summaryrefslogtreecommitdiff
path: root/src/security/vboot/vboot_logic.c
blob: 2fc20fabd47e5c2993a3ff8b3003208fefbf9e00 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
/*
 * This file is part of the coreboot project.
 *
 * Copyright 2014 Google Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <arch/exception.h>
#include <assert.h>
#include <bootmode.h>
#include <console/console.h>
#include <console/vtxprintf.h>
#include <delay.h>
#include <string.h>
#include <timestamp.h>
#include <vb2_api.h>
#include <security/vboot/misc.h>
#include <security/vboot/vbnv.h>

#include "antirollback.h"

/* The max hash size to expect is for SHA512. */
#define VBOOT_MAX_HASH_SIZE VB2_SHA512_DIGEST_SIZE

#define TODO_BLOCK_SIZE 1024

static int is_slot_a(struct vb2_context *ctx)
{
	return !(ctx->flags & VB2_CONTEXT_FW_SLOT_B);
}

/* exports */

void vb2ex_printf(const char *func, const char *fmt, ...)
{
	va_list args;

	if (func)
		printk(BIOS_INFO, "VB2:%s() ", func);

	va_start(args, fmt);
	do_printk_va_list(BIOS_INFO, fmt, args);
	va_end(args);

	return;
}

int vb2ex_read_resource(struct vb2_context *ctx,
			enum vb2_resource_index index,
			uint32_t offset,
			void *buf,
			uint32_t size)
{
	struct region_device rdev;
	const char *name;

	switch (index) {
	case VB2_RES_GBB:
		name = "GBB";
		break;
	case VB2_RES_FW_VBLOCK:
		if (is_slot_a(ctx))
			name = "VBLOCK_A";
		else
			name = "VBLOCK_B";
		break;
	default:
		return VB2_ERROR_EX_READ_RESOURCE_INDEX;
	}

	if (vboot_named_region_device(name, &rdev))
		return VB2_ERROR_EX_READ_RESOURCE_SIZE;

	if (rdev_readat(&rdev, buf, offset, size) != size)
		return VB2_ERROR_EX_READ_RESOURCE_SIZE;

	return VB2_SUCCESS;
}

/* No-op stubs that can be overridden by SoCs with hardware crypto support. */
__weak
int vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
			       uint32_t data_size)
{
	return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
}

__weak
int vb2ex_hwcrypto_digest_extend(const uint8_t *buf, uint32_t size)
{
	BUG();	/* Should never get called if init() returned an error. */
	return VB2_ERROR_UNKNOWN;
}

__weak
int vb2ex_hwcrypto_digest_finalize(uint8_t *digest, uint32_t digest_size)
{
	BUG();	/* Should never get called if init() returned an error. */
	return VB2_ERROR_UNKNOWN;
}

static int handle_digest_result(void *slot_hash, size_t slot_hash_sz)
{
	int is_resume;

	/*
	 * Chrome EC is the only support for vboot_save_hash() &
	 * vboot_retrieve_hash(), if Chrome EC is not enabled then return.
	 */
	if (!IS_ENABLED(CONFIG_EC_GOOGLE_CHROMEEC))
		return 0;

	/*
	 * Nothing to do since resuming on the platform doesn't require
	 * vboot verification again.
	 */
	if (!IS_ENABLED(CONFIG_RESUME_PATH_SAME_AS_BOOT))
		return 0;

	/*
	 * Assume that if vboot doesn't start in bootblock verified
	 * RW memory init code is not employed. i.e. memory init code
	 * lives in RO CBFS.
	 */
	if (!IS_ENABLED(CONFIG_VBOOT_STARTS_IN_BOOTBLOCK))
		return 0;

	is_resume = vboot_platform_is_resuming();

	if (is_resume > 0) {
		uint8_t saved_hash[VBOOT_MAX_HASH_SIZE];
		const size_t saved_hash_sz = sizeof(saved_hash);

		assert(slot_hash_sz == saved_hash_sz);

		printk(BIOS_DEBUG, "Platform is resuming.\n");

		if (vboot_retrieve_hash(saved_hash, saved_hash_sz)) {
			printk(BIOS_ERR, "Couldn't retrieve saved hash.\n");
			return -1;
		}

		if (memcmp(saved_hash, slot_hash, slot_hash_sz)) {
			printk(BIOS_ERR, "Hash mismatch on resume.\n");
			return -1;
		}
	} else if (is_resume < 0)
		printk(BIOS_ERR, "Unable to determine if platform resuming.\n");

	printk(BIOS_DEBUG, "Saving vboot hash.\n");

	/* Always save the hash for the current boot. */
	if (vboot_save_hash(slot_hash, slot_hash_sz)) {
		printk(BIOS_ERR, "Error saving vboot hash.\n");
		/* Though this is an error don't report it up since it could
		 * lead to a reboot loop. The consequence of this is that
		 * we will most likely fail resuming because of EC issues or
		 * the hash digest not matching. */
		return 0;
	}

	return 0;
}

static int hash_body(struct vb2_context *ctx, struct region_device *fw_main)
{
	uint64_t load_ts;
	uint32_t expected_size;
	uint8_t block[TODO_BLOCK_SIZE];
	uint8_t hash_digest[VBOOT_MAX_HASH_SIZE];
	const size_t hash_digest_sz = sizeof(hash_digest);
	size_t block_size = sizeof(block);
	size_t offset;
	int rv;

