1 /* $NetBSD: setmode.c,v 1.30 2003/08/07 16:42:56 agc 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 1.30 2003/08/07 16:42:56 agc 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 <unistd.h> 54 55 #ifdef SETMODE_DEBUG 56 #include <stdio.h> 57 #endif 58 59 #ifdef __weak_alias 60 __weak_alias(getmode,_getmode) 61 __weak_alias(setmode,_setmode) 62 #endif 63 64 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 65 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 66 67 typedef struct bitcmd { 68 char cmd; 69 char cmd2; 70 mode_t bits; 71 } BITCMD; 72 73 #define CMD2_CLR 0x01 74 #define CMD2_SET 0x02 75 #define CMD2_GBITS 0x04 76 #define CMD2_OBITS 0x08 77 #define CMD2_UBITS 0x10 78 79 static BITCMD *addcmd __P((BITCMD *, int, int, int, u_int)); 80 static void compress_mode __P((BITCMD *)); 81 #ifdef SETMODE_DEBUG 82 static void dumpmode __P((BITCMD *)); 83 #endif 84 85 /* 86 * Given the old mode and an array of bitcmd structures, apply the operations 87 * described in the bitcmd structures to the old mode, and return the new mode. 88 * Note that there is no '=' command; a strict assignment is just a '-' (clear 89 * bits) followed by a '+' (set bits). 90 */ 91 mode_t 92 getmode(bbox, omode) 93 const void *bbox; 94 mode_t omode; 95 { 96 const BITCMD *set; 97 mode_t clrval, newmode, value; 98 99 _DIAGASSERT(bbox != NULL); 100 101 set = (const BITCMD *)bbox; 102 newmode = omode; 103 for (value = 0;; set++) 104 switch(set->cmd) { 105 /* 106 * When copying the user, group or other bits around, we "know" 107 * where the bits are in the mode so that we can do shifts to 108 * copy them around. If we don't use shifts, it gets real 109 * grundgy with lots of single bit checks and bit sets. 110 */ 111 case 'u': 112 value = (newmode & S_IRWXU) >> 6; 113 goto common; 114 115 case 'g': 116 value = (newmode & S_IRWXG) >> 3; 117 goto common; 118 119 case 'o': 120 value = newmode & S_IRWXO; 121 common: if (set->cmd2 & CMD2_CLR) { 122 clrval = 123 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 124 if (set->cmd2 & CMD2_UBITS) 125 newmode &= ~((clrval<<6) & set->bits); 126 if (set->cmd2 & CMD2_GBITS) 127 newmode &= ~((clrval<<3) & set->bits); 128 if (set->cmd2 & CMD2_OBITS) 129 newmode &= ~(clrval & set->bits); 130 } 131 if (set->cmd2 & CMD2_SET) { 132 if (set->cmd2 & CMD2_UBITS) 133 newmode |= (value<<6) & set->bits; 134 if (set->cmd2 & CMD2_GBITS) 135 newmode |= (value<<3) & set->bits; 136 if (set->cmd2 & CMD2_OBITS) 137 newmode |= value & set->bits; 138 } 139 break; 140 141 case '+': 142 newmode |= set->bits; 143 break; 144 145 case '-': 146 newmode &= ~set->bits; 147 break; 148 149 case 'X': 150 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 151 newmode |= set->bits; 152 break; 153 154 case '\0': 155 default: 156 #ifdef SETMODE_DEBUG 157 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 158 #endif 159 return (newmode); 160 } 161 } 162 163 #define ADDCMD(a, b, c, d) do { \ 164 if (set >= endset) { \ 165 BITCMD *newset; \ 166 setlen += SET_LEN_INCR; \ 167 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 168 if (newset == NULL) { \ 169 free(saveset); \ 170 return (NULL); \ 171 } \ 172 set = newset + (set - saveset); \ 173 saveset = newset; \ 174 endset = newset + (setlen - 2); \ 175 } \ 176 set = addcmd(set, (a), (b), (c), (d)); \ 177 } while (/*CONSTCOND*/0) 178 179 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 180 181 void * 182 setmode(p) 183 const char *p; 184 { 185 int perm, who; 186 char op, *ep; 187 BITCMD *set, *saveset, *endset; 188 sigset_t signset, sigoset; 189 mode_t mask; 190 int equalopdone = 0; /* pacify gcc */ 191 int permXbits, setlen; 192 193 if (!*p) 194 return (NULL); 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; 209 210 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 211 return (NULL); 212 saveset = set; 213 endset = set + (setlen - 2); 214 215 /* 216 * If an absolute number, get it and return; disallow non-octal digits 217 * or illegal bits. 218 */ 219 if (isdigit((unsigned char)*p)) { 220 perm = (mode_t)strtol(p, &ep, 8); 221 if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) { 222 free(saveset); 223 return (NULL); 224 } 225 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 226 set->cmd = 0; 227 return (saveset); 228 } 229 230 /* 231 * Build list of structures to set/clear/copy bits as described by 232 * each clause of the symbolic mode. 233 */ 234 for (;;) { 235 /* First, find out which bits might be modified. */ 236 for (who = 0;; ++p) { 237 switch (*p) { 238 case 'a': 239 who |= STANDARD_BITS; 240 break; 241 case 'u': 242 who |= S_ISUID|S_IRWXU; 243 break; 244 case 'g': 245 who |= S_ISGID|S_IRWXG; 246 break; 247 case 'o': 248 who |= S_IRWXO; 249 break; 250 default: 251 goto getop; 252 } 253 } 254 255 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 256 free(saveset); 257 return (NULL); 