| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * Created: Fri Mar 17 17:09:28 1995 ylo |
| * This program is the ssh daemon. It listens for connections from clients, and |
| * performs authentication, executes use commands or shell, and forwards |
| * information to/from the application to the user client over an encrypted |
| * connection. This can also handle forwarding of X11, TCP/IP, and authentication |
| * agent connections. |
| */ |
| |
| #include "includes.h" |
| RCSID("$OpenBSD: sshd.c,v 1.80 2000/01/20 15:19:22 markus Exp $"); |
| |
| #include "xmalloc.h" |
| #include "rsa.h" |
| #include "ssh.h" |
| #include "pty.h" |
| #include "packet.h" |
| #include "buffer.h" |
| #include "cipher.h" |
| #include "mpaux.h" |
| #include "servconf.h" |
| #include "uidswap.h" |
| #include "compat.h" |
| |
| #ifdef LIBWRAP |
| #include <tcpd.h> |
| #include <syslog.h> |
| int allow_severity = LOG_INFO; |
| int deny_severity = LOG_WARNING; |
| #endif /* LIBWRAP */ |
| |
| #ifndef O_NOCTTY |
| #define O_NOCTTY 0 |
| #endif |
| |
| /* Local Xauthority file. */ |
| static char *xauthfile = NULL; |
| |
| /* Server configuration options. */ |
| ServerOptions options; |
| |
| /* Name of the server configuration file. */ |
| char *config_file_name = SERVER_CONFIG_FILE; |
| |
| /* |
| * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
| * Default value is AF_UNSPEC means both IPv4 and IPv6. |
| */ |
| #ifdef IPV4_DEFAULT |
| int IPv4or6 = AF_INET; |
| #else |
| int IPv4or6 = AF_UNSPEC; |
| #endif |
| |
| /* |
| * Debug mode flag. This can be set on the command line. If debug |
| * mode is enabled, extra debugging output will be sent to the system |
| * log, the daemon will not go to background, and will exit after processing |
| * the first connection. |
| */ |
| int debug_flag = 0; |
| |
| /* Flag indicating that the daemon is being started from inetd. */ |
| int inetd_flag = 0; |
| |
| /* debug goes to stderr unless inetd_flag is set */ |
| int log_stderr = 0; |
| |
| /* argv[0] without path. */ |
| char *av0; |
| |
| /* Saved arguments to main(). */ |
| char **saved_argv; |
| |
| /* |
| * The sockets that the server is listening; this is used in the SIGHUP |
| * signal handler. |
| */ |
| #define MAX_LISTEN_SOCKS 16 |
| int listen_socks[MAX_LISTEN_SOCKS]; |
| int num_listen_socks = 0; |
| |
| /* |
| * the client's version string, passed by sshd2 in compat mode. if != NULL, |
| * sshd will skip the version-number exchange |
| */ |
| char *client_version_string = NULL; |
| |
| /* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */ |
| int no_port_forwarding_flag = 0; |
| int no_agent_forwarding_flag = 0; |
| int no_x11_forwarding_flag = 0; |
| int no_pty_flag = 0; |
| |
| /* RSA authentication "command=" option. */ |
| char *forced_command = NULL; |
| |
| /* RSA authentication "environment=" options. */ |
| struct envstring *custom_environment = NULL; |
| |
| /* Session id for the current session. */ |
| unsigned char session_id[16]; |
| |
| /* |
| * Any really sensitive data in the application is contained in this |
| * structure. The idea is that this structure could be locked into memory so |
| * that the pages do not get written into swap. However, there are some |
| * problems. The private key contains BIGNUMs, and we do not (in principle) |
| * have access to the internals of them, and locking just the structure is |
| * not very useful. Currently, memory locking is not implemented. |
| */ |
| struct { |
| RSA *private_key; /* Private part of server key. */ |
| RSA *host_key; /* Private part of host key. */ |
| } sensitive_data; |
| |
| /* |
| * Flag indicating whether the current session key has been used. This flag |
| * is set whenever the key is used, and cleared when the key is regenerated. |
| */ |
| int key_used = 0; |
| |
| /* This is set to true when SIGHUP is received. */ |
| int received_sighup = 0; |
| |
| /* Public side of the server key. This value is regenerated regularly with |
| the private key. */ |
| RSA *public_key; |
| |
| /* Prototypes for various functions defined later in this file. */ |
| void do_ssh_kex(); |
| void do_authentication(); |
| void do_authloop(struct passwd * pw); |
| void do_fake_authloop(char *user); |
| void do_authenticated(struct passwd * pw); |
| void do_exec_pty(const char *command, int ptyfd, int ttyfd, |
| const char *ttyname, struct passwd * pw, const char *term, |
| const char *display, const char *auth_proto, |
| const char *auth_data); |
| void do_exec_no_pty(const char *command, struct passwd * pw, |
| const char *display, const char *auth_proto, |
| const char *auth_data); |
| void do_child(const char *command, struct passwd * pw, const char *term, |
| const char *display, const char *auth_proto, |
| const char *auth_data, const char *ttyname); |
| |
| /* |
| * Close all listening sockets |
| */ |
| void |
| close_listen_socks(void) |
| { |
| int i; |
| for (i = 0; i < num_listen_socks; i++) |
| close(listen_socks[i]); |
| num_listen_socks = -1; |
| } |
| |
| /* |
| * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; |
| * the effect is to reread the configuration file (and to regenerate |
| * the server key). |
| */ |
| void |
| sighup_handler(int sig) |
| { |
| received_sighup = 1; |
| signal(SIGHUP, sighup_handler); |
| } |
| |
| /* |
| * Called from the main program after receiving SIGHUP. |
| * Restarts the server. |
| */ |
| void |
| sighup_restart() |
| { |
| log("Received SIGHUP; restarting."); |
| close_listen_socks(); |
| execv(saved_argv[0], saved_argv); |
| log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); |
| exit(1); |
| } |
| |
| /* |
| * Generic signal handler for terminating signals in the master daemon. |
| * These close the listen socket; not closing it seems to cause "Address |
| * already in use" problems on some machines, which is inconvenient. |
| */ |
| void |
| sigterm_handler(int sig) |
| { |
| log("Received signal %d; terminating.", sig); |
| close_listen_socks(); |
| exit(255); |
| } |
| |
| /* |
| * SIGCHLD handler. This is called whenever a child dies. This will then |
| * reap any zombies left by exited c. |
| */ |
| void |
| main_sigchld_handler(int sig) |
| { |
| int save_errno = errno; |
| int status; |
| |
| while (waitpid(-1, &status, WNOHANG) > 0) |
| ; |
| |
| signal(SIGCHLD, main_sigchld_handler); |
| errno = save_errno; |
| } |
| |
| /* |
| * Signal handler for the alarm after the login grace period has expired. |
| */ |
| void |
| grace_alarm_handler(int sig) |
| { |
| /* Close the connection. */ |
| packet_close(); |
| |
| /* Log error and exit. */ |
| fatal("Timeout before authentication for %s.", get_remote_ipaddr()); |
| } |
| |
| /* |
| * convert ssh auth msg type into description |
| */ |
| char * |
| get_authname(int type) |
| { |
| switch (type) { |
| case SSH_CMSG_AUTH_PASSWORD: |
| return "password"; |
| case SSH_CMSG_AUTH_RSA: |
| return "rsa"; |
| case SSH_CMSG_AUTH_RHOSTS_RSA: |
| return "rhosts-rsa"; |
| case SSH_CMSG_AUTH_RHOSTS: |
| return "rhosts"; |
| #ifdef KRB4 |
| case SSH_CMSG_AUTH_KERBEROS: |
| return "kerberos"; |
| #endif |
| #ifdef SKEY |
| case SSH_CMSG_AUTH_TIS_RESPONSE: |
| return "s/key"; |
| #endif |
| } |
| fatal("get_authname: unknown auth %d: internal error", type); |
| return NULL; |
| } |
| |
| /* |
| * Signal handler for the key regeneration alarm. Note that this |
| * alarm only occurs in the daemon waiting for connections, and it does not |
| * do anything with the private key or random state before forking. |
| * Thus there should be no concurrency control/asynchronous execution |
| * problems. |
| */ |
| void |
| key_regeneration_alarm(int sig) |
| { |
| int save_errno = errno; |
| |
| /* Check if we should generate a new key. */ |
| if (key_used) { |
| /* This should really be done in the background. */ |
| log("Generating new %d bit RSA key.", options.server_key_bits); |
| |
| if (sensitive_data.private_key != NULL) |
| RSA_free(sensitive_data.private_key); |
| sensitive_data.private_key = RSA_new(); |
| |
| if (public_key != NULL) |
| RSA_free(public_key); |
| public_key = RSA_new(); |
| |
| rsa_generate_key(sensitive_data.private_key, public_key, |
| options.server_key_bits); |
| arc4random_stir(); |
| key_used = 0; |
| log("RSA key generation complete."); |
| } |
| /* Reschedule the alarm. */ |
| signal(SIGALRM, key_regeneration_alarm); |
| alarm(options.key_regeneration_time); |
| errno = save_errno; |
| } |
| |
| /* |
| * Main program for the daemon. |
| */ |
| int |
| main(int ac, char **av) |
| { |
| extern char *optarg; |
| extern int optind; |
| int opt, sock_in = 0, sock_out = 0, newsock, i, fdsetsz, pid, on = 1; |
| socklen_t fromlen; |
| int remote_major, remote_minor; |
| int silentrsa = 0; |
| fd_set *fdset; |
| struct sockaddr_storage from; |
| char buf[100]; /* Must not be larger than remote_version. */ |
| char remote_version[100]; /* Must be at least as big as buf. */ |
| const char *remote_ip; |
| int remote_port; |
| char *comment; |
| FILE *f; |
| struct linger linger; |
| struct addrinfo *ai; |
| char ntop[NI_MAXHOST], strport[NI_MAXSERV]; |
| int listen_sock, maxfd; |
| |
| /* Save argv[0]. */ |
| saved_argv = av; |
| if (strchr(av[0], '/')) |
| av0 = strrchr(av[0], '/') + 1; |
| else |
| av0 = av[0]; |
| |
| /* Initialize configuration options to their default values. */ |
| initialize_server_options(&options); |
| |
| /* Parse command-line arguments. */ |
| while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ46")) != EOF) { |
| switch (opt) { |
| case '4': |
| IPv4or6 = AF_INET; |
| break; |
| case '6': |
| IPv4or6 = AF_INET6; |
| break; |
| case 'f': |
| config_file_name = optarg; |
| break; |
| case 'd': |
| debug_flag = 1; |
| options.log_level = SYSLOG_LEVEL_DEBUG; |
| break; |
| case 'i': |
| inetd_flag = 1; |
| break; |
| case 'Q': |
| silentrsa = 1; |
| break; |
| case 'q': |
| options.log_level = SYSLOG_LEVEL_QUIET; |
| break; |
| case 'b': |
| options.server_key_bits = atoi(optarg); |
| break; |
| case 'p': |
| options.ports_from_cmdline = 1; |
