bpf: sockmap, add sock close() hook to remove socks
The selftests test_maps program was leaving dangling BPF sockmap
programs around because not all psock elements were removed from
the map. The elements in turn hold a reference on the BPF program
they are attached to causing BPF programs to stay open even after
test_maps has completed.
The original intent was that sk_state_change() would be called
when TCP socks went through TCP_CLOSE state. However, because
socks may be in SOCK_DEAD state or the sock may be a listening
socket the event is not always triggered.
To resolve this use the ULP infrastructure and register our own
proto close() handler. This fixes the above case.
Fixes: 174a79ff95 ("bpf: sockmap with sk redirect support")
Reported-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
John Fastabend
Daniel Borkmann
Родитель
b11a632c44
Коммит
1aa12bdf1b
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@ -1985,6 +1985,7 @@ enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
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enum {
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TCP_ULP_TLS,
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TCP_ULP_BPF,
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};
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struct tcp_ulp_ops {
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@ -2003,6 +2004,7 @@ struct tcp_ulp_ops {
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int tcp_register_ulp(struct tcp_ulp_ops *type);
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void tcp_unregister_ulp(struct tcp_ulp_ops *type);
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int tcp_set_ulp(struct sock *sk, const char *name);
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int tcp_set_ulp_id(struct sock *sk, const int ulp);
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void tcp_get_available_ulp(char *buf, size_t len);
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void tcp_cleanup_ulp(struct sock *sk);
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@ -86,9 +86,10 @@ struct smap_psock {
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struct work_struct tx_work;
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struct work_struct gc_work;
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struct proto *sk_proto;
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void (*save_close)(struct sock *sk, long timeout);
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void (*save_data_ready)(struct sock *sk);
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void (*save_write_space)(struct sock *sk);
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void (*save_state_change)(struct sock *sk);
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};
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static inline struct smap_psock *smap_psock_sk(const struct sock *sk)
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@ -96,12 +97,102 @@ static inline struct smap_psock *smap_psock_sk(const struct sock *sk)
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return rcu_dereference_sk_user_data(sk);
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}
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static struct proto tcp_bpf_proto;
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static int bpf_tcp_init(struct sock *sk)
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{
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struct smap_psock *psock;
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rcu_read_lock();
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psock = smap_psock_sk(sk);
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if (unlikely(!psock)) {
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rcu_read_unlock();
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return -EINVAL;
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}
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if (unlikely(psock->sk_proto)) {
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rcu_read_unlock();
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return -EBUSY;
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}
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psock->save_close = sk->sk_prot->close;
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psock->sk_proto = sk->sk_prot;
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sk->sk_prot = &tcp_bpf_proto;
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rcu_read_unlock();
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return 0;
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}
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static void bpf_tcp_release(struct sock *sk)
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{
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struct smap_psock *psock;
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rcu_read_lock();
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psock = smap_psock_sk(sk);
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if (likely(psock)) {
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sk->sk_prot = psock->sk_proto;
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psock->sk_proto = NULL;
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}
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rcu_read_unlock();
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}
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static void smap_release_sock(struct smap_psock *psock, struct sock *sock);
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static void bpf_tcp_close(struct sock *sk, long timeout)
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{
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void (*close_fun)(struct sock *sk, long timeout);
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struct smap_psock_map_entry *e, *tmp;
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struct smap_psock *psock;
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struct sock *osk;
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rcu_read_lock();
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psock = smap_psock_sk(sk);
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if (unlikely(!psock)) {
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rcu_read_unlock();
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return sk->sk_prot->close(sk, timeout);
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}
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/* The psock may be destroyed anytime after exiting the RCU critial
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* section so by the time we use close_fun the psock may no longer
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* be valid. However, bpf_tcp_close is called with the sock lock
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* held so the close hook and sk are still valid.