	/* Clear the full digest so that any hash digests less than the
	 * max have trailing zeros. */
	memset(hash_digest, 0, hash_digest_sz);

	/*
	 * Since loading the firmware and calculating its hash is intertwined,
	 * we use this little trick to measure them separately and pretend it
	 * was first loaded and then hashed in one piece with the timestamps.
	 * (This split won't make sense with memory-mapped media like on x86.)
	 */
	load_ts = timestamp_get();
	timestamp_add(TS_START_HASH_BODY, load_ts);

	expected_size = region_device_sz(fw_main);
	offset = 0;

	/* Start the body hash */
	rv = vb2api_init_hash(ctx, VB2_HASH_TAG_FW_BODY, &expected_size);
	if (rv)
		return rv;

	/*
	 * Honor vboot's RW slot size. The expected size is pulled out of
	 * the preamble and obtained through vb2api_init_hash() above. By
	 * creating sub region the RW slot portion of the boot media is
	 * limited.
	 */
	if (rdev_chain(fw_main, fw_main, 0, expected_size)) {
		printk(BIOS_ERR, "Unable to restrict CBFS size.\n");
		return VB2_ERROR_UNKNOWN;
	}

	/* Extend over the body */
	while (expected_size) {
		uint64_t temp_ts;
		if (block_size > expected_size)
			block_size = expected_size;

		temp_ts = timestamp_get();
		if (rdev_readat(fw_main, block, offset, block_size) < 0)
			return VB2_ERROR_UNKNOWN;
		load_ts += timestamp_get() - temp_ts;

		rv = vb2api_extend_hash(ctx, block, block_size);
		if (rv)
			return rv;

		expected_size -= block_size;
		offset += block_size;
	}

	timestamp_add(TS_DONE_LOADING, load_ts);
	timestamp_add_now(TS_DONE_HASHING);

	/* Check the result (with RSA signature verification) */
	rv = vb2api_check_hash_get_digest(ctx, hash_digest, hash_digest_sz);
	if (rv)
		return rv;

	timestamp_add_now(TS_END_HASH_BODY);

	if (handle_digest_result(hash_digest, hash_digest_sz))
		return VB2_ERROR_UNKNOWN;

	return VB2_SUCCESS;
}

static int locate_firmware(struct vb2_context *ctx,
				struct region_device *fw_main)
{
	const char *name;

	if (is_slot_a(ctx))
		name = "FW_MAIN_A";
	else
		name = "FW_MAIN_B";

	return vboot_named_region_device(name, fw_main);
}

/**
 * Save non-volatile and/or secure data if needed.
 */
static void save_if_needed(struct vb2_context *ctx)
{
	if (ctx->flags & VB2_CONTEXT_NVDATA_CHANGED) {
		printk(BIOS_INFO, "Saving nvdata\n");
		save_vbnv(ctx->nvdata);
		ctx->flags &= ~VB2_CONTEXT_NVDATA_CHANGED;
	}
	if (ctx->flags & VB2_CONTEXT_SECDATA_CHANGED) {
		printk(BIOS_INFO, "Saving secdata\n");
		antirollback_write_space_firmware(ctx);
		ctx->flags &= ~VB2_CONTEXT_SECDATA_CHANGED;
	}
}

static uint32_t extend_pcrs(struct vb2_context *ctx)
{
	return vboot_extend_pcr(ctx, 0, BOOT_MODE_PCR) ||
	       vboot_extend_pcr(ctx, 1, HWID_DIGEST_PCR);
}

/**
 * Verify and select the firmware in the RW image
 *
 * TODO: Avoid loading a stage twice (once in hash_body & again in load_stage).
 * when per-stage verification is ready.
 */
void verstage_main(void)
{
	struct vb2_context ctx;
	struct region_device fw_main;
	int rv;

	timestamp_add_now(TS_START_VBOOT);

	/* Set up context and work buffer */
	vb2_init_work_context(&ctx);

	/* Initialize and read nvdata from non-volatile storage. */
	vbnv_init(ctx.nvdata);

	/* Set S3 resume flag if vboot should behave differently when selecting
	 * which slot to boot.  This is only relevant to vboot if the platform
	 * does verification of memory init and thus must ensure it resumes with
	 * the same slot that it booted from. */
	if (IS_ENABLED(CONFIG_RESUME_PATH_SAME_AS_BOOT) &&
	    IS_ENABLED(CONFIG_VBOOT_STARTS_IN_BOOTBLOCK) &&
	    vboot_platform_is_resuming())
		ctx.flags |= VB2_CONTEXT_S3_RESUME;