| if (options.num_ports >= MAX_PORTS) |
| fatal("too many ports.\n"); |
| options.ports[options.num_ports++] = atoi(optarg); |
| break; |
| case 'g': |
| options.login_grace_time = atoi(optarg); |
| break; |
| case 'k': |
| options.key_regeneration_time = atoi(optarg); |
| break; |
| case 'h': |
| options.host_key_file = optarg; |
| break; |
| case 'V': |
| client_version_string = optarg; |
| /* only makes sense with inetd_flag, i.e. no listen() */ |
| inetd_flag = 1; |
| break; |
| case '?': |
| default: |
| fprintf(stderr, "sshd version %s\n", SSH_VERSION); |
| #ifdef RSAREF |
| fprintf(stderr, "Compiled with RSAref.\n"); |
| #endif |
| fprintf(stderr, "Usage: %s [options]\n", av0); |
| fprintf(stderr, "Options:\n"); |
| fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
| fprintf(stderr, " -d Debugging mode\n"); |
| fprintf(stderr, " -i Started from inetd\n"); |
| fprintf(stderr, " -q Quiet (no logging)\n"); |
| fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); |
| fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); |
| fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); |
| fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); |
| fprintf(stderr, " -h file File from which to read host key (default: %s)\n", |
| HOST_KEY_FILE); |
| fprintf(stderr, " -4 Use IPv4 only\n"); |
| fprintf(stderr, " -6 Use IPv6 only\n"); |
| exit(1); |
| } |
| } |
| |
| /* |
| * Force logging to stderr until we have loaded the private host |
| * key (unless started from inetd) |
| */ |
| log_init(av0, |
| options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, |
| options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, |
| !inetd_flag); |
| |
| /* check if RSA support exists */ |
| if (rsa_alive() == 0) { |
| if (silentrsa == 0) |
| printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); |
| log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); |
| exit(1); |
| } |
| /* Read server configuration options from the configuration file. */ |
| read_server_config(&options, config_file_name); |
| |
| /* Fill in default values for those options not explicitly set. */ |
| fill_default_server_options(&options); |
| |
| /* Check certain values for sanity. */ |
| if (options.server_key_bits < 512 || |
| options.server_key_bits > 32768) { |
| fprintf(stderr, "Bad server key size.\n"); |
| exit(1); |
| } |
| /* Check that there are no remaining arguments. */ |
| if (optind < ac) { |
| fprintf(stderr, "Extra argument %s.\n", av[optind]); |
| exit(1); |
| } |
| |
| debug("sshd version %.100s", SSH_VERSION); |
| |
| sensitive_data.host_key = RSA_new(); |
| errno = 0; |
| /* Load the host key. It must have empty passphrase. */ |
| if (!load_private_key(options.host_key_file, "", |
| sensitive_data.host_key, &comment)) { |
| error("Could not load host key: %.200s: %.100s", |
| options.host_key_file, strerror(errno)); |
| exit(1); |
| } |
| xfree(comment); |
| |
| /* Initialize the log (it is reinitialized below in case we |
| forked). */ |
| if (debug_flag && !inetd_flag) |
| log_stderr = 1; |
| log_init(av0, options.log_level, options.log_facility, log_stderr); |
| |
| /* If not in debugging mode, and not started from inetd, |
| disconnect from the controlling terminal, and fork. The |
| original process exits. */ |
| if (!debug_flag && !inetd_flag) { |
| #ifdef TIOCNOTTY |
| int fd; |
| #endif /* TIOCNOTTY */ |
| if (daemon(0, 0) < 0) |
| fatal("daemon() failed: %.200s", strerror(errno)); |
| |
| /* Disconnect from the controlling tty. */ |
| #ifdef TIOCNOTTY |
| fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
| if (fd >= 0) { |
| (void) ioctl(fd, TIOCNOTTY, NULL); |
| close(fd); |
| } |
| #endif /* TIOCNOTTY */ |
| } |
| /* Reinitialize the log (because of the fork above). */ |
| log_init(av0, options.log_level, options.log_facility, log_stderr); |
| |
| /* Check that server and host key lengths differ sufficiently. |
| This is necessary to make double encryption work with rsaref. |
| Oh, I hate software patents. I dont know if this can go? Niels */ |
| if (options.server_key_bits > |
| BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && |
| options.server_key_bits < |
| BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { |
| options.server_key_bits = |
| BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; |
| debug("Forcing server key to %d bits to make it differ from host key.", |
| options.server_key_bits); |
| } |
| /* Do not display messages to stdout in RSA code. */ |
| rsa_set_verbose(0); |
| |
| /* Initialize the random number generator. */ |
| arc4random_stir(); |
| |
| /* Chdir to the root directory so that the current disk can be |
| unmounted if desired. */ |
| chdir("/"); |
| |
| /* Close connection cleanly after attack. */ |
| cipher_attack_detected = packet_disconnect; |
| |
| /* Start listening for a socket, unless started from inetd. */ |
| if (inetd_flag) { |
| int s1, s2; |
| s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
| s2 = dup(s1); |
| sock_in = dup(0); |
| sock_out = dup(1); |
| /* We intentionally do not close the descriptors 0, 1, and 2 |
| as our code for setting the descriptors won\'t work |
| if ttyfd happens to be one of those. */ |
| debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
| |
| public_key = RSA_new(); |
| sensitive_data.private_key = RSA_new(); |
| |
| log("Generating %d bit RSA key.", options.server_key_bits); |
| rsa_generate_key(sensitive_data.private_key, public_key, |
| options.server_key_bits); |
| arc4random_stir(); |
| log("RSA key generation complete."); |
| } else { |
| for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
| if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) |
| continue; |
| if (num_listen_socks >= MAX_LISTEN_SOCKS) |
| fatal("Too many listen sockets. " |
| "Enlarge MAX_LISTEN_SOCKS"); |
| if (getnameinfo(ai->ai_addr, ai->ai_addrlen, |
| ntop, sizeof(ntop), strport, sizeof(strport), |
| NI_NUMERICHOST|NI_NUMERICSERV) != 0) { |
| error("getnameinfo failed"); |
| continue; |
| } |
| /* Create socket for listening. */ |
| listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); |
| if (listen_sock < 0) { |
| /* kernel may not support ipv6 */ |
| verbose("socket: %.100s", strerror(errno)); |
| continue; |
| } |
| if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { |
| error("listen_sock O_NONBLOCK: %s", strerror(errno)); |
| close(listen_sock); |
| continue; |
| } |
| /* |
| * Set socket options. We try to make the port |
| * reusable and have it close as fast as possible |
| * without waiting in unnecessary wait states on |
| * close. |
| */ |
| setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
| (void *) &on, sizeof(on)); |
| linger.l_onoff = 1; |
| linger.l_linger = 5; |
| setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, |
| (void *) &linger, sizeof(linger)); |
| |
| debug("Bind to port %s on %s.", strport, ntop); |
| |
| /* Bind the socket to the desired port. */ |
| if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
| error("Bind to port %s on %s failed: %.200s.", |
| strport, ntop, strerror(errno)); |
| close(listen_sock); |
| continue; |
| } |
| listen_socks[num_listen_socks] = listen_sock; |
| num_listen_socks++; |
| |
| /* Start listening on the port. */ |
| log("Server listening on %s port %s.", ntop, strport); |
| if (listen(listen_sock, 5) < 0) |
| fatal("listen: %.100s", strerror(errno)); |
| |
| } |
| freeaddrinfo(options.listen_addrs); |
| |
| if (!num_listen_socks) |
| fatal("Cannot bind any address."); |
| |
| if (!debug_flag) { |
| /* |
| * Record our pid in /etc/sshd_pid to make it easier |
| * to kill the correct sshd. We don\'t want to do |
| * this before the bind above because the bind will |
| * fail if there already is a daemon, and this will |
| * overwrite any old pid in the file. |
| */ |
| f = fopen(SSH_DAEMON_PID_FILE, "w"); |
| if (f) { |
| fprintf(f, "%u\n", (unsigned int) getpid()); |
| fclose(f); |
| } |
| } |
| |
| public_key = RSA_new(); |
| sensitive_data.private_key = RSA_new(); |
| |
| log("Generating %d bit RSA key.", options.server_key_bits); |
| rsa_generate_key(sensitive_data.private_key, public_key, |
| options.server_key_bits); |
| arc4random_stir(); |
| log("RSA key generation complete."); |
| |
| /* Schedule server key regeneration alarm. */ |
| signal(SIGALRM, key_regeneration_alarm); |
| alarm(options.key_regeneration_time); |
| |
| /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ |
| signal(SIGHUP, sighup_handler); |
| signal(SIGTERM, sigterm_handler); |
| signal(SIGQUIT, sigterm_handler); |
| |
| /* Arrange SIGCHLD to be caught. */ |
| signal(SIGCHLD, main_sigchld_handler); |
| |
| /* setup fd set for listen */ |
| maxfd = 0; |
| for (i = 0; i < num_listen_socks; i++) |
| if (listen_socks[i] > maxfd) |
| maxfd = listen_socks[i]; |
| fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask); |
| fdset = (fd_set *)xmalloc(fdsetsz); |
| |
| /* |
| * Stay listening for connections until the system crashes or |
| * the daemon is killed with a signal. |
| */ |
| for (;;) { |
| if (received_sighup) |
| sighup_restart(); |
| /* Wait in select until there is a connection. */ |
| memset(fdset, 0, fdsetsz); |
| for (i = 0; i < num_listen_socks; i++) |
| FD_SET(listen_socks[i], fdset); |
| if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) { |
| if (errno != EINTR) |
| error("select: %.100s", strerror(errno)); |
| continue; |
| } |
| for (i = 0; i < num_listen_socks; i++) { |
| if (!FD_ISSET(listen_socks[i], fdset)) |
| continue; |
| fromlen = sizeof(from); |
| newsock = accept(listen_socks[i], (struct sockaddr *)&from, |
| &fromlen); |
| if (newsock < 0) { |
| if (errno != EINTR && errno != EWOULDBLOCK) |
| error("accept: %.100s", strerror(errno)); |
| continue; |
| } |
| if (fcntl(newsock, F_SETFL, 0) < 0) { |
| error("newsock del O_NONBLOCK: %s", strerror(errno)); |
| continue; |
| } |
| /* |
| * Got connection. Fork a child to handle it, unless |
| * we are in debugging mode. |
| */ |
| if (debug_flag) { |
| /* |
| * In debugging mode. Close the listening |
