kern_environment.c

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    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/8.2/sys/kern/kern_environment.c 199583 2009-11-20 15:27:52Z jhb $");
   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 
   57 static 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 */
   62 char            *kern_envp;
   63 static char     *kernenv_next(char *);
   64 
   65 /* dynamic environment variables */
   66 char            **kenvp;
   67 struct mtx      kenv_lock;
   68 
   69 /*
   70  * No need to protect this with a mutex since SYSINITS are single threaded.
   71  */
   72 int     dynamic_kenv = 0;
   73 
   74 #define KENV_CHECK      if (!dynamic_kenv) \
   75                             panic("%s: called before SI_SUB_KMEM", __func__)
   76 
   77 int
   78 kenv(td, uap)
   79         struct thread *td;
   80         struct kenv_args /* {
   81                 int what;
   82                 const char *name;
   83                 char *value;
   84                 int len;
   85         } */ *uap;
   86 {
   87         char *name, *value, *buffer = NULL;
   88         size_t len, done, needed, buflen;
   89         int error, i;
   90 
   91         KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = 0"));
   92 
   93         error = 0;
   94         if (uap->what == KENV_DUMP) {
   95 #ifdef MAC
   96                 error = mac_kenv_check_dump(td->td_ucred);
   97                 if (error)
   98                         return (error);
   99 #endif
  100                 done = needed = 0;
  101                 buflen = uap->len;
  102                 if (buflen > KENV_SIZE * (KENV_MNAMELEN + KENV_MVALLEN + 2))
  103                         buflen = KENV_SIZE * (KENV_MNAMELEN +
  104                             KENV_MVALLEN + 2);
  105                 if (uap->len > 0 && uap->value != NULL)
  106                         buffer = malloc(buflen, M_TEMP, M_WAITOK|M_ZERO);
  107                 mtx_lock(&kenv_lock);
  108                 for (i = 0; kenvp[i] != NULL; i++) {
  109                         len = strlen(kenvp[i]) + 1;
  110                         needed += len;
  111                         len = min(len, buflen - done);
  112                         /*
  113                          * If called with a NULL or insufficiently large
  114                          * buffer, just keep computing the required size.
  115                          */
  116                         if (uap->value != NULL && buffer != NULL && len > 0) {
  117                                 bcopy(kenvp[i], buffer + done, len);
  118                                 done += len;
  119                         }
  120                 }
  121                 mtx_unlock(&kenv_lock);
  122                 if (buffer != NULL) {
  123                         error = copyout(buffer, uap->value, done);
  124                         free(buffer, M_TEMP);
  125                 }
  126                 td->td_retval[0] = ((done == needed) ? 0 : needed);
  127                 return (error);
  128         }
  129 
  130         switch (uap->what) {
  131         case KENV_SET:
  132                 error = priv_check(td, PRIV_KENV_SET);
  133                 if (error)
  134                         return (error);
  135                 break;
  136 
  137         case KENV_UNSET:
  138                 error = priv_check(td, PRIV_KENV_UNSET);
  139                 if (error)
  140                         return (error);
  141                 break;
  142         }
  143 
  144         name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
  145 
  146         error = copyinstr(uap->name, name, KENV_MNAMELEN, NULL);
  147         if (error)
  148                 goto done;
  149 
  150         switch (uap->what) {
  151         case KENV_GET:
  152 #ifdef MAC
  153                 error = mac_kenv_check_get(td->td_ucred, name);
  154                 if (error)
  155                         goto done;
  156 #endif
  157                 value = getenv(name);
  158                 if (value == NULL) {
  159                         error = ENOENT;
  160                         goto done;
  161                 }
  162                 len = strlen(value) + 1;
  163                 if (len > uap->len)
  164                         len = uap->len;
