xref: /freebsd/crypto/heimdal/lib/krb5/keytab_file.c (revision f39bffc62c1395bde25d152c7f68fdf7cbaab414)
1 /*
2  * Copyright (c) 1997 - 2008 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 "krb5_locl.h"
35 
36 #define KRB5_KT_VNO_1 1
37 #define KRB5_KT_VNO_2 2
38 #define KRB5_KT_VNO   KRB5_KT_VNO_2
39 
40 #define KRB5_KT_FL_JAVA 1
41 
42 
43 /* file operations -------------------------------------------- */
44 
45 struct fkt_data {
46     char *filename;
47     int flags;
48 };
49 
50 static krb5_error_code
51 krb5_kt_ret_data(krb5_context context,
52 		 krb5_storage *sp,
53 		 krb5_data *data)
54 {
55     int ret;
56     int16_t size;
57     ret = krb5_ret_int16(sp, &size);
58     if(ret)
59 	return ret;
60     data->length = size;
61     data->data = malloc(size);
62     if (data->data == NULL) {
63 	krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
64 	return ENOMEM;
65     }
66     ret = krb5_storage_read(sp, data->data, size);
67     if(ret != size)
68 	return (ret < 0)? errno : KRB5_KT_END;
69     return 0;
70 }
71 
72 static krb5_error_code
73 krb5_kt_ret_string(krb5_context context,
74 		   krb5_storage *sp,
75 		   heim_general_string *data)
76 {
77     int ret;
78     int16_t size;
79     ret = krb5_ret_int16(sp, &size);
80     if(ret)
81 	return ret;
82     *data = malloc(size + 1);
83     if (*data == NULL) {
84 	krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
85 	return ENOMEM;
86     }
87     ret = krb5_storage_read(sp, *data, size);
88     (*data)[size] = '\0';
89     if(ret != size)
90 	return (ret < 0)? errno : KRB5_KT_END;
91     return 0;
92 }
93 
94 static krb5_error_code
95 krb5_kt_store_data(krb5_context context,
96 		   krb5_storage *sp,
97 		   krb5_data data)
98 {
99     int ret;
100     ret = krb5_store_int16(sp, data.length);
101     if(ret < 0)
102 	return ret;
103     ret = krb5_storage_write(sp, data.data, data.length);
104     if(ret != (int)data.length){
105 	if(ret < 0)
106 	    return errno;
107 	return KRB5_KT_END;
108     }
109     return 0;
110 }
111 
112 static krb5_error_code
113 krb5_kt_store_string(krb5_storage *sp,
114 		     heim_general_string data)
115 {
116     int ret;
117     size_t len = strlen(data);
118     ret = krb5_store_int16(sp, len);
119     if(ret < 0)
120 	return ret;
121     ret = krb5_storage_write(sp, data, len);
122     if(ret != (int)len){
123 	if(ret < 0)
124 	    return errno;
125 	return KRB5_KT_END;
126     }
127     return 0;
128 }
129 
130 static krb5_error_code
131 krb5_kt_ret_keyblock(krb5_context context,
132 		     struct fkt_data *fkt,
133 		     krb5_storage *sp,
134 		     krb5_keyblock *p)
135 {
136     int ret;
137     int16_t tmp;
138 
139     ret = krb5_ret_int16(sp, &tmp); /* keytype + etype */
140     if(ret)  {
141 	krb5_set_error_message(context, ret,
142 			       N_("Cant read keyblock from file %s", ""),
143 			       fkt->filename);
144 	return ret;
145     }
146     p->keytype = tmp;
147     ret = krb5_kt_ret_data(context, sp, &p->keyvalue);
148     if (ret)
149 	krb5_set_error_message(context, ret,
150 			       N_("Cant read keyblock from file %s", ""),
