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setmode.c revision 1.9 
      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 /* from: static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94"; */
     39 static char *rcsid = "$Id: setmode.c,v 1.9 1994/03/29 10:50:38 cgd Exp $";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <sys/types.h>
     43 #include <sys/stat.h>
     44 
     45 #include <ctype.h>
     46 #include <errno.h>
     47 #include <signal.h>
     48 #include <stddef.h>
     49 #include <stdlib.h>
     50 
     51 #ifdef SETMODE_DEBUG
     52 #include <stdio.h>
     53 #endif
     54 
     55 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     56 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     57 
     58 typedef struct bitcmd {
     59 	char	cmd;
     60 	char	cmd2;
     61 	mode_t	bits;
     62 } BITCMD;
     63 
     64 #define	CMD2_CLR	0x01
     65 #define	CMD2_SET	0x02
     66 #define	CMD2_GBITS	0x04
     67 #define	CMD2_OBITS	0x08
     68 #define	CMD2_UBITS	0x10
     69 
     70 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     71 static int	 compress_mode __P((BITCMD *));
     72 #ifdef SETMODE_DEBUG
     73 static void	 dumpmode __P((BITCMD *));
     74 #endif
     75 
     76 /*
     77  * Given the old mode and an array of bitcmd structures, apply the operations
     78  * described in the bitcmd structures to the old mode, and return the new mode.
     79  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     80  * bits) followed by a '+' (set bits).
     81  */
     82 mode_t
     83 getmode(bbox, omode)
     84 	void *bbox;
     85 	mode_t omode;
     86 {
     87 	register BITCMD *set;
     88 	register mode_t clrval, newmode, value;
     89 
     90 	set = (BITCMD *)bbox;
     91 	newmode = omode;
     92 	for (value = 0;; set++)
     93 		switch(set->cmd) {
     94 		/*
     95 		 * When copying the user, group or other bits around, we "know"
     96 		 * where the bits are in the mode so that we can do shifts to
     97 		 * copy them around.  If we don't use shifts, it gets real
     98 		 * grundgy with lots of single bit checks and bit sets.
     99 		 */
    100 		case 'u':
    101 			value = (newmode & S_IRWXU) >> 6;
    102 			goto common;
    103 
    104 		case 'g':
    105 			value = (newmode & S_IRWXG) >> 3;
    106 			goto common;
    107 
    108 		case 'o':
    109 			value = newmode & S_IRWXO;
    110 common:			if (set->cmd2 & CMD2_CLR) {
    111 				clrval =
    112 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    113 				if (set->cmd2 & CMD2_UBITS)
    114 					newmode &= ~((clrval<<6) & set->bits);
    115 				if (set->cmd2 & CMD2_GBITS)
    116 					newmode &= ~((clrval<<3) & set->bits);
    117 				if (set->cmd2 & CMD2_OBITS)
    118 					newmode &= ~(clrval & set->bits);
    119 			}
    120 			if (set->cmd2 & CMD2_SET) {
    121 				if (set->cmd2 & CMD2_UBITS)
    122 					newmode |= (value<<6) & set->bits;
    123 				if (set->cmd2 & CMD2_GBITS)
    124 					newmode |= (value<<3) & set->bits;
    125 				if (set->cmd2 & CMD2_OBITS)
    126 					newmode |= value & set->bits;
    127 			}
    128 			break;
    129 
    130 		case '+':
    131 			newmode |= set->bits;
    132 			break;
    133 
    134 		case '-':
    135 			newmode &= ~set->bits;
    136 			break;
    137 
    138 		case 'X':
    139 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    140 				newmode |= set->bits;
    141 			break;
    142 
    143 		case '\0':
    144 		default:
    145 #ifdef SETMODE_DEBUG
    146 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    147 #endif
    148 			return (newmode);
    149 		}
    150 }
    151 
    152 #define	ADDCMD(a, b, c, d)						\
    153 	if (set >= endset) {						\
    154 		register BITCMD *newset;				\
    155 		setlen += SET_LEN_INCR;					\
    156 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    157 		if (!saveset)						\
    158 			return (NULL);					\
    159 		set = newset + (set - saveset);				\
    160 		saveset = newset;					\
    161 		endset = newset + (setlen - 2);				\
    162 	}								\
    163 	set = addcmd(set, (a), (b), (c), (d))
    164 
    165 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    166 
    167 void *
    168 setmode(p)
    169 	register char *p;
    170 {
    171 	register int perm, who;
    172 	register char op;
    173 	BITCMD *set, *saveset, *endset;
    174 	sigset_t sigset, sigoset;
    175 	mode_t mask;
    176 	int equalopdone, permXbits, setlen;
    177 
    178 	if (!*p)
    179 		return (NULL);
    180 
    181 	/*
    182 	 * Get a copy of the mask for the permissions that are mask relative.
