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/* $OpenBSD: channels.c,v 1.359 2017/04/30 23:28:41 djm Exp $ */
/*
* 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"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/un.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <stdarg.h>
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "ssherr.h"
#include "packet.h"
#include "log.h"
#include "misc.h"
#include "buffer.h"
#include "channels.h"
#include "compat.h"
#include "canohost.h"
#include "key.h"
#include "authfd.h"
#include "pathnames.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 u_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).
*/
/* XXX: streamlocal wants a path instead of host:port */
/* Overload host_to_connect; we could just make this match Forward */
/* XXX - can we use listen_host instead of listen_path? */
typedef struct {
char *host_to_connect; /* Connect to 'host'. */
int port_to_connect; /* Connect to 'port'. */
char *listen_host; /* Remote side should listen address. */
char *listen_path; /* Remote side should listen path. */
int listen_port; /* Remote side should listen port. */
Channel *downstream; /* Downstream mux*/
} ForwardPermission;
/* List of all permitted host/port pairs to connect by the user. */
static ForwardPermission *permitted_opens = NULL;
/* List of all permitted host/port pairs to connect by the admin. */
static ForwardPermission *permitted_adm_opens = NULL;
/* Number of permitted host/port pairs in the array permitted by the user. */
static int num_permitted_opens = 0;
/* Number of permitted host/port pair in the array permitted by the admin. */
static int num_adm_permitted_opens = 0;
/* special-case port number meaning allow any port */
#define FWD_PERMIT_ANY_PORT 0
/* special-case wildcard meaning allow any host */
#define FWD_PERMIT_ANY_HOST "*"
/*
* 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 local (client) display. */
static char *x11_saved_display = NULL;
/* 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;
/* Deadline after which all X11 connections are refused */
static u_int x11_refuse_time;
/*
* 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 u_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);
static const char *channel_rfwd_bind_host(const char *listen_host);
/* non-blocking connect helpers */
static int connect_next(struct channel_connect *);
static void channel_connect_ctx_free(struct channel_connect *);
/* -- channel core */
Channel *
channel_by_id(int id)
{
Channel *c;
if (id < 0 || (u_int)id >= channels_alloc) {
logit("channel_by_id: %d: bad id", id);
return NULL;
}
c = channels[id];
if (c == NULL) {
logit("channel_by_id: %d: bad id: channel free", id);
return NULL;
}
return c;
}
Channel *
channel_by_remote_id(int remote_id)
{
Channel *c;
u_int i;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL && c->remote_id == remote_id)
return c;
}
return NULL;
}
/*
* Returns the channel if it is allowed to receive protocol messages.
* Private channels, like listening sockets, may not receive messages.
*/
Channel *
channel_lookup(int id)
{
Channel *c;
if ((c = channel_by_id(id)) == NULL)
return (NULL);
switch (c->type) {
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_MUX_PROXY:
return (c);
}
logit("Non-public channel %d, type %d.", id, c->type);
return (NULL);
}
/*
* 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, int is_tty)
{
/* Update the maximum file descriptor value. */
channel_max_fd = MAXIMUM(channel_max_fd, rfd);
channel_max_fd = MAXIMUM(channel_max_fd, wfd);
channel_max_fd = MAXIMUM(channel_max_fd, efd);
if (rfd != -1)
fcntl(rfd, F_SETFD, FD_CLOEXEC);
if (wfd != -1 && wfd != rfd)
fcntl(wfd, F_SETFD, FD_CLOEXEC);
if (efd != -1 && efd != rfd && efd != wfd)
fcntl(efd, F_SETFD, FD_CLOEXEC);
c->rfd = rfd;
c->wfd = wfd;
c->sock = (rfd == wfd) ? rfd : -1;
c->efd = efd;
c->extended_usage = extusage;
if ((c->isatty = is_tty) != 0)
debug2("channel %d: rfd %d isatty", c->self, c->rfd);
#ifdef _AIX
/* XXX: Later AIX versions can't push as much data to tty */
c->wfd_isatty = is_tty || isatty(c->wfd);
#endif
/* 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 found;
u_int i;
Channel *c;
/* Do initial allocation if this is the first call. */
if (channels_alloc == 0) {
channels_alloc = 10;
channels = xcalloc(channels_alloc, sizeof(Channel *));
for (i = 0; i < channels_alloc; i++)
channels[i] = 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 = (int)i;
break;
}
if (found < 0) {
/* 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 = xreallocarray(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] = xcalloc(1, sizeof(Channel));
buffer_init(&c->input);
buffer_init(&c->output);
buffer_init(&c->extended);
c->path = NULL;
c->listening_addr = NULL;
c->listening_port = 0;
c->ostate = CHAN_OUTPUT_OPEN;
c->istate = CHAN_INPUT_OPEN;
c->flags = 0;
channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
c->notbefore = 0;
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->detach_close = 0;
c->open_confirm = NULL;
c->open_confirm_ctx = NULL;
c->input_filter = NULL;
c->output_filter = NULL;
c->filter_ctx = NULL;
c->filter_cleanup = NULL;
c->ctl_chan = -1;
c->mux_rcb = NULL;
c->mux_ctx = NULL;
c->mux_pause = 0;
c->delayed = 1; /* prevent call to channel_post handler */
TAILQ_INIT(&c->status_confirms);
debug("channel %d: new [%s]", found, remote_name);
return c;
}
static int
channel_find_maxfd(void)
{
u_int i;
int max = 0;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL) {
max = MAXIMUM(max, c->rfd);
max = MAXIMUM(max, c->wfd);
max = MAXIMUM(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)
{
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;
u_int i, n;
Channel *other;
struct channel_confirm *cc;
for (n = 0, i = 0; i < channels_alloc; i++) {
if ((other = channels[i]) != NULL) {
n++;
/* detach from mux client and prepare for closing */
if (c->type == SSH_CHANNEL_MUX_CLIENT &&
other->type == SSH_CHANNEL_MUX_PROXY &&
other->mux_ctx == c) {
other->mux_ctx = NULL;
other->type = SSH_CHANNEL_OPEN;
other->istate = CHAN_INPUT_CLOSED;
other->ostate = CHAN_OUTPUT_CLOSED;
}
}
}
debug("channel %d: free: %s, nchannels %u", c->self,
c->remote_name ? c->remote_name : "???", n);
/* XXX more MUX cleanup: remove remote forwardings */
if (c->type == SSH_CHANNEL_MUX_CLIENT) {
for (i = 0; i < (u_int)num_permitted_opens; i++) {
if (permitted_opens[i].downstream != c)
continue;
/* cancel on the server, since mux client is gone */
debug("channel %d: cleanup remote forward for %s:%u",
c->self,
permitted_opens[i].listen_host,
permitted_opens[i].listen_port);
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("cancel-tcpip-forward");
packet_put_char(0);
packet_put_cstring(channel_rfwd_bind_host(
permitted_opens[i].listen_host));
packet_put_int(permitted_opens[i].listen_port);
packet_send();
/* unregister */
permitted_opens[i].listen_port = 0;
permitted_opens[i].port_to_connect = 0;
free(permitted_opens[i].host_to_connect);
permitted_opens[i].host_to_connect = NULL;
free(permitted_opens[i].listen_host);
permitted_opens[i].listen_host = NULL;
permitted_opens[i].listen_path = NULL;
permitted_opens[i].downstream = NULL;
}
}
s = channel_open_message();
debug3("channel %d: status: %s", c->self, s);
free(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);
free(c->remote_name);
c->remote_name = NULL;
free(c->path);
c->path = NULL;
free(c->listening_addr);
c->listening_addr = NULL;
while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
if (cc->abandon_cb != NULL)
cc->abandon_cb(c, cc->ctx);
TAILQ_REMOVE(&c->status_confirms, cc, entry);
explicit_bzero(cc, sizeof(*cc));
free(cc);
}
if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
c->filter_cleanup(c->self, c->filter_ctx);
channels[c->self] = NULL;
free(c);
}
void
channel_free_all(void)
{
u_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)
{
u_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)
{
u_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:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_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 (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)
{
u_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_MUX_LISTENER:
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
continue;
case SSH_CHANNEL_LARVAL:
continue;
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_MUX_CLIENT:
case SSH_CHANNEL_MUX_PROXY:
return 1;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
fatal("cannot happen: OUT_DRAIN");
default:
fatal("%s: bad channel type %d", __func__, c->type);
/* NOTREACHED */
}
}
return 0;
}
/* Returns the id of an open channel suitable for keepaliving */
int
channel_find_open(void)
{
u_int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c == NULL || c->remote_id < 0)
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_MUX_LISTENER:
case SSH_CHANNEL_MUX_CLIENT:
case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
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:
fatal("cannot happen: OUT_DRAIN");
default:
fatal("%s: bad channel type %d", __func__, 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;
u_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:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_MUX_LISTENER:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
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:
case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_MUX_CLIENT:
snprintf(buf, sizeof buf,
" #%d %.300s (t%d r%d i%u/%d o%u/%d fd %d/%d cc %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, c->ctl_chan);
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((char *)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 confirm %d", id, service, wantconfirm);
packet_start(SSH2_MSG_CHANNEL_REQUEST);
packet_put_int(c->remote_id);
packet_put_cstring(service);
packet_put_char(wantconfirm);
