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 kern_getenv()/freeenv() kern_setenv() kern_unsetenv() testenv() for
34 * the kernel.
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/11.2/sys/kern/kern_environment.c 298025 2016-04-15 03:09:55Z imp $");
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 = kern_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 kern_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 = kern_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 /*
214 * Populate the initial kernel environment.
215 *
216 * This is called very early in MD startup, either to provide a copy of the
217 * environment obtained from a boot loader, or to provide an empty buffer into
218 * which MD code can store an initial environment using kern_setenv() calls.
219 *
220 * When a copy of an initial environment is passed in, we start by scanning that
221 * env for overrides to the compiled-in envmode and hintmode variables.
222 *
223 * If the global envmode is 1, the environment is initialized from the global
224 * static_env[], regardless of the arguments passed. This implements the env
225 * keyword described in config(5). In this case env_pos is set to env_len,
226 * causing kern_setenv() to return -1 (if len > 0) or panic (if len == 0) until
227 * the dynamic environment is available. The envmode and static_env variables
228 * are defined in env.c which is generated by config(8).
229 *
230 * If len is non-zero, the caller is providing an empty buffer. The caller will
231 * subsequently use kern_setenv() to add up to len bytes of initial environment
232 * before the dynamic environment is available.
233 *
234 * If len is zero, the caller is providing a pre-loaded buffer containing
235 * environment strings. Additional strings cannot be added until the dynamic
236 * environment is available. The memory pointed to must remain stable at least
237 * until sysinit runs init_dynamic_kenv(). If no initial environment is
238 * available from the boot loader, passing a NULL pointer allows the static_env
239 * to be installed if it is configured.
240 */
241 void
242 init_static_kenv(char *buf, size_t len)
243 {
244 char *cp;
245
246 for (cp = buf; cp != NULL && cp[0] != '\0'; cp += strlen(cp) + 1) {
247 if (strcmp(cp, "static_env.disabled=1") == 0)
248 envmode = 0;
249 if (strcmp(cp, "static_hints.disabled=1") == 0)
250 hintmode = 0;
251 }
252
253 if (envmode == 1) {
254 kern_envp = static_env;
255 env_len = len;
256 env_pos = len;
257 } else {
258 kern_envp = buf;
259 env_len = len;
260 env_pos = 0;
261 }
262 }
263
264 /*
265 * Setup the dynamic kernel environment.
266 */
267 static void
268 init_dynamic_kenv(void *data __unused)
269 {
270 char *cp, *cpnext;
271 size_t len;
272 int i;
273
274 kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
275 M_WAITOK | M_ZERO);
276 i = 0;
277 if (kern_envp && *kern_envp != '\0') {
278 for (cp = kern_envp; cp != NULL; cp = cpnext) {
279 cpnext = kernenv_next(cp);
280 len = strlen(cp) + 1;
281 if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
282 printf(
283 "WARNING: too long kenv string, ignoring %s\n",
284 cp);
285 continue;
286 }
287 if (i < KENV_SIZE) {
288 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
289 strcpy(kenvp[i++], cp);
290 memset(cp, 0, strlen(cp));
291 } else
292 printf(
293 "WARNING: too many kenv strings, ignoring %s\n",
294 cp);
295 }
296 }
297 kenvp[i] = NULL;
298
299 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
300 dynamic_kenv = 1;
301 }
302 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
303
304 void
305 freeenv(char *env)
306 {
307
308 if (dynamic_kenv && env != NULL) {
309 memset(env, 0, strlen(env));
310 free(env, M_KENV);
311 }
312 }
313
314 /*
315 * Internal functions for string lookup.
316 */
317 static char *
318 _getenv_dynamic(const char *name, int *idx)
319 {
320 char *cp;
321 int len, i;
322
323 mtx_assert(&kenv_lock, MA_OWNED);
324 len = strlen(name);
325 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
326 if ((strncmp(cp, name, len) == 0) &&
327 (cp[len] == '=')) {
328 if (idx != NULL)
329 *idx = i;
330 return (cp + len + 1);
331 }
332 }
333 return (NULL);
334 }
335
336 static char *
337 _getenv_static(const char *name)
338 {
339 char *cp, *ep;
340 int len;
341
342 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
343 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
344 ;
345 if (*ep != '=')
346 continue;
347 len = ep - cp;
348 ep++;
349 if (!strncmp(name, cp, len) && name[len] == 0)
350 return (ep);
351 }
352 return (NULL);
353 }
354
355 /*
356 * Look up an environment variable by name.
357 * Return a pointer to the string if found.
