// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
 * (C) Copyright Red Hat Inc. 2017
 *
 * This file is part of the SCTP kernel implementation
 *
 * These functions implement sctp diag support.
 *
 * Please send any bug reports or fixes you make to the
 * email addresched(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * Written or modified by:
 *    Xin Long <lucien.xin@gmail.com>
 */

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

static void sctp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
                               void *info);

/* define some functions to make asoc/ep fill look clean */
static void inet_diag_msg_sctpasoc_fill(struct inet_diag_msg *r,
                                        struct sock *sk,
                                        struct sctp_association *asoc)
{
        union sctp_addr laddr, paddr;
        struct dst_entry *dst;
        struct timer_list *t3_rtx = &asoc->peer.primary_path->T3_rtx_timer;

        laddr = list_entry(asoc->base.bind_addr.address_list.next,
                           struct sctp_sockaddr_entry, list)->a;
        paddr = asoc->peer.primary_path->ipaddr;
        dst = asoc->peer.primary_path->dst;

        r->idiag_family = sk->sk_family;
        r->id.idiag_sport = htons(asoc->base.bind_addr.port);
        r->id.idiag_dport = htons(asoc->peer.port);
        r->id.idiag_if = dst ? dst->dev->ifindex : 0;
        sock_diag_save_cookie(sk, r->id.idiag_cookie);

#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6) {
                *(struct in6_addr *)r->id.idiag_src = laddr.v6.sin6_addr;
                *(struct in6_addr *)r->id.idiag_dst = paddr.v6.sin6_addr;
        } else
#endif
        {
                memset(&r->id.idiag_src, 0, sizeof(r->id.idiag_src));
                memset(&r->id.idiag_dst, 0, sizeof(r->id.idiag_dst));

                r->id.idiag_src[0] = laddr.v4.sin_addr.s_addr;
                r->id.idiag_dst[0] = paddr.v4.sin_addr.s_addr;
        }

        r->idiag_state = asoc->state;
        if (timer_pending(t3_rtx)) {
                r->idiag_timer = SCTP_EVENT_TIMEOUT_T3_RTX;
                r->idiag_retrans = asoc->rtx_data_chunks;
                r->idiag_expires = jiffies_to_msecs(t3_rtx->expires - jiffies);
        }
}

static int inet_diag_msg_sctpladdrs_fill(struct sk_buff *skb,
                                         struct list_head *address_list)
{
        struct sctp_sockaddr_entry *laddr;
        int addrlen = sizeof(struct sockaddr_storage);
        int addrcnt = 0;
        struct nlattr *attr;
        void *info = NULL;

        rcu_read_lock();
        list_for_each_entry_rcu(laddr, address_list, list)
                addrcnt++;
        rcu_read_unlock();

        attr = nla_reserve(skb, INET_DIAG_LOCALS, addrlen * addrcnt);
        if (!attr)
                return -EMSGSIZE;

        info = nla_data(attr);
        rcu_read_lock();
        list_for_each_entry_rcu(laddr, address_list, list) {
                memcpy(info, &laddr->a, sizeof(laddr->a));
                memset(info + sizeof(laddr->a), 0, addrlen - sizeof(laddr->a));
                info += addrlen;

                if (!--addrcnt)
                        break;
        }
        rcu_read_unlock();

        return 0;
}

static int inet_diag_msg_sctpaddrs_fill(struct sk_buff *skb,
                                        struct sctp_association *asoc)
{
        int addrlen = sizeof(struct sockaddr_storage);
        struct sctp_transport *from;
        struct nlattr *attr;
        void *info = NULL;

        attr = nla_reserve(skb, INET_DIAG_PEERS,
                           addrlen * asoc->peer.transport_count);
        if (!attr)
                return -EMSGSIZE;

        info = nla_data(attr);
        list_for_each_entry(from, &asoc->peer.transport_addr_list,
                            transports) {
                memcpy(info, &from->ipaddr, sizeof(from->ipaddr));
                memset(info + sizeof(from->ipaddr), 0,
                       addrlen - sizeof(from->ipaddr));
                info += addrlen;
        }

        return 0;
}

/* sctp asoc/ep fill*/
static int inet_sctp_diag_fill(struct sock *sk, struct sctp_association *asoc,
                               struct sk_buff *skb,
                               const struct inet_diag_req_v2 *req,
                               struct user_namespace *user_ns,
                               int portid, u32 seq, u16 nlmsg_flags,
                               const struct nlmsghdr *unlh,
                               bool net_admin)
{
        struct sctp_endpoint *ep = sctp_sk(sk)->ep;
        struct list_head *addr_list;
        struct inet_diag_msg *r;
        struct nlmsghdr  *nlh;
        int ext = req->idiag_ext;
        struct sctp_infox infox;
        void *info = NULL;