}
void
channel_register_status_confirm(int id, channel_confirm_cb *cb,
channel_confirm_abandon_cb *abandon_cb, void *ctx)
{
struct channel_confirm *cc;
Channel *c;
if ((c = channel_lookup(id)) == NULL)
fatal("channel_register_expect: %d: bad id", id);
cc = xcalloc(1, sizeof(*cc));
cc->cb = cb;
cc->abandon_cb = abandon_cb;
cc->ctx = ctx;
TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
}
void
channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_register_open_confirm: %d: bad id", id);
return;
}
c->open_confirm = fn;
c->open_confirm_ctx = ctx;
}
void
channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
{
Channel *c = channel_by_id(id);
if (c == NULL) {
logit("channel_register_cleanup: %d: bad id", id);
return;
}
c->detach_user = fn;
c->detach_close = do_close;
}
void
channel_cancel_cleanup(int id)
{
Channel *c = channel_by_id(id);
if (c == NULL) {
logit("channel_cancel_cleanup: %d: bad id", id);
return;
}
c->detach_user = NULL;
c->detach_close = 0;
}
void
channel_register_filter(int id, channel_infilter_fn *ifn,
channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
{
Channel *c = channel_lookup(id);
if (c == NULL) {
logit("channel_register_filter: %d: bad id", id);
return;
}
c->input_filter = ifn;
c->output_filter = ofn;
c->filter_ctx = ctx;
c->filter_cleanup = cfn;
}
void
channel_set_fds(int id, int rfd, int wfd, int efd,
int extusage, int nonblock, int is_tty, 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, is_tty);
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];
/* ARGSUSED */
static void
channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
{
FD_SET(c->sock, readset);
}
/* ARGSUSED */
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(Channel *c, fd_set *readset, fd_set *writeset)
{
if (c->istate == CHAN_INPUT_OPEN &&
c->remote_window > 0 &&
buffer_len(&c->input) < c->remote_window &&
buffer_check_alloc(&c->input, CHAN_RBUF))
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 (c->efd != -1 && !(c->istate == CHAN_INPUT_CLOSED &&
c->ostate == CHAN_OUTPUT_CLOSED)) {
if (c->extended_usage == CHAN_EXTENDED_WRITE &&
buffer_len(&c->extended) > 0)
FD_SET(c->efd, writeset);
else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
(c->extended_usage == CHAN_EXTENDED_READ ||
c->extended_usage == CHAN_EXTENDED_IGNORE) &&
buffer_len(&c->extended) < c->remote_window)
FD_SET(c->efd, readset);
}
/* XXX: What about efd? races? */
}
/*
* 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;
/* Is this being called after the refusal deadline? */
if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
verbose("Rejected X11 connection after ForwardX11Timeout "
"expired");
return -1;
}
/* 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 ||
timingsafe_bcmp(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(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);
chan_write_failed(c);
debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
}
}
static void
channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
{
if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
buffer_check_alloc(&c->input, CHAN_RBUF))
FD_SET(c->rfd, readset);
if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
/* clear buffer immediately (discard any partial packet) */
buffer_clear(&c->input);
chan_ibuf_empty(c);
/* Start output drain. XXX just kill chan? */
chan_rcvd_oclose(c);
}
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)
chan_obuf_empty(c);
}
}
/* try to decode a socks4 header */
/* ARGSUSED */
static int
channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
{
char *p, *host;
u_int len, have, i, found, need;
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 = (char *)buffer_ptr(&c->input);
need = 1;
/* SOCKS4A uses an invalid IP address 0.0.0.x */
if (p[4] == 0 && p[5] == 0 && p[6] == 0 && p[7] != 0) {
debug2("channel %d: socks4a request", c->self);
/* ... and needs an extra string (the hostname) */
need = 2;
}
/* Check for terminating NUL on the string(s) */
for (found = 0, i = len; i < have; i++) {
if (p[i] == '\0') {
found++;
if (found == need)
break;
}
if (i > 1024) {
/* the peer is probably sending garbage */
debug("channel %d: decode socks4: too long",
c->self);
return -1;
}
}
if (found < need)
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 = (char *)buffer_ptr(&c->input);
if (memchr(p, '\0', have) == NULL)
fatal("channel %d: decode socks4: user not nul terminated",
c->self);
len = strlen(p);
debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
len++; /* trailing '\0' */
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);
free(c->path);
c->path = NULL;
if (need == 1) { /* SOCKS4: one string */
host = inet_ntoa(s4_req.dest_addr);
c->path = xstrdup(host);
} else { /* SOCKS4A: two strings */
have = buffer_len(&c->input);
p = (char *)buffer_ptr(&c->input);
len = strlen(p);
debug2("channel %d: decode socks4a: host %s/%d",
c->self, p, len);
len++; /* trailing '\0' */
if (len > have)
fatal("channel %d: decode socks4a: len %d > have %d",
c->self, len, have);
if (len > NI_MAXHOST) {
error("channel %d: hostname \"%.100s\" too long",
c->self, p);
return -1;
}
c->path = xstrdup(p);
buffer_consume(&c->input, len);
}
c->host_port = ntohs(s4_req.dest_port);
debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
c->self, c->path, c->host_port, s4_req.command);
if (s4_req.command != 1) {
debug("channel %d: cannot handle: %s cn %d",
c->self, need == 1 ? "SOCKS4" : "SOCKS4A", 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, &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
/* ARGSUSED */
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;
char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
u_char *p;
u_int have, need, i, 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(&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;
}
need = sizeof(s5_req) + addrlen + 2;
if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
need++;
if (have < need)
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, &dest_addr, addrlen);
buffer_get(&c->input, (char *)&dest_port, 2);
dest_addr[addrlen] = '\0';
free(c->path);
c->path = NULL;
if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
if (addrlen >= NI_MAXHOST) {
error("channel %d: dynamic request: socks5 hostname "
"\"%.100s\" too long", c->self, dest_addr);
return -1;
}
c->path = xstrdup(dest_addr);
} else {
if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
return -1;
c->path = xstrdup(ntop);
}
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;
dest_port = 0; /* ignored */
buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
buffer_append(&c->output, &dest_port, sizeof(dest_port));
return 1;
}
Channel *
channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
int in, int out)
{
Channel *c;
debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
port_to_connect);
c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
-1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, "stdio-forward", /*nonblock*/0);
c->path = xstrdup(host_to_connect);
c->host_port = port_to_connect;
c->listening_port = 0;
c->force_drain = 1;
channel_register_fds(c, in, out, -1, 0, 1, 0);
port_open_helper(c, "direct-tcpip");
return c;
}
/* dynamic port forwarding */
static void
channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
{
u_char *p;
u_int have;
int ret;
have = buffer_len(&c->input);
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. */
/* ARGSUSED */
static void
channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
{
Channel *nc;
struct sockaddr_storage addr;
int newsock, oerrno;
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, (struct sockaddr *)&addr, &addrlen);
if (c->single_connection) {
oerrno = errno;
debug2("single_connection: closing X11 listener.");
channel_close_fd(&c->sock);
chan_mark_dead(c);
errno = oerrno;
}
if (newsock < 0) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
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);
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();
free(remote_ipaddr);
}
}
static void
port_open_helper(Channel *c, char *rtype)
{
char buf[1024];
char *local_ipaddr = get_local_ipaddr(c->sock);
int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock);
char *remote_ipaddr = get_peer_ipaddr(c->sock);
int remote_port = get_peer_port(c->sock);
if (remote_port == -1) {
/* Fake addr/port to appease peers that validate it (Tectia) */
free(remote_ipaddr);
remote_ipaddr = xstrdup("127.0.0.1");
remote_port = 65535;
}
snprintf(buf, sizeof buf,
"%s: listening port %d for %.100s port %d, "
"connect from %.200s port %d to %.100s port %d",
rtype, c->listening_port, c->path, c->host_port,
remote_ipaddr, remote_port, local_ipaddr, local_port);
free(c->remote_name);
c->remote_name = xstrdup(buf);
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 (strcmp(rtype, "direct-tcpip") == 0) {
/* target host, port */
packet_put_cstring(c->path);
packet_put_int(c->host_port);
} else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
/* target path */
packet_put_cstring(c->path);
} else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
/* listen path */
packet_put_cstring(c->path);
} else {
/* listen address, port */
packet_put_cstring(c->path);
packet_put_int(local_port);
}
if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
/* reserved for future owner/mode info */
packet_put_cstring("");
} else {
/* originator host and port */
packet_put_cstring(remote_ipaddr);
packet_put_int((u_int)remote_port);
}
packet_send();
free(remote_ipaddr);
free(local_ipaddr);
}
static void
channel_set_reuseaddr(int fd)
{
int on = 1;
/*
* Set socket options.
* Allow local port reuse in TIME_WAIT.
*/
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
}
void
channel_set_x11_refuse_time(u_int refuse_time)
{
x11_refuse_time = refuse_time;
}
/*
* This socket is listening for connections to a forwarded TCP/IP port.
