From e07335e2b6b82e8af62ee5f4e917e2f9e93b9ed9 Mon Sep 17 00:00:00 2001 From: djm Date: Fri, 18 Aug 2006 14:31:39 +0000 Subject: [PATCH] - djm@cvs.openbsd.org 2006/08/16 11:47:15 [sshd.c] factor inetd connection, TCP listen and main TCP accept loop out of main() into separate functions to improve readability; ok markus@ --- ChangeLog | 4 + sshd.c | 637 ++++++++++++++++++++++++++++-------------------------- 2 files changed, 336 insertions(+), 305 deletions(-) diff --git a/ChangeLog b/ChangeLog index 3aa83057..9fa65236 100644 --- a/ChangeLog +++ b/ChangeLog @@ -18,6 +18,10 @@ [servconf.c servconf.h sshd_config.5] Add ability to match groups to Match keyword in sshd_config. Feedback djm@, stevesk@, ok stevesk@. + - djm@cvs.openbsd.org 2006/08/16 11:47:15 + [sshd.c] + factor inetd connection, TCP listen and main TCP accept loop out of + main() into separate functions to improve readability; ok markus@ 20060817 - (dtucker) [openbsd-compat/fake-rfc2553.c openbsd-compat/setproctitle.c] diff --git a/sshd.c b/sshd.c index ca418e36..7065d471 100644 --- a/sshd.c +++ b/sshd.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshd.c,v 1.344 2006/08/05 07:52:52 dtucker Exp $ */ +/* $OpenBSD: sshd.c,v 1.345 2006/08/16 11:47:15 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -905,6 +905,322 @@ recv_rexec_state(int fd, Buffer *conf) debug3("%s: done", __func__); } +/* Accept a connection from inetd */ +static void +server_accept_inetd(int *sock_in, int *sock_out) +{ + int fd; + + startup_pipe = -1; + if (rexeced_flag) { + close(REEXEC_CONFIG_PASS_FD); + *sock_in = *sock_out = dup(STDIN_FILENO); + if (!debug_flag) { + startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); + close(REEXEC_STARTUP_PIPE_FD); + } + } else { + *sock_in = dup(STDIN_FILENO); + *sock_out = dup(STDOUT_FILENO); + } + /* + * We intentionally do not close the descriptors 0, 1, and 2 + * as our code for setting the descriptors won't work if + * ttyfd happens to be one of those. + */ + if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { + dup2(fd, STDIN_FILENO); + dup2(fd, STDOUT_FILENO); + if (fd > STDOUT_FILENO) + close(fd); + } + debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); +} + +/* + * Listen for TCP connections + */ +static void +server_listen(void) +{ + int ret, listen_sock, on = 1; + struct addrinfo *ai; + char ntop[NI_MAXHOST], strport[NI_MAXSERV]; + + for (ai = options.listen_addrs; ai; ai = ai->ai_next) { + if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) + continue; + if (num_listen_socks >= MAX_LISTEN_SOCKS) + fatal("Too many listen sockets. " + "Enlarge MAX_LISTEN_SOCKS"); + if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, + ntop, sizeof(ntop), strport, sizeof(strport), + NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { + error("getnameinfo failed: %.100s", + (ret != EAI_SYSTEM) ? gai_strerror(ret) : + strerror(errno)); + continue; + } + /* Create socket for listening. */ + listen_sock = socket(ai->ai_family, ai->ai_socktype, + ai->ai_protocol); + if (listen_sock < 0) { + /* kernel may not support ipv6 */ + verbose("socket: %.100s", strerror(errno)); + continue; + } + if (set_nonblock(listen_sock) == -1) { + close(listen_sock); + continue; + } + /* + * Set socket options. + * Allow local port reuse in TIME_WAIT. + */ + if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, + &on, sizeof(on)) == -1) + error("setsockopt SO_REUSEADDR: %s", strerror(errno)); + + debug("Bind to port %s on %s.", strport, ntop); + + /* Bind the socket to the desired port. */ + if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { + error("Bind to port %s on %s failed: %.200s.", + strport, ntop, strerror(errno)); + close(listen_sock); + continue; + } + listen_socks[num_listen_socks] = listen_sock; + num_listen_socks++; + + /* Start listening on the port. */ + if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) + fatal("listen on [%s]:%s: %.100s", + ntop, strport, strerror(errno)); + logit("Server listening on %s port %s.", ntop, strport); + } + freeaddrinfo(options.listen_addrs); + + if (!num_listen_socks) + fatal("Cannot bind any address."); +} + +/* + * The main TCP accept loop. Note that, for the non-debug case, returns + * from this function are in a forked subprocess. + */ +static void +server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) +{ + fd_set *fdset; + int i, j, ret, maxfd; + int key_used = 0, startups = 0; + int startup_p[2] = { -1 , -1 }; + struct sockaddr_storage from; + socklen_t fromlen; + pid_t pid; + + /* setup fd set for accept */ + fdset = NULL; + maxfd = 0; + for (i = 0; i < num_listen_socks; i++) + if (listen_socks[i] > maxfd) + maxfd = listen_socks[i]; + /* pipes connected to unauthenticated childs */ + startup_pipes = xcalloc(options.max_startups, sizeof(int)); + for (i = 0; i < options.max_startups; i++) + startup_pipes[i] = -1; + + /* + * Stay listening for connections until the system crashes or + * the daemon is killed with a signal. + */ + for (;;) { + if (received_sighup) + sighup_restart(); + if (fdset != NULL) + xfree(fdset); + fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), + sizeof(fd_mask)); + + for (i = 0; i < num_listen_socks; i++) + FD_SET(listen_socks[i], fdset); + for (i = 0; i < options.max_startups; i++) + if (startup_pipes[i] != -1) + FD_SET(startup_pipes[i], fdset); + + /* Wait in select until there is a connection. */ + ret = select(maxfd+1, fdset, NULL, NULL, NULL); + if (ret < 0 && errno != EINTR) + error("select: %.100s", strerror(errno)); + if (received_sigterm) { + logit("Received signal %d; terminating.", + (int) received_sigterm); + close_listen_socks(); + unlink(options.pid_file); + exit(255); + } + if (key_used && key_do_regen) { + generate_ephemeral_server_key(); + key_used = 0; + key_do_regen = 0; + } + if (ret < 0) + continue; + + for (i = 0; i < options.max_startups; i++) + if (startup_pipes[i] != -1 && + FD_ISSET(startup_pipes[i], fdset)) { + /* + * the read end of the pipe is ready + * if the child has closed the pipe + * after successful authentication + * or if the child has died + */ + close(startup_pipes[i]); + startup_pipes[i] = -1; + startups--; + } + for (i = 0; i < num_listen_socks; i++) { + if (!FD_ISSET(listen_socks[i], fdset)) + continue; + fromlen = sizeof(from); + *newsock = accept(listen_socks[i], + (struct sockaddr *)&from, &fromlen); + if (*newsock < 0) { + if (errno != EINTR && errno != EWOULDBLOCK) + error("accept: %.100s", strerror(errno)); + continue; + } + if (unset_nonblock(*newsock) == -1) { + close(*newsock); + continue; + } + if (drop_connection(startups) == 1) { + debug("drop connection #%d", startups); + close(*newsock); + continue; + } + if (pipe(startup_p) == -1) { + close(*newsock); + continue; + } + + if (rexec_flag && socketpair(AF_UNIX, + SOCK_STREAM, 0, config_s) == -1) { + error("reexec socketpair: %s", + strerror(errno)); + close(*newsock); + close(startup_p[0]); + close(startup_p[1]); + continue; + } + + for (j = 0; j < options.max_startups; j++) + if (startup_pipes[j] == -1) { + startup_pipes[j] = startup_p[0]; + if (maxfd < startup_p[0]) + maxfd = startup_p[0]; + startups++; + break; + } + + /* + * Got connection. Fork a child to handle it, unless + * we are in debugging mode. + */ + if (debug_flag) { + /* + * In debugging mode. Close the listening + * socket, and start processing the + * connection without forking. + */ + debug("Server