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-rw-r--r--tdeioslave/sftp/tdeio_sftp.cpp255
-rw-r--r--tdeioslave/sftp/tdeio_sftp.h19
2 files changed, 196 insertions, 78 deletions
diff --git a/tdeioslave/sftp/tdeio_sftp.cpp b/tdeioslave/sftp/tdeio_sftp.cpp
index cc086d5aa..59428ea22 100644
--- a/tdeioslave/sftp/tdeio_sftp.cpp
+++ b/tdeioslave/sftp/tdeio_sftp.cpp
@@ -33,6 +33,8 @@
#include <tqfile.h>
#include <tqdir.h>
+#include <functional>
+
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
@@ -92,6 +94,50 @@ extern "C"
}
}
+// Some helper functions/classes
+namespace {
+
+// A quick and dirty scope guard implementation
+class ExitGuard {
+public:
+ template<class Callable>
+ ExitGuard(Callable && undo_func) : f(std::forward<Callable>(undo_func)) {}
+ ExitGuard(ExitGuard && other) : f(std::move(other.f)) {
+ other.f = nullptr;
+ }
+
+ ~ExitGuard() {
+ run();
+ }
+
+ void run() noexcept {
+ if(f) { f(); f = nullptr; }
+ }
+
+ ExitGuard(const ExitGuard&) = delete;
+ void operator= (const ExitGuard&) = delete;
+
+private:
+ std::function<void()> f;
+};
+
+// A small helper to purge passwords. Paranoiac's note: this is not enough to guarantee the
+// complete purge of the password and all its copy from memory (ioslaves are sending the passwords
+// via dcop, so it's far beyond calling it "secure" in any way), but it's still better than nothing.
+void purgeString(TQString &s) {
+ s.fill('\0');
+ s.setLength(0);
+ s = TQString::null;
+}
+
+// A helper class to cleanup password when it goes out of the scope
+class PasswordPurger: public ExitGuard {
+public:
+ PasswordPurger(TQString &pw) : ExitGuard( [&pw](){purgeString(pw);} ) {}
+};
+
+} /* namespace */
+
// The callback function for libssh
int auth_callback(const char *prompt, char *buf, size_t len,
int echo, int verify, void *userdata)
@@ -128,42 +174,73 @@ int sftpProtocol::auth_callback(const char *prompt, char *buf, size_t len,
(void) echo;
(void) verify;
(void) userdata;
+ (void) prompt;
+
+ Q_ASSERT(len>0);
kdDebug(TDEIO_SFTP_DB) << "Entering public key authentication callback" << endl;
- if(!pubKeyInfo)
- {
- pubKeyInfo = new TDEIO::AuthInfo;
- }
- else
- {
- // TODO: inform user about incorrect password
- }
+ int rc=0;
+ mPubKeyAuthData.wasCalled = true;
- pubKeyInfo->url.setProtocol("sftp");
- pubKeyInfo->url.setHost(mHost);
- pubKeyInfo->url.setPort(mPort);
- pubKeyInfo->url.setUser(mUsername);
+ AuthInfo pubKeyInfo = authInfo();
- pubKeyInfo->caption = i18n("SFTP Login");
- pubKeyInfo->comment = "sftp://" + mUsername + "@" + mHost;
- pubKeyInfo->username = mUsername;
- pubKeyInfo->readOnly = false;
- pubKeyInfo->prompt = TQString::fromUtf8(prompt);
- pubKeyInfo->keepPassword = false; // don't save passwords for public key,
+ pubKeyInfo.readOnly = false;
+ pubKeyInfo.keepPassword = false; // don't save passwords for public key,
// that's the task of ssh-agent.
