/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (C) 2013, Trustees of Indiana University
 * Author: Joshua Walgenbach <jjw@iu.edu>
 */
#include <linux/module.h>
#include <lustre_net.h>
#include "nodemap_internal.h"

#define HASH_NODEMAP_BKT_BITS 3
#define HASH_NODEMAP_CUR_BITS 3
#define HASH_NODEMAP_MAX_BITS 7

#define DEFAULT_NODEMAP "default"

/* nodemap proc root proc directory under fs/lustre */
struct proc_dir_entry *proc_lustre_nodemap_root;

/* Highest numerical lu_nodemap.nm_id defined */
static atomic_t nodemap_highest_id;

/* Simple flag to determine if nodemaps are active */
bool nodemap_active;

/**
 * pointer to default nodemap kept to keep from
 * lookup it up in the hash since it is needed
 * more often
 */
static struct lu_nodemap *default_nodemap;

/**
 * Hash keyed on nodemap name containing all
 * nodemaps
 */
static cfs_hash_t *nodemap_hash;

/**
 * Nodemap destructor
 *
 * \param	nodemap		nodemap to destroy
 */
static void nodemap_destroy(struct lu_nodemap *nodemap)
{
	struct lu_nid_range *range;
	struct lu_nid_range *temp;

	list_for_each_entry_safe(range, temp, &nodemap->nm_ranges,
				 rn_list) {
		range_delete(range);
	}

	idmap_delete_tree(nodemap);

	lprocfs_remove(&nodemap->nm_proc_entry);
	OBD_FREE_PTR(nodemap);
}

/**
 * Functions used for the cfs_hash
 */
static void nodemap_getref(struct lu_nodemap *nodemap)
{
	CDEBUG(D_INFO, "nodemap %p\n", nodemap);
	atomic_inc(&nodemap->nm_refcount);
}

void nodemap_putref(struct lu_nodemap *nodemap)
{
	LASSERT(nodemap != NULL);
	LASSERT(atomic_read(&nodemap->nm_refcount) > 0);

	if (atomic_dec_and_test(&nodemap->nm_refcount))
		nodemap_destroy(nodemap);
}

static __u32 nodemap_hashfn(cfs_hash_t *hash_body,
			    const void *key, unsigned mask)
{
	const struct lu_nodemap *nodemap = key;

	return cfs_hash_djb2_hash(nodemap->nm_name, strlen(nodemap->nm_name),
				  mask);
}

static void *nodemap_hs_key(cfs_hlist_node_t *hnode)
{
	struct lu_nodemap *nodemap;

	nodemap = cfs_hlist_entry(hnode, struct lu_nodemap, nm_hash);

	return nodemap->nm_name;
}

static int nodemap_hs_keycmp(const void *key,
			     cfs_hlist_node_t *compared_hnode)
{
	struct lu_nodemap *nodemap;

	nodemap = nodemap_hs_key(compared_hnode);

	return !strcmp(key, nodemap->nm_name);
}

static void *nodemap_hs_hashobject(cfs_hlist_node_t *hnode)
{
	return cfs_hlist_entry(hnode, struct lu_nodemap, nm_hash);
}

static void nodemap_hs_get(cfs_hash_t *hs, cfs_hlist_node_t *hnode)
{
	struct lu_nodemap *nodemap;

	nodemap = cfs_hlist_entry(hnode, struct lu_nodemap, nm_hash);
	nodemap_getref(nodemap);
}

static void nodemap_hs_put_locked(cfs_hash_t *hs,
				  cfs_hlist_node_t *hnode)
{
	struct lu_nodemap *nodemap;

	nodemap = cfs_hlist_entry(hnode, struct lu_nodemap, nm_hash);
	nodemap_putref(nodemap);
}

static cfs_hash_ops_t nodemap_hash_operations = {
	.hs_hash	= nodemap_hashfn,
	.hs_key		= nodemap_hs_key,
	.hs_keycmp	= nodemap_hs_keycmp,
	.hs_object	= nodemap_hs_hashobject,
	.hs_get		= nodemap_hs_get,
	.hs_put_locked	= nodemap_hs_put_locked,
};