  165                 error = copyout(value, uap->value, len);
  166                 freeenv(value);
  167                 if (error)
  168                         goto done;
  169                 td->td_retval[0] = len;
  170                 break;
  171         case KENV_SET:
  172                 len = uap->len;
  173                 if (len < 1) {
  174                         error = EINVAL;
  175                         goto done;
  176                 }
  177                 if (len > KENV_MVALLEN)
  178                         len = KENV_MVALLEN;
  179                 value = malloc(len, M_TEMP, M_WAITOK);
  180                 error = copyinstr(uap->value, value, len, NULL);
  181                 if (error) {
  182                         free(value, M_TEMP);
  183                         goto done;
  184                 }
  185 #ifdef MAC
  186                 error = mac_kenv_check_set(td->td_ucred, name, value);
  187                 if (error == 0)
  188 #endif
  189                         setenv(name, value);
  190                 free(value, M_TEMP);
  191                 break;
  192         case KENV_UNSET:
  193 #ifdef MAC
  194                 error = mac_kenv_check_unset(td->td_ucred, name);
  195                 if (error)
  196                         goto done;
  197 #endif
  198                 error = unsetenv(name);
  199                 if (error)
  200                         error = ENOENT;
  201                 break;
  202         default:
  203                 error = EINVAL;
  204                 break;
  205         }
  206 done:
  207         free(name, M_TEMP);
  208         return (error);
  209 }
  210 
  211 /*
  212  * Setup the dynamic kernel environment.
  213  */
  214 static void
  215 init_dynamic_kenv(void *data __unused)
  216 {
  217         char *cp;
  218         int len, i;
  219 
  220         kenvp = malloc((KENV_SIZE + 1) * sizeof(char *), M_KENV,
  221                 M_WAITOK | M_ZERO);
  222         i = 0;
  223         for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
  224                 len = strlen(cp) + 1;
  225                 if (i < KENV_SIZE) {
  226                         kenvp[i] = malloc(len, M_KENV, M_WAITOK);
  227                         strcpy(kenvp[i++], cp);
  228                 } else
  229                         printf(
  230                             "WARNING: too many kenv strings, ignoring %s\n",
  231                             cp);
  232         }
  233         kenvp[i] = NULL;
  234 
  235         mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
  236         dynamic_kenv = 1;
  237 }
  238 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
  239 
  240 void
  241 freeenv(char *env)
  242 {
  243 
  244         if (dynamic_kenv)
  245                 free(env, M_KENV);
  246 }
  247 
  248 /*
  249  * Internal functions for string lookup.
  250  */
  251 static char *
  252 _getenv_dynamic(const char *name, int *idx)
  253 {
  254         char *cp;
  255         int len, i;
  256 
  257         mtx_assert(&kenv_lock, MA_OWNED);
  258         len = strlen(name);
  259         for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
  260                 if ((strncmp(cp, name, len) == 0) &&
  261                     (cp[len] == '=')) {
  262                         if (idx != NULL)
  263                                 *idx = i;
  264                         return (cp + len + 1);
  265                 }
  266         }
  267         return (NULL);
  268 }
  269 
  270 static char *
  271 _getenv_static(const char *name)
  272 {
  273         char *cp, *ep;
  274         int len;
  275 
  276         for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
  277                 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
  278                         ;
  279                 if (*ep != '=')
  280                         continue;
  281                 len = ep - cp;
  282                 ep++;
  283                 if (!strncmp(name, cp, len) && name[len] == 0)
  284                         return (ep);
  285         }
  286         return (NULL);
  287 }
  288 
  289 /*
  290  * Look up an environment variable by name.
  291  * Return a pointer to the string if found.
  292  * The pointer has to be freed with freeenv()
  293  * after use.
