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openssh/clientloop.c
dtucker@openbsd.org 05046d907c upstream Don't reset signal handlers inside handlers. 
The signal handlers from the original ssh1 code on which OpenSSH
is based assume unreliable signals and reinstall their handlers.
Since OpenBSD (and pretty much every current system) has reliable
signals this is not needed.  In the unlikely even that -portable
is still being used on such systems we will deal with it in the
compat layer.  ok deraadt@

OpenBSD-Commit-ID: f53a1015cb6908431b92116130d285d71589612c
2018-02-13 09:29:09 +11:00

2308 lines
64 KiB
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/* $OpenBSD: clientloop.c,v 1.311 2018/02/11 21:16:56 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
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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 "buffer.h"
#include "compat.h"
#include "channels.h"
#include "dispatch.h"
#include "key.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"
/* import options */
extern Options options;
/* Flag indicating that stdin should be redirected from /dev/null. */
extern int stdin_null_flag;
/* Flag indicating that no shell has been requested */
extern int no_shell_flag;
/* Flag indicating that ssh should daemonise after authentication is complete */
extern int fork_after_authentication_flag;
/* 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;
/*
* 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;
/* Flag indicating whether the user's terminal is in non-blocking mode. */
static int in_non_blocking_mode = 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 Buffer 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 u_int x11_refuse_time; /* If >0, refuse x11 opens after this time. */
static void client_init_dispatch(void);
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, Buffer *);
/* Restores stdin to blocking mode. */
static void
leave_non_blocking(void)
{
if (in_non_blocking_mode) {
unset_nonblock(fileno(stdin));
in_non_blocking_mode = 0;
}
}
/*
* 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("%s: cancel scheduled exit", __func__);
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("%s: schedule exit in %d seconds", __func__,
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[1024], 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("%s: display name too long", __func__);
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("%s: mkdtemp: %s",
__func__, strerror(errno));
return -1;
}
do_unlink = 1;
if ((r = snprintf(xauthfile, sizeof(xauthfile),
"%s/xauthfile", xauthdir)) < 0 ||
(size_t)r >= sizeof(xauthfile)) {
error("%s: xauthfile path too long", __func__);
unlink(xauthfile);
rmdir(xauthdir);
return -1;
}
if (timeout >= UINT_MAX - X11_TIMEOUT_SLACK)
x11_timeout_real = UINT_MAX;
else
x11_timeout_real = timeout + X11_TIMEOUT_SLACK;
if ((r = snprintf(cmd, sizeof(cmd),
"%s -f %s generate %s " SSH_X11_PROTO
" untrusted timeout %u 2>" _PATH_DEVNULL,
xauth_path, xauthfile, display,
x11_timeout_real)) < 0 ||
(size_t)r >= sizeof(cmd))
fatal("%s: cmd too long", __func__);
debug2("%s: %s", __func__, cmd);
if (x11_refuse_time == 0) {
now = monotime() + 1;
if (UINT_MAX - timeout < now)
x11_refuse_time = UINT_MAX;
else
x11_refuse_time = now + timeout;
channel_set_x11_refuse_time(ssh,
x11_refuse_time);
}
if (system(cmd) == 0)
generated = 1;
}
/*
* 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) {
snprintf(cmd, sizeof(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);
}
}
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;
/** XXX race */
received_window_change_signal = 0;
debug2("%s: changed", __func__);
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);
explicit_bzero(gc, sizeof(*gc));
free(gc);
}
packet_set_alive_timeouts(0);
return 0;
}
static void
server_alive_check(void)
{
if (packet_inc_alive_timeouts() > options.server_alive_count_max) {
logit("Timeout, server %s not responding.", host);
cleanup_exit(255);
}
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("keepalive@openssh.com");
packet_put_char(1); /* boolean: want reply */
packet_send();
/* Insert an empty placeholder to maintain ordering */
client_register_global_confirm(NULL, NULL);
}
/*
* 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,
fd_set **readsetp, fd_set **writesetp,
int *maxfdp, u_int *nallocp, int rekeying)
{
struct timeval tv, *tvp;
int timeout_secs;
time_t minwait_secs = 0, server_alive_time = 0, now = monotime();
int ret;
/* Add any selections by the channel mechanism. */
channel_prepare_select(active_state, readsetp, writesetp, maxfdp,
nallocp, &minwait_secs);
/* channel_prepare_select could have closed the last channel */
if (session_closed && !channel_still_open(ssh) &&
!packet_have_data_to_write()) {
/* clear mask since we did not call select() */
memset(*readsetp, 0, *nallocp);
memset(*writesetp, 0, *nallocp);
return;
}
FD_SET(connection_in, *readsetp);
/* Select server connection if have data to write to the server. */
if (packet_have_data_to_write())
FD_SET(connection_out, *writesetp);
/*
* Wait for something to happen. This will suspend the process until
* some selected descriptor can be read, written, or has some other
* event pending, or a timeout expires.
