1 /* $NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos 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 #if defined(LIBC_SCCS) && !defined(lint) 40 #if 0 41 static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94"; 42 #else 43 static char rcsid[] = "$NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos Exp $"; 44 #endif 45 #endif /* LIBC_SCCS and not lint */ 46 47 #include <sys/types.h> 48 #include <sys/stat.h> 49 50 #include <ctype.h> 51 #include <errno.h> 52 #include <signal.h> 53 #include <stdlib.h> 54 #include <unistd.h> 55 56 #ifdef SETMODE_DEBUG 57 #include <stdio.h> 58 #endif 59 60 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 61 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 62 63 typedef struct bitcmd { 64 char cmd; 65 char cmd2; 66 mode_t bits; 67 } BITCMD; 68 69 #define CMD2_CLR 0x01 70 #define CMD2_SET 0x02 71 #define CMD2_GBITS 0x04 72 #define CMD2_OBITS 0x08 73 #define CMD2_UBITS 0x10 74 75 static BITCMD *addcmd __P((BITCMD *, int, int, int, u_int)); 76 static void compress_mode __P((BITCMD *)); 77 #ifdef SETMODE_DEBUG 78 static void dumpmode __P((BITCMD *)); 79 #endif 80 81 /* 82 * Given the old mode and an array of bitcmd structures, apply the operations 83 * described in the bitcmd structures to the old mode, and return the new mode. 84 * Note that there is no '=' command; a strict assignment is just a '-' (clear 85 * bits) followed by a '+' (set bits). 86 */ 87 mode_t 88 getmode(bbox, omode) 89 const void *bbox; 90 mode_t omode; 91 { 92 register const BITCMD *set; 93 register mode_t clrval, newmode, value; 94 95 set = (const BITCMD *)bbox; 96 newmode = omode; 97 for (value = 0;; set++) 98 switch(set->cmd) { 99 /* 100 * When copying the user, group or other bits around, we "know" 101 * where the bits are in the mode so that we can do shifts to 102 * copy them around. If we don't use shifts, it gets real 103 * grundgy with lots of single bit checks and bit sets. 104 */ 105 case 'u': 106 value = (newmode & S_IRWXU) >> 6; 107 goto common; 108 109 case 'g': 110 value = (newmode & S_IRWXG) >> 3; 111 goto common; 112 113 case 'o': 114 value = newmode & S_IRWXO; 115 common: if (set->cmd2 & CMD2_CLR) { 116 clrval = 117 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 118 if (set->cmd2 & CMD2_UBITS) 119 newmode &= ~((clrval<<6) & set->bits); 120 if (set->cmd2 & CMD2_GBITS) 121 newmode &= ~((clrval<<3) & set->bits); 122 if (set->cmd2 & CMD2_OBITS) 123 newmode &= ~(clrval & set->bits); 124 } 125 if (set->cmd2 & CMD2_SET) { 126 if (set->cmd2 & CMD2_UBITS) 127 newmode |= (value<<6) & set->bits; 128 if (set->cmd2 & CMD2_GBITS) 129 newmode |= (value<<3) & set->bits; 130 if (set->cmd2 & CMD2_OBITS) 131 newmode |= value & set->bits; 132 } 133 break; 134 135 case '+': 136 newmode |= set->bits; 137 break; 138 139 case '-': 140 newmode &= ~set->bits; 141 break; 142 143 case 'X': 144 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 145 newmode |= set->bits; 146 break; 147 148 case '\0': 149 default: 150 #ifdef SETMODE_DEBUG 151 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 152 #endif 153 return (newmode); 154 } 155 } 156 157 #define ADDCMD(a, b, c, d) \ 158 if (set >= endset) { \ 159 register BITCMD *newset; \ 160 setlen += SET_LEN_INCR; \ 161 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 162 if (!saveset) \ 163 return (NULL); \ 164 set = newset + (set - saveset); \ 165 saveset = newset; \ 166 endset = newset + (setlen - 2); \ 167 } \ 168 set = addcmd(set, (a), (b), (c), (d)) 169 170 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 171 172 void * 173 setmode(p) 174 register const char *p; 175 { 176 register int perm, who; 177 register char op; 178 BITCMD *set, *saveset, *endset; 179 sigset_t sigset, sigoset; 180 mode_t mask; 181 int equalopdone, permXbits, setlen; 182 183 if (!