sys/kern/kern_sysctl.c

   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  * 3. 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("$FreeBSD$");
  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 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[64];
 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_unregister_oid(struct sysctl_oid *oidp)
 429 {
 430         struct sysctl_oid *p;
 431         int error;
 432
 433         SYSCTL_ASSERT_WLOCKED();
 434         error = ENOENT;
 435         if (oidp->oid_number == OID_AUTO) {
 436                 error = EINVAL;
 437         } else {
 438                 SLIST_FOREACH(p, oidp->oid_parent, oid_link) {
 439                         if (p == oidp) {
 440                                 SLIST_REMOVE(oidp->oid_parent, oidp,
 441                                     sysctl_oid, oid_link);
 442                                 error = 0;
 443                                 break;
 444                         }
 445                 }
 446         }
 447
 448         /*
 449          * This can happen when a module fails to register and is
 450          * being unloaded afterwards.  It should not be a panic()
 451          * for normal use.
 452          */
 453         if (error)
 454                 printf("%s: failed to unregister sysctl\n", __func__);
 455 }
 456
 457 /* Initialize a new context to keep track of dynamically added sysctls. */
 458 int
 459 sysctl_ctx_init(struct sysctl_ctx_list *c)
 460 {
 461
 462         if (c == NULL) {
 463                 return (EINVAL);
 464         }
 465
 466         /*
 467          * No locking here, the caller is responsible for not adding
 468          * new nodes to a context until after this function has
 469          * returned.
 470          */
 471         TAILQ_INIT(c);
 472         return (0);
 473 }
 474
 475 /* Free the context, and destroy all dynamic oids registered in this context */
 476 int
 477 sysctl_ctx_free(struct sysctl_ctx_list *clist)
 478 {
 479         struct sysctl_ctx_entry *e, *e1;
 480         int error;
 481
 482         error = 0;
 483         /*
 484          * First perform a "dry run" to check if it's ok to remove oids.
 485          * XXX FIXME
 486          * XXX This algorithm is a hack. But I don't know any
 487          * XXX better solution for now...
 488          */
 489         SYSCTL_WLOCK();
 490         TAILQ_FOREACH(e, clist, link) {
 491                 error = sysctl_remove_oid_locked(e->entry, 0, 0);
 492                 if (error)
 493                         break;
 494         }
 495         /*
 496          * Restore deregistered entries, either from the end,
 497          * or from the place where error occurred.
 498          * e contains the entry that was not unregistered
 499          */
 500         if (error)
 501                 e1 = TAILQ_PREV(e, sysctl_ctx_list, link);
 502         else
 503                 e1 = TAILQ_LAST(clist, sysctl_ctx_list);
 504         while (e1 != NULL) {
 505                 sysctl_register_oid(e1->entry);
 506                 e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
 507         }
 508         if (error) {
 509                 SYSCTL_WUNLOCK();
 510                 return(EBUSY);
 511         }
 512         /* Now really delete the entries */
 513         e = TAILQ_FIRST(clist);
 514         while (e != NULL) {
 515                 e1 = TAILQ_NEXT(e, link);
 516                 error = sysctl_remove_oid_locked(e->entry, 1, 0);
 517                 if (error)
 518                         panic("sysctl_remove_oid: corrupt tree, entry: %s",
 519                             e->entry->oid_name);
 520                 free(e, M_SYSCTLOID);
 521                 e = e1;
 522         }
 523         SYSCTL_WUNLOCK();
 524         return (error);
 525 }
 526
 527 /* Add an entry to the context */
 528 struct sysctl_ctx_entry *
 529 sysctl_ctx_entry_add(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
 530 {
 531         struct sysctl_ctx_entry *e;
 532
 533         SYSCTL_ASSERT_WLOCKED();
 534         if (clist == NULL || oidp == NULL)
 535                 return(NULL);
 536         e = malloc(sizeof(struct sysctl_ctx_entry), M_SYSCTLOID, M_WAITOK);
 537         e->entry = oidp;
 538         TAILQ_INSERT_HEAD(clist, e, link);
 539         return (e);
 540 }
 541
 542 /* Find an entry in the context */
 543 struct sysctl_ctx_entry *
 544 sysctl_ctx_entry_find(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
 545 {
 546         struct sysctl_ctx_entry *e;
 547
 548         SYSCTL_ASSERT_WLOCKED();
 549         if (clist == NULL || oidp == NULL)
 550                 return(NULL);
 551         TAILQ_FOREACH(e, clist, link) {
 552                 if(e->entry == oidp)
 553                         return(e);
 554         }
 555         return (e);
 556 }
 557
 558 /*
 559  * Delete an entry from the context.
 560  * NOTE: this function doesn't free oidp! You have to remove it
 561  * with sysctl_remove_oid().
 562  */
 563 int
 564 sysctl_ctx_entry_del(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
 565 {
 566         struct sysctl_ctx_entry *e;
 567
 568         if (clist == NULL || oidp == NULL)
 569                 return (EINVAL);
 570         SYSCTL_WLOCK();
 571         e = sysctl_ctx_entry_find(clist, oidp);
 572         if (e != NULL) {
 573                 TAILQ_REMOVE(clist, e, link);
 574                 SYSCTL_WUNLOCK();
 575                 free(e, M_SYSCTLOID);
 576                 return (0);
 577         } else {
 578                 SYSCTL_WUNLOCK();
 579                 return (ENOENT);
 580         }
 581 }
 582
 583 /*
 584  * Remove dynamically created sysctl trees.
 585  * oidp - top of the tree to be removed
 586  * del - if 0 - just deregister, otherwise free up entries as well
 587  * recurse - if != 0 traverse the subtree to be deleted
 588  */
 589 int
 590 sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse)
 591 {
 592         int error;
 593
 594         SYSCTL_WLOCK();
 595         error = sysctl_remove_oid_locked(oidp, del, recurse);
 596         SYSCTL_WUNLOCK();
 597         return (error);
 598 }
 599
 600 int
 601 sysctl_remove_name(struct sysctl_oid *parent, const char *name,
 602     int del, int recurse)
 603 {
 604         struct sysctl_oid *p, *tmp;
 605         int error;
 606
 607         error = ENOENT;
 608         SYSCTL_WLOCK();
 609         SLIST_FOREACH_SAFE(p, SYSCTL_CHILDREN(parent), oid_link, tmp) {
 610                 if (strcmp(p->oid_name, name) == 0) {
 611                         error = sysctl_remove_oid_locked(p, del, recurse);
 612                         break;
 613                 }
 614         }
 615         SYSCTL_WUNLOCK();
 616
 617         return (error);
 618 }
 619
 620
 621 static int
 622 sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
 623 {
 624         struct sysctl_oid *p, *tmp;
 625         int error;
 626
 627         SYSCTL_ASSERT_WLOCKED();
 628         if (oidp == NULL)
 629                 return(EINVAL);
 630         if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
 631                 printf("Warning: can't remove non-dynamic nodes (%s)!\n",
 632                     oidp->oid_name);
 633                 return (EINVAL);
 634         }
 635         /*
 636          * WARNING: normal method to do this should be through
 637          * sysctl_ctx_free(). Use recursing as the last resort
 638          * method to purge your sysctl tree of leftovers...