258 } 259 if (op == '=') 260 equalopdone = 0; 261 262 who &= ~S_ISTXT; 263 for (perm = 0, permXbits = 0;; ++p) { 264 switch (*p) { 265 case 'r': 266 perm |= S_IRUSR|S_IRGRP|S_IROTH; 267 break; 268 case 's': 269 /* 270 * If specific bits where requested and 271 * only "other" bits ignore set-id. 272 */ 273 if (who == 0 || (who & ~S_IRWXO)) 274 perm |= S_ISUID|S_ISGID; 275 break; 276 case 't': 277 /* 278 * If specific bits where requested and 279 * only "other" bits ignore set-id. 280 */ 281 if (who == 0 || (who & ~S_IRWXO)) { 282 who |= S_ISTXT; 283 perm |= S_ISTXT; 284 } 285 break; 286 case 'w': 287 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 288 break; 289 case 'X': 290 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 291 break; 292 case 'x': 293 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 294 break; 295 case 'u': 296 case 'g': 297 case 'o': 298 /* 299 * When ever we hit 'u', 'g', or 'o', we have 300 * to flush out any partial mode that we have, 301 * and then do the copying of the mode bits. 302 */ 303 if (perm) { 304 ADDCMD(op, who, perm, mask); 305 perm = 0; 306 } 307 if (op == '=') 308 equalopdone = 1; 309 if (op == '+' && permXbits) { 310 ADDCMD('X', who, permXbits, mask); 311 permXbits = 0; 312 } 313 ADDCMD(*p, who, op, mask); 314 break; 315 316 default: 317 /* 318 * Add any permissions that we haven't already 319 * done. 320 */ 321 if (perm || (op == '=' && !equalopdone)) { 322 if (op == '=') 323 equalopdone = 1; 324 ADDCMD(op, who, perm, mask); 325 perm = 0; 326 } 327 if (permXbits) { 328 ADDCMD('X', who, permXbits, mask); 329 permXbits = 0; 330 } 331 goto apply; 332 } 333 } 334 335 apply: if (!*p) 336 break; 337 if (*p != ',') 338 goto getop; 339 ++p; 340 } 341 set->cmd = 0; 342 #ifdef SETMODE_DEBUG 343 (void)printf("Before compress_mode()\n"); 344 dumpmode(saveset); 345 #endif 346 compress_mode(saveset); 347 #ifdef SETMODE_DEBUG 348 (void)printf("After compress_mode()\n"); 349 dumpmode(saveset); 350 #endif 351 return (saveset); 352 } 353 354 static BITCMD * 355 addcmd(set, op, who, oparg, mask) 356 BITCMD *set; 357 int oparg, who; 358 int op; 359 u_int mask; 360 { 361 362 _DIAGASSERT(set != NULL); 363 364 switch (op) { 365 case '=': 366 set->cmd = '-'; 367 set->bits = who ? who : STANDARD_BITS; 368 set++; 369 370 op = '+'; 371 /* FALLTHROUGH */ 372 case '+': 373 case '-': 374 case 'X': 375 set->cmd = op; 376 set->bits = (who ? who : mask) & oparg; 377 break; 378 379 case 'u': 380 case 'g': 381 case 'o': 382 set->cmd = op; 383 if (who) { 384 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 385 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 386 ((who & S_IROTH) ? CMD2_OBITS : 0); 387 set->bits = (mode_t)~0; 388 } else { 389 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 390 set->bits = mask; 391 } 392 393 if (oparg == '+') 394 set->cmd2 |= CMD2_SET; 395 else if (oparg == '-') 396 set->cmd2 |= CMD2_CLR; 397 else if (oparg == '=') 398 set->cmd2 |= CMD2_SET|CMD2_CLR; 399 break; 400 } 401 return (set + 1); 402 } 403 404 #ifdef SETMODE_DEBUG 405 static void 406 dumpmode(set) 407 BITCMD *set; 408 { 409 410 _DIAGASSERT(set != NULL); 411 412 for (; set->cmd; ++set) 413 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 414 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 415 set->cmd2 & CMD2_CLR ? " CLR" : "", 416 set->cmd2 & CMD2_SET ? " SET" : "", 417 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 418 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 419 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 420 } 421 #endif 422 423 /* 424 * Given an array of bitcmd structures, compress by compacting consecutive 425 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 426 * 'g' and 'o' commands continue to be separate. They could probably be 427 * compacted, but it's not worth the effort. 428 */ 429 static void 430 compress_mode(set) 431 BITCMD *set; 432 { 433 BITCMD *nset; 434 int setbits, clrbits, Xbits, op; 435 436 _DIAGASSERT(set != NULL); 437 438 for (nset = set;;) { 439 /* Copy over any 'u', 'g' and 'o' commands. */ 440 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 441 *set++ = *nset++; 442 if (!op) 443 return; 444 } 445 446 for (setbits = clrbits = Xbits = 0;; nset++) { 447 if ((op = nset->cmd) == '-') { 448 clrbits |= nset->bits; 449 setbits &= ~nset->bits; 450 Xbits &= ~nset->bits; 451 } else if (op == '+') { 452 setbits |= nset->bits; 453 clrbits &= ~nset->bits; 454 Xbits &= ~nset->bits; 455 } else if (op == 'X') 456 Xbits |= nset->bits & ~setbits; 457 else 458 break; 459 } 460 if (clrbits) { 461 set->cmd = '-'; 462 set->cmd2 = 0; 463 set->bits = clrbits; 464 set++; 465 } 466 if (setbits) { 467 set->cmd = '+'; 468 set->cmd2 = 0; 469 set->bits = setbits; 470 set++; 471 } 472 if (Xbits) { 473 set->cmd = 'X'; 474 set->cmd2 = 0; 475 set->bits = Xbits; 476 set++; 477 } 478 } 479 } 480