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fix(security): scrub in-memory key/passphrase copies in the wallet secret paths (W4-1, W4-3, W2-3)

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The wallet-hardening memzero cluster. Uses the file's established sodium_memzero
pattern (matching the existing lambda-capture scrub at app_network.cpp:2885 and the JSON
scrub at :4025) rather than a new type, since importPrivateKey/sweepPrivateKey are
fund-moving code.

- W4-1 importPrivateKey / sweepPrivateKey: the spending/viewing key was copied ≥3×
  (calling frame -> worker-lambda capture -> JSON params) and never scrubbed. Now zeroed
  on all paths: the calling-frame copy after the worker post, the lambda's captured copy
  (lambda made mutable, zeroed once the request is sent), and the request params copy.

- W4-3 exportAllKeys / backupWallet: the concatenated all-keys buffer is now zeroed after
  the consumer uses it, and the backup is written via
  Platform::writeFileAtomically(..., restrictPermissions=true) — atomic and owner-only
  (0600) — instead of a umask-default std::ofstream that left it world-readable.

- W2-3 decrypt-wallet passphrase: std::move-captured into the worker lambda (no plaintext
  copy left in the calling frame) and sodium_memzero'd right after unlockWallet, its only
  use.

Not unit-testable (no observable RPC effect — the key value sent to the daemon is
unchanged; only post-use memory zeroing is added). Build-clean; ctest 1/1. See
docs/wallet-hardening.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
DanS
2026-08-02 14:12:44 -05:00
parent 9204fa148a
commit f9b622cb25
3 changed files with 35 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
src/app_network.cpp
View File

@@ -3783,6 +3783,8 @@ void App::exportAllKeys(std::function<void(const std::string&, int, int)> callba
(*pending)--;
if (*pending == 0 && callback) {
callback(*keys_result, *exported, *total);
// Scrub the concatenated all-keys buffer once the consumer (backup writer) has used it.
if (!keys_result->empty()) sodium_memzero(&(*keys_result)[0], keys_result->size());
}
});
}
@@ -3814,7 +3816,7 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
== services::WalletSecurityController::KeyKind::Shielded;
// Run on the worker thread — import requests a full rescan (rescan=true), so the
// synchronous curl call can take many seconds; never block the UI thread on it.
worker_->post([this, key, viewing, shielded, startHeight, callback]() -> rpc::RPCWorker::MainCb {
worker_->post([this, key, viewing, shielded, startHeight, callback]() mutable -> rpc::RPCWorker::MainCb {
std::string err, addr;
try {
rpc::RPCClient::TraceScope trace("Settings / Import key");
@@ -3826,6 +3828,11 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
// A start height (shielded RPCs only) rescans from that block instead of genesis.
if (startHeight > 0 && (viewing || shielded)) params.push_back(startHeight);
nlohmann::json r = rpc_->call(method, params);
// Scrub the key out of the request params (the json holds its own copy of it).
if (params.is_array() && !params.empty() && params[0].is_string()) {
std::string& pk = params[0].get_ref<std::string&>();
if (!pk.empty()) sodium_memzero(&pk[0], pk.size());
}
// z_import* return {type,address}; importprivkey returns the t-address string.
if (r.is_object() && r.contains("address") && r["address"].is_string())
addr = r["address"].get<std::string>();
@@ -3838,6 +3845,8 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
// below would never run, leaving a stuck "Importing…" spinner.
err = "Import failed (unknown error)";
}
// Scrub the worker's copy of the key now that the request has been sent (all paths).
if (!key.empty()) sodium_memzero(&key[0], key.size());
return [this, err, addr, callback]() {
if (!err.empty()) {
if (callback) callback(false, err, "");
@@ -3848,6 +3857,7 @@ void App::importPrivateKey(const std::string& rawKey, int startHeight,
if (callback) callback(true, "", addr);
};
});
if (!key.empty()) sodium_memzero(&key[0], key.size()); // scrub the calling-frame copy
}
// Sweep a spending key: import it (a full rescan populates its UTXOs/notes — the stock node has no
@@ -3885,7 +3895,7 @@ void App::sweepPrivateKey(const std::string& rawKey, int startHeight, int destMo
const bool shielded = services::WalletSecurityController::classifyPrivateKey(key)
== services::WalletSecurityController::KeyKind::Shielded;
const double fee = DRAGONX_DEFAULT_FEE;
worker_->post([this, key, startHeight, destMode, destExisting, shielded, fee]() -> rpc::RPCWorker::MainCb {
worker_->post([this, key, startHeight, destMode, destExisting, shielded, fee]() mutable -> rpc::RPCWorker::MainCb {
std::string err, dest, sourceAddr, amountStr;
double amount = 0.0;
try {
@@ -3909,6 +3919,11 @@ void App::sweepPrivateKey(const std::string& rawKey, int startHeight, int destMo
else { method = "importprivkey"; params = {key, "", true}; }
if (startHeight > 0 && shielded) params.push_back(startHeight);
nlohmann::json r = rpc_->call(method, params);
// Scrub the key out of the request params (the json holds its own copy of it).
if (params.is_array() && !params.empty() && params[0].is_string()) {
std::string& pk = params[0].get_ref<std::string&>();
if (!pk.empty()) sodium_memzero(&pk[0], pk.size());
}
// 2. Determine the swept address. importprivkey returns the t-address string; z_importkey
// returns null, so diff the z-address list to find the one the key just added.
@@ -3967,6 +3982,8 @@ void App::sweepPrivateKey(const std::string& rawKey, int startHeight, int destMo
} catch (...) {
err = "Sweep failed (unknown error)";
}
// Scrub the worker's copy of the spending key now that the request has been sent (all paths).
if (!key.empty()) sodium_memzero(&key[0], key.size());
return [this, err, sourceAddr, dest, amount, amountStr, fee]() {
invalidateAddressValidationCache();
refreshAddresses();
@@ -4003,6 +4020,7 @@ void App::sweepPrivateKey(const std::string& rawKey, int startHeight, int destMo
});
};
});
if (!key.empty()) sodium_memzero(&key[0], key.size()); // scrub the calling-frame copy
}
void App::exportSeedPhrase(std::function<void(bool, bool, const std::string&, const std::string&)> callback)
@@ -4478,13 +4496,12 @@ void App::backupWallet(const std::string& destination, std::function<void(bool,
return;
}
std::ofstream file(destination);
if (!file.is_open()) {
if (callback) callback(false, "Could not open file: " + destination);
// Write the key backup atomically and owner-only (0600) — it must never be even briefly
// world-readable, and the previous std::ofstream left it at the umask default.
if (!util::Platform::writeFileAtomically(destination, keys, /*restrictPermissions=*/true)) {
if (callback) callback(false, "Could not write file: " + destination);
return;
}
file << keys;
file.close();
std::string msg = "Wallet backup saved to " + destination + " — "
+ std::to_string(exported) + " of " + std::to_string(total) + " keys.";