The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Mike Karels at Berkeley Software Design, Inc.
    7  *
    8  * Quite extensively rewritten by Poul-Henning Kamp of the FreeBSD
    9  * project, to make these variables more userfriendly.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  * 4. Neither the name of the University nor the names of its contributors
   20  *    may be used to endorse or promote products derived from this software
   21  *    without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   33  * SUCH DAMAGE.
   34  *
   35  *      @(#)kern_sysctl.c       8.4 (Berkeley) 4/14/94
   36  */
   37 
   38 #include <sys/cdefs.h>
   39 __FBSDID("$FreeBSD: releng/11.2/sys/kern/kern_sysctl.c 331722 2018-03-29 02:50:57Z eadler $");
   40 
   41 #include "opt_capsicum.h"
   42 #include "opt_compat.h"
   43 #include "opt_ktrace.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/fail.h>
   47 #include <sys/systm.h>
   48 #include <sys/capsicum.h>
   49 #include <sys/kernel.h>
   50 #include <sys/sysctl.h>
   51 #include <sys/malloc.h>
   52 #include <sys/priv.h>
   53 #include <sys/proc.h>
   54 #include <sys/jail.h>
   55 #include <sys/lock.h>
   56 #include <sys/mutex.h>
   57 #include <sys/rmlock.h>
   58 #include <sys/sbuf.h>
   59 #include <sys/sx.h>
   60 #include <sys/sysproto.h>
   61 #include <sys/uio.h>
   62 #ifdef KTRACE
   63 #include <sys/ktrace.h>
   64 #endif
   65 
   66 #include <net/vnet.h>
   67 
   68 #include <security/mac/mac_framework.h>
   69 
   70 #include <vm/vm.h>
   71 #include <vm/vm_extern.h>
   72 
   73 static MALLOC_DEFINE(M_SYSCTL, "sysctl", "sysctl internal magic");
   74 static MALLOC_DEFINE(M_SYSCTLOID, "sysctloid", "sysctl dynamic oids");
   75 static MALLOC_DEFINE(M_SYSCTLTMP, "sysctltmp", "sysctl temp output buffer");
   76 
   77 /*
   78  * The sysctllock protects the MIB tree.  It also protects sysctl
   79  * contexts used with dynamic sysctls.  The sysctl_register_oid() and
   80  * sysctl_unregister_oid() routines require the sysctllock to already
   81  * be held, so the sysctl_wlock() and sysctl_wunlock() routines are
   82  * provided for the few places in the kernel which need to use that
   83  * API rather than using the dynamic API.  Use of the dynamic API is
   84  * strongly encouraged for most code.
   85  *
   86  * The sysctlmemlock is used to limit the amount of user memory wired for
   87  * sysctl requests.  This is implemented by serializing any userland
   88  * sysctl requests larger than a single page via an exclusive lock.
   89  */
   90 static struct rmlock sysctllock;
   91 static struct sx __exclusive_cache_line sysctlmemlock;
   92 
   93 #define SYSCTL_WLOCK()          rm_wlock(&sysctllock)
   94 #define SYSCTL_WUNLOCK()        rm_wunlock(&sysctllock)
   95 #define SYSCTL_RLOCK(tracker)   rm_rlock(&sysctllock, (tracker))
   96 #define SYSCTL_RUNLOCK(tracker) rm_runlock(&sysctllock, (tracker))
   97 #define SYSCTL_WLOCKED()        rm_wowned(&sysctllock)
   98 #define SYSCTL_ASSERT_LOCKED()  rm_assert(&sysctllock, RA_LOCKED)
   99 #define SYSCTL_ASSERT_WLOCKED() rm_assert(&sysctllock, RA_WLOCKED)
  100 #define SYSCTL_ASSERT_RLOCKED() rm_assert(&sysctllock, RA_RLOCKED)
  101 #define SYSCTL_INIT()           rm_init_flags(&sysctllock, "sysctl lock", \
  102                                     RM_SLEEPABLE)
  103 #define SYSCTL_SLEEP(ch, wmesg, timo)                                   \
  104                                 rm_sleep(ch, &sysctllock, 0, wmesg, timo)
  105 
  106 static int sysctl_root(SYSCTL_HANDLER_ARGS);
  107 
  108 /* Root list */
  109 struct sysctl_oid_list sysctl__children = SLIST_HEAD_INITIALIZER(&sysctl__children);
  110 
  111 static int      sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
  112                     int recurse);
  113 static int      sysctl_old_kernel(struct sysctl_req *, const void *, size_t);
  114 static int      sysctl_new_kernel(struct sysctl_req *, void *, size_t);
  115 
  116 static struct sysctl_oid *
  117 sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
  118 {
  119         struct sysctl_oid *oidp;
  120 
  121         SYSCTL_ASSERT_LOCKED();
  122         SLIST_FOREACH(oidp, list, oid_link) {
  123                 if (strcmp(oidp->oid_name, name) == 0) {
  124                         return (oidp);
  125                 }
  126         }
  127         return (NULL);
  128 }
  129 
  130 /*
  131  * Initialization of the MIB tree.
  132  *
  133  * Order by number in each list.
  134  */
  135 void
  136 sysctl_wlock(void)
  137 {
  138 
  139         SYSCTL_WLOCK();
  140 }
  141 
  142 void
  143 sysctl_wunlock(void)
  144 {
  145 
  146         SYSCTL_WUNLOCK();
  147 }
  148 
  149 static int
  150 sysctl_root_handler_locked(struct sysctl_oid *oid, void *arg1, intmax_t arg2,
  151     struct sysctl_req *req, struct rm_priotracker *tracker)
  152 {
  153         int error;
  154 
  155         if (oid->oid_kind & CTLFLAG_DYN)
  156                 atomic_add_int(&oid->oid_running, 1);
  157 
  158         if (tracker != NULL)
  159                 SYSCTL_RUNLOCK(tracker);
  160         else
  161                 SYSCTL_WUNLOCK();
  162 
  163         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
  164                 mtx_lock(&Giant);
  165         error = oid->oid_handler(oid, arg1, arg2, req);
  166         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
  167                 mtx_unlock(&Giant);
  168 
  169         KFAIL_POINT_ERROR(_debug_fail_point, sysctl_running, error);
  170 
  171         if (tracker != NULL)
  172                 SYSCTL_RLOCK(tracker);
  173         else
  174                 SYSCTL_WLOCK();
  175 
  176         if (oid->oid_kind & CTLFLAG_DYN) {
  177                 if (atomic_fetchadd_int(&oid->oid_running, -1) == 1 &&
  178                     (oid->oid_kind & CTLFLAG_DYING) != 0)
  179                         wakeup(&oid->oid_running);
  180         }
  181 
  182         return (error);
  183 }
  184 
  185 static void
  186 sysctl_load_tunable_by_oid_locked(struct sysctl_oid *oidp)
  187 {
  188         struct sysctl_req req;
  189         struct sysctl_oid *curr;
  190         char *penv = NULL;
  191         char path[96];
  192         ssize_t rem = sizeof(path);
  193         ssize_t len;
  194         uint8_t val_8;
  195         uint16_t val_16;
  196         uint32_t val_32;
  197         int val_int;
  198         long val_long;
  199         int64_t val_64;
  200         quad_t val_quad;
  201         int error;
  202 
  203         path[--rem] = 0;
  204 
  205         for (curr = oidp; curr != NULL; curr = SYSCTL_PARENT(curr)) {
  206                 len = strlen(curr->oid_name);
  207                 rem -= len;
  208                 if (curr != oidp)
  209                         rem -= 1;
  210                 if (rem < 0) {
  211                         printf("OID path exceeds %d bytes\n", (int)sizeof(path));
  212                         return;
  213                 }
  214                 memcpy(path + rem, curr->oid_name, len);
  215                 if (curr != oidp)
  216                         path[rem + len] = '.';
  217         }
  218 
  219         memset(&req, 0, sizeof(req));
  220 
  221         req.td = curthread;
  222         req.oldfunc = sysctl_old_kernel;
  223         req.newfunc = sysctl_new_kernel;
  224         req.lock = REQ_UNWIRED;
  225 
  226         switch (oidp->oid_kind & CTLTYPE) {
  227         case CTLTYPE_INT:
  228                 if (getenv_int(path + rem, &val_int) == 0)
  229                         return;
  230                 req.newlen = sizeof(val_int);
  231                 req.newptr = &val_int;
  232                 break;
  233         case CTLTYPE_UINT:
  234                 if (getenv_uint(path + rem, (unsigned int *)&val_int) == 0)
  235                         return;
  236                 req.newlen = sizeof(val_int);
  237                 req.newptr = &val_int;
  238                 break;
  239         case CTLTYPE_LONG:
  240                 if (getenv_long(path + rem, &val_long) == 0)
  241                         return;
  242                 req.newlen = sizeof(val_long);
  243                 req.newptr = &val_long;
  244                 break;
  245         case CTLTYPE_ULONG:
  246                 if (getenv_ulong(path + rem, (unsigned long *)&val_long) == 0)
  247                         return;
  248                 req.newlen = sizeof(val_long);
  249                 req.newptr = &val_long;
  250                 break;
  251         case CTLTYPE_S8:
  252                 if (getenv_int(path + rem, &val_int) == 0)
  253                         return;
  254                 val_8 = val_int;
  255                 req.newlen = sizeof(val_8);
  256                 req.newptr = &val_8;
  257                 break;
  258         case CTLTYPE_S16:
  259                 if (getenv_int(path + rem, &val_int) == 0)
  260                         return;
  261                 val_16 = val_int;
  262                 req.newlen = sizeof(val_16);
