/* * 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 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 1.48 2001/01/13 18:43:31 markus Exp $"); #include "xmalloc.h" #include "ssh.h" #include "pty.h" #include "packet.h" #include "buffer.h" #include "mpaux.h" #include "servconf.h" #include "uidswap.h" #include "compat.h" #include "channels.h" #include "nchan.h" #include "bufaux.h" #include "ssh2.h" #include "auth.h" #include "auth-options.h" #ifdef HAVE_LOGIN_CAP #include #endif /* types */ #define TTYSZ 64 typedef struct Session Session; struct Session { int used; int self; int extended; struct passwd *pw; pid_t pid; /* tty */ char *term; int ptyfd, ttyfd, ptymaster; int row, col, xpixel, ypixel; char tty[TTYSZ]; /* X11 */ char *display; int screen; char *auth_proto; char *auth_data; int single_connection; /* proto 2 */ int chanid; }; /* func */ Session *session_new(void); void session_set_fds(Session *s, int fdin, int fdout, int fderr); void session_pty_cleanup(Session *s); void session_proctitle(Session *s); void do_exec_pty(Session *s, const char *command, struct passwd * pw); void do_exec_no_pty(Session *s, const char *command, struct passwd * pw); void do_login(Session *s, const char *command); 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); /* import */ extern ServerOptions options; extern char *__progname; extern int log_stderr; extern int debug_flag; extern u_int utmp_len; extern int startup_pipe; /* Local Xauthority file. */ static char *xauthfile; /* original command from peer. */ char *original_command = NULL; /* data */ #define MAX_SESSIONS 10 Session sessions[MAX_SESSIONS]; #ifdef HAVE_LOGIN_CAP static login_cap_t *lc; #endif /* * Remove local Xauthority file. */ void xauthfile_cleanup_proc(void *ignore) { debug("xauthfile_cleanup_proc called"); if (xauthfile != NULL) { char *p; unlink(xauthfile); p = strrchr(xauthfile, '/'); if (p != NULL) { *p = '\0'; rmdir(xauthfile); } xfree(xauthfile); xauthfile = NULL; } } /* * Function to perform cleanup if we get aborted abnormally (e.g., due to a * dropped connection). */ void pty_cleanup_proc(void *session) { Session *s=session; if (s == NULL) fatal("pty_cleanup_proc: no session"); debug("pty_cleanup_proc: %s", s->tty); if (s->pid != 0) { /* Record that the user has logged out. */ record_logout(s->pid, s->tty); } /* Release the pseudo-tty. */ pty_release(s->tty); } /* * 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) { Session *s; int type, fd; int compression_level = 0, enable_compression_after_reply = 0; int have_pty = 0; char *command; int n_bytes; int plen; u_int proto_len, data_len, dlen; /* * Cancel the alarm we set to limit the time taken for * authentication. */ alarm(0); if (startup_pipe != -1) { close(startup_pipe); startup_pipe = -1; } /* * 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.) */ if (!no_port_forwarding_flag && options.allow_tcp_forwarding) channel_permit_all_opens(); s = session_new(); s->pw = pw; #ifdef HAVE_LOGIN_CAP if ((lc = login_getclass(pw->pw_class)) == NULL) { error("unable to get login class"); return; } #endif /* * We stay in this loop until the client requests to execute a shell * or a command. */ for (;;) { int success = 0; /* 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); break; } /* Enable compression after we have responded with SUCCESS. */ enable_compression_after_reply = 1; success = 1; break; case SSH_CMSG_REQUEST_PTY: if (no_pty_flag) { debug("Allocating a pty not permitted for this authentication."); break; } if (have_pty) packet_disconnect("Protocol error: you already have a pty."); debug("Allocating pty."); /* Allocate a pty and open it. */ if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) { error("Failed to allocate pty."); break; } fatal_add_cleanup(pty_cleanup_proc, (void *)s); pty_setowner(pw, s->tty); /* Get TERM from the packet. Note that the value may be of arbitrary length. */ s->term = packet_get_string(&dlen); packet_integrity_check(dlen, strlen(s->term), type); /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */ /* Remaining bytes */ n_bytes = plen - (4 + dlen + 4 * 4); if (strcmp(s->term, "") == 0) { xfree(s->term); s->term = NULL; } /* Get window size from the packet. */ s->row = packet_get_int(); s->col = packet_get_int(); s->xpixel = packet_get_int(); s->ypixel = packet_get_int(); pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); /* Get tty modes from the packet. */ tty_parse_modes(s->ttyfd, &n_bytes); packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type); session_proctitle(s); /* Indicate that we now have a pty. */ success = 1; have_pty = 1; break; case SSH_CMSG_X11_REQUEST_FORWARDING: if (!options.x11_forwarding) { packet_send_debug("X11 forwarding disabled in server configuration file."); break; } if (!options.xauth_location) { packet_send_debug("No xauth program; cannot forward with spoofing."); break; } if (no_x11_forwarding_flag) { packet_send_debug("X11 forwarding not permitted for this authentication."); break; } debug("Received request for X11 forwarding with auth spoofing."); if (s->display != NULL) packet_disconnect("Protocol error: X11 display