bpf, sockmap: convert to generic sk_msg interface

Add a generic sk_msg layer, and convert current sockmap and later
kTLS over to make use of it. While sk_buff handles network packet
representation from netdevice up to socket, sk_msg handles data
representation from application to socket layer.

This means that sk_msg framework spans across ULP users in the
kernel, and enables features such as introspection or filtering
of data with the help of BPF programs that operate on this data
structure.

Latter becomes in particular useful for kTLS where data encryption
is deferred into the kernel, and as such enabling the kernel to
perform L7 introspection and policy based on BPF for TLS connections
where the record is being encrypted after BPF has run and came to
a verdict. In order to get there, first step is to transform open
coding of scatter-gather list handling into a common core framework
that subsystems can use.

The code itself has been split and refactored into three bigger
pieces: i) the generic sk_msg API which deals with managing the
scatter gather ring, providing helpers for walking and mangling,
transferring application data from user space into it, and preparing
it for BPF pre/post-processing, ii) the plain sock map itself
where sockets can be attached to or detached from; these bits
are independent of i) which can now be used also without sock
map, and iii) the integration with plain TCP as one protocol
to be used for processing L7 application data (later this could
e.g. also be extended to other protocols like UDP). The semantics
are the same with the old sock map code and therefore no change
of user facing behavior or APIs. While pursuing this work it
also helped finding a number of bugs in the old sockmap code
that we've fixed already in earlier commits. The test_sockmap
kselftest suite passes through fine as well.

Joint work with John.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 1002 insertions, 0 deletions

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
new file mode 100644
index 000000000000..3c0e44cb811a
--- /dev/null
+++ b/net/core/sock_map.c
@@ -0,0 +1,1002 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2017 - 2018 Covalent IO, Inc. http://covalent.io */
+
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/net.h>
+#include <linux/workqueue.h>
+#include <linux/skmsg.h>
+#include <linux/list.h>
+#include <linux/jhash.h>
+
+struct bpf_stab {
+	struct bpf_map map;
+	struct sock **sks;
+	struct sk_psock_progs progs;
+	raw_spinlock_t lock;
+};
+
+#define SOCK_CREATE_FLAG_MASK				\
+	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
+
+static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
+{
+	struct bpf_stab *stab;
+	u64 cost;
+	int err;
+
+	if (!capable(CAP_NET_ADMIN))
+		return ERR_PTR(-EPERM);
+	if (attr->max_entries == 0 ||
+	    attr->key_size    != 4 ||
+	    attr->value_size  != 4 ||
+	    attr->map_flags & ~SOCK_CREATE_FLAG_MASK)
+		return ERR_PTR(-EINVAL);
+
+	stab = kzalloc(sizeof(*stab), GFP_USER);
+	if (!stab)
+		return ERR_PTR(-ENOMEM);
+
+	bpf_map_init_from_attr(&stab->map, attr);
+	raw_spin_lock_init(&stab->lock);
+
+	/* Make sure page count doesn't overflow. */
+	cost = (u64) stab->map.max_entries * sizeof(struct sock *);
+	if (cost >= U32_MAX - PAGE_SIZE) {
+		err = -EINVAL;
+		goto free_stab;
+	}
+
