/* $OpenBSD: channels.c,v 1.440 2024/10/13 22:20:06 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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" /* XXX remove once we're satisfied there's no lurking bugs */ /* #define DEBUG_CHANNEL_POLL 1 */ /* -- agent forwarding */ #define NUM_SOCKS 10 /* -- X11 forwarding */ /* Maximum number of fake X11 displays to try. */ #define MAX_DISPLAYS 1000 /* Per-channel callback for pre/post IO actions */ typedef void chan_fn(struct ssh *, Channel *c); /* * 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; }; /* Used to record timeouts per channel type */ struct ssh_channel_timeout { char *type_pattern; int timeout_secs; }; /* 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; /* * 'channel_pre*' are called just before IO to add any bits * relevant to channels in the c->io_want bitmasks. * * 'channel_post*': perform any appropriate operations for * channels which have c->io_ready 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 */ time_t 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; /* Channel timeouts by type */ struct ssh_channel_timeout *timeouts; size_t ntimeouts; /* Global timeout for all OPEN channels */ int global_deadline; time_t lastused; }; /* 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_f("allocation failed"); 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_f("%d: bad id", id); return NULL; } c = ssh->chanctxt->channels[id]; if (c == NULL) { logit_f("%d: bad id: channel free", 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; } /* * Add a timeout for open channels whose c->ctype (or c->xctype if it is set) * match type_pattern. */ void channel_add_timeout(struct ssh *ssh, const char *type_pattern, int timeout_secs) { struct ssh_channels *sc = ssh->chanctxt; if (strcmp(type_pattern, "global") == 0) { debug2_f("global channel timeout %d seconds", timeout_secs); sc->global_deadline = timeout_secs; return; } debug2_f("channel type \"%s\" timeout %d seconds", type_pattern, timeout_secs); sc->timeouts = xrecallocarray(sc->timeouts, sc->ntimeouts, sc->ntimeouts + 1, sizeof(*sc->timeouts)); sc->timeouts[sc->ntimeouts].type_pattern = xstrdup(type_pattern); sc->timeouts[sc->ntimeouts].timeout_secs = timeout_secs; sc->ntimeouts++; } /* Clears all previously-added channel timeouts */ void channel_clear_timeouts(struct ssh *ssh) { struct ssh_channels *sc = ssh->chanctxt; size_t i; debug3_f("clearing"); for (i = 0; i < sc->ntimeouts; i++) free(sc->timeouts[i].type_pattern); free(sc->timeouts); sc->timeouts = NULL; sc->ntimeouts = 0; } static int lookup_timeout(struct ssh *ssh, const char *type) { struct ssh_channels *sc = ssh->chanctxt; size_t i; for (i = 0; i < sc->ntimeouts; i++) { if (match_pattern(type, sc->timeouts[i].type_pattern)) return sc->timeouts[i].timeout_secs; } return 0; } /* * Sets "extended type" of a channel; used by session layer to add additional * information about channel types (e.g. shell, login, subsystem) that can then * be used to select timeouts. * Will reset c->inactive_deadline as a side-effect. */ void channel_set_xtype(struct ssh *ssh, int id, const char *xctype) { Channel *c; if ((c = channel_by_id(ssh, id)) == NULL) fatal_f("missing channel %d", id); if (c->xctype != NULL) free(c->xctype); c->xctype = xstrdup(xctype); /* Type has changed, so look up inactivity deadline again */ c->inactive_deadline = lookup_timeout(ssh, c->xctype); debug2_f("labeled channel %d as %s (inactive timeout %u)", id, xctype, c->inactive_deadline); } /* * update "last used" time on a channel. * NB. nothing else should update lastused except to clear it. */ static void channel_set_used_time(struct ssh *ssh, Channel *c) { ssh->chanctxt->lastused = monotime(); if (c != NULL) c->lastused = ssh->chanctxt->lastused; } /* * Get the time at which a channel is due to time out for inactivity. * Returns 0 if the channel is not due to time out ever. */ static time_t channel_get_expiry(struct ssh *ssh, Channel *c) { struct ssh_channels *sc = ssh->chanctxt; time_t expiry = 0, channel_expiry; if (sc->lastused != 0 && sc->global_deadline != 0) expiry = sc->lastused + sc->global_deadline; if (c->lastused != 0 && c->inactive_deadline != 0) { channel_expiry = c->lastused + c->inactive_deadline; if (expiry == 0 || channel_expiry < expiry) expiry = channel_expiry; } return expiry; } /* * 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) { int val; if (rfd != -1) (void)fcntl(rfd, F_SETFD, FD_CLOEXEC); if (wfd != -1 && wfd != rfd) (void)fcntl(wfd, F_SETFD, FD_CLOEXEC); if (efd != -1 && efd != rfd && efd != wfd) (void)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); /* enable nonblocking mode */ c->restore_block = 0; if (nonblock == CHANNEL_NONBLOCK_STDIO) { /* * Special handling for stdio file descriptors: do not set * non-blocking mode if they are TTYs. Otherwise prepare to * restore their blocking state on exit to avoid interfering * with other programs that follow. */ if (rfd != -1 && !isatty(rfd) && (val = fcntl(rfd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) { c->restore_flags[0] = val; c->restore_block |= CHANNEL_RESTORE_RFD; set_nonblock(rfd); } if (wfd != -1 && !isatty(wfd) && (val = fcntl(wfd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) { c->restore_flags[1] = val; c->restore_block |= CHANNEL_RESTORE_WFD; set_nonblock(wfd); } if (efd != -1 && !isatty(efd) && (val = fcntl(efd, F_GETFL)) != -1 && !(val & O_NONBLOCK)) { c->restore_flags[2] = val; c->restore_block |= CHANNEL_RESTORE_EFD; set_nonblock(efd); } } else if (nonblock) { if (rfd != -1) set_nonblock(rfd); if (wfd != -1) set_nonblock(wfd); if (efd != -1) set_nonblock(efd); } /* channel might be entering a larval state, so reset global timeout */ channel_set_used_time(ssh, NULL); } /* * Allocate a new channel object and set its type and socket. */ Channel * channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd, u_int window, u_int maxpack, int extusage, const char *remote_name, int nonblock) { struct ssh_channels *sc = ssh->chanctxt; u_int i, found; Channel *c; int r; /* 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_f("internal error: channels_alloc %d too big", 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_f("sshbuf_new failed"); if ((r = sshbuf_set_max_size(c->input, CHAN_INPUT_MAX)) != 0) fatal_fr(r, "sshbuf_set_max_size"); 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 */ c->inactive_deadline = lookup_timeout(ssh, c->ctype); TAILQ_INIT(&c->status_confirms); debug("channel %d: new %s [%s] (inactive timeout: %u)", found, c->ctype, remote_name, c->inactive_deadline); return c; } int channel_close_fd(struct ssh *ssh, Channel *c, int *fdp) { int ret, fd = *fdp; if (fd == -1) return 0; /* restore blocking */ if (*fdp == c->rfd && (c->restore_block & CHANNEL_RESTORE_RFD) != 0) (void)fcntl(*fdp, F_SETFL, c->restore_flags[0]); else if (*fdp == c->wfd && (c->restore_block & CHANNEL_RESTORE_WFD) != 0) (void)fcntl(*fdp, F_SETFL, c->restore_flags[1]); else if (*fdp == c->efd && (c->restore_block & CHANNEL_RESTORE_EFD) != 0) (void)fcntl(*fdp, F_SETFL, c->restore_flags[2]); if (*fdp == c->rfd) { c->io_want &= ~SSH_CHAN_IO_RFD; c->io_ready &= ~SSH_CHAN_IO_RFD; c->rfd = -1; c->pfds[0] = -1; } if (*fdp == c->wfd) { c->io_want &= ~SSH_CHAN_IO_WFD; c->io_ready &= ~SSH_CHAN_IO_WFD; c->wfd = -1; c->pfds[1] = -1; } if (*fdp == c->efd) { c->io_want &= ~SSH_CHAN_IO_EFD; c->io_ready &= ~SSH_CHAN_IO_EFD; c->efd = -1; c->pfds[2] = -1; } if (*fdp == c->sock) { c->io_want &= ~SSH_CHAN_IO_SOCK; c->io_ready &= ~SSH_CHAN_IO_SOCK; c->sock = -1; c->pfds[3] = -1; } ret = close(fd); *fdp = -1; /* probably redundant */ 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, &c->sock); if (rfd != sock) channel_close_fd(ssh, c, &c->rfd); if (wfd != sock && wfd != rfd) channel_close_fd(ssh, c, &c->wfd); if (efd != sock && efd != rfd && efd != wfd) channel_close_fd(ssh, c, &c->efd); } static void fwd_perm_clear(struct permission *perm) { free(perm->host_to_connect); free(perm->listen_host); free(perm->listen_path); memset(perm, 0, sizeof(*perm)); } /* Returns an printable name for the specified forwarding permission list */ static const char * fwd_ident(int who, int where) { if (who == FORWARD_ADM) { if (where == FORWARD_LOCAL) return "admin local"; else if (where == FORWARD_REMOTE) return "admin remote"; } else if (who == FORWARD_USER) { if (where == FORWARD_LOCAL) return "user local"; else if (where == FORWARD_REMOTE) return "user remote"; } fatal("Unknown forward permission list %d/%d", who, where); } /* Returns the forwarding permission list for the specified direction */ static struct permission_set * permission_set_get(struct ssh *ssh, int where) { struct ssh_channels *sc = ssh->chanctxt; switch (where) { case FORWARD_LOCAL: return &sc->local_perms; break; case FORWARD_REMOTE: return &sc->remote_perms; break; default: fatal_f("invalid forwarding direction %d", where); } } /* Returns pointers to the specified forwarding list and its element count */ static void permission_set_get_array(struct ssh *ssh, int who, int where, struct permission ***permpp, u_int **npermpp) { struct permission_set *pset = permission_set_get(ssh, where); switch (who) { case FORWARD_USER: *permpp = &pset->permitted_user; *npermpp = &pset->num_permitted_user; break; case FORWARD_ADM: *permpp = &pset->permitted_admin; *npermpp = &pset->num_permitted_admin; break; default: fatal_f("invalid forwarding client %d", who); } } /* Adds an entry to the specified 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_f("%s