xref: /freebsd/sys/kern/kern_environment.c (revision 0b57cec536236d46e3dba9bd041533462f33dbb7)
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/kernel.h>
50 #include <sys/systm.h>
51 #include <sys/sysent.h>
52 #include <sys/sysproto.h>
53 #include <sys/libkern.h>
54 #include <sys/kenv.h>
55 #include <sys/limits.h>
56 
57 #include <security/mac/mac_framework.h>
58 
59 static char *_getenv_dynamic_locked(const char *name, int *idx);
60 static char *_getenv_dynamic(const char *name, int *idx);
61 
62 static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
63 
64 #define KENV_SIZE	512	/* Maximum number of environment strings */
65 
66 /* pointer to the config-generated static environment */
67 char		*kern_envp;
68 
69 /* pointer to the md-static environment */
70 char		*md_envp;
71 static int	md_env_len;
72 static int	md_env_pos;
73 
74 static char	*kernenv_next(char *);
75 
76 /* dynamic environment variables */
77 char		**kenvp;
78 struct mtx	kenv_lock;
79 
80 /*
81  * No need to protect this with a mutex since SYSINITS are single threaded.
82  */
83 bool	dynamic_kenv;
84 
85 #define KENV_CHECK	if (!dynamic_kenv) \
86 			    panic("%s: called before SI_SUB_KMEM", __func__)
87 
88 int
89 sys_kenv(td, uap)
90 	struct thread *td;
91 	struct kenv_args /* {
92 		int what;
93 		const char *name;
94 		char *value;
95 		int len;
96 	} */ *uap;
97 {
98 	char *name, *value, *buffer = NULL;
99 	size_t len, done, needed, buflen;
100 	int error, i;
101 
102 	KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = false"));
103 
104 	error = 0;
105 	if (uap->what == KENV_DUMP) {
106 #ifdef MAC
107 		error = mac_kenv_check_dump(td->td_ucred);
108 		if (error)
109 			return (error);
110 #endif
111 		done = needed = 0;
112 		buflen = uap->len;
113 		if (buflen > KENV_SIZE * (KENV_MNAMELEN + KENV_MVALLEN + 2))
114 			buflen = KENV_SIZE * (KENV_MNAMELEN +
115 			    KENV_MVALLEN + 2);
116 		if (uap->len > 0 && uap->value != NULL)
117 			buffer = malloc(buflen, M_TEMP, M_WAITOK|M_ZERO);
118 		mtx_lock(&kenv_lock);
119 		for (i = 0; kenvp[i] != NULL; i++) {
120 			len = strlen(kenvp[i]) + 1;
121 			needed += len;
122 			len = min(len, buflen - done);
123 			/*
124 			 * If called with a NULL or insufficiently large
125 			 * buffer, just keep computing the required size.
126 			 */
127 			if (uap->value != NULL && buffer != NULL && len > 0) {
128 				bcopy(kenvp[i], buffer + done, len);
129 				done += len;
130 			}
131 		}
132 		mtx_unlock(&kenv_lock);
133 		if (buffer != NULL) {
134 			error = copyout(buffer, uap->value, done);
135 			free(buffer, M_TEMP);
136 		}
137 		td->td_retval[0] = ((done == needed) ? 0 : needed);
138 		return (error);
139 	}
140 
141 	switch (uap->what) {
142 	case KENV_SET:
143 		error = priv_check(td, PRIV_KENV_SET);
144 		if (error)
145 			return (error);
146 		break;
147 
148 	case KENV_UNSET:
149 		error = priv_check(td, PRIV_KENV_UNSET);
150 		if (error)
151 			return (error);
152 		break;
153 	}
154 
155 	name = malloc(KENV_MNAMELEN + 1, M_TEMP, M_WAITOK);
156 
157 	error = copyinstr(uap->name, name, KENV_MNAMELEN + 1, NULL);
158 	if (error)
159 		goto done;
160 
161 	switch (uap->what) {
162 	case KENV_GET:
163 #ifdef MAC
164 		error = mac_kenv_check_get(td->td_ucred, name);
165 		if (error)
166 			goto done;
167 #endif
168 		value = kern_getenv(name);
169 		if (value == NULL) {
170 			error = ENOENT;
171 			goto done;
172 		}
173 		len = strlen(value) + 1;
