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libssh/src/server.c
Jon Simons 5865b9436f kex: server fix for first_kex_packet_follows 
Ensure to honor the 'first_kex_packet_follow' field when processing
KEXINIT messages in the 'ssh_packet_kexinit' callback.  Until now
libssh would assume that this field is always unset (zero).  But
some clients may set this (dropbear at or beyond version 2013.57),
and it needs to be included when computing the session ID.

Also include logic for handling wrongly-guessed key exchange algorithms.
Save whether a client's guess is wrong in a new field in the session
struct: when set, the next KEX_DHINIT message to be processed will be
ignored per RFC 4253, 7.1.

While here, update both 'ssh_packet_kexinit' and 'make_sessionid' to
use softabs with a 4 space indent level throughout, and also convert
various error-checking to store intermediate values into an explicit
'rc'.

Signed-off-by: Jon Simons <jon@jonsimons.org>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
2014-04-10 08:54:10 +02:00

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/*
* server.c - functions for creating a SSH server
*
* This file is part of the SSH Library
*
* Copyright (c) 2004-2013 by Aris Adamantiadis
*
* The SSH Library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The SSH Library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the SSH Library; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "config.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#ifdef _WIN32
# include <winsock2.h>
# include <ws2tcpip.h>
/*
* <wspiapi.h> is necessary for getaddrinfo before Windows XP, but it isn't
* available on some platforms like MinGW.
*/
# ifdef HAVE_WSPIAPI_H
# include <wspiapi.h>
# endif
#else
# include <netinet/in.h>
#endif
#include "libssh/priv.h"
#include "libssh/libssh.h"
#include "libssh/server.h"
#include "libssh/ssh2.h"
#include "libssh/buffer.h"
#include "libssh/packet.h"
#include "libssh/socket.h"
#include "libssh/session.h"
#include "libssh/kex.h"
#include "libssh/misc.h"
#include "libssh/pki.h"
#include "libssh/dh.h"
#include "libssh/messages.h"
#include "libssh/options.h"
#include "libssh/curve25519.h"
#define set_status(session, status) do {\
if (session->common.callbacks && session->common.callbacks->connect_status_function) \
session->common.callbacks->connect_status_function(session->common.callbacks->userdata, status); \
} while (0)
static int dh_handshake_server(ssh_session session);
/**
* @addtogroup libssh_server
*
* @{
*/
/** @internal
* This functions sets the Key Exchange protocols to be accepted
* by the server. They depend on
* -What the user asked (via options)
* -What is available (keys)
* It should then accept the intersection of what the user asked
* and what is available, and return an error if nothing matches
*/
static int server_set_kex(ssh_session session) {
struct ssh_kex_struct *server = &session->next_crypto->server_kex;
int i, j, rc;
const char *wanted;
char hostkeys[64] = {0};
enum ssh_keytypes_e keytype;
size_t len;
ZERO_STRUCTP(server);
ssh_get_random(server->cookie, 16, 0);
#ifdef HAVE_ECC
if (session->srv.ecdsa_key != NULL) {
snprintf(hostkeys, sizeof(hostkeys),
"%s", session->srv.ecdsa_key->type_c);
}
#endif
if (session->srv.dsa_key != NULL) {
len = strlen(hostkeys);
keytype = ssh_key_type(session->srv.dsa_key);
snprintf(hostkeys + len, sizeof(hostkeys) - len,
",%s", ssh_key_type_to_char(keytype));
}
if (session->srv.rsa_key != NULL) {
len = strlen(hostkeys);
keytype = ssh_key_type(session->srv.rsa_key);
snprintf(hostkeys + len, sizeof(hostkeys) - len,
",%s", ssh_key_type_to_char(keytype));
}
if (strlen(hostkeys) == 0) {
return -1;
}
rc = ssh_options_set_algo(session,
SSH_HOSTKEYS,
hostkeys[0] == ',' ? hostkeys + 1 : hostkeys);
if (rc < 0) {
return -1;
}
for (i = 0; i < 10; i++) {
if ((wanted = session->opts.wanted_methods[i]) == NULL) {
wanted = ssh_kex_get_supported_method(i);
}
server->methods[i] = strdup(wanted);
if (server->methods[i] == NULL) {
for (j = 0; j < i; j++) {
SAFE_FREE(server->methods[j]);
}
return -1;
}
}
return 0;
}
/** @internal
* @brief parse an incoming SSH_MSG_KEXDH_INIT packet and complete
* key exchange
**/
static int ssh_server_kexdh_init(ssh_session session, ssh_buffer packet){
ssh_string e;
