/* $OpenBSD: ssh.c,v 1.388 2013/10/17 00:46:49 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * Ssh client program. This program can be used to log into a remote machine. * The software supports strong authentication, encryption, and forwarding * of X11, TCP/IP, and authentication connections. * * 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 Niels Provos. All rights reserved. * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl. All rights reserved. * * Modified to work with SSL by Niels Provos * in Canada (German citizen). * * 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 #include #include #include #include #include #include #include "xmalloc.h" #include "ssh.h" #include "ssh1.h" #include "ssh2.h" #include "canohost.h" #include "compat.h" #include "cipher.h" #include "packet.h" #include "buffer.h" #include "channels.h" #include "key.h" #include "authfd.h" #include "authfile.h" #include "pathnames.h" #include "dispatch.h" #include "clientloop.h" #include "log.h" #include "readconf.h" #include "sshconnect.h" #include "misc.h" #include "kex.h" #include "mac.h" #include "sshpty.h" #include "match.h" #include "msg.h" #include "uidswap.h" #include "roaming.h" #include "version.h" #ifdef ENABLE_PKCS11 #include "ssh-pkcs11.h" #endif extern char *__progname; /* Flag indicating whether debug mode is on. May be set on the command line. */ int debug_flag = 0; /* Flag indicating whether a tty should be requested */ int tty_flag = 0; /* don't exec a shell */ int no_shell_flag = 0; /* * Flag indicating that nothing should be read from stdin. This can be set * on the command line. */ int stdin_null_flag = 0; /* * Flag indicating that the current process should be backgrounded and * a new slave launched in the foreground for ControlPersist. */ int need_controlpersist_detach = 0; /* Copies of flags for ControlPersist foreground slave */ int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty; /* * Flag indicating that ssh should fork after authentication. This is useful * so that the passphrase can be entered manually, and then ssh goes to the * background. */ int fork_after_authentication_flag = 0; /* forward stdio to remote host and port */ char *stdio_forward_host = NULL; int stdio_forward_port = 0; /* * General data structure for command line options and options configurable * in configuration files. See readconf.h. */ Options options; /* optional user configfile */ char *config = NULL; /* * 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. */ char *host; /* socket address the host resolves to */ struct sockaddr_storage hostaddr; /* Private host keys. */ Sensitive sensitive_data; /* Original real UID. */ uid_t original_real_uid; uid_t original_effective_uid; /* command to be executed */ Buffer command; /* Should we execute a command or invoke a subsystem? */ int subsystem_flag = 0; /* # of replies received for global requests */ static int remote_forward_confirms_received = 0; /* mux.c */ extern int muxserver_sock; extern u_int muxclient_command; /* Prints a help message to the user. This function never returns. */ static void usage(void) { fprintf(stderr, "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n" " [-D [bind_address:]port] [-E log_file] [-e escape_char]\n" " [-F configfile] [-I pkcs11] [-i identity_file]\n" " [-L [bind_address:]port:host:hostport] [-Q protocol_feature]\n" " [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n" " [-R [bind_address:]port:host:hostport] [-S ctl_path]\n" " [-W host:port] [-w local_tun[:remote_tun]]\n" " [user@]hostname [command]\n" ); exit(255); } static int ssh_session(void); static int ssh_session2(void); static void load_public_identity_files(void); static void main_sigchld_handler(int); /* from muxclient.c */ void muxclient(const char *); void muxserver_listen(void); /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */ static void tilde_expand_paths(char **paths, u_int num_paths) { u_int i; char *cp; for (i = 0; i < num_paths; i++) { cp = tilde_expand_filename(paths[i], original_real_uid); free(paths[i]); paths[i] = cp; } } static struct addrinfo * resolve_host(const char *name, u_int port, int logerr, char *cname, size_t clen) { char strport[NI_MAXSERV]; struct addrinfo hints, *res; int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1; snprintf(strport, sizeof strport, "%u", port); bzero(&hints, sizeof(hints)); hints.ai_family = options.address_family; hints.ai_socktype = SOCK_STREAM; if (cname != NULL) hints.ai_flags = AI_CANONNAME; if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) { if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA)) loglevel = SYSLOG_LEVEL_ERROR; do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s", __progname, name, ssh_gai_strerror(gaierr)); return NULL; } if (cname != NULL && res->ai_canonname != NULL) { if (strlcpy(cname, res->ai_canonname, clen) >= clen) { error("%s: host \"%s\" cname \"%s\" too long (max %lu)", __func__, name, res->ai_canonname, (u_long)clen); if (clen > 0) *cname = '\0'; } } return res; } /* * Check whether the cname is a permitted replacement for the hostname * and perform the replacement if it is. */ static int check_follow_cname(char **namep, const char *cname) { int i; struct allowed_cname *rule; if (*cname == '\0' || options.num_permitted_cnames == 0 || strcmp(*namep, cname) == 0) return 0; if (options.canonicalize_hostname == SSH_CANONICALISE_NO) return 0; /* * Don't attempt to canonicalize names that will be interpreted by * a