nf_conntrack_proto_dccp.c

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/*
 * DCCP connection tracking protocol helper
 *
 * Copyright (c) 2005, 2006, 2008 Patrick McHardy <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/dccp.h>
#include <linux/slab.h>

#include <net/net_namespace.h>
#include <net/netns/generic.h>

#include <linux/netfilter/nfnetlink_conntrack.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_log.h>

/* Timeouts are based on values from RFC4340:
 *
 * - REQUEST:
 *
 *   8.1.2. Client Request
 *
 *   A client MAY give up on its DCCP-Requests after some time
 *   (3 minutes, for example).
 *
 * - RESPOND:
 *
 *   8.1.3. Server Response
 *
 *   It MAY also leave the RESPOND state for CLOSED after a timeout of
 *   not less than 4MSL (8 minutes);
 *
 * - PARTOPEN:
 *
 *   8.1.5. Handshake Completion
 *
 *   If the client remains in PARTOPEN for more than 4MSL (8 minutes),
 *   it SHOULD reset the connection with Reset Code 2, "Aborted".
 *
 * - OPEN:
 *
 *   The DCCP timestamp overflows after 11.9 hours. If the connection
 *   stays idle this long the sequence number won't be recognized
 *   as valid anymore.
 *
 * - CLOSEREQ/CLOSING:
 *
 *   8.3. Termination
 *
 *   The retransmission timer should initially be set to go off in two
 *   round-trip times and should back off to not less than once every
 *   64 seconds ...
 *
 * - TIMEWAIT:
 *
 *   4.3. States
 *
 *   A server or client socket remains in this state for 2MSL (4 minutes)
 *   after the connection has been town down, ...
 */

#define DCCP_MSL (2 * 60 * HZ)

static const char * const dccp_state_names[] = {
    [CT_DCCP_NONE]      = "NONE",
    [CT_DCCP_REQUEST]   = "REQUEST",
    [CT_DCCP_RESPOND]   = "RESPOND",
    [CT_DCCP_PARTOPEN]  = "PARTOPEN",
    [CT_DCCP_OPEN]      = "OPEN",
    [CT_DCCP_CLOSEREQ]  = "CLOSEREQ",
    [CT_DCCP_CLOSING]   = "CLOSING",
    [CT_DCCP_TIMEWAIT]  = "TIMEWAIT",
    [CT_DCCP_IGNORE]    = "IGNORE",
    [CT_DCCP_INVALID]   = "INVALID",
};

#define sNO CT_DCCP_NONE
#define sRQ CT_DCCP_REQUEST
#define sRS CT_DCCP_RESPOND
#define sPO CT_DCCP_PARTOPEN
#define sOP CT_DCCP_OPEN
#define sCR CT_DCCP_CLOSEREQ
#define sCG CT_DCCP_CLOSING
#define sTW CT_DCCP_TIMEWAIT
#define sIG CT_DCCP_IGNORE
#define sIV CT_DCCP_INVALID

