root/net/ipv4/udp_diag.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * udp_diag.c   Module for monitoring UDP transport protocols sockets.
 *
 * Authors:     Pavel Emelyanov, <xemul@parallels.com>
 */


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

static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
                        struct netlink_callback *cb,
                        const struct inet_diag_req_v2 *req,
                        bool net_admin)
{
        if (!inet_diag_bc_sk(cb->data, sk))
                return 0;

        return inet_sk_diag_fill(sk, NULL, skb, cb, req, NLM_F_MULTI,
                                 net_admin);
}

static int udp_dump_one(struct udp_table *tbl,
                        struct netlink_callback *cb,
                        const struct inet_diag_req_v2 *req)
{
        struct sk_buff *in_skb = cb->skb;
        int err;
        struct sock *sk = NULL;
        struct sk_buff *rep;
        struct net *net = sock_net(in_skb->sk);

        rcu_read_lock();
        if (req->sdiag_family == AF_INET)
                /* src and dst are swapped for historical reasons */
                sk = __udp4_lib_lookup(net,
                                req->id.idiag_src[0], req->id.idiag_sport,
                                req->id.idiag_dst[0], req->id.idiag_dport,
                                req->id.idiag_if, 0, tbl, NULL);
#if IS_ENABLED(CONFIG_IPV6)
        else if (req->sdiag_family == AF_INET6)
                sk = __udp6_lib_lookup(net,
                                (struct in6_addr *)req->id.idiag_src,
                                req->id.idiag_sport,
                                (struct in6_addr *)req->id.idiag_dst,
                                req->id.idiag_dport,
                                req->id.idiag_if, 0, tbl, NULL);
#endif
        if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
                sk = NULL;
        rcu_read_unlock();
        err = -ENOENT;
        if (!sk)
                goto out_nosk;

        err = sock_diag_check_cookie(sk, req->id.idiag_cookie);
        if (err)
                goto out;

        err = -ENOMEM;
        rep = nlmsg_new(nla_total_size(sizeof(struct inet_diag_msg)) +
                        inet_diag_msg_attrs_size() +
                        nla_total_size(sizeof(struct inet_diag_meminfo)) + 64,
                        GFP_KERNEL);
        if (!rep)
                goto out;

        err = inet_sk_diag_fill(sk, NULL, rep, cb, req, 0,
                                netlink_net_capable(in_skb, CAP_NET_ADMIN));
        if (err < 0) {
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(rep);
                goto out;
        }
        err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid);

out:
        if (sk)
                sock_put(sk);
out_nosk:
        return err;
}

static void udp_dump(struct udp_table *table, struct sk_buff *skb,
                     struct netlink_callback *cb,
                     const struct inet_diag_req_v2 *r)
{
        bool net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN);
        struct net *net = sock_net(skb->sk);
        int num, s_num, slot, s_slot;

        s_slot = cb->args[0];
        num = s_num = cb->args[1];

        for (slot = s_slot; slot <= table->mask; s_num = 0, slot++) {
                struct udp_hslot *hslot = &table->hash[slot];
                struct sock *sk;

                num = 0;

                if (hlist_empty(&hslot->head))
                        continue;

                spin_lock_bh(&hslot->lock);
                sk_for_each(sk, &hslot->head) {
                        struct inet_sock *inet = inet_sk(sk);

                        if (!net_eq(sock_net(sk), net))
                                continue;
                        if (num < s_num)
                                goto next;
                        if (!(r->idiag_states & (1 << sk->sk_state)))
                                goto next;
                        if (r->sdiag_family != AF_UNSPEC &&
                                        sk->sk_family != r->sdiag_family)
                                goto next;
                        if (r->id.idiag_sport != inet->inet_sport &&
                            r->id.idiag_sport)
                                goto next;
                        if (r->id.idiag_dport != inet->inet_dport &&
                            r->id.idiag_dport)
                                goto next;

                        if (sk_diag_dump(sk, skb, cb, r, net_admin) < 0) {
                                spin_unlock_bh(&hslot->lock);
                                goto done;
                        }
next:
                        num++;
                }
                spin_unlock_bh(&hslot->lock);
        }
done:
        cb->args[0] = slot;
        cb->args[1] = num;
}

static void udp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                          const struct inet_diag_req_v2 *r)
{
        udp_dump(sock_net(cb->skb->sk)->ipv4.udp_table, skb, cb, r);
}

static int udp_diag_dump_one(struct netlink_callback *cb,
                             const struct inet_diag_req_v2 *req)
{
        return udp_dump_one(sock_net(cb->skb->sk)->ipv4.udp_table, cb, req);
}

static void udp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
                void *info)
{
        r->idiag_rqueue = udp_rqueue_get(sk);
        r->idiag_wqueue = sk_wmem_alloc_get(sk);
}

