diff options
| -rw-r--r-- | ChangeLog | 17 | ||||
| -rw-r--r-- | monitor.c | 4 | ||||
| -rw-r--r-- | monitor_wrap.c | 22 | ||||
| -rw-r--r-- | servconf.c | 21 | ||||
| -rw-r--r-- | servconf.h | 4 | ||||
| -rw-r--r-- | session.c | 382 | ||||
| -rw-r--r-- | session.h | 4 | ||||
| -rw-r--r-- | sshd_config | 3 | ||||
| -rw-r--r-- | sshd_config.5 | 7 |
9 files changed, 326 insertions, 138 deletions
@@ -77,6 +77,21 @@ shouldn't happen in compliant implementations, but it could be abused to leak memory. ok markus@ (as part of a larger diff) + - djm@cvs.openbsd.org 2008/05/08 12:21:16 + [monitor.c monitor_wrap.c session.h servconf.c servconf.h session.c] + [sshd_config sshd_config.5] + Make the maximum number of sessions run-time controllable via + a sshd_config MaxSessions knob. This is useful for disabling + login/shell/subsystem access while leaving port-forwarding working + (MaxSessions 0), disabling connection multiplexing (MaxSessions 1) or + simply increasing the number of allows multiplexed sessions. + Because some bozos are sure to configure MaxSessions in excess of the + number of available file descriptors in sshd (which, at peak, might be + as many as 9*MaxSessions), audit sshd to ensure that it doesn't leak fds + on error paths, and make it fail gracefully on out-of-fd conditions - + sending channel errors instead of than exiting with fatal(). + bz#1090; MaxSessions config bits and manpage from junyer AT gmail.com + ok markus@ 20080403 - (djm) [openbsd-compat/bsd-poll.c] Include stdlib.h to avoid compile- @@ -3937,4 +3952,4 @@ OpenServer 6 and add osr5bigcrypt support so when someone migrates passwords between UnixWare and OpenServer they will still work. OK dtucker@ -$Id: ChangeLog,v 1.4922 2008/05/19 05:28:35 djm Exp $ +$Id: ChangeLog,v 1.4923 2008/05/19 05:34:50 djm Exp $ @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor.c,v 1.95 2008/05/08 12:02:23 djm Exp $ */ +/* $OpenBSD: monitor.c,v 1.96 2008/05/08 12:21:16 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> * Copyright 2002 Markus Friedl <markus@openbsd.org> @@ -1273,7 +1273,7 @@ mm_session_close(Session *s) debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd); session_pty_cleanup2(s); } - s->used = 0; + session_unused(s->self); } int diff --git a/monitor_wrap.c b/monitor_wrap.c index 72fd5c83..e65fb127 100644 --- a/monitor_wrap.c +++ b/monitor_wrap.c @@ -1,4 +1,4 @@ -/* $OpenBSD: monitor_wrap.c,v 1.61 2008/05/08 12:02:23 djm Exp $ */ +/* $OpenBSD: monitor_wrap.c,v 1.62 2008/05/08 12:21:16 djm Exp $ */ /* * Copyright 2002 Niels Provos <provos@citi.umich.edu> * Copyright 2002 Markus Friedl <markus@openbsd.org> @@ -666,7 +666,20 @@ mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen) { Buffer m; char *p, *msg; - int success = 0; + int success = 0, tmp1 = -1, tmp2 = -1; + + /* Kludge: ensure there are fds free to receive the pty/tty */ + if ((tmp1 = dup(pmonitor->m_recvfd)) == -1 || + (tmp2 = dup(pmonitor->m_recvfd)) == -1) { + error("%s: cannot allocate fds for pty", __func__); + if (tmp1 > 0) + close(tmp1); + if (tmp2 > 0) + close(tmp2); + return 0; + } + close(tmp1); + close(tmp2); buffer_init(&m); mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTY, &m); @@ -711,8 +724,9 @@ mm_session_pty_cleanup2(Session *s) buffer_free(&m); /* closed dup'ed master */ - if (close(s->ptymaster) < 0) - error("close(s->ptymaster): %s", strerror(errno)); + if (s->ptymaster != -1 && close(s->ptymaster) < 0) + error("close(s->ptymaster/%d): %s", + s->ptymaster, strerror(errno)); /* unlink pty from session */ s->ttyfd = -1; @@ -1,4 +1,4 @@ -/* $OpenBSD: servconf.c,v 1.179 2008/05/08 12:02:23 djm Exp $ */ +/* $OpenBSD: servconf.c,v 1.180 2008/05/08 12:21:16 djm Exp $ */ /* * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * All rights reserved @@ -114,6 +114,7 @@ initialize_server_options(ServerOptions *options) options->max_startups_rate = -1; options->max_startups = -1; options->max_authtries = -1; + options->max_sessions = -1; options->banner = NULL; options->use_dns = -1; options->client_alive_interval = -1; @@ -237,6 +238,8 @@ fill_default_server_options(ServerOptions *options) options->max_startups_begin = options->max_startups; if (options->max_authtries == -1) options->max_authtries = DEFAULT_AUTH_FAIL_MAX; + if (options->max_sessions == -1) + options->max_sessions = DEFAULT_SESSIONS_MAX; if (options->use_dns == -1) options->use_dns = 1; if (options->client_alive_interval == -1) @@ -291,7 +294,7 @@ typedef enum { sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups, sIgnoreUserKnownHosts, sCiphers, sMacs, sProtocol, sPidFile, sGatewayPorts, sPubkeyAuthentication, sXAuthLocation, sSubsystem, - sMaxStartups, sMaxAuthTries, + sMaxStartups, sMaxAuthTries, sMaxSessions, sBanner, sUseDNS, sHostbasedAuthentication, sHostbasedUsesNameFromPacketOnly, sClientAliveInterval, sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2, @@ -395,6 +398,7 @@ static struct { { "subsystem", sSubsystem, SSHCFG_GLOBAL }, { "maxstartups", sMaxStartups, SSHCFG_GLOBAL }, { "maxauthtries", sMaxAuthTries, SSHCFG_GLOBAL }, + { "maxsessions", sMaxSessions, SSHCFG_ALL }, { "banner", sBanner, SSHCFG_ALL }, { "usedns", sUseDNS, SSHCFG_GLOBAL }, { "verifyreversemapping", sDeprecated, SSHCFG_GLOBAL }, @@ -695,7 +699,7 @@ process_server_config_line(ServerOptions *options, char *line, case sServerKeyBits: intptr = &options->server_key_bits; -parse_int: + parse_int: arg = strdelim(&cp); if (!arg || *arg == '\0') fatal("%s line %d: missing integer value.", @@ -707,7 +711,7 @@ parse_int: case sLoginGraceTime: intptr = &options->login_grace_time; -parse_time: + parse_time: arg = strdelim(&cp); if (!arg || *arg == '\0') fatal("%s line %d: missing time value.", @@ -776,7 +780,7 @@ parse_time: fatal("%s line %d: too many host keys specified (max %d).", filename, linenum, MAX_HOSTKEYS); charptr = &options->host_key_files[*intptr]; -parse_filename: + parse_filename: arg = strdelim(&cp); if (!arg || *arg == '\0') fatal("%s line %d: missing file name.", @@ -819,7 +823,7 @@ parse_filename: case sIgnoreRhosts: intptr = &options->ignore_rhosts; -parse_flag: + parse_flag: arg = strdelim(&cp); if (!arg || *arg == '\0') fatal("%s line %d: missing yes/no argument.", @@ -1155,6 +1159,10 @@ parse_flag: intptr = &options->max_authtries; goto parse_int; + case sMaxSessions: + intptr = &options->max_sessions; + goto parse_int; + case sBanner: charptr = &options->banner; goto parse_filename; @@ -1382,6 +1390,7 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth) M_CP_INTOPT(x11_display_offset); M_CP_INTOPT(x11_forwarding); M_CP_INTOPT(x11_use_localhost); + M_CP_INTOPT(max_sessions); M_CP_STROPT(banner); if (preauth) @@ -1,4 +1,4 @@ -/* $OpenBSD: servconf.h,v 1.83 2008/05/07 05:49:37 pyr Exp $ */ +/* $OpenBSD: servconf.h,v 1.84 2008/05/08 12:21:16 djm Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> @@ -35,6 +35,7 @@ #define PERMIT_YES 3 #define DEFAULT_AUTH_FAIL_MAX 6 /* Default for MaxAuthTries */ +#define DEFAULT_SESSIONS_MAX 10 /* Default for MaxSessions */ /* Magic name for internal sftp-server */ #define INTERNAL_SFTP_NAME "internal-sftp" @@ -123,6 +124,7 @@ typedef