*/
timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */
if (options.server_alive_interval > 0) {
timeout_secs = options.server_alive_interval;
server_alive_time = now + options.server_alive_interval;
}
if (options.rekey_interval > 0 && !rekeying)
timeout_secs = MINIMUM(timeout_secs, packet_get_rekey_timeout());
set_control_persist_exit_time(ssh);
if (control_persist_exit_time > 0) {
timeout_secs = MINIMUM(timeout_secs,
control_persist_exit_time - now);
if (timeout_secs < 0)
timeout_secs = 0;
}
if (minwait_secs != 0)
timeout_secs = MINIMUM(timeout_secs, (int)minwait_secs);
if (timeout_secs == INT_MAX)
tvp = NULL;
else {
tv.tv_sec = timeout_secs;
tv.tv_usec = 0;
tvp = &tv;
}
ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
if (ret < 0) {
char buf[100];
/*
* We have to clear the select masks, because we return.
* We have to return, because the mainloop checks for the flags
* set by the signal handlers.
*/
memset(*readsetp, 0, *nallocp);
memset(*writesetp, 0, *nallocp);
if (errno == EINTR)
return;
/* Note: we might still have data in the buffers. */
snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
buffer_append(&stderr_buffer, buf, strlen(buf));
quit_pending = 1;
} else if (ret == 0) {
/*
* Timeout. Could have been either keepalive or rekeying.
* Keepalive we check here, rekeying is checked in clientloop.
*/
if (server_alive_time != 0 && server_alive_time <= monotime())
server_alive_check();
}
}
static void
client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
{
/* Flush stdout and stderr buffers. */
if (buffer_len(bout) > 0)
atomicio(vwrite, fileno(stdout), buffer_ptr(bout),
buffer_len(bout));
if (buffer_len(berr) > 0)
atomicio(vwrite, fileno(stderr), buffer_ptr(berr),
buffer_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(fd_set *readset)
{
int len;
char buf[SSH_IOBUFSZ];
/*
* Read input from the server, and add any such data to the buffer of
* the packet subsystem.
*/
if (FD_ISSET(connection_in, readset)) {
/* Read as much as possible. */
len = read(connection_in, buf, sizeof(buf));
if (len == 0) {
/*
* Received EOF. The remote host has closed the
* connection.
*/
snprintf(buf, sizeof buf,
"Connection to %.300s closed by remote host.\r\n",
host);
buffer_append(&stderr_buffer, buf, strlen(buf));
quit_pending = 1;
return;
}
/*
* There is a kernel bug on Solaris that causes select to
* sometimes wake up even though there is no data available.
*/
if (len < 0 &&
(errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
len = 0;
if (len < 0) {
/*
* An error has encountered. Perhaps there is a
* network problem.
*/
snprintf(buf, sizeof buf,
"Read from remote host %.300s: %.100s\r\n",
host, strerror(errno));
buffer_append(&stderr_buffer, buf, strlen(buf));
quit_pending = 1;
return;
}
packet_process_incoming(buf, len);
}
}
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 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 supress 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) {
buffer_append(c->extended, errmsg, strlen(errmsg));
} 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("%s: last_gc->ref_count = %d",
__func__, 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);
}
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 = 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 {
if (!parse_forward(&fwd, s, dynamic, remote)) {
logit("Bad 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:
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 */
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},
{"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(Buffer *b, int escape_char, int mux_client, int using_stderr)
{
unsigned int i, suppress_flags;
char string[1024];
snprintf(string, sizeof string, "%c?\r\n"
"Supported escape sequences:\r\n", escape_char);
buffer_append(b, string, strlen(string));
suppress_flags =
(mux_client ? SUPPRESS_MUXCLIENT : 0) |
(mux_client ? 0 : SUPPRESS_MUXMASTER) |
(using_stderr ? 0 : SUPPRESS_SYSLOG);
for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
if (esc_txt[i].flags & suppress_flags)
continue;
snprintf(string, sizeof string, " %c%-3s - %s\r\n",
escape_char, esc_txt[i].cmd, esc_txt[i].text);
buffer_append(b, string, strlen(string));
}
snprintf(string, sizeof string,
" %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);
buffer_append(b, string, strlen(string));
}
/*
* Process the characters one by one.
