1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 __SCCSID("@(#)setmode.c 8.2 (Berkeley) 3/25/94");
37 #include "namespace.h"
38 #include <sys/types.h>
39 #include <sys/stat.h>
40 #include <sys/sysctl.h>
41
42 #include <ctype.h>
43 #include <errno.h>
44 #include <limits.h>
45 #include <signal.h>
46 #include <stddef.h>
47 #include <stdlib.h>
48 #include <unistd.h>
49
50 #ifdef SETMODE_DEBUG
51 #include <stdio.h>
52 #endif
53 #include "un-namespace.h"
54 #include "libc_private.h"
55
56 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */
57 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */
58
59 typedef struct bitcmd {
60 char cmd;
61 char cmd2;
62 mode_t bits;
63 } BITCMD;
64
65 #define CMD2_CLR 0x01
66 #define CMD2_SET 0x02
67 #define CMD2_GBITS 0x04
68 #define CMD2_OBITS 0x08
69 #define CMD2_UBITS 0x10
70
71 static mode_t get_current_umask(void);
72 static BITCMD *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t);
73 static void compress_mode(BITCMD *);
74 #ifdef SETMODE_DEBUG
75 static void dumpmode(BITCMD *);
76 #endif
77
78 /*
79 * Given the old mode and an array of bitcmd structures, apply the operations
80 * described in the bitcmd structures to the old mode, and return the new mode.
81 * Note that there is no '=' command; a strict assignment is just a '-' (clear
82 * bits) followed by a '+' (set bits).
83 */
84 mode_t
getmode(const void * bbox,mode_t omode)85 getmode(const void *bbox, mode_t omode)
86 {
87 const BITCMD *set;
88 mode_t clrval, newmode, value;
89
90 set = (const BITCMD *)bbox;
91 newmode = omode;
92 for (value = 0;; set++)
93 switch(set->cmd) {
94 /*
95 * When copying the user, group or other bits around, we "know"
96 * where the bits are in the mode so that we can do shifts to
97 * copy them around. If we don't use shifts, it gets real
98 * grundgy with lots of single bit checks and bit sets.
99 */
100 case 'u':
101 value = (newmode & S_IRWXU) >> 6;
102 goto common;
103
104 case 'g':
105 value = (newmode & S_IRWXG) >> 3;
106 goto common;
107
108 case 'o':
109 value = newmode & S_IRWXO;
110 common: if (set->cmd2 & CMD2_CLR) {
111 clrval =
112 (set->cmd2 & CMD2_SET) ? S_IRWXO : value;
113 if (set->cmd2 & CMD2_UBITS)
114 newmode &= ~((clrval<<6) & set->bits);
115 if (set->cmd2 & CMD2_GBITS)
116 newmode &= ~((clrval<<3) & set->bits);
117 if (set->cmd2 & CMD2_OBITS)
118 newmode &= ~(clrval & set->bits);
119 }
120 if (set->cmd2 & CMD2_SET) {
121 if (set->cmd2 & CMD2_UBITS)
122 newmode |= (value<<6) & set->bits;
123 if (set->cmd2 & CMD2_GBITS)
124 newmode |= (value<<3) & set->bits;
125 if (set->cmd2 & CMD2_OBITS)
126 newmode |= value & set->bits;
127 }
128 break;
129
130 case '+':
131 newmode |= set->bits;
132 break;
133
134 case '-':
135 newmode &= ~set->bits;
136 break;
137
138 case 'X':
139 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
140 newmode |= set->bits;
141 break;
142
143 case '\0':
144 default:
145 #ifdef SETMODE_DEBUG
146 (void)printf("getmode:%04o -> %04o\n", omode, newmode);
147 #endif
148 return (newmode);
149 }
150 }
151
152 #define ADDCMD(a, b, c, d) \
153 if (set >= endset) { \
154 BITCMD *newset; \
155 setlen += SET_LEN_INCR; \
156 newset = reallocarray(saveset, setlen, sizeof(BITCMD)); \
157 if (newset == NULL) \
158 goto out; \
159 set = newset + (set - saveset); \
160 saveset = newset; \
161 endset = newset + (setlen - 2); \
162 } \
163 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d))
164
165 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
166
167 void *
setmode(const char * p)168 setmode(const char *p)
169 {
170 int serrno;
171 char op, *ep;
172 BITCMD *set, *saveset, *endset;
173 mode_t mask, perm, permXbits, who;
174 long perml;
175 int equalopdone;
176 u_int setlen;
177
178 if (!*p) {
179 errno = EINVAL;
180 return (NULL);
181 }
182
183 /*
184 * Get a copy of the mask for the permissions that are mask relative.
