From dc87efdb1a5cd46134a9d490480160e303bc6eef Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 1 Apr 2021 16:19:44 -0700 Subject: mptcp: add mptcp reset option support The MPTCP reset option allows to carry a mptcp-specific error code that provides more information on the nature of a connection reset. Reset option data received gets stored in the subflow context so it can be sent to userspace via the 'subflow closed' netlink event. When a subflow is closed, the desired error code that should be sent to the peer is also placed in the subflow context structure. If a reset is sent before subflow establishment could complete, e.g. on HMAC failure during an MP_JOIN operation, the mptcp skb extension is used to store the reset information. Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/subflow.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) (limited to 'net/mptcp/subflow.c') diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 7a5f50d00d4b..223d6be5fc3b 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -115,6 +115,16 @@ static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct soc return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport; } +static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) +{ + struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP); + + if (mpext) { + memset(mpext, 0, sizeof(*mpext)); + mpext->reset_reason = reason; + } +} + /* Init mptcp request socket. * * Returns an error code if a JOIN has failed and a TCP reset @@ -190,8 +200,10 @@ again: subflow_req->msk = subflow_token_join_request(req); /* Can't fall back to TCP in this case. */ - if (!subflow_req->msk) + if (!subflow_req->msk) { + subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); return -EPERM; + } if (subflow_use_different_sport(subflow_req->msk, sk_listener)) { pr_debug("syn inet_sport=%d %d", @@ -400,8 +412,10 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) } else if (subflow->request_join) { u8 hmac[SHA256_DIGEST_SIZE]; - if (!mp_opt.mp_join) + if (!mp_opt.mp_join) { + subflow->reset_reason = MPTCP_RST_EMPTCP; goto do_reset; + } subflow->thmac = mp_opt.thmac; subflow->remote_nonce = mp_opt.nonce; @@ -410,6 +424,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb) if (!subflow_thmac_valid(subflow)) { MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC); + subflow->reset_reason = MPTCP_RST_EMPTCP; goto do_reset; } @@ -438,6 +453,7 @@ fallback: return; do_reset: + subflow->reset_transient = 0; mptcp_subflow_reset(sk); } @@ -654,8 +670,10 @@ create_child: * to reset the context to non MPTCP status. */ if (!ctx || fallback) { - if (fallback_is_fatal) + if (fallback_is_fatal) { + subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP); goto dispose_child; + } subflow_drop_ctx(child); goto out; @@ -690,8 +708,10 @@ create_child: struct mptcp_sock *owner; owner = subflow_req->msk; - if (!owner) + if (!owner) { + subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); goto dispose_child; + } /* move the msk reference ownership to the subflow */ subflow_req->msk = NULL; @@ -1056,6 +1076,8 @@ fatal: smp_wmb(); ssk->sk_error_report(ssk); tcp_set_state(ssk, TCP_CLOSE); + subflow->reset_transient = 0; + subflow->reset_reason = MPTCP_RST_EMPTCP; tcp_send_active_reset(ssk, GFP_ATOMIC); subflow->data_avail = 0; return false; -- cgit v1.2.3