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mptcp: full disconnect implementation
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The current mptcp_disconnect() implementation lacks several
steps, we additionally need to reset the msk socket state
and flush the subflow list.

Factor out the needed helper to avoid code duplication.

Additionally ensure that the initial subflow is disposed
only after mptcp_close(), just reset it at disconnect time.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Paolo Abeni authored and David S. Miller committed Jan 7, 2022
1 parent f284c0c commit b29fcfb
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Showing 4 changed files with 98 additions and 28 deletions.
10 changes: 7 additions & 3 deletions net/mptcp/pm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -356,7 +356,7 @@ void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
}
}

void mptcp_pm_data_init(struct mptcp_sock *msk)
void mptcp_pm_data_reset(struct mptcp_sock *msk)
{
msk->pm.add_addr_signaled = 0;
msk->pm.add_addr_accepted = 0;
Expand All @@ -371,10 +371,14 @@ void mptcp_pm_data_init(struct mptcp_sock *msk)
WRITE_ONCE(msk->pm.remote_deny_join_id0, false);
msk->pm.status = 0;

mptcp_pm_nl_data_init(msk);
}

void mptcp_pm_data_init(struct mptcp_sock *msk)
{
spin_lock_init(&msk->pm.lock);
INIT_LIST_HEAD(&msk->pm.anno_list);

mptcp_pm_nl_data_init(msk);
mptcp_pm_data_reset(msk);
}

void __init mptcp_pm_init(void)
Expand Down
101 changes: 76 additions & 25 deletions net/mptcp/protocol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2253,6 +2253,10 @@ bool __mptcp_retransmit_pending_data(struct sock *sk)
return true;
}

/* flags for __mptcp_close_ssk() */
#define MPTCP_CF_PUSH BIT(1)
#define MPTCP_CF_FASTCLOSE BIT(2)

/* subflow sockets can be either outgoing (connect) or incoming
* (accept).
*
Expand All @@ -2262,22 +2266,37 @@ bool __mptcp_retransmit_pending_data(struct sock *sk)
* parent socket.
*/
static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
struct mptcp_subflow_context *subflow)
struct mptcp_subflow_context *subflow,
unsigned int flags)
{
struct mptcp_sock *msk = mptcp_sk(sk);
bool need_push;
bool need_push, dispose_it;

list_del(&subflow->node);
dispose_it = !msk->subflow || ssk != msk->subflow->sk;
if (dispose_it)
list_del(&subflow->node);

lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);

if (flags & MPTCP_CF_FASTCLOSE)
subflow->send_fastclose = 1;

need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
if (!dispose_it) {
tcp_disconnect(ssk, 0);
msk->subflow->state = SS_UNCONNECTED;
mptcp_subflow_ctx_reset(subflow);
release_sock(ssk);

goto out;
}

/* if we are invoked by the msk cleanup code, the subflow is
* already orphaned
*/
if (ssk->sk_socket)
sock_orphan(ssk);

need_push = __mptcp_retransmit_pending_data(sk);
subflow->disposable = 1;

/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
Expand All @@ -2297,14 +2316,12 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,

sock_put(ssk);

if (ssk == msk->last_snd)
msk->last_snd = NULL;

if (ssk == msk->first)
msk->first = NULL;

if (msk->subflow && ssk == msk->subflow->sk)
mptcp_dispose_initial_subflow(msk);
out:
if (ssk == msk->last_snd)
msk->last_snd = NULL;

if (need_push)
__mptcp_push_pending(sk, 0);
Expand All @@ -2315,7 +2332,7 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
{
if (sk->sk_state == TCP_ESTABLISHED)
mptcp_event(MPTCP_EVENT_SUB_CLOSED, mptcp_sk(sk), ssk, GFP_KERNEL);
__mptcp_close_ssk(sk, ssk, subflow);
__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_PUSH);
}

static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
Expand Down Expand Up @@ -2533,9 +2550,20 @@ static int __mptcp_init_sock(struct sock *sk)
return 0;
}

static int mptcp_init_sock(struct sock *sk)
static void mptcp_ca_reset(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);

tcp_assign_congestion_control(sk);
strcpy(mptcp_sk(sk)->ca_name, icsk->icsk_ca_ops->name);

/* no need to keep a reference to the ops, the name will suffice */
tcp_cleanup_congestion_control(sk);
icsk->icsk_ca_ops = NULL;
}

static int mptcp_init_sock(struct sock *sk)
{
struct net *net = sock_net(sk);
int ret;

Expand All @@ -2556,12 +2584,7 @@ static int mptcp_init_sock(struct sock *sk)
/* fetch the ca name; do it outside __mptcp_init_sock(), so that clone will
* propagate the correct value
*/
tcp_assign_congestion_control(sk);
strcpy(mptcp_sk(sk)->ca_name, icsk->icsk_ca_ops->name);

