/*
* Greybus module manifest parsing
*
* Copyright 2014 Google Inc.
* Copyright 2014 Linaro Ltd.
*
* 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 void release_manifest_descriptor(struct manifest_desc *descriptor)
{
list_del(&descriptor->links);
kfree(descriptor);
}
static void release_manifest_descriptors(struct gb_interface *intf)
{
struct manifest_desc *descriptor;
struct manifest_desc *next;
list_for_each_entry_safe(descriptor, next, &intf->manifest_descs, links)
release_manifest_descriptor(descriptor);
}
/*
* Validate the given descriptor. Its reported size must fit within
* the number of bytes remaining, 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 gb_interface *intf,
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(*desc_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, &intf->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(struct gb_interface *intf, 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, &intf->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 bundles
* set up for the given interface, or 0 if there is an error.
*/
static u32 gb_manifest_parse_cports(struct gb_interface *intf,
struct gb_bundle *bundle)
{
u32 count = 0;
while (true) {
struct manifest_desc *descriptor;
struct greybus_descriptor_cport *desc_cport;
u8 protocol_id;
u16 cport_id;
bool found = false;
/* Find a cport descriptor */
list_for_each_entry(descriptor, &intf->manifest_descs, links) {
if (descriptor->type == GREYBUS_TYPE_CPORT) {
desc_cport = descriptor->data;
if (desc_cport->bundle == bundle->id) {
found = true;
break;
}
}
}
if (!found)
break;
/* Found one. Set up its function structure */
protocol_id = desc_cport->protocol_id;
cport_id = le16_to_cpu(desc_cport->id);
if (!gb_connection_create(bundle, cport_id, protocol_id))
return 0; /* Error */
count++;
/* Release the cport descriptor */
release_manifest_descriptor(descriptor);
}
return count;
}
/*
* Find bundle descriptors in the manifest and set up their data
* structures. Returns the number of bundles set up for the
* given module.
*/
static u32 gb_manifest_parse_bundles(struct gb_interface *intf)
{
u32 count = 0;
while (true) {
struct manifest_desc *descriptor;
struct greybus_descriptor_interface *desc_interface;
struct gb_bundle *bundle;
bool found = false;
/* Find an bundle descriptor */
list_for_each_entry(descriptor, &intf->manifest_descs, links) {
if (descriptor->type == GREYBUS_TYPE_INTERFACE) {
found = true;
break;
}
}
if (!found)
break;
/* Found one. Set up its bundle structure*/
desc_interface = descriptor->data;
bundle = gb_bundle_create(intf, desc_interface->id);
if (!bundle)
return 0; /* Error */
/* Now go set up this bundle's functions and cports */
if (!gb_manifest_parse_cports(intf, bundle))
return 0; /* Error parsing cports */
count++;
/* Done with this bundle descriptor */
release_manifest_descriptor(descriptor);
}
return count;
}
static bool gb_manifest_parse_module(struct gb_interface *intf,
struct manifest_desc *module_desc)
{
struct greybus_descriptor_module *desc_module = module_desc->data;
/* Handle the strings first--they can fail */
intf->vendor_string = gb_string_get(intf, desc_module->vendor_stringid);
if (IS_ERR(intf->vendor_string))
return false;
intf->product_string = gb_string_get(intf,
desc_module->product_stringid);
if (IS_ERR(intf->product_string)) {
goto out_free_vendor_string;
}
intf->vendor = le16_to_cpu(desc_module->vendor);
intf->product = le16_to_cpu(desc_module->product);
intf->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);
/* An interface must have at least one bundle descriptor */
if (!gb_manifest_parse_bundles(intf)) {
pr_err("manifest bundle descriptors not valid\n");
goto out_err;
}
return true;
out_err:
kfree(intf->product_string);
intf->product_string = NULL;
out_free_vendor_string:
kfree(intf->vendor_string);
intf->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 interface's bundles--there must be at
* least one of those.
*
* Returns true if parsing was successful, false otherwise.
*/
bool gb_manifest_parse(struct gb_interface *intf, 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;
/* Manifest descriptor list should be empty here */
if (WARN_ON(!list_empty(&intf->manifest_descs)))
return 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(intf, 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, &intf->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(intf, module_desc);
/*
* We really should have no remaining descriptors, but we
* don't know what newer format manifests might leave.
*/
if (result && !list_empty(&intf->manifest_descs))
pr_info("excess descriptors in module manifest\n");
out:
release_manifest_descriptors(intf);
return result;
}
