usr/src/lib/libc/port/gen/setmode.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   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/types.h>
  36 #include <sys/stat.h>
  37
  38 #include <ctype.h>
  39 #include <errno.h>
  40 #include <limits.h>
  41 #include <signal.h>
  42 #include <stddef.h>
  43 #include <stdlib.h>
  44 #include <unistd.h>
  45
  46 #ifdef SETMODE_DEBUG
  47 #include <stdio.h>
  48 #endif
  49
  50 #include "thr_uberdata.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 mode_t    getumask(void);
  68 static BITCMD   *addcmd(BITCMD *, mode_t, mode_t, mode_t, mode_t);
  69 static void      compress_mode(BITCMD *);
  70 #ifdef SETMODE_DEBUG
  71 static void      dumpmode(BITCMD *);
  72 #endif
  73
  74 /*
  75  * Given the old mode and an array of bitcmd structures, apply the operations
  76  * described in the bitcmd structures to the old mode, and return the new mode.
  77  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  78  * bits) followed by a '+' (set bits).
  79  */
  80 mode_t
  81 getmode(const void *bbox, mode_t omode)
  82 {
  83         const BITCMD *set;
  84         mode_t clrval, newmode, value;
  85
  86         set = (const BITCMD *)bbox;
  87         newmode = omode;
  88         for (value = 0;; set++)
  89                 switch(set->cmd) {
  90                 /*
  91                  * When copying the user, group or other bits around, we "know"
  92                  * where the bits are in the mode so that we can do shifts to
  93                  * copy them around.  If we don't use shifts, it gets real
  94                  * grundgy with lots of single bit checks and bit sets.
  95                  */
  96                 case 'u':
  97                         value = (newmode & S_IRWXU) >> 6;
  98                         goto common;
  99
 100                 case 'g':
 101                         value = (newmode & S_IRWXG) >> 3;
 102                         goto common;
 103
 104                 case 'o':
 105                         value = newmode & S_IRWXO;
 106 common:                 if (set->cmd2 & CMD2_CLR) {
 107                                 clrval =
 108                                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
 109                                 if (set->cmd2 & CMD2_UBITS)
 110                                         newmode &= ~((clrval<<6) & set->bits);
 111                                 if (set->cmd2 & CMD2_GBITS)
 112                                         newmode &= ~((clrval<<3) & set->bits);
 113                                 if (set->cmd2 & CMD2_OBITS)
 114                                         newmode &= ~(clrval & set->bits);
 115                         }
 116                         if (set->cmd2 & CMD2_SET) {
 117                                 if (set->cmd2 & CMD2_UBITS)
 118                                         newmode |= (value<<6) & set->bits;
 119                                 if (set->cmd2 & CMD2_GBITS)
 120                                         newmode |= (value<<3) & set->bits;
 121                                 if (set->cmd2 & CMD2_OBITS)
 122                                         newmode |= value & set->bits;
 123                         }
 124                         break;
 125
 126                 case '+':
 127                         newmode |= set->bits;
 128                         break;
 129
 130                 case '-':
 131                         newmode &= ~set->bits;
 132                         break;
 133
 134                 case 'X':
 135                         if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
 136                                 newmode |= set->bits;
 137                         break;
 138
 139                 case '\0':
 140                 default:
 141 #ifdef SETMODE_DEBUG
 142                         (void)printf("getmode:%04o -> %04o\n", omode, newmode);
 143 #endif
 144                         return (newmode);
 145                 }
 146 }
 147
 148 #define ADDCMD(a, b, c, d)                                              \
 149         if (set >= endset) {                                            \
 150                 BITCMD *newset;                                         \
 151                 setlen += SET_LEN_INCR;                                 \
 152                 newset = reallocarray(saveset, setlen, sizeof(BITCMD)); \
 153                 if (newset == NULL)                                     \
 154                         goto out;                                       \
 155                 set = newset + (set - saveset);                         \
 156                 saveset = newset;                                       \
 157                 endset = newset + (setlen - 2);                         \
 158         }                                                               \
 159         set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d))
 160
 161 #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
 162
 163 void *
 164 setmode(const char *p)
 165 {
 166         int serrno;
 167         char op, *ep;
 168         BITCMD *set, *saveset, *endset;
 169         mode_t mask, perm, permXbits, who;
 170         long perml;
 171         int equalopdone;
 172         u_int setlen;
 173
 174         if (!*p) {
 175                 errno = EINVAL;
 176                 return (NULL);
 177         }
 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.
