libutils: remove buf_compare_ct()

Now that we have consttime_memcmp(), buf_compare_ct() is redundant.
Every time buf_compare_ct() is used, consttime_memcmp() may be used
instead.

This commit removes buf_compare_ct(). A compatibility wrapper is kept
in <string_ext.h> to avoid knowingly breaking the build of any TA that
may use it.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>

6 files changed, 10 insertions, 10 deletions

diff --git a/core/arch/arm/pta/secstor_ta_mgmt.c b/core/arch/arm/pta/secstor_ta_mgmt.c
index c3744a02..6ea093a5 100644
--- a/core/arch/arm/pta/secstor_ta_mgmt.c
+++ b/core/arch/arm/pta/secstor_ta_mgmt.c
@@ -121,7 +121,7 @@ static TEE_Result install_ta(struct shdr *shdr, const uint8_t *nw,
 	res = crypto_hash_final(hash_ctx, hash_algo, buf, shdr->hash_size);
 	if (res)
 		goto err_ta_finalize;
-	if (buf_compare_ct(buf, SHDR_GET_HASH(shdr), shdr->hash_size)) {
+	if (consttime_memcmp(buf, SHDR_GET_HASH(shdr), shdr->hash_size)) {
 		res = TEE_ERROR_SECURITY;
 		goto err_ta_finalize;
 	}
diff --git a/core/crypto/aes-gcm.c b/core/crypto/aes-gcm.c
index 464369c8..0cc1e99f 100644
--- a/core/crypto/aes-gcm.c
+++ b/core/crypto/aes-gcm.c
@@ -328,7 +328,7 @@ static TEE_Result __gcm_dec_final(struct internal_aes_gcm_state *state,
 	if (res)
 		return res;
 
-	if (buf_compare_ct(state->buf_tag, tag, tag_len))
+	if (consttime_memcmp(state->buf_tag, tag, tag_len))
 		return TEE_ERROR_MAC_INVALID;
 
 	return TEE_SUCCESS;
diff --git a/core/lib/libtomcrypt/include/tomcrypt_custom.h b/core/lib/libtomcrypt/include/tomcrypt_custom.h
index 1bb2f024..fef2035a 100644
--- a/core/lib/libtomcrypt/include/tomcrypt_custom.h
+++ b/core/lib/libtomcrypt/include/tomcrypt_custom.h
@@ -83,7 +83,7 @@
 #endif
 #ifndef XMEM_NEQ
 #include <string_ext.h>
-#define XMEM_NEQ  buf_compare_ct
+#define XMEM_NEQ consttime_memcmp
 #endif
 #ifndef XSTRCMP
    #ifdef strcmp
diff --git a/core/lib/libtomcrypt/src/tee_ltc_provider.c b/core/lib/libtomcrypt/src/tee_ltc_provider.c
index a679898c..8df13f80 100644
--- a/core/lib/libtomcrypt/src/tee_ltc_provider.c
+++ b/core/lib/libtomcrypt/src/tee_ltc_provider.c
@@ -2501,7 +2501,7 @@ TEE_Result crypto_aes_ccm_dec_final(void *ctx, const uint8_t *src_data,
 	if (ltc_res != CRYPT_OK)
 		return TEE_ERROR_BAD_STATE;
 
-	if (buf_compare_ct(dst_tag, tag, tag_len) != 0)
+	if (consttime_memcmp(dst_tag, tag, tag_len) != 0)
 		res = TEE_ERROR_MAC_INVALID;
 	else
 		res = TEE_SUCCESS;
@@ -2675,7 +2675,7 @@ TEE_Result crypto_aes_gcm_dec_final(void *ctx, const uint8_t *src_data,
 	if (ltc_res != CRYPT_OK)
 		return TEE_ERROR_BAD_STATE;
 
-	if (buf_compare_ct(dst_tag, tag, tag_len) != 0)
+	if (consttime_memcmp(dst_tag, tag, tag_len) != 0)
 		res = TEE_ERROR_MAC_INVALID;
 	else
 		res = TEE_SUCCESS;
@@ -2723,7 +2723,7 @@ TEE_Result hash_sha256_check(const uint8_t *hash, const uint8_t *data,
 		return TEE_ERROR_GENERIC;
 	if (sha256_done(&hs, digest) != CRYPT_OK)
 		return TEE_ERROR_GENERIC;
-	if (buf_compare_ct(digest, hash, sizeof(digest)) != 0)
+	if (consttime_memcmp(digest, hash, sizeof(digest)) != 0)
 		return TEE_ERROR_SECURITY;
 	return TEE_SUCCESS;
 }
diff --git a/core/tee/fs_htree.c b/core/tee/fs_htree.c
index 30f01ba8..8e817c28 100644
--- a/core/tee/fs_htree.c
+++ b/core/tee/fs_htree.c
@@ -577,7 +577,7 @@ static TEE_Result verify_node(struct traverse_arg *targ,
 	else
 		res = calc_node_hash(node, &targ->ht->imeta.meta, ctx, digest);
 	if (res == TEE_SUCCESS &&
-	    buf_compare_ct(digest, node->node.hash, sizeof(digest)))
+	    consttime_memcmp(digest, node->node.hash, sizeof(digest)))
 		return TEE_ERROR_CORRUPT_OBJECT;
 
 	return res;
diff --git a/core/tee/tee_rpmb_fs.c b/core/tee/tee_rpmb_fs.c
index 9fd397b9..0d123484 100644
--- a/core/tee/tee_rpmb_fs.c
+++ b/core/tee/tee_rpmb_fs.c
@@ -870,9 +870,9 @@ static TEE_Result tee_rpmb_resp_unpack_verify(struct rpmb_data_frame *datafrm,
 		}
 
 #ifndef CFG_RPMB_FS_NO_MAC
-		if (buf_compare_ct(rawdata->key_mac,
-				   (datafrm + nbr_frms - 1)->key_mac,
-				   RPMB_KEY_MAC_SIZE) != 0) {
+		if (consttime_memcmp(rawdata->key_mac,
+				     (datafrm + nbr_frms - 1)->key_mac,
+				     RPMB_KEY_MAC_SIZE) != 0) {
 			DMSG("MAC mismatched:");
 #ifdef CFG_RPMB_FS_DEBUG_DATA
 			DHEXDUMP((uint8_t *)rawdata->key_mac, 32);