/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Mike Karels at Berkeley Software Design, Inc.
 *
 * Quite extensively rewritten by Poul-Henning Kamp of the FreeBSD
 * project, to make these variables more userfriendly.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_capsicum.h"
#include "opt_ddb.h"
#include "opt_ktrace.h"
#include "opt_sysctl.h"

#include <sys/param.h>
#include <sys/fail.h>
#include <sys/systm.h>
#include <sys/capsicum.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/jail.h>
#include <sys/kdb.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/rmlock.h>
#include <sys/sbuf.h>
#include <sys/sx.h>
#include <sys/sysproto.h>
#include <sys/uio.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#ifdef DDB
#include <ddb/ddb.h>
#include <ddb/db_lex.h>
#endif

#include <net/vnet.h>

#include <security/mac/mac_framework.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>

static MALLOC_DEFINE(M_SYSCTL, "sysctl", "sysctl internal magic");
static MALLOC_DEFINE(M_SYSCTLOID, "sysctloid", "sysctl dynamic oids");
static MALLOC_DEFINE(M_SYSCTLTMP, "sysctltmp", "sysctl temp output buffer");

RB_GENERATE(sysctl_oid_list, sysctl_oid, oid_link, cmp_sysctl_oid);

/*
 * The sysctllock protects the MIB tree.  It also protects sysctl
 * contexts used with dynamic sysctls.  The sysctl_register_oid() and
 * sysctl_unregister_oid() routines require the sysctllock to already
 * be held, so the sysctl_wlock() and sysctl_wunlock() routines are
 * provided for the few places in the kernel which need to use that
 * API rather than using the dynamic API.  Use of the dynamic API is
 * strongly encouraged for most code.
 *
 * The sysctlmemlock is used to limit the amount of user memory wired for
 * sysctl requests.  This is implemented by serializing any userland
 * sysctl requests larger than a single page via an exclusive lock.
 *
 * The sysctlstringlock is used to protect concurrent access to writable
 * string nodes in sysctl_handle_string().
 */
static struct rmlock sysctllock;
static struct sx __exclusive_cache_line sysctlmemlock;
static struct sx sysctlstringlock;

#define SYSCTL_WLOCK()          rm_wlock(&sysctllock)
#define SYSCTL_WUNLOCK()        rm_wunlock(&sysctllock)
#define SYSCTL_RLOCK(tracker)   rm_rlock(&sysctllock, (tracker))
#define SYSCTL_RUNLOCK(tracker) rm_runlock(&sysctllock, (tracker))
#define SYSCTL_WLOCKED()        rm_wowned(&sysctllock)
#define SYSCTL_ASSERT_LOCKED()  rm_assert(&sysctllock, RA_LOCKED)
#define SYSCTL_ASSERT_WLOCKED() rm_assert(&sysctllock, RA_WLOCKED)
#define SYSCTL_ASSERT_RLOCKED() rm_assert(&sysctllock, RA_RLOCKED)
#define SYSCTL_INIT()           rm_init_flags(&sysctllock, "sysctl lock", \
                                    RM_SLEEPABLE)
#define SYSCTL_SLEEP(ch, wmesg, timo)                                   \
                                rm_sleep(ch, &sysctllock, 0, wmesg, timo)

static int sysctl_root(SYSCTL_HANDLER_ARGS);

/* Root list */
struct sysctl_oid_list sysctl__children = RB_INITIALIZER(&sysctl__children);

static char*    sysctl_escape_name(const char*);
static int      sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del,
                    int recurse);
static int      sysctl_old_kernel(struct sysctl_req *, const void *, size_t);
static int      sysctl_new_kernel(struct sysctl_req *, void *, size_t);
static int      name2oid(const char *, int *, int *, struct sysctl_oid **);

static struct sysctl_oid *
sysctl_find_oidname(const char *name, struct sysctl_oid_list *list)
{
        struct sysctl_oid *oidp;

        SYSCTL_ASSERT_LOCKED();
        SYSCTL_FOREACH(oidp, list) {
                if (strcmp(oidp->oid_name, name) == 0) {
                        return (oidp);
                }
        }
        return (NULL);
}

static struct sysctl_oid *
sysctl_find_oidnamelen(const char *name, size_t len,
    struct sysctl_oid_list *list)
{
        struct sysctl_oid *oidp;

        SYSCTL_ASSERT_LOCKED();
        SYSCTL_FOREACH(oidp, list) {
                if (strncmp(oidp->oid_name, name, len) == 0 &&
                    oidp->oid_name[len] == '\0')
                        return (oidp);
        }
        return (NULL);
}

/*
 * Initialization of the MIB tree.
 *
 * Order by number in each list.
 */
void
sysctl_wlock(void)
{

        SYSCTL_WLOCK();
}

void
sysctl_wunlock(void)
{

        SYSCTL_WUNLOCK();
}

static int
sysctl_root_handler_locked(struct sysctl_oid *oid, void *arg1, intmax_t arg2,
    struct sysctl_req *req, struct rm_priotracker *tracker)
{
        int error;

        if (oid->oid_kind & CTLFLAG_DYN)
                atomic_add_int(&oid->oid_running, 1);

        if (tracker != NULL)
                SYSCTL_RUNLOCK(tracker);
        else
                SYSCTL_WUNLOCK();

        /*
         * Treat set CTLFLAG_NEEDGIANT and unset CTLFLAG_MPSAFE flags the same,
         * untill we're ready to remove all traces of Giant from sysctl(9).
         */
        if ((oid->oid_kind & CTLFLAG_NEEDGIANT) ||
            (!(oid->oid_kind & CTLFLAG_MPSAFE)))
                mtx_lock(&Giant);
        error = oid->oid_handler(oid, arg1, arg2, req);
        if ((oid->oid_kind & CTLFLAG_NEEDGIANT) ||
            (!(oid->oid_kind & CTLFLAG_MPSAFE)))
                mtx_unlock(&Giant);

        KFAIL_POINT_ERROR(_debug_fail_point, sysctl_running, error);

        if (tracker != NULL)
                SYSCTL_RLOCK(tracker);
        else
                SYSCTL_WLOCK();

        if (oid->oid_kind & CTLFLAG_DYN) {
                if (atomic_fetchadd_int(&oid->oid_running, -1) == 1 &&
                    (oid->oid_kind & CTLFLAG_DYING) != 0)
                        wakeup(&oid->oid_running);
        }

        return (error);
}

static void
sysctl_load_tunable_by_oid_locked(struct sysctl_oid *oidp)
{
        struct sysctl_req req;
        struct sysctl_oid *curr;
        char *penv = NULL;
        char path[96];
        ssize_t rem = sizeof(path);
        ssize_t len;
        uint8_t data[512] __aligned(sizeof(uint64_t));
        int size;
        int error;

        path[--rem] = 0;

        for (curr = oidp; curr != NULL; curr = SYSCTL_PARENT(curr)) {
                len = strlen(curr->oid_name);
                rem -= len;
                if (curr != oidp)
                        rem -= 1;
                if (rem < 0) {
                        printf("OID path exceeds %d bytes\n", (int)sizeof(path));
                        return;
                }
                memcpy(path + rem, curr->oid_name, len);
                if (curr != oidp)
                        path[rem + len] = '.';
        }

        memset(&req, 0, sizeof(req));

        req.td = curthread;
        req.oldfunc = sysctl_old_kernel;
        req.newfunc = sysctl_new_kernel;
        req.lock = REQ_UNWIRED;

        switch (oidp->oid_kind & CTLTYPE) {
        case CTLTYPE_INT:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_UINT:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_LONG:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(long), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_ULONG:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(long), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_S8:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int8_t), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_S16:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int16_t), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_S32:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int32_t), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_S64:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(int64_t), GETENV_SIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_U8:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(uint8_t), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_U16:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(uint16_t), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_U32:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(uint32_t), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_U64:
                if (getenv_array(path + rem, data, sizeof(data), &size,
                    sizeof(uint64_t), GETENV_UNSIGNED) == 0)
                        return;
                req.newlen = size;
                req.newptr = data;
                break;
        case CTLTYPE_STRING:
                penv = kern_getenv(path + rem);
                if (penv == NULL)
                        return;
                req.newlen = strlen(penv);
                req.newptr = penv;
                break;
        default:
                return;
        }
        error = sysctl_root_handler_locked(oidp, oidp->oid_arg1,
            oidp->oid_arg2, &req, NULL);
        if (error != 0)
                printf("Setting sysctl %s failed: %d\n", path + rem, error);
        if (penv != NULL)
                freeenv(penv);
}

/*
 * Locate the path to a given oid.  Returns the length of the resulting path,
 * or -1 if the oid was not found.  nodes must have room for CTL_MAXNAME
 * elements.
 */
static int
sysctl_search_oid(struct sysctl_oid **nodes, struct sysctl_oid *needle)
{
        int indx;

        SYSCTL_ASSERT_LOCKED();
        indx = 0;
        /*
         * Do a depth-first search of the oid tree, looking for 'needle'. Start
         * with the first child of the root.
         */
        nodes[indx] = RB_MIN(sysctl_oid_list, &sysctl__children);
        for (;;) {
                if (nodes[indx] == needle)
                        return (indx + 1);

                if (nodes[indx] == NULL) {
                        /* Node has no more siblings, so back up to parent. */
                        if (indx-- == 0) {
                                /* Retreat to root, so give up. */
                                break;
                        }
                } else if ((nodes[indx]->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        /* Node has children. */
                        if (++indx == CTL_MAXNAME) {
                                /* Max search depth reached, so give up. */
                                break;
                        }
                        /* Start with the first child. */
                        nodes[indx] = RB_MIN(sysctl_oid_list,
                            &nodes[indx - 1]->oid_children);
                        continue;
                }
                /* Consider next sibling. */
                nodes[indx] = RB_NEXT(sysctl_oid_list, NULL, nodes[indx]);
        }
        return (-1);
}

static void
sysctl_warn_reuse(const char *func, struct sysctl_oid *leaf)
{
        struct sysctl_oid *nodes[CTL_MAXNAME];
        char buf[128];
        struct sbuf sb;
        int rc, i;

        (void)sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN | SBUF_INCLUDENUL);
        sbuf_set_drain(&sb, sbuf_printf_drain, NULL);

        sbuf_printf(&sb, "%s: can't re-use a leaf (", func);

        rc = sysctl_search_oid(nodes, leaf);
        if (rc > 0) {
                for (i = 0; i < rc; i++)
                        sbuf_printf(&sb, "%s%.*s", nodes[i]->oid_name,
                            i != (rc - 1), ".");
        } else {
                sbuf_cat(&sb, leaf->oid_name);
        }
        sbuf_cat(&sb, ")!\n");

        (void)sbuf_finish(&sb);
}

#ifdef SYSCTL_DEBUG
static int
sysctl_reuse_test(SYSCTL_HANDLER_ARGS)
{
        struct rm_priotracker tracker;