proxy unless the user specifically requests so. */ if (options.proxy_command != NULL && options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS) return 0; debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname); for (i = 0; i < options.num_permitted_cnames; i++) { rule = options.permitted_cnames + i; if (match_pattern_list(*namep, rule->source_list, strlen(rule->source_list), 1) != 1 || match_pattern_list(cname, rule->target_list, strlen(rule->target_list), 1) != 1) continue; verbose("Canonicalized DNS aliased hostname " "\"%s\" => \"%s\"", *namep, cname); free(*namep); *namep = xstrdup(cname); return 1; } return 0; } /* * Attempt to resolve the supplied hostname after applying the user's * canonicalization rules. Returns the address list for the host or NULL * if no name was found after canonicalization. */ static struct addrinfo * resolve_canonicalize(char **hostp, u_int port) { int i, ndots; char *cp, *fullhost, cname_target[NI_MAXHOST]; struct addrinfo *addrs; if (options.canonicalize_hostname == SSH_CANONICALISE_NO) return NULL; /* * Don't attempt to canonicalize names that will be interpreted by * a proxy unless the user specifically requests so. */ if (options.proxy_command != NULL && options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS) return NULL; /* Don't apply canonicalization to sufficiently-qualified hostnames */ ndots = 0; for (cp = *hostp; *cp != '\0'; cp++) { if (*cp == '.') ndots++; } if (ndots > options.canonicalize_max_dots) { debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)", __func__, *hostp, options.canonicalize_max_dots); return NULL; } /* Attempt each supplied suffix */ for (i = 0; i < options.num_canonical_domains; i++) { *cname_target = '\0'; xasprintf(&fullhost, "%s.%s.", *hostp, options.canonical_domains[i]); if ((addrs = resolve_host(fullhost, options.port, 0, cname_target, sizeof(cname_target))) == NULL) { free(fullhost); continue; } /* Remove trailing '.' */ fullhost[strlen(fullhost) - 1] = '\0'; /* Follow CNAME if requested */ if (!check_follow_cname(&fullhost, cname_target)) { debug("Canonicalized hostname \"%s\" => \"%s\"", *hostp, fullhost); } free(*hostp); *hostp = fullhost; return addrs; } if (!options.canonicalize_fallback_local) fatal("%s: Could not resolve host \"%s\"", __progname, host); return NULL; } /* * Main program for the ssh client. */ int main(int ac, char **av) { int i, r, opt, exit_status, use_syslog; char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg, *logfile; char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV]; char cname[NI_MAXHOST]; struct stat st; struct passwd *pw; int timeout_ms; extern int optind, optreset; extern char *optarg; Forward fwd; struct addrinfo *addrs = NULL; /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ sanitise_stdfd(); /* * Discard other fds that are hanging around. These can cause problem * with backgrounded ssh processes started by ControlPersist. */ closefrom(STDERR_FILENO + 1); /* * Save the original real uid. It will be needed later (uid-swapping * may clobber the real uid). */ original_real_uid = getuid(); original_effective_uid = geteuid(); /* * Use uid-swapping to give up root privileges for the duration of * option processing. We will re-instantiate the rights when we are * ready to create the privileged port, and will permanently drop * them when the port has been created (actually, when the connection * has been made, as we may need to create the port several times). */ PRIV_END; /* If we are installed setuid root be careful to not drop core. */ if (original_real_uid != original_effective_uid) { struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = 0; if (setrlimit(RLIMIT_CORE, &rlim) < 0) fatal("setrlimit failed: %.100s", strerror(errno)); } /* Get user data. */ pw = getpwuid(original_real_uid); if (!pw) { logit("No user exists for uid %lu", (u_long)original_real_uid); exit(255); } /* Take a copy of the returned structure. */ pw = pwcopy(pw); /* * Set our umask to something reasonable, as some files are created * with the default umask. This will make them world-readable but * writable only by the owner, which is ok for all files for which we * don't set the modes explicitly. */ umask(022); /* * Initialize option structure to indicate that no values have been * set. */ initialize_options(&options); /* Parse command-line arguments. */ host = NULL; use_syslog = 0; logfile = NULL; argv0 = av[0]; again: while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx" "ACD:E:F:I:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) { switch (opt) { case '1': options.protocol = SSH_PROTO_1; break; case '2': options.protocol = SSH_PROTO_2; break; case '4': options.address_family = AF_INET; break; case '6': options.address_family = AF_INET6; break; case 'n': stdin_null_flag = 1; break; case 'f': fork_after_authentication_flag = 1; stdin_null_flag = 1; break; case 'x': options.forward_x11 = 0; break; case 'X': options.forward_x11 = 1; break; case 'y': use_syslog = 1; break; case 'E': logfile = xstrdup(optarg); break; case 'Y': options.forward_x11 = 1; options.forward_x11_trusted = 1; break; case 'g': options.gateway_ports = 1; break; case 'O': if (stdio_forward_host != NULL) fatal("Cannot specify multiplexing " "command with -W"); else if (muxclient_command != 0) fatal("Multiplexing command already specified"); if (strcmp(optarg, "check") == 0) muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK; else if (strcmp(optarg, "forward") == 