forked from Minki/linux
netfilter: synproxy: extract SYNPROXY infrastructure from {ipt, ip6t}_SYNPROXY
Add common functions into nf_synproxy_core.c to prepare for nftables support.
The prototypes of the functions used by {ipt, ip6t}_SYNPROXY are in the new
file nf_synproxy.h
Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Fernando Fernandez Mancera
Pablo Neira Ayuso
parent
3006a5224f
commit
d7f9b2f18e
@ -72,21 +72,12 @@ struct synproxy_options {
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};
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struct tcphdr;
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struct xt_synproxy_info;
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struct nf_synproxy_info;
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bool synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
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const struct tcphdr *th,
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struct synproxy_options *opts);
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unsigned int synproxy_options_size(const struct synproxy_options *opts);
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void synproxy_build_options(struct tcphdr *th,
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const struct synproxy_options *opts);
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void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
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void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
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struct synproxy_options *opts);
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void synproxy_check_timestamp_cookie(struct synproxy_options *opts);
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unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
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struct tcphdr *th, struct nf_conn *ct,
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enum ip_conntrack_info ctinfo,
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const struct nf_conn_synproxy *synproxy);
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#endif /* _NF_CONNTRACK_SYNPROXY_H */
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44
include/net/netfilter/nf_synproxy.h
Normal file
44
include/net/netfilter/nf_synproxy.h
Normal file
@ -0,0 +1,44 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _NF_SYNPROXY_SHARED_H
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#define _NF_SYNPROXY_SHARED_H
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/ip6_checksum.h>
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#include <net/ip6_route.h>
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#include <net/tcp.h>
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#include <net/netfilter/nf_conntrack_seqadj.h>
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#include <net/netfilter/nf_conntrack_synproxy.h>
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void synproxy_send_client_synack(struct net *net, const struct sk_buff *skb,
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const struct tcphdr *th,
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const struct synproxy_options *opts);
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bool synproxy_recv_client_ack(struct net *net,
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const struct sk_buff *skb,
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const struct tcphdr *th,
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struct synproxy_options *opts, u32 recv_seq);
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unsigned int ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *nhs);
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int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net);
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void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net);
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#if IS_ENABLED(CONFIG_IPV6)
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void synproxy_send_client_synack_ipv6(struct net *net,
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const struct sk_buff *skb,
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const struct tcphdr *th,
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const struct synproxy_options *opts);
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bool synproxy_recv_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
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const struct tcphdr *th,
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struct synproxy_options *opts, u32 recv_seq);
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unsigned int ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *nhs);
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int nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net);
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void nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net);
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#endif /* CONFIG_IPV6 */
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#endif /* _NF_SYNPROXY_SHARED_H */
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@ -6,258 +6,11 @@
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <net/tcp.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_SYNPROXY.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_seqadj.h>
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#include <net/netfilter/nf_conntrack_synproxy.h>
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#include <net/netfilter/nf_conntrack_ecache.h>
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static struct iphdr *
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synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
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__be32 daddr)
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{
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struct iphdr *iph;
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skb_reset_network_header(skb);
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iph = skb_put(skb, sizeof(*iph));
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iph->version = 4;
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iph->ihl = sizeof(*iph) / 4;
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iph->tos = 0;
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iph->id = 0;
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iph->frag_off = htons(IP_DF);
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iph->ttl = net->ipv4.sysctl_ip_default_ttl;
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iph->protocol = IPPROTO_TCP;
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iph->check = 0;
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iph->saddr = saddr;
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iph->daddr = daddr;
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return iph;
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}
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static void
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synproxy_send_tcp(struct net *net,
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const struct sk_buff *skb, struct sk_buff *nskb,
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struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
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struct iphdr *niph, struct tcphdr *nth,
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unsigned int tcp_hdr_size)
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{
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nth->check = ~tcp_v4_check(tcp_hdr_size, niph->saddr, niph->daddr, 0);
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nskb->ip_summed = CHECKSUM_PARTIAL;
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nskb->csum_start = (unsigned char *)nth - nskb->head;
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nskb->csum_offset = offsetof(struct tcphdr, check);
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skb_dst_set_noref(nskb, skb_dst(skb));
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nskb->protocol = htons(ETH_P_IP);
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if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
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goto free_nskb;
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if (nfct) {
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nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
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nf_conntrack_get(nfct);
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}
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ip_local_out(net, nskb->sk, nskb);
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return;
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free_nskb:
