/*
* 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 = desc;
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) {
struct greybus_descriptor *desc;
if (descriptor->type != GREYBUS_TYPE_STRING)
continue;
desc = descriptor->data;
desc_string = &desc->string;
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 *desc = module_desc->data;
struct greybus_descriptor_module *desc_module = &desc->module;
/* 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");
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);
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 false;
}