/* end of cfs_hash functions */

/**
 * Helper iterator to clean up nodemap on module exit.
 *
 * \param	hs		hash structure
 * \param	bd		bucket descriptor
 * \param	hnode		hash node
 * \param	data		not used here
 */
static int nodemap_cleanup_iter_cb(cfs_hash_t *hs, cfs_hash_bd_t *bd,
				   cfs_hlist_node_t *hnode, void *data)
{
	struct lu_nodemap *nodemap;

	nodemap = cfs_hlist_entry(hnode, struct lu_nodemap, nm_hash);
	nodemap_putref(nodemap);

	return 0;
}

/**
 * Walk the nodemap_hash and remove all nodemaps.
 */
void nodemap_cleanup_all(void)
{
	cfs_hash_for_each_safe(nodemap_hash, nodemap_cleanup_iter_cb, NULL);
	cfs_hash_putref(nodemap_hash);
}

/**
 * Initialize nodemap_hash
 *
 * \retval	0		success
 * \retval	-ENOMEM		cannot create hash
 */
static int nodemap_init_hash(void)
{
	nodemap_hash = cfs_hash_create("NODEMAP", HASH_NODEMAP_CUR_BITS,
				       HASH_NODEMAP_MAX_BITS,
				       HASH_NODEMAP_BKT_BITS, 0,
				       CFS_HASH_MIN_THETA,
				       CFS_HASH_MAX_THETA,
				       &nodemap_hash_operations,
				       CFS_HASH_DEFAULT);

	if (nodemap_hash == NULL) {
		CERROR("cannot create nodemap_hash table\n");
		return -ENOMEM;
	}

	return 0;
}

/**
 * Check for valid nodemap name
 *
 * \param	name		nodemap name
 * \retval	true		valid
 * \retval	false		invalid
 */
static bool nodemap_name_is_valid(const char *name)
{
	if (strlen(name) > LUSTRE_NODEMAP_NAME_LENGTH ||
	    strlen(name) == 0)
		return false;

	for (; *name != '\0'; name++) {
		if (!isalnum(*name) && *name != '_')
			return false;
	}
	return true;
}

/**
 * Nodemap lookup
 *
 * Look nodemap up in the nodemap hash
 *
 * \param	name		name of nodemap
 * \param	nodemap		found nodemap or NULL
 * \retval	lu_nodemap	named nodemap
 * \retval	NULL		nodemap doesn't exist
 */
static int nodemap_lookup(const char *name, struct lu_nodemap **nodemap)
{
	int rc = 0;

	*nodemap = NULL;

	if (!nodemap_name_is_valid(name))
		GOTO(out, rc = -EINVAL);

	*nodemap = cfs_hash_lookup(nodemap_hash, name);
	if (*nodemap == NULL)
		rc = -ENOENT;

out:
	return rc;
}

/**
 * classify the nid into the proper nodemap
 *
 * \param	nid			nid to classify
 * \retval	nodemap			nodemap containing the nid
 * \retval	default_nodemap		default nodemap
 */
struct lu_nodemap *nodemap_classify_nid(lnet_nid_t nid)
{
	struct lu_nid_range	*range;

	range = range_search(nid);
	if (range != NULL)
		return range->rn_nodemap;

	return default_nodemap;
}
EXPORT_SYMBOL(nodemap_classify_nid);

/**
 * simple check for default nodemap
 */
static bool is_default_nodemap(const struct lu_nodemap *nodemap)
{
	return nodemap->nm_id == 0;
}

/**
 * parse a nodemap range string into two nids
 *
 * \param	range_str		string to parse
 * \param	range[2]		array of two nids
 * \reyval	0 on success
 */
int nodemap_parse_range(const char *range_str, lnet_nid_t range[2])
{
	char	buf[LNET_NIDSTR_SIZE * 2 + 2];
	char	*ptr = NULL;
	char    *start_nidstr;
	char    *end_nidstr;
	int     rc = 0;

	snprintf(buf, sizeof(buf), "%s", range_str);
	ptr = buf;
	start_nidstr = strsep(&ptr, ":");
	end_nidstr = strsep(&ptr, ":");

	if (start_nidstr == NULL || end_nidstr == NULL)
		GOTO(out, rc = -EINVAL);

	range[0] = libcfs_str2nid(start_nidstr);
	range[1] = libcfs_str2nid(end_nidstr);

out:
	return rc;

}
EXPORT_SYMBOL(nodemap_parse_range);

/**
 * parse a string containing an id map of form "client_id:filesystem_id"
 * into an array of __u32 * for use in mapping functions
 *
 * \param	idmap_str		map string
 * \param	idmap			array[2] of __u32
 *
 * \retval	0 on success
 */
int nodemap_parse_idmap(const char *idmap_str, __u32 idmap[2])
{
	char	*end;

	if (idmap_str == NULL)
		return -EINVAL;

	idmap[0] = simple_strtoul(idmap_str, &end, 10);
	if (end == idmap_str || *end != ':')
		return -EINVAL;

	idmap_str = end + 1;
	idmap[1] = simple_strtoul(idmap_str, &end, 10);
	if (end == idmap_str)
		return -EINVAL;

	return 0;
}
EXPORT_SYMBOL(nodemap_parse_idmap);