e = buffer_get_ssh_string(packet);
if (e == NULL) {
ssh_set_error(session, SSH_FATAL, "No e number in client request");
return -1;
}
if (dh_import_e(session, e) < 0) {
ssh_set_error(session, SSH_FATAL, "Cannot import e number");
session->session_state=SSH_SESSION_STATE_ERROR;
} else {
session->dh_handshake_state=DH_STATE_INIT_SENT;
dh_handshake_server(session);
}
ssh_string_free(e);
return SSH_OK;
}
SSH_PACKET_CALLBACK(ssh_packet_kexdh_init){
int rc;
(void)type;
(void)user;
SSH_LOG(SSH_LOG_PACKET,"Received SSH_MSG_KEXDH_INIT");
if(session->dh_handshake_state != DH_STATE_INIT){
SSH_LOG(SSH_LOG_RARE,"Invalid state for SSH_MSG_KEXDH_INIT");
goto error;
}
/* If first_kex_packet_follows guess was wrong, ignore this message. */
if (session->first_kex_follows_guess_wrong != 0) {
SSH_LOG(SSH_LOG_RARE, "first_kex_packet_follows guess was wrong, "
"ignoring first SSH_MSG_KEXDH_INIT message");
session->first_kex_follows_guess_wrong = 0;
goto error;
}
switch(session->next_crypto->kex_type){
case SSH_KEX_DH_GROUP1_SHA1:
case SSH_KEX_DH_GROUP14_SHA1:
rc=ssh_server_kexdh_init(session, packet);
break;
#ifdef HAVE_ECDH
case SSH_KEX_ECDH_SHA2_NISTP256:
rc = ssh_server_ecdh_init(session, packet);
break;
#endif
#ifdef HAVE_CURVE25519
case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
rc = ssh_server_curve25519_init(session, packet);
break;
#endif
default:
ssh_set_error(session,SSH_FATAL,"Wrong kex type in ssh_packet_kexdh_init");
rc = SSH_ERROR;
}
if (rc == SSH_ERROR)
session->session_state = SSH_SESSION_STATE_ERROR;
error:
return SSH_PACKET_USED;
}
int ssh_get_key_params(ssh_session session, ssh_key *privkey){
ssh_key pubkey;
ssh_string pubkey_blob;
int rc;
switch(session->srv.hostkey) {
case SSH_KEYTYPE_DSS:
*privkey = session->srv.dsa_key;
break;
case SSH_KEYTYPE_RSA:
case SSH_KEYTYPE_RSA1:
*privkey = session->srv.rsa_key;
break;
case SSH_KEYTYPE_ECDSA:
*privkey = session->srv.ecdsa_key;
break;
case SSH_KEYTYPE_UNKNOWN:
default:
*privkey = NULL;
}
rc = ssh_pki_export_privkey_to_pubkey(*privkey, &pubkey);
if (rc < 0) {
ssh_set_error(session, SSH_FATAL,
"Could not get the public key from the private key");
return -1;
}
rc = ssh_pki_export_pubkey_blob(pubkey, &pubkey_blob);
ssh_key_free(pubkey);
if (rc < 0) {
ssh_set_error_oom(session);
return -1;
}
dh_import_pubkey(session, pubkey_blob);
return SSH_OK;
}
static int dh_handshake_server(ssh_session session) {
ssh_key privkey;
//ssh_string pubkey_blob = NULL;
ssh_string sig_blob;
ssh_string f;
if (dh_generate_y(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not create y number");
return -1;
}
if (dh_generate_f(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not create f number");
return -1;
}
f = dh_get_f(session);
if (f == NULL) {
ssh_set_error(session, SSH_FATAL, "Could not get the f number");
return -1;
}
if (ssh_get_key_params(session,&privkey) != SSH_OK){
ssh_string_free(f);
return -1;
}
if (dh_build_k(session) < 0) {
ssh_set_error(session, SSH_FATAL, "Could not import the public key");
ssh_string_free(f);
return -1;
}
if (make_sessionid(session) != SSH_OK) {
ssh_set_error(session, SSH_FATAL, "Could not create a session id");
ssh_string_free(f);
return -1;
}
sig_blob = ssh_srv_pki_do_sign_sessionid(session, privkey);
if (sig_blob == NULL) {
ssh_set_error(session, SSH_FATAL, "Could not sign the session id");
ssh_string_free(f);
return -1;
}
if (buffer_add_u8(session->out_buffer, SSH2_MSG_KEXDH_REPLY) < 0 ||
buffer_add_ssh_string(session->out_buffer,
session->next_crypto->server_pubkey) < 0 ||
buffer_add_ssh_string(session->out_buffer, f) < 0 ||
buffer_add_ssh_string(session->out_buffer, sig_blob) < 0) {
ssh_set_error(session, SSH_FATAL, "Not enough space");
ssh_buffer_reinit(session->out_buffer);
ssh_string_free(f);
ssh_string_free(sig_blob);
return -1;
}
ssh_string_free(f);
ssh_string_free(sig_blob);
if (packet_send(session) == SSH_ERROR) {
return -1;
}
if (buffer_add_u8(session->out_buffer, SSH2_MSG_NEWKEYS) < 0) {
ssh_buffer_reinit(session->out_buffer);
return -1;
}
if (packet_send(session) == SSH_ERROR) {
return -1;
}
SSH_LOG(SSH_LOG_PACKET, "SSH_MSG_NEWKEYS sent");
session->dh_handshake_state=DH_STATE_NEWKEYS_SENT;
return 0;
}
/**
* @internal
*
* @brief A function to be called each time a step has been done in the
* connection.