| * socket, and start processing the |
| * connection without forking. |
| */ |
| debug("Server will not fork when running in debugging mode."); |
| close_listen_socks(); |
| sock_in = newsock; |
| sock_out = newsock; |
| pid = getpid(); |
| break; |
| } else { |
| /* |
| * Normal production daemon. Fork, and have |
| * the child process the connection. The |
| * parent continues listening. |
| */ |
| if ((pid = fork()) == 0) { |
| /* |
| * Child. Close the listening socket, and start using the |
| * accepted socket. Reinitialize logging (since our pid has |
| * changed). We break out of the loop to handle the connection. |
| */ |
| close_listen_socks(); |
| sock_in = newsock; |
| sock_out = newsock; |
| log_init(av0, options.log_level, options.log_facility, log_stderr); |
| break; |
| } |
| } |
| |
| /* Parent. Stay in the loop. */ |
| if (pid < 0) |
| error("fork: %.100s", strerror(errno)); |
| else |
| debug("Forked child %d.", pid); |
| |
| /* Mark that the key has been used (it was "given" to the child). */ |
| key_used = 1; |
| |
| arc4random_stir(); |
| |
| /* Close the new socket (the child is now taking care of it). */ |
| close(newsock); |
| } /* for (i = 0; i < num_listen_socks; i++) */ |
| /* child process check (or debug mode) */ |
| if (num_listen_socks < 0) |
| break; |
| } |
| } |
| |
| /* This is the child processing a new connection. */ |
| |
| /* |
| * Disable the key regeneration alarm. We will not regenerate the |
| * key since we are no longer in a position to give it to anyone. We |
| * will not restart on SIGHUP since it no longer makes sense. |
| */ |
| alarm(0); |
| signal(SIGALRM, SIG_DFL); |
| signal(SIGHUP, SIG_DFL); |
| signal(SIGTERM, SIG_DFL); |
| signal(SIGQUIT, SIG_DFL); |
| signal(SIGCHLD, SIG_DFL); |
| |
| /* |
| * Set socket options for the connection. We want the socket to |
| * close as fast as possible without waiting for anything. If the |
| * connection is not a socket, these will do nothing. |
| */ |
| /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ |
| linger.l_onoff = 1; |
| linger.l_linger = 5; |
| setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); |
| |
| /* |
| * Register our connection. This turns encryption off because we do |
| * not have a key. |
| */ |
| packet_set_connection(sock_in, sock_out); |
| |
| remote_port = get_remote_port(); |
| remote_ip = get_remote_ipaddr(); |
| |
| /* Check whether logins are denied from this host. */ |
| #ifdef LIBWRAP |
| /* XXX LIBWRAP noes not know about IPv6 */ |
| { |
| struct request_info req; |
| |
| request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
| fromhost(&req); |
| |
| if (!hosts_access(&req)) { |
| close(sock_in); |
| close(sock_out); |
| refuse(&req); |
| } |
| /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
| } |
| #endif /* LIBWRAP */ |
| /* Log the connection. */ |
| verbose("Connection from %.500s port %d", remote_ip, remote_port); |
| |
| /* |
| * We don\'t want to listen forever unless the other side |
| * successfully authenticates itself. So we set up an alarm which is |
| * cleared after successful authentication. A limit of zero |
| * indicates no limit. Note that we don\'t set the alarm in debugging |
| * mode; it is just annoying to have the server exit just when you |
| * are about to discover the bug. |
| */ |
| signal(SIGALRM, grace_alarm_handler); |
| if (!debug_flag) |
| alarm(options.login_grace_time); |
| |
| if (client_version_string != NULL) { |
| /* we are exec'ed by sshd2, so skip exchange of protocol version */ |
| strlcpy(buf, client_version_string, sizeof(buf)); |
| } else { |
| /* Send our protocol version identification. */ |
| snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", |
| PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION); |
| if (atomicio(write, sock_out, buf, strlen(buf)) != strlen(buf)) { |
| log("Could not write ident string to %s.", remote_ip); |
| fatal_cleanup(); |
| } |
| |
| /* Read other side\'s version identification. */ |
| for (i = 0; i < sizeof(buf) - 1; i++) { |
| if (read(sock_in, &buf[i], 1) != 1) { |
| log("Did not receive ident string from %s.", remote_ip); |
| fatal_cleanup(); |
| } |
| if (buf[i] == '\r') { |
| buf[i] = '\n'; |
| buf[i + 1] = 0; |
| break; |
| } |
| if (buf[i] == '\n') { |
| /* buf[i] == '\n' */ |
| buf[i + 1] = 0; |
| break; |
| } |
| } |
| buf[sizeof(buf) - 1] = 0; |
| } |
| |
| /* |
| * Check that the versions match. In future this might accept |
| * several versions and set appropriate flags to handle them. |
| */ |
| if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, |
| remote_version) != 3) { |
| char *s = "Protocol mismatch.\n"; |
| |
| (void) atomicio(write, sock_out, s, strlen(s)); |
| close(sock_in); |
| close(sock_out); |
| log("Bad protocol version identification '%.100s' from %s", |
| buf, remote_ip); |
| fatal_cleanup(); |
| } |
| debug("Client protocol version %d.%d; client software version %.100s", |
| remote_major, remote_minor, remote_version); |
| if (remote_major != PROTOCOL_MAJOR) { |
| char *s = "Protocol major versions differ.\n"; |
| |
| (void) atomicio(write, sock_out, s, strlen(s)); |
| close(sock_in); |
| close(sock_out); |
| log("Protocol major versions differ for %s: %d vs. %d", |
| remote_ip, PROTOCOL_MAJOR, remote_major); |
| fatal_cleanup(); |
| } |
| /* Check that the client has sufficiently high software version. */ |
| if (remote_major == 1 && remote_minor < 3) |
| packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version."); |
| |
| if (remote_major == 1 && remote_minor == 3) { |
| /* note that this disables agent-forwarding */ |
| enable_compat13(); |
| } |
| /* |
| * Check that the connection comes from a privileged port. Rhosts- |
| * and Rhosts-RSA-Authentication only make sense from priviledged |
| * programs. Of course, if the intruder has root access on his local |
| * machine, he can connect from any port. So do not use these |
| * authentication methods from machines that you do not trust. |
| */ |
| if (remote_port >= IPPORT_RESERVED || |
| remote_port < IPPORT_RESERVED / 2) { |
| options.rhosts_authentication = 0; |
| options.rhosts_rsa_authentication = 0; |
| } |
| #ifdef KRB4 |
| if (!packet_connection_is_ipv4() && |
| options.kerberos_authentication) { |
| debug("Kerberos Authentication disabled, only available for IPv4."); |
| options.kerberos_authentication = 0; |
| } |
| #endif /* KRB4 */ |
| |
| packet_set_nonblocking(); |
| |
| /* perform the key exchange */ |
| do_ssh_kex(); |
| |
| /* authenticate user and start session */ |
| do_authentication(); |
| |
| #ifdef KRB4 |
| /* Cleanup user's ticket cache file. */ |
| if (options.kerberos_ticket_cleanup) |
| (void) dest_tkt(); |
| #endif /* KRB4 */ |
| |
| /* Cleanup user's local Xauthority file. */ |
| if (xauthfile) |
| unlink(xauthfile); |
| |
| /* The connection has been terminated. */ |
| verbose("Closing connection to %.100s", remote_ip); |
| |
| #ifdef USE_PAM |
| finish_pam(); |
| #endif /* USE_PAM */ |
| |
| packet_close(); |
| exit(0); |
| } |
| |
| /* |
| * SSH1 key exchange |
| */ |
| void |
| do_ssh_kex() |
| { |
| int i, len; |
| int plen, slen; |
| BIGNUM *session_key_int; |
| unsigned char session_key[SSH_SESSION_KEY_LENGTH]; |
| unsigned char cookie[8]; |
| unsigned int cipher_type, auth_mask, protocol_flags; |
| u_int32_t rand = 0; |
| |
| /* |
| * Generate check bytes that the client must send back in the user |
| * packet in order for it to be accepted; this is used to defy ip |
| * spoofing attacks. Note that this only works against somebody |
| * doing IP spoofing from a remote machine; any machine on the local |
| * network can still see outgoing packets and catch the random |
| * cookie. This only affects rhosts authentication, and this is one |
| * of the reasons why it is inherently insecure. |
| */ |
| for (i = 0; i < 8; i++) { |
| if (i % 4 == 0) |
| rand = arc4random(); |
| cookie[i] = rand & 0xff; |
| rand >>= 8; |
| } |
| |
| /* |
| * Send our public key. We include in the packet 64 bits of random |
| * data that must be matched in the reply in order to prevent IP |
| * spoofing. |
| */ |
| packet_start(SSH_SMSG_PUBLIC_KEY); |
| for (i = 0; i < 8; i++) |
| packet_put_char(cookie[i]); |
| |
| /* Store our public server RSA key. */ |
| packet_put_int(BN_num_bits(public_key->n)); |
| packet_put_bignum(public_key->e); |
| packet_put_bignum(public_key->n); |
| |
| /* Store our public host RSA key. */ |
| packet_put_int(BN_num_bits(sensitive_data.host_key->n)); |
| packet_put_bignum(sensitive_data.host_key->e); |
| packet_put_bignum(sensitive_data.host_key->n); |
| |
| /* Put protocol flags. */ |
| packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); |
| |
| /* Declare which ciphers we support. */ |
| packet_put_int(cipher_mask()); |
| |
| /* Declare supported authentication types. */ |
| auth_mask = 0; |
| if (options.rhosts_authentication) |
| auth_mask |= 1 << SSH_AUTH_RHOSTS; |
| if (options.rhosts_rsa_authentication) |
| auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; |
| if (options.rsa_authentication) |
| auth_mask |= 1 << SSH_AUTH_RSA; |
| #ifdef KRB4 |
| if (options.kerberos_authentication) |
| auth_mask |= 1 << SSH_AUTH_KERBEROS; |
| #endif |
| #ifdef AFS |
| if (options.kerberos_tgt_passing) |
| auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; |
| if (options.afs_token_passing) |
| auth_mask |= 1 << SSH_PASS_AFS_TOKEN; |
| #endif |
| #ifdef SKEY |
| if (options.skey_authentication == 1) |
| auth_mask |= 1 << SSH_AUTH_TIS; |
| #endif |
| if (options.password_authentication) |
| auth_mask |= 1 << SSH_AUTH_PASSWORD; |
| packet_put_int(auth_mask); |
| |
| /* Send the packet and wait for it to be sent. */ |
| packet_send(); |
| packet_write_wait(); |
| |
| debug("Sent %d bit public key and %d bit host key.", |
| BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); |
| |
| /* Read clients reply (cipher type and session key). */ |
| packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); |
| |
| /* Get cipher type and check whether we accept this. */ |
