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 * $FreeBSD: head/lib/libutil/gr_util.c 248102 2013-03-09 13:30:06Z db $
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 = mkstemp(tempname)) == -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[8192], *end, *line, *p, *q, *r, t;
167 struct group *fgr;
168 const struct group *sgr;
169 size_t len;
170 int eof, readlen;
171
172 sgr = gr;
173 if (gr == NULL) {
174 line = NULL;
175 if (old_gr == NULL)
176 return (-1);
177 sgr = old_gr;
178 } else if ((line = gr_make(gr)) == NULL)
179 return (-1);
180
181 eof = 0;
182 len = 0;
183 p = q = end = buf;
184 for (;;) {
185 /* find the end of the current line */
186 for (p = q; q < end && *q != '\0'; ++q)
187 if (*q == '\n')
188 break;
189
190 /* if we don't have a complete line, fill up the buffer */
191 if (q >= end) {
192 if (eof)
193 break;
194 if ((size_t)(q - p) >= sizeof(buf)) {
195 warnx("group line too long");
196 errno = EINVAL; /* hack */
197 goto err;
198 }
199 if (p < end) {
200 q = memmove(buf, p, end -p);
201 end -= p - buf;
202 } else {
203 p = q = end = buf;
204 }
205 readlen = read(ffd, end, sizeof(buf) - (end -buf));
206 if (readlen == -1)
207 goto err;
208 else
209 len = (size_t)readlen;
210 if (len == 0 && p == buf)
211 break;
212 end += len;
213 len = end - buf;
214 if (len < (ssize_t)sizeof(buf)) {
215 eof = 1;
216 if (len > 0 && buf[len -1] != '\n')
217 ++len, *end++ = '\n';
218 }
219 continue;
220 }
221
222 /* is it a blank line or a comment? */
223 for (r = p; r < q && isspace(*r); ++r)
224 /* nothing */;
225 if (r == q || *r == '#') {
226 /* yep */
227 if (write(tfd, p, q -p + 1) != q - p + 1)
228 goto err;
229 ++q;
230 continue;
231 }
232
233 /* is it the one we're looking for? */
234
235 t = *q;
236 *q = '\0';
237
238 fgr = gr_scan(r);
239
240 /* fgr is either a struct group for the current line,
241 * or NULL if the line is malformed.
242 */
243
244 *q = t;
245 if (fgr == NULL || fgr->gr_gid != sgr->gr_gid) {
246 /* nope */
247 if (fgr != NULL)
248 free(fgr);
249 if (write(tfd, p, q - p + 1) != q - p + 1)
250 goto err;
251 ++q;
252 continue;
253 }
254 if (old_gr && !gr_equal(fgr, old_gr)) {
255 warnx("entry inconsistent");
256 free(fgr);
257 errno = EINVAL; /* hack */
258 goto err;
259 }
260 free(fgr);
261
262 /* it is, replace or remove it */
263 if (line != NULL) {
264 len = strlen(line);
265 if (write(tfd, line, len) != (int) len)
266 goto err;
267 } else {
268 /* when removed, avoid the \n */
269 q++;
270 }
271 /* we're done, just copy the rest over */
272 for (;;) {
273 if (write(tfd, q, end - q) != end - q)
274 goto err;
275 q = buf;
276 readlen = read(ffd, buf, sizeof(buf));
277 if (readlen == 0)
278 break;
279 else
280 len = (size_t)readlen;
281 if (readlen == -1)
282 goto err;
283 end = buf + len;
284 }
285 goto done;
286 }
287
288 /* if we got here, we didn't find the old entry */
289 if (line == NULL) {
290 errno = ENOENT;
291 goto err;
292 }
293 len = strlen(line);
294 if ((size_t)write(tfd, line, len) != len ||
295 write(tfd, "\n", 1) != 1)
296 goto err;
297 done:
298 if (line != NULL)
299 free(line);
300 return (0);
301 err:
302 if (line != NULL)
303 free(line);
304 return (-1);
305 }
306
307 /*
308 * Regenerate the group file
309 */
310 int
gr_mkdb(void)311 gr_mkdb(void)
312 {
313 if (chmod(tempname, 0644) != 0)
314 return (-1);
315
316 return (rename(tempname, group_file));
317 }
318
319 /*
320 * Clean up. Preserves errno for the caller's convenience.
321 */
322 void
gr_fini(void)323 gr_fini(void)
324 {
325 int serrno;
326
327 if (!initialized)
328 return;
329 initialized = 0;
330 serrno = errno;
331 if (*tempname != '\0') {
332 unlink(tempname);
333 *tempname = '\0';
334 }
335 if (lockfd != -1)
336 close(lockfd);
337 errno = serrno;
338 }
339
340 /*
341 * Compares two struct group's.
