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/9.0/sys/kern/kern_sysctl.c 225617 2011-09-16 13:58:51Z kmacy $");
   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/capability.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/sbuf.h>
   58 #include <sys/sx.h>
   59 #include <sys/sysproto.h>
   60 #include <sys/uio.h>
   61 #ifdef KTRACE
   62 #include <sys/ktrace.h>
   63 #endif
   64 
   65 #include <net/vnet.h>
   66 
   67 #include <security/mac/mac_framework.h>
   68 
   69 #include <vm/vm.h>
   70 #include <vm/vm_extern.h>
   71 
   72 static MALLOC_DEFINE(M_SYSCTL, "sysctl", "sysctl internal magic");
   73 static MALLOC_DEFINE(M_SYSCTLOID, "sysctloid", "sysctl dynamic oids");
   74 static MALLOC_DEFINE(M_SYSCTLTMP, "sysctltmp", "sysctl temp output buffer");
   75 
   76 /*
   77  * The sysctllock protects the MIB tree.  It also protects sysctl
   78  * contexts used with dynamic sysctls.  The sysctl_register_oid() and
   79  * sysctl_unregister_oid() routines require the sysctllock to already
   80  * be held, so the sysctl_lock() and sysctl_unlock() routines are
   81  * provided for the few places in the kernel which need to use that
   82  * API rather than using the dynamic API.  Use of the dynamic API is
   83  * strongly encouraged for most code.
   84  *
   85  * The sysctlmemlock is used to limit the amount of user memory wired for
   86  * sysctl requests.  This is implemented by serializing any userland
   87  * sysctl requests larger than a single page via an exclusive lock.
   88  */
   89 static struct sx sysctllock;
   90 static struct sx sysctlmemlock;
   91 
   92 #define SYSCTL_XLOCK()          sx_xlock(&sysctllock)
   93 #define SYSCTL_XUNLOCK()        sx_xunlock(&sysctllock)
   94 #define SYSCTL_ASSERT_XLOCKED() sx_assert(&sysctllock, SA_XLOCKED)
   95 #define SYSCTL_INIT()           sx_init(&sysctllock, "sysctl lock")
   96 #define SYSCTL_SLEEP(ch, wmesg, timo)                                   \
   97                                 sx_sleep(ch, &sysctllock, 0, wmesg, timo)
   98 
   99 static int sysctl_root(SYSCTL_HANDLER_ARGS);
  100 
  101 struct sysctl_oid_list sysctl__children; /* root list */
  102 
  103 static int      sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
  104                     int recurse);
  105 
  106 static struct sysctl_oid *
  107 sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
  108 {
  109         struct sysctl_oid *oidp;
  110 
  111         SYSCTL_ASSERT_XLOCKED();
  112         SLIST_FOREACH(oidp, list, oid_link) {
  113                 if (strcmp(oidp->oid_name, name) == 0) {
  114                         return (oidp);
  115                 }
  116         }
  117         return (NULL);
  118 }
  119 
  120 /*
  121  * Initialization of the MIB tree.
  122  *
  123  * Order by number in each list.
  124  */
  125 void
  126 sysctl_lock(void)
  127 {
  128 
  129         SYSCTL_XLOCK();
  130 }
  131 
  132 void
  133 sysctl_unlock(void)
  134 {
  135 
  136         SYSCTL_XUNLOCK();
  137 }
  138 
  139 void
  140 sysctl_register_oid(struct sysctl_oid *oidp)
  141 {
  142         struct sysctl_oid_list *parent = oidp->oid_parent;
  143         struct sysctl_oid *p;
  144         struct sysctl_oid *q;
  145 
  146         /*
  147          * First check if another oid with the same name already
  148          * exists in the parent's list.
  149          */
  150         SYSCTL_ASSERT_XLOCKED();
  151         p = sysctl_find_oidname(oidp->oid_name, parent);
  152         if (p != NULL) {
  153                 if ((p->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  154                         p->oid_refcnt++;
  155                         return;
  156                 } else {
  157                         printf("can't re-use a leaf (%s)!\n", p->oid_name);
  158                         return;
  159                 }
  160         }
  161         /*
  162          * If this oid has a number OID_AUTO, give it a number which
  163          * is greater than any current oid.
  164          * NOTE: DO NOT change the starting value here, change it in
  165          * <sys/sysctl.h>, and make sure it is at least 256 to
  166          * accomodate e.g. net.inet.raw as a static sysctl node.
  167          */
  168         if (oidp->oid_number == OID_AUTO) {
  169                 static int newoid = CTL_AUTO_START;
  170 
  171                 oidp->oid_number = newoid++;
  172                 if (newoid == 0x7fffffff)
  173                         panic("out of oids");
  174         }
  175 #if 0
  176         else if (oidp->oid_number >= CTL_AUTO_START) {
  177                 /* do not panic; this happens when unregistering sysctl sets */
  178                 printf("static sysctl oid too high: %d", oidp->oid_number);
  179         }
  180 #endif
  181 
  182         /*
  183          * Insert the oid into the parent's list in order.
  184          */
  185         q = NULL;
  186         SLIST_FOREACH(p, parent, oid_link) {
  187                 if (oidp->oid_number < p->oid_number)
  188                         break;
  189                 q = p;
  190         }
  191         if (q)
  192                 SLIST_INSERT_AFTER(q, oidp, oid_link);
  193         else
  194                 SLIST_INSERT_HEAD(parent, oidp, oid_link);
  195 }
  196 
  197 void
  198 sysctl_unregister_oid(struct sysctl_oid *oidp)
  199 {
  200         struct sysctl_oid *p;
  201         int error;
  202 
  203         SYSCTL_ASSERT_XLOCKED();
  204         error = ENOENT;
  205         if (oidp->oid_number == OID_AUTO) {
  206                 error = EINVAL;
  207         } else {
  208                 SLIST_FOREACH(p, oidp->oid_parent, oid_link) {
  209                         if (p == oidp) {
  210                                 SLIST_REMOVE(oidp->oid_parent, oidp,
  211                                     sysctl_oid, oid_link);
  212                                 error = 0;
  213                                 break;
  214                         }
  215                 }
  216         }
  217 
  218         /* 
  219          * This can happen when a module fails to register and is
  220          * being unloaded afterwards.  It should not be a panic()
  221          * for normal use.
  222          */
  223         if (error)
  224                 printf("%s: failed to unregister sysctl\n", __func__);
  225 }
  226 
  227 /* Initialize a new context to keep track of dynamically added sysctls. */
  228 int
  229 sysctl_ctx_init(struct sysctl_ctx_list *c)
  230 {
  231 
  232         if (c == NULL) {
  233                 return (EINVAL);
  234         }
  235 
  236         /*
  237          * No locking here, the caller is responsible for not adding
  238          * new nodes to a context until after this function has
  239          * returned.
