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 2007 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 "auth.h" 49 50 Gssctxt *xxx_gssctxt; 51 extern Authctxt *x_authctxt; 52 53 static void kex_gss_send_error(Gssctxt *ctxt); 54 55 void 56 kexgss_server(Kex *kex) 57 { 58 OM_uint32 maj_status, min_status; 59 gss_buffer_desc gssbuf, send_tok, recv_tok, msg_tok; 60 Gssctxt *ctxt = NULL; 61 unsigned int klen, kout; 62 unsigned int sbloblen = 0; 63 unsigned char *kbuf, *hash; 64 unsigned char *server_host_key_blob = NULL; 65 DH *dh; 66 Key *server_host_key = NULL; 67 BIGNUM *shared_secret = NULL; 68 BIGNUM *dh_client_pub = NULL; 69 int type =0; 70 u_int slen; 71 gss_OID oid; 72 73 /* 74 * Load host key to advertise in a SSH_MSG_KEXGSS_HOSTKEY packet 75 * -- unlike KEX_DH/KEX_GEX no host key, no problem since it's 76 * the GSS-API that provides for server host authentication. 77 */ 78 if (kex->load_host_key != NULL && 79 !(datafellows & SSH_BUG_GSSKEX_HOSTKEY)) 80 server_host_key = kex->load_host_key(kex->hostkey_type); 81 if (server_host_key != NULL) 82 key_to_blob(server_host_key, &server_host_key_blob, &sbloblen); 83 84 85 /* Initialise GSSAPI */ 86 87 ssh_gssapi_oid_of_kexname(kex->name, &oid); 88 if (oid == GSS_C_NULL_OID) { 89 fatal("Couldn't match the negotiated GSS key exchange"); 90 } 91 92 ssh_gssapi_build_ctx(&xxx_gssctxt, 0, oid); 93 94 ctxt = xxx_gssctxt; 95 96 do { 97 debug("Wait SSH2_MSG_GSSAPI_INIT"); 98 type = packet_read(); 99 switch(type) { 100 case SSH2_MSG_KEXGSS_INIT: 101 if (dh_client_pub!=NULL) 102 fatal("Received KEXGSS_INIT after initialising"); 103 recv_tok.value=packet_get_string(&slen); 104 recv_tok.length=slen; /* int vs. size_t */ 105 106 dh_client_pub = BN_new(); 107 108 if (dh_client_pub == NULL) 109 fatal("dh_client_pub == NULL"); 110 packet_get_bignum2(dh_client_pub); 111 112 /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */ 113 if (sbloblen) { 114 packet_start(SSH2_MSG_KEXGSS_HOSTKEY); 115 packet_put_string(server_host_key_blob, sbloblen); 116 packet_send(); 117 packet_write_wait(); 118 } 119 break; 120 case SSH2_MSG_KEXGSS_CONTINUE: 121 recv_tok.value=packet_get_string(&slen); 122 recv_tok.length=slen; /* int vs. size_t */ 123 break; 124 default: 125 packet_disconnect("Protocol error: didn't expect packet type %d", 126 type); 127 } 128 129 maj_status = ssh_gssapi_accept_ctx(ctxt,&recv_tok, &send_tok); 130 131 xfree(recv_tok.value); /* We allocated this, not gss */ 132 133 if (dh_client_pub == NULL) 134 fatal("No client public key"); 135 136 if (maj_status == GSS_S_CONTINUE_NEEDED) { 137 debug("Sending GSSAPI_CONTINUE"); 138 packet_start(SSH2_MSG_KEXGSS_CONTINUE); 139 packet_put_string(send_tok.value,send_tok.length); 140 packet_send(); 141 packet_write_wait(); 142 (void) gss_release_buffer(&min_status, &send_tok); 143 } 144 } while (maj_status == GSS_S_CONTINUE_NEEDED); 145 146 if (GSS_ERROR(maj_status)) { 147 kex_gss_send_error(ctxt); 148 if (send_tok.length>0) { 149 packet_start(SSH2_MSG_KEXGSS_CONTINUE); 150 packet_put_string(send_tok.value,send_tok.length); 151 packet_send(); 152 packet_write_wait(); 153 (void) gss_release_buffer(&min_status, &send_tok); 154 } 155 fatal("accept_ctx died"); 156 } 157 158 debug("gss_complete"); 159 if (!