1 /* $NetBSD: setmode.c,v 1.36 2022/03/12 08:32:02 nia 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 1.36 2022/03/12 08:32:02 nia 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 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 = saveset; \ 167 if (reallocarr(&newset, setlen, sizeof(BITCMD)) != 0) { \ 168 errno = ENOMEM; \ 169 goto out; \ 170 } \ 171 set = newset + (set - saveset); \ 172 saveset = newset; \ 173 endset = newset + (setlen - 2); \ 174 } \ 175 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d)); \ 176 } while (/*CONSTCOND*/0) 177 178 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 179 180 void * 181 setmode(const char *p) 182 { 183 int serrno; 184 char op, *ep; 185 BITCMD *set, *saveset, *endset; 186 sigset_t signset, sigoset; 187 mode_t mask, perm, permXbits, who; 188 long lval; 189 int equalopdone = 0; /* pacify gcc */ 190 int setlen; 191 192 if (!*p) { 193 errno = EINVAL; 194 return NULL; 195 } 196 197 /* 198 * Get a copy of the mask for the permissions that are mask relative. 199 * Flip the bits, we want what's not set. Since it's possible that 200 * the caller is opening files inside a signal handler, protect them 201 * as best we can. 202 */ 203 sigfillset(&signset); 204 (void)sigprocmask(SIG_BLOCK, &signset, &sigoset); 205 (void)umask(mask = umask(0)); 206 mask = ~mask; 207 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 208 209 setlen = SET_LEN + 2; 210 set = NULL; 211 if (reallocarr(&set, setlen, sizeof(BITCMD)) != 0) { 212 errno = ENOMEM; 213 return (NULL); 214 } 215 saveset = set; 216 endset = set + (setlen - 2); 217 218 /* 219 * If an absolute number, get it and return; disallow non-octal digits 220 * or illegal bits. 221 */ 222 if (isdigit((unsigned char)*p)) { 223 errno = 0; 224 lval = strtol(p, &ep, 8); 225 if (*ep) { 226 errno = EINVAL; 227 goto out; 228 } 229 if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) 230 goto out; 231 if (lval & ~(STANDARD_BITS|S_ISTXT)) { 232 errno = EINVAL; 233 goto out; 234 } 235 perm = (mode_t)lval; 236 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 237 set->cmd = 0; 238 return (saveset); 239 } 240 241 /* 242 * Build list of structures to set/clear/copy bits as described by 243 * each clause of the symbolic mode. 244 */ 245 for (;;) { 246 /* First, find out which bits might be modified. */ 247 for (who = 0;; ++p) { 248 switch (*p) { 249 case 'a': 250 who |= STANDARD_BITS; 251 break; 252 case 'u': 253 who |= S_ISUID|S_IRWXU; 254 break; 255 case 'g': 256 who |= S_ISGID|S_IRWXG; 257 break; 258 case 'o': 259 who |= S_IRWXO; 260 break; 261 default: 262 goto getop; 263 } 264 } 265 266 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 267 errno = EINVAL; 268 goto out; 269 } 270 if (op == '=') 271 equalopdone = 0; 272 273 who &= ~S_ISTXT; 274 for (perm = 0, permXbits = 0;; ++p) { 275 switch (*p) { 276 case 'r': 277 perm |= S_IRUSR|S_IRGRP|S_IROTH; 278 break; 279 case 's': 280 /* 281 * If specific bits where requested and 282 * only "other" bits ignore set-id. 283 */ 284 if (who == 0 || (who & ~S_IRWXO)) 285 perm |= S_ISUID|S_ISGID; 286 break; 287 case 't': 288 /* 289 * If specific bits where requested and 290 * only "other" bits ignore set-id. 291 */ 292 if (who == 0 || (who & ~S_IRWXO)) { 293 who |= S_ISTXT; 294 perm |= S_ISTXT; 295 } 296 break; 297 case 'w': 298 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 