 182          */
 183         mask = ~getumask();
 184
 185         setlen = SET_LEN + 2;
 186
 187         if ((set = malloc(setlen * sizeof(BITCMD))) == NULL)
 188                 return (NULL);
 189         saveset = set;
 190         endset = set + (setlen - 2);
 191
 192         /*
 193          * If an absolute number, get it and return; disallow non-octal digits
 194          * or illegal bits.
 195          */
 196         if (isdigit((unsigned char)*p)) {
 197                 errno = 0;
 198                 perml = strtol(p, &ep, 8);
 199                 if (*ep) {
 200                         errno = EINVAL;
 201                         goto out;
 202                 }
 203                 if (errno == ERANGE && (perml == LONG_MAX || perml == LONG_MIN))
 204                         goto out;
 205                 if (perml & ~(STANDARD_BITS|S_ISVTX)) {
 206                         errno = EINVAL;
 207                         goto out;
 208                 }
 209                 perm = (mode_t)perml;
 210                 ADDCMD('=', (STANDARD_BITS|S_ISVTX), 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         equalopdone = 0;
 220         for (;;) {
 221                 /* First, find out which bits might be modified. */
 222                 for (who = 0;; ++p) {
 223                         switch (*p) {
 224                         case 'a':
 225                                 who |= STANDARD_BITS;
 226                                 break;
 227                         case 'u':
 228                                 who |= S_ISUID|S_IRWXU;
 229                                 break;
 230                         case 'g':
 231                                 who |= S_ISGID|S_IRWXG;
 232                                 break;
 233                         case 'o':
 234                                 who |= S_IRWXO;
 235                                 break;
 236                         default:
 237                                 goto getop;
 238                         }
 239                 }
 240
 241 getop:          if ((op = *p++) != '+' && op != '-' && op != '=') {
 242                         errno = EINVAL;
 243                         goto out;
 244                 }
 245                 if (op == '=')
 246                         equalopdone = 0;
 247
 248                 who &= ~S_ISVTX;
 249                 for (perm = 0, permXbits = 0;; ++p) {
 250                         switch (*p) {
 251                         case 'r':
 252                                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
 253                                 break;
 254                         case 's':
 255                                 /* If only "other" bits ignore set-id. */
 256                                 if (!who || who & ~S_IRWXO)
 257                                         perm |= S_ISUID|S_ISGID;
 258                                 break;
 259                         case 't':
 260                                 /* If only "other" bits ignore sticky. */
 261                                 if (!who || who & ~S_IRWXO) {
 262                                         who |= S_ISVTX;
 263                                         perm |= S_ISVTX;
 264                                 }
 265                                 break;
 266                         case 'w':
 267                                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
 268                                 break;
 269                         case 'X':
 270                                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
 271                                 break;
 272                         case 'x':
 273                                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
 274                                 break;
 275                         case 'u':
 276                         case 'g':
 277                         case 'o':
 278                                 /*
 279                                  * When ever we hit 'u', 'g', or 'o', we have
 280                                  * to flush out any partial mode that we have,
 281                                  * and then do the copying of the mode bits.
 282                                  */
 283                                 if (perm) {
 284                                         ADDCMD(op, who, perm, mask);
 285                                         perm = 0;
 286                                 }
 287                                 if (op == '=')
 288                                         equalopdone = 1;
 289                                 if (op == '+' && permXbits) {
 290                                         ADDCMD('X', who, permXbits, mask);
 291                                         permXbits = 0;
 292                                 }
 293                                 ADDCMD(*p, who, op, mask);
 294                                 break;
 295
 296                         default:
 297                                 /*
 298                                  * Add any permissions that we haven't already
 299                                  * done.
 300                                  */
 301                                 if (perm || (op == '=' && !equalopdone)) {
 302                                         if (op == '=')
 303                                                 equalopdone = 1;
 304                                         ADDCMD(op, who, perm, mask);
 305                                         perm = 0;
 306                                 }
 307                                 if (permXbits) {
 308                                         ADDCMD('X', who, permXbits, mask);
 309                                         permXbits = 0;
 310                                 }
 311                                 goto apply;
 312                         }
 313                 }
 314
 315 apply:          if (!*p)
 316                         break;
 317                 if (*p != ',')
 318                         goto getop;
 319                 ++p;
 320         }
 321         set->cmd = 0;
 322 #ifdef SETMODE_DEBUG
 323         (void)printf("Before compress_mode()\n");
 324         dumpmode(saveset);
 325 #endif
 326         compress_mode(saveset);
 327 #ifdef SETMODE_DEBUG
 328         (void)printf("After compress_mode()\n");
 329         dumpmode(saveset);
 330 #endif
 331         return (saveset);
 332 out:
 333         serrno = errno;
 334         free(saveset);
 335         errno = serrno;
 336         return NULL;
 337 }
 338
 339 static mode_t
 340 getumask(void)
 341 {
 342         sigset_t sigset, sigoset;
 343         size_t len;
 344         mode_t mask;
 345         u_short smask;
 346
 347         /*
 348          * Since it's possible that the caller is opening files inside a signal
 349          * handler, protect them as best we can.
