1 /* 2 * Copyright (c) 1989, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Dave Borman at Cray Research, Inc. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "namespace.h" 40 #include <sys/types.h> 41 #include <sys/stat.h> 42 #include <sys/sysctl.h> 43 44 #include <ctype.h> 45 #include <errno.h> 46 #include <limits.h> 47 #include <signal.h> 48 #include <stddef.h> 49 #include <stdlib.h> 50 #include <unistd.h> 51 52 #ifdef SETMODE_DEBUG 53 #include <stdio.h> 54 #endif 55 #include "un-namespace.h" 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 mode_t getumask(void); 73 static BITCMD *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t); 74 static void compress_mode(BITCMD *); 75 #ifdef SETMODE_DEBUG 76 static void dumpmode(BITCMD *); 77 #endif 78 79 /* 80 * Given the old mode and an array of bitcmd structures, apply the operations 81 * described in the bitcmd structures to the old mode, and return the new mode. 82 * Note that there is no '=' command; a strict assignment is just a '-' (clear 83 * bits) followed by a '+' (set bits). 84 */ 85 mode_t 86 getmode(const void *bbox, mode_t omode) 87 { 88 const BITCMD *set; 89 mode_t clrval, newmode, value; 90 91 set = (const BITCMD *)bbox; 92 newmode = omode; 93 for (value = 0;; set++) 94 switch(set->cmd) { 95 /* 96 * When copying the user, group or other bits around, we "know" 97 * where the bits are in the mode so that we can do shifts to 98 * copy them around. If we don't use shifts, it gets real 99 * grundgy with lots of single bit checks and bit sets. 100 */ 101 case 'u': 102 value = (newmode & S_IRWXU) >> 6; 103 goto common; 104 105 case 'g': 106 value = (newmode & S_IRWXG) >> 3; 107 goto common; 108 109 case 'o': 110 value = newmode & S_IRWXO; 111 common: if (set->cmd2 & CMD2_CLR) { 112 clrval = 113 (set->cmd2 & CMD2_SET) ? S_IRWXO : value; 114 if (set->cmd2 & CMD2_UBITS) 115 newmode &= ~((clrval<<6) & set->bits); 116 if (set->cmd2 & CMD2_GBITS) 117 newmode &= ~((clrval<<3) & set->bits); 118 if (set->cmd2 & CMD2_OBITS) 119 newmode &= ~(clrval & set->bits); 120 } 121 if (set->cmd2 & CMD2_SET) { 122 if (set->cmd2 & CMD2_UBITS) 123 newmode |= (value<<6) & set->bits; 124 if (set->cmd2 & CMD2_GBITS) 125 newmode |= (value<<3) & set->bits; 126 if (set->cmd2 & CMD2_OBITS) 127 newmode |= value & set->bits; 128 } 129 break; 130 131 case '+': 132 newmode |= set->bits; 133 break; 134 135 case '-': 136 newmode &= ~set->bits; 137 break; 138 139 case 'X': 140 if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH)) 141 newmode |= set->bits; 142 break; 143 144 case '\0': 145 default: 146 #ifdef SETMODE_DEBUG 147 (void)printf("getmode:%04o -> %04o\n", omode, newmode); 148 #endif 149 return (newmode); 150 } 151 } 152 153 #define ADDCMD(a, b, c, d) \ 154 if (set >= endset) { \ 155 BITCMD *newset; \ 156 setlen += SET_LEN_INCR; \ 157 newset = realloc(saveset, sizeof(BITCMD) * setlen); \ 158 if (newset == NULL) \ 159 goto out; \ 160 set = newset + (set - saveset); \ 161 saveset = newset; \ 162 endset = newset + (setlen - 2); \ 163 } \ 164 set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d)) 165 166 #define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO) 167 168 void * 169 setmode(const char *p) 170 { 171 int serrno; 172 char op, *ep; 173 BITCMD *set, *saveset, *endset; 174 mode_t mask, perm, permXbits, who; 175 long perml; 176 int equalopdone; 177 int setlen; 178 179 if (!