+	stab->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
+	err = bpf_map_precharge_memlock(stab->map.pages);
+	if (err)
+		goto free_stab;
+
+	stab->sks = bpf_map_area_alloc(stab->map.max_entries *
+				       sizeof(struct sock *),
+				       stab->map.numa_node);
+	if (stab->sks)
+		return &stab->map;
+	err = -ENOMEM;
+free_stab:
+	kfree(stab);
+	return ERR_PTR(err);
+}
+
+int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+	u32 ufd = attr->target_fd;
+	struct bpf_map *map;
+	struct fd f;
+	int ret;
+
+	f = fdget(ufd);
+	map = __bpf_map_get(f);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	ret = sock_map_prog_update(map, prog, attr->attach_type);
+	fdput(f);
+	return ret;
+}
+
+static void sock_map_sk_acquire(struct sock *sk)
+	__acquires(&sk->sk_lock.slock)
+{
+	lock_sock(sk);
+	preempt_disable();
+	rcu_read_lock();
+}
+
+static void sock_map_sk_release(struct sock *sk)
+	__releases(&sk->sk_lock.slock)
+{
+	rcu_read_unlock();
+	preempt_enable();
+	release_sock(sk);
+}
+
+static void sock_map_add_link(struct sk_psock *psock,
+			      struct sk_psock_link *link,
+			      struct bpf_map *map, void *link_raw)
+{
+	link->link_raw = link_raw;
+	link->map = map;
+	spin_lock_bh(&psock->link_lock);
+	list_add_tail(&link->list, &psock->link);
+	spin_unlock_bh(&psock->link_lock);
+}
+
+static void sock_map_del_link(struct sock *sk,
+			      struct sk_psock *psock, void *link_raw)
+{
+	struct sk_psock_link *link, *tmp;
+	bool strp_stop = false;
+
+	spin_lock_bh(&psock->link_lock);
+	list_for_each_entry_safe(link, tmp, &psock->link, list) {
+		if (link->link_raw == link_raw) {
+			struct bpf_map *map = link->map;
+			struct bpf_stab *stab = container_of(map, struct bpf_stab,
+							     map);
+			if (psock->parser.enabled && stab->progs.skb_parser)
+				strp_stop = true;
+			list_del(&link->list);
+			sk_psock_free_link(link);
+		}
+	}
+	spin_unlock_bh(&psock->link_lock);
+	if (strp_stop) {
+		write_lock_bh(&sk->sk_callback_lock);
+		sk_psock_stop_strp(sk, psock);
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+}
+
+static void sock_map_unref(struct sock *sk, void *link_raw)
+{
+	struct sk_psock *psock = sk_psock(sk);
+
+	if (likely(psock)) {
+		sock_map_del_link(sk, psock, link_raw);
+		sk_psock_put(sk, psock);
+	}
+}
+
+static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs,
+			 struct sock *sk)
+{
+	struct bpf_prog *msg_parser, *skb_parser, *skb_verdict;
+	bool skb_progs, sk_psock_is_new = false;
+	struct sk_psock *psock;
+	int ret;
+
+	skb_verdict = READ_ONCE(progs->skb_verdict);
+	skb_parser = READ_ONCE(progs->skb_parser);
+	skb_progs = skb_parser && skb_verdict;
+	if (skb_progs) {
+		skb_verdict = bpf_prog_inc_not_zero(skb_verdict);
+		if (IS_ERR(skb_verdict))
+			return PTR_ERR(skb_verdict);
+		skb_parser = bpf_prog_inc_not_zero(skb_parser);
+		if (IS_ERR(skb_parser)) {
+			bpf_prog_put(skb_verdict);
+			return PTR_ERR(skb_parser);
+		}
+	}
+
+	msg_parser = READ_ONCE(progs->msg_parser);
+	if (msg_parser) {
+		msg_parser = bpf_prog_inc_not_zero(msg_parser);
+		if (IS_ERR(msg_parser)) {
+			ret = PTR_ERR(msg_parser);
+			goto out;
+		}
+	}
+
+	psock = sk_psock_get(sk);
+	if (psock) {
+		if (!sk_has_psock(sk)) {
+			ret = -EBUSY;
+			goto out_progs;
+		}
+		if ((msg_parser && READ_ONCE(psock->progs.msg_parser)) ||
+		    (skb_progs  && READ_ONCE(psock->progs.skb_parser))) {
