xref: /freebsd/sys/kern/kern_environment.c (revision 09d325677d53a12c79a43664ff29871e92247629)
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("$FreeBSD$");
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 
57 static 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 */
62 char		*kern_envp;
63 static int	env_len;
64 static int	env_pos;
65 static char	*kernenv_next(char *);
66 
67 /* dynamic environment variables */
68 char		**kenvp;
69 struct mtx	kenv_lock;
70 
71 /*
72  * No need to protect this with a mutex since SYSINITS are single threaded.
73  */
74 int	dynamic_kenv = 0;
75 
76 #define KENV_CHECK	if (!dynamic_kenv) \
77 			    panic("%s: called before SI_SUB_KMEM", __func__)
78 
79 int
80 sys_kenv(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 + 1, M_TEMP, M_WAITOK);
147 
148 	error = copyinstr(uap->name, name, KENV_MNAMELEN + 1, 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 + 1)
180 			len = KENV_MVALLEN + 1;
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 	}
208 done:
209 	free(name, M_TEMP);
210 	return (error);
211 }
212 
213 void
214 init_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  */
224 static void
225 init_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 	if (kern_envp && *kern_envp != '\0') {
235 		for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
236 			len = strlen(cp) + 1;
237 			if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
238 				printf(
239 				"WARNING: too long kenv string, ignoring %s\n",
240 				    cp);
241 				continue;
242 			}
243 			if (i < KENV_SIZE) {
244 				kenvp[i] = malloc(len, M_KENV, M_WAITOK);
245 				strcpy(kenvp[i++], cp);
246 			} else
247 				printf(
248 				"WARNING: too many kenv strings, ignoring %s\n",
249 				    cp);
250 		}
251 	}
252 	kenvp[i] = NULL;
253 
254 	mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
255 	dynamic_kenv = 1;
256 }
257 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
258 
259 void
260 freeenv(char *env)
261 {
262 
263 	if (dynamic_kenv)
264 		free(env, M_KENV);
265 }
266 
267 /*
268  * Internal functions for string lookup.
269  */
270 static char *
271 _getenv_dynamic(const char *name, int *idx)
272 {
273 	char *cp;
274 	int len, i;
275 
276 	mtx_assert(&kenv_lock, MA_OWNED);
277 	len = strlen(name);
278 	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
279 		if ((strncmp(cp, name, len) == 0) &&
280 		    (cp[len] == '=')) {
281 			if (idx != NULL)
282 				*idx = i;
283 			return (cp + len + 1);
284 		}
285 	}
286 	return (NULL);
287 }
288 
289 static char *
290 _getenv_static(const char *name)
291 {
292 	char *cp, *ep;
293 	int len;
294 
295 	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
296 		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
297 			;
298 		if (*ep != '=')
299 			continue;
300 		len = ep - cp;
301 		ep++;
302 		if (!strncmp(name, cp, len) && name[len] == 0)
303 			return (ep);
304 	}
305 	return (NULL);
306 }
307 
308 /*
309  * Look up an environment variable by name.
310  * Return a pointer to the string if found.
311  * The pointer has to be freed with freeenv()
312  * after use.
313  */
314 char *
315 getenv(const char *name)
316 {
317 	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
318 	char *ret;
319 
320 	if (dynamic_kenv) {
321 		if (getenv_string(name, buf, sizeof(buf))) {
322 			ret = strdup(buf, M_KENV);
323 		} else {
324 			ret = NULL;
325 			WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
326 			    "getenv");
327 		}
328 	} else
329 		ret = _getenv_static(name);
330 	return (ret);
331 }
332 
333 /*
334  * Test if an environment variable is defined.
335  */
336 int
337 testenv(const char *name)
338 {
339 	char *cp;
340 
341 	if (dynamic_kenv) {
342 		mtx_lock(&kenv_lock);
343 		cp = _getenv_dynamic(name, NULL);
344 		mtx_unlock(&kenv_lock);
345 	} else
346 		cp = _getenv_static(name);
347 	if (cp != NULL)
348 		return (1);
349 	return (0);
350 }
351 
352 static int
353 setenv_static(const char *name, const char *value)
354 {
355 	int len;
356 
357 	if (env_pos >= env_len)
358 		return (-1);
359 
360 	/* Check space for x=y and two nuls */
361 	len = strlen(name) + strlen(value);
362 	if (len + 3 < env_len - env_pos) {
363 		len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
364 		env_pos += len+1;
365 		kern_envp[env_pos] = '\0';
366 		return (0);
367 	} else
368 		return (-1);
369 
370 }
371 
372 /*
373  * Set an environment variable by name.