/**
 * add an idmap to the proper nodemap trees
 *
 * \param	name		name of nodemap
 * \param	id_type		NODEMAP_UID or NODEMAP_GID
 * \param	map		array[2] __u32 containing the mapA values
 *				map[0] is client id
 *				map[1] is the filesystem id
 *
 * \retval	0 on success
 */
int nodemap_add_idmap(const char *name, enum nodemap_id_type id_type,
		      const __u32 map[2])
{
	struct lu_nodemap	*nodemap = NULL;
	struct lu_idmap		*idmap;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL || is_default_nodemap(nodemap))
		GOTO(out, rc = -EINVAL);

	idmap = idmap_create(map[0], map[1]);
	if (idmap == NULL)
		GOTO(out_putref, rc = -ENOMEM);

	idmap_insert(id_type, idmap, nodemap);

out_putref:
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_add_idmap);

/**
 * delete idmap from proper nodemap tree
 *
 * \param	name		name of nodemap
 * \param	id_type		NODEMAP_UID or NODEMAP_GID
 * \param	map		array[2] __u32 containing the mapA values
 *				map[0] is client id
 *				map[1] is the filesystem id
 *
 * \retval	0 on success
 */
int nodemap_del_idmap(const char *name, enum nodemap_id_type id_type,
		      const __u32 map[2])
{
	struct lu_nodemap	*nodemap = NULL;
	struct lu_idmap		*idmap = NULL;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL || is_default_nodemap(nodemap))
		GOTO(out, rc = -EINVAL);

	idmap = idmap_search(nodemap, NODEMAP_CLIENT_TO_FS, id_type,
			     map[0]);
	if (idmap == NULL)
		GOTO(out_putref, rc = -EINVAL);

	idmap_delete(id_type, idmap, nodemap);

out_putref:
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_del_idmap);

/**
 * mapping function for nodemap idmaps
 *
 * \param	nodemap		lu_nodemap structure defining nodemap
 * \param	node_type	NODEMAP_UID or NODEMAP_GID
 * \param	tree_type	NODEMAP_CLIENT_TO_FS or
 *				NODEMAP_FS_TO_CLIENT
 * \param	id		id to map
 *
 * \retval	mapped id according to the rules below.
 *
 * if the nodemap_active is false, just return the passed id without mapping
 *
 * if the id to be looked up in 0, check that root access is allowed and if it
 * is, return 0. Otherwise, return the squash uid or gid.
 *
 * if the nodemap is configured to trusted the ids from the client system, just
 * return the passwd id without mapping.
 *
 * if by this point, we haven't returned and the nodemap in question is the
 * default nodemap, return the dquash uid or gid.
 *
 * after these checks, search the proper tree for the mapping, and if found
 * return the mapped value, otherwise return the squash uid or gid.
 */
__u32 nodemap_map_id(struct lu_nodemap *nodemap,
		     enum nodemap_id_type id_type,
		     enum nodemap_tree_type tree_type, __u32 id)
{
	struct lu_idmap		*idmap = NULL;

	if (!nodemap_active)
		goto out;

	if (id == 0) {
		if (nodemap->nmf_allow_root_access)
			goto out;
		else
			goto squash;
	}

	if (nodemap->nmf_trust_client_ids)
		goto out;

	if (is_default_nodemap(nodemap))
		goto squash;

	idmap = idmap_search(nodemap, tree_type, id_type, id);
	if (idmap == NULL)
		goto squash;

	if (tree_type == NODEMAP_FS_TO_CLIENT)
		return idmap->id_client;

	return idmap->id_fs;

squash:
	if (id_type == NODEMAP_UID)
		return nodemap->nm_squash_uid;
	else
		return nodemap->nm_squash_gid;
out:
	return id;
}
EXPORT_SYMBOL(nodemap_map_id);

