ipv6.c

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/*
 *  DCCP over IPv6
 *  Linux INET6 implementation
 *
 *  Based on net/dccp6/ipv6.c
 *
 *  Arnaldo Carvalho de Melo <[email protected]>
 *
 *  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/random.h>
#include <linux/slab.h>
#include <linux/xfrm.h>

#include <net/addrconf.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/inet_sock.h>
#include <net/inet6_connection_sock.h>
#include <net/inet6_hashtables.h>
#include <net/ip6_route.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/transp_v6.h>
#include <net/ip6_checksum.h>
#include <net/xfrm.h>
#include <net/secure_seq.h>

#include "dccp.h"
#include "ipv6.h"
#include "feat.h"

/* The per-net dccp.v6_ctl_sk is used for sending RSTs and ACKs */

static const struct inet_connection_sock_af_ops dccp_ipv6_mapped;
static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops;

static void dccp_v6_hash(struct sock *sk)
{
    if (sk->sk_state != DCCP_CLOSED) {
        if (inet_csk(sk)->icsk_af_ops == &dccp_ipv6_mapped) {
            inet_hash(sk);
            return;
        }
        local_bh_disable();
        __inet6_hash(sk, NULL);
        local_bh_enable();
    }
}

/* add pseudo-header to DCCP checksum stored in skb->csum */
static inline __sum16 dccp_v6_csum_finish(struct sk_buff *skb,
                      const struct in6_addr *saddr,
                      const struct in6_addr *daddr)
{
    return csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_DCCP, skb->csum);
}

static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb)
{
    struct ipv6_pinfo *np = inet6_sk(sk);
    struct dccp_hdr *dh = dccp_hdr(skb);

    dccp_csum_outgoing(skb);
    dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr);
}

static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)
{
    return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
                         ipv6_hdr(skb)->saddr.s6_addr32,
                         dccp_hdr(skb)->dccph_dport,
                         dccp_hdr(skb)->dccph_sport     );

}

static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
            u8 type, u8 code, int offset, __be32 info)
{
    const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
    const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
    struct dccp_sock *dp;
    struct ipv6_pinfo *np;
    struct sock *sk;
    int err;
    __u64 seq;
    struct net *net = dev_net(skb->dev);

    if (skb->len < offset + sizeof(*dh) ||
        skb->len < offset + __dccp_basic_hdr_len(dh)) {
        ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
                   ICMP6_MIB_INERRORS);
        return;
    }

    sk = inet6_lookup(net, &dccp_hashinfo,
            &hdr->daddr, dh->dccph_dport,
            &hdr->saddr, dh->dccph_sport, inet6_iif(skb));

    if (sk == NULL) {
        ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev),
                   ICMP6_MIB_INERRORS);
        return;
    }

    if (sk->sk_state == DCCP_TIME_WAIT) {
        inet_twsk_put(inet_twsk(sk));
        return;
    }

    bh_lock_sock(sk);
    if (sock_owned_by_user(sk))
        NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);

    if (sk->sk_state == DCCP_CLOSED)
        goto out;

    dp = dccp_sk(sk);
    seq = dccp_hdr_seq(dh);
    if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
        !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
        NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
        goto out;
    }

    np = inet6_sk(sk);

    if (type == NDISC_REDIRECT) {
        struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);

        if (dst)
            dst->ops->redirect(dst, sk, skb);
    }

    if (type == ICMPV6_PKT_TOOBIG) {
        struct dst_entry *dst = NULL;

        if (sock_owned_by_user(sk))
            goto out;
        if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
            goto out;

        dst = inet6_csk_update_pmtu(sk, ntohl(info));
        if (!dst)
            goto out;

        if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst))
            dccp_sync_mss(sk, dst_mtu(dst));
        goto out;
    }

    icmpv6_err_convert(type, code, &err);

    /* Might be for an request_sock */
    switch (sk->sk_state) {
        struct request_sock *req, **prev;
    case DCCP_LISTEN:
        if (sock_owned_by_user(sk))
            goto out;

        req = inet6_csk_search_req(sk, &prev, dh->dccph_dport,
                       &hdr->daddr, &hdr->saddr,
                       inet6_iif(skb));
        if (req == NULL)
            goto out;