  263                 req.newptr = &val_16;
  264                 break;
  265         case CTLTYPE_S32:
  266                 if (getenv_long(path + rem, &val_long) == 0)
  267                         return;
  268                 val_32 = val_long;
  269                 req.newlen = sizeof(val_32);
  270                 req.newptr = &val_32;
  271                 break;
  272         case CTLTYPE_S64:
  273                 if (getenv_quad(path + rem, &val_quad) == 0)
  274                         return;
  275                 val_64 = val_quad;
  276                 req.newlen = sizeof(val_64);
  277                 req.newptr = &val_64;
  278                 break;
  279         case CTLTYPE_U8:
  280                 if (getenv_uint(path + rem, (unsigned int *)&val_int) == 0)
  281                         return;
  282                 val_8 = val_int;
  283                 req.newlen = sizeof(val_8);
  284                 req.newptr = &val_8;
  285                 break;
  286         case CTLTYPE_U16:
  287                 if (getenv_uint(path + rem, (unsigned int *)&val_int) == 0)
  288                         return;
  289                 val_16 = val_int;
  290                 req.newlen = sizeof(val_16);
  291                 req.newptr = &val_16;
  292                 break;
  293         case CTLTYPE_U32:
  294                 if (getenv_ulong(path + rem, (unsigned long *)&val_long) == 0)
  295                         return;
  296                 val_32 = val_long;
  297                 req.newlen = sizeof(val_32);
  298                 req.newptr = &val_32;
  299                 break;
  300         case CTLTYPE_U64:
  301                 /* XXX there is no getenv_uquad() */
  302                 if (getenv_quad(path + rem, &val_quad) == 0)
  303                         return;
  304                 val_64 = val_quad;
  305                 req.newlen = sizeof(val_64);
  306                 req.newptr = &val_64;
  307                 break;
  308         case CTLTYPE_STRING:
  309                 penv = kern_getenv(path + rem);
  310                 if (penv == NULL)
  311                         return;
  312                 req.newlen = strlen(penv);
  313                 req.newptr = penv;
  314                 break;
  315         default:
  316                 return;
  317         }
  318         error = sysctl_root_handler_locked(oidp, oidp->oid_arg1,
  319             oidp->oid_arg2, &req, NULL);
  320         if (error != 0)
  321                 printf("Setting sysctl %s failed: %d\n", path + rem, error);
  322         if (penv != NULL)
  323                 freeenv(penv);
  324 }
  325 
  326 void
  327 sysctl_register_oid(struct sysctl_oid *oidp)
  328 {
  329         struct sysctl_oid_list *parent = oidp->oid_parent;
  330         struct sysctl_oid *p;
  331         struct sysctl_oid *q;
  332         int oid_number;
  333         int timeout = 2;
  334 
  335         /*
  336          * First check if another oid with the same name already
  337          * exists in the parent's list.
  338          */
  339         SYSCTL_ASSERT_WLOCKED();
  340         p = sysctl_find_oidname(oidp->oid_name, parent);
  341         if (p != NULL) {
  342                 if ((p->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  343                         p->oid_refcnt++;
  344                         return;
  345                 } else {
  346                         printf("can't re-use a leaf (%s)!\n", p->oid_name);
  347                         return;
  348                 }
  349         }
  350         /* get current OID number */
  351         oid_number = oidp->oid_number;
  352 
  353 #if (OID_AUTO >= 0)
  354 #error "OID_AUTO is expected to be a negative value"
  355 #endif  
  356         /*
  357          * Any negative OID number qualifies as OID_AUTO. Valid OID
  358          * numbers should always be positive.
  359          *
  360          * NOTE: DO NOT change the starting value here, change it in
  361          * <sys/sysctl.h>, and make sure it is at least 256 to
  362          * accommodate e.g. net.inet.raw as a static sysctl node.
  363          */
  364         if (oid_number < 0) {
  365                 static int newoid;
  366 
  367                 /*
  368                  * By decrementing the next OID number we spend less
  369                  * time inserting the OIDs into a sorted list.
  370                  */
  371                 if (--newoid < CTL_AUTO_START)
  372                         newoid = 0x7fffffff;
  373 
  374                 oid_number = newoid;
  375         }
  376 
  377         /*
  378          * Insert the OID into the parent's list sorted by OID number.
  379          */
  380 retry:
  381         q = NULL;
  382         SLIST_FOREACH(p, parent, oid_link) {
  383                 /* check if the current OID number is in use */
  384                 if (oid_number == p->oid_number) {
  385                         /* get the next valid OID number */
  386                         if (oid_number < CTL_AUTO_START ||
  387                             oid_number == 0x7fffffff) {
  388                                 /* wraparound - restart */
  389                                 oid_number = CTL_AUTO_START;
  390                                 /* don't loop forever */
  391                                 if (!timeout--)
  392                                         panic("sysctl: Out of OID numbers\n");
  393                                 goto retry;
  394                         } else {
  395                                 oid_number++;
  396                         }
  397                 } else if (oid_number < p->oid_number)
  398                         break;
  399                 q = p;
  400         }
  401         /* check for non-auto OID number collision */
  402         if (oidp->oid_number >= 0 && oidp->oid_number < CTL_AUTO_START &&
  403             oid_number >= CTL_AUTO_START) {
  404                 printf("sysctl: OID number(%d) is already in use for '%s'\n",
  405                     oidp->oid_number, oidp->oid_name);
  406         }
  407         /* update the OID number, if any */
  408         oidp->oid_number = oid_number;
  409         if (q != NULL)
  410                 SLIST_INSERT_AFTER(q, oidp, oid_link);
  411         else
  412                 SLIST_INSERT_HEAD(parent, oidp, oid_link);
  413 
  414         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE &&
  415 #ifdef VIMAGE
  416             (oidp->oid_kind & CTLFLAG_VNET) == 0 &&
  417 #endif
  418             (oidp->oid_kind & CTLFLAG_TUN) != 0 &&
  419             (oidp->oid_kind & CTLFLAG_NOFETCH) == 0) {
  420                 /* only fetch value once */
  421                 oidp->oid_kind |= CTLFLAG_NOFETCH;
  422                 /* try to fetch value from kernel environment */
  423                 sysctl_load_tunable_by_oid_locked(oidp);
  424         }
  425 }
  426 
  427 void
  428 sysctl_register_disabled_oid(struct sysctl_oid *oidp)
  429 {
  430 
  431         /*
  432          * Mark the leaf as dormant if it's not to be immediately enabled.
  433          * We do not disable nodes as they can be shared between modules
  434          * and it is always safe to access a node.
  435          */
  436         KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
  437             ("internal flag is set in oid_kind"));
  438         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  439                 oidp->oid_kind |= CTLFLAG_DORMANT;
  440         sysctl_register_oid(oidp);
  441 }
  442 
  443 void
  444 sysctl_enable_oid(struct sysctl_oid *oidp)
  445 {
  446 
  447         SYSCTL_ASSERT_WLOCKED();
  448         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  449                 KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
  450                     ("sysctl node is marked as dormant"));
  451                 return;
  452         }
  453         KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) != 0,
  454             ("enabling already enabled sysctl oid"));
  455         oidp->oid_kind &= ~CTLFLAG_DORMANT;
  456 }
  457 
  458 void
  459 sysctl_unregister_oid(struct sysctl_oid *oidp)
  460 {
  461         struct sysctl_oid *p;
  462         int error;
  463 
  464         SYSCTL_ASSERT_WLOCKED();
  465         error = ENOENT;
  466         if (oidp->oid_number == OID_AUTO) {
  467                 error = EINVAL;
  468         } else {
  469                 SLIST_FOREACH(p, oidp->oid_parent, oid_link) {
  470                         if (p == oidp) {
  471                                 SLIST_REMOVE(oidp->oid_parent, oidp,
  472                                     sysctl_oid, oid_link);
  473                                 error = 0;
  474                                 break;
  475                         }
  476                 }
  477         }
  478 
  479         /* 
  480          * This can happen when a module fails to register and is
  481          * being unloaded afterwards.  It should not be a panic()
  482          * for normal use.
