RepoMirrors
/
openssh
mirror of git://anongit.mindrot.org/openssh.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
openssh/clientloop.c

2699 lines
77 KiB
C
Raw Blame History

/* $OpenBSD: clientloop.c,v 1.388 2023/03/03 02:37:58 dtucker Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* The main loop for the interactive session (client side).
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
*
* Copyright (c) 1999 Theo de Raadt. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* SSH2 support added by Markus Friedl.
* Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <sys/socket.h>
#include <ctype.h>
#include <errno.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <termios.h>
#include <pwd.h>
#include <unistd.h>
#include <limits.h>
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "packet.h"
#include "sshbuf.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
#include "sshkey.h"
#include "cipher.h"
#include "kex.h"
#include "myproposal.h"
#include "log.h"
#include "misc.h"
#include "readconf.h"
#include "clientloop.h"
#include "sshconnect.h"
#include "authfd.h"
#include "atomicio.h"
#include "sshpty.h"
#include "match.h"
#include "msg.h"
#include "ssherr.h"
#include "hostfile.h"
/* Permitted RSA signature algorithms for UpdateHostkeys proofs */
#define HOSTKEY_PROOF_RSA_ALGS "rsa-sha2-512,rsa-sha2-256"
/* import options */
extern Options options;
/* Control socket */
extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
/*
* Name of the host we are connecting to. This is the name given on the
* command line, or the Hostname specified for the user-supplied name in a
* configuration file.
*/
extern char *host;
/*
* If this field is not NULL, the ForwardAgent socket is this path and different
* instead of SSH_AUTH_SOCK.
*/
extern char *forward_agent_sock_path;
/*
* Flag to indicate that we have received a window change signal which has
* not yet been processed. This will cause a message indicating the new
* window size to be sent to the server a little later. This is volatile
* because this is updated in a signal handler.
*/
static volatile sig_atomic_t received_window_change_signal = 0;
static volatile sig_atomic_t received_signal = 0;
/* Time when backgrounded control master using ControlPersist should exit */
static time_t control_persist_exit_time = 0;
/* Common data for the client loop code. */
volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
static int last_was_cr; /* Last character was a newline. */
static int exit_status; /* Used to store the command exit status. */
static struct sshbuf *stderr_buffer; /* Used for final exit message. */
static int connection_in; /* Connection to server (input). */
static int connection_out; /* Connection to server (output). */
static int need_rekeying; /* Set to non-zero if rekeying is requested. */
static int session_closed; /* In SSH2: login session closed. */
static time_t x11_refuse_time; /* If >0, refuse x11 opens after this time. */
static time_t server_alive_time; /* Time to do server_alive_check */
static int hostkeys_update_complete;
static int session_setup_complete;
static void client_init_dispatch(struct ssh *ssh);
int session_ident = -1;
/* Track escape per proto2 channel */
struct escape_filter_ctx {
int escape_pending;
int escape_char;
};
/* Context for channel confirmation replies */
struct channel_reply_ctx {
const char *request_type;
int id;
enum confirm_action action;
};
/* Global request success/failure callbacks */
/* XXX move to struct ssh? */
struct global_confirm {
TAILQ_ENTRY(global_confirm) entry;
global_confirm_cb *cb;
void *ctx;
int ref_count;
};
TAILQ_HEAD(global_confirms, global_confirm);
static struct global_confirms global_confirms =
TAILQ_HEAD_INITIALIZER(global_confirms);
void ssh_process_session2_setup(int, int, int, struct sshbuf *);
static void quit_message(const char *fmt, ...)
__attribute__((__format__ (printf, 1, 2)));
static void
quit_message(const char *fmt, ...)
{
char *msg;
va_list args;
int r;
va_start(args, fmt);
xvasprintf(&msg, fmt, args);
va_end(args);
if ((r = sshbuf_putf(stderr_buffer, "%s\r\n", msg)) != 0)
fatal_fr(r, "sshbuf_putf");
quit_pending = 1;
}
/*
* Signal handler for the window change signal (SIGWINCH). This just sets a
* flag indicating that the window has changed.
*/
/*ARGSUSED */
static void
window_change_handler(int sig)
{
received_window_change_signal = 1;
}
/*
* Signal handler for signals that cause the program to terminate. These
* signals must be trapped to restore terminal modes.
*/
/*ARGSUSED */
static void
signal_handler(int sig)
{
received_signal = sig;
quit_pending = 1;
}
/*
* Sets control_persist_exit_time to the absolute time when the
* backgrounded control master should exit due to expiry of the
* ControlPersist timeout. Sets it to 0 if we are not a backgrounded
* control master process, or if there is no ControlPersist timeout.
*/
static void
set_control_persist_exit_time(struct ssh *ssh)
{
if (muxserver_sock == -1 || !options.control_persist
|| options.control_persist_timeout == 0) {
/* not using a ControlPersist timeout */
control_persist_exit_time = 0;
} else if (channel_still_open(ssh)) {
/* some client connections are still open */
if (control_persist_exit_time > 0)
debug2_f("cancel scheduled exit");
control_persist_exit_time = 0;
} else if (control_persist_exit_time <= 0) {
/* a client connection has recently closed */
control_persist_exit_time = monotime() +
(time_t)options.control_persist_timeout;
debug2_f("schedule exit in %d seconds",
options.control_persist_timeout);
}
/* else we are already counting down to the timeout */
}
#define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
static int
client_x11_display_valid(const char *display)
{
size_t i, dlen;
if (display == NULL)
return 0;
dlen = strlen(display);
for (i = 0; i < dlen; i++) {
if (!isalnum((u_char)display[i]) &&
strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
debug("Invalid character '%c' in DISPLAY", display[i]);
return 0;
}
}
return 1;
}
#define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
#define X11_TIMEOUT_SLACK 60
int
client_x11_get_proto(struct ssh *ssh, const char *display,
const char *xauth_path, u_int trusted, u_int timeout,
char **_proto, char **_data)
{
char *cmd, line[512], xdisplay[512];
char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
static char proto[512], data[512];
FILE *f;
int got_data = 0, generated = 0, do_unlink = 0, r;
struct stat st;
u_int now, x11_timeout_real;
*_proto = proto;
*_data = data;
proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
if (!client_x11_display_valid(display)) {
if (display != NULL)
logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
display);
return -1;
}
if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
debug("No xauth program.");
xauth_path = NULL;
}
if (xauth_path != NULL) {
/*
* Handle FamilyLocal case where $DISPLAY does
* not match an authorization entry. For this we
* just try "xauth list unix:displaynum.screennum".
* XXX: "localhost" match to determine FamilyLocal
* is not perfect.
*/
if (strncmp(display, "localhost:", 10) == 0) {
if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
display + 10)) < 0 ||
(size_t)r >= sizeof(xdisplay)) {
error_f("display name too long");
return -1;
}
display = xdisplay;
}
if (trusted == 0) {
/*
* Generate an untrusted X11 auth cookie.
*
* The authentication cookie should briefly outlive
* ssh's willingness to forward X11 connections to
* avoid nasty fail-open behaviour in the X server.
*/
mktemp_proto(xauthdir, sizeof(xauthdir));
if (mkdtemp(xauthdir) == NULL) {
error_f("mkdtemp: %s", strerror(errno));
return -1;
}
do_unlink = 1;
if ((r = snprintf(xauthfile, sizeof(xauthfile),
"%s/xauthfile", xauthdir)) < 0 ||
(size_t)r >= sizeof(xauthfile)) {
error_f("xauthfile path too long");
rmdir(xauthdir);
return -1;
}
if (timeout == 0) {
/* auth doesn't time out */
xasprintf(&cmd, "%s -f %s generate %s %s "
"untrusted 2>%s",
xauth_path, xauthfile, display,
SSH_X11_PROTO, _PATH_DEVNULL);
} else {
/* Add some slack to requested expiry */
if (timeout < UINT_MAX - X11_TIMEOUT_SLACK)
x11_timeout_real = timeout +
X11_TIMEOUT_SLACK;
else {
/* Don't overflow on long timeouts */
x11_timeout_real = UINT_MAX;
}
xasprintf(&cmd, "%s -f %s generate %s %s "
"untrusted timeout %u 2>%s",
xauth_path, xauthfile, display,
SSH_X11_PROTO, x11_timeout_real,
_PATH_DEVNULL);
}
debug2_f("xauth command: %s", cmd);
if (timeout != 0 && x11_refuse_time == 0) {
now = monotime() + 1;
if (SSH_TIME_T_MAX - timeout < now)
x11_refuse_time = SSH_TIME_T_MAX;
else
x11_refuse_time = now + timeout;
channel_set_x11_refuse_time(ssh,
x11_refuse_time);
}
if (system(cmd) == 0)
generated = 1;
free(cmd);
}
/*
* When in untrusted mode, we read the cookie only if it was
* successfully generated as an untrusted one in the step
* above.