/*
 * DCCP state transition table
 *
 * The assumption is the same as for TCP tracking:
 *
 * We are the man in the middle. All the packets go through us but might
 * get lost in transit to the destination. It is assumed that the destination
 * can't receive segments we haven't seen.
 *
 * The following states exist:
 *
 * NONE:    Initial state, expecting Request
 * REQUEST: Request seen, waiting for Response from server
 * RESPOND: Response from server seen, waiting for Ack from client
 * PARTOPEN:    Ack after Response seen, waiting for packet other than Response,
 *      Reset or Sync from server
 * OPEN:    Packet other than Response, Reset or Sync seen
 * CLOSEREQ:    CloseReq from server seen, expecting Close from client
 * CLOSING: Close seen, expecting Reset
 * TIMEWAIT:    Reset seen
 * IGNORE:  Not determinable whether packet is valid
 *
 * Some states exist only on one side of the connection: REQUEST, RESPOND,
 * PARTOPEN, CLOSEREQ. For the other side these states are equivalent to
 * the one it was in before.
 *
 * Packets are marked as ignored (sIG) if we don't know if they're valid
 * (for example a reincarnation of a connection we didn't notice is dead
 * already) and the server may send back a connection closing Reset or a
 * Response. They're also used for Sync/SyncAck packets, which we don't
 * care about.
 */
static const u_int8_t
dccp_state_table[CT_DCCP_ROLE_MAX + 1][DCCP_PKT_SYNCACK + 1][CT_DCCP_MAX + 1] = {
    [CT_DCCP_ROLE_CLIENT] = {
        [DCCP_PKT_REQUEST] = {
        /*
         * sNO -> sRQ       Regular Request
         * sRQ -> sRQ       Retransmitted Request or reincarnation
         * sRS -> sRS       Retransmitted Request (apparently Response
         *          got lost after we saw it) or reincarnation
         * sPO -> sIG       Ignore, conntrack might be out of sync
         * sOP -> sIG       Ignore, conntrack might be out of sync
         * sCR -> sIG       Ignore, conntrack might be out of sync
         * sCG -> sIG       Ignore, conntrack might be out of sync
         * sTW -> sRQ       Reincarnation
         *
         *  sNO, sRQ, sRS, sPO. sOP, sCR, sCG, sTW, */
            sRQ, sRQ, sRS, sIG, sIG, sIG, sIG, sRQ,
        },
        [DCCP_PKT_RESPONSE] = {
        /*
         * sNO -> sIV       Invalid
         * sRQ -> sIG       Ignore, might be response to ignored Request
         * sRS -> sIG       Ignore, might be response to ignored Request
         * sPO -> sIG       Ignore, might be response to ignored Request
         * sOP -> sIG       Ignore, might be response to ignored Request
         * sCR -> sIG       Ignore, might be response to ignored Request
         * sCG -> sIG       Ignore, might be response to ignored Request
         * sTW -> sIV       Invalid, reincarnation in reverse direction
         *          goes through sRQ
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIV,
        },
        [DCCP_PKT_ACK] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sPO       Ack for Response, move to PARTOPEN (8.1.5.)
         * sPO -> sPO       Retransmitted Ack for Response, remain in PARTOPEN
         * sOP -> sOP       Regular ACK, remain in OPEN
         * sCR -> sCR       Ack in CLOSEREQ MAY be processed (8.3.)
         * sCG -> sCG       Ack in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
        },
        [DCCP_PKT_DATA] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sIV       MUST use DataAck in PARTOPEN state (8.1.5.)
         * sOP -> sOP       Regular Data packet
         * sCR -> sCR       Data in CLOSEREQ MAY be processed (8.3.)
         * sCG -> sCG       Data in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sIV, sOP, sCR, sCG, sIV,
        },
        [DCCP_PKT_DATAACK] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sPO       Ack for Response, move to PARTOPEN (8.1.5.)
         * sPO -> sPO       Remain in PARTOPEN state
         * sOP -> sOP       Regular DataAck packet in OPEN state
         * sCR -> sCR       DataAck in CLOSEREQ MAY be processed (8.3.)
         * sCG -> sCG       DataAck in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sPO, sPO, sOP, sCR, sCG, sIV
        },
        [DCCP_PKT_CLOSEREQ] = {
        /*
         * CLOSEREQ may only be sent by the server.
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sIV, sIV, sIV, sIV, sIV
        },
        [DCCP_PKT_CLOSE] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sCG       Client-initiated close
         * sOP -> sCG       Client-initiated close
         * sCR -> sCG       Close in response to CloseReq (8.3.)
         * sCG -> sCG       Retransmit
         * sTW -> sIV       Late retransmit, already in TIME_WAIT
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sCG, sCG, sCG, sIV, sIV
        },
        [DCCP_PKT_RESET] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sTW       Sync received or timeout, SHOULD send Reset (8.1.1.)
