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feat(legacy): Strict path validation for Ethereum.

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release/22.05
Andrew Kozlik 2 years ago committed by Martin Milata
parent 054ab48689
commit 0af5cd18c2
5 changed files with 143 additions and 5 deletions
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1
legacy/firmware/.changelog.d/noissue.security
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@ -0,0 +1 @@
Strict path validations for altcoins.

49
legacy/firmware/ethereum.c
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@ -1040,3 +1040,52 @@ bool ethereum_parse(const char *address, uint8_t pubkeyhash[20]) {
}
return true;
}
bool ethereum_path_check(uint32_t address_n_count, const uint32_t *address_n,
bool pubkey_export, uint64_t chain) {
bool valid = (address_n_count >= 3);
valid = valid && (address_n[0] == (PATH_HARDENED | 44));
valid = valid && (address_n[1] & PATH_HARDENED);
valid = valid && (address_n[2] & PATH_HARDENED);
valid = valid && ((address_n[2] & PATH_UNHARDEN_MASK) <= PATH_MAX_ACCOUNT);
uint32_t path_slip44 = address_n[1] & PATH_UNHARDEN_MASK;
if (chain == CHAIN_ID_UNKNOWN) {
valid = valid && (is_ethereum_slip44(path_slip44));
} else {
uint32_t chain_slip44 = ethereum_slip44_by_chain_id(chain);
if (chain_slip44 == SLIP44_UNKNOWN) {
// Allow Ethereum or testnet paths for unknown networks.
valid = valid && (path_slip44 == 60 || path_slip44 == 1);
} else if (chain_slip44 != 60 && chain_slip44 != 1) {
// Allow cross-signing with Ethereum unless it's testnet.
valid = valid && (path_slip44 == chain_slip44 || path_slip44 == 60);
} else {
valid = valid && (path_slip44 == chain_slip44);
}
}
if (pubkey_export) {
// m/44'/coin_type'/account'/*
return valid;
}
if (address_n_count == 3) {
// SEP-0005 for non-UTXO-based currencies, defined by Stellar:
// https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0005.md
// m/44'/coin_type'/account'
return valid;
}
// We believe Ethereum should use the SEP-0005 scheme for everything, because
// it is account-based, rather than UTXO-based. Unfortunately, a lot of
// Ethereum tools (MEW, Metamask) do not use such scheme and set account = 0
// and then iterate the address index. For compatibility, we allow this scheme
// as well.
// m/44'/coin_type'/account'/change/address_index
valid = valid && (address_n_count == 5);
valid = valid && (address_n[3] <= PATH_MAX_CHANGE);
valid = valid && (address_n[4] <= PATH_MAX_ADDRESS_INDEX);
return valid;
}

4
legacy/firmware/ethereum.h
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@ -25,6 +25,8 @@
#include "bip32.h"
#include "messages-ethereum.pb.h"
#define CHAIN_ID_UNKNOWN UINT64_MAX
void ethereum_signing_init(const EthereumSignTx *msg, const HDNode *node);
void ethereum_signing_init_eip1559(const EthereumSignTxEIP1559 *msg,
const HDNode *node);
@ -39,4 +41,6 @@ void ethereum_typed_hash_sign(const EthereumSignTypedHash *msg,
EthereumTypedDataSignature *resp);
bool ethereum_parse(const char *address, uint8_t pubkeyhash[20]);
bool ethereum_path_check(uint32_t address_n_count, const uint32_t *address_n,
bool pubkey_export, uint64_t chain);
#endif

35
legacy/firmware/ethereum_networks.h.mako
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@ -3,14 +3,19 @@ BKSL = "\\"
networks = list(supported_on("trezor1", eth))
max_chain_id_length = 0
max_slip44_length = 0
max_suffix_length = 0
for n in networks:
max_chain_id_length = max(len(str(n.chain_id)), max_chain_id_length)
max_slip44_length = max(len(str(n.slip44)), max_slip44_length)
max_suffix_length = max(len(n.shortcut), max_suffix_length)
def align_chain_id(n):
return "{:>{w}}".format(n.chain_id, w=max_chain_id_length)
def align_slip44(n):
return "{:>{w}}".format(n.slip44, w=max_slip44_length)
def align_suffix(n):
cstr = c_str(" " + n.shortcut) + ";"
# we add two quotes, a space and a semicolon. hence +4 chars
@ -23,12 +28,34 @@ def align_suffix(n):
#ifndef __ETHEREUM_NETWORKS_H__
#define __ETHEREUM_NETWORKS_H__
#define SLIP44_UNKNOWN UINT32_MAX
#define ASSIGN_ETHEREUM_SUFFIX(suffix, chain_id) ${BKSL}
switch (chain_id) { ${BKSL}
switch (chain_id) { ${BKSL}
% for n in networks:
case ${align_chain_id(n)}: suffix = ${align_suffix(n)} break; /* ${n.name} */ ${BKSL}
% endfor
default: suffix = " UNKN"; break; /* unknown chain */ ${BKSL}
}
static bool is_ethereum_slip44(uint32_t slip44) {
switch (slip44) {
% for slip44 in sorted(set(n.slip44 for n in networks)):
case ${slip44}:
% endfor
return true;
default:
return false;
}
}
static int32_t ethereum_slip44_by_chain_id(uint64_t chain_id) {
switch (chain_id) {
% for n in networks:
case ${align_chain_id(n)}: suffix = ${align_suffix(n)} break; /* ${n.name} */ ${BKSL}
case ${align_chain_id(n)}: return ${align_slip44(n)}; /* ${n.name} */
% endfor
default: suffix = " UNKN"; break; /* unknown chain */ ${BKSL}
}
default: return SLIP44_UNKNOWN; /* unknown chain */
}
}
#endif

