xref: /freebsd/sys/kern/kern_environment.c (revision dd41de95a84d979615a2ef11df6850622bf6184e)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3  *
4  * Copyright (c) 1998 Michael Smith
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 /*
30  * The unified bootloader passes us a pointer to a preserved copy of
31  * bootstrap/kernel environment variables.  We convert them to a
32  * dynamic array of strings later when the VM subsystem is up.
33  *
34  * We make these available through the kenv(2) syscall for userland
35  * and through kern_getenv()/freeenv() kern_setenv() kern_unsetenv() testenv() for
36  * the kernel.
37  */
38 
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
41 
42 #include <sys/param.h>
43 #include <sys/proc.h>
44 #include <sys/queue.h>
45 #include <sys/lock.h>
46 #include <sys/malloc.h>
47 #include <sys/mutex.h>
48 #include <sys/priv.h>
49 #include <sys/kenv.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 #include <sys/limits.h>
57 
58 #include <security/mac/mac_framework.h>
59 
60 static char *_getenv_dynamic_locked(const char *name, int *idx);
61 static char *_getenv_dynamic(const char *name, int *idx);
62 
63 static char *kenv_acquire(const char *name);
64 static void kenv_release(const char *buf);
65 
66 static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
67 
68 #define KENV_SIZE	512	/* Maximum number of environment strings */
69 
70 static uma_zone_t kenv_zone;
71 static int	kenv_mvallen = KENV_MVALLEN;
72 
73 /* pointer to the config-generated static environment */
74 char		*kern_envp;
75 
76 /* pointer to the md-static environment */
77 char		*md_envp;
78 static int	md_env_len;
79 static int	md_env_pos;
80 
81 static char	*kernenv_next(char *);
82 
83 /* dynamic environment variables */
84 char		**kenvp;
85 struct mtx	kenv_lock;
86 
87 /*
88  * No need to protect this with a mutex since SYSINITS are single threaded.
89  */
90 bool	dynamic_kenv;
91 
92 #define KENV_CHECK	if (!dynamic_kenv) \
93 			    panic("%s: called before SI_SUB_KMEM", __func__)
94 
95 int
96 sys_kenv(td, uap)
97 	struct thread *td;
98 	struct kenv_args /* {
99 		int what;
100 		const char *name;
101 		char *value;
102 		int len;
103 	} */ *uap;
104 {
105 	char *name, *value, *buffer = NULL;
106 	size_t len, done, needed, buflen;
107 	int error, i;
108 
109 	KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = false"));
110 
111 	error = 0;
112 	if (uap->what == KENV_DUMP) {
113 #ifdef MAC
114 		error = mac_kenv_check_dump(td->td_ucred);
115 		if (error)
116 			return (error);
117 #endif
118 		done = needed = 0;
119 		buflen = uap->len;
120 		if (buflen > KENV_SIZE * (KENV_MNAMELEN + kenv_mvallen + 2))
121 			buflen = KENV_SIZE * (KENV_MNAMELEN +
122 			    kenv_mvallen + 2);
123 		if (uap->len > 0 && uap->value != NULL)
124 			buffer = malloc(buflen, M_TEMP, M_WAITOK|M_ZERO);
125 		mtx_lock(&kenv_lock);
126 		for (i = 0; kenvp[i] != NULL; i++) {
127 			len = strlen(kenvp[i]) + 1;
128 			needed += len;
129 			len = min(len, buflen - done);
130 			/*
131 			 * If called with a NULL or insufficiently large
132 			 * buffer, just keep computing the required size.
