3005 lines
84 KiB
C
3005 lines
84 KiB
C
/*
|
|
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
* Created: Fri Mar 17 17:09:28 1995 ylo
|
|
* 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include "includes.h"
|
|
RCSID("$OpenBSD: sshd.c,v 1.94 2000/03/23 22:15:34 markus Exp $");
|
|
|
|
#include "xmalloc.h"
|
|
#include "rsa.h"
|
|
#include "ssh.h"
|
|
#include "pty.h"
|
|
#include "packet.h"
|
|
#include "buffer.h"
|
|
#include "cipher.h"
|
|
#include "mpaux.h"
|
|
#include "servconf.h"
|
|
#include "uidswap.h"
|
|
#include "compat.h"
|
|
#include <poll.h>
|
|
#include <time.h>
|
|
|
|
#ifdef LIBWRAP
|
|
#include <tcpd.h>
|
|
#include <syslog.h>
|
|
int allow_severity = LOG_INFO;
|
|
int deny_severity = LOG_WARNING;
|
|
#endif /* LIBWRAP */
|
|
|
|
#ifdef __FreeBSD__
|
|
#define LOGIN_CAP
|
|
#define _PATH_CHPASS "/usr/bin/passwd"
|
|
#endif /* __FreeBSD__ */
|
|
|
|
#ifdef LOGIN_CAP
|
|
#include <login_cap.h>
|
|
#endif /* LOGIN_CAP */
|
|
|
|
#ifndef O_NOCTTY
|
|
#define O_NOCTTY 0
|
|
#endif
|
|
|
|
#ifdef KRB5
|
|
#include <krb5.h>
|
|
krb5_context ssh_context = NULL;
|
|
krb5_principal tkt_client = NULL; /* Principal from the received ticket.
|
|
Also is used as an indication of succesful krb5 authentization. */
|
|
#endif /* KRB5 */
|
|
|
|
|
|
/* Local Xauthority file. */
|
|
static char *xauthfile = NULL;
|
|
|
|
/* Server configuration options. */
|
|
ServerOptions options;
|
|
|
|
/* Name of the server configuration file. */
|
|
char *config_file_name = SERVER_CONFIG_FILE;
|
|
|
|
/*
|
|
* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
|
|
* Default value is AF_UNSPEC means both IPv4 and IPv6.
|
|
*/
|
|
int IPv4or6 = AF_UNSPEC;
|
|
|
|
/*
|
|
* 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 is being started from inetd. */
|
|
int inetd_flag = 0;
|
|
|
|
/* debug goes to stderr unless inetd_flag is set */
|
|
int log_stderr = 0;
|
|
|
|
/* argv[0] without path. */
|
|
char *av0;
|
|
|
|
/* Saved arguments to main(). */
|
|
char **saved_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;
|
|
|
|
/* Flags set in auth-rsa from authorized_keys flags. These are set in auth-rsa.c. */
|
|
int no_port_forwarding_flag = 0;
|
|
int no_agent_forwarding_flag = 0;
|
|
int no_x11_forwarding_flag = 0;
|
|
int no_pty_flag = 0;
|
|
|
|
/* RSA authentication "command=" option. */
|
|
char *forced_command = NULL;
|
|
|
|
/* RSA authentication "environment=" options. */
|
|
struct envstring *custom_environment = NULL;
|
|
|
|
/* Session id for the current session. */
|
|
unsigned char session_id[16];
|
|
|
|
/*
|
|
* 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 {
|
|
RSA *private_key; /* Private part of server key. */
|
|
RSA *host_key; /* Private part of host key. */
|
|
} sensitive_data;
|
|
|
|
/*
|
|
* Flag indicating whether the current session key has been used. This flag
|
|
* is set whenever the key is used, and cleared when the key is regenerated.
|
|
*/
|
|
int key_used = 0;
|
|
|
|
/* This is set to true when SIGHUP is received. */
|
|
int received_sighup = 0;
|
|
|
|
/* Public side of the server key. This value is regenerated regularly with
|
|
the private key. */
|
|
RSA *public_key;
|
|
|
|
/* These are used to implement connections_per_period. */
|
|
struct magic_connection {
|
|
struct timeval connections_begin;
|
|
unsigned int connections_this_period;
|
|
} *magic_connections;
|
|
/* Magic number, too! TODO: this doesn't have to be static. */
|
|
const size_t MAGIC_CONNECTIONS_SIZE = 1;
|
|
|
|
static __inline int
|
|
magic_hash(struct sockaddr *sa) {
|
|
|
|
return 0;
|
|
}
|
|
|
|
static __inline struct timeval
|
|
timevaldiff(struct timeval *tv1, struct timeval *tv2) {
|
|
struct timeval diff;
|
|
int carry;
|
|
|
|
carry = tv1->tv_usec > tv2->tv_usec;
|
|
diff.tv_sec = tv2->tv_sec - tv1->tv_sec - (carry ? 0 : 1);
|
|
diff.tv_usec = tv2->tv_usec - tv1->tv_usec + (carry ? 1000000 : 0);
|
|
|
|
return diff;
|
|
}
|
|
|
|
/* Prototypes for various functions defined later in this file. */
|
|
void do_ssh_kex();
|
|
void do_authentication();
|
|
void do_authloop(struct passwd * pw);
|
|
void do_fake_authloop(char *user);
|
|
void do_authenticated(struct passwd * pw);
|
|
void do_exec_pty(const char *command, int ptyfd, int ttyfd,
|
|
const char *ttyname, struct passwd * pw, const char *term,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data);
|
|
void do_exec_no_pty(const char *command, struct passwd * pw,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data);
|
|
void do_child(const char *command, struct passwd * pw, const char *term,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data, const char *ttyname);
|
|
|
|
/*
|
|
* Remove local Xauthority file.
|
|
*/
|
|
void
|
|
xauthfile_cleanup_proc(void *ignore)
|
|
{
|
|
debug("xauthfile_cleanup_proc called");
|
|
|
|
if (xauthfile != NULL) {
|
|
char *p;
|
|
unlink(xauthfile);
|
|
p = strrchr(xauthfile, '/');
|
|
if (p != NULL) {
|
|
*p = '\0';
|
|
rmdir(xauthfile);
|
|
}
|
|
xfree(xauthfile);
|
|
xauthfile = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Close all listening sockets
|
|
*/
|
|
void
|
|
close_listen_socks(void)
|
|
{
|
|
int i;
|
|
for (i = 0; i < num_listen_socks; i++)
|
|
close(listen_socks[i]);
|
|
num_listen_socks = -1;
|
|
}
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
void
|
|
sighup_handler(int sig)
|
|
{
|
|
received_sighup = 1;
|
|
signal(SIGHUP, sighup_handler);
|
|
}
|
|
|
|
/*
|
|
* Called from the main program after receiving SIGHUP.
|
|
* Restarts the server.
|
|
*/
|
|
void
|
|
sighup_restart()
|
|
{
|
|
log("Received SIGHUP; restarting.");
|
|
close_listen_socks();
|
|
execv(saved_argv[0], saved_argv);
|
|
log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno));
|
|
exit(1);
|
|
}
|
|
|
|
/*
|
|
* Generic signal handler for terminating signals in the master daemon.
|
|
* These close the listen socket; not closing it seems to cause "Address
|
|
* already in use" problems on some machines, which is inconvenient.
|
|
*/
|
|
void
|
|
sigterm_handler(int sig)
|
|
{
|
|
log("Received signal %d; terminating.", sig);
|
|
close_listen_socks();
|
|
exit(255);
|
|
}
|
|
|
|
/*
|
|
* SIGCHLD handler. This is called whenever a child dies. This will then
|
|
* reap any zombies left by exited c.
|
|
*/
|
|
void
|
|
main_sigchld_handler(int sig)
|
|
{
|
|
int save_errno = errno;
|
|
int status;
|
|
|
|
while (waitpid(-1, &status, WNOHANG) > 0)
|
|
;
|
|
|
|
signal(SIGCHLD, main_sigchld_handler);
|
|
errno = save_errno;
|
|
}
|
|
|
|
/*
|
|
* Signal handler for the alarm after the login grace period has expired.
|
|
*/
|
|
void
|
|
grace_alarm_handler(int sig)
|
|
{
|
|
/* Close the connection. */
|
|
packet_close();
|
|
|
|
/* Log error and exit. */
|
|
fatal("Timeout before authentication for %s.", get_remote_ipaddr());
|
|
}
|
|
|
|
/*
|
|
* convert ssh auth msg type into description
|
|
*/
|
|
char *
|
|
get_authname(int type)
|
|
{
|
|
static char buf[1024];
|
|
switch (type) {
|
|
case SSH_CMSG_AUTH_PASSWORD:
|
|
return "password";
|
|
case SSH_CMSG_AUTH_RSA:
|
|
return "rsa";
|
|
case SSH_CMSG_AUTH_RHOSTS_RSA:
|
|
return "rhosts-rsa";
|
|
case SSH_CMSG_AUTH_RHOSTS:
|
|
return "rhosts";
|
|
#ifdef KRB4
|
|
case SSH_CMSG_AUTH_KRB4:
|
|
return "kerberosV4";
|
|
#endif
|
|
#ifdef KRB5
|
|
case SSH_CMSG_AUTH_KRB5:
|
|
return "kerberosV5";
|
|
#endif /* KRB5 */
|
|
#ifdef SKEY
|
|
case SSH_CMSG_AUTH_TIS_RESPONSE:
|
|
return "s/key";
|
|
#endif
|
|
}
|
|
snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
|
|
return buf;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
void
|
|
key_regeneration_alarm(int sig)
|
|
{
|
|
int save_errno = errno;
|
|
|
|
/* Check if we should generate a new key. */
|
|
if (key_used) {
|
|
/* This should really be done in the background. */
|
|
log("Generating new %d bit RSA key.", options.server_key_bits);
|
|
|
|
if (sensitive_data.private_key != NULL)
|
|
RSA_free(sensitive_data.private_key);
|
|
sensitive_data.private_key = RSA_new();
|
|
|
|
if (public_key != NULL)
|
|
RSA_free(public_key);
|
|
public_key = RSA_new();
|
|
|
|
rsa_generate_key(sensitive_data.private_key, public_key,
|
|
options.server_key_bits);
|
|
arc4random_stir();
|
|
key_used = 0;
|
|
log("RSA key generation complete.");
|
|
}
|
|
/* Reschedule the alarm. */
|
|
signal(SIGALRM, key_regeneration_alarm);
|
|
alarm(options.key_regeneration_time);
|
|
errno = save_errno;
|
|
}
|
|
|
|
/*
|
|
* 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, i, fdsetsz, pid, on = 1;
|
|
socklen_t fromlen;
|
|
int connections_per_period_exceeded = 0;
|
|
int remote_major, remote_minor;
|
|
int silentrsa = 0;
|
|
fd_set *fdset;
|
|
struct sockaddr_storage from;
|
|
char buf[100]; /* Must not be larger than remote_version. */
|
|
char remote_version[100]; /* Must be at least as big as buf. */
|
|
const char *remote_ip;
|
|
int remote_port;
|
|
char *comment;
|
|
FILE *f;
|
|
struct linger linger;
|
|
struct addrinfo *ai;
|
|
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
|
|
int listen_sock, maxfd;
|
|
|
|
/* Save argv[0]. */
|
|
saved_argv = av;
|
|
if (strchr(av[0], '/'))
|
|
av0 = strrchr(av[0], '/') + 1;
|
|
else
|
|
av0 = av[0];
|
|
|
|
/* 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:diqQ46")) != EOF) {
|
|
switch (opt) {
|
|
case '4':
|
|
IPv4or6 = AF_INET;
|
|
break;
|
|
case '6':
|
|
IPv4or6 = AF_INET6;
|
|
break;
|
|
case 'f':
|
|
config_file_name = optarg;
|
|
break;
|
|
case 'd':
|
|
debug_flag = 1;
|
|
options.log_level = SYSLOG_LEVEL_DEBUG;
|
|
break;
|
|
case 'i':
|
|
inetd_flag = 1;
|
|
break;
|
|
case 'Q':
|
|
silentrsa = 1;
|
|
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)
|
|
fatal("too many ports.\n");
|
|
options.ports[options.num_ports++] = 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':
|
|
client_version_string = optarg;
|
|
/* only makes sense with inetd_flag, i.e. no listen() */
|
|
inetd_flag = 1;
|
|
break;
|
|
case '?':
|
|
default:
|
|
fprintf(stderr, "sshd version %s\n", SSH_VERSION);
|
|
fprintf(stderr, "Usage: %s [options]\n", av0);
|
|
fprintf(stderr, "Options:\n");
|
|
fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE);
|
|
fprintf(stderr, " -d Debugging mode\n");
|
|
fprintf(stderr, " -i Started from inetd\n");
|
|
fprintf(stderr, " -q Quiet (no logging)\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, " -4 Use IPv4 only\n");
|
|
fprintf(stderr, " -6 Use IPv6 only\n");
|
|
exit(1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Force logging to stderr until we have loaded the private host
|
|
* key (unless started from inetd)
|
|
*/
|
|
log_init(av0,
|
|
options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
|
|
options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
|
|
!inetd_flag);
|
|
|
|
/* check if RSA support exists */
|
|
if (rsa_alive() == 0) {
|
|
if (silentrsa == 0)
|
|
printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n");
|
|
log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)");
|
|
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, "Bad server key size.\n");
|
|
exit(1);
|
|
}
|
|
/* 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);
|
|
|
|
sensitive_data.host_key = RSA_new();
|
|
errno = 0;
|
|
/* Load the host key. It must have empty passphrase. */
|
|
if (!load_private_key(options.host_key_file, "",
|
|
sensitive_data.host_key, &comment)) {
|
|
error("Could not load host key: %.200s: %.100s",
|
|
options.host_key_file, strerror(errno));
|
|
exit(1);
|
|
}
|
|
xfree(comment);
|
|
|
|
/* Initialize the log (it is reinitialized below in case we
|
|
