err("manifest version too new (%hhu.%hhu > %hhu.%hhu)\n",
 			header->version_major, header->version_minor,
 			GREYBUS_VERSION_MAJOR, GREYBUS_VERSION_MINOR);
 		return false;
 	}

 	/* OK, find all the descriptors */
 	desc = (struct greybus_descriptor *)(header + 1);
 	size -= sizeof(*header);
 	while (size) {
 		int desc_size;

 		desc_size = identify_descriptor(desc, size);
 		if (desc_size <= 0) {
 			if (!desc_size)
 				pr_err("zero-sized manifest descriptor\n");
 			result = false;
 			goto out;
 		}
 		desc = (struct greybus_descriptor *)((char *)desc + desc_size);
 		size -= desc_size;
 	}

 	/* There must be a single module descriptor */
 	list_for_each_entry(descriptor, &manifest_descs, links) {
 		if (descriptor->type == GREYBUS_TYPE_MODULE)
 			if (!found++)
 				module_desc = descriptor;
 	}
 	if (found != 1) {
 		pr_err("manifest must have 1 module descriptor (%u found)\n",
 			found);
 		result = false;
 		goto out;
 	}

 	/* Parse the module manifest, starting with the module descriptor */
 	result = gb_manifest_parse_module(gmod, module_desc);

 	/*
 	 * We really should have no remaining descriptors, but we
 	 * don't know what newer format manifests might leave.
 	 */
 	if (!list_empty(&manifest_descs))
 		pr_info("excess descriptors in module manifest\n");
 out:
 	release_manifest_descriptors();

 	return result;
 }
	/*
	* Greybus module manifest parsing
	*
	* Copyright 2014 Google Inc.
	*
	* Released under the GPLv2 only.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/err.h>

	#include "greybus.h"

	/*
	* We scan the manifest once to identify where all the descriptors
	* are. The result is a list of these manifest_desc structures. We
	* then pick through them for what we're looking for (starting with
	* the module descriptor). As each is processed we remove it from
	* the list. When we're done the list should (probably) be empty.
	*/
	struct manifest_desc {
	struct list_head links;

	size_t size;
	void *data;
	enum greybus_descriptor_type type;
	};

	static LIST_HEAD(manifest_descs);

	static void release_manifest_descriptor(struct manifest_desc *descriptor)
	{
	list_del(&descriptor->links);
	kfree(descriptor);
	}

	static void release_manifest_descriptors(void)
	{
	struct manifest_desc *descriptor;
	struct manifest_desc *next;

	list_for_each_entry_safe(descriptor, next, &manifest_descs, links)
	release_manifest_descriptor(descriptor);
	}

	/*
	* Validate the given descriptor. Its reported size must fit within
	* the number of bytes reamining, and it must have a recognized
	* type. Check that the reported size is at least as big as what
	* we expect to see. (It could be bigger, perhaps for a new version
	* of the format.)
	*
	* Returns the number of bytes consumed by the descriptor, or a
	* negative errno.
	*/
	static int identify_descriptor(struct greybus_descriptor *desc, size_t size)
	{
	struct greybus_descriptor_header *desc_header = &desc->header;
	struct manifest_desc *descriptor;
	int desc_size;
	size_t expected_size;

	if (size < sizeof(*desc_header)) {
	pr_err("manifest too small\n");
	return -EINVAL; /* Must at least have header */
	}

	desc_size = (int)le16_to_cpu(desc_header->size);
	if ((size_t)desc_size > size) {
	pr_err("descriptor too big\n");
	return -EINVAL;
	}

	switch (desc_header->type) {
	case GREYBUS_TYPE_MODULE:
	if (desc_size < sizeof(struct greybus_descriptor_module)) {
	pr_err("module descriptor too small (%u)\n",
	desc_size);
	return -EINVAL;
	}
	break;
	case GREYBUS_TYPE_STRING:
	expected_size = sizeof(struct greybus_descriptor_header);
	expected_size += sizeof(struct greybus_descriptor_string);
	expected_size += (size_t)desc->string.length;
	if (desc_size < expected_size) {
	pr_err("string descriptor too small (%u)\n",
	desc_size);
	return -EINVAL;
	}
	break;
	case GREYBUS_TYPE_INTERFACE:
	break;
	case GREYBUS_TYPE_CPORT:
	if (desc_size < sizeof(struct greybus_descriptor_cport)) {
	pr_err("cport descriptor too small (%u)\n",
	desc_size);
	return -EINVAL;
	}
	break;
	case GREYBUS_TYPE_CLASS:
	pr_warn("class descriptor found (ignoring)\n");
	break;
	case GREYBUS_TYPE_INVALID:
	default:
	pr_err("invalid descriptor type (%hhu)\n", desc_header->type);
	return -EINVAL;
	}

