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putty-source/unix/plink.c
Simon Tatham 5f5c710cf3 New option to reject 'trivial' success of userauth. 
Suggested by Manfred Kaiser, who also wrote most of this patch
(although outlying parts, like documentation and SSH-1 support, are by
me).

This is a second line of defence against the kind of spoofing attacks
in which a malicious or compromised SSH server rushes the client
through the userauth phase of SSH without actually requiring any auth
inputs (passwords or signatures or whatever), and then at the start of
the connection phase it presents something like a spoof prompt,
intended to be taken for part of userauth by the user but in fact with
some more sinister purpose.

Our existing line of defence against this is the trust sigil system,
and as far as I know, that's still working. This option allows a bit of
extra defence in depth: if you don't expect your SSH server to
trivially accept authentication in the first place, then enabling this
option will cause PuTTY to disconnect if it unexpectedly does so,
without the user having to spot the presence or absence of a fiddly
little sigil anywhere.

Several types of authentication count as 'trivial'. The obvious one is
the SSH-2 "none" method, which clients always try first so that the
failure message will tell them what else they can try, and which a
server can instead accept in order to authenticate you unconditionally.
But there are two other ways to do it that we know of: one is to run
keyboard-interactive authentication and send an empty INFO_REQUEST
packet containing no actual prompts for the user, and another even
weirder one is to send USERAUTH_SUCCESS in response to the user's
preliminary *offer* of a public key (instead of sending the usual PK_OK
to request an actual signature from the key).

This new option detects all of those, by clearing the 'is_trivial_auth'
flag only when we send some kind of substantive authentication response
(be it a password, a k-i prompt response, a signature, or a GSSAPI
token). So even if there's a further path through the userauth maze we
haven't spotted, that somehow avoids sending anything substantive, this
strategy should still pick it up.
2021-06-19 21:34:56 +01:00

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/*
* PLink - a command-line (stdin/stdout) variant of PuTTY.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <assert.h>
#include <stdarg.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#include <pwd.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include "putty.h"
#include "ssh.h"
#include "storage.h"
#include "tree234.h"
#define MAX_STDIN_BACKLOG 4096
static LogContext *logctx;
static struct termios orig_termios;
void cmdline_error(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
console_print_error_msg_fmt_v("plink", fmt, ap);
va_end(ap);
exit(1);
}
static bool local_tty = false; /* do we have a local tty? */
static Backend *backend;
static Conf *conf;
/*
* Default settings that are specific to Unix plink.
*/
char *platform_default_s(const char *name)
{
if (!strcmp(name, "TermType"))
return dupstr(getenv("TERM"));
if (!strcmp(name, "SerialLine"))
return dupstr("/dev/ttyS0");
return NULL;
}
bool platform_default_b(const char *name, bool def)
{
return def;
}
int platform_default_i(const char *name, int def)
{
return def;
}
FontSpec *platform_default_fontspec(const char *name)
{
return fontspec_new("");
}
Filename *platform_default_filename(const char *name)
{
if (!strcmp(name, "LogFileName"))
return filename_from_str("putty.log");
else
return filename_from_str("");
}
char *x_get_default(const char *key)
{
return NULL; /* this is a stub */
}
static void plink_echoedit_update(Seat *seat, bool echo, bool edit)
{
/* Update stdin read mode to reflect changes in line discipline. */
struct termios mode;
if (!local_tty) return;
mode = orig_termios;
if (echo)
mode.c_lflag |= ECHO;
else
mode.c_lflag &= ~ECHO;
if (edit) {
mode.c_iflag |= ICRNL;
mode.c_lflag |= ISIG | ICANON;
mode.c_oflag |= OPOST;
} else {
mode.c_iflag &= ~ICRNL;
mode.c_lflag &= ~(ISIG | ICANON);
mode.c_oflag &= ~OPOST;
/* Solaris sets these to unhelpful values */
mode.c_cc[VMIN] = 1;
mode.c_cc[VTIME] = 0;
/* FIXME: perhaps what we do with IXON/IXOFF should be an
* argument to the echoedit_update() method, to allow
* implementation of SSH-2 "xon-xoff" and Rlogin's
* equivalent? */
mode.c_iflag &= ~IXON;
mode.c_iflag &= ~IXOFF;
}
/*
* Mark parity errors and (more important) BREAK on input. This
* is more complex than it need be because POSIX-2001 suggests
* that escaping of valid 0xff in the input stream is dependent on
* IGNPAR being clear even though marking of BREAK isn't. NetBSD
* 2.0 goes one worse and makes it dependent on INPCK too. We
* deal with this by forcing these flags into a useful state and
* then faking the state in which we found them in from_tty() if
* we get passed a parity or framing error.