| cipher_type = packet_get_char(); |
| |
| if (!(cipher_mask() & (1 << cipher_type))) |
| packet_disconnect("Warning: client selects unsupported cipher."); |
| |
| /* Get check bytes from the packet. These must match those we |
| sent earlier with the public key packet. */ |
| for (i = 0; i < 8; i++) |
| if (cookie[i] != packet_get_char()) |
| packet_disconnect("IP Spoofing check bytes do not match."); |
| |
| debug("Encryption type: %.200s", cipher_name(cipher_type)); |
| |
| /* Get the encrypted integer. */ |
| session_key_int = BN_new(); |
| packet_get_bignum(session_key_int, &slen); |
| |
| protocol_flags = packet_get_int(); |
| packet_set_protocol_flags(protocol_flags); |
| |
| packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); |
| |
| /* |
| * Decrypt it using our private server key and private host key (key |
| * with larger modulus first). |
| */ |
| if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) { |
| /* Private key has bigger modulus. */ |
| if (BN_num_bits(sensitive_data.private_key->n) < |
| BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { |
| fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", |
| get_remote_ipaddr(), |
| BN_num_bits(sensitive_data.private_key->n), |
| BN_num_bits(sensitive_data.host_key->n), |
| SSH_KEY_BITS_RESERVED); |
| } |
| rsa_private_decrypt(session_key_int, session_key_int, |
| sensitive_data.private_key); |
| rsa_private_decrypt(session_key_int, session_key_int, |
| sensitive_data.host_key); |
| } else { |
| /* Host key has bigger modulus (or they are equal). */ |
| if (BN_num_bits(sensitive_data.host_key->n) < |
| BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { |
| fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", |
| get_remote_ipaddr(), |
| BN_num_bits(sensitive_data.host_key->n), |
| BN_num_bits(sensitive_data.private_key->n), |
| SSH_KEY_BITS_RESERVED); |
| } |
| rsa_private_decrypt(session_key_int, session_key_int, |
| sensitive_data.host_key); |
| rsa_private_decrypt(session_key_int, session_key_int, |
| sensitive_data.private_key); |
| } |
| |
| compute_session_id(session_id, cookie, |
| sensitive_data.host_key->n, |
| sensitive_data.private_key->n); |
| |
| /* Destroy the private and public keys. They will no longer be needed. */ |
| RSA_free(public_key); |
| RSA_free(sensitive_data.private_key); |
| RSA_free(sensitive_data.host_key); |
| |
| /* |
| * Extract session key from the decrypted integer. The key is in the |
| * least significant 256 bits of the integer; the first byte of the |
| * key is in the highest bits. |
| */ |
| BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
| len = BN_num_bytes(session_key_int); |
| if (len < 0 || len > sizeof(session_key)) |
| fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", |
| get_remote_ipaddr(), |
| len, sizeof(session_key)); |
| memset(session_key, 0, sizeof(session_key)); |
| BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); |
| |
| /* Destroy the decrypted integer. It is no longer needed. */ |
| BN_clear_free(session_key_int); |
| |
| /* Xor the first 16 bytes of the session key with the session id. */ |
| for (i = 0; i < 16; i++) |
| session_key[i] ^= session_id[i]; |
| |
| /* Set the session key. From this on all communications will be encrypted. */ |
| packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); |
| |
| /* Destroy our copy of the session key. It is no longer needed. */ |
| memset(session_key, 0, sizeof(session_key)); |
| |
| debug("Received session key; encryption turned on."); |
| |
| /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| } |
| |
| |
| /* |
| * Check if the user is allowed to log in via ssh. If user is listed in |
| * DenyUsers or user's primary group is listed in DenyGroups, false will |
| * be returned. If AllowUsers isn't empty and user isn't listed there, or |
| * if AllowGroups isn't empty and user isn't listed there, false will be |
| * returned. Otherwise true is returned. |
| * XXX This function should also check if user has a valid shell |
| */ |
| static int |
| allowed_user(struct passwd * pw) |
| { |
| struct group *grp; |
| int i; |
| #ifdef WITH_AIXAUTHENTICATE |
| char *loginmsg; |
| #endif /* WITH_AIXAUTHENTICATE */ |
| |
| /* Shouldn't be called if pw is NULL, but better safe than sorry... */ |
| if (!pw) |
| return 0; |
| |
| /* XXX Should check for valid login shell */ |
| |
| /* Return false if user is listed in DenyUsers */ |
| if (options.num_deny_users > 0) { |
| if (!pw->pw_name) |
| return 0; |
| for (i = 0; i < options.num_deny_users; i++) |
| if (match_pattern(pw->pw_name, options.deny_users[i])) |
| return 0; |
| } |
| /* Return false if AllowUsers isn't empty and user isn't listed there */ |
| if (options.num_allow_users > 0) { |
| if (!pw->pw_name) |
| return 0; |
| for (i = 0; i < options.num_allow_users; i++) |
| if (match_pattern(pw->pw_name, options.allow_users[i])) |
| break; |
| /* i < options.num_allow_users iff we break for loop */ |
| if (i >= options.num_allow_users) |
| return 0; |
| } |
| /* Get the primary group name if we need it. Return false if it fails */ |
| if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| grp = getgrgid(pw->pw_gid); |
| if (!grp) |
| return 0; |
| |
| /* Return false if user's group is listed in DenyGroups */ |
| if (options.num_deny_groups > 0) { |
| if (!grp->gr_name) |
| return 0; |
| for (i = 0; i < options.num_deny_groups; i++) |
| if (match_pattern(grp->gr_name, options.deny_groups[i])) |
| return 0; |
| } |
| /* |
| * Return false if AllowGroups isn't empty and user's group |
| * isn't listed there |
| */ |
| if (options.num_allow_groups > 0) { |
| if (!grp->gr_name) |
| return 0; |
| for (i = 0; i < options.num_allow_groups; i++) |
| if (match_pattern(grp->gr_name, options.allow_groups[i])) |
| break; |
| /* i < options.num_allow_groups iff we break for |
| loop */ |
| if (i >= options.num_allow_groups) |
| return 0; |
| } |
| } |
| |
| #ifdef WITH_AIXAUTHENTICATE |
| if (loginrestrictions(pw->pw_name,S_LOGIN,NULL,&loginmsg) != 0) |
| return 0; |
| #endif /* WITH_AIXAUTHENTICATE */ |
| |
| /* We found no reason not to let this user try to log on... */ |
| return 1; |
| } |
| |
| /* |
| * Performs authentication of an incoming connection. Session key has already |
| * been exchanged and encryption is enabled. |
| */ |
| void |
| do_authentication() |
| { |
| struct passwd *pw, pwcopy; |
| int plen, ulen; |
| char *user; |
| |
| /* Get the name of the user that we wish to log in as. */ |
| packet_read_expect(&plen, SSH_CMSG_USER); |
| |
| /* Get the user name. */ |
| user = packet_get_string(&ulen); |
| packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER); |
| |
| setproctitle("%s", user); |
| |
| #ifdef WITH_AIXAUTHENTICATE |
| char *loginmsg; |
| #endif /* WITH_AIXAUTHENTICATE */ |
| |
| #ifdef AFS |
| /* If machine has AFS, set process authentication group. */ |
| if (k_hasafs()) { |
| k_setpag(); |
| k_unlog(); |
| } |
| #endif /* AFS */ |
| |
| /* Verify that the user is a valid user. */ |
| pw = getpwnam(user); |
| if (!pw || !allowed_user(pw)) |
| do_fake_authloop(user); |
| |
| /* Take a copy of the returned structure. */ |
| memset(&pwcopy, 0, sizeof(pwcopy)); |
| pwcopy.pw_name = xstrdup(pw->pw_name); |
| pwcopy.pw_passwd = xstrdup(pw->pw_passwd); |
| pwcopy.pw_uid = pw->pw_uid; |
| pwcopy.pw_gid = pw->pw_gid; |
| pwcopy.pw_dir = xstrdup(pw->pw_dir); |
| pwcopy.pw_shell = xstrdup(pw->pw_shell); |
| pw = &pwcopy; |
| |
| #ifdef USE_PAM |
| start_pam(pw); |
| #endif |
| |
| /* |
| * If we are not running as root, the user must have the same uid as |
| * the server. |
| */ |
| if (getuid() != 0 && pw->pw_uid != getuid()) |
| packet_disconnect("Cannot change user when server not running as root."); |
| |
| debug("Attempting authentication for %.100s.", user); |
| |
| /* If the user has no password, accept authentication immediately. */ |
| if (options.password_authentication && |
| #ifdef KRB4 |
| (!options.kerberos_authentication || options.kerberos_or_local_passwd) && |
| #endif /* KRB4 */ |
| #ifdef USE_PAM |
| auth_pam_password(pw, "")) { |
| #else /* USE_PAM */ |
| auth_password(pw, "")) { |
| #endif /* USE_PAM */ |
| /* Authentication with empty password succeeded. */ |
| log("Login for user %s from %.100s, accepted without authentication.", |
| pw->pw_name, get_remote_ipaddr()); |
| } else { |
| /* Loop until the user has been authenticated or the |
| connection is closed, do_authloop() returns only if |
| authentication is successfull */ |
| do_authloop(pw); |
| } |
| |
| /* Check if the user is logging in as root and root logins are disallowed. */ |
| if (pw->pw_uid == 0 && !options.permit_root_login) { |
| if (forced_command) |
| log("Root login accepted for forced command."); |
| else |
| packet_disconnect("ROOT LOGIN REFUSED FROM %.200s", |
| get_canonical_hostname()); |
| } |
| /* The user has been authenticated and accepted. */ |
| #ifdef WITH_AIXAUTHENTICATE |
| loginsuccess(user,get_canonical_hostname(),"ssh",&loginmsg); |
| #endif /* WITH_AIXAUTHENTICATE */ |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| |
| /* Perform session preparation. */ |
| do_authenticated(pw); |
| } |
| |
| #define AUTH_FAIL_MAX 6 |
| #define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2) |
| #define AUTH_FAIL_MSG "Too many authentication failures for %.100s" |
| |
| /* |
| * read packets and try to authenticate local user *pw. |
| * return if authentication is successfull |
| */ |
| void |
| do_authloop(struct passwd * pw) |
| { |
| int attempt = 0; |
| unsigned int bits; |
| BIGNUM *client_host_key_e, *client_host_key_n; |
| BIGNUM *n; |
| char *client_user = NULL, *password = NULL; |
| char user[1024]; |
| int plen, dlen, nlen, ulen, elen; |
| int type = 0; |
| void (*authlog) (const char *fmt,...) = verbose; |
| |
| /* Indicate that authentication is needed. */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| |
| for (attempt = 1;; attempt++) { |
| int authenticated = 0; |
| strlcpy(user, "", sizeof user); |
