fs/zfs/zfs_fuid.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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"@(#)zfs_fuid.c	1.3	08/01/04 SMI"

#include <sys/types.h>
#include <sys/unistd.h>
#include <sys/sysmacros.h>
#include <sys/sunddi.h>
#include <sys/zfs_vfsops.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_fuid.h>
#include <sys/dmu.h>
#include <sys/refcount.h>
#include <sys/avl.h>
#include <sys/zap.h>
#include <sys/nvpair.h>
#include <sys/kidmap.h>
#include <sys/sid.h>

/*
 * FUID Domain table(s).
 *
 * The FUID table is stored as a packed nvlist of an array
 * of nvlists which contain an index, domain string and offset
 *
 * During file system initialization the nvlist(s) are read and
 * two AVL trees are created.  One tree is keyed by the index number
 * and the other by the domain string.  Nodes are never removed from
 * trees, but new entries may be added.  If a new entry is added then the
 * on-disk packed nvlist will also be updated.
 */

#define	FUID_IDX	"fuid_idx"
#define	FUID_DOMAIN	"fuid_domain"
#define	FUID_OFFSET	"fuid_offset"
#define	FUID_NVP_ARRAY	"fuid_nvlist"

typedef struct fuid_domain {
	avl_node_t	f_node;
	ksiddomain_t	*f_ksid;
	int		f_idx;
	uint32_t	f_offset;
} fuid_domain_t;

typedef struct fuid_idx {
	avl_node_t	f_node;
	int		f_idx;
	fuid_domain_t	*f_domain;
} fuid_idx_t;

/*
 * Compare two indexes.
 */
static int
idx_compare(const void *arg1, const void *arg2)
{
	const fuid_idx_t *node1 = arg1;
	const fuid_idx_t *node2 = arg2;

	if (node1->f_idx < node2->f_idx)
		return (-1);
	else if (node1->f_idx > node2->f_idx)
		return (1);
	return (0);
}

/*
 * Compare two domain strings.
 */
static int
domain_compare(const void *arg1, const void *arg2)
{
	const fuid_domain_t *node1 = arg1;
	const fuid_domain_t *node2 = arg2;
	int val;

	val = strcmp(node1->f_ksid->kd_name, node2->f_ksid->kd_name);
	if (val == 0)
		return (0);
	return (val > 0 ? 1 : -1);
}

/*
 * Load the fuid table(s) into memory.
 */
static void
zfs_fuid_init(zfsvfs_t *zfsvfs, dmu_tx_t *tx)
{
	dmu_buf_t *db;
	char *packed;
	size_t nvsize = 0;
	int error = 0;
	int i;

	rw_enter(&zfsvfs->z_fuid_lock, RW_WRITER);

	if (zfsvfs->z_fuid_loaded) {
		rw_exit(&zfsvfs->z_fuid_lock);
		return;
	}

	if (zfsvfs->z_fuid_obj == 0) {

		/* first make sure we need to allocate object */

		error = zap_lookup(zfsvfs->z_os, MASTER_NODE_OBJ,
		    ZFS_FUID_TABLES, 8, 1, &zfsvfs->z_fuid_obj);
		if (error == ENOENT && tx != NULL) {
			zfsvfs->z_fuid_obj = dmu_object_alloc(zfsvfs->z_os,
			    DMU_OT_FUID, 1 << 14, DMU_OT_FUID_SIZE,
			    sizeof (uint64_t), tx);
			VERIFY(zap_add(zfsvfs->z_os, MASTER_NODE_OBJ,
			    ZFS_FUID_TABLES, sizeof (uint64_t), 1,
			    &zfsvfs->z_fuid_obj, tx) == 0);
		}
	}

	avl_create(&zfsvfs->z_fuid_idx, idx_compare,
	    sizeof (fuid_idx_t), offsetof(fuid_idx_t, f_node));
	avl_create(&zfsvfs->z_fuid_domain, domain_compare,
	    sizeof (fuid_domain_t), offsetof(fuid_domain_t, f_node));

	if (zfsvfs->z_fuid_obj) {
		VERIFY(0 == dmu_bonus_hold(zfsvfs->z_os, zfsvfs->z_fuid_obj,
		    FTAG, &db));
		nvsize = *(uint64_t *)db->db_data;
		dmu_buf_rele(db, FTAG);
	}

	if (nvsize == 0)
		goto initialized;

	packed = kmem_alloc(nvsize, KM_SLEEP);
	error = dmu_read(zfsvfs->z_os, zfsvfs->z_fuid_obj, 0, nvsize, packed);
	if (error == 0)  {
		nvlist_t **fuidnvp;
		nvlist_t *nvp = NULL;
		uint_t count;

