Commit message: bpf: Fix integer overflow involving bucket_size

In __htab_map_lookup_and_delete_batch(), hash buckets are iterated
over to count the number of elements in each bucket (bucket_size).
If bucket_size is large enough, the multiplication to calculate
kvmalloc() size could overflow, resulting in out-of-bounds write
as reported by KASAN:

  [...]
  [  104.986052] BUG: KASAN: vmalloc-out-of-bounds in __htab_map_lookup_and_delete_batch+0x5ce/0xb60
  [  104.986489] Write of size 4194224 at addr ffffc9010503be70 by task crash/112
  [  104.986889]
  [  104.987193] CPU: 0 PID: 112 Comm: crash Not tainted 5.14.0-rc4 #13
  [  104.987552] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
  [  104.988104] Call Trace:
  [  104.988410]  dump_stack_lvl+0x34/0x44
  [  104.988706]  print_address_description.constprop.0+0x21/0x140
  [  104.988991]  ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
  [  104.989327]  ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
  [  104.989622]  kasan_report.cold+0x7f/0x11b
  [  104.989881]  ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
  [  104.990239]  kasan_check_range+0x17c/0x1e0
  [  104.990467]  memcpy+0x39/0x60
  [  104.990670]  __htab_map_lookup_and_delete_batch+0x5ce/0xb60
  [  104.990982]  ? __wake_up_common+0x4d/0x230
  [  104.991256]  ? htab_of_map_free+0x130/0x130
  [  104.991541]  bpf_map_do_batch+0x1fb/0x220
  [...]

In hashtable, if the elements' keys have the same jhash() value, the
elements will be put into the same bucket. By putting a lot of elements
into a single bucket, the value of bucket_size can be increased to
trigger the integer overflow.

Triggering the overflow is possible for both callers with CAP_SYS_ADMIN
and callers without CAP_SYS_ADMIN.

It will be trivial for a caller with CAP_SYS_ADMIN to intentionally
reach this overflow by enabling BPF_F_ZERO_SEED. As this flag will set
the random seed passed to jhash() to 0, it will be easy for the caller
to prepare keys which will be hashed into the same value, and thus put
all the elements into the same bucket.

If the caller does not have CAP_SYS_ADMIN, BPF_F_ZERO_SEED cannot be
used. However, it will be still technically possible to trigger the
overflow, by guessing the random seed value passed to jhash() (32bit)
and repeating the attempt to trigger the overflow. In this case,
the probability to trigger the overflow will be low and will take
a very long time.

Fix the integer overflow by calling kvmalloc_array() instead of
kvmalloc() to allocate memory.

Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map")
Signed-off-by: Tatsuhiko Yasumatsu <th.yasumatsu@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210806150419.109658-1-th.yasumatsu@gmail.com
CVE: CVE-2021-38166
CWE: CWE-787
Vulnerability description: In kernel/bpf/hashtab.c in the Linux kernel through 5.13.8, there is an integer overflow and out-of-bounds write when many elements are placed in a single bucket. NOTE: exploitation might be impractical without the CAP_SYS_ADMIN capability.

Project: bpf
File: hashtab.c

static int htab_of_map_gen_lookup(struct bpf_map *map,
				  struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 2);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);

	return insn - insn_buf;
}

Project: bpf
File: hashtab.c

static int __bpf_hash_map_seq_show(struct seq_file *seq, struct htab_elem *elem)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;
	u32 roundup_key_size, roundup_value_size;
	struct bpf_iter__bpf_map_elem ctx = {};
	struct bpf_map *map = info->map;
	struct bpf_iter_meta meta;
	int ret = 0, off = 0, cpu;
	struct bpf_prog *prog;
	void __percpu *pptr;

	meta.seq = seq;
	prog = bpf_iter_get_info(&meta, elem == NULL);
	if (prog) {
		ctx.meta = &meta;
		ctx.map = info->map;
		if (elem) {
			roundup_key_size = round_up(map->key_size, 8);
			ctx.key = elem->key;
			if (!info->percpu_value_buf) {
				ctx.value = elem->key + roundup_key_size;
			} else {
				roundup_value_size = round_up(map->value_size, 8);
				pptr = htab_elem_get_ptr(elem, map->key_size);
				for_each_possible_cpu(cpu) {
					bpf_long_memcpy(info->percpu_value_buf + off,
							per_cpu_ptr(pptr, cpu),
							roundup_value_size);
					off += roundup_value_size;
				}
				ctx.value = info->percpu_value_buf;
			}
		}
		ret = bpf_iter_run_prog(prog, &ctx);
	}

	return ret;
}

Project: bpf
File: hashtab.c

static void htab_map_free(struct bpf_map *map)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	int i;

	/* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback.
	 * bpf_free_used_maps() is called after bpf prog is no longer executing.
	 * There is no need to synchronize_rcu() here to protect map elements.
	 */

	/* some of free_htab_elem() callbacks for elements of this map may
	 * not have executed. Wait for them.
	 */
	rcu_barrier();
	if (!htab_is_prealloc(htab))
		delete_all_elements(htab);
	else
		prealloc_destroy(htab);

	free_percpu(htab->extra_elems);
	bpf_map_area_free(htab->buckets);
	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
		free_percpu(htab->map_locked[i]);
	lockdep_unregister_key(&htab->lockdep_key);
	kfree(htab);
}

Project: bpf
File: hashtab.c

int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
				void *key, void *value, u64 map_flags)
{
	void *ptr;
	int ret;
	u32 ufd = *(u32 *)value;

	ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
	if (IS_ERR(ptr))
		return PTR_ERR(ptr);

	ret = htab_map_update_elem(map, key, &ptr, map_flags);
	if (ret)
		map->ops->map_fd_put_ptr(ptr);

	return ret;
}

Project: bpf
File: hashtab.c

htab_lru_map_lookup_and_delete_batch(struct bpf_map *map,
				     const union bpf_attr *attr,
				     union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  true, false);
}

Project: bpf
File: hashtab.c

static int bpf_iter_init_hash_map(void *priv_data,
				  struct bpf_iter_aux_info *aux)
{
	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;
	struct bpf_map *map = aux->map;
	void *value_buf;
	u32 buf_size;

	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH) {
		buf_size = round_up(map->value_size, 8) * num_possible_cpus();
		value_buf = kmalloc(buf_size, GFP_USER | __GFP_NOWARN);
		if (!value_buf)
			return -ENOMEM;

		seq_info->percpu_value_buf = value_buf;
	}

	seq_info->map = map;
	seq_info->htab = container_of(map, struct bpf_htab, map);
	return 0;
}

Project: bpf
File: hashtab.c

static void *bpf_hash_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;

	++*pos;
	++info->skip_elems;
	return bpf_hash_map_seq_find_next(info, v);
}

Project: bpf
File: hashtab.c

static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l)
		return l->key + round_up(map->key_size, 8);

	return NULL;
}

Project: bpf
File: hashtab.c

static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &htab->buckets[hash & (htab->n_buckets - 1)];
}