133 			 */
134 			if (uap->value != NULL && buffer != NULL && len > 0) {
135 				bcopy(kenvp[i], buffer + done, len);
136 				done += len;
137 			}
138 		}
139 		mtx_unlock(&kenv_lock);
140 		if (buffer != NULL) {
141 			error = copyout(buffer, uap->value, done);
142 			free(buffer, M_TEMP);
143 		}
144 		td->td_retval[0] = ((done == needed) ? 0 : needed);
145 		return (error);
146 	}
147 
148 	switch (uap->what) {
149 	case KENV_SET:
150 		error = priv_check(td, PRIV_KENV_SET);
151 		if (error)
152 			return (error);
153 		break;
154 
155 	case KENV_UNSET:
156 		error = priv_check(td, PRIV_KENV_UNSET);
157 		if (error)
158 			return (error);
159 		break;
160 	}
161 
162 	name = malloc(KENV_MNAMELEN + 1, M_TEMP, M_WAITOK);
163 
164 	error = copyinstr(uap->name, name, KENV_MNAMELEN + 1, NULL);
165 	if (error)
166 		goto done;
167 
168 	switch (uap->what) {
169 	case KENV_GET:
170 #ifdef MAC
171 		error = mac_kenv_check_get(td->td_ucred, name);
172 		if (error)
173 			goto done;
174 #endif
175 		value = kern_getenv(name);
176 		if (value == NULL) {
177 			error = ENOENT;
178 			goto done;
179 		}
180 		len = strlen(value) + 1;
181 		if (len > uap->len)
182 			len = uap->len;
183 		error = copyout(value, uap->value, len);
184 		freeenv(value);
185 		if (error)
186 			goto done;
187 		td->td_retval[0] = len;
188 		break;
189 	case KENV_SET:
190 		len = uap->len;
191 		if (len < 1) {
192 			error = EINVAL;
193 			goto done;
194 		}
195 		if (len > kenv_mvallen + 1)
196 			len = kenv_mvallen + 1;
197 		value = malloc(len, M_TEMP, M_WAITOK);
198 		error = copyinstr(uap->value, value, len, NULL);
199 		if (error) {
200 			free(value, M_TEMP);
201 			goto done;
202 		}
203 #ifdef MAC
204 		error = mac_kenv_check_set(td->td_ucred, name, value);
205 		if (error == 0)
206 #endif
207 			kern_setenv(name, value);
208 		free(value, M_TEMP);
209 		break;
210 	case KENV_UNSET:
211 #ifdef MAC
212 		error = mac_kenv_check_unset(td->td_ucred, name);
213 		if (error)
214 			goto done;
215 #endif
216 		error = kern_unsetenv(name);
217 		if (error)
218 			error = ENOENT;
219 		break;
220 	default:
221 		error = EINVAL;
222 		break;
223 	}
224 done:
225 	free(name, M_TEMP);
226 	return (error);
227 }
228 
229 /*
230  * Populate the initial kernel environment.
231  *
232  * This is called very early in MD startup, either to provide a copy of the
233  * environment obtained from a boot loader, or to provide an empty buffer into
234  * which MD code can store an initial environment using kern_setenv() calls.
235  *
236  * kern_envp is set to the static_env generated by config(8).  This implements
237  * the env keyword described in config(5).
238  *
239  * If len is non-zero, the caller is providing an empty buffer.  The caller will
240  * subsequently use kern_setenv() to add up to len bytes of initial environment
241  * before the dynamic environment is available.
242  *
243  * If len is zero, the caller is providing a pre-loaded buffer containing
244  * environment strings.  Additional strings cannot be added until the dynamic
245  * environment is available.  The memory pointed to must remain stable at least
246  * until sysinit runs init_dynamic_kenv() and preferably until after SI_SUB_KMEM
247  * is finished so that subr_hints routines may continue to use it until the
248  * environments have been fully merged at the end of the pass.  If no initial
249  * environment is available from the boot loader, passing a NULL pointer allows
250  * the static_env to be installed if it is configured.  In this case, any call
251  * to kern_setenv() prior to the setup of the dynamic environment will result in
252  * a panic.
253  */
254 void
255 init_static_kenv(char *buf, size_t len)
256 {
257 
258 	KASSERT(!dynamic_kenv, ("kenv: dynamic_kenv already initialized"));
259 	/*
260 	 * Suitably sized means it must be able to hold at least one empty
261 	 * variable, otherwise things go belly up if a kern_getenv call is
262 	 * made without a prior call to kern_setenv as we have a malformed
263 	 * environment.
