source: MondoRescue/branches/3.3/mindi-busybox/libpwdgrp/pwd_grp.c@ 3621

Last change on this file since 3621 was 3621, checked in by Bruno Cornec, 7 years ago

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.
File size: 14.3 KB
Line 
1/* vi: set sw=4 ts=4: */
2/* Copyright (C) 2014 Tito Ragusa <farmatito@tiscali.it>
3 *
4 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
5 */
6/* This program is distributed in the hope that it will be useful,
7 * but WITHOUT ANY WARRANTY!!
8 *
9 * Rewrite of some parts. Main differences are:
10 *
11 * 1) the buffer for getpwuid, getgrgid, getpwnam, getgrnam is dynamically
12 * allocated.
13 * If ENABLE_FEATURE_CLEAN_UP is set the buffers are freed at program
14 * exit using the atexit function to make valgrind happy.
15 * 2) the passwd/group files:
16 * a) must contain the expected number of fields (as per count of field
17 * delimeters ":") or we will complain with a error message.
18 * b) leading and trailing whitespace in fields is stripped.
19 * c) some fields are not allowed to be empty (e.g. username, uid/gid),
20 * and in this case NULL is returned and errno is set to EINVAL.
21 * This behaviour could be easily changed by modifying PW_DEF, GR_DEF,
22 * SP_DEF strings (uppercase makes a field mandatory).
23 * d) the string representing uid/gid must be convertible by strtoXX
24 * functions, or errno is set to EINVAL.
25 * e) leading and trailing whitespace in group member names is stripped.
26 * 3) the internal function for getgrouplist uses dynamically allocated buffer.
27 * 4) at the moment only the functions really used by busybox code are
28 * implemented, if you need a particular missing function it should be
29 * easy to write it by using the internal common code.
30 */
31
32#include "libbb.h"
33
34struct const_passdb {
35 const char *filename;
36 char def[7 + 2*ENABLE_USE_BB_SHADOW];
37 uint8_t off[7 + 2*ENABLE_USE_BB_SHADOW];
38 uint8_t numfields;
39 uint8_t size_of;
40};
41struct passdb {
42 const char *filename;
43 char def[7 + 2*ENABLE_USE_BB_SHADOW];
44 uint8_t off[7 + 2*ENABLE_USE_BB_SHADOW];
45 uint8_t numfields;
46 uint8_t size_of;
47 FILE *fp;
48 char *malloced;
49};
50/* Note: for shadow db, def[] will not contain terminating NUL,
51 * but convert_to_struct() logic detects def[] end by "less than SP?",
52 * not by "is it NUL?" condition; and off[0] happens to be zero
53 * for every db anyway, so there _is_ in fact a terminating NUL there.
54 */
55
56/* S = string not empty, s = string maybe empty,
57 * I = uid,gid, l = long maybe empty, m = members,
58 * r = reserved
59 */
60#define PW_DEF "SsIIsss"
61#define GR_DEF "SsIm"
62#define SP_DEF "Ssllllllr"
63
64static const struct const_passdb const_pw_db = {
65 _PATH_PASSWD, PW_DEF,
66 {
67 offsetof(struct passwd, pw_name), /* 0 S */
68 offsetof(struct passwd, pw_passwd), /* 1 s */
69 offsetof(struct passwd, pw_uid), /* 2 I */
70 offsetof(struct passwd, pw_gid), /* 3 I */
71 offsetof(struct passwd, pw_gecos), /* 4 s */
72 offsetof(struct passwd, pw_dir), /* 5 s */
73 offsetof(struct passwd, pw_shell) /* 6 s */
74 },