299 break; 300 case 'X': 301 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 302 break; 303 case 'x': 304 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 305 break; 306 case 'u': 307 case 'g': 308 case 'o': 309 /* 310 * When ever we hit 'u', 'g', or 'o', we have 311 * to flush out any partial mode that we have, 312 * and then do the copying of the mode bits. 313 */ 314 if (perm) { 315 ADDCMD(op, who, perm, mask); 316 perm = 0; 317 } 318 if (op == '=') 319 equalopdone = 1; 320 if (op == '+' && permXbits) { 321 ADDCMD('X', who, permXbits, mask); 322 permXbits = 0; 323 } 324 ADDCMD(*p, who, op, mask); 325 break; 326 327 default: 328 /* 329 * Add any permissions that we haven't already 330 * done. 331 */ 332 if (perm || (op == '=' && !equalopdone)) { 333 if (op == '=') 334 equalopdone = 1; 335 ADDCMD(op, who, perm, mask); 336 perm = 0; 337 } 338 if (permXbits) { 339 ADDCMD('X', who, permXbits, mask); 340 permXbits = 0; 341 } 342 goto apply; 343 } 344 } 345 346 apply: if (!*p) 347 break; 348 if (*p != ',') 349 goto getop; 350 ++p; 351 } 352 set->cmd = 0; 353 #ifdef SETMODE_DEBUG 354 (void)printf("Before compress_mode()\n"); 355 dumpmode(saveset); 356 #endif 357 compress_mode(saveset); 358 #ifdef SETMODE_DEBUG 359 (void)printf("After compress_mode()\n"); 360 dumpmode(saveset); 361 #endif 362 return (saveset); 363 out: 364 serrno = errno; 365 free(saveset); 366 errno = serrno; 367 return NULL; 368 } 369 370 static BITCMD * 371 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask) 372 { 373 374 _DIAGASSERT(set != NULL); 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 418 dumpmode(BITCMD *set) 419 { 420 421 _DIAGASSERT(set != NULL); 422 423 for (; set->cmd; ++set) 424 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 425 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 426 set->cmd2 & CMD2_CLR ? " CLR" : "", 427 set->cmd2 & CMD2_SET ? " SET" : "", 428 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 429 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 430 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 431 } 432 #endif 433 434 /* 435 * Given an array of bitcmd structures, compress by compacting consecutive 436 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 437 * 'g' and 'o' commands continue to be separate. They could probably be 438 * compacted, but it's not worth the effort. 439 */ 440 static void 441 compress_mode(BITCMD *set) 442 { 443 BITCMD *nset; 444 int setbits, clrbits, Xbits, op; 445 446 _DIAGASSERT(set != NULL); 447 448 for (nset = set;;) { 449 /* Copy over any 'u', 'g' and 'o' commands. */ 450 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 451 *set++ = *nset++; 452 if (!op) 453 return; 454 } 455 456 for (setbits = clrbits = Xbits = 0;; nset++) { 457 if ((op = nset->cmd) == '-') { 458 clrbits |= nset->bits; 459 setbits &= ~nset->bits; 460 Xbits &= ~nset->bits; 461 } else if (op == '+') { 462 setbits |= nset->bits; 463 clrbits &= ~nset->bits; 464 Xbits &= ~nset->bits; 465 } else if (op == 'X') 466 Xbits |= nset->bits & ~setbits; 467 else 468 break; 469 } 470 if (clrbits) { 471 set->cmd = '-'; 472 set->cmd2 = 0; 473 set->bits = clrbits; 474 set++; 475 } 476 if (setbits) { 477 set->cmd = '+'; 478 set->cmd2 = 0; 479 set->bits = setbits; 480 set++; 481 } 482 if (Xbits) { 483 set->cmd = 'X'; 484 set->cmd2 = 0; 485 set->bits = Xbits; 486 set++; 487 } 488 } 489 } 490