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08822d99 | 1 | /* $OpenBSD: gss-serv.c,v 1.13 2005/10/13 22:24:31 stevesk 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 | ||
23987cb8 | 47 | static ssh_gssapi_client gssapi_client = |
7cac2b65 | 48 | { GSS_C_EMPTY_BUFFER, GSS_C_EMPTY_BUFFER, |
49 | GSS_C_NO_CREDENTIAL, NULL, {NULL, NULL, NULL}}; | |
5598e598 | 50 | |
7cac2b65 | 51 | ssh_gssapi_mech gssapi_null_mech = |
52 | { NULL, NULL, {0, NULL}, NULL, NULL, NULL, NULL}; | |
44a053a3 | 53 | |
5598e598 | 54 | #ifdef KRB5 |
23987cb8 | 55 | extern ssh_gssapi_mech gssapi_kerberos_mech; |
54425c7a | 56 | #endif |
5598e598 | 57 | #ifdef GSI |
23987cb8 | 58 | extern ssh_gssapi_mech gssapi_gsi_mech; |
b311f64e | 59 | #endif |
60 | ||
23987cb8 | 61 | ssh_gssapi_mech* supported_mechs[]= { |
5598e598 | 62 | #ifdef KRB5 |
7cac2b65 | 63 | &gssapi_kerberos_mech, |
5598e598 | 64 | #endif |
65 | #ifdef GSI | |
7cac2b65 | 66 | &gssapi_gsi_mech, |
7b5a625b | 67 | #endif |
7cac2b65 | 68 | &gssapi_null_mech, |
23987cb8 | 69 | }; |
5598e598 | 70 | |
b4cfa386 | 71 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
72 | static int limited = 0; | |
73 | #endif | |
74 | ||
fe4ad273 | 75 | /* Unpriviledged */ |
76 | char * | |
77 | ssh_gssapi_server_mechanisms() { | |
78 | gss_OID_set supported; | |
79 | ||
80 | ssh_gssapi_supported_oids(&supported); | |
81 | return (ssh_gssapi_kex_mechs(supported, &ssh_gssapi_server_check_mech, | |
82 | NULL)); | |
83 | } | |
84 | ||
85 | /* Unpriviledged */ | |
86 | int | |
87 | ssh_gssapi_server_check_mech(gss_OID oid, void *data) { | |
88 | Gssctxt * ctx = NULL; | |
89 | int res; | |
90 | ||
91 | res = !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx, oid))); | |
92 | ssh_gssapi_delete_ctx(&ctx); | |
93 | ||
94 | return (res); | |
95 | } | |
96 | ||
7cac2b65 | 97 | /* Unpriviledged */ |
98 | void | |
99 | ssh_gssapi_supported_oids(gss_OID_set *oidset) | |
100 | { | |
101 | int i = 0; | |
102 | OM_uint32 min_status; | |
103 | int present; | |
104 | gss_OID_set supported; | |
105 | ||
106 | gss_create_empty_oid_set(&min_status, oidset); | |
186e1568 | 107 | /* Ask priviledged process what mechanisms it supports. */ |
108 | PRIVSEP(gss_indicate_mechs(&min_status, &supported)); | |
7cac2b65 | 109 | |
110 | while (supported_mechs[i]->name != NULL) { | |
111 | if (GSS_ERROR(gss_test_oid_set_member(&min_status, | |
112 | &supported_mechs[i]->oid, supported, &present))) | |
113 | present = 0; | |
114 | if (present) | |
115 | gss_add_oid_set_member(&min_status, | |
116 | &supported_mechs[i]->oid, oidset); | |
117 | i++; | |
118 | } | |
119 | } | |
120 | ||
121 | ||
122 | /* Wrapper around accept_sec_context | |
123 | * Requires that the context contains: | |
124 | * oid | |
125 | * credentials (from ssh_gssapi_acquire_cred) | |
126 | */ | |
08822d99 | 127 | /* Privileged */ |
7cac2b65 | 128 | OM_uint32 |
129 | ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *recv_tok, | |
130 | gss_buffer_desc *send_tok, OM_uint32 *flags) | |
131 | { | |
132 | OM_uint32 status; | |
133 | gss_OID mech; | |
134 | ||
135 | ctx->major = gss_accept_sec_context(&ctx->minor, | |
136 | &ctx->context, ctx->creds, recv_tok, | |
137 | GSS_C_NO_CHANNEL_BINDINGS, &ctx->client, &mech, | |
138 | send_tok, flags, NULL, &ctx->client_creds); | |
139 | ||
140 | if (GSS_ERROR(ctx->major)) | |
141 | ssh_gssapi_error(ctx); | |
142 | ||
143 | if (ctx->client_creds) | |
144 | debug("Received some client credentials"); | |
145 | else | |
146 | debug("Got no client credentials"); | |
147 | ||
148 | status = ctx->major; | |
149 | ||
150 | /* Now, if we're complete and we have the right flags, then | |
151 | * we flag the user as also having been authenticated | |
152 | */ | |
153 | ||
154 | if (((flags == NULL) || ((*flags & GSS_C_MUTUAL_FLAG) && | |
155 | (*flags & GSS_C_INTEG_FLAG))) && (ctx->major == GSS_S_COMPLETE)) { | |
156 | if (ssh_gssapi_getclient(ctx, &gssapi_client)) | |
