kern_environment.c revision 222216 
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 222216 2011-05-23 16:40:44Z 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	size_t len;
229	int i;
230
231	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
232		M_WAITOK | M_ZERO);
233	i = 0;
234	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
235		len = strlen(cp) + 1;
236		if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
237			printf("WARNING: too long kenv string, ignoring %s\n",
238			    cp);
239			continue;
240		}
241		if (i < KENV_SIZE) {
242			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
243			strcpy(kenvp[i++], cp);
244		} else
245			printf(
246			    "WARNING: too many kenv strings, ignoring %s\n",
247			    cp);
248	}
249	kenvp[i] = NULL;
250
251	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
252	dynamic_kenv = 1;
253}
254SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
255
256void
257freeenv(char *env)
258{
259
260	if (dynamic_kenv)
261		free(env, M_KENV);
262}
263
264/*
265 * Internal functions for string lookup.
266 */
267static char *
268_getenv_dynamic(const char *name, int *idx)
269{
270	char *cp;
271	int len, i;
272
273	mtx_assert(&kenv_lock, MA_OWNED);
274	len = strlen(name);
275	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
276		if ((strncmp(cp, name, len) == 0) &&
277		    (cp[len] == '=')) {
278			if (idx != NULL)
279				*idx = i;
280			return (cp + len + 1);
281		}
282	}
283	return (NULL);
284}
285
286static char *
287_getenv_static(const char *name)
288{
289	char *cp, *ep;
290	int len;
291
292	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
293		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
294			;
295		if (*ep != '=')
296			continue;
297		len = ep - cp;
298		ep++;
299		if (!strncmp(name, cp, len) && name[len] == 0)
300			return (ep);
301	}
302	return (NULL);
303}
304
305/*
306 * Look up an environment variable by name.
307 * Return a pointer to the string if found.
308 * The pointer has to be freed with freeenv()
309 * after use.
310 */
311char *
312getenv(const char *name)
313{
314	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
315	char *ret, *cp;
316	int len;
317
318	if (dynamic_kenv) {
319		mtx_lock(&kenv_lock);
320		cp = _getenv_dynamic(name, NULL);
321		if (cp != NULL) {
322			strcpy(buf, cp);
323			mtx_unlock(&kenv_lock);
324			len = strlen(buf) + 1;
325			ret = malloc(len, M_KENV, M_WAITOK);
326			strcpy(ret, buf);
327		} else {
328			mtx_unlock(&kenv_lock);
329			ret = NULL;
330			WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
331			    "getenv");
332		}
333	} else
334		ret = _getenv_static(name);
335	return (ret);
336}
337
338/*
339 * Test if an environment variable is defined.
340 */
341int
342testenv(const char *name)
343{
344	char *cp;
345
346	if (dynamic_kenv) {
347		mtx_lock(&kenv_lock);
348		cp = _getenv_dynamic(name, NULL);
349		mtx_unlock(&kenv_lock);
350	} else
351		cp = _getenv_static(name);
352	if (cp != NULL)
353		return (1);
354	return (0);
355}
356
357static int
358setenv_static(const char *name, const char *value)
359{
360	int len;
361
362	if (env_pos >= env_len)
363		return (-1);
364
365	/* Check space for x=y and two nuls */
366	len = strlen(name) + strlen(value);
367	if (len + 3 < env_len - env_pos) {
368		len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
369		env_pos += len+1;
370		kern_envp[env_pos] = '\0';
371		return (0);
372	} else
373		return (-1);
374
375}
376
377/*
378 * Set an environment variable by name.
379 */
380int
381setenv(const char *name, const char *value)
382{
383	char *buf, *cp, *oldenv;
384	int namelen, vallen, i;
385
386	if (dynamic_kenv == 0 && env_len > 0)
387		return (setenv_static(name, value));
388
389	KENV_CHECK;
390
391	namelen = strlen(name) + 1;
392	if (namelen > KENV_MNAMELEN)
393		return (-1);
394	vallen = strlen(value) + 1;
395	if (vallen > KENV_MVALLEN)
396		return (-1);
397	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
398	sprintf(buf, "%s=%s", name, value);
399
400	mtx_lock(&kenv_lock);
401	cp = _getenv_dynamic(name, &i);
402	if (cp != NULL) {
403		oldenv = kenvp[i];
404		kenvp[i] = buf;
405		mtx_unlock(&kenv_lock);
406		free(oldenv, M_KENV);
407	} else {
408		/* We add the option if it wasn't found */
409		for (i = 0; (cp = kenvp[i]) != NULL; i++)
410			;
411
412		/* Bounds checking */
413		if (i < 0 || i >= KENV_SIZE) {
414			free(buf, M_KENV);
415			mtx_unlock(&kenv_lock);
416			return (-1);
417		}
418
419		kenvp[i] = buf;
420		kenvp[i + 1] = NULL;
421		mtx_unlock(&kenv_lock);
422	}
423	return (0);
424}
425
426/*
427 * Unset an environment variable string.
