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mptcp: create msk early
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This change moves the mptcp socket allocation from mptcp_accept() to
subflow_syn_recv_sock(), so that subflow->conn is now always set
for the non fallback scenario.

It allows cleaning up a bit mptcp_accept() reducing the additional
locking and will allow fourther cleanup in the next patch.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@davem330
Paolo Abeni authored and davem330 committed Mar 15, 2020
1 parent 7a1d0e6 commit 58b0991
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Showing 4 changed files with 70 additions and 80 deletions.
83 changes: 45 additions & 38 deletions net/mptcp/protocol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -820,9 +820,12 @@ static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
}
#endif

static struct sock *mptcp_sk_clone_lock(const struct sock *sk)
struct sock *mptcp_sk_clone(const struct sock *sk, struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
struct mptcp_sock *msk;
u64 ack_seq;

if (!nsk)
return NULL;
Expand All @@ -832,6 +835,36 @@ static struct sock *mptcp_sk_clone_lock(const struct sock *sk)
inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk);
#endif

__mptcp_init_sock(nsk);

msk = mptcp_sk(nsk);
msk->local_key = subflow_req->local_key;
msk->token = subflow_req->token;
msk->subflow = NULL;

if (unlikely(mptcp_token_new_accept(subflow_req->token, nsk))) {
bh_unlock_sock(nsk);

/* we can't call into mptcp_close() here - possible BH context
* free the sock directly
*/
nsk->sk_prot->destroy(nsk);
sk_free(nsk);
return NULL;
}

msk->write_seq = subflow_req->idsn + 1;
if (subflow_req->remote_key_valid) {
msk->can_ack = true;
msk->remote_key = subflow_req->remote_key;
mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
ack_seq++;
msk->ack_seq = ack_seq;
}
bh_unlock_sock(nsk);

/* keep a single reference */
__sock_put(nsk);
return nsk;
}

Expand Down Expand Up @@ -859,40 +892,26 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
struct mptcp_subflow_context *subflow;
struct sock *new_mptcp_sock;
struct sock *ssk = newsk;
u64 ack_seq;

subflow = mptcp_subflow_ctx(newsk);
lock_sock(sk);
new_mptcp_sock = subflow->conn;

local_bh_disable();
new_mptcp_sock = mptcp_sk_clone_lock(sk);
if (!new_mptcp_sock) {
*err = -ENOBUFS;
local_bh_enable();
release_sock(sk);
mptcp_subflow_shutdown(newsk, SHUT_RDWR + 1, 0, 0);
tcp_close(newsk, 0);
return NULL;
/* is_mptcp should be false if subflow->conn is missing, see
* subflow_syn_recv_sock()
*/
if (WARN_ON_ONCE(!new_mptcp_sock)) {
tcp_sk(newsk)->is_mptcp = 0;
return newsk;
}

__mptcp_init_sock(new_mptcp_sock);
/* acquire the 2nd reference for the owning socket */
sock_hold(new_mptcp_sock);

local_bh_disable();
bh_lock_sock(new_mptcp_sock);
msk = mptcp_sk(new_mptcp_sock);
msk->local_key = subflow->local_key;
msk->token = subflow->token;
msk->subflow = NULL;
msk->first = newsk;

mptcp_token_update_accept(newsk, new_mptcp_sock);

msk->write_seq = subflow->idsn + 1;
if (subflow->can_ack) {
msk->can_ack = true;
msk->remote_key = subflow->remote_key;
mptcp_crypto_key_sha(msk->remote_key, NULL, &ack_seq);
ack_seq++;
msk->ack_seq = ack_seq;
}
newsk = new_mptcp_sock;
mptcp_copy_inaddrs(newsk, ssk);
list_add(&subflow->node, &msk->conn_list);
Expand All @@ -903,18 +922,6 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
inet_sk_state_store(new_mptcp_sock, TCP_SYN_RECV);
bh_unlock_sock(new_mptcp_sock);
local_bh_enable();
release_sock(sk);

/* the subflow can already receive packet, avoid racing with
* the receive path and process the pending ones
*/
lock_sock(ssk);
subflow->rel_write_seq = 1;
subflow->tcp_sock = ssk;
subflow->conn = new_mptcp_sock;
if (unlikely(!skb_queue_empty(&ssk->sk_receive_queue)))
mptcp_subflow_data_available(ssk);
release_sock(ssk);
}

return newsk;
Expand Down
4 changes: 2 additions & 2 deletions net/mptcp/protocol.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,7 @@ void mptcp_proto_init(void);
int mptcp_proto_v6_init(void);
#endif

struct sock *mptcp_sk_clone(const struct sock *sk, struct request_sock *req);
void mptcp_get_options(const struct sk_buff *skb,
struct tcp_options_received *opt_rx);

