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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) 2001-2003 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 <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 | ||
65 | ssh_gssapi_mech gssapi_kerberos_mech = { | |
66 | "toWM5Slw5Ew8Mqkay+al2g==", | |
67 | "Kerberos", | |
68 | {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}, | |
69 | NULL, | |
70 | &ssh_gssapi_krb5_userok, | |
71 | &ssh_gssapi_krb5_localname, | |
72 | &ssh_gssapi_krb5_storecreds | |
73 | }; | |
74 | ||
75 | /* Initialise the krb5 library, for the stuff that GSSAPI won't do */ | |
76 | ||
77 | static int | |
78 | ssh_gssapi_krb5_init(void) | |
79 | { | |
80 | krb5_error_code problem; | |
81 | ||
82 | if (krb_context != NULL) | |
83 | return 1; | |
84 | ||
85 | problem = krb5_init_context(&krb_context); | |
86 | if (problem) { | |
87 | logit("Cannot initialize krb5 context"); | |
88 | return 0; | |
89 | } | |
90 | ||
91 | return 1; | |
92 | } | |
93 | ||
94 | /* Check if this user is OK to login. This only works with krb5 - other | |
95 | * GSSAPI mechanisms will need their own. | |
96 | * Returns true if the user is OK to log in, otherwise returns 0 | |
97 | */ | |
98 | ||
99 | static int | |
100 | ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name) | |
101 | { | |
102 | krb5_principal princ; | |
103 | int retval; | |
104 | ||
105 | if (ssh_gssapi_krb5_init() == 0) | |
106 | return 0; | |
107 | ||
108 | if ((retval = krb5_parse_name(krb_context, client->exportedname.value, | |
109 | &princ))) { | |
110 | logit("krb5_parse_name(): %.100s", | |
111 | krb5_get_err_text(krb_context, retval)); | |
112 | return 0; | |
113 | } | |
114 | if (krb5_kuserok(krb_context, princ, name)) { | |
115 | retval = 1; | |
116 | logit("Authorized to %s, krb5 principal %s (krb5_kuserok)", | |
117 | name, (char *)client->displayname.value); | |
118 | } else | |
119 | retval = 0; | |
120 | ||
121 | krb5_free_principal(krb_context, princ); | |
122 | return retval; | |
123 | } | |
124 | ||
125 | ||
126 | /* Retrieve the local username associated with a set of Kerberos | |
127 | * credentials. Hopefully we can use this for the 'empty' username | |
128 | * logins discussed in the draft */ | |
129 | static int | |
130 | ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user) { | |
131 | krb5_principal princ; | |
132 | int retval; | |
133 | ||
134 | if (ssh_gssapi_krb5_init() == 0) | |
135 | return 0; | |
136 | ||
137 | if ((retval=krb5_parse_name(krb_context, client->displayname.value, | |
138 | &princ))) { | |
139 | logit("krb5_parse_name(): %.100s", | |
140 | krb5_get_err_text(krb_context,retval)); | |
141 | return 0; | |
142 | } | |
143 | ||
144 | /* We've got to return a malloc'd string */ | |
145 | *user = (char *)xmalloc(256); | |
146 | if (krb5_aname_to_localname(krb_context, princ, 256, *user)) { | |
147 | xfree(*user); | |
148 | *user = NULL; | |
149 | return(0); | |
150 | } | |
151 | ||
152 | return(1); | |
153 | } | |
154 | ||
155 | /* This writes out any forwarded credentials from the structure populated | |
156 | * during userauth. Called after we have setuid to the user */ | |
157 | ||
158 | static void | |
159 | ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client) | |
160 | { | |
161 | krb5_ccache ccache; | |
162 | krb5_error_code problem; | |
163 | krb5_principal princ; | |
164 | OM_uint32 maj_status, min_status; | |
165 | gss_cred_id_t krb5_cred_handle; | |
166 | int len; | |
167 | const char* new_ccname; | |
168 | ||
169 | if (client->creds == NULL) { | |
170 | debug("No credentials stored"); | |
171 | return; | |
172 | } | |
173 | ||
174 | if (ssh_gssapi_krb5_init() == 0) | |
175 | return; | |
176 | ||
177 | #ifdef HEIMDAL | |
178 | if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) { | |
179 | logit("krb5_cc_gen_new(): %.100s", | |
180 | krb5_get_err_text(krb_context, problem)); | |
181 | return; | |
182 | } | |
183 | #else | |
184 | if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) { | |
185 | logit("ssh_krb5_cc_gen(): %.100s", | |
186 | krb5_get_err_text(krb_context, problem)); | |
187 | return; | |
188 | } | |
189 | #endif /* #ifdef HEIMDAL */ | |
190 | ||
191 | if ((problem = krb5_parse_name(krb_context, | |
192 | client->exportedname.value, &princ))) { | |
193 | logit("krb5_parse_name(): %.100s", | |
194 | krb5_get_err_text(krb_context, problem)); | |
195 | krb5_cc_destroy(krb_context, ccache); | |
196 | return; | |
197 | } | |
198 | ||
199 | if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) { | |
200 | logit("krb5_cc_initialize(): %.100s", | |
201 | krb5_get_err_text(krb_context, problem)); | |
202 | krb5_free_principal(krb_context, princ); | |
203 | krb5_cc_destroy(krb_context, ccache); | |
204 | return; | |
205 | } | |
206 | ||
207 | krb5_free_principal(krb_context, princ); | |
208 | ||
209 | #ifdef MECHGLUE | |
210 | krb5_cred_handle = | |
211 | __gss_get_mechanism_cred(client->creds, | |
212 | &(gssapi_kerberos_mech.oid)); | |
213 | #else | |
214 | krb5_cred_handle = client->creds; | |
215 | #endif | |
216 | ||
217 | if ((maj_status = gss_krb5_copy_ccache(&min_status, | |
218 | krb5_cred_handle, ccache))) { | |
219 | logit("gss_krb5_copy_ccache() failed"); | |
220 | krb5_cc_destroy(krb_context, ccache); | |
221 | return; | |
222 | } | |
223 | ||
224 | new_ccname = krb5_cc_get_name(krb_context, ccache); | |
225 | ||
226 | client->store.envvar = "KRB5CCNAME"; | |
227 | #ifdef USE_CCAPI | |
228 | xasprintf(&client->store.envval, "API:%s", new_ccname); | |
229 | client->store.filename = NULL; | |
230 | #else | |
231 | xasprintf(&client->store.envval, "FILE:%s", new_ccname); | |
232 | client->store.filename = xstrdup(new_ccname); | |
233 | #endif | |
234 | ||
235 | #ifdef USE_PAM | |
236 | if (options.use_pam) | |
237 | do_pam_putenv(client->store.envvar, client->store.envval); | |
238 | #endif | |
239 | ||
240 | krb5_cc_close(krb_context, ccache); | |
241 | ||
242 | return; | |
243 | } | |
244 | ||
245 | #endif /* KRB5 */ | |
246 | ||
247 | #endif /* GSSAPI */ |