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2ce0bfe4 | 1 | /* $OpenBSD: gss-serv.c,v 1.8 2005/08/30 22:08:05 djm Exp $ */ |
7cac2b65 | 2 | |
5598e598 | 3 | /* |
23987cb8 | 4 | * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. |
5598e598 | 5 | * |
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 "buffer.h" |
32 | #include "bufaux.h" | |
5598e598 | 33 | #include "compat.h" |
34 | #include <openssl/evp.h> | |
5598e598 | 35 | #include "kex.h" |
36 | #include "auth.h" | |
37 | #include "log.h" | |
e5affddc | 38 | #include "channels.h" |
5598e598 | 39 | #include "session.h" |
5598e598 | 40 | #include "servconf.h" |
b59afbfe | 41 | #include "monitor_wrap.h" |
7cac2b65 | 42 | #include "xmalloc.h" |
43 | #include "getput.h" | |
5598e598 | 44 | |
45 | #include "ssh-gss.h" | |
46 | ||
47 | extern ServerOptions options; | |
5598e598 | 48 | |
23987cb8 | 49 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 50 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
51 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 52 | |
7cac2b65 | 53 | ssh_gssapi_mech gssapi_null_mech = |
54 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 55 | |
5598e598 | 56 | #ifdef KRB5 |
23987cb8 | 57 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 58 | #endif |
5598e598 | 59 | #ifdef GSI |
23987cb8 | 60 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 61 | #endif |
62 | ||
23987cb8 | 63 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 64 | #ifdef KRB5 |
7cac2b65 | 65 | &gssapi_kerberos_mech, |
5598e598 | 66 | #endif |
67 | #ifdef GSI | |
7cac2b65 | 68 | &gssapi_gsi_mech, |
7b5a625b | 69 | #endif |
7cac2b65 | 70 | &gssapi_null_mech, |
23987cb8 | 71 | }; |
5598e598 | 72 | |
b4cfa386 | 73 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
74 | static int limited = 0; | |
75 | #endif | |
76 | ||
fe4ad273 | 77 | /* Unpriviledged */ |
78 | char * | |
79 | ssh_gssapi_server_mechanisms() { | |
80 | gss_OID_set supported; | |
81 | ||
82 | ssh_gssapi_supported_oids(&supported); | |
83 | return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, | |
84 | NULL)); | |
85 | } | |
86 | ||
87 | /* Unpriviledged */ | |
88 | int | |
89 | ssh_gssapi_server_check_mech(gss_OID oid, void *data) { | |
90 | Gssctxt * ctx = NULL; | |
91 | int res; | |
92 | ||
93 | res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); | |
94 | ssh_gssapi_delete_ctx(&ctx); | |
95 | ||
96 | return (res); | |
97 | } | |
98 | ||
7cac2b65 | 99 | /* Unpriviledged */ |
100 | void | |
101 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
102 | { | |
103 | int i = 0; | |
104 | OM_uint32 min_status; | |
105 | int present; | |
106 | gss_OID_set supported; | |
107 | ||
108 | gss_create_empty_oid_set(&min_status, oidset); | |
186e1568 | 109 | /* Ask priviledged process what mechanisms it supports. */ |
110 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
7cac2b65 | 111 | |
112 | while (supported_mechs[i]->name != NULL) { | |
113 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
114 | &supported_mechs[i]->oid, supported, &present))) | |
115 | present = 0; | |
116 | if (present) | |
117 | gss_add_oid_set_member(&min_status, | |
118 | &supported_mechs[i]->oid, oidset); | |
119 | i++; | |
120 | } | |
121 | } | |
122 | ||
123 | ||
124 | /* Wrapper around accept_sec_context | |
125 | * Requires that the context contains: | |
126 | * oid | |
127 | * credentials (from ssh_gssapi_acquire_cred) | |
128 | */ | |
129 | /* Priviledged */ | |
130 | OM_uint32 | |
131 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
132 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
133 | { | |
134 | OM_uint32 status; | |
135 | gss_OID mech; | |
136 | ||
137 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
138 | &ctx->context, ctx->creds, recv_tok, | |
139 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
140 | send_tok, flags, NULL, &ctx->client_creds); | |
141 | ||
142 | if (GSS_ERROR(ctx->major)) | |
143 | ssh_gssapi_error(ctx); | |
