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Message-Id: <20190625001233.22057-17-pablo@netfilter.org>
Date: Tue, 25 Jun 2019 02:12:23 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 16/26] netfilter: synproxy: extract SYNPROXY infrastructure from {ipt, ip6t}_SYNPROXY
From: Fernando Fernandez Mancera <ffmancera@...eup.net>
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@...eup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/net/netfilter/nf_conntrack_synproxy.h | 13 +-
include/net/netfilter/nf_synproxy.h | 44 ++
net/ipv4/netfilter/ipt_SYNPROXY.c | 394 +----------
net/ipv6/netfilter/ip6t_SYNPROXY.c | 420 +-----------
net/netfilter/nf_synproxy_core.c | 896 ++++++++++++++++++++++++--
5 files changed, 920 insertions(+), 847 deletions(-)
create mode 100644 include/net/netfilter/nf_synproxy.h
diff --git a/include/net/netfilter/nf_conntrack_synproxy.h b/include/net/netfilter/nf_conntrack_synproxy.h
index 2c7559a54092..c5659dcf5b1a 100644
--- a/include/net/netfilter/nf_conntrack_synproxy.h
+++ b/include/net/netfilter/nf_conntrack_synproxy.h
@@ -72,21 +72,12 @@ struct synproxy_options {
};
struct tcphdr;
-struct xt_synproxy_info;
+struct nf_synproxy_info;
bool synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
const struct tcphdr *th,
struct synproxy_options *opts);
-unsigned int synproxy_options_size(const struct synproxy_options *opts);
-void synproxy_build_options(struct tcphdr *th,
- const struct synproxy_options *opts);
-void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
+void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
struct synproxy_options *opts);
-void synproxy_check_timestamp_cookie(struct synproxy_options *opts);
-
-unsigned int synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
- struct tcphdr *th, struct nf_conn *ct,
- enum ip_conntrack_info ctinfo,
- const struct nf_conn_synproxy *synproxy);
#endif /* _NF_CONNTRACK_SYNPROXY_H */
diff --git a/include/net/netfilter/nf_synproxy.h b/include/net/netfilter/nf_synproxy.h
new file mode 100644
index 000000000000..3e8b3f03b687
--- /dev/null
+++ b/include/net/netfilter/nf_synproxy.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NF_SYNPROXY_SHARED_H
+#define _NF_SYNPROXY_SHARED_H
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <net/ip6_checksum.h>
+#include <net/ip6_route.h>
+#include <net/tcp.h>
+
+#include <net/netfilter/nf_conntrack_seqadj.h>
+#include <net/netfilter/nf_conntrack_synproxy.h>
+
+void synproxy_send_client_synack(struct net *net, const struct sk_buff *skb,
+ const struct tcphdr *th,
+ const struct synproxy_options *opts);
+
+bool synproxy_recv_client_ack(struct net *net,
+ const struct sk_buff *skb,
+ const struct tcphdr *th,
+ struct synproxy_options *opts, u32 recv_seq);
+
+unsigned int ipv4_synproxy_hook(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *nhs);
+int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net);
+void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net);
+
+#if IS_ENABLED(CONFIG_IPV6)
+void synproxy_send_client_synack_ipv6(struct net *net,
+ const struct sk_buff *skb,
+ const struct tcphdr *th,
+ const struct synproxy_options *opts);
+
+bool synproxy_recv_client_ack_ipv6(struct net *net, const struct sk_buff *skb,
+ const struct tcphdr *th,
+ struct synproxy_options *opts, u32 recv_seq);
+
+unsigned int ipv6_synproxy_hook(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *nhs);
+int nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net);
+void nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net);
+#endif /* CONFIG_IPV6 */
+
+#endif /* _NF_SYNPROXY_SHARED_H */
diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c
index 690b17ef6a44..7f7979734fb4 100644
--- a/net/ipv4/netfilter/ipt_SYNPROXY.c
+++ b/net/ipv4/netfilter/ipt_SYNPROXY.c
@@ -6,258 +6,11 @@
* published by the Free Software Foundation.
