// SPDX-License-Identifier: GPL-2.0
/* MPTCP socket monitoring support
 *
 * Copyright (c) 2019 Red Hat
 *
 * Author: Davide Caratti <dcaratti@redhat.com>
 */

#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/inet_diag.h>
#include <net/netlink.h>
#include "protocol.h"

static int subflow_get_info(struct sock *sk, struct sk_buff *skb, bool net_admin)
{
        struct mptcp_subflow_context *sf;
        struct nlattr *start;
        u32 flags = 0;
        bool slow;
        int err;

        if (inet_sk_state_load(sk) == TCP_LISTEN)
                return 0;

        start = nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP);
        if (!start)
                return -EMSGSIZE;

        slow = lock_sock_fast(sk);
        rcu_read_lock();
        sf = rcu_dereference(inet_csk(sk)->icsk_ulp_data);
        if (!sf) {
                err = 0;
                goto nla_failure;
        }

        if (sf->mp_capable)
                flags |= MPTCP_SUBFLOW_FLAG_MCAP_REM;
        if (sf->request_mptcp)
                flags |= MPTCP_SUBFLOW_FLAG_MCAP_LOC;
        if (sf->mp_join)
                flags |= MPTCP_SUBFLOW_FLAG_JOIN_REM;
        if (sf->request_join)
                flags |= MPTCP_SUBFLOW_FLAG_JOIN_LOC;
        if (sf->backup)
                flags |= MPTCP_SUBFLOW_FLAG_BKUP_REM;
        if (sf->request_bkup)
                flags |= MPTCP_SUBFLOW_FLAG_BKUP_LOC;
        if (READ_ONCE(sf->fully_established))
                flags |= MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED;
        if (sf->conn_finished)
                flags |= MPTCP_SUBFLOW_FLAG_CONNECTED;
        if (sf->map_valid)
                flags |= MPTCP_SUBFLOW_FLAG_MAPVALID;

        if (nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_TOKEN_REM, sf->remote_token) ||
            nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_TOKEN_LOC, sf->token) ||
            nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_FLAGS, flags) ||
            nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_REM, sf->remote_id) ||
            nla_put_u8(skb, MPTCP_SUBFLOW_ATTR_ID_LOC, subflow_get_local_id(sf))) {
                err = -EMSGSIZE;
                goto nla_failure;
        }

        /* Only export seq related counters to user with CAP_NET_ADMIN */
        if (net_admin &&
            (nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ,
                         sf->rel_write_seq) ||
             nla_put_u64_64bit(skb, MPTCP_SUBFLOW_ATTR_MAP_SEQ, sf->map_seq,
                               MPTCP_SUBFLOW_ATTR_PAD) ||
             nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_MAP_SFSEQ,
                         sf->map_subflow_seq) ||
             nla_put_u32(skb, MPTCP_SUBFLOW_ATTR_SSN_OFFSET, sf->ssn_offset) ||
             nla_put_u16(skb, MPTCP_SUBFLOW_ATTR_MAP_DATALEN,
                         sf->map_data_len))) {
                err = -EMSGSIZE;
                goto nla_failure;
        }

        rcu_read_unlock();
        unlock_sock_fast(sk, slow);
        nla_nest_end(skb, start);
        return 0;

nla_failure:
        rcu_read_unlock();
        unlock_sock_fast(sk, slow);
        nla_nest_cancel(skb, start);
        return err;
}

static size_t subflow_get_info_size(const struct sock *sk, bool net_admin)
{
        size_t size = 0;

        size += nla_total_size(0) +     /* INET_ULP_INFO_MPTCP */
                nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_TOKEN_REM */
                nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_TOKEN_LOC */
                nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_FLAGS */
                nla_total_size(1) +     /* MPTCP_SUBFLOW_ATTR_ID_REM */
                nla_total_size(1) +     /* MPTCP_SUBFLOW_ATTR_ID_LOC */
                0;

        if (net_admin)
                size += nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_RELWRITE_SEQ */
                        nla_total_size_64bit(8) +       /* MPTCP_SUBFLOW_ATTR_MAP_SEQ */
                        nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_MAP_SFSEQ */
                        nla_total_size(4) +     /* MPTCP_SUBFLOW_ATTR_SSN_OFFSET */
                        nla_total_size(2) +     /* MPTCP_SUBFLOW_ATTR_MAP_DATALEN */
                        0;

        return size;
}

void mptcp_diag_subflow_init(struct tcp_ulp_ops *ops)
{
        ops->get_info = subflow_get_info;
        ops->get_info_size = subflow_get_info_size;
}