Project: bpf
File: hashtab.c

static __always_inline void *__htab_lru_map_lookup_elem(struct bpf_map *map,
							void *key, const bool mark)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l) {
		if (mark)
			bpf_lru_node_set_ref(&l->lru_node);
		return l->key + round_up(map->key_size, 8);
	}

	return NULL;
}

Project: bpf
File: hashtab.c

static inline u32 htab_map_hash(const void *key, u32 key_len, u32 hashrnd)
{
	return jhash(key, key_len, hashrnd);
}

Project: bpf
File: hashtab.c

static void *htab_percpu_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l)
		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
	else
		return NULL;
}

Project: bpf
File: hashtab.c

static struct htab_elem *lookup_elem_raw(struct hlist_nulls_head *head, u32 hash,
					 void *key, u32 key_size)
{
	struct hlist_nulls_node *n;
	struct htab_elem *l;

	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l->hash == hash && !memcmp(&l->key, key, key_size))
			return l;

	return NULL;
}

Project: bpf
File: hashtab.c

htab_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
					const union bpf_attr *attr,
					union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  false, true);
}

Project: bpf
File: hashtab.c

static int __htab_percpu_map_update_elem(struct bpf_map *map, void *key,
					 void *value, u64 map_flags,
					 bool onallcpus)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (l_old) {
		/* per-cpu hash map can update value in-place */
		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
				value, onallcpus);
	} else {
		l_new = alloc_htab_elem(htab, key, value, key_size,
					hash, true, onallcpus, NULL);
		if (IS_ERR(l_new)) {
			ret = PTR_ERR(l_new);
			goto err;
		}
		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

Project: bpf
File: hashtab.c

static int htab_percpu_map_update_elem(struct bpf_map *map, void *key,
				       void *value, u64 map_flags)
{
	return __htab_percpu_map_update_elem(map, key, value, map_flags, false);
}

Project: bpf
File: hashtab.c

static void pcpu_init_value(struct bpf_htab *htab, void __percpu *pptr,
			    void *value, bool onallcpus)
{
	/* When using prealloc and not setting the initial value on all cpus,
	 * zero-fill element values for other cpus (just as what happens when
	 * not using prealloc). Otherwise, bpf program has no way to ensure
	 * known initial values for cpus other than current one
	 * (onallcpus=false always when coming from bpf prog).
	 */
	if (htab_is_prealloc(htab) && !onallcpus) {
		u32 size = round_up(htab->map.value_size, 8);
		int current_cpu = raw_smp_processor_id();
		int cpu;

		for_each_possible_cpu(cpu) {
			if (cpu == current_cpu)
				bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value,
						size);
			else
				memset(per_cpu_ptr(pptr, cpu), 0, size);
		}
	} else {
		pcpu_copy_value(htab, pptr, value, onallcpus);
	}
}

Project: bpf
File: hashtab.c

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_nulls_head *head;
	struct bucket *b;
	struct htab_elem *l;
	unsigned long flags;
	u32 hash, key_size;
	int ret;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);
	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l) {
		hlist_nulls_del_rcu(&l->hash_node);
		free_htab_elem(htab, l);
	} else {
		ret = -ENOENT;
	}

	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

Project: bpf
File: hashtab.c

static int __htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
					     void *value, bool is_lru_map,
					     bool is_percpu, u64 flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	unsigned long bflags;
	struct htab_elem *l;
	u32 hash, key_size;
	struct bucket *b;
	int ret;

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);
	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &bflags);
	if (ret)
		return ret;

	l = lookup_elem_raw(head, hash, key, key_size);
	if (!l) {
		ret = -ENOENT;
	} else {
		if (is_percpu) {
			u32 roundup_value_size = round_up(map->value_size, 8);
			void __percpu *pptr;
			int off = 0, cpu;

			pptr = htab_elem_get_ptr(l, key_size);
			for_each_possible_cpu(cpu) {
				bpf_long_memcpy(value + off,
						per_cpu_ptr(pptr, cpu),
						roundup_value_size);
				off += roundup_value_size;
			}
		} else {
			u32 roundup_key_size = round_up(map->key_size, 8);

			if (flags & BPF_F_LOCK)
				copy_map_value_locked(map, value, l->key +
						      roundup_key_size,
						      true);
			else
				copy_map_value(map, value, l->key +
					       roundup_key_size);
			check_and_init_map_lock(map, value);
		}

		hlist_nulls_del_rcu(&l->hash_node);
		if (!is_lru_map)
			free_htab_elem(htab, l);
	}

	htab_unlock_bucket(htab, b, hash, bflags);

	if (is_lru_map && l)
		bpf_lru_push_free(&htab->lru, &l->lru_node);

	return ret;
}

Project: bpf
File: hashtab.c

static void htab_elem_free_rcu(struct rcu_head *head)
{
	struct htab_elem *l = container_of(head, struct htab_elem, rcu);
	struct bpf_htab *htab = l->htab;

	htab_elem_free(htab, l);
}

Project: bpf
File: hashtab.c

static struct bpf_map *htab_of_map_alloc(union bpf_attr *attr)
{
	struct bpf_map *map, *inner_map_meta;

	inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
	if (IS_ERR(inner_map_meta))
		return inner_map_meta;

	map = htab_map_alloc(attr);
	if (IS_ERR(map)) {
		bpf_map_meta_free(inner_map_meta);
		return map;
	}

	map->inner_map_meta = inner_map_meta;

	return map;
}

Project: bpf
File: hashtab.c

static int htab_lru_map_delete_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct bucket *b;
	struct htab_elem *l;
	unsigned long flags;
	u32 hash, key_size;
	int ret;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);
	b = __select_bucket(htab, hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l)
		hlist_nulls_del_rcu(&l->hash_node);
	else
		ret = -ENOENT;

	htab_unlock_bucket(htab, b, hash, flags);
	if (l)
		bpf_lru_push_free(&htab->lru, &l->lru_node);
	return ret;
}

Project: bpf
File: hashtab.c

static void *bpf_hash_map_seq_start(struct seq_file *seq, loff_t *pos)
{
	struct bpf_iter_seq_hash_map_info *info = seq->private;
	struct htab_elem *elem;

	elem = bpf_hash_map_seq_find_next(info, NULL);
	if (!elem)
		return NULL;

	if (*pos == 0)
		++*pos;
	return elem;
}

Project: bpf
File: hashtab.c

static inline int htab_lock_bucket(const struct bpf_htab *htab,
				   struct bucket *b, u32 hash,
				   unsigned long *pflags)
{
	unsigned long flags;

	hash = hash & HASHTAB_MAP_LOCK_MASK;

	migrate_disable();
	if (unlikely(__this_cpu_inc_return(*(htab->map_locked[hash])) != 1)) {
		__this_cpu_dec(*(htab->map_locked[hash]));
		migrate_enable();
		return -EBUSY;
	}

	if (htab_use_raw_lock(htab))
		raw_spin_lock_irqsave(&b->raw_lock, flags);
	else
		spin_lock_irqsave(&b->lock, flags);
	*pflags = flags;

	return 0;
}

Project: bpf
File: hashtab.c

static inline bool htab_use_raw_lock(const struct bpf_htab *htab)
{
	return (!IS_ENABLED(CONFIG_PREEMPT_RT) || htab_is_prealloc(htab));
}