        SYSCTL_RLOCK(&tracker);
        sysctl_warn_reuse(__func__, oidp);
        SYSCTL_RUNLOCK(&tracker);
        return (0);
}
SYSCTL_PROC(_sysctl, OID_AUTO, reuse_test,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0, sysctl_reuse_test, "-",
    "");
#endif

void
sysctl_register_oid(struct sysctl_oid *oidp)
{
        struct sysctl_oid_list *parent = oidp->oid_parent;
        struct sysctl_oid *p, key;
        int oid_number;
        int timeout = 2;

        /*
         * First check if another oid with the same name already
         * exists in the parent's list.
         */
        SYSCTL_ASSERT_WLOCKED();
        p = sysctl_find_oidname(oidp->oid_name, parent);
        if (p != NULL) {
                if ((p->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        p->oid_refcnt++;
                        return;
                } else {
                        sysctl_warn_reuse(__func__, p);
                        return;
                }
        }
        /* get current OID number */
        oid_number = oidp->oid_number;

#if (OID_AUTO >= 0)
#error "OID_AUTO is expected to be a negative value"
#endif  
        /*
         * Any negative OID number qualifies as OID_AUTO. Valid OID
         * numbers should always be positive.
         *
         * NOTE: DO NOT change the starting value here, change it in
         * <sys/sysctl.h>, and make sure it is at least 256 to
         * accommodate e.g. net.inet.raw as a static sysctl node.
         */
        if (oid_number < 0) {
                static int newoid;

                /*
                 * By decrementing the next OID number we spend less
                 * time inserting the OIDs into a sorted list.
                 */
                if (--newoid < CTL_AUTO_START)
                        newoid = 0x7fffffff;

                oid_number = newoid;
        }

        /*
         * Insert the OID into the parent's list sorted by OID number.
         */
        key.oid_number = oid_number;
        p = RB_NFIND(sysctl_oid_list, parent, &key);
        while (p != NULL && oid_number == p->oid_number) {
                /* get the next valid OID number */
                if (oid_number < CTL_AUTO_START ||
                    oid_number == 0x7fffffff) {
                        /* wraparound - restart */
                        oid_number = CTL_AUTO_START;
                        /* don't loop forever */
                        if (!timeout--)
                                panic("sysctl: Out of OID numbers\n");
                        key.oid_number = oid_number;
                        p = RB_NFIND(sysctl_oid_list, parent, &key);
                        continue;
                }
                p = RB_NEXT(sysctl_oid_list, NULL, p);
                oid_number++;
        }
        /* check for non-auto OID number collision */
        if (oidp->oid_number >= 0 && oidp->oid_number < CTL_AUTO_START &&
            oid_number >= CTL_AUTO_START) {
                panic("sysctl: OID number(%d) is already in use for '%s'\n",
                    oidp->oid_number, oidp->oid_name);
        }
        /* update the OID number, if any */
        oidp->oid_number = oid_number;
        RB_INSERT(sysctl_oid_list, parent, oidp);

        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE &&
            (oidp->oid_kind & CTLFLAG_TUN) != 0 &&
            (oidp->oid_kind & CTLFLAG_NOFETCH) == 0) {
#ifdef VIMAGE
                /*
                 * Can fetch value multiple times for VNET loader tunables.
                 * Only fetch once for non-VNET loader tunables.
                 */
                if ((oidp->oid_kind & CTLFLAG_VNET) == 0)
#endif
                        oidp->oid_kind |= CTLFLAG_NOFETCH;
                /* try to fetch value from kernel environment */
                sysctl_load_tunable_by_oid_locked(oidp);
        }
}

void
sysctl_register_disabled_oid(struct sysctl_oid *oidp)
{

        /*
         * Mark the leaf as dormant if it's not to be immediately enabled.
         * We do not disable nodes as they can be shared between modules
         * and it is always safe to access a node.
         */
        KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
            ("internal flag is set in oid_kind"));
        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                oidp->oid_kind |= CTLFLAG_DORMANT;
        sysctl_register_oid(oidp);
}

void
sysctl_enable_oid(struct sysctl_oid *oidp)
{

        SYSCTL_ASSERT_WLOCKED();
        if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) == 0,
                    ("sysctl node is marked as dormant"));
                return;
        }
        KASSERT((oidp->oid_kind & CTLFLAG_DORMANT) != 0,
            ("enabling already enabled sysctl oid"));
        oidp->oid_kind &= ~CTLFLAG_DORMANT;
}

void
sysctl_unregister_oid(struct sysctl_oid *oidp)
{
        int error;

        SYSCTL_ASSERT_WLOCKED();
        if (oidp->oid_number == OID_AUTO) {
                error = EINVAL;
        } else {
                error = ENOENT;
                if (RB_REMOVE(sysctl_oid_list, oidp->oid_parent, oidp))
                        error = 0;
        }

        /* 
         * This can happen when a module fails to register and is
         * being unloaded afterwards.  It should not be a panic()
         * for normal use.
         */
        if (error) {
                printf("%s: failed(%d) to unregister sysctl(%s)\n",
                    __func__, error, oidp->oid_name);
        }
}

/* Initialize a new context to keep track of dynamically added sysctls. */
int
sysctl_ctx_init(struct sysctl_ctx_list *c)
{

        if (c == NULL) {
                return (EINVAL);
        }

        /*
         * No locking here, the caller is responsible for not adding
         * new nodes to a context until after this function has
         * returned.
         */
        TAILQ_INIT(c);
        return (0);
}

/* Free the context, and destroy all dynamic oids registered in this context */
int
sysctl_ctx_free(struct sysctl_ctx_list *clist)
{
        struct sysctl_ctx_entry *e, *e1;
        int error;

        error = 0;
        /*
         * First perform a "dry run" to check if it's ok to remove oids.
         * XXX FIXME
         * XXX This algorithm is a hack. But I don't know any
         * XXX better solution for now...
         */
        SYSCTL_WLOCK();
        TAILQ_FOREACH(e, clist, link) {
                error = sysctl_remove_oid_locked(e->entry, 0, 0);
                if (error)
                        break;
        }
        /*
         * Restore deregistered entries, either from the end,
         * or from the place where error occurred.
         * e contains the entry that was not unregistered
         */
        if (error)
                e1 = TAILQ_PREV(e, sysctl_ctx_list, link);
        else
                e1 = TAILQ_LAST(clist, sysctl_ctx_list);
        while (e1 != NULL) {
                sysctl_register_oid(e1->entry);
                e1 = TAILQ_PREV(e1, sysctl_ctx_list, link);
        }
        if (error) {
                SYSCTL_WUNLOCK();
                return(EBUSY);
        }
        /* Now really delete the entries */
        TAILQ_FOREACH_SAFE(e, clist, link, e1) {
                error = sysctl_remove_oid_locked(e->entry, 1, 0);
                if (error)
                        panic("sysctl_remove_oid: corrupt tree, entry: %s",
                            e->entry->oid_name);
                free(e, M_SYSCTLOID);
        }
        SYSCTL_WUNLOCK();
        TAILQ_INIT(clist);
        return (error);
}

/* Add an entry to the context */
struct sysctl_ctx_entry *
sysctl_ctx_entry_add(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
{
        struct sysctl_ctx_entry *e;

        SYSCTL_ASSERT_WLOCKED();
        if (clist == NULL || oidp == NULL)
                return(NULL);
        e = malloc(sizeof(struct sysctl_ctx_entry), M_SYSCTLOID, M_WAITOK);
        e->entry = oidp;
        TAILQ_INSERT_HEAD(clist, e, link);
        return (e);
}

/* Find an entry in the context */
struct sysctl_ctx_entry *
sysctl_ctx_entry_find(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
{
        struct sysctl_ctx_entry *e;

        SYSCTL_ASSERT_WLOCKED();
        if (clist == NULL || oidp == NULL)
                return(NULL);
        TAILQ_FOREACH(e, clist, link) {
                if (e->entry == oidp)
                        return(e);
        }
        return (e);
}

/*
 * Delete an entry from the context.
 * NOTE: this function doesn't free oidp! You have to remove it
 * with sysctl_remove_oid().
 */
int
sysctl_ctx_entry_del(struct sysctl_ctx_list *clist, struct sysctl_oid *oidp)
{
        struct sysctl_ctx_entry *e;

        if (clist == NULL || oidp == NULL)
                return (EINVAL);
        SYSCTL_WLOCK();
        e = sysctl_ctx_entry_find(clist, oidp);
        if (e != NULL) {
                TAILQ_REMOVE(clist, e, link);
                SYSCTL_WUNLOCK();
                free(e, M_SYSCTLOID);
                return (0);
        } else {
                SYSCTL_WUNLOCK();
                return (ENOENT);
        }
}

/*
 * Remove dynamically created sysctl trees.
 * oidp - top of the tree to be removed
 * del - if 0 - just deregister, otherwise free up entries as well
 * recurse - if != 0 traverse the subtree to be deleted
 */
int
sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse)
{
        int error;

        SYSCTL_WLOCK();
        error = sysctl_remove_oid_locked(oidp, del, recurse);
        SYSCTL_WUNLOCK();
        return (error);
}

int
sysctl_remove_name(struct sysctl_oid *parent, const char *name,
    int del, int recurse)
{
        struct sysctl_oid *p;
        int error;

        error = ENOENT;
        SYSCTL_WLOCK();
        p = sysctl_find_oidname(name, &parent->oid_children);
        if (p)
                error = sysctl_remove_oid_locked(p, del, recurse);
        SYSCTL_WUNLOCK();

        return (error);
}

/*
 * Duplicate the provided string, escaping any illegal characters.  The result
 * must be freed when no longer in use.
 *
 * The list of illegal characters is ".".
 */
static char*
sysctl_escape_name(const char* orig)
{
        int i, s = 0, d = 0, nillegals = 0;
        char *new;

        /* First count the number of illegal characters */
        for (i = 0; orig[i] != '\0'; i++) {
                if (orig[i] == '.')
                        nillegals++;
        }

        /* Allocate storage for new string */
        new = malloc(i + 2 * nillegals + 1, M_SYSCTLOID, M_WAITOK);

        /* Copy the name, escaping characters as we go */
        while (orig[s] != '\0') {
                if (orig[s] == '.') {
                        /* %25 is the hexadecimal representation of '.' */
                        new[d++] = '%';
                        new[d++] = '2';
                        new[d++] = '5';
                        s++;
                } else {
                        new[d++] = orig[s++];
                }
        }

        /* Finally, nul-terminate */
        new[d] = '\0';

        return (new);
}

static int
sysctl_remove_oid_locked(struct sysctl_oid *oidp, int del, int recurse)
{
        struct sysctl_oid *p, *tmp;
        int error;

