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 * $FreeBSD: head/sys/kern/kern_environment.c 106308 2002-11-01 20:46:53Z rwatson $
27 */
28
29/*
30 * The unified bootloader passes us a pointer to a preserved copy of
31 * bootstrap/kernel environment variables. We convert them to a
32 * dynamic array of strings later when the VM subsystem is up.
33 *
34 * We make these available through the kenv(2) syscall for userland
35 * and through getenv()/freeenv() setenv() unsetenv() testenv() for
36 * the kernel.
37 */
38
39#include "opt_mac.h"
40
41#include <sys/types.h>
42#include <sys/param.h>
43#include <sys/proc.h>
44#include <sys/queue.h>
45#include <sys/lock.h>
46#include <sys/mac.h>
47#include <sys/malloc.h>
48#include <sys/mutex.h>
49#include <sys/kernel.h>
50#include <sys/sx.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
57MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
58
59#define KENV_SIZE 512 /* Maximum number of environment strings */
60
61/* pointer to the static environment */
62char *kern_envp;
63static char *kernenv_next(char *);
64
65/* dynamic environment variables */
66char **kenvp;
67struct sx kenv_lock;
68
69/*
70 * No need to protect this with a mutex
71 * since SYSINITS are single threaded.
72 */
73int dynamic_kenv = 0;
74
75#define KENV_CHECK if (!dynamic_kenv) \
76 panic("%s: called before SI_SUB_KMEM", __func__)
77
78int
79kenv(td, uap)
80 struct thread *td;
81 struct kenv_args /* {
82 syscallarg(int) what;
83 syscallarg(const char *) name;
84 syscallarg(char *) value;
85 syscallarg(int) len;
86 } */ *uap;
87{
88 char *name, *value;
89 size_t len, done;
90 int error, i;
91
92 KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = 0"));
93
94 error = 0;
95 if (SCARG(uap, what) == KENV_DUMP) {
96#ifdef MAC
97 error = mac_check_kenv_dump(td->td_ucred);
98 if (error)
99 return (error);
100#endif
101 len = 0;
102 /* Return the size if called with a NULL buffer */
103 if (SCARG(uap, value) == NULL) {
104 sx_slock(&kenv_lock);
105 for (i = 0; kenvp[i] != NULL; i++)
106 len += strlen(kenvp[i]) + 1;
107 sx_sunlock(&kenv_lock);
108 td->td_retval[0] = len;
109 return (0);
110 }
111 done = 0;
112 sx_slock(&kenv_lock);
113 for (i = 0; kenvp[i] != NULL && done < SCARG(uap, len); i++) {
114 len = min(strlen(kenvp[i]) + 1, SCARG(uap, len) - done);
115 error = copyout(kenvp[i], SCARG(uap, value) + done,
116 len);
117 if (error) {
118 sx_sunlock(&kenv_lock);
119 return (error);
120 }
121 done += len;
122 }
123 sx_sunlock(&kenv_lock);
124 return (0);
125 }
126
127 if ((SCARG(uap, what) == KENV_SET) ||
128 (SCARG(uap, what) == KENV_UNSET)) {
129 error = suser(td);
130 if (error)
131 return (error);
132 }
133
134 name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
135
136 error = copyinstr(SCARG(uap, name), name, KENV_MNAMELEN, NULL);
137 if (error)
138 goto done;
139
140 switch (SCARG(uap, what)) {
141 case KENV_GET:
142#ifdef MAC
143 error = mac_check_kenv_get(td->td_ucred, name);
144 if (error)
145 goto done;
146#endif
147 value = getenv(name);
148 if (value == NULL) {
149 error = ENOENT;
150 goto done;
151 }
152 len = strlen(value) + 1;
153 if (len > SCARG(uap, len))
154 len = SCARG(uap, len);
155 error = copyout(value, SCARG(uap, value), len);
156 freeenv(value);
157 if (error)
158 goto done;
159 td->td_retval[0] = len;
160 break;
161 case KENV_SET:
162 len = SCARG(uap, len);
163 if (len < 1) {
164 error = EINVAL;
165 goto done;
166 }
167 if (len > KENV_MVALLEN)
168 len = KENV_MVALLEN;
169 value = malloc(len, M_TEMP, M_WAITOK);
170 error = copyinstr(SCARG(uap, value), value, len, NULL);
171 if (error) {
172 free(value, M_TEMP);
173 goto done;
174 }
175#ifdef MAC
176 error = mac_check_kenv_set(td->td_ucred, name, value);
177 if (error == 0)
178#endif
179 setenv(name, value);
180 free(value, M_TEMP);
181 break;
182 case KENV_UNSET:
183#ifdef MAC
184 error = mac_check_kenv_unset(td->td_ucred, name);
185 if (error)
186 goto done;
187#endif
188 error = unsetenv(name);
189 if (error)
190 error = ENOENT;
191 break;
192 default:
193 error = EINVAL;
194 break;
195 }
196done:
197 free(name, M_TEMP);
198 return (error);
199}
200
201/*
202 * Setup the dynamic kernel environment.