264 	 */
265 	KASSERT(len == 0 || len >= 2,
266 	    ("kenv: static env must be initialized or suitably sized"));
267 	KASSERT(len == 0 || (*buf == '\0' && *(buf + 1) == '\0'),
268 	    ("kenv: sized buffer must be initially empty"));
269 
270 	/*
271 	 * We may be called twice, with the second call needed to relocate
272 	 * md_envp after enabling paging.  md_envp is then garbage if it is
273 	 * not null and the relocation will move it.  Discard it so as to
274 	 * not crash using its old value in our first call to kern_getenv().
275 	 *
276 	 * The second call gives the same environment as the first except
277 	 * in silly configurations where the static env disables itself.
278 	 *
279 	 * Other env calls don't handle possibly-garbage pointers, so must
280 	 * not be made between enabling paging and calling here.
281 	 */
282 	md_envp = NULL;
283 	md_env_len = 0;
284 	md_env_pos = 0;
285 
286 	/*
287 	 * Give the static environment a chance to disable the loader(8)
288 	 * environment first.  This is done with loader_env.disabled=1.
289 	 *
290 	 * static_env and static_hints may both be disabled, but in slightly
291 	 * different ways.  For static_env, we just don't setup kern_envp and
292 	 * it's as if a static env wasn't even provided.  For static_hints,
293 	 * we effectively zero out the buffer to stop the rest of the kernel
294 	 * from being able to use it.
295 	 *
296 	 * We're intentionally setting this up so that static_hints.disabled may
297 	 * be specified in either the MD env or the static env. This keeps us
298 	 * consistent in our new world view.
299 	 *
300 	 * As a warning, the static environment may not be disabled in any way
301 	 * if the static environment has disabled the loader environment.
302 	 */
303 	kern_envp = static_env;
304 	if (!getenv_is_true("loader_env.disabled")) {
305 		md_envp = buf;
306 		md_env_len = len;
307 		md_env_pos = 0;
308 
309 		if (getenv_is_true("static_env.disabled")) {
310 			kern_envp[0] = '\0';
311 			kern_envp[1] = '\0';
312 		}
313 	}
314 	if (getenv_is_true("static_hints.disabled")) {
315 		static_hints[0] = '\0';
316 		static_hints[1] = '\0';
317 	}
318 }
319 
320 static void
321 init_dynamic_kenv_from(char *init_env, int *curpos)
322 {
323 	char *cp, *cpnext, *eqpos, *found;
324 	size_t len;
325 	int i;
326 
327 	if (init_env && *init_env != '\0') {
328 		found = NULL;
329 		i = *curpos;
330 		for (cp = init_env; cp != NULL; cp = cpnext) {
331 			cpnext = kernenv_next(cp);
332 			len = strlen(cp) + 1;
333 			if (len > KENV_MNAMELEN + 1 + kenv_mvallen + 1) {
334 				printf(
335 				"WARNING: too long kenv string, ignoring %s\n",
336 				    cp);
337 				goto sanitize;
338 			}
339 			eqpos = strchr(cp, '=');
340 			if (eqpos == NULL) {
341 				printf(
342 				"WARNING: malformed static env value, ignoring %s\n",
343 				    cp);
344 				goto sanitize;
345 			}
346 			*eqpos = 0;
347 			/*
348 			 * De-dupe the environment as we go.  We don't add the
349 			 * duplicated assignments because config(8) will flip
350 			 * the order of the static environment around to make
351 			 * kernel processing match the order of specification
352 			 * in the kernel config.