        SYSCTL_ASSERT_WLOCKED();
        if (oidp == NULL)
                return(EINVAL);
        if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
                printf("Warning: can't remove non-dynamic nodes (%s)!\n",
                    oidp->oid_name);
                return (EINVAL);
        }
        /*
         * WARNING: normal method to do this should be through
         * sysctl_ctx_free(). Use recursing as the last resort
         * method to purge your sysctl tree of leftovers...
         * However, if some other code still references these nodes,
         * it will panic.
         */
        if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                if (oidp->oid_refcnt == 1) {
                        for(p = RB_MIN(sysctl_oid_list, &oidp->oid_children);
                            p != NULL; p = tmp) {
                                if (!recurse) {
                                        printf("Warning: failed attempt to "
                                            "remove oid %s with child %s\n",
                                            oidp->oid_name, p->oid_name);
                                        return (ENOTEMPTY);
                                }
                                tmp = RB_NEXT(sysctl_oid_list,
                                    &oidp->oid_children, p);
                                error = sysctl_remove_oid_locked(p, del,
                                    recurse);
                                if (error)
                                        return (error);
                        }
                }
        }
        if (oidp->oid_refcnt > 1 ) {
                oidp->oid_refcnt--;
        } else {
                if (oidp->oid_refcnt == 0) {
                        printf("Warning: bad oid_refcnt=%u (%s)!\n",
                                oidp->oid_refcnt, oidp->oid_name);
                        return (EINVAL);
                }
                sysctl_unregister_oid(oidp);
                if (del) {
                        /*
                         * Wait for all threads running the handler to drain.
                         * This preserves the previous behavior when the
                         * sysctl lock was held across a handler invocation,
                         * and is necessary for module unload correctness.
                         */
                        while (oidp->oid_running > 0) {
                                oidp->oid_kind |= CTLFLAG_DYING;
                                SYSCTL_SLEEP(&oidp->oid_running, "oidrm", 0);
                        }
                        if (oidp->oid_descr)
                                free(__DECONST(char *, oidp->oid_descr),
                                    M_SYSCTLOID);
                        if (oidp->oid_label)
                                free(__DECONST(char *, oidp->oid_label),
                                    M_SYSCTLOID);
                        free(__DECONST(char *, oidp->oid_name), M_SYSCTLOID);
                        free(oidp, M_SYSCTLOID);
                }
        }
        return (0);
}
/*
 * Create new sysctls at run time.
 * clist may point to a valid context initialized with sysctl_ctx_init().
 */
struct sysctl_oid *
sysctl_add_oid(struct sysctl_ctx_list *clist, struct sysctl_oid_list *parent,
        int number, const char *name, int kind, void *arg1, intmax_t arg2,
        int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr,
        const char *label)
{
        struct sysctl_oid *oidp;
        char *escaped;

        /* You have to hook up somewhere.. */
        if (parent == NULL)
                return(NULL);
        escaped = sysctl_escape_name(name);
        /* Check if the node already exists, otherwise create it */
        SYSCTL_WLOCK();
        oidp = sysctl_find_oidname(escaped, parent);
        if (oidp != NULL) {
                free(escaped, M_SYSCTLOID);
                if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        oidp->oid_refcnt++;
                        /* Update the context */
                        if (clist != NULL)
                                sysctl_ctx_entry_add(clist, oidp);
                        SYSCTL_WUNLOCK();
                        return (oidp);
                } else {
                        sysctl_warn_reuse(__func__, oidp);
                        SYSCTL_WUNLOCK();
                        return (NULL);
                }
        }
        oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
        oidp->oid_parent = parent;
        RB_INIT(&oidp->oid_children);
        oidp->oid_number = number;
        oidp->oid_refcnt = 1;
        oidp->oid_name = escaped;
        oidp->oid_handler = handler;
        oidp->oid_kind = CTLFLAG_DYN | kind;
        oidp->oid_arg1 = arg1;
        oidp->oid_arg2 = arg2;
        oidp->oid_fmt = fmt;
        if (descr != NULL)
                oidp->oid_descr = strdup(descr, M_SYSCTLOID);
        if (label != NULL)
                oidp->oid_label = strdup(label, M_SYSCTLOID);
        /* Update the context, if used */
        if (clist != NULL)
                sysctl_ctx_entry_add(clist, oidp);
        /* Register this oid */
        sysctl_register_oid(oidp);
        SYSCTL_WUNLOCK();
        return (oidp);
}

/*
 * Rename an existing oid.
 */
void
sysctl_rename_oid(struct sysctl_oid *oidp, const char *name)
{
        char *newname;
        char *oldname;

        newname = strdup(name, M_SYSCTLOID);
        SYSCTL_WLOCK();
        oldname = __DECONST(char *, oidp->oid_name);
        oidp->oid_name = newname;
        SYSCTL_WUNLOCK();
        free(oldname, M_SYSCTLOID);
}

/*
 * Reparent an existing oid.
 */
int
sysctl_move_oid(struct sysctl_oid *oid, struct sysctl_oid_list *parent)
{
        struct sysctl_oid *oidp;

        SYSCTL_WLOCK();
        if (oid->oid_parent == parent) {
                SYSCTL_WUNLOCK();
                return (0);
        }
        oidp = sysctl_find_oidname(oid->oid_name, parent);
        if (oidp != NULL) {
                SYSCTL_WUNLOCK();
                return (EEXIST);
        }
        sysctl_unregister_oid(oid);
        oid->oid_parent = parent;
        oid->oid_number = OID_AUTO;
        sysctl_register_oid(oid);
        SYSCTL_WUNLOCK();
        return (0);
}

/*
 * Register the kernel's oids on startup.
 */
SET_DECLARE(sysctl_set, struct sysctl_oid);

static void
sysctl_register_all(void *arg)
{
        struct sysctl_oid **oidp;

        sx_init(&sysctlmemlock, "sysctl mem");
        sx_init(&sysctlstringlock, "sysctl string handler");
        SYSCTL_INIT();
        SYSCTL_WLOCK();
        SET_FOREACH(oidp, sysctl_set)
                sysctl_register_oid(*oidp);
        SYSCTL_WUNLOCK();
}
SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_FIRST, sysctl_register_all, NULL);

#ifdef VIMAGE
static void
sysctl_setenv_vnet(void *arg __unused, const char *name)
{
        struct sysctl_oid *oidp;
        int oid[CTL_MAXNAME];
        int error, nlen;

        SYSCTL_WLOCK();
        error = name2oid(name, oid, &nlen, &oidp);
        if (error)
                goto out;

        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE &&
            (oidp->oid_kind & CTLFLAG_VNET) != 0 &&
            (oidp->oid_kind & CTLFLAG_TUN) != 0 &&
            (oidp->oid_kind & CTLFLAG_NOFETCH) == 0) {
                /* Update value from kernel environment */
                sysctl_load_tunable_by_oid_locked(oidp);
        }
out:
        SYSCTL_WUNLOCK();
}

static void
sysctl_unsetenv_vnet(void *arg __unused, const char *name)
{
        struct sysctl_oid *oidp;
        int oid[CTL_MAXNAME];
        int error, nlen;

        SYSCTL_WLOCK();
        /*
         * The setenv / unsetenv event handlers are invoked by kern_setenv() /
         * kern_unsetenv() without exclusive locks. It is rare but still possible
         * that the invoke order of event handlers is different from that of
         * kern_setenv() and kern_unsetenv().
         * Re-check environment variable string to make sure it is unset.
         */
        if (testenv(name))
                goto out;
        error = name2oid(name, oid, &nlen, &oidp);
        if (error)
                goto out;

        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE &&
            (oidp->oid_kind & CTLFLAG_VNET) != 0 &&
            (oidp->oid_kind & CTLFLAG_TUN) != 0 &&
            (oidp->oid_kind & CTLFLAG_NOFETCH) == 0) {
                size_t size;

                switch (oidp->oid_kind & CTLTYPE) {
                case CTLTYPE_INT:
                case CTLTYPE_UINT:
                        size = sizeof(int);
                        break;
                case CTLTYPE_LONG:
                case CTLTYPE_ULONG:
                        size = sizeof(long);
                        break;
                case CTLTYPE_S8:
                case CTLTYPE_U8:
                        size = sizeof(int8_t);
                        break;
                case CTLTYPE_S16:
                case CTLTYPE_U16:
                        size = sizeof(int16_t);
                        break;
                case CTLTYPE_S32:
                case CTLTYPE_U32:
                        size = sizeof(int32_t);
                        break;
                case CTLTYPE_S64:
                case CTLTYPE_U64:
                        size = sizeof(int64_t);
                        break;
                case CTLTYPE_STRING:
                        MPASS(oidp->oid_arg2 > 0);
                        size = oidp->oid_arg2;
                        break;
                default:
                        goto out;
                }
                vnet_restore_init(oidp->oid_arg1, size);
        }
out:
        SYSCTL_WUNLOCK();
}

/*
 * Register the kernel's setenv / unsetenv events.
 */
EVENTHANDLER_DEFINE(setenv, sysctl_setenv_vnet, NULL, EVENTHANDLER_PRI_ANY);
EVENTHANDLER_DEFINE(unsetenv, sysctl_unsetenv_vnet, NULL, EVENTHANDLER_PRI_ANY);
#endif

/*
 * "Staff-functions"
 *
 * These functions implement a presently undocumented interface 
 * used by the sysctl program to walk the tree, and get the type
 * so it can print the value.
 * This interface is under work and consideration, and should probably
 * be killed with a big axe by the first person who can find the time.
 * (be aware though, that the proper interface isn't as obvious as it
 * may seem, there are various conflicting requirements.
 *
 * {CTL_SYSCTL, CTL_SYSCTL_DEBUG}               printf the entire MIB-tree.
 * {CTL_SYSCTL, CTL_SYSCTL_NAME, ...}           return the name of the "..."
 *                                              OID.
 * {CTL_SYSCTL, CTL_SYSCTL_NEXT, ...}           return the next OID, honoring
 *                                              CTLFLAG_SKIP.
 * {CTL_SYSCTL, CTL_SYSCTL_NAME2OID}            return the OID of the name in
 *                                              "new"
 * {CTL_SYSCTL, CTL_SYSCTL_OIDFMT, ...}         return the kind & format info
 *                                              for the "..." OID.
 * {CTL_SYSCTL, CTL_SYSCTL_OIDDESCR, ...}       return the description of the
 *                                              "..." OID.
 * {CTL_SYSCTL, CTL_SYSCTL_OIDLABEL, ...}       return the aggregation label of
 *                                              the "..." OID.
 * {CTL_SYSCTL, CTL_SYSCTL_NEXTNOSKIP, ...}     return the next OID, ignoring
 *                                              CTLFLAG_SKIP.
 */

#ifdef SYSCTL_DEBUG
static void
sysctl_sysctl_debug_dump_node(struct sysctl_oid_list *l, int i)
{
        int k;
        struct sysctl_oid *oidp;