*/
static int
process_escapes(struct ssh *ssh, Channel *c,
Buffer *bin, Buffer *bout, Buffer *berr,
char *buf, int len)
{
char string[1024];
pid_t pid;
int 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. */
snprintf(string, sizeof string, "%c.\r\n",
efc->escape_char);
buffer_append(berr, string, strlen(string));
if (c && c->ctl_chan != -1) {
chan_read_failed(ssh, c);
chan_write_failed(ssh, c);
if (c->detach_user) {
c->detach_user(ssh,
c->self, NULL);
}
c->type = SSH_CHANNEL_ABANDONED;
buffer_clear(c->input);
chan_ibuf_empty(ssh, c);
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);
snprintf(string, sizeof string,
"%c%s escape not available to "
"multiplexed sessions\r\n",
efc->escape_char, b);
buffer_append(berr, string,
strlen(string));
continue;
}
/* Suspend the program. Inform the user */
snprintf(string, sizeof string,
"%c^Z [suspend ssh]\r\n", efc->escape_char);
buffer_append(berr, string, strlen(string));
/* Restore terminal modes and suspend. */
client_suspend_self(bin, bout, berr);
/* We have been continued. */
continue;
case 'B':
snprintf(string, sizeof string,
"%cB\r\n", efc->escape_char);
buffer_append(berr, string, strlen(string));
channel_request_start(ssh, c->self, "break", 0);
packet_put_int(1000);
packet_send();
continue;
case 'R':
if (datafellows & 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()) {
snprintf(string, sizeof string,
"%c%c [Logging to syslog]\r\n",
efc->escape_char, ch);
buffer_append(berr, string,
strlen(string));
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);
snprintf(string, sizeof string,
"%c%c [LogLevel %s]\r\n",
efc->escape_char, ch,
log_level_name(options.log_level));
buffer_append(berr, string, strlen(string));
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);
snprintf(string, sizeof string,
"%c& [backgrounded]\n", efc->escape_char);
buffer_append(berr, string, strlen(string));
/* Fork into background. */
pid = fork();
if (pid < 0) {
error("fork: %.100s", strerror(errno));
continue;
}
if (pid != 0) { /* This is the parent. */
/* The parent just exits. */
exit(0);
}
/* The child continues serving connections. */
buffer_append(bin, "\004", 1);
/* fake EOF on stdin */
return -1;
case '?':
print_escape_help(berr, efc->escape_char,
(c && c->ctl_chan != -1),
log_is_on_stderr());
continue;
case '#':
snprintf(string, sizeof string, "%c#\r\n",
efc->escape_char);
buffer_append(berr, string, strlen(string));
s = channel_open_message(ssh);
buffer_append(berr, s, strlen(s));
free(s);
continue;
case 'C':
if (c && c->ctl_chan != -1)
goto noescape;
process_cmdline(ssh);
continue;
default:
if (ch != efc->escape_char) {
buffer_put_char(bin, efc->escape_char);
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');
buffer_put_char(bin, ch);
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(void)
{
ssh_dispatch_run_fatal(active_state, 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, 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)
{
fd_set *readset = NULL, *writeset = NULL;
double start_time, total_time;
int r, max_fd = 0, max_fd2 = 0, len;
u_int64_t ibytes, obytes;
u_int nalloc = 0;
char buf[100];
debug("Entering interactive session.");
if (options.control_master &&
!option_clear_or_none(options.control_path)) {
debug("pledge: id");
if (pledge("stdio rpath wpath cpath unix inet dns recvfd proc exec id tty",
NULL) == -1)
fatal("%s pledge(): %s", __func__, 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("%s pledge(): %s", __func__, strerror(errno));
