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1 | /* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */ | |
2 | ||
3 | /* | |
4 | * Copyright (c) 2001-2007 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 | #ifdef KRB5 | |
31 | ||
32 | #include <sys/types.h> | |
33 | ||
34 | #include <stdarg.h> | |
35 | #include <string.h> | |
36 | ||
37 | #include "xmalloc.h" | |
38 | #include "key.h" | |
39 | #include "hostfile.h" | |
40 | #include "auth.h" | |
41 | #include "log.h" | |
42 | #include "servconf.h" | |
43 | ||
44 | #include "buffer.h" | |
45 | #include "ssh-gss.h" | |
46 | ||
47 | extern ServerOptions options; | |
48 | ||
49 | #ifdef HEIMDAL | |
50 | # include <krb5.h> | |
51 | #elif !defined(MECHGLUE) | |
52 | # ifdef HAVE_GSSAPI_KRB5_H | |
53 | # include <gssapi_krb5.h> | |
54 | # elif HAVE_GSSAPI_GSSAPI_KRB5_H | |
55 | # include <gssapi/gssapi_krb5.h> | |
56 | # endif | |
57 | #endif | |
58 | ||
59 | static krb5_context krb_context = NULL; | |
60 | static int ssh_gssapi_krb5_init(); | |
61 | static int ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name); | |
62 | static int ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user); | |
63 | static void ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client); | |
64 | static int ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, | |
65 | ssh_gssapi_client *client); | |
66 | ||
67 | ssh_gssapi_mech gssapi_kerberos_mech = { | |
68 | "toWM5Slw5Ew8Mqkay+al2g==", | |
69 | "Kerberos", | |
70 | {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, | |
71 | NULL, | |
72 | &ssh_gssapi_krb5_userok, | |
73 | &ssh_gssapi_krb5_localname, | |
74 | &ssh_gssapi_krb5_storecreds, | |
75 | &ssh_gssapi_krb5_updatecreds | |
76 | }; | |
77 | ||
78 | /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ | |
79 | ||
80 | static int | |
81 | ssh_gssapi_krb5_init(void) | |
82 | { | |
83 | krb5_error_code problem; | |
84 | ||
85 | if (krb_context != NULL) | |
86 | return 1; | |
87 | ||
88 | problem = krb5_init_context(&krb_context); | |
89 | if (problem) { | |
90 | logit("Cannot initialize krb5 context"); | |
91 | return 0; | |
92 | } | |
93 | ||
94 | return 1; | |
95 | } | |
96 | ||
97 | /* Check if this user is OK to login. This only works with krb5 - other | |
98 | * GSSAPI mechanisms will need their own. | |
99 | * Returns true if the user is OK to log in, otherwise returns 0 | |
100 | */ | |
101 | ||
102 | static int | |
103 | ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) | |
104 | { | |
105 | krb5_principal princ; | |
106 | int retval; | |
107 | ||
108 | if (ssh_gssapi_krb5_init() == 0) | |
109 | return 0; | |
110 | ||
111 | if ((retval = krb5_parse_name(krb_context, client->exportedname.value, | |
112 | &princ))) { | |
113 | logit("krb5_parse_name(): %.100s", | |
114 | krb5_get_err_text(krb_context, retval)); | |
115 | return 0; | |
116 | } | |
117 | if (krb5_kuserok(krb_context, princ, name)) { | |
118 | retval = 1; | |
119 | logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", | |
120 | name, (char *)client->displayname.value); | |
121 | } else | |
122 | retval = 0; | |
123 | ||
124 | krb5_free_principal(krb_context, princ); | |
125 | return retval; | |
126 | } | |
127 | ||
128 | ||
129 | /* Retrieve the local username associated with a set of Kerberos | |
130 | * credentials. Hopefully we can use this for the 'empty' username | |
131 | * logins discussed in the draft */ | |
132 | static int | |
133 | ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user) { | |
134 | krb5_principal princ; | |
135 | int retval; | |
136 | ||
137 | if (ssh_gssapi_krb5_init() == 0) | |
138 | return 0; | |
139 | ||
140 | if ((retval=krb5_parse_name(krb_context, client->displayname.value, | |
141 | &princ))) { | |
142 | logit("krb5_parse_name(): %.100s", | |
143 | krb5_get_err_text(krb_context,retval)); | |
144 | return 0; | |
145 | } | |
146 | ||
147 | /* We've got to return a malloc'd string */ | |
148 | *user = (char *)xmalloc(256); | |
149 | if (krb5_aname_to_localname(krb_context, princ, 256, *user)) { | |
150 | xfree(*user); | |
151 | *user = NULL; | |
152 | return(0); | |
153 | } | |
154 | ||
155 | return(1); | |
156 | } | |
157 | ||
158 | /* This writes out any forwarded credentials from the structure populated | |
159 | * during userauth. Called after we have setuid to the user */ | |
160 | ||
161 | static void | |
162 | ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) | |
163 | { | |
164 | krb5_ccache ccache; | |
165 | krb5_error_code problem; | |
166 | krb5_principal princ; | |
167 | OM_uint32 maj_status, min_status; | |
168 | gss_cred_id_t krb5_cred_handle; | |
169 | int len; | |
170 | const char *new_ccname; | |
171 | ||
172 | if (client->creds == NULL) { | |
173 | debug("No credentials stored"); | |
