1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * UEFI runtime variable services
4 *
5 * Copyright (c) 2017 Rob Clark
6 */
7
8 #define LOG_CATEGORY LOGC_EFI
9
10 #include <common.h>
11 #include <efi_loader.h>
12 #include <efi_variable.h>
13 #include <env.h>
14 #include <env_internal.h>
15 #include <hexdump.h>
16 #include <log.h>
17 #include <malloc.h>
18 #include <rtc.h>
19 #include <search.h>
20 #include <uuid.h>
21 #include <crypto/pkcs7_parser.h>
22 #include <linux/compat.h>
23 #include <u-boot/crc.h>
24 #include <asm/sections.h>
25
26 #ifdef CONFIG_EFI_SECURE_BOOT
27
28 /**
29 * efi_variable_authenticate - authenticate a variable
30 * @variable: Variable name in u16
31 * @vendor: Guid of variable
32 * @data_size: Size of @data
33 * @data: Pointer to variable's value
34 * @given_attr: Attributes to be given at SetVariable()
35 * @env_attr: Attributes that an existing variable holds
36 * @time: signed time that an existing variable holds
37 *
38 * Called by efi_set_variable() to verify that the input is correct.
39 * Will replace the given data pointer with another that points to
40 * the actual data to store in the internal memory.
41 * On success, @data and @data_size will be replaced with variable's
42 * actual data, excluding authentication data, and its size, and variable's
43 * attributes and signed time will also be returned in @env_attr and @time,
44 * respectively.
45 *
46 * Return: status code
47 */
efi_variable_authenticate(const u16 * variable,const efi_guid_t * vendor,efi_uintn_t * data_size,const void ** data,u32 given_attr,u32 * env_attr,u64 * time)48 static efi_status_t efi_variable_authenticate(const u16 *variable,
49 const efi_guid_t *vendor,
50 efi_uintn_t *data_size,
51 const void **data, u32 given_attr,
52 u32 *env_attr, u64 *time)
53 {
54 const struct efi_variable_authentication_2 *auth;
55 struct efi_signature_store *truststore, *truststore2;
56 struct pkcs7_message *var_sig;
57 struct efi_image_regions *regs;
58 struct efi_time timestamp;
59 struct rtc_time tm;
60 u64 new_time;
61 u8 *ebuf;
62 enum efi_auth_var_type var_type;
63 efi_status_t ret;
64
65 var_sig = NULL;
66 truststore = NULL;
67 truststore2 = NULL;
68 regs = NULL;
69 ebuf = NULL;
70 ret = EFI_SECURITY_VIOLATION;
71
72 if (*data_size < sizeof(struct efi_variable_authentication_2))
73 goto err;
74
75 /* authentication data */
76 auth = *data;
77 if (*data_size < (sizeof(auth->time_stamp)
78 + auth->auth_info.hdr.dwLength))
79 goto err;
80
81 if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
82 goto err;
83
84 memcpy(×tamp, &auth->time_stamp, sizeof(timestamp));
85 if (timestamp.pad1 || timestamp.nanosecond || timestamp.timezone ||
86 timestamp.daylight || timestamp.pad2)
87 goto err;
88
89 *data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
90 *data_size -= (sizeof(auth->time_stamp)
91 + auth->auth_info.hdr.dwLength);
92
93 memset(&tm, 0, sizeof(tm));
94 tm.tm_year = timestamp.year;
95 tm.tm_mon = timestamp.month;
96 tm.tm_mday = timestamp.day;
97 tm.tm_hour = timestamp.hour;
98 tm.tm_min = timestamp.minute;
99 tm.tm_sec = timestamp.second;
100 new_time = rtc_mktime(&tm);
101
102 if (!efi_secure_boot_enabled()) {
103 /* finished checking */
104 *time = new_time;
105 return EFI_SUCCESS;
106 }
107
108 if (new_time <= *time)
109 goto err;
110
111 /* data to be digested */
112 regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
113 if (!regs)
114 goto err;
115 regs->max = 5;
116 efi_image_region_add(regs, (uint8_t *)variable,
117 (uint8_t *)variable
118 + u16_strlen(variable) * sizeof(u16), 1);
119 efi_image_region_add(regs, (uint8_t *)vendor,
120 (uint8_t *)vendor + sizeof(*vendor), 1);
121 efi_image_region_add(regs, (uint8_t *)&given_attr,
122 (uint8_t *)&given_attr + sizeof(given_attr), 1);
123 efi_image_region_add(regs, (uint8_t *)×tamp,
124 (uint8_t *)×tamp + sizeof(timestamp), 1);