*/
mode.c_iflag = (mode.c_iflag | INPCK | PARMRK) & ~IGNPAR;
tcsetattr(STDIN_FILENO, TCSANOW, &mode);
}
/* Helper function to extract a special character from a termios. */
static char *get_ttychar(struct termios *t, int index)
{
cc_t c = t->c_cc[index];
#if defined(_POSIX_VDISABLE)
if (c == _POSIX_VDISABLE)
return dupstr("");
#endif
return dupprintf("^<%d>", c);
}
static char *plink_get_ttymode(Seat *seat, const char *mode)
{
/*
* Propagate appropriate terminal modes from the local terminal,
* if any.
*/
if (!local_tty) return NULL;
#define GET_CHAR(ourname, uxname) \
do { \
if (strcmp(mode, ourname) == 0) \
return get_ttychar(&orig_termios, uxname); \
} while(0)
#define GET_BOOL(ourname, uxname, uxmemb, transform) \
do { \
if (strcmp(mode, ourname) == 0) { \
bool b = (orig_termios.uxmemb & uxname) != 0; \
transform; \
return dupprintf("%d", b); \
} \
} while (0)
/*
* Modes that want to be the same on all terminal devices involved.
*/
/* All the special characters supported by SSH */
#if defined(VINTR)
GET_CHAR("INTR", VINTR);
#endif
#if defined(VQUIT)
GET_CHAR("QUIT", VQUIT);
#endif
#if defined(VERASE)
GET_CHAR("ERASE", VERASE);
#endif
#if defined(VKILL)
GET_CHAR("KILL", VKILL);
#endif
#if defined(VEOF)
GET_CHAR("EOF", VEOF);
#endif
#if defined(VEOL)
GET_CHAR("EOL", VEOL);
#endif
#if defined(VEOL2)
GET_CHAR("EOL2", VEOL2);
#endif
#if defined(VSTART)
GET_CHAR("START", VSTART);
#endif
#if defined(VSTOP)
GET_CHAR("STOP", VSTOP);
#endif
#if defined(VSUSP)
GET_CHAR("SUSP", VSUSP);
#endif
#if defined(VDSUSP)
GET_CHAR("DSUSP", VDSUSP);
#endif
#if defined(VREPRINT)
GET_CHAR("REPRINT", VREPRINT);
#endif
#if defined(VWERASE)
GET_CHAR("WERASE", VWERASE);
#endif
#if defined(VLNEXT)
GET_CHAR("LNEXT", VLNEXT);
#endif
#if defined(VFLUSH)
GET_CHAR("FLUSH", VFLUSH);
#endif
#if defined(VSWTCH)
GET_CHAR("SWTCH", VSWTCH);
#endif
#if defined(VSTATUS)
GET_CHAR("STATUS", VSTATUS);
#endif
#if defined(VDISCARD)
GET_CHAR("DISCARD", VDISCARD);
#endif
/* Modes that "configure" other major modes. These should probably be
* considered as user preferences. */
/* Configuration of ICANON */
#if defined(ECHOK)
GET_BOOL("ECHOK", ECHOK, c_lflag, );
#endif
#if defined(ECHOKE)
GET_BOOL("ECHOKE", ECHOKE, c_lflag, );
#endif
#if defined(ECHOE)
GET_BOOL("ECHOE", ECHOE, c_lflag, );
#endif
#if defined(ECHONL)
GET_BOOL("ECHONL", ECHONL, c_lflag, );
#endif
#if defined(XCASE)
GET_BOOL("XCASE", XCASE, c_lflag, );
#endif
#if defined(IUTF8)
GET_BOOL("IUTF8", IUTF8, c_iflag, );
#endif
/* Configuration of ECHO */
#if defined(ECHOCTL)
GET_BOOL("ECHOCTL", ECHOCTL, c_lflag, );
#endif
/* Configuration of IXON/IXOFF */
#if defined(IXANY)
GET_BOOL("IXANY", IXANY, c_iflag, );
#endif
/* Configuration of OPOST */
#if defined(OLCUC)
GET_BOOL("OLCUC", OLCUC, c_oflag, );
#endif
#if defined(ONLCR)
GET_BOOL("ONLCR", ONLCR, c_oflag, );
#endif
#if defined(OCRNL)
GET_BOOL("OCRNL", OCRNL, c_oflag, );
#endif
#if defined(ONOCR)
GET_BOOL("ONOCR", ONOCR, c_oflag, );
#endif
#if defined(ONLRET)
GET_BOOL("ONLRET", ONLRET, c_oflag, );
#endif
/*
* Modes that want to be set in only one place, and that we have
* squashed locally.