| |
| /* Get a packet from the client. */ |
| type = packet_read(&plen); |
| |
| /* Process the packet. */ |
| switch (type) { |
| #ifdef AFS |
| case SSH_CMSG_HAVE_KERBEROS_TGT: |
| if (!options.kerberos_tgt_passing) { |
| /* packet_get_all(); */ |
| verbose("Kerberos tgt passing disabled."); |
| break; |
| } else { |
| /* Accept Kerberos tgt. */ |
| char *tgt = packet_get_string(&dlen); |
| packet_integrity_check(plen, 4 + dlen, type); |
| if (!auth_kerberos_tgt(pw, tgt)) |
| verbose("Kerberos tgt REFUSED for %s", pw->pw_name); |
| xfree(tgt); |
| } |
| continue; |
| |
| case SSH_CMSG_HAVE_AFS_TOKEN: |
| if (!options.afs_token_passing || !k_hasafs()) { |
| /* packet_get_all(); */ |
| verbose("AFS token passing disabled."); |
| break; |
| } else { |
| /* Accept AFS token. */ |
| char *token_string = packet_get_string(&dlen); |
| packet_integrity_check(plen, 4 + dlen, type); |
| if (!auth_afs_token(pw, token_string)) |
| verbose("AFS token REFUSED for %s", pw->pw_name); |
| xfree(token_string); |
| } |
| continue; |
| #endif /* AFS */ |
| #ifdef KRB4 |
| case SSH_CMSG_AUTH_KERBEROS: |
| if (!options.kerberos_authentication) { |
| /* packet_get_all(); */ |
| verbose("Kerberos authentication disabled."); |
| break; |
| } else { |
| /* Try Kerberos v4 authentication. */ |
| KTEXT_ST auth; |
| char *tkt_user = NULL; |
| char *kdata = packet_get_string((unsigned int *) &auth.length); |
| packet_integrity_check(plen, 4 + auth.length, type); |
| |
| if (auth.length < MAX_KTXT_LEN) |
| memcpy(auth.dat, kdata, auth.length); |
| xfree(kdata); |
| |
| authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user); |
| |
| if (authenticated) { |
| snprintf(user, sizeof user, " tktuser %s", tkt_user); |
| xfree(tkt_user); |
| } |
| } |
| break; |
| #endif /* KRB4 */ |
| |
| case SSH_CMSG_AUTH_RHOSTS: |
| if (!options.rhosts_authentication) { |
| verbose("Rhosts authentication disabled."); |
| break; |
| } |
| /* |
| * Get client user name. Note that we just have to |
| * trust the client; this is one reason why rhosts |
| * authentication is insecure. (Another is |
| * IP-spoofing on a local network.) |
| */ |
| client_user = packet_get_string(&ulen); |
| packet_integrity_check(plen, 4 + ulen, type); |
| |
| /* Try to authenticate using /etc/hosts.equiv and |
| .rhosts. */ |
| authenticated = auth_rhosts(pw, client_user); |
| |
| snprintf(user, sizeof user, " ruser %s", client_user); |
| break; |
| |
| case SSH_CMSG_AUTH_RHOSTS_RSA: |
| if (!options.rhosts_rsa_authentication) { |
| verbose("Rhosts with RSA authentication disabled."); |
| break; |
| } |
| /* |
| * Get client user name. Note that we just have to |
| * trust the client; root on the client machine can |
| * claim to be any user. |
| */ |
| client_user = packet_get_string(&ulen); |
| |
| /* Get the client host key. */ |
| client_host_key_e = BN_new(); |
| client_host_key_n = BN_new(); |
| bits = packet_get_int(); |
| packet_get_bignum(client_host_key_e, &elen); |
| packet_get_bignum(client_host_key_n, &nlen); |
| |
| if (bits != BN_num_bits(client_host_key_n)) |
| error("Warning: keysize mismatch for client_host_key: " |
| "actual %d, announced %d", BN_num_bits(client_host_key_n), bits); |
| packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type); |
| |
| authenticated = auth_rhosts_rsa(pw, client_user, |
| client_host_key_e, client_host_key_n); |
| BN_clear_free(client_host_key_e); |
| BN_clear_free(client_host_key_n); |
| |
| snprintf(user, sizeof user, " ruser %s", client_user); |
| break; |
| |
| case SSH_CMSG_AUTH_RSA: |
| if (!options.rsa_authentication) { |
| verbose("RSA authentication disabled."); |
| break; |
| } |
| /* RSA authentication requested. */ |
| n = BN_new(); |
| packet_get_bignum(n, &nlen); |
| packet_integrity_check(plen, nlen, type); |
| authenticated = auth_rsa(pw, n); |
| BN_clear_free(n); |
| break; |
| |
| case SSH_CMSG_AUTH_PASSWORD: |
| if (!options.password_authentication) { |
| verbose("Password authentication disabled."); |
| break; |
| } |
| /* |
| * Read user password. It is in plain text, but was |
| * transmitted over the encrypted channel so it is |
| * not visible to an outside observer. |
| */ |
| password = packet_get_string(&dlen); |
| packet_integrity_check(plen, 4 + dlen, type); |
| |
| #ifdef USE_PAM |
| /* Do PAM auth with password */ |
| authenticated = auth_pam_password(pw, password); |
| #else /* USE_PAM */ |
| /* Try authentication with the password. */ |
| authenticated = auth_password(pw, password); |
| #endif /* USE_PAM */ |
| memset(password, 0, strlen(password)); |
| xfree(password); |
| break; |
| |
| #ifdef SKEY |
| case SSH_CMSG_AUTH_TIS: |
| debug("rcvd SSH_CMSG_AUTH_TIS"); |
| if (options.skey_authentication == 1) { |
| char *skeyinfo = skey_keyinfo(pw->pw_name); |
| if (skeyinfo == NULL) { |
| debug("generating fake skeyinfo for %.100s.", pw->pw_name); |
| skeyinfo = skey_fake_keyinfo(pw->pw_name); |
| } |
| if (skeyinfo != NULL) { |
| /* we send our s/key- in tis-challenge messages */ |
| debug("sending challenge '%s'", skeyinfo); |
| packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
| packet_put_string(skeyinfo, strlen(skeyinfo)); |
| packet_send(); |
| packet_write_wait(); |
| continue; |
| } |
| } |
| break; |
| case SSH_CMSG_AUTH_TIS_RESPONSE: |
| debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE"); |
| if (options.skey_authentication == 1) { |
| char *response = packet_get_string(&dlen); |
| debug("skey response == '%s'", response); |
| packet_integrity_check(plen, 4 + dlen, type); |
| authenticated = (skey_haskey(pw->pw_name) == 0 && |
| skey_passcheck(pw->pw_name, response) != -1); |
| xfree(response); |
| } |
| break; |
| #else |
| case SSH_CMSG_AUTH_TIS: |
| /* TIS Authentication is unsupported */ |
| log("TIS authentication unsupported."); |
| break; |
| #endif |
| |
| default: |
| /* |
| * Any unknown messages will be ignored (and failure |
| * returned) during authentication. |
| */ |
| log("Unknown message during authentication: type %d", type); |
| break; |
| } |
| |
| /* Raise logging level */ |
| if (authenticated || |
| attempt == AUTH_FAIL_LOG || |
| type == SSH_CMSG_AUTH_PASSWORD) |
| authlog = log; |
| |
| authlog("%s %s for %.200s from %.200s port %d%s", |
| authenticated ? "Accepted" : "Failed", |
| get_authname(type), |
| pw->pw_uid == 0 ? "ROOT" : pw->pw_name, |
| get_remote_ipaddr(), |
| get_remote_port(), |
| user); |
| |
| if (authenticated) { |
| #ifdef USE_PAM |
| if (!do_pam_account(pw->pw_name, client_user)) { |
| if (client_user != NULL) |
| xfree(client_user); |
| |
| do_fake_authloop(pw->pw_name); |
| } |
| #endif /* USE_PAM */ |
| return; |
| } |
| |
| if (client_user != NULL) |
| xfree(client_user); |
| |
| if (attempt > AUTH_FAIL_MAX) |
| packet_disconnect(AUTH_FAIL_MSG, pw->pw_name); |
| |
| /* Send a message indicating that the authentication attempt failed. */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| } |
| } |
| |
| /* |
| * The user does not exist or access is denied, |
| * but fake indication that authentication is needed. |
| */ |
| void |
| do_fake_authloop(char *user) |
| { |
| int attempt = 0; |
| |
| log("Faking authloop for illegal user %.200s from %.200s port %d", |
| user, |
| get_remote_ipaddr(), |
| get_remote_port()); |
| |
| /* Indicate that authentication is needed. */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| |
| /* |
| * Keep reading packets, and always respond with a failure. This is |
| * to avoid disclosing whether such a user really exists. |
| */ |
| for (attempt = 1;; attempt++) { |
| /* Read a packet. This will not return if the client disconnects. */ |
| int plen; |
| #ifndef SKEY |
| (void)packet_read(&plen); |
| #else /* SKEY */ |
| int type = packet_read(&plen); |
| int dlen; |
| char *password, *skeyinfo; |
| /* Try to send a fake s/key challenge. */ |
| if (options.skey_authentication == 1 && |
| (skeyinfo = skey_fake_keyinfo(user)) != NULL) { |
| if (type == SSH_CMSG_AUTH_TIS) { |
| packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE); |
| packet_put_string(skeyinfo, strlen(skeyinfo)); |
| packet_send(); |
| packet_write_wait(); |
| continue; |
| } else if (type == SSH_CMSG_AUTH_PASSWORD && |
| options.password_authentication && |
| (password = packet_get_string(&dlen)) != NULL && |
| dlen == 5 && |
| strncasecmp(password, "s/key", 5) == 0 ) { |
| packet_send_debug(skeyinfo); |
| } |
| } |
| #endif |
| if (attempt > AUTH_FAIL_MAX) |
| packet_disconnect(AUTH_FAIL_MSG, user); |
| |
| /* |
| * Send failure. This should be indistinguishable from a |
| * failed authentication. |
| */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| #ifdef WITH_AIXAUTHENTICATE |
| if (strncmp(get_authname(type),"password", |
| strlen(get_authname(type))) == 0) |
| loginfailed(pw->pw_name,get_canonical_hostname(),"ssh"); |
| #endif /* WITH_AIXAUTHENTICATE */ |
| } |
| /* NOTREACHED */ |
| abort(); |
| } |
| |
| |
| /* |
| * Remove local Xauthority file. |
| */ |
| static void |
| xauthfile_cleanup_proc(void *ignore) |
| { |
| debug("xauthfile_cleanup_proc called"); |
| |
| if (xauthfile != NULL) { |
| unlink(xauthfile); |
| xfree(xauthfile); |
| xauthfile = NULL; |
| } |
| } |
| |
| /* |
| * Prepares for an interactive session. This is called after the user has |
| * been successfully authenticated. During this message exchange, pseudo |
| * terminals are allocated, X11, TCP/IP, and authentication agent forwardings |
| * are requested, etc. |
| */ |
| void |
| do_authenticated(struct passwd * pw) |
| { |
| int type; |
| int compression_level = 0, enable_compression_after_reply = 0; |
| int have_pty = 0, ptyfd = -1, ttyfd = -1, xauthfd = -1; |
| int row, col, xpixel, ypixel, screen; |
| char ttyname[64]; |
| char *command, *term = NULL, *display = NULL, *proto = NULL, |
| *data = NULL; |
| struct group *grp; |
| gid_t tty_gid; |
| mode_t tty_mode; |
| int n_bytes; |
| |
| /* |
| * Cancel the alarm we set to limit the time taken for |
| * authentication. |
| */ |
| alarm(0); |
| |
| /* |
| * Inform the channel mechanism that we are the server side and that |
