gr_util.c revision 243328 
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 243328 2012-11-20 07:22:07Z 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
47struct group_storage {
48	struct group	 gr;
49	char		*members[];
50};
51
52static int lockfd = -1;
53static char group_dir[PATH_MAX];
54static char group_file[PATH_MAX];
55static char tempname[PATH_MAX];
56static int initialized;
57
58static const char group_line_format[] = "%s:%s:%ju:";
59
60/*
61 * Initialize statics
62 */
63int
64gr_init(const char *dir, const char *group)
65{
66
67	if (dir == NULL) {
68		strcpy(group_dir, _PATH_ETC);
69	} else {
70		if (strlen(dir) >= sizeof(group_dir)) {
71			errno = ENAMETOOLONG;
72			return (-1);
73		}
74		strcpy(group_dir, dir);
75	}
76
77	if (group == NULL) {
78		if (dir == NULL) {
79			strcpy(group_file, _PATH_GROUP);
80		} else if (snprintf(group_file, sizeof(group_file), "%s/group",
81			group_dir) > (int)sizeof(group_file)) {
82			errno = ENAMETOOLONG;
83			return (-1);
84		}
85	} else {
86		if (strlen(group) >= sizeof(group_file)) {
87			errno = ENAMETOOLONG;
88			return (-1);
89		}
90		strcpy(group_file, group);
91	}
92
93	initialized = 1;
94	return (0);
95}
96
97/*
98 * Lock the group file
99 */
100int
101gr_lock(void)
102{
103	if (*group_file == '\0')
104		return (-1);
105
106	for (;;) {
107		struct stat st;
108
109		lockfd = open(group_file, O_RDONLY, 0);
110		if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
111			err(1, "%s", group_file);
112		if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
113			if (errno == EWOULDBLOCK) {
114				errx(1, "the group file is busy");
115			} else {
116				err(1, "could not lock the group file: ");
117			}
118		}
119		if (fstat(lockfd, &st) == -1)
120			err(1, "fstat() failed: ");
121		if (st.st_nlink != 0)
122			break;
123		close(lockfd);
124		lockfd = -1;
125	}
126	return (lockfd);
127}
128
129/*
130 * Create and open a presmuably safe temp file for editing group data
131 */
132int
133gr_tmp(int mfd)
134{
135	char buf[8192];
136	ssize_t nr;
137	const char *p;
138	int tfd;
139
140	if (*group_file == '\0')
141		return (-1);
142	if ((p = strrchr(group_file, '/')))
143		++p;
144	else
145		p = group_file;
146	if (snprintf(tempname, sizeof(tempname), "%.*sgroup.XXXXXX",
147		(int)(p - group_file), group_file) >= (int)sizeof(tempname)) {
148		errno = ENAMETOOLONG;
149		return (-1);
150	}
151	if ((tfd = mkstemp(tempname)) == -1)
152		return (-1);
153	if (mfd != -1) {
154		while ((nr = read(mfd, buf, sizeof(buf))) > 0)
155			if (write(tfd, buf, (size_t)nr) != nr)
156				break;
157		if (nr != 0) {
158			unlink(tempname);
159			*tempname = '\0';
160			close(tfd);
161			return (-1);
162		}
163	}
164	return (tfd);
165}
166
167/*
168 * Copy the group file from one descriptor to another, replacing, deleting
169 * or adding a single record on the way.
170 */
171int
172gr_copy(int ffd, int tfd, const struct group *gr, struct group *old_gr)
173{
174	char buf[8192], *end, *line, *p, *q, *r, t;
175	struct group *fgr;
176	const struct group *sgr;
177	size_t len;
178	int eof, readlen;
179
180	sgr = gr;
181	if (gr == NULL) {
182		line = NULL;
183		if (old_gr == NULL)
184			return (-1);
185		sgr = old_gr;
186	} else if ((line = gr_make(gr)) == NULL)
187		return (-1);
188
189	eof = 0;
190	len = 0;
191	p = q = end = buf;
192	for (;;) {
193		/* find the end of the current line */
194		for (p = q; q < end && *q != '\0'; ++q)
195			if (*q == '\n')
196				break;
197
198		/* if we don't have a complete line, fill up the buffer */
199		if (q >= end) {
200			if (eof)
201				break;
202			if ((size_t)(q - p) >= sizeof(buf)) {
203				warnx("group line too long");
204				errno = EINVAL; /* hack */
205				goto err;
206			}
207			if (p < end) {
208				q = memmove(buf, p, end -p);
209				end -= p - buf;
210			} else {
211				p = q = end = buf;
212			}
213			readlen = read(ffd, end, sizeof(buf) - (end -buf));
214			if (readlen == -1)
215				goto err;
216			else
217				len = (size_t)readlen;
218			if (len == 0 && p == buf)
219				break;
220			end += len;
221			len = end - buf;
222			if (len < (ssize_t)sizeof(buf)) {
223				eof = 1;
224				if (len > 0 && buf[len -1] != '\n')
225					++len, *end++ = '\n';
226			}
227			continue;
228		}
229
230		/* is it a blank line or a comment? */
231		for (r = p; r < q && isspace(*r); ++r)
232			/* nothing */;
233		if (r == q || *r == '#') {
234			/* yep */
235			if (write(tfd, p, q -p + 1) != q - p + 1)
236				goto err;
237			++q;
238			continue;
239		}
240
241		/* is it the one we're looking for? */
242
243		t = *q;
244		*q = '\0';
245
246		fgr = gr_scan(r);
247
248		/* fgr is either a struct group for the current line,
249		 * or NULL if the line is malformed.
