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openssh/channels.c
dtucker@openbsd.org 4d2c87b4d1 upstream: We've standardized on memset over bzero, replace a couple 
that had slipped in.  ok deraadt markus djm.

OpenBSD-Commit-ID: f5be055554ee93e6cc66b0053b590bef3728dbd6
2020-05-01 13:13:28 +10:00

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/* $OpenBSD: channels.c,v 1.398 2020/04/25 06:59:36 dtucker Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* This file contains functions for generic socket connection forwarding.
* There is also code for initiating connection forwarding for X11 connections,
* arbitrary tcp/ip connections, and the authentication agent connection.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* SSH2 support added by Markus Friedl.
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
* Copyright (c) 1999 Dug Song. All rights reserved.
* Copyright (c) 1999 Theo de Raadt. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/un.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <netdb.h>
#include <stdarg.h>
#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include "openbsd-compat/sys-queue.h"
#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "ssherr.h"
#include "sshbuf.h"
#include "packet.h"
#include "log.h"
#include "misc.h"
#include "channels.h"
#include "compat.h"
#include "canohost.h"
#include "sshkey.h"
#include "authfd.h"
#include "pathnames.h"
#include "match.h"
/* -- agent forwarding */
#define NUM_SOCKS 10
/* -- tcp forwarding */
/* special-case port number meaning allow any port */
#define FWD_PERMIT_ANY_PORT 0
/* special-case wildcard meaning allow any host */
#define FWD_PERMIT_ANY_HOST "*"
/* -- X11 forwarding */
/* Maximum number of fake X11 displays to try. */
#define MAX_DISPLAYS 1000
/* Per-channel callback for pre/post select() actions */
typedef void chan_fn(struct ssh *, Channel *c,
fd_set *readset, fd_set *writeset);
/*
* Data structure for storing which hosts are permitted for forward requests.
* The local sides of any remote forwards are stored in this array to prevent
* a corrupt remote server from accessing arbitrary TCP/IP ports on our local
* network (which might be behind a firewall).
*/
/* XXX: streamlocal wants a path instead of host:port */
/* Overload host_to_connect; we could just make this match Forward */
/* XXX - can we use listen_host instead of listen_path? */
struct permission {
char *host_to_connect; /* Connect to 'host'. */
int port_to_connect; /* Connect to 'port'. */
char *listen_host; /* Remote side should listen address. */
char *listen_path; /* Remote side should listen path. */
int listen_port; /* Remote side should listen port. */
Channel *downstream; /* Downstream mux*/
};
/*
* Stores the forwarding permission state for a single direction (local or
* remote).
*/
struct permission_set {
/*
* List of all local permitted host/port pairs to allow for the
* user.
*/
u_int num_permitted_user;
struct permission *permitted_user;
/*
* List of all permitted host/port pairs to allow for the admin.
*/
u_int num_permitted_admin;
struct permission *permitted_admin;
/*
* If this is true, all opens/listens 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.
*/
int all_permitted;
};
/* Master structure for channels state */
struct ssh_channels {
/*
* Pointer to an array containing all allocated channels. The array
* is dynamically extended as needed.
*/
Channel **channels;
/*
* Size of the channel array. All slots of the array must always be
* initialized (at least the type field); unused slots set to NULL
*/
u_int channels_alloc;
/*
* Maximum file descriptor value used in any of the channels. This is
* updated in channel_new.
*/
int channel_max_fd;
/*
* '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.
*/
chan_fn **channel_pre;
chan_fn **channel_post;
/* -- tcp forwarding */
struct permission_set local_perms;
struct permission_set remote_perms;
/* -- X11 forwarding */
/* Saved X11 local (client) display. */
char *x11_saved_display;
/* Saved X11 authentication protocol name. */
char *x11_saved_proto;
/* Saved X11 authentication data. This is the real data. */
char *x11_saved_data;
u_int x11_saved_data_len;
/* Deadline after which all X11 connections are refused */
u_int x11_refuse_time;
/*
* Fake X11 authentication data. This is what the server will be
* sending us; we should replace any occurrences of this by the
* real data.
*/
u_char *x11_fake_data;
u_int x11_fake_data_len;
/* AF_UNSPEC or AF_INET or AF_INET6 */
int IPv4or6;
};
/* helper */
static void port_open_helper(struct ssh *ssh, Channel *c, char *rtype);
static const char *channel_rfwd_bind_host(const char *listen_host);
/* non-blocking connect helpers */
static int connect_next(struct channel_connect *);
static void channel_connect_ctx_free(struct channel_connect *);
static Channel *rdynamic_connect_prepare(struct ssh *, char *, char *);
static int rdynamic_connect_finish(struct ssh *, Channel *);
/* Setup helper */
static void channel_handler_init(struct ssh_channels *sc);
/* -- channel core */
void
channel_init_channels(struct ssh *ssh)
{
struct ssh_channels *sc;
if ((sc = calloc(1, sizeof(*sc))) == NULL)
fatal("%s: allocation failed", __func__);
sc->channels_alloc = 10;
sc->channels = xcalloc(sc->channels_alloc, sizeof(*sc->channels));
sc->IPv4or6 = AF_UNSPEC;
channel_handler_init(sc);
ssh->chanctxt = sc;
}
Channel *
channel_by_id(struct ssh *ssh, int id)
{
Channel *c;
if (id < 0 || (u_int)id >= ssh->chanctxt->channels_alloc) {
logit("%s: %d: bad id", __func__, id);
return NULL;
}
c = ssh->chanctxt->channels[id];
if (c == NULL) {
logit("%s: %d: bad id: channel free", __func__, id);
return NULL;
}
return c;
}
Channel *
channel_by_remote_id(struct ssh *ssh, u_int remote_id)
{
Channel *c;
u_int i;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c != NULL && c->have_remote_id && c->remote_id == remote_id)
return c;
}
return NULL;
}
/*
* Returns the channel if it is allowed to receive protocol messages.
* Private channels, like listening sockets, may not receive messages.
*/
Channel *
channel_lookup(struct ssh *ssh, int id)
{
Channel *c;
if ((c = channel_by_id(ssh, 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_RDYNAMIC_OPEN:
case SSH_CHANNEL_RDYNAMIC_FINISH:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_MUX_PROXY:
return c;
}
logit("Non-public channel %d, type %d.", id, c->type);
return NULL;
}
/*
* Register filedescriptors for a channel, used when allocating a channel or
* when the channel consumer/producer is ready, e.g. shell exec'd
*/
static void
channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
int extusage, int nonblock, int is_tty)
{
struct ssh_channels *sc = ssh->chanctxt;
/* Update the maximum file descriptor value. */
sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, rfd);
sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, wfd);
sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, efd);
if (rfd != -1)
fcntl(rfd, F_SETFD, FD_CLOEXEC);
if (wfd != -1 && wfd != rfd)
fcntl(wfd, F_SETFD, FD_CLOEXEC);
if (efd != -1 && efd != rfd && efd != wfd)
fcntl(efd, F_SETFD, FD_CLOEXEC);
c->rfd = rfd;
c->wfd = wfd;
c->sock = (rfd == wfd) ? rfd : -1;
c->efd = efd;
c->extended_usage = extusage;
if ((c->isatty = is_tty) != 0)
debug2("channel %d: rfd %d isatty", c->self, c->rfd);
#ifdef _AIX
/* XXX: Later AIX versions can't push as much data to tty */
c->wfd_isatty = is_tty || isatty(c->wfd);
#endif
/* enable nonblocking mode */
if (nonblock) {
if (rfd != -1)
set_nonblock(rfd);
if (wfd != -1)
set_nonblock(wfd);
if (efd != -1)
set_nonblock(efd);
}
}
/*
* Allocate a new channel object and set its type and socket. This will cause
* remote_name to be freed.
*/
Channel *
channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd,
u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
{
struct ssh_channels *sc = ssh->chanctxt;
u_int i, found;
Channel *c;
/* Try to find a free slot where to put the new channel. */
for (i = 0; i < sc->channels_alloc; i++) {
if (sc->channels[i] == NULL) {
/* Found a free slot. */
found = i;
break;
}
}
if (i >= sc->channels_alloc) {
/*
* There are no free slots. Take last+1 slot and expand
* the array.
*/
found = sc->channels_alloc;
if (sc->channels_alloc > CHANNELS_MAX_CHANNELS)
fatal("%s: internal error: channels_alloc %d too big",
__func__, sc->channels_alloc);
sc->channels = xrecallocarray(sc->channels, sc->channels_alloc,
sc->channels_alloc + 10, sizeof(*sc->channels));
sc->channels_alloc += 10;
debug2("channel: expanding %d", sc->channels_alloc);
}
/* Initialize and return new channel. */
c = sc->channels[found] = xcalloc(1, sizeof(Channel));
if ((c->input = sshbuf_new()) == NULL ||
(c->output = sshbuf_new()) == NULL ||
(c->extended = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new failed", __func__);
c->ostate = CHAN_OUTPUT_OPEN;
c->istate = CHAN_INPUT_OPEN;
channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, 0);
c->self = found;
c->type = type;
c->ctype = ctype;
c->local_window = window;
c->local_window_max = window;
c->local_maxpacket = maxpack;
c->remote_name = xstrdup(remote_name);
c->ctl_chan = -1;
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 void
channel_find_maxfd(struct ssh_channels *sc)
{
u_int i;
int max = 0;
Channel *c;
for (i = 0; i < sc->channels_alloc; i++) {
c = sc->channels[i];
if (c != NULL) {
max = MAXIMUM(max, c->rfd);
max = MAXIMUM(max, c->wfd);
max = MAXIMUM(max, c->efd);
}
}
sc->channel_max_fd = max;
}
int
channel_close_fd(struct ssh *ssh, int *fdp)
{
struct ssh_channels *sc = ssh->chanctxt;
int ret = 0, fd = *fdp;
if (fd != -1) {
ret = close(fd);
*fdp = -1;
if (fd == sc->channel_max_fd)
channel_find_maxfd(sc);
}
return ret;
}
/* Close all channel fd/socket. */
static void
channel_close_fds(struct ssh *ssh, Channel *c)
{
int sock = c->sock, rfd = c->rfd, wfd = c->wfd, efd = c->efd;
channel_close_fd(ssh, &c->sock);
if (rfd != sock)
channel_close_fd(ssh, &c->rfd);
if (wfd != sock && wfd != rfd)
channel_close_fd(ssh, &c->wfd);
if (efd != sock && efd != rfd && efd != wfd)
channel_close_fd(ssh, &c->efd);
}
static void
fwd_perm_clear(struct permission *perm)
{
free(perm->host_to_connect);
free(perm->listen_host);
free(perm->listen_path);
memset(perm, 0, sizeof(*perm));
}
/* Returns an printable name for the specified forwarding permission list */
static const char *
fwd_ident(int who, int where)
{
if (who == FORWARD_ADM) {
if (where == FORWARD_LOCAL)
return "admin local";
else if (where == FORWARD_REMOTE)
return "admin remote";
} else if (who == FORWARD_USER) {
if (where == FORWARD_LOCAL)
return "user local";
else if (where == FORWARD_REMOTE)
return "user remote";
}
fatal("Unknown forward permission list %d/%d", who, where);
}
/* Returns the forwarding permission list for the specified direction */
static struct permission_set *
permission_set_get(struct ssh *ssh, int where)
{
struct ssh_channels *sc = ssh->chanctxt;
switch (where) {
case FORWARD_LOCAL:
return &sc->local_perms;
break;
case FORWARD_REMOTE:
return &sc->remote_perms;
break;
default:
fatal("%s: invalid forwarding direction %d", __func__, where);
}
}
/* Returns pointers to the specified forwarding list and its element count */
static void
permission_set_get_array(struct ssh *ssh, int who, int where,
struct permission ***permpp, u_int **npermpp)
{
struct permission_set *pset = permission_set_get(ssh, where);
switch (who) {
case FORWARD_USER:
*permpp = &pset->permitted_user;
*npermpp = &pset->num_permitted_user;
break;
case FORWARD_ADM:
*permpp = &pset->permitted_admin;
*npermpp = &pset->num_permitted_admin;
break;
default:
fatal("%s: invalid forwarding client %d", __func__, who);
}
}
/* Adds an entry to the spcified forwarding list */
static int
permission_set_add(struct ssh *ssh, int who, int where,
const char *host_to_connect, int port_to_connect,
const char *listen_host, const char *listen_path, int listen_port,
Channel *downstream)
{
struct permission **permp;
u_int n, *npermp;
permission_set_get_array(ssh, who, where, &permp, &npermp);
if (*npermp >= INT_MAX)
fatal("%s: %s overflow", __func__, fwd_ident(who, where));
*permp = xrecallocarray(*permp, *npermp, *npermp + 1, sizeof(**permp));
n = (*npermp)++;
#define MAYBE_DUP(s) ((s == NULL) ? NULL : xstrdup(s))
(*permp)[n].host_to_connect = MAYBE_DUP(host_to_connect);
(*permp)[n].port_to_connect = port_to_connect;
(*permp)[n].listen_host = MAYBE_DUP(listen_host);
(*permp)[n].listen_path = MAYBE_DUP(listen_path);
(*permp)[n].listen_port = listen_port;
(*permp)[n].downstream = downstream;
#undef MAYBE_DUP
return (int)n;
}
static void
mux_remove_remote_forwardings(struct ssh *ssh, Channel *c)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
struct permission *perm;
int r;
u_int i;
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (perm->downstream != c)
continue;
/* cancel on the server, since mux client is gone */
debug("channel %d: cleanup remote forward for %s:%u",
c->self, perm->listen_host, perm->listen_port);
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh,
"cancel-tcpip-forward")) != 0 ||
(r = sshpkt_put_u8(ssh, 0)) != 0 ||
(r = sshpkt_put_cstring(ssh,
channel_rfwd_bind_host(perm->listen_host))) != 0 ||
(r = sshpkt_put_u32(ssh, perm->listen_port)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: %s", __func__,
c->self, ssh_err(r));
}
fwd_perm_clear(perm); /* unregister */
}
}
/* Free the channel and close its fd/socket. */
void
channel_free(struct ssh *ssh, Channel *c)
{
struct ssh_channels *sc = ssh->chanctxt;
char *s;
u_int i, n;
Channel *other;
struct channel_confirm *cc;
for (n = 0, i = 0; i < sc->channels_alloc; i++) {
if ((other = sc->channels[i]) == NULL)
continue;
n++;
/* detach from mux client and prepare for closing */
if (c->type == SSH_CHANNEL_MUX_CLIENT &&
other->type == SSH_CHANNEL_MUX_PROXY &&
other->mux_ctx == c) {
other->mux_ctx = NULL;
other->type = SSH_CHANNEL_OPEN;
other->istate = CHAN_INPUT_CLOSED;
other->ostate = CHAN_OUTPUT_CLOSED;
}
}
debug("channel %d: free: %s, nchannels %u", c->self,
c->remote_name ? c->remote_name : "???", n);
if (c->type == SSH_CHANNEL_MUX_CLIENT)
mux_remove_remote_forwardings(ssh, c);
if (log_level_get() >= SYSLOG_LEVEL_DEBUG3) {
s = channel_open_message(ssh);
debug3("channel %d: status: %s", c->self, s);
free(s);
}
channel_close_fds(ssh, c);
sshbuf_free(c->input);
sshbuf_free(c->output);
sshbuf_free(c->extended);
c->input = c->output = c->extended = NULL;
free(c->remote_name);
c->remote_name = NULL;
free(c->path);
c->path = NULL;
free(c->listening_addr);
c->listening_addr = NULL;
while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
if (cc->abandon_cb != NULL)
cc->abandon_cb(ssh, c, cc->ctx);
TAILQ_REMOVE(&c->status_confirms, cc, entry);
freezero(cc, sizeof(*cc));
}
if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
c->filter_cleanup(ssh, c->self, c->filter_ctx);
sc->channels[c->self] = NULL;
freezero(c, sizeof(*c));
}
void
channel_free_all(struct ssh *ssh)
{
u_int i;
struct ssh_channels *sc = ssh->chanctxt;
for (i = 0; i < sc->channels_alloc; i++)
if (sc->channels[i] != NULL)
channel_free(ssh, sc->channels[i]);
free(sc->channels);
sc->channels = NULL;
sc->channels_alloc = 0;
sc->channel_max_fd = 0;
free(sc->x11_saved_display);
sc->x11_saved_display = NULL;
free(sc->x11_saved_proto);
sc->x11_saved_proto = NULL;
free(sc->x11_saved_data);
sc->x11_saved_data = NULL;
sc->x11_saved_data_len = 0;
free(sc->x11_fake_data);
sc->x11_fake_data = NULL;
sc->x11_fake_data_len = 0;
}
/*
* Closes the sockets/fds of all channels. This is used to close extra file
* descriptors after a fork.
