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("can't remove non-dynamic nodes!\n");
 632                 return (EINVAL);
 633         }
 634         /*
 635          * WARNING: normal method to do this should be through
 636          * sysctl_ctx_free(). Use recursing as the last resort
 637          * method to purge your sysctl tree of leftovers...
 638          * However, if some other code still references these nodes,
 639          * it will panic.
 640          */
 641         if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 642                 if (oidp->oid_refcnt == 1) {
 643                         SLIST_FOREACH_SAFE(p,
 644                             SYSCTL_CHILDREN(oidp), oid_link, tmp) {
 645                                 if (!recurse) {
 646                                         printf("Warning: failed attempt to "
 647                                             "remove oid %s with child %s\n",
 648                                             oidp->oid_name, p->oid_name);
 649                                         return (ENOTEMPTY);
 650                                 }
 651                                 error = sysctl_remove_oid_locked(p, del,
 652                                     recurse);
 653                                 if (error)
 654                                         return (error);
 655                         }
 656                 }
 657         }
 658         if (oidp->oid_refcnt > 1 ) {
 659                 oidp->oid_refcnt--;
 660         } else {
 661                 if (oidp->oid_refcnt == 0) {
 662                         printf("Warning: bad oid_refcnt=%u (%s)!\n",
 663                                 oidp->oid_refcnt, oidp->oid_name);
 664                         return (EINVAL);
 665                 }
 666                 sysctl_unregister_oid(oidp);
 667                 if (del) {
 668                         /*
 669                          * Wait for all threads running the handler to drain.
 670                          * This preserves the previous behavior when the
 671                          * sysctl lock was held across a handler invocation,
 672                          * and is necessary for module unload correctness.
 673                          */
 674                         while (oidp->oid_running > 0) {
 675                                 oidp->oid_kind |= CTLFLAG_DYING;
 676                                 SYSCTL_SLEEP(&oidp->oid_running, "oidrm", 0);
 677                         }
 678                         if (oidp->oid_descr)
 679                                 free(__DECONST(char *, oidp->oid_descr),
 680                                     M_SYSCTLOID);
 681                         if (oidp->oid_label)
 682                                 free(__DECONST(char *, oidp->oid_label),
 683                                     M_SYSCTLOID);
 684                         free(__DECONST(char *, oidp->oid_name), M_SYSCTLOID);
 685                         free(oidp, M_SYSCTLOID);
 686                 }
 687         }
 688         return (0);
 689 }
 690 /*
 691  * Create new sysctls at run time.
 692  * clist may point to a valid context initialized with sysctl_ctx_init().
 693  */
 694 struct sysctl_oid *
 695 sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
 696         int number, const char *name, int kind, void *arg1, intmax_t arg2,
 697         int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr,
 698         const char *label)
 699 {
 700         struct sysctl_oid *oidp;
 701
 702         /* You have to hook up somewhere.. */
 703         if (parent == NULL)
 704                 return(NULL);
 705         /* Check if the node already exists, otherwise create it */
 706         SYSCTL_WLOCK();
 707         oidp = sysctl_find_oidname(name, parent);
 708         if (oidp != NULL) {
 709                 if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
 710                         oidp->oid_refcnt++;
 711                         /* Update the context */
 712                         if (clist != NULL)
 713                                 sysctl_ctx_entry_add(clist, oidp);
 714                         SYSCTL_WUNLOCK();
 715                         return (oidp);
 716                 } else {
 717                         SYSCTL_WUNLOCK();
 718                         printf("can't re-use a leaf (%s)!\n", name);
 719                         return (NULL);
 720                 }
 721         }
 722         oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
 723         oidp->oid_parent = parent;
 724         SLIST_INIT(&oidp->oid_children);
 725         oidp->oid_number = number;
 726         oidp->oid_refcnt = 1;
 727         oidp->oid_name = strdup(name, M_SYSCTLOID);
 728         oidp->oid_handler = handler;
 729         oidp->oid_kind = CTLFLAG_DYN | kind;
 730         oidp->oid_arg1 = arg1;
 731         oidp->oid_arg2 = arg2;
 732         oidp->oid_fmt = fmt;
 733         if (descr != NULL)
 734                 oidp->oid_descr = strdup(descr, M_SYSCTLOID);
 735         if (label != NULL)
 736                 oidp->oid_label = strdup(label, M_SYSCTLOID);
 737         /* Update the context, if used */
 738         if (clist != NULL)
 739                 sysctl_ctx_entry_add(clist, oidp);
 740         /* Register this oid */
 741         sysctl_register_oid(oidp);
 742         SYSCTL_WUNLOCK();
 743         return (oidp);
 744 }
 745
 746 /*
 747  * Rename an existing oid.
 748  */
 749 void
 750 sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
 751 {
 752         char *newname;
 753         char *oldname;
 754
 755         newname = strdup(name, M_SYSCTLOID);
 756         SYSCTL_WLOCK();
 757         oldname = __DECONST(char *, oidp->oid_name);
 758         oidp->oid_name = newname;
 759         SYSCTL_WUNLOCK();
 760         free(oldname, M_SYSCTLOID);
 761 }
 762
 763 /*
 764  * Reparent an existing oid.
 765  */
 766 int
 767 sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
 768 {
 769         struct sysctl_oid *oidp;
 770
 771         SYSCTL_WLOCK();
 772         if (oid->oid_parent == parent) {
 773                 SYSCTL_WUNLOCK();
 774                 return (0);
 775         }
 776         oidp = sysctl_find_oidname(oid->oid_name, parent);
 777         if (oidp != NULL) {
 778                 SYSCTL_WUNLOCK();
 779                 return (EEXIST);
 780         }
 781         sysctl_unregister_oid(oid);
 782         oid->oid_parent = parent;
 783         oid->oid_number = OID_AUTO;
 784         sysctl_register_oid(oid);
 785         SYSCTL_WUNLOCK();
 786         return (0);
 787 }
 788
 789 /*
 790  * Register the kernel's oids on startup.
