/* $OpenBSD: mux.c,v 1.69 2017/09/20 05:19:00 dtucker Exp $ */ /* * Copyright (c) 2002-2008 Damien Miller * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* ssh session multiplexing support */ /* * TODO: * - Better signalling from master to slave, especially passing of * error messages * - Better fall-back from mux slave error to new connection. * - ExitOnForwardingFailure * - Maybe extension mechanisms for multi-X11/multi-agent forwarding * - Support ~^Z in mux slaves. * - Inspect or control sessions in master. * - If we ever support the "signal" channel request, send signals on * sessions in master. */ #include "includes.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef HAVE_PATHS_H #include #endif #ifdef HAVE_POLL_H #include #else # ifdef HAVE_SYS_POLL_H # include # endif #endif #ifdef HAVE_UTIL_H # include #endif #include "openbsd-compat/sys-queue.h" #include "xmalloc.h" #include "log.h" #include "ssh.h" #include "ssh2.h" #include "pathnames.h" #include "misc.h" #include "match.h" #include "buffer.h" #include "channels.h" #include "msg.h" #include "packet.h" #include "monitor_fdpass.h" #include "sshpty.h" #include "key.h" #include "readconf.h" #include "clientloop.h" #include "ssherr.h" /* from ssh.c */ extern int tty_flag; extern Options options; extern int stdin_null_flag; extern char *host; extern int subsystem_flag; extern Buffer command; extern volatile sig_atomic_t quit_pending; /* Context for session open confirmation callback */ struct mux_session_confirm_ctx { u_int want_tty; u_int want_subsys; u_int want_x_fwd; u_int want_agent_fwd; Buffer cmd; char *term; struct termios tio; char **env; u_int rid; }; /* Context for stdio fwd open confirmation callback */ struct mux_stdio_confirm_ctx { u_int rid; }; /* Context for global channel callback */ struct mux_channel_confirm_ctx { u_int cid; /* channel id */ u_int rid; /* request id */ int fid; /* forward id */ }; /* fd to control socket */ int muxserver_sock = -1; /* client request id */ u_int muxclient_request_id = 0; /* Multiplexing control command */ u_int muxclient_command = 0; /* Set when signalled. */ static volatile sig_atomic_t muxclient_terminate = 0; /* PID of multiplex server */ static u_int muxserver_pid = 0; static Channel *mux_listener_channel = NULL; struct mux_master_state { int hello_rcvd; }; /* mux protocol messages */ #define MUX_MSG_HELLO 0x00000001 #define MUX_C_NEW_SESSION 0x10000002 #define MUX_C_ALIVE_CHECK 0x10000004 #define MUX_C_TERMINATE 0x10000005 #define MUX_C_OPEN_FWD 0x10000006 #define MUX_C_CLOSE_FWD 0x10000007 #define MUX_C_NEW_STDIO_FWD 0x10000008 #define MUX_C_STOP_LISTENING 0x10000009 #define MUX_C_PROXY 0x1000000f #define MUX_S_OK 0x80000001 #define MUX_S_PERMISSION_DENIED 0x80000002 #define MUX_S_FAILURE 0x80000003 #define MUX_S_EXIT_MESSAGE 0x80000004 #define MUX_S_ALIVE 0x80000005 #define MUX_S_SESSION_OPENED 0x80000006 #define MUX_S_REMOTE_PORT 0x80000007 #define MUX_S_TTY_ALLOC_FAIL 0x80000008 #define MUX_S_PROXY 0x8000000f /* type codes for MUX_C_OPEN_FWD and MUX_C_CLOSE_FWD */ #define MUX_FWD_LOCAL 1 #define MUX_FWD_REMOTE 2 #define MUX_FWD_DYNAMIC 3 static void mux_session_confirm(struct ssh *, int, int, void *); static void mux_stdio_confirm(struct ssh *, int, int, void *); static int process_mux_master_hello(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_new_session(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_alive_check(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_terminate(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_open_fwd(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_close_fwd(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_stdio_fwd(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_stop_listening(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static int process_mux_proxy(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); static const struct { u_int type; int (*handler)(struct ssh *, u_int, Channel *, struct sshbuf *, struct sshbuf *); } mux_master_handlers[] = { { MUX_MSG_HELLO, process_mux_master_hello }, { MUX_C_NEW_SESSION, process_mux_new_session }, { MUX_C_ALIVE_CHECK, process_mux_alive_check }, { MUX_C_TERMINATE, process_mux_terminate }, { MUX_C_OPEN_FWD, process_mux_open_fwd }, { MUX_C_CLOSE_FWD, process_mux_close_fwd }, { MUX_C_NEW_STDIO_FWD, process_mux_stdio_fwd }, { MUX_C_STOP_LISTENING, process_mux_stop_listening }, { MUX_C_PROXY, process_mux_proxy }, { 0, NULL } }; /* Cleanup callback fired on closure of mux slave _session_ channel */ /* ARGSUSED */ static void mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused) { Channel *cc, *c = channel_by_id(ssh, cid); debug3("%s: entering for channel %d", __func__, cid); if (c == NULL) fatal("%s: channel_by_id(%i) == NULL", __func__, cid); if (c->ctl_chan != -1) { if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) fatal("%s: channel %d missing control channel %d", __func__, c->self, c->ctl_chan); c->ctl_chan = -1; cc->remote_id = 0; cc->have_remote_id = 0; chan_rcvd_oclose(ssh, cc); } channel_cancel_cleanup(ssh, c->self); } /* Cleanup callback fired on closure of mux slave _control_ channel */ /* ARGSUSED */ static void mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused) { Channel *sc, *c = channel_by_id(ssh, cid); debug3("%s: entering for channel %d", __func__, cid); if (c == NULL) fatal("%s: channel_by_id(%i) == NULL", __func__, cid); if (c->have_remote_id) { if ((sc = channel_by_id(ssh, c->remote_id)) == NULL) fatal("%s: channel %d missing session channel %u", __func__, c->self, c->remote_id); c->remote_id = 0; c->have_remote_id = 0; sc->ctl_chan = -1; if (sc->type != SSH_CHANNEL_OPEN && sc->type != SSH_CHANNEL_OPENING) { debug2("%s: channel %d: not open", __func__, sc->self); chan_mark_dead(ssh, sc); } else { if (sc->istate == CHAN_INPUT_OPEN) chan_read_failed(ssh, sc); if (sc->ostate == CHAN_OUTPUT_OPEN) chan_write_failed(ssh, sc); } } channel_cancel_cleanup(ssh, c->self); } /* Check mux client environment variables before passing them to mux master. */ static int env_permitted(char *env) { int i, ret; char name[1024], *cp; if ((cp = strchr(env, '=')) == NULL || cp == env) return 0; ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env); if (ret <= 0 || (size_t)ret >= sizeof(name)) { error("env_permitted: name '%.100s...' too long", env); return 0; } for (i = 0; i < options.num_send_env; i++) if (match_pattern(name, options.send_env[i])) return 1; return 0; } /* Mux master protocol message handlers */ static int process_mux_master_hello(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { u_int ver; struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; if (state == NULL) fatal("%s: channel %d: c->mux_ctx == NULL", __func__, c->self); if (state->hello_rcvd) { error("%s: HELLO received twice", __func__); return -1; } if (buffer_get_int_ret(&ver, m) != 0) { malf: error("%s: malformed message", __func__); return -1; } if (ver != SSHMUX_VER) { error("Unsupported multiplexing protocol version %d " "(expected %d)", ver, SSHMUX_VER); return -1; } debug2("%s: channel %d slave version %u", __func__, c->self, ver); /* No extensions are presently defined */ while (buffer_len(m) > 0) { char *name = buffer_get_string_ret(m, NULL); char *value = buffer_get_string_ret(m, NULL); if (name == NULL || value == NULL) { free(name); free(value); goto malf; } debug2("Unrecognised slave extension \"%s\"", name); free(name); free(value); } state->hello_rcvd = 1; return 0; } static int process_mux_new_session(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { Channel *nc; struct mux_session_confirm_ctx *cctx; char *reserved, *cmd, *cp; u_int i, j, len, env_len, escape_char, window, packetmax; int new_fd[3]; /* Reply for SSHMUX_COMMAND_OPEN */ cctx = xcalloc(1, sizeof(*cctx)); cctx->term = NULL; cctx->rid = rid; cmd = reserved = NULL; cctx->env = NULL; env_len = 0; if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&cctx->want_tty, m) != 0 || buffer_get_int_ret(&cctx->want_x_fwd, m) != 0 || buffer_get_int_ret(&cctx->want_agent_fwd, m) != 0 || buffer_get_int_ret(&cctx->want_subsys, m) != 0 || buffer_get_int_ret(&escape_char, m) != 0 || (cctx->term = buffer_get_string_ret(m, &len)) == NULL || (cmd = buffer_get_string_ret(m, &len)) == NULL) { malf: free(cmd); free(reserved); for (j = 0; j < env_len; j++) free(cctx->env[j]); free(cctx->env); free(cctx->term); free(cctx); error("%s: malformed message", __func__); return -1; } free(reserved); reserved = NULL; while (buffer_len(m) > 0) { #define MUX_MAX_ENV_VARS 4096 if ((cp = buffer_get_string_ret(m, &len)) == NULL) goto malf; if (!env_permitted(cp)) { free(cp); continue; } cctx->env = xreallocarray(cctx->env, env_len + 2, sizeof(*cctx->env)); cctx->env[env_len++] = cp; cctx->env[env_len] = NULL; if (env_len > MUX_MAX_ENV_VARS) { error(">%d environment variables received, ignoring " "additional", MUX_MAX_ENV_VARS); break; } } debug2("%s: channel %d: request tty %d, X %d, agent %d, subsys %d, " "term \"%s\", cmd \"%s\", env %u", __func__, c->self, cctx->want_tty, cctx->want_x_fwd, cctx->want_agent_fwd, cctx->want_subsys, cctx->term, cmd, env_len); buffer_init(&cctx->cmd); buffer_append(&cctx->cmd, cmd, strlen(cmd)); free(cmd); cmd = NULL; /* Gather fds from client */ for(i = 0; i < 3; i++) { if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { error("%s: failed to receive fd %d from slave", __func__, i); for (j = 0; j < i; j++) close(new_fd[j]); for (j = 0; j < env_len; j++) free(cctx->env[j]); free(cctx->env); free(cctx->term); buffer_free(&cctx->cmd); free(cctx); /* prepare reply */ buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "did not receive file descriptors"); return -1; } } debug3("%s: got fds stdin %d, stdout %d, stderr %d", __func__, new_fd[0], new_fd[1], new_fd[2]); /* XXX support multiple child sessions in future */ if (c->have_remote_id) { debug2("%s: session already open", __func__); /* prepare reply */ buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "Multiple sessions not supported"); cleanup: close(new_fd[0]); close(new_fd[1]); close(new_fd[2]); free(cctx->term); if (env_len != 0) { for (i = 0; i < env_len; i++) free(cctx->env[i]); free(cctx->env); } buffer_free(&cctx->cmd); free(cctx); return 0; } if (options.control_master == SSHCTL_MASTER_ASK || options.control_master == SSHCTL_MASTER_AUTO_ASK) { if (!ask_permission("Allow shared connection to %s? ", host)) { debug2("%s: session refused by user", __func__); /* prepare reply */ buffer_put_int(r, MUX_S_PERMISSION_DENIED); buffer_put_int(r, rid); buffer_put_cstring(r, "Permission denied"); goto cleanup; } } /* Try to pick up ttymodes from client before it goes raw */ if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1) error("%s: tcgetattr: %s", __func__, strerror(errno)); /* enable nonblocking unless tty */ if (!isatty(new_fd[0])) set_nonblock(new_fd[0]); if (!isatty(new_fd[1])) set_nonblock(new_fd[1]); if (!isatty(new_fd[2])) set_nonblock(new_fd[2]); window = CHAN_SES_WINDOW_DEFAULT; packetmax = CHAN_SES_PACKET_DEFAULT; if (cctx->want_tty) { window >>= 1; packetmax >>= 1; } nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING, new_fd[0], new_fd[1], new_fd[2], window, packetmax, CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); nc->ctl_chan = c->self; /* link session -> control channel */ c->remote_id = nc->self; /* link control -> session channel */ c->have_remote_id = 1; if (cctx->want_tty && escape_char != 0xffffffff) { channel_register_filter(ssh, nc->self, client_simple_escape_filter, NULL, client_filter_cleanup, client_new_escape_filter_ctx((int)escape_char)); } debug2("%s: channel_new: %d linked to control channel %d", __func__, nc->self, nc->ctl_chan); channel_send_open(ssh, nc->self); channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx); c->mux_pause = 1; /* stop handling messages until open_confirm done */ channel_register_cleanup(ssh, nc->self, mux_master_session_cleanup_cb, 1); /* reply is deferred, sent by mux_session_confirm */ return 0; } static int process_mux_alive_check(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { debug2("%s: channel %d: alive check", __func__, c->self); /* prepare reply */ buffer_put_int(r, MUX_S_ALIVE); buffer_put_int(r, rid); buffer_put_int(r, (u_int)getpid()); return 0; } static int process_mux_terminate(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { debug2("%s: channel %d: terminate request", __func__, c->self); if (options.control_master == SSHCTL_MASTER_ASK || options.control_master == SSHCTL_MASTER_AUTO_ASK) { if (!ask_permission("Terminate shared connection to %s? ", host)) { debug2("%s: termination refused by user", __func__); buffer_put_int(r, MUX_S_PERMISSION_DENIED); buffer_put_int(r, rid); buffer_put_cstring(r, "Permission denied"); return 0; } } quit_pending = 1; buffer_put_int(r, MUX_S_OK); buffer_put_int(r, rid); /* XXX exit happens too soon - message never makes it to client */ return 0; } static char * format_forward(u_int ftype, struct Forward *fwd) { char *ret; switch (ftype) { case MUX_FWD_LOCAL: xasprintf(&ret, "local forward %.200s:%d -> %.200s:%d", (fwd->listen_path != NULL) ? fwd->listen_path : (fwd->listen_host == NULL) ? (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : fwd->listen_host, fwd->listen_port, (fwd->connect_path != NULL) ? fwd->connect_path : fwd->connect_host, fwd->connect_port); break; case MUX_FWD_DYNAMIC: xasprintf(&ret, "dynamic forward %.200s:%d -> *", (fwd->listen_host == NULL) ? (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") : fwd->listen_host, fwd->listen_port); break; case MUX_FWD_REMOTE: xasprintf(&ret, "remote forward %.200s:%d -> %.200s:%d", (fwd->listen_path != NULL) ? fwd->listen_path : (fwd->listen_host == NULL) ? "LOCALHOST" : fwd->listen_host, fwd->listen_port, (fwd->connect_path != NULL) ? fwd->connect_path : fwd->connect_host, fwd->connect_port); break; default: fatal("%s: unknown forward type %u", __func__, ftype); } return ret; } static int compare_host(const char *a, const char *b) { if (a == NULL && b == NULL) return 1; if (a == NULL || b == NULL) return 0; return strcmp(a, b) == 0; } static int compare_forward(struct Forward *a, struct Forward *b) { if (!compare_host(a->listen_host, b->listen_host)) return 0; if (!compare_host(a->listen_path, b->listen_path)) return 0; if (a->listen_port != b->listen_port) return 0; if (!compare_host(a->connect_host, b->connect_host)) return 0; if (!compare_host(a->connect_path, b->connect_path)) return 0; if (a->connect_port != b->connect_port) return 0; return 1; } static void mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt) { struct mux_channel_confirm_ctx *fctx = ctxt; char *failmsg = NULL; struct Forward *rfwd; Channel *c; Buffer out; if ((c = channel_by_id(ssh, fctx->cid)) == NULL) { /* no channel for reply */ error("%s: unknown channel", __func__); return; } buffer_init(&out); if (fctx->fid >= options.num_remote_forwards || (options.remote_forwards[fctx->fid].connect_path == NULL && options.remote_forwards[fctx->fid].connect_host == NULL)) { xasprintf(&failmsg, "unknown forwarding id %d", fctx->fid); goto fail; } rfwd = &options.remote_forwards[fctx->fid]; debug("%s: %s for: listen %d, connect %s:%d", __func__, type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : rfwd->connect_host, rfwd->connect_port); if (type == SSH2_MSG_REQUEST_SUCCESS) { if (rfwd->listen_port == 0) { rfwd->allocated_port = packet_get_int(); debug("Allocated port %u for mux remote forward" " to %s:%d", rfwd->allocated_port, rfwd->connect_host, rfwd->connect_port); buffer_put_int(&out, MUX_S_REMOTE_PORT); buffer_put_int(&out, fctx->rid); buffer_put_int(&out, rfwd->allocated_port); channel_update_permitted_opens(ssh, rfwd->handle, rfwd->allocated_port); } else { buffer_put_int(&out, MUX_S_OK); buffer_put_int(&out, fctx->rid); } goto out; } else { if (rfwd->listen_port == 0) channel_update_permitted_opens(ssh, rfwd->handle, -1); if (rfwd->listen_path != NULL) xasprintf(&failmsg, "remote port forwarding failed for " "listen path %s", rfwd->listen_path); else xasprintf(&failmsg, "remote port forwarding failed for " "listen port %d", rfwd->listen_port); debug2("%s: clearing registered forwarding for listen %d, " "connect %s:%d", __func__, rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path : rfwd->connect_host, rfwd->connect_port); free(rfwd->listen_host); free(rfwd->listen_path); free(rfwd->connect_host); free(rfwd->connect_path); memset(rfwd, 0, sizeof(*rfwd)); } fail: error("%s: %s", __func__, failmsg); buffer_put_int(&out, MUX_S_FAILURE); buffer_put_int(&out, fctx->rid); buffer_put_cstring(&out, failmsg); free(failmsg); out: buffer_put_string(c->output, buffer_ptr(&out), buffer_len(&out)); buffer_free(&out); if (c->mux_pause <= 0) fatal("%s: mux_pause %d", __func__, c->mux_pause); c->mux_pause = 0; /* start processing messages again */ } static int process_mux_open_fwd(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { struct Forward fwd; char *fwd_desc = NULL; char *listen_addr, *connect_addr; u_int ftype; u_int lport, cport; int i, ret = 0, freefwd = 1; memset(&fwd, 0, sizeof(fwd)); /* XXX - lport/cport check redundant */ if (buffer_get_int_ret(&ftype, m) != 0 || (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&lport, m) != 0 || (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&cport, m) != 0 || (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { error("%s: malformed message", __func__); ret = -1; goto out; } if (*listen_addr == '\0') { free(listen_addr); listen_addr = NULL; } if (*connect_addr == '\0') { free(connect_addr); connect_addr = NULL; } memset(&fwd, 0, sizeof(fwd)); fwd.listen_port = lport; if (fwd.listen_port == PORT_STREAMLOCAL) fwd.listen_path = listen_addr; else fwd.listen_host = listen_addr; fwd.connect_port = cport; if (fwd.connect_port == PORT_STREAMLOCAL) fwd.connect_path = connect_addr; else fwd.connect_host = connect_addr; debug2("%s: channel %d: request %s", __func__, c->self, (fwd_desc = format_forward(ftype, &fwd))); if (ftype != MUX_FWD_LOCAL && ftype != MUX_FWD_REMOTE && ftype != MUX_FWD_DYNAMIC) { logit("%s: invalid forwarding type %u", __func__, ftype); invalid: free(listen_addr); free(connect_addr); buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "Invalid forwarding request"); return 0; } if (ftype == MUX_FWD_DYNAMIC && fwd.listen_path) { logit("%s: streamlocal and dynamic forwards " "are mutually exclusive", __func__); goto invalid; } if (fwd.listen_port != PORT_STREAMLOCAL && fwd.listen_port >= 65536) { logit("%s: invalid listen port %u", __func__, fwd.listen_port); goto invalid; } if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536) || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) { logit("%s: invalid connect port %u", __func__, fwd.connect_port); goto invalid; } if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) { logit("%s: missing connect host", __func__); goto invalid; } /* Skip forwards that have already been requested */ switch (ftype) { case MUX_FWD_LOCAL: case MUX_FWD_DYNAMIC: for (i = 0; i < options.num_local_forwards; i++) { if (compare_forward(&fwd, options.local_forwards + i)) { exists: debug2("%s: found existing forwarding", __func__); buffer_put_int(r, MUX_S_OK); buffer_put_int(r, rid); goto out; } } break; case MUX_FWD_REMOTE: for (i = 0; i < options.num_remote_forwards; i++) { if (compare_forward(&fwd, options.remote_forwards + i)) { if (fwd.listen_port != 0) goto exists; debug2("%s: found allocated port", __func__); buffer_put_int(r, MUX_S_REMOTE_PORT); buffer_put_int(r, rid); buffer_put_int(r, options.remote_forwards[i].allocated_port); goto out; } } break; } if (options.control_master == SSHCTL_MASTER_ASK || options.control_master == SSHCTL_MASTER_AUTO_ASK) { if (!ask_permission("Open %s on %s?", fwd_desc, host)) { debug2("%s: forwarding refused by user", __func__); buffer_put_int(r, MUX_S_PERMISSION_DENIED); buffer_put_int(r, rid); buffer_put_cstring(r, "Permission denied"); goto out; } } if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) { if (!channel_setup_local_fwd_listener(ssh, &fwd, &options.fwd_opts)) { fail: logit("slave-requested %s failed", fwd_desc); buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "Port forwarding failed"); goto out; } add_local_forward(&options, &fwd); freefwd = 0; } else { struct mux_channel_confirm_ctx *fctx; fwd.handle = channel_request_remote_forwarding(ssh, &fwd); if (fwd.handle < 0) goto fail; add_remote_forward(&options, &fwd); fctx = xcalloc(1, sizeof(*fctx)); fctx->cid = c->self; fctx->rid = rid; fctx->fid = options.num_remote_forwards - 1; client_register_global_confirm(mux_confirm_remote_forward, fctx); freefwd = 0; c->mux_pause = 1; /* wait for mux_confirm_remote_forward */ /* delayed reply