*/
static void ssh_server_connection_callback(ssh_session session){
int ssh1,ssh2;
switch(session->session_state){
case SSH_SESSION_STATE_NONE:
case SSH_SESSION_STATE_CONNECTING:
case SSH_SESSION_STATE_SOCKET_CONNECTED:
break;
case SSH_SESSION_STATE_BANNER_RECEIVED:
if (session->clientbanner == NULL) {
goto error;
}
set_status(session, 0.4f);
SSH_LOG(SSH_LOG_RARE,
"SSH client banner: %s", session->clientbanner);
/* Here we analyze the different protocols the server allows. */
if (ssh_analyze_banner(session, 1, &ssh1, &ssh2) < 0) {
goto error;
}
/* Here we decide which version of the protocol to use. */
if (ssh2 && session->opts.ssh2) {
session->version = 2;
} else if (ssh1 && session->opts.ssh1) {
session->version = 1;
} else if (ssh1 && !session->opts.ssh1) {
#ifdef WITH_SSH1
ssh_set_error(session, SSH_FATAL,
"SSH-1 protocol not available (configure session to allow SSH-1)");
goto error;
#else
ssh_set_error(session, SSH_FATAL,
"SSH-1 protocol not available (libssh compiled without SSH-1 support)");
goto error;
#endif
} else {
ssh_set_error(session, SSH_FATAL,
"No version of SSH protocol usable (banner: %s)",
session->clientbanner);
goto error;
}
/* from now, the packet layer is handling incoming packets */
if(session->version==2)
session->socket_callbacks.data=ssh_packet_socket_callback;
#ifdef WITH_SSH1
else
session->socket_callbacks.data=ssh_packet_socket_callback1;
#endif
ssh_packet_set_default_callbacks(session);
set_status(session, 0.5f);
session->session_state=SSH_SESSION_STATE_INITIAL_KEX;
if (ssh_send_kex(session, 1) < 0) {
goto error;
}
break;
case SSH_SESSION_STATE_INITIAL_KEX:
/* TODO: This state should disappear in favor of get_key handle */
#ifdef WITH_SSH1
if(session->version==1){
if (ssh_get_kex1(session) < 0)
goto error;
set_status(session,0.6f);
session->connected = 1;
break;
}
#endif
break;
case SSH_SESSION_STATE_KEXINIT_RECEIVED:
set_status(session,0.6f);
if(session->next_crypto->server_kex.methods[0]==NULL){
if(server_set_kex(session) == SSH_ERROR)
goto error;
/* We are in a rekeying, so we need to send the server kex */
if(ssh_send_kex(session, 1) < 0)
goto error;
}
ssh_list_kex(&session->next_crypto->client_kex); // log client kex
if (ssh_kex_select_methods(session) < 0) {
goto error;
}
if (crypt_set_algorithms_server(session) == SSH_ERROR)
goto error;
set_status(session,0.8f);
session->session_state=SSH_SESSION_STATE_DH;
break;
case SSH_SESSION_STATE_DH:
if(session->dh_handshake_state==DH_STATE_FINISHED){
if (generate_session_keys(session) < 0) {
goto error;
}
/*
* Once we got SSH2_MSG_NEWKEYS we can switch next_crypto and
* current_crypto
*/
if (session->current_crypto) {
crypto_free(session->current_crypto);
}
/* FIXME TODO later, include a function to change keys */
session->current_crypto = session->next_crypto;
session->next_crypto = crypto_new();
if (session->next_crypto == NULL) {
goto error;
}
session->next_crypto->session_id = malloc(session->current_crypto->digest_len);
if (session->next_crypto->session_id == NULL) {
ssh_set_error_oom(session);
goto error;
}
memcpy(session->next_crypto->session_id, session->current_crypto->session_id,
session->current_crypto->digest_len);
set_status(session,1.0f);
session->connected = 1;
session->session_state=SSH_SESSION_STATE_AUTHENTICATING;
if (session->flags & SSH_SESSION_FLAG_AUTHENTICATED)
session->session_state = SSH_SESSION_STATE_AUTHENTICATED;
}
break;
case SSH_SESSION_STATE_AUTHENTICATING:
break;
case SSH_SESSION_STATE_ERROR:
goto error;
default:
ssh_set_error(session,SSH_FATAL,"Invalid state %d",session->session_state);
}
return;
error:
ssh_socket_close(session->socket);
session->alive = 0;
session->session_state=SSH_SESSION_STATE_ERROR;
}
/**
* @internal
*
* @brief Gets the banner from socket and saves it in session.
