kern_environment.c revision 294683
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: stable/10/sys/kern/kern_environment.c 294683 2016-01-24 21:04:06Z ian $"); 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} 212 213/* 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 */ 238void 239init_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 */ 256static void 257init_dynamic_kenv(void *data __unused) 258{ 259 char *cp; 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 = kernenv_next(cp)) { 268 len = strlen(cp) + 1; 269 if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) { 270 printf( 271 "WARNING: too long kenv string, ignoring %s\n", 272 cp); 273 continue; 274 } 275 if (i < KENV_SIZE) { 276 kenvp[i] = malloc(len, M_KENV, M_WAITOK); 277 strcpy(kenvp[i++], cp); 278 } else 279 printf( 280 "WARNING: too many kenv strings, ignoring %s\n", 281 cp); 282 } 283 } 284 kenvp[i] = NULL; 285 286 mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF); 287 dynamic_kenv = 1; 288} 289SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL); 290 291void 292freeenv(char *env) 293{ 294 295 if (dynamic_kenv) 296 free(env, M_KENV); 297} 298 299/* 300 * Internal functions for string lookup. 301 */ 302static char * 303_getenv_dynamic(const char *name, int *idx) 304{ 305 char *cp; 306 int len, i; 307 308 mtx_assert(&kenv_lock, MA_OWNED); 309 len = strlen(name); 310 for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) { 311 if ((strncmp(cp, name, len) == 0) && 312 (cp[len] == '=')) { 313 if (idx != NULL) 314 *idx = i; 315 return (cp + len + 1); 316 } 317 } 318 return (NULL); 319} 320 321static char * 322_getenv_static(const char *name) 323{ 324 char *cp, *ep; 325 int len; 326 327 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) { 328 for (ep = cp; (*ep != '=') && (*ep != 0); ep++) 329 ; 330 if (*ep != '=') 331 continue; 332 len = ep - cp; 333 ep++; 334 if (!strncmp(name, cp, len) && name[len] == 0) 335 return (ep); 336 } 337 return (NULL); 338} 339 340/* 341 * Look up an environment variable by name. 342 * Return a pointer to the string if found. 343 * The pointer has to be freed with freeenv() 344 * after use. 345 */ 346char * 347getenv(const char *name) 348{ 349 char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1]; 350 char *ret; 351 352 if (dynamic_kenv) { 353 if (getenv_string(name, buf, sizeof(buf))) { 354 ret = strdup(buf, M_KENV); 355 } else { 356 ret = NULL; 357 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, 358 "getenv"); 359 } 360 } else 361 ret = _getenv_static(name); 362 return (ret); 363} 364 365/* 366 * Test if an environment variable is defined. 367 */ 368int 369testenv(const char *name) 370{ 371 char *cp; 372 373 if (dynamic_kenv) { 374 mtx_lock(&kenv_lock); 375 cp = _getenv_dynamic(name, NULL); 376 mtx_unlock(&kenv_lock); 377 } else 378 cp = _getenv_static(name); 379 if (cp != NULL) 380 return (1); 381 return (0); 382} 383 384static int 385setenv_static(const char *name, const char *value) 386{ 387 int len; 388 389 if (env_pos >= env_len) 390 return (-1); 391 392 /* Check space for x=y and two nuls */ 393 len = strlen(name) + strlen(value); 394 if (len + 3 < env_len - env_pos) { 395 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value); 396 env_pos += len+1; 397 kern_envp[env_pos] = '\0'; 398 return (0); 399 } else 400 return (-1); 401 402} 403 404/* 405 * Set an environment variable by name. 406 */ 407int 408setenv(const char *name, const char *value) 409{ 410 char *buf, *cp, *oldenv; 411 int namelen, vallen, i; 412 413 if (dynamic_kenv == 0 && env_len > 0) 414 return (setenv_static(name, value)); 415 416 KENV_CHECK; 417 418 namelen = strlen(name) + 1; 419 if (namelen > KENV_MNAMELEN + 1) 420 return (-1); 421 vallen = strlen(value) + 1; 422 if (vallen > KENV_MVALLEN + 1) 423 return (-1); 424 buf = malloc(namelen + vallen, M_KENV, M_WAITOK); 425 sprintf(buf, "%s=%s", name, value); 426 427 mtx_lock(&kenv_lock); 428 cp = _getenv_dynamic(name, &i); 429 if (cp != NULL) { 430 oldenv = kenvp[i]; 431 kenvp[i] = buf; 432 mtx_unlock(&kenv_lock); 433 free(oldenv, M_KENV); 434 } else { 435 /* We add the option if it wasn't found */ 436 for (i = 0; (cp = kenvp[i]) != NULL; i++) 437 ; 438 439 /* Bounds checking */ 440 if (i < 0 || i >= KENV_SIZE) { 441 free(buf, M_KENV); 442 mtx_unlock(&kenv_lock); 443 return (-1); 444 } 445 446 kenvp[i] = buf; 447 kenvp[i + 1] = NULL; 448 mtx_unlock(&kenv_lock); 449 } 450 return (0); 451} 452 453/* 454 * Unset an environment variable string. 