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 248102 2013-03-09 13:30:06Z db $");
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}