151 			       fkt->filename);
152     return ret;
153 }
154 
155 static krb5_error_code
156 krb5_kt_store_keyblock(krb5_context context,
157 		       struct fkt_data *fkt,
158 		       krb5_storage *sp,
159 		       krb5_keyblock *p)
160 {
161     int ret;
162 
163     ret = krb5_store_int16(sp, p->keytype); /* keytype + etype */
164     if(ret) {
165 	krb5_set_error_message(context, ret,
166 			       N_("Cant store keyblock to file %s", ""),
167 			       fkt->filename);
168 	return ret;
169     }
170     ret = krb5_kt_store_data(context, sp, p->keyvalue);
171     if (ret)
172 	krb5_set_error_message(context, ret,
173 			       N_("Cant store keyblock to file %s", ""),
174 			       fkt->filename);
175     return ret;
176 }
177 
178 
179 static krb5_error_code
180 krb5_kt_ret_principal(krb5_context context,
181 		      struct fkt_data *fkt,
182 		      krb5_storage *sp,
183 		      krb5_principal *princ)
184 {
185     size_t i;
186     int ret;
187     krb5_principal p;
188     int16_t len;
189 
190     ALLOC(p, 1);
191     if(p == NULL) {
192 	krb5_set_error_message(context, ENOMEM,
193 			       N_("malloc: out of memory", ""));
194 	return ENOMEM;
195     }
196 
197     ret = krb5_ret_int16(sp, &len);
198     if(ret) {
199 	krb5_set_error_message(context, ret,
200 			       N_("Failed decoding length of "
201 				  "keytab principal in keytab file %s", ""),
202 			       fkt->filename);
203 	goto out;
204     }
205     if(krb5_storage_is_flags(sp, KRB5_STORAGE_PRINCIPAL_WRONG_NUM_COMPONENTS))
206 	len--;
207     if (len < 0) {
208 	ret = KRB5_KT_END;
209 	krb5_set_error_message(context, ret,
210 			       N_("Keytab principal contains "
211 				  "invalid length in keytab %s", ""),
212 			       fkt->filename);
213 	goto out;
214     }
215     ret = krb5_kt_ret_string(context, sp, &p->realm);
216     if(ret) {
217 	krb5_set_error_message(context, ret,
218 			       N_("Can't read realm from keytab: %s", ""),
219 			       fkt->filename);
220 	goto out;
221     }
222     p->name.name_string.val = calloc(len, sizeof(*p->name.name_string.val));
223     if(p->name.name_string.val == NULL) {
224 	ret = ENOMEM;
225 	krb5_set_error_message(context, ret, N_("malloc: out of memory", ""));
226 	goto out;
227     }
228     p->name.name_string.len = len;
229     for(i = 0; i < p->name.name_string.len; i++){
230 	ret = krb5_kt_ret_string(context, sp, p->name.name_string.val + i);
231 	if(ret) {
232 	    krb5_set_error_message(context, ret,
233 				   N_("Can't read principal from "
234 				      "keytab: %s", ""),
235 				   fkt->filename);
236 	    goto out;
237 	}
238     }
239     if (krb5_storage_is_flags(sp, KRB5_STORAGE_PRINCIPAL_NO_NAME_TYPE))
240 	p->name.name_type = KRB5_NT_UNKNOWN;
241     else {
242 	int32_t tmp32;
243 	ret = krb5_ret_int32(sp, &tmp32);
244 	p->name.name_type = tmp32;
245 	if (ret) {
246 	    krb5_set_error_message(context, ret,
247 				   N_("Can't read name-type from "
248 				      "keytab: %s", ""),
249 				   fkt->filename);
250 	    goto out;
251 	}
252     }
253     *princ = p;
254     return 0;