455 */ 456int 457unsetenv(const char *name) 458{ 459 char *cp, *oldenv; 460 int i, j; 461 462 KENV_CHECK; 463 464 mtx_lock(&kenv_lock); 465 cp = _getenv_dynamic(name, &i); 466 if (cp != NULL) { 467 oldenv = kenvp[i]; 468 for (j = i + 1; kenvp[j] != NULL; j++) 469 kenvp[i++] = kenvp[j]; 470 kenvp[i] = NULL; 471 mtx_unlock(&kenv_lock); 472 free(oldenv, M_KENV); 473 return (0); 474 } 475 mtx_unlock(&kenv_lock); 476 return (-1); 477} 478 479/* 480 * Return a string value from an environment variable. 481 */ 482int 483getenv_string(const char *name, char *data, int size) 484{ 485 char *cp; 486 487 if (dynamic_kenv) { 488 mtx_lock(&kenv_lock); 489 cp = _getenv_dynamic(name, NULL); 490 if (cp != NULL) 491 strlcpy(data, cp, size); 492 mtx_unlock(&kenv_lock); 493 } else { 494 cp = _getenv_static(name); 495 if (cp != NULL) 496 strlcpy(data, cp, size); 497 } 498 return (cp != NULL); 499} 500 501/* 502 * Return an integer value from an environment variable. 503 */ 504int 505getenv_int(const char *name, int *data) 506{ 507 quad_t tmp; 508 int rval; 509 510 rval = getenv_quad(name, &tmp); 511 if (rval) 512 *data = (int) tmp; 513 return (rval); 514} 515 516/* 517 * Return an unsigned integer value from an environment variable. 518 */ 519int 520getenv_uint(const char *name, unsigned int *data) 521{ 522 quad_t tmp; 523 int rval; 524 525 rval = getenv_quad(name, &tmp); 526 if (rval) 527 *data = (unsigned int) tmp; 528 return (rval); 529} 530 531/* 532 * Return a long value from an environment variable. 533 */ 534int 535getenv_long(const char *name, long *data) 536{ 537 quad_t tmp; 538 int rval; 539 540 rval = getenv_quad(name, &tmp); 541 if (rval) 542 *data = (long) tmp; 543 return (rval); 544} 545 546/* 547 * Return an unsigned long value from an environment variable. 548 */ 549int 550getenv_ulong(const char *name, unsigned long *data) 551{ 552 quad_t tmp; 553 int rval; 554 555 rval = getenv_quad(name, &tmp); 556 if (rval) 557 *data = (unsigned long) tmp; 558 return (rval); 559} 560 561/* 562 * Return a quad_t value from an environment variable. 563 */ 564int 565getenv_quad(const char *name, quad_t *data) 566{ 567 char value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1]; 568 char *vtp; 569 quad_t iv; 570 571 if (!getenv_string(name, value, sizeof(value))) 572 return (0); 573 iv = strtoq(value, &vtp, 0); 574 if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) 575 return (0); 576 switch (vtp[0]) { 577 case 't': case 'T': 578 iv *= 1024; 579 case 'g': case 'G': 580 iv *= 1024; 581 case 'm': case 'M': 582 iv *= 1024; 583 case 'k': case 'K': 584 iv *= 1024; 585 case '\0': 586 break; 587 default: 588 return (0); 589 } 590 *data = iv; 591 return (1); 592} 593 594/* 595 * Find the next entry after the one which (cp) falls within, return a 596 * pointer to its start or NULL if there are no more. 597 */ 598static char * 599kernenv_next(char *cp) 600{ 601 602 if (cp != NULL) { 603 while (*cp != 0) 604 cp++; 605 cp++; 606 if (*cp == 0) 607 cp = NULL; 608 } 609 return (cp); 610} 611 612void 613tunable_int_init(void *data) 614{ 615 struct tunable_int *d = (struct tunable_int *)data; 616 617 TUNABLE_INT_FETCH(d->path, d->var); 618} 619 620void 621tunable_long_init(void *data) 622{ 623 struct tunable_long *d = (struct tunable_long *)data; 624 625 TUNABLE_LONG_FETCH(d->path, d->var); 626} 627 628void 629tunable_ulong_init(void *data) 630{ 631 struct tunable_ulong *d = (struct tunable_ulong *)data; 632 633 TUNABLE_ULONG_FETCH(d->path, d->var); 634} 635 636void 637tunable_quad_init(void *data) 638{ 639 struct tunable_quad *d = (struct tunable_quad *)data; 640 641 TUNABLE_QUAD_FETCH(d->path, d->var); 642} 643 644void 645tunable_str_init(void *data) 646{ 647 struct tunable_str *d = (struct tunable_str *)data; 648 649 TUNABLE_STR_FETCH(d->path, d->var, d->size); 650} 651