 791  */
 792 SET_DECLARE(sysctl_set, struct sysctl_oid);
 793
 794 static void
 795 sysctl_register_all(void *arg)
 796 {
 797         struct sysctl_oid **oidp;
 798
 799         sx_init(&sysctlmemlock, "sysctl mem");
 800         SYSCTL_INIT();
 801         SYSCTL_WLOCK();
 802         SET_FOREACH(oidp, sysctl_set)
 803                 sysctl_register_oid(*oidp);
 804         SYSCTL_WUNLOCK();
 805 }
 806 SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, 0);
 807
 808 /*
 809  * "Staff-functions"
 810  *
 811  * These functions implement a presently undocumented interface
 812  * used by the sysctl program to walk the tree, and get the type
 813  * so it can print the value.
 814  * This interface is under work and consideration, and should probably
 815  * be killed with a big axe by the first person who can find the time.
 816  * (be aware though, that the proper interface isn't as obvious as it
 817  * may seem, there are various conflicting requirements.
 818  *
 819  * {0,0}        printf the entire MIB-tree.
 820  * {0,1,...}    return the name of the "..." OID.
 821  * {0,2,...}    return the next OID.
 822  * {0,3}        return the OID of the name in "new"
 823  * {0,4,...}    return the kind & format info for the "..." OID.
 824  * {0,5,...}    return the description of the "..." OID.
 825  * {0,6,...}    return the aggregation label of the "..." OID.
 826  */
 827
 828 #ifdef SYSCTL_DEBUG
 829 static void
 830 sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
 831 {
 832         int k;
 833         struct sysctl_oid *oidp;
 834
 835         SYSCTL_ASSERT_LOCKED();
 836         SLIST_FOREACH(oidp, l, oid_link) {
 837
 838                 for (k=0; k<i; k++)
 839                         printf(" ");
 840
 841                 printf("%d %s ", oidp->oid_number, oidp->oid_name);
 842
 843                 printf("%c%c",
 844                         oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
 845                         oidp->oid_kind & CTLFLAG_WR ? 'W':' ');
 846
 847                 if (oidp->oid_handler)
 848                         printf(" *Handler");
 849
 850                 switch (oidp->oid_kind & CTLTYPE) {
 851                         case CTLTYPE_NODE:
 852                                 printf(" Node\n");
 853                                 if (!oidp->oid_handler) {
 854                                         sysctl_sysctl_debug_dump_node(
 855                                             SYSCTL_CHILDREN(oidp), i + 2);
 856                                 }
 857                                 break;
 858                         case CTLTYPE_INT:    printf(" Int\n"); break;
 859                         case CTLTYPE_UINT:   printf(" u_int\n"); break;
 860                         case CTLTYPE_LONG:   printf(" Long\n"); break;
 861                         case CTLTYPE_ULONG:  printf(" u_long\n"); break;
 862                         case CTLTYPE_STRING: printf(" String\n"); break;
 863                         case CTLTYPE_S8:     printf(" int8_t\n"); break;
 864                         case CTLTYPE_S16:    printf(" int16_t\n"); break;
 865                         case CTLTYPE_S32:    printf(" int32_t\n"); break;
 866                         case CTLTYPE_S64:    printf(" int64_t\n"); break;
 867                         case CTLTYPE_U8:     printf(" uint8_t\n"); break;
 868                         case CTLTYPE_U16:    printf(" uint16_t\n"); break;
 869                         case CTLTYPE_U32:    printf(" uint32_t\n"); break;
 870                         case CTLTYPE_U64:    printf(" uint64_t\n"); break;
 871                         case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
 872                         default:             printf("\n");
 873                 }
 874
 875         }
 876 }
 877
 878 static int
 879 sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
 880 {
 881         struct rm_priotracker tracker;
 882         int error;
 883
 884         error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
 885         if (error)
 886                 return (error);
 887         SYSCTL_RLOCK(&tracker);
 888         sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
 889         SYSCTL_RUNLOCK(&tracker);
 890         return (ENOENT);
 891 }
 892
 893 SYSCTL_PROC(_sysctl, 0, debug, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
 894         0, 0, sysctl_sysctl_debug, "-", "");
 895 #endif
 896
 897 static int
 898 sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
 899 {
 900         int *name = (int *) arg1;
 901         u_int namelen = arg2;
 902         int error = 0;
 903         struct sysctl_oid *oid;
 904         struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
 905         struct rm_priotracker tracker;
 906         char buf[10];
 907
 908         SYSCTL_RLOCK(&tracker);
 909         while (namelen) {
 910                 if (!lsp) {
 911                         snprintf(buf,sizeof(buf),"%d",*name);
 912                         if (req->oldidx)
 913                                 error = SYSCTL_OUT(req, ".", 1);
 914                         if (!error)
 915                                 error = SYSCTL_OUT(req, buf, strlen(buf));
 916                         if (error)
 917                                 goto out;
 918                         namelen--;
 919                         name++;
 920                         continue;
 921                 }
 922                 lsp2 = NULL;
 923                 SLIST_FOREACH(oid, lsp, oid_link) {
 924                         if (oid->oid_number != *name)
 925                                 continue;
 926
 927                         if (req->oldidx)
 928                                 error = SYSCTL_OUT(req, ".", 1);
 929                         if (!error)
 930                                 error = SYSCTL_OUT(req, oid->oid_name,
 931                                         strlen(oid->oid_name));
 932                         if (error)
 933                                 goto out;
 934
 935                         namelen--;
 936                         name++;
 937
 938                         if ((oid->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 939                                 break;
 940
 941                         if (oid->oid_handler)
 942                                 break;
 943
 944                         lsp2 = SYSCTL_CHILDREN(oid);
 945                         break;
 946                 }
 947                 lsp = lsp2;
 948         }
 949         error = SYSCTL_OUT(req, "", 1);
 950  out:
 951         SYSCTL_RUNLOCK(&tracker);
 952         return (error);
 953 }
 954
 955 /*
 956  * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
 957  * capability mode.
