diff options
Diffstat (limited to 'ssh.c')
| -rw-r--r-- | ssh.c | 1387 |
1 files changed, 664 insertions, 723 deletions
@@ -1,24 +1,17 @@ /* - -ssh.c - -Author: Tatu Ylonen <ylo@cs.hut.fi> - -Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland - All rights reserved - -Created: Sat Mar 18 16:36:11 1995 ylo - -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. - -Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada. - -*/ + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * Created: Sat Mar 18 16:36:11 1995 ylo + * 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. + * + * Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada. + */ #include "includes.h" -RCSID("$Id: ssh.c,v 1.10 1999/11/16 02:37:16 damien Exp $"); +RCSID("$Id: ssh.c,v 1.11 1999/11/24 13:26:23 damien Exp $"); #include "xmalloc.h" #include "ssh.h" @@ -34,13 +27,11 @@ extern char *__progname; const char *__progname = "ssh"; #endif /* HAVE___PROGNAME */ -/* Flag indicating whether debug mode is on. This can be set on the - command line. */ +/* Flag indicating whether debug mode is on. This can be set on the command line. */ int debug_flag = 0; -/* Flag indicating whether to allocate a pseudo tty. This can be set on the - command line, and is automatically set if no command is given on the command - line. */ +/* Flag indicating whether to allocate a pseudo tty. This can be set on the command + line, and is automatically set if no command is given on the command line. */ int tty_flag = 0; /* Flag indicating that nothing should be read from stdin. This can be set @@ -87,730 +78,680 @@ uid_t original_real_uid; void usage() { - fprintf(stderr, "Usage: %s [options] host [command]\n", av0); - fprintf(stderr, "Options:\n"); - fprintf(stderr, " -l user Log in using this user name.\n"); - fprintf(stderr, " -n Redirect input from /dev/null.\n"); - fprintf(stderr, " -a Disable authentication agent forwarding.\n"); + fprintf(stderr, "Usage: %s [options] host [command]\n", av0); + fprintf(stderr, "Options:\n"); + fprintf(stderr, " -l user Log in using this user name.\n"); + fprintf(stderr, " -n Redirect input from /dev/null.\n"); + fprintf(stderr, " -a Disable authentication agent forwarding.\n"); #ifdef AFS - fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); -#endif /* AFS */ - fprintf(stderr, " -x Disable X11 connection forwarding.\n"); - fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); - fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); - fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); - fprintf(stderr, " -V Display version number only.\n"); - fprintf(stderr, " -P Don't allocate a privileged port.\n"); - fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); - fprintf(stderr, " -f Fork into background after authentication.\n"); - fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); - - fprintf(stderr, " -c cipher Select encryption algorithm: " - "``3des'', " - "``blowfish''\n"); - fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); - fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); - fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); - fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); - fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); - fprintf(stderr, " -C Enable compression.\n"); - fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); - fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); - exit(1); + fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n"); +#endif /* AFS */ + fprintf(stderr, " -x Disable X11 connection forwarding.\n"); + fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n"); + fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n"); + fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); + fprintf(stderr, " -V Display version number only.\n"); + fprintf(stderr, " -P Don't allocate a privileged port.\n"); + fprintf(stderr, " -q Quiet; don't display any warning messages.\n"); + fprintf(stderr, " -f Fork into background after authentication.\n"); + fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n"); + + fprintf(stderr, " -c cipher Select encryption algorithm: " + "``3des'', " + "``blowfish''\n"); + fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n"); + fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n"); + fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n"); + fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0); + fprintf(stderr, " forward them to the other side by connecting to host:port.