kern_environment.c revision 148585 
1/*-
2 * Copyright (c) 1998 Michael Smith
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27/*
28 * The unified bootloader passes us a pointer to a preserved copy of
29 * bootstrap/kernel environment variables.  We convert them to a
30 * dynamic array of strings later when the VM subsystem is up.
31 *
32 * We make these available through the kenv(2) syscall for userland
33 * and through getenv()/freeenv() setenv() unsetenv() testenv() for
34 * the kernel.
35 */
36
37#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/sys/kern/kern_environment.c 148585 2005-07-31 10:28:35Z netchild $");
39
40#include "opt_mac.h"
41
42#include <sys/types.h>
43#include <sys/param.h>
44#include <sys/proc.h>
45#include <sys/queue.h>
46#include <sys/lock.h>
47#include <sys/mac.h>
48#include <sys/malloc.h>
49#include <sys/mutex.h>
50#include <sys/kernel.h>
51#include <sys/sx.h>
52#include <sys/systm.h>
53#include <sys/sysent.h>
54#include <sys/sysproto.h>
55#include <sys/libkern.h>
56#include <sys/kenv.h>
57
58static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
59
60#define KENV_SIZE	512	/* Maximum number of environment strings */
61
62/* pointer to the static environment */
63char		*kern_envp;
64static char	*kernenv_next(char *);
65
66/* dynamic environment variables */
67char		**kenvp;
68struct sx	kenv_lock;
69
70/*
71 * No need to protect this with a mutex
72 * since SYSINITS are single threaded.
73 */
74int	dynamic_kenv = 0;
75
76#define KENV_CHECK	if (!dynamic_kenv) \
77			    panic("%s: called before SI_SUB_KMEM", __func__)
78
79int
80kenv(td, uap)
81	struct thread *td;
82	struct kenv_args /* {
83		int what;
84		const char *name;
85		char *value;
86		int len;
87	} */ *uap;
88{
89	char *name, *value;
90	size_t len, done, needed;
91	int error, i;
92
93	KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = 0"));
94
95	error = 0;
96	if (uap->what == KENV_DUMP) {
97#ifdef MAC
98		error = mac_check_kenv_dump(td->td_ucred);
99		if (error)
100			return (error);
101#endif
102		done = needed = 0;
103		sx_slock(&kenv_lock);
104		for (i = 0; kenvp[i] != NULL; i++) {
105			len = strlen(kenvp[i]) + 1;
106			needed += len;
107			len = min(len, uap->len - done);
108			/*
109			 * If called with a NULL or insufficiently large
110			 * buffer, just keep computing the required size.
111			 */
112			if (uap->value != NULL && len > 0) {
113				error = copyout(kenvp[i], uap->value + done,
114				    len);
115				if (error)
116					break;
117				done += len;
118			}
119		}
120		sx_sunlock(&kenv_lock);
121		td->td_retval[0] = ((done == needed) ? 0 : needed);
122		return (error);
123	}
124
125	if ((uap->what == KENV_SET) ||
126	    (uap->what == KENV_UNSET)) {
127		error = suser(td);
128		if (error)
129			return (error);
130	}
131
132	name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
133
134	error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
135	if (error)
136		goto done;
137
138	switch (uap->what) {
139	case KENV_GET:
140#ifdef MAC
141		error = mac_check_kenv_get(td->td_ucred, name);
142		if (error)
143			goto done;
144#endif
145		value = getenv(name);
146		if (value == NULL) {
147			error = ENOENT;
148			goto done;
149		}
150		len = strlen(value) + 1;
151		if (len > uap->len)
152			len = uap->len;
153		error = copyout(value, uap->value, len);
154		freeenv(value);
155		if (error)
156			goto done;
157		td->td_retval[0] = len;
158		break;
159	case KENV_SET:
160		len = uap->len;
161		if (len < 1) {
162			error = EINVAL;
163			goto done;
164		}
165		if (len > KENV_MVALLEN)
166			len = KENV_MVALLEN;
167		value = malloc(len, M_TEMP, M_WAITOK);
168		error = copyinstr(uap->value, value, len, NULL);
169		if (error) {
170			free(value, M_TEMP);
171			goto done;
172		}
173#ifdef MAC
174		error = mac_check_kenv_set(td->td_ucred, name, value);
175		if (error == 0)
176#endif
177			setenv(name, value);
178		free(value, M_TEMP);
179		break;
180	case KENV_UNSET:
181#ifdef MAC
182		error = mac_check_kenv_unset(td->td_ucred, name);
183		if (error)
184			goto done;
185#endif
186		error = unsetenv(name);
187		if (error)
188			error = ENOENT;
189		break;
190	default:
191		error = EINVAL;
192		break;
193	}
194done:
195	free(name, M_TEMP);
196	return (error);
197}
198
199/*
200 * Setup the dynamic kernel environment.
