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