Project: bpf
File: hashtab.c

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_nulls_head *head;
	struct htab_elem *l;
	u32 hash, key_size;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	head = select_bucket(htab, hash);

	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);

	return l;
}

Project: bpf
File: hashtab.c

static int prealloc_init(struct bpf_htab *htab)
{
	u32 num_entries = htab->map.max_entries;
	int err = -ENOMEM, i;

	if (!htab_is_percpu(htab) && !htab_is_lru(htab))
		num_entries += num_possible_cpus();

	htab->elems = bpf_map_area_alloc((u64)htab->elem_size * num_entries,
					 htab->map.numa_node);
	if (!htab->elems)
		return -ENOMEM;

	if (!htab_is_percpu(htab))
		goto skip_percpu_elems;

	for (i = 0; i < num_entries; i++) {
		u32 size = round_up(htab->map.value_size, 8);
		void __percpu *pptr;

		pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
					    GFP_USER | __GFP_NOWARN);
		if (!pptr)
			goto free_elems;
		htab_elem_set_ptr(get_htab_elem(htab, i), htab->map.key_size,
				  pptr);
		cond_resched();
	}

skip_percpu_elems:
	if (htab_is_lru(htab))
		err = bpf_lru_init(&htab->lru,
				   htab->map.map_flags & BPF_F_NO_COMMON_LRU,
				   offsetof(struct htab_elem, hash) -
				   offsetof(struct htab_elem, lru_node),
				   htab_lru_map_delete_node,
				   htab);
	else
		err = pcpu_freelist_init(&htab->freelist);

	if (err)
		goto free_elems;

	if (htab_is_lru(htab))
		bpf_lru_populate(&htab->lru, htab->elems,
				 offsetof(struct htab_elem, lru_node),
				 htab->elem_size, num_entries);
	else
		pcpu_freelist_populate(&htab->freelist,
				       htab->elems + offsetof(struct htab_elem, fnode),
				       htab->elem_size, num_entries);

	return 0;

free_elems:
	htab_free_elems(htab);
	return err;
}

Project: bpf
File: hashtab.c

static int htab_lru_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 = NULL;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	/* For LRU, we need to alloc before taking bucket's
	 * spinlock because getting free nodes from LRU may need
	 * to remove older elements from htab and this removal
	 * operation will need a bucket lock.
	 */
	l_new = prealloc_lru_pop(htab, key, hash);
	if (!l_new)
		return -ENOMEM;
	memcpy(l_new->key + round_up(map->key_size, 8), value, map->value_size);

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	/* add new element to the head of the list, so that
	 * concurrent search will find it before old elem
	 */
	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	if (l_old) {
		bpf_lru_node_set_ref(&l_new->lru_node);
		hlist_nulls_del_rcu(&l_old->hash_node);
	}
	ret = 0;

err:
	htab_unlock_bucket(htab, b, hash, flags);

	if (ret)
		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
	else if (l_old)
		bpf_lru_push_free(&htab->lru, &l_old->lru_node);

	return ret;
}

Project: bpf
File: hashtab.c

static void delete_all_elements(struct bpf_htab *htab)
{
	int i;

	for (i = 0; i < htab->n_buckets; i++) {
		struct hlist_nulls_head *head = select_bucket(htab, i);
		struct hlist_nulls_node *n;
		struct htab_elem *l;

		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
			hlist_nulls_del_rcu(&l->hash_node);
			htab_elem_free(htab, l);
		}
	}
}

Project: bpf
File: hashtab.c

static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
		       u64 map_flags)
{
	if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
		/* elem already exists */
		return -EEXIST;

	if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
		/* elem doesn't exist, cannot update it */
		return -ENOENT;

	return 0;
}

Project: bpf
File: hashtab.c

static bool htab_lru_map_delete_node(void *arg, struct bpf_lru_node *node)
{
	struct bpf_htab *htab = (struct bpf_htab *)arg;
	struct htab_elem *l = NULL, *tgt_l;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	unsigned long flags;
	struct bucket *b;
	int ret;

	tgt_l = container_of(node, struct htab_elem, lru_node);
	b = __select_bucket(htab, tgt_l->hash);
	head = &b->head;

	ret = htab_lock_bucket(htab, b, tgt_l->hash, &flags);
	if (ret)
		return false;

	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l == tgt_l) {
			hlist_nulls_del_rcu(&l->hash_node);
			break;
		}

	htab_unlock_bucket(htab, b, tgt_l->hash, flags);

	return l == tgt_l;
}

Project: bpf
File: hashtab.c

static void htab_init_buckets(struct bpf_htab *htab)
{
	unsigned i;

	for (i = 0; i < htab->n_buckets; i++) {
		INIT_HLIST_NULLS_HEAD(&htab->buckets[i].head, i);
		if (htab_use_raw_lock(htab)) {
			raw_spin_lock_init(&htab->buckets[i].raw_lock);
			lockdep_set_class(&htab->buckets[i].raw_lock,
					  &htab->lockdep_key);
		} else {
			spin_lock_init(&htab->buckets[i].lock);
			lockdep_set_class(&htab->buckets[i].lock,
					  &htab->lockdep_key);
		}
		cond_resched();
	}
}

Project: bpf
File: hashtab.c

static void pcpu_copy_value(struct bpf_htab *htab, void __percpu *pptr,
			    void *value, bool onallcpus)
{
	if (!onallcpus) {
		/* copy true value_size bytes */
		memcpy(this_cpu_ptr(pptr), value, htab->map.value_size);
	} else {
		u32 size = round_up(htab->map.value_size, 8);
		int off = 0, cpu;

		for_each_possible_cpu(cpu) {
			bpf_long_memcpy(per_cpu_ptr(pptr, cpu),
					value + off, size);
			off += size;
		}
	}
}

Project: bpf
File: hashtab.c

static inline bool htab_is_prealloc(const struct bpf_htab *htab)
{
	return !(htab->map.map_flags & BPF_F_NO_PREALLOC);
}

Project: bpf
File: hashtab.c

int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value)
{
	struct htab_elem *l;
	void __percpu *pptr;
	int ret = -ENOENT;
	int cpu, off = 0;
	u32 size;

	/* per_cpu areas are zero-filled and bpf programs can only
	 * access 'value_size' of them, so copying rounded areas
	 * will not leak any kernel data
	 */
	size = round_up(map->value_size, 8);
	rcu_read_lock();
	l = __htab_map_lookup_elem(map, key);
	if (!l)
		goto out;
	/* We do not mark LRU map element here in order to not mess up
	 * eviction heuristics when user space does a map walk.
	 */
	pptr = htab_elem_get_ptr(l, map->key_size);
	for_each_possible_cpu(cpu) {
		bpf_long_memcpy(value + off,
				per_cpu_ptr(pptr, cpu), size);
		off += size;
	}
	ret = 0;
out:
	rcu_read_unlock();
	return ret;
}

