Initial revision
diff --git a/sshd.c b/sshd.c
new file mode 100644
index 0000000..059f311
--- /dev/null
+++ b/sshd.c
@@ -0,0 +1,2445 @@
+/*
+
+sshd.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.
+
+*/
+
+#include "includes.h"
+RCSID("$Id: sshd.c,v 1.1 1999/10/27 03:42:46 damien 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"
+
+#ifdef LIBWRAP
+#include <tcpd.h>
+#include <syslog.h>
+int allow_severity = LOG_INFO;
+int deny_severity = LOG_WARNING;
+#endif /* LIBWRAP */
+
+#ifndef O_NOCTTY
+#define O_NOCTTY 0
+#endif
+
+#ifdef KRB4
+char *ticket = NULL;
+#endif /* KRB4 */
+
+#ifdef HAVE_PAM
+#include <security/pam_appl.h>
+struct pam_handle_t *pamh=NULL;
+char *pampasswd=NULL;
+int retval;
+int origretval;
+#endif /* HAVE_PAM */
+
+/* Local Xauthority file. */
+char *xauthfile = NULL;
+
+/* Server configuration options. */
+ServerOptions options;
+
+/* Name of the server configuration file. */
+char *config_file_name = SERVER_CONFIG_FILE;
+
+/* Debug mode flag. This can be set on the command line. If debug
+ mode is enabled, extra debugging output will be sent to the system
+ log, the daemon will not go to background, and will exit after processing
+ the first connection. */
+int debug_flag = 0;
+
+/* Flag indicating that the daemon is being started from inetd. */
+int inetd_flag = 0;
+
+/* argv[0] without path. */
+char *av0;
+
+/* Saved arguments to main(). */
+char **saved_argv;
+
+/* This is set to the socket that the server is listening; this is used in
+ the SIGHUP signal handler. */
+int listen_sock;
+
+/* 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;
+char *forced_command = NULL; /* RSA authentication "command=" option. */
+struct envstring *custom_environment = NULL;
+ /* RSA authentication "environment=" options. */
+
+/* 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
+{
+ /* Private part of server key. */
+ RSA *private_key;
+
+ /* Private part of host key. */
+ RSA *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;
+
+/* Prototypes for various functions defined later in this file. */
+void do_connection(int privileged_port);
+void do_authentication(char *user, int privileged_port);
+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);
+#ifdef HAVE_PAM
+static int pamconv(int num_msg, const struct pam_message **msg,
+ struct pam_response **resp, void *appdata_ptr);
+
+static struct pam_conv conv = {
+ pamconv,
+ NULL
+};
+
+static int pamconv(int num_msg, const struct pam_message **msg,
+ struct pam_response **resp, void *appdata_ptr)
+{
+ int count = 0;
+ int replies = 0;
+ struct pam_response *reply = NULL;
+ int size = sizeof(struct pam_response);
+
+ for(count = 0; count < num_msg; count++)
+ {
+ switch (msg[count]->msg_style)
+ {
+ case PAM_PROMPT_ECHO_ON:
+ case PAM_PROMPT_ECHO_OFF:
+ if (reply == NULL)
+ reply = xmalloc(size);
+ else
+ reply = realloc(reply, size);
+
+ if (reply == NULL)
+ return PAM_CONV_ERR;
+
+ size += sizeof(struct pam_response);
+
+ reply[replies].resp_retcode = PAM_SUCCESS;
+
+ reply[replies++].resp = xstrdup(pampasswd);
+ /* PAM frees resp */
+ break;
+
+ case PAM_TEXT_INFO:
+ /* ignore it... */
+ break;
+
+ case PAM_ERROR_MSG:
+ default:
+ /* Must be an error of some sort... */
+ if (reply != NULL)
+ free(reply);
+
+ return PAM_CONV_ERR;
+ }
+ }
+
+ if (reply != NULL)
+ *resp = reply;
+
+ return PAM_SUCCESS;
+}
+
+void pam_cleanup_proc(void *context)
+{
+ if (retval == PAM_SUCCESS)
+ retval = pam_close_session((pam_handle_t *)pamh, 0);
+
+ if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS)
+ log("Cannot release PAM authentication.");
+}
+#endif /* HAVE_PAM */
+
+/* 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_sock);
+ 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_sock);
+ 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;
+ wait(&status);
+ 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.");
+}
+
+/* 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, aux, sock_in, sock_out, newsock, i, pid, on = 1;
+ int remote_major, remote_minor;
+ int silentrsa = 0;
+ struct sockaddr_in sin;
+ char buf[100]; /* Must not be larger than remote_version. */
+ char remote_version[100]; /* Must be at least as big as buf. */
+ char *comment;
+ FILE *f;
+ struct linger linger;
+
+ /* 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:diqQ")) != EOF)
+ {
+ switch (opt)