  240          */
  241         TAILQ_INIT(c);
  242         return (0);
  243 }
  244 
  245 /* Free the context, and destroy all dynamic oids registered in this context */
  246 int
  247 sysctl_ctx_free(struct sysctl_ctx_list *clist)
  248 {
  249         struct sysctl_ctx_entry *e, *e1;
  250         int error;
  251 
  252         error = 0;
  253         /*
  254          * First perform a "dry run" to check if it's ok to remove oids.
  255          * XXX FIXME
  256          * XXX This algorithm is a hack. But I don't know any
  257          * XXX better solution for now...
  258          */
  259         SYSCTL_XLOCK();
  260         TAILQ_FOREACH(e, clist, link) {
  261                 error = sysctl_remove_oid_locked(e->entry, 0, 0);
  262                 if (error)
  263                         break;
  264         }
  265         /*
  266          * Restore deregistered entries, either from the end,
  267          * or from the place where error occured.
  268          * e contains the entry that was not unregistered
  269          */
  270         if (error)
  271                 e1 = TAILQ_PREV(e, sysctl_ctx_list, link);
  272         else
  273                 e1 = TAILQ_LAST(clist, sysctl_ctx_list);
  274         while (e1 != NULL) {
  275                 sysctl_register_oid(e1->entry);
  276                 e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
  277         }
  278         if (error) {
  279                 SYSCTL_XUNLOCK();
  280                 return(EBUSY);
  281         }
  282         /* Now really delete the entries */
  283         e = TAILQ_FIRST(clist);
  284         while (e != NULL) {
  285                 e1 = TAILQ_NEXT(e, link);
  286                 error = sysctl_remove_oid_locked(e->entry, 1, 0);
  287                 if (error)
  288                         panic("sysctl_remove_oid: corrupt tree, entry: %s",
  289                             e->entry->oid_name);
  290                 free(e, M_SYSCTLOID);
  291                 e = e1;
  292         }
  293         SYSCTL_XUNLOCK();
  294         return (error);
  295 }
  296 
  297 /* Add an entry to the context */
  298 struct sysctl_ctx_entry *
  299 sysctl_ctx_entry_add(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  300 {
  301         struct sysctl_ctx_entry *e;
  302 
  303         SYSCTL_ASSERT_XLOCKED();
  304         if (clist == NULL || oidp == NULL)
  305                 return(NULL);
  306         e = malloc(sizeof(struct sysctl_ctx_entry), M_SYSCTLOID, M_WAITOK);
  307         e->entry = oidp;
  308         TAILQ_INSERT_HEAD(clist, e, link);
  309         return (e);
  310 }
  311 
  312 /* Find an entry in the context */
  313 struct sysctl_ctx_entry *
  314 sysctl_ctx_entry_find(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  315 {
  316         struct sysctl_ctx_entry *e;
  317 
  318         SYSCTL_ASSERT_XLOCKED();
  319         if (clist == NULL || oidp == NULL)
  320                 return(NULL);
  321         TAILQ_FOREACH(e, clist, link) {
  322                 if(e->entry == oidp)
  323                         return(e);
  324         }
  325         return (e);
  326 }
  327 
  328 /*
  329  * Delete an entry from the context.
  330  * NOTE: this function doesn't free oidp! You have to remove it
  331  * with sysctl_remove_oid().
  332  */
  333 int
  334 sysctl_ctx_entry_del(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
  335 {
  336         struct sysctl_ctx_entry *e;
  337 
  338         if (clist == NULL || oidp == NULL)
  339                 return (EINVAL);
  340         SYSCTL_XLOCK();
  341         e = sysctl_ctx_entry_find(clist, oidp);
  342         if (e != NULL) {
  343                 TAILQ_REMOVE(clist, e, link);
  344                 SYSCTL_XUNLOCK();
  345                 free(e, M_SYSCTLOID);
  346                 return (0);
  347         } else {
  348                 SYSCTL_XUNLOCK();
  349                 return (ENOENT);
  350         }
  351 }
  352 
  353 /*
  354  * Remove dynamically created sysctl trees.
  355  * oidp - top of the tree to be removed
  356  * del - if 0 - just deregister, otherwise free up entries as well
  357  * recurse - if != 0 traverse the subtree to be deleted
  358  */
  359 int
  360 sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse)
  361 {
  362         int error;
  363 
  364         SYSCTL_XLOCK();
  365         error = sysctl_remove_oid_locked(oidp, del, recurse);
  366         SYSCTL_XUNLOCK();
  367         return (error);
  368 }
  369 
  370 int
  371 sysctl_remove_name(struct sysctl_oid *parent, const char *name,
  372     int del, int recurse)
  373 {
  374         struct sysctl_oid *p, *tmp;
  375         int error;
  376 
  377         error = ENOENT;
  378         SYSCTL_XLOCK();
  379         SLIST_FOREACH_SAFE(p, SYSCTL_CHILDREN(parent), oid_link, tmp) {
  380                 if (strcmp(p->oid_name, name) == 0) {
  381                         error = sysctl_remove_oid_locked(p, del, recurse);
  382                         break;
  383                 }
  384         }
  385         SYSCTL_XUNLOCK();
  386 
  387         return (error);
  388 }
  389 
  390 
  391 static int
  392 sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
  393 {
  394         struct sysctl_oid *p, *tmp;
  395         int error;
  396 
  397         SYSCTL_ASSERT_XLOCKED();
  398         if (oidp == NULL)
  399                 return(EINVAL);
  400         if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
  401                 printf("can't remove non-dynamic nodes!\n");
  402                 return (EINVAL);
  403         }
  404         /*
  405          * WARNING: normal method to do this should be through
  406          * sysctl_ctx_free(). Use recursing as the last resort
  407          * method to purge your sysctl tree of leftovers...
  408          * However, if some other code still references these nodes,
  409          * it will panic.
  410          */
  411         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  412                 if (oidp->oid_refcnt == 1) {
  413                         SLIST_FOREACH_SAFE(p,
  414                             SYSCTL_CHILDREN(oidp), oid_link, tmp) {
  415                                 if (!recurse)
  416                                         return (ENOTEMPTY);
  417                                 error = sysctl_remove_oid_locked(p, del,
  418                                     recurse);
  419                                 if (error)
  420                                         return (error);
  421                         }
  422                         if (del)
  423                                 free(SYSCTL_CHILDREN(oidp), M_SYSCTLOID);
  424                 }
  425         }
  426         if (oidp->oid_refcnt > 1 ) {
  427                 oidp->oid_refcnt--;
  428         } else {
  429                 if (oidp->oid_refcnt == 0) {
  430                         printf("Warning: bad oid_refcnt=%u (%s)!\n",
  431                                 oidp->oid_refcnt, oidp->oid_name);
  432                         return (EINVAL);
  433                 }
  434                 sysctl_unregister_oid(oidp);
  435                 if (del) {
  436                         /*
  437                          * Wait for all threads running the handler to drain.
