ugidfw.c revision 101206 
1/*-
2 * Copyright (c) 2002 Networks Associates Technology, Inc.
3 * All rights reserved.
4 *
5 * This software was developed for the FreeBSD Project by NAI Labs, the
6 * Security Research Division of Network Associates, Inc. under
7 * DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA
8 * CHATS research program.
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 * 3. The names of the authors may not be used to endorse or promote
19 *    products derived from this software without specific prior written
20 *    permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * $FreeBSD: head/lib/libugidfw/ugidfw.c 101206 2002-08-02 07:07:35Z rwatson $
35 */
36#include <sys/param.h>
37#include <sys/errno.h>
38#include <sys/time.h>
39#include <sys/sysctl.h>
40#include <sys/vnode.h>
41
42#include <security/mac_bsdextended/mac_bsdextended.h>
43
44#include <grp.h>
45#include <pwd.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49
50#include <ugidfw.h>
51
52/*
53 * Text format for rules: rules contain subjectand object elements, mode.
54 * Each element takes the form "[not] [uid number] [gid number]".
55 * The total form is "subject [element] object [element] mode [mode]".
56 * At least * one of a uid or gid entry must be present; both may also be
57 * present.
58 */
59
60#define	MIB	"security.mac.bsdextended"
61
62int
63bsde_rule_to_string(struct mac_bsdextended_rule *rule, char *buf, size_t buflen)
64{
65	struct group *grp;
66	struct passwd *pwd;
67	char *cur;
68	size_t left, len;
69	int anymode, unknownmode, truncated;
70
71	cur = buf;
72	left = buflen;
73	truncated = 0;
74
75	if (rule->mbr_subject.mbi_flags & (MBI_UID_DEFINED |
76	    MBI_GID_DEFINED)) {
77		len = snprintf(cur, left, "subject ");
78		if (len < 0 || len > left)
79			goto truncated;
80		left -= len;
81		cur += len;
82
83		if (rule->mbr_subject.mbi_flags & MBI_NEGATED) {
84			len = snprintf(cur, left, "not ");
85			if (len < 0 || len > left)
86				goto truncated;
87			left -= len;
88			cur += len;
89		}
90		if (rule->mbr_subject.mbi_flags & MBI_UID_DEFINED) {
91			pwd = getpwuid(rule->mbr_subject.mbi_uid);
92			if (pwd != NULL) {
93				len = snprintf(cur, left, "uid %s ",
94				    pwd->pw_name);
95				if (len < 0 || len > left)
96					goto truncated;
97				left -= len;
98				cur += len;
99			} else {
100				len = snprintf(cur, left, "uid %u ",
101				    rule->mbr_subject.mbi_uid);
102				if (len < 0 || len > left)
103					goto truncated;
104				left -= len;
105				cur += len;
106			}
107		}
108		if (rule->mbr_subject.mbi_flags & MBI_GID_DEFINED) {
109			grp = getgrgid(rule->mbr_subject.mbi_gid);
110			if (grp != NULL) {
111				len = snprintf(cur, left, "gid %s ",
112				    grp->gr_name);
113				if (len < 0 || len > left)
114					goto truncated;
115				left -= len;
116				cur += len;
117			} else {
118				len = snprintf(cur, left, "gid %u ",
119				    rule->mbr_subject.mbi_gid);
120				if (len < 0 || len > left)
121					goto truncated;
122				left -= len;
123				cur += len;
124			}
125		}
126	}
127	if (rule->mbr_object.mbi_flags & (MBI_UID_DEFINED |
128	    MBI_GID_DEFINED)) {
129		len = snprintf(cur, left, "object ");
130		if (len < 0 || len > left)
131			goto truncated;
132		left -= len;
133		cur += len;
134
135		if (rule->mbr_object.mbi_flags & MBI_NEGATED) {
136			len = snprintf(cur, left, "not ");