  483          */
  484         if (error)
  485                 printf("%s: failed to unregister sysctl\n", __func__);
  486 }
  487 
  488 /* Initialize a new context to keep track of dynamically added sysctls. */
  489 int
  490 sysctl_ctx_init(struct sysctl_ctx_list *c)
  491 {
  492 
  493         if (c == NULL) {
  494                 return (EINVAL);
  495         }
  496 
  497         /*
  498          * No locking here, the caller is responsible for not adding
  499          * new nodes to a context until after this function has
  500          * returned.
  501          */
  502         TAILQ_INIT(c);
  503         return (0);
  504 }
  505 
  506 /* Free the context, and destroy all dynamic oids registered in this context */
  507 int
  508 sysctl_ctx_free(struct sysctl_ctx_list *clist)
  509 {
  510         struct sysctl_ctx_entry *e, *e1;
  511         int error;
  512 
  513         error = 0;
  514         /*
  515          * First perform a "dry run" to check if it's ok to remove oids.
  516          * XXX FIXME
  517          * XXX This algorithm is a hack. But I don't know any
  518          * XXX better solution for now...
  519          */
  520         SYSCTL_WLOCK();
  521         TAILQ_FOREACH(e, clist, link) {
  522                 error = sysctl_remove_oid_locked(e->entry, 0, 0);
  523                 if (error)
  524                         break;
  525         }
  526         /*
  527          * Restore deregistered entries, either from the end,
  528          * or from the place where error occurred.
  529          * e contains the entry that was not unregistered
  530          */
  531         if (error)
  532                 e1 = TAILQ_PREV(e, sysctl_ctx_list, link);
  533         else
  534                 e1 = TAILQ_LAST(clist, sysctl_ctx_list);
  535         while (e1 != NULL) {
  536                 sysctl_register_oid(e1->entry);
  537                 e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
  538         }
  539         if (error) {
  540                 SYSCTL_WUNLOCK();
  541                 return(EBUSY);
  542         }
  543         /* Now really delete the entries */
  544         e = TAILQ_FIRST(clist);
  545         while (e != NULL) {
  546                 e1 = TAILQ_NEXT(e, link);
  547                 error = sysctl_remove_oid_locked(e->entry, 1, 0);
  548                 if (error)
  549                         panic("sysctl_remove_oid: corrupt tree, entry: %s",
  550                             e->entry->oid_name);
  551                 free(e, M_SYSCTLOID);
  552                 e = e1;
  553         }
  554         SYSCTL_WUNLOCK();
  555         return (error);
  556 }
  557 
  558 /* Add an entry to the context */
  559 struct sysctl_ctx_entry *
  560 sysctl_ctx_entry_add(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  561 {
  562         struct sysctl_ctx_entry *e;
  563 
  564         SYSCTL_ASSERT_WLOCKED();
  565         if (clist == NULL || oidp == NULL)
  566                 return(NULL);
  567         e = malloc(sizeof(struct sysctl_ctx_entry), M_SYSCTLOID, M_WAITOK);
  568         e->entry = oidp;
  569         TAILQ_INSERT_HEAD(clist, e, link);
  570         return (e);
  571 }
  572 
  573 /* Find an entry in the context */
  574 struct sysctl_ctx_entry *
  575 sysctl_ctx_entry_find(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  576 {
  577         struct sysctl_ctx_entry *e;
  578 
  579         SYSCTL_ASSERT_WLOCKED();
  580         if (clist == NULL || oidp == NULL)
  581                 return(NULL);
  582         TAILQ_FOREACH(e, clist, link) {
  583                 if(e->entry == oidp)
  584                         return(e);
  585         }
  586         return (e);
  587 }
  588 
  589 /*
  590  * Delete an entry from the context.
  591  * NOTE: this function doesn't free oidp! You have to remove it
  592  * with sysctl_remove_oid().
  593  */
  594 int
  595 sysctl_ctx_entry_del(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  596 {
  597         struct sysctl_ctx_entry *e;
  598 
  599         if (clist == NULL || oidp == NULL)
  600                 return (EINVAL);
  601         SYSCTL_WLOCK();
  602         e = sysctl_ctx_entry_find(clist, oidp);
  603         if (e != NULL) {
  604                 TAILQ_REMOVE(clist, e, link);
  605                 SYSCTL_WUNLOCK();
  606                 free(e, M_SYSCTLOID);
  607                 return (0);
  608         } else {
  609                 SYSCTL_WUNLOCK();
  610                 return (ENOENT);
  611         }
  612 }
  613 
  614 /*
  615  * Remove dynamically created sysctl trees.
  616  * oidp - top of the tree to be removed
  617  * del - if 0 - just deregister, otherwise free up entries as well
  618  * recurse - if != 0 traverse the subtree to be deleted
  619  */
  620 int
  621 sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse)
  622 {
  623         int error;
  624 
  625         SYSCTL_WLOCK();
  626         error = sysctl_remove_oid_locked(oidp, del, recurse);
  627         SYSCTL_WUNLOCK();
  628         return (error);
  629 }
  630 
  631 int
  632 sysctl_remove_name(struct sysctl_oid *parent, const char *name,
  633     int del, int recurse)
  634 {
  635         struct sysctl_oid *p, *tmp;
  636         int error;
  637 
  638         error = ENOENT;
  639         SYSCTL_WLOCK();
  640         SLIST_FOREACH_SAFE(p, SYSCTL_CHILDREN(parent), oid_link, tmp) {
  641                 if (strcmp(p->oid_name, name) == 0) {
  642                         error = sysctl_remove_oid_locked(p, del, recurse);
  643                         break;
  644                 }
  645         }
  646         SYSCTL_WUNLOCK();
  647 
  648         return (error);
  649 }
  650 
  651 
  652 static int
  653 sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
  654 {
  655         struct sysctl_oid *p, *tmp;
  656         int error;
  657 
  658         SYSCTL_ASSERT_WLOCKED();
  659         if (oidp == NULL)
  660                 return(EINVAL);
  661         if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
  662                 printf("Warning: can't remove non-dynamic nodes (%s)!\n",
  663                     oidp->oid_name);
  664                 return (EINVAL);
  665         }
  666         /*
  667          * WARNING: normal method to do this should be through
  668          * sysctl_ctx_free(). Use recursing as the last resort
  669          * method to purge your sysctl tree of leftovers...
  670          * However, if some other code still references these nodes,
  671          * it will panic.
  672          */
  673         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  674                 if (oidp->oid_refcnt == 1) {
  675                         SLIST_FOREACH_SAFE(p,
  676                             SYSCTL_CHILDREN(oidp), oid_link, tmp) {
  677                                 if (!recurse) {
  678                                         printf("Warning: failed attempt to "
  679                                             "remove oid %s with child %s\n",
  680                                             oidp->oid_name, p->oid_name);
  681                                         return (ENOTEMPTY);
  682                                 }
  683                                 error = sysctl_remove_oid_locked(p, del,
  684                                     recurse);
  685                                 if (error)
  686                                         return (error);
  687                         }
  688                 }
  689         }
  690         if (oidp->oid_refcnt > 1 ) {
  691                 oidp->oid_refcnt--;
  692         } else {
  693                 if (oidp->oid_refcnt == 0) {
  694                         printf("Warning: bad oid_refcnt=%u (%s)!\n",
  695                                 oidp->oid_refcnt, oidp->oid_name);
  696                         return (EINVAL);
  697                 }
  698                 sysctl_unregister_oid(oidp);
  699                 if (del) {
  700                         /*
  701                          * Wait for all threads running the handler to drain.
  702                          * This preserves the previous behavior when the
  703                          * sysctl lock was held across a handler invocation,
  704                          * and is necessary for module unload correctness.
  705                          */
  706                         while (oidp->oid_running > 0) {
  707                                 oidp->oid_kind |= CTLFLAG_DYING;
  708                                 SYSCTL_SLEEP(&oidp->oid_running, "oidrm", 0);
  709                         }
  710                         if (oidp->oid_descr)
  711                                 free(__DECONST(char *, oidp->oid_descr),
  712                                     M_SYSCTLOID);
  713                         free(__DECONST(char *, oidp->oid_name), M_SYSCTLOID);
  714                         free(oidp, M_SYSCTLOID);
  715                 }
  716         }
  717         return (0);
  718 }
  719 /*
  720  * Create new sysctls at run time.
  721  * clist may point to a valid context initialized with sysctl_ctx_init().
