1 /* $NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94"; 43 #else 44 __RCSID("$NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 #include <sys/types.h> 50 #include <sys/stat.h> 51 52 #include <assert.h> 53 #include <ctype.h> 54 #include <errno.h> 55 #include <signal.h> 56 #include <stdlib.h> 57 #include <unistd.h> 58 59 #ifdef SETMODE_DEBUG 60 #include <stdio.h> 61 #endif 62 63 #ifdef __weak_alias 64 __weak_alias(getmode,_getmode) 65 __weak_alias(setmode,_setmode) 66 #endif 67 68 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 69 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 70 71 typedef struct bitcmd { 72 char cmd; 73 char cmd2; 74 mode_t bits; 75 } BITCMD; 76 77 #define CMD2_CLR 0x01 78 #define CMD2_SET 0x02 79 #define CMD2_GBITS 0x04 80 #define CMD2_OBITS 0x08 81 #define CMD2_UBITS 0x10 82 83 static BITCMD *addcmd __P((BITCMD *, int, int, int, u_int)); 84 static void compress_mode __P((BITCMD *)); 85 #ifdef SETMODE_DEBUG 86 static void dumpmode __P((BITCMD *)); 87 #endif 88 89 /* 90 * Given the old mode and an array of bitcmd structures, apply the operations 91 * described in the bitcmd structures to the old mode, and return the new mode. 92 * Note that there is no '=' command; a strict assignment is just a '-' (clear 93 * bits) followed by a '+' (set bits). 94 */ 95 mode_t 96 getmode(bbox, omode) 97 const void *bbox; 98 mode_t omode; 99 { 100 const BITCMD *set; 101 mode_t clrval, newmode, value; 102 103 _DIAGASSERT(bbox != NULL); 104 105 set = (const BITCMD *)bbox; 106 newmode = omode; 107 for (value = 0;; set++) 108 switch(set->cmd) { 109 /* 110 * When copying the user, group or other bits around, we "know" 111 * where the bits are in the mode so that we can do shifts to 112 * copy them around. If we don't use shifts, it gets real 113 * grundgy with lots of single bit checks and bit sets. 114 */ 115 case 'u': 116 value = (newmode & S_IRWXU) >> 6; 117 goto common; 118 119 case 'g': 120 value = (newmode & S_IRWXG) >> 3; 121 goto common; 122 123 case 'o': 124 value = newmode & S_IRWXO; 125 common: if (set->cmd2 & CMD2_CLR) { 126 clrval = 127 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 128 if (set->cmd2 & CMD2_UBITS) 129 newmode &= ~((clrval<<6) & set->bits); 130 if (set->cmd2 & CMD2_GBITS) 131 newmode &= ~((clrval<<3) & set->bits); 132 if (set->cmd2 & CMD2_OBITS) 133 newmode &= ~(clrval & set->bits); 134 } 135 if (set->cmd2 & CMD2_SET) { 136 if (set->cmd2 & CMD2_UBITS) 137 newmode |= (value<<6) & set->bits; 138 if (set->cmd2 & CMD2_GBITS) 139 newmode |= (value<<3) & set->bits; 140 if (set->cmd2 & CMD2_OBITS) 141 newmode |= value & set->bits; 142 } 143 break; 144 145 case '+': 146 newmode |= set->bits; 147 break; 148 149 case '-': 150 newmode &= ~set->bits; 151 break; 152 153 case 'X': 154 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 155 newmode |= set->bits; 156 break; 157 158 case '\0': 159 default: 160 #ifdef SETMODE_DEBUG 161 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 162 #endif 163 return (newmode); 164 } 165 } 166 167 #define ADDCMD(a, b, c, d) do { \ 168 if (set >= endset) { \ 169 BITCMD *newset; \ 170 setlen += SET_LEN_INCR; \ 171 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 172 if (newset == NULL) { \ 173 free(saveset); \ 174 return (NULL); \ 175 } \ 176 set = newset + (set - saveset); \ 177 saveset = newset; \ 178 endset = newset + (setlen - 2); \ 179 } \ 180 set = addcmd(set, (a), (b), (c), (d)); \ 181 } while (/*CONSTCOND*/0) 182 183 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 184 185 void * 186 setmode(p) 187 const char *p; 188 { 189 int perm, who; 190 char op, *ep; 191 BITCMD *set, *saveset, *endset; 192 sigset_t sigset, sigoset; 193 mode_t mask; 194 int equalopdone = 0; /* pacify gcc */ 195 int permXbits, setlen; 196 197 if (!