Ignore machine-check MSRs

[freebsd-src/fkvm-freebsd.git] / sys / kern / kern_sysctl.c

/*-
 * 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.
 * 4. 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.
 *
 *      @(#)kern_sysctl.c       8.4 (Berkeley) 4/14/94
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_compat.h"
#include "opt_mac.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/sysproto.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");

/*
 * Locking - this locks the sysctl tree in memory.
 */
static struct sx sysctllock;

#define SYSCTL_LOCK()           sx_xlock(&sysctllock)
#define SYSCTL_UNLOCK()         sx_xunlock(&sysctllock)
#define SYSCTL_INIT()           sx_init(&sysctllock, "sysctl lock")

static int sysctl_root(SYSCTL_HANDLER_ARGS);

struct sysctl_oid_list sysctl__children; /* root list */

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

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

/*
 * Initialization of the MIB tree.
 *
 * Order by number in each list.
 */

void
sysctl_register_oid(struct sysctl_oid *oidp)
{
        struct sysctl_oid_list *parent = oidp->oid_parent;
        struct sysctl_oid *p;
        struct sysctl_oid *q;

        /*
         * First check if another oid with the same name already
         * exists in the parent's list.
         */
        p = sysctl_find_oidname(oidp->oid_name, parent);
        if (p != NULL) {
                if ((p->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        p->oid_refcnt++;
                        return;
                } else {
                        printf("can't re-use a leaf (%s)!\n", p->oid_name);
                        return;
                }
        }
        /*
         * If this oid has a number OID_AUTO, give it a number which
         * is greater than any current oid.
         * NOTE: DO NOT change the starting value here, change it in
         * <sys/sysctl.h>, and make sure it is at least 256 to
         * accomodate e.g. net.inet.raw as a static sysctl node.
         */
        if (oidp->oid_number == OID_AUTO) {
                static int newoid = CTL_AUTO_START;

                oidp->oid_number = newoid++;
                if (newoid == 0x7fffffff)
                        panic("out of oids");
        }
#if 0
        else if (oidp->oid_number >= CTL_AUTO_START) {
                /* do not panic; this happens when unregistering sysctl sets */
                printf("static sysctl oid too high: %d", oidp->oid_number);
        }
#endif

        /*
         * Insert the oid into the parent's list in order.
         */
        q = NULL;
        SLIST_FOREACH(p, parent, oid_link) {
                if (oidp->oid_number < p->oid_number)
                        break;
                q = p;
        }
        if (q)
                SLIST_INSERT_AFTER(q, oidp, oid_link);
        else
                SLIST_INSERT_HEAD(parent, oidp, oid_link);
}

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

        error = ENOENT;
        if (oidp->oid_number == OID_AUTO) {
                error = EINVAL;
        } else {
                SLIST_FOREACH(p, oidp->oid_parent, oid_link) {
                        if (p == oidp) {
                                SLIST_REMOVE(oidp->oid_parent, oidp,
                                    sysctl_oid, oid_link);
                                error = 0;
                                break;
                        }
                }
        }

        /* 
         * 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 to unregister sysctl\n", __func__);
}

/* 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);
        }
        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...
         */
        TAILQ_FOREACH(e, clist, link) {
                error = sysctl_remove_oid(e->entry, 0, 0);
                if (error)
                        break;
        }
        /*
         * Restore deregistered entries, either from the end,
         * or from the place where error occured.
         * 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)
                return(EBUSY);
        /* Now really delete the entries */
        e = TAILQ_FIRST(clist);
        while (e != NULL) {
                e1 = TAILQ_NEXT(e, link);
                error = sysctl_remove_oid(e->entry, 1, 0);
                if (error)
                        panic("sysctl_remove_oid: corrupt tree, entry: %s",
                            e->entry->oid_name);
                free(e, M_SYSCTLOID);
                e = e1;
        }
        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;

        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;

