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setmode.c revision 1.9.4.1 
      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 1.9.4.1 1995/05/02 19:35:08 jtc Exp $";
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include "namespace.h"
     43 #include <sys/types.h>
     44 #include <sys/stat.h>
     45 
     46 #include <ctype.h>
     47 #include <errno.h>
     48 #include <signal.h>
     49 #include <stddef.h>
     50 #include <stdlib.h>
     51 
     52 #ifdef SETMODE_DEBUG
     53 #include <stdio.h>
     54 #endif
     55 
     56 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     57 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     58 
     59 typedef struct bitcmd {
     60 	char	cmd;
     61 	char	cmd2;
     62 	mode_t	bits;
     63 } BITCMD;
     64 
     65 #define	CMD2_CLR	0x01
     66 #define	CMD2_SET	0x02
     67 #define	CMD2_GBITS	0x04
     68 #define	CMD2_OBITS	0x08
     69 #define	CMD2_UBITS	0x10
     70 
     71 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     72 static int	 compress_mode __P((BITCMD *));
     73 #ifdef SETMODE_DEBUG
     74 static void	 dumpmode __P((BITCMD *));
     75 #endif
     76 
     77 /*
     78  * Given the old mode and an array of bitcmd structures, apply the operations
     79  * described in the bitcmd structures to the old mode, and return the new mode.
     80  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     81  * bits) followed by a '+' (set bits).
     82  */
     83 mode_t
     84 getmode(bbox, omode)
     85 	void *bbox;
     86 	mode_t omode;
     87 {
     88 	register BITCMD *set;
     89 	register mode_t clrval, newmode, value;
     90 
     91 	set = (BITCMD *)bbox;
     92 	newmode = omode;
     93 	for (value = 0;; set++)
     94 		switch(set->cmd) {
     95 		/*
     96 		 * When copying the user, group or other bits around, we "know"
     97 		 * where the bits are in the mode so that we can do shifts to
     98 		 * copy them around.  If we don't use shifts, it gets real
     99 		 * grundgy with lots of single bit checks and bit sets.
    100 		 */
    101 		case 'u':
    102 			value = (newmode & S_IRWXU) >> 6;
    103 			goto common;
    104 
    105 		case 'g':
    106 			value = (newmode & S_IRWXG) >> 3;
    107 			goto common;
    108 
    109 		case 'o':
    110 			value = newmode & S_IRWXO;
    111 common:			if (set->cmd2 & CMD2_CLR) {
    112 				clrval =
    113 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    114 				if (set->cmd2 & CMD2_UBITS)
    115 					newmode &= ~((clrval<<6) & set->bits);
    116 				if (set->cmd2 & CMD2_GBITS)
    117 					newmode &= ~((clrval<<3) & set->bits);
    118 				if (set->cmd2 & CMD2_OBITS)
    119 					newmode &= ~(clrval & set->bits);
    120 			}
    121 			if (set->cmd2 & CMD2_SET) {
    122 				if (set->cmd2 & CMD2_UBITS)
    123 					newmode |= (value<<6) & set->bits;
    124 				if (set->cmd2 & CMD2_GBITS)
    125 					newmode |= (value<<3) & set->bits;
    126 				if (set->cmd2 & CMD2_OBITS)
    127 					newmode |= value & set->bits;
    128 			}
    129 			break;
    130 
    131 		case '+':
    132 			newmode |= set->bits;
    133 			break;
    134 
    135 		case '-':
    136 			newmode &= ~set->bits;
    137 			break;
    138 
    139 		case 'X':
    140 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    141 				newmode |= set->bits;
    142 			break;
    143 
    144 		case '\0':
    145 		default:
    146 #ifdef SETMODE_DEBUG
    147 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    148 #endif
    149 			return (newmode);
    150 		}
    151 }
    152 
    153 #define	ADDCMD(a, b, c, d)						\
    154 	if (set >= endset) {						\
    155 		register BITCMD *newset;				\
    156 		setlen += SET_LEN_INCR;					\
    157 		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
    158 		if (!saveset)						\
    159 			return (NULL);					\
    160 		set = newset + (set - saveset);				\
    161 		saveset = newset;					\
    162 		endset = newset + (setlen - 2);				\
    163 	}								\
    164 	set = addcmd(set, (a), (b), (c), (d))
    165 
    166 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    167 
    168 void *
    169 setmode(p)
    170 	register char *p;
    171 {
    172 	register int perm, who;
    173 	register char op;
    174 	BITCMD *set, *saveset, *endset;
    175 	sigset_t sigset, sigoset;
    176 	mode_t mask;
    177 	int equalopdone, permXbits, setlen;
    178 
    179 	if (!*p)
    180 		return (NULL);
    181 
    182 	/*
    183 	 * Get a copy of the mask for the permissions that are mask relative.
