/*
-
-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.
-
-*/
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ * All rights reserved
+ * This program is the ssh daemon. It listens for connections from clients,
+ * and performs authentication, executes use commands or shell, and forwards
+ * information to/from the application to the user client over an encrypted
+ * connection. This can also handle forwarding of X11, TCP/IP, and
+ * authentication agent connections.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose. Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ * SSH2 implementation:
+ *
+ * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
#include "includes.h"
-RCSID("$Id$");
+RCSID("$OpenBSD: sshd.c,v 1.128 2000/09/17 15:38:59 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 "buffer.h"
+
+#include "ssh2.h"
+#include <openssl/dh.h>
+#include <openssl/bn.h>
+#include <openssl/hmac.h>
+#include "kex.h"
+#include <openssl/dsa.h>
+#include <openssl/rsa.h>
+#include "key.h"
+#include "dsa.h"
+
+#include "auth.h"
+#include "myproposal.h"
+#include "authfile.h"
#ifdef LIBWRAP
#include <tcpd.h>
#define O_NOCTTY 0
#endif
-/* 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;
-/* 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. */
+/*
+ * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
+ * Default value is AF_UNSPEC means both IPv4 and IPv6.
+ */
+#ifdef IPV4_DEFAULT
+int IPv4or6 = AF_INET;
+#else
+int IPv4or6 = AF_UNSPEC;
+#endif
+
+/*
+ * 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. */
/* Saved arguments to main(). */
char **saved_argv;
+int saved_argc;
-/* 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];
+/*
+ * 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;
-/* 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;
+/*
+ * the client's version string, passed by sshd2 in compat mode. if != NULL,
+ * sshd will skip the version-number exchange
+ */
+char *client_version_string = NULL;
+char *server_version_string = NULL;
- /* Private part of host key. */
- RSA *host_key;
+/*
+ * 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 empheral server key. */
+ RSA *host_key; /* Private part of host key. */
+ Key *dsa_host_key; /* Private DSA 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. */
+/*
+ * 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. */
the private key. */
RSA *public_key;
+/* session identifier, used by RSA-auth */
+unsigned char session_id[16];
+
+/* same for ssh2 */
+unsigned char *session_id2 = NULL;
+int session_id2_len = 0;
+
+/* record remote hostname or ip */
+unsigned int utmp_len = MAXHOSTNAMELEN;
+
/* Prototypes for various functions defined later in this file. */
-void do_connection(int privileged_port);
-void do_authentication(char *user, int privileged_port);
-void eat_packets_and_disconnect(const 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);
-#ifdef HAVE_LIBPAM
-static int pamconv(int num_msg, const struct pam_message **msg,
- struct pam_response **resp, void *appdata_ptr);
-void do_pam_account_and_session(const char *username, const char *password,
- const char *remote_user, const char *remote_host);
-void pam_cleanup_proc(void *context);
-
-static struct pam_conv conv = {
- pamconv,
- NULL
-};
-struct pam_handle_t *pamh = NULL;
-const char *pampasswd = NULL;
-char *pamconv_msg = NULL;
-
-static int pamconv(int num_msg, const struct pam_message **msg,
- struct pam_response **resp, void *appdata_ptr)
-{
- int count = 0;
- struct pam_response *reply = NULL;
-
- /* PAM will free this later */
- reply = malloc(num_msg * sizeof(*reply));
- if (reply == NULL)
- return PAM_CONV_ERR;
-
- for(count = 0; count < num_msg; count++)
- {
- switch (msg[count]->msg_style)
- {
- case PAM_PROMPT_ECHO_OFF:
- if (pampasswd == NULL)
- {
- free(reply);
- return PAM_CONV_ERR;
- }
- reply[count].resp_retcode = PAM_SUCCESS;
- reply[count].resp = xstrdup(pampasswd);
- break;
-
- case PAM_TEXT_INFO:
- reply[count].resp_retcode = PAM_SUCCESS;
- reply[count].resp = xstrdup("");
-
- if (msg[count]->msg == NULL) break;
- debug("Adding PAM message: %s", msg[count]->msg);
- if (pamconv_msg == NULL)
- {
- pamconv_msg = malloc(strlen(msg[count]->msg) + 2);
-
- if (pamconv_msg == NULL)
- return PAM_CONV_ERR;
-
- strncpy(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg));
- pamconv_msg[strlen(msg[count]->msg)] = '\n';