125 efi_image_region_add(regs, (uint8_t *)*data,
126 (uint8_t *)*data + *data_size, 1);
127
128 /* variable's signature list */
129 if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
130 goto err;
131
132 /* ebuf should be kept valid during the authentication */
133 var_sig = efi_parse_pkcs7_header(auth->auth_info.cert_data,
134 auth->auth_info.hdr.dwLength
135 - sizeof(auth->auth_info),
136 &ebuf);
137 if (!var_sig) {
138 EFI_PRINT("Parsing variable's signature failed\n");
139 goto err;
140 }
141
142 /* signature database used for authentication */
143 var_type = efi_auth_var_get_type(variable, vendor);
144 switch (var_type) {
145 case EFI_AUTH_VAR_PK:
146 case EFI_AUTH_VAR_KEK:
147 /* with PK */
148 truststore = efi_sigstore_parse_sigdb(u"PK");
149 if (!truststore)
150 goto err;
151 break;
152 case EFI_AUTH_VAR_DB:
153 case EFI_AUTH_VAR_DBX:
154 /* with PK and KEK */
155 truststore = efi_sigstore_parse_sigdb(u"KEK");
156 truststore2 = efi_sigstore_parse_sigdb(u"PK");
157 if (!truststore) {
158 if (!truststore2)
159 goto err;
160
161 truststore = truststore2;
162 truststore2 = NULL;
163 }
164 break;
165 default:
166 /* TODO: support private authenticated variables */
167 goto err;
168 }
169
170 /* verify signature */
171 if (efi_signature_verify(regs, var_sig, truststore, NULL)) {
172 EFI_PRINT("Verified\n");
173 } else {
174 if (truststore2 &&
175 efi_signature_verify(regs, var_sig, truststore2, NULL)) {
176 EFI_PRINT("Verified\n");
177 } else {
178 EFI_PRINT("Verifying variable's signature failed\n");
179 goto err;
180 }
181 }
182
183 /* finished checking */
184 *time = new_time;
185 ret = EFI_SUCCESS;
186
187 err:
188 efi_sigstore_free(truststore);
189 efi_sigstore_free(truststore2);
190 pkcs7_free_message(var_sig);
191 free(ebuf);
192 free(regs);
193
194 return ret;
195 }
196 #else
efi_variable_authenticate(const u16 * variable,const efi_guid_t * vendor,efi_uintn_t * data_size,const void ** data,u32 given_attr,u32 * env_attr,u64 * time)197 static efi_status_t efi_variable_authenticate(const u16 *variable,
198 const efi_guid_t *vendor,
199 efi_uintn_t *data_size,
200 const void **data, u32 given_attr,
201 u32 *env_attr, u64 *time)
202 {
203 return EFI_SUCCESS;
204 }
205 #endif /* CONFIG_EFI_SECURE_BOOT */
206
207 efi_status_t __efi_runtime
efi_get_variable_int(const u16 * variable_name,const efi_guid_t * vendor,u32 * attributes,efi_uintn_t * data_size,void * data,u64 * timep)208 efi_get_variable_int(const u16 *variable_name, const efi_guid_t *vendor,
209 u32 *attributes, efi_uintn_t *data_size, void *data,
210 u64 *timep)
211 {
212 return efi_get_variable_mem(variable_name, vendor, attributes, data_size, data, timep);
213 }
214
215 efi_status_t __efi_runtime
efi_get_next_variable_name_int(efi_uintn_t * variable_name_size,u16 * variable_name,efi_guid_t * vendor)216 efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
217 u16 *variable_name, efi_guid_t *vendor)
218 {
219 return efi_get_next_variable_name_mem(variable_name_size, variable_name, vendor);
220 }
221
efi_set_variable_int(const u16 * variable_name,const efi_guid_t * vendor,u32 attributes,efi_uintn_t data_size,const void * data,bool ro_check)222 efi_status_t efi_set_variable_int(const u16 *variable_name,
223 const efi_guid_t *vendor,
224 u32 attributes, efi_uintn_t data_size,
225 const void *data, bool ro_check)
226 {
227 struct efi_var_entry *var;
228 efi_uintn_t ret;
229 bool append, delete;
230 u64 time = 0;
231 enum efi_auth_var_type var_type;
232
233 if (!variable_name || !*variable_name || !vendor)
234 return EFI_INVALID_PARAMETER;
235
236 if (data_size && !data)
237 return EFI_INVALID_PARAMETER;
238
239 /* EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated */
240 if (attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
241 return EFI_UNSUPPORTED;
242
243 /* Make sure if runtime bit is set, boot service bit is set also */
