| |
| /* (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 int conntrack4_net_id __read_mostly; |
| static DEFINE_MUTEX(register_ipv4_hooks); |
| |
| struct conntrack4_net { |
| unsigned int users; |
| }; |
| |
| 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 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_thresh */ |
| 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) |
| { |
| if (ip_is_fragment(ip_hdr(skb))) { /* IP_NODEFRAG setsockopt set */ |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *tmpl; |
| |
| tmpl = nf_ct_get(skb, &ctinfo); |
| if (tmpl && nf_ct_is_template(tmpl)) { |
| /* when skipping ct, clear templates to avoid fooling |
| * later targets/matches |
| */ |
| skb->_nfct = 0; |
| nf_ct_put(tmpl); |
| } |
| 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 const struct nf_hook_ops ipv4_conntrack_ops[] = { |
| { |
| .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, |
| }, |
| }; |
| |
| /* 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; |
| } |
| #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_hooks_register(struct net *net) |
| { |
| struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id); |
| int err = 0; |
| |
| mutex_lock(®ister_ipv4_hooks); |
| |
| cnet->users++; |
| if (cnet->users > 1) |
| goto out_unlock; |
| |
| err = nf_defrag_ipv4_enable(net); |
| if (err) { |
| cnet->users = 0; |
| goto out_unlock; |
| } |
| |
| err = nf_register_net_hooks(net, ipv4_conntrack_ops, |
| ARRAY_SIZE(ipv4_conntrack_ops)); |
| |
| if (err) |
| cnet->users = 0; |
| out_unlock: |
| mutex_unlock(®ister_ipv4_hooks); |
| return err; |
| } |
| |
| static void ipv4_hooks_unregister(struct net *net) |
| { |
| struct conntrack4_net *cnet = net_generic(net, conntrack4_net_id); |
| |
| mutex_lock(®ister_ipv4_hooks); |
| if (cnet->users && (--cnet->users == 0)) |
| nf_unregister_net_hooks(net, ipv4_conntrack_ops, |
| ARRAY_SIZE(ipv4_conntrack_ops)); |
| mutex_unlock(®ister_ipv4_hooks); |
| } |
| |
| const struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4 = { |
| .l3proto = PF_INET, |
| .pkt_to_tuple = ipv4_pkt_to_tuple, |
| .invert_tuple = ipv4_invert_tuple, |
| .get_l4proto = ipv4_get_l4proto, |
| #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
| .tuple_to_nlattr = ipv4_tuple_to_nlattr, |
| .nlattr_to_tuple = ipv4_nlattr_to_tuple, |
| .nla_policy = ipv4_nla_policy, |
| .nla_size = NLA_ALIGN(NLA_HDRLEN + sizeof(u32)) + /* CTA_IP_V4_SRC */ |
| NLA_ALIGN(NLA_HDRLEN + sizeof(u32)), /* CTA_IP_V4_DST */ |
| #endif |
| .net_ns_get = ipv4_hooks_register, |
| .net_ns_put = ipv4_hooks_unregister, |
| .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 const struct nf_conntrack_l4proto * const builtin_l4proto4[] = { |
| &nf_conntrack_l4proto_tcp4, |
| &nf_conntrack_l4proto_udp4, |
| &nf_conntrack_l4proto_icmp, |
| #ifdef CONFIG_NF_CT_PROTO_DCCP |
| &nf_conntrack_l4proto_dccp4, |
| #endif |
| #ifdef CONFIG_NF_CT_PROTO_SCTP |
| &nf_conntrack_l4proto_sctp4, |
| #endif |
| #ifdef CONFIG_NF_CT_PROTO_UDPLITE |
| &nf_conntrack_l4proto_udplite4, |
| #endif |
| }; |
| |
| static int ipv4_net_init(struct net *net) |
| { |
| return nf_ct_l4proto_pernet_register(net, builtin_l4proto4, |
| ARRAY_SIZE(builtin_l4proto4)); |
| } |
| |
| static void ipv4_net_exit(struct net *net) |
| { |
| nf_ct_l4proto_pernet_unregister(net, builtin_l4proto4, |
| ARRAY_SIZE(builtin_l4proto4)); |
| } |
| |
| static struct pernet_operations ipv4_net_ops = { |
| .init = ipv4_net_init, |
| .exit = ipv4_net_exit, |
| .id = &conntrack4_net_id, |
| .size = sizeof(struct conntrack4_net), |
| }; |
| |
| static int __init nf_conntrack_l3proto_ipv4_init(void) |
| { |
| int ret = 0; |
| |
| need_conntrack(); |
| |
| #if IS_ENABLED(CONFIG_NF_CT_NETLINK) |
| if (WARN_ON(nla_policy_len(ipv4_nla_policy, CTA_IP_MAX + 1) != |
| nf_conntrack_l3proto_ipv4.nla_size)) |
| return -EINVAL; |
| #endif |
| ret = nf_register_sockopt(&so_getorigdst); |
| if (ret < 0) { |
| pr_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_ct_l4proto_register(builtin_l4proto4, |
| ARRAY_SIZE(builtin_l4proto4)); |
| if (ret < 0) |
| goto cleanup_pernet; |
| |
| 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_l4proto; |
| } |
| |
| return ret; |
| cleanup_l4proto: |
| nf_ct_l4proto_unregister(builtin_l4proto4, |
| ARRAY_SIZE(builtin_l4proto4)); |
| 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(); |
| nf_ct_l3proto_unregister(&nf_conntrack_l3proto_ipv4); |
| nf_ct_l4proto_unregister(builtin_l4proto4, |
| ARRAY_SIZE(builtin_l4proto4)); |
| 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); |