*/
if (trusted || generated) {
xasprintf(&cmd,
"%s %s%s list %s 2>" _PATH_DEVNULL,
xauth_path,
generated ? "-f " : "" ,
generated ? xauthfile : "",
display);
debug2("x11_get_proto: %s", cmd);
f = popen(cmd, "r");
if (f && fgets(line, sizeof(line), f) &&
sscanf(line, "%*s %511s %511s", proto, data) == 2)
got_data = 1;
if (f)
pclose(f);
free(cmd);
}
}
if (do_unlink) {
unlink(xauthfile);
rmdir(xauthdir);
}
/* Don't fall back to fake X11 data for untrusted forwarding */
if (!trusted && !got_data) {
error("Warning: untrusted X11 forwarding setup failed: "
"xauth key data not generated");
return -1;
}
/*
* If we didn't get authentication data, just make up some
* data. The forwarding code will check the validity of the
* response anyway, and substitute this data. The X11
* server, however, will ignore this fake data and use
* whatever authentication mechanisms it was using otherwise
* for the local connection.
*/
if (!got_data) {
u_int8_t rnd[16];
u_int i;
logit("Warning: No xauth data; "
"using fake authentication data for X11 forwarding.");
strlcpy(proto, SSH_X11_PROTO, sizeof proto);
arc4random_buf(rnd, sizeof(rnd));
for (i = 0; i < sizeof(rnd); i++) {
snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
rnd[i]);
}
}
return 0;
}
/*
* Checks if the client window has changed, and sends a packet about it to
* the server if so. The actual change is detected elsewhere (by a software
* interrupt on Unix); this just checks the flag and sends a message if
* appropriate.
*/
static void
client_check_window_change(struct ssh *ssh)
{
if (!received_window_change_signal)
return;
received_window_change_signal = 0;
debug2_f("changed");
channel_send_window_changes(ssh);
}
static int
client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
{
struct global_confirm *gc;
if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
return 0;
if (gc->cb != NULL)
gc->cb(ssh, type, seq, gc->ctx);
if (--gc->ref_count <= 0) {
TAILQ_REMOVE(&global_confirms, gc, entry);
freezero(gc, sizeof(*gc));
}
ssh_packet_set_alive_timeouts(ssh, 0);
return 0;
}
static void
schedule_server_alive_check(void)
{
if (options.server_alive_interval > 0)
server_alive_time = monotime() + options.server_alive_interval;
}
static void
server_alive_check(struct ssh *ssh)
{
int r;
if (ssh_packet_inc_alive_timeouts(ssh) > options.server_alive_count_max) {
logit("Timeout, server %s not responding.", host);
cleanup_exit(255);
}
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 ||
(r = sshpkt_put_u8(ssh, 1)) != 0 || /* boolean: want reply */
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
/* Insert an empty placeholder to maintain ordering */
client_register_global_confirm(NULL, NULL);
schedule_server_alive_check();
}
/*
* Waits until the client can do something (some data becomes available on
* one of the file descriptors).
*/
static void
client_wait_until_can_do_something(struct ssh *ssh, struct pollfd **pfdp,
u_int *npfd_allocp, u_int *npfd_activep, int rekeying,
int *conn_in_readyp, int *conn_out_readyp)
{
struct timespec timeout;
int ret;
u_int p;
*conn_in_readyp = *conn_out_readyp = 0;
/* Prepare channel poll. First two pollfd entries are reserved */
ptimeout_init(&timeout);
channel_prepare_poll(ssh, pfdp, npfd_allocp, npfd_activep, 2, &timeout);
if (*npfd_activep < 2)
fatal_f("bad npfd %u", *npfd_activep); /* shouldn't happen */
/* channel_prepare_poll could have closed the last channel */
if (session_closed && !channel_still_open(ssh) &&
!ssh_packet_have_data_to_write(ssh)) {
/* clear events since we did not call poll() */
for (p = 0; p < *npfd_activep; p++)
(*pfdp)[p].revents = 0;
return;
}
/* Monitor server connection on reserved pollfd entries */
(*pfdp)[0].fd = connection_in;
(*pfdp)[0].events = POLLIN;
(*pfdp)[1].fd = connection_out;
(*pfdp)[1].events = ssh_packet_have_data_to_write(ssh) ? POLLOUT : 0;
/*
* Wait for something to happen. This will suspend the process until
* some polled descriptor can be read, written, or has some other
* event pending, or a timeout expires.
*/
set_control_persist_exit_time(ssh);
if (control_persist_exit_time > 0)
ptimeout_deadline_monotime(&timeout, control_persist_exit_time);
if (options.server_alive_interval > 0)
ptimeout_deadline_monotime(&timeout, server_alive_time);
if (options.rekey_interval > 0 && !rekeying) {
ptimeout_deadline_sec(&timeout,
ssh_packet_get_rekey_timeout(ssh));
}
ret = poll(*pfdp, *npfd_activep, ptimeout_get_ms(&timeout));
if (ret == -1) {
/*
* We have to clear the events because we return.
* We have to return, because the mainloop checks for the flags
* set by the signal handlers.
*/
for (p = 0; p < *npfd_activep; p++)
(*pfdp)[p].revents = 0;
if (errno == EINTR)
return;
/* Note: we might still have data in the buffers. */
quit_message("poll: %s", strerror(errno));
return;
}
*conn_in_readyp = (*pfdp)[0].revents != 0;
*conn_out_readyp = (*pfdp)[1].revents != 0;
if (options.server_alive_interval > 0 && !*conn_in_readyp &&
monotime() >= server_alive_time) {
/*
* ServerAlive check is needed. We can't rely on the poll
* timing out since traffic on the client side such as port
* forwards can keep waking it up.
*/
server_alive_check(ssh);
}
}
static void
client_suspend_self(struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr)
{
/* Flush stdout and stderr buffers. */
if (sshbuf_len(bout) > 0)
atomicio(vwrite, fileno(stdout), sshbuf_mutable_ptr(bout),
sshbuf_len(bout));
if (sshbuf_len(berr) > 0)
atomicio(vwrite, fileno(stderr), sshbuf_mutable_ptr(berr),
sshbuf_len(berr));
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
sshbuf_reset(bin);
sshbuf_reset(bout);
sshbuf_reset(berr);
/* Send the suspend signal to the program itself. */
kill(getpid(), SIGTSTP);
/* Reset window sizes in case they have changed */
received_window_change_signal = 1;
enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
}
static void
client_process_net_input(struct ssh *ssh)
{
int r;
/*
* Read input from the server, and add any such data to the buffer of
* the packet subsystem.
*/
schedule_server_alive_check();
if ((r = ssh_packet_process_read(ssh, connection_in)) == 0)
return; /* success */
if (r == SSH_ERR_SYSTEM_ERROR) {
if (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK)
return;
if (errno == EPIPE) {
quit_message("Connection to %s closed by remote host.",
host);
return;
}
}
quit_message("Read from remote host %s: %s", host, ssh_err(r));
}
static void
client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
{
struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
char errmsg[256];
int r, tochan;
/*
* If a TTY was explicitly requested, then a failure to allocate
* one is fatal.
*/
if (cr->action == CONFIRM_TTY &&
(options.request_tty == REQUEST_TTY_FORCE ||
options.request_tty == REQUEST_TTY_YES))
cr->action = CONFIRM_CLOSE;
/* XXX suppress on mux _client_ quietmode */
tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
if (type == SSH2_MSG_CHANNEL_SUCCESS) {
debug2("%s request accepted on channel %d",
cr->request_type, c->self);
} else if (type == SSH2_MSG_CHANNEL_FAILURE) {
if (tochan) {
snprintf(errmsg, sizeof(errmsg),
"%s request failed\r\n", cr->request_type);
} else {
snprintf(errmsg, sizeof(errmsg),
"%s request failed on channel %d",
cr->request_type, c->self);
}
/* If error occurred on primary session channel, then exit */
if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
fatal("%s", errmsg);
/*
* If error occurred on mux client, append to
* their stderr.
*/
if (tochan) {
debug3_f("channel %d: mux request: %s", c->self,
cr->request_type);
if ((r = sshbuf_put(c->extended, errmsg,
strlen(errmsg))) != 0)
fatal_fr(r, "sshbuf_put");
} else
error("%s", errmsg);
if (cr->action == CONFIRM_TTY) {
/*
* If a TTY allocation error occurred, then arrange
* for the correct TTY to leave raw mode.
*/
if (c->self == session_ident)
leave_raw_mode(0);
else
mux_tty_alloc_failed(ssh, c);
} else if (cr->action == CONFIRM_CLOSE) {
chan_read_failed(ssh, c);
chan_write_failed(ssh, c);
}
}
free(cr);
}
static void
client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx)
{
free(ctx);
}
void
client_expect_confirm(struct ssh *ssh, int id, const char *request,
enum confirm_action action)
{
struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
cr->request_type = request;
cr->action = action;
channel_register_status_confirm(ssh, id, client_status_confirm,
client_abandon_status_confirm, cr);
}
void
client_register_global_confirm(global_confirm_cb *cb, void *ctx)
{
struct global_confirm *gc, *last_gc;
/* Coalesce identical callbacks */
last_gc = TAILQ_LAST(&global_confirms, global_confirms);
if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
if (++last_gc->ref_count >= INT_MAX)
fatal_f("last_gc->ref_count = %d",
last_gc->ref_count);
return;
}
gc = xcalloc(1, sizeof(*gc));
gc->cb = cb;
gc->ctx = ctx;
gc->ref_count = 1;
TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
}
/*
* Returns non-zero if the client is able to handle a hostkeys-00@openssh.com
* hostkey update request.