* Updates the session state
*
* @param data pointer to the beginning of header
* @param len size of the banner
* @param user is a pointer to session
* @returns Number of bytes processed, or zero if the banner is not complete.
*/
static int callback_receive_banner(const void *data, size_t len, void *user) {
char *buffer = (char *) data;
ssh_session session = (ssh_session) user;
char *str = NULL;
size_t i;
int ret=0;
for (i = 0; i < len; i++) {
#ifdef WITH_PCAP
if(session->pcap_ctx && buffer[i] == '\n') {
ssh_pcap_context_write(session->pcap_ctx,
SSH_PCAP_DIR_IN,
buffer,
i + 1,
i + 1);
}
#endif
if (buffer[i] == '\r') {
buffer[i]='\0';
}
if (buffer[i] == '\n') {
buffer[i]='\0';
str = strdup(buffer);
/* number of bytes read */
ret = i + 1;
session->clientbanner = str;
session->session_state = SSH_SESSION_STATE_BANNER_RECEIVED;
SSH_LOG(SSH_LOG_PACKET, "Received banner: %s", str);
session->ssh_connection_callback(session);
return ret;
}
if(i > 127) {
/* Too big banner */
session->session_state = SSH_SESSION_STATE_ERROR;
ssh_set_error(session, SSH_FATAL, "Receiving banner: too large banner");
return 0;
}
}
return ret;
}
/* returns 0 until the key exchange is not finished */
static int ssh_server_kex_termination(void *s){
ssh_session session = s;
if (session->session_state != SSH_SESSION_STATE_ERROR &&
session->session_state != SSH_SESSION_STATE_AUTHENTICATING &&
session->session_state != SSH_SESSION_STATE_DISCONNECTED)
return 0;
else
return 1;
}
/** Set the acceptable authentication methods to be sent to
* client.
* @param[in] session the SSH server session
* @param[in] auth_methods Bitfield of authentication methods
* to be accepted, e.g. SSH_AUTH_METHOD_PUBLICKEY
*/
void ssh_set_auth_methods(ssh_session session, int auth_methods){
/* accept only methods in range */
session->auth_methods = auth_methods & 0x3f;
}
/* Do the banner and key exchange */
int ssh_handle_key_exchange(ssh_session session) {
int rc;
if (session->session_state != SSH_SESSION_STATE_NONE)
goto pending;
rc = ssh_send_banner(session, 1);
if (rc < 0) {
return SSH_ERROR;
}
session->alive = 1;
session->ssh_connection_callback = ssh_server_connection_callback;
session->session_state = SSH_SESSION_STATE_SOCKET_CONNECTED;
ssh_socket_set_callbacks(session->socket,&session->socket_callbacks);
session->socket_callbacks.data=callback_receive_banner;
session->socket_callbacks.exception=ssh_socket_exception_callback;
session->socket_callbacks.userdata=session;
rc = server_set_kex(session);
if (rc < 0) {
return SSH_ERROR;
}
pending:
rc = ssh_handle_packets_termination(session, SSH_TIMEOUT_USER,
ssh_server_kex_termination,session);
SSH_LOG(SSH_LOG_PACKET, "ssh_handle_key_exchange: current state : %d",
session->session_state);
if (rc != SSH_OK)
return rc;
if (session->session_state == SSH_SESSION_STATE_ERROR ||
session->session_state == SSH_SESSION_STATE_DISCONNECTED) {
return SSH_ERROR;
}
return SSH_OK;
}
/* messages */
/** @internal
* replies to an SSH_AUTH packet with a default (denied) response.
