s390/purgatory/purgatory.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Purgatory code running between two kernels.
0004  *
0005  * Copyright IBM Corp. 2018
0006  *
0007  * Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com>
0008  */
0009
0010 #include <linux/kexec.h>
0011 #include <linux/string.h>
0012 #include <crypto/sha2.h>
0013 #include <asm/purgatory.h>
0014
0015 int verify_sha256_digest(void)
0016 {
0017     struct kexec_sha_region *ptr, *end;
0018     u8 digest[SHA256_DIGEST_SIZE];
0019     struct sha256_state sctx;
0020
0021     sha256_init(&sctx);
0022     end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
0023
0024     for (ptr = purgatory_sha_regions; ptr < end; ptr++)
0025         sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
0026
0027     sha256_final(&sctx, digest);
0028
0029     if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
0030         return 1;
0031
0032     return 0;
0033 }