Project: bpf
File: hashtab.c

static int htab_map_alloc_check(union bpf_attr *attr)
{
	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	/* percpu_lru means each cpu has its own LRU list.
	 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
	 * the map's value itself is percpu.  percpu_lru has
	 * nothing to do with the map's value.
	 */
	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
	bool zero_seed = (attr->map_flags & BPF_F_ZERO_SEED);
	int numa_node = bpf_map_attr_numa_node(attr);

	BUILD_BUG_ON(offsetof(struct htab_elem, htab) !=
		     offsetof(struct htab_elem, hash_node.pprev));
	BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) !=
		     offsetof(struct htab_elem, hash_node.pprev));

	if (lru && !bpf_capable())
		/* LRU implementation is much complicated than other
		 * maps.  Hence, limit to CAP_BPF.
		 */
		return -EPERM;

	if (zero_seed && !capable(CAP_SYS_ADMIN))
		/* Guard against local DoS, and discourage production use. */
		return -EPERM;

	if (attr->map_flags & ~HTAB_CREATE_FLAG_MASK ||
	    !bpf_map_flags_access_ok(attr->map_flags))
		return -EINVAL;

	if (!lru && percpu_lru)
		return -EINVAL;

	if (lru && !prealloc)
		return -ENOTSUPP;

	if (numa_node != NUMA_NO_NODE && (percpu || percpu_lru))
		return -EINVAL;

	/* check sanity of attributes.
	 * value_size == 0 may be allowed in the future to use map as a set
	 */
	if (attr->max_entries == 0 || attr->key_size == 0 ||
	    attr->value_size == 0)
		return -EINVAL;

	if ((u64)attr->key_size + attr->value_size >= KMALLOC_MAX_SIZE -
	   sizeof(struct htab_elem))
		/* if key_size + value_size is bigger, the user space won't be
		 * able to access the elements via bpf syscall. This check
		 * also makes sure that the elem_size doesn't overflow and it's
		 * kmalloc-able later in htab_map_update_elem()
		 */
		return -E2BIG;

	return 0;
}

Project: bpf
File: hashtab.c

static void *htab_of_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_map **inner_map  = htab_map_lookup_elem(map, key);

	if (!inner_map)
		return NULL;

	return READ_ONCE(*inner_map);
}

Project: bpf
File: hashtab.c

static int htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
					   void *value, u64 map_flags)
{
	return __htab_lru_percpu_map_update_elem(map, key, value, map_flags,
						 false);
}

Project: bpf
File: hashtab.c

static int bpf_for_each_hash_elem(struct bpf_map *map, void *callback_fn,
				  void *callback_ctx, u64 flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	struct htab_elem *elem;
	u32 roundup_key_size;
	int i, num_elems = 0;
	void __percpu *pptr;
	struct bucket *b;
	void *key, *val;
	bool is_percpu;
	u64 ret = 0;

	if (flags != 0)
		return -EINVAL;

	is_percpu = htab_is_percpu(htab);

	roundup_key_size = round_up(map->key_size, 8);
	/* disable migration so percpu value prepared here will be the
	 * same as the one seen by the bpf program with bpf_map_lookup_elem().
	 */
	if (is_percpu)
		migrate_disable();
	for (i = 0; i < htab->n_buckets; i++) {
		b = &htab->buckets[i];
		rcu_read_lock();
		head = &b->head;
		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
			key = elem->key;
			if (is_percpu) {
				/* current cpu value for percpu map */
				pptr = htab_elem_get_ptr(elem, map->key_size);
				val = this_cpu_ptr(pptr);
			} else {
				val = elem->key + roundup_key_size;
			}
			num_elems++;
			ret = BPF_CAST_CALL(callback_fn)((u64)(long)map,
					(u64)(long)key, (u64)(long)val,
					(u64)(long)callback_ctx, 0);
			/* return value: 0 - continue, 1 - stop and return */
			if (ret) {
				rcu_read_unlock();
				goto out;
			}
		}
		rcu_read_unlock();
	}
out:
	if (is_percpu)
		migrate_enable();
	return num_elems;
}

Project: bpf
File: hashtab.c

int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
			   u64 map_flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	int ret;

	rcu_read_lock();
	if (htab_is_lru(htab))
		ret = __htab_lru_percpu_map_update_elem(map, key, value,
							map_flags, true);
	else
		ret = __htab_percpu_map_update_elem(map, key, value, map_flags,
						    true);
	rcu_read_unlock();

	return ret;
}

Project: bpf
File: hashtab.c

static bool htab_is_percpu(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
}

Project: bpf
File: hashtab.c

htab_map_lookup_and_delete_batch(struct bpf_map *map,
				 const union bpf_attr *attr,
				 union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  false, false);
}

Project: bpf
File: hashtab.c

bpf_hash_map_seq_find_next(struct bpf_iter_seq_hash_map_info *info,
			   struct htab_elem *prev_elem)
{
	const struct bpf_htab *htab = info->htab;
	u32 skip_elems = info->skip_elems;
	u32 bucket_id = info->bucket_id;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	struct htab_elem *elem;
	struct bucket *b;
	u32 i, count;

	if (bucket_id >= htab->n_buckets)
		return NULL;

	/* try to find next elem in the same bucket */
	if (prev_elem) {
		/* no update/deletion on this bucket, prev_elem should be still valid
		 * and we won't skip elements.
		 */
		n = rcu_dereference_raw(hlist_nulls_next_rcu(&prev_elem->hash_node));
		elem = hlist_nulls_entry_safe(n, struct htab_elem, hash_node);
		if (elem)
			return elem;

		/* not found, unlock and go to the next bucket */
		b = &htab->buckets[bucket_id++];
		rcu_read_unlock();
		skip_elems = 0;
	}

	for (i = bucket_id; i < htab->n_buckets; i++) {
		b = &htab->buckets[i];
		rcu_read_lock();

		count = 0;
		head = &b->head;
		hlist_nulls_for_each_entry_rcu(elem, n, head, hash_node) {
			if (count >= skip_elems) {
				info->bucket_id = i;
				info->skip_elems = count;
				return elem;
			}
			count++;
		}

		rcu_read_unlock();
		skip_elems = 0;
	}

	info->bucket_id = i;
	info->skip_elems = 0;
	return NULL;
}

Project: bpf
File: hashtab.c

int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
{
	void **ptr;
	int ret = 0;

	if (!map->ops->map_fd_sys_lookup_elem)
		return -ENOTSUPP;

	rcu_read_lock();
	ptr = htab_map_lookup_elem(map, key);
	if (ptr)
		*value = map->ops->map_fd_sys_lookup_elem(READ_ONCE(*ptr));
	else
		ret = -ENOENT;
	rcu_read_unlock();

	return ret;
}

Project: bpf
File: hashtab.c

static void htab_elem_free(struct bpf_htab *htab, struct htab_elem *l)
{
	if (htab->map.map_type == BPF_MAP_TYPE_PERCPU_HASH)
		free_percpu(htab_elem_get_ptr(l, htab->map.key_size));
	kfree(l);
}

Project: bpf
File: hashtab.c

static int bpf_hash_map_seq_show(struct seq_file *seq, void *v)
{
	return __bpf_hash_map_seq_show(seq, v);
}

