/* * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * * As far as I am concerned, the code I have written for this software * can be used freely for any purpose. Any derived versions of this * software must be clearly marked as such, and if the derived work is * incompatible with the protocol description in the RFC file, it must be * called by a name other than "ssh" or "Secure Shell". * * SSH2 support by Markus Friedl. * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" RCSID("$OpenBSD: session.c,v 1.156 2003/05/11 20:30:25 markus Exp $"); #include "ssh.h" #include "ssh1.h" #include "ssh2.h" #include "xmalloc.h" #include "sshpty.h" #include "packet.h" #include "buffer.h" #include "mpaux.h" #include "uidswap.h" #include "compat.h" #include "channels.h" #include "bufaux.h" #include "auth.h" #include "auth-options.h" #include "pathnames.h" #include "log.h" #include "servconf.h" #include "sshlogin.h" #include "serverloop.h" #include "canohost.h" #include "session.h" #include "monitor_wrap.h" /* func */ Session *session_new(void); void session_set_fds(Session *, int, int, int); void session_pty_cleanup(void *); void session_proctitle(Session *); int session_setup_x11fwd(Session *); void do_exec_pty(Session *, const char *); void do_exec_no_pty(Session *, const char *); void do_exec(Session *, const char *); void do_login(Session *, const char *); void do_child(Session *, const char *); void do_motd(void); int check_quietlogin(Session *, const char *); static void do_authenticated1(Authctxt *); static void do_authenticated2(Authctxt *); static int session_pty_req(Session *); /* import */ extern ServerOptions options; extern char *__progname; extern int log_stderr; extern int debug_flag; extern u_int utmp_len; extern int startup_pipe; extern void destroy_sensitive_data(void); /* original command from peer. */ const char *original_command = NULL; /* data */ #define MAX_SESSIONS 10 Session sessions[MAX_SESSIONS]; #ifdef HAVE_LOGIN_CAP login_cap_t *lc; #endif /* Name and directory of socket for authentication agent forwarding. */ static char *auth_sock_name = NULL; static char *auth_sock_dir = NULL; /* removes the agent forwarding socket */ static void auth_sock_cleanup_proc(void *_pw) { struct passwd *pw = _pw; if (auth_sock_name != NULL) { temporarily_use_uid(pw); unlink(auth_sock_name); rmdir(auth_sock_dir); auth_sock_name = NULL; restore_uid(); } } static int auth_input_request_forwarding(struct passwd * pw) { Channel *nc; int sock; struct sockaddr_un sunaddr; if (auth_sock_name != NULL) { error("authentication forwarding requested twice."); return 0; } /* Temporarily drop privileged uid for mkdir/bind. */ temporarily_use_uid(pw); /* Allocate a buffer for the socket name, and format the name. */ auth_sock_name = xmalloc(MAXPATHLEN); auth_sock_dir = xmalloc(MAXPATHLEN); strlcpy(auth_sock_dir, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); /* Create private directory for socket */ if (mkdtemp(auth_sock_dir) == NULL) { packet_send_debug("Agent forwarding disabled: " "mkdtemp() failed: %.100s", strerror(errno)); restore_uid(); xfree(auth_sock_name); xfree(auth_sock_dir); auth_sock_name = NULL; auth_sock_dir = NULL; return 0; } snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld", auth_sock_dir, (long) getpid()); /* delete agent socket on fatal() */ fatal_add_cleanup(auth_sock_cleanup_proc, pw); /* Create the socket. */ sock = socket(AF_UNIX, SOCK_STREAM, 0); if (sock < 0) packet_disconnect("socket: %.100s", strerror(errno)); /* Bind it to the name. */ memset(&sunaddr, 0, sizeof(sunaddr)); sunaddr.sun_family = AF_UNIX; strlcpy(sunaddr.sun_path, auth_sock_name, sizeof(sunaddr.sun_path)); if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) packet_disconnect("bind: %.100s", strerror(errno)); /* Restore the privileged uid. */ restore_uid(); /* Start listening on the socket. */ if (listen(sock, 5) < 0) packet_disconnect("listen: %.100s", strerror(errno)); /* Allocate a channel for the authentication agent socket. */ nc = channel_new("auth socket", SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "auth socket", 1); strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); return 1; } void do_authenticated(Authctxt *authctxt) { setproctitle("%s", authctxt->pw->pw_name); /* * Cancel the alarm we set to limit the time taken for * authentication. */ alarm(0); if (startup_pipe != -1) { close(startup_pipe); startup_pipe = -1; } /* setup the channel layer */ if (!no_port_forwarding_flag && options.allow_tcp_forwarding) channel_permit_all_opens(); if (compat20) do_authenticated2(authctxt); else do_authenticated1(authctxt); /* remove agent socket */ if (auth_sock_name != NULL) auth_sock_cleanup_proc(authctxt->pw); #ifdef KRB4 if (options.kerberos_ticket_cleanup) krb4_cleanup_proc(authctxt); #endif #ifdef KRB5 if (options.kerberos_ticket_cleanup) krb5_cleanup_proc(authctxt); #endif } /* * 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. */ static void do_authenticated1(Authctxt *authctxt) { Session *s; char *command; int success, type, screen_flag; int enable_compression_after_reply = 0; u_int proto_len, data_len, dlen, compression_level = 0; s = session_new(); s->authctxt = authctxt; s->pw = authctxt->pw; /* * We stay in this loop until the client requests to execute a shell * or a command. */ for (;;) { success = 0; /* Get a packet from the client. */ type = packet_read(); /* Process the packet. */ switch (type) { case SSH_CMSG_REQUEST_COMPRESSION: compression_level = packet_get_int(); packet_check_eom(); if (compression_level < 1 || compression_level > 9) { packet_send_debug("Received illegal compression level %d.", compression_level); break; } if (!options.compression) { debug2("compression disabled"); break; } /* Enable compression after we have responded with SUCCESS. */ enable_compression_after_reply = 1; success = 1; break; case SSH_CMSG_REQUEST_PTY: success = session_pty_req(s); break; case SSH_CMSG_X11_REQUEST_FORWARDING: s->auth_proto = packet_get_string(&proto_len); s->auth_data = packet_get_string(&data_len); screen_flag = packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER; debug2("SSH_PROTOFLAG_SCREEN_NUMBER: %d", screen_flag); if (packet_remaining() == 4) { if (!screen_flag) debug2("Buggy client: " "X11 screen flag missing"); s->screen = packet_get_int(); } else { s->screen = 0; } packet_check_eom(); success = session_setup_x11fwd(s); if (!success) { xfree(s->auth_proto); xfree(s->auth_data); s->auth_proto = NULL; s->auth_data = NULL; } break; case SSH_CMSG_AGENT_REQUEST_FORWARDING: if (no_agent_forwarding_flag || compat13) { debug("Authentication agent forwarding not permitted for this authentication."); break; } debug("Received authentication agent forwarding request."); success = auth_input_request_forwarding(s->pw); break; case SSH_CMSG_PORT_FORWARD_REQUEST: if (no_port_forwarding_flag) { debug("Port forwarding not permitted for this authentication."); break; } if (!options.allow_tcp_forwarding) { debug("Port forwarding not permitted."); break; } debug("Received TCP/IP port forwarding request."); channel_input_port_forward_request(s->pw->pw_uid == 0, options.gateway_ports); success = 1; break; case SSH_CMSG_MAX_PACKET_SIZE: if (packet_set_maxsize(packet_get_int()) > 0) success = 1; break; #if defined(AFS) || defined(KRB5) case SSH_CMSG_HAVE_KERBEROS_TGT: if (!options.kerberos_tgt_passing) { verbose("Kerberos TGT passing disabled."); } else { char *kdata = packet_get_string(&dlen); packet_check_eom(); /* XXX - 0x41, see creds_to_radix version */ if (kdata[0] != 0x41) { #ifdef KRB5 krb5_data tgt; tgt.data = kdata; tgt.length = dlen; if (auth_krb5_tgt(s->authctxt, &tgt)) success = 1; else verbose("Kerberos v5 TGT refused for %.100s", s->authctxt->user); #endif /* KRB5 */ } else { #ifdef AFS if (auth_krb4_tgt(s->authctxt, kdata)) success = 1; else verbose("Kerberos v4 TGT refused for %.100s", s->authctxt->user); #endif /* AFS */ } xfree(kdata); } break; #endif /* AFS || KRB5 */ #ifdef AFS case SSH_CMSG_HAVE_AFS_TOKEN: if (!options.afs_token_passing || !k_hasafs()) { verbose("AFS token passing disabled."); } else { /* Accept AFS token. */ char *token = packet_get_string(&dlen); packet_check_eom(); if (auth_afs_token(s->authctxt, token)) success = 1; else verbose("AFS token refused for %.100s", s->authctxt->user); xfree(token); } break; #endif /* AFS */ case SSH_CMSG_EXEC_SHELL: case SSH_CMSG_EXEC_CMD: if (type == SSH_CMSG_EXEC_CMD) { command = packet_get_string(&dlen); debug("Exec command '%.500s'", command); do_exec(s, command); xfree(command); } else { do_exec(s, NULL); } packet_check_eom(); session_close(s); return; default: /* * Any unknown messages in this phase are ignored, * and a failure message is returned. */ logit("Unknown packet type received after authentication: %d", type); } packet_start(success ? SSH_SMSG_SUCCESS : SSH_SMSG_FAILURE); 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); } } } /* * 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(Session *s, const char *command) { pid_t 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 */ if (s == NULL) fatal("do_exec_no_pty: no session"); session_proctitle(s); /* Fork the child. */ if ((pid = fork()) == 0) { fatal_remove_all_cleanups(); /* Child. Reinitialize the log since the pid has changed. */ log_init(__progname, 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(s, command); /* NOTREACHED */ } if (pid < 0) packet_disconnect("fork failed: %.100s", strerror(errno)); s->pid = pid; /* Set interactive/non-interactive mode. */ packet_set_interactive(s->display != NULL); #ifdef USE_PIPES /* We are the parent. Close the child sides of the pipes. */ close(pin[0]); close(pout[1]); close(perr[1]); if (compat20) { session_set_fds(s, pin[1], pout[0], s->is_subsystem ? -1 : perr[0]); } else { /* Enter the interactive session. */ server_loop(pid, pin[1], pout[0], perr[0]); /* server_loop has closed pin[1], pout[0], and perr[0]. */ } #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. */ if (compat20) { session_set_fds(s, inout[1], inout[1], s->is_subsystem ? -1 : err[1]); } else { server_loop(pid, inout[1], inout[1], err[1]); /* server_loop has closed inout[1] and err[1]. */ } #endif /* USE_PIPES */ } /* * 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(Session *s, const char *command) { int fdout, ptyfd, ttyfd, ptymaster; pid_t pid; if (s == NULL) fatal("do_exec_pty: no session"); ptyfd = s->ptyfd; ttyfd = s->ttyfd; /* Fork the child. */ if ((pid = fork()) == 0) { fatal_remove_all_cleanups(); /* Child. Reinitialize the log because the pid has changed. */ log_init(__progname, 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, s->tty); /* Redirect stdin/stdout/stderr from the pseudo tty. */ if (dup2(ttyfd, 0) < 0) error("dup2 stdin: %s", strerror(errno)); if (dup2(ttyfd, 1) < 0) error("dup2 stdout: %s", strerror(errno)); if (dup2(ttyfd, 2) < 0) error("dup2 stderr: %s", strerror(errno)); /* Close the extra descriptor for the pseudo tty. */ close(ttyfd); /* record login, etc. similar to login(1) */ if (!(options.use_login && command == NULL)) do_login(s, command); /* Do common processing for the child, such as execing the command. */ do_child(s, command); /* NOTREACHED */ } if (pid < 0) packet_disconnect("fork failed: %.100s", strerror(errno)); s->pid = pid; /* 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 #1 failed: %.100s", strerror(errno)); /* we keep a reference to the pty master */ ptymaster = dup(ptyfd); if (ptymaster < 0) packet_disconnect("dup #2 failed: %.100s", strerror(errno)); s->ptymaster = ptymaster; /* Enter interactive session. */ packet_set_interactive(1); if (compat20) { session_set_fds(s, ptyfd, fdout, -1); } else { server_loop(pid, ptyfd, fdout, -1); /* server_loop _has_ closed ptyfd and fdout. */ } } /* * This is called to fork and execute a command. If another command is * to be forced, execute that instead. */ void do_exec(Session *s, const char *command) { if (forced_command) { original_command = command; command = forced_command; debug("Forced command '%.900s'", command); } if (s->ttyfd != -1) do_exec_pty(s, command); else do_exec_no_pty(s, command); original_command = NULL; } /* administrative, login(1)-like work */ void do_login(Session *s, const char *command) { char *time_string; socklen_t fromlen; struct sockaddr_storage from; struct passwd * pw = s->pw; pid_t pid = getpid(); /* * Get IP address of client. If the connection is not a socket, let * the address be 0.0.0.0. */ memset(&from, 0, sizeof(from)); fromlen = sizeof(from); if (packet_connection_is_on_socket()) { 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 tty from the remote host. */ if (!use_privsep) record_login(pid, s->tty, pw->pw_name, pw->pw_uid, get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping), (struct sockaddr *)&from, fromlen); if (check_quietlogin(s, command)) return; if (options.print_lastlog && s->last_login_time != 0) { time_string = ctime(&s->last_login_time); if (strchr(time_string, '\n')) *strchr(time_string, '\n') = 0; if (strcmp(s->hostname, "") == 0) printf("Last login: %s\r\n", time_string); else printf("Last login: %s from %s\r\n", time_string, s->hostname); } do_motd(); } /* * Display the message of the day. */ void