  294  */
  295 char *
  296 getenv(const char *name)
  297 {
  298         char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
  299         char *ret, *cp;
  300         int len;
  301 
  302         if (dynamic_kenv) {
  303                 mtx_lock(&kenv_lock);
  304                 cp = _getenv_dynamic(name, NULL);
  305                 if (cp != NULL) {
  306                         strcpy(buf, cp);
  307                         mtx_unlock(&kenv_lock);
  308                         len = strlen(buf) + 1;
  309                         ret = malloc(len, M_KENV, M_WAITOK);
  310                         strcpy(ret, buf);
  311                 } else {
  312                         mtx_unlock(&kenv_lock);
  313                         ret = NULL;
  314                 }
  315         } else
  316                 ret = _getenv_static(name);
  317         return (ret);
  318 }
  319 
  320 /*
  321  * Test if an environment variable is defined.
  322  */
  323 int
  324 testenv(const char *name)
  325 {
  326         char *cp;
  327 
  328         if (dynamic_kenv) {
  329                 mtx_lock(&kenv_lock);
  330                 cp = _getenv_dynamic(name, NULL);
  331                 mtx_unlock(&kenv_lock);
  332         } else
  333                 cp = _getenv_static(name);
  334         if (cp != NULL)
  335                 return (1);
  336         return (0);
  337 }
  338 
  339 /*
  340  * Set an environment variable by name.
  341  */
  342 int
  343 setenv(const char *name, const char *value)
  344 {
  345         char *buf, *cp, *oldenv;
  346         int namelen, vallen, i;
  347 
  348         KENV_CHECK;
  349 
  350         namelen = strlen(name) + 1;
  351         if (namelen > KENV_MNAMELEN)
  352                 return (-1);
  353         vallen = strlen(value) + 1;
  354         if (vallen > KENV_MVALLEN)
  355                 return (-1);
  356         buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
  357         sprintf(buf, "%s=%s", name, value);
  358 
  359         mtx_lock(&kenv_lock);
  360         cp = _getenv_dynamic(name, &i);
  361         if (cp != NULL) {
  362                 oldenv = kenvp[i];
  363                 kenvp[i] = buf;
  364                 mtx_unlock(&kenv_lock);
  365                 free(oldenv, M_KENV);
  366         } else {
  367                 /* We add the option if it wasn't found */
  368                 for (i = 0; (cp = kenvp[i]) != NULL; i++)
  369                         ;
  370 
  371                 /* Bounds checking */
  372                 if (i < 0 || i >= KENV_SIZE) {
  373                         free(buf, M_KENV);
  374                         mtx_unlock(&kenv_lock);
  375                         return (-1);
  376                 }
  377 
  378                 kenvp[i] = buf;
  379                 kenvp[i + 1] = NULL;
  380                 mtx_unlock(&kenv_lock);
  381         }
  382         return (0);
  383 }
  384 
  385 /*
  386  * Unset an environment variable string.
  387  */
  388 int
  389 unsetenv(const char *name)
  390 {
  391         char *cp, *oldenv;
  392         int i, j;
  393 
  394         KENV_CHECK;
  395 
  396         mtx_lock(&kenv_lock);
  397         cp = _getenv_dynamic(name, &i);
  398         if (cp != NULL) {
  399                 oldenv = kenvp[i];
  400                 for (j = i + 1; kenvp[j] != NULL; j++)
  401                         kenvp[i++] = kenvp[j];
  402                 kenvp[i] = NULL;
  403                 mtx_unlock(&kenv_lock);
  404                 free(oldenv, M_KENV);
  405                 return (0);
  406         }
  407         mtx_unlock(&kenv_lock);
  408         return (-1);
  409 }
  410 
  411 /*
  412  * Return a string value from an environment variable.
  413  */
  414 int
  415 getenv_string(const char *name, char *data, int size)
  416 {
  417         char *tmp;
  418 
  419         tmp = getenv(name);
  420         if (tmp != NULL) {
  421                 strlcpy(data, tmp, size);
  422                 freeenv(tmp);
  423                 return (1);
  424         } else
  425                 return (0);
  426 }
  427 
  428 /*
  429  * Return an integer value from an environment variable.
  430  */
  431 int
  432 getenv_int(const char *name, int *data)
  433 {
  434         quad_t tmp;
  435         int rval;
  436 
  437         rval = getenv_quad(name, &tmp);
  438         if (rval)
  439                 *data = (int) tmp;
  440         return (rval);
  441 }
  442 
  443 /*
  444  * Return an unsigned integer value from an environment variable.
