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setmode.c revision 1.1.1.2 
      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 static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <sys/types.h>
     42 #include <sys/stat.h>
     43 
     44 #include <ctype.h>
     45 #include <errno.h>
     46 #include <signal.h>
     47 #include <stddef.h>
     48 #include <stdlib.h>
     49 
     50 #ifdef SETMODE_DEBUG
     51 #include <stdio.h>
     52 #endif
     53 
     54 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     55 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     56 
     57 typedef struct bitcmd {
     58 	char	cmd;
     59 	char	cmd2;
     60 	mode_t	bits;
     61 } BITCMD;
     62 
     63 #define	CMD2_CLR	0x01
     64 #define	CMD2_SET	0x02
     65 #define	CMD2_GBITS	0x04
     66 #define	CMD2_OBITS	0x08
     67 #define	CMD2_UBITS	0x10
     68 
     69 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     70 static int	 compress_mode __P((BITCMD *));
     71 #ifdef SETMODE_DEBUG
     72 static void	 dumpmode __P((BITCMD *));
     73 #endif
     74 
     75 /*
     76  * Given the old mode and an array of bitcmd structures, apply the operations
     77  * described in the bitcmd structures to the old mode, and return the new mode.
     78  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     79  * bits) followed by a '+' (set bits).
     80  */
     81 mode_t
     82 getmode(bbox, omode)
     83 	void *bbox;
     84 	mode_t omode;
     85 {
     86 	register BITCMD *set;
     87 	register mode_t clrval, newmode, value;
     88 
     89 	set = (BITCMD *)bbox;
     90 	newmode = omode;
     91 	for (value = 0;; set++)
     92 		switch(set->cmd) {
     93 		/*
     94 		 * When copying the user, group or other bits around, we "know"
     95 		 * where the bits are in the mode so that we can do shifts to
     96 		 * copy them around.  If we don't use shifts, it gets real
     97 		 * grundgy with lots of single bit checks and bit sets.
     98 		 */
     99 		case 'u':
    100 			value = (newmode & S_IRWXU) >> 6;
    101 			goto common;
    102 
    103 		case 'g':
    104 			value = (newmode & S_IRWXG) >> 3;
    105 			goto common;
    106 
    107 		case 'o':
    108 			value = newmode & S_IRWXO;
    109 common:			if (set->cmd2 & CMD2_CLR) {
    110 				clrval =
    111 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    112 				if (set->cmd2 & CMD2_UBITS)
    113 					newmode &= ~((clrval<<6) & set->bits);
    114 				if (set->cmd2 & CMD2_GBITS)
    115 					newmode &= ~((clrval<<3) & set->bits);
    116 				if (set->cmd2 & CMD2_OBITS)
    117 					newmode &= ~(clrval & set->bits);
    118 			}
    119 			if (set->cmd2 & CMD2_SET) {
    120 				if (set->cmd2 & CMD2_UBITS)
    121 					newmode |= (value<<6) & set->bits;
    122 				if (set->cmd2 & CMD2_GBITS)
    123 					newmode |= (value<<3) & set->bits;
    124 				if (set->cmd2 & CMD2_OBITS)
    125 					newmode |= value & set->bits;
    126 			}
    127 			break;
    128 
    129 		case '+':
    130 			newmode |= set->bits;
    131 			break;
    132 
    133 		case '-':
    134 			newmode &= ~set->bits;
    135 			break;
    136 
    137 		case 'X':
    138 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    139 				newmode |= set->bits;
    140 			break;
    141 
    142 		case '\0':
    143 		default:
    144 #ifdef SETMODE_DEBUG
    145 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    146 #endif
    147 			return (newmode);
    148 		}
    149 }
    150 
    151 #define	ADDCMD(a, b, c, d)						\
    152 	if (set >= endset) {						\
    153 		register BITCMD *newset;				\
    154 		setlen += SET_LEN_INCR;					\
    155 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    156 		if (!saveset)						\
    157 			return (NULL);					\
    158 		set = newset + (set - saveset);				\
    159 		saveset = newset;					\
    160 		endset = newset + (setlen - 2);				\
    161 	}								\
    162 	set = addcmd(set, (a), (b), (c), (d))
    163 
    164 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    165 
    166 void *
    167 setmode(p)
    168 	register char *p;
    169 {
    170 	register int perm, who;
    171 	register char op;
    172 	BITCMD *set, *saveset, *endset;
    173 	sigset_t sigset, sigoset;
    174 	mode_t mask;
    175 	int equalopdone, permXbits, setlen;
    176 
    177 	if (!*p)
    178 		return (NULL);
    179 
    180 	/*
    181 	 * Get a copy of the mask for the permissions that are mask relative.
