Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris...

[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / netfilter / nf_conntrack_l3proto_ipv6.c

/*
 * Copyright (C)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 <yasuyuki.kozakai@toshiba.co.jp>
 */

#include <linux/types.h>
#include <linux/ipv6.h>
#include <linux/in6.h>
#include <linux/netfilter.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmp.h>
#include <net/ipv6.h>
#include <net/inet_frag.h>

#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_l3proto.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
#include <net/netfilter/nf_nat_helper.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#include <net/netfilter/nf_log.h>

static bool ipv6_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
                              struct nf_conntrack_tuple *tuple)
{
        const u_int32_t *ap;
        u_int32_t _addrs[8];

        ap = skb_header_pointer(skb, nhoff + offsetof(struct ipv6hdr, saddr),
                                sizeof(_addrs), _addrs);
        if (ap == NULL)
                return false;

        memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
        memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));

        return true;
}

static bool ipv6_invert_tuple(struct nf_conntrack_tuple *tuple,
                              const struct nf_conntrack_tuple *orig)
{
        memcpy(tuple->src.u3.ip6, orig->dst.u3.ip6, sizeof(tuple->src.u3.ip6));
        memcpy(tuple->dst.u3.ip6, orig->src.u3.ip6, sizeof(tuple->dst.u3.ip6));

        return true;
}

static int ipv6_print_tuple(struct seq_file *s,
                            const struct nf_conntrack_tuple *tuple)
{
        return seq_printf(s, "src=%pI6 dst=%pI6 ",
                          tuple->src.u3.ip6, tuple->dst.u3.ip6);
}

static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
                            unsigned int *dataoff, u_int8_t *protonum)
{
        unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
        __be16 frag_off;
        int protoff;
        u8 nexthdr;

        if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
                          &nexthdr, sizeof(nexthdr)) != 0) {
                pr_debug("ip6_conntrack_core: can't get nexthdr\n");
                return -NF_ACCEPT;
        }
        protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
        /*
         * (protoff == skb->len) means the packet has not data, just
         * IPv6 and possibly extensions headers, but it is tracked anyway
         */
        if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
                pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
                return -NF_ACCEPT;
        }

        *dataoff = protoff;
        *protonum = nexthdr;
        return NF_ACCEPT;
}

static unsigned int ipv6_helper(unsigned int hooknum,
                                struct sk_buff *skb,
                                const struct net_device *in,
                                const struct net_device *out,
                                int (*okfn)(struct sk_buff *))
{
        struct nf_conn *ct;
        const struct nf_conn_help *help;
        const struct nf_conntrack_helper *helper;
        enum ip_conntrack_info ctinfo;
        __be16 frag_off;
        int protoff;
        u8 nexthdr;

        /* This is where we call the helper: as the packet goes out. */
        ct = nf_ct_get(skb, &ctinfo);
        if (!ct || ctinfo == IP_CT_RELATED_REPLY)
                return NF_ACCEPT;

        help = nfct_help(ct);
        if (!help)
                return NF_ACCEPT;
        /* rcu_read_lock()ed by nf_hook_slow */
        helper = rcu_dereference(help->helper);
        if (!helper)
                return NF_ACCEPT;

        nexthdr = ipv6_hdr(skb)->nexthdr;
        protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
                                   &frag_off);
        if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
                pr_debug("proto header not found\n");
                return NF_ACCEPT;
        }

        return helper->help(skb, protoff, ct, ctinfo);
}

static unsigned int ipv6_confirm(unsigned int hooknum,
                                 struct sk_buff *skb,
                                 const struct net_device *in,
                                 const struct net_device *out,
                                 int (*okfn)(struct sk_buff *))
{
        struct nf_conn *ct;
        enum ip_conntrack_info ctinfo;
        unsigned char pnum = ipv6_hdr(skb)->nexthdr;
        int protoff;
        __be16 frag_off;

        ct = nf_ct_get(skb, &ctinfo);
        if (!ct || ctinfo == IP_CT_RELATED_REPLY)
                goto out;

        protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
                                   &frag_off);
        if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
                pr_debug("proto header not found\n");
                goto out;
        }