*/
static int
can_update_hostkeys(void)
{
if (hostkeys_update_complete)
return 0;
if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
options.batch_mode)
return 0; /* won't ask in batchmode, so don't even try */
if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
return 0;
return 1;
}
static void
client_repledge(void)
{
debug3_f("enter");
/* Might be able to tighten pledge now that session is established */
if (options.control_master || options.control_path != NULL ||
options.forward_x11 || options.fork_after_authentication ||
can_update_hostkeys() ||
(session_ident != -1 && !session_setup_complete)) {
/* Can't tighten */
return;
}
/*
* LocalCommand and UpdateHostkeys have finished, so can get rid of
* filesystem.
*
* XXX protocol allows a server can to change hostkeys during the
* connection at rekey time that could trigger a hostkeys update
* but AFAIK no implementations support this. Could improve by
* forcing known_hosts to be read-only or via unveil(2).
*/
if (options.num_local_forwards != 0 ||
options.num_remote_forwards != 0 ||
options.num_permitted_remote_opens != 0 ||
options.enable_escape_commandline != 0) {
/* rfwd needs inet */
debug("pledge: network");
if (pledge("stdio unix inet dns proc tty", NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else if (options.forward_agent != 0) {
/* agent forwarding needs to open $SSH_AUTH_SOCK at will */
debug("pledge: agent");
if (pledge("stdio unix proc tty", NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else {
debug("pledge: fork");
if (pledge("stdio proc tty", NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
}
/* XXX further things to do:
*
* - might be able to get rid of proc if we kill ~^Z
* - ssh -N (no session)
* - stdio forwarding
* - sessions without tty
*/
}
static void
process_cmdline(struct ssh *ssh)
{
void (*handler)(int);
char *s, *cmd;
int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
struct Forward fwd;
memset(&fwd, 0, sizeof(fwd));
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
handler = ssh_signal(SIGINT, SIG_IGN);
cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
if (s == NULL)
goto out;
while (isspace((u_char)*s))
s++;
if (*s == '-')
s++; /* Skip cmdline '-', if any */
if (*s == '\0')
goto out;
if (*s == 'h' || *s == 'H' || *s == '?') {
logit("Commands:");
logit(" -L[bind_address:]port:host:hostport "
"Request local forward");
logit(" -R[bind_address:]port:host:hostport "
"Request remote forward");
logit(" -D[bind_address:]port "
"Request dynamic forward");
logit(" -KL[bind_address:]port "
"Cancel local forward");
logit(" -KR[bind_address:]port "
"Cancel remote forward");
logit(" -KD[bind_address:]port "
"Cancel dynamic forward");
if (!options.permit_local_command)
goto out;
logit(" !args "
"Execute local command");
goto out;
}
if (*s == '!' && options.permit_local_command) {
s++;
ssh_local_cmd(s);
goto out;
}
if (*s == 'K') {
delete = 1;
s++;
}
if (*s == 'L')
local = 1;
else if (*s == 'R')
remote = 1;
else if (*s == 'D')
dynamic = 1;
else {
logit("Invalid command.");
goto out;
}
while (isspace((u_char)*++s))
;
/* XXX update list of forwards in options */
if (delete) {
/* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
if (!parse_forward(&fwd, s, 1, 0)) {
logit("Bad forwarding close specification.");
goto out;
}
if (remote)
ok = channel_request_rforward_cancel(ssh, &fwd) == 0;
else if (dynamic)
ok = channel_cancel_lport_listener(ssh, &fwd,
0, &options.fwd_opts) > 0;
else
ok = channel_cancel_lport_listener(ssh, &fwd,
CHANNEL_CANCEL_PORT_STATIC,
&options.fwd_opts) > 0;
if (!ok) {
logit("Unknown port forwarding.");
goto out;
}
logit("Canceled forwarding.");
} else {
/* -R specs can be both dynamic or not, so check both. */
if (remote) {
if (!parse_forward(&fwd, s, 0, remote) &&
!parse_forward(&fwd, s, 1, remote)) {
logit("Bad remote forwarding specification.");
goto out;
}
} else if (!parse_forward(&fwd, s, dynamic, remote)) {
logit("Bad local forwarding specification.");
goto out;
}
if (local || dynamic) {
if (!channel_setup_local_fwd_listener(ssh, &fwd,
&options.fwd_opts)) {
logit("Port forwarding failed.");
goto out;
}
} else {
if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
logit("Port forwarding failed.");
goto out;
}
}
logit("Forwarding port.");
}
out:
ssh_signal(SIGINT, handler);
enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
free(cmd);
free(fwd.listen_host);
free(fwd.listen_path);
free(fwd.connect_host);
free(fwd.connect_path);
}
/* reasons to suppress output of an escape command in help output */
#define SUPPRESS_NEVER 0 /* never suppress, always show */
#define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */
#define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */
#define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */
#define SUPPRESS_NOCMDLINE 8 /* don't show when cmdline disabled*/
struct escape_help_text {
const char *cmd;
const char *text;
unsigned int flags;
};
static struct escape_help_text esc_txt[] = {
{".", "terminate session", SUPPRESS_MUXMASTER},
{".", "terminate connection (and any multiplexed sessions)",
SUPPRESS_MUXCLIENT},
{"B", "send a BREAK to the remote system", SUPPRESS_NEVER},
{"C", "open a command line", SUPPRESS_MUXCLIENT|SUPPRESS_NOCMDLINE},
{"R", "request rekey", SUPPRESS_NEVER},
{"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
{"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
{"#", "list forwarded connections", SUPPRESS_NEVER},
{"&", "background ssh (when waiting for connections to terminate)",
SUPPRESS_MUXCLIENT},
{"?", "this message", SUPPRESS_NEVER},
};
static void
print_escape_help(struct sshbuf *b, int escape_char, int mux_client,
int using_stderr)
{
unsigned int i, suppress_flags;
int r;
if ((r = sshbuf_putf(b,
"%c?\r\nSupported escape sequences:\r\n", escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
suppress_flags =
(mux_client ? SUPPRESS_MUXCLIENT : 0) |
(mux_client ? 0 : SUPPRESS_MUXMASTER) |
(using_stderr ? 0 : SUPPRESS_SYSLOG) |
(options.enable_escape_commandline == 0 ? SUPPRESS_NOCMDLINE : 0);
for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
if (esc_txt[i].flags & suppress_flags)
continue;
if ((r = sshbuf_putf(b, " %c%-3s - %s\r\n",
escape_char, esc_txt[i].cmd, esc_txt[i].text)) != 0)
fatal_fr(r, "sshbuf_putf");
}
if ((r = sshbuf_putf(b,
" %c%c - send the escape character by typing it twice\r\n"
"(Note that escapes are only recognized immediately after "
"newline.)\r\n", escape_char, escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
}
/*
* Process the characters one by one.
*/
static int
process_escapes(struct ssh *ssh, Channel *c,
struct sshbuf *bin, struct sshbuf *bout, struct sshbuf *berr,
char *buf, int len)
{
pid_t pid;
int r, bytes = 0;
u_int i;
u_char ch;
char *s;
struct escape_filter_ctx *efc = c->filter_ctx == NULL ?
NULL : (struct escape_filter_ctx *)c->filter_ctx;
if (c->filter_ctx == NULL)
return 0;
if (len <= 0)
return (0);
for (i = 0; i < (u_int)len; i++) {
/* Get one character at a time. */
ch = buf[i];
if (efc->escape_pending) {
/* We have previously seen an escape character. */
/* Clear the flag now. */
efc->escape_pending = 0;
/* Process the escaped character. */
switch (ch) {
case '.':
/* Terminate the connection. */
if ((r = sshbuf_putf(berr, "%c.\r\n",
efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
if (c && c->ctl_chan != -1) {
channel_force_close(ssh, c, 1);
return 0;
} else
quit_pending = 1;
return -1;
case 'Z' - 64:
/* XXX support this for mux clients */
if (c && c->ctl_chan != -1) {
char b[16];
noescape:
if (ch == 'Z' - 64)
snprintf(b, sizeof b, "^Z");
else
snprintf(b, sizeof b, "%c", ch);
if ((r = sshbuf_putf(berr,
"%c%s escape not available to "
"multiplexed sessions\r\n",
efc->escape_char, b)) != 0)
fatal_fr(r, "sshbuf_putf");
continue;
}
/* Suspend the program. Inform the user */
if ((r = sshbuf_putf(berr,
"%c^Z [suspend ssh]\r\n",
efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
/* Restore terminal modes and suspend. */
client_suspend_self(bin, bout, berr);
/* We have been continued. */
continue;
case 'B':
if ((r = sshbuf_putf(berr,
"%cB\r\n", efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
channel_request_start(ssh, c->self, "break", 0);
if ((r = sshpkt_put_u32(ssh, 1000)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send packet");
continue;
case 'R':
if (ssh->compat & SSH_BUG_NOREKEY)
logit("Server does not "
"support re-keying");
else
need_rekeying = 1;
continue;
case 'V':
/* FALLTHROUGH */
case 'v':
if (c && c->ctl_chan != -1)
goto noescape;
if (!log_is_on_stderr()) {
if ((r = sshbuf_putf(berr,
"%c%c [Logging to syslog]\r\n",
efc->escape_char, ch)) != 0)
fatal_fr(r, "sshbuf_putf");
continue;
}
if (ch == 'V' && options.log_level >
SYSLOG_LEVEL_QUIET)
log_change_level(--options.log_level);
if (ch == 'v' && options.log_level <
SYSLOG_LEVEL_DEBUG3)
log_change_level(++options.log_level);
if ((r = sshbuf_putf(berr,
"%c%c [LogLevel %s]\r\n",
efc->escape_char, ch,
log_level_name(options.log_level))) != 0)
fatal_fr(r, "sshbuf_putf");
continue;
case '&':
if (c && c->ctl_chan != -1)
goto noescape;
/*
* Detach the program (continue to serve
* connections, but put in background and no
* more new connections).
