1/*-
2 * Copyright (c) 2008 Sean C. Farley <scf@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer,
10 *    without modification, immediately at the beginning of the file.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/param.h>
31#include <sys/errno.h>
32#include <sys/stat.h>
33
34#include <ctype.h>
35#include <err.h>
36#include <fcntl.h>
37#include <grp.h>
38#include <inttypes.h>
39#include <libutil.h>
40#include <paths.h>
41#include <stdbool.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <unistd.h>
46
47static int lockfd = -1;
48static char group_dir[PATH_MAX];
49static char group_file[PATH_MAX];
50static char tempname[PATH_MAX];
51static int initialized;
52static size_t grmemlen(const struct group *, const char *, int *);
53static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
54
55/*
56 * Initialize statics
57 */
58int
59gr_init(const char *dir, const char *group)
60{
61
62	if (dir == NULL) {
63		strcpy(group_dir, _PATH_ETC);
64	} else {
65		if (strlen(dir) >= sizeof(group_dir)) {
66			errno = ENAMETOOLONG;
67			return (-1);
68		}
69		strcpy(group_dir, dir);
70	}
71
72	if (group == NULL) {
73		if (dir == NULL) {
74			strcpy(group_file, _PATH_GROUP);
75		} else if (snprintf(group_file, sizeof(group_file), "%s/group",
76			group_dir) > (int)sizeof(group_file)) {
77			errno = ENAMETOOLONG;
78			return (-1);
79		}
80	} else {
81		if (strlen(group) >= sizeof(group_file)) {
82			errno = ENAMETOOLONG;
83			return (-1);
84		}
85		strcpy(group_file, group);
86	}
87
88	initialized = 1;
89	return (0);
90}
91
92/*
93 * Lock the group file
94 */
95int
96gr_lock(void)
97{
98	if (*group_file == '\0')
99		return (-1);
100
101	for (;;) {
102		struct stat st;
103
104		lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
105		if (lockfd == -1) {
106			if (errno == EWOULDBLOCK) {
107				errx(1, "the group file is busy");
108			} else {
109				err(1, "could not lock the group file: ");
110			}
111		}
112		if (fstat(lockfd, &st) == -1)
113			err(1, "fstat() failed: ");
114		if (st.st_nlink != 0)
115			break;
116		close(lockfd);
117		lockfd = -1;
118	}
119	return (lockfd);
120}
121
122/*
123 * Create and open a presmuably safe temp file for editing group data
124 */
125int
126gr_tmp(int mfd)
127{
128	char buf[8192];
129	ssize_t nr;
130	const char *p;
131	int tfd;
132
133	if (*group_file == '\0')
134		return (-1);
135	if ((p = strrchr(group_file, '/')))
136		++p;
137	else
138		p = group_file;
139	if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
140		(int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
141		errno = ENAMETOOLONG;
142		return (-1);
143	}
144	if ((tfd = mkstemp(tempname)) == -1)
145		return (-1);
146	if (mfd != -1) {
147		while ((nr = read(mfd, buf, sizeof(buf))) > 0)
148			if (write(tfd, buf, (size_t)nr) != nr)
149				break;
150		if (nr != 0) {
151			unlink(tempname);
152			*tempname = '\0';
153			close(tfd);
154			return (-1);
155		}
156	}
157	return (tfd);
158}
159
160/*
161 * Copy the group file from one descriptor to another, replacing, deleting
162 * or adding a single record on the way.
