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openssh/channels.c
Damien Miller 37f1c08473 - markus@cvs.openbsd.org 2013/04/06 16:07:00 
[channels.c sshd.c]
     handle ECONNABORTED for accept(); ok deraadt some time ago...
2013-04-23 15:20:43 +10:00

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/* $OpenBSD: channels.c,v 1.320 2013/04/06 16:07:00 markus 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/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>
#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 "ssh1.h"
#include "ssh2.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).
*/
typedef struct {
char *host_to_connect; /* Connect to 'host'. */
u_short port_to_connect; /* Connect to 'port'. */
u_short listen_port; /* Remote side should listen port number. */
} ForwardPermission;
/* List of all permitted host/port pairs to connect 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
/*
* 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;
/*
* 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);
/* 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;
}
/*
* 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:
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 = MAX(channel_max_fd, rfd);
channel_max_fd = MAX(channel_max_fd, wfd);
channel_max_fd = MAX(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);
c->wfd_isatty = is_tty || isatty(c->wfd);
/* enable nonblocking mode */
if (nonblock) {
if (rfd != -1)
set_nonblock(rfd);
if (wfd != -1)
set_nonblock(wfd);
if (efd != -1)
set_nonblock(efd);
}
}
/*
* Allocate a new channel object and set its type and socket. This will cause
* remote_name to be freed.
*/
Channel *
channel_new(char *ctype, int type, int rfd, int wfd, int efd,
u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
{
int 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 = xrealloc(channels, channels_alloc + 10,
sizeof(Channel *));
channels_alloc += 10;
debug2("channel: expanding %d", channels_alloc);
for (i = found; i < channels_alloc; i++)
channels[i] = NULL;
}
/* Initialize and return new channel. */
c = channels[found] = 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 = MAX(max, c->rfd);
max = MAX(max, c->wfd);
max = MAX(max, c->efd);
}
}
return max;
}
int
channel_close_fd(int *fdp)
{
int ret = 0, fd = *fdp;
if (fd != -1) {
ret = close(fd);
*fdp = -1;
if (fd == channel_max_fd)
channel_max_fd = channel_find_maxfd();
}
return ret;
}
/* Close all channel fd/socket. */
static void
channel_close_fds(Channel *c)
{
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;
struct channel_confirm *cc;
for (n = 0, i = 0; i < channels_alloc; i++)
if (channels[i])
n++;
debug("channel %d: free: %s, nchannels %u", c->self,
c->remote_name ? c->remote_name : "???", n);
s = channel_open_message();
debug3("channel %d: status: %s", c->self, s);
xfree(s);
if (c->sock != -1)
shutdown(c->sock, SHUT_RDWR);
channel_close_fds(c);
buffer_free(&c->input);
buffer_free(&c->output);
buffer_free(&c->extended);
if (c->remote_name) {
xfree(c->remote_name);
c->remote_name = NULL;
}
if (c->path) {
xfree(c->path);
c->path = NULL;
}
if (c->listening_addr) {
xfree(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);
bzero(cc, sizeof(*cc));
xfree(cc);
}
if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
c->filter_cleanup(c->self, c->filter_ctx);
channels[c->self] = NULL;
xfree(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:
channel_close_fd(&c->sock);
channel_free(c);
break;
}
}
}
}
/*
* Returns true if no channel has too much buffered data, and false if one or
* more channel is overfull.
*/
int
channel_not_very_much_buffered_data(void)
{
u_int i;
Channel *c;
for (i = 0; i < channels_alloc; i++) {
c = channels[i];
if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
#if 0
if (!compat20 &&
buffer_len(&c->input) > packet_get_maxsize()) {
debug2("channel %d: big input buffer %d",
c->self, buffer_len(&c->input));
return 0;
}
#endif
if (buffer_len(&c->output) > packet_get_maxsize()) {
debug2("channel %d: big output buffer %u > %u",
c->self, buffer_len(&c->output),
packet_get_maxsize());
return 0;
}
}
}
return 1;
}
/* Returns true if any channel is still open. */
int
channel_still_open(void)
{
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:
continue;
case SSH_CHANNEL_LARVAL:
if (!compat20)
fatal("cannot happen: SSH_CHANNEL_LARVAL");
continue;
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_MUX_CLIENT:
return 1;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
if (!compat13)
fatal("cannot happen: OUT_DRAIN");
return 1;
default:
fatal("channel_still_open: bad channel type %d", c->type);
/* NOTREACHED */
}
}
return 0;
}
/* Returns the id of an open channel suitable for keepaliving */
int
channel_find_open(void)
{
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_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
continue;
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
return i;
case SSH_CHANNEL_INPUT_DRAINING:
case SSH_CHANNEL_OUTPUT_DRAINING:
if (!compat13)
fatal("cannot happen: OUT_DRAIN");
return i;
default:
fatal("channel_find_open: bad channel type %d", c->type);
/* NOTREACHED */
}
}
return -1;
}
/*
* Returns a message describing the currently open forwarded connections,
* suitable for sending to the client. The message contains crlf pairs for
* newlines.
