1 /* $OpenBSD: setmode.c,v 1.15 2004/07/02 13:58:06 otto Exp $ */ 2 /* $NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1989, 1993, 1994 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * Dave Borman at Cray Research, Inc. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 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 static char rcsid[] = "$OpenBSD: setmode.c,v 1.15 2004/07/02 13:58:06 otto Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/types.h> 45 #include <sys/stat.h> 46 47 #include <ctype.h> 48 #include <errno.h> 49 #include <signal.h> 50 #include <stdlib.h> 51 #include <unistd.h> 52 53 #ifdef SETMODE_DEBUG 54 #include <stdio.h> 55 #endif 56 57 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 58 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 59 60 typedef struct bitcmd { 61 char cmd; 62 char cmd2; 63 mode_t bits; 64 } BITCMD; 65 66 #define CMD2_CLR 0x01 67 #define CMD2_SET 0x02 68 #define CMD2_GBITS 0x04 69 #define CMD2_OBITS 0x08 70 #define CMD2_UBITS 0x10 71 72 static BITCMD *addcmd(BITCMD *, int, int, int, u_int); 73 static void compress_mode(BITCMD *); 74 #ifdef SETMODE_DEBUG 75 static void dumpmode(BITCMD *); 76 #endif 77 78 /* 79 * Given the old mode and an array of bitcmd structures, apply the operations 80 * described in the bitcmd structures to the old mode, and return the new mode. 81 * Note that there is no '=' command; a strict assignment is just a '-' (clear 82 * bits) followed by a '+' (set bits). 83 */ 84 mode_t 85 getmode(const void *bbox, mode_t omode) 86 { 87 const BITCMD *set; 88 mode_t clrval, newmode, value; 89 90 set = (const BITCMD *)bbox; 91 newmode = omode; 92 for (value = 0;; set++) 93 switch(set->cmd) { 94 /* 95 * When copying the user, group or other bits around, we "know" 96 * where the bits are in the mode so that we can do shifts to 97 * copy them around. If we don't use shifts, it gets real 98 * grundgy with lots of single bit checks and bit sets. 99 */ 100 case 'u': 101 value = (newmode & S_IRWXU) >> 6; 102 goto common; 103 104 case 'g': 105 value = (newmode & S_IRWXG) >> 3; 106 goto common; 107 108 case 'o': 109 value = newmode & S_IRWXO; 110 common: if (set->cmd2 & CMD2_CLR) { 111 clrval = 112 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 113 if (set->cmd2 & CMD2_UBITS) 114 newmode &= ~((clrval<<6) & set->bits); 115 if (set->cmd2 & CMD2_GBITS) 116 newmode &= ~((clrval<<3) & set->bits); 117 if (set->cmd2 & CMD2_OBITS) 118 newmode &= ~(clrval & set->bits); 119 } 120 if (set->cmd2 & CMD2_SET) { 121 if (set->cmd2 & CMD2_UBITS) 122 newmode |= (value<<6) & set->bits; 123 if (set->cmd2 & CMD2_GBITS) 124 newmode |= (value<<3) & set->bits; 125 if (set->cmd2 & CMD2_OBITS) 126 newmode |= value & set->bits; 127 } 128 break; 129 130 case '+': 131 newmode |= set->bits; 132 break; 133 134 case '-': 135 newmode &= ~set->bits; 136 break; 137 138 case 'X': 139 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 140 newmode |= set->bits; 141 break; 142 143 case '\0': 144 default: 145 #ifdef SETMODE_DEBUG 146 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 147 #endif 148 return (newmode); 149 } 150 } 151 152 #define ADDCMD(a, b, c, d) \ 153 if (set >= endset) { \ 154 BITCMD *newset; \ 155 setlen += SET_LEN_INCR; \ 156 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 157 if (newset == NULL) { \ 158 free(saveset); \ 159 return (NULL); \ 160 } \ 161 set = newset + (set - saveset); \ 162 saveset = newset; \ 163 endset = newset + (setlen - 2); \ 164 } \ 165 set = addcmd(set, (a), (b), (c), (d)) 166 167 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 168 169 void * 170 setmode(const char *p) 171 { 172 int perm, who; 173 char op, *ep; 174 BITCMD *set, *saveset, *endset; 175 sigset_t sigset, sigoset; 176 mode_t mask; 177 int equalopdone, permXbits, setlen; 178 u_long perml; 179 180 if (!