overflow", 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_fr(r, "channel %i", c->self); } 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); free(c->mux_ctx); c->mux_ctx = NULL; } else if (c->type == SSH_CHANNEL_MUX_LISTENER) { free(c->mux_ctx); c->mux_ctx = NULL; } 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; free(c->xctype); c->xctype = NULL; while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) { if (cc->abandon_cb != NULL) cc->abandon_cb(ssh, c, cc->ctx); TAILQ_REMOVE(&c->status_confirms, cc, entry); freezero(cc, sizeof(*cc)); } if (c->filter_cleanup != NULL && c->filter_ctx != NULL) c->filter_cleanup(ssh, c->self, c->filter_ctx); sc->channels[c->self] = NULL; freezero(c, sizeof(*c)); } void channel_free_all(struct ssh *ssh) { u_int i; struct ssh_channels *sc = ssh->chanctxt; for (i = 0; i < sc->channels_alloc; i++) if (sc->channels[i] != NULL) channel_free(ssh, sc->channels[i]); free(sc->channels); sc->channels = NULL; sc->channels_alloc = 0; free(sc->x11_saved_display); sc->x11_saved_display = NULL; free(sc->x11_saved_proto); sc->x11_saved_proto = NULL; free(sc->x11_saved_data); sc->x11_saved_data = NULL; sc->x11_saved_data_len = 0; free(sc->x11_fake_data); sc->x11_fake_data = NULL; sc->x11_fake_data_len = 0; } /* * Closes the sockets/fds of all channels. This is used to close extra file * descriptors after a fork. */ void channel_close_all(struct ssh *ssh) { u_int i; for (i = 0; i < ssh->chanctxt->channels_alloc; i++) if (ssh->chanctxt->channels[i] != NULL) channel_close_fds(ssh, ssh->chanctxt->channels[i]); } /* * Stop listening to channels. */ void channel_stop_listening(struct ssh *ssh) { u_int i; Channel *c; for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { c = ssh->chanctxt->channels[i]; if (c != NULL) { switch (c->type) { case SSH_CHANNEL_AUTH_SOCKET: case SSH_CHANNEL_PORT_LISTENER: case SSH_CHANNEL_RPORT_LISTENER: case SSH_CHANNEL_X11_LISTENER: case SSH_CHANNEL_UNIX_LISTENER: case SSH_CHANNEL_RUNIX_LISTENER: channel_close_fd(ssh, c, &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_f("bad channel type %d", c->type); /* NOTREACHED */ } } return 0; } /* Returns true if a channel with a TTY is open. */ int channel_tty_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->type != SSH_CHANNEL_OPEN) continue; if (c->client_tty) return 1; } 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_f("bad channel type %d", 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] %s%u %s%u i%u/%zu o%u/%zu e[%s]/%zu " "fd %d/%d/%d sock %d cc %d %s%u io 0x%02x/0x%02x", c->type, c->xctype != NULL ? c->xctype : c->ctype, c->have_remote_id ? "r" : "nr", c->remote_id, c->mux_ctx != NULL ? "m" : "nm", c->mux_downstream_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, c->have_ctl_child_id ? "c" : "nc", c->ctl_child_id, c->io_want, c->io_ready); 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_f("sshbuf_new"); if ((r = sshbuf_putf(buf, "The following connections are open:\r\n")) != 0) fatal_fr(r, "sshbuf_putf"); 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_fr(r, "sshbuf_putf"); } free(cp); continue; default: fatal_f("bad channel type %d", c->type); /* NOTREACHED */ } } if ((ret = sshbuf_dup_string(buf)) == NULL) fatal_f("sshbuf_dup_string"); 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_r(r, "%s: channel %i: open", where, c->self); } } 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_fr(r, "channel %i", c->self); } 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_f("%d: unknown channel id", id); return; } if (!c->have_remote_id) fatal_f("channel %d: no remote id", 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_fr(r, "channel %i", c->self); } } 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_f("%d: bad id", id); cc = xcalloc(1, sizeof(*cc)); cc->cb = cb; cc->abandon_cb = abandon_cb; cc->ctx = ctx; TAILQ_INSERT_TAIL(&c->status_confirms, cc, entry); } void channel_register_open_confirm(struct ssh *ssh, int id, channel_open_fn *fn, void *ctx) { Channel *c = channel_lookup(ssh, id); if (c == NULL) { logit_f("%d: bad id", 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_f("%d: bad id", 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_f("%d: bad id", 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_f("%d: bad id", id); return; } c->input_filter = ifn; c->output_filter = ofn; c->filter_ctx = ctx; c->filter_cleanup = cfn; } void channel_set_fds(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_f("channel %d: no remote id", c->self); channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, is_tty); c->type = SSH_CHANNEL_OPEN; channel_set_used_time(ssh, c); 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_fr(r, "channel %i", c->self); } static void channel_pre_listener(struct ssh *ssh, Channel *c) { c->io_want = SSH_CHAN_IO_SOCK_R; } static void channel_pre_connecting(struct ssh *ssh, Channel *c) { debug3("channel %d: waiting for connection", c->self); c->io_want = SSH_CHAN_IO_SOCK_W; } static void channel_pre_open(struct ssh *ssh, Channel *c) { c->io_want = 0; 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) c->io_want |= SSH_CHAN_IO_RFD; if (c->ostate == CHAN_OUTPUT_OPEN || c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { if (sshbuf_len(c->output) > 0) { c->io_want |= SSH_CHAN_IO_WFD; } 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) c->io_want |= SSH_CHAN_IO_EFD_W; 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) c->io_want |= SSH_CHAN_IO_EFD_R; } /* 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 && 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; } void channel_force_close(struct ssh *ssh, Channel *c, int abandon) { debug3_f("channel %d: forcibly closing", c->self); if (c->istate == CHAN_INPUT_OPEN) chan_read_failed(ssh, c); if (c->istate == CHAN_INPUT_WAIT_DRAIN) { sshbuf_reset(c->input); chan_ibuf_empty(ssh, c); } if (c->ostate == CHAN_OUTPUT_OPEN || c->ostate == CHAN_OUTPUT_WAIT_DRAIN) { sshbuf_reset(c->output); chan_write_failed(ssh, c); } if (c->detach_user) c->detach_user(ssh, c->self, 1, NULL); if (c->efd != -1) channel_close_fd(ssh, c, &c->efd); if (abandon) c->type = SSH_CHANNEL_ABANDONED; /* exempt from inactivity timeouts */ c->inactive_deadline = 0; c->lastused = 0; } static void channel_pre_x11_open(struct ssh *ssh, Channel *c) { int ret = x11_open_helper(ssh, c->output); /* c->force_drain = 1; */ if (ret == 1) { c->type = SSH_CHANNEL_OPEN; channel_set_used_time(ssh, c); channel_pre_open(ssh, c); } 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); channel_force_close(ssh, c, 0); } } static void channel_pre_mux_client(struct ssh *ssh, Channel *c) { c->io_want = 0; if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause && sshbuf_check_reserve(c->input, CHAN_RBUF) == 0) c->io_want |= SSH_CHAN_IO_RFD; 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) c->io_want |= SSH_CHAN_IO_WFD; 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_r(r, "channels %d: decode socks4", c->self); return -1; } have = sshbuf_len(input); p = sshbuf_ptr(input); if (memchr(p, '\0', have) == NULL) { error("channel %d: decode socks4: unterminated user", 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_fr(r, "channel %d: consume", c->self); 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_fr(r, "channel %d: consume", c->self); } 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_fr(r, "channel %d: append reply", c->self); 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_fr(r, "channel %d: consume", c->self); /* version, method */ if ((r = sshbuf_put_u8(output, 0x05)) != 0 || (r = sshbuf_put_u8(output, SSH_SOCKS5_NOAUTH)) != 0) fatal_fr(r, "channel %d: append reply", c->self); 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_fr(r, "channel %d: consume", c->self); if (s5_req.atyp == SSH_SOCKS5_DOMAIN) { /* host string length */ if ((r = sshbuf_consume(input, 1)) != 0) fatal_fr(r, "channel %d: consume", c->self); } if ((r = sshbuf_get(input, &dest_addr, addrlen)) != 0 || (r = sshbuf_get(input, &dest_port, 2)) != 0) { debug_r(r, "channel %d: parse addr/port", c->self); 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_fr(r, "channel %d: append reply", c->self); return 1; } Channel * channel_connect_stdio_fwd(struct ssh *ssh, const char *host_to_connect, int port_to_connect, int in, int out, int nonblock) { Channel *c; debug_f("%s:%d", 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); 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, port_to_connect == PORT_STREAMLOCAL ? "direct-streamlocal@openssh.com" : "direct-tcpip"); return c; } /* dynamic port forwarding */ static void channel_pre_dynamic(struct ssh *ssh, Channel *c) { const u_char *p; u_int have; int ret; c->io_want = 0; 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 */ c->io_want |= SSH_CHAN_IO_RFD; 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 */ c->io_want |= SSH_CHAN_IO_RFD; if (sshbuf_len(c->output)) c->io_want |= SSH_CHAN_IO_WFD; } 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; channel_force_close(ssh, c, 0); } /* reverse dynamic port forwarding */ static void channel_before_prepare_io_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_fr(r, "channel %d: consume", c->self); 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_fr(r, "channel %i: rdynamic", c->self); } if ((r = sshbuf_consume(c->input, len)) != 0) fatal_fr(r, "channel %d: consume", c->self); 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) { Channel *nc; struct sockaddr_storage addr; int