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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* This file contains functions for generic socket connection forwarding.
* There is also code for initiating connection forwarding for X11 connections,
* arbitrary tcp/ip connections, and the authentication agent connection.
*
* 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".
*
* SSH2 support added by Markus Friedl.
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
* Copyright (c) 1999 Dug Song. All rights reserved.
* 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.
*/
#include "includes.h"
RCSID("$OpenBSD: channels.c,v 1.195 2003/09/16 21:02:40 markus Exp $");
#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
#include "packet.h"
#include "xmalloc.h"
#include "log.h"
#include "misc.h"
#include "channels.h"
#include "compat.h"
#include "canohost.h"
#include "key.h"
#include "authfd.h"
#include "pathnames.h"
#include "bufaux.h"
/* -- channel core */
/*
* Pointer to an array containing all allocated channels. The array is
* dynamically extended as needed.
*/
static Channel **channels = NULL;
/*
* Size of the channel array. All slots of the array must always be
* initialized (at least the type field); unused slots set to NULL
*/
static int channels_alloc = 0;
/*
* Maximum file descriptor value used in any of the channels. This is
* updated in channel_new.
*/
static int channel_max_fd = 0;
/* -- tcp forwarding */
/*
* Data structure for storing which hosts are permitted for forward requests.
* The local sides of any remote forwards are stored in this array to prevent
* a corrupt remote server from accessing arbitrary TCP/IP ports on our local
* network (which might be behind a firewall).
*/
typedef struct {
char *host_to_connect; /* Connect to 'host'. */
u_short port_to_connect; /* Connect to 'port'. */
u_short listen_port; /* Remote side should listen port number. */
} ForwardPermission;
/* List of all permitted host/port pairs to connect. */
static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
/* Number of permitted host/port pairs in the array. */
static int num_permitted_opens = 0;
/*
* If this is true, all opens are permitted. This is the case on the server
* on which we have to trust the client anyway, and the user could do
* anything after logging in anyway.
*/
static int all_opens_permitted = 0;
/* -- X11 forwarding */
/* Maximum number of fake X11 displays to try. */
#define MAX_DISPLAYS 1000
/* Saved X11 authentication protocol name. */
static char *x11_saved_proto = NULL;
/* Saved X11 authentication data. This is the real data. */
static char *x11_saved_data = NULL;
static u_int x11_saved_data_len = 0;
/*
* Fake X11 authentication data. This is what the server will be sending us;
* we should replace any occurrences of this by the real data.
*/
static char *x11_fake_data = NULL;
static u_int x11_fake_data_len;
/* -- agent forwarding */
#define NUM_SOCKS 10
/* AF_UNSPEC or AF_INET or AF_INET6 */
static int IPv4or6 = AF_UNSPEC;
/* helper */
static void port_open_helper(Channel *c, char *rtype);
/* -- channel core */
Channel *
channel_lookup(int id)
{
Channel *c;
if (id < 0 || id >= channels_alloc) {
logit("channel_lookup: %d: bad id", id);
return NULL;
}
c = channels[id];
if (c == NULL) {
logit("channel_lookup: %d: bad id: channel free", id);
return NULL;
}
return c;
}
/*
* Register filedescriptors for a channel, used when allocating a channel or
* when the channel consumer/producer is ready, e.g. shell exec'd
*/
static void
channel_register_fds(Channel *c, int rfd, int wfd, int efd,
int extusage, int nonblock)
{
/* Update the maximum file descriptor value. */
channel_max_fd = MAX(channel_max_fd, rfd);
channel_max_fd = MAX(channel_max_fd, wfd);
channel_max_fd = MAX(channel_max_fd, efd);
/* XXX set close-on-exec -markus */
c->rfd = rfd;
c->wfd = wfd;
c->sock = (rfd == wfd) ? rfd : -1;
c->efd = efd;
c->extended_usage = extusage;
/* XXX ugly hack: nonblock is only set by the server */
if (nonblock && isatty(c->rfd)) {
debug2("channel %d: rfd %d isatty", c->self, c->rfd);
c->isatty = 1;
if (!isatty(c->wfd)) {
error("channel %d: wfd %d is not a tty?",
c->self, c->wfd);
}
} else {
c->isatty = 0;
}
c->wfd_isatty = isatty(c->wfd);
/* enable nonblocking mode */
if (nonblock) {
if (rfd != -1)
set_nonblock(rfd);
if (wfd != -1)
set_nonblock(wfd);
if (efd != -1)
set_nonblock(efd);
}
}
/*
* Allocate a new channel object and set its type and socket. This will cause
* remote_name to be freed.
*/
Channel *
channel_new(char *ctype, int type, int rfd, int wfd, int efd,
u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
{
int i, found;
Channel *c;
/* Do initial allocation if this is the first call. */
if (channels_alloc == 0) {
channels_alloc = 10;
channels = xmalloc(channels_alloc * sizeof(Channel *));
for (i = 0; i < channels_alloc; i++)
channels[i] = NULL;
fatal_add_cleanup((void (*) (void *)) channel_free_all, NULL);
}
/* Try to find a free slot where to put the new channel. */
for (found = -1, i = 0; i < channels_alloc; i++)
if (channels[i] == NULL) {
/* Found a free slot. */
found = i;
break;
}
if (found == -1) {
/* There are no free slots. Take last+1 slot and expand the array. */
found = channels_alloc;
if (channels_alloc > 10000)
fatal("channel_new: internal error: channels_alloc %d "
"too big.", channels_alloc);
channels = xrealloc(channels,
(channels_alloc + 10) * sizeof(Channel *));
channels_alloc += 10;
debug2("channel: expanding %d", channels_alloc);
for (i = found; i < channels_alloc; i++)
channels[i] = NULL;
}
/* Initialize and return new channel. */
c = channels[found] = xmalloc(sizeof(Channel));
memset(c, 0, sizeof(Channel));
buffer_init(&c->input);
buffer_init(&c->output);
buffer_init(&c->extended);
c->ostate = CHAN_OUTPUT_OPEN;
c->istate = CHAN_INPUT_OPEN;
c->flags = 0;
channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
c->self = found;
c->type = type;
c->ctype = ctype;
c->local_window = window;
c->local_window_max = window;
c->local_consumed = 0;
c->local_maxpacket = maxpack;
c->remote_id = -1;
c->remote_name = xstrdup(remote_name);
c->remote_window = 0;
c->remote_maxpacket = 0;
c->force_drain = 0;
c->single_connection = 0;
c->detach_user = NULL;
c->confirm = NULL;
c->input_filter = NULL;
debug("channel %d: new [%s]", found, remote_name);
return c;
}
static int
channel_find_maxfd(void)
{
int i, max = 0;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL) {
max = MAX(max, c->rfd);
max = MAX(max, c->wfd);
max = MAX(max, c->efd);
}
}
return max;
}
int
channel_close_fd(int *fdp)
{
int ret = 0, fd = *fdp;
if (fd != -1) {
ret = close(fd);
*fdp = -1;
if (fd == channel_max_fd)
channel_max_fd = channel_find_maxfd();
}
return ret;
}
/* Close all channel fd/socket. */
static void
channel_close_fds(Channel *c)
{
debug3("channel %d: close_fds r %d w %d e %d",
c->self, c->rfd, c->wfd, c->efd);
channel_close_fd(&c->sock);
channel_close_fd(&c->rfd);
channel_close_fd(&c->wfd);
channel_close_fd(&c->efd);
}
/* Free the channel and close its fd/socket. */
void
channel_free(Channel *c)
{
char *s;
int i, n;
for (n = 0, i = 0; i < channels_alloc; i++)
if (channels[i])
n++;
debug("channel %d: free: %s, nchannels %d", c->self,
c->remote_name ? c->remote_name : "???", n);
s = channel_open_message();
debug3("channel %d: status: %s", c->self, s);
xfree(s);
if (c->sock != -1)
shutdown(c->sock, SHUT_RDWR);
channel_close_fds(c);
buffer_free(&c->input);
buffer_free(&c->output);
buffer_free(&c->extended);
if (c->remote_name) {
xfree(c->remote_name);
c->remote_name = NULL;
}
channels[c->self] = NULL;
xfree(c);
}
void
channel_free_all(void)
{
int i;
for (i = 0; i < channels_alloc; i++)
if (channels[i] != NULL)
channel_free(channels[i]);
}
/*
* Closes the sockets/fds of all channels. This is used to close extra file
* descriptors after a fork.