         * sRS -> sTW       Response received without Request
         * sPO -> sTW       Timeout, SHOULD send Reset (8.1.5.)
         * sOP -> sTW       Connection reset
         * sCR -> sTW       Connection reset
         * sCG -> sTW       Connection reset
         * sTW -> sIG       Ignore (don't refresh timer)
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sTW, sTW, sTW, sTW, sTW, sTW, sIG
        },
        [DCCP_PKT_SYNC] = {
        /*
         * We currently ignore Sync packets
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
        },
        [DCCP_PKT_SYNCACK] = {
        /*
         * We currently ignore SyncAck packets
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
        },
    },
    [CT_DCCP_ROLE_SERVER] = {
        [DCCP_PKT_REQUEST] = {
        /*
         * sNO -> sIV       Invalid
         * sRQ -> sIG       Ignore, conntrack might be out of sync
         * sRS -> sIG       Ignore, conntrack might be out of sync
         * sPO -> sIG       Ignore, conntrack might be out of sync
         * sOP -> sIG       Ignore, conntrack might be out of sync
         * sCR -> sIG       Ignore, conntrack might be out of sync
         * sCG -> sIG       Ignore, conntrack might be out of sync
         * sTW -> sRQ       Reincarnation, must reverse roles
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIG, sIG, sIG, sIG, sIG, sIG, sRQ
        },
        [DCCP_PKT_RESPONSE] = {
        /*
         * sNO -> sIV       Response without Request
         * sRQ -> sRS       Response to clients Request
         * sRS -> sRS       Retransmitted Response (8.1.3. SHOULD NOT)
         * sPO -> sIG       Response to an ignored Request or late retransmit
         * sOP -> sIG       Ignore, might be response to ignored Request
         * sCR -> sIG       Ignore, might be response to ignored Request
         * sCG -> sIG       Ignore, might be response to ignored Request
         * sTW -> sIV       Invalid, Request from client in sTW moves to sRQ
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sRS, sRS, sIG, sIG, sIG, sIG, sIV
        },
        [DCCP_PKT_ACK] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sOP       Enter OPEN state (8.1.5.)
         * sOP -> sOP       Regular Ack in OPEN state
         * sCR -> sIV       Waiting for Close from client
         * sCG -> sCG       Ack in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
        },
        [DCCP_PKT_DATA] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sOP       Enter OPEN state (8.1.5.)
         * sOP -> sOP       Regular Data packet in OPEN state
         * sCR -> sIV       Waiting for Close from client
         * sCG -> sCG       Data in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
        },
        [DCCP_PKT_DATAACK] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sOP       Enter OPEN state (8.1.5.)
         * sOP -> sOP       Regular DataAck in OPEN state
         * sCR -> sIV       Waiting for Close from client
         * sCG -> sCG       Data in CLOSING MAY be processed (8.3.)
         * sTW -> sIV
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sOP, sOP, sIV, sCG, sIV
        },
        [DCCP_PKT_CLOSEREQ] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sOP -> sCR    Move directly to CLOSEREQ (8.1.5.)
         * sOP -> sCR       CloseReq in OPEN state
         * sCR -> sCR       Retransmit
         * sCG -> sCR       Simultaneous close, client sends another Close
         * sTW -> sIV       Already closed
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sCR, sCR, sCR, sCR, sIV
        },
        [DCCP_PKT_CLOSE] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sIV       No connection
         * sRS -> sIV       No connection
         * sPO -> sOP -> sCG    Move direcly to CLOSING
         * sOP -> sCG       Move to CLOSING
         * sCR -> sIV       Close after CloseReq is invalid
         * sCG -> sCG       Retransmit
         * sTW -> sIV       Already closed
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIV, sIV, sIV, sCG, sCG, sIV, sCG, sIV
        },
        [DCCP_PKT_RESET] = {
        /*
         * sNO -> sIV       No connection
         * sRQ -> sTW       Reset in response to Request
         * sRS -> sTW       Timeout, SHOULD send Reset (8.1.3.)
         * sPO -> sTW       Timeout, SHOULD send Reset (8.1.3.)
         * sOP -> sTW
         * sCR -> sTW
         * sCG -> sTW
         * sTW -> sIG       Ignore (don't refresh timer)
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW, sTW */
            sIV, sTW, sTW, sTW, sTW, sTW, sTW, sTW, sIG
        },
        [DCCP_PKT_SYNC] = {
        /*
         * We currently ignore Sync packets
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
        },
        [DCCP_PKT_SYNCACK] = {
        /*
         * We currently ignore SyncAck packets
         *
         *  sNO, sRQ, sRS, sPO, sOP, sCR, sCG, sTW */
            sIG, sIG, sIG, sIG, sIG, sIG, sIG, sIG,
        },
    },
};