*/
char *
channel_open_message(void)
{
Buffer buffer;
Channel *c;
char buf[1024], *cp;
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_MUX_CLIENT:
case SSH_CHANNEL_MUX_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:
snprintf(buf, sizeof buf,
" #%d %.300s (t%d r%d i%d/%d o%d/%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(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 = xmalloc(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_13(Channel *c, fd_set *readset, fd_set *writeset)
{
if (buffer_len(&c->input) < packet_get_maxsize())
FD_SET(c->sock, readset);
if (buffer_len(&c->output) > 0)
FD_SET(c->sock, writeset);
}
static void
channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
{
u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
if (c->istate == CHAN_INPUT_OPEN &&
limit > 0 &&
buffer_len(&c->input) < limit &&
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 (compat20 && 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? */
}
/* ARGSUSED */
static void
channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
{
if (buffer_len(&c->input) == 0) {
packet_start(SSH_MSG_CHANNEL_CLOSE);
packet_put_int(c->remote_id);
packet_send();
c->type = SSH_CHANNEL_CLOSED;
debug2("channel %d: closing after input drain.", c->self);
}
}
/* ARGSUSED */
static void
channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
{
if (buffer_len(&c->output) == 0)
chan_mark_dead(c);
else
FD_SET(c->sock, writeset);
}
/*
* This is a special state for X11 authentication spoofing. An opened X11
* connection (when authentication spoofing is being done) remains in this
* state until the first packet has been completely read. The authentication
* data in that packet is then substituted by the real data if it matches the
* fake data, and the channel is put into normal mode.
* XXX All this happens at the client side.
* Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
*/
static int
x11_open_helper(Buffer *b)
{
u_char *ucp;
u_int proto_len, data_len;
/* Check if the fixed size part of the packet is in buffer. */
if (buffer_len(b) < 12)
return 0;
/* Parse the lengths of variable-length fields. */
ucp = buffer_ptr(b);
if (ucp[0] == 0x42) { /* Byte order MSB first. */
proto_len = 256 * ucp[6] + ucp[7];
data_len = 256 * ucp[8] + ucp[9];
} else if (ucp[0] == 0x6c) { /* Byte order LSB first. */
proto_len = ucp[6] + 256 * ucp[7];
data_len = ucp[8] + 256 * ucp[9];
} else {
debug2("Initial X11 packet contains bad byte order byte: 0x%x",
ucp[0]);
return -1;
}
/* Check if the whole packet is in buffer. */
if (buffer_len(b) <
12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
return 0;
/* Check if authentication protocol matches. */
if (proto_len != strlen(x11_saved_proto) ||
memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
debug2("X11 connection uses different authentication protocol.");
return -1;
}
/* Check if authentication data matches our fake data. */
if (data_len != x11_fake_data_len ||
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_13(Channel *c, fd_set *readset, fd_set *writeset)
{
int ret = x11_open_helper(&c->output);
if (ret == 1) {
/* Start normal processing for the channel. */
c->type = SSH_CHANNEL_OPEN;
channel_pre_open_13(c, readset, writeset);
} else if (ret == -1) {
/*
* We have received an X11 connection that has bad
* authentication information.
