diff options
Diffstat (limited to '')
-rw-r--r-- | serverloop.c | 921 |
1 files changed, 921 insertions, 0 deletions
diff --git a/serverloop.c b/serverloop.c new file mode 100644 index 0000000..7be83e2 --- /dev/null +++ b/serverloop.c @@ -0,0 +1,921 @@ +/* $OpenBSD: serverloop.c,v 1.209 2018/07/27 05:13:02 dtucker Exp $ */ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, 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 "includes.h" + +#include <sys/types.h> +#include <sys/wait.h> +#include <sys/socket.h> +#ifdef HAVE_SYS_TIME_H +# include <sys/time.h> +#endif + +#include <netinet/in.h> + +#include <errno.h> +#include <fcntl.h> +#include <pwd.h> +#include <signal.h> +#include <string.h> +#include <termios.h> +#include <unistd.h> +#include <stdarg.h> + +#include "openbsd-compat/sys-queue.h" +#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(void); + +/* 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) < 0) { + 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) +{ + int channel_id; + char remote_id[512]; + + /* timeout, check to see how many we have had */ + if (packet_inc_alive_timeouts() > 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) { + packet_start(SSH2_MSG_GLOBAL_REQUEST); + packet_put_cstring("keepalive@openssh.com"); + packet_put_char(1); /* boolean: want reply */ + } else { + channel_request_start(ssh, channel_id, + "keepalive@openssh.com", 1); + } + packet_send(); +} + +/* + * 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; + 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; + + client_alive_scheduled = 1; + if (max_time_ms == 0 || max_time_ms > keepalive_ms) + max_time_ms = keepalive_ms; + } + +#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 (packet_have_data_to_write()) + 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 && packet_not_very_much_data_to_write()) + 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 (ret == 0) { /* timeout */ + client_alive_check(ssh); + } else if (FD_ISSET(connection_in, *readsetp)) { + last_client_time = now; + } else if (last_client_time != 0 && last_client_time + + options.client_alive_interval <= now) { + client_alive_check(ssh); + 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 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 < 0) { + if (errno != EINTR && errno != EAGAIN && + errno != EWOULDBLOCK) { + 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. */ + packet_process_incoming(buf, len); + } + } + return 0; +} + +/* + * Sends data from internal buffers to client program stdin. + */ +static void +process_output(fd_set *writeset, int connection_out) +{ + /* Send any buffered packet data to the client. */ + if (FD_ISSET(connection_out, writeset)) + packet_write_poll(); +} + +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 < 0 && 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."); + + signal(SIGCHLD, sigchld_handler); + child_terminated = 0; + connection_in = packet_get_connection_in(); + connection_out = packet_get_connection_out(); + + if (!use_privsep) { + signal(SIGTERM, sigterm_handler); + signal(SIGINT, sigterm_handler); + signal(SIGQUIT, sigterm_handler); + } + + notify_setup(); + + max_fd = MAXIMUM(connection_in, connection_out); + max_fd = MAXIMUM(max_fd, notify_pipe[0]); + + server_init_dispatch(); + + for (;;) { + process_buffered_input_packets(ssh); + + if (!ssh_packet_is_rekeying(ssh) && + packet_not_very_much_data_to_write()) + channel_output_poll(ssh); + if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh)) + rekey_timeout_ms = packet_get_rekey_timeout() * 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(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. + */ + packet_set_alive_timeouts(0); + return 0; +} + +static Channel * +server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg) +{ + Channel *c = NULL; + char *target, *originator; + u_short target_port, originator_port; + + target = packet_get_string(NULL); + target_port = packet_get_int(); + originator = packet_get_string(NULL); + originator_port = packet_get_int(); + packet_check_eom(); + + debug("%s: originator %s port %d, target %s port %d", __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; + } + + free(originator); + free(target); + + return c; +} + +static Channel * +server_request_direct_streamlocal(struct ssh *ssh) +{ + Channel *c = NULL; + char *target, *originator; + u_short originator_port; + struct passwd *pw = the_authctxt->pw; + + if (pw == NULL || !the_authctxt->valid) + fatal("%s: no/invalid user", __func__); + + target = packet_get_string(NULL); + originator = packet_get_string(NULL); + originator_port = packet_get_int(); + packet_check_eom(); + + 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); + } + + free(originator); + free(target); + + return c; +} + +static Channel * +server_request_tun(struct ssh *ssh) +{ + Channel *c = NULL; + int mode, tun, sock; + char *tmp, *ifname = NULL; + + mode = packet_get_int(); + switch (mode) { + case SSH_TUNMODE_POINTOPOINT: + case SSH_TUNMODE_ETHERNET: + break; + default: + packet_send_debug("Unsupported tunnel device mode."); + return NULL; + } + if ((options.permit_tun & mode) == 0) { + packet_send_debug("Server has rejected tunnel device " + "forwarding"); + return NULL; + } + + tun = packet_get_int(); + if (auth_opts->force_tun_device != -1) { + if (tun != SSH_TUNID_ANY && auth_opts->force_tun_device != 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; +#if defined(SSH_TUN_FILTER) + if (mode == SSH_TUNMODE_POINTOPOINT) + channel_register_filter(ssh, c->self, sys_tun_infilter, + sys_tun_outfilter, NULL, NULL); +#endif + + /* + * 