kern_environment.c revision 221607 
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 221607 2011-05-07 17:59:07Z jh $");
39
40#include <sys/types.h>
41#include <sys/param.h>
42#include <sys/proc.h>
43#include <sys/queue.h>
44#include <sys/lock.h>
45#include <sys/malloc.h>
46#include <sys/mutex.h>
47#include <sys/priv.h>
48#include <sys/kernel.h>
49#include <sys/systm.h>
50#include <sys/sysent.h>
51#include <sys/sysproto.h>
52#include <sys/libkern.h>
53#include <sys/kenv.h>
54
55#include <security/mac/mac_framework.h>
56
57static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
58
59#define KENV_SIZE	512	/* Maximum number of environment strings */
60
61/* pointer to the static environment */
62char		*kern_envp;
63static int	env_len;
64static int	env_pos;
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, buflen;
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		buflen = uap->len;
104		if (buflen > KENV_SIZE * (KENV_MNAMELEN + KENV_MVALLEN + 2))
105			buflen = KENV_SIZE * (KENV_MNAMELEN +
106			    KENV_MVALLEN + 2);
107		if (uap->len > 0 && uap->value != NULL)
108			buffer = malloc(buflen, M_TEMP, M_WAITOK|M_ZERO);
109		mtx_lock(&kenv_lock);
110		for (i = 0; kenvp[i] != NULL; i++) {
111			len = strlen(kenvp[i]) + 1;
112			needed += len;
113			len = min(len, buflen - done);
114			/*
115			 * If called with a NULL or insufficiently large
116			 * buffer, just keep computing the required size.
117			 */
118			if (uap->value != NULL && buffer != NULL && len > 0) {
119				bcopy(kenvp[i], buffer + done, len);
120				done += len;
121			}
122		}
123		mtx_unlock(&kenv_lock);
124		if (buffer != NULL) {
125			error = copyout(buffer, uap->value, done);
126			free(buffer, M_TEMP);
127		}
128		td->td_retval[0] = ((done == needed) ? 0 : needed);
129		return (error);
130	}
131
132	switch (uap->what) {
133	case KENV_SET:
134		error = priv_check(td, PRIV_KENV_SET);
135		if (error)
136			return (error);
137		break;
138
139	case KENV_UNSET:
140		error = priv_check(td, PRIV_KENV_UNSET);
141		if (error)
142			return (error);
143		break;
144	}
145
146	name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
147
148	error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
149	if (error)
150		goto done;
151
152	switch (uap->what) {
153	case KENV_GET:
154#ifdef MAC
155		error = mac_kenv_check_get(td->td_ucred, name);
156		if (error)
157			goto done;
158#endif
159		value = getenv(name);
160		if (value == NULL) {
161			error = ENOENT;
162			goto done;
163		}
164		len = strlen(value) + 1;
165		if (len > uap->len)
166			len = uap->len;
167		error = copyout(value, uap->value, len);
168		freeenv(value);
169		if (error)
170			goto done;
171		td->td_retval[0] = len;
172		break;
173	case KENV_SET:
174		len = uap->len;
175		if (len < 1) {
176			error = EINVAL;
177			goto done;
178		}
179		if (len > KENV_MVALLEN)
180			len = KENV_MVALLEN;
181		value = malloc(len, M_TEMP, M_WAITOK);
182		error = copyinstr(uap->value, value, len, NULL);
183		if (error) {
184			free(value, M_TEMP);
185			goto done;
186		}
187#ifdef MAC
188		error = mac_kenv_check_set(td->td_ucred, name, value);
189		if (error == 0)
190#endif
191			setenv(name, value);
192		free(value, M_TEMP);
193		break;
194	case KENV_UNSET:
195#ifdef MAC
196		error = mac_kenv_check_unset(td->td_ucred, name);
197		if (error)
198			goto done;
199#endif
200		error = unsetenv(name);
201		if (error)
202			error = ENOENT;
203		break;
204	default:
205		error = EINVAL;
206		break;
207	}
208done:
209	free(name, M_TEMP);
210	return (error);
211}
212
213void
214init_static_kenv(char *buf, size_t len)
215{
216	kern_envp = buf;
217	env_len = len;
218	env_pos = 0;
219}
220
221/*
222 * Setup the dynamic kernel environment.
