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 __FBSDID("$FreeBSD$");
38
39 #include "namespace.h"
40 #include <sys/types.h>
41 #include <sys/stat.h>
42 #include <sys/sysctl.h>
43
44 #include <ctype.h>
45 #include <errno.h>
46 #include <limits.h>
47 #include <signal.h>
48 #include <stddef.h>
49 #include <stdlib.h>
50 #include <unistd.h>
51
52 #ifdef SETMODE_DEBUG
53 #include <stdio.h>
54 #endif
55 #include "un-namespace.h"
56 #include "libc_private.h"
57
58 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */
59 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */
60
61 typedef struct bitcmd {
62 char cmd;
63 char cmd2;
64 mode_t bits;
65 } BITCMD;
66
67 #define CMD2_CLR 0x01
68 #define CMD2_SET 0x02
69 #define CMD2_GBITS 0x04
70 #define CMD2_OBITS 0x08
71 #define CMD2_UBITS 0x10
72
73 static mode_t get_current_umask(void);
74 static BITCMD *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t);
75 static void compress_mode(BITCMD *);
76 #ifdef SETMODE_DEBUG
77 static void dumpmode(BITCMD *);
78 #endif
79
80 /*
81 * Given the old mode and an array of bitcmd structures, apply the operations
82 * described in the bitcmd structures to the old mode, and return the new mode.
83 * Note that there is no '=' command; a strict assignment is just a '-' (clear
84 * bits) followed by a '+' (set bits).
85 */
86 mode_t
getmode(const void * bbox,mode_t omode)87 getmode(const void *bbox, mode_t omode)
88 {
89 const BITCMD *set;
90 mode_t clrval, newmode, value;
91
92 set = (const BITCMD *)bbox;
93 newmode = omode;
94 for (value = 0;; set++)
95 switch(set->cmd) {
96 /*
97 * When copying the user, group or other bits around, we "know"
98 * where the bits are in the mode so that we can do shifts to
99 * copy them around. If we don't use shifts, it gets real
100 * grundgy with lots of single bit checks and bit sets.
101 */
102 case 'u':
103 value = (newmode & S_IRWXU) >> 6;
104 goto common;
105
106 case 'g':
107 value = (newmode & S_IRWXG) >> 3;
108 goto common;
109
110 case 'o':
111 value = newmode & S_IRWXO;
112 common: if (set->cmd2 & CMD2_CLR) {
113 clrval =
114 (set->cmd2 & CMD2_SET) ? S_IRWXO : value;
115 if (set->cmd2 & CMD2_UBITS)
116 newmode &= ~((clrval<<6) & set->bits);
117 if (set->cmd2 & CMD2_GBITS)
118 newmode &= ~((clrval<<3) & set->bits);
119 if (set->cmd2 & CMD2_OBITS)
120 newmode &= ~(clrval & set->bits);
121 }
122 if (set->cmd2 & CMD2_SET) {
123 if (set->cmd2 & CMD2_UBITS)
124 newmode |= (value<<6) & set->bits;
125 if (set->cmd2 & CMD2_GBITS)
126 newmode |= (value<<3) & set->bits;
127 if (set->cmd2 & CMD2_OBITS)
128 newmode |= value & set->bits;
129 }
130 break;
131
132 case '+':
133 newmode |= set->bits;
134 break;
135
136 case '-':
137 newmode &= ~set->bits;
138 break;
139
140 case 'X':
141 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
142 newmode |= set->bits;
143 break;
144
145 case '\0':
146 default:
147 #ifdef SETMODE_DEBUG
148 (void)printf("getmode:%04o -> %04o\n", omode, newmode);
149 #endif
150 return (newmode);
151 }
152 }
153
154 #define ADDCMD(a, b, c, d) \
155 if (set >= endset) { \
156 BITCMD *newset; \
157 setlen += SET_LEN_INCR; \
158 newset = reallocarray(saveset, setlen, sizeof(BITCMD)); \
159 if (newset == NULL) \
160 goto out; \
161 set = newset + (set - saveset); \
162 saveset = newset; \
163 endset = newset + (setlen - 2); \
164 } \
165 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d))
166
167 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
168
169 void *
setmode(const char * p)170 setmode(const char *p)
171 {
172 int serrno;
173 char op, *ep;
174 BITCMD *set, *saveset, *endset;
175 mode_t mask, perm, permXbits, who;
176 long perml;
177 int equalopdone;
178 u_int setlen;
179
180 if (!*p) {
181 errno = EINVAL;
182 return (NULL);
183 }
184
185 /*
186 * Get a copy of the mask for the permissions that are mask relative.