} else if (options.update_hostkeys) {
debug("pledge: filesystem full");
if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
NULL) == -1)
fatal("%s pledge(): %s", __func__, strerror(errno));
} else if (!option_clear_or_none(options.proxy_command) ||
fork_after_authentication_flag) {
debug("pledge: proc");
if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
fatal("%s pledge(): %s", __func__, strerror(errno));
} else {
debug("pledge: network");
if (pledge("stdio unix inet dns proc tty", NULL) == -1)
fatal("%s pledge(): %s", __func__, strerror(errno));
}
start_time = monotime_double();
/* Initialize variables. */
last_was_cr = 1;
exit_status = -1;
connection_in = packet_get_connection_in();
connection_out = packet_get_connection_out();
max_fd = MAXIMUM(connection_in, connection_out);
quit_pending = 0;
/* Initialize buffers. */
buffer_init(&stderr_buffer);
client_init_dispatch();
/*
* Set signal handlers, (e.g. to restore non-blocking mode)
* but don't overwrite SIG_IGN, matches behaviour from rsh(1)
*/
if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
signal(SIGHUP, signal_handler);
if (signal(SIGINT, SIG_IGN) != SIG_IGN)
signal(SIGINT, signal_handler);
if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
signal(SIGQUIT, signal_handler);
if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
signal(SIGTERM, signal_handler);
signal(SIGWINCH, window_change_handler);
if (have_pty)
enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
session_ident = ssh2_chan_id;
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);
}
/* 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();
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("%s: kex_start_rekex: %s", __func__,
ssh_err(r));
need_rekeying = 0;
} else {
/*
* Make packets from buffered channel data, and
* enqueue them for sending to the server.
*/
if (packet_not_very_much_data_to_write())
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).
*/
max_fd2 = max_fd;
client_wait_until_can_do_something(ssh, &readset, &writeset,
&max_fd2, &nalloc, ssh_packet_is_rekeying(ssh));
if (quit_pending)
break;
/* Do channel operations unless rekeying in progress. */
if (!ssh_packet_is_rekeying(ssh))
channel_after_select(ssh, readset, writeset);
/* Buffer input from the connection. */
client_process_net_input(readset);
if (quit_pending)
break;
/*
* Send as much buffered packet data as possible to the
* sender.
*/
if (FD_ISSET(connection_out, writeset))
packet_write_poll();
/*
* 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(readset);
free(writeset);
/* Terminate the session. */
/* Stop watching for window change. */
signal(SIGWINCH, SIG_DFL);
packet_start(SSH2_MSG_DISCONNECT);
packet_put_int(SSH2_DISCONNECT_BY_APPLICATION);
packet_put_cstring("disconnected by user");
packet_put_cstring(""); /* language tag */
packet_send();
packet_write_wait();
channel_free_all(ssh);
if (have_pty)
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
/* restore blocking io */
if (!isatty(fileno(stdin)))
unset_nonblock(fileno(stdin));
if (!isatty(fileno(stdout)))
unset_nonblock(fileno(stdout));
if (!isatty(fileno(stderr)))
unset_nonblock(fileno(stderr));
/*
* 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 (no_shell_flag && received_signal == SIGTERM) {
received_signal = 0;
exit_status = 0;
}
if (received_signal) {
verbose("Killed by signal %d.", (int) received_signal);
cleanup_exit(0);
}
/*
* In interactive mode (with pseudo tty) display a message indicating
* that the connection has been closed.