- pamconv_msg[strlen(msg[count]->msg) + 1] = '\0';
- } else
- {
- pamconv_msg = realloc(pamconv_msg, strlen(pamconv_msg) + strlen(msg[count]->msg) + 2);
- strncat(pamconv_msg, msg[count]->msg, strlen(msg[count]->msg));
- pamconv_msg[strlen(pamconv_msg)] = '\n';
- pamconv_msg[strlen(pamconv_msg) + 1] = '\0';
- }
- break;
-
- case PAM_PROMPT_ECHO_ON:
- case PAM_ERROR_MSG:
- default:
- free(reply);
- return PAM_CONV_ERR;
- }
- }
-
- *resp = reply;
-
- return PAM_SUCCESS;
-}
+void do_ssh1_kex();
+void do_ssh2_kex();
-void pam_cleanup_proc(void *context)
+/*
+ * Close all listening sockets
+ */
+void
+close_listen_socks(void)
{
- int pam_retval;
-
- if (pamh != NULL)
- {
- pam_retval = pam_close_session((pam_handle_t *)pamh, 0);
- if (pam_retval != PAM_SUCCESS)
- {
- log("Cannot close PAM session: %.200s",
- pam_strerror((pam_handle_t *)pamh, pam_retval));
- }
-
- pam_retval = pam_end((pam_handle_t *)pamh, pam_retval);
- if (pam_retval != PAM_SUCCESS)
- {
- log("Cannot release PAM authentication: %.200s",
- pam_strerror((pam_handle_t *)pamh, pam_retval));
- }
- }
+ int i;
+ for (i = 0; i < num_listen_socks; i++)
+ close(listen_socks[i]);
+ num_listen_socks = -1;
}
-void do_pam_account_and_session(const char *username, const char *password, const char *remote_user, const char *remote_host)
+/*
+ * 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)
{
- int pam_retval;
-
- if (remote_host != NULL)
- {
- debug("PAM setting rhost to \"%.200s\"", remote_host);
- pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RHOST, remote_host);
- if (pam_retval != PAM_SUCCESS)
- {
- log("PAM set rhost failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval));
- eat_packets_and_disconnect(username);
- }
- }
-
- if (remote_user != NULL)
- {
- debug("PAM setting ruser to \"%.200s\"", remote_user);
- pam_retval = pam_set_item((pam_handle_t *)pamh, PAM_RUSER, remote_user);
- if (pam_retval != PAM_SUCCESS)
- {
- log("PAM set ruser failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval));
- eat_packets_and_disconnect(username);
- }
- }
-
- pam_retval = pam_acct_mgmt((pam_handle_t *)pamh, 0);
- if (pam_retval != PAM_SUCCESS)
- {
- log("PAM rejected by account configuration: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval));
- eat_packets_and_disconnect(username);
- }
-
- pam_retval = pam_open_session((pam_handle_t *)pamh, 0);
- if (pam_retval != PAM_SUCCESS)
- {
- log("PAM session setup failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval));
- eat_packets_and_disconnect(username);
- }
+ received_sighup = 1;
+ signal(SIGHUP, sighup_handler);
}
-#endif /* HAVE_LIBPAM */
-/* 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)
+/*
+ * Called from the main program after receiving SIGHUP.
+ * Restarts the server.
+ */
+void
+sighup_restart()
{
- received_sighup = 1;
- signal(SIGHUP, sighup_handler);
+ 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);
}
-/* Called from the main program after receiving SIGHUP. Restarts the
- server. */
-
-void sighup_restart()
+/*
+ * 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 SIGHUP; restarting.");
- close(listen_sock);
- execv(saved_argv[0], saved_argv);
- log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno));
- exit(1);
+ log("Received signal %d; terminating.", sig);
+ close_listen_socks();
+ unlink(options.pid_file);
+ exit(255);
}
-/* 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)
+/*
+ * 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)
{
- log("Received signal %d; terminating.", sig);
- close(listen_sock);
- exit(255);
-}
+ int save_errno = errno;
+ int status;
-/* SIGCHLD handler. This is called whenever a child dies. This will then
- reap any zombies left by exited c. */
+ while (waitpid(-1, &status, WNOHANG) > 0)
+ ;
-void main_sigchld_handler(int sig)
-{
- int save_errno = errno;
- int status;
- wait(&status);
- signal(SIGCHLD, main_sigchld_handler);
- errno = save_errno;
+ 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)
+/*
+ * 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. */
+ /* Close the connection. */
+ packet_close();
-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;
+ /* Log error and exit. */
+ fatal("Timeout before authentication for %s.", get_remote_ipaddr());
}
-/* Main program for the daemon. */
-
-int
-main(int ac, char **av)
+/*
+ * 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.