        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);
        e = sysctl_ctx_entry_find(clist, oidp);
        if (e != NULL) {
                TAILQ_REMOVE(clist, e, link);
                free(e, M_SYSCTLOID);
                return (0);
        } else
                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)
{
        struct sysctl_oid *p;
        int error;

        if (oidp == NULL)
                return(EINVAL);
        if ((oidp->oid_kind & CTLFLAG_DYN) == 0) {
                printf("can't remove non-dynamic nodes!\n");
                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) {
                        SLIST_FOREACH(p, SYSCTL_CHILDREN(oidp), oid_link) {
                                if (!recurse)
                                        return (ENOTEMPTY);
                                error = sysctl_remove_oid(p, del, recurse);
                                if (error)
                                        return (error);
                        }
                        if (del)
                                free(SYSCTL_CHILDREN(oidp), M_SYSCTLOID);
                }
        }
        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) {
                        if (oidp->oid_descr)
                                free((void *)(uintptr_t)(const void *)oidp->oid_descr, M_SYSCTLOID);
                        free((void *)(uintptr_t)(const void *)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, int arg2,
        int (*handler)(SYSCTL_HANDLER_ARGS), const char *fmt, const char *descr)
{
        struct sysctl_oid *oidp;
        ssize_t len;
        char *newname;

        /* You have to hook up somewhere.. */
        if (parent == NULL)
                return(NULL);
        /* Check if the node already exists, otherwise create it */
        oidp = sysctl_find_oidname(name, parent);
        if (oidp != NULL) {
                if ((oidp->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                        oidp->oid_refcnt++;
                        /* Update the context */
                        if (clist != NULL)
                                sysctl_ctx_entry_add(clist, oidp);
                        return (oidp);
                } else {
                        printf("can't re-use a leaf (%s)!\n", name);
                        return (NULL);
                }
        }
        oidp = malloc(sizeof(struct sysctl_oid), M_SYSCTLOID, M_WAITOK|M_ZERO);
        oidp->oid_parent = parent;
        SLIST_NEXT(oidp, oid_link) = NULL;
        oidp->oid_number = number;
        oidp->oid_refcnt = 1;
        len = strlen(name);
        newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
        bcopy(name, newname, len + 1);
        newname[len] = '\0';
        oidp->oid_name = newname;
        oidp->oid_handler = handler;
        oidp->oid_kind = CTLFLAG_DYN | kind;
        if ((kind & CTLTYPE) == CTLTYPE_NODE) {
                /* Allocate space for children */
                SYSCTL_CHILDREN_SET(oidp, malloc(sizeof(struct sysctl_oid_list),
                    M_SYSCTLOID, M_WAITOK));
                SLIST_INIT(SYSCTL_CHILDREN(oidp));
        } else {
                oidp->oid_arg1 = arg1;
                oidp->oid_arg2 = arg2;
        }
        oidp->oid_fmt = fmt;
        if (descr) {
                int len = strlen(descr) + 1;
                oidp->oid_descr = malloc(len, M_SYSCTLOID, M_WAITOK);
                if (oidp->oid_descr)
                        strcpy((char *)(uintptr_t)(const void *)oidp->oid_descr, descr);
        }
        /* Update the context, if used */
        if (clist != NULL)
                sysctl_ctx_entry_add(clist, oidp);
        /* Register this oid */
        sysctl_register_oid(oidp);
        return (oidp);
}

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

        oldname = (void *)(uintptr_t)(const void *)oidp->oid_name;
        len = strlen(name);
        newname = malloc(len + 1, M_SYSCTLOID, M_WAITOK);
        bcopy(name, newname, len + 1);
        newname[len] = '\0';
        oidp->oid_name = newname;
        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;

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

        SYSCTL_INIT();
        SET_FOREACH(oidp, sysctl_set)
                sysctl_register_oid(*oidp);
}
SYSINIT(sysctl, SI_SUB_KMEM, SI_ORDER_ANY, sysctl_register_all, 0);

/*
 * "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.
 *
 * {0,0}        printf the entire MIB-tree.
 * {0,1,...}    return the name of the "..." OID.
 * {0,2,...}    return the next OID.
 * {0,3}        return the OID of the name in "new"
 * {0,4,...}    return the kind & format info for the "..." OID.
 * {0,5,...}    return the description the "..." OID.
 */

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

        SLIST_FOREACH(oidp, l, oid_link) {

                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(
                                                oidp->oid_arg1, i+2);
                                }
                                break;
                        case CTLTYPE_INT:    printf(" Int\n"); break;
                        case CTLTYPE_STRING: printf(" String\n"); break;
                        case CTLTYPE_QUAD:   printf(" Quad\n"); break;
                        case CTLTYPE_OPAQUE: printf(" Opaque/struct\n"); break;
                        default:             printf("\n");
                }

        }
}

static int
sysctl_sysctl_debug(SYSCTL_HANDLER_ARGS)
{
        int error;