59
legacy/firmware/fsm_msg_ethereum.h
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@ -17,6 +17,22 @@
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
static bool fsm_ethereumCheckPath(uint32_t address_n_count,
const uint32_t *address_n, bool pubkey_export,
uint64_t chain_id) {
if (ethereum_path_check(address_n_count, address_n, pubkey_export,
chain_id)) {
return true;
}
if (config_getSafetyCheckLevel() == SafetyCheckLevel_Strict) {
fsm_sendFailure(FailureType_Failure_DataError, _("Forbidden key path"));
return false;
}
return fsm_layoutPathWarning();
}
void fsm_msgEthereumGetPublicKey(const EthereumGetPublicKey *msg) {
RESP_INIT(EthereumPublicKey);
@ -28,6 +44,12 @@ void fsm_msgEthereumGetPublicKey(const EthereumGetPublicKey *msg) {
const CoinInfo *coin = fsm_getCoin(true, "Bitcoin");
if (!coin) return;
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, true,
CHAIN_ID_UNKNOWN)) {
layoutHome();
return;
}
const char *curve = coin->curve_name;
uint32_t fingerprint;
HDNode *node = fsm_getDerivedNode(curve, msg->address_n, msg->address_n_count,
@ -71,6 +93,12 @@ void fsm_msgEthereumSignTx(const EthereumSignTx *msg) {
CHECK_PIN
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
msg->chain_id)) {
layoutHome();
return;
}
const HDNode *node = fsm_getDerivedNode(SECP256K1_NAME, msg->address_n,
msg->address_n_count, NULL);
if (!node) return;
@ -83,6 +111,12 @@ void fsm_msgEthereumSignTxEIP1559(const EthereumSignTxEIP1559 *msg) {
CHECK_PIN
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
msg->chain_id)) {
layoutHome();
return;
}
const HDNode *node = fsm_getDerivedNode(SECP256K1_NAME, msg->address_n,
msg->address_n_count, NULL);
if (!node) return;
@ -101,13 +135,22 @@ void fsm_msgEthereumGetAddress(const EthereumGetAddress *msg) {
CHECK_PIN
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
CHAIN_ID_UNKNOWN)) {
layoutHome();
return;
}
const HDNode *node = fsm_getDerivedNode(SECP256K1_NAME, msg->address_n,
msg->address_n_count, NULL);
if (!node) return;
uint8_t pubkeyhash[20];
if (!hdnode_get_ethereum_pubkeyhash(node, pubkeyhash)) return;
if (!hdnode_get_ethereum_pubkeyhash(node, pubkeyhash)) {
layoutHome();
return;
}
uint32_t slip44 =
(msg->address_n_count > 1) ? (msg->address_n[1] & PATH_UNHARDEN_MASK) : 0;
@ -150,12 +193,19 @@ void fsm_msgEthereumSignMessage(const EthereumSignMessage *msg) {
CHECK_PIN
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
CHAIN_ID_UNKNOWN)) {
layoutHome();
return;
}
const HDNode *node = fsm_getDerivedNode(SECP256K1_NAME, msg->address_n,
msg->address_n_count, NULL);
if (!node) return;
uint8_t pubkeyhash[20] = {0};
if (!hdnode_get_ethereum_pubkeyhash(node, pubkeyhash)) {
layoutHome();
return;
}
@ -230,6 +280,12 @@ void fsm_msgEthereumSignTypedHash(const EthereumSignTypedHash *msg) {
return;
}
if (!fsm_ethereumCheckPath(msg->address_n_count, msg->address_n, false,
CHAIN_ID_UNKNOWN)) {
layoutHome();
return;
}
layoutDialogSwipe(&bmp_icon_warning, _("Abort"), _("Continue"), NULL,
_("Unable to show"), _("EIP-712 data."), NULL,
_("Sign at your own risk."), NULL, NULL);
@ -245,6 +301,7 @@ void fsm_msgEthereumSignTypedHash(const EthereumSignTypedHash *msg) {
uint8_t pubkeyhash[20] = {0};
if (!hdnode_get_ethereum_pubkeyhash(node, pubkeyhash)) {
layoutHome();
return;
}

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