        /*
         * ICMPs are not backlogged, hence we cannot get an established
         * socket here.
         */
        WARN_ON(req->sk != NULL);

        if (!between48(seq, dccp_rsk(req)->dreq_iss,
                    dccp_rsk(req)->dreq_gss)) {
            NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
            goto out;
        }

        inet_csk_reqsk_queue_drop(sk, req, prev);
        goto out;

    case DCCP_REQUESTING:
    case DCCP_RESPOND:  /* Cannot happen.
                   It can, it SYNs are crossed. --ANK */
        if (!sock_owned_by_user(sk)) {
            DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
            sk->sk_err = err;
            /*
             * Wake people up to see the error
             * (see connect in sock.c)
             */
            sk->sk_error_report(sk);
            dccp_done(sk);
        } else
            sk->sk_err_soft = err;
        goto out;
    }

    if (!sock_owned_by_user(sk) && np->recverr) {
        sk->sk_err = err;
        sk->sk_error_report(sk);
    } else
        sk->sk_err_soft = err;

out:
    bh_unlock_sock(sk);
    sock_put(sk);
}


static int dccp_v6_send_response(struct sock *sk, struct request_sock *req,
                 struct request_values *rv_unused)
{
    struct inet6_request_sock *ireq6 = inet6_rsk(req);
    struct ipv6_pinfo *np = inet6_sk(sk);
    struct sk_buff *skb;
    struct in6_addr *final_p, final;
    struct flowi6 fl6;
    int err = -1;
    struct dst_entry *dst;

    memset(&fl6, 0, sizeof(fl6));
    fl6.flowi6_proto = IPPROTO_DCCP;
    fl6.daddr = ireq6->rmt_addr;
    fl6.saddr = ireq6->loc_addr;
    fl6.flowlabel = 0;
    fl6.flowi6_oif = ireq6->iif;
    fl6.fl6_dport = inet_rsk(req)->rmt_port;
    fl6.fl6_sport = inet_rsk(req)->loc_port;
    security_req_classify_flow(req, flowi6_to_flowi(&fl6));


    final_p = fl6_update_dst(&fl6, np->opt, &final);

    dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);
    if (IS_ERR(dst)) {
        err = PTR_ERR(dst);
        dst = NULL;
        goto done;
    }

    skb = dccp_make_response(sk, dst, req);
    if (skb != NULL) {
        struct dccp_hdr *dh = dccp_hdr(skb);

        dh->dccph_checksum = dccp_v6_csum_finish(skb,
                             &ireq6->loc_addr,
                             &ireq6->rmt_addr);
        fl6.daddr = ireq6->rmt_addr;
        err = ip6_xmit(sk, skb, &fl6, np->opt, np->tclass);
        err = net_xmit_eval(err);
    }

done:
    dst_release(dst);
    return err;
}

static void dccp_v6_reqsk_destructor(struct request_sock *req)
{
    dccp_feat_list_purge(&dccp_rsk(req)->dreq_featneg);
    if (inet6_rsk(req)->pktopts != NULL)
        kfree_skb(inet6_rsk(req)->pktopts);
}

static void dccp_v6_ctl_send_reset(struct sock *sk, struct sk_buff *rxskb)
{
    const struct ipv6hdr *rxip6h;
    struct sk_buff *skb;
    struct flowi6 fl6;
    struct net *net = dev_net(skb_dst(rxskb)->dev);
    struct sock *ctl_sk = net->dccp.v6_ctl_sk;
    struct dst_entry *dst;

    if (dccp_hdr(rxskb)->dccph_type == DCCP_PKT_RESET)
        return;

    if (!ipv6_unicast_destination(rxskb))
        return;

    skb = dccp_ctl_make_reset(ctl_sk, rxskb);
    if (skb == NULL)
        return;

    rxip6h = ipv6_hdr(rxskb);
    dccp_hdr(skb)->dccph_checksum = dccp_v6_csum_finish(skb, &rxip6h->saddr,
                                &rxip6h->daddr);

    memset(&fl6, 0, sizeof(fl6));
    fl6.daddr = rxip6h->saddr;
    fl6.saddr = rxip6h->daddr;

    fl6.flowi6_proto = IPPROTO_DCCP;
    fl6.flowi6_oif = inet6_iif(rxskb);
    fl6.fl6_dport = dccp_hdr(skb)->dccph_dport;
    fl6.fl6_sport = dccp_hdr(skb)->dccph_sport;
    security_skb_classify_flow(rxskb, flowi6_to_flowi(&fl6));

    /* sk = NULL, but it is safe for now. RST socket required. */
    dst = ip6_dst_lookup_flow(ctl_sk, &fl6, NULL, false);
    if (!IS_ERR(dst)) {
        skb_dst_set(skb, dst);
        ip6_xmit(ctl_sk, skb, &fl6, NULL, 0);
        DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
        DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
        return;
    }

    kfree_skb(skb);
}

static struct request_sock_ops dccp6_request_sock_ops = {
    .family     = AF_INET6,
    .obj_size   = sizeof(struct dccp6_request_sock),
    .rtx_syn_ack    = dccp_v6_send_response,
    .send_ack   = dccp_reqsk_send_ack,
    .destructor = dccp_v6_reqsk_destructor,
    .send_reset = dccp_v6_ctl_send_reset,
    .syn_ack_timeout = dccp_syn_ack_timeout,
};