        SYSCTL_ASSERT_LOCKED();
        SYSCTL_FOREACH(oidp, l) {
                for (k=0; k<i; k++)
                        printf(" ");

                printf("%d %s ", oidp->oid_number, oidp->oid_name);

                printf("%c%c",
                        oidp->oid_kind & CTLFLAG_RD ? 'R':' ',
                        oidp->oid_kind & CTLFLAG_WR ? 'W':' ');

                if (oidp->oid_handler)
                        printf(" *Handler");

                switch (oidp->oid_kind & CTLTYPE) {
                        case CTLTYPE_NODE:
                                printf(" Node\n");
                                if (!oidp->oid_handler) {
                                        sysctl_sysctl_debug_dump_node(
                                            SYSCTL_CHILDREN(oidp), i + 2);
                                }
                                break;
                        case CTLTYPE_INT:    printf(" Int\n"); break;
                        case CTLTYPE_UINT:   printf(" u_int\n"); break;
                        case CTLTYPE_LONG:   printf(" Long\n"); break;
                        case CTLTYPE_ULONG:  printf(" u_long\n"); break;
                        case CTLTYPE_STRING: printf(" String\n"); break;
                        case CTLTYPE_S8:     printf(" int8_t\n"); break;
                        case CTLTYPE_S16:    printf(" int16_t\n"); break;
                        case CTLTYPE_S32:    printf(" int32_t\n"); break;
                        case CTLTYPE_S64:    printf(" int64_t\n"); break;
                        case CTLTYPE_U8:     printf(" uint8_t\n"); break;
                        case CTLTYPE_U16:    printf(" uint16_t\n"); break;
                        case CTLTYPE_U32:    printf(" uint32_t\n"); break;
                        case CTLTYPE_U64:    printf(" uint64_t\n"); break;
                        case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
                        default:             printf("\n");
                }
        }
}

static int
sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
{
        struct rm_priotracker tracker;
        int error;

        error = priv_check(req->td, PRIV_SYSCTL_DEBUG);
        if (error)
                return (error);
        SYSCTL_RLOCK(&tracker);
        sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
        SYSCTL_RUNLOCK(&tracker);
        return (ENOENT);
}

SYSCTL_PROC(_sysctl, CTL_SYSCTL_DEBUG, debug, CTLTYPE_STRING | CTLFLAG_RD |
    CTLFLAG_MPSAFE, 0, 0, sysctl_sysctl_debug, "-", "");
#endif

static int
sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int error;
        struct sysctl_oid *oid, key;
        struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
        struct rm_priotracker tracker;
        char buf[10];

        error = sysctl_wire_old_buffer(req, 0);
        if (error)
                return (error);

        SYSCTL_RLOCK(&tracker);
        while (namelen) {
                if (!lsp) {
                        snprintf(buf,sizeof(buf),"%d",*name);
                        if (req->oldidx)
                                error = SYSCTL_OUT(req, ".", 1);
                        if (!error)
                                error = SYSCTL_OUT(req, buf, strlen(buf));
                        if (error)
                                goto out;
                        namelen--;
                        name++;
                        continue;
                }
                lsp2 = NULL;
                key.oid_number = *name;
                oid = RB_FIND(sysctl_oid_list, lsp, &key);
                if (oid) {
                        if (req->oldidx)
                                error = SYSCTL_OUT(req, ".", 1);
                        if (!error)
                                error = SYSCTL_OUT(req, oid->oid_name,
                                        strlen(oid->oid_name));
                        if (error)
                                goto out;

                        namelen--;
                        name++;

                        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE &&
                                !oid->oid_handler)
                                lsp2 = SYSCTL_CHILDREN(oid);
                }
                lsp = lsp2;
        }
        error = SYSCTL_OUT(req, "", 1);
 out:
        SYSCTL_RUNLOCK(&tracker);
        return (error);
}

/*
 * XXXRW/JA: Shouldn't return name data for nodes that we don't permit in
 * capability mode.
 */
static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NAME, name, CTLFLAG_RD |
    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_name, "");

enum sysctl_iter_action {
        ITER_SIBLINGS,  /* Not matched, continue iterating siblings */
        ITER_CHILDREN,  /* Node has children we need to iterate over them */
        ITER_FOUND,     /* Matching node was found */
};

/*
 * Tries to find the next node for @name and @namelen.
 *
 * Returns next action to take. 
 */
static enum sysctl_iter_action
sysctl_sysctl_next_node(struct sysctl_oid *oidp, int *name, unsigned int namelen,
    bool honor_skip)
{

        if ((oidp->oid_kind & CTLFLAG_DORMANT) != 0)
                return (ITER_SIBLINGS);

        if (honor_skip && (oidp->oid_kind & CTLFLAG_SKIP) != 0)
                return (ITER_SIBLINGS);

        if (namelen == 0) {
                /*
                 * We have reached a node with a full name match and are
                 * looking for the next oid in its children.
                 *
                 * For CTL_SYSCTL_NEXTNOSKIP we are done.
                 *
                 * For CTL_SYSCTL_NEXT we skip CTLTYPE_NODE (unless it
                 * has a handler) and move on to the children.
                 */
                if (!honor_skip)
                        return (ITER_FOUND);
                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
                        return (ITER_FOUND);
                /* If node does not have an iterator, treat it as leaf */
                if (oidp->oid_handler) 
                        return (ITER_FOUND);

                /* Report oid as a node to iterate */
                return (ITER_CHILDREN);
        }

        /*
         * No match yet. Continue seeking the given name.
         *
         * We are iterating in order by oid_number, so skip oids lower
         * than the one we are looking for.
         *
         * When the current oid_number is higher than the one we seek,
         * that means we have reached the next oid in the sequence and
         * should return it.
         *
         * If the oid_number matches the name at this level then we
         * have to find a node to continue searching at the next level.
         */
        if (oidp->oid_number < *name)
                return (ITER_SIBLINGS);
        if (oidp->oid_number > *name) {
                /*
                 * We have reached the next oid.
                 *
                 * For CTL_SYSCTL_NEXTNOSKIP we are done.
                 *
                 * For CTL_SYSCTL_NEXT we skip CTLTYPE_NODE (unless it
                 * has a handler) and move on to the children.
                 */
                if (!honor_skip)
                        return (ITER_FOUND);
                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                        return (ITER_FOUND);
                /* If node does not have an iterator, treat it as leaf */
                if (oidp->oid_handler)
                        return (ITER_FOUND);
                return (ITER_CHILDREN);
        }

        /* match at a current level */
        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                return (ITER_SIBLINGS);
        if (oidp->oid_handler)
                return (ITER_SIBLINGS);

        return (ITER_CHILDREN);
}

/*
 * Recursively walk the sysctl subtree at lsp until we find the given name.
 * Returns true and fills in next oid data in @next and @len if oid is found.
 */
static bool
sysctl_sysctl_next_action(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
    int *next, int *len, int level, bool honor_skip)
{
        struct sysctl_oid_list *next_lsp;
        struct sysctl_oid *oidp = NULL, key;
        bool success = false;
        enum sysctl_iter_action action;

        SYSCTL_ASSERT_LOCKED();
        /*
         * Start the search at the requested oid.  But if not found, then scan
         * through all children.
         */
        if (namelen > 0) {
                key.oid_number = *name;
                oidp = RB_FIND(sysctl_oid_list, lsp, &key);
        }
        if (!oidp)
                oidp = RB_MIN(sysctl_oid_list, lsp);
        for(; oidp != NULL; oidp = RB_NEXT(sysctl_oid_list, lsp, oidp)) {
                action = sysctl_sysctl_next_node(oidp, name, namelen,
                    honor_skip);
                if (action == ITER_SIBLINGS)
                        continue;
                if (action == ITER_FOUND) {
                        success = true;
                        break;
                }
                KASSERT((action== ITER_CHILDREN), ("ret(%d)!=ITER_CHILDREN", action));

                next_lsp = SYSCTL_CHILDREN(oidp);
                if (namelen == 0) {
                        success = sysctl_sysctl_next_action(next_lsp, NULL, 0,
                            next + 1, len, level + 1, honor_skip);
                } else {
                        success = sysctl_sysctl_next_action(next_lsp, name + 1,
                            namelen - 1, next + 1, len, level + 1, honor_skip);
                        if (!success) {

                                /*
                                 * We maintain the invariant that current node oid
                                 * is >= the oid provided in @name.
                                 * As there are no usable children at this node,
                                 *  current node oid is strictly > than the requested
                                 *  oid.
                                 * Hence, reduce namelen to 0 to allow for picking first
                                 *  nodes/leafs in the next node in list.
                                 */
                                namelen = 0;
                        }
                }
                if (success)
                        break;
        }

        if (success) {
                *next = oidp->oid_number;
                if (level > *len)
                        *len = level;
        }

        return (success);
}

static int
sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int len, error;
        bool success;
        struct sysctl_oid_list *lsp = &sysctl__children;
        struct rm_priotracker tracker;
        int next[CTL_MAXNAME];

        len = 0;
        SYSCTL_RLOCK(&tracker);
        success = sysctl_sysctl_next_action(lsp, name, namelen, next, &len, 1,
            oidp->oid_number == CTL_SYSCTL_NEXT);
        SYSCTL_RUNLOCK(&tracker);
        if (!success)
                return (ENOENT);
        error = SYSCTL_OUT(req, next, len * sizeof (int));
        return (error);
}

/*
 * XXXRW/JA: Shouldn't return next data for nodes that we don't permit in
 * capability mode.
 */
static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NEXT, next, CTLFLAG_RD |
    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_next, "");

static SYSCTL_NODE(_sysctl, CTL_SYSCTL_NEXTNOSKIP, nextnoskip, CTLFLAG_RD |
    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_next, "");

static int
name2oid(const char *name, int *oid, int *len, struct sysctl_oid **oidpp)
{
        struct sysctl_oid *oidp;
        struct sysctl_oid_list *lsp = &sysctl__children;
        const char *n;

        SYSCTL_ASSERT_LOCKED();

        for (*len = 0; *len < CTL_MAXNAME;) {
                n = strchrnul(name, '.');
                oidp = sysctl_find_oidnamelen(name, n - name, lsp);
                if (oidp == NULL)
                        return (ENOENT);
                *oid++ = oidp->oid_number;
                (*len)++;

                name = n;
                if (*name == '.')
                        name++;
                if (*name == '\0') {
                        if (oidpp)
                                *oidpp = oidp;
                        return (0);
                }

                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                        break;

                if (oidp->oid_handler)
                        break;

                lsp = SYSCTL_CHILDREN(oidp);
        }
        return (ENOENT);
}

static int
sysctl_sysctl_name2oid(SYSCTL_HANDLER_ARGS)
{
        char *p;
        int error, oid[CTL_MAXNAME], len = 0;
        struct sysctl_oid *op = NULL;
        struct rm_priotracker tracker;
        char buf[32];

        if (!req->newlen) 
                return (ENOENT);
        if (req->newlen >= MAXPATHLEN)  /* XXX arbitrary, undocumented */
                return (ENAMETOOLONG);

        p = buf;
        if (req->newlen >= sizeof(buf))
                p = malloc(req->newlen+1, M_SYSCTL, M_WAITOK);

        error = SYSCTL_IN(req, p, req->newlen);
        if (error) {
                if (p != buf)
                        free(p, M_SYSCTL);
                return (error);
        }

        p [req->newlen] = '\0';