 639          * However, if some other code still references these nodes,
 640          * it will panic.
 641          */
 642         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 643                 if (oidp->oid_refcnt == 1) {
 644                         SLIST_FOREACH_SAFE(p,
 645                             SYSCTL_CHILDREN(oidp), oid_link, tmp) {
 646                                 if (!recurse) {
 647                                         printf("Warning: failed attempt to "
 648                                             "remove oid %s with child %s\n",
 649                                             oidp->oid_name, p->oid_name);
 650                                         return (ENOTEMPTY);
 651                                 }
 652                                 error = sysctl_remove_oid_locked(p, del,
 653                                     recurse);
 654                                 if (error)
 655                                         return (error);
 656                         }
 657                 }
 658         }
 659         if (oidp->oid_refcnt > 1 ) {
 660                 oidp->oid_refcnt--;
 661         } else {
 662                 if (oidp->oid_refcnt == 0) {
 663                         printf("Warning: bad oid_refcnt=%u (%s)!\n",
 664                                 oidp->oid_refcnt, oidp->oid_name);
 665                         return (EINVAL);
 666                 }
 667                 sysctl_unregister_oid(oidp);
 668                 if (del) {
 669                         /*
 670                          * Wait for all threads running the handler to drain.
 671                          * This preserves the previous behavior when the
 672                          * sysctl lock was held across a handler invocation,
 673                          * and is necessary for module unload correctness.
 674                          */
 675                         while (oidp->oid_running > 0) {
 676                                 oidp->oid_kind |= CTLFLAG_DYING;
 677                                 SYSCTL_SLEEP(&oidp->oid_running, "oidrm", 0);
 678                         }
 679                         if (oidp->oid_descr)
 680                                 free(__DECONST(char *, oidp->oid_descr),
 681                                     M_SYSCTLOID);
 682                         if (oidp->oid_label)
 683                                 free(__DECONST(char *, oidp->oid_label),
 684                                     M_SYSCTLOID);
 685                         free(__DECONST(char *, oidp->oid_name), M_SYSCTLOID);
 686                         free(oidp, M_SYSCTLOID);
 687                 }
 688         }
 689         return (0);
 690 }
 691 /*
 692  * Create new sysctls at run time.
 693  * clist may point to a valid context initialized with sysctl_ctx_init().
 694  */
 695 struct sysctl_oid *
 696 sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
 697         int number, const char *name, int kind, void *arg1, intmax_t arg2,
 698         int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr,
 699         const char *label)
 700 {
 701         struct sysctl_oid *oidp;
 702
 703         /* You have to hook up somewhere.. */
 704         if (parent == NULL)
 705                 return(NULL);
 706         /* Check if the node already exists, otherwise create it */
 707         SYSCTL_WLOCK();
 708         oidp = sysctl_find_oidname(name, parent);
 709         if (oidp != NULL) {
 710                 if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 711                         oidp->oid_refcnt++;
 712                         /* Update the context */
 713                         if (clist != NULL)
 714                                 sysctl_ctx_entry_add(clist, oidp);
 715                         SYSCTL_WUNLOCK();
 716                         return (oidp);
 717                 } else {
 718                         SYSCTL_WUNLOCK();
 719                         printf("can't re-use a leaf (%s)!\n", name);
 720                         return (NULL);
 721                 }
 722         }
 723         oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
 724         oidp->oid_parent = parent;
 725         SLIST_INIT(&oidp->oid_children);
 726         oidp->oid_number = number;
 727         oidp->oid_refcnt = 1;
 728         oidp->oid_name = strdup(name, M_SYSCTLOID);
 729         oidp->oid_handler = handler;
 730         oidp->oid_kind = CTLFLAG_DYN | kind;
 731         oidp->oid_arg1 = arg1;
 732         oidp->oid_arg2 = arg2;
 733         oidp->oid_fmt = fmt;
 734         if (descr != NULL)
 735                 oidp->oid_descr = strdup(descr, M_SYSCTLOID);
 736         if (label != NULL)
 737                 oidp->oid_label = strdup(label, M_SYSCTLOID);
 738         /* Update the context, if used */
 739         if (clist != NULL)
 740                 sysctl_ctx_entry_add(clist, oidp);
 741         /* Register this oid */
 742         sysctl_register_oid(oidp);
 743         SYSCTL_WUNLOCK();
 744         return (oidp);
 745 }
 746
 747 /*
 748  * Rename an existing oid.
 749  */
 750 void
 751 sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
 752 {
 753         char *newname;
 754         char *oldname;
 755
 756         newname = strdup(name, M_SYSCTLOID);
 757         SYSCTL_WLOCK();
 758         oldname = __DECONST(char *, oidp->oid_name);
 759         oidp->oid_name = newname;
 760         SYSCTL_WUNLOCK();
 761         free(oldname, M_SYSCTLOID);
 762 }
 763
 764 /*
 765  * Reparent an existing oid.
 766  */
 767 int
 768 sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
 769 {
 770         struct sysctl_oid *oidp;
 771
 772         SYSCTL_WLOCK();
 773         if (oid->oid_parent == parent) {
 774                 SYSCTL_WUNLOCK();
 775                 return (0);
 776         }
 777         oidp = sysctl_find_oidname(oid->oid_name, parent);
 778         if (oidp != NULL) {
 779                 SYSCTL_WUNLOCK();
 780                 return (EEXIST);
 781         }
 782         sysctl_unregister_oid(oid);
 783         oid->oid_parent = parent;
 784         oid->oid_number = OID_AUTO;
 785         sysctl_register_oid(oid);
 786         SYSCTL_WUNLOCK();
 787         return (0);
 788 }
 789
 790 /*
 791  * Register the kernel's oids on startup.