174 		if (len > uap->len)
175 			len = uap->len;
176 		error = copyout(value, uap->value, len);
177 		freeenv(value);
178 		if (error)
179 			goto done;
180 		td->td_retval[0] = len;
181 		break;
182 	case KENV_SET:
183 		len = uap->len;
184 		if (len < 1) {
185 			error = EINVAL;
186 			goto done;
187 		}
188 		if (len > KENV_MVALLEN + 1)
189 			len = KENV_MVALLEN + 1;
190 		value = malloc(len, M_TEMP, M_WAITOK);
191 		error = copyinstr(uap->value, value, len, NULL);
192 		if (error) {
193 			free(value, M_TEMP);
194 			goto done;
195 		}
196 #ifdef MAC
197 		error = mac_kenv_check_set(td->td_ucred, name, value);
198 		if (error == 0)
199 #endif
200 			kern_setenv(name, value);
201 		free(value, M_TEMP);
202 		break;
203 	case KENV_UNSET:
204 #ifdef MAC
205 		error = mac_kenv_check_unset(td->td_ucred, name);
206 		if (error)
207 			goto done;
208 #endif
209 		error = kern_unsetenv(name);
210 		if (error)
211 			error = ENOENT;
212 		break;
213 	default:
214 		error = EINVAL;
215 		break;
216 	}
217 done:
218 	free(name, M_TEMP);
219 	return (error);
220 }
221 
222 /*
223  * Populate the initial kernel environment.
224  *
225  * This is called very early in MD startup, either to provide a copy of the
226  * environment obtained from a boot loader, or to provide an empty buffer into
227  * which MD code can store an initial environment using kern_setenv() calls.
228  *
229  * kern_envp is set to the static_env generated by config(8).  This implements
230  * the env keyword described in config(5).
231  *
232  * If len is non-zero, the caller is providing an empty buffer.  The caller will
233  * subsequently use kern_setenv() to add up to len bytes of initial environment
234  * before the dynamic environment is available.
235  *
236  * If len is zero, the caller is providing a pre-loaded buffer containing
237  * environment strings.  Additional strings cannot be added until the dynamic
238  * environment is available.  The memory pointed to must remain stable at least
239  * until sysinit runs init_dynamic_kenv() and preferably until after SI_SUB_KMEM
240  * is finished so that subr_hints routines may continue to use it until the
241  * environments have been fully merged at the end of the pass.  If no initial
242  * environment is available from the boot loader, passing a NULL pointer allows
243  * the static_env to be installed if it is configured.  In this case, any call
244  * to kern_setenv() prior to the setup of the dynamic environment will result in
245  * a panic.
246  */
247 void
248 init_static_kenv(char *buf, size_t len)
249 {
250 	char *eval;
251 
252 	KASSERT(!dynamic_kenv, ("kenv: dynamic_kenv already initialized"));
253 	/*
254 	 * Suitably sized means it must be able to hold at least one empty
255 	 * variable, otherwise things go belly up if a kern_getenv call is
256 	 * made without a prior call to kern_setenv as we have a malformed
257 	 * environment.
258 	 */
259 	KASSERT(len == 0 || len >= 2,
260 	    ("kenv: static env must be initialized or suitably sized"));
261 	KASSERT(len == 0 || (*buf == '\0' && *(buf + 1) == '\0'),
262 	    ("kenv: sized buffer must be initially empty"));
263 
264 	/*
265 	 * We may be called twice, with the second call needed to relocate
266 	 * md_envp after enabling paging.  md_envp is then garbage if it is
267 	 * not null and the relocation will move it.  Discard it so as to
268 	 * not crash using its old value in our first call to kern_getenv().