*/
/* ARGSUSED */
static void
channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
{
Channel *nc;
struct sockaddr_storage 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->type == SSH_CHANNEL_RUNIX_LISTENER) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "forwarded-streamlocal@openssh.com";
} else if (c->host_port == PORT_STREAMLOCAL) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "direct-streamlocal@openssh.com";
} 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, (struct sockaddr *)&addr, &addrlen);
if (newsock < 0) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
if (c->host_port != PORT_STREAMLOCAL)
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;
if (c->path != NULL)
nc->path = xstrdup(c->path);
if (nextstate != SSH_CHANNEL_DYNAMIC)
port_open_helper(nc, rtype);
}
}
/*
* This is the authentication agent socket listening for connections from
* clients.
*/
/* ARGSUSED */
static void
channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
{
Channel *nc;
int newsock;
struct sockaddr_storage addr;
socklen_t addrlen;
if (FD_ISSET(c->sock, readset)) {
addrlen = sizeof(addr);
newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
if (newsock < 0) {
error("accept from auth socket: %.100s",
strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
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);
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);
packet_send();
}
}
/* ARGSUSED */
static void
channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
{
int err = 0, sock;
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 to %s port %d",
c->self, c->connect_ctx.host, c->connect_ctx.port);
channel_connect_ctx_free(&c->connect_ctx);
c->type = SSH_CHANNEL_OPEN;
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 {
debug("channel %d: connection failed: %s",
c->self, strerror(err));
/* Try next address, if any */
if ((sock = connect_next(&c->connect_ctx)) > 0) {
close(c->sock);
c->sock = c->rfd = c->wfd = sock;
channel_max_fd = channel_find_maxfd();
return;
}
/* Exhausted all addresses */
error("connect_to %.100s port %d: failed.",
c->connect_ctx.host, c->connect_ctx.port);
channel_connect_ctx_free(&c->connect_ctx);
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("");
}
chan_mark_dead(c);
}
packet_send();
}
}
/* ARGSUSED */
static int
channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
{
char buf[CHAN_RBUF];
int len, force;
force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
errno = 0;
len = read(c->rfd, buf, sizeof(buf));
if (len < 0 && (errno == EINTR ||
((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
return 1;
#ifndef PTY_ZEROREAD
if (len <= 0) {
#else
if ((!c->isatty && len <= 0) ||
(c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
#endif
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 {
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 if (c->datagram) {
buffer_put_string(&c->input, buf, len);
} else {
buffer_append(&c->input, buf, len);
}
}
return 1;
}
/* ARGSUSED */
static int
channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
{
struct termios tio;
u_char *data = NULL, *buf;
u_int dlen, olen = 0;
int len;
/* Send buffered output data to the socket. */
if (c->wfd != -1 &&
FD_ISSET(c->wfd, writeset) &&
buffer_len(&c->output) > 0) {
olen = buffer_len(&c->output);
if (c->output_filter != NULL) {
if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
debug2("channel %d: filter stops", c->self);
if (c->type != SSH_CHANNEL_OPEN)
chan_mark_dead(c);
else
chan_write_failed(c);
return -1;
}
} else if (c->datagram) {
buf = data = buffer_get_string(&c->output, &dlen);
} else {
buf = data = buffer_ptr(&c->output);
dlen = buffer_len(&c->output);
}
if (c->datagram) {
/* ignore truncated writes, datagrams might get lost */
len = write(c->wfd, buf, dlen);
free(data);
if (len < 0 && (errno == EINTR || errno == EAGAIN ||
errno == EWOULDBLOCK))
return 1;
if (len <= 0) {
if (c->type != SSH_CHANNEL_OPEN)
chan_mark_dead(c);
else
chan_write_failed(c);
return -1;
}
goto out;
}
#ifdef _AIX
/* XXX: Later AIX versions can't push as much data to tty */
if (c->wfd_isatty)
dlen = MIN(dlen, 8*1024);
#endif
len = write(c->wfd, buf, dlen);
if (len < 0 &&
(errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
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 {
chan_write_failed(c);
}
return -1;
}
#ifndef BROKEN_TCGETATTR_ICANON
if (c->isatty && dlen >= 1 && buf[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 + buf)
*/
packet_send_ignore(4 + len);
packet_send();
}
}
#endif
buffer_consume(&c->output, len);
}
out:
if (olen > 0)
c->local_consumed += olen - buffer_len(&c->output);
return 1;
}
static int
channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
{
char buf[CHAN_RBUF];
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 ||
errno == EWOULDBLOCK))
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->efd != -1 &&
(c->extended_usage == CHAN_EXTENDED_READ ||
c->extended_usage == CHAN_EXTENDED_IGNORE) &&
(c->detach_close || 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 ||
errno == EWOULDBLOCK) && !c->detach_close)))
return 1;
if (len <= 0) {
debug2("channel %d: closing read-efd %d",
c->self, c->efd);
channel_close_fd(&c->efd);
} else {
if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
debug3("channel %d: discard efd",
c->self);
} 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_max - c->local_window >
c->local_maxpacket*3) ||
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)
{
channel_handle_rfd(c, readset, writeset);
channel_handle_wfd(c, readset, writeset);
channel_handle_efd(c, readset, writeset);
channel_check_window(c);
}
static u_int
read_mux(Channel *c, u_int need)
{
char buf[CHAN_RBUF];
int len;
u_int rlen;
if (buffer_len(&c->input) < need) {
rlen = need - buffer_len(&c->input);
len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return buffer_len(&c->input);
if (len <= 0) {
debug2("channel %d: ctl read<=0 rfd %d len %d",
c->self, c->rfd, len);
chan_read_failed(c);
return 0;
} else
buffer_append(&c->input, buf, len);
}
return buffer_len(&c->input);
}
static void
channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
{
u_int need;
ssize_t len;
if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
(c->istate == CHAN_INPUT_OPEN ||
c->istate == CHAN_INPUT_WAIT_DRAIN)) {
/*
* Don't not read past the precise end of packets to
* avoid disrupting fd passing.
*/
if (read_mux(c, 4) < 4) /* read header */
return;
need = get_u32(buffer_ptr(&c->input));
#define CHANNEL_MUX_MAX_PACKET (256 * 1024)
if (need > CHANNEL_MUX_MAX_PACKET) {
debug2("channel %d: packet too big %u > %u",
c->self, CHANNEL_MUX_MAX_PACKET, need);
chan_rcvd_oclose(c);
return;
}
if (read_mux(c, need + 4) < need + 4) /* read body */
return;
if (c->mux_rcb(c) != 0) {
debug("channel %d: mux_rcb failed", c->self);
chan_mark_dead(c);
return;
}
}
if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
buffer_len(&c->output) > 0) {
len = write(c->wfd, buffer_ptr(&c->output),
buffer_len(&c->output));
if (len < 0 && (errno == EINTR || errno == EAGAIN))
return;
if (len <= 0) {
chan_mark_dead(c);
return;
}
buffer_consume(&c->output, len);
}
}
static void
channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
{
Channel *nc;
struct sockaddr_storage addr;
socklen_t addrlen;
int newsock;
uid_t euid;
gid_t egid;
if (!FD_ISSET(c->sock, readset))
return;
debug("multiplexing control connection");
/*
* Accept connection on control socket
*/
memset(&addr, 0, sizeof(addr));
addrlen = sizeof(addr);
if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
&addrlen)) == -1) {
error("%s accept: %s", __func__, strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
if (getpeereid(newsock, &euid, &egid) < 0) {
error("%s getpeereid failed: %s", __func__,
strerror(errno));
close(newsock);
return;
}
if ((euid != 0) && (getuid() != euid)) {
error("multiplex uid mismatch: peer euid %u != uid %u",
(u_int)euid, (u_int)getuid());
close(newsock);
return;
}
nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
newsock, newsock, -1, c->local_window_max,
c->local_maxpacket, 0, "mux-control", 1);
nc->mux_rcb = c->mux_rcb;
debug3("%s: new mux channel %d fd %d", __func__,
nc->self, nc->sock);
/* establish state */
nc->mux_rcb(nc);
/* mux state transitions must not elicit protocol messages */
nc->flags |= CHAN_LOCAL;
}
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;
}
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_UNIX_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_RUNIX_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_pre[SSH_CHANNEL_MUX_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_MUX_CLIENT] = &channel_pre_mux_client;
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_UNIX_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_RUNIX_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;
channel_post[SSH_CHANNEL_MUX_LISTENER] = &channel_post_mux_listener;
channel_post[SSH_CHANNEL_MUX_CLIENT] = &channel_post_mux_client;
}
/* gc dead channels */
static void
channel_garbage_collect(Channel *c)
{
if (c == NULL)
return;
if (c->detach_user != NULL) {
if (!chan_is_dead(c, c->detach_close))
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,
time_t *unpause_secs)
{
static int did_init = 0;
u_int i, oalloc;
Channel *c;
time_t now;
if (!did_init) {
channel_handler_init();
did_init = 1;
}
now = monotime();
if (unpause_secs != NULL)
*unpause_secs = 0;
for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
c = channels[i];
if (c == NULL)
continue;
if (c->delayed) {
if (ftab == channel_pre)
c->delayed = 0;
else
continue;
}
if (ftab[c->type] != NULL) {
/*
* Run handlers that are not paused.