*/
logit("X11 connection rejected because of wrong authentication.");
buffer_clear(&c->input);
buffer_clear(&c->output);
channel_close_fd(&c->sock);
c->sock = -1;
c->type = SSH_CHANNEL_CLOSED;
packet_start(SSH_MSG_CHANNEL_CLOSE);
packet_put_int(c->remote_id);
packet_send();
}
}
static void
channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
{
int ret = x11_open_helper(&c->output);
/* c->force_drain = 1; */
if (ret == 1) {
c->type = SSH_CHANNEL_OPEN;
channel_pre_open(c, readset, writeset);
} else if (ret == -1) {
logit("X11 connection rejected because of wrong authentication.");
debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
chan_read_failed(c);
buffer_clear(&c->input);
chan_ibuf_empty(c);
buffer_clear(&c->output);
/* for proto v1, the peer will send an IEOF */
if (compat20)
chan_write_failed(c);
else
c->type = SSH_CHANNEL_OPEN;
debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
}
}
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 = 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 = buffer_ptr(&c->input);
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);
if (c->path != NULL) {
xfree(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 = 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;
u_char *p, dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
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, (char *)&dest_addr, addrlen);
buffer_get(&c->input, (char *)&dest_port, 2);
dest_addr[addrlen] = '\0';
if (c->path != NULL) {
xfree(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;
((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
dest_port = 0; /* ignored */
buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
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 = time(NULL) + 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);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring("x11");
packet_put_int(nc->self);
packet_put_int(nc->local_window_max);
packet_put_int(nc->local_maxpacket);
/* originator ipaddr and port */
packet_put_cstring(remote_ipaddr);
if (datafellows & SSH_BUG_X11FWD) {
debug2("ssh2 x11 bug compat mode");
} else {
packet_put_int(remote_port);
}
packet_send();
} else {
packet_start(SSH_SMSG_X11_OPEN);
packet_put_int(nc->self);
if (packet_get_protocol_flags() &
SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
packet_put_cstring(buf);
packet_send();
}
xfree(remote_ipaddr);
}
}
static void
port_open_helper(Channel *c, char *rtype)
{
int direct;
char buf[1024];
char *remote_ipaddr = get_peer_ipaddr(c->sock);
int remote_port = get_peer_port(c->sock);
if (remote_port == -1) {
/* Fake addr/port to appease peers that validate it (Tectia) */
xfree(remote_ipaddr);
remote_ipaddr = xstrdup("127.0.0.1");
remote_port = 65535;
}
direct = (strcmp(rtype, "direct-tcpip") == 0);
snprintf(buf, sizeof buf,
"%s: listening port %d for %.100s port %d, "
"connect from %.200s port %d",
rtype, c->listening_port, c->path, c->host_port,
remote_ipaddr, remote_port);
xfree(c->remote_name);
c->remote_name = xstrdup(buf);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring(rtype);
packet_put_int(c->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
if (direct) {
/* target host, port */
packet_put_cstring(c->path);
packet_put_int(c->host_port);
} else {
/* listen address, port */
packet_put_cstring(c->path);
packet_put_int(c->listening_port);
}
/* originator host and port */
packet_put_cstring(remote_ipaddr);
packet_put_int((u_int)remote_port);
packet_send();
} else {
packet_start(SSH_MSG_PORT_OPEN);
packet_put_int(c->self);
packet_put_cstring(c->path);
packet_put_int(c->host_port);
if (packet_get_protocol_flags() &
SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
packet_put_cstring(c->remote_name);
packet_send();
}
xfree(remote_ipaddr);
}
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));
}
/*
* 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->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 = time(NULL) + 1;
return;
}
set_nodelay(newsock);
nc = channel_new(rtype, nextstate, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket, 0, rtype, 1);
nc->listening_port = c->listening_port;
nc->host_port = c->host_port;
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 = time(NULL) + 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);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN);
packet_put_cstring("auth-agent@openssh.com");
packet_put_int(nc->self);
packet_put_int(c->local_window_max);
packet_put_int(c->local_maxpacket);
} else {
packet_start(SSH_SMSG_AGENT_OPEN);
packet_put_int(nc->self);
}
packet_send();
}
}
/* 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;
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(c->remote_id);
packet_put_int(c->self);
packet_put_int(c->local_window);
packet_put_int(c->local_maxpacket);
} else {
packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(c->remote_id);
packet_put_int(c->self);
}
} else {
debug("channel %d: 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);
if (compat20) {
packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(c->remote_id);
packet_put_int(SSH2_OPEN_CONNECT_FAILED);
if (!(datafellows & SSH_BUG_OPENFAILURE)) {
packet_put_cstring(strerror(err));
packet_put_cstring("");
}
} else {
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(c->remote_id);
}
chan_mark_dead(c);
}
packet_send();
}
}
/* 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 if (compat13) {
buffer_clear(&c->output);
c->type = SSH_CHANNEL_INPUT_DRAINING;
debug2("channel %d: input draining.", c->self);
} else {
chan_read_failed(c);
}
return -1;
}
if (c->input_filter != NULL) {
if (c->input_filter(c, buf, len) == -1) {
debug2("channel %d: filter stops", c->self);
chan_read_failed(c);
}
} else 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);