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

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

static int
sysctl_sysctl_name(SYSCTL_HANDLER_ARGS)
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int error = 0;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children, *lsp2;
        char buf[10];

        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)
                                return (error);
                        namelen--;
                        name++;
                        continue;
                }
                lsp2 = 0;
                SLIST_FOREACH(oid, lsp, oid_link) {
                        if (oid->oid_number != *name)
                                continue;

                        if (req->oldidx)
                                error = SYSCTL_OUT(req, ".", 1);
                        if (!error)
                                error = SYSCTL_OUT(req, oid->oid_name,
                                        strlen(oid->oid_name));
                        if (error)
                                return (error);

                        namelen--;
                        name++;

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

                        if (oid->oid_handler)
                                break;

                        lsp2 = (struct sysctl_oid_list *)oid->oid_arg1;
                        break;
                }
                lsp = lsp2;
        }
        return (SYSCTL_OUT(req, "", 1));
}

static SYSCTL_NODE(_sysctl, 1, name, CTLFLAG_RD, sysctl_sysctl_name, "");

static int
sysctl_sysctl_next_ls(struct sysctl_oid_list *lsp, int *name, u_int namelen, 
        int *next, int *len, int level, struct sysctl_oid **oidpp)
{
        struct sysctl_oid *oidp;

        *len = level;
        SLIST_FOREACH(oidp, lsp, oid_link) {
                *next = oidp->oid_number;
                *oidpp = oidp;

                if (oidp->oid_kind & CTLFLAG_SKIP)
                        continue;

                if (!namelen) {
                        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE) 
                                return (0);
                        if (oidp->oid_handler) 
                                /* We really should call the handler here...*/
                                return (0);
                        lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                        if (!sysctl_sysctl_next_ls(lsp, 0, 0, next+1, 
                                len, level+1, oidpp))
                                return (0);
                        goto emptynode;
                }

                if (oidp->oid_number < *name)
                        continue;

                if (oidp->oid_number > *name) {
                        if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                                return (0);
                        if (oidp->oid_handler)
                                return (0);
                        lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                        if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, 
                                next+1, len, level+1, oidpp))
                                return (0);
                        goto next;
                }
                if ((oidp->oid_kind & CTLTYPE) != CTLTYPE_NODE)
                        continue;

                if (oidp->oid_handler)
                        continue;

                lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                if (!sysctl_sysctl_next_ls(lsp, name+1, namelen-1, next+1, 
                        len, level+1, oidpp))
                        return (0);
        next:
                namelen = 1;
        emptynode:
                *len = level;
        }
        return (1);
}

static int
sysctl_sysctl_next(SYSCTL_HANDLER_ARGS)
{
        int *name = (int *) arg1;
        u_int namelen = arg2;
        int i, j, error;
        struct sysctl_oid *oid;
        struct sysctl_oid_list *lsp = &sysctl__children;
        int newoid[CTL_MAXNAME];

        i = sysctl_sysctl_next_ls(lsp, name, namelen, newoid, &j, 1, &oid);
        if (i)
                return (ENOENT);
        error = SYSCTL_OUT(req, newoid, j * sizeof (int));
        return (error);
}

static SYSCTL_NODE(_sysctl, 2, next, CTLFLAG_RD, sysctl_sysctl_next, "");

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

        if (!*name)
                return (ENOENT);

        p = name + strlen(name) - 1 ;
        if (*p == '.')
                *p = '\0';

        *len = 0;

        for (p = name; *p && *p != '.'; p++) 
                ;
        i = *p;
        if (i == '.')
                *p = '\0';

        oidp = SLIST_FIRST(lsp);

        while (oidp && *len < CTL_MAXNAME) {
                if (strcmp(name, oidp->oid_name)) {
                        oidp = SLIST_NEXT(oidp, oid_link);
                        continue;
                }
                *oid++ = oidp->oid_number;
                (*len)++;

                if (!i) {
                        if (oidpp)
                                *oidpp = oidp;
                        return (0);
                }

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

                if (oidp->oid_handler)
                        break;

                lsp = (struct sysctl_oid_list *)oidp->oid_arg1;
                oidp = SLIST_FIRST(lsp);
                name = p+1;
                for (p = name; *p && *p != '.'; p++) 
                                ;
                i = *p;
                if (i == '.')
                        *p = '\0';
        }
        return (ENOENT);
}

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

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

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

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

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

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

        free(p, M_SYSCTL);

        if (error)
                return (error);