269 	 *
270 	 * The second call gives the same environment as the first except
271 	 * in silly configurations where the static env disables itself.
272 	 *
273 	 * Other env calls don't handle possibly-garbage pointers, so must
274 	 * not be made between enabling paging and calling here.
275 	 */
276 	md_envp = NULL;
277 	md_env_len = 0;
278 	md_env_pos = 0;
279 
280 	/*
281 	 * Give the static environment a chance to disable the loader(8)
282 	 * environment first.  This is done with loader_env.disabled=1.
283 	 *
284 	 * static_env and static_hints may both be disabled, but in slightly
285 	 * different ways.  For static_env, we just don't setup kern_envp and
286 	 * it's as if a static env wasn't even provided.  For static_hints,
287 	 * we effectively zero out the buffer to stop the rest of the kernel
288 	 * from being able to use it.
289 	 *
290 	 * We're intentionally setting this up so that static_hints.disabled may
291 	 * be specified in either the MD env or the static env. This keeps us
292 	 * consistent in our new world view.
293 	 *
294 	 * As a warning, the static environment may not be disabled in any way
295 	 * if the static environment has disabled the loader environment.
296 	 */
297 	kern_envp = static_env;
298 	eval = kern_getenv("loader_env.disabled");
299 	if (eval == NULL || strcmp(eval, "1") != 0) {
300 		md_envp = buf;
301 		md_env_len = len;
302 		md_env_pos = 0;
303 
304 		eval = kern_getenv("static_env.disabled");
305 		if (eval != NULL && strcmp(eval, "1") == 0) {
306 			kern_envp[0] = '\0';
307 			kern_envp[1] = '\0';
308 		}
309 	}
310 	eval = kern_getenv("static_hints.disabled");
311 	if (eval != NULL && strcmp(eval, "1") == 0) {
312 		static_hints[0] = '\0';
313 		static_hints[1] = '\0';
314 	}
315 }
316 
317 static void
318 init_dynamic_kenv_from(char *init_env, int *curpos)
319 {
320 	char *cp, *cpnext, *eqpos, *found;
321 	size_t len;
322 	int i;
323 
324 	if (init_env && *init_env != '\0') {
325 		found = NULL;
326 		i = *curpos;
327 		for (cp = init_env; cp != NULL; cp = cpnext) {
328 			cpnext = kernenv_next(cp);
329 			len = strlen(cp) + 1;
330 			if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
331 				printf(
332 				"WARNING: too long kenv string, ignoring %s\n",
333 				    cp);
334 				goto sanitize;
335 			}
336 			eqpos = strchr(cp, '=');
337 			if (eqpos == NULL) {
338 				printf(
339 				"WARNING: malformed static env value, ignoring %s\n",
340 				    cp);
341 				goto sanitize;
342 			}
343 			*eqpos = 0;
344 			/*
345 			 * De-dupe the environment as we go.  We don't add the
346 			 * duplicated assignments because config(8) will flip
347 			 * the order of the static environment around to make
348 			 * kernel processing match the order of specification
349 			 * in the kernel config.
350 			 */
351 			found = _getenv_dynamic_locked(cp, NULL);
352 			*eqpos = '=';
353 			if (found != NULL)
354 				goto sanitize;
355 			if (i > KENV_SIZE) {
356 				printf(
357 				"WARNING: too many kenv strings, ignoring %s\n",
358 				    cp);
359 				goto sanitize;
360 			}
361 
362 			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
363 			strcpy(kenvp[i++], cp);
364 sanitize:
365 			explicit_bzero(cp, len - 1);
366 		}
367 		*curpos = i;
368 	}
369 }
370 
371 /*
372  * Setup the dynamic kernel environment.