428 */
429int
430unsetenv(const char *name)
431{
432	char *cp, *oldenv;
433	int i, j;
434
435	KENV_CHECK;
436
437	mtx_lock(&kenv_lock);
438	cp = _getenv_dynamic(name, &i);
439	if (cp != NULL) {
440		oldenv = kenvp[i];
441		for (j = i + 1; kenvp[j] != NULL; j++)
442			kenvp[i++] = kenvp[j];
443		kenvp[i] = NULL;
444		mtx_unlock(&kenv_lock);
445		free(oldenv, M_KENV);
446		return (0);
447	}
448	mtx_unlock(&kenv_lock);
449	return (-1);
450}
451
452/*
453 * Return a string value from an environment variable.
454 */
455int
456getenv_string(const char *name, char *data, int size)
457{
458	char *tmp;
459
460	tmp = getenv(name);
461	if (tmp != NULL) {
462		strlcpy(data, tmp, size);
463		freeenv(tmp);
464		return (1);
465	} else
466		return (0);
467}
468
469/*
470 * Return an integer value from an environment variable.
471 */
472int
473getenv_int(const char *name, int *data)
474{
475	quad_t tmp;
476	int rval;
477
478	rval = getenv_quad(name, &tmp);
479	if (rval)
480		*data = (int) tmp;
481	return (rval);
482}
483
484/*
485 * Return an unsigned integer value from an environment variable.
486 */
487int
488getenv_uint(const char *name, unsigned int *data)
489{
490	quad_t tmp;
491	int rval;
492
493	rval = getenv_quad(name, &tmp);
494	if (rval)
495		*data = (unsigned int) tmp;
496	return (rval);
497}
498
499/*
500 * Return a long value from an environment variable.
501 */
502int
503getenv_long(const char *name, long *data)
504{
505	quad_t tmp;
506	int rval;
507
508	rval = getenv_quad(name, &tmp);
509	if (rval)
510		*data = (long) tmp;
511	return (rval);
512}
513
514/*
515 * Return an unsigned long value from an environment variable.
516 */
517int
518getenv_ulong(const char *name, unsigned long *data)
519{
520	quad_t tmp;
521	int rval;
522
523	rval = getenv_quad(name, &tmp);
524	if (rval)
525		*data = (unsigned long) tmp;
526	return (rval);
527}
528
529/*
530 * Return a quad_t value from an environment variable.
531 */
532int
533getenv_quad(const char *name, quad_t *data)
534{
535	char	*value;
536	char	*vtp;
537	quad_t	iv;
538
539	value = getenv(name);
540	if (value == NULL)
541		return (0);
542	iv = strtoq(value, &vtp, 0);
543	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
544		freeenv(value);
545		return (0);
546	}
547	switch (vtp[0]) {
548	case 't': case 'T':
549		iv *= 1024;
550	case 'g': case 'G':
551		iv *= 1024;
552	case 'm': case 'M':
553		iv *= 1024;
554	case 'k': case 'K':
555		iv *= 1024;
556	case '\0':
557		break;
558	default:
559		freeenv(value);
560		return (0);
561	}
562	*data = iv;
563	freeenv(value);
564	return (1);
565}
566
567/*
568 * Find the next entry after the one which (cp) falls within, return a
569 * pointer to its start or NULL if there are no more.
570 */
571static char *
572kernenv_next(char *cp)
573{
574
575	if (cp != NULL) {
576		while (*cp != 0)
577			cp++;
578		cp++;
579		if (*cp == 0)
580			cp = NULL;
581	}
582	return (cp);
583}
584
585void
586tunable_int_init(void *data)
587{
588	struct tunable_int *d = (struct tunable_int *)data;
589
590	TUNABLE_INT_FETCH(d->path, d->var);
591}
592
593void
594tunable_long_init(void *data)
595{
596	struct tunable_long *d = (struct tunable_long *)data;
597
598	TUNABLE_LONG_FETCH(d->path, d->var);
599}
600
601void
602tunable_ulong_init(void *data)
603{
604	struct tunable_ulong *d = (struct tunable_ulong *)data;
605
606	TUNABLE_ULONG_FETCH(d->path, d->var);
607}
608
609void
610tunable_quad_init(void *data)
611{
612	struct tunable_quad *d = (struct tunable_quad *)data;
613
614	TUNABLE_QUAD_FETCH(d->path, d->var);
615}
616
617void
618tunable_str_init(void *data)
619{
620	struct tunable_str *d = (struct tunable_str *)data;
621
622	TUNABLE_STR_FETCH(d->path, d->var, d->size);
623}
624