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kfree_skb(nskb);
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}
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static void
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synproxy_send_client_synack(struct net *net,
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const struct sk_buff *skb, const struct tcphdr *th,
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const struct synproxy_options *opts)
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{
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struct sk_buff *nskb;
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struct iphdr *iph, *niph;
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struct tcphdr *nth;
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unsigned int tcp_hdr_size;
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u16 mss = opts->mss;
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iph = ip_hdr(skb);
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tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
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nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
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GFP_ATOMIC);
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if (nskb == NULL)
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return;
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skb_reserve(nskb, MAX_TCP_HEADER);
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niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
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skb_reset_transport_header(nskb);
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nth = skb_put(nskb, tcp_hdr_size);
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nth->source = th->dest;
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nth->dest = th->source;
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nth->seq = htonl(__cookie_v4_init_sequence(iph, th, &mss));
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nth->ack_seq = htonl(ntohl(th->seq) + 1);
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tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
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if (opts->options & XT_SYNPROXY_OPT_ECN)
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tcp_flag_word(nth) |= TCP_FLAG_ECE;
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nth->doff = tcp_hdr_size / 4;
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nth->window = 0;
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nth->check = 0;
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nth->urg_ptr = 0;
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synproxy_build_options(nth, opts);
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synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
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IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
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}
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static void
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synproxy_send_server_syn(struct net *net,
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const struct sk_buff *skb, const struct tcphdr *th,
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const struct synproxy_options *opts, u32 recv_seq)
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{
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struct synproxy_net *snet = synproxy_pernet(net);
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struct sk_buff *nskb;
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struct iphdr *iph, *niph;
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struct tcphdr *nth;
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unsigned int tcp_hdr_size;
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iph = ip_hdr(skb);
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tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
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nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
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GFP_ATOMIC);
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if (nskb == NULL)
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return;
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skb_reserve(nskb, MAX_TCP_HEADER);
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niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
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skb_reset_transport_header(nskb);
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nth = skb_put(nskb, tcp_hdr_size);
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nth->source = th->source;
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nth->dest = th->dest;
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nth->seq = htonl(recv_seq - 1);
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/* ack_seq is used to relay our ISN to the synproxy hook to initialize
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* sequence number translation once a connection tracking entry exists.
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*/
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nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
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tcp_flag_word(nth) = TCP_FLAG_SYN;
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if (opts->options & XT_SYNPROXY_OPT_ECN)
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tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
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nth->doff = tcp_hdr_size / 4;
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nth->window = th->window;
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nth->check = 0;
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nth->urg_ptr = 0;
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synproxy_build_options(nth, opts);
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synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
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niph, nth, tcp_hdr_size);
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}
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static void
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synproxy_send_server_ack(struct net *net,
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const struct ip_ct_tcp *state,
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const struct sk_buff *skb, const struct tcphdr *th,
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const struct synproxy_options *opts)
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{
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struct sk_buff *nskb;
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struct iphdr *iph, *niph;
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struct tcphdr *nth;
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unsigned int tcp_hdr_size;
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iph = ip_hdr(skb);
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tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
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nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
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GFP_ATOMIC);
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if (nskb == NULL)
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return;
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skb_reserve(nskb, MAX_TCP_HEADER);
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niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
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skb_reset_transport_header(nskb);
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nth = skb_put(nskb, tcp_hdr_size);
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nth->source = th->dest;
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nth->dest = th->source;
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nth->seq = htonl(ntohl(th->ack_seq));
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nth->ack_seq = htonl(ntohl(th->seq) + 1);
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tcp_flag_word(nth) = TCP_FLAG_ACK;
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nth->doff = tcp_hdr_size / 4;
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nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
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nth->check = 0;
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nth->urg_ptr = 0;
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synproxy_build_options(nth, opts);
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synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
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}
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static void
