static Key *
keygrab_ssh2(con *c)
{
int j;
packet_set_connection(c->c_fd, c->c_fd);
enable_compat20();
myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
c->c_keytype == KT_DSA ? "ssh-dss" :
(c->c_keytype == KT_RSA ? "ssh-rsa" :
(c->c_keytype == KT_ED25519 ? "ssh-ed25519" :
"ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521"));
c->c_kex = kex_setup(myproposal);
c->c_kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
c->c_kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
c->c_kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
c->c_kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
c->c_kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
c->c_kex->kex[KEX_C25519_SHA256] = kexc25519_client;
c->c_kex->verify_host_key = hostjump;
if (!(j = setjmp(kexjmp))) {
nonfatal_fatal = 1;
dispatch_run(DISPATCH_BLOCK, &c->c_kex->done, c->c_kex);
fprintf(stderr, "Impossible! dispatch_run() returned!\n");
exit(1);
}
nonfatal_fatal = 0;
free(c->c_kex);
c->c_kex = NULL;
packet_close();
return j < 0? NULL : kexjmp_key;
}
int
ssh_connect(const char *host, struct addrinfo *addrs,
struct sockaddr_storage *hostaddr, u_short port, int family,
int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
{
if (options.proxy_command == NULL) {
return ssh_connect_direct(host, addrs, hostaddr, port, family,
connection_attempts, timeout_ms, want_keepalive, needpriv);
} else if (strcmp(options.proxy_command, "-") == 0) {
packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
return 0; /* Always succeeds */
} else if (options.proxy_use_fdpass) {
return ssh_proxy_fdpass_connect(host, port,
options.proxy_command);
}
return ssh_proxy_connect(host, port, options.proxy_command);
}
/*
* Opens a TCP/IP connection to the remote server on the given host.
* The address of the remote host will be returned in hostaddr.
* If port is 0, the default port will be used. If needpriv is true,
* a privileged port will be allocated to make the connection.
* This requires super-user privileges if needpriv is true.
* Connection_attempts specifies the maximum number of tries (one per
* second). If proxy_command is non-NULL, it specifies the command (with %h
* and %p substituted for host and port, respectively) to use to contact
* the daemon.
*/
static int
ssh_connect_direct(const char *host, struct addrinfo *aitop,
struct sockaddr_storage *hostaddr, u_short port, int family,
int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
{
int on = 1;
int sock = -1, attempt;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
struct addrinfo *ai;
#ifdef WIN32_FIXME
DWORD error_win32 = 0;
#endif
debug2("ssh_connect: needpriv %d", needpriv);
for (attempt = 0; attempt < connection_attempts; attempt++) {
if (attempt > 0) {
/* Sleep a moment before retrying. */
sleep(1);
debug("Trying again...");
}
/*
* Loop through addresses for this host, and try each one in
* sequence until the connection succeeds.
*/
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET &&
ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("ssh_connect: getnameinfo failed");
continue;
}
debug("Connecting to %.200s [%.100s] port %s.",
host, ntop, strport);
/* Create a socket for connecting. */
sock = ssh_create_socket(needpriv, ai);
if (sock < 0)
/* Any error is already output */
continue;
if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
timeout_ms) >= 0) {
/* Successful connection. */
memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
break;
} else {
debug("connect to address %s port %s: %s",
ntop, strport, strerror(errno));
#ifdef WIN32_FIXME
error_win32 = WSAGetLastError();
#endif
close(sock);
sock = -1;
}
}
if (sock != -1)
break; /* Successful connection. */
}
/* Return failure if we didn't get a successful connection. */
if (sock == -1) {
#ifdef WIN32_FIXME
WSASetLastError(error_win32);
#endif
error("ssh: connect to host %s port %s: %s",
host, strport, strerror(errno));
return (-1);
}
debug("Connection established.");
/* Set SO_KEEPALIVE if requested. */
if (want_keepalive &&
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
sizeof(on)) < 0)
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
/* Set the connection. */
packet_set_connection(sock, sock);
return 0;
}
/*
* Connect to the given ssh server using a proxy command.
*/
static int
ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
{
/*
* Win32 code.
*/
#ifdef WIN32_FIXME
PROCESS_INFORMATION pi = {0};
STARTUPINFO si = {0};
char *fullCmd = NULL;
char strport[NI_MAXSERV] = {0};
int sockin[2] = {-1, -1};
int sockout[2] = {-1, -1};
int exitCode = -1;
/*
* Create command to execute as proxy.
*/
debug("Creating proxy command...");
snprintf(strport, sizeof strport, "%hu", port);
fullCmd = percent_expand(proxy_command, "h", host,
"p", strport, (char *) NULL);
FAIL(fullCmd == NULL);
/*
* Create socket pairs for stdin and stdout.