 792  */
 793 SET_DECLARE(sysctl_set, struct sysctl_oid);
 794
 795 static void
 796 sysctl_register_all(void *arg)
 797 {
 798         struct sysctl_oid **oidp;
 799
 800         sx_init(&sysctlmemlock, "sysctl mem");
 801         SYSCTL_INIT();
 802         SYSCTL_WLOCK();
 803         SET_FOREACH(oidp, sysctl_set)
 804                 sysctl_register_oid(*oidp);
 805         SYSCTL_WUNLOCK();
 806 }
 807 SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, 0);
 808
 809 /*
 810  * "Staff-functions"
 811  *
 812  * These functions implement a presently undocumented interface
 813  * used by the sysctl program to walk the tree, and get the type
 814  * so it can print the value.
 815  * This interface is under work and consideration, and should probably
 816  * be killed with a big axe by the first person who can find the time.
 817  * (be aware though, that the proper interface isn't as obvious as it
 818  * may seem, there are various conflicting requirements.
 819  *
 820  * {0,0}        printf the entire MIB-tree.
 821  * {0,1,...}    return the name of the "..." OID.
 822  * {0,2,...}    return the next OID.
 823  * {0,3}        return the OID of the name in "new"
 824  * {0,4,...}    return the kind & format info for the "..." OID.
 825  * {0,5,...}    return the description of the "..." OID.
 826  * {0,6,...}    return the aggregation label of the "..." OID.
 827  */
 828
 829 #ifdef SYSCTL_DEBUG
 830 static void
 831 sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
 832 {
 833         int k;
 834         struct sysctl_oid *oidp;
 835
 836         SYSCTL_ASSERT_LOCKED();
 837         SLIST_FOREACH(oidp, l, oid_link) {
 838
 839                 for (k=0; k<i; k++)
 840                         printf(" ");
 841
 842                 printf("%d %s ", oidp->oid_number, oidp->oid_name);
 843
 844                 printf("%c%c",
 845                         oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
 846                         oidp->oid_kind & CTLFLAG_WR ? 'W':' ');
 847
 848                 if (oidp->oid_handler)
 849                         printf(" *Handler");
 850
 851                 switch (oidp->oid_kind & CTLTYPE) {
 852                         case CTLTYPE_NODE:
 853                                 printf(" Node\n");
 854                                 if (!oidp->oid_handler) {
 855                                         sysctl_sysctl_debug_dump_node(
 856                                             SYSCTL_CHILDREN(oidp), i + 2);
 857                                 }
 858                                 break;
 859                         case CTLTYPE_INT:    printf(" Int\n"); break;
 860                         case CTLTYPE_UINT:   printf(" u_int\n"); break;
 861                         case CTLTYPE_LONG:   printf(" Long\n"); break;
 862                         case CTLTYPE_ULONG:  printf(" u_long\n"); break;
 863                         case CTLTYPE_STRING: printf(" String\n"); break;
 864                         case CTLTYPE_S8:     printf(" int8_t\n"); break;
 865                         case CTLTYPE_S16:    printf(" int16_t\n"); break;
 866                         case CTLTYPE_S32:    printf(" int32_t\n"); break;
 867                         case CTLTYPE_S64:    printf(" int64_t\n"); break;
 868                         case CTLTYPE_U8:     printf(" uint8_t\n"); break;
 869                         case CTLTYPE_U16:    printf(" uint16_t\n"); break;
 870                         case CTLTYPE_U32:    printf(" uint32_t\n"); break;
 871                         case CTLTYPE_U64:    printf(" uint64_t\n"); break;
 872                         case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
 873                         default:             printf("\n");
 874                 }
 875
 876         }
 877 }
 878
 879 static int
 880 sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
 881 {
 882         struct rm_priotracker tracker;
 883         int error;
 884
 885         error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
 886         if (error)
 887                 return (error);
 888         SYSCTL_RLOCK(&tracker);
 889         sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
 890         SYSCTL_RUNLOCK(&tracker);
 891         return (ENOENT);
 892 }
 893
 894 SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
 895         0, 0, sysctl_sysctl_debug, "-", "");
 896 #endif
 897
 898 static int
 899 sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
 900 {
 901         int *name = (int *) arg1;
 902         u_int namelen = arg2;
 903         int error = 0;
 904         struct sysctl_oid *oid;
 905         struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
 906         struct rm_priotracker tracker;
 907         char buf[10];
 908
 909         SYSCTL_RLOCK(&tracker);
 910         while (namelen) {
 911                 if (!lsp) {
 912                         snprintf(buf,sizeof(buf),"%d",*name);
 913                         if (req->oldidx)
 914                                 error = SYSCTL_OUT(req, ".", 1);
 915                         if (!error)
 916                                 error = SYSCTL_OUT(req, buf, strlen(buf));
 917                         if (error)
 918                                 goto out;
 919                         namelen--;
 920                         name++;
 921                         continue;
 922                 }
 923                 lsp2 = NULL;
 924                 SLIST_FOREACH(oid, lsp, oid_link) {
 925                         if (oid->oid_number != *name)
 926                                 continue;
 927
 928                         if (req->oldidx)
 929                                 error = SYSCTL_OUT(req, ".", 1);
 930                         if (!error)
 931                                 error = SYSCTL_OUT(req, oid->oid_name,
 932                                         strlen(oid->oid_name));
 933                         if (error)
 934                                 goto out;
 935
 936                         namelen--;
 937                         name++;
 938
 939                         if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 940                                 break;
 941
 942                         if (oid->oid_handler)
 943                                 break;
 944
 945                         lsp2 = SYSCTL_CHILDREN(oid);
 946                         break;
 947                 }
 948                 lsp = lsp2;
 949         }
 950         error = SYSCTL_OUT(req, "", 1);
 951  out:
 952         SYSCTL_RUNLOCK(&tracker);
 953         return (error);
 954 }
 955
 956 /*
 957  * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
 958  * capability mode.