        nlh = nlmsg_put(skb, portid, seq, unlh->nlmsg_type, sizeof(*r),
                        nlmsg_flags);
        if (!nlh)
                return -EMSGSIZE;

        r = nlmsg_data(nlh);
        BUG_ON(!sk_fullsock(sk));

        r->idiag_timer = 0;
        r->idiag_retrans = 0;
        r->idiag_expires = 0;
        if (asoc) {
                inet_diag_msg_sctpasoc_fill(r, sk, asoc);
        } else {
                inet_diag_msg_common_fill(r, sk);
                r->idiag_state = sk->sk_state;
        }

        if (inet_diag_msg_attrs_fill(sk, skb, r, ext, user_ns, net_admin))
                goto errout;

        if (ext & (1 << (INET_DIAG_SKMEMINFO - 1))) {
                u32 mem[SK_MEMINFO_VARS];
                int amt;

                if (asoc && asoc->ep->sndbuf_policy)
                        amt = asoc->sndbuf_used;
                else
                        amt = sk_wmem_alloc_get(sk);
                mem[SK_MEMINFO_WMEM_ALLOC] = amt;
                if (asoc && asoc->ep->rcvbuf_policy)
                        amt = atomic_read(&asoc->rmem_alloc);
                else
                        amt = sk_rmem_alloc_get(sk);
                mem[SK_MEMINFO_RMEM_ALLOC] = amt;
                mem[SK_MEMINFO_RCVBUF] = sk->sk_rcvbuf;
                mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
                mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
                mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
                mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
                mem[SK_MEMINFO_BACKLOG] = READ_ONCE(sk->sk_backlog.len);
                mem[SK_MEMINFO_DROPS] = sk_drops_read(sk);

                if (nla_put(skb, INET_DIAG_SKMEMINFO, sizeof(mem), &mem) < 0)
                        goto errout;
        }

        if (ext & (1 << (INET_DIAG_INFO - 1))) {
                struct nlattr *attr;

                attr = nla_reserve_64bit(skb, INET_DIAG_INFO,
                                         sizeof(struct sctp_info),
                                         INET_DIAG_PAD);
                if (!attr)
                        goto errout;

                info = nla_data(attr);
        }
        infox.sctpinfo = (struct sctp_info *)info;
        infox.asoc = asoc;
        sctp_diag_get_info(sk, r, &infox);

        addr_list = asoc ? &asoc->base.bind_addr.address_list
                         : &ep->base.bind_addr.address_list;
        if (inet_diag_msg_sctpladdrs_fill(skb, addr_list))
                goto errout;

        if (asoc && (ext & (1 << (INET_DIAG_CONG - 1))))
                if (nla_put_string(skb, INET_DIAG_CONG, "reno") < 0)
                        goto errout;

        if (asoc && inet_diag_msg_sctpaddrs_fill(skb, asoc))
                goto errout;

        nlmsg_end(skb, nlh);
        return 0;

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

/* callback and param */
struct sctp_comm_param {
        struct sk_buff *skb;
        struct netlink_callback *cb;
        const struct inet_diag_req_v2 *r;
        const struct nlmsghdr *nlh;
        bool net_admin;
};

static size_t inet_assoc_attr_size(struct sock *sk,
                                   struct sctp_association *asoc)
{
        int addrlen = sizeof(struct sockaddr_storage);
        int addrcnt = 0;
        struct sctp_sockaddr_entry *laddr;

        list_for_each_entry_rcu(laddr, &asoc->base.bind_addr.address_list,
                                list, lockdep_sock_is_held(sk))
                addrcnt++;

        return    nla_total_size(sizeof(struct sctp_info))
                + nla_total_size(addrlen * asoc->peer.transport_count)
                + nla_total_size(addrlen * addrcnt)
                + nla_total_size(sizeof(struct inet_diag_msg))
                + inet_diag_msg_attrs_size()
                + nla_total_size(sizeof(struct inet_diag_meminfo))
                + 64;
}

static int sctp_sock_dump_one(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p)
{
        struct sctp_association *assoc = tsp->asoc;
        struct sctp_comm_param *commp = p;
        struct sock *sk = ep->base.sk;
        const struct inet_diag_req_v2 *req = commp->r;
        struct sk_buff *skb = commp->skb;
        struct sk_buff *rep;
        int err;

