1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * purgatory: Runs between two kernels
4  *
5  * Copyright (C) 2014 Red Hat Inc.
6  *
7  * Author:
8  *       Vivek Goyal <vgoyal@redhat.com>
9  */
10 
11 #include <linux/bug.h>
12 #include <linux/kernel.h>
13 #include <linux/types.h>
14 #include <crypto/sha2.h>
15 #include <asm/purgatory.h>
16 
17 #include "../boot/string.h"
18 
19 u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
20 
21 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
22 
verify_sha256_digest(void)23 static int verify_sha256_digest(void)
24 {
25 	struct kexec_sha_region *ptr, *end;
26 	u8 digest[SHA256_DIGEST_SIZE];
27 	struct sha256_state sctx;
28 
29 	sha256_init(&sctx);
30 	end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
31 
32 	for (ptr = purgatory_sha_regions; ptr < end; ptr++)
33 		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
34 
35 	sha256_final(&sctx, digest);
36 
37 	if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
38 		return 1;
39 
40 	return 0;
41 }
42 
purgatory(void)43 void purgatory(void)
44 {
45 	int ret;
46 
47 	ret = verify_sha256_digest();
48 	if (ret) {
49 		/* loop forever */
50 		for (;;)
51 			;
52 	}
53 }
54 
55 /*
56  * Defined in order to reuse memcpy() and memset() from
57  * arch/x86/boot/compressed/string.c
58  */
warn(const char * msg)59 void warn(const char *msg) {}
60