in mux_confirm_remote_forward */ goto out; } buffer_put_int(r, MUX_S_OK); buffer_put_int(r, rid); out: free(fwd_desc); if (freefwd) { free(fwd.listen_host); free(fwd.listen_path); free(fwd.connect_host); free(fwd.connect_path); } return ret; } static int process_mux_close_fwd(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { struct Forward fwd, *found_fwd; char *fwd_desc = NULL; const char *error_reason = NULL; char *listen_addr = NULL, *connect_addr = NULL; u_int ftype; int i, ret = 0; u_int lport, cport; memset(&fwd, 0, sizeof(fwd)); if (buffer_get_int_ret(&ftype, m) != 0 || (listen_addr = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&lport, m) != 0 || (connect_addr = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&cport, m) != 0 || (lport != (u_int)PORT_STREAMLOCAL && lport > 65535) || (cport != (u_int)PORT_STREAMLOCAL && cport > 65535)) { error("%s: malformed message", __func__); ret = -1; goto out; } if (*listen_addr == '\0') { free(listen_addr); listen_addr = NULL; } if (*connect_addr == '\0') { free(connect_addr); connect_addr = NULL; } memset(&fwd, 0, sizeof(fwd)); fwd.listen_port = lport; if (fwd.listen_port == PORT_STREAMLOCAL) fwd.listen_path = listen_addr; else fwd.listen_host = listen_addr; fwd.connect_port = cport; if (fwd.connect_port == PORT_STREAMLOCAL) fwd.connect_path = connect_addr; else fwd.connect_host = connect_addr; debug2("%s: channel %d: request cancel %s", __func__, c->self, (fwd_desc = format_forward(ftype, &fwd))); /* make sure this has been requested */ found_fwd = NULL; switch (ftype) { case MUX_FWD_LOCAL: case MUX_FWD_DYNAMIC: for (i = 0; i < options.num_local_forwards; i++) { if (compare_forward(&fwd, options.local_forwards + i)) { found_fwd = options.local_forwards + i; break; } } break; case MUX_FWD_REMOTE: for (i = 0; i < options.num_remote_forwards; i++) { if (compare_forward(&fwd, options.remote_forwards + i)) { found_fwd = options.remote_forwards + i; break; } } break; } if (found_fwd == NULL) error_reason = "port not forwarded"; else if (ftype == MUX_FWD_REMOTE) { /* * This shouldn't fail unless we confused the host/port * between options.remote_forwards and permitted_opens. * However, for dynamic allocated listen ports we need * to use the actual listen port. */ if (channel_request_rforward_cancel(ssh, found_fwd) == -1) error_reason = "port not in permitted opens"; } else { /* local and dynamic forwards */ /* Ditto */ if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port, &options.fwd_opts) == -1) error_reason = "port not found"; } if (error_reason == NULL) { buffer_put_int(r, MUX_S_OK); buffer_put_int(r, rid); free(found_fwd->listen_host); free(found_fwd->listen_path); free(found_fwd->connect_host); free(found_fwd->connect_path); found_fwd->listen_host = found_fwd->connect_host = NULL; found_fwd->listen_path = found_fwd->connect_path = NULL; found_fwd->listen_port = found_fwd->connect_port = 0; } else { buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, error_reason); } out: free(fwd_desc); free(listen_addr); free(connect_addr); return ret; } static int process_mux_stdio_fwd(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { Channel *nc; char *reserved, *chost; u_int cport, i, j; int new_fd[2]; struct mux_stdio_confirm_ctx *cctx; chost = reserved = NULL; if ((reserved = buffer_get_string_ret(m, NULL)) == NULL || (chost = buffer_get_string_ret(m, NULL)) == NULL || buffer_get_int_ret(&cport, m) != 0) { free(reserved); free(chost); error("%s: malformed message", __func__); return -1; } free(reserved); debug2("%s: channel %d: request stdio fwd to %s:%u", __func__, c->self, chost, cport); /* Gather fds from client */ for(i = 0; i < 2; i++) { if ((new_fd[i] = mm_receive_fd(c->sock)) == -1) { error("%s: failed to receive fd %d from slave", __func__, i); for (j = 0; j < i; j++) close(new_fd[j]); free(chost); /* prepare reply */ buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "did not receive file descriptors"); return -1; } } debug3("%s: got fds stdin %d, stdout %d", __func__, new_fd[0], new_fd[1]); /* XXX support multiple child sessions in future */ if (c->have_remote_id) { debug2("%s: session already open", __func__); /* prepare reply */ buffer_put_int(r, MUX_S_FAILURE); buffer_put_int(r, rid); buffer_put_cstring(r, "Multiple sessions not supported"); cleanup: close(new_fd[0]); close(new_fd[1]); free(chost); return 0; } if (options.control_master == SSHCTL_MASTER_ASK || options.control_master == SSHCTL_MASTER_AUTO_ASK) { if (!ask_permission("Allow forward to %s:%u? ", chost, cport)) { debug2("%s: stdio fwd refused by user", __func__); /* prepare reply */ buffer_put_int(r, MUX_S_PERMISSION_DENIED); buffer_put_int(r, rid); buffer_put_cstring(r, "Permission denied"); goto cleanup; } } /* enable nonblocking unless tty */ if (!isatty(new_fd[0])) set_nonblock(new_fd[0]); if (!isatty(new_fd[1])) set_nonblock(new_fd[1]); nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]); nc->ctl_chan = c->self; /* link session -> control channel */ c->remote_id = nc->self; /* link control -> session channel */ c->have_remote_id = 1; debug2("%s: channel_new: %d linked to control channel %d", __func__, nc->self, nc->ctl_chan); channel_register_cleanup(ssh, nc->self, mux_master_session_cleanup_cb, 1); cctx = xcalloc(1, sizeof(*cctx)); cctx->rid = rid; channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx); c->mux_pause = 1; /* stop handling messages until open_confirm done */ /* reply is deferred, sent by mux_session_confirm */ return 0; } /* Callback on open confirmation in mux master for a mux stdio fwd session. */ static void mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg) { struct mux_stdio_confirm_ctx *cctx = arg; Channel *c, *cc; Buffer reply; if (cctx == NULL) fatal("%s: cctx == NULL", __func__); if ((c = channel_by_id(ssh, id)) == NULL) fatal("%s: no channel for id %d", __func__, id); if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) fatal("%s: channel %d lacks control channel %d", __func__, id, c->ctl_chan); if (!success) { debug3("%s: sending failure reply", __func__); /* prepare reply */ buffer_init(&reply); buffer_put_int(&reply, MUX_S_FAILURE); buffer_put_int(&reply, cctx->rid); buffer_put_cstring(&reply, "Session open refused by peer"); goto done; } debug3("%s: sending success reply", __func__); /* prepare reply */ buffer_init(&reply); buffer_put_int(&reply, MUX_S_SESSION_OPENED); buffer_put_int(&reply, cctx->rid); buffer_put_int(&reply, c->self); done: /* Send reply */ buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply)); buffer_free(&reply); if (cc->mux_pause <= 0) fatal("%s: mux_pause %d", __func__, cc->mux_pause); cc->mux_pause = 0; /* start processing messages again */ c->open_confirm_ctx = NULL; free(cctx); } static int process_mux_stop_listening(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { debug("%s: channel %d: stop listening", __func__, c->self); if (options.control_master == SSHCTL_MASTER_ASK || options.control_master == SSHCTL_MASTER_AUTO_ASK) { if (!ask_permission("Disable further multiplexing on shared " "connection to %s? ", host)) { debug2("%s: stop listen refused by user", __func__); buffer_put_int(r, MUX_S_PERMISSION_DENIED); buffer_put_int(r, rid); buffer_put_cstring(r, "Permission denied"); return 0; } } if (mux_listener_channel != NULL) { channel_free(ssh, mux_listener_channel); client_stop_mux(); free(options.control_path); options.control_path = NULL; mux_listener_channel = NULL; muxserver_sock = -1; } /* prepare reply */ buffer_put_int(r, MUX_S_OK); buffer_put_int(r, rid); return 0; } static int process_mux_proxy(struct ssh *ssh, u_int rid, Channel *c, Buffer *m, Buffer *r) { debug("%s: channel %d: proxy request", __func__, c->self); c->mux_rcb = channel_proxy_downstream; buffer_put_int(r, MUX_S_PROXY); buffer_put_int(r, rid); return 0; } /* Channel callbacks fired on read/write from mux slave fd */ static int mux_master_read_cb(struct ssh *ssh, Channel *c) { struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx; Buffer in, out; const u_char *ptr; u_int type, rid, have, i; int ret = -1; /* Setup ctx and */ if (c->mux_ctx == NULL) { state = xcalloc(1, sizeof(*state)); c->mux_ctx = state; channel_register_cleanup(ssh, c->self, mux_master_control_cleanup_cb, 0); /* Send hello */ buffer_init(&out); buffer_put_int(&out, MUX_MSG_HELLO); buffer_put_int(&out, SSHMUX_VER); /* no extensions */ buffer_put_string(c->output, buffer_ptr(&out), buffer_len(&out)); buffer_free(&out); debug3("%s: channel %d: hello sent", __func__, c->self); return 0; } buffer_init(&in); buffer_init(&out); /* Channel code ensures that we receive whole packets */ if ((ptr = buffer_get_string_ptr_ret(c->input, &have)) == NULL) { malf: error("%s: malformed message", __func__); goto out; } buffer_append(&in, ptr, have); if (buffer_get_int_ret(&type, &in) != 0) goto malf; debug3("%s: channel %d packet type 0x%08x len %u", __func__, c->self, type, buffer_len(&in)); if (type == MUX_MSG_HELLO) rid = 0; else { if (!state->hello_rcvd) { error("%s: expected MUX_MSG_HELLO(0x%08x), " "received 0x%08x", __func__, MUX_MSG_HELLO, type); goto out; } if (buffer_get_int_ret(&rid, &in) != 0) goto malf; } for (i = 0; mux_master_handlers[i].handler != NULL; i++) { if (type == mux_master_handlers[i].type) { ret = mux_master_handlers[i].handler(ssh, rid, c, &in, &out); break; } } if (mux_master_handlers[i].handler == NULL) { error("%s: unsupported mux message 0x%08x", __func__, type); buffer_put_int(&out, MUX_S_FAILURE); buffer_put_int(&out, rid); buffer_put_cstring(&out, "unsupported request"); ret = 0; } /* Enqueue reply packet */ if (buffer_len(&out) != 0) { buffer_put_string(c->output, buffer_ptr(&out), buffer_len(&out)); } out: buffer_free(&in); buffer_free(&out); return ret; } void mux_exit_message(struct ssh *ssh, Channel *c, int exitval) { Buffer m; Channel *mux_chan; debug3("%s: channel %d: exit message, exitval %d", __func__, c->self, exitval); if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) fatal("%s: channel %d missing mux channel %d", __func__, c->self, c->ctl_chan); /* Append exit message packet to control socket output queue */ buffer_init(&m); buffer_put_int(&m, MUX_S_EXIT_MESSAGE); buffer_put_int(&m, c->self); buffer_put_int(&m, exitval); buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m)); buffer_free(&m); } void mux_tty_alloc_failed(struct ssh *ssh, Channel *c) { Buffer m; Channel *mux_chan; debug3("%s: channel %d: TTY alloc failed", __func__, c->self); if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL) fatal("%s: channel %d missing mux channel %d", __func__, c->self, c->ctl_chan); /* Append exit message packet to control socket output queue */ buffer_init(&m); buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL); buffer_put_int(&m, c->self); buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m)); buffer_free(&m); } /* Prepare a mux master to listen on a Unix domain socket. */ void muxserver_listen(struct ssh *ssh) { mode_t old_umask; char *orig_control_path = options.control_path; char rbuf[16+1]; u_int i, r; int oerrno; if (options.control_path == NULL || options.control_master == SSHCTL_MASTER_NO) return; debug("setting up multiplex master socket"); /* * Use a temporary path before listen so we can pseudo-atomically * establish the listening socket in its final location to avoid * other processes racing in between bind() and listen() and hitting * an unready socket. */ for (i = 0; i < sizeof(rbuf) - 1; i++) { r = arc4random_uniform(26+26+10); rbuf[i] = (r < 26) ? 'a' + r : (r < 26*2) ? 'A' + r - 26 : '0' + r - 26 - 26; } rbuf[sizeof(rbuf) - 1] = '\0'; options.control_path = NULL; xasprintf(&options.control_path, "%s.%s", orig_control_path, rbuf); debug3("%s: temporary control path %s", __func__, options.control_path); old_umask = umask(0177); muxserver_sock = unix_listener(options.control_path, 64, 0); oerrno = errno; umask(old_umask); if (muxserver_sock < 0) { if (oerrno == EINVAL || oerrno == EADDRINUSE) { error("ControlSocket %s already exists, " "disabling multiplexing", options.control_path); disable_mux_master: if (muxserver_sock != -1) { close(muxserver_sock); muxserver_sock = -1; } free(orig_control_path); free(options.control_path); options.control_path = NULL; options.control_master = SSHCTL_MASTER_NO; return; } else { /* unix_listener() logs the error */ cleanup_exit(255); } } /* Now atomically "move" the mux socket into position */ if (link(options.control_path, orig_control_path) != 0) { if (errno != EEXIST) { fatal("%s: link mux listener %s => %s: %s", __func__, options.control_path, orig_control_path, strerror(errno)); } error("ControlSocket %s already exists, disabling multiplexing", orig_control_path); unlink(options.control_path); goto disable_mux_master; } unlink(options.control_path); free(options.control_path); options.control_path = orig_control_path; set_nonblock(muxserver_sock); mux_listener_channel = channel_new(ssh, "mux listener", SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, options.control_path, 1); mux_listener_channel->mux_rcb = mux_master_read_cb; debug3("%s: mux listener channel %d fd %d", __func__, mux_listener_channel->self, mux_listener_channel->sock); } /* Callback on open confirmation in mux master for a mux client session. */ static void mux_session_confirm(struct ssh *ssh, int id, int success, void *arg) { struct mux_session_confirm_ctx *cctx = arg; const char *display; Channel *c, *cc; int i; Buffer reply; if (cctx == NULL) fatal("%s: cctx == NULL", __func__); if ((c = channel_by_id(ssh, id)) == NULL) fatal("%s: no channel for id %d", __func__, id); if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL) fatal("%s: channel %d lacks control channel %d", __func__, id, c->ctl_chan); if (!success) { debug3("%s: sending failure reply", __func__); /* prepare reply */ buffer_init(&reply); buffer_put_int(&reply, MUX_S_FAILURE); buffer_put_int(&reply, cctx->rid); buffer_put_cstring(&reply, "Session open refused by peer"); goto done; } display = getenv("DISPLAY"); if (cctx->want_x_fwd && options.forward_x11 && display != NULL) { char *proto, *data; /* Get reasonable local authentication information. */ if (client_x11_get_proto(ssh, display, options.xauth_location, options.forward_x11_trusted, options.forward_x11_timeout, &proto, &data) == 0) { /* Request forwarding with authentication spoofing. */ debug("Requesting X11 forwarding with authentication " "spoofing."); x11_request_forwarding_with_spoofing(ssh, id, display, proto, data, 1); /* XXX exit_on_forward_failure */ client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN); } } if (cctx->want_agent_fwd && options.forward_agent) { debug("Requesting authentication agent forwarding."); channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0); packet_send(); } client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys, cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env); debug3("%s: sending success reply", __func__); /* prepare reply */ buffer_init(&reply); buffer_put_int(&reply, MUX_S_SESSION_OPENED); buffer_put_int(&reply, cctx->rid); buffer_put_int(&reply, c->self); done: /* Send reply */ buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply)); buffer_free(&reply); if (cc->mux_pause <= 0) fatal("%s: mux_pause %d", __func__, cc->mux_pause); cc->mux_pause = 0; /* start processing messages again */ c->open_confirm_ctx = NULL; buffer_free(&cctx->cmd); free(cctx->term); if (cctx->env != NULL) { for (i = 0; cctx->env[i] != NULL; i++) free(cctx->env[i]); free(cctx->env); } free(cctx); } /* ** Multiplexing client support */ /* Exit signal handler */ static void control_client_sighandler(int signo) { muxclient_terminate = signo; } /* * Relay signal handler - used to pass some signals from mux client to * mux master. */ static void control_client_sigrelay(int signo) { int save_errno = errno; if (muxserver_pid > 1) kill(muxserver_pid, signo); errno = save_errno; } static int mux_client_read(int fd, Buffer *b, u_int need) { u_int have; ssize_t len; u_char *p; struct pollfd pfd; pfd.fd = fd; pfd.events = POLLIN; p = buffer_append_space(b, need); for (have = 0; have < need; ) { if (muxclient_terminate) { errno = EINTR; return -1; } len = read(fd, p + have, need - have); if (len < 0) { switch (errno) { #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) case EWOULDBLOCK: #endif case EAGAIN: (void)poll(&pfd, 1, -1); /* FALLTHROUGH */ case EINTR: continue; default: return -1; } } if (len == 0) { errno = EPIPE; return -1; } have += (u_int)len; } return 0; } static int mux_client_write_packet(int fd, Buffer *m) { Buffer queue; u_int have, need; int oerrno, len; u_char *ptr; struct pollfd pfd; pfd.fd = fd; pfd.events = POLLOUT; buffer_init(&queue); buffer_put_string(&queue, buffer_ptr(m), buffer_len(m)); need = buffer_len(&queue); ptr = buffer_ptr(&queue); for (have = 0; have < need; ) { if (muxclient_terminate) { buffer_free(&queue); errno = EINTR; return -1; } len = write(fd, ptr + have, need - have); if (len < 0) { switch (errno) { #if defined(EWOULDBLOCK) && (EWOULDBLOCK != EAGAIN) case EWOULDBLOCK: #endif case EAGAIN: (void)poll(&pfd, 1, -1); /* FALLTHROUGH */ case EINTR: continue; default: oerrno = errno; buffer_free(&queue); errno = oerrno; return -1; } } if (len == 0) { buffer_free(&queue); errno = EPIPE; return -1; } have += (u_int)len; } buffer_free(&queue); return 0; } static int mux_client_read_packet(int fd, Buffer *m) { Buffer queue; u_int need, have; const u_char *ptr; int oerrno; buffer_init(&queue); if (mux_client_read(fd, &queue, 4) != 0) { if ((oerrno = errno) == EPIPE) debug3("%s: read header failed: %s", __func__, strerror(errno)); buffer_free(&queue); errno = oerrno; return -1; } need = get_u32(buffer_ptr(&queue)); if (mux_client_read(fd, &queue, need) != 0) { oerrno = errno; debug3("%s: read body failed: %s", __func__, strerror(errno)); buffer_free(&queue); errno = oerrno; return -1; } ptr = buffer_get_string_ptr(&queue, &have); buffer_append(m, ptr, have); buffer_free(&queue); return 0; } static int mux_client_hello_exchange(int fd) { Buffer m; u_int type, ver; int ret = -1; buffer_init(&m); buffer_put_int(&m, MUX_MSG_HELLO); buffer_put_int(&m, SSHMUX_VER); /* no extensions */ if (mux_client_write_packet(fd, &m) != 0) { debug("%s: write packet: %s", __func__, strerror(errno)); goto out; } buffer_clear(&m); /* Read their HELLO */ if (mux_client_read_packet(fd, &m) != 0) { debug("%s: read packet failed", __func__); goto out; } type = buffer_get_int(&m); if (type != MUX_MSG_HELLO) { error("%s: expected HELLO (%u) received %u", __func__, MUX_MSG_HELLO, type); goto out; } ver = buffer_get_int(&m); if (ver != SSHMUX_VER) { error("Unsupported multiplexing protocol version %d " "(expected %d)", ver, SSHMUX_VER); goto out; } debug2("%s: master version %u", __func__, ver); /* No extensions are presently defined */ while (buffer_len(&m) > 0) { char *name = buffer_get_string(&m, NULL); char *value = buffer_get_string(&m, NULL); debug2("Unrecognised master extension \"%s\"", name); free(name); free(value); } /* success */ ret = 0; out: buffer_free(&m); return ret; } static u_int mux_client_request_alive(int fd) { Buffer m; char *e; u_int pid, type, rid; debug3("%s: entering", __func__); buffer_init(&m); buffer_put_int(&m, MUX_C_ALIVE_CHECK); buffer_put_int(&m, muxclient_request_id); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); /* Read their reply */ if (mux_client_read_packet(fd, &m) != 0) { buffer_free(&m); return 0; } type = buffer_get_int(&m); if (type != MUX_S_ALIVE) { e = buffer_get_string(&m, NULL); fatal("%s: master returned error: %s", __func__, e); } if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); pid = buffer_get_int(&m); buffer_free(&m); debug3("%s: done pid = %u", __func__, pid); muxclient_request_id++; return pid; } static void mux_client_request_terminate(int fd) { Buffer m; char *e; u_int type, rid; debug3("%s: entering", __func__); buffer_init(&m); buffer_put_int(&m, MUX_C_TERMINATE); buffer_put_int(&m, muxclient_request_id); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); /* Read their reply */ if (mux_client_read_packet(fd, &m) != 0) { /* Remote end exited already */ if (errno == EPIPE) { buffer_free(&m); return; } fatal("%s: read from master failed: %s", __func__, strerror(errno)); } type = buffer_get_int(&m); if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); switch (type) { case MUX_S_OK: break; case MUX_S_PERMISSION_DENIED: e = buffer_get_string(&m, NULL); fatal("Master refused termination request: %s", e); case MUX_S_FAILURE: e = buffer_get_string(&m, NULL); fatal("%s: termination request failed: %s", __func__, e); default: fatal("%s: unexpected response from master 0x%08x", __func__, type); } buffer_free(&m); muxclient_request_id++; } static