*/
if (c->notbefore <= now)
(*ftab[c->type])(c, readset, writeset);
else if (unpause_secs != NULL) {
/*
* Collect the time that the earliest
* channel comes off pause.
*/
debug3("%s: chan %d: skip for %d more seconds",
__func__, c->self,
(int)(c->notbefore - now));
if (*unpause_secs == 0 ||
(c->notbefore - now) < *unpause_secs)
*unpause_secs = c->notbefore - now;
}
}
channel_garbage_collect(c);
}
if (unpause_secs != NULL && *unpause_secs != 0)
debug3("%s: first channel unpauses in %d seconds",
__func__, (int)*unpause_secs);
}
/*
* 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,
u_int *nallocp, time_t *minwait_secs, int rekeying)
{
u_int n, sz, nfdset;
n = MAXIMUM(*maxfdp, channel_max_fd);
nfdset = howmany(n+1, NFDBITS);
/* Explicitly test here, because xrealloc isn't always called */
if (nfdset && SIZE_MAX / nfdset < sizeof(fd_mask))
fatal("channel_prepare_select: max_fd (%d) is too large", n);
sz = nfdset * sizeof(fd_mask);
/* perhaps check sz < nalloc/2 and shrink? */
if (*readsetp == NULL || sz > *nallocp) {
*readsetp = xreallocarray(*readsetp, nfdset, sizeof(fd_mask));
*writesetp = xreallocarray(*writesetp, nfdset, sizeof(fd_mask));
*nallocp = sz;
}
*maxfdp = n;
memset(*readsetp, 0, sz);
memset(*writesetp, 0, sz);
if (!rekeying)
channel_handler(channel_pre, *readsetp, *writesetp,
minwait_secs);
}
/*
* 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, NULL);
}
/* If there is data to send to the connection, enqueue some of it now. */
void
channel_output_poll(void)
{
Channel *c;
u_int i, 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 (c->type != SSH_CHANNEL_OPEN)
continue;
if ((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) {
if (c->datagram) {
if (len > 0) {
u_char *data;
u_int dlen;
data = buffer_get_string(&c->input,
&dlen);
if (dlen > c->remote_window ||
dlen > c->remote_maxpacket) {
debug("channel %d: datagram "
"too big for channel",
c->self);
free(data);
continue;
}
packet_start(SSH2_MSG_CHANNEL_DATA);
packet_put_int(c->remote_id);
packet_put_string(data, dlen);
packet_send();
c->remote_window -= dlen;
free(data);
}
continue;
}
/*
* Send some data for the other side over the secure
* connection.
*/
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
if (len > 0) {
packet_start(SSH2_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) {
/*
* 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 (!(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);
}
}
}
/* -- mux proxy support */
/*
* When multiplexing channel messages for mux clients we have to deal
* with downstream messages from the mux client and upstream messages
* from the ssh server:
* 1) Handling downstream messages is straightforward and happens
* in channel_proxy_downstream():
* - We forward all messages (mostly) unmodified to the server.
* - However, in order to route messages from upstream to the correct
* downstream client, we have to replace the channel IDs used by the
* mux clients with a unique channel ID because the mux clients might
* use conflicting channel IDs.
* - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and
* SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local
* SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID
* with the newly allocated channel ID.
* 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY
* channels and procesed by channel_proxy_upstream(). The local channel ID
* is then translated back to the original mux client ID.
* 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE
* messages so we can clean up SSH_CHANNEL_MUX_PROXY channels.
* 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the
* downstream mux client are removed.
* 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server
* requires more work, because they are not addressed to a specific
* channel. E.g. client_request_forwarded_tcpip() needs to figure
* out whether the request is addressed to the local client or a
* specific downstream client based on the listen-address/port.
* 6) Agent and X11-Forwarding have a similar problem and are currenly
* not supported as the matching session/channel cannot be identified
* easily.
*/
/*
* receive packets from downstream mux clients:
* channel callback fired on read from mux client, creates
* SSH_CHANNEL_MUX_PROXY channels and translates channel IDs
* on channel creation.
*/
int
channel_proxy_downstream(Channel *downstream)
{
Channel *c = NULL;
struct ssh *ssh = active_state;
struct sshbuf *original = NULL, *modified = NULL;
const u_char *cp;
char *ctype = NULL, *listen_host = NULL;
u_char type;
size_t have;
int ret = -1, r, idx;
u_int id, remote_id, listen_port;
/* sshbuf_dump(&downstream->input, stderr); */
if ((r = sshbuf_get_string_direct(&downstream->input, &cp, &have))
!= 0) {
error("%s: malformed message: %s", __func__, ssh_err(r));
return -1;
}
if (have < 2) {
error("%s: short message", __func__);
return -1;
}
type = cp[1];
/* skip padlen + type */
cp += 2;
have -= 2;
if (ssh_packet_log_type(type))
debug3("%s: channel %u: down->up: type %u", __func__,
downstream->self, type);
switch (type) {
case SSH2_MSG_CHANNEL_OPEN:
if ((original = sshbuf_from(cp, have)) == NULL ||
(modified = sshbuf_new()) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 ||
(r = sshbuf_get_u32(original, &id)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
-1, -1, -1, 0, 0, 0, ctype, 1);
c->mux_ctx = downstream; /* point to mux client */
c->mux_downstream_id = id; /* original downstream id */
if ((r = sshbuf_put_cstring(modified, ctype)) != 0 ||
(r = sshbuf_put_u32(modified, c->self)) != 0 ||
(r = sshbuf_putb(modified, original)) != 0) {
error("%s: compose error %s", __func__, ssh_err(r));
channel_free(c);
goto out;
}
break;
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
/*
* Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we
* need to parse 'remote_id' instead of 'ctype'.
*/
if ((original = sshbuf_from(cp, have)) == NULL ||
(modified = sshbuf_new()) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_u32(original, &remote_id)) != 0 ||
(r = sshbuf_get_u32(original, &id)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
-1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
c->mux_ctx = downstream; /* point to mux client */
c->mux_downstream_id = id;
c->remote_id = remote_id;
if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
(r = sshbuf_put_u32(modified, c->self)) != 0 ||
(r = sshbuf_putb(modified, original)) != 0) {
error("%s: compose error %s", __func__, ssh_err(r));
channel_free(c);
goto out;
}
break;
case SSH2_MSG_GLOBAL_REQUEST:
if ((original = sshbuf_from(cp, have)) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
if (strcmp(ctype, "tcpip-forward") != 0) {
error("%s: unsupported request %s", __func__, ctype);
goto out;
}
if ((r = sshbuf_get_u8(original, NULL)) != 0 ||
(r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 ||
(r = sshbuf_get_u32(original, &listen_port)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
if (listen_port > 65535) {
error("%s: tcpip-forward for %s: bad port %u",
__func__, listen_host, listen_port);
goto out;
}
/* Record that connection to this host/port is permitted. */
permitted_opens = xreallocarray(permitted_opens,
num_permitted_opens + 1, sizeof(*permitted_opens));
idx = num_permitted_opens++;
permitted_opens[idx].host_to_connect = xstrdup("<mux>");
permitted_opens[idx].port_to_connect = -1;
permitted_opens[idx].listen_host = listen_host;
permitted_opens[idx].listen_port = (int)listen_port;
permitted_opens[idx].downstream = downstream;
listen_host = NULL;
break;
case SSH2_MSG_CHANNEL_CLOSE:
if (have < 4)
break;
remote_id = PEEK_U32(cp);
if ((c = channel_by_remote_id(remote_id)) != NULL) {
if (c->flags & CHAN_CLOSE_RCVD)
channel_free(c);
else
c->flags |= CHAN_CLOSE_SENT;
}
break;
}
if (modified) {
if ((r = sshpkt_start(ssh, type)) != 0 ||
(r = sshpkt_putb(ssh, modified)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
error("%s: send %s", __func__, ssh_err(r));
goto out;
}
} else {
if ((r = sshpkt_start(ssh, type)) != 0 ||
(r = sshpkt_put(ssh, cp, have)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
error("%s: send %s", __func__, ssh_err(r));
goto out;
}
}
ret = 0;
out:
free(ctype);
free(listen_host);
sshbuf_free(original);
sshbuf_free(modified);
return ret;
}
/*
* receive packets from upstream server and de-multiplex packets
* to correct downstream:
* implemented as a helper for channel input handlers,
* replaces local (proxy) channel ID with downstream channel ID.
*/
int
channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
{
struct ssh *ssh = active_state;
struct sshbuf *b = NULL;
Channel *downstream;
const u_char *cp = NULL;
size_t len;
int r;
/*
* When receiving packets from the peer we need to check whether we
* need to forward the packets to the mux client. In this case we
* restore the orignal channel id and keep track of CLOSE messages,
* so we can cleanup the channel.