| * the client may request to connect to any port at all. (The user |
| * could do it anyway, and we wouldn\'t know what is permitted except |
| * by the client telling us, so we can equally well trust the client |
| * not to request anything bogus.) |
| */ |
| channel_permit_all_opens(); |
| |
| /* |
| * We stay in this loop until the client requests to execute a shell |
| * or a command. |
| */ |
| while (1) { |
| int plen, dlen; |
| |
| /* Get a packet from the client. */ |
| type = packet_read(&plen); |
| |
| /* Process the packet. */ |
| switch (type) { |
| case SSH_CMSG_REQUEST_COMPRESSION: |
| packet_integrity_check(plen, 4, type); |
| compression_level = packet_get_int(); |
| if (compression_level < 1 || compression_level > 9) { |
| packet_send_debug("Received illegal compression level %d.", |
| compression_level); |
| goto fail; |
| } |
| /* Enable compression after we have responded with SUCCESS. */ |
| enable_compression_after_reply = 1; |
| break; |
| |
| case SSH_CMSG_REQUEST_PTY: |
| if (no_pty_flag) { |
| debug("Allocating a pty not permitted for this authentication."); |
| goto fail; |
| } |
| if (have_pty) |
| packet_disconnect("Protocol error: you already have a pty."); |
| |
| debug("Allocating pty."); |
| |
| /* Allocate a pty and open it. */ |
| if (!pty_allocate(&ptyfd, &ttyfd, ttyname, |
| sizeof(ttyname))) { |
| error("Failed to allocate pty."); |
| goto fail; |
| } |
| /* Determine the group to make the owner of the tty. */ |
| grp = getgrnam("tty"); |
| if (grp) { |
| tty_gid = grp->gr_gid; |
| tty_mode = S_IRUSR | S_IWUSR | S_IWGRP; |
| } else { |
| tty_gid = pw->pw_gid; |
| tty_mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; |
| } |
| |
| /* Change ownership of the tty. */ |
| if (chown(ttyname, pw->pw_uid, tty_gid) < 0) |
| fatal("chown(%.100s, %d, %d) failed: %.100s", |
| ttyname, pw->pw_uid, tty_gid, strerror(errno)); |
| if (chmod(ttyname, tty_mode) < 0) |
| fatal("chmod(%.100s, 0%o) failed: %.100s", |
| ttyname, tty_mode, strerror(errno)); |
| |
| /* Get TERM from the packet. Note that the value may be of arbitrary length. */ |
| term = packet_get_string(&dlen); |
| packet_integrity_check(dlen, strlen(term), type); |
| /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ |
| /* Remaining bytes */ |
| n_bytes = plen - (4 + dlen + 4 * 4); |
| |
| if (strcmp(term, "") == 0) |
| term = NULL; |
| |
| /* Get window size from the packet. */ |
| row = packet_get_int(); |
| col = packet_get_int(); |
| xpixel = packet_get_int(); |
| ypixel = packet_get_int(); |
| pty_change_window_size(ptyfd, row, col, xpixel, ypixel); |
| |
| /* Get tty modes from the packet. */ |
| tty_parse_modes(ttyfd, &n_bytes); |
| packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type); |
| |
| /* Indicate that we now have a pty. */ |
| have_pty = 1; |
| |
| #ifdef USE_PAM |
| /* do the pam_open_session since we have the pty */ |
| do_pam_session(pw->pw_name, ttyname); |
| #endif /* USE_PAM */ |
| |
| break; |
| |
| case SSH_CMSG_X11_REQUEST_FORWARDING: |
| if (!options.x11_forwarding) { |
| packet_send_debug("X11 forwarding disabled in server configuration file."); |
| goto fail; |
| } |
| #ifdef XAUTH_PATH |
| if (no_x11_forwarding_flag) { |
| packet_send_debug("X11 forwarding not permitted for this authentication."); |
| goto fail; |
| } |
| debug("Received request for X11 forwarding with auth spoofing."); |
| if (display) |
| packet_disconnect("Protocol error: X11 display already set."); |
| { |
| int proto_len, data_len; |
| proto = packet_get_string(&proto_len); |
| data = packet_get_string(&data_len); |
| packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type); |
| } |
| if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER) |
| screen = packet_get_int(); |
| else |
| screen = 0; |
| display = x11_create_display_inet(screen, options.x11_display_offset); |
| if (!display) |
| goto fail; |
| |
| /* Setup to always have a local .Xauthority. */ |
| xauthfile = xmalloc(MAXPATHLEN); |
| snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX"); |
| |
| if ((xauthfd = mkstemp(xauthfile)) != -1) { |
| fchown(xauthfd, pw->pw_uid, pw->pw_gid); |
| close(xauthfd); |
| fatal_add_cleanup(xauthfile_cleanup_proc, NULL); |
| } else { |
| xfree(xauthfile); |
| xauthfile = NULL; |
| } |
| break; |
| #else /* XAUTH_PATH */ |
| packet_send_debug("No xauth program; cannot forward with spoofing."); |
| goto fail; |
| #endif /* XAUTH_PATH */ |
| |
| case SSH_CMSG_AGENT_REQUEST_FORWARDING: |
| if (no_agent_forwarding_flag || compat13) { |
| debug("Authentication agent forwarding not permitted for this authentication."); |
| goto fail; |
| } |
| debug("Received authentication agent forwarding request."); |
| auth_input_request_forwarding(pw); |
| break; |
| |
| case SSH_CMSG_PORT_FORWARD_REQUEST: |
| if (no_port_forwarding_flag) { |
| debug("Port forwarding not permitted for this authentication."); |
| goto fail; |
| } |
| debug("Received TCP/IP port forwarding request."); |
| channel_input_port_forward_request(pw->pw_uid == 0); |
| break; |
| |
| case SSH_CMSG_MAX_PACKET_SIZE: |
| if (packet_set_maxsize(packet_get_int()) < 0) |
| goto fail; |
| break; |
| |
| case SSH_CMSG_EXEC_SHELL: |
| /* Set interactive/non-interactive mode. */ |
| packet_set_interactive(have_pty || display != NULL, |
| options.keepalives); |
| |
| #ifdef USE_PAM |
| do_pam_setcred(); |
| #endif /* USE_PAM */ |
| if (forced_command != NULL) |
| goto do_forced_command; |
| debug("Forking shell."); |
| packet_integrity_check(plen, 0, type); |
| if (have_pty) |
| do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); |
| else |
| do_exec_no_pty(NULL, pw, display, proto, data); |
| return; |
| |
| case SSH_CMSG_EXEC_CMD: |
| /* Set interactive/non-interactive mode. */ |
| packet_set_interactive(have_pty || display != NULL, |
| options.keepalives); |
| |
| #ifdef USE_PAM |
| do_pam_setcred(); |
| #endif /* USE_PAM */ |
| if (forced_command != NULL) |
| goto do_forced_command; |
| /* Get command from the packet. */ |
| { |
| int dlen; |
| command = packet_get_string(&dlen); |
| debug("Executing command '%.500s'", command); |
| packet_integrity_check(plen, 4 + dlen, type); |
| } |
| if (have_pty) |
| do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); |
| else |
| do_exec_no_pty(command, pw, display, proto, data); |
| xfree(command); |
| return; |
| |
| default: |
| /* |
| * Any unknown messages in this phase are ignored, |
| * and a failure message is returned. |
| */ |
| log("Unknown packet type received after authentication: %d", type); |
| goto fail; |
| } |
| |
| /* The request was successfully processed. */ |
| packet_start(SSH_SMSG_SUCCESS); |
| packet_send(); |
| packet_write_wait(); |
| |
| /* Enable compression now that we have replied if appropriate. */ |
| if (enable_compression_after_reply) { |
| enable_compression_after_reply = 0; |
| packet_start_compression(compression_level); |
| } |
| continue; |
| |
| fail: |
| /* The request failed. */ |
| packet_start(SSH_SMSG_FAILURE); |
| packet_send(); |
| packet_write_wait(); |
| continue; |
| |
| do_forced_command: |
| /* |
| * There is a forced command specified for this login. |
| * Execute it. |
| */ |
| debug("Executing forced command: %.900s", forced_command); |
| if (have_pty) |
| do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data); |
| else |
| do_exec_no_pty(forced_command, pw, display, proto, data); |
| return; |
| } |
| } |
| |
| /* |
| * This is called to fork and execute a command when we have no tty. This |
| * will call do_child from the child, and server_loop from the parent after |
| * setting up file descriptors and such. |
| */ |
| void |
| do_exec_no_pty(const char *command, struct passwd * pw, |
| const char *display, const char *auth_proto, |
| const char *auth_data) |
| { |
| int pid; |
| |
| #ifdef USE_PIPES |
| int pin[2], pout[2], perr[2]; |
| /* Allocate pipes for communicating with the program. */ |
| if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) |
| packet_disconnect("Could not create pipes: %.100s", |
| strerror(errno)); |
| #else /* USE_PIPES */ |
| int inout[2], err[2]; |
| /* Uses socket pairs to communicate with the program. */ |
| if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 || |
| socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) |
| packet_disconnect("Could not create socket pairs: %.100s", |
| strerror(errno)); |
| #endif /* USE_PIPES */ |
| |
| setproctitle("%s@notty", pw->pw_name); |
| |
| /* Fork the child. */ |
| if ((pid = fork()) == 0) { |
| /* Child. Reinitialize the log since the pid has changed. */ |
| log_init(av0, options.log_level, options.log_facility, log_stderr); |
| |
| /* |
| * Create a new session and process group since the 4.4BSD |
| * setlogin() affects the entire process group. |
| */ |
| if (setsid() < 0) |
| error("setsid failed: %.100s", strerror(errno)); |
| |
| #ifdef USE_PIPES |
| /* |
| * Redirect stdin. We close the parent side of the socket |
| * pair, and make the child side the standard input. |
| */ |
| close(pin[1]); |
| if (dup2(pin[0], 0) < 0) |
| perror("dup2 stdin"); |
| close(pin[0]); |
| |
| /* Redirect stdout. */ |
| close(pout[0]); |
| if (dup2(pout[1], 1) < 0) |
| perror("dup2 stdout"); |
| close(pout[1]); |
| |
| /* Redirect stderr. */ |
| close(perr[0]); |
| if (dup2(perr[1], 2) < 0) |
| perror("dup2 stderr"); |
| close(perr[1]); |
| #else /* USE_PIPES */ |
| /* |
| * Redirect stdin, stdout, and stderr. Stdin and stdout will |
| * use the same socket, as some programs (particularly rdist) |
| * seem to depend on it. |
| */ |
| close(inout[1]); |
| close(err[1]); |
| if (dup2(inout[0], 0) < 0) /* stdin */ |
| perror("dup2 stdin"); |
| if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */ |
| perror("dup2 stdout"); |
| if (dup2(err[0], 2) < 0) /* stderr */ |
| perror("dup2 stderr"); |
| #endif /* USE_PIPES */ |
| |
| /* Do processing for the child (exec command etc). */ |
| do_child(command, pw, NULL, display, auth_proto, auth_data, NULL); |
