148 lines
3.4 KiB
C
148 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Support for extracting embedded firmware for peripherals from EFI code,
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*
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* Copyright (c) 2018 Hans de Goede <hdegoede@redhat.com>
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*/
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#include <linux/dmi.h>
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#include <linux/efi.h>
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#include <linux/efi_embedded_fw.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/vmalloc.h>
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#include <crypto/sha2.h>
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/* Exported for use by lib/test_firmware.c only */
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LIST_HEAD(efi_embedded_fw_list);
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EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_list, TEST_FIRMWARE);
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bool efi_embedded_fw_checked;
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EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_checked, TEST_FIRMWARE);
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static const struct dmi_system_id * const embedded_fw_table[] = {
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#ifdef CONFIG_TOUCHSCREEN_DMI
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touchscreen_dmi_table,
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#endif
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NULL
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};
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/*
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* Note the efi_check_for_embedded_firmwares() code currently makes the
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* following 2 assumptions. This may needs to be revisited if embedded firmware
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* is found where this is not true:
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* 1) The firmware is only found in EFI_BOOT_SERVICES_CODE memory segments
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* 2) The firmware always starts at an offset which is a multiple of 8 bytes
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*/
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static int __init efi_check_md_for_embedded_firmware(
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efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc)
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{
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struct efi_embedded_fw *fw;
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u8 hash[32];
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u64 i, size;
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u8 *map;
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size = md->num_pages << EFI_PAGE_SHIFT;
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map = memremap(md->phys_addr, size, MEMREMAP_WB);
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if (!map) {
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pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr);
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return -ENOMEM;
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}
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for (i = 0; (i + desc->length) <= size; i += 8) {
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if (memcmp(map + i, desc->prefix, EFI_EMBEDDED_FW_PREFIX_LEN))
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continue;
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sha256(map + i, desc->length, hash);
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if (memcmp(hash, desc->sha256, 32) == 0)
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break;
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}
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if ((i + desc->length) > size) {
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memunmap(map);
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return -ENOENT;
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}
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pr_info("Found EFI embedded fw '%s'\n", desc->name);
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fw = kmalloc(sizeof(*fw), GFP_KERNEL);
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if (!fw) {
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memunmap(map);
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return -ENOMEM;
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}
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fw->data = kmemdup(map + i, desc->length, GFP_KERNEL);
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memunmap(map);
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if (!fw->data) {
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kfree(fw);
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return -ENOMEM;
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}
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fw->name = desc->name;
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fw->length = desc->length;
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list_add(&fw->list, &efi_embedded_fw_list);
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return 0;
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}
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void __init efi_check_for_embedded_firmwares(void)
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{
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const struct efi_embedded_fw_desc *fw_desc;
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const struct dmi_system_id *dmi_id;
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efi_memory_desc_t *md;
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int i, r;
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for (i = 0; embedded_fw_table[i]; i++) {
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dmi_id = dmi_first_match(embedded_fw_table[i]);
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if (!dmi_id)
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continue;
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fw_desc = dmi_id->driver_data;
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/*
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* In some drivers the struct driver_data contains may contain
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* other driver specific data after the fw_desc struct; and
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* the fw_desc struct itself may be empty, skip these.
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*/
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if (!fw_desc->name)
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continue;
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for_each_efi_memory_desc(md) {
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if (md->type != EFI_BOOT_SERVICES_CODE)
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continue;
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r = efi_check_md_for_embedded_firmware(md, fw_desc);
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if (r == 0)
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break;
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}
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}
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efi_embedded_fw_checked = true;
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}
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int efi_get_embedded_fw(const char *name, const u8 **data, size_t *size)
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{
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struct efi_embedded_fw *iter, *fw = NULL;
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if (!efi_embedded_fw_checked) {
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pr_warn("Warning %s called while we did not check for embedded fw\n",
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__func__);
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return -ENOENT;
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}
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list_for_each_entry(iter, &efi_embedded_fw_list, list) {
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if (strcmp(name, iter->name) == 0) {
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fw = iter;
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break;
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}
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}
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if (!fw)
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return -ENOENT;
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*data = fw->data;
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*size = fw->length;
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return 0;
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}
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EXPORT_SYMBOL_GPL(efi_get_embedded_fw);
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