*/
void
channel_close_all(struct ssh *ssh)
{
u_int i;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++)
if (ssh->chanctxt->channels[i] != NULL)
channel_close_fds(ssh, ssh->chanctxt->channels[i]);
}
/*
* Stop listening to channels.
*/
void
channel_stop_listening(struct ssh *ssh)
{
u_int i;
Channel *c;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c != NULL) {
switch (c->type) {
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
channel_close_fd(ssh, &c->sock);
channel_free(ssh, 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(struct ssh *ssh)
{
u_int i;
u_int maxsize = ssh_packet_get_maxsize(ssh);
Channel *c;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c == NULL || c->type != SSH_CHANNEL_OPEN)
continue;
if (sshbuf_len(c->output) > maxsize) {
debug2("channel %d: big output buffer %zu > %u",
c->self, sshbuf_len(c->output), maxsize);
return 0;
}
}
return 1;
}
/* Returns true if any channel is still open. */
int
channel_still_open(struct ssh *ssh)
{
u_int i;
Channel *c;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->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_RDYNAMIC_OPEN:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
continue;
case SSH_CHANNEL_LARVAL:
continue;
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_RDYNAMIC_FINISH:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_MUX_CLIENT:
case SSH_CHANNEL_MUX_PROXY:
return 1;
default:
fatal("%s: bad channel type %d", __func__, c->type);
/* NOTREACHED */
}
}
return 0;
}
/* Returns the id of an open channel suitable for keepaliving */
int
channel_find_open(struct ssh *ssh)
{
u_int i;
Channel *c;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c == NULL || !c->have_remote_id)
continue;
switch (c->type) {
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_RDYNAMIC_OPEN:
case SSH_CHANNEL_RDYNAMIC_FINISH:
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_MUX_LISTENER:
case SSH_CHANNEL_MUX_CLIENT:
case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
continue;
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
return i;
default:
fatal("%s: bad channel type %d", __func__, c->type);
/* NOTREACHED */
}
}
return -1;
}
/* Returns the state of the channel's extended usage flag */
const char *
channel_format_extended_usage(const Channel *c)
{
if (c->efd == -1)
return "closed";
switch (c->extended_usage) {
case CHAN_EXTENDED_WRITE:
return "write";
case CHAN_EXTENDED_READ:
return "read";
case CHAN_EXTENDED_IGNORE:
return "ignore";
default:
return "UNKNOWN";
}
}
static char *
channel_format_status(const Channel *c)
{
char *ret = NULL;
xasprintf(&ret, "t%d %s%u i%u/%zu o%u/%zu e[%s]/%zu "
"fd %d/%d/%d sock %d cc %d",
c->type,
c->have_remote_id ? "r" : "nr", c->remote_id,
c->istate, sshbuf_len(c->input),
c->ostate, sshbuf_len(c->output),
channel_format_extended_usage(c), sshbuf_len(c->extended),
c->rfd, c->wfd, c->efd, c->sock, c->ctl_chan);
return ret;
}
/*
* 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(struct ssh *ssh)
{
struct sshbuf *buf;
Channel *c;
u_int i;
int r;
char *cp, *ret;
if ((buf = sshbuf_new()) == NULL)
fatal("%s: sshbuf_new", __func__);
if ((r = sshbuf_putf(buf,
"The following connections are open:\r\n")) != 0)
fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
c = ssh->chanctxt->channels[i];
if (c == NULL)
continue;
switch (c->type) {
case SSH_CHANNEL_X11_LISTENER:
case SSH_CHANNEL_PORT_LISTENER:
case SSH_CHANNEL_RPORT_LISTENER:
case SSH_CHANNEL_CLOSED:
case SSH_CHANNEL_AUTH_SOCKET:
case SSH_CHANNEL_ZOMBIE:
case SSH_CHANNEL_ABANDONED:
case SSH_CHANNEL_MUX_LISTENER:
case SSH_CHANNEL_UNIX_LISTENER:
case SSH_CHANNEL_RUNIX_LISTENER:
continue;
case SSH_CHANNEL_LARVAL:
case SSH_CHANNEL_OPENING:
case SSH_CHANNEL_CONNECTING:
case SSH_CHANNEL_DYNAMIC:
case SSH_CHANNEL_RDYNAMIC_OPEN:
case SSH_CHANNEL_RDYNAMIC_FINISH:
case SSH_CHANNEL_OPEN:
case SSH_CHANNEL_X11_OPEN:
case SSH_CHANNEL_MUX_PROXY:
case SSH_CHANNEL_MUX_CLIENT:
cp = channel_format_status(c);
if ((r = sshbuf_putf(buf, " #%d %.300s (%s)\r\n",
c->self, c->remote_name, cp)) != 0) {
free(cp);
fatal("%s: sshbuf_putf: %s",
__func__, ssh_err(r));
}
free(cp);
continue;
default:
fatal("%s: bad channel type %d", __func__, c->type);
/* NOTREACHED */
}
}
if ((ret = sshbuf_dup_string(buf)) == NULL)
fatal("%s: sshbuf_dup_string", __func__);
sshbuf_free(buf);
return ret;
}
static void
open_preamble(struct ssh *ssh, const char *where, Channel *c, const char *type)
{
int r;
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
(r = sshpkt_put_cstring(ssh, type)) != 0 ||
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) {
fatal("%s: channel %i: open: %s", where, c->self, ssh_err(r));
}
}
void
channel_send_open(struct ssh *ssh, int id)
{
Channel *c = channel_lookup(ssh, id);
int r;
if (c == NULL) {
logit("channel_send_open: %d: bad id", id);
return;
}
debug2("channel %d: send open", id);
open_preamble(ssh, __func__, c, c->ctype);
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
}
void
channel_request_start(struct ssh *ssh, int id, char *service, int wantconfirm)
{
Channel *c = channel_lookup(ssh, id);
int r;
if (c == NULL) {
logit("%s: %d: unknown channel id", __func__, id);
return;
}
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_cstring(ssh, service)) != 0 ||
(r = sshpkt_put_u8(ssh, wantconfirm)) != 0) {
fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
}
}
void
channel_register_status_confirm(struct ssh *ssh, int id,
channel_confirm_cb *cb, channel_confirm_abandon_cb *abandon_cb, void *ctx)
{
struct channel_confirm *cc;
Channel *c;
if ((c = channel_lookup(ssh, id)) == NULL)
fatal("%s: %d: bad id", __func__, id);
cc = xcalloc(1, sizeof(*cc));
cc->cb = cb;
cc->abandon_cb = abandon_cb;
cc->ctx = ctx;
TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry);
}
void
channel_register_open_confirm(struct ssh *ssh, int id,
channel_open_fn *fn, void *ctx)
{
Channel *c = channel_lookup(ssh, id);
if (c == NULL) {
logit("%s: %d: bad id", __func__, id);
return;
}
c->open_confirm = fn;
c->open_confirm_ctx = ctx;
}
void
channel_register_cleanup(struct ssh *ssh, int id,
channel_callback_fn *fn, int do_close)
{
Channel *c = channel_by_id(ssh, id);
if (c == NULL) {
logit("%s: %d: bad id", __func__, id);
return;
}
c->detach_user = fn;
c->detach_close = do_close;
}
void
channel_cancel_cleanup(struct ssh *ssh, int id)
{
Channel *c = channel_by_id(ssh, id);
if (c == NULL) {
logit("%s: %d: bad id", __func__, id);
return;
}
c->detach_user = NULL;
c->detach_close = 0;
}
void
channel_register_filter(struct ssh *ssh, int id, channel_infilter_fn *ifn,
channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
{
Channel *c = channel_lookup(ssh, id);
if (c == NULL) {
logit("%s: %d: bad id", __func__, id);
return;
}
c->input_filter = ifn;
c->output_filter = ofn;
c->filter_ctx = ctx;
c->filter_cleanup = cfn;
}
void
channel_set_fds(struct ssh *ssh, int id, int rfd, int wfd, int efd,
int extusage, int nonblock, int is_tty, u_int window_max)
{
Channel *c = channel_lookup(ssh, id);
int r;
if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
fatal("channel_activate for non-larval channel %d.", id);
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, is_tty);
c->type = SSH_CHANNEL_OPEN;
c->local_window = c->local_window_max = window_max;
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
}
static void
channel_pre_listener(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
FD_SET(c->sock, readset);
}
static void
channel_pre_connecting(struct ssh *ssh, 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(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
if (c->istate == CHAN_INPUT_OPEN &&
c->remote_window > 0 &&
sshbuf_len(c->input) < c->remote_window &&
sshbuf_check_reserve(c->input, CHAN_RBUF) == 0)
FD_SET(c->rfd, readset);
if (c->ostate == CHAN_OUTPUT_OPEN ||
c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
if (sshbuf_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/(%zu)", c->self,
c->efd, sshbuf_len(c->extended));
else
chan_obuf_empty(ssh, c);
}
}
/** XXX check close conditions, too */
if (c->efd != -1 && !(c->istate == CHAN_INPUT_CLOSED &&
c->ostate == CHAN_OUTPUT_CLOSED)) {
if (c->extended_usage == CHAN_EXTENDED_WRITE &&
sshbuf_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) &&
sshbuf_len(c->extended) < c->remote_window)
FD_SET(c->efd, readset);
}
/* XXX: What about efd? races? */
}
/*
* This is a special state for X11 authentication spoofing. An opened X11
* connection (when authentication spoofing is being done) remains in this
* state until the first packet has been completely read. The authentication
* data in that packet is then substituted by the real data if it matches the
* fake data, and the channel is put into normal mode.
* XXX All this happens at the client side.
* Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
*/
static int
x11_open_helper(struct ssh *ssh, struct sshbuf *b)
{
struct ssh_channels *sc = ssh->chanctxt;
u_char *ucp;
u_int proto_len, data_len;
/* Is this being called after the refusal deadline? */
if (sc->x11_refuse_time != 0 &&
(u_int)monotime() >= sc->x11_refuse_time) {
verbose("Rejected X11 connection after ForwardX11Timeout "
"expired");
return -1;
}
/* Check if the fixed size part of the packet is in buffer. */
if (sshbuf_len(b) < 12)
return 0;
/* Parse the lengths of variable-length fields. */
ucp = sshbuf_mutable_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 (sshbuf_len(b) <
12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
return 0;
/* Check if authentication protocol matches. */
if (proto_len != strlen(sc->x11_saved_proto) ||
memcmp(ucp + 12, sc->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 != sc->x11_fake_data_len ||
timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
sc->x11_fake_data, sc->x11_fake_data_len) != 0) {
debug2("X11 auth data does not match fake data.");
return -1;
}
/* Check fake data length */
if (sc->x11_fake_data_len != sc->x11_saved_data_len) {
error("X11 fake_data_len %d != saved_data_len %d",
sc->x11_fake_data_len, sc->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),
sc->x11_saved_data, sc->x11_saved_data_len);
return 1;
}
static void
channel_pre_x11_open(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
int ret = x11_open_helper(ssh, c->output);
/* c->force_drain = 1; */
if (ret == 1) {
c->type = SSH_CHANNEL_OPEN;
channel_pre_open(ssh, 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(ssh, c);
sshbuf_reset(c->input);
chan_ibuf_empty(ssh, c);
sshbuf_reset(c->output);
chan_write_failed(ssh, c);
debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
}
}
static void
channel_pre_mux_client(struct ssh *ssh,
Channel *c, fd_set *readset, fd_set *writeset)
{
if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
sshbuf_check_reserve(c->input, CHAN_RBUF) == 0)
FD_SET(c->rfd, readset);
if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
/* clear buffer immediately (discard any partial packet) */
sshbuf_reset(c->input);
chan_ibuf_empty(ssh, c);
/* Start output drain. XXX just kill chan? */
chan_rcvd_oclose(ssh, c);
}
if (c->ostate == CHAN_OUTPUT_OPEN ||
c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
if (sshbuf_len(c->output) > 0)
FD_SET(c->wfd, writeset);
else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
chan_obuf_empty(ssh, c);
}
}
/* try to decode a socks4 header */
static int
channel_decode_socks4(Channel *c, struct sshbuf *input, struct sshbuf *output)
{
const u_char *p;
char *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;
int r;
debug2("channel %d: decode socks4", c->self);
have = sshbuf_len(input);
len = sizeof(s4_req);
if (have < len)
return 0;
p = sshbuf_ptr(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;
if ((r = sshbuf_get(input, &s4_req.version, 1)) != 0 ||
(r = sshbuf_get(input, &s4_req.command, 1)) != 0 ||
(r = sshbuf_get(input, &s4_req.dest_port, 2)) != 0 ||
(r = sshbuf_get(input, &s4_req.dest_addr, 4)) != 0) {
debug("channels %d: decode socks4: %s", c->self, ssh_err(r));
return -1;
}
have = sshbuf_len(input);
p = sshbuf_ptr(input);
if (memchr(p, '\0', have) == NULL) {
error("channel %d: decode socks4: user not nul terminated",
c->self);
return -1;
}
len = strlen(p);
debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
len++; /* trailing '\0' */
strlcpy(username, p, sizeof(username));
if ((r = sshbuf_consume(input, len)) != 0) {
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
free(c->path);
c->path = NULL;
if (need == 1) { /* SOCKS4: one string */
host = inet_ntoa(s4_req.dest_addr);
c->path = xstrdup(host);
} else { /* SOCKS4A: two strings */
have = sshbuf_len(input);
p = sshbuf_ptr(input);
if (memchr(p, '\0', have) == NULL) {
error("channel %d: decode socks4a: host not nul "
"terminated", c->self);
return -1;
}
len = strlen(p);
debug2("channel %d: decode socks4a: host %s/%d",
c->self, p, len);
len++; /* trailing '\0' */
if (len > NI_MAXHOST) {
error("channel %d: hostname \"%.100s\" too long",
c->self, p);
return -1;
}
c->path = xstrdup(p);
if ((r = sshbuf_consume(input, len)) != 0) {
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
}
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 */
if ((r = sshbuf_put(output, &s4_rsp, sizeof(s4_rsp))) != 0) {
fatal("%s: channel %d: append reply: %s", __func__,
c->self, ssh_err(r));
}
return 1;
}
/* try to decode a socks5 header */
#define SSH_SOCKS5_AUTHDONE 0x1000
#define SSH_SOCKS5_NOAUTH 0x00
#define SSH_SOCKS5_IPV4 0x01
#define SSH_SOCKS5_DOMAIN 0x03
#define SSH_SOCKS5_IPV6 0x04
#define SSH_SOCKS5_CONNECT 0x01
#define SSH_SOCKS5_SUCCESS 0x00
static int
channel_decode_socks5(Channel *c, struct sshbuf *input, struct sshbuf *output)
{
/* XXX use get/put_u8 instead of trusting struct padding */
struct {
u_int8_t version;
u_int8_t command;
u_int8_t reserved;
u_int8_t atyp;
} s5_req, s5_rsp;
u_int16_t dest_port;
char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
const u_char *p;
u_int have, need, i, found, nmethods, addrlen, af;
int r;
debug2("channel %d: decode socks5", c->self);
p = sshbuf_ptr(input);
if (p[0] != 0x05)
return -1;
have = sshbuf_len(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;
}
if ((r = sshbuf_consume(input, nmethods + 2)) != 0) {
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
/* version, method */
if ((r = sshbuf_put_u8(output, 0x05)) != 0 ||
(r = sshbuf_put_u8(output, SSH_SOCKS5_NOAUTH)) != 0) {
fatal("%s: channel %d: append reply: %s", __func__,
c->self, ssh_err(r));
}
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;
if ((r = sshbuf_consume(input, sizeof(s5_req))) != 0) {
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
/* host string length */
if ((r = sshbuf_consume(input, 1)) != 0) {
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
}
if ((r = sshbuf_get(input, &dest_addr, addrlen)) != 0 ||
(r = sshbuf_get(input, &dest_port, 2)) != 0) {
debug("channel %d: parse addr/port: %s", c->self, ssh_err(r));
return -1;
}
dest_addr[addrlen] = '\0';
free(c->path);
c->path = NULL;
if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
if (addrlen >= NI_MAXHOST) {
error("channel %d: dynamic request: socks5 hostname "
"\"%.100s\" too long", c->self, dest_addr);
return -1;
}
c->path = xstrdup(dest_addr);
} else {
if (inet_ntop(af, dest_addr, ntop, sizeof(ntop)) == NULL)
return -1;
c->path = xstrdup(ntop);
}
c->host_port = ntohs(dest_port);
debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
c->self, c->path, c->host_port, s5_req.command);
s5_rsp.version = 0x05;
s5_rsp.command = SSH_SOCKS5_SUCCESS;
s5_rsp.reserved = 0; /* ignored */
s5_rsp.atyp = SSH_SOCKS5_IPV4;
dest_port = 0; /* ignored */
if ((r = sshbuf_put(output, &s5_rsp, sizeof(s5_rsp))) != 0 ||
(r = sshbuf_put_u32(output, ntohl(INADDR_ANY))) != 0 ||
(r = sshbuf_put(output, &dest_port, sizeof(dest_port))) != 0)
fatal("%s: channel %d: append reply: %s", __func__,
c->self, ssh_err(r));
return 1;
}
Channel *
channel_connect_stdio_fwd(struct ssh *ssh,
const char *host_to_connect, u_short port_to_connect, int in, int out)
{
Channel *c;
debug("%s %s:%d", __func__, host_to_connect, port_to_connect);
c = channel_new(ssh, "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(ssh, c, in, out, -1, 0, 1, 0);
port_open_helper(ssh, c, "direct-tcpip");
return c;
}
/* dynamic port forwarding */
static void
channel_pre_dynamic(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
const u_char *p;
u_int have;
int ret;
have = sshbuf_len(c->input);
debug2("channel %d: pre_dynamic: have %d", c->self, have);
/* sshbuf_dump(c->input, stderr); */
/* 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 = sshbuf_ptr(c->input);
/* XXX sshbuf_peek_u8? */
switch (p[0]) {
case 0x04:
ret = channel_decode_socks4(c, c->input, c->output);
break;
case 0x05:
ret = channel_decode_socks5(c, c->input, c->output);
break;
default:
ret = -1;
break;
}
if (ret < 0) {
chan_mark_dead(ssh, c);
} else if (ret == 0) {
debug2("channel %d: pre_dynamic: need more", c->self);
/* need more */
FD_SET(c->sock, readset);
if (sshbuf_len(c->output))
FD_SET(c->sock, writeset);
} else {
/* switch to the next state */
c->type = SSH_CHANNEL_OPENING;
port_open_helper(ssh, c, "direct-tcpip");
}
}
/* simulate read-error */
static void
rdynamic_close(struct ssh *ssh, Channel *c)
{
c->type = SSH_CHANNEL_OPEN;
chan_read_failed(ssh, c);
sshbuf_reset(c->input);
chan_ibuf_empty(ssh, c);
sshbuf_reset(c->output);
chan_write_failed(ssh, c);
}
/* reverse dynamic port forwarding */
static void
channel_before_prepare_select_rdynamic(struct ssh *ssh, Channel *c)
{
const u_char *p;
u_int have, len;
int r, ret;
have = sshbuf_len(c->output);
debug2("channel %d: pre_rdynamic: have %d", c->self, have);
/* sshbuf_dump(c->output, stderr); */
/* EOF received */
if (c->flags & CHAN_EOF_RCVD) {
if ((r = sshbuf_consume(c->output, have)) != 0) {
fatal("%s: channel %d: consume: %s",
__func__, c->self, ssh_err(r));
}
rdynamic_close(ssh, c);
return;
}
/* check if the fixed size part of the packet is in buffer. */
if (have < 3)
return;
/* try to guess the protocol */
p = sshbuf_ptr(c->output);
switch (p[0]) {
case 0x04:
/* switch input/output for reverse forwarding */
ret = channel_decode_socks4(c, c->output, c->input);
break;
case 0x05:
ret = channel_decode_socks5(c, c->output, c->input);
break;
default:
ret = -1;
break;
}
if (ret < 0) {
rdynamic_close(ssh, c);
} else if (ret == 0) {
debug2("channel %d: pre_rdynamic: need more", c->self);
/* send socks request to peer */
len = sshbuf_len(c->input);
if (len > 0 && len < c->remote_window) {
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_stringb(ssh, c->input)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: rdynamic: %s", __func__,
c->self, ssh_err(r));
}
if ((r = sshbuf_consume(c->input, len)) != 0) {
fatal("%s: channel %d: consume: %s",
__func__, c->self, ssh_err(r));
}
c->remote_window -= len;
}
} else if (rdynamic_connect_finish(ssh, c) < 0) {
/* the connect failed */
rdynamic_close(ssh, c);
}
}
/* This is our fake X11 server socket. */
static void
channel_post_x11_listener(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
Channel *nc;
struct sockaddr_storage addr;
int r, newsock, oerrno, remote_port;
socklen_t addrlen;
char buf[16384], *remote_ipaddr;
if (!FD_ISSET(c->sock, readset))
return;
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(ssh, &c->sock);
chan_mark_dead(ssh, c);
errno = oerrno;
}
if (newsock == -1) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
set_nodelay(newsock);
remote_ipaddr = get_peer_ipaddr(newsock);
remote_port = get_peer_port(newsock);
snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
remote_ipaddr, remote_port);
nc = channel_new(ssh, "accepted x11 socket",
SSH_CHANNEL_OPENING, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket, 0, buf, 1);
open_preamble(ssh, __func__, nc, "x11");
if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0 ||
(r = sshpkt_put_u32(ssh, remote_port)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
free(remote_ipaddr);
}
static void
port_open_helper(struct ssh *ssh, Channel *c, char *rtype)
{
char *local_ipaddr = get_local_ipaddr(c->sock);
int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock);
char *remote_ipaddr = get_peer_ipaddr(c->sock);
int remote_port = get_peer_port(c->sock);
int r;
if (remote_port == -1) {
/* Fake addr/port to appease peers that validate it (Tectia) */
free(remote_ipaddr);
remote_ipaddr = xstrdup("127.0.0.1");
remote_port = 65535;
}
free(c->remote_name);
xasprintf(&c->remote_name,
"%s: listening port %d for %.100s port %d, "
"connect from %.200s port %d to %.100s port %d",
rtype, c->listening_port, c->path, c->host_port,
remote_ipaddr, remote_port, local_ipaddr, local_port);
open_preamble(ssh, __func__, c, rtype);
if (strcmp(rtype, "direct-tcpip") == 0) {
/* target host, port */
if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 ||
(r = sshpkt_put_u32(ssh, c->host_port)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
} else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
/* target path */
if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
} else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
/* listen path */
if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
} else {
/* listen address, port */
if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 ||
(r = sshpkt_put_u32(ssh, local_port)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
}
if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
/* reserved for future owner/mode info */
if ((r = sshpkt_put_cstring(ssh, "")) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
} else {
/* originator host and port */
if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)remote_port)) != 0) {
fatal("%s: channel %i: reply %s", __func__,
c->self, ssh_err(r));
}
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
free(remote_ipaddr);
free(local_ipaddr);
}
void
channel_set_x11_refuse_time(struct ssh *ssh, u_int refuse_time)
{
ssh->chanctxt->x11_refuse_time = refuse_time;
}
/*
* This socket is listening for connections to a forwarded TCP/IP port.
*/
static void
channel_post_port_listener(struct ssh *ssh, 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))
return;
debug("Connection to port %d forwarding to %.100s port %d requested.",
c->listening_port, c->path, c->host_port);
if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "forwarded-tcpip";
} else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "forwarded-streamlocal@openssh.com";
} else if (c->host_port == PORT_STREAMLOCAL) {
nextstate = SSH_CHANNEL_OPENING;
rtype = "direct-streamlocal@openssh.com";
} else if (c->host_port == 0) {
nextstate = SSH_CHANNEL_DYNAMIC;
rtype = "dynamic-tcpip";
} else {
nextstate = SSH_CHANNEL_OPENING;
rtype = "direct-tcpip";
}
addrlen = sizeof(addr);
newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
if (newsock == -1) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
if (c->host_port != PORT_STREAMLOCAL)
set_nodelay(newsock);
nc = channel_new(ssh, 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(ssh, nc, rtype);
}
/*
* This is the authentication agent socket listening for connections from
* clients.
