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- /* (C) 1999-2001 Paul `Rusty' Russell
- * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
- * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
- *
- * 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/types.h>
- #include <linux/ip.h>
- #include <linux/netfilter.h>
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/icmp.h>
- #include <linux/sysctl.h>
- #include <net/route.h>
- #include <net/ip.h>
- #include <linux/netfilter_ipv4.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_zones.h>
- #include <net/netfilter/nf_conntrack_core.h>
- #include <net/netfilter/nf_conntrack_seqadj.h>
- #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
- #include <net/netfilter/nf_nat_helper.h>
- #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
- #include <net/netfilter/nf_log.h>
- static bool ipv4_pkt_to_tuple(const struct sk_buff *skb, unsigned int nhoff,
- struct nf_conntrack_tuple *tuple)
- {
- const __be32 *ap;
- __be32 _addrs[2];
- ap = skb_header_pointer(skb, nhoff + offsetof(struct iphdr, saddr),
- sizeof(u_int32_t) * 2, _addrs);
- if (ap == NULL)
- return false;
- tuple->src.u3.ip = ap[0];
- tuple->dst.u3.ip = ap[1];
- return true;
- }
- static bool ipv4_invert_tuple(struct nf_conntrack_tuple *tuple,
- const struct nf_conntrack_tuple *orig)
- {
- tuple->src.u3.ip = orig->dst.u3.ip;
- tuple->dst.u3.ip = orig->src.u3.ip;
- return true;
- }
- static void ipv4_print_tuple(struct seq_file *s,
- const struct nf_conntrack_tuple *tuple)
- {
- seq_printf(s, "src=%pI4 dst=%pI4 ",
- &tuple->src.u3.ip, &tuple->dst.u3.ip);
- }
- static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
- unsigned int *dataoff, u_int8_t *protonum)
- {
- const struct iphdr *iph;
- struct iphdr _iph;
- iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
- if (iph == NULL)
- return -NF_ACCEPT;
- /* Conntrack defragments packets, we might still see fragments
- * inside ICMP packets though. */
- if (iph->frag_off & htons(IP_OFFSET))
- return -NF_ACCEPT;
- *dataoff = nhoff + (iph->ihl << 2);
- *protonum = iph->protocol;
- /* Check bogus IP headers */
- if (*dataoff > skb->len) {
- pr_debug("nf_conntrack_ipv4: bogus IPv4 packet: "
- "nhoff %u, ihl %u, skblen %u\n",
- nhoff, iph->ihl << 2, skb->len);
- return -NF_ACCEPT;
- }
- return NF_ACCEPT;
- }
- static unsigned int ipv4_helper(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- const struct nf_conn_help *help;
- const struct nf_conntrack_helper *helper;
- /* 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;
- return helper->help(skb, skb_network_offset(skb) + ip_hdrlen(skb),
- ct, ctinfo);
- }
- static unsigned int ipv4_confirm(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- struct nf_conn *ct;
- enum ip_conntrack_info ctinfo;
- ct = nf_ct_get(skb, &ctinfo);
- if (!ct || ctinfo == IP_CT_RELATED_REPLY)
- 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)) {
- if (!nf_ct_seq_adjust(skb, ct, ctinfo, ip_hdrlen(skb))) {
- 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 ipv4_conntrack_in(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
- }
- static unsigned int ipv4_conntrack_local(void *priv,
- struct sk_buff *skb,
- const struct nf_hook_state *state)
- {
- /* root is playing with raw sockets. */
- if (skb->len < sizeof(struct iphdr) ||
- ip_hdrlen(skb) < sizeof(struct iphdr))
- return NF_ACCEPT;
- if (ip_is_fragment(ip_hdr(skb))) /* IP_NODEFRAG setsockopt set */
- return NF_ACCEPT;
- return nf_conntrack_in(state->net, PF_INET, state->hook, skb);