        /* adjust seqs for loopback traffic only in outgoing direction */
        if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
            !nf_is_loopback_packet(skb)) {
                typeof(nf_nat_seq_adjust_hook) seq_adjust;

                seq_adjust = rcu_dereference(nf_nat_seq_adjust_hook);
                if (!seq_adjust ||
                    !seq_adjust(skb, ct, ctinfo, protoff)) {
                        NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
                        return NF_DROP;
                }
        }
out:
        /* We've seen it coming out the other side: confirm it */
        return nf_conntrack_confirm(skb);
}

static unsigned int __ipv6_conntrack_in(struct net *net,
                                        unsigned int hooknum,
                                        struct sk_buff *skb,
                                        const struct net_device *in,
                                        const struct net_device *out,
                                        int (*okfn)(struct sk_buff *))
{
        struct sk_buff *reasm = skb->nfct_reasm;
        const struct nf_conn_help *help;
        struct nf_conn *ct;
        enum ip_conntrack_info ctinfo;

        /* This packet is fragmented and has reassembled packet. */
        if (reasm) {
                /* Reassembled packet isn't parsed yet ? */
                if (!reasm->nfct) {
                        unsigned int ret;

                        ret = nf_conntrack_in(net, PF_INET6, hooknum, reasm);
                        if (ret != NF_ACCEPT)
                                return ret;
                }

                /* Conntrack helpers need the entire reassembled packet in the
                 * POST_ROUTING hook. In case of unconfirmed connections NAT
                 * might reassign a helper, so the entire packet is also
                 * required.
                 */
                ct = nf_ct_get(reasm, &ctinfo);
                if (ct != NULL && !nf_ct_is_untracked(ct)) {
                        help = nfct_help(ct);
                        if ((help && help->helper) || !nf_ct_is_confirmed(ct)) {
                                nf_conntrack_get_reasm(reasm);
                                NF_HOOK_THRESH(NFPROTO_IPV6, hooknum, reasm,
                                               (struct net_device *)in,
                                               (struct net_device *)out,
                                               okfn, NF_IP6_PRI_CONNTRACK + 1);
                                return NF_DROP_ERR(-ECANCELED);
                        }
                }

                nf_conntrack_get(reasm->nfct);
                skb->nfct = reasm->nfct;
                skb->nfctinfo = reasm->nfctinfo;
                return NF_ACCEPT;
        }

        return nf_conntrack_in(net, PF_INET6, hooknum, skb);
}

static unsigned int ipv6_conntrack_in(unsigned int hooknum,
                                      struct sk_buff *skb,
                                      const struct net_device *in,
                                      const struct net_device *out,
                                      int (*okfn)(struct sk_buff *))
{
        return __ipv6_conntrack_in(dev_net(in), hooknum, skb, in, out, okfn);
}

static unsigned int ipv6_conntrack_local(unsigned int hooknum,
                                         struct sk_buff *skb,
                                         const struct net_device *in,
                                         const struct net_device *out,
                                         int (*okfn)(struct sk_buff *))
{
        /* root is playing with raw sockets. */
        if (skb->len < sizeof(struct ipv6hdr)) {
                net_notice_ratelimited("ipv6_conntrack_local: packet too short\n");
                return NF_ACCEPT;
        }
        return __ipv6_conntrack_in(dev_net(out), hooknum, skb, in, out, okfn);
}

static struct nf_hook_ops ipv6_conntrack_ops[] __read_mostly = {
        {
                .hook           = ipv6_conntrack_in,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_PRE_ROUTING,
                .priority       = NF_IP6_PRI_CONNTRACK,
        },
        {
                .hook           = ipv6_conntrack_local,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_LOCAL_OUT,
                .priority       = NF_IP6_PRI_CONNTRACK,
        },
        {
                .hook           = ipv6_helper,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_POST_ROUTING,
                .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
        },
        {
                .hook           = ipv6_confirm,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_POST_ROUTING,
                .priority       = NF_IP6_PRI_LAST,
        },
        {
                .hook           = ipv6_helper,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_LOCAL_IN,
                .priority       = NF_IP6_PRI_CONNTRACK_HELPER,
        },
        {
                .hook           = ipv6_confirm,
                .owner          = THIS_MODULE,
                .pf             = NFPROTO_IPV6,
                .hooknum        = NF_INET_LOCAL_IN,
                .priority       = NF_IP6_PRI_LAST-1,
        },
};