*p) 181 return (NULL); 182 183 /* 184 * Get a copy of the mask for the permissions that are mask relative. 185 * Flip the bits, we want what's not set. Since it's possible that 186 * the caller is opening files inside a signal handler, protect them 187 * as best we can. 188 */ 189 sigfillset(&sigset); 190 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 191 (void)umask(mask = umask(0)); 192 mask = ~mask; 193 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 194 195 setlen = SET_LEN + 2; 196 197 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 198 return (NULL); 199 saveset = set; 200 endset = set + (setlen - 2); 201 202 /* 203 * If an absolute number, get it and return; disallow non-octal digits 204 * or illegal bits. 205 */ 206 if (isdigit(*p)) { 207 perml = strtoul(p, &ep, 8); 208 /* The test on perml will also catch overflow. */ 209 if (*ep != '\0' || (perml & ~(STANDARD_BITS|S_ISTXT))) { 210 errno = ERANGE; 211 free(saveset); 212 return (NULL); 213 } 214 perm = (mode_t)perml; 215 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 216 set->cmd = 0; 217 return (saveset); 218 } 219 220 /* 221 * Build list of structures to set/clear/copy bits as described by 222 * each clause of the symbolic mode. 223 */ 224 for (;;) { 225 /* First, find out which bits might be modified. */ 226 for (who = 0;; ++p) { 227 switch (*p) { 228 case 'a': 229 who |= STANDARD_BITS; 230 break; 231 case 'u': 232 who |= S_ISUID|S_IRWXU; 233 break; 234 case 'g': 235 who |= S_ISGID|S_IRWXG; 236 break; 237 case 'o': 238 who |= S_IRWXO; 239 break; 240 default: 241 goto getop; 242 } 243 } 244 245 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 246 free(saveset); 247 return (NULL); 248 } 249 if (op == '=') 250 equalopdone = 0; 251 252 who &= ~S_ISTXT; 253 for (perm = 0, permXbits = 0;; ++p) { 254 switch (*p) { 255 case 'r': 256 perm |= S_IRUSR|S_IRGRP|S_IROTH; 257 break; 258 case 's': 259 /* 260 * If specific bits where requested and 261 * only "other" bits ignore set-id. 262 */ 263 if (who == 0 || (who & ~S_IRWXO)) 264 perm |= S_ISUID|S_ISGID; 265 break; 266 case 't': 267 /* 268 * If specific bits where requested and 269 * only "other" bits ignore sticky. 270 */ 271 if (who == 0 || (who & ~S_IRWXO)) { 272 who |= S_ISTXT; 273 perm |= S_ISTXT; 274 } 275 break; 276 case 'w': 277 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 278 break; 279 case 'X': 280 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 281 break; 282 case 'x': 283 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 284 break; 285 case 'u': 286 case 'g': 287 case 'o': 288 /* 289 * When ever we hit 'u', 'g', or 'o', we have 290 * to flush out any partial mode that we have, 291 * and then do the copying of the mode bits. 292 */ 293 if (perm) { 294 ADDCMD(op, who, perm, mask); 295 perm = 0; 296 } 297 if (op == '=') 298 equalopdone = 1; 299 if (op == '+' && permXbits) { 300 ADDCMD('X', who, permXbits, mask); 301 permXbits = 0; 302 } 303 ADDCMD(*p, who, op, mask); 304 break; 305 306 default: 307 /* 308 * Add any permissions that we haven't already 309 * done. 310 */ 311 if (perm || (op == '=' && !equalopdone)) { 312 if (op == '=') 313 equalopdone = 1; 314 ADDCMD(op, who, perm, mask); 315 perm = 0; 316 } 317 if (permXbits) { 318 ADDCMD('X', who, permXbits, mask); 319 permXbits = 0; 320 } 321 goto apply; 322 } 323 } 324 325 apply: if (!