lib/libc/gen/setmode.c

   1 /*      $NetBSD: setmode.c,v 1.34 2012/06/25 22:32:43 abs 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. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  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 __RCSID("$NetBSD: setmode.c,v 1.34 2012/06/25 22:32:43 abs Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include "namespace.h"
  45 #include <sys/types.h>
  46 #include <sys/stat.h>
  47
  48 #include <assert.h>
  49 #include <ctype.h>
  50 #include <errno.h>
  51 #include <signal.h>
  52 #include <stdlib.h>
  53 #include <limits.h>
  54 #include <unistd.h>
  55
  56 #ifdef SETMODE_DEBUG
  57 #include <stdio.h>
  58 #endif
  59
  60 #ifdef __weak_alias
  61 __weak_alias(getmode,_getmode)
  62 __weak_alias(setmode,_setmode)
  63 #endif
  64
  65 #define SET_LEN 6               /* initial # of bitcmd struct to malloc */
  66 #define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */
  67
  68 typedef struct bitcmd {
  69         char    cmd;
  70         char    cmd2;
  71         mode_t  bits;
  72 } BITCMD;
  73
  74 #define CMD2_CLR        0x01
  75 #define CMD2_SET        0x02
  76 #define CMD2_GBITS      0x04
  77 #define CMD2_OBITS      0x08
  78 #define CMD2_UBITS      0x10
  79
  80 static BITCMD   *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t);
  81 static void      compress_mode(BITCMD *);
  82 #ifdef SETMODE_DEBUG
  83 static void      dumpmode(BITCMD *);
  84 #endif
  85
  86 /*
  87  * Given the old mode and an array of bitcmd structures, apply the operations
  88  * described in the bitcmd structures to the old mode, and return the new mode.
  89  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  90  * bits) followed by a '+' (set bits).
  91  */
  92 mode_t
  93 getmode(const void *bbox, mode_t omode)
  94 {
  95         const BITCMD *set;
  96         mode_t clrval, newmode, value;
  97
  98         _DIAGASSERT(bbox != NULL);
  99
 100         set = (const BITCMD *)bbox;
 101         newmode = omode;
 102         for (value = 0;; set++)
 103                 switch(set->cmd) {
 104                 /*
 105                  * When copying the user, group or other bits around, we "know"
 106                  * where the bits are in the mode so that we can do shifts to
 107                  * copy them around.  If we don't use shifts, it gets real
 108                  * grundgy with lots of single bit checks and bit sets.
 109                  */
 110                 case 'u':
 111                         value = (newmode & S_IRWXU) >> 6;
 112                         goto common;
 113
 114                 case 'g':
 115                         value = (newmode & S_IRWXG) >> 3;
 116                         goto common;
 117
 118                 case 'o':
 119                         value = newmode & S_IRWXO;
 120 common:                 if (set->cmd2 & CMD2_CLR) {
 121                                 clrval =
 122                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 123                                 if (set->cmd2 & CMD2_UBITS)
 124                                         newmode &= ~((clrval<<6) & set->bits);
 125                                 if (set->cmd2 & CMD2_GBITS)
 126                                         newmode &= ~((clrval<<3) & set->bits);
 127                                 if (set->cmd2 & CMD2_OBITS)
 128                                         newmode &= ~(clrval & set->bits);
 129                         }
 130                         if (set->cmd2 & CMD2_SET) {
 131                                 if (set->cmd2 & CMD2_UBITS)
 132                                         newmode |= (value<<6) & set->bits;
 133                                 if (set->cmd2 & CMD2_GBITS)
 134                                         newmode |= (value<<3) & set->bits;
 135                                 if (set->cmd2 & CMD2_OBITS)
 136                                         newmode |= value & set->bits;
 137                         }
 138                         break;
 139
 140                 case '+':
 141                         newmode |= set->bits;
 142                         break;
 143
 144                 case '-':
 145                         newmode &= ~set->bits;
 146                         break;
 147
 148                 case 'X':
 149                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 150                                 newmode |= set->bits;
 151                         break;
 152
 153                 case '\0':
 154                 default:
 155 #ifdef SETMODE_DEBUG
 156                         (void)printf("getmode:%04o -> %04o\n", omode, newmode);
 157 #endif
 158                         return (newmode);
 159                 }
 160 }
 161
 162 #define ADDCMD(a, b, c, d) do {                                         \
 163         if (set >= endset) {                                            \
 164                 BITCMD *newset;                                         \
 165                 setlen += SET_LEN_INCR;                                 \
