sys/kern/kern_environment.c

   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("$FreeBSD$");
  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/malloc.h>
  48 #include <sys/mutex.h>
  49 #include <sys/priv.h>
  50 #include <sys/kernel.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
  57 #include <security/mac/mac_framework.h>
  58
  59 static MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
  60
  61 #define KENV_SIZE       512     /* Maximum number of environment strings */
  62
  63 /* pointer to the static environment */
  64 char            *kern_envp;
  65 static char     *kernenv_next(char *);
  66
  67 /* dynamic environment variables */
  68 char            **kenvp;
  69 struct mtx      kenv_lock;
  70
  71 /*
  72  * No need to protect this with a mutex 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, *buffer = NULL;
  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_kenv_check_dump(td->td_ucred);
  99                 if (error)
 100                         return (error);
 101 #endif
 102                 done = needed = 0;
 103                 if (uap->len > 0 && uap->value != NULL)
 104                         buffer = malloc(uap->len, M_TEMP, M_WAITOK|M_ZERO);
 105                 mtx_lock(&kenv_lock);
 106                 for (i = 0; kenvp[i] != NULL; i++) {
 107                         len = strlen(kenvp[i]) + 1;
 108                         needed += len;
 109                         len = min(len, uap->len - done);
 110                         /*
 111                          * If called with a NULL or insufficiently large
 112                          * buffer, just keep computing the required size.
 113                          */
 114                         if (uap->value != NULL && buffer != NULL && len > 0) {
 115                                 bcopy(kenvp[i], buffer + done, len);
 116                                 done += len;
 117                         }
 118                 }
 119                 mtx_unlock(&kenv_lock);
 120                 if (buffer != NULL) {
 121                         error = copyout(buffer, uap->value, done);
 122                         free(buffer, M_TEMP);
 123                 }
 124                 td->td_retval[0] = ((done == needed) ? 0 : needed);
 125                 return (error);
 126         }
 127
 128         switch (uap->what) {
 129         case KENV_SET:
 130                 error = priv_check(td, PRIV_KENV_SET);
 131                 if (error)
 132                         return (error);
 133                 break;
 134
 135         case KENV_UNSET:
 136                 error = priv_check(td, PRIV_KENV_UNSET);
 137                 if (error)
 138                         return (error);
 139                 break;
 140         }
 141
 142         name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
 143
 144         error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
 145         if (error)
 146                 goto done;
 147
 148         switch (uap->what) {
 149         case KENV_GET:
 150 #ifdef MAC
 151                 error = mac_kenv_check_get(td->td_ucred, name);
 152                 if (error)
 153                         goto done;
 154 #endif
 155                 value = getenv(name);
 156                 if (value == NULL) {
 157                         error = ENOENT;
 158                         goto done;
 159                 }
 160                 len = strlen(value) + 1;
 161                 if (len > uap->len)
 162                         len = uap->len;
 163                 error = copyout(value, uap->value, len);
 164                 freeenv(value);
 165                 if (error)
 166                         goto done;
 167                 td->td_retval[0] = len;
 168                 break;
 169         case KENV_SET:
 170                 len = uap->len;
 171                 if (len < 1) {
 172                         error = EINVAL;
 173                         goto done;
 174                 }
 175                 if (len > KENV_MVALLEN)
 176                         len = KENV_MVALLEN;
 177                 value = malloc(len, M_TEMP, M_WAITOK);
 178                 error = copyinstr(uap->value, value, len, NULL);
 179                 if (error) {
 180                         free(value, M_TEMP);
 181                         goto done;
 182                 }
 183 #ifdef MAC
 184                 error = mac_kenv_check_set(td->td_ucred, name, value);
 185                 if (error == 0)
 186 #endif
 187                         setenv(name, value);
 188                 free(value, M_TEMP);
 189                 break;
 190         case KENV_UNSET:
 191 #ifdef MAC
 192                 error = mac_kenv_check_unset(td->td_ucred, name);
 193                 if (error)
 194                         goto done;
 195 #endif
 196                 error = unsetenv(name);
 197                 if (error)
 198                         error = ENOENT;
 199                 break;
 200         default:
 201                 error = EINVAL;
 202                 break;
 203         }
 204 done:
 205         free(name, M_TEMP);
 206         return (error);
 207 }
 208
 209 /*
 210  * Setup the dynamic kernel environment.
 211  */
 212 static void
 213 init_dynamic_kenv(void *data __unused)
 214 {
 215         char *cp;
 216         int len, i;
 217
 218         kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
 219                 M_WAITOK | M_ZERO);
 220         i = 0;
 221         for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
 222                 len = strlen(cp) + 1;
 223                 if (i < KENV_SIZE) {
 224                         kenvp[i] = malloc(len, M_KENV, M_WAITOK);
 225                         strcpy(kenvp[i++], cp);
 226                 } else
 227                         printf(
 228                             "WARNING: too many kenv strings, ignoring %s\n",
 229                             cp);
 230         }
 231         kenvp[i] = NULL;
 232
 233         mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
 234         dynamic_kenv = 1;
 235 }
 236 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
 237
 238 void
 239 freeenv(char *env)
 240 {
 241
 242         if (dynamic_kenv)
 243                 free(env, M_KENV);
 244 }
 245
 246 /*
 247  * Internal functions for string lookup.