+ */
+/* XXX do we really want this work to be done in a signal handler ? -m */
+void
+key_regeneration_alarm(int sig)
{
- 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;
- 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.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). */
-
- if (debug_flag && !inetd_flag)
- log_stderr = 1;
-
- log_init(av0, options.log_level, options.log_facility, log_stderr);
-
- 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;
- /* force logging */
- log_init(av0, SYSLOG_LEVEL_DEBUG, options.log_facility, log_stderr);
- 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, 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("/");
-
- /* 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);
+ 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;
+}
- 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);
- }
+void
+sshd_exchange_identification(int sock_in, int sock_out)
+{
+ int i, mismatch;
+ int remote_major, remote_minor;
+ int major, minor;
+ char *s;
+ char buf[256]; /* Must not be larger than remote_version. */
+ char remote_version[256]; /* Must be at least as big as buf. */
+
+ if ((options.protocol & SSH_PROTO_1) &&
+ (options.protocol & SSH_PROTO_2)) {
+ major = PROTOCOL_MAJOR_1;
+ minor = 99;
+ } else if (options.protocol & SSH_PROTO_2) {
+ major = PROTOCOL_MAJOR_2;
+ minor = PROTOCOL_MINOR_2;
+ } else {
+ major = PROTOCOL_MAJOR_1;
+ minor = PROTOCOL_MINOR_1;
}
-
- /* 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, options.log_level, options.log_facility, log_stderr);
- break;
+ snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
+ server_version_string = xstrdup(buf);
+
+ if (client_version_string == NULL) {
+ /* Send our protocol version identification. */
+ if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
+ != strlen(server_version_string)) {
+ log("Could not write ident string to %s.", get_remote_ipaddr());
+ fatal_cleanup();
}
- }
-
- /* 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);
+ /* Read other side\'s version identification. */
+ for (i = 0; i < sizeof(buf) - 1; i++) {
+ if (atomicio(read, sock_in, &buf[i], 1) != 1) {
+ log("Did not receive ident string from %s.", get_remote_ipaddr());
+ fatal_cleanup();
+ }
+ if (buf[i] == '\r') {
+ buf[i] = '\n';
+ buf[i + 1] = 0;
+ continue;
+ }
+ if (buf[i] == '\n') {
+ /* buf[i] == '\n' */
+ buf[i + 1] = 0;
+ break;
+ }
+ }
+ buf[sizeof(buf) - 1] = 0;
+ client_version_string = xstrdup(buf);
}
- }
-
- /* 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;
+ /*
+ * Check that the versions match. In future this might accept
+ * several versions and set appropriate flags to handle them.
+ */
+ if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
+ &remote_major, &remote_minor, remote_version) != 3) {
+ s = "Protocol mismatch.\n";
+ (void) atomicio(write, sock_out, s, strlen(s));
+ close(sock_in);
+ close(sock_out);
+ log("Bad protocol version identification '%.100s' from %s",
+ client_version_string, get_remote_ipaddr());
+ fatal_cleanup();
}
- if (buf[i] == '\n')
- {
- /* buf[i] == '\n' */
- buf[i + 1] = 0;
- break;
+ debug("Client protocol version %d.%d; client software version %.100s",
+ remote_major, remote_minor, remote_version);
+
+ compat_datafellows(remote_version);
+
+ mismatch = 0;
+ switch(remote_major) {
+ case 1:
+ if (remote_minor == 99) {
+ if (options.protocol & SSH_PROTO_2)
+ enable_compat20();
+ else
+ mismatch = 1;
+ break;
+ }
+ if (!(options.protocol & SSH_PROTO_1)) {
+ mismatch = 1;
+ break;
+ }
+ if (remote_minor < 3) {
+ packet_disconnect("Your ssh version is too old and "
+ "is no longer supported. Please install a newer version.");
+ } else if (remote_minor == 3) {
+ /* note that this disables agent-forwarding */
+ enable_compat13();
+ }
+ break;
+ case 2:
+ if (options.protocol & SSH_PROTO_2) {
+ enable_compat20();
+ break;
+ }
+ /* FALLTHROUGH */
+ default:
+ mismatch = 1;
+ break;
}
- }
- 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_LIBPAM
- {
- int retval;
-
- if (pamh != NULL)
- {
- debug("Closing PAM session.");
- retval = pam_close_session((pam_handle_t *)pamh, 0);
-
- debug("Terminating PAM library.");
- if (pam_end((pam_handle_t *)pamh, retval) != PAM_SUCCESS)
- log("Cannot release PAM authentication.");
-
- fatal_remove_cleanup(&pam_cleanup_proc, NULL);
- }
- }
-#endif /* HAVE_LIBPAM */
-
- packet_close();
-
- exit(0);
+ chop(server_version_string);
+ chop(client_version_string);
+ debug("Local version string %.200s", server_version_string);
+
+ if (mismatch) {
+ 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: %.200s vs. %.200s",
+ get_remote_ipaddr(),
+ server_version_string, client_version_string);
+ fatal_cleanup();
+ }
+ if (compat20)
+ packet_set_ssh2_format();
}
-/* 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)
+void
+destroy_sensitive_data(void)
{
- int i, len;
- 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. */
- if (BN_num_bits(sensitive_data.private_key->n) <
- BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
- fatal("do_connection: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
- 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: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d",
- 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);
- len = BN_num_bytes(session_key_int);
- if (len <= 0 || len > sizeof(session_key))
- fatal("do_connection: bad len: session_key_int %d > sizeof(session_key) %d",
- len, sizeof(session_key));
- memset(session_key, 0, sizeof(session_key));
- BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
-
- /* 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);
+ /* Destroy the private and public keys. They will no longer be needed. */
+ if (public_key)
+ RSA_free(public_key);
+ if (sensitive_data.private_key)
+ RSA_free(sensitive_data.private_key);
+ if (sensitive_data.host_key)
+ RSA_free(sensitive_data.host_key);
+ if (sensitive_data.dsa_host_key != NULL)
+ key_free(sensitive_data.dsa_host_key);
}
-/* 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)
+/*
+ * returns 1 if connection should be dropped, 0 otherwise.