0) muxclient_command = SSHMUX_COMMAND_FORWARD; else if (strcmp(optarg, "exit") == 0) muxclient_command = SSHMUX_COMMAND_TERMINATE; else if (strcmp(optarg, "stop") == 0) muxclient_command = SSHMUX_COMMAND_STOP; else if (strcmp(optarg, "cancel") == 0) muxclient_command = SSHMUX_COMMAND_CANCEL_FWD; else fatal("Invalid multiplex command."); break; case 'P': /* deprecated */ options.use_privileged_port = 0; break; case 'Q': /* deprecated */ cp = NULL; if (strcasecmp(optarg, "cipher") == 0) cp = cipher_alg_list(); else if (strcasecmp(optarg, "mac") == 0) cp = mac_alg_list(); else if (strcasecmp(optarg, "kex") == 0) cp = kex_alg_list(); else if (strcasecmp(optarg, "key") == 0) cp = key_alg_list(); if (cp == NULL) fatal("Unsupported query \"%s\"", optarg); printf("%s\n", cp); free(cp); exit(0); break; case 'a': options.forward_agent = 0; break; case 'A': options.forward_agent = 1; break; case 'k': options.gss_deleg_creds = 0; break; case 'K': options.gss_authentication = 1; options.gss_deleg_creds = 1; break; case 'i': if (stat(optarg, &st) < 0) { fprintf(stderr, "Warning: Identity file %s " "not accessible: %s.\n", optarg, strerror(errno)); break; } add_identity_file(&options, NULL, optarg, 1); break; case 'I': #ifdef ENABLE_PKCS11 options.pkcs11_provider = xstrdup(optarg); #else fprintf(stderr, "no support for PKCS#11.\n"); #endif break; case 't': if (options.request_tty == REQUEST_TTY_YES) options.request_tty = REQUEST_TTY_FORCE; else options.request_tty = REQUEST_TTY_YES; break; case 'v': if (debug_flag == 0) { debug_flag = 1; options.log_level = SYSLOG_LEVEL_DEBUG1; } else { if (options.log_level < SYSLOG_LEVEL_DEBUG3) options.log_level++; } break; case 'V': fprintf(stderr, "%s, %s\n", SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); if (opt == 'V') exit(0); break; case 'w': if (options.tun_open == -1) options.tun_open = SSH_TUNMODE_DEFAULT; options.tun_local = a2tun(optarg, &options.tun_remote); if (options.tun_local == SSH_TUNID_ERR) { fprintf(stderr, "Bad tun device '%s'\n", optarg); exit(255); } break; case 'W': if (stdio_forward_host != NULL) fatal("stdio forward already specified"); if (muxclient_command != 0) fatal("Cannot specify stdio forward with -O"); if (parse_forward(&fwd, optarg, 1, 0)) { stdio_forward_host = fwd.listen_host; stdio_forward_port = fwd.listen_port; free(fwd.connect_host); } else { fprintf(stderr, "Bad stdio forwarding specification '%s'\n", optarg); exit(255); } options.request_tty = REQUEST_TTY_NO; no_shell_flag = 1; options.clear_forwardings = 1; options.exit_on_forward_failure = 1; break; case 'q': options.log_level = SYSLOG_LEVEL_QUIET; break; case 'e': if (optarg[0] == '^' && optarg[2] == 0 && (u_char) optarg[1] >= 64 && (u_char) optarg[1] < 128) options.escape_char = (u_char) optarg[1] & 31; else if (strlen(optarg) == 1) options.escape_char = (u_char) optarg[0]; else if (strcmp(optarg, "none") == 0) options.escape_char = SSH_ESCAPECHAR_NONE; else { fprintf(stderr, "Bad escape character '%s'.\n", optarg); exit(255); } break; case 'c': if (ciphers_valid(optarg)) { /* SSH2 only */ options.ciphers = xstrdup(optarg); options.cipher = SSH_CIPHER_INVALID; } else { /* SSH1 only */ options.cipher = cipher_number(optarg); if (options.cipher == -1) { fprintf(stderr, "Unknown cipher type '%s'\n", optarg); exit(255); } if (options.cipher == SSH_CIPHER_3DES) options.ciphers = "3des-cbc"; else if (options.cipher == SSH_CIPHER_BLOWFISH) options.ciphers = "blowfish-cbc"; else options.ciphers = (char *)-1; } break; case 'm': if (mac_valid(optarg)) options.macs = xstrdup(optarg); else { fprintf(stderr, "Unknown mac type '%s'\n", optarg); exit(255); } break; case 'M': if (options.control_master == SSHCTL_MASTER_YES) options.control_master = SSHCTL_MASTER_ASK; else options.control_master = SSHCTL_MASTER_YES; break; case 'p': options.port = a2port(optarg); if (options.port <= 0) { fprintf(stderr, "Bad port '%s'\n", optarg); exit(255); } break; case 'l': options.user = optarg; break; case 'L': if (parse_forward(&fwd, optarg, 0, 0)) add_local_forward(&options, &fwd); else { fprintf(stderr, "Bad local forwarding specification '%s'\n", optarg); exit(255); } break; case 'R': if (parse_forward(&fwd, optarg, 0, 1)) { add_remote_forward(&options, &fwd); } else { fprintf(stderr, "Bad remote forwarding specification " "'%s'\n", optarg); exit(255); } break; case 'D': if (parse_forward(&fwd, optarg, 1, 0)) { add_local_forward(&options, &fwd); } else { fprintf(stderr, "Bad dynamic forwarding specification " "'%s'\n", optarg); exit(255); } break; case 'C': options.compression = 1; break; case 'N': no_shell_flag = 1; options.request_tty = REQUEST_TTY_NO; break; case 'T': options.request_tty = REQUEST_TTY_NO; break; case 'o': line = xstrdup(optarg); if (process_config_line(&options, pw, host ? host : "", line, "command-line", 0, NULL, SSHCONF_USERCONF) != 0) exit(255); free(line); break; case 's': subsystem_flag = 1; break; case 'S': if (options.control_path != NULL) free(options.control_path); options.control_path = xstrdup(optarg); break; case 'b': options.bind_address = optarg; break; case 'F': config = optarg; break; default: usage(); } } ac -= optind; av += optind; if (ac > 0 && !host) { if (strrchr(*av, '@')) { p = xstrdup(*av); cp = strrchr(p, '@'); if (cp == NULL || cp == p) usage(); options.user = p; *cp = '\0'; host = xstrdup(++cp); } else host = xstrdup(*av); if (ac > 1) { optind = optreset = 1; goto again; } ac--, av++; } /* Check that we got a host name. */ if (!host) usage(); lowercase(host); host_arg = xstrdup(host); OpenSSL_add_all_algorithms(); ERR_load_crypto_strings(); /* Initialize the command to execute on remote host. */ buffer_init(&command); /* * Save the command to execute on the remote host in a buffer. There * is no limit on the length of the command, except by the maximum * packet size. Also sets the tty flag if there is no command. */ if (!ac) { /* No command specified - execute shell on a tty. */ if (subsystem_flag) { fprintf(stderr, "You must specify a subsystem to invoke.