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  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)setmode.c        8.2 (Berkeley) 3/25/94
  37  * $FreeBSD: src/lib/libc/gen/setmode.c,v 1.5.2.1 2001/03/05 09:34:10 obrien Exp $
  38  * $DragonFly: src/lib/libc/gen/setmode.c,v 1.7 2005/11/19 22:32:53 swildner Exp $
  39  */
  40
  41 #include "namespace.h"
  42 #include <sys/types.h>
  43 #include <sys/stat.h>
  44
  45 #include <ctype.h>
  46 #include <signal.h>
  47 #include <stddef.h>
  48 #include <stdlib.h>
  49 #include <unistd.h>
  50
  51 #ifdef SETMODE_DEBUG
  52 #include <stdio.h>
  53 #endif
  54 #include "un-namespace.h"
  55
  56 #define SET_LEN 6               /* initial # of bitcmd struct to malloc */
  57 #define SET_LEN_INCR 4          /* # of bitcmd structs to add as needed */
  58
  59 typedef struct bitcmd {
  60         char    cmd;
  61         char    cmd2;
  62         mode_t  bits;
  63 } BITCMD;
  64
  65 #define CMD2_CLR        0x01
  66 #define CMD2_SET        0x02
  67 #define CMD2_GBITS      0x04
  68 #define CMD2_OBITS      0x08
  69 #define CMD2_UBITS      0x10
  70
  71 static BITCMD   *addcmd (BITCMD *, int, int, int, u_int);
  72 static void      compress_mode (BITCMD *);
  73 #ifdef SETMODE_DEBUG
  74 static void      dumpmode (BITCMD *);
  75 #endif
  76
  77 /*
  78  * Given the old mode and an array of bitcmd structures, apply the operations
  79  * described in the bitcmd structures to the old mode, and return the new mode.
  80  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  81  * bits) followed by a '+' (set bits).
  82  */
  83 mode_t
  84 getmode(const void *bbox, mode_t omode)
  85 {
  86         BITCMD *set;
  87         mode_t clrval, newmode, value;
  88
  89         set = (BITCMD *)bbox;
  90         newmode = omode;
  91         for (value = 0;; set++)
  92                 switch(set->cmd) {
  93                 /*
  94                  * When copying the user, group or other bits around, we "know"
  95                  * where the bits are in the mode so that we can do shifts to
  96                  * copy them around.  If we don't use shifts, it gets real
  97                  * grundgy with lots of single bit checks and bit sets.
  98                  */
  99                 case 'u':
 100                         value = (newmode & S_IRWXU) >> 6;
 101                         goto common;
 102
 103                 case 'g':
 104                         value = (newmode & S_IRWXG) >> 3;
 105                         goto common;
 106
 107                 case 'o':
 108                         value = newmode & S_IRWXO;
 109 common:                 if (set->cmd2 & CMD2_CLR) {
 110                                 clrval =
 111                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 112                                 if (set->cmd2 & CMD2_UBITS)
 113                                         newmode &= ~((clrval<<6) & set->bits);
 114                                 if (set->cmd2 & CMD2_GBITS)
 115                                         newmode &= ~((clrval<<3) & set->bits);
 116                                 if (set->cmd2 & CMD2_OBITS)
 117                                         newmode &= ~(clrval & set->bits);
 118                         }
 119                         if (set->cmd2 & CMD2_SET) {
 120                                 if (set->cmd2 & CMD2_UBITS)
 121                                         newmode |= (value<<6) & set->bits;
 122                                 if (set->cmd2 & CMD2_GBITS)
 123                                         newmode |= (value<<3) & set->bits;
 124                                 if (set->cmd2 & CMD2_OBITS)
 125                                         newmode |= value & set->bits;
 126                         }
 127                         break;
 128
 129                 case '+':
 130                         newmode |= set->bits;
 131                         break;
 132
 133                 case '-':
 134                         newmode &= ~set->bits;
 135                         break;
 136
 137                 case 'X':
 138                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 139                                 newmode |= set->bits;
 140                         break;
 141
 142                 case '\0':
 143                 default:
 144 #ifdef SETMODE_DEBUG
 145                         printf("getmode:%04o -> %04o\n", omode, newmode);
 146 #endif
 147                         return (newmode);
 148                 }
 149 }
 150
 151 #define ADDCMD(a, b, c, d)                                              \
 152         if (set >= endset) {                                            \
 153                 BITCMD *newset;                         \
 154                 setlen += SET_LEN_INCR;                                 \
 155                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 156                 if (!saveset)                                           \
 157                         return (NULL);                                  \
 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;
 171         BITCMD *set, *saveset, *endset;
 172         sigset_t sigset, sigoset;
 173         mode_t mask;
 174         int equalopdone=0, permXbits, setlen;
 175
 176         if (!*p)
 177                 return (NULL);
 178
 179         /*
 180          * Get a copy of the mask for the permissions that are mask relative.