+ * dropping starts at connection #max_startups_begin with a probability
+ * of (max_startups_rate/100). the probability increases linearly until
+ * all connections are dropped for startups > max_startups
+ */
+int
+drop_connection(int startups)
{
- 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;
+ double p, r;
+
+ if (startups < options.max_startups_begin)
+ return 0;
+ if (startups >= options.max_startups)
+ return 1;
+ if (options.max_startups_rate == 100)
+ return 1;
+
+ p = 100 - options.max_startups_rate;
+ p *= startups - options.max_startups_begin;
+ p /= (double) (options.max_startups - options.max_startups_begin);
+ p += options.max_startups_rate;
+ p /= 100.0;
+ r = arc4random() / (double) UINT_MAX;
+
+ debug("drop_connection: p %g, r %g", p, r);
+ return (r < p) ? 1 : 0;
}
-/* 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
+int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
+int startup_pipe; /* in child */
-void
-do_authentication(char *user, int privileged_port)
+/*
+ * Main program for the daemon.
+ */
+int
+main(int ac, char **av)
{
- int type;
- int authenticated = 0;
- int authentication_failures = 0;
- char *password = NULL;
- struct passwd *pw, pwcopy;
- char *client_user = NULL;
- unsigned int client_host_key_bits;
- BIGNUM *client_host_key_e, *client_host_key_n;
-#ifdef HAVE_LIBPAM
- int pam_retval;
-#endif /* HAVE_LIBPAM */
-
-#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))
- eat_packets_and_disconnect(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);
- pw = &pwcopy;
-
-#ifdef HAVE_LIBPAM
- debug("Starting up PAM with username \"%.200s\"", pw->pw_name);
- pam_retval = pam_start("sshd", pw->pw_name, &conv, (pam_handle_t**)&pamh);
- if (pam_retval != PAM_SUCCESS)
- {
- log("PAM initialisation failed: %.200s", pam_strerror((pam_handle_t *)pamh, pam_retval));
- eat_packets_and_disconnect(user);
- }
- fatal_add_cleanup(&pam_cleanup_proc, NULL);
-#endif
+ extern char *optarg;
+ extern int optind;
+ int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
+ pid_t pid;
+ socklen_t fromlen;
+ int silent = 0;
+ fd_set *fdset;
+ struct sockaddr_storage from;
+ const char *remote_ip;
+ int remote_port;
+ FILE *f;
+ struct linger linger;
+ struct addrinfo *ai;
+ char ntop[NI_MAXHOST], strport[NI_MAXSERV];
+ int listen_sock, maxfd;
+ int startup_p[2];
+ int startups = 0;
+
+ init_rng();
+
+ /* Save argv[0]. */
+ saved_argc = ac;
+ 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:u: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':
+ if (0 == debug_flag) {
+ debug_flag = 1;
+ options.log_level = SYSLOG_LEVEL_DEBUG1;
+ } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
+ options.log_level++;
+ } else {
+ fprintf(stderr, "Too high debugging level.\n");
+ exit(1);
+ }
+ break;
+ case 'i':
+ inetd_flag = 1;
+ break;
+ case 'Q':
+ silent = 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) {
+ fprintf(stderr, "too many ports.\n");
+ exit(1);
+ }
+ 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 'u':
+ utmp_len = atoi(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)\n", SERVER_CONFIG_FILE);
+ fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\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, " -u len Maximum hostname length for utmp recording\n");
+ fprintf(stderr, " -4 Use IPv4 only\n");
+ fprintf(stderr, " -6 Use IPv6 only\n");
+ exit(1);
+ }
+ }
- /* 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.");
+ /*
+ * 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,
+ !silent && !inetd_flag);
+
+ /* Read server configuration options from the configuration file. */
+ read_server_config(&options, config_file_name);
+
+ /* Fill in default values for those options not explicitly set. */
+ fill_default_server_options(&options);
+
+ /* Check that there are no remaining arguments. */
+ if (optind < ac) {
+ fprintf(stderr, "Extra argument %s.\n", av[optind]);
+ exit(1);
+ }
- debug("Attempting authentication for %.100s.", user);
+ debug("sshd version %.100s", SSH_VERSION);
- /* 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)
- {
+ sensitive_data.dsa_host_key = NULL;
+ sensitive_data.host_key = NULL;
-#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(pw, 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;
-#ifndef HAVE_LIBPAM
- xfree(client_user);
-#endif /* HAVE_LIBPAM */
- break;
- }
- log("Rhosts authentication failed for %.100s, remote %.100s.",
- user, client_user);
-#ifndef HAVE_LIBPAM
- xfree(client_user);
-#endif /* HAVE_LIBPAM */
- 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;
-#ifndef HAVE_LIBPAM
- xfree(client_user);
-#endif /* HAVE_LIBPAM */
- 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);
-#ifndef HAVE_LIBPAM
- xfree(client_user);
-#endif /* HAVE_LIBPAM */
- 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);
- }
-
-#ifdef HAVE_LIBPAM
- pampasswd = password;
-
- pam_retval = pam_authenticate((pam_handle_t *)pamh, 0);
- if (pam_retval == PAM_SUCCESS)
