1 /* $OpenBSD: gss-genr.c,v 1.17 2006/08/29 12:02:30 dtucker Exp $ */
4 * Copyright (c) 2001-2006 Simon Wilkinson. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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.
31 #include <sys/types.h>
32 #include <sys/param.h>
45 #include <openssl/evp.h>
49 extern u_char *session_id2;
50 extern u_int session_id2_len;
55 } ssh_gss_kex_mapping;
58 * XXX - It would be nice to find a more elegant way of handling the
59 * XXX passing of the key exchange context to the userauth routines
62 Gssctxt *gss_kex_context = NULL;
64 static ssh_gss_kex_mapping *gss_enc2oid = NULL;
67 ssh_gssapi_oid_table_ok() {
68 return (gss_enc2oid != NULL);
72 * Return a list of the gss-group1-sha1 mechanisms supported by this program
74 * We test mechanisms to ensure that we can use them, to avoid starting
75 * a key exchange with a bad mechanism
79 ssh_gssapi_client_mechanisms(const char *host) {
80 gss_OID_set gss_supported;
83 gss_indicate_mechs(&min_status, &gss_supported);
85 return(ssh_gssapi_kex_mechs(gss_supported, ssh_gssapi_check_mechanism,
90 ssh_gssapi_kex_mechs(gss_OID_set gss_supported, ssh_gssapi_check_fn *check,
95 char *mechs, *encoded;
96 u_char digest[EVP_MAX_MD_SIZE];
98 const EVP_MD *evp_md = EVP_md5();
101 if (gss_enc2oid != NULL) {
102 for (i = 0; gss_enc2oid[i].encoded != NULL; i++)
103 xfree(gss_enc2oid[i].encoded);
107 gss_enc2oid = xmalloc(sizeof(ssh_gss_kex_mapping) *
108 (gss_supported->count + 1));
113 for (i = 0; i < gss_supported->count; i++) {
114 if (gss_supported->elements[i].length < 128 &&
115 (*check)(NULL, &(gss_supported->elements[i]), data)) {
117 deroid[0] = SSH_GSS_OIDTYPE;
118 deroid[1] = gss_supported->elements[i].length;
120 EVP_DigestInit(&md, evp_md);
121 EVP_DigestUpdate(&md, deroid, 2);
122 EVP_DigestUpdate(&md,
123 gss_supported->elements[i].elements,
124 gss_supported->elements[i].length);
125 EVP_DigestFinal(&md, digest, NULL);
127 encoded = xmalloc(EVP_MD_size(evp_md) * 2);
128 enclen = __b64_ntop(digest, EVP_MD_size(evp_md),
129 encoded, EVP_MD_size(evp_md) * 2);
132 buffer_put_char(&buf, ',');
134 buffer_append(&buf, KEX_GSS_GEX_SHA1_ID,
135 sizeof(KEX_GSS_GEX_SHA1_ID) - 1);
136 buffer_append(&buf, encoded, enclen);
137 buffer_put_char(&buf, ',');
138 buffer_append(&buf, KEX_GSS_GRP1_SHA1_ID,
139 sizeof(KEX_GSS_GRP1_SHA1_ID) - 1);
140 buffer_append(&buf, encoded, enclen);
141 buffer_put_char(&buf, ',');
142 buffer_append(&buf, KEX_GSS_GRP14_SHA1_ID,
143 sizeof(KEX_GSS_GRP14_SHA1_ID) - 1);
144 buffer_append(&buf, encoded, enclen);
146 gss_enc2oid[oidpos].oid = &(gss_supported->elements[i]);
147 gss_enc2oid[oidpos].encoded = encoded;
151 gss_enc2oid[oidpos].oid = NULL;
152 gss_enc2oid[oidpos].encoded = NULL;
154 buffer_put_char(&buf, '\0');
156 mechs = xmalloc(buffer_len(&buf));
157 buffer_get(&buf, mechs, buffer_len(&buf));
160 if (strlen(mechs) == 0) {
169 ssh_gssapi_id_kex(Gssctxt *ctx, char *name, int kex_type) {
173 case KEX_GSS_GRP1_SHA1:
174 name += sizeof(KEX_GSS_GRP1_SHA1_ID) - 1;
176 case KEX_GSS_GRP14_SHA1:
177 name += sizeof(KEX_GSS_GRP14_SHA1_ID) - 1;
179 case KEX_GSS_GEX_SHA1:
180 name += sizeof(KEX_GSS_GEX_SHA1_ID) - 1;
186 while (gss_enc2oid[i].encoded != NULL &&
187 strcmp(name, gss_enc2oid[i].encoded) != 0)
190 if (gss_enc2oid[i].oid != NULL && ctx != NULL)
191 ssh_gssapi_set_oid(ctx, gss_enc2oid[i].oid);
193 return gss_enc2oid[i].oid;
196 /* Check that the OID in a data stream matches that in the context */
198 ssh_gssapi_check_oid(Gssctxt *ctx, void *data, size_t len)
200 return (ctx != NULL && ctx->oid != GSS_C_NO_OID &&
201 ctx->oid->length == len &&
202 memcmp(ctx->oid->elements, data, len) == 0);
205 /* Set the contexts OID from a data stream */
207 ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len)
209 if (ctx->oid != GSS_C_NO_OID) {
210 xfree(ctx->oid->elements);
213 ctx->oid = xmalloc(sizeof(gss_OID_desc));
214 ctx->oid->length = len;
215 ctx->oid->elements = xmalloc(len);
216 memcpy(ctx->oid->elements, data, len);
219 /* Set the contexts OID */
221 ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid)
223 ssh_gssapi_set_oid_data(ctx, oid->elements, oid->length);
226 /* All this effort to report an error ... */
228 ssh_gssapi_error(Gssctxt *ctxt)
232 s = ssh_gssapi_last_error(ctxt, NULL, NULL);
238 ssh_gssapi_last_error(Gssctxt *ctxt, OM_uint32 *major_status,
239 OM_uint32 *minor_status)
242 gss_buffer_desc msg = GSS_C_EMPTY_BUFFER;
249 if (major_status != NULL)
250 *major_status = ctxt->major;
251 if (minor_status != NULL)
252 *minor_status = ctxt->minor;
255 /* The GSSAPI error */
257 gss_display_status(&lmin, ctxt->major,
258 GSS_C_GSS_CODE, ctxt->oid, &ctx, &msg);
260 buffer_append(&b, msg.value, msg.length);
261 buffer_put_char(&b, '\n');
263 gss_release_buffer(&lmin, &msg);
266 /* The mechanism specific error */
268 gss_display_status(&lmin, ctxt->minor,
269 GSS_C_MECH_CODE, ctxt->oid, &ctx, &msg);
271 buffer_append(&b, msg.value, msg.length);
272 buffer_put_char(&b, '\n');
274 gss_release_buffer(&lmin, &msg);
277 buffer_put_char(&b, '\0');
278 ret = xmalloc(buffer_len(&b));
279 buffer_get(&b, ret, buffer_len(&b));
285 * Initialise our GSSAPI context. We use this opaque structure to contain all
286 * of the data which both the client and server need to persist across
287 * {accept,init}_sec_context calls, so that when we do it from the userauth
288 * stuff life is a little easier
291 ssh_gssapi_build_ctx(Gssctxt **ctx)
293 *ctx = xcalloc(1, sizeof (Gssctxt));
294 (*ctx)->context = GSS_C_NO_CONTEXT;
295 (*ctx)->name = GSS_C_NO_NAME;
296 (*ctx)->oid = GSS_C_NO_OID;
297 (*ctx)->creds = GSS_C_NO_CREDENTIAL;
298 (*ctx)->client = GSS_C_NO_NAME;
299 (*ctx)->client_creds = GSS_C_NO_CREDENTIAL;
302 /* Delete our context, providing it has been built correctly */
304 ssh_gssapi_delete_ctx(Gssctxt **ctx)
310 if ((*ctx)->context != GSS_C_NO_CONTEXT)
311 gss_delete_sec_context(&ms, &(*ctx)->context, GSS_C_NO_BUFFER);
312 if ((*ctx)->name != GSS_C_NO_NAME)