137			if (len < 0 || len > left)
138				goto truncated;
139			left -= len;
140			cur += len;
141		}
142		if (rule->mbr_object.mbi_flags & MBI_UID_DEFINED) {
143			pwd = getpwuid(rule->mbr_object.mbi_uid);
144			if (pwd != NULL) {
145				len = snprintf(cur, left, "uid %s ",
146				    pwd->pw_name);
147				if (len < 0 || len > left)
148					goto truncated;
149				left -= len;
150				cur += len;
151			} else {
152				len = snprintf(cur, left, "uid %u ",
153				    rule->mbr_object.mbi_uid);
154				left -= len;
155				cur += len;
156			}
157		}
158		if (rule->mbr_object.mbi_flags & MBI_GID_DEFINED) {
159			grp = getgrgid(rule->mbr_object.mbi_gid);
160			if (grp != NULL) {
161				len = snprintf(cur, left, "gid %s ",
162				    grp->gr_name);
163				if (len < 0 || len > left)
164					goto truncated;
165				left -= len;
166				cur += len;
167			} else {
168				len = snprintf(cur, left, "gid %u ",
169				    rule->mbr_object.mbi_gid);
170				if (len < 0 || len > left)
171					goto truncated;
172				left -= len;
173				cur += len;
174			}
175		}
176	}
177
178	len = snprintf(cur, left, "mode ");
179	if (len < 0 || len > left)
180		goto truncated;
181	left -= len;
182	cur += len;
183
184	anymode = (rule->mbr_mode & VALLPERM);
185	unknownmode = (rule->mbr_mode & ~VALLPERM);
186
187	if (rule->mbr_mode & VADMIN) {
188		len = snprintf(cur, left, "a");
189		if (len < 0 || len > left)
190			goto truncated;
191
192		left -= len;
193		cur += len;
194	}
195	if (rule->mbr_mode & VREAD) {
196		len = snprintf(cur, left, "r");
197		if (len < 0 || len > left)
198			goto truncated;
199
200		left -= len;
201		cur += len;
202	}
203	if (rule->mbr_mode & VSTAT) {
204		len = snprintf(cur, left, "s");
205		if (len < 0 || len > left)
206			goto truncated;
207
208		left -= len;
209		cur += len;
210	}
211	if (rule->mbr_mode & VWRITE) {
212		len = snprintf(cur, left, "w");
213		if (len < 0 || len > left)
214			goto truncated;
215
216		left -= len;
217		cur += len;
218	}
219	if (rule->mbr_mode & VEXEC) {
220		len = snprintf(cur, left, "x");
221		if (len < 0 || len > left)
222			goto truncated;
223
224		left -= len;
225		cur += len;
226	}
227	if (!anymode) {
228		len = snprintf(cur, left, "n");
229		if (len < 0 || len > left)
230			goto truncated;
231
232		left -= len;
233		cur += len;
234	}
235	if (unknownmode) {
236		len = snprintf(cur, left, "?");
237		if (len < 0 || len > left)
238			goto truncated;
239
240		left -= len;
241		cur += len;
242	}
243
244	return (0);
245
246truncated:
247	return (-1);
248}
249
250int
251bsde_parse_identity(int argc, char *argv[],
252    struct mac_bsdextended_identity *identity, size_t buflen, char *errstr)
253{
254	struct group *grp;
255	struct passwd *pwd;
256	int uid_seen, gid_seen, not_seen;
257	int current;
258	char *endp;
259	long value;
260	uid_t uid;
261	gid_t gid;
262	size_t len;
263
264	if (argc == 0) {
265		len = snprintf(errstr, buflen, "Identity must not be empty");
266		return (-1);
267	}
268
269	current = 0;
270
271	/* First element might be "not". */
272	if (strcmp("not", argv[0]) == 0) {
273		not_seen = 1;
274		current++;
275	} else
276		not_seen = 0;
277
278	if (current >= argc) {
279		len = snprintf(errstr, buflen, "Identity short");
280		return (-1);
281	}
282
283	uid_seen = 0;
284	uid = 0;
285	gid_seen = 0;
286	gid = 0;
287
288	/* First phrase: uid [uid] or gid[gid]. */
289	if (strcmp("uid", argv[current]) == 0) {