*/
if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY)
return 0;
if ((downstream = c->mux_ctx) == NULL)
return 0;
switch (type) {
case SSH2_MSG_CHANNEL_CLOSE:
case SSH2_MSG_CHANNEL_DATA:
case SSH2_MSG_CHANNEL_EOF:
case SSH2_MSG_CHANNEL_EXTENDED_DATA:
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
case SSH2_MSG_CHANNEL_OPEN_FAILURE:
case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
case SSH2_MSG_CHANNEL_SUCCESS:
case SSH2_MSG_CHANNEL_FAILURE:
case SSH2_MSG_CHANNEL_REQUEST:
break;
default:
debug2("%s: channel %u: unsupported type %u", __func__,
c->self, type);
return 0;
}
if ((b = sshbuf_new()) == NULL) {
error("%s: alloc reply", __func__);
goto out;
}
/* get remaining payload (after id) */
cp = sshpkt_ptr(ssh, &len);
if (cp == NULL) {
error("%s: no packet", __func__);
goto out;
}
/* translate id and send to muxclient */
if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
(r = sshbuf_put_u8(b, type)) != 0 ||
(r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
(r = sshbuf_put(b, cp, len)) != 0 ||
(r = sshbuf_put_stringb(&downstream->output, b)) != 0) {
error("%s: compose for muxclient %s", __func__, ssh_err(r));
goto out;
}
/* sshbuf_dump(b, stderr); */
if (ssh_packet_log_type(type))
debug3("%s: channel %u: up->down: type %u", __func__, c->self,
type);
out:
/* update state */
switch (type) {
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
/* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
if (cp && len > 4)
c->remote_id = PEEK_U32(cp);
break;
case SSH2_MSG_CHANNEL_CLOSE:
if (c->flags & CHAN_CLOSE_SENT)
channel_free(c);
else
c->flags |= CHAN_CLOSE_RCVD;
break;
}
sshbuf_free(b);
return 1;
}
/* -- protocol input */
/* ARGSUSED */
int
channel_input_data(int type, u_int32_t seq, void *ctxt)
{
int id;
const u_char *data;
u_int data_len, win_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);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
/* Ignore any data for non-open channels (might happen on close) */
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_X11_OPEN)
return 0;
/* Get the data. */
data = packet_get_string_ptr(&data_len);
win_len = data_len;
if (c->datagram)
win_len += 4; /* string length header */
/*
* Ignore data for protocol > 1.3 if output end is no longer open.
* For protocol 2 the sending side is reducing its window as it sends
* data, so we must 'fake' consumption of the data in order to ensure
* that window updates are sent back. Otherwise the connection might
* deadlock.
*/
if (c->ostate != CHAN_OUTPUT_OPEN) {
c->local_window -= win_len;
c->local_consumed += win_len;
return 0;
}
if (win_len > c->local_maxpacket) {
logit("channel %d: rcvd big packet %d, maxpack %d",
c->self, win_len, c->local_maxpacket);
}
if (win_len > c->local_window) {
logit("channel %d: rcvd too much data %d, win %d",
c->self, win_len, c->local_window);
return 0;
}
c->local_window -= win_len;
if (c->datagram)
buffer_put_string(&c->output, data, data_len);
else
buffer_append(&c->output, data, data_len);
packet_check_eom();
return 0;
}
/* ARGSUSED */
int
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 (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
if (c->type != SSH_CHANNEL_OPEN) {
logit("channel %d: ext data for non open", id);
return 0;
}
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 0;
}
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);
free(data);
return 0;
}
debug2("channel %d: rcvd ext data %d", c->self, data_len);
c->local_window -= data_len;
buffer_append(&c->extended, data, data_len);
free(data);
return 0;
}
/* ARGSUSED */
int
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);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
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);
}
return 0;
}
/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
/* ARGSUSED */
int
channel_input_oclose(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received oclose for nonexistent channel %d.", id);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
packet_check_eom();
chan_rcvd_oclose(c);
return 0;
}
/* ARGSUSED */
int
channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received close confirmation for "
"out-of-range channel %d.", id);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
packet_check_eom();
if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
packet_disconnect("Received close confirmation for "
"non-closed channel %d (type %d).", id, c->type);
channel_free(c);
return 0;
}
/* ARGSUSED */
int
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)
packet_disconnect("Received open confirmation for "
"unknown channel %d.", id);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
if (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;
c->remote_window = packet_get_int();
c->remote_maxpacket = packet_get_int();
if (c->open_confirm) {
debug2("callback start");
c->open_confirm(c->self, 1, c->open_confirm_ctx);
debug2("callback done");
}
debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
c->remote_window, c->remote_maxpacket);
packet_check_eom();
return 0;
}
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";
}
/* ARGSUSED */
int
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)
packet_disconnect("Received open failure for "
"unknown channel %d.", id);
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
if (c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open failure for "
"non-opening channel %d.", id);
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 : "");
free(msg);
free(lang);
if (c->open_confirm) {
debug2("callback start");
c->open_confirm(c->self, 0, c->open_confirm_ctx);
debug2("callback done");
}
packet_check_eom();
/* Schedule the channel for cleanup/deletion. */
chan_mark_dead(c);
return 0;
}
/* ARGSUSED */
int
channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
{
Channel *c;
int id;
u_int adjust, tmp;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL) {
logit("Received window adjust for non-open channel %d.", id);
return 0;
}
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
adjust = packet_get_int();
packet_check_eom();
debug2("channel %d: rcvd adjust %u", id, adjust);
if ((tmp = c->remote_window + adjust) < c->remote_window)
fatal("channel %d: adjust %u overflows remote window %u",
id, adjust, c->remote_window);
c->remote_window = tmp;
return 0;
}
/* ARGSUSED */
int
channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
{
Channel *c;
struct channel_confirm *cc;
int id;
/* Reset keepalive timeout */
packet_set_alive_timeouts(0);
id = packet_get_int();
debug2("channel_input_status_confirm: type %d id %d", type, id);
if ((c = channel_lookup(id)) == NULL) {
logit("channel_input_status_confirm: %d: unknown", id);
return 0;
}
if (channel_proxy_upstream(c, type, seq, ctxt))
return 0;
packet_check_eom();
if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
return 0;
cc->cb(type, c, cc->ctx);
TAILQ_REMOVE(&c->status_confirms, cc, entry);
explicit_bzero(cc, sizeof(*cc));
free(cc);
return 0;
}
/* -- tcp forwarding */
void
channel_set_af(int af)
{
IPv4or6 = af;
}
/*
* Determine whether or not a port forward listens to loopback, the
* specified address or wildcard. On the client, a specified bind
* address will always override gateway_ports. On the server, a
* gateway_ports of 1 (``yes'') will override the client's specification
* and force a wildcard bind, whereas a value of 2 (``clientspecified'')
* will bind to whatever address the client asked for.
*
* Special-case listen_addrs are:
*
* "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
* "" (empty string), "*" -> wildcard v4/v6
* "localhost" -> loopback v4/v6
* "127.0.0.1" / "::1" -> accepted even if gateway_ports isn't set
*/
static const char *
channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
int is_client, struct ForwardOptions *fwd_opts)
{
const char *addr = NULL;
int wildcard = 0;
if (listen_addr == NULL) {
/* No address specified: default to gateway_ports setting */
if (fwd_opts->gateway_ports)
wildcard = 1;
} else if (fwd_opts->gateway_ports || is_client) {
if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
*listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
(!is_client && fwd_opts->gateway_ports == 1)) {
wildcard = 1;
/*
* Notify client if they requested a specific listen
* address and it was overridden.
*/
if (*listen_addr != '\0' &&
strcmp(listen_addr, "0.0.0.0") != 0 &&
strcmp(listen_addr, "*") != 0) {
packet_send_debug("Forwarding listen address "
"\"%s\" overridden by server "
"GatewayPorts", listen_addr);
}
} else if (strcmp(listen_addr, "localhost") != 0 ||
strcmp(listen_addr, "127.0.0.1") == 0 ||
strcmp(listen_addr, "::1") == 0) {
/* Accept localhost address when GatewayPorts=yes */
addr = listen_addr;
}
} else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
strcmp(listen_addr, "::1") == 0) {
/*
* If a specific IPv4/IPv6 localhost address has been
* requested then accept it even if gateway_ports is in
* effect. This allows the client to prefer IPv4 or IPv6.
*/
addr = listen_addr;
}
if (wildcardp != NULL)
*wildcardp = wildcard;
return addr;
}
static int
channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
int *allocated_listen_port, struct ForwardOptions *fwd_opts)
{
Channel *c;
int sock, r, success = 0, wildcard = 0, is_client;
struct addrinfo hints, *ai, *aitop;
const char *host, *addr;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
in_port_t *lport_p;
is_client = (type == SSH_CHANNEL_PORT_LISTENER);
if (is_client && fwd->connect_path != NULL) {
host = fwd->connect_path;
} else {
host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
fwd->listen_host : fwd->connect_host;
if (host == NULL) {
error("No forward host name.");
return 0;
}
if (strlen(host) >= NI_MAXHOST) {
error("Forward host name too long.");
return 0;
}
}
/* Determine the bind address, cf. channel_fwd_bind_addr() comment */
addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard,
is_client, fwd_opts);
debug3("%s: type %d wildcard %d addr %s", __func__,
type, wildcard, (addr == NULL) ? "NULL" : addr);
/*
* 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 = wildcard ? AI_PASSIVE : 0;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", fwd->listen_port);
if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
if (addr == NULL) {
/* This really shouldn't happen */
packet_disconnect("getaddrinfo: fatal error: %s",
ssh_gai_strerror(r));
} else {
error("%s: getaddrinfo(%.64s): %s", __func__, addr,
ssh_gai_strerror(r));
}
return 0;
}
if (allocated_listen_port != NULL)
*allocated_listen_port = 0;
for (ai = aitop; ai; ai = ai->ai_next) {
switch (ai->ai_family) {
case AF_INET:
lport_p = &((struct sockaddr_in *)ai->ai_addr)->
sin_port;
break;
case AF_INET6:
lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
sin6_port;
break;
default:
continue;
}
/*
* If allocating a port for -R forwards, then use the
* same port for all address families.
