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/5.3/sys/kern/kern_environment.c 136588 2004-10-16 08:43:07Z cvs2svn $");
39
40 #include "opt_mac.h"
41
42 #include <sys/types.h>
43 #include <sys/param.h>
44 #include <sys/proc.h>
45 #include <sys/queue.h>
46 #include <sys/lock.h>
47 #include <sys/mac.h>
48 #include <sys/malloc.h>
49 #include <sys/mutex.h>
50 #include <sys/kernel.h>
51 #include <sys/sx.h>
52 #include <sys/systm.h>
53 #include <sys/sysent.h>
54 #include <sys/sysproto.h>
55 #include <sys/libkern.h>
56 #include <sys/kenv.h>
57
58 MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
59
60 #define KENV_SIZE 512 /* Maximum number of environment strings */
61
62 /* pointer to the static environment */
63 char *kern_envp;
64 static char *kernenv_next(char *);
65
66 /* dynamic environment variables */
67 char **kenvp;
68 struct sx kenv_lock;
69
70 /*
71 * No need to protect this with a mutex
72 * 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 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;
90 size_t len, done, needed;
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_check_kenv_dump(td->td_ucred);
99 if (error)
100 return (error);
101 #endif
102 done = needed = 0;
103 sx_slock(&kenv_lock);
104 for (i = 0; kenvp[i] != NULL; i++) {
105 len = strlen(kenvp[i]) + 1;
106 needed += len;
107 len = min(len, uap->len - done);
108 /*
109 * If called with a NULL or insufficiently large
110 * buffer, just keep computing the required size.
111 */
112 if (uap->value != NULL && len > 0) {
113 error = copyout(kenvp[i], uap->value + done,
114 len);
115 if (error)
116 break;
117 done += len;
118 }
119 }
120 sx_sunlock(&kenv_lock);
121 td->td_retval[0] = ((done == needed) ? 0 : needed);
122 return (error);
123 }
124
125 if ((uap->what == KENV_SET) ||
126 (uap->what == KENV_UNSET)) {
127 error = suser(td);
128 if (error)
129 return (error);
130 }
131
132 name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
133
134 error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
135 if (error)
136 goto done;
137
138 switch (uap->what) {
139 case KENV_GET:
140 #ifdef MAC
141 error = mac_check_kenv_get(td->td_ucred, name);
142 if (error)
143 goto done;
144 #endif
145 value = getenv(name);
146 if (value == NULL) {
147 error = ENOENT;
148 goto done;
149 }
150 len = strlen(value) + 1;
151 if (len > uap->len)
152 len = uap->len;
153 error = copyout(value, uap->value, len);
154 freeenv(value);
155 if (error)
156 goto done;
157 td->td_retval[0] = len;
158 break;
159 case KENV_SET:
160 len = uap->len;
161 if (len < 1) {
162 error = EINVAL;
163 goto done;
164 }
165 if (len > KENV_MVALLEN)
166 len = KENV_MVALLEN;
167 value = malloc(len, M_TEMP, M_WAITOK);
168 error = copyinstr(uap->value, value, len, NULL);
169 if (error) {
170 free(value, M_TEMP);
171 goto done;
172 }
173 #ifdef MAC
174 error = mac_check_kenv_set(td->td_ucred, name, value);
175 if (error == 0)
176 #endif
177 setenv(name, value);
178 free(value, M_TEMP);
179 break;
180 case KENV_UNSET:
181 #ifdef MAC
182 error = mac_check_kenv_unset(td->td_ucred, name);
183 if (error)
184 goto done;
185 #endif
186 error = unsetenv(name);
187 if (error)
188 error = ENOENT;
189 break;
190 default:
191 error = EINVAL;
192 break;
193 }
194 done:
195 free(name, M_TEMP);
196 return (error);
197 }
198
199 /*
200 * Setup the dynamic kernel environment.
201 */
202 static void
203 init_dynamic_kenv(void *data __unused)
204 {
205 char *cp;
206 int len, i;
207
208 kenvp = malloc(KENV_SIZE * sizeof(char *), M_KENV, M_WAITOK | M_ZERO);
209 i = 0;
210 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
211 len = strlen(cp) + 1;
212 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
213 strcpy(kenvp[i++], cp);
214 }
215 kenvp[i] = NULL;
216
217 sx_init(&kenv_lock, "kernel environment");
218 dynamic_kenv = 1;
219 }
220 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
221
222 void
223 freeenv(char *env)
224 {
225
226 if (dynamic_kenv)
227 free(env, M_KENV);
228 }
229
230 /*
231 * Internal functions for string lookup.
232 */
233 static char *
234 _getenv_dynamic(const char *name, int *idx)
235 {
236 char *cp;
237 int len, i;
238
239 sx_assert(&kenv_lock, SX_LOCKED);
240 len = strlen(name);
241 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
242 if ((cp[len] == '=') &&
243 (strncmp(cp, name, len) == 0)) {
244 if (idx != NULL)
245 *idx = i;
246 return (cp + len + 1);
247 }
248 }
249 return (NULL);
250 }
251
252 static char *
253 _getenv_static(const char *name)
254 {
255 char *cp, *ep;
256 int len;
257
258 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
259 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
260 ;
261 if (*ep != '=')
262 continue;
263 len = ep - cp;
264 ep++;
265 if (!strncmp(name, cp, len) && name[len] == 0)
266 return (ep);
267 }
268 return (NULL);
269 }
270
271 /*
272 * Look up an environment variable by name.