int mux_client_forward(int fd, int cancel_flag, u_int ftype, struct Forward *fwd) { Buffer m; char *e, *fwd_desc; u_int type, rid; fwd_desc = format_forward(ftype, fwd); debug("Requesting %s %s", cancel_flag ? "cancellation of" : "forwarding of", fwd_desc); free(fwd_desc); buffer_init(&m); buffer_put_int(&m, cancel_flag ? MUX_C_CLOSE_FWD : MUX_C_OPEN_FWD); buffer_put_int(&m, muxclient_request_id); buffer_put_int(&m, ftype); if (fwd->listen_path != NULL) { buffer_put_cstring(&m, fwd->listen_path); } else { buffer_put_cstring(&m, fwd->listen_host == NULL ? "" : (*fwd->listen_host == '\0' ? "*" : fwd->listen_host)); } buffer_put_int(&m, fwd->listen_port); if (fwd->connect_path != NULL) { buffer_put_cstring(&m, fwd->connect_path); } else { buffer_put_cstring(&m, fwd->connect_host == NULL ? "" : fwd->connect_host); } buffer_put_int(&m, fwd->connect_port); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); /* Read their reply */ if (mux_client_read_packet(fd, &m) != 0) { buffer_free(&m); return -1; } type = buffer_get_int(&m); if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); switch (type) { case MUX_S_OK: break; case MUX_S_REMOTE_PORT: if (cancel_flag) fatal("%s: got MUX_S_REMOTE_PORT for cancel", __func__); fwd->allocated_port = buffer_get_int(&m); verbose("Allocated port %u for remote forward to %s:%d", fwd->allocated_port, fwd->connect_host ? fwd->connect_host : "", fwd->connect_port); if (muxclient_command == SSHMUX_COMMAND_FORWARD) fprintf(stdout, "%i\n", fwd->allocated_port); break; case MUX_S_PERMISSION_DENIED: e = buffer_get_string(&m, NULL); buffer_free(&m); error("Master refused forwarding request: %s", e); return -1; case MUX_S_FAILURE: e = buffer_get_string(&m, NULL); buffer_free(&m); error("%s: forwarding request failed: %s", __func__, e); return -1; default: fatal("%s: unexpected response from master 0x%08x", __func__, type); } buffer_free(&m); muxclient_request_id++; return 0; } static int mux_client_forwards(int fd, int cancel_flag) { int i, ret = 0; debug3("%s: %s forwardings: %d local, %d remote", __func__, cancel_flag ? "cancel" : "request", options.num_local_forwards, options.num_remote_forwards); /* XXX ExitOnForwardingFailure */ for (i = 0; i < options.num_local_forwards; i++) { if (mux_client_forward(fd, cancel_flag, options.local_forwards[i].connect_port == 0 ? MUX_FWD_DYNAMIC : MUX_FWD_LOCAL, options.local_forwards + i) != 0) ret = -1; } for (i = 0; i < options.num_remote_forwards; i++) { if (mux_client_forward(fd, cancel_flag, MUX_FWD_REMOTE, options.remote_forwards + i) != 0) ret = -1; } return ret; } static int mux_client_request_session(int fd) { Buffer m; char *e, *term; u_int i, rid, sid, esid, exitval, type, exitval_seen; extern char **environ; int devnull, rawmode; debug3("%s: entering", __func__); if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { error("%s: master alive request failed", __func__); return -1; } signal(SIGPIPE, SIG_IGN); if (stdin_null_flag) { if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) fatal("open(/dev/null): %s", strerror(errno)); if (dup2(devnull, STDIN_FILENO) == -1) fatal("dup2: %s", strerror(errno)); if (devnull > STDERR_FILENO) close(devnull); } term = getenv("TERM"); buffer_init(&m); buffer_put_int(&m, MUX_C_NEW_SESSION); buffer_put_int(&m, muxclient_request_id); buffer_put_cstring(&m, ""); /* reserved */ buffer_put_int(&m, tty_flag); buffer_put_int(&m, options.forward_x11); buffer_put_int(&m, options.forward_agent); buffer_put_int(&m, subsystem_flag); buffer_put_int(&m, options.escape_char == SSH_ESCAPECHAR_NONE ? 0xffffffff : (u_int)options.escape_char); buffer_put_cstring(&m, term == NULL ? "" : term); buffer_put_string(&m, buffer_ptr(&command), buffer_len(&command)); if (options.num_send_env > 0 && environ != NULL) { /* Pass environment */ for (i = 0; environ[i] != NULL; i++) { if (env_permitted(environ[i])) { buffer_put_cstring(&m, environ[i]); } } } if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); /* Send the stdio file descriptors */ if (mm_send_fd(fd, STDIN_FILENO) == -1 || mm_send_fd(fd, STDOUT_FILENO) == -1 || mm_send_fd(fd, STDERR_FILENO) == -1) fatal("%s: send fds failed", __func__); debug3("%s: session request sent", __func__); /* Read their reply */ buffer_clear(&m); if (mux_client_read_packet(fd, &m) != 0) { error("%s: read from master failed: %s", __func__, strerror(errno)); buffer_free(&m); return -1; } type = buffer_get_int(&m); if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); switch (type) { case MUX_S_SESSION_OPENED: sid = buffer_get_int(&m); debug("%s: master session id: %u", __func__, sid); break; case MUX_S_PERMISSION_DENIED: e = buffer_get_string(&m, NULL); buffer_free(&m); error("Master refused session request: %s", e); return -1; case MUX_S_FAILURE: e = buffer_get_string(&m, NULL); buffer_free(&m); error("%s: session request failed: %s", __func__, e); return -1; default: buffer_free(&m); error("%s: unexpected response from master 0x%08x", __func__, type); return -1; } muxclient_request_id++; if (pledge("stdio proc tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); platform_pledge_mux(); signal(SIGHUP, control_client_sighandler); signal(SIGINT, control_client_sighandler); signal(SIGTERM, control_client_sighandler); signal(SIGWINCH, control_client_sigrelay); rawmode = tty_flag; if (tty_flag) enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); /* * Stick around until the controlee closes the client_fd. * Before it does, it is expected to write an exit message. * This process must read the value and wait for the closure of * the client_fd; if this one closes early, the multiplex master will * terminate early too (possibly losing data). */ for (exitval = 255, exitval_seen = 0;;) { buffer_clear(&m); if (mux_client_read_packet(fd, &m) != 0) break; type = buffer_get_int(&m); switch (type) { case MUX_S_TTY_ALLOC_FAIL: if ((esid = buffer_get_int(&m)) != sid) fatal("%s: tty alloc fail on unknown session: " "my id %u theirs %u", __func__, sid, esid); leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); rawmode = 0; continue; case MUX_S_EXIT_MESSAGE: if ((esid = buffer_get_int(&m)) != sid) fatal("%s: exit on unknown session: " "my id %u theirs %u", __func__, sid, esid); if (exitval_seen) fatal("%s: exitval sent twice", __func__); exitval = buffer_get_int(&m); exitval_seen = 1; continue; default: e = buffer_get_string(&m, NULL); fatal("%s: master returned error: %s", __func__, e); } } close(fd); if (rawmode) leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); if (muxclient_terminate) { debug2("Exiting on signal: %s", strsignal(muxclient_terminate)); exitval = 255; } else if (!exitval_seen) { debug2("Control master terminated unexpectedly"); exitval = 255; } else debug2("Received exit status from master %d", exitval); if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET) fprintf(stderr, "Shared connection to %s closed.