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*/
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close_fun = psock->save_close;
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write_lock_bh(&sk->sk_callback_lock);
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list_for_each_entry_safe(e, tmp, &psock->maps, list) {
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osk = cmpxchg(e->entry, sk, NULL);
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if (osk == sk) {
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list_del(&e->list);
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smap_release_sock(psock, sk);
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}
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}
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write_unlock_bh(&sk->sk_callback_lock);
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rcu_read_unlock();
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close_fun(sk, timeout);
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}
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enum __sk_action {
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__SK_DROP = 0,
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__SK_PASS,
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__SK_REDIRECT,
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};
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static struct tcp_ulp_ops bpf_tcp_ulp_ops __read_mostly = {
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.name = "bpf_tcp",
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.uid = TCP_ULP_BPF,
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.user_visible = false,
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.owner = NULL,
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.init = bpf_tcp_init,
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.release = bpf_tcp_release,
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};
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static int bpf_tcp_ulp_register(void)
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{
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tcp_bpf_proto = tcp_prot;
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tcp_bpf_proto.close = bpf_tcp_close;
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return tcp_register_ulp(&bpf_tcp_ulp_ops);
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}
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static int smap_verdict_func(struct smap_psock *psock, struct sk_buff *skb)
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{
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struct bpf_prog *prog = READ_ONCE(psock->bpf_verdict);
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@ -166,68 +257,6 @@ static void smap_report_sk_error(struct smap_psock *psock, int err)
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sk->sk_error_report(sk);
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}
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static void smap_release_sock(struct smap_psock *psock, struct sock *sock);
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/* Called with lock_sock(sk) held */
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static void smap_state_change(struct sock *sk)
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{
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struct smap_psock_map_entry *e, *tmp;
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struct smap_psock *psock;
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struct socket_wq *wq;
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struct sock *osk;
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rcu_read_lock();
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/* Allowing transitions into an established syn_recv states allows
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* for early binding sockets to a smap object before the connection
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* is established.
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*/
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switch (sk->sk_state) {
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case TCP_SYN_SENT:
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case TCP_SYN_RECV:
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case TCP_ESTABLISHED:
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break;
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case TCP_CLOSE_WAIT:
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case TCP_CLOSING:
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case TCP_LAST_ACK:
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case TCP_FIN_WAIT1:
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case TCP_FIN_WAIT2:
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case TCP_LISTEN:
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break;
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case TCP_CLOSE:
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/* Only release if the map entry is in fact the sock in
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* question. There is a case where the operator deletes
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* the sock from the map, but the TCP sock is closed before
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* the psock is detached. Use cmpxchg to verify correct
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* sock is removed.
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*/
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psock = smap_psock_sk(sk);
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if (unlikely(!psock))
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break;
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write_lock_bh(&sk->sk_callback_lock);
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list_for_each_entry_safe(e, tmp, &psock->maps, list) {
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osk = cmpxchg(e->entry, sk, NULL);
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if (osk == sk) {
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list_del(&e->list);
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smap_release_sock(psock, sk);
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}
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}
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write_unlock_bh(&sk->sk_callback_lock);
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break;
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default:
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psock = smap_psock_sk(sk);
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if (unlikely(!psock))
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break;
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smap_report_sk_error(psock, EPIPE);
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break;
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}
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wq = rcu_dereference(sk->sk_wq);
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if (skwq_has_sleeper(wq))
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wake_up_interruptible_all(&wq->wait);
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rcu_read_unlock();
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}
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static void smap_read_sock_strparser(struct strparser *strp,
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struct sk_buff *skb)
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{
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@ -322,10 +351,8 @@ static void smap_stop_sock(struct smap_psock *psock, struct sock *sk)
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return;
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sk->sk_data_ready = psock->save_data_ready;
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sk->sk_write_space = psock->save_write_space;
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sk->sk_state_change = psock->save_state_change;
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psock->save_data_ready = NULL;
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psock->save_write_space = NULL;
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psock->save_state_change = NULL;
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strp_stop(&psock->strp);
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psock->strp_enabled = false;
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}
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@ -350,6 +377,7 @@ static void smap_release_sock(struct smap_psock *psock, struct sock *sock)
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if (psock->refcnt)
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return;
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tcp_cleanup_ulp(sock);
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smap_stop_sock(psock, sock);
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clear_bit(SMAP_TX_RUNNING, &psock->state);
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rcu_assign_sk_user_data(sock, NULL);
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@ -427,10 +455,8 @@ static void smap_start_sock(struct smap_psock *psock, struct sock *sk)
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return;
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psock->save_data_ready = sk->sk_data_ready;
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psock->save_write_space = sk->sk_write_space;
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psock->save_state_change = sk->sk_state_change;
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sk->sk_data_ready = smap_data_ready;
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sk->sk_write_space = smap_write_space;
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sk->sk_state_change = smap_state_change;
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psock->strp_enabled = true;
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}
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@ -509,6 +535,10 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
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if (attr->value_size > KMALLOC_MAX_SIZE)
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return ERR_PTR(-E2BIG);
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err = bpf_tcp_ulp_register();
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if (err && err != -EEXIST)
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return ERR_PTR(err);
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stab = kzalloc(sizeof(*stab), GFP_USER);
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if (!stab)
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return ERR_PTR(-ENOMEM);
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@ -754,6 +784,10 @@ static int sock_map_ctx_update_elem(struct bpf_sock_ops_kern *skops,
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goto out_progs;
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}
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err = tcp_set_ulp_id(sock, TCP_ULP_BPF);
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if (err)
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goto out_progs;
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set_bit(SMAP_TX_RUNNING, &psock->state);
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}
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