*/
void
channel_close_all(void)
{
int i;
for (i = 0; i < channels_alloc; i++)
if (channels[i] != NULL)
channel_close_fds(channels[i]);
}
/*
* Stop listening to channels.
*/
void
channel_stop_listening(void)
{
int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL) {
switch (c->type) {
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_X11_LISTENER:
channel_close_fd(&c->sock);
channel_free(c);
break;
}
}
}
}
/*
* Returns true if no channel has too much buffered data, and false if one or
* more channel is overfull.
*/
int
channel_not_very_much_buffered_data(void)
{
u_int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
#if 0
if (!compat20 &&
buffer_len(&c->input) > packet_get_maxsize()) {
debug2("channel %d: big input buffer %d",
c->self, buffer_len(&c->input));
return 0;
}
#endif
if (buffer_len(&c->output) > packet_get_maxsize()) {
debug2("channel %d: big output buffer %u > %u",
c->self, buffer_len(&c->output),
packet_get_maxsize());
return 0;
}
}
}
return 1;
}
/* Returns true if any channel is still open. */
int
channel_still_open(void)
{
int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL)
continue;
switch (c->type) {
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
continue;
case SSH_CHANNEL_LARVAL:
if (!compat20)
fatal("cannot happen: SSH_CHANNEL_LARVAL");
continue;
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
return 1;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
if (!compat13)
fatal("cannot happen: OUT_DRAIN");
return 1;
default:
fatal("channel_still_open: bad channel type %d", c->type);
/* NOTREACHED */
}
}
return 0;
}
/* Returns the id of an open channel suitable for keepaliving */
int
channel_find_open(void)
{
int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL)
continue;
switch (c->type) {
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
continue;
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
return i;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
if (!compat13)
fatal("cannot happen: OUT_DRAIN");
return i;
default:
fatal("channel_find_open: bad channel type %d", c->type);
/* NOTREACHED */
}
}
return -1;
}
/*
* Returns a message describing the currently open forwarded connections,
* suitable for sending to the client. The message contains crlf pairs for
* newlines.
*/
char *
channel_open_message(void)
{
Buffer buffer;
Channel *c;
char buf[1024], *cp;
int i;
buffer_init(&buffer);
snprintf(buf, sizeof buf, "The following connections are open:\r\n");
buffer_append(&buffer, buf, strlen(buf));
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL)
continue;
switch (c->type) {
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_ZOMBIE:
continue;
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
snprintf(buf, sizeof buf, " #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d)\r\n",
c->self, c->remote_name,
c->type, c->remote_id,
c->istate, buffer_len(&c->input),
c->ostate, buffer_len(&c->output),
c->rfd, c->wfd);
buffer_append(&buffer, buf, strlen(buf));
continue;
default:
fatal("channel_open_message: bad channel type %d", c->type);
/* NOTREACHED */
}
}
buffer_append(&buffer, "\0", 1);
cp = xstrdup(buffer_ptr(&buffer));
buffer_free(&buffer);
return cp;
}
void
channel_send_open(int id)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_send_open: %d: bad id", id);
return;
}
debug2("channel %d: send open", id);
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring(c->ctype);
packet_put_int(c->self);
packet_put_int(c->local_window);
packet_put_int(c->local_maxpacket);
packet_send();
}
void
channel_request_start(int id, char *service, int wantconfirm)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_request_start: %d: unknown channel id", id);
return;
}
debug2("channel %d: request %s", id, service) ;
packet_start(SSH2_MSG_CHANNEL_REQUEST);
packet_put_int(c->remote_id);
packet_put_cstring(service);
packet_put_char(wantconfirm);
}
void
channel_register_confirm(int id, channel_callback_fn *fn)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_register_comfirm: %d: bad id", id);
return;
}
c->confirm = fn;
}
void
channel_register_cleanup(int id, channel_callback_fn *fn)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_register_cleanup: %d: bad id", id);
return;
}
c->detach_user = fn;
}
void
channel_cancel_cleanup(int id)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_cancel_cleanup: %d: bad id", id);
return;
}
c->detach_user = NULL;
}
void
channel_register_filter(int id, channel_filter_fn *fn)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_register_filter: %d: bad id", id);
return;
}
c->input_filter = fn;
}
void
channel_set_fds(int id, int rfd, int wfd, int efd,
int extusage, int nonblock, u_int window_max)
{
Channel *c = channel_lookup(id);
if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
fatal("channel_activate for non-larval channel %d.", id);
channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
c->type = SSH_CHANNEL_OPEN;
c->local_window = c->local_window_max = window_max;
packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
packet_put_int(c->remote_id);
packet_put_int(c->local_window);
packet_send();
}
/*
* 'channel_pre*' are called just before select() to add any bits relevant to
* channels in the select bitmasks.
*/
/*
* 'channel_post*': perform any appropriate operations for channels which
* have events pending.
*/
typedef void chan_fn(Channel *c, fd_set * readset, fd_set * writeset);
chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
static void
channel_pre_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
FD_SET(c->sock, readset);
}
static void
channel_pre_connecting(Channel *c, fd_set * readset, fd_set * writeset)
{
debug3("channel %d: waiting for connection", c->self);
FD_SET(c->sock, writeset);
}
static void
channel_pre_open_13(Channel *c, fd_set * readset, fd_set * writeset)
{
if (buffer_len(&c->input) < packet_get_maxsize())
FD_SET(c->sock, readset);
if (buffer_len(&c->output) > 0)
FD_SET(c->sock, writeset);
}
static void
channel_pre_open(Channel *c, fd_set * readset, fd_set * writeset)
{
u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
if (c->istate == CHAN_INPUT_OPEN &&
limit > 0 &&
buffer_len(&c->input) < limit)
FD_SET(c->rfd, readset);
if (c->ostate == CHAN_OUTPUT_OPEN ||
c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
if (buffer_len(&c->output) > 0) {
FD_SET(c->wfd, writeset);
} else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
debug2("channel %d: obuf_empty delayed efd %d/(%d)",
c->self, c->efd, buffer_len(&c->extended));
else
chan_obuf_empty(c);
}
}
/** XXX check close conditions, too */
if (compat20 && c->efd != -1) {
if (c->extended_usage == CHAN_EXTENDED_WRITE &&
buffer_len(&c->extended) > 0)
FD_SET(c->efd, writeset);
else if (!(c->flags & CHAN_EOF_SENT) &&
c->extended_usage == CHAN_EXTENDED_READ &&
buffer_len(&c->extended) < c->remote_window)
FD_SET(c->efd, readset);
}
}
static void
channel_pre_input_draining(Channel *c, fd_set * readset, fd_set * writeset)
{
if (buffer_len(&c->input) == 0) {
packet_start(SSH_MSG_CHANNEL_CLOSE);
packet_put_int(c->remote_id);
packet_send();
c->type = SSH_CHANNEL_CLOSED;
debug2("channel %d: closing after input drain.", c->self);
}
}
static void
channel_pre_output_draining(Channel *c, fd_set * readset, fd_set * writeset)
{
if (buffer_len(&c->output) == 0)
chan_mark_dead(c);
else
FD_SET(c->sock, writeset);
}
/*
* This is a special state for X11 authentication spoofing. An opened X11
* connection (when authentication spoofing is being done) remains in this
* state until the first packet has been completely read. The authentication
* data in that packet is then substituted by the real data if it matches the
* fake data, and the channel is put into normal mode.
* XXX All this happens at the client side.
* Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
*/
static int
x11_open_helper(Buffer *b)
{
u_char *ucp;
u_int proto_len, data_len;
/* Check if the fixed size part of the packet is in buffer. */
if (buffer_len(b) < 12)
return 0;
/* Parse the lengths of variable-length fields. */
ucp = buffer_ptr(b);
if (ucp[0] == 0x42) { /* Byte order MSB first. */
proto_len = 256 * ucp[6] + ucp[7];
data_len = 256 * ucp[8] + ucp[9];
} else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
proto_len = ucp[6] + 256 * ucp[7];
data_len = ucp[8] + 256 * ucp[9];
} else {
debug2("Initial X11 packet contains bad byte order byte: 0x%x",
ucp[0]);
return -1;
}
/* Check if the whole packet is in buffer. */
if (buffer_len(b) <
12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
return 0;
/* Check if authentication protocol matches. */
if (proto_len != strlen(x11_saved_proto) ||
memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
debug2("X11 connection uses different authentication protocol.");
return -1;
}
/* Check if authentication data matches our fake data. */
if (data_len != x11_fake_data_len ||
memcmp(ucp + 12 + ((proto_len + 3) & ~3),
x11_fake_data, x11_fake_data_len) != 0) {
debug2("X11 auth data does not match fake data.");
return -1;
}
/* Check fake data length */
if (x11_fake_data_len != x11_saved_data_len) {
error("X11 fake_data_len %d != saved_data_len %d",
x11_fake_data_len, x11_saved_data_len);
return -1;
}
/*
* Received authentication protocol and data match
* our fake data. Substitute the fake data with real
* data.
*/
memcpy(ucp + 12 + ((proto_len + 3) & ~3),
x11_saved_data, x11_saved_data_len);
return 1;
}
static void
channel_pre_x11_open_13(Channel *c, fd_set * readset, fd_set * writeset)
{
int ret = x11_open_helper(&c->output);
if (ret == 1) {
/* Start normal processing for the channel. */
c->type = SSH_CHANNEL_OPEN;
channel_pre_open_13(c, readset, writeset);
} else if (ret == -1) {
/*
* We have received an X11 connection that has bad
* authentication information.
*/
logit("X11 connection rejected because of wrong authentication.");
buffer_clear(&c->input);
buffer_clear(&c->output);
channel_close_fd(&c->sock);
c->sock = -1;
c->type = SSH_CHANNEL_CLOSED;
packet_start(SSH_MSG_CHANNEL_CLOSE);
packet_put_int(c->remote_id);
packet_send();
}
}
static void
channel_pre_x11_open(Channel *c, fd_set * readset, fd_set * writeset)
{
int ret = x11_open_helper(&c->output);
/* c->force_drain = 1; */
if (ret == 1) {
c->type = SSH_CHANNEL_OPEN;
channel_pre_open(c, readset, writeset);
} else if (ret == -1) {
logit("X11 connection rejected because of wrong authentication.");
debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
chan_read_failed(c);
buffer_clear(&c->input);
chan_ibuf_empty(c);
buffer_clear(&c->output);
/* for proto v1, the peer will send an IEOF */
if (compat20)
chan_write_failed(c);
else
c->type = SSH_CHANNEL_OPEN;
debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
}
}
/* try to decode a socks4 header */
static int
channel_decode_socks4(Channel *c, fd_set * readset, fd_set * writeset)
{
char *p, *host;
int len, have, i, found;
char username[256];
struct {
u_int8_t version;
u_int8_t command;
u_int16_t dest_port;
struct in_addr dest_addr;
} s4_req, s4_rsp;
debug2("channel %d: decode socks4", c->self);
have = buffer_len(&c->input);
len = sizeof(s4_req);
if (have < len)
return 0;
p = buffer_ptr(&c->input);
for (found = 0, i = len; i < have; i++) {
if (p[i] == '\0') {
found = 1;
break;
}
if (i > 1024) {
/* the peer is probably sending garbage */
debug("channel %d: decode socks4: too long",
c->self);
return -1;
}
}
if (!found)
return 0;
buffer_get(&c->input, (char *)&s4_req.version, 1);
buffer_get(&c->input, (char *)&s4_req.command, 1);
buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
have = buffer_len(&c->input);
p = buffer_ptr(&c->input);
len = strlen(p);
debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
if (len > have)
fatal("channel %d: decode socks4: len %d > have %d",
c->self, len, have);
strlcpy(username, p, sizeof(username));
buffer_consume(&c->input, len);
buffer_consume(&c->input, 1); /* trailing '\0' */
host = inet_ntoa(s4_req.dest_addr);
strlcpy(c->path, host, sizeof(c->path));
c->host_port = ntohs(s4_req.dest_port);
debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
c->self, host, c->host_port, s4_req.command);
if (s4_req.command != 1) {
debug("channel %d: cannot handle: socks4 cn %d",
c->self, s4_req.command);
return -1;
}
s4_rsp.version = 0; /* vn: 0 for reply */
s4_rsp.command = 90; /* cd: req granted */
s4_rsp.dest_port = 0; /* ignored */
s4_rsp.dest_addr.s_addr = INADDR_ANY; /* ignored */
buffer_append(&c->output, (char *)&s4_rsp, sizeof(s4_rsp));
return 1;
}
/* try to decode a socks5 header */
#define SSH_SOCKS5_AUTHDONE 0x1000
#define SSH_SOCKS5_NOAUTH 0x00
#define SSH_SOCKS5_IPV4 0x01
#define SSH_SOCKS5_DOMAIN 0x03
#define SSH_SOCKS5_IPV6 0x04
#define SSH_SOCKS5_CONNECT 0x01
#define SSH_SOCKS5_SUCCESS 0x00
static int
channel_decode_socks5(Channel *c, fd_set * readset, fd_set * writeset)
{
struct {
u_int8_t version;
u_int8_t command;
u_int8_t reserved;
u_int8_t atyp;
} s5_req, s5_rsp;
u_int16_t dest_port;
u_char *p, dest_addr[255+1];
int i, have, found, nmethods, addrlen, af;
debug2("channel %d: decode socks5", c->self);
p = buffer_ptr(&c->input);
if (p[0] != 0x05)
return -1;
have = buffer_len(&c->input);
if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
/* format: ver | nmethods | methods */
if (have < 2)
return 0;
nmethods = p[1];
if (have < nmethods + 2)
return 0;
/* look for method: "NO AUTHENTICATION REQUIRED" */
for (found = 0, i = 2 ; i < nmethods + 2; i++) {
if (p[i] == SSH_SOCKS5_NOAUTH ) {
found = 1;
break;
}
}
if (!found) {
debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
c->self);
return -1;
}
buffer_consume(&c->input, nmethods + 2);
buffer_put_char(&c->output, 0x05); /* version */
buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
FD_SET(c->sock, writeset);
c->flags |= SSH_SOCKS5_AUTHDONE;
debug2("channel %d: socks5 auth done", c->self);
return 0; /* need more */
}
debug2("channel %d: socks5 post auth", c->self);
if (have < sizeof(s5_req)+1)
return 0; /* need more */
memcpy((char *)&s5_req, p, sizeof(s5_req));
if (s5_req.version != 0x05 ||
s5_req.command != SSH_SOCKS5_CONNECT ||
s5_req.reserved != 0x00) {
debug2("channel %d: only socks5 connect supported", c->self);
return -1;
}
switch(s5_req.atyp){
case SSH_SOCKS5_IPV4:
addrlen = 4;
af = AF_INET;
break;
case SSH_SOCKS5_DOMAIN:
addrlen = p[sizeof(s5_req)];
af = -1;
break;
case SSH_SOCKS5_IPV6:
addrlen = 16;
af = AF_INET6;
break;
default:
debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
return -1;
}
if (have < 4 + addrlen + 2)
return 0;
buffer_consume(&c->input, sizeof(s5_req));
if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
buffer_consume(&c->input, 1); /* host string length */
buffer_get(&c->input, (char *)&dest_addr, addrlen);
buffer_get(&c->input, (char *)&dest_port, 2);
dest_addr[addrlen] = '\0';
if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
strlcpy(c->path, dest_addr, sizeof(c->path));
else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
return -1;
c->host_port = ntohs(dest_port);
debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
c->self, c->path, c->host_port, s5_req.command);
s5_rsp.version = 0x05;
s5_rsp.command = SSH_SOCKS5_SUCCESS;
s5_rsp.reserved = 0; /* ignored */
s5_rsp.atyp = SSH_SOCKS5_IPV4;
((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
dest_port = 0; /* ignored */
buffer_append(&c->output, (char *)&s5_rsp, sizeof(s5_rsp));
buffer_append(&c->output, (char *)&dest_addr, sizeof(struct in_addr));
buffer_append(&c->output, (char *)&dest_port, sizeof(dest_port));