+ {
+ case 'f':
+ config_file_name = optarg;
+ break;
+ case 'd':
+ debug_flag = 1;
+ break;
+ case 'i':
+ inetd_flag = 1;
+ break;
+ case 'Q':
+ silentrsa = 1;
+ break;
+ case 'q':
+ options.quiet_mode = 1;
+ break;
+ case 'b':
+ options.server_key_bits = atoi(optarg);
+ break;
+ case 'p':
+ 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 '?':
+ 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/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, " -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);
+ exit(1);
+ }
+ }
+
+ /* 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);
+ }
+ if (options.port < 1 || options.port > 65535)
+ {
+ fprintf(stderr, "Bad port number.\n");
+ exit(1);
+ }
+
+ /* Check that there are no remaining arguments. */
+ if (optind < ac)
+ {
+ fprintf(stderr, "Extra argument %s.\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", SSH_VERSION);
+
+ sensitive_data.host_key = RSA_new();
+ /* Load the host key. It must have empty passphrase. */
+ if (!load_private_key(options.host_key_file, "",
+ sensitive_data.host_key, &comment))
+ {
+ if (debug_flag)
+ fprintf(stderr, "Could not load host key: %s: %s\n",
+ options.host_key_file, strerror(errno));
+ else
+ {
+ int err = errno;
+ log_init(av0, !inetd_flag, 1, 0, options.log_facility);
+ error("Could not load host key: %.200s: %.100s",
+ options.host_key_file, strerror(err));
+ }
+ 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 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, 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. 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("/");
+
+ /* Close connection cleanly after attack. */
+ cipher_attack_detected = packet_disconnect;
+
+ /* 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();
+ /* Generate an rsa key. */
+ 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
+ {
+ /* Create socket for listening. */
+ listen_sock = socket(AF_INET, SOCK_STREAM, 0);
+ 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));
+ linger.l_onoff = 1;
+ linger.l_linger = 5;
+ setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, (void *)&linger,
+ sizeof(linger));
+
+ /* Initialize the socket address. */
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+ sin.sin_addr = options.listen_addr;
+ sin.sin_port = htons(options.port);
+
+ /* 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, SHUT_RDWR);
+ close(listen_sock);
+ fatal("Bind to port %d failed.", options.port);
+ }
+
+ 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);
+ }
+ }
+
+ /* Start listening on the port. */
+ log("Server listening on port %d.", options.port);
+ if (listen(listen_sock, 5) < 0)
+ fatal("listen: %.100s", strerror(errno));
+
+ public_key = RSA_new();
+ sensitive_data.private_key = RSA_new();
+ /* Generate an rsa key. */
+ 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);
+
+ /* Stay listening for connections until the system crashes or the
+ daemon is killed with a signal. */
+ for (;;)
+ {
+ if (received_sighup)
+ sighup_restart();
+ /* Wait in accept until there is a connection. */
+ aux = sizeof(sin);
+ newsock = accept(listen_sock, (struct sockaddr *)&sin, &aux);
+ if (received_sighup)
+ sighup_restart();
+ 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();
+ 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 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;
+ 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;
+
+ arc4random_stir();
+
+ /* 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)); */
+ 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);
+
+ /* 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);
+ }
+ log("Connection from %.500s port %d",
+ eval_client(&req), get_remote_port());
+ }
+#else
+ /* Log the connection. */
+ log("Connection from %.100s port %d",
+ get_remote_ipaddr(), get_remote_port());
+#endif /* LIBWRAP */
+
+ /* 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);
+
+ /* Send our protocol version identification. */
+ snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
+ PROTOCOL_MAJOR, PROTOCOL_MINOR, SSH_VERSION);
+ if (write(sock_out, buf, strlen(buf)) != strlen(buf))
+ fatal("Could not write ident string.");
+
+ /* Read other side\'s version identification. */
+ for (i = 0; i < sizeof(buf) - 1; i++)
+ {
+ if (read(sock_in, &buf[i], 1) != 1)
