Home | History | Annotate | Line # | Download | only in gen
setmode.c revision 1.25 
      1 /*	$NetBSD: setmode.c,v 1.25 2000/01/20 03:15:04 enami 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. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 #include <sys/cdefs.h>
     40 #if defined(LIBC_SCCS) && !defined(lint)
     41 #if 0
     42 static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
     43 #else
     44 __RCSID("$NetBSD: setmode.c,v 1.25 2000/01/20 03:15:04 enami Exp $");
     45 #endif
     46 #endif /* LIBC_SCCS and not lint */
     47 
     48 #include "namespace.h"
     49 #include <sys/types.h>
     50 #include <sys/stat.h>
     51 
     52 #include <assert.h>
     53 #include <ctype.h>
     54 #include <errno.h>
     55 #include <signal.h>
     56 #include <stdlib.h>
     57 #include <unistd.h>
     58 
     59 #ifdef SETMODE_DEBUG
     60 #include <stdio.h>
     61 #endif
     62 
     63 #ifdef __weak_alias
     64 __weak_alias(getmode,_getmode);
     65 __weak_alias(setmode,_setmode);
     66 #endif
     67 
     68 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     69 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     70 
     71 typedef struct bitcmd {
     72 	char	cmd;
     73 	char	cmd2;
     74 	mode_t	bits;
     75 } BITCMD;
     76 
     77 #define	CMD2_CLR	0x01
     78 #define	CMD2_SET	0x02
     79 #define	CMD2_GBITS	0x04
     80 #define	CMD2_OBITS	0x08
     81 #define	CMD2_UBITS	0x10
     82 
     83 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     84 static void	 compress_mode __P((BITCMD *));
     85 #ifdef SETMODE_DEBUG
     86 static void	 dumpmode __P((BITCMD *));
     87 #endif
     88 
     89 /*
     90  * Given the old mode and an array of bitcmd structures, apply the operations
     91  * described in the bitcmd structures to the old mode, and return the new mode.
     92  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     93  * bits) followed by a '+' (set bits).
     94  */
     95 mode_t
     96 getmode(bbox, omode)
     97 	const void *bbox;
     98 	mode_t omode;
     99 {
    100 	const BITCMD *set;
    101 	mode_t clrval, newmode, value;
    102 
    103 	_DIAGASSERT(bbox != NULL);
    104 
    105 	set = (const BITCMD *)bbox;
    106 	newmode = omode;
    107 	for (value = 0;; set++)
    108 		switch(set->cmd) {
    109 		/*
    110 		 * When copying the user, group or other bits around, we "know"
    111 		 * where the bits are in the mode so that we can do shifts to
    112 		 * copy them around.  If we don't use shifts, it gets real
    113 		 * grundgy with lots of single bit checks and bit sets.
    114 		 */
    115 		case 'u':
    116 			value = (newmode & S_IRWXU) >> 6;
    117 			goto common;
    118 
    119 		case 'g':
    120 			value = (newmode & S_IRWXG) >> 3;
    121 			goto common;
    122 
    123 		case 'o':
    124 			value = newmode & S_IRWXO;
    125 common:			if (set->cmd2 & CMD2_CLR) {
    126 				clrval =
    127 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    128 				if (set->cmd2 & CMD2_UBITS)
    129 					newmode &= ~((clrval<<6) & set->bits);
    130 				if (set->cmd2 & CMD2_GBITS)
    131 					newmode &= ~((clrval<<3) & set->bits);
    132 				if (set->cmd2 & CMD2_OBITS)
    133 					newmode &= ~(clrval & set->bits);
    134 			}
    135 			if (set->cmd2 & CMD2_SET) {
    136 				if (set->cmd2 & CMD2_UBITS)
    137 					newmode |= (value<<6) & set->bits;
    138 				if (set->cmd2 & CMD2_GBITS)
    139 					newmode |= (value<<3) & set->bits;
    140 				if (set->cmd2 & CMD2_OBITS)
    141 					newmode |= value & set->bits;
    142 			}
    143 			break;
    144 
    145 		case '+':
    146 			newmode |= set->bits;
    147 			break;
    148 
    149 		case '-':
    150 			newmode &= ~set->bits;
    151 			break;
    152 
    153 		case 'X':
    154 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    155 				newmode |= set->bits;
    156 			break;
    157 
    158 		case '\0':
    159 		default:
    160 #ifdef SETMODE_DEBUG
    161 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    162 #endif
    163 			return (newmode);
    164 		}
    165 }
    166 
    167 #define	ADDCMD(a, b, c, d) do {						\
    168 	if (set >= endset) {						\
    169 		BITCMD *newset;						\
    170 		setlen += SET_LEN_INCR;					\
    171 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    172 		if (newset == NULL) {					\
    173 			free(saveset);					\
    174 			return (NULL);					\
    175 		}							\
    176 		set = newset + (set - saveset);				\
    177 		saveset = newset;					\
    178 		endset = newset + (setlen - 2);				\
    179 	}								\
    180 	set = addcmd(set, (a), (b), (c), (d));				\
    181 } while (0)
    182 
    183 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    184 
    185 void *
    186 setmode(p)
    187 	const char *p;
    188 {
    189 	int perm, who;
    190 	char op, *ep;
    191 	BITCMD *set, *saveset, *endset;
    192 	sigset_t sigset, sigoset;
    193 	mode_t mask;
    194 	int equalopdone = 0;	/* pacify gcc */
    195 	int permXbits, setlen;
    196 
    197 	if (!*p)
    198 		return (NULL);
    199 
    200 	/*
    201 	 * Get a copy of the mask for the permissions that are mask relative.
