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1 | /* $OpenBSD: gss-serv-krb5.c,v 1.1 2003/08/22 10:56:09 markus Exp $ */ | |
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 | #ifdef KRB5 | |
31 | ||
32 | #include "auth.h" | |
33 | #include "xmalloc.h" | |
34 | #include "log.h" | |
35 | #include "servconf.h" | |
36 | ||
37 | #include "ssh-gss.h" | |
38 | ||
39 | extern ServerOptions options; | |
40 | ||
41 | #ifdef HEIMDAL | |
42 | #include <krb5.h> | |
43 | #else | |
44 | #include <gssapi_krb5.h> | |
45 | #endif | |
46 | ||
47 | static krb5_context krb_context = NULL; | |
48 | ||
49 | /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ | |
50 | ||
51 | static int | |
52 | ssh_gssapi_krb5_init() | |
53 | { | |
54 | krb5_error_code problem; | |
55 | ||
56 | if (krb_context != NULL) | |
57 | return 1; | |
58 | ||
59 | problem = krb5_init_context(&krb_context); | |
60 | if (problem) { | |
61 | logit("Cannot initialize krb5 context"); | |
62 | return 0; | |
63 | } | |
64 | krb5_init_ets(krb_context); | |
65 | ||
66 | return 1; | |
67 | } | |
68 | ||
69 | /* Check if this user is OK to login. This only works with krb5 - other | |
70 | * GSSAPI mechanisms will need their own. | |
71 | * Returns true if the user is OK to log in, otherwise returns 0 | |
72 | */ | |
73 | ||
74 | static int | |
75 | ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) | |
76 | { | |
77 | krb5_principal princ; | |
78 | int retval; | |
79 | ||
80 | if (ssh_gssapi_krb5_init() == 0) | |
81 | return 0; | |
82 | ||
83 | if ((retval = krb5_parse_name(krb_context, client->exportedname.value, | |
84 | &princ))) { | |
85 | logit("krb5_parse_name(): %.100s", | |
86 | krb5_get_err_text(krb_context, retval)); | |
87 | return 0; | |
88 | } | |
89 | if (krb5_kuserok(krb_context, princ, name)) { | |
90 | retval = 1; | |
91 | logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", | |
92 | name, (char *)client->displayname.value); | |
93 | } else | |
94 | retval = 0; | |
95 | ||
96 | krb5_free_principal(krb_context, princ); | |
97 | return retval; | |
98 | } | |
99 | ||
100 | ||
101 | /* Retrieve the local username associated with a set of Kerberos | |
102 | * credentials. Hopefully we can use this for the 'empty' username | |
103 | * logins discussed in the draft */ | |
104 | static int | |
105 | ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user) { | |
106 | krb5_principal princ; | |
107 | int retval; | |
108 | ||
109 | if (ssh_gssapi_krb5_init() == 0) | |
110 | return 0; | |
111 | ||
112 | if ((retval=krb5_parse_name(krb_context, client->displayname.value, | |
113 | &princ))) { | |
114 | logit("krb5_parse_name(): %.100s", | |
115 | krb5_get_err_text(krb_context,retval)); | |
116 | return 0; | |
117 | } | |
118 | ||
119 | /* We've got to return a malloc'd string */ | |
120 | *user = (char *)xmalloc(256); | |
121 | if (krb5_aname_to_localname(krb_context, princ, 256, *user)) { | |
122 | xfree(*user); | |
123 | *user = NULL; | |
124 | return(0); | |
125 | } | |
126 | ||
127 | return(1); | |
128 | } | |
129 | ||
130 | /* This writes out any forwarded credentials from the structure populated | |
131 | * during userauth. Called after we have setuid to the user */ | |
132 | ||
133 | static void | |
134 | ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) | |
135 | { | |
136 | krb5_ccache ccache; | |
137 | krb5_error_code problem; | |
138 | krb5_principal princ; | |
139 | OM_uint32 maj_status, min_status; | |
140 | gss_cred_id_t krb5_cred_handle; | |
141 | ||
142 | ||
143 | if (client->creds == NULL) { | |