already set."); s->auth_proto = packet_get_string(&proto_len); s->auth_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) s->screen = packet_get_int(); else s->screen = 0; s->display = x11_create_display_inet(s->screen, options.x11_display_offset); if (s->display == NULL) break; /* Setup to always have a local .Xauthority. */ xauthfile = xmalloc(MAXPATHLEN); strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); temporarily_use_uid(pw->pw_uid); if (mkdtemp(xauthfile) == NULL) { restore_uid(); error("private X11 dir: mkdtemp %s failed: %s", xauthfile, strerror(errno)); xfree(xauthfile); xauthfile = NULL; /* XXXX remove listening channels */ break; } strlcat(xauthfile, "/cookies", MAXPATHLEN); fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600); if (fd >= 0) close(fd); restore_uid(); fatal_add_cleanup(xauthfile_cleanup_proc, NULL); success = 1; 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(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(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; 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); packet_integrity_check(plen, 4 + dlen, type); } else { command = NULL; packet_integrity_check(plen, 0, type); } if (forced_command != NULL) { original_command = command; command = forced_command; debug("Forced command '%.500s'", forced_command); } if (have_pty) do_exec_pty(s, command, pw); else do_exec_no_pty(s, command, pw); if (command != NULL) xfree(command); /* Cleanup user's local Xauthority file. */ if (xauthfile) xauthfile_cleanup_proc(NULL); 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); } 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, struct passwd * pw) { 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 */ if (s == NULL) fatal("do_exec_no_pty: no session"); session_proctitle(s); /* Fork the child. */ if ((pid = fork()) == 0) { /* 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(command, pw, NULL, s->display, s->auth_proto, s->auth_data, NULL); /* 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->extended ? perr[0] : -1); } else { /* 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. */ if (compat20) { session_set_fds(s, inout[1], inout[1], s->extended ? err[1] : -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, struct passwd * pw) { 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) { /* 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 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); /* 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(command, pw, s->term, s->display, s->auth_proto, s->auth_data, s->tty); /* 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. */ session_pty_cleanup(s); } } const char * get_remote_name_or_ip(void) { static const char *remote = ""; if (utmp_len > 0) remote = get_canonical_hostname(); if (utmp_len == 0 || strlen(remote) > utmp_len) remote = get_remote_ipaddr(); return remote; } /* administrative, login(1)-like work */ void do_login(Session *s, const char *command) { FILE *f; char *time_string; char buf[256]; char hostname[MAXHOSTNAMELEN]; socklen_t fromlen; struct sockaddr_storage from; struct stat st; time_t last_login_time; 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)); if (packet_connection_is_on_socket()) { fromlen = sizeof(from); if (getpeername(packet_get_connection_in(), (struct sockaddr *) & from, &fromlen) < 0) { debug("getpeername: %.100s", strerror(errno)); fatal_cleanup(); } } /* Get the time and hostname when the user last logged in. */ hostname[0] = '\0'; last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name, hostname, sizeof(hostname)); /* Record that there was a login on that tty from the remote host. */ record_login(pid, s->tty, pw->pw_name, pw->pw_uid, get_remote_name_or_ip(), (struct sockaddr *)&from); /* Done if .hushlogin exists or a command given. */ if (command != NULL) return; snprintf(buf, sizeof(buf), "%.200s/.hushlogin", pw->pw_dir); #ifdef HAVE_LOGIN_CAP if (login_getcapbool(lc, "hushlogin", 0) || stat(buf, &st) >= 0) #else if (stat(buf, &st) >= 0) #endif return; if (last_login_time != 0) { time_string = ctime(&last_login_time); if (strchr(time_string, '\n')) *strchr(time_string, '\n') = 0; if (strcmp(hostname, "") == 0) printf("Last login: %s\r\n", time_string); else printf("Last login: %s from %s\r\n", time_string, hostname); } 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); } } } /* * 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, 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) { (*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, u_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); } /* * 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, *hostname = NULL, *cp = NULL; char buf[256]; char cmd[1024]; FILE *f = NULL; u_int envsize, i; char **env; extern char **environ; struct stat st; char *argv[10]; /* login(1) is only called if we execute the login shell */ if (options.use_login && command != NULL) options.use_login = 0; if (!options.use_login) { #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. */ while (fgets(buf, sizeof(buf), f)) fputs(buf, stderr); fclose(f); exit(254); } } /* Set