373  */
374 static void
375 init_dynamic_kenv(void *data __unused)
376 {
377 	int dynamic_envpos;
378 
379 	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
380 		M_WAITOK | M_ZERO);
381 
382 	dynamic_envpos = 0;
383 	init_dynamic_kenv_from(md_envp, &dynamic_envpos);
384 	init_dynamic_kenv_from(kern_envp, &dynamic_envpos);
385 	kenvp[dynamic_envpos] = NULL;
386 
387 	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
388 	dynamic_kenv = true;
389 }
390 SYSINIT(kenv, SI_SUB_KMEM + 1, SI_ORDER_FIRST, init_dynamic_kenv, NULL);
391 
392 void
393 freeenv(char *env)
394 {
395 
396 	if (dynamic_kenv && env != NULL) {
397 		explicit_bzero(env, strlen(env));
398 		free(env, M_KENV);
399 	}
400 }
401 
402 /*
403  * Internal functions for string lookup.
404  */
405 static char *
406 _getenv_dynamic_locked(const char *name, int *idx)
407 {
408 	char *cp;
409 	int len, i;
410 
411 	len = strlen(name);
412 	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
413 		if ((strncmp(cp, name, len) == 0) &&
414 		    (cp[len] == '=')) {
415 			if (idx != NULL)
416 				*idx = i;
417 			return (cp + len + 1);
418 		}
419 	}
420 	return (NULL);
421 }
422 
423 static char *
424 _getenv_dynamic(const char *name, int *idx)
425 {
426 
427 	mtx_assert(&kenv_lock, MA_OWNED);
428 	return (_getenv_dynamic_locked(name, idx));
429 }
430 
431 static char *
432 _getenv_static_from(char *chkenv, const char *name)
433 {
434 	char *cp, *ep;
435 	int len;
436 
437 	for (cp = chkenv; cp != NULL; cp = kernenv_next(cp)) {
438 		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
439 			;
440 		if (*ep != '=')
441 			continue;
442 		len = ep - cp;
443 		ep++;
444 		if (!strncmp(name, cp, len) && name[len] == 0)
445 			return (ep);
446 	}
447 	return (NULL);
448 }
449 
450 static char *
451 _getenv_static(const char *name)
452 {
453 	char *val;
454 
455 	val = _getenv_static_from(md_envp, name);
456 	if (val != NULL)
457 		return (val);
458 	val = _getenv_static_from(kern_envp, name);
459 	if (val != NULL)
460 		return (val);
461 	return (NULL);
462 }
463 
464 /*
465  * Look up an environment variable by name.
466  * Return a pointer to the string if found.
467  * The pointer has to be freed with freeenv()
468  * after use.
469  */
470 char *
471 kern_getenv(const char *name)
472 {
473 	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
474 	char *ret;
475 
476 	if (dynamic_kenv) {
477 		if (getenv_string(name, buf, sizeof(buf))) {
478 			ret = strdup(buf, M_KENV);
479 		} else {
480 			ret = NULL;
481 			WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
482 			    "getenv");
483 		}
484 	} else
485 		ret = _getenv_static(name);
486 	return (ret);
487 }
488 
489 /*
490  * Test if an environment variable is defined.
491  */
492 int
493 testenv(const char *name)
494 {
495 	char *cp;
496 
497 	if (dynamic_kenv) {
498 		mtx_lock(&kenv_lock);
499 		cp = _getenv_dynamic(name, NULL);
500 		mtx_unlock(&kenv_lock);
501 	} else
502 		cp = _getenv_static(name);
503 	if (cp != NULL)
504 		return (1);
505 	return (0);
506 }
507 
508 /*
509  * Set an environment variable in the MD-static environment.  This cannot
510  * feasibly be done on config(8)-generated static environments as they don't
511  * generally include space for extra variables.
512  */
513 static int
514 setenv_static(const char *name, const char *value)
515 {
516 	int len;
517 
518 	if (md_env_pos >= md_env_len)
519 		return (-1);
520 
521 	/* Check space for x=y and two nuls */
522 	len = strlen(name) + strlen(value);
523 	if (len + 3 < md_env_len - md_env_pos) {
524 		len = sprintf(&md_envp[md_env_pos], "%s=%s", name, value);
525 		md_env_pos += len+1;
526 		md_envp[md_env_pos] = '\0';
527 		return (0);
528 	} else
529 		return (-1);
530 
531 }
532 
533 /*
534  * Set an environment variable by name.
