shinys000114/libssh
1
0
Fork 0
mirror of https://git.libssh.org/projects/libssh.git synced 2026-02-04 20:30:38 +09:00
Code Issues Packages Projects Releases Wiki Activity
Files
b815ca08b378eb923e0522350f99179dbedc2437
libssh/src/session.c
Diego Roux 46a28cfc49 log: fixes legacy fallback for multiple sessions. 
Legacy code in 'ssh_set_callbacks' will fallback to
'ssh_legacy_log_callback' (if the current log cb is
NULL) setting the user data to the current session.

However, if any other session is created afterwards,
it won't update the user data with the new session,
potentially leading to a use-after-free.

Fixes #238.

Signed-off-by: Diego Roux <diegoroux04@protonmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
2024-04-29 08:42:26 +02:00

1331 lines
35 KiB
C
Raw Blame History

/*
* session.c - non-networking functions
*
* This file is part of the SSH Library
*
* Copyright (c) 2005-2013 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 <string.h>
#include <stdlib.h>
#include "libssh/priv.h"
#include "libssh/libssh.h"
#include "libssh/crypto.h"
#include "libssh/server.h"
#include "libssh/socket.h"
#include "libssh/ssh2.h"
#include "libssh/agent.h"
#include "libssh/packet.h"
#include "libssh/session.h"
#include "libssh/misc.h"
#include "libssh/buffer.h"
#include "libssh/poll.h"
#include "libssh/pki.h"
#define FIRST_CHANNEL 42 // why not ? it helps to find bugs.
/**
* @defgroup libssh_session The SSH session functions
* @ingroup libssh
*
* Functions that manage a session.
*
* @{
*/
/**
* @brief Create a new ssh session.
*
* @returns A new ssh_session pointer, NULL on error.
*/
ssh_session ssh_new(void)
{
ssh_session session;
char *id = NULL;
int rc;
session = calloc(1, sizeof (struct ssh_session_struct));
if (session == NULL) {
return NULL;
}
session->next_crypto = crypto_new();
if (session->next_crypto == NULL) {
goto err;
}
session->socket = ssh_socket_new(session);
if (session->socket == NULL) {
goto err;
}
session->out_buffer = ssh_buffer_new();
if (session->out_buffer == NULL) {
goto err;
}
session->in_buffer = ssh_buffer_new();
if (session->in_buffer == NULL) {
goto err;
}
session->out_queue = ssh_list_new();
if (session->out_queue == NULL) {
goto err;
}
session->alive = 0;
session->auth.supported_methods = 0;
ssh_set_blocking(session, 1);
session->maxchannel = FIRST_CHANNEL;
session->agent = ssh_agent_new(session);
if (session->agent == NULL) {
goto err;
}
/* OPTIONS */
session->opts.StrictHostKeyChecking = 1;
session->opts.port = 22;
session->opts.fd = -1;
session->opts.compressionlevel = 7;
session->opts.nodelay = 0;
session->opts.identities_only = false;
session->opts.control_master = SSH_CONTROL_MASTER_NO;
session->opts.flags = SSH_OPT_FLAG_PASSWORD_AUTH |
SSH_OPT_FLAG_PUBKEY_AUTH |
SSH_OPT_FLAG_KBDINT_AUTH |
SSH_OPT_FLAG_GSSAPI_AUTH;
session->opts.exp_flags = 0;
session->opts.identity = ssh_list_new();
if (session->opts.identity == NULL) {
goto err;
}
session->opts.identity_non_exp = ssh_list_new();
if (session->opts.identity_non_exp == NULL) {
goto err;
}
session->opts.certificate = ssh_list_new();
if (session->opts.certificate == NULL) {
goto err;
}
session->opts.certificate_non_exp = ssh_list_new();
if (session->opts.certificate_non_exp == NULL) {
goto err;
}
/* the default certificates are loaded automatically from the default
* identities later */
id = strdup("%d/id_ed25519");
if (id == NULL) {
goto err;
}
rc = ssh_list_append(session->opts.identity_non_exp, id);
if (rc == SSH_ERROR) {
goto err;
}
#ifdef HAVE_ECC
id = strdup("%d/id_ecdsa");
if (id == NULL) {
goto err;
}
rc = ssh_list_append(session->opts.identity_non_exp, id);
if (rc == SSH_ERROR) {
goto err;
}
#endif
id = strdup("%d/id_rsa");
if (id == NULL) {
goto err;
}
rc = ssh_list_append(session->opts.identity_non_exp, id);
if (rc == SSH_ERROR) {
goto err;
}
/* Explicitly initialize states */
session->session_state = SSH_SESSION_STATE_NONE;
session->pending_call_state = SSH_PENDING_CALL_NONE;
session->packet_state = PACKET_STATE_INIT;
session->dh_handshake_state = DH_STATE_INIT;
session->global_req_state = SSH_CHANNEL_REQ_STATE_NONE;
session->auth.state = SSH_AUTH_STATE_NONE;
session->auth.service_state = SSH_AUTH_SERVICE_NONE;
return session;
err:
free(id);
ssh_free(session);
return NULL;
}
/**
* @brief Deallocate a SSH session handle.
