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
  37 #if defined(LIBC_SCCS) && !defined(lint)
  38 #if 0
  39 static char sccsid[] = "@(#)setmode.c   8.2 (Berkeley) 3/25/94";
  40 #endif
  41 static const char rcsid[] =
  42   "$FreeBSD: src/lib/libc/gen/setmode.c,v 1.5.2.1 2001/03/05 09:34:10 obrien Exp $";
  43 #endif /* LIBC_SCCS and not lint */
  44
  45 #include <sys/types.h>
  46 #include <sys/stat.h>
  47
  48 #include <ctype.h>
  49 #include <signal.h>
  50 #include <stddef.h>
  51 #include <stdlib.h>
  52
  53 #ifdef SETMODE_DEBUG
  54 #include <stdio.h>
  55 #endif
  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 BITCMD   *addcmd __P((BITCMD *, int, int, int, u_int));
  73 static void      compress_mode __P((BITCMD *));
  74 #ifdef SETMODE_DEBUG
  75 static void      dumpmode __P((BITCMD *));
  76 #endif
  77
  78 /*
  79  * Given the old mode and an array of bitcmd structures, apply the operations
  80  * described in the bitcmd structures to the old mode, and return the new mode.
  81  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  82  * bits) followed by a '+' (set bits).
  83  */
  84 mode_t
  85 getmode(bbox, omode)
  86         void *bbox;
  87         mode_t omode;
  88 {
  89         register BITCMD *set;
  90         register mode_t clrval, newmode, value;
  91
  92         set = (BITCMD *)bbox;
  93         newmode = omode;
  94         for (value = 0;; set++)
  95                 switch(set->cmd) {
  96                 /*
  97                  * When copying the user, group or other bits around, we "know"
  98                  * where the bits are in the mode so that we can do shifts to
  99                  * copy them around.  If we don't use shifts, it gets real
 100                  * grundgy with lots of single bit checks and bit sets.
 101                  */
 102                 case 'u':
 103                         value = (newmode & S_IRWXU) >> 6;
 104                         goto common;
 105
 106                 case 'g':
 107                         value = (newmode & S_IRWXG) >> 3;
 108                         goto common;
 109
 110                 case 'o':
 111                         value = newmode & S_IRWXO;
 112 common:                 if (set->cmd2 & CMD2_CLR) {
 113                                 clrval =
 114                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 115                                 if (set->cmd2 & CMD2_UBITS)
 116                                         newmode &= ~((clrval<<6) & set->bits);
 117                                 if (set->cmd2 & CMD2_GBITS)
 118                                         newmode &= ~((clrval<<3) & set->bits);
 119                                 if (set->cmd2 & CMD2_OBITS)
 120                                         newmode &= ~(clrval & set->bits);
 121                         }
 122                         if (set->cmd2 & CMD2_SET) {
 123                                 if (set->cmd2 & CMD2_UBITS)
 124                                         newmode |= (value<<6) & set->bits;
 125                                 if (set->cmd2 & CMD2_GBITS)
 126                                         newmode |= (value<<3) & set->bits;
 127                                 if (set->cmd2 & CMD2_OBITS)
 128                                         newmode |= value & set->bits;
 129                         }
 130                         break;
 131
 132                 case '+':
 133                         newmode |= set->bits;
 134                         break;
 135
 136                 case '-':
 137                         newmode &= ~set->bits;
 138                         break;
 139
 140                 case 'X':
 141                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 142                                 newmode |= set->bits;
 143                         break;
 144
 145                 case '\0':
 146                 default:
 147 #ifdef SETMODE_DEBUG
 148                         (void)printf("getmode:%04o -> %04o\n", omode, newmode);
 149 #endif
 150                         return (newmode);
 151                 }
 152 }
 153
 154 #define ADDCMD(a, b, c, d)                                              \
 155         if (set >= endset) {                                            \
 156                 register BITCMD *newset;                                \
 157                 setlen += SET_LEN_INCR;                                 \
 158                 newset = realloc(saveset, sizeof(BITCMD) * setlen);     \
 159                 if (!saveset)                                           \
 160                         return (NULL);                                  \
 161                 set = newset + (set - saveset);                         \
 162                 saveset = newset;                                       \
 163                 endset = newset + (setlen - 2);                         \
 164         }                                                               \
 165         set = addcmd(set, (a), (b), (c), (d))
 166
 167 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 168
 169 void *
 170 setmode(p)
 171         register char *p;
 172 {
 173         register int perm, who;
 174         register char op;
 175         BITCMD *set, *saveset, *endset;
 176         sigset_t sigset, sigoset;
 177         mode_t mask;
 178         int equalopdone=0, permXbits, setlen;
 179
 180         if (!*p)
 181                 return (NULL);
 182
 183         /*
 184          * Get a copy of the mask for the permissions that are mask relative.
