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540d72c3 | 1 | /* $OpenBSD: gss-genr.c,v 1.3 2003/11/21 11:57:03 djm Exp $ */ |
7cac2b65 | 2 | |
5598e598 | 3 | /* |
7cac2b65 | 4 | * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. |
5 | * | |
5598e598 | 6 | * Redistribution and use in source and binary forms, with or without |
7 | * modification, are permitted provided that the following conditions | |
8 | * are met: | |
9 | * 1. Redistributions of source code must retain the above copyright | |
10 | * notice, this list of conditions and the following disclaimer. | |
11 | * 2. Redistributions in binary form must reproduce the above copyright | |
12 | * notice, this list of conditions and the following disclaimer in the | |
13 | * documentation and/or other materials provided with the distribution. | |
14 | * | |
15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR | |
16 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
17 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
18 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
19 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
20 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
21 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
22 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
24 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
25 | */ | |
26 | ||
27 | #include "includes.h" | |
28 | ||
29 | #ifdef GSSAPI | |
30 | ||
5598e598 | 31 | #include "xmalloc.h" |
32 | #include "buffer.h" | |
33 | #include "bufaux.h" | |
5598e598 | 34 | #include "compat.h" |
35 | #include <openssl/evp.h> | |
5598e598 | 36 | #include "kex.h" |
37 | #include "log.h" | |
b59afbfe | 38 | #include "monitor_wrap.h" |
4dd35ca9 | 39 | #include "canohost.h" |
540d72c3 | 40 | #include "ssh2.h" |
5598e598 | 41 | |
42 | #include "ssh-gss.h" | |
43 | ||
540d72c3 | 44 | extern u_char *session_id2; |
45 | extern u_int session_id2_len; | |
46 | ||
23987cb8 | 47 | typedef struct { |
48 | char *encoded; | |
49 | gss_OID oid; | |
50 | } ssh_gss_kex_mapping; | |
51 | ||
52 | static ssh_gss_kex_mapping *gss_enc2oid; | |
5598e598 | 53 | |
54 | /* Return a list of the gss-group1-sha1-x mechanisms supported by this | |
55 | * program. | |
56 | * | |
23987cb8 | 57 | * On the client side, we don't need to worry about whether we 'know' |
58 | * about the mechanism or not - we assume that any mechanism that we've been | |
59 | * linked against is suitable for inclusion. | |
5598e598 | 60 | * |
23987cb8 | 61 | * XXX - We might want to make this configurable in the future, so as to |
62 | * XXX - allow the user control over which mechanisms to use. | |
5598e598 | 63 | */ |
64 | ||
65 | char * | |
23987cb8 | 66 | ssh_gssapi_client_mechanisms(char *host) { |
5598e598 | 67 | gss_OID_set supported; |
23987cb8 | 68 | OM_uint32 min_status; |
5598e598 | 69 | Buffer buf; |
70 | int i = 0; | |
23987cb8 | 71 | char *mechs; |
72 | char *encoded; | |
73 | int enclen; | |
74 | char digest[EVP_MAX_MD_SIZE]; | |
75 | char deroid[2]; | |
76 | const EVP_MD *evp_md = EVP_md5(); | |
77 | EVP_MD_CTX md; | |
78 | int oidpos=0; | |
79 | ||
23987cb8 | 80 | gss_indicate_mechs(&min_status,&supported); |