        SYSCTL_RLOCK(&tracker);
        error = name2oid(p, oid, &len, &op);
        SYSCTL_RUNLOCK(&tracker);

        if (p != buf)
                free(p, M_SYSCTL);

        if (error)
                return (error);

        error = SYSCTL_OUT(req, oid, len * sizeof *oid);
        return (error);
}

/*
 * XXXRW/JA: Shouldn't return name2oid data for nodes that we don't permit in
 * capability mode.
 */
SYSCTL_PROC(_sysctl, CTL_SYSCTL_NAME2OID, name2oid, CTLTYPE_INT | CTLFLAG_RW |
    CTLFLAG_ANYBODY | CTLFLAG_MPSAFE | CTLFLAG_CAPRW, 0, 0,
    sysctl_sysctl_name2oid, "I", "");

static int
sysctl_sysctl_oidfmt(SYSCTL_HANDLER_ARGS)
{
        struct sysctl_oid *oid;
        struct rm_priotracker tracker;
        int error;

        error = sysctl_wire_old_buffer(req, 0);
        if (error)
                return (error);

        SYSCTL_RLOCK(&tracker);
        error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
        if (error)
                goto out;

        if (oid->oid_fmt == NULL) {
                error = ENOENT;
                goto out;
        }
        error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
        if (error)
                goto out;
        error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
 out:
        SYSCTL_RUNLOCK(&tracker);
        return (error);
}

static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDFMT, oidfmt, CTLFLAG_RD |
    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidfmt, "");

static int
sysctl_sysctl_oiddescr(SYSCTL_HANDLER_ARGS)
{
        struct sysctl_oid *oid;
        struct rm_priotracker tracker;
        int error;

        error = sysctl_wire_old_buffer(req, 0);
        if (error)
                return (error);

        SYSCTL_RLOCK(&tracker);
        error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
        if (error)
                goto out;

        if (oid->oid_descr == NULL) {
                error = ENOENT;
                goto out;
        }
        error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
 out:
        SYSCTL_RUNLOCK(&tracker);
        return (error);
}

static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDDESCR, oiddescr, CTLFLAG_RD |
    CTLFLAG_MPSAFE|CTLFLAG_CAPRD, sysctl_sysctl_oiddescr, "");

static int
sysctl_sysctl_oidlabel(SYSCTL_HANDLER_ARGS)
{
        struct sysctl_oid *oid;
        struct rm_priotracker tracker;
        int error;

        error = sysctl_wire_old_buffer(req, 0);
        if (error)
                return (error);

        SYSCTL_RLOCK(&tracker);
        error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
        if (error)
                goto out;

        if (oid->oid_label == NULL) {
                error = ENOENT;
                goto out;
        }
        error = SYSCTL_OUT(req, oid->oid_label, strlen(oid->oid_label) + 1);
 out:
        SYSCTL_RUNLOCK(&tracker);
        return (error);
}

static SYSCTL_NODE(_sysctl, CTL_SYSCTL_OIDLABEL, oidlabel, CTLFLAG_RD |
    CTLFLAG_MPSAFE | CTLFLAG_CAPRD, sysctl_sysctl_oidlabel, "");

/*
 * Default "handler" functions.
 */

/*
 * Handle a bool.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_bool(SYSCTL_HANDLER_ARGS)
{
        int error;
        uint8_t temp;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                temp = *(bool *)arg1 ? 1 : 0;
        else
                temp = arg2 ? 1 : 0;

        /*
         * In order to support backwards-compatible conversion of integer knobs
         * that are used as booleans to true boolean knobs, whose internal state
         * is stored as a 'bool' and not an 'int', if exactly 4 bytes remain in
         * the output buffer, we assume that the caller expected an 'int'
         * instead of a 'uint8_t'.
         */
        if (req->oldlen - req->oldidx == sizeof(int)) {
                int temp_int = temp;

                error = SYSCTL_OUT(req, &temp_int, sizeof(temp_int));
        } else
                error = SYSCTL_OUT(req, &temp, sizeof(temp));
        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else {
                /*
                 * Conversely, if the input buffer has exactly 4 bytes to read,
                 * use them all to produce a bool.
                 */
                if (req->newlen - req->newidx == sizeof(int)) {
                        int temp_int;

                        error = SYSCTL_IN(req, &temp_int, sizeof(temp_int));
                        if (error == 0)
                                *(bool *)arg1 = temp_int != 0 ? 1 : 0;
                } else {
                        error = SYSCTL_IN(req, &temp, sizeof(temp));
                        if (error == 0)
                                *(bool *)arg1 = temp != 0 ? 1 : 0;
                }
        }
        return (error);
}

/*
 * Handle an int8_t, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_8(SYSCTL_HANDLER_ARGS)
{
        int8_t tmpout;
        int error = 0;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmpout = *(int8_t *)arg1;
        else
                tmpout = arg2;
        error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(tmpout));
        return (error);
}

/*
 * Handle an int16_t, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_16(SYSCTL_HANDLER_ARGS)
{
        int16_t tmpout;
        int error = 0;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmpout = *(int16_t *)arg1;
        else
                tmpout = arg2;
        error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(tmpout));
        return (error);
}

/*
 * Handle an int32_t, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_32(SYSCTL_HANDLER_ARGS)
{
        int32_t tmpout;
        int error = 0;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmpout = *(int32_t *)arg1;
        else
                tmpout = arg2;
        error = SYSCTL_OUT(req, &tmpout, sizeof(tmpout));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(tmpout));
        return (error);
}

/*
 * Handle an int, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_int(SYSCTL_HANDLER_ARGS)
{
        int tmpout, error = 0;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmpout = *(int *)arg1;
        else
                tmpout = arg2;
        error = SYSCTL_OUT(req, &tmpout, sizeof(int));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(int));
        return (error);
}

/*
 * Based on sysctl_handle_int() convert milliseconds into ticks.
 * Note: this is used by TCP.
 */

int
sysctl_msec_to_ticks(SYSCTL_HANDLER_ARGS)
{
        int error, s, tt;

        tt = *(int *)arg1;
        s = (int)((int64_t)tt * 1000 / hz);

        error = sysctl_handle_int(oidp, &s, 0, req);
        if (error || !req->newptr)
                return (error);

        tt = (int)((int64_t)s * hz / 1000);
        if (tt < 1)
                return (EINVAL);

        *(int *)arg1 = tt;
        return (0);
}

/*
 * Handle a long, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */

int
sysctl_handle_long(SYSCTL_HANDLER_ARGS)
{
        int error = 0;
        long tmplong;
#ifdef SCTL_MASK32
        int tmpint;
#endif

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmplong = *(long *)arg1;
        else
                tmplong = arg2;
#ifdef SCTL_MASK32
        if (req->flags & SCTL_MASK32) {
                tmpint = tmplong;
                error = SYSCTL_OUT(req, &tmpint, sizeof(int));
        } else
#endif
                error = SYSCTL_OUT(req, &tmplong, sizeof(long));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
#ifdef SCTL_MASK32
        else if (req->flags & SCTL_MASK32) {
                error = SYSCTL_IN(req, &tmpint, sizeof(int));
                *(long *)arg1 = (long)tmpint;
        }
#endif
        else
                error = SYSCTL_IN(req, arg1, sizeof(long));
        return (error);
}

/*
 * Handle a 64 bit int, signed or unsigned.
 * Two cases:
 *     a variable:  point arg1 at it.
 *     a constant:  pass it in arg2.
 */
int
sysctl_handle_64(SYSCTL_HANDLER_ARGS)
{
        int error = 0;
        uint64_t tmpout;

        /*
         * Attempt to get a coherent snapshot by making a copy of the data.
         */
        if (arg1)
                tmpout = *(uint64_t *)arg1;
        else
                tmpout = arg2;
        error = SYSCTL_OUT(req, &tmpout, sizeof(uint64_t));

        if (error || !req->newptr)
                return (error);

        if (!arg1)
                error = EPERM;
        else
                error = SYSCTL_IN(req, arg1, sizeof(uint64_t));
        return (error);
}

/*
 * Handle our generic '\0' terminated 'C' string.
 * Two cases:
 *      a variable string:  point arg1 at it, arg2 is max length.
 *      a constant string:  point arg1 at it, arg2 is zero.
 */

int
sysctl_handle_string(SYSCTL_HANDLER_ARGS)
{
        char *tmparg;
        int error = 0;

        /*
         * If the sysctl isn't writable and isn't a preallocated tunable that
         * can be modified by kenv(2), microoptimise and treat it as a
         * read-only string.
         * A zero-length buffer indicates a fixed size read-only
         * string.  In ddb, don't worry about trying to make a malloced
         * snapshot.
         */
        if ((oidp->oid_kind & (CTLFLAG_WR | CTLFLAG_TUN)) == 0 ||
            arg2 == 0 || kdb_active) {
                size_t outlen;

                if (arg2 == 0)
                        outlen = arg2 = strlen(arg1) + 1;
                else
                        outlen = strnlen(arg1, arg2 - 1) + 1;

                tmparg = req->oldptr != NULL ? arg1 : NULL;
                error = SYSCTL_OUT(req, tmparg, outlen);
        } else {
                size_t outlen;

                if (req->oldptr != NULL) {
                        tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);
                        sx_slock(&sysctlstringlock);
                        memcpy(tmparg, arg1, arg2);
                        sx_sunlock(&sysctlstringlock);
                        outlen = strnlen(tmparg, arg2 - 1) + 1;
                } else {
                        tmparg = NULL;
                        sx_slock(&sysctlstringlock);
                        outlen = strnlen(arg1, arg2 - 1) + 1;
                        sx_sunlock(&sysctlstringlock);
                }
                error = SYSCTL_OUT(req, tmparg, outlen);
                free(tmparg, M_SYSCTLTMP);
        }
        if (error || !req->newptr)
                return (error);

        if (req->newlen - req->newidx >= arg2 ||
            req->newlen - req->newidx < 0) {
                error = EINVAL;
        } else if (req->newlen - req->newidx == 0) {
                sx_xlock(&sysctlstringlock);
                ((char *)arg1)[0] = '\0';
                sx_xunlock(&sysctlstringlock);
        } else if (req->newfunc == sysctl_new_kernel) {
                arg2 = req->newlen - req->newidx;
                sx_xlock(&sysctlstringlock);
                error = SYSCTL_IN(req, arg1, arg2);
                if (error == 0) {
                        ((char *)arg1)[arg2] = '\0';
                        req->newidx += arg2;
                }
                sx_xunlock(&sysctlstringlock);
        } else {
                arg2 = req->newlen - req->newidx;
                tmparg = malloc(arg2, M_SYSCTLTMP, M_WAITOK);

                error = SYSCTL_IN(req, tmparg, arg2);
                if (error) {
                        free(tmparg, M_SYSCTLTMP);
                        return (error);
                }

                sx_xlock(&sysctlstringlock);
                memcpy(arg1, tmparg, arg2);
                ((char *)arg1)[arg2] = '\0';
                sx_xunlock(&sysctlstringlock);
                free(tmparg, M_SYSCTLTMP);
                req->newidx += arg2;
        }
        return (error);
}