login name, 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) { #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->pw_uid); #endif } if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) fatal("Failed to set uids to %u.", (u_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 HAVE_LOGIN_CAP shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); #endif #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); #ifdef HAVE_LOGIN_CAP (void) setusercontext(lc, pw, pw->pw_uid, LOGIN_SETPATH); 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. */ 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); if (original_command) child_set_env(&env, &envsize, "SSH_ORIGINAL_COMMAND", original_command); #ifdef KRB4 { extern char *ticket; if (ticket) child_set_env(&env, &envsize, "KRBTKFILE", ticket); } #endif /* KRB4 */ 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 $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]); } /* we have to stash the hostname before we close our socket. */ if (options.use_login) hostname = get_remote_name_or_ip(); /* * 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)); #ifdef HAVE_LOGIN_CAP if (login_getcapbool(lc, "requirehome", 0)) exit(1); #endif } /* * 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 %s %s\n", _PATH_BSHELL, SSH_USER_RC); f = popen(_PATH_BSHELL " " 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 %s %s\n", _PATH_BSHELL, SSH_SYSTEM_RC); f = popen(_PATH_BSHELL " " 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); } else if (options.xauth_location != NULL) { /* Add authority data to .Xauthority if appropriate. */ if (auth_proto != NULL && auth_data != NULL) { char *screen = strchr(display, ':'); if (debug_flag) { fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n", options.xauth_location, display, auth_proto, auth_data); if (screen != NULL) fprintf(stderr, "Adding %.*s/unix%s %s %s\n", (int)(screen-display), display, screen, auth_proto, auth_data); } snprintf(cmd, sizeof cmd, "%s -q -", options.xauth_location); f = popen(cmd, "w"); if (f) { fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data); if (screen != NULL) fprintf(f, "add %.*s/unix%s %s %s\n", (int)(screen-display), display, screen, auth_proto, auth_data); pclose(f); } else { fprintf(stderr, "Could not run %s\n", cmd); } } } /* 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("/usr/bin/login", "login", "-h", hostname, "-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); } 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; sessions[i].self = i; } did_init = 1; } for(i = 0; i < MAX_SESSIONS; i++) { Session *s = &sessions[i]; if (! s->used) { s->pid = 0; s->extended = 0; s->chanid = -1; s->ptyfd = -1; s->ttyfd = -1; s->term = NULL; s->pw = NULL; s->display = NULL; s->screen = 0; s->auth_data = NULL; s->auth_proto = NULL; s->used = 1; s->pw = NULL; debug("session_new: session %d", i); return s; } } return NULL; } 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 %d", s->used, s->self, s, s->chanid, s->pid); } } int session_open(int chanid) { Session *s = session_new(); debug("session_open: channel %d", chanid); if (s == NULL) { error("no more sessions"); return 0; } s->pw = auth_get_user(); if (s->pw == NULL) fatal("no user for session %i", s->self); debug("session_open: session %d: link with channel %d", s->self, chanid); s->chanid = chanid; return 1; } 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; } Session * session_by_pid(pid_t pid) { int i; debug("session_by_pid: pid %d", 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 %d", pid); session_dump(); return NULL; } 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_done(); pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); return 1; } int session_pty_req(Session *s) { u_int len; char *term_modes; /* encoded terminal modes */ if (no_pty_flag) return 0; if (s->ttyfd != -1) return 0; s->term = packet_get_string(&len); s->col = packet_get_int(); s->row = packet_get_int(); s->xpixel = packet_get_int(); s->ypixel = packet_get_int(); term_modes = packet_get_string(&len); packet_done(); if (strcmp(s->term, "") == 0) { xfree(s->term); s->term = NULL; } /* Allocate a pty and open it. */ if (!pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty))) { xfree(s->term); s->term = NULL; s->ptyfd = -1; s->ttyfd = -1; error("session_pty_req: session %d alloc failed", s->self); xfree(term_modes); return 0; } debug("session_pty_req: session %d alloc %s", s->self, s->tty); /* * 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(pty_cleanup_proc, (void *)s); pty_setowner(s->pw, s->tty); /* Get window size from the packet. */ pty_change_window_size(s->ptyfd, s->row, s->col, s->xpixel, s->ypixel); session_proctitle(s); /* XXX parse and set terminal modes */ xfree(term_modes); return 1; } int session_subsystem_req(Session *s) { u_int len; int success = 0; char *subsys = packet_get_string(&len); int i; packet_done(); log("subsystem request for %s", subsys); for (i = 0; i < options.num_subsystems; i++) { if(strcmp(subsys, options.subsystem_name[i]) == 0) { debug("subsystem: exec() %s", options.subsystem_command[i]); do_exec_no_pty(s, options.subsystem_command[i], s->pw); success = 1; } } if (!success) log("subsystem request for %s failed, subsystem not found", subsys); xfree(subsys); return success; } int session_x11_req(Session *s) { int fd; if (no_x11_forwarding_flag) { 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 (xauthfile != NULL) { debug("X11 fwd already started."); return 0; } debug("Received request for X11 forwarding with auth spoofing."); if (s->display != NULL) packet_disconnect("Protocol error: X11 display already set."); 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_done(); s->display = x11_create_display_inet(s->screen, options.x11_display_offset); if (s->display == NULL) { xfree(s->auth_proto); xfree(s->auth_data); return 0; } xauthfile = xmalloc(MAXPATHLEN); strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN); temporarily_use_uid(s->pw->pw_uid); if (mkdtemp(xauthfile) == NULL) { restore_uid(); error("private X11 dir: mkdtemp %s failed: %s", xauthfile, strerror(errno)); xfree(xauthfile); xauthfile = NULL; xfree(s->auth_proto); xfree(s->auth_data); /* XXXX remove listening channels */ return 0; } strlcat(xauthfile, "/cookies", MAXPATHLEN); fd = open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600); if (fd >= 0) close(fd); restore_uid(); fatal_add_cleanup(xauthfile_cleanup_proc, s); return 1; } int session_shell_req(Session *s) { /* if forced_command == NULL, the shell is execed */ char *shell = forced_command; packet_done(); s->extended = 1; if (s->ttyfd == -1) do_exec_no_pty(s, shell, s->pw); else do_exec_pty(s, shell, s->pw); return 1; } int session_exec_req(Session *s) { u_int len; char *command = packet_get_string(&len); packet_done(); if (forced_command) { original_command = command; command = forced_command; debug("Forced command '%.500s'", forced_command); } s->extended = 1; if (s->ttyfd == -1) do_exec_no_pty(s, command, s->pw); else do_exec_pty(s, command, s->pw); if (forced_command == NULL) xfree(command); return 1; } int session_auth_agent_req(Session *s) { static int called = 0; packet_done(); 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); } } void session_input_channel_req(int id, void *arg) { u_int len; int reply; int success = 0; char *rtype; Session *s; Channel *c; rtype = packet_get_string(&len); reply = packet_get_char(); s = session_by_channel(id); if (s == NULL) fatal("session_input_channel_req: channel %d: no session", id); c = channel_lookup(id); if (c == NULL) fatal("session_input_channel_req: channel %d: bad channel", id); debug("session_input_channel_req: session %d channel %d request %s reply %d", s->self, id, rtype, reply); /* * a session is in LARVAL state until a shell * or programm 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); } if (reply) { packet_start(success ? SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); packet_put_int(c->remote_id); packet_send(); } xfree(rtype); } 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); } void session_pty_cleanup(Session *s) { if (s == NULL || s->ttyfd == -1) return; debug("session_pty_cleanup: session %i release %s", s->self, s->tty); /* Cancel the cleanup function. */ fatal_remove_cleanup(pty_cleanup_proc, (void *)s); /* Record that the user has logged out. */ record_logout(s->pid, s->tty); /* Release the pseudo-tty. */ 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): %s", strerror(errno)); } void session_exit_message(Session *s, int status) { Channel *c; if (s == NULL) fatal("session_close: no session"); c = channel_lookup(s->chanid); if (c == NULL) fatal("session_close: session %d: no channel %d", s->self, s->chanid); debug("session_exit_message: session %d channel %d pid %d", s->self, s->chanid, 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_int(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_free(Session *s) { debug("session_free: session %d pid %d", s->self, s->pid); if (s->term) xfree(s->term); if (s->display) xfree(s->display); if (s->auth_data) xfree(s->auth_data); if (s->auth_proto) xfree(s->auth_proto); s->used = 0; } void session_close(Session *s) { session_pty_cleanup(s); session_free(s); 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 %d", s->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 channel %d", id); return; } /* disconnect channel */ channel_cancel_cleanup(s->chanid); s->chanid = -1; debug("session_close_by_channel: channel %d kill %d", id, s->pid); if (s->pid == 0) { /* close session immediately */ session_close(s); } else { /* notify child, delay session cleanup */ if (kill(s->pid, (s->ttyfd == -1) ? SIGTERM : SIGHUP) < 0) error("session_close_by_channel: kill %d: %s", s->pid, strerror(errno)); } } 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()); } void do_authenticated2(void) { struct passwd *pw; /* * Cancel the alarm we set to limit the time taken for * authentication. */ alarm(0); if (startup_pipe != -1) { close(startup_pipe); startup_pipe = -1; } #ifdef HAVE_LOGIN_CAP pw = auth_get_user(); if ((lc = login_getclass(pw->pw_class)) == NULL) { error("unable to get login class"); return; } #endif server_loop2(); if (xauthfile) xauthfile_cleanup_proc(NULL); }