Merge pull request #513 from LedgerHQ/fbe/further_reduce_stack

Further reduce stack usage

Author: fbeutin-ledger

Makefile

@@ -266,6 +266,9 @@ else
     APP_SOURCE_PATH += src_bagl
 endif
 
+# Allow usage of function from lib_standard_app/crypto_helpers.c
+APP_SOURCE_FILES += ${BOLOS_SDK}/lib_standard_app/crypto_helpers.c
+
 ### initialize plugin SDK submodule if needed, rebuild it, and warn if a difference is noticed
 ifeq ($(CHAIN),ethereum)
     ifneq ($(shell git submodule status | grep '^[-+]'),)

src_features/signTx/logic_signTx.c

@@ -319,13 +319,14 @@ static int strcasecmp_workaround(const char *str1, const char *str2) {
     return 0;
 }
 
-void finalizeParsing(bool direct) {
+__attribute__((noinline)) static void finalize_parsing_helper(bool direct, bool *use_standard_UI) {
     char displayBuffer[50];
     uint8_t decimals = WEI_TO_ETHER;
     uint64_t chain_id = get_tx_chain_id();
     const char *ticker = get_displayable_ticker(&chain_id);
     ethPluginFinalize_t pluginFinalize;
-    bool use_standard_UI = true;
+
+    *use_standard_UI = true;
 
     // Verify the chain
     if (chainConfig->chainId != ETHEREUM_MAINNET_CHAINID) {
@@ -396,7 +397,7 @@ void finalizeParsing(bool direct) {
             switch (pluginFinalize.uiType) {
                 case ETH_UI_TYPE_GENERIC:
                     // Use the dedicated ETH plugin UI
-                    use_standard_UI = false;
+                    *use_standard_UI = false;
                     tmpContent.txContent.dataPresent = false;
                     // Add the number of screens + the number of additional screens to get the total
                     // number of screens needed.
@@ -405,7 +406,7 @@ void finalizeParsing(bool direct) {
                     break;
                 case ETH_UI_TYPE_AMOUNT_ADDRESS:
                     // Use the standard ETH UI as this plugin uses the amount/address UI
-                    use_standard_UI = true;
+                    *use_standard_UI = true;
                     tmpContent.txContent.dataPresent = false;
                     if ((pluginFinalize.amount == NULL) || (pluginFinalize.address == NULL)) {
                         PRINTF("Incorrect amount/address set by plugin\n");
@@ -443,7 +444,7 @@ void finalizeParsing(bool direct) {
     }
 
     // User has just validated a swap but ETH received apdus about a non standard plugin / contract
-    if (G_called_from_swap && !use_standard_UI) {
+    if (G_called_from_swap && !*use_standard_UI) {
         PRINTF("ERR_SILENT_MODE_CHECK_FAILED, G_called_from_swap\n");
         THROW(ERR_SILENT_MODE_CHECK_FAILED);
     }
@@ -457,7 +458,7 @@ void finalizeParsing(bool direct) {
     }
 
     // Prepare destination address and amount to display
-    if (use_standard_UI) {
+    if (*use_standard_UI) {
         // Format the address in a temporary buffer, if in swap case compare it with validated
         // address, else commit it
         address_to_string(tmpContent.txContent.destination,
@@ -532,11 +533,14 @@ void finalizeParsing(bool direct) {
     // Prepare network field
     get_network_as_string(strings.common.network_name, sizeof(strings.common.network_name));
     PRINTF("Network: %s\n", strings.common.network_name);
+}
 
+void finalizeParsing(bool direct) {
+    bool use_standard_UI;
     bool no_consent_check;
-
-    // If called from swap, the user as already validated a standard transaction
-    // We have already checked the fields of this transaction above
+    finalize_parsing_helper(direct, &use_standard_UI);
+    // If called from swap, the user has already validated a standard transaction
+    // And we have already checked the fields of this transaction above
     no_consent_check = G_called_from_swap && use_standard_UI;
 
 #ifdef NO_CONSENT

src_features/signTx/ui_common_signTx.c

@@ -1,34 +1,26 @@
+#include "lib_standard_app/crypto_helpers.h"
 #include "os_io_seproxyhal.h"
 #include "shared_context.h"
 #include "utils.h"
 #include "common_ui.h"
 #include "handle_swap_sign_transaction.h"
 
 unsigned int io_seproxyhal_touch_tx_ok(__attribute__((unused)) const bagl_element_t *e) {
-    uint8_t privateKeyData[INT256_LENGTH];
-    uint8_t signature[100];
-    cx_ecfp_private_key_t privateKey;
-    uint32_t tx = 0;
+    uint32_t info = 0;
     int err;
-    io_seproxyhal_io_heartbeat();
-    os_perso_derive_node_bip32(CX_CURVE_256K1,
-                               tmpCtx.transactionContext.bip32.path,
-                               tmpCtx.transactionContext.bip32.length,
-                               privateKeyData,
-                               NULL);
-    cx_ecfp_init_private_key(CX_CURVE_256K1, privateKeyData, 32, &privateKey);
-    explicit_bzero(privateKeyData, sizeof(privateKeyData));
-    unsigned int info = 0;
-    io_seproxyhal_io_heartbeat();
-    cx_ecdsa_sign(&privateKey,
-                  CX_RND_RFC6979 | CX_LAST,
-                  CX_SHA256,
-                  tmpCtx.transactionContext.hash,
-                  sizeof(tmpCtx.transactionContext.hash),
-                  signature,
-                  sizeof(signature),
-                  &info);
-    explicit_bzero(&privateKey, sizeof(privateKey));
+    if (bip32_derive_ecdsa_sign_rs_hash_256(CX_CURVE_256K1,
+                                            tmpCtx.transactionContext.bip32.path,
+                                            tmpCtx.transactionContext.bip32.length,
+                                            CX_RND_RFC6979 | CX_LAST,
+                                            CX_SHA256,
+                                            tmpCtx.transactionContext.hash,
+                                            sizeof(tmpCtx.transactionContext.hash),
+                                            G_io_apdu_buffer + 1,
+                                            G_io_apdu_buffer + 1 + 32,
+                                            &info) != CX_OK) {
+        THROW(0x6F00);
+    }
+
     if (txContext.txType == EIP1559 || txContext.txType == EIP2930) {
         if (info & CX_ECCINFO_PARITY_ODD) {
             G_io_apdu_buffer[0] = 1;
@@ -57,13 +49,13 @@ unsigned int io_seproxyhal_touch_tx_ok(__attribute__((unused)) const bagl_elemen
             G_io_apdu_buffer[0] += 2;
         }
     }
-    format_signature_out(signature);
-    tx = 65;
-    G_io_apdu_buffer[tx++] = 0x90;
-    G_io_apdu_buffer[tx++] = 0x00;
+
+    // Write status code at parity_byte + r + s
+    G_io_apdu_buffer[1 + 64] = 0x90;
+    G_io_apdu_buffer[1 + 64 + 1] = 0x00;
 
     // Send back the response, do not restart the event loop
-    err = io_exchange(CHANNEL_APDU | IO_RETURN_AFTER_TX, tx);
+    err = io_exchange(CHANNEL_APDU | IO_RETURN_AFTER_TX, 1 + 64 + 2);
     if (G_called_from_swap) {
         PRINTF("G_called_from_swap\n");