  438                          * This preserves the previous behavior when the
  439                          * sysctl lock was held across a handler invocation,
  440                          * and is necessary for module unload correctness.
  441                          */
  442                         while (oidp->oid_running > 0) {
  443                                 oidp->oid_kind |= CTLFLAG_DYING;
  444                                 SYSCTL_SLEEP(&oidp->oid_running, "oidrm", 0);
  445                         }
  446                         if (oidp->oid_descr)
  447                                 free((void *)(uintptr_t)(const void *)oidp->oid_descr, M_SYSCTLOID);
  448                         free((void *)(uintptr_t)(const void *)oidp->oid_name,
  449                              M_SYSCTLOID);
  450                         free(oidp, M_SYSCTLOID);
  451                 }
  452         }
  453         return (0);
  454 }
  455 /*
  456  * Create new sysctls at run time.
  457  * clist may point to a valid context initialized with sysctl_ctx_init().
  458  */
  459 struct sysctl_oid *
  460 sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
  461         int number, const char *name, int kind, void *arg1, intptr_t arg2,
  462         int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr)
  463 {
  464         struct sysctl_oid *oidp;
  465         ssize_t len;
  466         char *newname;
  467 
  468         /* You have to hook up somewhere.. */
  469         if (parent == NULL)
  470                 return(NULL);
  471         /* Check if the node already exists, otherwise create it */
  472         SYSCTL_XLOCK();
  473         oidp = sysctl_find_oidname(name, parent);
  474         if (oidp != NULL) {
  475                 if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
  476                         oidp->oid_refcnt++;
  477                         /* Update the context */
  478                         if (clist != NULL)
  479                                 sysctl_ctx_entry_add(clist, oidp);
  480                         SYSCTL_XUNLOCK();
  481                         return (oidp);
  482                 } else {
  483                         SYSCTL_XUNLOCK();
  484                         printf("can't re-use a leaf (%s)!\n", name);
  485                         return (NULL);
  486                 }
  487         }
  488         oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
  489         oidp->oid_parent = parent;
  490         SLIST_NEXT(oidp, oid_link) = NULL;
  491         oidp->oid_number = number;
  492         oidp->oid_refcnt = 1;
  493         len = strlen(name);
  494         newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
  495         bcopy(name, newname, len + 1);
  496         newname[len] = '\0';
  497         oidp->oid_name = newname;
  498         oidp->oid_handler = handler;
  499         oidp->oid_kind = CTLFLAG_DYN | kind;
  500         if ((kind & CTLTYPE) == CTLTYPE_NODE) {
  501                 /* Allocate space for children */
  502                 SYSCTL_CHILDREN_SET(oidp, malloc(sizeof(struct sysctl_oid_list),
  503                     M_SYSCTLOID, M_WAITOK));
  504                 SLIST_INIT(SYSCTL_CHILDREN(oidp));
  505                 oidp->oid_arg2 = arg2;
  506         } else {
  507                 oidp->oid_arg1 = arg1;
  508                 oidp->oid_arg2 = arg2;
  509         }
  510         oidp->oid_fmt = fmt;
  511         if (descr) {
  512                 int len = strlen(descr) + 1;
  513                 oidp->oid_descr = malloc(len, M_SYSCTLOID, M_WAITOK);
  514                 if (oidp->oid_descr)
  515                         strcpy((char *)(uintptr_t)(const void *)oidp->oid_descr, descr);
  516         }
  517         /* Update the context, if used */
  518         if (clist != NULL)
  519                 sysctl_ctx_entry_add(clist, oidp);
  520         /* Register this oid */
  521         sysctl_register_oid(oidp);
  522         SYSCTL_XUNLOCK();
  523         return (oidp);
  524 }
  525 
  526 /*
  527  * Rename an existing oid.
  528  */
  529 void
  530 sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
  531 {
  532         ssize_t len;
  533         char *newname;
  534         void *oldname;
  535 
  536         len = strlen(name);
  537         newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
  538         bcopy(name, newname, len + 1);
  539         newname[len] = '\0';
  540         SYSCTL_XLOCK();
  541         oldname = (void *)(uintptr_t)(const void *)oidp->oid_name;
  542         oidp->oid_name = newname;
  543         SYSCTL_XUNLOCK();
  544         free(oldname, M_SYSCTLOID);
  545 }
  546 
  547 /*
  548  * Reparent an existing oid.
  549  */
  550 int
  551 sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
  552 {
  553         struct sysctl_oid *oidp;
  554 
  555         SYSCTL_XLOCK();
  556         if (oid->oid_parent == parent) {
  557                 SYSCTL_XUNLOCK();
  558                 return (0);
  559         }
  560         oidp = sysctl_find_oidname(oid->oid_name, parent);
  561         if (oidp != NULL) {
  562                 SYSCTL_XUNLOCK();
  563                 return (EEXIST);
  564         }
  565         sysctl_unregister_oid(oid);
  566         oid->oid_parent = parent;
  567         oid->oid_number = OID_AUTO;
  568         sysctl_register_oid(oid);
  569         SYSCTL_XUNLOCK();
  570         return (0);
  571 }
  572 
  573 /*
  574  * Register the kernel's oids on startup.
  575  */
  576 SET_DECLARE(sysctl_set, struct sysctl_oid);
  577 
  578 static void
  579 sysctl_register_all(void *arg)
  580 {
  581         struct sysctl_oid **oidp;
  582 
  583         sx_init(&sysctlmemlock, "sysctl mem");
  584         SYSCTL_INIT();
  585         SYSCTL_XLOCK();
  586         SET_FOREACH(oidp, sysctl_set)
  587                 sysctl_register_oid(*oidp);
  588         SYSCTL_XUNLOCK();
  589 }
  590 SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);
  591 
  592 /*
  593  * "Staff-functions"
  594  *
  595  * These functions implement a presently undocumented interface 
  596  * used by the sysctl program to walk the tree, and get the type
  597  * so it can print the value.
  598  * This interface is under work and consideration, and should probably
  599  * be killed with a big axe by the first person who can find the time.
  600  * (be aware though, that the proper interface isn't as obvious as it
  601  * may seem, there are various conflicting requirements.
  602  *
  603  * {0,0}        printf the entire MIB-tree.
  604  * {0,1,...}    return the name of the "..." OID.
  605  * {0,2,...}    return the next OID.
  606  * {0,3}        return the OID of the name in "new"
  607  * {0,4,...}    return the kind & format info for the "..." OID.