do_motd(void) { FILE *f; char buf[256]; if (options.print_motd) { #ifdef HAVE_LOGIN_CAP f = fopen(login_getcapstr(lc, "welcome", "/etc/motd", "/etc/motd"), "r"); #else f = fopen("/etc/motd", "r"); #endif if (f) { while (fgets(buf, sizeof(buf), f)) fputs(buf, stdout); fclose(f); } } } /* * Check for quiet login, either .hushlogin or command given. */ int check_quietlogin(Session *s, const char *command) { char buf[256]; struct passwd *pw = s->pw; struct stat st; /* Return 1 if .hushlogin exists or a command given. */ if (command != NULL) return 1; snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); #ifdef HAVE_LOGIN_CAP if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) return 1; #else if (stat(buf, &st) >= 0) return 1; #endif return 0; } /* * Sets the value of the given variable in the environment. If the variable * already exists, its value is overriden. */ static void child_set_env(char ***envp, u_int *envsizep, const char *name, const char *value) { u_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) { if (*envsizep >= 1000) fatal("child_set_env: too many env vars," " skipping: %.100s", name); (*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. */ static void read_environment_file(char ***env, u_int *envsize, const char *filename) { FILE *f; char buf[4096]; char *cp, *value; u_int lineno = 0; f = fopen(filename, "r"); if (!f) return; while (fgets(buf, sizeof(buf), f)) { if (++lineno > 1000) fatal("Too many lines in environment file %s", filename); 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 %u in %.100s\n", lineno, filename); 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); } static char ** do_setup_env(Session *s, const char *shell) { char buf[256]; u_int i, envsize; char **env, *laddr; struct passwd *pw = s->pw; /* 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); #ifdef HAVE_LOGIN_CAP if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH) < 0) child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); else child_set_env(&env, &envsize, "PATH", getenv("PATH")); #else child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); #endif 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. */ if (!options.use_login) { while (custom_environment) { struct envstring *ce = custom_environment; char *str = ce->s; for (i = 0; str[i] != '=' && str[i]; i++) ; if (str[i] == '=') { str[i] = 0; child_set_env(&env, &envsize, str, str + i + 1); } custom_environment = ce->next; xfree(ce->s); xfree(ce); } } /* SSH_CLIENT deprecated */ snprintf(buf, sizeof buf, "%.50s %d %d", get_remote_ipaddr(), get_remote_port(), get_local_port()); child_set_env(&env, &envsize, "SSH_CLIENT", buf); laddr = get_local_ipaddr(packet_get_connection_in()); snprintf(buf, sizeof buf, "%.50s %d %.50s %d", get_remote_ipaddr(), get_remote_port(), laddr, get_local_port()); xfree(laddr); child_set_env(&env, &envsize, "SSH_CONNECTION", buf); if (s->ttyfd != -1) child_set_env(&env, &envsize, "SSH_TTY", s->tty); if (s->term) child_set_env(&env, &envsize, "TERM", s->term); if (s->display) child_set_env(&env, &envsize, "DISPLAY", s->display); if (original_command) child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", original_command); #ifdef KRB4 if (s->authctxt->krb4_ticket_file) child_set_env(&env, &envsize, "KRBTKFILE", s->authctxt->krb4_ticket_file); #endif #ifdef KRB5 if (s->authctxt->krb5_ticket_file) child_set_env(&env, &envsize, "KRB5CCNAME", s->authctxt->krb5_ticket_file); #endif if (auth_sock_name != NULL) child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME, auth_sock_name); /* read $HOME/.ssh/environment. */ if (options.permit_user_env && !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]); } return env; } /* * Run $HOME/.ssh/rc, /etc/ssh/sshrc, or xauth (whichever is found * first in this order). */ static void do_rc_files(Session *s, const char *shell) { FILE *f = NULL; char cmd[1024]; int do_xauth; struct stat st; do_xauth = s->display != NULL && s->auth_proto != NULL && s->auth_data != NULL; /* ignore _PATH_SSH_USER_RC for subsystems */ if (!s->is_subsystem && (stat(_PATH_SSH_USER_RC, &st) >= 0)) { snprintf(cmd, sizeof cmd, "%s -c '%s %s'", shell, _PATH_BSHELL, _PATH_SSH_USER_RC); if (debug_flag) fprintf(stderr, "Running %s\n", cmd); f = popen(cmd, "w"); if (f) { if (do_xauth) fprintf(f, "%s %s\n", s->auth_proto, s->auth_data); pclose(f); } else fprintf(stderr, "Could not run %s\n", _PATH_SSH_USER_RC); } else if (stat(_PATH_SSH_SYSTEM_RC, &st) >= 0) { if (debug_flag) fprintf(stderr, "Running %s %s\n", _PATH_BSHELL, _PATH_SSH_SYSTEM_RC); f = popen(_PATH_BSHELL " " _PATH_SSH_SYSTEM_RC, "w"); if (f) { if (do_xauth) fprintf(f, "%s %s\n", s->auth_proto, s->auth_data); pclose(f); } else fprintf(stderr, "Could not run %s\n", _PATH_SSH_SYSTEM_RC); } else if (do_xauth && options.xauth_location != NULL) { /* Add authority data to .Xauthority if appropriate. */ if (debug_flag) { fprintf(stderr, "Running %.500s remove %.100s\n", options.xauth_location, s->auth_display); fprintf(stderr, "%.500s add %.100s %.100s %.100s\n", options.xauth_location, s->auth_display, s->auth_proto, s->auth_data); } snprintf(cmd, sizeof cmd, "%s -q -", options.xauth_location); f = popen(cmd, "w"); if (f) { fprintf(f, "remove %s\n", s->auth_display); fprintf(f, "add %s %s %s\n", s->auth_display, s->auth_proto, s->auth_data); pclose(f); } else { fprintf(stderr, "Could not run %s\n", cmd); } } } static void do_nologin(struct passwd *pw) { FILE *f = NULL; char buf[1024]; #ifdef HAVE_LOGIN_CAP if (!login_getcapbool(lc, "ignorenologin", 0) && pw->pw_uid) f = fopen(login_getcapstr(lc, "nologin", _PATH_NOLOGIN, _PATH_NOLOGIN), "r"); #else if (pw->pw_uid) f = fopen(_PATH_NOLOGIN, "r"); #endif if (f) { /* /etc/nologin exists. Print its contents and exit. */ logit("User %.100s not allowed because %s exists", pw->pw_name, _PATH_NOLOGIN); while (fgets(buf, sizeof(buf), f)) fputs(buf, stderr); fclose(f); exit(254); } } /* Set login name, uid, gid, and groups. */ void do_setusercontext(struct passwd *pw) { if (getuid() == 0 || geteuid() == 0) { #ifdef HAVE_LOGIN_CAP if (setusercontext(lc, pw, pw->pw_uid, (LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) { perror("unable to set user context"); exit(1); } #else if (setlogin(pw->pw_name) < 0) error("setlogin failed: %s", strerror(errno)); 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); #endif } if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) fatal("Failed to set uids to %u.", (u_int) pw->pw_uid); } static void launch_login(struct passwd *pw, const char *hostname) { /* Launch login(1). */ execl("/usr/bin/login", "login", "-h", hostname, "-p", "-f", "--", pw->pw_name, (char *)NULL); /* Login couldn't be executed, die. */ perror("login"); exit(1); } /* * 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(Session *s, const char *command) { extern char **environ; char **env; char *argv[10]; const char *shell, *shell0, *hostname = NULL; struct passwd *pw = s->pw; u_int i; /* remove hostkey from the child's memory */ destroy_sensitive_data(); /* login(1) is only called if we execute the login shell */ if (options.use_login && command != NULL) options.use_login = 0; /* * 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) { do_nologin(pw); do_setusercontext(pw); } /* * 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; /* * Make sure $SHELL points to the shell from the password file, * even if shell is overridden from login.conf */ env = do_setup_env(s, shell); #ifdef HAVE_LOGIN_CAP shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); #endif /* we have to stash the hostname before we close our socket. */ if (options.use_login) hostname = get_remote_name_or_ip(utmp_len, options.verify_reverse_mapping); /* * 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); /* * Must take new environment into use so that .ssh/rc, * /etc/ssh/sshrc and xauth are run in the proper environment. */ environ = env; #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 */ /* 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)); #ifdef HAVE_LOGIN_CAP if (login_getcapbool(lc, "requirehome", 0)) exit(1); #endif } if (!options.use_login) do_rc_files(s, shell); /* restore SIGPIPE for child */ signal(SIGPIPE, SIG_DFL); if (options.use_login) { launch_login(pw, hostname); /* NEVERREACHED */ } /* Get the last component of the shell name. */ if ((shell0 = strrchr(shell, '/')) != NULL) shell0++; else shell0 = 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) { char argv0[256]; /* Start the shell. Set initial character to '-'. */ argv0[0] = '-'; if (strlcpy(argv0 + 1, shell0, sizeof(argv0) - 1) >= sizeof(argv0) - 1) { errno = EINVAL; perror(shell); exit(1); } /* Execute the shell. */ argv[0] = argv0; argv[1] = NULL; execve(shell, argv, env); /* Executing the shell failed. */ perror(shell); exit(1); } /* * Execute