*/
#if defined(ISIG)
GET_BOOL("ISIG", ISIG, c_lflag, );
#endif
#if defined(ICANON)
GET_BOOL("ICANON", ICANON, c_lflag, );
#endif
#if defined(ECHO)
GET_BOOL("ECHO", ECHO, c_lflag, );
#endif
#if defined(IXON)
GET_BOOL("IXON", IXON, c_iflag, );
#endif
#if defined(IXOFF)
GET_BOOL("IXOFF", IXOFF, c_iflag, );
#endif
#if defined(OPOST)
GET_BOOL("OPOST", OPOST, c_oflag, );
#endif
/*
* We do not propagate the following modes:
* - Parity/serial settings, which are a local affair and don't
* make sense propagated over SSH's 8-bit byte-stream.
* IGNPAR PARMRK INPCK CS7 CS8 PARENB PARODD
* - Things that want to be enabled in one place that we don't
* squash locally.
* IUCLC
* - Status bits.
* PENDIN
* - Things I don't know what to do with. (FIXME)
* ISTRIP IMAXBEL NOFLSH TOSTOP IEXTEN
* INLCR IGNCR ICRNL
*/
#undef GET_CHAR
#undef GET_BOOL
/* Fall through to here for unrecognised names, or ones that are
* unsupported on this platform */
return NULL;
}
void cleanup_termios(void)
{
if (local_tty)
tcsetattr(STDIN_FILENO, TCSANOW, &orig_termios);
}
static bufchain stdout_data, stderr_data;
static bufchain_sink stdout_bcs, stderr_bcs;
static StripCtrlChars *stdout_scc, *stderr_scc;
static BinarySink *stdout_bs, *stderr_bs;
static enum { EOF_NO, EOF_PENDING, EOF_SENT } outgoingeof;
size_t try_output(bool is_stderr)
{
bufchain *chain = (is_stderr ? &stderr_data : &stdout_data);
int fd = (is_stderr ? STDERR_FILENO : STDOUT_FILENO);
ssize_t ret;
if (bufchain_size(chain) > 0) {
bool prev_nonblock = nonblock(fd);
ptrlen senddata;
do {
senddata = bufchain_prefix(chain);
ret = write(fd, senddata.ptr, senddata.len);
if (ret > 0)
bufchain_consume(chain, ret);
} while (ret == senddata.len && bufchain_size(chain) != 0);
if (!prev_nonblock)
no_nonblock(fd);
if (ret < 0 && errno != EAGAIN) {
perror(is_stderr ? "stderr: write" : "stdout: write");
exit(1);
}
}
if (outgoingeof == EOF_PENDING && bufchain_size(&stdout_data) == 0) {
close(STDOUT_FILENO);
outgoingeof = EOF_SENT;
}
return bufchain_size(&stdout_data) + bufchain_size(&stderr_data);
}
static size_t plink_output(
Seat *seat, bool is_stderr, const void *data, size_t len)
{
assert(is_stderr || outgoingeof == EOF_NO);
BinarySink *bs = is_stderr ? stderr_bs : stdout_bs;
put_data(bs, data, len);
return try_output(is_stderr);
}
static bool plink_eof(Seat *seat)
{
assert(outgoingeof == EOF_NO);
outgoingeof = EOF_PENDING;
try_output(false);
return false; /* do not respond to incoming EOF with outgoing */
}
static int plink_get_userpass_input(Seat *seat, prompts_t *p, bufchain *input)
{
int ret;
ret = cmdline_get_passwd_input(p);
if (ret == -1)
ret = console_get_userpass_input(p);
return ret;
}
static bool plink_seat_interactive(Seat *seat)
{
return (!*conf_get_str(conf, CONF_remote_cmd) &&