*/
if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
allocated_listen_port != NULL && *allocated_listen_port > 0)
*lport_p = htons(*allocated_listen_port);
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("%s: getnameinfo failed", __func__);
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;
}
channel_set_reuseaddr(sock);
if (ai->ai_family == AF_INET6)
sock_set_v6only(sock);
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, SSH_LISTEN_BACKLOG) < 0) {
error("listen: %.100s", strerror(errno));
close(sock);
continue;
}
/*
* fwd->listen_port == 0 requests a dynamically allocated port -
* record what we got.
*/
if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
allocated_listen_port != NULL &&
*allocated_listen_port == 0) {
*allocated_listen_port = get_local_port(sock);
debug("Allocated listen port %d",
*allocated_listen_port);
}
/* 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);
c->path = xstrdup(host);
c->host_port = fwd->connect_port;
c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
if (fwd->listen_port == 0 && allocated_listen_port != NULL &&
!(datafellows & SSH_BUG_DYNAMIC_RPORT))
c->listening_port = *allocated_listen_port;
else
c->listening_port = fwd->listen_port;
success = 1;
}
if (success == 0)
error("%s: cannot listen to port: %d", __func__,
fwd->listen_port);
freeaddrinfo(aitop);
return success;
}
static int
channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
struct ForwardOptions *fwd_opts)
{
struct sockaddr_un sunaddr;
const char *path;
Channel *c;
int port, sock;
mode_t omask;
switch (type) {
case SSH_CHANNEL_UNIX_LISTENER:
if (fwd->connect_path != NULL) {
if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) {
error("Local connecting path too long: %s",
fwd->connect_path);
return 0;
}
path = fwd->connect_path;
port = PORT_STREAMLOCAL;
} else {
if (fwd->connect_host == NULL) {
error("No forward host name.");
return 0;
}
if (strlen(fwd->connect_host) >= NI_MAXHOST) {
error("Forward host name too long.");
return 0;
}
path = fwd->connect_host;
port = fwd->connect_port;
}
break;
case SSH_CHANNEL_RUNIX_LISTENER:
path = fwd->listen_path;
port = PORT_STREAMLOCAL;
break;
default:
error("%s: unexpected channel type %d", __func__, type);
return 0;
}
if (fwd->listen_path == NULL) {
error("No forward path name.");
return 0;
}
if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) {
error("Local listening path too long: %s", fwd->listen_path);
return 0;
}
debug3("%s: type %d path %s", __func__, type, fwd->listen_path);
/* Start a Unix domain listener. */
omask = umask(fwd_opts->streamlocal_bind_mask);
sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG,
fwd_opts->streamlocal_bind_unlink);
umask(omask);
if (sock < 0)
return 0;
debug("Local forwarding listening on path %s.", fwd->listen_path);
/* Allocate a channel number for the socket. */
c = channel_new("unix listener", type, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, "unix listener", 1);
c->path = xstrdup(path);
c->host_port = port;
c->listening_port = PORT_STREAMLOCAL;
c->listening_addr = xstrdup(fwd->listen_path);
return 1;
}
static int
channel_cancel_rport_listener_tcpip(const char *host, u_short port)
{
u_int i;
int found = 0;
for (i = 0; i < channels_alloc; i++) {
Channel *c = channels[i];
if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
continue;
if (strcmp(c->path, host) == 0 && c->listening_port == port) {
debug2("%s: close channel %d", __func__, i);
channel_free(c);
found = 1;
}
}
return (found);
}
static int
channel_cancel_rport_listener_streamlocal(const char *path)
{
u_int i;
int found = 0;
for (i = 0; i < channels_alloc; i++) {
Channel *c = channels[i];
if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
continue;
if (c->path == NULL)
continue;
if (strcmp(c->path, path) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(c);
found = 1;
}
}
return (found);
}
int
channel_cancel_rport_listener(struct Forward *fwd)
{
if (fwd->listen_path != NULL)
return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
else
return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
}
static int
channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
int cport, struct ForwardOptions *fwd_opts)
{
u_int i;
int found = 0;
const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
for (i = 0; i < channels_alloc; i++) {
Channel *c = channels[i];
if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
continue;
if (c->listening_port != lport)
continue;
if (cport == CHANNEL_CANCEL_PORT_STATIC) {
/* skip dynamic forwardings */
if (c->host_port == 0)
continue;
} else {
if (c->host_port != cport)
continue;
}
if ((c->listening_addr == NULL && addr != NULL) ||
(c->listening_addr != NULL && addr == NULL))
continue;
if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(c);
found = 1;
}
}
return (found);
}
static int
channel_cancel_lport_listener_streamlocal(const char *path)
{
u_int i;
int found = 0;
if (path == NULL) {
error("%s: no path specified.", __func__);
return 0;
}
for (i = 0; i < channels_alloc; i++) {
Channel *c = channels[i];
if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
continue;
if (c->listening_addr == NULL)
continue;
if (strcmp(c->listening_addr, path) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(c);
found = 1;
}
}
return (found);
}
int
channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
{
if (fwd->listen_path != NULL)
return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
else
return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
}
/* protocol local port fwd, used by ssh (and sshd in v1) */
int
channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
{
if (fwd->listen_path != NULL) {
return channel_setup_fwd_listener_streamlocal(
SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
} else {
return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
fwd, NULL, fwd_opts);
}
}
/* protocol v2 remote port fwd, used by sshd */
int
channel_setup_remote_fwd_listener(struct Forward *fwd,
int *allocated_listen_port, struct ForwardOptions *fwd_opts)
{
if (fwd->listen_path != NULL) {
return channel_setup_fwd_listener_streamlocal(
SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
} else {
return channel_setup_fwd_listener_tcpip(
SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
fwd_opts);
}
}
/*
* Translate the requested rfwd listen host to something usable for
* this server.
*/
static const char *
channel_rfwd_bind_host(const char *listen_host)
{
if (listen_host == NULL) {
if (datafellows & SSH_BUG_RFWD_ADDR)
return "127.0.0.1";
else
return "localhost";
} else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
if (datafellows & SSH_BUG_RFWD_ADDR)
return "0.0.0.0";
else
return "";
} else
return listen_host;
}
/*
* Initiate forwarding of connections to port "port" on remote host through
* the secure channel to host:port from local side.
* Returns handle (index) for updating the dynamic listen port with
* channel_update_permitted_opens().
*/
int
channel_request_remote_forwarding(struct Forward *fwd)
{
int success = 0, idx = -1;
/* Send the forward request to the remote side. */
packet_start(SSH2_MSG_GLOBAL_REQUEST);
if (fwd->listen_path != NULL) {
packet_put_cstring("streamlocal-forward@openssh.com");
packet_put_char(1); /* boolean: want reply */
packet_put_cstring(fwd->listen_path);
} else {
packet_put_cstring("tcpip-forward");
packet_put_char(1); /* boolean: want reply */
packet_put_cstring(channel_rfwd_bind_host(fwd->listen_host));
packet_put_int(fwd->listen_port);
}
packet_send();
packet_write_wait();
/* Assume that server accepts the request */
success = 1;
if (success) {
/* Record that connection to this host/port is permitted. */
permitted_opens = xreallocarray(permitted_opens,
num_permitted_opens + 1, sizeof(*permitted_opens));
idx = num_permitted_opens++;
if (fwd->connect_path != NULL) {
permitted_opens[idx].host_to_connect =
xstrdup(fwd->connect_path);
permitted_opens[idx].port_to_connect =
PORT_STREAMLOCAL;
} else {
permitted_opens[idx].host_to_connect =
xstrdup(fwd->connect_host);
permitted_opens[idx].port_to_connect =
fwd->connect_port;
}
if (fwd->listen_path != NULL) {
permitted_opens[idx].listen_host = NULL;
permitted_opens[idx].listen_path =
xstrdup(fwd->listen_path);
permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
} else {
permitted_opens[idx].listen_host =
fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
permitted_opens[idx].listen_path = NULL;
permitted_opens[idx].listen_port = fwd->listen_port;
}
permitted_opens[idx].downstream = NULL;
}
return (idx);
}
static int
open_match(ForwardPermission *allowed_open, const char *requestedhost,
int requestedport)
{
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
allowed_open->port_to_connect != requestedport)
return 0;
if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 &&
strcmp(allowed_open->host_to_connect, requestedhost) != 0)
return 0;
return 1;
}
/*
* Note that in the listen host/port case
* we don't support FWD_PERMIT_ANY_PORT and
* need to translate between the configured-host (listen_host)
* and what we've sent to the remote server (channel_rfwd_bind_host)
*/
static int
open_listen_match_tcpip(ForwardPermission *allowed_open,
const char *requestedhost, u_short requestedport, int translate)
{
const char *allowed_host;
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->listen_port != requestedport)
return 0;
if (!translate && allowed_open->listen_host == NULL &&
requestedhost == NULL)
return 1;
allowed_host = translate ?
channel_rfwd_bind_host(allowed_open->listen_host) :
allowed_open->listen_host;
if (allowed_host == NULL ||
strcmp(allowed_host, requestedhost) != 0)
return 0;
return 1;
}
static int
open_listen_match_streamlocal(ForwardPermission *allowed_open,
const char *requestedpath)
{
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->listen_port != PORT_STREAMLOCAL)
return 0;
if (allowed_open->listen_path == NULL ||
strcmp(allowed_open->listen_path, requestedpath) != 0)
return 0;
return 1;
}
/*
* Request cancellation of remote forwarding of connection host:port from
* local side.