the command using the user's shell. This uses the -c * option to execute the command. */ argv[0] = (char *) shell0; argv[1] = "-c"; argv[2] = (char *) command; argv[3] = NULL; execve(shell, argv, env); perror(shell); exit(1); } Session * session_new(void) { int i; static int did_init = 0; if (!did_init) { debug("session_new: init"); for (i = 0; i < MAX_SESSIONS; i++) { sessions[i].used = 0; } did_init = 1; } for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (! s->used) { memset(s, 0, sizeof(*s)); s->chanid = -1; s->ptyfd = -1; s->ttyfd = -1; s->used = 1; s->self = i; debug("session_new: session %d", i); return s; } } return NULL; } static void session_dump(void) { int i; for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; debug("dump: used %d session %d %p channel %d pid %ld", s->used, s->self, s, s->chanid, (long)s->pid); } } int session_open(Authctxt *authctxt, int chanid) { Session *s = session_new(); debug("session_open: channel %d", chanid); if (s == NULL) { error("no more sessions"); return 0; } s->authctxt = authctxt; s->pw = authctxt->pw; if (s->pw == NULL) fatal("no user for session %d", s->self); debug("session_open: session %d: link with channel %d", s->self, chanid); s->chanid = chanid; return 1; } Session * session_by_tty(char *tty) { int i; for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (s->used && s->ttyfd != -1 && strcmp(s->tty, tty) == 0) { debug("session_by_tty: session %d tty %s", i, tty); return s; } } debug("session_by_tty: unknown tty %.100s", tty); session_dump(); return NULL; } static Session * session_by_channel(int id) { int i; for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (s->used && s->chanid == id) { debug("session_by_channel: session %d channel %d", i, id); return s; } } debug("session_by_channel: unknown channel %d", id); session_dump(); return NULL; } static Session * session_by_pid(pid_t pid) { int i; debug("session_by_pid: pid %ld", (long)pid); for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (s->used && s->pid == pid) return s; } error("session_by_pid: unknown pid %ld", (long)pid); session_dump(); return NULL; } static int session_window_change_req(Session *s) { s->col = packet_get_int(); s->row = packet_get_int(); s->xpixel = packet_get_int(); s->ypixel = packet_get_int(); packet_check_eom(); pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); return 1; } static int session_pty_req(Session *s) { u_int len; int n_bytes; if (no_pty_flag) { debug("Allocating a pty not permitted for this authentication."); return 0; } if (s->ttyfd != -1) { packet_disconnect("Protocol error: you already have a pty."); return 0; } /* Get the time and hostname when the user last logged in. */ if (options.print_lastlog) { s->hostname[0] = '\0'; s->last_login_time = get_last_login_time(s->pw->pw_uid, s->pw->pw_name, s->hostname, sizeof(s->hostname)); } s->term = packet_get_string(&len); if (compat20) { s->col = packet_get_int(); s->row = packet_get_int(); } else { s->row = packet_get_int(); s->col = packet_get_int(); } s->xpixel = packet_get_int(); s->ypixel = packet_get_int(); if (strcmp(s->term, "") == 0) { xfree(s->term); s->term = NULL; } /* Allocate a pty and open it. */ debug("Allocating pty."); if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) { if (s->term) xfree(s->term); s->term = NULL; s->ptyfd = -1; s->ttyfd = -1; error("session_pty_req: session %d alloc failed", s->self); return 0; } debug("session_pty_req: session %d alloc %s", s->self, s->tty); /* for SSH1 the tty modes length is not given */ if (!compat20) n_bytes = packet_remaining(); tty_parse_modes(s->ttyfd, &n_bytes); /* * Add a cleanup function to clear the utmp entry and record logout * time in case we call fatal() (e.g., the connection gets closed). */ fatal_add_cleanup(session_pty_cleanup, (void *)s); if (!use_privsep) pty_setowner(s->pw, s->tty); /* Set window size from the packet. */ pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); packet_check_eom(); session_proctitle(s); return 1; } static int session_subsystem_req(Session *s) { struct stat st; u_int len; int success = 0; char *cmd, *subsys = packet_get_string(&len); int i; packet_check_eom(); logit("subsystem request for %.100s", subsys); for (i = 0; i < options.num_subsystems; i++) { if (strcmp(subsys, options.subsystem_name[i]) == 0) { cmd = options.subsystem_command[i]; if (stat(cmd, &st) < 0) { error("subsystem: cannot stat %s: %s", cmd, strerror(errno)); break; } debug("subsystem: exec() %s", cmd); s->is_subsystem = 1; do_exec(s, cmd); success = 1; break; } } if (!success) logit("subsystem request for %.100s failed, subsystem not found", subsys); xfree(subsys); return success; } static int session_x11_req(Session *s) { int success; s->single_connection = packet_get_char(); s->auth_proto = packet_get_string(NULL); s->auth_data = packet_get_string(NULL); s->screen = packet_get_int(); packet_check_eom(); success = session_setup_x11fwd(s); if (!success) { xfree(s->auth_proto); xfree(s->auth_data); s->auth_proto = NULL; s->auth_data = NULL; } return success; } static int session_shell_req(Session *s) { packet_check_eom(); do_exec(s, NULL); return 1; } static int session_exec_req(Session *s) { u_int len; char *command = packet_get_string(&len); packet_check_eom(); do_exec(s, command); xfree(command); return 1; } static int session_auth_agent_req(Session *s) { static int called = 0; packet_check_eom(); if (no_agent_forwarding_flag) { debug("session_auth_agent_req: no_agent_forwarding_flag"); return 0; } if (called) { return 0; } else { called = 1; return auth_input_request_forwarding(s->pw); } } int session_input_channel_req(Channel *c, const char *rtype) { int success = 0; Session *s; if ((s = session_by_channel(c->self)) == NULL) { logit("session_input_channel_req: no session %d req %.100s", c->self, rtype); return 0; } debug("session_input_channel_req: session %d req %s", s->self, rtype); /* * a session is in LARVAL state until a shell, a command * or a subsystem is executed */ if (c->type == SSH_CHANNEL_LARVAL) { if (strcmp(rtype, "shell") == 0) { success = session_shell_req(s); } else if (strcmp(rtype, "exec") == 0) { success = session_exec_req(s); } else if (strcmp(rtype, "pty-req") == 0) { success = session_pty_req(s); } else if (strcmp(rtype, "x11-req") == 0) { success = session_x11_req(s); } else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) { success = session_auth_agent_req(s); } else if (strcmp(rtype, "subsystem") == 0) { success = session_subsystem_req(s); } } if (strcmp(rtype, "window-change") == 0) { success = session_window_change_req(s); } return success; } void session_set_fds(Session *s, int fdin, int fdout, int fderr) { if (!compat20) fatal("session_set_fds: called for proto != 2.0"); /* * now that have a child and a pipe to the child, * we can activate our channel and register the fd's */ if (s->chanid == -1) fatal("no channel for session %d", s->self); channel_set_fds(s->chanid, fdout, fdin, fderr, fderr == -1 ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ, 1, CHAN_SES_WINDOW_DEFAULT); } /* * Function to perform pty cleanup. Also called if we get aborted abnormally * (e.g., due to a dropped connection). */ void session_pty_cleanup2(void *session) { Session *s = session; if (s == NULL) { error("session_pty_cleanup: no session"); return; } if (s->ttyfd == -1) return; debug("session_pty_cleanup: session %d release %s", s->self, s->tty); /* Record that the user has logged out. */ if (s->pid != 0) record_logout(s->pid, s->tty); /* Release the pseudo-tty. */ if (getuid() == 0) pty_release(s->tty); /* * 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. */ if (close(s->ptymaster) < 0) error("close(s->ptymaster/%d): %s", s->ptymaster, strerror(errno)); /* unlink pty from session */ s->ttyfd = -1; } void session_pty_cleanup(void *session) { PRIVSEP(session_pty_cleanup2(session)); } static char * sig2name(int sig) { #define SSH_SIG(x) if (sig == SIG ## x) return #x SSH_SIG(ABRT); SSH_SIG(ALRM); SSH_SIG(FPE); SSH_SIG(HUP); SSH_SIG(ILL); SSH_SIG(INT); SSH_SIG(KILL); SSH_SIG(PIPE); SSH_SIG(QUIT); SSH_SIG(SEGV); SSH_SIG(TERM); SSH_SIG(USR1); SSH_SIG(USR2); #undef SSH_SIG return "SIG@openssh.com"; } static void session_exit_message(Session *s, int status) { Channel *c; if ((c = channel_lookup(s->chanid)) == NULL) fatal("session_exit_message: session %d: no channel %d", s->self, s->chanid); debug("session_exit_message: session %d channel %d pid %ld", s->self, s->chanid, (long)s->pid); if (WIFEXITED(status)) { channel_request_start(s->chanid, "exit-status", 0); packet_put_int(WEXITSTATUS(status)); packet_send(); } else if (WIFSIGNALED(status)) { channel_request_start(s->chanid, "exit-signal", 0); packet_put_cstring(sig2name(WTERMSIG(status))); packet_put_char(WCOREDUMP(status)); packet_put_cstring(""); packet_put_cstring(""); packet_send(); } else { /* Some weird exit cause. Just exit. */ packet_disconnect("wait returned status %04x.", status); } /* disconnect channel */ debug("session_exit_message: release channel %d", s->chanid); channel_cancel_cleanup(s->chanid); /* * emulate a write failure with 'chan_write_failed', nobody will be * interested in data we write. * Note that we must not call 'chan_read_failed', since there could * be some more data waiting in the pipe. */ if (c->ostate != CHAN_OUTPUT_CLOSED) chan_write_failed(c); s->chanid = -1; } void session_close(Session *s) { debug("session_close: session %d pid %ld", s->self, (long)s->pid); if (s->ttyfd != -1) { fatal_remove_cleanup(session_pty_cleanup, (void *)s); session_pty_cleanup(s); } if (s->term) xfree(s->term); if (s->display) xfree(s->display); if (s->auth_display) xfree(s->auth_display); if (s->auth_data) xfree(s->auth_data); if (s->auth_proto) xfree(s->auth_proto); s->used = 0; session_proctitle(s); } void session_close_by_pid(pid_t pid, int status) { Session *s = session_by_pid(pid); if (s == NULL) { debug("session_close_by_pid: no session for pid %ld", (long)pid); return; } if (s->chanid != -1) session_exit_message(s, status); session_close(s); } /* * this is called when a channel dies before * the session 'child' itself dies */ void session_close_by_channel(int id, void *arg) { Session *s = session_by_channel(id); if (s == NULL) { debug("session_close_by_channel: no session for id %d", id); return; } debug("session_close_by_channel: channel %d child %ld", id, (long)s->pid); if (s->pid != 0) { debug("session_close_by_channel: channel %d: has child", id); /* * delay detach of session, but release pty, since * the fd's to the child are already closed */ if (s->ttyfd != -1) { fatal_remove_cleanup(session_pty_cleanup, (void *)s); session_pty_cleanup(s); } return; } /* detach by removing callback */ channel_cancel_cleanup(s->chanid); s->chanid = -1; session_close(s); } void session_destroy_all(void (*closefunc)(Session *)) { int i; for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (s->used) { if (closefunc != NULL) closefunc(s); else session_close(s); } } } static char * session_tty_list(void) { static char buf[1024]; int i; buf[0] = '\0'; for (i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (s->used && s->ttyfd != -1) { if (buf[0] != '\0') strlcat(buf, ",", sizeof buf); strlcat(buf, strrchr(s->tty, '/') + 1, sizeof buf); } } if (buf[0] == '\0') strlcpy(buf, "notty", sizeof buf); return buf; } void session_proctitle(Session *s) { if (s->pw == NULL) error("no user for session %d", s->self); else setproctitle("%s@%s", s->pw->pw_name, session_tty_list()); } int session_setup_x11fwd(Session *s) { struct stat st; char display[512], auth_display[512]; char hostname[MAXHOSTNAMELEN]; if (no_x11_forwarding_flag) { packet_send_debug("X11 forwarding disabled in user configuration file."); return 0; } if (!options.x11_forwarding) { debug("X11 forwarding disabled in server configuration file."); return 0; } if (!options.xauth_location || (stat(options.xauth_location, &st) == -1)) { packet_send_debug("No xauth program; cannot forward with spoofing."); return 0; } if (options.use_login) { packet_send_debug("X11 forwarding disabled; " "not compatible with UseLogin=yes."); return 0; } if (s->display != NULL) { debug("X11 display already set."); return 0; } if (x11_create_display_inet(options.x11_display_offset, options.x11_use_localhost, s->single_connection, &s->display_number) == -1) { debug("x11_create_display_inet failed."); return 0; } /* Set up a suitable value for the DISPLAY variable. */ if (gethostname(hostname, sizeof(hostname)) < 0) fatal("gethostname: %.100s", strerror(errno)); /* * auth_display must be used as the displayname when the * authorization entry is added with xauth(1). This will be * different than the DISPLAY string for localhost displays. */ if (options.x11_use_localhost) { snprintf(display, sizeof display, "localhost:%u.%u", s->display_number, s->screen); snprintf(auth_display, sizeof auth_display, "unix:%u.%u", s->display_number, s->screen); s->display = xstrdup(display); s->auth_display = xstrdup(auth_display); } else { snprintf(display, sizeof display, "%.400s:%u.%u", hostname, s->display_number, s->screen); s->display = xstrdup(display); s->auth_display = xstrdup(display); } return 1; } static void do_authenticated2(Authctxt *authctxt) { server_loop2(authctxt); }