 958  */
 959 static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
 960     sysctl_sysctl_name, "");
 961
 962 static int
 963 sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen,
 964         int *next, int *len, int level, struct sysctl_oid **oidpp)
 965 {
 966         struct sysctl_oid *oidp;
 967
 968         SYSCTL_ASSERT_LOCKED();
 969         *len = level;
 970         SLIST_FOREACH(oidp, lsp, oid_link) {
 971                 *next = oidp->oid_number;
 972                 *oidpp = oidp;
 973
 974                 if (oidp->oid_kind & CTLFLAG_SKIP)
 975                         continue;
 976
 977                 if (!namelen) {
 978                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 979                                 return (0);
 980                         if (oidp->oid_handler)
 981                                 /* We really should call the handler here...*/
 982                                 return (0);
 983                         lsp = SYSCTL_CHILDREN(oidp);
 984                         if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1,
 985                                 len, level+1, oidpp))
 986                                 return (0);
 987                         goto emptynode;
 988                 }
 989
 990                 if (oidp->oid_number < *name)
 991                         continue;
 992
 993                 if (oidp->oid_number > *name) {
 994                         if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
 995                                 return (0);
 996                         if (oidp->oid_handler)
 997                                 return (0);
 998                         lsp = SYSCTL_CHILDREN(oidp);
 999                         if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1,
1000                                 next+1, len, level+1, oidpp))
1001                                 return (0);
1002                         goto next;
1003                 }
1004                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
1005                         continue;
1006
1007                 if (oidp->oid_handler)
1008                         continue;
1009
1010                 lsp = SYSCTL_CHILDREN(oidp);
1011                 if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1,
1012                         len, level+1, oidpp))
1013                         return (0);
1014         next:
1015                 namelen = 1;
1016         emptynode:
1017                 *len = level;
1018         }
1019         return (1);
1020 }
1021
1022 static int
1023 sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
1024 {
1025         int *name = (int *) arg1;
1026         u_int namelen = arg2;
1027         int i, j, error;
1028         struct sysctl_oid *oid;
1029         struct sysctl_oid_list *lsp = &sysctl__children;
1030         struct rm_priotracker tracker;
1031         int newoid[CTL_MAXNAME];
1032
1033         SYSCTL_RLOCK(&tracker);
1034         i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
1035         SYSCTL_RUNLOCK(&tracker);
1036         if (i)
1037                 return (ENOENT);
1038         error = SYSCTL_OUT(req, newoid, j * sizeof (int));
1039         return (error);
1040 }
1041
1042 /*
1043  * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
1044  * capability mode.
1045  */
1046 static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
1047     sysctl_sysctl_next, "");
1048
1049 static int
1050 name2oid(char *name, int *oid, int *len, struct sysctl_oid **oidpp)
1051 {
1052         struct sysctl_oid *oidp;
1053         struct sysctl_oid_list *lsp = &sysctl__children;
1054         char *p;
1055
1056         SYSCTL_ASSERT_LOCKED();
1057
1058         for (*len = 0; *len < CTL_MAXNAME;) {
1059                 p = strsep(&name, ".");
1060
1061                 oidp = SLIST_FIRST(lsp);
1062                 for (;; oidp = SLIST_NEXT(oidp, oid_link)) {
1063                         if (oidp == NULL)
1064                                 return (ENOENT);
1065                         if (strcmp(p, oidp->oid_name) == 0)
1066                                 break;
1067                 }
1068                 *oid++ = oidp->oid_number;
1069                 (*len)++;
1070
1071                 if (name == NULL || *name == '\0') {
1072                         if (oidpp)
1073                                 *oidpp = oidp;
1074                         return (0);
1075                 }
1076
1077                 if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
1078                         break;
1079
1080                 if (oidp->oid_handler)
1081                         break;
1082
1083                 lsp = SYSCTL_CHILDREN(oidp);
1084         }
1085         return (ENOENT);
1086 }
1087
1088 static int
1089 sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
1090 {
1091         char *p;
1092         int error, oid[CTL_MAXNAME], len = 0;
1093         struct sysctl_oid *op = NULL;
1094         struct rm_priotracker tracker;
1095
1096         if (!req->newlen)
1097                 return (ENOENT);
1098         if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
1099                 return (ENAMETOOLONG);
1100
1101         p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);
1102
1103         error = SYSCTL_IN(req, p, req->newlen);
1104         if (error) {
1105                 free(p, M_SYSCTL);
1106                 return (error);
1107         }
1108
1109         p [req->newlen] = '\0';
1110
1111         SYSCTL_RLOCK(&tracker);
1112         error = name2oid(p, oid, &len, &op);
1113         SYSCTL_RUNLOCK(&tracker);
1114
1115         free(p, M_SYSCTL);
1116
1117         if (error)
1118                 return (error);
1119
1120         error = SYSCTL_OUT(req, oid, len * sizeof *oid);
1121         return (error);
1122 }
1123
1124 /*
1125  * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
1126  * capability mode.