*/
static void
channel_post_auth_listener(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
Channel *nc;
int r, newsock;
struct sockaddr_storage addr;
socklen_t addrlen;
if (!FD_ISSET(c->sock, readset))
return;
addrlen = sizeof(addr);
newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
if (newsock == -1) {
error("accept from auth socket: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
nc = channel_new(ssh, "accepted auth socket",
SSH_CHANNEL_OPENING, newsock, newsock, -1,
c->local_window_max, c->local_maxpacket,
0, "accepted auth socket", 1);
open_preamble(ssh, __func__, nc, "auth-agent@openssh.com");
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
}
static void
channel_post_connecting(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
int err = 0, sock, isopen, r;
socklen_t sz = sizeof(err);
if (!FD_ISSET(c->sock, writeset))
return;
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
/* for rdynamic the OPEN_CONFIRMATION has been sent already */
isopen = (c->type == SSH_CHANNEL_RDYNAMIC_FINISH);
if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) == -1) {
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 (isopen) {
/* no message necessary */
} else {
if ((r = sshpkt_start(ssh,
SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_maxpacket))
!= 0)
fatal("%s: channel %i: confirm: %s", __func__,
c->self, ssh_err(r));
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: %s", __func__, c->self,
ssh_err(r));
}
} 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_find_maxfd(ssh->chanctxt);
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 (isopen) {
rdynamic_close(ssh, c);
} else {
if ((r = sshpkt_start(ssh,
SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh,
SSH2_OPEN_CONNECT_FAILED)) != 0 ||
(r = sshpkt_put_cstring(ssh, strerror(err))) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0) {
fatal("%s: channel %i: failure: %s", __func__,
c->self, ssh_err(r));
}
if ((r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %i: %s", __func__, c->self,
ssh_err(r));
chan_mark_dead(ssh, c);
}
}
}
static int
channel_handle_rfd(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
char buf[CHAN_RBUF];
ssize_t len;
int r, force;
force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
if (c->rfd == -1 || (!force && !FD_ISSET(c->rfd, readset)))
return 1;
errno = 0;
len = read(c->rfd, buf, sizeof(buf));
if (len == -1 && (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 %zd",
c->self, c->rfd, len);
if (c->type != SSH_CHANNEL_OPEN) {
debug2("channel %d: not open", c->self);
chan_mark_dead(ssh, c);
return -1;
} else {
chan_read_failed(ssh, c);
}
return -1;
}
if (c->input_filter != NULL) {
if (c->input_filter(ssh, c, buf, len) == -1) {
debug2("channel %d: filter stops", c->self);
chan_read_failed(ssh, c);
}
} else if (c->datagram) {
if ((r = sshbuf_put_string(c->input, buf, len)) != 0)
fatal("%s: channel %d: put datagram: %s", __func__,
c->self, ssh_err(r));
} else if ((r = sshbuf_put(c->input, buf, len)) != 0) {
fatal("%s: channel %d: put data: %s", __func__,
c->self, ssh_err(r));
}
return 1;
}
static int
channel_handle_wfd(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
struct termios tio;
u_char *data = NULL, *buf; /* XXX const; need filter API change */
size_t dlen, olen = 0;
int r, len;
if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) ||
sshbuf_len(c->output) == 0)
return 1;
/* Send buffered output data to the socket. */
olen = sshbuf_len(c->output);
if (c->output_filter != NULL) {
if ((buf = c->output_filter(ssh, c, &data, &dlen)) == NULL) {
debug2("channel %d: filter stops", c->self);
if (c->type != SSH_CHANNEL_OPEN)
chan_mark_dead(ssh, c);
else
chan_write_failed(ssh, c);
return -1;
}
} else if (c->datagram) {
if ((r = sshbuf_get_string(c->output, &data, &dlen)) != 0)
fatal("%s: channel %d: get datagram: %s", __func__,
c->self, ssh_err(r));
buf = data;
} else {
buf = data = sshbuf_mutable_ptr(c->output);
dlen = sshbuf_len(c->output);
}
if (c->datagram) {
/* ignore truncated writes, datagrams might get lost */
len = write(c->wfd, buf, dlen);
free(data);
if (len == -1 && (errno == EINTR || errno == EAGAIN ||
errno == EWOULDBLOCK))
return 1;
if (len <= 0)
goto write_fail;
goto out;
}
#ifdef _AIX
/* XXX: Later AIX versions can't push as much data to tty */
if (c->wfd_isatty)
dlen = MIN(dlen, 8*1024);
#endif
len = write(c->wfd, buf, dlen);
if (len == -1 &&
(errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
return 1;
if (len <= 0) {
write_fail:
if (c->type != SSH_CHANNEL_OPEN) {
debug2("channel %d: not open", c->self);
chan_mark_dead(ssh, c);
return -1;
} else {
chan_write_failed(ssh, c);
}
return -1;
}
#ifndef BROKEN_TCGETATTR_ICANON
if (c->isatty && dlen >= 1 && buf[0] != '\r') {
if (tcgetattr(c->wfd, &tio) == 0 &&
!(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
/*
* Simulate echo to reduce the impact of
* traffic analysis. We need to match the
* size of a SSH2_MSG_CHANNEL_DATA message
* (4 byte channel id + buf)
*/
if ((r = sshpkt_msg_ignore(ssh, 4+len)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %d: ignore: %s",
__func__, c->self, ssh_err(r));
}
}
#endif /* BROKEN_TCGETATTR_ICANON */
if ((r = sshbuf_consume(c->output, len)) != 0) {
fatal("%s: channel %d: consume: %s",
__func__, c->self, ssh_err(r));
}
out:
c->local_consumed += olen - sshbuf_len(c->output);
return 1;
}
static int
channel_handle_efd_write(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
int r;
ssize_t len;
if (!FD_ISSET(c->efd, writeset) || sshbuf_len(c->extended) == 0)
return 1;
len = write(c->efd, sshbuf_ptr(c->extended),
sshbuf_len(c->extended));
debug2("channel %d: written %zd to efd %d", c->self, len, c->efd);
if (len == -1 && (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(ssh, &c->efd);
} else {
if ((r = sshbuf_consume(c->extended, len)) != 0) {
fatal("%s: channel %d: consume: %s",
__func__, c->self, ssh_err(r));
}
c->local_consumed += len;
}
return 1;
}
static int
channel_handle_efd_read(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
char buf[CHAN_RBUF];
ssize_t len;
int r, force;
force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
if (c->efd == -1 || (!force && !FD_ISSET(c->efd, readset)))
return 1;
len = read(c->efd, buf, sizeof(buf));
debug2("channel %d: read %zd from efd %d", c->self, len, c->efd);
if (len == -1 && (errno == EINTR || ((errno == EAGAIN ||
errno == EWOULDBLOCK) && !force)))
return 1;
if (len <= 0) {
debug2("channel %d: closing read-efd %d",
c->self, c->efd);
channel_close_fd(ssh, &c->efd);
} else {
if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
debug3("channel %d: discard efd",
c->self);
} else if ((r = sshbuf_put(c->extended, buf, len)) != 0) {
fatal("%s: channel %d: append: %s",
__func__, c->self, ssh_err(r));
}
}
return 1;
}
static int
channel_handle_efd(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
if (c->efd == -1)
return 1;
/** XXX handle drain efd, too */
if (c->extended_usage == CHAN_EXTENDED_WRITE)
return channel_handle_efd_write(ssh, c, readset, writeset);
else if (c->extended_usage == CHAN_EXTENDED_READ ||
c->extended_usage == CHAN_EXTENDED_IGNORE)
return channel_handle_efd_read(ssh, c, readset, writeset);
return 1;
}
static int
channel_check_window(struct ssh *ssh, Channel *c)
{
int r;
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) {
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id",
__func__, c->self);
if ((r = sshpkt_start(ssh,
SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_consumed)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: %s", __func__,
c->self, ssh_err(r));
}
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(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
channel_handle_rfd(ssh, c, readset, writeset);
channel_handle_wfd(ssh, c, readset, writeset);
channel_handle_efd(ssh, c, readset, writeset);
channel_check_window(ssh, c);
}
static u_int
read_mux(struct ssh *ssh, Channel *c, u_int need)
{
char buf[CHAN_RBUF];
ssize_t len;
u_int rlen;
int r;
if (sshbuf_len(c->input) < need) {
rlen = need - sshbuf_len(c->input);
len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
if (len == -1 && (errno == EINTR || errno == EAGAIN))
return sshbuf_len(c->input);
if (len <= 0) {
debug2("channel %d: ctl read<=0 rfd %d len %zd",
c->self, c->rfd, len);
chan_read_failed(ssh, c);
return 0;
} else if ((r = sshbuf_put(c->input, buf, len)) != 0) {
fatal("%s: channel %d: append: %s",
__func__, c->self, ssh_err(r));
}
}
return sshbuf_len(c->input);
}
static void
channel_post_mux_client_read(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
u_int need;
if (c->rfd == -1 || !FD_ISSET(c->rfd, readset))
return;
if (c->istate != CHAN_INPUT_OPEN && c->istate != CHAN_INPUT_WAIT_DRAIN)
return;
if (c->mux_pause)
return;
/*
* Don't not read past the precise end of packets to
* avoid disrupting fd passing.
*/
if (read_mux(ssh, c, 4) < 4) /* read header */
return;
/* XXX sshbuf_peek_u32 */
need = PEEK_U32(sshbuf_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(ssh, c);
return;
}
if (read_mux(ssh, c, need + 4) < need + 4) /* read body */
return;
if (c->mux_rcb(ssh, c) != 0) {
debug("channel %d: mux_rcb failed", c->self);
chan_mark_dead(ssh, c);
return;
}
}
static void
channel_post_mux_client_write(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
ssize_t len;
int r;
if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) ||
sshbuf_len(c->output) == 0)
return;
len = write(c->wfd, sshbuf_ptr(c->output), sshbuf_len(c->output));
if (len == -1 && (errno == EINTR || errno == EAGAIN))
return;
if (len <= 0) {
chan_mark_dead(ssh, c);
return;
}
if ((r = sshbuf_consume(c->output, len)) != 0)
fatal("%s: channel %d: consume: %s", __func__,
c->self, ssh_err(r));
}
static void
channel_post_mux_client(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
channel_post_mux_client_read(ssh, c, readset, writeset);
channel_post_mux_client_write(ssh, c, readset, writeset);
}
static void
channel_post_mux_listener(struct ssh *ssh, Channel *c,
fd_set *readset, fd_set *writeset)
{
Channel *nc;
struct sockaddr_storage addr;
socklen_t addrlen;
int newsock;
uid_t euid;
gid_t egid;
if (!FD_ISSET(c->sock, readset))
return;
debug("multiplexing control connection");
/*
* Accept connection on control socket
*/
memset(&addr, 0, sizeof(addr));
addrlen = sizeof(addr);
if ((newsock = accept(c->sock, (struct sockaddr*)&addr,
&addrlen)) == -1) {
error("%s accept: %s", __func__, strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
if (getpeereid(newsock, &euid, &egid) == -1) {
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(ssh, "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(ssh, nc);
/* mux state transitions must not elicit protocol messages */
nc->flags |= CHAN_LOCAL;
}
static void
channel_handler_init(struct ssh_channels *sc)
{
chan_fn **pre, **post;
if ((pre = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*pre))) == NULL ||
(post = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*post))) == NULL)
fatal("%s: allocation failed", __func__);
pre[SSH_CHANNEL_OPEN] = &channel_pre_open;
pre[SSH_CHANNEL_X11_OPEN] = &channel_pre_x11_open;
pre[SSH_CHANNEL_PORT_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_RPORT_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_UNIX_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_RUNIX_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_X11_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_AUTH_SOCKET] = &channel_pre_listener;
pre[SSH_CHANNEL_CONNECTING] = &channel_pre_connecting;
pre[SSH_CHANNEL_DYNAMIC] = &channel_pre_dynamic;
pre[SSH_CHANNEL_RDYNAMIC_FINISH] = &channel_pre_connecting;
pre[SSH_CHANNEL_MUX_LISTENER] = &channel_pre_listener;
pre[SSH_CHANNEL_MUX_CLIENT] = &channel_pre_mux_client;
post[SSH_CHANNEL_OPEN] = &channel_post_open;
post[SSH_CHANNEL_PORT_LISTENER] = &channel_post_port_listener;
post[SSH_CHANNEL_RPORT_LISTENER] = &channel_post_port_listener;
post[SSH_CHANNEL_UNIX_LISTENER] = &channel_post_port_listener;
post[SSH_CHANNEL_RUNIX_LISTENER] = &channel_post_port_listener;
post[SSH_CHANNEL_X11_LISTENER] = &channel_post_x11_listener;
post[SSH_CHANNEL_AUTH_SOCKET] = &channel_post_auth_listener;
post[SSH_CHANNEL_CONNECTING] = &channel_post_connecting;
post[SSH_CHANNEL_DYNAMIC] = &channel_post_open;
post[SSH_CHANNEL_RDYNAMIC_FINISH] = &channel_post_connecting;
post[SSH_CHANNEL_MUX_LISTENER] = &channel_post_mux_listener;
post[SSH_CHANNEL_MUX_CLIENT] = &channel_post_mux_client;
sc->channel_pre = pre;
sc->channel_post = post;
}
/* gc dead channels */
static void
channel_garbage_collect(struct ssh *ssh, Channel *c)
{
if (c == NULL)
return;
if (c->detach_user != NULL) {
if (!chan_is_dead(ssh, c, c->detach_close))
return;
debug2("channel %d: gc: notify user", c->self);
c->detach_user(ssh, 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(ssh, c, 1))
return;
debug2("channel %d: garbage collecting", c->self);
channel_free(ssh, c);
}
enum channel_table { CHAN_PRE, CHAN_POST };
static void
channel_handler(struct ssh *ssh, int table,
fd_set *readset, fd_set *writeset, time_t *unpause_secs)
{
struct ssh_channels *sc = ssh->chanctxt;
chan_fn **ftab = table == CHAN_PRE ? sc->channel_pre : sc->channel_post;
u_int i, oalloc;
Channel *c;
time_t now;
now = monotime();
if (unpause_secs != NULL)
*unpause_secs = 0;
for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) {
c = sc->channels[i];
if (c == NULL)
continue;
if (c->delayed) {
if (table == CHAN_PRE)
c->delayed = 0;
else
continue;
}
if (ftab[c->type] != NULL) {
/*
* Run handlers that are not paused.
*/
if (c->notbefore <= now)
(*ftab[c->type])(ssh, 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(ssh, c);
}
if (unpause_secs != NULL && *unpause_secs != 0)
debug3("%s: first channel unpauses in %d seconds",
__func__, (int)*unpause_secs);
}
/*
* Create sockets before allocating the select bitmasks.
* This is necessary for things that need to happen after reading
* the network-input but before channel_prepare_select().
*/
static void
channel_before_prepare_select(struct ssh *ssh)
{
struct ssh_channels *sc = ssh->chanctxt;
Channel *c;
u_int i, oalloc;
for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) {
c = sc->channels[i];
if (c == NULL)
continue;
if (c->type == SSH_CHANNEL_RDYNAMIC_OPEN)
channel_before_prepare_select_rdynamic(ssh, c);
}
}
/*
* Allocate/update select bitmasks and add any bits relevant to channels in
* select bitmasks.
*/
void
channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
int *maxfdp, u_int *nallocp, time_t *minwait_secs)
{
u_int n, sz, nfdset;
channel_before_prepare_select(ssh); /* might update channel_max_fd */
n = MAXIMUM(*maxfdp, ssh->chanctxt->channel_max_fd);
nfdset = howmany(n+1, NFDBITS);
/* Explicitly test here, because xrealloc isn't always called */
if (nfdset && SIZE_MAX / nfdset < sizeof(fd_mask))
fatal("channel_prepare_select: max_fd (%d) is too large", n);
sz = nfdset * sizeof(fd_mask);
/* perhaps check sz < nalloc/2 and shrink? */
if (*readsetp == NULL || sz > *nallocp) {
*readsetp = xreallocarray(*readsetp, nfdset, sizeof(fd_mask));
*writesetp = xreallocarray(*writesetp, nfdset, sizeof(fd_mask));
*nallocp = sz;
}
*maxfdp = n;
memset(*readsetp, 0, sz);
memset(*writesetp, 0, sz);
if (!ssh_packet_is_rekeying(ssh))
channel_handler(ssh, CHAN_PRE, *readsetp, *writesetp,
minwait_secs);
}
/*
* After select, perform any appropriate operations for channels which have
* events pending.
*/
void
channel_after_select(struct ssh *ssh, fd_set *readset, fd_set *writeset)
{
channel_handler(ssh, CHAN_POST, readset, writeset, NULL);
}
/*
* Enqueue data for channels with open or draining c->input.
*/
static void
channel_output_poll_input_open(struct ssh *ssh, Channel *c)
{
size_t len, plen;
const u_char *pkt;
int r;
if ((len = sshbuf_len(c->input)) == 0) {
if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
/*
* input-buffer is empty and read-socket shutdown:
* tell peer, that we will not send more data:
* send IEOF.