*/
int ssh_auth_reply_default(ssh_session session,int partial) {
char methods_c[128] = {0};
ssh_string methods = NULL;
int rc = SSH_ERROR;
if (buffer_add_u8(session->out_buffer, SSH2_MSG_USERAUTH_FAILURE) < 0) {
return rc;
}
if (session->auth_methods == 0) {
session->auth_methods = SSH_AUTH_METHOD_PUBLICKEY | SSH_AUTH_METHOD_PASSWORD;
}
if (session->auth_methods & SSH_AUTH_METHOD_PUBLICKEY) {
strncat(methods_c, "publickey,",
sizeof(methods_c) - strlen(methods_c) - 1);
}
if (session->auth_methods & SSH_AUTH_METHOD_GSSAPI_MIC){
strncat(methods_c,"gssapi-with-mic,",
sizeof(methods_c) - strlen(methods_c) - 1);
}
if (session->auth_methods & SSH_AUTH_METHOD_INTERACTIVE) {
strncat(methods_c, "keyboard-interactive,",
sizeof(methods_c) - strlen(methods_c) - 1);
}
if (session->auth_methods & SSH_AUTH_METHOD_PASSWORD) {
strncat(methods_c, "password,",
sizeof(methods_c) - strlen(methods_c) - 1);
}
if (session->auth_methods & SSH_AUTH_METHOD_HOSTBASED) {
strncat(methods_c, "hostbased,",
sizeof(methods_c) - strlen(methods_c) - 1);
}
if (methods_c[0] == '\0' || methods_c[strlen(methods_c)-1] != ',') {
return SSH_ERROR;
}
/* Strip the comma. */
methods_c[strlen(methods_c) - 1] = '\0'; // strip the comma. We are sure there is at
SSH_LOG(SSH_LOG_PACKET,
"Sending a auth failure. methods that can continue: %s", methods_c);
methods = ssh_string_from_char(methods_c);
if (methods == NULL) {
goto error;
}
if (buffer_add_ssh_string(session->out_buffer, methods) < 0) {
goto error;
}
if (partial) {
if (buffer_add_u8(session->out_buffer, 1) < 0) {
goto error;
}
} else {
if (buffer_add_u8(session->out_buffer, 0) < 0) {
goto error;
}
}
rc = packet_send(session);
error:
ssh_string_free(methods);
return rc;
}
static int ssh_message_channel_request_open_reply_default(ssh_message msg) {
SSH_LOG(SSH_LOG_FUNCTIONS, "Refusing a channel");
if (buffer_add_u8(msg->session->out_buffer
, SSH2_MSG_CHANNEL_OPEN_FAILURE) < 0) {
goto error;
}
if (buffer_add_u32(msg->session->out_buffer,
htonl(msg->channel_request_open.sender)) < 0) {
goto error;
}
if (buffer_add_u32(msg->session->out_buffer,
htonl(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) < 0) {
goto error;
}
/* reason is an empty string */
if (buffer_add_u32(msg->session->out_buffer, 0) < 0) {
goto error;
}
/* language too */
if (buffer_add_u32(msg->session->out_buffer, 0) < 0) {
goto error;
}
return packet_send(msg->session);
error:
return SSH_ERROR;
}
static int ssh_message_channel_request_reply_default(ssh_message msg) {
uint32_t channel;
if (msg->channel_request.want_reply) {
channel = msg->channel_request.channel->remote_channel;
SSH_LOG(SSH_LOG_PACKET,
"Sending a default channel_request denied to channel %d", channel);
if (buffer_add_u8(msg->session->out_buffer, SSH2_MSG_CHANNEL_FAILURE) < 0) {
return SSH_ERROR;
}
if (buffer_add_u32(msg->session->out_buffer, htonl(channel)) < 0) {
return SSH_ERROR;
}
return packet_send(msg->session);
}
SSH_LOG(SSH_LOG_PACKET,
"The client doesn't want to know the request failed!");
return SSH_OK;
}
static int ssh_message_service_request_reply_default(ssh_message msg) {
/* The only return code accepted by specifications are success or disconnect */
return ssh_message_service_reply_success(msg);
}
int ssh_message_service_reply_success(ssh_message msg) {
struct ssh_string_struct *service;
ssh_session session;
if (msg == NULL) {
return SSH_ERROR;
}
session = msg->session;
SSH_LOG(SSH_LOG_PACKET,
"Sending a SERVICE_ACCEPT for service %s", msg->service_request.service);
if (buffer_add_u8(session->out_buffer, SSH2_MSG_SERVICE_ACCEPT) < 0) {
return -1;
}
service=ssh_string_from_char(msg->service_request.service);
if (service == NULL) {
return -1;
}
if (buffer_add_ssh_string(session->out_buffer, service) < 0) {
ssh_string_free(service);
return -1;
}
ssh_string_free(service);
return packet_send(msg->session);
}
int ssh_message_global_request_reply_success(ssh_message msg, uint16_t bound_port) {
SSH_LOG(SSH_LOG_FUNCTIONS, "Accepting a global request");
if (msg->global_request.want_reply) {
if (buffer_add_u8(msg->session->out_buffer
, SSH2_MSG_REQUEST_SUCCESS) < 0) {
