xref: /freebsd/crypto/openssh/auth-krb5.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
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  * $xFreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp$
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 __RCSID("$FreeBSD$");
33 
34 #include <sys/types.h>
35 #include <pwd.h>
36 #include <stdarg.h>
37 
38 #include "xmalloc.h"
39 #include "ssh.h"
40 #include "ssh1.h"
41 #include "packet.h"
42 #include "log.h"
43 #include "buffer.h"
44 #include "servconf.h"
45 #include "uidswap.h"
46 #include "key.h"
47 #include "hostfile.h"
48 #include "auth.h"
49 
50 #ifdef KRB5
51 #include <errno.h>
52 #include <unistd.h>
53 #include <string.h>
54 #include <krb5.h>
55 
56 extern ServerOptions	 options;
57 
58 static int
59 krb5_init(void *context)
60 {
61 	Authctxt *authctxt = (Authctxt *)context;
62 	krb5_error_code problem;
63 
64 	if (authctxt->krb5_ctx == NULL) {
65 		problem = krb5_init_context(&authctxt->krb5_ctx);
66 		if (problem)
67 			return (problem);
68 	}
69 	return (0);
70 }
71 
72 int
73 auth_krb5_password(Authctxt *authctxt, const char *password)
74 {
75 #ifndef HEIMDAL
76 	krb5_creds creds;
77 	krb5_principal server;
78 #endif
79 	krb5_error_code problem;
80 	krb5_ccache ccache = NULL;
81 	int len;
82 
83 	temporarily_use_uid(authctxt->pw);
84 
85 	problem = krb5_init(authctxt);
86 	if (problem)
87 		goto out;
88 
89 	problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
90 		    &authctxt->krb5_user);
91 	if (problem)
92 		goto out;
93 
94 #ifdef HEIMDAL
95 	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
96 	if (problem)
97 		goto out;
98 
99 	problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
100 		authctxt->krb5_user);
101 	if (problem)
102 		goto out;
103 
104 	restore_uid();
105 
106 	problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
107 	    ccache, password, 1, NULL);
108 
109 	temporarily_use_uid(authctxt->pw);
110 
111 	if (problem)
112 		goto out;
113 
114 	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
115 	    &authctxt->krb5_fwd_ccache);
116 	if (problem)
117 		goto out;
118 
119 	problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
120 	    authctxt->krb5_fwd_ccache);
121 	krb5_cc_destroy(authctxt->krb5_ctx, ccache);
122 	ccache = NULL;
123 	if (problem)
124 		goto out;
125 
126 #else
127 	problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
128 	    authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
129 	if (problem)
130 		goto out;
131 
132 	problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
133 	    KRB5_NT_SRV_HST, &server);
134 	if (problem)
135 		goto out;
136 
137 	restore_uid();
138 	problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
139 	    NULL, NULL, NULL);
140 	krb5_free_principal(authctxt->krb5_ctx, server);
141 	temporarily_use_uid(authctxt->pw);
142 	if (problem)
143 		goto out;
144 
145 	if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
146 			  authctxt->pw->pw_name)) {
147 		problem = -1;
148 		goto out;
149 	}
150 
151 	problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
152 	if (problem)
153 		goto out;
154 
155 	problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
156 				     authctxt->krb5_user);
157 	if (problem)
158 		goto out;
159 
160 	problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
161 				 &creds);
162 	if (problem)
163 		goto out;
164 #endif
165 
166 	authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
167 
168 	len = strlen(authctxt->krb5_ticket_file) + 6;
169 	authctxt->krb5_ccname = xmalloc(len);
170 	snprintf(authctxt->krb5_ccname, len, "FILE:%s",
171 	    authctxt->krb5_ticket_file);
172 
173 #ifdef USE_PAM
174 	if (options.use_pam)
175 		do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
176 #endif
177 
178  out:
179 	restore_uid();
180 
181 	if (problem) {
182 		if (ccache)
183 			krb5_cc_destroy(authctxt->krb5_ctx, ccache);
184 
185 		if (authctxt->krb5_ctx != NULL && problem!=-1)
186 			debug("Kerberos password authentication failed: %s",
187 			    krb5_get_err_text(authctxt->krb5_ctx, problem));
188 		else
189 			debug("Kerberos password authentication failed: %d",
190 			    problem);
191 
192 		krb5_cleanup_proc(authctxt);
193 
194 		if (options.kerberos_or_local_passwd)
195 			return (-1);
196 		else
197 			return (0);
198 	}
199 	return (authctxt->valid ? 1 : 0);
200 }
201 
202 void
203 krb5_cleanup_proc(Authctxt *authctxt)
204 {
205 	debug("krb5_cleanup_proc called");
206 	if (authctxt->krb5_fwd_ccache) {
207 		krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
208 		authctxt->krb5_fwd_ccache = NULL;
209 	}
210 	if (authctxt->krb5_user) {
211 		krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
212 		authctxt->krb5_user = NULL;
213 	}
214 	if (authctxt->krb5_ctx) {
215 		krb5_free_context(authctxt->krb5_ctx);
216 		authctxt->krb5_ctx = NULL;
217 	}
218 }
219 
220 #ifndef HEIMDAL
221 krb5_error_code
222 ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
223 	int tmpfd, ret;
224 	char ccname[40];
225 	mode_t old_umask;
226 
227 	ret = snprintf(ccname, sizeof(ccname),
228 	    "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
229 	if (ret < 0 || (size_t)ret >= sizeof(ccname))
230 		return ENOMEM;
231 
232 	old_umask = umask(0177);
233 	tmpfd = mkstemp(ccname + strlen("FILE:"));
234 	umask(old_umask);
235 	if (tmpfd == -1) {
236 		logit("mkstemp(): %.100s", strerror(errno));
237 		return errno;
238 	}
239 
240 	if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
241 		logit("fchmod(): %.100s", strerror(errno));
242 		close(tmpfd);
243 		return errno;
244 	}
245 	close(tmpfd);
246 
247 	return (krb5_cc_resolve(ctx, ccname, ccache));
248 }
249 #endif /* !HEIMDAL */
250 #endif /* KRB5 */
251