\n"); usage(); } } else { /* A command has been specified. Store it into the buffer. */ for (i = 0; i < ac; i++) { if (i) buffer_append(&command, " ", 1); buffer_append(&command, av[i], strlen(av[i])); } } /* Cannot fork to background if no command. */ if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag) fatal("Cannot fork into background without a command " "to execute."); /* * Initialize "log" output. Since we are the client all output * goes to stderr unless otherwise specified by -y or -E. */ if (use_syslog && logfile != NULL) fatal("Can't specify both -y and -E"); if (logfile != NULL) { log_redirect_stderr_to(logfile); free(logfile); } log_init(argv0, options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, SYSLOG_FACILITY_USER, !use_syslog); if (debug_flag) logit("%s, %s", SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); /* * Read per-user configuration file. Ignore the system wide config * file if the user specifies a config file on the command line. */ if (config != NULL) { if (strcasecmp(config, "none") != 0 && !read_config_file(config, pw, host, &options, SSHCONF_USERCONF)) fatal("Can't open user config file %.100s: " "%.100s", config, strerror(errno)); } else { r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, _PATH_SSH_USER_CONFFILE); if (r > 0 && (size_t)r < sizeof(buf)) (void)read_config_file(buf, pw, host, &options, SSHCONF_CHECKPERM|SSHCONF_USERCONF); /* Read systemwide configuration file after user config. */ (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, host, &options, 0); } /* Fill configuration defaults. */ fill_default_options(&options); channel_set_af(options.address_family); /* Tidy and check options */ if (options.host_key_alias != NULL) lowercase(options.host_key_alias); if (options.proxy_command != NULL && strcmp(options.proxy_command, "-") == 0 && options.proxy_use_fdpass) fatal("ProxyCommand=- and ProxyUseFDPass are incompatible"); if (original_effective_uid != 0) options.use_privileged_port = 0; /* reinit */ log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog); if (options.request_tty == REQUEST_TTY_YES || options.request_tty == REQUEST_TTY_FORCE) tty_flag = 1; /* Allocate a tty by default if no command specified. */ if (buffer_len(&command) == 0) tty_flag = options.request_tty != REQUEST_TTY_NO; /* Force no tty */ if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0) tty_flag = 0; /* Do not allocate a tty if stdin is not a tty. */ if ((!isatty(fileno(stdin)) || stdin_null_flag) && options.request_tty != REQUEST_TTY_FORCE) { if (tty_flag) logit("Pseudo-terminal will not be allocated because " "stdin is not a terminal."); tty_flag = 0; } if (options.user == NULL) options.user = xstrdup(pw->pw_name); /* Get default port if port has not been set. */ if (options.port == 0) options.port = default_ssh_port(); /* preserve host name given on command line for %n expansion */ if (options.hostname != NULL) { cp = percent_expand(options.hostname, "h", host, (char *)NULL); free(host); host = cp; } /* If canonicalization requested then try to apply it */ if (options.canonicalize_hostname != SSH_CANONICALISE_NO) addrs = resolve_canonicalize(&host, options.port); /* * If canonicalization not requested, or if it failed then try to * resolve the bare hostname name using the system resolver's usual * search rules. */ if (addrs == NULL) { if ((addrs = resolve_host(host, options.port, 1, cname, sizeof(cname))) == NULL) cleanup_exit(255); /* resolve_host logs the error */ check_follow_cname(&host, cname); } if (gethostname(thishost, sizeof(thishost)) == -1) fatal("gethostname: %s", strerror(errno)); strlcpy(shorthost, thishost, sizeof(shorthost)); shorthost[strcspn(thishost, ".")] = '\0'; snprintf(portstr, sizeof(portstr), "%d", options.port); if (options.local_command != NULL) { debug3("expanding LocalCommand: %s", options.local_command); cp = options.local_command; options.local_command = percent_expand(cp, "d", pw->pw_dir, "h", host, "l", thishost, "n", host_arg, "r", options.user, "p", portstr, "u", pw->pw_name, "L", shorthost, (char *)NULL); debug3("expanded LocalCommand: %s", options.local_command); free(cp); } if (options.control_path != NULL) { cp = tilde_expand_filename(options.control_path, original_real_uid); free(options.control_path); options.control_path = percent_expand(cp, "h", host, "l", thishost, "n", host_arg, "r", options.user, "p", portstr, "u", pw->pw_name, "L", shorthost, (char *)NULL); free(cp); } if (muxclient_command != 0 && options.control_path == NULL) fatal("No ControlPath specified for \"-O\" command"); if (options.control_path != NULL) muxclient(options.control_path); timeout_ms = options.connection_timeout * 1000; /* Open a connection to the remote host. */ if (ssh_connect(host, addrs, &hostaddr, options.port, options.address_family, options.connection_attempts, &timeout_ms, options.tcp_keep_alive, options.use_privileged_port) != 