Expand All @@ -202,8 +203,7 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk);
int mptcp_token_new_request(struct request_sock *req);
void mptcp_token_destroy_request(u32 token);
int mptcp_token_new_connect(struct sock *sk);
int mptcp_token_new_accept(u32 token);
void mptcp_token_update_accept(struct sock *sk, struct sock *conn);
int mptcp_token_new_accept(u32 token, struct sock *conn);
void mptcp_token_destroy(u32 token);

void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn);
Expand Down
32 changes: 21 additions & 11 deletions net/mptcp/subflow.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -182,6 +182,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
struct mptcp_subflow_request_sock *subflow_req;
struct tcp_options_received opt_rx;
struct sock *new_msk = NULL;
struct sock *child;

pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
Expand All @@ -197,7 +198,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
* out-of-order pkt, which will not carry the MP_CAPABLE
* opt even on mptcp enabled paths
*/
goto create_child;
goto create_msk;
}

opt_rx.mptcp.mp_capable = 0;
Expand All @@ -207,7 +208,13 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
subflow_req->remote_key_valid = 1;
} else {
subflow_req->mp_capable = 0;
goto create_child;
}

create_msk:
new_msk = mptcp_sk_clone(listener->conn, req);
if (!new_msk)
subflow_req->mp_capable = 0;
}

create_child:
Expand All @@ -221,22 +228,22 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
* handshake
*/
if (!ctx)
return child;
goto out;

if (ctx->mp_capable) {
if (mptcp_token_new_accept(ctx->token))
goto close_child;
/* new mpc subflow takes ownership of the newly
* created mptcp socket
*/
ctx->conn = new_msk;
new_msk = NULL;
}
}

out:
/* dispose of the left over mptcp master, if any */
if (unlikely(new_msk))
sock_put(new_msk);
return child;

close_child:
pr_debug("closing child socket");
tcp_send_active_reset(child, GFP_ATOMIC);
inet_csk_prepare_forced_close(child);
tcp_done(child);
return NULL;
}

static struct inet_connection_sock_af_ops subflow_specific;
Expand Down Expand Up @@ -793,6 +800,9 @@ static void subflow_ulp_clone(const struct request_sock *req,
new_ctx->tcp_data_ready = old_ctx->tcp_data_ready;
new_ctx->tcp_state_change = old_ctx->tcp_state_change;
new_ctx->tcp_write_space = old_ctx->tcp_write_space;
new_ctx->rel_write_seq = 1;
new_ctx->tcp_sock = newsk;

new_ctx->mp_capable = 1;
new_ctx->fourth_ack = subflow_req->remote_key_valid;
new_ctx->can_ack = subflow_req->remote_key_valid;
Expand Down
31 changes: 2 additions & 29 deletions net/mptcp/token.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -128,45 +128,18 @@ int mptcp_token_new_connect(struct sock *sk)
*
* Called when a SYN packet creates a new logical connection, i.e.
* is not a join request.
*
* We don't have an mptcp socket yet at that point.
* This is paired with mptcp_token_update_accept, called on accept().
*/
int mptcp_token_new_accept(u32 token)
int mptcp_token_new_accept(u32 token, struct sock *conn)
{
int err;

spin_lock_bh(&token_tree_lock);
err = radix_tree_insert(&token_tree, token, &token_used);
err = radix_tree_insert(&token_tree, token, conn);
spin_unlock_bh(&token_tree_lock);

return err;
}

/**
* mptcp_token_update_accept - update token to map to mptcp socket
* @conn: the new struct mptcp_sock
* @sk: the initial subflow for this mptcp socket
*
* Called when the first mptcp socket is created on accept to
* refresh the dummy mapping (done to reserve the token) with
* the mptcp_socket structure that wasn't allocated before.
*/
void mptcp_token_update_accept(struct sock *sk, struct sock *conn)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
void __rcu **slot;

spin_lock_bh(&token_tree_lock);
slot = radix_tree_lookup_slot(&token_tree, subflow->token);
WARN_ON_ONCE(!slot);
if (slot) {
WARN_ON_ONCE(rcu_access_pointer(*slot) != &token_used);
radix_tree_replace_slot(&token_tree, slot, conn);
}
spin_unlock_bh(&token_tree_lock);
}

/**
* mptcp_token_destroy_request - remove mptcp connection/token
* @token - token of mptcp connection to remove
Expand Down

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