- }
- /* Connection tracking may drop packets, but never alters them, so
- make it the first hook. */
- static struct nf_hook_ops ipv4_conntrack_ops[] __read_mostly = {
- {
- .hook = ipv4_conntrack_in,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_PRE_ROUTING,
- .priority = NF_IP_PRI_CONNTRACK,
- },
- {
- .hook = ipv4_conntrack_local,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_LOCAL_OUT,
- .priority = NF_IP_PRI_CONNTRACK,
- },
- {
- .hook = ipv4_helper,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_POST_ROUTING,
- .priority = NF_IP_PRI_CONNTRACK_HELPER,
- },
- {
- .hook = ipv4_confirm,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_POST_ROUTING,
- .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
- },
- {
- .hook = ipv4_helper,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_LOCAL_IN,
- .priority = NF_IP_PRI_CONNTRACK_HELPER,
- },
- {
- .hook = ipv4_confirm,
- .pf = NFPROTO_IPV4,
- .hooknum = NF_INET_LOCAL_IN,
- .priority = NF_IP_PRI_CONNTRACK_CONFIRM,
- },
- };
- #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- static int log_invalid_proto_min = 0;
- static int log_invalid_proto_max = 255;
- static struct ctl_table ip_ct_sysctl_table[] = {
- {
- .procname = "ip_conntrack_max",
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "ip_conntrack_count",
- .maxlen = sizeof(int),
- .mode = 0444,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "ip_conntrack_buckets",
- .maxlen = sizeof(unsigned int),
- .mode = 0444,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "ip_conntrack_checksum",
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec,
- },
- {
- .procname = "ip_conntrack_log_invalid",
- .maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &log_invalid_proto_min,
- .extra2 = &log_invalid_proto_max,
- },
- { }
- };
- #endif /* CONFIG_SYSCTL && CONFIG_NF_CONNTRACK_PROC_COMPAT */
- /* Fast function for those who don't want to parse /proc (and I don't
- blame them). */
- /* Reversing the socket's dst/src point of view gives us the reply
- mapping. */
- static int
- getorigdst(struct sock *sk, int optval, void __user *user, int *len)
- {
- const struct inet_sock *inet = inet_sk(sk);
- const struct nf_conntrack_tuple_hash *h;
- struct nf_conntrack_tuple tuple;
- memset(&tuple, 0, sizeof(tuple));
- lock_sock(sk);
- tuple.src.u3.ip = inet->inet_rcv_saddr;
- tuple.src.u.tcp.port = inet->inet_sport;
- tuple.dst.u3.ip = inet->inet_daddr;
- tuple.dst.u.tcp.port = inet->inet_dport;
- tuple.src.l3num = PF_INET;
- tuple.dst.protonum = sk->sk_protocol;
- release_sock(sk);
- /* We only do TCP and SCTP at the moment: is there a better way? */
- if (tuple.dst.protonum != IPPROTO_TCP &&
- tuple.dst.protonum != IPPROTO_SCTP) {
- pr_debug("SO_ORIGINAL_DST: Not a TCP/SCTP socket\n");
- return -ENOPROTOOPT;
- }
- if ((unsigned int) *len < sizeof(struct sockaddr_in)) {
- pr_debug("SO_ORIGINAL_DST: len %d not %Zu\n",
- *len, sizeof(struct sockaddr_in));
- return -EINVAL;
- }
- h = nf_conntrack_find_get(sock_net(sk), &nf_ct_zone_dflt, &tuple);
- if (h) {
- struct sockaddr_in sin;
- struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
- sin.sin_family = AF_INET;
- sin.sin_port = ct->tuplehash[IP_CT_DIR_ORIGINAL]
- .tuple.dst.u.tcp.port;
- sin.sin_addr.s_addr = ct->tuplehash[IP_CT_DIR_ORIGINAL]
- .tuple.dst.u3.ip;
- memset(sin.sin_zero, 0, sizeof(sin.sin_zero));
- pr_debug("SO_ORIGINAL_DST: %pI4 %u\n",
- &sin.sin_addr.s_addr, ntohs(sin.sin_port));
- nf_ct_put(ct);
- if (copy_to_user(user, &sin, sizeof(sin)) != 0)
