kern_environment.c revision 239257
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 239257 2012-08-14 19:16:30Z 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 80sys_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 } 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 size_t len; 229 int i; 230 231 kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV, 232 M_WAITOK | M_ZERO); 233 i = 0; 234 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) { 235 len = strlen(cp) + 1; 236 if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) { 237 printf("WARNING: too long kenv string, ignoring %s\n", 238 cp); 239 continue; 240 } 241 if (i < KENV_SIZE) { 242 kenvp[i] = malloc(len, M_KENV, M_WAITOK); 243 strcpy(kenvp[i++], cp); 244 } else 245 printf( 246 "WARNING: too many kenv strings, ignoring %s\n", 247 cp); 248 } 249 kenvp[i] = NULL; 250 251 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF); 252 dynamic_kenv = 1; 253} 254SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL); 255 256void 257freeenv(char *env) 258{ 259 260 if (dynamic_kenv) 261 free(env, M_KENV); 262} 263 264/* 265 * Internal functions for string lookup. 266 */ 267static char * 268_getenv_dynamic(const char *name, int *idx) 269{ 270 char *cp; 271 int len, i; 272 273 mtx_assert(&kenv_lock, MA_OWNED); 274 len = strlen(name); 275 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) { 276 if ((strncmp(cp, name, len) == 0) && 277 (cp[len] == '=')) { 278 if (idx != NULL) 279 *idx = i; 280 return (cp + len + 1); 281 } 282 } 283 return (NULL); 284} 285 286static char * 287_getenv_static(const char *name) 288{ 289 char *cp, *ep; 290 int len; 291 292 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) { 293 for (ep = cp; (*ep != '=') && (*ep != 0); ep++) 294 ; 295 if (*ep != '=') 296 continue; 297 len = ep - cp; 298 ep++; 299 if (!strncmp(name, cp, len) && name[len] == 0) 300 return (ep); 301 } 302 return (NULL); 303} 304 305/* 306 * Look up an environment variable by name. 307 * Return a pointer to the string if found. 308 * The pointer has to be freed with freeenv() 309 * after use. 310 */ 311char * 312getenv(const char *name) 313{ 314 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1]; 315 char *ret, *cp; 316 int len; 317 318 if (dynamic_kenv) { 319 mtx_lock(&kenv_lock); 320 cp = _getenv_dynamic(name, NULL); 321 if (cp != NULL) { 322 strcpy(buf, cp); 323 mtx_unlock(&kenv_lock); 324 len = strlen(buf) + 1; 325 ret = malloc(len, M_KENV, M_WAITOK); 326 strcpy(ret, buf); 327 } else { 328 mtx_unlock(&kenv_lock); 329 ret = NULL; 330 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 331 "getenv"); 332 } 333 } else 334 ret = _getenv_static(name); 335 return (ret); 336} 337 338/* 339 * Test if an environment variable is defined. 340 */ 341int 342testenv(const char *name) 343{ 344 char *cp; 345 346 if (dynamic_kenv) { 347 mtx_lock(&kenv_lock); 348 cp = _getenv_dynamic(name, NULL); 349 mtx_unlock(&kenv_lock); 350 } else 351 cp = _getenv_static(name); 352 if (cp != NULL) 353 return (1); 354 return (0); 355} 356 357static int 358setenv_static(const char *name, const char *value) 359{ 360 int len; 361 362 if (env_pos >= env_len) 363 return (-1); 364 365 /* Check space for x=y and two nuls */ 366 len = strlen(name) + strlen(value); 367 if (len + 3 < env_len - env_pos) { 368 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value); 369 env_pos += len+1; 370 kern_envp[env_pos] = '\0'; 371 return (0); 372 } else 373 return (-1); 374 375} 376 377/* 378 * Set an environment variable by name. 379 */ 380int 381setenv(const char *name, const char *value) 382{ 383 char *buf, *cp, *oldenv; 384 int namelen, vallen, i; 385 386 if (dynamic_kenv == 0 && env_len > 0) 387 return (setenv_static(name, value)); 388 389 KENV_CHECK; 390 391 namelen = strlen(name) + 1; 392 if (namelen > KENV_MNAMELEN + 1) 393 return (-1); 394 vallen = strlen(value) + 1; 395 if (vallen > KENV_MVALLEN + 1) 396 return (-1); 397 buf = malloc(namelen + vallen, M_KENV, M_WAITOK); 398 sprintf(buf, "%s=%s", name, value); 399 400 mtx_lock(&kenv_lock); 401 cp = _getenv_dynamic(name, &i); 402 if (cp != NULL) { 403 oldenv = kenvp[i]; 404 kenvp[i] = buf; 405 mtx_unlock(&kenv_lock); 406 free(oldenv, M_KENV); 407 } else { 408 /* We add the option if it wasn't found */ 409 for (i = 0; (cp = kenvp[i]) != NULL; i++) 410 ; 411 412 /* Bounds checking */ 413 if (i < 0 || i >= KENV_SIZE) { 414 free(buf, M_KENV); 415 mtx_unlock(&kenv_lock); 416 return (-1); 417 } 418 419 kenvp[i] = buf; 420 kenvp[i + 1] = NULL; 421 mtx_unlock(&kenv_lock); 422 } 423 return (0); 424} 425 426/* 427 * Unset an environment variable string. 