535  */
536 int
537 kern_setenv(const char *name, const char *value)
538 {
539 	char *buf, *cp, *oldenv;
540 	int namelen, vallen, i;
541 
542 	if (!dynamic_kenv && md_env_len > 0)
543 		return (setenv_static(name, value));
544 
545 	KENV_CHECK;
546 
547 	namelen = strlen(name) + 1;
548 	if (namelen > KENV_MNAMELEN + 1)
549 		return (-1);
550 	vallen = strlen(value) + 1;
551 	if (vallen > KENV_MVALLEN + 1)
552 		return (-1);
553 	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
554 	sprintf(buf, "%s=%s", name, value);
555 
556 	mtx_lock(&kenv_lock);
557 	cp = _getenv_dynamic(name, &i);
558 	if (cp != NULL) {
559 		oldenv = kenvp[i];
560 		kenvp[i] = buf;
561 		mtx_unlock(&kenv_lock);
562 		free(oldenv, M_KENV);
563 	} else {
564 		/* We add the option if it wasn't found */
565 		for (i = 0; (cp = kenvp[i]) != NULL; i++)
566 			;
567 
568 		/* Bounds checking */
569 		if (i < 0 || i >= KENV_SIZE) {
570 			free(buf, M_KENV);
571 			mtx_unlock(&kenv_lock);
572 			return (-1);
573 		}
574 
575 		kenvp[i] = buf;
576 		kenvp[i + 1] = NULL;
577 		mtx_unlock(&kenv_lock);
578 	}
579 	return (0);
580 }
581 
582 /*
583  * Unset an environment variable string.
584  */
585 int
586 kern_unsetenv(const char *name)
587 {
588 	char *cp, *oldenv;
589 	int i, j;
590 
591 	KENV_CHECK;
592 
593 	mtx_lock(&kenv_lock);
594 	cp = _getenv_dynamic(name, &i);
595 	if (cp != NULL) {
596 		oldenv = kenvp[i];
597 		for (j = i + 1; kenvp[j] != NULL; j++)
598 			kenvp[i++] = kenvp[j];
599 		kenvp[i] = NULL;
600 		mtx_unlock(&kenv_lock);
601 		explicit_bzero(oldenv, strlen(oldenv));
602 		free(oldenv, M_KENV);
603 		return (0);
604 	}
605 	mtx_unlock(&kenv_lock);
606 	return (-1);
607 }
608 
609 /*
610  * Return a string value from an environment variable.
611  */
612 int
613 getenv_string(const char *name, char *data, int size)
614 {
615 	char *cp;
616 
617 	if (dynamic_kenv) {
618 		mtx_lock(&kenv_lock);
619 		cp = _getenv_dynamic(name, NULL);
620 		if (cp != NULL)
621 			strlcpy(data, cp, size);
622 		mtx_unlock(&kenv_lock);
623 	} else {
624 		cp = _getenv_static(name);
625 		if (cp != NULL)
626 			strlcpy(data, cp, size);
627 	}
628 	return (cp != NULL);
629 }
630 
631 /*
632  * Return an array of integers at the given type size and signedness.