163 */
164int
165gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
166{
167	char buf[8192], *end, *line, *p, *q, *r, t;
168	struct group *fgr;
169	const struct group *sgr;
170	size_t len;
171	int eof, readlen;
172
173	sgr = gr;
174	if (gr == NULL) {
175		line = NULL;
176		if (old_gr == NULL)
177			return (-1);
178		sgr = old_gr;
179	} else if ((line = gr_make(gr)) == NULL)
180		return (-1);
181
182	eof = 0;
183	len = 0;
184	p = q = end = buf;
185	for (;;) {
186		/* find the end of the current line */
187		for (p = q; q < end && *q != '\0'; ++q)
188			if (*q == '\n')
189				break;
190
191		/* if we don't have a complete line, fill up the buffer */
192		if (q >= end) {
193			if (eof)
194				break;
195			if ((size_t)(q - p) >= sizeof(buf)) {
196				warnx("group line too long");
197				errno = EINVAL; /* hack */
198				goto err;
199			}
200			if (p < end) {
201				q = memmove(buf, p, end -p);
202				end -= p - buf;
203			} else {
204				p = q = end = buf;
205			}
206			readlen = read(ffd, end, sizeof(buf) - (end -buf));
207			if (readlen == -1)
208				goto err;
209			else
210				len = (size_t)readlen;
211			if (len == 0 && p == buf)
212				break;
213			end += len;
214			len = end - buf;
215			if (len < (ssize_t)sizeof(buf)) {
216				eof = 1;
217				if (len > 0 && buf[len -1] != '\n')
218					++len, *end++ = '\n';
219			}
220			continue;
221		}
222
223		/* is it a blank line or a comment? */
224		for (r = p; r < q && isspace(*r); ++r)
225			/* nothing */;
226		if (r == q || *r == '#') {
227			/* yep */
228			if (write(tfd, p, q -p + 1) != q - p + 1)
229				goto err;
230			++q;
231			continue;
232		}
233
234		/* is it the one we're looking for? */
235
236		t = *q;
237		*q = '\0';
238
239		fgr = gr_scan(r);
240
241		/* fgr is either a struct group for the current line,
242		 * or NULL if the line is malformed.
243		 */
244
245		*q = t;
246		if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
247			/* nope */
248			if (fgr != NULL)
249				free(fgr);
250			if (write(tfd, p, q - p + 1) != q - p + 1)
251				goto err;
252			++q;
253			continue;
254		}
255		if (old_gr && !gr_equal(fgr, old_gr)) {
256			warnx("entry inconsistent");
257			free(fgr);
258			errno = EINVAL; /* hack */
259			goto err;
260		}
261		free(fgr);
262
263		/* it is, replace or remove it */
264		if (line != NULL) {
265			len = strlen(line);
266			if (write(tfd, line, len) != (int) len)
267				goto err;
268		} else {
269			/* when removed, avoid the \n */
270			q++;
271		}
272		/* we're done, just copy the rest over */
273		for (;;) {
274			if (write(tfd, q, end - q) != end - q)
275				goto err;
276			q = buf;
277			readlen = read(ffd, buf, sizeof(buf));
278			if (readlen == 0)
279				break;
280			else
281				len = (size_t)readlen;
282			if (readlen == -1)
283				goto err;
284			end = buf + len;
285		}
286		goto done;
287	}
288
289	/* if we got here, we didn't find the old entry */
290	if (line == NULL) {
291		errno = ENOENT;
292		goto err;
293	}
294	len = strlen(line);
295	if ((size_t)write(tfd, line, len) != len ||
296	   write(tfd, "\n", 1) != 1)
297		goto err;
298 done:
299	if (line != NULL)
300		free(line);
301	return (0);
302 err:
303	if (line != NULL)
304		free(line);
305	return (-1);
306}
307
308/*
309 * Regenerate the group file
310 */
311int
312gr_mkdb(void)
313{
314	if (chmod(tempname, 0644) != 0)
315		return (-1);
316
317	return (rename(tempname, group_file));
318}
319
320/*
321 * Clean up. Preserves errno for the caller's convenience.
322 */
323void
324gr_fini(void)
325{
326	int serrno;
327
328	if (!initialized)
329		return;
330	initialized = 0;
331	serrno = errno;
332	if (*tempname != '\0') {
333		unlink(tempname);
334		*tempname = '\0';
335	}
336	if (lockfd != -1)
337		close(lockfd);
338	errno = serrno;
339}
340
341/*
342 * Compares two struct group's.