	descriptor = kzalloc(sizeof(*descriptor), GFP_KERNEL);
	if (!descriptor)
	return -ENOMEM;

	descriptor->size = desc_size;
	descriptor->data = (u8 )desc + sizeof(desc_header);
	descriptor->type = desc_header->type;
	list_add_tail(&descriptor->links, &manifest_descs);

	return desc_size;
	}

	/*
	* Find the string descriptor having the given id, validate it, and
	* allocate a duplicate copy of it. The duplicate has an extra byte
	* which guarantees the returned string is NUL-terminated.
	*
	* String index 0 is valid (it represents "no string"), and for
	* that a null pointer is returned.
	*
	* Otherwise returns a pointer to a newly-allocated copy of the
	* descriptor string, or an error-coded pointer on failure.
	*/
	static char *gb_string_get(u8 string_id)
	{
	struct greybus_descriptor_string *desc_string;
	struct manifest_desc *descriptor;
	bool found = false;
	char *string;

	/* A zero string id means no string (but no error) */
	if (!string_id)
	return NULL;

	list_for_each_entry(descriptor, &manifest_descs, links) {

	if (descriptor->type != GREYBUS_TYPE_STRING)
	continue;

	desc_string = descriptor->data;
	if (desc_string->id == string_id) {
	found = true;
	break;
	}
	}
	if (!found)
	return ERR_PTR(-ENOENT);

	/* Allocate an extra byte so we can guarantee it's NUL-terminated */
	string = kmemdup(&desc_string->string, (size_t)desc_string->length + 1,
	GFP_KERNEL);
	if (!string)
	return ERR_PTR(-ENOMEM);
	string[desc_string->length] = '\0';

	/* Ok we've used this string, so we're done with it */
	release_manifest_descriptor(descriptor);

	return string;
	}

	/*
	* Find cport descriptors in the manifest and set up data structures
	* for the functions that use them. Returns the number of interfaces
	* set up for the given module, or 0 if there is an error.
	*/
	static u32 gb_manifest_parse_cports(struct gb_interface *interface)
	{
	u32 count = 0;

	while (true) {
	struct manifest_desc *descriptor;
	struct greybus_descriptor_cport *desc_cport;
	enum greybus_protocol protocol;
	u16 cport_id;
	bool found;

	/* Find a cport descriptor */
	found = false;
	list_for_each_entry(descriptor, &manifest_descs, links) {
	if (descriptor->type == GREYBUS_TYPE_CPORT) {
	desc_cport = descriptor->data;
	if (desc_cport->interface == interface->id) {
	found = true;
	break;
	}
	}
	}
	if (!found)
	break;

	/* Found one. Set up its function structure */
	protocol = (enum greybus_protocol)desc_cport->protocol;
	cport_id = le16_to_cpu(desc_cport->id);
	if (!gb_connection_create(interface, cport_id, protocol))
	return 0; /* Error */

	count++;
	/* Release the cport descriptor */
	release_manifest_descriptor(descriptor);
	}

	return count;
	}

	/*
	* Find interface descriptors in the manifest and set up their data
	* structures. Returns the number of interfaces set up for the
	* given module.
	*/
	static u32 gb_manifest_parse_interfaces(struct gb_module *gmod)
	{
	u32 count = 0;

	while (true) {
	struct manifest_desc *descriptor;
	struct greybus_descriptor_interface *desc_interface;
	struct gb_interface *interface;
	bool found = false;

	/* Find an interface descriptor */
	list_for_each_entry(descriptor, &manifest_descs, links) {
	if (descriptor->type == GREYBUS_TYPE_INTERFACE) {
	found = true;
	break;
	}
	}
	if (!found)
	break;

	/* Found one. Set up its interface structure*/
	desc_interface = descriptor->data;
	interface = gb_interface_create(gmod, desc_interface->id);
	if (!interface)
	return 0; /* Error */

	/* Now go set up this interface's functions and cports */
	if (!gb_manifest_parse_cports(interface))
	return 0; /* Error parsing cports */

	count++;