forked). */
|
|
if (debug_flag && !inetd_flag)
|
|
log_stderr = 1;
|
|
log_init(av0, 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) {
|
|
#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("/dev/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(av0, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/* 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.host_key->n) - SSH_KEY_BITS_RESERVED &&
|
|
options.server_key_bits <
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
options.server_key_bits =
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED;
|
|
debug("Forcing server key to %d bits to make it differ from host key.",
|
|
options.server_key_bits);
|
|
}
|
|
/* Do not display messages to stdout in RSA code. */
|
|
rsa_set_verbose(0);
|
|
|
|
/* Initialize the random number generator. */
|
|
arc4random_stir();
|
|
|
|
/* Chdir to the root directory so that the current disk can be
|
|
unmounted if desired. */
|
|
chdir("/");
|
|
|
|
/* 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);
|
|
|
|
public_key = RSA_new();
|
|
sensitive_data.private_key = RSA_new();
|
|
|
|
log("Generating %d bit RSA key.", options.server_key_bits);
|
|
rsa_generate_key(sensitive_data.private_key, public_key,
|
|
options.server_key_bits);
|
|
arc4random_stir();
|
|
log("RSA key generation complete.");
|
|
} 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, 0);
|
|
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,
|
|
(void *) &on, sizeof(on));
|
|
linger.l_onoff = 1;
|
|
linger.l_linger = 5;
|
|
setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
|
|
(void *) &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) {
|
|
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 (!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(SSH_DAEMON_PID_FILE, "w");
|
|
if (f) {
|
|
fprintf(f, "%u\n", (unsigned int) getpid());
|
|
fclose(f);
|
|
}
|
|
}
|
|
|
|
public_key = RSA_new();
|
|
sensitive_data.private_key = RSA_new();
|
|
|
|
log("Generating %d bit RSA key.", options.server_key_bits);
|
|
rsa_generate_key(sensitive_data.private_key, public_key,
|
|
options.server_key_bits);
|
|
arc4random_stir();
|
|
log("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);
|
|
|
|
/* Arrange SIGCHLD to be caught. */
|
|
signal(SIGCHLD, main_sigchld_handler);
|
|
|
|
/* setup fd set for listen */
|
|
maxfd = 0;
|
|
for (i = 0; i < num_listen_socks; i++)
|
|
if (listen_socks[i] > maxfd)
|
|
maxfd = listen_socks[i];
|
|
fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
|
|
fdset = (fd_set *)xmalloc(fdsetsz);
|
|
|
|
/* Initialize the magic_connections table. It's magical! */
|
|
magic_connections = calloc(MAGIC_CONNECTIONS_SIZE,
|
|
sizeof(struct magic_connection));
|
|
if (magic_connections == NULL)
|
|
fatal("calloc: %s", strerror(errno));
|
|
|
|
/*
|
|
* 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. */
|
|
memset(fdset, 0, fdsetsz);
|
|
for (i = 0; i < num_listen_socks; i++)
|
|
FD_SET(listen_socks[i], fdset);
|
|
if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) {
|
|
if (errno != EINTR)
|
|
error("select: %.100s", strerror(errno));
|
|
continue;
|
|
}
|
|
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));
|
|
continue;
|
|
}
|
|
if (options.connections_per_period != 0) {
|
|
struct timeval diff, connections_end;
|
|
struct magic_connection *mc;
|
|
|
|
(void)gettimeofday(&connections_end, NULL);
|
|
mc = &magic_connections[magic_hash((struct sockaddr *)0)];
|
|
diff = timevaldiff(&mc->connections_begin, &connections_end);
|
|
if (diff.tv_sec >= options.connections_period) {
|
|
/*
|
|
* Slide the window forward only after completely
|
|
* leaving it.
|
|
*/
|
|
mc->connections_begin = connections_end;
|
|
mc->connections_this_period = 1;
|
|
} else {
|
|
if (++mc->connections_this_period >
|
|
options.connections_per_period)
|
|
connections_per_period_exceeded = 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Got connection. Fork a child to handle it unless
|
|
* we are in debugging mode or the maximum number of
|
|
* connections per period has been exceeded.
|
|
*/
|
|
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;
|
|
pid = getpid();
|
|
break;
|
|
} else if (connections_per_period_exceeded) {
|
|
log("Connection rate limit of %u/%us has been exceeded; "
|
|
"dropping connection from %s.",
|
|
options.connections_per_period, options.connections_period,
|
|
ntop);
|
|
connections_per_period_exceeded = 0;
|
|
} else {
|
|
/*
|
|
* 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_socks();
|
|
sock_in = newsock;
|
|
sock_out = newsock;
|
|
log_init(av0, 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 %d.", pid);
|
|
|
|
/* Mark that the key has been used (it was "given" to the child). */
|
|
key_used = 1;
|
|
|
|
arc4random_stir();
|
|
|
|
/* Close the new socket (the child is now taking care of it). */
|
|
close(newsock);
|
|
} /* for (i = 0; i < num_listen_socks; i++) */
|
|
/* child process check (or debug mode) */
|
|
if (num_listen_socks < 0)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* 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)); */
|
|
linger.l_onoff = 1;
|
|
linger.l_linger = 5;
|
|
setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
|
|
|
|
/*
|
|
* 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();
|
|
|
|
/* Check whether logins are denied from this host. */
|
|
#ifdef LIBWRAP
|
|
{
|
|
struct request_info req;
|
|
|
|
request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL);
|
|
fromhost(&req);
|
|
|
|
if (!hosts_access(&req)) {
|
|
close(sock_in);
|
|
close(sock_out);
|
|
refuse(&req);
|
|
}
|
|
verbose("Connection from %.500s port %d", eval_client(&req), remote_port);
|
|
}
|
|
#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);
|
|
|
|
if (client_version_string != NULL) {
|
|
/* we are exec'ed by sshd2, so skip exchange of protocol version */
|
|
strlcpy(buf, client_version_string, sizeof(buf));
|
|
} else {
|
|
/* Send our protocol version identification. */
|
|
snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
|
|
PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
|
|
if (atomicio(write, sock_out, buf, strlen(buf)) != strlen(buf)) {
|
|
log("Could not write ident string to %s.", remote_ip);
|
|
fatal_cleanup();
|
|
}
|
|
|
|
/* Read other side\'s version identification. */
|
|
for (i = 0; i < sizeof(buf) - 1; i++) {
|
|
if (read(sock_in, &buf[i], 1) != 1) {
|
|
log("Did not receive ident string from %s.", remote_ip);
|
|
fatal_cleanup();
|
|
}
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
char *s = "Protocol mismatch.\n";
|
|
|
|
(void) atomicio(write, sock_out, s, strlen(s));
|
|
close(sock_in);
|
|
close(sock_out);
|
|
log("Bad protocol version identification '%.100s' from %s",
|
|
buf, remote_ip);
|
|
fatal_cleanup();
|
|
}
|
|
debug("Client protocol version %d.%d; client software version %.100s",
|
|
remote_major, remote_minor, remote_version);
|
|
if (remote_major != PROTOCOL_MAJOR) {
|
|
char *s = "Protocol major versions differ.\n";
|
|
|
|
(void) atomicio(write, sock_out, s, strlen(s));
|
|
close(sock_in);
|
|
close(sock_out);
|
|
log("Protocol major versions differ for %s: %d vs. %d",
|
|
remote_ip, PROTOCOL_MAJOR, remote_major);
|
|
fatal_cleanup();
|
|
}
|
|
/* Check that the client has sufficiently high software version. */
|
|
if (remote_major == 1 && remote_minor < 3)
|
|
packet_disconnect("Your ssh version is too old and is no longer supported. Please install a newer version.");
|
|
|
|
if (remote_major == 1 && remote_minor == 3) {
|
|
/* note that this disables agent-forwarding */
|
|
enable_compat13();
|
|
}
|
|
/*
|
|
* Check that the connection comes from a privileged port. Rhosts-
|
|
* and Rhosts-RSA-Authentication only make sense from priviledged
|
|
* 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 (remote_port >= IPPORT_RESERVED ||
|
|
remote_port < IPPORT_RESERVED / 2) {
|
|
options.rhosts_authentication = 0;
|
|
options.rhosts_rsa_authentication = 0;
|
|
}
|
|
#ifdef KRB4
|
|
if (!packet_connection_is_ipv4() &&
|
|
options.krb4_authentication) {
|
|
debug("Kerberos Authentication disabled, only available for IPv4.");
|
|
options.krb4_authentication = 0;
|
|
}
|
|
#endif /* KRB4 */
|
|
|
|
packet_set_nonblocking();
|
|
|
|
/* perform the key exchange */
|
|
do_ssh_kex();
|
|
|
|
/* authenticate user and start session */
|
|
do_authentication();
|
|
|
|
#ifdef KRB4
|
|
/* Cleanup user's ticket cache file. */
|
|
if (options.krb4_ticket_cleanup)
|
|
(void) dest_tkt();
|
|
#endif /* KRB4 */
|
|
|
|
/* Cleanup user's local Xauthority file. */
|
|
if (xauthfile)
|
|
xauthfile_cleanup_proc(NULL);
|
|
|
|
/* The connection has been terminated. */
|
|
verbose("Closing connection to %.100s", remote_ip);
|
|
packet_close();
|
|
exit(0);
|
|
}
|
|
|
|
/*
|
|
* SSH1 key exchange
|
|
*/
|
|
void
|
|
do_ssh_kex()
|
|
{
|
|
int i, len;
|
|
int plen, slen;
|
|
BIGNUM *session_key_int;
|
|
unsigned char session_key[SSH_SESSION_KEY_LENGTH];
|
|
unsigned char cookie[8];
|
|
unsigned int cipher_type, auth_mask, protocol_flags;
|
|
u_int32_t rand = 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)
|
|
rand = arc4random();
|
|
cookie[i] = rand & 0xff;
|
|
rand >>= 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(public_key->n));
|
|
packet_put_bignum(public_key->e);
|
|
packet_put_bignum(public_key->n);
|
|
|
|
/* Store our public host RSA key. */
|
|
packet_put_int(BN_num_bits(sensitive_data.host_key->n));
|
|
packet_put_bignum(sensitive_data.host_key->e);
|
|
packet_put_bignum(sensitive_data.host_key->n);
|
|
|
|
/* Put protocol flags. */
|
|
packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
|
|
|
|
/* Declare which ciphers we support. */
|
|
packet_put_int(cipher_mask());
|
|
|
|
/* Declare supported authentication types. */
|
|
auth_mask = 0;
|
|
if (options.rhosts_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RHOSTS;
|
|
if (options.rhosts_rsa_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
|
|
if (options.rsa_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_RSA;
|
|
#ifdef KRB4
|
|
if (options.krb4_authentication)
|
|
auth_mask |= 1 << SSH_AUTH_KRB4;
|
|
#endif
|
|
#ifdef KRB5
|
|
if (options.krb5_authentication) {
|
|
auth_mask |= 1 << SSH_AUTH_KRB5;
|
|
/* compatibility with MetaCentre ssh */
|
|
auth_mask |= 1 << SSH_AUTH_KRB4;
|
|
}
|
|
if (options.krb5_tgt_passing)
|
|
auth_mask |= 1 << SSH_PASS_KRB5_TGT;
|
|
#endif /* KRB5 */
|
|
|
|
#ifdef AFS
|
|
if (options.krb4_tgt_passing)
|
|
auth_mask |= 1 << SSH_PASS_KRB4_TGT;
|
|
if (options.afs_token_passing)
|
|
auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
|
|
#endif
|
|
#ifdef SKEY
|
|
if (options.skey_authentication == 1)
|
|
auth_mask |= 1 << SSH_AUTH_TIS;
|
|
#endif
|
|
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 public key and %d bit host key.",
|
|
BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n));
|
|
|
|
/* Read clients reply (cipher type and session key). */
|
|
packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
|
|
|
|
/* Get cipher type and check whether we accept this. */
|
|
cipher_type = packet_get_char();
|
|
|
|
if (!(cipher_mask() & (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. */
|
|
session_key_int = BN_new();
|
|
packet_get_bignum(session_key_int, &slen);
|
|
|
|
protocol_flags = packet_get_int();
|
|
packet_set_protocol_flags(protocol_flags);
|
|
|
|
packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
|
|
|
|
/*
|
|
* Decrypt it using our private server key and private host key (key
|
|
* with larger modulus first).