290		if (current + 2 > argc) {
291			len = snprintf(errstr, buflen, "uid short");
292			return (-1);
293		}
294		pwd = getpwnam(argv[current+1]);
295		if (pwd != NULL)
296			uid = pwd->pw_uid;
297		else {
298			value = strtol(argv[current+1], &endp, 10);
299			if (*endp != '\0') {
300				len = snprintf(errstr, buflen,
301				    "invalid uid: '%s'",
302				    argv[current+1]);
303				return (-1);
304			}
305			uid = value;
306		}
307		uid_seen = 1;
308		current += 2;
309	} else if (strcmp("gid", argv[current]) == 0) {
310		if (current + 2 > argc) {
311			len = snprintf(errstr, buflen, "gid short");
312			return (-1);
313		}
314		grp = getgrnam(argv[current+1]);
315		if (grp != NULL)
316			gid = grp->gr_gid;
317		else {
318			value = strtol(argv[current+1], &endp, 10);
319			if (*endp != '\0') {
320				len = snprintf(errstr, buflen,
321				    "invalid gid: '%s'",
322				    argv[current+1]);
323				return (-1);
324			}
325			gid = value;
326		}
327		gid_seen = 1;
328		current += 2;
329	} else {
330		len = snprintf(errstr, buflen, "'%s' not expected",
331		    argv[current]);
332		return (-1);
333	}
334
335	/* Onto optional second phrase. */
336	if (current + 1 < argc) {
337		/* Second phrase: uid [uid] or gid [gid], but not a repeat. */
338		if (strcmp("uid", argv[current]) == 0) {
339			if (uid_seen) {
340				len = snprintf(errstr, buflen,
341				    "Only one uid permitted per identity clause");
342				return (-1);
343			}
344			if (current + 2 > argc) {
345				len = snprintf(errstr, buflen, "uid short");
346				return (-1);
347			}
348			value = strtol(argv[current+1], &endp, 10);
349			if (*endp != '\0') {
350				len = snprintf(errstr, buflen, "invalid uid: '%s'",
351				    argv[current+1]);
352				return (-1);
353			}
354			uid = value;
355			uid_seen = 1;
356			current += 2;
357		} else if (strcmp("gid", argv[current]) == 0) {
358			if (gid_seen) {
359				len = snprintf(errstr, buflen,
360				    "Only one gid permitted per identity clause");
361				return (-1);
362			}
363			if (current + 2 > argc) {
364				len = snprintf(errstr, buflen, "gid short");
365				return (-1);
366			}
367			value = strtol(argv[current+1], &endp, 10);
368			if (*endp != '\0') {
369				len = snprintf(errstr, buflen, "invalid gid: '%s'",
370				    argv[current+1]);
371				return (-1);
372			}
373			gid = value;
374			gid_seen = 1;
375			current += 2;
376		} else {
377			len = snprintf(errstr, buflen, "'%s' not expected",
378			    argv[current]);
379			return (-1);
380		}
381	}
382
383	if (current +1 < argc) {
384		len = snprintf(errstr, buflen, "'%s' not expected",
385		    argv[current]);
386		return (-1);
387	}
388
389	/* Fill out the identity. */
390	identity->mbi_flags = 0;
391
392	if (not_seen)
393		identity->mbi_flags |= MBI_NEGATED;
394
395	if (uid_seen) {
396		identity->mbi_flags |= MBI_UID_DEFINED;
397		identity->mbi_uid = uid;
398	} else
399		identity->mbi_uid = 0;
400
401	if (gid_seen) {
402		identity->mbi_flags |= MBI_GID_DEFINED;
403		identity->mbi_gid = gid;
404	} else
405		identity->mbi_gid = 0;
406
407	return (0);
408}
409
410int
411bsde_parse_mode(int argc, char *argv[], mode_t *mode, size_t buflen,
412    char *errstr)
413{
414	size_t len;
415	int i;
416
417	if (argc == 0) {
418		len = snprintf(errstr, buflen, "mode expects mode value");
419		return (-1);
420	}
421
422	if (argc != 1) {