static struct sock *dccp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
{
    const struct dccp_hdr *dh = dccp_hdr(skb);
    const struct ipv6hdr *iph = ipv6_hdr(skb);
    struct sock *nsk;
    struct request_sock **prev;
    /* Find possible connection requests. */
    struct request_sock *req = inet6_csk_search_req(sk, &prev,
                            dh->dccph_sport,
                            &iph->saddr,
                            &iph->daddr,
                            inet6_iif(skb));
    if (req != NULL)
        return dccp_check_req(sk, skb, req, prev);

    nsk = __inet6_lookup_established(sock_net(sk), &dccp_hashinfo,
                     &iph->saddr, dh->dccph_sport,
                     &iph->daddr, ntohs(dh->dccph_dport),
                     inet6_iif(skb));
    if (nsk != NULL) {
        if (nsk->sk_state != DCCP_TIME_WAIT) {
            bh_lock_sock(nsk);
            return nsk;
        }
        inet_twsk_put(inet_twsk(nsk));
        return NULL;
    }

    return sk;
}

static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
    struct request_sock *req;
    struct dccp_request_sock *dreq;
    struct inet6_request_sock *ireq6;
    struct ipv6_pinfo *np = inet6_sk(sk);
    const __be32 service = dccp_hdr_request(skb)->dccph_req_service;
    struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);

    if (skb->protocol == htons(ETH_P_IP))
        return dccp_v4_conn_request(sk, skb);

    if (!ipv6_unicast_destination(skb))
        return 0;   /* discard, don't send a reset here */

    if (dccp_bad_service_code(sk, service)) {
        dcb->dccpd_reset_code = DCCP_RESET_CODE_BAD_SERVICE_CODE;
        goto drop;
    }
    /*
     * There are no SYN attacks on IPv6, yet...
     */
    dcb->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
    if (inet_csk_reqsk_queue_is_full(sk))
        goto drop;

    if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
        goto drop;

    req = inet6_reqsk_alloc(&dccp6_request_sock_ops);
    if (req == NULL)
        goto drop;

    if (dccp_reqsk_init(req, dccp_sk(sk), skb))
        goto drop_and_free;

    dreq = dccp_rsk(req);
    if (dccp_parse_options(sk, dreq, skb))
        goto drop_and_free;

    if (security_inet_conn_request(sk, skb, req))
        goto drop_and_free;

    ireq6 = inet6_rsk(req);
    ireq6->rmt_addr = ipv6_hdr(skb)->saddr;
    ireq6->loc_addr = ipv6_hdr(skb)->daddr;

    if (ipv6_opt_accepted(sk, skb) ||
        np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
        np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim) {
        atomic_inc(&skb->users);
        ireq6->pktopts = skb;
    }
    ireq6->iif = sk->sk_bound_dev_if;

    /* So that link locals have meaning */
    if (!sk->sk_bound_dev_if &&
        ipv6_addr_type(&ireq6->rmt_addr) & IPV6_ADDR_LINKLOCAL)
        ireq6->iif = inet6_iif(skb);

    /*
     * Step 3: Process LISTEN state
     *
     *   Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
     *
     * Setting S.SWL/S.SWH to is deferred to dccp_create_openreq_child().
     */
    dreq->dreq_isr     = dcb->dccpd_seq;
    dreq->dreq_gsr     = dreq->dreq_isr;
    dreq->dreq_iss     = dccp_v6_init_sequence(skb);
    dreq->dreq_gss     = dreq->dreq_iss;
    dreq->dreq_service = service;

    if (dccp_v6_send_response(sk, req, NULL))
        goto drop_and_free;

    inet6_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);
    return 0;

drop_and_free:
    reqsk_free(req);
drop:
    DCCP_INC_STATS_BH(DCCP_MIB_ATTEMPTFAILS);
    return -1;
}

static struct sock *dccp_v6_request_recv_sock(struct sock *sk,
                          struct sk_buff *skb,
                          struct request_sock *req,
                          struct dst_entry *dst)
{
    struct inet6_request_sock *ireq6 = inet6_rsk(req);
    struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
    struct inet_sock *newinet;
    struct dccp6_sock *newdp6;
    struct sock *newsk;

    if (skb->protocol == htons(ETH_P_IP)) {
        /*
         *  v6 mapped
         */
        newsk = dccp_v4_request_recv_sock(sk, skb, req, dst);
        if (newsk == NULL)
            return NULL;

        newdp6 = (struct dccp6_sock *)newsk;
        newinet = inet_sk(newsk);
        newinet->pinet6 = &newdp6->inet6;
        newnp = inet6_sk(newsk);

        memcpy(newnp, np, sizeof(struct ipv6_pinfo));

        ipv6_addr_set_v4mapped(newinet->inet_daddr, &newnp->daddr);

        ipv6_addr_set_v4mapped(newinet->inet_saddr, &newnp->saddr);

        newnp->rcv_saddr = newnp->saddr;

        inet_csk(newsk)->icsk_af_ops = &dccp_ipv6_mapped;
        newsk->sk_backlog_rcv = dccp_v4_do_rcv;
        newnp->pktoptions  = NULL;
        newnp->opt     = NULL;
        newnp->mcast_oif   = inet6_iif(skb);
        newnp->mcast_hops  = ipv6_hdr(skb)->hop_limit;