*/
-#include <linux/module.h>
-#include <linux/skbuff.h>
-#include <net/tcp.h>
-
#include <linux/netfilter_ipv4/ip_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 iphdr *
-synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
- __be32 daddr)
-{
- struct iphdr *iph;
-
- skb_reset_network_header(skb);
- iph = skb_put(skb, sizeof(*iph));
- iph->version = 4;
- iph->ihl = sizeof(*iph) / 4;
- iph->tos = 0;
- iph->id = 0;
- iph->frag_off = htons(IP_DF);
- iph->ttl = net->ipv4.sysctl_ip_default_ttl;
- iph->protocol = IPPROTO_TCP;
- iph->check = 0;
- 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 iphdr *niph, struct tcphdr *nth,
- unsigned int tcp_hdr_size)
-{
- nth->check = ~tcp_v4_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);
-
- skb_dst_set_noref(nskb, skb_dst(skb));
- nskb->protocol = htons(ETH_P_IP);
- if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
- goto free_nskb;
-
- if (nfct) {
- nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
- nf_conntrack_get(nfct);
- }
-
- ip_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 iphdr *iph, *niph;
- struct tcphdr *nth;
- unsigned int tcp_hdr_size;
- u16 mss = opts->mss;
-
- iph = ip_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_v4_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 iphdr *iph, *niph;
- struct tcphdr *nth;
- unsigned int tcp_hdr_size;
-
- iph = ip_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 iphdr *iph, *niph;
- struct tcphdr *nth;
- unsigned int tcp_hdr_size;
-
- iph = ip_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 iphdr *iph, *niph;
- struct tcphdr *nth;
- unsigned int tcp_hdr_size;
-
- iph = ip_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_v4_check(ip_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_tg4(struct sk_buff *skb, const struct xt_action_param *par)
@@ -309,135 +62,6 @@ synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
return XT_CONTINUE;
}
-static unsigned int ipv4_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;
- unsigned 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) ||
- ip_hdr(skb)->protocol != IPPROTO_TCP)
- return NF_ACCEPT;
-
- thoff = ip_hdrlen(skb);
- 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 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);
}
diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c
index cb6d42b03cb5..55a9b92d0a1f 100644
--- a/net/ipv6/netfilter/ip6t_SYNPROXY.c
+++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c
@@ -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);
}
diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c
index 3d58a9e93e5a..50677285f82e 100644
--- a/net/netfilter/nf_synproxy_core.c
+++ b/net/netfilter/nf_synproxy_core.c
@@ -13,16 +13,16 @@
#include <net/netns/generic.h>
#include <linux/proc_fs.h>
-#include <linux/netfilter_ipv4/ip_tables.h>
-#include <linux/netfilter/x_tables.h>
-#include <linux/netfilter/xt_tcpudp.h>
-#include <linux/netfilter/xt_SYNPROXY.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/nf_SYNPROXY.h>
#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_seqadj.h>
#include <net/netfilter/nf_conntrack_synproxy.h>
#include <net/netfilter/nf_conntrack_zones.h>
+#include <net/netfilter/nf_synproxy.h>
unsigned int synproxy_net_id;
EXPORT_SYMBOL_GPL(synproxy_net_id);
@@ -60,7 +60,7 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
case TCPOPT_MSS:
if (opsize == TCPOLEN_MSS) {
opts->mss = get_unaligned_be16(ptr);
- opts->options |= XT_SYNPROXY_OPT_MSS;
+ opts->options |= NF_SYNPROXY_OPT_MSS;
}
break;
case TCPOPT_WINDOW:
@@ -68,19 +68,19 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
opts->wscale = *ptr;
if (opts->wscale > TCP_MAX_WSCALE)
opts->wscale = TCP_MAX_WSCALE;
- opts->options |= XT_SYNPROXY_OPT_WSCALE;
+ opts->options |= NF_SYNPROXY_OPT_WSCALE;
}
break;
case TCPOPT_TIMESTAMP:
if (opsize == TCPOLEN_TIMESTAMP) {
opts->tsval = get_unaligned_be32(ptr);
opts->tsecr = get_unaligned_be32(ptr + 4);
- opts->options |= XT_SYNPROXY_OPT_TIMESTAMP;
+ opts->options |= NF_SYNPROXY_OPT_TIMESTAMP;
}
break;
case TCPOPT_SACK_PERM:
if (opsize == TCPOLEN_SACK_PERM)
- opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
+ opts->options |= NF_SYNPROXY_OPT_SACK_PERM;
break;
}
@@ -92,36 +92,36 @@ synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
}
EXPORT_SYMBOL_GPL(synproxy_parse_options);
-unsigned int synproxy_options_size(const struct synproxy_options *opts)
+static unsigned int
+synproxy_options_size(const struct synproxy_options *opts)
{
unsigned int size = 0;
- if (opts->options & XT_SYNPROXY_OPT_MSS)
+ if (opts->options & NF_SYNPROXY_OPT_MSS)
size += TCPOLEN_MSS_ALIGNED;
- if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
+ if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
size += TCPOLEN_TSTAMP_ALIGNED;
- else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
+ else if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
size += TCPOLEN_SACKPERM_ALIGNED;
- if (opts->options & XT_SYNPROXY_OPT_WSCALE)
+ if (opts->options & NF_SYNPROXY_OPT_WSCALE)
size += TCPOLEN_WSCALE_ALIGNED;
return size;
}
-EXPORT_SYMBOL_GPL(synproxy_options_size);
-void
+static void
synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
{
__be32 *ptr = (__be32 *)(th + 1);
u8 options = opts->options;
- if (options & XT_SYNPROXY_OPT_MSS)
+ if (options & NF_SYNPROXY_OPT_MSS)
*ptr++ = htonl((TCPOPT_MSS << 24) |
(TCPOLEN_MSS << 16) |
opts->mss);
- if (options & XT_SYNPROXY_OPT_TIMESTAMP) {
- if (options & XT_SYNPROXY_OPT_SACK_PERM)
+ if (options & NF_SYNPROXY_OPT_TIMESTAMP) {
+ if (options & NF_SYNPROXY_OPT_SACK_PERM)
*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
(TCPOLEN_SACK_PERM << 16) |
(TCPOPT_TIMESTAMP << 8) |
@@ -134,58 +134,56 @@ synproxy_build_options(struct tcphdr *th, const struct synproxy_options *opts)
*ptr++ = htonl(opts->tsval);
*ptr++ = htonl(opts->tsecr);
- } else if (options & XT_SYNPROXY_OPT_SACK_PERM)
+ } else if (options & NF_SYNPROXY_OPT_SACK_PERM)
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_NOP << 16) |
(TCPOPT_SACK_PERM << 8) |
TCPOLEN_SACK_PERM);
- if (options & XT_SYNPROXY_OPT_WSCALE)
+ if (options & NF_SYNPROXY_OPT_WSCALE)
*ptr++ = htonl((TCPOPT_NOP << 24) |
(TCPOPT_WINDOW << 16) |
(TCPOLEN_WINDOW << 8) |
opts->wscale);
}
-EXPORT_SYMBOL_GPL(synproxy_build_options);
-void synproxy_init_timestamp_cookie(const struct xt_synproxy_info *info,
+void synproxy_init_timestamp_cookie(const struct nf_synproxy_info *info,
struct synproxy_options *opts)
{
opts->tsecr = opts->tsval;
opts->tsval = tcp_time_stamp_raw() & ~0x3f;
- if (opts->options & XT_SYNPROXY_OPT_WSCALE) {
+ if (opts->options & NF_SYNPROXY_OPT_WSCALE) {
opts->tsval |= opts->wscale;
opts->wscale = info->wscale;
} else
opts->tsval |= 0xf;
- if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
+ if (opts->options & NF_SYNPROXY_OPT_SACK_PERM)
opts->tsval |= 1 << 4;
- if (opts->options & XT_SYNPROXY_OPT_ECN)
+ if (opts->options & NF_SYNPROXY_OPT_ECN)
opts->tsval |= 1 << 5;
}
EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
-void synproxy_check_timestamp_cookie(struct synproxy_options *opts)
+static void
+synproxy_check_timestamp_cookie(struct synproxy_options *opts)
{
opts->wscale = opts->tsecr & 0xf;
if (opts->wscale != 0xf)
- opts->options |= XT_SYNPROXY_OPT_WSCALE;
+ opts->options |= NF_SYNPROXY_OPT_WSCALE;
- opts->options |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
+ opts->options |= opts->tsecr & (1 << 4) ? NF_SYNPROXY_OPT_SACK_PERM : 0;
- opts->options |= opts->tsecr & (1 << 5) ? XT_SYNPROXY_OPT_ECN : 0;
+ opts->options |= opts->tsecr & (1 << 5) ? NF_SYNPROXY_OPT_ECN : 0;
}
-EXPORT_SYMBOL_GPL(synproxy_check_timestamp_cookie);
-unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
- unsigned int protoff,
- struct tcphdr *th,
- struct nf_conn *ct,
- enum ip_conntrack_info ctinfo,
- const struct nf_conn_synproxy *synproxy)
+static unsigned int
+synproxy_tstamp_adjust(struct sk_buff *skb, unsigned int protoff,
+ struct tcphdr *th, struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ const struct nf_conn_synproxy *synproxy)
{
unsigned int optoff, optend;
__be32 *ptr, old;
@@ -235,7 +233,6 @@ unsigned int synproxy_tstamp_adjust(struct sk_buff *skb,
}
return 1;
}
-EXPORT_SYMBOL_GPL(synproxy_tstamp_adjust);