|
|
*/
|
|
if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) {
|
|
/* Private key has bigger modulus. */
|
|
if (BN_num_bits(sensitive_data.private_key->n) <
|
|
BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
|
|
get_remote_ipaddr(),
|
|
BN_num_bits(sensitive_data.private_key->n),
|
|
BN_num_bits(sensitive_data.host_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.private_key);
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.host_key);
|
|
} else {
|
|
/* Host key has bigger modulus (or they are equal). */
|
|
if (BN_num_bits(sensitive_data.host_key->n) <
|
|
BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) {
|
|
fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d",
|
|
get_remote_ipaddr(),
|
|
BN_num_bits(sensitive_data.host_key->n),
|
|
BN_num_bits(sensitive_data.private_key->n),
|
|
SSH_KEY_BITS_RESERVED);
|
|
}
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.host_key);
|
|
rsa_private_decrypt(session_key_int, session_key_int,
|
|
sensitive_data.private_key);
|
|
}
|
|
|
|
compute_session_id(session_id, cookie,
|
|
sensitive_data.host_key->n,
|
|
sensitive_data.private_key->n);
|
|
|
|
/* Destroy the private and public keys. They will no longer be needed. */
|
|
RSA_free(public_key);
|
|
RSA_free(sensitive_data.private_key);
|
|
RSA_free(sensitive_data.host_key);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
BN_mask_bits(session_key_int, sizeof(session_key) * 8);
|
|
len = BN_num_bytes(session_key_int);
|
|
if (len < 0 || len > sizeof(session_key))
|
|
fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d",
|
|
get_remote_ipaddr(),
|
|
len, sizeof(session_key));
|
|
memset(session_key, 0, sizeof(session_key));
|
|
BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
|
|
|
|
/* Destroy the decrypted integer. It is no longer needed. */
|
|
BN_clear_free(session_key_int);
|
|
|
|
/* 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];
|
|
|
|
/* 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 acknowledgement packet. Note that this packet is sent encrypted. */
|
|
packet_start(SSH_SMSG_SUCCESS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
}
|
|
|
|
|
|
/*
|
|
* Check if the user is allowed to log in via ssh. If user is listed in
|
|
* DenyUsers or user's primary group is listed in DenyGroups, false will
|
|
* be returned. If AllowUsers isn't empty and user isn't listed there, or
|
|
* if AllowGroups isn't empty and user isn't listed there, false will be
|
|
* returned.
|
|
* If the user's shell is not executable, false will be returned.
|
|
* Otherwise true is returned.
|
|
*/
|
|
static int
|
|
allowed_user(struct passwd * pw)
|
|
{
|
|
struct stat st;
|
|
struct group *grp;
|
|
int i;
|
|
|
|
/* Shouldn't be called if pw is NULL, but better safe than sorry... */
|
|
if (!pw)
|
|
return 0;
|
|
|
|
/* deny if shell does not exists or is not executable */
|
|
if (stat(pw->pw_shell, &st) != 0)
|
|
return 0;
|
|
if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))
|
|
return 0;
|
|
|
|
/* Return false if user is listed in DenyUsers */
|
|
if (options.num_deny_users > 0) {
|
|
if (!pw->pw_name)
|
|
return 0;
|
|
for (i = 0; i < options.num_deny_users; i++)
|
|
if (match_pattern(pw->pw_name, options.deny_users[i]))
|
|
return 0;
|
|
}
|
|
/* Return false if AllowUsers isn't empty and user isn't listed there */
|
|
if (options.num_allow_users > 0) {
|
|
if (!pw->pw_name)
|
|
return 0;
|
|
for (i = 0; i < options.num_allow_users; i++)
|
|
if (match_pattern(pw->pw_name, options.allow_users[i]))
|
|
break;
|
|
/* i < options.num_allow_users iff we break for loop */
|
|
if (i >= options.num_allow_users)
|
|
return 0;
|
|
}
|
|
/* Get the primary group name if we need it. Return false if it fails */
|
|
if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
|
|
grp = getgrgid(pw->pw_gid);
|
|
if (!grp)
|
|
return 0;
|
|
|
|
/* Return false if user's group is listed in DenyGroups */
|
|
if (options.num_deny_groups > 0) {
|
|
if (!grp->gr_name)
|
|
return 0;
|
|
for (i = 0; i < options.num_deny_groups; i++)
|
|
if (match_pattern(grp->gr_name, options.deny_groups[i]))
|
|
return 0;
|
|
}
|
|
/*
|
|
* Return false if AllowGroups isn't empty and user's group
|
|
* isn't listed there
|
|
*/
|
|
if (options.num_allow_groups > 0) {
|
|
if (!grp->gr_name)
|
|
return 0;
|
|
for (i = 0; i < options.num_allow_groups; i++)
|
|
if (match_pattern(grp->gr_name, options.allow_groups[i]))
|
|
break;
|
|
/* i < options.num_allow_groups iff we break for
|
|
loop */
|
|
if (i >= options.num_allow_groups)
|
|
return 0;
|
|
}
|
|
}
|
|
#ifndef __FreeBSD__ /* FreeBSD handle it later */
|
|
/* Fail if the account's expiration time has passed. */
|
|
if (pw->pw_expire != 0) {
|
|
struct timeval tv;
|
|
|
|
(void)gettimeofday(&tv, NULL);
|
|
if (tv.tv_sec >= pw->pw_expire)
|
|
return 0;
|
|
}
|
|
#endif /* !__FreeBSD__ */
|
|
/* We found no reason not to let this user try to log on... */
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Performs authentication of an incoming connection. Session key has already
|
|
* been exchanged and encryption is enabled.
|
|
*/
|
|
void
|
|
do_authentication()
|
|
{
|
|
struct passwd *pw, pwcopy;
|
|
int plen;
|
|
unsigned int ulen;
|
|
char *user;
|
|
#ifdef LOGIN_CAP
|
|
login_cap_t *lc;
|
|
#endif /* LOGIN_CAP */
|
|
#if defined(LOGIN_CAP) || defined(LOGIN_ACCESS)
|
|
const char *from_host, *from_ip;
|
|
|
|
from_host = get_canonical_hostname();
|
|
from_ip = get_remote_ipaddr();
|
|
#endif /* LOGIN_CAP || LOGIN_ACCESS */
|
|
|
|
/* Get the name of the user that we wish to log in as. */
|
|
packet_read_expect(&plen, SSH_CMSG_USER);
|
|
|
|
/* Get the user name. */
|
|
user = packet_get_string(&ulen);
|
|
packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
|
|
|
|
setproctitle("%s", user);
|
|
|
|
#ifdef AFS
|
|
/* If machine has AFS, set process authentication group. */
|
|
if (k_hasafs()) {
|
|
k_setpag();
|
|
k_unlog();
|
|
}
|
|
#endif /* AFS */
|
|
|
|
/* Verify that the user is a valid user. */
|
|
pw = getpwnam(user);
|
|
if (!pw || !allowed_user(pw))
|
|
do_fake_authloop(user);
|
|
xfree(user);
|
|
|
|
/* Take a copy of the returned structure. */
|
|
memset(&pwcopy, 0, sizeof(pwcopy));
|
|
pwcopy.pw_name = xstrdup(pw->pw_name);
|
|
pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
|
|
pwcopy.pw_uid = pw->pw_uid;
|
|
pwcopy.pw_gid = pw->pw_gid;
|
|
pwcopy.pw_dir = xstrdup(pw->pw_dir);
|
|
pwcopy.pw_shell = xstrdup(pw->pw_shell);
|
|
pwcopy.pw_class = xstrdup(pw->pw_class);
|
|
pwcopy.pw_expire = pw->pw_expire;
|
|
pwcopy.pw_change = pw->pw_change;
|
|
pw = &pwcopy;
|
|
|
|
/*
|
|
* If we are not running as root, the user must have the same uid as
|
|
* the server.
|
|
*/
|
|
if (getuid() != 0 && pw->pw_uid != getuid())
|
|
packet_disconnect("Cannot change user when server not running as root.");
|
|
|
|
debug("Attempting authentication for %.100s.", pw->pw_name);
|
|
|
|
/* If the user has no password, accept authentication immediately. */
|
|
if (options.password_authentication &&
|
|
#ifdef KRB5
|
|
!options.krb5_authentication &&
|
|
#endif /* KRB5 */
|
|
#ifdef KRB4
|
|
(!options.krb4_authentication || options.krb4_or_local_passwd) &&
|
|
#endif /* KRB4 */
|
|
auth_password(pw, "")) {
|
|
/* Authentication with empty password succeeded. */
|
|
log("Login for user %s from %.100s, accepted without authentication.",
|
|
pw->pw_name, get_remote_ipaddr());
|
|
} else {
|
|
/* Loop until the user has been authenticated or the
|
|
connection is closed, do_authloop() returns only if
|
|
authentication is successfull */
|
|
do_authloop(pw);
|
|
}
|
|
|
|
/* Check if the user is logging in as root and root logins are disallowed. */
|
|
if (pw->pw_uid == 0 && !options.permit_root_login) {
|
|
if (forced_command)
|
|
log("Root login accepted for forced command.");
|
|
else
|
|
packet_disconnect("ROOT LOGIN REFUSED FROM %.200s",
|
|
get_canonical_hostname());
|
|
}
|
|
|
|
#ifdef LOGIN_CAP
|
|
lc = login_getpwclass(pw);
|
|
if (lc == NULL)
|
|
lc = login_getclassbyname(NULL, pw);
|
|
if (!auth_hostok(lc, from_host, from_ip)) {
|
|
log("Denied connection for %.200s from %.200s [%.200s].",
|
|
pw->pw_name, from_host, from_ip);
|
|
packet_disconnect("Sorry, you are not allowed to connect.");
|
|
}
|
|
if (!auth_timeok(lc, time(NULL))) {
|
|
log("LOGIN %.200s REFUSED (TIME) FROM %.200s",
|
|
pw->pw_name, from_host);
|
|
packet_disconnect("Logins not available right now.");
|
|
}
|
|
login_close(lc);
|
|
#endif /* LOGIN_CAP */
|
|
#ifdef LOGIN_ACCESS
|
|
if (!login_access(pw->pw_name, from_host)) {
|
|
log("Denied connection for %.200s from %.200s [%.200s].",
|
|
pw->pw_name, from_host, from_ip);
|
|
packet_disconnect("Sorry, you are not allowed to connect.");
|
|
}
|
|
#endif /* LOGIN_ACCESS */
|
|
|
|
if (pw->pw_uid == 0)
|
|
log("ROOT LOGIN as '%.100s' from %.100s",
|
|
pw->pw_name, get_canonical_hostname());
|
|
|
|
/* The user has been authenticated and accepted. */
|
|
packet_start(SSH_SMSG_SUCCESS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Perform session preparation. */
|
|
do_authenticated(pw);
|
|
}
|
|
|
|
#define AUTH_FAIL_MAX 6
|
|
#define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2)
|
|
#define AUTH_FAIL_MSG "Too many authentication failures for %.100s"
|
|
|
|
/*
|
|
* read packets and try to authenticate local user *pw.