    184 	 * Flip the bits, we want what's not set.  Since it's possible that
    185 	 * the caller is opening files inside a signal handler, protect them
    186 	 * as best we can.
    187 	 */
    188 	sigfillset(&sigset);
    189         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    190 	(void)umask(mask = umask(0));
    191 	mask = ~mask;
    192         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    193 
    194 	setlen = SET_LEN + 2;
    195 
    196 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    197 		return (NULL);
    198 	saveset = set;
    199 	endset = set + (setlen - 2);
    200 
    201 	/*
    202 	 * If an absolute number, get it and return; disallow non-octal digits
    203 	 * or illegal bits.
    204 	 */
    205 	if (isdigit(*p)) {
    206 		perm = (mode_t)strtol(p, NULL, 8);
    207 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    208 			free(saveset);
    209 			return (NULL);
    210 		}
    211 		while (*++p)
    212 			if (*p < '0' || *p > '7') {
    213 				free(saveset);
    214 				return (NULL);
    215 			}
    216 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    217 		return (saveset);
    218 	}
    219 
    220 	/*
    221 	 * Build list of structures to set/clear/copy bits as described by
    222 	 * each clause of the symbolic mode.
    223 	 */
    224 	for (;;) {
    225 		/* First, find out which bits might be modified. */
    226 		for (who = 0;; ++p) {
    227 			switch (*p) {
    228 			case 'a':
    229 				who |= STANDARD_BITS;
    230 				break;
    231 			case 'u':
    232 				who |= S_ISUID|S_IRWXU;
    233 				break;
    234 			case 'g':
    235 				who |= S_ISGID|S_IRWXG;
    236 				break;
    237 			case 'o':
    238 				who |= S_IRWXO;
    239 				break;
    240 			default:
    241 				goto getop;
    242 			}
    243 		}
    244 
    245 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    246 			free(saveset);
    247 			return (NULL);
    248 		}
    249 		if (op == '=')
    250 			equalopdone = 0;
    251 
    252 		who &= ~S_ISTXT;
    253 		for (perm = 0, permXbits = 0;; ++p) {
    254 			switch (*p) {
    255 			case 'r':
    256 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    257 				break;
    258 			case 's':
    259 				/* If only "other" bits ignore set-id. */
    260 				if (who & ~S_IRWXO)
    261 					perm |= S_ISUID|S_ISGID;
    262 				break;
    263 			case 't':
    264 				/* If only "other" bits ignore sticky. */
    265 				if (who & ~S_IRWXO) {
    266 					who |= S_ISTXT;
    267 					perm |= S_ISTXT;
    268 				}
    269 				break;
    270 			case 'w':
    271 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    272 				break;
    273 			case 'X':
    274 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    275 				break;
    276 			case 'x':
    277 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    278 				break;
    279 			case 'u':
    280 			case 'g':
    281 			case 'o':
    282 				/*
    283 				 * When ever we hit 'u', 'g', or 'o', we have
    284 				 * to flush out any partial mode that we have,
    285 				 * and then do the copying of the mode bits.
    286 				 */
    287 				if (perm) {
    288 					ADDCMD(op, who, perm, mask);
    289 					perm = 0;
    290 				}
    291 				if (op == '=')
    292 					equalopdone = 1;
    293 				if (op == '+' && permXbits) {
    294 					ADDCMD('X', who, permXbits, mask);
    295 					permXbits = 0;
    296 				}
    297 				ADDCMD(*p, who, op, mask);
    298 				break;
    299 
    300 			default:
    301 				/*
    302 				 * Add any permissions that we haven't already
    303 				 * done.