185 * Flip the bits, we want what's not set.
186 */
187 mask = ~get_current_umask();
188
189 setlen = SET_LEN + 2;
190
191 if ((set = malloc(setlen * sizeof(BITCMD))) == NULL)
192 return (NULL);
193 saveset = set;
194 endset = set + (setlen - 2);
195
196 /*
197 * If an absolute number, get it and return; disallow non-octal digits
198 * or illegal bits.
199 */
200 if (isdigit((unsigned char)*p)) {
201 errno = 0;
202 perml = strtol(p, &ep, 8);
203 if (*ep) {
204 errno = EINVAL;
205 goto out;
206 }
207 if (errno == ERANGE && (perml == LONG_MAX || perml == LONG_MIN))
208 goto out;
209 if (perml & ~(STANDARD_BITS|S_ISTXT)) {
210 errno = EINVAL;
211 goto out;
212 }
213 perm = (mode_t)perml;
214 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
215 set->cmd = 0;
216 return (saveset);
217 }
218
219 /*
220 * Build list of structures to set/clear/copy bits as described by
221 * each clause of the symbolic mode.
222 */
223 equalopdone = 0;
224 for (;;) {
225 /* First, find out which bits might be modified. */
226 for (who = 0;; ++p) {
227 switch (*p) {
228 case 'a':
229 who |= STANDARD_BITS;
230 break;
231 case 'u':
232 who |= S_ISUID|S_IRWXU;
233 break;
234 case 'g':
235 who |= S_ISGID|S_IRWXG;
236 break;
237 case 'o':
238 who |= S_IRWXO;
239 break;
240 default:
241 goto getop;
242 }
243 }
244
245 getop: if ((op = *p++) != '+' && op != '-' && op != '=') {
246 errno = EINVAL;
247 goto out;
248 }
249 if (op == '=')
250 equalopdone = 0;
251
252 who &= ~S_ISTXT;
253 for (perm = 0, permXbits = 0;; ++p) {
254 switch (*p) {
255 case 'r':
256 perm |= S_IRUSR|S_IRGRP|S_IROTH;
257 break;
258 case 's':
259 /* If only "other" bits ignore set-id. */
260 if (!who || who & ~S_IRWXO)
261 perm |= S_ISUID|S_ISGID;
262 break;
263 case 't':
264 /* If only "other" bits ignore sticky. */
265 if (!who || who & ~S_IRWXO) {
266 who |= S_ISTXT;
267 perm |= S_ISTXT;
268 }
269 break;
270 case 'w':
271 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
272 break;
273 case 'X':
274 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
275 break;
276 case 'x':
277 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
278 break;
279 case 'u':
280 case 'g':
281 case 'o':
282 /*
283 * When ever we hit 'u', 'g', or 'o', we have
284 * to flush out any partial mode that we have,
285 * and then do the copying of the mode bits.
286 */
287 if (perm) {
288 ADDCMD(op, who, perm, mask);
289 perm = 0;
290 }
291 if (op == '=')
292 equalopdone = 1;
293 if (op == '+' && permXbits) {
294 ADDCMD('X', who, permXbits, mask);
295 permXbits = 0;
296 }
297 ADDCMD(*p, who, op, mask);
298 break;
299
300 default:
301 /*
302 * Add any permissions that we haven't already
303 * done.
304 */
305 if (perm || (op == '=' && !equalopdone)) {
306 if (op == '=')
307 equalopdone = 1;
308 ADDCMD(op, who, perm, mask);
309 perm = 0;
310 }
311 if (permXbits) {
312 ADDCMD('X', who, permXbits, mask);
313 permXbits = 0;
314 }
315 goto apply;
316 }
317 }
318
319 apply: if (!*p)
320 break;
321 if (*p != ',')
322 goto getop;
323 ++p;
324 }
325 set->cmd = 0;
326 #ifdef SETMODE_DEBUG
327 (void)printf("Before compress_mode()\n");
328 dumpmode(saveset);
329 #endif
330 compress_mode(saveset);
331 #ifdef SETMODE_DEBUG
332 (void)printf("After compress_mode()\n");
333 dumpmode(saveset);
334 #endif
335 return (saveset);
336 out:
337 serrno = errno;
338 free(saveset);
339 errno = serrno;
340 return NULL;
341 }
342
343 static mode_t
get_current_umask(void)344 get_current_umask(void)
345 {
346 sigset_t sigset, sigoset;
347 size_t len;
348 mode_t mask;
349 u_short smask;
350
351 #ifdef KERN_PROC_UMASK
352 /*
353 * First try requesting the umask without temporarily modifying it.