|
|
* return if authentication is successfull
|
|
*/
|
|
void
|
|
do_authloop(struct passwd * pw)
|
|
{
|
|
int attempt = 0;
|
|
unsigned int bits;
|
|
RSA *client_host_key;
|
|
BIGNUM *n;
|
|
char *client_user, *password;
|
|
char user[1024];
|
|
unsigned int dlen;
|
|
int plen, nlen, elen;
|
|
unsigned int ulen;
|
|
int type = 0;
|
|
void (*authlog) (const char *fmt,...) = verbose;
|
|
#ifdef HAVE_LIBPAM
|
|
int pam_retval;
|
|
#endif /* HAVE_LIBPAM */
|
|
#if 0
|
|
#ifdef KRB5
|
|
{
|
|
krb5_error_code ret;
|
|
|
|
ret = krb5_init_context(&ssh_context);
|
|
if (ret)
|
|
verbose("Error while initializing Kerberos V5.");
|
|
krb5_init_ets(ssh_context);
|
|
|
|
}
|
|
#endif /* KRB5 */
|
|
#endif
|
|
|
|
/* Indicate that authentication is needed. */
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
for (attempt = 1;; attempt++) {
|
|
int authenticated = 0;
|
|
strlcpy(user, "", sizeof user);
|
|
|
|
/* Get a packet from the client. */
|
|
type = packet_read(&plen);
|
|
|
|
/* Process the packet. */
|
|
switch (type) {
|
|
#ifdef AFS
|
|
case SSH_CMSG_HAVE_KRB4_TGT:
|
|
if (!options.krb4_tgt_passing) {
|
|
/* packet_get_all(); */
|
|
verbose("Kerberos v4 tgt passing disabled.");
|
|
break;
|
|
} else {
|
|
/* Accept Kerberos v4 tgt. */
|
|
char *tgt = packet_get_string(&dlen);
|
|
packet_integrity_check(plen, 4 + dlen, type);
|
|
if (!auth_krb4_tgt(pw, tgt))
|
|
verbose("Kerberos v4 tgt REFUSED for %s", pw->pw_name);
|
|
xfree(tgt);
|
|
}
|
|
continue;
|
|
|
|
case SSH_CMSG_HAVE_AFS_TOKEN:
|
|
if (!options.afs_token_passing || !k_hasafs()) {
|
|
/* packet_get_all(); */
|
|
verbose("AFS token passing disabled.");
|
|
break;
|
|
} else {
|
|
/* Accept AFS token. */
|
|
char *token_string = packet_get_string(&dlen);
|
|
packet_integrity_check(plen, 4 + dlen, type);
|
|
if (!auth_afs_token(pw, token_string))
|
|
verbose("AFS token REFUSED for %s", pw->pw_name);
|
|
xfree(token_string);
|
|
}
|
|
continue;
|
|
#endif /* AFS */
|
|
#ifdef KRB4
|
|
case SSH_CMSG_AUTH_KRB4:
|
|
if (!options.krb4_authentication) {
|
|
/* packet_get_all(); */
|
|
verbose("Kerberos v4 authentication disabled.");
|
|
break;
|
|
} else {
|
|
/* Try Kerberos v4 authentication. */
|
|
KTEXT_ST auth;
|
|
char *tkt_user = NULL;
|
|
char *kdata = packet_get_string((unsigned int *) &auth.length);
|
|
packet_integrity_check(plen, 4 + auth.length, type);
|
|
|
|
if (auth.length < MAX_KTXT_LEN)
|
|
memcpy(auth.dat, kdata, auth.length);
|
|
xfree(kdata);
|
|
|
|
authenticated = auth_krb4(pw->pw_name, &auth, &tkt_user);
|
|
|
|
if (authenticated) {
|
|
snprintf(user, sizeof user, " tktuser %s", tkt_user);
|
|
xfree(tkt_user);
|
|
}
|
|
}
|
|
break;
|
|
#endif /* KRB4 */
|
|
#ifdef KRB5
|
|
case SSH_CMSG_AUTH_KRB5:
|
|
if (!options.krb5_authentication) {
|
|
verbose("Kerberos v5 authentication disabled.");
|
|
break;
|
|
} else {
|
|
krb5_data k5data;
|
|
#if 0
|
|
if (krb5_init_context(&ssh_context)) {
|
|
verbose("Error while initializing Kerberos V5.");
|
|
break;
|
|
}
|
|
krb5_init_ets(ssh_context);
|
|
#endif
|
|
|
|
k5data.data = packet_get_string(&k5data.length);
|
|
packet_integrity_check(plen, 4 + k5data.length, type);
|
|
if (auth_krb5(pw->pw_name, &k5data, &tkt_client)) {
|
|
/* pw->name is passed just for logging purposes
|
|
* */
|
|
/* authorize client against .k5login */
|
|
if (krb5_kuserok(ssh_context,
|
|
tkt_client,
|
|
pw->pw_name))
|
|
authenticated = 1;
|
|
}
|
|
xfree(k5data.data);
|
|
}
|
|
break;
|
|
#endif /* KRB5 */
|
|
|
|
case SSH_CMSG_AUTH_RHOSTS:
|
|
if (!options.rhosts_authentication) {
|
|
verbose("Rhosts authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Get client user name. Note that we just have to
|
|
* trust the client; this is one reason why rhosts
|
|
* authentication is insecure. (Another is
|
|
* IP-spoofing on a local network.)
|
|
*/
|
|
client_user = packet_get_string(&ulen);
|
|
packet_integrity_check(plen, 4 + ulen, type);
|
|
|
|
/* Try to authenticate using /etc/hosts.equiv and
|
|
.rhosts. */
|
|
authenticated = auth_rhosts(pw, client_user);
|
|
|
|
snprintf(user, sizeof user, " ruser %s", client_user);
|
|
xfree(client_user);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_RHOSTS_RSA:
|
|
if (!options.rhosts_rsa_authentication) {
|
|
verbose("Rhosts with RSA authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Get client user name. Note that we just have to
|
|
* trust the client; root on the client machine can
|
|
* claim to be any user.
|
|
*/
|
|
client_user = packet_get_string(&ulen);
|
|
|
|
/* Get the client host key. */
|
|
client_host_key = RSA_new();
|
|
if (client_host_key == NULL)
|
|
fatal("RSA_new failed");
|
|
client_host_key->e = BN_new();
|
|
client_host_key->n = BN_new();
|
|
if (client_host_key->e == NULL || client_host_key->n == NULL)
|
|
fatal("BN_new failed");
|
|
bits = packet_get_int();
|
|
packet_get_bignum(client_host_key->e, &elen);
|
|
packet_get_bignum(client_host_key->n, &nlen);
|
|
|
|
if (bits != BN_num_bits(client_host_key->n))
|
|
error("Warning: keysize mismatch for client_host_key: "
|
|
"actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
|
|
packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
|
|
|
|
authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
|
|
RSA_free(client_host_key);
|
|
|
|
snprintf(user, sizeof user, " ruser %s", client_user);
|
|
xfree(client_user);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_RSA:
|
|
if (!options.rsa_authentication) {
|
|
verbose("RSA authentication disabled.");
|
|
break;
|
|
}
|
|
/* RSA authentication requested. */
|
|
n = BN_new();
|
|
packet_get_bignum(n, &nlen);
|
|
packet_integrity_check(plen, nlen, type);
|
|
authenticated = auth_rsa(pw, n);
|
|
BN_clear_free(n);
|
|
break;
|
|
|
|
case SSH_CMSG_AUTH_PASSWORD:
|
|
if (!options.password_authentication) {
|
|
verbose("Password authentication disabled.");
|
|
break;
|
|
}
|
|
/*
|
|
* Read user password. It is in plain text, but was
|
|
* transmitted over the encrypted channel so it is
|
|
* not visible to an outside observer.
|
|
*/
|
|
password = packet_get_string(&dlen);
|
|
packet_integrity_check(plen, 4 + dlen, type);
|
|
|
|
/* Try authentication with the password. */
|
|
authenticated = auth_password(pw, password);
|
|
|
|
memset(password, 0, strlen(password));
|
|
xfree(password);
|
|
break;
|
|
|
|
#ifdef SKEY
|
|
case SSH_CMSG_AUTH_TIS:
|
|
debug("rcvd SSH_CMSG_AUTH_TIS");
|
|
if (options.skey_authentication == 1) {
|
|
char *skeyinfo = skey_keyinfo(pw->pw_name);
|
|
if (skeyinfo == NULL) {
|
|
debug("generating fake skeyinfo for %.100s.", pw->pw_name);
|
|
skeyinfo = skey_fake_keyinfo(pw->pw_name);
|
|
}
|
|
if (skeyinfo != NULL) {
|
|
/* we send our s/key- in tis-challenge messages */
|
|
debug("sending challenge '%s'", skeyinfo);
|
|
packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
|
|
packet_put_string(skeyinfo, strlen(skeyinfo));
|
|
packet_send();
|
|
packet_write_wait();
|
|
continue;
|
|
}
|
|
}
|
|
break;
|
|
case SSH_CMSG_AUTH_TIS_RESPONSE:
|
|
debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
|
|
if (options.skey_authentication == 1) {
|
|
char *response = packet_get_string(&dlen);
|
|
debug("skey response == '%s'", response);
|
|
packet_integrity_check(plen, 4 + dlen, type);
|
|
authenticated = (skey_haskey(pw->pw_name) == 0 &&
|
|
skey_passcheck(pw->pw_name, response) != -1);
|
|
xfree(response);
|
|
}
|
|
break;
|
|
#else
|
|
case SSH_CMSG_AUTH_TIS:
|
|
/* TIS Authentication is unsupported */
|
|
log("TIS authentication unsupported.");
|
|
break;
|
|
#endif
|
|
|
|
default:
|
|
/*
|
|
* Any unknown messages will be ignored (and failure
|
|
* returned) during authentication.
|
|
*/
|
|
log("Unknown message during authentication: type %d", type);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Check if the user is logging in as root and root logins
|
|
* are disallowed.
|
|
* Note that root login is allowed for forced commands.
|
|
*/
|
|
if (authenticated && pw->pw_uid == 0 && !options.permit_root_login) {
|
|
if (forced_command) {
|
|
log("Root login accepted for forced command.");
|
|
} else {
|
|
authenticated = 0;
|
|
log("ROOT LOGIN REFUSED FROM %.200s",
|
|
get_canonical_hostname());
|
|
}
|
|
}
|
|
|
|
/* Raise logging level */
|
|
if (authenticated ||
|
|
attempt == AUTH_FAIL_LOG ||
|
|
type == SSH_CMSG_AUTH_PASSWORD)
|
|
authlog = log;
|
|
|
|
authlog("%s %s for %.200s from %.200s port %d%s",
|
|
authenticated ? "Accepted" : "Failed",
|
|
get_authname(type),
|
|
pw->pw_uid == 0 ? "ROOT" : pw->pw_name,
|
|
get_remote_ipaddr(),
|
|
get_remote_port(),
|
|
user);
|
|
|
|
if (authenticated)
|
|
return;
|
|
|
|
if (attempt > AUTH_FAIL_MAX)
|
|
packet_disconnect(AUTH_FAIL_MSG, pw->pw_name);
|
|
|
|
/* Send a message indicating that the authentication attempt failed. */
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The user does not exist or access is denied,
|
|
* but fake indication that authentication is needed.
|
|
*/
|
|
void
|
|
do_fake_authloop(char *user)
|
|
{
|
|
int attempt = 0;
|
|
|
|
log("Faking authloop for illegal user %.200s from %.200s port %d",
|
|
user,
|
|
get_remote_ipaddr(),
|
|
get_remote_port());
|
|
|
|
/* Indicate that authentication is needed. */
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/*
|
|
* Keep reading packets, and always respond with a failure. This is
|
|
* to avoid disclosing whether such a user really exists.
