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