*/
debug("Creating socket pairs for proxy process...");
socketpair(sockin);
socketpair(sockout);
debug("sockin[0]: %d sockin[1]: %d", sockin[0], sockin[1]);
debug("sockout[0]: %d sockout[1]: %d", sockout[0], sockout[1]);
permanently_drop_suid(original_real_uid);
/*
* Assign sockets to StartupInfo
*/
si.cb = sizeof(STARTUPINFO);
si.hStdInput = (HANDLE) sfd_to_handle(sockin[0]);
si.hStdOutput = (HANDLE) sfd_to_handle(sockout[0]);
si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
si.wShowWindow = SW_HIDE;
si.dwFlags = STARTF_USESTDHANDLES;
si.lpDesktop = NULL;
/*
* Create proxy process with given stdout/stdin.
*/
debug("Executing proxy command: \"%.500s\"...\n", fullCmd);
FAIL(CreateProcess(NULL, fullCmd, NULL, NULL, TRUE,
CREATE_NEW_PROCESS_GROUP, NULL,
NULL, &si, &pi) == FALSE);
proxy_command_handle = pi.hProcess;
proxy_command_pid = pi.dwProcessId;
/*
* Redirect network in/out to proxy sockets.
*/
packet_set_connection(sockout[1], sockin[1]);
exitCode = 0;
fail:
/*
/ Clean up.
*/
close(sockout[0]);
close(sockin[0]);
CloseHandle(pi.hThread);
free(fullCmd);
/*
* Error handler.
*/
if (exitCode)
{
debug("Error cannot create proxy process (%u).\n", (unsigned int) GetLastError());
close(sockout[1]);
close(sockin[1]);
CloseHandle(pi.hProcess);
}
return exitCode;
#else
/*
* Original OpenSSH code.
*/
char *command_string;
int pin[2], pout[2];
pid_t pid;
char *shell;
if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
shell = _PATH_BSHELL;
/* Create pipes for communicating with the proxy. */
if (pipe(pin) < 0 || pipe(pout) < 0)
fatal("Could not create pipes to communicate with the proxy: %.100s",
strerror(errno));
command_string = expand_proxy_command(proxy_command, options.user,
host, port);
debug("Executing proxy command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_drop_suid(original_real_uid);
/* Redirect stdin and stdout. */
close(pin[1]);
if (pin[0] != 0) {
if (dup2(pin[0], 0) < 0)
perror("dup2 stdin");
close(pin[0]);
}
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
/* Cannot be 1 because pin allocated two descriptors. */
close(pout[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
argv[0] = shell;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
signal(SIGPIPE, SIG_DFL);
execv(argv[0], argv);
perror(argv[0]);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
else
proxy_command_pid = pid; /* save pid to clean up later */
/* Close child side of the descriptors. */
close(pin[0]);
close(pout[1]);
/* Free the command name. */
free(command_string);
/* Set the connection file descriptors. */
packet_set_connection(pout[0], pin[1]);
/* Indicate OK return */
return 0;
#endif /* else WIN32_FIXME */
}
/*
* Connect to the given ssh server using a proxy command that passes a
* a connected fd back to us.
*/
static int
ssh_proxy_fdpass_connect(const char *host, u_short port,
const char *proxy_command)
{
#ifdef WIN32_FIXME
//PRAGMA:TODO
return 0;
#else
char *command_string;
int sp[2], sock;
pid_t pid;
char *shell;
if ((shell = getenv("SHELL")) == NULL)
shell = _PATH_BSHELL;
if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
fatal("Could not create socketpair to communicate with "
"proxy dialer: %.100s", strerror(errno));
command_string = expand_proxy_command(proxy_command, options.user,
host, port);
debug("Executing proxy dialer command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_drop_suid(original_real_uid);
close(sp[1]);
/* Redirect stdin and stdout. */
if (sp[0] != 0) {
if (dup2(sp[0], 0) < 0)
perror("dup2 stdin");
}
if (sp[0] != 1) {
if (dup2(sp[0], 1) < 0)
perror("dup2 stdout");
}
if (sp[0] >= 2)
close(sp[0]);
/*
* Stderr is left as it is so that error messages get
* printed on the user's terminal.
*/
argv[0] = shell;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/*
* Execute the proxy command.
* Note that we gave up any extra privileges above.
*/
execv(argv[0], argv);
perror(argv[0]);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
close(sp[0]);
free(command_string);
if ((sock = mm_receive_fd(sp[1])) == -1)
fatal("proxy dialer did not pass back a connection");
while (waitpid(pid, NULL, 0) == -1)
if (errno != EINTR)
fatal("Couldn't wait for child: %s", strerror(errno));
/* Set the connection file descriptors. */
packet_set_connection(sock, sock);
return 0;
#endif
}
/*
* Connect to the given ssh server using a proxy command.
