1 /* 2 * Copyright (c) 2016-2017, 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 #if USE_TBBR_DEFS 11 #include <tbbr_oid.h> 12 #else 13 #include <platform_oid.h> 14 #endif 15 #include <string.h> 16 17 /* 18 * Store a new non-volatile counter value. This implementation 19 * only allows updating of the platform's Trusted NV counter when a 20 * certificate protected by the Trusted NV counter is signed with 21 * the ROT key. This avoids a compromised secondary certificate from 22 * updating the platform's Trusted NV counter, which could lead to the 23 * platform becoming unusable. The function is suitable for all TBBR 24 * compliant platforms. 25 * 26 * Return: 0 = success, Otherwise = error 27 */ 28 int plat_set_nv_ctr2(void *cookie, const auth_img_desc_t *img_desc, 29 unsigned int nv_ctr) 30 { 31 int trusted_nv_ctr; 32 33 assert(cookie != NULL); 34 assert(img_desc != NULL); 35 36 trusted_nv_ctr = strcmp(cookie, TRUSTED_FW_NVCOUNTER_OID) == 0; 37 38 /* 39 * Only update the Trusted NV Counter if the certificate 40 * has been signed with the ROT key. Non Trusted NV counter 41 * updates are unconditional. 42 */ 43 if (!trusted_nv_ctr || img_desc->parent == NULL) 44 return plat_set_nv_ctr(cookie, nv_ctr); 45 46 /* 47 * Trusted certificates not signed with the ROT key are not 48 * allowed to update the Trusted NV Counter. 49 */ 50 return 1; 51 } 52