        /*
         * No need to charge this sock to the relevant IPv6 refcnt debug socks count
         * here, dccp_create_openreq_child now does this for us, see the comment in
         * that function for the gory details. -acme
         */

        /* It is tricky place. Until this moment IPv4 tcp
           worked with IPv6 icsk.icsk_af_ops.
           Sync it now.
         */
        dccp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);

        return newsk;
    }


    if (sk_acceptq_is_full(sk))
        goto out_overflow;

    if (dst == NULL) {
        struct in6_addr *final_p, final;
        struct flowi6 fl6;

        memset(&fl6, 0, sizeof(fl6));
        fl6.flowi6_proto = IPPROTO_DCCP;
        fl6.daddr = ireq6->rmt_addr;
        final_p = fl6_update_dst(&fl6, np->opt, &final);
        fl6.saddr = ireq6->loc_addr;
        fl6.flowi6_oif = sk->sk_bound_dev_if;
        fl6.fl6_dport = inet_rsk(req)->rmt_port;
        fl6.fl6_sport = inet_rsk(req)->loc_port;
        security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

        dst = ip6_dst_lookup_flow(sk, &fl6, final_p, false);
        if (IS_ERR(dst))
            goto out;
    }

    newsk = dccp_create_openreq_child(sk, req, skb);
    if (newsk == NULL)
        goto out_nonewsk;

    /*
     * No need to charge this sock to the relevant IPv6 refcnt debug socks
     * count here, dccp_create_openreq_child now does this for us, see the
     * comment in that function for the gory details. -acme
     */

    __ip6_dst_store(newsk, dst, NULL, NULL);
    newsk->sk_route_caps = dst->dev->features & ~(NETIF_F_IP_CSUM |
                              NETIF_F_TSO);
    newdp6 = (struct dccp6_sock *)newsk;
    newinet = inet_sk(newsk);
    newinet->pinet6 = &newdp6->inet6;
    newnp = inet6_sk(newsk);

    memcpy(newnp, np, sizeof(struct ipv6_pinfo));

    newnp->daddr = ireq6->rmt_addr;
    newnp->saddr = ireq6->loc_addr;
    newnp->rcv_saddr = ireq6->loc_addr;
    newsk->sk_bound_dev_if = ireq6->iif;

    /* Now IPv6 options...

       First: no IPv4 options.
     */
    newinet->inet_opt = NULL;

    /* Clone RX bits */
    newnp->rxopt.all = np->rxopt.all;

    /* Clone pktoptions received with SYN */
    newnp->pktoptions = NULL;
    if (ireq6->pktopts != NULL) {
        newnp->pktoptions = skb_clone(ireq6->pktopts, GFP_ATOMIC);
        consume_skb(ireq6->pktopts);
        ireq6->pktopts = NULL;
        if (newnp->pktoptions)
            skb_set_owner_r(newnp->pktoptions, newsk);
    }
    newnp->opt    = NULL;
    newnp->mcast_oif  = inet6_iif(skb);
    newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;

    /*
     * Clone native IPv6 options from listening socket (if any)
     *
     * Yes, keeping reference count would be much more clever, but we make
     * one more one thing there: reattach optmem to newsk.
     */
    if (np->opt != NULL)
        newnp->opt = ipv6_dup_options(newsk, np->opt);

    inet_csk(newsk)->icsk_ext_hdr_len = 0;
    if (newnp->opt != NULL)
        inet_csk(newsk)->icsk_ext_hdr_len = (newnp->opt->opt_nflen +
                             newnp->opt->opt_flen);

    dccp_sync_mss(newsk, dst_mtu(dst));

    newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
    newinet->inet_rcv_saddr = LOOPBACK4_IPV6;

    if (__inet_inherit_port(sk, newsk) < 0) {
        sock_put(newsk);
        goto out;
    }
    __inet6_hash(newsk, NULL);

    return newsk;

out_overflow:
    NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
out_nonewsk:
    dst_release(dst);
out:
    NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
    return NULL;
}

/* The socket must have it's spinlock held when we get
 * here.
 *
 * We have a potential double-lock case here, so even when
 * doing backlog processing we use the BH locking scheme.
 * This is because we cannot sleep with the original spinlock
 * held.
 */
static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
{
    struct ipv6_pinfo *np = inet6_sk(sk);
    struct sk_buff *opt_skb = NULL;

    /* Imagine: socket is IPv6. IPv4 packet arrives,
       goes to IPv4 receive handler and backlogged.
       From backlog it always goes here. Kerboom...
       Fortunately, dccp_rcv_established and rcv_established
       handle them correctly, but it is not case with
       dccp_v6_hnd_req and dccp_v6_ctl_send_reset().   --ANK
     */

    if (skb->protocol == htons(ETH_P_IP))
        return dccp_v4_do_rcv(sk, skb);

    if (sk_filter(sk, skb))
        goto discard;

    /*
     * socket locking is here for SMP purposes as backlog rcv is currently
     * called with bh processing disabled.
     */

    /* Do Stevens' IPV6_PKTOPTIONS.