 959  */
 960 static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
 961     sysctl_sysctl_name, "");
 962
 963 static int
 964 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen,
 965         int *next, int *len, int level, struct sysctl_oid **oidpp)
 966 {
 967         struct sysctl_oid *oidp;
 968
 969         SYSCTL_ASSERT_LOCKED();
 970         *len = level;
 971         SLIST_FOREACH(oidp, lsp, oid_link) {
 972                 *next = oidp->oid_number;
 973                 *oidpp = oidp;
 974
 975                 if (oidp->oid_kind & CTLFLAG_SKIP)
 976                         continue;
 977
 978                 if (!namelen) {
 979                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 980                                 return (0);
 981                         if (oidp->oid_handler)
 982                                 /* We really should call the handler here...*/
 983                                 return (0);
 984                         lsp = SYSCTL_CHILDREN(oidp);
 985                         if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1,
 986                                 len, level+1, oidpp))
 987                                 return (0);
 988                         goto emptynode;
 989                 }
 990
 991                 if (oidp->oid_number < *name)
 992                         continue;
 993
 994                 if (oidp->oid_number > *name) {
 995                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 996                                 return (0);
 997                         if (oidp->oid_handler)
 998                                 return (0);
 999                         lsp = SYSCTL_CHILDREN(oidp);
1000                         if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1,
1001                                 next+1, len, level+1, oidpp))
1002                                 return (0);
1003                         goto next;
1004                 }
1005                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
1006                         continue;
1007
1008                 if (oidp->oid_handler)
1009                         continue;
1010
1011                 lsp = SYSCTL_CHILDREN(oidp);
1012                 if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1,
1013                         len, level+1, oidpp))
1014                         return (0);
1015         next:
1016                 namelen = 1;
1017         emptynode:
1018                 *len = level;
1019         }
1020         return (1);
1021 }
1022
1023 static int
1024 sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
1025 {
1026         int *name = (int *) arg1;
1027         u_int namelen = arg2;
1028         int i, j, error;
1029         struct sysctl_oid *oid;
1030         struct sysctl_oid_list *lsp = &sysctl__children;
1031         struct rm_priotracker tracker;
1032         int newoid[CTL_MAXNAME];
1033
1034         SYSCTL_RLOCK(&tracker);
1035         i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
1036         SYSCTL_RUNLOCK(&tracker);
1037         if (i)
1038                 return (ENOENT);
1039         error = SYSCTL_OUT(req, newoid, j * sizeof (int));
1040         return (error);
1041 }
1042
1043 /*
1044  * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
1045  * capability mode.
1046  */
1047 static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
1048     sysctl_sysctl_next, "");
1049
1050 static int
1051 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
1052 {
1053         struct sysctl_oid *oidp;
1054         struct sysctl_oid_list *lsp = &sysctl__children;
1055         char *p;
1056
1057         SYSCTL_ASSERT_LOCKED();
1058
1059         for (*len = 0; *len < CTL_MAXNAME;) {
1060                 p = strsep(&name, ".");
1061
1062                 oidp = SLIST_FIRST(lsp);
1063                 for (;; oidp = SLIST_NEXT(oidp, oid_link)) {
1064                         if (oidp == NULL)
1065                                 return (ENOENT);
1066                         if (strcmp(p, oidp->oid_name) == 0)
1067                                 break;
1068                 }
1069                 *oid++ = oidp->oid_number;
1070                 (*len)++;
1071
1072                 if (name == NULL || *name == '\0') {
1073                         if (oidpp)
1074                                 *oidpp = oidp;
1075                         return (0);
1076                 }
1077
1078                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
1079                         break;
1080
1081                 if (oidp->oid_handler)
1082                         break;
1083
1084                 lsp = SYSCTL_CHILDREN(oidp);
1085         }
1086         return (ENOENT);
1087 }
1088
1089 static int
1090 sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
1091 {
1092         char *p;
1093         int error, oid[CTL_MAXNAME], len = 0;
1094         struct sysctl_oid *op = NULL;
1095         struct rm_priotracker tracker;
1096
1097         if (!req->newlen)
1098                 return (ENOENT);
1099         if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
1100                 return (ENAMETOOLONG);
1101
1102         p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
1103
1104         error = SYSCTL_IN(req, p, req->newlen);
1105         if (error) {
1106                 free(p, M_SYSCTL);
1107                 return (error);
1108         }
1109
1110         p [req->newlen] = '\0';
1111
1112         SYSCTL_RLOCK(&tracker);
1113         error = name2oid(p, oid, &len, &op);
1114         SYSCTL_RUNLOCK(&tracker);
1115
1116         free(p, M_SYSCTL);
1117
1118         if (error)
1119                 return (error);
1120
1121         error = SYSCTL_OUT(req, oid, len * sizeof *oid);
1122         return (error);
1123 }
1124
1125 /*
1126  * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
1127  * capability mode.
1128  */
1129 SYSCTL_PROC(_sysctl, 3, name2oid,
1130     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE
1131     | CTLFLAG_CAPRW, 0, 0, sysctl_sysctl_name2oid, "I", "");
1132
1133 static int
1134 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
1135 {
1136         struct sysctl_oid *oid;
1137         struct rm_priotracker tracker;
1138         int error;
1139
1140         SYSCTL_RLOCK(&tracker);
1141         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
1142         if (error)
1143                 goto out;
1144
1145         if (oid->oid_fmt == NULL) {
1146                 error = ENOENT;
1147                 goto out;
1148         }
1149         error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
1150         if (error)
1151                 goto out;
1152         error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
1153  out:
1154         SYSCTL_RUNLOCK(&tracker);
1155         return (error);
1156 }
1157
1158
1159 static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
1160     sysctl_sysctl_oidfmt, "");
1161
1162 static int
1163 sysctl_sysctl_oiddescr(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_descr == NULL) {
1175                 error = ENOENT;
1176                 goto out;
1177         }
1178         error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
1179  out:
1180         SYSCTL_RUNLOCK(&tracker);
1181         return (error);
1182 }
1183
1184 static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
1185     sysctl_sysctl_oiddescr, "");
1186
1187 static int
1188 sysctl_sysctl_oidlabel(SYSCTL_HANDLER_ARGS)
1189 {
1190         struct sysctl_oid *oid;
1191         struct rm_priotracker tracker;
1192         int error;
1193
1194         SYSCTL_RLOCK(&tracker);
1195         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
1196         if (error)
1197                 goto out;
1198
1199         if (oid->oid_label == NULL) {
1200                 error = ENOENT;
1201                 goto out;
1202         }
1203         error = SYSCTL_OUT(req, oid->oid_label, strlen(oid->oid_label) + 1);
1204  out:
1205         SYSCTL_RUNLOCK(&tracker);
1206         return (error);
1207 }
1208
1209 static SYSCTL_NODE(_sysctl, 6, oidlabel,
1210     CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidlabel, "");
1211
1212 /*
1213  * Default "handler" functions.
