/* $OpenBSD: clientloop.c,v 1.305 2017/09/19 04:24:22 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * The main loop for the interactive session (client side). * * 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". * * * Copyright (c) 1999 Theo de Raadt. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * * SSH2 support added by Markus Friedl. * Copyright (c) 1999, 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 #include #include "xmalloc.h" #include "ssh.h" #include "ssh2.h" #include "packet.h" #include "buffer.h" #include "compat.h" #include "channels.h" #include "dispatch.h" #include "key.h" #include "cipher.h" #include "kex.h" #include "myproposal.h" #include "log.h" #include "misc.h" #include "readconf.h" #include "clientloop.h" #include "sshconnect.h" #include "authfd.h" #include "atomicio.h" #include "sshpty.h" #include "match.h" #include "msg.h" #include "ssherr.h" #include "hostfile.h" /* import options */ extern Options options; /* Flag indicating that stdin should be redirected from /dev/null. */ extern int stdin_null_flag; /* Flag indicating that no shell has been requested */ extern int no_shell_flag; /* Flag indicating that ssh should daemonise after authentication is complete */ extern int fork_after_authentication_flag; /* Control socket */ extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */ /* * Name of the host we are connecting to. This is the name given on the * command line, or the HostName specified for the user-supplied name in a * configuration file. */ extern char *host; /* * Flag to indicate that we have received a window change signal which has * not yet been processed. This will cause a message indicating the new * window size to be sent to the server a little later. This is volatile * because this is updated in a signal handler. */ static volatile sig_atomic_t received_window_change_signal = 0; static volatile sig_atomic_t received_signal = 0; /* Flag indicating whether the user's terminal is in non-blocking mode. */ static int in_non_blocking_mode = 0; /* Time when backgrounded control master using ControlPersist should exit */ static time_t control_persist_exit_time = 0; /* Common data for the client loop code. */ volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */ static int last_was_cr; /* Last character was a newline. */ static int exit_status; /* Used to store the command exit status. */ static Buffer stderr_buffer; /* Used for final exit message. */ static int connection_in; /* Connection to server (input). */ static int connection_out; /* Connection to server (output). */ static int need_rekeying; /* Set to non-zero if rekeying is requested. */ static int session_closed; /* In SSH2: login session closed. */ static u_int x11_refuse_time; /* If >0, refuse x11 opens after this time. */ static void client_init_dispatch(void); int session_ident = -1; /* Track escape per proto2 channel */ struct escape_filter_ctx { int escape_pending; int escape_char; }; /* Context for channel confirmation replies */ struct channel_reply_ctx { const char *request_type; int id; enum confirm_action action; }; /* Global request success/failure callbacks */ /* XXX move to struct ssh? */ struct global_confirm { TAILQ_ENTRY(global_confirm) entry; global_confirm_cb *cb; void *ctx; int ref_count; }; TAILQ_HEAD(global_confirms, global_confirm); static struct global_confirms global_confirms = TAILQ_HEAD_INITIALIZER(global_confirms); void ssh_process_session2_setup(int, int, int, Buffer *); /* Restores stdin to blocking mode. */ static void leave_non_blocking(void) { if (in_non_blocking_mode) { unset_nonblock(fileno(stdin)); in_non_blocking_mode = 0; } } /* * Signal handler for the window change signal (SIGWINCH). This just sets a * flag indicating that the window has changed. */ /*ARGSUSED */ static void window_change_handler(int sig) { received_window_change_signal = 1; signal(SIGWINCH, window_change_handler); } /* * Signal handler for signals that cause the program to terminate. These * signals must be trapped to restore terminal modes. */ /*ARGSUSED */ static void signal_handler(int sig) { received_signal = sig; quit_pending = 1; } /* * Returns current time in seconds from Jan 1, 1970 with the maximum * available resolution. */ static double get_current_time(void) { struct timeval tv; gettimeofday(&tv, NULL); return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0; } /* * Sets control_persist_exit_time to the absolute time when the * backgrounded control master should exit due to expiry of the * ControlPersist timeout. Sets it to 0 if we are not a backgrounded * control master process, or if there is no ControlPersist timeout. */ static void set_control_persist_exit_time(struct ssh *ssh) { if (muxserver_sock == -1 || !options.control_persist || options.control_persist_timeout == 0) { /* not using a ControlPersist timeout */ control_persist_exit_time = 0; } else if (channel_still_open(ssh)) { /* some client connections are still open */ if (control_persist_exit_time > 0) debug2("%s: cancel scheduled exit", __func__); control_persist_exit_time = 0; } else if (control_persist_exit_time <= 0) { /* a client connection has recently closed */ control_persist_exit_time = monotime() + (time_t)options.control_persist_timeout; debug2("%s: schedule exit in %d seconds", __func__, options.control_persist_timeout); } /* else we are already counting down to the timeout */ } #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_" static int client_x11_display_valid(const char *display) { size_t i, dlen; if (display == NULL) return 0; dlen = strlen(display); for (i = 0; i < dlen; i++) { if (!isalnum((u_char)display[i]) && strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) { debug("Invalid character '%c' in DISPLAY", display[i]); return 0; } } return 1; } #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1" #define X11_TIMEOUT_SLACK 60 int client_x11_get_proto(struct ssh *ssh, const char *display, const char *xauth_path, u_int trusted, u_int timeout, char **_proto, char **_data) { char cmd[1024], line[512], xdisplay[512]; char xauthfile[PATH_MAX], xauthdir[PATH_MAX]; static char proto[512], data[512]; FILE *f; int got_data = 0, generated = 0, do_unlink = 0, r; struct stat st; u_int now, x11_timeout_real; *_proto = proto; *_data = data; proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0'; if (!client_x11_display_valid(display)) { if (display != NULL) logit("DISPLAY \"%s\" invalid; disabling X11 forwarding", display); return -1; } if (xauth_path != NULL && stat(xauth_path, &st) == -1) { debug("No xauth program."); xauth_path = NULL; } if (xauth_path != NULL) { /* * Handle FamilyLocal case where $DISPLAY does * not match an authorization entry. For this we * just try "xauth list unix:displaynum.screennum". * XXX: "localhost" match to determine FamilyLocal * is not perfect. */ if (strncmp(display, "localhost:", 10) == 0) { if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s", display + 10)) < 0 || (size_t)r >= sizeof(xdisplay)) { error("%s: display name too long", __func__); return -1; } display = xdisplay; } if (trusted == 0) { /* * Generate an untrusted X11 auth cookie. * * The authentication cookie should briefly outlive * ssh's willingness to forward X11 connections to * avoid nasty fail-open behaviour in the X server. */ mktemp_proto(xauthdir, sizeof(xauthdir)); if (mkdtemp(xauthdir) == NULL) { error("%s: mkdtemp: %s", __func__, strerror(errno)); return -1; } do_unlink = 1; if ((r = snprintf(xauthfile, sizeof(xauthfile), "%s/xauthfile", xauthdir)) < 0 || (size_t)r >= sizeof(xauthfile)) { error("%s: xauthfile path too long", __func__); unlink(xauthfile); rmdir(xauthdir); return -1; } if (timeout >= UINT_MAX - X11_TIMEOUT_SLACK) x11_timeout_real = UINT_MAX; else x11_timeout_real = timeout + X11_TIMEOUT_SLACK; if ((r = snprintf(cmd, sizeof(cmd), "%s -f %s generate %s " SSH_X11_PROTO " untrusted timeout %u 2>" _PATH_DEVNULL, xauth_path, xauthfile, display, x11_timeout_real)) < 0 || (size_t)r >= sizeof(cmd)) fatal("%s: cmd too long", __func__); debug2("%s: %s", __func__, cmd); if (x11_refuse_time == 0) { now = monotime() + 1; if (UINT_MAX - timeout < now) x11_refuse_time = UINT_MAX; else x11_refuse_time = now + timeout; channel_set_x11_refuse_time(ssh, x11_refuse_time); } if (system(cmd) == 0) generated = 1; } /* * When in untrusted mode, we read the cookie only if it was * successfully generated as an untrusted one in the step * above. */ if (trusted || generated) { snprintf(cmd, sizeof(cmd), "%s %s%s list %s 2>" _PATH_DEVNULL, xauth_path, generated ? "-f " : "" , generated ? xauthfile : "", display); debug2("x11_get_proto: %s", cmd); f = popen(cmd, "r"); if (f && fgets(line, sizeof(line), f) && sscanf(line, "%*s %511s %511s", proto, data) == 2) got_data = 1; if (f) pclose(f); } } if (do_unlink) { unlink(xauthfile); rmdir(xauthdir); } /* Don't fall back to fake X11 data for untrusted forwarding */ if (!trusted && !got_data) { error("Warning: untrusted X11 forwarding setup failed: " "xauth key data not generated"); return -1; } /* * If we didn't get authentication data, just make up some * data. The forwarding code will check the validity of the * response anyway, and substitute this data. The X11 * server, however, will ignore this fake data and use * whatever authentication mechanisms it was using otherwise * for the local connection. */ if (!got_data) { u_int8_t rnd[16]; u_int i; logit("Warning: No xauth data; " "using fake authentication data for X11 forwarding."); strlcpy(proto, SSH_X11_PROTO, sizeof proto); arc4random_buf(rnd, sizeof(rnd)); for (i = 0; i < sizeof(rnd); i++) { snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rnd[i]); } } return 0; } /* * Checks if the client window has changed, and sends a packet about it to * the server if so. The actual change is detected elsewhere (by a software * interrupt on Unix); this just checks the flag and sends a message if * appropriate. */ static void client_check_window_change(struct ssh *ssh) { if (!received_window_change_signal) return; /** XXX race */ received_window_change_signal = 0; debug2("%s: changed", __func__); channel_send_window_changes(ssh); } static int client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh) { struct global_confirm *gc; if ((gc = TAILQ_FIRST(&global_confirms)) == NULL) return 0; if (gc->cb != NULL) gc->cb(ssh, type, seq, gc->ctx); if (--gc->ref_count <= 0) { TAILQ_REMOVE(&global_confirms, gc, entry); explicit_bzero(gc, sizeof(*gc)); free(gc); } packet_set_alive_timeouts(0); return 0; } static void server_alive_check(void) { if (packet_inc_alive_timeouts() > options.server_alive_count_max) { logit("Timeout, server %s not responding.", host); cleanup_exit(255); } packet_start(SSH2_MSG_GLOBAL_REQUEST); packet_put_cstring("keepalive@openssh.com"); packet_put_char(1); /* boolean: want reply */ packet_send(); /* Insert an empty placeholder to maintain ordering */ client_register_global_confirm(NULL, NULL); } /* * Waits until the client can do something (some data becomes available on * one of the file descriptors). */ static void client_wait_until_can_do_something(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp, int *maxfdp, u_int *nallocp, int rekeying) { struct timeval tv, *tvp; int timeout_secs; time_t minwait_secs = 0, server_alive_time = 0, now = monotime(); int ret; /* Add any selections by the channel mechanism. */ channel_prepare_select(active_state, readsetp, writesetp, maxfdp, nallocp, &minwait_secs); /* channel_prepare_select could have closed the last channel */ if (session_closed && !channel_still_open(ssh) && !packet_have_data_to_write()) { /* clear mask since we did not call select() */ memset(*readsetp, 0, *nallocp); memset(*writesetp, 0, *nallocp); return; } FD_SET(connection_in, *readsetp); /* Select server connection if have data to write to the server. */ if (packet_have_data_to_write()) FD_SET(connection_out, *writesetp); /* * Wait for something to happen. This will suspend the process until * some selected descriptor can be read, written, or has some other * event pending, or a timeout expires. */ timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */ if (options.server_alive_interval > 0) { timeout_secs = options.server_alive_interval; server_alive_time = now + options.server_alive_interval; } if (options.rekey_interval > 0 && !rekeying) timeout_secs = MINIMUM(timeout_secs, packet_get_rekey_timeout()); set_control_persist_exit_time(ssh); if (control_persist_exit_time > 0) { timeout_secs = MINIMUM(timeout_secs, control_persist_exit_time - now); if (timeout_secs < 0) timeout_secs = 0; } if (minwait_secs != 0) timeout_secs = MINIMUM(timeout_secs, (int)minwait_secs); if (timeout_secs == INT_MAX) tvp = NULL; else { tv.tv_sec = timeout_secs; tv.tv_usec = 0; tvp = &tv; } ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); if (ret < 0) { char buf[100]; /* * We have to clear the select masks, because we return. * We have to return, because the mainloop checks for the flags * set by the signal handlers. */ memset(*readsetp, 0, *nallocp); memset(*writesetp, 0, *nallocp); if (errno == EINTR) return; /* Note: we might still have data in the buffers. */ snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno)); buffer_append(&stderr_buffer, buf, strlen(buf)); quit_pending = 1; } else if (ret == 0) { /* * Timeout. Could have been either keepalive or rekeying. * Keepalive we check here, rekeying is checked in clientloop. */ if (server_alive_time != 0 && server_alive_time <= monotime()) server_alive_check(); } } static void client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr) { /* Flush stdout and stderr buffers. */ if (buffer_len(bout) > 0) atomicio(vwrite, fileno(stdout), buffer_ptr(bout), buffer_len(bout)); if (buffer_len(berr) > 0) atomicio(vwrite, fileno(stderr), buffer_ptr(berr), buffer_len(berr)); leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); sshbuf_reset(bin); sshbuf_reset(bout); sshbuf_reset(berr); /* Send the suspend signal to the program itself. */ kill(getpid(), SIGTSTP); /* Reset window sizes in case they have changed */ received_window_change_signal = 1; enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); } static void client_process_net_input(fd_set *readset) { int len; char buf[8192]; /* * Read input from the server, and add any such data to the buffer of * the packet subsystem. */ if (FD_ISSET(connection_in, readset)) { /* Read as much as possible. */ len = read(connection_in, buf, sizeof(buf)); if (len == 0) { /* * Received EOF. The remote host has closed the * connection. */ snprintf(buf, sizeof buf, "Connection to %.300s closed by remote host.