static struct nf_ct_ext_type nf_ct_synproxy_extend __read_mostly = {
.len = sizeof(struct nf_conn_synproxy),
@@ -416,5 +413,830 @@ static void __exit synproxy_core_exit(void)
module_init(synproxy_core_init);
module_exit(synproxy_core_exit);
+static struct iphdr *
+synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
+ __be32 daddr)
+{
+ struct iphdr *iph;
+
+ skb_reset_network_header(skb);
+ iph = skb_put(skb, sizeof(*iph));
+ iph->version = 4;
+ iph->ihl = sizeof(*iph) / 4;
+ iph->tos = 0;
+ iph->id = 0;
+ iph->frag_off = htons(IP_DF);
+ iph->ttl = net->ipv4.sysctl_ip_default_ttl;
+ iph->protocol = IPPROTO_TCP;
+ iph->check = 0;
+ 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 iphdr *niph, struct tcphdr *nth,
+ unsigned int tcp_hdr_size)
+{
+ nth->check = ~tcp_v4_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);
+
+ skb_dst_set_noref(nskb, skb_dst(skb));
+ nskb->protocol = htons(ETH_P_IP);
+ if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
+ goto free_nskb;
+
+ if (nfct) {
+ nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
+ nf_conntrack_get(nfct);
+ }
+
+ ip_local_out(net, nskb->sk, nskb);
+ return;
+
+free_nskb:
+ kfree_skb(nskb);
+}
+
+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 iphdr *iph, *niph;
+ struct tcphdr *nth;
+ unsigned int tcp_hdr_size;
+ u16 mss = opts->mss;
+
+ iph = ip_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)
+ 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_v4_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 & NF_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);
+}
+EXPORT_SYMBOL_GPL(synproxy_send_client_synack);
+
+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 iphdr *iph, *niph;
+ struct tcphdr *nth;
+ unsigned int tcp_hdr_size;
+
+ iph = ip_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)
+ 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 & NF_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 iphdr *iph, *niph;
+ struct tcphdr *nth;
+ unsigned int tcp_hdr_size;
+
+ iph = ip_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)
+ 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 iphdr *iph, *niph;
+ struct tcphdr *nth;
+ unsigned int tcp_hdr_size;
+
+ iph = ip_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)
+ 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);
+}
+
+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_v4_check(ip_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 |= NF_SYNPROXY_OPT_MSS;
+
+ if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
+ synproxy_check_timestamp_cookie(opts);
+
+ synproxy_send_server_syn(net, skb, th, opts, recv_seq);
+ return true;
+}
+EXPORT_SYMBOL_GPL(synproxy_recv_client_ack);
+
+unsigned int
+ipv4_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;
+ unsigned int thoff;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (!ct)
+ return NF_ACCEPT;
+
+ synproxy = nfct_synproxy(ct);
+ if (!synproxy)
+ return NF_ACCEPT;
+
+ if (nf_is_loopback_packet(skb) ||
+ ip_hdr(skb)->protocol != IPPROTO_TCP)
+ return NF_ACCEPT;
+
+ thoff = ip_hdrlen(skb);
+ th = skb_header_pointer(skb, thoff, sizeof(_th), &_th);
+ if (!th)
+ 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 & NF_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 & NF_SYNPROXY_OPT_TIMESTAMP) {
+ synproxy->tsoff = opts.tsval - synproxy->its;
+ nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
+ }
+
+ opts.options &= ~(NF_SYNPROXY_OPT_MSS |
+ NF_SYNPROXY_OPT_WSCALE |
+ NF_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;
+}
+EXPORT_SYMBOL_GPL(ipv4_synproxy_hook);
+
+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,
+ },
+};
+
+int nf_synproxy_ipv4_init(struct synproxy_net *snet, struct net *net)
+{
+ int err;
+
+ if (snet->hook_ref4 == 0) {
+ err = nf_register_net_hooks(net, ipv4_synproxy_ops,
+ ARRAY_SIZE(ipv4_synproxy_ops));
+ if (err)
+ return err;
+ }
+
+ snet->hook_ref4++;
+ return err;
+}
+EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_init);
+
+void nf_synproxy_ipv4_fini(struct synproxy_net *snet, struct net *net)
+{
+ snet->hook_ref4--;
+ if (snet->hook_ref4 == 0)
+ nf_unregister_net_hooks(net, ipv4_synproxy_ops,