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

        lock_sock(sk);

        rep = nlmsg_new(inet_assoc_attr_size(sk, assoc), GFP_KERNEL);
        if (!rep) {
                release_sock(sk);
                return -ENOMEM;
        }

        if (ep != assoc->ep) {
                err = -EAGAIN;
                goto out;
        }

        err = inet_sctp_diag_fill(sk, assoc, rep, req, sk_user_ns(NETLINK_CB(skb).sk),
                                  NETLINK_CB(skb).portid, commp->nlh->nlmsg_seq, 0,
                                  commp->nlh, commp->net_admin);
        if (err < 0) {
                WARN_ON(err == -EMSGSIZE);
                goto out;
        }
        release_sock(sk);

        return nlmsg_unicast(sock_net(skb->sk)->diag_nlsk, rep, NETLINK_CB(skb).portid);

out:
        release_sock(sk);
        kfree_skb(rep);
        return err;
}

static int sctp_sock_dump(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p)
{
        struct sctp_comm_param *commp = p;
        struct sock *sk = ep->base.sk;
        struct sk_buff *skb = commp->skb;
        struct netlink_callback *cb = commp->cb;
        const struct inet_diag_req_v2 *r = commp->r;
        struct sctp_association *assoc;
        int err = 0;

        lock_sock(sk);
        if (ep != tsp->asoc->ep)
                goto release;
        list_for_each_entry(assoc, &ep->asocs, asocs) {
                if (cb->args[4] < cb->args[1])
                        goto next;

                if (r->id.idiag_sport != htons(assoc->base.bind_addr.port) &&
                    r->id.idiag_sport)
                        goto next;
                if (r->id.idiag_dport != htons(assoc->peer.port) &&
                    r->id.idiag_dport)
                        goto next;

                if (!cb->args[3] &&
                    inet_sctp_diag_fill(sk, NULL, skb, r,
                                        sk_user_ns(NETLINK_CB(cb->skb).sk),
                                        NETLINK_CB(cb->skb).portid,
                                        cb->nlh->nlmsg_seq,
                                        NLM_F_MULTI, cb->nlh,
                                        commp->net_admin) < 0) {
                        err = 1;
                        goto release;
                }
                cb->args[3] = 1;

                if (inet_sctp_diag_fill(sk, assoc, skb, r,
                                        sk_user_ns(NETLINK_CB(cb->skb).sk),
                                        NETLINK_CB(cb->skb).portid,
                                        cb->nlh->nlmsg_seq, 0, cb->nlh,
                                        commp->net_admin) < 0) {
                        err = 1;
                        goto release;
                }
next:
                cb->args[4]++;
        }
        cb->args[1] = 0;
        cb->args[3] = 0;
        cb->args[4] = 0;
release:
        release_sock(sk);
        return err;
}

static int sctp_sock_filter(struct sctp_endpoint *ep, struct sctp_transport *tsp, void *p)
{
        struct sctp_comm_param *commp = p;
        struct sock *sk = ep->base.sk;
        const struct inet_diag_req_v2 *r = commp->r;

        /* find the ep only once through the transports by this condition */
        if (!list_is_first(&tsp->asoc->asocs, &ep->asocs))
                return 0;

        if (r->sdiag_family != AF_UNSPEC && sk->sk_family != r->sdiag_family)
                return 0;

        return 1;
}

static int sctp_ep_dump(struct sctp_endpoint *ep, void *p)
{
        struct sctp_comm_param *commp = p;
        struct sock *sk = ep->base.sk;
        struct sk_buff *skb = commp->skb;
        struct netlink_callback *cb = commp->cb;
        const struct inet_diag_req_v2 *r = commp->r;
        struct net *net = sock_net(skb->sk);
        struct inet_sock *inet = inet_sk(sk);
        int err = 0;

        if (!net_eq(sock_net(sk), net))
                goto out;

        if (cb->args[4] < cb->args[1])
                goto next;

        if (!(r->idiag_states & TCPF_LISTEN) && !list_empty(&ep->asocs))
                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 (inet_sctp_diag_fill(sk, NULL, skb, r,
                                sk_user_ns(NETLINK_CB(cb->skb).sk),
                                NETLINK_CB(cb->skb).portid,
                                cb->nlh->nlmsg_seq, NLM_F_MULTI,
                                cb->nlh, commp->net_admin) < 0) {
                err = 2;
                goto out;
        }
next:
        cb->args[4]++;
out:
        return err;
}

