#include <net/request_sock.h>
-/*
- * This function is called to set a Fast Open socket's "fastopen_rsk" field
- * to NULL when a TFO socket no longer needs to access the request_sock.
- * This happens only after 3WHS has been either completed or aborted (e.g.,
- * RST is received).
- *
- * Before TFO, a child socket is created only after 3WHS is completed,
- * hence it never needs to access the request_sock. things get a lot more
- * complex with TFO. A child socket, accepted or not, has to access its
- * request_sock for 3WHS processing, e.g., to retransmit SYN-ACK pkts,
- * until 3WHS is either completed or aborted. Afterwards the req will stay
- * until either the child socket is accepted, or in the rare case when the
- * listener is closed before the child is accepted.
- *
- * In short, a request socket is only freed after BOTH 3WHS has completed
- * (or aborted) and the child socket has been accepted (or listener closed).
- * When a child socket is accepted, its corresponding req->sk is set to
- * NULL since it's no longer needed. More importantly, "req->sk == NULL"
- * will be used by the code below to determine if a child socket has been
- * accepted or not, and the check is protected by the fastopenq->lock
- * described below.
- *
- * Note that fastopen_rsk is only accessed from the child socket's context
- * with its socket lock held. But a request_sock (req) can be accessed by
- * both its child socket through fastopen_rsk, and a listener socket through
- * icsk_accept_queue.rskq_accept_head. To protect the access a simple spin
- * lock per listener "icsk->icsk_accept_queue.fastopenq->lock" is created.
- * only in the rare case when both the listener and the child locks are held,
- * e.g., in inet_csk_listen_stop() do we not need to acquire the lock.
- * The lock also protects other fields such as fastopenq->qlen, which is
- * decremented by this function when fastopen_rsk is no longer needed.
- *
- * Note that another solution was to simply use the existing socket lock
- * from the listener. But first socket lock is difficult to use. It is not
- * a simple spin lock - one must consider sock_owned_by_user() and arrange
- * to use sk_add_backlog() stuff. But what really makes it infeasible is the
- * locking hierarchy violation. E.g., inet_csk_listen_stop() may try to
- * acquire a child's lock while holding listener's socket lock.
- *
- * This function also sets "treq->tfo_listener" to false.
- * treq->tfo_listener is used by the listener so it is protected by the
- * fastopenq->lock in this function.
- */
-void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
- bool reset)
-{
- struct sock *lsk = req->rsk_listener;
- struct fastopen_queue *fastopenq;
-
- fastopenq = &inet_csk(lsk)->icsk_accept_queue.fastopenq;
-
- RCU_INIT_POINTER(tcp_sk(sk)->fastopen_rsk, NULL);
- spin_lock_bh(&fastopenq->lock);
- fastopenq->qlen--;
- tcp_rsk(req)->tfo_listener = false;
- if (req->sk) /* the child socket hasn't been accepted yet */
- goto out;
-
- if (!reset || lsk->sk_state != TCP_LISTEN) {
- /* If the listener has been closed don't bother with the
- * special RST handling below.
- */
- spin_unlock_bh(&fastopenq->lock);
- reqsk_put(req);
- return;
- }
- /* Wait for 60secs before removing a req that has triggered RST.
- * This is a simple defense against TFO spoofing attack - by
- * counting the req against fastopen.max_qlen, and disabling
- * TFO when the qlen exceeds max_qlen.
- *
- * For more details see CoNext'11 "TCP Fast Open" paper.
- */
- req->rsk_timer.expires = jiffies + 60*HZ;
- if (fastopenq->rskq_rst_head == NULL)
- fastopenq->rskq_rst_head = req;
- else
- fastopenq->rskq_rst_tail->dl_next = req;
-
- req->dl_next = NULL;
- fastopenq->rskq_rst_tail = req;
- fastopenq->qlen++;
-out:
- spin_unlock_bh(&fastopenq->lock);
-}
#include <net/tcp.h>
#include <net/busy_poll.h>
+/*
+ * This function is called to set a Fast Open socket's "fastopen_rsk" field
+ * to NULL when a TFO socket no longer needs to access the request_sock.