return 1;
}
/* dynamic port forwarding */
static void
channel_pre_dynamic(Channel *c, fd_set * readset, fd_set * writeset)
{
u_char *p;
int have, ret;
have = buffer_len(&c->input);
c->delayed = 0;
debug2("channel %d: pre_dynamic: have %d", c->self, have);
/* buffer_dump(&c->input); */
/* check if the fixed size part of the packet is in buffer. */
if (have < 3) {
/* need more */
FD_SET(c->sock, readset);
return;
}
/* try to guess the protocol */
p = buffer_ptr(&c->input);
switch (p[0]) {
case 0x04:
ret = channel_decode_socks4(c, readset, writeset);
break;
case 0x05:
ret = channel_decode_socks5(c, readset, writeset);
break;
default:
ret = -1;
break;
}
if (ret < 0) {
chan_mark_dead(c);
} else if (ret == 0) {
debug2("channel %d: pre_dynamic: need more", c->self);
/* need more */
FD_SET(c->sock, readset);
} else {
/* switch to the next state */
c->type = SSH_CHANNEL_OPENING;
port_open_helper(c, "direct-tcpip");
}
}
/* This is our fake X11 server socket. */
static void
channel_post_x11_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
Channel *nc;
struct sockaddr addr;
int newsock;
socklen_t addrlen;
char buf[16384], *remote_ipaddr;
int remote_port;
if (FD_ISSET(c->sock, readset)) {
debug("X11 connection requested.");
addrlen = sizeof(addr);
newsock = accept(c->sock, &addr, &addrlen);
if (c->single_connection) {
debug2("single_connection: closing X11 listener.");
channel_close_fd(&c->sock);
chan_mark_dead(c);
}
if (newsock < 0) {
error("accept: %.100s", strerror(errno));
return;
}
set_nodelay(newsock);
remote_ipaddr = get_peer_ipaddr(newsock);
remote_port = get_peer_port(newsock);
snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
remote_ipaddr, remote_port);
nc = channel_new("accepted x11 socket",
SSH_CHANNEL_OPENING, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket, 0, buf, 1);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring("x11");
packet_put_int(nc->self);
packet_put_int(nc->local_window_max);
packet_put_int(nc->local_maxpacket);
/* originator ipaddr and port */
packet_put_cstring(remote_ipaddr);
if (datafellows & SSH_BUG_X11FWD) {
debug2("ssh2 x11 bug compat mode");
} else {
packet_put_int(remote_port);
}
packet_send();
} else {
packet_start(SSH_SMSG_X11_OPEN);
packet_put_int(nc->self);
if (packet_get_protocol_flags() &
SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
packet_put_cstring(buf);
packet_send();
}
xfree(remote_ipaddr);
}
}
static void
port_open_helper(Channel *c, char *rtype)
{
int direct;
char buf[1024];
char *remote_ipaddr = get_peer_ipaddr(c->sock);
u_short remote_port = get_peer_port(c->sock);
direct = (strcmp(rtype, "direct-tcpip") == 0);
snprintf(buf, sizeof buf,
"%s: listening port %d for %.100s port %d, "
"connect from %.200s port %d",
rtype, c->listening_port, c->path, c->host_port,
remote_ipaddr, remote_port);
xfree(c->remote_name);
c->remote_name = xstrdup(buf);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring(rtype);
packet_put_int(c->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
if (direct) {
/* target host, port */
packet_put_cstring(c->path);
packet_put_int(c->host_port);
} else {
/* listen address, port */
packet_put_cstring(c->path);
packet_put_int(c->listening_port);
}
/* originator host and port */
packet_put_cstring(remote_ipaddr);
packet_put_int(remote_port);
packet_send();
} else {
packet_start(SSH_MSG_PORT_OPEN);
packet_put_int(c->self);
packet_put_cstring(c->path);
packet_put_int(c->host_port);
if (packet_get_protocol_flags() &
SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
packet_put_cstring(c->remote_name);
packet_send();
}
xfree(remote_ipaddr);
}
/*
* This socket is listening for connections to a forwarded TCP/IP port.
*/
static void
channel_post_port_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
Channel *nc;
struct sockaddr addr;
int newsock, nextstate;
socklen_t addrlen;
char *rtype;
if (FD_ISSET(c->sock, readset)) {
debug("Connection to port %d forwarding "
"to %.100s port %d requested.",
c->listening_port, c->path, c->host_port);
if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "forwarded-tcpip";
} else {
if (c->host_port == 0) {
nextstate = SSH_CHANNEL_DYNAMIC;
rtype = "dynamic-tcpip";
} else {
nextstate = SSH_CHANNEL_OPENING;
rtype = "direct-tcpip";
}
}
addrlen = sizeof(addr);
newsock = accept(c->sock, &addr, &addrlen);
if (newsock < 0) {
error("accept: %.100s", strerror(errno));
return;
}
set_nodelay(newsock);
nc = channel_new(rtype, nextstate, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket, 0, rtype, 1);
nc->listening_port = c->listening_port;
nc->host_port = c->host_port;
strlcpy(nc->path, c->path, sizeof(nc->path));
if (nextstate == SSH_CHANNEL_DYNAMIC) {
/*
* do not call the channel_post handler until
* this flag has been reset by a pre-handler.
* otherwise the FD_ISSET calls might overflow
*/
nc->delayed = 1;
} else {
port_open_helper(nc, rtype);
}
}
}
/*
* This is the authentication agent socket listening for connections from
* clients.
*/
static void
channel_post_auth_listener(Channel *c, fd_set * readset, fd_set * writeset)
{
Channel *nc;
int newsock;
struct sockaddr addr;
socklen_t addrlen;
if (FD_ISSET(c->sock, readset)) {
addrlen = sizeof(addr);
newsock = accept(c->sock, &addr, &addrlen);
if (newsock < 0) {
error("accept from auth socket: %.100s", strerror(errno));
return;
}
nc = channel_new("accepted auth socket",
SSH_CHANNEL_OPENING, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket,
0, "accepted auth socket", 1);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring("auth-agent@openssh.com");
packet_put_int(nc->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
} else {
packet_start(SSH_SMSG_AGENT_OPEN);
packet_put_int(nc->self);
}
packet_send();
}
}
static void
channel_post_connecting(Channel *c, fd_set * readset, fd_set * writeset)
{
int err = 0;
socklen_t sz = sizeof(err);
if (FD_ISSET(c->sock, writeset)) {
if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
err = errno;
error("getsockopt SO_ERROR failed");
}
if (err == 0) {
debug("channel %d: connected", c->self);
c->type = SSH_CHANNEL_OPEN;
if (compat20) {
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);
} else {
packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(c->remote_id);
packet_put_int(c->self);
}
} else {
debug("channel %d: not connected: %s",
c->self, strerror(err));
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(c->remote_id);
packet_put_int(SSH2_OPEN_CONNECT_FAILED);
if (!(datafellows & SSH_BUG_OPENFAILURE)) {
packet_put_cstring(strerror(err));
packet_put_cstring("");
}
} else {
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(c->remote_id);
}
chan_mark_dead(c);
}
packet_send();
}
}
static int
channel_handle_rfd(Channel *c, fd_set * readset, fd_set * writeset)
{
char buf[16*1024];
int len;
if (c->rfd != -1 &&
FD_ISSET(c->rfd, readset)) {
len = read(c->rfd, buf, sizeof(buf));
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return 1;
if (len <= 0) {
debug2("channel %d: read<=0 rfd %d len %d",
c->self, c->rfd, len);
if (c->type != SSH_CHANNEL_OPEN) {
debug2("channel %d: not open", c->self);
chan_mark_dead(c);
return -1;
} else if (compat13) {
buffer_clear(&c->output);
c->type = SSH_CHANNEL_INPUT_DRAINING;
debug2("channel %d: input draining.", c->self);
} else {
chan_read_failed(c);
}
return -1;
}
if (c->input_filter != NULL) {
if (c->input_filter(c, buf, len) == -1) {
debug2("channel %d: filter stops", c->self);
chan_read_failed(c);
}
} else {
buffer_append(&c->input, buf, len);
}
}
return 1;
}
static int
channel_handle_wfd(Channel *c, fd_set * readset, fd_set * writeset)
{
struct termios tio;
u_char *data;
u_int dlen;
int len;
/* Send buffered output data to the socket. */
if (c->wfd != -1 &&