goto error;
}
if(msg->global_request.type == SSH_GLOBAL_REQUEST_TCPIP_FORWARD
&& msg->global_request.bind_port == 0) {
if (buffer_add_u32(msg->session->out_buffer, htonl(bound_port)) < 0) {
goto error;
}
}
return packet_send(msg->session);
}
if(msg->global_request.type == SSH_GLOBAL_REQUEST_TCPIP_FORWARD
&& msg->global_request.bind_port == 0) {
SSH_LOG(SSH_LOG_PACKET,
"The client doesn't want to know the remote port!");
}
return SSH_OK;
error:
return SSH_ERROR;
}
static int ssh_message_global_request_reply_default(ssh_message msg) {
SSH_LOG(SSH_LOG_FUNCTIONS, "Refusing a global request");
if (msg->global_request.want_reply) {
if (buffer_add_u8(msg->session->out_buffer
, SSH2_MSG_REQUEST_FAILURE) < 0) {
goto error;
}
return packet_send(msg->session);
}
SSH_LOG(SSH_LOG_PACKET,
"The client doesn't want to know the request failed!");
return SSH_OK;
error:
return SSH_ERROR;
}
int ssh_message_reply_default(ssh_message msg) {
if (msg == NULL) {
return -1;
}
switch(msg->type) {
case SSH_REQUEST_AUTH:
return ssh_auth_reply_default(msg->session, 0);
case SSH_REQUEST_CHANNEL_OPEN:
return ssh_message_channel_request_open_reply_default(msg);
case SSH_REQUEST_CHANNEL:
return ssh_message_channel_request_reply_default(msg);
case SSH_REQUEST_SERVICE:
return ssh_message_service_request_reply_default(msg);
case SSH_REQUEST_GLOBAL:
return ssh_message_global_request_reply_default(msg);
default:
SSH_LOG(SSH_LOG_PACKET,
"Don't know what to default reply to %d type",
msg->type);
break;
}
return -1;
}
const char *ssh_message_service_service(ssh_message msg){
if (msg == NULL) {
return NULL;
}
return msg->service_request.service;
}
const char *ssh_message_auth_user(ssh_message msg) {
if (msg == NULL) {
return NULL;
}
return msg->auth_request.username;
}
const char *ssh_message_auth_password(ssh_message msg){
if (msg == NULL) {
return NULL;
}
return msg->auth_request.password;
}
ssh_key ssh_message_auth_pubkey(ssh_message msg) {
if (msg == NULL) {
return NULL;
}
return msg->auth_request.pubkey;
}
/* Get the publickey of an auth request */
ssh_public_key ssh_message_auth_publickey(ssh_message msg){
if (msg == NULL) {
return NULL;
}
return ssh_pki_convert_key_to_publickey(msg->auth_request.pubkey);
}
enum ssh_publickey_state_e ssh_message_auth_publickey_state(ssh_message msg){
if (msg == NULL) {
return -1;
}
return msg->auth_request.signature_state;
}
int ssh_message_auth_kbdint_is_response(ssh_message msg) {
if (msg == NULL) {
return -1;
}
return msg->auth_request.kbdint_response != 0;
}
int ssh_message_auth_set_methods(ssh_message msg, int methods) {
if (msg == NULL || msg->session == NULL) {
return -1;
}
msg->session->auth_methods = methods;
return 0;
}
int ssh_message_auth_interactive_request(ssh_message msg, const char *name,
const char *instruction, unsigned int num_prompts,
const char **prompts, char *echo) {
int r;
unsigned int i = 0;
ssh_string tmp = NULL;
if(name == NULL || instruction == NULL) {
return SSH_ERROR;
}
if(num_prompts > 0 && (prompts == NULL || echo == NULL)) {
return SSH_ERROR;
}
if (buffer_add_u8(msg->session->out_buffer, SSH2_MSG_USERAUTH_INFO_REQUEST) < 0) {
return SSH_ERROR;
}
/* name */
tmp = ssh_string_from_char(name);
if (tmp == NULL) {
return SSH_ERROR;
}
r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
ssh_string_free(tmp);
if (r < 0) {
return SSH_ERROR;
}
/* instruction */
tmp = ssh_string_from_char(instruction);
if (tmp == NULL) {
return SSH_ERROR;
}
r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
ssh_string_free(tmp);
if (r < 0) {
return SSH_ERROR;
}
/* language tag */
tmp = ssh_string_from_char("");
if (tmp == NULL) {
return SSH_ERROR;
}
r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
ssh_string_free(tmp);
if (r < 0) {
return SSH_ERROR;
}
/* num prompts */
if (buffer_add_u32(msg->session->out_buffer, ntohl(num_prompts)) < 0) {
return SSH_ERROR;
}
for(i = 0; i < num_prompts; i++) {
/* prompt[i] */
tmp = ssh_string_from_char(prompts[i]);
if (tmp == NULL) {
return SSH_ERROR;
}
r = buffer_add_ssh_string(msg->session->out_buffer, tmp);
ssh_string_free(tmp);
if (r < 0) {
return SSH_ERROR;