+			sk_psock_put(sk, psock);
+			ret = -EBUSY;
+			goto out_progs;
+		}
+	} else {
+		psock = sk_psock_init(sk, map->numa_node);
+		if (!psock) {
+			ret = -ENOMEM;
+			goto out_progs;
+		}
+		sk_psock_is_new = true;
+	}
+
+	if (msg_parser)
+		psock_set_prog(&psock->progs.msg_parser, msg_parser);
+	if (sk_psock_is_new) {
+		ret = tcp_bpf_init(sk);
+		if (ret < 0)
+			goto out_drop;
+	} else {
+		tcp_bpf_reinit(sk);
+	}
+
+	write_lock_bh(&sk->sk_callback_lock);
+	if (skb_progs && !psock->parser.enabled) {
+		ret = sk_psock_init_strp(sk, psock);
+		if (ret) {
+			write_unlock_bh(&sk->sk_callback_lock);
+			goto out_drop;
+		}
+		psock_set_prog(&psock->progs.skb_verdict, skb_verdict);
+		psock_set_prog(&psock->progs.skb_parser, skb_parser);
+		sk_psock_start_strp(sk, psock);
+	}
+	write_unlock_bh(&sk->sk_callback_lock);
+	return 0;
+out_drop:
+	sk_psock_put(sk, psock);
+out_progs:
+	if (msg_parser)
+		bpf_prog_put(msg_parser);
+out:
+	if (skb_progs) {
+		bpf_prog_put(skb_verdict);
+		bpf_prog_put(skb_parser);
+	}
+	return ret;
+}
+
+static void sock_map_free(struct bpf_map *map)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+	int i;
+
+	synchronize_rcu();
+	rcu_read_lock();
+	raw_spin_lock_bh(&stab->lock);
+	for (i = 0; i < stab->map.max_entries; i++) {
+		struct sock **psk = &stab->sks[i];
+		struct sock *sk;
+
+		sk = xchg(psk, NULL);
+		if (sk)
+			sock_map_unref(sk, psk);
+	}
+	raw_spin_unlock_bh(&stab->lock);
+	rcu_read_unlock();
+
+	bpf_map_area_free(stab->sks);
+	kfree(stab);
+}
+
+static void sock_map_release_progs(struct bpf_map *map)
+{
+	psock_progs_drop(&container_of(map, struct bpf_stab, map)->progs);
+}
+
+static struct sock *__sock_map_lookup_elem(struct bpf_map *map, u32 key)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (unlikely(key >= map->max_entries))
+		return NULL;
+	return READ_ONCE(stab->sks[key]);
+}
+
+static void *sock_map_lookup(struct bpf_map *map, void *key)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test,
+			     struct sock **psk)
+{
+	struct sock *sk;
+
+	raw_spin_lock_bh(&stab->lock);
+	sk = *psk;
+	if (!sk_test || sk_test == sk)
+		*psk = NULL;
+	raw_spin_unlock_bh(&stab->lock);
+	if (unlikely(!sk))
+		return -EINVAL;
+	sock_map_unref(sk, psk);
+	return 0;
+}
+
+static void sock_map_delete_from_link(struct bpf_map *map, struct sock *sk,
+				      void *link_raw)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+
+	__sock_map_delete(stab, sk, link_raw);
+}
+
+static int sock_map_delete_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+	u32 i = *(u32 *)key;
+	struct sock **psk;
+
+	if (unlikely(i >= map->max_entries))
+		return -EINVAL;
+
+	psk = &stab->sks[i];
+	return __sock_map_delete(stab, NULL, psk);
+}
+
+static int sock_map_get_next_key(struct bpf_map *map, void *key, void *next)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+	u32 i = key ? *(u32 *)key : U32_MAX;
+	u32 *key_next = next;
+
+	if (i == stab->map.max_entries - 1)
+		return -ENOENT;
+	if (i >= stab->map.max_entries)
+		*key_next = 0;
+	else
+		*key_next = i + 1;
+	return 0;
+}
+
+static int sock_map_update_common(struct bpf_map *map, u32 idx,
+				  struct sock *sk, u64 flags)
+{
+	struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
+	struct sk_psock_link *link;
+	struct sk_psock *psock;
+	struct sock *osk;
