/* * 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. */ /* * Copyright 2010 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ #include "includes.h" RCSID("$OpenBSD: session.c,v 1.150 2002/09/16 19:55:33 stevesk Exp $"); #ifdef HAVE_DEFOPEN #include #include #endif /* HAVE_DEFOPEN */ #ifdef HAVE_LIBGEN_H #include #endif #include #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 "tildexpand.h" #include "misc.h" #include "sftp.h" #ifdef USE_PAM #include #endif /* USE_PAM */ #ifdef GSSAPI #include "ssh-gss.h" #endif #ifdef ALTPRIVSEP #include "altprivsep.h" #endif /* ALTPRIVSEP */ #ifdef HAVE_CYGWIN #include #include #define is_winnt (GetVersion() < 0x80000000) #endif /* func */ Session *session_new(void); void session_set_fds(Session *, int, int, int); void session_pty_cleanup(void *); void session_xauthfile_cleanup(void *s); 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 *); static int session_env_req(Session *s); static void session_free_env(char ***envp); static void safely_chroot(const char *path, uid_t uid); static void drop_privs(uid_t uid); #ifdef USE_PAM static void session_do_pam(Session *, int); #endif /* USE_PAM */ /* import */ extern ServerOptions options; extern char *__progname; extern int log_stderr; extern int debug_flag; extern u_int utmp_len; extern void destroy_sensitive_data(void); #ifdef GSSAPI extern Gssctxt *xxx_gssctxt; #endif /* GSSAPI */ /* original command from peer. */ const char *original_command = NULL; /* data */ #define MAX_SESSIONS 10 Session sessions[MAX_SESSIONS]; #define SUBSYSTEM_NONE 0 #define SUBSYSTEM_EXT 1 #define SUBSYSTEM_INT_SFTP 2 #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, xstrdup("auth socket"), 1); strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); return 1; } void do_authenticated(Authctxt *authctxt) { /* 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. */ 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) { pid_t pid; 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)); 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)); /* * 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 (s->is_subsystem) { /* * Redirect the subsystem's stderr to /dev/null. We might send it * over to the other side but changing that might break existing * SSH clients. */ close(err[0]); if ((err[0] = open(_PATH_DEVNULL, O_WRONLY)) == -1) fatal("Cannot open /dev/null: %.100s", strerror(errno)); } if (dup2(err[0], 2) < 0) /* stderr */ perror("dup2 stderr"); #ifdef _UNICOS cray_init_job(s->pw); /* set up cray jid and tmpdir */ #endif /* Do processing for the child (exec command etc). */ do_child(s, command); /* NOTREACHED */ } #ifdef _UNICOS signal(WJSIGNAL, cray_job_termination_handler); #endif /* _UNICOS */ #ifdef HAVE_CYGWIN if (is_winnt) cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); #endif if (pid < 0) packet_disconnect("fork failed: %.100s", strerror(errno)); s->pid = pid; /* Set interactive/non-interactive mode. */ packet_set_interactive(s->display != NULL); /* 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]); if (s->is_subsystem) close(err[1]); /* Don't close channel before sending exit-status! */ channel_set_wait_for_exit(s->chanid, 1); } else { server_loop(pid, inout[1], inout[1], err[1]); /* server_loop has closed inout[1] and err[1]. */ } } /* * 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, pipe_fds[2]; pid_t pid; if (s == NULL) fatal("do_exec_pty: no session"); ptyfd = s->ptyfd; ttyfd = s->ttyfd; #ifdef USE_PAM session_do_pam(s, 1); /* pam_open_session() */ #endif /* USE_PAM */ /* * This pipe lets sshd wait for child to exec or exit. This is * particularly important for ALTPRIVSEP because the child is * the one to call the monitor to request a record_login() and * we don't want the child and the parent to compete for the * monitor's attention. But this is generic code and doesn't * hurt