  722  */
  723 struct sysctl_oid *
  724 sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
  725         int number, const char *name, int kind, void *arg1, intmax_t arg2,
  726         int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr)
  727 {
  728         struct sysctl_oid *oidp;
  729 
  730         /* You have to hook up somewhere.. */
  731         if (parent == NULL)
  732                 return(NULL);
  733         /* Check if the node already exists, otherwise create it */
  734         SYSCTL_WLOCK();
  735         oidp = sysctl_find_oidname(name, parent);
  736         if (oidp != NULL) {
  737                 if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  738                         oidp->oid_refcnt++;
  739                         /* Update the context */
  740                         if (clist != NULL)
  741                                 sysctl_ctx_entry_add(clist, oidp);
  742                         SYSCTL_WUNLOCK();
  743                         return (oidp);
  744                 } else {
  745                         SYSCTL_WUNLOCK();
  746                         printf("can't re-use a leaf (%s)!\n", name);
  747                         return (NULL);
  748                 }
  749         }
  750         oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
  751         oidp->oid_parent = parent;
  752         SLIST_INIT(&oidp->oid_children);
  753         oidp->oid_number = number;
  754         oidp->oid_refcnt = 1;
  755         oidp->oid_name = strdup(name, M_SYSCTLOID);
  756         oidp->oid_handler = handler;
  757         oidp->oid_kind = CTLFLAG_DYN | kind;
  758         oidp->oid_arg1 = arg1;
  759         oidp->oid_arg2 = arg2;
  760         oidp->oid_fmt = fmt;
  761         if (descr != NULL)
  762                 oidp->oid_descr = strdup(descr, M_SYSCTLOID);
  763         /* Update the context, if used */
  764         if (clist != NULL)
  765                 sysctl_ctx_entry_add(clist, oidp);
  766         /* Register this oid */
  767         sysctl_register_oid(oidp);
  768         SYSCTL_WUNLOCK();
  769         return (oidp);
  770 }
  771 
  772 /*
  773  * Rename an existing oid.
  774  */
  775 void
  776 sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
  777 {
  778         char *newname;
  779         char *oldname;
  780 
  781         newname = strdup(name, M_SYSCTLOID);
  782         SYSCTL_WLOCK();
  783         oldname = __DECONST(char *, oidp->oid_name);
  784         oidp->oid_name = newname;
  785         SYSCTL_WUNLOCK();
  786         free(oldname, M_SYSCTLOID);
  787 }
  788 
  789 /*
  790  * Reparent an existing oid.
  791  */
  792 int
  793 sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
  794 {
  795         struct sysctl_oid *oidp;
  796 
  797         SYSCTL_WLOCK();
  798         if (oid->oid_parent == parent) {
  799                 SYSCTL_WUNLOCK();
  800                 return (0);
  801         }
  802         oidp = sysctl_find_oidname(oid->oid_name, parent);
  803         if (oidp != NULL) {
  804                 SYSCTL_WUNLOCK();
  805                 return (EEXIST);
  806         }
  807         sysctl_unregister_oid(oid);
  808         oid->oid_parent = parent;
  809         oid->oid_number = OID_AUTO;
  810         sysctl_register_oid(oid);
  811         SYSCTL_WUNLOCK();
  812         return (0);
  813 }
  814 
  815 /*
  816  * Register the kernel's oids on startup.
  817  */
  818 SET_DECLARE(sysctl_set, struct sysctl_oid);
  819 
  820 static void
  821 sysctl_register_all(void *arg)
  822 {
  823         struct sysctl_oid **oidp;
  824 
  825         sx_init(&sysctlmemlock, "sysctl mem");
  826         SYSCTL_INIT();
  827         SYSCTL_WLOCK();
  828         SET_FOREACH(oidp, sysctl_set)
  829                 sysctl_register_oid(*oidp);
  830         SYSCTL_WUNLOCK();
  831 }
  832 SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, 0);
  833 
  834 /*
  835  * "Staff-functions"
  836  *
  837  * These functions implement a presently undocumented interface 
  838  * used by the sysctl program to walk the tree, and get the type
  839  * so it can print the value.
  840  * This interface is under work and consideration, and should probably
  841  * be killed with a big axe by the first person who can find the time.
  842  * (be aware though, that the proper interface isn't as obvious as it
  843  * may seem, there are various conflicting requirements.
  844  *
  845  * {0,0}        printf the entire MIB-tree.
  846  * {0,1,...}    return the name of the "..." OID.
  847  * {0,2,...}    return the next OID.
  848  * {0,3}        return the OID of the name in "new"
  849  * {0,4,...}    return the kind & format info for the "..." OID.
  850  * {0,5,...}    return the description the "..." OID.
  851  */
  852 
  853 #ifdef SYSCTL_DEBUG
  854 static void
  855 sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
  856 {
  857         int k;
  858         struct sysctl_oid *oidp;
  859 
  860         SYSCTL_ASSERT_LOCKED();
  861         SLIST_FOREACH(oidp, l, oid_link) {
  862 
  863                 for (k=0; k<i; k++)
  864                         printf(" ");
  865 
  866                 printf("%d %s ", oidp->oid_number, oidp->oid_name);
  867 
  868                 printf("%c%c",
  869                         oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
  870                         oidp->oid_kind & CTLFLAG_WR ? 'W':' ');
  871 
  872                 if (oidp->oid_handler)
  873                         printf(" *Handler");
  874 
  875                 switch (oidp->oid_kind & CTLTYPE) {
  876                         case CTLTYPE_NODE:
  877                                 printf(" Node\n");
  878                                 if (!oidp->oid_handler) {
  879                                         sysctl_sysctl_debug_dump_node(
  880                                             SYSCTL_CHILDREN(oidp), i + 2);
  881                                 }
  882                                 break;
  883                         case CTLTYPE_INT:    printf(" Int\n"); break;
  884                         case CTLTYPE_UINT:   printf(" u_int\n"); break;
  885                         case CTLTYPE_LONG:   printf(" Long\n"); break;
  886                         case CTLTYPE_ULONG:  printf(" u_long\n"); break;
  887                         case CTLTYPE_STRING: printf(" String\n"); break;
  888                         case CTLTYPE_S8:     printf(" int8_t\n"); break;
  889                         case CTLTYPE_S16:    printf(" int16_t\n"); break;
  890                         case CTLTYPE_S32:    printf(" int32_t\n"); break;
  891                         case CTLTYPE_S64:    printf(" int64_t\n"); break;
  892                         case CTLTYPE_U8:     printf(" uint8_t\n"); break;
  893                         case CTLTYPE_U16:    printf(" uint16_t\n"); break;
  894                         case CTLTYPE_U32:    printf(" uint32_t\n"); break;
  895                         case CTLTYPE_U64:    printf(" uint64_t\n"); break;
  896                         case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
  897                         default:             printf("\n");
  898                 }
  899 
  900         }
  901 }
  902 
  903 static int
  904 sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
  905 {
  906         struct rm_priotracker tracker;
  907         int error;
  908 
  909         error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
  910         if (error)
  911                 return (error);
  912         SYSCTL_RLOCK(&tracker);
  913         sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
  914         SYSCTL_RUNLOCK(&tracker);
  915         return (ENOENT);
  916 }
  917 
  918 SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
  919         0, 0, sysctl_sysctl_debug, "-", "");
  920 #endif
  921 
  922 static int
  923 sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
  924 {
  925         int *name = (int *) arg1;
  926         u_int namelen = arg2;
  927         int error = 0;
  928         struct sysctl_oid *oid;
  929         struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
  930         struct rm_priotracker tracker;
  931         char buf[10];
  932 
  933         SYSCTL_RLOCK(&tracker);
  934         while (namelen) {
  935                 if (!lsp) {
  936                         snprintf(buf,sizeof(buf),"%d",*name);
  937                         if (req->oldidx)
  938                                 error = SYSCTL_OUT(req, ".", 1);
  939                         if (!error)
  940                                 error = SYSCTL_OUT(req, buf, strlen(buf));
  941                         if (error)
  942                                 goto out;
  943                         namelen--;
  944                         name++;
  945                         continue;
  946                 }
  947                 lsp2 = NULL;
  948                 SLIST_FOREACH(oid, lsp, oid_link) {
  949                         if (oid->oid_number != *name)
  950                                 continue;
  951 
  952                         if (req->oldidx)
  953                                 error = SYSCTL_OUT(req, ".", 1);
  954                         if (!error)
  955                                 error = SYSCTL_OUT(req, oid->oid_name,
  956                                         strlen(oid->oid_name));
  957                         if (error)
  958                                 goto out;
  959 
  960                         namelen--;
  961                         name++;
  962 
  963                         if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
  964                                 break;
  965 
  966                         if (oid->oid_handler)
  967                                 break;
  968 
  969                         lsp2 = SYSCTL_CHILDREN(oid);
  970                         break;
  971                 }
  972                 lsp = lsp2;
  973         }
  974         error = SYSCTL_OUT(req, "", 1);
  975  out:
  976         SYSCTL_RUNLOCK(&tracker);
  977         return (error);
  978 }
  979 
  980 /*
  981  * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
  982  * capability mode.