- {
- log("PAM Password authentication accepted for \"%.100s\"", user);
- authenticated = 1;
- break;
- } else
- {
- log("PAM Password authentication for \"%.100s\" failed: %s",
- user, pam_strerror((pam_handle_t *)pamh, pam_retval));
- break;
- }
-#else /* HAVE_LIBPAM */
- /* 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;
-#endif /* HAVE_LIBPAM */
-
- case SSH_CMSG_AUTH_TIS:
- /* TIS Authentication is unsupported */
- log("TIS authentication disabled.");
- break;
+ /* check if RSA support exists */
+ if ((options.protocol & SSH_PROTO_1) &&
+ rsa_alive() == 0) {
+ log("no RSA support in libssl and libcrypto. See ssl(8)");
+ log("Disabling protocol version 1");
+ options.protocol &= ~SSH_PROTO_1;
+ }
+ /* Load the RSA/DSA host key. It must have empty passphrase. */
+ if (options.protocol & SSH_PROTO_1) {
+ Key k;
+ sensitive_data.host_key = RSA_new();
+ k.type = KEY_RSA;
+ k.rsa = sensitive_data.host_key;
+ errno = 0;
+ if (!load_private_key(options.host_key_file, "", &k, NULL)) {
+ error("Could not load host key: %.200s: %.100s",
+ options.host_key_file, strerror(errno));
+ log("Disabling protocol version 1");
+ options.protocol &= ~SSH_PROTO_1;
+ }
+ k.rsa = NULL;
+ }
+ if (options.protocol & SSH_PROTO_2) {
+ sensitive_data.dsa_host_key = key_new(KEY_DSA);
+ if (!load_private_key(options.host_dsa_key_file, "", sensitive_data.dsa_host_key, NULL)) {
- 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. */
+ error("Could not load DSA host key: %.200s", options.host_dsa_key_file);
+ log("Disabling protocol version 2");
+ options.protocol &= ~SSH_PROTO_2;
+ }
+ }
+ if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) {
+ if (silent == 0)
+ fprintf(stderr, "sshd: no hostkeys available -- exiting.\n");
+ log("sshd: no hostkeys available -- exiting.\n");
+ exit(1);
}
- /* If successfully authenticated, break out of loop. */
- if (authenticated)
- break;
-
- if (++authentication_failures >= MAX_AUTH_FAILURES) {
- packet_disconnect("Too many authentication failures for %.100s from %.200s",
- pw->pw_name, get_canonical_hostname());
- }
-
- /* Send a message indicating that the authentication attempt failed. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
- }
-
- /* 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 HAVE_LIBPAM
- do_pam_account_and_session(pw->pw_name, password, client_user, get_canonical_hostname());
-
- /* Clean up */
- if (client_user != NULL)
- xfree(client_user);
-
- if (password != NULL)
- {
- memset(password, 0, strlen(password));
- xfree(password);
- }
-#endif /* HAVE_LIBPAM */
-
- /* The user has been authenticated and accepted. */
- packet_start(SSH_SMSG_SUCCESS);
- packet_send();
- packet_write_wait();
-
- /* Perform session preparation. */
- do_authenticated(pw);
-}
-/* Read authentication messages, but return only failures until */
-/* max auth attempts exceeded, then disconnect */
-void eat_packets_and_disconnect(const char *user)
-{
- int authentication_failures = 0;
-
- 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. */
- while(1)
- {
- /* Read a packet. This will not return if the client disconnects. */
- int plen;
-#ifndef SKEY
- (void) packet_read(&plen);
-#else /* SKEY */
- int type = packet_read(&plen);
- 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 /* SKEY */
- if (++authentication_failures >= MAX_AUTH_FAILURES)
- {
- packet_disconnect("Too many authentication failures for %.100s from %.200s",
- user, get_canonical_hostname());
- }
- /* Send failure. This should be indistinguishable from a failed
- authentication. */
- packet_start(SSH_SMSG_FAILURE);
- packet_send();
- packet_write_wait();
- }
- /*NOTREACHED*/
- abort();
-}
+ /* Check certain values for sanity. */
+ if (options.protocol & SSH_PROTO_1) {
+ if (options.server_key_bits < 512 ||
+ options.server_key_bits > 32768) {
+ fprintf(stderr, "Bad server key size.\n");
+ exit(1);
+ }
+ /*
+ * Check that server and host key lengths differ sufficiently. This
+ * is necessary to make double encryption work with rsaref. Oh, I
+ * hate software patents. I dont know if this can go? Niels
+ */
+ if (options.server_key_bits >
+ BN_num_bits(sensitive_data.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);
+ }
+ }
-/* Remove local Xauthority file. */
-static void
-xauthfile_cleanup_proc(void *ignore)
-{
- debug("xauthfile_cleanup_proc called");
+#ifdef HAVE_SCO_PROTECTED_PW
+ (void) set_auth_parameters(ac, av);
+#endif
- if (xauthfile != NULL) {
- unlink(xauthfile);
- xfree(xauthfile);
- xauthfile = NULL;
- }
-}
+ /* 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));
-/* 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. */
+ /* 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);
+
+ /* 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);
+ startup_pipe = -1;
+ /*
+ * We intentionally do not close the descriptors 0, 1, and 2
+ * as our code for setting the descriptors won\'t work if
+ * ttyfd happens to be one of those.
