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setmode.c revision 1.15 
      1 /*	$NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos 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 #if defined(LIBC_SCCS) && !defined(lint)
     40 #if 0
     41 static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
     42 #else
     43 static char rcsid[] = "$NetBSD: setmode.c,v 1.15 1997/02/07 22:21:06 christos Exp $";
     44 #endif
     45 #endif /* LIBC_SCCS and not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/stat.h>
     49 
     50 #include <ctype.h>
     51 #include <errno.h>
     52 #include <signal.h>
     53 #include <stdlib.h>
     54 #include <unistd.h>
     55 
     56 #ifdef SETMODE_DEBUG
     57 #include <stdio.h>
     58 #endif
     59 
     60 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     61 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     62 
     63 typedef struct bitcmd {
     64 	char	cmd;
     65 	char	cmd2;
     66 	mode_t	bits;
     67 } BITCMD;
     68 
     69 #define	CMD2_CLR	0x01
     70 #define	CMD2_SET	0x02
     71 #define	CMD2_GBITS	0x04
     72 #define	CMD2_OBITS	0x08
     73 #define	CMD2_UBITS	0x10
     74 
     75 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     76 static void	 compress_mode __P((BITCMD *));
     77 #ifdef SETMODE_DEBUG
     78 static void	 dumpmode __P((BITCMD *));
     79 #endif
     80 
     81 /*
     82  * Given the old mode and an array of bitcmd structures, apply the operations
     83  * described in the bitcmd structures to the old mode, and return the new mode.
     84  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     85  * bits) followed by a '+' (set bits).
     86  */
     87 mode_t
     88 getmode(bbox, omode)
     89 	const void *bbox;
     90 	mode_t omode;
     91 {
     92 	register const BITCMD *set;
     93 	register mode_t clrval, newmode, value;
     94 
     95 	set = (const BITCMD *)bbox;
     96 	newmode = omode;
     97 	for (value = 0;; set++)
     98 		switch(set->cmd) {
     99 		/*
    100 		 * When copying the user, group or other bits around, we "know"
    101 		 * where the bits are in the mode so that we can do shifts to
    102 		 * copy them around.  If we don't use shifts, it gets real
    103 		 * grundgy with lots of single bit checks and bit sets.
    104 		 */
    105 		case 'u':
    106 			value = (newmode & S_IRWXU) >> 6;
    107 			goto common;
    108 
    109 		case 'g':
    110 			value = (newmode & S_IRWXG) >> 3;
    111 			goto common;
    112 
    113 		case 'o':
    114 			value = newmode & S_IRWXO;
    115 common:			if (set->cmd2 & CMD2_CLR) {
    116 				clrval =
    117 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    118 				if (set->cmd2 & CMD2_UBITS)
    119 					newmode &= ~((clrval<<6) & set->bits);
    120 				if (set->cmd2 & CMD2_GBITS)
    121 					newmode &= ~((clrval<<3) & set->bits);
    122 				if (set->cmd2 & CMD2_OBITS)
    123 					newmode &= ~(clrval & set->bits);
    124 			}
    125 			if (set->cmd2 & CMD2_SET) {
    126 				if (set->cmd2 & CMD2_UBITS)
    127 					newmode |= (value<<6) & set->bits;
    128 				if (set->cmd2 & CMD2_GBITS)
    129 					newmode |= (value<<3) & set->bits;
    130 				if (set->cmd2 & CMD2_OBITS)
    131 					newmode |= value & set->bits;
    132 			}
    133 			break;
    134 
    135 		case '+':
    136 			newmode |= set->bits;
    137 			break;
    138 
    139 		case '-':
    140 			newmode &= ~set->bits;
    141 			break;
    142 
    143 		case 'X':
    144 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    145 				newmode |= set->bits;
    146 			break;
    147 
    148 		case '\0':
    149 		default:
    150 #ifdef SETMODE_DEBUG
    151 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    152 #endif
    153 			return (newmode);
    154 		}
    155 }
    156 
    157 #define	ADDCMD(a, b, c, d)						\
    158 	if (set >= endset) {						\
    159 		register BITCMD *newset;				\
    160 		setlen += SET_LEN_INCR;					\
    161 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    162 		if (!saveset)						\
    163 			return (NULL);					\
    164 		set = newset + (set - saveset);				\
    165 		saveset = newset;					\
    166 		endset = newset + (setlen - 2);				\
    167 	}								\
    168 	set = addcmd(set, (a), (b), (c), (d))
    169 
    170 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    171 
    172 void *
    173 setmode(p)
    174 	register const char *p;
    175 {
    176 	register int perm, who;
    177 	register char op;
    178 	BITCMD *set, *saveset, *endset;
    179 	sigset_t sigset, sigoset;
    180 	mode_t mask;
    181 	int equalopdone, permXbits, setlen;
    182 
    183 	if (!*p)
    184 		return (NULL);
    185 
    186 	/*
    187 	 * Get a copy of the mask for the permissions that are mask relative.