342 */
343 int
gr_equal(const struct group * gr1,const struct group * gr2)344 gr_equal(const struct group *gr1, const struct group *gr2)
345 {
346 int gr1_ndx;
347 int gr2_ndx;
348
349 /* Check that the non-member information is the same. */
350 if (gr1->gr_name == NULL || gr2->gr_name == NULL) {
351 if (gr1->gr_name != gr2->gr_name)
352 return (false);
353 } else if (strcmp(gr1->gr_name, gr2->gr_name) != 0)
354 return (false);
355 if (gr1->gr_passwd == NULL || gr2->gr_passwd == NULL) {
356 if (gr1->gr_passwd != gr2->gr_passwd)
357 return (false);
358 } else if (strcmp(gr1->gr_passwd, gr2->gr_passwd) != 0)
359 return (false);
360 if (gr1->gr_gid != gr2->gr_gid)
361 return (false);
362
363 /* Check all members in both groups.
364 * getgrnam can return gr_mem with a pointer to NULL.
365 * gr_dup and gr_add strip out this superfluous NULL, setting
366 * gr_mem to NULL for no members.
367 */
368 if (gr1->gr_mem != NULL && gr2->gr_mem != NULL) {
369 int i;
370
371 for (i = 0; gr1->gr_mem[i] != NULL; i++) {
372 if (strcmp(gr1->gr_mem[i], gr2->gr_mem[i]) != 0)
373 return (false);
374 }
375 }
376 /* Count number of members in both structs */
377 gr2_ndx = 0;
378 if (gr2->gr_mem != NULL)
379 for(; gr2->gr_mem[gr2_ndx] != NULL; gr2_ndx++)
380 /* empty */;
381 gr1_ndx = 0;
382 if (gr1->gr_mem != NULL)
383 for(; gr1->gr_mem[gr1_ndx] != NULL; gr1_ndx++)
384 /* empty */;
385 if (gr1_ndx != gr2_ndx)
386 return (false);
387
388 return (true);
389 }
390
391 /*
392 * Make a group line out of a struct group.
393 */
394 char *
gr_make(const struct group * gr)395 gr_make(const struct group *gr)
396 {
397 const char *group_line_format = "%s:%s:%ju:";
398 const char *sep;
399 char *line;
400 char *p;
401 size_t line_size;
402 int ndx;
403
404 /* Calculate the length of the group line. */
405 line_size = snprintf(NULL, 0, group_line_format, gr->gr_name,
406 gr->gr_passwd, (uintmax_t)gr->gr_gid) + 1;
407 if (gr->gr_mem != NULL) {
408 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++)
409 line_size += strlen(gr->gr_mem[ndx]) + 1;
410 if (ndx > 0)
411 line_size--;
412 }
413
414 /* Create the group line and fill it. */
415 if ((line = p = malloc(line_size)) == NULL)
416 return (NULL);
417 p += sprintf(p, group_line_format, gr->gr_name, gr->gr_passwd,
418 (uintmax_t)gr->gr_gid);
419 if (gr->gr_mem != NULL) {
420 sep = "";
421 for (ndx = 0; gr->gr_mem[ndx] != NULL; ndx++) {
422 p = stpcpy(p, sep);
423 p = stpcpy(p, gr->gr_mem[ndx]);
424 sep = ",";
425 }
426 }
427
428 return (line);
429 }
430
431 /*
432 * Duplicate a struct group.
433 */
434 struct group *
gr_dup(const struct group * gr)435 gr_dup(const struct group *gr)
436 {
437 return (gr_add(gr, NULL));
438 }
439 /*
440 * Add a new member name to a struct group.
441 */
442 struct group *
gr_add(const struct group * gr,const char * newmember)443 gr_add(const struct group *gr, const char *newmember)
444 {
445 char *mem;
446 size_t len;
447 int num_mem;
448
449 num_mem = 0;
450 len = grmemlen(gr, newmember, &num_mem);
451 /* Create new group and copy old group into it. */
452 if ((mem = malloc(len)) == NULL)
453 return (NULL);
454 return (grcopy(gr, mem, newmember, num_mem));
455 }
456
457 /* It is safer to walk the pointers given at gr_mem since there is no
458 * guarantee the gr_mem + strings are contiguous in the given struct group
459 * but compactify the new group into the following form.
460 *
461 * The new struct is laid out like this in memory. The example given is
462 * for a group with two members only.