r, newsock, oerrno, remote_port; socklen_t addrlen; char buf[16384], *remote_ipaddr; if ((c->io_ready & SSH_CHAN_IO_SOCK_R) == 0) 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, &c->sock); chan_mark_dead(ssh, c); errno = oerrno; } if (newsock == -1) { if (errno != EINTR && errno != EWOULDBLOCK && errno != ECONNABORTED) error("accept: %.100s", strerror(errno)); if (errno == EMFILE || errno == ENFILE) c->notbefore = monotime() + 1; return; } set_nodelay(newsock); remote_ipaddr = get_peer_ipaddr(newsock); remote_port = get_peer_port(newsock); snprintf(buf, sizeof buf, "X11 connection from %.200s port %d", remote_ipaddr, remote_port); nc = channel_new(ssh, "x11-connection", 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_fr(r, "channel %i: reply", c->self); } if ((r = sshpkt_send(ssh)) != 0) fatal_fr(r, "channel %i: send", c->self); 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_fr(r, "channel %i: reply", c->self); } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) { /* target path */ if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) fatal_fr(r, "channel %i: reply", c->self); } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) { /* listen path */ if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) fatal_fr(r, "channel %i: reply", c->self); } else { /* listen address, port */ if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 || (r = sshpkt_put_u32(ssh, local_port)) != 0) fatal_fr(r, "channel %i: reply", c->self); } if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) { /* reserved for future owner/mode info */ if ((r = sshpkt_put_cstring(ssh, "")) != 0) fatal_fr(r, "channel %i: reply", c->self); } 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_fr(r, "channel %i: reply", c->self); } if ((r = sshpkt_send(ssh)) != 0) fatal_fr(r, "channel %i: send", c->self); free(remote_ipaddr); free(local_ipaddr); } void channel_set_x11_refuse_time(struct ssh *ssh, time_t 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) { Channel *nc; struct sockaddr_storage addr; int newsock, nextstate; socklen_t addrlen; char *rtype; if ((c->io_ready & SSH_CHAN_IO_SOCK_R) == 0) return; debug("Connection to port %d forwarding to %.100s port %d requested.", c->listening_port, c->path, c->host_port); if (c->type == SSH_CHANNEL_RPORT_LISTENER) { nextstate = SSH_CHANNEL_OPENING; rtype = "forwarded-tcpip"; } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) { nextstate = SSH_CHANNEL_OPENING; rtype = "forwarded-streamlocal@openssh.com"; } else if (c->host_port == PORT_STREAMLOCAL) { nextstate = SSH_CHANNEL_OPENING; rtype = "direct-streamlocal@openssh.com"; } else if (c->host_port == 0) { nextstate = SSH_CHANNEL_DYNAMIC; rtype = "dynamic-tcpip"; } else { nextstate = SSH_CHANNEL_OPENING; rtype = "direct-tcpip"; } addrlen = sizeof(addr); newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen); if (newsock == -1) { if (errno != EINTR && errno != EWOULDBLOCK && errno != ECONNABORTED) error("accept: %.100s", strerror(errno)); if (errno == EMFILE || errno == ENFILE) c->notbefore = monotime() + 1; return; } if (c->host_port != PORT_STREAMLOCAL) set_nodelay(newsock); nc = channel_new(ssh, rtype, nextstate, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, 0, rtype, 1); nc->listening_port = c->listening_port; nc->host_port = c->host_port; if (c->path != NULL) nc->path = xstrdup(c->path); if (nextstate != SSH_CHANNEL_DYNAMIC) port_open_helper(ssh, nc, rtype); } /* * This is the authentication agent socket listening for connections from * clients. */ static void channel_post_auth_listener(struct ssh *ssh, Channel *c) { Channel *nc; int r, newsock; struct sockaddr_storage addr; socklen_t addrlen; if ((c->io_ready & SSH_CHAN_IO_SOCK_R) == 0) return; addrlen = sizeof(addr); newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen); if (newsock == -1) { error("accept from auth socket: %.100s", strerror(errno)); if (errno == EMFILE || errno == ENFILE) c->notbefore = monotime() + 1; return; } nc = channel_new(ssh, "agent-connection", 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_fr(r, "channel %i", c->self); } static void channel_post_connecting(struct ssh *ssh, Channel *c) { int err = 0, sock, isopen, r; socklen_t sz = sizeof(err); if ((c->io_ready & SSH_CHAN_IO_SOCK_W) == 0) return; if (!c->have_remote_id) fatal_f("channel %d: no remote id", c->self); /* for rdynamic the OPEN_CONFIRMATION has been sent already */ isopen = (c->type == SSH_CHANNEL_RDYNAMIC_FINISH); if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) == -1) { err = errno; error("getsockopt SO_ERROR failed"); } if (err == 0) { /* Non-blocking connection completed */ 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; channel_set_used_time(ssh, c); 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 || (r = sshpkt_send(ssh)) != 0) fatal_fr(r, "channel %i open confirm", c->self); } return; } if (err == EINTR || err == EAGAIN || err == EINPROGRESS) return; /* Non-blocking connection failed */ debug("channel %d: connection failed: %s", c->self, strerror(err)); /* Try next address, if any */ if ((sock = connect_next(&c->connect_ctx)) == -1) { /* Exhausted all addresses for this destination */ 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 || (r = sshpkt_send(ssh)) != 0) fatal_fr(r, "channel %i: failure", c->self); chan_mark_dead(ssh, c); } } /* New non-blocking connection in progress */ close(c->sock); c->sock = c->rfd = c->wfd = sock; } static int channel_handle_rfd(struct ssh *ssh, Channel *c) { char buf[CHAN_RBUF]; ssize_t len; int r; size_t nr = 0, have, avail, maxlen = CHANNEL_MAX_READ; if ((c->io_ready & SSH_CHAN_IO_RFD) == 0) return 1; /* Shouldn't happen */ if ((avail = sshbuf_avail(c->input)) == 0) return 1; /* Shouldn't happen */ /* * For "simple" channels (i.e. not datagram or filtered), we can * read directly to the channel buffer. */ if (c->input_filter == NULL && !c->datagram) { /* Only OPEN channels have valid rwin */ if (c->type == SSH_CHANNEL_OPEN) { if ((have = sshbuf_len(c->input)) >= c->remote_window) return 1; /* shouldn't happen */ if (maxlen > c->remote_window - have) maxlen = c->remote_window - have; } if (maxlen > avail) maxlen = avail; if ((r = sshbuf_read(c->rfd, c->input, maxlen, &nr)) != 0) { if (errno == EINTR || errno == EAGAIN) return 1; debug2("channel %d: read failed rfd %d maxlen %zu: %s", c->self, c->rfd, maxlen, ssh_err(r)); goto rfail; } if (nr != 0) channel_set_used_time(ssh, c); return 1; } len = read(c->rfd, buf, sizeof(buf)); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug2("channel %d: read<=0 rfd %d len %zd: %s", c->self, c->rfd, len, len == 0 ? "closed" : strerror(errno)); rfail: 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; } channel_set_used_time(ssh, c); 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_fr(r, "channel %i: put datagram", c->self); } return 1; } static int channel_handle_wfd(struct ssh *ssh, Channel *c) { struct termios tio; u_char *data = NULL, *buf; /* XXX const; need filter API change */ size_t dlen, olen = 0; int r, len; if ((c->io_ready & SSH_CHAN_IO_WFD) == 0) return 1; if (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_fr(r, "channel %i: get datagram", c->self); buf = data; } else { buf = data = sshbuf_mutable_ptr(c->output); dlen = sshbuf_len(c->output); } if (c->datagram) { /* ignore truncated writes, datagrams might get lost */ len = write(c->wfd, buf, dlen); free(data); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) goto write_fail; goto out; } len = write(c->wfd, buf, dlen); if (len == -1 && (errno == EINTR || errno == EAGAIN)) 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; } channel_set_used_time(ssh, c); 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_fr(r, "channel %i: ignore", c->self); } } if ((r = sshbuf_consume(c->output, len)) != 0) fatal_fr(r, "channel %i: consume", c->self); out: c->local_consumed += olen - sshbuf_len(c->output); return 1; } static int channel_handle_efd_write(struct ssh *ssh, Channel *c) { int r; ssize_t len; if ((c->io_ready & SSH_CHAN_IO_EFD_W) == 0) return 1; if (sshbuf_len(c->extended) == 0) return 1; len = write(c->efd, sshbuf_ptr(c->extended), sshbuf_len(c->extended)); debug2("channel %d: written %zd to efd %d", c->self, len, c->efd); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug2("channel %d: closing write-efd %d", c->self, c->efd); channel_close_fd(ssh, c, &c->efd); } else { if ((r = sshbuf_consume(c->extended, len)) != 0) fatal_fr(r, "channel %i: consume", c->self); c->local_consumed += len; channel_set_used_time(ssh, c); } return 1; } static int channel_handle_efd_read(struct ssh *ssh, Channel *c) { char buf[CHAN_RBUF]; int r; ssize_t len; if ((c->io_ready & SSH_CHAN_IO_EFD_R) == 0) return 1; len = read(c->efd, buf, sizeof(buf)); debug2("channel %d: read %zd from efd %d", c->self, len, c->efd); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return 1; if (len <= 0) { debug2("channel %d: closing read-efd %d", c->self, c->efd); channel_close_fd(ssh, c, &c->efd); return 1; } channel_set_used_time(ssh, c); 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_fr(r, "channel %i: append", c->self); return 1; } static int channel_handle_efd(struct ssh *ssh, Channel *c) { 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); else if (c->extended_usage == CHAN_EXTENDED_READ || c->extended_usage == CHAN_EXTENDED_IGNORE) return channel_handle_efd_read(ssh, c); 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_f("channel %d: no remote id", 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_fr(r, "channel %i", c->self); } 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) { channel_handle_rfd(ssh, c); channel_handle_wfd(ssh, c); channel_handle_efd(ssh, c); channel_check_window(ssh, c); } static u_int read_mux(struct ssh *ssh, Channel *c, u_int need) { char buf[CHAN_RBUF]; ssize_t len; u_int rlen; int r; if (sshbuf_len(c->input) < need) { rlen = need - sshbuf_len(c->input); len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF)); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return sshbuf_len(c->input); if (len <= 0) { debug2("channel %d: ctl read<=0 rfd %d len %zd", c->self, c->rfd, len); chan_read_failed(ssh, c); return 0; } else if ((r = sshbuf_put(c->input, buf, len)) != 0) fatal_fr(r, "channel %i: append", c->self); } return sshbuf_len(c->input); } static void channel_post_mux_client_read(struct ssh *ssh, Channel *c) { u_int need; if ((c->io_ready & SSH_CHAN_IO_RFD) == 0) 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) { ssize_t len; int r; if ((c->io_ready & SSH_CHAN_IO_WFD) == 0) return; if (sshbuf_len(c->output) == 0) return; len = write(c->wfd, sshbuf_ptr(c->output), sshbuf_len(c->output)); if (len == -1 && (errno == EINTR || errno == EAGAIN)) return; if (len <= 0) { chan_mark_dead(ssh, c); return; } if ((r = sshbuf_consume(c->output, len)) != 0) fatal_fr(r, "channel %i: consume", c->self); } static void channel_post_mux_client(struct ssh *ssh, Channel *c) { channel_post_mux_client_read(ssh, c); channel_post_mux_client_write(ssh, c); } static void channel_post_mux_listener(struct ssh *ssh, Channel *c) { Channel *nc; struct sockaddr_storage addr; socklen_t addrlen; int newsock; uid_t euid; gid_t egid; if ((c->io_ready & SSH_CHAN_IO_SOCK_R) == 0) 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_f("accept: %s", strerror(errno)); if (errno == EMFILE || errno == ENFILE) c->notbefore = monotime() + 1; return; } if (getpeereid(newsock, &euid, &egid) == -1) { error_f("getpeereid failed: %s", 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, "mux-control", 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_f("new mux channel %d fd %d", 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_f("allocation failed"); 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, 0, 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, struct timespec *timeout) { 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(); for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) { c = sc->channels[i]; if (c == NULL) continue; /* Try to keep IO going while rekeying */ if (ssh_packet_is_rekeying(ssh) && c->type != SSH_CHANNEL_OPEN) continue; if (c->delayed) { if (table == CHAN_PRE) c->delayed = 0; else continue; } if (ftab[c->type] != NULL) { if (table == CHAN_PRE && c->type == SSH_CHANNEL_OPEN && channel_get_expiry(ssh, c) != 0 && now >= channel_get_expiry(ssh, c)) { /* channel closed for inactivity */ verbose("channel %d: closing after %u seconds " "of inactivity", c->self, c->inactive_deadline); channel_force_close(ssh, c, 1); } else if (c->notbefore <= now) { /* Run handlers that are not paused. */ (*ftab[c->type])(ssh, c); /* inactivity timeouts must interrupt poll() */ if (timeout != NULL && c->type == SSH_CHANNEL_OPEN && channel_get_expiry(ssh, c) != 0) { ptimeout_deadline_monotime(timeout, channel_get_expiry(ssh, c)); } } else if (timeout != NULL) { /* * Arrange for poll() wakeup when channel pause * timer expires. */ ptimeout_deadline_monotime(timeout, c->notbefore); } } channel_garbage_collect(ssh, c); } } /* * Create sockets before preparing IO. * This is necessary for things that need to happen after reading * the network-input but need to be completed before IO event setup, e.g. * because they may create new channels. */ static void channel_before_prepare_io(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_io_rdynamic(ssh, c); } } static void dump_channel_poll(const char *func, const char *what, Channel *c, u_int pollfd_offset, struct pollfd *pfd) { #ifdef DEBUG_CHANNEL_POLL debug3("%s: channel %d: %s r%d w%d e%d s%d c->pfds [ %d %d %d %d ] " "io_want 0x%02x io_ready 0x%02x pfd[%u].fd=%d " "pfd.ev 0x%02x pfd.rev 0x%02x", func, c->self, what, c->rfd, c->wfd, c->efd, c->sock, c->pfds[0], c->pfds[1], c->pfds[2], c->pfds[3], c->io_want, c->io_ready, pollfd_offset, pfd->fd, pfd->events, pfd->revents); #endif } /* Prepare pollfd entries for a single channel */ static void channel_prepare_pollfd(Channel *c, u_int *next_pollfd, struct pollfd *pfd, u_int npfd) { u_int ev, p = *next_pollfd; if (c == NULL) return; if (p + 4 > npfd) { /* Shouldn't happen */ fatal_f("channel %d: bad pfd offset %u (max %u)", c->self, p, npfd); } c->pfds[0] = c->pfds[1] = c->pfds[2] = c->pfds[3] = -1; /* * prepare c->rfd * * This is a special case, since c->rfd might be the same as * c->wfd, c->efd and/or c->sock. Handle those here if they want * IO too. */ if (c->rfd != -1) { ev = 0; if ((c->io_want & SSH_CHAN_IO_RFD) != 0) ev |= POLLIN; /* rfd == wfd */ if (c->wfd == c->rfd) { if ((c->io_want & SSH_CHAN_IO_WFD) != 0) ev |= POLLOUT; } /* rfd == efd */ if (c->efd == c->rfd) { if ((c->io_want & SSH_CHAN_IO_EFD_R) != 0) ev |= POLLIN; if ((c->io_want & SSH_CHAN_IO_EFD_W) != 0) ev |= POLLOUT; } /* rfd == sock */ if (c->sock == c->rfd) { if ((c->io_want & SSH_CHAN_IO_SOCK_R) != 0) ev |= POLLIN; if ((c->io_want & SSH_CHAN_IO_SOCK_W) != 0) ev |= POLLOUT; } /* Pack a pfd entry if any event armed for this fd */ if (ev != 0) { c->pfds[0] = p; pfd[p].fd = c->rfd; pfd[p].events = ev; dump_channel_poll(__func__, "rfd", c, p, &pfd[p]); p++; } } /* prepare c->wfd if wanting IO and not already handled above */ if (c->wfd != -1 && c->rfd != c->wfd) { ev = 0; if ((c->io_want & SSH_CHAN_IO_WFD)) ev |= POLLOUT; /* Pack a pfd entry if any event armed for this fd */ if (ev != 0) { c->pfds[1] = p; pfd[p].fd = c->wfd; pfd[p].events = ev; dump_channel_poll(__func__, "wfd", c, p, &pfd[p]); p++; } } /* prepare c->efd if wanting IO and not already handled above */ if (c->efd != -1 && c->rfd != c->efd) { ev = 0; if ((c->io_want & SSH_CHAN_IO_EFD_R) != 0) ev |= POLLIN; if ((c->io_want & SSH_CHAN_IO_EFD_W) != 0) ev |= POLLOUT; /* Pack a pfd entry if any event armed for this fd */ if (ev != 0) { c->pfds[2] = p; pfd[p].fd = c->efd; pfd[p].events = ev; dump_channel_poll(__func__, "efd", c, p, &pfd[p]); p++; } } /* prepare c->sock if wanting IO and not already handled above */ if (c->sock != -1 && c->rfd != c->sock) { ev = 0; if ((c->io_want & SSH_CHAN_IO_SOCK_R) != 0) ev |= POLLIN; if ((c->io_want & SSH_CHAN_IO_SOCK_W) != 0) ev |= POLLOUT; /* Pack a pfd entry if any event armed for this fd */ if (ev != 0) { c->pfds[3] = p; pfd[p].fd = c->sock; pfd[p].events = 0; dump_channel_poll(__func__, "sock", c, p, &pfd[p]); p++; } } *next_pollfd = p; } /* * Allocate/prepare poll structure */ void channel_prepare_poll(struct ssh *ssh, struct pollfd **pfdp, u_int *npfd_allocp, u_int *npfd_activep, u_int npfd_reserved, struct timespec *timeout) { struct ssh_channels *sc = ssh->chanctxt; u_int i, oalloc, p, npfd = npfd_reserved; channel_before_prepare_io(ssh); /* might create a new channel */ /* clear out I/O flags from last poll */ for (i = 0; i < sc->channels_alloc; i++) { if (sc->channels[i] == NULL) continue; sc->channels[i]->io_want = sc->channels[i]->io_ready = 0; } /* Allocate 4x pollfd for each channel (rfd, wfd, efd, sock) */ if (sc->channels_alloc >= (INT_MAX / 4) - npfd_reserved) fatal_f("too many channels"); /* shouldn't happen */ npfd += sc->channels_alloc * 4; if (npfd > *npfd_allocp) { *pfdp = xrecallocarray(*pfdp, *npfd_allocp, npfd, sizeof(**pfdp)); *npfd_allocp = npfd; } *npfd_activep = npfd_reserved; oalloc = sc->channels_alloc; channel_handler(ssh, CHAN_PRE, timeout); if (oalloc != sc->channels_alloc) { /* shouldn't happen */ fatal_f("channels_alloc changed during CHAN_PRE " "(was %u, now %u)", oalloc, sc->channels_alloc); } /* Prepare pollfd */ p = npfd_reserved; for (i = 0; i < sc->channels_alloc; i++) channel_prepare_pollfd(sc->channels[i], &p, *pfdp, npfd); *npfd_activep = p; } static void fd_ready(Channel *c, int p, struct pollfd *pfds, u_int npfd, int fd, const char *what, u_int revents_mask, u_int ready) { struct pollfd *pfd = &pfds[p]; if (fd == -1) return; if (p == -1 || (u_int)p >= npfd) fatal_f("channel %d: bad pfd %d (max %u)", c->self, p, npfd); dump_channel_poll(__func__, what, c, p, pfd); if (pfd->fd != fd) { fatal("channel %d: inconsistent %s fd=%d pollfd[%u].fd %d " "r%d w%d e%d s%d", c->self, what, fd, p, pfd->fd, c->rfd, c->wfd, c->efd, c->sock); } if ((pfd->revents & POLLNVAL) != 0) { fatal("channel %d: invalid %s pollfd[%u].fd %d r%d w%d e%d s%d", c->self, what, p, pfd->fd, c->rfd, c->wfd, c->efd, c->sock); } if ((pfd->revents & (revents_mask|POLLHUP|POLLERR)) != 0) c->io_ready |= ready & c->io_want; } /* * After poll, perform any appropriate operations for channels which have * events pending. */ void channel_after_poll(struct ssh *ssh, struct pollfd *pfd, u_int npfd) { struct ssh_channels *sc = ssh->chanctxt; u_int i; int p; Channel *c; #ifdef DEBUG_CHANNEL_POLL for (p = 0; p < (int)npfd; p++) { if (pfd[p].revents == 0) continue; debug_f("pfd[%u].fd %d rev 0x%04x", p, pfd[p].fd, pfd[p].revents); } #endif /* Convert pollfd into c->io_ready */ for (i = 0; i < sc->channels_alloc; i++) { c = sc->channels[i]; if (c == NULL) continue; /* if rfd is shared with efd/sock then wfd should be too */ if (c->rfd != -1 && c->wfd != -1 && c->rfd != c->wfd && (c->rfd == c->efd || c->rfd == c->sock)) { /* Shouldn't happen */ fatal_f("channel %d: unexpected fds r%d w%d e%d s%d", c->self, c->rfd, c->wfd, c->efd, c->sock); } c->io_ready = 0; /* rfd, potentially shared with wfd, efd and sock */ if (c->rfd != -1 && (p = c->pfds[0]) != -1) { fd_ready(c, p, pfd, npfd, c->rfd, "rfd", POLLIN, SSH_CHAN_IO_RFD); if (c->rfd == c->wfd) { fd_ready(c, p, pfd, npfd, c->wfd, "wfd/r", POLLOUT, SSH_CHAN_IO_WFD); } if (c->rfd == c->efd) { fd_ready(c, p, pfd, npfd, c->efd, "efdr/r", POLLIN, SSH_CHAN_IO_EFD_R); fd_ready(c, p, pfd, npfd, c->efd, "efdw/r", POLLOUT, SSH_CHAN_IO_EFD_W); } if (c->rfd == c->sock) { fd_ready(c, p, pfd, npfd, c->sock, "sockr/r", POLLIN, SSH_CHAN_IO_SOCK_R); fd_ready(c, p, pfd, npfd, c->sock, "sockw/r", POLLOUT, SSH_CHAN_IO_SOCK_W); } dump_channel_poll(__func__, "rfd", c, p, pfd); } /* wfd */ if (c->wfd != -1 && c->wfd != c->rfd && (p = c->pfds[1]) != -1) { fd_ready(c, p, pfd, npfd, c->wfd, "wfd", POLLOUT, SSH_CHAN_IO_WFD); dump_channel_poll(__func__, "wfd", c, p, pfd); } /* efd */ if (c->efd != -1 && c->efd != c->rfd && (p = c->pfds[2]) != -1) { fd_ready(c, p, pfd, npfd, c->efd, "efdr", POLLIN, SSH_CHAN_IO_EFD_R); fd_ready(c, p, pfd, npfd, c->efd, "efdw", POLLOUT, SSH_CHAN_IO_EFD_W); dump_channel_poll(__func__, "efd", c, p, pfd); } /* sock */ if (c->sock != -1 && c->sock != c->rfd && (p = c->pfds[3]) != -1) { fd_ready(c, p, pfd, npfd, c->sock, "sockr", POLLIN, SSH_CHAN_IO_SOCK_R); fd_ready(c, p, pfd, npfd, c->sock, "sockw", POLLOUT, SSH_CHAN_IO_SOCK_W); dump_channel_poll(__func__, "sock", c, p, pfd); } } channel_handler(ssh, CHAN_POST, NULL); } /* * Enqueue data for channels with open or draining c->input. * Returns non-zero if a packet was enqueued. */ static int 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 0; } if (!c->have_remote_id) fatal_f("channel %d: no remote id", c->self); if (c->datagram) { /* Check datagram will fit; drop if not */ if ((r = sshbuf_get_string_direct(c->input, &pkt, &plen)) != 0) fatal_fr(r, "channel %i: get datagram", c->self); /* * 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 0; } /* 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_fr(r, "channel %i: send datagram", c->self); c->remote_window -= plen; return 1; } /* 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 0; 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_fr(r, "channel %i: send data", c->self); if ((r = sshbuf_consume(c->input, len)) != 0) fatal_fr(r, "channel %i: consume", c->self); c->remote_window -= len; return 1; } /* * Enqueue data for channels with open c->extended in read mode. * Returns non-zero if a packet was enqueued. */ static int channel_output_poll_extended_read(struct ssh *ssh, Channel *c) { size_t len; int r; if ((len = sshbuf_len(c->extended)) == 0) return 0; 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 0; if (!c->have_remote_id) fatal_f("channel %d: no remote id", 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_fr(r, "channel %i: data", c->self); if ((r = sshbuf_consume(c->extended, len)) != 0) fatal_fr(r, "channel %i: consume", c->self); c->remote_window -= len; debug2("channel %d: sent ext data %zu", c->self, len); return 1; } /* * If there is data to send to the connection, enqueue some of it now. * Returns non-zero if data was enqueued. */ int channel_output_poll(struct ssh *ssh) { struct ssh_channels *sc = ssh->chanctxt; Channel *c; u_int i; int ret = 0; 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) ret |= 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) ret |= channel_output_poll_extended_read(ssh, c); } return ret; } /* -- 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_fr(r, "parse"); return -1; } if (have < 2) { error_f("short message"); return -1; } type = cp[1]; /* skip padlen + type */ cp += 2; have -= 2; if (ssh_packet_log_type(type)) debug3_f("channel %u: down->up: type %u", downstream->self, type); switch (type) { case SSH2_MSG_CHANNEL_OPEN: if ((original = sshbuf_from(cp, have)) == NULL || (modified = sshbuf_new()) == NULL) { error_f("alloc"); goto out; } if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 || (r = sshbuf_get_u32(original, &id)) != 0) { error_fr(r, "parse"); 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_fr(r, "compose"); 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_f("alloc"); goto out; } if ((r = sshbuf_get_u32(original, &remote_id)) != 0 || (r = sshbuf_get_u32(original, &id)) != 0) { error_fr(r, "parse"); 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_fr(r, "compose"); channel_free(ssh, c); goto out; } break; case SSH2_MSG_GLOBAL_REQUEST: if ((original = sshbuf_from(cp, have)) == NULL) { error_f("alloc"); goto out; } if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) { error_fr(r, "parse"); goto out; } if (strcmp(ctype, "tcpip-forward") != 0) { error_f("unsupported request %s", 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_fr(r, "parse"); goto out; } if (listen_port > 65535) { error_f("tcpip-forward for %s: bad port %u", listen_host, listen_port); goto out; } /* Record that connection to this host/port is permitted. */ permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, "", -1, listen_host, NULL, (int)listen_port, downstream); 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_fr(r, "send"); goto out; } } else { if ((r = sshpkt_start(ssh, type)) != 0 || (r = sshpkt_put(ssh, cp, have)) != 0 || (r = sshpkt_send(ssh)) != 0) { error_fr(r, "send"); 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_f("channel %u: unsupported type %u", c->self, type); return 0; } if ((b = sshbuf_new()) == NULL) { error_f("alloc reply"); goto out; } /* get remaining payload (after id) */ cp = sshpkt_ptr(ssh, &len); if (cp == NULL) { error_f("no packet"); 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_fr(r, "compose muxclient"); goto out; } /* sshbuf_dump(b, stderr); */ if (ssh_packet_log_type(type)) debug3_f("channel %u: up->down: type %u", 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_r(r, "%s: parse id", where); ssh_packet_disconnect(ssh, "Invalid %s message", what); } if (id > INT_MAX) { error_r(r, "%s: bad channel id %u", where, id); 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_fr(r, "channel %i: get data", c->self); 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) { c->local_window_exceeded += win_len - c->local_window; logit("channel %d: rcvd too much data %zu, win %u/%u " "(excess %u)", c->self, win_len, c->local_window, c->local_window_max, c->local_window_exceeded); c->local_window = 0; /* Allow 10% grace before bringing the hammer down */ if (c->local_window_exceeded > (c->local_window_max / 10)) { ssh_packet_disconnect(ssh, "channel %d: peer ignored " "channel window", c->self); } } else { c->local_window -= win_len; c->local_window_exceeded = 0; } if (c->datagram) { if ((r = sshbuf_put_string(c->output, data, data_len)) != 0) fatal_fr(r, "channel %i: append datagram", c->self); } else if ((r = sshbuf_put(c->output, data, data_len)) != 0) fatal_fr(r, "channel %i: append data", c->self); 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 (ssh->compat & 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_fr(r, "parse tcode"); 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_fr(r, "parse data"); 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_fr(r, "append"); 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_fr(r, "parse data"); 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_fr(r, "parse data"); 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_fr(r, "window/maxpacket"); 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_f("channel %d: callback start", c->self); c->open_confirm(ssh, c->self, 1, c->open_confirm_ctx); debug2_f("channel %d: callback done", c->self); } channel_set_used_time(ssh, c); 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_fr(r, "parse reason"); 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_fr(r, "parse msg/lang"); 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_f("channel %d: callback start", c->self); c->open_confirm(ssh, c->self, 0, c->open_confirm_ctx); debug2_f("channel %d: callback done", 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_fr(r, "parse adjust"); ssh_packet_disconnect(ssh, "Invalid window adjust message"); } debug2("channel %d: rcvd adjust %u", c->self, adjust); if ((new_rwin = c->remote_window + adjust) < c->remote_window) { fatal("channel %d: adjust %u overflows remote window %u", c->self, adjust, c->remote_window); } c->remote_window = new_rwin; return 0; } int channel_input_status_confirm(int type, u_int32_t seq, struct ssh *ssh) { int id = channel_parse_id(ssh, __func__, "status confirm"); Channel *c; struct channel_confirm *cc; /* Reset keepalive timeout */ ssh_packet_set_alive_timeouts(ssh, 0); debug2_f("type %d id %d", type, id); if ((c = channel_lookup(ssh, id)) == NULL) { logit_f("%d: unknown", id); return 0; } if (channel_proxy_upstream(c, type, seq, ssh)) return 0; if (sshpkt_get_end(ssh) != 0) ssh_packet_disconnect(ssh, "Invalid status confirm message"); if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL) return 0; cc->cb(ssh, type, c, cc->ctx); TAILQ_REMOVE(&c->status_confirms, cc, entry); freezero(cc, sizeof(*cc)); return 0; } /* -- tcp forwarding */ void channel_set_af(struct ssh *ssh, int af) { ssh->chanctxt->IPv4or6 = af; } /* * Determine whether or not a port forward listens to loopback, the * specified address or wildcard. On the client, a specified bind * address will always override gateway_ports. On the server, a * gateway_ports of 1 (``yes'') will override the client's