/* define the functions for sctp_diag_handler*/
static void sctp_diag_get_info(struct sock *sk, struct inet_diag_msg *r,
                               void *info)
{
        struct sctp_infox *infox = (struct sctp_infox *)info;

        if (infox->asoc) {
                r->idiag_rqueue = atomic_read(&infox->asoc->rmem_alloc);
                r->idiag_wqueue = infox->asoc->sndbuf_used;
        } else {
                r->idiag_rqueue = READ_ONCE(sk->sk_ack_backlog);
                r->idiag_wqueue = READ_ONCE(sk->sk_max_ack_backlog);
        }
        if (infox->sctpinfo)
                sctp_get_sctp_info(sk, infox->asoc, infox->sctpinfo);
}

static int sctp_diag_dump_one(struct netlink_callback *cb,
                              const struct inet_diag_req_v2 *req)
{
        struct sk_buff *skb = cb->skb;
        struct net *net = sock_net(skb->sk);
        const struct nlmsghdr *nlh = cb->nlh;
        union sctp_addr laddr, paddr;
        int dif = req->id.idiag_if;
        struct sctp_comm_param commp = {
                .skb = skb,
                .r = req,
                .nlh = nlh,
                .net_admin = netlink_net_capable(skb, CAP_NET_ADMIN),
        };

        if (req->sdiag_family == AF_INET) {
                laddr.v4.sin_port = req->id.idiag_sport;
                laddr.v4.sin_addr.s_addr = req->id.idiag_src[0];
                laddr.v4.sin_family = AF_INET;

                paddr.v4.sin_port = req->id.idiag_dport;
                paddr.v4.sin_addr.s_addr = req->id.idiag_dst[0];
                paddr.v4.sin_family = AF_INET;
        } else {
                laddr.v6.sin6_port = req->id.idiag_sport;
                memcpy(&laddr.v6.sin6_addr, req->id.idiag_src,
                       sizeof(laddr.v6.sin6_addr));
                laddr.v6.sin6_family = AF_INET6;

                paddr.v6.sin6_port = req->id.idiag_dport;
                memcpy(&paddr.v6.sin6_addr, req->id.idiag_dst,
                       sizeof(paddr.v6.sin6_addr));
                paddr.v6.sin6_family = AF_INET6;
        }

        return sctp_transport_lookup_process(sctp_sock_dump_one,
                                             net, &laddr, &paddr, &commp, dif);
}

static void sctp_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
                           const struct inet_diag_req_v2 *r)
{
        u32 idiag_states = r->idiag_states;
        struct net *net = sock_net(skb->sk);
        struct sctp_comm_param commp = {
                .skb = skb,
                .cb = cb,
                .r = r,
                .net_admin = netlink_net_capable(cb->skb, CAP_NET_ADMIN),
        };
        int pos = cb->args[2];

        /* eps hashtable dumps
         * args:
         * 0 : if it will traversal listen sock
         * 1 : to record the sock pos of this time's traversal
         * 4 : to work as a temporary variable to traversal list
         */
        if (cb->args[0] == 0) {
                if (!(idiag_states & TCPF_LISTEN))
                        goto skip;
                if (sctp_for_each_endpoint(sctp_ep_dump, &commp))
                        goto done;
skip:
                cb->args[0] = 1;
                cb->args[1] = 0;
                cb->args[4] = 0;
        }

        /* asocs by transport hashtable dump
         * args:
         * 1 : to record the assoc pos of this time's traversal
         * 2 : to record the transport pos of this time's traversal
         * 3 : to mark if we have dumped the ep info of the current asoc
         * 4 : to work as a temporary variable to traversal list
         * 5 : to save the sk we get from travelsing the tsp list.
         */
        if (!(idiag_states & ~(TCPF_LISTEN | TCPF_CLOSE)))
                goto done;

        sctp_transport_traverse_process(sctp_sock_filter, sctp_sock_dump,
                                        net, &pos, &commp);
        cb->args[2] = pos;

done:
        cb->args[1] = cb->args[4];
        cb->args[4] = 0;
}

static const struct inet_diag_handler sctp_diag_handler = {
        .owner           = THIS_MODULE,
        .dump            = sctp_diag_dump,
        .dump_one        = sctp_diag_dump_one,
        .idiag_get_info  = sctp_diag_get_info,
        .idiag_type      = IPPROTO_SCTP,
        .idiag_info_size = sizeof(struct sctp_info),
};

static int __init sctp_diag_init(void)
{
        return inet_diag_register(&sctp_diag_handler);
}

static void __exit sctp_diag_exit(void)
{
        inet_diag_unregister(&sctp_diag_handler);
}

module_init(sctp_diag_init);
module_exit(sctp_diag_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SCTP socket monitoring via SOCK_DIAG");
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 2-132);