From 102b0d2daa97dae68d3eed54d8fe37a9cc38a892 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 11:13:47 +0200 Subject: Adding upstream version 2.8.0+dfsg. Signed-off-by: Daniel Baumann --- drivers/auth/auth_mod.c | 458 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 458 insertions(+) create mode 100644 drivers/auth/auth_mod.c (limited to 'drivers/auth/auth_mod.c') diff --git a/drivers/auth/auth_mod.c b/drivers/auth/auth_mod.c new file mode 100644 index 0000000..fa9509a --- /dev/null +++ b/drivers/auth/auth_mod.c @@ -0,0 +1,458 @@ +/* + * Copyright (c) 2015-2022, Arm Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include +#include +#include + +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* ASN.1 tags */ +#define ASN1_INTEGER 0x02 + +#define return_if_error(rc) \ + do { \ + if (rc != 0) { \ + return rc; \ + } \ + } while (0) + +#pragma weak plat_set_nv_ctr2 +#pragma weak plat_convert_pk + + +static int cmp_auth_param_type_desc(const auth_param_type_desc_t *a, + const auth_param_type_desc_t *b) +{ + if ((a->type == b->type) && (a->cookie == b->cookie)) { + return 0; + } + return 1; +} + +/* + * This function obtains the requested authentication parameter data from the + * information extracted from the parent image after its authentication. + */ +static int auth_get_param(const auth_param_type_desc_t *param_type_desc, + const auth_img_desc_t *img_desc, + void **param, unsigned int *len) +{ + int i; + + if (img_desc->authenticated_data == NULL) + return 1; + + for (i = 0 ; i < COT_MAX_VERIFIED_PARAMS ; i++) { + if (0 == cmp_auth_param_type_desc(param_type_desc, + img_desc->authenticated_data[i].type_desc)) { + *param = img_desc->authenticated_data[i].data.ptr; + *len = img_desc->authenticated_data[i].data.len; + return 0; + } + } + + return 1; +} + +/* + * Authenticate an image by matching the data hash + * + * This function implements 'AUTH_METHOD_HASH'. To authenticate an image using + * this method, the image must contain: + * + * - The data to calculate the hash from + * + * The parent image must contain: + * + * - The hash to be matched with (including hash algorithm) + * + * For a successful authentication, both hashes must match. The function calls + * the crypto-module to check this matching. + * + * Parameters: + * param: parameters to perform the hash authentication + * img_desc: pointer to image descriptor so we can know the image type + * and parent image + * img: pointer to image in memory + * img_len: length of image (in bytes) + * + * Return: + * 0 = success, Otherwise = error + */ +static int auth_hash(const auth_method_param_hash_t *param, + const auth_img_desc_t *img_desc, + void *img, unsigned int img_len) +{ + void *data_ptr, *hash_der_ptr; + unsigned int data_len, hash_der_len; + int rc = 0; + + /* Get the hash from the parent image. This hash will be DER encoded + * and contain the hash algorithm */ + rc = auth_get_param(param->hash, img_desc->parent, + &hash_der_ptr, &hash_der_len); + return_if_error(rc); + + /* Get the data to be hashed from the current image */ + rc = img_parser_get_auth_param(img_desc->img_type, param->data, + img, img_len, &data_ptr, &data_len); + return_if_error(rc); + + /* Ask the crypto module to verify this hash */ + rc = crypto_mod_verify_hash(data_ptr, data_len, + hash_der_ptr, hash_der_len); + + return rc; +} + +/* + * Authenticate by digital signature + * + * This function implements 'AUTH_METHOD_SIG'. To authenticate an image using + * this method, the image must contain: + * + * - Data to be signed + * - Signature + * - Signature algorithm + * + * We rely on the image parser module to extract this data from the image. + * The parent image must contain: + * + * - Public key (or a hash of it) + * + * If the parent image contains only a hash of the key, we will try to obtain + * the public key from the image itself (i.e. self-signed certificates). In that + * case, the signature verification is considered just an integrity check and + * the authentication is established by calculating the hash of the key and + * comparing it with the hash obtained from the parent. + * + * If the image has no parent (NULL), it means it has to be authenticated using + * the ROTPK stored in the platform. Again, this ROTPK could be the key itself + * or a hash of it. + * + * Return: 0 = success, Otherwise = error + */ +static int auth_signature(const auth_method_param_sig_t *param, + const auth_img_desc_t *img_desc, + void *img, unsigned int img_len) +{ + void *data_ptr, *pk_ptr, *pk_hash_ptr, *sig_ptr, *sig_alg_ptr; + unsigned int data_len, pk_len, pk_hash_len, sig_len, sig_alg_len; + unsigned int flags = 0; + int rc = 0; + + /* Get the data to be signed from current image */ + rc = img_parser_get_auth_param(img_desc->img_type, param->data, + img, img_len, &data_ptr, &data_len); + return_if_error(rc); + + /* Get the signature from current image */ + rc = img_parser_get_auth_param(img_desc->img_type, param->sig, + img, img_len, &sig_ptr, &sig_len); + return_if_error(rc); + + /* Get the signature algorithm from current image */ + rc = img_parser_get_auth_param(img_desc->img_type, param->alg, + img, img_len, &sig_alg_ptr, &sig_alg_len); + return_if_error(rc); + + /* Get the public key from the parent. If there is no parent (NULL), + * the certificate has been signed with the ROTPK, so we have to get + * the PK from the platform */ + if (img_desc->parent) { + rc = auth_get_param(param->pk, img_desc->parent, + &pk_ptr, &pk_len); + } else { + rc = plat_get_rotpk_info(param->pk->cookie, &pk_ptr, &pk_len, + &flags); + } + return_if_error(rc); + + if (flags & (ROTPK_IS_HASH | ROTPK_NOT_DEPLOYED)) { + /* If the PK is a hash of the key or if the ROTPK is not + deployed on the platform, retrieve the key from the image */ + pk_hash_ptr = pk_ptr; + pk_hash_len = pk_len; + rc = img_parser_get_auth_param(img_desc->img_type, + param->pk, img, img_len, + &pk_ptr, &pk_len); + return_if_error(rc); + + /* Ask the crypto module to verify the signature */ + rc = crypto_mod_verify_signature(data_ptr, data_len, + sig_ptr, sig_len, + sig_alg_ptr, sig_alg_len, + pk_ptr, pk_len); + return_if_error(rc); + + if (flags & ROTPK_NOT_DEPLOYED) { + NOTICE("ROTPK is not deployed on platform. " + "Skipping ROTPK verification.\n"); + } else { + /* platform may store the hash of a prefixed, suffixed or modified pk */ + rc = plat_convert_pk(pk_ptr, pk_len, &pk_ptr, &pk_len); + return_if_error(rc); + + /* Ask the crypto-module to verify the key hash */ + rc = crypto_mod_verify_hash(pk_ptr, pk_len, + pk_hash_ptr, pk_hash_len); + } + } else { + /* Ask the crypto module to verify the signature */ + rc = crypto_mod_verify_signature(data_ptr, data_len, + sig_ptr, sig_len, + sig_alg_ptr, sig_alg_len, + pk_ptr, pk_len); + } + + return rc; +} + +/* + * Authenticate by Non-Volatile counter + * + * To protect the system against rollback, the platform includes a non-volatile + * counter whose value can only be increased. All certificates include a counter + * value that should not be lower than the value stored in the platform. If the + * value is larger, the counter in the platform must be updated to the new value + * (provided it has been authenticated). + * + * Return: 0 = success, Otherwise = error + * Returns additionally, + * cert_nv_ctr -> NV counter value present in the certificate + * need_nv_ctr_upgrade = 0 -> platform NV counter upgrade is not needed + * need_nv_ctr_upgrade = 1 -> platform NV counter upgrade is needed + */ +static int auth_nvctr(const auth_method_param_nv_ctr_t *param, + const auth_img_desc_t *img_desc, + void *img, unsigned int img_len, + unsigned int *cert_nv_ctr, + bool *need_nv_ctr_upgrade) +{ + char *p; + void *data_ptr = NULL; + unsigned int data_len, len, i; + unsigned int plat_nv_ctr; + int rc = 0; + bool is_trial_run = false; + + /* Get the counter value from current image. The AM expects the IPM + * to return the counter value as a DER encoded integer */ + rc = img_parser_get_auth_param(img_desc->img_type, param->cert_nv_ctr, + img, img_len, &data_ptr, &data_len); + return_if_error(rc); + + /* Parse the DER encoded integer */ + assert(data_ptr); + p = (char *)data_ptr; + if (*p != ASN1_INTEGER) { + /* Invalid ASN.1 integer */ + return 1; + } + p++; + + /* NV-counters are unsigned integers up to 32-bit */ + len = (unsigned int)(*p & 0x7f); + if ((*p & 0x80) || (len > 4)) { + return 1; + } + p++; + + /* Check the number is not negative */ + if (*p & 0x80) { + return 1; + } + + /* Convert to unsigned int. This code is for a little-endian CPU */ + *cert_nv_ctr = 0; + for (i = 0; i < len; i++) { + *cert_nv_ctr = (*cert_nv_ctr << 8) | *p++; + } + + /* Get the counter from the platform */ + rc = plat_get_nv_ctr(param->plat_nv_ctr->cookie, &plat_nv_ctr); + return_if_error(rc); + + if (*cert_nv_ctr < plat_nv_ctr) { + /* Invalid NV-counter */ + return 1; + } else if (*cert_nv_ctr > plat_nv_ctr) { +#if PSA_FWU_SUPPORT && IMAGE_BL2 + is_trial_run = fwu_is_trial_run_state(); +#endif /* PSA_FWU_SUPPORT && IMAGE_BL2 */ + *need_nv_ctr_upgrade = !is_trial_run; + } + + return 0; +} + +int plat_set_nv_ctr2(void *cookie, const auth_img_desc_t *img_desc __unused, + unsigned int nv_ctr) +{ + return plat_set_nv_ctr(cookie, nv_ctr); +} + +int plat_convert_pk(void *full_pk_ptr, unsigned int full_pk_len, + void **hashed_pk_ptr, unsigned int *hashed_pk_len) +{ + *hashed_pk_ptr = full_pk_ptr; + *hashed_pk_len = full_pk_len; + + return 0; +} + +/* + * Return the parent id in the output parameter '*parent_id' + * + * Return value: + * 0 = Image has parent, 1 = Image has no parent or parent is authenticated + */ +int auth_mod_get_parent_id(unsigned int img_id, unsigned int *parent_id) +{ + const auth_img_desc_t *img_desc = NULL; + + assert(parent_id != NULL); + /* Get the image descriptor */ + img_desc = FCONF_GET_PROPERTY(tbbr, cot, img_id); + + /* Check if the image has no parent (ROT) */ + if (img_desc->parent == NULL) { + *parent_id = 0; + return 1; + } + + /* Check if the parent has already been authenticated */ + if (auth_img_flags[img_desc->parent->img_id] & IMG_FLAG_AUTHENTICATED) { + *parent_id = 0; + return 1; + } + + *parent_id = img_desc->parent->img_id; + return 0; +} + +/* + * Initialize the different modules in the authentication framework + */ +void auth_mod_init(void) +{ + /* Check we have a valid CoT registered */ + assert(cot_desc_ptr != NULL); + + /* Image parser module */ + img_parser_init(); +} + +/* + * Authenticate a certificate/image + * + * Return: 0 = success, Otherwise = error + */ +int auth_mod_verify_img(unsigned int img_id, + void *img_ptr, + unsigned int img_len) +{ + const auth_img_desc_t *img_desc = NULL; + const auth_method_desc_t *auth_method = NULL; + void *param_ptr; + unsigned int param_len; + int rc, i; + unsigned int cert_nv_ctr = 0; + bool need_nv_ctr_upgrade = false; + bool sig_auth_done = false; + const auth_method_param_nv_ctr_t *nv_ctr_param = NULL; + + /* Get the image descriptor from the chain of trust */ + img_desc = FCONF_GET_PROPERTY(tbbr, cot, img_id); + + /* Ask the parser to check the image integrity */ + rc = img_parser_check_integrity(img_desc->img_type, img_ptr, img_len); + return_if_error(rc); + + /* Authenticate the image using the methods indicated in the image + * descriptor. */ + if (img_desc->img_auth_methods == NULL) + return 1; + for (i = 0 ; i < AUTH_METHOD_NUM ; i++) { + auth_method = &img_desc->img_auth_methods[i]; + switch (auth_method->type) { + case AUTH_METHOD_NONE: + rc = 0; + break; + case AUTH_METHOD_HASH: + rc = auth_hash(&auth_method->param.hash, + img_desc, img_ptr, img_len); + break; + case AUTH_METHOD_SIG: + rc = auth_signature(&auth_method->param.sig, + img_desc, img_ptr, img_len); + sig_auth_done = true; + break; + case AUTH_METHOD_NV_CTR: + nv_ctr_param = &auth_method->param.nv_ctr; + rc = auth_nvctr(nv_ctr_param, + img_desc, img_ptr, img_len, + &cert_nv_ctr, &need_nv_ctr_upgrade); + break; + default: + /* Unknown authentication method */ + rc = 1; + break; + } + return_if_error(rc); + } + + /* + * Do platform NV counter upgrade only if the certificate gets + * authenticated, and platform NV-counter upgrade is needed. + */ + if (need_nv_ctr_upgrade && sig_auth_done) { + rc = plat_set_nv_ctr2(nv_ctr_param->plat_nv_ctr->cookie, + img_desc, cert_nv_ctr); + return_if_error(rc); + } + + /* Extract the parameters indicated in the image descriptor to + * authenticate the children images. */ + if (img_desc->authenticated_data != NULL) { + for (i = 0 ; i < COT_MAX_VERIFIED_PARAMS ; i++) { + if (img_desc->authenticated_data[i].type_desc == NULL) { + continue; + } + + /* Get the parameter from the image parser module */ + rc = img_parser_get_auth_param(img_desc->img_type, + img_desc->authenticated_data[i].type_desc, + img_ptr, img_len, ¶m_ptr, ¶m_len); + return_if_error(rc); + + /* Check parameter size */ + if (param_len > img_desc->authenticated_data[i].data.len) { + return 1; + } + + /* Copy the parameter for later use */ + memcpy((void *)img_desc->authenticated_data[i].data.ptr, + (void *)param_ptr, param_len); + } + } + + /* Mark image as authenticated */ + auth_img_flags[img_desc->img_id] |= IMG_FLAG_AUTHENTICATED; + + return 0; +} -- cgit v1.2.3