 181          * Flip the bits, we want what's not set.  Since it's possible that
 182          * the caller is opening files inside a signal handler, protect them
 183          * as best we can.
 184          */
 185         sigfillset(&sigset);
 186         _sigprocmask(SIG_BLOCK, &sigset, &sigoset);
 187         umask(mask = umask(0));
 188         mask = ~mask;
 189         _sigprocmask(SIG_SETMASK, &sigoset, NULL);
 190
 191         setlen = SET_LEN + 2;
 192
 193         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 194                 return (NULL);
 195         saveset = set;
 196         endset = set + (setlen - 2);
 197
 198         /*
 199          * If an absolute number, get it and return; disallow non-octal digits
 200          * or illegal bits.
 201          */
 202         if (isdigit((unsigned char)*p)) {
 203                 perm = (mode_t)strtol(p, NULL, 8);
 204                 if (perm & ~(STANDARD_BITS|S_ISTXT)) {
 205                         free(saveset);
 206                         return (NULL);
 207                 }
 208                 while (*++p)
 209                         if (*p < '0' || *p > '7') {
 210                                 free(saveset);
 211                                 return (NULL);
 212                         }
 213                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 214                 return (saveset);
 215         }
 216
 217         /*
 218          * Build list of structures to set/clear/copy bits as described by
 219          * each clause of the symbolic mode.
 220          */
 221         for (;;) {
 222                 /* First, find out which bits might be modified. */
 223                 for (who = 0;; ++p) {
 224                         switch (*p) {
 225                         case 'a':
 226                                 who |= STANDARD_BITS;
 227                                 break;
 228                         case 'u':
 229                                 who |= S_ISUID|S_IRWXU;
 230                                 break;
 231                         case 'g':
 232                                 who |= S_ISGID|S_IRWXG;
 233                                 break;
 234                         case 'o':
 235                                 who |= S_IRWXO;
 236                                 break;
 237                         default:
 238                                 goto getop;
 239                         }
 240                 }
 241
 242 getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
 243                         free(saveset);
 244                         return (NULL);
 245                 }
 246                 if (op == '=')
 247                         equalopdone = 0;
 248
 249                 who &= ~S_ISTXT;
 250                 for (perm = 0, permXbits = 0;; ++p) {
 251                         switch (*p) {
 252                         case 'r':
 253                                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
 254                                 break;
 255                         case 's':
 256                                 /* If only "other" bits ignore set-id. */
 257                                 if (!who || who & ~S_IRWXO)
 258                                         perm |= S_ISUID|S_ISGID;
 259                                 break;
 260                         case 't':
 261                                 /* If only "other" bits ignore sticky. */
 262                                 if (!who || who & ~S_IRWXO) {
 263                                         who |= S_ISTXT;
 264                                         perm |= S_ISTXT;
 265                                 }
 266                                 break;
 267                         case 'w':
 268                                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
 269                                 break;
 270                         case 'X':
 271                                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
 272                                 break;
 273                         case 'x':
 274                                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
 275                                 break;
 276                         case 'u':
 277                         case 'g':
 278                         case 'o':
 279                                 /*
 280                                  * When ever we hit 'u', 'g', or 'o', we have
 281                                  * to flush out any partial mode that we have,
 282                                  * and then do the copying of the mode bits.
 283                                  */
 284                                 if (perm) {
 285                                         ADDCMD(op, who, perm, mask);
 286                                         perm = 0;
 287                                 }
 288                                 if (op == '=')
 289                                         equalopdone = 1;
 290                                 if (op == '+' && permXbits) {
 291                                         ADDCMD('X', who, permXbits, mask);
 292                                         permXbits = 0;
 293                                 }
 294                                 ADDCMD(*p, who, op, mask);
 295                                 break;
 296
 297                         default:
 298                                 /*
 299                                  * Add any permissions that we haven't already
 300                                  * done.
