/* $OpenBSD: serverloop.c,v 1.223 2020/07/03 06:29:57 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * Server main loop for handling the interactive session. * * 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 by Markus Friedl. * Copyright (c) 2000, 2001 Markus Friedl. 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 "xmalloc.h" #include "packet.h" #include "sshbuf.h" #include "log.h" #include "misc.h" #include "servconf.h" #include "canohost.h" #include "sshpty.h" #include "channels.h" #include "compat.h" #include "ssh2.h" #include "sshkey.h" #include "cipher.h" #include "kex.h" #include "hostfile.h" #include "auth.h" #include "session.h" #include "dispatch.h" #include "auth-options.h" #include "serverloop.h" #include "ssherr.h" extern ServerOptions options; /* XXX */ extern Authctxt *the_authctxt; extern struct sshauthopt *auth_opts; extern int use_privsep; static int no_more_sessions = 0; /* Disallow further sessions. */ /* * This SIGCHLD kludge is used to detect when the child exits. The server * will exit after that, as soon as forwarded connections have terminated. */ static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ /* Cleanup on signals (!use_privsep case only) */ static volatile sig_atomic_t received_sigterm = 0; /* prototypes */ static void server_init_dispatch(struct ssh *); /* requested tunnel forwarding interface(s), shared with session.c */ char *tun_fwd_ifnames = NULL; /* returns 1 if bind to specified port by specified user is permitted */ static int bind_permitted(int port, uid_t uid) { if (use_privsep) return 1; /* allow system to decide */ if (port < IPPORT_RESERVED && uid != 0) return 0; return 1; } /* * we write to this pipe if a SIGCHLD is caught in order to avoid * the race between select() and child_terminated */ static int notify_pipe[2]; static void notify_setup(void) { if (pipe(notify_pipe) == -1) { error("pipe(notify_pipe) failed %s", strerror(errno)); } else if ((fcntl(notify_pipe[0], F_SETFD, FD_CLOEXEC) == -1) || (fcntl(notify_pipe[1], F_SETFD, FD_CLOEXEC) == -1)) { error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); close(notify_pipe[0]); close(notify_pipe[1]); } else { set_nonblock(notify_pipe[0]); set_nonblock(notify_pipe[1]); return; } notify_pipe[0] = -1; /* read end */ notify_pipe[1] = -1; /* write end */ } static void notify_parent(void) { if (notify_pipe[1] != -1) (void)write(notify_pipe[1], "", 1); } static void notify_prepare(fd_set *readset) { if (notify_pipe[0] != -1) FD_SET(notify_pipe[0], readset); } static void notify_done(fd_set *readset) { char c; if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) while (read(notify_pipe[0], &c, 1) != -1) debug2("%s: reading", __func__); } /*ARGSUSED*/ static void sigchld_handler(int sig) { int save_errno = errno; child_terminated = 1; notify_parent(); errno = save_errno; } /*ARGSUSED*/ static void sigterm_handler(int sig) { received_sigterm = sig; } static void client_alive_check(struct ssh *ssh) { char remote_id[512]; int r, channel_id; /* timeout, check to see how many we have had */ if (options.client_alive_count_max > 0 && ssh_packet_inc_alive_timeouts(ssh) > options.client_alive_count_max) { sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id)); logit("Timeout, client not responding from %s", remote_id); cleanup_exit(255); } /* * send a bogus global/channel request with "wantreply", * we should get back a failure */ if ((channel_id = channel_find_open(ssh)) == -1) { if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || (r = sshpkt_put_cstring(ssh, "keepalive@openssh.com")) != 0 || (r = sshpkt_put_u8(ssh, 1)) != 0) /* boolean: want reply */ fatal("%s: %s", __func__, ssh_err(r)); } else { channel_request_start(ssh, channel_id, "keepalive@openssh.com", 1); } if ((r = sshpkt_send(ssh)) != 0) fatal("%s: %s", __func__, ssh_err(r)); } /* * Sleep in select() until we can do something. This will initialize the * select masks. Upon return, the masks will indicate which descriptors * have data or can accept data. Optionally, a maximum time can be specified * for the duration of the wait (0 = infinite). */ static void wait_until_can_do_something(struct