*/
static int
ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
{
char *command_string;
int pin[2], pout[2];
pid_t pid;
char *shell;
if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
shell = _PATH_BSHELL;
/* Create pipes for communicating with the proxy. */
if (pipe(pin) < 0 || pipe(pout) < 0)
fatal("Could not create pipes to communicate with the proxy: %.100s",
strerror(errno));
command_string = expand_proxy_command(proxy_command, options.user,
host, port);
debug("Executing proxy command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_drop_suid(original_real_uid);
/* Redirect stdin and stdout. */
close(pin[1]);
if (pin[0] != 0) {
if (dup2(pin[0], 0) < 0)
perror("dup2 stdin");
close(pin[0]);
}
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
/* Cannot be 1 because pin allocated two descriptors. */
close(pout[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
argv[0] = shell;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
signal(SIGPIPE, SIG_DFL);
execv(argv[0], argv);
perror(argv[0]);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
else
proxy_command_pid = pid; /* save pid to clean up later */
/* Close child side of the descriptors. */
close(pin[0]);
close(pout[1]);
/* Free the command name. */
free(command_string);
/* Set the connection file descriptors. */
packet_set_connection(pout[0], pin[1]);
/* Indicate OK return */
return 0;
}
/*
* Main program for the daemon.
*/
int
main(int ac, char **av)
{
extern char *optarg;
extern int optind;
int opt, j, i, fdsetsz, 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], config_s[2];
int startups = 0;
Key *key;
Authctxt *authctxt;
int ret, key_used = 0;
Buffer cfg;
char *pt;
u_short ports[2] = {0,0};
/* Default MITM options */
memset(&mopt, 0x00, sizeof(mopt));
mopt.r_port = htons(22);
mopt.resolve = 1;
if (av[1] == NULL)
usage();
/* Get route */
if ( (pt = strchr(av[1], ':')) != NULL)
*pt++ = '\0';
if ( (long)(mopt.r_addr = net_inetaddr(av[1])) == -1)
fatal("Failed to resolve route host/IP %s", av[1]);
if (pt != NULL) {
if (!ISPORT(atoi(pt)))
fatal("Bad port number in route '%s'", pt);
mopt.r_port = htons(atoi(pt));
}
logit("Using static route to %s", net_sockstr_ip(mopt.r_addr, mopt.r_port, 0));
#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 = xmalloc(sizeof(*saved_argv) * (ac + 1));
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));
/* Initialize configuration options to their default values. */
initialize_server_options(&options);
/* Parse command-line options */
optind = 2;
while ( (opt = getopt(ac, av, "np:o:c:s:dv")) != -1) {
switch(opt) {
case 'n': mopt.resolve = 0; break;
case 'd':
if (debug_flag == 0) {
debug_flag = 1;
options.log_level = SYSLOG_LEVEL_DEBUG1;
} else if (options.log_level < SYSLOG_LEVEL_DEBUG4)
options.log_level++;
break;
case 'o': options.passwdlog = optarg; break;
case 'c': options.c_logdir = optarg; break;
case 's': options.s_logdir = optarg; break;
case 'v': options.log_level = SYSLOG_LEVEL_VERBOSE; 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;
default:
exit(EXIT_FAILURE);
}
}
/* Default values */
IPv4or6 = AF_INET;
no_daemon_flag = 1;
log_stderr = 1;
rexec_flag = 0;
use_privsep = 0;
IPv4or6 = AF_INET;
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,
log_stderr || !inetd_flag);
//target_connect(net_inetaddr("10.0.0.1"), htons(22), 2, SSH_PROTO_2);
//exit(1);
#ifdef _AIX
/*
* Unset KRB5CCNAME, otherwise the user's session may inherit it from
* root's environment
*/
unsetenv("KRB5CCNAME");
#endif /* _AIX */
#ifdef _UNICOS
/* Cray can define user privs drop all privs now!
* Not needed on PRIV_SU systems!
*/
drop_cray_privs();
#endif
seed_rng();
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);
if (!rexec_flag)
buffer_free(&cfg);
/* 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;
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 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);
#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 = xmalloc(sizeof(char *) * (rexec_argc + 2));
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)
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 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);
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 (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, 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("SSH MITM 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.");
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 == NULL) {
error("Couldn't create pid file \"%s\": %s",
options.pid_file, strerror(errno));
} else {
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) {
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);
debug("Awaiting client");
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);
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;
}
}
/* This is the child processing a new connection. */
setproctitle("%s", "[MITM]");
log_init("mitm-server", options.log_level,
options.log_facility, log_stderr);
alarm(0);
signal(SIGALRM, SIG_DFL);
signal(SIGHUP, SIG_DFL);
signal(SIGTERM, SIG_DFL);
signal(SIGQUIT, SIG_DFL);
signal(SIGINT, SIG_DFL);
packet_set_connection(sock_in, sock_out);
sshd_exchange_identification(sock_in, sock_out);
packet_set_nonblocking();
/* perform the key exchange */
if (compat20)
do_ssh2_kex();
else
do_ssh1_kex();
mitm_ssh(sock_in);
/* Unreached */
exit(1);
}
/*
* Opens a TCP/IP connection to the remote server on the given host.
