/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License 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 for more details. */#include <linux/bpf.h>#include <linux/jhash.h>#include <linux/filter.h>#include <linux/vmalloc.h> struct bpf_htab {	struct bpf_map map;	struct hlist_head *buckets;	spinlock_t lock;	u32 count;	/* number of elements in this hashtable */	u32 n_buckets;	/* number of hash buckets */	u32 elem_size;	/* size of each element in bytes */}; /* each htab element is struct htab_elem + key + value */struct htab_elem {	struct hlist_node hash_node;	struct rcu_head rcu;	u32 hash;	char key[0] __aligned(8);}; /* Called from syscall */static struct bpf_map *htab_map_alloc(union bpf_attr *attr){	struct bpf_htab *htab;	int err, i; 	htab = kzalloc(sizeof(*htab), GFP_USER);	if (!htab)		return ERR_PTR(-ENOMEM); 	/* mandatory map attributes */	htab->map.key_size = attr->key_size;	htab->map.value_size = attr->value_size;	htab->map.max_entries = attr->max_entries; 	/* check sanity of attributes.	 * value_size == 0 may be allowed in the future to use map as a set	 */	err = -EINVAL;	if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||	    htab->map.value_size == 0)		goto free_htab; 	/* hash table size must be power of 2 */	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries); 	err = -E2BIG;	if (htab->map.key_size > MAX_BPF_STACK)		/* eBPF programs initialize keys on stack, so they cannot be		 * larger than max stack size		 */		goto free_htab; 	err = -ENOMEM;	/* prevent zero size kmalloc and check for u32 overflow */	if (htab->n_buckets == 0 ||	    htab->n_buckets > U32_MAX / sizeof(struct hlist_head))		goto free_htab; 	htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct hlist_head),				      GFP_USER | __GFP_NOWARN); 	if (!htab->buckets) {		htab->buckets = vmalloc(htab->n_buckets * sizeof(struct hlist_head));		if (!htab->buckets)			goto free_htab;	} 	for (i = 0; i < htab->n_buckets; i++)		INIT_HLIST_HEAD(&htab->buckets[i]); 	spin_lock_init(&htab->lock);	htab->count = 0; 	htab->elem_size = sizeof(struct htab_elem) +			  round_up(htab->map.key_size, 8) +			  htab->map.value_size;	return &htab->map; free_htab:	kfree(htab);	return ERR_PTR(err);} static inline u32 htab_map_hash(const void *key, u32 key_len){	return jhash(key, key_len, 0);} static inline struct hlist_head *select_bucket(struct bpf_htab *htab, u32 hash){	return &htab->buckets[hash & (htab->n_buckets - 1)];} static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,					 void *key, u32 key_size){	struct htab_elem *l; 	hlist_for_each_entry_rcu(l, head, hash_node)		if (l->hash == hash && !memcmp(&l->key, key, key_size))			return l; 	return NULL;} /* Called from syscall or from eBPF program */static void *htab_map_lookup_elem(struct bpf_map *map, void *key){	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);	struct hlist_head *head;	struct htab_elem *l;	u32 hash, key_size; 	/* Must be called with rcu_read_lock. */	WARN_ON_ONCE(!rcu_read_lock_held()); 	key_size = map->key_size; 	hash = htab_map_hash(key, key_size); 	head = select_bucket(htab, hash); 	l = lookup_elem_raw(head, hash, key, key_size); 	if (l)		return l->key + round_up(map->key_size, 8); 	return NULL;} /* Called from syscall */static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key){	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);	struct hlist_head *head;	struct htab_elem *l, *next_l;	u32 hash, key_size;	int i; 	WARN_ON_ONCE(!rcu_read_lock_held()); 	key_size = map->key_size; 	hash = htab_map_hash(key, key_size); 	head = select_bucket(htab, hash); 	/* lookup the key */	l = lookup_elem_raw(head, hash, key, key_size); 	if (!l) {		i = 0;		goto find_first_elem;	} 	/* key was found, get next key in the same bucket */	next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),				  struct htab_elem, hash_node); 	if (next_l) {		/* if next elem in this hash list is non-zero, just return it */		memcpy(next_key, next_l->key, key_size);		return 0;	} 	/* no more elements in this hash list, go to the next bucket */	i = hash & (htab->n_buckets - 1);	i++; find_first_elem:	/* iterate over buckets */	for (; i < htab->n_buckets; i++) {		head = select_bucket(htab, i); 		/* pick first element in the bucket */		next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),					  struct htab_elem, hash_node);		if (next_l) {			/* if it's not empty, just return it */			memcpy(next_key, next_l->key, key_size);			return 0;		}	} 	/* itereated over all buckets and all elements */	return -ENOENT;} /* Called from syscall or from eBPF program */static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,				u64 map_flags){	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);	struct htab_elem *l_new, *l_old;	struct hlist_head *head;	unsigned long flags;	u32 key_size;	int ret; 	if (map_flags > BPF_EXIST)		/* unknown flags */		return -EINVAL; 	WARN_ON_ONCE(!rcu_read_lock_held()); 	/* allocate new element outside of lock */	l_new = kmalloc(htab->elem_size, GFP_ATOMIC);	if (!l_new)		return -ENOMEM; 	key_size = map->key_size; 	memcpy(l_new->key, key, key_size);	memcpy(l_new->key + round_up(key_size, 8), value, map->value_size); 	l_new->hash = htab_map_hash(l_new->key, key_size); 	/* bpf_map_update_elem() can be called in_irq() */	spin_lock_irqsave(&htab->lock, flags); 	head = select_bucket(htab, l_new->hash); 	l_old = lookup_elem_raw(head, l_new->hash, key, key_size); 	if (!l_old && unlikely(htab->count >= map->max_entries)) {		/* if elem with this 'key' doesn't exist and we've reached		 * max_entries limit, fail insertion of new elem		 */		ret = -E2BIG;		goto err;	} 	if (l_old && map_flags == BPF_NOEXIST) {		/* elem already exists */		ret = -EEXIST;		goto err;	} 	if (!l_old && map_flags == BPF_EXIST) {		/* elem doesn't exist, cannot update it */		ret = -ENOENT;		goto err;	} 	/* add new element to the head of the list, so that concurrent	 * search will find it before old elem	 */	hlist_add_head_rcu(&l_new->hash_node, head);	if (l_old) {		hlist_del_rcu(&l_old->hash_node);		kfree_rcu(l_old, rcu);	} else {		htab->count++;	}	spin_unlock_irqrestore(&htab->lock, flags); 	return 0;err:	spin_unlock_irqrestore(&htab->lock, flags);	kfree(l_new);	return ret;} /* Called from syscall or from eBPF program */static int htab_map_delete_elem(struct bpf_map *map, void *key){	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);	struct hlist_head *head;	struct htab_elem *l;	unsigned long flags;	u32 hash, key_size;	int ret = -ENOENT; 	WARN_ON_ONCE(!rcu_read_lock_held()); 	key_size = map->key_size; 	hash = htab_map_hash(key, key_size); 	spin_lock_irqsave(&htab->lock, flags); 	head = select_bucket(htab, hash); 	l = lookup_elem_raw(head, hash, key, key_size); 	if (l) {		hlist_del_rcu(&l->hash_node);		htab->count--;		kfree_rcu(l, rcu);		ret = 0;	} 	spin_unlock_irqrestore(&htab->lock, flags);	return ret;} static void delete_all_elements(struct bpf_htab *htab){	int i; 	for (i = 0; i < htab->n_buckets; i++) {		struct hlist_head *head = select_bucket(htab, i);		struct hlist_node *n;		struct htab_elem *l; 		hlist_for_each_entry_safe(l, n, head, hash_node) {			hlist_del_rcu(&l->hash_node);			htab->count--;			kfree(l);		}	}} /* Called when map->refcnt goes to zero, either from workqueue or from syscall */static void htab_map_free(struct bpf_map *map){	struct bpf_htab *htab = container_of(map, struct bpf_htab, map); 	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,	 * so the programs (can be more than one that used this map) were	 * disconnected from events. Wait for outstanding critical sections in	 * these programs to complete	 */	synchronize_rcu(); 	/* some of kfree_rcu() callbacks for elements of this map may not have	 * executed. It's ok. Proceed to free residual elements and map itself	 */	delete_all_elements(htab);	kvfree(htab->buckets);	kfree(htab);} static struct bpf_map_ops htab_ops = {	.map_alloc = htab_map_alloc,	.map_free = htab_map_free,	.map_get_next_key = htab_map_get_next_key,	.map_lookup_elem = htab_map_lookup_elem,	.map_update_elem = htab_map_update_elem,	.map_delete_elem = htab_map_delete_elem,}; static struct bpf_map_type_list tl = {	.ops = &htab_ops,	.type = BPF_MAP_TYPE_HASH,}; static int __init register_htab_map(void){	bpf_register_map_type(&tl);	return 0;}late_initcall(register_htab_map);