       Yes, guys, it is the only place in our code, where we
       may make it not affecting IPv4.
       The rest of code is protocol independent,
       and I do not like idea to uglify IPv4.

       Actually, all the idea behind IPV6_PKTOPTIONS
       looks not very well thought. For now we latch
       options, received in the last packet, enqueued
       by tcp. Feel free to propose better solution.
                           --ANK (980728)
     */
    if (np->rxopt.all)
    /*
     * FIXME: Add handling of IPV6_PKTOPTIONS skb. See the comments below
     *        (wrt ipv6_pktopions) and net/ipv6/tcp_ipv6.c for an example.
     */
        opt_skb = skb_clone(skb, GFP_ATOMIC);

    if (sk->sk_state == DCCP_OPEN) { /* Fast path */
        if (dccp_rcv_established(sk, skb, dccp_hdr(skb), skb->len))
            goto reset;
        if (opt_skb) {
            /* XXX This is where we would goto ipv6_pktoptions. */
            __kfree_skb(opt_skb);
        }
        return 0;
    }

    /*
     *  Step 3: Process LISTEN state
     *     If S.state == LISTEN,
     *   If P.type == Request or P contains a valid Init Cookie option,
     *        (* Must scan the packet's options to check for Init
     *       Cookies.  Only Init Cookies are processed here,
     *       however; other options are processed in Step 8.  This
     *       scan need only be performed if the endpoint uses Init
     *       Cookies *)
     *        (* Generate a new socket and switch to that socket *)
     *        Set S := new socket for this port pair
     *        S.state = RESPOND
     *        Choose S.ISS (initial seqno) or set from Init Cookies
     *        Initialize S.GAR := S.ISS
     *        Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
     *        Continue with S.state == RESPOND
     *        (* A Response packet will be generated in Step 11 *)
     *   Otherwise,
     *        Generate Reset(No Connection) unless P.type == Reset
     *        Drop packet and return
     *
     * NOTE: the check for the packet types is done in
     *   dccp_rcv_state_process
     */
    if (sk->sk_state == DCCP_LISTEN) {
        struct sock *nsk = dccp_v6_hnd_req(sk, skb);

        if (nsk == NULL)
            goto discard;
        /*
         * Queue it on the new socket if the new socket is active,
         * otherwise we just shortcircuit this and continue with
         * the new socket..
         */
        if (nsk != sk) {
            if (dccp_child_process(sk, nsk, skb))
                goto reset;
            if (opt_skb != NULL)
                __kfree_skb(opt_skb);
            return 0;
        }
    }

    if (dccp_rcv_state_process(sk, skb, dccp_hdr(skb), skb->len))
        goto reset;
    if (opt_skb) {
        /* XXX This is where we would goto ipv6_pktoptions. */
        __kfree_skb(opt_skb);
    }
    return 0;

reset:
    dccp_v6_ctl_send_reset(sk, skb);
discard:
    if (opt_skb != NULL)
        __kfree_skb(opt_skb);
    kfree_skb(skb);
    return 0;
}

static int dccp_v6_rcv(struct sk_buff *skb)
{
    const struct dccp_hdr *dh;
    struct sock *sk;
    int min_cov;

    /* Step 1: Check header basics */

    if (dccp_invalid_packet(skb))
        goto discard_it;

    /* Step 1: If header checksum is incorrect, drop packet and return. */
    if (dccp_v6_csum_finish(skb, &ipv6_hdr(skb)->saddr,
                     &ipv6_hdr(skb)->daddr)) {
        DCCP_WARN("dropped packet with invalid checksum\n");
        goto discard_it;
    }

    dh = dccp_hdr(skb);

    DCCP_SKB_CB(skb)->dccpd_seq  = dccp_hdr_seq(dh);
    DCCP_SKB_CB(skb)->dccpd_type = dh->dccph_type;

    if (dccp_packet_without_ack(skb))
        DCCP_SKB_CB(skb)->dccpd_ack_seq = DCCP_PKT_WITHOUT_ACK_SEQ;
    else
        DCCP_SKB_CB(skb)->dccpd_ack_seq = dccp_hdr_ack_seq(skb);

    /* Step 2:
     *  Look up flow ID in table and get corresponding socket */
    sk = __inet6_lookup_skb(&dccp_hashinfo, skb,
                    dh->dccph_sport, dh->dccph_dport);
    /*
     * Step 2:
     *  If no socket ...
     */
    if (sk == NULL) {
        dccp_pr_debug("failed to look up flow ID in table and "
                  "get corresponding socket\n");
        goto no_dccp_socket;
    }