*/
/* Restore tty modes. */
leave_raw_mode(
options.request_tty == REQUEST_TTY_FORCE);
/* Stop listening for new connections. */
channel_stop_listening(ssh);
if ((r = sshbuf_putf(berr, "%c& "
"[backgrounded]\n", efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
/* Fork into background. */
pid = fork();
if (pid == -1) {
error("fork: %.100s", strerror(errno));
continue;
}
if (pid != 0) { /* This is the parent. */
/* The parent just exits. */
exit(0);
}
/* The child continues serving connections. */
/* fake EOF on stdin */
if ((r = sshbuf_put_u8(bin, 4)) != 0)
fatal_fr(r, "sshbuf_put_u8");
return -1;
case '?':
print_escape_help(berr, efc->escape_char,
(c && c->ctl_chan != -1),
log_is_on_stderr());
continue;
case '#':
if ((r = sshbuf_putf(berr, "%c#\r\n",
efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_putf");
s = channel_open_message(ssh);
if ((r = sshbuf_put(berr, s, strlen(s))) != 0)
fatal_fr(r, "sshbuf_put");
free(s);
continue;
case 'C':
if (c && c->ctl_chan != -1)
goto noescape;
if (options.enable_escape_commandline == 0) {
if ((r = sshbuf_putf(berr,
"commandline disabled\r\n")) != 0)
fatal_fr(r, "sshbuf_putf");
continue;
}
process_cmdline(ssh);
continue;
default:
if (ch != efc->escape_char) {
if ((r = sshbuf_put_u8(bin,
efc->escape_char)) != 0)
fatal_fr(r, "sshbuf_put_u8");
bytes++;
}
/* Escaped characters fall through here */
break;
}
} else {
/*
* The previous character was not an escape char.
* Check if this is an escape.
*/
if (last_was_cr && ch == efc->escape_char) {
/*
* It is. Set the flag and continue to
* next character.
*/
efc->escape_pending = 1;
continue;
}
}
/*
* Normal character. Record whether it was a newline,
* and append it to the buffer.
*/
last_was_cr = (ch == '\r' || ch == '\n');
if ((r = sshbuf_put_u8(bin, ch)) != 0)
fatal_fr(r, "sshbuf_put_u8");
bytes++;
}
return bytes;
}
/*
* Get packets from the connection input buffer, and process them as long as
* there are packets available.
*
* Any unknown packets received during the actual
* session cause the session to terminate. This is
* intended to make debugging easier since no
* confirmations are sent. Any compatible protocol
* extensions must be negotiated during the
* preparatory phase.
*/
static void
client_process_buffered_input_packets(struct ssh *ssh)
{
ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, &quit_pending);
}
/* scan buf[] for '~' before sending data to the peer */
/* Helper: allocate a new escape_filter_ctx and fill in its escape char */
void *
client_new_escape_filter_ctx(int escape_char)
{
struct escape_filter_ctx *ret;
ret = xcalloc(1, sizeof(*ret));
ret->escape_pending = 0;
ret->escape_char = escape_char;
return (void *)ret;
}
/* Free the escape filter context on channel free */
void
client_filter_cleanup(struct ssh *ssh, int cid, void *ctx)
{
free(ctx);
}
int
client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len)
{
if (c->extended_usage != CHAN_EXTENDED_WRITE)
return 0;
return process_escapes(ssh, c, c->input, c->output, c->extended,
buf, len);
}
static void
client_channel_closed(struct ssh *ssh, int id, int force, void *arg)
{
channel_cancel_cleanup(ssh, id);
session_closed = 1;
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
}
/*
* Implements the interactive session with the server. This is called after
* the user has been authenticated, and a command has been started on the
* remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character
* used as an escape character for terminating or suspending the session.
*/
int
client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
int ssh2_chan_id)
{
struct pollfd *pfd = NULL;
u_int npfd_alloc = 0, npfd_active = 0;
double start_time, total_time;
int r, len;
u_int64_t ibytes, obytes;
int conn_in_ready, conn_out_ready;
debug("Entering interactive session.");
session_ident = ssh2_chan_id;
if (options.control_master &&
!option_clear_or_none(options.control_path)) {
debug("pledge: id");
if (pledge("stdio rpath wpath cpath unix inet dns recvfd sendfd proc exec id tty",
NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else if (options.forward_x11 || options.permit_local_command) {
debug("pledge: exec");
if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else if (options.update_hostkeys) {
debug("pledge: filesystem");
if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else if (!option_clear_or_none(options.proxy_command) ||
options.fork_after_authentication) {
debug("pledge: proc");
if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
} else {
debug("pledge: network");
if (pledge("stdio unix inet dns proc tty", NULL) == -1)
fatal_f("pledge(): %s", strerror(errno));
}
/* might be able to tighten now */
client_repledge();
start_time = monotime_double();
/* Initialize variables. */
last_was_cr = 1;
exit_status = -1;
connection_in = ssh_packet_get_connection_in(ssh);
connection_out = ssh_packet_get_connection_out(ssh);
quit_pending = 0;
/* Initialize buffer. */
if ((stderr_buffer = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
client_init_dispatch(ssh);
/*
* Set signal handlers, (e.g. to restore non-blocking mode)
* but don't overwrite SIG_IGN, matches behaviour from rsh(1)
*/
if (ssh_signal(SIGHUP, SIG_IGN) != SIG_IGN)
ssh_signal(SIGHUP, signal_handler);
if (ssh_signal(SIGINT, SIG_IGN) != SIG_IGN)
ssh_signal(SIGINT, signal_handler);
if (ssh_signal(SIGQUIT, SIG_IGN) != SIG_IGN)
ssh_signal(SIGQUIT, signal_handler);
if (ssh_signal(SIGTERM, SIG_IGN) != SIG_IGN)
ssh_signal(SIGTERM, signal_handler);
ssh_signal(SIGWINCH, window_change_handler);
if (have_pty)
enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
if (session_ident != -1) {
if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
channel_register_filter(ssh, session_ident,
client_simple_escape_filter, NULL,
client_filter_cleanup,
client_new_escape_filter_ctx(
escape_char_arg));
}
channel_register_cleanup(ssh, session_ident,
client_channel_closed, 0);
}
schedule_server_alive_check();
/* Main loop of the client for the interactive session mode. */
while (!quit_pending) {
/* Process buffered packets sent by the server. */
client_process_buffered_input_packets(ssh);
if (session_closed && !channel_still_open(ssh))
break;
if (ssh_packet_is_rekeying(ssh)) {
debug("rekeying in progress");
} else if (need_rekeying) {
/* manual rekey request */
debug("need rekeying");
if ((r = kex_start_rekex(ssh)) != 0)
fatal_fr(r, "kex_start_rekex");
need_rekeying = 0;
} else {
/*
* Make packets from buffered channel data, and
* enqueue them for sending to the server.
*/
if (ssh_packet_not_very_much_data_to_write(ssh))
channel_output_poll(ssh);
/*
* Check if the window size has changed, and buffer a
* message about it to the server if so.
*/
client_check_window_change(ssh);
if (quit_pending)
break;
}
/*
* Wait until we have something to do (something becomes
* available on one of the descriptors).
*/
client_wait_until_can_do_something(ssh, &pfd, &npfd_alloc,
&npfd_active, ssh_packet_is_rekeying(ssh),
&conn_in_ready, &conn_out_ready);
if (quit_pending)
break;
/* Do channel operations. */
channel_after_poll(ssh, pfd, npfd_active);
/* Buffer input from the connection. */
if (conn_in_ready)
client_process_net_input(ssh);
if (quit_pending)
break;
/* A timeout may have triggered rekeying */
if ((r = ssh_packet_check_rekey(ssh)) != 0)
fatal_fr(r, "cannot start rekeying");
/*
* Send as much buffered packet data as possible to the
* sender.