353 			 */
354 			found = _getenv_dynamic_locked(cp, NULL);
355 			*eqpos = '=';
356 			if (found != NULL)
357 				goto sanitize;
358 			if (i > KENV_SIZE) {
359 				printf(
360 				"WARNING: too many kenv strings, ignoring %s\n",
361 				    cp);
362 				goto sanitize;
363 			}
364 
365 			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
366 			strcpy(kenvp[i++], cp);
367 sanitize:
368 			explicit_bzero(cp, len - 1);
369 		}
370 		*curpos = i;
371 	}
372 }
373 
374 /*
375  * Setup the dynamic kernel environment.
376  */
377 static void
378 init_dynamic_kenv(void *data __unused)
379 {
380 	int dynamic_envpos;
381 	int size;
382 
383 	TUNABLE_INT_FETCH("kenv_mvallen", &kenv_mvallen);
384 	size = KENV_MNAMELEN + 1 + kenv_mvallen + 1;
385 
386 	kenv_zone = uma_zcreate("kenv", size, NULL, NULL, NULL, NULL,
387 	    UMA_ALIGN_PTR, 0);
388 
389 	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
390 		M_WAITOK | M_ZERO);
391 
392 	dynamic_envpos = 0;
393 	init_dynamic_kenv_from(md_envp, &dynamic_envpos);
394 	init_dynamic_kenv_from(kern_envp, &dynamic_envpos);
395 	kenvp[dynamic_envpos] = NULL;
396 
397 	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
398 	dynamic_kenv = true;
399 }
400 SYSINIT(kenv, SI_SUB_KMEM + 1, SI_ORDER_FIRST, init_dynamic_kenv, NULL);
401 
402 void
403 freeenv(char *env)
404 {
405 
406 	if (dynamic_kenv && env != NULL) {
407 		explicit_bzero(env, strlen(env));
408 		uma_zfree(kenv_zone, env);
409 	}
410 }
411 
412 /*
413  * Internal functions for string lookup.
414  */
415 static char *
416 _getenv_dynamic_locked(const char *name, int *idx)
417 {
418 	char *cp;
419 	int len, i;
420 
421 	len = strlen(name);
422 	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
423 		if ((strncmp(cp, name, len) == 0) &&
424 		    (cp[len] == '=')) {
425 			if (idx != NULL)
426 				*idx = i;
427 			return (cp + len + 1);
428 		}
429 	}
430 	return (NULL);
431 }
432 
433 static char *
434 _getenv_dynamic(const char *name, int *idx)
435 {
436 
437 	mtx_assert(&kenv_lock, MA_OWNED);
438 	return (_getenv_dynamic_locked(name, idx));
439 }
440 
441 static char *
442 _getenv_static_from(char *chkenv, const char *name)
443 {
444 	char *cp, *ep;
445 	int len;
446 
447 	for (cp = chkenv; cp != NULL; cp = kernenv_next(cp)) {
448 		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
449 			;
450 		if (*ep != '=')
451 			continue;
452 		len = ep - cp;
453 		ep++;
454 		if (!strncmp(name, cp, len) && name[len] == 0)
455 			return (ep);
456 	}
457 	return (NULL);
458 }
459 
460 static char *
461 _getenv_static(const char *name)
462 {
463 	char *val;
464 
465 	val = _getenv_static_from(md_envp, name);
466 	if (val != NULL)
467 		return (val);
468 	val = _getenv_static_from(kern_envp, name);
469 	if (val != NULL)
470 		return (val);
471 	return (NULL);
472 }
473 
474 /*
475  * Look up an environment variable by name.
476  * Return a pointer to the string if found.
477  * The pointer has to be freed with freeenv()
478  * after use.
479  */
480 char *
481 kern_getenv(const char *name)
482 {
483 	char *cp, *ret;
484 	int len;
485 
486 	if (dynamic_kenv) {
487 		len = KENV_MNAMELEN + 1 + kenv_mvallen + 1;
488 		ret = uma_zalloc(kenv_zone, M_WAITOK | M_ZERO);
489 		mtx_lock(&kenv_lock);
490 		cp = _getenv_dynamic(name, NULL);
491 		if (cp != NULL)
492 			strlcpy(ret, cp, len);
493 		mtx_unlock(&kenv_lock);
494 		if (cp == NULL) {
495 			uma_zfree(kenv_zone, ret);
496 			ret = NULL;
497 		}
498 	} else
499 		ret = _getenv_static(name);
500 
501 	return (ret);
502 }
503 
504 /*
505  * Test if an environment variable is defined.