/* this module per-net specifics */
static int dccp_net_id __read_mostly;
struct dccp_net {
    struct nf_proto_net pn;
    int dccp_loose;
    unsigned int dccp_timeout[CT_DCCP_MAX + 1];
};

static inline struct dccp_net *dccp_pernet(struct net *net)
{
    return net_generic(net, dccp_net_id);
}

static bool dccp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
                  struct nf_conntrack_tuple *tuple)
{
    struct dccp_hdr _hdr, *dh;

    dh = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
    if (dh == NULL)
        return false;

    tuple->src.u.dccp.port = dh->dccph_sport;
    tuple->dst.u.dccp.port = dh->dccph_dport;
    return true;
}

static bool dccp_invert_tuple(struct nf_conntrack_tuple *inv,
                  const struct nf_conntrack_tuple *tuple)
{
    inv->src.u.dccp.port = tuple->dst.u.dccp.port;
    inv->dst.u.dccp.port = tuple->src.u.dccp.port;
    return true;
}

static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
             unsigned int dataoff, unsigned int *timeouts)
{
    struct net *net = nf_ct_net(ct);
    struct dccp_net *dn;
    struct dccp_hdr _dh, *dh;
    const char *msg;
    u_int8_t state;

    dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
    BUG_ON(dh == NULL);

    state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
    switch (state) {
    default:
        dn = dccp_pernet(net);
        if (dn->dccp_loose == 0) {
            msg = "nf_ct_dccp: not picking up existing connection ";
            goto out_invalid;
        }
    case CT_DCCP_REQUEST:
        break;
    case CT_DCCP_INVALID:
        msg = "nf_ct_dccp: invalid state transition ";
        goto out_invalid;
    }

    ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
    ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
    ct->proto.dccp.state = CT_DCCP_NONE;
    ct->proto.dccp.last_pkt = DCCP_PKT_REQUEST;
    ct->proto.dccp.last_dir = IP_CT_DIR_ORIGINAL;
    ct->proto.dccp.handshake_seq = 0;
    return true;

out_invalid:
    if (LOG_INVALID(net, IPPROTO_DCCP))
        nf_log_packet(nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL, msg);
    return false;
}

static u64 dccp_ack_seq(const struct dccp_hdr *dh)
{
    const struct dccp_hdr_ack_bits *dhack;

    dhack = (void *)dh + __dccp_basic_hdr_len(dh);
    return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) +
             ntohl(dhack->dccph_ack_nr_low);
}

static unsigned int *dccp_get_timeouts(struct net *net)
{
    return dccp_pernet(net)->dccp_timeout;
}

static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
               unsigned int dataoff, enum ip_conntrack_info ctinfo,
               u_int8_t pf, unsigned int hooknum,
               unsigned int *timeouts)
{
    struct net *net = nf_ct_net(ct);
    enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
    struct dccp_hdr _dh, *dh;
    u_int8_t type, old_state, new_state;
    enum ct_dccp_roles role;

    dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
    BUG_ON(dh == NULL);
    type = dh->dccph_type;

    if (type == DCCP_PKT_RESET &&
        !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
        /* Tear down connection immediately if only reply is a RESET */
        nf_ct_kill_acct(ct, ctinfo, skb);
        return NF_ACCEPT;
    }

    spin_lock_bh(&ct->lock);

    role = ct->proto.dccp.role[dir];
    old_state = ct->proto.dccp.state;
    new_state = dccp_state_table[role][type][old_state];

