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: releng/10.4/sys/kern/kern_environment.c 294683 2016-01-24 21:04:06Z ian $");
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 /*
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 * If the global envmode is 1, the environment is initialized from the global
221 * static_env[], regardless of the arguments passed. This implements the env
222 * keyword described in config(5). In this case env_pos is set to env_len,
223 * causing kern_setenv() to return -1 (if len > 0) or panic (if len == 0) until
224 * the dynamic environment is available. The envmode and static_env variables
225 * are defined in env.c which is generated by config(8).
226 *
227 * If len is non-zero, the caller is providing an empty buffer. The caller will
228 * subsequently use kern_setenv() to add up to len bytes of initial environment
229 * before the dynamic environment is available.
230 *
231 * If len is zero, the caller is providing a pre-loaded buffer containing
232 * environment strings. Additional strings cannot be added until the dynamic
233 * environment is available. The memory pointed to must remain stable at least
234 * until sysinit runs init_dynamic_kenv(). If no initial environment is
235 * available from the boot loader, passing a NULL pointer allows the static_env
236 * to be installed if it is configured.
237 */
238 void
239 init_static_kenv(char *buf, size_t len)
240 {
241
242 if (envmode == 1) {
243 kern_envp = static_env;
244 env_len = len;
245 env_pos = len;
246 } else {
247 kern_envp = buf;
248 env_len = len;
249 env_pos = 0;
250 }
251 }
252
253 /*
254 * Setup the dynamic kernel environment.
255 */
256 static void
257 init_dynamic_kenv(void *data __unused)
258 {
259 char *cp;
260 size_t len;
261 int i;
262
263 kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
264 M_WAITOK | M_ZERO);
265 i = 0;
266 if (kern_envp && *kern_envp != '\0') {
267 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
268 len = strlen(cp) + 1;
269 if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
270 printf(
271 "WARNING: too long kenv string, ignoring %s\n",
272 cp);
273 continue;
274 }
275 if (i < KENV_SIZE) {
276 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
277 strcpy(kenvp[i++], cp);
278 } else
279 printf(
280 "WARNING: too many kenv strings, ignoring %s\n",
281 cp);
282 }
283 }
284 kenvp[i] = NULL;
285
286 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
287 dynamic_kenv = 1;
288 }
289 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
290
291 void
292 freeenv(char *env)
293 {
294
295 if (dynamic_kenv)
296 free(env, M_KENV);
297 }
298
299 /*
300 * Internal functions for string lookup.
301 */
302 static char *
303 _getenv_dynamic(const char *name, int *idx)
304 {
305 char *cp;
306 int len, i;
307
308 mtx_assert(&kenv_lock, MA_OWNED);
309 len = strlen(name);
310 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
311 if ((strncmp(cp, name, len) == 0) &&
312 (cp[len] == '=')) {
313 if (idx != NULL)
314 *idx = i;
315 return (cp + len + 1);
316 }
317 }
318 return (NULL);
319 }
320
321 static char *
322 _getenv_static(const char *name)
323 {
324 char *cp, *ep;
325 int len;
326
327 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
328 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
329 ;
330 if (*ep != '=')
331 continue;
332 len = ep - cp;
333 ep++;
334 if (!strncmp(name, cp, len) && name[len] == 0)
335 return (ep);
336 }
337 return (NULL);
338 }
339
340 /*
341 * Look up an environment variable by name.
342 * Return a pointer to the string if found.
343 * The pointer has to be freed with freeenv()
344 * after use.
345 */
346 char *
347 getenv(const char *name)
348 {
349 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
350 char *ret;
351
352 if (dynamic_kenv) {
353 if (getenv_string(name, buf, sizeof(buf))) {
354 ret = strdup(buf, M_KENV);
355 } else {
356 ret = NULL;
357 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
358 "getenv");
359 }
360 } else
361 ret = _getenv_static(name);
362 return (ret);
363 }
364
365 /*
366 * Test if an environment variable is defined.
367 */
368 int
369 testenv(const char *name)
370 {
371 char *cp;
372
373 if (dynamic_kenv) {
374 mtx_lock(&kenv_lock);
375 cp = _getenv_dynamic(name, NULL);
376 mtx_unlock(&kenv_lock);
377 } else
378 cp = _getenv_static(name);
379 if (cp != NULL)
380 return (1);
381 return (0);
382 }
383
384 static int
385 setenv_static(const char *name, const char *value)
386 {
387 int len;
388
389 if (env_pos >= env_len)
390 return (-1);
391
392 /* Check space for x=y and two nuls */
393 len = strlen(name) + strlen(value);
394 if (len + 3 < env_len - env_pos) {
395 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
396 env_pos += len+1;
397 kern_envp[env_pos] = '\0';
398 return (0);
399 } else
400 return (-1);
401
402 }
403
404 /*
405 * Set an environment variable by name.
406 */
407 int
408 setenv(const char *name, const char *value)
409 {
410 char *buf, *cp, *oldenv;
411 int namelen, vallen, i;
412
413 if (dynamic_kenv == 0 && env_len > 0)
414 return (setenv_static(name, value));
415
416 KENV_CHECK;
417
418 namelen = strlen(name) + 1;
419 if (namelen > KENV_MNAMELEN + 1)
420 return (-1);
421 vallen = strlen(value) + 1;
422 if (vallen > KENV_MVALLEN + 1)
423 return (-1);
424 buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
425 sprintf(buf, "%s=%s", name, value);
426
427 mtx_lock(&kenv_lock);
428 cp = _getenv_dynamic(name, &i);
429 if (cp != NULL) {
430 oldenv = kenvp[i];
431 kenvp[i] = buf;
432 mtx_unlock(&kenv_lock);
433 free(oldenv, M_KENV);
434 } else {
435 /* We add the option if it wasn't found */
436 for (i = 0; (cp = kenvp[i]) != NULL; i++)
437 ;
438
439 /* Bounds checking */
440 if (i < 0 || i >= KENV_SIZE) {
441 free(buf, M_KENV);
442 mtx_unlock(&kenv_lock);
443 return (-1);
444 }
445
446 kenvp[i] = buf;
447 kenvp[i + 1] = NULL;
448 mtx_unlock(&kenv_lock);
449 }
450 return (0);
451 }
452
453 /*
454 * Unset an environment variable string.