		VERIFY(nvlist_unpack(packed, nvsize, &nvp, 0) == 0);
		VERIFY((error = nvlist_lookup_nvlist_array(nvp, FUID_NVP_ARRAY,
		    &fuidnvp, &count)) == 0);

		for (i = 0; i != count; i++) {
			fuid_idx_t *idxnode;
			fuid_domain_t *domnode;
			char *domain;
			avl_index_t loc;
			uint64_t idx, offset;

			VERIFY(nvlist_lookup_string(fuidnvp[i], FUID_DOMAIN,
			    &domain) == 0);
			VERIFY(nvlist_lookup_uint64(fuidnvp[i], FUID_IDX,
			    &idx) == 0);
			VERIFY(nvlist_lookup_uint64(fuidnvp[i], FUID_OFFSET,
			    &offset) == 0);

			idxnode = kmem_alloc(sizeof (fuid_idx_t), KM_SLEEP);
			domnode = kmem_alloc(sizeof (fuid_domain_t), KM_SLEEP);

			domnode->f_idx = idxnode->f_idx = idx;
			domnode->f_ksid = ksid_lookupdomain(domain);
			idxnode->f_domain = domnode;
			domnode->f_offset = offset;
			if (avl_find(&zfsvfs->z_fuid_idx,
			    idxnode, &loc) == NULL) {
				avl_insert(&zfsvfs->z_fuid_idx, idxnode, loc);
			}
			if (avl_find(&zfsvfs->z_fuid_domain,
			    domnode, &loc) == NULL) {
				avl_insert(&zfsvfs->z_fuid_domain,
				    domnode, loc);
			}
		}
		nvlist_free(nvp);
	}
	kmem_free(packed, nvsize);

initialized:
	zfsvfs->z_fuid_loaded = B_TRUE;
	rw_exit(&zfsvfs->z_fuid_lock);
}

/*
 * Query domain table for a given domain.
 *
 * If domain isn't found it is added to AVL trees and
 * the results are pushed out to disk.
 */
int
zfs_fuid_find_by_domain(zfsvfs_t *zfsvfs, const char *domain, char **retdomain,
    dmu_tx_t *tx)
{
	fuid_domain_t searchnode, *findnode;
	avl_index_t loc;

	/*
	 * If the dummy "nobody" domain then return an index of 0
	 * to cause the created FUID to be a standard POSIX id
	 * for the user nobody.
	 */
	if (domain[0] == '\0') {
		*retdomain = "";
		return (0);
	}

	searchnode.f_ksid = ksid_lookupdomain(domain);
	if (retdomain) {
		*retdomain = searchnode.f_ksid->kd_name;
	}
	if (zfsvfs->z_fuid_loaded == B_FALSE)
		zfs_fuid_init(zfsvfs, tx);

	rw_enter(&zfsvfs->z_fuid_lock, RW_READER);
	findnode = avl_find(&zfsvfs->z_fuid_domain, &searchnode, &loc);
	rw_exit(&zfsvfs->z_fuid_lock);

	if (findnode) {
		ksiddomain_rele(searchnode.f_ksid);
		return (findnode->f_idx);
	} else {
		fuid_domain_t *domnode;
		fuid_idx_t *newidxnode;
		nvlist_t *nvp;
		nvlist_t **fuids;
		uint64_t retidx;
		size_t nvsize = 0;
		char *packed;
		dmu_buf_t *db;
		int i = 0;

		domnode = kmem_alloc(sizeof (fuid_domain_t), KM_SLEEP);
		domnode->f_ksid = searchnode.f_ksid;
		domnode->f_offset = 0;

		newidxnode = kmem_alloc(sizeof (fuid_idx_t), KM_SLEEP);
		newidxnode->f_domain = domnode;

		rw_enter(&zfsvfs->z_fuid_lock, RW_WRITER);
		retidx = domnode->f_idx = newidxnode->f_idx =
		    avl_numnodes(&zfsvfs->z_fuid_idx) + 1;

		avl_add(&zfsvfs->z_fuid_domain, domnode);
		avl_add(&zfsvfs->z_fuid_idx, newidxnode);
		/*
		 * Now resync the on-disk nvlist.
		 */
		VERIFY(nvlist_alloc(&nvp, NV_UNIQUE_NAME, KM_SLEEP) == 0);