xfree(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 (compat20 && 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 if (compat13) {
buffer_clear(&c->output);
debug2("channel %d: input draining.", c->self);
c->type = SSH_CHANNEL_INPUT_DRAINING;
} else {
chan_write_failed(c);
}
return -1;
}
#ifndef BROKEN_TCGETATTR_ICANON
if (compat20 && 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 (compat20 && 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);
if (!compat20)
return;
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, MIN(rlen, CHAN_RBUF));
if (len <= 0) {
if (errno != EINTR && errno != EAGAIN) {
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 (!compat20)
fatal("%s: entered with !compat20", __func__);
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 = time(NULL) + 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;
}
/* ARGSUSED */
static void
channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
{
int len;
/* Send buffered output data to the socket. */
if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
len = write(c->sock, buffer_ptr(&c->output),
buffer_len(&c->output));
if (len <= 0)
buffer_clear(&c->output);
else
buffer_consume(&c->output, len);
}
}
static void
channel_handler_init_20(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_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_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;
}
static void
channel_handler_init_13(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open_13;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open_13;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_INPUT_DRAINING] = &channel_pre_input_draining;
channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_pre_output_draining;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
channel_post[SSH_CHANNEL_OUTPUT_DRAINING] = &channel_post_output_drain_13;
channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
}
static void
channel_handler_init_15(void)
{
channel_pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
channel_pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
channel_pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
channel_pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
channel_pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
channel_post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
channel_post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
channel_post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
channel_post[SSH_CHANNEL_OPEN] = &channel_post_open;
channel_post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
channel_post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
}
static void
channel_handler_init(void)
{
int i;
for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
channel_pre[i] = NULL;
channel_post[i] = NULL;
}
if (compat20)
channel_handler_init_20();
else if (compat13)
channel_handler_init_13();
else
channel_handler_init_15();
}
/* gc dead channels */
static void
channel_garbage_collect(Channel *c)
{
if (c == NULL)
return;
if (c->detach_user != NULL) {
if (!chan_is_dead(c, 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 = time(NULL);
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 = MAX(*maxfdp, channel_max_fd);
nfdset = howmany(n+1, NFDBITS);
/* Explicitly test here, because xrealloc isn't always called */
if (nfdset && SIZE_T_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 = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
*writesetp = xrealloc(*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 (compat13) {
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_INPUT_DRAINING)
continue;
} else {
if (c->type != SSH_CHANNEL_OPEN)
continue;
}
if (compat20 &&
(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
/* XXX is this true? */
debug3("channel %d: will not send data after close", c->self);
continue;
}
/* Get the amount of buffered data for this channel. */
if ((c->istate == CHAN_INPUT_OPEN ||
c->istate == CHAN_INPUT_WAIT_DRAIN) &&
(len = buffer_len(&c->input)) > 0) {
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);
xfree(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 + 4;
xfree(data);
}
continue;
}
/*
* Send some data for the other side over the secure
* connection.
*/
if (compat20) {
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
} else {
if (packet_is_interactive()) {
if (len > 1024)
len = 512;
} else {
/* Keep the packets at reasonable size. */
if (len > packet_get_maxsize()/2)
len = packet_get_maxsize()/2;
}
}
if (len > 0) {
packet_start(compat20 ?
SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
packet_put_int(c->remote_id);
packet_put_string(buffer_ptr(&c->input), len);
packet_send();
buffer_consume(&c->input, len);
c->remote_window -= len;
}
} else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
if (compat13)
fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
/*
* input-buffer is empty and read-socket shutdown:
* tell peer, that we will not send more data: send IEOF.
* hack for extended data: delay EOF if EFD still in use.
*/
if (CHANNEL_EFD_INPUT_ACTIVE(c))
debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
c->self, c->efd, buffer_len(&c->extended));
else
chan_ibuf_empty(c);
}
/* Send extended data, i.e. stderr */
if (compat20 &&
!(c->flags & CHAN_EOF_SENT) &&
c->remote_window > 0 &&
(len = buffer_len(&c->extended)) > 0 &&
c->extended_usage == CHAN_EXTENDED_READ) {
debug2("channel %d: rwin %u elen %u euse %d",
c->self, c->remote_window, buffer_len(&c->extended),
c->extended_usage);
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
packet_put_int(c->remote_id);
packet_put_int(SSH2_EXTENDED_DATA_STDERR);
packet_put_string(buffer_ptr(&c->extended), len);
packet_send();
buffer_consume(&c->extended, len);
c->remote_window -= len;
debug2("channel %d: sent ext data %d", c->self, len);
}