201 */
202static void
203init_dynamic_kenv(void *data __unused)
204{
205	char *cp;
206	int len, i;
207
208	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
209		M_WAITOK | M_ZERO);
210	i = 0;
211	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
212		len = strlen(cp) + 1;
213		kenvp[i] = malloc(len, M_KENV, M_WAITOK);
214		strcpy(kenvp[i++], cp);
215	}
216	kenvp[i] = NULL;
217
218	sx_init(&kenv_lock, "kernel environment");
219	dynamic_kenv = 1;
220}
221SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
222
223void
224freeenv(char *env)
225{
226
227	if (dynamic_kenv)
228		free(env, M_KENV);
229}
230
231/*
232 * Internal functions for string lookup.
233 */
234static char *
235_getenv_dynamic(const char *name, int *idx)
236{
237	char *cp;
238	int len, i;
239
240	sx_assert(&kenv_lock, SX_LOCKED);
241	len = strlen(name);
242	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
243		if ((cp[len] == '=') &&
244		    (strncmp(cp, name, len) == 0)) {
245			if (idx != NULL)
246				*idx = i;
247			return (cp + len + 1);
248		}
249	}
250	return (NULL);
251}
252
253static char *
254_getenv_static(const char *name)
255{
256	char *cp, *ep;
257	int len;
258
259	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
260		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
261			;
262		if (*ep != '=')
263			continue;
264		len = ep - cp;
265		ep++;
266		if (!strncmp(name, cp, len) && name[len] == 0)
267			return (ep);
268	}
269	return (NULL);
270}
271
272/*
273 * Look up an environment variable by name.
274 * Return a pointer to the string if found.
275 * The pointer has to be freed with freeenv()
276 * after use.
277 */
278char *
279getenv(const char *name)
280{
281	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
282	char *ret, *cp;
283	int len;
284
285	if (dynamic_kenv) {
286		sx_slock(&kenv_lock);
287		cp = _getenv_dynamic(name, NULL);
288		if (cp != NULL) {
289			strcpy(buf, cp);
290			sx_sunlock(&kenv_lock);
291			len = strlen(buf) + 1;
292			ret = malloc(len, M_KENV, M_WAITOK);
293			strcpy(ret, buf);
294		} else {
295			sx_sunlock(&kenv_lock);
296			ret = NULL;
297		}
298	} else
299		ret = _getenv_static(name);
300	return (ret);
301}
302
303/*
304 * Test if an environment variable is defined.
305 */
306int
307testenv(const char *name)
308{
309	char *cp;
310
311	if (dynamic_kenv) {
312		sx_slock(&kenv_lock);
313		cp = _getenv_dynamic(name, NULL);
314		sx_sunlock(&kenv_lock);
315	} else
316		cp = _getenv_static(name);
317	if (cp != NULL)
318		return (1);
319	return (0);
320}
321
322/*
323 * Set an environment variable by name.
324 */
325int
326setenv(const char *name, const char *value)
327{
328	char *buf, *cp, *oldenv;
329	int namelen, vallen, i;
330
331	KENV_CHECK;
332
333	namelen = strlen(name) + 1;
334	if (namelen > KENV_MNAMELEN)
335		return (-1);
336	vallen = strlen(value) + 1;
337	if (vallen > KENV_MVALLEN)
338		return (-1);
339	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
340	sprintf(buf, "%s=%s", name, value);
341
342	sx_xlock(&kenv_lock);
343	cp = _getenv_dynamic(name, &i);
344	if (cp != NULL) {
345		oldenv = kenvp[i];
346		kenvp[i] = buf;
347		sx_xunlock(&kenv_lock);
348		free(oldenv, M_KENV);
349	} else {
350		/* We add the option if it wasn't found */
351		for (i = 0; (cp = kenvp[i]) != NULL; i++)
352			;
353
354		/* Bounds checking */
355		if (i < 0 || i >= KENV_SIZE) {
356			free(buf, M_KENV);
357			sx_xunlock(&kenv_lock);
358			return (-1);
359		}
360
361		kenvp[i] = buf;
362		kenvp[i + 1] = NULL;
363		sx_xunlock(&kenv_lock);
364	}
365	return (0);
366}
367
368/*
369 * Unset an environment variable string.