187 * Flip the bits, we want what's not set.
188 */
189 mask = ~get_current_umask();
190
191 setlen = SET_LEN + 2;
192
193 if ((set = malloc(setlen * sizeof(BITCMD))) == NULL)
194 return (NULL);
195 saveset = set;
196 endset = set + (setlen - 2);
197
198 /*
199 * If an absolute number, get it and return; disallow non-octal digits
200 * or illegal bits.
201 */
202 if (isdigit((unsigned char)*p)) {
203 errno = 0;
204 perml = strtol(p, &ep, 8);
205 if (*ep) {
206 errno = EINVAL;
207 goto out;
208 }
209 if (errno == ERANGE && (perml == LONG_MAX || perml == LONG_MIN))
210 goto out;
211 if (perml & ~(STANDARD_BITS|S_ISTXT)) {
212 errno = EINVAL;
213 goto out;
214 }
215 perm = (mode_t)perml;
216 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
217 set->cmd = 0;
218 return (saveset);
219 }
220
221 /*
222 * Build list of structures to set/clear/copy bits as described by
223 * each clause of the symbolic mode.
224 */
225 equalopdone = 0;
226 for (;;) {
227 /* First, find out which bits might be modified. */
228 for (who = 0;; ++p) {
229 switch (*p) {
230 case 'a':
231 who |= STANDARD_BITS;
232 break;
233 case 'u':
234 who |= S_ISUID|S_IRWXU;
235 break;
236 case 'g':
237 who |= S_ISGID|S_IRWXG;
238 break;
239 case 'o':
240 who |= S_IRWXO;
241 break;
242 default:
243 goto getop;
244 }
245 }
246
247 getop: if ((op = *p++) != '+' && op != '-' && op != '=') {
248 errno = EINVAL;
249 goto out;
250 }
251 if (op == '=')
252 equalopdone = 0;
253
254 who &= ~S_ISTXT;
255 for (perm = 0, permXbits = 0;; ++p) {
256 switch (*p) {
257 case 'r':
258 perm |= S_IRUSR|S_IRGRP|S_IROTH;
259 break;
260 case 's':
261 /* If only "other" bits ignore set-id. */
262 if (!who || who & ~S_IRWXO)
263 perm |= S_ISUID|S_ISGID;
264 break;
265 case 't':
266 /* If only "other" bits ignore sticky. */
267 if (!who || who & ~S_IRWXO) {
268 who |= S_ISTXT;
269 perm |= S_ISTXT;
270 }
271 break;
272 case 'w':
273 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
274 break;
275 case 'X':
276 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
277 break;
278 case 'x':
279 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
280 break;
281 case 'u':
282 case 'g':
283 case 'o':
284 /*
285 * When ever we hit 'u', 'g', or 'o', we have
286 * to flush out any partial mode that we have,
287 * and then do the copying of the mode bits.
288 */
289 if (perm) {
290 ADDCMD(op, who, perm, mask);
291 perm = 0;
292 }
293 if (op == '=')
294 equalopdone = 1;
295 if (op == '+' && permXbits) {
296 ADDCMD('X', who, permXbits, mask);
297 permXbits = 0;
298 }
299 ADDCMD(*p, who, op, mask);
300 break;
301
302 default:
303 /*
304 * Add any permissions that we haven't already
305 * done.
306 */
307 if (perm || (op == '=' && !equalopdone)) {
308 if (op == '=')
309 equalopdone = 1;
310 ADDCMD(op, who, perm, mask);
311 perm = 0;
312 }
313 if (permXbits) {
314 ADDCMD('X', who, permXbits, mask);
315 permXbits = 0;
316 }
317 goto apply;
318 }
319 }
320
321 apply: if (!*p)
322 break;
323 if (*p != ',')
324 goto getop;
325 ++p;
326 }
327 set->cmd = 0;
328 #ifdef SETMODE_DEBUG
329 (void)printf("Before compress_mode()\n");
330 dumpmode(saveset);
331 #endif
332 compress_mode(saveset);
333 #ifdef SETMODE_DEBUG
334 (void)printf("After compress_mode()\n");
335 dumpmode(saveset);
336 #endif
337 return (saveset);
338 out:
339 serrno = errno;
340 free(saveset);
341 errno = serrno;
342 return NULL;
343 }
344
345 static mode_t
get_current_umask(void)346 get_current_umask(void)
347 {
348 sigset_t sigset, sigoset;
349 size_t len;
350 mode_t mask;
351 u_short smask;
352
353 #ifdef KERN_PROC_UMASK
354 /*
355 * First try requesting the umask without temporarily modifying it.