*/
static int
channel_request_rforward_cancel_tcpip(const char *host, u_short port)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
break;
}
if (i >= num_permitted_opens) {
debug("%s: requested forward not found", __func__);
return -1;
}
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("cancel-tcpip-forward");
packet_put_char(0);
packet_put_cstring(channel_rfwd_bind_host(host));
packet_put_int(port);
packet_send();
permitted_opens[i].listen_port = 0;
permitted_opens[i].port_to_connect = 0;
free(permitted_opens[i].host_to_connect);
permitted_opens[i].host_to_connect = NULL;
free(permitted_opens[i].listen_host);
permitted_opens[i].listen_host = NULL;
permitted_opens[i].listen_path = NULL;
permitted_opens[i].downstream = NULL;
return 0;
}
/*
* Request cancellation of remote forwarding of Unix domain socket
* path from local side.
*/
static int
channel_request_rforward_cancel_streamlocal(const char *path)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
if (open_listen_match_streamlocal(&permitted_opens[i], path))
break;
}
if (i >= num_permitted_opens) {
debug("%s: requested forward not found", __func__);
return -1;
}
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("cancel-streamlocal-forward@openssh.com");
packet_put_char(0);
packet_put_cstring(path);
packet_send();
permitted_opens[i].listen_port = 0;
permitted_opens[i].port_to_connect = 0;
free(permitted_opens[i].host_to_connect);
permitted_opens[i].host_to_connect = NULL;
permitted_opens[i].listen_host = NULL;
free(permitted_opens[i].listen_path);
permitted_opens[i].listen_path = NULL;
permitted_opens[i].downstream = NULL;
return 0;
}
/*
* Request cancellation of remote forwarding of a connection from local side.
*/
int
channel_request_rforward_cancel(struct Forward *fwd)
{
if (fwd->listen_path != NULL) {
return (channel_request_rforward_cancel_streamlocal(
fwd->listen_path));
} else {
return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
}
}
/*
* 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)
{
debug("allow port forwarding to host %s port %d", host, port);
permitted_opens = xreallocarray(permitted_opens,
num_permitted_opens + 1, sizeof(*permitted_opens));
permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
permitted_opens[num_permitted_opens].port_to_connect = port;
permitted_opens[num_permitted_opens].listen_host = NULL;
permitted_opens[num_permitted_opens].listen_path = NULL;
permitted_opens[num_permitted_opens].listen_port = 0;
permitted_opens[num_permitted_opens].downstream = NULL;
num_permitted_opens++;
all_opens_permitted = 0;
}
/*
* Update the listen port for a dynamic remote forward, after
* the actual 'newport' has been allocated. If 'newport' < 0 is
* passed then they entry will be invalidated.
*/
void
channel_update_permitted_opens(int idx, int newport)
{
if (idx < 0 || idx >= num_permitted_opens) {
debug("channel_update_permitted_opens: index out of range:"
" %d num_permitted_opens %d", idx, num_permitted_opens);
return;
}
debug("%s allowed port %d for forwarding to host %s port %d",
newport > 0 ? "Updating" : "Removing",
newport,
permitted_opens[idx].host_to_connect,
permitted_opens[idx].port_to_connect);
if (newport >= 0) {
permitted_opens[idx].listen_port =
(datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
} else {
permitted_opens[idx].listen_port = 0;
permitted_opens[idx].port_to_connect = 0;
free(permitted_opens[idx].host_to_connect);
permitted_opens[idx].host_to_connect = NULL;
free(permitted_opens[idx].listen_host);
permitted_opens[idx].listen_host = NULL;
free(permitted_opens[idx].listen_path);
permitted_opens[idx].listen_path = NULL;
}
}
int
channel_add_adm_permitted_opens(char *host, int port)
{
debug("config allows port forwarding to host %s port %d", host, port);
permitted_adm_opens = xreallocarray(permitted_adm_opens,
num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
permitted_adm_opens[num_adm_permitted_opens].host_to_connect
= xstrdup(host);
permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
return ++num_adm_permitted_opens;
}
void
channel_disable_adm_local_opens(void)
{
channel_clear_adm_permitted_opens();
permitted_adm_opens = xcalloc(sizeof(*permitted_adm_opens), 1);
permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
num_adm_permitted_opens = 1;
}
void
channel_clear_permitted_opens(void)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
free(permitted_opens[i].host_to_connect);
free(permitted_opens[i].listen_host);
free(permitted_opens[i].listen_path);
}
free(permitted_opens);
permitted_opens = NULL;
num_permitted_opens = 0;
}
void
channel_clear_adm_permitted_opens(void)
{
int i;
for (i = 0; i < num_adm_permitted_opens; i++) {
free(permitted_adm_opens[i].host_to_connect);
free(permitted_adm_opens[i].listen_host);
free(permitted_adm_opens[i].listen_path);
}
free(permitted_adm_opens);
permitted_adm_opens = NULL;
num_adm_permitted_opens = 0;
}
void
channel_print_adm_permitted_opens(void)
{
int i;
printf("permitopen");
if (num_adm_permitted_opens == 0) {
printf(" any\n");
return;
}
for (i = 0; i < num_adm_permitted_opens; i++)
if (permitted_adm_opens[i].host_to_connect == NULL)
printf(" none");
else
printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
permitted_adm_opens[i].port_to_connect);
printf("\n");
}
/* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
int
permitopen_port(const char *p)
{
int port;
if (strcmp(p, "*") == 0)
return FWD_PERMIT_ANY_PORT;
if ((port = a2port(p)) > 0)
return port;
return -1;
}
/* Try to start non-blocking connect to next host in cctx list */
static int
connect_next(struct channel_connect *cctx)
{
int sock, saved_errno;
struct sockaddr_un *sunaddr;
char ntop[NI_MAXHOST], strport[MAXIMUM(NI_MAXSERV,sizeof(sunaddr->sun_path))];
for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
switch (cctx->ai->ai_family) {
case AF_UNIX:
/* unix:pathname instead of host:port */
sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr;
strlcpy(ntop, "unix", sizeof(ntop));
strlcpy(strport, sunaddr->sun_path, sizeof(strport));
break;
case AF_INET:
case AF_INET6:
if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("connect_next: getnameinfo failed");
continue;
}
break;
default:
continue;
}
if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
cctx->ai->ai_protocol)) == -1) {
if (cctx->ai->ai_next == NULL)
error("socket: %.100s", strerror(errno));
else
verbose("socket: %.100s", strerror(errno));
continue;
}
if (set_nonblock(sock) == -1)
fatal("%s: set_nonblock(%d)", __func__, sock);
if (connect(sock, cctx->ai->ai_addr,
cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
debug("connect_next: host %.100s ([%.100s]:%s): "
"%.100s", cctx->host, ntop, strport,
strerror(errno));
saved_errno = errno;
close(sock);
errno = saved_errno;
continue; /* fail -- try next */
}
if (cctx->ai->ai_family != AF_UNIX)
set_nodelay(sock);
debug("connect_next: host %.100s ([%.100s]:%s) "
"in progress, fd=%d", cctx->host, ntop, strport, sock);
cctx->ai = cctx->ai->ai_next;
return sock;
}
return -1;
}
static void
channel_connect_ctx_free(struct channel_connect *cctx)
{
free(cctx->host);
if (cctx->aitop) {
if (cctx->aitop->ai_family == AF_UNIX)
free(cctx->aitop);
else
freeaddrinfo(cctx->aitop);
}
memset(cctx, 0, sizeof(*cctx));
}
/*
* Return CONNECTING channel to remote host:port or local socket path,
* passing back the failure reason if appropriate.
*/
static Channel *
connect_to_reason(const char *name, int port, char *ctype, char *rname,
int *reason, const char **errmsg)
{
struct addrinfo hints;
int gaierr;
int sock = -1;
char strport[NI_MAXSERV];
struct channel_connect cctx;
Channel *c;
memset(&cctx, 0, sizeof(cctx));
if (port == PORT_STREAMLOCAL) {
struct sockaddr_un *sunaddr;
struct addrinfo *ai;
if (strlen(name) > sizeof(sunaddr->sun_path)) {
error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
return (NULL);
}
/*
* Fake up a struct addrinfo for AF_UNIX connections.
