common/os/sid.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

/*
 * Sid manipulation (stubs).
 */

#include <sys/atomic.h>
#include <sys/avl.h>
#include <sys/cmn_err.h>
#include <sys/kmem.h>
#include <sys/mutex.h>
#include <sys/sid.h>
#include <sys/sysmacros.h>
#include <sys/systm.h>

static kmutex_t sid_lock;
static avl_tree_t sid_tree;
static boolean_t sid_inited = B_FALSE;

static ksiddomain_t
*ksid_enterdomain(const char *dom)
{
	size_t len = strlen(dom) + 1;
	ksiddomain_t *res;

	ASSERT(MUTEX_HELD(&sid_lock));
	res = kmem_alloc(sizeof (ksiddomain_t), KM_SLEEP);
	res->kd_len = (uint_t)len;
	res->kd_name = kmem_alloc(len, KM_SLEEP);
	bcopy(dom, res->kd_name, len);

	res->kd_ref = 1;

	avl_add(&sid_tree, res);

	return (res);
}

void
ksid_hold(ksid_t *ks)
{
	if (ks->ks_domain != NULL)
		ksiddomain_hold(ks->ks_domain);
}

void
ksid_rele(ksid_t *ks)
{
	if (ks->ks_domain != NULL)
		ksiddomain_rele(ks->ks_domain);
}

void
ksiddomain_hold(ksiddomain_t *kd)
{
	atomic_add_32(&kd->kd_ref, 1);
}

void
ksiddomain_rele(ksiddomain_t *kd)
{
	if (atomic_add_32_nv(&kd->kd_ref, -1) == 0) {
		/*
		 * The kd reference can only be incremented from 0 when
		 * the sid_lock is held; so we lock and then check need to
		 * check for 0 again.
		 */
		mutex_enter(&sid_lock);
		if (kd->kd_ref == 0) {
			avl_remove(&sid_tree, kd);
			kmem_free(kd->kd_name, kd->kd_len);
			kmem_free(kd, sizeof (*kd));
		}
		mutex_exit(&sid_lock);
	}
}

void
ksidlist_hold(ksidlist_t *ksl)
{
	atomic_add_32(&ksl->ksl_ref, 1);
}

void
ksidlist_rele(ksidlist_t *ksl)
{
	if (atomic_add_32_nv(&ksl->ksl_ref, -1) == 0) {
		int i;

		for (i = 0; i < ksl->ksl_nsid; i++)
			ksid_rele(&ksl->ksl_sids[i]);

		kmem_free(ksl, KSIDLIST_MEM(ksl->ksl_nsid));
	}
}

static int
ksid_cmp(const void *a, const void *b)
{
	const ksiddomain_t *ap = a;
	const ksiddomain_t *bp = b;
	int res;

	res = strcmp(ap->kd_name, bp->kd_name);
	if (res > 0)
		return (1);
	if (res != 0)
		return (-1);
	return (0);
}

/*
 * Lookup the named domain in the AVL tree.
 * If no entry is found, add the domain to the AVL tree.
 * The domain is returned held and needs to be released
 * when done.
 */
ksiddomain_t
*ksid_lookupdomain(const char *dom)
{
	ksiddomain_t *res;
	ksiddomain_t tmpl;

	mutex_enter(&sid_lock);

	if (!sid_inited) {
		avl_create(&sid_tree, ksid_cmp, sizeof (ksiddomain_t),
		    offsetof(ksiddomain_t, kd_link));

		res = ksid_enterdomain(dom);
		sid_inited = B_TRUE;
		mutex_exit(&sid_lock);
		return (res);
	}

	tmpl.kd_name = (char *)dom;

	res = avl_find(&sid_tree, &tmpl, NULL);
	if (res == NULL) {
		res = ksid_enterdomain(dom);
	} else {
		ksiddomain_hold(res);
	}

	mutex_exit(&sid_lock);
	return (res);
}

const char *
ksid_getdomain(ksid_t *ks)
{
	return (ks->ks_domain->kd_name);
}

uint_t
ksid_getrid(ksid_t *ks)
{
	return (ks->ks_rid);
}

int
ksid_lookup(uid_t id, ksid_t *res)
{
	uid_t tmp;

	if (idmap_call_byid(id, res) == -1)
		return (-1);

	tmp = idmap_call_bysid(res);
	if (tmp != id)
		cmn_err(CE_WARN, "The idmapper has gone bonkers");
	res->ks_id = id;

	return (0);
}

credsid_t *
kcrsid_alloc(void)
{
	credsid_t *kcr = kmem_zalloc(sizeof (*kcr), KM_SLEEP);
	kcr->kr_ref = 1;
	return (kcr);
}

/*
 * Returns a credsid_t with a refcount of 1.
 */
static credsid_t *
kcrsid_dup(credsid_t *org)
{
	credsid_t *new;
	ksid_index_t ki;

	if (org == NULL)
		return (kcrsid_alloc());
	if (org->kr_ref == 1)
		return (org);
	new = kcrsid_alloc();

