diff options
Diffstat (limited to 'crypto/openssh/sshd.c')
| -rw-r--r-- | crypto/openssh/sshd.c | 2156 |
1 files changed, 0 insertions, 2156 deletions
diff --git a/crypto/openssh/sshd.c b/crypto/openssh/sshd.c deleted file mode 100644 index 4aa1c98..0000000 --- a/crypto/openssh/sshd.c +++ /dev/null @@ -1,2156 +0,0 @@ -/* $OpenBSD: sshd.c,v 1.348 2006/11/06 21:25:28 markus Exp $ */ -/* - * Author: Tatu Ylonen <ylo@cs.hut.fi> - * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland - * All rights reserved - * This program is the ssh daemon. It listens for connections from clients, - * and performs authentication, executes use commands or shell, and forwards - * information to/from the application to the user client over an encrypted - * connection. This can also handle forwarding of X11, TCP/IP, and - * authentication agent connections. - * - * As far as I am concerned, the code I have written for this software - * can be used freely for any purpose. Any derived versions of this - * software must be clearly marked as such, and if the derived work is - * incompatible with the protocol description in the RFC file, it must be - * called by a name other than "ssh" or "Secure Shell". - * - * SSH2 implementation: - * Privilege Separation: - * - * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. - * Copyright (c) 2002 Niels Provos. All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * - * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR - * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES - * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. - * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, - * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT - * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF - * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -#include "includes.h" - -#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> -#include <openssl/md5.h> -#include <openssl/rand.h> -#ifdef HAVE_SECUREWARE -#include <sys/security.h> -#include <prot.h> -#endif - -#include "xmalloc.h" -#include "ssh.h" -#include "ssh1.h" -#include "ssh2.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 "cipher.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" -#include "dispatch.h" -#include "channels.h" -#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 LIBWRAP -#include <tcpd.h> -#include <syslog.h> -int allow_severity = LOG_INFO; -int deny_severity = LOG_WARNING; -#endif /* LIBWRAP */ - -#ifndef O_NOCTTY -#define O_NOCTTY 0 -#endif - -/* Re-exec fds */ -#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) -#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) -#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) -#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) - -extern char *__progname; - -/* Server configuration options. */ -ServerOptions options; - -/* Name of the server configuration file. */ -char *config_file_name = _PATH_SERVER_CONFIG_FILE; - -/* - * Debug mode flag. This can be set on the command line. If debug - * mode is enabled, extra debugging output will be sent to the system - * log, the daemon will not go to background, and will exit after processing - * the first connection. - */ -int debug_flag = 0; - -/* Flag indicating that the daemon should only test the configuration and keys. */ -int test_flag = 0; - -/* Flag indicating that the daemon is being started from inetd. */ -int inetd_flag = 0; - -/* Flag indicating that sshd should not detach and become a daemon. */ -int no_daemon_flag = 0; - -/* debug goes to stderr unless inetd_flag is set */ -int log_stderr = 0; - -/* Saved arguments to main(). */ -char **saved_argv; -int saved_argc; - -/* re-exec */ -int rexeced_flag = 0; -int rexec_flag = 1; -int rexec_argc = 0; -char **rexec_argv; - -/* - * The sockets that the server is listening; this is used in the SIGHUP - * signal handler. - */ -#define MAX_LISTEN_SOCKS 16 -int listen_socks[MAX_LISTEN_SOCKS]; -int num_listen_socks = 0; - -/* - * the client's version string, passed by sshd2 in compat mode. if != NULL, - * sshd will skip the version-number exchange - */ -char *client_version_string = NULL; -char *server_version_string = NULL; - -/* for rekeying XXX fixme */ -Kex *xxx_kex; - -/* - * Any really sensitive data in the application is contained in this - * structure. The idea is that this structure could be locked into memory so - * that the pages do not get written into swap. However, there are some - * problems. The private key contains BIGNUMs, and we do not (in principle) - * have access to the internals of them, and locking just the structure is - * not very useful. Currently, memory locking is not implemented. - */ -struct { - Key *server_key; /* ephemeral server key */ - Key *ssh1_host_key; /* ssh1 host key */ - Key **host_keys; /* all private host keys */ - int have_ssh1_key; - int have_ssh2_key; - u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; -} sensitive_data; - -/* - * Flag indicating whether the RSA server key needs to be regenerated. - * Is set in the SIGALRM handler and cleared when the key is regenerated. - */ -static volatile sig_atomic_t key_do_regen = 0; - -/* This is set to true when a signal is received. */ -static volatile sig_atomic_t received_sighup = 0; -static volatile sig_atomic_t received_sigterm = 0; - -/* session identifier, used by RSA-auth */ -u_char session_id[16]; - -/* same for ssh2 */ -u_char *session_id2 = NULL; -u_int session_id2_len = 0; - -/* record remote hostname or ip */ -u_int utmp_len = MAXHOSTNAMELEN; - -/* options.max_startup sized array of fd ints */ -int *startup_pipes = NULL; -int startup_pipe; /* in child */ - -/* variables used for privilege separation */ -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); - -static void do_ssh1_kex(void); -static void do_ssh2_kex(void); - -/* - * Close all listening sockets - */ -static void -close_listen_socks(void) -{ - int i; - - for (i = 0; i < num_listen_socks; i++) - close(listen_socks[i]); - num_listen_socks = -1; -} - -static void -close_startup_pipes(void) -{ - int i; - - if (startup_pipes) - for (i = 0; i < options.max_startups; i++) - if (startup_pipes[i] != -1) - close(startup_pipes[i]); -} - -/* - * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; - * the effect is to reread the configuration file (and to regenerate - * the server key). - */ - -/*ARGSUSED*/ -static void -sighup_handler(int sig) -{ - int save_errno = errno; - - received_sighup = 1; - signal(SIGHUP, sighup_handler); - errno = save_errno; -} - -/* - * Called from the main program after receiving SIGHUP. - * Restarts the server. - */ -static void -sighup_restart(void) -{ - logit("Received SIGHUP; restarting."); - close_listen_socks(); - close_startup_pipes(); - execv(saved_argv[0], saved_argv); - logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], - strerror(errno)); - exit(1); -} - -/* - * Generic signal handler for terminating signals in the master daemon. - */ -/*ARGSUSED*/ -static void -sigterm_handler(int sig) -{ - received_sigterm = 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) -{ - int save_errno = errno; - pid_t pid; - int status; - - while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || - (pid < 0 && errno == EINTR)) - ; - - signal(SIGCHLD, main_sigchld_handler); - errno = save_errno; -} - -/* - * Signal handler for the alarm after the login grace period has expired. - */ -/*ARGSUSED*/ -static void -grace_alarm_handler(int sig) -{ - if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) - kill(pmonitor->m_pid, SIGALRM); - - /* Log error and exit. */ - sigdie("Timeout before authentication for %s", get_remote_ipaddr()); -} - -/* - * Signal handler for the key regeneration alarm. Note that this - * alarm only occurs in the daemon waiting for connections, and it does not - * do anything with the private key or random state before forking. - * Thus there should be no concurrency control/asynchronous execution - * problems. - */ -static void -generate_ephemeral_server_key(void) -{ - u_int32_t rnd = 0; - int i; - - verbose("Generating %s%d bit RSA key.", - sensitive_data.server_key ? "new " : "", options.server_key_bits); - if (sensitive_data.server_key != NULL) - key_free(sensitive_data.server_key); - sensitive_data.server_key = key_generate(KEY_RSA1, - options.server_key_bits); - verbose("RSA key generation complete."); - - for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { - if (i % 4 == 0) - rnd = arc4random(); - sensitive_data.ssh1_cookie[i] = rnd & 0xff; - rnd >>= 8; - } - arc4random_stir(); -} - -/*ARGSUSED*/ -static void -key_regeneration_alarm(int sig) -{ - int save_errno = errno; - - signal(SIGALRM, SIG_DFL); - errno = save_errno; - key_do_regen = 1; -} - -static void -sshd_exchange_identification(int sock_in, int sock_out) -{ - u_int i; - int mismatch; - int remote_major, remote_minor; - int major, minor; - char *s; - char buf[256]; /* Must not be larger than remote_version. */ - char remote_version[256]; /* Must be at least as big as buf. */ - - if ((options.protocol & SSH_PROTO_1) && - (options.protocol & SSH_PROTO_2)) { - major = PROTOCOL_MAJOR_1; - minor = 99; - } else if (options.protocol & SSH_PROTO_2) { - major = PROTOCOL_MAJOR_2; - minor = PROTOCOL_MINOR_2; - } else { - major = PROTOCOL_MAJOR_1; - minor = PROTOCOL_MINOR_1; - } - snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); - server_version_string = xstrdup(buf); - - /* Send our protocol version identification. */ - if (atomicio(vwrite, sock_out, server_version_string, - strlen(server_version_string)) - != strlen(server_version_string)) { - logit("Could not write ident string to %s", get_remote_ipaddr()); - cleanup_exit(255); - } - - /* Read other sides version identification. */ - memset(buf, 0, sizeof(buf)); - for (i = 0; i < sizeof(buf) - 1; i++) { - if (atomicio(read, sock_in, &buf[i], 1) != 1) { - logit("Did not receive identification string from %s", - get_remote_ipaddr()); - cleanup_exit(255); - } - if (buf[i] == '\r') { - buf[i] = 0; - /* Kludge for F-Secure Macintosh < 1.0.2 */ - if (i == 12 && - strncmp(buf, "SSH-1.5-W1.0", 12) == 0) - break; - continue; - } - if (buf[i] == '\n') { - buf[i] = 0; - break; - } - } - buf[sizeof(buf) - 1] = 0; - client_version_string = xstrdup(buf); - - /* - * Check that the versions match. In future this might accept - * several versions and set appropriate flags to handle them. - */ - if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", - &remote_major, &remote_minor, remote_version) != 3) { - s = "Protocol mismatch.\n"; - (void) atomicio(vwrite, sock_out, s, strlen(s)); - close(sock_in); - close(sock_out); - logit("Bad protocol version identification '%.100s' from %s", - client_version_string, get_remote_ipaddr()); - cleanup_exit(255); - } - debug("Client protocol version %d.%d; client software version %.100s", - remote_major, remote_minor, remote_version); - - compat_datafellows(remote_version); - - if (datafellows & SSH_BUG_PROBE) { - logit("probed from %s with %s. Don't panic.", - get_remote_ipaddr(), client_version_string); - cleanup_exit(255); - } - - if (datafellows & SSH_BUG_SCANNER) { - logit("scanned from %s with %s. Don't panic.", - get_remote_ipaddr(), client_version_string); - cleanup_exit(255); - } - - mismatch = 0; - switch (remote_major) { - case 1: - if (remote_minor == 99) { - if (options.protocol & SSH_PROTO_2) - enable_compat20(); - else - mismatch = 1; - break; - } - if (!