FD_ISSET(c->wfd, writeset) &&
buffer_len(&c->output) > 0) {
data = buffer_ptr(&c->output);
dlen = buffer_len(&c->output);
#ifdef _AIX
/* XXX: Later AIX versions can't push as much data to tty */
if (compat20 && c->wfd_isatty && dlen > 8*1024)
dlen = 8*1024;
#endif
len = write(c->wfd, data, dlen);
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return 1;
if (len <= 0) {
if (c->type != SSH_CHANNEL_OPEN) {
debug2("channel %d: not open", c->self);
chan_mark_dead(c);
return -1;
} else if (compat13) {
buffer_clear(&c->output);
debug2("channel %d: input draining.", c->self);
c->type = SSH_CHANNEL_INPUT_DRAINING;
} else {
chan_write_failed(c);
}
return -1;
}
if (compat20 && c->isatty && dlen >= 1 && data[0] != '\r') {
if (tcgetattr(c->wfd, &tio) == 0 &&
!(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
/*
* Simulate echo to reduce the impact of
* traffic analysis. We need to match the
* size of a SSH2_MSG_CHANNEL_DATA message
* (4 byte channel id + data)
*/
packet_send_ignore(4 + len);
packet_send();
}
}
buffer_consume(&c->output, len);
if (compat20 && len > 0) {
c->local_consumed += len;
}
}
return 1;
}
static int
channel_handle_efd(Channel *c, fd_set * readset, fd_set * writeset)
{
char buf[16*1024];
int len;
/** XXX handle drain efd, too */
if (c->efd != -1) {
if (c->extended_usage == CHAN_EXTENDED_WRITE &&
FD_ISSET(c->efd, writeset) &&
buffer_len(&c->extended) > 0) {
len = write(c->efd, buffer_ptr(&c->extended),
buffer_len(&c->extended));
debug2("channel %d: written %d to efd %d",
c->self, len, c->efd);
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return 1;
if (len <= 0) {
debug2("channel %d: closing write-efd %d",
c->self, c->efd);
channel_close_fd(&c->efd);
} else {
buffer_consume(&c->extended, len);
c->local_consumed += len;
}
} else if (c->extended_usage == CHAN_EXTENDED_READ &&
FD_ISSET(c->efd, readset)) {
len = read(c->efd, buf, sizeof(buf));
debug2("channel %d: read %d from efd %d",
c->self, len, c->efd);
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return 1;
if (len <= 0) {
debug2("channel %d: closing read-efd %d",
c->self, c->efd);
channel_close_fd(&c->efd);
} else {
buffer_append(&c->extended, buf, len);
}
}
}
return 1;
}
static int
channel_check_window(Channel *c)
{
if (c->type == SSH_CHANNEL_OPEN &&
!(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
c->local_window < c->local_window_max/2 &&
c->local_consumed > 0) {
packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
packet_put_int(c->remote_id);
packet_put_int(c->local_consumed);
packet_send();
debug2("channel %d: window %d sent adjust %d",
c->self, c->local_window,
c->local_consumed);
c->local_window += c->local_consumed;
c->local_consumed = 0;
}
return 1;
}
static void
channel_post_open(Channel *c, fd_set * readset, fd_set * writeset)
{
if (c->delayed)
return;
channel_handle_rfd(c, readset, writeset);
channel_handle_wfd(c, readset, writeset);
if (!compat20)
return;
channel_handle_efd(c, readset, writeset);
channel_check_window(c);
}
static void
channel_post_output_drain_13(Channel *c, fd_set * readset, fd_set * writeset)
{
int len;
/* Send buffered output data to the socket. */
if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
len = write(c->sock, buffer_ptr(&c->output),
buffer_len(&c->output));
if (len <= 0)
buffer_clear(&c->output);
else
buffer_consume(&c->output, len);
}
}
static void
channel_handler_init_20(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_RPORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
}
static void
channel_handler_init_13(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_13;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open_13;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_INPUT_DRAINING] = &channel_pre_input_draining;
channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_pre_output_draining;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
channel_post[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_post_output_drain_13;
channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
}
static void
channel_handler_init_15(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
}
static void
channel_handler_init(void)
{
int i;
for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
channel_pre[i] = NULL;
channel_post[i] = NULL;
}
if (compat20)
channel_handler_init_20();
else if (compat13)
channel_handler_init_13();
else
channel_handler_init_15();
}
/* gc dead channels */
static void
channel_garbage_collect(Channel *c)
{
if (c == NULL)
return;
if (c->detach_user != NULL) {
if (!chan_is_dead(c, 0))
return;
debug2("channel %d: gc: notify user", c->self);
c->detach_user(c->self, NULL);
/* if we still have a callback */
if (c->detach_user != NULL)
return;
debug2("channel %d: gc: user detached", c->self);
}
if (!chan_is_dead(c, 1))
return;
debug2("channel %d: garbage collecting", c->self);
channel_free(c);
}
static void
channel_handler(chan_fn *ftab[], fd_set * readset, fd_set * writeset)
{
static int did_init = 0;
int i;
Channel *c;
if (!did_init) {
channel_handler_init();
did_init = 1;
}
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL)
continue;
if (ftab[c->type] != NULL)
(*ftab[c->type])(c, readset, writeset);
channel_garbage_collect(c);
}
}
/*
* Allocate/update select bitmasks and add any bits relevant to channels in
* select bitmasks.
*/
void
channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
int *nallocp, int rekeying)
{
int n;
u_int sz;
n = MAX(*maxfdp, channel_max_fd);
sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
/* perhaps check sz < nalloc/2 and shrink? */
if (*readsetp == NULL || sz > *nallocp) {
*readsetp = xrealloc(*readsetp, sz);
*writesetp = xrealloc(*writesetp, sz);
*nallocp = sz;
}
*maxfdp = n;
memset(*readsetp, 0, sz);
memset(*writesetp, 0, sz);
if (!rekeying)
channel_handler(channel_pre, *readsetp, *writesetp);
}
/*
* After select, perform any appropriate operations for channels which have
* events pending.
*/
void
channel_after_select(fd_set * readset, fd_set * writeset)
{
channel_handler(channel_post, readset, writeset);
}
/* If there is data to send to the connection, enqueue some of it now. */
void
channel_output_poll(void)
{
Channel *c;
int i;
u_int len;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL)
continue;
/*
* We are only interested in channels that can have buffered
* incoming data.
*/
if (compat13) {
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_INPUT_DRAINING)
continue;
} else {
if (c->type != SSH_CHANNEL_OPEN)
continue;
}
if (compat20 &&
(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
/* XXX is this true? */
debug3("channel %d: will not send data after close", c->self);
continue;
}
/* Get the amount of buffered data for this channel. */
if ((c->istate == CHAN_INPUT_OPEN ||
c->istate == CHAN_INPUT_WAIT_DRAIN) &&
(len = buffer_len(&c->input)) > 0) {
/*
* Send some data for the other side over the secure
* connection.
*/
if (compat20) {
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
} else {
if (packet_is_interactive()) {
if (len > 1024)
len = 512;
} else {
/* Keep the packets at reasonable size. */
if (len > packet_get_maxsize()/2)
len = packet_get_maxsize()/2;
}
}
if (len > 0) {
packet_start(compat20 ?
SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
packet_put_int(c->remote_id);
packet_put_string(buffer_ptr(&c->input), len);
packet_send();
buffer_consume(&c->input, len);
c->remote_window -= len;
}
} else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
if (compat13)
fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
/*
* input-buffer is empty and read-socket shutdown:
* tell peer, that we will not send more data: send IEOF.
* hack for extended data: delay EOF if EFD still in use.