+ TQString errMsg;
+ TQString keyFile;
+#if LIBSSH_VERSION_INT < SSH_VERSION_INT(0, 10, 0)
+ // no way to determine keyfile name on older libssh
+#else
+ char *ssh_key_file = 0;
+ rc = ssh_userauth_publickey_auto_get_current_identity(mSession, &ssh_key_file);
- if (!openPassDlg(*pubKeyInfo)) {
- kdDebug(TDEIO_SFTP_DB) << "User canceled entry of public key password." << endl;
- return -1;
+ if (rc == 0 && ssh_key_file && ssh_key_file[0]) {
+ keyFile = ssh_key_file;
}
+ ssh_string_free_char(ssh_key_file);
+#endif
- strncpy(buf, pubKeyInfo->password.utf8().data(), len - 1);
+ bool firstTry = !mPubKeyAuthData.attemptedKeys.contains(keyFile);
- pubKeyInfo->password.fill('x');
- pubKeyInfo->password = "";
+ if (!firstTry) {
+ errMsg = i18n("Incorrect or invalid passphrase.");
+ }
- return 0;
+ // libssh prompt is trash and we know we use this function only for publickey auth, so we'll give
+ // the user a descent prompt
+ if (!keyFile.isEmpty()) {
+ pubKeyInfo.prompt = i18n("Please enter the passphrase for next public key:\n%1").arg(keyFile);
+ } else { // Generally shouldn't happend but on older libssh
+ pubKeyInfo.prompt = i18n("Please enter the passphrase for your public key.");
+ }
+
+ // We don't want to clobber with normal passwords in kpasswdserver's cache
+ pubKeyInfo.realmValue = "keyfile passphrase:" + keyFile;
+
+ if (openPassDlg(pubKeyInfo, errMsg)) {
+ if (len < pubKeyInfo.password.utf8().length()+1) {
+ kdDebug(TDEIO_SFTP_DB) << "Insufficient buffer size for password: " << len
+ << " (" << pubKeyInfo.password.utf8().length()+1 << "needed)" << endl;
+ }
+
+ strncpy(buf, pubKeyInfo.password.utf8().data(), len-1);
+ buf[len-1]=0; // Just to be on the safe side
+
+ purgeString(pubKeyInfo.password);
+ } else {
+ kdDebug(TDEIO_SFTP_DB) << "User canceled entry of public key passphrase" << endl;
+ rc = -1;
+ mPubKeyAuthData.wasCanceled = true;
+ }
+
+ // take a note that we already tried unlocking this keyfile
+ if(firstTry) {
+ mPubKeyAuthData.attemptedKeys.append(keyFile);
+ }
+
+ return rc;
}
void sftpProtocol::log_callback(ssh_session session, int priority,
@@ -210,6 +287,15 @@ int sftpProtocol::authenticateKeyboardInteractive(AuthInfo &info) {
kdDebug(TDEIO_SFTP_DB) << "prompt=" << prompt << " echo=" << TQString::number(echo) << endl;
TDEIO::AuthInfo infoKbdInt(info);
+ infoKbdInt.keepPassword = false;
+
+ if (!name.isEmpty()) {
+ infoKbdInt.caption = TQString(i18n("SFTP Login") + " - " + name);
+ }
+
+ // Those strings might or might not contain some sensitive information
+ PasswordPurger answerPurger{answer};
+ PasswordPurger infoPurger{infoKbdInt.password};
if (!echo) {
// ssh server requests us to ask user a question without displaying an answer. In normal
@@ -230,7 +316,6 @@ int sftpProtocol::authenticateKeyboardInteractive(AuthInfo &info) {
// If the server's request doesn't look like a password, keep the servers prompt and
// don't bother saving it
infoKbdInt.prompt = prompt;
- infoKbdInt.keepPassword = false;
}
infoKbdInt.readOnly = true; // set username readonly
@@ -242,6 +327,7 @@ int sftpProtocol::authenticateKeyboardInteractive(AuthInfo &info) {
answer = infoKbdInt.password;
if(isPassword) {
info.password = infoKbdInt.password; // return the answer to the caller
+ info.setModified( true );
}
} else {
/* FIXME: Some reasonable action upon cancellation? <2024-01-10 Fat-Zer> */
@@ -253,22 +339,16 @@ int sftpProtocol::authenticateKeyboardInteractive(AuthInfo &info) {
// no means of handle that correctly, so we will have to be creative with the password
// dialog.
