- (djm) Big OpenBSD sync:

   - markus@cvs.openbsd.org  2000/09/30 10:27:44
     [log.c]
     allow loglevel debug
   - markus@cvs.openbsd.org  2000/10/03 11:59:57
     [packet.c]
     hmac->mac
   - markus@cvs.openbsd.org  2000/10/03 12:03:03
     [auth-krb4.c auth-passwd.c auth-rh-rsa.c auth-rhosts.c auth-rsa.c auth1.c]
     move fake-auth from auth1.c to individual auth methods, disables s/key in
     debug-msg
   - markus@cvs.openbsd.org  2000/10/03 12:16:48
     ssh.c
     do not resolve canonname, i have no idea why this was added oin ossh
   - markus@cvs.openbsd.org  2000/10/09 15:30:44
     ssh-keygen.1 ssh-keygen.c
     -X now reads private ssh.com DSA keys, too.
   - markus@cvs.openbsd.org  2000/10/09 15:32:34
     auth-options.c
     clear options on every call.
   - markus@cvs.openbsd.org  2000/10/09 15:51:00
     authfd.c authfd.h
     interop with ssh-agent2, from <res@shore.net>
   - markus@cvs.openbsd.org  2000/10/10 14:20:45
     compat.c
     use rexexp for version string matching
   - provos@cvs.openbsd.org  2000/10/10 22:02:18
     [kex.c kex.h myproposal.h ssh.h ssh2.h sshconnect2.c sshd.c dh.c dh.h]
     First rough implementation of the diffie-hellman group exchange.  The
     client can ask the server for bigger groups to perform the diffie-hellman
     in, thus increasing the attack complexity when using ciphers with longer
     keys.  University of Windsor provided network, T the company.
   - markus@cvs.openbsd.org  2000/10/11 13:59:52
     [auth-rsa.c auth2.c]
     clear auth options unless auth sucessfull
   - markus@cvs.openbsd.org  2000/10/11 14:00:27
     [auth-options.h]
     clear auth options unless auth sucessfull
   - markus@cvs.openbsd.org  2000/10/11 14:03:27
     [scp.1 scp.c]
     support 'scp -o' with help from mouring@pconline.com
   - markus@cvs.openbsd.org  2000/10/11 14:11:35
     [dh.c]
     Wall
   - markus@cvs.openbsd.org  2000/10/11 14:14:40
     [auth.h auth2.c readconf.c readconf.h readpass.c servconf.c servconf.h]
     [ssh.h sshconnect2.c sshd_config auth2-skey.c cli.c cli.h]
     add support for s/key (kbd-interactive) to ssh2, based on work by
     mkiernan@avantgo.com and me
   - markus@cvs.openbsd.org  2000/10/11 14:27:24
     [auth.c auth1.c auth2.c authfile.c cipher.c cipher.h kex.c kex.h]
     [myproposal.h packet.c readconf.c session.c ssh.c ssh.h sshconnect1.c]
     [sshconnect2.c sshd.c]
     new cipher framework
   - markus@cvs.openbsd.org  2000/10/11 14:45:21
     [cipher.c]
     remove DES
   - markus@cvs.openbsd.org  2000/10/12 03:59:20
     [cipher.c cipher.h sshconnect1.c sshconnect2.c sshd.c]
     enable DES in SSH-1 clients only
   - markus@cvs.openbsd.org  2000/10/12 08:21:13
     [kex.h packet.c]
     remove unused
   - markus@cvs.openbsd.org  2000/10/13 12:34:46
     [sshd.c]
     Kludge for F-Secure Macintosh < 1.0.2; appro@fy.chalmers.se
   - markus@cvs.openbsd.org  2000/10/13 12:59:15
     [cipher.c cipher.h myproposal.h  rijndael.c rijndael.h]
     rijndael/aes support
   - markus@cvs.openbsd.org  2000/10/13 13:10:54
     [sshd.8]
     more info about -V
   - markus@cvs.openbsd.org  2000/10/13 13:12:02
     [myproposal.h]
     prefer no compression

1 files changed, 197 insertions, 28 deletions

diff --git a/sshd.c b/sshd.c
index ae22cd953..e5c2508a1 100644
--- a/sshd.c
+++ b/sshd.c
@@ -40,14 +40,13 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: sshd.c,v 1.128 2000/09/17 15:38:59 markus 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"
@@ -63,6 +62,7 @@ RCSID("$OpenBSD: sshd.c,v 1.128 2000/09/17 15:38:59 markus Exp $");
 #include <openssl/rsa.h>
 #include "key.h"
 #include "dsa.h"
+#include "dh.h"
 
 #include "auth.h"
 #include "myproposal.h"
@@ -172,6 +172,9 @@ unsigned int utmp_len = MAXHOSTNAMELEN;
 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
  */
@@ -333,6 +336,10 @@ sshd_exchange_identification(int sock_in, int sock_out)
                         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') {
@@ -1151,7 +1158,7 @@ do_ssh1_kex()
         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;
@@ -1192,7 +1199,7 @@ do_ssh1_kex()
         /* 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
@@ -1296,18 +1303,8 @@ do_ssh2_kex()
 {
         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];
 
@@ -1327,8 +1324,63 @@ do_ssh2_kex()
         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);
 
@@ -1379,7 +1431,8 @@ do_ssh2_kex()
         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(
@@ -1429,23 +1482,139 @@ do_ssh2_kex()
 
         /* 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);
 }
+