313 gss_release_name(&ms, &(*ctx)->name);
314 if ((*ctx)->oid != GSS_C_NO_OID) {
315 xfree((*ctx)->oid->elements);
317 (*ctx)->oid = GSS_C_NO_OID;
319 if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
320 gss_release_cred(&ms, &(*ctx)->creds);
321 if ((*ctx)->client != GSS_C_NO_NAME)
322 gss_release_name(&ms, &(*ctx)->client);
323 if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
324 gss_release_cred(&ms, &(*ctx)->client_creds);
331 * Wrapper to init_sec_context
332 * Requires that the context contains:
334 * server name (from ssh_gssapi_import_name)
337 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
338 gss_buffer_desc* send_tok, OM_uint32 *flags)
343 deleg_flag = GSS_C_DELEG_FLAG;
344 debug("Delegating credentials");
347 ctx->major = gss_init_sec_context(&ctx->minor,
348 GSS_C_NO_CREDENTIAL, &ctx->context, ctx->name, ctx->oid,
349 GSS_C_MUTUAL_FLAG | GSS_C_INTEG_FLAG | deleg_flag,
350 0, NULL, recv_tok, NULL, send_tok, flags, NULL);
352 if (GSS_ERROR(ctx->major))
353 ssh_gssapi_error(ctx);
358 /* Create a service name for the given host */
360 ssh_gssapi_import_name(Gssctxt *ctx, const char *host)
362 gss_buffer_desc gssbuf;
365 xasprintf(&val, "host@%s", host);
367 gssbuf.length = strlen(gssbuf.value);
369 if ((ctx->major = gss_import_name(&ctx->minor,
370 &gssbuf, GSS_C_NT_HOSTBASED_SERVICE, &ctx->name)))
371 ssh_gssapi_error(ctx);
378 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_t buffer, gss_buffer_t hash)
383 if ((ctx->major = gss_get_mic(&ctx->minor, ctx->context,
384 GSS_C_QOP_DEFAULT, buffer, hash)))
385 ssh_gssapi_error(ctx);
390 /* Priviledged when used by server */
392 ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
397 ctx->major = gss_verify_mic(&ctx->minor, ctx->context,
398 gssbuf, gssmic, NULL);
404 ssh_gssapi_buildmic(Buffer *b, const char *user, const char *service,
408 buffer_put_string(b, session_id2, session_id2_len);
409 buffer_put_char(b, SSH2_MSG_USERAUTH_REQUEST);
410 buffer_put_cstring(b, user);
411 buffer_put_cstring(b, service);
412 buffer_put_cstring(b, context);
416 ssh_gssapi_check_mechanism(Gssctxt **ctx, gss_OID oid, const char *host)
418 gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
419 OM_uint32 major, minor;
420 gss_OID_desc spnego_oid = {6, (void *)"\x2B\x06\x01\x05\x05\x02"};
421 Gssctxt *intctx = NULL;
426 /* RFC 4462 says we MUST NOT do SPNEGO */
427 if (oid->length == spnego_oid.length &&
428 (memcmp(oid->elements, spnego_oid.elements, oid->length) == 0))
429 return 0; /* false */
431 ssh_gssapi_build_ctx(ctx);
432 ssh_gssapi_set_oid(*ctx, oid);
433 major = ssh_gssapi_import_name(*ctx, host);
434 if (!GSS_ERROR(major)) {
435 major = ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token,
437 gss_release_buffer(&minor, &token);
438 if ((*ctx)->context != GSS_C_NO_CONTEXT)
439 gss_delete_sec_context(&minor, &(*ctx)->context,
443 if (GSS_ERROR(major) || intctx != NULL)
444 ssh_gssapi_delete_ctx(ctx);
446 return (!GSS_ERROR(major));