+ fatal("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;
+
+ /* 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("Bad protocol version identification: %.100s", buf);
+ }
+ debug("Client protocol version %d.%d; client software version %.100s",
+ remote_major, remote_minor, remote_version);
+ if (remote_major != PROTOCOL_MAJOR)
+ {
+ const char *s = "Protocol major versions differ.\n";
+ (void) write(sock_out, s, strlen(s));
+ close(sock_in);
+ close(sock_out);
+ fatal("Protocol major versions differ: %d vs. %d",
+ PROTOCOL_MAJOR, remote_major);
+ }
+
+ /* 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) {
+ enable_compat13();
+ if (strcmp(remote_version, "OpenSSH-1.1") != 0) {
+ debug("Agent forwarding disabled, remote version is not compatible.");
+ no_agent_forwarding_flag = 1;
+ }
+ }
+
+ packet_set_nonblocking();
+
+ /* Handle the connection. We pass as argument whether the connection
+ came from a privileged port. */
+ do_connection(get_remote_port() < IPPORT_RESERVED);
+
+#ifdef KRB4
+ /* Cleanup user's ticket cache file. */
+ if (options.kerberos_ticket_cleanup)
+ (void) dest_tkt();
+#endif /* KRB4 */
+
+ /* Cleanup user's local Xauthority file. */
+ if (xauthfile) unlink(xauthfile);
+
+ /* The connection has been terminated. */
+ log("Closing connection to %.100s", inet_ntoa(sin.sin_addr));
+
+#ifdef HAVE_PAM
+ if (retval == PAM_SUCCESS)
+ retval = pam_close_session((pam_handle_t *)pamh, 0);
+
+ if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS)
+ log("Cannot release PAM authentication.");
+
+ fatal_remove_cleanup(&pam_cleanup_proc, NULL);
+#endif /* HAVE_PAM */
+
+ packet_close();
+
+ exit(0);
+}
+
+/* Process an incoming connection. Protocol version identifiers have already
+ been exchanged. This sends server key and performs the key exchange.
+ Server and host keys will no longer be needed after this functions. */
+
+void do_connection(int privileged_port)
+{
+ int i;
+ BIGNUM *session_key_int;
+ unsigned char session_key[SSH_SESSION_KEY_LENGTH];
+ unsigned char check_bytes[8];
+ char *user;
+ unsigned int cipher_type, auth_mask, protocol_flags;
+ int plen, slen;
+ 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();
+ check_bytes[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(check_bytes[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.kerberos_authentication)
+ auth_mask |= 1 << SSH_AUTH_KERBEROS;
+#endif
+#ifdef AFS
+ if (options.kerberos_tgt_passing)
+ auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
+ if (options.afs_token_passing)
+ auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
+#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. */
+ cipher_type = packet_get_char();
+
+ /* 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 (check_bytes[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);
+
+ /* Get protocol flags. */
+ 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. */
+ assert(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). */
+ assert(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 for this session. */
+ compute_session_id(session_id, check_bytes,
+ BN_num_bits(sensitive_data.host_key->n),
+ sensitive_data.host_key->n,
+ BN_num_bits(sensitive_data.private_key->n),
+ sensitive_data.private_key->n);
+
+ /* 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);
+ assert(BN_num_bytes(session_key_int) == sizeof(session_key));
+ BN_bn2bin(session_key_int, session_key);
+
+ /* 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];
+
+ /* Destroy the decrypted integer. It is no longer needed. */
+ BN_clear_free(session_key_int);
+
+ /* Set the session key. From this on all communications will be
+ encrypted. */
+ packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH,
+ cipher_type, 0);
+
+ /* 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();
+
+ /* Get the name of the user that we wish to log in as. */
+ packet_read_expect(&plen, SSH_CMSG_USER);
+
+ /* Get the user name. */
+ {
+ int ulen;
+ user = packet_get_string(&ulen);
+ packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
+ }
+
+ /* 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);
+
+ setproctitle("%s", user);
+ /* Do the authentication. */
+ do_authentication(user, privileged_port);
+}
+
+/* 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. Otherwise true is returned.