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synproxy_send_client_ack(struct net *net,
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const struct sk_buff *skb, const struct tcphdr *th,
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const struct synproxy_options *opts)
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{
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struct sk_buff *nskb;
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struct iphdr *iph, *niph;
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struct tcphdr *nth;
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unsigned int tcp_hdr_size;
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iph = ip_hdr(skb);
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tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
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nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
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GFP_ATOMIC);
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if (nskb == NULL)
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return;
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skb_reserve(nskb, MAX_TCP_HEADER);
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niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
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skb_reset_transport_header(nskb);
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nth = skb_put(nskb, tcp_hdr_size);
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nth->source = th->source;
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nth->dest = th->dest;
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nth->seq = htonl(ntohl(th->seq) + 1);
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nth->ack_seq = th->ack_seq;
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tcp_flag_word(nth) = TCP_FLAG_ACK;
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nth->doff = tcp_hdr_size / 4;
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nth->window = htons(ntohs(th->window) >> opts->wscale);
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nth->check = 0;
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nth->urg_ptr = 0;
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synproxy_build_options(nth, opts);
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synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
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IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
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}
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static bool
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synproxy_recv_client_ack(struct net *net,
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const struct sk_buff *skb, const struct tcphdr *th,
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struct synproxy_options *opts, u32 recv_seq)
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{
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struct synproxy_net *snet = synproxy_pernet(net);
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int mss;
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mss = __cookie_v4_check(ip_hdr(skb), th, ntohl(th->ack_seq) - 1);
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if (mss == 0) {
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this_cpu_inc(snet->stats->cookie_invalid);
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return false;
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}
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this_cpu_inc(snet->stats->cookie_valid);
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opts->mss = mss;
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opts->options |= XT_SYNPROXY_OPT_MSS;
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if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
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synproxy_check_timestamp_cookie(opts);
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synproxy_send_server_syn(net, skb, th, opts, recv_seq);
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return true;
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}
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#include <net/netfilter/nf_synproxy.h>
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static unsigned int
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synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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@ -309,135 +62,6 @@ synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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return XT_CONTINUE;
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}
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static unsigned int ipv4_synproxy_hook(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *nhs)
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{
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struct net *net = nhs->net;
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struct synproxy_net *snet = synproxy_pernet(net);
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct;
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struct nf_conn_synproxy *synproxy;
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struct synproxy_options opts = {};
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const struct ip_ct_tcp *state;
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struct tcphdr *th, _th;
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unsigned int thoff;
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ct = nf_ct_get(skb, &ctinfo);
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if (ct == NULL)
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return NF_ACCEPT;
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synproxy = nfct_synproxy(ct);
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if (synproxy == NULL)
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return NF_ACCEPT;
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if (nf_is_loopback_packet(skb) ||
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ip_hdr(skb)->protocol != IPPROTO_TCP)
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return NF_ACCEPT;
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thoff = ip_hdrlen(skb);
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th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
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if (th == NULL)
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return NF_DROP;
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state = &ct->proto.tcp;
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switch (state->state) {
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case TCP_CONNTRACK_CLOSE:
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if (th->rst && !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
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nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
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ntohl(th->seq) + 1);
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break;
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}
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if (!th->syn || th->ack ||
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CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
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break;
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/* Reopened connection - reset the sequence number and timestamp
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* adjustments, they will get initialized once the connection is
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* reestablished.
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*/
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nf_ct_seqadj_init(ct, ctinfo, 0);
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synproxy->tsoff = 0;
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this_cpu_inc(snet->stats->conn_reopened);
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/* fall through */
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case TCP_CONNTRACK_SYN_SENT:
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if (!synproxy_parse_options(skb, thoff, th, &opts))
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return NF_DROP;
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if (!th->syn && th->ack &&
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CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
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/* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
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* therefore we need to add 1 to make the SYN sequence
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* number match the one of first SYN.