455 */
456 int
457 unsetenv(const char *name)
458 {
459 char *cp, *oldenv;
460 int i, j;
461
462 KENV_CHECK;
463
464 mtx_lock(&kenv_lock);
465 cp = _getenv_dynamic(name, &i);
466 if (cp != NULL) {
467 oldenv = kenvp[i];
468 for (j = i + 1; kenvp[j] != NULL; j++)
469 kenvp[i++] = kenvp[j];
470 kenvp[i] = NULL;
471 mtx_unlock(&kenv_lock);
472 free(oldenv, M_KENV);
473 return (0);
474 }
475 mtx_unlock(&kenv_lock);
476 return (-1);
477 }
478
479 /*
480 * Return a string value from an environment variable.
481 */
482 int
483 getenv_string(const char *name, char *data, int size)
484 {
485 char *cp;
486
487 if (dynamic_kenv) {
488 mtx_lock(&kenv_lock);
489 cp = _getenv_dynamic(name, NULL);
490 if (cp != NULL)
491 strlcpy(data, cp, size);
492 mtx_unlock(&kenv_lock);
493 } else {
494 cp = _getenv_static(name);
495 if (cp != NULL)
496 strlcpy(data, cp, size);
497 }
498 return (cp != NULL);
499 }
500
501 /*
502 * Return an integer value from an environment variable.
503 */
504 int
505 getenv_int(const char *name, int *data)
506 {
507 quad_t tmp;
508 int rval;
509
510 rval = getenv_quad(name, &tmp);
511 if (rval)
512 *data = (int) tmp;
513 return (rval);
514 }
515
516 /*
517 * Return an unsigned integer value from an environment variable.
518 */
519 int
520 getenv_uint(const char *name, unsigned int *data)
521 {
522 quad_t tmp;
523 int rval;
524
525 rval = getenv_quad(name, &tmp);
526 if (rval)
527 *data = (unsigned int) tmp;
528 return (rval);
529 }
530
531 /*
532 * Return a long value from an environment variable.
533 */
534 int
535 getenv_long(const char *name, long *data)
536 {
537 quad_t tmp;
538 int rval;
539
540 rval = getenv_quad(name, &tmp);
541 if (rval)
542 *data = (long) tmp;
543 return (rval);
544 }
545
546 /*
547 * Return an unsigned long value from an environment variable.
548 */
549 int
550 getenv_ulong(const char *name, unsigned long *data)
551 {
552 quad_t tmp;
553 int rval;
554
555 rval = getenv_quad(name, &tmp);
556 if (rval)
557 *data = (unsigned long) tmp;
558 return (rval);
559 }
560
561 /*
562 * Return a quad_t value from an environment variable.
563 */
564 int
565 getenv_quad(const char *name, quad_t *data)
566 {
567 char value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
568 char *vtp;
569 quad_t iv;
570
571 if (!getenv_string(name, value, sizeof(value)))
572 return (0);
573 iv = strtoq(value, &vtp, 0);
574 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
575 return (0);
576 switch (vtp[0]) {
577 case 't': case 'T':
578 iv *= 1024;
579 case 'g': case 'G':
580 iv *= 1024;
581 case 'm': case 'M':
582 iv *= 1024;
583 case 'k': case 'K':
584 iv *= 1024;
585 case '\0':
586 break;
587 default:
588 return (0);
589 }
590 *data = iv;
591 return (1);
592 }
593
594 /*
595 * Find the next entry after the one which (cp) falls within, return a
596 * pointer to its start or NULL if there are no more.
597 */
598 static char *
599 kernenv_next(char *cp)
600 {
601
602 if (cp != NULL) {
603 while (*cp != 0)
604 cp++;
605 cp++;
606 if (*cp == 0)
607 cp = NULL;
608 }
609 return (cp);
610 }
611
612 void
613 tunable_int_init(void *data)
614 {
615 struct tunable_int *d = (struct tunable_int *)data;
616
617 TUNABLE_INT_FETCH(d->path, d->var);
618 }
619
620 void
621 tunable_long_init(void *data)
622 {
623 struct tunable_long *d = (struct tunable_long *)data;
624
625 TUNABLE_LONG_FETCH(d->path, d->var);
626 }
627
628 void
629 tunable_ulong_init(void *data)
630 {
631 struct tunable_ulong *d = (struct tunable_ulong *)data;
632
633 TUNABLE_ULONG_FETCH(d->path, d->var);
634 }
635
636 void
637 tunable_quad_init(void *data)
638 {
639 struct tunable_quad *d = (struct tunable_quad *)data;
640
641 TUNABLE_QUAD_FETCH(d->path, d->var);
642 }
643
644 void
645 tunable_str_init(void *data)
646 {
647 struct tunable_str *d = (struct tunable_str *)data;
648
649 TUNABLE_STR_FETCH(d->path, d->var, d->size);
650 }
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