}
}
/* -- protocol input */
/* ARGSUSED */
void
channel_input_data(int type, u_int32_t seq, void *ctxt)
{
int id;
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);
/* Ignore any data for non-open channels (might happen on close) */
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_X11_OPEN)
return;
/* 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 (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
if (compat20) {
c->local_window -= win_len;
c->local_consumed += win_len;
}
return;
}
if (compat20) {
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;
}
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();
}
/* ARGSUSED */
void
channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
{
int id;
char *data;
u_int data_len, tcode;
Channel *c;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received extended_data for bad channel %d.", id);
if (c->type != SSH_CHANNEL_OPEN) {
logit("channel %d: ext data for non open", id);
return;
}
if (c->flags & CHAN_EOF_RCVD) {
if (datafellows & SSH_BUG_EXTEOF)
debug("channel %d: accepting ext data after eof", id);
else
packet_disconnect("Received extended_data after EOF "
"on channel %d.", id);
}
tcode = packet_get_int();
if (c->efd == -1 ||
c->extended_usage != CHAN_EXTENDED_WRITE ||
tcode != SSH2_EXTENDED_DATA_STDERR) {
logit("channel %d: bad ext data", c->self);
return;
}
data = packet_get_string(&data_len);
packet_check_eom();
if (data_len > c->local_window) {
logit("channel %d: rcvd too much extended_data %d, win %d",
c->self, data_len, c->local_window);
xfree(data);
return;
}
debug2("channel %d: rcvd ext data %d", c->self, data_len);
c->local_window -= data_len;
buffer_append(&c->extended, data, data_len);
xfree(data);
}
/* ARGSUSED */
void
channel_input_ieof(int type, u_int32_t seq, void *ctxt)
{
int id;
Channel *c;
id = packet_get_int();
packet_check_eom();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received ieof for nonexistent channel %d.", id);
chan_rcvd_ieof(c);
/* XXX force input close */
if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
debug("channel %d: FORCE input drain", c->self);
c->istate = CHAN_INPUT_WAIT_DRAIN;
if (buffer_len(&c->input) == 0)
chan_ibuf_empty(c);
}
}
/* ARGSUSED */
void
channel_input_close(int type, u_int32_t seq, void *ctxt)
{
int id;
Channel *c;
id = packet_get_int();
packet_check_eom();
c = channel_lookup(id);
if (c == NULL)
packet_disconnect("Received close for nonexistent channel %d.", id);
/*
* Send a confirmation that we have closed the channel and no more
* data is coming for it.
*/
packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
packet_put_int(c->remote_id);
packet_send();
/*
* If the channel is in closed state, we have sent a close request,
* and the other side will eventually respond with a confirmation.
* Thus, we cannot free the channel here, because then there would be
* no-one to receive the confirmation. The channel gets freed when
* the confirmation arrives.
*/
if (c->type != SSH_CHANNEL_CLOSED) {
/*
* Not a closed channel - mark it as draining, which will
* cause it to be freed later.
*/
buffer_clear(&c->input);
c->type = SSH_CHANNEL_OUTPUT_DRAINING;
}
}
/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
/* ARGSUSED */
void
channel_input_oclose(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
packet_check_eom();
if (c == NULL)
packet_disconnect("Received oclose for nonexistent channel %d.", id);
chan_rcvd_oclose(c);
}
/* ARGSUSED */
void
channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
{
int id = packet_get_int();
Channel *c = channel_lookup(id);
packet_check_eom();
if (c == NULL)
packet_disconnect("Received close confirmation for "
"out-of-range channel %d.", id);
if (c->type != SSH_CHANNEL_CLOSED)
packet_disconnect("Received close confirmation for "
"non-closed channel %d (type %d).", id, c->type);
channel_free(c);
}
/* ARGSUSED */
void
channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
{
int id, remote_id;
Channel *c;
id = packet_get_int();
c = channel_lookup(id);
if (c==NULL || c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open confirmation for "
"non-opening channel %d.", id);
remote_id = packet_get_int();
/* Record the remote channel number and mark that the channel is now open. */
c->remote_id = remote_id;
c->type = SSH_CHANNEL_OPEN;
if (compat20) {
c->remote_window = packet_get_int();
c->remote_maxpacket = packet_get_int();
if (c->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();
}
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 */
void
channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
{
int id, reason;
char *msg = NULL, *lang = NULL;
Channel *c;
id = packet_get_int();
c = channel_lookup(id);
if (c==NULL || c->type != SSH_CHANNEL_OPENING)
packet_disconnect("Received open failure for "
"non-opening channel %d.", id);
if (compat20) {
reason = packet_get_int();
if (!(datafellows & SSH_BUG_OPENFAILURE)) {
msg = packet_get_string(NULL);
lang = packet_get_string(NULL);
}
logit("channel %d: open failed: %s%s%s", id,
reason2txt(reason), msg ? ": ": "", msg ? msg : "");
if (msg != NULL)
xfree(msg);
if (lang != NULL)
xfree(lang);
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);
}
/* ARGSUSED */
void
channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
{
Channel *c;
int id;
u_int adjust;
if (!compat20)
return;
/* Get the channel number and verify it. */
id = packet_get_int();
c = channel_lookup(id);
if (c == NULL) {
logit("Received window adjust for non-open channel %d.", id);
return;
}
adjust = packet_get_int();
packet_check_eom();
debug2("channel %d: rcvd adjust %u", id, adjust);
c->remote_window += adjust;
}
/* ARGSUSED */
void
channel_input_port_open(int type, u_int32_t seq, void *ctxt)
{
Channel *c = NULL;
u_short host_port;
char *host, *originator_string;
int remote_id;
remote_id = packet_get_int();