1127  */
1128 SYSCTL_PROC(_sysctl, 3, name2oid,
1129     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE
1130     | CTLFLAG_CAPRW, 0, 0, sysctl_sysctl_name2oid, "I", "");
1131
1132 static int
1133 sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
1134 {
1135         struct sysctl_oid *oid;
1136         struct rm_priotracker tracker;
1137         int error;
1138
1139         SYSCTL_RLOCK(&tracker);
1140         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
1141         if (error)
1142                 goto out;
1143
1144         if (oid->oid_fmt == NULL) {
1145                 error = ENOENT;
1146                 goto out;
1147         }
1148         error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
1149         if (error)
1150                 goto out;
1151         error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
1152  out:
1153         SYSCTL_RUNLOCK(&tracker);
1154         return (error);
1155 }
1156
1157
1158 static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
1159     sysctl_sysctl_oidfmt, "");
1160
1161 static int
1162 sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
1163 {
1164         struct sysctl_oid *oid;
1165         struct rm_priotracker tracker;
1166         int error;
1167
1168         SYSCTL_RLOCK(&tracker);
1169         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
1170         if (error)
1171                 goto out;
1172
1173         if (oid->oid_descr == NULL) {
1174                 error = ENOENT;
1175                 goto out;
1176         }
1177         error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
1178  out:
1179         SYSCTL_RUNLOCK(&tracker);
1180         return (error);
1181 }
1182
1183 static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_CAPRD,
1184     sysctl_sysctl_oiddescr, "");
1185
1186 static int
1187 sysctl_sysctl_oidlabel(SYSCTL_HANDLER_ARGS)
1188 {
1189         struct sysctl_oid *oid;
1190         struct rm_priotracker tracker;
1191         int error;
1192
1193         SYSCTL_RLOCK(&tracker);
1194         error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
1195         if (error)
1196                 goto out;
1197
1198         if (oid->oid_label == NULL) {
1199                 error = ENOENT;
1200                 goto out;
1201         }
1202         error = SYSCTL_OUT(req, oid->oid_label, strlen(oid->oid_label) + 1);
1203  out:
1204         SYSCTL_RUNLOCK(&tracker);
1205         return (error);
1206 }
1207
1208 static SYSCTL_NODE(_sysctl, 6, oidlabel,
1209     CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidlabel, "");
1210
1211 /*
1212  * Default "handler" functions.
1213  */
1214
1215 /*
1216  * Handle a bool.
1217  * Two cases:
1218  *     a variable:  point arg1 at it.
1219  *     a constant:  pass it in arg2.
1220  */
1221
1222 int
1223 sysctl_handle_bool(SYSCTL_HANDLER_ARGS)
1224 {
1225         uint8_t temp;
1226         int error;
1227
1228         /*
1229          * Attempt to get a coherent snapshot by making a copy of the data.
1230          */
1231         if (arg1)
1232                 temp = *(bool *)arg1 ? 1 : 0;
1233         else
1234                 temp = arg2 ? 1 : 0;
1235
1236         error = SYSCTL_OUT(req, &temp, sizeof(temp));
1237         if (error || !req->newptr)
1238                 return (error);
1239
1240         if (!arg1)
1241                 error = EPERM;
1242         else {
1243                 error = SYSCTL_IN(req, &temp, sizeof(temp));
1244                 if (!error)
1245                         *(bool *)arg1 = temp ? 1 : 0;
1246         }
1247         return (error);
1248 }
1249
1250 /*
1251  * Handle an int8_t, signed or unsigned.
1252  * Two cases:
1253  *     a variable:  point arg1 at it.
1254  *     a constant:  pass it in arg2.
1255  */
1256
1257 int
1258 sysctl_handle_8(SYSCTL_HANDLER_ARGS)
1259 {
1260         int8_t tmpout;
1261         int error = 0;
1262
1263         /*
1264          * Attempt to get a coherent snapshot by making a copy of the data.
1265          */
1266         if (arg1)
1267                 tmpout = *(int8_t *)arg1;
1268         else
1269                 tmpout = arg2;
1270         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1271
1272         if (error || !req->newptr)
1273                 return (error);
1274
1275         if (!arg1)
1276                 error = EPERM;
1277         else
1278                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1279         return (error);
1280 }
1281
1282 /*
1283  * Handle an int16_t, signed or unsigned.
1284  * Two cases:
1285  *     a variable:  point arg1 at it.
1286  *     a constant:  pass it in arg2.
1287  */
1288
1289 int
1290 sysctl_handle_16(SYSCTL_HANDLER_ARGS)
1291 {
1292         int16_t tmpout;
1293         int error = 0;
1294
1295         /*
1296          * Attempt to get a coherent snapshot by making a copy of the data.
1297          */
1298         if (arg1)
1299                 tmpout = *(int16_t *)arg1;
1300         else
1301                 tmpout = arg2;
1302         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1303
1304         if (error || !req->newptr)
1305                 return (error);
1306
1307         if (!arg1)
1308                 error = EPERM;
1309         else
1310                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1311         return (error);
1312 }
1313
1314 /*
1315  * Handle an int32_t, signed or unsigned.
1316  * Two cases:
1317  *     a variable:  point arg1 at it.
1318  *     a constant:  pass it in arg2.
1319  */
1320
1321 int
1322 sysctl_handle_32(SYSCTL_HANDLER_ARGS)
1323 {
1324         int32_t tmpout;
1325         int error = 0;
1326
1327         /*
1328          * Attempt to get a coherent snapshot by making a copy of the data.
