kern_environment.c revision 180661 
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 180661 2008-07-21 15:05:25Z pjd $");
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/malloc.h>
48#include <sys/mutex.h>
49#include <sys/priv.h>
50#include <sys/kernel.h>
51#include <sys/systm.h>
52#include <sys/sysent.h>
53#include <sys/sysproto.h>
54#include <sys/libkern.h>
55#include <sys/kenv.h>
56
57#include <security/mac/mac_framework.h>
58
59static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
60
61#define KENV_SIZE	512	/* Maximum number of environment strings */
62
63/* pointer to the static environment */
64char		*kern_envp;
65static char	*kernenv_next(char *);
66
67/* dynamic environment variables */
68char		**kenvp;
69struct mtx	kenv_lock;
70
71/*
72 * No need to protect this with a mutex 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, *buffer = NULL;
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_kenv_check_dump(td->td_ucred);
99		if (error)
100			return (error);
101#endif
102		done = needed = 0;
103		if (uap->len > 0 && uap->value != NULL)
104			buffer = malloc(uap->len, M_TEMP, M_WAITOK|M_ZERO);
105		mtx_lock(&kenv_lock);
106		for (i = 0; kenvp[i] != NULL; i++) {
107			len = strlen(kenvp[i]) + 1;
108			needed += len;
109			len = min(len, uap->len - done);
110			/*
111			 * If called with a NULL or insufficiently large
112			 * buffer, just keep computing the required size.
113			 */
114			if (uap->value != NULL && buffer != NULL && len > 0) {
115				bcopy(kenvp[i], buffer + done, len);
116				done += len;
117			}
118		}
119		mtx_unlock(&kenv_lock);
120		if (buffer != NULL) {
121			error = copyout(buffer, uap->value, done);
122			free(buffer, M_TEMP);
123		}
124		td->td_retval[0] = ((done == needed) ? 0 : needed);
125		return (error);
126	}
127
128	switch (uap->what) {
129	case KENV_SET:
130		error = priv_check(td, PRIV_KENV_SET);
131		if (error)
132			return (error);
133		break;
134
135	case KENV_UNSET:
136		error = priv_check(td, PRIV_KENV_UNSET);
137		if (error)
138			return (error);
139		break;
140	}
141
142	name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
143
144	error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
145	if (error)
146		goto done;
147
148	switch (uap->what) {
149	case KENV_GET:
150#ifdef MAC
151		error = mac_kenv_check_get(td->td_ucred, name);
152		if (error)
153			goto done;
154#endif
155		value = getenv(name);
156		if (value == NULL) {
157			error = ENOENT;
158			goto done;
159		}
160		len = strlen(value) + 1;
161		if (len > uap->len)
162			len = uap->len;
163		error = copyout(value, uap->value, len);
164		freeenv(value);
165		if (error)
166			goto done;
167		td->td_retval[0] = len;
168		break;
169	case KENV_SET:
170		len = uap->len;
171		if (len < 1) {
172			error = EINVAL;
173			goto done;
174		}
175		if (len > KENV_MVALLEN)
176			len = KENV_MVALLEN;
177		value = malloc(len, M_TEMP, M_WAITOK);
178		error = copyinstr(uap->value, value, len, NULL);
179		if (error) {
180			free(value, M_TEMP);
181			goto done;
182		}
183#ifdef MAC
184		error = mac_kenv_check_set(td->td_ucred, name, value);
185		if (error == 0)
186#endif
187			setenv(name, value);
188		free(value, M_TEMP);
189		break;
190	case KENV_UNSET:
191#ifdef MAC
192		error = mac_kenv_check_unset(td->td_ucred, name);
193		if (error)
194			goto done;
195#endif
196		error = unsetenv(name);
197		if (error)
198			error = ENOENT;
199		break;
200	default:
201		error = EINVAL;
202		break;
203	}
204done:
205	free(name, M_TEMP);
206	return (error);
207}
208
209/*
210 * Setup the dynamic kernel environment.