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*/
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if (synproxy_recv_client_ack(net, skb, th, &opts,
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ntohl(th->seq) + 1)) {
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this_cpu_inc(snet->stats->cookie_retrans);
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consume_skb(skb);
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return NF_STOLEN;
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} else {
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return NF_DROP;
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}
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}
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synproxy->isn = ntohl(th->ack_seq);
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if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
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synproxy->its = opts.tsecr;
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nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
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break;
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case TCP_CONNTRACK_SYN_RECV:
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if (!th->syn || !th->ack)
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break;
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if (!synproxy_parse_options(skb, thoff, th, &opts))
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return NF_DROP;
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if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP) {
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synproxy->tsoff = opts.tsval - synproxy->its;
|
||||
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
||||
}
|
||||
|
||||
opts.options &= ~(XT_SYNPROXY_OPT_MSS |
|
||||
XT_SYNPROXY_OPT_WSCALE |
|
||||
XT_SYNPROXY_OPT_SACK_PERM);
|
||||
|
||||
swap(opts.tsval, opts.tsecr);
|
||||
synproxy_send_server_ack(net, state, skb, th, &opts);
|
||||
|
||||
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
|
||||
nf_conntrack_event_cache(IPCT_SEQADJ, ct);
|
||||
|
||||
swap(opts.tsval, opts.tsecr);
|
||||
synproxy_send_client_ack(net, skb, th, &opts);
|
||||
|
||||
consume_skb(skb);
|
||||
return NF_STOLEN;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
|
||||
synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
|
||||
return NF_ACCEPT;
|
||||
}
|
||||
|
||||
static const struct nf_hook_ops ipv4_synproxy_ops[] = {
|
||||
{
|
||||
.hook = ipv4_synproxy_hook,
|
||||
.pf = NFPROTO_IPV4,
|
||||
.hooknum = NF_INET_LOCAL_IN,
|
||||
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
||||
},
|
||||
{
|
||||
.hook = ipv4_synproxy_hook,
|
||||
.pf = NFPROTO_IPV4,
|
||||
.hooknum = NF_INET_POST_ROUTING,
|
||||
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
||||
},
|
||||
};
|
||||
|
||||
static int synproxy_tg4_check(const struct xt_tgchk_param *par)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(par->net);
|
||||
@ -452,13 +76,10 @@ static int synproxy_tg4_check(const struct xt_tgchk_param *par)
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
if (snet->hook_ref4 == 0) {
|
||||
err = nf_register_net_hooks(par->net, ipv4_synproxy_ops,
|
||||
ARRAY_SIZE(ipv4_synproxy_ops));
|
||||
if (err) {
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
return err;
|
||||
}
|
||||
err = nf_synproxy_ipv4_init(snet, par->net);
|
||||
if (err) {
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
return err;
|
||||
}
|
||||
|
||||
snet->hook_ref4++;
|
||||
@ -469,10 +90,7 @@ static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(par->net);
|
||||
|
||||
snet->hook_ref4--;
|
||||
if (snet->hook_ref4 == 0)
|
||||
nf_unregister_net_hooks(par->net, ipv4_synproxy_ops,
|
||||
ARRAY_SIZE(ipv4_synproxy_ops));
|
||||
nf_synproxy_ipv4_fini(snet, par->net);
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
}
|
||||
|
||||
|
||||
@ -6,272 +6,11 @@
|
||||
* published by the Free Software Foundation.
|
||||
*/
|
||||
|
||||
#include <linux/module.h>
|
||||
#include <linux/skbuff.h>
|
||||
#include <net/ip6_checksum.h>
|
||||
#include <net/ip6_route.h>
|
||||
#include <net/tcp.h>
|
||||
|
||||
#include <linux/netfilter_ipv6/ip6_tables.h>
|
||||
#include <linux/netfilter/x_tables.h>
|
||||
#include <linux/netfilter/xt_SYNPROXY.h>
|
||||
#include <net/netfilter/nf_conntrack.h>
|
||||
#include <net/netfilter/nf_conntrack_seqadj.h>