dfddba3d | 81 | gss_enc2oid=xmalloc(sizeof(ssh_gss_kex_mapping) |
82 | *(supported->count+1)); | |
5598e598 | 83 | |
23987cb8 | 84 | buffer_init(&buf); |
85 | ||
23987cb8 | 86 | for (i=0;i<supported->count;i++) { |
87 | ||
88 | gss_enc2oid[oidpos].encoded=NULL; | |
89 | ||
90 | if (supported->elements[i].length<128 && | |
91 | ssh_gssapi_check_mechanism(&(supported->elements[i]),host)) { | |
92 | ||
23987cb8 | 93 | /* Add the required DER encoding octets and MD5 hash */ |
94 | deroid[0]=0x06; /* Object Identifier */ | |
95 | deroid[1]=supported->elements[i].length; | |
96 | ||
97 | EVP_DigestInit(&md, evp_md); | |
98 | EVP_DigestUpdate(&md,deroid,2); | |
99 | EVP_DigestUpdate(&md, | |
e23e524c | 100 | supported->elements[i].elements, |
101 | supported->elements[i].length); | |
23987cb8 | 102 | EVP_DigestFinal(&md, digest, NULL); |
103 | ||
104 | /* Base64 encode it */ | |
105 | encoded=xmalloc(EVP_MD_size(evp_md)*2); | |
106 | enclen=__b64_ntop(digest, EVP_MD_size(evp_md), | |
107 | encoded,EVP_MD_size(evp_md)*2); | |
108 | if (oidpos!=0) { | |
109 | buffer_put_char(&buf,','); | |
110 | } | |
111 | buffer_append(&buf, KEX_GSS_SHA1, sizeof(KEX_GSS_SHA1)-1); | |
112 | buffer_append(&buf, encoded, enclen); | |
113 | ||
114 | debug("Mechanism encoded as %s",encoded); | |
115 | ||
116 | gss_enc2oid[oidpos].oid=&(supported->elements[i]); | |
117 | gss_enc2oid[oidpos].encoded=encoded; | |
118 | oidpos++; | |
d4ab470d | 119 | } |
23987cb8 | 120 | } |
121 | gss_enc2oid[oidpos].oid=NULL; | |
122 | gss_enc2oid[oidpos].encoded=NULL; | |
5598e598 | 123 | |
124 | buffer_put_char(&buf,'\0'); | |
125 | ||
126 | mechs=xmalloc(buffer_len(&buf)); | |
127 | buffer_get(&buf,mechs,buffer_len(&buf)); | |
128 | buffer_free(&buf); | |
129 | if (strlen(mechs)==0) | |
23987cb8 | 130 | return(NULL); |
5598e598 | 131 | else |
23987cb8 | 132 | return(mechs); |
133 | } | |
134 | ||
135 | gss_OID | |
136 | ssh_gssapi_client_id_kex(Gssctxt *ctx, char *name) { | |
137 | int i=0; | |
138 | ||
139 | if (strncmp(name, KEX_GSS_SHA1, sizeof(KEX_GSS_SHA1)-1) !=0) { | |
140 | return(NULL); | |
141 | } | |
142 | ||
143 | name+=sizeof(KEX_GSS_SHA1)-1; /* Move to the start of the ID string */ | |
144 | ||
145 | while (gss_enc2oid[i].encoded!=NULL && | |
146 | strcmp(name,gss_enc2oid[i].encoded)!=0) { | |
147 | i++; | |
148 | } | |
149 | ||
150 | if (gss_enc2oid[i].oid!=NULL) { | |
151 | ssh_gssapi_set_oid(ctx,gss_enc2oid[i].oid); | |
152 | } | |
153 | ||
154 | return gss_enc2oid[i].oid; | |
5598e598 | 155 | } |
156 | ||
23987cb8 | 157 | /* Check that the OID in a data stream matches that in the context */ |
7cac2b65 | 158 | int |
159 | ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len) | |
160 | { | |
161 | return (ctx != NULL && ctx->oid != GSS_C_NO_OID && | |
162 | ctx->oid->length == len && | |
163 | memcmp(ctx->oid->elements, data, len) == 0); | |
23987cb8 | 164 | } |
7cac2b65 | 165 | |
5598e598 | 166 | /* Set the contexts OID from a data stream */ |
7cac2b65 | 167 | void |
168 | ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) | |
169 | { | |
170 | if (ctx->oid != GSS_C_NO_OID) { | |
171 | xfree(ctx->oid->elements); | |