+ XXX This function should also check if user has a valid shell */
+
+static int
+allowed_user(struct passwd *pw)
+{
+ struct group *grp;
+ int i;
+
+ /* Shouldn't be called if pw is NULL, but better safe than sorry... */
+ if (!pw)
+ return 0;
+
+ /* XXX Should check for valid login shell */
+
+ /* 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;
+ }
+ }
+
+ /* 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. User is the user name to log
+ in as (received from the clinet). Privileged_port is true if the
+ connection comes from a privileged port (used for .rhosts authentication).*/
+
+#define MAX_AUTH_FAILURES 5
+
+void
+do_authentication(char *user, int privileged_port)
+{
+ int type;
+ int authenticated = 0;
+ int authentication_failures = 0;
+ char *password;
+ struct passwd *pw, pwcopy;
+ char *client_user;
+ unsigned int client_host_key_bits;
+ BIGNUM *client_host_key_e, *client_host_key_n;
+#ifdef HAVE_PAM
+ int pam_auth_ok;
+#endif /* HAVE_PAM */
+
+#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);
+#ifdef HAVE_PAM
+ if ((pw != NULL) && allowed_user(pw))
+ {
+ /* Initialise PAM */
+ retval = pam_start("ssh", pw->pw_name, &conv, (pam_handle_t **)&pamh);
+ fatal_add_cleanup(&pam_cleanup_proc, NULL);
+ origretval = retval;
+ if (retval == PAM_SUCCESS)
+ pam_auth_ok = 1;
+ }
+
+ if (pam_auth_ok == 0)
+#else /* HAVE_PAM */
+ if (!pw || !allowed_user(pw))
+#endif /* HAVE_PAM */
+ {
+ /* The user does not exist or access is denied,
+ but fake indication 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 (;;)
+ {
+ /* Read a packet. This will not return if the client disconnects. */
+ int plen;
+ int type = packet_read(&plen);
+#ifdef SKEY
+ int passw_len;
+ char *password, *skeyinfo;
+ if (options.password_authentication &&
+ options.skey_authentication == 1 &&
+ type == SSH_CMSG_AUTH_PASSWORD &&
+ (password = packet_get_string(&passw_len)) != NULL &&
+ passw_len == 5 &&
+ strncasecmp(password, "s/key", 5) == 0 &&
+ (skeyinfo = skey_fake_keyinfo(user)) != NULL ){
+ /* Send a fake s/key challenge. */
+ packet_send_debug(skeyinfo);
+ }
+#endif
+ /* Send failure. This should be indistinguishable from a failed
+ authentication. */
+ packet_start(SSH_SMSG_FAILURE);
+ packet_send();
+ packet_write_wait();
+ if (++authentication_failures >= MAX_AUTH_FAILURES) {
+ packet_disconnect("Too many authentication failures for %.100s from %.200s",
+ user, get_canonical_hostname());
+ }
+ }
+ /*NOTREACHED*/
+ abort();
+ }
+
+ /* 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);
+ 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.", user);
+
+ /* If the user has no password, accept authentication immediately. */
+ if (options.password_authentication &&
+#ifdef KRB4
+ (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
+#endif /* KRB4 */
+ auth_password(pw, ""))
+ {
+ /* Authentication with empty password succeeded. */
+ debug("Login for user %.100s accepted without authentication.", user);
+ /* authentication_type = SSH_AUTH_PASSWORD; */
+ authenticated = 1;
+ /* Success packet will be sent after loop below. */
+ }
+ else
+ {
+ /* Indicate that authentication is needed. */
+ packet_start(SSH_SMSG_FAILURE);
+ packet_send();
+ packet_write_wait();
+ }
+
+ /* Loop until the user has been authenticated or the connection is closed. */
+ while (!authenticated)
+ {
+ int plen;
+ /* Get a packet from the client. */
+ type = packet_read(&plen);
+
+ /* Process the packet. */