203 */
204static void
205init_dynamic_kenv(void *data __unused)
206{
207 char *cp;
208 int len, i;
209
210 kenvp = malloc(KENV_SIZE * sizeof(char *), M_KENV, M_WAITOK | M_ZERO);
211 i = 0;
212 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
213 len = strlen(cp) + 1;
214 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
215 strcpy(kenvp[i++], cp);
216 }
217 kenvp[i] = NULL;
218
219 sx_init(&kenv_lock, "kernel environment");
220 dynamic_kenv = 1;
221}
222SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
223
224void
225freeenv(char *env)
226{
227
228 if (dynamic_kenv)
229 free(env, M_KENV);
230}
231
232/*
233 * Internal functions for string lookup.
234 */
235static char *
236_getenv_dynamic(const char *name, int *idx)
237{
238 char *cp;
239 int len, i;
240
241 sx_assert(&kenv_lock, SX_LOCKED);
242 len = strlen(name);
243 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
244 if ((cp[len] == '=') &&
245 (strncmp(cp, name, len) == 0)) {
246 if (idx != NULL)
247 *idx = i;
248 return (cp + len + 1);
249 }
250 }
251 return (NULL);
252}
253
254static char *
255_getenv_static(const char *name)
256{
257 char *cp, *ep;
258 int len;
259
260 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
261 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
262 ;
263 if (*ep != '=')
264 continue;
265 len = ep - cp;
266 ep++;
267 if (!strncmp(name, cp, len) && name[len] == 0)
268 return (ep);
269 }
270 return (NULL);
271}
272
273/*
274 * Look up an environment variable by name.
275 * Return a pointer to the string if found.
276 * The pointer has to be freed with freeenv()
277 * after use.
278 */
279char *
280getenv(const char *name)
281{
282 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
283 char *ret, *cp;
284 int len;
285
286 if (dynamic_kenv) {
287 sx_slock(&kenv_lock);
288 cp = _getenv_dynamic(name, NULL);
289 if (cp != NULL) {
290 strcpy(buf, cp);
291 sx_sunlock(&kenv_lock);
292 len = strlen(buf) + 1;
293 ret = malloc(len, M_KENV, M_WAITOK);
294 strcpy(ret, buf);
295 } else {
296 sx_sunlock(&kenv_lock);
297 ret = NULL;
298 }
299 } else
300 ret = _getenv_static(name);
301 return (ret);
302}
303
304/*
305 * Test if an environment variable is defined.
306 */
307int
308testenv(const char *name)
309{
310 char *cp;
311
312 if (dynamic_kenv) {
313 sx_slock(&kenv_lock);
314 cp = _getenv_dynamic(name, NULL);
315 sx_sunlock(&kenv_lock);
316 } else
317 cp = _getenv_static(name);
318 if (cp != NULL)
319 return (1);
320 return (0);
321}
322
323/*
324 * Set an environment variable by name.