75 sizeof(PW_DEF)-1, sizeof(struct passwd)
76};
77static const struct const_passdb const_gr_db = {
78 _PATH_GROUP, GR_DEF,
79 {
80 offsetof(struct group, gr_name), /* 0 S */
81 offsetof(struct group, gr_passwd), /* 1 s */
82 offsetof(struct group, gr_gid), /* 2 I */
83 offsetof(struct group, gr_mem) /* 3 m (char **) */
84 },
85 sizeof(GR_DEF)-1, sizeof(struct group)
86};
87#if ENABLE_USE_BB_SHADOW
88static const struct const_passdb const_sp_db = {
89 _PATH_SHADOW, SP_DEF,
90 {
91 offsetof(struct spwd, sp_namp), /* 0 S Login name */
92 offsetof(struct spwd, sp_pwdp), /* 1 s Encrypted password */
93 offsetof(struct spwd, sp_lstchg), /* 2 l */
94 offsetof(struct spwd, sp_min), /* 3 l */
95 offsetof(struct spwd, sp_max), /* 4 l */
96 offsetof(struct spwd, sp_warn), /* 5 l */
97 offsetof(struct spwd, sp_inact), /* 6 l */
98 offsetof(struct spwd, sp_expire), /* 7 l */
99 offsetof(struct spwd, sp_flag) /* 8 r Reserved */
100 },
101 sizeof(SP_DEF)-1, sizeof(struct spwd)
102};
103#endif
104
105/* We avoid having big global data. */
106struct statics {
107 /* We use same buffer (db[0].malloced) for getpwuid and getpwnam.
108 * Manpage says:
109 * "The return value may point to a static area, and may be overwritten
110 * by subsequent calls to getpwent(), getpwnam(), or getpwuid()."
111 */
112 struct passdb db[2 + ENABLE_USE_BB_SHADOW];
113 char *tokenize_end;
114 unsigned string_size;
115};
116
117static struct statics *ptr_to_statics;
118#define S (*ptr_to_statics)
119#define has_S (ptr_to_statics)
120
121#if ENABLE_FEATURE_CLEAN_UP
122static void free_static(void)
123{
124 free(S.db[0].malloced);
125 free(S.db[1].malloced);
126# if ENABLE_USE_BB_SHADOW
127 free(S.db[2].malloced);
128# endif
129 free(ptr_to_statics);
130}
131#endif
132
133static struct statics *get_S(void)
134{
135 if (!ptr_to_statics) {
136 ptr_to_statics = xzalloc(sizeof(S));
137 memcpy(&S.db[0], &const_pw_db, sizeof(const_pw_db));
138 memcpy(&S.db[1], &const_gr_db, sizeof(const_gr_db));
139#if ENABLE_USE_BB_SHADOW
140 memcpy(&S.db[2], &const_sp_db, sizeof(const_sp_db));
141#endif
142#if ENABLE_FEATURE_CLEAN_UP
143 atexit(free_static);
144#endif
145 }
146 return ptr_to_statics;
147}
148
149/* Internal functions */
150
151/* Divide the passwd/group/shadow record in fields
152 * by substituting the given delimeter
153 * e.g. ':' or ',' with '\0'.
154 * Returns the number of fields found.
155 * Strips leading and trailing whitespace in fields.
156 */
157static int tokenize(char *buffer, int ch)
158{
159 char *p = buffer;
160 char *s = p;
161 int num_fields = 0;
162
163 for (;;) {
164 if (isblank(*s)) {
165 overlapping_strcpy(s, skip_whitespace(s));
166 }
167 if (*p == ch || *p == '\0') {
168 char *end = p;
169 while (p != s && isblank(p[-1]))
170 p--;
171 if (p != end)
172 overlapping_strcpy(p, end);
173 num_fields++;
174 if (*end == '\0') {
175 S.tokenize_end = p + 1;
176 return num_fields;
177 }
178 *p = '\0';
179 s = p + 1;
180 }
181 p++;
182 }
183}
184
185/* Returns !NULL on success and matching line broken up in fields by '\0' in buf.
186 * We require the expected number of fields to be found.