  608  * {0,5,...}    return the description the "..." OID.
  609  */
  610 
  611 #ifdef SYSCTL_DEBUG
  612 static void
  613 sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
  614 {
  615         int k;
  616         struct sysctl_oid *oidp;
  617 
  618         SYSCTL_ASSERT_XLOCKED();
  619         SLIST_FOREACH(oidp, l, oid_link) {
  620 
  621                 for (k=0; k<i; k++)
  622                         printf(" ");
  623 
  624                 printf("%d %s ", oidp->oid_number, oidp->oid_name);
  625 
  626                 printf("%c%c",
  627                         oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
  628                         oidp->oid_kind & CTLFLAG_WR ? 'W':' ');
  629 
  630                 if (oidp->oid_handler)
  631                         printf(" *Handler");
  632 
  633                 switch (oidp->oid_kind & CTLTYPE) {
  634                         case CTLTYPE_NODE:
  635                                 printf(" Node\n");
  636                                 if (!oidp->oid_handler) {
  637                                         sysctl_sysctl_debug_dump_node(
  638                                                 oidp->oid_arg1, i+2);
  639                                 }
  640                                 break;
  641                         case CTLTYPE_INT:    printf(" Int\n"); break;
  642                         case CTLTYPE_UINT:   printf(" u_int\n"); break;
  643                         case CTLTYPE_LONG:   printf(" Long\n"); break;
  644                         case CTLTYPE_ULONG:  printf(" u_long\n"); break;
  645                         case CTLTYPE_STRING: printf(" String\n"); break;
  646                         case CTLTYPE_U64:    printf(" uint64_t\n"); break;
  647                         case CTLTYPE_S64:    printf(" int64_t\n"); break;
  648                         case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
  649                         default:             printf("\n");
  650                 }
  651 
  652         }
  653 }
  654 
  655 static int
  656 sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
  657 {
  658         int error;
  659 
  660         error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
  661         if (error)
  662                 return (error);
  663         SYSCTL_XLOCK();
  664         sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
  665         SYSCTL_XUNLOCK();
  666         return (ENOENT);
  667 }
  668 
  669 SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD,
  670         0, 0, sysctl_sysctl_debug, "-", "");
  671 #endif
  672 
  673 static int
  674 sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
  675 {
  676         int *name = (int *) arg1;
  677         u_int namelen = arg2;
  678         int error = 0;
  679         struct sysctl_oid *oid;
  680         struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
  681         char buf[10];
  682 
  683         SYSCTL_XLOCK();
  684         while (namelen) {
  685                 if (!lsp) {
  686                         snprintf(buf,sizeof(buf),"%d",*name);
  687                         if (req->oldidx)
  688                                 error = SYSCTL_OUT(req, ".", 1);
  689                         if (!error)
  690                                 error = SYSCTL_OUT(req, buf, strlen(buf));
  691                         if (error)
  692                                 goto out;
  693                         namelen--;
  694                         name++;
  695                         continue;
  696                 }
  697                 lsp2 = 0;
  698                 SLIST_FOREACH(oid, lsp, oid_link) {
  699                         if (oid->oid_number != *name)
  700                                 continue;
  701 
  702                         if (req->oldidx)
  703                                 error = SYSCTL_OUT(req, ".", 1);
  704                         if (!error)
  705                                 error = SYSCTL_OUT(req, oid->oid_name,
  706                                         strlen(oid->oid_name));
  707                         if (error)
  708                                 goto out;
  709 
  710                         namelen--;
  711                         name++;
  712 
  713                         if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
  714                                 break;
  715 
  716                         if (oid->oid_handler)
  717                                 break;
  718 
  719                         lsp2 = SYSCTL_CHILDREN(oid);
  720                         break;
  721                 }
  722                 lsp = lsp2;
  723         }
  724         error = SYSCTL_OUT(req, "", 1);
  725  out:
  726         SYSCTL_XUNLOCK();
  727         return (error);
  728 }
  729 
  730 /*
  731  * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
  732  * capability mode.
  733  */
  734 static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD | CTLFLAG_CAPRD,
  735     sysctl_sysctl_name, "");
  736 
  737 static int
  738 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
  739         int *next, int *len, int level, struct sysctl_oid **oidpp)
  740 {
  741         struct sysctl_oid *oidp;
  742 
  743         SYSCTL_ASSERT_XLOCKED();
  744         *len = level;
  745         SLIST_FOREACH(oidp, lsp, oid_link) {
  746                 *next = oidp->oid_number;
  747                 *oidpp = oidp;
  748 
  749                 if (oidp->oid_kind & CTLFLAG_SKIP)
  750                         continue;
  751 
  752                 if (!namelen) {
  753                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
  754                                 return (0);
  755                         if (oidp->oid_handler) 
  756                                 /* We really should call the handler here...*/
  757                                 return (0);
  758                         lsp = SYSCTL_CHILDREN(oidp);
  759                         if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1, 
  760                                 len, level+1, oidpp))
  761                                 return (0);
  762                         goto emptynode;
  763                 }
  764 
  765                 if (oidp->oid_number < *name)
  766                         continue;
  767 
  768                 if (oidp->oid_number > *name) {
  769                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  770                                 return (0);
  771                         if (oidp->oid_handler)
  772                                 return (0);
  773                         lsp = SYSCTL_CHILDREN(oidp);
  774                         if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, 
  775                                 next+1, len, level+1, oidpp))
  776                                 return (0);
  777                         goto next;
  778                 }
  779                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  780                         continue;
  781 
  782                 if (oidp->oid_handler)
  783                         continue;
  784 
  785                 lsp = SYSCTL_CHILDREN(oidp);
  786                 if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1, 
  787                         len, level+1, oidpp))
  788                         return (0);
  789         next:
  790                 namelen = 1;
  791         emptynode:
  792                 *len = level;
  793         }
  794         return (1);
  795 }
  796 
  797 static int
  798 sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
  799 {
  800         int *name = (int *) arg1;
  801         u_int namelen = arg2;
  802         int i, j, error;
  803         struct sysctl_oid *oid;
  804         struct sysctl_oid_list *lsp = &sysctl__children;
  805         int newoid[CTL_MAXNAME];
  806 
  807         SYSCTL_XLOCK();
  808         i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
  809         SYSCTL_XUNLOCK();
  810         if (i)
  811                 return (ENOENT);
  812         error = SYSCTL_OUT(req, newoid, j * sizeof (int));
  813         return (error);
  814 }
  815 
  816 /*
  817  * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
  818  * capability mode.