172 | xfree(ctx->oid); | |
173 | } | |
174 | ctx->oid = xmalloc(sizeof(gss_OID_desc)); | |
175 | ctx->oid->length = len; | |
176 | ctx->oid->elements = xmalloc(len); | |
177 | memcpy(ctx->oid->elements, data, len); | |
5598e598 | 178 | } |
179 | ||
180 | /* Set the contexts OID */ | |
7cac2b65 | 181 | void |
182 | ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) | |
183 | { | |
184 | ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length); | |
5598e598 | 185 | } |
186 | ||
23987cb8 | 187 | /* All this effort to report an error ... */ |
23987cb8 | 188 | void |
7cac2b65 | 189 | ssh_gssapi_error(Gssctxt *ctxt) |
190 | { | |
191 | debug("%s", ssh_gssapi_last_error(ctxt, NULL, NULL)); | |
5598e598 | 192 | } |
193 | ||
23987cb8 | 194 | char * |
7cac2b65 | 195 | ssh_gssapi_last_error(Gssctxt *ctxt, |
196 | OM_uint32 *major_status, OM_uint32 *minor_status) | |
197 | { | |
23987cb8 | 198 | OM_uint32 lmin; |
7cac2b65 | 199 | gss_buffer_desc msg = GSS_C_EMPTY_BUFFER; |
200 | OM_uint32 ctx; | |
201 | Buffer b; | |
202 | char *ret; | |
203 | ||
204 | buffer_init(&b); | |
205 | ||
206 | if (major_status != NULL) | |
207 | *major_status = ctxt->major; | |
208 | if (minor_status != NULL) | |
209 | *minor_status = ctxt->minor; | |
210 | ||
211 | ctx = 0; | |
5598e598 | 212 | /* The GSSAPI error */ |
7cac2b65 | 213 | do { |
214 | gss_display_status(&lmin, ctxt->major, | |
215 | GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg); | |
216 | ||
217 | buffer_append(&b, msg.value, msg.length); | |
218 | buffer_put_char(&b, '\n'); | |
219 | ||
220 | gss_release_buffer(&lmin, &msg); | |
221 | } while (ctx != 0); | |
222 | ||
223 | /* The mechanism specific error */ | |
224 | do { | |
225 | gss_display_status(&lmin, ctxt->minor, | |
226 | GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg); | |
227 | ||
228 | buffer_append(&b, msg.value, msg.length); | |
229 | buffer_put_char(&b, '\n'); | |
230 | ||
231 | gss_release_buffer(&lmin, &msg); | |
232 | } while (ctx != 0); | |
233 | ||
234 | buffer_put_char(&b, '\0'); | |
235 | ret = xmalloc(buffer_len(&b)); | |
236 | buffer_get(&b, ret, buffer_len(&b)); | |
237 | buffer_free(&b); | |
238 | return (ret); | |
5598e598 | 239 | } |
240 | ||
7cac2b65 | 241 | /* |
242 | * Initialise our GSSAPI context. We use this opaque structure to contain all | |
5598e598 | 243 | * of the data which both the client and server need to persist across |
244 | * {accept,init}_sec_context calls, so that when we do it from the userauth | |
245 | * stuff life is a little easier | |
246 | */ | |
247 | void | |
b59afbfe | 248 | ssh_gssapi_build_ctx(Gssctxt **ctx) |
5598e598 | 249 | { |
7cac2b65 | 250 | *ctx = xmalloc(sizeof (Gssctxt)); |
251 | (*ctx)->major = 0; | |
252 | (*ctx)->minor = 0; | |
253 | (*ctx)->context = GSS_C_NO_CONTEXT; | |
254 | (*ctx)->name = GSS_C_NO_NAME; | |
255 | (*ctx)->oid = GSS_C_NO_OID; | |
256 | (*ctx)->creds = GSS_C_NO_CREDENTIAL; | |
257 | (*ctx)->client = GSS_C_NO_NAME; | |
258 | (*ctx)->client_creds = GSS_C_NO_CREDENTIAL; | |
5598e598 | 259 | } |
260 | ||
261 | /* Delete our context, providing it has been built correctly */ | |
262 | void | |