    202 	 * Flip the bits, we want what's not set.  Since it's possible that
    203 	 * the caller is opening files inside a signal handler, protect them
    204 	 * as best we can.
    205 	 */
    206 	sigfillset(&sigset);
    207         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    208 	(void)umask(mask = umask(0));
    209 	mask = ~mask;
    210         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    211 
    212 	setlen = SET_LEN + 2;
    213 
    214 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    215 		return (NULL);
    216 	saveset = set;
    217 	endset = set + (setlen - 2);
    218 
    219 	/*
    220 	 * If an absolute number, get it and return; disallow non-octal digits
    221 	 * or illegal bits.
    222 	 */
    223 	if (isdigit((unsigned char)*p)) {
    224 		perm = (mode_t)strtol(p, &ep, 8);
    225 		if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) {
    226 			free(saveset);
    227 			return (NULL);
    228 		}
    229 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    230 		set->cmd = 0;
    231 		return (saveset);
    232 	}
    233 
    234 	/*
    235 	 * Build list of structures to set/clear/copy bits as described by
    236 	 * each clause of the symbolic mode.
    237 	 */
    238 	for (;;) {
    239 		/* First, find out which bits might be modified. */
    240 		for (who = 0;; ++p) {
    241 			switch (*p) {
    242 			case 'a':
    243 				who |= STANDARD_BITS;
    244 				break;
    245 			case 'u':
    246 				who |= S_ISUID|S_IRWXU;
    247 				break;
    248 			case 'g':
    249 				who |= S_ISGID|S_IRWXG;
    250 				break;
    251 			case 'o':
    252 				who |= S_IRWXO;
    253 				break;
    254 			default:
    255 				goto getop;
    256 			}
    257 		}
    258 
    259 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    260 			free(saveset);
    261 			return (NULL);
    262 		}
    263 		if (op == '=')
    264 			equalopdone = 0;
    265 
    266 		who &= ~S_ISTXT;
    267 		for (perm = 0, permXbits = 0;; ++p) {
    268 			switch (*p) {
    269 			case 'r':
    270 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    271 				break;
    272 			case 's':
    273 				/*
    274 				 * If specific bits where requested and
    275 				 * only "other" bits ignore set-id.
    276 				 */
    277 				if (who == 0 || (who & ~S_IRWXO))
    278 					perm |= S_ISUID|S_ISGID;
    279 				break;
    280 			case 't':
    281 				/*
    282 				 * If specific bits where requested and
    283 				 * only "other" bits ignore set-id.
    284 				 */
    285 				if (who == 0 || (who & ~S_IRWXO)) {
    286 					who |= S_ISTXT;
    287 					perm |= S_ISTXT;
    288 				}
    289 				break;
    290 			case 'w':
    291 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    292 				break;
    293 			case 'X':
    294 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    295 				break;
    296 			case 'x':
    297 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    298 				break;
    299 			case 'u':
    300 			case 'g':
    301 			case 'o':
    302 				/*
    303 				 * When ever we hit 'u', 'g', or 'o', we have
    304 				 * to flush out any partial mode that we have,
    305 				 * and then do the copying of the mode bits.
    306 				 */
    307 				if (perm) {
    308 					ADDCMD(op, who, perm, mask);
    309 					perm = 0;
    310 				}
    311 				if (op == '=')
    312 					equalopdone = 1;
    313 				if (op == '+' && permXbits) {
    314 					ADDCMD('X', who, permXbits, mask);
    315 					permXbits = 0;
    316 				}
    317 				ADDCMD(*p, who, op, mask);
    318 				break;
    319 
    320 			default:
    321 				/*
    322 				 * Add any permissions that we haven't already
    323 				 * done.