+ switch (type)
+ {
+
+#ifdef AFS
+ case SSH_CMSG_HAVE_KERBEROS_TGT:
+ if (!options.kerberos_tgt_passing)
+ {
+ /* packet_get_all(); */
+ log("Kerberos tgt passing disabled.");
+ break;
+ }
+ else {
+ /* Accept Kerberos tgt. */
+ int dlen;
+ char *tgt = packet_get_string(&dlen);
+ packet_integrity_check(plen, 4 + dlen, type);
+ if (!auth_kerberos_tgt(pw, tgt))
+ debug("Kerberos tgt REFUSED for %s", user);
+ xfree(tgt);
+ }
+ continue;
+
+ case SSH_CMSG_HAVE_AFS_TOKEN:
+ if (!options.afs_token_passing || !k_hasafs()) {
+ /* packet_get_all(); */
+ log("AFS token passing disabled.");
+ break;
+ }
+ else {
+ /* Accept AFS token. */
+ int dlen;
+ char *token_string = packet_get_string(&dlen);
+ packet_integrity_check(plen, 4 + dlen, type);
+ if (!auth_afs_token(user, pw->pw_uid, token_string))
+ debug("AFS token REFUSED for %s", user);
+ xfree(token_string);
+ continue;
+ }
+#endif /* AFS */
+
+#ifdef KRB4
+ case SSH_CMSG_AUTH_KERBEROS:
+ if (!options.kerberos_authentication)
+ {
+ /* packet_get_all(); */
+ log("Kerberos 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);
+
+ if (auth_krb4(user, &auth, &tkt_user)) {
+ /* Client has successfully authenticated to us. */
+ log("Kerberos authentication accepted %s for account "
+ "%s from %s", tkt_user, user, get_canonical_hostname());
+ /* authentication_type = SSH_AUTH_KERBEROS; */
+ authenticated = 1;
+ xfree(tkt_user);
+ }
+ else {
+ log("Kerberos authentication failed for account "
+ "%s from %s", user, get_canonical_hostname());
+ }
+ }
+ break;
+#endif /* KRB4 */
+
+ case SSH_CMSG_AUTH_RHOSTS:
+ if (!options.rhosts_authentication)
+ {
+ log("Rhosts authentication disabled.");
+ break;
+ }
+
+ /* Rhosts authentication (also uses /etc/hosts.equiv). */
+ if (!privileged_port)
+ {
+ log("Rhosts authentication not available for connections from unprivileged port.");
+ 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.) */
+ {
+ int dlen;
+ client_user = packet_get_string(&dlen);
+ packet_integrity_check(plen, 4 + dlen, type);
+ }
+
+ /* Try to authenticate using /etc/hosts.equiv and .rhosts. */
+ if (auth_rhosts(pw, client_user, options.ignore_rhosts,
+ options.strict_modes))
+ {
+ /* Authentication accepted. */
+ log("Rhosts authentication accepted for %.100s, remote %.100s on %.700s.",
+ user, client_user, get_canonical_hostname());
+ authenticated = 1;
+ xfree(client_user);
+ break;
+ }
+ log("Rhosts authentication failed for %.100s, remote %.100s.",
+ user, client_user);
+ xfree(client_user);
+ break;
+
+ case SSH_CMSG_AUTH_RHOSTS_RSA:
+ if (!options.rhosts_rsa_authentication)
+ {
+ log("Rhosts with RSA authentication disabled.");
+ break;
+ }
+
+ /* Rhosts authentication (also uses /etc/hosts.equiv) with RSA
+ host authentication. */
+ if (!privileged_port)
+ {
+ log("Rhosts authentication not available for connections from unprivileged port.");
+ break;
+ }
+
+ {
+ int ulen, elen, nlen;
+ /* 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_e = BN_new();
+ client_host_key_n = BN_new();
+ client_host_key_bits = packet_get_int();
+ packet_get_bignum(client_host_key_e, &elen);
+ packet_get_bignum(client_host_key_n, &nlen);
+
+ packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
+ }
+
+ /* Try to authenticate using /etc/hosts.equiv and .rhosts. */
+ if (auth_rhosts_rsa(pw, client_user,
+ client_host_key_bits, client_host_key_e,
+ client_host_key_n, options.ignore_rhosts,
+ options.strict_modes))
+ {
+ /* Authentication accepted. */