*/
if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
snprintf(buf, sizeof buf,
"Connection to %.64s closed.\r\n", host);
buffer_append(&stderr_buffer, buf, strlen(buf));
}
/* Output any buffered data for stderr. */
if (buffer_len(&stderr_buffer) > 0) {
len = atomicio(vwrite, fileno(stderr),
buffer_ptr(&stderr_buffer), buffer_len(&stderr_buffer));
if (len < 0 || (u_int)len != buffer_len(&stderr_buffer))
error("Write failed flushing stderr buffer.");
else
buffer_consume(&stderr_buffer, len);
}
/* Clear and free any buffers. */
explicit_bzero(buf, sizeof(buf));
buffer_free(&stderr_buffer);
/* Report bytes transferred, and transfer rates. */
total_time = monotime_double() - start_time;
packet_get_bytes(&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_short listen_port, originator_port;
int r;
/* Get rest of the packet */
listen_address = packet_get_string(NULL);
listen_port = packet_get_int();
originator_address = packet_get_string(NULL);
originator_port = packet_get_int();
packet_check_eom();
debug("%s: listen %s port %d, originator %s port %d", __func__,
listen_address, listen_port, originator_address, originator_port);
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("%s: alloc reply", __func__);
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("%s: compose for muxclient %s", __func__,
ssh_err(r));
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;
/* Get the remote path. */
listen_path = packet_get_string(NULL);
/* XXX: Skip reserved field for now. */
if (packet_get_string_ptr(NULL) == NULL)
fatal("%s: packet_get_string_ptr failed", __func__);
packet_check_eom();
debug("%s: %s", __func__, 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_short originator_port;
int 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 && (u_int)monotime() >= x11_refuse_time) {
verbose("Rejected X11 connection after ForwardX11Timeout "
"expired");
return NULL;
}
originator = packet_get_string(NULL);
originator_port = packet_get_int();
packet_check_eom();
/* XXX check permission */
debug("client_request_x11: request from %s %d", 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 ((r = ssh_get_authentication_socket(&sock)) != 0) {
if (r != SSH_ERR_AGENT_NOT_PRESENT)
debug("%s: ssh_get_authentication_socket: %s",
__func__, ssh_err(r));
return NULL;
}
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 *c;
int 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
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring("tun@openssh.com");
packet_put_int(c->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
packet_put_int(tun_mode);
packet_put_int(remote_tun);
packet_send();
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;
int rchan;
u_int rmaxpack, rwindow, len;
ctype = packet_get_string(&len);
rchan = packet_get_int();
rwindow = packet_get_int();
rmaxpack = packet_get_int();
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) {
packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(c->remote_id);
packet_put_int(c->self);
packet_put_int(c->local_window);
packet_put_int(c->local_maxpacket);
packet_send();
}
} else {
debug("failure %s", ctype);
packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(rchan);
packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
packet_put_cstring("open failed");
packet_put_cstring("");
packet_send();
}
free(ctype);
return 0;
}
static int
client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = NULL;
int exitval, id, reply, success = 0;
char *rtype;
id = packet_get_int();
c = channel_lookup(ssh, id);
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
rtype = packet_get_string(NULL);
reply = packet_get_char();
debug("client_input_channel_req: channel %d rtype %s reply %d",
id, rtype, reply);
if (id == -1) {
error("client_input_channel_req: request for channel -1");
} else if (c == NULL) {
error("client_input_channel_req: channel %d: "
"unknown channel", id);
} else if (strcmp(rtype, "eow@openssh.com") == 0) {
packet_check_eom();
chan_rcvd_eow(ssh, c);
} else if (strcmp(rtype, "exit-status") == 0) {
exitval = packet_get_int();
if (c->ctl_chan != -1) {
mux_exit_message(ssh, c, exitval);
success = 1;
} else if (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("%s: no sink for exit-status on channel %d",
__func__, id);
}
packet_check_eom();
}
if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
if (!c->have_remote_id)
fatal("%s: channel %d: no remote_id",
__func__, c->self);
packet_start(success ?
SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
packet_put_int(c->remote_id);
packet_send();
}
free(rtype);
return 0;
}
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_seen is filled in by hostkeys_find() and later (for new
* keys) by client_global_hostkeys_private_confirm().
*/
struct sshkey **keys;
int *keys_seen;
size_t nkeys, nnew;
/*
* 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;
};
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_seen);
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);
}
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->status != HKF_STATUS_MATCHED || l->key == NULL)
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])) {
debug3("%s: found %s key at %s:%ld", __func__,
sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
ctx->keys_seen[i] = 1;
return 0;
}
}
/* This line contained a key that not offered by the server */
debug3("%s: deprecated %s key at %s:%ld", __func__,
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("%s: recallocarray failed nold = %zu",
__func__, ctx->nold);
ctx->old_keys = tmp;
ctx->old_keys[ctx->nold++] = l->key;
l->key = NULL;
return 0;
}
static void
update_known_hosts(struct hostkeys_update_ctx *ctx)
{
int r, was_raw = 0;
int loglevel = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK ?
SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
char *fp, *response;
size_t i;
for (i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_seen[i] != 2)
continue;
if ((fp = sshkey_fingerprint(ctx->keys[i],
options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
fatal("%s: sshkey_fingerprint failed", __func__);
do_log2(loglevel, "Learned new hostkey: %s %s",
sshkey_type(ctx->keys[i]), fp);
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("%s: sshkey_fingerprint failed", __func__);
do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
sshkey_type(ctx->old_keys[i]), fp);
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);
}
/*
* 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).