 248  */
 249 static char *
 250 _getenv_dynamic(const char *name, int *idx)
 251 {
 252         char *cp;
 253         int len, i;
 254
 255         mtx_assert(&kenv_lock, MA_OWNED);
 256         len = strlen(name);
 257         for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
 258                 if ((strncmp(cp, name, len) == 0) &&
 259                     (cp[len] == '=')) {
 260                         if (idx != NULL)
 261                                 *idx = i;
 262                         return (cp + len + 1);
 263                 }
 264         }
 265         return (NULL);
 266 }
 267
 268 static char *
 269 _getenv_static(const char *name)
 270 {
 271         char *cp, *ep;
 272         int len;
 273
 274         for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
 275                 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
 276                         ;
 277                 if (*ep != '=')
 278                         continue;
 279                 len = ep - cp;
 280                 ep++;
 281                 if (!strncmp(name, cp, len) && name[len] == 0)
 282                         return (ep);
 283         }
 284         return (NULL);
 285 }
 286
 287 /*
 288  * Look up an environment variable by name.
 289  * Return a pointer to the string if found.
 290  * The pointer has to be freed with freeenv()
 291  * after use.
 292  */
 293 char *
 294 getenv(const char *name)
 295 {
 296         char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
 297         char *ret, *cp;
 298         int len;
 299
 300         if (dynamic_kenv) {
 301                 mtx_lock(&kenv_lock);
 302                 cp = _getenv_dynamic(name, NULL);
 303                 if (cp != NULL) {
 304                         strcpy(buf, cp);
 305                         mtx_unlock(&kenv_lock);
 306                         len = strlen(buf) + 1;
 307                         ret = malloc(len, M_KENV, M_WAITOK);
 308                         strcpy(ret, buf);
 309                 } else {
 310                         mtx_unlock(&kenv_lock);
 311                         ret = NULL;
 312                 }
 313         } else
 314                 ret = _getenv_static(name);
 315         return (ret);
 316 }
 317
 318 /*
 319  * Test if an environment variable is defined.
 320  */
 321 int
 322 testenv(const char *name)
 323 {
 324         char *cp;
 325
 326         if (dynamic_kenv) {
 327                 mtx_lock(&kenv_lock);
 328                 cp = _getenv_dynamic(name, NULL);
 329                 mtx_unlock(&kenv_lock);
 330         } else
 331                 cp = _getenv_static(name);
 332         if (cp != NULL)
 333                 return (1);
 334         return (0);
 335 }
 336
 337 /*
 338  * Set an environment variable by name.
 339  */
 340 int
 341 setenv(const char *name, const char *value)
 342 {
 343         char *buf, *cp, *oldenv;
 344         int namelen, vallen, i;
 345
 346         KENV_CHECK;
 347
 348         namelen = strlen(name) + 1;
 349         if (namelen > KENV_MNAMELEN)
 350                 return (-1);
 351         vallen = strlen(value) + 1;
 352         if (vallen > KENV_MVALLEN)
 353                 return (-1);
 354         buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
 355         sprintf(buf, "%s=%s", name, value);
 356
 357         mtx_lock(&kenv_lock);
 358         cp = _getenv_dynamic(name, &i);
 359         if (cp != NULL) {
 360                 oldenv = kenvp[i];
 361                 kenvp[i] = buf;
 362                 mtx_unlock(&kenv_lock);
 363                 free(oldenv, M_KENV);
 364         } else {
 365                 /* We add the option if it wasn't found */
 366                 for (i = 0; (cp = kenvp[i]) != NULL; i++)
 367                         ;
 368
 369                 /* Bounds checking */
 370                 if (i < 0 || i >= KENV_SIZE) {
 371                         free(buf, M_KENV);
 372                         mtx_unlock(&kenv_lock);
 373                         return (-1);
 374                 }
 375
 376                 kenvp[i] = buf;
 377                 kenvp[i + 1] = NULL;
 378                 mtx_unlock(&kenv_lock);
 379         }
 380         return (0);
 381 }
 382
 383 /*
 384  * Unset an environment variable string.