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

SYSCTL_PROC(_sysctl, 3, name2oid, CTLFLAG_RW|CTLFLAG_ANYBODY, 0, 0, 
        sysctl_sysctl_name2oid, "I", "");

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

        error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
        if (error)
                return (error);

        if (!oid->oid_fmt)
                return (ENOENT);
        error = SYSCTL_OUT(req, &oid->oid_kind, sizeof(oid->oid_kind));
        if (error)
                return (error);
        error = SYSCTL_OUT(req, oid->oid_fmt, strlen(oid->oid_fmt) + 1);
        return (error);
}


static SYSCTL_NODE(_sysctl, 4, oidfmt, CTLFLAG_RD, sysctl_sysctl_oidfmt, "");

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

        error = sysctl_find_oid(arg1, arg2, &oid, NULL, req);
        if (error)
                return (error);

        if (!oid->oid_descr)
                return (ENOENT);
        error = SYSCTL_OUT(req, oid->oid_descr, strlen(oid->oid_descr) + 1);
        return (error);
}

static SYSCTL_NODE(_sysctl, 5, oiddescr, CTLFLAG_RD, sysctl_sysctl_oiddescr, "");

/*
 * Default "handler" functions.
 */

/*
 * 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 on sysctl_handle_int() convert milliseconds into ticks.
 */

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

        tt = *(int *)oidp->oid_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 *)oidp->oid_arg1 = tt;
        return (0);
}


/*
 * Handle a long, signed or unsigned.  arg1 points to it.
 */

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)
                return (EINVAL);
        tmplong = *(long *)arg1;
#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);

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

/*
 * Handle a 64 bit int, signed or unsigned.  arg1 points to it.
 */

int
sysctl_handle_quad(SYSCTL_HANDLER_ARGS)
{
        int error = 0;
        uint64_t tmpout;

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

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

        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)
{
        int error=0;
        char *tmparg;
        size_t outlen;

        /*
         * Attempt to get a coherent snapshot by copying to a
         * temporary kernel buffer.
         */
retry:
        outlen = strlen((char *)arg1)+1;
        tmparg = malloc(outlen, M_SYSCTLTMP, M_WAITOK);

        if (strlcpy(tmparg, (char *)arg1, outlen) >= outlen) {
                free(tmparg, M_SYSCTLTMP);
                goto retry;
        }

        error = SYSCTL_OUT(req, tmparg, outlen);
        free(tmparg, M_SYSCTLTMP);

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

        if ((req->newlen - req->newidx) >= arg2) {
                error = EINVAL;
        } else {
                arg2 = (req->newlen - req->newidx);
                error = SYSCTL_IN(req, arg1, arg2);
                ((char *)arg1)[arg2] = '\0';
        }

        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);
}

/*
 * 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((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_LOCKED;

        SYSCTL_LOCK();

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

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

        SYSCTL_UNLOCK();

        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] = 0;             /* sysctl internal magic */
        oid[1] = 3;             /* 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)
{
        int error = 0;
        size_t i, len, origidx;

        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;
                error = copyout(p, (char *)req->oldptr + origidx, i);
        }
        if (error)
                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((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 i, wiredlen;
        char *cp, dummy;

        wiredlen = (len > 0 && len < req->oldlen) ? len : req->oldlen;
        ret = 0;
        if (req->lock == REQ_LOCKED && 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;
                        }
                        /*
                         * Touch all the wired pages to avoid PTE modified
                         * bit emulation traps on Alpha while holding locks
                         * in the sysctl handler.
                         */
                        for (i = (wiredlen + PAGE_SIZE - 1) / PAGE_SIZE,
                            cp = req->oldptr; i > 0; i--, cp += PAGE_SIZE) {
                                copyin(cp, &dummy, 1);
                                copyout(&dummy, cp, 1);
                        }
                }
                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 *oid;
        int indx;

        oid = SLIST_FIRST(&sysctl__children);
        indx = 0;
        while (oid && indx < CTL_MAXNAME) {
                if (oid->oid_number == name[indx]) {
                        indx++;
                        if (oid->oid_kind & CTLFLAG_NOLOCK)
                                req->lock = REQ_UNLOCKED;
                        if ((oid->oid_kind & CTLTYPE) == CTLTYPE_NODE) {
                                if (oid->oid_handler != NULL ||
                                    indx == namelen) {
                                        *noid = oid;
                                        if (nindx != NULL)
                                                *nindx = indx;
                                        return (0);
                                }
                                oid = SLIST_FIRST(
                                    (struct sysctl_oid_list *)oid->oid_arg1);
                        } else if (indx == namelen) {
                                *noid = oid;
                                if (nindx != NULL)
                                        *nindx = indx;
                                return (0);
                        } else {
                                return (ENOTDIR);
                        }
                } else {
                        oid = SLIST_NEXT(oid, oid_link);
                }
        }
        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;
        int error, indx, lvl;

