1 /* $OpenBSD: setmode.c,v 1.22 2014/10/11 04:14:35 deraadt 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 #include <sys/types.h> 37 #include <sys/stat.h> 38 39 #include <ctype.h> 40 #include <errno.h> 41 #include <signal.h> 42 #include <stdlib.h> 43 #include <unistd.h> 44 45 #ifdef SETMODE_DEBUG 46 #include <stdio.h> 47 #endif 48 49 #define SET_LEN 6 /* initial # of bitcmd struct to malloc */ 50 #define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */ 51 52 typedef struct bitcmd { 53 char cmd; 54 char cmd2; 55 mode_t bits; 56 } BITCMD; 57 58 #define CMD2_CLR 0x01 59 #define CMD2_SET 0x02 60 #define CMD2_GBITS 0x04 61 #define CMD2_OBITS 0x08 62 #define CMD2_UBITS 0x10 63 64 static BITCMD *addcmd(BITCMD *, int, int, int, u_int); 65 static void compress_mode(BITCMD *); 66 #ifdef SETMODE_DEBUG 67 static void dumpmode(BITCMD *); 68 #endif 69 70 /* 71 * Given the old mode and an array of bitcmd structures, apply the operations 72 * described in the bitcmd structures to the old mode, and return the new mode. 73 * Note that there is no '=' command; a strict assignment is just a '-' (clear 74 * bits) followed by a '+' (set bits). 75 */ 76 mode_t 77 getmode(const void *bbox, mode_t omode) 78 { 79 const BITCMD *set; 80 mode_t clrval, newmode, value; 81 82 set = (const BITCMD *)bbox; 83 newmode = omode; 84 for (value = 0;; set++) 85 switch(set->cmd) { 86 /* 87 * When copying the user, group or other bits around, we "know" 88 * where the bits are in the mode so that we can do shifts to 89 * copy them around. If we don't use shifts, it gets real 90 * grundgy with lots of single bit checks and bit sets. 91 */ 92 case 'u': 93 value = (newmode & S_IRWXU) >> 6; 94 goto common; 95 96 case 'g': 97 value = (newmode & S_IRWXG) >> 3; 98 goto common; 99 100 case 'o': 101 value = newmode & S_IRWXO; 102 common: if (set->cmd2 & CMD2_CLR) { 103 clrval = 104 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 105 if (set->cmd2 & CMD2_UBITS) 106 newmode &= ~((clrval<<6) & set->bits); 107 if (set->cmd2 & CMD2_GBITS) 108 newmode &= ~((clrval<<3) & set->bits); 109 if (set->cmd2 & CMD2_OBITS) 110 newmode &= ~(clrval & set->bits); 111 } 112 if (set->cmd2 & CMD2_SET) { 113 if (set->cmd2 & CMD2_UBITS) 114 newmode |= (value<<6) & set->bits; 115 if (set->cmd2 & CMD2_GBITS) 116 newmode |= (value<<3) & set->bits; 117 if (set->cmd2 & CMD2_OBITS) 118 newmode |= value & set->bits; 119 } 120 break; 121 122 case '+': 123 newmode |= set->bits; 124 break; 125 126 case '-': 127 newmode &= ~set->bits; 128 break; 129 130 case 'X': 131 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 132 newmode |= set->bits; 133 break; 134 135 case '\0': 136 default: 137 #ifdef SETMODE_DEBUG 138 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 139 #endif 140 return (newmode); 141 } 142 } 143 144 #define ADDCMD(a, b, c, d) \ 145 if (set >= endset) { \ 146 BITCMD *newset; \ 147 setlen += SET_LEN_INCR; \ 148 newset = reallocarray(saveset, setlen, sizeof(BITCMD)); \ 149 if (newset == NULL) { \ 150 free(saveset); \ 151 return (NULL); \ 152 } \ 153 set = newset + (set - saveset); \ 154 saveset = newset; \ 155 endset = newset + (setlen - 2); \ 156 } \ 157 set = addcmd(set, (a), (b), (c), (d)) 158 159 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 160 161 void * 162 setmode(const char *p) 163 { 164 char op, *ep; 165 BITCMD *set, *saveset, *endset; 166 sigset_t sigset, sigoset; 167 mode_t mask, perm, permXbits, who; 168 int equalopdone, setlen; 169 u_long perml; 170 171 if (!