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/10.1/sys/kern/kern_environment.c 260387 2014-01-07 01:51:48Z scottl $");
   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 int      env_len;
   64 static int      env_pos;
   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 sys_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         }
  208 done:
  209         free(name, M_TEMP);
  210         return (error);
  211 }
  212 
  213 void
  214 init_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  */
  224 static void
  225 init_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         if (kern_envp && *kern_envp != '\0') {
  235                 for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
  236                         len = strlen(cp) + 1;
  237                         if (len > KENV_MNAMELEN + 1 + KENV_MVALLEN + 1) {
  238                                 printf(
  239                                 "WARNING: too long kenv string, ignoring %s\n",
  240                                     cp);
  241                                 continue;
  242                         }
  243                         if (i < KENV_SIZE) {
  244                                 kenvp[i] = malloc(len, M_KENV, M_WAITOK);
  245                                 strcpy(kenvp[i++], cp);
  246                         } else
  247                                 printf(
  248                                 "WARNING: too many kenv strings, ignoring %s\n",
  249                                     cp);
  250                 }
  251         }
  252         kenvp[i] = NULL;
  253 
  254         mtx_init(&kenv_lock, "kernel environment", NULL, MTX_DEF);
  255         dynamic_kenv = 1;
  256 }
  257 SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
  258 
  259 void
  260 freeenv(char *env)
  261 {
  262 
  263         if (dynamic_kenv)
  264                 free(env, M_KENV);
  265 }
  266 
  267 /*
  268  * Internal functions for string lookup.
  269  */
  270 static char *
  271 _getenv_dynamic(const char *name, int *idx)
  272 {
  273         char *cp;
  274         int len, i;
  275 
  276         mtx_assert(&kenv_lock, MA_OWNED);
  277         len = strlen(name);
  278         for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
  279                 if ((strncmp(cp, name, len) == 0) &&
  280                     (cp[len] == '=')) {
  281                         if (idx != NULL)
  282                                 *idx = i;
  283                         return (cp + len + 1);
  284                 }
  285         }
  286         return (NULL);
  287 }
  288 
  289 static char *
  290 _getenv_static(const char *name)
  291 {
  292         char *cp, *ep;
  293         int len;
  294 
  295         for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
  296                 for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
  297                         ;
  298                 if (*ep != '=')
  299                         continue;
  300                 len = ep - cp;
  301                 ep++;
  302                 if (!strncmp(name, cp, len) && name[len] == 0)
  303                         return (ep);
  304         }
  305         return (NULL);
  306 }
  307 
  308 /*
  309  * Look up an environment variable by name.
  310  * Return a pointer to the string if found.
  311  * The pointer has to be freed with freeenv()
  312  * after use.
  313  */
  314 char *
  315 getenv(const char *name)
  316 {
  317         char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
  318         char *ret;
  319 
  320         if (dynamic_kenv) {
  321                 if (getenv_string(name, buf, sizeof(buf))) {
  322                         ret = strdup(buf, M_KENV);
  323                 } else {
  324                         ret = NULL;
  325                         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
  326                             "getenv");
  327                 }
  328         } else
  329                 ret = _getenv_static(name);
  330         return (ret);
  331 }
  332 
  333 /*
  334  * Test if an environment variable is defined.
  335  */
  336 int
  337 testenv(const char *name)
  338 {
  339         char *cp;
  340 
  341         if (dynamic_kenv) {
  342                 mtx_lock(&kenv_lock);
  343                 cp = _getenv_dynamic(name, NULL);
  344                 mtx_unlock(&kenv_lock);
  345         } else
  346                 cp = _getenv_static(name);
  347         if (cp != NULL)
  348                 return (1);
  349         return (0);
  350 }
  351 
  352 static int
  353 setenv_static(const char *name, const char *value)
  354 {
  355         int len;
  356 
  357         if (env_pos >= env_len)
  358                 return (-1);
  359 
  360         /* Check space for x=y and two nuls */
  361         len = strlen(name) + strlen(value);
  362         if (len + 3 < env_len - env_pos) {
  363                 len = sprintf(&kern_envp[env_pos], "%s=%s", name, value);
  364                 env_pos += len+1;
  365                 kern_envp[env_pos] = '\0';
  366                 return (0);
  367         } else
  368                 return (-1);
  369 
  370 }
  371 
  372 /*
  373  * Set an environment variable by name.