to have here even if ALTPRIVSEP is not used. */ if (pipe(pipe_fds) != 0) packet_disconnect("pipe failed: %.100s", strerror(errno)); (void) fcntl(pipe_fds[0], F_SETFD, FD_CLOEXEC); (void) fcntl(pipe_fds[1], F_SETFD, FD_CLOEXEC); /* Fork the child. */ if ((pid = fork()) == 0) { (void) close(pipe_fds[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) */ do_login(s, command); /* * Close the pipe to the parent so it can re-enter its event * loop and service the ptm; if enough debug messages get * written to the pty before this happens there will be a * deadlock. */ close(pipe_fds[1]); /* * do_motd() was called originally in do_login(). However, * when the /etc/motd file is large, a deadlock would happen, * because * - The child is blocked at fputs() to pty, when pty buffer * is full. * - The parent can not consume the pty buffer, because it is * still blocked at read(pipe_fds[0]). * * To resolve the deadlock issue, we defer do_motd() after * close(pipe_fds[1]). */ do_motd(); /* Do common processing for the child, such as execing the command. */ do_child(s, command); /* NOTREACHED */ } /* Wait for child to exec() or exit() */ (void) close(pipe_fds[1]); (void) read(pipe_fds[0], &pipe_fds[1], sizeof(int)); #ifdef _UNICOS signal(WJSIGNAL, cray_job_termination_handler); #endif /* _UNICOS */ #ifdef HAVE_CYGWIN if (is_winnt) cygwin_set_impersonation_token(INVALID_HANDLE_VALUE); #endif 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); /* Don't close channel before sending exit-status! */ channel_set_wait_for_exit(s->chanid, 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 (command) s->command = xstrdup(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; #ifndef ALTPRIVSEP struct passwd * pw = s->pw; #endif /* ALTPRIVSEP*/ pid_t pid = getpid(); /* Record that there was a login on that tty from the remote host. */ #ifdef ALTPRIVSEP debug3("Recording SSHv2 channel login in utmpx/wtmpx"); altprivsep_record_login(pid, s->tty); #endif /* ALTPRIVSEP*/ if (check_quietlogin(s, command)) return; #ifdef USE_PAM print_pam_messages(); #endif /* USE_PAM */ #ifdef WITH_AIXAUTHENTICATE if (aixloginmsg && *aixloginmsg) printf("%s\n", aixloginmsg); #endif /* WITH_AIXAUTHENTICATE */ #ifndef NO_SSH_LASTLOG 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); } #endif /* NO_SSH_LASTLOG */ } /* * 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. */ void child_set_env(char ***envp, u_int *envsizep, const char *name, const char *value) { debug3("child_set_env(%s, %s)", name, value); child_set_env_silent(envp, envsizep, name, value); } void child_set_env_silent(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, gettext("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); } void copy_environment(char **source, char ***env, u_int *envsize) { char *var_name, *var_val; int i; if (source == NULL) return; for(i = 0; source[i] != NULL; i++) { var_name = xstrdup(source[i]); if ((var_val = strstr(var_name, "=")) == NULL) { xfree(var_name); continue; } *var_val++ = '\0'; debug3("Copy environment: %s=%s", var_name, var_val); child_set_env(env, envsize, var_name, var_val); xfree(var_name); } } #ifdef HAVE_DEFOPEN static void deflt_do_setup_env(Session *s, const char *shell, char ***env, u_int *envsize) { int flags; char *ptr; mode_t Umask = 022; if (defopen(_PATH_DEFAULT_LOGIN)) return; /* Ignore case */ flags = defcntl(DC_GETFLAGS, 0); TURNOFF(flags, DC_CASE); (void) defcntl(DC_SETFLAGS, flags); /* TZ & HZ */ if ((ptr = defread("TIMEZONE=")) != NULL) child_set_env(env, envsize, "TZ", ptr); if ((ptr = defread("HZ=")) != NULL) child_set_env(env, envsize, "HZ", ptr); /* PATH */ if (s->pw->pw_uid != 0 && (ptr = defread("PATH=")) != NULL) child_set_env(env, envsize, "PATH", ptr); if (s->pw->pw_uid == 0 && (ptr = defread("SUPATH=")) != NULL) child_set_env(env, envsize, "PATH", ptr); /* SHELL */ if ((ptr = defread("ALTSHELL=")) != NULL) { if (strcasecmp("YES", ptr) == 0) child_set_env(env, envsize, "SHELL", shell); else child_set_env(env, envsize, "SHELL", ""); } /* UMASK */ if ((ptr = defread("UMASK=")) != NULL && sscanf(ptr, "%lo", &Umask) == 1 && Umask <= (mode_t)0777) (void) umask(Umask); else (void) umask(022); /* ULIMIT */ if ((ptr = defread("ULIMIT=")) != NULL && atol(ptr) > 0L && ulimit(UL_SETFSIZE, atol(ptr)) < 0L) error("Could not set ULIMIT to %ld from %s\n", atol(ptr), _PATH_DEFAULT_LOGIN); (void) defopen(NULL); } #endif /* HAVE_DEFOPEN */ static char ** do_setup_env(Session *s, const char *shell) { char buf[256]; char path_maildir[] = _PATH_MAILDIR; u_int i, envsize, pm_len; char **env; struct passwd *pw = s->pw; /* Initialize the environment. */ envsize = 100; env = xmalloc(envsize * sizeof(char *)); env[0] = NULL; #ifdef HAVE_CYGWIN /* * The Windows environment contains some setting which are * important for a running system. They must not be dropped. */ copy_environment(environ, &env, &envsize); #endif #ifdef GSSAPI /* Allow any GSSAPI methods that we've used to alter * the childs environment as they see fit */ ssh_gssapi_do_child(xxx_gssctxt, &env,&envsize); #endif /* 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 /* HAVE_LOGIN_CAP */ # ifndef HAVE_CYGWIN /* * There's no standard path on Windows. The path contains * important components pointing to the system directories, * needed for loading shared libraries. So the path better * remains intact here. */ # ifdef SUPERUSER_PATH child_set_env(&env, &envsize, "PATH", s->pw->pw_uid == 0 ? SUPERUSER_PATH : _PATH_STDPATH); # else child_set_env(&env, &envsize, "PATH", _PATH_STDPATH); # endif /* SUPERUSER_PATH */ # endif /* HAVE_CYGWIN */ #endif /* HAVE_LOGIN_CAP */ pm_len = strlen(path_maildir); if (path_maildir[pm_len - 1] == '/' && pm_len > 1) path_maildir[pm_len - 1] = NULL; 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); #ifdef HAVE_DEFOPEN deflt_do_setup_env(s, shell, &env, &envsize); #endif /* HAVE_DEFOPEN */ #define PASS_ENV(x) \ if (getenv(x)) \ child_set_env(&env, &envsize, x, getenv(x)); if (getenv("TZ")) child_set_env(&env, &envsize, "TZ", getenv("TZ")); if (s->auth_file != NULL) child_set_env(&env, &envsize, "XAUTHORITY", s->auth_file); PASS_ENV("LANG") PASS_ENV("LC_ALL") PASS_ENV("LC_CTYPE") PASS_ENV("LC_COLLATE") PASS_ENV("LC_TIME") PASS_ENV("LC_NUMERIC") PASS_ENV("LC_MONETARY") PASS_ENV("LC_MESSAGES") #undef PASS_ENV if (s->env != NULL) copy_environment(s->env, &env, &envsize); /* Set custom environment options from RSA authentication. */ 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); snprintf(buf, sizeof buf, "%.50s %d %.50s %d", get_remote_ipaddr(), get_remote_port(), get_local_ipaddr(packet_get_connection_in()), get_local_port()); 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 _UNICOS if (cray_tmpdir[0] != '\0') child_set_env(&env, &envsize, "TMPDIR", cray_tmpdir); #endif /* _UNICOS */ #ifdef _AIX { char *cp; if ((cp = getenv("AUTHSTATE")) != NULL) child_set_env(&env, &envsize, "AUTHSTATE", cp); if ((cp = getenv("KRB5CCNAME")) != NULL) child_set_env(&env, &envsize, "KRB5CCNAME", cp); read_environment_file(&env, &envsize, "/etc/environment"); } #endif #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 #ifdef USE_PAM /* * Pull in any environment variables that may have * been set by PAM. */ { char **p; p = fetch_pam_environment(s->authctxt); copy_environment(p, &env, &envsize); free_pam_environment(p); } #endif /* USE_PAM */ 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) { snprintf(buf, sizeof buf, "%.200s/.ssh/environment", strcmp(pw->pw_dir, "/") ? pw->pw_dir : ""); read_environment_file(&env, &envsize, buf); } if (debug_flag) { /* dump the environment */ fprintf(stderr, gettext("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 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, "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); } } } /* Disallow