    /*
     * Step 2:
     *  ... or S.state == TIMEWAIT,
     *      Generate Reset(No Connection) unless P.type == Reset
     *      Drop packet and return
     */
    if (sk->sk_state == DCCP_TIME_WAIT) {
        dccp_pr_debug("sk->sk_state == DCCP_TIME_WAIT: do_time_wait\n");
        inet_twsk_put(inet_twsk(sk));
        goto no_dccp_socket;
    }

    /*
     * RFC 4340, sec. 9.2.1: Minimum Checksum Coverage
     *  o if MinCsCov = 0, only packets with CsCov = 0 are accepted
     *  o if MinCsCov > 0, also accept packets with CsCov >= MinCsCov
     */
    min_cov = dccp_sk(sk)->dccps_pcrlen;
    if (dh->dccph_cscov  &&  (min_cov == 0 || dh->dccph_cscov < min_cov))  {
        dccp_pr_debug("Packet CsCov %d does not satisfy MinCsCov %d\n",
                  dh->dccph_cscov, min_cov);
        /* FIXME: send Data Dropped option (see also dccp_v4_rcv) */
        goto discard_and_relse;
    }

    if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
        goto discard_and_relse;

    return sk_receive_skb(sk, skb, 1) ? -1 : 0;

no_dccp_socket:
    if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
        goto discard_it;
    /*
     * Step 2:
     *  If no socket ...
     *      Generate Reset(No Connection) unless P.type == Reset
     *      Drop packet and return
     */
    if (dh->dccph_type != DCCP_PKT_RESET) {
        DCCP_SKB_CB(skb)->dccpd_reset_code =
                    DCCP_RESET_CODE_NO_CONNECTION;
        dccp_v6_ctl_send_reset(sk, skb);
    }

discard_it:
    kfree_skb(skb);
    return 0;

discard_and_relse:
    sock_put(sk);
    goto discard_it;
}

static int dccp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
               int addr_len)
{
    struct sockaddr_in6 *usin = (struct sockaddr_in6 *)uaddr;
    struct inet_connection_sock *icsk = inet_csk(sk);
    struct inet_sock *inet = inet_sk(sk);
    struct ipv6_pinfo *np = inet6_sk(sk);
    struct dccp_sock *dp = dccp_sk(sk);
    struct in6_addr *saddr = NULL, *final_p, final;
    struct flowi6 fl6;
    struct dst_entry *dst;
    int addr_type;
    int err;

    dp->dccps_role = DCCP_ROLE_CLIENT;

    if (addr_len < SIN6_LEN_RFC2133)
        return -EINVAL;

    if (usin->sin6_family != AF_INET6)
        return -EAFNOSUPPORT;

    memset(&fl6, 0, sizeof(fl6));

    if (np->sndflow) {
        fl6.flowlabel = usin->sin6_flowinfo & IPV6_FLOWINFO_MASK;
        IP6_ECN_flow_init(fl6.flowlabel);
        if (fl6.flowlabel & IPV6_FLOWLABEL_MASK) {
            struct ip6_flowlabel *flowlabel;
            flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
            if (flowlabel == NULL)
                return -EINVAL;
            usin->sin6_addr = flowlabel->dst;
            fl6_sock_release(flowlabel);
        }
    }
    /*
     * connect() to INADDR_ANY means loopback (BSD'ism).
     */
    if (ipv6_addr_any(&usin->sin6_addr))
        usin->sin6_addr.s6_addr[15] = 1;

    addr_type = ipv6_addr_type(&usin->sin6_addr);

    if (addr_type & IPV6_ADDR_MULTICAST)
        return -ENETUNREACH;

    if (addr_type & IPV6_ADDR_LINKLOCAL) {
        if (addr_len >= sizeof(struct sockaddr_in6) &&
            usin->sin6_scope_id) {
            /* If interface is set while binding, indices
             * must coincide.
             */
            if (sk->sk_bound_dev_if &&
                sk->sk_bound_dev_if != usin->sin6_scope_id)
                return -EINVAL;

            sk->sk_bound_dev_if = usin->sin6_scope_id;
        }

        /* Connect to link-local address requires an interface */
        if (!sk->sk_bound_dev_if)
            return -EINVAL;
    }

    np->daddr = usin->sin6_addr;
    np->flow_label = fl6.flowlabel;

    /*
     * DCCP over IPv4
     */
    if (addr_type == IPV6_ADDR_MAPPED) {
        u32 exthdrlen = icsk->icsk_ext_hdr_len;
        struct sockaddr_in sin;