    switch (new_state) {
    case CT_DCCP_REQUEST:
        if (old_state == CT_DCCP_TIMEWAIT &&
            role == CT_DCCP_ROLE_SERVER) {
            /* Reincarnation in the reverse direction: reopen and
             * reverse client/server roles. */
            ct->proto.dccp.role[dir] = CT_DCCP_ROLE_CLIENT;
            ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_SERVER;
        }
        break;
    case CT_DCCP_RESPOND:
        if (old_state == CT_DCCP_REQUEST)
            ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
        break;
    case CT_DCCP_PARTOPEN:
        if (old_state == CT_DCCP_RESPOND &&
            type == DCCP_PKT_ACK &&
            dccp_ack_seq(dh) == ct->proto.dccp.handshake_seq)
            set_bit(IPS_ASSURED_BIT, &ct->status);
        break;
    case CT_DCCP_IGNORE:
        /*
         * Connection tracking might be out of sync, so we ignore
         * packets that might establish a new connection and resync
         * if the server responds with a valid Response.
         */
        if (ct->proto.dccp.last_dir == !dir &&
            ct->proto.dccp.last_pkt == DCCP_PKT_REQUEST &&
            type == DCCP_PKT_RESPONSE) {
            ct->proto.dccp.role[!dir] = CT_DCCP_ROLE_CLIENT;
            ct->proto.dccp.role[dir] = CT_DCCP_ROLE_SERVER;
            ct->proto.dccp.handshake_seq = dccp_hdr_seq(dh);
            new_state = CT_DCCP_RESPOND;
            break;
        }
        ct->proto.dccp.last_dir = dir;
        ct->proto.dccp.last_pkt = type;

        spin_unlock_bh(&ct->lock);
        if (LOG_INVALID(net, IPPROTO_DCCP))
            nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
                      "nf_ct_dccp: invalid packet ignored ");
        return NF_ACCEPT;
    case CT_DCCP_INVALID:
        spin_unlock_bh(&ct->lock);
        if (LOG_INVALID(net, IPPROTO_DCCP))
            nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
                      "nf_ct_dccp: invalid state transition ");
        return -NF_ACCEPT;
    }

    ct->proto.dccp.last_dir = dir;
    ct->proto.dccp.last_pkt = type;
    ct->proto.dccp.state = new_state;
    spin_unlock_bh(&ct->lock);

    if (new_state != old_state)
        nf_conntrack_event_cache(IPCT_PROTOINFO, ct);

    nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[new_state]);

    return NF_ACCEPT;
}

static int dccp_error(struct net *net, struct nf_conn *tmpl,
              struct sk_buff *skb, unsigned int dataoff,
              enum ip_conntrack_info *ctinfo,
              u_int8_t pf, unsigned int hooknum)
{
    struct dccp_hdr _dh, *dh;
    unsigned int dccp_len = skb->len - dataoff;
    unsigned int cscov;
    const char *msg;

    dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
    if (dh == NULL) {
        msg = "nf_ct_dccp: short packet ";
        goto out_invalid;
    }

    if (dh->dccph_doff * 4 < sizeof(struct dccp_hdr) ||
        dh->dccph_doff * 4 > dccp_len) {
        msg = "nf_ct_dccp: truncated/malformed packet ";
        goto out_invalid;
    }

    cscov = dccp_len;
    if (dh->dccph_cscov) {
        cscov = (dh->dccph_cscov - 1) * 4;
        if (cscov > dccp_len) {
            msg = "nf_ct_dccp: bad checksum coverage ";
            goto out_invalid;
        }
    }

    if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
        nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_DCCP,
                pf)) {
        msg = "nf_ct_dccp: bad checksum ";
        goto out_invalid;
    }

    if (dh->dccph_type >= DCCP_PKT_INVALID) {
        msg = "nf_ct_dccp: reserved packet type ";
        goto out_invalid;
    }

    return NF_ACCEPT;

out_invalid:
    if (LOG_INVALID(net, IPPROTO_DCCP))
        nf_log_packet(pf, 0, skb, NULL, NULL, NULL, msg);
    return -NF_ACCEPT;
}

static int dccp_print_tuple(struct seq_file *s,
                const struct nf_conntrack_tuple *tuple)
{
    return seq_printf(s, "sport=%hu dport=%hu ",
              ntohs(tuple->src.u.dccp.port),
              ntohs(tuple->dst.u.dccp.port));
}

static int dccp_print_conntrack(struct seq_file *s, struct nf_conn *ct)
{
    return seq_printf(s, "%s ", dccp_state_names[ct->proto.dccp.state]);
}