354 * Note that this does not work if the sysctl
355 * security.bsd.unprivileged_proc_debug is set to 0.
356 */
357 len = sizeof(smask);
358 if (sysctl((int[4]){ CTL_KERN, KERN_PROC, KERN_PROC_UMASK, 0 },
359 4, &smask, &len, NULL, 0) == 0)
360 return (smask);
361 #endif
362 /*
363 * Since it's possible that the caller is opening files inside a signal
364 * handler, protect them as best we can.
365 */
366 sigfillset(&sigset);
367 (void)__libc_sigprocmask(SIG_BLOCK, &sigset, &sigoset);
368 (void)umask(mask = umask(0));
369 (void)__libc_sigprocmask(SIG_SETMASK, &sigoset, NULL);
370 return (mask);
371 }
372
373 static BITCMD *
addcmd(BITCMD * set,mode_t op,mode_t who,mode_t oparg,mode_t mask)374 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
375 {
376 switch (op) {
377 case '=':
378 set->cmd = '-';
379 set->bits = who ? who : STANDARD_BITS;
380 set++;
381
382 op = '+';
383 /* FALLTHROUGH */
384 case '+':
385 case '-':
386 case 'X':
387 set->cmd = op;
388 set->bits = (who ? who : mask) & oparg;
389 break;
390
391 case 'u':
392 case 'g':
393 case 'o':
394 set->cmd = op;
395 if (who) {
396 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
397 ((who & S_IRGRP) ? CMD2_GBITS : 0) |
398 ((who & S_IROTH) ? CMD2_OBITS : 0);
399 set->bits = (mode_t)~0;
400 } else {
401 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
402 set->bits = mask;
403 }
404
405 if (oparg == '+')
406 set->cmd2 |= CMD2_SET;
407 else if (oparg == '-')
408 set->cmd2 |= CMD2_CLR;
409 else if (oparg == '=')
410 set->cmd2 |= CMD2_SET|CMD2_CLR;
411 break;
412 }
413 return (set + 1);
414 }
415
416 #ifdef SETMODE_DEBUG
417 static void
dumpmode(BITCMD * set)418 dumpmode(BITCMD *set)
419 {
420 for (; set->cmd; ++set)
421 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
422 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
423 set->cmd2 & CMD2_CLR ? " CLR" : "",
424 set->cmd2 & CMD2_SET ? " SET" : "",
425 set->cmd2 & CMD2_UBITS ? " UBITS" : "",
426 set->cmd2 & CMD2_GBITS ? " GBITS" : "",
427 set->cmd2 & CMD2_OBITS ? " OBITS" : "");
428 }
429 #endif
430
431 /*
432 * Given an array of bitcmd structures, compress by compacting consecutive
433 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u',
434 * 'g' and 'o' commands continue to be separate. They could probably be
435 * compacted, but it's not worth the effort.
436 */
437 static void
compress_mode(BITCMD * set)438 compress_mode(BITCMD *set)
439 {
440 BITCMD *nset;
441 int setbits, clrbits, Xbits, op;
442
443 for (nset = set;;) {
444 /* Copy over any 'u', 'g' and 'o' commands. */
445 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
446 *set++ = *nset++;
447 if (!op)
448 return;
449 }
450
451 for (setbits = clrbits = Xbits = 0;; nset++) {
452 if ((op = nset->cmd) == '-') {
453 clrbits |= nset->bits;
454 setbits &= ~nset->bits;
455 Xbits &= ~nset->bits;
456 } else if (op == '+') {
457 setbits |= nset->bits;
458 clrbits &= ~nset->bits;
459 Xbits &= ~nset->bits;
460 } else if (op == 'X')
461 Xbits |= nset->bits & ~setbits;
462 else
463 break;
464 }
465 if (clrbits) {
466 set->cmd = '-';
467 set->cmd2 = 0;
468 set->bits = clrbits;
469 set++;
470 }
471 if (setbits) {
472 set->cmd = '+';
473 set->cmd2 = 0;
474 set->bits = setbits;
475 set++;
476 }
477 if (Xbits) {
478 set->cmd = 'X';
479 set->cmd2 = 0;
480 set->bits = Xbits;
481 set++;
482 }
483 }
484 }
485