\r\n", host); buffer_append(&stderr_buffer, buf, strlen(buf)); quit_pending = 1; return; } /* * There is a kernel bug on Solaris that causes select to * sometimes wake up even though there is no data available. */ if (len < 0 && (errno == EAGAIN || errno == EINTR)) len = 0; if (len < 0) { /* * An error has encountered. Perhaps there is a * network problem. */ snprintf(buf, sizeof buf, "Read from remote host %.300s: %.100s\r\n", host, strerror(errno)); buffer_append(&stderr_buffer, buf, strlen(buf)); quit_pending = 1; return; } packet_process_incoming(buf, len); } } static void client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx) { struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx; char errmsg[256]; int tochan; /* * If a TTY was explicitly requested, then a failure to allocate * one is fatal. */ if (cr->action == CONFIRM_TTY && (options.request_tty == REQUEST_TTY_FORCE || options.request_tty == REQUEST_TTY_YES)) cr->action = CONFIRM_CLOSE; /* XXX supress on mux _client_ quietmode */ tochan = options.log_level >= SYSLOG_LEVEL_ERROR && c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE; if (type == SSH2_MSG_CHANNEL_SUCCESS) { debug2("%s request accepted on channel %d", cr->request_type, c->self); } else if (type == SSH2_MSG_CHANNEL_FAILURE) { if (tochan) { snprintf(errmsg, sizeof(errmsg), "%s request failed\r\n", cr->request_type); } else { snprintf(errmsg, sizeof(errmsg), "%s request failed on channel %d", cr->request_type, c->self); } /* If error occurred on primary session channel, then exit */ if (cr->action == CONFIRM_CLOSE && c->self == session_ident) fatal("%s", errmsg); /* * If error occurred on mux client, append to * their stderr. */ if (tochan) { buffer_append(c->extended, errmsg, strlen(errmsg)); } else error("%s", errmsg); if (cr->action == CONFIRM_TTY) { /* * If a TTY allocation error occurred, then arrange * for the correct TTY to leave raw mode. */ if (c->self == session_ident) leave_raw_mode(0); else mux_tty_alloc_failed(ssh, c); } else if (cr->action == CONFIRM_CLOSE) { chan_read_failed(ssh, c); chan_write_failed(ssh, c); } } free(cr); } static void client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx) { free(ctx); } void client_expect_confirm(struct ssh *ssh, int id, const char *request, enum confirm_action action) { struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr)); cr->request_type = request; cr->action = action; channel_register_status_confirm(ssh, id, client_status_confirm, client_abandon_status_confirm, cr); } void client_register_global_confirm(global_confirm_cb *cb, void *ctx) { struct global_confirm *gc, *last_gc; /* Coalesce identical callbacks */ last_gc = TAILQ_LAST(&global_confirms, global_confirms); if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) { if (++last_gc->ref_count >= INT_MAX) fatal("%s: last_gc->ref_count = %d", __func__, last_gc->ref_count); return; } gc = xcalloc(1, sizeof(*gc)); gc->cb = cb; gc->ctx = ctx; gc->ref_count = 1; TAILQ_INSERT_TAIL(&global_confirms, gc, entry); } static void process_cmdline(struct ssh *ssh) { void (*handler)(int); char *s, *cmd; int ok, delete = 0, local = 0, remote = 0, dynamic = 0; struct Forward fwd; memset(&fwd, 0, sizeof(fwd)); leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); handler = signal(SIGINT, SIG_IGN); cmd = s = read_passphrase("\r\nssh> ", RP_ECHO); if (s == NULL) goto out; while (isspace((u_char)*s)) s++; if (*s == '-') s++; /* Skip cmdline '-', if any */ if (*s == '\0') goto out; if (*s == 'h' || *s == 'H' || *s == '?') { logit("Commands:"); logit(" -L[bind_address:]port:host:hostport " "Request local forward"); logit(" -R[bind_address:]port:host:hostport " "Request remote forward"); logit(" -D[bind_address:]port " "Request dynamic forward"); logit(" -KL[bind_address:]port " "Cancel local forward"); logit(" -KR[bind_address:]port " "Cancel remote forward"); logit(" -KD[bind_address:]port " "Cancel dynamic forward"); if (!options.permit_local_command) goto out; logit(" !args " "Execute local command"); goto out; } if (*s == '!' && options.permit_local_command) { s++; ssh_local_cmd(s); goto out; } if (*s == 'K') { delete = 1; s++; } if (*s == 'L') local = 1; else if (*s == 'R') remote = 1; else if (*s == 'D') dynamic = 1; else { logit("Invalid command."); goto out; } while (isspace((u_char)*++s)) ; /* XXX update list of forwards in options */ if (delete) { /* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */ if (!parse_forward(&fwd, s, 1, 0)) { logit("Bad forwarding close specification."); goto out; } if (remote) ok = channel_request_rforward_cancel(ssh, &fwd) == 0; else if (dynamic) ok = channel_cancel_lport_listener(ssh, &fwd, 0, &options.fwd_opts) > 0; else ok = channel_cancel_lport_listener(ssh, &fwd, CHANNEL_CANCEL_PORT_STATIC, &options.fwd_opts) > 0; if (!ok) { logit("Unknown port forwarding."); goto out; } logit("Canceled forwarding."); } else { if (!parse_forward(&fwd, s, dynamic, remote)) { logit("Bad forwarding specification."); goto out; } if (local || dynamic) { if (!channel_setup_local_fwd_listener(ssh, &fwd, &options.fwd_opts)) { logit("Port forwarding failed."); goto out; } } else { if (channel_request_remote_forwarding(ssh, &fwd) < 0) { logit("Port forwarding failed."); goto out; } } logit("Forwarding port."); } out: signal(SIGINT, handler); enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); free(cmd); free(fwd.listen_host); free(fwd.listen_path); free(fwd.connect_host); free(fwd.connect_path); } /* reasons to suppress output of an escape command in help output */ #define SUPPRESS_NEVER 0 /* never suppress, always show */ #define SUPPRESS_MUXCLIENT 1 /* don't show in mux client sessions */ #define SUPPRESS_MUXMASTER 2 /* don't show in mux master sessions */ #define SUPPRESS_SYSLOG 4 /* don't show when logging to syslog */ struct escape_help_text { const char *cmd; const char *text; unsigned int flags; }; static struct escape_help_text esc_txt[] = { {".", "terminate session", SUPPRESS_MUXMASTER}, {".", "terminate connection (and any multiplexed sessions)", SUPPRESS_MUXCLIENT}, {"B", "send a BREAK to the remote system", SUPPRESS_NEVER}, {"C", "open a command line", SUPPRESS_MUXCLIENT}, {"R", "request rekey", SUPPRESS_NEVER}, {"V/v", "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT}, {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT}, {"#", "list forwarded connections", SUPPRESS_NEVER}, {"&", "background ssh (when waiting for connections to terminate)", SUPPRESS_MUXCLIENT}, {"?", "this message", SUPPRESS_NEVER}, }; static void print_escape_help(Buffer *b, int escape_char, int mux_client, int using_stderr) { unsigned int i, suppress_flags; char string[1024]; snprintf(string, sizeof string, "%c?