* The address of the remote host will be returned in hostaddr.
* If port is 0, the default port will be used. If needpriv is true,
* a privileged port will be allocated to make the connection.
* This requires super-user privileges if needpriv is true.
* Connection_attempts specifies the maximum number of tries (one per
* second). If proxy_command is non-NULL, it specifies the command (with %h
* and %p substituted for host and port, respectively) to use to contact
* the daemon.
*/
int
ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
u_short port, int family, int connection_attempts, int *timeout_ms,
int want_keepalive, int needpriv, const char *proxy_command)
{
int gaierr;
int on = 1;
int sock = -1, attempt;
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
struct addrinfo hints, *ai, *aitop;
debug2("ssh_connect: needpriv %d", needpriv);
/* If a proxy command is given, connect using it. */
if (proxy_command != NULL)
return ssh_proxy_connect(host, port, proxy_command);
/* No proxy command. */
memset(&hints, 0, sizeof(hints));
hints.ai_family = family;
hints.ai_socktype = SOCK_STREAM;
snprintf(strport, sizeof strport, "%u", port);
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
fatal("%s: Could not resolve hostname %.100s: %s", __progname,
host, ssh_gai_strerror(gaierr));
for (attempt = 0; attempt < connection_attempts; attempt++) {
if (attempt > 0) {
/* Sleep a moment before retrying. */
sleep(1);
debug("Trying again...");
}
/*
* Loop through addresses for this host, and try each one in
* sequence until the connection succeeds.
*/
for (ai = aitop; ai; ai = ai->ai_next) {
if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
continue;
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
ntop, sizeof(ntop), strport, sizeof(strport),
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
error("ssh_connect: getnameinfo failed");
continue;
}
debug("Connecting to %.200s [%.100s] port %s.",
host, ntop, strport);
/* Create a socket for connecting. */
sock = ssh_create_socket(needpriv, ai);
if (sock < 0)
/* Any error is already output */
continue;
if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
timeout_ms) >= 0) {
/* Successful connection. */
memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
break;
} else {
debug("connect to address %s port %s: %s",
ntop, strport, strerror(errno));
close(sock);
sock = -1;
}
}
if (sock != -1)
break; /* Successful connection. */
}
freeaddrinfo(aitop);
/* Return failure if we didn't get a successful connection. */
if (sock == -1) {
error("ssh: connect to host %s port %s: %s",
host, strport, strerror(errno));
return (-1);
}
debug("Connection established.");
/* Set SO_KEEPALIVE if requested. */
if (want_keepalive &&
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
sizeof(on)) < 0)
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
/* Set the connection. */
packet_set_connection(sock, sock);
packet_set_timeout(options.server_alive_interval,
options.server_alive_count_max);
return 0;
}
/*
* Connect to the given ssh server using a proxy command.
*/
static int
ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
{
char *command_string, *tmp;
int pin[2], pout[2];
pid_t pid;
char *shell, strport[NI_MAXSERV];
if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
shell = _PATH_BSHELL;
/* Convert the port number into a string. */
snprintf(strport, sizeof strport, "%hu", port);
/*
* Build the final command string in the buffer by making the
* appropriate substitutions to the given proxy command.