*p) { 180 errno = EINVAL; 181 return (NULL); 182 } 183 184 /* 185 * Get a copy of the mask for the permissions that are mask relative. 186 * Flip the bits, we want what's not set. 187 */ 188 mask = ~getumask(); 189 190 setlen = SET_LEN + 2; 191 192 if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL) 193 return (NULL); 194 saveset = set; 195 endset = set + (setlen - 2); 196 197 /* 198 * If an absolute number, get it and return; disallow non-octal digits 199 * or illegal bits. 200 */ 201 if (isdigit((unsigned char)*p)) { 202 errno = 0; 203 perml = strtol(p, &ep, 8); 204 if (*ep) { 205 errno = EINVAL; 206 goto out; 207 } 208 if (errno == ERANGE && (perml == LONG_MAX || perml == LONG_MIN)) 209 goto out; 210 if (perml & ~(STANDARD_BITS|S_ISTXT)) { 211 errno = EINVAL; 212 goto out; 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 equalopdone = 0; 225 for (;;) { 226 /* First, find out which bits might be modified. */ 227 for (who = 0;; ++p) { 228 switch (*p) { 229 case 'a': 230 who |= STANDARD_BITS; 231 break; 232 case 'u': 233 who |= S_ISUID|S_IRWXU; 234 break; 235 case 'g': 236 who |= S_ISGID|S_IRWXG; 237 break; 238 case 'o': 239 who |= S_IRWXO; 240 break; 241 default: 242 goto getop; 243 } 244 } 245 246 getop: if ((op = *p++) != '+' && op != '-' && op != '=') { 247 errno = EINVAL; 248 goto out; 249 } 250 if (op == '=') 251 equalopdone = 0; 252 253 who &= ~S_ISTXT; 254 for (perm = 0, permXbits = 0;; ++p) { 255 switch (*p) { 256 case 'r': 257 perm |= S_IRUSR|S_IRGRP|S_IROTH; 258 break; 259 case 's': 260 /* If only "other" bits ignore set-id. */ 261 if (!who || who & ~S_IRWXO) 262 perm |= S_ISUID|S_ISGID; 263 break; 264 case 't': 265 /* If only "other" bits ignore sticky. */ 266 if (!who || who & ~S_IRWXO) { 267 who |= S_ISTXT; 268 perm |= S_ISTXT; 269 } 270 break; 271 case 'w': 272 perm |= S_IWUSR|S_IWGRP|S_IWOTH; 273 break; 274 case 'X': 275 permXbits = S_IXUSR|S_IXGRP|S_IXOTH; 276 break; 277 case 'x': 278 perm |= S_IXUSR|S_IXGRP|S_IXOTH; 279 break; 280 case 'u': 281 case 'g': 282 case 'o': 283 /* 284 * When ever we hit 'u', 'g', or 'o', we have 285 * to flush out any partial mode that we have, 286 * and then do the copying of the mode bits. 287 */ 288 if (perm) { 289 ADDCMD(op, who, perm, mask); 290 perm = 0; 291 } 292 if (op == '=') 293 equalopdone = 1; 294 if (op == '+' && permXbits) { 295 ADDCMD('X', who, permXbits, mask); 296 permXbits = 0; 297 } 298 ADDCMD(*p, who, op, mask); 299 break; 300 301 default: 302 /* 303 * Add any permissions that we haven't already 304 * done. 305 */ 306 if (perm || (op == '=' && !equalopdone)) { 307 if (op == '=') 308 equalopdone = 1; 309 ADDCMD(op, who, perm, mask); 310 perm = 0; 311 } 312 if (permXbits) { 313 ADDCMD('X', who, permXbits, mask); 314 permXbits = 0; 315 } 316 goto apply; 317 } 318 } 319 320 apply: if (!*p) 321 break; 322 if (*p != ',') 323 goto getop; 324 ++p; 325 } 326 set->cmd = 0; 327 #ifdef SETMODE_DEBUG 328 (void)printf("Before compress_mode()\n"); 329 dumpmode(saveset); 330 #endif 331 compress_mode(saveset); 332 #ifdef SETMODE_DEBUG 333 (void)printf("After compress_mode()\n"); 334 dumpmode(saveset); 335 #endif 336 return (saveset); 337 out: 338 serrno = errno; 339 free(saveset); 340 errno = serrno; 341 return NULL; 342 } 343 344 static mode_t 345 getumask(void) 346 { 347 sigset_t sigset, sigoset; 348 size_t len; 349 mode_t mask; 350 u_short smask; 351 352 /* 353 * First try requesting the umask without temporarily modifying it. 354 * Note that this does not work if the sysctl 355 * security.bsd.unprivileged_proc_debug is set to 0. 