*
* @param[in] session The SSH session to free.
*
* @see ssh_disconnect()
* @see ssh_new()
*/
void ssh_free(ssh_session session)
{
int i;
struct ssh_iterator *it = NULL;
struct ssh_buffer_struct *b = NULL;
if (session == NULL) {
return;
}
/*
* Delete all channels
*
* This needs the first thing we clean up cause if there is still an open
* channel we call ssh_channel_close() first. So we need a working socket
* and poll context for it.
*/
for (it = ssh_list_get_iterator(session->channels);
it != NULL;
it = ssh_list_get_iterator(session->channels)) {
ssh_channel_do_free(ssh_iterator_value(ssh_channel,it));
ssh_list_remove(session->channels, it);
}
ssh_list_free(session->channels);
session->channels = NULL;
#ifdef WITH_PCAP
if (session->pcap_ctx) {
ssh_pcap_context_free(session->pcap_ctx);
session->pcap_ctx = NULL;
}
#endif
ssh_socket_free(session->socket);
session->socket = NULL;
if (session->default_poll_ctx) {
ssh_poll_ctx_free(session->default_poll_ctx);
}
SSH_BUFFER_FREE(session->in_buffer);
SSH_BUFFER_FREE(session->out_buffer);
session->in_buffer = session->out_buffer = NULL;
if (session->in_hashbuf != NULL) {
SSH_BUFFER_FREE(session->in_hashbuf);
}
if (session->out_hashbuf != NULL) {
SSH_BUFFER_FREE(session->out_hashbuf);
}
crypto_free(session->current_crypto);
crypto_free(session->next_crypto);
ssh_agent_free(session->agent);
ssh_key_free(session->srv.rsa_key);
session->srv.rsa_key = NULL;
ssh_key_free(session->srv.ecdsa_key);
session->srv.ecdsa_key = NULL;
ssh_key_free(session->srv.ed25519_key);
session->srv.ed25519_key = NULL;
if (session->ssh_message_list) {
ssh_message msg;
for (msg = ssh_list_pop_head(ssh_message, session->ssh_message_list);
msg != NULL;
msg = ssh_list_pop_head(ssh_message, session->ssh_message_list)) {
ssh_message_free(msg);
}
ssh_list_free(session->ssh_message_list);
}
if (session->kbdint != NULL) {
ssh_kbdint_free(session->kbdint);
}
if (session->packet_callbacks) {
ssh_list_free(session->packet_callbacks);
}
/* options */
if (session->opts.identity) {
char *id;
for (id = ssh_list_pop_head(char *, session->opts.identity);
id != NULL;
id = ssh_list_pop_head(char *, session->opts.identity)) {
SAFE_FREE(id);
}
ssh_list_free(session->opts.identity);
}
if (session->opts.identity_non_exp) {
char *id;
for (id = ssh_list_pop_head(char *, session->opts.identity_non_exp);
id != NULL;
id = ssh_list_pop_head(char *, session->opts.identity_non_exp)) {
SAFE_FREE(id);
}
ssh_list_free(session->opts.identity_non_exp);
}
if (session->opts.certificate) {
char *cert = NULL;
for (cert = ssh_list_pop_head(char *, session->opts.certificate);
cert != NULL;
cert = ssh_list_pop_head(char *, session->opts.certificate)) {
SAFE_FREE(cert);
}
ssh_list_free(session->opts.certificate);
}
if (session->opts.certificate_non_exp) {
char *cert = NULL;
for (cert = ssh_list_pop_head(char *, session->opts.certificate_non_exp);
cert != NULL;
cert = ssh_list_pop_head(char *, session->opts.certificate_non_exp)) {
SAFE_FREE(cert);
}
ssh_list_free(session->opts.certificate_non_exp);
}
while ((b = ssh_list_pop_head(struct ssh_buffer_struct *,
session->out_queue)) != NULL) {
SSH_BUFFER_FREE(b);
}
ssh_list_free(session->out_queue);
ssh_agent_state_free(session->agent_state);