+ authenticated = 1;
+ xfree(client_user);
+ BN_clear_free(client_host_key_e);
+ BN_clear_free(client_host_key_n);
+ break;
+ }
+ log("Rhosts authentication failed for %.100s, remote %.100s.",
+ user, client_user);
+ xfree(client_user);
+ BN_clear_free(client_host_key_e);
+ BN_clear_free(client_host_key_n);
+ break;
+
+ case SSH_CMSG_AUTH_RSA:
+ if (!options.rsa_authentication)
+ {
+ log("RSA authentication disabled.");
+ break;
+ }
+
+ /* RSA authentication requested. */
+ {
+ int nlen;
+ BIGNUM *n;
+ n = BN_new();
+ packet_get_bignum(n, &nlen);
+
+ packet_integrity_check(plen, nlen, type);
+
+ if (auth_rsa(pw, n, options.strict_modes))
+ {
+ /* Successful authentication. */
+ BN_clear_free(n);
+ log("RSA authentication for %.100s accepted.", user);
+ authenticated = 1;
+ break;
+ }
+ BN_clear_free(n);
+ log("RSA authentication for %.100s failed.", user);
+ }
+ break;
+
+ case SSH_CMSG_AUTH_PASSWORD:
+ if (!options.password_authentication)
+ {
+ log("Password authentication disabled.");
+ break;
+ }
+
+ /* Password authentication requested. */
+ /* Read user password. It is in plain text, but was transmitted
+ over the encrypted channel so it is not visible to an outside
+ observer. */
+ {
+ int passw_len;
+ password = packet_get_string(&passw_len);
+ packet_integrity_check(plen, 4 + passw_len, type);
+ }
+
+ /* Try authentication with the password. */
+ if (auth_password(pw, password))
+ {
+ /* Successful authentication. */
+ /* Clear the password from memory. */
+ memset(password, 0, strlen(password));
+ xfree(password);
+ log("Password authentication for %.100s accepted.", user);
+ authenticated = 1;
+ break;
+ }
+ log("Password authentication for %.100s failed.", user);
+ memset(password, 0, strlen(password));
+ xfree(password);
+ break;
+
+ case SSH_CMSG_AUTH_TIS:
+ /* TIS Authentication is unsupported */
+ log("TIS authentication disabled.");
+ break;
+
+ default:
+ /* Any unknown messages will be ignored (and failure returned)
+ during authentication. */
+ log("Unknown message during authentication: type %d", type);
+ break; /* Respond with a failure message. */
+ }
+ /* If successfully authenticated, break out of loop. */
+ if (authenticated)
+ break;
+
+ /* Send a message indicating that the authentication attempt failed. */
+ packet_start(SSH_SMSG_FAILURE);
+ packet_send();
+ packet_write_wait();
+
+ if (++authentication_failures >= MAX_AUTH_FAILURES) {
+ packet_disconnect("Too many authentication failures for %.100s from %.200s",
+ pw->pw_name, get_canonical_hostname());
+ }
+ }
+
+ /* 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.", forced_command);
+ else
+ packet_disconnect("ROOT LOGIN REFUSED FROM %.200s",
+ 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);
+}
+
+/* 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, xauthfd = -1;
+ int row, col, xpixel, ypixel, screen;
+ char ttyname[64];
+ char *command, *term = NULL, *display = NULL, *proto = NULL, *data = NULL;
+ struct group *grp;
+ gid_t tty_gid;
+ mode_t tty_mode;
+ 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.) */
+ channel_permit_all_opens();
+
+ /* We stay in this loop until the client requests to execute a shell or a
+ command. */
+ while (1)
+ {
+ int plen, dlen;
+
+ /* 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))
+ {
+ error("Failed to allocate pty.");
+ goto fail;
+ }
+
+ /* Determine the group to make the owner of the tty. */
+ grp = getgrnam("tty");
+ if (grp)