  983  */
  984 static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
  985     sysctl_sysctl_name, "");
  986 
  987 static int
  988 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
  989         int *next, int *len, int level, struct sysctl_oid **oidpp)
  990 {
  991         struct sysctl_oid *oidp;
  992 
  993         SYSCTL_ASSERT_LOCKED();
  994         *len = level;
  995         SLIST_FOREACH(oidp, lsp, oid_link) {
  996                 *next = oidp->oid_number;
  997                 *oidpp = oidp;
  998 
  999                 if ((oidp->oid_kind & (CTLFLAG_SKIP | CTLFLAG_DORMANT)) != 0)
 1000                         continue;
 1001 
 1002                 if (!namelen) {
 1003                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
 1004                                 return (0);
 1005                         if (oidp->oid_handler) 
 1006                                 /* We really should call the handler here...*/
 1007                                 return (0);
 1008                         lsp = SYSCTL_CHILDREN(oidp);
 1009                         if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1, 
 1010                                 len, level+1, oidpp))
 1011                                 return (0);
 1012                         goto emptynode;
 1013                 }
 1014 
 1015                 if (oidp->oid_number < *name)
 1016                         continue;
 1017 
 1018                 if (oidp->oid_number > *name) {
 1019                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 1020                                 return (0);
 1021                         if (oidp->oid_handler)
 1022                                 return (0);
 1023                         lsp = SYSCTL_CHILDREN(oidp);
 1024                         if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, 
 1025                                 next+1, len, level+1, oidpp))
 1026                                 return (0);
 1027                         goto next;
 1028                 }
 1029                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 1030                         continue;
 1031 
 1032                 if (oidp->oid_handler)
 1033                         continue;
 1034 
 1035                 lsp = SYSCTL_CHILDREN(oidp);
 1036                 if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1, 
 1037                         len, level+1, oidpp))
 1038                         return (0);
 1039         next:
 1040                 namelen = 1;
 1041         emptynode:
 1042                 *len = level;
 1043         }
 1044         return (1);
 1045 }
 1046 
 1047 static int
 1048 sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
 1049 {
 1050         int *name = (int *) arg1;
 1051         u_int namelen = arg2;
 1052         int i, j, error;
 1053         struct sysctl_oid *oid;
 1054         struct sysctl_oid_list *lsp = &sysctl__children;
 1055         struct rm_priotracker tracker;
 1056         int newoid[CTL_MAXNAME];
 1057 
 1058         SYSCTL_RLOCK(&tracker);
 1059         i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
 1060         SYSCTL_RUNLOCK(&tracker);
 1061         if (i)
 1062                 return (ENOENT);
 1063         error = SYSCTL_OUT(req, newoid, j * sizeof (int));
 1064         return (error);
 1065 }
 1066 
 1067 /*
 1068  * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
 1069  * capability mode.
 1070  */
 1071 static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
 1072     sysctl_sysctl_next, "");
 1073 
 1074 static int
 1075 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
 1076 {
 1077         struct sysctl_oid *oidp;
 1078         struct sysctl_oid_list *lsp = &sysctl__children;
 1079         char *p;
 1080 
 1081         SYSCTL_ASSERT_LOCKED();
 1082 
 1083         for (*len = 0; *len < CTL_MAXNAME;) {
 1084                 p = strsep(&name, ".");
 1085 
 1086                 oidp = SLIST_FIRST(lsp);
 1087                 for (;; oidp = SLIST_NEXT(oidp, oid_link)) {
 1088                         if (oidp == NULL)
 1089                                 return (ENOENT);
 1090                         if (strcmp(p, oidp->oid_name) == 0)
 1091                                 break;
 1092                 }
 1093                 *oid++ = oidp->oid_number;
 1094                 (*len)++;
 1095 
 1096                 if (name == NULL || *name == '\0') {
 1097                         if (oidpp)
 1098                                 *oidpp = oidp;
 1099                         return (0);
 1100                 }
 1101 
 1102                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 1103                         break;
 1104 
 1105                 if (oidp->oid_handler)
 1106                         break;
 1107 
 1108                 lsp = SYSCTL_CHILDREN(oidp);
 1109         }
 1110         return (ENOENT);
 1111 }
 1112 
 1113 static int
 1114 sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
 1115 {
 1116         char *p;
 1117         int error, oid[CTL_MAXNAME], len = 0;
 1118         struct sysctl_oid *op = NULL;
 1119         struct rm_priotracker tracker;
 1120         char buf[32];
 1121 
 1122         if (!req->newlen) 
 1123                 return (ENOENT);
 1124         if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
 1125                 return (ENAMETOOLONG);
 1126 
 1127         p = buf;
 1128         if (req->newlen >= sizeof(buf))
 1129                 p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
 1130 
 1131         error = SYSCTL_IN(req, p, req->newlen);
 1132         if (error) {
 1133                 if (p != buf)
 1134                         free(p, M_SYSCTL);
 1135                 return (error);
 1136         }
 1137 
 1138         p [req->newlen] = '\0';
 1139 
 1140         SYSCTL_RLOCK(&tracker);
 1141         error = name2oid(p, oid, &len, &op);
 1142         SYSCTL_RUNLOCK(&tracker);
 1143 
 1144         if (p != buf)
 1145                 free(p, M_SYSCTL);
 1146 
 1147         if (error)
 1148                 return (error);
 1149 
 1150         error = SYSCTL_OUT(req, oid, len * sizeof *oid);
 1151         return (error);
 1152 }
 1153 
 1154 /*
 1155  * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
 1156  * capability mode.
 1157  */
 1158 SYSCTL_PROC(_sysctl, 3, name2oid,
 1159     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE
 1160     | CTLFLAG_CAPRW, 0, 0, sysctl_sysctl_name2oid, "I", "");
 1161 
 1162 static int
 1163 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
 1164 {
 1165         struct sysctl_oid *oid;
 1166         struct rm_priotracker tracker;
 1167         int error;
 1168 
 1169         SYSCTL_RLOCK(&tracker);
 1170         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
 1171         if (error)
 1172                 goto out;
 1173 
 1174         if (oid->oid_fmt == NULL) {
 1175                 error = ENOENT;
 1176                 goto out;
 1177         }
 1178         error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
 1179         if (error)
 1180                 goto out;
 1181         error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
 1182  out:
 1183         SYSCTL_RUNLOCK(&tracker);
 1184         return (error);
 1185 }
 1186 
 1187 
 1188 static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
 1189     sysctl_sysctl_oidfmt, "");
 1190 
 1191 static int
 1192 sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
 1193 {
 1194         struct sysctl_oid *oid;
 1195         struct rm_priotracker tracker;
 1196         int error;
 1197 
 1198         SYSCTL_RLOCK(&tracker);
 1199         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
 1200         if (error)
 1201                 goto out;
 1202 
 1203         if (oid->oid_descr == NULL) {
 1204                 error = ENOENT;
 1205                 goto out;
 1206         }
 1207         error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
 1208  out:
 1209         SYSCTL_RUNLOCK(&tracker);
 1210         return (error);
 1211 }
 1212 
 1213 static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
 1214     sysctl_sysctl_oiddescr, "");
 1215 
 1216 /*
 1217  * Default "handler" functions.
 1218  */
 1219 
 1220 /*
 1221  * Handle a bool.
 1222  * Two cases:
 1223  *     a variable:  point arg1 at it.
 1224  *     a constant:  pass it in arg2.
 1225  */
 1226 
 1227 int
 1228 sysctl_handle_bool(SYSCTL_HANDLER_ARGS)
 1229 {
 1230         uint8_t temp;
 1231         int error;
 1232 
 1233         /*
 1234          * Attempt to get a coherent snapshot by making a copy of the data.
 1235          */
 1236         if (arg1)
 1237                 temp = *(bool *)arg1 ? 1 : 0;
 1238         else
 1239                 temp = arg2 ? 1 : 0;
 1240 
 1241         error = SYSCTL_OUT(req, &temp, sizeof(temp));
 1242         if (error || !req->newptr)
 1243                 return (error);
 1244 
 1245         if (!arg1)
 1246                 error = EPERM;
 1247         else {
 1248                 error = SYSCTL_IN(req, &temp, sizeof(temp));
 1249                 if (!error)
 1250                         *(bool *)arg1 = temp ? 1 : 0;
 1251         }
 1252         return (error);
 1253 }
 1254 
 1255 /*
 1256  * Handle an int8_t, signed or unsigned.