255 out:
256     krb5_free_principal(context, p);
257     return ret;
258 }
259 
260 static krb5_error_code
261 krb5_kt_store_principal(krb5_context context,
262 			krb5_storage *sp,
263 			krb5_principal p)
264 {
265     size_t i;
266     int ret;
267 
268     if(krb5_storage_is_flags(sp, KRB5_STORAGE_PRINCIPAL_WRONG_NUM_COMPONENTS))
269 	ret = krb5_store_int16(sp, p->name.name_string.len + 1);
270     else
271 	ret = krb5_store_int16(sp, p->name.name_string.len);
272     if(ret) return ret;
273     ret = krb5_kt_store_string(sp, p->realm);
274     if(ret) return ret;
275     for(i = 0; i < p->name.name_string.len; i++){
276 	ret = krb5_kt_store_string(sp, p->name.name_string.val[i]);
277 	if(ret)
278 	    return ret;
279     }
280     if(!krb5_storage_is_flags(sp, KRB5_STORAGE_PRINCIPAL_NO_NAME_TYPE)) {
281 	ret = krb5_store_int32(sp, p->name.name_type);
282 	if(ret)
283 	    return ret;
284     }
285 
286     return 0;
287 }
288 
289 static krb5_error_code KRB5_CALLCONV
290 fkt_resolve(krb5_context context, const char *name, krb5_keytab id)
291 {
292     struct fkt_data *d;
293 
294     d = malloc(sizeof(*d));
295     if(d == NULL) {
296 	krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
297 	return ENOMEM;
298     }
299     d->filename = strdup(name);
300     if(d->filename == NULL) {
301 	free(d);
302 	krb5_set_error_message(context, ENOMEM, N_("malloc: out of memory", ""));
303 	return ENOMEM;
304     }
305     d->flags = 0;
306     id->data = d;
307     return 0;
308 }
309 
310 static krb5_error_code KRB5_CALLCONV
311 fkt_resolve_java14(krb5_context context, const char *name, krb5_keytab id)
312 {
313     krb5_error_code ret;
314 
315     ret = fkt_resolve(context, name, id);
316     if (ret == 0) {
317 	struct fkt_data *d = id->data;
318 	d->flags |= KRB5_KT_FL_JAVA;
319     }
320     return ret;
321 }
322 
323 static krb5_error_code KRB5_CALLCONV
324 fkt_close(krb5_context context, krb5_keytab id)
325 {
326     struct fkt_data *d = id->data;
327     free(d->filename);
328     free(d);
329     return 0;
330 }
331 
332 static krb5_error_code KRB5_CALLCONV
333 fkt_destroy(krb5_context context, krb5_keytab id)
334 {
335     struct fkt_data *d = id->data;
336     _krb5_erase_file(context, d->filename);
337     return 0;
338 }
339 
340 static krb5_error_code KRB5_CALLCONV
341 fkt_get_name(krb5_context context,
342 	     krb5_keytab id,
343 	     char *name,
344 	     size_t namesize)
345 {
346     /* This function is XXX */
347     struct fkt_data *d = id->data;
348     strlcpy(name, d->filename, namesize);
349     return 0;
350 }
351 
352 static void
353 storage_set_flags(krb5_context context, krb5_storage *sp, int vno)
354 {
355     int flags = 0;
356     switch(vno) {
357     case KRB5_KT_VNO_1:
358 	flags |= KRB5_STORAGE_PRINCIPAL_WRONG_NUM_COMPONENTS;
359 	flags |= KRB5_STORAGE_PRINCIPAL_NO_NAME_TYPE;
360 	flags |= KRB5_STORAGE_HOST_BYTEORDER;
361 	break;
362     case KRB5_KT_VNO_2:
363 	break;
364     default:
365 	krb5_warnx(context,
366 		   "storage_set_flags called with bad vno (%d)", vno);
367     }
368     krb5_storage_set_flags(sp, flags);