 185          * Flip the bits, we want what's not set.  Since it's possible that
 186          * the caller is opening files inside a signal handler, protect them
 187          * as best we can.
 188          */
 189         sigfillset(&sigset);
 190         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
 191         (void)umask(mask = umask(0));
 192         mask = ~mask;
 193         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
 194
 195         setlen = SET_LEN + 2;
 196
 197         if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
 198                 return (NULL);
 199         saveset = set;
 200         endset = set + (setlen - 2);
 201
 202         /*
 203          * If an absolute number, get it and return; disallow non-octal digits
 204          * or illegal bits.
 205          */
 206         if (isdigit((unsigned char)*p)) {
 207                 perm = (mode_t)strtol(p, NULL, 8);
 208                 if (perm & ~(STANDARD_BITS|S_ISTXT)) {
 209                         free(saveset);
 210                         return (NULL);
 211                 }
 212                 while (*++p)
 213                         if (*p < '0' || *p > '7') {
 214                                 free(saveset);
 215                                 return (NULL);
 216                         }
 217                 ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
 218                 return (saveset);
 219         }
 220
 221         /*
 222          * Build list of structures to set/clear/copy bits as described by
 223          * each clause of the symbolic mode.
 224          */
 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                         free(saveset);
 248                         return (NULL);
 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 }
 338
 339 static BITCMD *
 340 addcmd(set, op, who, oparg, mask)
 341         BITCMD *set;
 342         register int oparg, who;
 343         register int op;
 344         u_int mask;
 345 {
 346         switch (op) {
 347         case '=':
 348                 set->cmd = '-';
 349                 set->bits = who ? who : STANDARD_BITS;
 350                 set++;
 351
 352                 op = '+';
 353                 /* FALLTHROUGH */
 354         case '+':
 355         case '-':
 356         case 'X':
 357                 set->cmd = op;
 358                 set->bits = (who ? who : mask) & oparg;
 359                 break;
 360
 361         case 'u':
 362         case 'g':
 363         case 'o':
 364                 set->cmd = op;
 365                 if (who) {
 366                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 367                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 368                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 369                         set->bits = ~0;
 370                 } else {
 371                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 372                         set->bits = mask;
 373                 }
 374
 375                 if (oparg == '+')
 376                         set->cmd2 |= CMD2_SET;
 377                 else if (oparg == '-')
 378                         set->cmd2 |= CMD2_CLR;
 379                 else if (oparg == '=')
 380                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 381                 break;
 382         }
 383         return (set + 1);
 384 }
 385
 386 #ifdef SETMODE_DEBUG
 387 static void
 388 dumpmode(set)
 389         register BITCMD *set;
 390 {
 391         for (; set->cmd; ++set)
 392                 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 393                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 394                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 395                     set->cmd2 & CMD2_SET ? " SET" : "",
 396                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 397                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 398                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 399 }
 400 #endif
 401
 402 /*
 403  * Given an array of bitcmd structures, compress by compacting consecutive
 404  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 405  * 'g' and 'o' commands continue to be separate.  They could probably be
 406  * compacted, but it's not worth the effort.
 407  */
 408 static void
 409 compress_mode(set)
 410         register BITCMD *set;
 411 {
 412         register BITCMD *nset;
 413         register int setbits, clrbits, Xbits, op;
 414
 415         for (nset = set;;) {
 416                 /* Copy over any 'u', 'g' and 'o' commands. */
 417                 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
 418                         *set++ = *nset++;
 419                         if (!op)
 420                                 return;
 421                 }
 422
 423                 for (setbits = clrbits = Xbits = 0;; nset++) {
 424                         if ((op = nset->cmd) == '-') {
 425                                 clrbits |= nset->bits;
 426                                 setbits &= ~nset->bits;
 427                                 Xbits &= ~nset->bits;
 428                         } else if (op == '+') {
 429                                 setbits |= nset->bits;
 430                                 clrbits &= ~nset->bits;
 431                                 Xbits &= ~nset->bits;
 432                         } else if (op == 'X')
 433                                 Xbits |= nset->bits & ~setbits;
 434                         else
 435                                 break;
 436                 }
 437                 if (clrbits) {
 438                         set->cmd = '-';
 439                         set->cmd2 = 0;
 440                         set->bits = clrbits;
 441                         set++;
 442                 }
 443                 if (setbits) {
 444                         set->cmd = '+';
 445                         set->cmd2 = 0;
 446                         set->bits = setbits;
 447                         set++;
 448                 }
 449                 if (Xbits) {
 450                         set->cmd = 'X';
 451                         set->cmd2 = 0;
 452                         set->bits = Xbits;
 453                         set++;
 454                 }
 455         }
 456 }