1 /* $NetBSD: setmode.c,v 1.34 2012/06/25 22:32:43 abs Exp $ */
2
3 /*
4 * Copyright (c) 1989, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Dave Borman at Cray Research, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #include <sys/cdefs.h>
36 #if defined(LIBC_SCCS) && !defined(lint)
37 #if 0
38 static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94";
39 #else
40 __RCSID("$NetBSD: setmode.c,v 1.34 2012/06/25 22:32:43 abs Exp $");
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43
44 #include "namespace.h"
45 #include <sys/types.h>
46 #include <sys/stat.h>
47
48 #include <assert.h>
49 #include <ctype.h>
50 #include <errno.h>
51 #include <signal.h>
52 #include <stdlib.h>
53 #include <limits.h>
54 #include <unistd.h>
55
56 #ifdef SETMODE_DEBUG
57 #include <stdio.h>
58 #endif
59
60 #ifdef __weak_alias
61 __weak_alias(getmode,_getmode)
62 __weak_alias(setmode,_setmode)
63 #endif
64
65 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */
66 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */
67
68 typedef struct bitcmd {
69 char cmd;
70 char cmd2;
71 mode_t bits;
72 } BITCMD;
73
74 #define CMD2_CLR 0x01
75 #define CMD2_SET 0x02
76 #define CMD2_GBITS 0x04
77 #define CMD2_OBITS 0x08
78 #define CMD2_UBITS 0x10
79
80 static BITCMD *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t);
81 static void compress_mode(BITCMD *);
82 #ifdef SETMODE_DEBUG
83 static void dumpmode(BITCMD *);
84 #endif
85
86 /*
87 * Given the old mode and an array of bitcmd structures, apply the operations
88 * described in the bitcmd structures to the old mode, and return the new mode.
89 * Note that there is no '=' command; a strict assignment is just a '-' (clear
90 * bits) followed by a '+' (set bits).
91 */
92 mode_t
getmode(const void * bbox,mode_t omode)93 getmode(const void *bbox, mode_t omode)
94 {
95 const BITCMD *set;
96 mode_t clrval, newmode, value;
97
98 _DIAGASSERT(bbox != NULL);
99
100 set = (const BITCMD *)bbox;
101 newmode = omode;
102 for (value = 0;; set++)
103 switch(set->cmd) {
104 /*
105 * When copying the user, group or other bits around, we "know"
106 * where the bits are in the mode so that we can do shifts to
107 * copy them around. If we don't use shifts, it gets real
108 * grundgy with lots of single bit checks and bit sets.
109 */
110 case 'u':
111 value = (newmode & S_IRWXU) >> 6;
112 goto common;
113
114 case 'g':
115 value = (newmode & S_IRWXG) >> 3;
116 goto common;
117
118 case 'o':
119 value = newmode & S_IRWXO;
120 common: if (set->cmd2 & CMD2_CLR) {
121 clrval =
122 (set->cmd2 & CMD2_SET) ? S_IRWXO : value;
123 if (set->cmd2 & CMD2_UBITS)
124 newmode &= ~((clrval<<6) & set->bits);
125 if (set->cmd2 & CMD2_GBITS)
126 newmode &= ~((clrval<<3) & set->bits);
127 if (set->cmd2 & CMD2_OBITS)
128 newmode &= ~(clrval & set->bits);
129 }
130 if (set->cmd2 & CMD2_SET) {
131 if (set->cmd2 & CMD2_UBITS)
132 newmode |= (value<<6) & set->bits;
133 if (set->cmd2 & CMD2_GBITS)
134 newmode |= (value<<3) & set->bits;
135 if (set->cmd2 & CMD2_OBITS)
136 newmode |= value & set->bits;
137 }
138 break;
139
140 case '+':
141 newmode |= set->bits;
142 break;
143
144 case '-':
145 newmode &= ~set->bits;
146 break;
147
148 case 'X':
149 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
150 newmode |= set->bits;
151 break;
152
153 case '\0':
154 default:
155 #ifdef SETMODE_DEBUG
156 (void)printf("getmode:%04o -> %04o\n", omode, newmode);
157 #endif
158 return (newmode);
159 }
160 }
161
162 #define ADDCMD(a, b, c, d) do { \
163 if (set >= endset) { \
164 BITCMD *newset; \
165 setlen += SET_LEN_INCR; \
166 newset = realloc(saveset, sizeof(BITCMD) * setlen); \
167 if (newset == NULL) \
168 goto out; \
169 set = newset + (set - saveset); \
170 saveset = newset; \
171 endset = newset + (setlen - 2); \
172 } \
173 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d)); \
174 } while (/*CONSTCOND*/0)
175
176 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
177
178 void *
setmode(const char * p)179 setmode(const char *p)
180 {
181 int serrno;
182 char op, *ep;
183 BITCMD *set, *saveset, *endset;
184 sigset_t signset, sigoset;
185 mode_t mask, perm, permXbits, who;
186 long lval;
187 int equalopdone = 0; /* pacify gcc */
188 int setlen;
189
190 if (!*p) {
191 errno = EINVAL;
192 return NULL;
193 }
194
195 /*
196 * Get a copy of the mask for the permissions that are mask relative.