356 */ 357 len = sizeof(smask); 358 if (sysctl((int[4]){ CTL_KERN, KERN_PROC, KERN_PROC_UMASK, getpid() }, 359 4, &smask, &len, NULL, 0) == 0) 360 return (smask); 361 362 /* 363 * Since it's possible that the caller is opening files inside a signal 364 * handler, protect them as best we can. 365 */ 366 sigfillset(&sigset); 367 (void)_sigprocmask(SIG_BLOCK, &sigset, &sigoset); 368 (void)umask(mask = umask(0)); 369 (void)_sigprocmask(SIG_SETMASK, &sigoset, NULL); 370 return (mask); 371 } 372 373 static BITCMD * 374 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask) 375 { 376 switch (op) { 377 case '=': 378 set->cmd = '-'; 379 set->bits = who ? who : STANDARD_BITS; 380 set++; 381 382 op = '+'; 383 /* FALLTHROUGH */ 384 case '+': 385 case '-': 386 case 'X': 387 set->cmd = op; 388 set->bits = (who ? who : mask) & oparg; 389 break; 390 391 case 'u': 392 case 'g': 393 case 'o': 394 set->cmd = op; 395 if (who) { 396 set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) | 397 ((who & S_IRGRP) ? CMD2_GBITS : 0) | 398 ((who & S_IROTH) ? CMD2_OBITS : 0); 399 set->bits = (mode_t)~0; 400 } else { 401 set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS; 402 set->bits = mask; 403 } 404 405 if (oparg == '+') 406 set->cmd2 |= CMD2_SET; 407 else if (oparg == '-') 408 set->cmd2 |= CMD2_CLR; 409 else if (oparg == '=') 410 set->cmd2 |= CMD2_SET|CMD2_CLR; 411 break; 412 } 413 return (set + 1); 414 } 415 416 #ifdef SETMODE_DEBUG 417 static void 418 dumpmode(BITCMD *set) 419 { 420 for (; set->cmd; ++set) 421 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n", 422 set->cmd, set->bits, set->cmd2 ? " cmd2:" : "", 423 set->cmd2 & CMD2_CLR ? " CLR" : "", 424 set->cmd2 & CMD2_SET ? " SET" : "", 425 set->cmd2 & CMD2_UBITS ? " UBITS" : "", 426 set->cmd2 & CMD2_GBITS ? " GBITS" : "", 427 set->cmd2 & CMD2_OBITS ? " OBITS" : ""); 428 } 429 #endif 430 431 /* 432 * Given an array of bitcmd structures, compress by compacting consecutive 433 * '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u', 434 * 'g' and 'o' commands continue to be separate. They could probably be 435 * compacted, but it's not worth the effort. 436 */ 437 static void 438 compress_mode(BITCMD *set) 439 { 440 BITCMD *nset; 441 int setbits, clrbits, Xbits, op; 442 443 for (nset = set;;) { 444 /* Copy over any 'u', 'g' and 'o' commands. */ 445 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') { 446 *set++ = *nset++; 447 if (!op) 448 return; 449 } 450 451 for (setbits = clrbits = Xbits = 0;; nset++) { 452 if ((op = nset->cmd) == '-') { 453 clrbits |= nset->bits; 454 setbits &= ~nset->bits; 455 Xbits &= ~nset->bits; 456 } else if (op == '+') { 457 setbits |= nset->bits; 458 clrbits &= ~nset->bits; 459 Xbits &= ~nset->bits; 460 } else if (op == 'X') 461 Xbits |= nset->bits & ~setbits; 462 else 463 break; 464 } 465 if (clrbits) { 466 set->cmd = '-'; 467 set->cmd2 = 0; 468 set->bits = clrbits; 469 set++; 470 } 471 if (setbits) { 472 set->cmd = '+'; 473 set->cmd2 = 0; 474 set->bits = setbits; 475 set++; 476 } 477 if (Xbits) { 478 set->cmd = 'X'; 479 set->cmd2 = 0; 480 set->bits = Xbits; 481 set++; 482 } 483 } 484 } 485