633  */
634 int
635 getenv_array(const char *name, void *pdata, int size, int *psize,
636     int type_size, bool allow_signed)
637 {
638 	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
639 	uint8_t shift;
640 	int64_t value;
641 	int64_t old;
642 	char *end;
643 	char *ptr;
644 	int n;
645 
646 	if (getenv_string(name, buf, sizeof(buf)) == 0)
647 		return (0);
648 
649 	/* get maximum number of elements */
650 	size /= type_size;
651 
652 	n = 0;
653 
654 	for (ptr = buf; *ptr != 0; ) {
655 
656 		value = strtoq(ptr, &end, 0);
657 
658 		/* check if signed numbers are allowed */
659 		if (value < 0 && !allow_signed)
660 			goto error;
661 
662 		/* check for invalid value */
663 		if (ptr == end)
664 			goto error;
665 
666 		/* check for valid suffix */
667 		switch (*end) {
668 		case 't':
669 		case 'T':
670 			shift = 40;
671 			end++;
672 			break;
673 		case 'g':
674 		case 'G':
675 			shift = 30;
676 			end++;
677 			break;
678 		case 'm':
679 		case 'M':
680 			shift = 20;
681 			end++;
682 			break;
683 		case 'k':
684 		case 'K':
685 			shift = 10;
686 			end++;
687 			break;
688 		case ' ':
689 		case '\t':
690 		case ',':
691 		case 0:
692 			shift = 0;
693 			break;
694 		default:
695 			/* garbage after numeric value */
696 			goto error;
697 		}
698 
699 		/* skip till next value, if any */
700 		while (*end == '\t' || *end == ',' || *end == ' ')
701 			end++;
702 
703 		/* update pointer */
704 		ptr = end;
705 
706 		/* apply shift */
707 		old = value;
708 		value <<= shift;
709 
710 		/* overflow check */
711 		if ((value >> shift) != old)
712 			goto error;
713 
714 		/* check for buffer overflow */
715 		if (n >= size)
716 			goto error;
717 
718 		/* store value according to type size */
719 		switch (type_size) {
720 		case 1:
721 			if (allow_signed) {
722 				if (value < SCHAR_MIN || value > SCHAR_MAX)
723 					goto error;
724 			} else {
725 				if (value < 0 || value > UCHAR_MAX)
726 					goto error;
727 			}
728 			((uint8_t *)pdata)[n] = (uint8_t)value;
729 			break;
730 		case 2:
731 			if (allow_signed) {
732 				if (value < SHRT_MIN || value > SHRT_MAX)
733 					goto error;
734 			} else {
735 				if (value < 0 || value > USHRT_MAX)
736 					goto error;
737 			}
738 			((uint16_t *)pdata)[n] = (uint16_t)value;
739 			break;
740 		case 4:
741 			if (allow_signed) {
742 				if (value < INT_MIN || value > INT_MAX)
743 					goto error;
744 			} else {
745 				if (value > UINT_MAX)
746 					goto error;
747 			}
748 			((uint32_t *)pdata)[n] = (uint32_t)value;
749 			break;
750 		case 8:
751 			((uint64_t *)pdata)[n] = (uint64_t)value;
752 			break;
753 		default:
754 			goto error;
755 		}
756 		n++;
757 	}
758 	*psize = n * type_size;
759 
760 	if (n != 0)
761 		return (1);	/* success */
762 error:
763 	return (0);	/* failure */
764 }
765 
766 /*
767  * Return an integer value from an environment variable.
768  */
769 int
770 getenv_int(const char *name, int *data)
771 {
772 	quad_t tmp;
773 	int rval;
774 
775 	rval = getenv_quad(name, &tmp);
776 	if (rval)
777 		*data = (int) tmp;
778 	return (rval);
779 }
780 
781 /*
782  * Return an unsigned integer value from an environment variable.
783  */
784 int
785 getenv_uint(const char *name, unsigned int *data)
786 {
787 	quad_t tmp;
788 	int rval;
789 
790 	rval = getenv_quad(name, &tmp);
791 	if (rval)
792 		*data = (unsigned int) tmp;
793 	return (rval);
794 }
795 
796 /*
797  * Return an int64_t value from an environment variable.
798  */
799 int
800 getenv_int64(const char *name, int64_t *data)
801 {
802 	quad_t tmp;
803 	int64_t rval;
804 
805 	rval = getenv_quad(name, &tmp);
806 	if (rval)
807 		*data = (int64_t) tmp;
808 	return (rval);
809 }
810 
811 /*
812  * Return an uint64_t value from an environment variable.
