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GUACAMOLE-547: Merge support for SSH NONE authentication method.

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Mike Jumper 2019-06-20 00:46:55 -07:00 committed by GitHub
commit 7e9b97007e
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5 changed files with 92 additions and 30 deletions
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44
src/common-ssh/common-ssh/ssh.h
View File

@ -25,6 +25,23 @@
#include <guacamole/client.h>
#include <libssh2.h>
/**
* Handler for retrieving additional credentials.
*
* @param client
* The Guacamole Client associated with this need for additional
* credentials.
*
* @param cred_name
* The name of the credential being requested, which will be shared
* with the client in order to generate a meaningful prompt.
*
* @return
* A newly-allocated string containing the credentials provided by
* the user, which must be freed by a call to free().
*/
typedef char* guac_ssh_credential_handler(guac_client* client, char* cred_name);
/**
* An SSH session, backed by libssh2 and associated with a particular
* Guacamole client.
@ -51,6 +68,11 @@ typedef struct guac_common_ssh_session {
*/
int fd;
/**
* Callback function to retrieve credentials.
*/
guac_ssh_credential_handler* credential_handler;
} guac_common_ssh_session;
/**
@ -93,13 +115,31 @@ void guac_common_ssh_uninit();
* @param user
* The user to authenticate as, once connected.
*
* @param keepalive
* How frequently the connection should send keepalive packets, in
* seconds. Zero disables keepalive packets, and 2 is the minimum
* configurable value.
*
* @param host_key
* The known public host key of the server, as provided by the client. If
* provided the identity of the server will be checked against this key,
* and a mis-match between this and the server identity will cause the
* connection to fail. If not provided, no checks will be done and the
* connection will proceed.
*
* @param credential_handler
* The handler function for retrieving additional credentials from the user
* as required by the SSH server, or NULL if the user will not be asked
* for additional credentials.
*
* @return
* A new SSH session if the connection and authentication succeed, or NULL
* if the connection or authentication were not successful.
*/
guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
const char* hostname, const char* port, guac_common_ssh_user* user, int keepalive,
const char* host_key);
const char* hostname, const char* port, guac_common_ssh_user* user,
int keepalive, const char* host_key,
guac_ssh_credential_handler* credential_handler);
/**
* Disconnects and destroys the given SSH session, freeing all associated

34
src/common-ssh/ssh.c
View File

@ -304,20 +304,26 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
LIBSSH2_SESSION* session = common_session->session;
/* Get user credentials */
char* username = user->username;
char* password = user->password;
guac_common_ssh_key* key = user->private_key;
/* Validate username provided */
if (username == NULL) {
if (user->username == NULL) {
guac_client_abort(client, GUAC_PROTOCOL_STATUS_CLIENT_UNAUTHORIZED,
"SSH authentication requires a username.");
return 1;
}
/* Get list of supported authentication methods */
char* user_authlist = libssh2_userauth_list(session, username,
strlen(username));
char* user_authlist = libssh2_userauth_list(session, user->username,
strlen(user->username));
/* If auth list is NULL, then authentication has succeeded with NONE */
if (user_authlist == NULL) {
guac_client_log(client, GUAC_LOG_DEBUG,
"SSH NONE authentication succeeded.");
return 0;
}
guac_client_log(client, GUAC_LOG_DEBUG,
"Supported authentication methods: %s", user_authlist);
@ -333,7 +339,7 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
}
/* Attempt public key auth */
if (libssh2_userauth_publickey(session, username,
if (libssh2_userauth_publickey(session, user->username,
(unsigned char*) key->public_key, key->public_key_length,
guac_common_ssh_sign_callback, (void**) key)) {
@ -352,14 +358,18 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
}
/* Attempt authentication with username + password. */
if (user->password == NULL && common_session->credential_handler)
user->password = common_session->credential_handler(client, "Password: ");
/* Authenticate with password, if provided */
else if (password != NULL) {
if (user->password != NULL) {
/* Check if password auth is supported on the server */
if (strstr(user_authlist, "password") != NULL) {
/* Attempt password authentication */
if (libssh2_userauth_password(session, username, password)) {
if (libssh2_userauth_password(session, user->username, user->password)) {
/* Abort on failure */
char* error_message;
@ -380,7 +390,7 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
if (strstr(user_authlist, "keyboard-interactive") != NULL) {
/* Attempt keyboard-interactive auth using provided password */
if (libssh2_userauth_keyboard_interactive(session, username,
if (libssh2_userauth_keyboard_interactive(session, user->username,
&guac_common_ssh_kbd_callback)) {
/* Abort on failure */
@ -415,8 +425,9 @@ static int guac_common_ssh_authenticate(guac_common_ssh_session* common_session)
}
guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
const char* hostname, const char* port, guac_common_ssh_user* user, int keepalive,
const char* host_key) {
const char* hostname, const char* port, guac_common_ssh_user* user,
int keepalive, const char* host_key,
guac_ssh_credential_handler* credential_handler) {
int retval;
@ -561,6 +572,7 @@ guac_common_ssh_session* guac_common_ssh_create_session(guac_client* client,
common_session->user = user;
common_session->session = session;
common_session->fd = fd;
common_session->credential_handler = credential_handler;
/* Attempt authentication */
if (guac_common_ssh_authenticate(common_session)) {