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

        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)
                        return (EISDIR);
        }

        /* Is this sysctl writable? */
        if (req->newptr && !(oid->oid_kind & CTLFLAG_WR))
                return (EPERM);

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

        /* 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)
                        return (error);
        }

        /* Is this sysctl writable by only privileged users? */
        if (req->newptr && !(oid->oid_kind & CTLFLAG_ANYBODY)) {
                if (oid->oid_kind & CTLFLAG_PRISON)
                        error = priv_check(req->td, PRIV_SYSCTL_WRITEJAIL);
                else
                        error = priv_check(req->td, PRIV_SYSCTL_WRITE);
                if (error)
                        return (error);
        }

        if (!oid->oid_handler)
                return (EINVAL);

        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)
                return (error);
#endif
        error = oid->oid_handler(oid, arg1, arg2, req);

        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
__sysctl(struct thread *td, struct sysctl_args *uap)
{
        int error, 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);

        mtx_lock(&Giant);

        error = userland_sysctl(td, name, uap->namelen,
                uap->old, uap->oldlenp, 0,
                uap->new, uap->newlen, &j, 0);
        if (error && error != ENOMEM)
                goto done2;
        if (uap->oldlenp) {
                int i = copyout(&j, uap->oldlenp, sizeof(j));
                if (i)
                        error = i;
        }
done2:
        mtx_unlock(&Giant);
        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, 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) {
                if (inkernel) {
                        req.oldlen = *oldlenp;
                } else {
                        error = copyin(oldlenp, &req.oldlen, sizeof(*oldlenp));
                        if (error)
                                return (error);
                }
        }
        req.validlen = req.oldlen;

        if (old) {
                if (!useracc(old, req.oldlen, VM_PROT_WRITE))
                        return (EFAULT);
                req.oldptr= old;
        }

        if (new != NULL) {
                if (!useracc(new, newlen, VM_PROT_READ))
                        return (EFAULT);
                req.newlen = newlen;
                req.newptr = new;
        }

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

        SYSCTL_LOCK();

        do {
                req.oldidx = 0;
                req.newidx = 0;
                error = sysctl_root(0, name, namelen, &req);
        } while (error == EAGAIN);

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

        SYSCTL_UNLOCK();

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

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

#ifdef COMPAT_43
#include <sys/socket.h>
#include <vm/vm_param.h>

#define KINFO_PROC              (0<<8)
#define KINFO_RT                (1<<8)
#define KINFO_VNODE             (2<<8)
#define KINFO_FILE              (3<<8)
#define KINFO_METER             (4<<8)
#define KINFO_LOADAVG           (5<<8)
#define KINFO_CLOCKRATE         (6<<8)

/* Non-standard BSDI extension - only present on their 4.3 net-2 releases */
#define KINFO_BSDI_SYSINFO      (101<<8)

/*
 * XXX this is bloat, but I hope it's better here than on the potentially
 * limited kernel stack...  -Peter
 */

static struct {
        int     bsdi_machine;           /* "i386" on BSD/386 */
/*      ^^^ this is an offset to the string, relative to the struct start */
        char    *pad0;
        long    pad1;
        long    pad2;
        long    pad3;
        u_long  pad4;
        u_long  pad5;
        u_long  pad6;

        int     bsdi_ostype;            /* "BSD/386" on BSD/386 */
        int     bsdi_osrelease;         /* "1.1" on BSD/386 */
        long    pad7;
        long    pad8;
        char    *pad9;

        long    pad10;
        long    pad11;
        int     pad12;
        long    pad13;
        quad_t  pad14;
        long    pad15;

        struct  timeval pad16;
        /* we dont set this, because BSDI's uname used gethostname() instead */
        int     bsdi_hostname;          /* hostname on BSD/386 */

        /* the actual string data is appended here */

} bsdi_si;

