lib/libc/gen/setmode.c

   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  * @(#)setmode.c        8.2 (Berkeley) 3/25/94
  33  * $FreeBSD: src/lib/libc/gen/setmode.c,v 1.11 2007/01/09 00:27:55 imp Exp $
  34  * $DragonFly: src/lib/libc/gen/setmode.c,v 1.7 2005/11/19 22:32:53 swildner Exp $
  35  */
  36
  37 #include "namespace.h"
  38 #include <sys/types.h>
  39 #include <sys/stat.h>
  40
  41 #include <ctype.h>
  42 #include <signal.h>
  43 #include <stddef.h>
  44 #include <stdlib.h>
  45 #include <unistd.h>
  46
  47 #ifdef SETMODE_DEBUG
  48 #include <stdio.h>
  49 #endif
  50 #include "un-namespace.h"
  51
  52 #define SET_LEN 6               /* initial # of bitcmd struct to malloc */
  53 #define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */
  54
  55 typedef struct bitcmd {
  56         char    cmd;
  57         char    cmd2;
  58         mode_t  bits;
  59 } BITCMD;
  60
  61 #define CMD2_CLR        0x01
  62 #define CMD2_SET        0x02
  63 #define CMD2_GBITS      0x04
  64 #define CMD2_OBITS      0x08
  65 #define CMD2_UBITS      0x10
  66
  67 static BITCMD   *addcmd(BITCMD *, int, int, int, u_int);
  68 static void      compress_mode(BITCMD *);
  69 #ifdef SETMODE_DEBUG
  70 static void      dumpmode(BITCMD *);
  71 #endif
  72
  73 /*
  74  * Given the old mode and an array of bitcmd structures, apply the operations
  75  * described in the bitcmd structures to the old mode, and return the new mode.
  76  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  77  * bits) followed by a '+' (set bits).
  78  */
  79 mode_t
  80 getmode(const void *bbox, mode_t omode)
  81 {
  82         const BITCMD *set;
  83         mode_t clrval, newmode, value;
  84
  85         set = (const BITCMD *)bbox;
  86         newmode = omode;
  87         for (value = 0;; set++)
  88                 switch(set->cmd) {
  89                 /*
  90                  * When copying the user, group or other bits around, we "know"
  91                  * where the bits are in the mode so that we can do shifts to
  92                  * copy them around.  If we don't use shifts, it gets real
  93                  * grundgy with lots of single bit checks and bit sets.
  94                  */
  95                 case 'u':
  96                         value = (newmode & S_IRWXU) >> 6;
  97                         goto common;
  98
  99                 case 'g':
 100                         value = (newmode & S_IRWXG) >> 3;
 101                         goto common;
 102
 103                 case 'o':
 104                         value = newmode & S_IRWXO;
 105 common:                 if (set->cmd2 & CMD2_CLR) {
 106                                 clrval =
 107                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 108                                 if (set->cmd2 & CMD2_UBITS)
 109                                         newmode &= ~((clrval<<6) & set->bits);
 110                                 if (set->cmd2 & CMD2_GBITS)
 111                                         newmode &= ~((clrval<<3) & set->bits);
 112                                 if (set->cmd2 & CMD2_OBITS)
 113                                         newmode &= ~(clrval & set->bits);
 114                         }
 115                         if (set->cmd2 & CMD2_SET) {
 116                                 if (set->cmd2 & CMD2_UBITS)
 117                                         newmode |= (value<<6) & set->bits;
 118                                 if (set->cmd2 & CMD2_GBITS)
 119                                         newmode |= (value<<3) & set->bits;
 120                                 if (set->cmd2 & CMD2_OBITS)
 121                                         newmode |= value & set->bits;
 122                         }
 123                         break;
 124
 125                 case '+':
 126                         newmode |= set->bits;
 127                         break;
 128
 129                 case '-':
 130                         newmode &= ~set->bits;
 131                         break;
 132
 133                 case 'X':
 134                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 135                                 newmode |= set->bits;
 136                         break;
 137
 138                 case '\0':
 139                 default:
 140 #ifdef SETMODE_DEBUG
 141                         printf("getmode:%04o -> %04o\n", omode, newmode);
 142 #endif
 143                         return (newmode);
 144                 }
 145 }
 146
 147 #define ADDCMD(a, b, c, d)                                              \
 148         if (set >= endset) {                                            \
 149                 BITCMD *newset;                                         \
 150                 setlen += SET_LEN_INCR;                                 \
 151                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 152                 if (!newset) {                                          \
 153                         if (saveset)                                    \
 154                                 free(saveset);                          \
 155                         saveset = NULL;                                 \
 156                         return (NULL);                                  \
 157                 }                                                       \
 158                 set = newset + (set - saveset);                         \
 159                 saveset = newset;                                       \
 160                 endset = newset + (setlen - 2);                         \
 161         }                                                               \
 162         set = addcmd(set, (a), (b), (c), (d))
 163
 164 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 165
 166 void *
 167 setmode(const char *p)
 168 {
 169         int perm, who;
 170         char op, *ep;
 171         BITCMD *set, *saveset, *endset;
 172         sigset_t sigset, sigoset;
 173         mode_t mask;
 174         int equalopdone=0, permXbits, setlen;
 175         long perml;
 176
 177         if (!*p)
 178                 return (NULL);
 179
 180         /*
 181          * Get a copy of the mask for the permissions that are mask relative.