*/
if (conn_out_ready) {
if ((r = ssh_packet_write_poll(ssh)) != 0) {
sshpkt_fatal(ssh, r,
"%s: ssh_packet_write_poll", __func__);
}
}
/*
* If we are a backgrounded control master, and the
* timeout has expired without any active client
* connections, then quit.
*/
if (control_persist_exit_time > 0) {
if (monotime() >= control_persist_exit_time) {
debug("ControlPersist timeout expired");
break;
}
}
}
free(pfd);
/* Terminate the session. */
/* Stop watching for window change. */
ssh_signal(SIGWINCH, SIG_DFL);
if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
(r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_BY_APPLICATION)) != 0 ||
(r = sshpkt_put_cstring(ssh, "disconnected by user")) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 || /* language tag */
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal_fr(r, "send disconnect");
channel_free_all(ssh);
if (have_pty)
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
/*
* If there was no shell or command requested, there will be no remote
* exit status to be returned. In that case, clear error code if the
* connection was deliberately terminated at this end.
*/
if (options.session_type == SESSION_TYPE_NONE &&
received_signal == SIGTERM) {
received_signal = 0;
exit_status = 0;
}
if (received_signal) {
verbose("Killed by signal %d.", (int) received_signal);
cleanup_exit(255);
}
/*
* In interactive mode (with pseudo tty) display a message indicating
* that the connection has been closed.
*/
if (have_pty && options.log_level >= SYSLOG_LEVEL_INFO)
quit_message("Connection to %s closed.", host);
/* Output any buffered data for stderr. */
if (sshbuf_len(stderr_buffer) > 0) {
len = atomicio(vwrite, fileno(stderr),
(u_char *)sshbuf_ptr(stderr_buffer),
sshbuf_len(stderr_buffer));
if (len < 0 || (u_int)len != sshbuf_len(stderr_buffer))
error("Write failed flushing stderr buffer.");
else if ((r = sshbuf_consume(stderr_buffer, len)) != 0)
fatal_fr(r, "sshbuf_consume");
}
/* Clear and free any buffers. */
sshbuf_free(stderr_buffer);
/* Report bytes transferred, and transfer rates. */
total_time = monotime_double() - start_time;
ssh_packet_get_bytes(ssh, &ibytes, &obytes);
verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
(unsigned long long)obytes, (unsigned long long)ibytes, total_time);
if (total_time > 0)
verbose("Bytes per second: sent %.1f, received %.1f",
obytes / total_time, ibytes / total_time);
/* Return the exit status of the program. */
debug("Exit status %d", exit_status);
return exit_status;
}
/*********/
static Channel *
client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
int rchan, u_int rwindow, u_int rmaxpack)
{
Channel *c = NULL;
struct sshbuf *b = NULL;
char *listen_address, *originator_address;
u_int listen_port, originator_port;
int r;
/* Get rest of the packet */
if ((r = sshpkt_get_cstring(ssh, &listen_address, NULL)) != 0 ||
(r = sshpkt_get_u32(ssh, &listen_port)) != 0 ||
(r = sshpkt_get_cstring(ssh, &originator_address, NULL)) != 0 ||
(r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal_fr(r, "parse packet");
debug_f("listen %s port %d, originator %s port %d",
listen_address, listen_port, originator_address, originator_port);
if (listen_port > 0xffff)
error_f("invalid listen port");
else if (originator_port > 0xffff)
error_f("invalid originator port");
else {
c = channel_connect_by_listen_address(ssh,
listen_address, listen_port, "forwarded-tcpip",
originator_address);
}
if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
if ((b = sshbuf_new()) == NULL) {
error_f("alloc reply");
goto out;
}
/* reconstruct and send to muxclient */
if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
(r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
(r = sshbuf_put_cstring(b, request_type)) != 0 ||
(r = sshbuf_put_u32(b, rchan)) != 0 ||
(r = sshbuf_put_u32(b, rwindow)) != 0 ||
(r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
(r = sshbuf_put_cstring(b, listen_address)) != 0 ||
(r = sshbuf_put_u32(b, listen_port)) != 0 ||
(r = sshbuf_put_cstring(b, originator_address)) != 0 ||
(r = sshbuf_put_u32(b, originator_port)) != 0 ||
(r = sshbuf_put_stringb(c->output, b)) != 0) {
error_fr(r, "compose for muxclient");
goto out;
}
}
out:
sshbuf_free(b);
free(originator_address);
free(listen_address);
return c;
}
static Channel *
client_request_forwarded_streamlocal(struct ssh *ssh,
const char *request_type, int rchan)
{
Channel *c = NULL;
char *listen_path;
int r;
/* Get the remote path. */
if ((r = sshpkt_get_cstring(ssh, &listen_path, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, NULL, NULL)) != 0 || /* reserved */
(r = sshpkt_get_end(ssh)) != 0)
fatal_fr(r, "parse packet");
debug_f("request: %s", listen_path);
c = channel_connect_by_listen_path(ssh, listen_path,
"forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
free(listen_path);
return c;
}
static Channel *
client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
{
Channel *c = NULL;
char *originator;
u_int originator_port;
int r, sock;
if (!options.forward_x11) {
error("Warning: ssh server tried X11 forwarding.");
error("Warning: this is probably a break-in attempt by a "
"malicious server.");
return NULL;
}
if (x11_refuse_time != 0 && monotime() >= x11_refuse_time) {
verbose("Rejected X11 connection after ForwardX11Timeout "
"expired");
return NULL;
}
if ((r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 ||
(r = sshpkt_get_u32(ssh, &originator_port)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal_fr(r, "parse packet");
/* XXX check permission */
/* XXX range check originator port? */
debug("client_request_x11: request from %s %u", originator,
originator_port);
free(originator);
sock = x11_connect_display(ssh);
if (sock < 0)
return NULL;
c = channel_new(ssh, "x11",
SSH_CHANNEL_X11_OPEN, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
c->force_drain = 1;
return c;
}
static Channel *
client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
{
Channel *c = NULL;
int r, sock;
if (!options.forward_agent) {
error("Warning: ssh server tried agent forwarding.");
error("Warning: this is probably a break-in attempt by a "
"malicious server.");
return NULL;
}
if (forward_agent_sock_path == NULL) {
r = ssh_get_authentication_socket(&sock);
} else {
r = ssh_get_authentication_socket_path(forward_agent_sock_path, &sock);
}
if (r != 0) {
if (r != SSH_ERR_AGENT_NOT_PRESENT)
debug_fr(r, "ssh_get_authentication_socket");
return NULL;
}
if ((r = ssh_agent_bind_hostkey(sock, ssh->kex->initial_hostkey,
ssh->kex->session_id, ssh->kex->initial_sig, 1)) == 0)
debug_f("bound agent to hostkey");
else
debug2_fr(r, "ssh_agent_bind_hostkey");
c = channel_new(ssh, "authentication agent connection",
SSH_CHANNEL_OPEN, sock, sock, -1,
CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
"authentication agent connection", 1);
c->force_drain = 1;
return c;
}
char *
client_request_tun_fwd(struct ssh *ssh, int tun_mode,
int local_tun, int remote_tun, channel_open_fn *cb, void *cbctx)
{
Channel *c;
int r, fd;
char *ifname = NULL;
if (tun_mode == SSH_TUNMODE_NO)
return 0;
debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
/* Open local tunnel device */
if ((fd = tun_open(local_tun, tun_mode, &ifname)) == -1) {
error("Tunnel device open failed.");
return NULL;
}
debug("Tunnel forwarding using interface %s", ifname);
c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
c->datagram = 1;
#if defined(SSH_TUN_FILTER)
if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
channel_register_filter(ssh, c->self, sys_tun_infilter,
sys_tun_outfilter, NULL, NULL);
#endif
if (cb != NULL)
channel_register_open_confirm(ssh, c->self, cb, cbctx);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
(r = sshpkt_put_cstring(ssh, "tun@openssh.com")) != 0 ||
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window_max)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
(r = sshpkt_put_u32(ssh, tun_mode)) != 0 ||
(r = sshpkt_put_u32(ssh, remote_tun)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: send reply", __func__);
return ifname;
}
/* XXXX move to generic input handler */
static int
client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = NULL;
char *ctype = NULL;
int r;
u_int rchan;
size_t len;
u_int rmaxpack, rwindow;
if ((r = sshpkt_get_cstring(ssh, &ctype, &len)) != 0 ||
(r = sshpkt_get_u32(ssh, &rchan)) != 0 ||
(r = sshpkt_get_u32(ssh, &rwindow)) != 0 ||
(r = sshpkt_get_u32(ssh, &rmaxpack)) != 0)
goto out;
debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
ctype, rchan, rwindow, rmaxpack);
if (strcmp(ctype, "forwarded-tcpip") == 0) {
c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
rmaxpack);
} else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
} else if (strcmp(ctype, "x11") == 0) {
c = client_request_x11(ssh, ctype, rchan);
} else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
c = client_request_agent(ssh, ctype, rchan);
}
if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
debug3("proxied to downstream: %s", ctype);
} else if (c != NULL) {
debug("confirm %s", ctype);
c->remote_id = rchan;
c->have_remote_id = 1;
c->remote_window = rwindow;
c->remote_maxpacket = rmaxpack;
if (c->type != SSH_CHANNEL_CONNECTING) {
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: send reply", __func__);
}
} else {
debug("failure %s", ctype);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
(r = sshpkt_put_u32(ssh, rchan)) != 0 ||
(r = sshpkt_put_u32(ssh, SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED)) != 0 ||
(r = sshpkt_put_cstring(ssh, "open failed")) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: send failure", __func__);
}
r = 0;
out:
free(ctype);
return r;
}
static int
client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = NULL;
char *rtype = NULL;
u_char reply;
u_int id, exitval;
int r, success = 0;
if ((r = sshpkt_get_u32(ssh, &id)) != 0)
return r;
if (id <= INT_MAX)
c = channel_lookup(ssh, id);
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
(r = sshpkt_get_u8(ssh, &reply)) != 0)
goto out;
debug("client_input_channel_req: channel %u rtype %s reply %d",
id, rtype, reply);
if (c == NULL) {
error("client_input_channel_req: channel %d: "
"unknown channel", id);
} else if (strcmp(rtype, "eow@openssh.com") == 0) {
if ((r = sshpkt_get_end(ssh)) != 0)
goto out;
chan_rcvd_eow(ssh, c);
} else if (strcmp(rtype, "exit-status") == 0) {
if ((r = sshpkt_get_u32(ssh, &exitval)) != 0)
goto out;
if (c->ctl_chan != -1) {
mux_exit_message(ssh, c, exitval);
success = 1;
} else if ((int)id == session_ident) {
/* Record exit value of local session */
success = 1;
exit_status = exitval;
} else {
/* Probably for a mux channel that has already closed */
debug_f("no sink for exit-status on channel %d",
id);
}
if ((r = sshpkt_get_end(ssh)) != 0)
goto out;
}
if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
if (!c->have_remote_id)
fatal_f("channel %d: no remote_id", c->self);
if ((r = sshpkt_start(ssh, success ?