 301                                  */
 302                                 if (perm || (op == '=' && !equalopdone)) {
 303                                         if (op == '=')
 304                                                 equalopdone = 1;
 305                                         ADDCMD(op, who, perm, mask);
 306                                         perm = 0;
 307                                 }
 308                                 if (permXbits) {
 309                                         ADDCMD('X', who, permXbits, mask);
 310                                         permXbits = 0;
 311                                 }
 312                                 goto apply;
 313                         }
 314                 }
 315
 316 apply:          if (!*p)
 317                         break;
 318                 if (*p != ',')
 319                         goto getop;
 320                 ++p;
 321         }
 322         set->cmd = 0;
 323 #ifdef SETMODE_DEBUG
 324         printf("Before compress_mode()\n");
 325         dumpmode(saveset);
 326 #endif
 327         compress_mode(saveset);
 328 #ifdef SETMODE_DEBUG
 329         printf("After compress_mode()\n");
 330         dumpmode(saveset);
 331 #endif
 332         return (saveset);
 333 }
 334
 335 static BITCMD *
 336 addcmd(BITCMD *set, int op, int who, int oparg, u_int mask)
 337 {
 338         switch (op) {
 339         case '=':
 340                 set->cmd = '-';
 341                 set->bits = who ? who : STANDARD_BITS;
 342                 set++;
 343
 344                 op = '+';
 345                 /* FALLTHROUGH */
 346         case '+':
 347         case '-':
 348         case 'X':
 349                 set->cmd = op;
 350                 set->bits = (who ? who : mask) & oparg;
 351                 break;
 352
 353         case 'u':
 354         case 'g':
 355         case 'o':
 356                 set->cmd = op;
 357                 if (who) {
 358                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 359                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 360                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 361                         set->bits = ~0;
 362                 } else {
 363                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 364                         set->bits = mask;
 365                 }
 366
 367                 if (oparg == '+')
 368                         set->cmd2 |= CMD2_SET;
 369                 else if (oparg == '-')
 370                         set->cmd2 |= CMD2_CLR;
 371                 else if (oparg == '=')
 372                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 373                 break;
 374         }
 375         return (set + 1);
 376 }
 377
 378 #ifdef SETMODE_DEBUG
 379 static void
 380 dumpmode(BITCMD *set)
 381 {
 382         for (; set->cmd; ++set)
 383                 printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 384                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 385                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 386                     set->cmd2 & CMD2_SET ? " SET" : "",
 387                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 388                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 389                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 390 }
 391 #endif
 392
 393 /*
 394  * Given an array of bitcmd structures, compress by compacting consecutive
 395  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 396  * 'g' and 'o' commands continue to be separate.  They could probably be
 397  * compacted, but it's not worth the effort.
 398  */
 399 static void
 400 compress_mode(BITCMD *set)
 401 {
 402         BITCMD *nset;
 403         int setbits, clrbits, Xbits, op;
 404
 405         for (nset = set;;) {
 406                 /* Copy over any 'u', 'g' and 'o' commands. */
 407                 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
 408                         *set++ = *nset++;
 409                         if (!op)
 410                                 return;
 411                 }
 412
 413                 for (setbits = clrbits = Xbits = 0;; nset++) {
 414                         if ((op = nset->cmd) == '-') {
 415                                 clrbits |= nset->bits;
 416                                 setbits &= ~nset->bits;
 417                                 Xbits &= ~nset->bits;
 418                         } else if (op == '+') {
 419                                 setbits |= nset->bits;
 420                                 clrbits &= ~nset->bits;
 421                                 Xbits &= ~nset->bits;
 422                         } else if (op == 'X')
 423                                 Xbits |= nset->bits & ~setbits;
 424                         else
 425                                 break;
 426                 }
 427                 if (clrbits) {
 428                         set->cmd = '-';
 429                         set->cmd2 = 0;
 430                         set->bits = clrbits;
 431                         set++;
 432                 }
 433                 if (setbits) {
 434                         set->cmd = '+';
 435                         set->cmd2 = 0;
 436                         set->bits = setbits;
 437                         set++;
 438                 }
 439                 if (Xbits) {
 440                         set->cmd = 'X';
 441                         set->cmd2 = 0;
 442                         set->bits = Xbits;
 443                         set++;
 444                 }
 445         }
 446 }