#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
static int dccp_to_nlattr(struct sk_buff *skb, struct nlattr *nla,
              struct nf_conn *ct)
{
    struct nlattr *nest_parms;

    spin_lock_bh(&ct->lock);
    nest_parms = nla_nest_start(skb, CTA_PROTOINFO_DCCP | NLA_F_NESTED);
    if (!nest_parms)
        goto nla_put_failure;
    if (nla_put_u8(skb, CTA_PROTOINFO_DCCP_STATE, ct->proto.dccp.state) ||
        nla_put_u8(skb, CTA_PROTOINFO_DCCP_ROLE,
               ct->proto.dccp.role[IP_CT_DIR_ORIGINAL]) ||
        nla_put_be64(skb, CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ,
             cpu_to_be64(ct->proto.dccp.handshake_seq)))
        goto nla_put_failure;
    nla_nest_end(skb, nest_parms);
    spin_unlock_bh(&ct->lock);
    return 0;

nla_put_failure:
    spin_unlock_bh(&ct->lock);
    return -1;
}

static const struct nla_policy dccp_nla_policy[CTA_PROTOINFO_DCCP_MAX + 1] = {
    [CTA_PROTOINFO_DCCP_STATE]  = { .type = NLA_U8 },
    [CTA_PROTOINFO_DCCP_ROLE]   = { .type = NLA_U8 },
    [CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ] = { .type = NLA_U64 },
};

static int nlattr_to_dccp(struct nlattr *cda[], struct nf_conn *ct)
{
    struct nlattr *attr = cda[CTA_PROTOINFO_DCCP];
    struct nlattr *tb[CTA_PROTOINFO_DCCP_MAX + 1];
    int err;

    if (!attr)
        return 0;

    err = nla_parse_nested(tb, CTA_PROTOINFO_DCCP_MAX, attr,
                   dccp_nla_policy);
    if (err < 0)
        return err;

    if (!tb[CTA_PROTOINFO_DCCP_STATE] ||
        !tb[CTA_PROTOINFO_DCCP_ROLE] ||
        nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) > CT_DCCP_ROLE_MAX ||
        nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]) >= CT_DCCP_IGNORE) {
        return -EINVAL;
    }

    spin_lock_bh(&ct->lock);
    ct->proto.dccp.state = nla_get_u8(tb[CTA_PROTOINFO_DCCP_STATE]);
    if (nla_get_u8(tb[CTA_PROTOINFO_DCCP_ROLE]) == CT_DCCP_ROLE_CLIENT) {
        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_CLIENT;
        ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_SERVER;
    } else {
        ct->proto.dccp.role[IP_CT_DIR_ORIGINAL] = CT_DCCP_ROLE_SERVER;
        ct->proto.dccp.role[IP_CT_DIR_REPLY] = CT_DCCP_ROLE_CLIENT;
    }
    if (tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]) {
        ct->proto.dccp.handshake_seq =
        be64_to_cpu(nla_get_be64(tb[CTA_PROTOINFO_DCCP_HANDSHAKE_SEQ]));
    }
    spin_unlock_bh(&ct->lock);
    return 0;
}

static int dccp_nlattr_size(void)
{
    return nla_total_size(0)    /* CTA_PROTOINFO_DCCP */
        + nla_policy_len(dccp_nla_policy, CTA_PROTOINFO_DCCP_MAX + 1);
}

#endif

#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_cttimeout.h>

static int dccp_timeout_nlattr_to_obj(struct nlattr *tb[],
                      struct net *net, void *data)
{
    struct dccp_net *dn = dccp_pernet(net);
    unsigned int *timeouts = data;
    int i;

    /* set default DCCP timeouts. */
    for (i=0; i<CT_DCCP_MAX; i++)
        timeouts[i] = dn->dccp_timeout[i];