2
src/protocols/rdp/rdp.c
View File

@ -975,7 +975,7 @@ void* guac_rdp_client_thread(void* data) {
rdp_client->sftp_session =
guac_common_ssh_create_session(client, settings->sftp_hostname,
settings->sftp_port, rdp_client->sftp_user, settings->sftp_server_alive_interval,
settings->sftp_host_key);
settings->sftp_host_key, NULL);
/* Fail if SSH connection does not succeed */
if (rdp_client->sftp_session == NULL) {

40
src/protocols/ssh/ssh.c
View File

@ -130,19 +130,6 @@ static guac_common_ssh_user* guac_ssh_get_user(guac_client* client) {
} /* end if key given */
/* Otherwise, use password */
else {
/* Get password if not provided */
if (settings->password == NULL)
settings->password = guac_terminal_prompt(ssh_client->term,
"Password: ", false);
/* Set provided password */
guac_common_ssh_user_set_password(user, settings->password);
}
/* Clear screen of any prompts */
guac_terminal_printf(ssh_client->term, "\x1B[H\x1B[J");
@ -150,6 +137,29 @@ static guac_common_ssh_user* guac_ssh_get_user(guac_client* client) {
}
/**
* A function used to generate a terminal prompt to gather additional
* credentials from the guac_client during a connection, and using
* the specified string to generate the prompt for the user.
*
* @param client
* The guac_client object associated with the current connection
* where additional credentials are required.
*
* @param cred_name
* The prompt text to display to the screen when prompting for the
* additional credentials.
*
* @return
* The string of credentials gathered from the user.
*/
static char* guac_ssh_get_credential(guac_client *client, char* cred_name) {
guac_ssh_client* ssh_client = (guac_ssh_client*) client->data;
return guac_terminal_prompt(ssh_client->term, cred_name, false);
}
void* ssh_input_thread(void* data) {
guac_client* client = (guac_client*) data;
@ -239,7 +249,7 @@ void* ssh_client_thread(void* data) {
/* Open SSH session */
ssh_client->session = guac_common_ssh_create_session(client,
settings->hostname, settings->port, ssh_client->user, settings->server_alive_interval,
settings->host_key);
settings->host_key, guac_ssh_get_credential);
if (ssh_client->session == NULL) {
/* Already aborted within guac_common_ssh_create_session() */
return NULL;
@ -291,7 +301,7 @@ void* ssh_client_thread(void* data) {
ssh_client->sftp_session =
guac_common_ssh_create_session(client, settings->hostname,
settings->port, ssh_client->user, settings->server_alive_interval,
settings->host_key);
settings->host_key, NULL);
if (ssh_client->sftp_session == NULL) {
/* Already aborted within guac_common_ssh_create_session() */
return NULL;

2
src/protocols/vnc/vnc.c
View File

@ -262,7 +262,7 @@ void* guac_vnc_client_thread(void* data) {
vnc_client->sftp_session =
guac_common_ssh_create_session(client, settings->sftp_hostname,
settings->sftp_port, vnc_client->sftp_user, settings->sftp_server_alive_interval,
settings->sftp_host_key);
settings->sftp_host_key, NULL);
/* Fail if SSH connection does not succeed */
if (vnc_client->sftp_session == NULL) {