+	int ret;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	if (unlikely(flags > BPF_EXIST))
+		return -EINVAL;
+	if (unlikely(idx >= map->max_entries))
+		return -E2BIG;
+
+	link = sk_psock_init_link();
+	if (!link)
+		return -ENOMEM;
+
+	ret = sock_map_link(map, &stab->progs, sk);
+	if (ret < 0)
+		goto out_free;
+
+	psock = sk_psock(sk);
+	WARN_ON_ONCE(!psock);
+
+	raw_spin_lock_bh(&stab->lock);
+	osk = stab->sks[idx];
+	if (osk && flags == BPF_NOEXIST) {
+		ret = -EEXIST;
+		goto out_unlock;
+	} else if (!osk && flags == BPF_EXIST) {
+		ret = -ENOENT;
+		goto out_unlock;
+	}
+
+	sock_map_add_link(psock, link, map, &stab->sks[idx]);
+	stab->sks[idx] = sk;
+	if (osk)
+		sock_map_unref(osk, &stab->sks[idx]);
+	raw_spin_unlock_bh(&stab->lock);
+	return 0;
+out_unlock:
+	raw_spin_unlock_bh(&stab->lock);
+	if (psock)
+		sk_psock_put(sk, psock);
+out_free:
+	sk_psock_free_link(link);
+	return ret;
+}
+
+static bool sock_map_op_okay(const struct bpf_sock_ops_kern *ops)
+{
+	return ops->op == BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB ||
+	       ops->op == BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB;
+}
+
+static bool sock_map_sk_is_suitable(const struct sock *sk)
+{
+	return sk->sk_type == SOCK_STREAM &&
+	       sk->sk_protocol == IPPROTO_TCP;
+}
+
+static int sock_map_update_elem(struct bpf_map *map, void *key,
+				void *value, u64 flags)
+{
+	u32 ufd = *(u32 *)value;
+	u32 idx = *(u32 *)key;
+	struct socket *sock;
+	struct sock *sk;
+	int ret;
+
+	sock = sockfd_lookup(ufd, &ret);
+	if (!sock)
+		return ret;
+	sk = sock->sk;
+	if (!sk) {
+		ret = -EINVAL;
+		goto out;
+	}
+	if (!sock_map_sk_is_suitable(sk) ||
+	    sk->sk_state != TCP_ESTABLISHED) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	sock_map_sk_acquire(sk);
+	ret = sock_map_update_common(map, idx, sk, flags);
+	sock_map_sk_release(sk);
+out:
+	fput(sock->file);
+	return ret;
+}
+
+BPF_CALL_4(bpf_sock_map_update, struct bpf_sock_ops_kern *, sops,
+	   struct bpf_map *, map, void *, key, u64, flags)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (likely(sock_map_sk_is_suitable(sops->sk) &&
+		   sock_map_op_okay(sops)))
+		return sock_map_update_common(map, *(u32 *)key, sops->sk,
+					      flags);
+	return -EOPNOTSUPP;
+}
+
+const struct bpf_func_proto bpf_sock_map_update_proto = {
+	.func		= bpf_sock_map_update,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_CONST_MAP_PTR,
+	.arg3_type	= ARG_PTR_TO_MAP_KEY,
+	.arg4_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
+	   struct bpf_map *, map, u32, key, u64, flags)
+{
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+	if (unlikely(flags & ~(BPF_F_INGRESS)))
+		return SK_DROP;
+	tcb->bpf.flags = flags;
+	tcb->bpf.sk_redir = __sock_map_lookup_elem(map, key);
+	if (!tcb->bpf.sk_redir)
+		return SK_DROP;
+	return SK_PASS;
+}
+
+const struct bpf_func_proto bpf_sk_redirect_map_proto = {
+	.func           = bpf_sk_redirect_map,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_CONST_MAP_PTR,
+	.arg3_type      = ARG_ANYTHING,
+	.arg4_type      = ARG_ANYTHING,
+};
+
+BPF_CALL_4(bpf_msg_redirect_map, struct sk_msg *, msg,
+	   struct bpf_map *, map, u32, key, u64, flags)
+{
+	if (unlikely(flags & ~(BPF_F_INGRESS)))
+		return SK_DROP;
+	msg->flags = flags;
+	msg->sk_redir = __sock_map_lookup_elem(map, key);
+	if (!msg->sk_redir)
+		return SK_DROP;