\r\n" "Supported escape sequences:\r\n", escape_char); buffer_append(b, string, strlen(string)); suppress_flags = (mux_client ? SUPPRESS_MUXCLIENT : 0) | (mux_client ? 0 : SUPPRESS_MUXMASTER) | (using_stderr ? 0 : SUPPRESS_SYSLOG); for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) { if (esc_txt[i].flags & suppress_flags) continue; snprintf(string, sizeof string, " %c%-3s - %s\r\n", escape_char, esc_txt[i].cmd, esc_txt[i].text); buffer_append(b, string, strlen(string)); } snprintf(string, sizeof string, " %c%c - send the escape character by typing it twice\r\n" "(Note that escapes are only recognized immediately after " "newline.)\r\n", escape_char, escape_char); buffer_append(b, string, strlen(string)); } /* * Process the characters one by one. */ static int process_escapes(struct ssh *ssh, Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, char *buf, int len) { char string[1024]; pid_t pid; int bytes = 0; u_int i; u_char ch; char *s; struct escape_filter_ctx *efc = c->filter_ctx == NULL ? NULL : (struct escape_filter_ctx *)c->filter_ctx; if (c->filter_ctx == NULL) return 0; if (len <= 0) return (0); for (i = 0; i < (u_int)len; i++) { /* Get one character at a time. */ ch = buf[i]; if (efc->escape_pending) { /* We have previously seen an escape character. */ /* Clear the flag now. */ efc->escape_pending = 0; /* Process the escaped character. */ switch (ch) { case '.': /* Terminate the connection. */ snprintf(string, sizeof string, "%c.\r\n", efc->escape_char); buffer_append(berr, string, strlen(string)); if (c && c->ctl_chan != -1) { chan_read_failed(ssh, c); chan_write_failed(ssh, c); if (c->detach_user) { c->detach_user(ssh, c->self, NULL); } c->type = SSH_CHANNEL_ABANDONED; buffer_clear(c->input); chan_ibuf_empty(ssh, c); return 0; } else quit_pending = 1; return -1; case 'Z' - 64: /* XXX support this for mux clients */ if (c && c->ctl_chan != -1) { char b[16]; noescape: if (ch == 'Z' - 64) snprintf(b, sizeof b, "^Z"); else snprintf(b, sizeof b, "%c", ch); snprintf(string, sizeof string, "%c%s escape not available to " "multiplexed sessions\r\n", efc->escape_char, b); buffer_append(berr, string, strlen(string)); continue; } /* Suspend the program. Inform the user */ snprintf(string, sizeof string, "%c^Z [suspend ssh]\r\n", efc->escape_char); buffer_append(berr, string, strlen(string)); /* Restore terminal modes and suspend. */ client_suspend_self(bin, bout, berr); /* We have been continued. */ continue; case 'B': snprintf(string, sizeof string, "%cB\r\n", efc->escape_char); buffer_append(berr, string, strlen(string)); channel_request_start(ssh, c->self, "break", 0); packet_put_int(1000); packet_send(); continue; case 'R': if (datafellows & SSH_BUG_NOREKEY) logit("Server does not " "support re-keying"); else need_rekeying = 1; continue; case 'V': /* FALLTHROUGH */ case 'v': if (c && c->ctl_chan != -1) goto noescape; if (!log_is_on_stderr()) { snprintf(string, sizeof string, "%c%c [Logging to syslog]\r\n", efc->escape_char, ch); buffer_append(berr, string, strlen(string)); continue; } if (ch == 'V' && options.log_level > SYSLOG_LEVEL_QUIET) log_change_level(--options.log_level); if (ch == 'v' && options.log_level < SYSLOG_LEVEL_DEBUG3) log_change_level(++options.log_level); snprintf(string, sizeof string, "%c%c [LogLevel %s]\r\n", efc->escape_char, ch, log_level_name(options.log_level)); buffer_append(berr, string, strlen(string)); continue; case '&': if (c && c->ctl_chan != -1) goto noescape; /* * Detach the program (continue to serve * connections, but put in background and no * more new connections). */ /* Restore tty modes. */ leave_raw_mode( options.request_tty == REQUEST_TTY_FORCE); /* Stop listening for new connections. */ channel_stop_listening(ssh); snprintf(string, sizeof string, "%c& [backgrounded]\n", efc->escape_char); buffer_append(berr, string, strlen(string)); /* Fork into background. */ pid = fork(); if (pid < 0) { error("fork: %.100s", strerror(errno)); continue; } if (pid != 0) { /* This is the parent. */ /* The parent just exits. */ exit(0); } /* The child continues serving connections. */ buffer_append(bin, "\004", 1); /* fake EOF on stdin */ return -1; case '?': print_escape_help(berr, efc->escape_char, (c && c->ctl_chan != -1), log_is_on_stderr()); continue; case '#': snprintf(string, sizeof string, "%c#\r\n", efc->escape_char); buffer_append(berr, string, strlen(string)); s = channel_open_message(ssh); buffer_append(berr, s, strlen(s)); free(s); continue; case 'C': if (c && c->ctl_chan != -1) goto noescape; process_cmdline(ssh); continue; default: if (ch != efc->escape_char) { buffer_put_char(bin, efc->escape_char); bytes++; } /* Escaped characters fall through here */ break; } } else { /* * The previous character was not an escape char. * Check if this is an escape. */ if (last_was_cr && ch == efc->escape_char) { /* * It is. Set the flag and continue to * next character. */ efc->escape_pending = 1; continue; } } /* * Normal character. Record whether it was a newline, * and append it to the buffer. */ last_was_cr = (ch == '\r' || ch == '\n'); buffer_put_char(bin, ch); bytes++; } return bytes; } /* * Get packets from the connection input buffer, and process them as long as * there are packets available. * * Any unknown packets received during the actual * session cause the session to terminate. This is * intended to make debugging easier since no * confirmations are sent. Any compatible protocol * extensions must be negotiated during the * preparatory phase. */ static void client_process_buffered_input_packets(void) { ssh_dispatch_run_fatal(active_state, DISPATCH_NONBLOCK, &quit_pending); } /* scan buf[] for '~' before sending data to the peer */ /* Helper: allocate a new escape_filter_ctx and fill in its escape char */ void * client_new_escape_filter_ctx(int escape_char) { struct escape_filter_ctx *ret; ret = xcalloc(1, sizeof(*ret)); ret->escape_pending = 0; ret->escape_char = escape_char; return (void *)ret; } /* Free the escape filter context on channel free */ void client_filter_cleanup(struct ssh *ssh, int cid, void *ctx) { free(ctx); } int client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len) { if (c->extended_usage != CHAN_EXTENDED_WRITE) return 0; return process_escapes(ssh, c, c->input, c->output, c->extended, buf, len); } static void client_channel_closed(struct ssh *ssh, int id, void *arg) { channel_cancel_cleanup(ssh, id); session_closed = 1; leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); } /* * Implements the interactive session with the server. This is called after * the user has been authenticated, and a command has been started on the * remote host. If escape_char != SSH_ESCAPECHAR_NONE, it is the character * used as an escape character for terminating or suspending