1 /* 2 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 /* 25 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 26 * Use is subject to license terms. 27 */ 28 29 #pragma ident "%Z%%M% %I% %E% SMI" 30 31 #include "includes.h" 32 33 #ifdef GSSAPI 34 35 #include <openssl/crypto.h> 36 #include <openssl/bn.h> 37 38 #include "xmalloc.h" 39 #include "buffer.h" 40 #include "bufaux.h" 41 #include "compat.h" 42 #include "kex.h" 43 #include "log.h" 44 #include "packet.h" 45 #include "dh.h" 46 #include "ssh2.h" 47 #include "ssh-gss.h" 48 #include "monitor_wrap.h" 49 #include "auth.h" 50 51 Gssctxt *xxx_gssctxt; 52 extern Authctxt *x_authctxt; 53 54 static void kex_gss_send_error(Gssctxt *ctxt); 55 56 void 57 kexgss_server(Kex *kex) 58 { 59 OM_uint32 maj_status, min_status; 60 gss_buffer_desc gssbuf, send_tok, recv_tok, msg_tok; 61 Gssctxt *ctxt = NULL; 62 unsigned int klen, kout; 63 unsigned int sbloblen = 0; 64 unsigned char *kbuf, *hash; 65 unsigned char *server_host_key_blob = NULL; 66 DH *dh; 67 Key *server_host_key = NULL; 68 BIGNUM *shared_secret = NULL; 69 BIGNUM *dh_client_pub = NULL; 70 int type =0; 71 u_int slen; 72 gss_OID oid; 73 74 /* 75 * Load host key to advertise in a SSH_MSG_KEXGSS_HOSTKEY packet 76 * -- unlike KEX_DH/KEX_GEX no host key, no problem since it's 77 * the GSS-API that provides for server host authentication. 78 */ 79 if (kex->load_host_key != NULL && 80 !(datafellows & SSH_BUG_GSSKEX_HOSTKEY)) 81 server_host_key = kex->load_host_key(kex->hostkey_type); 82 if (server_host_key != NULL) 83 key_to_blob(server_host_key, &server_host_key_blob, &sbloblen); 84 85 86 /* Initialise GSSAPI */ 87 88 ssh_gssapi_oid_of_kexname(kex->name, &oid); 89 if (oid == GSS_C_NULL_OID) { 90 fatal("Couldn't match the negotiated GSS key exchange"); 91 } 92 93 ssh_gssapi_build_ctx(&xxx_gssctxt, 0, oid); 94 95 ctxt = xxx_gssctxt; 96 97 do { 98 debug("Wait SSH2_MSG_GSSAPI_INIT"); 99 type = packet_read(); 100 switch(type) { 101 case SSH2_MSG_KEXGSS_INIT: 102 if (dh_client_pub!=NULL) 103 fatal("Received KEXGSS_INIT after initialising"); 104 recv_tok.value=packet_get_string(&slen); 105 recv_tok.length=slen; /* int vs. size_t */ 106 107 dh_client_pub = BN_new(); 108 109 if (dh_client_pub == NULL) 110 fatal("dh_client_pub == NULL"); 111 packet_get_bignum2(dh_client_pub); 112 113 /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ 114 if (sbloblen) { 115 packet_start(SSH2_MSG_KEXGSS_HOSTKEY); 116 packet_put_string(server_host_key_blob, sbloblen); 117 packet_send(); 118 packet_write_wait(); 119 } 120 break; 121 case SSH2_MSG_KEXGSS_CONTINUE: 122 recv_tok.value=packet_get_string(&slen); 123 recv_tok.length=slen; /* int vs. size_t */ 124 break; 125 default: 126 packet_disconnect("Protocol error: didn't expect packet type %d", 127 type); 128 } 129 130 maj_status=PRIVSEP(ssh_gssapi_accept_ctx(ctxt,&recv_tok, 131 &send_tok)); 132 133 xfree(recv_tok.value); /* We allocated this, not gss */ 134 135 if (dh_client_pub == NULL) 136 fatal("No client public key"); 137 138 if (maj_status == GSS_S_CONTINUE_NEEDED) { 139 debug("Sending GSSAPI_CONTINUE"); 140 packet_start(SSH2_MSG_KEXGSS_CONTINUE); 141 packet_put_string(send_tok.value,send_tok.length); 142 packet_send(); 