static int
ipv6_getorigdst(struct sock *sk, int optval, void __user *user, int *len)
{
        const struct inet_sock *inet = inet_sk(sk);
        const struct ipv6_pinfo *inet6 = inet6_sk(sk);
        const struct nf_conntrack_tuple_hash *h;
        struct sockaddr_in6 sin6;
        struct nf_conntrack_tuple tuple = { .src.l3num = NFPROTO_IPV6 };
        struct nf_conn *ct;

        tuple.src.u3.in6 = inet6->rcv_saddr;
        tuple.src.u.tcp.port = inet->inet_sport;
        tuple.dst.u3.in6 = inet6->daddr;
        tuple.dst.u.tcp.port = inet->inet_dport;
        tuple.dst.protonum = sk->sk_protocol;

        if (sk->sk_protocol != IPPROTO_TCP && sk->sk_protocol != IPPROTO_SCTP)
                return -ENOPROTOOPT;

        if (*len < 0 || (unsigned int) *len < sizeof(sin6))
                return -EINVAL;

        h = nf_conntrack_find_get(sock_net(sk), NF_CT_DEFAULT_ZONE, &tuple);
        if (!h) {
                pr_debug("IP6T_SO_ORIGINAL_DST: Can't find %pI6c/%u-%pI6c/%u.\n",
                         &tuple.src.u3.ip6, ntohs(tuple.src.u.tcp.port),
                         &tuple.dst.u3.ip6, ntohs(tuple.dst.u.tcp.port));
                return -ENOENT;
        }

        ct = nf_ct_tuplehash_to_ctrack(h);

        sin6.sin6_family = AF_INET6;
        sin6.sin6_port = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.tcp.port;
        sin6.sin6_flowinfo = inet6->flow_label & IPV6_FLOWINFO_MASK;
        memcpy(&sin6.sin6_addr,
                &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.in6,
                                        sizeof(sin6.sin6_addr));

        nf_ct_put(ct);
        sin6.sin6_scope_id = ipv6_iface_scope_id(&sin6.sin6_addr,
                                                 sk->sk_bound_dev_if);
        return copy_to_user(user, &sin6, sizeof(sin6)) ? -EFAULT : 0;
}

#if IS_ENABLED(CONFIG_NF_CT_NETLINK)

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

static int ipv6_tuple_to_nlattr(struct sk_buff *skb,
                                const struct nf_conntrack_tuple *tuple)
{
        if (nla_put(skb, CTA_IP_V6_SRC, sizeof(u_int32_t) * 4,
                    &tuple->src.u3.ip6) ||
            nla_put(skb, CTA_IP_V6_DST, sizeof(u_int32_t) * 4,
                    &tuple->dst.u3.ip6))
                goto nla_put_failure;
        return 0;

nla_put_failure:
        return -1;
}

static const struct nla_policy ipv6_nla_policy[CTA_IP_MAX+1] = {
        [CTA_IP_V6_SRC] = { .len = sizeof(u_int32_t)*4 },
        [CTA_IP_V6_DST] = { .len = sizeof(u_int32_t)*4 },
};

static int ipv6_nlattr_to_tuple(struct nlattr *tb[],
                                struct nf_conntrack_tuple *t)
{
        if (!tb[CTA_IP_V6_SRC] || !tb[CTA_IP_V6_DST])
                return -EINVAL;

        memcpy(&t->src.u3.ip6, nla_data(tb[CTA_IP_V6_SRC]),
               sizeof(u_int32_t) * 4);
        memcpy(&t->dst.u3.ip6, nla_data(tb[CTA_IP_V6_DST]),
               sizeof(u_int32_t) * 4);

        return 0;
}

static int ipv6_nlattr_tuple_size(void)
{
        return nla_policy_len(ipv6_nla_policy, CTA_IP_MAX + 1);
}
#endif

struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 __read_mostly = {
        .l3proto                = PF_INET6,
        .name                   = "ipv6",
        .pkt_to_tuple           = ipv6_pkt_to_tuple,
        .invert_tuple           = ipv6_invert_tuple,
        .print_tuple            = ipv6_print_tuple,
        .get_l4proto            = ipv6_get_l4proto,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
        .tuple_to_nlattr        = ipv6_tuple_to_nlattr,
        .nlattr_tuple_size      = ipv6_nlattr_tuple_size,
        .nlattr_to_tuple        = ipv6_nlattr_to_tuple,
        .nla_policy             = ipv6_nla_policy,
#endif
        .me                     = THIS_MODULE,
};

MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET6));
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yasuyuki KOZAKAI @USAGI <yasuyuki.kozakai@toshiba.co.jp>");

static struct nf_sockopt_ops so_getorigdst6 = {
        .pf             = NFPROTO_IPV6,
        .get_optmin     = IP6T_SO_ORIGINAL_DST,
        .get_optmax     = IP6T_SO_ORIGINAL_DST + 1,
        .get            = ipv6_getorigdst,
        .owner          = THIS_MODULE,
};

static int ipv6_net_init(struct net *net)
{
        int ret = 0;

        ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_tcp6);
        if (ret < 0) {
                pr_err("nf_conntrack_tcp6: pernet registration failed\n");
                goto out;
        }
        ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_udp6);
        if (ret < 0) {
                pr_err("nf_conntrack_udp6: pernet registration failed\n");
                goto cleanup_tcp6;
        }
        ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_icmpv6);
        if (ret < 0) {
                pr_err("nf_conntrack_icmp6: pernet registration failed\n");
                goto cleanup_udp6;
        }
        ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv6);
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: pernet registration failed.\n");
                goto cleanup_icmpv6;
        }
        return 0;
 cleanup_icmpv6:
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
 cleanup_udp6:
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
 cleanup_tcp6:
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
 out:
        return ret;
}

static void ipv6_net_exit(struct net *net)
{
        nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv6);
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmpv6);
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp6);
        nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp6);
}

static struct pernet_operations ipv6_net_ops = {
        .init = ipv6_net_init,
        .exit = ipv6_net_exit,
};

static int __init nf_conntrack_l3proto_ipv6_init(void)
{
        int ret = 0;

        need_conntrack();
        nf_defrag_ipv6_enable();

        ret = nf_register_sockopt(&so_getorigdst6);
        if (ret < 0) {
                pr_err("Unable to register netfilter socket option\n");
                return ret;
        }

        ret = register_pernet_subsys(&ipv6_net_ops);
        if (ret < 0)
                goto cleanup_sockopt;

        ret = nf_register_hooks(ipv6_conntrack_ops,
                                ARRAY_SIZE(ipv6_conntrack_ops));
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: can't register pre-routing defrag "
                       "hook.\n");
                goto cleanup_pernet;
        }

        ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_tcp6);
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: can't register tcp6 proto.\n");
                goto cleanup_hooks;
        }

        ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_udp6);
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: can't register udp6 proto.\n");
                goto cleanup_tcp6;
        }

        ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_icmpv6);
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: can't register icmpv6 proto.\n");
                goto cleanup_udp6;
        }

        ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv6);
        if (ret < 0) {
                pr_err("nf_conntrack_ipv6: can't register ipv6 proto.\n");
                goto cleanup_icmpv6;
        }
        return ret;

 cleanup_icmpv6:
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
 cleanup_udp6:
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
 cleanup_tcp6:
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
 cleanup_hooks:
        nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
 cleanup_pernet:
        unregister_pernet_subsys(&ipv6_net_ops);
 cleanup_sockopt:
        nf_unregister_sockopt(&so_getorigdst6);
        return ret;
}

static void __exit nf_conntrack_l3proto_ipv6_fini(void)
{
        synchronize_net();
        nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv6);
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp6);
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp6);
        nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmpv6);
        nf_unregister_hooks(ipv6_conntrack_ops, ARRAY_SIZE(ipv6_conntrack_ops));
        unregister_pernet_subsys(&ipv6_net_ops);
        nf_unregister_sockopt(&so_getorigdst6);
}

module_init(nf_conntrack_l3proto_ipv6_init);
module_exit(nf_conntrack_l3proto_ipv6_fini);