\n"); + fprintf(stderr, " -C Enable compression.\n"); + fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n"); + fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n"); + exit(1); } -/* Connects to the given host using rsh (or prints an error message and exits - if rsh is not available). This function never returns. */ - +/* + * Connects to the given host using rsh (or prints an error message and exits + * if rsh is not available). This function never returns. + */ void -rsh_connect(char *host, char *user, Buffer *command) +rsh_connect(char *host, char *user, Buffer * command) { - char *args[10]; - int i; - - log("Using rsh. WARNING: Connection will not be encrypted."); - /* Build argument list for rsh. */ - i = 0; - args[i++] = _PATH_RSH; - args[i++] = host; /* may have to come after user on some systems */ - if (user) - { - args[i++] = "-l"; - args[i++] = user; - } - if (buffer_len(command) > 0) - { - buffer_append(command, "\0", 1); - args[i++] = buffer_ptr(command); - } - args[i++] = NULL; - if (debug_flag) - { - for (i = 0; args[i]; i++) - { - if (i != 0) - fprintf(stderr, " "); - fprintf(stderr, "%s", args[i]); + char *args[10]; + int i; + + log("Using rsh. WARNING: Connection will not be encrypted."); + /* Build argument list for rsh. */ + i = 0; + args[i++] = _PATH_RSH; + /* host may have to come after user on some systems */ + args[i++] = host; + if (user) { + args[i++] = "-l"; + args[i++] = user; + } + if (buffer_len(command) > 0) { + buffer_append(command, "\0", 1); + args[i++] = buffer_ptr(command); + } + args[i++] = NULL; + if (debug_flag) { + for (i = 0; args[i]; i++) { + if (i != 0) + fprintf(stderr, " "); + fprintf(stderr, "%s", args[i]); + } + fprintf(stderr, "\n"); } - fprintf(stderr, "\n"); - } - execv(_PATH_RSH, args); - perror(_PATH_RSH); - exit(1); + execv(_PATH_RSH, args); + perror(_PATH_RSH); + exit(1); } -/* Main program for the ssh client. */ - +/* + * Main program for the ssh client. + */ int main(int ac, char **av) { - int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, authfd; - char *optarg, *cp, buf[256]; - Buffer command; - struct winsize ws; - struct stat st; - struct passwd *pw, pwcopy; - int interactive = 0, dummy; - uid_t original_effective_uid; - int plen; - - /* 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(); - - /* 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)); - } - - /* 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). */ - temporarily_use_uid(original_real_uid); - - /* 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); - - /* Save our own name. */ - av0 = av[0]; - - /* Initialize option structure to indicate that no values have been set. */ - initialize_options(&options); - - /* Parse command-line arguments. */ - host = NULL; - - /* If program name is not one of the standard names, use it as host name. */ - if (strchr(av0, '/')) - cp = strrchr(av0, '/') + 1; - else - cp = av0; - if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && - strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) - host = cp; - - for (optind = 1; optind < ac; optind++) - { - if (av[optind][0] != '-') - { - if (host) - break; - if ((cp = strchr(av[optind], '@'))) { - options.user = av[optind]; - *cp = '\0'; - host = ++cp; - } - else - host = av[optind]; - continue; + int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port, + authfd; + char *optarg, *cp, buf[256]; + Buffer command; + struct winsize ws; + struct stat st; + struct passwd *pw, pwcopy; + int interactive = 0, dummy; + uid_t original_effective_uid; + int plen; + + /* 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(); + + /* 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)); } - opt = av[optind][1]; - if (!opt) - usage(); - if (strchr("eilcpLRo", opt)) /* options with arguments */ - { - optarg = av[optind] + 2; - if (strcmp(optarg, "") == 0) - { - if (optind >= ac - 1) + /* 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). */ + temporarily_use_uid(original_real_uid); + + /* 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); + + /* Save our own name. */ + av0 = av[0]; + + /* Initialize option structure to indicate that no values have been set. */ + initialize_options(&options); + + /* Parse command-line arguments. */ + host = NULL; + + /* If program name is not one of the standard names, use it as host name. */ + if (strchr(av0, '/')) + cp = strrchr(av0, '/') + 1; + else + cp = av0; + if (strcmp(cp, "rsh") != 0 && strcmp(cp, "ssh") != 0 && + strcmp(cp, "rlogin") != 0 && strcmp(cp, "slogin") != 0) + host = cp; + + for (optind = 1; optind < ac; optind++) { + if (av[optind][0] != '-') { + if (host) + break; + if ((cp = strchr(av[optind], '@'))) { + options.user = av[optind]; + *cp = '\0'; + host = ++cp; + } else + host = av[optind]; + continue; + } + opt = av[optind][1]; + if (!opt) + usage(); + if (strchr("eilcpLRo", opt)) { /* options with arguments */ + optarg = av[optind] + 2; + if (strcmp(optarg, "") == 0) { + if (optind >= ac - 1) + usage(); + optarg = av[++optind]; + } + } else { + if (av[optind][2]) + usage(); + optarg = NULL; + } + switch (opt) { + 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 'g': + options.gateway_ports = 1; + break; + + case 'P': + options.use_privileged_port = 0; + break; + + case 'a': + options.forward_agent = 0; + break; +#ifdef AFS + case 'k': + options.kerberos_tgt_passing = 0; + options.afs_token_passing = 0; + break; +#endif + case 'i': + if (stat(optarg, &st) < 0) { + fprintf(stderr, "Warning: Identity file %s does not exist.\n", + optarg); + break; + } + if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) + fatal("Too many identity files specified (max %d)", + SSH_MAX_IDENTITY_FILES); + options.identity_files[options.num_identity_files++] = + xstrdup(optarg); + break; + + case 't': + tty_flag = 1; + break; + + case 'v': + case 'V': + fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n", + SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR); + fprintf(stderr, "Compiled with SSL.\n"); + if (opt == 'V') + exit(0); + debug_flag = 1; + options.log_level = SYSLOG_LEVEL_DEBUG; + break; + + case 'q': + options.log_level = SYSLOG_LEVEL_QUIET; + break; + + case 'e': + if (optarg[0] == '^' && optarg[2] == 0 && + (unsigned char) optarg[1] >= 64 && (unsigned char) optarg[1] < 128) + options.escape_char = (unsigned char) optarg[1] & 31; + else if (strlen(optarg) == 1) + options.escape_char = (unsigned char) optarg[0]; + else if (strcmp(optarg, "none") == 0) + options.escape_char = -2; + else { + fprintf(stderr, "Bad escape character '%s'.\n", optarg); + exit(1); + } + break; + + case 'c': + options.cipher = cipher_number(optarg); + if (options.cipher == -1) { + fprintf(stderr, "Unknown cipher type '%s'\n", optarg); + exit(1); + } + break; + + case 'p': + options.port = atoi(optarg); + if (options.port < 1 || options.port > 65535) { + fprintf(stderr, "Bad port %s.\n", optarg); + exit(1); + } + break; + + case 'l': + options.user = optarg; + break; + + case 'R': + if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, + &fwd_host_port) != 3) { + fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); + usage(); + /* NOTREACHED */ + } + add_remote_forward(&options, fwd_port, buf, fwd_host_port); + break; + + case 'L': + if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, + &fwd_host_port) != 3) { + fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); + usage(); + /* NOTREACHED */ + } + add_local_forward(&options, fwd_port, buf, fwd_host_port); + break; + + case 'C': + options.compression = 1; + break; + + case 'o': + dummy = 1; + if (process_config_line(&options, host ? host : "", optarg, + "command-line", 0, &dummy) != 0) + exit(1); + break; + + default: + usage(); + } + } + + /* Check that we got a host name. */ + if (!host) usage(); - optarg = av[++optind]; - } + + /* check if RSA support exists */ + if (rsa_alive() == 0) { + fprintf(stderr, + "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", + __progname); + exit(1); } - else - { - if (av[optind][2]) - usage(); - optarg = NULL; + /* 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 (optind == ac) { + /* No command specified - execute shell on a tty. */ + tty_flag = 1; + } else { + /* A command has been specified. Store it into the + buffer. */ + for (i = optind; i < ac; i++) { + if (i > optind) + buffer_append(&command, " ", 1); + buffer_append(&command, av[i], strlen(av[i])); + } } - switch (opt) - { - 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 'g': - options.gateway_ports = 1; - break; - - case 'P': - options.use_privileged_port = 0; - break; - - case 'a': - options.forward_agent = 0; - break; -#ifdef AFS - case 'k': - options.kerberos_tgt_passing = 0; - options.afs_token_passing = 0; - break; -#endif - case 'i': - if (stat(optarg, &st) < 0) - { - fprintf(stderr, "Warning: Identity file %s does not exist.