|
||||
#include <net/netfilter/nf_conntrack_synproxy.h>
|
||||
#include <net/netfilter/nf_conntrack_ecache.h>
|
||||
|
||||
static struct ipv6hdr *
|
||||
synproxy_build_ip(struct net *net, struct sk_buff *skb,
|
||||
const struct in6_addr *saddr,
|
||||
const struct in6_addr *daddr)
|
||||
{
|
||||
struct ipv6hdr *iph;
|
||||
|
||||
skb_reset_network_header(skb);
|
||||
iph = skb_put(skb, sizeof(*iph));
|
||||
ip6_flow_hdr(iph, 0, 0);
|
||||
iph->hop_limit = net->ipv6.devconf_all->hop_limit;
|
||||
iph->nexthdr = IPPROTO_TCP;
|
||||
iph->saddr = *saddr;
|
||||
iph->daddr = *daddr;
|
||||
|
||||
return iph;
|
||||
}
|
||||
|
||||
static void
|
||||
synproxy_send_tcp(struct net *net,
|
||||
const struct sk_buff *skb, struct sk_buff *nskb,
|
||||
struct nf_conntrack *nfct, enum ip_conntrack_info ctinfo,
|
||||
struct ipv6hdr *niph, struct tcphdr *nth,
|
||||
unsigned int tcp_hdr_size)
|
||||
{
|
||||
struct dst_entry *dst;
|
||||
struct flowi6 fl6;
|
||||
|
||||
nth->check = ~tcp_v6_check(tcp_hdr_size, &niph->saddr, &niph->daddr, 0);
|
||||
nskb->ip_summed = CHECKSUM_PARTIAL;
|
||||
nskb->csum_start = (unsigned char *)nth - nskb->head;
|
||||
nskb->csum_offset = offsetof(struct tcphdr, check);
|
||||
|
||||
memset(&fl6, 0, sizeof(fl6));
|
||||
fl6.flowi6_proto = IPPROTO_TCP;
|
||||
fl6.saddr = niph->saddr;
|
||||
fl6.daddr = niph->daddr;
|
||||
fl6.fl6_sport = nth->source;
|
||||
fl6.fl6_dport = nth->dest;
|
||||
security_skb_classify_flow((struct sk_buff *)skb, flowi6_to_flowi(&fl6));
|
||||
dst = ip6_route_output(net, NULL, &fl6);
|
||||
if (dst->error) {
|
||||
dst_release(dst);
|
||||
goto free_nskb;
|
||||
}
|
||||
dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
|
||||
if (IS_ERR(dst))
|
||||
goto free_nskb;
|
||||
|
||||
skb_dst_set(nskb, dst);
|
||||
|
||||
if (nfct) {
|
||||
nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
|
||||
nf_conntrack_get(nfct);
|
||||
}
|
||||
|
||||
ip6_local_out(net, nskb->sk, nskb);
|
||||
return;
|
||||
|
||||
free_nskb:
|
||||
kfree_skb(nskb);
|
||||
}
|
||||
|
||||
static void
|
||||
synproxy_send_client_synack(struct net *net,
|
||||
const struct sk_buff *skb, const struct tcphdr *th,
|
||||
const struct synproxy_options *opts)
|
||||
{
|
||||
struct sk_buff *nskb;
|
||||
struct ipv6hdr *iph, *niph;
|
||||
struct tcphdr *nth;
|
||||
unsigned int tcp_hdr_size;
|
||||
u16 mss = opts->mss;
|
||||
|
||||
iph = ipv6_hdr(skb);
|
||||
|
||||
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
||||
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
||||
GFP_ATOMIC);
|
||||
if (nskb == NULL)
|
||||
return;
|
||||
skb_reserve(nskb, MAX_TCP_HEADER);
|
||||
|
||||
niph = synproxy_build_ip(net, nskb, &iph->daddr, &iph->saddr);
|
||||
|
||||
skb_reset_transport_header(nskb);
|
||||
nth = skb_put(nskb, tcp_hdr_size);
|
||||
nth->source = th->dest;
|
||||
nth->dest = th->source;
|
||||
nth->seq = htonl(__cookie_v6_init_sequence(iph, th, &mss));
|
||||
nth->ack_seq = htonl(ntohl(th->seq) + 1);
|
||||
tcp_flag_word(nth) = TCP_FLAG_SYN | TCP_FLAG_ACK;
|
||||
if (opts->options & XT_SYNPROXY_OPT_ECN)
|
||||
tcp_flag_word(nth) |= TCP_FLAG_ECE;
|
||||
nth->doff = tcp_hdr_size / 4;
|
||||
nth->window = 0;
|
||||
nth->check = 0;
|
||||
nth->urg_ptr = 0;
|
||||
|
||||
synproxy_build_options(nth, opts);
|
||||
|
||||
synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
|
||||
IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
|
||||
}
|
||||
|
||||
static void
|
||||
synproxy_send_server_syn(struct net *net,
|
||||
const struct sk_buff *skb, const struct tcphdr *th,
|
||||
const struct synproxy_options *opts, u32 recv_seq)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(net);
|
||||
struct sk_buff *nskb;
|
||||
struct ipv6hdr *iph, *niph;
|
||||
struct tcphdr *nth;
|
||||
unsigned int tcp_hdr_size;
|
||||
|
||||
iph = ipv6_hdr(skb);
|
||||
|
||||
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
||||
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
||||
GFP_ATOMIC);
|
||||
if (nskb == NULL)
|
||||
return;
|
||||
skb_reserve(nskb, MAX_TCP_HEADER);
|
||||
|
||||
niph = synproxy_build_ip(net, nskb, &iph->saddr, &iph->daddr);
|
||||
|
||||
skb_reset_transport_header(nskb);
|
||||
nth = skb_put(nskb, tcp_hdr_size);
|
||||
nth->source = th->source;
|
||||
nth->dest = th->dest;
|
||||
nth->seq = htonl(recv_seq - 1);
|
||||
/* ack_seq is used to relay our ISN to the synproxy hook to initialize
|
||||
* sequence number translation once a connection tracking entry exists.