1214  */
1215
1216 /*
1217  * Handle a bool.
1218  * Two cases:
1219  *     a variable:  point arg1 at it.
1220  *     a constant:  pass it in arg2.
1221  */
1222
1223 int
1224 sysctl_handle_bool(SYSCTL_HANDLER_ARGS)
1225 {
1226         uint8_t temp;
1227         int error;
1228
1229         /*
1230          * Attempt to get a coherent snapshot by making a copy of the data.
1231          */
1232         if (arg1)
1233                 temp = *(bool *)arg1 ? 1 : 0;
1234         else
1235                 temp = arg2 ? 1 : 0;
1236
1237         error = SYSCTL_OUT(req, &temp, sizeof(temp));
1238         if (error || !req->newptr)
1239                 return (error);
1240
1241         if (!arg1)
1242                 error = EPERM;
1243         else {
1244                 error = SYSCTL_IN(req, &temp, sizeof(temp));
1245                 if (!error)
1246                         *(bool *)arg1 = temp ? 1 : 0;
1247         }
1248         return (error);
1249 }
1250
1251 /*
1252  * Handle an int8_t, signed or unsigned.
1253  * Two cases:
1254  *     a variable:  point arg1 at it.
1255  *     a constant:  pass it in arg2.
1256  */
1257
1258 int
1259 sysctl_handle_8(SYSCTL_HANDLER_ARGS)
1260 {
1261         int8_t tmpout;
1262         int error = 0;
1263
1264         /*
1265          * Attempt to get a coherent snapshot by making a copy of the data.
1266          */
1267         if (arg1)
1268                 tmpout = *(int8_t *)arg1;
1269         else
1270                 tmpout = arg2;
1271         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1272
1273         if (error || !req->newptr)
1274                 return (error);
1275
1276         if (!arg1)
1277                 error = EPERM;
1278         else
1279                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1280         return (error);
1281 }
1282
1283 /*
1284  * Handle an int16_t, signed or unsigned.
1285  * Two cases:
1286  *     a variable:  point arg1 at it.
1287  *     a constant:  pass it in arg2.
1288  */
1289
1290 int
1291 sysctl_handle_16(SYSCTL_HANDLER_ARGS)
1292 {
1293         int16_t tmpout;
1294         int error = 0;
1295
1296         /*
1297          * Attempt to get a coherent snapshot by making a copy of the data.
1298          */
1299         if (arg1)
1300                 tmpout = *(int16_t *)arg1;
1301         else
1302                 tmpout = arg2;
1303         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1304
1305         if (error || !req->newptr)
1306                 return (error);
1307
1308         if (!arg1)
1309                 error = EPERM;
1310         else
1311                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1312         return (error);
1313 }
1314
1315 /*
1316  * Handle an int32_t, signed or unsigned.
1317  * Two cases:
1318  *     a variable:  point arg1 at it.
1319  *     a constant:  pass it in arg2.
1320  */
1321
1322 int
1323 sysctl_handle_32(SYSCTL_HANDLER_ARGS)
1324 {
1325         int32_t tmpout;
1326         int error = 0;
1327
1328         /*
1329          * Attempt to get a coherent snapshot by making a copy of the data.
1330          */
1331         if (arg1)
1332                 tmpout = *(int32_t *)arg1;
1333         else
1334                 tmpout = arg2;
1335         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1336
1337         if (error || !req->newptr)
1338                 return (error);
1339
1340         if (!arg1)
1341                 error = EPERM;
1342         else
1343                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1344         return (error);
1345 }
1346
1347 /*
1348  * Handle an int, signed or unsigned.
1349  * Two cases:
1350  *     a variable:  point arg1 at it.
1351  *     a constant:  pass it in arg2.
1352  */
1353
1354 int
1355 sysctl_handle_int(SYSCTL_HANDLER_ARGS)
1356 {
1357         int tmpout, error = 0;
1358
1359         /*
1360          * Attempt to get a coherent snapshot by making a copy of the data.
1361          */
1362         if (arg1)
1363                 tmpout = *(int *)arg1;
1364         else
1365                 tmpout = arg2;
1366         error = SYSCTL_OUT(req, &tmpout, sizeof(int));
1367
1368         if (error || !req->newptr)
1369                 return (error);
1370
1371         if (!arg1)
1372                 error = EPERM;
1373         else
1374                 error = SYSCTL_IN(req, arg1, sizeof(int));
1375         return (error);
1376 }
1377
1378 /*
1379  * Based on on sysctl_handle_int() convert milliseconds into ticks.
1380  * Note: this is used by TCP.
1381  */
1382
1383 int
1384 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
1385 {
1386         int error, s, tt;
1387
1388         tt = *(int *)arg1;
1389         s = (int)((int64_t)tt * 1000 / hz);
1390
1391         error = sysctl_handle_int(oidp, &s, 0, req);
1392         if (error || !req->newptr)
1393                 return (error);
1394
1395         tt = (int)((int64_t)s * hz / 1000);
1396         if (tt < 1)
1397                 return (EINVAL);
1398
1399         *(int *)arg1 = tt;
1400         return (0);
1401 }
1402
1403
1404 /*
1405  * Handle a long, signed or unsigned.
1406  * Two cases:
1407  *     a variable:  point arg1 at it.
1408  *     a constant:  pass it in arg2.
1409  */
1410
1411 int
1412 sysctl_handle_long(SYSCTL_HANDLER_ARGS)
1413 {
1414         int error = 0;
1415         long tmplong;
1416 #ifdef SCTL_MASK32
1417         int tmpint;
1418 #endif
1419
1420         /*
1421          * Attempt to get a coherent snapshot by making a copy of the data.