 166                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 167                 if (newset == NULL)                                     \
 168                         goto out;                                       \
 169                 set = newset + (set - saveset);                         \
 170                 saveset = newset;                                       \
 171                 endset = newset + (setlen - 2);                         \
 172         }                                                               \
 173         set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d));  \
 174 } while (/*CONSTCOND*/0)
 175
 176 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 177
 178 void *
 179 setmode(const char *p)
 180 {
 181         int serrno;
 182         char op, *ep;
 183         BITCMD *set, *saveset, *endset;
 184         sigset_t signset, sigoset;
 185         mode_t mask, perm, permXbits, who;
 186         long lval;
 187         int equalopdone = 0;    /* pacify gcc */
 188         int setlen;
 189
 190         if (!*p) {
 191                 errno = EINVAL;
 192                 return NULL;
 193         }
 194
 195         /*
 196          * Get a copy of the mask for the permissions that are mask relative.
 197          * Flip the bits, we want what's not set.  Since it's possible that
 198          * the caller is opening files inside a signal handler, protect them
 199          * as best we can.
 200          */
 201         sigfillset(&signset);
 202         (void)sigprocmask(SIG_BLOCK, &signset, &sigoset);
 203         (void)umask(mask = umask(0));
 204         mask = ~mask;
 205         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
 206
 207         setlen = SET_LEN + 2;
 208
 209         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 210                 return (NULL);
 211         saveset = set;
 212         endset = set + (setlen - 2);
 213
 214         /*
 215          * If an absolute number, get it and return; disallow non-octal digits
 216          * or illegal bits.
 217          */
 218         if (isdigit((unsigned char)*p)) {
 219                 errno = 0;
 220                 lval = strtol(p, &ep, 8);
 221                 if (*ep) {
 222                         errno = EINVAL;
 223                         goto out;
 224                 }
 225                 if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
 226                         goto out;
 227                 if (lval & ~(STANDARD_BITS|S_ISTXT)) {
 228                         errno = EINVAL;
 229                         goto out;
 230                 }
 231                 perm = (mode_t)lval;
 232                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 233                 set->cmd = 0;
 234                 return (saveset);
 235         }
 236
 237         /*
 238          * Build list of structures to set/clear/copy bits as described by
 239          * each clause of the symbolic mode.
 240          */
 241         for (;;) {
 242                 /* First, find out which bits might be modified. */
 243                 for (who = 0;; ++p) {
 244                         switch (*p) {
 245                         case 'a':
 246                                 who |= STANDARD_BITS;
 247                                 break;
 248                         case 'u':
 249                                 who |= S_ISUID|S_IRWXU;
 250                                 break;
 251                         case 'g':
 252                                 who |= S_ISGID|S_IRWXG;
 253                                 break;
 254                         case 'o':
 255                                 who |= S_IRWXO;
 256                                 break;
 257                         default:
 258                                 goto getop;
 259                         }
 260                 }
 261
 262 getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
 263                         errno = EINVAL;
 264                         goto out;
 265                 }
 266                 if (op == '=')
 267                         equalopdone = 0;
 268
 269                 who &= ~S_ISTXT;
 270                 for (perm = 0, permXbits = 0;; ++p) {
 271                         switch (*p) {
 272                         case 'r':
 273                                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
 274                                 break;
 275                         case 's':
 276                                 /*
 277                                  * If specific bits where requested and
 278                                  * only "other" bits ignore set-id.
 279                                  */
 280                                 if (who == 0 || (who & ~S_IRWXO))
 281                                         perm |= S_ISUID|S_ISGID;
 282                                 break;
 283                         case 't':
 284                                 /*
 285                                  * If specific bits where requested and
 286                                  * only "other" bits ignore set-id.