144 | ||
145 | if (ctx->client_creds) | |
146 | debug("Received some client credentials"); | |
147 | else | |
148 | debug("Got no client credentials"); | |
149 | ||
150 | status = ctx->major; | |
151 | ||
152 | /* Now, if we're complete and we have the right flags, then | |
153 | * we flag the user as also having been authenticated | |
154 | */ | |
155 | ||
156 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
157 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
158 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
159 | fatal("Couldn't convert client name"); | |
b4cfa386 | 160 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
161 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
162 | limited=1; | |
163 | #endif | |
7cac2b65 | 164 | } |
165 | ||
166 | return (status); | |
167 | } | |
168 | ||
169 | /* | |
170 | * This parses an exported name, extracting the mechanism specific portion | |
171 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
172 | * originally selected. | |
173 | */ | |
174 | static OM_uint32 | |
175 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
176 | { | |
2ce0bfe4 | 177 | u_char *tok; |
7cac2b65 | 178 | OM_uint32 offset; |
179 | OM_uint32 oidl; | |
180 | ||
181 | tok=ename->value; | |
182 | ||
183 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
184 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
185 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
186 | gssapi_gsi_mech.oid.length) == 0)) { | |
187 | name->length = ename->length; | |
188 | name->value = xmalloc(ename->length+1); | |
189 | memcpy(name->value, ename->value, ename->length); | |
190 | return GSS_S_COMPLETE; | |
191 | } | |
192 | #endif | |
193 | ||
194 | /* | |
195 | * Check that ename is long enough for all of the fixed length | |
196 | * header, and that the initial ID bytes are correct | |
197 | */ | |
198 | ||
199 | if (ename->length<6 || memcmp(tok,"\x04\x01", 2)!=0) | |
200 | return GSS_S_FAILURE; | |
201 | ||
202 | /* | |
203 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
204 | * and does use the OID type and length bytes. To confuse things | |
205 | * there are two lengths - the first including these, and the | |
206 | * second without. | |
207 | */ | |
208 | ||
209 | oidl = GET_16BIT(tok+2); /* length including next two bytes */ | |
210 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ | |
211 | ||
212 | /* | |
213 | * Check the BER encoding for correct type and length, that the | |
214 | * string is long enough and that the OID matches that in our context | |
215 | */ | |
216 | if (tok[4] != 0x06 || tok[5] != oidl || | |
217 | ename->length < oidl+6 || | |
2ce0bfe4 | 218 | !ssh_gssapi_check_oid(ctx,tok+6,oidl)) |
7cac2b65 | 219 | return GSS_S_FAILURE; |
220 | ||
221 | offset = oidl+6; | |
222 | ||
223 | if (ename->length < offset+4) | |
224 | return GSS_S_FAILURE; | |
225 | ||
226 | name->length = GET_32BIT(tok+offset); | |
227 | offset += 4; | |
228 | ||
229 | if (ename->length < offset+name->length) | |
230 | return GSS_S_FAILURE; | |
231 | ||
232 | name->value = xmalloc(name->length+1); | |
233 | memcpy(name->value,tok+offset,name->length); | |
234 | ((char *)name->value)[name->length] = 0; | |
235 | ||
236 | return GSS_S_COMPLETE; | |
237 | } | |
238 | ||
239 | /* Extract the client details from a given context. This can only reliably | |
240 | * be called once for a context */ | |
241 | ||
242 | /* Priviledged (called from accept_secure_ctx) */ | |
243 | OM_uint32 | |
244 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
245 | { | |
246 | int i = 0; | |
247 | ||
248 | gss_buffer_desc ename; | |
249 | ||
250 | client->mech = NULL; | |
251 | ||
252 | while (supported_mechs[i]->name != NULL) { | |
253 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
254 | (memcmp(supported_mechs[i]->oid.elements, | |
255 | ctx->oid->elements, ctx->oid->length) == 0)) | |
256 | client->mech = supported_mechs[i]; | |
257 | i++; | |
258 | } | |
259 | ||