197 * Flip the bits, we want what's not set. Since it's possible that
198 * the caller is opening files inside a signal handler, protect them
199 * as best we can.
200 */
201 sigfillset(&signset);
202 (void)sigprocmask(SIG_BLOCK, &signset, &sigoset);
203 (void)umask(mask = umask(0));
204 mask = ~mask;
205 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
206
207 setlen = SET_LEN + 2;
208
209 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
210 return (NULL);
211 saveset = set;
212 endset = set + (setlen - 2);
213
214 /*
215 * If an absolute number, get it and return; disallow non-octal digits
216 * or illegal bits.
217 */
218 if (isdigit((unsigned char)*p)) {
219 errno = 0;
220 lval = strtol(p, &ep, 8);
221 if (*ep) {
222 errno = EINVAL;
223 goto out;
224 }
225 if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
226 goto out;
227 if (lval & ~(STANDARD_BITS|S_ISTXT)) {
228 errno = EINVAL;
229 goto out;
230 }
231 perm = (mode_t)lval;
232 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
233 set->cmd = 0;
234 return (saveset);
235 }
236
237 /*
238 * Build list of structures to set/clear/copy bits as described by
239 * each clause of the symbolic mode.
240 */
241 for (;;) {
242 /* First, find out which bits might be modified. */
243 for (who = 0;; ++p) {
244 switch (*p) {
245 case 'a':
246 who |= STANDARD_BITS;
247 break;
248 case 'u':
249 who |= S_ISUID|S_IRWXU;
250 break;
251 case 'g':
252 who |= S_ISGID|S_IRWXG;
253 break;
254 case 'o':
255 who |= S_IRWXO;
256 break;
257 default:
258 goto getop;
259 }
260 }
261
262 getop: if ((op = *p++) != '+' && op != '-' && op != '=') {
263 errno = EINVAL;
264 goto out;
265 }
266 if (op == '=')
267 equalopdone = 0;
268
269 who &= ~S_ISTXT;
270 for (perm = 0, permXbits = 0;; ++p) {
271 switch (*p) {
272 case 'r':
273 perm |= S_IRUSR|S_IRGRP|S_IROTH;
274 break;
275 case 's':
276 /*
277 * If specific bits where requested and
278 * only "other" bits ignore set-id.
279 */
280 if (who == 0 || (who & ~S_IRWXO))
281 perm |= S_ISUID|S_ISGID;
282 break;
283 case 't':
284 /*
285 * If specific bits where requested and
286 * only "other" bits ignore set-id.
287 */
288 if (who == 0 || (who & ~S_IRWXO)) {
289 who |= S_ISTXT;
290 perm |= S_ISTXT;
291 }
292 break;
293 case 'w':
294 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
295 break;
296 case 'X':
297 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
298 break;
299 case 'x':
300 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
301 break;
302 case 'u':
303 case 'g':
304 case 'o':
305 /*
306 * When ever we hit 'u', 'g', or 'o', we have
307 * to flush out any partial mode that we have,
308 * and then do the copying of the mode bits.
309 */
310 if (perm) {
311 ADDCMD(op, who, perm, mask);
312 perm = 0;
313 }
314 if (op == '=')
315 equalopdone = 1;
316 if (op == '+' && permXbits) {
317 ADDCMD('X', who, permXbits, mask);
318 permXbits = 0;
319 }
320 ADDCMD(*p, who, op, mask);
321 break;
322
323 default:
324 /*
325 * Add any permissions that we haven't already
326 * done.
