1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Support for extracting embedded firmware for peripherals from EFI code, 4 * 5 * Copyright (c) 2018 Hans de Goede <hdegoede@redhat.com> 6 */ 7 8 #include <linux/dmi.h> 9 #include <linux/efi.h> 10 #include <linux/efi_embedded_fw.h> 11 #include <linux/io.h> 12 #include <linux/slab.h> 13 #include <linux/types.h> 14 #include <linux/vmalloc.h> 15 #include <crypto/sha2.h> 16 17 /* Exported for use by lib/test_firmware.c only */ 18 LIST_HEAD(efi_embedded_fw_list); 19 EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_list, TEST_FIRMWARE); 20 bool efi_embedded_fw_checked; 21 EXPORT_SYMBOL_NS_GPL(efi_embedded_fw_checked, TEST_FIRMWARE); 22 23 static const struct dmi_system_id * const embedded_fw_table[] = { 24 #ifdef CONFIG_TOUCHSCREEN_DMI 25 touchscreen_dmi_table, 26 #endif 27 NULL 28 }; 29 30 /* 31 * Note the efi_check_for_embedded_firmwares() code currently makes the 32 * following 2 assumptions. This may needs to be revisited if embedded firmware 33 * is found where this is not true: 34 * 1) The firmware is only found in EFI_BOOT_SERVICES_CODE memory segments 35 * 2) The firmware always starts at an offset which is a multiple of 8 bytes 36 */ 37 static int __init efi_check_md_for_embedded_firmware( 38 efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc) 39 { 40 struct efi_embedded_fw *fw; 41 u8 hash[32]; 42 u64 i, size; 43 u8 *map; 44 45 size = md->num_pages << EFI_PAGE_SHIFT; 46 map = memremap(md->phys_addr, size, MEMREMAP_WB); 47 if (!map) { 48 pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr); 49 return -ENOMEM; 50 } 51 52 for (i = 0; (i + desc->length) <= size; i += 8) { 53 if (memcmp(map + i, desc->prefix, EFI_EMBEDDED_FW_PREFIX_LEN)) 54 continue; 55 56 sha256(map + i, desc->length, hash); 57 if (memcmp(hash, desc->sha256, 32) == 0) 58 break; 59 } 60 if ((i + desc->length) > size) { 61 memunmap(map); 62 return -ENOENT; 63 } 64 65 pr_info("Found EFI embedded fw '%s'\n", desc->name); 66 67 fw = kmalloc(sizeof(*fw), GFP_KERNEL); 68 if (!fw) { 69 memunmap(map); 70 return -ENOMEM; 71 } 72 73 fw->data = kmemdup(map + i, desc->length, GFP_KERNEL); 74 memunmap(map); 75 if (!fw->data) { 76 kfree(fw); 77 return -ENOMEM; 78 } 79 80 fw->name = desc->name; 81 fw->length = desc->length; 82 list_add(&fw->list, &efi_embedded_fw_list); 83 84 return 0; 85 } 86 87 void __init efi_check_for_embedded_firmwares(void) 88 { 89 const struct efi_embedded_fw_desc *fw_desc; 90 const struct dmi_system_id *dmi_id; 91 efi_memory_desc_t *md; 92 int i, r; 93 94 for (i = 0; embedded_fw_table[i]; i++) { 95 dmi_id = dmi_first_match(embedded_fw_table[i]); 96 if (!dmi_id) 97 continue; 98 99 fw_desc = dmi_id->driver_data; 100 101 /* 102 * In some drivers the struct driver_data contains may contain 103 * other driver specific data after the fw_desc struct; and 104 * the fw_desc struct itself may be empty, skip these. 105 */ 106 if (!fw_desc->name) 107 continue; 108 109 for_each_efi_memory_desc(md) { 110 if (md->type != EFI_BOOT_SERVICES_CODE) 111 continue; 112 113 r = efi_check_md_for_embedded_firmware(md, fw_desc); 114 if (r == 0) 115 break; 116 } 117 } 118 119 efi_embedded_fw_checked = true; 120 } 121 122 int efi_get_embedded_fw(const char *name, const u8 **data, size_t *size) 123 { 124 struct efi_embedded_fw *iter, *fw = NULL; 125 126 if (!efi_embedded_fw_checked) { 127 pr_warn("Warning %s called while we did not check for embedded fw\n", 128 __func__); 129 return -ENOENT; 130 } 131 132 list_for_each_entry(iter, &efi_embedded_fw_list, list) { 133 if (strcmp(name, iter->name) == 0) { 134 fw = iter; 135 break; 136 } 137 } 138 139 if (!fw) 140 return -ENOENT; 141 142 *data = fw->data; 143 *size = fw->length; 144 145 return 0; 146 } 147 EXPORT_SYMBOL_GPL(efi_get_embedded_fw); 148