Project: bpf
File: hashtab.c

static inline void __percpu *htab_elem_get_ptr(struct htab_elem *l, u32 key_size)
{
	return *(void __percpu **)(l->key + key_size);
}

Project: bpf
File: hashtab.c

static void *htab_lru_percpu_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct htab_elem *l = __htab_map_lookup_elem(map, key);

	if (l) {
		bpf_lru_node_set_ref(&l->lru_node);
		return this_cpu_ptr(htab_elem_get_ptr(l, map->key_size));
	}

	return NULL;
}

Project: bpf
File: hashtab.c

static int htab_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
					   void *value, u64 flags)
{
	return __htab_map_lookup_and_delete_elem(map, key, value, false, false,
						 flags);
}

Project: bpf
File: hashtab.c

static void bpf_iter_fini_hash_map(void *priv_data)
{
	struct bpf_iter_seq_hash_map_info *seq_info = priv_data;

	kfree(seq_info->percpu_value_buf);
}

Project: bpf
File: hashtab.c

static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
{
	bool percpu = (attr->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
		       attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	bool lru = (attr->map_type == BPF_MAP_TYPE_LRU_HASH ||
		    attr->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH);
	/* percpu_lru means each cpu has its own LRU list.
	 * it is different from BPF_MAP_TYPE_PERCPU_HASH where
	 * the map's value itself is percpu.  percpu_lru has
	 * nothing to do with the map's value.
	 */
	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
	struct bpf_htab *htab;
	int err, i;

	htab = kzalloc(sizeof(*htab), GFP_USER | __GFP_ACCOUNT);
	if (!htab)
		return ERR_PTR(-ENOMEM);

	lockdep_register_key(&htab->lockdep_key);

	bpf_map_init_from_attr(&htab->map, attr);

	if (percpu_lru) {
		/* ensure each CPU's lru list has >=1 elements.
		 * since we are at it, make each lru list has the same
		 * number of elements.
		 */
		htab->map.max_entries = roundup(attr->max_entries,
						num_possible_cpus());
		if (htab->map.max_entries < attr->max_entries)
			htab->map.max_entries = rounddown(attr->max_entries,
							  num_possible_cpus());
	}

	/* hash table size must be power of 2 */
	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);

	htab->elem_size = sizeof(struct htab_elem) +
			  round_up(htab->map.key_size, 8);
	if (percpu)
		htab->elem_size += sizeof(void *);
	else
		htab->elem_size += round_up(htab->map.value_size, 8);

	err = -E2BIG;
	/* prevent zero size kmalloc and check for u32 overflow */
	if (htab->n_buckets == 0 ||
	    htab->n_buckets > U32_MAX / sizeof(struct bucket))
		goto free_htab;

	err = -ENOMEM;
	htab->buckets = bpf_map_area_alloc(htab->n_buckets *
					   sizeof(struct bucket),
					   htab->map.numa_node);
	if (!htab->buckets)
		goto free_htab;

	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++) {
		htab->map_locked[i] = bpf_map_alloc_percpu(&htab->map,
							   sizeof(int),
							   sizeof(int),
							   GFP_USER);
		if (!htab->map_locked[i])
			goto free_map_locked;
	}

	if (htab->map.map_flags & BPF_F_ZERO_SEED)
		htab->hashrnd = 0;
	else
		htab->hashrnd = get_random_int();

	htab_init_buckets(htab);

	if (prealloc) {
		err = prealloc_init(htab);
		if (err)
			goto free_map_locked;

		if (!percpu && !lru) {
			/* lru itself can remove the least used element, so
			 * there is no need for an extra elem during map_update.
			 */
			err = alloc_extra_elems(htab);
			if (err)
				goto free_prealloc;
		}
	}

	return &htab->map;

free_prealloc:
	prealloc_destroy(htab);
free_map_locked:
	for (i = 0; i < HASHTAB_MAP_LOCK_COUNT; i++)
		free_percpu(htab->map_locked[i]);
	bpf_map_area_free(htab->buckets);
free_htab:
	lockdep_unregister_key(&htab->lockdep_key);
	kfree(htab);
	return ERR_PTR(err);
}

Project: bpf
File: hashtab.c

static void htab_put_fd_value(struct bpf_htab *htab, struct htab_elem *l)
{
	struct bpf_map *map = &htab->map;
	void *ptr;

	if (map->ops->map_fd_put_ptr) {
		ptr = fd_htab_map_get_ptr(map, l);
		map->ops->map_fd_put_ptr(ptr);
	}
}

Project: bpf
File: hashtab.c

static void *fd_htab_map_get_ptr(const struct bpf_map *map, struct htab_elem *l)
{
	return *(void **)(l->key + roundup(map->key_size, 8));
}

Project: bpf
File: hashtab.c

static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
	       BITS_PER_LONG == 64;
}

Project: bpf
File: hashtab.c

static int alloc_extra_elems(struct bpf_htab *htab)
{
	struct htab_elem *__percpu *pptr, *l_new;
	struct pcpu_freelist_node *l;
	int cpu;

	pptr = bpf_map_alloc_percpu(&htab->map, sizeof(struct htab_elem *), 8,
				    GFP_USER | __GFP_NOWARN);
	if (!pptr)
		return -ENOMEM;

	for_each_possible_cpu(cpu) {
		l = pcpu_freelist_pop(&htab->freelist);
		/* pop will succeed, since prealloc_init()
		 * preallocated extra num_possible_cpus elements
		 */
		l_new = container_of(l, struct htab_elem, fnode);
		*per_cpu_ptr(pptr, cpu) = l_new;
	}
	htab->extra_elems = pptr;
	return 0;
}

Project: bpf
File: hashtab.c

static void free_htab_elem(struct bpf_htab *htab, struct htab_elem *l)
{
	htab_put_fd_value(htab, l);

	if (htab_is_prealloc(htab)) {
		__pcpu_freelist_push(&htab->freelist, &l->fnode);
	} else {
		atomic_dec(&htab->count);
		l->htab = htab;
		call_rcu(&l->rcu, htab_elem_free_rcu);
	}
}

Project: bpf
File: hashtab.c

static int htab_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	return insn - insn_buf;
}

Project: bpf
File: hashtab.c

static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
				   struct seq_file *m)
{
	void *value;

	rcu_read_lock();

	value = htab_map_lookup_elem(map, key);
	if (!value) {
		rcu_read_unlock();
		return;
	}

	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
	seq_puts(m, ": ");
	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
	seq_puts(m, "\n");

	rcu_read_unlock();
}

Project: bpf
File: hashtab.c

htab_lru_percpu_map_lookup_batch(struct bpf_map *map,
				 const union bpf_attr *attr,
				 union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  true, true);
}

Project: bpf
File: hashtab.c

static int htab_lru_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
						      void *key, void *value,
						      u64 flags)
{
	return __htab_map_lookup_and_delete_elem(map, key, value, true, true,
						 flags);
}

Project: bpf
File: hashtab.c

htab_lru_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
			  union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  true, false);
}