211 */
212static void
213init_dynamic_kenv(void *data __unused)
214{
215	char *cp;
216	int len, i;
217
218	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
219		M_WAITOK | M_ZERO);
220	i = 0;
221	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
222		len = strlen(cp) + 1;
223		if (i < KENV_SIZE) {
224			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
225			strcpy(kenvp[i++], cp);
226		} else
227			printf(
228			    "WARNING: too many kenv strings, ignoring %s\n",
229			    cp);
230	}
231	kenvp[i] = NULL;
232
233	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
234	dynamic_kenv = 1;
235}
236SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
237
238void
239freeenv(char *env)
240{
241
242	if (dynamic_kenv)
243		free(env, M_KENV);
244}
245
246/*
247 * Internal functions for string lookup.
248 */
249static char *
250_getenv_dynamic(const char *name, int *idx)
251{
252	char *cp;
253	int len, i;
254
255	mtx_assert(&kenv_lock, MA_OWNED);
256	len = strlen(name);
257	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
258		if ((strncmp(cp, name, len) == 0) &&
259		    (cp[len] == '=')) {
260			if (idx != NULL)
261				*idx = i;
262			return (cp + len + 1);
263		}
264	}
265	return (NULL);
266}
267
268static char *
269_getenv_static(const char *name)
270{
271	char *cp, *ep;
272	int len;
273
274	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
275		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
276			;
277		if (*ep != '=')
278			continue;
279		len = ep - cp;
280		ep++;
281		if (!strncmp(name, cp, len) && name[len] == 0)
282			return (ep);
283	}
284	return (NULL);
285}
286
287/*
288 * Look up an environment variable by name.
289 * Return a pointer to the string if found.
290 * The pointer has to be freed with freeenv()
291 * after use.
292 */
293char *
294getenv(const char *name)
295{
296	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
297	char *ret, *cp;
298	int len;
299
300	if (dynamic_kenv) {
301		mtx_lock(&kenv_lock);
302		cp = _getenv_dynamic(name, NULL);
303		if (cp != NULL) {
304			strcpy(buf, cp);
305			mtx_unlock(&kenv_lock);
306			len = strlen(buf) + 1;
307			ret = malloc(len, M_KENV, M_WAITOK);
308			strcpy(ret, buf);
309		} else {
310			mtx_unlock(&kenv_lock);
311			ret = NULL;
312		}
313	} else
314		ret = _getenv_static(name);
315	return (ret);
316}
317
318/*
319 * Test if an environment variable is defined.
320 */
321int
322testenv(const char *name)
323{
324	char *cp;
325
326	if (dynamic_kenv) {
327		mtx_lock(&kenv_lock);
328		cp = _getenv_dynamic(name, NULL);
329		mtx_unlock(&kenv_lock);
330	} else
331		cp = _getenv_static(name);
332	if (cp != NULL)
333		return (1);
334	return (0);
335}
336
337/*
338 * Set an environment variable by name.
339 */
340int
341setenv(const char *name, const char *value)
342{
343	char *buf, *cp, *oldenv;
344	int namelen, vallen, i;
345
346	KENV_CHECK;
347
348	namelen = strlen(name) + 1;
349	if (namelen > KENV_MNAMELEN)
350		return (-1);
351	vallen = strlen(value) + 1;
352	if (vallen > KENV_MVALLEN)
353		return (-1);
354	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
355	sprintf(buf, "%s=%s", name, value);
356
357	mtx_lock(&kenv_lock);
358	cp = _getenv_dynamic(name, &i);
359	if (cp != NULL) {
360		oldenv = kenvp[i];
361		kenvp[i] = buf;
362		mtx_unlock(&kenv_lock);
363		free(oldenv, M_KENV);
364	} else {
365		/* We add the option if it wasn't found */
366		for (i = 0; (cp = kenvp[i]) != NULL; i++)
367			;
368
369		/* Bounds checking */
370		if (i < 0 || i >= KENV_SIZE) {
371			free(buf, M_KENV);
372			mtx_unlock(&kenv_lock);
373			return (-1);
374		}
375
376		kenvp[i] = buf;
377		kenvp[i + 1] = NULL;
378		mtx_unlock(&kenv_lock);
379	}
380	return (0);
381}
382
383/*
384 * Unset an environment variable string.