    188 	 * Flip the bits, we want what's not set.  Since it's possible that
    189 	 * the caller is opening files inside a signal handler, protect them
    190 	 * as best we can.
    191 	 */
    192 	sigfillset(&sigset);
    193         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    194 	(void)umask(mask = umask(0));
    195 	mask = ~mask;
    196         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    197 
    198 	setlen = SET_LEN + 2;
    199 
    200 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    201 		return (NULL);
    202 	saveset = set;
    203 	endset = set + (setlen - 2);
    204 
    205 	/*
    206 	 * If an absolute number, get it and return; disallow non-octal digits
    207 	 * or illegal bits.
    208 	 */
    209 	if (isdigit(*p)) {
    210 		perm = (mode_t)strtol(p, NULL, 8);
    211 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    212 			free(saveset);
    213 			return (NULL);
    214 		}
    215 		while (*++p)
    216 			if (*p < '0' || *p > '7') {
    217 				free(saveset);
    218 				return (NULL);
    219 			}
    220 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    221 		return (saveset);
    222 	}
    223 
    224 	/*
    225 	 * Build list of structures to set/clear/copy bits as described by
    226 	 * each clause of the symbolic mode.
    227 	 */
    228 	for (;;) {
    229 		/* First, find out which bits might be modified. */
    230 		for (who = 0;; ++p) {
    231 			switch (*p) {
    232 			case 'a':
    233 				who |= STANDARD_BITS;
    234 				break;
    235 			case 'u':
    236 				who |= S_ISUID|S_IRWXU;
    237 				break;
    238 			case 'g':
    239 				who |= S_ISGID|S_IRWXG;
    240 				break;
    241 			case 'o':
    242 				who |= S_IRWXO;
    243 				break;
    244 			default:
    245 				goto getop;
    246 			}
    247 		}
    248 
    249 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    250 			free(saveset);
    251 			return (NULL);
    252 		}
    253 		if (op == '=')
    254 			equalopdone = 0;
    255 
    256 		who &= ~S_ISTXT;
    257 		for (perm = 0, permXbits = 0;; ++p) {
    258 			switch (*p) {
    259 			case 'r':
    260 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    261 				break;
    262 			case 's':
    263 				/*
    264 				 * If specific bits where requested and
    265 				 * only "other" bits ignore set-id.
    266 				 */
    267 				if (who == 0 || (who & ~S_IRWXO))
    268 					perm |= S_ISUID|S_ISGID;
    269 				break;
    270 			case 't':
    271 				/*
    272 				 * If specific bits where requested and
    273 				 * only "other" bits ignore set-id.
    274 				 */
    275 				if (who == 0 || (who & ~S_IRWXO)) {
    276 					who |= S_ISTXT;
    277 					perm |= S_ISTXT;
    278 				}
    279 				break;
    280 			case 'w':
    281 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    282 				break;
    283 			case 'X':
    284 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    285 				break;
    286 			case 'x':
    287 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    288 				break;
    289 			case 'u':
    290 			case 'g':
    291 			case 'o':
    292 				/*
    293 				 * When ever we hit 'u', 'g', or 'o', we have
    294 				 * to flush out any partial mode that we have,
    295 				 * and then do the copying of the mode bits.
    296 				 */
    297 				if (perm) {
    298 					ADDCMD(op, who, perm, mask);
    299 					perm = 0;
    300 				}
    301 				if (op == '=')
    302 					equalopdone = 1;
    303 				if (op == '+' && permXbits) {
    304 					ADDCMD('X', who, permXbits, mask);
    305 					permXbits = 0;
    306 				}
    307 				ADDCMD(*p, who, op, mask);
    308 				break;
    309 
    310 			default:
    311 				/*
    312 				 * Add any permissions that we haven't already
    313 				 * done.
