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03e92dd27d
openssh/channels.c
Damien Miller 03e92dd27d use same close logic for stderr as stdout 
Avoids sending SIGPIPE to child processes after their parent exits
if they attempt to write to stderr.

Analysis and patch from JD Paul; patch reworked by Jakub Jelen and
myself. bz#2071; ok dtucker@
2019-02-08 14:50:36 +11:00

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/* $OpenBSD: channels.c,v 1.389 2019/01/19 21:37:13 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* This file contains functions for generic socket connection forwarding.
* There is also code for initiating connection forwarding for X11 connections,
* arbitrary tcp/ip connections, and the authentication agent connection.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
* SSH2 support added by Markus Friedl.
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
* Copyright (c) 1999 Dug Song. All rights reserved.
* Copyright (c) 1999 Theo de Raadt. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/un.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <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);
bzero(perm, 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);
}
}
/* Reutrns 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);
explicit_bzero(cc, sizeof(*cc));
free(cc);
}
if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
c->filter_cleanup(ssh, c->self, c->filter_ctx);
sc->channels[c->self] = NULL;
explicit_bzero(c, sizeof(*c));
free(c);
}
void
channel_free_all(struct ssh *ssh)
{
u_int i;
for (i = 0; i < ssh->chanctxt->channels_alloc; i++)
if (ssh->chanctxt->channels[i] != NULL)
channel_free(ssh, ssh->chanctxt->channels[i]);
}
/*
* 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 < 0) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
set_nodelay(newsock);
remote_ipaddr = get_peer_ipaddr(newsock);
remote_port = get_peer_port(newsock);
snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
remote_ipaddr, remote_port);
nc = channel_new(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 < 0) {
if (errno != EINTR && errno != EWOULDBLOCK &&
errno != ECONNABORTED)
error("accept: %.100s", strerror(errno));
if (errno == EMFILE || errno == ENFILE)
c->notbefore = monotime() + 1;
return;
}
if (c->host_port != PORT_STREAMLOCAL)
set_nodelay(newsock);
nc = channel_new(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 < 0) {
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) < 0) {
err = errno;
error("getsockopt SO_ERROR failed");
}
if (err == 0) {
debug("channel %d: connected to %s port %d",
c->self, c->connect_ctx.host, c->connect_ctx.port);
channel_connect_ctx_free(&c->connect_ctx);
c->type = SSH_CHANNEL_OPEN;
if (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 < 0 && (errno == EINTR ||
((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
return 1;
#ifndef PTY_ZEROREAD
if (len <= 0) {
#else
if ((!c->isatty && len <= 0) ||
(c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
#endif
debug2("channel %d: read<=0 rfd %d len %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 < 0 && (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 < 0 &&
(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 < 0 && (errno == EINTR || errno == EAGAIN ||
errno == EWOULDBLOCK))
return 1;
if (len <= 0) {
debug2("channel %d: closing write-efd %d", c->self, c->efd);
channel_close_fd(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 < 0 && (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 < 0 && (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 < 0 && (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) < 0) {
error("%s getpeereid failed: %s", __func__,
strerror(errno));
close(newsock);
return;
}
if ((euid != 0) && (getuid() != euid)) {
error("multiplex uid mismatch: peer euid %u != uid %u",
(u_int)euid, (u_int)getuid());
close(newsock);
return;
}
nc = channel_new(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;
int r;
/* 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 ((r = 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);
explicit_bzero(cc, sizeof(*cc));
free(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 localhost address when GatewayPorts=yes */
addr = listen_addr;
}
} else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
strcmp(listen_addr, "::1") == 0) {
/*
* If a specific IPv4/IPv6 localhost address has been
* requested then accept it even if gateway_ports is in
* effect. This allows the client to prefer IPv4 or IPv6.
*/
addr = listen_addr;
}
if (wildcardp != NULL)
*wildcardp = wildcard;
return addr;
}
static int
channel_setup_fwd_listener_tcpip(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 < 0) {
/* 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) < 0) {
/*
* 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) < 0) {
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");
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;
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;
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 to connect to host %.100s port %d, "
"but the request was denied.", 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) < 0)
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 < 0) {
if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
#ifdef EPFNOSUPPORT
&& (errno != EPFNOSUPPORT)
#endif
) {
error("socket: %.100s", strerror(errno));
freeaddrinfo(aitop);
return -1;
} else {
debug("x11_create_display_inet: Socket family %d not supported",
ai->ai_family);
continue;
}
}
if (ai->ai_family == AF_INET6)
sock_set_v6only(sock);
if (x11_use_localhost)
set_reuseaddr(sock);
if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
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) < 0) {
error("listen: %.100s", strerror(errno));
close(sock);
return -1;
}
}
/* Allocate a channel for each socket. */
*chanids = xcalloc(num_socks + 1, sizeof(**chanids));
for (n = 0; n < num_socks; n++) {
sock = socks[n];
nc = channel_new(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 < 0)
error("socket: %.100s", strerror(errno));
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
strlcpy(addr.sun_path, pathname, sizeof addr.sun_path);
if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
return sock;
close(sock);
error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
return -1;
}
static int
connect_local_xsocket(u_int dnr)
{
char buf[1024];
snprintf(buf, sizeof buf, _PATH_UNIX_X, dnr);
return connect_local_xsocket_path(buf);
}
#ifdef __APPLE__
static int
is_path_to_xsocket(const char *display, char *path, size_t pathlen)
{
struct stat sbuf;
if (strlcpy(path, display, pathlen) >= pathlen) {
error("%s: display path too long", __func__);
return 0;
}
if (display[0] != '/')
return 0;
if (stat(path, &sbuf) == 0) {
return 1;
} else {
char *dot = strrchr(path, '.');
if (dot != NULL) {
*dot = '\0';
if (stat(path, &sbuf) == 0) {
return 1;
}
}
}
return 0;
}
#endif
int
x11_connect_display(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 < 0) {
debug2("socket: %.100s", strerror(errno));
continue;
}
/* Connect it to the display. */
if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
debug2("connect %.100s port %u: %.100s", buf,
6000 + display_number, strerror(errno));
close(sock);
continue;
}
/* Success */
break;
}
freeaddrinfo(aitop);
if (!ai) {
error("connect %.100s port %u: %.100s", buf,
6000 + display_number, strerror(errno));
return -1;
}
set_nodelay(sock);
return sock;
}
/*
* Requests forwarding of X11 connections, generates fake authentication
* data, and enables authentication spoofing.
* This should be called in the client only.
*/
void
x11_request_forwarding_with_spoofing(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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