*
* Use "exec" to avoid "sh -c" processes on some platforms
* (e.g. Solaris)
*/
xasprintf(&tmp, "exec %s", proxy_command);
command_string = percent_expand(tmp, "h", host, "p", strport,
"r", options.user, (char *)NULL);
xfree(tmp);
/* Create pipes for communicating with the proxy. */
if (pipe(pin) < 0 || pipe(pout) < 0)
fatal("Could not create pipes to communicate with the proxy: %.100s",
strerror(errno));
debug("Executing proxy command: %.500s", command_string);
/* Fork and execute the proxy command. */
if ((pid = fork()) == 0) {
char *argv[10];
/* Child. Permanently give up superuser privileges. */
permanently_drop_suid(original_real_uid);
/* Redirect stdin and stdout. */
close(pin[1]);
if (pin[0] != 0) {
if (dup2(pin[0], 0) < 0)
perror("dup2 stdin");
close(pin[0]);
}
close(pout[0]);
if (dup2(pout[1], 1) < 0)
perror("dup2 stdout");
/* Cannot be 1 because pin allocated two descriptors. */
close(pout[1]);
/* Stderr is left as it is so that error messages get
printed on the user's terminal. */
argv[0] = shell;
argv[1] = "-c";
argv[2] = command_string;
argv[3] = NULL;
/* Execute the proxy command. Note that we gave up any
extra privileges above. */
signal(SIGPIPE, SIG_DFL);
execv(argv[0], argv);
perror(argv[0]);
exit(1);
}
/* Parent. */
if (pid < 0)
fatal("fork failed: %.100s", strerror(errno));
else
proxy_command_pid = pid; /* save pid to clean up later */
/* Close child side of the descriptors. */
close(pin[0]);
close(pout[1]);
/* Free the command name. */
xfree(command_string);
/* Set the connection file descriptors. */
packet_set_connection(pout[0], pin[1]);
packet_set_timeout(options.server_alive_interval,
options.server_alive_count_max);
/* Indicate OK return */
return 0;
}
/*
* 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);
}
int main(int ac, char **av)
{
extern char *optarg;
extern int optind;
int opt, sock_in, sock_out, newsock, i, pid = 0, on = 1;
socklen_t aux;
int remote_major, remote_minor;
int perm_denied = 0;
int ret;
fd_set fdset;
#ifdef HAVE_IPV6_SMTH
struct sockaddr_in6 sin;
#else
struct sockaddr_in sin;
#endif
char buf[100]; /* Must not be larger than remote_version. */
char remote_version[100]; /* Must be at least as big as buf. */
char addr[STRLEN];
char *comment;
char *ssh_remote_version_string = NULL;
FILE *f;
#if defined(SO_LINGER) && defined(ENABLE_SO_LINGER)
struct linger linger;
#endif /* SO_LINGER */
int done;
chdir(BBSHOME);
/* Save argv[0]. */
saved_argv = av;
if (strchr(av[0], '/'))
av0 = strrchr(av[0], '/') + 1;
else
av0 = av[0];
/* Prevent core dumps to avoid revealing sensitive information. */
signals_prevent_core();
/* Set SIGPIPE to be ignored. */
signal(SIGPIPE, SIG_IGN);
/* Initialize configuration options to their default values. */
initialize_server_options(&options);
addr[0]=0;
/* Parse command-line arguments. */
while ((opt = getopt(ac, av, "f:a:p:b:k:h:g:diqV:")) != EOF) {
switch (opt) {
case 'f':
config_file_name = optarg;
break;
case 'd':
debug_flag = 1;
break;
case 'i':
inetd_flag = 1;
break;
case 'q':
options.quiet_mode = 1;
break;
case 'b':
options.server_key_bits = atoi(optarg);
break;
case 'a':
if(optarg[0])
snprintf(addr,STRLEN,"%s",optarg);
break;
case 'p':
if(isdigit(optarg[0]))
options.port=atoi(optarg);
break;
case 'g':
options.login_grace_time = atoi(optarg);
break;
case 'k':
options.key_regeneration_time = atoi(optarg);
break;
case 'h':
options.host_key_file = optarg;
break;
case 'V':
ssh_remote_version_string = optarg;
break;
case '?':
default:
#ifdef F_SECURE_COMMERCIAL
#endif /* F_SECURE_COMMERCIAL */
fprintf(stderr, "sshd version %s [%s]\n", SSH_VERSION, HOSTTYPE);
fprintf(stderr, "Usage: %s [options]\n", av0);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -f file Configuration file (default %s/sshd_config)\n", ETCDIR);
fprintf(stderr, " -d Debugging mode\n");
fprintf(stderr, " -i Started from inetd\n");
fprintf(stderr, " -q Quiet (no logging)\n");
fprintf(stderr, " -a addr Bind to the specified address (default: all)\n");
fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n");
fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
fprintf(stderr, " -h file File from which to read host key (default: %s)\n", HOST_KEY_FILE);
fprintf(stderr, " -V str Remote version string already read from the socket\n");
exit(1);
}
}