(options.protocol & SSH_PROTO_1)) { - mismatch = 1; - break; - } - if (remote_minor < 3) { - packet_disconnect("Your ssh version is too old and " - "is no longer supported. Please install a newer version."); - } else if (remote_minor == 3) { - /* note that this disables agent-forwarding */ - enable_compat13(); - } - break; - case 2: - if (options.protocol & SSH_PROTO_2) { - enable_compat20(); - break; - } - /* FALLTHROUGH */ - default: - mismatch = 1; - break; - } - chop(server_version_string); - debug("Local version string %.200s", server_version_string); - - if (mismatch) { - s = "Protocol major versions differ.\n"; - (void) atomicio(vwrite, sock_out, s, strlen(s)); - close(sock_in); - close(sock_out); - logit("Protocol major versions differ for %s: %.200s vs. %.200s", - get_remote_ipaddr(), - server_version_string, client_version_string); - cleanup_exit(255); - } -} - -/* Destroy the host and server keys. They will no longer be needed. */ -void -destroy_sensitive_data(void) -{ - int i; - - if (sensitive_data.server_key) { - key_free(sensitive_data.server_key); - sensitive_data.server_key = NULL; - } - for (i = 0; i < options.num_host_key_files; i++) { - if (sensitive_data.host_keys[i]) { - key_free(sensitive_data.host_keys[i]); - sensitive_data.host_keys[i] = NULL; - } - } - sensitive_data.ssh1_host_key = NULL; - memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); -} - -/* Demote private to public keys for network child */ -void -demote_sensitive_data(void) -{ - Key *tmp; - int i; - - if (sensitive_data.server_key) { - tmp = key_demote(sensitive_data.server_key); - key_free(sensitive_data.server_key); - sensitive_data.server_key = tmp; - } - - for (i = 0; i < options.num_host_key_files; i++) { - if (sensitive_data.host_keys[i]) { - tmp = key_demote(sensitive_data.host_keys[i]); - key_free(sensitive_data.host_keys[i]); - sensitive_data.host_keys[i] = tmp; - if (tmp->type == KEY_RSA1) - sensitive_data.ssh1_host_key = tmp; - } - } - - /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ -} - -static void -privsep_preauth_child(void) -{ - u_int32_t rnd[256]; - gid_t gidset[1]; - int i; - - /* Enable challenge-response authentication for privilege separation */ - privsep_challenge_enable(); - - for (i = 0; i < 256; i++) - rnd[i] = arc4random(); - RAND_seed(rnd, sizeof(rnd)); - - /* Demote the private keys to public keys. */ - demote_sensitive_data(); - - /* Change our root directory */ - if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) - fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, - strerror(errno)); - if (chdir("/") == -1) - fatal("chdir(\"/\"): %s", strerror(errno)); - - /* Drop our privileges */ - 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(privsep_pw); -#else - gidset[0] = privsep_pw->pw_gid; - if (setgroups(1, gidset) < 0) - fatal("setgroups: %.100s", strerror(errno)); - permanently_set_uid(privsep_pw); -#endif -} - -static int -privsep_preauth(Authctxt *authctxt) -{ - int status; - pid_t pid; - - /* Set up unprivileged child process to deal with network data */ - pmonitor = monitor_init(); - /* Store a pointer to the kex for later rekeying */ - pmonitor->m_pkex = &xxx_kex; - - pid = fork(); - if (pid == -1) { - fatal("fork of unprivileged child failed"); - } else if (pid != 0) { - debug2("Network child is on pid %ld", (long)pid); - - close(pmonitor->m_recvfd); - pmonitor->m_pid = pid; - monitor_child_preauth(authctxt, pmonitor); - close(pmonitor->m_sendfd); - - /* Sync memory */ - monitor_sync(pmonitor); - - /* Wait for the child's exit status */ - while (waitpid(pid, &status, 0) < 0) - if (errno != EINTR) - break; - return (1); - } else { - /* child */ - - close(pmonitor->m_sendfd); - - /* Demote the child */ - if (getuid() == 0 || geteuid() == 0) - privsep_preauth_child(); - setproctitle("%s", "[net]"); - } - return (0); -} - -static void -privsep_postauth(Authctxt *authctxt) -{ -#ifdef DISABLE_FD_PASSING - if (1) { -#else - if (authctxt->pw->pw_uid == 0 || options.use_login) { -#endif - /* File descriptor passing is broken or root login */ - use_privsep = 0; - goto skip; - } - - /* New socket pair */ - monitor_reinit(pmonitor); - - pmonitor->m_pid = fork(); - if (pmonitor->m_pid == -1) - fatal("fork of unprivileged child failed"); - else if (pmonitor->m_pid != 0) { - debug2("User child is on pid %ld", (long)pmonitor->m_pid); - close(pmonitor->m_recvfd); - buffer_clear(&loginmsg); - monitor_child_postauth(pmonitor); - - /* NEVERREACHED */ - exit(0); - } - - close(pmonitor->m_sendfd); - - /* Demote the private keys to public keys. */ - demote_sensitive_data(); - - /* Drop privileges */ - do_setusercontext(authctxt->pw); - - skip: - /* It is safe now to apply the key state */ - monitor_apply_keystate(pmonitor); - - /* - * Tell the packet layer that authentication was successful, since - * this information is not part of the key state. - */ - packet_set_authenticated(); -} - -static char * -list_hostkey_types(void) -{ - Buffer b; - const char *p; - char *ret; - int i; - - buffer_init(&b); - for (i = 0; i < options.num_host_key_files; i++) { - Key *key = sensitive_data.host_keys[i]; - if (key == NULL) - continue; - switch (key->type) { - case KEY_RSA: - case KEY_DSA: - if (buffer_len(&b) > 0) - buffer_append(&b, ",", 1); - p = key_ssh_name(key); - buffer_append(&b, p, strlen(p)); - break; - } - } - buffer_append(&b, "\0", 