325 */
326int
327setenv(const char *name, const char *value)
328{
329 char *buf, *cp, *oldenv;
330 int namelen, vallen, i;
331
332 KENV_CHECK;
333
334 namelen = strlen(name) + 1;
335 if (namelen > KENV_MNAMELEN)
336 return (-1);
337 vallen = strlen(value) + 1;
338 if (vallen > KENV_MVALLEN)
339 return (-1);
340 buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
341 sprintf(buf, "%s=%s", name, value);
342
343 sx_xlock(&kenv_lock);
344 cp = _getenv_dynamic(name, &i);
345 if (cp != NULL) {
346 oldenv = kenvp[i];
347 kenvp[i] = buf;
348 sx_xunlock(&kenv_lock);
349 free(oldenv, M_KENV);
350 } else {
351 /* We add the option if it wasn't found */
352 for (i = 0; (cp = kenvp[i]) != NULL; i++)
353 ;
354 kenvp[i] = buf;
355 kenvp[i + 1] = NULL;
356 sx_xunlock(&kenv_lock);
357 }
358 return (0);
359}
360
361/*
362 * Unset an environment variable string.
363 */
364int
365unsetenv(const char *name)
366{
367 char *cp, *oldenv;
368 int i, j;
369
370 KENV_CHECK;
371
372 sx_xlock(&kenv_lock);
373 cp = _getenv_dynamic(name, &i);
374 if (cp != NULL) {
375 oldenv = kenvp[i];
376 for (j = i + 1; kenvp[j] != NULL; j++)
377 kenvp[i++] = kenvp[j];
378 kenvp[i] = NULL;
379 sx_xunlock(&kenv_lock);
380 free(oldenv, M_KENV);
381 return (0);
382 }
383 sx_xunlock(&kenv_lock);
384 return (-1);
385}
386
387/*
388 * Return a string value from an environment variable.
389 */
390int
391getenv_string(const char *name, char *data, int size)
392{
393 char *tmp;
394
395 tmp = getenv(name);
396 if (tmp != NULL) {
397 strlcpy(data, tmp, size);
398 freeenv(tmp);
399 return (1);
400 } else
401 return (0);
402}
403
404/*
405 * Return an integer value from an environment variable.
406 */
407int
408getenv_int(const char *name, int *data)
409{
410 quad_t tmp;
411 int rval;
412
413 rval = getenv_quad(name, &tmp);
414 if (rval)
415 *data = (int) tmp;
416 return (rval);
417}
418
419/*
420 * Return a quad_t value from an environment variable.
421 */
422int
423getenv_quad(const char *name, quad_t *data)
424{
425 char *value;
426 char *vtp;
427 quad_t iv;
428
429 value = getenv(name);
430 if (value == NULL)
431 return (0);
432 iv = strtoq(value, &vtp, 0);
433 if ((vtp == value) || (*vtp != '\0')) {
434 freeenv(value);
435 return (0);
436 }
437 freeenv(value);
438 *data = iv;
439 return (1);
440}
441
442/*
443 * Find the next entry after the one which (cp) falls within, return a
444 * pointer to its start or NULL if there are no more.
445 */
446static char *
447kernenv_next(char *cp)
448{
449
450 if (cp != NULL) {
451 while (*cp != 0)
452 cp++;
453 cp++;
454 if (*cp == 0)
455 cp = NULL;
456 }
457 return (cp);
458}
459
460void
461tunable_int_init(void *data)
462{
463 struct tunable_int *d = (struct tunable_int *)data;
464
465 TUNABLE_INT_FETCH(d->path, d->var);
466}
467
468void
469tunable_quad_init(void *data)
470{
471 struct tunable_quad *d = (struct tunable_quad *)data;
472
473 TUNABLE_QUAD_FETCH(d->path, d->var);
474}
475
476void
477tunable_str_init(void *data)
478{
479 struct tunable_str *d = (struct tunable_str *)data;
480
481 TUNABLE_STR_FETCH(d->path, d->var, d->size);
482}