0) exit(255); freeaddrinfo(addrs); packet_set_timeout(options.server_alive_interval, options.server_alive_count_max); if (timeout_ms > 0) debug3("timeout: %d ms remain after connect", timeout_ms); /* * If we successfully made the connection, load the host private key * in case we will need it later for combined rsa-rhosts * authentication. This must be done before releasing extra * privileges, because the file is only readable by root. * If we cannot access the private keys, load the public keys * instead and try to execute the ssh-keysign helper instead. */ sensitive_data.nkeys = 0; sensitive_data.keys = NULL; sensitive_data.external_keysign = 0; if (options.rhosts_rsa_authentication || options.hostbased_authentication) { sensitive_data.nkeys = 7; sensitive_data.keys = xcalloc(sensitive_data.nkeys, sizeof(Key)); PRIV_START; sensitive_data.keys[0] = key_load_private_type(KEY_RSA1, _PATH_HOST_KEY_FILE, "", NULL, NULL); sensitive_data.keys[1] = key_load_private_cert(KEY_DSA, _PATH_HOST_DSA_KEY_FILE, "", NULL); sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA, _PATH_HOST_ECDSA_KEY_FILE, "", NULL); sensitive_data.keys[3] = key_load_private_cert(KEY_RSA, _PATH_HOST_RSA_KEY_FILE, "", NULL); sensitive_data.keys[4] = key_load_private_type(KEY_DSA, _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL); sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA, _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL); sensitive_data.keys[6] = key_load_private_type(KEY_RSA, _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL); PRIV_END; if (options.hostbased_authentication == 1 && sensitive_data.keys[0] == NULL && sensitive_data.keys[4] == NULL && sensitive_data.keys[5] == NULL && sensitive_data.keys[6] == NULL) { sensitive_data.keys[1] = key_load_cert( _PATH_HOST_DSA_KEY_FILE); sensitive_data.keys[2] = key_load_cert( _PATH_HOST_ECDSA_KEY_FILE); sensitive_data.keys[3] = key_load_cert( _PATH_HOST_RSA_KEY_FILE); sensitive_data.keys[4] = key_load_public( _PATH_HOST_DSA_KEY_FILE, NULL); sensitive_data.keys[5] = key_load_public( _PATH_HOST_ECDSA_KEY_FILE, NULL); sensitive_data.keys[6] = key_load_public( _PATH_HOST_RSA_KEY_FILE, NULL); sensitive_data.external_keysign = 1; } } /* * Get rid of any extra privileges that we may have. We will no * longer need them. Also, extra privileges could make it very hard * to read identity files and other non-world-readable files from the * user's home directory if it happens to be on a NFS volume where * root is mapped to nobody. */ if (original_effective_uid == 0) { PRIV_START; permanently_set_uid(pw); } /* * Now that we are back to our own permissions, create ~/.ssh * directory if it doesn't already exist. */ if (config == NULL) { r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR); if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) if (mkdir(buf, 0700) < 0) error("Could not create directory '%.200s'.", buf); } /* load options.identity_files */ load_public_identity_files(); /* Expand ~ in known host file names. */ tilde_expand_paths(options.system_hostfiles, options.num_system_hostfiles); tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles); signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */ signal(SIGCHLD, main_sigchld_handler); /* Log into the remote system. Never returns if the login fails. */ ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, options.port, pw, timeout_ms); if (packet_connection_is_on_socket()) { verbose("Authenticated to %s ([%s]:%d).", host, get_remote_ipaddr(), get_remote_port()); } else { verbose("Authenticated to %s (via proxy).", host); } /* We no longer need the private host keys. Clear them now. */ if (sensitive_data.nkeys != 0) { for (i = 0; i < sensitive_data.nkeys; i++) { if (sensitive_data.keys[i] != NULL) { /* Destroys contents safely */ debug3("clear hostkey %d", i); key_free(sensitive_data.keys[i]); sensitive_data.keys[i] = NULL; } } free(sensitive_data.keys); } for (i = 0; i < options.num_identity_files; i++) { free(options.identity_files[i]); options.identity_files[i] = NULL; if (options.identity_keys[i]) { key_free(options.identity_keys[i]); options.identity_keys[i] = NULL; } } exit_status = compat20 ? ssh_session2() : ssh_session(); packet_close(); if (options.control_path != NULL && muxserver_sock != -1) unlink(options.control_path); /* Kill ProxyCommand if it is running. */ ssh_kill_proxy_command(); return exit_status; } static void control_persist_detach(void) { pid_t pid; int devnull; debug("%s: backgrounding master process", __func__); /* * master (current process) into the background, and make the * foreground process a client of the backgrounded master. */ switch ((pid = fork())) { case -1: fatal("%s: fork: %s", __func__, strerror(errno)); case 0: /* Child: master process continues mainloop */ break; default: /* Parent: set up mux slave to connect to backgrounded master */ debug2("%s: background process is %ld", __func__, (long)pid); stdin_null_flag = ostdin_null_flag; options.request_tty = orequest_tty; tty_flag = otty_flag; close(muxserver_sock); muxserver_sock = -1; options.control_master = SSHCTL_MASTER_NO; muxclient(options.control_path); /* muxclient() doesn't return on success. */ fatal("Failed to connect to new control master"); } if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) { error("%s: open(\"/dev/null\"): %s", __func__, strerror(errno)); } else { if (dup2(devnull, STDIN_FILENO) == -1 || dup2(devnull, STDOUT_FILENO) == -1) error("%s: dup2: %s", __func__, strerror(errno)); if (devnull > STDERR_FILENO) close(devnull); } daemon(1, 1); setproctitle("%s [mux]", options.control_path); } /* Do fork() after authentication. Used by "ssh -f" */ static void fork_postauth(void) { if (need_controlpersist_detach) control_persist_detach(); debug("forking to background"); fork_after_authentication_flag = 0; if (daemon(1, 1) < 0) fatal("daemon() failed: %.200s", strerror(errno)); } /* Callback for remote forward global requests */ static void ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt) { Forward *rfwd = (Forward *)ctxt; /* XXX verbose() on failure? */ debug("remote forward %s for: listen %d, connect %s:%d", type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure", rfwd->listen_port, rfwd->connect_host, rfwd->connect_port); if (rfwd->listen_port == 0) { if (type == SSH2_MSG_REQUEST_SUCCESS) { rfwd->allocated_port = packet_get_int(); logit("Allocated port %u for remote forward to %s:%d", rfwd->allocated_port, rfwd->connect_host, rfwd->connect_port); channel_update_permitted_opens(rfwd->handle, rfwd->allocated_port); } else { channel_update_permitted_opens(rfwd->handle, -1); } } if (type == SSH2_MSG_REQUEST_FAILURE) { if (options.exit_on_forward_failure) fatal("Error: remote port forwarding failed for " "listen port %d", rfwd->listen_port); else logit("Warning: remote port forwarding failed for " "listen port %d", rfwd->listen_port); } if (++remote_forward_confirms_received == options.num_remote_forwards) { debug("All remote forwarding requests processed"); if (fork_after_authentication_flag) fork_postauth(); } } static void client_cleanup_stdio_fwd(int id, void *arg) { debug("stdio forwarding: done"); cleanup_exit(0); } static void ssh_init_stdio_forwarding(void) { Channel *c; int in, out; if (stdio_forward_host == NULL) return; if (!compat20) fatal("stdio forwarding require Protocol 2"); debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port); if ((in = dup(STDIN_FILENO)) < 0 || (out = dup(STDOUT_FILENO)) < 0) fatal("channel_connect_stdio_fwd: dup() in/out failed"); if ((c = channel_connect_stdio_fwd(stdio_forward_host, stdio_forward_port, in, out)) == NULL) fatal("%s: channel_connect_stdio_fwd failed", __func__); channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0); } static void ssh_init_forwarding(void) { int success = 0; int i; /* Initiate local TCP/IP port forwardings. */ for (i = 0; i < options.num_local_forwards; i++) { debug("Local connections to %.200s:%d forwarded to remote " "address %.200s:%d", (options.local_forwards[i].listen_host == NULL) ? (options.gateway_ports ? "*" : "LOCALHOST") : options.local_forwards[i].listen_host, options.local_forwards[i].listen_port, options.local_forwards[i].connect_host, options.local_forwards[i].connect_port); success += channel_setup_local_fwd_listener( options.local_forwards[i].listen_host, options.local_forwards[i].listen_port, options.local_forwards[i].connect_host, options.local_forwards[i].connect_port, options.gateway_ports); } if (i > 0 && success != i && options.exit_on_forward_failure) fatal("Could not request local forwarding."); if (i > 0 && success == 0) error("Could not request local forwarding."); /* Initiate remote TCP/IP port forwardings. */ for (i = 0; i < options.num_remote_forwards; i++) { debug("Remote connections from %.200s:%d forwarded to " "local address %.200s:%d", (options.remote_forwards[i].listen_host == NULL) ? "LOCALHOST" : options.remote_forwards[i].listen_host, options.remote_forwards[i].listen_port, options.remote_forwards[i].connect_host, options.remote_forwards[i].connect_port); options.remote_forwards[i].handle = channel_request_remote_forwarding( options.remote_forwards[i].listen_host, options.remote_forwards[i].listen_port, options.remote_forwards[i].connect_host, options.remote_forwards[i].connect_port); if (options.remote_forwards[i].handle < 0) { if (options.exit_on_forward_failure) fatal("Could not request remote forwarding."); else logit("Warning: Could not request remote " "forwarding."); } else { client_register_global_confirm(ssh_confirm_remote_forward, &options.remote_forwards[i]); } } /* Initiate tunnel forwarding. */ if (options.tun_open != SSH_TUNMODE_NO) { if (client_request_tun_fwd(options.tun_open, options.tun_local, options.tun_remote) == -1) { if (options.exit_on_forward_failure) fatal("Could not request tunnel forwarding."); else error("Could not request tunnel forwarding."); } } } static void check_agent_present(void) { if (options.forward_agent) { /* Clear agent forwarding if we don't have an agent. */ if (!ssh_agent_present()) options.forward_agent = 0; } } static int ssh_session(void) { int type; int interactive = 0; int have_tty = 0; struct winsize ws; char *cp; const char *display; /* Enable compression if requested. */ if (options.compression) { debug("Requesting compression at level %d.", options.compression_level); if (options.compression_level < 1 || options.compression_level > 9) fatal("Compression level must be from 1 (fast) to " "9 (slow, best)."); /* Send the request. */ packet_start(SSH_CMSG_REQUEST_COMPRESSION); packet_put_int(options.compression_level); packet_send(); packet_write_wait(); type = packet_read(); if (type == SSH_SMSG_SUCCESS) packet_start_compression(options.compression_level); else if (type == SSH_SMSG_FAILURE) logit("Warning: Remote host refused compression."); else packet_disconnect("Protocol error waiting for " "compression response."); } /* Allocate a pseudo tty if appropriate. */ if (tty_flag) { debug("Requesting pty."); /* Start