|
|
*/
|
|
for (attempt = 1;; attempt++) {
|
|
/* Read a packet. This will not return if the client disconnects. */
|
|
int plen;
|
|
int type = packet_read(&plen);
|
|
#ifdef SKEY
|
|
unsigned int dlen;
|
|
char *password, *skeyinfo;
|
|
/* Try to send a fake s/key challenge. */
|
|
if (options.skey_authentication == 1 &&
|
|
(skeyinfo = skey_fake_keyinfo(user)) != NULL) {
|
|
password = NULL;
|
|
if (type == SSH_CMSG_AUTH_TIS) {
|
|
packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
|
|
packet_put_string(skeyinfo, strlen(skeyinfo));
|
|
packet_send();
|
|
packet_write_wait();
|
|
continue;
|
|
} else if (type == SSH_CMSG_AUTH_PASSWORD &&
|
|
options.password_authentication &&
|
|
(password = packet_get_string(&dlen)) != NULL &&
|
|
dlen == 5 &&
|
|
strncasecmp(password, "s/key", 5) == 0 ) {
|
|
packet_send_debug(skeyinfo);
|
|
}
|
|
if (password != NULL)
|
|
xfree(password);
|
|
}
|
|
#endif
|
|
if (attempt > AUTH_FAIL_MAX)
|
|
packet_disconnect(AUTH_FAIL_MSG, user);
|
|
|
|
/*
|
|
* Send failure. This should be indistinguishable from a
|
|
* failed authentication.
|
|
*/
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
}
|
|
/* NOTREACHED */
|
|
abort();
|
|
}
|
|
|
|
struct pty_cleanup_context {
|
|
const char *ttyname;
|
|
int pid;
|
|
};
|
|
|
|
/*
|
|
* Function to perform cleanup if we get aborted abnormally (e.g., due to a
|
|
* dropped connection).
|
|
*/
|
|
void
|
|
pty_cleanup_proc(void *context)
|
|
{
|
|
struct pty_cleanup_context *cu = context;
|
|
|
|
debug("pty_cleanup_proc called");
|
|
|
|
/* Record that the user has logged out. */
|
|
record_logout(cu->pid, cu->ttyname);
|
|
|
|
/* Release the pseudo-tty. */
|
|
pty_release(cu->ttyname);
|
|
}
|
|
|
|
/* simple cleanup: chown tty slave back to root */
|
|
static void
|
|
pty_release_proc(void *tty)
|
|
{
|
|
char *ttyname = tty;
|
|
pty_release(ttyname);
|
|
}
|
|
|
|
/*
|
|
* Prepares for an interactive session. This is called after the user has
|
|
* been successfully authenticated. During this message exchange, pseudo
|
|
* terminals are allocated, X11, TCP/IP, and authentication agent forwardings
|
|
* are requested, etc.
|
|
*/
|
|
void
|
|
do_authenticated(struct passwd * pw)
|
|
{
|
|
int type;
|
|
int compression_level = 0, enable_compression_after_reply = 0;
|
|
int have_pty = 0, ptyfd = -1, ttyfd = -1;
|
|
int row, col, xpixel, ypixel, screen;
|
|
char ttyname[64];
|
|
char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL;
|
|
int plen;
|
|
unsigned int dlen;
|
|
int n_bytes;
|
|
|
|
/*
|
|
* Cancel the alarm we set to limit the time taken for
|
|
* authentication.
|
|
*/
|
|
alarm(0);
|
|
|
|
/*
|
|
* Inform the channel mechanism that we are the server side and that
|
|
* the client may request to connect to any port at all. (The user
|
|
* could do it anyway, and we wouldn\'t know what is permitted except
|
|
* by the client telling us, so we can equally well trust the client
|
|
* not to request anything bogus.)
|
|
*/
|
|
if (!no_port_forwarding_flag)
|
|
channel_permit_all_opens();
|
|
|
|
/*
|
|
* We stay in this loop until the client requests to execute a shell
|
|
* or a command.
|
|
*/
|
|
while (1) {
|
|
|
|
/* Get a packet from the client. */
|
|
type = packet_read(&plen);
|
|
|
|
/* Process the packet. */
|
|
switch (type) {
|
|
case SSH_CMSG_REQUEST_COMPRESSION:
|
|
packet_integrity_check(plen, 4, type);
|
|
compression_level = packet_get_int();
|
|
if (compression_level < 1 || compression_level > 9) {
|
|
packet_send_debug("Received illegal compression level %d.",
|
|
compression_level);
|
|
goto fail;
|
|
}
|
|
/* Enable compression after we have responded with SUCCESS. */
|
|
enable_compression_after_reply = 1;
|
|
break;
|
|
|
|
case SSH_CMSG_REQUEST_PTY:
|
|
if (no_pty_flag) {
|
|
debug("Allocating a pty not permitted for this authentication.");
|
|
goto fail;
|
|
}
|
|
if (have_pty)
|
|
packet_disconnect("Protocol error: you already have a pty.");
|
|
|
|
debug("Allocating pty.");
|
|
|
|
/* Allocate a pty and open it. */
|
|
if (!pty_allocate(&ptyfd, &ttyfd, ttyname,
|
|
sizeof(ttyname))) {
|
|
error("Failed to allocate pty.");
|
|
goto fail;
|
|
}
|
|
fatal_add_cleanup(pty_release_proc, (void *)ttyname);
|
|
pty_setowner(pw, ttyname);
|
|
|
|
/* Get TERM from the packet. Note that the value may be of arbitrary length. */
|
|
term = packet_get_string(&dlen);
|
|
packet_integrity_check(dlen, strlen(term), type);
|
|
|
|
/* Remaining bytes */
|
|
n_bytes = plen - (4 + dlen + 4 * 4);
|
|
|
|
if (strcmp(term, "") == 0) {
|
|
xfree(term);
|
|
term = NULL;
|
|
}
|
|
|
|
/* Get window size from the packet. */
|
|
row = packet_get_int();
|
|
col = packet_get_int();
|
|
xpixel = packet_get_int();
|
|
ypixel = packet_get_int();
|
|
pty_change_window_size(ptyfd, row, col, xpixel, ypixel);
|
|
|
|
/* Get tty modes from the packet. */
|
|
tty_parse_modes(ttyfd, &n_bytes);
|
|
packet_integrity_check(plen, 4 + dlen + 4 * 4 + n_bytes, type);
|
|
|
|
/* Indicate that we now have a pty. */
|
|
have_pty = 1;
|
|
break;
|
|
|
|
case SSH_CMSG_X11_REQUEST_FORWARDING:
|
|
if (!options.x11_forwarding) {
|
|
packet_send_debug("X11 forwarding disabled in server configuration file.");
|
|
goto fail;
|
|
}
|
|
#ifdef XAUTH_PATH
|
|
if (no_x11_forwarding_flag) {
|
|
packet_send_debug("X11 forwarding not permitted for this authentication.");
|
|
goto fail;
|
|
}
|
|
debug("Received request for X11 forwarding with auth spoofing.");
|
|
if (display)
|
|
packet_disconnect("Protocol error: X11 display already set.");
|
|
{
|
|
unsigned int proto_len, data_len;
|
|
proto = packet_get_string(&proto_len);
|
|
data = packet_get_string(&data_len);
|
|
packet_integrity_check(plen, 4 + proto_len + 4 + data_len + 4, type);
|
|
}
|
|
if (packet_get_protocol_flags() & SSH_PROTOFLAG_SCREEN_NUMBER)
|
|
screen = packet_get_int();
|
|
else
|
|
screen = 0;
|
|
display = x11_create_display_inet(screen, options.x11_display_offset);
|
|
if (!display)
|
|
goto fail;
|
|
|
|
/* Setup to always have a local .Xauthority. */
|
|
xauthfile = xmalloc(MAXPATHLEN);
|
|
strlcpy(xauthfile, "/tmp/ssh-XXXXXXXX", MAXPATHLEN);
|
|
temporarily_use_uid(pw->pw_uid);
|
|
if (mkdtemp(xauthfile) == NULL) {
|
|
restore_uid();
|
|
error("private X11 dir: mkdtemp %s failed: %s",
|
|
xauthfile, strerror(errno));
|
|
xfree(xauthfile);
|
|
xauthfile = NULL;
|
|
goto fail;
|
|
}
|
|
strlcat(xauthfile, "/cookies", MAXPATHLEN);
|
|
open(xauthfile, O_RDWR|O_CREAT|O_EXCL, 0600);
|
|
restore_uid();
|
|
fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
|
|
break;
|
|
#else /* XAUTH_PATH */
|
|
packet_send_debug("No xauth program; cannot forward with spoofing.");
|
|
goto fail;
|
|
#endif /* XAUTH_PATH */
|
|
|
|
case SSH_CMSG_AGENT_REQUEST_FORWARDING:
|
|
if (no_agent_forwarding_flag || compat13) {
|
|
debug("Authentication agent forwarding not permitted for this authentication.");
|
|
goto fail;
|
|
}
|
|
debug("Received authentication agent forwarding request.");
|
|
auth_input_request_forwarding(pw);
|
|
break;
|
|
|
|
case SSH_CMSG_PORT_FORWARD_REQUEST:
|
|
if (no_port_forwarding_flag) {
|
|
debug("Port forwarding not permitted for this authentication.");
|
|
goto fail;
|
|
}
|
|
debug("Received TCP/IP port forwarding request.");
|
|
channel_input_port_forward_request(pw->pw_uid == 0);
|
|
break;
|
|
|
|
case SSH_CMSG_MAX_PACKET_SIZE:
|
|
if (packet_set_maxsize(packet_get_int()) < 0)
|
|
goto fail;
|
|
break;
|
|
|
|
case SSH_CMSG_EXEC_SHELL:
|
|
/* Set interactive/non-interactive mode. */
|
|
packet_set_interactive(have_pty || display != NULL,
|
|
options.keepalives);
|
|
|
|
if (forced_command != NULL)
|
|
goto do_forced_command;
|
|
debug("Forking shell.");
|
|
packet_integrity_check(plen, 0, type);
|
|
if (have_pty)
|
|
do_exec_pty(NULL, ptyfd, ttyfd, ttyname, pw, term, display, proto, data);
|
|
else
|
|
do_exec_no_pty(NULL, pw, display, proto, data);
|
|
return;
|
|
|
|
case SSH_CMSG_EXEC_CMD:
|
|
/* Set interactive/non-interactive mode. */
|
|
packet_set_interactive(have_pty || display != NULL,
|
|
options.keepalives);
|
|
|
|
if (forced_command != NULL)
|
|
goto do_forced_command;
|
|
/* Get command from the packet. */
|
|
{
|
|
unsigned int dlen;
|
|
command = packet_get_string(&dlen);
|
|
debug("Executing command '%.500s'", command);
|
|
packet_integrity_check(plen, 4 + dlen, type);
|
|
}
|
|
if (have_pty)
|
|
do_exec_pty(command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data);
|
|
else
|
|
do_exec_no_pty(command, pw, display, proto, data);
|
|
xfree(command);
|
|
return;
|
|
#ifdef KRB5
|
|
case SSH_CMSG_HAVE_KRB5_TGT:
|
|
/* Passing krb5 ticket */
|
|
if (!options.krb5_tgt_passing
|
|
/*|| !options.krb5_authentication */) {
|
|
|
|
}
|
|
|
|
if (tkt_client == NULL) {
|
|
/* passing tgt without krb5 authentication */
|
|
}
|
|
|
|
{
|
|
krb5_data tgt;
|
|
tgt.data = packet_get_string(&tgt.length);
|
|
|
|
if (!auth_krb5_tgt(pw->pw_name, &tgt, tkt_client)) {
|
|
verbose ("Kerberos V5 TGT refused for %.100s", pw->pw_name);
|
|
xfree(tgt.data);
|
|
goto fail;
|
|
}
|
|
xfree(tgt.data);
|
|
|
|
break;
|
|
}
|
|
#endif /* KRB5 */
|
|
|
|
default:
|
|
/*
|
|
* Any unknown messages in this phase are ignored,
|
|
* and a failure message is returned.