/*
 * add nid range to nodemap
 * \param	name		nodemap name
 * \param	range_st	string containing nid range
 * \retval	0 on success
 *
 * add an range to the global range tree and attached the
 * range to the named nodemap.
 */
int nodemap_add_range(const char *name, const lnet_nid_t nid[2])
{
	struct lu_nodemap	*nodemap = NULL;
	struct lu_nid_range	*range;
	int rc;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL || is_default_nodemap(nodemap))
		GOTO(out, rc = -EINVAL);

	range = range_create(nid[0], nid[1], nodemap);
	if (range == NULL)
		GOTO(out_putref, rc = -ENOMEM);

	rc = range_insert(range);
	if (rc != 0) {
		CERROR("cannot insert nodemap range into '%s': rc = %d\n",
		      nodemap->nm_name, rc);
		list_del(&range->rn_list);
		range_destroy(range);
		GOTO(out_putref, rc = -ENOMEM);
	}

	list_add(&range->rn_list, &nodemap->nm_ranges);

out_putref:
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_add_range);

/**
 * delete a range
 * \param	name		nodemap name
 * \param	range_str	string containing range
 * \retval	0 on success
 *
 * Delete range from global range tree, and remove it
 * from the list in the associated nodemap.
 */
int nodemap_del_range(const char *name, const lnet_nid_t nid[2])
{
	struct lu_nodemap	*nodemap;
	struct lu_nid_range	*range;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL || is_default_nodemap(nodemap))
		GOTO(out, rc = -EINVAL);

	range = range_find(nid[0], nid[1]);
	if (range == NULL)
		GOTO(out_putref, rc = -EINVAL);

	range_delete(range);

out_putref:
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_del_range);

/**
 * Nodemap constructor
 *
 * Creates an lu_nodemap structure and assigns sane default
 * member values. If this is the default nodemap, the defaults
 * are the most restictive in xterms of mapping behavior. Otherwise
 * the default flags should be inherited from the default nodemap.
 * The adds nodemap to nodemap_hash.
 *
 * \param	name		name of nodemap
 * \param	is_default	true if default nodemap
 * \retval	0		success
 * \retval	-EINVAL		invalid nodemap name
 * \retval	-EEXIST		nodemap already exists
 * \retval	-ENOMEM		cannot allocate memory for nodemap
 */
static int nodemap_create(const char *name, bool is_default)
{
	struct	lu_nodemap *nodemap = NULL;
	int	rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (rc == -EINVAL)
		goto out;

	if (rc != -ENOENT) {
		nodemap_putref(nodemap);
		GOTO(out, rc = -EEXIST);
	}
	OBD_ALLOC_PTR(nodemap);

	if (nodemap == NULL) {
		CERROR("cannot allocate memory (%zu bytes)"
		       "for nodemap '%s'\n", sizeof(*nodemap),
		       name);
		GOTO(out, rc = -ENOMEM);
	}

	snprintf(nodemap->nm_name, sizeof(nodemap->nm_name), "%s", name);

	INIT_LIST_HEAD(&(nodemap->nm_ranges));
	nodemap->nm_fs_to_client_uidmap = RB_ROOT;
	nodemap->nm_client_to_fs_uidmap = RB_ROOT;
	nodemap->nm_fs_to_client_gidmap = RB_ROOT;
	nodemap->nm_client_to_fs_gidmap = RB_ROOT;

	if (is_default) {
		nodemap->nm_id = LUSTRE_NODEMAP_DEFAULT_ID;
		nodemap->nmf_trust_client_ids = 0;
		nodemap->nmf_allow_root_access = 0;
		nodemap->nmf_block_lookups = 0;

		nodemap->nm_squash_uid = NODEMAP_NOBODY_UID;
		nodemap->nm_squash_gid = NODEMAP_NOBODY_GID;

		lprocfs_nodemap_register(name, is_default, nodemap);

		default_nodemap = nodemap;
	} else {
		nodemap->nm_id = atomic_inc_return(&nodemap_highest_id);
		nodemap->nmf_trust_client_ids =
				default_nodemap->nmf_trust_client_ids;
		nodemap->nmf_allow_root_access =
				default_nodemap->nmf_allow_root_access;
		nodemap->nmf_block_lookups =
				default_nodemap->nmf_block_lookups;

		nodemap->nm_squash_uid = default_nodemap->nm_squash_uid;
		nodemap->nm_squash_gid = default_nodemap->nm_squash_gid;

		lprocfs_nodemap_register(name, is_default, nodemap);
	}

	atomic_set(&nodemap->nm_refcount, 1);
	rc = cfs_hash_add_unique(nodemap_hash, name, &nodemap->nm_hash);

	if (rc == 0)
		goto out;