1422          */
1423         if (arg1)
1424                 tmplong = *(long *)arg1;
1425         else
1426                 tmplong = arg2;
1427 #ifdef SCTL_MASK32
1428         if (req->flags & SCTL_MASK32) {
1429                 tmpint = tmplong;
1430                 error = SYSCTL_OUT(req, &tmpint, sizeof(int));
1431         } else
1432 #endif
1433                 error = SYSCTL_OUT(req, &tmplong, sizeof(long));
1434
1435         if (error || !req->newptr)
1436                 return (error);
1437
1438         if (!arg1)
1439                 error = EPERM;
1440 #ifdef SCTL_MASK32
1441         else if (req->flags & SCTL_MASK32) {
1442                 error = SYSCTL_IN(req, &tmpint, sizeof(int));
1443                 *(long *)arg1 = (long)tmpint;
1444         }
1445 #endif
1446         else
1447                 error = SYSCTL_IN(req, arg1, sizeof(long));
1448         return (error);
1449 }
1450
1451 /*
1452  * Handle a 64 bit int, signed or unsigned.
1453  * Two cases:
1454  *     a variable:  point arg1 at it.
1455  *     a constant:  pass it in arg2.
1456  */
1457 int
1458 sysctl_handle_64(SYSCTL_HANDLER_ARGS)
1459 {
1460         int error = 0;
1461         uint64_t tmpout;
1462
1463         /*
1464          * Attempt to get a coherent snapshot by making a copy of the data.
1465          */
1466         if (arg1)
1467                 tmpout = *(uint64_t *)arg1;
1468         else
1469                 tmpout = arg2;
1470         error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));
1471
1472         if (error || !req->newptr)
1473                 return (error);
1474
1475         if (!arg1)
1476                 error = EPERM;
1477         else
1478                 error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
1479         return (error);
1480 }
1481
1482 /*
1483  * Handle our generic '\0' terminated 'C' string.
1484  * Two cases:
1485  *      a variable string:  point arg1 at it, arg2 is max length.
1486  *      a constant string:  point arg1 at it, arg2 is zero.
1487  */
1488
1489 int
1490 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
1491 {
1492         size_t outlen;
1493         int error = 0, ro_string = 0;
1494
1495         /*
1496          * A zero-length buffer indicates a fixed size read-only
1497          * string:
1498          */
1499         if (arg2 == 0) {
1500                 arg2 = strlen((char *)arg1) + 1;
1501                 ro_string = 1;
1502         }
1503
1504         if (req->oldptr != NULL) {
1505                 char *tmparg;
1506
1507                 if (ro_string) {
1508                         tmparg = arg1;
1509                 } else {
1510                         /* try to make a coherent snapshot of the string */
1511                         tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);
1512                         memcpy(tmparg, arg1, arg2);
1513                 }
1514
1515                 outlen = strnlen(tmparg, arg2 - 1) + 1;
1516                 error = SYSCTL_OUT(req, tmparg, outlen);
1517
1518                 if (!ro_string)
1519                         free(tmparg, M_SYSCTLTMP);
1520         } else {
1521                 outlen = strnlen((char *)arg1, arg2 - 1) + 1;
1522                 error = SYSCTL_OUT(req, NULL, outlen);
1523         }
1524         if (error || !req->newptr)
1525                 return (error);
1526
1527         if ((req->newlen - req->newidx) >= arg2) {
1528                 error = EINVAL;
1529         } else {
1530                 arg2 = (req->newlen - req->newidx);
1531                 error = SYSCTL_IN(req, arg1, arg2);
1532                 ((char *)arg1)[arg2] = '\0';
1533         }
1534         return (error);
1535 }
1536
1537 /*
1538  * Handle any kind of opaque data.
1539  * arg1 points to it, arg2 is the size.
1540  */
1541
1542 int
1543 sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
1544 {
1545         int error, tries;
1546         u_int generation;
1547         struct sysctl_req req2;
1548
1549         /*
1550          * Attempt to get a coherent snapshot, by using the thread
1551          * pre-emption counter updated from within mi_switch() to
1552          * determine if we were pre-empted during a bcopy() or
1553          * copyout(). Make 3 attempts at doing this before giving up.
1554          * If we encounter an error, stop immediately.
1555          */
1556         tries = 0;
1557         req2 = *req;
1558 retry:
1559         generation = curthread->td_generation;
1560         error = SYSCTL_OUT(req, arg1, arg2);
1561         if (error)
1562                 return (error);
1563         tries++;
1564         if (generation != curthread->td_generation && tries < 3) {
1565                 *req = req2;
1566                 goto retry;
1567         }
1568
1569         error = SYSCTL_IN(req, arg1, arg2);
1570
1571         return (error);
1572 }
1573
1574 /*
1575  * Transfer functions to/from kernel space.
1576  * XXX: rather untested at this point
1577  */
1578 static int
1579 sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
1580 {
1581         size_t i = 0;
1582
1583         if (req->oldptr) {
1584                 i = l;
1585                 if (req->oldlen <= req->oldidx)
1586                         i = 0;
1587                 else
1588                         if (i > req->oldlen - req->oldidx)
1589                                 i = req->oldlen - req->oldidx;
1590                 if (i > 0)
1591                         bcopy(p, (char *)req->oldptr + req->oldidx, i);
1592         }
1593         req->oldidx += l;
1594         if (req->oldptr && i != l)
1595                 return (ENOMEM);
1596         return (0);
1597 }
1598
1599 static int
1600 sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
1601 {
1602         if (!req->newptr)
1603                 return (0);
1604         if (req->newlen - req->newidx < l)
1605                 return (EINVAL);
1606         bcopy((char *)req->newptr + req->newidx, p, l);
1607         req->newidx += l;
1608         return (0);
1609 }
1610
1611 int
1612 kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
1613     size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
1614 {
1615         int error = 0;
1616         struct sysctl_req req;
1617
1618         bzero(&req, sizeof req);
1619
1620         req.td = td;
1621         req.flags = flags;
1622
1623         if (oldlenp) {
1624                 req.oldlen = *oldlenp;
1625         }
1626         req.validlen = req.oldlen;
1627
1628         if (old) {
1629                 req.oldptr= old;
1630         }
1631
1632         if (new != NULL) {
1633                 req.newlen = newlen;
1634                 req.newptr = new;
1635         }
1636
1637         req.oldfunc = sysctl_old_kernel;
1638         req.newfunc = sysctl_new_kernel;
1639         req.lock = REQ_UNWIRED;
1640
1641         error = sysctl_root(0, name, namelen, &req);
1642
1643         if (req.lock == REQ_WIRED && req.validlen > 0)
1644                 vsunlock(req.oldptr, req.validlen);
1645
1646         if (error && error != ENOMEM)
1647                 return (error);
1648
1649         if (retval) {
1650                 if (req.oldptr && req.oldidx > req.validlen)
1651                         *retval = req.validlen;
1652                 else
1653                         *retval = req.oldidx;
1654         }
1655         return (error);
1656 }
1657
1658 int
1659 kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
1660     void *new, size_t newlen, size_t *retval, int flags)
1661 {
1662         int oid[CTL_MAXNAME];
1663         size_t oidlen, plen;
1664         int error;
1665
1666         oid[0] = 0;             /* sysctl internal magic */
1667         oid[1] = 3;             /* name2oid */
1668         oidlen = sizeof(oid);
1669
1670         error = kernel_sysctl(td, oid, 2, oid, &oidlen,
1671             (void *)name, strlen(name), &plen, flags);
1672         if (error)
1673                 return (error);
1674
1675         error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
1676             new, newlen, retval, flags);
1677         return (error);
1678 }
1679
1680 /*
1681  * Transfer function to/from user space.