*p) 184 return (NULL); 185 186 /* 187 * Get a copy of the mask for the permissions that are mask relative. 188 * Flip the bits, we want what's not set. Since it's possible that 189 * the caller is opening files inside a signal handler, protect them 190 * as best we can. 191 */ 192 sigfillset(&sigset); 193 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 194 (void)umask(mask = umask(0)); 195 mask = ~mask; 196 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 197 198 setlen = SET_LEN + 2; 199 200 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 201 return (NULL); 202 saveset = set; 203 endset = set + (setlen - 2); 204 205 /* 206 * If an absolute number, get it and return; disallow non-octal digits 207 * or illegal bits. 208 */ 209 if (isdigit(*p)) { 210 perm = (mode_t)strtol(p, NULL, 8); 211 if (perm & ~(STANDARD_BITS|S_ISTXT)) { 212 free(saveset); 213 return (NULL); 214 } 215 while (*++p) 216 if (*p < '0' || *p > '7') { 217 free(saveset); 218 return (NULL); 219 } 220 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 221 return (saveset); 222 } 223 224 /* 225 * Build list of structures to set/clear/copy bits as described by 226 * each clause of the symbolic mode. 227 */ 228 for (;;) { 229 /* First, find out which bits might be modified. */ 230 for (who = 0;; ++p) { 231 switch (*p) { 232 case 'a': 233 who |= STANDARD_BITS; 234 break; 235 case 'u': 236 who |= S_ISUID|S_IRWXU; 237 break; 238 case 'g': 239 who |= S_ISGID|S_IRWXG; 240 break; 241 case 'o': 242 who |= S_IRWXO; 243 break; 244 default: 245 goto getop; 246 } 247 } 248 249 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 250 free(saveset); 251 return (NULL); 252 } 253 if (op == '=') 254 equalopdone = 0; 255 256 who &= ~S_ISTXT; 257 for (perm = 0, permXbits = 0;; ++p) { 258 switch (*p) { 259 case 'r': 260 perm |= S_IRUSR|S_IRGRP|S_IROTH; 261 break; 262 case 's': 263 /* 264 * If specific bits where requested and 265 * only "other" bits ignore set-id. 266 */ 267 if (who == 0 || (who & ~S_IRWXO)) 268 perm |= S_ISUID|S_ISGID; 269 break; 270 case 't': 271 /* 272 * If specific bits where requested and 273 * only "other" bits ignore set-id. 274 */ 275 if (who == 0 || (who & ~S_IRWXO)) { 276 who |= S_ISTXT; 277 perm |= S_ISTXT; 278 } 279 break; 280 case 'w': 281 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 282 break; 283 case 'X': 284 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 285 break; 286 case 'x': 287 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 288 break; 289 case 'u': 290 case 'g': 291 case 'o': 292 /* 293 * When ever we hit 'u', 'g', or 'o', we have 294 * to flush out any partial mode that we have, 295 * and then do the copying of the mode bits. 296 */ 297 if (perm) { 298 ADDCMD(op, who, perm, mask); 299 perm = 0; 300 } 301 if (op == '=') 302 equalopdone = 1; 303 if (op == '+' && permXbits) { 304 ADDCMD('X', who, permXbits, mask); 305 permXbits = 0; 306 } 307 ADDCMD(*p, who, op, mask); 308 break; 309 310 default: 311 /* 312 * Add any permissions that we haven't already 313 * done. 314 */ 315 if (perm || (op == '=' && !equalopdone)) { 316 if (op == '=') 317 equalopdone = 1; 318 ADDCMD(op, who, perm, mask); 319 perm = 0; 320 } 321 if (permXbits) { 322 ADDCMD('X', who, permXbits, mask); 323 permXbits = 0; 324 } 325 goto apply; 326 } 327 } 328 329 apply: if (!