From c94b1f96dcfb2e5bd072b10f3429ccf28778ad58 Mon Sep 17 00:00:00 2001 From: Geliang Tang Date: Thu, 17 Jun 2021 16:46:10 -0700 Subject: [PATCH] mptcp: send out checksum for MP_CAPABLE with data If the checksum is enabled, send out the data checksum with the MP_CAPABLE suboption with data. In mptcp_established_options_mp, save the data checksum in opts->ext_copy.csum. In mptcp_write_options, adjust the option length and send it out with the MP_CAPABLE suboption. Co-developed-by: Paolo Abeni Signed-off-by: Paolo Abeni Signed-off-by: Geliang Tang Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/options.c | 52 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 43 insertions(+), 9 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index bb3a1f3b6e99..b4da08db1221 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -439,6 +439,7 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, struct mptcp_sock *msk = mptcp_sk(subflow->conn); struct mptcp_ext *mpext; unsigned int data_len; + u8 len; /* When skb is not available, we better over-estimate the emitted * options len. A full DSS option (28 bytes) is longer than @@ -474,10 +475,16 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb, * packets that start the first subflow of an MPTCP connection, * as well as the first packet that carries data */ - if (data_len > 0) - *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 4); - else + if (data_len > 0) { + len = TCPOLEN_MPTCP_MPC_ACK_DATA; + if (opts->csum_reqd) { + opts->ext_copy.csum = mpext->csum; + len += TCPOLEN_MPTCP_DSS_CHECKSUM; + } + *size = ALIGN(len, 4); + } else { *size = TCPOLEN_MPTCP_MPC_ACK; + } pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d", subflow, subflow->local_key, subflow->remote_key, @@ -1122,6 +1129,25 @@ static void mptcp_set_rwin(const struct tcp_sock *tp) WRITE_ONCE(msk->rcv_wnd_sent, ack_seq); } +static u16 mptcp_make_csum(const struct mptcp_ext *mpext) +{ + struct csum_pseudo_header header; + __wsum csum; + + /* cfr RFC 8684 3.3.1.: + * the data sequence number used in the pseudo-header is + * always the 64-bit value, irrespective of what length is used in the + * DSS option itself. + */ + header.data_seq = cpu_to_be64(mpext->data_seq); + header.subflow_seq = htonl(mpext->subflow_seq); + header.data_len = htons(mpext->data_len); + header.csum = 0; + + csum = csum_partial(&header, sizeof(header), ~csum_unfold(mpext->csum)); + return (__force u16)csum_fold(csum); +} + void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp, struct mptcp_out_options *opts) { @@ -1129,14 +1155,17 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp, OPTION_MPTCP_MPC_ACK) & opts->suboptions) { u8 len, flag = MPTCP_CAP_HMAC_SHA256; - if (OPTION_MPTCP_MPC_SYN & opts->suboptions) + if (OPTION_MPTCP_MPC_SYN & opts->suboptions) { len = TCPOLEN_MPTCP_MPC_SYN; - else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) + } else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) { len = TCPOLEN_MPTCP_MPC_SYNACK; - else if (opts->ext_copy.data_len) + } else if (opts->ext_copy.data_len) { len = TCPOLEN_MPTCP_MPC_ACK_DATA; - else + if (opts->csum_reqd) + len += TCPOLEN_MPTCP_DSS_CHECKSUM; + } else { len = TCPOLEN_MPTCP_MPC_ACK; + } if (opts->csum_reqd) flag |= MPTCP_CAP_CHECKSUM_REQD; @@ -1159,8 +1188,13 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp, if (!opts->ext_copy.data_len) goto mp_capable_done; - put_unaligned_be32(opts->ext_copy.data_len << 16 | - TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); + if (opts->csum_reqd) { + put_unaligned_be32(opts->ext_copy.data_len << 16 | + mptcp_make_csum(&opts->ext_copy), ptr); + } else { + put_unaligned_be32(opts->ext_copy.data_len << 16 | + TCPOPT_NOP << 8 | TCPOPT_NOP, ptr); + } ptr += 1; } -- 2.20.1