+ ARRAY_SIZE(ipv4_synproxy_ops));
+}
+EXPORT_SYMBOL_GPL(nf_synproxy_ipv4_fini);
+
+#if IS_ENABLED(CONFIG_IPV6)
+static struct ipv6hdr *
+synproxy_build_ip_ipv6(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_ipv6(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;
+ int err;
+
+ 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));
+ err = nf_ip6_route(net, &dst, flowi6_to_flowi(&fl6), false);
+ if (err) {
+ 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);
+}
+
+void
+synproxy_send_client_synack_ipv6(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)
+ return;
+ skb_reserve(nskb, MAX_TCP_HEADER);
+
+ niph = synproxy_build_ip_ipv6(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(nf_ipv6_cookie_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 & NF_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_ipv6(net, skb, nskb, skb_nfct(skb),
+ IP_CT_ESTABLISHED_REPLY, niph, nth,
+ tcp_hdr_size);
+}
+EXPORT_SYMBOL_GPL(synproxy_send_client_synack_ipv6);
+
+static void
+synproxy_send_server_syn_ipv6(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)
+ return;
+ skb_reserve(nskb, MAX_TCP_HEADER);
+
+ niph = synproxy_build_ip_ipv6(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 & NF_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_ipv6(net, skb, nskb, &snet->tmpl->ct_general,
+ IP_CT_NEW, niph, nth, tcp_hdr_size);
+}
+
+static void
+synproxy_send_server_ack_ipv6(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)
+ return;
+ skb_reserve(nskb, MAX_TCP_HEADER);
+
+ niph = synproxy_build_ip_ipv6(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_ipv6(net, skb, nskb, NULL, 0, niph, nth,
+ tcp_hdr_size);
+}
+
+static void
+synproxy_send_client_ack_ipv6(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)
+ return;
+ skb_reserve(nskb, MAX_TCP_HEADER);
+
+ niph = synproxy_build_ip_ipv6(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_ipv6(net, skb, nskb, skb_nfct(skb),
+ IP_CT_ESTABLISHED_REPLY, niph, nth,
+ tcp_hdr_size);
+}
+
+bool
+synproxy_recv_client_ack_ipv6(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 |= NF_SYNPROXY_OPT_MSS;
+
+ if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
+ synproxy_check_timestamp_cookie(opts);
+
+ synproxy_send_server_syn_ipv6(net, skb, th, opts, recv_seq);
+ return true;
+}
+EXPORT_SYMBOL_GPL(synproxy_recv_client_ack_ipv6);
+
+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)
+ return NF_ACCEPT;
+
+ synproxy = nfct_synproxy(ct);
+ if (!synproxy)
+ 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)
+ 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_ipv6(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 & NF_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 & NF_SYNPROXY_OPT_TIMESTAMP) {
+ synproxy->tsoff = opts.tsval - synproxy->its;
+ nf_conntrack_event_cache(IPCT_SYNPROXY, ct);
+ }
+
+ opts.options &= ~(NF_SYNPROXY_OPT_MSS |
+ NF_SYNPROXY_OPT_WSCALE |
+ NF_SYNPROXY_OPT_SACK_PERM);
+
+ swap(opts.tsval, opts.tsecr);
+ synproxy_send_server_ack_ipv6(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_ipv6(net, skb, th, &opts);
+
+ consume_skb(skb);
+ return NF_STOLEN;
+ default:
+ break;
+ }
+
+ synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
+ return NF_ACCEPT;
+}
+EXPORT_SYMBOL_GPL(ipv6_synproxy_hook);
+
+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,
+ },
+};
+
+int
+nf_synproxy_ipv6_init(struct synproxy_net *snet, struct net *net)
+{
+ int err;
+
+ if (snet->hook_ref6 == 0) {
+ err = nf_register_net_hooks(net, ipv6_synproxy_ops,
+ ARRAY_SIZE(ipv6_synproxy_ops));
+ if (err)
+ return err;
+ }
+
+ snet->hook_ref6++;
+ return err;
+}
+EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_init);
+
+void
+nf_synproxy_ipv6_fini(struct synproxy_net *snet, struct net *net)
+{
+ snet->hook_ref6--;
+ if (snet->hook_ref6 == 0)
+ nf_unregister_net_hooks(net, ipv6_synproxy_ops,
+ ARRAY_SIZE(ipv6_synproxy_ops));
+}
+EXPORT_SYMBOL_GPL(nf_synproxy_ipv6_fini);
+#endif /* CONFIG_IPV6 */
+
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@...sh.net>");
--
2.11.0
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