    324 				 */
    325 				if (perm || (op == '=' && !equalopdone)) {
    326 					if (op == '=')
    327 						equalopdone = 1;
    328 					ADDCMD(op, who, perm, mask);
    329 					perm = 0;
    330 				}
    331 				if (permXbits) {
    332 					ADDCMD('X', who, permXbits, mask);
    333 					permXbits = 0;
    334 				}
    335 				goto apply;
    336 			}
    337 		}
    338 
    339 apply:		if (!*p)
    340 			break;
    341 		if (*p != ',')
    342 			goto getop;
    343 		++p;
    344 	}
    345 	set->cmd = 0;
    346 #ifdef SETMODE_DEBUG
    347 	(void)printf("Before compress_mode()\n");
    348 	dumpmode(saveset);
    349 #endif
    350 	compress_mode(saveset);
    351 #ifdef SETMODE_DEBUG
    352 	(void)printf("After compress_mode()\n");
    353 	dumpmode(saveset);
    354 #endif
    355 	return (saveset);
    356 }
    357 
    358 static BITCMD *
    359 addcmd(set, op, who, oparg, mask)
    360 	BITCMD *set;
    361 	int oparg, who;
    362 	int op;
    363 	u_int mask;
    364 {
    365 
    366 	_DIAGASSERT(set != NULL);
    367 
    368 	switch (op) {
    369 	case '=':
    370 		set->cmd = '-';
    371 		set->bits = who ? who : STANDARD_BITS;
    372 		set++;
    373 
    374 		op = '+';
    375 		/* FALLTHROUGH */
    376 	case '+':
    377 	case '-':
    378 	case 'X':
    379 		set->cmd = op;
    380 		set->bits = (who ? who : mask) & oparg;
    381 		break;
    382 
    383 	case 'u':
    384 	case 'g':
    385 	case 'o':
    386 		set->cmd = op;
    387 		if (who) {
    388 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    389 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    390 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    391 			set->bits = (mode_t)~0;
    392 		} else {
    393 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    394 			set->bits = mask;
    395 		}
    396 
    397 		if (oparg == '+')
    398 			set->cmd2 |= CMD2_SET;
    399 		else if (oparg == '-')
    400 			set->cmd2 |= CMD2_CLR;
    401 		else if (oparg == '=')
    402 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    403 		break;
    404 	}
    405 	return (set + 1);
    406 }
    407 
    408 #ifdef SETMODE_DEBUG
    409 static void
    410 dumpmode(set)
    411 	BITCMD *set;
    412 {
    413 
    414 	_DIAGASSERT(set != NULL);
    415 
    416 	for (; set->cmd; ++set)
    417 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    418 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    419 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    420 		    set->cmd2 & CMD2_SET ? " SET" : "",
    421 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    422 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    423 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    424 }
    425 #endif
    426 
    427 /*
    428  * Given an array of bitcmd structures, compress by compacting consecutive
    429  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    430  * 'g' and 'o' commands continue to be separate.  They could probably be
    431  * compacted, but it's not worth the effort.
    432  */
    433 static void
    434 compress_mode(set)
    435 	BITCMD *set;
    436 {
    437 	BITCMD *nset;
    438 	int setbits, clrbits, Xbits, op;
    439 
    440 	_DIAGASSERT(set != NULL);
    441 
    442 	for (nset = set;;) {
    443 		/* Copy over any 'u', 'g' and 'o' commands. */
    444 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    445 			*set++ = *nset++;
    446 			if (!op)
    447 				return;
    448 		}
    449 
    450 		for (setbits = clrbits = Xbits = 0;; nset++) {
    451 			if ((op = nset->cmd) == '-') {
    452 				clrbits |= nset->bits;
    453 				setbits &= ~nset->bits;
    454 				Xbits &= ~nset->bits;
    455 			} else if (op == '+') {
    456 				setbits |= nset->bits;
    457 				clrbits &= ~nset->bits;
    458 				Xbits &= ~nset->bits;
    459 			} else if (op == 'X')
    460 				Xbits |= nset->bits & ~setbits;
    461 			else
    462 				break;
    463 		}
    464 		if (clrbits) {
    465 			set->cmd = '-';
    466 			set->cmd2 = 0;
    467 			set->bits = clrbits;
    468 			set++;
    469 		}
    470 		if (setbits) {
    471 			set->cmd = '+';
    472 			set->cmd2 = 0;
    473 			set->bits = setbits;
    474 			set++;
    475 		}
    476 		if (Xbits) {
    477 			set->cmd = 'X';
    478 			set->cmd2 = 0;
    479 			set->bits = Xbits;
    480 			set++;
    481 		}
    482 	}
    483 }
    484