		domnode = avl_first(&zfsvfs->z_fuid_domain);
		fuids = kmem_alloc(retidx * sizeof (void *), KM_SLEEP);
		while (domnode) {
			VERIFY(nvlist_alloc(&fuids[i],
			    NV_UNIQUE_NAME, KM_SLEEP) == 0);
			VERIFY(nvlist_add_uint64(fuids[i], FUID_IDX,
			    domnode->f_idx) == 0);
			VERIFY(nvlist_add_uint64(fuids[i], FUID_OFFSET,
			    domnode->f_offset) == 0);
			VERIFY(nvlist_add_string(fuids[i++], FUID_DOMAIN,
			    domnode->f_ksid->kd_name) == 0);
			domnode = AVL_NEXT(&zfsvfs->z_fuid_domain, domnode);
		}
		VERIFY(nvlist_add_nvlist_array(nvp, FUID_NVP_ARRAY,
		    fuids, retidx) == 0);
		for (i = 0; i != retidx; i++)
			nvlist_free(fuids[i]);
		kmem_free(fuids, retidx * sizeof (void *));
		VERIFY(nvlist_size(nvp, &nvsize, NV_ENCODE_XDR) == 0);
		packed = kmem_alloc(nvsize, KM_SLEEP);
		VERIFY(nvlist_pack(nvp, &packed, &nvsize,
		    NV_ENCODE_XDR, KM_SLEEP) == 0);
		nvlist_free(nvp);
		dmu_write(zfsvfs->z_os, zfsvfs->z_fuid_obj, 0, nvsize,
		    packed, tx);
		kmem_free(packed, nvsize);
		VERIFY(0 == dmu_bonus_hold(zfsvfs->z_os, zfsvfs->z_fuid_obj,
		    FTAG, &db));
		dmu_buf_will_dirty(db, tx);
		*(uint64_t *)db->db_data = nvsize;
		dmu_buf_rele(db, FTAG);

		rw_exit(&zfsvfs->z_fuid_lock);
		return (retidx);
	}
}

/*
 * Query domain table by index, returning domain string
 *
 * Returns a pointer from an avl node of the domain string.
 *
 */
char *
zfs_fuid_find_by_idx(zfsvfs_t *zfsvfs, uint64_t idx)
{
	fuid_idx_t searchnode, *findnode;
	avl_index_t loc;

	if (idx == 0 || zfsvfs->z_use_fuids == B_FALSE)
		return (NULL);

	if (zfsvfs->z_fuid_loaded == B_FALSE)
		zfs_fuid_init(zfsvfs, NULL);

	searchnode.f_idx = idx;

	rw_enter(&zfsvfs->z_fuid_lock, RW_READER);
	findnode = avl_find(&zfsvfs->z_fuid_idx, &searchnode, &loc);
	rw_exit(&zfsvfs->z_fuid_lock);

	ASSERT(findnode);
	return (findnode->f_domain->f_ksid->kd_name);
}

void
zfs_fuid_get_mappings(zfs_fuid_hdl_t *hdl)
{
	VERIFY(hdl != NULL);
	if (hdl->z_map_needed == B_FALSE)
		return;

	(void) kidmap_get_mappings(hdl->z_hdl);

	kidmap_get_destroy(hdl->z_hdl);
	hdl->z_hdl = NULL;
	hdl->z_map_needed = B_FALSE;
}

void
zfs_fuid_queue_map_id(zfsvfs_t *zfsvfs, zfs_fuid_hdl_t *hdl,
    uint64_t fuid, cred_t *cr, zfs_fuid_type_t type, uid_t *id)
{
	uint32_t index = FUID_INDEX(fuid);
	char *domain;
	int status;