 182          * Flip the bits, we want what's not set.  Since it's possible that
 183          * the caller is opening files inside a signal handler, protect them
 184          * as best we can.
 185          */
 186         sigfillset(&sigset);
 187         _sigprocmask(SIG_BLOCK, &sigset, &sigoset);
 188         umask(mask = umask(0));
 189         mask = ~mask;
 190         _sigprocmask(SIG_SETMASK, &sigoset, NULL);
 191
 192         setlen = SET_LEN + 2;
 193
 194         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 195                 return (NULL);
 196         saveset = set;
 197         endset = set + (setlen - 2);
 198
 199         /*
 200          * If an absolute number, get it and return; disallow non-octal digits
 201          * or illegal bits.
 202          */
 203         if (isdigit((unsigned char)*p)) {
 204                 perml = strtol(p, &ep, 8);
 205                 if (*ep || perml < 0 || perml & ~(STANDARD_BITS|S_ISTXT)) {
 206                         free(saveset);
 207                         return (NULL);
 208                 }
 209                 perm = (mode_t)perml;
 210                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 211                 set->cmd = 0;
 212                 return (saveset);
 213         }
 214
 215         /*
 216          * Build list of structures to set/clear/copy bits as described by
 217          * each clause of the symbolic mode.
 218          */
 219         for (;;) {
 220                 /* First, find out which bits might be modified. */
 221                 for (who = 0;; ++p) {
 222                         switch (*p) {
 223                         case 'a':
 224                                 who |= STANDARD_BITS;
 225                                 break;
 226                         case 'u':
 227                                 who |= S_ISUID|S_IRWXU;
 228                                 break;
 229                         case 'g':
 230                                 who |= S_ISGID|S_IRWXG;
 231                                 break;
 232                         case 'o':
 233                                 who |= S_IRWXO;
 234                                 break;
 235                         default:
 236                                 goto getop;
 237                         }
 238                 }
 239
 240 getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
 241                         free(saveset);
 242                         return (NULL);
 243                 }
 244                 if (op == '=')
 245                         equalopdone = 0;
 246
 247                 who &= ~S_ISTXT;
 248                 for (perm = 0, permXbits = 0;; ++p) {
 249                         switch (*p) {
 250                         case 'r':
 251                                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
 252                                 break;
 253                         case 's':
 254                                 /* If only "other" bits ignore set-id. */
 255                                 if (!who || who & ~S_IRWXO)
 256                                         perm |= S_ISUID|S_ISGID;
 257                                 break;
 258                         case 't':
 259                                 /* If only "other" bits ignore sticky. */
 260                                 if (!who || who & ~S_IRWXO) {
 261                                         who |= S_ISTXT;
 262                                         perm |= S_ISTXT;
 263                                 }
 264                                 break;
 265                         case 'w':
 266                                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
 267                                 break;
 268                         case 'X':
 269                                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
 270                                 break;
 271                         case 'x':
 272                                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
 273                                 break;
 274                         case 'u':
 275                         case 'g':
 276                         case 'o':
 277                                 /*
 278                                  * When ever we hit 'u', 'g', or 'o', we have
 279                                  * to flush out any partial mode that we have,
 280                                  * and then do the copying of the mode bits.
 281                                  */
 282                                 if (perm) {
 283                                         ADDCMD(op, who, perm, mask);
 284                                         perm = 0;
 285                                 }
 286                                 if (op == '=')
 287                                         equalopdone = 1;
 288                                 if (op == '+' && permXbits) {
 289                                         ADDCMD('X', who, permXbits, mask);
 290                                         permXbits = 0;
 291                                 }
 292                                 ADDCMD(*p, who, op, mask);
 293                                 break;
 294
 295                         default:
 296                                 /*
 297                                  * Add any permissions that we haven't already
 298                                  * done.