    183 	 * Flip the bits, we want what's not set.  Since it's possible that
    184 	 * the caller is opening files inside a signal handler, protect them
    185 	 * as best we can.
    186 	 */
    187 	sigfillset(&sigset);
    188         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    189 	(void)umask(mask = umask(0));
    190 	mask = ~mask;
    191         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    192 
    193 	setlen = SET_LEN + 2;
    194 
    195 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    196 		return (NULL);
    197 	saveset = set;
    198 	endset = set + (setlen - 2);
    199 
    200 	/*
    201 	 * If an absolute number, get it and return; disallow non-octal digits
    202 	 * or illegal bits.
    203 	 */
    204 	if (isdigit(*p)) {
    205 		perm = (mode_t)strtol(p, NULL, 8);
    206 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    207 			free(saveset);
    208 			return (NULL);
    209 		}
    210 		while (*++p)
    211 			if (*p < '0' || *p > '7') {
    212 				free(saveset);
    213 				return (NULL);
    214 			}
    215 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    216 		return (saveset);
    217 	}
    218 
    219 	/*
    220 	 * Build list of structures to set/clear/copy bits as described by
    221 	 * each clause of the symbolic mode.
    222 	 */
    223 	for (;;) {
    224 		/* First, find out which bits might be modified. */
    225 		for (who = 0;; ++p) {
    226 			switch (*p) {
    227 			case 'a':
    228 				who |= STANDARD_BITS;
    229 				break;
    230 			case 'u':
    231 				who |= S_ISUID|S_IRWXU;
    232 				break;
    233 			case 'g':
    234 				who |= S_ISGID|S_IRWXG;
    235 				break;
    236 			case 'o':
    237 				who |= S_IRWXO;
    238 				break;
    239 			default:
    240 				goto getop;
    241 			}
    242 		}
    243 
    244 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    245 			free(saveset);
    246 			return (NULL);
    247 		}
    248 		if (op == '=')
    249 			equalopdone = 0;
    250 
    251 		who &= ~S_ISTXT;
    252 		for (perm = 0, permXbits = 0;; ++p) {
    253 			switch (*p) {
    254 			case 'r':
    255 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    256 				break;
    257 			case 's':
    258 				/* If only "other" bits ignore set-id. */
    259 				if (who & ~S_IRWXO)
    260 					perm |= S_ISUID|S_ISGID;
    261 				break;
    262 			case 't':
    263 				/* If only "other" bits ignore sticky. */
    264 				if (who & ~S_IRWXO) {
    265 					who |= S_ISTXT;
    266 					perm |= S_ISTXT;
    267 				}
    268 				break;
    269 			case 'w':
    270 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    271 				break;
    272 			case 'X':
    273 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    274 				break;
    275 			case 'x':
    276 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    277 				break;
    278 			case 'u':
    279 			case 'g':
    280 			case 'o':
    281 				/*
    282 				 * When ever we hit 'u', 'g', or 'o', we have
    283 				 * to flush out any partial mode that we have,
    284 				 * and then do the copying of the mode bits.
    285 				 */
    286 				if (perm) {
    287 					ADDCMD(op, who, perm, mask);
    288 					perm = 0;
    289 				}
    290 				if (op == '=')
    291 					equalopdone = 1;
    292 				if (op == '+' && permXbits) {
    293 					ADDCMD('X', who, permXbits, mask);
    294 					permXbits = 0;
    295 				}
    296 				ADDCMD(*p, who, op, mask);
    297 				break;
    298 
    299 			default:
    300 				/*
    301 				 * Add any permissions that we haven't already
    302 				 * done.