*/
if (options.update_hostkeys != 0 &&
(r = hostfile_replace_entries(options.user_hostfiles[0],
ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,
options.hash_known_hosts, 0,
options.fingerprint_hash)) != 0)
error("%s: hostfile_replace_entries failed: %s",
__func__, ssh_err(r));
}
static void
client_global_hostkeys_private_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, kexsigtype, use_kexsigtype;
const u_char *sig;
size_t siglen;
if (ctx->nnew == 0)
fatal("%s: ctx->nnew == 0", __func__); /* sanity */
if (type != SSH2_MSG_REQUEST_SUCCESS) {
error("Server failed to confirm ownership of "
"private host keys");
hostkeys_update_ctx_free(ctx);
return;
}
kexsigtype = sshkey_type_plain(
sshkey_type_from_name(ssh->kex->hostkey_alg));
if ((signdata = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
/* Don't want to accidentally accept an unbound signature */
if (ssh->kex->session_id_len == 0)
fatal("%s: ssh->kex->session_id_len == 0", __func__);
/*
* 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_seen[i] == 0.
*/
for (ndone = i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_seen[i])
continue;
/* 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_string(signdata, ssh->kex->session_id,
ssh->kex->session_id_len)) != 0 ||
(r = sshkey_puts(ctx->keys[i], signdata)) != 0)
fatal("%s: failed to prepare signature: %s",
__func__, ssh_err(r));
/* Extract and verify signature */
if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
error("%s: couldn't parse message: %s",
__func__, ssh_err(r));
goto out;
}
/*
* For RSA keys, prefer to use the signature type negotiated
* during KEX to the default (SHA1).
*/
use_kexsigtype = kexsigtype == KEY_RSA &&
sshkey_type_plain(ctx->keys[i]->type) == KEY_RSA;
if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
sshbuf_ptr(signdata), sshbuf_len(signdata),
use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 0) {
error("%s: server gave bad signature for %s key %zu",
__func__, sshkey_type(ctx->keys[i]), i);
goto out;
}
/* Key is good. Mark it as 'seen' */
ctx->keys_seen[i] = 2;
ndone++;
}
if (ndone != ctx->nnew)
fatal("%s: ndone != ctx->nnew (%zu / %zu)", __func__,
ndone, ctx->nnew); /* Shouldn't happen */
ssh_packet_check_eom(ssh);
/* Make the edits to known_hosts */
update_known_hosts(ctx);
out:
hostkeys_update_ctx_free(ctx);
}
/*
* 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 != NULL ?
options.hostkeyalgorithms : KEX_DEFAULT_PK_ALG;
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(void)
{
struct ssh *ssh = active_state; /* XXX */
const u_char *blob = NULL;
size_t i, len = 0;
struct sshbuf *buf = NULL;
struct sshkey *key = NULL, **tmp;
int r;
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;
if (hostkeys_seen)
fatal("%s: server already sent hostkeys", __func__);
if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
options.batch_mode)
return 1; /* won't ask in batchmode, so don't even try */
if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
return 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("%s: couldn't parse message: %s",
__func__, ssh_err(r));
goto out;
}
if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
error("%s: parse key: %s", __func__, ssh_err(r));
goto out;
}
fp = sshkey_fingerprint(key, options.fingerprint_hash,
SSH_FP_DEFAULT);
debug3("%s: received %s key %s", __func__,
sshkey_type(key), fp);
free(fp);
if (!key_accepted_by_hostkeyalgs(key)) {
debug3("%s: %s key not permitted by HostkeyAlgorithms",
__func__, sshkey_ssh_name(key));
continue;
}
/* Skip certs */
if (sshkey_is_cert(key)) {
debug3("%s: %s key is a certificate; skipping",
__func__, sshkey_ssh_name(key));
continue;
}
/* Ensure keys are unique */
for (i = 0; i < ctx->nkeys; i++) {
if (sshkey_equal(key, ctx->keys[i])) {
error("%s: received duplicated %s host key",
__func__, 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("%s: recallocarray failed nkeys = %zu",
__func__, ctx->nkeys);
ctx->keys = tmp;
ctx->keys[ctx->nkeys++] = key;
key = NULL;
}
if (ctx->nkeys == 0) {
debug("%s: server sent no hostkeys", __func__);
goto out;
}
if ((ctx->keys_seen = calloc(ctx->nkeys,
sizeof(*ctx->keys_seen))) == NULL)
fatal("%s: calloc failed", __func__);
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. */
if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find,
ctx, ctx->host_str, ctx->ip_str,
HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
goto out;
}
/* Figure out if we have any new keys to add */
ctx->nnew = 0;
for (i = 0; i < ctx->nkeys; i++) {
if (!ctx->keys_seen[i])
ctx->nnew++;
}
debug3("%s: %zu keys from server: %zu new, %zu retained. %zu to remove",
__func__, ctx->nkeys, ctx->nnew, ctx->nkeys - ctx->nnew, ctx->nold);
if (ctx->nnew == 0 && ctx->nold != 0) {
/* We have some keys to remove. Just do it. */
update_known_hosts(ctx);
} else if (ctx->nnew != 0) {
/*
* We have received hitherto-unseen keys from the server.