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) + packet_send_debug("Failed to open the tunnel device."); + return c; +} + +static Channel * +server_request_session(struct ssh *ssh) +{ + Channel *c; + + debug("input_session_request"); + packet_check_eom(); + + if (no_more_sessions) { + packet_disconnect("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; + const char *errmsg = NULL; + int rchan, reason = SSH2_OPEN_CONNECT_FAILED; + u_int rmaxpack, rwindow, len; + + ctype = packet_get_string(&len); + rchan = packet_get_int(); + rwindow = packet_get_int(); + rmaxpack = packet_get_int(); + + debug("%s: ctype %s rchan %d win %d max %d", __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) { + packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); + packet_put_int(c->remote_id); + packet_put_int(c->self); + packet_put_int(c->local_window); + packet_put_int(c->local_maxpacket); + packet_send(); + } + } else { + debug("%s: failure %s", __func__, ctype); + packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(rchan); + packet_put_int(reason); + packet_put_cstring(errmsg ? errmsg : "open failed"); + packet_put_cstring(""); + packet_send(); + } + 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(key_prv, key_pub, &sig, &slen, + sshbuf_ptr(sigbuf), sshbuf_len(sigbuf), + use_kexsigtype ? ssh->kex->hostkey_alg : NULL, 0)) != 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; + int want_reply; + int r, success = 0, allocated_listen_port = 0; + struct sshbuf *resp = NULL; + struct passwd *pw = the_authctxt->pw; + + if (pw == NULL || !the_authctxt->valid) + fatal("%s: no/invalid user", __func__); + + rtype = packet_get_string(NULL); + want_reply = packet_get_char(); + debug("%s: rtype %s want_reply %d", __func__, rtype, want_reply); + + /* -R style forwarding */ + if (strcmp(rtype, "tcpip-forward") == 0) { + struct Forward fwd; + + memset(&fwd, 0, sizeof(fwd)); + fwd.listen_host = packet_get_string(NULL); + fwd.listen_port = (u_short)packet_get_int(); + debug("%s: tcpip-forward listen %s port %d", __func__, + fwd.listen_host, fwd.listen_port); + + /* check permissions */ + if ((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; + packet_send_debug("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); + } + free(fwd.listen_host); + 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) { + struct Forward fwd; + + memset(&fwd, 0, sizeof(fwd)); + fwd.listen_host = packet_get_string(NULL); + fwd.listen_port = (u_short)packet_get_int(); + debug("%s: cancel-tcpip-forward addr %s port %d", __func__, + fwd.listen_host, fwd.listen_port); + + success = channel_cancel_rport_listener(ssh, &fwd); + free(fwd.listen_host); + } else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) { + struct Forward fwd; + + memset(&fwd, 0, sizeof(fwd)); + fwd.listen_path = packet_get_string(NULL); + 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; + packet_send_debug("Server has disabled " + "streamlocal forwarding."); + } else { + /* Start listening on the socket */ + success = channel_setup_remote_fwd_listener(ssh, + &fwd, NULL, &options.fwd_opts); + } + free(fwd.listen_path); + } else if (strcmp(rtype, "cancel-streamlocal-forward@openssh.com") == 0) { + struct Forward fwd; + + memset(&fwd, 0, sizeof(fwd)); + fwd.listen_path = packet_get_string(NULL); + debug("%s: cancel-streamlocal-forward path %s", __func__, + fwd.listen_path); + + success = channel_cancel_rport_listener(ssh, &fwd); + free(fwd.listen_path); + } 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); + } + if (want_reply) { + packet_start(success ? + SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); + if (success && resp != NULL) + ssh_packet_put_raw(ssh, sshbuf_ptr(resp), + sshbuf_len(resp)); + packet_send(); + packet_write_wait(); + } + 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 id, reply, success = 0; + char *rtype; + + id = packet_get_int(); + rtype = packet_get_string(NULL); + reply = packet_get_char(); + + debug("server_input_channel_req: channel %d request %s reply %d", + id, rtype, reply); + + if ((c = channel_lookup(ssh, id)) == NULL) + packet_disconnect("server_input_channel_req: " + "unknown channel %d", id); + if (!strcmp(rtype, "eow@openssh.com")) { + packet_check_eom(); + 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 (reply && !(c->flags & CHAN_CLOSE_SENT)) { + if (!c->have_remote_id) + fatal("%s: channel %d: no remote_id", + __func__, c->self); + packet_start(success ? + SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); + packet_put_int(c->remote_id); + packet_send(); + } + free(rtype); + return 0; +} + +static void +server_init_dispatch(void) +{ + debug("server_init_dispatch"); + dispatch_init(&dispatch_protocol_error); + dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); + dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); + dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); + dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); + dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); + dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); + dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); + dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); + dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); + dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); + /* client_alive */ + dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &server_input_keep_alive); + dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive); + dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive); + dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive); + /* rekeying */ + dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); +} |