*p) 198 return (NULL); 199 200 /* 201 * Get a copy of the mask for the permissions that are mask relative. 202 * Flip the bits, we want what's not set. Since it's possible that 203 * the caller is opening files inside a signal handler, protect them 204 * as best we can. 205 */ 206 sigfillset(&sigset); 207 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 208 (void)umask(mask = umask(0)); 209 mask = ~mask; 210 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 211 212 setlen = SET_LEN + 2; 213 214 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 215 return (NULL); 216 saveset = set; 217 endset = set + (setlen - 2); 218 219 /* 220 * If an absolute number, get it and return; disallow non-octal digits 221 * or illegal bits. 222 */ 223 if (isdigit((unsigned char)*p)) { 224 perm = (mode_t)strtol(p, &ep, 8); 225 if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) { 226 free(saveset); 227 return (NULL); 228 } 229 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 230 set->cmd = 0; 231 return (saveset); 232 } 233 234 /* 235 * Build list of structures to set/clear/copy bits as described by 236 * each clause of the symbolic mode. 237 */ 238 for (;;) { 239 /* First, find out which bits might be modified. */ 240 for (who = 0;; ++p) { 241 switch (*p) { 242 case 'a': 243 who |= STANDARD_BITS; 244 break; 245 case 'u': 246 who |= S_ISUID|S_IRWXU; 247 break; 248 case 'g': 249 who |= S_ISGID|S_IRWXG; 250 break; 251 case 'o': 252 who |= S_IRWXO; 253 break; 254 default: 255 goto getop; 256 } 257 } 258 259 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 260 free(saveset); 261 return (NULL); 262 } 263 if (op == '=') 264 equalopdone = 0; 265 266 who &= ~S_ISTXT; 267 for (perm = 0, permXbits = 0;; ++p) { 268 switch (*p) { 269 case 'r': 270 perm |= S_IRUSR|S_IRGRP|S_IROTH; 271 break; 272 case 's': 273 /* 274 * If specific bits where requested and 275 * only "other" bits ignore set-id. 276 */ 277 if (who == 0 || (who & ~S_IRWXO)) 278 perm |= S_ISUID|S_ISGID; 279 break; 280 case 't': 281 /* 282 * If specific bits where requested and 283 * only "other" bits ignore set-id. 284 */ 285 if (who == 0 || (who & ~S_IRWXO)) { 286 who |= S_ISTXT; 287 perm |= S_ISTXT; 288 } 289 break; 290 case 'w': 291 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 292 break; 293 case 'X': 294 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 295 break; 296 case 'x': 297 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 298 break; 299 case 'u': 300 case 'g': 301 case 'o': 302 /* 303 * When ever we hit 'u', 'g', or 'o', we have 304 * to flush out any partial mode that we have, 305 * and then do the copying of the mode bits. 306 */ 307 if (perm) { 308 ADDCMD(op, who, perm, mask); 309 perm = 0; 310 } 311 if (op == '=') 312 equalopdone = 1; 313 if (op == '+' && permXbits) { 314 ADDCMD('X', who, permXbits, mask); 315 permXbits = 0; 316 } 317 ADDCMD(*p, who, op, mask); 318 break; 319 320 default: 321 /* 322 * Add any permissions that we haven't already 323 * done. 324 */ 325 if (perm || (op == '=' && !equalopdone)) { 326 if (op == '=') 327 equalopdone = 1; 328 ADDCMD(op, who, perm, mask); 329 perm = 0; 330 } 331 if (permXbits) { 332 ADDCMD('X', who, permXbits, mask); 333 permXbits = 0; 334 } 335 goto apply; 336 } 337 } 338 339 apply: if (!