370 */
371int
372unsetenv(const char *name)
373{
374	char *cp, *oldenv;
375	int i, j;
376
377	KENV_CHECK;
378
379	sx_xlock(&kenv_lock);
380	cp = _getenv_dynamic(name, &i);
381	if (cp != NULL) {
382		oldenv = kenvp[i];
383		for (j = i + 1; kenvp[j] != NULL; j++)
384			kenvp[i++] = kenvp[j];
385		kenvp[i] = NULL;
386		sx_xunlock(&kenv_lock);
387		free(oldenv, M_KENV);
388		return (0);
389	}
390	sx_xunlock(&kenv_lock);
391	return (-1);
392}
393
394/*
395 * Return a string value from an environment variable.
396 */
397int
398getenv_string(const char *name, char *data, int size)
399{
400	char *tmp;
401
402	tmp = getenv(name);
403	if (tmp != NULL) {
404		strlcpy(data, tmp, size);
405		freeenv(tmp);
406		return (1);
407	} else
408		return (0);
409}
410
411/*
412 * Return an integer value from an environment variable.
413 */
414int
415getenv_int(const char *name, int *data)
416{
417	quad_t tmp;
418	int rval;
419
420	rval = getenv_quad(name, &tmp);
421	if (rval)
422		*data = (int) tmp;
423	return (rval);
424}
425
426/*
427 * Return a long value from an environment variable.
428 */
429long
430getenv_long(const char *name, long *data)
431{
432	quad_t tmp;
433	long rval;
434
435	rval = getenv_quad(name, &tmp);
436	if (rval)
437		*data = (long) tmp;
438	return (rval);
439}
440
441/*
442 * Return an unsigned long value from an environment variable.
443 */
444unsigned long
445getenv_ulong(const char *name, unsigned long *data)
446{
447	quad_t tmp;
448	long rval;
449
450	rval = getenv_quad(name, &tmp);
451	if (rval)
452		*data = (unsigned long) tmp;
453	return (rval);
454}
455
456/*
457 * Return a quad_t value from an environment variable.
458 */
459int
460getenv_quad(const char *name, quad_t *data)
461{
462	char	*value;
463	char	*vtp;
464	quad_t	iv;
465
466	value = getenv(name);
467	if (value == NULL)
468		return (0);
469	iv = strtoq(value, &vtp, 0);
470	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
471		freeenv(value);
472		return (0);
473	}
474	switch (vtp[0]) {
475	case 't': case 'T':
476		iv *= 1024;
477	case 'g': case 'G':
478		iv *= 1024;
479	case 'm': case 'M':
480		iv *= 1024;
481	case 'k': case 'K':
482		iv *= 1024;
483	case '\0':
484		break;
485	default:
486		freeenv(value);
487		return (0);
488	}
489	*data = iv;
490	freeenv(value);
491	return (1);
492}
493
494/*
495 * Find the next entry after the one which (cp) falls within, return a
496 * pointer to its start or NULL if there are no more.
497 */
498static char *
499kernenv_next(char *cp)
500{
501
502	if (cp != NULL) {
503		while (*cp != 0)
504			cp++;
505		cp++;
506		if (*cp == 0)
507			cp = NULL;
508	}
509	return (cp);
510}
511
512void
513tunable_int_init(void *data)
514{
515	struct tunable_int *d = (struct tunable_int *)data;
516
517	TUNABLE_INT_FETCH(d->path, d->var);
518}
519
520void
521tunable_long_init(void *data)
522{
523	struct tunable_long *d = (struct tunable_long *)data;
524
525	TUNABLE_LONG_FETCH(d->path, d->var);
526}
527
528void
529tunable_ulong_init(void *data)
530{
531	struct tunable_ulong *d = (struct tunable_ulong *)data;
532
533	TUNABLE_ULONG_FETCH(d->path, d->var);
534}
535
536void
537tunable_str_init(void *data)
538{
539	struct tunable_str *d = (struct tunable_str *)data;
540
541	TUNABLE_STR_FETCH(d->path, d->var, d->size);
542}
543