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-rw-r--r--drivers/auth/auth_mod.c458
1 files changed, 458 insertions, 0 deletions
diff --git a/drivers/auth/auth_mod.c b/drivers/auth/auth_mod.c
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+++ b/drivers/auth/auth_mod.c
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+/*
+ * Copyright (c) 2015-2022, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/debug.h>
+#include <common/tbbr/cot_def.h>
+#include <drivers/auth/auth_common.h>
+#include <drivers/auth/auth_mod.h>
+#include <drivers/auth/crypto_mod.h>
+#include <drivers/auth/img_parser_mod.h>
+#include <drivers/fwu/fwu.h>
+#include <lib/fconf/fconf_tbbr_getter.h>
+#include <plat/common/platform.h>
+
+/* 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, &param_ptr, &param_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;
+}