 1257  * Two cases:
 1258  *     a variable:  point arg1 at it.
 1259  *     a constant:  pass it in arg2.
 1260  */
 1261 
 1262 int
 1263 sysctl_handle_8(SYSCTL_HANDLER_ARGS)
 1264 {
 1265         int8_t tmpout;
 1266         int error = 0;
 1267 
 1268         /*
 1269          * Attempt to get a coherent snapshot by making a copy of the data.
 1270          */
 1271         if (arg1)
 1272                 tmpout = *(int8_t *)arg1;
 1273         else
 1274                 tmpout = arg2;
 1275         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
 1276 
 1277         if (error || !req->newptr)
 1278                 return (error);
 1279 
 1280         if (!arg1)
 1281                 error = EPERM;
 1282         else
 1283                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
 1284         return (error);
 1285 }
 1286 
 1287 /*
 1288  * Handle an int16_t, signed or unsigned.
 1289  * Two cases:
 1290  *     a variable:  point arg1 at it.
 1291  *     a constant:  pass it in arg2.
 1292  */
 1293 
 1294 int
 1295 sysctl_handle_16(SYSCTL_HANDLER_ARGS)
 1296 {
 1297         int16_t tmpout;
 1298         int error = 0;
 1299 
 1300         /*
 1301          * Attempt to get a coherent snapshot by making a copy of the data.
 1302          */
 1303         if (arg1)
 1304                 tmpout = *(int16_t *)arg1;
 1305         else
 1306                 tmpout = arg2;
 1307         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
 1308 
 1309         if (error || !req->newptr)
 1310                 return (error);
 1311 
 1312         if (!arg1)
 1313                 error = EPERM;
 1314         else
 1315                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
 1316         return (error);
 1317 }
 1318 
 1319 /*
 1320  * Handle an int32_t, signed or unsigned.
 1321  * Two cases:
 1322  *     a variable:  point arg1 at it.
 1323  *     a constant:  pass it in arg2.
 1324  */
 1325 
 1326 int
 1327 sysctl_handle_32(SYSCTL_HANDLER_ARGS)
 1328 {
 1329         int32_t tmpout;
 1330         int error = 0;
 1331 
 1332         /*
 1333          * Attempt to get a coherent snapshot by making a copy of the data.
 1334          */
 1335         if (arg1)
 1336                 tmpout = *(int32_t *)arg1;
 1337         else
 1338                 tmpout = arg2;
 1339         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
 1340 
 1341         if (error || !req->newptr)
 1342                 return (error);
 1343 
 1344         if (!arg1)
 1345                 error = EPERM;
 1346         else
 1347                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
 1348         return (error);
 1349 }
 1350 
 1351 /*
 1352  * Handle an int, signed or unsigned.
 1353  * Two cases:
 1354  *     a variable:  point arg1 at it.
 1355  *     a constant:  pass it in arg2.
 1356  */
 1357 
 1358 int
 1359 sysctl_handle_int(SYSCTL_HANDLER_ARGS)
 1360 {
 1361         int tmpout, error = 0;
 1362 
 1363         /*
 1364          * Attempt to get a coherent snapshot by making a copy of the data.
 1365          */
 1366         if (arg1)
 1367                 tmpout = *(int *)arg1;
 1368         else
 1369                 tmpout = arg2;
 1370         error = SYSCTL_OUT(req, &tmpout, sizeof(int));
 1371 
 1372         if (error || !req->newptr)
 1373                 return (error);
 1374 
 1375         if (!arg1)
 1376                 error = EPERM;
 1377         else
 1378                 error = SYSCTL_IN(req, arg1, sizeof(int));
 1379         return (error);
 1380 }
 1381 
 1382 /*
 1383  * Based on on sysctl_handle_int() convert milliseconds into ticks.
 1384  * Note: this is used by TCP.
 1385  */
 1386 
 1387 int
 1388 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
 1389 {
 1390         int error, s, tt;
 1391 
 1392         tt = *(int *)arg1;
 1393         s = (int)((int64_t)tt * 1000 / hz);
 1394 
 1395         error = sysctl_handle_int(oidp, &s, 0, req);
 1396         if (error || !req->newptr)
 1397                 return (error);
 1398 
 1399         tt = (int)((int64_t)s * hz / 1000);
 1400         if (tt < 1)
 1401                 return (EINVAL);
 1402 
 1403         *(int *)arg1 = tt;
 1404         return (0);
 1405 }
 1406 
 1407 
 1408 /*
 1409  * Handle a long, signed or unsigned.
 1410  * Two cases:
 1411  *     a variable:  point arg1 at it.
 1412  *     a constant:  pass it in arg2.
 1413  */
 1414 
 1415 int
 1416 sysctl_handle_long(SYSCTL_HANDLER_ARGS)
 1417 {
 1418         int error = 0;
 1419         long tmplong;
 1420 #ifdef SCTL_MASK32
 1421         int tmpint;
 1422 #endif
 1423 
 1424         /*
 1425          * Attempt to get a coherent snapshot by making a copy of the data.
 1426          */
 1427         if (arg1)
 1428                 tmplong = *(long *)arg1;
 1429         else
 1430                 tmplong = arg2;
 1431 #ifdef SCTL_MASK32
 1432         if (req->flags & SCTL_MASK32) {
 1433                 tmpint = tmplong;
 1434                 error = SYSCTL_OUT(req, &tmpint, sizeof(int));
 1435         } else
 1436 #endif
 1437                 error = SYSCTL_OUT(req, &tmplong, sizeof(long));
 1438 
 1439         if (error || !req->newptr)
 1440                 return (error);
 1441 
 1442         if (!arg1)
 1443                 error = EPERM;
 1444 #ifdef SCTL_MASK32
 1445         else if (req->flags & SCTL_MASK32) {
 1446                 error = SYSCTL_IN(req, &tmpint, sizeof(int));
 1447                 *(long *)arg1 = (long)tmpint;
 1448         }
 1449 #endif
 1450         else
 1451                 error = SYSCTL_IN(req, arg1, sizeof(long));
 1452         return (error);
 1453 }
 1454 
 1455 /*
 1456  * Handle a 64 bit int, signed or unsigned.
 1457  * Two cases:
 1458  *     a variable:  point arg1 at it.
 1459  *     a constant:  pass it in arg2.
 1460  */
 1461 int
 1462 sysctl_handle_64(SYSCTL_HANDLER_ARGS)
 1463 {
 1464         int error = 0;
 1465         uint64_t tmpout;
 1466 
 1467         /*
 1468          * Attempt to get a coherent snapshot by making a copy of the data.
 1469          */
 1470         if (arg1)
 1471                 tmpout = *(uint64_t *)arg1;
 1472         else
 1473                 tmpout = arg2;
 1474         error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));
 1475 
 1476         if (error || !req->newptr)
 1477                 return (error);
 1478 
 1479         if (!arg1)
 1480                 error = EPERM;
 1481         else
 1482                 error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
 1483         return (error);
 1484 }
 1485 
 1486 /*
 1487  * Handle our generic '\0' terminated 'C' string.
 1488  * Two cases:
 1489  *      a variable string:  point arg1 at it, arg2 is max length.
 1490  *      a constant string:  point arg1 at it, arg2 is zero.
 1491  */
 1492 
 1493 int
 1494 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 1495 {
 1496         size_t outlen;
 1497         int error = 0, ro_string = 0;
 1498 
 1499         /*
 1500          * A zero-length buffer indicates a fixed size read-only
 1501          * string:
 1502          */
 1503         if (arg2 == 0) {
 1504                 arg2 = strlen((char *)arg1) + 1;
 1505                 ro_string = 1;
 1506         }
 1507 
 1508         if (req->oldptr != NULL) {
 1509                 char *tmparg;
 1510 
 1511                 if (ro_string) {
 1512                         tmparg = arg1;
 1513                 } else {
 1514                         /* try to make a coherent snapshot of the string */
 1515                         tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);
 1516                         memcpy(tmparg, arg1, arg2);
 1517                 }
 1518 
 1519                 outlen = strnlen(tmparg, arg2 - 1) + 1;
 1520                 error = SYSCTL_OUT(req, tmparg, outlen);
 1521 
 1522                 if (!ro_string)
 1523                         free(tmparg, M_SYSCTLTMP);
 1524         } else {
 1525                 outlen = strnlen((char *)arg1, arg2 - 1) + 1;
 1526                 error = SYSCTL_OUT(req, NULL, outlen);
 1527         }
 1528         if (error || !req->newptr)
 1529                 return (error);
 1530 
 1531         if ((req->newlen - req->newidx) >= arg2) {
 1532                 error = EINVAL;
 1533         } else {
 1534                 arg2 = (req->newlen - req->newidx);
 1535                 error = SYSCTL_IN(req, arg1, arg2);
 1536                 ((char *)arg1)[arg2] = '\0';
 1537         }
 1538         return (error);
 1539 }
 1540 
 1541 /*
 1542  * Handle any kind of opaque data.