358 * The pointer has to be freed with freeenv()
359 * after use.
360 */
361 char *
362 kern_getenv(const char *name)
363 {
364 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
365 char *ret;
366
367 if (dynamic_kenv) {
368 if (getenv_string(name, buf, sizeof(buf))) {
369 ret = strdup(buf, M_KENV);
370 } else {
371 ret = NULL;
372 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
373 "getenv");
374 }
375 } else
376 ret = _getenv_static(name);
377 return (ret);
378 }
379
380 /*
381 * Test if an environment variable is defined.
382 */
383 int
384 testenv(const char *name)
385 {
386 char *cp;
387
388 if (dynamic_kenv) {
389 mtx_lock(&kenv_lock);
390 cp = _getenv_dynamic(name, NULL);
391 mtx_unlock(&kenv_lock);
392 } else
393 cp = _getenv_static(name);
394 if (cp != NULL)
395 return (1);
396 return (0);
397 }
398
399 static int
400 setenv_static(const char *name, const char *value)
401 {
402 int len;
403
404 if (env_pos >= env_len)
405 return (-1);
406
407 /* Check space for x=y and two nuls */
408 len = strlen(name) + strlen(value);
409 if (len + 3 < env_len - env_pos) {
410 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
411 env_pos += len+1;
412 kern_envp[env_pos] = '\0';
413 return (0);
414 } else
415 return (-1);
416
417 }
418
419 /*
420 * Set an environment variable by name.
421 */
422 int
423 kern_setenv(const char *name, const char *value)
424 {
425 char *buf, *cp, *oldenv;
426 int namelen, vallen, i;
427
428 if (dynamic_kenv == 0 && env_len > 0)
429 return (setenv_static(name, value));
430
431 KENV_CHECK;
432
433 namelen = strlen(name) + 1;
434 if (namelen > KENV_MNAMELEN + 1)
435 return (-1);
436 vallen = strlen(value) + 1;
437 if (vallen > KENV_MVALLEN + 1)
438 return (-1);
439 buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
440 sprintf(buf, "%s=%s", name, value);
441
442 mtx_lock(&kenv_lock);
443 cp = _getenv_dynamic(name, &i);
444 if (cp != NULL) {
445 oldenv = kenvp[i];
446 kenvp[i] = buf;
447 mtx_unlock(&kenv_lock);
448 free(oldenv, M_KENV);
449 } else {
450 /* We add the option if it wasn't found */
451 for (i = 0; (cp = kenvp[i]) != NULL; i++)
452 ;
453
454 /* Bounds checking */
455 if (i < 0 || i >= KENV_SIZE) {
456 free(buf, M_KENV);
457 mtx_unlock(&kenv_lock);
458 return (-1);
459 }
460
461 kenvp[i] = buf;
462 kenvp[i + 1] = NULL;
463 mtx_unlock(&kenv_lock);
464 }
465 return (0);
466 }
467
468 /*
469 * Unset an environment variable string.
470 */
471 int
472 kern_unsetenv(const char *name)
473 {
474 char *cp, *oldenv;
475 int i, j;
476
477 KENV_CHECK;
478
479 mtx_lock(&kenv_lock);
480 cp = _getenv_dynamic(name, &i);
481 if (cp != NULL) {
482 oldenv = kenvp[i];
483 for (j = i + 1; kenvp[j] != NULL; j++)
484 kenvp[i++] = kenvp[j];
485 kenvp[i] = NULL;
486 mtx_unlock(&kenv_lock);
487 memset(oldenv, 0, strlen(oldenv));
488 free(oldenv, M_KENV);
489 return (0);
490 }
491 mtx_unlock(&kenv_lock);
492 return (-1);
493 }
494
495 /*
496 * Return a string value from an environment variable.
497 */
498 int
499 getenv_string(const char *name, char *data, int size)
500 {
501 char *cp;
502
503 if (dynamic_kenv) {
504 mtx_lock(&kenv_lock);
505 cp = _getenv_dynamic(name, NULL);
506 if (cp != NULL)
507 strlcpy(data, cp, size);
508 mtx_unlock(&kenv_lock);
509 } else {
510 cp = _getenv_static(name);
511 if (cp != NULL)
512 strlcpy(data, cp, size);
513 }
514 return (cp != NULL);
515 }
516
517 /*
518 * Return an integer value from an environment variable.
519 */
520 int
521 getenv_int(const char *name, int *data)
522 {
523 quad_t tmp;
524 int rval;
525
526 rval = getenv_quad(name, &tmp);
527 if (rval)
528 *data = (int) tmp;
529 return (rval);
530 }
531
532 /*
533 * Return an unsigned integer value from an environment variable.