260 | if (client->mech == NULL) | |
261 | return GSS_S_FAILURE; | |
262 | ||
263 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
264 | &client->displayname, NULL))) { | |
265 | ssh_gssapi_error(ctx); | |
266 | return (ctx->major); | |
267 | } | |
268 | ||
269 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
270 | &ename))) { | |
271 | ssh_gssapi_error(ctx); | |
272 | return (ctx->major); | |
273 | } | |
274 | ||
275 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
276 | &client->exportedname))) { | |
277 | return (ctx->major); | |
278 | } | |
279 | ||
280 | /* We can't copy this structure, so we just move the pointer to it */ | |
281 | client->creds = ctx->client_creds; | |
282 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
283 | return (ctx->major); | |
284 | } | |
285 | ||
540d72c3 | 286 | /* As user - called on fatal/exit */ |
7cac2b65 | 287 | void |
540d72c3 | 288 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 289 | { |
290 | if (gssapi_client.store.filename != NULL) { | |
291 | /* Unlink probably isn't sufficient */ | |
292 | debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); | |
293 | unlink(gssapi_client.store.filename); | |
294 | } | |
295 | } | |
296 | ||
297 | /* As user */ | |
298 | void | |
299 | ssh_gssapi_storecreds(void) | |
300 | { | |
301 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
302 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
7cac2b65 | 303 | } else |
304 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
305 | } | |
306 | ||
307 | /* This allows GSSAPI methods to do things to the childs environment based | |
308 | * on the passed authentication process and credentials. | |
309 | */ | |
310 | /* As user */ | |
311 | void | |
312 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
313 | { | |
314 | ||
315 | if (gssapi_client.store.envvar != NULL && | |
316 | gssapi_client.store.envval != NULL) { | |
317 | ||
318 | debug("Setting %s to %s", gssapi_client.store.envvar, | |
319 | gssapi_client.store.envval); | |
320 | child_set_env(envp, envsizep, gssapi_client.store.envvar, | |
2ce0bfe4 | 321 | gssapi_client.store.envval); |
7cac2b65 | 322 | } |
323 | } | |
324 | ||
325 | /* Priviledged */ | |
326 | int | |
327 | ssh_gssapi_userok(char *user) | |
328 | { | |
2ce0bfe4 | 329 | OM_uint32 lmin; |
330 | ||
7cac2b65 | 331 | if (gssapi_client.exportedname.length == 0 || |
332 | gssapi_client.exportedname.value == NULL) { | |
333 | debug("No suitable client data"); | |
334 | return 0; | |
335 | } | |
b4cfa386 | 336 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
337 | if (limited) { | |
338 | debug("limited proxy not acceptable for remote login"); | |
339 | return 0; | |
340 | } | |
341 | #endif | |
7cac2b65 | 342 | if (gssapi_client.mech && gssapi_client.mech->userok) |
2ce0bfe4 | 343 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
344 | return 1; | |
345 | else { | |
346 | /* Destroy delegated credentials if userok fails */ | |
347 | gss_release_buffer(&lmin, &gssapi_client.displayname); | |
348 | gss_release_buffer(&lmin, &gssapi_client.exportedname); | |
349 | gss_release_cred(&lmin, &gssapi_client.creds); | |
350 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); | |
351 | return 0; | |
352 | } | |
7cac2b65 | 353 | else |
354 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
355 | return (0); | |
356 | } | |
357 | ||
e23e524c | 358 | /* Priviledged */ |
23987cb8 | 359 | int |
360 | ssh_gssapi_localname(char **user) | |
361 | { | |
362 | *user = NULL; | |
7cac2b65 | 363 | if (gssapi_client.displayname.length==0 || |
364 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 365 | debug("No suitable client data"); |
366 | return(0);; | |
367 | } | |
368 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
369 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
370 | } else { | |
371 | debug("Unknown client authentication type"); | |
372 | } | |
373 | return(0); | |
374 | } | |
540d72c3 | 375 | |
23987cb8 | 376 | #endif |