| /* NOTREACHED */ |
| } |
| if (pid < 0) |
| packet_disconnect("fork failed: %.100s", strerror(errno)); |
| #ifdef USE_PIPES |
| /* We are the parent. Close the child sides of the pipes. */ |
| close(pin[0]); |
| close(pout[1]); |
| close(perr[1]); |
| |
| /* Enter the interactive session. */ |
| server_loop(pid, pin[1], pout[0], perr[0]); |
| /* server_loop has closed pin[1], pout[1], and perr[1]. */ |
| #else /* USE_PIPES */ |
| /* We are the parent. Close the child sides of the socket pairs. */ |
| close(inout[0]); |
| close(err[0]); |
| |
| /* |
| * Enter the interactive session. Note: server_loop must be able to |
| * handle the case that fdin and fdout are the same. |
| */ |
| server_loop(pid, inout[1], inout[1], err[1]); |
| /* server_loop has closed inout[1] and err[1]. */ |
| #endif /* USE_PIPES */ |
| } |
| |
| struct pty_cleanup_context { |
| const char *ttyname; |
| int pid; |
| }; |
| |
| /* |
| * Function to perform cleanup if we get aborted abnormally (e.g., due to a |
| * dropped connection). |
| */ |
| void |
| pty_cleanup_proc(void *context) |
| { |
| struct pty_cleanup_context *cu = context; |
| |
| debug("pty_cleanup_proc called"); |
| |
| /* Record that the user has logged out. */ |
| record_logout(cu->pid, cu->ttyname); |
| |
| /* Release the pseudo-tty. */ |
| pty_release(cu->ttyname); |
| } |
| |
| /* |
| * This is called to fork and execute a command when we have a tty. This |
| * will call do_child from the child, and server_loop from the parent after |
| * setting up file descriptors, controlling tty, updating wtmp, utmp, |
| * lastlog, and other such operations. |
| */ |
| void |
| do_exec_pty(const char *command, int ptyfd, int ttyfd, |
| const char *ttyname, struct passwd * pw, const char *term, |
| const char *display, const char *auth_proto, |
| const char *auth_data) |
| { |
| int pid, fdout; |
| const char *hostname; |
| time_t last_login_time; |
| char buf[100], *time_string; |
| FILE *f; |
| char line[256]; |
| struct stat st; |
| int quiet_login; |
| struct sockaddr_storage from; |
| socklen_t fromlen; |
| struct pty_cleanup_context cleanup_context; |
| |
| /* Get remote host name. */ |
| hostname = get_canonical_hostname(); |
| |
| /* |
| * Get the time when the user last logged in. Buf will be set to |
| * contain the hostname the last login was from. |
| */ |
| if (!options.use_login) { |
| last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, |
| buf, sizeof(buf)); |
| } |
| setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1); |
| |
| /* Fork the child. */ |
| if ((pid = fork()) == 0) { |
| pid = getpid(); |
| |
| /* Child. Reinitialize the log because the pid has |
| changed. */ |
| log_init(av0, options.log_level, options.log_facility, log_stderr); |
| |
| /* Close the master side of the pseudo tty. */ |
| close(ptyfd); |
| |
| /* Make the pseudo tty our controlling tty. */ |
| pty_make_controlling_tty(&ttyfd, ttyname); |
| |
| /* Redirect stdin from the pseudo tty. */ |
| if (dup2(ttyfd, fileno(stdin)) < 0) |
| error("dup2 stdin failed: %.100s", strerror(errno)); |
| |
| /* Redirect stdout to the pseudo tty. */ |
| if (dup2(ttyfd, fileno(stdout)) < 0) |
| error("dup2 stdin failed: %.100s", strerror(errno)); |
| |
| /* Redirect stderr to the pseudo tty. */ |
| if (dup2(ttyfd, fileno(stderr)) < 0) |
| error("dup2 stdin failed: %.100s", strerror(errno)); |
| |
| /* Close the extra descriptor for the pseudo tty. */ |
| close(ttyfd); |
| |
| /* |
| * Get IP address of client. This is needed because we want |
| * to record where the user logged in from. If the |
| * connection is not a socket, let the ip address be 0.0.0.0. |
| */ |
| memset(&from, 0, sizeof(from)); |
| if (packet_get_connection_in() == packet_get_connection_out()) { |
| fromlen = sizeof(from); |
| if (getpeername(packet_get_connection_in(), |
| (struct sockaddr *) & from, &fromlen) < 0) { |
| debug("getpeername: %.100s", strerror(errno)); |
| fatal_cleanup(); |
| } |
| } |
| /* Record that there was a login on that terminal. */ |
| record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname, |
| (struct sockaddr *)&from); |
| |
| /* Check if .hushlogin exists. */ |
| snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir); |
| quiet_login = stat(line, &st) >= 0; |
| |
| #ifdef USE_PAM |
| if (!quiet_login) |
| print_pam_messages(); |
| #endif /* USE_PAM */ |
| |
| /* |
| * If the user has logged in before, display the time of last |
| * login. However, don't display anything extra if a command |
| * has been specified (so that ssh can be used to execute |
| * commands on a remote machine without users knowing they |
| * are going to another machine). Login(1) will do this for |
| * us as well, so check if login(1) is used |
| */ |
| if (command == NULL && last_login_time != 0 && !quiet_login && |
| !options.use_login) { |
| /* Convert the date to a string. */ |
| time_string = ctime(&last_login_time); |
| /* Remove the trailing newline. */ |
| if (strchr(time_string, '\n')) |
| *strchr(time_string, '\n') = 0; |
| /* Display the last login time. Host if displayed |
| if known. */ |
| if (strcmp(buf, "") == 0) |
| printf("Last login: %s\r\n", time_string); |
| else |
| printf("Last login: %s from %s\r\n", time_string, buf); |
| } |
| /* |
| * Print /etc/motd unless a command was specified or printing |
| * it was disabled in server options or login(1) will be |
| * used. Note that some machines appear to print it in |
| * /etc/profile or similar. |
| */ |
| if (command == NULL && options.print_motd && !quiet_login && |
| !options.use_login) { |
| /* Print /etc/motd if it exists. */ |
| f = fopen("/etc/motd", "r"); |
| if (f) { |
| while (fgets(line, sizeof(line), f)) |
| fputs(line, stdout); |
| fclose(f); |
| } |
| } |
| /* Do common processing for the child, such as execing the command. */ |
| do_child(command, pw, term, display, auth_proto, auth_data, ttyname); |
| /* NOTREACHED */ |
| } |
| if (pid < 0) |
| packet_disconnect("fork failed: %.100s", strerror(errno)); |
| /* Parent. Close the slave side of the pseudo tty. */ |
| close(ttyfd); |
| |
| /* |
| * Create another descriptor of the pty master side for use as the |
| * standard input. We could use the original descriptor, but this |
| * simplifies code in server_loop. The descriptor is bidirectional. |
| */ |
| fdout = dup(ptyfd); |
| if (fdout < 0) |
| packet_disconnect("dup failed: %.100s", strerror(errno)); |
| |
| /* |
| * Add a cleanup function to clear the utmp entry and record logout |
| * time in case we call fatal() (e.g., the connection gets closed). |
| */ |
| cleanup_context.pid = pid; |
| cleanup_context.ttyname = ttyname; |
| fatal_add_cleanup(pty_cleanup_proc, (void *) &cleanup_context); |
| |
| /* Enter interactive session. */ |
| server_loop(pid, ptyfd, fdout, -1); |
| /* server_loop has not closed ptyfd and fdout. */ |
| |
| /* Cancel the cleanup function. */ |
| fatal_remove_cleanup(pty_cleanup_proc, (void *) &cleanup_context); |
| |
| /* Record that the user has logged out. */ |
| record_logout(pid, ttyname); |
| |
| /* Release the pseudo-tty. */ |
| pty_release(ttyname); |
| |
| /* |
| * Close the server side of the socket pairs. We must do this after |
| * the pty cleanup, so that another process doesn't get this pty |
| * while we're still cleaning up. |
| */ |
| close(ptyfd); |
| close(fdout); |
| } |
| |
| /* |
| * Sets the value of the given variable in the environment. If the variable |
| * already exists, its value is overriden. |
| */ |
| void |
| child_set_env(char ***envp, unsigned int *envsizep, const char *name, |
| const char *value) |
| { |
| unsigned int i, namelen; |
| char **env; |
| |
| /* |
| * Find the slot where the value should be stored. If the variable |
| * already exists, we reuse the slot; otherwise we append a new slot |
| * at the end of the array, expanding if necessary. |
| */ |
| env = *envp; |
| namelen = strlen(name); |
| for (i = 0; env[i]; i++) |
| if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=') |
| break; |
| if (env[i]) { |
| /* Reuse the slot. */ |
| xfree(env[i]); |
| } else { |
| /* New variable. Expand if necessary. */ |
| if (i >= (*envsizep) - 1) { |
| (*envsizep) += 50; |
| env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *)); |
| } |
| /* Need to set the NULL pointer at end of array beyond the new slot. */ |
| env[i + 1] = NULL; |
| } |
| |
| /* Allocate space and format the variable in the appropriate slot. */ |
| env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1); |
| snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value); |
| } |
| |
| /* |
| * Reads environment variables from the given file and adds/overrides them |
| * into the environment. If the file does not exist, this does nothing. |
| * Otherwise, it must consist of empty lines, comments (line starts with '#') |
| * and assignments of the form name=value. No other forms are allowed. |
| */ |
| void |
| read_environment_file(char ***env, unsigned int *envsize, |
| const char *filename) |
| { |
| FILE *f; |
| char buf[4096]; |
| char *cp, *value; |
| |
| f = fopen(filename, "r"); |
| if (!f) |
| return; |
| |
| while (fgets(buf, sizeof(buf), f)) { |
| for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) |
| ; |
| if (!*cp || *cp == '#' || *cp == '\n') |
| continue; |
| if (strchr(cp, '\n')) |
| *strchr(cp, '\n') = '\0'; |
| value = strchr(cp, '='); |
| if (value == NULL) { |
| fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf); |
| continue; |
| } |
| /* Replace the equals sign by nul, and advance value to the value string. */ |
| *value = '\0'; |
| value++; |
| child_set_env(env, envsize, cp, value); |
| } |
| fclose(f); |
| } |
| |
| #ifdef USE_PAM |
| /* |
| * Sets any environment variables which have been specified by PAM |
| */ |
| void do_pam_environment(char ***env, int *envsize) |
| { |
| char *equals, var_name[512], var_val[512]; |
| char **pam_env; |
| int i; |
| |
| if ((pam_env = fetch_pam_environment()) == NULL) |
| return; |
| |
| for(i = 0; pam_env[i] != NULL; i++) { |