TQString newPrompt;
- infoKbdInt.comment = "sftp://" + infoKbdInt.username + "@" + mHost;
-
- if (!name.isEmpty()) {
- infoKbdInt.caption = TQString(i18n("SFTP Login") + " - " + name);
- }
if (!instruction.isEmpty()) {
newPrompt = instruction + "\n\n";
}
-
newPrompt.append(prompt + "\n\n");
- infoKbdInt.readOnly = false;
- infoKbdInt.keepPassword = false;
newPrompt.append(i18n("Use the username input field to answer this question."));
infoKbdInt.prompt = newPrompt;
+ infoKbdInt.readOnly = false;
+
if (openPassDlg(infoKbdInt)) {
answer = infoKbdInt.username;
kdDebug(TDEIO_SFTP_DB) << "Got the answer from the password dialog: " << answer << endl;
@@ -289,6 +369,22 @@ int sftpProtocol::authenticateKeyboardInteractive(AuthInfo &info) {
return err;
}
+TDEIO::AuthInfo sftpProtocol::authInfo() {
+ TDEIO::AuthInfo rv;
+
+ rv.url.setProtocol("sftp");
+ rv.url.setHost(mHost);
+ rv.url.setPort(mPort);
+ rv.url.setUser(mUsername);
+
+ rv.caption = i18n("SFTP Login");
+ rv.comment = "sftp://" + mHost + ':' + TQString::number(mPort);
+ rv.commentLabel = i18n("site:");
+ rv.username = mUsername;
+
+ return rv;
+}
+
void sftpProtocol::reportError(const KURL &url, const int err) {
kdDebug(TDEIO_SFTP_DB) << "url = " << url.url() << " - err=" << err << endl;
@@ -553,18 +649,12 @@ void sftpProtocol::openConnection() {
// Setup AuthInfo for use with password caching and the
// password dialog box.
- AuthInfo info;
-
- info.url.setProtocol("sftp");
- info.url.setHost(mHost);
- info.url.setPort(mPort);
- info.url.setUser(mUsername);
- info.caption = i18n("SFTP Login");
- info.comment = "sftp://" + mHost + ':' + TQString::number(mPort);
- info.commentLabel = i18n("site:");
- info.username = mUsername;
+ AuthInfo info = authInfo();
info.keepPassword = true; // make the "keep Password" check box visible to the user.
+ PasswordPurger pwPurger{mPassword};
+ PasswordPurger infoPurger{info.password};
+
// Check for cached authentication info if no password is specified...
if (mPassword.isEmpty()) {
kdDebug(TDEIO_SFTP_DB) << "checking cache: info.username = " << info.username
@@ -631,8 +721,8 @@ void sftpProtocol::openConnection() {
}
// Set the username
- if (!mUsername.isEmpty()) {
- rc = ssh_options_set(mSession, SSH_OPTIONS_USER, mUsername.utf8().data());
+ if (!info.username.isEmpty()) {
+ rc = ssh_options_set(mSession, SSH_OPTIONS_USER, info.username.utf8().data());
if (rc < 0) {
error(TDEIO::ERR_OUT_OF_MEMORY, i18n("Could not set username."));
return;
@@ -793,25 +883,54 @@ void sftpProtocol::openConnection() {
bool firstTime = true;
bool dlgResult;
while (rc != SSH_AUTH_SUCCESS) {
+ /* FIXME: if there are problems with auth we are likely to stuck in this loop <2024-01-20 Fat-Zer> */
+
// Try to authenticate with public key first
- if (rc != SSH_AUTH_SUCCESS && (method & SSH_AUTH_METHOD_PUBLICKEY) && !mPassword)
- {
+ if (rc != SSH_AUTH_SUCCESS && (method & SSH_AUTH_METHOD_PUBLICKEY) && !mPassword) {
+ // might mess up next login attempt if we won't clean it up
+ ExitGuard pubKeyInfoCleanser([this]() {
+ mPubKeyAuthData.wasCalled = 0;
+ mPubKeyAuthData.wasCanceled = 0;
+ mPubKeyAuthData.attemptedKeys.clear();
+ });
+
kdDebug(TDEIO_SFTP_DB) << "Trying to authenticate with public key" << endl;
- for(;;)
+ bool keepTryingPasskey=true;
+ while(keepTryingPasskey)
{
+ mPubKeyAuthData.wasCalled = 0;
rc = ssh_userauth_publickey_auto(mSession, nullptr, nullptr);
- if (rc == SSH_AUTH_ERROR)
- {
- clearPubKeyAuthInfo();
- closeConnection();
- error(TDEIO::ERR_COULD_NOT_LOGIN, i18n("Authentication failed (method: %1).")