/*
 * Handle any kind of opaque data.
 * arg1 points to it, arg2 is the size.
 */

int
sysctl_handle_opaque(SYSCTL_HANDLER_ARGS)
{
        int error, tries;
        u_int generation;
        struct sysctl_req req2;

        /*
         * Attempt to get a coherent snapshot, by using the thread
         * pre-emption counter updated from within mi_switch() to
         * determine if we were pre-empted during a bcopy() or
         * copyout(). Make 3 attempts at doing this before giving up.
         * If we encounter an error, stop immediately.
         */
        tries = 0;
        req2 = *req;
retry:
        generation = curthread->td_generation;
        error = SYSCTL_OUT(req, arg1, arg2);
        if (error)
                return (error);
        tries++;
        if (generation != curthread->td_generation && tries < 3) {
                *req = req2;
                goto retry;
        }

        error = SYSCTL_IN(req, arg1, arg2);

        return (error);
}

/*
 * Based on sysctl_handle_64() convert microseconds to a sbintime.
 */
int
sysctl_usec_to_sbintime(SYSCTL_HANDLER_ARGS)
{
        int error;
        int64_t usec;

        usec = sbttous(*(sbintime_t *)arg1);

        error = sysctl_handle_64(oidp, &usec, 0, req);
        if (error || !req->newptr)
                return (error);

        *(sbintime_t *)arg1 = ustosbt(usec);

        return (0);
}

/*
 * Based on sysctl_handle_64() convert milliseconds to a sbintime.
 */
int
sysctl_msec_to_sbintime(SYSCTL_HANDLER_ARGS)
{
        int error;
        int64_t msec;

        msec = sbttoms(*(sbintime_t *)arg1);

        error = sysctl_handle_64(oidp, &msec, 0, req);
        if (error || !req->newptr)
                return (error);

        *(sbintime_t *)arg1 = mstosbt(msec);

        return (0);
}

/*
 * Convert seconds to a struct timeval.  Intended for use with
 * intervals and thus does not permit negative seconds.
 */
int
sysctl_sec_to_timeval(SYSCTL_HANDLER_ARGS)
{
        struct timeval *tv;
        int error, secs;

        tv = arg1;
        secs = tv->tv_sec;

        error = sysctl_handle_int(oidp, &secs, 0, req);
        if (error || req->newptr == NULL)
                return (error);

        if (secs < 0)
                return (EINVAL);
        tv->tv_sec = secs;

        return (0);
}

/*
 * Transfer functions to/from kernel space.
 * XXX: rather untested at this point
 */
static int
sysctl_old_kernel(struct sysctl_req *req, const void *p, size_t l)
{
        size_t i = 0;

        if (req->oldptr) {
                i = l;
                if (req->oldlen <= req->oldidx)
                        i = 0;
                else
                        if (i > req->oldlen - req->oldidx)
                                i = req->oldlen - req->oldidx;
                if (i > 0)
                        bcopy(p, (char *)req->oldptr + req->oldidx, i);
        }
        req->oldidx += l;
        if (req->oldptr && i != l)
                return (ENOMEM);
        return (0);
}

static int
sysctl_new_kernel(struct sysctl_req *req, void *p, size_t l)
{
        if (!req->newptr)
                return (0);
        if (req->newlen - req->newidx < l)
                return (EINVAL);
        bcopy((const char *)req->newptr + req->newidx, p, l);
        req->newidx += l;
        return (0);
}

int
kernel_sysctl(struct thread *td, int *name, u_int namelen, void *old,
    size_t *oldlenp, void *new, size_t newlen, size_t *retval, int flags)
{
        int error = 0;
        struct sysctl_req req;

        bzero(&req, sizeof req);

        req.td = td;
        req.flags = flags;

        if (oldlenp) {
                req.oldlen = *oldlenp;
        }
        req.validlen = req.oldlen;

        if (old) {
                req.oldptr= old;
        }

        if (new != NULL) {
                req.newlen = newlen;
                req.newptr = new;
        }

        req.oldfunc = sysctl_old_kernel;
        req.newfunc = sysctl_new_kernel;
        req.lock = REQ_UNWIRED;

        error = sysctl_root(0, name, namelen, &req);

        if (req.lock == REQ_WIRED && req.validlen > 0)
                vsunlock(req.oldptr, req.validlen);

        if (error && error != ENOMEM)
                return (error);

        if (retval) {
                if (req.oldptr && req.oldidx > req.validlen)
                        *retval = req.validlen;
                else
                        *retval = req.oldidx;
        }
        return (error);
}

int
kernel_sysctlbyname(struct thread *td, char *name, void *old, size_t *oldlenp,
    void *new, size_t newlen, size_t *retval, int flags)
{
        int oid[CTL_MAXNAME];
        size_t oidlen, plen;
        int error;

        oid[0] = CTL_SYSCTL;
        oid[1] = CTL_SYSCTL_NAME2OID;
        oidlen = sizeof(oid);

        error = kernel_sysctl(td, oid, 2, oid, &oidlen,
            (void *)name, strlen(name), &plen, flags);
        if (error)
                return (error);

        error = kernel_sysctl(td, oid, plen / sizeof(int), old, oldlenp,
            new, newlen, retval, flags);
        return (error);
}

/*
 * Transfer function to/from user space.
 */
static int
sysctl_old_user(struct sysctl_req *req, const void *p, size_t l)
{
        size_t i, len, origidx;
        int error;

        origidx = req->oldidx;
        req->oldidx += l;
        if (req->oldptr == NULL)
                return (0);
        /*
         * If we have not wired the user supplied buffer and we are currently
         * holding locks, drop a witness warning, as it's possible that
         * write operations to the user page can sleep.
         */
        if (req->lock != REQ_WIRED)
                WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
                    "sysctl_old_user()");
        i = l;
        len = req->validlen;
        if (len <= origidx)
                i = 0;
        else {
                if (i > len - origidx)
                        i = len - origidx;
                if (req->lock == REQ_WIRED) {
                        error = copyout_nofault(p, (char *)req->oldptr +
                            origidx, i);
                } else
                        error = copyout(p, (char *)req->oldptr + origidx, i);
                if (error != 0)
                        return (error);
        }
        if (i < l)
                return (ENOMEM);
        return (0);
}

static int
sysctl_new_user(struct sysctl_req *req, void *p, size_t l)
{
        int error;

        if (!req->newptr)
                return (0);
        if (req->newlen - req->newidx < l)
                return (EINVAL);
        WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
            "sysctl_new_user()");
        error = copyin((const char *)req->newptr + req->newidx, p, l);
        req->newidx += l;
        return (error);
}

/*
 * Wire the user space destination buffer.  If set to a value greater than
 * zero, the len parameter limits the maximum amount of wired memory.
 */
int
sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
{
        int ret;
        size_t wiredlen;

        wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
        ret = 0;
        if (req->lock != REQ_WIRED && req->oldptr &&
            req->oldfunc == sysctl_old_user) {
                if (wiredlen != 0) {
                        ret = vslock(req->oldptr, wiredlen);
                        if (ret != 0) {
                                if (ret != ENOMEM)
                                        return (ret);
                                wiredlen = 0;
                        }
                }
                req->lock = REQ_WIRED;
                req->validlen = wiredlen;
        }
        return (0);
}

int
sysctl_find_oid(int *name, u_int namelen, struct sysctl_oid **noid,
    int *nindx, struct sysctl_req *req)
{
        struct sysctl_oid_list *lsp;
        struct sysctl_oid *oid;
        struct sysctl_oid key;
        int indx;

        SYSCTL_ASSERT_LOCKED();
        lsp = &sysctl__children;
        indx = 0;
        while (indx < CTL_MAXNAME) {
                key.oid_number = name[indx];
                oid = RB_FIND(sysctl_oid_list, lsp, &key);
                if (oid == NULL)
                        return (ENOENT);

                indx++;
                if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        if (oid->oid_handler != NULL || indx == namelen) {
                                *noid = oid;
                                if (nindx != NULL)
                                        *nindx = indx;
                                KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
                                    ("%s found DYING node %p", __func__, oid));
                                return (0);
                        }
                        lsp = SYSCTL_CHILDREN(oid);
                } else if (indx == namelen) {
                        if ((oid->oid_kind & CTLFLAG_DORMANT) != 0)
                                return (ENOENT);
                        *noid = oid;
                        if (nindx != NULL)
                                *nindx = indx;
                        KASSERT((oid->oid_kind & CTLFLAG_DYING) == 0,
                            ("%s found DYING node %p", __func__, oid));
                        return (0);
                } else {
                        return (ENOTDIR);
                }
        }
        return (ENOENT);
}

/*
 * Traverse our tree, and find the right node, execute whatever it points
 * to, and return the resulting error code.
 */

static int
sysctl_root(SYSCTL_HANDLER_ARGS)
{
        struct sysctl_oid *oid;
        struct rm_priotracker tracker;
        int error, indx, lvl;

        SYSCTL_RLOCK(&tracker);

        error = sysctl_find_oid(arg1, arg2, &oid, &indx, req);
        if (error)
                goto out;

        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                /*
                 * You can't call a sysctl when it's a node, but has
                 * no handler.  Inform the user that it's a node.
                 * The indx may or may not be the same as namelen.
                 */
                if (oid->oid_handler == NULL) {
                        error = EISDIR;
                        goto out;
                }
        }

        /* Is this sysctl writable? */
        if (req->newptr && !(oid->oid_kind & CTLFLAG_WR)) {
                error = EPERM;
                goto out;
        }

        KASSERT(req->td != NULL, ("sysctl_root(): req->td == NULL"));

#ifdef CAPABILITY_MODE
        /*
         * If the process is in capability mode, then don't permit reading or
         * writing unless specifically granted for the node.
         */
        if (IN_CAPABILITY_MODE(req->td)) {
                if ((req->oldptr && !(oid->oid_kind & CTLFLAG_CAPRD)) ||
                    (req->newptr && !(oid->oid_kind & CTLFLAG_CAPWR))) {
                        error = EPERM;
                        goto out;
                }
        }
#endif

        /* Is this sysctl sensitive to securelevels? */
        if (req->newptr && (oid->oid_kind & CTLFLAG_SECURE)) {
                lvl = (oid->oid_kind & CTLMASK_SECURE) >> CTLSHIFT_SECURE;
                error = securelevel_gt(req->td->td_ucred, lvl);
                if (error)
                        goto out;
        }

        /* Is this sysctl writable by only privileged users? */
        if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
                int priv;

                if (oid->oid_kind & CTLFLAG_PRISON)
                        priv = PRIV_SYSCTL_WRITEJAIL;
#ifdef VIMAGE
                else if ((oid->oid_kind & CTLFLAG_VNET) &&
                     prison_owns_vnet(req->td->td_ucred->cr_prison))
                        priv = PRIV_SYSCTL_WRITEJAIL;
#endif
                else
                        priv = PRIV_SYSCTL_WRITE;
                error = priv_check(req->td, priv);
                if (error)
                        goto out;
        }

        if (!oid->oid_handler) {
                error = EINVAL;
                goto out;
        }