!*conf_get_str(conf, CONF_remote_cmd2) &&
!*conf_get_str(conf, CONF_ssh_nc_host));
}
static const SeatVtable plink_seat_vt = {
.output = plink_output,
.eof = plink_eof,
.get_userpass_input = plink_get_userpass_input,
.notify_remote_exit = nullseat_notify_remote_exit,
.notify_remote_disconnect = nullseat_notify_remote_disconnect,
.connection_fatal = console_connection_fatal,
.update_specials_menu = nullseat_update_specials_menu,
.get_ttymode = plink_get_ttymode,
.set_busy_status = nullseat_set_busy_status,
.verify_ssh_host_key = console_verify_ssh_host_key,
.confirm_weak_crypto_primitive = console_confirm_weak_crypto_primitive,
.confirm_weak_cached_hostkey = console_confirm_weak_cached_hostkey,
.is_utf8 = nullseat_is_never_utf8,
.echoedit_update = plink_echoedit_update,
.get_x_display = nullseat_get_x_display,
.get_windowid = nullseat_get_windowid,
.get_window_pixel_size = nullseat_get_window_pixel_size,
.stripctrl_new = console_stripctrl_new,
.set_trust_status = console_set_trust_status,
.verbose = cmdline_seat_verbose,
.interactive = plink_seat_interactive,
.get_cursor_position = nullseat_get_cursor_position,
};
static Seat plink_seat[1] = {{ &plink_seat_vt }};
/*
* Handle data from a local tty in PARMRK format.
*/
static void from_tty(void *vbuf, unsigned len)
{
char *p, *q, *end, *buf = vbuf;
static enum {NORMAL, FF, FF00} state = NORMAL;
p = buf; end = buf + len;
while (p < end) {
switch (state) {
case NORMAL:
if (*p == '\xff') {
p++;
state = FF;
} else {
q = memchr(p, '\xff', end - p);
if (q == NULL) q = end;
backend_send(backend, p, q - p);
p = q;
}
break;
case FF:
if (*p == '\xff') {
backend_send(backend, p, 1);
p++;
state = NORMAL;
} else if (*p == '\0') {
p++;
state = FF00;
} else abort();
break;
case FF00:
if (*p == '\0') {
backend_special(backend, SS_BRK, 0);
} else {
/*
* Pretend that PARMRK wasn't set. This involves
* faking what INPCK and IGNPAR would have done if
* we hadn't overridden them. Unfortunately, we
* can't do this entirely correctly because INPCK
* distinguishes between framing and parity
* errors, but PARMRK format represents both in
* the same way. We assume that parity errors are
* more common than framing errors, and hence
* treat all input errors as being subject to
* INPCK.
*/
if (orig_termios.c_iflag & INPCK) {
/* If IGNPAR is set, we throw away the character. */
if (!(orig_termios.c_iflag & IGNPAR)) {
/* PE/FE get passed on as NUL. */
*p = 0;
backend_send(backend, p, 1);
}
} else {
/* INPCK not set. Assume we got a parity error. */
backend_send(backend, p, 1);
}
}
p++;
state = NORMAL;
}
}
}
static int signalpipe[2];
void sigwinch(int signum)
{
if (write(signalpipe[1], "x", 1) <= 0)
/* not much we can do about it */;
}
/*
* Short description of parameters.