- .arg(i18n("public key")));
- return;
- }
- if (rc == SSH_AUTH_DENIED || !pubKeyInfo || !pubKeyInfo->isModified())
- {
- clearPubKeyAuthInfo();
- break;
+
+ kdDebug(TDEIO_SFTP_DB) << "ssh_userauth_publickey_auto returned rc=" << rc
+ << " ssh_err=" << ssh_get_error_code(mSession)
+ << " (" << ssh_get_error(mSession) << ")" << endl;
+
+ switch (rc) {
+ case SSH_AUTH_SUCCESS:
+ case SSH_AUTH_PARTIAL:
+ keepTryingPasskey=false;
+ break;
+ case SSH_AUTH_AGAIN:
+ // Returned in case of some errors like if server hangs up or there were too many auth attempts
+ case SSH_AUTH_ERROR:
+ closeConnection();
+ /* FIXME: Use scope guard to close connection <2024-01-20 Fat-Zer> */
+ error(TDEIO::ERR_COULD_NOT_LOGIN, i18n("Authentication failed (method: %1).")
+ .arg(i18n("public key")));
+ /* FIXME: add some additional info from ssh_get_error() if available <2024-01-20 Fat-Zer> */
+ return;
+
+ case SSH_AUTH_DENIED:
+ if (!mPubKeyAuthData.wasCalled) {
+ kdDebug(TDEIO_SFTP_DB) << "Passkey auth denied because it has no matching key" << endl;
+ keepTryingPasskey = false;
+ } else if (mPubKeyAuthData.wasCanceled) {
+ kdDebug(TDEIO_SFTP_DB) << "Passkey auth denied because user canceled" << endl;
+ keepTryingPasskey = false;
+ } else {
+ kdDebug(TDEIO_SFTP_DB) << "User entered wrong passphrase for the key" << endl;
+ }
+ break;
}
}
}
@@ -923,11 +1042,6 @@ void sftpProtocol::openConnection() {
mConnected = true;
connected();
- mPassword.fill('x');
- mPassword = "";
- info.password.fill('x');
- info.password = "";
-
return;
}
@@ -1875,12 +1989,3 @@ void sftpProtocol::slave_status() {
kdDebug(TDEIO_SFTP_DB) << "connected to " << mHost << "?: " << mConnected << endl;
slaveStatus((mConnected ? mHost : TQString()), mConnected);
}
-
-void sftpProtocol::clearPubKeyAuthInfo()
-{
- if (!pubKeyInfo)
- {
- delete pubKeyInfo;
- pubKeyInfo = nullptr;
- }
-}
diff --git a/tdeioslave/sftp/tdeio_sftp.h b/tdeioslave/sftp/tdeio_sftp.h
index 8e46d815c..2ad069ea7 100644
--- a/tdeioslave/sftp/tdeio_sftp.h
+++ b/tdeioslave/sftp/tdeio_sftp.h
@@ -31,6 +31,7 @@
#include <tdeio/slavebase.h>
#include <kdebug.h>
#include <stdint.h>
+#include <memory>
#include <libssh/libssh.h>
#include <libssh/sftp.h>
@@ -138,12 +139,24 @@ private: // Private variables
// TQString text;
//};
- TDEIO::AuthInfo *pubKeyInfo;
+ /** Some data needed to interact with auth_callback() */
+ struct {
+ /** true if callback was called */
+ bool wasCalled;
+ /** true if user canceled password entry dialog */
+ bool wasCanceled;
+ /** List of keys user was already prompted to enter the passphrase for.
+ * Note: Under most sane circumstances the list shouldn't go beyond size=2,
+ * so no fancy containers here
+ */
+ TQStringList attemptedKeys;
+ } mPubKeyAuthData;
private: // private methods
-
int authenticateKeyboardInteractive(TDEIO::AuthInfo &info);
- void clearPubKeyAuthInfo();
+
+ /** A small helper function to construct auth info skeleton for the protocol */
+ TDEIO::AuthInfo authInfo();
void reportError(const KURL &url, const int err);
generated by cgit v1.2.1 (git 2.18.0) at 2024-12-19 12:07:26 +0000