struct { int max_startups_rate; int max_startups; int max_authtries; + int max_sessions; char *banner; /* SSH-2 banner message */ int use_dns; int client_alive_interval; /* @@ -1,4 +1,4 @@ -/* $OpenBSD: session.c,v 1.236 2008/05/08 12:02:23 djm Exp $ */ +/* $OpenBSD: session.c,v 1.237 2008/05/08 12:21:16 djm Exp $ */ /* * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland * All rights reserved @@ -102,9 +102,9 @@ void session_set_fds(Session *, int, int, int); void session_pty_cleanup(Session *); 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 *); +int do_exec_pty(Session *, const char *); +int do_exec_no_pty(Session *, const char *); +int do_exec(Session *, const char *); void do_login(Session *, const char *); #ifdef LOGIN_NEEDS_UTMPX static void do_pre_login(Session *s); @@ -132,8 +132,9 @@ extern Buffer loginmsg; const char *original_command = NULL; /* data */ -#define MAX_SESSIONS 20 -Session sessions[MAX_SESSIONS]; +static int sessions_first_unused = -1; +static int sessions_nalloc = 0; +static Session *sessions = NULL; #define SUBSYSTEM_NONE 0 #define SUBSYSTEM_EXT 1 @@ -167,7 +168,7 @@ static int auth_input_request_forwarding(struct passwd * pw) { Channel *nc; - int sock; + int sock = -1; struct sockaddr_un sunaddr; if (auth_sock_name != NULL) { @@ -179,43 +180,48 @@ auth_input_request_forwarding(struct passwd * pw) 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-XXXXXXXXXX", MAXPATHLEN); + auth_sock_dir = xstrdup("/tmp/ssh-XXXXXXXXXX"); /* 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; + goto authsock_err; } - snprintf(auth_sock_name, MAXPATHLEN, "%s/agent.%ld", - auth_sock_dir, (long) getpid()); + + xasprintf(&auth_sock_name, "%s/agent.%ld", + auth_sock_dir, (long) getpid()); /* Create the socket. */ sock = socket(AF_UNIX, SOCK_STREAM, 0); - if (sock < 0) - packet_disconnect("socket: %.100s", strerror(errno)); + if (sock < 0) { + error("socket: %.100s", strerror(errno)); + restore_uid(); + goto authsock_err; + } /* 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)); + if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) { + error("bind: %.100s", strerror(errno)); + restore_uid(); + goto authsock_err; + } /* Restore the privileged uid. */ restore_uid(); /* Start listening on the socket. */ - if (listen(sock, SSH_LISTEN_BACKLOG) < 0) - packet_disconnect("listen: %.100s", strerror(errno)); + if (listen(sock, SSH_LISTEN_BACKLOG) < 0) { + error("listen: %.100s", strerror(errno)); + goto authsock_err; + } /* Allocate a channel for the authentication agent socket. */ nc = channel_new("auth socket", @@ -224,6 +230,19 @@ auth_input_request_forwarding(struct passwd * pw) 0, "auth socket", 1); strlcpy(nc->path, auth_sock_name, sizeof(nc->path)); return 1; + + authsock_err: + if (auth_sock_name != NULL) + xfree(auth_sock_name); + if (auth_sock_dir != NULL) { + rmdir(auth_sock_dir); + xfree(auth_sock_dir); + } + if (sock != -1) + close(sock); + auth_sock_name = NULL; + auth_sock_dir = NULL; + return 0; } static void @@ -373,10 +392,14 @@ do_authenticated1(Authctxt *authctxt) if (type == SSH_CMSG_EXEC_CMD) { command = packet_get_string(&dlen); debug("Exec command '%.500s'", command); - do_exec(s, command); + if (do_exec(s, command) != 0) + packet_disconnect( + "command execution failed"); xfree(command); } else { - do_exec(s, NULL); + if (do_exec(s, NULL) != 0) + packet_disconnect( + "shell execution failed"); } packet_check_eom(); session_close(s); @@ -401,41 +424,84 @@ do_authenticated1(Authctxt *authctxt) } } +#define USE_PIPES /* * 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 +int do_exec_no_pty(Session *s, const char *command) { pid_t pid; #ifdef USE_PIPES int pin[2], pout[2], perr[2]; + /* Allocate pipes for communicating with the program. */ - if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0) - packet_disconnect("Could not create pipes: %.100s", - strerror(errno)); -#else /* USE_PIPES */ + if (pipe(pin) < 0) { + error("%s: pipe in: %.100s", __func__, strerror(errno)); + return -1; + } + if (pipe(pout) < 0) { + error("%s: pipe out: %.100s", __func__, strerror(errno)); + close(pin[0]); + close(pin[1]); + return -1; + } + if (pipe(perr) < 0) { + error("%s: pipe err: %.100s", __func__, strerror(errno)); + close(pin[0]); + close(pin[1]); + close(pout[0]); + close(pout[1]); + return -1; + } +#else 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 (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0) { + error("%s: socketpair #1: %.100s", __func__, strerror(errno)); + return -1; + } + if (socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0) { + error("%s: socketpair #2: %.100s", __func__, strerror(errno)); + close(inout[0]); + close(inout[1]); + return -1; + } +#endif + if (s == NULL) fatal("do_exec_no_pty: no session"); session_proctitle(s); /* Fork the child. */ - if ((pid = fork()) == 0) { + switch ((pid = fork())) { + case -1: + error("%s: fork: %.100s", __func__, strerror(errno)); +#ifdef USE_PIPES + close(pin[0]); + close(pin[1]); + close(pout[0]); + close(pout[1]); + close(perr[0]); + close(perr[1]); +#else + close(inout[0]); + close(inout[1]); + close(err[0]); + close(err[1]); +#endif + return -1; + case 0: is_child = 1; /* Child. Reinitialize the log since the pid has changed. */ - log_init(__progname, options.log_level, options.log_facility, log_stderr); + log_init(__progname, options.log_level, + options.log_facility, log_stderr); /* * Create a new session and process group since the 4.4BSD @@ -465,7 +531,7 @@ do_exec_no_pty(Session *s, const char *command) if (dup2(perr[1], 2) < 0) perror("dup2 stderr"); close(perr[1]); -#else /* USE_PIPES */ +#else /* * Redirect stdin, stdout, and stderr. Stdin and stdout will * use the same socket, as some programs (particularly rdist) @@ -475,11 +541,14 @@ do_exec_no_pty(Session *s, const char *command) 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. */ + if (dup2(inout[0], 1) < 0) /* stdout (same as stdin) */ perror("dup2 stdout"); + close(inout[0]); if (dup2(err[0], 2) < 0) /* stderr */ perror("dup2 stderr"); -#endif /* USE_PIPES */ + close(err[0]); +#endif + #ifdef _UNICOS cray_init_job(s->pw); /* set up cray jid and tmpdir */ @@ -488,7 +557,10 @@ do_exec_no_pty(Session *s, const char *command) /* Do processing for the child (exec command etc). */ do_child(s, command); /* NOTREACHED */ + default: + break; } + #ifdef _UNICOS signal(WJSIGNAL, cray_job_termination_handler); #endif /* _UNICOS */ @@ -496,11 +568,18 @@ do_exec_no_pty(Session *s, const char *command) 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); + + /* + * Clear loginmsg, since it's the child's responsibility to display + * it to the user, otherwise multiple sessions may accumulate + * multiple copies of the login messages. + */ + buffer_clear(&loginmsg); + #ifdef USE_PIPES /* We are the parent. Close the child sides of the pipes. */ close(pin[0]); @@ -518,29 +597,26 @@ do_exec_no_pty(Session *s, const char *command) server_loop(pid, pin[1], pout[0], perr[0]); /* server_loop has closed pin[1], pout[0], and perr[0]. */ } -#else /* USE_PIPES */ +#else /* We are the parent. Close the child sides of the socket pairs. */ close(inout[0]); close(err[0]); /* - * Clear loginmsg, since it's the child's responsibility to display - * it to the user, otherwise multiple sessions may accumulate - * multiple copies of the login messages. - */ - buffer_clear(&loginmsg); - - /* * 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]); + session_set_fds(s, inout[1], inout[1], + s->is_subsystem ? -1 : err[1]); + if (s->is_subsystem) + close(err[1]); } else { server_loop(pid, inout[1], inout[1], err[1]); /* server_loop has closed inout[1] and err[1]. */ } -#endif /* USE_PIPES */ +#endif + return 0; } /* @@ -549,7 +625,7 @@ do_exec_no_pty(Session *s, const char *command) * setting up file descriptors, controlling tty, updating wtmp, utmp, * lastlog, and other such operations. */ -void +int do_exec_pty(Session *s, const char *command) { int fdout, ptyfd, ttyfd, ptymaster; @@ -560,12 +636,46 @@ do_exec_pty(Session *s, const char *command) ptyfd = s->ptyfd; ttyfd = s->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. + * Do this before forking (and cleanup in the child) so as to + * detect and gracefully fail out-of-fd conditions. + */ + if ((fdout = dup(ptyfd)) < 0) { + error("%s: dup #1: %s", __func__, strerror(errno)); + close(ttyfd); + close(ptyfd); + return -1; + } + /* we keep a reference to the pty master */ + if ((ptymaster = dup(ptyfd)) < 0) { + error("%s: dup #2: %s", __func__, strerror(errno)); + close(ttyfd); + close(ptyfd); + close(fdout); + return -1; + } + /* Fork the child. */ - if ((pid = fork()) == 0) { + switch ((pid = fork())) { + case -1: + error("%s: fork: %.100s", __func__, strerror(errno)); + close(fdout); + close(ptymaster); + close(ttyfd); + close(ptyfd); + return -1; + case 0: is_child = 1; + close(fdout); + close(ptymaster); + /* Child. Reinitialize the log because the pid has changed. */ - log_init(__progname, options.log_level, options.log_facility, log_stderr); + log_init(__progname, options.log_level, + options.log_facility, log_stderr); /* Close the master side of the pseudo tty. */ close(ptyfd); @@ -596,11 +706,16 @@ do_exec_pty(Session *s, const char *command) do_pre_login(s); # endif #endif - - /* Do common processing for the child, such as execing the command. */ - do_child(s, command); - /* NOTREACHED */ + /* + * Do common processing for the child, such as execing + * the command. + */ + do_child(s, command); + /* NOTREACHED */ + default: + break; } + #ifdef _UNICOS signal(WJSIGNAL, cray_job_termination_handler); #endif /* _UNICOS */ @@ -608,29 +723,14 @@ do_exec_pty(Session *s, const char *command) 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. */ + s->ptymaster = ptymaster; packet_set_interactive(1); if (compat20) { session_set_fds(s, ptyfd, fdout, -1); @@ -638,6 +738,7 @@ do_exec_pty(Session *s, const char *command) server_loop(pid, ptyfd, fdout, -1); /* server_loop _has_ closed ptyfd and fdout. */ } + return 0; } #ifdef LOGIN_NEEDS_UTMPX @@ -672,9 +773,11 @@ do_pre_login(Session *s) * This is called to fork and execute a command. If another command is * to be forced, execute that instead. */ -void +int do_exec(Session *s, const char *command) { + int ret; + if (options.adm_forced_command) { original_command = command; command = options.adm_forced_command; @@ -705,9 +808,9 @@ do_exec(Session *s, const char *command) } #endif if (s->ttyfd != -1) - do_exec_pty(s, command); + ret = do_exec_pty(s, command); else - do_exec_no_pty(s, command); + ret = do_exec_no_pty(s, command); original_command = NULL; @@ -717,6 +820,8 @@ do_exec(Session *s, const char *command) * multiple copies of the login