+ {
+ tty_gid = grp->gr_gid;
+ tty_mode = S_IRUSR|S_IWUSR|S_IWGRP;
+ }
+ else
+ {
+ tty_gid = pw->pw_gid;
+ tty_mode = S_IRUSR|S_IWUSR|S_IWGRP|S_IWOTH;
+ }
+
+ /* Change ownership of the tty. */
+ if (chown(ttyname, pw->pw_uid, tty_gid) < 0)
+ fatal("chown(%.100s, %d, %d) failed: %.100s",
+ ttyname, pw->pw_uid, tty_gid, strerror(errno));
+ if (chmod(ttyname, tty_mode) < 0)
+ fatal("chmod(%.100s, 0%o) failed: %.100s",
+ ttyname, tty_mode, strerror(errno));
+
+ /* 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);
+ /* packet_integrity_check(plen, 4 + dlen + 4*4 + n_bytes, type); */
+ /* Remaining bytes */
+ n_bytes = plen - (4 + dlen + 4*4);
+
+ if (strcmp(term, "") == 0)
+ 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.");
+ {
+ 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);
+ if (!display)
+ goto fail;
+
+ /* Setup to always have a local .Xauthority. */
+ xauthfile = xmalloc(MAXPATHLEN);
+ snprintf(xauthfile, MAXPATHLEN, "/tmp/XauthXXXXXX");
+
+ if ((xauthfd = mkstemp(xauthfile)) != -1) {
+ fchown(xauthfd, pw->pw_uid, pw->pw_gid);
+ close(xauthfd);
+ }
+ else {
+ xfree(xauthfile);
+ xauthfile = NULL;
+ }
+ break;
+#else /* XAUTH_PATH */
+ /* No xauth program; we won't accept forwarding with spoofing. */
+ 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)
+ {
+ 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_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. */
+ {
+ 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;
+
+ case SSH_CMSG_MAX_PACKET_SIZE:
+ debug("The server does not support limiting packet size.");
+ goto fail;
+
+ 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, debug_flag && !inetd_flag, debug_flag,
+ options.quiet_mode, options.log_facility);
+
+ /* 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 */
+}
+
+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");
+
+#if defined(KRB4)
+ /* Destroy user's ticket cache file. */
+ (void) dest_tkt();
+#endif /* KRB4 */
+
+ /* Record that the user has logged out. */
+ record_logout(cu->pid, cu->ttyname);
+
+ /* Release the pseudo-tty. */
+ pty_release(cu->ttyname);
+}
+
+/* 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;
+ 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_in from;
+ int fromlen;
+ struct pty_cleanup_context cleanup_context;
+
+ /* 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, debug_flag && !inetd_flag, debug_flag, options.quiet_mode,
+ options.log_facility);
+
+ /* 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)
+ fatal("getpeername: %.100s", strerror(errno));
+ }
+
+ /* Record that there was a login on that terminal. */
+ record_login(pid, ttyname, pw->pw_name, pw->pw_uid, hostname,
+ &from);
+
+ /* Check if .hushlogin exists. */
+ snprintf(line, sizeof line, "%.200s/.hushlogin", pw->pw_dir);
+ quiet_login = stat(line, &st) >= 0;
+
+ /* 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);
+ }
+
+ /* 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)
+ {
+ /* Print /etc/motd if it exists. */
+ f = fopen("/etc/motd", "r");
+ if (f)
+ {
+ while (fgets(line, sizeof(line), f))
+ fputs(line, stdout);
+ fclose(f);
+ }
+ }
+
+ /* 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);
+
+ /* 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 failed: %.100s", strerror(errno));
+
+ /* 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);
+
+ /* Enter interactive session. */
+ server_loop(pid, ptyfd, fdout, -1);
