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("$FreeBSD$");
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
sys_kenv(td,uap)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 * 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
init_static_kenv(char * buf,size_t len)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
init_dynamic_kenv(void * data __unused)257 init_dynamic_kenv(void *data __unused)
258 {
259 char *cp, *cpnext;
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 = cpnext) {
268 cpnext = kernenv_next(cp);
269 len = strlen(cp) + 1;
270 if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
271 printf(
272 "WARNING: too long kenv string, ignoring %s\n",
273 cp);
274 continue;
275 }
276 if (i < KENV_SIZE) {
277 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
278 strcpy(kenvp[i++], cp);
279 memset(cp, 0, strlen(cp));
280 } else
281 printf(
282 "WARNING: too many kenv strings, ignoring %s\n",
283 cp);
284 }
285 }
286 kenvp[i] = NULL;
287
288 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
289 dynamic_kenv = 1;
290 }
291 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
292
293 void
freeenv(char * env)294 freeenv(char *env)
295 {
296
297 if (dynamic_kenv && env != NULL) {
298 memset(env, 0, strlen(env));
299 free(env, M_KENV);
300 }
301 }
302
303 /*
304 * Internal functions for string lookup.
305 */
306 static char *
_getenv_dynamic(const char * name,int * idx)307 _getenv_dynamic(const char *name, int *idx)
308 {
309 char *cp;
310 int len, i;
311
312 mtx_assert(&kenv_lock, MA_OWNED);
313 len = strlen(name);
314 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
315 if ((strncmp(cp, name, len) == 0) &&
316 (cp[len] == '=')) {
317 if (idx != NULL)
318 *idx = i;
319 return (cp + len + 1);
320 }
321 }
322 return (NULL);
323 }
324
325 static char *
_getenv_static(const char * name)326 _getenv_static(const char *name)
327 {
328 char *cp, *ep;
329 int len;
330
331 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
332 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
333 ;
334 if (*ep != '=')
335 continue;
336 len = ep - cp;
337 ep++;
338 if (!strncmp(name, cp, len) && name[len] == 0)
339 return (ep);
340 }
341 return (NULL);
342 }
343
344 /*
345 * Look up an environment variable by name.
346 * Return a pointer to the string if found.
347 * The pointer has to be freed with freeenv()
348 * after use.
349 */
350 char *
kern_getenv(const char * name)351 kern_getenv(const char *name)
352 {
353 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
354 char *ret;
355
356 if (dynamic_kenv) {
357 if (getenv_string(name, buf, sizeof(buf))) {
358 ret = strdup(buf, M_KENV);
359 } else {
360 ret = NULL;
361 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
362 "getenv");
363 }
364 } else
365 ret = _getenv_static(name);
366 return (ret);
367 }
368
369 /*
370 * Test if an environment variable is defined.
371 */
372 int
testenv(const char * name)373 testenv(const char *name)
374 {
375 char *cp;
376
377 if (dynamic_kenv) {
378 mtx_lock(&kenv_lock);
379 cp = _getenv_dynamic(name, NULL);
380 mtx_unlock(&kenv_lock);
381 } else
382 cp = _getenv_static(name);
383 if (cp != NULL)
384 return (1);
385 return (0);
386 }
387
388 static int
setenv_static(const char * name,const char * value)389 setenv_static(const char *name, const char *value)
390 {
391 int len;
392
393 if (env_pos >= env_len)
394 return (-1);
395
396 /* Check space for x=y and two nuls */
397 len = strlen(name) + strlen(value);
398 if (len + 3 < env_len - env_pos) {
399 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
400 env_pos += len+1;
401 kern_envp[env_pos] = '\0';
402 return (0);
403 } else
404 return (-1);
405
406 }
407
408 /*
409 * Set an environment variable by name.
410 */
411 int
kern_setenv(const char * name,const char * value)412 kern_setenv(const char *name, const char *value)
413 {
414 char *buf, *cp, *oldenv;
415 int namelen, vallen, i;
416
417 if (dynamic_kenv == 0 && env_len > 0)
418 return (setenv_static(name, value));
419
420 KENV_CHECK;
421
422 namelen = strlen(name) + 1;
423 if (namelen > KENV_MNAMELEN + 1)
424 return (-1);
425 vallen = strlen(value) + 1;
426 if (vallen > KENV_MVALLEN + 1)
427 return (-1);
428 buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
429 sprintf(buf, "%s=%s", name, value);
430
431 mtx_lock(&kenv_lock);
432 cp = _getenv_dynamic(name, &i);
433 if (cp != NULL) {
434 oldenv = kenvp[i];
435 kenvp[i] = buf;
436 mtx_unlock(&kenv_lock);
437 free(oldenv, M_KENV);
438 } else {
439 /* We add the option if it wasn't found */
440 for (i = 0; (cp = kenvp[i]) != NULL; i++)
441 ;
442
443 /* Bounds checking */
444 if (i < 0 || i >= KENV_SIZE) {
445 free(buf, M_KENV);
446 mtx_unlock(&kenv_lock);
447 return (-1);
448 }
449
450 kenvp[i] = buf;
451 kenvp[i + 1] = NULL;
452 mtx_unlock(&kenv_lock);
453 }
454 return (0);
455 }
456
457 /*
458 * Unset an environment variable string.