Project: bpf
File: hashtab.c

static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
					  struct seq_file *m)
{
	struct htab_elem *l;
	void __percpu *pptr;
	int cpu;

	rcu_read_lock();

	l = __htab_map_lookup_elem(map, key);
	if (!l) {
		rcu_read_unlock();
		return;
	}

	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
	seq_puts(m, ": {\n");
	pptr = htab_elem_get_ptr(l, map->key_size);
	for_each_possible_cpu(cpu) {
		seq_printf(m, "\tcpu%d: ", cpu);
		btf_type_seq_show(map->btf, map->btf_value_type_id,
				  per_cpu_ptr(pptr, cpu), m);
		seq_puts(m, "\n");
	}
	seq_puts(m, "}\n");

	rcu_read_unlock();
}

Project: bpf
File: hashtab.c

htab_lru_percpu_map_lookup_and_delete_batch(struct bpf_map *map,
					    const union bpf_attr *attr,
					    union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, true,
						  true, true);
}

Project: bpf
File: hashtab.c

static void bpf_hash_map_seq_stop(struct seq_file *seq, void *v)
{
	if (!v)
		(void)__bpf_hash_map_seq_show(seq, NULL);
	else
		rcu_read_unlock();
}

Project: bpf
File: hashtab.c

static int htab_percpu_map_lookup_and_delete_elem(struct bpf_map *map,
						  void *key, void *value,
						  u64 flags)
{
	return __htab_map_lookup_and_delete_elem(map, key, value, false, true,
						 flags);
}

Project: bpf
File: hashtab.c

__htab_map_lookup_and_delete_batch(struct bpf_map *map,
				   const union bpf_attr *attr,
				   union bpf_attr __user *uattr,
				   bool do_delete, bool is_lru_map,
				   bool is_percpu)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	u32 bucket_cnt, total, key_size, value_size, roundup_key_size;
	void *keys = NULL, *values = NULL, *value, *dst_key, *dst_val;
	void __user *uvalues = u64_to_user_ptr(attr->batch.values);
	void __user *ukeys = u64_to_user_ptr(attr->batch.keys);
	void __user *ubatch = u64_to_user_ptr(attr->batch.in_batch);
	u32 batch, max_count, size, bucket_size;
	struct htab_elem *node_to_free = NULL;
	u64 elem_map_flags, map_flags;
	struct hlist_nulls_head *head;
	struct hlist_nulls_node *n;
	unsigned long flags = 0;
	bool locked = false;
	struct htab_elem *l;
	struct bucket *b;
	int ret = 0;

	elem_map_flags = attr->batch.elem_flags;
	if ((elem_map_flags & ~BPF_F_LOCK) ||
	    ((elem_map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map)))
		return -EINVAL;

	map_flags = attr->batch.flags;
	if (map_flags)
		return -EINVAL;

	max_count = attr->batch.count;
	if (!max_count)
		return 0;

	if (put_user(0, &uattr->batch.count))
		return -EFAULT;

	batch = 0;
	if (ubatch && copy_from_user(&batch, ubatch, sizeof(batch)))
		return -EFAULT;

	if (batch >= htab->n_buckets)
		return -ENOENT;

	key_size = htab->map.key_size;
	roundup_key_size = round_up(htab->map.key_size, 8);
	value_size = htab->map.value_size;
	size = round_up(value_size, 8);
	if (is_percpu)
		value_size = size * num_possible_cpus();
	total = 0;
	/* while experimenting with hash tables with sizes ranging from 10 to
	 * 1000, it was observed that a bucket can have upto 5 entries.
	 */
	bucket_size = 5;

alloc:
	/* We cannot do copy_from_user or copy_to_user inside
	 * the rcu_read_lock. Allocate enough space here.
	 */
	keys = kvmalloc_array(key_size, bucket_size, GFP_USER | __GFP_NOWARN);
	values = kvmalloc_array(value_size, bucket_size, GFP_USER | __GFP_NOWARN);
	if (!keys || !values) {
		ret = -ENOMEM;
		goto after_loop;
	}

again:
	bpf_disable_instrumentation();
	rcu_read_lock();
again_nocopy:
	dst_key = keys;
	dst_val = values;
	b = &htab->buckets[batch];
	head = &b->head;
	/* do not grab the lock unless need it (bucket_cnt > 0). */
	if (locked) {
		ret = htab_lock_bucket(htab, b, batch, &flags);
		if (ret)
			goto next_batch;
	}

	bucket_cnt = 0;
	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		bucket_cnt++;

	if (bucket_cnt && !locked) {
		locked = true;
		goto again_nocopy;
	}

	if (bucket_cnt > (max_count - total)) {
		if (total == 0)
			ret = -ENOSPC;
		/* Note that since bucket_cnt > 0 here, it is implicit
		 * that the locked was grabbed, so release it.
		 */
		htab_unlock_bucket(htab, b, batch, flags);
		rcu_read_unlock();
		bpf_enable_instrumentation();
		goto after_loop;
	}

	if (bucket_cnt > bucket_size) {
		bucket_size = bucket_cnt;
		/* Note that since bucket_cnt > 0 here, it is implicit
		 * that the locked was grabbed, so release it.
		 */
		htab_unlock_bucket(htab, b, batch, flags);
		rcu_read_unlock();
		bpf_enable_instrumentation();
		kvfree(keys);
		kvfree(values);
		goto alloc;
	}

	/* Next block is only safe to run if you have grabbed the lock */
	if (!locked)
		goto next_batch;

	hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
		memcpy(dst_key, l->key, key_size);

		if (is_percpu) {
			int off = 0, cpu;
			void __percpu *pptr;

			pptr = htab_elem_get_ptr(l, map->key_size);
			for_each_possible_cpu(cpu) {
				bpf_long_memcpy(dst_val + off,
						per_cpu_ptr(pptr, cpu), size);
				off += size;
			}
		} else {
			value = l->key + roundup_key_size;
			if (elem_map_flags & BPF_F_LOCK)
				copy_map_value_locked(map, dst_val, value,
						      true);
			else
				copy_map_value(map, dst_val, value);
			check_and_init_map_lock(map, dst_val);
		}
		if (do_delete) {
			hlist_nulls_del_rcu(&l->hash_node);

			/* bpf_lru_push_free() will acquire lru_lock, which
			 * may cause deadlock. See comments in function
			 * prealloc_lru_pop(). Let us do bpf_lru_push_free()
			 * after releasing the bucket lock.
			 */
			if (is_lru_map) {
				l->batch_flink = node_to_free;
				node_to_free = l;
			} else {
				free_htab_elem(htab, l);
			}
		}
		dst_key += key_size;
		dst_val += value_size;
	}

	htab_unlock_bucket(htab, b, batch, flags);
	locked = false;

	while (node_to_free) {
		l = node_to_free;
		node_to_free = node_to_free->batch_flink;
		bpf_lru_push_free(&htab->lru, &l->lru_node);
	}

next_batch:
	/* If we are not copying data, we can go to next bucket and avoid
	 * unlocking the rcu.
	 */
	if (!bucket_cnt && (batch + 1 < htab->n_buckets)) {
		batch++;
		goto again_nocopy;
	}

	rcu_read_unlock();
	bpf_enable_instrumentation();
	if (bucket_cnt && (copy_to_user(ukeys + total * key_size, keys,
	    key_size * bucket_cnt) ||
	    copy_to_user(uvalues + total * value_size, values,
	    value_size * bucket_cnt))) {
		ret = -EFAULT;
		goto after_loop;
	}

	total += bucket_cnt;
	batch++;
	if (batch >= htab->n_buckets) {
		ret = -ENOENT;
		goto after_loop;
	}
	goto again;

after_loop:
	if (ret == -EFAULT)
		goto out;