+ /* server_loop has not 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. */
+ close(ptyfd);
+ close(fdout);
+}
+
+/* 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])
+ {
+ /* Name already exists. Reuse the slot. */
+ xfree(env[i]);
+ }
+ else
+ {
+ /* New variable. Expand the array 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;
+
+ /* Open the environment file. */
+ f = fopen(filename, "r");
+ if (!f)
+ return; /* Not found. */
+
+ /* Process each line. */
+ while (fgets(buf, sizeof(buf), f))
+ {
+ /* Skip leading whitespace. */
+ for (cp = buf; *cp == ' ' || *cp == '\t'; cp++)
+ ;
+
+ /* Ignore empty and comment lines. */
+ if (!*cp || *cp == '#' || *cp == '\n')
+ continue;
+
+ /* Remove newline. */
+ if (strchr(cp, '\n'))
+ *strchr(cp, '\n') = '\0';
+
+ /* Find the equals sign. Its lack indicates badly formatted line. */
+ 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++;
+
+ /* Set the value in environment. */
+ 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)
+{
+ const char *shell, *cp = NULL;
+ char buf[256];
+ FILE *f;
+ unsigned int envsize, i;
+ char **env;
+ extern char **environ;
+ struct stat st;
+ char *argv[10];
+
+ /* Check /etc/nologin. */
+ 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);
+ }
+
+ /* 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) {
+ 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);
+ }
+
+ /* 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 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. In the first part we allocate space for
+ all environment variables. */
+ 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);
+ 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);
+
+ /* Normal systems set SHELL by default. */
+ child_set_env(&env, &envsize, "SHELL", shell);
+ }
+
+ /* Let it inherit timezone if we have one. */
+ 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);
+ }
+
+ /* Set SSH_CLIENT. */
+ snprintf(buf, sizeof buf, "%.50s %d %d",
+ get_remote_ipaddr(), get_remote_port(), options.port);
+ child_set_env(&env, &envsize, "SSH_CLIENT", buf);
+
+ /* Set SSH_TTY if we have a pty. */
+ if (ttyname)
+ child_set_env(&env, &envsize, "SSH_TTY", ttyname);
+
+ /* Set TERM if we have a pty. */
+ if (term)
+ child_set_env(&env, &envsize, "TERM", term);
+
+ /* Set DISPLAY if we have one. */
+ if (display)
+ child_set_env(&env, &envsize, "DISPLAY", display);
+
+#ifdef KRB4
+ if (ticket)
+ child_set_env(&env, &envsize, "KRBTKFILE", ticket);
+#endif /* KRB4 */
+
+ /* Set XAUTHORITY to always be a local file. */
+ if (xauthfile)
+ child_set_env(&env, &envsize, "XAUTHORITY", xauthfile);
+
+ /* Set variable for forwarded authentication connection, if we have one. */
+ 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 debugging, dump the environment to stderr. */
+ if (debug_flag)
+ {
+ 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. */
+ 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();
+ endhostent();
+
+ /* 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 < 64; i++)
+ close(i);
+
+ /* Change current directory to the user\'s home directory. */
+ if (chdir(pw->pw_dir) < 0)
+ fprintf(stderr, "Could not chdir to home directory %s: %s\n",
+ pw->pw_dir, strerror(errno));
+
+ /* 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);
+ fclose(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) {
+ printf("No mail.\n");
+ } 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);
+}