* Ask the server to confirm ownership of the private halves.
*/
debug3("%s: asking server to prove ownership for %zu keys",
__func__, 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("%s: cannot prepare packet: %s",
__func__, ssh_err(r));
if ((buf = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
for (i = 0; i < ctx->nkeys; i++) {
if (ctx->keys_seen[i])
continue;
sshbuf_reset(buf);
if ((r = sshkey_putb(ctx->keys[i], buf)) != 0)
fatal("%s: sshkey_putb: %s",
__func__, ssh_err(r));
if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
fatal("%s: sshpkt_put_string: %s",
__func__, ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: sshpkt_send: %s", __func__, ssh_err(r));
client_register_global_confirm(
client_global_hostkeys_private_confirm, ctx);
ctx = NULL; /* will be freed in callback */
}
/* Success */
out:
hostkeys_update_ctx_free(ctx);
sshkey_free(key);
sshbuf_free(buf);
/*
* 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;
int want_reply;
int success = 0;
rtype = packet_get_cstring(NULL);
want_reply = packet_get_char();
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();
if (want_reply) {
packet_start(success ?
SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
packet_send();
packet_write_wait();
}
free(rtype);
return 0;
}
void
client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env)
{
int len;
Channel *c = NULL;
debug2("%s: id %d", __func__, id);
if ((c = channel_lookup(ssh, id)) == NULL)
fatal("%s: channel %d: unknown channel", __func__, id);
packet_set_interactive(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) < 0)
memset(&ws, 0, sizeof(ws));
channel_request_start(ssh, id, "pty-req", 1);
client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
packet_put_cstring(term != NULL ? term : "");
packet_put_int((u_int)ws.ws_col);
packet_put_int((u_int)ws.ws_row);
packet_put_int((u_int)ws.ws_xpixel);
packet_put_int((u_int)ws.ws_ypixel);
if (tiop == NULL)
tiop = get_saved_tio();
tty_make_modes(-1, tiop);
packet_send();
/* XXX wait for reply */
c->client_tty = 1;
}
/* Transfer any environment variables from client to server */
if (options.num_send_env != 0 && env != NULL) {
int i, j, matched;
char *name, *val;
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;
}
debug("Sending env %s = %s", name, val);
channel_request_start(ssh, id, "env", 0);
packet_put_cstring(name);
packet_put_cstring(val);
packet_send();
free(name);
}
}
len = buffer_len(cmd);
if (len > 0) {
if (len > 900)
len = 900;
if (want_subsystem) {
debug("Sending subsystem: %.*s",
len, (u_char*)buffer_ptr(cmd));
channel_request_start(ssh, id, "subsystem", 1);
client_expect_confirm(ssh, id, "subsystem",
CONFIRM_CLOSE);
} else {
debug("Sending command: %.*s",
len, (u_char*)buffer_ptr(cmd));
channel_request_start(ssh, id, "exec", 1);
client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
}
packet_put_string(buffer_ptr(cmd), buffer_len(cmd));
packet_send();
} else {
channel_request_start(ssh, id, "shell", 1);
client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
packet_send();
}
}
static void
client_init_dispatch(void)
{
dispatch_init(&dispatch_protocol_error);
dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
/* rekeying */
dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
/* global request reply messages */
dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
dispatch_set(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 || no_shell_flag) {
session_closed = 1;
setproctitle("[stopped mux]");
}
}
/* client specific fatal cleanup */
void
cleanup_exit(int i)
{
leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
leave_non_blocking();
if (options.control_path != NULL && muxserver_sock != -1)
unlink(options.control_path);
ssh_kill_proxy_command();
_exit(i);
}
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