will not fork when running in debugging mode."); + close_listen_socks(); + *sock_in = *newsock; + *sock_out = *newsock; + close(startup_p[0]); + close(startup_p[1]); + startup_pipe = -1; + pid = getpid(); + if (rexec_flag) { + send_rexec_state(config_s[0], + &cfg); + close(config_s[0]); + } + break; + } + + /* + * Normal production daemon. Fork, and have + * the child process the connection. The + * parent continues listening. + */ + if ((pid = fork()) == 0) { + /* + * Child. Close the listening and + * max_startup sockets. Start using + * the accepted socket. Reinitialize + * logging (since our pid has changed). + * We break out of the loop to handle + * the connection. + */ + startup_pipe = startup_p[1]; + close_startup_pipes(); + close_listen_socks(); + *sock_in = *newsock; + *sock_out = *newsock; + log_init(__progname, + options.log_level, + options.log_facility, + log_stderr); + if (rexec_flag) + close(config_s[0]); + break; + } + + /* Parent. Stay in the loop. */ + if (pid < 0) + error("fork: %.100s", strerror(errno)); + else + debug("Forked child %ld.", (long)pid); + + close(startup_p[1]); + + if (rexec_flag) { + send_rexec_state(config_s[0], &cfg); + close(config_s[0]); + close(config_s[1]); + } + + /* + * Mark that the key has been used (it + * was "given" to the child). + */ + if ((options.protocol & SSH_PROTO_1) && + key_used == 0) { + /* Schedule server key regeneration alarm. */ + signal(SIGALRM, key_regeneration_alarm); + alarm(options.key_regeneration_time); + key_used = 1; + } + + close(*newsock); + + /* + * Ensure that our random state differs + * from that of the child + */ + arc4random_stir(); + } + + /* child process check (or debug mode) */ + if (num_listen_socks < 0) + break; + } +} + + /* * Main program for the daemon. */ @@ -913,24 +1229,14 @@ main(int ac, char **av) { extern char *optarg; extern int optind; - int opt, j, i, on = 1; + int opt, i, on = 1; int sock_in = -1, sock_out = -1, newsock = -1; - pid_t pid; - socklen_t fromlen; - fd_set *fdset; - struct sockaddr_storage from; const char *remote_ip; int remote_port; - FILE *f; - struct addrinfo *ai; - char ntop[NI_MAXHOST], strport[NI_MAXSERV]; char *line; - int listen_sock, maxfd; - int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 }; - int startups = 0; + int config_s[2] = { -1 , -1 }; Key *key; Authctxt *authctxt; - int ret, key_used = 0; #ifdef HAVE_SECUREWARE (void)set_auth_parameters(ac, av); @@ -1278,121 +1584,31 @@ main(int ac, char **av) /* ignore SIGPIPE */ signal(SIGPIPE, SIG_IGN); - /* Start listening for a socket, unless started from inetd. */ + /* Get a connection, either from inetd or a listening TCP socket */ if (inetd_flag) { - int fd; + server_accept_inetd(&sock_in, &sock_out); - startup_pipe = -1; - if (rexeced_flag) { - close(REEXEC_CONFIG_PASS_FD); - sock_in = sock_out = dup(STDIN_FILENO); - if (!debug_flag) { - startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); - close(REEXEC_STARTUP_PIPE_FD); - } - } else { - sock_in = dup(STDIN_FILENO); - sock_out = dup(STDOUT_FILENO); - } - /* - * We intentionally do not close the descriptors 0, 1, and 2 - * as our code for setting the descriptors won't work if - * ttyfd happens to be one of those. - */ - if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { - dup2(fd, STDIN_FILENO); - dup2(fd, STDOUT_FILENO); - if (fd > STDOUT_FILENO) - close(fd); - } - debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); if ((options.protocol & SSH_PROTO_1) && sensitive_data.server_key == NULL) generate_ephemeral_server_key(); } else { - for (ai = options.listen_addrs; ai; ai = ai->ai_next) { - if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) - continue; - if (num_listen_socks >= MAX_LISTEN_SOCKS) - fatal("Too many listen sockets. " - "Enlarge MAX_LISTEN_SOCKS"); - if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, - ntop, sizeof(ntop), strport, sizeof(strport), - NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { - error("getnameinfo failed: %.100s", - (ret != EAI_SYSTEM) ? gai_strerror(ret) : - strerror(errno)); - continue; - } - /* Create socket for listening. */ - listen_sock = socket(ai->ai_family, ai->ai_socktype, - ai->ai_protocol); - if (listen_sock < 0) { - /* kernel may not support ipv6 */ - verbose("socket: %.100s", strerror(errno)); - continue; - } - if (set_nonblock(listen_sock) == -1) { - close(listen_sock); - continue; - } - /* - * Set socket options. - * Allow local port reuse in TIME_WAIT. - */ - if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, - &on, sizeof(on)) == -1) - error("setsockopt SO_REUSEADDR: %s", strerror(errno)); - - debug("Bind to port %s on %s.", strport, ntop); - - /* Bind the socket to the desired port. */ - if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { - if (!ai->ai_next) - error("Bind to port %s on %s failed: %.200s.", - strport, ntop, strerror(errno)); - close(listen_sock); - continue; - } - listen_socks[num_listen_socks] = listen_sock; - num_listen_socks++; - - /* Start listening on the port. */ - if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) - fatal("listen on [%s]:%s: %.100s", - ntop, strport, strerror(errno)); - logit("Server listening on %s port %s.", ntop, strport); - } - freeaddrinfo(options.listen_addrs); - - if (!num_listen_socks) - fatal("Cannot bind any address."); + server_listen(); if (options.protocol & SSH_PROTO_1) generate_ephemeral_server_key(); - /* - * Arrange to restart on SIGHUP. The handler needs - * listen_sock. - */ signal(SIGHUP, sighup_handler); - + signal(SIGCHLD, main_sigchld_handler); signal(SIGTERM, sigterm_handler); signal(SIGQUIT, sigterm_handler); - /* Arrange SIGCHLD to be caught. */ - signal(SIGCHLD, main_sigchld_handler); - - /* Write out the pid file after the sigterm handler is setup */ + /* + * Write out the pid file after the sigterm handler + * is setup and the listen sockets are bound + */ if (!debug_flag) { - /* - * Record our pid in /var/run/sshd.pid to make it - * easier to kill the correct sshd. We don't want to - * do this before the bind above because the bind will - * fail if there already is a daemon, and this will - * overwrite any old pid in the file. - */ - f = fopen(options.pid_file, "wb"); + FILE *f = fopen(options.pid_file, "w"); + if (f == NULL) { error("Couldn't create pid file \"%s\": %s", options.pid_file, strerror(errno)); @@ -1402,198 +1618,9 @@ main(int ac, char **av) } } - /* setup fd set for listen */ - fdset = NULL; - maxfd = 0; - for (i = 0; i < num_listen_socks; i++) - if (listen_socks[i] > maxfd) - maxfd = listen_socks[i]; - /* pipes connected to unauthenticated childs */ - startup_pipes = xcalloc(options.max_startups, sizeof(int)); - for (i = 0; i < options.max_startups; i++) - startup_pipes[i] = -1; - - /* - * Stay listening for connections until the system crashes or - * the daemon is killed with a signal. - */ - for (;;) { - if (received_sighup) - sighup_restart(); - if (fdset != NULL) - xfree(fdset); - fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), - sizeof(fd_mask)); - - for (i = 0; i < num_listen_socks; i++) - FD_SET(listen_socks[i], fdset); - for (i = 0; i < options.max_startups; i++) - if (startup_pipes[i] != -1) - FD_SET(startup_pipes[i], fdset); - - /* Wait in select until there is a connection. */ - ret = select(maxfd+1, fdset, NULL, NULL, NULL); - if (ret < 0 && errno != EINTR) - error("select: %.100s", strerror(errno)); - if (received_sigterm) { - logit("Received signal %d; terminating.", - (int) received_sigterm); - close_listen_socks(); - unlink(options.pid_file); - exit(255); - } - if (key_used && key_do_regen) { - generate_ephemeral_server_key(); - key_used = 0; - key_do_regen = 0; - } - if (ret < 0) - continue; - - for (i = 0; i < options.max_startups; i++) - if (startup_pipes[i] != -1 && - FD_ISSET(startup_pipes[i], fdset)) { - /* - * the read end of the pipe is ready - * if the child has closed the pipe - * after successful authentication - * or if the child has died - */ - close(startup_pipes[i]); - startup_pipes[i] = -1; - startups--; - } - for (i = 0; i < num_listen_socks; i++) { - if (!FD_ISSET(listen_socks[i], fdset)) - continue; - fromlen = sizeof(from); - newsock = accept(listen_socks[i], - (struct sockaddr *)&from, &fromlen); - if (newsock < 0) { - if (errno != EINTR && errno != EWOULDBLOCK) - error("accept: %.100s", strerror(errno)); - continue; - } - if (unset_nonblock(newsock) == -1) { - close(newsock); - continue; - } - if (drop_connection(startups) == 1) { - debug("drop connection #%d", startups); - close(newsock); - continue; - } - if (pipe(startup_p) == -1) { - close(newsock); - continue; - } - - if (rexec_flag && socketpair(AF_UNIX, - SOCK_STREAM, 0, config_s) == -1) { - error("reexec socketpair: %s", - strerror(errno)); - close(newsock); - close(startup_p[0]); - close(startup_p[1]); - continue; - } - - for (j = 0; j < options.max_startups; j++) - if (startup_pipes[j] == -1) { - startup_pipes[j] = startup_p[0]; - if (maxfd < startup_p[0]) - maxfd = startup_p[0]; - startups++; - break; - } - - /* - * Got connection. Fork a child to handle it, unless - * we are in debugging mode. - */ - if (debug_flag) { - /* - * In debugging mode. Close the listening - * socket, and start processing the - * connection without forking. - */ - debug("Server will not fork when running in debugging mode."); - close_listen_socks(); - sock_in = newsock; - sock_out = newsock; - close(startup_p[0]); - close(startup_p[1]); - startup_pipe = -1; - pid = getpid(); - if (rexec_flag) { - send_rexec_state(config_s[0], - &cfg); - close(config_s[0]); - } - break; - } else { - /* - * Normal production daemon. Fork, and have - * the child process the connection. The - * parent continues listening. - */ - if ((pid = fork()) == 0) { - /* - * Child. Close the listening and - * max_startup sockets. Start using - * the accepted socket. Reinitialize - * logging (since our pid has changed). - * We break out of the loop to handle - * the connection. - */ - startup_pipe = startup_p[1]; - close_startup_pipes(); - close_listen_socks(); - sock_in = newsock; - sock_out = newsock; - log_init(__progname, - options.log_level, - options.log_facility, - log_stderr); - if (rexec_flag) - close(config_s[0]); - break; - } - } - - /* Parent. Stay in the loop. */ - if (pid < 0) - error("fork: %.100s", strerror(errno)); - else - debug("Forked child %ld.", (long)pid); - - close(startup_p[1]); - - if (rexec_flag) { - send_rexec_state(config_s[0], &cfg); - close(config_s[0]); - close(config_s[1]); - } - - /* - * Mark that the key has been used (it - * was "given" to the child). - */ - if ((options.protocol & SSH_PROTO_1) && - key_used == 0) { - /* Schedule server key regeneration alarm. */ - signal(SIGALRM, key_regeneration_alarm); - alarm(options.key_regeneration_time); - key_used = 1; - } - - arc4random_stir(); - close(newsock); - } - /* child process check (or debug mode) */ - if (num_listen_socks < 0) - break; - } + /* Accept a connection and return in a forked child */ + server_accept_loop(&sock_in, &sock_out, + &newsock, config_s); } /* This is the child processing a new connection. */ -- 2.45.2