+	return SK_PASS;
+}
+
+const struct bpf_func_proto bpf_msg_redirect_map_proto = {
+	.func           = bpf_msg_redirect_map,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_CONST_MAP_PTR,
+	.arg3_type      = ARG_ANYTHING,
+	.arg4_type      = ARG_ANYTHING,
+};
+
+const struct bpf_map_ops sock_map_ops = {
+	.map_alloc		= sock_map_alloc,
+	.map_free		= sock_map_free,
+	.map_get_next_key	= sock_map_get_next_key,
+	.map_update_elem	= sock_map_update_elem,
+	.map_delete_elem	= sock_map_delete_elem,
+	.map_lookup_elem	= sock_map_lookup,
+	.map_release_uref	= sock_map_release_progs,
+	.map_check_btf		= map_check_no_btf,
+};
+
+struct bpf_htab_elem {
+	struct rcu_head rcu;
+	u32 hash;
+	struct sock *sk;
+	struct hlist_node node;
+	u8 key[0];
+};
+
+struct bpf_htab_bucket {
+	struct hlist_head head;
+	raw_spinlock_t lock;
+};
+
+struct bpf_htab {
+	struct bpf_map map;
+	struct bpf_htab_bucket *buckets;
+	u32 buckets_num;
+	u32 elem_size;
+	struct sk_psock_progs progs;
+	atomic_t count;
+};
+
+static inline u32 sock_hash_bucket_hash(const void *key, u32 len)
+{
+	return jhash(key, len, 0);
+}
+
+static struct bpf_htab_bucket *sock_hash_select_bucket(struct bpf_htab *htab,
+						       u32 hash)
+{
+	return &htab->buckets[hash & (htab->buckets_num - 1)];
+}
+
+static struct bpf_htab_elem *
+sock_hash_lookup_elem_raw(struct hlist_head *head, u32 hash, void *key,
+			  u32 key_size)
+{
+	struct bpf_htab_elem *elem;
+
+	hlist_for_each_entry_rcu(elem, head, node) {
+		if (elem->hash == hash &&
+		    !memcmp(&elem->key, key, key_size))
+			return elem;
+	}
+
+	return NULL;
+}
+
+static struct sock *__sock_hash_lookup_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	u32 key_size = map->key_size, hash;
+	struct bpf_htab_bucket *bucket;
+	struct bpf_htab_elem *elem;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	hash = sock_hash_bucket_hash(key, key_size);
+	bucket = sock_hash_select_bucket(htab, hash);
+	elem = sock_hash_lookup_elem_raw(&bucket->head, hash, key, key_size);
+
+	return elem ? elem->sk : NULL;
+}
+
+static void sock_hash_free_elem(struct bpf_htab *htab,
+				struct bpf_htab_elem *elem)
+{
+	atomic_dec(&htab->count);
+	kfree_rcu(elem, rcu);
+}
+
+static void sock_hash_delete_from_link(struct bpf_map *map, struct sock *sk,
+				       void *link_raw)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct bpf_htab_elem *elem_probe, *elem = link_raw;
+	struct bpf_htab_bucket *bucket;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	bucket = sock_hash_select_bucket(htab, elem->hash);
+
+	/* elem may be deleted in parallel from the map, but access here
+	 * is okay since it's going away only after RCU grace period.
+	 * However, we need to check whether it's still present.
+	 */
+	raw_spin_lock_bh(&bucket->lock);
+	elem_probe = sock_hash_lookup_elem_raw(&bucket->head, elem->hash,
+					       elem->key, map->key_size);
+	if (elem_probe && elem_probe == elem) {
+		hlist_del_rcu(&elem->node);
+		sock_map_unref(elem->sk, elem);
+		sock_hash_free_elem(htab, elem);
+	}
+	raw_spin_unlock_bh(&bucket->lock);
+}
+
+static int sock_hash_delete_elem(struct bpf_map *map, void *key)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	u32 hash, key_size = map->key_size;
+	struct bpf_htab_bucket *bucket;
+	struct bpf_htab_elem *elem;
+	int ret = -ENOENT;
+