* hack for extended data: delay EOF if EFD still
* in use.
*/
if (CHANNEL_EFD_INPUT_ACTIVE(c))
debug2("channel %d: "
"ibuf_empty delayed efd %d/(%zu)",
c->self, c->efd, sshbuf_len(c->extended));
else
chan_ibuf_empty(ssh, c);
}
return;
}
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
if (c->datagram) {
/* Check datagram will fit; drop if not */
if ((r = sshbuf_get_string_direct(c->input, &pkt, &plen)) != 0)
fatal("%s: channel %d: get datagram: %s", __func__,
c->self, ssh_err(r));
/*
* XXX this does tail-drop on the datagram queue which is
* usually suboptimal compared to head-drop. Better to have
* backpressure at read time? (i.e. read + discard)
*/
if (plen > c->remote_window || plen > c->remote_maxpacket) {
debug("channel %d: datagram too big", c->self);
return;
}
/* Enqueue it */
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_string(ssh, pkt, plen)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: datagram: %s", __func__,
c->self, ssh_err(r));
}
c->remote_window -= plen;
return;
}
/* Enqueue packet for buffered data. */
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
if (len == 0)
return;
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_string(ssh, sshbuf_ptr(c->input), len)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: data: %s", __func__,
c->self, ssh_err(r));
}
if ((r = sshbuf_consume(c->input, len)) != 0)
fatal("%s: channel %i: consume: %s", __func__,
c->self, ssh_err(r));
c->remote_window -= len;
}
/*
* Enqueue data for channels with open c->extended in read mode.
*/
static void
channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
{
size_t len;
int r;
if ((len = sshbuf_len(c->extended)) == 0)
return;
debug2("channel %d: rwin %u elen %zu euse %d", c->self,
c->remote_window, sshbuf_len(c->extended), c->extended_usage);
if (len > c->remote_window)
len = c->remote_window;
if (len > c->remote_maxpacket)
len = c->remote_maxpacket;
if (len == 0)
return;
if (!c->have_remote_id)
fatal(":%s: channel %d: no remote id", __func__, c->self);
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, SSH2_EXTENDED_DATA_STDERR)) != 0 ||
(r = sshpkt_put_string(ssh, sshbuf_ptr(c->extended), len)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
fatal("%s: channel %i: data: %s", __func__,
c->self, ssh_err(r));
}
if ((r = sshbuf_consume(c->extended, len)) != 0)
fatal("%s: channel %i: consume: %s", __func__,
c->self, ssh_err(r));
c->remote_window -= len;
debug2("channel %d: sent ext data %zu", c->self, len);
}
/* If there is data to send to the connection, enqueue some of it now. */
void
channel_output_poll(struct ssh *ssh)
{
struct ssh_channels *sc = ssh->chanctxt;
Channel *c;
u_int i;
for (i = 0; i < sc->channels_alloc; i++) {
c = sc->channels[i];
if (c == NULL)
continue;
/*
* We are only interested in channels that can have buffered
* incoming data.
*/
if (c->type != SSH_CHANNEL_OPEN)
continue;
if ((c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
/* XXX is this true? */
debug3("channel %d: will not send data after close",
c->self);
continue;
}
/* Get the amount of buffered data for this channel. */
if (c->istate == CHAN_INPUT_OPEN ||
c->istate == CHAN_INPUT_WAIT_DRAIN)
channel_output_poll_input_open(ssh, c);
/* Send extended data, i.e. stderr */
if (!(c->flags & CHAN_EOF_SENT) &&
c->extended_usage == CHAN_EXTENDED_READ)
channel_output_poll_extended_read(ssh, c);
}
}
/* -- mux proxy support */
/*
* When multiplexing channel messages for mux clients we have to deal
* with downstream messages from the mux client and upstream messages
* from the ssh server:
* 1) Handling downstream messages is straightforward and happens
* in channel_proxy_downstream():
* - We forward all messages (mostly) unmodified to the server.
* - However, in order to route messages from upstream to the correct
* downstream client, we have to replace the channel IDs used by the
* mux clients with a unique channel ID because the mux clients might
* use conflicting channel IDs.
* - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and
* SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local
* SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID
* with the newly allocated channel ID.
* 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY
* channels and processed by channel_proxy_upstream(). The local channel ID
* is then translated back to the original mux client ID.
* 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE
* messages so we can clean up SSH_CHANNEL_MUX_PROXY channels.
* 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the
* downstream mux client are removed.
* 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server
* requires more work, because they are not addressed to a specific
* channel. E.g. client_request_forwarded_tcpip() needs to figure
* out whether the request is addressed to the local client or a
* specific downstream client based on the listen-address/port.
* 6) Agent and X11-Forwarding have a similar problem and are currently
* not supported as the matching session/channel cannot be identified
* easily.
*/
/*
* receive packets from downstream mux clients:
* channel callback fired on read from mux client, creates
* SSH_CHANNEL_MUX_PROXY channels and translates channel IDs
* on channel creation.
*/
int
channel_proxy_downstream(struct ssh *ssh, Channel *downstream)
{
Channel *c = NULL;
struct sshbuf *original = NULL, *modified = NULL;
const u_char *cp;
char *ctype = NULL, *listen_host = NULL;
u_char type;
size_t have;
int ret = -1, r;
u_int id, remote_id, listen_port;
/* sshbuf_dump(downstream->input, stderr); */
if ((r = sshbuf_get_string_direct(downstream->input, &cp, &have))
!= 0) {
error("%s: malformed message: %s", __func__, ssh_err(r));
return -1;
}
if (have < 2) {
error("%s: short message", __func__);
return -1;
}
type = cp[1];
/* skip padlen + type */
cp += 2;
have -= 2;
if (ssh_packet_log_type(type))
debug3("%s: channel %u: down->up: type %u", __func__,
downstream->self, type);
switch (type) {
case SSH2_MSG_CHANNEL_OPEN:
if ((original = sshbuf_from(cp, have)) == NULL ||
(modified = sshbuf_new()) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 ||
(r = sshbuf_get_u32(original, &id)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
-1, -1, -1, 0, 0, 0, ctype, 1);
c->mux_ctx = downstream; /* point to mux client */
c->mux_downstream_id = id; /* original downstream id */
if ((r = sshbuf_put_cstring(modified, ctype)) != 0 ||
(r = sshbuf_put_u32(modified, c->self)) != 0 ||
(r = sshbuf_putb(modified, original)) != 0) {
error("%s: compose error %s", __func__, ssh_err(r));
channel_free(ssh, c);
goto out;
}
break;
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
/*
* Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we
* need to parse 'remote_id' instead of 'ctype'.
*/
if ((original = sshbuf_from(cp, have)) == NULL ||
(modified = sshbuf_new()) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_u32(original, &remote_id)) != 0 ||
(r = sshbuf_get_u32(original, &id)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
-1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
c->mux_ctx = downstream; /* point to mux client */
c->mux_downstream_id = id;
c->remote_id = remote_id;
c->have_remote_id = 1;
if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
(r = sshbuf_put_u32(modified, c->self)) != 0 ||
(r = sshbuf_putb(modified, original)) != 0) {
error("%s: compose error %s", __func__, ssh_err(r));
channel_free(ssh, c);
goto out;
}
break;
case SSH2_MSG_GLOBAL_REQUEST:
if ((original = sshbuf_from(cp, have)) == NULL) {
error("%s: alloc", __func__);
goto out;
}
if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
if (strcmp(ctype, "tcpip-forward") != 0) {
error("%s: unsupported request %s", __func__, ctype);
goto out;
}
if ((r = sshbuf_get_u8(original, NULL)) != 0 ||
(r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 ||
(r = sshbuf_get_u32(original, &listen_port)) != 0) {
error("%s: parse error %s", __func__, ssh_err(r));
goto out;
}
if (listen_port > 65535) {
error("%s: tcpip-forward for %s: bad port %u",
__func__, listen_host, listen_port);
goto out;
}
/* Record that connection to this host/port is permitted. */
permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, "<mux>", -1,
listen_host, NULL, (int)listen_port, downstream);
listen_host = NULL;
break;
case SSH2_MSG_CHANNEL_CLOSE:
if (have < 4)
break;
remote_id = PEEK_U32(cp);
if ((c = channel_by_remote_id(ssh, remote_id)) != NULL) {
if (c->flags & CHAN_CLOSE_RCVD)
channel_free(ssh, c);
else
c->flags |= CHAN_CLOSE_SENT;
}
break;
}
if (modified) {
if ((r = sshpkt_start(ssh, type)) != 0 ||
(r = sshpkt_putb(ssh, modified)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
error("%s: send %s", __func__, ssh_err(r));
goto out;
}
} else {
if ((r = sshpkt_start(ssh, type)) != 0 ||
(r = sshpkt_put(ssh, cp, have)) != 0 ||
(r = sshpkt_send(ssh)) != 0) {
error("%s: send %s", __func__, ssh_err(r));
goto out;
}
}
ret = 0;
out:
free(ctype);
free(listen_host);
sshbuf_free(original);
sshbuf_free(modified);
return ret;
}
/*
* receive packets from upstream server and de-multiplex packets
* to correct downstream:
* implemented as a helper for channel input handlers,
* replaces local (proxy) channel ID with downstream channel ID.
*/
int
channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
{
struct sshbuf *b = NULL;
Channel *downstream;
const u_char *cp = NULL;
size_t len;
int r;
/*
* When receiving packets from the peer we need to check whether we
* need to forward the packets to the mux client. In this case we
* restore the original channel id and keep track of CLOSE messages,
* so we can cleanup the channel.
*/
if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY)
return 0;
if ((downstream = c->mux_ctx) == NULL)
return 0;
switch (type) {
case SSH2_MSG_CHANNEL_CLOSE:
case SSH2_MSG_CHANNEL_DATA:
case SSH2_MSG_CHANNEL_EOF:
case SSH2_MSG_CHANNEL_EXTENDED_DATA:
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
case SSH2_MSG_CHANNEL_OPEN_FAILURE:
case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
case SSH2_MSG_CHANNEL_SUCCESS:
case SSH2_MSG_CHANNEL_FAILURE:
case SSH2_MSG_CHANNEL_REQUEST:
break;
default:
debug2("%s: channel %u: unsupported type %u", __func__,
c->self, type);
return 0;
}
if ((b = sshbuf_new()) == NULL) {
error("%s: alloc reply", __func__);
goto out;
}
/* get remaining payload (after id) */
cp = sshpkt_ptr(ssh, &len);
if (cp == NULL) {
error("%s: no packet", __func__);
goto out;
}
/* translate id and send to muxclient */
if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */
(r = sshbuf_put_u8(b, type)) != 0 ||
(r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
(r = sshbuf_put(b, cp, len)) != 0 ||
(r = sshbuf_put_stringb(downstream->output, b)) != 0) {
error("%s: compose for muxclient %s", __func__, ssh_err(r));
goto out;
}
/* sshbuf_dump(b, stderr); */
if (ssh_packet_log_type(type))
debug3("%s: channel %u: up->down: type %u", __func__, c->self,
type);
out:
/* update state */
switch (type) {
case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
/* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
if (cp && len > 4) {
c->remote_id = PEEK_U32(cp);
c->have_remote_id = 1;
}
break;
case SSH2_MSG_CHANNEL_CLOSE:
if (c->flags & CHAN_CLOSE_SENT)
channel_free(ssh, c);
else
c->flags |= CHAN_CLOSE_RCVD;
break;
}
sshbuf_free(b);
return 1;
}
/* -- protocol input */
/* Parse a channel ID from the current packet */
static int
channel_parse_id(struct ssh *ssh, const char *where, const char *what)
{
u_int32_t id;
int r;
if ((r = sshpkt_get_u32(ssh, &id)) != 0) {
error("%s: parse id: %s", where, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid %s message", what);
}
if (id > INT_MAX) {
error("%s: bad channel id %u: %s", where, id, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid %s channel id", what);
}
return (int)id;
}
/* Lookup a channel from an ID in the current packet */
static Channel *
channel_from_packet_id(struct ssh *ssh, const char *where, const char *what)
{
int id = channel_parse_id(ssh, where, what);
Channel *c;
if ((c = channel_lookup(ssh, id)) == NULL) {
ssh_packet_disconnect(ssh,
"%s packet referred to nonexistent channel %d", what, id);
}
return c;
}
int
channel_input_data(int type, u_int32_t seq, struct ssh *ssh)
{
const u_char *data;
size_t data_len, win_len;
Channel *c = channel_from_packet_id(ssh, __func__, "data");
int r;
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
/* Ignore any data for non-open channels (might happen on close) */
if (c->type != SSH_CHANNEL_OPEN &&
c->type != SSH_CHANNEL_RDYNAMIC_OPEN &&
c->type != SSH_CHANNEL_RDYNAMIC_FINISH &&
c->type != SSH_CHANNEL_X11_OPEN)
return 0;
/* Get the data. */
if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0)
fatal("%s: channel %d: get data: %s", __func__,
c->self, ssh_err(r));
win_len = data_len;
if (c->datagram)
win_len += 4; /* string length header */
/*
* The sending side reduces its window as it sends data, so we
* must 'fake' consumption of the data in order to ensure that window
* updates are sent back. Otherwise the connection might deadlock.
