void
read_server_config(ServerOptions *options, const char *filename)
{
int linenum, bad_options = 0;
char line[1024];
FILE *f;
debug2("read_server_config: filename %s", filename);
f = fopen(filename, "r");
if (!f) {
perror(filename);
exit(1);
}
linenum = 0;
while (fgets(line, sizeof(line), f)) {
/* Update line number counter. */
linenum++;
if (process_server_config_line(options, line, filename, linenum) != 0)
bad_options++;
}
fclose(f);
if (bad_options > 0)
fatal("%s: terminating, %d bad configuration options",
filename, bad_options);
}
void
parse_server_config(ServerOptions *options, const char *filename, Buffer *conf,
const char *user, const char *host, const char *address)
{
int active, linenum, bad_options = 0;
char *cp, *obuf, *cbuf;
debug2("%s: config %s len %d", __func__, filename, buffer_len(conf));
obuf = cbuf = xstrdup(buffer_ptr(conf));
active = user ? 0 : 1;
linenum = 1;
while ((cp = strsep(&cbuf, "\n")) != NULL) {
if (process_server_config_line(options, cp, filename,
linenum++, &active, user, host, address) != 0)
bad_options++;
}
xfree(obuf);
if (bad_options > 0)
fatal("%s: terminating, %d bad configuration options",
filename, bad_options);
}
/*
* Main program for the daemon.
*/
int
main(int ac, char **av)
{
extern char *optarg;
extern int optind;
int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
pid_t pid;
socklen_t fromlen;
fd_set *fdset;
struct sockaddr_storage from;
const char *remote_ip;
int remote_port;
FILE *f;
struct linger linger;
struct addrinfo *ai;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
int listen_sock, maxfd;
int startup_p[2];
int startups = 0;
Authctxt *authctxt;
Key *key;
int ret, key_used = 0;
#ifdef HAVE_SECUREWARE
(void)set_auth_parameters(ac, av);
#endif
__progname = get_progname(av[0]);
init_rng();
/* Save argv. */
saved_argc = ac;
saved_argv = av;
/* 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:V:u:o:dDeiqtQ46:S")) != -1) {
switch (opt) {
case '4':
IPv4or6 = AF_INET;
break;
case '6':
IPv4or6 = AF_INET6;
break;
case 'f':
config_file_name = optarg;
break;
case 'd':
if (0 == debug_flag) {
debug_flag = 1;
options.log_level = SYSLOG_LEVEL_DEBUG1;
} else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
options.log_level++;
} else {
fprintf(stderr, "Too high debugging level.\n");
exit(1);
}
break;
case 'D':
no_daemon_flag = 1;
break;
case 'e':
log_stderr = 1;
break;
case 'i':
inetd_flag = 1;
break;
case 'Q':
/* ignored */
break;
case 'q':
options.log_level = SYSLOG_LEVEL_QUIET;
break;
case 'b':
options.server_key_bits = atoi(optarg);
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 'V':
client_version_string = optarg;
/* only makes sense with inetd_flag, i.e. no listen() */
inetd_flag = 1;
break;
case 't':
test_flag = 1;
break;
case 'u':
utmp_len = atoi(optarg);
break;
case 'o':
if (process_server_config_line(&options, optarg,
"command-line", 0) != 0)
exit(1);
break;
case 'S':
protocol = IPPROTO_SCTP;
break;
case '?':
default:
usage();
break;
}
}
SSLeay_add_all_algorithms();
channel_set_af(IPv4or6);
/*
* 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,
!inetd_flag);
#ifdef _CRAY
/* Cray can define user privs drop all prives now!
* Not needed on PRIV_SU systems!
*/
drop_cray_privs();
#endif
seed_rng();
/* Read server configuration options from the configuration file. */
read_server_config(&options, config_file_name);
/* Fill in default values for those options not explicitly set. */
fill_default_server_options(&options);
/* 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_VERSION);
/* load private host keys */
sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
for (i = 0; i < options.num_host_key_files; i++)
sensitive_data.host_keys[i] = NULL;
sensitive_data.server_key = NULL;
sensitive_data.ssh1_host_key = NULL;
sensitive_data.have_ssh1_key = 0;
sensitive_data.have_ssh2_key = 0;
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) {
log("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) {
log("Disabling protocol version 2. Could not load host key");
options.protocol &= ~SSH_PROTO_2;
}
if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
log("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 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",
_PATH_PRIVSEP_CHROOT_DIR);
if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
fatal("Bad owner or mode for %s",
_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));
/* Initialize the log (it is reinitialized below in case we forked). */
if (debug_flag && !inetd_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);
/* Start listening for a socket, unless started from inetd. */
if (inetd_flag) {
int s1;
s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
dup(s1);
sock_in = dup(0);
sock_out = dup(1);
startup_pipe = -1;
/*
* 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.