385 */
386int
387unsetenv(const char *name)
388{
389	char *cp, *oldenv;
390	int i, j;
391
392	KENV_CHECK;
393
394	mtx_lock(&kenv_lock);
395	cp = _getenv_dynamic(name, &i);
396	if (cp != NULL) {
397		oldenv = kenvp[i];
398		for (j = i + 1; kenvp[j] != NULL; j++)
399			kenvp[i++] = kenvp[j];
400		kenvp[i] = NULL;
401		mtx_unlock(&kenv_lock);
402		free(oldenv, M_KENV);
403		return (0);
404	}
405	mtx_unlock(&kenv_lock);
406	return (-1);
407}
408
409/*
410 * Return a string value from an environment variable.
411 */
412int
413getenv_string(const char *name, char *data, int size)
414{
415	char *tmp;
416
417	tmp = getenv(name);
418	if (tmp != NULL) {
419		strlcpy(data, tmp, size);
420		freeenv(tmp);
421		return (1);
422	} else
423		return (0);
424}
425
426/*
427 * Return an integer value from an environment variable.
428 */
429int
430getenv_int(const char *name, int *data)
431{
432	quad_t tmp;
433	int rval;
434
435	rval = getenv_quad(name, &tmp);
436	if (rval)
437		*data = (int) tmp;
438	return (rval);
439}
440
441/*
442 * Return an unsigned integer value from an environment variable.
443 */
444int
445getenv_uint(const char *name, unsigned int *data)
446{
447	quad_t tmp;
448	int rval;
449
450	rval = getenv_quad(name, &tmp);
451	if (rval)
452		*data = (unsigned int) tmp;
453	return (rval);
454}
455
456/*
457 * Return a long value from an environment variable.
458 */
459int
460getenv_long(const char *name, long *data)
461{
462	quad_t tmp;
463	int rval;
464
465	rval = getenv_quad(name, &tmp);
466	if (rval)
467		*data = (long) tmp;
468	return (rval);
469}
470
471/*
472 * Return an unsigned long value from an environment variable.
473 */
474int
475getenv_ulong(const char *name, unsigned long *data)
476{
477	quad_t tmp;
478	int rval;
479
480	rval = getenv_quad(name, &tmp);
481	if (rval)
482		*data = (unsigned long) tmp;
483	return (rval);
484}
485
486/*
487 * Return a quad_t value from an environment variable.
488 */
489int
490getenv_quad(const char *name, quad_t *data)
491{
492	char	*value;
493	char	*vtp;
494	quad_t	iv;
495
496	value = getenv(name);
497	if (value == NULL)
498		return (0);
499	iv = strtoq(value, &vtp, 0);
500	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
501		freeenv(value);
502		return (0);
503	}
504	switch (vtp[0]) {
505	case 't': case 'T':
506		iv *= 1024;
507	case 'g': case 'G':
508		iv *= 1024;
509	case 'm': case 'M':
510		iv *= 1024;
511	case 'k': case 'K':
512		iv *= 1024;
513	case '\0':
514		break;
515	default:
516		freeenv(value);
517		return (0);
518	}
519	*data = iv;
520	freeenv(value);
521	return (1);
522}
523
524/*
525 * Find the next entry after the one which (cp) falls within, return a
526 * pointer to its start or NULL if there are no more.
527 */
528static char *
529kernenv_next(char *cp)
530{
531
532	if (cp != NULL) {
533		while (*cp != 0)
534			cp++;
535		cp++;
536		if (*cp == 0)
537			cp = NULL;
538	}
539	return (cp);
540}
541
542void
543tunable_int_init(void *data)
544{
545	struct tunable_int *d = (struct tunable_int *)data;
546
547	TUNABLE_INT_FETCH(d->path, d->var);
548}
549
550void
551tunable_long_init(void *data)
552{
553	struct tunable_long *d = (struct tunable_long *)data;
554
555	TUNABLE_LONG_FETCH(d->path, d->var);
556}
557
558void
559tunable_ulong_init(void *data)
560{
561	struct tunable_ulong *d = (struct tunable_ulong *)data;
562
563	TUNABLE_ULONG_FETCH(d->path, d->var);
564}
565
566void
567tunable_quad_init(void *data)
568{
569	struct tunable_quad *d = (struct tunable_quad *)data;
570
571	TUNABLE_QUAD_FETCH(d->path, d->var);
572}
573
574void
575tunable_str_init(void *data)
576{
577	struct tunable_str *d = (struct tunable_str *)data;
578
579	TUNABLE_STR_FETCH(d->path, d->var, d->size);
580}
581