* channel_connect_ctx_free() must check ai_family
* and use free() not freeaddirinfo() for AF_UNIX.
*/
ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr));
memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr));
ai->ai_addr = (struct sockaddr *)(ai + 1);
ai->ai_addrlen = sizeof(*sunaddr);
ai->ai_family = AF_UNIX;
ai->ai_socktype = SOCK_STREAM;
ai->ai_protocol = PF_UNSPEC;
sunaddr = (struct sockaddr_un *)ai->ai_addr;
sunaddr->sun_family = AF_UNIX;
strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
cctx.aitop = ai;
} else {
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop))
!= 0) {
if (errmsg != NULL)
*errmsg = ssh_gai_strerror(gaierr);
if (reason != NULL)
*reason = SSH2_OPEN_CONNECT_FAILED;
error("connect_to %.100s: unknown host (%s)", name,
ssh_gai_strerror(gaierr));
return NULL;
}
}
cctx.host = xstrdup(name);
cctx.port = port;
cctx.ai = cctx.aitop;
if ((sock = connect_next(&cctx)) == -1) {
error("connect to %.100s port %d failed: %s",
name, port, strerror(errno));
channel_connect_ctx_free(&cctx);
return NULL;
}
c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
c->connect_ctx = cctx;
return c;
}
/* Return CONNECTING channel to remote host:port or local socket path */
static Channel *
connect_to(const char *name, int port, char *ctype, char *rname)
{
return connect_to_reason(name, port, ctype, rname, NULL, NULL);
}
/*
* returns either the newly connected channel or the downstream channel
* that needs to deal with this connection.
*/
Channel *
channel_connect_by_listen_address(const char *listen_host,
u_short listen_port, char *ctype, char *rname)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
listen_port, 1)) {
if (permitted_opens[i].downstream)
return permitted_opens[i].downstream;
return connect_to(
permitted_opens[i].host_to_connect,
permitted_opens[i].port_to_connect, ctype, rname);
}
}
error("WARNING: Server requests forwarding for unknown listen_port %d",
listen_port);
return NULL;
}
Channel *
channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
return connect_to(
permitted_opens[i].host_to_connect,
permitted_opens[i].port_to_connect, ctype, rname);
}
}
error("WARNING: Server requests forwarding for unknown path %.100s",
path);
return NULL;
}
/* Check if connecting to that port is permitted and connect. */
Channel *
channel_connect_to_port(const char *host, u_short port, char *ctype,
char *rname, int *reason, const char **errmsg)
{
int i, permit, permit_adm = 1;
permit = all_opens_permitted;
if (!permit) {
for (i = 0; i < num_permitted_opens; i++)
if (open_match(&permitted_opens[i], host, port)) {
permit = 1;
break;
}
}
if (num_adm_permitted_opens > 0) {
permit_adm = 0;
for (i = 0; i < num_adm_permitted_opens; i++)
if (open_match(&permitted_adm_opens[i], host, port)) {
permit_adm = 1;
break;
}
}
if (!permit || !permit_adm) {
logit("Received request to connect to host %.100s port %d, "
"but the request was denied.", host, port);
if (reason != NULL)
*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
return NULL;
}
return connect_to_reason(host, port, ctype, rname, reason, errmsg);
}
/* Check if connecting to that path is permitted and connect. */
Channel *
channel_connect_to_path(const char *path, char *ctype, char *rname)
{
int i, permit, permit_adm = 1;
permit = all_opens_permitted;
if (!permit) {
for (i = 0; i < num_permitted_opens; i++)
if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
permit = 1;
break;
}
}
if (num_adm_permitted_opens > 0) {
permit_adm = 0;
for (i = 0; i < num_adm_permitted_opens; i++)
if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
permit_adm = 1;
break;
}
}
if (!permit || !permit_adm) {
logit("Received request to connect to path %.100s, "
"but the request was denied.", path);
return NULL;
}
return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
}
void
channel_send_window_changes(void)
{
u_int i;
struct winsize ws;
for (i = 0; i < channels_alloc; i++) {
if (channels[i] == NULL || !channels[i]->client_tty ||
channels[i]->type != SSH_CHANNEL_OPEN)
continue;
if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
continue;
channel_request_start(i, "window-change", 0);
packet_put_int((u_int)ws.ws_col);
packet_put_int((u_int)ws.ws_row);
packet_put_int((u_int)ws.ws_xpixel);
packet_put_int((u_int)ws.ws_ypixel);
packet_send();
}
}
/* -- 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, int **chanids)
{
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];
if (chanids == NULL)
return -1;
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", ssh_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)
#ifdef EPFNOSUPPORT
&& (errno != EPFNOSUPPORT)
#endif
) {
error("socket: %.100s", strerror(errno));
freeaddrinfo(aitop);
return -1;
} else {
debug("x11_create_display_inet: Socket family %d not supported",
ai->ai_family);
continue;
}
}
if (ai->ai_family == AF_INET6)
sock_set_v6only(sock);
if (x11_use_localhost)
channel_set_reuseaddr(sock);
if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
debug2("bind port %d: %.100s", port, strerror(errno));
close(sock);
for (n = 0; n < num_socks; n++) {
close(socks[n]);
}
num_socks = 0;
break;
}
socks[num_socks++] = sock;
if (num_socks == NUM_SOCKS)
break;
}
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, SSH_LISTEN_BACKLOG) < 0) {
error("listen: %.100s", strerror(errno));
close(sock);
return -1;
}
}
/* Allocate a channel for each socket. */
*chanids = xcalloc(num_socks + 1, sizeof(**chanids));
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;
(*chanids)[n] = nc->self;
}
(*chanids)[n] = -1;
/* Return the display number for the DISPLAY environment variable. */
*display_numberp = display_number;
return (0);
}
static int
connect_local_xsocket_path(const char *pathname)
{
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;
strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
return sock;
close(sock);
error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
return -1;
}
static int
connect_local_xsocket(u_int dnr)
{
char buf[1024];
snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
return connect_local_xsocket_path(buf);
}
#ifdef __APPLE__
static int
is_path_to_xsocket(const char *display, char *path, size_t pathlen)
{
struct stat sbuf;
if (strlcpy(path, display, pathlen) >= pathlen) {
error("%s: display path too long", __func__);
return 0;
}
if (display[0] != '/')
return 0;
if (stat(path, &sbuf) == 0) {
return 1;
} else {
char *dot = strrchr(path, '.');
if (dot != NULL) {
*dot = '\0';
if (stat(path, &sbuf) == 0) {
return 1;
}
}
}
return 0;
}
#endif
int
x11_connect_display(void)
{
u_int display_number;
const char *display;
char buf[1024], *cp;
struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV];
int gaierr, sock = 0;
/* 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.
*/
#ifdef __APPLE__
/* Check if display is a path to a socket (as set by launchd). */
{
char path[PATH_MAX];
if (is_path_to_xsocket(display, path, sizeof(path))) {
debug("x11_connect_display: $DISPLAY is launchd");
/* Create a socket. */
sock = connect_local_xsocket_path(path);
if (sock < 0)
return -1;
/* OK, we now have a connection to the display. */
return sock;
}
}
#endif
/*
* 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, "%u", &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, "%u", &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, "%u", 6000 + display_number);
if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
error("%.100s: unknown host. (%s)", buf,
ssh_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 %u: %.100s", buf,
6000 + display_number, strerror(errno));
close(sock);
continue;
}
/* Success */
break;
}
freeaddrinfo(aitop);
if (!ai) {
error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
strerror(errno));
return -1;
}
set_nodelay(sock);
return sock;
}
/*
* 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 *disp,
const char *proto, const char *data, int want_reply)
{
u_int data_len = (u_int) strlen(data) / 2;
u_int i, value;
char *new_data;
int screen_number;
const char *cp;
if (x11_saved_display == NULL)
x11_saved_display = xstrdup(disp);
else if (strcmp(disp, x11_saved_display) != 0) {
error("x11_request_forwarding_with_spoofing: different "
"$DISPLAY already forwarded");
return;
}
cp = strchr(disp, ':');
if (cp)
cp = strchr(cp, '.');
if (cp)
screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
else
screen_number = 0;
if (x11_saved_proto == NULL) {
/* Save protocol name. */
x11_saved_proto = xstrdup(proto);
/* Extract real authentication data. */
x11_saved_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);
x11_saved_data[i] = value;
}
x11_saved_data_len = data_len;
/* Generate fake data of the same length. */
x11_fake_data = xmalloc(data_len);
arc4random_buf(x11_fake_data, data_len);
x11_fake_data_len = data_len;
}
/* Convert the fake data into hex. */
new_data = tohex(x11_fake_data, data_len);
/* Send the request packet. */
channel_request_start(client_session_id, "x11-req", want_reply);
packet_put_char(0); /* XXX bool single connection */
packet_put_cstring(proto);
packet_put_cstring(new_data);
packet_put_int(screen_number);
packet_send();
packet_write_wait();
free(new_data);
}
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