369 }
370 
371 static krb5_error_code
372 fkt_start_seq_get_int(krb5_context context,
373 		      krb5_keytab id,
374 		      int flags,
375 		      int exclusive,
376 		      krb5_kt_cursor *c)
377 {
378     int8_t pvno, tag;
379     krb5_error_code ret;
380     struct fkt_data *d = id->data;
381 
382     c->fd = open (d->filename, flags);
383     if (c->fd < 0) {
384 	ret = errno;
385 	krb5_set_error_message(context, ret,
386 			       N_("keytab %s open failed: %s", ""),
387 			       d->filename, strerror(ret));
388 	return ret;
389     }
390     rk_cloexec(c->fd);
391     ret = _krb5_xlock(context, c->fd, exclusive, d->filename);
392     if (ret) {
393 	close(c->fd);
394 	return ret;
395     }
396     c->sp = krb5_storage_from_fd(c->fd);
397     if (c->sp == NULL) {
398 	_krb5_xunlock(context, c->fd);
399 	close(c->fd);
400 	krb5_set_error_message(context, ENOMEM,
401 			       N_("malloc: out of memory", ""));
402 	return ENOMEM;
403     }
404     krb5_storage_set_eof_code(c->sp, KRB5_KT_END);
405     ret = krb5_ret_int8(c->sp, &pvno);
406     if(ret) {
407 	krb5_storage_free(c->sp);
408 	_krb5_xunlock(context, c->fd);
409 	close(c->fd);
410 	krb5_clear_error_message(context);
411 	return ret;
412     }
413     if(pvno != 5) {
414 	krb5_storage_free(c->sp);
415 	_krb5_xunlock(context, c->fd);
416 	close(c->fd);
417 	krb5_clear_error_message (context);
418 	return KRB5_KEYTAB_BADVNO;
419     }
420     ret = krb5_ret_int8(c->sp, &tag);
421     if (ret) {
422 	krb5_storage_free(c->sp);
423 	_krb5_xunlock(context, c->fd);
424 	close(c->fd);
425 	krb5_clear_error_message(context);
426 	return ret;
427     }
428     id->version = tag;
429     storage_set_flags(context, c->sp, id->version);
430     return 0;
431 }
432 
433 static krb5_error_code KRB5_CALLCONV
434 fkt_start_seq_get(krb5_context context,
435 		  krb5_keytab id,
436 		  krb5_kt_cursor *c)
437 {
438     return fkt_start_seq_get_int(context, id, O_RDONLY | O_BINARY | O_CLOEXEC, 0, c);
439 }
440 
441 static krb5_error_code
442 fkt_next_entry_int(krb5_context context,
443 		   krb5_keytab id,
444 		   krb5_keytab_entry *entry,
445 		   krb5_kt_cursor *cursor,
446 		   off_t *start,
447 		   off_t *end)
448 {
449     struct fkt_data *d = id->data;
450     int32_t len;
451     int ret;
452     int8_t tmp8;
453     int32_t tmp32;
454     uint32_t utmp32;
455     off_t pos, curpos;
456 
457     pos = krb5_storage_seek(cursor->sp, 0, SEEK_CUR);
458 loop:
459     ret = krb5_ret_int32(cursor->sp, &len);
460     if (ret)
461 	return ret;
462     if(len < 0) {
463 	pos = krb5_storage_seek(cursor->sp, -len, SEEK_CUR);
464 	goto loop;
465     }
466     ret = krb5_kt_ret_principal (context, d, cursor->sp, &entry->principal);
467     if (ret)
468 	goto out;
469     ret = krb5_ret_uint32(cursor->sp, &utmp32);
470     entry->timestamp = utmp32;
471     if (ret)
472 	goto out;
473     ret = krb5_ret_int8(cursor->sp, &tmp8);
474     if (ret)
475 	goto out;
476     entry->vno = tmp8;
477     ret = krb5_kt_ret_keyblock (context, d, cursor->sp, &entry->keyblock);
478     if (ret)