*/
static void usage(void)
{
printf("Plink: command-line connection utility\n");
printf("%s\n", ver);
printf("Usage: plink [options] [user@]host [command]\n");
printf(" (\"host\" can also be a PuTTY saved session name)\n");
printf("Options:\n");
printf(" -V print version information and exit\n");
printf(" -pgpfp print PGP key fingerprints and exit\n");
printf(" -v show verbose messages\n");
printf(" -load sessname Load settings from saved session\n");
printf(" -ssh -telnet -rlogin -raw -serial\n");
printf(" force use of a particular protocol\n");
printf(" -ssh-connection\n");
printf(" force use of the bare ssh-connection protocol\n");
printf(" -P port connect to specified port\n");
printf(" -l user connect with specified username\n");
printf(" -batch disable all interactive prompts\n");
printf(" -proxycmd command\n");
printf(" use 'command' as local proxy\n");
printf(" -sercfg configuration-string (e.g. 19200,8,n,1,X)\n");
printf(" Specify the serial configuration (serial only)\n");
printf("The following options only apply to SSH connections:\n");
printf(" -pw passw login with specified password\n");
printf(" -D [listen-IP:]listen-port\n");
printf(" Dynamic SOCKS-based port forwarding\n");
printf(" -L [listen-IP:]listen-port:host:port\n");
printf(" Forward local port to remote address\n");
printf(" -R [listen-IP:]listen-port:host:port\n");
printf(" Forward remote port to local address\n");
printf(" -X -x enable / disable X11 forwarding\n");
printf(" -A -a enable / disable agent forwarding\n");
printf(" -t -T enable / disable pty allocation\n");
printf(" -1 -2 force use of particular SSH protocol version\n");
printf(" -4 -6 force use of IPv4 or IPv6\n");
printf(" -C enable compression\n");
printf(" -i key private key file for user authentication\n");
printf(" -noagent disable use of Pageant\n");
printf(" -agent enable use of Pageant\n");
printf(" -no-trivial-auth\n");
printf(" disconnect if SSH authentication succeeds trivially\n");
printf(" -noshare disable use of connection sharing\n");
printf(" -share enable use of connection sharing\n");
printf(" -hostkey keyid\n");
printf(" manually specify a host key (may be repeated)\n");
printf(" -sanitise-stderr, -sanitise-stdout, "
"-no-sanitise-stderr, -no-sanitise-stdout\n");
printf(" do/don't strip control chars from standard "
"output/error\n");
printf(" -no-antispoof omit anti-spoofing prompt after "
"authentication\n");
printf(" -m file read remote command(s) from file\n");
printf(" -s remote command is an SSH subsystem (SSH-2 only)\n");
printf(" -N don't start a shell/command (SSH-2 only)\n");
printf(" -nc host:port\n");
printf(" open tunnel in place of session (SSH-2 only)\n");
printf(" -sshlog file\n");
printf(" -sshrawlog file\n");
printf(" log protocol details to a file\n");
printf(" -logoverwrite\n");
printf(" -logappend\n");
printf(" control what happens when a log file already exists\n");
printf(" -shareexists\n");
printf(" test whether a connection-sharing upstream exists\n");
exit(1);
}
static void version(void)
{
char *buildinfo_text = buildinfo("\n");
printf("plink: %s\n%s\n", ver, buildinfo_text);
sfree(buildinfo_text);
exit(0);
}
void frontend_net_error_pending(void) {}