- return -EFAULT;
- else
- return 0;
- }
- pr_debug("SO_ORIGINAL_DST: Can't find %pI4/%u-%pI4/%u.\n",
- &tuple.src.u3.ip, ntohs(tuple.src.u.tcp.port),
- &tuple.dst.u3.ip, ntohs(tuple.dst.u.tcp.port));
- return -ENOENT;
- }
- #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
- #include <linux/netfilter/nfnetlink.h>
- #include <linux/netfilter/nfnetlink_conntrack.h>
- static int ipv4_tuple_to_nlattr(struct sk_buff *skb,
- const struct nf_conntrack_tuple *tuple)
- {
- if (nla_put_in_addr(skb, CTA_IP_V4_SRC, tuple->src.u3.ip) ||
- nla_put_in_addr(skb, CTA_IP_V4_DST, tuple->dst.u3.ip))
- goto nla_put_failure;
- return 0;
- nla_put_failure:
- return -1;
- }
- static const struct nla_policy ipv4_nla_policy[CTA_IP_MAX+1] = {
- [CTA_IP_V4_SRC] = { .type = NLA_U32 },
- [CTA_IP_V4_DST] = { .type = NLA_U32 },
- };
- static int ipv4_nlattr_to_tuple(struct nlattr *tb[],
- struct nf_conntrack_tuple *t)
- {
- if (!tb[CTA_IP_V4_SRC] || !tb[CTA_IP_V4_DST])
- return -EINVAL;
- t->src.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_SRC]);
- t->dst.u3.ip = nla_get_in_addr(tb[CTA_IP_V4_DST]);
- return 0;
- }
- static int ipv4_nlattr_tuple_size(void)
- {
- return nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1);
- }
- #endif
- static struct nf_sockopt_ops so_getorigdst = {
- .pf = PF_INET,
- .get_optmin = SO_ORIGINAL_DST,
- .get_optmax = SO_ORIGINAL_DST+1,
- .get = getorigdst,
- .owner = THIS_MODULE,
- };
- static int ipv4_init_net(struct net *net)
- {
- #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- struct nf_ip_net *in = &net->ct.nf_ct_proto;
- in->ctl_table = kmemdup(ip_ct_sysctl_table,
- sizeof(ip_ct_sysctl_table),
- GFP_KERNEL);
- if (!in->ctl_table)
- return -ENOMEM;
- in->ctl_table[0].data = &nf_conntrack_max;
- in->ctl_table[1].data = &net->ct.count;
- in->ctl_table[2].data = &net->ct.htable_size;
- in->ctl_table[3].data = &net->ct.sysctl_checksum;
- in->ctl_table[4].data = &net->ct.sysctl_log_invalid;
- #endif
- return 0;
- }
- struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 __read_mostly = {
- .l3proto = PF_INET,
- .name = "ipv4",
- .pkt_to_tuple = ipv4_pkt_to_tuple,
- .invert_tuple = ipv4_invert_tuple,
- .print_tuple = ipv4_print_tuple,
- .get_l4proto = ipv4_get_l4proto,
- #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
- .tuple_to_nlattr = ipv4_tuple_to_nlattr,
- .nlattr_tuple_size = ipv4_nlattr_tuple_size,
- .nlattr_to_tuple = ipv4_nlattr_to_tuple,
- .nla_policy = ipv4_nla_policy,
- #endif
- #if defined(CONFIG_SYSCTL) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- .ctl_table_path = "net/ipv4/netfilter",
- #endif
- .init_net = ipv4_init_net,
- .me = THIS_MODULE,
- };
- module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
- &nf_conntrack_htable_size, 0600);
- MODULE_ALIAS("nf_conntrack-" __stringify(AF_INET));
- MODULE_ALIAS("ip_conntrack");
- MODULE_LICENSE("GPL");
- static int ipv4_net_init(struct net *net)
- {
- int ret = 0;
- ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_tcp4);
- if (ret < 0) {
- pr_err("nf_conntrack_tcp4: pernet registration failed\n");
- goto out_tcp;
- }
- ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_udp4);
- if (ret < 0) {
- pr_err("nf_conntrack_udp4: pernet registration failed\n");
- goto out_udp;
- }
- ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_icmp);
- if (ret < 0) {
- pr_err("nf_conntrack_icmp4: pernet registration failed\n");
- goto out_icmp;
- }