*/
if (CHANNEL_EFD_INPUT_ACTIVE(c))
debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
c->self, c->efd, buffer_len(&c->extended));
else
chan_ibuf_empty(c);
}
/* Send extended data, i.e. stderr */
if (compat20 &&
!(c->flags & CHAN_EOF_SENT) &&
c->remote_window > 0 &&
(len = buffer_len(&c->extended)) > 0 &&
c->extended_usage == CHAN_EXTENDED_READ) {
debug2("channel %d: rwin %u elen %u euse %d",
c->self, c->remote_window, buffer_len(&c->extended),
c->extended_usage);
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
packet_put_int(c->remote_id);
packet_put_int(SSH2_EXTENDED_DATA_STDERR);
packet_put_string(buffer_ptr(&c->extended), len);
packet_send();
buffer_consume(&c->extended, len);
c->remote_window -= len;
debug2("channel %d: sent ext data %d", c->self, len);
}
}
}
/* -- protocol input */
void
channel_input_data(int type, u_int32_t seq, void *ctxt)
{
int id;
char *data;
u_int data_len;
Channel *c;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received data for nonexistent channel %d.", id);
/* Ignore any data for non-open channels (might happen on close) */
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_X11_OPEN)
return;
/* same for protocol 1.5 if output end is no longer open */
if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN)
return;
/* Get the data. */
data = packet_get_string(&data_len);
if (compat20) {
if (data_len > c->local_maxpacket) {
logit("channel %d: rcvd big packet %d, maxpack %d",
c->self, data_len, c->local_maxpacket);
}
if (data_len > c->local_window) {
logit("channel %d: rcvd too much data %d, win %d",
c->self, data_len, c->local_window);
xfree(data);
return;
}
c->local_window -= data_len;
}
packet_check_eom();
buffer_append(&c->output, data, data_len);
xfree(data);
}
void
channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
{
int id;
char *data;
u_int data_len, tcode;
Channel *c;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received extended_data for bad channel %d.", id);
if (c->type != SSH_CHANNEL_OPEN) {
logit("channel %d: ext data for non open", id);
return;
}
if (c->flags & CHAN_EOF_RCVD) {
if (datafellows & SSH_BUG_EXTEOF)
debug("channel %d: accepting ext data after eof", id);
else
packet_disconnect("Received extended_data after EOF "
"on channel %d.", id);
}
tcode = packet_get_int();
if (c->efd == -1 ||
c->extended_usage != CHAN_EXTENDED_WRITE ||
tcode != SSH2_EXTENDED_DATA_STDERR) {
logit("channel %d: bad ext data", c->self);
return;
}
data = packet_get_string(&data_len);
packet_check_eom();
if (data_len > c->local_window) {
logit("channel %d: rcvd too much extended_data %d, win %d",
c->self, data_len, c->local_window);
xfree(data);
return;
}
debug2("channel %d: rcvd ext data %d", c->self, data_len);
c->local_window -= data_len;
buffer_append(&c->extended, data, data_len);
xfree(data);
}
void
channel_input_ieof(int type, u_int32_t seq, void *ctxt)
{
int id;
Channel *c;
id = packet_get_int();
packet_check_eom();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received ieof for nonexistent channel %d.", id);
chan_rcvd_ieof(c);
/* XXX force input close */
if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
debug("channel %d: FORCE input drain", c->self);
c->istate = CHAN_INPUT_WAIT_DRAIN;
if (buffer_len(&c->input) == 0)
chan_ibuf_empty(c);
}
}
void
channel_input_close(int type, u_int32_t seq, void *ctxt)
{
int id;
Channel *c;
id = packet_get_int();
packet_check_eom();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received close for nonexistent channel %d.", id);
/*
* Send a confirmation that we have closed the channel and no more
* data is coming for it.
*/
packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
packet_put_int(c->remote_id);
packet_send();
/*
* If the channel is in closed state, we have sent a close request,
* and the other side will eventually respond with a confirmation.
* Thus, we cannot free the channel here, because then there would be
* no-one to receive the confirmation. The channel gets freed when
* the confirmation arrives.
*/
if (c->type != SSH_CHANNEL_CLOSED) {
/*
* Not a closed channel - mark it as draining, which will
* cause it to be freed later.
*/
buffer_clear(&c->input);
c->type = SSH_CHANNEL_OUTPUT_DRAINING;
}
}
/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
void
channel_input_oclose(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
packet_check_eom();
if (c == NULL)
packet_disconnect("Received oclose for nonexistent channel %d.", id);
chan_rcvd_oclose(c);
}
void
channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
packet_check_eom();
if (c == NULL)
packet_disconnect("Received close confirmation for "
"out-of-range channel %d.", id);
if (c->type != SSH_CHANNEL_CLOSED)
packet_disconnect("Received close confirmation for "
"non-closed channel %d (type %d).", id, c->type);
channel_free(c);
}
void
channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
{
int id, remote_id;
Channel *c;
id = packet_get_int();
c = channel_lookup(id);
if (c==NULL || c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open confirmation for "
"non-opening channel %d.", id);
remote_id = packet_get_int();
/* Record the remote channel number and mark that the channel is now open. */
c->remote_id = remote_id;
c->type = SSH_CHANNEL_OPEN;
if (compat20) {
c->remote_window = packet_get_int();
c->remote_maxpacket = packet_get_int();
if (c->confirm) {
debug2("callback start");
c->confirm(c->self, NULL);
debug2("callback done");
}
debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
c->remote_window, c->remote_maxpacket);
}
packet_check_eom();
}
static char *
reason2txt(int reason)
{
switch (reason) {
case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
return "administratively prohibited";
case SSH2_OPEN_CONNECT_FAILED:
return "connect failed";
case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
return "unknown channel type";
case SSH2_OPEN_RESOURCE_SHORTAGE:
return "resource shortage";
}
return "unknown reason";
}
void
channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
{
int id, reason;
char *msg = NULL, *lang = NULL;
Channel *c;
id = packet_get_int();
c = channel_lookup(id);
if (c==NULL || c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open failure for "
"non-opening channel %d.", id);
if (compat20) {
reason = packet_get_int();
if (!(datafellows & SSH_BUG_OPENFAILURE)) {
msg = packet_get_string(NULL);
lang = packet_get_string(NULL);
}
logit("channel %d: open failed: %s%s%s", id,
reason2txt(reason), msg ? ": ": "", msg ? msg : "");
if (msg != NULL)
xfree(msg);
if (lang != NULL)
xfree(lang);
}
packet_check_eom();
/* Free the channel. This will also close the socket. */
channel_free(c);
}
void
channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
{
Channel *c;
int id;
u_int adjust;
if (!compat20)
return;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL || c->type != SSH_CHANNEL_OPEN) {
logit("Received window adjust for "
"non-open channel %d.", id);
return;
}
adjust = packet_get_int();
packet_check_eom();
debug2("channel %d: rcvd adjust %u", id, adjust);
c->remote_window += adjust;
}
void
channel_input_port_open(int type, u_int32_t seq, void *ctxt)
{
Channel *c = NULL;
u_short host_port;
char *host, *originator_string;
int remote_id, sock = -1;
remote_id = packet_get_int();
host = packet_get_string(NULL);
host_port = packet_get_int();
if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
originator_string = packet_get_string(NULL);
} else {
originator_string = xstrdup("unknown (remote did not supply name)");
}
packet_check_eom();
sock = channel_connect_to(host, host_port);
if (sock != -1) {
c = channel_new("connected socket",
SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
originator_string, 1);
c->remote_id = remote_id;
}
xfree(originator_string);
if (c == NULL) {
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(remote_id);
packet_send();
}
xfree(host);
}
/* -- tcp forwarding */
void
channel_set_af(int af)
{
IPv4or6 = af;
}
static int
channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
const char *host_to_connect, u_short port_to_connect, int gateway_ports)
{
Channel *c;
int success, sock, on = 1;
struct addrinfo hints, *ai, *aitop;
const char *host;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
success = 0;
host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
listen_addr : host_to_connect;
if (host == NULL) {
error("No forward host name.");
return success;
}
if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
error("Forward host name too long.");
return success;
}
/*
* getaddrinfo returns a loopback address if the hostname is
* set to NULL and hints.ai_flags is not AI_PASSIVE
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_flags = gateway_ports ? AI_PASSIVE : 0;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", listen_port);
if (getaddrinfo(NULL, strport, &hints, &aitop) != 0)
packet_disconnect("getaddrinfo: fatal error");
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("channel_setup_fwd_listener: getnameinfo failed");
continue;
}
/* Create a port to listen for the host. */
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0) {
/* this is no error since kernel may not support ipv6 */
verbose("socket: %.100s", strerror(errno));
continue;
}
/*
* Set socket options.