const bool share_can_be_downstream = true;
const bool share_can_be_upstream = true;
const bool buildinfo_gtk_relevant = false;
const unsigned cmdline_tooltype =
TOOLTYPE_HOST_ARG |
TOOLTYPE_HOST_ARG_CAN_BE_SESSION |
TOOLTYPE_HOST_ARG_PROTOCOL_PREFIX |
TOOLTYPE_HOST_ARG_FROM_LAUNCHABLE_LOAD;
static bool seen_stdin_eof = false;
static bool plink_pw_setup(void *vctx, pollwrapper *pw)
{
pollwrap_add_fd_rwx(pw, signalpipe[0], SELECT_R);
if (!seen_stdin_eof &&
backend_connected(backend) &&
backend_sendok(backend) &&
backend_sendbuffer(backend) < MAX_STDIN_BACKLOG) {
/* If we're OK to send, then try to read from stdin. */
pollwrap_add_fd_rwx(pw, STDIN_FILENO, SELECT_R);
}
if (bufchain_size(&stdout_data) > 0) {
/* If we have data for stdout, try to write to stdout. */
pollwrap_add_fd_rwx(pw, STDOUT_FILENO, SELECT_W);
}
if (bufchain_size(&stderr_data) > 0) {
/* If we have data for stderr, try to write to stderr. */
pollwrap_add_fd_rwx(pw, STDERR_FILENO, SELECT_W);
}
return true;
}
static void plink_pw_check(void *vctx, pollwrapper *pw)
{
if (pollwrap_check_fd_rwx(pw, signalpipe[0], SELECT_R)) {
char c[1];
struct winsize size;
if (read(signalpipe[0], c, 1) <= 0)
/* ignore error */;
/* ignore its value; it'll be `x' */
if (ioctl(STDIN_FILENO, TIOCGWINSZ, (void *)&size) >= 0)
backend_size(backend, size.ws_col, size.ws_row);
}
if (pollwrap_check_fd_rwx(pw, STDIN_FILENO, SELECT_R)) {
char buf[4096];
int ret;
if (backend_connected(backend)) {
ret = read(STDIN_FILENO, buf, sizeof(buf));
noise_ultralight(NOISE_SOURCE_IOLEN, ret);
if (ret < 0) {
perror("stdin: read");
exit(1);
} else if (ret == 0) {
backend_special(backend, SS_EOF, 0);
seen_stdin_eof = true;
} else {
if (local_tty)
from_tty(buf, ret);
else
backend_send(backend, buf, ret);
}
}
}
if (pollwrap_check_fd_rwx(pw, STDOUT_FILENO, SELECT_W)) {
backend_unthrottle(backend, try_output(false));
}
if (pollwrap_check_fd_rwx(pw, STDERR_FILENO, SELECT_W)) {
backend_unthrottle(backend, try_output(true));
}
}
static bool plink_continue(void *vctx, bool found_any_fd,
bool ran_any_callback)
{
if (!backend_connected(backend) &&
bufchain_size(&stdout_data) == 0 && bufchain_size(&stderr_data) == 0)
return false; /* terminate main loop */
return true;
}
int main(int argc, char **argv)
{
int exitcode;
bool errors;
enum TriState sanitise_stdout = AUTO, sanitise_stderr = AUTO;
bool use_subsystem = false;
bool just_test_share_exists = false;
struct winsize size;
const struct BackendVtable *backvt;
/*
* Initialise port and protocol to sensible defaults. (These
* will be overridden by more or less anything.)
*/
settings_set_default_protocol(PROT_SSH);
settings_set_default_port(22);
bufchain_init(&stdout_data);
bufchain_init(&stderr_data);
bufchain_sink_init(&stdout_bcs, &stdout_data);
bufchain_sink_init(&stderr_bcs, &stderr_data);
stdout_bs = BinarySink_UPCAST(&stdout_bcs);
stderr_bs = BinarySink_UPCAST(&stderr_bcs);
outgoingeof = EOF_NO;
stderr_tty_init();
/*
* Process the command line.
*/
conf = conf_new();
do_defaults(NULL, conf);
settings_set_default_protocol(conf_get_int(conf, CONF_protocol));
settings_set_default_port(conf_get_int(conf, CONF_port));
errors = false;
{
/*
* Override the default protocol if PLINK_PROTOCOL is set.