    /* there's a 1:1 mapping between attributes and protocol states. */
    for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
        if (tb[i]) {
            timeouts[i] = ntohl(nla_get_be32(tb[i])) * HZ;
        }
    }
    return 0;
}

static int
dccp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
{
        const unsigned int *timeouts = data;
    int i;

    for (i=CTA_TIMEOUT_DCCP_UNSPEC+1; i<CTA_TIMEOUT_DCCP_MAX+1; i++) {
        if (nla_put_be32(skb, i, htonl(timeouts[i] / HZ)))
            goto nla_put_failure;
    }
    return 0;

nla_put_failure:
    return -ENOSPC;
}

static const struct nla_policy
dccp_timeout_nla_policy[CTA_TIMEOUT_DCCP_MAX+1] = {
    [CTA_TIMEOUT_DCCP_REQUEST]  = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_RESPOND]  = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_PARTOPEN] = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_OPEN]     = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_CLOSEREQ] = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_CLOSING]  = { .type = NLA_U32 },
    [CTA_TIMEOUT_DCCP_TIMEWAIT] = { .type = NLA_U32 },
};
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */

#ifdef CONFIG_SYSCTL
/* template, data assigned later */
static struct ctl_table dccp_sysctl_table[] = {
    {
        .procname   = "nf_conntrack_dccp_timeout_request",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_respond",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_partopen",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_open",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_closereq",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_closing",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_timeout_timewait",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    {
        .procname   = "nf_conntrack_dccp_loose",
        .maxlen     = sizeof(int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec,
    },
    { }
};
#endif /* CONFIG_SYSCTL */

static int dccp_kmemdup_sysctl_table(struct nf_proto_net *pn,
                     struct dccp_net *dn)
{
#ifdef CONFIG_SYSCTL
    if (pn->ctl_table)
        return 0;

    pn->ctl_table = kmemdup(dccp_sysctl_table,
                sizeof(dccp_sysctl_table),
                GFP_KERNEL);
    if (!pn->ctl_table)
        return -ENOMEM;

    pn->ctl_table[0].data = &dn->dccp_timeout[CT_DCCP_REQUEST];
    pn->ctl_table[1].data = &dn->dccp_timeout[CT_DCCP_RESPOND];
    pn->ctl_table[2].data = &dn->dccp_timeout[CT_DCCP_PARTOPEN];
    pn->ctl_table[3].data = &dn->dccp_timeout[CT_DCCP_OPEN];
    pn->ctl_table[4].data = &dn->dccp_timeout[CT_DCCP_CLOSEREQ];
    pn->ctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
    pn->ctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
    pn->ctl_table[7].data = &dn->dccp_loose;
#endif
    return 0;
}

static int dccp_init_net(struct net *net, u_int16_t proto)
{
    struct dccp_net *dn = dccp_pernet(net);
    struct nf_proto_net *pn = &dn->pn;

    if (!pn->users) {
        /* default values */
        dn->dccp_loose = 1;
        dn->dccp_timeout[CT_DCCP_REQUEST]   = 2 * DCCP_MSL;
        dn->dccp_timeout[CT_DCCP_RESPOND]   = 4 * DCCP_MSL;
        dn->dccp_timeout[CT_DCCP_PARTOPEN]  = 4 * DCCP_MSL;
        dn->dccp_timeout[CT_DCCP_OPEN]      = 12 * 3600 * HZ;
        dn->dccp_timeout[CT_DCCP_CLOSEREQ]  = 64 * HZ;
        dn->dccp_timeout[CT_DCCP_CLOSING]   = 64 * HZ;
        dn->dccp_timeout[CT_DCCP_TIMEWAIT]  = 2 * DCCP_MSL;
    }