506  */
507 int
508 testenv(const char *name)
509 {
510 	char *cp;
511 
512 	cp = kenv_acquire(name);
513 	kenv_release(cp);
514 
515 	if (cp != NULL)
516 		return (1);
517 	return (0);
518 }
519 
520 /*
521  * Set an environment variable in the MD-static environment.  This cannot
522  * feasibly be done on config(8)-generated static environments as they don't
523  * generally include space for extra variables.
524  */
525 static int
526 setenv_static(const char *name, const char *value)
527 {
528 	int len;
529 
530 	if (md_env_pos >= md_env_len)
531 		return (-1);
532 
533 	/* Check space for x=y and two nuls */
534 	len = strlen(name) + strlen(value);
535 	if (len + 3 < md_env_len - md_env_pos) {
536 		len = sprintf(&md_envp[md_env_pos], "%s=%s", name, value);
537 		md_env_pos += len+1;
538 		md_envp[md_env_pos] = '\0';
539 		return (0);
540 	} else
541 		return (-1);
542 
543 }
544 
545 /*
546  * Set an environment variable by name.
547  */
548 int
549 kern_setenv(const char *name, const char *value)
550 {
551 	char *buf, *cp, *oldenv;
552 	int namelen, vallen, i;
553 
554 	if (!dynamic_kenv && md_env_len > 0)
555 		return (setenv_static(name, value));
556 
557 	KENV_CHECK;
558 
559 	namelen = strlen(name) + 1;
560 	if (namelen > KENV_MNAMELEN + 1)
561 		return (-1);
562 	vallen = strlen(value) + 1;
563 	if (vallen > kenv_mvallen + 1)
564 		return (-1);
565 	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
566 	sprintf(buf, "%s=%s", name, value);
567 
568 	mtx_lock(&kenv_lock);
569 	cp = _getenv_dynamic(name, &i);
570 	if (cp != NULL) {
571 		oldenv = kenvp[i];
572 		kenvp[i] = buf;
573 		mtx_unlock(&kenv_lock);
574 		free(oldenv, M_KENV);
575 	} else {
576 		/* We add the option if it wasn't found */
577 		for (i = 0; (cp = kenvp[i]) != NULL; i++)
578 			;
579 
580 		/* Bounds checking */
581 		if (i < 0 || i >= KENV_SIZE) {
582 			free(buf, M_KENV);
583 			mtx_unlock(&kenv_lock);
584 			return (-1);
585 		}
586 
587 		kenvp[i] = buf;
588 		kenvp[i + 1] = NULL;
589 		mtx_unlock(&kenv_lock);
590 	}
591 	return (0);
592 }
593 
594 /*
595  * Unset an environment variable string.
596  */
597 int
598 kern_unsetenv(const char *name)
599 {
600 	char *cp, *oldenv;
601 	int i, j;
602 
603 	KENV_CHECK;
604 
605 	mtx_lock(&kenv_lock);
606 	cp = _getenv_dynamic(name, &i);
607 	if (cp != NULL) {
608 		oldenv = kenvp[i];
609 		for (j = i + 1; kenvp[j] != NULL; j++)
610 			kenvp[i++] = kenvp[j];
611 		kenvp[i] = NULL;
612 		mtx_unlock(&kenv_lock);
613 		zfree(oldenv, M_KENV);
614 		return (0);
615 	}
616 	mtx_unlock(&kenv_lock);
617 	return (-1);
618 }
619 
620 /*
621  * Return the internal kenv buffer for the variable name, if it exists.
622  * If the dynamic kenv is initialized and the name is present, return
623  * with kenv_lock held.