1329          */
1330         if (arg1)
1331                 tmpout = *(int32_t *)arg1;
1332         else
1333                 tmpout = arg2;
1334         error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));
1335
1336         if (error || !req->newptr)
1337                 return (error);
1338
1339         if (!arg1)
1340                 error = EPERM;
1341         else
1342                 error = SYSCTL_IN(req, arg1, sizeof(tmpout));
1343         return (error);
1344 }
1345
1346 /*
1347  * Handle an int, signed or unsigned.
1348  * Two cases:
1349  *     a variable:  point arg1 at it.
1350  *     a constant:  pass it in arg2.
1351  */
1352
1353 int
1354 sysctl_handle_int(SYSCTL_HANDLER_ARGS)
1355 {
1356         int tmpout, error = 0;
1357
1358         /*
1359          * Attempt to get a coherent snapshot by making a copy of the data.
1360          */
1361         if (arg1)
1362                 tmpout = *(int *)arg1;
1363         else
1364                 tmpout = arg2;
1365         error = SYSCTL_OUT(req, &tmpout, sizeof(int));
1366
1367         if (error || !req->newptr)
1368                 return (error);
1369
1370         if (!arg1)
1371                 error = EPERM;
1372         else
1373                 error = SYSCTL_IN(req, arg1, sizeof(int));
1374         return (error);
1375 }
1376
1377 /*
1378  * Based on on sysctl_handle_int() convert milliseconds into ticks.
1379  * Note: this is used by TCP.
1380  */
1381
1382 int
1383 sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
1384 {
1385         int error, s, tt;
1386
1387         tt = *(int *)arg1;
1388         s = (int)((int64_t)tt * 1000 / hz);
1389
1390         error = sysctl_handle_int(oidp, &s, 0, req);
1391         if (error || !req->newptr)
1392                 return (error);
1393
1394         tt = (int)((int64_t)s * hz / 1000);
1395         if (tt < 1)
1396                 return (EINVAL);
1397
1398         *(int *)arg1 = tt;
1399         return (0);
1400 }
1401
1402
1403 /*
1404  * Handle a long, signed or unsigned.
1405  * Two cases:
1406  *     a variable:  point arg1 at it.
1407  *     a constant:  pass it in arg2.
1408  */
1409
1410 int
1411 sysctl_handle_long(SYSCTL_HANDLER_ARGS)
1412 {
1413         int error = 0;
1414         long tmplong;
1415 #ifdef SCTL_MASK32
1416         int tmpint;
1417 #endif
1418
1419         /*
1420          * Attempt to get a coherent snapshot by making a copy of the data.
1421          */
1422         if (arg1)
1423                 tmplong = *(long *)arg1;
1424         else
1425                 tmplong = arg2;
1426 #ifdef SCTL_MASK32
1427         if (req->flags & SCTL_MASK32) {
1428                 tmpint = tmplong;
1429                 error = SYSCTL_OUT(req, &tmpint, sizeof(int));
1430         } else
1431 #endif
1432                 error = SYSCTL_OUT(req, &tmplong, sizeof(long));
1433
1434         if (error || !req->newptr)
1435                 return (error);
1436
1437         if (!arg1)
1438                 error = EPERM;
1439 #ifdef SCTL_MASK32
1440         else if (req->flags & SCTL_MASK32) {
1441                 error = SYSCTL_IN(req, &tmpint, sizeof(int));
1442                 *(long *)arg1 = (long)tmpint;
1443         }
1444 #endif
1445         else
1446                 error = SYSCTL_IN(req, arg1, sizeof(long));
1447         return (error);
1448 }
1449
1450 /*
1451  * Handle a 64 bit int, signed or unsigned.
1452  * Two cases:
1453  *     a variable:  point arg1 at it.
1454  *     a constant:  pass it in arg2.
1455  */
1456 int
1457 sysctl_handle_64(SYSCTL_HANDLER_ARGS)
1458 {
1459         int error = 0;
1460         uint64_t tmpout;
1461
1462         /*
1463          * Attempt to get a coherent snapshot by making a copy of the data.
1464          */
1465         if (arg1)
1466                 tmpout = *(uint64_t *)arg1;
1467         else
1468                 tmpout = arg2;
1469         error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));
1470
1471         if (error || !req->newptr)
1472                 return (error);
1473
1474         if (!arg1)
1475                 error = EPERM;
1476         else
1477                 error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
1478         return (error);
1479 }
1480
1481 /*
1482  * Handle our generic '\0' terminated 'C' string.
1483  * Two cases:
1484  *      a variable string:  point arg1 at it, arg2 is max length.
1485  *      a constant string:  point arg1 at it, arg2 is zero.
1486  */
1487
1488 int
1489 sysctl_handle_string(SYSCTL_HANDLER_ARGS)
1490 {
1491         size_t outlen;
1492         int error = 0, ro_string = 0;
1493
1494         /*
1495          * A zero-length buffer indicates a fixed size read-only
1496          * string:
1497          */
1498         if (arg2 == 0) {
1499                 arg2 = strlen((char *)arg1) + 1;
1500                 ro_string = 1;
1501         }
1502
1503         if (req->oldptr != NULL) {
1504                 char *tmparg;
1505
1506                 if (ro_string) {
1507                         tmparg = arg1;
1508                 } else {
1509                         /* try to make a coherent snapshot of the string */
1510                         tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);
1511                         memcpy(tmparg, arg1, arg2);
1512                 }
1513
1514                 outlen = strnlen(tmparg, arg2 - 1) + 1;
1515                 error = SYSCTL_OUT(req, tmparg, outlen);
1516
1517                 if (!ro_string)
1518                         free(tmparg, M_SYSCTLTMP);
1519         } else {
1520                 outlen = strnlen((char *)arg1, arg2 - 1) + 1;
1521                 error = SYSCTL_OUT(req, NULL, outlen);
1522         }
1523         if (error || !req->newptr)
1524                 return (error);
1525
1526         if ((req->newlen - req->newidx) >= arg2) {
1527                 error = EINVAL;
1528         } else {
1529                 arg2 = (req->newlen - req->newidx);
1530                 error = SYSCTL_IN(req, arg1, arg2);
1531                 ((char *)arg1)[arg2] = '\0';
1532         }
1533         return (error);
1534 }
1535
1536 /*
1537  * Handle any kind of opaque data.