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s: send failure", __func__);
}
r = 0;
out:
free(rtype);
return r;
}
struct hostkeys_update_ctx {
/* The hostname and (optionally) IP address string for the server */
char *host_str, *ip_str;
/*
* Keys received from the server and a flag for each indicating
* whether they already exist in known_hosts.
* keys_match is filled in by hostkeys_find() and later (for new
* keys) by client_global_hostkeys_prove_confirm().
*/
struct sshkey **keys;
u_int *keys_match; /* mask of HKF_MATCH_* from hostfile.h */
int *keys_verified; /* flag for new keys verified by server */
size_t nkeys, nnew, nincomplete; /* total, new keys, incomplete match */
/*
* Keys that are in known_hosts, but were not present in the update
* from the server (i.e. scheduled to be deleted).
* Filled in by hostkeys_find().
*/
struct sshkey **old_keys;
size_t nold;
/* Various special cases. */
int complex_hostspec; /* wildcard or manual pattern-list host name */
int ca_available; /* saw CA key for this host */
int old_key_seen; /* saw old key with other name/addr */
int other_name_seen; /* saw key with other name/addr */
};
static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
{
size_t i;
if (ctx == NULL)
return;
for (i = 0; i < ctx->nkeys; i++)
sshkey_free(ctx->keys[i]);
free(ctx->keys);
free(ctx->keys_match);
free(ctx->keys_verified);
for (i = 0; i < ctx->nold; i++)
sshkey_free(ctx->old_keys[i]);
free(ctx->old_keys);
free(ctx->host_str);
free(ctx->ip_str);
free(ctx);
}
/*
* Returns non-zero if a known_hosts hostname list is not of a form that
* can be handled by UpdateHostkeys. These include wildcard hostnames and
* hostnames lists that do not follow the form host[,ip].
*/
static int
hostspec_is_complex(const char *hosts)
{
char *cp;
/* wildcard */
if (strchr(hosts, '*') != NULL || strchr(hosts, '?') != NULL)
return 1;
/* single host/ip = ok */
if ((cp = strchr(hosts, ',')) == NULL)
return 0;
/* more than two entries on the line */
if (strchr(cp + 1, ',') != NULL)
return 1;
/* XXX maybe parse cp+1 and ensure it is an IP? */
return 0;
}
/* callback to search for ctx->keys in known_hosts */
static int
hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
{
struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
size_t i;
struct sshkey **tmp;
if (l->key == NULL)
return 0;
if (l->status != HKF_STATUS_MATCHED) {
/* Record if one of the keys appears on a non-matching line */
for (i = 0; i < ctx->nkeys; i++) {
if (sshkey_equal(l->key, ctx->keys[i])) {
ctx->other_name_seen = 1;
debug3_f("found %s key under different "
"name/addr at %s:%ld",
sshkey_ssh_name(ctx->keys[i]),
l->path, l->linenum);
return 0;
}
}
return 0;
}
/* Don't proceed if revocation or CA markers are present */
/* XXX relax this */
if (l->marker != MRK_NONE) {
debug3_f("hostkeys file %s:%ld has CA/revocation marker",
l->path, l->linenum);
ctx->complex_hostspec = 1;
return 0;
}
/* If CheckHostIP is enabled, then check for mismatched hostname/addr */
if (ctx->ip_str != NULL && strchr(l->hosts, ',') != NULL) {
if ((l->match & HKF_MATCH_HOST) == 0) {
/* Record if address matched a different hostname. */
ctx->other_name_seen = 1;
debug3_f("found address %s against different hostname "
"at %s:%ld", ctx->ip_str, l->path, l->linenum);
return 0;
} else if ((l->match & HKF_MATCH_IP) == 0) {
/* Record if hostname matched a different address. */
ctx->other_name_seen = 1;
debug3_f("found hostname %s against different address "
"at %s:%ld", ctx->host_str, l->path, l->linenum);
}
}
/*
* UpdateHostkeys is skipped for wildcard host names and hostnames
* that contain more than two entries (ssh never writes these).
*/
if (hostspec_is_complex(l->hosts)) {
debug3_f("hostkeys file %s:%ld complex host specification",
l->path, l->linenum);
ctx->complex_hostspec = 1;
return 0;
}
/* Mark off keys we've already seen for this host */
for (i = 0; i < ctx->nkeys; i++) {
if (!sshkey_equal(l->key, ctx->keys[i]))
continue;
debug3_f("found %s key at %s:%ld",
sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
ctx->keys_match[i] |= l->match;
return 0;
}
/* This line contained a key that not offered by the server */
debug3_f("deprecated %s key at %s:%ld", sshkey_ssh_name(l->key),
l->path, l->linenum);
if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1,
sizeof(*ctx->old_keys))) == NULL)
fatal_f("recallocarray failed nold = %zu", ctx->nold);
ctx->old_keys = tmp;
ctx->old_keys[ctx->nold++] = l->key;
l->key = NULL;
return 0;
}
/* callback to search for ctx->old_keys in known_hosts under other names */
static int
hostkeys_check_old(struct hostkey_foreach_line *l, void *_ctx)
{
struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
size_t i;
int hashed;
/* only care about lines that *don't* match the active host spec */
if (l->status == HKF_STATUS_MATCHED || l->key == NULL)
return 0;
hashed = l->match & (HKF_MATCH_HOST_HASHED|HKF_MATCH_IP_HASHED);
for (i = 0; i < ctx->nold; i++) {
if (!sshkey_equal(l->key, ctx->old_keys[i]))
continue;
debug3_f("found deprecated %s key at %s:%ld as %s",
sshkey_ssh_name(ctx->old_keys[i]), l->path, l->linenum,
hashed ? "[HASHED]" : l->hosts);
ctx->old_key_seen = 1;
break;
}
return 0;
}
/*
* Check known_hosts files for deprecated keys under other names. Returns 0
* on success or -1 on failure. Updates ctx->old_key_seen if deprecated keys
* exist under names other than the active hostname/IP.