250		 */
251
252		*q = t;
253		if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
254			/* nope */
255			if (fgr != NULL)
256				free(fgr);
257			if (write(tfd, p, q - p + 1) != q - p + 1)
258				goto err;
259			++q;
260			continue;
261		}
262		if (old_gr && !gr_equal(fgr, old_gr)) {
263			warnx("entry inconsistent");
264			free(fgr);
265			errno = EINVAL; /* hack */
266			goto err;
267		}
268		free(fgr);
269
270		/* it is, replace or remove it */
271		if (line != NULL) {
272			len = strlen(line);
273			if (write(tfd, line, len) != (int) len)
274				goto err;
275		} else {
276			/* when removed, avoid the \n */
277			q++;
278		}
279		/* we're done, just copy the rest over */
280		for (;;) {
281			if (write(tfd, q, end - q) != end - q)
282				goto err;
283			q = buf;
284			readlen = read(ffd, buf, sizeof(buf));
285			if (readlen == 0)
286				break;
287			else
288				len = (size_t)readlen;
289			if (readlen == -1)
290				goto err;
291			end = buf + len;
292		}
293		goto done;
294	}
295
296	/* if we got here, we didn't find the old entry */
297	if (line == NULL) {
298		errno = ENOENT;
299		goto err;
300	}
301	len = strlen(line);
302	if ((size_t)write(tfd, line, len) != len ||
303	   write(tfd, "\n", 1) != 1)
304		goto err;
305 done:
306	if (line != NULL)
307		free(line);
308	return (0);
309 err:
310	if (line != NULL)
311		free(line);
312	return (-1);
313}
314
315/*
316 * Regenerate the group file
317 */
318int
319gr_mkdb(void)
320{
321	int ret;
322
323	ret = rename(tempname, group_file);
324
325	if (ret == 0)
326		chmod(group_file, 0644);
327
328	return (ret);
329}
330
331/*
332 * Clean up. Preserver errno for the caller's convenience.
333 */
334void
335gr_fini(void)
336{
337	int serrno;
338
339	if (!initialized)
340		return;
341	initialized = 0;
342	serrno = errno;
343	if (*tempname != '\0') {
344		unlink(tempname);
345		*tempname = '\0';
346	}
347	if (lockfd != -1)
348		close(lockfd);
349	errno = serrno;
350}
351
352/*
353 * Compares two struct group's.
354 */
355int
356gr_equal(const struct group *gr1, const struct group *gr2)
357{
358	int gr1_ndx;
359	int gr2_ndx;
360	bool found;
361
362	/* Check that the non-member information is the same. */
363	if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
364		if (gr1->gr_name != gr2->gr_name)
365			return (false);
366	} else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
367		return (false);
368	if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
369		if (gr1->gr_passwd != gr2->gr_passwd)
370			return (false);
371	} else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
372		return (false);
373	if (gr1->gr_gid != gr2->gr_gid)
374		return (false);
375
376	/* Check all members in both groups. */
377	if (gr1->gr_mem == NULL || gr2->gr_mem == NULL) {
378		if (gr1->gr_mem != gr2->gr_mem)
379			return (false);
380	} else {
381		for (found = false, gr1_ndx = 0; gr1->gr_mem[gr1_ndx] != NULL;
382		    gr1_ndx++) {
383			for (gr2_ndx = 0; gr2->gr_mem[gr2_ndx] != NULL;
384			    gr2_ndx++)
385				if (strcmp(gr1->gr_mem[gr1_ndx],
386				    gr2->gr_mem[gr2_ndx]) == 0) {
387					found = true;
388					break;
389				}
390			if (!found)
391				return (false);
392		}
393
394		/* Check that group2 does not have more members than group1. */
395		if (gr2->gr_mem[gr1_ndx] != NULL)
396			return (false);
397	}
398
399	return (true);
400}
401
402/*
403 * Make a group line out of a struct group.