+ */
+ debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
+
+ if (options.protocol & SSH_PROTO_1) {
+ 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) &&
+ (!ai->ai_next)) {
+ error("Bind to port %s on %s failed: %.200s.",
+ strport, ntop, strerror(errno));
+ close(listen_sock);
+ continue;
+ }
+ listen_socks[num_listen_socks] = listen_sock;
+ num_listen_socks++;
+
+ /* Start listening on the port. */
+ log("Server listening on %s port %s.", ntop, strport);
+ if (listen(listen_sock, 5) < 0)
+ fatal("listen: %.100s", strerror(errno));
-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);
- fatal_add_cleanup(xauthfile_cleanup_proc, NULL);
- }
- 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;
+ }
+ 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(options.pid_file, "wb");
+ if (f) {
+ fprintf(f, "%u\n", (unsigned int) getpid());
+ fclose(f);
+ }
+ }
+ if (options.protocol & SSH_PROTO_1) {
+ 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);
+ }
- 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;
+ /* 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 */
+ fdset = NULL;
+ maxfd = 0;
+ for (i = 0; i < num_listen_socks; i++)
+ if (listen_socks[i] > maxfd)
+ maxfd = listen_socks[i];
+ /* pipes connected to unauthenticated childs */
+ startup_pipes = xmalloc(options.max_startups * sizeof(int));
+ for (i = 0; i < options.max_startups; i++)
+ startup_pipes[i] = -1;
+
+ /*
+ * Stay listening for connections until the system crashes or
+ * the daemon is killed with a signal.
+ */
+ for (;;) {
+ if (received_sighup)
+ sighup_restart();
+ if (fdset != NULL)
+ xfree(fdset);
+ fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
+ fdset = (fd_set *)xmalloc(fdsetsz);
+ memset(fdset, 0, fdsetsz);
+
+ for (i = 0; i < num_listen_socks; i++)
+ FD_SET(listen_socks[i], fdset);
+ for (i = 0; i < options.max_startups; i++)
+ if (startup_pipes[i] != -1)
+ FD_SET(startup_pipes[i], fdset);
+
+ /* Wait in select until there is a connection. */
+ if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) {
+ if (errno != EINTR)
+ error("select: %.100s", strerror(errno));
+ continue;
+ }
+ for (i = 0; i < options.max_startups; i++)
+ if (startup_pipes[i] != -1 &&
+ FD_ISSET(startup_pipes[i], fdset)) {
+ /*
+ * the read end of the pipe is ready
+ * if the child has closed the pipe
+ * after successfull authentication
+ * or if the child has died
+ */
+ close(startup_pipes[i]);
+ startup_pipes[i] = -1;
+ startups--;
+ }
+ for (i = 0; i < num_listen_socks; i++) {
+ if (!FD_ISSET(listen_socks[i], fdset))
+ continue;
+ fromlen = sizeof(from);
+ newsock = accept(listen_socks[i], (struct sockaddr *)&from,
+ &fromlen);
+ if (newsock < 0) {
+ if (errno != EINTR && errno != EWOULDBLOCK)
+ error("accept: %.100s", strerror(errno));
+ continue;
+ }
+ if (fcntl(newsock, F_SETFL, 0) < 0) {
+ error("newsock del O_NONBLOCK: %s", strerror(errno));
+ continue;
+ }
+ if (drop_connection(startups) == 1) {
+ debug("drop connection #%d", startups);
+ close(newsock);
+ continue;
+ }
+ if (pipe(startup_p) == -1) {
+ close(newsock);
+ continue;
+ }
+
+ for (j = 0; j < options.max_startups; j++)
+ if (startup_pipes[j] == -1) {
+ startup_pipes[j] = startup_p[0];
+ if (maxfd < startup_p[0])
+ maxfd = startup_p[0];
+ startups++;
+ break;
+ }
+
+ /*
+ * Got connection. Fork a child to handle it, unless
+ * we are in debugging mode.
+ */
+ if (debug_flag) {
+ /*
+ * In debugging mode. Close the listening
+ * socket, and start processing the
+ * connection without forking.
+ */
+ debug("Server will not fork when running in debugging mode.");
+ close_listen_socks();
+ sock_in = newsock;
+ sock_out = newsock;
+ startup_pipe = -1;
+ pid = getpid();
+ break;
+ } else {
+ /*
+ * Normal production daemon. Fork, and have
+ * the child process the connection. The
+ * parent continues listening.
+ */
+ if ((pid = fork()) == 0) {
+ /*
+ * Child. Close the listening and max_startup
+ * sockets. Start using the accepted socket.
+ * Reinitialize logging (since our pid has
+ * changed). We break out of the loop to handle
+ * the connection.