*/
debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
if (options.protocol & SSH_PROTO_1)
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 (getnameinfo(ai->ai_addr, ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("getnameinfo failed");
continue;
}
/* Create socket for listening. */
listen_sock = socket(ai->ai_family, SOCK_STREAM, protocol);
if (listen_sock < 0) {
/* kernel may not support ipv6 */
verbose("socket: %.100s", strerror(errno));
continue;
}
if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
error("listen_sock O_NONBLOCK: %s", strerror(errno));
close(listen_sock);
continue;
}
/*
* Set socket options. We try to make the port
* reusable and have it close as fast as possible
* without waiting in unnecessary wait states on
* close.
*/
setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
&on, sizeof(on));
linger.l_onoff = 1;
linger.l_linger = 5;
setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
&linger, sizeof(linger));
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. */
log("Server listening on %s port %s.", ntop, strport);
if (listen(listen_sock, 5) < 0)
fatal("listen: %.100s", strerror(errno));
}
freeaddrinfo(options.listen_addrs);
if (!num_listen_socks)
fatal("Cannot bind any address.");
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(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 */
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");
if (f) {
fprintf(f, "%ld\n", (long) getpid());
fclose(f);
}
}
/* 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) {
log("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 (fcntl(newsock, F_SETFL, 0) < 0) {
error("newsock del O_NONBLOCK: %s", strerror(errno));
close(newsock);
continue;
}
if (drop_connection(startups) == 1) {
debug("drop connection #%d", startups);
close(newsock);
continue;
}
if (pipe(startup_p) == -1) {
close(newsock);
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;
startup_pipe = -1;
pid = getpid();
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);
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]);
/* 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;
}
}
/* This is the child processing a new connection. */
/*
* 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 0
/* XXX: this breaks Solaris */
if (!debug_flag && !inetd_flag && setsid() < 0)
error("setsid: %.100s", strerror(errno));
#endif
/*
* 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);
/*
* Set socket options for the connection. We want the socket to
* close as fast as possible without waiting for anything. If the
* connection is not a socket, these will do nothing.
*/
/* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
linger.l_onoff = 1;
linger.l_linger = 5;
setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger));
/* Set keepalives if requested. */
if (options.keepalives &&
setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on,
sizeof(on)) < 0)
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
/*
* Register our connection. This turns encryption off because we do
* not have a key.
*/
packet_set_connection(sock_in, sock_out);
remote_port = get_remote_port();
remote_ip = get_remote_ipaddr();
#ifdef LIBWRAP
/* Check whether logins are denied from this host. */
{
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);
/*
* Check that the connection comes from a privileged port.
* Rhosts-Authentication only makes sense from privileged
* programs. Of course, if the intruder has root access on his local
* machine, he can connect from any port. So do not use these
* authentication methods from machines that you do not trust.
*/
if (options.rhosts_authentication &&
(remote_port >= IPPORT_RESERVED ||
remote_port < IPPORT_RESERVED / 2)) {
debug("Rhosts Authentication disabled, "
"originating port %d not trusted.", remote_port);
options.rhosts_authentication = 0;
}
#if defined(KRB4) && !defined(KRB5)
if (!packet_connection_is_ipv4() &&
options.kerberos_authentication) {
debug("Kerberos Authentication disabled, only available for IPv4.");
options.kerberos_authentication = 0;
}
#endif /* KRB4 && !KRB5 */
#ifdef AFS
/* If machine has AFS, set process authentication group. */
if (k_hasafs()) {
k_setpag();
k_unlog();
}
#endif /* AFS */
packet_set_nonblocking();
if (use_privsep)
if ((authctxt = privsep_preauth()) != NULL)
goto authenticated;
/* perform the key exchange */
/* authenticate user and start session */
if (compat20) {
do_ssh2_kex();
authctxt = do_authentication2();
} else {
do_ssh1_kex();
authctxt = do_authentication();
}
/*
* If we use privilege separation, the unprivileged child transfers
* the current keystate and exits
*/
if (use_privsep) {
mm_send_keystate(pmonitor);
exit(0);
}
authenticated:
/*
* 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();
}
/* Perform session preparation. */
do_authenticated(authctxt);
/* The connection has been terminated. */
verbose("Closing connection to %.100s", remote_ip);
#ifdef USE_PAM
finish_pam();
#endif /* USE_PAM */
packet_close();
if (use_privsep)
mm_terminate();
exit(0);
}