374  */
375 int
376 setenv(const char *name, const char *value)
377 {
378 	char *buf, *cp, *oldenv;
379 	int namelen, vallen, i;
380 
381 	if (dynamic_kenv == 0 && env_len > 0)
382 		return (setenv_static(name, value));
383 
384 	KENV_CHECK;
385 
386 	namelen = strlen(name) + 1;
387 	if (namelen > KENV_MNAMELEN + 1)
388 		return (-1);
389 	vallen = strlen(value) + 1;
390 	if (vallen > KENV_MVALLEN + 1)
391 		return (-1);
392 	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
393 	sprintf(buf, "%s=%s", name, value);
394 
395 	mtx_lock(&kenv_lock);
396 	cp = _getenv_dynamic(name, &i);
397 	if (cp != NULL) {
398 		oldenv = kenvp[i];
399 		kenvp[i] = buf;
400 		mtx_unlock(&kenv_lock);
401 		free(oldenv, M_KENV);
402 	} else {
403 		/* We add the option if it wasn't found */
404 		for (i = 0; (cp = kenvp[i]) != NULL; i++)
405 			;
406 
407 		/* Bounds checking */
408 		if (i < 0 || i >= KENV_SIZE) {
409 			free(buf, M_KENV);
410 			mtx_unlock(&kenv_lock);
411 			return (-1);
412 		}
413 
414 		kenvp[i] = buf;
415 		kenvp[i + 1] = NULL;
416 		mtx_unlock(&kenv_lock);
417 	}
418 	return (0);
419 }
420 
421 /*
422  * Unset an environment variable string.
423  */
424 int
425 unsetenv(const char *name)
426 {
427 	char *cp, *oldenv;
428 	int i, j;
429 
430 	KENV_CHECK;
431 
432 	mtx_lock(&kenv_lock);
433 	cp = _getenv_dynamic(name, &i);
434 	if (cp != NULL) {
435 		oldenv = kenvp[i];
436 		for (j = i + 1; kenvp[j] != NULL; j++)
437 			kenvp[i++] = kenvp[j];
438 		kenvp[i] = NULL;
439 		mtx_unlock(&kenv_lock);
440 		free(oldenv, M_KENV);
441 		return (0);
442 	}
443 	mtx_unlock(&kenv_lock);
444 	return (-1);
445 }
446 
447 /*
448  * Return a string value from an environment variable.
449  */
450 int
451 getenv_string(const char *name, char *data, int size)
452 {
453 	char *cp;
454 
455 	if (dynamic_kenv) {
456 		mtx_lock(&kenv_lock);
457 		cp = _getenv_dynamic(name, NULL);
458 		if (cp != NULL)
459 			strlcpy(data, cp, size);
460 		mtx_unlock(&kenv_lock);
461 	} else {
462 		cp = _getenv_static(name);
463 		if (cp != NULL)
464 			strlcpy(data, cp, size);
465 	}
466 	return (cp != NULL);
467 }
468 
469 /*
470  * Return an integer value from an environment variable.
471  */
472 int
473 getenv_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  */
487 int
488 getenv_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  */
502 int
503 getenv_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  */
517 int
518 getenv_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  */
532 int
533 getenv_quad(const char *name, quad_t *data)
534 {
535 	char	value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
536 	char	*vtp;
537 	quad_t	iv;
538 
539 	if (!getenv_string(name, value, sizeof(value)))
540 		return (0);
541 	iv = strtoq(value, &vtp, 0);
542 	if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
543 		return (0);
544 	switch (vtp[0]) {
545 	case 't': case 'T':
546 		iv *= 1024;
547 	case 'g': case 'G':
548 		iv *= 1024;
549 	case 'm': case 'M':
550 		iv *= 1024;
551 	case 'k': case 'K':
552 		iv *= 1024;
553 	case '\0':
554 		break;
555 	default:
556 		return (0);
557 	}
558 	*data = iv;
559 	return (1);
560 }
561 
562 /*
563  * Find the next entry after the one which (cp) falls within, return a
564  * pointer to its start or NULL if there are no more.
565  */
566 static char *
567 kernenv_next(char *cp)
568 {
569 
570 	if (cp != NULL) {
571 		while (*cp != 0)
572 			cp++;
573 		cp++;
574 		if (*cp == 0)
575 			cp = NULL;
576 	}
577 	return (cp);
578 }
579 
580 void
581 tunable_int_init(void *data)
582 {
583 	struct tunable_int *d = (struct tunable_int *)data;
584 
585 	TUNABLE_INT_FETCH(d->path, d->var);
586 }
587 
588 void
589 tunable_long_init(void *data)
590 {
591 	struct tunable_long *d = (struct tunable_long *)data;
592 
593 	TUNABLE_LONG_FETCH(d->path, d->var);
594 }
595 
596 void
597 tunable_ulong_init(void *data)
598 {
599 	struct tunable_ulong *d = (struct tunable_ulong *)data;
600 
601 	TUNABLE_ULONG_FETCH(d->path, d->var);
602 }
603 
604 void
605 tunable_quad_init(void *data)
606 {
607 	struct tunable_quad *d = (struct tunable_quad *)data;
608 
609 	TUNABLE_QUAD_FETCH(d->path, d->var);
610 }
611 
612 void
613 tunable_str_init(void *data)
614 {
615 	struct tunable_str *d = (struct tunable_str *)data;
616 
617 	TUNABLE_STR_FETCH(d->path, d->var, d->size);
618 }
619