244 if ((attributes &
245 (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)) ==
246 EFI_VARIABLE_RUNTIME_ACCESS)
247 return EFI_INVALID_PARAMETER;
248
249 /* only EFI_VARIABLE_NON_VOLATILE attribute is invalid */
250 if ((attributes & EFI_VARIABLE_MASK) == EFI_VARIABLE_NON_VOLATILE)
251 return EFI_INVALID_PARAMETER;
252
253 /* Make sure HR is set with NV, BS and RT */
254 if (attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD &&
255 (!(attributes & EFI_VARIABLE_NON_VOLATILE) ||
256 !(attributes & EFI_VARIABLE_RUNTIME_ACCESS) ||
257 !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)))
258 return EFI_INVALID_PARAMETER;
259
260 /* check if a variable exists */
261 var = efi_var_mem_find(vendor, variable_name, NULL);
262 append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
263 attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
264 delete = !append && (!data_size || !attributes);
265
266 /* check attributes */
267 var_type = efi_auth_var_get_type(variable_name, vendor);
268 if (var) {
269 if (ro_check && (var->attr & EFI_VARIABLE_READ_ONLY))
270 return EFI_WRITE_PROTECTED;
271
272 if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
273 if (var_type >= EFI_AUTH_VAR_PK)
274 return EFI_WRITE_PROTECTED;
275 }
276
277 /* attributes won't be changed */
278 if (!delete &&
279 ((ro_check && var->attr != attributes) ||
280 (!ro_check && ((var->attr & ~(u32)EFI_VARIABLE_READ_ONLY)
281 != (attributes & ~(u32)EFI_VARIABLE_READ_ONLY))))) {
282 return EFI_INVALID_PARAMETER;
283 }
284 time = var->time;
285 } else {
286 if (delete || append)
287 /*
288 * Trying to delete or to update a non-existent
289 * variable.
290 */
291 return EFI_NOT_FOUND;
292 }
293
294 if (var_type >= EFI_AUTH_VAR_PK) {
295 /* authentication is mandatory */
296 if (!(attributes &
297 EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
298 EFI_PRINT("%ls: TIME_BASED_AUTHENTICATED_WRITE_ACCESS required\n",
299 variable_name);
300 return EFI_INVALID_PARAMETER;
301 }
302 }
303
304 /* authenticate a variable */
305 if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
306 if (attributes &
307 EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
308 u32 env_attr;
309
310 ret = efi_variable_authenticate(variable_name, vendor,
311 &data_size, &data,
312 attributes, &env_attr,
313 &time);
314 if (ret != EFI_SUCCESS)
315 return ret;
316
317 /* last chance to check for delete */
318 if (!data_size)
319 delete = true;
320 }
321 } else {
322 if (attributes &
323 EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
324 EFI_PRINT("Secure boot is not configured\n");
325 return EFI_INVALID_PARAMETER;
326 }
327 }
328
329 if (delete) {
330 /* EFI_NOT_FOUND has been handled before */
331 attributes = var->attr;
332 ret = EFI_SUCCESS;
333 } else if (append) {
334 u16 *old_data = var->name;
335
336 for (; *old_data; ++old_data)
337 ;
338 ++old_data;
339 ret = efi_var_mem_ins(variable_name, vendor, attributes,
340 var->length, old_data, data_size, data,
341 time);
342 } else {
343 ret = efi_var_mem_ins(variable_name, vendor, attributes,
344 data_size, data, 0, NULL, time);
345 }
346 efi_var_mem_del(var);
347
348 if (ret != EFI_SUCCESS)
349 return ret;
350
351 if (var_type == EFI_AUTH_VAR_PK)
352 ret = efi_init_secure_state();
353 else
354 ret = EFI_SUCCESS;
355
356 /*
357 * Write non-volatile EFI variables to file
358 * TODO: check if a value change has occured to avoid superfluous writes
359 */
360 if (attributes & EFI_VARIABLE_NON_VOLATILE)
361 efi_var_to_file();
362
363 return EFI_SUCCESS;
364 }
365
efi_query_variable_info_int(u32 attributes,u64 * maximum_variable_storage_size,u64 * remaining_variable_storage_size,u64 * maximum_variable_size)366 efi_status_t efi_query_variable_info_int(u32 attributes,
367 u64 *maximum_variable_storage_size,
368 u64 *remaining_variable_storage_size,
