root/net/netlink/diag.c
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/module.h>

#include <net/sock.h>
#include <linux/netlink.h>
#include <linux/sock_diag.h>
#include <linux/netlink_diag.h>
#include <linux/rhashtable.h>

#include "af_netlink.h"

static int sk_diag_dump_groups(struct sock *sk, struct sk_buff *nlskb)
{
        struct netlink_sock *nlk = nlk_sk(sk);

        if (nlk->groups == NULL)
                return 0;

        return nla_put(nlskb, NETLINK_DIAG_GROUPS, NLGRPSZ(nlk->ngroups),
                       nlk->groups);
}

static int sk_diag_put_flags(struct sock *sk, struct sk_buff *skb)
{
        struct netlink_sock *nlk = nlk_sk(sk);
        u32 flags = 0;

        if (nlk->cb_running)
                flags |= NDIAG_FLAG_CB_RUNNING;
        if (nlk_test_bit(RECV_PKTINFO, sk))
                flags |= NDIAG_FLAG_PKTINFO;
        if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
                flags |= NDIAG_FLAG_BROADCAST_ERROR;
        if (nlk_test_bit(RECV_NO_ENOBUFS, sk))
                flags |= NDIAG_FLAG_NO_ENOBUFS;
        if (nlk_test_bit(LISTEN_ALL_NSID, sk))
                flags |= NDIAG_FLAG_LISTEN_ALL_NSID;
        if (nlk_test_bit(CAP_ACK, sk))
                flags |= NDIAG_FLAG_CAP_ACK;

        return nla_put_u32(skb, NETLINK_DIAG_FLAGS, flags);
}

static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
                        struct netlink_diag_req *req,
                        u32 portid, u32 seq, u32 flags, int sk_ino)
{
        struct nlmsghdr *nlh;
        struct netlink_diag_msg *rep;
        struct netlink_sock *nlk = nlk_sk(sk);

        nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
                        flags);
        if (!nlh)
                return -EMSGSIZE;

        rep = nlmsg_data(nlh);
        rep->ndiag_family       = AF_NETLINK;
        rep->ndiag_type         = sk->sk_type;
        rep->ndiag_protocol     = sk->sk_protocol;
        rep->ndiag_state        = sk->sk_state;

        rep->ndiag_ino          = sk_ino;
        rep->ndiag_portid       = nlk->portid;
        rep->ndiag_dst_portid   = nlk->dst_portid;
        rep->ndiag_dst_group    = nlk->dst_group;
        sock_diag_save_cookie(sk, rep->ndiag_cookie);

        if ((req->ndiag_show & NDIAG_SHOW_GROUPS) &&
            sk_diag_dump_groups(sk, skb))
                goto out_nlmsg_trim;

        if ((req->ndiag_show & NDIAG_SHOW_MEMINFO) &&
            sock_diag_put_meminfo(sk, skb, NETLINK_DIAG_MEMINFO))
                goto out_nlmsg_trim;

        if ((req->ndiag_show & NDIAG_SHOW_FLAGS) &&
            sk_diag_put_flags(sk, skb))
                goto out_nlmsg_trim;

        nlmsg_end(skb, nlh);
        return 0;

out_nlmsg_trim:
        nlmsg_cancel(skb, nlh);
        return -EMSGSIZE;
}

static int __netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                                int protocol, int s_num)
{
        struct rhashtable_iter *hti = (void *)cb->args[2];
        struct netlink_table *tbl = &nl_table[protocol];
        struct net *net = sock_net(skb->sk);
        struct netlink_diag_req *req;
        struct netlink_sock *nlsk;
        unsigned long flags;
        struct sock *sk;
        int num = 2;
        int ret = 0;

        req = nlmsg_data(cb->nlh);

        if (s_num > 1)
                goto mc_list;

        num--;

        if (!hti) {
                hti = kmalloc_obj(*hti);
                if (!hti)
                        return -ENOMEM;