/* no need to keep a reference to the ops, the name will suffice */
tcp_cleanup_congestion_control(sk);
icsk->icsk_ca_ops = NULL;
mptcp_ca_reset(sk);

sk_sockets_allocated_inc(sk);
sk->sk_rcvbuf = sock_net(sk)->ipv4.sysctl_tcp_rmem[1];
Expand Down Expand Up @@ -2720,9 +2743,13 @@ static void __mptcp_destroy_sock(struct sock *sk)
sk_stop_timer(sk, &sk->sk_timer);
msk->pm.status = 0;

/* clears msk->subflow, allowing the following loop to close
* even the initial subflow
*/
mptcp_dispose_initial_subflow(msk);
list_for_each_entry_safe(subflow, tmp, &conn_list, node) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
__mptcp_close_ssk(sk, ssk, subflow);
__mptcp_close_ssk(sk, ssk, subflow, 0);
}

sk->sk_prot->destroy(sk);
Expand All @@ -2733,7 +2760,6 @@ static void __mptcp_destroy_sock(struct sock *sk)
xfrm_sk_free_policy(sk);

sk_refcnt_debug_release(sk);
mptcp_dispose_initial_subflow(msk);
sock_put(sk);
}

Expand Down Expand Up @@ -2769,6 +2795,9 @@ static void mptcp_close(struct sock *sk, long timeout)

sock_hold(sk);
pr_debug("msk=%p state=%d", sk, sk->sk_state);
if (mptcp_sk(sk)->token)
mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);

if (sk->sk_state == TCP_CLOSE) {
__mptcp_destroy_sock(sk);
do_cancel_work = true;
Expand All @@ -2779,9 +2808,6 @@ static void mptcp_close(struct sock *sk, long timeout)
if (do_cancel_work)
mptcp_cancel_work(sk);

if (mptcp_sk(sk)->token)
mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);

sock_put(sk);
}

Expand Down Expand Up @@ -2815,13 +2841,36 @@ static int mptcp_disconnect(struct sock *sk, int flags)

mptcp_do_flush_join_list(msk);

inet_sk_state_store(sk, TCP_CLOSE);

mptcp_for_each_subflow(msk, subflow) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);

lock_sock(ssk);
tcp_disconnect(ssk, flags);
release_sock(ssk);
__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_FASTCLOSE);
}

sk_stop_timer(sk, &msk->sk.icsk_retransmit_timer);
sk_stop_timer(sk, &sk->sk_timer);

if (mptcp_sk(sk)->token)
mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);

mptcp_destroy_common(msk);
msk->last_snd = NULL;
msk->flags = 0;
msk->recovery = false;
msk->can_ack = false;
msk->fully_established = false;
msk->rcv_data_fin = false;
msk->snd_data_fin_enable = false;
msk->rcv_fastclose = false;
msk->use_64bit_ack = false;
WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk)));
mptcp_pm_data_reset(msk);
mptcp_ca_reset(sk);

sk->sk_shutdown = 0;
sk_error_report(sk);
return 0;
}

Expand Down Expand Up @@ -2961,9 +3010,11 @@ void mptcp_destroy_common(struct mptcp_sock *msk)
__mptcp_clear_xmit(sk);

/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
mptcp_data_lock(sk);
skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
__skb_queue_purge(&sk->sk_receive_queue);
skb_rbtree_purge(&msk->out_of_order_queue);
mptcp_data_unlock(sk);

/* move all the rx fwd alloc into the sk_mem_reclaim_final in
* inet_sock_destruct() will dispose it
Expand Down
14 changes: 14 additions & 0 deletions net/mptcp/protocol.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -395,6 +395,9 @@ DECLARE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
/* MPTCP subflow context */
struct mptcp_subflow_context {
struct list_head node;/* conn_list of subflows */

char reset_start[0];

unsigned long avg_pacing_rate; /* protected by msk socket lock */
u64 local_key;
u64 remote_key;
Expand Down Expand Up @@ -442,6 +445,9 @@ struct mptcp_subflow_context {
u8 stale_count;

long delegated_status;

char reset_end[0];

struct list_head delegated_node; /* link into delegated_action, protected by local BH */

u32 setsockopt_seq;
Expand Down Expand Up @@ -473,6 +479,13 @@ mptcp_subflow_tcp_sock(const struct mptcp_subflow_context *subflow)
return subflow->tcp_sock;
}

static inline void
mptcp_subflow_ctx_reset(struct mptcp_subflow_context *subflow)
{
memset(subflow->reset_start, 0, subflow->reset_end - subflow->reset_start);
subflow->request_mptcp = 1;
}

static inline u64
mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
{
Expand Down Expand Up @@ -713,6 +726,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac);

void __init mptcp_pm_init(void);
void mptcp_pm_data_init(struct mptcp_sock *msk);
void mptcp_pm_data_reset(struct mptcp_sock *msk);
void mptcp_pm_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk);
void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk);
void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side);
Expand Down
1 change: 1 addition & 0 deletions net/mptcp/token.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -384,6 +384,7 @@ void mptcp_token_destroy(struct mptcp_sock *msk)
bucket->chain_len--;
}
spin_unlock_bh(&bucket->lock);
WRITE_ONCE(msk->token, 0);
}

void __init mptcp_token_init(void)
Expand Down

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