    303 				 */
    304 				if (perm || (op == '=' && !equalopdone)) {
    305 					if (op == '=')
    306 						equalopdone = 1;
    307 					ADDCMD(op, who, perm, mask);
    308 					perm = 0;
    309 				}
    310 				if (permXbits) {
    311 					ADDCMD('X', who, permXbits, mask);
    312 					permXbits = 0;
    313 				}
    314 				goto apply;
    315 			}
    316 		}
    317 
    318 apply:		if (!*p)
    319 			break;
    320 		if (*p != ',')
    321 			goto getop;
    322 		++p;
    323 	}
    324 	set->cmd = 0;
    325 #ifdef SETMODE_DEBUG
    326 	(void)printf("Before compress_mode()\n");
    327 	dumpmode(saveset);
    328 #endif
    329 	compress_mode(saveset);
    330 #ifdef SETMODE_DEBUG
    331 	(void)printf("After compress_mode()\n");
    332 	dumpmode(saveset);
    333 #endif
    334 	return (saveset);
    335 }
    336 
    337 static BITCMD *
    338 addcmd(set, op, who, oparg, mask)
    339 	BITCMD *set;
    340 	register int oparg, who;
    341 	register int op;
    342 	u_int mask;
    343 {
    344 	switch (op) {
    345 	case '=':
    346 		set->cmd = '-';
    347 		set->bits = who ? who : STANDARD_BITS;
    348 		set++;
    349 
    350 		op = '+';
    351 		/* FALLTHROUGH */
    352 	case '+':
    353 	case '-':
    354 	case 'X':
    355 		set->cmd = op;
    356 		set->bits = (who ? who : mask) & oparg;
    357 		break;
    358 
    359 	case 'u':
    360 	case 'g':
    361 	case 'o':
    362 		set->cmd = op;
    363 		if (who) {
    364 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    365 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    366 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    367 			set->bits = ~0;
    368 		} else {
    369 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    370 			set->bits = mask;
    371 		}
    372 
    373 		if (oparg == '+')
    374 			set->cmd2 |= CMD2_SET;
    375 		else if (oparg == '-')
    376 			set->cmd2 |= CMD2_CLR;
    377 		else if (oparg == '=')
    378 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    379 		break;
    380 	}
    381 	return (set + 1);
    382 }
    383 
    384 #ifdef SETMODE_DEBUG
    385 static void
    386 dumpmode(set)
    387 	register BITCMD *set;
    388 {
    389 	for (; set->cmd; ++set)
    390 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    391 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    392 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    393 		    set->cmd2 & CMD2_SET ? " SET" : "",
    394 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    395 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    396 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    397 }
    398 #endif
    399 
    400 /*
    401  * Given an array of bitcmd structures, compress by compacting consecutive
    402  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    403  * 'g' and 'o' commands continue to be separate.  They could probably be
    404  * compacted, but it's not worth the effort.
    405  */
    406 static int
    407 compress_mode(set)
    408 	register BITCMD *set;
    409 {
    410 	register BITCMD *nset;
    411 	register int setbits, clrbits, Xbits, op;
    412 
    413 	for (nset = set;;) {
    414 		/* Copy over any 'u', 'g' and 'o' commands. */
    415 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    416 			*set++ = *nset++;
    417 			if (!op)
    418 				return;
    419 		}
    420 
    421 		for (setbits = clrbits = Xbits = 0;; nset++) {
    422 			if ((op = nset->cmd) == '-') {
    423 				clrbits |= nset->bits;
    424 				setbits &= ~nset->bits;
    425 				Xbits &= ~nset->bits;
    426 			} else if (op == '+') {
    427 				setbits |= nset->bits;
    428 				clrbits &= ~nset->bits;
    429 				Xbits &= ~nset->bits;
    430 			} else if (op == 'X')
    431 				Xbits |= nset->bits & ~setbits;
    432 			else
    433 				break;
    434 		}
    435 		if (clrbits) {
    436 			set->cmd = '-';
    437 			set->cmd2 = 0;
    438 			set->bits = clrbits;
    439 			set++;
    440 		}
    441 		if (setbits) {
    442 			set->cmd = '+';
    443 			set->cmd2 = 0;
    444 			set->bits = setbits;
    445 			set++;
    446 		}
    447 		if (Xbits) {
    448 			set->cmd = 'X';
    449 			set->cmd2 = 0;
    450 			set->bits = Xbits;
    451 			set++;
    452 		}
    453 	}
    454 }
    455