source: heimdal/trunk/appl/kx/krb5.c@ 4

Last change on this file since 4 was 1, checked in by Paul Smedley, 10 years ago

Initial commit of Heimdal 1.5.3
File size: 10.6 KB
Line 
1/*
2 * Copyright (c) 1995 - 2005 Kungliga Tekniska Högskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * 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 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "kx.h"
35
36RCSID("$Id$");
37
38#ifdef KRB5
39
40struct krb5_kx_context {
41 krb5_context context;
42 krb5_keyblock *keyblock;
43 krb5_crypto crypto;
44 krb5_principal client;
45 krb5_log_facility *log;
46
47};
48
49typedef struct krb5_kx_context krb5_kx_context;
50
51#define K5DATA(kc) ((krb5_kx_context*)kc->data)
52#define CONTEXT(kc) (K5DATA(kc)->context)
53
54/*
55 *
56 */
57
58static void
59ksyslog(krb5_context context, krb5_error_code ret, const char *fmt, ...)
60 __attribute__((__format__(__printf__, 3, 0)));
61
62static void
63ksyslog(krb5_context context, krb5_error_code ret, const char *fmt, ...)
64{
65 const char *msg;
66 char *str = NULL;
67 va_list va;
68
69 msg = krb5_get_error_message(context, ret);
70
71 va_start(va, fmt);
72 vasprintf(&str, fmt, va);
73 va_end(va);
74
75 syslog(LOG_ERR, "%s: %s", str, msg);
76
77 krb5_free_error_message(context, msg);
78 free(str);
79}
80
81/*
82 * Destroy the krb5 context in `c'.
83 */
84
85static void
86krb5_destroy (kx_context *kc)
87{
88 if (K5DATA(kc)->keyblock)
89 krb5_free_keyblock (CONTEXT(kc), K5DATA(kc)->keyblock);
90 if (K5DATA(kc)->crypto)
91 krb5_crypto_destroy (CONTEXT(kc), K5DATA(kc)->crypto);
92 if (K5DATA(kc)->client)
93 krb5_free_principal (CONTEXT(kc), K5DATA(kc)->client);
94 if (CONTEXT(kc))
95 krb5_free_context (CONTEXT(kc));
96 memset (kc->data, 0, sizeof(krb5_kx_context));
97 free (kc->data);
98}
99
100/*
101 * Read the authentication information from `s' and return 0 if
102 * succesful, else -1.
103 */
104
105static int
106krb5_authenticate (kx_context *kc, int s)
107{
108 krb5_auth_context auth_context = NULL;
109 krb5_error_code ret;
110 krb5_principal server;
111 const char *host = kc->host;
112
113 ret = krb5_sname_to_principal (CONTEXT(kc),
114 host, "host", KRB5_NT_SRV_HST, &server);
115 if (ret) {
116 krb5_warn (CONTEXT(kc), ret, "krb5_sname_to_principal: %s", host);
117 return 1;
118 }
119
120 ret = krb5_sendauth (CONTEXT(kc),
121 &auth_context,
122 &s,
123 KX_VERSION,
124 NULL,
125 server,
126 AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
127 NULL,
128 NULL,
129 NULL,
130 NULL,
131 NULL,
132 NULL);
133 if (ret) {
134 if(ret != KRB5_SENDAUTH_BADRESPONSE)
135 krb5_warn (CONTEXT(kc), ret, "krb5_sendauth: %s", host);
136 return 1;
137 }
138
139 ret = krb5_auth_con_getkey (CONTEXT(kc), auth_context,
140 &K5DATA(kc)->keyblock);
141 if (ret) {
142 krb5_warn (CONTEXT(kc), ret, "krb5_auth_con_getkey: %s", host);
143 krb5_auth_con_free (CONTEXT(kc), auth_context);
144 return 1;
145 }
146
147 ret = krb5_crypto_init (CONTEXT(kc), K5DATA(kc)->keyblock,
148 0, &K5DATA(kc)->crypto);
149 if (ret) {
150 krb5_warn (CONTEXT(kc), ret, "krb5_crypto_init");
151 krb5_auth_con_free (CONTEXT(kc), auth_context);
152 return 1;
153 }
154 return 0;
155}
156
157/*
158 * Read an encapsulated krb5 packet from `fd' into `buf' (of size
159 * `len'). Return the number of bytes read or 0 on EOF or -1 on
160 * error.