+ */
+ startup_pipe = startup_p[1];
+ for (j = 0; j < options.max_startups; j++)
+ if (startup_pipes[j] != -1)
+ close(startup_pipes[j]);
+ 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);
+
+ close(startup_p[1]);
+
+ /* 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);
+ }
+ /* child process check (or debug mode) */
+ if (num_listen_socks < 0)
+ break;
+ }
}
- /* 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)
+ /* 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);
+ signal(SIGINT, SIG_DFL);
+
+ /*
+ * Set socket options for the connection. We want the socket to
+ * close as fast as possible without waiting for anything. If the
+ * connection is not a socket, these will do nothing.
+ */
+ /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
+ linger.l_onoff = 1;
+ linger.l_linger = 5;
+ setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (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
+ /* XXX LIBWRAP noes not know about IPv6 */
{
- enable_compression_after_reply = 0;
- packet_start_compression(compression_level);
- }
+ struct request_info req;
- 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;
- }
-}
+ request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL);
+ fromhost(&req);
-/* 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 */
-}
+ if (!hosts_access(&req)) {
+ close(sock_in);
+ close(sock_out);
+ refuse(&req);
+ }
+/*XXX IPv6 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);
+
+ sshd_exchange_identification(sock_in, sock_out);
+ /*
+ * 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.kerberos_authentication) {
+ debug("Kerberos Authentication disabled, only available for IPv4.");
+ options.kerberos_authentication = 0;
+ }
+#endif /* KRB4 */
-struct pty_cleanup_context
-{
- const char *ttyname;
- int pid;
-};
+ packet_set_nonblocking();
-/* Function to perform cleanup if we get aborted abnormally (e.g., due to a
- dropped connection). */
+ /* perform the key exchange */
+ /* authenticate user and start session */
+ if (compat20) {
+ do_ssh2_kex();
+ do_authentication2();
+ } else {
+ do_ssh1_kex();
+ do_authentication();
+ }
-void pty_cleanup_proc(void *context)
-{
- struct pty_cleanup_context *cu = context;
+#ifdef KRB4
+ /* Cleanup user's ticket cache file. */
+ if (options.kerberos_ticket_cleanup)
+ (void) dest_tkt();
+#endif /* KRB4 */
- debug("pty_cleanup_proc called");
+ /* The connection has been terminated. */
+ verbose("Closing connection to %.100s", remote_ip);
- /* Record that the user has logged out. */
- record_logout(cu->pid, cu->ttyname);
+#ifdef USE_PAM
+ finish_pam();
+#endif /* USE_PAM */
- /* Release the pseudo-tty. */
- pty_release(cu->ttyname);
+ packet_close();
+ exit(0);
}
-/* 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)
+/*
+ * SSH1 key exchange
+ */
+void
+do_ssh1_kex()
{
- 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, 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)
- fatal("getpeername: %.100s", strerror(errno));
+ 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;
}
- /* 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;
-
-#ifdef HAVE_LIBPAM
- /* output the results of the pamconv() */
- if (!quiet_login && pamconv_msg != NULL)
- fprintf(stderr, pamconv_msg);
+ /*
+ * 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_mask1());
+
+ /* 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
-
- /* 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 *));
+#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
+#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);
}
- /* 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);
+ 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. */
+ destroy_sensitive_data();
+
+ /*
+ * 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();
}
-/* 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)
+/*
+ * SSH2 key exchange: diffie-hellman-group1-sha1
+ */
+void
+do_ssh2_kex()
{
- 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;
+ Buffer *server_kexinit;
+ Buffer *client_kexinit;
+ int payload_len, dlen;
+ int slen;
+ unsigned int klen, kout;
+ unsigned char *signature = NULL;
+ unsigned char *server_host_key_blob = NULL;
+ unsigned int sbloblen;
+ DH *dh;
+ BIGNUM *dh_client_pub = 0;
+ BIGNUM *shared_secret = 0;
+ int i;
+ unsigned char *kbuf;
+ unsigned char *hash;
+ Kex *kex;
+ char *cprop[PROPOSAL_MAX];
+
+/* KEXINIT */
+
+ if (options.ciphers != NULL) {
+ myproposal[PROPOSAL_ENC_ALGS_CTOS] =
+ myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
}
-
- /* 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];
-
-#ifndef HAVE_LIBPAM /* pam_nologin handles this */
- /* 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);