messages. */ buffer_clear(&loginmsg); + + return ret; } /* administrative, login(1)-like work */ @@ -1740,43 +1845,79 @@ do_child(Session *s, const char *command) exit(1); } +void +session_unused(int id) +{ + debug3("%s: session id %d unused", __func__, id); + if (id >= options.max_sessions || + id >= sessions_nalloc) { + fatal("%s: insane session id %d (max %d nalloc %d)", + __func__, id, options.max_sessions, sessions_nalloc); + } + bzero(&sessions[id], sizeof(*sessions)); + sessions[id].self = id; + sessions[id].used = 0; + sessions[id].chanid = -1; + sessions[id].ptyfd = -1; + sessions[id].ttyfd = -1; + sessions[id].ptymaster = -1; + sessions[id].x11_chanids = NULL; + sessions[id].next_unused = sessions_first_unused; + sessions_first_unused = id; +} + 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; + Session *s, *tmp; + + if (sessions_first_unused == -1) { + if (sessions_nalloc >= options.max_sessions) + return NULL; + debug2("%s: allocate (allocated %d max %d)", + __func__, sessions_nalloc, options.max_sessions); + tmp = xrealloc(sessions, sessions_nalloc + 1, + sizeof(*sessions)); + if (tmp == NULL) { + error("%s: cannot allocate %d sessions", + __func__, sessions_nalloc + 1); + return NULL; } - did_init = 1; + sessions = tmp; + session_unused(sessions_nalloc++); } - 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->x11_chanids = NULL; - debug("session_new: session %d", i); - return s; - } + + if (sessions_first_unused >= sessions_nalloc || + sessions_first_unused < 0) { + fatal("%s: insane first_unused %d max %d nalloc %d", + __func__, sessions_first_unused, options.max_sessions, + sessions_nalloc); } - return NULL; + + s = &sessions[sessions_first_unused]; + if (s->used) { + fatal("%s: session %d already used", + __func__, sessions_first_unused); + } + sessions_first_unused = s->next_unused; + s->used = 1; + s->next_unused = -1; + debug("session_new: session %d", s->self); + + return s; } static void session_dump(void) { int i; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; - debug("dump: used %d session %d %p channel %d pid %ld", + + debug("dump: used %d next_unused %d session %d %p " + "channel %d pid %ld", s->used, + s->next_unused, s->self, s, s->chanid, @@ -1806,7 +1947,7 @@ Session * session_by_tty(char *tty) { int i; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; 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); @@ -1822,10 +1963,11 @@ static Session * session_by_channel(int id) { int i; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; if (s->used && s->chanid == id) { - debug("session_by_channel: session %d channel %d", i, id); + debug("session_by_channel: session %d channel %d", + i, id); return s; } } @@ -1839,7 +1981,7 @@ session_by_x11_channel(int id) { int i, j; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; if (s->x11_chanids == NULL || !s->used) @@ -1862,7 +2004,7 @@ session_by_pid(pid_t pid) { int i; debug("session_by_pid: pid %ld", (long)pid); - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; if (s->used && s->pid == pid) return s; @@ -1918,7 +2060,8 @@ session_pty_req(Session *s) /* Allocate a pty and open it. */ debug("Allocating pty."); - if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)))) { + if (!PRIVSEP(pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, + sizeof(s->tty)))) { if (s->term) xfree(s->term); s->term = NULL; @@ -1971,8 +2114,7 @@ session_subsystem_req(Session *s) s->is_subsystem = SUBSYSTEM_EXT; } debug("subsystem: exec() %s", cmd); - do_exec(s, cmd); - success = 1; + success = do_exec(s, cmd) == 