\n", - optarg); - break; - } - if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES) - fatal("Too many identity files specified (max %d)", - SSH_MAX_IDENTITY_FILES); - options.identity_files[options.num_identity_files++] = - xstrdup(optarg); - break; - - case 't': - tty_flag = 1; - break; - - case 'v': - case 'V': - fprintf(stderr, "SSH Version %s, protocol version %d.%d.\n", - SSH_VERSION, PROTOCOL_MAJOR, PROTOCOL_MINOR); - fprintf(stderr, "Compiled with SSL.\n"); - if (opt == 'V') - exit(0); - debug_flag = 1; - options.log_level = SYSLOG_LEVEL_DEBUG; - break; - - case 'q': - options.log_level = SYSLOG_LEVEL_QUIET; - break; - - case 'e': - if (optarg[0] == '^' && optarg[2] == 0 && - (unsigned char)optarg[1] >= 64 && (unsigned char)optarg[1] < 128) - options.escape_char = (unsigned char)optarg[1] & 31; - else - if (strlen(optarg) == 1) - options.escape_char = (unsigned char)optarg[0]; - else - if (strcmp(optarg, "none") == 0) - options.escape_char = -2; - else - { - fprintf(stderr, "Bad escape character '%s'.\n", optarg); - exit(1); + + /* Cannot fork to background if no command. */ + if (fork_after_authentication_flag && buffer_len(&command) == 0) + fatal("Cannot fork into background without a command to execute."); + + /* Allocate a tty by default if no command specified. */ + if (buffer_len(&command) == 0) + tty_flag = 1; + + /* Do not allocate a tty if stdin is not a tty. */ + if (!isatty(fileno(stdin))) { + if (tty_flag) + fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); + tty_flag = 0; + } + /* Get user data. */ + pw = getpwuid(original_real_uid); + if (!pw) { + fprintf(stderr, "You don't exist, go away!\n"); + exit(1); + } + /* 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; + + /* Initialize "log" output. Since we are the client all output + actually goes to the terminal. */ + log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); + + /* Read per-user configuration file. */ + snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); + read_config_file(buf, host, &options); + + /* Read systemwide configuration file. */ + read_config_file(HOST_CONFIG_FILE, host, &options); + + /* Fill configuration defaults. */ + fill_default_options(&options); + + /* reinit */ + log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); + + if (options.user == NULL) + options.user = xstrdup(pw->pw_name); + + if (options.hostname != NULL) + host = options.hostname; + + /* Find canonic host name. */ + if (strchr(host, '.') == 0) { + struct hostent *hp = gethostbyname(host); + if (hp != 0) { + if (strchr(hp->h_name, '.') != 0) + host = xstrdup(hp->h_name); + else if (hp->h_aliases != 0 + && hp->h_aliases[0] != 0 + && strchr(hp->h_aliases[0], '.') != 0) + host = xstrdup(hp->h_aliases[0]); } - break; - - case 'c': - options.cipher = cipher_number(optarg); - if (options.cipher == -1) - { - fprintf(stderr, "Unknown cipher type '%s'\n", optarg); - exit(1); - } - break; - - case 'p': - options.port = atoi(optarg); - if (options.port < 1 || options.port > 65535) - { - fprintf(stderr, "Bad port %s.\n", optarg); - exit(1); - } - break; - - case 'l': - options.user = optarg; - break; - - case 'R': - if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, - &fwd_host_port) != 3) - { - fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); - usage(); - /*NOTREACHED*/ - } - add_remote_forward(&options, fwd_port, buf, fwd_host_port); - break; - - case 'L': - if (sscanf(optarg, "%d:%255[^:]:%d", &fwd_port, buf, - &fwd_host_port) != 3) - { - fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg); - usage(); - /*NOTREACHED*/ - } - add_local_forward(&options, fwd_port, buf, fwd_host_port); - break; - - case 'C': - options.compression = 1; - break; - - case 'o': - dummy = 1; - if (process_config_line(&options, host ? host : "", optarg, - "command-line", 0, &dummy) != 0) - exit(1); - break; - - default: - usage(); } - } - - /* Check that we got a host name. */ - if (!host) - usage(); - - /* check if RSA support exists */ - if (rsa_alive() == 0) { - - fprintf(stderr, - "%s: no RSA support in libssl and libcrypto. See ssl(8).