624  */
625 static char *
626 kenv_acquire(const char *name)
627 {
628 	char *value;
629 
630 	if (dynamic_kenv) {
631 		mtx_lock(&kenv_lock);
632 		value = _getenv_dynamic(name, NULL);
633 		if (value == NULL)
634 			mtx_unlock(&kenv_lock);
635 		return (value);
636 	} else
637 		return (_getenv_static(name));
638 }
639 
640 /*
641  * Undo a previous kenv_acquire() operation
642  */
643 static void
644 kenv_release(const char *buf)
645 {
646 	if ((buf != NULL) && dynamic_kenv)
647 		mtx_unlock(&kenv_lock);
648 }
649 
650 /*
651  * Return a string value from an environment variable.
652  */
653 int
654 getenv_string(const char *name, char *data, int size)
655 {
656 	char *cp;
657 
658 	cp = kenv_acquire(name);
659 
660 	if (cp != NULL)
661 		strlcpy(data, cp, size);
662 
663 	kenv_release(cp);
664 
665 	return (cp != NULL);
666 }
667 
668 /*
669  * Return an array of integers at the given type size and signedness.
670  */
671 int
672 getenv_array(const char *name, void *pdata, int size, int *psize,
673     int type_size, bool allow_signed)
674 {
675 	uint8_t shift;
676 	int64_t value;
677 	int64_t old;
678 	const char *buf;
679 	char *end;
680 	const char *ptr;
681 	int n;
682 	int rc;
683 
684 	rc = 0;			  /* assume failure */
685 
686 	buf = kenv_acquire(name);
687 	if (buf == NULL)
688 		goto error;
689 
690 	/* get maximum number of elements */
691 	size /= type_size;
692 
693 	n = 0;
694 
695 	for (ptr = buf; *ptr != 0; ) {
696 		value = strtoq(ptr, &end, 0);
697 
698 		/* check if signed numbers are allowed */
699 		if (value < 0 && !allow_signed)
700 			goto error;
701 
702 		/* check for invalid value */
703 		if (ptr == end)
704 			goto error;
705 
706 		/* check for valid suffix */
707 		switch (*end) {
708 		case 't':
709 		case 'T':
710 			shift = 40;
711 			end++;
712 			break;
713 		case 'g':
714 		case 'G':
715 			shift = 30;
716 			end++;
717 			break;
718 		case 'm':
719 		case 'M':
720 			shift = 20;
721 			end++;
722 			break;
723 		case 'k':
724 		case 'K':
725 			shift = 10;
726 			end++;
727 			break;
728 		case ' ':
729 		case '\t':
730 		case ',':
731 		case 0:
732 			shift = 0;
733 			break;
734 		default:
735 			/* garbage after numeric value */
736 			goto error;
737 		}
738 
739 		/* skip till next value, if any */
740 		while (*end == '\t' || *end == ',' || *end == ' ')
741 			end++;
742 
743 		/* update pointer */
744 		ptr = end;
745 
746 		/* apply shift */
747 		old = value;
748 		value <<= shift;
749 
750 		/* overflow check */
751 		if ((value >> shift) != old)
752 			goto error;
753 
754 		/* check for buffer overflow */
755 		if (n >= size)
756 			goto error;
757 
758 		/* store value according to type size */
759 		switch (type_size) {
760 		case 1:
761 			if (allow_signed) {
762 				if (value < SCHAR_MIN || value > SCHAR_MAX)
763 					goto error;
764 			} else {
765 				if (value < 0 || value > UCHAR_MAX)
766 					goto error;
767 			}
768 			((uint8_t *)pdata)[n] = (uint8_t)value;
769 			break;
770 		case 2:
771 			if (allow_signed) {
772 				if (value < SHRT_MIN || value > SHRT_MAX)
773 					goto error;
774 			} else {
775 				if (value < 0 || value > USHRT_MAX)
776 					goto error;
777 			}
778 			((uint16_t *)pdata)[n] = (uint16_t)value;
779 			break;
780 		case 4:
781 			if (allow_signed) {
782 				if (value < INT_MIN || value > INT_MAX)
783 					goto error;
784 			} else {
785 				if (value > UINT_MAX)
786 					goto error;
787 			}
788 			((uint32_t *)pdata)[n] = (uint32_t)value;
789 			break;
790 		case 8:
791 			((uint64_t *)pdata)[n] = (uint64_t)value;
792 			break;
793 		default:
794 			goto error;
795 		}
796 		n++;
797 	}
798 	*psize = n * type_size;
799 
800 	if (n != 0)
801 		rc = 1;	/* success */
802 error:
803 	kenv_release(buf);
804 	return (rc);
805 }
806 
807 /*
808  * Return an integer value from an environment variable.
