kern_sysctl.c

RTEMS (Real-Time Executive for Multiprocessor Systems) is a free open source real-time operating sys

/*-
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 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
 * $FreeBSD: src/sys/kern/kern_sysctl.c,v 1.135 2002/10/27 07:12:34 rwatson Exp $
 */

#ifndef __rtems__
#include "opt_compat.h"
#include "opt_mac.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#ifndef __rtems__
#include <sys/mac.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/sysproto.h>
#else
#include <sys/buf.h>

#include <stdio.h>                                /* for snprintf() */
size_t   strlcpy(char *, const char *, size_t);
#endif
#include <vm/vm.h>
#include <vm/vm_extern.h>

#ifndef __rtems__
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");
#else
/*
 * Currently these mean nothing on RTEMS.
 */
#define M_SYSCTLOID 1
#define M_SYSCTLTMP 2
#define M_ZERO      0

typedef unsigned long *uintptr_t;

#define mtx_lock(l)
#define mtx_unlock(l)

#endif

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

#ifdef __rtems__
#define	SYSCTL_LOCK()
#define	SYSCTL_UNLOCK()
#define	SYSCTL_INIT()
#else
#define	SYSCTL_LOCK()		sx_xlock(&sysctllock)
#define	SYSCTL_UNLOCK()		sx_xunlock(&sysctllock)
#define	SYSCTL_INIT()		sx_init(&sysctllock, "sysctl sysctllock")
#endif

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)
{
	SLIST_REMOVE(oidp->oid_parent, oidp, sysctl_oid, oid_link);
}

/* 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->descr)
				free((void *)(uintptr_t)(const void *)oidp->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(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->descr = malloc(len, M_SYSCTLOID, M_WAITOK);
		if (oidp->descr)
			strcpy((char *)(uintptr_t)(const void *)oidp->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);
}

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

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.
 */

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)
{
#ifndef __rtems__
	int error;

	error = suser(req->td);
	if (error)
		return error;
#endif
	sysctl_sysctl_debug_dump_node(&sysctl__children, 0);
	return ENOENT;
}

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