core: add fault mitigations to shdr_verify_signature*()

Adds fault mitigations to shdr_verify_signature() and shdr_verify_signature2(). shdr_verify_signature() and shdr_verify_signature2() are called using the wrapper FTMN_CALL_FUNC() which verifies that the correct function was called and that the return value hasn't been tampered with. Acked-by: Jerome Forissier <jerome.forissier@linaro.org> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
OP-TEE · Nov 25, 2022 · 8a69701 · 8a69701
1 parent b303be9
commit 8a69701
Showing 1 changed file with 48 additions and 26 deletions.
diff --git a/core/crypto/signed_hdr.c b/core/crypto/signed_hdr.c
@@ -4,6 +4,7 @@
  */
 
 #include <crypto/crypto.h>
+#include <fault_mitigation.h>
 #include <kernel/panic.h>
 #include <mempool.h>
 #include <signed_hdr.h>
@@ -59,46 +60,56 @@ TEE_Result shdr_verify_signature(const struct shdr *shdr)
 	struct rsa_public_key key = { };
 	TEE_Result res = TEE_SUCCESS;
 	uint32_t e = TEE_U32_TO_BIG_ENDIAN(ta_pub_key_exponent);
+	struct ftmn ftmn = { };
+	unsigned int err_incr = 2;
 	size_t hash_size = 0;
 	size_t hash_algo = 0;
 
 	if (shdr->magic != SHDR_MAGIC)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	if (TEE_ALG_GET_MAIN_ALG(shdr->algo) != TEE_MAIN_ALGO_RSA)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	hash_algo = TEE_DIGEST_HASH_TO_ALGO(shdr->algo);
 	if (is_weak_hash_algo(hash_algo))
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	res = tee_alg_get_digest_size(hash_algo, &hash_size);
 	if (res)
-		return TEE_ERROR_SECURITY;
+		goto err;
 	if (hash_size != shdr->hash_size)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	res = crypto_acipher_alloc_rsa_public_key(&key,
 						  ta_pub_key_modulus_size * 8);
 	if (res)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	res = crypto_bignum_bin2bn((uint8_t *)&e, sizeof(e), key.e);
 	if (res)
-		goto out;
+		goto err;
 	res = crypto_bignum_bin2bn(ta_pub_key_modulus, ta_pub_key_modulus_size,
 				   key.n);
 	if (res)
-		goto out;
+		goto err;
 
-	res = crypto_acipher_rsassa_verify(shdr->algo, &key, shdr->hash_size,
-					   SHDR_GET_HASH(shdr), shdr->hash_size,
-					   SHDR_GET_SIG(shdr), shdr->sig_size);
+	FTMN_CALL_FUNC(res, &ftmn, FTMN_INCR0,
+		       crypto_acipher_rsassa_verify, shdr->algo, &key,
+		       shdr->hash_size, SHDR_GET_HASH(shdr), shdr->hash_size,
+		       SHDR_GET_SIG(shdr), shdr->sig_size);
+	if (!res) {
+		ftmn_checkpoint(&ftmn, FTMN_INCR0);
+		goto out;
+	}
+	err_incr = 1;
+err:
+	res = TEE_ERROR_SECURITY;
+	FTMN_SET_CHECK_RES_NOT_ZERO(&ftmn, err_incr * FTMN_INCR0, res);
 out:
+	FTMN_CALLEE_DONE_CHECK(&ftmn, FTMN_INCR0, FTMN_STEP_COUNT(2), res);
 	crypto_acipher_free_rsa_public_key(&key);
-	if (res)
-		return TEE_ERROR_SECURITY;
-	return TEE_SUCCESS;
+	return res;
 }
 
 static const struct shdr_subkey_attr *
@@ -334,36 +345,47 @@ void shdr_free_pub_key(struct shdr_pub_key *key)
 TEE_Result shdr_verify_signature2(struct shdr_pub_key *key,
 				  const struct shdr *shdr)
 {
+	TEE_Result res = TEE_SUCCESS;
+	unsigned int err_incr = 2;
+	struct ftmn ftmn = { };
 	size_t hash_size = 0;
 	size_t hash_algo = 0;
 
 	if (shdr->magic != SHDR_MAGIC)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	if (TEE_ALG_GET_MAIN_ALG(shdr->algo) != key->main_algo)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	hash_algo = TEE_DIGEST_HASH_TO_ALGO(shdr->algo);
 	if (is_weak_hash_algo(hash_algo))
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	if (tee_alg_get_digest_size(hash_algo, &hash_size) ||
 	    hash_size != shdr->hash_size)
-		return TEE_ERROR_SECURITY;
+		goto err;
 
 	switch (key->main_algo) {
 	case TEE_MAIN_ALGO_RSA:
-		if (crypto_acipher_rsassa_verify(shdr->algo, key->pub_key.rsa,
-						 shdr->hash_size,
-						 SHDR_GET_HASH(shdr),
-						 shdr->hash_size,
-						 SHDR_GET_SIG(shdr),
-						 shdr->sig_size))
-			return TEE_ERROR_SECURITY;
+		FTMN_CALL_FUNC(res, &ftmn, FTMN_INCR0,
+			       crypto_acipher_rsassa_verify, shdr->algo,
+			       key->pub_key.rsa, shdr->hash_size,
+			       SHDR_GET_HASH(shdr), shdr->hash_size,
+			       SHDR_GET_SIG(shdr), shdr->sig_size);
 		break;
 	default:
 		panic();
 	}
 
-	return TEE_SUCCESS;
+	if (!res) {
+		ftmn_checkpoint(&ftmn, FTMN_INCR0);
+		goto out;
+	}
+	err_incr = 1;
+err:
+	res = TEE_ERROR_SECURITY;
+	FTMN_SET_CHECK_RES_NOT_ZERO(&ftmn, err_incr * FTMN_INCR0, res);
+out:
+	FTMN_CALLEE_DONE_CHECK(&ftmn, FTMN_INCR0, FTMN_STEP_COUNT(2), res);
+	return res;
 }