223 */
224static void
225init_dynamic_kenv(void *data __unused)
226{
227	char *cp;
228	int len, i;
229
230	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
231		M_WAITOK | M_ZERO);
232	i = 0;
233	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
234		len = strlen(cp) + 1;
235		if (i < KENV_SIZE) {
236			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
237			strcpy(kenvp[i++], cp);
238		} else
239			printf(
240			    "WARNING: too many kenv strings, ignoring %s\n",
241			    cp);
242	}
243	kenvp[i] = NULL;
244
245	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
246	dynamic_kenv = 1;
247}
248SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
249
250void
251freeenv(char *env)
252{
253
254	if (dynamic_kenv)
255		free(env, M_KENV);
256}
257
258/*
259 * Internal functions for string lookup.
260 */
261static char *
262_getenv_dynamic(const char *name, int *idx)
263{
264	char *cp;
265	int len, i;
266
267	mtx_assert(&kenv_lock, MA_OWNED);
268	len = strlen(name);
269	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
270		if ((strncmp(cp, name, len) == 0) &&
271		    (cp[len] == '=')) {
272			if (idx != NULL)
273				*idx = i;
274			return (cp + len + 1);
275		}
276	}
277	return (NULL);
278}
279
280static char *
281_getenv_static(const char *name)
282{
283	char *cp, *ep;
284	int len;
285
286	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
287		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
288			;
289		if (*ep != '=')
290			continue;
291		len = ep - cp;
292		ep++;
293		if (!strncmp(name, cp, len) && name[len] == 0)
294			return (ep);
295	}
296	return (NULL);
297}
298
299/*
300 * Look up an environment variable by name.
301 * Return a pointer to the string if found.
302 * The pointer has to be freed with freeenv()
303 * after use.
304 */
305char *
306getenv(const char *name)
307{
308	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
309	char *ret, *cp;
310	int len;
311
312	if (dynamic_kenv) {
313		mtx_lock(&kenv_lock);
314		cp = _getenv_dynamic(name, NULL);
315		if (cp != NULL) {
316			strcpy(buf, cp);
317			mtx_unlock(&kenv_lock);
318			len = strlen(buf) + 1;
319			ret = malloc(len, M_KENV, M_WAITOK);
320			strcpy(ret, buf);
321		} else {
322			mtx_unlock(&kenv_lock);
323			ret = NULL;
324			WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
325			    "getenv");
326		}
327	} else
328		ret = _getenv_static(name);
329	return (ret);
330}
331
332/*
333 * Test if an environment variable is defined.
334 */
335int
336testenv(const char *name)
337{
338	char *cp;
339
340	if (dynamic_kenv) {
341		mtx_lock(&kenv_lock);
342		cp = _getenv_dynamic(name, NULL);
343		mtx_unlock(&kenv_lock);
344	} else
345		cp = _getenv_static(name);
346	if (cp != NULL)
347		return (1);
348	return (0);
349}
350
351static int
352setenv_static(const char *name, const char *value)
353{
354	int len;
355
356	if (env_pos >= env_len)
357		return (-1);
358
359	/* Check space for x=y and two nuls */
360	len = strlen(name) + strlen(value);
361	if (len + 3 < env_len - env_pos) {
362		len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
363		env_pos += len+1;
364		kern_envp[env_pos] = '\0';
365		return (0);
366	} else
367		return (-1);
368
369}
370
371/*
372 * Set an environment variable by name.
373 */
374int
375setenv(const char *name, const char *value)
376{
377	char *buf, *cp, *oldenv;
378	int namelen, vallen, i;
379
380	if (dynamic_kenv == 0 && env_len > 0)
381		return (setenv_static(name, value));
382
383	KENV_CHECK;
384
385	namelen = strlen(name) + 1;
386	if (namelen > KENV_MNAMELEN)
387		return (-1);
388	vallen = strlen(value) + 1;
389	if (vallen > KENV_MVALLEN)
390		return (-1);
391	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
392	sprintf(buf, "%s=%s", name, value);
393
394	mtx_lock(&kenv_lock);
395	cp = _getenv_dynamic(name, &i);
396	if (cp != NULL) {
397		oldenv = kenvp[i];
398		kenvp[i] = buf;
399		mtx_unlock(&kenv_lock);
400		free(oldenv, M_KENV);
401	} else {
402		/* We add the option if it wasn't found */
403		for (i = 0; (cp = kenvp[i]) != NULL; i++)
404			;
405
406		/* Bounds checking */
407		if (i < 0 || i >= KENV_SIZE) {
408			free(buf, M_KENV);
409			mtx_unlock(&kenv_lock);
410			return (-1);
411		}
412
413		kenvp[i] = buf;
414		kenvp[i + 1] = NULL;
415		mtx_unlock(&kenv_lock);
416	}
417	return (0);
418}
419
420/*
421 * Unset an environment variable string.