459 */
460 int
kern_unsetenv(const char * name)461 kern_unsetenv(const char *name)
462 {
463 char *cp, *oldenv;
464 int i, j;
465
466 KENV_CHECK;
467
468 mtx_lock(&kenv_lock);
469 cp = _getenv_dynamic(name, &i);
470 if (cp != NULL) {
471 oldenv = kenvp[i];
472 for (j = i + 1; kenvp[j] != NULL; j++)
473 kenvp[i++] = kenvp[j];
474 kenvp[i] = NULL;
475 mtx_unlock(&kenv_lock);
476 memset(oldenv, 0, strlen(oldenv));
477 free(oldenv, M_KENV);
478 return (0);
479 }
480 mtx_unlock(&kenv_lock);
481 return (-1);
482 }
483
484 /*
485 * Return a string value from an environment variable.
486 */
487 int
getenv_string(const char * name,char * data,int size)488 getenv_string(const char *name, char *data, int size)
489 {
490 char *cp;
491
492 if (dynamic_kenv) {
493 mtx_lock(&kenv_lock);
494 cp = _getenv_dynamic(name, NULL);
495 if (cp != NULL)
496 strlcpy(data, cp, size);
497 mtx_unlock(&kenv_lock);
498 } else {
499 cp = _getenv_static(name);
500 if (cp != NULL)
501 strlcpy(data, cp, size);
502 }
503 return (cp != NULL);
504 }
505
506 /*
507 * Return an integer value from an environment variable.
508 */
509 int
getenv_int(const char * name,int * data)510 getenv_int(const char *name, int *data)
511 {
512 quad_t tmp;
513 int rval;
514
515 rval = getenv_quad(name, &tmp);
516 if (rval)
517 *data = (int) tmp;
518 return (rval);
519 }
520
521 /*
522 * Return an unsigned integer value from an environment variable.
523 */
524 int
getenv_uint(const char * name,unsigned int * data)525 getenv_uint(const char *name, unsigned int *data)
526 {
527 quad_t tmp;
528 int rval;
529
530 rval = getenv_quad(name, &tmp);
531 if (rval)
532 *data = (unsigned int) tmp;
533 return (rval);
534 }
535
536 /*
537 * Return a long value from an environment variable.
538 */
539 int
getenv_long(const char * name,long * data)540 getenv_long(const char *name, long *data)
541 {
542 quad_t tmp;
543 int rval;
544
545 rval = getenv_quad(name, &tmp);
546 if (rval)
547 *data = (long) tmp;
548 return (rval);
549 }
550
551 /*
552 * Return an unsigned long value from an environment variable.
553 */
554 int
getenv_ulong(const char * name,unsigned long * data)555 getenv_ulong(const char *name, unsigned long *data)
556 {
557 quad_t tmp;
558 int rval;
559
560 rval = getenv_quad(name, &tmp);
561 if (rval)
562 *data = (unsigned long) tmp;
563 return (rval);
564 }
565
566 /*
567 * Return a quad_t value from an environment variable.
568 */
569 int
getenv_quad(const char * name,quad_t * data)570 getenv_quad(const char *name, quad_t *data)
571 {
572 char value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
573 char *vtp;
574 quad_t iv;
575
576 if (!getenv_string(name, value, sizeof(value)))
577 return (0);
578 iv = strtoq(value, &vtp, 0);
579 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
580 return (0);
581 switch (vtp[0]) {
582 case 't': case 'T':
583 iv *= 1024;
584 case 'g': case 'G':
585 iv *= 1024;
586 case 'm': case 'M':
587 iv *= 1024;
588 case 'k': case 'K':
589 iv *= 1024;
590 case '\0':
591 break;
592 default:
593 return (0);
594 }
595 *data = iv;
596 return (1);
597 }
598
599 /*
600 * Find the next entry after the one which (cp) falls within, return a
601 * pointer to its start or NULL if there are no more.
602 */
603 static char *
kernenv_next(char * cp)604 kernenv_next(char *cp)
605 {
606
607 if (cp != NULL) {
608 while (*cp != 0)
609 cp++;
610 cp++;
611 if (*cp == 0)
612 cp = NULL;
613 }
614 return (cp);
615 }
616
617 void
tunable_int_init(void * data)618 tunable_int_init(void *data)
619 {
620 struct tunable_int *d = (struct tunable_int *)data;
621
622 TUNABLE_INT_FETCH(d->path, d->var);
623 }
624
625 void
tunable_long_init(void * data)626 tunable_long_init(void *data)
627 {
628 struct tunable_long *d = (struct tunable_long *)data;
629
630 TUNABLE_LONG_FETCH(d->path, d->var);
631 }
632
633 void
tunable_ulong_init(void * data)634 tunable_ulong_init(void *data)
635 {
636 struct tunable_ulong *d = (struct tunable_ulong *)data;
637
638 TUNABLE_ULONG_FETCH(d->path, d->var);
639 }
640
641 void
tunable_quad_init(void * data)642 tunable_quad_init(void *data)
643 {
644 struct tunable_quad *d = (struct tunable_quad *)data;
645
646 TUNABLE_QUAD_FETCH(d->path, d->var);
647 }
648
649 void
tunable_str_init(void * data)650 tunable_str_init(void *data)
651 {
652 struct tunable_str *d = (struct tunable_str *)data;
653
654 TUNABLE_STR_FETCH(d->path, d->var, d->size);
655 }
656