1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2008 Sean C. Farley <scf@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer,
12 *    without modification, immediately at the beginning of the file.
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#include <sys/errno.h>
34#include <sys/stat.h>
35
36#include <ctype.h>
37#include <err.h>
38#include <fcntl.h>
39#include <grp.h>
40#include <inttypes.h>
41#include <libutil.h>
42#include <paths.h>
43#include <stdbool.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <unistd.h>
48
49static int lockfd = -1;
50static char group_dir[PATH_MAX];
51static char group_file[PATH_MAX];
52static char tempname[PATH_MAX];
53static int initialized;
54static size_t grmemlen(const struct group *, const char *, int *);
55static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
56
57/*
58 * Initialize statics
59 */
60int
61gr_init(const char *dir, const char *group)
62{
63
64	if (dir == NULL) {
65		strcpy(group_dir, _PATH_ETC);
66	} else {
67		if (strlen(dir) >= sizeof(group_dir)) {
68			errno = ENAMETOOLONG;
69			return (-1);
70		}
71		strcpy(group_dir, dir);
72	}
73
74	if (group == NULL) {
75		if (dir == NULL) {
76			strcpy(group_file, _PATH_GROUP);
77		} else if (snprintf(group_file, sizeof(group_file), "%s/group",
78			group_dir) > (int)sizeof(group_file)) {
79			errno = ENAMETOOLONG;
80			return (-1);
81		}
82	} else {
83		if (strlen(group) >= sizeof(group_file)) {
84			errno = ENAMETOOLONG;
85			return (-1);
86		}
87		strcpy(group_file, group);
88	}
89
90	initialized = 1;
91	return (0);
92}
93
94/*
95 * Lock the group file
96 */
97int
98gr_lock(void)
99{
100	if (*group_file == '\0')
101		return (-1);
102
103	for (;;) {
104		struct stat st;
105
106		lockfd = flopen(group_file, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
107		if (lockfd == -1) {
108			if (errno == EWOULDBLOCK) {
109				errx(1, "the group file is busy");
110			} else {
111				err(1, "could not lock the group file");
112			}
113		}
114		if (fstat(lockfd, &st) == -1)
115			err(1, "fstat() failed");
116		if (st.st_nlink != 0)
117			break;
118		close(lockfd);
119		lockfd = -1;
120	}
121	return (lockfd);
122}
123
124/*
125 * Create and open a presmuably safe temp file for editing group data
126 */
127int
128gr_tmp(int mfd)
129{
130	char buf[8192];
131	ssize_t nr;
132	const char *p;
133	int tfd;
134
135	if (*group_file == '\0')
136		return (-1);
137	if ((p = strrchr(group_file, '/')))
138		++p;
139	else
140		p = group_file;
141	if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
142		(int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
143		errno = ENAMETOOLONG;
144		return (-1);
145	}
146	if ((tfd = mkostemp(tempname, 0)) == -1)
147		return (-1);
148	if (mfd != -1) {
149		while ((nr = read(mfd, buf, sizeof(buf))) > 0)
150			if (write(tfd, buf, (size_t)nr) != nr)
151				break;
152		if (nr != 0) {
153			unlink(tempname);
154			*tempname = '\0';
155			close(tfd);
156			return (-1);
157		}
158	}
159	return (tfd);
160}
161
162/*
163 * Copy the group file from one descriptor to another, replacing, deleting
164 * or adding a single record on the way.