    304 				 */
    305 				if (perm || (op == '=' && !equalopdone)) {
    306 					if (op == '=')
    307 						equalopdone = 1;
    308 					ADDCMD(op, who, perm, mask);
    309 					perm = 0;
    310 				}
    311 				if (permXbits) {
    312 					ADDCMD('X', who, permXbits, mask);
    313 					permXbits = 0;
    314 				}
    315 				goto apply;
    316 			}
    317 		}
    318 
    319 apply:		if (!*p)
    320 			break;
    321 		if (*p != ',')
    322 			goto getop;
    323 		++p;
    324 	}
    325 	set->cmd = 0;
    326 #ifdef SETMODE_DEBUG
    327 	(void)printf("Before compress_mode()\n");
    328 	dumpmode(saveset);
    329 #endif
    330 	compress_mode(saveset);
    331 #ifdef SETMODE_DEBUG
    332 	(void)printf("After compress_mode()\n");
    333 	dumpmode(saveset);
    334 #endif
    335 	return (saveset);
    336 }
    337 
    338 static BITCMD *
    339 addcmd(set, op, who, oparg, mask)
    340 	BITCMD *set;
    341 	register int oparg, who;
    342 	register int op;
    343 	u_int mask;
    344 {
    345 	switch (op) {
    346 	case '=':
    347 		set->cmd = '-';
    348 		set->bits = who ? who : STANDARD_BITS;
    349 		set++;
    350 
    351 		op = '+';
    352 		/* FALLTHROUGH */
    353 	case '+':
    354 	case '-':
    355 	case 'X':
    356 		set->cmd = op;
    357 		set->bits = (who ? who : mask) & oparg;
    358 		break;
    359 
    360 	case 'u':
    361 	case 'g':
    362 	case 'o':
    363 		set->cmd = op;
    364 		if (who) {
    365 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    366 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    367 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    368 			set->bits = ~0;
    369 		} else {
    370 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    371 			set->bits = mask;
    372 		}
    373 
    374 		if (oparg == '+')
    375 			set->cmd2 |= CMD2_SET;
    376 		else if (oparg == '-')
    377 			set->cmd2 |= CMD2_CLR;
    378 		else if (oparg == '=')
    379 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    380 		break;
    381 	}
    382 	return (set + 1);
    383 }
    384 
    385 #ifdef SETMODE_DEBUG
    386 static void
    387 dumpmode(set)
    388 	register BITCMD *set;
    389 {
    390 	for (; set->cmd; ++set)
    391 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    392 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    393 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    394 		    set->cmd2 & CMD2_SET ? " SET" : "",
    395 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    396 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    397 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    398 }
    399 #endif
    400 
    401 /*
    402  * Given an array of bitcmd structures, compress by compacting consecutive
    403  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    404  * 'g' and 'o' commands continue to be separate.  They could probably be
    405  * compacted, but it's not worth the effort.
    406  */
    407 static int
    408 compress_mode(set)
    409 	register BITCMD *set;
    410 {
    411 	register BITCMD *nset;
    412 	register int setbits, clrbits, Xbits, op;
    413 
    414 	for (nset = set;;) {
    415 		/* Copy over any 'u', 'g' and 'o' commands. */
    416 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    417 			*set++ = *nset++;
    418 			if (!op)
    419 				return;
    420 		}
    421 
    422 		for (setbits = clrbits = Xbits = 0;; nset++) {
    423 			if ((op = nset->cmd) == '-') {
    424 				clrbits |= nset->bits;
    425 				setbits &= ~nset->bits;
    426 				Xbits &= ~nset->bits;
    427 			} else if (op == '+') {
    428 				setbits |= nset->bits;
    429 				clrbits &= ~nset->bits;
    430 				Xbits &= ~nset->bits;
    431 			} else if (op == 'X')
    432 				Xbits |= nset->bits & ~setbits;
    433 			else
    434 				break;
    435 		}
    436 		if (clrbits) {
    437 			set->cmd = '-';
    438 			set->cmd2 = 0;
    439 			set->bits = clrbits;
    440 			set++;
    441 		}
    442 		if (setbits) {
    443 			set->cmd = '+';
    444 			set->cmd2 = 0;
    445 			set->bits = setbits;
    446 			set++;
    447 		}
    448 		if (Xbits) {
    449 			set->cmd = 'X';
    450 			set->cmd2 = 0;
    451 			set->bits = Xbits;
    452 			set++;
    453 		}
    454 	}
    455 }
    456