	CERROR("cannot add nodemap: '%s': rc = %d\n", name, rc);
	nodemap_destroy(nodemap);

out:
	return rc;
}

/**
 * update flag to turn on or off nodemap functions
 * \param	name		nodemap name
 * \param	admin_string	string containing updated value
 * \retval	0 on success
 *
 * Update admin flag to turn on or off nodemap functions.
 */
int nodemap_set_allow_root(const char *name, bool allow_root)
{
	struct lu_nodemap	*nodemap = NULL;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL)
		GOTO(out, rc = -ENOENT);

	nodemap->nmf_allow_root_access = allow_root;
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_set_allow_root);

/**
 * updated trust_client_ids flag for nodemap
 *
 * \param	name		nodemap name
 * \param	trust_string	new value for trust flag
 * \retval	0 on success
 *
 * Update the trust_client_ids flag for a nodemap.
 */
int nodemap_set_trust_client_ids(const char *name, bool trust_client_ids)
{
	struct lu_nodemap	*nodemap = NULL;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL)
		GOTO(out, rc = -ENOENT);

	nodemap->nmf_trust_client_ids = trust_client_ids;
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_set_trust_client_ids);

/**
 * update the squash_uid for a nodemap
 *
 * \param	name		nodemap name
 * \param	uid_string	string containing new squash_uid value
 * \retval	0 on success
 *
 * Update the squash_uid for a nodemap. The squash_uid is the uid
 * that the all client uids are mapped to if nodemap is active,
 * the trust_client_ids flag is not set, and the uid is not in
 * the idmap tree.
 */
int nodemap_set_squash_uid(const char *name, uid_t uid)
{
	struct lu_nodemap	*nodemap = NULL;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL)
		GOTO(out, rc = -ENOENT);

	nodemap->nm_squash_uid = uid;
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_set_squash_uid);

/**
 * update the squash_gid for a nodemap
 *
 * \param	name		nodemap name
 * \param	gid_string	string containing new squash_gid value
 * \retval	0 on success
 *
 * Update the squash_gid for a nodemap. The squash_uid is the gid
 * that the all client gids are mapped to if nodemap is active,
 * the trust_client_ids flag is not set, and the gid is not in
 * the idmap tree.
 */
int nodemap_set_squash_gid(const char *name, gid_t gid)
{
	struct lu_nodemap	*nodemap = NULL;
	int			rc = 0;

	rc = nodemap_lookup(name, &nodemap);
	if (nodemap == NULL)
		GOTO(out, rc = -ENOENT);

	nodemap->nm_squash_gid = gid;
	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_set_squash_gid);

/**
 * Add a nodemap
 *
 * \param	name		name of nodemap
 * \retval	0		success
 * \retval	-EINVAL		invalid nodemap name
 * \retval	-EEXIST		nodemap already exists
 * \retval	-ENOMEM		cannot allocate memory for nodemap
 */
int nodemap_add(const char *name)
{
	return nodemap_create(name, 0);
}
EXPORT_SYMBOL(nodemap_add);

/**
 * Delete a nodemap
 *
 * \param	name		name of nodemmap
 * \retval	0		success
 * \retval	-EINVAL		invalid input
 * \retval	-ENOENT		no existing nodemap
 */
int nodemap_del(const char *name)
{
	struct	lu_nodemap *nodemap;
	int	rc = 0;

	if (strcmp(name, DEFAULT_NODEMAP) == 0)
		GOTO(out, rc = -EINVAL);

	nodemap = cfs_hash_del_key(nodemap_hash, name);
	if (nodemap == NULL)
		GOTO(out, rc = -ENOENT);

	nodemap_putref(nodemap);
out:
	return rc;
}
EXPORT_SYMBOL(nodemap_del);

/**
 * activate nodemap functions
 *
 * \param	value		1 for on, 0 for off
 */
void nodemap_activate(const bool value)
{
	nodemap_active = value;
}
EXPORT_SYMBOL(nodemap_activate);

/**
 * Cleanup nodemap module on exit
 */
static void nodemap_mod_exit(void)
{
	nodemap_cleanup_all();
	lprocfs_remove(&proc_lustre_nodemap_root);
}

/**
 * Initialize the nodemap module
 */
static int __init nodemap_mod_init(void)
{
	int rc = 0;

	rc = nodemap_init_hash();
	if (rc != 0)
		goto cleanup;

	nodemap_procfs_init();
	rc = nodemap_create(DEFAULT_NODEMAP, 1);

cleanup:
	if (rc != 0)
		nodemap_mod_exit();

	return rc;
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Lustre Client Nodemap Management Module");
MODULE_AUTHOR("Joshua Walgenbach <jjw@iu.edu>");

module_init(nodemap_mod_init);
module_exit(nodemap_mod_exit);