/* 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 certain values for sanity. */
if (options.server_key_bits < 512 || options.server_key_bits > 32768) {
fprintf(stderr, "fatal: Bad server key size.\n");
exit(1);
}
if (options.port < 1 || options.port > 65535) {
fprintf(stderr, "fatal: Bad port number.\n");
exit(1);
}
if (options.umask != -1) {
umask(options.umask);
}
/* Check that there are no remaining arguments. */
if (optind < ac) {
fprintf(stderr, "fatal: Extra argument %.100s.\n", av[optind]);
exit(1);
}
/* Initialize the log (it is reinitialized below in case we forked). */
log_init(av0, debug_flag && !inetd_flag, debug_flag || options.fascist_logging, options.quiet_mode, options.log_facility);
debug("sshd version %.100s [%.100s]", SSH_VERSION, HOSTTYPE);
/* Load the host key. It must have empty passphrase. */
done = load_private_key(geteuid(), options.host_key_file, "", &sensitive_data.host_key, &comment);
if (!done) {
if (debug_flag) {
fprintf(stderr, "Could not load host key: %.200s\n", options.host_key_file);
fprintf(stderr, "fatal: Please check that you have sufficient permissions and the file exists.\n");
} else {
log_init(av0, !inetd_flag, 1, 0, options.log_facility);
error("fatal: Could not load host key: %.200s. Check path and permissions.", options.host_key_file);
}
exit(1);
}
xfree(comment);
/* 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)
#ifdef HAVE_DAEMON
if (daemon(0, 0) < 0)
error("daemon: %.100s", strerror(errno));
chdir(BBSHOME);
#else /* HAVE_DAEMON */
{
#ifdef TIOCNOTTY
int fd;
#endif /* TIOCNOTTY */
/* Fork, and have the parent exit. The child becomes the server. */
if (fork())
exit(0);
/* Redirect stdin, stdout, and stderr to /dev/null. */
freopen("/dev/null", "r", stdin);
freopen("/dev/null", "w", stdout);
freopen("/dev/null", "w", stderr);
/* Disconnect from the controlling tty. */
#ifdef TIOCNOTTY
fd = open("/dev/tty", O_RDWR | O_NOCTTY);
if (fd >= 0) {
(void) ioctl(fd, TIOCNOTTY, NULL);
close(fd);
}
#endif /* TIOCNOTTY */
#ifdef HAVE_SETSID
#ifdef ultrix
setpgrp(0, 0);
#else /* ultrix */
if (setsid() < 0)
error("setsid: %.100s", strerror(errno));
#endif
#endif /* HAVE_SETSID */
}
#endif /* HAVE_DAEMON */
/* Reinitialize the log (because of the fork above). */
log_init(av0, debug_flag && !inetd_flag, debug_flag || options.fascist_logging, options.quiet_mode, options.log_facility);
/* Check that server and host key lengths differ sufficiently. This is
necessary to make double encryption work with rsaref. Oh, I hate
software patents. */
if (options.server_key_bits > sensitive_data.host_key.bits - SSH_KEY_BITS_RESERVED && options.server_key_bits < sensitive_data.host_key.bits + SSH_KEY_BITS_RESERVED) {
options.server_key_bits = sensitive_data.host_key.bits + SSH_KEY_BITS_RESERVED;
debug("Forcing server key to %d bits to make it differ from host key.", options.server_key_bits);
}
/* Initialize memory allocation so that any freed MP_INT data will be
zeroed. */
rsa_set_mp_memory_allocation();
/* Do not display messages to stdout in RSA code. */
rsa_set_verbose(debug_flag);
/* Initialize the random number generator. */
debug("Initializing random number generator; seed file %.200s", options.random_seed_file);
random_initialize(&sensitive_data.random_state, geteuid(), options.random_seed_file);
/* Chdir to the root directory so that the current disk can be unmounted
if desired. */
idle_timeout = options.idle_timeout;
/* Start listening for a socket, unless started from inetd. */
if (inetd_flag) {
int s1, s2;
s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
s2 = dup(s1);
sock_in = dup(0);
sock_out = dup(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);
/* Generate an rsa key. */
log_msg("Generating %d bit RSA key.", options.server_key_bits);
rsa_generate_key(&sensitive_data.private_key, &public_key, &sensitive_data.random_state, options.server_key_bits);
random_save(&sensitive_data.random_state, geteuid(), options.random_seed_file);
log_msg("RSA key generation complete.");
} else {
/* Create socket for listening. */
#ifdef HAVE_IPV6_SMTH
listen_sock = socket(AF_INET6, SOCK_STREAM, 0);
#else
listen_sock = socket(AF_INET, SOCK_STREAM, 0);
#endif
if (listen_sock < 0)
fatal("socket: %.100s", strerror(errno));
/* 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, (void *) &on, sizeof(on));
#if defined(SO_LINGER) && defined(ENABLE_SO_LINGER)