327 */
328 if (perm || (op == '=' && !equalopdone)) {
329 if (op == '=')
330 equalopdone = 1;
331 ADDCMD(op, who, perm, mask);
332 perm = 0;
333 }
334 if (permXbits) {
335 ADDCMD('X', who, permXbits, mask);
336 permXbits = 0;
337 }
338 goto apply;
339 }
340 }
341
342 apply: if (!*p)
343 break;
344 if (*p != ',')
345 goto getop;
346 ++p;
347 }
348 set->cmd = 0;
349 #ifdef SETMODE_DEBUG
350 (void)printf("Before compress_mode()\n");
351 dumpmode(saveset);
352 #endif
353 compress_mode(saveset);
354 #ifdef SETMODE_DEBUG
355 (void)printf("After compress_mode()\n");
356 dumpmode(saveset);
357 #endif
358 return (saveset);
359 out:
360 serrno = errno;
361 free(saveset);
362 errno = serrno;
363 return NULL;
364 }
365
366 static BITCMD *
addcmd(BITCMD * set,mode_t op,mode_t who,mode_t oparg,mode_t mask)367 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
368 {
369
370 _DIAGASSERT(set != NULL);
371
372 switch (op) {
373 case '=':
374 set->cmd = '-';
375 set->bits = who ? who : STANDARD_BITS;
376 set++;
377
378 op = '+';
379 /* FALLTHROUGH */
380 case '+':
381 case '-':
382 case 'X':
383 set->cmd = op;
384 set->bits = (who ? who : mask) & oparg;
385 break;
386
387 case 'u':
388 case 'g':
389 case 'o':
390 set->cmd = op;
391 if (who) {
392 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
393 ((who & S_IRGRP) ? CMD2_GBITS : 0) |
394 ((who & S_IROTH) ? CMD2_OBITS : 0);
395 set->bits = (mode_t)~0;
396 } else {
397 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
398 set->bits = mask;
399 }
400
401 if (oparg == '+')
402 set->cmd2 |= CMD2_SET;
403 else if (oparg == '-')
404 set->cmd2 |= CMD2_CLR;
405 else if (oparg == '=')
406 set->cmd2 |= CMD2_SET|CMD2_CLR;
407 break;
408 }
409 return (set + 1);
410 }
411
412 #ifdef SETMODE_DEBUG
413 static void
dumpmode(BITCMD * set)414 dumpmode(BITCMD *set)
415 {
416
417 _DIAGASSERT(set != NULL);
418
419 for (; set->cmd; ++set)
420 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
421 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
422 set->cmd2 & CMD2_CLR ? " CLR" : "",
423 set->cmd2 & CMD2_SET ? " SET" : "",
424 set->cmd2 & CMD2_UBITS ? " UBITS" : "",
425 set->cmd2 & CMD2_GBITS ? " GBITS" : "",
426 set->cmd2 & CMD2_OBITS ? " OBITS" : "");
427 }
428 #endif
429
430 /*
431 * Given an array of bitcmd structures, compress by compacting consecutive
432 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u',
433 * 'g' and 'o' commands continue to be separate. They could probably be
434 * compacted, but it's not worth the effort.
435 */
436 static void
compress_mode(BITCMD * set)437 compress_mode(BITCMD *set)
438 {
439 BITCMD *nset;
440 int setbits, clrbits, Xbits, op;
441
442 _DIAGASSERT(set != NULL);
443
444 for (nset = set;;) {
445 /* Copy over any 'u', 'g' and 'o' commands. */
446 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
447 *set++ = *nset++;
448 if (!op)
449 return;
450 }
451
452 for (setbits = clrbits = Xbits = 0;; nset++) {
453 if ((op = nset->cmd) == '-') {
454 clrbits |= nset->bits;
455 setbits &= ~nset->bits;
456 Xbits &= ~nset->bits;
457 } else if (op == '+') {
458 setbits |= nset->bits;
459 clrbits &= ~nset->bits;
460 Xbits &= ~nset->bits;
461 } else if (op == 'X')
462 Xbits |= nset->bits & ~setbits;
463 else
464 break;
465 }
466 if (clrbits) {
467 set->cmd = '-';
468 set->cmd2 = 0;
469 set->bits = clrbits;
470 set++;
471 }
472 if (setbits) {
473 set->cmd = '+';
474 set->cmd2 = 0;
475 set->bits = setbits;
476 set++;
477 }
478 if (Xbits) {
479 set->cmd = 'X';
480 set->cmd2 = 0;
481 set->bits = Xbits;
482 set++;
483 }
484 }
485 }
486