534 */
535 int
536 getenv_uint(const char *name, unsigned int *data)
537 {
538 quad_t tmp;
539 int rval;
540
541 rval = getenv_quad(name, &tmp);
542 if (rval)
543 *data = (unsigned int) tmp;
544 return (rval);
545 }
546
547 /*
548 * Return an int64_t value from an environment variable.
549 */
550 int
551 getenv_int64(const char *name, int64_t *data)
552 {
553 quad_t tmp;
554 int64_t rval;
555
556 rval = getenv_quad(name, &tmp);
557 if (rval)
558 *data = (int64_t) tmp;
559 return (rval);
560 }
561
562 /*
563 * Return an uint64_t value from an environment variable.
564 */
565 int
566 getenv_uint64(const char *name, uint64_t *data)
567 {
568 quad_t tmp;
569 uint64_t rval;
570
571 rval = getenv_quad(name, &tmp);
572 if (rval)
573 *data = (uint64_t) tmp;
574 return (rval);
575 }
576
577 /*
578 * Return a long value from an environment variable.
579 */
580 int
581 getenv_long(const char *name, long *data)
582 {
583 quad_t tmp;
584 int rval;
585
586 rval = getenv_quad(name, &tmp);
587 if (rval)
588 *data = (long) tmp;
589 return (rval);
590 }
591
592 /*
593 * Return an unsigned long value from an environment variable.
594 */
595 int
596 getenv_ulong(const char *name, unsigned long *data)
597 {
598 quad_t tmp;
599 int rval;
600
601 rval = getenv_quad(name, &tmp);
602 if (rval)
603 *data = (unsigned long) tmp;
604 return (rval);
605 }
606
607 /*
608 * Return a quad_t value from an environment variable.
609 */
610 int
611 getenv_quad(const char *name, quad_t *data)
612 {
613 char value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
614 char *vtp;
615 quad_t iv;
616
617 if (!getenv_string(name, value, sizeof(value)))
618 return (0);
619 iv = strtoq(value, &vtp, 0);
620 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
621 return (0);
622 switch (vtp[0]) {
623 case 't': case 'T':
624 iv *= 1024;
625 case 'g': case 'G':
626 iv *= 1024;
627 case 'm': case 'M':
628 iv *= 1024;
629 case 'k': case 'K':
630 iv *= 1024;
631 case '\0':
632 break;
633 default:
634 return (0);
635 }
636 *data = iv;
637 return (1);
638 }
639
640 /*
641 * Find the next entry after the one which (cp) falls within, return a
642 * pointer to its start or NULL if there are no more.
643 */
644 static char *
645 kernenv_next(char *cp)
646 {
647
648 if (cp != NULL) {
649 while (*cp != 0)
650 cp++;
651 cp++;
652 if (*cp == 0)
653 cp = NULL;
654 }
655 return (cp);
656 }
657
658 void
659 tunable_int_init(void *data)
660 {
661 struct tunable_int *d = (struct tunable_int *)data;
662
663 TUNABLE_INT_FETCH(d->path, d->var);
664 }
665
666 void
667 tunable_long_init(void *data)
668 {
669 struct tunable_long *d = (struct tunable_long *)data;
670
671 TUNABLE_LONG_FETCH(d->path, d->var);
672 }
673
674 void
675 tunable_ulong_init(void *data)
676 {
677 struct tunable_ulong *d = (struct tunable_ulong *)data;
678
679 TUNABLE_ULONG_FETCH(d->path, d->var);
680 }
681
682 void
683 tunable_int64_init(void *data)
684 {
685 struct tunable_int64 *d = (struct tunable_int64 *)data;
686
687 TUNABLE_INT64_FETCH(d->path, d->var);
688 }
689
690 void
691 tunable_uint64_init(void *data)
692 {
693 struct tunable_uint64 *d = (struct tunable_uint64 *)data;
694
695 TUNABLE_UINT64_FETCH(d->path, d->var);
696 }
697
698 void
699 tunable_quad_init(void *data)
700 {
701 struct tunable_quad *d = (struct tunable_quad *)data;
702
703 TUNABLE_QUAD_FETCH(d->path, d->var);
704 }
705
706 void
707 tunable_str_init(void *data)
708 {
709 struct tunable_str *d = (struct tunable_str *)data;
710
711 TUNABLE_STR_FETCH(d->path, d->var, d->size);
712 }
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