	VERIFY(hdl);

	if (index == 0 || zfsvfs->z_use_fuids == B_FALSE) {
		*id = (uid_t)fuid;
		return;
	}

	if (hdl->z_hdl == NULL) {
		hdl->z_hdl = kidmap_get_create(crgetzone(cr));
		hdl->z_map_needed = B_TRUE;
	}

	domain = zfs_fuid_find_by_idx(zfsvfs, index);
	ASSERT(domain != NULL);

	if (type == ZFS_OWNER || type == ZFS_ACE_USER)
		status = kidmap_batch_getuidbysid(hdl->z_hdl, domain,
		    FUID_RID(fuid), id, &hdl->z_status);
	else
		status = kidmap_batch_getgidbysid(hdl->z_hdl, domain,
		    FUID_RID(fuid), id, &hdl->z_status);
	ASSERT(status == 0);
}

void
zfs_fuid_map_ids(znode_t *zp, cred_t *cr, uid_t *uid, uid_t *gid)
{
	uint32_t uid_index = FUID_INDEX(zp->z_phys->zp_uid);
	uint32_t gid_index = FUID_INDEX(zp->z_phys->zp_gid);

	/* Favor the common case, neither will be ephemeral */
	if (uid_index == 0 && gid_index == 0) {
		*uid = zp->z_phys->zp_uid;
		*gid = zp->z_phys->zp_gid;
		return;
	} else {
		zfs_fuid_hdl_t hdl = { 0 };

		zfs_fuid_queue_map_id(zp->z_zfsvfs, &hdl,
		    zp->z_phys->zp_uid, cr, ZFS_OWNER, uid);

		zfs_fuid_queue_map_id(zp->z_zfsvfs, &hdl,
		    zp->z_phys->zp_gid, cr, ZFS_GROUP, gid);

		zfs_fuid_get_mappings(&hdl);
	}
}

void
zfs_fuid_map_id(zfsvfs_t *zfsvfs, uint64_t fuid,
    cred_t *cr, zfs_fuid_type_t type, uid_t *id)
{
	uint32_t index = FUID_INDEX(fuid);
	char *domain;

	if (index == 0) {
		*id = (uid_t)fuid;
		return;
	}

	domain = zfs_fuid_find_by_idx(zfsvfs, index);
	ASSERT(domain != NULL);

	if (type == ZFS_OWNER || type == ZFS_ACE_USER)
		(void) kidmap_getuidbysid(crgetzone(cr), domain,
		    FUID_RID(fuid), id);
	else
		(void) kidmap_getgidbysid(crgetzone(cr), domain,
		    FUID_RID(fuid), id);
}

/*
 * Add a FUID node to the list of fuid's being created for this
 * ACL
 *
 * If ACL has multiple domains, then keep only one copy of each unique
 * domain.
 */
static void
zfs_fuid_node_add(zfs_fuid_info_t **fuidpp, const char *domain, uint32_t rid,
    uint64_t idx, uint64_t id, zfs_fuid_type_t type)
{
	zfs_fuid_t *fuid;
	zfs_fuid_domain_t *fuid_domain;
	zfs_fuid_info_t *fuidp;
	uint64_t fuididx;
	boolean_t found = B_FALSE;

	if (*fuidpp == NULL)
		*fuidpp = zfs_fuid_info_alloc();

	fuidp = *fuidpp;
	/*
	 * First find fuid domain index in linked list
	 *
	 * If one isn't found then create an entry.
	 */

	for (fuididx = 1, fuid_domain = list_head(&fuidp->z_domains);
	    fuid_domain; fuid_domain = list_next(&fuidp->z_domains,
	    fuid_domain), fuididx++) {
		if (idx == fuid_domain->z_domidx) {
			found = B_TRUE;
			break;
		}
	}

	if (found == B_FALSE) {
		fuid_domain = kmem_alloc(sizeof (zfs_fuid_domain_t), KM_SLEEP);
		fuid_domain->z_domain = domain;
		fuid_domain->z_domidx = idx;
		list_insert_tail(&fuidp->z_domains, fuid_domain);
		fuidp->z_domain_str_sz += strlen(domain) + 1;
		fuidp->z_domain_cnt++;
	}

	if (type == ZFS_ACE_USER || type == ZFS_ACE_GROUP) {
		/*
		 * Now allocate fuid entry and add it on the end of the list
		 */

		fuid = kmem_alloc(sizeof (zfs_fuid_t), KM_SLEEP);
		fuid->z_id = id;
		fuid->z_domidx = idx;
		fuid->z_logfuid = FUID_ENCODE(fuididx, rid);

		list_insert_tail(&fuidp->z_fuids, fuid);
		fuidp->z_fuid_cnt++;
	} else {
		if (type == ZFS_OWNER)
			fuidp->z_fuid_owner = FUID_ENCODE(fuididx, rid);
		else
			fuidp->z_fuid_group = FUID_ENCODE(fuididx, rid);
	}
}