session->agent_state = NULL;
SAFE_FREE(session->auth.auto_state);
SAFE_FREE(session->serverbanner);
SAFE_FREE(session->clientbanner);
SAFE_FREE(session->banner);
SAFE_FREE(session->disconnect_message);
SAFE_FREE(session->peer_discon_msg);
SAFE_FREE(session->opts.agent_socket);
SAFE_FREE(session->opts.bindaddr);
SAFE_FREE(session->opts.custombanner);
SAFE_FREE(session->opts.moduli_file);
SAFE_FREE(session->opts.username);
SAFE_FREE(session->opts.host);
SAFE_FREE(session->opts.sshdir);
SAFE_FREE(session->opts.knownhosts);
SAFE_FREE(session->opts.global_knownhosts);
SAFE_FREE(session->opts.ProxyCommand);
SAFE_FREE(session->opts.gss_server_identity);
SAFE_FREE(session->opts.gss_client_identity);
SAFE_FREE(session->opts.pubkey_accepted_types);
SAFE_FREE(session->opts.control_path);
for (i = 0; i < SSH_KEX_METHODS; i++) {
if (session->opts.wanted_methods[i]) {
SAFE_FREE(session->opts.wanted_methods[i]);
}
}
_ssh_remove_legacy_log_cb();
/* burn connection, it could contain sensitive data */
explicit_bzero(session, sizeof(struct ssh_session_struct));
SAFE_FREE(session);
}
/**
* @brief get the client banner
*
* @param[in] session The SSH session
*
* @return Returns the client banner string or NULL.
*/
const char* ssh_get_clientbanner(ssh_session session) {
if (session == NULL) {
return NULL;
}
return session->clientbanner;
}
/**
* @brief get the server banner
*
* @param[in] session The SSH session
*
* @return Returns the server banner string or NULL.
*/
const char* ssh_get_serverbanner(ssh_session session) {
if(!session) {
return NULL;
}
return session->serverbanner;
}
/**
* @brief get the name of the current key exchange algorithm.
*
* @param[in] session The SSH session
*
* @return Returns the key exchange algorithm string or NULL.
*/
const char* ssh_get_kex_algo(ssh_session session) {
if ((session == NULL) ||
(session->current_crypto == NULL)) {
return NULL;
}
switch (session->current_crypto->kex_type) {
case SSH_KEX_DH_GROUP1_SHA1:
return "diffie-hellman-group1-sha1";
case SSH_KEX_DH_GROUP14_SHA1:
return "diffie-hellman-group14-sha1";
case SSH_KEX_DH_GROUP14_SHA256:
return "diffie-hellman-group14-sha256";
case SSH_KEX_DH_GROUP16_SHA512:
return "diffie-hellman-group16-sha512";
case SSH_KEX_DH_GROUP18_SHA512:
return "diffie-hellman-group18-sha512";
case SSH_KEX_ECDH_SHA2_NISTP256:
return "ecdh-sha2-nistp256";
case SSH_KEX_ECDH_SHA2_NISTP384:
return "ecdh-sha2-nistp384";
case SSH_KEX_ECDH_SHA2_NISTP521:
return "ecdh-sha2-nistp521";
case SSH_KEX_CURVE25519_SHA256:
return "curve25519-sha256";
case SSH_KEX_CURVE25519_SHA256_LIBSSH_ORG:
return "curve25519-sha256@libssh.org";
default:
break;
}
return NULL;
}
/**
* @brief get the name of the input cipher for the given session.
*
* @param[in] session The SSH session.
*
* @return Returns cipher name or NULL.
*/
const char* ssh_get_cipher_in(ssh_session session) {
if ((session != NULL) &&
(session->current_crypto != NULL) &&
(session->current_crypto->in_cipher != NULL)) {
return session->current_crypto->in_cipher->name;
}
return NULL;
}
/**
* @brief get the name of the output cipher for the given session.
*
* @param[in] session The SSH session.
*
* @return Returns cipher name or NULL.
