1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * EFI boot manager
4 *
5 * Copyright (c) 2017 Rob Clark
6 */
7
8 #define LOG_CATEGORY LOGC_EFI
9
10 #include <common.h>
11 #include <charset.h>
12 #include <log.h>
13 #include <malloc.h>
14 #include <efi_loader.h>
15 #include <efi_variable.h>
16 #include <asm/unaligned.h>
17
18 static const struct efi_boot_services *bs;
19 static const struct efi_runtime_services *rs;
20
21 /*
22 * bootmgr implements the logic of trying to find a payload to boot
23 * based on the BootOrder + BootXXXX variables, and then loading it.
24 *
25 * TODO detecting a special key held (f9?) and displaying a boot menu
26 * like you would get on a PC would be clever.
27 *
28 * TODO if we had a way to write and persist variables after the OS
29 * has started, we'd also want to check OsIndications to see if we
30 * should do normal or recovery boot.
31 */
32
33 /**
34 * get_var() - get UEFI variable
35 *
36 * It is the caller's duty to free the returned buffer.
37 *
38 * @name: name of variable
39 * @vendor: vendor GUID of variable
40 * @size: size of allocated buffer
41 * Return: buffer with variable data or NULL
42 */
get_var(u16 * name,const efi_guid_t * vendor,efi_uintn_t * size)43 static void *get_var(u16 *name, const efi_guid_t *vendor,
44 efi_uintn_t *size)
45 {
46 efi_status_t ret;
47 void *buf = NULL;
48
49 *size = 0;
50 ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
51 if (ret == EFI_BUFFER_TOO_SMALL) {
52 buf = malloc(*size);
53 ret = efi_get_variable_int(name, vendor, NULL, size, buf, NULL);
54 }
55
56 if (ret != EFI_SUCCESS) {
57 free(buf);
58 *size = 0;
59 return NULL;
60 }
61
62 return buf;
63 }
64
65 /**
66 * try_load_entry() - try to load image for boot option
67 *
68 * Attempt to load load-option number 'n', returning device_path and file_path
69 * if successful. This checks that the EFI_LOAD_OPTION is active (enabled)
70 * and that the specified file to boot exists.
71 *
72 * @n: number of the boot option, e.g. 0x0a13 for Boot0A13
73 * @handle: on return handle for the newly installed image
74 * @load_options: load options set on the loaded image protocol
75 * Return: status code
76 */
try_load_entry(u16 n,efi_handle_t * handle,void ** load_options)77 static efi_status_t try_load_entry(u16 n, efi_handle_t *handle,
78 void **load_options)
79 {
80 struct efi_load_option lo;
81 u16 varname[] = L"Boot0000";
82 u16 hexmap[] = L"0123456789ABCDEF";
83 void *load_option;
84 efi_uintn_t size;
85 efi_status_t ret;
86
87 varname[4] = hexmap[(n & 0xf000) >> 12];
88 varname[5] = hexmap[(n & 0x0f00) >> 8];
89 varname[6] = hexmap[(n & 0x00f0) >> 4];
90 varname[7] = hexmap[(n & 0x000f) >> 0];
91
92 load_option = get_var(varname, &efi_global_variable_guid, &size);
93 if (!load_option)
94 return EFI_LOAD_ERROR;
95
96 ret = efi_deserialize_load_option(&lo, load_option, &size);
97 if (ret != EFI_SUCCESS) {
98 log_warning("Invalid load option for %ls\n", varname);
99 goto error;
100 }
101
102 if (lo.attributes & LOAD_OPTION_ACTIVE) {
103 u32 attributes;
104
105 log_debug("%s: trying to load \"%ls\" from %pD\n",
106 __func__, lo.label, lo.file_path);
107
108 ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
109 NULL, 0, handle));
110 if (ret != EFI_SUCCESS) {
111 log_warning("Loading %ls '%ls' failed\n",
112 varname, lo.label);
113 goto error;
114 }
115
116 attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
117 EFI_VARIABLE_RUNTIME_ACCESS;
118 ret = efi_set_variable_int(L"BootCurrent",
119 &efi_global_variable_guid,
120 attributes, sizeof(n), &n, false);
121 if (ret != EFI_SUCCESS) {
122 if (EFI_CALL(efi_unload_image(*handle))
123 != EFI_SUCCESS)
124 log_err("Unloading image failed\n");
125 goto error;
126 }
127
128 log_info("Booting: %ls\n", lo.label);
129 } else {
130 ret = EFI_LOAD_ERROR;
131 }
132
133 /* Set load options */
134 if (size) {
135 *load_options = malloc(size);
136 if (!*load_options) {
137 ret = EFI_OUT_OF_RESOURCES;
138 goto error;
139 }
140 memcpy(*load_options, lo.optional_data, size);
141 ret = efi_set_load_options(*handle, size, *load_options);
142 } else {
143 *load_options = NULL;
144 }
145
146 error:
147 free(load_option);
148
149 return ret;
150 }
151
152 /**
153 * efi_bootmgr_load() - try to load from BootNext or BootOrder
154 *
155 * Attempt to load from BootNext or in the order specified by BootOrder
156 * EFI variable, the available load-options, finding and returning
157 * the first one that can be loaded successfully.
158 *
159 * @handle: on return handle for the newly installed image
160 * @load_options: load options set on the loaded image protocol
161 * Return: status code
162 */
efi_bootmgr_load(efi_handle_t * handle,void ** load_options)163 efi_status_t efi_bootmgr_load(efi_handle_t *handle, void **load_options)
164 {
165 u16 bootnext, *bootorder;
166 efi_uintn_t size;
167 int i, num;
168 efi_status_t ret;
169
170 bs = systab.boottime;
171 rs = systab.runtime;
172
173 /* BootNext */
174 size = sizeof(bootnext);
175 ret = efi_get_variable_int(L"BootNext",
176 &efi_global_variable_guid,
177 NULL, &size, &bootnext, NULL);
178 if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
179 /* BootNext does exist here */
180 if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
181 log_err("BootNext must be 16-bit integer\n");
182
183 /* delete BootNext */
184 ret = efi_set_variable_int(L"BootNext",
185 &efi_global_variable_guid,
186 0, 0, NULL, false);
187
188 /* load BootNext */
189 if (ret == EFI_SUCCESS) {
190 if (size == sizeof(u16)) {
191 ret = try_load_entry(bootnext, handle,
192 load_options);
193 if (ret == EFI_SUCCESS)
194 return ret;
195 log_warning(
196 "Loading from BootNext failed, falling back to BootOrder\n");
197 }
198 } else {
199 log_err("Deleting BootNext failed\n");
200 }
201 }
202
203 /* BootOrder */
204 bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
205 if (!bootorder) {
206 log_info("BootOrder not defined\n");
207 ret = EFI_NOT_FOUND;
208 goto error;
209 }
210
211 num = size / sizeof(uint16_t);
212 for (i = 0; i < num; i++) {
213 log_debug("%s trying to load Boot%04X\n", __func__,
214 bootorder[i]);
215 ret = try_load_entry(bootorder[i], handle, load_options);
216 if (ret == EFI_SUCCESS)
217 break;
218 }
219
220 free(bootorder);
221
222 error:
223 return ret;
224 }
225