  819  */
  820 static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD | CTLFLAG_CAPRD,
  821     sysctl_sysctl_next, "");
  822 
  823 static int
  824 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
  825 {
  826         int i;
  827         struct sysctl_oid *oidp;
  828         struct sysctl_oid_list *lsp = &sysctl__children;
  829         char *p;
  830 
  831         SYSCTL_ASSERT_XLOCKED();
  832 
  833         if (!*name)
  834                 return (ENOENT);
  835 
  836         p = name + strlen(name) - 1 ;
  837         if (*p == '.')
  838                 *p = '\0';
  839 
  840         *len = 0;
  841 
  842         for (p = name; *p && *p != '.'; p++) 
  843                 ;
  844         i = *p;
  845         if (i == '.')
  846                 *p = '\0';
  847 
  848         oidp = SLIST_FIRST(lsp);
  849 
  850         while (oidp && *len < CTL_MAXNAME) {
  851                 if (strcmp(name, oidp->oid_name)) {
  852                         oidp = SLIST_NEXT(oidp, oid_link);
  853                         continue;
  854                 }
  855                 *oid++ = oidp->oid_number;
  856                 (*len)++;
  857 
  858                 if (!i) {
  859                         if (oidpp)
  860                                 *oidpp = oidp;
  861                         return (0);
  862                 }
  863 
  864                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
  865                         break;
  866 
  867                 if (oidp->oid_handler)
  868                         break;
  869 
  870                 lsp = SYSCTL_CHILDREN(oidp);
  871                 oidp = SLIST_FIRST(lsp);
  872                 name = p+1;
  873                 for (p = name; *p && *p != '.'; p++) 
  874                                 ;
  875                 i = *p;
  876                 if (i == '.')
  877                         *p = '\0';
  878         }
  879         return (ENOENT);
  880 }
  881 
  882 static int
  883 sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
  884 {
  885         char *p;
  886         int error, oid[CTL_MAXNAME], len = 0;
  887         struct sysctl_oid *op = 0;
  888 
  889         if (!req->newlen) 
  890                 return (ENOENT);
  891         if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
  892                 return (ENAMETOOLONG);
  893 
  894         p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
  895 
  896         error = SYSCTL_IN(req, p, req->newlen);
  897         if (error) {
  898                 free(p, M_SYSCTL);
  899                 return (error);
  900         }
  901 
  902         p [req->newlen] = '\0';
  903 
  904         SYSCTL_XLOCK();
  905         error = name2oid(p, oid, &len, &op);
  906         SYSCTL_XUNLOCK();
  907 
  908         free(p, M_SYSCTL);
  909 
  910         if (error)
  911                 return (error);
  912 
  913         error = SYSCTL_OUT(req, oid, len * sizeof *oid);
  914         return (error);
  915 }
  916 
  917 /*
  918  * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
  919  * capability mode.
  920  */
  921 SYSCTL_PROC(_sysctl, 3, name2oid,
  922     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE
  923     | CTLFLAG_CAPRW, 0, 0, sysctl_sysctl_name2oid, "I", "");
  924 
  925 static int
  926 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
  927 {
  928         struct sysctl_oid *oid;
  929         int error;
  930 
  931         SYSCTL_XLOCK();
  932         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
  933         if (error)
  934                 goto out;
  935 
  936         if (oid->oid_fmt == NULL) {
  937                 error = ENOENT;
  938                 goto out;
  939         }
  940         error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
  941         if (error)
  942                 goto out;
  943         error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
  944  out:
  945         SYSCTL_XUNLOCK();
  946         return (error);
  947 }
  948 
  949 
  950 static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
  951     sysctl_sysctl_oidfmt, "");
  952 
  953 static int
  954 sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
  955 {
  956         struct sysctl_oid *oid;
  957         int error;
  958 
  959         SYSCTL_XLOCK();
  960         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
  961         if (error)
  962                 goto out;
  963 
  964         if (oid->oid_descr == NULL) {
  965                 error = ENOENT;
  966                 goto out;
  967         }
  968         error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
  969  out:
  970         SYSCTL_XUNLOCK();
  971         return (error);
  972 }
  973 
  974 static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD|CTLFLAG_CAPRD,
  975     sysctl_sysctl_oiddescr, "");
  976 
  977 /*
  978  * Default "handler" functions.
  979  */
  980 
  981 /*
  982  * Handle an int, signed or unsigned.
  983  * Two cases:
  984  *     a variable:  point arg1 at it.
  985  *     a constant:  pass it in arg2.
  986  */
  987 
  988 int
  989 sysctl_handle_int(SYSCTL_HANDLER_ARGS)
  990 {
  991         int tmpout, error = 0;
  992 
  993         /*
  994          * Attempt to get a coherent snapshot by making a copy of the data.
  995          */
  996         if (arg1)
  997                 tmpout = *(int *)arg1;
  998         else
  999                 tmpout = arg2;
 1000         error = SYSCTL_OUT(req, &tmpout, sizeof(int));
 1001 
 1002         if (error || !req->newptr)
 1003                 return (error);
 1004 
 1005         if (!arg1)
 1006                 error = EPERM;
 1007         else
 1008                 error = SYSCTL_IN(req, arg1, sizeof(int));
 1009         return (error);
 1010 }
 1011 
 1012 /*
 1013  * Based on on sysctl_handle_int() convert milliseconds into ticks.
 1014  * Note: this is used by TCP.
 1015  */
 1016 
 1017 int
 1018 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
 1019 {
 1020         int error, s, tt;
 1021 
 1022         tt = *(int *)arg1;
 1023         s = (int)((int64_t)tt * 1000 / hz);
 1024 
 1025         error = sysctl_handle_int(oidp, &s, 0, req);
 1026         if (error || !req->newptr)
 1027                 return (error);
 1028 
 1029         tt = (int)((int64_t)s * hz / 1000);
 1030         if (tt < 1)
 1031                 return (EINVAL);
 1032 
 1033         *(int *)arg1 = tt;
 1034         return (0);
 1035 }
 1036 
 1037 
 1038 /*
 1039  * Handle a long, signed or unsigned.  arg1 points to it.
 1040  */
 1041 
 1042 int
 1043 sysctl_handle_long(SYSCTL_HANDLER_ARGS)
 1044 {
 1045         int error = 0;
 1046         long tmplong;
 1047 #ifdef SCTL_MASK32
 1048         int tmpint;
 1049 #endif
 1050 
 1051         /*
 1052          * Attempt to get a coherent snapshot by making a copy of the data.