the packet. */ packet_start(SSH_CMSG_REQUEST_PTY); /* Store TERM in the packet. There is no limit on the length of the string. */ cp = getenv("TERM"); if (!cp) cp = ""; packet_put_cstring(cp); /* Store window size in the packet. */ if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0) memset(&ws, 0, sizeof(ws)); packet_put_int((u_int)ws.ws_row); packet_put_int((u_int)ws.ws_col); packet_put_int((u_int)ws.ws_xpixel); packet_put_int((u_int)ws.ws_ypixel); /* Store tty modes in the packet. */ tty_make_modes(fileno(stdin), NULL); /* Send the packet, and wait for it to leave. */ packet_send(); packet_write_wait(); /* Read response from the server. */ type = packet_read(); if (type == SSH_SMSG_SUCCESS) { interactive = 1; have_tty = 1; } else if (type == SSH_SMSG_FAILURE) logit("Warning: Remote host failed or refused to " "allocate a pseudo tty."); else packet_disconnect("Protocol error waiting for pty " "request response."); } /* Request X11 forwarding if enabled and DISPLAY is set. */ display = getenv("DISPLAY"); if (options.forward_x11 && display != NULL) { char *proto, *data; /* Get reasonable local authentication information. */ client_x11_get_proto(display, options.xauth_location, options.forward_x11_trusted, options.forward_x11_timeout, &proto, &data); /* Request forwarding with authentication spoofing. */ debug("Requesting X11 forwarding with authentication " "spoofing."); x11_request_forwarding_with_spoofing(0, display, proto, data, 0); /* Read response from the server. */ type = packet_read(); if (type == SSH_SMSG_SUCCESS) { interactive = 1; } else if (type == SSH_SMSG_FAILURE) { logit("Warning: Remote host denied X11 forwarding."); } else { packet_disconnect("Protocol error waiting for X11 " "forwarding"); } } /* Tell the packet module whether this is an interactive session. */ packet_set_interactive(interactive, options.ip_qos_interactive, options.ip_qos_bulk); /* Request authentication agent forwarding if appropriate. */ check_agent_present(); if (options.forward_agent) { debug("Requesting authentication agent forwarding."); auth_request_forwarding(); /* Read response from the server. */ type = packet_read(); packet_check_eom(); if (type != SSH_SMSG_SUCCESS) logit("Warning: Remote host denied authentication agent forwarding."); } /* Initiate port forwardings. */ ssh_init_stdio_forwarding(); ssh_init_forwarding(); /* Execute a local command */ if (options.local_command != NULL && options.permit_local_command) ssh_local_cmd(options.local_command); /* * If requested and we are not interested in replies to remote * forwarding requests, then let ssh continue in the background. */ if (fork_after_authentication_flag) { if (options.exit_on_forward_failure && options.num_remote_forwards > 0) { debug("deferring postauth fork until remote forward " "confirmation received"); } else fork_postauth(); } /* * If a command was specified on the command line, execute the * command now. Otherwise request the server to start a shell. */ if (buffer_len(&command) > 0) { int len = buffer_len(&command); if (len > 900) len = 900; debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command)); packet_start(SSH_CMSG_EXEC_CMD); packet_put_string(buffer_ptr(&command), buffer_len(&command)); packet_send(); packet_write_wait(); } else { debug("Requesting shell."); packet_start(SSH_CMSG_EXEC_SHELL); packet_send(); packet_write_wait(); } /* Enter the interactive session. */ return client_loop(have_tty, tty_flag ? options.escape_char : SSH_ESCAPECHAR_NONE, 0); } /* request pty/x11/agent/tcpfwd/shell for channel */ static void ssh_session2_setup(int id, int success, void *arg) { extern char **environ; const char *display; int interactive = tty_flag; if (!success) return; /* No need for error message, channels code sens one */ display = getenv("DISPLAY"); if (options.forward_x11 && display != NULL) { char *proto, *data; /* Get reasonable local authentication information. */ client_x11_get_proto(display, options.xauth_location, options.forward_x11_trusted, options.forward_x11_timeout, &proto, &data); /* Request forwarding with authentication spoofing. */ debug("Requesting X11 forwarding with authentication " "spoofing."); x11_request_forwarding_with_spoofing(id, display, proto, data, 1); client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN); /* XXX exit_on_forward_failure */ interactive = 1; } check_agent_present(); if (options.forward_agent) { debug("Requesting authentication agent forwarding."); channel_request_start(id, "auth-agent-req@openssh.com", 0); packet_send(); } /* Tell the packet module whether this is an interactive session. */ packet_set_interactive(interactive, options.ip_qos_interactive, options.ip_qos_bulk); client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"), NULL, fileno(stdin), &command, environ); } /* open new channel for a session */ static int ssh_session2_open(void) { Channel *c; int window, packetmax, in, out, err; if (stdin_null_flag) { in = open(_PATH_DEVNULL, O_RDONLY); } else { in = dup(STDIN_FILENO); } out = dup(STDOUT_FILENO); err = dup(STDERR_FILENO); if (in < 0 || out < 0 || err < 0) fatal("dup() in/out/err failed"); /* enable nonblocking unless tty */ if (!isatty(in)) set_nonblock(in); if (!isatty(out)) set_nonblock(out); if (!isatty(err)) set_nonblock(err); window = CHAN_SES_WINDOW_DEFAULT; packetmax = CHAN_SES_PACKET_DEFAULT; if (tty_flag) { window >>= 1; packetmax >>= 1; } c = channel_new( "session", SSH_CHANNEL_OPENING, in, out, err, window, packetmax, CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0); debug3("ssh_session2_open: channel_new: %d", c->self); channel_send_open(c->self); if (!no_shell_flag) channel_register_open_confirm(c->self, ssh_session2_setup, NULL); return c->self; } static int ssh_session2(void) { int id = -1; /* XXX should be pre-session */ if (!options.control_persist) ssh_init_stdio_forwarding(); ssh_init_forwarding(); /* Start listening for multiplex clients */ muxserver_listen(); /* * If we are in control persist mode and have a working mux listen * socket, then prepare to background ourselves and have a foreground * client attach as a control slave. * NB. we must save copies of the flags that we override for * the backgrounding, since we defer attachment of the slave until * after the connection is fully established (in particular, * async rfwd replies have been received for ExitOnForwardFailure). */ if (options.control_persist && muxserver_sock != -1) { ostdin_null_flag = stdin_null_flag; ono_shell_flag = no_shell_flag; orequest_tty = options.request_tty; otty_flag = tty_flag; stdin_null_flag = 1; no_shell_flag = 1; tty_flag = 0; if (!fork_after_authentication_flag) need_controlpersist_detach = 1; fork_after_authentication_flag = 1; } /* * ControlPersist mux listen socket setup failed, attempt the * stdio forward setup that we skipped earlier. */ if (options.control_persist && muxserver_sock == -1) ssh_init_stdio_forwarding(); if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN)) id = ssh_session2_open(); else { packet_set_interactive( options.control_master == SSHCTL_MASTER_NO, options.ip_qos_interactive, options.ip_qos_bulk); } /* If we don't expect to open a new session, then disallow it */ if (options.control_master == SSHCTL_MASTER_NO && (datafellows & SSH_NEW_OPENSSH)) { debug("Requesting no-more-sessions@openssh.com"); packet_start(SSH2_MSG_GLOBAL_REQUEST); packet_put_cstring("no-more-sessions@openssh.com"); packet_put_char(0); packet_send(); } /* Execute a local command */ if (options.local_command != NULL && options.permit_local_command) ssh_local_cmd(options.local_command); /* * If requested and we are not interested in replies to remote * forwarding requests, then let ssh continue in the background. */ if (fork_after_authentication_flag) { if (options.exit_on_forward_failure && options.num_remote_forwards > 0) { debug("deferring postauth fork until remote forward " "confirmation received"); } else fork_postauth(); } if (options.use_roaming) request_roaming(); return client_loop(tty_flag, tty_flag ? options.escape_char : SSH_ESCAPECHAR_NONE, id); } static void load_public_identity_files(void) { char *filename, *cp, thishost[NI_MAXHOST]; char *pwdir = NULL, *pwname = NULL; int i = 0; Key *public; struct passwd *pw; u_int n_ids; char *identity_files[SSH_MAX_IDENTITY_FILES]; Key *identity_keys[SSH_MAX_IDENTITY_FILES]; #ifdef ENABLE_PKCS11 Key **keys; int nkeys; #endif /* PKCS11 */ n_ids = 0; bzero(identity_files, sizeof(identity_files)); bzero(identity_keys, sizeof(identity_keys)); #ifdef ENABLE_PKCS11 if (options.pkcs11_provider != NULL && options.num_identity_files < SSH_MAX_IDENTITY_FILES && (pkcs11_init(!options.batch_mode) == 0) && (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL, &keys)) > 0) { for (i = 0; i < nkeys; i++) { if (n_ids >= SSH_MAX_IDENTITY_FILES) { key_free(keys[i]); continue; } identity_keys[n_ids] = keys[i]; identity_files[n_ids] = xstrdup(options.pkcs11_provider); /* XXX */ n_ids++; } free(keys); } #endif /* ENABLE_PKCS11 */ if ((pw = getpwuid(original_real_uid)) == NULL) fatal("load_public_identity_files: getpwuid failed"); pwname = xstrdup(pw->pw_name); pwdir = xstrdup(pw->pw_dir); if (gethostname(thishost, sizeof(thishost)) == -1) fatal("load_public_identity_files: gethostname: %s", strerror(errno)); for (i = 0; i < options.num_identity_files; i++) { if (n_ids >= SSH_MAX_IDENTITY_FILES || strcasecmp(options.identity_files[i], "none") == 0) { free(options.identity_files[i]); continue; } cp = tilde_expand_filename(options.identity_files[i], original_real_uid); filename = percent_expand(cp, "d", pwdir, "u", pwname, "l", thishost, "h", host, "r", options.user, (char *)NULL); free(cp); public = key_load_public(filename, NULL); debug("identity file %s type %d", filename, public ? public->type : -1); free(options.identity_files[i]); identity_files[n_ids] = filename; identity_keys[n_ids] = public; if (++n_ids >= SSH_MAX_IDENTITY_FILES) continue; /* Try to add the certificate variant too */ xasprintf(&cp, "%s-cert", filename); public = key_load_public(cp, NULL); debug("identity file %s type %d", cp, public ? public->type : -1); if (public == NULL) { free(cp); continue; } if (!key_is_cert(public)) { debug("%s: key %s type %s is not a certificate", __func__, cp, key_type(public)); key_free(public); free(cp); continue; } identity_keys[n_ids] = public; /* point to the original path, most likely the private key */ identity_files[n_ids] = xstrdup(filename); n_ids++; } options.num_identity_files = n_ids; memcpy(options.identity_files, identity_files, sizeof(identity_files)); memcpy(options.identity_keys, identity_keys, sizeof(identity_keys)); bzero(pwname, strlen(pwname)); free(pwname); bzero(pwdir, strlen(pwdir)); free(pwdir); } static void main_sigchld_handler(int sig) { int save_errno = errno; pid_t pid; int status; while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || (pid < 0 && errno == EINTR)) ; signal(sig, main_sigchld_handler); errno = save_errno; }