b59afbfe | 263 | ssh_gssapi_delete_ctx(Gssctxt **ctx) |
5598e598 | 264 | { |
9eeaa28e | 265 | #if !defined(MECHGLUE) |
5598e598 | 266 | OM_uint32 ms; |
9eeaa28e | 267 | #endif |
7cac2b65 | 268 | |
269 | if ((*ctx) == NULL) | |
b59afbfe | 270 | return; |
d4ab470d | 271 | #if !defined(MECHGLUE) /* mechglue has some memory management issues */ |
7cac2b65 | 272 | if ((*ctx)->context != GSS_C_NO_CONTEXT) |
273 | gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER); | |
b59afbfe | 274 | if ((*ctx)->name != GSS_C_NO_NAME) |
7cac2b65 | 275 | gss_release_name(&ms, &(*ctx)->name); |
b59afbfe | 276 | if ((*ctx)->oid != GSS_C_NO_OID) { |
277 | xfree((*ctx)->oid->elements); | |
278 | xfree((*ctx)->oid); | |
279 | (*ctx)->oid = GSS_C_NO_OID; | |
5598e598 | 280 | } |
b59afbfe | 281 | if ((*ctx)->creds != GSS_C_NO_CREDENTIAL) |
7cac2b65 | 282 | gss_release_cred(&ms, &(*ctx)->creds); |
b59afbfe | 283 | if ((*ctx)->client != GSS_C_NO_NAME) |
7cac2b65 | 284 | gss_release_name(&ms, &(*ctx)->client); |
b59afbfe | 285 | if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL) |
7cac2b65 | 286 | gss_release_cred(&ms, &(*ctx)->client_creds); |
d4ab470d | 287 | #endif |
7cac2b65 | 288 | |
b59afbfe | 289 | xfree(*ctx); |
7cac2b65 | 290 | *ctx = NULL; |
5598e598 | 291 | } |
292 | ||
7cac2b65 | 293 | /* |
294 | * Wrapper to init_sec_context | |
5598e598 | 295 | * Requires that the context contains: |
296 | * oid | |
7cac2b65 | 297 | * server name (from ssh_gssapi_import_name) |
5598e598 | 298 | */ |
7cac2b65 | 299 | OM_uint32 |
5598e598 | 300 | ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok, |
7cac2b65 | 301 | gss_buffer_desc* send_tok, OM_uint32 *flags) |
5598e598 | 302 | { |
5598e598 | 303 | int deleg_flag = 0; |
7cac2b65 | 304 | |
5598e598 | 305 | if (deleg_creds) { |
7cac2b65 | 306 | deleg_flag = GSS_C_DELEG_FLAG; |
5598e598 | 307 | debug("Delegating credentials"); |
308 | } | |
7cac2b65 | 309 | |
310 | ctx->major = gss_init_sec_context(&ctx->minor, | |
311 | GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid, | |
312 | GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag, | |
313 | 0, NULL, recv_tok, NULL, send_tok, flags, NULL); | |
314 | ||
315 | if (GSS_ERROR(ctx->major)) | |
316 | ssh_gssapi_error(ctx); | |
317 | ||
318 | return (ctx->major); | |
5598e598 | 319 | } |
320 | ||
5598e598 | 321 | /* Create a service name for the given host */ |
322 | OM_uint32 | |
7cac2b65 | 323 | ssh_gssapi_import_name(Gssctxt *ctx, const char *host) |
324 | { | |
23987cb8 | 325 | gss_buffer_desc gssbuf; |
4dd35ca9 | 326 | char *xhost; |
7cac2b65 | 327 | |
5598e598 | 328 | /* Make a copy of the host name, in case it was returned by a |
e23e524c | 329 | * previous call to gethostbyname(). */ |
5598e598 | 330 | xhost = xstrdup(host); |
331 | ||
23987cb8 | 332 | /* Make sure we have the FQDN. Some GSSAPI implementations don't do |
e23e524c | 333 | * this for us themselves */ |
1df48666 | 334 | resolve_localhost(&xhost); |
23987cb8 | 335 | |
7cac2b65 | 336 | gssbuf.length = sizeof("host@") + strlen(xhost); |
337 | gssbuf.value = xmalloc(gssbuf.length); | |
5682ddfd | 338 | snprintf(gssbuf.value, gssbuf.length, "host@%s", xhost); |