                cb->args[2] = (long)hti;
        }

        if (!s_num)
                rhashtable_walk_enter(&tbl->hash, hti);

        rhashtable_walk_start(hti);

        while ((nlsk = rhashtable_walk_next(hti))) {
                if (IS_ERR(nlsk)) {
                        ret = PTR_ERR(nlsk);
                        if (ret == -EAGAIN) {
                                ret = 0;
                                continue;
                        }
                        break;
                }

                sk = (struct sock *)nlsk;

                if (!net_eq(sock_net(sk), net))
                        continue;

                if (sk_diag_fill(sk, skb, req,
                                 NETLINK_CB(cb->skb).portid,
                                 cb->nlh->nlmsg_seq,
                                 NLM_F_MULTI,
                                 sock_i_ino(sk)) < 0) {
                        ret = 1;
                        break;
                }
        }

        rhashtable_walk_stop(hti);

        if (ret)
                goto done;

        rhashtable_walk_exit(hti);
        num++;

mc_list:
        read_lock_irqsave(&nl_table_lock, flags);
        sk_for_each_bound(sk, &tbl->mc_list) {
                if (sk_hashed(sk))
                        continue;
                if (!net_eq(sock_net(sk), net))
                        continue;
                if (num < s_num) {
                        num++;
                        continue;
                }

                if (sk_diag_fill(sk, skb, req,
                                 NETLINK_CB(cb->skb).portid,
                                 cb->nlh->nlmsg_seq,
                                 NLM_F_MULTI,
                                 sock_i_ino(sk)) < 0) {
                        ret = 1;
                        break;
                }
                num++;
        }
        read_unlock_irqrestore(&nl_table_lock, flags);

done:
        cb->args[0] = num;

        return ret;
}

static int netlink_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct netlink_diag_req *req;
        int s_num = cb->args[0];
        int err = 0;

        req = nlmsg_data(cb->nlh);

        if (req->sdiag_protocol == NDIAG_PROTO_ALL) {
                int i;

                for (i = cb->args[1]; i < MAX_LINKS; i++) {
                        err = __netlink_diag_dump(skb, cb, i, s_num);
                        if (err)
                                break;
                        s_num = 0;
                }
                cb->args[1] = i;
        } else {
                if (req->sdiag_protocol >= MAX_LINKS)
                        return -ENOENT;

                err = __netlink_diag_dump(skb, cb, req->sdiag_protocol, s_num);
        }

        return err <= 0 ? err : skb->len;
}

static int netlink_diag_dump_done(struct netlink_callback *cb)
{
        struct rhashtable_iter *hti = (void *)cb->args[2];

        if (cb->args[0] == 1)
                rhashtable_walk_exit(hti);

        kfree(hti);

        return 0;
}

static int netlink_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
{
        int hdrlen = sizeof(struct netlink_diag_req);
        struct net *net = sock_net(skb->sk);

        if (nlmsg_len(h) < hdrlen)
                return -EINVAL;

        if (h->nlmsg_flags & NLM_F_DUMP) {
                struct netlink_dump_control c = {
                        .dump = netlink_diag_dump,
                        .done = netlink_diag_dump_done,
                };
                return netlink_dump_start(net->diag_nlsk, skb, h, &c);
        } else
                return -EOPNOTSUPP;
}

static const struct sock_diag_handler netlink_diag_handler = {
        .owner = THIS_MODULE,
        .family = AF_NETLINK,
        .dump = netlink_diag_handler_dump,
};

static int __init netlink_diag_init(void)
{
        return sock_diag_register(&netlink_diag_handler);
}

static void __exit netlink_diag_exit(void)
{
        sock_diag_unregister(&netlink_diag_handler);
}

module_init(netlink_diag_init);
module_exit(netlink_diag_exit);
MODULE_DESCRIPTION("Netlink-based socket monitoring/diagnostic interface (sock_diag)");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 16 /* AF_NETLINK */);