 1543  * arg1 points to it, arg2 is the size.
 1544  */
 1545 
 1546 int
 1547 sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
 1548 {
 1549         int error, tries;
 1550         u_int generation;
 1551         struct sysctl_req req2;
 1552 
 1553         /*
 1554          * Attempt to get a coherent snapshot, by using the thread
 1555          * pre-emption counter updated from within mi_switch() to
 1556          * determine if we were pre-empted during a bcopy() or
 1557          * copyout(). Make 3 attempts at doing this before giving up.
 1558          * If we encounter an error, stop immediately.
 1559          */
 1560         tries = 0;
 1561         req2 = *req;
 1562 retry:
 1563         generation = curthread->td_generation;
 1564         error = SYSCTL_OUT(req, arg1, arg2);
 1565         if (error)
 1566                 return (error);
 1567         tries++;
 1568         if (generation != curthread->td_generation && tries < 3) {
 1569                 *req = req2;
 1570                 goto retry;
 1571         }
 1572 
 1573         error = SYSCTL_IN(req, arg1, arg2);
 1574 
 1575         return (error);
 1576 }
 1577 
 1578 /*
 1579  * Transfer functions to/from kernel space.
 1580  * XXX: rather untested at this point
 1581  */
 1582 static int
 1583 sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
 1584 {
 1585         size_t i = 0;
 1586 
 1587         if (req->oldptr) {
 1588                 i = l;
 1589                 if (req->oldlen <= req->oldidx)
 1590                         i = 0;
 1591                 else
 1592                         if (i > req->oldlen - req->oldidx)
 1593                                 i = req->oldlen - req->oldidx;
 1594                 if (i > 0)
 1595                         bcopy(p, (char *)req->oldptr + req->oldidx, i);
 1596         }
 1597         req->oldidx += l;
 1598         if (req->oldptr && i != l)
 1599                 return (ENOMEM);
 1600         return (0);
 1601 }
 1602 
 1603 static int
 1604 sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
 1605 {
 1606         if (!req->newptr)
 1607                 return (0);
 1608         if (req->newlen - req->newidx < l)
 1609                 return (EINVAL);
 1610         bcopy((char *)req->newptr + req->newidx, p, l);
 1611         req->newidx += l;
 1612         return (0);
 1613 }
 1614 
 1615 int
 1616 kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1617     size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
 1618 {
 1619         int error = 0;
 1620         struct sysctl_req req;
 1621 
 1622         bzero(&req, sizeof req);
 1623 
 1624         req.td = td;
 1625         req.flags = flags;
 1626 
 1627         if (oldlenp) {
 1628                 req.oldlen = *oldlenp;
 1629         }
 1630         req.validlen = req.oldlen;
 1631 
 1632         if (old) {
 1633                 req.oldptr= old;
 1634         }
 1635 
 1636         if (new != NULL) {
 1637                 req.newlen = newlen;
 1638                 req.newptr = new;
 1639         }
 1640 
 1641         req.oldfunc = sysctl_old_kernel;
 1642         req.newfunc = sysctl_new_kernel;
 1643         req.lock = REQ_UNWIRED;
 1644 
 1645         error = sysctl_root(0, name, namelen, &req);
 1646 
 1647         if (req.lock == REQ_WIRED && req.validlen > 0)
 1648                 vsunlock(req.oldptr, req.validlen);
 1649 
 1650         if (error && error != ENOMEM)
 1651                 return (error);
 1652 
 1653         if (retval) {
 1654                 if (req.oldptr && req.oldidx > req.validlen)
 1655                         *retval = req.validlen;
 1656                 else
 1657                         *retval = req.oldidx;
 1658         }
 1659         return (error);
 1660 }
 1661 
 1662 int
 1663 kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
 1664     void *new, size_t newlen, size_t *retval, int flags)
 1665 {
 1666         int oid[CTL_MAXNAME];
 1667         size_t oidlen, plen;
 1668         int error;
 1669 
 1670         oid[0] = 0;             /* sysctl internal magic */
 1671         oid[1] = 3;             /* name2oid */
 1672         oidlen = sizeof(oid);
 1673 
 1674         error = kernel_sysctl(td, oid, 2, oid, &oidlen,
 1675             (void *)name, strlen(name), &plen, flags);
 1676         if (error)
 1677                 return (error);
 1678 
 1679         error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
 1680             new, newlen, retval, flags);
 1681         return (error);
 1682 }
 1683 
 1684 /*
 1685  * Transfer function to/from user space.
 1686  */
 1687 static int
 1688 sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
 1689 {
 1690         size_t i, len, origidx;
 1691         int error;
 1692 
 1693         origidx = req->oldidx;
 1694         req->oldidx += l;
 1695         if (req->oldptr == NULL)
 1696                 return (0);
 1697         /*
 1698          * If we have not wired the user supplied buffer and we are currently
 1699          * holding locks, drop a witness warning, as it's possible that
 1700          * write operations to the user page can sleep.
 1701          */
 1702         if (req->lock != REQ_WIRED)
 1703                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1704                     "sysctl_old_user()");
 1705         i = l;
 1706         len = req->validlen;
 1707         if (len <= origidx)
 1708                 i = 0;
 1709         else {
 1710                 if (i > len - origidx)
 1711                         i = len - origidx;
 1712                 if (req->lock == REQ_WIRED) {
 1713                         error = copyout_nofault(p, (char *)req->oldptr +
 1714                             origidx, i);
 1715                 } else
 1716                         error = copyout(p, (char *)req->oldptr + origidx, i);
 1717                 if (error != 0)
 1718                         return (error);
 1719         }
 1720         if (i < l)
 1721                 return (ENOMEM);
 1722         return (0);
 1723 }
 1724 
 1725 static int
 1726 sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
 1727 {
 1728         int error;
 1729 
 1730         if (!req->newptr)
 1731                 return (0);
 1732         if (req->newlen - req->newidx < l)
 1733                 return (EINVAL);
 1734         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1735             "sysctl_new_user()");
 1736         error = copyin((char *)req->newptr + req->newidx, p, l);
 1737         req->newidx += l;
 1738         return (error);
 1739 }
 1740 
 1741 /*
 1742  * Wire the user space destination buffer.  If set to a value greater than
 1743  * zero, the len parameter limits the maximum amount of wired memory.
 1744  */
 1745 int
 1746 sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
 1747 {
 1748         int ret;
 1749         size_t wiredlen;
 1750 
 1751         wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
 1752         ret = 0;
 1753         if (req->lock != REQ_WIRED && req->oldptr &&
 1754             req->oldfunc == sysctl_old_user) {
 1755                 if (wiredlen != 0) {
 1756                         ret = vslock(req->oldptr, wiredlen);
 1757                         if (ret != 0) {
 1758                                 if (ret != ENOMEM)
 1759                                         return (ret);
 1760                                 wiredlen = 0;
 1761                         }
 1762                 }
 1763                 req->lock = REQ_WIRED;
 1764                 req->validlen = wiredlen;
 1765         }
 1766         return (0);
 1767 }
 1768 
 1769 int
 1770 sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
 1771     int *nindx, struct sysctl_req *req)
 1772 {
 1773         struct sysctl_oid_list *lsp;
 1774         struct sysctl_oid *oid;
 1775         int indx;
 1776 
 1777         SYSCTL_ASSERT_LOCKED();
 1778         lsp = &sysctl__children;
 1779         indx = 0;
 1780         while (indx < CTL_MAXNAME) {
 1781                 SLIST_FOREACH(oid, lsp, oid_link) {
 1782                         if (oid->oid_number == name[indx])
 1783                                 break;
 1784                 }
 1785                 if (oid == NULL)
 1786                         return (ENOENT);
 1787 
 1788                 indx++;
 1789                 if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1790                         if (oid->oid_handler != NULL || indx == namelen) {
 1791                                 *noid = oid;
 1792                                 if (nindx != NULL)
 1793                                         *nindx = indx;
 1794                                 KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
 1795                                     ("%s found DYING node %p", __func__, oid));
 1796                                 return (0);
 1797                         }
 1798                         lsp = SYSCTL_CHILDREN(oid);
 1799                 } else if (indx == namelen) {
 1800                         if ((oid->oid_kind & CTLFLAG_DORMANT) != 0)
 1801                                 return (ENOENT);
 1802                         *noid = oid;
 1803                         if (nindx != NULL)
 1804                                 *nindx = indx;
 1805                         KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
 1806                             ("%s found DYING node %p", __func__, oid));
 1807                         return (0);
 1808                 } else {
 1809                         return (ENOTDIR);
 1810                 }
 1811         }
 1812         return (ENOENT);
 1813 }
 1814 
 1815 /*
 1816  * Traverse our tree, and find the right node, execute whatever it points
 1817  * to, and return the resulting error code.