logins if /etc/nologin exists. This does not apply to root. */ static void do_nologin(struct passwd *pw) { FILE *f = NULL; char buf[1024]; struct stat sb; if (pw->pw_uid == 0) return; if (stat(_PATH_NOLOGIN, &sb) == -1) return; /* /etc/nologin exists. Print its contents if we can and exit. */ log("User %.100s not allowed because %s exists.", pw->pw_name, _PATH_NOLOGIN); if ((f = fopen(_PATH_NOLOGIN, "r")) != NULL) { while (fgets(buf, sizeof(buf), f)) fputs(buf, stderr); fclose(f); } exit(254); } /* Chroot into ChrootDirectory if the option is set. */ void chroot_if_needed(struct passwd *pw) { char *chroot_path, *tmp; if (chroot_requested(options.chroot_directory)) { tmp = tilde_expand_filename(options.chroot_directory, pw->pw_uid); chroot_path = percent_expand(tmp, "h", pw->pw_dir, "u", pw->pw_name, (char *)NULL); safely_chroot(chroot_path, pw->pw_uid); free(tmp); free(chroot_path); } } /* * Chroot into a directory after checking it for safety: all path components * must be root-owned directories with strict permissions. */ static void safely_chroot(const char *path, uid_t uid) { const char *cp; char component[MAXPATHLEN]; struct stat st; if (*path != '/') fatal("chroot path does not begin at root"); if (strlen(path) >= sizeof(component)) fatal("chroot path too long"); /* * Descend the path, checking that each component is a * root-owned directory with strict permissions. */ for (cp = path; cp != NULL;) { if ((cp = strchr(cp, '/')) == NULL) strlcpy(component, path, sizeof(component)); else { cp++; memcpy(component, path, cp - path); component[cp - path] = '\0'; } debug3("%s: checking '%s'", __func__, component); if (stat(component, &st) != 0) fatal("%s: stat(\"%s\"): %s", __func__, component, strerror(errno)); if (st.st_uid != 0 || (st.st_mode & 022) != 0) fatal("bad ownership or modes for chroot " "directory %s\"%s\"", cp == NULL ? "" : "component ", component); if (!S_ISDIR(st.st_mode)) fatal("chroot path %s\"%s\" is not a directory", cp == NULL ? "" : "component ", component); } if (chdir(path) == -1) fatal("Unable to chdir to chroot path \"%s\": " "%s", path, strerror(errno)); if (chroot(path) == -1) fatal("chroot(\"%s\"): %s", path, strerror(errno)); if (chdir("/") == -1) fatal("%s: chdir(/) after chroot: %s", __func__, strerror(errno)); verbose("Changed root directory to \"%s\"", path); } static void launch_login(struct passwd *pw, const char *hostname) { /* Launch login(1). */ execl(LOGIN_PROGRAM, "login", "-h", hostname, #ifdef xxxLOGIN_NEEDS_TERM (s->term ? s->term : "unknown"), #endif /* LOGIN_NEEDS_TERM */ #ifdef LOGIN_NO_ENDOPT "-p", "-f", pw->pw_name, (char *)NULL); #else "-p", "-f", "--", pw->pw_name, (char *)NULL); #endif /* 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. */ #define ARGV_MAX 10 void do_child(Session *s, const char *command) { extern char **environ; char **env; char *argv[ARGV_MAX]; const char *shell, *shell0; struct passwd *pw = s->pw; /* remove hostkey from the child's memory */ destroy_sensitive_data(); do_nologin(pw); chroot_if_needed(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; #ifdef HAVE_LOGIN_CAP shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell); #endif env = do_setup_env(s, shell); /* * 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(); /* * Must switch to the new environment variables so that .ssh/rc, * /etc/ssh/sshrc, and xauth are run in the proper environment. */ environ = env; /* * New environment has been installed. We need to update locale * so that error messages beyond this point have the proper * character encoding. */ (void) setlocale(LC_ALL, ""); /* * 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. */ closefrom(STDERR_FILENO + 1); #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) { /* Suppress missing homedir warning for chroot case */ if (!chroot_requested(options.chroot_directory)) fprintf(stderr, "Could not chdir to home " "directory %s: %s\n", pw->pw_dir, strerror(errno)); } do_rc_files(s, shell); /* restore SIGPIPE for child */ signal(SIGPIPE, SIG_DFL); if (s->is_subsystem == SUBSYSTEM_INT_SFTP) { int i; char *p, *args; extern int optind, optreset; /* This will set the E/P sets here, simulating exec(2). */ drop_privs(pw->pw_uid); setproctitle("%s@internal-sftp-server", s->pw->pw_name); args = xstrdup(command ? command : "sftp-server"); i = 0; for ((p = strtok(args, " ")); p != NULL; (p = strtok(NULL, " "))) { if (i < ARGV_MAX - 1) argv[i++] = p; } argv[i] = NULL; optind = optreset = 1; __progname = argv[0]; exit(sftp_server_main(i, argv, s->pw)); } /* 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; s->env = NULL; 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; } #ifndef lint 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; } #endif /* lint */ 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)); /* * PAM may update the last login date. * * Ideally PAM would also show the last login date as a * PAM_TEXT_INFO conversation message, and then we could just * always force the use of keyboard-interactive just so we can * pass any such PAM prompts and messages from the account and * session stacks, but skip pam_authenticate() if other userauth * has succeeded and the user's password isn't expired. * * Unfortunately this depends on support for keyboard- * interactive in the client, and support for lastlog messages * in some PAM module. * * As it is Solaris updates the lastlog in PAM, but does * not show the lastlog date in PAM. If and when this state of * affairs changes this hack can be reconsidered, and, maybe, * removed. * * So we're stuck with a crude hack: get the lastlog * time before calling pam_open_session() and store it * in the Authctxt and then use it here once. After * that, if the client opens any more pty sessions we'll * show the last lastlog entry since userauth. */ if (s->authctxt != NULL && s->authctxt->last_login_time > 0) { s->last_login_time = s->authctxt->last_login_time; (void) strlcpy(s->hostname, s->authctxt->last_login_host, sizeof(s->hostname)); s->authctxt->last_login_time = 0; s->authctxt->last_login_host[0] = '\0'; } } 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 (!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); 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 *prog, *cmd, *subsys = packet_get_string(&len); u_int i; packet_check_eom(); log("subsystem request for %.100s", subsys); for (i = 0; i < options.num_subsystems; i++) { if (strcmp(subsys, options.subsystem_name[i]) == 0) { prog = options.subsystem_command[i]; cmd = options.subsystem_args[i]; if (strcmp(INTERNAL_SFTP_NAME, prog) == 0) { s->is_subsystem = SUBSYSTEM_INT_SFTP; /* * We must stat(2) the subsystem before we chroot in * order to be able to send a proper error message. */ } else if (chroot_requested(options.chroot_directory)) { char chdirsub[MAXPATHLEN]; strlcpy(chdirsub, options.chroot_directory, sizeof (chdirsub)); strlcat(chdirsub, "/", sizeof (chdirsub)); strlcat(chdirsub, prog, sizeof (chdirsub)); if (stat(chdirsub, &st) < 0) { error("subsystem: cannot stat %s under " "chroot directory %s: %s", prog, options.chroot_directory, strerror(errno)); if (strcmp(subsys, "sftp") == 0) error("subsystem: please see " "the Subsystem option in " "sshd_config(4) for an " "explanation of '%s'.", INTERNAL_SFTP_NAME); break; } } else if (stat(prog, &st) < 0) { error("subsystem: cannot stat %s: %s", prog, strerror(errno)); break; } else { s->is_subsystem = SUBSYSTEM_EXT; } debug("subsystem: exec() %s", cmd); do_exec(s, cmd); success = 1; break; } } if (!success) log("subsystem request for %.100s failed, subsystem not found", subsys); xfree(subsys); return success; } /* * Serve "x11-req" channel request for X11 forwarding for the