+	hash = sock_hash_bucket_hash(key, key_size);
+	bucket = sock_hash_select_bucket(htab, hash);
+
+	raw_spin_lock_bh(&bucket->lock);
+	elem = sock_hash_lookup_elem_raw(&bucket->head, hash, key, key_size);
+	if (elem) {
+		hlist_del_rcu(&elem->node);
+		sock_map_unref(elem->sk, elem);
+		sock_hash_free_elem(htab, elem);
+		ret = 0;
+	}
+	raw_spin_unlock_bh(&bucket->lock);
+	return ret;
+}
+
+static struct bpf_htab_elem *sock_hash_alloc_elem(struct bpf_htab *htab,
+						  void *key, u32 key_size,
+						  u32 hash, struct sock *sk,
+						  struct bpf_htab_elem *old)
+{
+	struct bpf_htab_elem *new;
+
+	if (atomic_inc_return(&htab->count) > htab->map.max_entries) {
+		if (!old) {
+			atomic_dec(&htab->count);
+			return ERR_PTR(-E2BIG);
+		}
+	}
+
+	new = kmalloc_node(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN,
+			   htab->map.numa_node);
+	if (!new) {
+		atomic_dec(&htab->count);
+		return ERR_PTR(-ENOMEM);
+	}
+	memcpy(new->key, key, key_size);
+	new->sk = sk;
+	new->hash = hash;
+	return new;
+}
+
+static int sock_hash_update_common(struct bpf_map *map, void *key,
+				   struct sock *sk, u64 flags)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	u32 key_size = map->key_size, hash;
+	struct bpf_htab_elem *elem, *elem_new;
+	struct bpf_htab_bucket *bucket;
+	struct sk_psock_link *link;
+	struct sk_psock *psock;
+	int ret;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	if (unlikely(flags > BPF_EXIST))
+		return -EINVAL;
+
+	link = sk_psock_init_link();
+	if (!link)
+		return -ENOMEM;
+
+	ret = sock_map_link(map, &htab->progs, sk);
+	if (ret < 0)
+		goto out_free;
+
+	psock = sk_psock(sk);
+	WARN_ON_ONCE(!psock);
+
+	hash = sock_hash_bucket_hash(key, key_size);
+	bucket = sock_hash_select_bucket(htab, hash);
+
+	raw_spin_lock_bh(&bucket->lock);
+	elem = sock_hash_lookup_elem_raw(&bucket->head, hash, key, key_size);
+	if (elem && flags == BPF_NOEXIST) {
+		ret = -EEXIST;
+		goto out_unlock;
+	} else if (!elem && flags == BPF_EXIST) {
+		ret = -ENOENT;
+		goto out_unlock;
+	}
+
+	elem_new = sock_hash_alloc_elem(htab, key, key_size, hash, sk, elem);
+	if (IS_ERR(elem_new)) {
+		ret = PTR_ERR(elem_new);
+		goto out_unlock;
+	}
+
+	sock_map_add_link(psock, link, map, elem_new);
+	/* Add new element to the head of the list, so that
+	 * concurrent search will find it before old elem.
+	 */
+	hlist_add_head_rcu(&elem_new->node, &bucket->head);
+	if (elem) {
+		hlist_del_rcu(&elem->node);
+		sock_map_unref(elem->sk, elem);
+		sock_hash_free_elem(htab, elem);
+	}
+	raw_spin_unlock_bh(&bucket->lock);
+	return 0;
+out_unlock:
+	raw_spin_unlock_bh(&bucket->lock);
+	sk_psock_put(sk, psock);
+out_free:
+	sk_psock_free_link(link);
+	return ret;
+}
+
+static int sock_hash_update_elem(struct bpf_map *map, void *key,
+				 void *value, u64 flags)
+{
+	u32 ufd = *(u32 *)value;
+	struct socket *sock;
+	struct sock *sk;
+	int ret;
+
+	sock = sockfd_lookup(ufd, &ret);
+	if (!sock)
+		return ret;
+	sk = sock->sk;
+	if (!sk) {
+		ret = -EINVAL;
+		goto out;
+	}
+	if (!sock_map_sk_is_suitable(sk) ||
+	    sk->sk_state != TCP_ESTABLISHED) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	sock_map_sk_acquire(sk);
+	ret = sock_hash_update_common(map, key, sk, flags);
+	sock_map_sk_release(sk);
+out:
+	fput(sock->file);
+	return ret;
+}
+
+static int sock_hash_get_next_key(struct bpf_map *map, void *key,