1); - ret = xstrdup(buffer_ptr(&b)); - buffer_free(&b); - debug("list_hostkey_types: %s", ret); - return ret; -} - -Key * -get_hostkey_by_type(int type) -{ - int i; - - for (i = 0; i < options.num_host_key_files; i++) { - Key *key = sensitive_data.host_keys[i]; - if (key != NULL && key->type == type) - return key; - } - return NULL; -} - -Key * -get_hostkey_by_index(int ind) -{ - if (ind < 0 || ind >= options.num_host_key_files) - return (NULL); - return (sensitive_data.host_keys[ind]); -} - -int -get_hostkey_index(Key *key) -{ - int i; - - for (i = 0; i < options.num_host_key_files; i++) { - if (key == sensitive_data.host_keys[i]) - return (i); - } - return (-1); -} - -/* - * returns 1 if connection should be dropped, 0 otherwise. - * dropping starts at connection #max_startups_begin with a probability - * of (max_startups_rate/100). the probability increases linearly until - * all connections are dropped for startups > max_startups - */ -static int -drop_connection(int startups) -{ - int p, r; - - if (startups < options.max_startups_begin) - return 0; - if (startups >= options.max_startups) - return 1; - if (options.max_startups_rate == 100) - return 1; - - p = 100 - options.max_startups_rate; - p *= startups - options.max_startups_begin; - p /= options.max_startups - options.max_startups_begin; - p += options.max_startups_rate; - r = arc4random() % 100; - - debug("drop_connection: p %d, r %d", p, r); - return (r < p) ? 1 : 0; -} - -static void -usage(void) -{ - fprintf(stderr, "%s, %s\n", - SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); - fprintf(stderr, -"usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n" -" [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n" - ); - exit(1); -} - -static void -send_rexec_state(int fd, Buffer *conf) -{ - Buffer m; - - debug3("%s: entering fd = %d config len %d", __func__, fd, - buffer_len(conf)); - - /* - * Protocol from reexec master to child: - * string configuration - * u_int ephemeral_key_follows - * bignum e (only if ephemeral_key_follows == 1) - * bignum n " - * bignum d " - * bignum iqmp " - * bignum p " - * bignum q " - * string rngseed (only if OpenSSL is not self-seeded) - */ - buffer_init(&m); - buffer_put_cstring(&m, buffer_ptr(conf)); - - if (sensitive_data.server_key != NULL && - sensitive_data.server_key->type == KEY_RSA1) { - buffer_put_int(&m, 1); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); - buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); - } else - buffer_put_int(&m, 0); - -#ifndef OPENSSL_PRNG_ONLY - rexec_send_rng_seed(&m); -#endif - - if (ssh_msg_send(fd, 0, &m) == -1) - fatal("%s: ssh_msg_send failed", __func__); - - buffer_free(&m); - - debug3("%s: done", __func__); -} - -static void -recv_rexec_state(int fd, Buffer *conf) -{ - Buffer m; - char *cp; - u_int len; - - debug3("%s: entering fd = %d", __func__, fd); - - buffer_init(&m); - - if (ssh_msg_recv(fd, &m) == -1) - fatal("%s: ssh_msg_recv failed", __func__); - if (buffer_get_char(&m) != 0) - fatal("%s: rexec version mismatch", __func__); - - cp = buffer_get_string(&m, &len); - if (conf != NULL) - buffer_append(conf, cp, len + 1); - xfree(cp); - - if (buffer_get_int(&m)) { - if (sensitive_data.server_key != NULL) - key_free(sensitive_data.server_key); - sensitive_data.server_key = key_new_private(KEY_RSA1); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); - buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); - rsa_generate_additional_parameters( - sensitive_data.server_key->rsa); - } - -#ifndef OPENSSL_PRNG_ONLY - rexec_recv_rng_seed(&m); -#endif - - buffer_free(&m); - - 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. - */ -int -main(int ac, char **av) -{ - extern char *optarg; - extern int optind; - int opt, i, on = 1; - int sock_in = -1, sock_out = -1, newsock = -1; - const char *remote_ip; - int remote_port; - char *line; - int config_s[2] = { -1 , -1 }; - Key *key; - Authctxt *authctxt; - -#ifdef HAVE_SECUREWARE - (void)set_auth_parameters(ac, av); -#endif - __progname = ssh_get_progname(av[0]); - init_rng(); - - /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ - saved_argc = ac; - rexec_argc = ac; - saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); - for (i = 0; i < ac; i++) - saved_argv[i] = xstrdup(av[i]); - saved_argv[i] = NULL; - -#ifndef HAVE_SETPROCTITLE - /* Prepare for later setproctitle emulation */ - compat_init_setproctitle(ac, av); - av = saved_argv; -#endif - - if (geteuid() == 0 && setgroups(0, NULL) == -1) - debug("setgroups(): %.200s", strerror(errno)); - - /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ - sanitise_stdfd(); - - /* Initialize configuration options to their default values. */ - initialize_server_options(&options); - - /* Parse command-line arguments. */ - while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) { - switch (opt) { - case '4': - options.address_family = AF_INET; - break; - case '6': - options.address_family = AF_INET6; - break; - case 'f': - config_file_name = optarg; - break; - case 'd': - if (debug_flag == 0) { - debug_flag = 1; - options.log_level = SYSLOG_LEVEL_DEBUG1; - } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) - options.log_level++; - break; - case 'D': - no_daemon_flag = 1; - break; - case 'e': - log_stderr = 1; - break; - case 'i': - inetd_flag = 1; - break; - case 'r': - rexec_flag = 0; - break; - case 'R': - rexeced_flag = 1; - inetd_flag = 1; - break; - case 'Q': - /* ignored */ - break; - case 'q': - options.log_level = SYSLOG_LEVEL_QUIET; - break; - case 'b': - options.server_key_bits = (int)strtonum(optarg, 256, - 32768, NULL); - break; - case 'p': - options.ports_from_cmdline = 1; - if (options.num_ports >= MAX_PORTS) { - fprintf(stderr, "too many ports.