the session. */ int client_loop(struct ssh *ssh, int have_pty, int escape_char_arg, int ssh2_chan_id) { fd_set *readset = NULL, *writeset = NULL; double start_time, total_time; int r, max_fd = 0, max_fd2 = 0, len; u_int64_t ibytes, obytes; u_int nalloc = 0; char buf[100]; debug("Entering interactive session."); if (options.control_master && !option_clear_or_none(options.control_path)) { debug("pledge: id"); if (pledge("stdio rpath wpath cpath unix inet dns recvfd proc exec id tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); } else if (options.forward_x11 || options.permit_local_command) { debug("pledge: exec"); if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); } else if (options.update_hostkeys) { debug("pledge: filesystem full"); if (pledge("stdio rpath wpath cpath unix inet dns proc tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); } else if (!option_clear_or_none(options.proxy_command) || fork_after_authentication_flag) { debug("pledge: proc"); if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); } else { debug("pledge: network"); if (pledge("stdio unix inet dns proc tty", NULL) == -1) fatal("%s pledge(): %s", __func__, strerror(errno)); } start_time = get_current_time(); /* Initialize variables. */ last_was_cr = 1; exit_status = -1; connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); max_fd = MAXIMUM(connection_in, connection_out); quit_pending = 0; /* Initialize buffers. */ buffer_init(&stderr_buffer); client_init_dispatch(); /* * Set signal handlers, (e.g. to restore non-blocking mode) * but don't overwrite SIG_IGN, matches behaviour from rsh(1) */ if (signal(SIGHUP, SIG_IGN) != SIG_IGN) signal(SIGHUP, signal_handler); if (signal(SIGINT, SIG_IGN) != SIG_IGN) signal(SIGINT, signal_handler); if (signal(SIGQUIT, SIG_IGN) != SIG_IGN) signal(SIGQUIT, signal_handler); if (signal(SIGTERM, SIG_IGN) != SIG_IGN) signal(SIGTERM, signal_handler); signal(SIGWINCH, window_change_handler); if (have_pty) enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE); session_ident = ssh2_chan_id; if (session_ident != -1) { if (escape_char_arg != SSH_ESCAPECHAR_NONE) { channel_register_filter(ssh, session_ident, client_simple_escape_filter, NULL, client_filter_cleanup, client_new_escape_filter_ctx( escape_char_arg)); } channel_register_cleanup(ssh, session_ident, client_channel_closed, 0); } /* Main loop of the client for the interactive session mode. */ while (!quit_pending) { /* Process buffered packets sent by the server. */ client_process_buffered_input_packets(); if (session_closed && !channel_still_open(ssh)) break; if (ssh_packet_is_rekeying(ssh)) { debug("rekeying in progress"); } else if (need_rekeying) { /* manual rekey request */ debug("need rekeying"); if ((r = kex_start_rekex(ssh)) != 0) fatal("%s: kex_start_rekex: %s", __func__, ssh_err(r)); need_rekeying = 0; } else { /* * Make packets from buffered channel data, and * enqueue them for sending to the server. */ if (packet_not_very_much_data_to_write()) channel_output_poll(ssh); /* * Check if the window size has changed, and buffer a * message about it to the server if so. */ client_check_window_change(ssh); if (quit_pending) break; } /* * Wait until we have something to do (something becomes * available on one of the descriptors). */ max_fd2 = max_fd; client_wait_until_can_do_something(ssh, &readset, &writeset, &max_fd2, &nalloc, ssh_packet_is_rekeying(ssh)); if (quit_pending) break; /* Do channel operations unless rekeying in progress. */ if (!ssh_packet_is_rekeying(ssh)) channel_after_select(ssh, readset, writeset); /* Buffer input from the connection. */ client_process_net_input(readset); if (quit_pending) break; /* * Send as much buffered packet data as possible to the * sender. */ if (FD_ISSET(connection_out, writeset)) packet_write_poll(); /* * If we are a backgrounded control master, and the * timeout has expired without any active client * connections, then quit. */ if (control_persist_exit_time > 0) { if (monotime() >= control_persist_exit_time) { debug("ControlPersist timeout expired"); break; } } } free(readset); free(writeset); /* Terminate the session. */ /* Stop watching for window change. */ signal(SIGWINCH, SIG_DFL); packet_start(SSH2_MSG_DISCONNECT); packet_put_int(SSH2_DISCONNECT_BY_APPLICATION); packet_put_cstring("disconnected by user"); packet_put_cstring(""); /* language tag */ packet_send(); packet_write_wait(); channel_free_all(ssh); if (have_pty) leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); /* restore blocking io */ if (!isatty(fileno(stdin))) unset_nonblock(fileno(stdin)); if (!isatty(fileno(stdout))) unset_nonblock(fileno(stdout)); if (!isatty(fileno(stderr))) unset_nonblock(fileno(stderr)); /* * If there was no shell or command requested, there will be no remote * exit status to be returned. In that case, clear error code if the * connection was deliberately terminated at this end. */ if (no_shell_flag && received_signal == SIGTERM) { received_signal = 0; exit_status = 0; } if (received_signal) { verbose("Killed by signal %d.", (int) received_signal); cleanup_exit(0); } /* * In interactive mode (with pseudo tty) display a message indicating * that the connection has been closed. */ if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) { snprintf(buf, sizeof buf, "Connection to %.64s closed.\r\n", host); buffer_append(&stderr_buffer, buf, strlen(buf)); } /* Output any buffered data for stderr. */ if (buffer_len(&stderr_buffer) > 0) { len = atomicio(vwrite, fileno(stderr), buffer_ptr(&stderr_buffer), buffer_len(&stderr_buffer)); if (len < 0 || (u_int)len != buffer_len(&stderr_buffer)) error("Write failed flushing stderr buffer."); else buffer_consume(&stderr_buffer, len); } /* Clear and free any buffers. */ explicit_bzero(buf, sizeof(buf)); buffer_free(&stderr_buffer); /* Report bytes transferred, and transfer rates. */ total_time = get_current_time() - start_time; packet_get_bytes(&ibytes, &obytes); verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds", (unsigned long long)obytes, (unsigned long long)ibytes, total_time); if (total_time > 0) verbose("Bytes per second: sent %.1f, received %.1f", obytes / total_time, ibytes / total_time); /* Return the exit status of the program. */ debug("Exit status %d", exit_status); return exit_status; } /*********/ static Channel * client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type, int rchan, u_int rwindow, u_int rmaxpack) { Channel *c = NULL; struct sshbuf *b = NULL; char *listen_address, *originator_address; u_short listen_port, originator_port; int r; /* Get rest of the packet */ listen_address = packet_get_string(NULL); listen_port = packet_get_int(); originator_address = packet_get_string(NULL); originator_port = packet_get_int(); packet_check_eom(); debug("%s: listen %s port %d, originator %s port %d", __func__, listen_address, listen_port, originator_address, originator_port); c = channel_connect_by_listen_address(ssh, listen_address, listen_port, "forwarded-tcpip", originator_address); if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { if ((b = sshbuf_new()) == NULL) { error("%s: alloc reply", __func__); goto out; } /* reconstruct and send to muxclient */ if ((r = sshbuf_put_u8(b, 0)) != 0 || /* padlen */ (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 || (r = sshbuf_put_cstring(b, request_type)) != 0 || (r = sshbuf_put_u32(b, rchan)) != 0 || (r = sshbuf_put_u32(b, rwindow)) != 0 || (r = sshbuf_put_u32(b, rmaxpack)) != 0 || (r = sshbuf_put_cstring(b, listen_address)) != 0 || (r = sshbuf_put_u32(b, listen_port)) != 0 || (r = sshbuf_put_cstring(b, originator_address)) != 0 || (r = sshbuf_put_u32(b, originator_port)) != 0 || (r = sshbuf_put_stringb(c->output, b)) != 0) { error("%s: compose for muxclient %s", __func__, ssh_err(r)); goto out; } } out: sshbuf_free(b); free(originator_address); free(listen_address); return c; } static Channel * client_request_forwarded_streamlocal(struct ssh *ssh, const char *request_type, int rchan) { Channel *c = NULL; char *listen_path; /* Get the remote path. */ listen_path = packet_get_string(NULL); /* XXX: Skip reserved field for now. */ if (packet_get_string_ptr(NULL) == NULL) fatal("%s: packet_get_string_ptr failed", __func__); packet_check_eom(); debug("%s: %s", __func__, listen_path); c = channel_connect_by_listen_path(ssh, listen_path, "forwarded-streamlocal@openssh.com", "forwarded-streamlocal"); free(listen_path); return c; } static Channel * client_request_x11(struct ssh *ssh, const char *request_type, int rchan) { Channel *c = NULL; char *originator; u_short originator_port; int sock; if (!options.forward_x11) { error("Warning: ssh server tried X11 forwarding."); error("Warning: this is probably a break-in attempt by a " "malicious server."); return NULL; } if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) { verbose("Rejected X11 connection after ForwardX11Timeout " "expired"); return NULL; } originator = packet_get_string(NULL); if (datafellows & SSH_BUG_X11FWD) { debug2("buggy server: x11 request w/o originator_port"); originator_port = 0; } else { originator_port = packet_get_int(); } packet_check_eom(); /* XXX check permission */ debug("client_request_x11: request from %s %d", originator, originator_port); free(originator); sock = x11_connect_display(ssh); if (sock < 0) return NULL; c = channel_new(ssh, "x11", SSH_CHANNEL_X11_OPEN, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1); c->force_drain = 1; return c; } static Channel * client_request_agent(struct ssh *ssh, const char *request_type, int rchan) { Channel *c = NULL; int r, sock; if (!options.forward_agent) { error("Warning: ssh server tried agent forwarding."); error("Warning: this is probably a break-in attempt by a " "malicious server."); return NULL; } if ((r = ssh_get_authentication_socket(&sock)) != 0) { if (r != SSH_ERR_AGENT_NOT_PRESENT) debug("%s: ssh_get_authentication_socket: %s", __func__, ssh_err(r)); return NULL; } c = channel_new(ssh, "authentication agent connection", SSH_CHANNEL_OPEN, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "authentication agent connection", 1); c->force_drain = 1; return c; } int client_request_tun_fwd(struct ssh *ssh, int tun_mode, int local_tun, int remote_tun) { Channel *c; int fd; if (tun_mode == SSH_TUNMODE_NO) return 0; debug("Requesting tun unit %d in mode %d", local_tun, tun_mode); /* Open local tunnel device */ if ((fd = tun_open(local_tun, tun_mode)) == -1) { error("Tunnel device open failed."); return -1; } c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1); c->datagram = 1; packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring("tun@openssh.com"); packet_put_int(c->self); packet_put_int(c->local_window_max); packet_put_int(c->local_maxpacket); packet_put_int(tun_mode); packet_put_int(remote_tun); packet_send(); return 0; } /* XXXX move to generic input handler */ static int client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh) { Channel *c = NULL; char *ctype; int rchan; u_int rmaxpack, rwindow, len; ctype = packet_get_string(&len); rchan = packet_get_int(); rwindow = packet_get_int(); rmaxpack = packet_get_int(); debug("client_input_channel_open: ctype %s rchan %d win %d max %d", ctype, rchan, rwindow, rmaxpack); if (strcmp(ctype, "forwarded-tcpip") == 0) { c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow, rmaxpack); } else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) { c = client_request_forwarded_streamlocal(ssh, ctype, rchan); } else if (strcmp(ctype, "x11") == 0) { c = client_request_x11(ssh, ctype, rchan); } else if (strcmp(ctype, "auth-agent@openssh.com") == 0) { c = client_request_agent(ssh, ctype, rchan); } if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) { debug3("proxied to downstream: %s", ctype); } else if (c != NULL) { debug("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("failure %s", ctype); packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); packet_put_int(rchan); packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); if (!(datafellows & SSH_BUG_OPENFAILURE)) { packet_put_cstring("open failed"); packet_put_cstring(""); } packet_send(); } free(ctype); return 0; } static int client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh) { Channel *c = NULL; int exitval, id, reply, success = 0; char *rtype; id = packet_get_int(); c = channel_lookup(ssh, id); if (channel_proxy_upstream(c, type, seq, ssh)) return 0; rtype = packet_get_string(NULL); reply = packet_get_char(); debug("client_input_channel_req: channel %d rtype %s reply %d", id, rtype, reply); if (id == -1) { error("client_input_channel_req: request for channel -1"); } else if (c == NULL) { error("client_input_channel_req: channel %d: " "unknown channel", id); } else if (strcmp(rtype, "eow@openssh.com") == 0) { packet_check_eom(); chan_rcvd_eow(ssh, c); } else if (strcmp(rtype, "exit-status") == 0) { exitval = packet_get_int(); if (c->ctl_chan != -1) { mux_exit_message(ssh, c, exitval); success = 1; } else if (id == session_ident) { /* Record exit value of local session */ success = 1; exit_status = exitval; } else { /* Probably for a mux channel that has already closed */ debug("%s: no sink for exit-status on channel %d", __func__, id); } packet_check_eom(); } if (reply && c != NULL && !