0; break; } } @@ -2015,19 +2157,19 @@ static int session_shell_req(Session *s) { packet_check_eom(); - do_exec(s, NULL); - return 1; + return do_exec(s, NULL) == 0; } static int session_exec_req(Session *s) { - u_int len; + u_int len, success; + char *command = packet_get_string(&len); packet_check_eom(); - do_exec(s, command); + success = do_exec(s, command) == 0; xfree(command); - return 1; + return success; } static int @@ -2037,8 +2179,7 @@ session_break_req(Session *s) packet_get_int(); /* ignored */ packet_check_eom(); - if (s->ttyfd == -1 || - tcsendbreak(s->ttyfd, 0) < 0) + if (s->ttyfd == -1 || tcsendbreak(s->ttyfd, 0) < 0) return 0; return 1; } @@ -2185,8 +2326,9 @@ session_pty_cleanup2(Session *s) * 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)); + if (s->ptymaster != -1 && close(s->ptymaster) < 0) + error("close(s->ptymaster/%d): %s", + s->ptymaster, strerror(errno)); /* unlink pty from session */ s->ttyfd = -1; @@ -2346,7 +2488,6 @@ session_close(Session *s) xfree(s->auth_data); if (s->auth_proto) xfree(s->auth_proto); - s->used = 0; if (s->env != NULL) { for (i = 0; i < s->num_env; i++) { xfree(s->env[i].name); @@ -2355,6 +2496,7 @@ session_close(Session *s) xfree(s->env); } session_proctitle(s); + session_unused(s->self); } void @@ -2418,7 +2560,7 @@ void session_destroy_all(void (*closefunc)(Session *)) { int i; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; if (s->used) { if (closefunc != NULL) @@ -2437,7 +2579,7 @@ session_tty_list(void) char *cp; buf[0] = '\0'; - for (i = 0; i < MAX_SESSIONS; i++) { + for (i = 0; i < sessions_nalloc; i++) { Session *s = &sessions[i]; if (s->used && s->ttyfd != -1) { @@ -1,4 +1,4 @@ -/* $OpenBSD: session.h,v 1.29 2006/08/03 03:34:42 deraadt Exp $ */ +/* $OpenBSD: session.h,v 1.30 2008/05/08 12:21:16 djm Exp $ */ /* * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. @@ -31,6 +31,7 @@ typedef struct Session Session; struct Session { int used; int self; + int next_unused; struct passwd *pw; Authctxt *authctxt; pid_t pid; @@ -65,6 +66,7 @@ void do_authenticated(Authctxt *); void do_cleanup(Authctxt *); int session_open(Authctxt *, int); +void session_unused(int); int session_input_channel_req(Channel *, const char *); void session_close_by_pid(pid_t, int); void session_close_by_channel(int, void *); diff --git a/sshd_config b/sshd_config index 1f97a9dc..c5ee7c8a 100644 --- a/sshd_config +++ b/sshd_config @@ -1,4 +1,4 @@ -# $OpenBSD: sshd_config,v 1.78 2008/05/07 06:43:35 pyr Exp $ +# $OpenBSD: sshd_config,v 1.79 2008/05/08 12:21:16 djm Exp $ # This is the sshd server system-wide configuration file. See # sshd_config(5) for more information. @@ -41,6 +41,7 @@ Protocol 2 #PermitRootLogin yes #StrictModes yes #MaxAuthTries 6 +#MaxSessions 10 #RSAAuthentication yes #PubkeyAuthentication yes diff --git a/sshd_config.5 b/sshd_config.5 index 99b5621e..0d8c140b 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -34,8 +34,8 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.\" $OpenBSD: sshd_config.5,v 1.89 2008/05/07 08:00:14 jmc Exp $ -.Dd $Mdocdate: May 19 2008 $ +.\" $OpenBSD: sshd_config.5,v 1.90 2008/05/08 12:21:16 djm Exp $ +.Dd $Mdocdate: May 8 2008 $ .Dt SSHD_CONFIG 5 .Os .Sh NAME @@ -594,6 +594,9 @@ connection. Once the number of failures reaches half this value, additional failures are logged. The default is 6. +.It Cm MaxSessions +Specifies the maximum number of open sessions permitted per network connection. +The default is 10. .It Cm MaxStartups Specifies the maximum number of concurrent unauthenticated connections to the SSH daemon. |