	/* Done with this interface descriptor */
	release_manifest_descriptor(descriptor);
	}

	return count;
	}

	static bool gb_manifest_parse_module(struct gb_module *gmod,
	struct manifest_desc *module_desc)
	{
	struct greybus_descriptor_module *desc_module = module_desc->data;

	/* Handle the strings first--they can fail */
	gmod->vendor_string = gb_string_get(desc_module->vendor_stringid);
	if (IS_ERR(gmod->vendor_string))
	return false;

	gmod->product_string = gb_string_get(desc_module->product_stringid);
	if (IS_ERR(gmod->product_string)) {
	goto out_err;
	}

	gmod->vendor = le16_to_cpu(desc_module->vendor);
	gmod->product = le16_to_cpu(desc_module->product);
	gmod->version = le16_to_cpu(desc_module->version);
	gmod->unique_id = le64_to_cpu(desc_module->unique_id);

	/* Release the module descriptor, now that we're done with it */
	release_manifest_descriptor(module_desc);

	/* A module must have at least one interface descriptor */
	if (!gb_manifest_parse_interfaces(gmod)) {
	pr_err("manifest interface descriptors not valid\n");
	goto out_err;
	}

	return true;
	out_err:
	kfree(gmod->product_string);
	gmod->product_string = NULL;
	kfree(gmod->vendor_string);
	gmod->vendor_string = NULL;

	return false;
	}

	/*
	* Parse a buffer containing a module manifest.
	*
	* If we find anything wrong with the content/format of the buffer
	* we reject it.
	*
	* The first requirement is that the manifest's version is
	* one we can parse.
	*
	* We make an initial pass through the buffer and identify all of
	* the descriptors it contains, keeping track for each its type
	* and the location size of its data in the buffer.
	*
	* Next we scan the descriptors, looking for a module descriptor;
	* there must be exactly one of those. When found, we record the
	* information it contains, and then remove that descriptor (and any
	* string descriptors it refers to) from further consideration.
	*
	* After that we look for the module's interfaces--there must be at
	* least one of those.
	*
	* Returns true if parsing was successful, false otherwise.
	*/
	bool gb_manifest_parse(struct gb_module gmod, void data, size_t size)
	{
	struct greybus_manifest *manifest;
	struct greybus_manifest_header *header;
	struct greybus_descriptor *desc;
	struct manifest_desc *descriptor;
	struct manifest_desc *module_desc = NULL;
	u16 manifest_size;
	u32 found = 0;
	bool result = false;

	/* we have to have at _least_ the manifest header */
	if (size <= sizeof(manifest->header)) {
	pr_err("short manifest (%zu)\n", size);
	return false;
	}

	/* Make sure the size is right */
	manifest = data;
	header = &manifest->header;
	manifest_size = le16_to_cpu(header->size);
	if (manifest_size != size) {
	pr_err("manifest size mismatch %zu != %hu\n",
	size, manifest_size);
	return false;
	}

	/* Validate major/minor number */
	if (header->version_major > GREYBUS_VERSION_MAJOR) {
	pr_err("manifest version too new (%hhu.%hhu > %hhu.%hhu)\n",
	header->version_major, header->version_minor,
	GREYBUS_VERSION_MAJOR, GREYBUS_VERSION_MINOR);
	return false;
	}

	/* OK, find all the descriptors */
	desc = (struct greybus_descriptor *)(header + 1);
	size -= sizeof(*header);
	while (size) {
	int desc_size;

	desc_size = identify_descriptor(desc, size);
	if (desc_size <= 0) {
	if (!desc_size)
	pr_err("zero-sized manifest descriptor\n");
	result = false;
	goto out;
	}
	desc = (struct greybus_descriptor )((char )desc + desc_size);
	size -= desc_size;
	}

	/* There must be a single module descriptor */
	list_for_each_entry(descriptor, &manifest_descs, links) {
	if (descriptor->type == GREYBUS_TYPE_MODULE)
	if (!found++)
	module_desc = descriptor;
	}
	if (found != 1) {
	pr_err("manifest must have 1 module descriptor (%u found)\n",
	found);
	result = false;
	goto out;
	}

	/* Parse the module manifest, starting with the module descriptor */
	result = gb_manifest_parse_module(gmod, module_desc);

	/*
	* We really should have no remaining descriptors, but we
	* don't know what newer format manifests might leave.
	*/
	if (!list_empty(&manifest_descs))
	pr_info("excess descriptors in module manifest\n");
	out:
	release_manifest_descriptors();

	return result;
	}