- }
+ server_kexinit = kex_init(myproposal);
+ client_kexinit = xmalloc(sizeof(*client_kexinit));
+ buffer_init(client_kexinit);
+
+ /* algorithm negotiation */
+ kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
+ kex = kex_choose_conf(cprop, myproposal, 1);
+ for (i = 0; i < PROPOSAL_MAX; i++)
+ xfree(cprop[i]);
+
+/* KEXDH */
+
+ debug("Wait SSH2_MSG_KEXDH_INIT.");
+ packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
+
+ /* key, cert */
+ dh_client_pub = BN_new();
+ if (dh_client_pub == NULL)
+ fatal("dh_client_pub == NULL");
+ packet_get_bignum2(dh_client_pub, &dlen);
+
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "\ndh_client_pub= ");
+ BN_print_fp(stderr, dh_client_pub);
+ fprintf(stderr, "\n");
+ debug("bits %d", BN_num_bits(dh_client_pub));
#endif
- /* 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
- {
- extern char *ticket;
-
- if (ticket)
- child_set_env(&env, &envsize, "KRBTKFILE", ticket);
- }
-#endif /* KRB4 */
-
-#ifdef HAVE_LIBPAM
- /* Pull in any environment variables that may have been set by PAM. */
- {
- char *equal_sign, var_name[256], var_val[256];
- long this_var;
- char **pam_env = pam_getenvlist((pam_handle_t *)pamh);
- for(this_var = 0; pam_env && pam_env[this_var]; this_var++)
- {
- if(strlen(pam_env[this_var]) < (sizeof(var_name) - 1))
- if((equal_sign = strstr(pam_env[this_var], "=")) != NULL)
- {
- memset(var_name, 0, sizeof(var_name));
- memset(var_val, 0, sizeof(var_val));
- strncpy(var_name, pam_env[this_var],
- equal_sign - pam_env[this_var]);
- strcpy(var_val, equal_sign + 1);
- child_set_env(&env, &envsize, var_name, var_val);
- }
- }
- }
-#endif /* HAVE_LIBPAM */
-
- /* 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(LOGIN_PROGRAM, "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);
+ /* generate DH key */
+ dh = dh_new_group1(); /* XXX depends on 'kex' */
+
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "\np= ");
+ BN_print_fp(stderr, dh->p);
+ fprintf(stderr, "\ng= ");
+ bn_print(dh->g);
+ fprintf(stderr, "\npub= ");
+ BN_print_fp(stderr, dh->pub_key);
+ fprintf(stderr, "\n");
+ DHparams_print_fp(stderr, dh);
+#endif
+ if (!dh_pub_is_valid(dh, dh_client_pub))
+ packet_disconnect("bad client public DH value");
+
+ klen = DH_size(dh);
+ kbuf = xmalloc(klen);
+ kout = DH_compute_key(kbuf, dh_client_pub, dh);
+
+#ifdef DEBUG_KEXDH
+ debug("shared secret: len %d/%d", klen, kout);
+ fprintf(stderr, "shared secret == ");
+ for (i = 0; i< kout; i++)
+ fprintf(stderr, "%02x", (kbuf[i])&0xff);
+ fprintf(stderr, "\n");
+#endif
+ shared_secret = BN_new();
+
+ BN_bin2bn(kbuf, kout, shared_secret);
+ memset(kbuf, 0, klen);
+ xfree(kbuf);
+
+ /* XXX precompute? */
+ dsa_make_key_blob(sensitive_data.dsa_host_key, &server_host_key_blob, &sbloblen);
+
+ /* calc H */ /* XXX depends on 'kex' */
+ hash = kex_hash(
+ client_version_string,
+ server_version_string,
+ buffer_ptr(client_kexinit), buffer_len(client_kexinit),
+ buffer_ptr(server_kexinit), buffer_len(server_kexinit),
+ (char *)server_host_key_blob, sbloblen,
+ dh_client_pub,
+ dh->pub_key,
+ shared_secret
+ );
+ buffer_free(client_kexinit);
+ buffer_free(server_kexinit);
+ xfree(client_kexinit);
+ xfree(server_kexinit);
+#ifdef DEBUG_KEXDH
+ fprintf(stderr, "hash == ");
+ for (i = 0; i< 20; i++)
+ fprintf(stderr, "%02x", (hash[i])&0xff);
+ fprintf(stderr, "\n");
+#endif
+ /* save session id := H */
+ /* XXX hashlen depends on KEX */
+ session_id2_len = 20;
+ session_id2 = xmalloc(session_id2_len);
+ memcpy(session_id2, hash, session_id2_len);
+
+ /* sign H */
+ /* XXX hashlen depends on KEX */
+ dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20);
+
+ destroy_sensitive_data();
+
+ /* send server hostkey, DH pubkey 'f' and singed H */
+ packet_start(SSH2_MSG_KEXDH_REPLY);
+ packet_put_string((char *)server_host_key_blob, sbloblen);
+ packet_put_bignum2(dh->pub_key); /* f */
+ packet_put_string((char *)signature, slen);
+ packet_send();
+ xfree(signature);
+ xfree(server_host_key_blob);
+ packet_write_wait();
+
+ kex_derive_keys(kex, hash, shared_secret);
+ packet_set_kex(kex);
+
+ /* have keys, free DH */
+ DH_free(dh);
+
+ debug("send SSH2_MSG_NEWKEYS.");
+ packet_start(SSH2_MSG_NEWKEYS);
+ packet_send();
+ packet_write_wait();
+ debug("done: send SSH2_MSG_NEWKEYS.");
+
+ debug("Wait SSH2_MSG_NEWKEYS.");
+ packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
+ debug("GOT SSH2_MSG_NEWKEYS.");
+
+#ifdef DEBUG_KEXDH
+ /* send 1st encrypted/maced/compressed message */
+ packet_start(SSH2_MSG_IGNORE);
+ packet_put_cstring("markus");
+ packet_send();
+ packet_write_wait();
+#endif
+ debug("done: KEX2.");
}
andersk / openssh.git / blobdiff