/*
 * this data is appended to the end of the bsdi_si structure during copyout.
 * The "char *" offsets are relative to the base of the bsdi_si struct.
 * This contains "FreeBSD\02.0-BUILT-nnnnnn\0i386\0", and these strings
 * should not exceed the length of the buffer here... (or else!! :-)
 */
static char bsdi_strings[80];   /* It had better be less than this! */

#ifndef _SYS_SYSPROTO_H_
struct getkerninfo_args {
        int     op;
        char    *where;
        size_t  *size;
        int     arg;
};
#endif
int
ogetkerninfo(struct thread *td, struct getkerninfo_args *uap)
{
        int error, name[6];
        size_t size;
        u_int needed = 0;

        mtx_lock(&Giant);

        switch (uap->op & 0xff00) {

        case KINFO_RT:
                name[0] = CTL_NET;
                name[1] = PF_ROUTE;
                name[2] = 0;
                name[3] = (uap->op & 0xff0000) >> 16;
                name[4] = uap->op & 0xff;
                name[5] = uap->arg;
                error = userland_sysctl(td, name, 6, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_VNODE:
                name[0] = CTL_KERN;
                name[1] = KERN_VNODE;
                error = userland_sysctl(td, name, 2, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_PROC:
                name[0] = CTL_KERN;
                name[1] = KERN_PROC;
                name[2] = uap->op & 0xff;
                name[3] = uap->arg;
                error = userland_sysctl(td, name, 4, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_FILE:
                name[0] = CTL_KERN;
                name[1] = KERN_FILE;
                error = userland_sysctl(td, name, 2, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_METER:
                name[0] = CTL_VM;
                name[1] = VM_TOTAL;
                error = userland_sysctl(td, name, 2, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_LOADAVG:
                name[0] = CTL_VM;
                name[1] = VM_LOADAVG;
                error = userland_sysctl(td, name, 2, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_CLOCKRATE:
                name[0] = CTL_KERN;
                name[1] = KERN_CLOCKRATE;
                error = userland_sysctl(td, name, 2, uap->where, uap->size,
                        0, 0, 0, &size, 0);
                break;

        case KINFO_BSDI_SYSINFO: {
                /*
                 * this is pretty crude, but it's just enough for uname()
                 * from BSDI's 1.x libc to work.
                 *
                 * *size gives the size of the buffer before the call, and
                 * the amount of data copied after a successful call.
                 * If successful, the return value is the amount of data
                 * available, which can be larger than *size.
                 *
                 * BSDI's 2.x product apparently fails with ENOMEM if *size
                 * is too small.
                 */

                u_int left;
                char *s;

                bzero((char *)&bsdi_si, sizeof(bsdi_si));
                bzero(bsdi_strings, sizeof(bsdi_strings));

                s = bsdi_strings;

                bsdi_si.bsdi_ostype = (s - bsdi_strings) + sizeof(bsdi_si);
                strcpy(s, ostype);
                s += strlen(s) + 1;

                bsdi_si.bsdi_osrelease = (s - bsdi_strings) + sizeof(bsdi_si);
                strcpy(s, osrelease);
                s += strlen(s) + 1;

                bsdi_si.bsdi_machine = (s - bsdi_strings) + sizeof(bsdi_si);
                strcpy(s, machine);
                s += strlen(s) + 1;

                needed = sizeof(bsdi_si) + (s - bsdi_strings);

                if ((uap->where == NULL) || (uap->size == NULL)) {
                        /* process is asking how much buffer to supply.. */
                        size = needed;
                        error = 0;
                        break;
                }

                if ((error = copyin(uap->size, &size, sizeof(size))) != 0)
                        break;

                /* if too much buffer supplied, trim it down */
                if (size > needed)
                        size = needed;

                /* how much of the buffer is remaining */
                left = size;

                if ((error = copyout((char *)&bsdi_si, uap->where, left)) != 0)
                        break;

                /* is there any point in continuing? */
                if (left > sizeof(bsdi_si)) {
                        left -= sizeof(bsdi_si);
                        error = copyout(&bsdi_strings,
                                        uap->where + sizeof(bsdi_si), left);
                }
                break;
        }

        default:
                error = EOPNOTSUPP;
                break;
        }
        if (error == 0) {
                td->td_retval[0] = needed ? needed : size;
                if (uap->size) {
                        error = copyout(&size, uap->size, sizeof(size));
                }
        }
        mtx_unlock(&Giant);
        return (error);
}
#endif /* COMPAT_43 */