*/
const char* ssh_get_cipher_out(ssh_session session) {
if ((session != NULL) &&
(session->current_crypto != NULL) &&
(session->current_crypto->out_cipher != NULL)) {
return session->current_crypto->out_cipher->name;
}
return NULL;
}
/**
* @brief get the name of the input HMAC algorithm for the given session.
*
* @param[in] session The SSH session.
*
* @return Returns HMAC algorithm name or NULL if unknown.
*/
const char* ssh_get_hmac_in(ssh_session session) {
if ((session != NULL) &&
(session->current_crypto != NULL)) {
return ssh_hmac_type_to_string(session->current_crypto->in_hmac, session->current_crypto->in_hmac_etm);
}
return NULL;
}
/**
* @brief get the name of the output HMAC algorithm for the given session.
*
* @param[in] session The SSH session.
*
* @return Returns HMAC algorithm name or NULL if unknown.
*/
const char* ssh_get_hmac_out(ssh_session session) {
if ((session != NULL) &&
(session->current_crypto != NULL)) {
return ssh_hmac_type_to_string(session->current_crypto->out_hmac, session->current_crypto->out_hmac_etm);
}
return NULL;
}
/**
* @internal
* @brief Close the connection socket if it is a socket created by us.
* Does not close the sockets provided by the user through options API.
*/
void
ssh_session_socket_close(ssh_session session)
{
if (session->opts.fd == SSH_INVALID_SOCKET) {
ssh_socket_close(session->socket);
}
session->alive = 0;
session->session_state = SSH_SESSION_STATE_ERROR;
}
/**
* @brief Disconnect impolitely from a remote host by closing the socket.
*
* Suitable if you forked and want to destroy this session.
*
* @param[in] session The SSH session to disconnect.
*/
void
ssh_silent_disconnect(ssh_session session)
{
if (session == NULL) {
return;
}
ssh_session_socket_close(session);
ssh_disconnect(session);
}
/**
* @brief Set the session in blocking/nonblocking mode.
*
* @param[in] session The ssh session to change.
*
* @param[in] blocking Zero for nonblocking mode.
*/
void ssh_set_blocking(ssh_session session, int blocking)
{
if (session == NULL) {
return;
}
session->flags &= ~SSH_SESSION_FLAG_BLOCKING;
session->flags |= blocking ? SSH_SESSION_FLAG_BLOCKING : 0;
}
/**
* @brief Return the blocking mode of libssh
* @param[in] session The SSH session
* @returns 0 if the session is nonblocking,
* @returns 1 if the functions may block.
*/
int ssh_is_blocking(ssh_session session)
{
return (session->flags & SSH_SESSION_FLAG_BLOCKING) ? 1 : 0;
}
/* Waits until the output socket is empty */
static int ssh_flush_termination(void *c){
ssh_session session = c;
if (ssh_socket_buffered_write_bytes(session->socket) == 0 ||
session->session_state == SSH_SESSION_STATE_ERROR)
return 1;
else
return 0;
}
/**
* @brief Blocking flush of the outgoing buffer
* @param[in] session The SSH session
* @param[in] timeout Set an upper limit on the time for which this function
* will block, in milliseconds. Specifying -1
* means an infinite timeout. This parameter is passed to
* the poll() function.
* @returns SSH_OK on success, SSH_AGAIN if timeout occurred,
* SSH_ERROR otherwise.
*/
int ssh_blocking_flush(ssh_session session, int timeout){
int rc;
if (session == NULL) {
return SSH_ERROR;
}
rc = ssh_handle_packets_termination(session, timeout,
ssh_flush_termination, session);
if (rc == SSH_ERROR) {
return rc;
}
if (!ssh_flush_termination(session)) {
rc = SSH_AGAIN;
}
return rc;
}
/**
* @brief Check if we are connected.
*
* @param[in] session The session to check if it is connected.
*
* @return 1 if we are connected, 0 if not.
*/
int ssh_is_connected(ssh_session session) {
if (session == NULL) {
return 0;
}
return session->alive;
}
/**
* @brief Get the fd of a connection.
*
* In case you'd need the file descriptor of the connection to the server/client.
*
* @param[in] session The ssh session to use.
*
* @return The file descriptor of the connection, or -1 if it is
* not connected
*/
socket_t ssh_get_fd(ssh_session session) {
if (session == NULL) {
return -1;
}
return ssh_socket_get_fd(session->socket);
}
/**
* @brief Tell the session it has data to read on the file descriptor without
* blocking.
*
* @param[in] session The ssh session to use.