174 | return; | |
175 | } | |
176 | ||
177 | if (ssh_gssapi_krb5_init() == 0) | |
178 | return; | |
179 | ||
180 | #ifdef HEIMDAL | |
181 | if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) { | |
182 | logit("krb5_cc_gen_new(): %.100s", | |
183 | krb5_get_err_text(krb_context, problem)); | |
184 | return; | |
185 | } | |
186 | #else | |
187 | if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) { | |
188 | logit("ssh_krb5_cc_gen(): %.100s", | |
189 | krb5_get_err_text(krb_context, problem)); | |
190 | return; | |
191 | } | |
192 | #endif /* #ifdef HEIMDAL */ | |
193 | ||
194 | if ((problem = krb5_parse_name(krb_context, | |
195 | client->exportedname.value, &princ))) { | |
196 | logit("krb5_parse_name(): %.100s", | |
197 | krb5_get_err_text(krb_context, problem)); | |
198 | krb5_cc_destroy(krb_context, ccache); | |
199 | return; | |
200 | } | |
201 | ||
202 | if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { | |
203 | logit("krb5_cc_initialize(): %.100s", | |
204 | krb5_get_err_text(krb_context, problem)); | |
205 | krb5_free_principal(krb_context, princ); | |
206 | krb5_cc_destroy(krb_context, ccache); | |
207 | return; | |
208 | } | |
209 | ||
210 | krb5_free_principal(krb_context, princ); | |
211 | ||
212 | #ifdef MECHGLUE | |
213 | krb5_cred_handle = | |
214 | __gss_get_mechanism_cred(client->creds, | |
215 | &(gssapi_kerberos_mech.oid)); | |
216 | #else | |
217 | krb5_cred_handle = client->creds; | |
218 | #endif | |
219 | ||
220 | if ((maj_status = gss_krb5_copy_ccache(&min_status, | |
221 | krb5_cred_handle, ccache))) { | |
222 | logit("gss_krb5_copy_ccache() failed"); | |
223 | krb5_cc_destroy(krb_context, ccache); | |
224 | return; | |
225 | } | |
226 | ||
227 | new_ccname = krb5_cc_get_name(krb_context, ccache); | |
228 | ||
229 | client->store.envvar = "KRB5CCNAME"; | |
230 | #ifdef USE_CCAPI | |
231 | xasprintf(&client->store.envval, "API:%s", new_ccname); | |
232 | client->store.filename = NULL; | |
233 | #else | |
234 | xasprintf(&client->store.envval, "FILE:%s", new_ccname); | |
235 | client->store.filename = xstrdup(new_ccname); | |
236 | #endif | |
237 | ||
238 | #ifdef USE_PAM | |
239 | if (options.use_pam) | |
240 | do_pam_putenv(client->store.envvar, client->store.envval); | |
241 | #endif | |
242 | ||
243 | krb5_cc_close(krb_context, ccache); | |
244 | ||
245 | return; | |
246 | } | |
247 | ||
248 | static int | |
249 | ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, | |
250 | ssh_gssapi_client *client) | |
251 | { | |
252 | krb5_ccache ccache = NULL; | |
253 | krb5_principal principal = NULL; | |
254 | char *name = NULL; | |
255 | krb5_error_code problem; | |
256 | OM_uint32 maj_status, min_status; | |
257 | ||
258 | if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) { | |
259 | logit("krb5_cc_resolve(): %.100s", | |
260 | krb5_get_err_text(krb_context, problem)); | |
261 | return 0; | |
262 | } | |
263 | ||
264 | /* Find out who the principal in this cache is */ | |
265 | if ((problem = krb5_cc_get_principal(krb_context, ccache, | |
266 | &principal))) { | |
267 | logit("krb5_cc_get_principal(): %.100s", | |
268 | krb5_get_err_text(krb_context, problem)); | |
269 | krb5_cc_close(krb_context, ccache); | |
270 | return 0; | |
271 | } | |
272 | ||
273 | if ((problem = krb5_unparse_name(krb_context, principal, &name))) { | |
274 | logit("krb5_unparse_name(): %.100s", | |
275 | krb5_get_err_text(krb_context, problem)); | |
276 | krb5_free_principal(krb_context, principal); | |
277 | krb5_cc_close(krb_context, ccache); | |
278 | return 0; | |
279 | } | |
280 | ||
281 | ||
282 | if (strcmp(name,client->exportedname.value)!=0) { | |
283 | debug("Name in local credentials cache differs. Not storing"); | |
284 | krb5_free_principal(krb_context, principal); | |
285 | krb5_cc_close(krb_context, ccache); | |
286 | krb5_free_unparsed_name(krb_context, name); | |
287 | return 0; | |
288 | } | |
289 | krb5_free_unparsed_name(krb_context, name); | |
290 | ||
291 | /* Name matches, so lets get on with it! */ | |
292 | ||
293 | if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) { | |
294 | logit("krb5_cc_initialize(): %.100s", | |
295 | krb5_get_err_text(krb_context, problem)); | |
296 | krb5_free_principal(krb_context, principal); | |
297 | krb5_cc_close(krb_context, ccache); | |
298 | return 0; | |
299 | } | |
300 | ||
301 | krb5_free_principal(krb_context, principal); | |
302 | ||
303 | if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds, | |
304 | ccache))) { | |
305 | logit("gss_krb5_copy_ccache() failed. Sorry!"); | |
306 | krb5_cc_close(krb_context, ccache); | |
307 | return 0; | |
308 | } | |
309 | ||
310 | return 1; | |
311 | } | |
312 | ||
313 | #endif /* KRB5 */ | |
314 | ||
315 | #endif /* GSSAPI */ |