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d4487008 | 1 | /* $OpenBSD: gss-serv.c,v 1.21 2007/06/12 08:20:00 djm Exp $ */ |
0fff78ff | 2 | |
3 | /* | |
4 | * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. | |
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 | ||
9108f8d9 | 31 | #include <sys/types.h> |
d4487008 | 32 | #include <sys/param.h> |
9108f8d9 | 33 | |
34 | #include <stdarg.h> | |
35 | #include <string.h> | |
36 | #include <unistd.h> | |
37 | ||
38 | #include "xmalloc.h" | |
39 | #include "buffer.h" | |
40 | #include "key.h" | |
41 | #include "hostfile.h" | |
0fff78ff | 42 | #include "auth.h" |
43 | #include "log.h" | |
44 | #include "channels.h" | |
45 | #include "session.h" | |
9108f8d9 | 46 | #include "misc.h" |
0fff78ff | 47 | |
48 | #include "ssh-gss.h" | |
49 | ||
0fff78ff | 50 | static ssh_gssapi_client gssapi_client = |
51 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, | |
52 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
53 | ||
54 | ssh_gssapi_mech gssapi_null_mech = | |
55 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
56 | ||
57 | #ifdef KRB5 | |
58 | extern ssh_gssapi_mech gssapi_kerberos_mech; | |
59 | #endif | |
60 | ||
61 | ssh_gssapi_mech* supported_mechs[]= { | |
62 | #ifdef KRB5 | |
63 | &gssapi_kerberos_mech, | |
64 | #endif | |
65 | &gssapi_null_mech, | |
66 | }; | |
67 | ||
d4487008 | 68 | |
69 | /* | |
70 | * Acquire credentials for a server running on the current host. | |
71 | * Requires that the context structure contains a valid OID | |
72 | */ | |
73 | ||
74 | /* Returns a GSSAPI error code */ | |
75 | /* Privileged (called from ssh_gssapi_server_ctx) */ | |
76 | static OM_uint32 | |
77 | ssh_gssapi_acquire_cred(Gssctxt *ctx) | |
78 | { | |
79 | OM_uint32 status; | |
80 | char lname[MAXHOSTNAMELEN]; | |
81 | gss_OID_set oidset; | |
82 | ||
83 | gss_create_empty_oid_set(&status, &oidset); | |
84 | gss_add_oid_set_member(&status, ctx->oid, &oidset); | |
85 | ||
86 | if (gethostname(lname, MAXHOSTNAMELEN)) { | |
87 | gss_release_oid_set(&status, &oidset); | |
88 | return (-1); | |
89 | } | |
90 | ||
91 | if (GSS_ERROR(ssh_gssapi_import_name(ctx, lname))) { | |
92 | gss_release_oid_set(&status, &oidset); | |
93 | return (ctx->major); | |
94 | } | |
95 | ||
96 | if ((ctx->major = gss_acquire_cred(&ctx->minor, | |
97 | ctx->name, 0, oidset, GSS_C_ACCEPT, &ctx->creds, NULL, NULL))) | |
98 | ssh_gssapi_error(ctx); | |
99 | ||
100 | gss_release_oid_set(&status, &oidset); | |
101 | return (ctx->major); | |
102 | } | |
103 | ||
104 | /* Privileged */ | |
105 | OM_uint32 | |
106 | ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID oid) | |
107 | { | |
108 | if (*ctx) | |
109 | ssh_gssapi_delete_ctx(ctx); | |
110 | ssh_gssapi_build_ctx(ctx); | |
111 | ssh_gssapi_set_oid(*ctx, oid); | |
112 | return (ssh_gssapi_acquire_cred(*ctx)); | |
113 | } | |
114 | ||
2c06c99b | 115 | /* Unprivileged */ |
0fff78ff | 116 | void |
117 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
118 | { | |
119 | int i = 0; | |
120 | OM_uint32 min_status; | |
121 | int present; | |
122 | gss_OID_set supported; | |
123 | ||
124 | gss_create_empty_oid_set(&min_status, oidset); | |
125 | gss_indicate_mechs(&min_status, &supported); | |
126 | ||
127 | while (supported_mechs[i]->name != NULL) { | |
128 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
129 | &supported_mechs[i]->oid, supported, &present))) | |
130 | present = 0; | |
131 | if (present) | |
132 | gss_add_oid_set_member(&min_status, | |
133 | &supported_mechs[i]->oid, oidset); | |
134 | i++; | |
135 | } | |
9108f8d9 | 136 | |
137 | gss_release_oid_set(&min_status, &supported); | |
0fff78ff | 138 | } |
139 | ||
140 | ||
141 | /* Wrapper around accept_sec_context | |
142 | * Requires that the context contains: | |
143 | * oid | |