+				  void *key_next)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct bpf_htab_elem *elem, *elem_next;
+	u32 hash, key_size = map->key_size;
+	struct hlist_head *head;
+	int i = 0;
+
+	if (!key)
+		goto find_first_elem;
+	hash = sock_hash_bucket_hash(key, key_size);
+	head = &sock_hash_select_bucket(htab, hash)->head;
+	elem = sock_hash_lookup_elem_raw(head, hash, key, key_size);
+	if (!elem)
+		goto find_first_elem;
+
+	elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&elem->node)),
+				     struct bpf_htab_elem, node);
+	if (elem_next) {
+		memcpy(key_next, elem_next->key, key_size);
+		return 0;
+	}
+
+	i = hash & (htab->buckets_num - 1);
+	i++;
+find_first_elem:
+	for (; i < htab->buckets_num; i++) {
+		head = &sock_hash_select_bucket(htab, i)->head;
+		elem_next = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
+					     struct bpf_htab_elem, node);
+		if (elem_next) {
+			memcpy(key_next, elem_next->key, key_size);
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static struct bpf_map *sock_hash_alloc(union bpf_attr *attr)
+{
+	struct bpf_htab *htab;
+	int i, err;
+	u64 cost;
+
+	if (!capable(CAP_NET_ADMIN))
+		return ERR_PTR(-EPERM);
+	if (attr->max_entries == 0 ||
+	    attr->key_size    == 0 ||
+	    attr->value_size  != 4 ||
+	    attr->map_flags & ~SOCK_CREATE_FLAG_MASK)
+		return ERR_PTR(-EINVAL);
+	if (attr->key_size > MAX_BPF_STACK)
+		return ERR_PTR(-E2BIG);
+
+	htab = kzalloc(sizeof(*htab), GFP_USER);
+	if (!htab)
+		return ERR_PTR(-ENOMEM);
+
+	bpf_map_init_from_attr(&htab->map, attr);
+
+	htab->buckets_num = roundup_pow_of_two(htab->map.max_entries);
+	htab->elem_size = sizeof(struct bpf_htab_elem) +
+			  round_up(htab->map.key_size, 8);
+	if (htab->buckets_num == 0 ||
+	    htab->buckets_num > U32_MAX / sizeof(struct bpf_htab_bucket)) {
+		err = -EINVAL;
+		goto free_htab;
+	}
+
+	cost = (u64) htab->buckets_num * sizeof(struct bpf_htab_bucket) +
+	       (u64) htab->elem_size * htab->map.max_entries;
+	if (cost >= U32_MAX - PAGE_SIZE) {
+		err = -EINVAL;
+		goto free_htab;
+	}
+
+	htab->buckets = bpf_map_area_alloc(htab->buckets_num *
+					   sizeof(struct bpf_htab_bucket),
+					   htab->map.numa_node);
+	if (!htab->buckets) {
+		err = -ENOMEM;
+		goto free_htab;
+	}
+
+	for (i = 0; i < htab->buckets_num; i++) {
+		INIT_HLIST_HEAD(&htab->buckets[i].head);
+		raw_spin_lock_init(&htab->buckets[i].lock);
+	}
+
+	return &htab->map;
+free_htab:
+	kfree(htab);
+	return ERR_PTR(err);
+}
+
+static void sock_hash_free(struct bpf_map *map)
+{
+	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
+	struct bpf_htab_bucket *bucket;
+	struct bpf_htab_elem *elem;
+	struct hlist_node *node;
+	int i;
+
+	synchronize_rcu();
+	rcu_read_lock();
+	for (i = 0; i < htab->buckets_num; i++) {
+		bucket = sock_hash_select_bucket(htab, i);
+		raw_spin_lock_bh(&bucket->lock);
+		hlist_for_each_entry_safe(elem, node, &bucket->head, node) {
+			hlist_del_rcu(&elem->node);
+			sock_map_unref(elem->sk, elem);
+		}
+		raw_spin_unlock_bh(&bucket->lock);
+	}
+	rcu_read_unlock();
+
+	bpf_map_area_free(htab->buckets);
+	kfree(htab);
+}
+
+static void sock_hash_release_progs(struct bpf_map *map)
+{
+	psock_progs_drop(&container_of(map, struct bpf_htab, map)->progs);
+}
+
+BPF_CALL_4(bpf_sock_hash_update, struct bpf_sock_ops_kern *, sops,
