1 files changed, 415 insertions, 0 deletions
diff --git a/drivers/auth/auth_mod.c b/drivers/auth/auth_mod.c
new file mode 100644
index 00000000..1cea60b2
--- /dev/null
+++ b/drivers/auth/auth_mod.c
@@ -0,0 +1,415 @@
+/*
+ * Copyright (c) 2015-2016, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <auth_common.h>
+#include <auth_mod.h>
+#include <cot_def.h>
+#include <crypto_mod.h>
+#include <debug.h>
+#include <img_parser_mod.h>
+#include <platform.h>
+#include <platform_def.h>
+#include <stdint.h>
+#include <string.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
+
+/* Pointer to CoT */
+extern const auth_img_desc_t *const cot_desc_ptr;
+extern unsigned int auth_img_flags[];
+
+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;
+
+	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 {
+			/* 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.
+ *
+ * Return: 0 = success, Otherwise = error
+ */
+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)
+{
+	char *p;
+	void *data_ptr = NULL;
+	unsigned int data_len, len, i;
+	unsigned int cert_nv_ctr, plat_nv_ctr;
+	int rc = 0;
+
+	/* 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) {
+		rc = plat_set_nv_ctr2(param->plat_nv_ctr->cookie,
+			img_desc, cert_nv_ctr);
+		return_if_error(rc);
+	}
+
+	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);
+}
+
+/*
+ * 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 = &cot_desc_ptr[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);
+
+	/* Crypto module */
+	crypto_mod_init();
+
+	/* 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;
+
+	/* Get the image descriptor from the chain of trust */
+	img_desc = &cot_desc_ptr[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. */
+	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);
+			break;
+		case AUTH_METHOD_NV_CTR:
+			rc = auth_nvctr(&auth_method->param.nv_ctr,
+					img_desc, img_ptr, img_len);
+			break;
+		default:
+			/* Unknown authentication method */
+			rc = 1;
+			break;
+		}
+		return_if_error(rc);
+	}
+
+	/* Extract the parameters indicated in the image descriptor to
+	 * authenticate the children images. */
+	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;
+}