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 * 4. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)setmode.c	8.2 (Berkeley) 3/25/94";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include "namespace.h"
40#include <sys/types.h>
41#include <sys/stat.h>
42
43#include <ctype.h>
44#include <signal.h>
45#include <stddef.h>
46#include <stdlib.h>
47#include <unistd.h>
48
49#ifdef SETMODE_DEBUG
50#include <stdio.h>
51#endif
52#include "un-namespace.h"
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
57typedef 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
69static BITCMD	*addcmd(BITCMD *, int, int, int, u_int);
70static void	 compress_mode(BITCMD *);
71#ifdef SETMODE_DEBUG
72static void	 dumpmode(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 */
81mode_t
82getmode(const void *bbox, mode_t omode)
83{
84	const BITCMD *set;
85	mode_t clrval, newmode, value;
86
87	set = (const BITCMD *)bbox;
88	newmode = omode;
89	for (value = 0;; set++)
90		switch(set->cmd) {
91		/*
92		 * When copying the user, group or other bits around, we "know"
93		 * where the bits are in the mode so that we can do shifts to
94		 * copy them around.  If we don't use shifts, it gets real
95		 * grundgy with lots of single bit checks and bit sets.
96		 */
97		case 'u':
98			value = (newmode & S_IRWXU) >> 6;
99			goto common;
100
101		case 'g':
102			value = (newmode & S_IRWXG) >> 3;
103			goto common;
104
105		case 'o':
106			value = newmode & S_IRWXO;
107common:			if (set->cmd2 & CMD2_CLR) {
108				clrval =
109				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
110				if (set->cmd2 & CMD2_UBITS)
111					newmode &= ~((clrval<<6) & set->bits);
112				if (set->cmd2 & CMD2_GBITS)
113					newmode &= ~((clrval<<3) & set->bits);
114				if (set->cmd2 & CMD2_OBITS)
115					newmode &= ~(clrval & set->bits);
116			}
117			if (set->cmd2 & CMD2_SET) {
118				if (set->cmd2 & CMD2_UBITS)
119					newmode |= (value<<6) & set->bits;
120				if (set->cmd2 & CMD2_GBITS)
121					newmode |= (value<<3) & set->bits;
122				if (set->cmd2 & CMD2_OBITS)
123					newmode |= value & set->bits;
124			}
125			break;
126
127		case '+':
128			newmode |= set->bits;
129			break;
130
131		case '-':
132			newmode &= ~set->bits;
133			break;
134
135		case 'X':
136			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
137				newmode |= set->bits;
138			break;
139
140		case '\0':
141		default:
142#ifdef SETMODE_DEBUG
143			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
144#endif
145			return (newmode);
146		}
147}
148
149#define	ADDCMD(a, b, c, d)						\
150	if (set >= endset) {						\
151		BITCMD *newset;						\
152		setlen += SET_LEN_INCR;					\
153		newset = realloc(saveset, sizeof(BITCMD) * setlen);	\
154		if (!newset) {						\
155			if (saveset)					\
156				free(saveset);				\
157			saveset = NULL;					\
158			return (NULL);					\
159		}							\
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
168void *
169setmode(const char *p)
170{
171	int perm, who;
172	char op, *ep;
173	BITCMD *set, *saveset, *endset;
174	sigset_t sigset, sigoset;
175	mode_t mask;
176	int equalopdone=0, permXbits, setlen;
177	long perml;
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((unsigned char)*p)) {
206		perml = strtol(p, &ep, 8);
207		if (*ep || perml < 0 || perml & ~(STANDARD_BITS|S_ISTXT)) {
208			free(saveset);
209			return (NULL);
210		}
211		perm = (mode_t)perml;
212		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
213		set->cmd = 0;
214		return (saveset);
215	}
216
217	/*
218	 * Build list of structures to set/clear/copy bits as described by
219	 * each clause of the symbolic mode.
220	 */
221	for (;;) {
222		/* First, find out which bits might be modified. */
223		for (who = 0;; ++p) {
224			switch (*p) {
225			case 'a':
226				who |= STANDARD_BITS;
227				break;
228			case 'u':
229				who |= S_ISUID|S_IRWXU;
230				break;
231			case 'g':
232				who |= S_ISGID|S_IRWXG;
233				break;
234			case 'o':
235				who |= S_IRWXO;
236				break;
237			default:
238				goto getop;
239			}
240		}
241
242getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
243			free(saveset);
244			return (NULL);
245		}
246		if (op == '=')
247			equalopdone = 0;
248
249		who &= ~S_ISTXT;
250		for (perm = 0, permXbits = 0;; ++p) {
251			switch (*p) {
252			case 'r':
253				perm |= S_IRUSR|S_IRGRP|S_IROTH;
254				break;
255			case 's':
256				/* If only "other" bits ignore set-id. */
257				if (!who || who & ~S_IRWXO)
258					perm |= S_ISUID|S_ISGID;
259				break;
260			case 't':
261				/* If only "other" bits ignore sticky. */
262				if (!who || who & ~S_IRWXO) {
263					who |= S_ISTXT;
264					perm |= S_ISTXT;
265				}
266				break;
267			case 'w':
268				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
269				break;
270			case 'X':
271				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
272				break;
273			case 'x':
274				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
275				break;
276			case 'u':
277			case 'g':
278			case 'o':
279				/*
280				 * When ever we hit 'u', 'g', or 'o', we have
281				 * to flush out any partial mode that we have,
282				 * and then do the copying of the mode bits.