\n", - __progname); - exit(1); - } - - /* 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 (optind == ac) - { - /* No command specified - execute shell on a tty. */ - tty_flag = 1; - } - else - { - /* A command has been specified. Store it into the buffer. */ - for (i = optind; i < ac; i++) - { - if (i > optind) - buffer_append(&command, " ", 1); - buffer_append(&command, av[i], strlen(av[i])); + /* Disable rhosts authentication if not running as root. */ + if (original_effective_uid != 0 || !options.use_privileged_port) { + options.rhosts_authentication = 0; + options.rhosts_rsa_authentication = 0; + } + /* If using rsh has been selected, exec it now (without trying + anything else). Note that we must release privileges first. */ + if (options.use_rsh) { + /* Restore our superuser privileges. This must be done + before permanently setting the uid. */ + restore_uid(); + + /* Switch to the original uid permanently. */ + permanently_set_uid(original_real_uid); + + /* Execute rsh. */ + rsh_connect(host, options.user, &command); + fatal("rsh_connect returned"); } - } - - /* Cannot fork to background if no command. */ - if (fork_after_authentication_flag && buffer_len(&command) == 0) - fatal("Cannot fork into background without a command to execute."); - - /* Allocate a tty by default if no command specified. */ - if (buffer_len(&command) == 0) - tty_flag = 1; - - /* Do not allocate a tty if stdin is not a tty. */ - if (!isatty(fileno(stdin))) - { - if (tty_flag) - fprintf(stderr, "Pseudo-terminal will not be allocated because stdin is not a terminal.\n"); - tty_flag = 0; - } - - /* Get user data. */ - pw = getpwuid(original_real_uid); - if (!pw) - { - fprintf(stderr, "You don't exist, go away!\n"); - exit(1); - } - - /* 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; - - /* Initialize "log" output. Since we are the client all output actually - goes to the terminal. */ - log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); - - /* Read per-user configuration file. */ - snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_CONFFILE); - read_config_file(buf, host, &options); - - /* Read systemwide configuration file. */ - read_config_file(HOST_CONFIG_FILE, host, &options); - - /* Fill configuration defaults. */ - fill_default_options(&options); - - /* reinit */ - log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0); - - if (options.user == NULL) - options.user = xstrdup(pw->pw_name); - - if (options.hostname != NULL) - host = options.hostname; - - /* Find canonic host name. */ - if (strchr(host, '.') == 0) - { - struct hostent *hp = gethostbyname(host); - if (hp != 0) - { - if (strchr(hp->h_name, '.') != 0) - host = xstrdup(hp->h_name); - else if (hp->h_aliases != 0 - && hp->h_aliases[0] != 0 - && strchr(hp->h_aliases[0], '.') != 0) - host = xstrdup(hp->h_aliases[0]); + /* Restore our superuser privileges. */ + restore_uid(); + + /* Open a connection to the remote host. This needs root + privileges if rhosts_{rsa_}authentication is enabled. */ + + ok = ssh_connect(host, &hostaddr, options.port, + options.connection_attempts, + !options.rhosts_authentication && + !options.rhosts_rsa_authentication, + original_real_uid, + options.proxy_command); + + /* 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 (ok) { + host_private_key = RSA_new(); + if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL)) + host_private_key_loaded = 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. */ + + /* Note that some legacy systems need to postpone the following + call to permanently_set_uid() until the private hostkey is + destroyed with RSA_free(). Otherwise the calling user could + ptrace() the process, read the private hostkey and impersonate + the host. OpenBSD does not allow ptracing of setuid processes. */ + + permanently_set_uid(original_real_uid); + + /* Now that we are back to our own permissions, create ~/.ssh + directory if it doesn\'t already exist. */ + snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); + if (stat(buf, &st) < 0) + if (mkdir(buf, 0755) < 0) + error("Could not create directory '%.200s'.", buf); + + /* Check if the connection failed, and try "rsh" if appropriate. */ + if (!ok) { + if (options.port != 0) + log("Secure connection to %.100s on port %d refused%.100s.", + host, options.port, + options.fallback_to_rsh ? "; reverting to insecure method" : ""); + else + log("Secure connection to %.100s refused%.100s.", host, + options.fallback_to_rsh ? "; reverting to insecure method" : ""); + + if (options.fallback_to_rsh) { + rsh_connect(host, options.user, &command); + fatal("rsh_connect returned"); + } + exit(1); } - } - - /* Disable rhosts authentication if not running as root. */ - if (original_effective_uid != 0 || !options.use_privileged_port) - { - options.rhosts_authentication = 0; - options.rhosts_rsa_authentication = 0; - } - - /* If using rsh has been selected, exec it now (without trying anything - else). Note that we must release privileges first. */ - if (options.use_rsh) - { - /* Restore our superuser privileges. This must be done before - permanently setting the uid. */ - restore_uid(); - - /* Switch to the original uid permanently. */ - permanently_set_uid(original_real_uid); - - /* Execute rsh. */ - rsh_connect(host, options.user, &command); - fatal("rsh_connect returned"); - } - - /* Restore our superuser privileges. */ - restore_uid(); - - /* Open a connection to the remote host. This needs root privileges if - rhosts_{rsa_}authentication is enabled. */ - - ok = ssh_connect(host, &hostaddr, options.port, options.connection_attempts, - !options.rhosts_authentication && - !options.rhosts_rsa_authentication, - original_real_uid, options.proxy_command); - - /* 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 (ok) - { - host_private_key = RSA_new(); - if (load_private_key(HOST_KEY_FILE, "", host_private_key, NULL)) - host_private_key_loaded = 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. */ - - /* Note that some legacy systems need to postpone the following call to - permanently_set_uid() until the private hostkey is destroyed with - RSA_free(). Otherwise the calling user could ptrace() the process, - read the private hostkey and impersonate the host. OpenBSD does not - allow ptracing of setuid processes. */ - - permanently_set_uid(original_real_uid); - - /* Now that we are back to our own permissions, create ~/.ssh directory - if it doesn\'t already exist. */ - snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, SSH_USER_DIR); - if (stat(buf, &st) < 0) - if (mkdir(buf, 0755) < 0) - error("Could not create directory '%.200s'.", buf); - - /* Check if the connection failed, and try "rsh" if appropriate. */ - if (!ok) - { - if (options.port != 0) - log("Secure connection to %.100s on port %d refused%.100s.", - host, options.port, - options.fallback_to_rsh ? "; reverting to insecure method" : ""); - else - log("Secure connection to %.100s refused%.100s.", host, - options.fallback_to_rsh ? "; reverting to insecure method" : ""); - - if (options.fallback_to_rsh) - { - rsh_connect(host, options.user, &command); - fatal("rsh_connect returned"); + /* Expand ~ in options.identity_files. */ + for (i = 0; i < options.num_identity_files; i++) + options.identity_files[i] = + tilde_expand_filename(options.identity_files[i], original_real_uid); + + /* Expand ~ in known host file names. */ + options.system_hostfile = tilde_expand_filename(options.system_hostfile, + original_real_uid); + options.user_hostfile = tilde_expand_filename(options.user_hostfile, + original_real_uid); + + /* Log into the remote system. This never returns if the login fails. */ + ssh_login(host_private_key_loaded, host_private_key, + host, &hostaddr, original_real_uid); + + /* We no longer need the host private key. Clear it now. */ + if (host_private_key_loaded) + RSA_free(host_private_key); /* Destroys contents safely */ + + /* Close connection cleanly after attack. */ + cipher_attack_detected = packet_disconnect; + + /* If requested, fork and let ssh continue in the background. */ + if (fork_after_authentication_flag) { + int ret = fork(); + if (ret == -1) + fatal("fork failed: %.100s", strerror(errno)); + if (ret != 0) + exit(0); + setsid(); } - exit(1); - } - - /* Expand ~ in options.identity_files. */ - for (i = 0; i < options.num_identity_files; i++) - options.identity_files[i] = - tilde_expand_filename(options.identity_files[i], original_real_uid); - - /* Expand ~ in known host file names. */ - options.system_hostfile = tilde_expand_filename(options.system_hostfile, - original_real_uid); - options.user_hostfile = tilde_expand_filename(options.user_hostfile, - original_real_uid); - - /* Log into the remote system. This never returns if the login fails. */ - ssh_login(host_private_key_loaded, host_private_key, - host, &hostaddr, original_real_uid); - - /* We no longer need the host private key. Clear it now. */ - if (host_private_key_loaded) - RSA_free(host_private_key); /* Destroys contents safely */ - - /* Close connection cleanly after attack. */ - cipher_attack_detected = packet_disconnect; - - /* Enable compression if requested. */ - i |