* 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
+ * 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.
+ * connection. This can also handle forwarding of X11, TCP/IP, and
+ * authentication agent connections.
*
- * SSH2 implementation,
- * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ * 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("$OpenBSD: sshd.c,v 1.123 2000/07/18 01:25:01 djm Exp $");
+RCSID("$OpenBSD: sshd.c,v 1.132 2000/10/13 18:34:46 markus Exp $");
#include "xmalloc.h"
#include "rsa.h"
#include "ssh.h"
#include "pty.h"
#include "packet.h"
-#include "cipher.h"
#include "mpaux.h"
#include "servconf.h"
#include "uidswap.h"
#include <openssl/rsa.h>
#include "key.h"
#include "dsa.h"
+#include "dh.h"
#include "auth.h"
#include "myproposal.h"
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_ssh1_kex();
void do_ssh2_kex();
+void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
+void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
+
/*
* Close all listening sockets
*/
if (buf[i] == '\r') {
buf[i] = '\n';
buf[i + 1] = 0;
+ /* Kludge for F-Secure Macintosh < 1.0.2 */
+ if (i == 12 &&
+ strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
+ break;
continue;
}
if (buf[i] == '\n') {
key_free(sensitive_data.dsa_host_key);
}
+/*
+ * 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)
+{
+ 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;
+}
+
int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
int startup_pipe; /* in child */
initialize_server_options(&options);
/* Parse command-line arguments. */
- while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ46")) != EOF) {
+ while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:diqQ46")) != EOF) {
switch (opt) {
case '4':
IPv4or6 = AF_INET;
config_file_name = optarg;
break;
case 'd':
- debug_flag = 1;
- options.log_level = SYSLOG_LEVEL_DEBUG;
+ 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 'p':
options.ports_from_cmdline = 1;
- if (options.num_ports >= MAX_PORTS)
- fatal("too many ports.\n");
+ if (options.num_ports >= MAX_PORTS) {
+ fprintf(stderr, "too many ports.\n");
+ exit(1);
+ }
options.ports[options.num_ports++] = atoi(optarg);
break;
case 'g':
/* 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\n");
+ 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, " -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);
}
}
+#ifdef HAVE_SCO_PROTECTED_PW
+ (void) set_auth_parameters(ac, av);
+#endif
+
/* Initialize the log (it is reinitialized below in case we forked). */
if (debug_flag && !inetd_flag)
log_stderr = 1;
* fail if there already is a daemon, and this will
* overwrite any old pid in the file.
*/
- f = fopen(options.pid_file, "w");
+ f = fopen(options.pid_file, "wb");
if (f) {
fprintf(f, "%u\n", (unsigned int) getpid());
fclose(f);
error("newsock del O_NONBLOCK: %s", strerror(errno));
continue;
}
- if (startups >= options.max_startups) {
+ if (drop_connection(startups) == 1) {
+ debug("drop connection #%d", startups);
close(newsock);
continue;
}
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
packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
/* Declare which ciphers we support. */
- packet_put_int(cipher_mask1());
+ packet_put_int(cipher_mask_ssh1(0));
/* Declare supported authentication types. */
auth_mask = 0;
/* Get cipher type and check whether we accept this. */
cipher_type = packet_get_char();
- if (!(cipher_mask() & (1 << cipher_type)))
+ if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
packet_disconnect("Warning: client selects unsupported cipher.");
/* Get check bytes from the packet. These must match those we
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));
+ len, (int) sizeof(session_key));
memset(session_key, 0, sizeof(session_key));
BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
{
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 payload_len;
int i;
- unsigned char *kbuf;
- unsigned char *hash;
Kex *kex;
char *cprop[PROPOSAL_MAX];
for (i = 0; i < PROPOSAL_MAX; i++)
xfree(cprop[i]);
-/* KEXDH */
+ switch (kex->kex_type) {
+ case DH_GRP1_SHA1:
+ ssh_dh1_server(kex, client_kexinit, server_kexinit);
+ break;
+ case DH_GEX_SHA1:
+ ssh_dhgex_server(kex, client_kexinit, server_kexinit);
+ break;
+ default:
+ fatal("Unsupported key exchange %d", kex->kex_type);
+ }
+
+ 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.");
+}
+
+/*
+ * SSH2 key exchange
+ */
+
+/* diffie-hellman-group1-sha1 */
+
+void
+ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
+{
+#ifdef DEBUG_KEXDH
+ int i;
+#endif
+ int payload_len, dlen;
+ int slen;
+ unsigned char *signature = NULL;
+ unsigned char *server_host_key_blob = NULL;
+ unsigned int sbloblen;
+ unsigned int klen, kout;
+ unsigned char *kbuf;
+ unsigned char *hash;
+ BIGNUM *shared_secret = 0;
+ DH *dh;
+ BIGNUM *dh_client_pub = 0;
+/* KEXDH */
debug("Wait SSH2_MSG_KEXDH_INIT.");
packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
#ifdef DEBUG_KEXDH
fprintf(stderr, "\ndh_client_pub= ");
- bignum_print(dh_client_pub);
+ BN_print_fp(stderr, dh_client_pub);
fprintf(stderr, "\n");
debug("bits %d", BN_num_bits(dh_client_pub));
#endif
#ifdef DEBUG_KEXDH
fprintf(stderr, "\np= ");
- bignum_print(dh->p);
+ BN_print_fp(stderr, dh->p);
fprintf(stderr, "\ng= ");
- bignum_print(dh->g);
+ bn_print(dh->g);
fprintf(stderr, "\npub= ");
- bignum_print(dh->pub_key);
+ 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");
xfree(kbuf);
/* XXX precompute? */
- dsa_make_key_blob(sensitive_data.dsa_host_key, &server_host_key_blob, &sbloblen);
+ dsa_make_key_blob(sensitive_data.dsa_host_key,
+ &server_host_key_blob, &sbloblen);
/* calc H */ /* XXX depends on 'kex' */
hash = kex_hash(
/* have keys, free DH */
DH_free(dh);
+}
- debug("send SSH2_MSG_NEWKEYS.");
- packet_start(SSH2_MSG_NEWKEYS);
+/* diffie-hellman-group-exchange-sha1 */
+
+void
+ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
+{
+#ifdef DEBUG_KEXDH
+ int i;
+#endif
+ int payload_len, dlen;
+ int slen, nbits;
+ unsigned char *signature = NULL;
+ unsigned char *server_host_key_blob = NULL;
+ unsigned int sbloblen;
+ unsigned int klen, kout;
+ unsigned char *kbuf;
+ unsigned char *hash;
+ BIGNUM *shared_secret = 0;
+ DH *dh;
+ BIGNUM *dh_client_pub = 0;
+
+/* KEXDHGEX */
+ debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
+ packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
+ nbits = packet_get_int();
+ dh = choose_dh(nbits);
+
+ debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
+ packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
+ packet_put_bignum2(dh->p);
+ packet_put_bignum2(dh->g);
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.");
+ debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
+ packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_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
- /* send 1st encrypted/maced/compressed message */
- packet_start(SSH2_MSG_IGNORE);
- packet_put_cstring("markus");
+ 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
+
+#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_gex(
+ 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,
+ nbits, dh->p, dh->g,
+ 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_KEX_DH_GEX_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();
-#endif
- debug("done: KEX2.");
+
+ kex_derive_keys(kex, hash, shared_secret);
+ packet_set_kex(kex);
+
+ /* have keys, free DH */
+ DH_free(dh);
}
+