422 */
423int
424unsetenv(const char *name)
425{
426	char *cp, *oldenv;
427	int i, j;
428
429	KENV_CHECK;
430
431	mtx_lock(&kenv_lock);
432	cp = _getenv_dynamic(name, &i);
433	if (cp != NULL) {
434		oldenv = kenvp[i];
435		for (j = i + 1; kenvp[j] != NULL; j++)
436			kenvp[i++] = kenvp[j];
437		kenvp[i] = NULL;
438		mtx_unlock(&kenv_lock);
439		free(oldenv, M_KENV);
440		return (0);
441	}
442	mtx_unlock(&kenv_lock);
443	return (-1);
444}
445
446/*
447 * Return a string value from an environment variable.
448 */
449int
450getenv_string(const char *name, char *data, int size)
451{
452	char *tmp;
453
454	tmp = getenv(name);
455	if (tmp != NULL) {
456		strlcpy(data, tmp, size);
457		freeenv(tmp);
458		return (1);
459	} else
460		return (0);
461}
462
463/*
464 * Return an integer value from an environment variable.
465 */
466int
467getenv_int(const char *name, int *data)
468{
469	quad_t tmp;
470	int rval;
471
472	rval = getenv_quad(name, &tmp);
473	if (rval)
474		*data = (int) tmp;
475	return (rval);
476}
477
478/*
479 * Return an unsigned integer value from an environment variable.
480 */
481int
482getenv_uint(const char *name, unsigned int *data)
483{
484	quad_t tmp;
485	int rval;
486
487	rval = getenv_quad(name, &tmp);
488	if (rval)
489		*data = (unsigned int) tmp;
490	return (rval);
491}
492
493/*
494 * Return a long value from an environment variable.
495 */
496int
497getenv_long(const char *name, long *data)
498{
499	quad_t tmp;
500	int rval;
501
502	rval = getenv_quad(name, &tmp);
503	if (rval)
504		*data = (long) tmp;
505	return (rval);
506}
507
508/*
509 * Return an unsigned long value from an environment variable.
510 */
511int
512getenv_ulong(const char *name, unsigned long *data)
513{
514	quad_t tmp;
515	int rval;
516
517	rval = getenv_quad(name, &tmp);
518	if (rval)
519		*data = (unsigned long) tmp;
520	return (rval);
521}
522
523/*
524 * Return a quad_t value from an environment variable.
525 */
526int
527getenv_quad(const char *name, quad_t *data)
528{
529	char	*value;
530	char	*vtp;
531	quad_t	iv;
532
533	value = getenv(name);
534	if (value == NULL)
535		return (0);
536	iv = strtoq(value, &vtp, 0);
537	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
538		freeenv(value);
539		return (0);
540	}
541	switch (vtp[0]) {
542	case 't': case 'T':
543		iv *= 1024;
544	case 'g': case 'G':
545		iv *= 1024;
546	case 'm': case 'M':
547		iv *= 1024;
548	case 'k': case 'K':
549		iv *= 1024;
550	case '\0':
551		break;
552	default:
553		freeenv(value);
554		return (0);
555	}
556	*data = iv;
557	freeenv(value);
558	return (1);
559}
560
561/*
562 * Find the next entry after the one which (cp) falls within, return a
563 * pointer to its start or NULL if there are no more.
564 */
565static char *
566kernenv_next(char *cp)
567{
568
569	if (cp != NULL) {
570		while (*cp != 0)
571			cp++;
572		cp++;
573		if (*cp == 0)
574			cp = NULL;
575	}
576	return (cp);
577}
578
579void
580tunable_int_init(void *data)
581{
582	struct tunable_int *d = (struct tunable_int *)data;
583
584	TUNABLE_INT_FETCH(d->path, d->var);
585}
586
587void
588tunable_long_init(void *data)
589{
590	struct tunable_long *d = (struct tunable_long *)data;
591
592	TUNABLE_LONG_FETCH(d->path, d->var);
593}
594
595void
596tunable_ulong_init(void *data)
597{
598	struct tunable_ulong *d = (struct tunable_ulong *)data;
599
600	TUNABLE_ULONG_FETCH(d->path, d->var);
601}
602
603void
604tunable_quad_init(void *data)
605{
606	struct tunable_quad *d = (struct tunable_quad *)data;
607
608	TUNABLE_QUAD_FETCH(d->path, d->var);
609}
610
611void
612tunable_str_init(void *data)
613{
614	struct tunable_str *d = (struct tunable_str *)data;
615
616	TUNABLE_STR_FETCH(d->path, d->var, d->size);
617}
618