(ctxt->flags & GSS_C_MUTUAL_FLAG)) 160 fatal("Mutual authentication flag wasn't set"); 161 162 if (!(ctxt->flags & GSS_C_INTEG_FLAG)) 163 fatal("Integrity flag wasn't set"); 164 165 dh = dh_new_group1(); 166 dh_gen_key(dh, kex->we_need * 8); 167 168 if (!dh_pub_is_valid(dh, dh_client_pub)) 169 packet_disconnect("bad client public DH value"); 170 171 klen = DH_size(dh); 172 kbuf = xmalloc(klen); 173 kout = DH_compute_key(kbuf, dh_client_pub, dh); 174 175 shared_secret = BN_new(); 176 BN_bin2bn(kbuf, kout, shared_secret); 177 (void) memset(kbuf, 0, klen); 178 xfree(kbuf); 179 180 /* The GSSAPI hash is identical to the Diffie Helman one */ 181 hash = kex_dh_hash( 182 kex->client_version_string, 183 kex->server_version_string, 184 buffer_ptr(&kex->peer), buffer_len(&kex->peer), 185 buffer_ptr(&kex->my), buffer_len(&kex->my), 186 server_host_key_blob, sbloblen, 187 dh_client_pub, 188 dh->pub_key, 189 shared_secret 190 ); 191 BN_free(dh_client_pub); 192 193 if (kex->session_id == NULL) { 194 kex->session_id_len = 20; 195 kex->session_id = xmalloc(kex->session_id_len); 196 (void) memcpy(kex->session_id, hash, kex->session_id_len); 197 } else if (x_authctxt != NULL && x_authctxt->success) { 198 ssh_gssapi_storecreds(ctxt, x_authctxt); 199 } 200 201 /* Should fix kex_dh_hash to output hash length */ 202 gssbuf.length = 20; /* yes, it's always 20 (SHA-1) */ 203 gssbuf.value = hash; /* and it's static constant storage */ 204 205 if (GSS_ERROR(ssh_gssapi_get_mic(ctxt,&gssbuf,&msg_tok))) { 206 kex_gss_send_error(ctxt); 207 fatal("Couldn't get MIC"); 208 } 209 210 packet_start(SSH2_MSG_KEXGSS_COMPLETE); 211 packet_put_bignum2(dh->pub_key); 212 packet_put_string((char *)msg_tok.value,msg_tok.length); 213 (void) gss_release_buffer(&min_status, &msg_tok); 214 215 if (send_tok.length != 0) { 216 packet_put_char(1); /* true */ 217 packet_put_string((char *)send_tok.value,send_tok.length); 218 (void) gss_release_buffer(&min_status, &send_tok); 219 } else { 220 packet_put_char(0); /* false */ 221 } 222 packet_send(); 223 packet_write_wait(); 224 225 DH_free(dh); 226 227 kex_derive_keys(kex, hash, shared_secret); 228 BN_clear_free(shared_secret); 229 kex_finish(kex); 230 } 231 232 static void 233 kex_gss_send_error(Gssctxt *ctxt) { 234 char *errstr; 235 OM_uint32 maj,min; 236 237 errstr = ssh_gssapi_last_error(ctxt,&maj,&min); 238 if (errstr) { 239 packet_start(SSH2_MSG_KEXGSS_ERROR); 240 packet_put_int(maj); 241 packet_put_int(min); 242 packet_put_cstring(errstr); 243 packet_put_cstring(""); 244 packet_send(); 245 packet_write_wait(); 246 /* XXX - We should probably log the error locally here */ 247 xfree(errstr); 248 } 249 } 250 #endif /* GSSAPI */ 251