*/
void ssh_set_fd_toread(ssh_session session) {
if (session == NULL) {
return;
}
ssh_socket_set_read_wontblock(session->socket);
}
/**
* @brief Tell the session it may write to the file descriptor without blocking.
*
* @param[in] session The ssh session to use.
*/
void ssh_set_fd_towrite(ssh_session session) {
if (session == NULL) {
return;
}
ssh_socket_set_write_wontblock(session->socket);
}
/**
* @brief Tell the session it has an exception to catch on the file descriptor.
*
* \param[in] session The ssh session to use.
*/
void ssh_set_fd_except(ssh_session session) {
if (session == NULL) {
return;
}
ssh_socket_set_except(session->socket);
}
/**
* @internal
*
* @brief Poll the current session for an event and call the appropriate
* callbacks. This function will not loop until the timeout is expired.
*
* This will block until one event happens.
*
* @param[in] session The session handle to use.
*
* @param[in] timeout Set an upper limit on the time for which this function
* will block, in milliseconds. Specifying SSH_TIMEOUT_INFINITE
* (-1) means an infinite timeout.
* Specifying SSH_TIMEOUT_USER means to use the timeout
* specified in options. 0 means poll will return immediately.
* This parameter is passed to the poll() function.
*
* @return SSH_OK on success, SSH_ERROR otherwise.
*/
int ssh_handle_packets(ssh_session session, int timeout)
{
ssh_poll_handle spoll = NULL;
ssh_poll_ctx ctx = NULL;
int tm = timeout;
int rc;
if (session == NULL || session->socket == NULL) {
return SSH_ERROR;
}
spoll = ssh_socket_get_poll_handle(session->socket);
if (spoll == NULL) {
ssh_set_error_oom(session);
return SSH_ERROR;
}
ssh_poll_add_events(spoll, POLLIN);
ctx = ssh_poll_get_ctx(spoll);
if (ctx == NULL) {
ctx = ssh_poll_get_default_ctx(session);
if (ctx == NULL) {
ssh_set_error_oom(session);
return SSH_ERROR;
}
ssh_poll_ctx_add(ctx, spoll);
}
if (timeout == SSH_TIMEOUT_USER) {
if (ssh_is_blocking(session)) {
tm = ssh_make_milliseconds(session->opts.timeout,
session->opts.timeout_usec);
} else {
tm = 0;
}
}
rc = ssh_poll_ctx_dopoll(ctx, tm);
if (rc == SSH_ERROR) {
session->session_state = SSH_SESSION_STATE_ERROR;
}
return rc;
}
/**
* @internal
*
* @brief Poll the current session for an event and call the appropriate
* callbacks.
*
* This will block until termination function returns true, or timeout expired.
*
* @param[in] session The session handle to use.
*
* @param[in] timeout Set an upper limit on the time for which this function
* will block, in milliseconds. Specifying
* SSH_TIMEOUT_INFINITE (-1) means an infinite timeout.
* Specifying SSH_TIMEOUT_USER means using the timeout
* specified in options. 0 means poll will return
* immediately.
* SSH_TIMEOUT_DEFAULT uses the session timeout if set or
* uses blocking parameters of the session.
* This parameter is passed to the poll() function.
*
* @param[in] fct Termination function to be used to determine if it is
* possible to stop polling.
* @param[in] user User parameter to be passed to fct termination function.
* @returns SSH_OK on success, SSH_AGAIN if timeout occurred,
* SSH_ERROR otherwise.
*/
int ssh_handle_packets_termination(ssh_session session,
int timeout,
ssh_termination_function fct,
void *user)
{
struct ssh_timestamp ts;
int timeout_ms = SSH_TIMEOUT_INFINITE;
int tm;
int ret = SSH_OK;
/* If a timeout has been provided, use it */
if (timeout >= 0) {
timeout_ms = timeout;
} else {
if (ssh_is_blocking(session)) {
if (timeout == SSH_TIMEOUT_USER || timeout == SSH_TIMEOUT_DEFAULT) {
if (session->opts.timeout > 0 ||
session->opts.timeout_usec > 0) {
timeout_ms =
ssh_make_milliseconds(session->opts.timeout,
session->opts.timeout_usec);
}
}
} else {
timeout_ms = SSH_TIMEOUT_NONBLOCKING;
}
}
/* avoid unnecessary syscall for the SSH_TIMEOUT_NONBLOCKING case */
if (timeout_ms != SSH_TIMEOUT_NONBLOCKING) {
ssh_timestamp_init(&ts);
}
tm = timeout_ms;
while(!fct(user)) {
ret = ssh_handle_packets(session, tm);
if (ret == SSH_ERROR) {
break;
}
if (ssh_timeout_elapsed(&ts, timeout_ms)) {
ret = fct(user) ? SSH_OK : SSH_AGAIN;
break;
}
tm = ssh_timeout_update(&ts, timeout_ms);
}
return ret;
}
/**
* @brief Get session status
*
* @param session The ssh session to use.