404 */
405char *
406gr_make(const struct group *gr)
407{
408	char *line;
409	size_t line_size;
410	int ndx;
411
412	/* Calculate the length of the group line. */
413	line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
414	    gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
415	if (gr->gr_mem != NULL) {
416		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
417			line_size += strlen(gr->gr_mem[ndx]) + 1;
418		if (ndx > 0)
419			line_size--;
420	}
421
422	/* Create the group line and fill it. */
423	if ((line = malloc(line_size)) == NULL)
424		return (NULL);
425	snprintf(line, line_size, group_line_format, gr->gr_name, gr->gr_passwd,
426	    (uintmax_t)gr->gr_gid);
427	if (gr->gr_mem != NULL)
428		for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
429			strcat(line, gr->gr_mem[ndx]);
430			if (gr->gr_mem[ndx + 1] != NULL)
431				strcat(line, ",");
432		}
433
434	return (line);
435}
436
437/*
438 * Duplicate a struct group.
439 */
440struct group *
441gr_dup(const struct group *gr)
442{
443	char *dst;
444	size_t len;
445	struct group_storage *gs;
446	int ndx;
447	int num_mem;
448
449	/* Calculate size of the group. */
450	len = sizeof(*gs);
451	if (gr->gr_name != NULL)
452		len += strlen(gr->gr_name) + 1;
453	if (gr->gr_passwd != NULL)
454		len += strlen(gr->gr_passwd) + 1;
455	if (gr->gr_mem != NULL) {
456		for (num_mem = 0; gr->gr_mem[num_mem] != NULL; num_mem++)
457			len += strlen(gr->gr_mem[num_mem]) + 1;
458		len += (num_mem + 1) * sizeof(*gr->gr_mem);
459	} else
460		num_mem = -1;
461
462	/* Create new group and copy old group into it. */
463	if ((gs = calloc(1, len)) == NULL)
464		return (NULL);
465	dst = (char *)&gs->members[num_mem + 1];
466	if (gr->gr_name != NULL) {
467		gs->gr.gr_name = dst;
468		dst = stpcpy(gs->gr.gr_name, gr->gr_name) + 1;
469	}
470	if (gr->gr_passwd != NULL) {
471		gs->gr.gr_passwd = dst;
472		dst = stpcpy(gs->gr.gr_passwd, gr->gr_passwd) + 1;
473	}
474	gs->gr.gr_gid = gr->gr_gid;
475	if (gr->gr_mem != NULL) {
476		gs->gr.gr_mem = gs->members;
477		for (ndx = 0; ndx < num_mem; ndx++) {
478			gs->gr.gr_mem[ndx] = dst;
479			dst = stpcpy(gs->gr.gr_mem[ndx], gr->gr_mem[ndx]) + 1;
480		}
481		gs->gr.gr_mem[ndx] = NULL;
482	}
483
484	return (&gs->gr);
485}
486
487/*
488 * Scan a line and place it into a group structure.
489 */
490static bool
491__gr_scan(char *line, struct group *gr)
492{
493	char *loc;
494	int ndx;
495
496	/* Assign non-member information to structure. */
497	gr->gr_name = line;
498	if ((loc = strchr(line, ':')) == NULL)
499		return (false);
500	*loc = '\0';
501	gr->gr_passwd = loc + 1;
502	if (*gr->gr_passwd == ':')
503		*gr->gr_passwd = '\0';
504	else {
505		if ((loc = strchr(loc + 1, ':')) == NULL)
506			return (false);
507		*loc = '\0';
508	}
509	if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
510		return (false);
511
512	/* Assign member information to structure. */
513	if ((loc = strchr(loc + 1, ':')) == NULL)
514		return (false);
515	line = loc + 1;
516	gr->gr_mem = NULL;
517	ndx = 0;
518	do {
519		gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
520		    (ndx + 1));
521		if (gr->gr_mem == NULL)
522			return (false);
523
524		/* Skip locations without members (i.e., empty string). */
525		do {
526			gr->gr_mem[ndx] = strsep(&line, ",");
527		} while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
528	} while (gr->gr_mem[ndx++] != NULL);
529
530	return (true);
531}
532
533/*
534 * Create a struct group from a line.
535 */
536struct group *
537gr_scan(const char *line)
538{
539	struct group gr;
540	char *line_copy;
541	struct group *new_gr;
542
543	if ((line_copy = strdup(line)) == NULL)
544		return (NULL);
545	if (!__gr_scan(line_copy, &gr)) {
546		free(line_copy);
547		return (NULL);
548	}
549	new_gr = gr_dup(&gr);
550	free(line_copy);
551	if (gr.gr_mem != NULL)
552		free(gr.gr_mem);
553
554	return (new_gr);
555}
556