369 u64 *maximum_variable_size)
370 {
371 if (attributes == 0)
372 return EFI_INVALID_PARAMETER;
373
374 /* EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS is deprecated */
375 if ((attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS) ||
376 ((attributes & EFI_VARIABLE_MASK) == 0))
377 return EFI_UNSUPPORTED;
378
379 if ((attributes & EFI_VARIABLE_MASK) == EFI_VARIABLE_NON_VOLATILE)
380 return EFI_INVALID_PARAMETER;
381
382 /* Make sure if runtime bit is set, boot service bit is set also. */
383 if ((attributes &
384 (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)) ==
385 EFI_VARIABLE_RUNTIME_ACCESS)
386 return EFI_INVALID_PARAMETER;
387
388 if (attributes & ~(u32)EFI_VARIABLE_MASK)
389 return EFI_INVALID_PARAMETER;
390
391 *maximum_variable_storage_size = EFI_VAR_BUF_SIZE -
392 sizeof(struct efi_var_file);
393 *remaining_variable_storage_size = efi_var_mem_free();
394 *maximum_variable_size = EFI_VAR_BUF_SIZE -
395 sizeof(struct efi_var_file) -
396 sizeof(struct efi_var_entry);
397 return EFI_SUCCESS;
398 }
399
400 /**
401 * efi_query_variable_info_runtime() - runtime implementation of
402 * QueryVariableInfo()
403 *
404 * @attributes: bitmask to select variables to be
405 * queried
406 * @maximum_variable_storage_size: maximum size of storage area for the
407 * selected variable types
408 * @remaining_variable_storage_size: remaining size of storage are for the
409 * selected variable types
410 * @maximum_variable_size: maximum size of a variable of the
411 * selected type
412 * Returns: status code
413 */
efi_query_variable_info_runtime(u32 attributes,u64 * maximum_variable_storage_size,u64 * remaining_variable_storage_size,u64 * maximum_variable_size)414 static efi_status_t __efi_runtime EFIAPI efi_query_variable_info_runtime(
415 u32 attributes,
416 u64 *maximum_variable_storage_size,
417 u64 *remaining_variable_storage_size,
418 u64 *maximum_variable_size)
419 {
420 return EFI_UNSUPPORTED;
421 }
422
423 /**
424 * efi_set_variable_runtime() - runtime implementation of SetVariable()
425 *
426 * @variable_name: name of the variable
427 * @vendor: vendor GUID
428 * @attributes: attributes of the variable
429 * @data_size: size of the buffer with the variable value
430 * @data: buffer with the variable value
431 * Return: status code
432 */
433 static efi_status_t __efi_runtime EFIAPI
efi_set_variable_runtime(u16 * variable_name,const efi_guid_t * vendor,u32 attributes,efi_uintn_t data_size,const void * data)434 efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
435 u32 attributes, efi_uintn_t data_size,
436 const void *data)
437 {
438 return EFI_UNSUPPORTED;
439 }
440
441 /**
442 * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
443 */
efi_variables_boot_exit_notify(void)444 void efi_variables_boot_exit_notify(void)
445 {
446 /* Switch variable services functions to runtime version */
447 efi_runtime_services.get_variable = efi_get_variable_runtime;
448 efi_runtime_services.get_next_variable_name =
449 efi_get_next_variable_name_runtime;
450 efi_runtime_services.set_variable = efi_set_variable_runtime;
451 efi_runtime_services.query_variable_info =
452 efi_query_variable_info_runtime;
453 efi_update_table_header_crc32(&efi_runtime_services.hdr);
454 }
455
456 /**
457 * efi_init_variables() - initialize variable services
458 *
459 * Return: status code
460 */
efi_init_variables(void)461 efi_status_t efi_init_variables(void)
462 {
463 efi_status_t ret;
464
465 ret = efi_var_mem_init();
466 if (ret != EFI_SUCCESS)
467 return ret;
468
469 ret = efi_var_from_file();
470 if (ret != EFI_SUCCESS)
471 return ret;
472 if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
473 ret = efi_var_restore((struct efi_var_file *)
474 __efi_var_file_begin, true);
475 if (ret != EFI_SUCCESS)
476 log_err("Invalid EFI variable seed\n");
477 }
478
479
480 return efi_init_secure_state();
481 }
482