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(offset: md->phys_addr, size, flags: 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(p: map + i, q: desc->prefix, EFI_EMBEDDED_FW_PREFIX_LEN)) |
54 | continue; |
55 | |
56 | sha256(data: map + i, len: desc->length, out: hash); |
57 | if (memcmp(p: hash, q: desc->sha256, size: 32) == 0) |
58 | break; |
59 | } |
60 | if ((i + desc->length) > size) { |
61 | memunmap(addr: map); |
62 | return -ENOENT; |
63 | } |
64 | |
65 | pr_info("Found EFI embedded fw '%s'\n" , desc->name); |
66 | |
67 | fw = kmalloc(size: sizeof(*fw), GFP_KERNEL); |
68 | if (!fw) { |
69 | memunmap(addr: map); |
70 | return -ENOMEM; |
71 | } |
72 | |
73 | fw->data = kmemdup(p: map + i, size: desc->length, GFP_KERNEL); |
74 | memunmap(addr: map); |
75 | if (!fw->data) { |
76 | kfree(objp: fw); |
77 | return -ENOMEM; |
78 | } |
79 | |
80 | fw->name = desc->name; |
81 | fw->length = desc->length; |
82 | list_add(new: &fw->list, head: &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(list: 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, desc: 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 | |