1682  */
1683 static int
1684 sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
1685 {
1686         size_t i, len, origidx;
1687         int error;
1688
1689         origidx = req->oldidx;
1690         req->oldidx += l;
1691         if (req->oldptr == NULL)
1692                 return (0);
1693         /*
1694          * If we have not wired the user supplied buffer and we are currently
1695          * holding locks, drop a witness warning, as it's possible that
1696          * write operations to the user page can sleep.
1697          */
1698         if (req->lock != REQ_WIRED)
1699                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
1700                     "sysctl_old_user()");
1701         i = l;
1702         len = req->validlen;
1703         if (len <= origidx)
1704                 i = 0;
1705         else {
1706                 if (i > len - origidx)
1707                         i = len - origidx;
1708                 if (req->lock == REQ_WIRED) {
1709                         error = copyout_nofault(p, (char *)req->oldptr +
1710                             origidx, i);
1711                 } else
1712                         error = copyout(p, (char *)req->oldptr + origidx, i);
1713                 if (error != 0)
1714                         return (error);
1715         }
1716         if (i < l)
1717                 return (ENOMEM);
1718         return (0);
1719 }
1720
1721 static int
1722 sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
1723 {
1724         int error;
1725
1726         if (!req->newptr)
1727                 return (0);
1728         if (req->newlen - req->newidx < l)
1729                 return (EINVAL);
1730         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
1731             "sysctl_new_user()");
1732         error = copyin((char *)req->newptr + req->newidx, p, l);
1733         req->newidx += l;
1734         return (error);
1735 }
1736
1737 /*
1738  * Wire the user space destination buffer.  If set to a value greater than
1739  * zero, the len parameter limits the maximum amount of wired memory.
1740  */
1741 int
1742 sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
1743 {
1744         int ret;
1745         size_t wiredlen;
1746
1747         wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
1748         ret = 0;
1749         if (req->lock != REQ_WIRED && req->oldptr &&
1750             req->oldfunc == sysctl_old_user) {
1751                 if (wiredlen != 0) {
1752                         ret = vslock(req->oldptr, wiredlen);
1753                         if (ret != 0) {
1754                                 if (ret != ENOMEM)
1755                                         return (ret);
1756                                 wiredlen = 0;
1757                         }
1758                 }
1759                 req->lock = REQ_WIRED;
1760                 req->validlen = wiredlen;
1761         }
1762         return (0);
1763 }
1764
1765 int
1766 sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
1767     int *nindx, struct sysctl_req *req)
1768 {
1769         struct sysctl_oid_list *lsp;
1770         struct sysctl_oid *oid;
1771         int indx;
1772
1773         SYSCTL_ASSERT_LOCKED();
1774         lsp = &sysctl__children;
1775         indx = 0;
1776         while (indx < CTL_MAXNAME) {
1777                 SLIST_FOREACH(oid, lsp, oid_link) {
1778                         if (oid->oid_number == name[indx])
1779                                 break;
1780                 }
1781                 if (oid == NULL)
1782                         return (ENOENT);
1783
1784                 indx++;
1785                 if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1786                         if (oid->oid_handler != NULL || indx == namelen) {
1787                                 *noid = oid;
1788                                 if (nindx != NULL)
1789                                         *nindx = indx;
1790                                 KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
1791                                     ("%s found DYING node %p", __func__, oid));
1792                                 return (0);
1793                         }
1794                         lsp = SYSCTL_CHILDREN(oid);
1795                 } else if (indx == namelen) {
1796                         *noid = oid;
1797                         if (nindx != NULL)
1798                                 *nindx = indx;
1799                         KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
1800                             ("%s found DYING node %p", __func__, oid));
1801                         return (0);
1802                 } else {
1803                         return (ENOTDIR);
1804                 }
1805         }
1806         return (ENOENT);
1807 }
1808
1809 /*
1810  * Traverse our tree, and find the right node, execute whatever it points
1811  * to, and return the resulting error code.
1812  */
1813
1814 static int
1815 sysctl_root(SYSCTL_HANDLER_ARGS)
1816 {
1817         struct sysctl_oid *oid;
1818         struct rm_priotracker tracker;
1819         int error, indx, lvl;
1820
1821         SYSCTL_RLOCK(&tracker);
1822
1823         error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
1824         if (error)
1825                 goto out;
1826
1827         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1828                 /*
1829                  * You can't call a sysctl when it's a node, but has
1830                  * no handler.  Inform the user that it's a node.
1831                  * The indx may or may not be the same as namelen.
1832                  */
1833                 if (oid->oid_handler == NULL) {
1834                         error = EISDIR;
1835                         goto out;
1836                 }
1837         }
1838
1839         /* Is this sysctl writable? */
1840         if (req->newptr && !(oid->oid_kind & CTLFLAG_WR)) {
1841                 error = EPERM;
1842                 goto out;
1843         }
1844
1845         KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));
1846
1847 #ifdef CAPABILITY_MODE
1848         /*
1849          * If the process is in capability mode, then don't permit reading or
1850          * writing unless specifically granted for the node.