*/
if (c->ostate != CHAN_OUTPUT_OPEN) {
c->local_window -= win_len;
c->local_consumed += win_len;
return 0;
}
if (win_len > c->local_maxpacket) {
logit("channel %d: rcvd big packet %zu, maxpack %u",
c->self, win_len, c->local_maxpacket);
return 0;
}
if (win_len > c->local_window) {
logit("channel %d: rcvd too much data %zu, win %u",
c->self, win_len, c->local_window);
return 0;
}
c->local_window -= win_len;
if (c->datagram) {
if ((r = sshbuf_put_string(c->output, data, data_len)) != 0)
fatal("%s: channel %d: append datagram: %s",
__func__, c->self, ssh_err(r));
} else if ((r = sshbuf_put(c->output, data, data_len)) != 0)
fatal("%s: channel %d: append data: %s",
__func__, c->self, ssh_err(r));
return 0;
}
int
channel_input_extended_data(int type, u_int32_t seq, struct ssh *ssh)
{
const u_char *data;
size_t data_len;
u_int32_t tcode;
Channel *c = channel_from_packet_id(ssh, __func__, "extended data");
int r;
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if (c->type != SSH_CHANNEL_OPEN) {
logit("channel %d: ext data for non open", c->self);
return 0;
}
if (c->flags & CHAN_EOF_RCVD) {
if (datafellows & SSH_BUG_EXTEOF)
debug("channel %d: accepting ext data after eof",
c->self);
else
ssh_packet_disconnect(ssh, "Received extended_data "
"after EOF on channel %d.", c->self);
}
if ((r = sshpkt_get_u32(ssh, &tcode)) != 0) {
error("%s: parse tcode: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid extended_data message");
}
if (c->efd == -1 ||
c->extended_usage != CHAN_EXTENDED_WRITE ||
tcode != SSH2_EXTENDED_DATA_STDERR) {
logit("channel %d: bad ext data", c->self);
return 0;
}
if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
error("%s: parse data: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid extended_data message");
}
if (data_len > c->local_window) {
logit("channel %d: rcvd too much extended_data %zu, win %u",
c->self, data_len, c->local_window);
return 0;
}
debug2("channel %d: rcvd ext data %zu", c->self, data_len);
/* XXX sshpkt_getb? */
if ((r = sshbuf_put(c->extended, data, data_len)) != 0)
error("%s: append: %s", __func__, ssh_err(r));
c->local_window -= data_len;
return 0;
}
int
channel_input_ieof(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = channel_from_packet_id(ssh, __func__, "ieof");
int r;
if ((r = sshpkt_get_end(ssh)) != 0) {
error("%s: parse data: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid ieof message");
}
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
chan_rcvd_ieof(ssh, 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 (sshbuf_len(c->input) == 0)
chan_ibuf_empty(ssh, c);
}
return 0;
}
int
channel_input_oclose(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = channel_from_packet_id(ssh, __func__, "oclose");
int r;
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if ((r = sshpkt_get_end(ssh)) != 0) {
error("%s: parse data: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid oclose message");
}
chan_rcvd_oclose(ssh, c);
return 0;
}
int
channel_input_open_confirmation(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation");
u_int32_t remote_window, remote_maxpacket;
int r;
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if (c->type != SSH_CHANNEL_OPENING)
ssh_packet_disconnect(ssh, "Received open confirmation for "
"non-opening channel %d.", c->self);
/*
* Record the remote channel number and mark that the channel
* is now open.
*/
if ((r = sshpkt_get_u32(ssh, &c->remote_id)) != 0 ||
(r = sshpkt_get_u32(ssh, &remote_window)) != 0 ||
(r = sshpkt_get_u32(ssh, &remote_maxpacket)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
error("%s: window/maxpacket: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid open confirmation message");
}
c->have_remote_id = 1;
c->remote_window = remote_window;
c->remote_maxpacket = remote_maxpacket;
c->type = SSH_CHANNEL_OPEN;
if (c->open_confirm) {
debug2("%s: channel %d: callback start", __func__, c->self);
c->open_confirm(ssh, c->self, 1, c->open_confirm_ctx);
debug2("%s: channel %d: callback done", __func__, c->self);
}
debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
c->remote_window, c->remote_maxpacket);
return 0;
}
static char *
reason2txt(int reason)
{
switch (reason) {
case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
return "administratively prohibited";
case SSH2_OPEN_CONNECT_FAILED:
return "connect failed";
case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
return "unknown channel type";
case SSH2_OPEN_RESOURCE_SHORTAGE:
return "resource shortage";
}
return "unknown reason";
}
int
channel_input_open_failure(int type, u_int32_t seq, struct ssh *ssh)
{
Channel *c = channel_from_packet_id(ssh, __func__, "open failure");
u_int32_t reason;
char *msg = NULL;
int r;
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if (c->type != SSH_CHANNEL_OPENING)
ssh_packet_disconnect(ssh, "Received open failure for "
"non-opening channel %d.", c->self);
if ((r = sshpkt_get_u32(ssh, &reason)) != 0) {
error("%s: reason: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid open failure message");
}
/* skip language */
if ((r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
(r = sshpkt_get_string_direct(ssh, NULL, NULL)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
error("%s: message/lang: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid open failure message");
}
logit("channel %d: open failed: %s%s%s", c->self,
reason2txt(reason), msg ? ": ": "", msg ? msg : "");
free(msg);
if (c->open_confirm) {
debug2("%s: channel %d: callback start", __func__, c->self);
c->open_confirm(ssh, c->self, 0, c->open_confirm_ctx);
debug2("%s: channel %d: callback done", __func__, c->self);
}
/* Schedule the channel for cleanup/deletion. */
chan_mark_dead(ssh, c);
return 0;
}
int
channel_input_window_adjust(int type, u_int32_t seq, struct ssh *ssh)
{
int id = channel_parse_id(ssh, __func__, "window adjust");
Channel *c;
u_int32_t adjust;
u_int new_rwin;
int r;
if ((c = channel_lookup(ssh, id)) == NULL) {
logit("Received window adjust for non-open channel %d.", id);
return 0;
}
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if ((r = sshpkt_get_u32(ssh, &adjust)) != 0 ||
(r = sshpkt_get_end(ssh)) != 0) {
error("%s: adjust: %s", __func__, ssh_err(r));
ssh_packet_disconnect(ssh, "Invalid window adjust message");
}
debug2("channel %d: rcvd adjust %u", c->self, adjust);
if ((new_rwin = c->remote_window + adjust) < c->remote_window) {
fatal("channel %d: adjust %u overflows remote window %u",
c->self, adjust, c->remote_window);
}
c->remote_window = new_rwin;
return 0;
}
int
channel_input_status_confirm(int type, u_int32_t seq, struct ssh *ssh)
{
int id = channel_parse_id(ssh, __func__, "status confirm");
Channel *c;
struct channel_confirm *cc;
/* Reset keepalive timeout */
ssh_packet_set_alive_timeouts(ssh, 0);
debug2("%s: type %d id %d", __func__, type, id);
if ((c = channel_lookup(ssh, id)) == NULL) {
logit("%s: %d: unknown", __func__, id);
return 0;
}
if (channel_proxy_upstream(c, type, seq, ssh))
return 0;
if (sshpkt_get_end(ssh) != 0)
ssh_packet_disconnect(ssh, "Invalid status confirm message");
if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
return 0;
cc->cb(ssh, type, c, cc->ctx);
TAILQ_REMOVE(&c->status_confirms, cc, entry);
freezero(cc, sizeof(*cc));
return 0;
}
/* -- tcp forwarding */
void
channel_set_af(struct ssh *ssh, int af)
{
ssh->chanctxt->IPv4or6 = af;
}
/*
* Determine whether or not a port forward listens to loopback, the
* specified address or wildcard. On the client, a specified bind
* address will always override gateway_ports. On the server, a
* gateway_ports of 1 (``yes'') will override the client's specification
* and force a wildcard bind, whereas a value of 2 (``clientspecified'')
* will bind to whatever address the client asked for.
*
* Special-case listen_addrs are:
*
* "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
* "" (empty string), "*" -> wildcard v4/v6
* "localhost" -> loopback v4/v6
* "127.0.0.1" / "::1" -> accepted even if gateway_ports isn't set
*/
static const char *
channel_fwd_bind_addr(struct ssh *ssh, const char *listen_addr, int *wildcardp,
int is_client, struct ForwardOptions *fwd_opts)
{
const char *addr = NULL;
int wildcard = 0;
if (listen_addr == NULL) {
/* No address specified: default to gateway_ports setting */
if (fwd_opts->gateway_ports)
wildcard = 1;
} else if (fwd_opts->gateway_ports || is_client) {
if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) ||
*listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
(!is_client && fwd_opts->gateway_ports == 1)) {
wildcard = 1;
/*
* Notify client if they requested a specific listen
* address and it was overridden.
*/
if (*listen_addr != '\0' &&
strcmp(listen_addr, "0.0.0.0") != 0 &&
strcmp(listen_addr, "*") != 0) {
ssh_packet_send_debug(ssh,
"Forwarding listen address "
"\"%s\" overridden by server "
"GatewayPorts", listen_addr);
}
} else if (strcmp(listen_addr, "localhost") != 0 ||
strcmp(listen_addr, "127.0.0.1") == 0 ||
strcmp(listen_addr, "::1") == 0) {
/*
* Accept explicit localhost address when
* GatewayPorts=yes. The "localhost" hostname is
* deliberately skipped here so it will listen on all
* available local address families.
*/
addr = listen_addr;
}
} else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
strcmp(listen_addr, "::1") == 0) {
/*
* If a specific IPv4/IPv6 localhost address has been
* requested then accept it even if gateway_ports is in
* effect. This allows the client to prefer IPv4 or IPv6.
*/
addr = listen_addr;
}
if (wildcardp != NULL)
*wildcardp = wildcard;
return addr;
}
static int
channel_setup_fwd_listener_tcpip(struct ssh *ssh, int type,
struct Forward *fwd, int *allocated_listen_port,
struct ForwardOptions *fwd_opts)
{
Channel *c;
int sock, r, success = 0, wildcard = 0, is_client;
struct addrinfo hints, *ai, *aitop;
const char *host, *addr;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
in_port_t *lport_p;
is_client = (type == SSH_CHANNEL_PORT_LISTENER);
if (is_client && fwd->connect_path != NULL) {
host = fwd->connect_path;
} else {
host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
fwd->listen_host : fwd->connect_host;
if (host == NULL) {
error("No forward host name.");
return 0;
}
if (strlen(host) >= NI_MAXHOST) {
error("Forward host name too long.");
return 0;
}
}
/* Determine the bind address, cf. channel_fwd_bind_addr() comment */
addr = channel_fwd_bind_addr(ssh, fwd->listen_host, &wildcard,
is_client, fwd_opts);
debug3("%s: type %d wildcard %d addr %s", __func__,
type, wildcard, (addr == NULL) ? "NULL" : addr);
/*
* getaddrinfo returns a loopback address if the hostname is
* set to NULL and hints.ai_flags is not AI_PASSIVE
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = ssh->chanctxt->IPv4or6;
hints.ai_flags = wildcard ? AI_PASSIVE : 0;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%d", fwd->listen_port);
if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
if (addr == NULL) {
/* This really shouldn't happen */
ssh_packet_disconnect(ssh, "getaddrinfo: fatal error: %s",
ssh_gai_strerror(r));
} else {
error("%s: getaddrinfo(%.64s): %s", __func__, addr,
ssh_gai_strerror(r));
}
return 0;
}
if (allocated_listen_port != NULL)
*allocated_listen_port = 0;
for (ai = aitop; ai; ai = ai->ai_next) {
switch (ai->ai_family) {
case AF_INET:
lport_p = &((struct sockaddr_in *)ai->ai_addr)->
sin_port;
break;
case AF_INET6:
lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
sin6_port;
break;
default:
continue;
}
/*
* If allocating a port for -R forwards, then use the
* same port for all address families.
*/
if (type == SSH_CHANNEL_RPORT_LISTENER &&
fwd->listen_port == 0 && allocated_listen_port != NULL &&
*allocated_listen_port > 0)
*lport_p = htons(*allocated_listen_port);
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("%s: getnameinfo failed", __func__);
continue;
}
/* Create a port to listen for the host. */
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock == -1) {
/* this is no error since kernel may not support ipv6 */
verbose("socket [%s]:%s: %.100s", ntop, strport,
strerror(errno));
continue;
}
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) == -1) {
/*
* address can be in if use ipv6 address is
* already bound
*/
if (!ai->ai_next)
error("bind [%s]:%s: %.100s",
ntop, strport, strerror(errno));
else
verbose("bind [%s]:%s: %.100s",
ntop, strport, strerror(errno));
close(sock);
continue;
}
/* Start listening for connections on the socket. */
if (listen(sock, SSH_LISTEN_BACKLOG) == -1) {
error("listen: %.100s", strerror(errno));
error("listen [%s]:%s: %.100s", ntop, strport,
strerror(errno));
close(sock);
continue;
}
/*
* fwd->listen_port == 0 requests a dynamically allocated port -
* record what we got.