        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                arg1 = (int *)arg1 + indx;
                arg2 -= indx;
        } else {
                arg1 = oid->oid_arg1;
                arg2 = oid->oid_arg2;
        }
#ifdef MAC
        error = mac_system_check_sysctl(req->td->td_ucred, oid, arg1, arg2,
            req);
        if (error != 0)
                goto out;
#endif
#ifdef VIMAGE
        if ((oid->oid_kind & CTLFLAG_VNET) && arg1 != NULL)
                arg1 = (void *)(curvnet->vnet_data_base + (uintptr_t)arg1);
#endif
        error = sysctl_root_handler_locked(oid, arg1, arg2, req, &tracker);

out:
        SYSCTL_RUNLOCK(&tracker);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct __sysctl_args {
        int     *name;
        u_int   namelen;
        void    *old;
        size_t  *oldlenp;
        void    *new;
        size_t  newlen;
};
#endif
int
sys___sysctl(struct thread *td, struct __sysctl_args *uap)
{
        int error, i, name[CTL_MAXNAME];
        size_t j;

        if (uap->namelen > CTL_MAXNAME || uap->namelen < 2)
                return (EINVAL);

        error = copyin(uap->name, &name, uap->namelen * sizeof(int));
        if (error)
                return (error);

        error = userland_sysctl(td, name, uap->namelen,
                uap->old, uap->oldlenp, 0,
                uap->new, uap->newlen, &j, 0);
        if (error && error != ENOMEM)
                return (error);
        if (uap->oldlenp) {
                i = copyout(&j, uap->oldlenp, sizeof(j));
                if (i)
                        return (i);
        }
        return (error);
}

int
kern___sysctlbyname(struct thread *td, const char *oname, size_t namelen,
    void *old, size_t *oldlenp, void *new, size_t newlen, size_t *retval,
    int flags, bool inkernel)
{
        int oid[CTL_MAXNAME];
        char namebuf[16];
        char *name;
        size_t oidlen;
        int error;

        if (namelen > MAXPATHLEN || namelen == 0)
                return (EINVAL);
        name = namebuf;
        if (namelen > sizeof(namebuf))
                name = malloc(namelen, M_SYSCTL, M_WAITOK);
        error = copyin(oname, name, namelen);
        if (error != 0)
                goto out;

        oid[0] = CTL_SYSCTL;
        oid[1] = CTL_SYSCTL_NAME2OID;
        oidlen = sizeof(oid);
        error = kernel_sysctl(td, oid, 2, oid, &oidlen, (void *)name, namelen,
            retval, flags);
        if (error != 0)
                goto out;
        error = userland_sysctl(td, oid, *retval / sizeof(int), old, oldlenp,
            inkernel, new, newlen, retval, flags);

out:
        if (namelen > sizeof(namebuf))
                free(name, M_SYSCTL);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct __sysctlbyname_args {
        const char      *name;
        size_t  namelen;
        void    *old;
        size_t  *oldlenp;
        void    *new;
        size_t  newlen;
};
#endif
int
sys___sysctlbyname(struct thread *td, struct __sysctlbyname_args *uap)
{
        size_t rv;
        int error;

        error = kern___sysctlbyname(td, uap->name, uap->namelen, uap->old,
            uap->oldlenp, uap->new, uap->newlen, &rv, 0, 0);
        if (error != 0)
                return (error);
        if (uap->oldlenp != NULL)
                error = copyout(&rv, uap->oldlenp, sizeof(rv));

        return (error);
}

/*
 * This is used from various compatibility syscalls too.  That's why name
 * must be in kernel space.
 */
int
userland_sysctl(struct thread *td, int *name, u_int namelen, void *old,
    size_t *oldlenp, int inkernel, const void *new, size_t newlen,
    size_t *retval, int flags)
{
        struct sysctl_req req;
        int error = 0;
        bool memlocked;

        bzero(&req, sizeof req);

        req.td = td;
        req.flags = flags;

        if (oldlenp) {
                if (inkernel) {
                        req.oldlen = *oldlenp;
                } else {
                        error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
                        if (error)
                                return (error);
                }
        }
        req.validlen = req.oldlen;
        req.oldptr = old;

        if (new != NULL) {
                req.newlen = newlen;
                req.newptr = new;
        }

        req.oldfunc = sysctl_old_user;
        req.newfunc = sysctl_new_user;
        req.lock = REQ_UNWIRED;

#ifdef KTRACE
        if (KTRPOINT(curthread, KTR_SYSCTL))
                ktrsysctl(name, namelen);
#endif
        memlocked = false;
        if (req.oldptr != NULL && req.oldlen > 4 * PAGE_SIZE &&
            priv_check(td, PRIV_SYSCTL_MEMLOCK) != 0) {
                memlocked = true;
                sx_xlock(&sysctlmemlock);
        }
        CURVNET_SET(TD_TO_VNET(td));

        for (;;) {
                req.oldidx = 0;
                req.newidx = 0;
                error = sysctl_root(0, name, namelen, &req);
                if (error != EAGAIN)
                        break;
                kern_yield(PRI_USER);
        }

        CURVNET_RESTORE();

        if (req.lock == REQ_WIRED && req.validlen > 0)
                vsunlock(req.oldptr, req.validlen);
        if (memlocked)
                sx_xunlock(&sysctlmemlock);

        if (error && error != ENOMEM)
                return (error);

        if (retval) {
                if (req.oldptr && req.oldidx > req.validlen)
                        *retval = req.validlen;
                else
                        *retval = req.oldidx;
        }
        return (error);
}

/*
 * Drain into a sysctl struct.  The user buffer should be wired if a page
 * fault would cause issue.
 */
static int
sbuf_sysctl_drain(void *arg, const char *data, int len)
{
        struct sysctl_req *req = arg;
        int error;

        error = SYSCTL_OUT(req, data, len);
        KASSERT(error >= 0, ("Got unexpected negative value %d", error));
        return (error == 0 ? len : -error);
}

struct sbuf *
sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length,
    struct sysctl_req *req)
{

        /* Supply a default buffer size if none given. */
        if (buf == NULL && length == 0)
                length = 64;
        s = sbuf_new(s, buf, length, SBUF_FIXEDLEN | SBUF_INCLUDENUL);
        sbuf_set_drain(s, sbuf_sysctl_drain, req);
        return (s);
}

#ifdef DDB

/* The current OID the debugger is working with */
static struct sysctl_oid *g_ddb_oid;

/* The current flags specified by the user */
static int g_ddb_sysctl_flags;

/* Check to see if the last sysctl printed */
static int g_ddb_sysctl_printed;

static const int ctl_sign[CTLTYPE+1] = {
        [CTLTYPE_INT] = 1,
        [CTLTYPE_LONG] = 1,
        [CTLTYPE_S8] = 1,
        [CTLTYPE_S16] = 1,
        [CTLTYPE_S32] = 1,
        [CTLTYPE_S64] = 1,
};

static const int ctl_size[CTLTYPE+1] = {
        [CTLTYPE_INT] = sizeof(int),
        [CTLTYPE_UINT] = sizeof(u_int),
        [CTLTYPE_LONG] = sizeof(long),
        [CTLTYPE_ULONG] = sizeof(u_long),
        [CTLTYPE_S8] = sizeof(int8_t),
        [CTLTYPE_S16] = sizeof(int16_t),
        [CTLTYPE_S32] = sizeof(int32_t),
        [CTLTYPE_S64] = sizeof(int64_t),
        [CTLTYPE_U8] = sizeof(uint8_t),
        [CTLTYPE_U16] = sizeof(uint16_t),
        [CTLTYPE_U32] = sizeof(uint32_t),
        [CTLTYPE_U64] = sizeof(uint64_t),
};

#define DB_SYSCTL_NAME_ONLY     0x001   /* Compare with -N */
#define DB_SYSCTL_VALUE_ONLY    0x002   /* Compare with -n */
#define DB_SYSCTL_OPAQUE        0x004   /* Compare with -o */
#define DB_SYSCTL_HEX           0x008   /* Compare with -x */

#define DB_SYSCTL_SAFE_ONLY     0x100   /* Only simple types */

static const char db_sysctl_modifs[] = {
        'N', 'n', 'o', 'x',
};

static const int db_sysctl_modif_values[] = {
        DB_SYSCTL_NAME_ONLY, DB_SYSCTL_VALUE_ONLY,
        DB_SYSCTL_OPAQUE, DB_SYSCTL_HEX,
};

/* Handlers considered safe to print while recursing */
static int (* const db_safe_handlers[])(SYSCTL_HANDLER_ARGS) = {
        sysctl_handle_bool,
        sysctl_handle_8,
        sysctl_handle_16,
        sysctl_handle_32,
        sysctl_handle_64,
        sysctl_handle_int,
        sysctl_handle_long,
        sysctl_handle_string,
        sysctl_handle_opaque,
};

/*
 * Use in place of sysctl_old_kernel to print sysctl values.
 *
 * Compare to the output handling in show_var from sbin/sysctl/sysctl.c
 */
static int
sysctl_old_ddb(struct sysctl_req *req, const void *ptr, size_t len)
{
        const u_char *val, *p;
        const char *sep1;
        size_t intlen, slen;
        uintmax_t umv;
        intmax_t mv;
        int sign, ctltype, hexlen, xflag, error;

        /* Suppress false-positive GCC uninitialized variable warnings */
        mv = 0;
        umv = 0;

        slen = len;
        val = p = ptr;

        if (ptr == NULL) {
                error = 0;
                goto out;
        }

        /* We are going to print */
        g_ddb_sysctl_printed = 1;

        xflag = g_ddb_sysctl_flags & DB_SYSCTL_HEX;

        ctltype = (g_ddb_oid->oid_kind & CTLTYPE);
        sign = ctl_sign[ctltype];
        intlen = ctl_size[ctltype];

        switch (ctltype) {
        case CTLTYPE_NODE:
        case CTLTYPE_STRING:
                db_printf("%.*s", (int) len, (const char *) p);
                error = 0;
                goto out;

        case CTLTYPE_INT:
        case CTLTYPE_UINT:
        case CTLTYPE_LONG:
        case CTLTYPE_ULONG:
        case CTLTYPE_S8:
        case CTLTYPE_S16:
        case CTLTYPE_S32:
        case CTLTYPE_S64:
        case CTLTYPE_U8:
        case CTLTYPE_U16:
        case CTLTYPE_U32:
        case CTLTYPE_U64:
                hexlen = 2 + (intlen * CHAR_BIT + 3) / 4;
                sep1 = "";
                while (len >= intlen) {
                        switch (ctltype) {
                        case CTLTYPE_INT:
                        case CTLTYPE_UINT:
                                umv = *(const u_int *)p;
                                mv = *(const int *)p;
                                break;
                        case CTLTYPE_LONG:
                        case CTLTYPE_ULONG:
                                umv = *(const u_long *)p;
                                mv = *(const long *)p;
                                break;
                        case CTLTYPE_S8:
                        case CTLTYPE_U8:
                                umv = *(const uint8_t *)p;
                                mv = *(const int8_t *)p;
                                break;
                        case CTLTYPE_S16:
                        case CTLTYPE_U16:
                                umv = *(const uint16_t *)p;
                                mv = *(const int16_t *)p;
                                break;
                        case CTLTYPE_S32:
                        case CTLTYPE_U32:
                                umv = *(const uint32_t *)p;
                                mv = *(const int32_t *)p;
                                break;
                        case CTLTYPE_S64:
                        case CTLTYPE_U64:
                                umv = *(const uint64_t *)p;
                                mv = *(const int64_t *)p;
                                break;
                        }