1538  * arg1 points to it, arg2 is the size.
1539  */
1540
1541 int
1542 sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
1543 {
1544         int error, tries;
1545         u_int generation;
1546         struct sysctl_req req2;
1547
1548         /*
1549          * Attempt to get a coherent snapshot, by using the thread
1550          * pre-emption counter updated from within mi_switch() to
1551          * determine if we were pre-empted during a bcopy() or
1552          * copyout(). Make 3 attempts at doing this before giving up.
1553          * If we encounter an error, stop immediately.
1554          */
1555         tries = 0;
1556         req2 = *req;
1557 retry:
1558         generation = curthread->td_generation;
1559         error = SYSCTL_OUT(req, arg1, arg2);
1560         if (error)
1561                 return (error);
1562         tries++;
1563         if (generation != curthread->td_generation && tries < 3) {
1564                 *req = req2;
1565                 goto retry;
1566         }
1567
1568         error = SYSCTL_IN(req, arg1, arg2);
1569
1570         return (error);
1571 }
1572
1573 /*
1574  * Transfer functions to/from kernel space.
1575  * XXX: rather untested at this point
1576  */
1577 static int
1578 sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
1579 {
1580         size_t i = 0;
1581
1582         if (req->oldptr) {
1583                 i = l;
1584                 if (req->oldlen <= req->oldidx)
1585                         i = 0;
1586                 else
1587                         if (i > req->oldlen - req->oldidx)
1588                                 i = req->oldlen - req->oldidx;
1589                 if (i > 0)
1590                         bcopy(p, (char *)req->oldptr + req->oldidx, i);
1591         }
1592         req->oldidx += l;
1593         if (req->oldptr && i != l)
1594                 return (ENOMEM);
1595         return (0);
1596 }
1597
1598 static int
1599 sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
1600 {
1601         if (!req->newptr)
1602                 return (0);
1603         if (req->newlen - req->newidx < l)
1604                 return (EINVAL);
1605         bcopy((char *)req->newptr + req->newidx, p, l);
1606         req->newidx += l;
1607         return (0);
1608 }
1609
1610 int
1611 kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
1612     size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
1613 {
1614         int error = 0;
1615         struct sysctl_req req;
1616
1617         bzero(&req, sizeof req);
1618
1619         req.td = td;
1620         req.flags = flags;
1621
1622         if (oldlenp) {
1623                 req.oldlen = *oldlenp;
1624         }
1625         req.validlen = req.oldlen;
1626
1627         if (old) {
1628                 req.oldptr= old;
1629         }
1630
1631         if (new != NULL) {
1632                 req.newlen = newlen;
1633                 req.newptr = new;
1634         }
1635
1636         req.oldfunc = sysctl_old_kernel;
1637         req.newfunc = sysctl_new_kernel;
1638         req.lock = REQ_UNWIRED;
1639
1640         error = sysctl_root(0, name, namelen, &req);
1641
1642         if (req.lock == REQ_WIRED && req.validlen > 0)
1643                 vsunlock(req.oldptr, req.validlen);
1644
1645         if (error && error != ENOMEM)
1646                 return (error);
1647
1648         if (retval) {
1649                 if (req.oldptr && req.oldidx > req.validlen)
1650                         *retval = req.validlen;
1651                 else
1652                         *retval = req.oldidx;
1653         }
1654         return (error);
1655 }
1656
1657 int
1658 kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
1659     void *new, size_t newlen, size_t *retval, int flags)
1660 {
1661         int oid[CTL_MAXNAME];
1662         size_t oidlen, plen;
1663         int error;
1664
1665         oid[0] = 0;             /* sysctl internal magic */
1666         oid[1] = 3;             /* name2oid */
1667         oidlen = sizeof(oid);
1668
1669         error = kernel_sysctl(td, oid, 2, oid, &oidlen,
1670             (void *)name, strlen(name), &plen, flags);
1671         if (error)
1672                 return (error);
1673
1674         error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
1675             new, newlen, retval, flags);
1676         return (error);
1677 }
1678
1679 /*
1680  * Transfer function to/from user space.
1681  */
1682 static int
1683 sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
1684 {
1685         size_t i, len, origidx;
1686         int error;
1687
1688         origidx = req->oldidx;
1689         req->oldidx += l;
1690         if (req->oldptr == NULL)
1691                 return (0);
1692         /*
1693          * If we have not wired the user supplied buffer and we are currently
1694          * holding locks, drop a witness warning, as it's possible that
1695          * write operations to the user page can sleep.