+ * This happens only after 3WHS has been either completed or aborted (e.g.,
+ * RST is received).
+ *
+ * Before TFO, a child socket is created only after 3WHS is completed,
+ * hence it never needs to access the request_sock. things get a lot more
+ * complex with TFO. A child socket, accepted or not, has to access its
+ * request_sock for 3WHS processing, e.g., to retransmit SYN-ACK pkts,
+ * until 3WHS is either completed or aborted. Afterwards the req will stay
+ * until either the child socket is accepted, or in the rare case when the
+ * listener is closed before the child is accepted.
+ *
+ * In short, a request socket is only freed after BOTH 3WHS has completed
+ * (or aborted) and the child socket has been accepted (or listener closed).
+ * When a child socket is accepted, its corresponding req->sk is set to
+ * NULL since it's no longer needed. More importantly, "req->sk == NULL"
+ * will be used by the code below to determine if a child socket has been
+ * accepted or not, and the check is protected by the fastopenq->lock
+ * described below.
+ *
+ * Note that fastopen_rsk is only accessed from the child socket's context
+ * with its socket lock held. But a request_sock (req) can be accessed by
+ * both its child socket through fastopen_rsk, and a listener socket through
+ * icsk_accept_queue.rskq_accept_head. To protect the access a simple spin
+ * lock per listener "icsk->icsk_accept_queue.fastopenq->lock" is created.
+ * only in the rare case when both the listener and the child locks are held,
+ * e.g., in inet_csk_listen_stop() do we not need to acquire the lock.
+ * The lock also protects other fields such as fastopenq->qlen, which is
+ * decremented by this function when fastopen_rsk is no longer needed.
+ *
+ * Note that another solution was to simply use the existing socket lock
+ * from the listener. But first socket lock is difficult to use. It is not
+ * a simple spin lock - one must consider sock_owned_by_user() and arrange
+ * to use sk_add_backlog() stuff. But what really makes it infeasible is the
+ * locking hierarchy violation. E.g., inet_csk_listen_stop() may try to
+ * acquire a child's lock while holding listener's socket lock.
+ *
+ * This function also sets "treq->tfo_listener" to false.
+ * treq->tfo_listener is used by the listener so it is protected by the
+ * fastopenq->lock in this function.
+ */
+void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
+ bool reset)
+{
+ struct sock *lsk = req->rsk_listener;
+ struct fastopen_queue *fastopenq;
+
+ fastopenq = &inet_csk(lsk)->icsk_accept_queue.fastopenq;
+
+ RCU_INIT_POINTER(tcp_sk(sk)->fastopen_rsk, NULL);
+ spin_lock_bh(&fastopenq->lock);
+ fastopenq->qlen--;
+ tcp_rsk(req)->tfo_listener = false;
+ if (req->sk) /* the child socket hasn't been accepted yet */
+ goto out;
+
+ if (!reset || lsk->sk_state != TCP_LISTEN) {
+ /* If the listener has been closed don't bother with the
+ * special RST handling below.
+ */
+ spin_unlock_bh(&fastopenq->lock);
+ reqsk_put(req);
+ return;
+ }
+ /* Wait for 60secs before removing a req that has triggered RST.
+ * This is a simple defense against TFO spoofing attack - by
+ * counting the req against fastopen.max_qlen, and disabling
+ * TFO when the qlen exceeds max_qlen.
+ *
+ * For more details see CoNext'11 "TCP Fast Open" paper.
+ */
+ req->rsk_timer.expires = jiffies + 60*HZ;
+ if (fastopenq->rskq_rst_head == NULL)
+ fastopenq->rskq_rst_head = req;
+ else
+ fastopenq->rskq_rst_tail->dl_next = req;
+
+ req->dl_next = NULL;
+ fastopenq->rskq_rst_tail = req;
+ fastopenq->qlen++;
+out:
+ spin_unlock_bh(&fastopenq->lock);
+}
+
void tcp_fastopen_init_key_once(struct net *net)
{
u8 key[TCP_FASTOPEN_KEY_LENGTH];
projects / thirdparty / kernel / linux.git / commitdiff