current session * channel. */ static int session_x11_req(Session *s) { int success, fd; char xauthdir[] = "/tmp/ssh-xauth-XXXXXX"; 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); } /* * Create per session X authority file so that different sessions * don't contend for one common file. The reason for this is that * xauth(1) locking doesn't work too well over network filesystems. * * If mkdtemp() or open() fails then s->auth_file remains NULL which * means that we won't set XAUTHORITY variable in child's environment * and xauth(1) will use the default location for the authority file. */ if (mkdtemp(xauthdir) != NULL) { s->auth_file = xmalloc(MAXPATHLEN); snprintf(s->auth_file, MAXPATHLEN, "%s/xauthfile", xauthdir); /* * we don't want that "creating new authority file" message to * be printed by xauth(1) so we must create that file * beforehand. */ if ((fd = open(s->auth_file, O_CREAT | O_EXCL | O_RDONLY, S_IRUSR | S_IWUSR)) == -1) { error("failed to create the temporary X authority " "file %s: %.100s; will use the default one", s->auth_file, strerror(errno)); xfree(s->auth_file); s->auth_file = NULL; if (rmdir(xauthdir) == -1) { error("cannot remove xauth directory %s: %.100s", xauthdir, strerror(errno)); } } else { close(fd); debug("temporary X authority file %s created", s->auth_file); /* * add a cleanup function to remove the temporary * xauth file in case we call fatal() (e.g., the * connection gets closed). */ fatal_add_cleanup(session_xauthfile_cleanup, (void *)s); } } else { error("failed to create a directory for the temporary X " "authority file: %.100s; will use the default xauth file", strerror(errno)); } 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); } } static int session_loc_env_check(char *var, char *val) { char *current; int cat, ret; if (strcmp(var, "LANG") == 0) cat = LC_ALL; else if (strcmp(var, "LC_ALL") == 0) cat = LC_ALL; else if (strcmp(var, "LC_CTYPE") == 0) cat = LC_CTYPE; else if (strcmp(var, "LC_COLLATE") == 0) cat = LC_COLLATE; else if (strcmp(var, "LC_TIME") == 0) cat = LC_TIME; else if (strcmp(var, "LC_NUMERIC") == 0) cat = LC_NUMERIC; else if (strcmp(var, "LC_MONETARY") == 0) cat = LC_MONETARY; else if (strcmp(var, "LC_MESSAGES") == 0) cat = LC_MESSAGES; current = setlocale(cat, NULL); ret = (setlocale(cat, val) != NULL); (void) setlocale(cat, current); return (ret); } static int session_env_req(Session *s) { Channel *c; char *var, *val, *e; char **p; size_t len; int ret = 0; /* Get var/val from the rest of this packet */ var = packet_get_string(NULL); val = packet_get_string(NULL); /* * We'll need the channel ID for the packet_send_debug messages, * so get it now. */ if ((c = channel_lookup(s->chanid)) == NULL) goto done; /* shouldn't happen! */ debug2("Received request for environment variable %s=%s", var, val); /* For now allow only LANG and LC_* */ if (strcmp(var, "LANG") != 0 && strncmp(var, "LC_", 3) != 0) { debug2("Rejecting request for environment variable %s", var); goto done; } if (!session_loc_env_check(var, val)) { packet_send_debug(gettext("Missing locale support for %s=%s"), var, val); goto done; } packet_send_debug(gettext("Channel %d set: %s=%s"), c->remote_id, var, val); /* * Always append new environment variables without regard to old * ones being overriden. The way these are actually added to * the environment of the session process later settings * override earlier ones; see copy_environment(). */ if (s->env == NULL) { char **env; env = xmalloc(sizeof (char **) * 2); memset(env, 0, sizeof (char **) * 2); s->env = env; p = env; } else { for (p = s->env; *p != NULL ; p++); s->env = xrealloc(s->env, (p - s->env + 2) * sizeof (char **)); for (p = s->env; *p != NULL ; p++); } len = snprintf(NULL, 0, "%s=%s", var, val); e = xmalloc(len + 1); (void) snprintf(e, len + 1, "%s=%s", var, val); (*p++) = e; *p = NULL; ret = 1; done: xfree(var); xfree(val); return (ret); } static void session_free_env(char ***envp) { char **env, **p; if (envp == NULL || *envp == NULL) return; env = *envp; *envp = NULL; for (p = env; *p != NULL; p++) xfree(*p); xfree(env); } int session_input_channel_req(Channel *c, const char *rtype) { int success = 0; Session *s; if ((s = session_by_channel(c->self)) == NULL) { log("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); } else if (strcmp(rtype, "env") == 0) { success = session_env_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); #ifdef USE_PAM session_do_pam(s, 0); #endif /* USE_PAM */ /* Record that the user has logged out. */ if (s->pid != 0) { debug3("Recording SSHv2 channel logout in utmpx/wtmpx"); #ifdef ALTPRIVSEP altprivsep_record_logout(s->pid); #endif /* ALTPRIVSEP */ } /* 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) { session_pty_cleanup2(session); } /* * We use a different temporary X authority file per every session so we * should remove those files when fatal() is called. */ void session_xauthfile_cleanup(void *session) { Session *s = session; if (s == NULL) { error("session_xauthfile_cleanup: no session"); return; } debug("session_xauthfile_cleanup: session %d removing %s", s->self, s->auth_file); if (unlink(s->auth_file) == -1) { error("session_xauthfile_cleanup: cannot remove xauth file: " "%.100s", strerror(errno)); return; } /* dirname() will modify s->auth_file but that's ok */ if (rmdir(dirname(s->auth_file)) == -1) { error("session_xauthfile_cleanup: " "cannot remove xauth directory: %.100s", strerror(errno)); return; } } 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))); #ifdef WCOREDUMP packet_put_char(WCOREDUMP(status)); #else /* WCOREDUMP */ packet_put_char(0); #endif /* WCOREDUMP */ packet_put_cstring(""); packet_put_cstring(""); packet_send(); } else { /* Some weird exit cause. Just exit. */ packet_disconnect("wait returned status %04x.", status); } /* Ok to close channel now */ channel_set_wait_for_exit(s->chanid, 0); /* 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->auth_file != NULL) { fatal_remove_cleanup(session_xauthfile_cleanup, (void *)s); session_xauthfile_cleanup(s); xfree(s->auth_file); } 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); if (s->command) xfree(s->command); session_free_env(&s->env); 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. * It can happen for example if we exit from an interactive shell before we * exit from forwarded X11 applications. */ 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 (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 { #ifdef IPADDR_IN_DISPLAY struct hostent *he; struct in_addr my_addr; he = gethostbyname(hostname); if (he == NULL) { error("Can't get IP address for X11 DISPLAY."); packet_send_debug("Can't get IP address for X11 DISPLAY."); return 0; } memcpy(&my_addr, he->h_addr_list[0], sizeof(struct in_addr)); snprintf(display, sizeof display, "%.50s:%u.%u", inet_ntoa(my_addr), s->display_number, s->screen); #else snprintf(display, sizeof display, "%.400s:%u.%u", hostname, s->display_number, s->screen); #endif s->display = xstrdup(display); s->auth_display = xstrdup(display); } return 1; } #ifdef USE_PAM int session_do_pam_conv(int, struct pam_message **, struct pam_response **, void *); static struct pam_conv session_pam_conv = { session_do_pam_conv, NULL }; static void session_do_pam(Session *s, int do_open) { int pam_retval; char *where, *old_tty, *old_tty_copy = NULL; struct pam_conv old_conv, *old_conv_ptr; if (!s || !s->authctxt || !s->authctxt->pam || !s->authctxt->pam->h) return; /* Save current PAM item values */ where = "getting PAM_CONV"; pam_retval = pam_get_item(s->authctxt->pam->h, PAM_CONV, (void **) &old_conv_ptr); if (pam_retval != PAM_SUCCESS) goto done; old_conv = *old_conv_ptr; where = "getting PAM_TTY"; pam_retval = pam_get_item(s->authctxt->pam->h, PAM_TTY, (void **) &old_tty); if (pam_retval != PAM_SUCCESS) goto done; old_tty_copy = xstrdup(old_tty); /* Change PAM_TTY and PAM_CONV items */ where = "setting PAM_TTY"; pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, s->tty); if (pam_retval != PAM_SUCCESS) goto done; where = "setting PAM_CONV"; session_pam_conv.appdata_ptr = s; pam_retval = pam_set_item(s->authctxt->pam->h, PAM_CONV, &session_pam_conv); if (pam_retval != PAM_SUCCESS) goto done; /* Call pam_open/close_session() */ if (do_open) { where = "calling pam_open_session()"; pam_retval = pam_open_session(s->authctxt->pam->h, 0); } else { where = "calling pam_close_session()"; pam_retval = pam_close_session(s->authctxt->pam->h, 0); } /* Reset PAM_TTY and PAM_CONV items to previous values */ where = "setting PAM_TTY"; pam_retval = pam_set_item(s->authctxt->pam->h, PAM_TTY, old_tty_copy); if (pam_retval != PAM_SUCCESS) goto done; where = "setting PAM_CONV"; pam_retval = pam_set_item(s->authctxt->pam->h, PAM_CONV, &old_conv); if (pam_retval != PAM_SUCCESS) goto done; session_pam_conv.appdata_ptr = NULL; done: if (old_tty_copy) xfree(old_tty_copy); if (pam_retval == PAM_SUCCESS) return; /* fatal()? probably not... */ log("PAM failed[%d] while %s: %s", pam_retval, where, PAM_STRERROR(s->authctxt->pam->h, pam_retval)); } int session_do_pam_conv(int num_prompts, struct pam_message **prompts, struct pam_response **resp, void *app_data) { Session *s = (Session *) app_data; struct pam_response *reply; int count; char *prompt; if (channel_lookup(s->chanid) == NULL) return PAM_CONV_ERR; /* PAM will free this later */ reply = xmalloc(num_prompts * sizeof(*reply)); (void) memset(reply, 0, num_prompts * sizeof(*reply)); for (count = 0; count < num_prompts; count++) { switch(PAM_MSG_MEMBER(prompts, count, msg_style)) { case PAM_TEXT_INFO: /* Write to stdout of channel */ prompt = PAM_MSG_MEMBER(prompts, count, msg); if (prompt != NULL && s->ttyfd != -1) { debug2("session_do_pam_conv: text info " "prompt: %s", prompt); (void) write(s->ttyfd, prompt, strlen(prompt)); (void) write(s->ttyfd, "\n", 1); } reply[count].resp = xstrdup(""); reply[count].resp_retcode = PAM_SUCCESS; break; case PAM_ERROR_MSG: /* Write to stderr of channel */ prompt = PAM_MSG_MEMBER(prompts, count, msg); if (prompt != NULL && s->ttyfd != -1) { debug2("session_do_pam_conv: error " "prompt: %s", prompt); (void) write(s->ttyfd, prompt, strlen(prompt)); (void) write(s->ttyfd, "\n", 1); } reply[count].resp = xstrdup(""); reply[count].resp_retcode = PAM_SUCCESS; break; case PAM_PROMPT_ECHO_ON: case PAM_PROMPT_ECHO_OFF: /* * XXX Someday add support for echo on/off prompts * here on sessions with ttys. */ default: xfree(reply); return PAM_CONV_ERR; } } *resp = reply; return PAM_SUCCESS; } #endif /* USE_PAM */ static void do_authenticated2(Authctxt *authctxt) { server_loop2(authctxt); } /* * Drop the privileges. We need this for the in-process SFTP server only. For * the shell and the external subsystem the exec(2) call will do the P = E = I * assignment itself. Never change the privileges if the connecting user is * root. See privileges(5) if the terminology used here is not known to you. */ static void drop_privs(uid_t uid) { priv_set_t *priv_inherit; /* If root is connecting we are done. */ if (uid == 0) return; if ((priv_inherit = priv_allocset()) == NULL) fatal("priv_allocset: %s", strerror(errno)); if (getppriv(PRIV_INHERITABLE, priv_inherit) != 0) fatal("getppriv: %s", strerror(errno)); /* * This will limit E as well. Note that before this P was a * superset of I, see permanently_set_uid(). */ if (setppriv(PRIV_SET, PRIV_PERMITTED, priv_inherit) == -1) fatal("setppriv: %s", strerror(errno)); priv_freeset(priv_inherit); /* * By manipulating the P set above we entered a PA mode which we * do not need to retain in. */ if (setpflags(PRIV_AWARE, 0) == -1) fatal("setpflags: %s", strerror(errno)); }