273 * Return a pointer to the string if found.
274 * The pointer has to be freed with freeenv()
275 * after use.
276 */
277 char *
278 getenv(const char *name)
279 {
280 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
281 char *ret, *cp;
282 int len;
283
284 if (dynamic_kenv) {
285 sx_slock(&kenv_lock);
286 cp = _getenv_dynamic(name, NULL);
287 if (cp != NULL) {
288 strcpy(buf, cp);
289 sx_sunlock(&kenv_lock);
290 len = strlen(buf) + 1;
291 ret = malloc(len, M_KENV, M_WAITOK);
292 strcpy(ret, buf);
293 } else {
294 sx_sunlock(&kenv_lock);
295 ret = NULL;
296 }
297 } else
298 ret = _getenv_static(name);
299 return (ret);
300 }
301
302 /*
303 * Test if an environment variable is defined.
304 */
305 int
306 testenv(const char *name)
307 {
308 char *cp;
309
310 if (dynamic_kenv) {
311 sx_slock(&kenv_lock);
312 cp = _getenv_dynamic(name, NULL);
313 sx_sunlock(&kenv_lock);
314 } else
315 cp = _getenv_static(name);
316 if (cp != NULL)
317 return (1);
318 return (0);
319 }
320
321 /*
322 * Set an environment variable by name.
323 */
324 int
325 setenv(const char *name, const char *value)
326 {
327 char *buf, *cp, *oldenv;
328 int namelen, vallen, i;
329
330 KENV_CHECK;
331
332 namelen = strlen(name) + 1;
333 if (namelen > KENV_MNAMELEN)
334 return (-1);
335 vallen = strlen(value) + 1;
336 if (vallen > KENV_MVALLEN)
337 return (-1);
338 buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
339 sprintf(buf, "%s=%s", name, value);
340
341 sx_xlock(&kenv_lock);
342 cp = _getenv_dynamic(name, &i);
343 if (cp != NULL) {
344 oldenv = kenvp[i];
345 kenvp[i] = buf;
346 sx_xunlock(&kenv_lock);
347 free(oldenv, M_KENV);
348 } else {
349 /* We add the option if it wasn't found */
350 for (i = 0; (cp = kenvp[i]) != NULL; i++)
351 ;
352 kenvp[i] = buf;
353 kenvp[i + 1] = NULL;
354 sx_xunlock(&kenv_lock);
355 }
356 return (0);
357 }
358
359 /*
360 * Unset an environment variable string.
361 */
362 int
363 unsetenv(const char *name)
364 {
365 char *cp, *oldenv;
366 int i, j;
367
368 KENV_CHECK;
369
370 sx_xlock(&kenv_lock);
371 cp = _getenv_dynamic(name, &i);
372 if (cp != NULL) {
373 oldenv = kenvp[i];
374 for (j = i + 1; kenvp[j] != NULL; j++)
375 kenvp[i++] = kenvp[j];
376 kenvp[i] = NULL;
377 sx_xunlock(&kenv_lock);
378 free(oldenv, M_KENV);
379 return (0);
380 }
381 sx_xunlock(&kenv_lock);
382 return (-1);
383 }
384
385 /*
386 * Return a string value from an environment variable.
387 */
388 int
389 getenv_string(const char *name, char *data, int size)
390 {
391 char *tmp;
392
393 tmp = getenv(name);
394 if (tmp != NULL) {
395 strlcpy(data, tmp, size);
396 freeenv(tmp);
397 return (1);
398 } else
399 return (0);
400 }
401
402 /*
403 * Return an integer value from an environment variable.
404 */
405 int
406 getenv_int(const char *name, int *data)
407 {
408 quad_t tmp;
409 int rval;
410
411 rval = getenv_quad(name, &tmp);
412 if (rval)
413 *data = (int) tmp;
414 return (rval);
415 }
416
417 /*
418 * Return a quad_t value from an environment variable.
419 */
420 int
421 getenv_quad(const char *name, quad_t *data)
422 {
423 char *value;
424 char *vtp;
425 quad_t iv;
426
427 value = getenv(name);
428 if (value == NULL)
429 return (0);
430 iv = strtoq(value, &vtp, 0);
431 if ((vtp == value) || (*vtp != '\0')) {
432 freeenv(value);
433 return (0);
434 }
435 freeenv(value);
436 *data = iv;
437 return (1);
438 }
439
440 /*
441 * Find the next entry after the one which (cp) falls within, return a
442 * pointer to its start or NULL if there are no more.
443 */
444 static char *
445 kernenv_next(char *cp)
446 {
447
448 if (cp != NULL) {
449 while (*cp != 0)
450 cp++;
451 cp++;
452 if (*cp == 0)
453 cp = NULL;
454 }
455 return (cp);
456 }
457
458 void
459 tunable_int_init(void *data)
460 {
461 struct tunable_int *d = (struct tunable_int *)data;
462
463 TUNABLE_INT_FETCH(d->path, d->var);
464 }
465
466 void
467 tunable_quad_init(void *data)
468 {
469 struct tunable_quad *d = (struct tunable_quad *)data;
470
471 TUNABLE_QUAD_FETCH(d->path, d->var);
472 }
473
474 void
475 tunable_str_init(void *data)
476 {
477 struct tunable_str *d = (struct tunable_str *)data;
478
479 TUNABLE_STR_FETCH(d->path, d->var, d->size);
480 }
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