 350          */
 351         sigfillset(&sigset);
 352         (void)__sigprocmask(SIG_BLOCK, &sigset, &sigoset);
 353         (void)umask(mask = umask(0));
 354         (void)__sigprocmask(SIG_SETMASK, &sigoset, NULL);
 355         return (mask);
 356 }
 357
 358 static BITCMD *
 359 addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
 360 {
 361         switch (op) {
 362         case '=':
 363                 set->cmd = '-';
 364                 set->bits = who ? who : STANDARD_BITS;
 365                 set++;
 366
 367                 op = '+';
 368                 /* FALLTHROUGH */
 369         case '+':
 370         case '-':
 371         case 'X':
 372                 set->cmd = op;
 373                 set->bits = (who ? who : mask) & oparg;
 374                 break;
 375
 376         case 'u':
 377         case 'g':
 378         case 'o':
 379                 set->cmd = op;
 380                 if (who) {
 381                         set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
 382                                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
 383                                     ((who & S_IROTH) ? CMD2_OBITS : 0);
 384                         set->bits = (mode_t)~0;
 385                 } else {
 386                         set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
 387                         set->bits = mask;
 388                 }
 389
 390                 if (oparg == '+')
 391                         set->cmd2 |= CMD2_SET;
 392                 else if (oparg == '-')
 393                         set->cmd2 |= CMD2_CLR;
 394                 else if (oparg == '=')
 395                         set->cmd2 |= CMD2_SET|CMD2_CLR;
 396                 break;
 397         }
 398         return (set + 1);
 399 }
 400
 401 #ifdef SETMODE_DEBUG
 402 static void
 403 dumpmode(BITCMD *set)
 404 {
 405         for (; set->cmd; ++set)
 406                 (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
 407                     set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
 408                     set->cmd2 & CMD2_CLR ? " CLR" : "",
 409                     set->cmd2 & CMD2_SET ? " SET" : "",
 410                     set->cmd2 & CMD2_UBITS ? " UBITS" : "",
 411                     set->cmd2 & CMD2_GBITS ? " GBITS" : "",
 412                     set->cmd2 & CMD2_OBITS ? " OBITS" : "");
 413 }
 414 #endif
 415
 416 /*
 417  * Given an array of bitcmd structures, compress by compacting consecutive
 418  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
 419  * 'g' and 'o' commands continue to be separate.  They could probably be
 420  * compacted, but it's not worth the effort.
 421  */
 422 static void
 423 compress_mode(BITCMD *set)
 424 {
 425         BITCMD *nset;
 426         int setbits, clrbits, Xbits, op;
 427
 428         for (nset = set;;) {
 429                 /* Copy over any 'u', 'g' and 'o' commands. */
 430                 while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
 431                         *set++ = *nset++;
 432                         if (!op)
 433                                 return;
 434                 }
 435
 436                 for (setbits = clrbits = Xbits = 0;; nset++) {
 437                         if ((op = nset->cmd) == '-') {
 438                                 clrbits |= nset->bits;
 439                                 setbits &= ~nset->bits;
 440                                 Xbits &= ~nset->bits;
 441                         } else if (op == '+') {
 442                                 setbits |= nset->bits;
 443                                 clrbits &= ~nset->bits;
 444                                 Xbits &= ~nset->bits;
 445                         } else if (op == 'X')
 446                                 Xbits |= nset->bits & ~setbits;
 447                         else
 448                                 break;
 449                 }
 450                 if (clrbits) {
 451                         set->cmd = '-';
 452                         set->cmd2 = 0;
 453                         set->bits = clrbits;
 454                         set++;
 455                 }
 456                 if (setbits) {
 457                         set->cmd = '+';
 458                         set->cmd2 = 0;
 459                         set->bits = setbits;
 460                         set++;
 461                 }
 462                 if (Xbits) {
 463                         set->cmd = 'X';
 464                         set->cmd2 = 0;
 465                         set->bits = Xbits;
 466                         set++;
 467                 }
 468         }
 469 }