|
||||
*/
|
||||
nth->ack_seq = htonl(ntohl(th->ack_seq) - 1);
|
||||
tcp_flag_word(nth) = TCP_FLAG_SYN;
|
||||
if (opts->options & XT_SYNPROXY_OPT_ECN)
|
||||
tcp_flag_word(nth) |= TCP_FLAG_ECE | TCP_FLAG_CWR;
|
||||
nth->doff = tcp_hdr_size / 4;
|
||||
nth->window = th->window;
|
||||
nth->check = 0;
|
||||
nth->urg_ptr = 0;
|
||||
|
||||
synproxy_build_options(nth, opts);
|
||||
|
||||
synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
|
||||
niph, nth, tcp_hdr_size);
|
||||
}
|
||||
|
||||
static void
|
||||
synproxy_send_server_ack(struct net *net,
|
||||
const struct ip_ct_tcp *state,
|
||||
const struct sk_buff *skb, const struct tcphdr *th,
|
||||
const struct synproxy_options *opts)
|
||||
{
|
||||
struct sk_buff *nskb;
|
||||
struct ipv6hdr *iph, *niph;
|
||||
struct tcphdr *nth;
|
||||
unsigned int tcp_hdr_size;
|
||||
|
||||
iph = ipv6_hdr(skb);
|
||||
|
||||
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
||||
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
||||
GFP_ATOMIC);
|
||||
if (nskb == NULL)
|
||||
return;
|
||||
skb_reserve(nskb, MAX_TCP_HEADER);
|
||||
|
||||
niph = synproxy_build_ip(net, nskb, &iph->daddr, &iph->saddr);
|
||||
|
||||
skb_reset_transport_header(nskb);
|
||||
nth = skb_put(nskb, tcp_hdr_size);
|
||||
nth->source = th->dest;
|
||||
nth->dest = th->source;
|
||||
nth->seq = htonl(ntohl(th->ack_seq));
|
||||
nth->ack_seq = htonl(ntohl(th->seq) + 1);
|
||||
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
||||
nth->doff = tcp_hdr_size / 4;
|
||||
nth->window = htons(state->seen[IP_CT_DIR_ORIGINAL].td_maxwin);
|
||||
nth->check = 0;
|
||||
nth->urg_ptr = 0;
|
||||
|
||||
synproxy_build_options(nth, opts);
|
||||
|
||||
synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
|
||||
}
|
||||
|
||||
static void
|
||||
synproxy_send_client_ack(struct net *net,
|
||||
const struct sk_buff *skb, const struct tcphdr *th,
|
||||
const struct synproxy_options *opts)
|
||||
{
|
||||
struct sk_buff *nskb;
|
||||
struct ipv6hdr *iph, *niph;
|
||||
struct tcphdr *nth;
|
||||
unsigned int tcp_hdr_size;
|
||||
|
||||
iph = ipv6_hdr(skb);
|
||||
|
||||
tcp_hdr_size = sizeof(*nth) + synproxy_options_size(opts);
|
||||
nskb = alloc_skb(sizeof(*niph) + tcp_hdr_size + MAX_TCP_HEADER,
|
||||
GFP_ATOMIC);
|
||||
if (nskb == NULL)
|
||||
return;
|
||||
skb_reserve(nskb, MAX_TCP_HEADER);
|
||||
|
||||
niph = synproxy_build_ip(net, nskb, &iph->saddr, &iph->daddr);
|
||||
|
||||
skb_reset_transport_header(nskb);
|
||||
nth = skb_put(nskb, tcp_hdr_size);
|
||||
nth->source = th->source;
|
||||
nth->dest = th->dest;
|
||||
nth->seq = htonl(ntohl(th->seq) + 1);
|
||||
nth->ack_seq = th->ack_seq;
|
||||
tcp_flag_word(nth) = TCP_FLAG_ACK;
|
||||
nth->doff = tcp_hdr_size / 4;
|
||||
nth->window = htons(ntohs(th->window) >> opts->wscale);
|
||||
nth->check = 0;
|
||||
nth->urg_ptr = 0;
|
||||
|
||||
synproxy_build_options(nth, opts);
|
||||
|
||||
synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
|
||||
IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
|
||||
}
|
||||
|
||||
static bool
|
||||
synproxy_recv_client_ack(struct net *net,
|
||||
const struct sk_buff *skb, const struct tcphdr *th,
|
||||
