nf_conntrack_proto_icmpv6.c

Go to the documentation of this file.

/*
 * Copyright (C)2003,2004 USAGI/WIDE Project
 *
 * 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.
 *
 * Author:
 *  Yasuyuki Kozakai @USAGI <[email protected]>
 */

#include <linux/types.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/in6.h>
#include <linux/icmpv6.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include <net/ip6_checksum.h>
#include <linux/seq_file.h>
#include <linux/netfilter_ipv6.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
#include <net/netfilter/nf_log.h>

static unsigned int nf_ct_icmpv6_timeout __read_mostly = 30*HZ;

static inline struct nf_icmp_net *icmpv6_pernet(struct net *net)
{
    return &net->ct.nf_ct_proto.icmpv6;
}

static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
                unsigned int dataoff,
                struct nf_conntrack_tuple *tuple)
{
    const struct icmp6hdr *hp;
    struct icmp6hdr _hdr;

    hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
    if (hp == NULL)
        return false;
    tuple->dst.u.icmp.type = hp->icmp6_type;
    tuple->src.u.icmp.id = hp->icmp6_identifier;
    tuple->dst.u.icmp.code = hp->icmp6_code;

    return true;
}

/* Add 1; spaces filled with 0. */
static const u_int8_t invmap[] = {
    [ICMPV6_ECHO_REQUEST - 128] = ICMPV6_ECHO_REPLY + 1,
    [ICMPV6_ECHO_REPLY - 128]   = ICMPV6_ECHO_REQUEST + 1,
    [ICMPV6_NI_QUERY - 128]     = ICMPV6_NI_REPLY + 1,
    [ICMPV6_NI_REPLY - 128]     = ICMPV6_NI_QUERY +1
};

static const u_int8_t noct_valid_new[] = {
    [ICMPV6_MGM_QUERY - 130] = 1,
    [ICMPV6_MGM_REPORT -130] = 1,
    [ICMPV6_MGM_REDUCTION - 130] = 1,
    [NDISC_ROUTER_SOLICITATION - 130] = 1,
    [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
    [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
    [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
    [ICMPV6_MLD2_REPORT - 130] = 1
};

static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
                const struct nf_conntrack_tuple *orig)
{
    int type = orig->dst.u.icmp.type - 128;
    if (type < 0 || type >= sizeof(invmap) || !invmap[type])
        return false;

    tuple->src.u.icmp.id   = orig->src.u.icmp.id;
    tuple->dst.u.icmp.type = invmap[type] - 1;
    tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
    return true;
}

/* Print out the per-protocol part of the tuple. */
static int icmpv6_print_tuple(struct seq_file *s,
                  const struct nf_conntrack_tuple *tuple)
{
    return seq_printf(s, "type=%u code=%u id=%u ",
              tuple->dst.u.icmp.type,
              tuple->dst.u.icmp.code,
              ntohs(tuple->src.u.icmp.id));
}

static unsigned int *icmpv6_get_timeouts(struct net *net)
{
    return &icmpv6_pernet(net)->timeout;
}

/* Returns verdict for packet, or -1 for invalid. */
static int icmpv6_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 *timeout)
{
    /* Do not immediately delete the connection after the first
       successful reply to avoid excessive conntrackd traffic
       and also to handle correctly ICMP echo reply duplicates. */
    nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);

    return NF_ACCEPT;
}

/* Called when a new connection for this protocol found. */
static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
               unsigned int dataoff, unsigned int *timeouts)
{
    static const u_int8_t valid_new[] = {
        [ICMPV6_ECHO_REQUEST - 128] = 1,
        [ICMPV6_NI_QUERY - 128] = 1
    };
    int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;

    if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
        /* Can't create a new ICMPv6 `conn' with this. */
        pr_debug("icmpv6: can't create new conn with type %u\n",
             type + 128);
        nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
        if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
            nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
                      "nf_ct_icmpv6: invalid new with type %d ",
                      type + 128);
        return false;
    }
    return true;
}

static int
icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
             struct sk_buff *skb,
             unsigned int icmp6off,
             enum ip_conntrack_info *ctinfo,
             unsigned int hooknum)
{
    struct nf_conntrack_tuple intuple, origtuple;
    const struct nf_conntrack_tuple_hash *h;
    const struct nf_conntrack_l4proto *inproto;
    u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;

    NF_CT_ASSERT(skb->nfct == NULL);

    /* Are they talking about one of our connections? */
    if (!nf_ct_get_tuplepr(skb,
                   skb_network_offset(skb)
                + sizeof(struct ipv6hdr)
                + sizeof(struct icmp6hdr),
                   PF_INET6, &origtuple)) {
        pr_debug("icmpv6_error: Can't get tuple\n");
        return -NF_ACCEPT;
    }

    /* rcu_read_lock()ed by nf_hook_slow */
    inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);

    /* Ordinarily, we'd expect the inverted tupleproto, but it's
       been preserved inside the ICMP. */
    if (!nf_ct_invert_tuple(&intuple, &origtuple,
                &nf_conntrack_l3proto_ipv6, inproto)) {
        pr_debug("icmpv6_error: Can't invert tuple\n");
        return -NF_ACCEPT;
    }