165 */
166int
167gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
168{
169	char *buf, *end, *line, *p, *q, *r, *tmp;
170	struct group *fgr;
171	const struct group *sgr;
172	size_t len, size;
173	int eof, readlen;
174	char t;
175
176	if (old_gr == NULL && gr == NULL)
177		return(-1);
178
179	sgr = old_gr;
180	/* deleting a group */
181	if (gr == NULL) {
182		line = NULL;
183	} else {
184		if ((line = gr_make(gr)) == NULL)
185			return (-1);
186	}
187
188	/* adding a group */
189	if (sgr == NULL)
190		sgr = gr;
191
192	/* initialize the buffer */
193	if ((buf = malloc(size = 1024)) == NULL)
194		goto err;
195
196	eof = 0;
197	len = 0;
198	p = q = end = buf;
199	for (;;) {
200		/* find the end of the current line */
201		for (p = q; q < end && *q != '\0'; ++q)
202			if (*q == '\n')
203				break;
204
205		/* if we don't have a complete line, fill up the buffer */
206		if (q >= end) {
207			if (eof)
208				break;
209			while ((size_t)(q - p) >= size) {
210				if ((tmp = reallocarray(buf, 2, size)) == NULL) {
211					warnx("group line too long");
212					goto err;
213				}
214				p = tmp + (p - buf);
215				q = tmp + (q - buf);
216				end = tmp + (end - buf);
217				buf = tmp;
218				size = size * 2;
219			}
220			if (p < end) {
221				q = memmove(buf, p, end -p);
222				end -= p - buf;
223			} else {
224				p = q = end = buf;
225			}
226			readlen = read(ffd, end, size - (end - buf));
227			if (readlen == -1)
228				goto err;
229			else
230				len = (size_t)readlen;
231			if (len == 0 && p == buf)
232				break;
233			end += len;
234			len = end - buf;
235			if (len < size) {
236				eof = 1;
237				if (len > 0 && buf[len -1] != '\n')
238					++len, *end++ = '\n';
239			}
240			continue;
241		}
242
243		/* is it a blank line or a comment? */
244		for (r = p; r < q && isspace(*r); ++r)
245			/* nothing */;
246		if (r == q || *r == '#') {
247			/* yep */
248			if (write(tfd, p, q -p + 1) != q - p + 1)
249				goto err;
250			++q;
251			continue;
252		}
253
254		/* is it the one we're looking for? */
255
256		t = *q;
257		*q = '\0';
258
259		fgr = gr_scan(r);
260
261		/* fgr is either a struct group for the current line,
262		 * or NULL if the line is malformed.
263		 */
264
265		*q = t;
266		if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
267			/* nope */
268			if (fgr != NULL)
269				free(fgr);
270			if (write(tfd, p, q - p + 1) != q - p + 1)
271				goto err;
272			++q;
273			continue;
274		}
275		if (old_gr && !gr_equal(fgr, old_gr)) {
276			warnx("entry inconsistent");
277			free(fgr);
278			errno = EINVAL; /* hack */
279			goto err;
280		}
281		free(fgr);
282
283		/* it is, replace or remove it */
284		if (line != NULL) {
285			len = strlen(line);
286			if (write(tfd, line, len) != (int) len)
287				goto err;
288		} else {
289			/* when removed, avoid the \n */
290			q++;
291		}
292		/* we're done, just copy the rest over */
293		for (;;) {
294			if (write(tfd, q, end - q) != end - q)
295				goto err;
296			q = buf;
297			readlen = read(ffd, buf, size);
298			if (readlen == 0)
299				break;
300			else
301				len = (size_t)readlen;
302			if (readlen == -1)
303				goto err;
304			end = buf + len;
305		}
306		goto done;
307	}
308
309	/* if we got here, we didn't find the old entry */
310	if (line == NULL) {
311		errno = ENOENT;
312		goto err;
313	}
314	len = strlen(line);
315	if ((size_t)write(tfd, line, len) != len ||
316	   write(tfd, "\n", 1) != 1)
317		goto err;
318 done:
319	free(line);
320	free(buf);
321	return (0);
322 err:
323	free(line);
324	free(buf);
325	return (-1);
326}
327
328/*
329 * Regenerate the group file
330 */
331int
332gr_mkdb(void)
333{
334	int fd;
335
336	if (chmod(tempname, 0644) != 0)
337		return (-1);
338
339	if (rename(tempname, group_file) != 0)
340		return (-1);
341
342	/*
343	 * Make sure new group file is safe on disk. To improve performance we
344	 * will call fsync() to the directory where file lies
345	 */
346	if ((fd = open(group_dir, O_RDONLY|O_DIRECTORY)) == -1)
347		return (-1);
348
349	if (fsync(fd) != 0) {
350		close(fd);
351		return (-1);
352	}
353
354	close(fd);
355	return(0);
356}
357
358/*
359 * Clean up. Preserves errno for the caller's convenience.
360 */
361void
362gr_fini(void)
363{
364	int serrno;
365
366	if (!initialized)
367		return;
368	initialized = 0;
369	serrno = errno;
370	if (*tempname != '\0') {
371		unlink(tempname);
372		*tempname = '\0';
373	}
374	if (lockfd != -1)
375		close(lockfd);
376	errno = serrno;
377}
378
379/*
380 * Compares two struct group's.