 1053          */
 1054         if (!arg1)
 1055                 return (EINVAL);
 1056         tmplong = *(long *)arg1;
 1057 #ifdef SCTL_MASK32
 1058         if (req->flags & SCTL_MASK32) {
 1059                 tmpint = tmplong;
 1060                 error = SYSCTL_OUT(req, &tmpint, sizeof(int));
 1061         } else
 1062 #endif
 1063                 error = SYSCTL_OUT(req, &tmplong, sizeof(long));
 1064 
 1065         if (error || !req->newptr)
 1066                 return (error);
 1067 
 1068 #ifdef SCTL_MASK32
 1069         if (req->flags & SCTL_MASK32) {
 1070                 error = SYSCTL_IN(req, &tmpint, sizeof(int));
 1071                 *(long *)arg1 = (long)tmpint;
 1072         } else
 1073 #endif
 1074                 error = SYSCTL_IN(req, arg1, sizeof(long));
 1075         return (error);
 1076 }
 1077 
 1078 /*
 1079  * Handle a 64 bit int, signed or unsigned.  arg1 points to it.
 1080  */
 1081 int
 1082 sysctl_handle_64(SYSCTL_HANDLER_ARGS)
 1083 {
 1084         int error = 0;
 1085         uint64_t tmpout;
 1086 
 1087         /*
 1088          * Attempt to get a coherent snapshot by making a copy of the data.
 1089          */
 1090         if (!arg1)
 1091                 return (EINVAL);
 1092         tmpout = *(uint64_t *)arg1;
 1093         error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));
 1094 
 1095         if (error || !req->newptr)
 1096                 return (error);
 1097 
 1098         error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
 1099         return (error);
 1100 }
 1101 
 1102 /*
 1103  * Handle our generic '\0' terminated 'C' string.
 1104  * Two cases:
 1105  *      a variable string:  point arg1 at it, arg2 is max length.
 1106  *      a constant string:  point arg1 at it, arg2 is zero.
 1107  */
 1108 
 1109 int
 1110 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
 1111 {
 1112         int error=0;
 1113         char *tmparg;
 1114         size_t outlen;
 1115 
 1116         /*
 1117          * Attempt to get a coherent snapshot by copying to a
 1118          * temporary kernel buffer.
 1119          */
 1120 retry:
 1121         outlen = strlen((char *)arg1)+1;
 1122         tmparg = malloc(outlen, M_SYSCTLTMP, M_WAITOK);
 1123 
 1124         if (strlcpy(tmparg, (char *)arg1, outlen) >= outlen) {
 1125                 free(tmparg, M_SYSCTLTMP);
 1126                 goto retry;
 1127         }
 1128 
 1129         error = SYSCTL_OUT(req, tmparg, outlen);
 1130         free(tmparg, M_SYSCTLTMP);
 1131 
 1132         if (error || !req->newptr)
 1133                 return (error);
 1134 
 1135         if ((req->newlen - req->newidx) >= arg2) {
 1136                 error = EINVAL;
 1137         } else {
 1138                 arg2 = (req->newlen - req->newidx);
 1139                 error = SYSCTL_IN(req, arg1, arg2);
 1140                 ((char *)arg1)[arg2] = '\0';
 1141         }
 1142 
 1143         return (error);
 1144 }
 1145 
 1146 /*
 1147  * Handle any kind of opaque data.
 1148  * arg1 points to it, arg2 is the size.
 1149  */
 1150 
 1151 int
 1152 sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
 1153 {
 1154         int error, tries;
 1155         u_int generation;
 1156         struct sysctl_req req2;
 1157 
 1158         /*
 1159          * Attempt to get a coherent snapshot, by using the thread
 1160          * pre-emption counter updated from within mi_switch() to
 1161          * determine if we were pre-empted during a bcopy() or
 1162          * copyout(). Make 3 attempts at doing this before giving up.
 1163          * If we encounter an error, stop immediately.
 1164          */
 1165         tries = 0;
 1166         req2 = *req;
 1167 retry:
 1168         generation = curthread->td_generation;
 1169         error = SYSCTL_OUT(req, arg1, arg2);
 1170         if (error)
 1171                 return (error);
 1172         tries++;
 1173         if (generation != curthread->td_generation && tries < 3) {
 1174                 *req = req2;
 1175                 goto retry;
 1176         }
 1177 
 1178         error = SYSCTL_IN(req, arg1, arg2);
 1179 
 1180         return (error);
 1181 }
 1182 
 1183 /*
 1184  * Transfer functions to/from kernel space.
 1185  * XXX: rather untested at this point
 1186  */
 1187 static int
 1188 sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
 1189 {
 1190         size_t i = 0;
 1191 
 1192         if (req->oldptr) {
 1193                 i = l;
 1194                 if (req->oldlen <= req->oldidx)
 1195                         i = 0;
 1196                 else
 1197                         if (i > req->oldlen - req->oldidx)
 1198                                 i = req->oldlen - req->oldidx;
 1199                 if (i > 0)
 1200                         bcopy(p, (char *)req->oldptr + req->oldidx, i);
 1201         }
 1202         req->oldidx += l;
 1203         if (req->oldptr && i != l)
 1204                 return (ENOMEM);
 1205         return (0);
 1206 }
 1207 
 1208 static int
 1209 sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
 1210 {
 1211         if (!req->newptr)
 1212                 return (0);
 1213         if (req->newlen - req->newidx < l)
 1214                 return (EINVAL);
 1215         bcopy((char *)req->newptr + req->newidx, p, l);
 1216         req->newidx += l;
 1217         return (0);
 1218 }
 1219 
 1220 int
 1221 kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1222     size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
 1223 {
 1224         int error = 0;
 1225         struct sysctl_req req;
 1226 
 1227         bzero(&req, sizeof req);
 1228 
 1229         req.td = td;
 1230         req.flags = flags;
 1231 
 1232         if (oldlenp) {
 1233                 req.oldlen = *oldlenp;
 1234         }
 1235         req.validlen = req.oldlen;
 1236 
 1237         if (old) {
 1238                 req.oldptr= old;
 1239         }
 1240 
 1241         if (new != NULL) {
 1242                 req.newlen = newlen;
 1243                 req.newptr = new;
 1244         }
 1245 
 1246         req.oldfunc = sysctl_old_kernel;
 1247         req.newfunc = sysctl_new_kernel;
 1248         req.lock = REQ_UNWIRED;
 1249 
 1250         SYSCTL_XLOCK();
 1251         error = sysctl_root(0, name, namelen, &req);
 1252         SYSCTL_XUNLOCK();
 1253 
 1254         if (req.lock == REQ_WIRED && req.validlen > 0)
 1255                 vsunlock(req.oldptr, req.validlen);
 1256 
 1257         if (error && error != ENOMEM)
 1258                 return (error);
 1259 
 1260         if (retval) {
 1261                 if (req.oldptr && req.oldidx > req.validlen)
 1262                         *retval = req.validlen;
 1263                 else
 1264                         *retval = req.oldidx;
 1265         }
 1266         return (error);
 1267 }
 1268 
 1269 int
 1270 kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
 1271     void *new, size_t newlen, size_t *retval, int flags)
 1272 {
 1273         int oid[CTL_MAXNAME];
 1274         size_t oidlen, plen;
 1275         int error;
 1276 
 1277         oid[0] = 0;             /* sysctl internal magic */
 1278         oid[1] = 3;             /* name2oid */
 1279         oidlen = sizeof(oid);
 1280 
 1281         error = kernel_sysctl(td, oid, 2, oid, &oidlen,
 1282             (void *)name, strlen(name), &plen, flags);
 1283         if (error)
 1284                 return (error);
 1285 
 1286         error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
 1287             new, newlen, retval, flags);
 1288         return (error);
 1289 }
 1290 
 1291 /*
 1292  * Transfer function to/from user space.