479 	goto out;
480     /* there might be a 32 bit kvno here
481      * if it's zero, assume that the 8bit one was right,
482      * otherwise trust the new value */
483     curpos = krb5_storage_seek(cursor->sp, 0, SEEK_CUR);
484     if(len + 4 + pos - curpos >= 4) {
485 	ret = krb5_ret_int32(cursor->sp, &tmp32);
486 	if (ret == 0 && tmp32 != 0)
487 	    entry->vno = tmp32;
488     }
489     /* there might be a flags field here */
490     if(len + 4 + pos - curpos >= 8) {
491 	ret = krb5_ret_uint32(cursor->sp, &utmp32);
492 	if (ret == 0)
493 	    entry->flags = utmp32;
494     } else
495 	entry->flags = 0;
496 
497     entry->aliases = NULL;
498 
499     if(start) *start = pos;
500     if(end) *end = pos + 4 + len;
501  out:
502     krb5_storage_seek(cursor->sp, pos + 4 + len, SEEK_SET);
503     return ret;
504 }
505 
506 static krb5_error_code KRB5_CALLCONV
507 fkt_next_entry(krb5_context context,
508 	       krb5_keytab id,
509 	       krb5_keytab_entry *entry,
510 	       krb5_kt_cursor *cursor)
511 {
512     return fkt_next_entry_int(context, id, entry, cursor, NULL, NULL);
513 }
514 
515 static krb5_error_code KRB5_CALLCONV
516 fkt_end_seq_get(krb5_context context,
517 		krb5_keytab id,
518 		krb5_kt_cursor *cursor)
519 {
520     krb5_storage_free(cursor->sp);
521     _krb5_xunlock(context, cursor->fd);
522     close(cursor->fd);
523     return 0;
524 }
525 
526 static krb5_error_code KRB5_CALLCONV
527 fkt_setup_keytab(krb5_context context,
528 		 krb5_keytab id,
529 		 krb5_storage *sp)
530 {
531     krb5_error_code ret;
532     ret = krb5_store_int8(sp, 5);
533     if(ret)
534 	return ret;
535     if(id->version == 0)
536 	id->version = KRB5_KT_VNO;
537     return krb5_store_int8 (sp, id->version);
538 }
539 
540 static krb5_error_code KRB5_CALLCONV
541 fkt_add_entry(krb5_context context,
542 	      krb5_keytab id,
543 	      krb5_keytab_entry *entry)
544 {
545     int ret;
546     int fd;
547     krb5_storage *sp;
548     struct fkt_data *d = id->data;
549     krb5_data keytab;
550     int32_t len;
551 
552     fd = open (d->filename, O_RDWR | O_BINARY | O_CLOEXEC);
553     if (fd < 0) {
554 	fd = open (d->filename, O_RDWR | O_CREAT | O_EXCL | O_BINARY | O_CLOEXEC, 0600);
555 	if (fd < 0) {
556 	    ret = errno;
557 	    krb5_set_error_message(context, ret,
558 				   N_("open(%s): %s", ""), d->filename,
559 				   strerror(ret));
560 	    return ret;
561 	}
562 	rk_cloexec(fd);
563 
564 	ret = _krb5_xlock(context, fd, 1, d->filename);
565 	if (ret) {
566 	    close(fd);
567 	    return ret;
568 	}
569 	sp = krb5_storage_from_fd(fd);
570 	krb5_storage_set_eof_code(sp, KRB5_KT_END);
571 	ret = fkt_setup_keytab(context, id, sp);
572 	if(ret) {
573 	    goto out;
574 	}
575 	storage_set_flags(context, sp, id->version);
576     } else {
577 	int8_t pvno, tag;
578 
579 	rk_cloexec(fd);
580 
581 	ret = _krb5_xlock(context, fd, 1, d->filename);
582 	if (ret) {
583 	    close(fd);
584 	    return ret;
585 	}
586 	sp = krb5_storage_from_fd(fd);
587 	krb5_storage_set_eof_code(sp, KRB5_KT_END);
588 	ret = krb5_ret_int8(sp, &pvno);
589 	if(ret) {