463 *
464 * {
465 * (char *name)
466 * (char *passwd)
467 * (int gid)
468 * (gr_mem * newgrp + sizeof(struct group) + sizeof(**)) points to gr_mem area
469 * gr_mem area
470 * (member1 *)
471 * (member2 *)
472 * (NULL)
473 * (name string)
474 * (passwd string)
475 * (member1 string)
476 * (member2 string)
477 * }
478 */
479 /*
480 * Copy the contents of a group plus given name to a preallocated group struct
481 */
482 static struct group *
grcopy(const struct group * gr,char * dst,const char * name,int ndx)483 grcopy(const struct group *gr, char *dst, const char *name, int ndx)
484 {
485 int i;
486 struct group *newgr;
487
488 newgr = (struct group *)(void *)dst; /* avoid alignment warning */
489 dst += sizeof(*newgr);
490 if (ndx != 0) {
491 newgr->gr_mem = (char **)(void *)(dst); /* avoid alignment warning */
492 dst += (ndx + 1) * sizeof(*newgr->gr_mem);
493 } else
494 newgr->gr_mem = NULL;
495 if (gr->gr_name != NULL) {
496 newgr->gr_name = dst;
497 dst = stpcpy(dst, gr->gr_name) + 1;
498 } else
499 newgr->gr_name = NULL;
500 if (gr->gr_passwd != NULL) {
501 newgr->gr_passwd = dst;
502 dst = stpcpy(dst, gr->gr_passwd) + 1;
503 } else
504 newgr->gr_passwd = NULL;
505 newgr->gr_gid = gr->gr_gid;
506 i = 0;
507 /* Original group struct might have a NULL gr_mem */
508 if (gr->gr_mem != NULL) {
509 for (; gr->gr_mem[i] != NULL; i++) {
510 newgr->gr_mem[i] = dst;
511 dst = stpcpy(dst, gr->gr_mem[i]) + 1;
512 }
513 }
514 /* If name is not NULL, newgr->gr_mem is known to be not NULL */
515 if (name != NULL) {
516 newgr->gr_mem[i++] = dst;
517 dst = stpcpy(dst, name) + 1;
518 }
519 /* if newgr->gr_mem is not NULL add NULL marker */
520 if (newgr->gr_mem != NULL)
521 newgr->gr_mem[i] = NULL;
522
523 return (newgr);
524 }
525
526 /*
527 * Calculate length of a struct group + given name
528 */
529 static size_t
grmemlen(const struct group * gr,const char * name,int * num_mem)530 grmemlen(const struct group *gr, const char *name, int *num_mem)
531 {
532 size_t len;
533 int i;
534
535 if (gr == NULL)
536 return (0);
537 /* Calculate size of the group. */
538 len = sizeof(*gr);
539 if (gr->gr_name != NULL)
540 len += strlen(gr->gr_name) + 1;
541 if (gr->gr_passwd != NULL)
542 len += strlen(gr->gr_passwd) + 1;
543 i = 0;
544 if (gr->gr_mem != NULL) {
545 for (; gr->gr_mem[i] != NULL; i++) {
546 len += strlen(gr->gr_mem[i]) + 1;
547 len += sizeof(*gr->gr_mem);
548 }
549 }
550 if (name != NULL) {
551 i++;
552 len += strlen(name) + 1;
553 len += sizeof(*gr->gr_mem);
554 }
555 /* Allow for NULL pointer */
556 if (i != 0)
557 len += sizeof(*gr->gr_mem);
558 *num_mem = i;
559 return(len);
560 }
561
562 /*
563 * Scan a line and place it into a group structure.
564 */
565 static bool
__gr_scan(char * line,struct group * gr)566 __gr_scan(char *line, struct group *gr)
567 {
568 char *loc;
569 int ndx;
570
571 /* Assign non-member information to structure. */
572 gr->gr_name = line;
573 if ((loc = strchr(line, ':')) == NULL)
574 return (false);
575 *loc = '\0';
576 gr->gr_passwd = loc + 1;
577 if (*gr->gr_passwd == ':')
578 *gr->gr_passwd = '\0';
579 else {
580 if ((loc = strchr(loc + 1, ':')) == NULL)
581 return (false);
582 *loc = '\0';
583 }
584 if (sscanf(loc + 1, "%u", &gr->gr_gid) != 1)
585 return (false);
586
587 /* Assign member information to structure. */
588 if ((loc = strchr(loc + 1, ':')) == NULL)
589 return (false);
590 line = loc + 1;
591 gr->gr_mem = NULL;
592 ndx = 0;
593 do {
594 gr->gr_mem = reallocf(gr->gr_mem, sizeof(*gr->gr_mem) *
595 (ndx + 1));
596 if (gr->gr_mem == NULL)
597 return (false);
598
599 /* Skip locations without members (i.e., empty string). */
600 do {
601 gr->gr_mem[ndx] = strsep(&line, ",");
602 } while (gr->gr_mem[ndx] != NULL && *gr->gr_mem[ndx] == '\0');
603 } while (gr->gr_mem[ndx++] != NULL);
604
605 return (true);
606 }
607
608 /*
609 * Create a struct group from a line.
610 */
611 struct group *
gr_scan(const char * line)612 gr_scan(const char *line)
613 {
614 struct group gr;
615 char *line_copy;
616 struct group *new_gr;
617
618 if ((line_copy = strdup(line)) == NULL)
619 return (NULL);
620 if (!__gr_scan(line_copy, &gr)) {
621 free(line_copy);
622 return (NULL);
623 }
624 new_gr = gr_dup(&gr);
625 free(line_copy);
626 if (gr.gr_mem != NULL)
627 free(gr.gr_mem);
628
629 return (new_gr);
630 }
631