423		len = snprintf(errstr, buflen, "'%s' unexpected", argv[1]);
424		return (-1);
425	}
426
427	*mode = 0;
428	for (i = 0; i < strlen(argv[0]); i++) {
429		switch (argv[0][i]) {
430		case 'a':
431			*mode |= VADMIN;
432			break;
433		case 'r':
434			*mode |= VREAD;
435			break;
436		case 's':
437			*mode |= VSTAT;
438			break;
439		case 'w':
440			*mode |= VWRITE;
441			break;
442		case 'x':
443			*mode |= VEXEC;
444			break;
445		case 'n':
446			/* ignore */
447			break;
448		default:
449			len = snprintf(errstr, buflen, "Unknown mode letter: %c",
450			    argv[0][i]);
451			return (-1);
452		}
453	}
454
455	return (0);
456}
457
458int
459bsde_parse_rule(int argc, char *argv[], struct mac_bsdextended_rule *rule,
460    size_t buflen, char *errstr)
461{
462	int subject, subject_elements, subject_elements_length;
463	int object, object_elements, object_elements_length;
464	int mode, mode_elements, mode_elements_length;
465	int error, i;
466	size_t len;
467
468	bzero(rule, sizeof(*rule));
469
470	if (argc < 1) {
471		len = snprintf(errstr, buflen, "Rule must begin with subject");
472		return (-1);
473	}
474
475	if (strcmp(argv[0], "subject") != 0) {
476		len = snprintf(errstr, buflen, "Rule must begin with subject");
477		return (-1);
478	}
479	subject = 0;
480	subject_elements = 1;
481
482	/* Search forward for object. */
483
484	object = -1;
485	for (i = 1; i < argc; i++)
486		if (strcmp(argv[i], "object") == 0)
487			object = i;
488
489	if (object == -1) {
490		len = snprintf(errstr, buflen, "Rule must contain an object");
491		return (-1);
492	}
493
494	/* Search forward for mode. */
495	mode = -1;
496	for (i = object; i < argc; i++)
497		if (strcmp(argv[i], "mode") == 0)
498			mode = i;
499
500	if (mode == -1) {
501		len = snprintf(errstr, buflen, "Rule must contain mode");
502		return (-1);
503	}
504
505	subject_elements_length = object - subject - 1;
506	object_elements = object + 1;
507	object_elements_length = mode - object_elements;
508	mode_elements = mode + 1;
509	mode_elements_length = argc - mode_elements;
510
511	error = bsde_parse_identity(subject_elements_length,
512	    argv + subject_elements, &rule->mbr_subject, buflen, errstr);
513	if (error)
514		return (-1);
515
516	error = bsde_parse_identity(object_elements_length,
517	    argv + object_elements, &rule->mbr_object, buflen, errstr);
518	if (error)
519		return (-1);
520
521	error = bsde_parse_mode(mode_elements_length, argv + mode_elements,
522	    &rule->mbr_mode, buflen, errstr);
523	if (error)
524		return (-1);
525
526	return (0);
527}
528
529int
530bsde_parse_rule_string(const char *string, struct mac_bsdextended_rule *rule,
531    size_t buflen, char *errstr)
532{
533	char *stringdup, *stringp, *argv[20], **ap;
534	int argc, error;
535
536	stringp = stringdup = strdup(string);
537	while (*stringp == ' ' || *stringp == '\t')
538		stringp++;
539
540	argc = 0;
541	for (ap = argv; (*ap = strsep(&stringp, " \t")) != NULL;) {
542		argc++;
543		if (**ap != '\0')
544			if (++ap >= &argv[20])
545				break;
546	}
547
548	error = bsde_parse_rule(argc, argv, rule, buflen, errstr);
549
550	free(stringdup);
551
552	return (error);
553}
554
555int
556bsde_get_mib(const char *string, int *name, int *namelen)
557{
558	int error, len;
559
560	len = *namelen;
561	error = sysctlnametomib(string, name, &len);
562	if (error)
563		return (error);