343 */
344int
345gr_equal(const struct group *gr1, const struct group *gr2)
346{
347	int gr1_ndx;
348	int gr2_ndx;
349
350	/* Check that the non-member information is the same. */
351	if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
352		if (gr1->gr_name != gr2->gr_name)
353			return (false);
354	} else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
355		return (false);
356	if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
357		if (gr1->gr_passwd != gr2->gr_passwd)
358			return (false);
359	} else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
360		return (false);
361	if (gr1->gr_gid != gr2->gr_gid)
362		return (false);
363
364	/* Check all members in both groups.
365	 * getgrnam can return gr_mem with a pointer to NULL.
366	 * gr_dup and gr_add strip out this superfluous NULL, setting
367	 * gr_mem to NULL for no members.
368	*/
369	if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
370		int i;
371
372		for (i = 0; gr1->gr_mem[i] != NULL; i++) {
373			if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
374				return (false);
375		}
376	}
377	/* Count number of members in both structs */
378	gr2_ndx = 0;
379	if (gr2->gr_mem != NULL)
380		for(; gr2->gr_mem[gr2_ndx] != NULL; gr2_ndx++)
381			/* empty */;
382	gr1_ndx = 0;
383	if (gr1->gr_mem != NULL)
384		for(; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++)
385			/* empty */;
386	if (gr1_ndx != gr2_ndx)
387		return (false);
388
389	return (true);
390}
391
392/*
393 * Make a group line out of a struct group.
394 */
395char *
396gr_make(const struct group *gr)
397{
398	const char *group_line_format = "%s:%s:%ju:";
399	const char *sep;
400	char *line;
401	char *p;
402	size_t line_size;
403	int ndx;
404
405	/* Calculate the length of the group line. */
406	line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
407	    gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
408	if (gr->gr_mem != NULL) {
409		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
410			line_size += strlen(gr->gr_mem[ndx]) + 1;
411		if (ndx > 0)
412			line_size--;
413	}
414
415	/* Create the group line and fill it. */
416	if ((line = p = malloc(line_size)) == NULL)
417		return (NULL);
418	p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
419	    (uintmax_t)gr->gr_gid);
420	if (gr->gr_mem != NULL) {
421		sep = "";
422		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
423			p = stpcpy(p, sep);
424			p = stpcpy(p, gr->gr_mem[ndx]);
425			sep = ",";
426		}
427	}
428
429	return (line);
430}
431
432/*
433 * Duplicate a struct group.
434 */
435struct group *
436gr_dup(const struct group *gr)
437{
438	return (gr_add(gr, NULL));
439}
440/*
441 * Add a new member name to a struct group.
442 */
443struct group *
444gr_add(const struct group *gr, const char *newmember)
445{
446	char *mem;
447	size_t len;
448	int num_mem;
449
450	num_mem = 0;
451	len = grmemlen(gr, newmember, &num_mem);
452	/* Create new group and copy old group into it. */
453	if ((mem = malloc(len)) == NULL)
454		return (NULL);
455	return (grcopy(gr, mem, newmember, num_mem));
456}
457
458/* It is safer to walk the pointers given at gr_mem since there is no
459 * guarantee the gr_mem + strings are contiguous in the given struct group
460 * but compactify the new group into the following form.
461 *
462 * The new struct is laid out like this in memory. The example given is
463 * for a group with two members only.