        SOCK_DEBUG(sk, "connect: ipv4 mapped\n");

        if (__ipv6_only_sock(sk))
            return -ENETUNREACH;

        sin.sin_family = AF_INET;
        sin.sin_port = usin->sin6_port;
        sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];

        icsk->icsk_af_ops = &dccp_ipv6_mapped;
        sk->sk_backlog_rcv = dccp_v4_do_rcv;

        err = dccp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
        if (err) {
            icsk->icsk_ext_hdr_len = exthdrlen;
            icsk->icsk_af_ops = &dccp_ipv6_af_ops;
            sk->sk_backlog_rcv = dccp_v6_do_rcv;
            goto failure;
        }
        ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);
        ipv6_addr_set_v4mapped(inet->inet_rcv_saddr, &np->rcv_saddr);

        return err;
    }

    if (!ipv6_addr_any(&np->rcv_saddr))
        saddr = &np->rcv_saddr;

    fl6.flowi6_proto = IPPROTO_DCCP;
    fl6.daddr = np->daddr;
    fl6.saddr = saddr ? *saddr : np->saddr;
    fl6.flowi6_oif = sk->sk_bound_dev_if;
    fl6.fl6_dport = usin->sin6_port;
    fl6.fl6_sport = inet->inet_sport;
    security_sk_classify_flow(sk, flowi6_to_flowi(&fl6));

    final_p = fl6_update_dst(&fl6, np->opt, &final);

    dst = ip6_dst_lookup_flow(sk, &fl6, final_p, true);
    if (IS_ERR(dst)) {
        err = PTR_ERR(dst);
        goto failure;
    }

    if (saddr == NULL) {
        saddr = &fl6.saddr;
        np->rcv_saddr = *saddr;
    }

    /* set the source address */
    np->saddr = *saddr;
    inet->inet_rcv_saddr = LOOPBACK4_IPV6;

    __ip6_dst_store(sk, dst, NULL, NULL);

    icsk->icsk_ext_hdr_len = 0;
    if (np->opt != NULL)
        icsk->icsk_ext_hdr_len = (np->opt->opt_flen +
                      np->opt->opt_nflen);

    inet->inet_dport = usin->sin6_port;

    dccp_set_state(sk, DCCP_REQUESTING);
    err = inet6_hash_connect(&dccp_death_row, sk);
    if (err)
        goto late_failure;

    dp->dccps_iss = secure_dccpv6_sequence_number(np->saddr.s6_addr32,
                              np->daddr.s6_addr32,
                              inet->inet_sport,
                              inet->inet_dport);
    err = dccp_connect(sk);
    if (err)
        goto late_failure;

    return 0;

late_failure:
    dccp_set_state(sk, DCCP_CLOSED);
    __sk_dst_reset(sk);
failure:
    inet->inet_dport = 0;
    sk->sk_route_caps = 0;
    return err;
}

static const struct inet_connection_sock_af_ops dccp_ipv6_af_ops = {
    .queue_xmit    = inet6_csk_xmit,
    .send_check    = dccp_v6_send_check,
    .rebuild_header    = inet6_sk_rebuild_header,
    .conn_request      = dccp_v6_conn_request,
    .syn_recv_sock     = dccp_v6_request_recv_sock,
    .net_header_len    = sizeof(struct ipv6hdr),
    .setsockopt    = ipv6_setsockopt,
    .getsockopt    = ipv6_getsockopt,
    .addr2sockaddr     = inet6_csk_addr2sockaddr,
    .sockaddr_len      = sizeof(struct sockaddr_in6),
    .bind_conflict     = inet6_csk_bind_conflict,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_ipv6_setsockopt,
    .compat_getsockopt = compat_ipv6_getsockopt,
#endif
};

/*
 *  DCCP over IPv4 via INET6 API
 */
static const struct inet_connection_sock_af_ops dccp_ipv6_mapped = {
    .queue_xmit    = ip_queue_xmit,
    .send_check    = dccp_v4_send_check,
    .rebuild_header    = inet_sk_rebuild_header,
    .conn_request      = dccp_v6_conn_request,
    .syn_recv_sock     = dccp_v6_request_recv_sock,
    .net_header_len    = sizeof(struct iphdr),
    .setsockopt    = ipv6_setsockopt,
    .getsockopt    = ipv6_getsockopt,
    .addr2sockaddr     = inet6_csk_addr2sockaddr,
    .sockaddr_len      = sizeof(struct sockaddr_in6),
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_ipv6_setsockopt,
    .compat_getsockopt = compat_ipv6_getsockopt,
#endif
};

/* NOTE: A lot of things set to zero explicitly by call to
 *       sk_alloc() so need not be done here.
 */
static int dccp_v6_init_sock(struct sock *sk)
{
    static __u8 dccp_v6_ctl_sock_initialized;
    int err = dccp_init_sock(sk, dccp_v6_ctl_sock_initialized);

    if (err == 0) {
        if (unlikely(!dccp_v6_ctl_sock_initialized))
            dccp_v6_ctl_sock_initialized = 1;
        inet_csk(sk)->icsk_af_ops = &dccp_ipv6_af_ops;
    }

    return err;
}

static void dccp_v6_destroy_sock(struct sock *sk)
{
    dccp_destroy_sock(sk);
    inet6_destroy_sock(sk);
}