*p) 340 break; 341 if (*p != ',') 342 goto getop; 343 ++p; 344 } 345 set->cmd = 0; 346 #ifdef SETMODE_DEBUG 347 (void)printf("Before compress_mode()\n"); 348 dumpmode(saveset); 349 #endif 350 compress_mode(saveset); 351 #ifdef SETMODE_DEBUG 352 (void)printf("After compress_mode()\n"); 353 dumpmode(saveset); 354 #endif 355 return (saveset); 356 } 357 358 static BITCMD * 359 addcmd(set, op, who, oparg, mask) 360 BITCMD *set; 361 int oparg, who; 362 int op; 363 u_int mask; 364 { 365 366 _DIAGASSERT(set != NULL); 367 368 switch (op) { 369 case '=': 370 set->cmd = '-'; 371 set->bits = who ? who : STANDARD_BITS; 372 set++; 373 374 op = '+'; 375 /* FALLTHROUGH */ 376 case '+': 377 case '-': 378 case 'X': 379 set->cmd = op; 380 set->bits = (who ? who : mask) & oparg; 381 break; 382 383 case 'u': 384 case 'g': 385 case 'o': 386 set->cmd = op; 387 if (who) { 388 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 389 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 390 ((who & S_IROTH) ? CMD2_OBITS : 0); 391 set->bits = (mode_t)~0; 392 } else { 393 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 394 set->bits = mask; 395 } 396 397 if (oparg == '+') 398 set->cmd2 |= CMD2_SET; 399 else if (oparg == '-') 400 set->cmd2 |= CMD2_CLR; 401 else if (oparg == '=') 402 set->cmd2 |= CMD2_SET|CMD2_CLR; 403 break; 404 } 405 return (set + 1); 406 } 407 408 #ifdef SETMODE_DEBUG 409 static void 410 dumpmode(set) 411 BITCMD *set; 412 { 413 414 _DIAGASSERT(set != NULL); 415 416 for (; set->cmd; ++set) 417 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 418 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 419 set->cmd2 & CMD2_CLR ? " CLR" : "", 420 set->cmd2 & CMD2_SET ? " SET" : "", 421 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 422 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 423 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 424 } 425 #endif 426 427 /* 428 * Given an array of bitcmd structures, compress by compacting consecutive 429 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 430 * 'g' and 'o' commands continue to be separate. They could probably be 431 * compacted, but it's not worth the effort. 432 */ 433 static void 434 compress_mode(set) 435 BITCMD *set; 436 { 437 BITCMD *nset; 438 int setbits, clrbits, Xbits, op; 439 440 _DIAGASSERT(set != NULL); 441 442 for (nset = set;;) { 443 /* Copy over any 'u', 'g' and 'o' commands. */ 444 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 445 *set++ = *nset++; 446 if (!op) 447 return; 448 } 449 450 for (setbits = clrbits = Xbits = 0;; nset++) { 451 if ((op = nset->cmd) == '-') { 452 clrbits |= nset->bits; 453 setbits &= ~nset->bits; 454 Xbits &= ~nset->bits; 455 } else if (op == '+') { 456 setbits |= nset->bits; 457 clrbits &= ~nset->bits; 458 Xbits &= ~nset->bits; 459 } else if (op == 'X') 460 Xbits |= nset->bits & ~setbits; 461 else 462 break; 463 } 464 if (clrbits) { 465 set->cmd = '-'; 466 set->cmd2 = 0; 467 set->bits = clrbits; 468 set++; 469 } 470 if (setbits) { 471 set->cmd = '+'; 472 set->cmd2 = 0; 473 set->bits = setbits; 474 set++; 475 } 476 if (Xbits) { 477 set->cmd = 'X'; 478 set->cmd2 = 0; 479 set->bits = Xbits; 480 set++; 481 } 482 } 483 } 484