1 /* 2 * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 #include <assert.h> 8 #include <auth/auth_mod.h> 9 #include <platform.h> 10 #include <platform_oid.h> 11 #include <string.h> 12 13 /* 14 * Store a new non-volatile counter value. This implementation 15 * only allows updating of the platform's Trusted NV counter when a 16 * certificate protected by the Trusted NV counter is signed with 17 * the ROT key. This avoids a compromised secondary certificate from 18 * updating the platform's Trusted NV counter, which could lead to the 19 * platform becoming unusable. The function is suitable for all TBBR 20 * compliant platforms. 21 * 22 * Return: 0 = success, Otherwise = error 23 */ 24 int plat_set_nv_ctr2(void *cookie, const auth_img_desc_t *img_desc, 25 unsigned int nv_ctr) 26 { 27 int trusted_nv_ctr; 28 29 assert(cookie != NULL); 30 assert(img_desc != NULL); 31 32 trusted_nv_ctr = strcmp(cookie, TRUSTED_FW_NVCOUNTER_OID) == 0; 33 34 /* 35 * Only update the Trusted NV Counter if the certificate 36 * has been signed with the ROT key. Non Trusted NV counter 37 * updates are unconditional. 38 */ 39 if (!trusted_nv_ctr || img_desc->parent == NULL) 40 return plat_set_nv_ctr(cookie, nv_ctr); 41 42 /* 43 * Trusted certificates not signed with the ROT key are not 44 * allowed to update the Trusted NV Counter. 45 */ 46 return 1; 47 } 48