1 /* $NetBSD: setmode.c,v 1.23 1999/09/20 04:39:05 lukem 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 1.23 1999/09/20 04:39:05 lukem 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) \ 168 if (set >= endset) { \ 169 BITCMD *newset; \ 170 setlen += SET_LEN_INCR; \ 171 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 172 if (!saveset) \ 173 return (NULL); \ 174 set = newset + (set - saveset); \ 175 saveset = newset; \ 176 endset = newset + (setlen - 2); \ 177 } \ 178 set = addcmd(set, (a), (b), (c), (d)) 179 180 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 181 182 void * 183 setmode(p) 184 const char *p; 185 { 186 int perm, who; 187 char op; 188 BITCMD *set, *saveset, *endset; 189 sigset_t sigset, sigoset; 190 mode_t mask; 191 int equalopdone = 0; /* pacify gcc */ 192 int permXbits, setlen; 193 194 if (!*p) 195 return (NULL); 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(&sigset); 204 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 205 (void)umask(mask = umask(0)); 206 mask = ~mask; 207 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 208 209 setlen = SET_LEN + 2; 210 211 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 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 perm = (mode_t)strtol(p, NULL, 8); 222 if (perm & ~(STANDARD_BITS|S_ISTXT)) { 223 free(saveset); 224 return (NULL); 225 } 226 while (*++p) 227 if (*p < '0' || *p > '7') { 228 free(saveset); 229 return (NULL); 230 } 231 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 232 set->cmd = 0; 233 return (saveset); 234 } 235 236 /* 237 * Build list of structures to set/clear/copy bits as described by 238 * each clause of the symbolic mode. 239 */ 240 for (;;) { 241 /* First, find out which bits might be modified. */ 242 for (who = 0;; ++p) { 243 switch (*p) { 244 case 'a': 245 who |= STANDARD_BITS; 246 break; 247 case 'u': 248 who |= S_ISUID|S_IRWXU; 249 break; 250 case 'g': 251 who |= S_ISGID|S_IRWXG; 252 break; 253 case 'o': 254 who |= S_IRWXO; 255 break; 256 default: 257 goto getop; 258 } 259 } 260 261 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 262 free(saveset); 263 return (NULL); 264 } 265 if (op == '=') 266 equalopdone = 0; 267 268 who &= ~S_ISTXT; 269 for (perm = 0, permXbits = 0;; ++p) { 270 switch (*p) { 271 case 'r': 272 perm |= S_IRUSR|S_IRGRP|S_IROTH; 273 break; 274 case 's': 275 /* 276 * If specific bits where requested and 277 * only "other" bits ignore set-id. 278 */ 279 if (who == 0 || (who & ~S_IRWXO)) 280 perm |= S_ISUID|S_ISGID; 281 break; 282 case 't': 283 /* 284 * If specific bits where requested and 285 * only "other" bits ignore set-id. 286 */ 287 if (who == 0 || (who & ~S_IRWXO)) { 288 who |= S_ISTXT; 289 perm |= S_ISTXT; 290 } 291 break; 292 case 'w': 293 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 294 break; 295 case 'X': 296 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 297 break; 298 case 'x': 299 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 300 break; 301 case 'u': 302 case 'g': 303 case 'o': 304 /* 305 * When ever we hit 'u', 'g', or 'o', we have 306 * to flush out any partial mode that we have, 307 * and then do the copying of the mode bits. 308 */ 309 if (perm) { 310 ADDCMD(op, who, perm, mask); 311 perm = 0; 312 } 313 if (op == '=') 314 equalopdone = 1; 315 if (op == '+' && permXbits) { 316 ADDCMD('X', who, permXbits, mask); 317 permXbits = 0; 318 } 319 ADDCMD(*p, who, op, mask); 320 break; 321 322 default: 323 /* 324 * Add any permissions that we haven't already 325 * done. 326 */ 327 if (perm || (op == '=' && !equalopdone)) { 328 if (op == '=') 329 equalopdone = 1; 330 ADDCMD(op, who, perm, mask); 331 perm = 0; 332 } 333 if (permXbits) { 334 ADDCMD('X', who, permXbits, mask); 335 permXbits = 0; 336 } 337 goto apply; 338 } 339 } 340 341 apply: if (!*p) 342 break; 343 if (*p != ',') 344 goto getop; 345 ++p; 346 } 347 set->cmd = 0; 348 #ifdef SETMODE_DEBUG 349 (void)printf("Before compress_mode()\n"); 350 dumpmode(saveset); 351 #endif 352 compress_mode(saveset); 353 #ifdef SETMODE_DEBUG 354 (void)printf("After compress_mode()\n"); 355 dumpmode(saveset); 356 #endif 357 return (saveset); 358 } 359 360 static BITCMD * 361 addcmd(set, op, who, oparg, mask) 362 BITCMD *set; 363 int oparg, who; 364 int op; 365 u_int mask; 366 { 367 368 _DIAGASSERT(set != NULL); 369 370 switch (op) { 371 case '=': 372 set->cmd = '-'; 373 set->bits = who ? who : STANDARD_BITS; 374 set++; 375 376 op = '+'; 377 /* FALLTHROUGH */ 378 case '+': 379 case '-': 380 case 'X': 381 set->cmd = op; 382 set->bits = (who ? who : mask) & oparg; 383 break; 384 385 case 'u': 386 case 'g': 387 case 'o': 388 set->cmd = op; 389 if (who) { 390 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 391 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 392 ((who & S_IROTH) ? CMD2_OBITS : 0); 393 set->bits = (mode_t)~0; 394 } else { 395 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 396 set->bits = mask; 397 } 398 399 if (oparg == '+') 400 set->cmd2 |= CMD2_SET; 401 else if (oparg == '-') 402 set->cmd2 |= CMD2_CLR; 403 else if (oparg == '=') 404 set->cmd2 |= CMD2_SET|CMD2_CLR; 405 break; 406 } 407 return (set + 1); 408 } 409 410 #ifdef SETMODE_DEBUG 411 static void 412 dumpmode(set) 413 BITCMD *set; 414 { 415 416 _DIAGASSERT(set != NULL); 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 436 compress_mode(set) 437 BITCMD *set; 438 { 439 BITCMD *nset; 440 int setbits, clrbits, Xbits, op; 441 442 _DIAGASSERT(set != NULL); 443 444 for (nset = set;;) { 445 /* Copy over any 'u', 'g' and 'o' commands. */ 446 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 447 *set++ = *nset++; 448 if (!op) 449 return; 450 } 451 452 for (setbits = clrbits = Xbits = 0;; nset++) { 453 if ((op = nset->cmd) == '-') { 454 clrbits |= nset->bits; 455 setbits &= ~nset->bits; 456 Xbits &= ~nset->bits; 457 } else if (op == '+') { 458 setbits |= nset->bits; 459 clrbits &= ~nset->bits; 460 Xbits &= ~nset->bits; 461 } else if (op == 'X') 462 Xbits |= nset->bits & ~setbits; 463 else 464 break; 465 } 466 if (clrbits) { 467 set->cmd = '-'; 468 set->cmd2 = 0; 469 set->bits = clrbits; 470 set++; 471 } 472 if (setbits) { 473 set->cmd = '+'; 474 set->cmd2 = 0; 475 set->bits = setbits; 476 set++; 477 } 478 if (Xbits) { 479 set->cmd = 'X'; 480 set->cmd2 = 0; 481 set->bits = Xbits; 482 set++; 483 } 484 } 485 } 486