1696          */
1697         if (req->lock != REQ_WIRED)
1698                 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
1699                     "sysctl_old_user()");
1700         i = l;
1701         len = req->validlen;
1702         if (len <= origidx)
1703                 i = 0;
1704         else {
1705                 if (i > len - origidx)
1706                         i = len - origidx;
1707                 if (req->lock == REQ_WIRED) {
1708                         error = copyout_nofault(p, (char *)req->oldptr +
1709                             origidx, i);
1710                 } else
1711                         error = copyout(p, (char *)req->oldptr + origidx, i);
1712                 if (error != 0)
1713                         return (error);
1714         }
1715         if (i < l)
1716                 return (ENOMEM);
1717         return (0);
1718 }
1719
1720 static int
1721 sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
1722 {
1723         int error;
1724
1725         if (!req->newptr)
1726                 return (0);
1727         if (req->newlen - req->newidx < l)
1728                 return (EINVAL);
1729         WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
1730             "sysctl_new_user()");
1731         error = copyin((char *)req->newptr + req->newidx, p, l);
1732         req->newidx += l;
1733         return (error);
1734 }
1735
1736 /*
1737  * Wire the user space destination buffer.  If set to a value greater than
1738  * zero, the len parameter limits the maximum amount of wired memory.
1739  */
1740 int
1741 sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
1742 {
1743         int ret;
1744         size_t wiredlen;
1745
1746         wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
1747         ret = 0;
1748         if (req->lock != REQ_WIRED && req->oldptr &&
1749             req->oldfunc == sysctl_old_user) {
1750                 if (wiredlen != 0) {
1751                         ret = vslock(req->oldptr, wiredlen);
1752                         if (ret != 0) {
1753                                 if (ret != ENOMEM)
1754                                         return (ret);
1755                                 wiredlen = 0;
1756                         }
1757                 }
1758                 req->lock = REQ_WIRED;
1759                 req->validlen = wiredlen;
1760         }
1761         return (0);
1762 }
1763
1764 int
1765 sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
1766     int *nindx, struct sysctl_req *req)
1767 {
1768         struct sysctl_oid_list *lsp;
1769         struct sysctl_oid *oid;
1770         int indx;
1771
1772         SYSCTL_ASSERT_LOCKED();
1773         lsp = &sysctl__children;
1774         indx = 0;
1775         while (indx < CTL_MAXNAME) {
1776                 SLIST_FOREACH(oid, lsp, oid_link) {
1777                         if (oid->oid_number == name[indx])
1778                                 break;
1779                 }
1780                 if (oid == NULL)
1781                         return (ENOENT);
1782
1783                 indx++;
1784                 if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1785                         if (oid->oid_handler != NULL || indx == namelen) {
1786                                 *noid = oid;
1787                                 if (nindx != NULL)
1788                                         *nindx = indx;
1789                                 KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
1790                                     ("%s found DYING node %p", __func__, oid));
1791                                 return (0);
1792                         }
1793                         lsp = SYSCTL_CHILDREN(oid);
1794                 } else if (indx == namelen) {
1795                         *noid = oid;
1796                         if (nindx != NULL)
1797                                 *nindx = indx;
1798                         KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
1799                             ("%s found DYING node %p", __func__, oid));
1800                         return (0);
1801                 } else {
1802                         return (ENOTDIR);
1803                 }
1804         }
1805         return (ENOENT);
1806 }
1807
1808 /*
1809  * Traverse our tree, and find the right node, execute whatever it points
1810  * to, and return the resulting error code.
1811  */
1812
1813 static int
1814 sysctl_root(SYSCTL_HANDLER_ARGS)
1815 {
1816         struct sysctl_oid *oid;
1817         struct rm_priotracker tracker;
1818         int error, indx, lvl;
1819
1820         SYSCTL_RLOCK(&tracker);
1821
1822         error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
1823         if (error)
1824                 goto out;
1825
1826         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1827                 /*
1828                  * You can't call a sysctl when it's a node, but has
1829                  * no handler.  Inform the user that it's a node.
1830                  * The indx may or may not be the same as namelen.
1831                  */
1832                 if (oid->oid_handler == NULL) {
1833                         error = EISDIR;
1834                         goto out;
1835                 }
1836         }
1837
1838         /* Is this sysctl writable? */
1839         if (req->newptr && !(oid->oid_kind & CTLFLAG_WR)) {
1840                 error = EPERM;
1841                 goto out;
1842         }
1843
1844         KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));
1845
1846 #ifdef CAPABILITY_MODE
1847         /*
1848          * If the process is in capability mode, then don't permit reading or
1849          * writing unless specifically granted for the node.