356 * Note that this does not work if the sysctl
357 * security.bsd.unprivileged_proc_debug is set to 0.
358 */
359 len = sizeof(smask);
360 if (sysctl((int[4]){ CTL_KERN, KERN_PROC, KERN_PROC_UMASK, 0 },
361 4, &smask, &len, NULL, 0) == 0)
362 return (smask);
363 #endif
364 /*
365 * Since it's possible that the caller is opening files inside a signal
366 * handler, protect them as best we can.
367 */
368 sigfillset(&sigset);
369 (void)__libc_sigprocmask(SIG_BLOCK, &sigset, &sigoset);
370 (void)umask(mask = umask(0));
371 (void)__libc_sigprocmask(SIG_SETMASK, &sigoset, NULL);
372 return (mask);
373 }
374
375 static BITCMD *
addcmd(BITCMD * set,mode_t op,mode_t who,mode_t oparg,mode_t mask)376 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
377 {
378 switch (op) {
379 case '=':
380 set->cmd = '-';
381 set->bits = who ? who : STANDARD_BITS;
382 set++;
383
384 op = '+';
385 /* FALLTHROUGH */
386 case '+':
387 case '-':
388 case 'X':
389 set->cmd = op;
390 set->bits = (who ? who : mask) & oparg;
391 break;
392
393 case 'u':
394 case 'g':
395 case 'o':
396 set->cmd = op;
397 if (who) {
398 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
399 ((who & S_IRGRP) ? CMD2_GBITS : 0) |
400 ((who & S_IROTH) ? CMD2_OBITS : 0);
401 set->bits = (mode_t)~0;
402 } else {
403 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
404 set->bits = mask;
405 }
406
407 if (oparg == '+')
408 set->cmd2 |= CMD2_SET;
409 else if (oparg == '-')
410 set->cmd2 |= CMD2_CLR;
411 else if (oparg == '=')
412 set->cmd2 |= CMD2_SET|CMD2_CLR;
413 break;
414 }
415 return (set + 1);
416 }
417
418 #ifdef SETMODE_DEBUG
419 static void
dumpmode(BITCMD * set)420 dumpmode(BITCMD *set)
421 {
422 for (; set->cmd; ++set)
423 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
424 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
425 set->cmd2 & CMD2_CLR ? " CLR" : "",
426 set->cmd2 & CMD2_SET ? " SET" : "",
427 set->cmd2 & CMD2_UBITS ? " UBITS" : "",
428 set->cmd2 & CMD2_GBITS ? " GBITS" : "",
429 set->cmd2 & CMD2_OBITS ? " OBITS" : "");
430 }
431 #endif
432
433 /*
434 * Given an array of bitcmd structures, compress by compacting consecutive
435 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u',
436 * 'g' and 'o' commands continue to be separate. They could probably be
437 * compacted, but it's not worth the effort.
438 */
439 static void
compress_mode(BITCMD * set)440 compress_mode(BITCMD *set)
441 {
442 BITCMD *nset;
443 int setbits, clrbits, Xbits, op;
444
445 for (nset = set;;) {
446 /* Copy over any 'u', 'g' and 'o' commands. */
447 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
448 *set++ = *nset++;
449 if (!op)
450 return;
451 }
452
453 for (setbits = clrbits = Xbits = 0;; nset++) {
454 if ((op = nset->cmd) == '-') {
455 clrbits |= nset->bits;
456 setbits &= ~nset->bits;
457 Xbits &= ~nset->bits;
458 } else if (op == '+') {
459 setbits |= nset->bits;
460 clrbits &= ~nset->bits;
461 Xbits &= ~nset->bits;
462 } else if (op == 'X')
463 Xbits |= nset->bits & ~setbits;
464 else
465 break;
466 }
467 if (clrbits) {
468 set->cmd = '-';
469 set->cmd2 = 0;
470 set->bits = clrbits;
471 set++;
472 }
473 if (setbits) {
474 set->cmd = '+';
475 set->cmd2 = 0;
476 set->bits = setbits;
477 set++;
478 }
479 if (Xbits) {
480 set->cmd = 'X';
481 set->cmd2 = 0;
482 set->bits = Xbits;
483 set++;
484 }
485 }
486 }
487