    *ctinfo = IP_CT_RELATED;

    h = nf_conntrack_find_get(net, zone, &intuple);
    if (!h) {
        pr_debug("icmpv6_error: no match\n");
        return -NF_ACCEPT;
    } else {
        if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
            *ctinfo += IP_CT_IS_REPLY;
    }

    /* Update skb to refer to this connection */
    skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
    skb->nfctinfo = *ctinfo;
    return NF_ACCEPT;
}

static int
icmpv6_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)
{
    const struct icmp6hdr *icmp6h;
    struct icmp6hdr _ih;
    int type;

    icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
    if (icmp6h == NULL) {
        if (LOG_INVALID(net, IPPROTO_ICMPV6))
        nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
                  "nf_ct_icmpv6: short packet ");
        return -NF_ACCEPT;
    }

    if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
        nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
        if (LOG_INVALID(net, IPPROTO_ICMPV6))
            nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
                      "nf_ct_icmpv6: ICMPv6 checksum failed ");
        return -NF_ACCEPT;
    }

    type = icmp6h->icmp6_type - 130;
    if (type >= 0 && type < sizeof(noct_valid_new) &&
        noct_valid_new[type]) {
        skb->nfct = &nf_ct_untracked_get()->ct_general;
        skb->nfctinfo = IP_CT_NEW;
        nf_conntrack_get(skb->nfct);
        return NF_ACCEPT;
    }

    /* is not error message ? */
    if (icmp6h->icmp6_type >= 128)
        return NF_ACCEPT;

    return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
}

#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>
static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
                  const struct nf_conntrack_tuple *t)
{
    if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
        nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
        nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -1;
}

static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
    [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
    [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
    [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
};

static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
                struct nf_conntrack_tuple *tuple)
{
    if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
        !tb[CTA_PROTO_ICMPV6_CODE] ||
        !tb[CTA_PROTO_ICMPV6_ID])
        return -EINVAL;

    tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
    tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
    tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);

    if (tuple->dst.u.icmp.type < 128 ||
        tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
        !invmap[tuple->dst.u.icmp.type - 128])
        return -EINVAL;

    return 0;
}

static int icmpv6_nlattr_tuple_size(void)
{
    return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
}
#endif

#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)

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

static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
                    struct net *net, void *data)
{
    unsigned int *timeout = data;
    struct nf_icmp_net *in = icmpv6_pernet(net);

    if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
        *timeout =
            ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
    } else {
        /* Set default ICMPv6 timeout. */
        *timeout = in->timeout;
    }
    return 0;
}

static int
icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
{
    const unsigned int *timeout = data;

    if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -ENOSPC;
}

static const struct nla_policy
icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
    [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
};
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */

#ifdef CONFIG_SYSCTL
static struct ctl_table icmpv6_sysctl_table[] = {
    {
        .procname   = "nf_conntrack_icmpv6_timeout",
        .maxlen     = sizeof(unsigned int),
        .mode       = 0644,
        .proc_handler   = proc_dointvec_jiffies,
    },
    { }
};
#endif /* CONFIG_SYSCTL */

static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
                       struct nf_icmp_net *in)
{
#ifdef CONFIG_SYSCTL
    pn->ctl_table = kmemdup(icmpv6_sysctl_table,
                sizeof(icmpv6_sysctl_table),
                GFP_KERNEL);
    if (!pn->ctl_table)
        return -ENOMEM;

    pn->ctl_table[0].data = &in->timeout;
#endif
    return 0;
}

static int icmpv6_init_net(struct net *net, u_int16_t proto)
{
    struct nf_icmp_net *in = icmpv6_pernet(net);
    struct nf_proto_net *pn = &in->pn;

    in->timeout = nf_ct_icmpv6_timeout;

    return icmpv6_kmemdup_sysctl_table(pn, in);
}

static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
{
    return &net->ct.nf_ct_proto.icmpv6.pn;
}

struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
{
    .l3proto        = PF_INET6,
    .l4proto        = IPPROTO_ICMPV6,
    .name           = "icmpv6",
    .pkt_to_tuple       = icmpv6_pkt_to_tuple,
    .invert_tuple       = icmpv6_invert_tuple,
    .print_tuple        = icmpv6_print_tuple,
    .packet         = icmpv6_packet,
    .get_timeouts       = icmpv6_get_timeouts,
    .new            = icmpv6_new,
    .error          = icmpv6_error,
#if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
    .tuple_to_nlattr    = icmpv6_tuple_to_nlattr,
    .nlattr_tuple_size  = icmpv6_nlattr_tuple_size,
    .nlattr_to_tuple    = icmpv6_nlattr_to_tuple,
    .nla_policy     = icmpv6_nla_policy,
#endif
#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
    .ctnl_timeout       = {
        .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
        .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
        .nlattr_max = CTA_TIMEOUT_ICMP_MAX,
        .obj_size   = sizeof(unsigned int),
        .nla_policy = icmpv6_timeout_nla_policy,
    },
#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
    .init_net       = icmpv6_init_net,
    .get_net_proto      = icmpv6_get_net_proto,
};