381 */
382int
383gr_equal(const struct group *gr1, const struct group *gr2)
384{
385
386	/* Check that the non-member information is the same. */
387	if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
388		if (gr1->gr_name != gr2->gr_name)
389			return (false);
390	} else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
391		return (false);
392	if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
393		if (gr1->gr_passwd != gr2->gr_passwd)
394			return (false);
395	} else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
396		return (false);
397	if (gr1->gr_gid != gr2->gr_gid)
398		return (false);
399
400	/*
401	 * Check all members in both groups.
402	 * getgrnam can return gr_mem with a pointer to NULL.
403	 * gr_dup and gr_add strip out this superfluous NULL, setting
404	 * gr_mem to NULL for no members.
405	*/
406	if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
407		int i;
408
409		for (i = 0;
410		    gr1->gr_mem[i] != NULL && gr2->gr_mem[i] != NULL; i++) {
411			if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
412				return (false);
413		}
414		if (gr1->gr_mem[i] != NULL || gr2->gr_mem[i] != NULL)
415			return (false);
416	} else if (gr1->gr_mem != NULL && gr1->gr_mem[0] != NULL) {
417		return (false);
418	} else if (gr2->gr_mem != NULL && gr2->gr_mem[0] != NULL) {
419		return (false);
420	}
421
422	return (true);
423}
424
425/*
426 * Make a group line out of a struct group.
427 */
428char *
429gr_make(const struct group *gr)
430{
431	const char *group_line_format = "%s:%s:%ju:";
432	const char *sep;
433	char *line;
434	char *p;
435	size_t line_size;
436	int ndx;
437
438	/* Calculate the length of the group line. */
439	line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
440	    gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
441	if (gr->gr_mem != NULL) {
442		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
443			line_size += strlen(gr->gr_mem[ndx]) + 1;
444		if (ndx > 0)
445			line_size--;
446	}
447
448	/* Create the group line and fill it. */
449	if ((line = p = malloc(line_size)) == NULL)
450		return (NULL);
451	p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
452	    (uintmax_t)gr->gr_gid);
453	if (gr->gr_mem != NULL) {
454		sep = "";
455		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
456			p = stpcpy(p, sep);
457			p = stpcpy(p, gr->gr_mem[ndx]);
458			sep = ",";
459		}
460	}
461
462	return (line);
463}
464
465/*
466 * Duplicate a struct group.
467 */
468struct group *
469gr_dup(const struct group *gr)
470{
471	return (gr_add(gr, NULL));
472}
473/*
474 * Add a new member name to a struct group.
475 */
476struct group *
477gr_add(const struct group *gr, const char *newmember)
478{
479	char *mem;
480	size_t len;
481	int num_mem;
482
483	num_mem = 0;
484	len = grmemlen(gr, newmember, &num_mem);
485	/* Create new group and copy old group into it. */
486	if ((mem = malloc(len)) == NULL)
487		return (NULL);
488	return (grcopy(gr, mem, newmember, num_mem));
489}
490
491/* It is safer to walk the pointers given at gr_mem since there is no
492 * guarantee the gr_mem + strings are contiguous in the given struct group
493 * but compactify the new group into the following form.
494 *
495 * The new struct is laid out like this in memory. The example given is
496 * for a group with two members only.