| if ((equals = strstr(pam_env[i], "=")) == NULL) |
| continue; |
| |
| if (strlen(pam_env[i]) < (sizeof(var_name) - 1)) |
| { |
| memset(var_name, '\0', sizeof(var_name)); |
| memset(var_val, '\0', sizeof(var_val)); |
| |
| strncpy(var_name, pam_env[i], equals - pam_env[i]); |
| strcpy(var_val, equals + 1); |
| |
| debug("PAM environment: %s=%s", var_name, var_val); |
| |
| child_set_env(env, envsize, var_name, var_val); |
| } |
| } |
| } |
| #endif /* USE_PAM */ |
| |
| /* |
| * Performs common processing for the child, such as setting up the |
| * environment, closing extra file descriptors, setting the user and group |
| * ids, and executing the command or shell. |
| */ |
| void |
| do_child(const char *command, struct passwd * pw, const char *term, |
| const char *display, const char *auth_proto, |
| const char *auth_data, const char *ttyname) |
| { |
| const char *shell, *cp = NULL; |
| char buf[256]; |
| FILE *f; |
| unsigned int envsize, i; |
| char **env; |
| extern char **environ; |
| struct stat st; |
| char *argv[10]; |
| |
| #ifndef USE_PAM /* pam_nologin handles this */ |
| /* Check /etc/nologin. */ |
| f = fopen("/etc/nologin", "r"); |
| if (f) { |
| /* /etc/nologin exists. Print its contents and exit. */ |
| while (fgets(buf, sizeof(buf), f)) |
| fputs(buf, stderr); |
| fclose(f); |
| if (pw->pw_uid != 0) |
| exit(254); |
| } |
| #endif /* USE_PAM */ |
| |
| /* Set login name in the kernel. */ |
| if (setlogin(pw->pw_name) < 0) |
| error("setlogin failed: %s", strerror(errno)); |
| |
| /* Set uid, gid, and groups. */ |
| /* Login(1) does this as well, and it needs uid 0 for the "-h" |
| switch, so we let login(1) to this for us. */ |
| if (!options.use_login) { |
| if (getuid() == 0 || geteuid() == 0) { |
| if (setgid(pw->pw_gid) < 0) { |
| perror("setgid"); |
| exit(1); |
| } |
| /* Initialize the group list. */ |
| if (initgroups(pw->pw_name, pw->pw_gid) < 0) { |
| perror("initgroups"); |
| exit(1); |
| } |
| endgrent(); |
| |
| /* Permanently switch to the desired uid. */ |
| permanently_set_uid(pw->pw_uid); |
| } |
| if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) |
| fatal("Failed to set uids to %d.", (int) pw->pw_uid); |
| } |
| /* |
| * Get the shell from the password data. An empty shell field is |
| * legal, and means /bin/sh. |
| */ |
| shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; |
| |
| #ifdef AFS |
| /* Try to get AFS tokens for the local cell. */ |
| if (k_hasafs()) { |
| char cell[64]; |
| |
| if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0) |
| krb_afslog(cell, 0); |
| |
| krb_afslog(0, 0); |
| } |
| #endif /* AFS */ |
| |
| /* Initialize the environment. */ |
| envsize = 100; |
| env = xmalloc(envsize * sizeof(char *)); |
| env[0] = NULL; |
| |
| if (!options.use_login) { |
| /* Set basic environment. */ |
| child_set_env(&env, &envsize, "USER", pw->pw_name); |
| child_set_env(&env, &envsize, "LOGNAME", pw->pw_name); |
| child_set_env(&env, &envsize, "HOME", pw->pw_dir); |
| child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); |
| |
| snprintf(buf, sizeof buf, "%.200s/%.50s", |
| _PATH_MAILDIR, pw->pw_name); |
| child_set_env(&env, &envsize, "MAIL", buf); |
| |
| /* Normal systems set SHELL by default. */ |
| child_set_env(&env, &envsize, "SHELL", shell); |
| } |
| if (getenv("TZ")) |
| child_set_env(&env, &envsize, "TZ", getenv("TZ")); |
| |
| /* Set custom environment options from RSA authentication. */ |
| while (custom_environment) { |
| struct envstring *ce = custom_environment; |
| char *s = ce->s; |
| int i; |
| for (i = 0; s[i] != '=' && s[i]; i++); |
| if (s[i] == '=') { |
| s[i] = 0; |
| child_set_env(&env, &envsize, s, s + i + 1); |
| } |
| custom_environment = ce->next; |
| xfree(ce->s); |
| xfree(ce); |
| } |
| |
| snprintf(buf, sizeof buf, "%.50s %d %d", |
| get_remote_ipaddr(), get_remote_port(), get_local_port()); |
| child_set_env(&env, &envsize, "SSH_CLIENT", buf); |
| |
| if (ttyname) |
| child_set_env(&env, &envsize, "SSH_TTY", ttyname); |
| if (term) |
| child_set_env(&env, &envsize, "TERM", term); |
| if (display) |
| child_set_env(&env, &envsize, "DISPLAY", display); |
| |
| #ifdef _AIX |
| { |
| char *authstate,*krb5cc; |
| |
| if ((authstate = getenv("AUTHSTATE")) != NULL) |
| child_set_env(&env,&envsize,"AUTHSTATE",authstate); |
| |
| if ((krb5cc = getenv("KRB5CCNAME")) != NULL) |
| child_set_env(&env,&envsize,"KRB5CCNAME",krb5cc); |
| } |
| #endif |
| |
| #ifdef KRB4 |
| { |
| extern char *ticket; |
| |
| if (ticket) |
| child_set_env(&env, &envsize, "KRBTKFILE", ticket); |
| } |
| #endif /* KRB4 */ |
| |
| #ifdef USE_PAM |
| /* Pull in any environment variables that may have been set by PAM. */ |
| do_pam_environment(&env, &envsize); |
| #endif /* USE_PAM */ |
| |
| if (xauthfile) |
| child_set_env(&env, &envsize, "XAUTHORITY", xauthfile); |
| |
| if (auth_get_socket_name() != NULL) |
| child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, |
| auth_get_socket_name()); |
| |
| read_environment_file(&env,&envsize,"/etc/environment"); |
| |
| /* read $HOME/.ssh/environment. */ |
| if (!options.use_login) { |
| snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir); |
| read_environment_file(&env, &envsize, buf); |
| } |
| if (debug_flag) { |
| /* dump the environment */ |
| fprintf(stderr, "Environment:\n"); |
| for (i = 0; env[i]; i++) |
| fprintf(stderr, " %.200s\n", env[i]); |
| } |
| /* |
| * Close the connection descriptors; note that this is the child, and |
| * the server will still have the socket open, and it is important |
| * that we do not shutdown it. Note that the descriptors cannot be |
| * closed before building the environment, as we call |
| * get_remote_ipaddr there. |
| */ |
| if (packet_get_connection_in() == packet_get_connection_out()) |
| close(packet_get_connection_in()); |
| else { |
| close(packet_get_connection_in()); |
| close(packet_get_connection_out()); |
| } |
| /* |
| * Close all descriptors related to channels. They will still remain |
| * open in the parent. |
| */ |
| /* XXX better use close-on-exec? -markus */ |
| channel_close_all(); |
| |
| /* |
| * Close any extra file descriptors. Note that there may still be |
| * descriptors left by system functions. They will be closed later. |
| */ |
| endpwent(); |
| |
| /* |
| * Close any extra open file descriptors so that we don\'t have them |
| * hanging around in clients. Note that we want to do this after |
| * initgroups, because at least on Solaris 2.3 it leaves file |
| * descriptors open. |
| */ |
| for (i = 3; i < 64; i++) |
| close(i); |
| |
| /* Change current directory to the user\'s home directory. */ |
| if (chdir(pw->pw_dir) < 0) |
| fprintf(stderr, "Could not chdir to home directory %s: %s\n", |
| pw->pw_dir, strerror(errno)); |
| |
| /* |
| * Must take new environment into use so that .ssh/rc, /etc/sshrc and |
| * xauth are run in the proper environment. |
| */ |
| environ = env; |
| |
| /* |
| * Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first |
| * in this order). |
| */ |
| if (!options.use_login) { |
| if (stat(SSH_USER_RC, &st) >= 0) { |
| if (debug_flag) |
| fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC); |
| |
| f = popen("/bin/sh " SSH_USER_RC, "w"); |
| if (f) { |
| if (auth_proto != NULL && auth_data != NULL) |
| fprintf(f, "%s %s\n", auth_proto, auth_data); |
| pclose(f); |
| } else |
| fprintf(stderr, "Could not run %s\n", SSH_USER_RC); |
| } else if (stat(SSH_SYSTEM_RC, &st) >= 0) { |
| if (debug_flag) |
| fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC); |
| |
| f = popen("/bin/sh " SSH_SYSTEM_RC, "w"); |
| if (f) { |
| if (auth_proto != NULL && auth_data != NULL) |
| fprintf(f, "%s %s\n", auth_proto, auth_data); |
| pclose(f); |
| } else |
| fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC); |
| } |
| #ifdef XAUTH_PATH |
| else { |
| /* Add authority data to .Xauthority if appropriate. */ |
| if (auth_proto != NULL && auth_data != NULL) { |
| if (debug_flag) |
| fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", |
| XAUTH_PATH, display, auth_proto, auth_data); |
| |
| f = popen(XAUTH_PATH " -q -", "w"); |
| if (f) { |
| fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); |
| fclose(f); |
| } else |
| fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH); |
| } |
| } |
| #endif /* XAUTH_PATH */ |
| |
| /* Get the last component of the shell name. */ |
| cp = strrchr(shell, '/'); |
| if (cp) |
| cp++; |
| else |
| cp = shell; |
| } |
| /* |
| * If we have no command, execute the shell. In this case, the shell |
| * name to be passed in argv[0] is preceded by '-' to indicate that |
| * this is a login shell. |
| */ |
| if (!command) { |
| if (!options.use_login) { |
| char buf[256]; |
| |
| /* |
| * Check for mail if we have a tty and it was enabled |
| * in server options. |
| */ |
| if (ttyname && options.check_mail) { |
| char *mailbox; |
| struct stat mailstat; |
| mailbox = getenv("MAIL"); |
| if (mailbox != NULL) { |
| if (stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0) |
| printf("No mail.\n"); |
| else if (mailstat.st_mtime < mailstat.st_atime) |
| printf("You have mail.\n"); |
| else |
| printf("You have new mail.\n"); |
| } |
| } |
| /* Start the shell. Set initial character to '-'. */ |
| buf[0] = '-'; |
| strncpy(buf + 1, cp, sizeof(buf) - 1); |
| buf[sizeof(buf) - 1] = 0; |
| |
| /* Execute the shell. */ |
| argv[0] = buf; |
| argv[1] = NULL; |
| execve(shell, argv, env); |
| |
| /* Executing the shell failed. */ |
| perror(shell); |
| exit(1); |
| |
| } else { |
| /* Launch login(1). */ |
| |
| execl(LOGIN_PROGRAM, "login", "-h", get_remote_ipaddr(), |
| "-p", "-f", "--", pw->pw_name, NULL); |
| |
| /* Login couldn't be executed, die. */ |
| |
| perror("login"); |
| exit(1); |
| } |
| } |
| /* |
| * Execute the command using the user's shell. This uses the -c |
| * option to execute the command. |
| */ |
| argv[0] = (char *) cp; |
| argv[1] = "-c"; |
| argv[2] = (char *) command; |
| argv[3] = NULL; |
| execve(shell, argv, env); |
| perror(shell); |
| exit(1); |
| } |