*/
char *p = getenv("PLINK_PROTOCOL");
if (p) {
const struct BackendVtable *vt = backend_vt_from_name(p);
if (vt) {
settings_set_default_protocol(vt->protocol);
settings_set_default_port(vt->default_port);
conf_set_int(conf, CONF_protocol, vt->protocol);
conf_set_int(conf, CONF_port, vt->default_port);
}
}
}
while (--argc) {
char *p = *++argv;
int ret = cmdline_process_param(p, (argc > 1 ? argv[1] : NULL),
1, conf);
if (ret == -2) {
fprintf(stderr,
"plink: option \"%s\" requires an argument\n", p);
errors = true;
} else if (ret == 2) {
--argc, ++argv;
} else if (ret == 1) {
continue;
} else if (!strcmp(p, "-batch")) {
console_batch_mode = true;
} else if (!strcmp(p, "-s")) {
/* Save status to write to conf later. */
use_subsystem = true;
} else if (!strcmp(p, "-V") || !strcmp(p, "--version")) {
version();
} else if (!strcmp(p, "--help")) {
usage();
exit(0);
} else if (!strcmp(p, "-pgpfp")) {
pgp_fingerprints();
exit(1);
} else if (!strcmp(p, "-o")) {
if (argc <= 1) {
fprintf(stderr,
"plink: option \"-o\" requires an argument\n");
errors = true;
} else {
--argc;
/* Explicitly pass "plink" in place of appname for
* error reporting purposes. appname will have been
* set by be_foo.c to something more generic, probably
* "PuTTY". */
provide_xrm_string(*++argv, "plink");
}
} else if (!strcmp(p, "-shareexists")) {
just_test_share_exists = true;
} else if (!strcmp(p, "-fuzznet")) {
conf_set_int(conf, CONF_proxy_type, PROXY_FUZZ);
conf_set_str(conf, CONF_proxy_telnet_command, "%host");
} else if (!strcmp(p, "-sanitise-stdout") ||
!strcmp(p, "-sanitize-stdout")) {
sanitise_stdout = FORCE_ON;
} else if (!strcmp(p, "-no-sanitise-stdout") ||
!strcmp(p, "-no-sanitize-stdout")) {
sanitise_stdout = FORCE_OFF;
} else if (!strcmp(p, "-sanitise-stderr") ||
!strcmp(p, "-sanitize-stderr")) {
sanitise_stderr = FORCE_ON;
} else if (!strcmp(p, "-no-sanitise-stderr") ||
!strcmp(p, "-no-sanitize-stderr")) {
sanitise_stderr = FORCE_OFF;
} else if (!strcmp(p, "-no-antispoof")) {
console_antispoof_prompt = false;
} else if (*p != '-') {
strbuf *cmdbuf = strbuf_new();
while (argc > 0) {
if (cmdbuf->len > 0)
put_byte(cmdbuf, ' '); /* add space separator */
put_datapl(cmdbuf, ptrlen_from_asciz(p));
if (--argc > 0)
p = *++argv;
}
conf_set_str(conf, CONF_remote_cmd, cmdbuf->s);
conf_set_str(conf, CONF_remote_cmd2, "");
conf_set_bool(conf, CONF_nopty, true); /* command => no tty */
strbuf_free(cmdbuf);
break; /* done with cmdline */
} else {
fprintf(stderr, "plink: unknown option \"%s\"\n", p);
errors = true;
}
}
if (errors)
return 1;
if (!cmdline_host_ok(conf)) {
usage();
}
prepare_session(conf);
/*
* Perform command-line overrides on session configuration.
*/
cmdline_run_saved(conf);
/*
* If we have no better ideas for the remote username, use the local
* one, as 'ssh' does.
*/
if (conf_get_str(conf, CONF_username)[0] == '\0') {
char *user = get_username();
if (user) {
conf_set_str(conf, CONF_username, user);
sfree(user);
}
}
/*
* Apply subsystem status.
*/
if (use_subsystem)
conf_set_bool(conf, CONF_ssh_subsys, true);
/*
* Select protocol. This is farmed out into a table in a
* separate file to enable an ssh-free variant.
*/
backvt = backend_vt_from_proto(conf_get_int(conf, CONF_protocol));
if (!backvt) {
fprintf(stderr,
"Internal fault: Unsupported protocol found\n");
return 1;
}
if (backvt->flags & BACKEND_NEEDS_TERMINAL) {
fprintf(stderr,
"Plink doesn't support %s, which needs terminal emulation\n",
backvt->displayname);
return 1;
}
/*
* Block SIGPIPE, so that we'll get EPIPE individually on
* particular network connections that go wrong.
*/
putty_signal(SIGPIPE, SIG_IGN);
/*
* Set up the pipe we'll use to tell us about SIGWINCH.