ssh *ssh, int connection_in, int connection_out, fd_set **readsetp, fd_set **writesetp, int *maxfdp, u_int *nallocp, u_int64_t max_time_ms) { struct timeval tv, *tvp; int ret; time_t minwait_secs = 0; int client_alive_scheduled = 0; /* time we last heard from the client OR sent a keepalive */ static time_t last_client_time; /* Allocate and update select() masks for channel descriptors. */ channel_prepare_select(ssh, readsetp, writesetp, maxfdp, nallocp, &minwait_secs); /* XXX need proper deadline system for rekey/client alive */ if (minwait_secs != 0) max_time_ms = MINIMUM(max_time_ms, (u_int)minwait_secs * 1000); /* * if using client_alive, set the max timeout accordingly, * and indicate that this particular timeout was for client * alive by setting the client_alive_scheduled flag. * * this could be randomized somewhat to make traffic * analysis more difficult, but we're not doing it yet. */ if (options.client_alive_interval) { uint64_t keepalive_ms = (uint64_t)options.client_alive_interval * 1000; if (max_time_ms == 0 || max_time_ms > keepalive_ms) { max_time_ms = keepalive_ms; client_alive_scheduled = 1; } if (last_client_time == 0) last_client_time = monotime(); } #if 0 /* wrong: bad condition XXX */ if (channel_not_very_much_buffered_data()) #endif FD_SET(connection_in, *readsetp); notify_prepare(*readsetp); /* * If we have buffered packet data going to the client, mark that * descriptor. */ if (ssh_packet_have_data_to_write(ssh)) FD_SET(connection_out, *writesetp); /* * If child has terminated and there is enough buffer space to read * from it, then read as much as is available and exit. */ if (child_terminated && ssh_packet_not_very_much_data_to_write(ssh)) if (max_time_ms == 0 || client_alive_scheduled) max_time_ms = 100; if (max_time_ms == 0) tvp = NULL; else { tv.tv_sec = max_time_ms / 1000; tv.tv_usec = 1000 * (max_time_ms % 1000); tvp = &tv; } /* Wait for something to happen, or the timeout to expire. */ ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); if (ret == -1) { memset(*readsetp, 0, *nallocp); memset(*writesetp, 0, *nallocp); if (errno != EINTR) error("select: %.100s", strerror(errno)); } else if (client_alive_scheduled) { time_t now = monotime(); /* * If the select timed out, or returned for some other reason * but we haven't heard from the client in time, send keepalive. */ if (ret == 0 || (last_client_time != 0 && last_client_time + options.client_alive_interval <= now)) { client_alive_check(ssh); last_client_time = now; } else if (FD_ISSET(connection_in, *readsetp)) { last_client_time = now; } } notify_done(*readsetp); } /* * Processes input from the client and the program. Input data is stored * in buffers and processed later. */ static int process_input(struct ssh *ssh, fd_set *readset, int connection_in) { int r, len; char buf[16384]; /* Read and buffer any input data from the client. */ if (FD_ISSET(connection_in, readset)) { len = read(connection_in, buf, sizeof(buf)); if (len == 0) { verbose("Connection closed by %.100s port %d", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); return -1; } else if (len == -1) { if (errno != EINTR && errno != EAGAIN) { verbose("Read error from remote host " "%.100s port %d: %.100s", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), strerror(errno)); cleanup_exit(255); } } else { /* Buffer any received data. */ if ((r = ssh_packet_process_incoming(ssh, buf, len)) != 0) fatal("%s: ssh_packet_process_incoming: %s", __func__, ssh_err(r)); } } return 0; } /* * Sends data from internal buffers to client program stdin. */ static void process_output(struct ssh *ssh, fd_set *writeset, int connection_out) { int r; /* Send any buffered packet data to the client. */ if (FD_ISSET(connection_out, writeset)) { if ((r = ssh_packet_write_poll(ssh)) != 0) { sshpkt_fatal(ssh, r, "%s: ssh_packet_write_poll", __func__); } } } static void process_buffered_input_packets(struct ssh *ssh) { ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL); } static void collect_children(struct ssh *ssh) { pid_t pid; sigset_t oset, nset; int status; /* block SIGCHLD while we check for dead children */ sigemptyset(&nset); sigaddset(&nset, SIGCHLD); sigprocmask(SIG_BLOCK, &nset, &oset); if (child_terminated) { debug("Received SIGCHLD."); while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || (pid == -1 && errno == EINTR)) if (pid > 0) session_close_by_pid(ssh, pid, status); child_terminated = 0; } sigprocmask(SIG_SETMASK, &oset, NULL); } void server_loop2(struct ssh *ssh, Authctxt *authctxt) { fd_set *readset = NULL, *writeset = NULL; int max_fd; u_int nalloc = 0, connection_in, connection_out; u_int64_t rekey_timeout_ms = 0; debug("Entering interactive session for SSH2."); ssh_signal(SIGCHLD, sigchld_handler); child_terminated = 0; connection_in = ssh_packet_get_connection_in(ssh); connection_out = ssh_packet_get_connection_out(ssh); if (!use_privsep) { ssh_signal(SIGTERM, sigterm_handler); ssh_signal(SIGINT, sigterm_handler); ssh_signal(SIGQUIT, sigterm_handler); } notify_setup(); max_fd = MAXIMUM(connection_in, connection_out); max_fd = MAXIMUM(max_fd, notify_pipe[0]); server_init_dispatch(ssh); for (;;) { process_buffered_input_packets(ssh); if (!ssh_packet_is_rekeying(ssh) && ssh_packet_not_very_much_data_to_write(ssh)) channel_output_poll(ssh); if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) { rekey_timeout_ms = ssh_packet_get_rekey_timeout(ssh) * 1000; } else { rekey_timeout_ms = 0; } wait_until_can_do_something(ssh, connection_in, connection_out, &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms); if (received_sigterm) { logit("Exiting on signal %d", (int)received_sigterm); /* Clean up sessions, utmp, etc. */ cleanup_exit(255); } collect_children(ssh); if (!ssh_packet_is_rekeying(ssh)) channel_after_select(ssh, readset, writeset); if (process_input(ssh, readset, connection_in) < 0) break; process_output(ssh, writeset, connection_out); } collect_children(ssh); free(readset); free(writeset); /* free all channels, no more reads and writes */ channel_free_all(ssh); /* free remaining sessions, e.g. remove wtmp entries */ session_destroy_all(ssh, NULL); } static int server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh) { debug("Got %d/%u for keepalive", type, seq); /* * reset timeout, since we got a sane answer from the client. * even if this was generated by something other than * the bogus CHANNEL_REQUEST we send for keepalives. */ ssh_packet_set_alive_timeouts(ssh, 0); return 0; } static Channel * server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) { Channel *c = NULL; char *target = NULL, *originator = NULL; u_int target_port = 0, originator_port = 0; int r; if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &target_port)) != 0 || (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || (r = sshpkt_get_end(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); if (target_port > 0xFFFF) { error("%s: invalid target port", __func__); *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; goto out; } if (originator_port > 0xFFFF) { error("%s: invalid originator port", __func__); *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; goto out; } debug("%s: originator %s port %u, target %s port %u", __func__, originator, originator_port, target, target_port); /* XXX fine grained permissions */ if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && auth_opts->permit_port_forwarding_flag && !options.disable_forwarding) { c = channel_connect_to_port(ssh, target, target_port, "direct-tcpip", "direct-tcpip", reason, errmsg); } else { logit("refused local port forward: " "originator %s port %d, target %s port %d", originator, originator_port, target, target_port); if (reason != NULL) *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED; } out: free(originator); free(target); return c; } static Channel * server_request_direct_streamlocal(struct ssh *ssh) { Channel *c = NULL; char *target = NULL, *originator = NULL; u_int originator_port = 0; struct passwd *pw = the_authctxt->pw; int r; if (pw == NULL || !the_authctxt->valid) fatal("%s: no/invalid user", __func__); if ((r = sshpkt_get_cstring(ssh, &target, NULL)) != 0 || (r = sshpkt_get_cstring(ssh, &originator, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &originator_port)) != 0 || (r = sshpkt_get_end(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); if (originator_port > 0xFFFF) { error("%s: invalid originator port", __func__); goto out; } debug("%s: originator %s port %d, target %s", __func__, originator, originator_port, target); /* XXX fine grained permissions */ if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && auth_opts->permit_port_forwarding_flag && !options.disable_forwarding && (pw->pw_uid == 0 || use_privsep)) { c = channel_connect_to_path(ssh, target, "direct-streamlocal@openssh.com", "direct-streamlocal"); } else { logit("refused streamlocal port forward: " "originator %s port %d, target %s", originator, originator_port, target); } out: free(originator); free(target); return c; } static Channel * server_request_tun(struct ssh *ssh) { Channel *c = NULL; u_int mode, tun; int r, sock; char *tmp, *ifname = NULL; if ((r = sshpkt_get_u32(ssh, &mode)) != 0) sshpkt_fatal(ssh, r, "%s: parse mode", __func__); switch (mode) { case SSH_TUNMODE_POINTOPOINT: case SSH_TUNMODE_ETHERNET: break; default: ssh_packet_send_debug(ssh, "Unsupported tunnel device mode."); return NULL; } if ((options.permit_tun & mode) == 0) { ssh_packet_send_debug(ssh, "Server has rejected tunnel device " "forwarding"); return NULL; } if ((r = sshpkt_get_u32(ssh, &tun)) != 0) sshpkt_fatal(ssh, r, "%s: parse device", __func__); if (tun > INT_MAX) { debug("%s: invalid tun", __func__); goto done; } if (auth_opts->force_tun_device != -1) { if (tun != SSH_TUNID_ANY && auth_opts->force_tun_device != (int)tun) goto done; tun = auth_opts->force_tun_device; } sock = tun_open(tun, mode, &ifname); if (sock < 0) goto done; debug("Tunnel forwarding using interface %s", ifname); c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); c->datagram = 1; /* * Update the list of names exposed to the session * XXX remove these if the tunnels are closed (won't matter * much if they are already in the environment though) */ tmp = tun_fwd_ifnames; xasprintf(&tun_fwd_ifnames, "%s%s%s", tun_fwd_ifnames == NULL ? "" : tun_fwd_ifnames, tun_fwd_ifnames == NULL ? "" : ",", ifname); free(tmp); free(ifname); done: if (c == NULL) ssh_packet_send_debug(ssh, "Failed to open the tunnel device."); return c; } static Channel * server_request_session(struct ssh *ssh) { Channel *c; int r; debug("input_session_request"); if ((r = sshpkt_get_end(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); if (no_more_sessions) { ssh_packet_disconnect(ssh, "Possible attack: attempt to open a " "session after additional sessions disabled"); } /* * A server session has no fd to read or write until a * CHANNEL_REQUEST for a shell is made, so we set the type to * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all * CHANNEL_REQUEST messages is registered. */ c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL, -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 0, "server-session", 1); if (session_open(the_authctxt, c->self) != 1) { debug("session open failed, free channel %d", c->self); channel_free(ssh, c); return NULL; } channel_register_cleanup(ssh, c->self, session_close_by_channel, 0); return c; } static int server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) { Channel *c = NULL; char *ctype = NULL; const char *errmsg = NULL; int r, reason = SSH2_OPEN_CONNECT_FAILED; u_int rchan = 0, rmaxpack = 0, rwindow = 0; if ((r = sshpkt_get_cstring(ssh, &ctype, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &rchan)) != 0 || (r = sshpkt_get_u32(ssh, &rwindow)) != 0 || (r = sshpkt_get_u32(ssh, &rmaxpack)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); debug("%s: ctype %s rchan %u win %u max %u", __func__, ctype, rchan, rwindow, rmaxpack); if (strcmp(ctype, "session") == 0) { c = server_request_session(ssh); } else if (strcmp(ctype, "direct-tcpip") == 0) { c = server_request_direct_tcpip(ssh, &reason, &errmsg); } else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) { c = server_request_direct_streamlocal(ssh); } else if (strcmp(ctype, "tun@openssh.com") == 0) { c = server_request_tun(ssh); } if (c != NULL) { debug("%s: confirm %s", __func__, ctype); c->remote_id = rchan; c->have_remote_id = 1; c->remote_window = rwindow; c->remote_maxpacket = rmaxpack; if (c->type != SSH_CHANNEL_CONNECTING) { 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) { sshpkt_fatal(ssh, r, "%s: send open confirm", __func__); } } } else { debug("%s: failure %s", __func__, ctype); if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 || (r = sshpkt_put_u32(ssh, rchan)) != 0 || (r = sshpkt_put_u32(ssh, reason)) != 0 || (r = sshpkt_put_cstring(ssh, errmsg ? errmsg : "open failed")) != 0 || (r = sshpkt_put_cstring(ssh, "")) != 0 || (r = sshpkt_send(ssh)) != 0) { sshpkt_fatal(ssh, r, "%s: send open failure", __func__); } } free(ctype); return 0; } static int server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp) { struct sshbuf *resp = NULL; struct sshbuf *sigbuf = NULL; struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL; int r, ndx, kexsigtype, use_kexsigtype, success = 0; const u_char *blob; u_char *sig = 0; size_t blen, slen; if ((resp = sshbuf_new()) == NULL || (sigbuf = sshbuf_new()) == NULL) fatal("%s: sshbuf_new", __func__); kexsigtype = sshkey_type_plain( sshkey_type_from_name(ssh->kex->hostkey_alg)); while (ssh_packet_remaining(ssh) > 0) { sshkey_free(key); key = NULL; if ((r = sshpkt_get_string_direct(ssh, &blob, &blen)) != 0 || (r = sshkey_from_blob(blob, blen, &key)) != 0) { error("%s: couldn't parse key: %s", __func__, ssh_err(r)); goto out; } /* * Better check that this is actually one of our hostkeys * before attempting to sign anything with it. */ if ((ndx = ssh->kex->host_key_index(key, 1, ssh)) == -1) { error("%s: unknown host %s key", __func__, sshkey_type(key)); goto out; } /* * XXX refactor: make kex->sign just use an index rather * than passing in public and private keys */ if ((key_prv = get_hostkey_by_index(ndx)) == NULL && (key_pub = get_hostkey_public_by_index(ndx, ssh)) == NULL) { error("%s: can't retrieve hostkey %d", __func__, ndx); goto out; } sshbuf_reset(sigbuf); free(sig); sig = NULL; /* * For RSA keys, prefer to use the signature type negotiated * during KEX to the default (SHA1). */ use_kexsigtype = kexsigtype == KEY_RSA && sshkey_type_plain(key->type) == KEY_RSA; if ((r = sshbuf_put_cstring(sigbuf, "hostkeys-prove-00@openssh.com")) != 0 || (r = sshbuf_put_string(sigbuf, ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || (r = sshkey_puts(key, sigbuf)) != 0 || (r = ssh->kex->sign(ssh, key_prv, key_pub, &sig, &slen, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), use_kexsigtype ? ssh->kex->hostkey_alg : NULL)) != 0 || (r = sshbuf_put_string(resp, sig, slen)) != 0) { error("%s: couldn't prepare signature: %s", __func__, ssh_err(r)); goto out; } } /* Success */ *respp = resp; resp = NULL; /* don't free it */ success = 1; out: free(sig); sshbuf_free(resp); sshbuf_free(sigbuf); sshkey_free(key); return success; } static int server_input_global_request(int type, u_int32_t seq, struct ssh *ssh) { char *rtype = NULL; u_char want_reply = 0; int r, success = 0, allocated_listen_port = 0; u_int port = 0; struct sshbuf *resp = NULL; struct passwd *pw = the_authctxt->pw; struct Forward fwd; memset(&fwd, 0, sizeof(fwd)); if (pw == NULL || !the_authctxt->valid) fatal("%s: no/invalid user", __func__); if ((r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || (r = sshpkt_get_u8(ssh, &want_reply)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply); /* -R style forwarding */ if (strcmp(rtype, "tcpip-forward") == 0) { if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &port)) != 0) sshpkt_fatal(ssh, r, "%s: parse tcpip-forward", __func__); debug("%s: tcpip-forward listen %s port %u", __func__, fwd.listen_host, port); if (port <= INT_MAX) fwd.listen_port = (int)port; /* check permissions */ if (port > INT_MAX || (options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || !auth_opts->permit_port_forwarding_flag || options.disable_forwarding || (!want_reply && fwd.listen_port == 0) || (fwd.listen_port != 0 && !bind_permitted(fwd.listen_port, pw->pw_uid))) { success = 0; ssh_packet_send_debug(ssh, "Server has disabled port forwarding."); } else { /* Start listening on the port */ success = channel_setup_remote_fwd_listener(ssh, &fwd, &allocated_listen_port, &options.fwd_opts); } if ((resp = sshbuf_new()) == NULL) fatal("%s: sshbuf_new", __func__); if (allocated_listen_port != 0 && (r = sshbuf_put_u32(resp, allocated_listen_port)) != 0) fatal("%s: sshbuf_put_u32: %s", __func__, ssh_err(r)); } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) { if ((r = sshpkt_get_cstring(ssh, &fwd.listen_host, NULL)) != 0 || (r = sshpkt_get_u32(ssh, &port)) != 0) sshpkt_fatal(ssh, r, "%s: parse cancel-tcpip-forward", __func__); debug("%s: cancel-tcpip-forward addr %s port %d", __func__, fwd.listen_host, port); if (port <= INT_MAX) { fwd.listen_port = (int)port; success = channel_cancel_rport_listener(ssh, &fwd); } } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0) sshpkt_fatal(ssh, r, "%s: parse streamlocal-forward@openssh.com", __func__); debug("%s: streamlocal-forward listen path %s", __func__, fwd.listen_path); /* check permissions */ if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 || !auth_opts->permit_port_forwarding_flag || options.disable_forwarding || (pw->pw_uid != 0 && !use_privsep)) { success = 0; ssh_packet_send_debug(ssh, "Server has disabled " "streamlocal forwarding."); } else { /* Start listening on the socket */ success = channel_setup_remote_fwd_listener(ssh, &fwd, NULL, &options.fwd_opts); } } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { if ((r = sshpkt_get_cstring(ssh, &fwd.listen_path, NULL)) != 0) sshpkt_fatal(ssh, r, "%s: parse cancel-streamlocal-forward@openssh.com", __func__); debug("%s: cancel-streamlocal-forward path %s", __func__, fwd.listen_path); success = channel_cancel_rport_listener(ssh, &fwd); } else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) { no_more_sessions = 1; success = 1; } else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) { success = server_input_hostkeys_prove(ssh, &resp); } /* XXX sshpkt_get_end() */ if (want_reply) { if ((r = sshpkt_start(ssh, success ? SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE)) != 0 || (success && resp != NULL && (r = sshpkt_putb(ssh, resp)) != 0) || (r = sshpkt_send(ssh)) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: send reply", __func__); } free(fwd.listen_host); free(fwd.listen_path); free(rtype); sshbuf_free(resp); return 0; } static int server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) { Channel *c; int r, success = 0; char *rtype = NULL; u_char want_reply = 0; u_int id = 0; if ((r = sshpkt_get_u32(ssh, &id)) != 0 || (r = sshpkt_get_cstring(ssh, &rtype, NULL)) != 0 || (r = sshpkt_get_u8(ssh, &want_reply)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); debug("server_input_channel_req: channel %u request %s reply %d", id, rtype, want_reply); if (id >= INT_MAX || (c = channel_lookup(ssh, (int)id)) == NULL) { ssh_packet_disconnect(ssh, "%s: unknown channel %d", __func__, id); } if (!strcmp(rtype, "eow@openssh.com")) { if ((r = sshpkt_get_end(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: parse packet", __func__); chan_rcvd_eow(ssh, c); } else if ((c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0) success = session_input_channel_req(ssh, c, rtype); if (want_reply && !(c->flags & CHAN_CLOSE_SENT)) { if (!c->have_remote_id) fatal("%s: channel %d: no remote_id", __func__, c->self); if ((r = sshpkt_start(ssh, success ? SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE)) != 0 || (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 || (r = sshpkt_send(ssh)) != 0) sshpkt_fatal(ssh, r, "%s: send reply", __func__); } free(rtype); return 0; } static void server_init_dispatch(struct ssh *ssh) { debug("server_init_dispatch"); ssh_dispatch_init(ssh, &dispatch_protocol_error); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_DATA, &channel_input_data); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); ssh_dispatch_set(ssh, SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); /* client_alive */ ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); ssh_dispatch_set(ssh, SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); ssh_dispatch_set(ssh, SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); /* rekeying */ ssh_dispatch_set(ssh, SSH2_MSG_KEXINIT, &kex_input_kexinit); }