*
* @returns A bitmask including SSH_CLOSED, SSH_READ_PENDING, SSH_WRITE_PENDING
* or SSH_CLOSED_ERROR which respectively means the session is closed,
* has data to read on the connection socket and session was closed
* due to an error.
*/
int ssh_get_status(ssh_session session) {
int socketstate;
int r = 0;
if (session == NULL) {
return 0;
}
socketstate = ssh_socket_get_status(session->socket);
if (session->session_state == SSH_SESSION_STATE_DISCONNECTED) {
r |= SSH_CLOSED;
}
if (socketstate & SSH_READ_PENDING) {
r |= SSH_READ_PENDING;
}
if (socketstate & SSH_WRITE_PENDING) {
r |= SSH_WRITE_PENDING;
}
if ((session->session_state == SSH_SESSION_STATE_DISCONNECTED &&
(socketstate & SSH_CLOSED_ERROR)) ||
session->session_state == SSH_SESSION_STATE_ERROR) {
r |= SSH_CLOSED_ERROR;
}
return r;
}
/**
* @brief Get poll flags for an external mainloop
*
* @param session The ssh session to use.
*
* @returns A bitmask including SSH_READ_PENDING or SSH_WRITE_PENDING.
* For SSH_READ_PENDING, your invocation of poll() should include
* POLLIN. For SSH_WRITE_PENDING, your invocation of poll() should
* include POLLOUT.
*/
int ssh_get_poll_flags(ssh_session session)
{
if (session == NULL) {
return 0;
}
return ssh_socket_get_poll_flags (session->socket);
}
/**
* @brief Get the disconnect message from the server.
*
* @param[in] session The ssh session to use.
*
* @return The message sent by the server along with the
* disconnect, or NULL in which case the reason of the
* disconnect may be found with ssh_get_error.
*
* @see ssh_get_error()
*/
const char *ssh_get_disconnect_message(ssh_session session) {
if (session == NULL) {
return NULL;
}
if (session->session_state != SSH_SESSION_STATE_DISCONNECTED) {
ssh_set_error(session, SSH_REQUEST_DENIED,
"Connection not closed yet");
} else if(!session->peer_discon_msg) {
ssh_set_error(session, SSH_FATAL,
"Connection correctly closed but no disconnect message");
} else {
return session->peer_discon_msg;
}
return NULL;
}
/**
* @brief Get the protocol version of the session.
*
* @param session The ssh session to use.
*
* @return The SSH version as integer, < 0 on error.
*/
int ssh_get_version(ssh_session session) {
if (session == NULL) {
return -1;
}
return 2;
}
/**
* @internal
* @brief Callback to be called when the socket received an exception code.
* @param user is a pointer to session
*/
void ssh_socket_exception_callback(int code, int errno_code, void *user){
ssh_session session=(ssh_session)user;
SSH_LOG(SSH_LOG_RARE,"Socket exception callback: %d (%d)",code, errno_code);
session->session_state = SSH_SESSION_STATE_ERROR;
if (errno_code == 0 && code == SSH_SOCKET_EXCEPTION_EOF) {
ssh_set_error(session, SSH_FATAL, "Socket error: disconnected");
} else {
char err_msg[SSH_ERRNO_MSG_MAX] = {0};
ssh_set_error(session, SSH_FATAL, "Socket error: %s",
ssh_strerror(errno_code, err_msg, SSH_ERRNO_MSG_MAX));
}
session->ssh_connection_callback(session);
}
/**
* @brief Send a message that should be ignored
*
* @param[in] session The SSH session
* @param[in] data Data to be sent
*
* @return SSH_OK on success, SSH_ERROR otherwise.
