/*
 * tcp_diag.c   Module for monitoring TCP transport protocols sockets.
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/net.h>
#include <linux/sock_diag.h>
#include <linux/inet_diag.h>

#include <linux/tcp.h>

#include <net/netlink.h>
#include <net/tcp.h>

static void tcp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
                              void *_info)
{
        struct tcp_info *info = _info;

        if (inet_sk_state_load(sk) == TCP_LISTEN) {
                r->idiag_rqueue = sk->sk_ack_backlog;
                r->idiag_wqueue = sk->sk_max_ack_backlog;
        } else if (sk->sk_type == SOCK_STREAM) {
                const struct tcp_sock *tp = tcp_sk(sk);

                r->idiag_rqueue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
                r->idiag_wqueue = tp->write_seq - tp->snd_una;
        }
        if (info)
                tcp_get_info(sk, info);
}

#ifdef CONFIG_TCP_MD5SIG
static void tcp_diag_md5sig_fill(struct tcp_diag_md5sig *info,
                                 const struct tcp_md5sig_key *key)
{
        info->tcpm_family = key->family;
        info->tcpm_prefixlen = key->prefixlen;
        info->tcpm_keylen = key->keylen;
        memcpy(info->tcpm_key, key->key, key->keylen);

        if (key->family == AF_INET)
                info->tcpm_addr[0] = key->addr.a4.s_addr;
        #if IS_ENABLED(CONFIG_IPV6)
        else if (key->family == AF_INET6)
                memcpy(&info->tcpm_addr, &key->addr.a6,
                       sizeof(info->tcpm_addr));
        #endif
}

static int tcp_diag_put_md5sig(struct sk_buff *skb,
                               const struct tcp_md5sig_info *md5sig)
{
        const struct tcp_md5sig_key *key;
        struct tcp_diag_md5sig *info;
        struct nlattr *attr;
        int md5sig_count = 0;

        hlist_for_each_entry_rcu(key, &md5sig->head, node)
                md5sig_count++;
        if (md5sig_count == 0)
                return 0;

        attr = nla_reserve(skb, INET_DIAG_MD5SIG,
                           md5sig_count * sizeof(struct tcp_diag_md5sig));
        if (!attr)
                return -EMSGSIZE;

        info = nla_data(attr);
        memset(info, 0, md5sig_count * sizeof(struct tcp_diag_md5sig));
        hlist_for_each_entry_rcu(key, &md5sig->head, node) {
                tcp_diag_md5sig_fill(info++, key);
                if (--md5sig_count == 0)
                        break;
        }

        return 0;
}
#endif

static int tcp_diag_get_aux(struct sock *sk, bool net_admin,
                            struct sk_buff *skb)
{
#ifdef CONFIG_TCP_MD5SIG
        if (net_admin) {
                struct tcp_md5sig_info *md5sig;
                int err = 0;

                rcu_read_lock();
                md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
                if (md5sig)
                        err = tcp_diag_put_md5sig(skb, md5sig);
                rcu_read_unlock();
                if (err < 0)
                        return err;
        }
#endif

        return 0;
}

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

#ifdef CONFIG_TCP_MD5SIG
        if (net_admin && sk_fullsock(sk)) {
                const struct tcp_md5sig_info *md5sig;
                const struct tcp_md5sig_key *key;
                size_t md5sig_count = 0;

                rcu_read_lock();
                md5sig = rcu_dereference(tcp_sk(sk)->md5sig_info);
                if (md5sig) {
                        hlist_for_each_entry_rcu(key, &md5sig->head, node)
                                md5sig_count++;
                }
                rcu_read_unlock();
                size += nla_total_size(md5sig_count *
                                       sizeof(struct tcp_diag_md5sig));
        }
#endif

        return size;
}

static void tcp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                          const struct inet_diag_req_v2 *r, struct nlattr *bc)
{
        inet_diag_dump_icsk(&tcp_hashinfo, skb, cb, r, bc);
}

static int tcp_diag_dump_one(struct sk_buff *in_skb, const struct nlmsghdr *nlh,
                             const struct inet_diag_req_v2 *req)
{
        return inet_diag_dump_one_icsk(&tcp_hashinfo, in_skb, nlh, req);
}

#ifdef CONFIG_INET_DIAG_DESTROY
static int tcp_diag_destroy(struct sk_buff *in_skb,
                            const struct inet_diag_req_v2 *req)
{
        struct net *net = sock_net(in_skb->sk);
        struct sock *sk = inet_diag_find_one_icsk(net, &tcp_hashinfo, req);
        int err;

        if (IS_ERR(sk))
                return PTR_ERR(sk);

        err = sock_diag_destroy(sk, ECONNABORTED);

        sock_gen_put(sk);

        return err;
}
#endif

static const struct inet_diag_handler tcp_diag_handler = {
        .dump                   = tcp_diag_dump,
        .dump_one               = tcp_diag_dump_one,
        .idiag_get_info         = tcp_diag_get_info,
        .idiag_get_aux          = tcp_diag_get_aux,
        .idiag_get_aux_size     = tcp_diag_get_aux_size,
        .idiag_type             = IPPROTO_TCP,
        .idiag_info_size        = sizeof(struct tcp_info),
#ifdef CONFIG_INET_DIAG_DESTROY
        .destroy                = tcp_diag_destroy,
#endif
};

static int __init tcp_diag_init(void)
{
        return inet_diag_register(&tcp_diag_handler);
}

static void __exit tcp_diag_exit(void)
{
        inet_diag_unregister(&tcp_diag_handler);
}

module_init(tcp_diag_init);
module_exit(tcp_diag_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-6 /* AF_INET - IPPROTO_TCP */);