\r\n", host); exit(exitval); } static int mux_client_proxy(int fd) { Buffer m; char *e; u_int type, rid; buffer_init(&m); buffer_put_int(&m, MUX_C_PROXY); buffer_put_int(&m, muxclient_request_id); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); /* Read their reply */ if (mux_client_read_packet(fd, &m) != 0) { buffer_free(&m); return 0; } type = buffer_get_int(&m); if (type != MUX_S_PROXY) { e = buffer_get_string(&m, NULL); fatal("%s: master returned error: %s", __func__, e); } if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); buffer_free(&m); debug3("%s: done", __func__); muxclient_request_id++; return 0; } static int mux_client_request_stdio_fwd(int fd) { Buffer m; char *e; u_int type, rid, sid; int devnull; debug3("%s: entering", __func__); if ((muxserver_pid = mux_client_request_alive(fd)) == 0) { error("%s: master alive request failed", __func__); return -1; } signal(SIGPIPE, SIG_IGN); if (stdin_null_flag) { if ((devnull = open(_PATH_DEVNULL, O_RDONLY)) == -1) fatal("open(/dev/null): %s", strerror(errno)); if (dup2(devnull, STDIN_FILENO) == -1) fatal("dup2: %s", strerror(errno)); if (devnull > STDERR_FILENO) close(devnull); } buffer_init(&m); buffer_put_int(&m, MUX_C_NEW_STDIO_FWD); buffer_put_int(&m, muxclient_request_id); buffer_put_cstring(&m, ""); /* reserved */ buffer_put_cstring(&m, options.stdio_forward_host); buffer_put_int(&m, options.stdio_forward_port); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); /* Send the stdio file descriptors */ if (mm_send_fd(fd, STDIN_FILENO) == -1 || mm_send_fd(fd, STDOUT_FILENO) == -1) fatal("%s: send fds failed", __func__); if (pledge("stdio proc tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); platform_pledge_mux(); debug3("%s: stdio forward request sent", __func__); /* Read their reply */ buffer_clear(&m); if (mux_client_read_packet(fd, &m) != 0) { error("%s: read from master failed: %s", __func__, strerror(errno)); buffer_free(&m); return -1; } type = buffer_get_int(&m); if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); switch (type) { case MUX_S_SESSION_OPENED: sid = buffer_get_int(&m); debug("%s: master session id: %u", __func__, sid); break; case MUX_S_PERMISSION_DENIED: e = buffer_get_string(&m, NULL); buffer_free(&m); fatal("Master refused stdio forwarding request: %s", e); case MUX_S_FAILURE: e = buffer_get_string(&m, NULL); buffer_free(&m); fatal("Stdio forwarding request failed: %s", e); default: buffer_free(&m); error("%s: unexpected response from master 0x%08x", __func__, type); return -1; } muxclient_request_id++; signal(SIGHUP, control_client_sighandler); signal(SIGINT, control_client_sighandler); signal(SIGTERM, control_client_sighandler); signal(SIGWINCH, control_client_sigrelay); /* * Stick around until the controlee closes the client_fd. */ buffer_clear(&m); if (mux_client_read_packet(fd, &m) != 0) { if (errno == EPIPE || (errno == EINTR && muxclient_terminate != 0)) return 0; fatal("%s: mux_client_read_packet: %s", __func__, strerror(errno)); } fatal("%s: master returned unexpected message %u", __func__, type); } static void mux_client_request_stop_listening(int fd) { Buffer m; char *e; u_int type, rid; debug3("%s: entering", __func__); buffer_init(&m); buffer_put_int(&m, MUX_C_STOP_LISTENING); buffer_put_int(&m, muxclient_request_id); if (mux_client_write_packet(fd, &m) != 0) fatal("%s: write packet: %s", __func__, strerror(errno)); buffer_clear(&m); /* Read their reply */ if (mux_client_read_packet(fd, &m) != 0) fatal("%s: read from master failed: %s", __func__, strerror(errno)); type = buffer_get_int(&m); if ((rid = buffer_get_int(&m)) != muxclient_request_id) fatal("%s: out of sequence reply: my id %u theirs %u", __func__, muxclient_request_id, rid); switch (type) { case MUX_S_OK: break; case MUX_S_PERMISSION_DENIED: e = buffer_get_string(&m, NULL); fatal("Master refused stop listening request: %s", e); case MUX_S_FAILURE: e = buffer_get_string(&m, NULL); fatal("%s: stop listening request failed: %s", __func__, e); default: fatal("%s: unexpected response from master 0x%08x", __func__, type); } buffer_free(&m); muxclient_request_id++; } /* Multiplex client main loop. */ int muxclient(const char *path) { struct sockaddr_un addr; int sock; u_int pid; if (muxclient_command == 0) { if (options.stdio_forward_host != NULL) muxclient_command = SSHMUX_COMMAND_STDIO_FWD; else muxclient_command = SSHMUX_COMMAND_OPEN; } switch (options.control_master) { case SSHCTL_MASTER_AUTO: case SSHCTL_MASTER_AUTO_ASK: debug("auto-mux: Trying existing master"); /* FALLTHROUGH */ case SSHCTL_MASTER_NO: break; default: return -1; } memset(&addr, '\0', sizeof(addr)); addr.sun_family = AF_UNIX; if (strlcpy(addr.sun_path, path, sizeof(addr.sun_path)) >= sizeof(addr.sun_path)) fatal("ControlPath too long ('%s' >= %u bytes)", path, (unsigned int)sizeof(addr.sun_path)); if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) fatal("%s socket(): %s", __func__, strerror(errno)); if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == -1) { switch (muxclient_command) { case SSHMUX_COMMAND_OPEN: case SSHMUX_COMMAND_STDIO_FWD: break; default: fatal("Control socket connect(%.100s): %s", path, strerror(errno)); } if (errno == ECONNREFUSED && options.control_master != SSHCTL_MASTER_NO) { debug("Stale control socket %.100s, unlinking", path); unlink(path); } else if (errno == ENOENT) { debug("Control socket \"%.100s\" does not exist", path); } else { error("Control socket connect(%.100s): %s", path, strerror(errno)); } close(sock); return -1; } set_nonblock(sock); if (mux_client_hello_exchange(sock) != 0) { error("%s: master hello exchange failed", __func__); close(sock); return -1; } switch (muxclient_command) { case SSHMUX_COMMAND_ALIVE_CHECK: if ((pid = mux_client_request_alive(sock)) == 0) fatal("%s: master alive check failed", __func__); fprintf(stderr, "Master running (pid=%u)\r\n", pid); exit(0); case SSHMUX_COMMAND_TERMINATE: mux_client_request_terminate(sock); if (options.log_level != SYSLOG_LEVEL_QUIET) fprintf(stderr, "Exit request sent.\r\n"); exit(0); case SSHMUX_COMMAND_FORWARD: if (mux_client_forwards(sock, 0) != 0) fatal("%s: master forward request failed", __func__); exit(0); case SSHMUX_COMMAND_OPEN: if (mux_client_forwards(sock, 0) != 0) { error("%s: master forward request failed", __func__); return -1; } mux_client_request_session(sock); return -1; case SSHMUX_COMMAND_STDIO_FWD: mux_client_request_stdio_fwd(sock); exit(0); case SSHMUX_COMMAND_STOP: mux_client_request_stop_listening(sock); if (options.log_level != SYSLOG_LEVEL_QUIET) fprintf(stderr, "Stop listening request sent.\r\n"); exit(0); case SSHMUX_COMMAND_CANCEL_FWD: if (mux_client_forwards(sock, 1) != 0) error("%s: master cancel forward request failed", __func__); exit(0); case SSHMUX_COMMAND_PROXY: mux_client_proxy(sock); return (sock); default: fatal("unrecognised muxclient_command %d", muxclient_command); } }