* Allow local port reuse in TIME_WAIT.
*/
if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on,
sizeof(on)) == -1)
error("setsockopt SO_REUSEADDR: %s", strerror(errno));
debug("Local forwarding listening on %s port %s.", ntop, strport);
/* Bind the socket to the address. */
if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
/* address can be in use ipv6 address is already bound */
if (!ai->ai_next)
error("bind: %.100s", strerror(errno));
else
verbose("bind: %.100s", strerror(errno));
close(sock);
continue;
}
/* Start listening for connections on the socket. */
if (listen(sock, 5) < 0) {
error("listen: %.100s", strerror(errno));
close(sock);
continue;
}
/* Allocate a channel number for the socket. */
c = channel_new("port listener", type, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, "port listener", 1);
strlcpy(c->path, host, sizeof(c->path));
c->host_port = port_to_connect;
c->listening_port = listen_port;
success = 1;
}
if (success == 0)
error("channel_setup_fwd_listener: cannot listen to port: %d",
listen_port);
freeaddrinfo(aitop);
return success;
}
/* protocol local port fwd, used by ssh (and sshd in v1) */
int
channel_setup_local_fwd_listener(u_short listen_port,
const char *host_to_connect, u_short port_to_connect, int gateway_ports)
{
return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
NULL, listen_port, host_to_connect, port_to_connect, gateway_ports);
}
/* protocol v2 remote port fwd, used by sshd */
int
channel_setup_remote_fwd_listener(const char *listen_address,
u_short listen_port, int gateway_ports)
{
return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
listen_address, listen_port, NULL, 0, gateway_ports);
}
/*
* Initiate forwarding of connections to port "port" on remote host through
* the secure channel to host:port from local side.
*/
void
channel_request_remote_forwarding(u_short listen_port,
const char *host_to_connect, u_short port_to_connect)
{
int type, success = 0;
/* Record locally that connection to this host/port is permitted. */
if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
fatal("channel_request_remote_forwarding: too many forwards");
/* Send the forward request to the remote side. */
if (compat20) {
const char *address_to_bind = "0.0.0.0";
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("tcpip-forward");
packet_put_char(1); /* boolean: want reply */
packet_put_cstring(address_to_bind);
packet_put_int(listen_port);
packet_send();
packet_write_wait();
/* Assume that server accepts the request */
success = 1;
} else {
packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
packet_put_int(listen_port);
packet_put_cstring(host_to_connect);
packet_put_int(port_to_connect);
packet_send();
packet_write_wait();
/* Wait for response from the remote side. */
type = packet_read();
switch (type) {
case SSH_SMSG_SUCCESS:
success = 1;
break;
case SSH_SMSG_FAILURE:
logit("Warning: Server denied remote port forwarding.");
break;
default:
/* Unknown packet */
packet_disconnect("Protocol error for port forward request:"
"received packet type %d.", type);
}
}
if (success) {
permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
permitted_opens[num_permitted_opens].listen_port = listen_port;
num_permitted_opens++;
}
}
/*
* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
* listening for the port, and sends back a success reply (or disconnect
* message if there was an error). This never returns if there was an error.
*/
void
channel_input_port_forward_request(int is_root, int gateway_ports)
{
u_short port, host_port;
char *hostname;
/* Get arguments from the packet. */
port = packet_get_int();
hostname = packet_get_string(NULL);
host_port = packet_get_int();
#ifndef HAVE_CYGWIN
/*
* Check that an unprivileged user is not trying to forward a
* privileged port.
*/
if (port < IPPORT_RESERVED && !is_root)
packet_disconnect(
"Requested forwarding of port %d but user is not root.",
port);
if (host_port == 0)
packet_disconnect("Dynamic forwarding denied.");
#endif
/* Initiate forwarding */
channel_setup_local_fwd_listener(port, hostname, host_port, gateway_ports);
/* Free the argument string. */
xfree(hostname);
}
/*
* Permits opening to any host/port if permitted_opens[] is empty. This is
* usually called by the server, because the user could connect to any port
* anyway, and the server has no way to know but to trust the client anyway.
*/
void
channel_permit_all_opens(void)
{
if (num_permitted_opens == 0)
all_opens_permitted = 1;
}
void
channel_add_permitted_opens(char *host, int port)
{
if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
fatal("channel_request_remote_forwarding: too many forwards");
debug("allow port forwarding to host %s port %d", host, port);
permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
permitted_opens[num_permitted_opens].port_to_connect = port;
num_permitted_opens++;
all_opens_permitted = 0;
}
void
channel_clear_permitted_opens(void)
{
int i;
for (i = 0; i < num_permitted_opens; i++)
xfree(permitted_opens[i].host_to_connect);
num_permitted_opens = 0;
}
/* return socket to remote host, port */
static int
connect_to(const char *host, u_short port)
{
struct addrinfo hints, *ai, *aitop;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
int gaierr;
int sock = -1;
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
error("connect_to %.100s: unknown host (%s)", host,
gai_strerror(gaierr));
return -1;
}
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("connect_to: getnameinfo failed");
continue;
}
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0) {
if (ai->ai_next == NULL)
error("socket: %.100s", strerror(errno));
else
verbose("socket: %.100s", strerror(errno));
continue;
}
if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0)
fatal("connect_to: F_SETFL: %s", strerror(errno));
if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
errno != EINPROGRESS) {
error("connect_to %.100s port %s: %.100s", ntop, strport,
strerror(errno));
close(sock);
continue; /* fail -- try next */
}
break; /* success */
}
freeaddrinfo(aitop);
if (!ai) {
error("connect_to %.100s port %d: failed.", host, port);
return -1;
}
/* success */
set_nodelay(sock);
return sock;
}
int
channel_connect_by_listen_address(u_short listen_port)
{
int i;
for (i = 0; i < num_permitted_opens; i++)
if (permitted_opens[i].listen_port == listen_port)
return connect_to(
permitted_opens[i].host_to_connect,
permitted_opens[i].port_to_connect);
error("WARNING: Server requests forwarding for unknown listen_port %d",
listen_port);
return -1;
}
/* Check if connecting to that port is permitted and connect. */
int
channel_connect_to(const char *host, u_short port)
{
int i, permit;
permit = all_opens_permitted;
if (!permit) {
for (i = 0; i < num_permitted_opens; i++)
if (permitted_opens[i].port_to_connect == port &&
strcmp(permitted_opens[i].host_to_connect, host) == 0)
permit = 1;
}
if (!permit) {
logit("Received request to connect to host %.100s port %d, "
"but the request was denied.", host, port);
return -1;
}
return connect_to(host, port);
}
/* -- X11 forwarding */
/*
* Creates an internet domain socket for listening for X11 connections.
* Returns 0 and a suitable display number for the DISPLAY variable
* stored in display_numberp , or -1 if an error occurs.