\n"); - exit(1); - } - options.ports[options.num_ports++] = a2port(optarg); - if (options.ports[options.num_ports-1] == 0) { - fprintf(stderr, "Bad port number.\n"); - exit(1); - } - break; - case 'g': - if ((options.login_grace_time = convtime(optarg)) == -1) { - fprintf(stderr, "Invalid login grace time.\n"); - exit(1); - } - break; - case 'k': - if ((options.key_regeneration_time = convtime(optarg)) == -1) { - fprintf(stderr, "Invalid key regeneration interval.\n"); - exit(1); - } - break; - case 'h': - if (options.num_host_key_files >= MAX_HOSTKEYS) { - fprintf(stderr, "too many host keys.\n"); - exit(1); - } - options.host_key_files[options.num_host_key_files++] = optarg; - break; - case 't': - test_flag = 1; - break; - case 'u': - utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); - if (utmp_len > MAXHOSTNAMELEN) { - fprintf(stderr, "Invalid utmp length.\n"); - exit(1); - } - break; - case 'o': - line = xstrdup(optarg); - if (process_server_config_line(&options, line, - "command-line", 0, NULL, NULL, NULL, NULL) != 0) - exit(1); - xfree(line); - break; - case '?': - default: - usage(); - break; - } - } - if (rexeced_flag || inetd_flag) - rexec_flag = 0; - if (rexec_flag && (av[0] == NULL || *av[0] != '/')) - fatal("sshd re-exec requires execution with an absolute path"); - if (rexeced_flag) - closefrom(REEXEC_MIN_FREE_FD); - else - closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); - - SSLeay_add_all_algorithms(); - - /* - * Force logging to stderr until we have loaded the private host - * key (unless started from inetd) - */ - log_init(__progname, - options.log_level == SYSLOG_LEVEL_NOT_SET ? - SYSLOG_LEVEL_INFO : options.log_level, - options.log_facility == SYSLOG_FACILITY_NOT_SET ? - SYSLOG_FACILITY_AUTH : options.log_facility, - log_stderr || !inetd_flag); - - /* - * Unset KRB5CCNAME, otherwise the user's session may inherit it from - * root's environment - */ - if (getenv("KRB5CCNAME") != NULL) - unsetenv("KRB5CCNAME"); - -#ifdef _UNICOS - /* Cray can define user privs drop all privs now! - * Not needed on PRIV_SU systems! - */ - drop_cray_privs(); -#endif - - sensitive_data.server_key = NULL; - sensitive_data.ssh1_host_key = NULL; - sensitive_data.have_ssh1_key = 0; - sensitive_data.have_ssh2_key = 0; - - /* Fetch our configuration */ - buffer_init(&cfg); - if (rexeced_flag) - recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); - else - load_server_config(config_file_name, &cfg); - - parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, - &cfg, NULL, NULL, NULL); - - seed_rng(); - - /* Fill in default values for those options not explicitly set. */ - fill_default_server_options(&options); - - /* set default channel AF */ - channel_set_af(options.address_family); - - /* Check that there are no remaining arguments. */ - if (optind < ac) { - fprintf(stderr, "Extra argument %s.\n", av[optind]); - exit(1); - } - - 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 = xcalloc(options.num_host_key_files, - sizeof(Key *)); - for (i = 0; i < options.num_host_key_files; i++) - sensitive_data.host_keys[i] = NULL; - - for (i = 0; i < options.num_host_key_files; i++) { - key = key_load_private(options.host_key_files[i], "", NULL); - sensitive_data.host_keys[i] = key; - if (key == NULL) { - error("Could not load host key: %s", - options.host_key_files[i]); - sensitive_data.host_keys[i] = NULL; - continue; - } - switch (key->type) { - case KEY_RSA1: - sensitive_data.ssh1_host_key = key; - sensitive_data.have_ssh1_key = 1; - break; - case KEY_RSA: - case KEY_DSA: - sensitive_data.have_ssh2_key = 1; - break; - } - debug("private host key: #%d type %d %s", i, key->type, - key_type(key)); - } - if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { - logit("Disabling protocol version 1. Could not load host key"); - options.protocol &= ~SSH_PROTO_1; - } - if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { - logit("Disabling protocol version 2. Could not load host key"); - options.protocol &= ~SSH_PROTO_2; - } - if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { - logit("sshd: no hostkeys available -- exiting."); - exit(1); - } - - /* Check certain values for sanity. */ - if (options.protocol & SSH_PROTO_1) { - if (options.server_key_bits < 512 || - options.server_key_bits > 32768) { - fprintf(stderr, "Bad server key size.\n"); - exit(1); - } - /* - * Check that server and host key lengths differ sufficiently. This - * is necessary to make double encryption work with rsaref. Oh, I - * hate software patents. I dont know if this can go? Niels - */ - if (options.server_key_bits > - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - - SSH_KEY_BITS_RESERVED && options.server_key_bits < - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + - SSH_KEY_BITS_RESERVED) { - options.server_key_bits = - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + - SSH_KEY_BITS_RESERVED; - debug("Forcing server key to %d bits to make it differ from host key.", - options.server_key_bits); - } - } - - if (use_privsep) { - struct stat st; - - if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || - (S_ISDIR(st.st_mode) == 0)) - fatal("Missing privilege separation directory: %s", - _PATH_PRIVSEP_CHROOT_DIR); - -#ifdef HAVE_CYGWIN - if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && - (st.st_uid != getuid () || - (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) -#else - if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) -#endif - fatal("%s must be owned by root and not group or " - "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); - } - - /* Configuration looks good, so exit if in test mode. */ - if (test_flag) - exit(0); - - /* - * Clear out any supplemental groups we may have inherited. This - * prevents inadvertent creation of files with bad modes (in the - * portable version at least, it's certainly possible for PAM - * to create a file, and we can't control the code in every - * module which might be used). - */ - if (setgroups(0, NULL) < 0) - debug("setgroups() failed: %.200s", strerror(errno)); - - if (rexec_flag) { - 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]; - } - rexec_argv[rexec_argc] = "-R"; - rexec_argv[rexec_argc + 1] = NULL; - } - - /* Initialize the log (it is reinitialized below in case we forked). */ - if (debug_flag && (!inetd_flag || rexeced_flag)) - log_stderr = 1; - log_init(__progname, options.log_level, options.log_facility, log_stderr); - - /* - * If not in debugging mode, and not started from inetd, disconnect - * from the controlling terminal, and fork. The original process - * exits. - */ - if (!(debug_flag || inetd_flag || no_daemon_flag)) { -#ifdef TIOCNOTTY - int fd; -#endif /* TIOCNOTTY */ - if (daemon(0, 0) < 0) - fatal("daemon() failed: %.200s", strerror(errno)); - - /* Disconnect from the controlling tty. */ -#ifdef TIOCNOTTY - fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); - if (fd >= 0) { - (void) ioctl(fd, TIOCNOTTY, NULL); - close(fd); - } -#endif /* TIOCNOTTY */ - } - /* Reinitialize the log (because of the fork above). */ - log_init(__progname, options.log_level, options.log_facility, log_stderr); - - /* Initialize the random number generator. */ - arc4random_stir(); - - /* Chdir to the root directory so that the current disk can be - unmounted if desired. */ - chdir("/"); - - /* ignore SIGPIPE */ - signal(SIGPIPE, SIG_IGN); - - /* Get a connection, either from inetd or a listening TCP socket */ - if (inetd_flag) { - server_accept_inetd(&sock_in, &sock_out); - - if ((options.protocol & SSH_PROTO_1) && - sensitive_data.server_key == NULL) - generate_ephemeral_server_key(); - } else { - server_listen(); - - if (options.protocol & SSH_PROTO_1) - generate_ephemeral_server_key(); - - signal(SIGHUP, sighup_handler); - signal(SIGCHLD, main_sigchld_handler); - signal(SIGTERM, sigterm_handler); - signal(SIGQUIT, sigterm_handler); - - /* - * Write out the pid file after the sigterm handler - * is setup and the listen sockets are bound - */ - if (!debug_flag) { - FILE *f = fopen(options.pid_file, "w"); - - if (f == NULL) { - error("Couldn't create pid file \"%s\": %s", - options.pid_file, strerror(errno)); - } else { - fprintf(f, "%ld\n", (long) getpid()); - fclose(f); - } - } - - /* 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. */ - setproctitle("%s", "[accepted]"); - - /* - * Create a new session and process group since the 4.4BSD - * setlogin() affects the entire process group. We don't - * want the child to be able to affect the parent. - */ -#if !defined(SSHD_ACQUIRES_CTTY) - /* - * If setsid is called, on some platforms sshd will later acquire a - * controlling terminal which will result in "could not set - * controlling tty" errors. - */ - if (!debug_flag && !inetd_flag && setsid() < 0) - error("setsid: %.100s", strerror(errno)); -#endif - - if (rexec_flag) { - int fd; - - debug("rexec start in %d out %d newsock %d pipe %d sock %d", - sock_in, sock_out, newsock, startup_pipe, config_s[0]); - dup2(newsock, STDIN_FILENO); - dup2(STDIN_FILENO, STDOUT_FILENO); - if (startup_pipe == -1) - close(REEXEC_STARTUP_PIPE_FD); - else - dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); - - dup2(config_s[1], REEXEC_CONFIG_PASS_FD); - close(config_s[1]); - if (startup_pipe != -1) - close(startup_pipe); - - execv(rexec_argv[0], rexec_argv); - - /* Reexec has failed, fall back and continue */ - error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); - recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); - log_init(__progname, options.log_level, - options.log_facility, log_stderr); - - /* Clean up fds */ - startup_pipe = REEXEC_STARTUP_PIPE_FD; - close(config_s[1]); - close(REEXEC_CONFIG_PASS_FD); - newsock = sock_out = sock_in = dup(STDIN_FILENO); - if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { - dup2(fd, STDIN_FILENO); - dup2(fd, STDOUT_FILENO); - if (fd > STDERR_FILENO) - close(fd); - } - debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", - sock_in, sock_out, newsock, startup_pipe, config_s[0]); - } - - /* - * Disable the key regeneration alarm. We will not regenerate the - * key since we are no longer in a position to give it to anyone. We - * will not restart on SIGHUP since it no longer makes sense. - */ - alarm(0); - signal(SIGALRM, SIG_DFL); - signal(SIGHUP, SIG_DFL); - signal(SIGTERM, SIG_DFL); - signal(SIGQUIT, SIG_DFL); - signal(SIGCHLD, SIG_DFL); - signal(SIGINT, SIG_DFL); - - /* - * Register our connection. This turns encryption off because we do - * not have a key. - */ - packet_set_connection(sock_in, sock_out); - packet_set_server(); - - /* Set SO_KEEPALIVE if requested. */ - if (options.tcp_keep_alive && packet_connection_is_on_socket() && - setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) - error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); - - if ((remote_port = get_remote_port()) < 0) { - debug("get_remote_port failed"); - cleanup_exit(255); - } - - /* - * We use get_canonical_hostname with usedns = 0 instead of - * get_remote_ipaddr here so IP options will be checked. - */ - (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); -#endif -#ifdef LIBWRAP - /* Check whether logins are denied from this host. */ - if (packet_connection_is_on_socket()) { - struct request_info req; - - request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); - fromhost(&req); - - if (!hosts_access(&req)) { - debug("Connection refused by tcp wrapper"); - refuse(&req); - /* NOTREACHED */ - fatal("libwrap refuse returns"); - } - } -#endif /* LIBWRAP */ - - /* Log the connection. */ - verbose("Connection from %.500s port %d", remote_ip, remote_port); - - /* - * We don't want to listen forever unless the other side - * successfully authenticates itself. So we set up an alarm which is - * cleared after successful authentication. A limit of zero - * indicates no limit. Note that we don't set the alarm in debugging - * mode; it is just annoying to have the server exit just when you - * are about to discover the bug. - */ - signal(SIGALRM, grace_alarm_handler); - if (!debug_flag) - alarm(options.login_grace_time); - - sshd_exchange_identification(sock_in, sock_out); - - packet_set_nonblocking(); - - /* allocate authentication context */ - authctxt = xcalloc(1, sizeof(*authctxt)); - - authctxt->loginmsg = &loginmsg; - - /* XXX global for cleanup, access from other modules */ - the_authctxt = authctxt; - - /* prepare buffer to collect messages to display to user after login */ - buffer_init(&loginmsg); - - if (use_privsep) - if (privsep_preauth(authctxt) == 1) - goto authenticated; - - /* perform the key exchange */ - /* authenticate user and start session */ - if (compat20) { - do_ssh2_kex(); - do_authentication2(authctxt); - } else { - do_ssh1_kex(); - do_authentication(authctxt); - } - /* - * If we use privilege separation, the unprivileged child transfers - * the current keystate and exits - */ - if (use_privsep) { - mm_send_keystate(pmonitor); - exit(0); - } - - authenticated: - /* - * Cancel the alarm we set to limit the time taken for - * authentication. - */ - alarm(0); - signal(SIGALRM, SIG_DFL); - authctxt->authenticated = 1; - if (startup_pipe != -1) { - close(startup_pipe); - startup_pipe = -1; - } - -#ifdef SSH_AUDIT_EVENTS - audit_event(SSH_AUTH_SUCCESS); -#endif - - /* - * In privilege separation, we fork another child and prepare - * file descriptor passing. - */ - if (use_privsep) { - privsep_postauth(authctxt); - /* the monitor process [priv] will not return */ - if (!compat20) - destroy_sensitive_data(); - } - - /* Start session. */ - do_authenticated(authctxt); - - /* The connection has been terminated. */ - verbose("Closing connection to %.100s", remote_ip); - -#ifdef USE_PAM - if (options.use_pam) - finish_pam(); -#endif /* USE_PAM */ - -#ifdef SSH_AUDIT_EVENTS - PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); -#endif - - packet_close(); - - if (use_privsep) - mm_terminate(); - - exit(0); -} - -/* - * Decrypt session_key_int using our private server key and private host key - * (key with larger modulus first). - */ -int -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) { - /* 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", - get_remote_ipaddr(), - BN_num_bits(sensitive_data.server_key->rsa->n), - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), - SSH_KEY_BITS_RESERVED); - } - if (rsa_private_decrypt(session_key_int, session_key_int, - sensitive_data.server_key->rsa) <= 0) - rsafail++; - if (rsa_private_decrypt(session_key_int, session_key_int, - sensitive_data.ssh1_host_key->rsa) <= 0) - rsafail++; - } 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", - get_remote_ipaddr(), - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), - BN_num_bits(sensitive_data.server_key->rsa->n), - SSH_KEY_BITS_RESERVED); - } - if (rsa_private_decrypt(session_key_int, session_key_int, - sensitive_data.ssh1_host_key->rsa) < 0) - rsafail++; - if (rsa_private_decrypt(session_key_int, session_key_int, - sensitive_data.server_key->rsa) < 0) - rsafail++; - } - return (rsafail); -} -/* - * SSH1 key exchange - */ -static void -do_ssh1_kex(void) -{ - int i, len; - int rsafail = 0; - BIGNUM *session_key_int; - u_char session_key[SSH_SESSION_KEY_LENGTH]; - u_char cookie[8]; - u_int cipher_type, auth_mask, protocol_flags; - u_int32_t rnd = 0; - - /* - * Generate check bytes that the client must send back in the user - * packet in order for it to be accepted; this is used to defy ip - * spoofing attacks. Note that this only works against somebody - * doing IP spoofing from a remote machine; any machine on the local - * network can still see outgoing packets and catch the random - * cookie. This only affects rhosts authentication, and this is one - * of the reasons why it is inherently insecure. - */ - for (i = 0; i < 8; i++) { - if (i % 4 == 0) - rnd = arc4random(); - cookie[i] = rnd & 0xff; - rnd >>= 8; - } - - /* - * Send our public key. We include in the packet 64 bits of random - * data that must be matched in the reply in order to prevent IP - * spoofing. - */ - packet_start(SSH_SMSG_PUBLIC_KEY); - for (i = 0; i < 8; i++) - packet_put_char(cookie[i]); - - /* Store our public server RSA key. */ - packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); - packet_put_bignum(sensitive_data.server_key->rsa->e); - packet_put_bignum(sensitive_data.server_key->rsa->n); - - /* Store our public host RSA key. */ - packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); - packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); - packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); - - /* Put