1851          */
1852         if (IN_CAPABILITY_MODE(req->td)) {
1853                 if ((req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD)) ||
1854                     (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))) {
1855                         error = EPERM;
1856                         goto out;
1857                 }
1858         }
1859 #endif
1860
1861         /* Is this sysctl sensitive to securelevels? */
1862         if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
1863                 lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
1864                 error = securelevel_gt(req->td->td_ucred, lvl);
1865                 if (error)
1866                         goto out;
1867         }
1868
1869         /* Is this sysctl writable by only privileged users? */
1870         if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
1871                 int priv;
1872
1873                 if (oid->oid_kind & CTLFLAG_PRISON)
1874                         priv = PRIV_SYSCTL_WRITEJAIL;
1875 #ifdef VIMAGE
1876                 else if ((oid->oid_kind & CTLFLAG_VNET) &&
1877                      prison_owns_vnet(req->td->td_ucred))
1878                         priv = PRIV_SYSCTL_WRITEJAIL;
1879 #endif
1880                 else
1881                         priv = PRIV_SYSCTL_WRITE;
1882                 error = priv_check(req->td, priv);
1883                 if (error)
1884                         goto out;
1885         }
1886
1887         if (!oid->oid_handler) {
1888                 error = EINVAL;
1889                 goto out;
1890         }
1891
1892         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1893                 arg1 = (int *)arg1 + indx;
1894                 arg2 -= indx;
1895         } else {
1896                 arg1 = oid->oid_arg1;
1897                 arg2 = oid->oid_arg2;
1898         }
1899 #ifdef MAC
1900         error = mac_system_check_sysctl(req->td->td_ucred, oid, arg1, arg2,
1901             req);
1902         if (error != 0)
1903                 goto out;
1904 #endif
1905 #ifdef VIMAGE
1906         if ((oid->oid_kind & CTLFLAG_VNET) && arg1 != NULL)
1907                 arg1 = (void *)(curvnet->vnet_data_base + (uintptr_t)arg1);
1908 #endif
1909         error = sysctl_root_handler_locked(oid, arg1, arg2, req, &tracker);
1910
1911 out:
1912         SYSCTL_RUNLOCK(&tracker);
1913         return (error);
1914 }
1915
1916 #ifndef _SYS_SYSPROTO_H_
1917 struct sysctl_args {
1918         int     *name;
1919         u_int   namelen;
1920         void    *old;
1921         size_t  *oldlenp;
1922         void    *new;
1923         size_t  newlen;
1924 };
1925 #endif
1926 int
1927 sys___sysctl(struct thread *td, struct sysctl_args *uap)
1928 {
1929         int error, i, name[CTL_MAXNAME];
1930         size_t j;
1931
1932         if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
1933                 return (EINVAL);
1934
1935         error = copyin(uap->name, &name, uap->namelen * sizeof(int));
1936         if (error)
1937                 return (error);
1938
1939         error = userland_sysctl(td, name, uap->namelen,
1940                 uap->old, uap->oldlenp, 0,
1941                 uap->new, uap->newlen, &j, 0);
1942         if (error && error != ENOMEM)
1943                 return (error);
1944         if (uap->oldlenp) {
1945                 i = copyout(&j, uap->oldlenp, sizeof(j));
1946                 if (i)
1947                         return (i);
1948         }
1949         return (error);
1950 }
1951
1952 /*
1953  * This is used from various compatibility syscalls too.  That's why name
1954  * must be in kernel space.
1955  */
1956 int
1957 userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
1958     size_t *oldlenp, int inkernel, void *new, size_t newlen, size_t *retval,
1959     int flags)
1960 {
1961         int error = 0, memlocked;
1962         struct sysctl_req req;
1963
1964         bzero(&req, sizeof req);
1965
1966         req.td = td;
1967         req.flags = flags;
1968
1969         if (oldlenp) {
1970                 if (inkernel) {
1971                         req.oldlen = *oldlenp;
1972                 } else {
1973                         error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
1974                         if (error)
1975                                 return (error);
1976                 }
1977         }
1978         req.validlen = req.oldlen;
1979
1980         if (old) {
1981                 if (!useracc(old, req.oldlen, VM_PROT_WRITE))
1982                         return (EFAULT);
1983                 req.oldptr= old;
1984         }
1985
1986         if (new != NULL) {
1987                 if (!useracc(new, newlen, VM_PROT_READ))
1988                         return (EFAULT);
1989                 req.newlen = newlen;
1990                 req.newptr = new;
1991         }
1992
1993         req.oldfunc = sysctl_old_user;
1994         req.newfunc = sysctl_new_user;
1995         req.lock = REQ_UNWIRED;
1996
1997 #ifdef KTRACE
1998         if (KTRPOINT(curthread, KTR_SYSCTL))
1999                 ktrsysctl(name, namelen);
2000 #endif
2001
2002         if (req.oldptr && req.oldlen > PAGE_SIZE) {
2003                 memlocked = 1;
2004                 sx_xlock(&sysctlmemlock);
2005         } else
2006                 memlocked = 0;
2007         CURVNET_SET(TD_TO_VNET(td));
2008
2009         for (;;) {
2010                 req.oldidx = 0;
2011                 req.newidx = 0;
2012                 error = sysctl_root(0, name, namelen, &req);
2013                 if (error != EAGAIN)
2014                         break;
2015                 kern_yield(PRI_USER);
2016         }
2017
2018         CURVNET_RESTORE();
2019
2020         if (req.lock == REQ_WIRED && req.validlen > 0)
2021                 vsunlock(req.oldptr, req.validlen);
2022         if (memlocked)
2023                 sx_xunlock(&sysctlmemlock);
2024
2025         if (error && error != ENOMEM)
2026                 return (error);
2027
2028         if (retval) {
2029                 if (req.oldptr && req.oldidx > req.validlen)
2030                         *retval = req.validlen;
2031                 else
2032                         *retval = req.oldidx;
2033         }
2034         return (error);
2035 }
2036
2037 /*
2038  * Drain into a sysctl struct.  The user buffer should be wired if a page
2039  * fault would cause issue.
2040  */
2041 static int
2042 sbuf_sysctl_drain(void *arg, const char *data, int len)
2043 {
2044         struct sysctl_req *req = arg;
2045         int error;
2046
2047         error = SYSCTL_OUT(req, data, len);
2048         KASSERT(error >= 0, ("Got unexpected negative value %d", error));
2049         return (error == 0 ? len : -error);
2050 }
2051
2052 struct sbuf *
2053 sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length,
2054     struct sysctl_req *req)
2055 {
2056
2057         /* Supply a default buffer size if none given. */
2058         if (buf == NULL && length == 0)
2059                 length = 64;
2060         s = sbuf_new(s, buf, length, SBUF_FIXEDLEN | SBUF_INCLUDENUL);
2061         sbuf_set_drain(s, sbuf_sysctl_drain, req);
2062         return (s);
2063 }