|
|
*/
|
|
log("Unknown packet type received after authentication: %d", type);
|
|
goto fail;
|
|
}
|
|
|
|
/* The request was successfully processed. */
|
|
packet_start(SSH_SMSG_SUCCESS);
|
|
packet_send();
|
|
packet_write_wait();
|
|
|
|
/* Enable compression now that we have replied if appropriate. */
|
|
if (enable_compression_after_reply) {
|
|
enable_compression_after_reply = 0;
|
|
packet_start_compression(compression_level);
|
|
}
|
|
continue;
|
|
|
|
fail:
|
|
/* The request failed. */
|
|
packet_start(SSH_SMSG_FAILURE);
|
|
packet_send();
|
|
packet_write_wait();
|
|
continue;
|
|
|
|
do_forced_command:
|
|
/*
|
|
* There is a forced command specified for this login.
|
|
* Execute it.
|
|
*/
|
|
debug("Executing forced command: %.900s", forced_command);
|
|
if (have_pty)
|
|
do_exec_pty(forced_command, ptyfd, ttyfd, ttyname, pw, term, display, proto, data);
|
|
else
|
|
do_exec_no_pty(forced_command, pw, display, proto, data);
|
|
return;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This is called to fork and execute a command when we have no tty. This
|
|
* will call do_child from the child, and server_loop from the parent after
|
|
* setting up file descriptors and such.
|
|
*/
|
|
void
|
|
do_exec_no_pty(const char *command, struct passwd * pw,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data)
|
|
{
|
|
int pid;
|
|
|
|
#ifdef USE_PIPES
|
|
int pin[2], pout[2], perr[2];
|
|
/* Allocate pipes for communicating with the program. */
|
|
if (pipe(pin) < 0 || pipe(pout) < 0 || pipe(perr) < 0)
|
|
packet_disconnect("Could not create pipes: %.100s",
|
|
strerror(errno));
|
|
#else /* USE_PIPES */
|
|
int inout[2], err[2];
|
|
/* Uses socket pairs to communicate with the program. */
|
|
if (socketpair(AF_UNIX, SOCK_STREAM, 0, inout) < 0 ||
|
|
socketpair(AF_UNIX, SOCK_STREAM, 0, err) < 0)
|
|
packet_disconnect("Could not create socket pairs: %.100s",
|
|
strerror(errno));
|
|
#endif /* USE_PIPES */
|
|
|
|
setproctitle("%s@notty", pw->pw_name);
|
|
|
|
/* Fork the child. */
|
|
if ((pid = fork()) == 0) {
|
|
/* Child. Reinitialize the log since the pid has changed. */
|
|
log_init(av0, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/*
|
|
* Create a new session and process group since the 4.4BSD
|
|
* setlogin() affects the entire process group.
|
|
*/
|
|
if (setsid() < 0)
|
|
error("setsid failed: %.100s", strerror(errno));
|
|
|
|
#ifdef USE_PIPES
|
|
/*
|
|
* Redirect stdin. We close the parent side of the socket
|
|
* pair, and make the child side the standard input.
|
|
*/
|
|
close(pin[1]);
|
|
if (dup2(pin[0], 0) < 0)
|
|
perror("dup2 stdin");
|
|
close(pin[0]);
|
|
|
|
/* Redirect stdout. */
|
|
close(pout[0]);
|
|
if (dup2(pout[1], 1) < 0)
|
|
perror("dup2 stdout");
|
|
close(pout[1]);
|
|
|
|
/* Redirect stderr. */
|
|
close(perr[0]);
|
|
if (dup2(perr[1], 2) < 0)
|
|
perror("dup2 stderr");
|
|
close(perr[1]);
|
|
#else /* USE_PIPES */
|
|
/*
|
|
* Redirect stdin, stdout, and stderr. Stdin and stdout will
|
|
* use the same socket, as some programs (particularly rdist)
|
|
* seem to depend on it.
|
|
*/
|
|
close(inout[1]);
|
|
close(err[1]);
|
|
if (dup2(inout[0], 0) < 0) /* stdin */
|
|
perror("dup2 stdin");
|
|
if (dup2(inout[0], 1) < 0) /* stdout. Note: same socket as stdin. */
|
|
perror("dup2 stdout");
|
|
if (dup2(err[0], 2) < 0) /* stderr */
|
|
perror("dup2 stderr");
|
|
#endif /* USE_PIPES */
|
|
|
|
/* Do processing for the child (exec command etc). */
|
|
do_child(command, pw, NULL, display, auth_proto, auth_data, NULL);
|
|
/* NOTREACHED */
|
|
}
|
|
if (pid < 0)
|
|
packet_disconnect("fork failed: %.100s", strerror(errno));
|
|
#ifdef USE_PIPES
|
|
/* We are the parent. Close the child sides of the pipes. */
|
|
close(pin[0]);
|
|
close(pout[1]);
|
|
close(perr[1]);
|
|
|
|
/* Enter the interactive session. */
|
|
server_loop(pid, pin[1], pout[0], perr[0]);
|
|
/* server_loop has closed pin[1], pout[1], and perr[1]. */
|
|
#else /* USE_PIPES */
|
|
/* We are the parent. Close the child sides of the socket pairs. */
|
|
close(inout[0]);
|
|
close(err[0]);
|
|
|
|
/*
|
|
* Enter the interactive session. Note: server_loop must be able to
|
|
* handle the case that fdin and fdout are the same.
|
|
*/
|
|
server_loop(pid, inout[1], inout[1], err[1]);
|
|
/* server_loop has closed inout[1] and err[1]. */
|
|
#endif /* USE_PIPES */
|
|
}
|
|
|
|
/*
|
|
* This is called to fork and execute a command when we have a tty. This
|
|
* will call do_child from the child, and server_loop from the parent after
|
|
* setting up file descriptors, controlling tty, updating wtmp, utmp,
|
|
* lastlog, and other such operations.
|
|
*/
|
|
void
|
|
do_exec_pty(const char *command, int ptyfd, int ttyfd,
|
|
const char *ttyname, struct passwd * pw, const char *term,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data)
|
|
{
|
|
int pid, fdout;
|
|
int ptymaster;
|
|
const char *hostname;
|
|
time_t last_login_time;
|
|
char buf[100], *time_string;
|
|
FILE *f;
|
|
char line[256];
|
|
struct stat st;
|
|
int quiet_login;
|
|
struct sockaddr_storage from;
|
|
socklen_t fromlen;
|
|
struct pty_cleanup_context cleanup_context;
|
|
#ifdef LOGIN_CAP
|
|
login_cap_t *lc;
|
|
char *fname;
|
|
#endif /* LOGIN_CAP */
|
|
#ifdef __FreeBSD__
|
|
#define DEFAULT_WARN (2L * 7L * 86400L) /* Two weeks */
|
|
struct timeval tv;
|
|
time_t warntime = DEFAULT_WARN;
|
|
#endif /* __FreeBSD__ */
|
|
|
|
/* Get remote host name. */
|
|
hostname = get_canonical_hostname();
|
|
|
|
/*
|
|
* Get the time when the user last logged in. Buf will be set to
|
|
* contain the hostname the last login was from.
|
|
*/
|
|
if (!options.use_login) {
|
|
last_login_time = get_last_login_time(pw->pw_uid, pw->pw_name,
|
|
buf, sizeof(buf));
|
|
}
|
|
setproctitle("%s@%s", pw->pw_name, strrchr(ttyname, '/') + 1);
|
|
|
|
/* Fork the child. */
|
|
if ((pid = fork()) == 0) {
|
|
pid = getpid();
|
|
|
|
/* Child. Reinitialize the log because the pid has
|
|
changed. */
|
|
log_init(av0, options.log_level, options.log_facility, log_stderr);
|
|
|
|
/* Close the master side of the pseudo tty. */
|
|
close(ptyfd);
|
|
|
|
/* Make the pseudo tty our controlling tty. */
|
|
pty_make_controlling_tty(&ttyfd, ttyname);
|
|
|
|
/* Redirect stdin from the pseudo tty. */
|
|
if (dup2(ttyfd, fileno(stdin)) < 0)
|
|
error("dup2 stdin failed: %.100s", strerror(errno));
|
|
|
|
/* Redirect stdout to the pseudo tty. */
|
|
if (dup2(ttyfd, fileno(stdout)) < 0)
|
|
error("dup2 stdin failed: %.100s", strerror(errno));
|
|
|
|
/* Redirect stderr to the pseudo tty. */
|
|
if (dup2(ttyfd, fileno(stderr)) < 0)
|
|
error("dup2 stdin failed: %.100s", strerror(errno));
|
|
|
|
/* Close the extra descriptor for the pseudo tty. */
|
|
close(ttyfd);
|
|
|
|
/*
|
|
* Get IP address of client. This is needed because we want
|
|
* to record where the user logged in from. If the
|
|
* connection is not a socket, let the ip address be 0.0.0.0.
|
|
*/
|
|
memset(&from, 0, sizeof(from));
|
|
if (packet_get_connection_in() == packet_get_connection_out()) {
|
|
fromlen = sizeof(from);
|
|
if (getpeername(packet_get_connection_in(),
|
|
(struct sockaddr *) & from, &fromlen) < 0) {
|
|
debug("getpeername: %.100s", strerror(errno));
|
|
fatal_cleanup();
|
|
}
|
|
}
|
|
/* Record that there was a login on that terminal. */
|
|
record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname,
|
|
(struct sockaddr *)&from);
|
|
|
|
/* Check if .hushlogin exists. */
|
|
snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir);
|
|
quiet_login = stat(line, &st) >= 0;
|
|
#ifdef LOGIN_CAP
|
|
lc = login_getpwclass(pw);
|
|
if (lc == NULL)
|
|
lc = login_getclassbyname(NULL, pw);
|
|
quiet_login = login_getcapbool(lc, "hushlogin", quiet_login);
|
|
#endif /* LOGIN_CAP */
|
|
|
|
#ifdef __FreeBSD__
|
|
if (pw->pw_change || pw->pw_expire)
|
|
(void)gettimeofday(&tv, NULL);
|
|
#ifdef LOGIN_CAP
|
|
warntime = login_getcaptime(lc, "warnpassword",
|
|
DEFAULT_WARN, DEFAULT_WARN);
|
|
#endif /* LOGIN_CAP */
|
|
/*
|
|
* If the password change time is set and has passed, give the
|
|
* user a password expiry notice and chance to change it.
|
|
*/
|
|
if (pw->pw_change != 0) {
|
|
if (tv.tv_sec >= pw->pw_change) {
|
|
(void)printf(
|
|
"Sorry -- your password has expired.\n");
|
|
log("%s Password expired - forcing change",
|
|
pw->pw_name);
|
|
command = _PATH_CHPASS;
|
|
} else if (pw->pw_change - tv.tv_sec < warntime &&
|
|
!quiet_login)
|
|
(void)printf(
|
|
"Warning: your password expires on %s",
|
|
ctime(&pw->pw_change));
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
warntime = login_getcaptime(lc, "warnexpire",
|
|
DEFAULT_WARN, DEFAULT_WARN);
|
|
#endif /* LOGIN_CAP */
|
|
if (pw->pw_expire) {
|
|
if (tv.tv_sec >= pw->pw_expire) {
|
|
(void)printf(
|
|
"Sorry -- your account has expired.\n");
|
|
log(
|
|
"LOGIN %.200s REFUSED (EXPIRED) FROM %.200s ON TTY %.200s",
|
|
pw->pw_name, hostname, ttyname);
|
|
exit(254);
|
|
} else if (pw->pw_expire - tv.tv_sec < warntime &&
|
|
!quiet_login)
|
|
(void)printf(
|
|
"Warning: your account expires on %s",
|
|
ctime(&pw->pw_expire));
|
|
}
|
|
#endif /* __FreeBSD__ */
|
|
#ifdef LOGIN_CAP
|
|
if (!auth_ttyok(lc, ttyname)) {
|
|
(void)printf("Permission denied.\n");
|
|
log(
|
|
"LOGIN %.200s REFUSED (TTY) FROM %.200s ON TTY %.200s",
|
|
pw->pw_name, hostname, ttyname);
|
|
exit(254);
|
|
}
|
|
#endif /* LOGIN_CAP */
|
|
|
|
/*
|
|
* If the user has logged in before, display the time of last
|
|
* login. However, don't display anything extra if a command
|
|
* has been specified (so that ssh can be used to execute
|
|
* commands on a remote machine without users knowing they
|
|
* are going to another machine). Login(1) will do this for
|
|
* us as well, so check if login(1) is used
|
|
*/
|
|
if (command == NULL && last_login_time != 0 && !quiet_login &&
|
|
!options.use_login) {
|
|
/* Convert the date to a string. */
|
|
time_string = ctime(&last_login_time);
|
|
/* Remove the trailing newline. */
|
|
if (strchr(time_string, '\n'))
|
|
*strchr(time_string, '\n') = 0;
|
|
/* Display the last login time. Host if displayed
|
|
if known. */
|
|
if (strcmp(buf, "") == 0)
|
|
printf("Last login: %s\r\n", time_string);
|
|
else
|
|
printf("Last login: %s from %s\r\n", time_string, buf);
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
if (command == NULL && !quiet_login && !options.use_login) {
|
|
fname = login_getcapstr(lc, "copyright", NULL, NULL);
|
|
if (fname != NULL && (f = fopen(fname, "r")) != NULL) {
|
|
while (fgets(line, sizeof(line), f) != NULL)
|
|
fputs(line, stdout);
|
|
fclose(f);
|
|
} else
|
|
(void)printf("%s\n\t%s %s\n",
|
|
"Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994",
|
|
"The Regents of the University of California. ",
|
|
"All rights reserved.");
|
|
}
|
|
#endif /* LOGIN_CAP */
|
|
/*
|
|
* Print /etc/motd unless a command was specified or printing
|
|
* it was disabled in server options or login(1) will be
|
|
* used. Note that some machines appear to print it in
|
|
* /etc/profile or similar.