}
/* echo[i] */
if (buffer_add_u8(msg->session->out_buffer, echo[i]) < 0) {
return SSH_ERROR;
}
}
r = packet_send(msg->session);
/* fill in the kbdint structure */
if (msg->session->kbdint == NULL) {
SSH_LOG(SSH_LOG_PROTOCOL, "Warning: Got a "
"keyboard-interactive response but it "
"seems we didn't send the request.");
msg->session->kbdint = ssh_kbdint_new();
if (msg->session->kbdint == NULL) {
ssh_set_error_oom(msg->session);
return SSH_ERROR;
}
} else {
ssh_kbdint_clean(msg->session->kbdint);
}
msg->session->kbdint->name = strdup(name);
if(msg->session->kbdint->name == NULL) {
ssh_set_error_oom(msg->session);
ssh_kbdint_free(msg->session->kbdint);
msg->session->kbdint = NULL;
return SSH_PACKET_USED;
}
msg->session->kbdint->instruction = strdup(instruction);
if(msg->session->kbdint->instruction == NULL) {
ssh_set_error_oom(msg->session);
ssh_kbdint_free(msg->session->kbdint);
msg->session->kbdint = NULL;
return SSH_PACKET_USED;
}
msg->session->kbdint->nprompts = num_prompts;
if(num_prompts > 0) {
msg->session->kbdint->prompts = malloc(num_prompts * sizeof(char *));
if (msg->session->kbdint->prompts == NULL) {
msg->session->kbdint->nprompts = 0;
ssh_set_error_oom(msg->session);
ssh_kbdint_free(msg->session->kbdint);
msg->session->kbdint = NULL;
return SSH_ERROR;
}
msg->session->kbdint->echo = malloc(num_prompts * sizeof(unsigned char));
if (msg->session->kbdint->echo == NULL) {
ssh_set_error_oom(msg->session);
ssh_kbdint_free(msg->session->kbdint);
msg->session->kbdint = NULL;
return SSH_ERROR;
}
for (i = 0; i < num_prompts; i++) {
msg->session->kbdint->echo[i] = echo[i];
msg->session->kbdint->prompts[i] = strdup(prompts[i]);
if (msg->session->kbdint->prompts[i] == NULL) {
ssh_set_error_oom(msg->session);
msg->session->kbdint->nprompts = i;
ssh_kbdint_free(msg->session->kbdint);
msg->session->kbdint = NULL;
return SSH_PACKET_USED;
}
}
} else {
msg->session->kbdint->prompts = NULL;
msg->session->kbdint->echo = NULL;
}
return r;
}
int ssh_auth_reply_success(ssh_session session, int partial) {
int r;
if (session == NULL) {
return SSH_ERROR;
}
if (partial) {
return ssh_auth_reply_default(session, partial);
}
session->session_state = SSH_SESSION_STATE_AUTHENTICATED;
session->flags |= SSH_SESSION_FLAG_AUTHENTICATED;
if (buffer_add_u8(session->out_buffer,SSH2_MSG_USERAUTH_SUCCESS) < 0) {
return SSH_ERROR;
}
r = packet_send(session);
if(session->current_crypto && session->current_crypto->delayed_compress_out){
SSH_LOG(SSH_LOG_PROTOCOL,"Enabling delayed compression OUT");
session->current_crypto->do_compress_out=1;
}
if(session->current_crypto && session->current_crypto->delayed_compress_in){
SSH_LOG(SSH_LOG_PROTOCOL,"Enabling delayed compression IN");
session->current_crypto->do_compress_in=1;
}
return r;
}
int ssh_message_auth_reply_success(ssh_message msg, int partial) {
if(msg == NULL)
return SSH_ERROR;
return ssh_auth_reply_success(msg->session, partial);
}
/* Answer OK to a pubkey auth request */
int ssh_message_auth_reply_pk_ok(ssh_message msg, ssh_string algo, ssh_string pubkey) {
if (msg == NULL) {
return SSH_ERROR;
}
if (buffer_add_u8(msg->session->out_buffer, SSH2_MSG_USERAUTH_PK_OK) < 0 ||
buffer_add_ssh_string(msg->session->out_buffer, algo) < 0 ||
buffer_add_ssh_string(msg->session->out_buffer, pubkey) < 0) {
return SSH_ERROR;
}
return packet_send(msg->session);
}
int ssh_message_auth_reply_pk_ok_simple(ssh_message msg) {
ssh_string algo;
ssh_string pubkey_blob = NULL;
int ret;
algo = ssh_string_from_char(msg->auth_request.pubkey->type_c);
if (algo == NULL) {
return SSH_ERROR;
}
ret = ssh_pki_export_pubkey_blob(msg->auth_request.pubkey, &pubkey_blob);
if (ret < 0) {
ssh_string_free(algo);
return SSH_ERROR;
}
ret = ssh_message_auth_reply_pk_ok(msg, algo, pubkey_blob);
ssh_string_free(algo);
ssh_string_free(pubkey_blob);
return ret;
}
const char *ssh_message_channel_request_open_originator(ssh_message msg){
return msg->channel_request_open.originator;
}
int ssh_message_channel_request_open_originator_port(ssh_message msg){
return msg->channel_request_open.originator_port;
}