*/
int
x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
int single_connection, u_int *display_numberp)
{
Channel *nc = NULL;
int display_number, sock;
u_short port;
struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV];
int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
for (display_number = x11_display_offset;
display_number < MAX_DISPLAYS;
display_number++) {
port = 6000 + display_number;
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
error("getaddrinfo: %.100s", gai_strerror(gaierr));
return -1;
}
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
sock = socket(ai->ai_family, ai->ai_socktype,
ai->ai_protocol);
if (sock < 0) {
if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
error("socket: %.100s", strerror(errno));
return -1;
} else {
debug("x11_create_display_inet: Socket family %d not supported",
ai->ai_family);
continue;
}
}
#ifdef IPV6_V6ONLY
if (ai->ai_family == AF_INET6) {
int on = 1;
if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
}
#endif
if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
debug2("bind port %d: %.100s", port, strerror(errno));
close(sock);
if (ai->ai_next)
continue;
for (n = 0; n < num_socks; n++) {
close(socks[n]);
}
num_socks = 0;
break;
}
socks[num_socks++] = sock;
#ifndef DONT_TRY_OTHER_AF
if (num_socks == NUM_SOCKS)
break;
#else
if (x11_use_localhost) {
if (num_socks == NUM_SOCKS)
break;
} else {
break;
}
#endif
}
freeaddrinfo(aitop);
if (num_socks > 0)
break;
}
if (display_number >= MAX_DISPLAYS) {
error("Failed to allocate internet-domain X11 display socket.");
return -1;
}
/* Start listening for connections on the socket. */
for (n = 0; n < num_socks; n++) {
sock = socks[n];
if (listen(sock, 5) < 0) {
error("listen: %.100s", strerror(errno));
close(sock);
return -1;
}
}
/* Allocate a channel for each socket. */
for (n = 0; n < num_socks; n++) {
sock = socks[n];
nc = channel_new("x11 listener",
SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
0, "X11 inet listener", 1);
nc->single_connection = single_connection;
}
/* Return the display number for the DISPLAY environment variable. */
*display_numberp = display_number;
return (0);
}
static int
connect_local_xsocket(u_int dnr)
{
int sock;
struct sockaddr_un addr;
sock = socket(AF_UNIX, SOCK_STREAM, 0);
if (sock < 0)
error("socket: %.100s", strerror(errno));
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
if (connect(sock, (struct sockaddr *) & addr, sizeof(addr)) == 0)
return sock;
close(sock);
error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
return -1;
}
int
x11_connect_display(void)
{
int display_number, sock = 0;
const char *display;
char buf[1024], *cp;
struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV];
int gaierr;
/* Try to open a socket for the local X server. */
display = getenv("DISPLAY");
if (!display) {
error("DISPLAY not set.");
return -1;
}
/*
* Now we decode the value of the DISPLAY variable and make a
* connection to the real X server.
*/
/*
* Check if it is a unix domain socket. Unix domain displays are in
* one of the following formats: unix:d[.s], :d[.s], ::d[.s]
*/
if (strncmp(display, "unix:", 5) == 0 ||
display[0] == ':') {
/* Connect to the unix domain socket. */
if (sscanf(strrchr(display, ':') + 1, "%d", &display_number) != 1) {
error("Could not parse display number from DISPLAY: %.100s",
display);
return -1;
}
/* Create a socket. */
sock = connect_local_xsocket(display_number);
if (sock < 0)
return -1;
/* OK, we now have a connection to the display. */
return sock;
}
/*
* Connect to an inet socket. The DISPLAY value is supposedly
* hostname:d[.s], where hostname may also be numeric IP address.
*/
strlcpy(buf, display, sizeof(buf));
cp = strchr(buf, ':');
if (!cp) {
error("Could not find ':' in DISPLAY: %.100s", display);
return -1;
}
*cp = 0;
/* buf now contains the host name. But first we parse the display number. */
if (sscanf(cp + 1, "%d", &display_number) != 1) {
error("Could not parse display number from DISPLAY: %.100s",
display);
return -1;
}
/* Look up the host address */
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", 6000 + display_number);
if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
return -1;
}
for (ai = aitop; ai; ai = ai->ai_next) {
/* Create a socket. */
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0) {
debug2("socket: %.100s", strerror(errno));
continue;
}
/* Connect it to the display. */
if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
debug2("connect %.100s port %d: %.100s", buf,
6000 + display_number, strerror(errno));
close(sock);
continue;
}
/* Success */
break;
}
freeaddrinfo(aitop);
if (!ai) {
error("connect %.100s port %d: %.100s", buf, 6000 + display_number,
strerror(errno));
return -1;
}
set_nodelay(sock);
return sock;
}
/*
* This is called when SSH_SMSG_X11_OPEN is received. The packet contains
* the remote channel number. We should do whatever we want, and respond
* with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
*/
void
x11_input_open(int type, u_int32_t seq, void *ctxt)
{
Channel *c = NULL;
int remote_id, sock = 0;
char *remote_host;
debug("Received X11 open request.");
remote_id = packet_get_int();
if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
remote_host = packet_get_string(NULL);
} else {
remote_host = xstrdup("unknown (remote did not supply name)");
}
packet_check_eom();
/* Obtain a connection to the real X display. */
sock = x11_connect_display();
if (sock != -1) {
/* Allocate a channel for this connection. */
c = channel_new("connected x11 socket",
SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
remote_host, 1);
c->remote_id = remote_id;
c->force_drain = 1;
}
xfree(remote_host);
if (c == NULL) {
/* Send refusal to the remote host. */
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(remote_id);
} else {
/* Send a confirmation to the remote host. */
packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(remote_id);
packet_put_int(c->self);
}
packet_send();
}
/* dummy protocol handler that denies SSH-1 requests (agent/x11) */
void
deny_input_open(int type, u_int32_t seq, void *ctxt)
{
int rchan = packet_get_int();
switch (type) {
case SSH_SMSG_AGENT_OPEN:
error("Warning: ssh server tried agent forwarding.");
break;
case SSH_SMSG_X11_OPEN:
error("Warning: ssh server tried X11 forwarding.");
break;
default:
error("deny_input_open: type %d", type);
break;
}
error("Warning: this is probably a break in attempt by a malicious server.");
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(rchan);
packet_send();
}
/*
* Requests forwarding of X11 connections, generates fake authentication
* data, and enables authentication spoofing.
* This should be called in the client only.
*/
void
x11_request_forwarding_with_spoofing(int client_session_id,
const char *proto, const char *data)
{
u_int data_len = (u_int) strlen(data) / 2;
u_int i, value, len;
char *new_data;
int screen_number;
const char *cp;
u_int32_t rand = 0;
cp = getenv("DISPLAY");
if (cp)
cp = strchr(cp, ':');
if (cp)
cp = strchr(cp, '.');
if (cp)
screen_number = atoi(cp + 1);
else
screen_number = 0;
/* Save protocol name. */
x11_saved_proto = xstrdup(proto);
/*
* Extract real authentication data and generate fake data of the
* same length.
*/
x11_saved_data = xmalloc(data_len);
x11_fake_data = xmalloc(data_len);
for (i = 0; i < data_len; i++) {
if (sscanf(data + 2 * i, "%2x", &value) != 1)
fatal("x11_request_forwarding: bad authentication data: %.100s", data);
if (i % 4 == 0)
rand = arc4random();
x11_saved_data[i] = value;
x11_fake_data[i] = rand & 0xff;
rand >>= 8;
}
x11_saved_data_len = data_len;
x11_fake_data_len = data_len;
/* Convert the fake data into hex. */
len = 2 * data_len + 1;
new_data = xmalloc(len);
for (i = 0; i < data_len; i++)
snprintf(new_data + 2 * i, len - 2 * i,
"%02x", (u_char) x11_fake_data[i]);
/* Send the request packet. */
if (compat20) {
channel_request_start(client_session_id, "x11-req", 0);
packet_put_char(0); /* XXX bool single connection */
} else {
packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
}
packet_put_cstring(proto);
packet_put_cstring(new_data);
packet_put_int(screen_number);
packet_send();
packet_write_wait();
xfree(new_data);
}
/* -- agent forwarding */
/* Sends a message to the server to request authentication fd forwarding. */
void
auth_request_forwarding(void)
{
packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
packet_send();
packet_write_wait();
}
/* This is called to process an SSH_SMSG_AGENT_OPEN message. */
void
auth_input_open_request(int type, u_int32_t seq, void *ctxt)
{
Channel *c = NULL;
int remote_id, sock;
/* Read the remote channel number from the message. */
remote_id = packet_get_int();
packet_check_eom();
/*
* Get a connection to the local authentication agent (this may again
* get forwarded).
*/
sock = ssh_get_authentication_socket();
/*
* If we could not connect the agent, send an error message back to
* the server. This should never happen unless the agent dies,
* because authentication forwarding is only enabled if we have an
* agent.
*/
if (sock >= 0) {
c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
-1, 0, 0, 0, "authentication agent connection", 1);
c->remote_id = remote_id;
c->force_drain = 1;
}
if (c == NULL) {
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(remote_id);
} else {
/* Send a confirmation to the remote host. */
debug("Forwarding authentication connection.");
packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(remote_id);
packet_put_int(c->self);
}
packet_send();
}
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