	/* Read secdata from TPM. Initialize TPM if secdata not found. We don't
	 * check the return value here because vb2api_fw_phase1 will catch
	 * invalid secdata and tell us what to do (=reboot). */
	timestamp_add_now(TS_START_TPMINIT);
	antirollback_read_space_firmware(&ctx);
	timestamp_add_now(TS_END_TPMINIT);

	if (IS_ENABLED(CONFIG_VBOOT_PHYSICAL_DEV_SWITCH) &&
	    get_developer_mode_switch())
		ctx.flags |= VB2_CONTEXT_FORCE_DEVELOPER_MODE;

	if (get_recovery_mode_switch()) {
		ctx.flags |= VB2_CONTEXT_FORCE_RECOVERY_MODE;
		if (IS_ENABLED(CONFIG_VBOOT_DISABLE_DEV_ON_RECOVERY))
			ctx.flags |= VB2_DISABLE_DEVELOPER_MODE;
	}

	if (IS_ENABLED(CONFIG_VBOOT_WIPEOUT_SUPPORTED) &&
	    get_wipeout_mode_switch())
		ctx.flags |= VB2_CONTEXT_FORCE_WIPEOUT_MODE;

	if (IS_ENABLED(CONFIG_VBOOT_LID_SWITCH) && !get_lid_switch())
		ctx.flags |= VB2_CONTEXT_NOFAIL_BOOT;

	/* Do early init (set up secdata and NVRAM, load GBB) */
	printk(BIOS_INFO, "Phase 1\n");
	rv = vb2api_fw_phase1(&ctx);

	if (rv) {
		/*
		 * If vb2api_fw_phase1 fails, check for return value.
		 * If it is set to VB2_ERROR_API_PHASE1_RECOVERY, then continue
		 * into recovery mode.
		 * For any other error code, save context if needed and reboot.
		 */
		if (rv == VB2_ERROR_API_PHASE1_RECOVERY) {
			printk(BIOS_INFO, "Recovery requested (%x)\n", rv);
			save_if_needed(&ctx);
			extend_pcrs(&ctx);	/* ignore failures */
			timestamp_add_now(TS_END_VBOOT);
			return;
		}

		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
		save_if_needed(&ctx);
		vboot_reboot();
	}

	/* Determine which firmware slot to boot (based on NVRAM) */
	printk(BIOS_INFO, "Phase 2\n");
	rv = vb2api_fw_phase2(&ctx);
	if (rv) {
		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
		save_if_needed(&ctx);
		vboot_reboot();
	}

	/* Try that slot (verify its keyblock and preamble) */
	printk(BIOS_INFO, "Phase 3\n");
	timestamp_add_now(TS_START_VERIFY_SLOT);
	rv = vb2api_fw_phase3(&ctx);
	timestamp_add_now(TS_END_VERIFY_SLOT);
	if (rv) {
		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
		save_if_needed(&ctx);
		vboot_reboot();
	}

	printk(BIOS_INFO, "Phase 4\n");
	rv = locate_firmware(&ctx, &fw_main);
	if (rv)
		die("Failed to read FMAP to locate firmware");

	rv = hash_body(&ctx, &fw_main);
	save_if_needed(&ctx);
	if (rv) {
		printk(BIOS_INFO, "Reboot requested (%x)\n", rv);
		vboot_reboot();
	}

	timestamp_add_now(TS_START_TPMPCR);
	rv = extend_pcrs(&ctx);
	if (rv) {
		printk(BIOS_WARNING, "Failed to extend TPM PCRs (%#x)\n", rv);
		vb2api_fail(&ctx, VB2_RECOVERY_RO_TPM_U_ERROR, rv);
		save_if_needed(&ctx);
		vboot_reboot();
	}
	timestamp_add_now(TS_END_TPMPCR);

	/* Lock TPM */

	timestamp_add_now(TS_START_TPMLOCK);
	rv = antirollback_lock_space_firmware();
	if (rv) {
		printk(BIOS_INFO, "Failed to lock TPM (%x)\n", rv);
		vb2api_fail(&ctx, VB2_RECOVERY_RO_TPM_L_ERROR, 0);
		save_if_needed(&ctx);
		vboot_reboot();
	}
	timestamp_add_now(TS_END_TPMLOCK);

	/* Lock rec hash space if available. */
	if (IS_ENABLED(CONFIG_VBOOT_HAS_REC_HASH_SPACE)) {
		rv = antirollback_lock_space_rec_hash();
		if (rv) {
			printk(BIOS_INFO, "Failed to lock rec hash space(%x)\n",
			       rv);
			vb2api_fail(&ctx, VB2_RECOVERY_RO_TPM_REC_HASH_L_ERROR,
				    0);
			save_if_needed(&ctx);
			vboot_reboot();
		}
	}

	printk(BIOS_INFO, "Slot %c is selected\n", is_slot_a(&ctx) ? 'A' : 'B');
	vb2_set_selected_region(region_device_region(&fw_main));
	timestamp_add_now(TS_END_VBOOT);
}