struct synproxy_options *opts, u32 recv_seq)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(net);
|
||||
int mss;
|
||||
|
||||
mss = __cookie_v6_check(ipv6_hdr(skb), th, ntohl(th->ack_seq) - 1);
|
||||
if (mss == 0) {
|
||||
this_cpu_inc(snet->stats->cookie_invalid);
|
||||
return false;
|
||||
}
|
||||
|
||||
this_cpu_inc(snet->stats->cookie_valid);
|
||||
opts->mss = mss;
|
||||
opts->options |= XT_SYNPROXY_OPT_MSS;
|
||||
|
||||
if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
|
||||
synproxy_check_timestamp_cookie(opts);
|
||||
|
||||
synproxy_send_server_syn(net, skb, th, opts, recv_seq);
|
||||
return true;
|
||||
}
|
||||
#include <net/netfilter/nf_synproxy.h>
|
||||
|
||||
static unsigned int
|
||||
synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par)
|
||||
@ -307,13 +46,14 @@ synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par)
|
||||
XT_SYNPROXY_OPT_SACK_PERM |
|
||||
XT_SYNPROXY_OPT_ECN);
|
||||
|
||||
synproxy_send_client_synack(net, skb, th, &opts);
|
||||
synproxy_send_client_synack_ipv6(net, skb, th, &opts);
|
||||
consume_skb(skb);
|
||||
return NF_STOLEN;
|
||||
|
||||
} else if (th->ack && !(th->fin || th->rst || th->syn)) {
|
||||
/* ACK from client */
|
||||
if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) {
|
||||
if (synproxy_recv_client_ack_ipv6(net, skb, th, &opts,
|
||||
ntohl(th->seq))) {
|
||||
consume_skb(skb);
|
||||
return NF_STOLEN;
|
||||
} else {
|
||||
@ -324,141 +64,6 @@ synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par)
|
||||
return XT_CONTINUE;
|
||||
}
|
||||
|
||||
static unsigned int ipv6_synproxy_hook(void *priv,
|
||||
struct sk_buff *skb,
|
||||
const struct nf_hook_state *nhs)
|
||||
{
|
||||
struct net *net = nhs->net;
|
||||
struct synproxy_net *snet = synproxy_pernet(net);
|
||||
enum ip_conntrack_info ctinfo;
|
||||
struct nf_conn *ct;
|
||||
struct nf_conn_synproxy *synproxy;
|
||||
struct synproxy_options opts = {};
|
||||
const struct ip_ct_tcp *state;
|
||||
struct tcphdr *th, _th;
|
||||
__be16 frag_off;
|
||||
u8 nexthdr;
|
||||
int thoff;
|
||||
|
||||
ct = nf_ct_get(skb, &ctinfo);
|
||||
if (ct == NULL)
|
||||
return NF_ACCEPT;
|
||||
|
||||
synproxy = nfct_synproxy(ct);
|
||||
if (synproxy == NULL)
|
||||
return NF_ACCEPT;
|
||||
|
||||
if (nf_is_loopback_packet(skb))
|
||||
return NF_ACCEPT;
|
||||
|
||||
nexthdr = ipv6_hdr(skb)->nexthdr;
|
||||
thoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr,
|
||||
&frag_off);
|
||||
if (thoff < 0 || nexthdr != IPPROTO_TCP)
|
||||
return NF_ACCEPT;
|
||||
|
||||
th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
|
||||
if (th == NULL)
|
||||
return NF_DROP;
|
||||
|
||||
state = &ct->proto.tcp;
|
||||
switch (state->state) {
|
||||
case TCP_CONNTRACK_CLOSE:
|
||||
if (th->rst && !test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
|
||||
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn -
|
||||
ntohl(th->seq) + 1);
|
||||
break;
|
||||
}
|
||||
|
||||
if (!th->syn || th->ack ||
|
||||
CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
|
||||
break;
|
||||
|
||||
/* Reopened connection - reset the sequence number and timestamp
|
||||
* adjustments, they will get initialized once the connection is
|
||||
* reestablished.