144 | * credentials (from ssh_gssapi_acquire_cred) | |
145 | */ | |
2c06c99b | 146 | /* Privileged */ |
0fff78ff | 147 | OM_uint32 |
148 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
149 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
150 | { | |
151 | OM_uint32 status; | |
152 | gss_OID mech; | |
153 | ||
154 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
155 | &ctx->context, ctx->creds, recv_tok, | |
156 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
157 | send_tok, flags, NULL, &ctx->client_creds); | |
158 | ||
159 | if (GSS_ERROR(ctx->major)) | |
160 | ssh_gssapi_error(ctx); | |
161 | ||
162 | if (ctx->client_creds) | |
163 | debug("Received some client credentials"); | |
164 | else | |
165 | debug("Got no client credentials"); | |
166 | ||
167 | status = ctx->major; | |
168 | ||
169 | /* Now, if we're complete and we have the right flags, then | |
170 | * we flag the user as also having been authenticated | |
171 | */ | |
172 | ||
173 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
174 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
175 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
176 | fatal("Couldn't convert client name"); | |
177 | } | |
178 | ||
179 | return (status); | |
180 | } | |
181 | ||
182 | /* | |
183 | * This parses an exported name, extracting the mechanism specific portion | |
184 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
185 | * originally selected. | |
186 | */ | |
187 | static OM_uint32 | |
188 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
189 | { | |
665a873d | 190 | u_char *tok; |
0fff78ff | 191 | OM_uint32 offset; |
192 | OM_uint32 oidl; | |
193 | ||
2c06c99b | 194 | tok = ename->value; |
0fff78ff | 195 | |
196 | /* | |
197 | * Check that ename is long enough for all of the fixed length | |
198 | * header, and that the initial ID bytes are correct | |
199 | */ | |
200 | ||
2c06c99b | 201 | if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
0fff78ff | 202 | return GSS_S_FAILURE; |
203 | ||
204 | /* | |
205 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
206 | * and does use the OID type and length bytes. To confuse things | |
207 | * there are two lengths - the first including these, and the | |
208 | * second without. | |
209 | */ | |
210 | ||
9108f8d9 | 211 | oidl = get_u16(tok+2); /* length including next two bytes */ |
0fff78ff | 212 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ |
213 | ||
214 | /* | |
215 | * Check the BER encoding for correct type and length, that the | |
216 | * string is long enough and that the OID matches that in our context | |
217 | */ | |
218 | if (tok[4] != 0x06 || tok[5] != oidl || | |
219 | ename->length < oidl+6 || | |
2c06c99b | 220 | !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
0fff78ff | 221 | return GSS_S_FAILURE; |
222 | ||
223 | offset = oidl+6; | |
224 | ||
225 | if (ename->length < offset+4) | |
226 | return GSS_S_FAILURE; | |
227 | ||
9108f8d9 | 228 | name->length = get_u32(tok+offset); |
0fff78ff | 229 | offset += 4; |
230 | ||
231 | if (ename->length < offset+name->length) | |
232 | return GSS_S_FAILURE; | |
233 | ||
234 | name->value = xmalloc(name->length+1); | |
9108f8d9 | 235 | memcpy(name->value, tok+offset, name->length); |
0fff78ff | 236 | ((char *)name->value)[name->length] = 0; |
237 | ||
238 | return GSS_S_COMPLETE; | |
239 | } | |
240 | ||
241 | /* Extract the client details from a given context. This can only reliably | |
242 | * be called once for a context */ | |
243 | ||
2c06c99b | 244 | /* Privileged (called from accept_secure_ctx) */ |
0fff78ff | 245 | OM_uint32 |
246 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
247 | { | |
248 | int i = 0; | |
249 | ||
250 | gss_buffer_desc ename; | |
251 | ||
252 | client->mech = NULL; | |
253 | ||
254 | while (supported_mechs[i]->name != NULL) { | |