protocol flags. */ - packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); - - /* Declare which ciphers we support. */ - packet_put_int(cipher_mask_ssh1(0)); - - /* Declare supported authentication types. */ - auth_mask = 0; - if (options.rhosts_rsa_authentication) - auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; - if (options.rsa_authentication) - auth_mask |= 1 << SSH_AUTH_RSA; - if (options.challenge_response_authentication == 1) - auth_mask |= 1 << SSH_AUTH_TIS; - if (options.password_authentication) - auth_mask |= 1 << SSH_AUTH_PASSWORD; - packet_put_int(auth_mask); - - /* Send the packet and wait for it to be sent. */ - packet_send(); - packet_write_wait(); - - debug("Sent %d bit server key and %d bit host key.", - BN_num_bits(sensitive_data.server_key->rsa->n), - BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); - - /* Read clients reply (cipher type and session key). */ - packet_read_expect(SSH_CMSG_SESSION_KEY); - - /* Get cipher type and check whether we accept this. */ - cipher_type = packet_get_char(); - - if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) - packet_disconnect("Warning: client selects unsupported cipher."); - - /* Get check bytes from the packet. These must match those we - sent earlier with the public key packet. */ - for (i = 0; i < 8; i++) - if (cookie[i] != packet_get_char()) - packet_disconnect("IP Spoofing check bytes do not match."); - - debug("Encryption type: %.200s", cipher_name(cipher_type)); - - /* Get the encrypted integer. */ - if ((session_key_int = BN_new()) == NULL) - fatal("do_ssh1_kex: BN_new failed"); - packet_get_bignum(session_key_int); - - protocol_flags = packet_get_int(); - packet_set_protocol_flags(protocol_flags); - packet_check_eom(); - - /* Decrypt session_key_int using host/server keys */ - rsafail = PRIVSEP(ssh1_session_key(session_key_int)); - - /* - * Extract session key from the decrypted integer. The key is in the - * least significant 256 bits of the integer; the first byte of the - * key is in the highest bits. - */ - if (!rsafail) { - (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_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++; - } else { - memset(session_key, 0, sizeof(session_key)); - BN_bn2bin(session_key_int, - session_key + sizeof(session_key) - len); - - derive_ssh1_session_id( - sensitive_data.ssh1_host_key->rsa->n, - sensitive_data.server_key->rsa->n, - cookie, session_id); - /* - * Xor the first 16 bytes of the session key with the - * session id. - */ - for (i = 0; i < 16; i++) - session_key[i] ^= session_id[i]; - } - } - if (rsafail) { - int bytes = BN_num_bytes(session_key_int); - u_char *buf = xmalloc(bytes); - MD5_CTX md; - - logit("do_connection: generating a fake encryption key"); - BN_bn2bin(session_key_int, buf); - MD5_Init(&md); - MD5_Update(&md, buf, bytes); - MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); - MD5_Final(session_key, &md); - MD5_Init(&md); - MD5_Update(&md, session_key, 16); - MD5_Update(&md, buf, bytes); - MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); - MD5_Final(session_key + 16, &md); - memset(buf, 0, bytes); - xfree(buf); - for (i = 0; i < 16; i++) - session_id[i] = session_key[i] ^ session_key[i + 16]; - } - /* Destroy the private and public keys. No longer. */ - destroy_sensitive_data(); - - if (use_privsep) - mm_ssh1_session_id(session_id); - - /* Destroy the decrypted integer. It is no longer needed. */ - BN_clear_free(session_key_int); - - /* Set the session key. From this on all communications will be encrypted. */ - packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); - - /* Destroy our copy of the session key. It is no longer needed. */ - memset(session_key, 0, sizeof(session_key)); - - debug("Received session key; encryption turned on."); - - /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ - packet_start(SSH_SMSG_SUCCESS); - packet_send(); - packet_write_wait(); -} - -/* - * SSH2 key exchange: diffie-hellman-group1-sha1 - */ -static void -do_ssh2_kex(void) -{ - Kex *kex; - - if (options.ciphers != NULL) { - myproposal[PROPOSAL_ENC_ALGS_CTOS] = - myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; - } - myproposal[PROPOSAL_ENC_ALGS_CTOS] = - compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); - myproposal[PROPOSAL_ENC_ALGS_STOC] = - compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); - - if (options.macs != NULL) { - myproposal[PROPOSAL_MAC_ALGS_CTOS] = - myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; - } - if (options.compression == COMP_NONE) { - myproposal[PROPOSAL_COMP_ALGS_CTOS] = - myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; - } else if (options.compression == COMP_DELAYED) { - 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 */ - 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; - 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; - - xxx_kex = kex; - - dispatch_run(DISPATCH_BLOCK, &kex->done, kex); - - session_id2 = kex->session_id; - session_id2_len = kex->session_id_len; - -#ifdef DEBUG_KEXDH - /* send 1st encrypted/maced/compressed message */ - packet_start(SSH2_MSG_IGNORE); - packet_put_cstring("markus"); - packet_send(); - packet_write_wait(); -#endif - debug("KEX done"); -} - -/* server specific fatal cleanup */ -void -cleanup_exit(int i) -{ - if (the_authctxt) - do_cleanup(the_authctxt); -#ifdef SSH_AUDIT_EVENTS - /* done after do_cleanup so it can cancel the PAM auth 'thread' */ - if (!use_privsep || mm_is_monitor()) - audit_event(SSH_CONNECTION_ABANDON); -#endif - _exit(i); -} |