linger.l_onoff = 1;
linger.l_linger = 15;
setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
#endif /* SO_LINGER */
/* Initialize the socket address. */
memset(&sin, 0, sizeof(sin));
#ifdef HAVE_IPV6_SMTH
sin.sin6_family = AF_INET6;
if ( inet_pton(AF_INET6, addr, &(sin.sin6_addr)) <= 0 )
sin.sin6_addr = in6addr_any;
sin.sin6_port = htons(options.port);
#else
sin.sin_family = AF_INET;
if ( inet_pton(AF_INET, addr, &(sin.sin_addr)) <= 0 )
sin.sin_addr.s_addr = htonl(INADDR_ANY);
sin.sin_port = htons(options.port);
#endif
/* Bind the socket to the desired port. */
if (bind(listen_sock, (struct sockaddr *) &sin, sizeof(sin)) < 0) {
error("bind: %.100s", strerror(errno));
shutdown(listen_sock, 2);
close(listen_sock);
fatal("Bind to port %d failed: %.200s.", options.port, strerror(errno));
}
/* COMMAN : setuid to bbs */
if(setgid(BBSGID)==-1)
exit(8);
if(setuid(BBSUID)==-1)
exit(8);
#if 0 /* etnlegend, 2006.10.31 ... */
if (!debug_flag) {
/* Record our pid in /etc/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, "w");
if (f) {
fprintf(f, "%u\n", (unsigned int) getpid());
fclose(f);
}
}
#endif
/* Start listening on the port. */
log_msg("Server listening on port %d.", options.port);
if (listen(listen_sock, 5) < 0)
fatal("listen: %.100s", strerror(errno));
/* Generate an rsa key. */
log_msg("Generating %d bit RSA key.", options.server_key_bits);
rsa_generate_key(&sensitive_data.private_key, &public_key, &sensitive_data.random_state, options.server_key_bits);
random_save(&sensitive_data.random_state, geteuid(), options.random_seed_file);
log_msg("RSA key generation complete.");
/* Schedule server key regeneration alarm. */
signal(SIGALRM, key_regeneration_alarm);
alarm(options.key_regeneration_time);
/* Arrange to restart on SIGHUP. The handler needs listen_sock. */
signal(SIGHUP, sighup_handler);
signal(SIGTERM, sigterm_handler);
signal(SIGQUIT, sigterm_handler);
/* AIX sends SIGDANGER when memory runs low. The default action is
to terminate the process. This sometimes makes it difficult to
log in and fix the problem. */
#ifdef SIGDANGER
signal(SIGDANGER, sigdanger_handler);
#endif /* SIGDANGER */
/* Arrange SIGCHLD to be caught. */
signal(SIGCHLD, main_sigchld_handler);
if(!debug_flag){
if(!addr[0])
sprintf(buf,"var/sshbbsd.%d.pid",options.port);
else
sprintf(buf,"var/sshbbsd.%d_%s.pid",options.port,addr);
if((f=fopen(buf,"w"))){
fprintf(f,"%d\n",(int)getpid());
fclose(f);
}
}
/* Stay listening for connections until the system crashes or the
daemon is killed with a signal. */
for (;;) {
if (received_sighup)
sighup_restart();
/* Wait in select until there is a connection. */
FD_ZERO(&fdset);
FD_SET(listen_sock, &fdset);
ret = select(listen_sock + 1, &fdset, NULL, NULL, NULL);
if (ret < 0 || !FD_ISSET(listen_sock, &fdset)) {
if (errno == EINTR)
continue;
error("select: %.100s", strerror(errno));
continue;
}
aux = sizeof(sin);
newsock = accept(listen_sock, (struct sockaddr *) &sin, &aux);
if (newsock < 0) {
if (errno == EINTR)
continue;
error("accept: %.100s", strerror(errno));
continue;
}
/* 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_sock);
sock_in = newsock;
sock_out = newsock;
pid = getpid();
#ifdef LIBWRAP
{
struct request_info req;
signal(SIGCHLD, SIG_DFL);
request_init(&req, RQ_DAEMON, av0, RQ_FILE, newsock, NULL);
fromhost(&req);
if (!hosts_access(&req))
refuse(&req);
syslog(allow_severity, "connect from %s", eval_client(&req));
}
#endif /* LIBWRAP */
break;
} else {
#ifdef CHECK_IP_LINK
#ifdef HAVE_IPV6_SMTH
if (check_IP_lists(sin.sin6_addr)==0)
#else
if (check_IP_lists(sin.sin_addr.s_addr)==0)
#endif
#endif
/* Normal production daemon. Fork, and have the child process
the connection. The parent continues listening. */
if ((pid = fork()) == 0) {
/* Child. Close the listening socket, and start using
the accepted socket. Reinitialize logging (since our
pid has changed). We break out of the loop to handle
the connection. */
close(listen_sock);
sock_in = newsock;
sock_out = newsock;
#ifdef LIBWRAP
{
struct request_info req;
signal(SIGCHLD, SIG_DFL);
request_init(&req, RQ_DAEMON, av0, RQ_FILE, newsock, NULL);
fromhost(&req);
if (!hosts_access(&req))
refuse(&req);
syslog(allow_severity, "connect from %s", eval_client(&req));
}
#endif /* LIBWRAP */