187 */
188static char *parse_common(FILE *fp, struct passdb *db,
189 const char *key, int field_pos)
190{
191 char *buf;
192
193 while ((buf = xmalloc_fgetline(fp)) != NULL) {
194 /* Skip empty lines, comment lines */
195 if (buf[0] == '\0' || buf[0] == '#')
196 goto free_and_next;
197 if (tokenize(buf, ':') != db->numfields) {
198 /* number of fields is wrong */
199 bb_error_msg("%s: bad record", db->filename);
200 goto free_and_next;
201 }
202
203 if (field_pos == -1) {
204 /* no key specified: sequential read, return a record */
205 break;
206 }
207 if (strcmp(key, nth_string(buf, field_pos)) == 0) {
208 /* record found */
209 break;
210 }
211 free_and_next:
212 free(buf);
213 }
214
215 S.string_size = S.tokenize_end - buf;
216/*
217 * Ugly hack: group db requires additional buffer space
218 * for members[] array. If there is only one group, we need space
219 * for 3 pointers: alignment padding, group name, NULL.
220 * +1 for every additional group.
221 */
222 if (buf && db->numfields == sizeof(GR_DEF)-1) { /* if we read group file... */
223 int cnt = 3;
224 char *p = buf;
225 while (p < S.tokenize_end)
226 if (*p++ == ',')
227 cnt++;
228 S.string_size += cnt * sizeof(char*);
229//bb_error_msg("+%d words = %u key:%s buf:'%s'", cnt, S.string_size, key, buf);
230 buf = xrealloc(buf, S.string_size);
231 }
232
233 return buf;
234}
235
236static char *parse_file(struct passdb *db,
237 const char *key, int field_pos)
238{
239 char *buf = NULL;
240 FILE *fp = fopen_for_read(db->filename);
241
242 if (fp) {
243 buf = parse_common(fp, db, key, field_pos);
244 fclose(fp);
245 }
246 return buf;
247}
248
249/* Convert passwd/group/shadow file record in buffer to a struct */
250static void *convert_to_struct(struct passdb *db,
251 char *buffer, void *result)
252{
253 const char *def = db->def;
254 const uint8_t *off = db->off;
255
256 /* For consistency, zero out all fields */
257 memset(result, 0, db->size_of);
258
259 for (;;) {
260 void *member = (char*)result + (*off++);
261
262 if ((*def | 0x20) == 's') { /* s or S */
263 *(char **)member = (char*)buffer;
264 if (!buffer[0] && (*def == 'S')) {
265 errno = EINVAL;
266 }
267 }
268 if (*def == 'I') {
269 *(int *)member = bb_strtou(buffer, NULL, 10);
270 }
271#if ENABLE_USE_BB_SHADOW
272 if (*def == 'l') {
273 long n = -1;
274 if (buffer[0])
275 n = bb_strtol(buffer, NULL, 10);
276 *(long *)member = n;
277 }
278#endif
279 if (*def == 'm') {
280 char **members;
281 int i = tokenize(buffer, ',');
282
283 /* Store members[] after buffer's end.
284 * This is safe ONLY because there is a hack
285 * in parse_common() which allocates additional space
286 * at the end of malloced buffer!
287 */
288 members = (char **)
289 ( ((intptr_t)S.tokenize_end + sizeof(members[0]))
290 & -(intptr_t)sizeof(members[0])
291 );
292 ((struct group *)result)->gr_mem = members;
293 while (--i >= 0) {
294 if (buffer[0]) {
295 *members++ = buffer;
296 // bb_error_msg("member[]='%s'", buffer);
297 }
298 buffer += strlen(buffer) + 1;
299 }
300 *members = NULL;
301 }
302 /* def "r" does nothing */
303
304 def++;
305 if ((unsigned char)*def <= (unsigned char)' ')
306 break;
307 buffer += strlen(buffer) + 1;
308 }
309
310 if (errno)
311 result = NULL;
312 return result;
313}
314
315static int massage_data_for_r_func(struct passdb *db,
316 char *buffer, size_t buflen,
317 void **result,
318 char *buf)
319{
320 void *result_buf = *result;
321 *result = NULL;
322 if (buf) {
323 if (S.string_size > buflen) {
324 errno = ERANGE;
325 } else {
326 memcpy(buffer, buf, S.string_size);
327 *result = convert_to_struct(db, buffer, result_buf);
328 }
329 free(buf);
330 }
331 /* "The reentrant functions return zero on success.