*p) 326 break; 327 if (*p != ',') 328 goto getop; 329 ++p; 330 } 331 set->cmd = 0; 332 #ifdef SETMODE_DEBUG 333 (void)printf("Before compress_mode()\n"); 334 dumpmode(saveset); 335 #endif 336 compress_mode(saveset); 337 #ifdef SETMODE_DEBUG 338 (void)printf("After compress_mode()\n"); 339 dumpmode(saveset); 340 #endif 341 return (saveset); 342 } 343 344 static BITCMD * 345 addcmd(BITCMD *set, int op, int who, int oparg, u_int mask) 346 { 347 switch (op) { 348 case '=': 349 set->cmd = '-'; 350 set->bits = who ? who : STANDARD_BITS; 351 set++; 352 353 op = '+'; 354 /* FALLTHROUGH */ 355 case '+': 356 case '-': 357 case 'X': 358 set->cmd = op; 359 set->bits = (who ? who : mask) & oparg; 360 break; 361 362 case 'u': 363 case 'g': 364 case 'o': 365 set->cmd = op; 366 if (who) { 367 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 368 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 369 ((who & S_IROTH) ? CMD2_OBITS : 0); 370 set->bits = (mode_t)~0; 371 } else { 372 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 373 set->bits = mask; 374 } 375 376 if (oparg == '+') 377 set->cmd2 |= CMD2_SET; 378 else if (oparg == '-') 379 set->cmd2 |= CMD2_CLR; 380 else if (oparg == '=') 381 set->cmd2 |= CMD2_SET|CMD2_CLR; 382 break; 383 } 384 return (set + 1); 385 } 386 387 #ifdef SETMODE_DEBUG 388 static void 389 dumpmode(BITCMD *set) 390 { 391 for (; set->cmd; ++set) 392 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 393 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 394 set->cmd2 & CMD2_CLR ? " CLR" : "", 395 set->cmd2 & CMD2_SET ? " SET" : "", 396 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 397 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 398 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 399 } 400 #endif 401 402 /* 403 * Given an array of bitcmd structures, compress by compacting consecutive 404 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 405 * 'g' and 'o' commands continue to be separate. They could probably be 406 * compacted, but it's not worth the effort. 407 */ 408 static void 409 compress_mode(BITCMD *set) 410 { 411 BITCMD *nset; 412 int setbits, clrbits, Xbits, op; 413 414 for (nset = set;;) { 415 /* Copy over any 'u', 'g' and 'o' commands. */ 416 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 417 *set++ = *nset++; 418 if (!op) 419 return; 420 } 421 422 for (setbits = clrbits = Xbits = 0;; nset++) { 423 if ((op = nset->cmd) == '-') { 424 clrbits |= nset->bits; 425 setbits &= ~nset->bits; 426 Xbits &= ~nset->bits; 427 } else if (op == '+') { 428 setbits |= nset->bits; 429 clrbits &= ~nset->bits; 430 Xbits &= ~nset->bits; 431 } else if (op == 'X') 432 Xbits |= nset->bits & ~setbits; 433 else 434 break; 435 } 436 if (clrbits) { 437 set->cmd = '-'; 438 set->cmd2 = 0; 439 set->bits = clrbits; 440 set++; 441 } 442 if (setbits) { 443 set->cmd = '+'; 444 set->cmd2 = 0; 445 set->bits = setbits; 446 set++; 447 } 448 if (Xbits) { 449 set->cmd = 'X'; 450 set->cmd2 = 0; 451 set->bits = Xbits; 452 set++; 453 } 454 } 455 } 456