 1818  */
 1819 
 1820 static int
 1821 sysctl_root(SYSCTL_HANDLER_ARGS)
 1822 {
 1823         struct sysctl_oid *oid;
 1824         struct rm_priotracker tracker;
 1825         int error, indx, lvl;
 1826 
 1827         SYSCTL_RLOCK(&tracker);
 1828 
 1829         error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
 1830         if (error)
 1831                 goto out;
 1832 
 1833         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1834                 /*
 1835                  * You can't call a sysctl when it's a node, but has
 1836                  * no handler.  Inform the user that it's a node.
 1837                  * The indx may or may not be the same as namelen.
 1838                  */
 1839                 if (oid->oid_handler == NULL) {
 1840                         error = EISDIR;
 1841                         goto out;
 1842                 }
 1843         }
 1844 
 1845         /* Is this sysctl writable? */
 1846         if (req->newptr && !(oid->oid_kind & CTLFLAG_WR)) {
 1847                 error = EPERM;
 1848                 goto out;
 1849         }
 1850 
 1851         KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));
 1852 
 1853 #ifdef CAPABILITY_MODE
 1854         /*
 1855          * If the process is in capability mode, then don't permit reading or
 1856          * writing unless specifically granted for the node.
 1857          */
 1858         if (IN_CAPABILITY_MODE(req->td)) {
 1859                 if ((req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD)) ||
 1860                     (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))) {
 1861                         error = EPERM;
 1862                         goto out;
 1863                 }
 1864         }
 1865 #endif
 1866 
 1867         /* Is this sysctl sensitive to securelevels? */
 1868         if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
 1869                 lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
 1870                 error = securelevel_gt(req->td->td_ucred, lvl);
 1871                 if (error)
 1872                         goto out;
 1873         }
 1874 
 1875         /* Is this sysctl writable by only privileged users? */
 1876         if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
 1877                 int priv;
 1878 
 1879                 if (oid->oid_kind & CTLFLAG_PRISON)
 1880                         priv = PRIV_SYSCTL_WRITEJAIL;
 1881 #ifdef VIMAGE
 1882                 else if ((oid->oid_kind & CTLFLAG_VNET) &&
 1883                      prison_owns_vnet(req->td->td_ucred))
 1884                         priv = PRIV_SYSCTL_WRITEJAIL;
 1885 #endif
 1886                 else
 1887                         priv = PRIV_SYSCTL_WRITE;
 1888                 error = priv_check(req->td, priv);
 1889                 if (error)
 1890                         goto out;
 1891         }
 1892 
 1893         if (!oid->oid_handler) {
 1894                 error = EINVAL;
 1895                 goto out;
 1896         }
 1897 
 1898         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1899                 arg1 = (int *)arg1 + indx;
 1900                 arg2 -= indx;
 1901         } else {
 1902                 arg1 = oid->oid_arg1;
 1903                 arg2 = oid->oid_arg2;
 1904         }
 1905 #ifdef MAC
 1906         error = mac_system_check_sysctl(req->td->td_ucred, oid, arg1, arg2,
 1907             req);
 1908         if (error != 0)
 1909                 goto out;
 1910 #endif
 1911 #ifdef VIMAGE
 1912         if ((oid->oid_kind & CTLFLAG_VNET) && arg1 != NULL)
 1913                 arg1 = (void *)(curvnet->vnet_data_base + (uintptr_t)arg1);
 1914 #endif
 1915         error = sysctl_root_handler_locked(oid, arg1, arg2, req, &tracker);
 1916 
 1917 out:
 1918         SYSCTL_RUNLOCK(&tracker);
 1919         return (error);
 1920 }
 1921 
 1922 #ifndef _SYS_SYSPROTO_H_
 1923 struct sysctl_args {
 1924         int     *name;
 1925         u_int   namelen;
 1926         void    *old;
 1927         size_t  *oldlenp;
 1928         void    *new;
 1929         size_t  newlen;
 1930 };
 1931 #endif
 1932 int
 1933 sys___sysctl(struct thread *td, struct sysctl_args *uap)
 1934 {
 1935         int error, i, name[CTL_MAXNAME];
 1936         size_t j;
 1937 
 1938         if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
 1939                 return (EINVAL);
 1940 
 1941         error = copyin(uap->name, &name, uap->namelen * sizeof(int));
 1942         if (error)
 1943                 return (error);
 1944 
 1945         error = userland_sysctl(td, name, uap->namelen,
 1946                 uap->old, uap->oldlenp, 0,
 1947                 uap->new, uap->newlen, &j, 0);
 1948         if (error && error != ENOMEM)
 1949                 return (error);
 1950         if (uap->oldlenp) {
 1951                 i = copyout(&j, uap->oldlenp, sizeof(j));
 1952                 if (i)
 1953                         return (i);
 1954         }
 1955         return (error);
 1956 }
 1957 
 1958 /*
 1959  * This is used from various compatibility syscalls too.  That's why name
 1960  * must be in kernel space.
 1961  */
 1962 int
 1963 userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1964     size_t *oldlenp, int inkernel, void *new, size_t newlen, size_t *retval,
 1965     int flags)
 1966 {
 1967         int error = 0, memlocked;
 1968         struct sysctl_req req;
 1969 
 1970         bzero(&req, sizeof req);
 1971 
 1972         req.td = td;
 1973         req.flags = flags;
 1974 
 1975         if (oldlenp) {
 1976                 if (inkernel) {
 1977                         req.oldlen = *oldlenp;
 1978                 } else {
 1979                         error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
 1980                         if (error)
 1981                                 return (error);
 1982                 }
 1983         }
 1984         req.validlen = req.oldlen;
 1985         req.oldptr = old;
 1986 
 1987         if (new != NULL) {
 1988                 req.newlen = newlen;
 1989                 req.newptr = new;
 1990         }
 1991 
 1992         req.oldfunc = sysctl_old_user;
 1993         req.newfunc = sysctl_new_user;
 1994         req.lock = REQ_UNWIRED;
 1995 
 1996 #ifdef KTRACE
 1997         if (KTRPOINT(curthread, KTR_SYSCTL))
 1998                 ktrsysctl(name, namelen);
 1999 #endif
 2000 
 2001         if (req.oldptr && req.oldlen > PAGE_SIZE) {
 2002                 memlocked = 1;
 2003                 sx_xlock(&sysctlmemlock);
 2004         } else
 2005                 memlocked = 0;
 2006         CURVNET_SET(TD_TO_VNET(td));
 2007 
 2008         for (;;) {
 2009                 req.oldidx = 0;
 2010                 req.newidx = 0;
 2011                 error = sysctl_root(0, name, namelen, &req);
 2012                 if (error != EAGAIN)
 2013                         break;
 2014                 kern_yield(PRI_USER);
 2015         }
 2016 
 2017         CURVNET_RESTORE();
 2018 
 2019         if (req.lock == REQ_WIRED && req.validlen > 0)
 2020                 vsunlock(req.oldptr, req.validlen);
 2021         if (memlocked)
 2022                 sx_xunlock(&sysctlmemlock);
 2023 
 2024         if (error && error != ENOMEM)
 2025                 return (error);
 2026 
 2027         if (retval) {
 2028                 if (req.oldptr && req.oldidx > req.validlen)
 2029                         *retval = req.validlen;
 2030                 else
 2031                         *retval = req.oldidx;
 2032         }
 2033         return (error);
 2034 }
 2035 
 2036 /*
 2037  * Drain into a sysctl struct.  The user buffer should be wired if a page
 2038  * fault would cause issue.
 2039  */
 2040 static int
 2041 sbuf_sysctl_drain(void *arg, const char *data, int len)
 2042 {
 2043         struct sysctl_req *req = arg;
 2044         int error;
 2045 
 2046         error = SYSCTL_OUT(req, data, len);
 2047         KASSERT(error >= 0, ("Got unexpected negative value %d", error));
 2048         return (error == 0 ? len : -error);
 2049 }
 2050 
 2051 struct sbuf *
 2052 sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length,
 2053     struct sysctl_req *req)
 2054 {
 2055 
 2056         /* Supply a default buffer size if none given. */
 2057         if (buf == NULL && length == 0)
 2058                 length = 64;
 2059         s = sbuf_new(s, buf, length, SBUF_FIXEDLEN | SBUF_INCLUDENUL);
 2060         sbuf_set_drain(s, sbuf_sysctl_drain, req);
 2061         return (s);
 2062 }

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