|
||||
*/
|
||||
nf_ct_seqadj_init(ct, ctinfo, 0);
|
||||
synproxy->tsoff = 0;
|
||||
this_cpu_inc(snet->stats->conn_reopened);
|
||||
|
||||
/* fall through */
|
||||
case TCP_CONNTRACK_SYN_SENT:
|
||||
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
||||
return NF_DROP;
|
||||
|
||||
if (!th->syn && th->ack &&
|
||||
CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
|
||||
/* Keep-Alives are sent with SEG.SEQ = SND.NXT-1,
|
||||
* therefore we need to add 1 to make the SYN sequence
|
||||
* number match the one of first SYN.
|
||||
*/
|
||||
if (synproxy_recv_client_ack(net, skb, th, &opts,
|
||||
ntohl(th->seq) + 1)) {
|
||||
this_cpu_inc(snet->stats->cookie_retrans);
|
||||
consume_skb(skb);
|
||||
return NF_STOLEN;
|
||||
} else {
|
||||
return NF_DROP;
|
||||
}
|
||||
}
|
||||
|
||||
synproxy->isn = ntohl(th->ack_seq);
|
||||
if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
|
||||
synproxy->its = opts.tsecr;
|
||||
|
||||
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
||||
break;
|
||||
case TCP_CONNTRACK_SYN_RECV:
|
||||
if (!th->syn || !th->ack)
|
||||
break;
|
||||
|
||||
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
||||
return NF_DROP;
|
||||
|
||||
if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP) {
|
||||
synproxy->tsoff = opts.tsval - synproxy->its;
|
||||
nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
|
||||
}
|
||||
|
||||
opts.options &= ~(XT_SYNPROXY_OPT_MSS |
|
||||
XT_SYNPROXY_OPT_WSCALE |
|
||||
XT_SYNPROXY_OPT_SACK_PERM);
|
||||
|
||||
swap(opts.tsval, opts.tsecr);
|
||||
synproxy_send_server_ack(net, state, skb, th, &opts);
|
||||
|
||||
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
|
||||
nf_conntrack_event_cache(IPCT_SEQADJ, ct);
|
||||
|
||||
swap(opts.tsval, opts.tsecr);
|
||||
synproxy_send_client_ack(net, skb, th, &opts);
|
||||
|
||||
consume_skb(skb);
|
||||
return NF_STOLEN;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
|
||||
synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
|
||||
return NF_ACCEPT;
|
||||
}
|
||||
|
||||
static const struct nf_hook_ops ipv6_synproxy_ops[] = {
|
||||
{
|
||||
.hook = ipv6_synproxy_hook,
|
||||
.pf = NFPROTO_IPV6,
|
||||
.hooknum = NF_INET_LOCAL_IN,
|
||||
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
||||
},
|
||||
{
|
||||
.hook = ipv6_synproxy_hook,
|
||||
.pf = NFPROTO_IPV6,
|
||||
.hooknum = NF_INET_POST_ROUTING,
|
||||
.priority = NF_IP_PRI_CONNTRACK_CONFIRM - 1,
|
||||
},
|
||||
};
|
||||
|
||||
static int synproxy_tg6_check(const struct xt_tgchk_param *par)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(par->net);
|
||||
@ -474,16 +79,12 @@ static int synproxy_tg6_check(const struct xt_tgchk_param *par)
|
||||
if (err)
|
||||
return err;
|
||||
|
||||
if (snet->hook_ref6 == 0) {
|
||||
err = nf_register_net_hooks(par->net, ipv6_synproxy_ops,
|
||||
ARRAY_SIZE(ipv6_synproxy_ops));
|
||||
if (err) {
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
return err;
|
||||
}
|
||||
err = nf_synproxy_ipv6_init(snet, par->net);
|
||||
if (err) {
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
return err;
|
||||
}
|
||||
|
||||
snet->hook_ref6++;
|
||||
return err;
|
||||
}
|
||||
|
||||
@ -491,10 +92,7 @@ static void synproxy_tg6_destroy(const struct xt_tgdtor_param *par)
|
||||
{
|
||||
struct synproxy_net *snet = synproxy_pernet(par->net);
|
||||
|
||||
snet->hook_ref6--;
|
||||
if (snet->hook_ref6 == 0)
|
||||
nf_unregister_net_hooks(par->net, ipv6_synproxy_ops,
|
||||
ARRAY_SIZE(ipv6_synproxy_ops));
|
||||
nf_synproxy_ipv6_fini(snet, par->net);
|
||||
nf_ct_netns_put(par->net, par->family);
|
||||
}
|
||||
|
||||
|
||||
File diff suppressed because it is too large
Load Diff
Loading…
Reference in New Issue
Block a user