 385  */
 386 int
 387 unsetenv(const char *name)
 388 {
 389         char *cp, *oldenv;
 390         int i, j;
 391
 392         KENV_CHECK;
 393
 394         mtx_lock(&kenv_lock);
 395         cp = _getenv_dynamic(name, &i);
 396         if (cp != NULL) {
 397                 oldenv = kenvp[i];
 398                 for (j = i + 1; kenvp[j] != NULL; j++)
 399                         kenvp[i++] = kenvp[j];
 400                 kenvp[i] = NULL;
 401                 mtx_unlock(&kenv_lock);
 402                 free(oldenv, M_KENV);
 403                 return (0);
 404         }
 405         mtx_unlock(&kenv_lock);
 406         return (-1);
 407 }
 408
 409 /*
 410  * Return a string value from an environment variable.
 411  */
 412 int
 413 getenv_string(const char *name, char *data, int size)
 414 {
 415         char *tmp;
 416
 417         tmp = getenv(name);
 418         if (tmp != NULL) {
 419                 strlcpy(data, tmp, size);
 420                 freeenv(tmp);
 421                 return (1);
 422         } else
 423                 return (0);
 424 }
 425
 426 /*
 427  * Return an integer value from an environment variable.
 428  */
 429 int
 430 getenv_int(const char *name, int *data)
 431 {
 432         quad_t tmp;
 433         int rval;
 434
 435         rval = getenv_quad(name, &tmp);
 436         if (rval)
 437                 *data = (int) tmp;
 438         return (rval);
 439 }
 440
 441 /*
 442  * Return an unsigned integer value from an environment variable.
 443  */
 444 int
 445 getenv_uint(const char *name, unsigned int *data)
 446 {
 447         quad_t tmp;
 448         int rval;
 449
 450         rval = getenv_quad(name, &tmp);
 451         if (rval)
 452                 *data = (unsigned int) tmp;
 453         return (rval);
 454 }
 455
 456 /*
 457  * Return a long value from an environment variable.
 458  */
 459 int
 460 getenv_long(const char *name, long *data)
 461 {
 462         quad_t tmp;
 463         int rval;
 464
 465         rval = getenv_quad(name, &tmp);
 466         if (rval)
 467                 *data = (long) tmp;
 468         return (rval);
 469 }
 470
 471 /*
 472  * Return an unsigned long value from an environment variable.
 473  */
 474 int
 475 getenv_ulong(const char *name, unsigned long *data)
 476 {
 477         quad_t tmp;
 478         int rval;
 479
 480         rval = getenv_quad(name, &tmp);
 481         if (rval)
 482                 *data = (unsigned long) tmp;
 483         return (rval);
 484 }
 485
 486 /*
 487  * Return a quad_t value from an environment variable.
 488  */
 489 int
 490 getenv_quad(const char *name, quad_t *data)
 491 {
 492         char    *value;
 493         char    *vtp;
 494         quad_t  iv;
 495
 496         value = getenv(name);
 497         if (value == NULL)
 498                 return (0);
 499         iv = strtoq(value, &vtp, 0);
 500         if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
 501                 freeenv(value);
 502                 return (0);
 503         }
 504         switch (vtp[0]) {
 505         case 't': case 'T':
 506                 iv *= 1024;
 507         case 'g': case 'G':
 508                 iv *= 1024;
 509         case 'm': case 'M':
 510                 iv *= 1024;
 511         case 'k': case 'K':
 512                 iv *= 1024;
 513         case '\0':
 514                 break;
 515         default:
 516                 freeenv(value);
 517                 return (0);
 518         }
 519         *data = iv;
 520         freeenv(value);
 521         return (1);
 522 }
 523
 524 /*
 525  * Find the next entry after the one which (cp) falls within, return a
 526  * pointer to its start or NULL if there are no more.
 527  */
 528 static char *
 529 kernenv_next(char *cp)
 530 {
 531
 532         if (cp != NULL) {
 533                 while (*cp != 0)
 534                         cp++;
 535                 cp++;
 536                 if (*cp == 0)
 537                         cp = NULL;
 538         }
 539         return (cp);
 540 }
 541
 542 void
 543 tunable_int_init(void *data)
 544 {
 545         struct tunable_int *d = (struct tunable_int *)data;
 546
 547         TUNABLE_INT_FETCH(d->path, d->var);
 548 }
 549
 550 void
 551 tunable_long_init(void *data)
 552 {
 553         struct tunable_long *d = (struct tunable_long *)data;
 554
 555         TUNABLE_LONG_FETCH(d->path, d->var);
 556 }
 557
 558 void
 559 tunable_ulong_init(void *data)
 560 {
 561         struct tunable_ulong *d = (struct tunable_ulong *)data;
 562
 563         TUNABLE_ULONG_FETCH(d->path, d->var);
 564 }
 565
 566 void
 567 tunable_quad_init(void *data)
 568 {
 569         struct tunable_quad *d = (struct tunable_quad *)data;
 570
 571         TUNABLE_QUAD_FETCH(d->path, d->var);
 572 }
 573
 574 void
 575 tunable_str_init(void *data)
 576 {
 577         struct tunable_str *d = (struct tunable_str *)data;
 578
 579         TUNABLE_STR_FETCH(d->path, d->var, d->size);
 580 }