*/
if (pipe(signalpipe) < 0) {
perror("pipe");
exit(1);
}
/* We don't want the signal handler to block if the pipe's full. */
nonblock(signalpipe[0]);
nonblock(signalpipe[1]);
cloexec(signalpipe[0]);
cloexec(signalpipe[1]);
putty_signal(SIGWINCH, sigwinch);
/*
* Now that we've got the SIGWINCH handler installed, try to find
* out the initial terminal size.
*/
if (ioctl(STDIN_FILENO, TIOCGWINSZ, &size) >= 0) {
conf_set_int(conf, CONF_width, size.ws_col);
conf_set_int(conf, CONF_height, size.ws_row);
}
/*
* Decide whether to sanitise control sequences out of standard
* output and standard error.
*
* If we weren't given a command-line override, we do this if (a)
* the fd in question is pointing at a terminal, and (b) we aren't
* trying to allocate a terminal as part of the session.
*
* (Rationale: the risk of control sequences is that they cause
* confusion when sent to a local terminal, so if there isn't one,
* no problem. Also, if we allocate a remote terminal, then we
* sent a terminal type, i.e. we told it what kind of escape
* sequences we _like_, i.e. we were expecting to receive some.)
*/
if (sanitise_stdout == FORCE_ON ||
(sanitise_stdout == AUTO && isatty(STDOUT_FILENO) &&
conf_get_bool(conf, CONF_nopty))) {
stdout_scc = stripctrl_new(stdout_bs, true, L'\0');
stdout_bs = BinarySink_UPCAST(stdout_scc);
}
if (sanitise_stderr == FORCE_ON ||
(sanitise_stderr == AUTO && isatty(STDERR_FILENO) &&
conf_get_bool(conf, CONF_nopty))) {
stderr_scc = stripctrl_new(stderr_bs, true, L'\0');
stderr_bs = BinarySink_UPCAST(stderr_scc);
}
sk_init();
uxsel_init();
/*
* Plink doesn't provide any way to add forwardings after the
* connection is set up, so if there are none now, we can safely set
* the "simple" flag.
*/
if (conf_get_int(conf, CONF_protocol) == PROT_SSH &&
!conf_get_bool(conf, CONF_x11_forward) &&
!conf_get_bool(conf, CONF_agentfwd) &&
!conf_get_str_nthstrkey(conf, CONF_portfwd, 0))
conf_set_bool(conf, CONF_ssh_simple, true);
if (just_test_share_exists) {
if (!backvt->test_for_upstream) {
fprintf(stderr, "Connection sharing not supported for this "
"connection type (%s)'\n", backvt->displayname);
return 1;
}
if (backvt->test_for_upstream(conf_get_str(conf, CONF_host),
conf_get_int(conf, CONF_port), conf))
return 0;
else
return 1;
}
/*
* Start up the connection.
*/
logctx = log_init(console_cli_logpolicy, conf);
{
char *error, *realhost;
/* nodelay is only useful if stdin is a terminal device */
bool nodelay = conf_get_bool(conf, CONF_tcp_nodelay) && isatty(0);
/* This is a good place for a fuzzer to fork us. */
#ifdef __AFL_HAVE_MANUAL_CONTROL
__AFL_INIT();
#endif
error = backend_init(backvt, plink_seat, &backend, logctx, conf,
conf_get_str(conf, CONF_host),
conf_get_int(conf, CONF_port),
&realhost, nodelay,
conf_get_bool(conf, CONF_tcp_keepalives));
if (error) {
fprintf(stderr, "Unable to open connection:\n%s\n", error);
sfree(error);
return 1;
}
ldisc_create(conf, NULL, backend, plink_seat);
sfree(realhost);
}
/*
* Set up the initial console mode. We don't care if this call
* fails, because we know we aren't necessarily running in a
* console.
*/
local_tty = (tcgetattr(STDIN_FILENO, &orig_termios) == 0);
atexit(cleanup_termios);
seat_echoedit_update(plink_seat, 1, 1);
cli_main_loop(plink_pw_setup, plink_pw_check, plink_continue, NULL);
exitcode = backend_exitcode(backend);
if (exitcode < 0) {
fprintf(stderr, "Remote process exit code unavailable\n");
exitcode = 1; /* this is an error condition */
}
cleanup_exit(exitcode);
return exitcode; /* shouldn't happen, but placates gcc */
}
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