|
|
*/
|
|
if (command == NULL && options.print_motd && !quiet_login &&
|
|
!options.use_login) {
|
|
#ifdef LOGIN_CAP
|
|
fname = login_getcapstr(lc, "welcome", NULL, NULL);
|
|
if (fname == NULL || (f = fopen(fname, "r")) == NULL)
|
|
f = fopen("/etc/motd", "r");
|
|
#else /* !LOGIN_CAP */
|
|
f = fopen("/etc/motd", "r");
|
|
#endif /* LOGIN_CAP */
|
|
/* Print /etc/motd if it exists. */
|
|
if (f) {
|
|
while (fgets(line, sizeof(line), f))
|
|
fputs(line, stdout);
|
|
fclose(f);
|
|
}
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
login_close(lc);
|
|
#endif /* LOGIN_CAP */
|
|
|
|
/* Do common processing for the child, such as execing the command. */
|
|
do_child(command, pw, term, display, auth_proto, auth_data, ttyname);
|
|
/* NOTREACHED */
|
|
}
|
|
if (pid < 0)
|
|
packet_disconnect("fork failed: %.100s", strerror(errno));
|
|
/* Parent. Close the slave side of the pseudo tty. */
|
|
close(ttyfd);
|
|
|
|
/*
|
|
* Add a cleanup function to clear the utmp entry and record logout
|
|
* time in case we call fatal() (e.g., the connection gets closed).
|
|
*/
|
|
cleanup_context.pid = pid;
|
|
cleanup_context.ttyname = ttyname;
|
|
fatal_add_cleanup(pty_cleanup_proc, (void *) &cleanup_context);
|
|
fatal_remove_cleanup(pty_release_proc, (void *) ttyname);
|
|
|
|
/*
|
|
* Create another descriptor of the pty master side for use as the
|
|
* standard input. We could use the original descriptor, but this
|
|
* simplifies code in server_loop. The descriptor is bidirectional.
|
|
*/
|
|
fdout = dup(ptyfd);
|
|
if (fdout < 0)
|
|
packet_disconnect("dup #1 failed: %.100s", strerror(errno));
|
|
|
|
/* we keep a reference to the pty master */
|
|
ptymaster = dup(ptyfd);
|
|
if (ptymaster < 0)
|
|
packet_disconnect("dup #2 failed: %.100s", strerror(errno));
|
|
|
|
/* Enter interactive session. */
|
|
server_loop(pid, ptyfd, fdout, -1);
|
|
/* server_loop _has_ closed ptyfd and fdout. */
|
|
|
|
/* Cancel the cleanup function. */
|
|
fatal_remove_cleanup(pty_cleanup_proc, (void *) &cleanup_context);
|
|
|
|
/* Record that the user has logged out. */
|
|
record_logout(pid, ttyname);
|
|
|
|
/* Release the pseudo-tty. */
|
|
pty_release(ttyname);
|
|
|
|
/*
|
|
* Close the server side of the socket pairs. We must do this after
|
|
* the pty cleanup, so that another process doesn't get this pty
|
|
* while we're still cleaning up.
|
|
*/
|
|
if (close(ptymaster) < 0)
|
|
error("close(ptymaster): %s", strerror(errno));
|
|
}
|
|
|
|
/*
|
|
* Sets the value of the given variable in the environment. If the variable
|
|
* already exists, its value is overriden.
|
|
*/
|
|
void
|
|
child_set_env(char ***envp, unsigned int *envsizep, const char *name,
|
|
const char *value)
|
|
{
|
|
unsigned int i, namelen;
|
|
char **env;
|
|
|
|
/*
|
|
* Find the slot where the value should be stored. If the variable
|
|
* already exists, we reuse the slot; otherwise we append a new slot
|
|
* at the end of the array, expanding if necessary.
|
|
*/
|
|
env = *envp;
|
|
namelen = strlen(name);
|
|
for (i = 0; env[i]; i++)
|
|
if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
|
|
break;
|
|
if (env[i]) {
|
|
/* Reuse the slot. */
|
|
xfree(env[i]);
|
|
} else {
|
|
/* New variable. Expand if necessary. */
|
|
if (i >= (*envsizep) - 1) {
|
|
(*envsizep) += 50;
|
|
env = (*envp) = xrealloc(env, (*envsizep) * sizeof(char *));
|
|
}
|
|
/* Need to set the NULL pointer at end of array beyond the new slot. */
|
|
env[i + 1] = NULL;
|
|
}
|
|
|
|
/* Allocate space and format the variable in the appropriate slot. */
|
|
env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
|
|
snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
|
|
}
|
|
|
|
/*
|
|
* Reads environment variables from the given file and adds/overrides them
|
|
* into the environment. If the file does not exist, this does nothing.
|
|
* Otherwise, it must consist of empty lines, comments (line starts with '#')
|
|
* and assignments of the form name=value. No other forms are allowed.
|
|
*/
|
|
void
|
|
read_environment_file(char ***env, unsigned int *envsize,
|
|
const char *filename)
|
|
{
|
|
FILE *f;
|
|
char buf[4096];
|
|
char *cp, *value;
|
|
|
|
f = fopen(filename, "r");
|
|
if (!f)
|
|
return;
|
|
|
|
while (fgets(buf, sizeof(buf), f)) {
|
|
for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
|
|
;
|
|
if (!*cp || *cp == '#' || *cp == '\n')
|
|
continue;
|
|
if (strchr(cp, '\n'))
|
|
*strchr(cp, '\n') = '\0';
|
|
value = strchr(cp, '=');
|
|
if (value == NULL) {
|
|
fprintf(stderr, "Bad line in %.100s: %.200s\n", filename, buf);
|
|
continue;
|
|
}
|
|
/* Replace the equals sign by nul, and advance value to the value string. */
|
|
*value = '\0';
|
|
value++;
|
|
child_set_env(env, envsize, cp, value);
|
|
}
|
|
fclose(f);
|
|
}
|
|
|
|
/*
|
|
* Performs common processing for the child, such as setting up the
|
|
* environment, closing extra file descriptors, setting the user and group
|
|
* ids, and executing the command or shell.
|
|
*/
|
|
void
|
|
do_child(const char *command, struct passwd * pw, const char *term,
|
|
const char *display, const char *auth_proto,
|
|
const char *auth_data, const char *ttyname)
|
|
{
|
|
char *shell;
|
|
const char *cp = NULL;
|
|
char buf[256];
|
|
FILE *f;
|
|
unsigned int envsize, i;
|
|
char **env = NULL;
|
|
extern char **environ;
|
|
struct stat st;
|
|
char *argv[10];
|
|
#ifdef LOGIN_CAP
|
|
login_cap_t *lc;
|
|
|
|
lc = login_getpwclass(pw);
|
|
if (lc == NULL)
|
|
lc = login_getclassbyname(NULL, pw);
|
|
if (pw->pw_uid != 0)
|
|
auth_checknologin(lc);
|
|
#else /* !LOGIN_CAP */
|
|
f = fopen("/etc/nologin", "r");
|
|
if (f) {
|
|
/* /etc/nologin exists. Print its contents and exit. */
|
|
while (fgets(buf, sizeof(buf), f))
|
|
fputs(buf, stderr);
|
|
fclose(f);
|
|
if (pw->pw_uid != 0)
|
|
exit(254);
|
|
|
|
}
|
|
#endif /* LOGIN_CAP */
|
|
|
|
#ifdef LOGIN_CAP
|
|
if (options.use_login)
|
|
#endif /* LOGIN_CAP */
|
|
/* Set login name in the kernel. */
|
|
if (setlogin(pw->pw_name) < 0)
|
|
error("setlogin failed: %s", strerror(errno));
|
|
|
|
/* Set uid, gid, and groups. */
|
|
/* Login(1) does this as well, and it needs uid 0 for the "-h"
|
|
switch, so we let login(1) to this for us. */
|
|
if (!options.use_login) {
|
|
#ifdef LOGIN_CAP
|
|
char **tmpenv;
|
|
|
|
/* Initialize temp environment */
|
|
envsize = 64;
|
|
env = xmalloc(envsize * sizeof(char *));
|
|
env[0] = NULL;
|
|
|
|
child_set_env(&env, &envsize, "PATH",
|
|
(pw->pw_uid == 0) ?
|
|
_PATH_STDPATH : _PATH_DEFPATH);
|
|
|
|
snprintf(buf, sizeof buf, "%.200s/%.50s",
|
|
_PATH_MAILDIR, pw->pw_name);
|
|
child_set_env(&env, &envsize, "MAIL", buf);
|
|
|
|
if (getenv("TZ"))
|
|
child_set_env(&env, &envsize, "TZ", getenv("TZ"));
|
|
|
|
/* Save parent environment */
|
|
tmpenv = environ;
|
|
environ = env;
|
|
|
|
if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETALL) < 0)
|
|
fatal("setusercontext failed: %s", strerror(errno));
|
|
|
|
/* Restore parent environment */
|
|
env = environ;
|
|
environ = tmpenv;
|
|
|
|
for (envsize = 0; env[envsize] != NULL; ++envsize)
|
|
;
|
|
envsize = (envsize < 100) ? 100 : envsize + 16;
|
|
env = xrealloc(env, envsize * sizeof(char *));
|
|
|
|
#else /* !LOGIN_CAP */
|
|
|
|
if (getuid() == 0 || geteuid() == 0) {
|
|
if (setgid(pw->pw_gid) < 0) {
|
|
perror("setgid");
|
|
exit(1);
|
|
}
|
|
/* Initialize the group list. */
|
|
if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
|
|
perror("initgroups");
|
|
exit(1);
|
|
}
|
|
endgrent();
|
|
|
|
/* Permanently switch to the desired uid. */
|
|
permanently_set_uid(pw->pw_uid);
|
|
}
|
|
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
|
|
fatal("Failed to set uids to %d.", (int) pw->pw_uid);
|
|
#endif /* LOGIN_CAP */
|
|
}
|
|
/*
|
|
* Get the shell from the password data. An empty shell field is
|
|
* legal, and means /bin/sh.