	/* Copy, then update reference counts */
	*new = *org;
	new->kr_ref = 1;
	for (ki = 0; ki < KSID_COUNT; ki++)
		ksid_hold(&new->kr_sidx[ki]);

	if (new->kr_sidlist != NULL)
		ksidlist_hold(new->kr_sidlist);

	kcrsid_rele(org);
	return (new);
}

void
kcrsid_hold(credsid_t *kcr)
{
	atomic_add_32(&kcr->kr_ref, 1);
}

void
kcrsid_rele(credsid_t *kcr)
{
	if (atomic_add_32_nv(&kcr->kr_ref, -1) == 0) {
		ksid_index_t i;

		for (i = 0; i < KSID_COUNT; i++)
			ksid_rele(&kcr->kr_sidx[i]);

		if (kcr->kr_sidlist != NULL)
			ksidlist_rele(kcr->kr_sidlist);

		kmem_free(kcr, sizeof (*kcr));
	}
}

/*
 * Copy the SID credential into a previously allocated piece of memory.
 */
void
kcrsidcopy_to(const credsid_t *okcr, credsid_t *nkcr)
{
	int i;

	ASSERT(nkcr->kr_ref == 1);

	if (okcr == NULL)
		return;
	*nkcr = *okcr;
	for (i = 0; i < KSID_COUNT; i++)
		ksid_hold(&nkcr->kr_sidx[i]);
	if (nkcr->kr_sidlist != NULL)
		ksidlist_hold(nkcr->kr_sidlist);
	nkcr->kr_ref = 1;
}

static int
kcrsid_sidcount(const credsid_t *kcr)
{
	int cnt = 0;
	int i;

	if (kcr == NULL)
		return (0);

	for (i = 0; i < KSID_COUNT; i++)
		if (kcr->kr_sidx[i].ks_domain != NULL)
			cnt++;

	if (kcr->kr_sidlist != NULL)
		cnt += kcr->kr_sidlist->ksl_nsid;
	return (cnt);
}

/*
 * Argument needs to be a ksid_t with a properly held ks_domain reference.
 */
credsid_t *
kcrsid_setsid(credsid_t *okcr, ksid_t *ksp, ksid_index_t i)
{
	int ocnt = kcrsid_sidcount(okcr);
	credsid_t *nkcr;

	/*
	 * Unset the particular ksid; if there are no other SIDs or if this
	 * is the last SID, remove the auxilary data structure.
	 */
	if (ksp == NULL) {
		if (ocnt == 0 ||
		    (ocnt == 1 && okcr->kr_sidx[i].ks_domain != NULL)) {
			if (okcr != NULL)
				kcrsid_rele(okcr);
			return (NULL);
		}
	}
	nkcr = kcrsid_dup(okcr);
	ksid_rele(&nkcr->kr_sidx[i]);
	if (ksp == NULL)
		bzero(&nkcr->kr_sidx[i], sizeof (ksid_t));
	else
		nkcr->kr_sidx[i] = *ksp;

	return (nkcr);
}

/*
 * Argument needs to be a ksidlist_t with properly held ks_domain references
 * and a reference count taking the new reference into account.
 */
credsid_t *
kcrsid_setsidlist(credsid_t *okcr, ksidlist_t *ksl)
{
	int ocnt = kcrsid_sidcount(okcr);
	credsid_t *nkcr;

	/*
	 * Unset the sidlist; if there are no further SIDs, remove the
	 * auxilary data structure.
	 */
	if (ksl == NULL) {
		if (ocnt == 0 || (okcr->kr_sidlist != NULL &&
		    ocnt == okcr->kr_sidlist->ksl_nsid)) {
			if (okcr != NULL)
				kcrsid_rele(okcr);
			return (NULL);
		}
	}
	nkcr = kcrsid_dup(okcr);
	if (nkcr->kr_sidlist != NULL)
		ksidlist_rele(nkcr->kr_sidlist);

	nkcr->kr_sidlist = ksl;
	return (nkcr);
}

ksidlist_t *
kcrsid_gidstosids(int ngrp, gid_t *grp)
{
	int i;
	ksidlist_t *list;
	int cnt;

	if (ngrp == 0)
		return (NULL);

	cnt = 0;
	list = kmem_zalloc(KSIDLIST_MEM(ngrp), KM_SLEEP);

	list->ksl_nsid = ngrp;
	list->ksl_ref = 1;

	for (i = 0; i < ngrp; i++) {
		if (grp[i] > MAXUID) {
			list->ksl_neid++;
			if (ksid_lookup(grp[i], &list->ksl_sids[i]) != 0) {
				while (--i >= 0)
					ksid_rele(&list->ksl_sids[i]);
				cnt = 0;
				break;
			}
			cnt++;
		} else {
			list->ksl_sids[i].ks_id = grp[i];
		}
	}
	if (cnt == 0) {
		kmem_free(list, KSIDLIST_MEM(ngrp));
		return (NULL);
	}
	return (list);
}