/*
 * Create a file system FUID, based on information in the users cred
 */
uint64_t
zfs_fuid_create_cred(zfsvfs_t *zfsvfs, uint64_t id,
    zfs_fuid_type_t type, dmu_tx_t *tx, cred_t *cr, zfs_fuid_info_t **fuidp)
{
	uint64_t	idx;
	ksid_t		*ksid;
	uint32_t	rid;
	char 		*kdomain;
	const char	*domain;

	VERIFY(type == ZFS_OWNER || type == ZFS_GROUP);

	if (zfsvfs->z_use_fuids == B_FALSE || !IS_EPHEMERAL(id))
		return ((uint64_t)id);

	ksid = crgetsid(cr, (type == ZFS_OWNER) ? KSID_OWNER : KSID_GROUP);

	VERIFY(ksid != NULL);
	rid = ksid_getrid(ksid);
	domain = ksid_getdomain(ksid);

	idx = zfs_fuid_find_by_domain(zfsvfs, domain, &kdomain, tx);

	zfs_fuid_node_add(fuidp, kdomain, rid, idx, id, type);

	return (FUID_ENCODE(idx, rid));
}

/*
 * Create a file system FUID for an ACL ace
 * or a chown/chgrp of the file.
 * This is similar to zfs_fuid_create_cred, except that
 * we can't find the domain + rid information in the
 * cred.  Instead we have to query Winchester for the
 * domain and rid.
 *
 * During replay operations the domain+rid information is
 * found in the zfs_fuid_info_t that the replay code has
 * attached to the zfsvfs of the file system.
 */
uint64_t
zfs_fuid_create(zfsvfs_t *zfsvfs, uint64_t id, cred_t *cr,
    zfs_fuid_type_t type, dmu_tx_t *tx, zfs_fuid_info_t **fuidpp)
{
	const char *domain;
	char *kdomain;
	uint32_t fuid_idx = FUID_INDEX(id);
	uint32_t rid;
	idmap_stat status;
	uint64_t idx;
	boolean_t is_replay = (zfsvfs->z_assign >= TXG_INITIAL);
	zfs_fuid_t *zfuid = NULL;
	zfs_fuid_info_t *fuidp;

	/*
	 * If POSIX ID, or entry is already a FUID then
	 * just return the id
	 */
	if (!IS_EPHEMERAL(id) || fuid_idx != 0)
		return (id);

	if (is_replay) {
		fuidp = zfsvfs->z_fuid_replay;

		/*
		 * If we are passed an ephemeral id, but no
		 * fuid_info was logged then return NOBODY.
		 * This is most likely a result of idmap service
		 * not being available.
		 */
		if (fuidp == NULL)
			return (UID_NOBODY);

		switch (type) {
		case ZFS_ACE_USER:
		case ZFS_ACE_GROUP:
			zfuid = list_head(&fuidp->z_fuids);
			rid = FUID_RID(zfuid->z_logfuid);
			idx = FUID_INDEX(zfuid->z_logfuid);
			break;
		case ZFS_OWNER:
			rid = FUID_RID(fuidp->z_fuid_owner);
			idx = FUID_INDEX(fuidp->z_fuid_owner);
			break;
		case ZFS_GROUP:
			rid = FUID_RID(fuidp->z_fuid_group);
			idx = FUID_INDEX(fuidp->z_fuid_group);
			break;
		};
		domain = fuidp->z_domain_table[idx -1];
	} else {
		if (type == ZFS_OWNER || type == ZFS_ACE_USER)
			status = kidmap_getsidbyuid(crgetzone(cr), id,
			    &domain, &rid);
		else
			status = kidmap_getsidbygid(crgetzone(cr), id,
			    &domain, &rid);

		if (status != 0) {
			/*
			 * When returning nobody we will need to
			 * make a dummy fuid table entry for logging
			 * purposes.
			 */
			rid = UID_NOBODY;
			domain = "";
		}