*/
if (type == SSH_CHANNEL_RPORT_LISTENER &&
fwd->listen_port == 0 &&
allocated_listen_port != NULL &&
*allocated_listen_port == 0) {
*allocated_listen_port = get_local_port(sock);
debug("Allocated listen port %d",
*allocated_listen_port);
}
/* Allocate a channel number for the socket. */
c = channel_new(ssh, "port listener", type, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, "port listener", 1);
c->path = xstrdup(host);
c->host_port = fwd->connect_port;
c->listening_addr = addr == NULL ? NULL : xstrdup(addr);
if (fwd->listen_port == 0 && allocated_listen_port != NULL &&
!(datafellows & SSH_BUG_DYNAMIC_RPORT))
c->listening_port = *allocated_listen_port;
else
c->listening_port = fwd->listen_port;
success = 1;
}
if (success == 0)
error("%s: cannot listen to port: %d", __func__,
fwd->listen_port);
freeaddrinfo(aitop);
return success;
}
static int
channel_setup_fwd_listener_streamlocal(struct ssh *ssh, int type,
struct Forward *fwd, struct ForwardOptions *fwd_opts)
{
struct sockaddr_un sunaddr;
const char *path;
Channel *c;
int port, sock;
mode_t omask;
switch (type) {
case SSH_CHANNEL_UNIX_LISTENER:
if (fwd->connect_path != NULL) {
if (strlen(fwd->connect_path) > sizeof(sunaddr.sun_path)) {
error("Local connecting path too long: %s",
fwd->connect_path);
return 0;
}
path = fwd->connect_path;
port = PORT_STREAMLOCAL;
} else {
if (fwd->connect_host == NULL) {
error("No forward host name.");
return 0;
}
if (strlen(fwd->connect_host) >= NI_MAXHOST) {
error("Forward host name too long.");
return 0;
}
path = fwd->connect_host;
port = fwd->connect_port;
}
break;
case SSH_CHANNEL_RUNIX_LISTENER:
path = fwd->listen_path;
port = PORT_STREAMLOCAL;
break;
default:
error("%s: unexpected channel type %d", __func__, type);
return 0;
}
if (fwd->listen_path == NULL) {
error("No forward path name.");
return 0;
}
if (strlen(fwd->listen_path) > sizeof(sunaddr.sun_path)) {
error("Local listening path too long: %s", fwd->listen_path);
return 0;
}
debug3("%s: type %d path %s", __func__, type, fwd->listen_path);
/* Start a Unix domain listener. */
omask = umask(fwd_opts->streamlocal_bind_mask);
sock = unix_listener(fwd->listen_path, SSH_LISTEN_BACKLOG,
fwd_opts->streamlocal_bind_unlink);
umask(omask);
if (sock < 0)
return 0;
debug("Local forwarding listening on path %s.", fwd->listen_path);
/* Allocate a channel number for the socket. */
c = channel_new(ssh, "unix listener", type, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
0, "unix listener", 1);
c->path = xstrdup(path);
c->host_port = port;
c->listening_port = PORT_STREAMLOCAL;
c->listening_addr = xstrdup(fwd->listen_path);
return 1;
}
static int
channel_cancel_rport_listener_tcpip(struct ssh *ssh,
const char *host, u_short port)
{
u_int i;
int found = 0;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
Channel *c = ssh->chanctxt->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(ssh, c);
found = 1;
}
}
return found;
}
static int
channel_cancel_rport_listener_streamlocal(struct ssh *ssh, const char *path)
{
u_int i;
int found = 0;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
Channel *c = ssh->chanctxt->channels[i];
if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
continue;
if (c->path == NULL)
continue;
if (strcmp(c->path, path) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(ssh, c);
found = 1;
}
}
return found;
}
int
channel_cancel_rport_listener(struct ssh *ssh, struct Forward *fwd)
{
if (fwd->listen_path != NULL) {
return channel_cancel_rport_listener_streamlocal(ssh,
fwd->listen_path);
} else {
return channel_cancel_rport_listener_tcpip(ssh,
fwd->listen_host, fwd->listen_port);
}
}
static int
channel_cancel_lport_listener_tcpip(struct ssh *ssh,
const char *lhost, u_short lport, int cport,
struct ForwardOptions *fwd_opts)
{
u_int i;
int found = 0;
const char *addr = channel_fwd_bind_addr(ssh, lhost, NULL, 1, fwd_opts);
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
Channel *c = ssh->chanctxt->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(ssh, c);
found = 1;
}
}
return found;
}
static int
channel_cancel_lport_listener_streamlocal(struct ssh *ssh, const char *path)
{
u_int i;
int found = 0;
if (path == NULL) {
error("%s: no path specified.", __func__);
return 0;
}
for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
Channel *c = ssh->chanctxt->channels[i];
if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
continue;
if (c->listening_addr == NULL)
continue;
if (strcmp(c->listening_addr, path) == 0) {
debug2("%s: close channel %d", __func__, i);
channel_free(ssh, c);
found = 1;
}
}
return found;
}
int
channel_cancel_lport_listener(struct ssh *ssh,
struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
{
if (fwd->listen_path != NULL) {
return channel_cancel_lport_listener_streamlocal(ssh,
fwd->listen_path);
} else {
return channel_cancel_lport_listener_tcpip(ssh,
fwd->listen_host, fwd->listen_port, cport, fwd_opts);
}
}
/* protocol local port fwd, used by ssh */
int
channel_setup_local_fwd_listener(struct ssh *ssh,
struct Forward *fwd, struct ForwardOptions *fwd_opts)
{
if (fwd->listen_path != NULL) {
return channel_setup_fwd_listener_streamlocal(ssh,
SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
} else {
return channel_setup_fwd_listener_tcpip(ssh,
SSH_CHANNEL_PORT_LISTENER, fwd, NULL, fwd_opts);
}
}
/* Matches a remote forwarding permission against a requested forwarding */
static int
remote_open_match(struct permission *allowed_open, struct Forward *fwd)
{
int ret;
char *lhost;
/* XXX add ACLs for streamlocal */
if (fwd->listen_path != NULL)
return 1;
if (fwd->listen_host == NULL || allowed_open->listen_host == NULL)
return 0;
if (allowed_open->listen_port != FWD_PERMIT_ANY_PORT &&
allowed_open->listen_port != fwd->listen_port)
return 0;
/* Match hostnames case-insensitively */
lhost = xstrdup(fwd->listen_host);
lowercase(lhost);
ret = match_pattern(lhost, allowed_open->listen_host);
free(lhost);
return ret;
}
/* Checks whether a requested remote forwarding is permitted */
static int
check_rfwd_permission(struct ssh *ssh, struct Forward *fwd)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->remote_perms;
u_int i, permit, permit_adm = 1;
struct permission *perm;
/* XXX apply GatewayPorts override before checking? */
permit = pset->all_permitted;
if (!permit) {
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (remote_open_match(perm, fwd)) {
permit = 1;
break;
}
}
}
if (pset->num_permitted_admin > 0) {
permit_adm = 0;
for (i = 0; i < pset->num_permitted_admin; i++) {
perm = &pset->permitted_admin[i];
if (remote_open_match(perm, fwd)) {
permit_adm = 1;
break;
}
}
}
return permit && permit_adm;
}
/* protocol v2 remote port fwd, used by sshd */
int
channel_setup_remote_fwd_listener(struct ssh *ssh, struct Forward *fwd,
int *allocated_listen_port, struct ForwardOptions *fwd_opts)
{
if (!check_rfwd_permission(ssh, fwd)) {
ssh_packet_send_debug(ssh, "port forwarding refused");
if (fwd->listen_path != NULL)
/* XXX always allowed, see remote_open_match() */
logit("Received request from %.100s port %d to "
"remote forward to path \"%.100s\", "
"but the request was denied.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
fwd->listen_path);
else if(fwd->listen_host != NULL)
logit("Received request from %.100s port %d to "
"remote forward to host %.100s port %d, "
"but the request was denied.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
fwd->listen_host, fwd->listen_port );
else
logit("Received request from %.100s port %d to remote "
"forward, but the request was denied.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
return 0;
}
if (fwd->listen_path != NULL) {
return channel_setup_fwd_listener_streamlocal(ssh,
SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
} else {
return channel_setup_fwd_listener_tcpip(ssh,
SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
fwd_opts);
}
}
/*
* Translate the requested rfwd listen host to something usable for
* this server.
*/
static const char *
channel_rfwd_bind_host(const char *listen_host)
{
if (listen_host == NULL) {
return "localhost";
} else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
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_permission().
*/
int
channel_request_remote_forwarding(struct ssh *ssh, struct Forward *fwd)
{
int r, success = 0, idx = -1;
char *host_to_connect, *listen_host, *listen_path;
int port_to_connect, listen_port;
/* Send the forward request to the remote side. */
if (fwd->listen_path != NULL) {
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh,
"streamlocal-forward@openssh.com")) != 0 ||
(r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */
(r = sshpkt_put_cstring(ssh, fwd->listen_path)) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal("%s: request streamlocal: %s",
__func__, ssh_err(r));
} else {
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, "tcpip-forward")) != 0 ||
(r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */
(r = sshpkt_put_cstring(ssh,
channel_rfwd_bind_host(fwd->listen_host))) != 0 ||
(r = sshpkt_put_u32(ssh, fwd->listen_port)) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal("%s: request tcpip-forward: %s",
__func__, ssh_err(r));
}
/* Assume that server accepts the request */
success = 1;
if (success) {
/* Record that connection to this host/port is permitted. */
host_to_connect = listen_host = listen_path = NULL;
port_to_connect = listen_port = 0;
if (fwd->connect_path != NULL) {
host_to_connect = xstrdup(fwd->connect_path);
port_to_connect = PORT_STREAMLOCAL;
} else {
host_to_connect = xstrdup(fwd->connect_host);
port_to_connect = fwd->connect_port;
}
if (fwd->listen_path != NULL) {
listen_path = xstrdup(fwd->listen_path);
listen_port = PORT_STREAMLOCAL;
} else {
if (fwd->listen_host != NULL)
listen_host = xstrdup(fwd->listen_host);
listen_port = fwd->listen_port;
}
idx = permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL,
host_to_connect, port_to_connect,
listen_host, listen_path, listen_port, NULL);
}
return idx;
}
static int
open_match(struct permission *allowed_open, const char *requestedhost,
int requestedport)
{
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
allowed_open->port_to_connect != requestedport)
return 0;
if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 &&
strcmp(allowed_open->host_to_connect, requestedhost) != 0)
return 0;
return 1;
}
/*
* Note that in the listen host/port case
* we don't support FWD_PERMIT_ANY_PORT and
* need to translate between the configured-host (listen_host)
* and what we've sent to the remote server (channel_rfwd_bind_host)
*/
static int
open_listen_match_tcpip(struct permission *allowed_open,
const char *requestedhost, u_short requestedport, int translate)
{
const char *allowed_host;
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->listen_port != requestedport)
return 0;
if (!translate && allowed_open->listen_host == NULL &&
requestedhost == NULL)
return 1;
allowed_host = translate ?
channel_rfwd_bind_host(allowed_open->listen_host) :
allowed_open->listen_host;
if (allowed_host == NULL || requestedhost == NULL ||
strcmp(allowed_host, requestedhost) != 0)
return 0;
return 1;
}
static int
open_listen_match_streamlocal(struct permission *allowed_open,
const char *requestedpath)
{
if (allowed_open->host_to_connect == NULL)
return 0;
if (allowed_open->listen_port != PORT_STREAMLOCAL)
return 0;
if (allowed_open->listen_path == NULL ||
strcmp(allowed_open->listen_path, requestedpath) != 0)
return 0;
return 1;
}
/*
* Request cancellation of remote forwarding of connection host:port from
* local side.
*/
static int
channel_request_rforward_cancel_tcpip(struct ssh *ssh,
const char *host, u_short port)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
int r;
u_int i;
struct permission *perm = NULL;
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_listen_match_tcpip(perm, host, port, 0))
break;
perm = NULL;
}
if (perm == NULL) {
debug("%s: requested forward not found", __func__);
return -1;
}
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh, "cancel-tcpip-forward")) != 0 ||
(r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
(r = sshpkt_put_cstring(ssh, channel_rfwd_bind_host(host))) != 0 ||
(r = sshpkt_put_u32(ssh, port)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: send cancel: %s", __func__, ssh_err(r));
fwd_perm_clear(perm); /* unregister */
return 0;
}
/*
* Request cancellation of remote forwarding of Unix domain socket
* path from local side.
*/
static int
channel_request_rforward_cancel_streamlocal(struct ssh *ssh, const char *path)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
int r;
u_int i;
struct permission *perm = NULL;
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_listen_match_streamlocal(perm, path))
break;
perm = NULL;
}
if (perm == NULL) {
debug("%s: requested forward not found", __func__);
return -1;
}
if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
(r = sshpkt_put_cstring(ssh,
"cancel-streamlocal-forward@openssh.com")) != 0 ||
(r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
(r = sshpkt_put_cstring(ssh, path)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: send cancel: %s", __func__, ssh_err(r));
fwd_perm_clear(perm); /* unregister */
return 0;
}
/*
* Request cancellation of remote forwarding of a connection from local side.
*/
int
channel_request_rforward_cancel(struct ssh *ssh, struct Forward *fwd)
{
if (fwd->listen_path != NULL) {
return channel_request_rforward_cancel_streamlocal(ssh,
fwd->listen_path);
} else {
return channel_request_rforward_cancel_tcpip(ssh,
fwd->listen_host,
fwd->listen_port ? fwd->listen_port : fwd->allocated_port);
}
}
/*
* Permits opening to any host/port if permitted_user[] 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(struct ssh *ssh, int where)
{
struct permission_set *pset = permission_set_get(ssh, where);
if (pset->num_permitted_user == 0)
pset->all_permitted = 1;
}
/*
* Permit the specified host/port for forwarding.
*/
void
channel_add_permission(struct ssh *ssh, int who, int where,
char *host, int port)
{
int local = where == FORWARD_LOCAL;
struct permission_set *pset = permission_set_get(ssh, where);
debug("allow %s forwarding to host %s port %d",
fwd_ident(who, where), host, port);
/*
* Remote forwards set listen_host/port, local forwards set
* host/port_to_connect.
*/
permission_set_add(ssh, who, where,
local ? host : 0, local ? port : 0,
local ? NULL : host, NULL, local ? 0 : port, NULL);
pset->all_permitted = 0;
}
/*
* Administratively disable forwarding.
*/
void
channel_disable_admin(struct ssh *ssh, int where)
{
channel_clear_permission(ssh, FORWARD_ADM, where);
permission_set_add(ssh, FORWARD_ADM, where,
NULL, 0, NULL, NULL, 0, NULL);
}
/*
* Clear a list of permitted opens.
*/
void
channel_clear_permission(struct ssh *ssh, int who, int where)
{
struct permission **permp;
u_int *npermp;
permission_set_get_array(ssh, who, where, &permp, &npermp);
*permp = xrecallocarray(*permp, *npermp, 0, sizeof(**permp));
*npermp = 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_permission(struct ssh *ssh, int idx, int newport)
{
struct permission_set *pset = &ssh->chanctxt->local_perms;
if (idx < 0 || (u_int)idx >= pset->num_permitted_user) {
debug("%s: index out of range: %d num_permitted_user %d",
__func__, idx, pset->num_permitted_user);
return;
}
debug("%s allowed port %d for forwarding to host %s port %d",
newport > 0 ? "Updating" : "Removing",
newport,
pset->permitted_user[idx].host_to_connect,
pset->permitted_user[idx].port_to_connect);
if (newport <= 0)
fwd_perm_clear(&pset->permitted_user[idx]);
else {
pset->permitted_user[idx].listen_port =
(datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
}
}
/* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
int
permitopen_port(const char *p)
{
int port;
if (strcmp(p, "*") == 0)
return FWD_PERMIT_ANY_PORT;
if ((port = a2port(p)) > 0)
return port;
return -1;
}
/* Try to start non-blocking connect to next host in cctx list */
static int
connect_next(struct channel_connect *cctx)
{
int sock, saved_errno;
struct sockaddr_un *sunaddr;
char ntop[NI_MAXHOST];
char strport[MAXIMUM(NI_MAXSERV, sizeof(sunaddr->sun_path))];
for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
switch (cctx->ai->ai_family) {
case AF_UNIX:
/* unix:pathname instead of host:port */
sunaddr = (struct sockaddr_un *)cctx->ai->ai_addr;
strlcpy(ntop, "unix", sizeof(ntop));
strlcpy(strport, sunaddr->sun_path, sizeof(strport));
break;
case AF_INET:
case AF_INET6:
if (getnameinfo(cctx->ai->ai_addr, cctx->ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("connect_next: getnameinfo failed");
continue;
}
break;
default:
continue;
}
if ((sock = socket(cctx->ai->ai_family, cctx->ai->ai_socktype,
cctx->ai->ai_protocol)) == -1) {
if (cctx->ai->ai_next == NULL)
error("socket: %.100s", strerror(errno));
else
verbose("socket: %.100s", strerror(errno));
continue;
}
if (set_nonblock(sock) == -1)
fatal("%s: set_nonblock(%d)", __func__, sock);
if (connect(sock, cctx->ai->ai_addr,
cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) {
debug("connect_next: host %.100s ([%.100s]:%s): "
"%.100s", cctx->host, ntop, strport,
strerror(errno));
saved_errno = errno;
close(sock);
errno = saved_errno;
continue; /* fail -- try next */
}
if (cctx->ai->ai_family != AF_UNIX)
set_nodelay(sock);
debug("connect_next: host %.100s ([%.100s]:%s) "
"in progress, fd=%d", cctx->host, ntop, strport, sock);
cctx->ai = cctx->ai->ai_next;
return sock;
}
return -1;
}
static void
channel_connect_ctx_free(struct channel_connect *cctx)
{
free(cctx->host);
if (cctx->aitop) {
if (cctx->aitop->ai_family == AF_UNIX)
free(cctx->aitop);
else
freeaddrinfo(cctx->aitop);
}
memset(cctx, 0, sizeof(*cctx));
}
/*
* Return connecting socket to remote host:port or local socket path,
* passing back the failure reason if appropriate.