7cac2b65 | 339 | |
340 | if ((ctx->major = gss_import_name(&ctx->minor, | |
341 | &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name))) | |
23987cb8 | 342 | ssh_gssapi_error(ctx); |
7cac2b65 | 343 | |
1c828c5c | 344 | xfree(xhost); |
5598e598 | 345 | xfree(gssbuf.value); |
7cac2b65 | 346 | return (ctx->major); |
5598e598 | 347 | } |
348 | ||
349 | /* Acquire credentials for a server running on the current host. | |
350 | * Requires that the context structure contains a valid OID | |
b59afbfe | 351 | */ |
7cac2b65 | 352 | |
b59afbfe | 353 | /* Returns a GSSAPI error code */ |
5598e598 | 354 | OM_uint32 |
7cac2b65 | 355 | ssh_gssapi_acquire_cred(Gssctxt *ctx) |
356 | { | |
23987cb8 | 357 | OM_uint32 status; |
5598e598 | 358 | char lname[MAXHOSTNAMELEN]; |
359 | gss_OID_set oidset; | |
5598e598 | 360 | |
7cac2b65 | 361 | gss_create_empty_oid_set(&status, &oidset); |
362 | gss_add_oid_set_member(&status, ctx->oid, &oidset); | |
363 | ||
364 | if (gethostname(lname, MAXHOSTNAMELEN)) | |
365 | return (-1); | |
366 | ||
367 | if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) | |
368 | return (ctx->major); | |
369 | ||
370 | if ((ctx->major = gss_acquire_cred(&ctx->minor, | |
371 | ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL))) | |
23987cb8 | 372 | ssh_gssapi_error(ctx); |
7cac2b65 | 373 | |
23987cb8 | 374 | gss_release_oid_set(&status, &oidset); |
7cac2b65 | 375 | return (ctx->major); |
376 | } | |
377 | ||
540d72c3 | 378 | OM_uint32 |
379 | ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash) | |
380 | { | |
381 | if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context, | |
382 | GSS_C_QOP_DEFAULT, buffer, hash))) | |
383 | ssh_gssapi_error(ctx); | |
384 | ||
385 | return (ctx->major); | |
386 | } | |
387 | ||
388 | void | |
389 | ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service, | |
390 | const char *context) | |
391 | { | |
392 | buffer_init(b); | |
393 | buffer_put_string(b, session_id2, session_id2_len); | |
394 | buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST); | |
395 | buffer_put_cstring(b, user); | |
396 | buffer_put_cstring(b, service); | |
397 | buffer_put_cstring(b, context); | |
398 | } | |
399 | ||
7cac2b65 | 400 | OM_uint32 |
401 | ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) { | |
402 | if (*ctx) | |
403 | ssh_gssapi_delete_ctx(ctx); | |
404 | ssh_gssapi_build_ctx(ctx); | |
405 | ssh_gssapi_set_oid(*ctx, oid); | |
406 | return (ssh_gssapi_acquire_cred(*ctx)); | |
5598e598 | 407 | } |
b59afbfe | 408 | |
23987cb8 | 409 | int |
40883c8b | 410 | ssh_gssapi_check_mechanism(gss_OID oid, const char *host) { |
23987cb8 | 411 | Gssctxt * ctx = NULL; |
412 | gss_buffer_desc token; | |
413 | OM_uint32 major,minor; | |
414 | ||
415 | ssh_gssapi_build_ctx(&ctx); | |
416 | ssh_gssapi_set_oid(ctx,oid); | |
417 | ssh_gssapi_import_name(ctx,host); | |
418 | major=ssh_gssapi_init_ctx(ctx,0, GSS_C_NO_BUFFER, &token, NULL); | |
b59afbfe | 419 | gss_release_buffer(&minor,&token); |
23987cb8 | 420 | ssh_gssapi_delete_ctx(&ctx); |
421 | return(!GSS_ERROR(major)); | |
b59afbfe | 422 | } |
f001f132 | 423 | |
5598e598 | 424 | #endif /* GSSAPI */ |