host = packet_get_string(NULL);
host_port = packet_get_int();
if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
originator_string = packet_get_string(NULL);
} else {
originator_string = xstrdup("unknown (remote did not supply name)");
}
packet_check_eom();
c = channel_connect_to(host, host_port,
"connected socket", originator_string);
xfree(originator_string);
xfree(host);
if (c == NULL) {
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(remote_id);
packet_send();
} else
c->remote_id = remote_id;
}
/* ARGSUSED */
void
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();
packet_check_eom();
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;
}
;
if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
return;
cc->cb(type, c, cc->ctx);
TAILQ_REMOVE(&c->status_confirms, cc, entry);
bzero(cc, sizeof(*cc));
xfree(cc);
}
/* -- 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
*/
static const char *
channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
int is_client, int gateway_ports)
{
const char *addr = NULL;
int wildcard = 0;
if (listen_addr == NULL) {
/* No address specified: default to gateway_ports setting */
if (gateway_ports)
wildcard = 1;
} else if (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 && gateway_ports == 1))
wildcard = 1;
else if (strcmp(listen_addr, "localhost") != 0)
addr = listen_addr;
}
if (wildcardp != NULL)
*wildcardp = wildcard;
return addr;
}
static int
channel_setup_fwd_listener(int type, const char *listen_addr,
u_short listen_port, int *allocated_listen_port,
const char *host_to_connect, u_short port_to_connect, int gateway_ports)
{
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;
host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
listen_addr : host_to_connect;
is_client = (type == SSH_CHANNEL_PORT_LISTENER);
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(listen_addr, &wildcard,
is_client, gateway_ports);
debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
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", 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("channel_setup_fwd_listener: "
"getaddrinfo(%.64s): %s", 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 && 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("channel_setup_fwd_listener: getnameinfo failed");
continue;
}
/* Create a port to listen for the host. */
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0) {
/* this is no error since kernel may not support ipv6 */
verbose("socket: %.100s", strerror(errno));
continue;
}
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;
}
/*
* listen_port == 0 requests a dynamically allocated port -
* record what we got.
*/
if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
allocated_listen_port != NULL &&
*allocated_listen_port == 0) {
*allocated_listen_port = get_sock_port(sock, 1);
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 = port_to_connect;
c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
if (listen_port == 0 && allocated_listen_port != NULL &&
!(datafellows & SSH_BUG_DYNAMIC_RPORT))
c->listening_port = *allocated_listen_port;
else
c->listening_port = listen_port;
success = 1;
}
if (success == 0)
error("channel_setup_fwd_listener: cannot listen to port: %d",
listen_port);
freeaddrinfo(aitop);
return success;
}
int
channel_cancel_rport_listener(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);
}
int
channel_cancel_lport_listener(const char *lhost, u_short lport,
int cport, int gateway_ports)
{
u_int i;
int found = 0;
const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, gateway_ports);
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);
}
/* protocol local port fwd, used by ssh (and sshd in v1) */
int
channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
const char *host_to_connect, u_short port_to_connect, int gateway_ports)
{
return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
listen_host, listen_port, NULL, host_to_connect, port_to_connect,
gateway_ports);
}
/* protocol v2 remote port fwd, used by sshd */
int
channel_setup_remote_fwd_listener(const char *listen_address,
u_short listen_port, int *allocated_listen_port, int gateway_ports)
{
return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
listen_address, listen_port, allocated_listen_port,
NULL, 0, gateway_ports);
}
/*
* 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(const char *listen_host, u_short listen_port,
const char *host_to_connect, u_short port_to_connect)
{
int type, success = 0, idx = -1;
/* Send the forward request to the remote side. */
if (compat20) {
packet_start(SSH2_MSG_GLOBAL_REQUEST);
packet_put_cstring("tcpip-forward");
packet_put_char(1); /* boolean: want reply */
packet_put_cstring(channel_rfwd_bind_host(listen_host));
packet_put_int(listen_port);
packet_send();
packet_write_wait();
/* Assume that server accepts the request */
success = 1;
} else {
packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
packet_put_int(listen_port);
packet_put_cstring(host_to_connect);
packet_put_int(port_to_connect);
packet_send();
packet_write_wait();
/* Wait for response from the remote side. */
type = packet_read();
switch (type) {
case SSH_SMSG_SUCCESS:
success = 1;
break;
case SSH_SMSG_FAILURE:
break;
default:
/* Unknown packet */
packet_disconnect("Protocol error for port forward request:"
"received packet type %d.", type);
}
}
if (success) {
/* Record that connection to this host/port is permitted. */
permitted_opens = xrealloc(permitted_opens,
num_permitted_opens + 1, sizeof(*permitted_opens));
idx = num_permitted_opens++;
permitted_opens[idx].host_to_connect = xstrdup(host_to_connect);
permitted_opens[idx].port_to_connect = port_to_connect;
permitted_opens[idx].listen_port = listen_port;
}
return (idx);
}
/*
* Request cancellation of remote forwarding of connection host:port from
* local side.