813  */
814 int
815 getenv_uint64(const char *name, uint64_t *data)
816 {
817 	quad_t tmp;
818 	uint64_t rval;
819 
820 	rval = getenv_quad(name, &tmp);
821 	if (rval)
822 		*data = (uint64_t) tmp;
823 	return (rval);
824 }
825 
826 /*
827  * Return a long value from an environment variable.
828  */
829 int
830 getenv_long(const char *name, long *data)
831 {
832 	quad_t tmp;
833 	int rval;
834 
835 	rval = getenv_quad(name, &tmp);
836 	if (rval)
837 		*data = (long) tmp;
838 	return (rval);
839 }
840 
841 /*
842  * Return an unsigned long value from an environment variable.
843  */
844 int
845 getenv_ulong(const char *name, unsigned long *data)
846 {
847 	quad_t tmp;
848 	int rval;
849 
850 	rval = getenv_quad(name, &tmp);
851 	if (rval)
852 		*data = (unsigned long) tmp;
853 	return (rval);
854 }
855 
856 /*
857  * Return a quad_t value from an environment variable.
858  */
859 int
860 getenv_quad(const char *name, quad_t *data)
861 {
862 	char	value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
863 	char	*vtp;
864 	quad_t	iv;
865 
866 	if (!getenv_string(name, value, sizeof(value)))
867 		return (0);
868 	iv = strtoq(value, &vtp, 0);
869 	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
870 		return (0);
871 	switch (vtp[0]) {
872 	case 't': case 'T':
873 		iv *= 1024;
874 		/* FALLTHROUGH */
875 	case 'g': case 'G':
876 		iv *= 1024;
877 		/* FALLTHROUGH */
878 	case 'm': case 'M':
879 		iv *= 1024;
880 		/* FALLTHROUGH */
881 	case 'k': case 'K':
882 		iv *= 1024;
883 	case '\0':
884 		break;
885 	default:
886 		return (0);
887 	}
888 	*data = iv;
889 	return (1);
890 }
891 
892 /*
893  * Find the next entry after the one which (cp) falls within, return a
894  * pointer to its start or NULL if there are no more.
895  */
896 static char *
897 kernenv_next(char *cp)
898 {
899 
900 	if (cp != NULL) {
901 		while (*cp != 0)
902 			cp++;
903 		cp++;
904 		if (*cp == 0)
905 			cp = NULL;
906 	}
907 	return (cp);
908 }
909 
910 void
911 tunable_int_init(void *data)
912 {
913 	struct tunable_int *d = (struct tunable_int *)data;
914 
915 	TUNABLE_INT_FETCH(d->path, d->var);
916 }
917 
918 void
919 tunable_long_init(void *data)
920 {
921 	struct tunable_long *d = (struct tunable_long *)data;
922 
923 	TUNABLE_LONG_FETCH(d->path, d->var);
924 }
925 
926 void
927 tunable_ulong_init(void *data)
928 {
929 	struct tunable_ulong *d = (struct tunable_ulong *)data;
930 
931 	TUNABLE_ULONG_FETCH(d->path, d->var);
932 }
933 
934 void
935 tunable_int64_init(void *data)
936 {
937 	struct tunable_int64 *d = (struct tunable_int64 *)data;
938 
939 	TUNABLE_INT64_FETCH(d->path, d->var);
940 }
941 
942 void
943 tunable_uint64_init(void *data)
944 {
945 	struct tunable_uint64 *d = (struct tunable_uint64 *)data;
946 
947 	TUNABLE_UINT64_FETCH(d->path, d->var);
948 }
949 
950 void
951 tunable_quad_init(void *data)
952 {
953 	struct tunable_quad *d = (struct tunable_quad *)data;
954 
955 	TUNABLE_QUAD_FETCH(d->path, d->var);
956 }
957 
958 void
959 tunable_str_init(void *data)
960 {
961 	struct tunable_str *d = (struct tunable_str *)data;
962 
963 	TUNABLE_STR_FETCH(d->path, d->var, d->size);
964 }
965