428 */ 429int 430unsetenv(const char *name) 431{ 432 char *cp, *oldenv; 433 int i, j; 434 435 KENV_CHECK; 436 437 mtx_lock(&kenv_lock); 438 cp = _getenv_dynamic(name, &i); 439 if (cp != NULL) { 440 oldenv = kenvp[i]; 441 for (j = i + 1; kenvp[j] != NULL; j++) 442 kenvp[i++] = kenvp[j]; 443 kenvp[i] = NULL; 444 mtx_unlock(&kenv_lock); 445 free(oldenv, M_KENV); 446 return (0); 447 } 448 mtx_unlock(&kenv_lock); 449 return (-1); 450} 451 452/* 453 * Return a string value from an environment variable. 454 */ 455int 456getenv_string(const char *name, char *data, int size) 457{ 458 char *tmp; 459 460 tmp = getenv(name); 461 if (tmp != NULL) { 462 strlcpy(data, tmp, size); 463 freeenv(tmp); 464 return (1); 465 } else 466 return (0); 467} 468 469/* 470 * Return an integer value from an environment variable. 471 */ 472int 473getenv_int(const char *name, int *data) 474{ 475 quad_t tmp; 476 int rval; 477 478 rval = getenv_quad(name, &tmp); 479 if (rval) 480 *data = (int) tmp; 481 return (rval); 482} 483 484/* 485 * Return an unsigned integer value from an environment variable. 486 */ 487int 488getenv_uint(const char *name, unsigned int *data) 489{ 490 quad_t tmp; 491 int rval; 492 493 rval = getenv_quad(name, &tmp); 494 if (rval) 495 *data = (unsigned int) tmp; 496 return (rval); 497} 498 499/* 500 * Return a long value from an environment variable. 501 */ 502int 503getenv_long(const char *name, long *data) 504{ 505 quad_t tmp; 506 int rval; 507 508 rval = getenv_quad(name, &tmp); 509 if (rval) 510 *data = (long) tmp; 511 return (rval); 512} 513 514/* 515 * Return an unsigned long value from an environment variable. 516 */ 517int 518getenv_ulong(const char *name, unsigned long *data) 519{ 520 quad_t tmp; 521 int rval; 522 523 rval = getenv_quad(name, &tmp); 524 if (rval) 525 *data = (unsigned long) tmp; 526 return (rval); 527} 528 529/* 530 * Return a quad_t value from an environment variable. 531 */ 532int 533getenv_quad(const char *name, quad_t *data) 534{ 535 char *value; 536 char *vtp; 537 quad_t iv; 538 539 value = getenv(name); 540 if (value == NULL) 541 return (0); 542 iv = strtoq(value, &vtp, 0); 543 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) { 544 freeenv(value); 545 return (0); 546 } 547 switch (vtp[0]) { 548 case 't': case 'T': 549 iv *= 1024; 550 case 'g': case 'G': 551 iv *= 1024; 552 case 'm': case 'M': 553 iv *= 1024; 554 case 'k': case 'K': 555 iv *= 1024; 556 case '\0': 557 break; 558 default: 559 freeenv(value); 560 return (0); 561 } 562 *data = iv; 563 freeenv(value); 564 return (1); 565} 566 567/* 568 * Find the next entry after the one which (cp) falls within, return a 569 * pointer to its start or NULL if there are no more. 570 */ 571static char * 572kernenv_next(char *cp) 573{ 574 575 if (cp != NULL) { 576 while (*cp != 0) 577 cp++; 578 cp++; 579 if (*cp == 0) 580 cp = NULL; 581 } 582 return (cp); 583} 584 585void 586tunable_int_init(void *data) 587{ 588 struct tunable_int *d = (struct tunable_int *)data; 589 590 TUNABLE_INT_FETCH(d->path, d->var); 591} 592 593void 594tunable_long_init(void *data) 595{ 596 struct tunable_long *d = (struct tunable_long *)data; 597 598 TUNABLE_LONG_FETCH(d->path, d->var); 599} 600 601void 602tunable_ulong_init(void *data) 603{ 604 struct tunable_ulong *d = (struct tunable_ulong *)data; 605 606 TUNABLE_ULONG_FETCH(d->path, d->var); 607} 608 609void 610tunable_quad_init(void *data) 611{ 612 struct tunable_quad *d = (struct tunable_quad *)data; 613 614 TUNABLE_QUAD_FETCH(d->path, d->var); 615} 616 617void 618tunable_str_init(void *data) 619{ 620 struct tunable_str *d = (struct tunable_str *)data; 621 622 TUNABLE_STR_FETCH(d->path, d->var, d->size); 623} 624