1 /* $OpenBSD: auth-krb5.c,v 1.19 2006/08/03 03:34:41 deraadt Exp $ */
2 /*
3 * Kerberos v5 authentication and ticket-passing routines.
4 *
5 * $FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp $
6 */
7 /*
8 * Copyright (c) 2002 Daniel Kouril. All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include "includes.h"
32
33 #include <sys/types.h>
34 #include <pwd.h>
35 #include <stdarg.h>
36
37 #include "xmalloc.h"
38 #include "ssh.h"
39 #include "ssh1.h"
40 #include "packet.h"
41 #include "log.h"
42 #include "buffer.h"
43 #include "servconf.h"
44 #include "uidswap.h"
45 #include "key.h"
46 #include "hostfile.h"
47 #include "auth.h"
48
49 #ifdef KRB5
50 #include <errno.h>
51 #include <unistd.h>
52 #include <string.h>
53 #include <krb5.h>
54
55 extern ServerOptions options;
56
57 static int
krb5_init(void * context)58 krb5_init(void *context)
59 {
60 Authctxt *authctxt = (Authctxt *)context;
61 krb5_error_code problem;
62
63 if (authctxt->krb5_ctx == NULL) {
64 problem = krb5_init_context(&authctxt->krb5_ctx);
65 if (problem)
66 return (problem);
67 }
68 return (0);
69 }
70
71 int
auth_krb5_password(Authctxt * authctxt,const char * password)72 auth_krb5_password(Authctxt *authctxt, const char *password)
73 {
74 #ifndef HEIMDAL
75 krb5_creds creds;
76 krb5_principal server;
77 #endif
78 krb5_error_code problem;
79 krb5_ccache ccache = NULL;
80 int len;
81 char *client, *platform_client;
82
83 /* get platform-specific kerberos client principal name (if it exists) */
84 platform_client = platform_krb5_get_principal_name(authctxt->pw->pw_name);
85 client = platform_client ? platform_client : authctxt->pw->pw_name;
86
87 temporarily_use_uid(authctxt->pw);
88
89 problem = krb5_init(authctxt);
90 if (problem)
91 goto out;
92
93 problem = krb5_parse_name(authctxt->krb5_ctx, client,
94 &authctxt->krb5_user);
95 if (problem)
96 goto out;
97
98 #ifdef HEIMDAL
99 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
100 if (problem)
101 goto out;
102
103 problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
104 authctxt->krb5_user);
105 if (problem)
106 goto out;
107
108 restore_uid();
109
110 problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
111 ccache, password, 1, NULL);
112
113 temporarily_use_uid(authctxt->pw);
114
115 if (problem)
116 goto out;
117
118 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
119 &authctxt->krb5_fwd_ccache);
120 if (problem)
121 goto out;
122
123 problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
124 authctxt->krb5_fwd_ccache);
125 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
126 ccache = NULL;
127 if (problem)
128 goto out;
129
130 #else
131 problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
132 authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
133 if (problem)
134 goto out;
135
136 problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
137 KRB5_NT_SRV_HST, &server);
138 if (problem)
139 goto out;
140
141 restore_uid();
142 problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
143 NULL, NULL, NULL);
144 krb5_free_principal(authctxt->krb5_ctx, server);
145 temporarily_use_uid(authctxt->pw);
146 if (problem)
147 goto out;
148
149 if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user, client)) {
150 problem = -1;
151 goto out;
152 }
153
154 problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
155 if (problem)
156 goto out;
157
158 problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
159 authctxt->krb5_user);
160 if (problem)
161 goto out;
162
163 problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
164 &creds);
165 if (problem)
166 goto out;
167 #endif
168
169 authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
170
171 len = strlen(authctxt->krb5_ticket_file) + 6;
172 authctxt->krb5_ccname = xmalloc(len);
173 snprintf(authctxt->krb5_ccname, len, "FILE:%s",
174 authctxt->krb5_ticket_file);
175
176 #ifdef USE_PAM
177 if (options.use_pam)
178 do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
179 #endif
180
181 out:
182 restore_uid();
183
184 if (platform_client != NULL)
185 xfree(platform_client);
186
187 if (problem) {
188 if (ccache)
189 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
190
191 if (authctxt->krb5_ctx != NULL && problem!=-1)
192 debug("Kerberos password authentication failed: %s",
193 krb5_get_err_text(authctxt->krb5_ctx, problem));
194 else
195 debug("Kerberos password authentication failed: %d",
196 problem);
197
198 krb5_cleanup_proc(authctxt);
199
200 if (options.kerberos_or_local_passwd)
201 return (-1);
202 else
203 return (0);
204 }
205 return (authctxt->valid ? 1 : 0);
206 }
207
208 void
krb5_cleanup_proc(Authctxt * authctxt)209 krb5_cleanup_proc(Authctxt *authctxt)
210 {
211 debug("krb5_cleanup_proc called");
212 if (authctxt->krb5_fwd_ccache) {
213 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
214 authctxt->krb5_fwd_ccache = NULL;
215 }
216 if (authctxt->krb5_user) {
217 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
218 authctxt->krb5_user = NULL;
219 }
220 if (authctxt->krb5_ctx) {
221 krb5_free_context(authctxt->krb5_ctx);
222 authctxt->krb5_ctx = NULL;
223 }
224 }
225
226 #ifndef HEIMDAL
227 krb5_error_code
ssh_krb5_cc_gen(krb5_context ctx,krb5_ccache * ccache)228 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
229 int tmpfd, ret;
230 char ccname[40];
231 mode_t old_umask;
232
233 ret = snprintf(ccname, sizeof(ccname),
234 "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
235 if (ret < 0 || (size_t)ret >= sizeof(ccname))
236 return ENOMEM;
237
238 old_umask = umask(0177);
239 tmpfd = mkstemp(ccname + strlen("FILE:"));
240 umask(old_umask);
241 if (tmpfd == -1) {
242 logit("mkstemp(): %.100s", strerror(errno));
243 return errno;
244 }
245
246 if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
247 logit("fchmod(): %.100s", strerror(errno));
248 close(tmpfd);
249 return errno;
250 }
251 close(tmpfd);
252
253 return (krb5_cc_resolve(ctx, ccname, ccache));
254 }
255 #endif /* !HEIMDAL */
256 #endif /* KRB5 */
257