 299                                  */
 300                                 if (perm || (op == '=' && !equalopdone)) {
 301                                         if (op == '=')
 302                                                 equalopdone = 1;
 303                                         ADDCMD(op, who, perm, mask);
 304                                         perm = 0;
 305                                 }
 306                                 if (permXbits) {
 307                                         ADDCMD('X', who, permXbits, mask);
 308                                         permXbits = 0;
 309                                 }
 310                                 goto apply;
 311                         }
 312                 }
 313
 314 apply:          if (!*p)
 315                         break;
 316                 if (*p != ',')
 317                         goto getop;
 318                 ++p;
 319         }
 320         set->cmd = 0;
 321 #ifdef SETMODE_DEBUG
 322         printf("Before compress_mode()\n");
 323         dumpmode(saveset);
 324 #endif
 325         compress_mode(saveset);
 326 #ifdef SETMODE_DEBUG
 327         printf("After compress_mode()\n");
 328         dumpmode(saveset);
 329 #endif
 330         return (saveset);
 331 }
 332
 333 static BITCMD *
 334 addcmd(BITCMD *set, int op, int who, int oparg, u_int mask)
 335 {
 336         switch (op) {
 337         case '=':
 338                 set->cmd = '-';
 339                 set->bits = who ? who : STANDARD_BITS;
 340                 set++;
 341
 342                 op = '+';
 343                 /* FALLTHROUGH */
 344         case '+':
 345         case '-':
 346         case 'X':
 347                 set->cmd = op;
 348                 set->bits = (who ? who : mask) & oparg;
 349                 break;
 350
 351         case 'u':
 352         case 'g':
 353         case 'o':
 354                 set->cmd = op;
 355                 if (who) {
 356                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 357                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 358                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 359                         set->bits = (mode_t)~0;
 360                 } else {
 361                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 362                         set->bits = mask;
 363                 }
 364
 365                 if (oparg == '+')
 366                         set->cmd2 |= CMD2_SET;
 367                 else if (oparg == '-')
 368                         set->cmd2 |= CMD2_CLR;
 369                 else if (oparg == '=')
 370                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 371                 break;
 372         }
 373         return (set + 1);
 374 }
 375
 376 #ifdef SETMODE_DEBUG
 377 static void
 378 dumpmode(BITCMD *set)
 379 {
 380         for (; set->cmd; ++set)
 381                 printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 382                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 383                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 384                     set->cmd2 & CMD2_SET ? " SET" : "",
 385                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 386                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 387                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 388 }
 389 #endif
 390
 391 /*
 392  * Given an array of bitcmd structures, compress by compacting consecutive
 393  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 394  * 'g' and 'o' commands continue to be separate.  They could probably be
 395  * compacted, but it's not worth the effort.
 396  */
 397 static void
 398 compress_mode(BITCMD *set)
 399 {
 400         BITCMD *nset;
 401         int setbits, clrbits, Xbits, op;
 402
 403         for (nset = set;;) {
 404                 /* Copy over any 'u', 'g' and 'o' commands. */
 405                 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
 406                         *set++ = *nset++;
 407                         if (!op)
 408                                 return;
 409                 }
 410
 411                 for (setbits = clrbits = Xbits = 0;; nset++) {
 412                         if ((op = nset->cmd) == '-') {
 413                                 clrbits |= nset->bits;
 414                                 setbits &= ~nset->bits;
 415                                 Xbits &= ~nset->bits;
 416                         } else if (op == '+') {
 417                                 setbits |= nset->bits;
 418                                 clrbits &= ~nset->bits;
 419                                 Xbits &= ~nset->bits;
 420                         } else if (op == 'X')
 421                                 Xbits |= nset->bits & ~setbits;
 422                         else
 423                                 break;
 424                 }
 425                 if (clrbits) {
 426                         set->cmd = '-';
 427                         set->cmd2 = 0;
 428                         set->bits = clrbits;
 429                         set++;
 430                 }
 431                 if (setbits) {
 432                         set->cmd = '+';
 433                         set->cmd2 = 0;
 434                         set->bits = setbits;
 435                         set++;
 436                 }
 437                 if (Xbits) {
 438                         set->cmd = 'X';
 439                         set->cmd2 = 0;
 440                         set->bits = Xbits;
 441                         set++;
 442                 }
 443         }
 444 }