157 | fatal("Couldn't convert client name"); | |
b4cfa386 | 158 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
159 | if (flags && (*flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG)) | |
160 | limited=1; | |
161 | #endif | |
7cac2b65 | 162 | } |
163 | ||
164 | return (status); | |
165 | } | |
166 | ||
167 | /* | |
168 | * This parses an exported name, extracting the mechanism specific portion | |
169 | * to use for ACL checking. It verifies that the name belongs the mechanism | |
170 | * originally selected. | |
171 | */ | |
172 | static OM_uint32 | |
173 | ssh_gssapi_parse_ename(Gssctxt *ctx, gss_buffer_t ename, gss_buffer_t name) | |
174 | { | |
2ce0bfe4 | 175 | u_char *tok; |
7cac2b65 | 176 | OM_uint32 offset; |
177 | OM_uint32 oidl; | |
178 | ||
08822d99 | 179 | tok = ename->value; |
7cac2b65 | 180 | |
181 | #ifdef GSI /* GSI gss_export_name() is broken. */ | |
182 | if ((ctx->oid->length == gssapi_gsi_mech.oid.length) && | |
183 | (memcmp(ctx->oid->elements, gssapi_gsi_mech.oid.elements, | |
184 | gssapi_gsi_mech.oid.length) == 0)) { | |
185 | name->length = ename->length; | |
186 | name->value = xmalloc(ename->length+1); | |
187 | memcpy(name->value, ename->value, ename->length); | |
188 | return GSS_S_COMPLETE; | |
189 | } | |
190 | #endif | |
191 | ||
192 | /* | |
193 | * Check that ename is long enough for all of the fixed length | |
194 | * header, and that the initial ID bytes are correct | |
195 | */ | |
196 | ||
08822d99 | 197 | if (ename->length < 6 || memcmp(tok, "\x04\x01", 2) != 0) |
7cac2b65 | 198 | return GSS_S_FAILURE; |
199 | ||
200 | /* | |
201 | * Extract the OID, and check it. Here GSSAPI breaks with tradition | |
202 | * and does use the OID type and length bytes. To confuse things | |
203 | * there are two lengths - the first including these, and the | |
204 | * second without. | |
205 | */ | |
206 | ||
207 | oidl = GET_16BIT(tok+2); /* length including next two bytes */ | |
208 | oidl = oidl-2; /* turn it into the _real_ length of the variable OID */ | |
209 | ||
210 | /* | |
211 | * Check the BER encoding for correct type and length, that the | |
212 | * string is long enough and that the OID matches that in our context | |
213 | */ | |
214 | if (tok[4] != 0x06 || tok[5] != oidl || | |
215 | ename->length < oidl+6 || | |
08822d99 | 216 | !ssh_gssapi_check_oid(ctx, tok+6, oidl)) |
7cac2b65 | 217 | return GSS_S_FAILURE; |
218 | ||
219 | offset = oidl+6; | |
220 | ||
221 | if (ename->length < offset+4) | |
222 | return GSS_S_FAILURE; | |
223 | ||
224 | name->length = GET_32BIT(tok+offset); | |
225 | offset += 4; | |
226 | ||
227 | if (ename->length < offset+name->length) | |
228 | return GSS_S_FAILURE; | |
229 | ||
230 | name->value = xmalloc(name->length+1); | |
08822d99 | 231 | memcpy(name->value, tok+offset,name->length); |
7cac2b65 | 232 | ((char *)name->value)[name->length] = 0; |
233 | ||
234 | return GSS_S_COMPLETE; | |
235 | } | |
236 | ||
237 | /* Extract the client details from a given context. This can only reliably | |
238 | * be called once for a context */ | |
239 | ||
08822d99 | 240 | /* Privileged (called from accept_secure_ctx) */ |
7cac2b65 | 241 | OM_uint32 |
242 | ssh_gssapi_getclient(Gssctxt *ctx, ssh_gssapi_client *client) | |
243 | { | |
244 | int i = 0; | |
245 | ||
246 | gss_buffer_desc ename; | |
247 | ||
248 | client->mech = NULL; | |
249 | ||
250 | while (supported_mechs[i]->name != NULL) { | |
251 | if (supported_mechs[i]->oid.length == ctx->oid->length && | |
252 | (memcmp(supported_mechs[i]->oid.elements, | |
253 | ctx->oid->elements, ctx->oid->length) == 0)) | |
254 | client->mech = supported_mechs[i]; | |
255 | i++; | |
256 | } | |
257 | ||
258 | if (client->mech == NULL) | |
259 | return GSS_S_FAILURE; | |
260 | ||
261 | if ((ctx->major = gss_display_name(&ctx->minor, ctx->client, | |
262 | &client->displayname, NULL))) { | |
263 | ssh_gssapi_error(ctx); | |
