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
46 static int lockfd = -1;
47 static char group_dir[PATH_MAX];
48 static char group_file[PATH_MAX];
49 static char tempname[PATH_MAX];
50 static int initialized;
51 static size_t grmemlen(const struct group *, const char *, int *);
52 static struct group *grcopy(const struct group *gr, char *mem, const char *, int ndx);
53
54 /*
55 * Initialize statics
56 */
57 int
gr_init(const char * dir,const char * group)58 gr_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 */
94 int
gr_lock(void)95 gr_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 */
124 int
gr_tmp(int mfd)125 gr_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 */
163 int
gr_copy(int ffd,int tfd,const struct group * gr,struct group * old_gr)164 gr_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 */
328 int
gr_mkdb(void)329 gr_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 */
358 void
gr_fini(void)359 gr_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 */
379 int
gr_equal(const struct group * gr1,const struct group * gr2)380 gr_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 */
425 char *
gr_make(const struct group * gr)426 gr_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 */
465 struct group *
gr_dup(const struct group * gr)466 gr_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 */
473 struct group *
gr_add(const struct group * gr,const char * newmember)474 gr_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 */
513 static struct group *
grcopy(const struct group * gr,char * dst,const char * name,int ndx)514 grcopy(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 */
560 static size_t
grmemlen(const struct group * gr,const char * name,int * num_mem)561 grmemlen(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 */
596 static bool
__gr_scan(char * line,struct group * gr)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 */
642 struct group *
gr_scan(const char * line)643 gr_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