 1293  */
 1294 static int
 1295 sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
 1296 {
 1297         int error = 0;
 1298         size_t i, len, origidx;
 1299 
 1300         origidx = req->oldidx;
 1301         req->oldidx += l;
 1302         if (req->oldptr == NULL)
 1303                 return (0);
 1304         /*
 1305          * If we have not wired the user supplied buffer and we are currently
 1306          * holding locks, drop a witness warning, as it's possible that
 1307          * write operations to the user page can sleep.
 1308          */
 1309         if (req->lock != REQ_WIRED)
 1310                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1311                     "sysctl_old_user()");
 1312         i = l;
 1313         len = req->validlen;
 1314         if (len <= origidx)
 1315                 i = 0;
 1316         else {
 1317                 if (i > len - origidx)
 1318                         i = len - origidx;
 1319                 error = copyout(p, (char *)req->oldptr + origidx, i);
 1320         }
 1321         if (error)
 1322                 return (error);
 1323         if (i < l)
 1324                 return (ENOMEM);
 1325         return (0);
 1326 }
 1327 
 1328 static int
 1329 sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
 1330 {
 1331         int error;
 1332 
 1333         if (!req->newptr)
 1334                 return (0);
 1335         if (req->newlen - req->newidx < l)
 1336                 return (EINVAL);
 1337         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
 1338             "sysctl_new_user()");
 1339         error = copyin((char *)req->newptr + req->newidx, p, l);
 1340         req->newidx += l;
 1341         return (error);
 1342 }
 1343 
 1344 /*
 1345  * Wire the user space destination buffer.  If set to a value greater than
 1346  * zero, the len parameter limits the maximum amount of wired memory.
 1347  */
 1348 int
 1349 sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
 1350 {
 1351         int ret;
 1352         size_t wiredlen;
 1353 
 1354         wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
 1355         ret = 0;
 1356         if (req->lock != REQ_WIRED && req->oldptr &&
 1357             req->oldfunc == sysctl_old_user) {
 1358                 if (wiredlen != 0) {
 1359                         ret = vslock(req->oldptr, wiredlen);
 1360                         if (ret != 0) {
 1361                                 if (ret != ENOMEM)
 1362                                         return (ret);
 1363                                 wiredlen = 0;
 1364                         }
 1365                 }
 1366                 req->lock = REQ_WIRED;
 1367                 req->validlen = wiredlen;
 1368         }
 1369         return (0);
 1370 }
 1371 
 1372 int
 1373 sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
 1374     int *nindx, struct sysctl_req *req)
 1375 {
 1376         struct sysctl_oid_list *lsp;
 1377         struct sysctl_oid *oid;
 1378         int indx;
 1379 
 1380         SYSCTL_ASSERT_XLOCKED();
 1381         lsp = &sysctl__children;
 1382         indx = 0;
 1383         while (indx < CTL_MAXNAME) {
 1384                 SLIST_FOREACH(oid, lsp, oid_link) {
 1385                         if (oid->oid_number == name[indx])
 1386                                 break;
 1387                 }
 1388                 if (oid == NULL)
 1389                         return (ENOENT);
 1390 
 1391                 indx++;
 1392                 if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1393                         if (oid->oid_handler != NULL || indx == namelen) {
 1394                                 *noid = oid;
 1395                                 if (nindx != NULL)
 1396                                         *nindx = indx;
 1397                                 KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
 1398                                     ("%s found DYING node %p", __func__, oid));
 1399                                 return (0);
 1400                         }
 1401                         lsp = SYSCTL_CHILDREN(oid);
 1402                 } else if (indx == namelen) {
 1403                         *noid = oid;
 1404                         if (nindx != NULL)
 1405                                 *nindx = indx;
 1406                         KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
 1407                             ("%s found DYING node %p", __func__, oid));
 1408                         return (0);
 1409                 } else {
 1410                         return (ENOTDIR);
 1411                 }
 1412         }
 1413         return (ENOENT);
 1414 }
 1415 
 1416 /*
 1417  * Traverse our tree, and find the right node, execute whatever it points
 1418  * to, and return the resulting error code.
 1419  */
 1420 
 1421 static int
 1422 sysctl_root(SYSCTL_HANDLER_ARGS)
 1423 {
 1424         struct sysctl_oid *oid;
 1425         int error, indx, lvl;
 1426 
 1427         SYSCTL_ASSERT_XLOCKED();
 1428 
 1429         error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
 1430         if (error)
 1431                 return (error);
 1432 
 1433         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1434                 /*
 1435                  * You can't call a sysctl when it's a node, but has
 1436                  * no handler.  Inform the user that it's a node.
 1437                  * The indx may or may not be the same as namelen.
 1438                  */
 1439                 if (oid->oid_handler == NULL)
 1440                         return (EISDIR);
 1441         }
 1442 
 1443         /* Is this sysctl writable? */
 1444         if (req->newptr && !(oid->oid_kind & CTLFLAG_WR))
 1445                 return (EPERM);
 1446 
 1447         KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));
 1448 
 1449 #ifdef CAPABILITY_MODE
 1450         /*
 1451          * If the process is in capability mode, then don't permit reading or
 1452          * writing unless specifically granted for the node.
