void __init efi_mokvar_table_init()

in efi/mokvar-table.c [100:188]

• 60 lines of code
• 14 McCabe index (conditional complexity)

void __init efi_mokvar_table_init(void)
{
	efi_memory_desc_t md;
	void *va = NULL;
	unsigned long cur_offset = 0;
	unsigned long offset_limit;
	unsigned long map_size = 0;
	unsigned long map_size_needed = 0;
	unsigned long size;
	struct efi_mokvar_table_entry *mokvar_entry;
	int err;

	if (!efi_enabled(EFI_MEMMAP))
		return;

	if (efi.mokvar_table == EFI_INVALID_TABLE_ADDR)
		return;
	/*
	 * The EFI MOK config table must fit within a single EFI memory
	 * descriptor range.
	 */
	err = efi_mem_desc_lookup(efi.mokvar_table, &md);
	if (err) {
		pr_warn("EFI MOKvar config table is not within the EFI memory map\n");
		return;
	}

	offset_limit = efi_mem_desc_end(&md) - efi.mokvar_table;

	/*
	 * Validate the MOK config table. Since there is no table header
	 * from which we could get the total size of the MOK config table,
	 * we compute the total size as we validate each variably sized
	 * entry, remapping as necessary.
	 */
	err = -EINVAL;
	while (cur_offset + sizeof(*mokvar_entry) <= offset_limit) {
		mokvar_entry = va + cur_offset;
		map_size_needed = cur_offset + sizeof(*mokvar_entry);
		if (map_size_needed > map_size) {
			if (va)
				early_memunmap(va, map_size);
			/*
			 * Map a little more than the fixed size entry
			 * header, anticipating some data. It's safe to
			 * do so as long as we stay within current memory
			 * descriptor.
			 */
			map_size = min(map_size_needed + 2*EFI_PAGE_SIZE,
				       offset_limit);
			va = early_memremap(efi.mokvar_table, map_size);
			if (!va) {
				pr_err("Failed to map EFI MOKvar config table pa=0x%lx, size=%lu.\n",
				       efi.mokvar_table, map_size);
				return;
			}
			mokvar_entry = va + cur_offset;
		}

		/* Check for last sentinel entry */
		if (mokvar_entry->name[0] == '\0') {
			if (mokvar_entry->data_size != 0)
				break;
			err = 0;
			break;
		}

		/* Sanity check that the name is null terminated */
		size = strnlen(mokvar_entry->name,
			       sizeof(mokvar_entry->name));
		if (size >= sizeof(mokvar_entry->name))
			break;

		/* Advance to the next entry */
		cur_offset = map_size_needed + mokvar_entry->data_size;
	}

	if (va)
		early_memunmap(va, map_size);
	if (err) {
		pr_err("EFI MOKvar config table is not valid\n");
		return;
	}

	if (md.type == EFI_BOOT_SERVICES_DATA)
		efi_mem_reserve(efi.mokvar_table, map_size_needed);

	efi_mokvar_table_size = map_size_needed;
}