332 * In case of error, an error number is returned."
333 * NB: not finding the record is also a "success" here:
334 */
335 return errno;
336}
337
338static void* massage_data_for_non_r_func(struct passdb *db, char *buf)
339{
340 if (!buf)
341 return NULL;
342
343 free(db->malloced);
344 /* We enlarge buf and move string data up, freeing space
345 * for struct passwd/group/spwd at the beginning. This way,
346 * entire result of getXXnam is in a single malloced block.
347 * This enables easy creation of xmalloc_getpwnam() API.
348 */
349 db->malloced = buf = xrealloc(buf, db->size_of + S.string_size);
350 memmove(buf + db->size_of, buf, S.string_size);
351 return convert_to_struct(db, buf + db->size_of, buf);
352}
353
354/****** getXXnam/id_r */
355
356static int FAST_FUNC getXXnam_r(const char *name, uintptr_t db_and_field_pos,
357 char *buffer, size_t buflen,
358 void *result)
359{
360 char *buf;
361 struct passdb *db = &get_S()->db[db_and_field_pos >> 2];
362
363 buf = parse_file(db, name, 0 /*db_and_field_pos & 3*/);
364 /* "db_and_field_pos & 3" is commented out since so far we don't implement
365 * getXXXid_r() functions which would use that to pass 2 here */
366
367 return massage_data_for_r_func(db, buffer, buflen, result, buf);
368}
369
370int FAST_FUNC getpwnam_r(const char *name, struct passwd *struct_buf,
371 char *buffer, size_t buflen,
372 struct passwd **result)
373{
374 /* Why the "store buffer address in result" trick?
375 * This way, getXXnam_r has the same ABI signature as getpwnam_r,
376 * hopefully compiler can optimize tail call better in this case.
377 */
378 *result = struct_buf;
379 return getXXnam_r(name, (0 << 2) + 0, buffer, buflen, result);
380}
381#if ENABLE_USE_BB_SHADOW
382int FAST_FUNC getspnam_r(const char *name, struct spwd *struct_buf, char *buffer, size_t buflen,
383 struct spwd **result)
384{
385 *result = struct_buf;
386 return getXXnam_r(name, (2 << 2) + 0, buffer, buflen, result);
387}
388#endif
389
390#ifdef UNUSED
391/****** getXXent_r */
392
393static int FAST_FUNC getXXent_r(uintptr_t db_idx, char *buffer, size_t buflen,
394 void *result)
395{
396 char *buf;
397 struct passdb *db = &get_S()->db[db_idx];
398
399 if (!db->fp) {
400 db->fp = fopen_for_read(db->filename);
401 if (!db->fp) {
402 return errno;
403 }
404 close_on_exec_on(fileno(db->fp));
405 }
406
407 buf = parse_common(db->fp, db, /*no search key:*/ NULL, -1);
408 if (!buf && !errno)
409 errno = ENOENT;
410 return massage_data_for_r_func(db, buffer, buflen, result, buf);
411}
412
413int FAST_FUNC getpwent_r(struct passwd *struct_buf, char *buffer, size_t buflen,
414 struct passwd **result)
415{
416 *result = struct_buf;
417 return getXXent_r(0, buffer, buflen, result);
418}
419#endif
420
421/****** getXXent */
422
423static void* FAST_FUNC getXXent(uintptr_t db_idx)
424{
425 char *buf;
426 struct passdb *db = &get_S()->db[db_idx];
427
428 if (!db->fp) {
429 db->fp = fopen_for_read(db->filename);
430 if (!db->fp) {
431 return NULL;
432 }
433 close_on_exec_on(fileno(db->fp));
