import openssh-4.6p1-gsskex-20070312.patch

1 files changed, 449 insertions, 365 deletions

diff --git a/sshd.c b/sshd.c
index 1eac32797..bfbaa52ca 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: sshd.c,v 1.349 2007/02/21 11:00:05 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -42,7 +43,33 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.318 2005/12/24 02:27:41 djm Exp $");
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#ifdef HAVE_SYS_STAT_H
+# include <sys/stat.h>
+#endif
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+#include "openbsd-compat/sys-tree.h"
+#include <sys/wait.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <netdb.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <grp.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 #include <openssl/dh.h>
 #include <openssl/bn.h>
@@ -53,28 +80,28 @@ RCSID("$OpenBSD: sshd.c,v 1.318 2005/12/24 02:27:41 djm Exp $");
 #include <prot.h>
 #endif
 
+#include "xmalloc.h"
 #include "ssh.h"
 #include "ssh1.h"
 #include "ssh2.h"
-#include "xmalloc.h"
 #include "rsa.h"
 #include "sshpty.h"
 #include "packet.h"
 #include "log.h"
+#include "buffer.h"
 #include "servconf.h"
 #include "uidswap.h"
 #include "compat.h"
-#include "buffer.h"
-#include "bufaux.h"
 #include "cipher.h"
-#include "kex.h"
 #include "key.h"
+#include "kex.h"
 #include "dh.h"
 #include "myproposal.h"
 #include "authfile.h"
 #include "pathnames.h"
 #include "atomicio.h"
 #include "canohost.h"
+#include "hostfile.h"
 #include "auth.h"
 #include "misc.h"
 #include "msg.h"
@@ -83,8 +110,12 @@ RCSID("$OpenBSD: sshd.c,v 1.318 2005/12/24 02:27:41 djm Exp $");
 #include "session.h"
 #include "monitor_mm.h"
 #include "monitor.h"
+#ifdef GSSAPI
+#include "ssh-gss.h"
+#endif
 #include "monitor_wrap.h"
 #include "monitor_fdpass.h"
+#include "version.h"
 
 #ifdef USE_SECURITY_SESSION_API
 #include <Security/AuthSession.h>
@@ -205,15 +236,21 @@ int *startup_pipes = NULL;
 int startup_pipe;               /* in child */
 
 /* variables used for privilege separation */
-int use_privsep;
+int use_privsep = -1;
 struct monitor *pmonitor = NULL;
 
 /* global authentication context */
 Authctxt *the_authctxt = NULL;
 
+/* sshd_config buffer */
+Buffer cfg;
+
 /* message to be displayed after login */
 Buffer loginmsg;
 
+/* Unprivileged user */
+struct passwd *privsep_pw = NULL;
+
 /* Prototypes for various functions defined later in this file. */
 void destroy_sensitive_data(void);
 void demote_sensitive_data(void);
@@ -250,6 +287,8 @@ close_startup_pipes(void)
  * the effect is to reread the configuration file (and to regenerate
  * the server key).
  */
+
+/*ARGSUSED*/
 static void
 sighup_handler(int sig)
 {
@@ -270,6 +309,7 @@ sighup_restart(void)
         logit("Received SIGHUP; restarting.");
         close_listen_socks();
         close_startup_pipes();
+        alarm(0);  /* alarm timer persists across exec */
         execv(saved_argv[0], saved_argv);
         logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
             strerror(errno));
@@ -279,6 +319,7 @@ sighup_restart(void)
 /*
  * Generic signal handler for terminating signals in the master daemon.
  */
+/*ARGSUSED*/
 static void
 sigterm_handler(int sig)
 {
@@ -289,6 +330,7 @@ sigterm_handler(int sig)
  * SIGCHLD handler.  This is called whenever a child dies.  This will then
  * reap any zombies left by exited children.
  */
+/*ARGSUSED*/
 static void
 main_sigchld_handler(int sig)
 {
@@ -307,16 +349,15 @@ main_sigchld_handler(int sig)
 /*
  * Signal handler for the alarm after the login grace period has expired.
  */
+/*ARGSUSED*/
 static void
 grace_alarm_handler(int sig)
 {
-        /* XXX no idea how fix this signal handler */
-
         if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
                 kill(pmonitor->m_pid, SIGALRM);
 