  374  */
  375 int
  376 setenv(const char *name, const char *value)
  377 {
  378         char *buf, *cp, *oldenv;
  379         int namelen, vallen, i;
  380 
  381         if (dynamic_kenv == 0 && env_len > 0)
  382                 return (setenv_static(name, value));
  383 
  384         KENV_CHECK;
  385 
  386         namelen = strlen(name) + 1;
  387         if (namelen > KENV_MNAMELEN + 1)
  388                 return (-1);
  389         vallen = strlen(value) + 1;
  390         if (vallen > KENV_MVALLEN + 1)
  391                 return (-1);
  392         buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
  393         sprintf(buf, "%s=%s", name, value);
  394 
  395         mtx_lock(&kenv_lock);
  396         cp = _getenv_dynamic(name, &i);
  397         if (cp != NULL) {
  398                 oldenv = kenvp[i];
  399                 kenvp[i] = buf;
  400                 mtx_unlock(&kenv_lock);
  401                 free(oldenv, M_KENV);
  402         } else {
  403                 /* We add the option if it wasn't found */
  404                 for (i = 0; (cp = kenvp[i]) != NULL; i++)
  405                         ;
  406 
  407                 /* Bounds checking */
  408                 if (i < 0 || i >= KENV_SIZE) {
  409                         free(buf, M_KENV);
  410                         mtx_unlock(&kenv_lock);
  411                         return (-1);
  412                 }
  413 
  414                 kenvp[i] = buf;
  415                 kenvp[i + 1] = NULL;
  416                 mtx_unlock(&kenv_lock);
  417         }
  418         return (0);
  419 }
  420 
  421 /*
  422  * Unset an environment variable string.
  423  */
  424 int
  425 unsetenv(const char *name)
  426 {
  427         char *cp, *oldenv;
  428         int i, j;
  429 
  430         KENV_CHECK;
  431 
  432         mtx_lock(&kenv_lock);
  433         cp = _getenv_dynamic(name, &i);
  434         if (cp != NULL) {
  435                 oldenv = kenvp[i];
  436                 for (j = i + 1; kenvp[j] != NULL; j++)
  437                         kenvp[i++] = kenvp[j];
  438                 kenvp[i] = NULL;
  439                 mtx_unlock(&kenv_lock);
  440                 free(oldenv, M_KENV);
  441                 return (0);
  442         }
  443         mtx_unlock(&kenv_lock);
  444         return (-1);
  445 }
  446 
  447 /*
  448  * Return a string value from an environment variable.
  449  */
  450 int
  451 getenv_string(const char *name, char *data, int size)
  452 {
  453         char *cp;
  454 
  455         if (dynamic_kenv) {
  456                 mtx_lock(&kenv_lock);
  457                 cp = _getenv_dynamic(name, NULL);
  458                 if (cp != NULL)
  459                         strlcpy(data, cp, size);
  460                 mtx_unlock(&kenv_lock);
  461         } else {
  462                 cp = _getenv_static(name);
  463                 if (cp != NULL)
  464                         strlcpy(data, cp, size);
  465         }
  466         return (cp != NULL);
  467 }
  468 
  469 /*
  470  * Return an integer value from an environment variable.
  471  */
  472 int
  473 getenv_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  */
  487 int
  488 getenv_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  */
  502 int
  503 getenv_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  */
  517 int
  518 getenv_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  */
  532 int
  533 getenv_quad(const char *name, quad_t *data)
  534 {
  535         char    value[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
  536         char    *vtp;
  537         quad_t  iv;
  538 
  539         if (!getenv_string(name, value, sizeof(value)))
  540                 return (0);
  541         iv = strtoq(value, &vtp, 0);
  542         if (vtp == value || (vtp[0] != '\0' && vtp[1] != '\0'))
  543                 return (0);
  544         switch (vtp[0]) {
  545         case 't': case 'T':
  546                 iv *= 1024;
  547         case 'g': case 'G':
  548                 iv *= 1024;
  549         case 'm': case 'M':
  550                 iv *= 1024;
  551         case 'k': case 'K':
  552                 iv *= 1024;
  553         case '\0':
  554                 break;
  555         default:
  556                 return (0);
  557         }
  558         *data = iv;
  559         return (1);
  560 }
  561 
  562 /*
  563  * Find the next entry after the one which (cp) falls within, return a
  564  * pointer to its start or NULL if there are no more.
  565  */
  566 static char *
  567 kernenv_next(char *cp)
  568 {
  569 
  570         if (cp != NULL) {
  571                 while (*cp != 0)
  572                         cp++;
  573                 cp++;
  574                 if (*cp == 0)
  575                         cp = NULL;
  576         }
  577         return (cp);
  578 }
  579 
  580 void
  581 tunable_int_init(void *data)
  582 {
  583         struct tunable_int *d = (struct tunable_int *)data;
  584 
  585         TUNABLE_INT_FETCH(d->path, d->var);
  586 }
  587 
  588 void
  589 tunable_long_init(void *data)
  590 {
  591         struct tunable_long *d = (struct tunable_long *)data;
  592 
  593         TUNABLE_LONG_FETCH(d->path, d->var);
  594 }
  595 
  596 void
  597 tunable_ulong_init(void *data)
  598 {
  599         struct tunable_ulong *d = (struct tunable_ulong *)data;
  600 
  601         TUNABLE_ULONG_FETCH(d->path, d->var);
  602 }
  603 
  604 void
  605 tunable_quad_init(void *data)
  606 {
  607         struct tunable_quad *d = (struct tunable_quad *)data;
  608 
  609         TUNABLE_QUAD_FETCH(d->path, d->var);
  610 }
  611 
  612 void
  613 tunable_str_init(void *data)
  614 {
  615         struct tunable_str *d = (struct tunable_str *)data;
  616 
  617         TUNABLE_STR_FETCH(d->path, d->var, d->size);
  618 }
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_environment.c

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