497 *
498 * {
499 * (char *name)
500 * (char *passwd)
501 * (int gid)
502 * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
503 * gr_mem area
504 * (member1 *)
505 * (member2 *)
506 * (NULL)
507 * (name string)
508 * (passwd string)
509 * (member1 string)
510 * (member2 string)
511 * }
512 */
513/*
514 * Copy the contents of a group plus given name to a preallocated group struct
515 */
516static struct group *
517grcopy(const struct group *gr, char *dst, const char *name, int ndx)
518{
519	int i;
520	struct group *newgr;
521
522	newgr = (struct group *)(void *)dst;	/* avoid alignment warning */
523	dst += sizeof(*newgr);
524	if (ndx != 0) {
525		newgr->gr_mem = (char **)(void *)(dst);	/* avoid alignment warning */
526		dst += (ndx + 1) * sizeof(*newgr->gr_mem);
527	} else
528		newgr->gr_mem = NULL;
529	if (gr->gr_name != NULL) {
530		newgr->gr_name = dst;
531		dst = stpcpy(dst, gr->gr_name) + 1;
532	} else
533		newgr->gr_name = NULL;
534	if (gr->gr_passwd != NULL) {
535		newgr->gr_passwd = dst;
536		dst = stpcpy(dst, gr->gr_passwd) + 1;
537	} else
538		newgr->gr_passwd = NULL;
539	newgr->gr_gid = gr->gr_gid;
540	i = 0;
541	/* Original group struct might have a NULL gr_mem */
542	if (gr->gr_mem != NULL) {
543		for (; gr->gr_mem[i] != NULL; i++) {
544			newgr->gr_mem[i] = dst;
545			dst = stpcpy(dst, gr->gr_mem[i]) + 1;
546		}
547	}
548	/* If name is not NULL, newgr->gr_mem is known to be not NULL */
549	if (name != NULL) {
550		newgr->gr_mem[i++] = dst;
551		dst = stpcpy(dst, name) + 1;
552	}
553	/* if newgr->gr_mem is not NULL add NULL marker */
554	if (newgr->gr_mem != NULL)
555		newgr->gr_mem[i] = NULL;
556
557	return (newgr);
558}
559
560/*
561 *  Calculate length of a struct group + given name
562 */
563static size_t
564grmemlen(const struct group *gr, const char *name, int *num_mem)
565{
566	size_t len;
567	int i;
568
569	if (gr == NULL)
570		return (0);
571	/* Calculate size of the group. */
572	len = sizeof(*gr);
573	if (gr->gr_name != NULL)
574		len += strlen(gr->gr_name) + 1;
575	if (gr->gr_passwd != NULL)
576		len += strlen(gr->gr_passwd) + 1;
577	i = 0;
578	if (gr->gr_mem != NULL) {
579		for (; gr->gr_mem[i] != NULL; i++) {
580			len += strlen(gr->gr_mem[i]) + 1;
581			len += sizeof(*gr->gr_mem);
582		}
583	}
584	if (name != NULL) {
585		i++;
586		len += strlen(name) + 1;
587		len += sizeof(*gr->gr_mem);
588	}
589	/* Allow for NULL pointer */
590	if (i != 0)
591		len += sizeof(*gr->gr_mem);
592	*num_mem = i;
593	return(len);
594}
595
596/*
597 * Scan a line and place it into a group structure.
598 */
599static bool
600__gr_scan(char *line, struct group *gr)
601{
602	char *loc;
603	int ndx;
604
605	/* Assign non-member information to structure. */
606	gr->gr_name = line;
607	if ((loc = strchr(line, ':')) == NULL)
608		return (false);
609	*loc = '\0';
610	gr->gr_passwd = loc + 1;
611	if (*gr->gr_passwd == ':')
612		*gr->gr_passwd = '\0';
613	else {
614		if ((loc = strchr(loc + 1, ':')) == NULL)
615			return (false);
616		*loc = '\0';
617	}
618	if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
619		return (false);
620
621	/* Assign member information to structure. */
622	if ((loc = strchr(loc + 1, ':')) == NULL)
623		return (false);
624	line = loc + 1;
625	gr->gr_mem = NULL;
626	ndx = 0;
627	do {
628		gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
629		    (ndx + 1));
630		if (gr->gr_mem == NULL)
631			return (false);
632
633		/* Skip locations without members (i.e., empty string). */
634		do {
635			gr->gr_mem[ndx] = strsep(&line, ",");
636		} while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
637	} while (gr->gr_mem[ndx++] != NULL);
638
639	return (true);
640}
641
642/*
643 * Create a struct group from a line.
644 */
645struct group *
646gr_scan(const char *line)
647{
648	struct group gr;
649	char *line_copy;
650	struct group *new_gr;
651
652	if ((line_copy = strdup(line)) == NULL)
653		return (NULL);
654	if (!__gr_scan(line_copy, &gr)) {
655		free(line_copy);
656		return (NULL);
657	}
658	new_gr = gr_dup(&gr);
659	free(line_copy);
660	if (gr.gr_mem != NULL)
661		free(gr.gr_mem);
662
663	return (new_gr);
664}
665