*/
int ssh_send_ignore (ssh_session session, const char *data) {
const int type = SSH2_MSG_IGNORE;
int rc;
if (ssh_socket_is_open(session->socket)) {
rc = ssh_buffer_pack(session->out_buffer,
"bs",
type,
data);
if (rc != SSH_OK){
ssh_set_error_oom(session);
goto error;
}
ssh_packet_send(session);
ssh_handle_packets(session, 0);
}
return SSH_OK;
error:
ssh_buffer_reinit(session->out_buffer);
return SSH_ERROR;
}
/**
* @brief Send a debug message
*
* @param[in] session The SSH session
* @param[in] message Data to be sent
* @param[in] always_display Message SHOULD be displayed by the server. It
* SHOULD NOT be displayed unless debugging
* information has been explicitly requested.
*
* @return SSH_OK on success, SSH_ERROR otherwise.
*/
int ssh_send_debug (ssh_session session, const char *message, int always_display) {
int rc;
if (ssh_socket_is_open(session->socket)) {
rc = ssh_buffer_pack(session->out_buffer,
"bbsd",
SSH2_MSG_DEBUG,
always_display != 0 ? 1 : 0,
message,
0); /* empty language tag */
if (rc != SSH_OK) {
ssh_set_error_oom(session);
goto error;
}
ssh_packet_send(session);
ssh_handle_packets(session, 0);
}
return SSH_OK;
error:
ssh_buffer_reinit(session->out_buffer);
return SSH_ERROR;
}
/**
* @brief Set the session data counters.
*
* This function sets the counter structures to be used to calculate data
* which comes in and goes out through the session at different levels.
*
* @code
* struct ssh_counter_struct scounter = {
* .in_bytes = 0,
* .out_bytes = 0,
* .in_packets = 0,
* .out_packets = 0
* };
*
* struct ssh_counter_struct rcounter = {
* .in_bytes = 0,
* .out_bytes = 0,
* .in_packets = 0,
* .out_packets = 0
* };
*
* ssh_set_counters(session, &scounter, &rcounter);
* @endcode
*
* @param[in] session The SSH session.
*
* @param[in] scounter Counter for byte data handled by the session sockets.
*
* @param[in] rcounter Counter for byte and packet data handled by the session,
* prior compression and SSH overhead.
*/
void ssh_set_counters(ssh_session session, ssh_counter scounter,
ssh_counter rcounter) {
if (session != NULL) {
session->socket_counter = scounter;
session->raw_counter = rcounter;
}
}
/**
* @deprecated Use ssh_get_publickey_hash()
*/
int ssh_get_pubkey_hash(ssh_session session, unsigned char **hash)
{
ssh_key pubkey = NULL;
ssh_string pubkey_blob = NULL;
MD5CTX ctx = NULL;
unsigned char *h = NULL;
int rc;
if (session == NULL || hash == NULL) {
return SSH_ERROR;
}
/* In FIPS mode, we cannot use MD5 */
if (ssh_fips_mode()) {
ssh_set_error(session,
SSH_FATAL,
"In FIPS mode MD5 is not allowed."
"Try ssh_get_publickey_hash() with"
"SSH_PUBLICKEY_HASH_SHA256");
return SSH_ERROR;
}
*hash = NULL;
if (session->current_crypto == NULL ||
session->current_crypto->server_pubkey == NULL) {
ssh_set_error(session, SSH_FATAL, "No current cryptographic context");
return SSH_ERROR;
}
rc = ssh_get_server_publickey(session, &pubkey);
if (rc != SSH_OK) {
return SSH_ERROR;
}
rc = ssh_pki_export_pubkey_blob(pubkey, &pubkey_blob);
ssh_key_free(pubkey);
if (rc != SSH_OK) {
return SSH_ERROR;
}
h = calloc(MD5_DIGEST_LEN, sizeof(unsigned char));
if (h == NULL) {
SSH_STRING_FREE(pubkey_blob);
return SSH_ERROR;
}
ctx = md5_init();
if (ctx == NULL) {
SSH_STRING_FREE(pubkey_blob);
SAFE_FREE(h);
return SSH_ERROR;
}
rc = md5_update(ctx,
ssh_string_data(pubkey_blob),
ssh_string_len(pubkey_blob));
if (rc != SSH_OK) {
SSH_STRING_FREE(pubkey_blob);
md5_ctx_free(ctx);
SAFE_FREE(h);
return rc;
}
SSH_STRING_FREE(pubkey_blob);
rc = md5_final(h, ctx);
if (rc != SSH_OK) {
SAFE_FREE(h);
return rc;
}
*hash = h;
return MD5_DIGEST_LEN;
}
/**
* @brief Deallocate the hash obtained by ssh_get_pubkey_hash.