	}

	idx = zfs_fuid_find_by_domain(zfsvfs, domain, &kdomain, tx);

	if (is_replay == B_FALSE)
		zfs_fuid_node_add(fuidpp, kdomain, rid, idx, id, type);
	else if (zfuid != NULL) {
		list_remove(&fuidp->z_fuids, zfuid);
		kmem_free(zfuid, sizeof (zfs_fuid_t));
	}
	return (FUID_ENCODE(idx, rid));
}

void
zfs_fuid_destroy(zfsvfs_t *zfsvfs)
{
	fuid_domain_t *domnode;
	fuid_idx_t *idxnode;
	void *cookie;

	rw_enter(&zfsvfs->z_fuid_lock, RW_WRITER);
	if (zfsvfs->z_fuid_loaded == B_FALSE) {
		rw_exit(&zfsvfs->z_fuid_lock);
		return;
	}
	cookie = NULL;
	while (domnode = avl_destroy_nodes(&zfsvfs->z_fuid_domain, &cookie)) {
		ksiddomain_rele(domnode->f_ksid);
		kmem_free(domnode, sizeof (fuid_domain_t));
	}
	avl_destroy(&zfsvfs->z_fuid_domain);
	cookie = NULL;
	while (idxnode = avl_destroy_nodes(&zfsvfs->z_fuid_idx, &cookie))
		kmem_free(idxnode, sizeof (fuid_idx_t));
	avl_destroy(&zfsvfs->z_fuid_idx);
	rw_exit(&zfsvfs->z_fuid_lock);
}

/*
 * Allocate zfs_fuid_info for tracking FUIDs created during
 * zfs_mknode, VOP_SETATTR() or VOP_SETSECATTR()
 */
zfs_fuid_info_t *
zfs_fuid_info_alloc(void)
{
	zfs_fuid_info_t *fuidp;

	fuidp = kmem_zalloc(sizeof (zfs_fuid_info_t), KM_SLEEP);
	list_create(&fuidp->z_domains, sizeof (zfs_fuid_domain_t),
	    offsetof(zfs_fuid_domain_t, z_next));
	list_create(&fuidp->z_fuids, sizeof (zfs_fuid_t),
	    offsetof(zfs_fuid_t, z_next));
	return (fuidp);
}

/*
 * Release all memory associated with zfs_fuid_info_t
 */
void
zfs_fuid_info_free(zfs_fuid_info_t *fuidp)
{
	zfs_fuid_t *zfuid;
	zfs_fuid_domain_t *zdomain;

	while ((zfuid = list_head(&fuidp->z_fuids)) != NULL) {
		list_remove(&fuidp->z_fuids, zfuid);
		kmem_free(zfuid, sizeof (zfs_fuid_t));
	}

	if (fuidp->z_domain_table != NULL)
		kmem_free(fuidp->z_domain_table,
		    (sizeof (char **)) * fuidp->z_domain_cnt);

	while ((zdomain = list_head(&fuidp->z_domains)) != NULL) {
		list_remove(&fuidp->z_domains, zdomain);
		kmem_free(zdomain, sizeof (zfs_fuid_domain_t));
	}

	kmem_free(fuidp, sizeof (zfs_fuid_info_t));
}

/*
 * Check to see if id is a groupmember.  If cred
 * has ksid info then sidlist is checked first
 * and if still not found then POSIX groups are checked
 *
 * Will use a straight FUID compare when possible.
 */
boolean_t
zfs_groupmember(zfsvfs_t *zfsvfs, uint64_t id, cred_t *cr)
{
	ksid_t		*ksid = crgetsid(cr, KSID_GROUP);
	uid_t		gid;

	if (ksid) {
		int 		i;
		ksid_t		*ksid_groups;
		ksidlist_t	*ksidlist = crgetsidlist(cr);
		uint32_t	idx = FUID_INDEX(id);
		uint32_t	rid = FUID_RID(id);

		ASSERT(ksidlist);
		ksid_groups = ksidlist->ksl_sids;

		for (i = 0; i != ksidlist->ksl_nsid; i++) {
			if (idx == 0) {
				if (id != IDMAP_WK_CREATOR_GROUP_GID &&
				    id == ksid_groups[i].ks_id) {
					return (B_TRUE);
				}
			} else {
				char *domain;

				domain = zfs_fuid_find_by_idx(zfsvfs, idx);
				ASSERT(domain != NULL);

				if (strcmp(domain,
				    IDMAP_WK_CREATOR_SID_AUTHORITY) == 0) {
					return (B_FALSE);
				}

				if ((strcmp(domain,
				    ksid_groups[i].ks_domain->kd_name) == 0) &&
				    rid == ksid_groups[i].ks_rid) {
					return (B_TRUE);
				}
			}
		}
	}

	/*
	 * Not found in ksidlist, check posix groups
	 */
	zfs_fuid_map_id(zfsvfs, id, cr, ZFS_GROUP, &gid);
	return (groupmember(gid, cr));
}