1 /* 2 * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are met: 6 * 7 * Redistributions of source code must retain the above copyright notice, this 8 * list of conditions and the following disclaimer. 9 * 10 * Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 14 * Neither the name of ARM nor the names of its contributors may be used 15 * to endorse or promote products derived from this software without specific 16 * prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <assert.h> 32 #include <auth/auth_mod.h> 33 #include <platform.h> 34 #include <platform_oid.h> 35 #include <string.h> 36 37 /* 38 * Store a new non-volatile counter value. This implementation 39 * only allows updating of the platform's Trusted NV counter when a 40 * certificate protected by the Trusted NV counter is signed with 41 * the ROT key. This avoids a compromised secondary certificate from 42 * updating the platform's Trusted NV counter, which could lead to the 43 * platform becoming unusable. The function is suitable for all TBBR 44 * compliant platforms. 45 * 46 * Return: 0 = success, Otherwise = error 47 */ 48 int plat_set_nv_ctr2(void *cookie, const auth_img_desc_t *img_desc, 49 unsigned int nv_ctr) 50 { 51 int trusted_nv_ctr; 52 53 assert(cookie != NULL); 54 assert(img_desc != NULL); 55 56 trusted_nv_ctr = strcmp(cookie, TRUSTED_FW_NVCOUNTER_OID) == 0; 57 58 /* 59 * Only update the Trusted NV Counter if the certificate 60 * has been signed with the ROT key. Non Trusted NV counter 61 * updates are unconditional. 62 */ 63 if (!trusted_nv_ctr || img_desc->parent == NULL) 64 return plat_set_nv_ctr(cookie, nv_ctr); 65 66 /* 67 * Trusted certificates not signed with the ROT key are not 68 * allowed to update the Trusted NV Counter. 69 */ 70 return 1; 71 } 72