809  */
810 int
811 getenv_int(const char *name, int *data)
812 {
813 	quad_t tmp;
814 	int rval;
815 
816 	rval = getenv_quad(name, &tmp);
817 	if (rval)
818 		*data = (int) tmp;
819 	return (rval);
820 }
821 
822 /*
823  * Return an unsigned integer value from an environment variable.
824  */
825 int
826 getenv_uint(const char *name, unsigned int *data)
827 {
828 	quad_t tmp;
829 	int rval;
830 
831 	rval = getenv_quad(name, &tmp);
832 	if (rval)
833 		*data = (unsigned int) tmp;
834 	return (rval);
835 }
836 
837 /*
838  * Return an int64_t value from an environment variable.
839  */
840 int
841 getenv_int64(const char *name, int64_t *data)
842 {
843 	quad_t tmp;
844 	int64_t rval;
845 
846 	rval = getenv_quad(name, &tmp);
847 	if (rval)
848 		*data = (int64_t) tmp;
849 	return (rval);
850 }
851 
852 /*
853  * Return an uint64_t value from an environment variable.
854  */
855 int
856 getenv_uint64(const char *name, uint64_t *data)
857 {
858 	quad_t tmp;
859 	uint64_t rval;
860 
861 	rval = getenv_quad(name, &tmp);
862 	if (rval)
863 		*data = (uint64_t) tmp;
864 	return (rval);
865 }
866 
867 /*
868  * Return a long value from an environment variable.
869  */
870 int
871 getenv_long(const char *name, long *data)
872 {
873 	quad_t tmp;
874 	int rval;
875 
876 	rval = getenv_quad(name, &tmp);
877 	if (rval)
878 		*data = (long) tmp;
879 	return (rval);
880 }
881 
882 /*
883  * Return an unsigned long value from an environment variable.
884  */
885 int
886 getenv_ulong(const char *name, unsigned long *data)
887 {
888 	quad_t tmp;
889 	int rval;
890 
891 	rval = getenv_quad(name, &tmp);
892 	if (rval)
893 		*data = (unsigned long) tmp;
894 	return (rval);
895 }
896 
897 /*
898  * Return a quad_t value from an environment variable.
899  */
900 int
901 getenv_quad(const char *name, quad_t *data)
902 {
903 	const char	*value;
904 	char		suffix, *vtp;
905 	quad_t		iv;
906 
907 	value = kenv_acquire(name);
908 	if (value == NULL) {
909 		goto error;
910 	}
911 	iv = strtoq(value, &vtp, 0);
912 	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
913 		goto error;
914 	}
915 	suffix = vtp[0];
916 	kenv_release(value);
917 	switch (suffix) {
918 	case 't': case 'T':
919 		iv *= 1024;
920 		/* FALLTHROUGH */
921 	case 'g': case 'G':
922 		iv *= 1024;
923 		/* FALLTHROUGH */
924 	case 'm': case 'M':
925 		iv *= 1024;
926 		/* FALLTHROUGH */
927 	case 'k': case 'K':
928 		iv *= 1024;
929 	case '\0':
930 		break;
931 	default:
932 		return (0);
933 	}
934 	*data = iv;
935 	return (1);
936 error:
937 	kenv_release(value);
938 	return (0);
939 }
940 
941 /*
942  * Return a boolean value from an environment variable. This can be in
943  * numerical or string form, i.e. "1" or "true".