specification * and force a wildcard bind, whereas a value of 2 (``clientspecified'') * will bind to whatever address the client asked for. * * Special-case listen_addrs are: * * "0.0.0.0" -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR * "" (empty string), "*" -> wildcard v4/v6 * "localhost" -> loopback v4/v6 * "127.0.0.1" / "::1" -> accepted even if gateway_ports isn't set */ static const char * channel_fwd_bind_addr(struct ssh *ssh, const char *listen_addr, int *wildcardp, int is_client, struct ForwardOptions *fwd_opts) { const char *addr = NULL; int wildcard = 0; if (listen_addr == NULL) { /* No address specified: default to gateway_ports setting */ if (fwd_opts->gateway_ports) wildcard = 1; } else if (fwd_opts->gateway_ports || is_client) { if (((ssh->compat & SSH_OLD_FORWARD_ADDR) && strcmp(listen_addr, "0.0.0.0") == 0 && is_client == 0) || *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 || (!is_client && fwd_opts->gateway_ports == 1)) { wildcard = 1; /* * Notify client if they requested a specific listen * address and it was overridden. */ if (*listen_addr != '\0' && strcmp(listen_addr, "0.0.0.0") != 0 && strcmp(listen_addr, "*") != 0) { ssh_packet_send_debug(ssh, "Forwarding listen address " "\"%s\" overridden by server " "GatewayPorts", listen_addr); } } else if (strcmp(listen_addr, "localhost") != 0 || strcmp(listen_addr, "127.0.0.1") == 0 || strcmp(listen_addr, "::1") == 0) { /* * Accept explicit localhost address when * GatewayPorts=yes. The "localhost" hostname is * deliberately skipped here so it will listen on all * available local address families. */ addr = listen_addr; } } else if (strcmp(listen_addr, "127.0.0.1") == 0 || strcmp(listen_addr, "::1") == 0) { /* * If a specific IPv4/IPv6 localhost address has been * requested then accept it even if gateway_ports is in * effect. This allows the client to prefer IPv4 or IPv6. */ addr = listen_addr; } if (wildcardp != NULL) *wildcardp = wildcard; return addr; } static int channel_setup_fwd_listener_tcpip(struct ssh *ssh, int type, struct Forward *fwd, int *allocated_listen_port, struct ForwardOptions *fwd_opts) { Channel *c; int sock, r, success = 0, wildcard = 0, is_client; struct addrinfo hints, *ai, *aitop; const char *host, *addr; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; in_port_t *lport_p; is_client = (type == SSH_CHANNEL_PORT_LISTENER); if (is_client && fwd->connect_path != NULL) { host = fwd->connect_path; } else { host = (type == SSH_CHANNEL_RPORT_LISTENER) ? fwd->listen_host : fwd->connect_host; if (host == NULL) { error("No forward host name."); return 0; } if (strlen(host) >= NI_MAXHOST) { error("Forward host name too long."); return 0; } } /* Determine the bind address, cf. channel_fwd_bind_addr() comment */ addr = channel_fwd_bind_addr(ssh, fwd->listen_host, &wildcard, is_client, fwd_opts); debug3_f("type %d wildcard %d addr %s", type, wildcard, (addr == NULL) ? "NULL" : addr); /* * getaddrinfo returns a loopback address if the hostname is * set to NULL and hints.ai_flags is not AI_PASSIVE */ memset(&hints, 0, sizeof(hints)); hints.ai_family = 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_f("getaddrinfo(%.64s): %s", addr, ssh_gai_strerror(r)); } return 0; } if (allocated_listen_port != NULL) *allocated_listen_port = 0; for (ai = aitop; ai; ai = ai->ai_next) { switch (ai->ai_family) { case AF_INET: lport_p = &((struct sockaddr_in *)ai->ai_addr)-> sin_port; break; case AF_INET6: lport_p = &((struct sockaddr_in6 *)ai->ai_addr)-> sin6_port; break; default: continue; } /* * If allocating a port for -R forwards, then use the * same port for all address families. */ if (type == SSH_CHANNEL_RPORT_LISTENER && 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_f("getnameinfo failed"); continue; } /* Create a port to listen for the host. */ sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock == -1) { /* this is no error since kernel may not support ipv6 */ verbose("socket [%s]:%s: %.100s", ntop, strport, strerror(errno)); continue; } set_reuseaddr(sock); debug("Local forwarding listening on %s port %s.", ntop, strport); /* Bind the socket to the address. */ if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) { /* * address can be in if use ipv6 address is * already bound */ verbose("bind [%s]:%s: %.100s", ntop, strport, strerror(errno)); close(sock); continue; } /* Start listening for connections on the socket. */ if (listen(sock, SSH_LISTEN_BACKLOG) == -1) { error("listen [%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 && !(ssh->compat & SSH_BUG_DYNAMIC_RPORT)) c->listening_port = *allocated_listen_port; else c->listening_port = fwd->listen_port; success = 1; } if (success == 0) error_f("cannot listen to port: %d", 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_f("unexpected channel type %d", 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_f("type %d path %s", 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_f("close channel %d", 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_f("close channel %d", 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_f("close channel %d", 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_f("no path specified."); 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_f("close channel %d", i); channel_free(ssh, c); found = 1; } } return found; } int channel_cancel_lport_listener(struct ssh *ssh, struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts) { if (fwd->listen_path != NULL) { return channel_cancel_lport_listener_streamlocal(ssh, fwd->listen_path); } else { return channel_cancel_lport_listener_tcpip(ssh, fwd->listen_host, fwd->listen_port, cport, fwd_opts); } } /* protocol local port fwd, used by ssh */ int channel_setup_local_fwd_listener(struct ssh *ssh, struct Forward *fwd, struct ForwardOptions *fwd_opts) { if (fwd->listen_path != NULL) { return channel_setup_fwd_listener_streamlocal(ssh, SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts); } else { return channel_setup_fwd_listener_tcpip(ssh, SSH_CHANNEL_PORT_LISTENER, fwd, NULL, fwd_opts); } } /* Matches a remote forwarding permission against a requested forwarding */ static int remote_open_match(struct permission *allowed_open, struct Forward *fwd) { int ret; char *lhost; /* XXX add ACLs for streamlocal */ if (fwd->listen_path != NULL) return 1; if (fwd->listen_host == NULL || allowed_open->listen_host == NULL) return 0; if (allowed_open->listen_port != FWD_PERMIT_ANY_PORT && allowed_open->listen_port != fwd->listen_port) return 0; /* Match hostnames case-insensitively */ lhost = xstrdup(fwd->listen_host); lowercase(lhost); ret = match_pattern(lhost, allowed_open->listen_host); free(lhost); return ret; } /* Checks whether a requested remote forwarding is permitted */ static int check_rfwd_permission(struct ssh *ssh, struct Forward *fwd) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->remote_perms; u_int i, permit, permit_adm = 1; struct permission *perm; /* XXX apply GatewayPorts override before checking? */ permit = pset->all_permitted; if (!permit) { for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (remote_open_match(perm, fwd)) { permit = 1; break; } } } if (pset->num_permitted_admin > 0) { permit_adm = 0; for (i = 0; i < pset->num_permitted_admin; i++) { perm = &pset->permitted_admin[i]; if (remote_open_match(perm, fwd)) { permit_adm = 1; break; } } } return permit && permit_adm; } /* protocol v2 remote port fwd, used by sshd */ int channel_setup_remote_fwd_listener(struct ssh *ssh, struct Forward *fwd, int *allocated_listen_port, struct ForwardOptions *fwd_opts) { if (!check_rfwd_permission(ssh, fwd)) { ssh_packet_send_debug(ssh, "port forwarding refused"); if (fwd->listen_path != NULL) /* XXX always allowed, see remote_open_match() */ logit("Received request from %.100s port %d to " "remote forward to path \"%.100s\", " "but the request was denied.", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), fwd->listen_path); else if(fwd->listen_host != NULL) logit("Received request from %.100s port %d to " "remote forward to host %.100s port %d, " "but the request was denied.", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), fwd->listen_host, fwd->listen_port ); else logit("Received request from %.100s port %d to remote " "forward, but the request was denied.", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); return 0; } if (fwd->listen_path != NULL) { return channel_setup_fwd_listener_streamlocal(ssh, SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts); } else { return channel_setup_fwd_listener_tcpip(ssh, SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port, fwd_opts); } } /* * Translate the requested rfwd listen host to something usable for * this server. */ static const char * channel_rfwd_bind_host(const char *listen_host) { if (listen_host == NULL) { return "localhost"; } else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) { return ""; } else return listen_host; } /* * Initiate forwarding of connections to port "port" on remote host through * the secure channel to host:port from local side. * Returns handle (index) for updating the dynamic listen port with * channel_update_permission(). */ int channel_request_remote_forwarding(struct ssh *ssh, struct Forward *fwd) { int r, success = 0, idx = -1; const 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_fr(r, "request streamlocal"); } 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_fr(r, "request tcpip-forward"); } /* 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 = fwd->connect_path; port_to_connect = PORT_STREAMLOCAL; } else { host_to_connect = fwd->connect_host; port_to_connect = fwd->connect_port; } if (fwd->listen_path != NULL) { listen_path = fwd->listen_path; listen_port = PORT_STREAMLOCAL; } else { listen_host = fwd->listen_host; listen_port = fwd->listen_port; } idx = permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, host_to_connect, port_to_connect, listen_host, listen_path, listen_port, NULL); } return idx; } static int open_match(struct permission *allowed_open, const char *requestedhost, int requestedport) { if (allowed_open->host_to_connect == NULL) return 0; if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT && allowed_open->port_to_connect != requestedport) return 0; if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 && strcmp(allowed_open->host_to_connect, requestedhost) != 0) return 0; return 1; } /* * Note that in the listen host/port case * we don't support FWD_PERMIT_ANY_PORT and * need to translate between the configured-host (listen_host) * and what we've sent to the remote server (channel_rfwd_bind_host) */ static int open_listen_match_tcpip(struct permission *allowed_open, const char *requestedhost, u_short requestedport, int translate) { const char *allowed_host; if (allowed_open->host_to_connect == NULL) return 0; if (allowed_open->listen_port != requestedport) return 0; if (!translate && allowed_open->listen_host == NULL && requestedhost == NULL) return 1; allowed_host = translate ? channel_rfwd_bind_host(allowed_open->listen_host) : allowed_open->listen_host; if (allowed_host == NULL || requestedhost == NULL || strcmp(allowed_host, requestedhost) != 0) return 0; return 1; } static int open_listen_match_streamlocal(struct permission *allowed_open, const char *requestedpath) { if (allowed_open->host_to_connect == NULL) return 0; if (allowed_open->listen_port != PORT_STREAMLOCAL) return 0; if (allowed_open->listen_path == NULL || strcmp(allowed_open->listen_path, requestedpath) != 0) return 0; return 1; } /* * Request cancellation of remote forwarding of connection host:port from * local side. */ static int channel_request_rforward_cancel_tcpip(struct ssh *ssh, const char *host, u_short port) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; int r; u_int i; struct permission *perm = NULL; for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_listen_match_tcpip(perm, host, port, 0)) break; perm = NULL; } if (perm == NULL) { debug_f("requested forward not found"); 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_fr(r, "send cancel"); fwd_perm_clear(perm); /* unregister */ return 0; } /* * Request cancellation of remote forwarding of Unix domain socket * path from local side. */ static int channel_request_rforward_cancel_streamlocal(struct ssh *ssh, const char *path) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; int r; u_int i; struct permission *perm = NULL; for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_listen_match_streamlocal(perm, path)) break; perm = NULL; } if (perm == NULL) { debug_f("requested forward not found"); 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_fr(r, "send cancel"); 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_f("index out of range: %d num_permitted_user %d", 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 = (ssh->compat & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport; } } /* 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_f("getnameinfo failed"); continue; } break; default: continue; } debug_f("start for host %.100s ([%.100s]:%s)", cctx->host, ntop, strport); 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_f("set_nonblock(%d)", sock); if (connect(sock, cctx->ai->ai_addr, cctx->ai->ai_addrlen) == -1 && errno != EINPROGRESS) { debug_f("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_f("connect host %.100s ([%.100s]:%s) in progress, fd=%d", cctx->host, ntop, strport, sock); cctx->ai = cctx->ai->ai_next; return sock; } return -1; } static void channel_connect_ctx_free(struct channel_connect *cctx) { free(cctx->host); if (cctx->aitop) { if (cctx->aitop->ai_family == AF_UNIX) free(cctx->aitop); else freeaddrinfo(cctx->aitop); } memset(cctx, 0, sizeof(*cctx)); } /* * Return connecting socket to remote host:port or local socket path, * passing back the failure reason if appropriate. */ static int connect_to_helper(struct ssh *ssh, const char *name, int port, int socktype, char *ctype, char *rname, struct channel_connect *cctx, int *reason, const char **errmsg) { struct addrinfo hints; int gaierr; int sock = -1; char strport[NI_MAXSERV]; if (port == PORT_STREAMLOCAL) { struct sockaddr_un *sunaddr; struct addrinfo *ai; if (strlen(name) > sizeof(sunaddr->sun_path)) { error("%.100s: %.100s", name, strerror(ENAMETOOLONG)); return -1; } /* * Fake up a struct addrinfo for AF_UNIX connections. * channel_connect_ctx_free() must check ai_family * and use free() not freeaddirinfo() for AF_UNIX. */ ai = xmalloc(sizeof(*ai) + sizeof(*sunaddr)); memset(ai, 0, sizeof(*ai) + sizeof(*sunaddr)); ai->ai_addr = (struct sockaddr *)(ai + 1); ai->ai_addrlen = sizeof(*sunaddr); ai->ai_family = AF_UNIX; ai->ai_socktype = socktype; ai->ai_protocol = PF_UNSPEC; sunaddr = (struct sockaddr_un *)ai->ai_addr; sunaddr->sun_family = AF_UNIX; strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path)); cctx->aitop = ai; } else { memset(&hints, 0, sizeof(hints)); hints.ai_family = ssh->chanctxt->IPv4or6; hints.ai_socktype = socktype; snprintf(strport, sizeof strport, "%d", port); if ((gaierr = getaddrinfo(name, strport, &hints, &cctx->aitop)) != 0) { if (errmsg != NULL) *errmsg = ssh_gai_strerror(gaierr); if (reason != NULL) *reason = SSH2_OPEN_CONNECT_FAILED; error("connect_to %.100s: unknown host (%s)", name, ssh_gai_strerror(gaierr)); return -1; } } cctx->host = xstrdup(name); cctx->port = port; cctx->ai = cctx->aitop; if ((sock = connect_next(cctx)) == -1) { error("connect to %.100s port %d failed: %s", name, port, strerror(errno)); return -1; } return sock; } /* Return CONNECTING channel to remote host:port or local socket path */ static Channel * connect_to(struct ssh *ssh, const char *host, int port, char *ctype, char *rname) { struct channel_connect cctx; Channel *c; int sock; memset(&cctx, 0, sizeof(cctx)); sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname, &cctx, NULL, NULL); if (sock == -1) { channel_connect_ctx_free(&cctx); return NULL; } c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1); c->host_port = port; c->path = xstrdup(host); c->connect_ctx = cctx; return c; } /* * returns either the newly connected channel or the downstream channel * that needs to deal with this connection. */ Channel * channel_connect_by_listen_address(struct ssh *ssh, const char *listen_host, u_short listen_port, char *ctype, char *rname) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; u_int i; struct permission *perm; for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_listen_match_tcpip(perm, listen_host, listen_port, 1)) { if (perm->downstream) return perm->downstream; if (perm->port_to_connect == 0) return rdynamic_connect_prepare(ssh, ctype, rname); return connect_to(ssh, perm->host_to_connect, perm->port_to_connect, ctype, rname); } } error("WARNING: Server requests forwarding for unknown listen_port %d", listen_port); return NULL; } Channel * channel_connect_by_listen_path(struct ssh *ssh, const char *path, char *ctype, char *rname) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; u_int i; struct permission *perm; for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_listen_match_streamlocal(perm, path)) { return connect_to(ssh, perm->host_to_connect, perm->port_to_connect, ctype, rname); } } error("WARNING: Server requests forwarding for unknown path %.100s", path); return NULL; } /* Check if connecting to that port is permitted and connect. */ Channel * channel_connect_to_port(struct ssh *ssh, const char *host, u_short port, char *ctype, char *rname, int *reason, const char **errmsg) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; struct channel_connect cctx; Channel *c; u_int i, permit, permit_adm = 1; int sock; struct permission *perm; permit = pset->all_permitted; if (!permit) { for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_match(perm, host, port)) { permit = 1; break; } } } if (pset->num_permitted_admin > 0) { permit_adm = 0; for (i = 0; i < pset->num_permitted_admin; i++) { perm = &pset->permitted_admin[i]; if (open_match(perm, host, port)) { permit_adm = 1; break; } } } if (!permit || !permit_adm) { logit("Received request from %.100s port %d to connect to " "host %.100s port %d, but the request was denied.", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), host, port); if (reason != NULL) *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; return NULL; } memset(&cctx, 0, sizeof(cctx)); sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname, &cctx, reason, errmsg); if (sock == -1) { channel_connect_ctx_free(&cctx); return NULL; } c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1); c->host_port = port; c->path = xstrdup(host); c->connect_ctx = cctx; return c; } /* Check if connecting to that path is permitted and connect. */ Channel * channel_connect_to_path(struct ssh *ssh, const char *path, char *ctype, char *rname) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; u_int i, permit, permit_adm = 1; struct permission *perm; permit = pset->all_permitted; if (!permit) { for (i = 0; i < pset->num_permitted_user; i++) { perm = &pset->permitted_user[i]; if (open_match(perm, path, PORT_STREAMLOCAL)) { permit = 1; break; } } } if (pset->num_permitted_admin > 0) { permit_adm = 0; for (i = 0; i < pset->num_permitted_admin; i++) { perm = &pset->permitted_admin[i]; if (open_match(perm, path, PORT_STREAMLOCAL)) { permit_adm = 1; break; } } } if (!permit || !permit_adm) { logit("Received request to connect to path %.100s, " "but the request was denied.", path); return NULL; } return connect_to(ssh, path, PORT_STREAMLOCAL, ctype, rname); } void channel_send_window_changes(struct ssh *ssh) { struct ssh_channels *sc = ssh->chanctxt; struct winsize ws; int r; u_int i; for (i = 0; i < sc->channels_alloc; i++) { if (sc->channels[i] == NULL || !sc->channels[i]->client_tty || sc->channels[i]->type != SSH_CHANNEL_OPEN) continue; if (ioctl(sc->channels[i]->rfd, TIOCGWINSZ, &ws) == -1) continue; channel_request_start(ssh, i, "window-change", 0); if ((r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 || (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 || (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 || (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0 || (r = sshpkt_send(ssh)) != 0) fatal_fr(r, "channel %u; send window-change", i); } } /* 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_fr(r, "channel %i; confirm", c->self); return c; } /* Return CONNECTING socket to remote host:port or local socket path */ static int rdynamic_connect_finish(struct ssh *ssh, Channel *c) { struct ssh_channels *sc = ssh->chanctxt; struct permission_set *pset = &sc->local_perms; struct permission *perm; struct channel_connect cctx; u_int i, permit_adm = 1; int sock; 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, c->path, c->host_port)) { permit_adm = 1; break; } } } if (!permit_adm) { debug_f("requested forward not permitted"); return -1; } memset(&cctx, 0, sizeof(cctx)); sock = connect_to_helper(ssh, c->path, c->host_port, SOCK_STREAM, NULL, NULL, &cctx, NULL, NULL); if (sock == -1) channel_connect_ctx_free(&cctx); else { /* similar to SSH_CHANNEL_CONNECTING but we've already sent the open */ c->type = SSH_CHANNEL_RDYNAMIC_FINISH; c->connect_ctx = cctx; channel_register_fds(ssh, c, sock, sock, -1, 0, 1, 0); } return sock; } /* -- X11 forwarding */ /* * Creates an internet domain socket for listening for X11 connections. * Returns 0 and a suitable display number for the DISPLAY variable * stored in display_numberp , or -1 if an error occurs. */ int x11_create_display_inet(struct ssh *ssh, int x11_display_offset, int x11_use_localhost, int single_connection, u_int *display_numberp, int **chanids) { Channel *nc = NULL; int display_number, sock; u_short port; struct addrinfo hints, *ai, *aitop; char strport[NI_MAXSERV]; int gaierr, n, num_socks = 0, socks[NUM_SOCKS]; if (chanids == NULL) return -1; for (display_number = x11_display_offset; display_number < MAX_DISPLAYS; display_number++) { port = 6000 + display_number; memset(&hints, 0, sizeof(hints)); hints.ai_family = ssh->chanctxt->IPv4or6; hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%d", port); if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) { error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr)); return -1; } for (ai = aitop; ai; ai = ai->ai_next) { if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) continue; sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock == -1) { error("socket: %.100s", strerror(errno)); freeaddrinfo(aitop); return -1; } set_reuseaddr(sock); if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) { debug2_f("bind port %d: %.100s", port, strerror(errno)); close(sock); for (n = 0; n < num_socks; n++) close(socks[n]); num_socks = 0; break; } socks[num_socks++] = sock; if (num_socks == NUM_SOCKS) break; } freeaddrinfo(aitop); if (num_socks > 0) break; } if (display_number >= MAX_DISPLAYS) { error("Failed to allocate internet-domain X11 display socket."); return -1; } /* Start listening for connections on the socket. */ for (n = 0; n < num_socks; n++) { sock = socks[n]; if (listen(sock, SSH_LISTEN_BACKLOG) == -1) { error("listen: %.100s", strerror(errno)); close(sock); return -1; } } /* Allocate a channel for each socket. */ *chanids = xcalloc(num_socks + 1, sizeof(**chanids)); for (n = 0; n < num_socks; n++) { sock = socks[n]; nc = channel_new(ssh, "x11-listener", SSH_CHANNEL_X11_LISTENER, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "X11 inet listener", 1); nc->single_connection = single_connection; (*chanids)[n] = nc->self; } (*chanids)[n] = -1; /* Return the display number for the DISPLAY environment variable. */ *display_numberp = display_number; return 0; } static int connect_local_xsocket(u_int dnr) { int sock; struct sockaddr_un addr; sock = socket(AF_UNIX, SOCK_STREAM, 0); if (sock == -1) error("socket: %.100s", strerror(errno)); memset(&addr, 0, sizeof(addr)); addr.sun_family = AF_UNIX; snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr); if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) return sock; close(sock); error("connect %.100s: %.100s", addr.sun_path, strerror(errno)); return -1; } int x11_connect_display(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. */ /* * Check if it is a unix domain socket. Unix domain displays are in * one of the following formats: unix:d[.s], :d[.s], ::d[.s] */ if (strncmp(display, "unix:", 5) == 0 || display[0] == ':') { /* Connect to the unix domain socket. */ if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) { error("Could not parse display number from DISPLAY: " "%.100s", display); return -1; } /* Create a socket. */ sock = connect_local_xsocket(display_number); if (sock < 0) return -1; /* OK, we now have a connection to the display. */ return sock; } /* * Connect to an inet socket. The DISPLAY value is supposedly * hostname:d[.s], where hostname may also be numeric IP address. */ strlcpy(buf, display, sizeof(buf)); cp = strchr(buf, ':'); if (!cp) { error("Could not find ':' in DISPLAY: %.100s", display); return -1; } *cp = 0; /* * buf now contains the host name. But first we parse the * display number. */ if (sscanf(cp + 1, "%u", &display_number) != 1) { error("Could not parse display number from DISPLAY: %.100s", display); return -1; } /* Look up the host address */ memset(&hints, 0, sizeof(hints)); hints.ai_family = ssh->chanctxt->IPv4or6; hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%u", 6000 + display_number); if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) { error("%.100s: unknown host. (%s)", buf, ssh_gai_strerror(gaierr)); return -1; } for (ai = aitop; ai; ai = ai->ai_next) { /* Create a socket. */ sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock == -1) { debug2("socket: %.100s", strerror(errno)); continue; } /* Connect it to the display. */ if (connect(sock, ai->ai_addr, ai->ai_addrlen) == -1) { debug2("connect %.100s port %u: %.100s", buf, 6000 + display_number, strerror(errno)); close(sock); continue; } /* Success */ break; } freeaddrinfo(aitop); if (!ai) { error("connect %.100s port %u: %.100s", buf, 6000 + display_number, strerror(errno)); return -1; } set_nodelay(sock); return sock; } /* * Requests forwarding of X11 connections, generates fake authentication * data, and enables authentication spoofing. * This should be called in the client only. */ void x11_request_forwarding_with_spoofing(struct ssh *ssh, int client_session_id, const char *disp, const char *proto, const char *data, int want_reply) { struct ssh_channels *sc = ssh->chanctxt; u_int data_len = (u_int) strlen(data) / 2; u_int i, value; const char *cp; char *new_data; int r, screen_number; if (sc->x11_saved_display == NULL) sc->x11_saved_display = xstrdup(disp); else if (strcmp(disp, sc->x11_saved_display) != 0) { error("x11_request_forwarding_with_spoofing: different " "$DISPLAY already forwarded"); return; } cp = strchr(disp, ':'); if (cp) cp = strchr(cp, '.'); if (cp) screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL); else screen_number = 0; if (sc->x11_saved_proto == NULL) { /* Save protocol name. */ sc->x11_saved_proto = xstrdup(proto); /* Extract real authentication data. */ sc->x11_saved_data = xmalloc(data_len); for (i = 0; i < data_len; i++) { if (sscanf(data + 2 * i, "%2x", &value) != 1) { fatal("x11_request_forwarding: bad " "authentication data: %.100s", data); } sc->x11_saved_data[i] = value; } sc->x11_saved_data_len = data_len; /* Generate fake data of the same length. */ sc->x11_fake_data = xmalloc(data_len); arc4random_buf(sc->x11_fake_data, data_len); sc->x11_fake_data_len = data_len; } /* Convert the fake data into hex. */ new_data = tohex(sc->x11_fake_data, data_len); /* Send the request packet. */ channel_request_start(ssh, client_session_id, "x11-req", want_reply); if ((r = sshpkt_put_u8(ssh, 0)) != 0 || /* bool: single connection */ (r = sshpkt_put_cstring(ssh, proto)) != 0 || (r = sshpkt_put_cstring(ssh, new_data)) != 0 || (r = sshpkt_put_u32(ssh, screen_number)) != 0 || (r = sshpkt_send(ssh)) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) fatal_fr(r, "send x11-req"); free(new_data); } /* * Returns whether an x11 channel was used recently (less than a second ago) */ int x11_channel_used_recently(struct ssh *ssh) { u_int i; Channel *c; time_t lastused = 0; for (i = 0; i < ssh->chanctxt->channels_alloc; i++) { c = ssh->chanctxt->channels[i]; if (c == NULL || c->ctype == NULL || c->lastused == 0 || strcmp(c->ctype, "x11-connection") != 0) continue; lastused = c->lastused; } return lastused != 0 && monotime() > lastused + 1; }