161 */
162
163static ssize_t
164krb5_read (kx_context *kc,
165 int fd, void *buf, size_t len)
166{
167 size_t data_len, outer_len;
168 krb5_error_code ret;
169 unsigned char tmp[4];
170 krb5_data data;
171 int l;
172
173 l = krb5_net_read (CONTEXT(kc), &fd, tmp, 4);
174 if (l == 0)
175 return l;
176 if (l != 4)
177 return -1;
178 data_len = (tmp[0] << 24) | (tmp[1] << 16) | (tmp[2] << 8) | tmp[3];
179 outer_len = krb5_get_wrapped_length (CONTEXT(kc),
180 K5DATA(kc)->crypto, data_len);
181 if (outer_len > len)
182 return -1;
183 if (krb5_net_read (CONTEXT(kc), &fd, buf, outer_len) != outer_len)
184 return -1;
185
186 ret = krb5_decrypt (CONTEXT(kc), K5DATA(kc)->crypto,
187 KRB5_KU_OTHER_ENCRYPTED,
188 buf, outer_len, &data);
189 if (ret) {
190 krb5_warn (CONTEXT(kc), ret, "krb5_decrypt");
191 return -1;
192 }
193 if (data_len > data.length) {
194 krb5_data_free (&data);
195 return -1;
196 }
197 memmove (buf, data.data, data_len);
198 krb5_data_free (&data);
199 return data_len;
200}
201
202/*
203 * Write an encapsulated krb5 packet on `fd' with the data in `buf,
204 * len'. Return len or -1 on error.
205 */
206
207static ssize_t
208krb5_write(kx_context *kc,
209 int fd, const void *buf, size_t len)
210{
211 krb5_data data;
212 krb5_error_code ret;
213 unsigned char tmp[4];
214 size_t outlen;
215
216 ret = krb5_encrypt (CONTEXT(kc), K5DATA(kc)->crypto,
217 KRB5_KU_OTHER_ENCRYPTED,
218 buf, len, &data);
219 if (ret){
220 krb5_warn (CONTEXT(kc), ret, "krb5_write");
221 return -1;
222 }
223
224 outlen = data.length;
225 tmp[0] = (len >> 24) & 0xFF;
226 tmp[1] = (len >> 16) & 0xFF;
227 tmp[2] = (len >> 8) & 0xFF;
228 tmp[3] = (len >> 0) & 0xFF;
229
230 if (krb5_net_write (CONTEXT(kc), &fd, tmp, 4) != 4 ||
231 krb5_net_write (CONTEXT(kc), &fd, data.data, outlen) != outlen) {
232 krb5_data_free (&data);
233 return -1;
234 }
235 krb5_data_free (&data);
236 return len;
237}
238
239/*
240 * Copy from the unix socket `from_fd' encrypting to `to_fd'.
241 * Return 0, -1 or len.
242 */
243
244static int
245copy_out (kx_context *kc, int from_fd, int to_fd)
246{
247 char buf[32768];
248 ssize_t len;
249
250 len = read (from_fd, buf, sizeof(buf));
251 if (len == 0)
252 return 0;
253 if (len < 0) {
254 krb5_warn (CONTEXT(kc), errno, "read");
255 return len;
256 }
257 return krb5_write (kc, to_fd, buf, len);
258}
259
260/*
261 * Copy from the socket `from_fd' decrypting to `to_fd'.
262 * Return 0, -1 or len.
263 */
264
265static int
266copy_in (kx_context *kc, int from_fd, int to_fd)
267{
268 char buf[33000]; /* XXX */
269
270 ssize_t len;
271
272 len = krb5_read (kc, from_fd, buf, sizeof(buf));
273 if (len == 0)
274 return 0;
275 if (len < 0) {
276 krb5_warn (CONTEXT(kc), errno, "krb5_read");
277 return len;
278 }
279
280 return krb5_net_write (CONTEXT(kc), &to_fd, buf, len);
281}
282
283/*
284 * Copy data between `fd1' and `fd2', encrypting in one direction and
285 * decrypting in the other.
286 */
287
288static int
289krb5_copy_encrypted (kx_context *kc, int fd1, int fd2)
290{
291 for (;;) {
292 fd_set fdset;
293 int ret;
294
295 if (fd1 >= FD_SETSIZE || fd2 >= FD_SETSIZE) {
296 krb5_warnx (CONTEXT(kc), "fd too large");
297 return 1;
298 }
299
300 FD_ZERO(&fdset);
301 FD_SET(fd1, &fdset);
302 FD_SET(fd2, &fdset);
303
304 ret = select (max(fd1, fd2)+1, &fdset, NULL, NULL, NULL);
305 if (ret < 0 && errno != EINTR) {
306 krb5_warn (CONTEXT(kc), errno, "select");
307 return 1;
308 }
309 if (FD_ISSET(fd1, &fdset)) {
310 ret = copy_out (kc, fd1, fd2);
311 if (ret <= 0)
312 return ret;
313 }
314 if (FD_ISSET(fd2, &fdset)) {
315 ret = copy_in (kc, fd2, fd1);
316 if (ret <= 0)
317 return ret;
318 }
319 }
320}
321
322/*
323 * Return 0 if the user authenticated on `kc' is allowed to login as
324 * `user'.