         /* Log error and exit. */
-        fatal("Timeout before authentication for %s", get_remote_ipaddr());
+        sigdie("Timeout before authentication for %s", get_remote_ipaddr());
 }
 
 /*
@@ -349,6 +390,7 @@ generate_ephemeral_server_key(void)
         arc4random_stir();
 }
 
+/*ARGSUSED*/
 static void
 key_regeneration_alarm(int sig)
 {
@@ -545,7 +587,6 @@ privsep_preauth_child(void)
 {
         u_int32_t rnd[256];
         gid_t gidset[1];
-        struct passwd *pw;
         int i;
 
         /* Enable challenge-response authentication for privilege separation */
@@ -558,12 +599,6 @@ privsep_preauth_child(void)
         /* Demote the private keys to public keys. */
         demote_sensitive_data();
 
-        if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
-                fatal("Privilege separation user %s does not exist",
-                    SSH_PRIVSEP_USER);
-        memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
-        endpwent();
-
         /* Change our root directory */
         if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
                 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
@@ -572,16 +607,16 @@ privsep_preauth_child(void)
                 fatal("chdir(\"/\"): %s", strerror(errno));
 
         /* Drop our privileges */
-        debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
-            (u_int)pw->pw_gid);
+        debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
+            (u_int)privsep_pw->pw_gid);
 #if 0
         /* XXX not ready, too heavy after chroot */
-        do_setusercontext(pw);
+        do_setusercontext(privsep_pw);
 #else
-        gidset[0] = pw->pw_gid;
+        gidset[0] = privsep_pw->pw_gid;
         if (setgroups(1, gidset) < 0)
                 fatal("setgroups: %.100s", strerror(errno));
-        permanently_set_uid(pw);
+        permanently_set_uid(privsep_pw);
 #endif
 }
 
@@ -870,6 +905,325 @@ 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.
+                         */
+                        platform_pre_fork();
+                        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.
+                                 */
+                                platform_post_fork_child();
+                                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. */
+                        platform_post_fork_parent(pid);
+                        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.
  */
@@ -878,25 +1232,14 @@ main(int ac, char **av)
 {
         extern char *optarg;
         extern int optind;
-        int opt, j, i, fdsetsz, 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;
-        Buffer cfg;
 
 #ifdef HAVE_SECUREWARE
         (void)set_auth_parameters(ac, av);
@@ -907,7 +1250,7 @@ main(int ac, char **av)
         /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
         saved_argc = ac;
         rexec_argc = ac;
-        saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1));
+        saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
         for (i = 0; i < ac; i++)
                 saved_argv[i] = xstrdup(av[i]);
         saved_argv[i] = NULL;
@@ -969,7 +1312,8 @@ main(int ac, char **av)
                         options.log_level = SYSLOG_LEVEL_QUIET;
                         break;
                 case 'b':
-                        options.server_key_bits = atoi(optarg);
+                        options.server_key_bits = (int)strtonum(optarg, 256,
+                            32768, NULL);
                         break;
                 case 'p':
                         options.ports_from_cmdline = 1;
@@ -1006,7 +1350,7 @@ main(int ac, char **av)
                         test_flag = 1;
                         break;
                 case 'u':
-                        utmp_len = atoi(optarg);
+                        utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
                         if (utmp_len > MAXHOSTNAMELEN) {
                                 fprintf(stderr, "Invalid utmp length.\n");
                                 exit(1);
@@ -1015,7 +1359,7 @@ main(int ac, char **av)
                 case 'o':
                         line = xstrdup(optarg);
                         if (process_server_config_line(&options, line,
-                            "command-line", 0) != 0)
+                            "command-line", 0, NULL, NULL, NULL, NULL) != 0)
                                 exit(1);
                         xfree(line);
                         break;
@@ -1073,11 +1417,8 @@ main(int ac, char **av)
         else
                 load_server_config(config_file_name, &cfg);
 