*
* This is required under Microsoft platform as this library might use a
* different C library than your software, hence a different heap.
*
* @param[in] hash The buffer to deallocate.
*
* @see ssh_get_pubkey_hash()
*/
void ssh_clean_pubkey_hash(unsigned char **hash)
{
SAFE_FREE(*hash);
}
/**
* @brief Get the server public key from a session.
*
* @param[in] session The session to get the key from.
*
* @param[out] key A pointer to store the allocated key. You need to free
* the key using ssh_key_free().
*
* @return SSH_OK on success, SSH_ERROR on error.
*
* @see ssh_key_free()
*/
int ssh_get_server_publickey(ssh_session session, ssh_key *key)
{
ssh_key pubkey = NULL;
if (session == NULL ||
session->current_crypto == NULL ||
session->current_crypto->server_pubkey == NULL) {
return SSH_ERROR;
}
pubkey = ssh_key_dup(session->current_crypto->server_pubkey);
if (pubkey == NULL) {
return SSH_ERROR;
}
*key = pubkey;
return SSH_OK;
}
/**
* @deprecated Use ssh_get_server_publickey()
*/
int ssh_get_publickey(ssh_session session, ssh_key *key)
{
return ssh_get_server_publickey(session, key);
}
/**
* @brief Allocates a buffer with the hash of the public key.
*
* This function allows you to get a hash of the public key. You can then
* print this hash in a human-readable form to the user so that he is able to
* verify it. Use ssh_get_hexa() or ssh_print_hash() to display it.
*
* @param[in] key The public key to create the hash for.
*
* @param[in] type The type of the hash you want.
*
* @param[out] hash A pointer to store the allocated buffer. It can be
* freed using ssh_clean_pubkey_hash().
*
* @param[in] hlen The length of the hash.
*
* @return 0 on success, -1 if an error occurred.
*
* @warning It is very important that you verify at some moment that the hash
* matches a known server. If you don't do it, cryptography won't help
* you at making things secure.
* OpenSSH uses SHA256 to print public key digests.
*
* @see ssh_session_update_known_hosts()
* @see ssh_get_hexa()
* @see ssh_print_hash()
* @see ssh_clean_pubkey_hash()
*/
int ssh_get_publickey_hash(const ssh_key key,
enum ssh_publickey_hash_type type,
unsigned char **hash,
size_t *hlen)
{
ssh_string blob;
unsigned char *h = NULL;
int rc;
rc = ssh_pki_export_pubkey_blob(key, &blob);
if (rc < 0) {
return rc;
}
switch (type) {
case SSH_PUBLICKEY_HASH_SHA1:
{
SHACTX ctx;
h = calloc(1, SHA_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = sha1_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = sha1_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
sha1_ctx_free(ctx);
goto out;
}
rc = sha1_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
*hlen = SHA_DIGEST_LEN;
}
break;
case SSH_PUBLICKEY_HASH_SHA256:
{
SHA256CTX ctx;
h = calloc(1, SHA256_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = sha256_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = sha256_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
sha256_ctx_free(ctx);
goto out;
}
rc = sha256_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
*hlen = SHA256_DIGEST_LEN;
}
break;
case SSH_PUBLICKEY_HASH_MD5:
{
MD5CTX ctx;
/* In FIPS mode, we cannot use MD5 */
if (ssh_fips_mode()) {
SSH_LOG(SSH_LOG_TRACE, "In FIPS mode MD5 is not allowed."
"Try using SSH_PUBLICKEY_HASH_SHA256");
rc = SSH_ERROR;
goto out;
}
h = calloc(1, MD5_DIGEST_LEN);
if (h == NULL) {
rc = -1;
goto out;
}
ctx = md5_init();
if (ctx == NULL) {
free(h);
rc = -1;
goto out;
}
rc = md5_update(ctx, ssh_string_data(blob), ssh_string_len(blob));
if (rc != SSH_OK) {
free(h);
md5_ctx_free(ctx);
goto out;
}
rc = md5_final(h, ctx);
if (rc != SSH_OK) {
free(h);
goto out;
}
*hlen = MD5_DIGEST_LEN;
}
break;
default:
rc = -1;
goto out;
}
*hash = h;
rc = 0;
out:
SSH_STRING_FREE(blob);
return rc;
}
/** @} */
Reference in New Issue View Git Blame Copy Permalink