590 	    /* we probably have a zero byte file, so try to set it up
591                properly */
592 	    ret = fkt_setup_keytab(context, id, sp);
593 	    if(ret) {
594 		krb5_set_error_message(context, ret,
595 				       N_("%s: keytab is corrupted: %s", ""),
596 				       d->filename, strerror(ret));
597 		goto out;
598 	    }
599 	    storage_set_flags(context, sp, id->version);
600 	} else {
601 	    if(pvno != 5) {
602 		ret = KRB5_KEYTAB_BADVNO;
603 		krb5_set_error_message(context, ret,
604 				       N_("Bad version in keytab %s", ""),
605 				       d->filename);
606 		goto out;
607 	    }
608 	    ret = krb5_ret_int8 (sp, &tag);
609 	    if (ret) {
610 		krb5_set_error_message(context, ret,
611 				       N_("failed reading tag from "
612 					  "keytab %s", ""),
613 				       d->filename);
614 		goto out;
615 	    }
616 	    id->version = tag;
617 	    storage_set_flags(context, sp, id->version);
618 	}
619     }
620 
621     {
622 	krb5_storage *emem;
623 	emem = krb5_storage_emem();
624 	if(emem == NULL) {
625 	    ret = ENOMEM;
626 	    krb5_set_error_message(context, ret,
627 				   N_("malloc: out of memory", ""));
628 	    goto out;
629 	}
630 	ret = krb5_kt_store_principal(context, emem, entry->principal);
631 	if(ret) {
632 	    krb5_set_error_message(context, ret,
633 				   N_("Failed storing principal "
634 				      "in keytab %s", ""),
635 				   d->filename);
636 	    krb5_storage_free(emem);
637 	    goto out;
638 	}
639 	ret = krb5_store_int32 (emem, entry->timestamp);
640 	if(ret) {
641 	    krb5_set_error_message(context, ret,
642 				   N_("Failed storing timpstamp "
643 				      "in keytab %s", ""),
644 				   d->filename);
645 	    krb5_storage_free(emem);
646 	    goto out;
647 	}
648 	ret = krb5_store_int8 (emem, entry->vno % 256);
649 	if(ret) {
650 	    krb5_set_error_message(context, ret,
651 				   N_("Failed storing kvno "
652 				      "in keytab %s", ""),
653 				   d->filename);
654 	    krb5_storage_free(emem);
655 	    goto out;
656 	}
657 	ret = krb5_kt_store_keyblock (context, d, emem, &entry->keyblock);
658 	if(ret) {
659 	    krb5_storage_free(emem);
660 	    goto out;
661 	}
662 	if ((d->flags & KRB5_KT_FL_JAVA) == 0) {
663 	    ret = krb5_store_int32 (emem, entry->vno);
664 	    if (ret) {
665 		krb5_set_error_message(context, ret,
666 				       N_("Failed storing extended kvno "
667 					  "in keytab %s", ""),
668 				       d->filename);
669 		krb5_storage_free(emem);
670 		goto out;
671 	    }
672 	    ret = krb5_store_uint32 (emem, entry->flags);
673 	    if (ret) {
674 		krb5_set_error_message(context, ret,
675 				       N_("Failed storing extended kvno "
676 					  "in keytab %s", ""),
677 				       d->filename);
678 		krb5_storage_free(emem);
679 		goto out;
680 	    }
681 	}
682 
683 	ret = krb5_storage_to_data(emem, &keytab);
684 	krb5_storage_free(emem);
685 	if(ret) {
686 	    krb5_set_error_message(context, ret,
687 				   N_("Failed converting keytab entry "
688 				      "to memory block for keytab %s", ""),
689 				   d->filename);
690 	    goto out;
691 	}
692     }
693 