	/* copy # of entries and next batch */
	ubatch = u64_to_user_ptr(attr->batch.out_batch);
	if (copy_to_user(ubatch, &batch, sizeof(batch)) ||
	    put_user(total, &uattr->batch.count))
		ret = -EFAULT;

out:
	kvfree(keys);
	kvfree(values);
	return ret;
}

Project: bpf
File: hashtab.c

static void *htab_lru_map_lookup_elem_sys(struct bpf_map *map, void *key)
{
	return __htab_lru_map_lookup_elem(map, key, false);
}

Project: bpf
File: hashtab.c

static void prealloc_destroy(struct bpf_htab *htab)
{
	htab_free_elems(htab);

	if (htab_is_lru(htab))
		bpf_lru_destroy(&htab->lru);
	else
		pcpu_freelist_destroy(&htab->freelist);
}

Project: bpf
File: hashtab.c

static inline struct hlist_nulls_head *select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &__select_bucket(htab, hash)->head;
}

Project: bpf
File: hashtab.c

htab_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
		      union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  false, false);
}

Project: bpf
File: hashtab.c

static struct htab_elem *get_htab_elem(struct bpf_htab *htab, int i)
{
	return (struct htab_elem *) (htab->elems + i * (u64)htab->elem_size);
}

Project: bpf
File: hashtab.c

static struct htab_elem *lookup_nulls_elem_raw(struct hlist_nulls_head *head,
					       u32 hash, void *key,
					       u32 key_size, u32 n_buckets)
{
	struct hlist_nulls_node *n;
	struct htab_elem *l;

again:
	hlist_nulls_for_each_entry_rcu(l, n, head, hash_node)
		if (l->hash == hash && !memcmp(&l->key, key, key_size))
			return l;

	if (unlikely(get_nulls_value(n) != (hash & (n_buckets - 1))))
		goto again;

	return NULL;
}

Project: bpf
File: hashtab.c

static void htab_free_elems(struct bpf_htab *htab)
{
	int i;

	if (!htab_is_percpu(htab))
		goto free_elems;

	for (i = 0; i < htab->map.max_entries; i++) {
		void __percpu *pptr;

		pptr = htab_elem_get_ptr(get_htab_elem(htab, i),
					 htab->map.key_size);
		free_percpu(pptr);
		cond_resched();
	}
free_elems:
	bpf_map_area_free(htab->elems);
}

Project: bpf
File: hashtab.c

static int fd_htab_map_alloc_check(union bpf_attr *attr)
{
	if (attr->value_size != sizeof(u32))
		return -EINVAL;
	return htab_map_alloc_check(attr);
}

Project: bpf
File: hashtab.c

static int htab_lru_map_lookup_and_delete_elem(struct bpf_map *map, void *key,
					       void *value, u64 flags)
{
	return __htab_map_lookup_and_delete_elem(map, key, value, true, false,
						 flags);
}

Project: bpf
File: hashtab.c

static int htab_lru_map_gen_lookup(struct bpf_map *map,
				   struct bpf_insn *insn_buf)
{
	struct bpf_insn *insn = insn_buf;
	const int ret = BPF_REG_0;
	const int ref_reg = BPF_REG_1;

	BUILD_BUG_ON(!__same_type(&__htab_map_lookup_elem,
		     (void *(*)(struct bpf_map *map, void *key))NULL));
	*insn++ = BPF_EMIT_CALL(BPF_CAST_CALL(__htab_map_lookup_elem));
	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 4);
	*insn++ = BPF_LDX_MEM(BPF_B, ref_reg, ret,
			      offsetof(struct htab_elem, lru_node) +
			      offsetof(struct bpf_lru_node, ref));
	*insn++ = BPF_JMP_IMM(BPF_JNE, ref_reg, 0, 1);
	*insn++ = BPF_ST_MEM(BPF_B, ret,
			     offsetof(struct htab_elem, lru_node) +
			     offsetof(struct bpf_lru_node, ref),
			     1);
	*insn++ = BPF_ALU64_IMM(BPF_ADD, ret,
				offsetof(struct htab_elem, key) +
				round_up(map->key_size, 8));
	return insn - insn_buf;
}

Project: bpf
File: hashtab.c

static inline void htab_elem_set_ptr(struct htab_elem *l, u32 key_size,
				     void __percpu *pptr)
{
	*(void __percpu **)(l->key + key_size) = pptr;
}

Project: bpf
File: hashtab.c

static bool htab_is_lru(const struct bpf_htab *htab)
{
	return htab->map.map_type == BPF_MAP_TYPE_LRU_HASH ||
		htab->map.map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH;
}

Project: bpf
File: hashtab.c

static void fd_htab_map_free(struct bpf_map *map)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_nulls_node *n;
	struct hlist_nulls_head *head;
	struct htab_elem *l;
	int i;

	for (i = 0; i < htab->n_buckets; i++) {
		head = select_bucket(htab, i);

		hlist_nulls_for_each_entry_safe(l, n, head, hash_node) {
			void *ptr = fd_htab_map_get_ptr(map, l);

			map->ops->map_fd_put_ptr(ptr);
		}
	}

	htab_map_free(map);
}

Project: bpf
File: hashtab.c

static inline void htab_unlock_bucket(const struct bpf_htab *htab,
				      struct bucket *b, u32 hash,
				      unsigned long flags)
{
	hash = hash & HASHTAB_MAP_LOCK_MASK;
	if (htab_use_raw_lock(htab))
		raw_spin_unlock_irqrestore(&b->raw_lock, flags);
	else
		spin_unlock_irqrestore(&b->lock, flags);
	__this_cpu_dec(*(htab->map_locked[hash]));
	migrate_enable();
}