564
565	*namelen = len;
566	return (0);
567}
568
569int
570bsde_get_rule_count(size_t buflen, char *errstr)
571{
572	size_t len;
573	int error;
574	int rule_count;
575
576	len = sizeof(rule_count);
577	error = sysctlbyname(MIB ".rule_count", &rule_count, &len, NULL, NULL);
578	if (error) {
579		len = snprintf(errstr, buflen, strerror(errno));
580		return (-1);
581	}
582	if (len != sizeof(rule_count)) {
583		len = snprintf(errstr, buflen, "Data error in %s.rule_count",
584		    MIB);
585		return (-1);
586	}
587
588	return (rule_count);
589}
590
591int
592bsde_get_rule_slots(size_t buflen, char *errstr)
593{
594	size_t len;
595	int error;
596	int rule_slots;
597
598	len = sizeof(rule_slots);
599	error = sysctlbyname(MIB ".rule_slots", &rule_slots, &len, NULL,
600	    NULL);
601	if (error) {
602		len = snprintf(errstr, buflen, strerror(errno));
603		return (-1);
604	}
605	if (len != sizeof(rule_slots)) {
606		len = snprintf(errstr, buflen, "Data error in %s.rule_slots",
607		    MIB);
608		return (-1);
609	}
610
611	return (rule_slots);
612}
613
614/*
615 * Returns 0 for success;
616 * Returns -1 for failure;
617 * Returns -2 for not present
618 */
619int
620bsde_get_rule(int rulenum, struct mac_bsdextended_rule *rule, size_t errlen,
621    char *errstr)
622{
623	int name[10];
624	size_t len, size;
625	int error;
626
627	len = 10;
628	error = bsde_get_mib(MIB ".rules", name, &len);
629	if (error) {
630		len = snprintf(errstr, errlen, "%s: %s", MIB ".rules",
631		    strerror(errno));
632		return (-1);
633	}
634
635	size = sizeof(*rule);
636	name[len] = rulenum;
637	len++;
638	error = sysctl(name, len, rule, &size, NULL, 0);
639	if (error  == -1 && errno == ENOENT)
640		return (-2);
641	if (error) {
642		len = snprintf(errstr, errlen, "%s.%d: %s", MIB ".rules",
643		    rulenum, strerror(errno));
644		return (-1);
645	} else if (size != sizeof(*rule)) {
646		len = snprintf(errstr, errlen, "Data error in %s.%d: %s",
647		    MIB ".rules", rulenum, strerror(errno));
648		return (-1);
649	}
650
651	return (0);
652}
653
654int
655bsde_delete_rule(int rulenum, size_t buflen, char *errstr)
656{
657	struct mac_bsdextended_rule rule;
658	int name[10];
659	size_t len, size;
660	int error;
661
662	len = 10;
663	error = bsde_get_mib(MIB ".rules", name, &len);
664	if (error) {
665		len = snprintf(errstr, buflen, "%s: %s", MIB ".rules",
666		    strerror(errno));
667		return (-1);
668	}
669
670	name[len] = rulenum;
671	len++;
672
673	size = sizeof(rule);
674	error = sysctl(name, len, NULL, NULL, &rule, 0);
675	if (error) {
676		len = snprintf(errstr, buflen, "%s.%d: %s", MIB ".rules",
677		    rulenum, strerror(errno));
678		return (-1);
679	}
680
681	return (0);
682}
683
684int
685bsde_set_rule(int rulenum, struct mac_bsdextended_rule *rule, size_t buflen,
686    char *errstr)
687{
688	int name[10];
689	size_t len, size;
690	int error;
691
692	len = 10;
693	error = bsde_get_mib(MIB ".rules", name, &len);
694	if (error) {
695		len = snprintf(errstr, buflen, "%s: %s", MIB ".rules",
696		    strerror(errno));
697		return (-1);
698	}
699
700	name[len] = rulenum;
701	len++;
702
703	size = sizeof(*rule);
704	error = sysctl(name, len, NULL, NULL, rule, size);
705	if (error) {
706		len = snprintf(errstr, buflen, "%s.%d: %s", MIB ".rules",
707		    rulenum, strerror(errno));
708		return (-1);
709	}
710
711	return (0);
712}
713