+	   struct bpf_map *, map, void *, key, u64, flags)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	if (likely(sock_map_sk_is_suitable(sops->sk) &&
+		   sock_map_op_okay(sops)))
+		return sock_hash_update_common(map, key, sops->sk, flags);
+	return -EOPNOTSUPP;
+}
+
+const struct bpf_func_proto bpf_sock_hash_update_proto = {
+	.func		= bpf_sock_hash_update,
+	.gpl_only	= false,
+	.pkt_access	= true,
+	.ret_type	= RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type	= ARG_CONST_MAP_PTR,
+	.arg3_type	= ARG_PTR_TO_MAP_KEY,
+	.arg4_type	= ARG_ANYTHING,
+};
+
+BPF_CALL_4(bpf_sk_redirect_hash, struct sk_buff *, skb,
+	   struct bpf_map *, map, void *, key, u64, flags)
+{
+	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
+
+	if (unlikely(flags & ~(BPF_F_INGRESS)))
+		return SK_DROP;
+	tcb->bpf.flags = flags;
+	tcb->bpf.sk_redir = __sock_hash_lookup_elem(map, key);
+	if (!tcb->bpf.sk_redir)
+		return SK_DROP;
+	return SK_PASS;
+}
+
+const struct bpf_func_proto bpf_sk_redirect_hash_proto = {
+	.func           = bpf_sk_redirect_hash,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_CONST_MAP_PTR,
+	.arg3_type      = ARG_PTR_TO_MAP_KEY,
+	.arg4_type      = ARG_ANYTHING,
+};
+
+BPF_CALL_4(bpf_msg_redirect_hash, struct sk_msg *, msg,
+	   struct bpf_map *, map, void *, key, u64, flags)
+{
+	if (unlikely(flags & ~(BPF_F_INGRESS)))
+		return SK_DROP;
+	msg->flags = flags;
+	msg->sk_redir = __sock_hash_lookup_elem(map, key);
+	if (!msg->sk_redir)
+		return SK_DROP;
+	return SK_PASS;
+}
+
+const struct bpf_func_proto bpf_msg_redirect_hash_proto = {
+	.func           = bpf_msg_redirect_hash,
+	.gpl_only       = false,
+	.ret_type       = RET_INTEGER,
+	.arg1_type	= ARG_PTR_TO_CTX,
+	.arg2_type      = ARG_CONST_MAP_PTR,
+	.arg3_type      = ARG_PTR_TO_MAP_KEY,
+	.arg4_type      = ARG_ANYTHING,
+};
+
+const struct bpf_map_ops sock_hash_ops = {
+	.map_alloc		= sock_hash_alloc,
+	.map_free		= sock_hash_free,
+	.map_get_next_key	= sock_hash_get_next_key,
+	.map_update_elem	= sock_hash_update_elem,
+	.map_delete_elem	= sock_hash_delete_elem,
+	.map_lookup_elem	= sock_map_lookup,
+	.map_release_uref	= sock_hash_release_progs,
+	.map_check_btf		= map_check_no_btf,
+};
+
+static struct sk_psock_progs *sock_map_progs(struct bpf_map *map)
+{
+	switch (map->map_type) {
+	case BPF_MAP_TYPE_SOCKMAP:
+		return &container_of(map, struct bpf_stab, map)->progs;
+	case BPF_MAP_TYPE_SOCKHASH:
+		return &container_of(map, struct bpf_htab, map)->progs;
+	default:
+		break;
+	}
+
+	return NULL;
+}
+
+int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
+			 u32 which)
+{
+	struct sk_psock_progs *progs = sock_map_progs(map);
+
+	if (!progs)
+		return -EOPNOTSUPP;
+
+	switch (which) {
+	case BPF_SK_MSG_VERDICT:
+		psock_set_prog(&progs->msg_parser, prog);
+		break;
+	case BPF_SK_SKB_STREAM_PARSER:
+		psock_set_prog(&progs->skb_parser, prog);
+		break;
+	case BPF_SK_SKB_STREAM_VERDICT:
+		psock_set_prog(&progs->skb_verdict, prog);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+void sk_psock_unlink(struct sock *sk, struct sk_psock_link *link)
+{
+	switch (link->map->map_type) {
+	case BPF_MAP_TYPE_SOCKMAP:
+		return sock_map_delete_from_link(link->map, sk,
+						 link->link_raw);
+	case BPF_MAP_TYPE_SOCKHASH:
+		return sock_hash_delete_from_link(link->map, sk,
+						  link->link_raw);
+	default:
+		break;
+	}
+}