    return dccp_kmemdup_sysctl_table(pn, dn);
}

static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
    .l3proto        = AF_INET,
    .l4proto        = IPPROTO_DCCP,
    .name           = "dccp",
    .pkt_to_tuple       = dccp_pkt_to_tuple,
    .invert_tuple       = dccp_invert_tuple,
    .new            = dccp_new,
    .packet         = dccp_packet,
    .get_timeouts       = dccp_get_timeouts,
    .error          = dccp_error,
    .print_tuple        = dccp_print_tuple,
    .print_conntrack    = dccp_print_conntrack,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
    .to_nlattr      = dccp_to_nlattr,
    .nlattr_size        = dccp_nlattr_size,
    .from_nlattr        = nlattr_to_dccp,
    .tuple_to_nlattr    = nf_ct_port_tuple_to_nlattr,
    .nlattr_tuple_size  = nf_ct_port_nlattr_tuple_size,
    .nlattr_to_tuple    = nf_ct_port_nlattr_to_tuple,
    .nla_policy     = nf_ct_port_nla_policy,
#endif
#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
    .ctnl_timeout       = {
        .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
        .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
        .nlattr_max = CTA_TIMEOUT_DCCP_MAX,
        .obj_size   = sizeof(unsigned int) * CT_DCCP_MAX,
        .nla_policy = dccp_timeout_nla_policy,
    },
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
    .net_id         = &dccp_net_id,
    .init_net       = dccp_init_net,
};

static struct nf_conntrack_l4proto dccp_proto6 __read_mostly = {
    .l3proto        = AF_INET6,
    .l4proto        = IPPROTO_DCCP,
    .name           = "dccp",
    .pkt_to_tuple       = dccp_pkt_to_tuple,
    .invert_tuple       = dccp_invert_tuple,
    .new            = dccp_new,
    .packet         = dccp_packet,
    .get_timeouts       = dccp_get_timeouts,
    .error          = dccp_error,
    .print_tuple        = dccp_print_tuple,
    .print_conntrack    = dccp_print_conntrack,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
    .to_nlattr      = dccp_to_nlattr,
    .nlattr_size        = dccp_nlattr_size,
    .from_nlattr        = nlattr_to_dccp,
    .tuple_to_nlattr    = nf_ct_port_tuple_to_nlattr,
    .nlattr_tuple_size  = nf_ct_port_nlattr_tuple_size,
    .nlattr_to_tuple    = nf_ct_port_nlattr_to_tuple,
    .nla_policy     = nf_ct_port_nla_policy,
#endif
#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
    .ctnl_timeout       = {
        .nlattr_to_obj  = dccp_timeout_nlattr_to_obj,
        .obj_to_nlattr  = dccp_timeout_obj_to_nlattr,
        .nlattr_max = CTA_TIMEOUT_DCCP_MAX,
        .obj_size   = sizeof(unsigned int) * CT_DCCP_MAX,
        .nla_policy = dccp_timeout_nla_policy,
    },
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
    .net_id         = &dccp_net_id,
    .init_net       = dccp_init_net,
};

static __net_init int dccp_net_init(struct net *net)
{
    int ret = 0;
    ret = nf_conntrack_l4proto_register(net,
                        &dccp_proto4);
    if (ret < 0) {
        pr_err("nf_conntrack_l4proto_dccp4 :protocol register failed.\n");
        goto out;
    }
    ret = nf_conntrack_l4proto_register(net,
                        &dccp_proto6);
    if (ret < 0) {
        pr_err("nf_conntrack_l4proto_dccp6 :protocol register failed.\n");
        goto cleanup_dccp4;
    }
    return 0;
cleanup_dccp4:
    nf_conntrack_l4proto_unregister(net,
                    &dccp_proto4);
out:
    return ret;
}

static __net_exit void dccp_net_exit(struct net *net)
{
    nf_conntrack_l4proto_unregister(net,
                    &dccp_proto6);
    nf_conntrack_l4proto_unregister(net,
                    &dccp_proto4);
}

static struct pernet_operations dccp_net_ops = {
    .init = dccp_net_init,
    .exit = dccp_net_exit,
    .id   = &dccp_net_id,
    .size = sizeof(struct dccp_net),
};

static int __init nf_conntrack_proto_dccp_init(void)
{
    return register_pernet_subsys(&dccp_net_ops);
}

static void __exit nf_conntrack_proto_dccp_fini(void)
{
    unregister_pernet_subsys(&dccp_net_ops);
}

module_init(nf_conntrack_proto_dccp_init);
module_exit(nf_conntrack_proto_dccp_fini);

MODULE_AUTHOR("Patrick McHardy <[email protected]>");
MODULE_DESCRIPTION("DCCP connection tracking protocol helper");
MODULE_LICENSE("GPL");