                        db_printf("%s", sep1);
                        if (xflag)
                                db_printf("%#0*jx", hexlen, umv);
                        else if (!sign)
                                db_printf("%ju", umv);
                        else if (g_ddb_oid->oid_fmt[1] == 'K') {
                                /* Kelvins are currently unsupported. */
                                error = EOPNOTSUPP;
                                goto out;
                        } else
                                db_printf("%jd", mv);

                        sep1 = " ";
                        len -= intlen;
                        p += intlen;
                }
                error = 0;
                goto out;

        case CTLTYPE_OPAQUE:
                /* TODO: Support struct functions. */

                /* FALLTHROUGH */
        default:
                db_printf("Format:%s Length:%zu Dump:0x",
                    g_ddb_oid->oid_fmt, len);
                while (len-- && (xflag || p < val + 16))
                        db_printf("%02x", *p++);
                if (!xflag && len > 16)
                        db_printf("...");
                error = 0;
                goto out;
        }

out:
        req->oldidx += slen;
        return (error);
}

/*
 * Avoid setting new sysctl values from the debugger
 */
static int
sysctl_new_ddb(struct sysctl_req *req, void *p, size_t l)
{

        if (!req->newptr)
                return (0);

        /* Changing sysctls from the debugger is currently unsupported */
        return (EPERM);
}

/*
 * Run a sysctl handler with the DDB oldfunc and newfunc attached.
 * Instead of copying any output to a buffer we'll dump it right to
 * the console.
 */
static int
db_sysctl(struct sysctl_oid *oidp, int *name, u_int namelen,
    void *old, size_t *oldlenp, size_t *retval, int flags)
{
        struct sysctl_req req;
        int error;

        /* Setup the request */
        bzero(&req, sizeof req);
        req.td = kdb_thread;
        req.oldfunc = sysctl_old_ddb;
        req.newfunc = sysctl_new_ddb;
        req.lock = REQ_UNWIRED;
        if (oldlenp) {
                req.oldlen = *oldlenp;
        }
        req.validlen = req.oldlen;
        if (old) {
                req.oldptr = old;
        }

        /* Setup our globals for sysctl_old_ddb */
        g_ddb_oid = oidp;
        g_ddb_sysctl_flags = flags;
        g_ddb_sysctl_printed = 0;

        error = sysctl_root(0, name, namelen, &req);

        /* Reset globals */
        g_ddb_oid = NULL;
        g_ddb_sysctl_flags = 0;

        if (retval) {
                if (req.oldptr && req.oldidx > req.validlen)
                        *retval = req.validlen;
                else
                        *retval = req.oldidx;
        }
        return (error);
}

/*
 * Show a sysctl's name
 */
static void
db_show_oid_name(int *oid, size_t nlen)
{
        struct sysctl_oid *oidp;
        int qoid[CTL_MAXNAME + 2];
        int error;

        qoid[0] = CTL_SYSCTL;
        qoid[1] = CTL_SYSCTL_NAME;
        memcpy(qoid + 2, oid, nlen * sizeof(int));

        error = sysctl_find_oid(qoid, nlen + 2, &oidp, NULL, NULL);
        if (error)
                db_error("sysctl name oid");

        error = db_sysctl(oidp, qoid, nlen + 2, NULL, NULL, NULL, 0);
        if (error)
                db_error("sysctl name");
}

/*
 * Check to see if an OID is safe to print from ddb.
 */
static bool
db_oid_safe(const struct sysctl_oid *oidp)
{
        for (unsigned int i = 0; i < nitems(db_safe_handlers); ++i) {
                if (oidp->oid_handler == db_safe_handlers[i])
                        return (true);
        }

        return (false);
}

/*
 * Show a sysctl at a specific OID
 * Compare to the input handling in show_var from sbin/sysctl/sysctl.c
 */
static int
db_show_oid(struct sysctl_oid *oidp, int *oid, size_t nlen, int flags)
{
        int error, xflag, oflag, Nflag, nflag;
        size_t len;

        xflag = flags & DB_SYSCTL_HEX;
        oflag = flags & DB_SYSCTL_OPAQUE;
        nflag = flags & DB_SYSCTL_VALUE_ONLY;
        Nflag = flags & DB_SYSCTL_NAME_ONLY;

        if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_OPAQUE &&
            (!xflag && !oflag))
                return (0);

        if (Nflag) {
                db_show_oid_name(oid, nlen);
                error = 0;
                goto out;
        }

        if (!nflag) {
                db_show_oid_name(oid, nlen);
                db_printf(": ");
        }

        if ((flags & DB_SYSCTL_SAFE_ONLY) && !db_oid_safe(oidp)) {
                db_printf("Skipping, unsafe to print while recursing.");
                error = 0;
                goto out;
        }

        /* Try once, and ask about the size */
        len = 0;
        error = db_sysctl(oidp, oid, nlen,
            NULL, NULL, &len, flags);
        if (error)
                goto out;

        if (!g_ddb_sysctl_printed)
                /* Lie about the size */
                error = db_sysctl(oidp, oid, nlen,
                    (void *) 1, &len, NULL, flags);

out:
        db_printf("\n");
        return (error);
}

/*
 * Show all sysctls under a specific OID
 * Compare to sysctl_all from sbin/sysctl/sysctl.c
 */
static int
db_show_sysctl_all(int *oid, size_t len, int flags)
{
        struct sysctl_oid *oidp;
        int qoid[CTL_MAXNAME + 2], next[CTL_MAXNAME];
        size_t nlen;

        qoid[0] = CTL_SYSCTL;
        qoid[1] = CTL_SYSCTL_NEXT;
        if (len) {
                nlen = len;
                memcpy(&qoid[2], oid, nlen * sizeof(int));
        } else {
                nlen = 1;
                qoid[2] = CTL_KERN;
        }
        for (;;) {
                int error;
                size_t nextsize = sizeof(next);

                error = kernel_sysctl(kdb_thread, qoid, nlen + 2,
                    next, &nextsize, NULL, 0, &nlen, 0);
                if (error != 0) {
                        if (error == ENOENT)
                                return (0);
                        else
                                db_error("sysctl(next)");
                }

                nlen /= sizeof(int);

                if (nlen < (unsigned int)len)
                        return (0);

                if (memcmp(&oid[0], &next[0], len * sizeof(int)) != 0)
                        return (0);

                /* Find the OID in question */
                error = sysctl_find_oid(next, nlen, &oidp, NULL, NULL);
                if (error)
                        return (error);

                (void)db_show_oid(oidp, next, nlen, flags | DB_SYSCTL_SAFE_ONLY);

                if (db_pager_quit)
                        return (0);

                memcpy(&qoid[2 + len], &next[len], (nlen - len) * sizeof(int));
        }
}

/*
 * Show a sysctl by its user facing string
 */
static int
db_sysctlbyname(const char *name, int flags)
{
        struct sysctl_oid *oidp;
        int oid[CTL_MAXNAME];
        int error, nlen;

        error = name2oid(name, oid, &nlen, &oidp);
        if (error) {
                return (error);
        }

        if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                db_show_sysctl_all(oid, nlen, flags);
        } else {
                error = db_show_oid(oidp, oid, nlen, flags);
        }

        return (error);
}

static void
db_sysctl_cmd_usage(void)
{
        db_printf(
            " sysctl [/Nnox] <sysctl>                                       \n"
            "                                                               \n"
            " <sysctl> The name of the sysctl to show.                      \n"
            "                                                               \n"
            " Show a sysctl by hooking into SYSCTL_IN and SYSCTL_OUT.       \n"
            " This will work for most sysctls, but should not be used       \n"
            " with sysctls that are known to malloc.                        \n"
            "                                                               \n"
            " While recursing any \"unsafe\" sysctls will be skipped.       \n"
            " Call sysctl directly on the sysctl to try printing the        \n"
            " skipped sysctl. This is unsafe and may make the ddb           \n"
            " session unusable.                                             \n"
            "                                                               \n"
            " Arguments:                                                    \n"
            "   /N      Display only the name of the sysctl.                \n"
            "   /n      Display only the value of the sysctl.               \n"
            "   /o      Display opaque values.                              \n"
            "   /x      Display the sysctl in hex.                          \n"
            "                                                               \n"
            "For example:                                                   \n"
            "sysctl vm.v_free_min                                           \n"
            "vn.v_free_min: 12669                                           \n"
            );
}

/*
 * Show a specific sysctl similar to sysctl (8).
 */
DB_COMMAND_FLAGS(sysctl, db_sysctl_cmd, CS_OWN)
{
        char name[TOK_STRING_SIZE];
        int error, i, t, flags;

        /* Parse the modifiers */
        t = db_read_token();
        if (t == tSLASH || t == tMINUS) {
                t = db_read_token();
                if (t != tIDENT) {
                        db_printf("Bad modifier\n");
                        error = EINVAL;
                        goto out;
                }
                db_strcpy(modif, db_tok_string);
        }
        else {
                db_unread_token(t);
                modif[0] = '\0';
        }

        flags = 0;
        for (i = 0; i < nitems(db_sysctl_modifs); i++) {
                if (strchr(modif, db_sysctl_modifs[i])) {
                        flags |= db_sysctl_modif_values[i];
                }
        }

        /* Parse the sysctl names */
        t = db_read_token();
        if (t != tIDENT) {
                db_printf("Need sysctl name\n");
                error = EINVAL;
                goto out;
        }

        /* Copy the name into a temporary buffer */
        db_strcpy(name, db_tok_string);

        /* Ensure there is no trailing cruft */
        t = db_read_token();
        if (t != tEOL) {
                db_printf("Unexpected sysctl argument\n");
                error = EINVAL;
                goto out;
        }

        error = db_sysctlbyname(name, flags);
        if (error == ENOENT) {
                db_printf("unknown oid: '%s'\n", db_tok_string);
                goto out;
        } else if (error) {
                db_printf("%s: error: %d\n", db_tok_string, error);
                goto out;
        }

out:
        /* Ensure we eat all of our text */
        db_flush_lex();

        if (error == EINVAL) {
                db_sysctl_cmd_usage();
        }
}

#endif /* DDB */