#ifdef CONFIG_INET_DIAG_DESTROY
static int __udp_diag_destroy(struct sk_buff *in_skb,
                              const struct inet_diag_req_v2 *req,
                              struct udp_table *tbl)
{
        struct net *net = sock_net(in_skb->sk);
        struct sock *sk;
        int err;

        rcu_read_lock();

        if (req->sdiag_family == AF_INET)
                sk = __udp4_lib_lookup(net,
                                req->id.idiag_dst[0], req->id.idiag_dport,
                                req->id.idiag_src[0], req->id.idiag_sport,
                                req->id.idiag_if, 0, tbl, NULL);
#if IS_ENABLED(CONFIG_IPV6)
        else if (req->sdiag_family == AF_INET6) {
                if (ipv6_addr_v4mapped((struct in6_addr *)req->id.idiag_dst) &&
                    ipv6_addr_v4mapped((struct in6_addr *)req->id.idiag_src))
                        sk = __udp4_lib_lookup(net,
                                        req->id.idiag_dst[3], req->id.idiag_dport,
                                        req->id.idiag_src[3], req->id.idiag_sport,
                                        req->id.idiag_if, 0, tbl, NULL);

                else
                        sk = __udp6_lib_lookup(net,
                                        (struct in6_addr *)req->id.idiag_dst,
                                        req->id.idiag_dport,
                                        (struct in6_addr *)req->id.idiag_src,
                                        req->id.idiag_sport,
                                        req->id.idiag_if, 0, tbl, NULL);
        }
#endif
        else {
                rcu_read_unlock();
                return -EINVAL;
        }

        if (sk && !refcount_inc_not_zero(&sk->sk_refcnt))
                sk = NULL;

        rcu_read_unlock();

        if (!sk)
                return -ENOENT;

        if (sock_diag_check_cookie(sk, req->id.idiag_cookie)) {
                sock_put(sk);
                return -ENOENT;
        }

        err = sock_diag_destroy(sk, ECONNABORTED);

        sock_put(sk);

        return err;
}

static int udp_diag_destroy(struct sk_buff *in_skb,
                            const struct inet_diag_req_v2 *req)
{
        return __udp_diag_destroy(in_skb, req, sock_net(in_skb->sk)->ipv4.udp_table);
}

static int udplite_diag_destroy(struct sk_buff *in_skb,
                                const struct inet_diag_req_v2 *req)
{
        return __udp_diag_destroy(in_skb, req, &udplite_table);
}

#endif

static const struct inet_diag_handler udp_diag_handler = {
        .owner           = THIS_MODULE,
        .dump            = udp_diag_dump,
        .dump_one        = udp_diag_dump_one,
        .idiag_get_info  = udp_diag_get_info,
        .idiag_type      = IPPROTO_UDP,
        .idiag_info_size = 0,
#ifdef CONFIG_INET_DIAG_DESTROY
        .destroy         = udp_diag_destroy,
#endif
};

static void udplite_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                              const struct inet_diag_req_v2 *r)
{
        udp_dump(&udplite_table, skb, cb, r);
}

static int udplite_diag_dump_one(struct netlink_callback *cb,
                                 const struct inet_diag_req_v2 *req)
{
        return udp_dump_one(&udplite_table, cb, req);
}

static const struct inet_diag_handler udplite_diag_handler = {
        .owner           = THIS_MODULE,
        .dump            = udplite_diag_dump,
        .dump_one        = udplite_diag_dump_one,
        .idiag_get_info  = udp_diag_get_info,
        .idiag_type      = IPPROTO_UDPLITE,
        .idiag_info_size = 0,
#ifdef CONFIG_INET_DIAG_DESTROY
        .destroy         = udplite_diag_destroy,
#endif
};

static int __init udp_diag_init(void)
{
        int err;

        err = inet_diag_register(&udp_diag_handler);
        if (err)
                goto out;
        err = inet_diag_register(&udplite_diag_handler);
        if (err)
                goto out_lite;
out:
        return err;
out_lite:
        inet_diag_unregister(&udp_diag_handler);
        goto out;
}

static void __exit udp_diag_exit(void)
{
        inet_diag_unregister(&udplite_diag_handler);
        inet_diag_unregister(&udp_diag_handler);
}

module_init(udp_diag_init);
module_exit(udp_diag_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("UDP socket monitoring via SOCK_DIAG");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-17 /* AF_INET - IPPROTO_UDP */);
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-136 /* AF_INET - IPPROTO_UDPLITE */);