  445  */
  446 int
  447 getenv_uint(const char *name, unsigned int *data)
  448 {
  449         quad_t tmp;
  450         int rval;
  451 
  452         rval = getenv_quad(name, &tmp);
  453         if (rval)
  454                 *data = (unsigned int) tmp;
  455         return (rval);
  456 }
  457 
  458 /*
  459  * Return a long value from an environment variable.
  460  */
  461 int
  462 getenv_long(const char *name, long *data)
  463 {
  464         quad_t tmp;
  465         int rval;
  466 
  467         rval = getenv_quad(name, &tmp);
  468         if (rval)
  469                 *data = (long) tmp;
  470         return (rval);
  471 }
  472 
  473 /*
  474  * Return an unsigned long value from an environment variable.
  475  */
  476 int
  477 getenv_ulong(const char *name, unsigned long *data)
  478 {
  479         quad_t tmp;
  480         int rval;
  481 
  482         rval = getenv_quad(name, &tmp);
  483         if (rval)
  484                 *data = (unsigned long) tmp;
  485         return (rval);
  486 }
  487 
  488 /*
  489  * Return a quad_t value from an environment variable.
  490  */
  491 int
  492 getenv_quad(const char *name, quad_t *data)
  493 {
  494         char    *value;
  495         char    *vtp;
  496         quad_t  iv;
  497 
  498         value = getenv(name);
  499         if (value == NULL)
  500                 return (0);
  501         iv = strtoq(value, &vtp, 0);
  502         if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0')) {
  503                 freeenv(value);
  504                 return (0);
  505         }
  506         switch (vtp[0]) {
  507         case 't': case 'T':
  508                 iv *= 1024;
  509         case 'g': case 'G':
  510                 iv *= 1024;
  511         case 'm': case 'M':
  512                 iv *= 1024;
  513         case 'k': case 'K':
  514                 iv *= 1024;
  515         case '\0':
  516                 break;
  517         default:
  518                 freeenv(value);
  519                 return (0);
  520         }
  521         *data = iv;
  522         freeenv(value);
  523         return (1);
  524 }
  525 
  526 /*
  527  * Find the next entry after the one which (cp) falls within, return a
  528  * pointer to its start or NULL if there are no more.
  529  */
  530 static char *
  531 kernenv_next(char *cp)
  532 {
  533 
  534         if (cp != NULL) {
  535                 while (*cp != 0)
  536                         cp++;
  537                 cp++;
  538                 if (*cp == 0)
  539                         cp = NULL;
  540         }
  541         return (cp);
  542 }
  543 
  544 void
  545 tunable_int_init(void *data)
  546 {
  547         struct tunable_int *d = (struct tunable_int *)data;
  548 
  549         TUNABLE_INT_FETCH(d->path, d->var);
  550 }
  551 
  552 void
  553 tunable_long_init(void *data)
  554 {
  555         struct tunable_long *d = (struct tunable_long *)data;
  556 
  557         TUNABLE_LONG_FETCH(d->path, d->var);
  558 }
  559 
  560 void
  561 tunable_ulong_init(void *data)
  562 {
  563         struct tunable_ulong *d = (struct tunable_ulong *)data;
  564 
  565         TUNABLE_ULONG_FETCH(d->path, d->var);
  566 }
  567 
  568 void
  569 tunable_quad_init(void *data)
  570 {
  571         struct tunable_quad *d = (struct tunable_quad *)data;
  572 
  573         TUNABLE_QUAD_FETCH(d->path, d->var);
  574 }
  575 
  576 void
  577 tunable_str_init(void *data)
  578 {
  579         struct tunable_str *d = (struct tunable_str *)data;
  580 
  581         TUNABLE_STR_FETCH(d->path, d->var, d->size);
  582 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_environment.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_environment.c