- ret = nf_ct_l3proto_pernet_register(net, &nf_conntrack_l3proto_ipv4);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: pernet registration failed\n");
- goto out_ipv4;
- }
- return 0;
- out_ipv4:
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmp);
- out_icmp:
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp4);
- out_udp:
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp4);
- out_tcp:
- return ret;
- }
- static void ipv4_net_exit(struct net *net)
- {
- nf_ct_l3proto_pernet_unregister(net, &nf_conntrack_l3proto_ipv4);
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_icmp);
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_udp4);
- nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_tcp4);
- }
- static struct pernet_operations ipv4_net_ops = {
- .init = ipv4_net_init,
- .exit = ipv4_net_exit,
- };
- static int __init nf_conntrack_l3proto_ipv4_init(void)
- {
- int ret = 0;
- need_conntrack();
- nf_defrag_ipv4_enable();
- ret = nf_register_sockopt(&so_getorigdst);
- if (ret < 0) {
- printk(KERN_ERR "Unable to register netfilter socket option\n");
- return ret;
- }
- ret = register_pernet_subsys(&ipv4_net_ops);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register pernet ops\n");
- goto cleanup_sockopt;
- }
- ret = nf_register_hooks(ipv4_conntrack_ops,
- ARRAY_SIZE(ipv4_conntrack_ops));
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register hooks.\n");
- goto cleanup_pernet;
- }
- ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_tcp4);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register tcp4 proto.\n");
- goto cleanup_hooks;
- }
- ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_udp4);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register udp4 proto.\n");
- goto cleanup_tcp4;
- }
- ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_icmp);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register icmpv4 proto.\n");
- goto cleanup_udp4;
- }
- ret = nf_ct_l3proto_register(&nf_conntrack_l3proto_ipv4);
- if (ret < 0) {
- pr_err("nf_conntrack_ipv4: can't register ipv4 proto.\n");
- goto cleanup_icmpv4;
- }
- #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- ret = nf_conntrack_ipv4_compat_init();
- if (ret < 0)
- goto cleanup_proto;
- #endif
- return ret;
- #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- cleanup_proto:
- nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
- #endif
- cleanup_icmpv4:
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmp);
- cleanup_udp4:
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp4);
- cleanup_tcp4:
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
- cleanup_hooks:
- nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
- cleanup_pernet:
- unregister_pernet_subsys(&ipv4_net_ops);
- cleanup_sockopt:
- nf_unregister_sockopt(&so_getorigdst);
- return ret;
- }
- static void __exit nf_conntrack_l3proto_ipv4_fini(void)
- {
- synchronize_net();
- #if defined(CONFIG_PROC_FS) && defined(CONFIG_NF_CONNTRACK_PROC_COMPAT)
- nf_conntrack_ipv4_compat_fini();
- #endif
- nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4);
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_icmp);
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_udp4);
- nf_ct_l4proto_unregister(&nf_conntrack_l4proto_tcp4);
- nf_unregister_hooks(ipv4_conntrack_ops, ARRAY_SIZE(ipv4_conntrack_ops));
- unregister_pernet_subsys(&ipv4_net_ops);
- nf_unregister_sockopt(&so_getorigdst);
- }
- module_init(nf_conntrack_l3proto_ipv4_init);
- module_exit(nf_conntrack_l3proto_ipv4_fini);
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