const char *ssh_message_channel_request_open_destination(ssh_message msg){
return msg->channel_request_open.destination;
}
int ssh_message_channel_request_open_destination_port(ssh_message msg){
return msg->channel_request_open.destination_port;
}
ssh_channel ssh_message_channel_request_channel(ssh_message msg){
return msg->channel_request.channel;
}
const char *ssh_message_channel_request_pty_term(ssh_message msg){
return msg->channel_request.TERM;
}
int ssh_message_channel_request_pty_width(ssh_message msg){
return msg->channel_request.width;
}
int ssh_message_channel_request_pty_height(ssh_message msg){
return msg->channel_request.height;
}
int ssh_message_channel_request_pty_pxwidth(ssh_message msg){
return msg->channel_request.pxwidth;
}
int ssh_message_channel_request_pty_pxheight(ssh_message msg){
return msg->channel_request.pxheight;
}
const char *ssh_message_channel_request_env_name(ssh_message msg){
return msg->channel_request.var_name;
}
const char *ssh_message_channel_request_env_value(ssh_message msg){
return msg->channel_request.var_value;
}
const char *ssh_message_channel_request_command(ssh_message msg){
return msg->channel_request.command;
}
const char *ssh_message_channel_request_subsystem(ssh_message msg){
return msg->channel_request.subsystem;
}
int ssh_message_channel_request_x11_single_connection(ssh_message msg){
return msg->channel_request.x11_single_connection ? 1 : 0;
}
const char *ssh_message_channel_request_x11_auth_protocol(ssh_message msg){
return msg->channel_request.x11_auth_protocol;
}
const char *ssh_message_channel_request_x11_auth_cookie(ssh_message msg){
return msg->channel_request.x11_auth_cookie;
}
int ssh_message_channel_request_x11_screen_number(ssh_message msg){
return msg->channel_request.x11_screen_number;
}
const char *ssh_message_global_request_address(ssh_message msg){
return msg->global_request.bind_address;
}
int ssh_message_global_request_port(ssh_message msg){
return msg->global_request.bind_port;
}
/** @brief defines the ssh_message callback
* @param session the current ssh session
* @param[in] ssh_bind_message_callback a function pointer to a callback taking the
* current ssh session and received message as parameters. the function returns
* 0 if the message has been parsed and treated successfully, 1 otherwise (libssh
* must take care of the response).
* @param[in] data void pointer to be passed to callback functions
*/
void ssh_set_message_callback(ssh_session session,
int(*ssh_bind_message_callback)(ssh_session session, ssh_message msg, void *data),
void *data) {
session->ssh_message_callback = ssh_bind_message_callback;
session->ssh_message_callback_data = data;
}
int ssh_execute_message_callbacks(ssh_session session){
ssh_message msg=NULL;
int ret;
ssh_handle_packets(session, SSH_TIMEOUT_NONBLOCKING);
if(!session->ssh_message_list)
return SSH_OK;
if(session->ssh_message_callback){
while((msg=ssh_message_pop_head(session)) != NULL) {
ret=session->ssh_message_callback(session,msg,
session->ssh_message_callback_data);
if(ret==1){
ret = ssh_message_reply_default(msg);
ssh_message_free(msg);
if(ret != SSH_OK)
return ret;
} else {
ssh_message_free(msg);
}
}
} else {
while((msg=ssh_message_pop_head(session)) != NULL) {
ret = ssh_message_reply_default(msg);
ssh_message_free(msg);
if(ret != SSH_OK)
return ret;
}
}
return SSH_OK;
}
int ssh_send_keepalive(ssh_session session)
{
struct ssh_string_struct *req;
int rc;
rc = buffer_add_u8(session->out_buffer, SSH2_MSG_GLOBAL_REQUEST);
if (rc < 0) {
goto err;
}
req = ssh_string_from_char("keepalive@openssh.com");
if (req == NULL) {
goto err;
}
rc = buffer_add_ssh_string(session->out_buffer, req);
ssh_string_free(req);
if (rc < 0) {
goto err;
}
rc = buffer_add_u8(session->out_buffer, 1);
if (rc < 0) {
goto err;
}
if (packet_send(session) == SSH_ERROR) {
goto err;
}
ssh_handle_packets(session, 0);
SSH_LOG(SSH_LOG_PACKET, "Sent a keepalive");
return SSH_OK;
err:
ssh_set_error_oom(session);
ssh_buffer_reinit(session->out_buffer);
return SSH_ERROR;
}
/** @} */
/* vim: set ts=4 sw=4 et cindent: */
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