464 *
465 * {
466 * (char *name)
467 * (char *passwd)
468 * (int gid)
469 * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
470 * gr_mem area
471 * (member1 *)
472 * (member2 *)
473 * (NULL)
474 * (name string)
475 * (passwd string)
476 * (member1 string)
477 * (member2 string)
478 * }
479 */
480/*
481 * Copy the contents of a group plus given name to a preallocated group struct
482 */
483static struct group *
484grcopy(const struct group *gr, char *dst, const char *name, int ndx)
485{
486	int i;
487	struct group *newgr;
488
489	newgr = (struct group *)(void *)dst;	/* avoid alignment warning */
490	dst += sizeof(*newgr);
491	if (ndx != 0) {
492		newgr->gr_mem = (char **)(void *)(dst);	/* avoid alignment warning */
493		dst += (ndx + 1) * sizeof(*newgr->gr_mem);
494	} else
495		newgr->gr_mem = NULL;
496	if (gr->gr_name != NULL) {
497		newgr->gr_name = dst;
498		dst = stpcpy(dst, gr->gr_name) + 1;
499	} else
500		newgr->gr_name = NULL;
501	if (gr->gr_passwd != NULL) {
502		newgr->gr_passwd = dst;
503		dst = stpcpy(dst, gr->gr_passwd) + 1;
504	} else
505		newgr->gr_passwd = NULL;
506	newgr->gr_gid = gr->gr_gid;
507	i = 0;
508	/* Original group struct might have a NULL gr_mem */
509	if (gr->gr_mem != NULL) {
510		for (; gr->gr_mem[i] != NULL; i++) {
511			newgr->gr_mem[i] = dst;
512			dst = stpcpy(dst, gr->gr_mem[i]) + 1;
513		}
514	}
515	/* If name is not NULL, newgr->gr_mem is known to be not NULL */
516	if (name != NULL) {
517		newgr->gr_mem[i++] = dst;
518		dst = stpcpy(dst, name) + 1;
519	}
520	/* if newgr->gr_mem is not NULL add NULL marker */
521	if (newgr->gr_mem != NULL)
522		newgr->gr_mem[i] = NULL;
523
524	return (newgr);
525}
526
527/*
528 *  Calculate length of a struct group + given name
529 */
530static size_t
531grmemlen(const struct group *gr, const char *name, int *num_mem)
532{
533	size_t len;
534	int i;
535
536	if (gr == NULL)
537		return (0);
538	/* Calculate size of the group. */
539	len = sizeof(*gr);
540	if (gr->gr_name != NULL)
541		len += strlen(gr->gr_name) + 1;
542	if (gr->gr_passwd != NULL)
543		len += strlen(gr->gr_passwd) + 1;
544	i = 0;
545	if (gr->gr_mem != NULL) {
546		for (; gr->gr_mem[i] != NULL; i++) {
547			len += strlen(gr->gr_mem[i]) + 1;
548			len += sizeof(*gr->gr_mem);
549		}
550	}
551	if (name != NULL) {
552		i++;
553		len += strlen(name) + 1;
554		len += sizeof(*gr->gr_mem);
555	}
556	/* Allow for NULL pointer */
557	if (i != 0)
558		len += sizeof(*gr->gr_mem);
559	*num_mem = i;
560	return(len);
561}
562
563/*
564 * Scan a line and place it into a group structure.
565 */
566static bool
567__gr_scan(char *line, struct group *gr)
568{
569	char *loc;
570	int ndx;
571
572	/* Assign non-member information to structure. */
573	gr->gr_name = line;
574	if ((loc = strchr(line, ':')) == NULL)
575		return (false);
576	*loc = '\0';
577	gr->gr_passwd = loc + 1;
578	if (*gr->gr_passwd == ':')
579		*gr->gr_passwd = '\0';
580	else {
581		if ((loc = strchr(loc + 1, ':')) == NULL)
582			return (false);
583		*loc = '\0';
584	}
585	if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
586		return (false);
587
588	/* Assign member information to structure. */
589	if ((loc = strchr(loc + 1, ':')) == NULL)
590		return (false);
591	line = loc + 1;
592	gr->gr_mem = NULL;
593	ndx = 0;
594	do {
595		gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
596		    (ndx + 1));
597		if (gr->gr_mem == NULL)
598			return (false);
599
600		/* Skip locations without members (i.e., empty string). */
601		do {
602			gr->gr_mem[ndx] = strsep(&line, ",");
603		} while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
604	} while (gr->gr_mem[ndx++] != NULL);
605
606	return (true);
607}
608
609/*
610 * Create a struct group from a line.
611 */
612struct group *
613gr_scan(const char *line)
614{
615	struct group gr;
616	char *line_copy;
617	struct group *new_gr;
618
619	if ((line_copy = strdup(line)) == NULL)
620		return (NULL);
621	if (!__gr_scan(line_copy, &gr)) {
622		free(line_copy);
623		return (NULL);
624	}
625	new_gr = gr_dup(&gr);
626	free(line_copy);
627	if (gr.gr_mem != NULL)
628		free(gr.gr_mem);
629
630	return (new_gr);
631}
632