283				 */
284				if (perm) {
285					ADDCMD(op, who, perm, mask);
286					perm = 0;
287				}
288				if (op == '=')
289					equalopdone = 1;
290				if (op == '+' && permXbits) {
291					ADDCMD('X', who, permXbits, mask);
292					permXbits = 0;
293				}
294				ADDCMD(*p, who, op, mask);
295				break;
296
297			default:
298				/*
299				 * Add any permissions that we haven't already
300				 * done.
301				 */
302				if (perm || (op == '=' && !equalopdone)) {
303					if (op == '=')
304						equalopdone = 1;
305					ADDCMD(op, who, perm, mask);
306					perm = 0;
307				}
308				if (permXbits) {
309					ADDCMD('X', who, permXbits, mask);
310					permXbits = 0;
311				}
312				goto apply;
313			}
314		}
315
316apply:		if (!*p)
317			break;
318		if (*p != ',')
319			goto getop;
320		++p;
321	}
322	set->cmd = 0;
323#ifdef SETMODE_DEBUG
324	(void)printf("Before compress_mode()\n");
325	dumpmode(saveset);
326#endif
327	compress_mode(saveset);
328#ifdef SETMODE_DEBUG
329	(void)printf("After compress_mode()\n");
330	dumpmode(saveset);
331#endif
332	return (saveset);
333}
334
335static BITCMD *
336addcmd(BITCMD *set, int op, int who, int oparg, u_int mask)
337{
338	switch (op) {
339	case '=':
340		set->cmd = '-';
341		set->bits = who ? who : STANDARD_BITS;
342		set++;
343
344		op = '+';
345		/* FALLTHROUGH */
346	case '+':
347	case '-':
348	case 'X':
349		set->cmd = op;
350		set->bits = (who ? who : mask) & oparg;
351		break;
352
353	case 'u':
354	case 'g':
355	case 'o':
356		set->cmd = op;
357		if (who) {
358			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
359				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
360				    ((who & S_IROTH) ? CMD2_OBITS : 0);
361			set->bits = (mode_t)~0;
362		} else {
363			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
364			set->bits = mask;
365		}
366
367		if (oparg == '+')
368			set->cmd2 |= CMD2_SET;
369		else if (oparg == '-')
370			set->cmd2 |= CMD2_CLR;
371		else if (oparg == '=')
372			set->cmd2 |= CMD2_SET|CMD2_CLR;
373		break;
374	}
375	return (set + 1);
376}
377
378#ifdef SETMODE_DEBUG
379static void
380dumpmode(BITCMD *set)
381{
382	for (; set->cmd; ++set)
383		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
384		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
385		    set->cmd2 & CMD2_CLR ? " CLR" : "",
386		    set->cmd2 & CMD2_SET ? " SET" : "",
387		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
388		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
389		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
390}
391#endif
392
393/*
394 * Given an array of bitcmd structures, compress by compacting consecutive
395 * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
396 * 'g' and 'o' commands continue to be separate.  They could probably be
397 * compacted, but it's not worth the effort.
398 */
399static void
400compress_mode(BITCMD *set)
401{
402	BITCMD *nset;
403	int setbits, clrbits, Xbits, op;
404
405	for (nset = set;;) {
406		/* Copy over any 'u', 'g' and 'o' commands. */
407		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
408			*set++ = *nset++;
409			if (!op)
410				return;
411		}
412
413		for (setbits = clrbits = Xbits = 0;; nset++) {
414			if ((op = nset->cmd) == '-') {
415				clrbits |= nset->bits;
416				setbits &= ~nset->bits;
417				Xbits &= ~nset->bits;
418			} else if (op == '+') {
419				setbits |= nset->bits;
420				clrbits &= ~nset->bits;
421				Xbits &= ~nset->bits;
422			} else if (op == 'X')
423				Xbits |= nset->bits & ~setbits;
424			else
425				break;
426		}
427		if (clrbits) {
428			set->cmd = '-';
429			set->cmd2 = 0;
430			set->bits = clrbits;
431			set++;
432		}
433		if (setbits) {
434			set->cmd = '+';
435			set->cmd2 = 0;
436			set->bits = setbits;
437			set++;
438		}
439		if (Xbits) {
440			set->cmd = 'X';
441			set->cmd2 = 0;
442			set->bits = Xbits;
443			set++;
444		}
445	}
446}
447