|
|
*/
|
|
shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
|
|
#ifdef LOGIN_CAP
|
|
shell = login_getcapstr(lc, "shell", shell, shell);
|
|
#endif /* LOGIN_CAP */
|
|
|
|
#ifdef AFS
|
|
/* Try to get AFS tokens for the local cell. */
|
|
if (k_hasafs()) {
|
|
char cell[64];
|
|
|
|
if (k_afs_cell_of_file(pw->pw_dir, cell, sizeof(cell)) == 0)
|
|
krb_afslog(cell, 0);
|
|
|
|
krb_afslog(0, 0);
|
|
}
|
|
#endif /* AFS */
|
|
|
|
/* Initialize the environment. */
|
|
if (env == NULL) {
|
|
envsize = 100;
|
|
env = xmalloc(envsize * sizeof(char *));
|
|
env[0] = NULL;
|
|
}
|
|
|
|
if (!options.use_login) {
|
|
/* Set basic environment. */
|
|
child_set_env(&env, &envsize, "USER", pw->pw_name);
|
|
child_set_env(&env, &envsize, "LOGNAME", pw->pw_name);
|
|
child_set_env(&env, &envsize, "HOME", pw->pw_dir);
|
|
#ifndef LOGIN_CAP
|
|
child_set_env(&env, &envsize, "PATH", _PATH_STDPATH);
|
|
|
|
snprintf(buf, sizeof buf, "%.200s/%.50s",
|
|
_PATH_MAILDIR, pw->pw_name);
|
|
child_set_env(&env, &envsize, "MAIL", buf);
|
|
#endif /* !LOGIN_CAP */
|
|
|
|
/* Normal systems set SHELL by default. */
|
|
child_set_env(&env, &envsize, "SHELL", shell);
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
if (options.use_login)
|
|
#endif /* LOGIN_CAP */
|
|
if (getenv("TZ"))
|
|
child_set_env(&env, &envsize, "TZ", getenv("TZ"));
|
|
|
|
/* Set custom environment options from RSA authentication. */
|
|
while (custom_environment) {
|
|
struct envstring *ce = custom_environment;
|
|
char *s = ce->s;
|
|
int i;
|
|
for (i = 0; s[i] != '=' && s[i]; i++);
|
|
if (s[i] == '=') {
|
|
s[i] = 0;
|
|
child_set_env(&env, &envsize, s, s + i + 1);
|
|
}
|
|
custom_environment = ce->next;
|
|
xfree(ce->s);
|
|
xfree(ce);
|
|
}
|
|
|
|
snprintf(buf, sizeof buf, "%.50s %d %d",
|
|
get_remote_ipaddr(), get_remote_port(), get_local_port());
|
|
child_set_env(&env, &envsize, "SSH_CLIENT", buf);
|
|
|
|
if (ttyname)
|
|
child_set_env(&env, &envsize, "SSH_TTY", ttyname);
|
|
if (term)
|
|
child_set_env(&env, &envsize, "TERM", term);
|
|
if (display)
|
|
child_set_env(&env, &envsize, "DISPLAY", display);
|
|
|
|
#ifdef KRB4
|
|
{
|
|
extern char *ticket;
|
|
|
|
if (ticket)
|
|
child_set_env(&env, &envsize, "KRBTKFILE", ticket);
|
|
}
|
|
#endif /* KRB4 */
|
|
|
|
#ifdef KRB5
|
|
{
|
|
extern krb5_ccache mem_ccache;
|
|
|
|
if (mem_ccache) {
|
|
krb5_error_code problem;
|
|
krb5_ccache ccache;
|
|
#ifdef AFS
|
|
if (k_hasafs())
|
|
krb5_afslog(ssh_context, mem_ccache, NULL, NULL);
|
|
#endif /* AFS */
|
|
|
|
problem = krb5_cc_default(ssh_context, &ccache);
|
|
if (problem) {}
|
|
else {
|
|
problem = krb5_cc_copy_cache(ssh_context, mem_ccache, ccache);
|
|
if (problem) {}
|
|
}
|
|
|
|
krb5_cc_close(ssh_context, ccache);
|
|
}
|
|
|
|
krb5_cleanup_proc(NULL);
|
|
}
|
|
#endif /* KRB5 */
|
|
|
|
if (xauthfile)
|
|
child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
|
|
if (auth_get_socket_name() != NULL)
|
|
child_set_env(&env, &envsize, SSH_AUTHSOCKET_ENV_NAME,
|
|
auth_get_socket_name());
|
|
|
|
/* read $HOME/.ssh/environment. */
|
|
if (!options.use_login) {
|
|
snprintf(buf, sizeof buf, "%.200s/.ssh/environment", pw->pw_dir);
|
|
read_environment_file(&env, &envsize, buf);
|
|
}
|
|
if (debug_flag) {
|
|
/* dump the environment */
|
|
fprintf(stderr, "Environment:\n");
|
|
for (i = 0; env[i]; i++)
|
|
fprintf(stderr, " %.200s\n", env[i]);
|
|
}
|
|
/*
|
|
* Close the connection descriptors; note that this is the child, and
|
|
* the server will still have the socket open, and it is important
|
|
* that we do not shutdown it. Note that the descriptors cannot be
|
|
* closed before building the environment, as we call
|
|
* get_remote_ipaddr there.
|
|
*/
|
|
if (packet_get_connection_in() == packet_get_connection_out())
|
|
close(packet_get_connection_in());
|
|
else {
|
|
close(packet_get_connection_in());
|
|
close(packet_get_connection_out());
|
|
}
|
|
/*
|
|
* Close all descriptors related to channels. They will still remain
|
|
* open in the parent.
|
|
*/
|
|
/* XXX better use close-on-exec? -markus */
|
|
channel_close_all();
|
|
|
|
/*
|
|
* Close any extra file descriptors. Note that there may still be
|
|
* descriptors left by system functions. They will be closed later.
|
|
*/
|
|
endpwent();
|
|
|
|
/*
|
|
* Close any extra open file descriptors so that we don\'t have them
|
|
* hanging around in clients. Note that we want to do this after
|
|
* initgroups, because at least on Solaris 2.3 it leaves file
|
|
* descriptors open.
|
|
*/
|
|
for (i = 3; i < getdtablesize(); i++)
|
|
close(i);
|
|
|
|
/* Change current directory to the user\'s home directory. */
|
|
if (
|
|
#ifdef __FreeBSD__
|
|
!*pw->pw_dir ||
|
|
#endif /* __FreeBSD__ */
|
|
chdir(pw->pw_dir) < 0
|
|
) {
|
|
#ifdef __FreeBSD__
|
|
int quiet_login = 0;
|
|
#endif /* __FreeBSD__ */
|
|
#ifdef LOGIN_CAP
|
|
if (login_getcapbool(lc, "requirehome", 0)) {
|
|
(void)printf("Home directory not available\n");
|
|
log("LOGIN %.200s REFUSED (HOMEDIR) ON TTY %.200s",
|
|
pw->pw_name, ttyname);
|
|
exit(254);
|
|
}
|
|
#endif /* LOGIN_CAP */
|
|
#ifdef __FreeBSD__
|
|
if (chdir("/") < 0) {
|
|
(void)printf("Cannot find root directory\n");
|
|
log("LOGIN %.200s REFUSED (ROOTDIR) ON TTY %.200s",
|
|
pw->pw_name, ttyname);
|
|
exit(254);
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
quiet_login = login_getcapbool(lc, "hushlogin", 0);
|
|
#endif /* LOGIN_CAP */
|
|
if (!quiet_login || *pw->pw_dir)
|
|
(void)printf(
|
|
"No home directory.\nLogging in with home = \"/\".\n");
|
|
|
|
#else /* !__FreeBSD__ */
|
|
|
|
fprintf(stderr, "Could not chdir to home directory %s: %s\n",
|
|
pw->pw_dir, strerror(errno));
|
|
#endif /* __FreeBSD__ */
|
|
}
|
|
#ifdef LOGIN_CAP
|
|
login_close(lc);
|
|
#endif /* LOGIN_CAP */
|
|
|
|
/*
|
|
* Must take new environment into use so that .ssh/rc, /etc/sshrc and
|
|
* xauth are run in the proper environment.
|
|
*/
|
|
environ = env;
|
|
|
|
/*
|
|
* Run $HOME/.ssh/rc, /etc/sshrc, or xauth (whichever is found first
|
|
* in this order).
|
|
*/
|
|
if (!options.use_login) {
|
|
if (stat(SSH_USER_RC, &st) >= 0) {
|
|
if (debug_flag)
|
|
fprintf(stderr, "Running /bin/sh %s\n", SSH_USER_RC);
|
|
|
|
f = popen("/bin/sh " SSH_USER_RC, "w");
|
|
if (f) {
|
|
if (auth_proto != NULL && auth_data != NULL)
|
|
fprintf(f, "%s %s\n", auth_proto, auth_data);
|
|
pclose(f);
|
|
} else
|
|
fprintf(stderr, "Could not run %s\n", SSH_USER_RC);
|
|
} else if (stat(SSH_SYSTEM_RC, &st) >= 0) {
|
|
if (debug_flag)
|
|
fprintf(stderr, "Running /bin/sh %s\n", SSH_SYSTEM_RC);
|
|
|
|
f = popen("/bin/sh " SSH_SYSTEM_RC, "w");
|
|
if (f) {
|
|
if (auth_proto != NULL && auth_data != NULL)
|
|
fprintf(f, "%s %s\n", auth_proto, auth_data);
|
|
pclose(f);
|
|
} else
|
|
fprintf(stderr, "Could not run %s\n", SSH_SYSTEM_RC);
|
|
}
|
|
#ifdef XAUTH_PATH
|
|
else {
|
|
/* Add authority data to .Xauthority if appropriate. */
|
|
if (auth_proto != NULL && auth_data != NULL) {
|
|
if (debug_flag)
|
|
fprintf(stderr, "Running %.100s add %.100s %.100s %.100s\n",
|
|
XAUTH_PATH, display, auth_proto, auth_data);
|
|
|
|
f = popen(XAUTH_PATH " -q -", "w");
|
|
if (f) {
|
|
fprintf(f, "add %s %s %s\n", display, auth_proto, auth_data);
|
|
pclose(f);
|
|
} else
|
|
fprintf(stderr, "Could not run %s -q -\n", XAUTH_PATH);
|
|
}
|
|
}
|
|
#endif /* XAUTH_PATH */
|
|
|
|
/* Get the last component of the shell name. */
|
|
cp = strrchr(shell, '/');
|
|
if (cp)
|
|
cp++;
|
|
else
|
|
cp = shell;
|
|
}
|
|
/*
|
|
* If we have no command, execute the shell. In this case, the shell
|
|
* name to be passed in argv[0] is preceded by '-' to indicate that
|
|
* this is a login shell.
|
|
*/
|
|
if (!command) {
|
|
if (!options.use_login) {
|
|
char buf[256];
|
|
|
|
/*
|
|
* Check for mail if we have a tty and it was enabled
|
|
* in server options.
|
|
*/
|
|
if (ttyname && options.check_mail) {
|
|
char *mailbox;
|
|
struct stat mailstat;
|
|
mailbox = getenv("MAIL");
|
|
if (mailbox != NULL) {
|
|
if (stat(mailbox, &mailstat) != 0 || mailstat.st_size == 0)
|
|
#ifdef __FreeBSD__
|
|
;
|
|
#else /* !__FreeBSD__ */
|
|
printf("No mail.\n");
|
|
#endif /* __FreeBSD__ */
|
|
else if (mailstat.st_mtime < mailstat.st_atime)
|
|
printf("You have mail.\n");
|
|
else
|
|
printf("You have new mail.\n");
|
|
}
|
|
}
|
|
/* Start the shell. Set initial character to '-'. */
|
|
buf[0] = '-';
|
|
strncpy(buf + 1, cp, sizeof(buf) - 1);
|
|
buf[sizeof(buf) - 1] = 0;
|
|
|
|
/* Execute the shell. */
|
|
argv[0] = buf;
|
|
argv[1] = NULL;
|
|
execve(shell, argv, env);
|
|
|
|
/* Executing the shell failed. */
|
|
perror(shell);
|
|
exit(1);
|
|
|
|
} else {
|
|
/* Launch login(1). */
|
|
|
|
execl("/usr/bin/login", "login", "-h", get_remote_ipaddr(),
|
|
"-p", "-f", "--", pw->pw_name, NULL);
|
|
|
|
/* Login couldn't be executed, die. */
|
|
|
|
perror("login");
|
|
exit(1);
|
|
}
|
|
}
|
|
/*
|
|
* Execute the command using the user's shell. This uses the -c
|
|
* option to execute the command.
|
|
*/
|
|
argv[0] = (char *) cp;
|
|
argv[1] = "-c";
|
|
argv[2] = (char *) command;
|
|
argv[3] = NULL;
|
|
execve(shell, argv, env);
|
|
perror(shell);
|
|
exit(1);
|
|
}
|