1/* $NetBSD: setmode.c,v 1.38 2022/04/19 20:32:15 rillig 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 38static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94"; 39#else 40__RCSID("$NetBSD: setmode.c,v 1.38 2022/04/19 20:32:15 rillig 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 68typedef 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 80static BITCMD *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t); 81static void compress_mode(BITCMD *); 82#ifdef SETMODE_DEBUG 83static 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 */ 92mode_t 93getmode(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; 120common: 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 errno = reallocarr(&newset, setlen, sizeof(*newset)); \ 168 if (errno) \ 169 goto out; \ 170 set = newset + (set - saveset); \ 171 saveset = newset; \ 172 endset = newset + (setlen - 2); \ 173 } \ 174 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d)); \ 175} while (0) 176 177#define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 178 179void * 180setmode(const char *p) 181{ 182 int serrno; 183 char op, *ep; 184 BITCMD *set, *saveset, *endset; 185 sigset_t signset, sigoset; 186 mode_t mask, perm, permXbits, who; 187 long lval; 188 int equalopdone = 0; /* pacify gcc */ 189 int setlen; 190 191 if (!*p) { 192 errno = EINVAL; 193 return NULL; 194 } 195 196 /* 197 * Get a copy of the mask for the permissions that are mask relative. 198 * Flip the bits, we want what's not set. Since it's possible that 199 * the caller is opening files inside a signal handler, protect them 200 * as best we can. 201 */ 202 sigfillset(&signset); 203 (void)sigprocmask(SIG_BLOCK, &signset, &sigoset); 204 (void)umask(mask = umask(0)); 205 mask = ~mask; 206 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 207 208 setlen = SET_LEN + 2; 209 set = NULL; 210 errno = reallocarr(&set, setlen, sizeof(*set)); 211 if (errno) 212 return NULL; 213 saveset = set; 214 endset = set + (setlen - 2); 215 216 /* 217 * If an absolute number, get it and return; disallow non-octal digits 218 * or illegal bits. 219 */ 220 if (isdigit((unsigned char)*p)) { 221 errno = 0; 222 lval = strtol(p, &ep, 8); 223 if (*ep) { 224 errno = EINVAL; 225 goto out; 226 } 227 if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) 228 goto out; 229 if (lval & ~(STANDARD_BITS|S_ISTXT)) { 230 errno = EINVAL; 231 goto out; 232 } 233 perm = (mode_t)lval; 234 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 235 set->cmd = 0; 236 return (saveset); 237 } 238 239 /* 240 * Build list of structures to set/clear/copy bits as described by 241 * each clause of the symbolic mode. 242 */ 243 for (;;) { 244 /* First, find out which bits might be modified. */ 245 for (who = 0;; ++p) { 246 switch (*p) { 247 case 'a': 248 who |= STANDARD_BITS; 249 break; 250 case 'u': 251 who |= S_ISUID|S_IRWXU; 252 break; 253 case 'g': 254 who |= S_ISGID|S_IRWXG; 255 break; 256 case 'o': 257 who |= S_IRWXO; 258 break; 259 default: 260 goto getop; 261 } 262 } 263 264getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 265 errno = EINVAL; 266 goto out; 267 } 268 if (op == '=') 269 equalopdone = 0; 270 271 who &= ~S_ISTXT; 272 for (perm = 0, permXbits = 0;; ++p) { 273 switch (*p) { 274 case 'r': 275 perm |= S_IRUSR|S_IRGRP|S_IROTH; 276 break; 277 case 's': 278 /* 279 * If specific bits where requested and 280 * only "other" bits ignore set-id. 281 */ 282 if (who == 0 || (who & ~S_IRWXO)) 283 perm |= S_ISUID|S_ISGID; 284 break; 285 case 't': 286 /* 287 * If specific bits where requested and 288 * only "other" bits ignore set-id. 289 */ 290 if (who == 0 || (who & ~S_IRWXO)) { 291 who |= S_ISTXT; 292 perm |= S_ISTXT; 293 } 294 break; 295 case 'w': 296 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 297 break; 298 case 'X': 299 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 300 break; 301 case 'x': 302 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 303 break; 304 case 'u': 305 case 'g': 306 case 'o': 307 /* 308 * When ever we hit 'u', 'g', or 'o', we have 309 * to flush out any partial mode that we have, 310 * and then do the copying of the mode bits. 311 */ 312 if (perm) { 313 ADDCMD(op, who, perm, mask); 314 perm = 0; 315 } 316 if (op == '=') 317 equalopdone = 1; 318 if (op == '+' && permXbits) { 319 ADDCMD('X', who, permXbits, mask); 320 permXbits = 0; 321 } 322 ADDCMD(*p, who, op, mask); 323 break; 324 325 default: 326 /* 327 * Add any permissions that we haven't already 328 * done. 329 */ 330 if (perm || (op == '=' && !equalopdone)) { 331 if (op == '=') 332 equalopdone = 1; 333 ADDCMD(op, who, perm, mask); 334 perm = 0; 335 } 336 if (permXbits) { 337 ADDCMD('X', who, permXbits, mask); 338 permXbits = 0; 339 } 340 goto apply; 341 } 342 } 343 344apply: if (!*p) 345 break; 346 if (*p != ',') 347 goto getop; 348 ++p; 349 } 350 set->cmd = 0; 351#ifdef SETMODE_DEBUG 352 (void)printf("Before compress_mode()\n"); 353 dumpmode(saveset); 354#endif 355 compress_mode(saveset); 356#ifdef SETMODE_DEBUG 357 (void)printf("After compress_mode()\n"); 358 dumpmode(saveset); 359#endif 360 return (saveset); 361out: 362 serrno = errno; 363 free(saveset); 364 errno = serrno; 365 return NULL; 366} 367 368static BITCMD * 369addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask) 370{ 371 372 _DIAGASSERT(set != NULL); 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 415static void 416dumpmode(BITCMD *set) 417{ 418 419 _DIAGASSERT(set != NULL); 420 421 for (; set->cmd; ++set) 422 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 423 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 424 set->cmd2 & CMD2_CLR ? " CLR" : "", 425 set->cmd2 & CMD2_SET ? " SET" : "", 426 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 427 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 428 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 429} 430#endif 431 432/* 433 * Given an array of bitcmd structures, compress by compacting consecutive 434 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 435 * 'g' and 'o' commands continue to be separate. They could probably be 436 * compacted, but it's not worth the effort. 437 */ 438static void 439compress_mode(BITCMD *set) 440{ 441 BITCMD *nset; 442 int setbits, clrbits, Xbits, op; 443 444 _DIAGASSERT(set != NULL); 445 446 for (nset = set;;) { 447 /* Copy over any 'u', 'g' and 'o' commands. */ 448 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 449 *set++ = *nset++; 450 if (!op) 451 return; 452 } 453 454 for (setbits = clrbits = Xbits = 0;; nset++) { 455 if ((op = nset->cmd) == '-') { 456 clrbits |= nset->bits; 457 setbits &= ~nset->bits; 458 Xbits &= ~nset->bits; 459 } else if (op == '+') { 460 setbits |= nset->bits; 461 clrbits &= ~nset->bits; 462 Xbits &= ~nset->bits; 463 } else if (op == 'X') 464 Xbits |= nset->bits & ~setbits; 465 else 466 break; 467 } 468 if (clrbits) { 469 set->cmd = '-'; 470 set->cmd2 = 0; 471 set->bits = clrbits; 472 set++; 473 } 474 if (setbits) { 475 set->cmd = '+'; 476 set->cmd2 = 0; 477 set->bits = setbits; 478 set++; 479 } 480 if (Xbits) { 481 set->cmd = 'X'; 482 set->cmd2 = 0; 483 set->bits = Xbits; 484 set++; 485 } 486 } 487} 488