static struct timewait_sock_ops dccp6_timewait_sock_ops = {
    .twsk_obj_size  = sizeof(struct dccp6_timewait_sock),
};

static struct proto dccp_v6_prot = {
    .name          = "DCCPv6",
    .owner         = THIS_MODULE,
    .close         = dccp_close,
    .connect       = dccp_v6_connect,
    .disconnect    = dccp_disconnect,
    .ioctl         = dccp_ioctl,
    .init          = dccp_v6_init_sock,
    .setsockopt    = dccp_setsockopt,
    .getsockopt    = dccp_getsockopt,
    .sendmsg       = dccp_sendmsg,
    .recvmsg       = dccp_recvmsg,
    .backlog_rcv       = dccp_v6_do_rcv,
    .hash          = dccp_v6_hash,
    .unhash        = inet_unhash,
    .accept        = inet_csk_accept,
    .get_port      = inet_csk_get_port,
    .shutdown      = dccp_shutdown,
    .destroy       = dccp_v6_destroy_sock,
    .orphan_count      = &dccp_orphan_count,
    .max_header    = MAX_DCCP_HEADER,
    .obj_size      = sizeof(struct dccp6_sock),
    .slab_flags    = SLAB_DESTROY_BY_RCU,
    .rsk_prot      = &dccp6_request_sock_ops,
    .twsk_prot     = &dccp6_timewait_sock_ops,
    .h.hashinfo    = &dccp_hashinfo,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_dccp_setsockopt,
    .compat_getsockopt = compat_dccp_getsockopt,
#endif
};

static const struct inet6_protocol dccp_v6_protocol = {
    .handler    = dccp_v6_rcv,
    .err_handler    = dccp_v6_err,
    .flags      = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
};

static const struct proto_ops inet6_dccp_ops = {
    .family        = PF_INET6,
    .owner         = THIS_MODULE,
    .release       = inet6_release,
    .bind          = inet6_bind,
    .connect       = inet_stream_connect,
    .socketpair    = sock_no_socketpair,
    .accept        = inet_accept,
    .getname       = inet6_getname,
    .poll          = dccp_poll,
    .ioctl         = inet6_ioctl,
    .listen        = inet_dccp_listen,
    .shutdown      = inet_shutdown,
    .setsockopt    = sock_common_setsockopt,
    .getsockopt    = sock_common_getsockopt,
    .sendmsg       = inet_sendmsg,
    .recvmsg       = sock_common_recvmsg,
    .mmap          = sock_no_mmap,
    .sendpage      = sock_no_sendpage,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

static struct inet_protosw dccp_v6_protosw = {
    .type       = SOCK_DCCP,
    .protocol   = IPPROTO_DCCP,
    .prot       = &dccp_v6_prot,
    .ops        = &inet6_dccp_ops,
    .flags      = INET_PROTOSW_ICSK,
};

static int __net_init dccp_v6_init_net(struct net *net)
{
    if (dccp_hashinfo.bhash == NULL)
        return -ESOCKTNOSUPPORT;

    return inet_ctl_sock_create(&net->dccp.v6_ctl_sk, PF_INET6,
                    SOCK_DCCP, IPPROTO_DCCP, net);
}

static void __net_exit dccp_v6_exit_net(struct net *net)
{
    inet_ctl_sock_destroy(net->dccp.v6_ctl_sk);
}

static struct pernet_operations dccp_v6_ops = {
    .init   = dccp_v6_init_net,
    .exit   = dccp_v6_exit_net,
};

static int __init dccp_v6_init(void)
{
    int err = proto_register(&dccp_v6_prot, 1);

    if (err != 0)
        goto out;

    err = inet6_add_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
    if (err != 0)
        goto out_unregister_proto;

    inet6_register_protosw(&dccp_v6_protosw);

    err = register_pernet_subsys(&dccp_v6_ops);
    if (err != 0)
        goto out_destroy_ctl_sock;
out:
    return err;

out_destroy_ctl_sock:
    inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
    inet6_unregister_protosw(&dccp_v6_protosw);
out_unregister_proto:
    proto_unregister(&dccp_v6_prot);
    goto out;
}

static void __exit dccp_v6_exit(void)
{
    unregister_pernet_subsys(&dccp_v6_ops);
    inet6_del_protocol(&dccp_v6_protocol, IPPROTO_DCCP);
    inet6_unregister_protosw(&dccp_v6_protosw);
    proto_unregister(&dccp_v6_prot);
}

module_init(dccp_v6_init);
module_exit(dccp_v6_exit);

/*
 * __stringify doesn't likes enums, so use SOCK_DCCP (6) and IPPROTO_DCCP (33)
 * values directly, Also cover the case where the protocol is not specified,
 * i.e. net-pf-PF_INET6-proto-0-type-SOCK_DCCP
 */
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 33, 6);
MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 0, 6);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Arnaldo Carvalho de Melo <[email protected]>");
MODULE_DESCRIPTION("DCCPv6 - Datagram Congestion Controlled Protocol");