gr_util.c revision 244742 
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: head/lib/libutil/gr_util.c 244742 2012-12-27 19:33:43Z bapt $");
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;
52
53static const char group_line_format[] = "%s:%s:%ju:";
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, 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. Preserver 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	bool found;
350
351	/* Check that the non-member information is the same. */
352	if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
353		if (gr1->gr_name != gr2->gr_name)
354			return (false);
355	} else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
356		return (false);
357	if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
358		if (gr1->gr_passwd != gr2->gr_passwd)
359			return (false);
360	} else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
361		return (false);
362	if (gr1->gr_gid != gr2->gr_gid)
363		return (false);
364
365	/* Check all members in both groups. */
366	if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
367		if (gr1->gr_mem != gr2->gr_mem)
368			return (false);
369	} else {
370		for (found = false, gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL;
371		    gr1_ndx++) {
372			for (gr2_ndx = 0; gr2->gr_mem[gr2_ndx] != NULL;
373			    gr2_ndx++)
374				if (strcmp(gr1->gr_mem[gr1_ndx],
375				    gr2->gr_mem[gr2_ndx]) == 0) {
376					found = true;
377					break;
378				}
379			if (!found)
380				return (false);
381		}
382
383		/* Check that group2 does not have more members than group1. */
384		if (gr2->gr_mem[gr1_ndx] != NULL)
385			return (false);
386	}
387
388	return (true);
389}
390
391/*
392 * Make a group line out of a struct group.
393 */
394char *
395gr_make(const struct group *gr)
396{
397	char *line;
398	size_t line_size;
399	int ndx;
400
401	/* Calculate the length of the group line. */
402	line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
403	    gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
404	if (gr->gr_mem != NULL) {
405		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
406			line_size += strlen(gr->gr_mem[ndx]) + 1;
407		if (ndx > 0)
408			line_size--;
409	}
410
411	/* Create the group line and fill it. */
412	if ((line = malloc(line_size)) == NULL)
413		return (NULL);
414	snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
415	    (uintmax_t)gr->gr_gid);
416	if (gr->gr_mem != NULL)
417		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
418			strcat(line, gr->gr_mem[ndx]);
419			if (gr->gr_mem[ndx + 1] != NULL)
420				strcat(line, ",");
421		}
422
423	return (line);
424}
425
426/*
427 * Duplicate a struct group.
428 */
429struct group *
430gr_dup(const struct group *gr)
431{
432	struct group *newgr;
433	char *dst;
434	size_t len;
435	int ndx;
436	int num_mem;
437
438	/* Calculate size of the group. */
439	len = sizeof(*newgr);
440	if (gr->gr_name != NULL)
441		len += strlen(gr->gr_name) + 1;
442	if (gr->gr_passwd != NULL)
443		len += strlen(gr->gr_passwd) + 1;
444	if (gr->gr_mem != NULL) {
445		for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
446			len += strlen(gr->gr_mem[num_mem]) + 1;
447		len += (num_mem + 1) * sizeof(*gr->gr_mem);
448	} else
449		num_mem = -1;
450	/* Create new group and copy old group into it. */
451	if ((newgr = malloc(len)) == NULL)
452		return (NULL);
453	/* point new gr_mem to end of struct + 1 */
454	if (gr->gr_mem != NULL)
455		newgr->gr_mem = (char **)newgr + sizeof(struct group);
456	else
457		newgr->gr_mem = NULL;
458	/* point dst after the end of all the gr_mem pointers in newgr */
459	dst = (char *)newgr + sizeof(struct group) +
460	    (num_mem + 1) * sizeof(*gr->gr_mem);
461	if (gr->gr_name != NULL) {
462		newgr->gr_name = dst;
463		dst = stpcpy(dst, gr->gr_name) + 1;
464	}
465	if (gr->gr_passwd != NULL) {
466		newgr->gr_passwd = dst;
467		dst = stpcpy(dst, gr->gr_passwd) + 1;
468	}
469	newgr->gr_gid = gr->gr_gid;
470	if (gr->gr_mem != NULL) {
471		for (ndx = 0; ndx < num_mem; ndx++) {
472			newgr->gr_mem[ndx] = dst;
473			dst = stpcpy(dst, gr->gr_mem[ndx]) + 1;
474		}
475		newgr->gr_mem[ndx] = NULL;
476	}
477	return (newgr);
478}
479
480/*
481 * Add a new member name to a struct group.
482 */
483struct group *
484gr_add(struct group *gr, char *newmember)
485{
486	size_t mlen;
487	int num_mem=0;
488	char **members;
489	struct group *newgr;
490
491	if (newmember == NULL)
492		return(gr_dup(gr));
493
494	if (gr->gr_mem != NULL) {
495		for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++) {
496			if (strcmp(gr->gr_mem[num_mem], newmember) == 0) {
497				errno = EEXIST;
498				return (NULL);
499			}
500		}
501	}
502	/* Allocate enough for current pointers + 1 more and NULL marker */
503	mlen = (num_mem + 2) * sizeof(*gr->gr_mem);
504	if ((members = malloc(mlen)) == NULL) {
505		errno = ENOMEM;
506		return (NULL);
507	}
508	memcpy(members, gr->gr_mem, num_mem * sizeof(*gr->gr_mem));
509	members[num_mem++] = newmember;
510	members[num_mem] = NULL;
511	gr->gr_mem = members;
512	newgr = gr_dup(gr);
513	if (newgr == NULL)
514		errno = ENOMEM;
515	free(members);
516	return (newgr);
517}
518
519/*
520 * Scan a line and place it into a group structure.
521 */
522static bool
523__gr_scan(char *line, struct group *gr)
524{
525	char *loc;
526	int ndx;
527
528	/* Assign non-member information to structure. */
529	gr->gr_name = line;
530	if ((loc = strchr(line, ':')) == NULL)
531		return (false);
532	*loc = '\0';
533	gr->gr_passwd = loc + 1;
534	if (*gr->gr_passwd == ':')
535		*gr->gr_passwd = '\0';
536	else {
537		if ((loc = strchr(loc + 1, ':')) == NULL)
538			return (false);
539		*loc = '\0';
540	}
541	if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
542		return (false);
543
544	/* Assign member information to structure. */
545	if ((loc = strchr(loc + 1, ':')) == NULL)
546		return (false);
547	line = loc + 1;
548	gr->gr_mem = NULL;
549	ndx = 0;
550	do {
551		gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
552		    (ndx + 1));
553		if (gr->gr_mem == NULL)
554			return (false);
555
556		/* Skip locations without members (i.e., empty string). */
557		do {
558			gr->gr_mem[ndx] = strsep(&line, ",");
559		} while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
560	} while (gr->gr_mem[ndx++] != NULL);
561
562	return (true);
563}
564
565/*
566 * Create a struct group from a line.
567 */
568struct group *
569gr_scan(const char *line)
570{
571	struct group gr;
572	char *line_copy;
573	struct group *new_gr;
574
575	if ((line_copy = strdup(line)) == NULL)
576		return (NULL);
577	if (!__gr_scan(line_copy, &gr)) {
578		free(line_copy);
579		return (NULL);
580	}
581	new_gr = gr_dup(&gr);
582	free(line_copy);
583	if (gr.gr_mem != NULL)
584		free(gr.gr_mem);
585
586	return (new_gr);
587}
588