*/
static int
check_old_keys_othernames(struct hostkeys_update_ctx *ctx)
{
size_t i;
int r;
debug2_f("checking for %zu deprecated keys", ctx->nold);
for (i = 0; i < options.num_user_hostfiles; i++) {
debug3_f("searching %s for %s / %s",
options.user_hostfiles[i], ctx->host_str,
ctx->ip_str ? ctx->ip_str : "(none)");
if ((r = hostkeys_foreach(options.user_hostfiles[i],
hostkeys_check_old, ctx, ctx->host_str, ctx->ip_str,
HKF_WANT_PARSE_KEY, 0)) != 0) {
if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
debug_f("hostkeys file %s does not exist",
options.user_hostfiles[i]);
continue;
}
error_fr(r, "hostkeys_foreach failed for %s",
options.user_hostfiles[i]);
return -1;
}
}
return 0;
}
static void
hostkey_change_preamble(LogLevel loglevel)
{
do_log2(loglevel, "The server has updated its host keys.");
do_log2(loglevel, "These changes were verified by the server's "
"existing trusted key.");
}
static void
update_known_hosts(struct hostkeys_update_ctx *ctx)
{
int r, was_raw = 0, first = 1;
int asking = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK;
LogLevel loglevel = asking ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
char *fp, *response;
size_t i;
struct stat sb;
for (i = 0; i < ctx->nkeys; i++) {
if (!ctx->keys_verified[i])
continue;
if ((fp = sshkey_fingerprint(ctx->keys[i],
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
fatal_f("sshkey_fingerprint failed");
if (first && asking)
hostkey_change_preamble(loglevel);
do_log2(loglevel, "Learned new hostkey: %s %s",
sshkey_type(ctx->keys[i]), fp);
first = 0;
free(fp);
}
for (i = 0; i < ctx->nold; i++) {
if ((fp = sshkey_fingerprint(ctx->old_keys[i],
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
fatal_f("sshkey_fingerprint failed");
if (first && asking)
hostkey_change_preamble(loglevel);
do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
sshkey_type(ctx->old_keys[i]), fp);
first = 0;
free(fp);
}
if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
if (get_saved_tio() != NULL) {
leave_raw_mode(1);
was_raw = 1;
}
response = NULL;
for (i = 0; !quit_pending && i < 3; i++) {
free(response);
response = read_passphrase("Accept updated hostkeys? "
"(yes/no): ", RP_ECHO);
if (strcasecmp(response, "yes") == 0)
break;
else if (quit_pending || response == NULL ||
strcasecmp(response, "no") == 0) {
options.update_hostkeys = 0;
break;
} else {
do_log2(loglevel, "Please enter "
"\"yes\" or \"no\"");
}
}
if (quit_pending || i >= 3 || response == NULL)
options.update_hostkeys = 0;
free(response);
if (was_raw)
enter_raw_mode(1);
}
if (options.update_hostkeys == 0)
return;
/*
* Now that all the keys are verified, we can go ahead and replace
* them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
* cancel the operation).
*/
for (i = 0; i < options.num_user_hostfiles; i++) {
/*
* NB. keys are only added to hostfiles[0], for the rest we
* just delete the hostname entries.
*/
if (stat(options.user_hostfiles[i], &sb) != 0) {
if (errno == ENOENT) {
debug_f("known hosts file %s does not "
"exist", options.user_hostfiles[i]);
} else {
error_f("known hosts file %s "
"inaccessible: %s",
options.user_hostfiles[i], strerror(errno));
}
continue;
}
if ((r = hostfile_replace_entries(options.user_hostfiles[i],
ctx->host_str, ctx->ip_str,
i == 0 ? ctx->keys : NULL, i == 0 ? ctx->nkeys : 0,
options.hash_known_hosts, 0,
options.fingerprint_hash)) != 0) {
error_fr(r, "hostfile_replace_entries failed for %s",
options.user_hostfiles[i]);
}
}
}
static void
client_global_hostkeys_prove_confirm(struct ssh *ssh, int type,
u_int32_t seq, void *_ctx)
{
struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
size_t i, ndone;
struct sshbuf *signdata;
int r, plaintype;
const u_char *sig;
const char *rsa_kexalg = NULL;
char *alg = NULL;
size_t siglen;
if (ctx->nnew == 0)
fatal_f("ctx->nnew == 0"); /* sanity */
if (type != SSH2_MSG_REQUEST_SUCCESS) {
error("Server failed to confirm ownership of "
"private host keys");
hostkeys_update_ctx_free(ctx);
return;
}
if (sshkey_type_plain(sshkey_type_from_name(
ssh->kex->hostkey_alg)) == KEY_RSA)
rsa_kexalg = ssh->kex->hostkey_alg;
if ((signdata = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
/*
* Expect a signature for each of the ctx->nnew private keys we
* haven't seen before. They will be in the same order as the
* ctx->keys where the corresponding ctx->keys_match[i] == 0.
*/
for (ndone = i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_match[i])
continue;
plaintype = sshkey_type_plain(ctx->keys[i]->type);
/* Prepare data to be signed: session ID, unique string, key */
sshbuf_reset(signdata);
if ( (r = sshbuf_put_cstring(signdata,
"hostkeys-prove-00@openssh.com")) != 0 ||
(r = sshbuf_put_stringb(signdata,
ssh->kex->session_id)) != 0 ||
(r = sshkey_puts(ctx->keys[i], signdata)) != 0)
fatal_fr(r, "compose signdata");
/* Extract and verify signature */
if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
error_fr(r, "parse sig");
goto out;
}
if ((r = sshkey_get_sigtype(sig, siglen, &alg)) != 0) {
error_fr(r, "server gave unintelligible signature "
"for %s key %zu", sshkey_type(ctx->keys[i]), i);
goto out;
}
/*
* Special case for RSA keys: if a RSA hostkey was negotiated,
* then use its signature type for verification of RSA hostkey
* proofs. Otherwise, accept only RSA-SHA256/512 signatures.
*/
if (plaintype == KEY_RSA && rsa_kexalg == NULL &&
match_pattern_list(alg, HOSTKEY_PROOF_RSA_ALGS, 0) != 1) {
debug_f("server used untrusted RSA signature algorithm "
"%s for key %zu, disregarding", alg, i);
free(alg);
/* zap the key from the list */
sshkey_free(ctx->keys[i]);
ctx->keys[i] = NULL;
ndone++;
continue;
}
debug3_f("verify %s key %zu using sigalg %s",
sshkey_type(ctx->keys[i]), i, alg);
free(alg);
if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
sshbuf_ptr(signdata), sshbuf_len(signdata),
plaintype == KEY_RSA ? rsa_kexalg : NULL, 0, NULL)) != 0) {
error_fr(r, "server gave bad signature for %s key %zu",
sshkey_type(ctx->keys[i]), i);
goto out;
}
/* Key is good. Mark it as 'seen' */
ctx->keys_verified[i] = 1;
ndone++;
}
/* Shouldn't happen */
if (ndone != ctx->nnew)
fatal_f("ndone != ctx->nnew (%zu / %zu)", ndone, ctx->nnew);
if ((r = sshpkt_get_end(ssh)) != 0) {
error_f("protocol error");
goto out;
}
/* Make the edits to known_hosts */
update_known_hosts(ctx);
out:
hostkeys_update_ctx_free(ctx);
hostkeys_update_complete = 1;
client_repledge();
}
/*
* Returns non-zero if the key is accepted by HostkeyAlgorithms.
* Made slightly less trivial by the multiple RSA signature algorithm names.
*/
static int
key_accepted_by_hostkeyalgs(const struct sshkey *key)
{
const char *ktype = sshkey_ssh_name(key);
const char *hostkeyalgs = options.hostkeyalgorithms;
if (key == NULL || key->type == KEY_UNSPEC)
return 0;
if (key->type == KEY_RSA &&
(match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
return 1;
return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
}
/*
* Handle hostkeys-00@openssh.com global request to inform the client of all
* the server's hostkeys. The keys are checked against the user's
* HostkeyAlgorithms preference before they are accepted.
*/
static int
client_input_hostkeys(struct ssh *ssh)
{
const u_char *blob = NULL;
size_t i, len = 0;
struct sshbuf *buf = NULL;
struct sshkey *key = NULL, **tmp;
int r, prove_sent = 0;
char *fp;
static int hostkeys_seen = 0; /* XXX use struct ssh */
extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
struct hostkeys_update_ctx *ctx = NULL;
u_int want;
if (hostkeys_seen)
fatal_f("server already sent hostkeys");
if (!can_update_hostkeys())
return 1;
hostkeys_seen = 1;
ctx = xcalloc(1, sizeof(*ctx));
while (ssh_packet_remaining(ssh) > 0) {
sshkey_free(key);
key = NULL;
if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
error_fr(r, "parse key");
goto out;
}
if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
do_log2_fr(r, r == SSH_ERR_KEY_TYPE_UNKNOWN ?
SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_ERROR,
"convert key");
continue;
}
fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT);
debug3_f("received %s key %s", sshkey_type(key), fp);
free(fp);
if (!key_accepted_by_hostkeyalgs(key)) {
debug3_f("%s key not permitted by "
"HostkeyAlgorithms", sshkey_ssh_name(key));
continue;
}
/* Skip certs */
if (sshkey_is_cert(key)) {
debug3_f("%s key is a certificate; skipping",
sshkey_ssh_name(key));
continue;
}
/* Ensure keys are unique */
for (i = 0; i < ctx->nkeys; i++) {
if (sshkey_equal(key, ctx->keys[i])) {
error_f("received duplicated %s host key",
sshkey_ssh_name(key));
goto out;
}
}
/* Key is good, record it */
if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1,
sizeof(*ctx->keys))) == NULL)
fatal_f("recallocarray failed nkeys = %zu",
ctx->nkeys);
ctx->keys = tmp;
ctx->keys[ctx->nkeys++] = key;
key = NULL;
}
if (ctx->nkeys == 0) {
debug_f("server sent no hostkeys");
goto out;
}
if ((ctx->keys_match = calloc(ctx->nkeys,
sizeof(*ctx->keys_match))) == NULL ||
(ctx->keys_verified = calloc(ctx->nkeys,
sizeof(*ctx->keys_verified))) == NULL)
fatal_f("calloc failed");
get_hostfile_hostname_ipaddr(host,
options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
options.port, &ctx->host_str,
options.check_host_ip ? &ctx->ip_str : NULL);
/* Find which keys we already know about. */
for (i = 0; i < options.num_user_hostfiles; i++) {
debug_f("searching %s for %s / %s",
options.user_hostfiles[i], ctx->host_str,
ctx->ip_str ? ctx->ip_str : "(none)");
if ((r = hostkeys_foreach(options.user_hostfiles[i],
hostkeys_find, ctx, ctx->host_str, ctx->ip_str,
HKF_WANT_PARSE_KEY, 0)) != 0) {
if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
debug_f("hostkeys file %s does not exist",
options.user_hostfiles[i]);
continue;
}
error_fr(r, "hostkeys_foreach failed for %s",
options.user_hostfiles[i]);
goto out;
}
}
/* Figure out if we have any new keys to add */
ctx->nnew = ctx->nincomplete = 0;
want = HKF_MATCH_HOST | ( options.check_host_ip ? HKF_MATCH_IP : 0);
for (i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_match[i] == 0)
ctx->nnew++;
if ((ctx->keys_match[i] & want) != want)
ctx->nincomplete++;
}
debug3_f("%zu server keys: %zu new, %zu retained, "
"%zu incomplete match. %zu to remove", ctx->nkeys, ctx->nnew,
ctx->nkeys - ctx->nnew - ctx->nincomplete,
ctx->nincomplete, ctx->nold);
if (ctx->nnew == 0 && ctx->nold == 0) {
debug_f("no new or deprecated keys from server");
goto out;
}
/* Various reasons why we cannot proceed with the update */
if (ctx->complex_hostspec) {
debug_f("CA/revocation marker, manual host list or wildcard "
"host pattern found, skipping UserKnownHostsFile update");
goto out;
}
if (ctx->other_name_seen) {
debug_f("host key found matching a different name/address, "
"skipping UserKnownHostsFile update");
goto out;
}
/*
* If removing keys, check whether they appear under different
* names/addresses and refuse to proceed if they do. This avoids
* cases such as hosts with multiple names becoming inconsistent
* with regards to CheckHostIP entries.
* XXX UpdateHostkeys=force to override this (and other) checks?
*/
if (ctx->nold != 0) {
if (check_old_keys_othernames(ctx) != 0)
goto out; /* error already logged */
if (ctx->old_key_seen) {
debug_f("key(s) for %s%s%s exist under other names; "
"skipping UserKnownHostsFile update",
ctx->host_str, ctx->ip_str == NULL ? "" : ",",
ctx->ip_str == NULL ? "" : ctx->ip_str);
goto out;
}
}
if (ctx->nnew == 0) {
/*
* We have some keys to remove or fix matching for.
* We can proceed to do this without requiring a fresh proof
* from the server.
*/
update_known_hosts(ctx);
goto out;
}
/*
* We have received previously-unseen keys from the server.
* Ask the server to confirm ownership of the private halves.
*/
debug3_f("asking server to prove ownership for %zu keys", ctx->nnew);
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh,
"hostkeys-prove-00@openssh.com")) != 0 ||
(r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
fatal_fr(r, "prepare hostkeys-prove");
if ((buf = sshbuf_new()) == NULL)
fatal_f("sshbuf_new");
for (i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_match[i])
continue;
sshbuf_reset(buf);
if ((r = sshkey_putb(ctx->keys[i], buf)) != 0 ||
(r = sshpkt_put_stringb(ssh, buf)) != 0)
fatal_fr(r, "assemble hostkeys-prove");
}
if ((r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send hostkeys-prove");
client_register_global_confirm(
client_global_hostkeys_prove_confirm, ctx);
ctx = NULL; /* will be freed in callback */
prove_sent = 1;
/* Success */
out:
hostkeys_update_ctx_free(ctx);
sshkey_free(key);
sshbuf_free(buf);
if (!prove_sent) {
/* UpdateHostkeys handling completed */
hostkeys_update_complete = 1;
client_repledge();
}
/*
* NB. Return success for all cases. The server doesn't need to know
* what the client does with its hosts file.
*/
return 1;
}
static int
client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
{
char *rtype;
u_char want_reply;
int r, success = 0;
if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 ||
(r = sshpkt_get_u8(ssh, &want_reply)) != 0)
goto out;
debug("client_input_global_request: rtype %s want_reply %d",
rtype, want_reply);
if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
success = client_input_hostkeys(ssh);
if (want_reply) {
if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS :
SSH2_MSG_REQUEST_FAILURE)) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
goto out;
}
r = 0;
out:
free(rtype);
return r;
}
static void
client_send_env(struct ssh *ssh, int id, const char *name, const char *val)
{
int r;
debug("channel %d: setting env %s = \"%s\"", id, name, val);
channel_request_start(ssh, id, "env", 0);
if ((r = sshpkt_put_cstring(ssh, name)) != 0 ||
(r = sshpkt_put_cstring(ssh, val)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send setenv");
}
void
client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
const char *term, struct termios *tiop, int in_fd, struct sshbuf *cmd,
char **env)
{
size_t i, j, len;
int matched, r;
char *name, *val;
Channel *c = NULL;
debug2_f("id %d", id);
if ((c = channel_lookup(ssh, id)) == NULL)
fatal_f("channel %d: unknown channel", id);
ssh_packet_set_interactive(ssh, want_tty,
options.ip_qos_interactive, options.ip_qos_bulk);
if (want_tty) {
struct winsize ws;
/* Store window size in the packet. */
if (ioctl(in_fd, TIOCGWINSZ, &ws) == -1)
memset(&ws, 0, sizeof(ws));
channel_request_start(ssh, id, "pty-req", 1);
client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
if ((r = sshpkt_put_cstring(ssh, term != NULL ? term : ""))
!= 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0)
fatal_fr(r, "build pty-req");
if (tiop == NULL)
tiop = get_saved_tio();
ssh_tty_make_modes(ssh, -1, tiop);
if ((r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send pty-req");
/* XXX wait for reply */
c->client_tty = 1;
}
/* Transfer any environment variables from client to server */
if (options.num_send_env != 0 && env != NULL) {
debug("Sending environment.");
for (i = 0; env[i] != NULL; i++) {
/* Split */
name = xstrdup(env[i]);
if ((val = strchr(name, '=')) == NULL) {
free(name);
continue;
}
*val++ = '\0';
matched = 0;
for (j = 0; j < options.num_send_env; j++) {
if (match_pattern(name, options.send_env[j])) {
matched = 1;
break;
}
}
if (!matched) {
debug3("Ignored env %s", name);
free(name);
continue;
}
client_send_env(ssh, id, name, val);
free(name);
}
}
for (i = 0; i < options.num_setenv; i++) {
/* Split */
name = xstrdup(options.setenv[i]);
if ((val = strchr(name, '=')) == NULL) {
free(name);
continue;
}
*val++ = '\0';
client_send_env(ssh, id, name, val);
free(name);
}
len = sshbuf_len(cmd);
if (len > 0) {
if (len > 900)
len = 900;
if (want_subsystem) {
debug("Sending subsystem: %.*s",
(int)len, (const u_char*)sshbuf_ptr(cmd));
channel_request_start(ssh, id, "subsystem", 1);
client_expect_confirm(ssh, id, "subsystem",
CONFIRM_CLOSE);
} else {
debug("Sending command: %.*s",
(int)len, (const u_char*)sshbuf_ptr(cmd));
channel_request_start(ssh, id, "exec", 1);
client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
}
if ((r = sshpkt_put_stringb(ssh, cmd)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send command");
} else {
channel_request_start(ssh, id, "shell", 1);
client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
if ((r = sshpkt_send(ssh)) != 0)
fatal_fr(r, "send shell");
}
session_setup_complete = 1;
client_repledge();
}
static void
client_init_dispatch(struct ssh *ssh)
{
ssh_dispatch_init(ssh, &dispatch_protocol_error);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
/* rekeying */
ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit);
/* global request reply messages */
ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
}
void
client_stop_mux(void)
{
if (options.control_path != NULL && muxserver_sock != -1)
unlink(options.control_path);
/*
* If we are in persist mode, or don't have a shell, signal that we
* should close when all active channels are closed.
*/
if (options.control_persist || options.session_type == SESSION_TYPE_NONE) {
session_closed = 1;
setproctitle("[stopped mux]");
}
}
/* client specific fatal cleanup */
void
cleanup_exit(int i)
{
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
if (options.control_path != NULL && muxserver_sock != -1)
unlink(options.control_path);
ssh_kill_proxy_command();
_exit(i);
}
Reference in New Issue View Git Blame Copy Permalink