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/compressed/error.h"
18 #include "../boot/string.h"
19 
20 u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
21 
22 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
23 
verify_sha256_digest(void)24 static int verify_sha256_digest(void)
25 {
26 	struct kexec_sha_region *ptr, *end;
27 	u8 digest[SHA256_DIGEST_SIZE];
28 	struct sha256_state sctx;
29 
30 	sha256_init(&sctx);
31 	end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
32 
33 	for (ptr = purgatory_sha_regions; ptr < end; ptr++)
34 		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
35 
36 	sha256_final(&sctx, digest);
37 
38 	if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
39 		return 1;
40 
41 	return 0;
42 }
43 
purgatory(void)44 void purgatory(void)
45 {
46 	int ret;
47 
48 	ret = verify_sha256_digest();
49 	if (ret) {
50 		/* loop forever */
51 		for (;;)
52 			;
53 	}
54 }
55 
56 /*
57  * Defined in order to reuse memcpy() and memset() from
58  * arch/x86/boot/compressed/string.c
59  */
warn(const char * msg)60 void warn(const char *msg) {}
61