kern_environment.c revision 164033 
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 164033 2006-11-06 13:42:10Z rwatson $");
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
73 * since SYSINITS are single threaded.
74 */
75int	dynamic_kenv = 0;
76
77#define KENV_CHECK	if (!dynamic_kenv) \
78			    panic("%s: called before SI_SUB_KMEM", __func__)
79
80int
81kenv(td, uap)
82	struct thread *td;
83	struct kenv_args /* {
84		int what;
85		const char *name;
86		char *value;
87		int len;
88	} */ *uap;
89{
90	char *name, *value, *buffer = NULL;
91	size_t len, done, needed;
92	int error, i;
93
94	KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = 0"));
95
96	error = 0;
97	if (uap->what == KENV_DUMP) {
98#ifdef MAC
99		error = mac_check_kenv_dump(td->td_ucred);
100		if (error)
101			return (error);
102#endif
103		done = needed = 0;
104		if (uap->len > 0 && uap->value != NULL)
105			buffer = malloc(uap->len, M_TEMP, M_WAITOK|M_ZERO);
106		mtx_lock(&kenv_lock);
107		for (i = 0; kenvp[i] != NULL; i++) {
108			len = strlen(kenvp[i]) + 1;
109			needed += len;
110			len = min(len, uap->len - done);
111			/*
112			 * If called with a NULL or insufficiently large
113			 * buffer, just keep computing the required size.
114			 */
115			if (uap->value != NULL && buffer != NULL && len > 0) {
116				bcopy(kenvp[i], buffer + done, len);
117				done += len;
118			}
119		}
120		mtx_unlock(&kenv_lock);
121		if (buffer != NULL) {
122			error = copyout(buffer, uap->value, done);
123			free(buffer, M_TEMP);
124		}
125		td->td_retval[0] = ((done == needed) ? 0 : needed);
126		return (error);
127	}
128
129	switch (uap->what) {
130	case KENV_SET:
131		error = priv_check(td, PRIV_KENV_SET);
132		if (error)
133			return (error);
134		break;
135
136	case KENV_UNSET:
137		error = priv_check(td, PRIV_KENV_UNSET);
138		if (error)
139			return (error);
140		break;
141	}
142
143	name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
144
145	error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
146	if (error)
147		goto done;
148
149	switch (uap->what) {
150	case KENV_GET:
151#ifdef MAC
152		error = mac_check_kenv_get(td->td_ucred, name);
153		if (error)
154			goto done;
155#endif
156		value = getenv(name);
157		if (value == NULL) {
158			error = ENOENT;
159			goto done;
160		}
161		len = strlen(value) + 1;
162		if (len > uap->len)
163			len = uap->len;
164		error = copyout(value, uap->value, len);
165		freeenv(value);
166		if (error)
167			goto done;
168		td->td_retval[0] = len;
169		break;
170	case KENV_SET:
171		len = uap->len;
172		if (len < 1) {
173			error = EINVAL;
174			goto done;
175		}
176		if (len > KENV_MVALLEN)
177			len = KENV_MVALLEN;
178		value = malloc(len, M_TEMP, M_WAITOK);
179		error = copyinstr(uap->value, value, len, NULL);
180		if (error) {
181			free(value, M_TEMP);
182			goto done;
183		}
184#ifdef MAC
185		error = mac_check_kenv_set(td->td_ucred, name, value);
186		if (error == 0)
187#endif
188			setenv(name, value);
189		free(value, M_TEMP);
190		break;
191	case KENV_UNSET:
192#ifdef MAC
193		error = mac_check_kenv_unset(td->td_ucred, name);
194		if (error)
195			goto done;
196#endif
197		error = unsetenv(name);
198		if (error)
199			error = ENOENT;
200		break;
201	default:
202		error = EINVAL;
203		break;
204	}
205done:
206	free(name, M_TEMP);
207	return (error);
208}
209
210/*
211 * Setup the dynamic kernel environment.