*/
static int
connect_to_helper(struct ssh *ssh, const char *name, int port, int socktype,
char *ctype, char *rname, struct channel_connect *cctx,
int *reason, const char **errmsg)
{
struct addrinfo hints;
int gaierr;
int sock = -1;
char strport[NI_MAXSERV];
if (port == PORT_STREAMLOCAL) {
struct sockaddr_un *sunaddr;
struct addrinfo *ai;
if (strlen(name) > sizeof(sunaddr->sun_path)) {
error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
return -1;
}
/*
* Fake up a struct addrinfo for AF_UNIX connections.
* channel_connect_ctx_free() must check ai_family
* and use free() not freeaddirinfo() for AF_UNIX.
*/
ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr));
memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr));
ai->ai_addr = (struct sockaddr *)(ai + 1);
ai->ai_addrlen = sizeof(*sunaddr);
ai->ai_family = AF_UNIX;
ai->ai_socktype = socktype;
ai->ai_protocol = PF_UNSPEC;
sunaddr = (struct sockaddr_un *)ai->ai_addr;
sunaddr->sun_family = AF_UNIX;
strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
cctx->aitop = ai;
} else {
memset(&hints, 0, sizeof(hints));
hints.ai_family = ssh->chanctxt->IPv4or6;
hints.ai_socktype = socktype;
snprintf(strport, sizeof strport, "%d", port);
if ((gaierr = getaddrinfo(name, strport, &hints, &cctx->aitop))
!= 0) {
if (errmsg != NULL)
*errmsg = ssh_gai_strerror(gaierr);
if (reason != NULL)
*reason = SSH2_OPEN_CONNECT_FAILED;
error("connect_to %.100s: unknown host (%s)", name,
ssh_gai_strerror(gaierr));
return -1;
}
}
cctx->host = xstrdup(name);
cctx->port = port;
cctx->ai = cctx->aitop;
if ((sock = connect_next(cctx)) == -1) {
error("connect to %.100s port %d failed: %s",
name, port, strerror(errno));
return -1;
}
return sock;
}
/* Return CONNECTING channel to remote host:port or local socket path */
static Channel *
connect_to(struct ssh *ssh, const char *host, int port,
char *ctype, char *rname)
{
struct channel_connect cctx;
Channel *c;
int sock;
memset(&cctx, 0, sizeof(cctx));
sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname,
&cctx, NULL, NULL);
if (sock == -1) {
channel_connect_ctx_free(&cctx);
return NULL;
}
c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
c->host_port = port;
c->path = xstrdup(host);
c->connect_ctx = cctx;
return c;
}
/*
* returns either the newly connected channel or the downstream channel
* that needs to deal with this connection.
*/
Channel *
channel_connect_by_listen_address(struct ssh *ssh, const char *listen_host,
u_short listen_port, char *ctype, char *rname)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
u_int i;
struct permission *perm;
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_listen_match_tcpip(perm,
listen_host, listen_port, 1)) {
if (perm->downstream)
return perm->downstream;
if (perm->port_to_connect == 0)
return rdynamic_connect_prepare(ssh,
ctype, rname);
return connect_to(ssh,
perm->host_to_connect, perm->port_to_connect,
ctype, rname);
}
}
error("WARNING: Server requests forwarding for unknown listen_port %d",
listen_port);
return NULL;
}
Channel *
channel_connect_by_listen_path(struct ssh *ssh, const char *path,
char *ctype, char *rname)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
u_int i;
struct permission *perm;
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_listen_match_streamlocal(perm, path)) {
return connect_to(ssh,
perm->host_to_connect, perm->port_to_connect,
ctype, rname);
}
}
error("WARNING: Server requests forwarding for unknown path %.100s",
path);
return NULL;
}
/* Check if connecting to that port is permitted and connect. */
Channel *
channel_connect_to_port(struct ssh *ssh, const char *host, u_short port,
char *ctype, char *rname, int *reason, const char **errmsg)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
struct channel_connect cctx;
Channel *c;
u_int i, permit, permit_adm = 1;
int sock;
struct permission *perm;
permit = pset->all_permitted;
if (!permit) {
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_match(perm, host, port)) {
permit = 1;
break;
}
}
}
if (pset->num_permitted_admin > 0) {
permit_adm = 0;
for (i = 0; i < pset->num_permitted_admin; i++) {
perm = &pset->permitted_admin[i];
if (open_match(perm, host, port)) {
permit_adm = 1;
break;
}
}
}
if (!permit || !permit_adm) {
logit("Received request from %.100s port %d to connect to "
"host %.100s port %d, but the request was denied.",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), host, port);
if (reason != NULL)
*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
return NULL;
}
memset(&cctx, 0, sizeof(cctx));
sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname,
&cctx, reason, errmsg);
if (sock == -1) {
channel_connect_ctx_free(&cctx);
return NULL;
}
c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
c->host_port = port;
c->path = xstrdup(host);
c->connect_ctx = cctx;
return c;
}
/* Check if connecting to that path is permitted and connect. */
Channel *
channel_connect_to_path(struct ssh *ssh, const char *path,
char *ctype, char *rname)
{
struct ssh_channels *sc = ssh->chanctxt;
struct permission_set *pset = &sc->local_perms;
u_int i, permit, permit_adm = 1;
struct permission *perm;
permit = pset->all_permitted;
if (!permit) {
for (i = 0; i < pset->num_permitted_user; i++) {
perm = &pset->permitted_user[i];
if (open_match(perm, path, PORT_STREAMLOCAL)) {
permit = 1;
break;
}
}
}
if (pset->num_permitted_admin > 0) {
permit_adm = 0;
for (i = 0; i < pset->num_permitted_admin; i++) {
perm = &pset->permitted_admin[i];
if (open_match(perm, path, PORT_STREAMLOCAL)) {
permit_adm = 1;
break;
}
}
}
if (!permit || !permit_adm) {
logit("Received request to connect to path %.100s, "
"but the request was denied.", path);
return NULL;
}
return connect_to(ssh, path, PORT_STREAMLOCAL, ctype, rname);
}
void
channel_send_window_changes(struct ssh *ssh)
{
struct ssh_channels *sc = ssh->chanctxt;
struct winsize ws;
int r;
u_int i;
for (i = 0; i < sc->channels_alloc; i++) {
if (sc->channels[i] == NULL || !sc->channels[i]->client_tty ||
sc->channels[i]->type != SSH_CHANNEL_OPEN)
continue;
if (ioctl(sc->channels[i]->rfd, TIOCGWINSZ, &ws) == -1)
continue;
channel_request_start(ssh, i, "window-change", 0);
if ((r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
(r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
fatal("%s: channel %u: send window-change: %s",
__func__, i, ssh_err(r));
}
}
/* Return RDYNAMIC_OPEN channel: channel allows SOCKS, but is not connected */
static Channel *
rdynamic_connect_prepare(struct ssh *ssh, char *ctype, char *rname)
{
Channel *c;
int r;
c = channel_new(ssh, ctype, SSH_CHANNEL_RDYNAMIC_OPEN, -1, -1, -1,
CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
c->host_port = 0;
c->path = NULL;
/*
* We need to open the channel before we have a FD,
* so that we can get SOCKS header from peer.
*/
if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
(r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
(r = sshpkt_put_u32(ssh, c->self)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
(r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) {
fatal("%s: channel %i: confirm: %s", __func__,
c->self, ssh_err(r));
}
return c;
}
/* Return CONNECTING socket to remote host:port or local socket path */
static int
rdynamic_connect_finish(struct ssh *ssh, Channel *c)
{
struct channel_connect cctx;
int sock;
memset(&cctx, 0, sizeof(cctx));
sock = connect_to_helper(ssh, c->path, c->host_port, SOCK_STREAM, NULL,
NULL, &cctx, NULL, NULL);
if (sock == -1)
channel_connect_ctx_free(&cctx);
else {
/* similar to SSH_CHANNEL_CONNECTING but we've already sent the open */
c->type = SSH_CHANNEL_RDYNAMIC_FINISH;
c->connect_ctx = cctx;
channel_register_fds(ssh, c, sock, sock, -1, 0, 1, 0);
}
return sock;
}
/* -- 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(struct ssh *ssh, 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 = ssh->chanctxt->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 == -1) {
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)
set_reuseaddr(sock);
if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
debug2("%s: bind port %d: %.100s", __func__,
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) == -1) {
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(ssh, "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 == -1)
error("socket: %.100s", strerror(errno));
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
return sock;
close(sock);
error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
return -1;
}
static int
connect_local_xsocket(u_int dnr)
{
char buf[1024];
snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
return connect_local_xsocket_path(buf);
}
#ifdef __APPLE__
static int
is_path_to_xsocket(const char *display, char *path, size_t pathlen)
{
struct stat sbuf;
if (strlcpy(path, display, pathlen) >= pathlen) {
error("%s: display path too long", __func__);
return 0;
}
if (display[0] != '/')
return 0;
if (stat(path, &sbuf) == 0) {
return 1;
} else {
char *dot = strrchr(path, '.');
if (dot != NULL) {
*dot = '\0';
if (stat(path, &sbuf) == 0) {
return 1;
}
}
}
return 0;
}
#endif
int
x11_connect_display(struct ssh *ssh)
{
u_int display_number;
const char *display;
char buf[1024], *cp;
struct addrinfo hints, *ai, *aitop;
char strport[NI_MAXSERV];
int gaierr, sock = 0;
/* Try to open a socket for the local X server. */
display = getenv("DISPLAY");
if (!display) {
error("DISPLAY not set.");
return -1;
}
/*
* Now we decode the value of the DISPLAY variable and make a
* connection to the real X server.
*/
#ifdef __APPLE__
/* Check if display is a path to a socket (as set by launchd). */
{
char path[PATH_MAX];
if (is_path_to_xsocket(display, path, sizeof(path))) {
debug("x11_connect_display: $DISPLAY is launchd");
/* Create a socket. */
sock = connect_local_xsocket_path(path);
if (sock < 0)
return -1;
/* OK, we now have a connection to the display. */
return sock;
}
}
#endif
/*
* Check if it is a unix domain socket. Unix domain displays are in
* one of the following formats: unix:d[.s], :d[.s], ::d[.s]
*/
if (strncmp(display, "unix:", 5) == 0 ||
display[0] == ':') {
/* Connect to the unix domain socket. */
if (sscanf(strrchr(display, ':') + 1, "%u",
&display_number) != 1) {
error("Could not parse display number from DISPLAY: "
"%.100s", display);
return -1;
}
/* Create a socket. */
sock = connect_local_xsocket(display_number);
if (sock < 0)
return -1;
/* OK, we now have a connection to the display. */
return sock;
}
/*
* Connect to an inet socket. The DISPLAY value is supposedly
* hostname:d[.s], where hostname may also be numeric IP address.
*/
strlcpy(buf, display, sizeof(buf));
cp = strchr(buf, ':');
if (!cp) {
error("Could not find ':' in DISPLAY: %.100s", display);
return -1;
}
*cp = 0;
/*
* buf now contains the host name. But first we parse the
* display number.
*/
if (sscanf(cp + 1, "%u", &display_number) != 1) {
error("Could not parse display number from DISPLAY: %.100s",
display);
return -1;
}
/* Look up the host address */
memset(&hints, 0, sizeof(hints));
hints.ai_family = ssh->chanctxt->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 == -1) {
debug2("socket: %.100s", strerror(errno));
continue;
}
/* Connect it to the display. */
if (connect(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
debug2("connect %.100s port %u: %.100s", buf,
6000 + display_number, strerror(errno));
close(sock);
continue;
}
/* Success */
break;
}
freeaddrinfo(aitop);
if (!ai) {
error("connect %.100s port %u: %.100s", buf,
6000 + display_number, strerror(errno));
return -1;
}
set_nodelay(sock);
return sock;
}
/*
* Requests forwarding of X11 connections, generates fake authentication
* data, and enables authentication spoofing.
* This should be called in the client only.
*/
void
x11_request_forwarding_with_spoofing(struct ssh *ssh, int client_session_id,
const char *disp, const char *proto, const char *data, int want_reply)
{
struct ssh_channels *sc = ssh->chanctxt;
u_int data_len = (u_int) strlen(data) / 2;
u_int i, value;
const char *cp;
char *new_data;
int r, screen_number;
if (sc->x11_saved_display == NULL)
sc->x11_saved_display = xstrdup(disp);
else if (strcmp(disp, sc->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 (sc->x11_saved_proto == NULL) {
/* Save protocol name. */
sc->x11_saved_proto = xstrdup(proto);
/* Extract real authentication data. */
sc->x11_saved_data = xmalloc(data_len);
for (i = 0; i < data_len; i++) {
if (sscanf(data + 2 * i, "%2x", &value) != 1)
fatal("x11_request_forwarding: bad "
"authentication data: %.100s", data);
sc->x11_saved_data[i] = value;
}
sc->x11_saved_data_len = data_len;
/* Generate fake data of the same length. */
sc->x11_fake_data = xmalloc(data_len);
arc4random_buf(sc->x11_fake_data, data_len);
sc->x11_fake_data_len = data_len;
}
/* Convert the fake data into hex. */
new_data = tohex(sc->x11_fake_data, data_len);
/* Send the request packet. */
channel_request_start(ssh, client_session_id, "x11-req", want_reply);
if ((r = sshpkt_put_u8(ssh, 0)) != 0 || /* bool: single connection */
(r = sshpkt_put_cstring(ssh, proto)) != 0 ||
(r = sshpkt_put_cstring(ssh, new_data)) != 0 ||
(r = sshpkt_put_u32(ssh, screen_number)) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal("%s: send x11-req: %s", __func__, ssh_err(r));
free(new_data);
}
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