 1453          */
 1454         if (IN_CAPABILITY_MODE(req->td)) {
 1455                 if (req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD))
 1456                         return (EPERM);
 1457                 if (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))
 1458                         return (EPERM);
 1459         }
 1460 #endif
 1461 
 1462         /* Is this sysctl sensitive to securelevels? */
 1463         if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
 1464                 lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
 1465                 error = securelevel_gt(req->td->td_ucred, lvl);
 1466                 if (error)
 1467                         return (error);
 1468         }
 1469 
 1470         /* Is this sysctl writable by only privileged users? */
 1471         if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
 1472                 int priv;
 1473 
 1474                 if (oid->oid_kind & CTLFLAG_PRISON)
 1475                         priv = PRIV_SYSCTL_WRITEJAIL;
 1476 #ifdef VIMAGE
 1477                 else if ((oid->oid_kind & CTLFLAG_VNET) &&
 1478                      prison_owns_vnet(req->td->td_ucred))
 1479                         priv = PRIV_SYSCTL_WRITEJAIL;
 1480 #endif
 1481                 else
 1482                         priv = PRIV_SYSCTL_WRITE;
 1483                 error = priv_check(req->td, priv);
 1484                 if (error)
 1485                         return (error);
 1486         }
 1487 
 1488         if (!oid->oid_handler)
 1489                 return (EINVAL);
 1490 
 1491         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 1492                 arg1 = (int *)arg1 + indx;
 1493                 arg2 -= indx;
 1494         } else {
 1495                 arg1 = oid->oid_arg1;
 1496                 arg2 = oid->oid_arg2;
 1497         }
 1498 #ifdef MAC
 1499         error = mac_system_check_sysctl(req->td->td_ucred, oid, arg1, arg2,
 1500             req);
 1501         if (error != 0)
 1502                 return (error);
 1503 #endif
 1504         oid->oid_running++;
 1505         SYSCTL_XUNLOCK();
 1506 
 1507         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
 1508                 mtx_lock(&Giant);
 1509         error = oid->oid_handler(oid, arg1, arg2, req);
 1510         if (!(oid->oid_kind & CTLFLAG_MPSAFE))
 1511                 mtx_unlock(&Giant);
 1512 
 1513         KFAIL_POINT_ERROR(_debug_fail_point, sysctl_running, error);
 1514 
 1515         SYSCTL_XLOCK();
 1516         oid->oid_running--;
 1517         if (oid->oid_running == 0 && (oid->oid_kind & CTLFLAG_DYING) != 0)
 1518                 wakeup(&oid->oid_running);
 1519         return (error);
 1520 }
 1521 
 1522 #ifndef _SYS_SYSPROTO_H_
 1523 struct sysctl_args {
 1524         int     *name;
 1525         u_int   namelen;
 1526         void    *old;
 1527         size_t  *oldlenp;
 1528         void    *new;
 1529         size_t  newlen;
 1530 };
 1531 #endif
 1532 int
 1533 sys___sysctl(struct thread *td, struct sysctl_args *uap)
 1534 {
 1535         int error, i, name[CTL_MAXNAME];
 1536         size_t j;
 1537 
 1538         if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
 1539                 return (EINVAL);
 1540 
 1541         error = copyin(uap->name, &name, uap->namelen * sizeof(int));
 1542         if (error)
 1543                 return (error);
 1544 
 1545         error = userland_sysctl(td, name, uap->namelen,
 1546                 uap->old, uap->oldlenp, 0,
 1547                 uap->new, uap->newlen, &j, 0);
 1548         if (error && error != ENOMEM)
 1549                 return (error);
 1550         if (uap->oldlenp) {
 1551                 i = copyout(&j, uap->oldlenp, sizeof(j));
 1552                 if (i)
 1553                         return (i);
 1554         }
 1555         return (error);
 1556 }
 1557 
 1558 /*
 1559  * This is used from various compatibility syscalls too.  That's why name
 1560  * must be in kernel space.
 1561  */
 1562 int
 1563 userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
 1564     size_t *oldlenp, int inkernel, void *new, size_t newlen, size_t *retval,
 1565     int flags)
 1566 {
 1567         int error = 0, memlocked;
 1568         struct sysctl_req req;
 1569 
 1570         bzero(&req, sizeof req);
 1571 
 1572         req.td = td;
 1573         req.flags = flags;
 1574 
 1575         if (oldlenp) {
 1576                 if (inkernel) {
 1577                         req.oldlen = *oldlenp;
 1578                 } else {
 1579                         error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
 1580                         if (error)
 1581                                 return (error);
 1582                 }
 1583         }
 1584         req.validlen = req.oldlen;
 1585 
 1586         if (old) {
 1587                 if (!useracc(old, req.oldlen, VM_PROT_WRITE))
 1588                         return (EFAULT);
 1589                 req.oldptr= old;
 1590         }
 1591 
 1592         if (new != NULL) {
 1593                 if (!useracc(new, newlen, VM_PROT_READ))
 1594                         return (EFAULT);
 1595                 req.newlen = newlen;
 1596                 req.newptr = new;
 1597         }
 1598 
 1599         req.oldfunc = sysctl_old_user;
 1600         req.newfunc = sysctl_new_user;
 1601         req.lock = REQ_UNWIRED;
 1602 
 1603 #ifdef KTRACE
 1604         if (KTRPOINT(curthread, KTR_SYSCTL))
 1605                 ktrsysctl(name, namelen);
 1606 #endif
 1607 
 1608         if (req.oldlen > PAGE_SIZE) {
 1609                 memlocked = 1;
 1610                 sx_xlock(&sysctlmemlock);
 1611         } else
 1612                 memlocked = 0;
 1613         CURVNET_SET(TD_TO_VNET(td));
 1614 
 1615         for (;;) {
 1616                 req.oldidx = 0;
 1617                 req.newidx = 0;
 1618                 SYSCTL_XLOCK();
 1619                 error = sysctl_root(0, name, namelen, &req);
 1620                 SYSCTL_XUNLOCK();
 1621                 if (error != EAGAIN)
 1622                         break;
 1623                 kern_yield(PRI_USER);
 1624         }
 1625 
 1626         CURVNET_RESTORE();
 1627 
 1628         if (req.lock == REQ_WIRED && req.validlen > 0)
 1629                 vsunlock(req.oldptr, req.validlen);
 1630         if (memlocked)
 1631                 sx_xunlock(&sysctlmemlock);
 1632 
 1633         if (error && error != ENOMEM)
 1634                 return (error);
 1635 
 1636         if (retval) {
 1637                 if (req.oldptr && req.oldidx > req.validlen)
 1638                         *retval = req.validlen;
 1639                 else
 1640                         *retval = req.oldidx;
 1641         }
 1642         return (error);
 1643 }
 1644 
 1645 /*
 1646  * Drain into a sysctl struct.  The user buffer should be wired if a page
 1647  * fault would cause issue.
 1648  */
 1649 static int
 1650 sbuf_sysctl_drain(void *arg, const char *data, int len)
 1651 {
 1652         struct sysctl_req *req = arg;
 1653         int error;
 1654 
 1655         error = SYSCTL_OUT(req, data, len);
 1656         KASSERT(error >= 0, ("Got unexpected negative value %d", error));
 1657         return (error == 0 ? len : -error);
 1658 }
 1659 
 1660 struct sbuf *
 1661 sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length,
 1662     struct sysctl_req *req)
 1663 {
 1664 
 1665         s = sbuf_new(s, buf, length, SBUF_FIXEDLEN);
 1666         sbuf_set_drain(s, sbuf_sysctl_drain, req);
 1667         return (s);
 1668 }

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