144 | debug("No credentials stored"); | |
145 | return; | |
146 | } | |
147 | ||
148 | if (ssh_gssapi_krb5_init() == 0) | |
149 | return; | |
150 | ||
151 | #ifdef HEIMDAL | |
152 | if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) { | |
153 | logit("krb5_cc_gen_new(): %.100s", | |
154 | krb5_get_err_text(krb_context, problem)); | |
155 | return; | |
156 | } | |
157 | #else | |
158 | { | |
159 | int tmpfd; | |
160 | char ccname[40]; | |
161 | ||
162 | snprintf(ccname, sizeof(ccname), | |
163 | "FILE:/tmp/krb5cc_%d_XXXXXX", geteuid()); | |
164 | ||
165 | if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -1) { | |
166 | logit("mkstemp(): %.100s", strerror(errno)); | |
167 | problem = errno; | |
168 | return; | |
169 | } | |
170 | if (fchmod(tmpfd, S_IRUSR | S_IWUSR) == -1) { | |
171 | logit("fchmod(): %.100s", strerror(errno)); | |
172 | close(tmpfd); | |
173 | problem = errno; | |
174 | return; | |
175 | } | |
176 | close(tmpfd); | |
177 | if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) { | |
178 | logit("krb5_cc_resolve(): %.100s", | |
179 | krb5_get_err_text(krb_context, problem)); | |
180 | return; | |
181 | } | |
182 | } | |
183 | #endif /* #ifdef HEIMDAL */ | |
184 | ||
185 | if ((problem = krb5_parse_name(krb_context, | |
186 | client->exportedname.value, &princ))) { | |
187 | logit("krb5_parse_name(): %.100s", | |
188 | krb5_get_err_text(krb_context, problem)); | |
189 | krb5_cc_destroy(krb_context, ccache); | |
190 | return; | |
191 | } | |
192 | ||
193 | if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { | |
194 | logit("krb5_cc_initialize(): %.100s", | |
195 | krb5_get_err_text(krb_context, problem)); | |
196 | krb5_free_principal(krb_context, princ); | |
197 | krb5_cc_destroy(krb_context, ccache); | |
198 | return; | |
199 | } | |
200 | ||
201 | krb5_free_principal(krb_context, princ); | |
202 | ||
203 | #ifdef MECHGLUE | |
204 | krb5_cred_handle = | |
205 | __gss_get_mechanism_cred(client->creds, | |
206 | &(gssapi_kerberos_mech.oid)); | |
207 | #else | |
208 | krb5_cred_handle = client->creds; | |
209 | #endif | |
210 | ||
211 | if ((maj_status = gss_krb5_copy_ccache(&min_status, | |
212 | krb5_cred_handle, ccache))) { | |
213 | logit("gss_krb5_copy_ccache() failed"); | |
214 | krb5_cc_destroy(krb_context, ccache); | |
215 | return; | |
216 | } | |
217 | ||
218 | client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache)); | |
219 | client->store.envvar = "KRB5CCNAME"; | |
220 | client->store.envval = xstrdup(client->store.filename); | |
221 | ||
222 | #ifdef USE_PAM | |
223 | if (options.use_pam) | |
224 | do_pam_putenv(client->store.envvar,client->store.envval); | |
225 | #endif | |
226 | ||
227 | krb5_cc_close(krb_context, ccache); | |
228 | ||
229 | return; | |
230 | } | |
231 | ||
232 | ssh_gssapi_mech gssapi_kerberos_mech = { | |
233 | "toWM5Slw5Ew8Mqkay+al2g==", | |
234 | "Kerberos", | |
235 | {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, | |
236 | NULL, | |
237 | &ssh_gssapi_krb5_userok, | |
238 | &ssh_gssapi_krb5_localname, | |
239 | &ssh_gssapi_krb5_storecreds | |
240 | }; | |
241 | ||
242 | ssh_gssapi_mech gssapi_kerberos_mech_old = { | |
243 | "Se3H81ismmOC3OE+FwYCiQ==", | |
244 | "Kerberos", | |
245 | {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, | |
246 | &ssh_gssapi_krb5_init, | |
247 | &ssh_gssapi_krb5_userok, | |
248 | &ssh_gssapi_krb5_localname, | |
249 | &ssh_gssapi_krb5_storecreds | |
250 | }; | |
251 | ||
252 | #endif /* KRB5 */ | |
253 | ||
254 | #endif /* GSSAPI */ |