kern_environment.c revision 221607
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: head/sys/kern/kern_environment.c 221607 2011-05-07 17:59:07Z jh $"); 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 57static 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 */ 62char *kern_envp; 63static int env_len; 64static int env_pos; 65static char *kernenv_next(char *); 66 67/* dynamic environment variables */ 68char **kenvp; 69struct mtx kenv_lock; 70 71/* 72 * No need to protect this with a mutex since SYSINITS are single threaded. 73 */ 74int dynamic_kenv = 0; 75 76#define KENV_CHECK if (!dynamic_kenv) \ 77 panic("%s: called before SI_SUB_KMEM", __func__) 78 79int 80kenv(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, M_TEMP, M_WAITOK); 147 148 error = copyinstr(uap->name, name, KENV_MNAMELEN, 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) 180 len = KENV_MVALLEN; 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 } 208done: 209 free(name, M_TEMP); 210 return (error); 211} 212 213void 214init_static_kenv(char *buf, size_t len) 215{ 216 kern_envp = buf; 217 env_len = len; 218 env_pos = 0; 219} 220 221/* 222 * Setup the dynamic kernel environment. 223 */ 224static void 225init_dynamic_kenv(void *data __unused) 226{ 227 char *cp; 228 int len, i; 229 230 kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV, 231 M_WAITOK | M_ZERO); 232 i = 0; 233 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) { 234 len = strlen(cp) + 1; 235 if (i < KENV_SIZE) { 236 kenvp[i] = malloc(len, M_KENV, M_WAITOK); 237 strcpy(kenvp[i++], cp); 238 } else 239 printf( 240 "WARNING: too many kenv strings, ignoring %s\n", 241 cp); 242 } 243 kenvp[i] = NULL; 244 245 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF); 246 dynamic_kenv = 1; 247} 248SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL); 249 250void 251freeenv(char *env) 252{ 253 254 if (dynamic_kenv) 255 free(env, M_KENV); 256} 257 258/* 259 * Internal functions for string lookup. 260 */ 261static char * 262_getenv_dynamic(const char *name, int *idx) 263{ 264 char *cp; 265 int len, i; 266 267 mtx_assert(&kenv_lock, MA_OWNED); 268 len = strlen(name); 269 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) { 270 if ((strncmp(cp, name, len) == 0) && 271 (cp[len] == '=')) { 272 if (idx != NULL) 273 *idx = i; 274 return (cp + len + 1); 275 } 276 } 277 return (NULL); 278} 279 280static char * 281_getenv_static(const char *name) 282{ 283 char *cp, *ep; 284 int len; 285 286 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) { 287 for (ep = cp; (*ep != '=') && (*ep != 0); ep++) 288 ; 289 if (*ep != '=') 290 continue; 291 len = ep - cp; 292 ep++; 293 if (!strncmp(name, cp, len) && name[len] == 0) 294 return (ep); 295 } 296 return (NULL); 297} 298 299/* 300 * Look up an environment variable by name. 301 * Return a pointer to the string if found. 302 * The pointer has to be freed with freeenv() 303 * after use. 304 */ 305char * 306getenv(const char *name) 307{ 308 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1]; 309 char *ret, *cp; 310 int len; 311 312 if (dynamic_kenv) { 313 mtx_lock(&kenv_lock); 314 cp = _getenv_dynamic(name, NULL); 315 if (cp != NULL) { 316 strcpy(buf, cp); 317 mtx_unlock(&kenv_lock); 318 len = strlen(buf) + 1; 319 ret = malloc(len, M_KENV, M_WAITOK); 320 strcpy(ret, buf); 321 } else { 322 mtx_unlock(&kenv_lock); 323 ret = NULL; 324 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 325 "getenv"); 326 } 327 } else 328 ret = _getenv_static(name); 329 return (ret); 330} 331 332/* 333 * Test if an environment variable is defined. 334 */ 335int 336testenv(const char *name) 337{ 338 char *cp; 339 340 if (dynamic_kenv) { 341 mtx_lock(&kenv_lock); 342 cp = _getenv_dynamic(name, NULL); 343 mtx_unlock(&kenv_lock); 344 } else 345 cp = _getenv_static(name); 346 if (cp != NULL) 347 return (1); 348 return (0); 349} 350 351static int 352setenv_static(const char *name, const char *value) 353{ 354 int len; 355 356 if (env_pos >= env_len) 357 return (-1); 358 359 /* Check space for x=y and two nuls */ 360 len = strlen(name) + strlen(value); 361 if (len + 3 < env_len - env_pos) { 362 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value); 363 env_pos += len+1; 364 kern_envp[env_pos] = '\0'; 365 return (0); 366 } else 367 return (-1); 368 369} 370 371/* 372 * Set an environment variable by name. 373 */ 374int 375setenv(const char *name, const char *value) 376{ 377 char *buf, *cp, *oldenv; 378 int namelen, vallen, i; 379 380 if (dynamic_kenv == 0 && env_len > 0) 381 return (setenv_static(name, value)); 