*/
int
channel_request_rforward_cancel(const char *host, u_short port)
{
int i;
if (!compat20)
return -1;
for (i = 0; i < num_permitted_opens; i++) {
if (permitted_opens[i].host_to_connect != NULL &&
permitted_opens[i].listen_port == port)
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;
xfree(permitted_opens[i].host_to_connect);
permitted_opens[i].host_to_connect = NULL;
return 0;
}
/*
* This is called after receiving CHANNEL_FORWARDING_REQUEST. This initates
* listening for the port, and sends back a success reply (or disconnect
* message if there was an error).
*/
int
channel_input_port_forward_request(int is_root, int gateway_ports)
{
u_short port, host_port;
int success = 0;
char *hostname;
/* Get arguments from the packet. */
port = packet_get_int();
hostname = packet_get_string(NULL);
host_port = packet_get_int();
#ifndef HAVE_CYGWIN
/*
* Check that an unprivileged user is not trying to forward a
* privileged port.
*/
if (port < IPPORT_RESERVED && !is_root)
packet_disconnect(
"Requested forwarding of port %d but user is not root.",
port);
if (host_port == 0)
packet_disconnect("Dynamic forwarding denied.");
#endif
/* Initiate forwarding */
success = channel_setup_local_fwd_listener(NULL, port, hostname,
host_port, gateway_ports);
/* Free the argument string. */
xfree(hostname);
return (success ? 0 : -1);
}
/*
* 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 = xrealloc(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;
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;
xfree(permitted_opens[idx].host_to_connect);
permitted_opens[idx].host_to_connect = 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 = xrealloc(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;
return ++num_adm_permitted_opens;
}
void
channel_disable_adm_local_opens(void)
{
channel_clear_adm_permitted_opens();
permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
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++)
if (permitted_opens[i].host_to_connect != NULL)
xfree(permitted_opens[i].host_to_connect);
if (num_permitted_opens > 0) {
xfree(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++)
if (permitted_adm_opens[i].host_to_connect != NULL)
xfree(permitted_adm_opens[i].host_to_connect);
if (num_adm_permitted_opens > 0) {
xfree(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;
}
static int
port_match(u_short allowedport, u_short requestedport)
{
if (allowedport == FWD_PERMIT_ANY_PORT ||
allowedport == requestedport)
return 1;
return 0;
}
/* Try to start non-blocking connect to next host in cctx list */
static int
connect_next(struct channel_connect *cctx)
{
int sock, saved_errno;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
if (cctx->ai->ai_family != AF_INET &&
cctx->ai->ai_family != AF_INET6)
continue;
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;
}
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 */
}
debug("connect_next: host %.100s ([%.100s]:%s) "
"in progress, fd=%d", cctx->host, ntop, strport, sock);
cctx->ai = cctx->ai->ai_next;
set_nodelay(sock);
return sock;
}
return -1;
}
static void
channel_connect_ctx_free(struct channel_connect *cctx)
{
xfree(cctx->host);
if (cctx->aitop)
freeaddrinfo(cctx->aitop);
bzero(cctx, sizeof(*cctx));
cctx->host = NULL;
cctx->ai = cctx->aitop = NULL;
}
/* Return CONNECTING channel to remote host, port */
static Channel *
connect_to(const char *host, u_short port, char *ctype, char *rname)
{
struct addrinfo hints;
int gaierr;
int sock = -1;
char strport[NI_MAXSERV];
struct channel_connect cctx;
Channel *c;
memset(&cctx, 0, sizeof(cctx));
memset(&hints, 0, sizeof(hints));
hints.ai_family = IPv4or6;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(host, strport, &hints, &cctx.aitop)) != 0) {
error("connect_to %.100s: unknown host (%s)", host,
ssh_gai_strerror(gaierr));
return NULL;
}
cctx.host = xstrdup(host);
cctx.port = port;
cctx.ai = cctx.aitop;
if ((sock = connect_next(&cctx)) == -1) {
error("connect to %.100s port %d failed: %s",
host, 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;
}
Channel *
channel_connect_by_listen_address(u_short listen_port, char *ctype, char *rname)
{
int i;
for (i = 0; i < num_permitted_opens; i++) {
if (permitted_opens[i].host_to_connect != NULL &&
port_match(permitted_opens[i].listen_port, listen_port)) {
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;
}
/* Check if connecting to that port is permitted and connect. */