143 packet_write_wait(); 144 (void) gss_release_buffer(&min_status, &send_tok); 145 } 146 } while (maj_status == GSS_S_CONTINUE_NEEDED); 147 148 if (GSS_ERROR(maj_status)) { 149 kex_gss_send_error(ctxt); 150 if (send_tok.length>0) { 151 packet_start(SSH2_MSG_KEXGSS_CONTINUE); 152 packet_put_string(send_tok.value,send_tok.length); 153 packet_send(); 154 packet_write_wait(); 155 (void) gss_release_buffer(&min_status, &send_tok); 156 } 157 fatal("accept_ctx died"); 158 } 159 160 debug("gss_complete"); 161 if (!(ctxt->flags & GSS_C_MUTUAL_FLAG)) 162 fatal("Mutual authentication flag wasn't set"); 163 164 if (!(ctxt->flags & GSS_C_INTEG_FLAG)) 165 fatal("Integrity flag wasn't set"); 166 167 dh = dh_new_group1(); 168 dh_gen_key(dh, kex->we_need * 8); 169 170 if (!dh_pub_is_valid(dh, dh_client_pub)) 171 packet_disconnect("bad client public DH value"); 172 173 klen = DH_size(dh); 174 kbuf = xmalloc(klen); 175 kout = DH_compute_key(kbuf, dh_client_pub, dh); 176 177 shared_secret = BN_new(); 178 BN_bin2bn(kbuf, kout, shared_secret); 179 (void) memset(kbuf, 0, klen); 180 xfree(kbuf); 181 182 /* The GSSAPI hash is identical to the Diffie Helman one */ 183 hash = kex_dh_hash( 184 kex->client_version_string, 185 kex->server_version_string, 186 buffer_ptr(&kex->peer), buffer_len(&kex->peer), 187 buffer_ptr(&kex->my), buffer_len(&kex->my), 188 server_host_key_blob, sbloblen, 189 dh_client_pub, 190 dh->pub_key, 191 shared_secret 192 ); 193 BN_free(dh_client_pub); 194 195 if (kex->session_id == NULL) { 196 kex->session_id_len = 20; 197 kex->session_id = xmalloc(kex->session_id_len); 198 (void) memcpy(kex->session_id, hash, kex->session_id_len); 199 } else if (x_authctxt != NULL && x_authctxt->success) { 200 ssh_gssapi_storecreds(ctxt, x_authctxt); 201 } 202 203 /* Should fix kex_dh_hash to output hash length */ 204 gssbuf.length = 20; /* yes, it's always 20 (SHA-1) */ 205 gssbuf.value = hash; /* and it's static constant storage */ 206 207 if (GSS_ERROR(ssh_gssapi_get_mic(ctxt,&gssbuf,&msg_tok))) { 208 kex_gss_send_error(ctxt); 209 fatal("Couldn't get MIC"); 210 } 211 212 packet_start(SSH2_MSG_KEXGSS_COMPLETE); 213 packet_put_bignum2(dh->pub_key); 214 packet_put_string((char *)msg_tok.value,msg_tok.length); 215 (void) gss_release_buffer(&min_status, &msg_tok); 216 217 if (send_tok.length != 0) { 218 packet_put_char(1); /* true */ 219 packet_put_string((char *)send_tok.value,send_tok.length); 220 (void) gss_release_buffer(&min_status, &send_tok); 221 } else { 222 packet_put_char(0); /* false */ 223 } 224 packet_send(); 225 packet_write_wait(); 226 227 DH_free(dh); 228 229 kex_derive_keys(kex, hash, shared_secret); 230 BN_clear_free(shared_secret); 231 kex_finish(kex); 232 } 233 234 static void 235 kex_gss_send_error(Gssctxt *ctxt) { 236 char *errstr; 237 OM_uint32 maj,min; 238 239 errstr = ssh_gssapi_last_error(ctxt,&maj,&min); 240 if (errstr) { 241 packet_start(SSH2_MSG_KEXGSS_ERROR); 242 packet_put_int(maj); 243 packet_put_int(min); 244 packet_put_cstring(errstr); 245 packet_put_cstring(""); 246 packet_send(); 247 packet_write_wait(); 248 /* XXX - We should probably log the error locally here */ 249 xfree(errstr); 250 } 251 } 252 #endif /* GSSAPI */ 253