382 383 KENV_CHECK; 384 385 namelen = strlen(name) + 1; 386 if (namelen > KENV_MNAMELEN) 387 return (-1); 388 vallen = strlen(value) + 1; 389 if (vallen > KENV_MVALLEN) 390 return (-1); 391 buf = malloc(namelen + vallen, M_KENV, M_WAITOK); 392 sprintf(buf, "%s=%s", name, value); 393 394 mtx_lock(&kenv_lock); 395 cp = _getenv_dynamic(name, &i); 396 if (cp != NULL) { 397 oldenv = kenvp[i]; 398 kenvp[i] = buf; 399 mtx_unlock(&kenv_lock); 400 free(oldenv, M_KENV); 401 } else { 402 /* We add the option if it wasn't found */ 403 for (i = 0; (cp = kenvp[i]) != NULL; i++) 404 ; 405 406 /* Bounds checking */ 407 if (i < 0 || i >= KENV_SIZE) { 408 free(buf, M_KENV); 409 mtx_unlock(&kenv_lock); 410 return (-1); 411 } 412 413 kenvp[i] = buf; 414 kenvp[i + 1] = NULL; 415 mtx_unlock(&kenv_lock); 416 } 417 return (0); 418} 419 420/* 421 * Unset an environment variable string. 422 */ 423int 424unsetenv(const char *name) 425{ 426 char *cp, *oldenv; 427 int i, j; 428 429 KENV_CHECK; 430 431 mtx_lock(&kenv_lock); 432 cp = _getenv_dynamic(name, &i); 433 if (cp != NULL) { 434 oldenv = kenvp[i]; 435 for (j = i + 1; kenvp[j] != NULL; j++) 436 kenvp[i++] = kenvp[j]; 437 kenvp[i] = NULL; 438 mtx_unlock(&kenv_lock); 439 free(oldenv, M_KENV); 440 return (0); 441 } 442 mtx_unlock(&kenv_lock); 443 return (-1); 444} 445 446/* 447 * Return a string value from an environment variable. 448 */ 449int 450getenv_string(const char *name, char *data, int size) 451{ 452 char *tmp; 453 454 tmp = getenv(name); 455 if (tmp != NULL) { 456 strlcpy(data, tmp, size); 457 freeenv(tmp); 458 return (1); 459 } else 460 return (0); 461} 462 463/* 464 * Return an integer value from an environment variable. 465 */ 466int 467getenv_int(const char *name, int *data) 468{ 469 quad_t tmp; 470 int rval; 471 472 rval = getenv_quad(name, &tmp); 473 if (rval) 474 *data = (int) tmp; 475 return (rval); 476} 477 478/* 479 * Return an unsigned integer value from an environment variable. 480 */ 481int 482getenv_uint(const char *name, unsigned int *data) 483{ 484 quad_t tmp; 485 int rval; 486 487 rval = getenv_quad(name, &tmp); 488 if (rval) 489 *data = (unsigned int) tmp; 490 return (rval); 491} 492 493/* 494 * Return a long value from an environment variable. 495 */ 496int 497getenv_long(const char *name, long *data) 498{ 499 quad_t tmp; 500 int rval; 501 502 rval = getenv_quad(name, &tmp); 503 if (rval) 504 *data = (long) tmp; 505 return (rval); 506} 507 508/* 509 * Return an unsigned long value from an environment variable. 510 */ 511int 512getenv_ulong(const char *name, unsigned long *data) 513{ 514 quad_t tmp; 515 int rval; 516 517 rval = getenv_quad(name, &tmp); 518 if (rval) 519 *data = (unsigned long) tmp; 520 return (rval); 521} 522 523/* 524 * Return a quad_t value from an environment variable. 525 */ 526int 527getenv_quad(const char *name, quad_t *data) 528{ 529 char *value; 530 char *vtp; 531 quad_t iv; 532 533 value = getenv(name); 534 if (value == NULL) 535 return (0); 536 iv = strtoq(value, &vtp, 0); 537 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) { 538 freeenv(value); 539 return (0); 540 } 541 switch (vtp[0]) { 542 case 't': case 'T': 543 iv *= 1024; 544 case 'g': case 'G': 545 iv *= 1024; 546 case 'm': case 'M': 547 iv *= 1024; 548 case 'k': case 'K': 549 iv *= 1024; 550 case '\0': 551 break; 552 default: 553 freeenv(value); 554 return (0); 555 } 556 *data = iv; 557 freeenv(value); 558 return (1); 559} 560 561/* 562 * Find the next entry after the one which (cp) falls within, return a 563 * pointer to its start or NULL if there are no more. 564 */ 565static char * 566kernenv_next(char *cp) 567{ 568 569 if (cp != NULL) { 570 while (*cp != 0) 571 cp++; 572 cp++; 573 if (*cp == 0) 574 cp = NULL; 575 } 576 return (cp); 577} 578 579void 580tunable_int_init(void *data) 581{ 582 struct tunable_int *d = (struct tunable_int *)data; 583 584 TUNABLE_INT_FETCH(d->path, d->var); 585} 586 587void 588tunable_long_init(void *data) 589{ 590 struct tunable_long *d = (struct tunable_long *)data; 591 592 TUNABLE_LONG_FETCH(d->path, d->var); 593} 594 595void 596tunable_ulong_init(void *data) 597{ 598 struct tunable_ulong *d = (struct tunable_ulong *)data; 599 600 TUNABLE_ULONG_FETCH(d->path, d->var); 601} 602 603void 604tunable_quad_init(void *data) 605{ 606 struct tunable_quad *d = (struct tunable_quad *)data; 607 608 TUNABLE_QUAD_FETCH(d->path, d->var); 609} 610 611void 612tunable_str_init(void *data) 613{ 614 struct tunable_str *d = (struct tunable_str *)data; 615 616 TUNABLE_STR_FETCH(d->path, d->var, d->size); 617} 618