*p) 330 break; 331 if (*p != ',') 332 goto getop; 333 ++p; 334 } 335 set->cmd = 0; 336 #ifdef SETMODE_DEBUG 337 (void)printf("Before compress_mode()\n"); 338 dumpmode(saveset); 339 #endif 340 compress_mode(saveset); 341 #ifdef SETMODE_DEBUG 342 (void)printf("After compress_mode()\n"); 343 dumpmode(saveset); 344 #endif 345 return (saveset); 346 } 347 348 static BITCMD * 349 addcmd(set, op, who, oparg, mask) 350 BITCMD *set; 351 register int oparg, who; 352 register int op; 353 u_int mask; 354 { 355 switch (op) { 356 case '=': 357 set->cmd = '-'; 358 set->bits = who ? who : STANDARD_BITS; 359 set++; 360 361 op = '+'; 362 /* FALLTHROUGH */ 363 case '+': 364 case '-': 365 case 'X': 366 set->cmd = op; 367 set->bits = (who ? who : mask) & oparg; 368 break; 369 370 case 'u': 371 case 'g': 372 case 'o': 373 set->cmd = op; 374 if (who) { 375 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 376 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 377 ((who & S_IROTH) ? CMD2_OBITS : 0); 378 set->bits = ~0; 379 } else { 380 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 381 set->bits = mask; 382 } 383 384 if (oparg == '+') 385 set->cmd2 |= CMD2_SET; 386 else if (oparg == '-') 387 set->cmd2 |= CMD2_CLR; 388 else if (oparg == '=') 389 set->cmd2 |= CMD2_SET|CMD2_CLR; 390 break; 391 } 392 return (set + 1); 393 } 394 395 #ifdef SETMODE_DEBUG 396 static void 397 dumpmode(set) 398 register BITCMD *set; 399 { 400 for (; set->cmd; ++set) 401 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 402 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 403 set->cmd2 & CMD2_CLR ? " CLR" : "", 404 set->cmd2 & CMD2_SET ? " SET" : "", 405 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 406 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 407 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 408 } 409 #endif 410 411 /* 412 * Given an array of bitcmd structures, compress by compacting consecutive 413 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 414 * 'g' and 'o' commands continue to be separate. They could probably be 415 * compacted, but it's not worth the effort. 416 */ 417 static void 418 compress_mode(set) 419 register BITCMD *set; 420 { 421 register BITCMD *nset; 422 register int setbits, clrbits, Xbits, op; 423 424 for (nset = set;;) { 425 /* Copy over any 'u', 'g' and 'o' commands. */ 426 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 427 *set++ = *nset++; 428 if (!op) 429 return; 430 } 431 432 for (setbits = clrbits = Xbits = 0;; nset++) { 433 if ((op = nset->cmd) == '-') { 434 clrbits |= nset->bits; 435 setbits &= ~nset->bits; 436 Xbits &= ~nset->bits; 437 } else if (op == '+') { 438 setbits |= nset->bits; 439 clrbits &= ~nset->bits; 440 Xbits &= ~nset->bits; 441 } else if (op == 'X') 442 Xbits |= nset->bits & ~setbits; 443 else 444 break; 445 } 446 if (clrbits) { 447 set->cmd = '-'; 448 set->cmd2 = 0; 449 set->bits = clrbits; 450 set++; 451 } 452 if (setbits) { 453 set->cmd = '+'; 454 set->cmd2 = 0; 455 set->bits = setbits; 456 set++; 457 } 458 if (Xbits) { 459 set->cmd = 'X'; 460 set->cmd2 = 0; 461 set->bits = Xbits; 462 set++; 463 } 464 } 465 } 466