*p) { 172 errno = EINVAL; 173 return (NULL); 174 } 175 176 /* 177 * Get a copy of the mask for the permissions that are mask relative. 178 * Flip the bits, we want what's not set. Since it's possible that 179 * the caller is opening files inside a signal handler, protect them 180 * as best we can. 181 */ 182 sigfillset(&sigset); 183 (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset); 184 (void)umask(mask = umask(0)); 185 mask = ~mask; 186 (void)sigprocmask(SIG_SETMASK, &sigoset, NULL); 187 188 setlen = SET_LEN + 2; 189 190 if ((set = calloc((u_int)sizeof(BITCMD), setlen)) == NULL) 191 return (NULL); 192 saveset = set; 193 endset = set + (setlen - 2); 194 195 /* 196 * If an absolute number, get it and return; disallow non-octal digits 197 * or illegal bits. 198 */ 199 if (isdigit((unsigned char)*p)) { 200 perml = strtoul(p, &ep, 8); 201 /* The test on perml will also catch overflow. */ 202 if (*ep != '\0' || (perml & ~(STANDARD_BITS|S_ISTXT))) { 203 free(saveset); 204 errno = ERANGE; 205 return (NULL); 206 } 207 perm = (mode_t)perml; 208 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask); 209 set->cmd = 0; 210 return (saveset); 211 } 212 213 /* 214 * Build list of structures to set/clear/copy bits as described by 215 * each clause of the symbolic mode. 216 */ 217 for (;;) { 218 /* First, find out which bits might be modified. */ 219 for (who = 0;; ++p) { 220 switch (*p) { 221 case 'a': 222 who |= STANDARD_BITS; 223 break; 224 case 'u': 225 who |= S_ISUID|S_IRWXU; 226 break; 227 case 'g': 228 who |= S_ISGID|S_IRWXG; 229 break; 230 case 'o': 231 who |= S_IRWXO; 232 break; 233 default: 234 goto getop; 235 } 236 } 237 238 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 239 free(saveset); 240 errno = EINVAL; 241 return (NULL); 242 } 243 if (op == '=') 244 equalopdone = 0; 245 246 who &= ~S_ISTXT; 247 for (perm = 0, permXbits = 0;; ++p) { 248 switch (*p) { 249 case 'r': 250 perm |= S_IRUSR|S_IRGRP|S_IROTH; 251 break; 252 case 's': 253 /* 254 * If specific bits where requested and 255 * only "other" bits ignore set-id. 256 */ 257 if (who == 0 || (who & ~S_IRWXO)) 258 perm |= S_ISUID|S_ISGID; 259 break; 260 case 't': 261 /* 262 * If specific bits where requested and 263 * only "other" bits ignore sticky. 264 */ 265 if (who == 0 || (who & ~S_IRWXO)) { 266 who |= S_ISTXT; 267 perm |= S_ISTXT; 268 } 269 break; 270 case 'w': 271 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 272 break; 273 case 'X': 274 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 275 break; 276 case 'x': 277 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 278 break; 279 case 'u': 280 case 'g': 281 case 'o': 282 /* 283 * When ever we hit 'u', 'g', or 'o', we have 284 * to flush out any partial mode that we have, 285 * and then do the copying of the mode bits. 286 */ 287 if (perm) { 288 ADDCMD(op, who, perm, mask); 289 perm = 0; 290 } 291 if (op == '=') 292 equalopdone = 1; 293 if (op == '+' && permXbits) { 294 ADDCMD('X', who, permXbits, mask); 295 permXbits = 0; 296 } 297 ADDCMD(*p, who, op, mask); 298 break; 299 300 default: 301 /* 302 * Add any permissions that we haven't already 303 * done. 304 */ 305 if (perm || (op == '=' && !equalopdone)) { 306 if (op == '=') 307 equalopdone = 1; 308 ADDCMD(op, who, perm, mask); 309 perm = 0; 310 } 311 if (permXbits) { 312 ADDCMD('X', who, permXbits, mask); 313 permXbits = 0; 314 } 315 goto apply; 316 } 317 } 318 319 apply: if (!