Project: bpf
File: hashtab.c

static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
					 void *value, u32 key_size, u32 hash,
					 bool percpu, bool onallcpus,
					 struct htab_elem *old_elem)
{
	u32 size = htab->map.value_size;
	bool prealloc = htab_is_prealloc(htab);
	struct htab_elem *l_new, **pl_new;
	void __percpu *pptr;

	if (prealloc) {
		if (old_elem) {
			/* if we're updating the existing element,
			 * use per-cpu extra elems to avoid freelist_pop/push
			 */
			pl_new = this_cpu_ptr(htab->extra_elems);
			l_new = *pl_new;
			htab_put_fd_value(htab, old_elem);
			*pl_new = old_elem;
		} else {
			struct pcpu_freelist_node *l;

			l = __pcpu_freelist_pop(&htab->freelist);
			if (!l)
				return ERR_PTR(-E2BIG);
			l_new = container_of(l, struct htab_elem, fnode);
		}
	} else {
		if (atomic_inc_return(&htab->count) > htab->map.max_entries)
			if (!old_elem) {
				/* when map is full and update() is replacing
				 * old element, it's ok to allocate, since
				 * old element will be freed immediately.
				 * Otherwise return an error
				 */
				l_new = ERR_PTR(-E2BIG);
				goto dec_count;
			}
		l_new = bpf_map_kmalloc_node(&htab->map, htab->elem_size,
					     GFP_ATOMIC | __GFP_NOWARN,
					     htab->map.numa_node);
		if (!l_new) {
			l_new = ERR_PTR(-ENOMEM);
			goto dec_count;
		}
		check_and_init_map_lock(&htab->map,
					l_new->key + round_up(key_size, 8));
	}

	memcpy(l_new->key, key, key_size);
	if (percpu) {
		size = round_up(size, 8);
		if (prealloc) {
			pptr = htab_elem_get_ptr(l_new, key_size);
		} else {
			/* alloc_percpu zero-fills */
			pptr = bpf_map_alloc_percpu(&htab->map, size, 8,
						    GFP_ATOMIC | __GFP_NOWARN);
			if (!pptr) {
				kfree(l_new);
				l_new = ERR_PTR(-ENOMEM);
				goto dec_count;
			}
		}

		pcpu_init_value(htab, pptr, value, onallcpus);

		if (!prealloc)
			htab_elem_set_ptr(l_new, key_size, pptr);
	} else if (fd_htab_map_needs_adjust(htab)) {
		size = round_up(size, 8);
		memcpy(l_new->key + round_up(key_size, 8), value, size);
	} else {
		copy_map_value(&htab->map,
			       l_new->key + round_up(key_size, 8),
			       value);
	}

	l_new->hash = hash;
	return l_new;
dec_count:
	atomic_dec(&htab->count);
	return l_new;
}

Project: bpf
File: hashtab.c

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_nulls_head *head;
	struct htab_elem *l, *next_l;
	u32 hash, key_size;
	int i = 0;

	WARN_ON_ONCE(!rcu_read_lock_held());

	key_size = map->key_size;

	if (!key)
		goto find_first_elem;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	head = select_bucket(htab, hash);

	/* lookup the key */
	l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);

	if (!l)
		goto find_first_elem;

	/* key was found, get next key in the same bucket */
	next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_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_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_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;
		}
	}

	/* iterated over all buckets and all elements */
	return -ENOENT;
}

Project: bpf
File: hashtab.c

static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
					  u32 hash)
{
	struct bpf_lru_node *node = bpf_lru_pop_free(&htab->lru, hash);
	struct htab_elem *l;

	if (node) {
		l = container_of(node, struct htab_elem, lru_node);
		memcpy(l->key, key, htab->map.key_size);
		return l;
	}

	return NULL;
}

Project: bpf
File: hashtab.c

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 = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	if (unlikely(map_flags & BPF_F_LOCK)) {
		if (unlikely(!map_value_has_spin_lock(map)))
			return -EINVAL;
		/* find an element without taking the bucket lock */
		l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
					      htab->n_buckets);
		ret = check_flags(htab, l_old, map_flags);
		if (ret)
			return ret;
		if (l_old) {
			/* grab the element lock and update value in place */
			copy_map_value_locked(map,
					      l_old->key + round_up(key_size, 8),
					      value, false);
			return 0;
		}
		/* fall through, grab the bucket lock and lookup again.
		 * 99.9% chance that the element won't be found,
		 * but second lookup under lock has to be done.
		 */
	}

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
		/* first lookup without the bucket lock didn't find the element,
		 * but second lookup with the bucket lock found it.
		 * This case is highly unlikely, but has to be dealt with:
		 * grab the element lock in addition to the bucket lock
		 * and update element in place
		 */
		copy_map_value_locked(map,
				      l_old->key + round_up(key_size, 8),
				      value, false);
		ret = 0;
		goto err;
	}

	l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
				l_old);
	if (IS_ERR(l_new)) {
		/* all pre-allocated elements are in use or memory exhausted */
		ret = PTR_ERR(l_new);
		goto err;
	}

	/* add new element to the head of the list, so that
	 * concurrent search will find it before old elem
	 */
	hlist_nulls_add_head_rcu(&l_new->hash_node, head);
	if (l_old) {
		hlist_nulls_del_rcu(&l_old->hash_node);
		if (!htab_is_prealloc(htab))
			free_htab_elem(htab, l_old);
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	return ret;
}

Project: bpf
File: hashtab.c

static void htab_of_map_free(struct bpf_map *map)
{
	bpf_map_meta_free(map->inner_map_meta);
	fd_htab_map_free(map);
}

Project: bpf
File: hashtab.c

static void *htab_lru_map_lookup_elem(struct bpf_map *map, void *key)
{
	return __htab_lru_map_lookup_elem(map, key, true);
}

Project: bpf
File: hashtab.c

htab_percpu_map_lookup_batch(struct bpf_map *map, const union bpf_attr *attr,
			     union bpf_attr __user *uattr)
{
	return __htab_map_lookup_and_delete_batch(map, attr, uattr, false,
						  false, true);
}

Project: bpf
File: hashtab.c

static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key,
					     void *value, u64 map_flags,
					     bool onallcpus)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new = NULL, *l_old;
	struct hlist_nulls_head *head;
	unsigned long flags;
	struct bucket *b;
	u32 key_size, hash;
	int ret;

	if (unlikely(map_flags > BPF_EXIST))
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held() && !rcu_read_lock_trace_held() &&
		     !rcu_read_lock_bh_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size, htab->hashrnd);

	b = __select_bucket(htab, hash);
	head = &b->head;

	/* For LRU, we need to alloc before taking bucket's
	 * spinlock because LRU's elem alloc may need
	 * to remove older elem from htab and this removal
	 * operation will need a bucket lock.
	 */
	if (map_flags != BPF_EXIST) {
		l_new = prealloc_lru_pop(htab, key, hash);
		if (!l_new)
			return -ENOMEM;
	}

	ret = htab_lock_bucket(htab, b, hash, &flags);
	if (ret)
		return ret;

	l_old = lookup_elem_raw(head, hash, key, key_size);

	ret = check_flags(htab, l_old, map_flags);
	if (ret)
		goto err;

	if (l_old) {
		bpf_lru_node_set_ref(&l_old->lru_node);

		/* per-cpu hash map can update value in-place */
		pcpu_copy_value(htab, htab_elem_get_ptr(l_old, key_size),
				value, onallcpus);
	} else {
		pcpu_init_value(htab, htab_elem_get_ptr(l_new, key_size),
				value, onallcpus);
		hlist_nulls_add_head_rcu(&l_new->hash_node, head);
		l_new = NULL;
	}
	ret = 0;
err:
	htab_unlock_bucket(htab, b, hash, flags);
	if (l_new)
		bpf_lru_push_free(&htab->lru, &l_new->lru_node);
	return ret;
}