    182 	 * Flip the bits, we want what's not set.  Since it's possible that
    183 	 * the caller is opening files inside a signal handler, protect them
    184 	 * as best we can.
    185 	 */
    186 	sigfillset(&sigset);
    187         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    188 	(void)umask(mask = umask(0));
    189 	mask = ~mask;
    190         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    191 
    192 	setlen = SET_LEN + 2;
    193 
    194 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    195 		return (NULL);
    196 	saveset = set;
    197 	endset = set + (setlen - 2);
    198 
    199 	/*
    200 	 * If an absolute number, get it and return; disallow non-octal digits
    201 	 * or illegal bits.
    202 	 */
    203 	if (isdigit(*p)) {
    204 		perm = (mode_t)strtol(p, NULL, 8);
    205 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    206 			free(saveset);
    207 			return (NULL);
    208 		}
    209 		while (*++p)
    210 			if (*p < '0' || *p > '7') {
    211 				free(saveset);
    212 				return (NULL);
    213 			}
    214 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    215 		return (saveset);
    216 	}
    217 
    218 	/*
    219 	 * Build list of structures to set/clear/copy bits as described by
    220 	 * each clause of the symbolic mode.
    221 	 */
    222 	for (;;) {
    223 		/* First, find out which bits might be modified. */
    224 		for (who = 0;; ++p) {
    225 			switch (*p) {
    226 			case 'a':
    227 				who |= STANDARD_BITS;
    228 				break;
    229 			case 'u':
    230 				who |= S_ISUID|S_IRWXU;
    231 				break;
    232 			case 'g':
    233 				who |= S_ISGID|S_IRWXG;
    234 				break;
    235 			case 'o':
    236 				who |= S_IRWXO;
    237 				break;
    238 			default:
    239 				goto getop;
    240 			}
    241 		}
    242 
    243 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    244 			free(saveset);
    245 			return (NULL);
    246 		}
    247 		if (op == '=')
    248 			equalopdone = 0;
    249 
    250 		who &= ~S_ISTXT;
    251 		for (perm = 0, permXbits = 0;; ++p) {
    252 			switch (*p) {
    253 			case 'r':
    254 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    255 				break;
    256 			case 's':
    257 				/* If only "other" bits ignore set-id. */
    258 				if (who & ~S_IRWXO)
    259 					perm |= S_ISUID|S_ISGID;
    260 				break;
    261 			case 't':
    262 				/* If only "other" bits ignore sticky. */
    263 				if (who & ~S_IRWXO) {
    264 					who |= S_ISTXT;
    265 					perm |= S_ISTXT;
    266 				}
    267 				break;
    268 			case 'w':
    269 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    270 				break;
    271 			case 'X':
    272 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    273 				break;
    274 			case 'x':
    275 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    276 				break;
    277 			case 'u':
    278 			case 'g':
    279 			case 'o':
    280 				/*
    281 				 * When ever we hit 'u', 'g', or 'o', we have
    282 				 * to flush out any partial mode that we have,
    283 				 * and then do the copying of the mode bits.
    284 				 */
    285 				if (perm) {
    286 					ADDCMD(op, who, perm, mask);
    287 					perm = 0;
    288 				}
    289 				if (op == '=')
    290 					equalopdone = 1;
    291 				if (op == '+' && permXbits) {
    292 					ADDCMD('X', who, permXbits, mask);
    293 					permXbits = 0;
    294 				}
    295 				ADDCMD(*p, who, op, mask);
    296 				break;
    297 
    298 			default:
    299 				/*
    300 				 * Add any permissions that we haven't already
    301 				 * done.