1850          */
1851         if (IN_CAPABILITY_MODE(req->td)) {
1852                 if ((req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD)) ||
1853                     (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))) {
1854                         error = EPERM;
1855                         goto out;
1856                 }
1857         }
1858 #endif
1859
1860         /* Is this sysctl sensitive to securelevels? */
1861         if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
1862                 lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
1863                 error = securelevel_gt(req->td->td_ucred, lvl);
1864                 if (error)
1865                         goto out;
1866         }
1867
1868         /* Is this sysctl writable by only privileged users? */
1869         if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
1870                 int priv;
1871
1872                 if (oid->oid_kind & CTLFLAG_PRISON)
1873                         priv = PRIV_SYSCTL_WRITEJAIL;
1874 #ifdef VIMAGE
1875                 else if ((oid->oid_kind & CTLFLAG_VNET) &&
1876                      prison_owns_vnet(req->td->td_ucred))
1877                         priv = PRIV_SYSCTL_WRITEJAIL;
1878 #endif
1879                 else
1880                         priv = PRIV_SYSCTL_WRITE;
1881                 error = priv_check(req->td, priv);
1882                 if (error)
1883                         goto out;
1884         }
1885
1886         if (!oid->oid_handler) {
1887                 error = EINVAL;
1888                 goto out;
1889         }
1890
1891         if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
1892                 arg1 = (int *)arg1 + indx;
1893                 arg2 -= indx;
1894         } else {
1895                 arg1 = oid->oid_arg1;
1896                 arg2 = oid->oid_arg2;
1897         }
1898 #ifdef MAC
1899         error = mac_system_check_sysctl(req->td->td_ucred, oid, arg1, arg2,
1900             req);
1901         if (error != 0)
1902                 goto out;
1903 #endif
1904 #ifdef VIMAGE
1905         if ((oid->oid_kind & CTLFLAG_VNET) && arg1 != NULL)
1906                 arg1 = (void *)(curvnet->vnet_data_base + (uintptr_t)arg1);
1907 #endif
1908         error = sysctl_root_handler_locked(oid, arg1, arg2, req, &tracker);
1909
1910 out:
1911         SYSCTL_RUNLOCK(&tracker);
1912         return (error);
1913 }
1914
1915 #ifndef _SYS_SYSPROTO_H_
1916 struct sysctl_args {
1917         int     *name;
1918         u_int   namelen;
1919         void    *old;
1920         size_t  *oldlenp;
1921         void    *new;
1922         size_t  newlen;
1923 };
1924 #endif
1925 int
1926 sys___sysctl(struct thread *td, struct sysctl_args *uap)
1927 {
1928         int error, i, name[CTL_MAXNAME];
1929         size_t j;
1930
1931         if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
1932                 return (EINVAL);
1933
1934         error = copyin(uap->name, &name, uap->namelen * sizeof(int));
1935         if (error)
1936                 return (error);
1937
1938         error = userland_sysctl(td, name, uap->namelen,
1939                 uap->old, uap->oldlenp, 0,
1940                 uap->new, uap->newlen, &j, 0);
1941         if (error && error != ENOMEM)
1942                 return (error);
1943         if (uap->oldlenp) {
1944                 i = copyout(&j, uap->oldlenp, sizeof(j));
1945                 if (i)
1946                         return (i);
1947         }
1948         return (error);
1949 }
1950
1951 /*
1952  * This is used from various compatibility syscalls too.  That's why name
1953  * must be in kernel space.
1954  */
1955 int
1956 userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
1957     size_t *oldlenp, int inkernel, void *new, size_t newlen, size_t *retval,
1958     int flags)
1959 {
1960         int error = 0, memlocked;
1961         struct sysctl_req req;
1962
1963         bzero(&req, sizeof req);
1964
1965         req.td = td;
1966         req.flags = flags;
1967
1968         if (oldlenp) {
1969                 if (inkernel) {
1970                         req.oldlen = *oldlenp;
1971                 } else {
1972                         error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
1973                         if (error)
1974                                 return (error);
1975                 }
1976         }
1977         req.validlen = req.oldlen;
1978
1979         if (old) {
1980                 if (!useracc(old, req.oldlen, VM_PROT_WRITE))
1981                         return (EFAULT);
1982                 req.oldptr= old;
1983         }
1984
1985         if (new != NULL) {
1986                 if (!useracc(new, newlen, VM_PROT_READ))
1987                         return (EFAULT);
1988                 req.newlen = newlen;
1989                 req.newptr = new;
1990         }
1991
1992         req.oldfunc = sysctl_old_user;
1993         req.newfunc = sysctl_new_user;
1994         req.lock = REQ_UNWIRED;
1995
1996 #ifdef KTRACE
1997         if (KTRPOINT(curthread, KTR_SYSCTL))
1998                 ktrsysctl(name, namelen);
1999 #endif
2000
2001         if (req.oldptr && req.oldlen > PAGE_SIZE) {
2002                 memlocked = 1;
2003                 sx_xlock(&sysctlmemlock);
2004         } else
2005                 memlocked = 0;
2006         CURVNET_SET(TD_TO_VNET(td));
2007
2008         for (;;) {
2009                 req.oldidx = 0;
2010                 req.newidx = 0;
2011                 error = sysctl_root(0, name, namelen, &req);
2012                 if (error != EAGAIN)
2013                         break;
2014                 kern_yield(PRI_USER);
2015         }
2016
2017         CURVNET_RESTORE();
2018
2019         if (req.lock == REQ_WIRED && req.validlen > 0)
2020                 vsunlock(req.oldptr, req.validlen);
2021         if (memlocked)
2022                 sx_xunlock(&sysctlmemlock);
2023
2024         if (error && error != ENOMEM)
2025                 return (error);
2026
2027         if (retval) {
2028                 if (req.oldptr && req.oldidx > req.validlen)
2029                         *retval = req.validlen;
2030                 else
2031                         *retval = req.oldidx;
2032         }
2033         return (error);
2034 }
2035
2036 /*
2037  * Drain into a sysctl struct.  The user buffer should be wired if a page
2038  * fault would cause issue.
2039  */
2040 static int
2041 sbuf_sysctl_drain(void *arg, const char *data, int len)
2042 {
2043         struct sysctl_req *req = arg;
2044         int error;
2045
2046         error = SYSCTL_OUT(req, data, len);
2047         KASSERT(error >= 0, ("Got unexpected negative value %d", error));
2048         return (error == 0 ? len : -error);
2049 }
2050
2051 struct sbuf *
2052 sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length,
2053     struct sysctl_req *req)
2054 {
2055
2056         /* Supply a default buffer size if none given. */
2057         if (buf == NULL && length == 0)
2058                 length = 64;
2059         s = sbuf_new(s, buf, length, SBUF_FIXEDLEN | SBUF_INCLUDENUL);
2060         sbuf_set_drain(s, sbuf_sysctl_drain, req);
2061         return (s);
2062 }