| /* $OpenBSD: serverloop.c,v 1.204 2018/02/11 21:16:56 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 "buffer.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 "key.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 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; |
| |
| /* |
| * 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("notify_done: reading"); |
| } |
| |
| /*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."); |
| |
| mysignal(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("server_request_direct_tcpip: originator %s port %d, target %s " |
| "port %d", originator, originator_port, target, target_port); |
| |
| /* XXX fine grained permissions */ |
| if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 && |
| !no_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("server_input_global_request: no/invalid user"); |
| |
| target = packet_get_string(NULL); |
| originator = packet_get_string(NULL); |
| originator_port = packet_get_int(); |
| packet_check_eom(); |
| |
| debug("server_request_direct_streamlocal: originator %s port %d, target %s", |
| originator, originator_port, target); |
| |
| /* XXX fine grained permissions */ |
| if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 && |
| !no_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; |
| int 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 (forced_tun_device != -1) { |
| if (tun != SSH_TUNID_ANY && forced_tun_device != tun) |
| goto done; |
| tun = forced_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("server_input_channel_open: ctype %s rchan %d win %d max %d", |
| 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("server_input_channel_open: confirm %s", 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("server_input_channel_open: failure %s", 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("server_input_global_request: no/invalid user"); |
| |
| rtype = packet_get_string(NULL); |
| want_reply = packet_get_char(); |
| debug("server_input_global_request: rtype %s want_reply %d", 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("server_input_global_request: tcpip-forward listen %s port %d", |
| fwd.listen_host, fwd.listen_port); |
| |
| /* check permissions */ |
| if ((options.allow_tcp_forwarding & FORWARD_REMOTE) == 0 || |
| no_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("server_input_global_request: streamlocal-forward listen path %s", |
| fwd.listen_path); |
| |
| /* check permissions */ |
| if ((options.allow_streamlocal_forwarding & FORWARD_REMOTE) == 0 |
| || no_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); |
| } |