    302 				 */
    303 				if (perm || (op == '=' && !equalopdone)) {
    304 					if (op == '=')
    305 						equalopdone = 1;
    306 					ADDCMD(op, who, perm, mask);
    307 					perm = 0;
    308 				}
    309 				if (permXbits) {
    310 					ADDCMD('X', who, permXbits, mask);
    311 					permXbits = 0;
    312 				}
    313 				goto apply;
    314 			}
    315 		}
    316 
    317 apply:		if (!*p)
    318 			break;
    319 		if (*p != ',')
    320 			goto getop;
    321 		++p;
    322 	}
    323 	set->cmd = 0;
    324 #ifdef SETMODE_DEBUG
    325 	(void)printf("Before compress_mode()\n");
    326 	dumpmode(saveset);
    327 #endif
    328 	compress_mode(saveset);
    329 #ifdef SETMODE_DEBUG
    330 	(void)printf("After compress_mode()\n");
    331 	dumpmode(saveset);
    332 #endif
    333 	return (saveset);
    334 }
    335 
    336 static BITCMD *
    337 addcmd(set, op, who, oparg, mask)
    338 	BITCMD *set;
    339 	register int oparg, who;
    340 	register int op;
    341 	u_int mask;
    342 {
    343 	switch (op) {
    344 	case '=':
    345 		set->cmd = '-';
    346 		set->bits = who ? who : STANDARD_BITS;
    347 		set++;
    348 
    349 		op = '+';
    350 		/* FALLTHROUGH */
    351 	case '+':
    352 	case '-':
    353 	case 'X':
    354 		set->cmd = op;
    355 		set->bits = (who ? who : mask) & oparg;
    356 		break;
    357 
    358 	case 'u':
    359 	case 'g':
    360 	case 'o':
    361 		set->cmd = op;
    362 		if (who) {
    363 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    364 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    365 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    366 			set->bits = ~0;
    367 		} else {
    368 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    369 			set->bits = mask;
    370 		}
    371 
    372 		if (oparg == '+')
    373 			set->cmd2 |= CMD2_SET;
    374 		else if (oparg == '-')
    375 			set->cmd2 |= CMD2_CLR;
    376 		else if (oparg == '=')
    377 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    378 		break;
    379 	}
    380 	return (set + 1);
    381 }
    382 
    383 #ifdef SETMODE_DEBUG
    384 static void
    385 dumpmode(set)
    386 	register BITCMD *set;
    387 {
    388 	for (; set->cmd; ++set)
    389 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    390 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    391 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    392 		    set->cmd2 & CMD2_SET ? " SET" : "",
    393 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    394 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    395 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    396 }
    397 #endif
    398 
    399 /*
    400  * Given an array of bitcmd structures, compress by compacting consecutive
    401  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    402  * 'g' and 'o' commands continue to be separate.  They could probably be
    403  * compacted, but it's not worth the effort.
    404  */
    405 static int
    406 compress_mode(set)
    407 	register BITCMD *set;
    408 {
    409 	register BITCMD *nset;
    410 	register int setbits, clrbits, Xbits, op;
    411 
    412 	for (nset = set;;) {
    413 		/* Copy over any 'u', 'g' and 'o' commands. */
    414 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    415 			*set++ = *nset++;
    416 			if (!op)
    417 				return;
    418 		}
    419 
    420 		for (setbits = clrbits = Xbits = 0;; nset++) {
    421 			if ((op = nset->cmd) == '-') {
    422 				clrbits |= nset->bits;
    423 				setbits &= ~nset->bits;
    424 				Xbits &= ~nset->bits;
    425 			} else if (op == '+') {
    426 				setbits |= nset->bits;
    427 				clrbits &= ~nset->bits;
    428 				Xbits &= ~nset->bits;
    429 			} else if (op == 'X')
    430 				Xbits |= nset->bits & ~setbits;
    431 			else
    432 				break;
    433 		}
    434 		if (clrbits) {
    435 			set->cmd = '-';
    436 			set->cmd2 = 0;
    437 			set->bits = clrbits;
    438 			set++;
    439 		}
    440 		if (setbits) {
    441 			set->cmd = '+';
    442 			set->cmd2 = 0;
    443 			set->bits = setbits;
    444 			set++;
    445 		}
    446 		if (Xbits) {
    447 			set->cmd = 'X';
    448 			set->cmd2 = 0;
    449 			set->bits = Xbits;
    450 			set++;
    451 		}
    452 	}
    453 }
    454