694     while(1) {
695 	ret = krb5_ret_int32(sp, &len);
696 	if(ret == KRB5_KT_END) {
697 	    len = keytab.length;
698 	    break;
699 	}
700 	if(len < 0) {
701 	    len = -len;
702 	    if(len >= (int)keytab.length) {
703 		krb5_storage_seek(sp, -4, SEEK_CUR);
704 		break;
705 	    }
706 	}
707 	krb5_storage_seek(sp, len, SEEK_CUR);
708     }
709     ret = krb5_store_int32(sp, len);
710     if(krb5_storage_write(sp, keytab.data, keytab.length) < 0) {
711 	ret = errno;
712 	krb5_set_error_message(context, ret,
713 			       N_("Failed writing keytab block "
714 				  "in keytab %s: %s", ""),
715 			       d->filename, strerror(ret));
716     }
717     memset(keytab.data, 0, keytab.length);
718     krb5_data_free(&keytab);
719   out:
720     krb5_storage_free(sp);
721     _krb5_xunlock(context, fd);
722     close(fd);
723     return ret;
724 }
725 
726 static krb5_error_code KRB5_CALLCONV
727 fkt_remove_entry(krb5_context context,
728 		 krb5_keytab id,
729 		 krb5_keytab_entry *entry)
730 {
731     krb5_keytab_entry e;
732     krb5_kt_cursor cursor;
733     off_t pos_start, pos_end;
734     int found = 0;
735     krb5_error_code ret;
736 
737     ret = fkt_start_seq_get_int(context, id, O_RDWR | O_BINARY | O_CLOEXEC, 1, &cursor);
738     if(ret != 0)
739 	goto out; /* return other error here? */
740     while(fkt_next_entry_int(context, id, &e, &cursor,
741 			     &pos_start, &pos_end) == 0) {
742 	if(krb5_kt_compare(context, &e, entry->principal,
743 			   entry->vno, entry->keyblock.keytype)) {
744 	    int32_t len;
745 	    unsigned char buf[128];
746 	    found = 1;
747 	    krb5_storage_seek(cursor.sp, pos_start, SEEK_SET);
748 	    len = pos_end - pos_start - 4;
749 	    krb5_store_int32(cursor.sp, -len);
750 	    memset(buf, 0, sizeof(buf));
751 	    while(len > 0) {
752 		krb5_storage_write(cursor.sp, buf,
753 		    min((size_t)len, sizeof(buf)));
754 		len -= min((size_t)len, sizeof(buf));
755 	    }
756 	}
757 	krb5_kt_free_entry(context, &e);
758     }
759     krb5_kt_end_seq_get(context, id, &cursor);
760   out:
761     if (!found) {
762 	krb5_clear_error_message (context);
763 	return KRB5_KT_NOTFOUND;
764     }
765     return 0;
766 }
767 
768 const krb5_kt_ops krb5_fkt_ops = {
769     "FILE",
770     fkt_resolve,
771     fkt_get_name,
772     fkt_close,
773     fkt_destroy,
774     NULL, /* get */
775     fkt_start_seq_get,
776     fkt_next_entry,
777     fkt_end_seq_get,
778     fkt_add_entry,
779     fkt_remove_entry
780 };
781 
782 const krb5_kt_ops krb5_wrfkt_ops = {
783     "WRFILE",
784     fkt_resolve,
785     fkt_get_name,
786     fkt_close,
787     fkt_destroy,
788     NULL, /* get */
789     fkt_start_seq_get,
790     fkt_next_entry,
791     fkt_end_seq_get,
792     fkt_add_entry,
793     fkt_remove_entry
794 };
795 
796 const krb5_kt_ops krb5_javakt_ops = {
797     "JAVA14",
798     fkt_resolve_java14,
799     fkt_get_name,
800     fkt_close,
801     fkt_destroy,
802     NULL, /* get */
803     fkt_start_seq_get,
804     fkt_next_entry,
805     fkt_end_seq_get,
806     fkt_add_entry,
807     fkt_remove_entry
808 };
809