944  */
945 int
946 getenv_bool(const char *name, bool *data)
947 {
948 	char *val;
949 	int ret = 0;
950 
951 	if (name == NULL)
952 		return (0);
953 
954 	val = kern_getenv(name);
955 	if (val == NULL)
956 		return (0);
957 
958 	if ((strcmp(val, "1") == 0) || (strcasecmp(val, "true") == 0)) {
959 		*data = true;
960 		ret = 1;
961 	} else if ((strcmp(val, "0") == 0) || (strcasecmp(val, "false") == 0)) {
962 		*data = false;
963 		ret = 1;
964 	} else {
965 		/* Spit out a warning for malformed boolean variables. */
966 		printf("Environment variable %s has non-boolean value \"%s\"\n",
967 		    name, val);
968 	}
969 	freeenv(val);
970 
971 	return (ret);
972 }
973 
974 /*
975  * Wrapper around getenv_bool to easily check for true.
976  */
977 bool
978 getenv_is_true(const char *name)
979 {
980 	bool val;
981 
982 	if (getenv_bool(name, &val) != 0)
983 		return (val);
984 	return (false);
985 }
986 
987 /*
988  * Wrapper around getenv_bool to easily check for false.
989  */
990 bool
991 getenv_is_false(const char *name)
992 {
993 	bool val;
994 
995 	if (getenv_bool(name, &val) != 0)
996 		return (!val);
997 	return (false);
998 }
999 
1000 /*
1001  * Find the next entry after the one which (cp) falls within, return a
1002  * pointer to its start or NULL if there are no more.
1003  */
1004 static char *
1005 kernenv_next(char *cp)
1006 {
1007 
1008 	if (cp != NULL) {
1009 		while (*cp != 0)
1010 			cp++;
1011 		cp++;
1012 		if (*cp == 0)
1013 			cp = NULL;
1014 	}
1015 	return (cp);
1016 }
1017 
1018 void
1019 tunable_int_init(void *data)
1020 {
1021 	struct tunable_int *d = (struct tunable_int *)data;
1022 
1023 	TUNABLE_INT_FETCH(d->path, d->var);
1024 }
1025 
1026 void
1027 tunable_long_init(void *data)
1028 {
1029 	struct tunable_long *d = (struct tunable_long *)data;
1030 
1031 	TUNABLE_LONG_FETCH(d->path, d->var);
1032 }
1033 
1034 void
1035 tunable_ulong_init(void *data)
1036 {
1037 	struct tunable_ulong *d = (struct tunable_ulong *)data;
1038 
1039 	TUNABLE_ULONG_FETCH(d->path, d->var);
1040 }
1041 
1042 void
1043 tunable_int64_init(void *data)
1044 {
1045 	struct tunable_int64 *d = (struct tunable_int64 *)data;
1046 
1047 	TUNABLE_INT64_FETCH(d->path, d->var);
1048 }
1049 
1050 void
1051 tunable_uint64_init(void *data)
1052 {
1053 	struct tunable_uint64 *d = (struct tunable_uint64 *)data;
1054 
1055 	TUNABLE_UINT64_FETCH(d->path, d->var);
1056 }
1057 
1058 void
1059 tunable_quad_init(void *data)
1060 {
1061 	struct tunable_quad *d = (struct tunable_quad *)data;
1062 
1063 	TUNABLE_QUAD_FETCH(d->path, d->var);
1064 }
1065 
1066 void
1067 tunable_bool_init(void *data)
1068 {
1069 	struct tunable_bool *d = (struct tunable_bool *)data;
1070 
1071 	TUNABLE_BOOL_FETCH(d->path, d->var);
1072 }
1073 
1074 void
1075 tunable_str_init(void *data)
1076 {
1077 	struct tunable_str *d = (struct tunable_str *)data;
1078 
1079 	TUNABLE_STR_FETCH(d->path, d->var, d->size);
1080 }
1081