    314 				 */
    315 				if (perm || (op == '=' && !equalopdone)) {
    316 					if (op == '=')
    317 						equalopdone = 1;
    318 					ADDCMD(op, who, perm, mask);
    319 					perm = 0;
    320 				}
    321 				if (permXbits) {
    322 					ADDCMD('X', who, permXbits, mask);
    323 					permXbits = 0;
    324 				}
    325 				goto apply;
    326 			}
    327 		}
    328 
    329 apply:		if (!*p)
    330 			break;
    331 		if (*p != ',')
    332 			goto getop;
    333 		++p;
    334 	}
    335 	set->cmd = 0;
    336 #ifdef SETMODE_DEBUG
    337 	(void)printf("Before compress_mode()\n");
    338 	dumpmode(saveset);
    339 #endif
    340 	compress_mode(saveset);
    341 #ifdef SETMODE_DEBUG
    342 	(void)printf("After compress_mode()\n");
    343 	dumpmode(saveset);
    344 #endif
    345 	return (saveset);
    346 }
    347 
    348 static BITCMD *
    349 addcmd(set, op, who, oparg, mask)
    350 	BITCMD *set;
    351 	register int oparg, who;
    352 	register int op;
    353 	u_int mask;
    354 {
    355 	switch (op) {
    356 	case '=':
    357 		set->cmd = '-';
    358 		set->bits = who ? who : STANDARD_BITS;
    359 		set++;
    360 
    361 		op = '+';
    362 		/* FALLTHROUGH */
    363 	case '+':
    364 	case '-':
    365 	case 'X':
    366 		set->cmd = op;
    367 		set->bits = (who ? who : mask) & oparg;
    368 		break;
    369 
    370 	case 'u':
    371 	case 'g':
    372 	case 'o':
    373 		set->cmd = op;
    374 		if (who) {
    375 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    376 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    377 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    378 			set->bits = ~0;
    379 		} else {
    380 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    381 			set->bits = mask;
    382 		}
    383 
    384 		if (oparg == '+')
    385 			set->cmd2 |= CMD2_SET;
    386 		else if (oparg == '-')
    387 			set->cmd2 |= CMD2_CLR;
    388 		else if (oparg == '=')
    389 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    390 		break;
    391 	}
    392 	return (set + 1);
    393 }
    394 
    395 #ifdef SETMODE_DEBUG
    396 static void
    397 dumpmode(set)
    398 	register BITCMD *set;
    399 {
    400 	for (; set->cmd; ++set)
    401 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    402 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    403 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    404 		    set->cmd2 & CMD2_SET ? " SET" : "",
    405 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    406 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    407 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    408 }
    409 #endif
    410 
    411 /*
    412  * Given an array of bitcmd structures, compress by compacting consecutive
    413  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    414  * 'g' and 'o' commands continue to be separate.  They could probably be
    415  * compacted, but it's not worth the effort.
    416  */
    417 static void
    418 compress_mode(set)
    419 	register BITCMD *set;
    420 {
    421 	register BITCMD *nset;
    422 	register int setbits, clrbits, Xbits, op;
    423 
    424 	for (nset = set;;) {
    425 		/* Copy over any 'u', 'g' and 'o' commands. */
    426 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    427 			*set++ = *nset++;
    428 			if (!op)
    429 				return;
    430 		}
    431 
    432 		for (setbits = clrbits = Xbits = 0;; nset++) {
    433 			if ((op = nset->cmd) == '-') {
    434 				clrbits |= nset->bits;
    435 				setbits &= ~nset->bits;
    436 				Xbits &= ~nset->bits;
    437 			} else if (op == '+') {
    438 				setbits |= nset->bits;
    439 				clrbits &= ~nset->bits;
    440 				Xbits &= ~nset->bits;
    441 			} else if (op == 'X')
    442 				Xbits |= nset->bits & ~setbits;
    443 			else
    444 				break;
    445 		}
    446 		if (clrbits) {
    447 			set->cmd = '-';
    448 			set->cmd2 = 0;
    449 			set->bits = clrbits;
    450 			set++;
    451 		}
    452 		if (setbits) {
    453 			set->cmd = '+';
    454 			set->cmd2 = 0;
    455 			set->bits = setbits;
    456 			set++;
    457 		}
    458 		if (Xbits) {
    459 			set->cmd = 'X';
    460 			set->cmd2 = 0;
    461 			set->bits = Xbits;
    462 			set++;
    463 		}
    464 	}
    465 }
    466