Channel *
channel_connect_to(const char *host, u_short port, 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 (permitted_opens[i].host_to_connect != NULL &&
port_match(permitted_opens[i].port_to_connect, port) &&
strcmp(permitted_opens[i].host_to_connect, host) == 0)
permit = 1;
}
if (num_adm_permitted_opens > 0) {
permit_adm = 0;
for (i = 0; i < num_adm_permitted_opens; i++)
if (permitted_adm_opens[i].host_to_connect != NULL &&
port_match(permitted_adm_opens[i].port_to_connect, port) &&
strcmp(permitted_adm_opens[i].host_to_connect, host)
== 0)
permit_adm = 1;
}
if (!permit || !permit_adm) {
logit("Received request to connect to host %.100s port %d, "
"but the request was denied.", host, port);
return NULL;
}
return connect_to(host, port, 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);
}
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.
*/
/* Check if the display is from launchd. */
#ifdef __APPLE__
if (strncmp(display, "/tmp/launch", 11) == 0) {
sock = connect_local_xsocket_path(display);
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;
}
/*
* This is called when SSH_SMSG_X11_OPEN is received. The packet contains
* the remote channel number. We should do whatever we want, and respond
* with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
*/
/* ARGSUSED */
void
x11_input_open(int type, u_int32_t seq, void *ctxt)
{
Channel *c = NULL;
int remote_id, sock = 0;
char *remote_host;
debug("Received X11 open request.");
remote_id = packet_get_int();
if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
remote_host = packet_get_string(NULL);
} else {
remote_host = xstrdup("unknown (remote did not supply name)");
}
packet_check_eom();
/* Obtain a connection to the real X display. */
sock = x11_connect_display();
if (sock != -1) {
/* Allocate a channel for this connection. */
c = channel_new("connected x11 socket",
SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
remote_host, 1);
c->remote_id = remote_id;
c->force_drain = 1;
}
xfree(remote_host);
if (c == NULL) {
/* Send refusal to the remote host. */
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(remote_id);
} else {
/* Send a confirmation to the remote host. */
packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
packet_put_int(remote_id);
packet_put_int(c->self);
}
packet_send();
}
/* dummy protocol handler that denies SSH-1 requests (agent/x11) */
/* ARGSUSED */
void
deny_input_open(int type, u_int32_t seq, void *ctxt)
{
int rchan = packet_get_int();
switch (type) {
case SSH_SMSG_AGENT_OPEN:
error("Warning: ssh server tried agent forwarding.");
break;
case SSH_SMSG_X11_OPEN:
error("Warning: ssh server tried X11 forwarding.");
break;
default:
error("deny_input_open: type %d", type);
break;
}
error("Warning: this is probably a break-in attempt by a malicious server.");
packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
packet_put_int(rchan);
packet_send();
}
/*
* Requests forwarding of X11 connections, generates fake authentication
* data, and enables authentication spoofing.
* This should be called in the client only.
*/
void
x11_request_forwarding_with_spoofing(int client_session_id, const char *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;
u_int32_t rnd = 0;
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 and generate fake data
* of the same length.
*/
x11_saved_data = xmalloc(data_len);
x11_fake_data = xmalloc(data_len);
for (i = 0; i < data_len; i++) {
if (sscanf(data + 2 * i, "%2x", &value) != 1)
fatal("x11_request_forwarding: bad "
"authentication data: %.100s", data);
if (i % 4 == 0)
rnd = arc4random();
x11_saved_data[i] = value;
x11_fake_data[i] = rnd & 0xff;
rnd >>= 8;
}
x11_saved_data_len = 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. */
if (compat20) {
channel_request_start(client_session_id, "x11-req", want_reply);
packet_put_char(0); /* XXX bool single connection */
} else {
packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
}
packet_put_cstring(proto);
packet_put_cstring(new_data);
packet_put_int(screen_number);
packet_send();
packet_write_wait();
xfree(new_data);
}
/* -- agent forwarding */
/* Sends a message to the server to request authentication fd forwarding. */
void
auth_request_forwarding(void)
{
packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
packet_send();
packet_write_wait();
}
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