434 }
435
436 buf = parse_common(db->fp, db, /*no search key:*/ NULL, -1);
437 return massage_data_for_non_r_func(db, buf);
438}
439
440struct passwd* FAST_FUNC getpwent(void)
441{
442 return getXXent(0);
443}
444
445/****** getXXnam/id */
446
447static void* FAST_FUNC getXXnam(const char *name, unsigned db_and_field_pos)
448{
449 char *buf;
450 struct passdb *db = &get_S()->db[db_and_field_pos >> 2];
451
452 buf = parse_file(db, name, db_and_field_pos & 3);
453 return massage_data_for_non_r_func(db, buf);
454}
455
456struct passwd* FAST_FUNC getpwnam(const char *name)
457{
458 return getXXnam(name, (0 << 2) + 0);
459}
460struct group* FAST_FUNC getgrnam(const char *name)
461{
462 return getXXnam(name, (1 << 2) + 0);
463}
464struct passwd* FAST_FUNC getpwuid(uid_t id)
465{
466 return getXXnam(utoa(id), (0 << 2) + 2);
467}
468struct group* FAST_FUNC getgrgid(gid_t id)
469{
470 return getXXnam(utoa(id), (1 << 2) + 2);
471}
472
473/****** end/setXXend */
474
475void FAST_FUNC endpwent(void)
476{
477 if (has_S && S.db[0].fp) {
478 fclose(S.db[0].fp);
479 S.db[0].fp = NULL;
480 }
481}
482void FAST_FUNC setpwent(void)
483{
484 if (has_S && S.db[0].fp) {
485 rewind(S.db[0].fp);
486 }
487}
488void FAST_FUNC endgrent(void)
489{
490 if (has_S && S.db[1].fp) {
491 fclose(S.db[1].fp);
492 S.db[1].fp = NULL;
493 }
494}
495
496/****** initgroups and getgrouplist */
497
498static gid_t* FAST_FUNC getgrouplist_internal(int *ngroups_ptr,
499 const char *user, gid_t gid)
500{
501 FILE *fp;
502 gid_t *group_list;
503 int ngroups;
504
505 /* We alloc space for 8 gids at a time. */
506 group_list = xzalloc(8 * sizeof(group_list[0]));
507 group_list[0] = gid;
508 ngroups = 1;
509
510 fp = fopen_for_read(_PATH_GROUP);
511 if (fp) {
512 struct passdb *db = &get_S()->db[1];
513 char *buf;
514 while ((buf = parse_common(fp, db, NULL, -1)) != NULL) {
515 char **m;
516 struct group group;
517 if (!convert_to_struct(db, buf, &group))
518 goto next;
519 if (group.gr_gid == gid)
520 goto next;
521 for (m = group.gr_mem; *m; m++) {
522 if (strcmp(*m, user) != 0)
523 continue;
524 group_list = xrealloc_vector(group_list, /*8=2^3:*/ 3, ngroups);
525 group_list[ngroups++] = group.gr_gid;
526 goto next;
527 }
528 next:
529 free(buf);
530 }
531 fclose(fp);
532 }
533 *ngroups_ptr = ngroups;
534 return group_list;
535}
536
537int FAST_FUNC initgroups(const char *user, gid_t gid)
538{
539 int ngroups;
540 gid_t *group_list = getgrouplist_internal(&ngroups, user, gid);
541
542 ngroups = setgroups(ngroups, group_list);
543 free(group_list);
544 return ngroups;
545}
546
547int FAST_FUNC getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
548{
549 int ngroups_old = *ngroups;
550 gid_t *group_list = getgrouplist_internal(ngroups, user, gid);
551
552 if (*ngroups <= ngroups_old) {
553 ngroups_old = *ngroups;
554 memcpy(groups, group_list, ngroups_old * sizeof(groups[0]));
555 } else {
556 ngroups_old = -1;
557 }
558 free(group_list);
559 return ngroups_old;
560}
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