*p) 320 break; 321 if (*p != ',') 322 goto getop; 323 ++p; 324 } 325 set->cmd = 0; 326 #ifdef SETMODE_DEBUG 327 (void)printf("Before compress_mode()\n"); 328 dumpmode(saveset); 329 #endif 330 compress_mode(saveset); 331 #ifdef SETMODE_DEBUG 332 (void)printf("After compress_mode()\n"); 333 dumpmode(saveset); 334 #endif 335 return (saveset); 336 } 337 338 static BITCMD * 339 addcmd(BITCMD *set, int op, int who, int oparg, u_int mask) 340 { 341 switch (op) { 342 case '=': 343 set->cmd = '-'; 344 set->bits = who ? who : STANDARD_BITS; 345 set++; 346 347 op = '+'; 348 /* FALLTHROUGH */ 349 case '+': 350 case '-': 351 case 'X': 352 set->cmd = op; 353 set->bits = (who ? who : mask) & oparg; 354 break; 355 356 case 'u': 357 case 'g': 358 case 'o': 359 set->cmd = op; 360 if (who) { 361 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 362 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 363 ((who & S_IROTH) ? CMD2_OBITS : 0); 364 set->bits = (mode_t)~0; 365 } else { 366 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 367 set->bits = mask; 368 } 369 370 if (oparg == '+') 371 set->cmd2 |= CMD2_SET; 372 else if (oparg == '-') 373 set->cmd2 |= CMD2_CLR; 374 else if (oparg == '=') 375 set->cmd2 |= CMD2_SET|CMD2_CLR; 376 break; 377 } 378 return (set + 1); 379 } 380 381 #ifdef SETMODE_DEBUG 382 static void 383 dumpmode(BITCMD *set) 384 { 385 for (; set->cmd; ++set) 386 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 387 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 388 set->cmd2 & CMD2_CLR ? " CLR" : "", 389 set->cmd2 & CMD2_SET ? " SET" : "", 390 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 391 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 392 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 393 } 394 #endif 395 396 /* 397 * Given an array of bitcmd structures, compress by compacting consecutive 398 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 399 * 'g' and 'o' commands continue to be separate. They could probably be 400 * compacted, but it's not worth the effort. 401 */ 402 static void 403 compress_mode(BITCMD *set) 404 { 405 BITCMD *nset; 406 int setbits, clrbits, Xbits, op; 407 408 for (nset = set;;) { 409 /* Copy over any 'u', 'g' and 'o' commands. */ 410 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 411 *set++ = *nset++; 412 if (!op) 413 return; 414 } 415 416 for (setbits = clrbits = Xbits = 0;; nset++) { 417 if ((op = nset->cmd) == '-') { 418 clrbits |= nset->bits; 419 setbits &= ~nset->bits; 420 Xbits &= ~nset->bits; 421 } else if (op == '+') { 422 setbits |= nset->bits; 423 clrbits &= ~nset->bits; 424 Xbits &= ~nset->bits; 425 } else if (op == 'X') 426 Xbits |= nset->bits & ~setbits; 427 else 428 break; 429 } 430 if (clrbits) { 431 set->cmd = '-'; 432 set->cmd2 = 0; 433 set->bits = clrbits; 434 set++; 435 } 436 if (setbits) { 437 set->cmd = '+'; 438 set->cmd2 = 0; 439 set->bits = setbits; 440 set++; 441 } 442 if (Xbits) { 443 set->cmd = 'X'; 444 set->cmd2 = 0; 445 set->bits = Xbits; 446 set++; 447 } 448 } 449 } 450