-        parse_server_config(&options,
-            rexeced_flag ? "rexec" : config_file_name, &cfg);
-
-        if (!rexec_flag)
-                buffer_free(&cfg);
+        parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
+            &cfg, NULL, NULL, NULL);
 
         seed_rng();
 
@@ -1095,8 +1436,21 @@ main(int ac, char **av)
 
         debug("sshd version %.100s", SSH_RELEASE);
 
+        /* Store privilege separation user for later use if required. */
+        if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
+                if (use_privsep || options.kerberos_authentication)
+                        fatal("Privilege separation user %s does not exist",
+                            SSH_PRIVSEP_USER);
+        } else {
+                memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
+                privsep_pw = pwcopy(privsep_pw);
+                xfree(privsep_pw->pw_passwd);
+                privsep_pw->pw_passwd = xstrdup("*");
+        }
+        endpwent();
+
         /* load private host keys */
-        sensitive_data.host_keys = xmalloc(options.num_host_key_files *
+        sensitive_data.host_keys = xcalloc(options.num_host_key_files,
             sizeof(Key *));
         for (i = 0; i < options.num_host_key_files; i++)
                 sensitive_data.host_keys[i] = NULL;
@@ -1165,12 +1519,8 @@ main(int ac, char **av)
         }
 
         if (use_privsep) {
-                struct passwd *pw;
                 struct stat st;
 
-                if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
-                        fatal("Privilege separation user %s does not exist",
-                            SSH_PRIVSEP_USER);
                 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
                     (S_ISDIR(st.st_mode) == 0))
                         fatal("Missing privilege separation directory: %s",
@@ -1202,7 +1552,7 @@ main(int ac, char **av)
                 debug("setgroups() failed: %.200s", strerror(errno));
 
         if (rexec_flag) {
-                rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2));
+                rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
                 for (i = 0; i < rexec_argc; i++) {
                         debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
                         rexec_argv[i] = saved_argv[i];
@@ -1250,121 +1600,31 @@ 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. */
-                        logit("Server listening on %s port %s.", ntop, strport);
-                        if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
-                                fatal("listen: %.100s", strerror(errno));
-
-                }
-                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));
@@ -1374,194 +1634,9 @@ 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 = xmalloc(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);
-                        fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
-                        fdset = (fd_set *)xmalloc(fdsetsz);
-                        memset(fdset, 0, fdsetsz);
-
-                        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 the new socket (the child is now taking care of it). */
-                                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. */
@@ -1656,7 +1731,13 @@ main(int ac, char **av)
          * We use get_canonical_hostname with usedns = 0 instead of
          * get_remote_ipaddr here so IP options will be checked.
          */
-        remote_ip = get_canonical_hostname(0);
+        (void) get_canonical_hostname(0);
+        /*
+         * The rest of the code depends on the fact that
+         * get_remote_ipaddr() caches the remote ip, even if
+         * the socket goes away.
+         */
+        remote_ip = get_remote_ipaddr();
 
 #ifdef SSH_AUDIT_EVENTS
         audit_connection_from(remote_ip, remote_port);
@@ -1752,8 +1833,7 @@ main(int ac, char **av)
         packet_set_nonblocking();
 
         /* allocate authentication context */
-        authctxt = xmalloc(sizeof(*authctxt));
-        memset(authctxt, 0, sizeof(*authctxt));
+        authctxt = xcalloc(1, sizeof(*authctxt));
 
         authctxt->loginmsg = &loginmsg;
 
@@ -1792,6 +1872,7 @@ main(int ac, char **av)
          */
         alarm(0);
         signal(SIGALRM, SIG_DFL);
+        authctxt->authenticated = 1;
         if (startup_pipe != -1) {
                 close(startup_pipe);
                 startup_pipe = -1;
@@ -1844,11 +1925,14 @@ ssh1_session_key(BIGNUM *session_key_int)
 {
         int rsafail = 0;
 