 287                                  */
 288                                 if (who == 0 || (who & ~S_IRWXO)) {
 289                                         who |= S_ISTXT;
 290                                         perm |= S_ISTXT;
 291                                 }
 292                                 break;
 293                         case 'w':
 294                                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
 295                                 break;
 296                         case 'X':
 297                                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
 298                                 break;
 299                         case 'x':
 300                                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
 301                                 break;
 302                         case 'u':
 303                         case 'g':
 304                         case 'o':
 305                                 /*
 306                                  * When ever we hit 'u', 'g', or 'o', we have
 307                                  * to flush out any partial mode that we have,
 308                                  * and then do the copying of the mode bits.
 309                                  */
 310                                 if (perm) {
 311                                         ADDCMD(op, who, perm, mask);
 312                                         perm = 0;
 313                                 }
 314                                 if (op == '=')
 315                                         equalopdone = 1;
 316                                 if (op == '+' && permXbits) {
 317                                         ADDCMD('X', who, permXbits, mask);
 318                                         permXbits = 0;
 319                                 }
 320                                 ADDCMD(*p, who, op, mask);
 321                                 break;
 322
 323                         default:
 324                                 /*
 325                                  * Add any permissions that we haven't already
 326                                  * done.
 327                                  */
 328                                 if (perm || (op == '=' && !equalopdone)) {
 329                                         if (op == '=')
 330                                                 equalopdone = 1;
 331                                         ADDCMD(op, who, perm, mask);
 332                                         perm = 0;
 333                                 }
 334                                 if (permXbits) {
 335                                         ADDCMD('X', who, permXbits, mask);
 336                                         permXbits = 0;
 337                                 }
 338                                 goto apply;
 339                         }
 340                 }
 341
 342 apply:          if (!*p)
 343                         break;
 344                 if (*p != ',')
 345                         goto getop;
 346                 ++p;
 347         }
 348         set->cmd = 0;
 349 #ifdef SETMODE_DEBUG
 350         (void)printf("Before compress_mode()\n");
 351         dumpmode(saveset);
 352 #endif
 353         compress_mode(saveset);
 354 #ifdef SETMODE_DEBUG
 355         (void)printf("After compress_mode()\n");
 356         dumpmode(saveset);
 357 #endif
 358         return (saveset);
 359 out:
 360         serrno = errno;
 361         free(saveset);
 362         errno = serrno;
 363         return NULL;
 364 }
 365
 366 static BITCMD *
 367 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
 368 {
 369
 370         _DIAGASSERT(set != NULL);
 371
 372         switch (op) {
 373         case '=':
 374                 set->cmd = '-';
 375                 set->bits = who ? who : STANDARD_BITS;
 376                 set++;
 377
 378                 op = '+';
 379                 /* FALLTHROUGH */
 380         case '+':
 381         case '-':
 382         case 'X':
 383                 set->cmd = op;
 384                 set->bits = (who ? who : mask) & oparg;
 385                 break;
 386
 387         case 'u':
 388         case 'g':
 389         case 'o':
 390                 set->cmd = op;
 391                 if (who) {
 392                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 393                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 394                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 395                         set->bits = (mode_t)~0;
 396                 } else {
 397                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 398                         set->bits = mask;
 399                 }
 400
 401                 if (oparg == '+')
 402                         set->cmd2 |= CMD2_SET;
 403                 else if (oparg == '-')
 404                         set->cmd2 |= CMD2_CLR;
 405                 else if (oparg == '=')
 406                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 407                 break;
 408         }
 409         return (set + 1);
 410 }
 411
 412 #ifdef SETMODE_DEBUG
 413 static void
 414 dumpmode(BITCMD *set)
 415 {
 416
 417         _DIAGASSERT(set != NULL);
 418
 419         for (; set->cmd; ++set)
 420                 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 421                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 422                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 423                     set->cmd2 & CMD2_SET ? " SET" : "",
 424                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 425                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 426                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 427 }
 428 #endif
 429
 430 /*
 431  * Given an array of bitcmd structures, compress by compacting consecutive
 432  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 433  * 'g' and 'o' commands continue to be separate.  They could probably be
 434  * compacted, but it's not worth the effort.
 435  */
 436 static void
 437 compress_mode(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 }