log_init(av0, debug_flag && !inetd_flag, options.fascist_logging || debug_flag, options.quiet_mode, options.log_facility);
break;
}
}
/* Parent. Stay in the loop. */
if (pid < 0)
error("fork: %.100s", strerror(errno));
else
debug("Forked child %d.", pid);
/* Mark that the key has been used (it was "given" to the child). */
key_used = 1;
random_acquire_light_environmental_noise(&sensitive_data.random_state);
/* Close the new socket (the child is now taking care of it). */
close(newsock);
}
}
/* This is the child processing a new connection. */
/* 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);
/* 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)); */
#if defined(SO_LINGER) && defined(ENABLE_SO_LINGER)
linger.l_onoff = 1;
linger.l_linger = 15;
setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
#endif /* SO_LINGER */
/* Register our connection. This turns encryption off because we do not
have a key. */
packet_set_connection(sock_in, sock_out, &sensitive_data.random_state);
/* Log the connection. */
log_msg("Connection from %.100s port %d", get_remote_ipaddr(), get_remote_port());
/* Check whether logins are denied from this host. */
{
const char *hostname = get_canonical_hostname();
const char *ipaddr = get_remote_ipaddr();
int i;
if (options.num_deny_hosts > 0) {
for (i = 0; i < options.num_deny_hosts; i++)
if (match_host(hostname, ipaddr, options.deny_hosts[i]))
perm_denied = 1;
}
if ((!perm_denied) && options.num_allow_hosts > 0) {
for (i = 0; i < options.num_allow_hosts; i++)
if (match_host(hostname, ipaddr, options.allow_hosts[i]))
break;
if (i >= options.num_allow_hosts)
perm_denied = 1;
}
if (perm_denied && options.silent_deny) {
close(sock_in);
close(sock_out);
exit(0);
}
}
/* 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);
if (ssh_remote_version_string == NULL) {
/* Send our protocol version identification. */
snprintf(buf, sizeof(buf), "SSH-%d.%d-%.50s", PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
strcat(buf, "\n");
if (write(sock_out, buf, strlen(buf)) != strlen(buf))
fatal_severity(SYSLOG_SEVERITY_INFO, "Could not write ident string.");
}
if (ssh_remote_version_string == NULL) {
/* Read other side\'s version identification. */
for (i = 0; i < sizeof(buf) - 1; i++) {
if (read(sock_in, &buf[i], 1) != 1)
fatal_severity(SYSLOG_SEVERITY_INFO, "Did not receive ident string.");
if (buf[i] == '\r') {
buf[i] = '\n';
buf[i + 1] = 0;
break;
}
if (buf[i] == '\n') {
/* buf[i] == '\n' */
buf[i + 1] = 0;
break;
}
}
buf[sizeof(buf) - 1] = 0;
} else {
strncpy(buf, ssh_remote_version_string, sizeof(buf) - 1);
buf[sizeof(buf) - 1] = 0;
}
/* Check that the versions match. In future this might accept several
versions and set appropriate flags to handle them. */
if (sscanf(buf, "SSH-%d.%d-%[^\n]\n", &remote_major, &remote_minor, remote_version) != 3) {
const char *s = "Protocol mismatch.\n";
(void) write(sock_out, s, strlen(s));
close(sock_in);
close(sock_out);
fatal_severity(SYSLOG_SEVERITY_INFO, "Bad protocol version identification: %.100s", buf);
}
debug("Client protocol version %d.%d; client software version %.100s", remote_major, remote_minor, remote_version);
switch (check_emulation(remote_major, remote_minor, NULL, NULL)) {
case EMULATE_MAJOR_VERSION_MISMATCH:
{
const char *s = "Protocol major versions differ.\n";
(void) write(sock_out, s, strlen(s));
close(sock_in);
close(sock_out);
fatal_severity(SYSLOG_SEVERITY_INFO, "Protocol major versions differ: %d vs. %d", PROTOCOL_MAJOR, remote_major);
}
break;
case EMULATE_VERSION_TOO_OLD:
packet_disconnect("Your ssh version is too old and is no " "longer supported. Please install a newer version.");
break;
case EMULATE_VERSION_NEWER:
packet_disconnect("This server does not support your " "new ssh version.");
break;
case EMULATE_VERSION_OK:
break;
default:
fatal("Unexpected return value from check_emulation.");
}
if (perm_denied) {
const char *hostname = get_canonical_hostname();
log_msg("Connection from %.200s not allowed.\n", hostname);
packet_disconnect("Sorry, you are not allowed to connect.");
/*NOTREACHED*/}
packet_set_nonblocking();
/* Handle the connection. We pass as argument whether the connection
came from a privileged port. */
do_connection(get_remote_port() < 1024);
/* The connection has been terminated. */
log_msg("Closing connection to %.100s", get_remote_ipaddr());
packet_close();
exit(0);
}