212 */
213static void
214init_dynamic_kenv(void *data __unused)
215{
216	char *cp;
217	int len, i;
218
219	kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
220		M_WAITOK | M_ZERO);
221	i = 0;
222	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
223		len = strlen(cp) + 1;
224		if (i < KENV_SIZE) {
225			kenvp[i] = malloc(len, M_KENV, M_WAITOK);
226			strcpy(kenvp[i++], cp);
227		} else
228			printf(
229			    "WARNING: too many kenv strings, ignoring %s\n",
230			    cp);
231	}
232	kenvp[i] = NULL;
233
234	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
235	dynamic_kenv = 1;
236}
237SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
238
239void
240freeenv(char *env)
241{
242
243	if (dynamic_kenv)
244		free(env, M_KENV);
245}
246
247/*
248 * Internal functions for string lookup.
249 */
250static char *
251_getenv_dynamic(const char *name, int *idx)
252{
253	char *cp;
254	int len, i;
255
256	mtx_assert(&kenv_lock, MA_OWNED);
257	len = strlen(name);
258	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
259		if ((strncmp(cp, name, len) == 0) &&
260		    (cp[len] == '=')) {
261			if (idx != NULL)
262				*idx = i;
263			return (cp + len + 1);
264		}
265	}
266	return (NULL);
267}
268
269static char *
270_getenv_static(const char *name)
271{
272	char *cp, *ep;
273	int len;
274
275	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
276		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
277			;
278		if (*ep != '=')
279			continue;
280		len = ep - cp;
281		ep++;
282		if (!strncmp(name, cp, len) && name[len] == 0)
283			return (ep);
284	}
285	return (NULL);
286}
287
288/*
289 * Look up an environment variable by name.
290 * Return a pointer to the string if found.
291 * The pointer has to be freed with freeenv()
292 * after use.
293 */
294char *
295getenv(const char *name)
296{
297	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
298	char *ret, *cp;
299	int len;
300
301	if (dynamic_kenv) {
302		mtx_lock(&kenv_lock);
303		cp = _getenv_dynamic(name, NULL);
304		if (cp != NULL) {
305			strcpy(buf, cp);
306			mtx_unlock(&kenv_lock);
307			len = strlen(buf) + 1;
308			ret = malloc(len, M_KENV, M_WAITOK);
309			strcpy(ret, buf);
310		} else {
311			mtx_unlock(&kenv_lock);
312			ret = NULL;
313		}
314	} else
315		ret = _getenv_static(name);
316	return (ret);
317}
318
319/*
320 * Test if an environment variable is defined.
321 */
322int
323testenv(const char *name)
324{
325	char *cp;
326
327	if (dynamic_kenv) {
328		mtx_lock(&kenv_lock);
329		cp = _getenv_dynamic(name, NULL);
330		mtx_unlock(&kenv_lock);
331	} else
332		cp = _getenv_static(name);
333	if (cp != NULL)
334		return (1);
335	return (0);
336}
337
338/*
339 * Set an environment variable by name.
340 */
341int
342setenv(const char *name, const char *value)
343{
344	char *buf, *cp, *oldenv;
345	int namelen, vallen, i;
346
347	KENV_CHECK;
348
349	namelen = strlen(name) + 1;
350	if (namelen > KENV_MNAMELEN)
351		return (-1);
352	vallen = strlen(value) + 1;
353	if (vallen > KENV_MVALLEN)
354		return (-1);
355	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
356	sprintf(buf, "%s=%s", name, value);
357
358	mtx_lock(&kenv_lock);
359	cp = _getenv_dynamic(name, &i);
360	if (cp != NULL) {
361		oldenv = kenvp[i];
362		kenvp[i] = buf;
363		mtx_unlock(&kenv_lock);
364		free(oldenv, M_KENV);
365	} else {
366		/* We add the option if it wasn't found */
367		for (i = 0; (cp = kenvp[i]) != NULL; i++)
368			;
369
370		/* Bounds checking */
371		if (i < 0 || i >= KENV_SIZE) {
372			free(buf, M_KENV);
373			mtx_unlock(&kenv_lock);
374			return (-1);
375		}
376
377		kenvp[i] = buf;
378		kenvp[i + 1] = NULL;
379		mtx_unlock(&kenv_lock);
380	}
381	return (0);
382}
383
384/*
385 * Unset an environment variable string.
