summaryrefslogtreecommitdiff
path: root/auth-krb5.c
blob: aaf146e76f51ffdb0984439d46f40eb678d17fa3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
/*
 *    Kerberos v5 authentication and ticket-passing routines.
 * 
 * $FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp $
 * $OpenBSD: auth-krb5.c,v 1.5 2002/02/15 23:54:10 markus Exp $
 */

#include "includes.h"
#include "ssh.h"
#include "ssh1.h"
#include "packet.h"
#include "xmalloc.h"
#include "log.h"
#include "servconf.h"
#include "uidswap.h"
#include "auth.h"

#ifdef KRB5
#include <krb5.h>

extern ServerOptions	 options;

static int
krb5_init(void *context)
{
	Authctxt *authctxt = (Authctxt *)context;
	krb5_error_code problem;
	static int cleanup_registered = 0;

	if (authctxt->krb5_ctx == NULL) {
		problem = krb5_init_context(&authctxt->krb5_ctx);
		if (problem)
			return (problem);
		krb5_init_ets(authctxt->krb5_ctx);
	}
	if (!cleanup_registered) {
		fatal_add_cleanup(krb5_cleanup_proc, authctxt);
		cleanup_registered = 1;
	}
	return (0);
}

/*
 * Try krb5 authentication. server_user is passed for logging purposes
 * only, in auth is received ticket, in client is returned principal
 * from the ticket
 */
int
auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client)
{
	krb5_error_code problem;
	krb5_principal server;
	krb5_data reply;
	krb5_ticket *ticket;
	int fd, ret;

	ret = 0;
	server = NULL;
	ticket = NULL;
	reply.length = 0;

	problem = krb5_init(authctxt);
	if (problem)
		goto err;

	problem = krb5_auth_con_init(authctxt->krb5_ctx,
	    &authctxt->krb5_auth_ctx);
	if (problem)
		goto err;

	fd = packet_get_connection_in();
	problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
	    authctxt->krb5_auth_ctx, &fd);
	if (problem)
		goto err;

	problem = krb5_sname_to_principal(authctxt->krb5_ctx,  NULL, NULL ,
	    KRB5_NT_SRV_HST, &server);
	if (problem)
		goto err;

	problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
	    auth, server, NULL, NULL, &ticket);
	if (problem)
		goto err;

	problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
	    &authctxt->krb5_user);
	if (problem)
		goto err;

	/* if client wants mutual auth */
	problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
	    &reply);
	if (problem)
		goto err;

	/* Check .k5login authorization now. */
	if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
	    authctxt->pw->pw_name))
		goto err;

	if (client)
		krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
		    client);

	packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
	packet_put_string((char *) reply.data, reply.length);
	packet_send();
	packet_write_wait();

	ret = 1;
 err:
	if (server)
		krb5_free_principal(authctxt->krb5_ctx, server);
	if (ticket)
		krb5_free_ticket(authctxt->krb5_ctx, ticket);
	if (reply.length)
		xfree(reply.data);

	if (problem) {
		if (authctxt->krb5_ctx != NULL)
			debug("Kerberos v5 authentication failed: %s",
			    krb5_get_err_text(authctxt->krb5_ctx, problem));
		else
			debug("Kerberos v5 authentication failed: %d",
			    problem);
	}

	return (ret);
}

int
auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
{
	krb5_error_code problem;
	krb5_ccache ccache = NULL;
	char *pname;

	if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
		return (0);

	temporarily_use_uid(authctxt->pw);

	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
	if (problem)
		goto fail;

	problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
	    authctxt->krb5_user);
	if (problem)
		goto fail;

	problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
	    ccache, tgt);
	if (problem)
		goto fail;

	authctxt->krb5_fwd_ccache = ccache;
	ccache = NULL;

	authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);

	problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
	    &pname);
	if (problem)
		goto fail;

	debug("Kerberos v5 TGT accepted (%s)", pname);

	restore_uid();

	return (1);

 fail:
	if (problem)
		debug("Kerberos v5 TGT passing failed: %s",
		    krb5_get_err_text(authctxt->krb5_ctx, problem));
	if (ccache)
		krb5_cc_destroy(authctxt->krb5_ctx, ccache);

	restore_uid();

	return (0);
}

int
auth_krb5_password(Authctxt *authctxt, const char *password)
{
	krb5_error_code problem;

	if (authctxt->pw == NULL)
		return (0);

	temporarily_use_uid(authctxt->pw);

	problem = krb5_init(authctxt);
	if (problem)
		goto out;

	problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
		    &authctxt->krb5_user);
	if (problem)
		goto out;

	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
	    &authctxt->krb5_fwd_ccache);
	if (problem)
		goto out;

	problem = krb5_cc_initialize(authctxt->krb5_ctx,
	    authctxt->krb5_fwd_ccache, authctxt->krb5_user);
	if (problem)
		goto out;

	restore_uid();
	problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
	    authctxt->krb5_fwd_ccache, password, 1, NULL);
	temporarily_use_uid(authctxt->pw);

	if (problem)
		goto out;

	authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);

 out:
	restore_uid();

	if (problem) {
		if (authctxt->krb5_ctx != NULL)
			debug("Kerberos password authentication failed: %s",
			    krb5_get_err_text(authctxt->krb5_ctx, problem));
		else
			debug("Kerberos password authentication failed: %d",
			    problem);

		krb5_cleanup_proc(authctxt);

		if (options.kerberos_or_local_passwd)
			return (-1);
		else
			return (0);
	}
	return (1);
}

void
krb5_cleanup_proc(void *context)
{
	Authctxt *authctxt = (Authctxt *)context;

	debug("krb5_cleanup_proc called");
	if (authctxt->krb5_fwd_ccache) {
		krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
		authctxt->krb5_fwd_ccache = NULL;
	}
	if (authctxt->krb5_user) {
		krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
		authctxt->krb5_user = NULL;
	}
	if (authctxt->krb5_auth_ctx) {
		krb5_auth_con_free(authctxt->krb5_ctx,
		    authctxt->krb5_auth_ctx);
		authctxt->krb5_auth_ctx = NULL;
	}
	if (authctxt->krb5_ctx) {
		krb5_free_context(authctxt->krb5_ctx);
		authctxt->krb5_ctx = NULL;
	}
}

#endif /* KRB5 */