325 */
326
327static int
328krb5_userok (kx_context *kc, char *user)
329{
330 krb5_error_code ret;
331 char *tmp;
332
333 ret = krb5_unparse_name (CONTEXT(kc), K5DATA(kc)->client, &tmp);
334 if (ret)
335 krb5_err (CONTEXT(kc), 1, ret, "krb5_unparse_name");
336 kc->user = tmp;
337
338 return !krb5_kuserok (CONTEXT(kc), K5DATA(kc)->client, user);
339}
340
341/*
342 * Create an instance of an krb5 context.
343 */
344
345void
346krb5_make_context (kx_context *kc)
347{
348 krb5_kx_context *c;
349 krb5_error_code ret;
350
351 kc->authenticate = krb5_authenticate;
352 kc->userok = krb5_userok;
353 kc->read = krb5_read;
354 kc->write = krb5_write;
355 kc->copy_encrypted = krb5_copy_encrypted;
356 kc->destroy = krb5_destroy;
357 kc->user = NULL;
358 kc->data = malloc(sizeof(krb5_kx_context));
359
360 if (kc->data == NULL) {
361 syslog (LOG_ERR, "failed to malloc %lu bytes",
362 (unsigned long)sizeof(krb5_kx_context));
363 exit(1);
364 }
365 memset (kc->data, 0, sizeof(krb5_kx_context));
366 c = (krb5_kx_context *)kc->data;
367 ret = krb5_init_context (&c->context);
368 if (ret) {
369 syslog (LOG_ERR, "failed initialise krb5 context");
370 exit(1);
371 }
372}
373
374/*
375 * Receive authentication information on `sock' (first four bytes
376 * in `buf').
377 */
378
379int
380recv_v5_auth (kx_context *kc, int sock, u_char *buf)
381{
382 uint32_t len;
383 krb5_error_code ret;
384 krb5_principal server;
385 krb5_auth_context auth_context = NULL;
386 krb5_ticket *ticket;
387
388 if (memcmp (buf, "\x00\x00\x00\x13", 4) != 0)
389 return 1;
390 len = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3]);
391 if (net_read(sock, buf, len) != len) {
392 syslog (LOG_ERR, "read: %m");
393 exit (1);
394 }
395 if (len != sizeof(KRB5_SENDAUTH_VERSION)
396 || memcmp (buf, KRB5_SENDAUTH_VERSION, len) != 0) {
397 syslog (LOG_ERR, "bad sendauth version: %.8s", buf);
398 exit (1);
399 }
400
401 krb5_make_context (kc);
402 krb5_openlog(CONTEXT(kc), "kxd", &K5DATA(kc)->log);
403 krb5_set_warn_dest(CONTEXT(kc), K5DATA(kc)->log);
404
405 ret = krb5_sock_to_principal (CONTEXT(kc), sock, "host",
406 KRB5_NT_SRV_HST, &server);
407 if (ret) {
408 ksyslog (CONTEXT(kc), ret, "krb5_sock_to_principal");
409 exit (1);
410 }
411
412 ret = krb5_recvauth (CONTEXT(kc),
413 &auth_context,
414 &sock,
415 KX_VERSION,
416 server,
417 KRB5_RECVAUTH_IGNORE_VERSION,
418 NULL,
419 &ticket);
420 krb5_free_principal (CONTEXT(kc), server);
421 if (ret) {
422 ksyslog (CONTEXT(kc), ret, "krb5_recvauth");
423 exit (1);
424 }
425
426 ret = krb5_auth_con_getkey (CONTEXT(kc), auth_context, &K5DATA(kc)->keyblock);
427 if (ret) {
428 ksyslog (CONTEXT(kc), ret, "krb5_auth_con_getkey");
429 exit (1);
430 }
431
432 ret = krb5_crypto_init (CONTEXT(kc), K5DATA(kc)->keyblock, 0, &K5DATA(kc)->crypto);
433 if (ret) {
434 ksyslog (CONTEXT(kc), ret, "krb5_crypto_init");
435 exit (1);
436 }
437
438 K5DATA(kc)->client = ticket->client;
439 ticket->client = NULL;
440 krb5_free_ticket (CONTEXT(kc), ticket);
441
442 krb5_auth_con_free(CONTEXT(kc), auth_context);
443
444 return 0;
445}
446
447#endif /* KRB5 */
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