386 */
387int
388unsetenv(const char *name)
389{
390	char *cp, *oldenv;
391	int i, j;
392
393	KENV_CHECK;
394
395	mtx_lock(&kenv_lock);
396	cp = _getenv_dynamic(name, &i);
397	if (cp != NULL) {
398		oldenv = kenvp[i];
399		for (j = i + 1; kenvp[j] != NULL; j++)
400			kenvp[i++] = kenvp[j];
401		kenvp[i] = NULL;
402		mtx_unlock(&kenv_lock);
403		free(oldenv, M_KENV);
404		return (0);
405	}
406	mtx_unlock(&kenv_lock);
407	return (-1);
408}
409
410/*
411 * Return a string value from an environment variable.
412 */
413int
414getenv_string(const char *name, char *data, int size)
415{
416	char *tmp;
417
418	tmp = getenv(name);
419	if (tmp != NULL) {
420		strlcpy(data, tmp, size);
421		freeenv(tmp);
422		return (1);
423	} else
424		return (0);
425}
426
427/*
428 * Return an integer value from an environment variable.
429 */
430int
431getenv_int(const char *name, int *data)
432{
433	quad_t tmp;
434	int rval;
435
436	rval = getenv_quad(name, &tmp);
437	if (rval)
438		*data = (int) tmp;
439	return (rval);
440}
441
442/*
443 * Return a long value from an environment variable.
444 */
445long
446getenv_long(const char *name, long *data)
447{
448	quad_t tmp;
449	long rval;
450
451	rval = getenv_quad(name, &tmp);
452	if (rval)
453		*data = (long) tmp;
454	return (rval);
455}
456
457/*
458 * Return an unsigned long value from an environment variable.
459 */
460unsigned long
461getenv_ulong(const char *name, unsigned long *data)
462{
463	quad_t tmp;
464	long rval;
465
466	rval = getenv_quad(name, &tmp);
467	if (rval)
468		*data = (unsigned long) tmp;
469	return (rval);
470}
471
472/*
473 * Return a quad_t value from an environment variable.
474 */
475int
476getenv_quad(const char *name, quad_t *data)
477{
478	char	*value;
479	char	*vtp;
480	quad_t	iv;
481
482	value = getenv(name);
483	if (value == NULL)
484		return (0);
485	iv = strtoq(value, &vtp, 0);
486	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
487		freeenv(value);
488		return (0);
489	}
490	switch (vtp[0]) {
491	case 't': case 'T':
492		iv *= 1024;
493	case 'g': case 'G':
494		iv *= 1024;
495	case 'm': case 'M':
496		iv *= 1024;
497	case 'k': case 'K':
498		iv *= 1024;
499	case '\0':
500		break;
501	default:
502		freeenv(value);
503		return (0);
504	}
505	*data = iv;
506	freeenv(value);
507	return (1);
508}
509
510/*
511 * Find the next entry after the one which (cp) falls within, return a
512 * pointer to its start or NULL if there are no more.
513 */
514static char *
515kernenv_next(char *cp)
516{
517
518	if (cp != NULL) {
519		while (*cp != 0)
520			cp++;
521		cp++;
522		if (*cp == 0)
523			cp = NULL;
524	}
525	return (cp);
526}
527
528void
529tunable_int_init(void *data)
530{
531	struct tunable_int *d = (struct tunable_int *)data;
532
533	TUNABLE_INT_FETCH(d->path, d->var);
534}
535
536void
537tunable_long_init(void *data)
538{
539	struct tunable_long *d = (struct tunable_long *)data;
540
541	TUNABLE_LONG_FETCH(d->path, d->var);
542}
543
544void
545tunable_ulong_init(void *data)
546{
547	struct tunable_ulong *d = (struct tunable_ulong *)data;
548
549	TUNABLE_ULONG_FETCH(d->path, d->var);
550}
551
552void
553tunable_str_init(void *data)
554{
555	struct tunable_str *d = (struct tunable_str *)data;
556
557	TUNABLE_STR_FETCH(d->path, d->var, d->size);
558}
559