264 | return (ctx->major); | |
265 | } | |
266 | ||
267 | if ((ctx->major = gss_export_name(&ctx->minor, ctx->client, | |
268 | &ename))) { | |
269 | ssh_gssapi_error(ctx); | |
270 | return (ctx->major); | |
271 | } | |
272 | ||
273 | if ((ctx->major = ssh_gssapi_parse_ename(ctx,&ename, | |
274 | &client->exportedname))) { | |
275 | return (ctx->major); | |
276 | } | |
277 | ||
278 | /* We can't copy this structure, so we just move the pointer to it */ | |
279 | client->creds = ctx->client_creds; | |
280 | ctx->client_creds = GSS_C_NO_CREDENTIAL; | |
281 | return (ctx->major); | |
282 | } | |
283 | ||
540d72c3 | 284 | /* As user - called on fatal/exit */ |
7cac2b65 | 285 | void |
540d72c3 | 286 | ssh_gssapi_cleanup_creds(void) |
7cac2b65 | 287 | { |
288 | if (gssapi_client.store.filename != NULL) { | |
289 | /* Unlink probably isn't sufficient */ | |
290 | debug("removing gssapi cred file\"%s\"", gssapi_client.store.filename); | |
291 | unlink(gssapi_client.store.filename); | |
292 | } | |
293 | } | |
294 | ||
295 | /* As user */ | |
296 | void | |
297 | ssh_gssapi_storecreds(void) | |
298 | { | |
299 | if (gssapi_client.mech && gssapi_client.mech->storecreds) { | |
300 | (*gssapi_client.mech->storecreds)(&gssapi_client); | |
7cac2b65 | 301 | } else |
302 | debug("ssh_gssapi_storecreds: Not a GSSAPI mechanism"); | |
303 | } | |
304 | ||
305 | /* This allows GSSAPI methods to do things to the childs environment based | |
306 | * on the passed authentication process and credentials. | |
307 | */ | |
308 | /* As user */ | |
309 | void | |
310 | ssh_gssapi_do_child(char ***envp, u_int *envsizep) | |
311 | { | |
312 | ||
313 | if (gssapi_client.store.envvar != NULL && | |
314 | gssapi_client.store.envval != NULL) { | |
7cac2b65 | 315 | debug("Setting %s to %s", gssapi_client.store.envvar, |
08822d99 | 316 | gssapi_client.store.envval); |
7cac2b65 | 317 | child_set_env(envp, envsizep, gssapi_client.store.envvar, |
2ce0bfe4 | 318 | gssapi_client.store.envval); |
7cac2b65 | 319 | } |
320 | } | |
321 | ||
08822d99 | 322 | /* Privileged */ |
7cac2b65 | 323 | int |
324 | ssh_gssapi_userok(char *user) | |
325 | { | |
2ce0bfe4 | 326 | OM_uint32 lmin; |
327 | ||
7cac2b65 | 328 | if (gssapi_client.exportedname.length == 0 || |
329 | gssapi_client.exportedname.value == NULL) { | |
330 | debug("No suitable client data"); | |
331 | return 0; | |
332 | } | |
b4cfa386 | 333 | #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG |
334 | if (limited) { | |
335 | debug("limited proxy not acceptable for remote login"); | |
336 | return 0; | |
337 | } | |
338 | #endif | |
7cac2b65 | 339 | if (gssapi_client.mech && gssapi_client.mech->userok) |
2ce0bfe4 | 340 | if ((*gssapi_client.mech->userok)(&gssapi_client, user)) |
341 | return 1; | |
342 | else { | |
343 | /* Destroy delegated credentials if userok fails */ | |
344 | gss_release_buffer(&lmin, &gssapi_client.displayname); | |
345 | gss_release_buffer(&lmin, &gssapi_client.exportedname); | |
346 | gss_release_cred(&lmin, &gssapi_client.creds); | |
347 | memset(&gssapi_client, 0, sizeof(ssh_gssapi_client)); | |
348 | return 0; | |
349 | } | |
7cac2b65 | 350 | else |
351 | debug("ssh_gssapi_userok: Unknown GSSAPI mechanism"); | |
352 | return (0); | |
353 | } | |
354 | ||
e23e524c | 355 | /* Priviledged */ |
23987cb8 | 356 | int |
357 | ssh_gssapi_localname(char **user) | |
358 | { | |
359 | *user = NULL; | |
7cac2b65 | 360 | if (gssapi_client.displayname.length==0 || |
361 | gssapi_client.displayname.value==NULL) { | |
23987cb8 | 362 | debug("No suitable client data"); |
363 | return(0);; | |
364 | } | |
365 | if (gssapi_client.mech && gssapi_client.mech->localname) { | |
366 | return((*gssapi_client.mech->localname)(&gssapi_client,user)); | |
367 | } else { | |
368 | debug("Unknown client authentication type"); | |
369 | } | |
370 | return(0); | |
371 | } | |
540d72c3 | 372 | |
23987cb8 | 373 | #endif |