255 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
256 | (memcmp(supported_mechs[i]->oid.elements, | |
257 | ctx->oid->elements, ctx->oid->length) == 0)) | |
258 | client->mech = supported_mechs[i]; | |
259 | i++; | |
260 | } | |
261 | ||
262 | if (client->mech == NULL) | |
263 | return GSS_S_FAILURE; | |
264 | ||
265 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
266 | &client->displayname, NULL))) { | |
267 | ssh_gssapi_error(ctx); | |
268 | return (ctx->major); | |
269 | } | |
270 | ||
271 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
272 | &ename))) { | |
273 | ssh_gssapi_error(ctx); | |
274 | return (ctx->major); | |
275 | } | |
276 | ||
277 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
278 | &client->exportedname))) { | |
279 | return (ctx->major); | |
280 | } | |
281 | ||
282 | /* We can't copy this structure, so we just move the pointer to it */ | |
283 | client->creds = ctx->client_creds; | |
284 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
285 | return (ctx->major); | |
286 | } | |
287 | ||
cdd66111 | 288 | /* As user - called on fatal/exit */ |
0fff78ff | 289 | void |
cdd66111 | 290 | ssh_gssapi_cleanup_creds(void) |
0fff78ff | 291 | { |
292 | if (gssapi_client.store.filename != NULL) { | |
293 | /* Unlink probably isn't sufficient */ | |
9108f8d9 | 294 | debug("removing gssapi cred file\"%s\"", |
295 | gssapi_client.store.filename); | |
0fff78ff | 296 | unlink(gssapi_client.store.filename); |
297 | } | |
298 | } | |
299 | ||
300 | /* As user */ | |
301 | void | |
302 | ssh_gssapi_storecreds(void) | |
303 | { | |
304 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
305 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
0fff78ff | 306 | } else |
307 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
308 | } | |
309 | ||
310 | /* This allows GSSAPI methods to do things to the childs environment based | |
311 | * on the passed authentication process and credentials. | |
312 | */ | |
313 | /* As user */ | |
314 | void | |
315 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
316 | { | |
317 | ||
318 | if (gssapi_client.store.envvar != NULL && | |
319 | gssapi_client.store.envval != NULL) { | |
0fff78ff | 320 | debug("Setting %s to %s", gssapi_client.store.envvar, |
2c06c99b | 321 | gssapi_client.store.envval); |
0fff78ff | 322 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
665a873d | 323 | gssapi_client.store.envval); |
0fff78ff | 324 | } |
325 | } | |
326 | ||
2c06c99b | 327 | /* Privileged */ |
0fff78ff | 328 | int |
329 | ssh_gssapi_userok(char *user) | |
330 | { | |
665a873d | 331 | OM_uint32 lmin; |
332 | ||
0fff78ff | 333 | if (gssapi_client.exportedname.length == 0 || |
334 | gssapi_client.exportedname.value == NULL) { | |
335 | debug("No suitable client data"); | |
336 | return 0; | |
337 | } | |
338 | if (gssapi_client.mech && gssapi_client.mech->userok) | |
665a873d | 339 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
340 | return 1; | |
341 | else { | |
342 | /* Destroy delegated credentials if userok fails */ | |
343 | gss_release_buffer(&lmin, &gssapi_client.displayname); | |
344 | gss_release_buffer(&lmin, &gssapi_client.exportedname); | |
345 | gss_release_cred(&lmin, &gssapi_client.creds); | |
346 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); | |
347 | return 0; | |
348 | } | |
0fff78ff | 349 | else |
350 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
351 | return (0); | |
352 | } | |
353 | ||
2c06c99b | 354 | /* Privileged */ |
cdd66111 | 355 | OM_uint32 |
356 | ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic) | |
357 | { | |
358 | ctx->major = gss_verify_mic(&ctx->minor, ctx->context, | |
359 | gssbuf, gssmic, NULL); | |
360 | ||
361 | return (ctx->major); | |
362 | } | |
363 | ||
0fff78ff | 364 | #endif |