-        if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
+        if (BN_cmp(sensitive_data.server_key->rsa->n,
+            sensitive_data.ssh1_host_key->rsa->n) > 0) {
                 /* Server key has bigger modulus. */
                 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
-                    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
-                        fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
+                    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
+                    SSH_KEY_BITS_RESERVED) {
+                        fatal("do_connection: %s: "
+                            "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
                             get_remote_ipaddr(),
                             BN_num_bits(sensitive_data.server_key->rsa->n),
                             BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
@@ -1863,8 +1947,10 @@ ssh1_session_key(BIGNUM *session_key_int)
         } else {
                 /* Host key has bigger modulus (or they are equal). */
                 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
-                    BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
-                        fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
+                    BN_num_bits(sensitive_data.server_key->rsa->n) +
+                    SSH_KEY_BITS_RESERVED) {
+                        fatal("do_connection: %s: "
+                            "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
                             get_remote_ipaddr(),
                             BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
                             BN_num_bits(sensitive_data.server_key->rsa->n),
@@ -1989,10 +2075,10 @@ do_ssh1_kex(void)
          * key is in the highest bits.
          */
         if (!rsafail) {
-                BN_mask_bits(session_key_int, sizeof(session_key) * 8);
+                (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
                 len = BN_num_bytes(session_key_int);
                 if (len < 0 || (u_int)len > sizeof(session_key)) {
-                        error("do_connection: bad session key len from %s: "
+                        error("do_ssh1_kex: bad session key len from %s: "
                             "session_key_int %d > sizeof(session_key) %lu",
                             get_remote_ipaddr(), len, (u_long)sizeof(session_key));
                         rsafail++;
@@ -2085,11 +2171,9 @@ do_ssh2_kex(void)
                 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
                 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
         }
-        
+
         myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
 
-        /* start key exchange */
-  
 #ifdef GSSAPI
         {
         char *orig;
@@ -2098,8 +2182,8 @@ do_ssh2_kex(void)
         orig = myproposal[PROPOSAL_KEX_ALGS];
 
         /* 
-         * If we don't have a host key, then there's no point advertising
-         * the other key exchange algorithms
+         * If we don't have a host key, then there's no point advertising
+         * the other key exchange algorithms
          */
 
         if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]) == 0)
@@ -2110,15 +2194,13 @@ do_ssh2_kex(void)
         else
                 gss = NULL;
 
-        if (gss && orig) {
-                int len = strlen(orig) + strlen(gss) + 2;
-                newstr = xmalloc(len);
-                snprintf(newstr, len, "%s,%s", gss, orig);
-        } else if (gss) {
+        if (gss && orig)
+                xasprintf(&newstr, "%s,%s", gss, orig);
+        else if (gss)
                 newstr = gss;
-        } else if (orig) {
+        else if (orig)
                 newstr = orig;
-        }
+
         /* 
          * If we've got GSSAPI mechanisms, then we've got the 'null' host
          * key alg, but we can't tell people about it unless its the only
@@ -2134,18 +2216,20 @@ do_ssh2_kex(void)
         }
 #endif
 
-        /* start key exchange */
-        kex = kex_setup(myproposal);
-        kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
+        /* start key exchange */
+        kex = kex_setup(myproposal);
+        kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
         kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
         kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
+        kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
 #ifdef GSSAPI
         kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server;
+        kex->kex[KEX_GSS_GRP14_SHA1] = kexgss_server;
         kex->kex[KEX_GSS_GEX_SHA1] = kexgss_server;
 #endif
-        kex->server = 1;
-        kex->client_version_string=client_version_string;
-        kex->server_version_string=server_version_string;
+        kex->server = 1;
+        kex->client_version_string=client_version_string;
+        kex->server_version_string=server_version_string;
         kex->load_host_key=&get_hostkey_by_type;
         kex->host_key_index=&get_hostkey_index;