(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; } struct hostkeys_update_ctx { /* The hostname and (optionally) IP address string for the server */ char *host_str, *ip_str; /* * Keys received from the server and a flag for each indicating * whether they already exist in known_hosts. * keys_seen is filled in by hostkeys_find() and later (for new * keys) by client_global_hostkeys_private_confirm(). */ struct sshkey **keys; int *keys_seen; size_t nkeys, nnew; /* * Keys that are in known_hosts, but were not present in the update * from the server (i.e. scheduled to be deleted). * Filled in by hostkeys_find(). */ struct sshkey **old_keys; size_t nold; }; static void hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx) { size_t i; if (ctx == NULL) return; for (i = 0; i < ctx->nkeys; i++) sshkey_free(ctx->keys[i]); free(ctx->keys); free(ctx->keys_seen); for (i = 0; i < ctx->nold; i++) sshkey_free(ctx->old_keys[i]); free(ctx->old_keys); free(ctx->host_str); free(ctx->ip_str); free(ctx); } static int hostkeys_find(struct hostkey_foreach_line *l, void *_ctx) { struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; size_t i; struct sshkey **tmp; if (l->status != HKF_STATUS_MATCHED || l->key == NULL) return 0; /* Mark off keys we've already seen for this host */ for (i = 0; i < ctx->nkeys; i++) { if (sshkey_equal(l->key, ctx->keys[i])) { debug3("%s: found %s key at %s:%ld", __func__, sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum); ctx->keys_seen[i] = 1; return 0; } } /* This line contained a key that not offered by the server */ debug3("%s: deprecated %s key at %s:%ld", __func__, sshkey_ssh_name(l->key), l->path, l->linenum); if ((tmp = recallocarray(ctx->old_keys, ctx->nold, ctx->nold + 1, sizeof(*ctx->old_keys))) == NULL) fatal("%s: recallocarray failed nold = %zu", __func__, ctx->nold); ctx->old_keys = tmp; ctx->old_keys[ctx->nold++] = l->key; l->key = NULL; return 0; } static void update_known_hosts(struct hostkeys_update_ctx *ctx) { int r, was_raw = 0; int loglevel = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE; char *fp, *response; size_t i; for (i = 0; i < ctx->nkeys; i++) { if (ctx->keys_seen[i] != 2) continue; if ((fp = sshkey_fingerprint(ctx->keys[i], options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) fatal("%s: sshkey_fingerprint failed", __func__); do_log2(loglevel, "Learned new hostkey: %s %s", sshkey_type(ctx->keys[i]), fp); free(fp); } for (i = 0; i < ctx->nold; i++) { if ((fp = sshkey_fingerprint(ctx->old_keys[i], options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) fatal("%s: sshkey_fingerprint failed", __func__); do_log2(loglevel, "Deprecating obsolete hostkey: %s %s", sshkey_type(ctx->old_keys[i]), fp); free(fp); } if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) { if (get_saved_tio() != NULL) { leave_raw_mode(1); was_raw = 1; } response = NULL; for (i = 0; !quit_pending && i < 3; i++) { free(response); response = read_passphrase("Accept updated hostkeys? " "(yes/no): ", RP_ECHO); if (strcasecmp(response, "yes") == 0) break; else if (quit_pending || response == NULL || strcasecmp(response, "no") == 0) { options.update_hostkeys = 0; break; } else { do_log2(loglevel, "Please enter " "\"yes\" or \"no\""); } } if (quit_pending || i >= 3 || response == NULL) options.update_hostkeys = 0; free(response); if (was_raw) enter_raw_mode(1); } /* * Now that all the keys are verified, we can go ahead and replace * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't * cancel the operation). */ if (options.update_hostkeys != 0 && (r = hostfile_replace_entries(options.user_hostfiles[0], ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys, options.hash_known_hosts, 0, options.fingerprint_hash)) != 0) error("%s: hostfile_replace_entries failed: %s", __func__, ssh_err(r)); } static void client_global_hostkeys_private_confirm(struct ssh *ssh, int type, u_int32_t seq, void *_ctx) { struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx; size_t i, ndone; struct sshbuf *signdata; int r; const u_char *sig; size_t siglen; if (ctx->nnew == 0) fatal("%s: ctx->nnew == 0", __func__); /* sanity */ if (type != SSH2_MSG_REQUEST_SUCCESS) { error("Server failed to confirm ownership of " "private host keys"); hostkeys_update_ctx_free(ctx); return; } if ((signdata = sshbuf_new()) == NULL) fatal("%s: sshbuf_new failed", __func__); /* Don't want to accidentally accept an unbound signature */ if (ssh->kex->session_id_len == 0) fatal("%s: ssh->kex->session_id_len == 0", __func__); /* * Expect a signature for each of the ctx->nnew private keys we * haven't seen before. They will be in the same order as the * ctx->keys where the corresponding ctx->keys_seen[i] == 0. */ for (ndone = i = 0; i < ctx->nkeys; i++) { if (ctx->keys_seen[i]) continue; /* Prepare data to be signed: session ID, unique string, key */ sshbuf_reset(signdata); if ( (r = sshbuf_put_cstring(signdata, "hostkeys-prove-00@openssh.com")) != 0 || (r = sshbuf_put_string(signdata, ssh->kex->session_id, ssh->kex->session_id_len)) != 0 || (r = sshkey_puts(ctx->keys[i], signdata)) != 0) fatal("%s: failed to prepare signature: %s", __func__, ssh_err(r)); /* Extract and verify signature */ if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) { error("%s: couldn't parse message: %s", __func__, ssh_err(r)); goto out; } if ((r = sshkey_verify(ctx->keys[i], sig, siglen, sshbuf_ptr(signdata), sshbuf_len(signdata), 0)) != 0) { error("%s: server gave bad signature for %s key %zu", __func__, sshkey_type(ctx->keys[i]), i); goto out; } /* Key is good. Mark it as 'seen' */ ctx->keys_seen[i] = 2; ndone++; } if (ndone != ctx->nnew) fatal("%s: ndone != ctx->nnew (%zu / %zu)", __func__, ndone, ctx->nnew); /* Shouldn't happen */ ssh_packet_check_eom(ssh); /* Make the edits to known_hosts */ update_known_hosts(ctx); out: hostkeys_update_ctx_free(ctx); } /* * Returns non-zero if the key is accepted by HostkeyAlgorithms. * Made slightly less trivial by the multiple RSA signature algorithm names. */ static int key_accepted_by_hostkeyalgs(const struct sshkey *key) { const char *ktype = sshkey_ssh_name(key); const char *hostkeyalgs = options.hostkeyalgorithms != NULL ? options.hostkeyalgorithms : KEX_DEFAULT_PK_ALG; if (key == NULL || key->type == KEY_UNSPEC) return 0; if (key->type == KEY_RSA && (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) return 1; return match_pattern_list(ktype, hostkeyalgs, 0) == 1; } /* * Handle hostkeys-00@openssh.com global request to inform the client of all * the server's hostkeys. The keys are checked against the user's * HostkeyAlgorithms preference before they are accepted. */ static int client_input_hostkeys(void) { struct ssh *ssh = active_state; /* XXX */ const u_char *blob = NULL; size_t i, len = 0; struct sshbuf *buf = NULL; struct sshkey *key = NULL, **tmp; int r; char *fp; static int hostkeys_seen = 0; /* XXX use struct ssh */ extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */ struct hostkeys_update_ctx *ctx = NULL; if (hostkeys_seen) fatal("%s: server already sent hostkeys", __func__); if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK && options.batch_mode) return 1; /* won't ask in batchmode, so don't even try */ if (!options.update_hostkeys || options.num_user_hostfiles <= 0) return 1; ctx = xcalloc(1, sizeof(*ctx)); while (ssh_packet_remaining(ssh) > 0) { sshkey_free(key); key = NULL; if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) { error("%s: couldn't parse message: %s", __func__, ssh_err(r)); goto out; } if ((r = sshkey_from_blob(blob, len, &key)) != 0) { error("%s: parse key: %s", __func__, ssh_err(r)); goto out; } fp = sshkey_fingerprint(key, options.fingerprint_hash, SSH_FP_DEFAULT); debug3("%s: received %s key %s", __func__, sshkey_type(key), fp); free(fp); if (!key_accepted_by_hostkeyalgs(key)) { debug3("%s: %s key not permitted by HostkeyAlgorithms", __func__, sshkey_ssh_name(key)); continue; } /* Skip certs */ if (sshkey_is_cert(key)) { debug3("%s: %s key is a certificate; skipping", __func__, sshkey_ssh_name(key)); continue; } /* Ensure keys are unique */ for (i = 0; i < ctx->nkeys; i++) { if (sshkey_equal(key, ctx->keys[i])) { error("%s: received duplicated %s host key", __func__, sshkey_ssh_name(key)); goto out; } } /* Key is good, record it */ if ((tmp = recallocarray(ctx->keys, ctx->nkeys, ctx->nkeys + 1, sizeof(*ctx->keys))) == NULL) fatal("%s: recallocarray failed nkeys = %zu", __func__, ctx->nkeys); ctx->keys = tmp; ctx->keys[ctx->nkeys++] = key; key = NULL; } if (ctx->nkeys == 0) { debug("%s: server sent no hostkeys", __func__); goto out; } if ((ctx->keys_seen = calloc(ctx->nkeys, sizeof(*ctx->keys_seen))) == NULL) fatal("%s: calloc failed", __func__); get_hostfile_hostname_ipaddr(host, options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL, options.port, &ctx->host_str, options.check_host_ip ? &ctx->ip_str : NULL); /* Find which keys we already know about. */ if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find, ctx, ctx->host_str, ctx->ip_str, HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) { error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r)); goto out; } /* Figure out if we have any new keys to add */ ctx->nnew = 0; for (i = 0; i < ctx->nkeys; i++) { if (!ctx->keys_seen[i]) ctx->nnew++; } debug3("%s: %zu keys from server: %zu new, %zu retained. %zu to remove", __func__, ctx->nkeys, ctx->nnew, ctx->nkeys - ctx->nnew, ctx->nold); if (ctx->nnew == 0 && ctx->nold != 0) { /* We have some keys to remove. Just do it. */ update_known_hosts(ctx); } else if (ctx->nnew != 0) { /* * We have received hitherto-unseen keys from the server. * Ask the server to confirm ownership of the private halves. */ debug3("%s: asking server to prove ownership for %zu keys", __func__, ctx->nnew); if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || (r = sshpkt_put_cstring(ssh, "hostkeys-prove-00@openssh.com")) != 0 || (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */ fatal("%s: cannot prepare packet: %s", __func__, ssh_err(r)); if ((buf = sshbuf_new()) == NULL) fatal("%s: sshbuf_new", __func__); for (i = 0; i < ctx->nkeys; i++) { if (ctx->keys_seen[i]) continue; sshbuf_reset(buf); if ((r = sshkey_putb(ctx->keys[i], buf)) != 0) fatal("%s: sshkey_putb: %s", __func__, ssh_err(r)); if ((r = sshpkt_put_stringb(ssh, buf)) != 0) fatal("%s: sshpkt_put_string: %s", __func__, ssh_err(r)); } if ((r = sshpkt_send(ssh)) != 0) fatal("%s: sshpkt_send: %s", __func__, ssh_err(r)); client_register_global_confirm( client_global_hostkeys_private_confirm, ctx); ctx = NULL; /* will be freed in callback */ } /* Success */ out: hostkeys_update_ctx_free(ctx); sshkey_free(key); sshbuf_free(buf); /* * NB. Return success for all cases. The server doesn't need to know * what the client does with its hosts file. */ return 1; } static int client_input_global_request(int type, u_int32_t seq, struct ssh *ssh) { char *rtype; int want_reply; int success = 0; rtype = packet_get_cstring(NULL); want_reply = packet_get_char(); debug("client_input_global_request: rtype %s want_reply %d", rtype, want_reply); if (strcmp(rtype, "hostkeys-00@openssh.com") == 0) success = client_input_hostkeys(); if (want_reply) { packet_start(success ? SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); packet_send(); packet_write_wait(); } free(rtype); return 0; } void client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem, const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env) { int len; Channel *c = NULL; debug2("%s: id %d", __func__, id); if ((c = channel_lookup(ssh, id)) == NULL) fatal("%s: channel %d: unknown channel", __func__, id); packet_set_interactive(want_tty, options.ip_qos_interactive, options.ip_qos_bulk); if (want_tty) { struct winsize ws; /* Store window size in the packet. */ if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0) memset(&ws, 0, sizeof(ws)); channel_request_start(ssh, id, "pty-req", 1); client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY); packet_put_cstring(term != NULL ? term : ""); packet_put_int((u_int)ws.ws_col); packet_put_int((u_int)ws.ws_row); packet_put_int((u_int)ws.ws_xpixel); packet_put_int((u_int)ws.ws_ypixel); if (tiop == NULL) tiop = get_saved_tio(); tty_make_modes(-1, tiop); packet_send(); /* XXX wait for reply */ c->client_tty = 1; } /* Transfer any environment variables from client to server */ if (options.num_send_env != 0 && env != NULL) { int i, j, matched; char *name, *val; debug("Sending environment."); for (i = 0; env[i] != NULL; i++) { /* Split */ name = xstrdup(env[i]); if ((val = strchr(name, '=')) == NULL) { free(name); continue; } *val++ = '\0'; matched = 0; for (j = 0; j < options.num_send_env; j++) { if (match_pattern(name, options.send_env[j])) { matched = 1; break; } } if (!matched) { debug3("Ignored env %s", name); free(name); continue; } debug("Sending env %s = %s", name, val); channel_request_start(ssh, id, "env", 0); packet_put_cstring(name); packet_put_cstring(val); packet_send(); free(name); } } len = buffer_len(cmd); if (len > 0) { if (len > 900) len = 900; if (want_subsystem) { debug("Sending subsystem: %.*s", len, (u_char*)buffer_ptr(cmd)); channel_request_start(ssh, id, "subsystem", 1); client_expect_confirm(ssh, id, "subsystem", CONFIRM_CLOSE); } else { debug("Sending command: %.*s", len, (u_char*)buffer_ptr(cmd)); channel_request_start(ssh, id, "exec", 1); client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE); } packet_put_string(buffer_ptr(cmd), buffer_len(cmd)); packet_send(); } else { channel_request_start(ssh, id, "shell", 1); client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE); packet_send(); } } static void client_init_dispatch(void) { 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, &client_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, &client_input_channel_req); dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm); dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm); dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request); /* rekeying */ dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); /* global request reply messages */ dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply); dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply); } void client_stop_mux(void) { if (options.control_path != NULL && muxserver_sock != -1) unlink(options.control_path); /* * If we are in persist mode, or don't have a shell, signal that we * should close when all active channels are closed. */ if (options.control_persist || no_shell_flag) { session_closed = 1; setproctitle("[stopped mux]"); } } /* client specific fatal cleanup */ void cleanup_exit(int i) { leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE); leave_non_blocking(); if (options.control_path != NULL && muxserver_sock != -1) unlink(options.control_path); ssh_kill_proxy_command(); _exit(i); }