2013-08-27 06:50:14 +00:00
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/*
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* Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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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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static struct iphdr *
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2016-03-26 08:32:57 +00:00
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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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2013-08-27 06:50:14 +00:00
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{
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struct iphdr *iph;
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skb_reset_network_header(skb);
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networking: make skb_put & friends return void pointers
It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.
Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:
@@
expression SKB, LEN;
typedef u8;
identifier fn = { skb_put, __skb_put };
@@
- *(fn(SKB, LEN))
+ *(u8 *)fn(SKB, LEN)
@@
expression E, SKB, LEN;
identifier fn = { skb_put, __skb_put };
type T;
@@
- E = ((T *)(fn(SKB, LEN)))
+ E = fn(SKB, LEN)
which actually doesn't cover pskb_put since there are only three
users overall.
A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-16 12:29:21 +00:00
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iph = skb_put(skb, sizeof(*iph));
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2013-08-27 06:50:14 +00:00
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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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2016-02-15 10:11:27 +00:00
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iph->ttl = net->ipv4.sysctl_ip_default_ttl;
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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synproxy_send_tcp(struct net *net,
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2015-09-25 20:07:29 +00:00
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const struct sk_buff *skb, struct sk_buff *nskb,
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2013-08-27 06:50:14 +00:00
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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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2015-09-25 20:07:30 +00:00
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if (ip_route_me_harder(net, nskb, RTN_UNSPEC))
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2013-08-27 06:50:14 +00:00
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goto free_nskb;
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if (nfct) {
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2017-01-23 17:21:57 +00:00
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nf_ct_set(nskb, (struct nf_conn *)nfct, ctinfo);
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2013-08-27 06:50:14 +00:00
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nf_conntrack_get(nfct);
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}
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2015-10-07 21:48:46 +00:00
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ip_local_out(net, nskb->sk, nskb);
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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synproxy_send_client_synack(struct net *net,
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2015-09-25 20:07:29 +00:00
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const struct sk_buff *skb, const struct tcphdr *th,
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
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2013-08-27 06:50:14 +00:00
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skb_reset_transport_header(nskb);
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networking: make skb_put & friends return void pointers
It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.
Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:
@@
expression SKB, LEN;
typedef u8;
identifier fn = { skb_put, __skb_put };
@@
- *(fn(SKB, LEN))
+ *(u8 *)fn(SKB, LEN)
@@
expression E, SKB, LEN;
identifier fn = { skb_put, __skb_put };
type T;
@@
- E = ((T *)(fn(SKB, LEN)))
+ E = fn(SKB, LEN)
which actually doesn't cover pskb_put since there are only three
users overall.
A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-16 12:29:21 +00:00
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nth = skb_put(nskb, tcp_hdr_size);
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2013-08-27 06:50:14 +00:00
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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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2017-01-23 17:21:56 +00:00
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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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2013-08-27 06:50:14 +00:00
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}
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static void
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2016-03-26 08:32:57 +00:00
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synproxy_send_server_syn(struct net *net,
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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struct synproxy_net *snet = synproxy_pernet(net);
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
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2013-08-27 06:50:14 +00:00
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skb_reset_transport_header(nskb);
|
networking: make skb_put & friends return void pointers
It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.
Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:
@@
expression SKB, LEN;
typedef u8;
identifier fn = { skb_put, __skb_put };
@@
- *(fn(SKB, LEN))
+ *(u8 *)fn(SKB, LEN)
@@
expression E, SKB, LEN;
identifier fn = { skb_put, __skb_put };
type T;
@@
- E = ((T *)(fn(SKB, LEN)))
+ E = fn(SKB, LEN)
which actually doesn't cover pskb_put since there are only three
users overall.
A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-16 12:29:21 +00:00
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nth = skb_put(nskb, tcp_hdr_size);
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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synproxy_send_tcp(net, skb, nskb, &snet->tmpl->ct_general, IP_CT_NEW,
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2013-08-27 06:50:14 +00:00
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niph, nth, tcp_hdr_size);
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}
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static void
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2016-03-26 08:32:57 +00:00
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synproxy_send_server_ack(struct net *net,
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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niph = synproxy_build_ip(net, nskb, iph->daddr, iph->saddr);
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2013-08-27 06:50:14 +00:00
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skb_reset_transport_header(nskb);
|
networking: make skb_put & friends return void pointers
It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.
Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:
@@
expression SKB, LEN;
typedef u8;
identifier fn = { skb_put, __skb_put };
@@
- *(fn(SKB, LEN))
+ *(u8 *)fn(SKB, LEN)
@@
expression E, SKB, LEN;
identifier fn = { skb_put, __skb_put };
type T;
@@
- E = ((T *)(fn(SKB, LEN)))
+ E = fn(SKB, LEN)
which actually doesn't cover pskb_put since there are only three
users overall.
A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-16 12:29:21 +00:00
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nth = skb_put(nskb, tcp_hdr_size);
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2013-08-27 06:50:14 +00:00
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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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2016-03-26 08:32:57 +00:00
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synproxy_send_tcp(net, skb, nskb, NULL, 0, niph, nth, tcp_hdr_size);
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2013-08-27 06:50:14 +00:00
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}
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static void
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2016-03-26 08:32:57 +00:00
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synproxy_send_client_ack(struct net *net,
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2013-08-27 06:50:14 +00:00
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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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|
2016-03-26 08:32:57 +00:00
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niph = synproxy_build_ip(net, nskb, iph->saddr, iph->daddr);
|
2013-08-27 06:50:14 +00:00
|
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skb_reset_transport_header(nskb);
|
networking: make skb_put & friends return void pointers
It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.
Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:
@@
expression SKB, LEN;
typedef u8;
identifier fn = { skb_put, __skb_put };
@@
- *(fn(SKB, LEN))
+ *(u8 *)fn(SKB, LEN)
@@
expression E, SKB, LEN;
identifier fn = { skb_put, __skb_put };
type T;
@@
- E = ((T *)(fn(SKB, LEN)))
+ E = fn(SKB, LEN)
which actually doesn't cover pskb_put since there are only three
users overall.
A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-06-16 12:29:21 +00:00
|
|
|
nth = skb_put(nskb, tcp_hdr_size);
|
2013-08-27 06:50:14 +00:00
|
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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;
|
2015-05-15 16:07:31 +00:00
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|
nth->window = htons(ntohs(th->window) >> opts->wscale);
|
2013-08-27 06:50:14 +00:00
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|
|
nth->check = 0;
|
|
|
|
nth->urg_ptr = 0;
|
|
|
|
|
|
|
|
synproxy_build_options(nth, opts);
|
|
|
|
|
2017-01-23 17:21:56 +00:00
|
|
|
synproxy_send_tcp(net, skb, nskb, skb_nfct(skb),
|
|
|
|
IP_CT_ESTABLISHED_REPLY, niph, nth, tcp_hdr_size);
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
static bool
|
2016-03-26 08:32:57 +00:00
|
|
|
synproxy_recv_client_ack(struct net *net,
|
2013-08-27 06:50:14 +00:00
|
|
|
const struct sk_buff *skb, const struct tcphdr *th,
|
|
|
|
struct synproxy_options *opts, u32 recv_seq)
|
|
|
|
{
|
2016-03-26 08:32:57 +00:00
|
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
2013-08-27 06:50:14 +00:00
|
|
|
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;
|
2013-11-14 14:35:30 +00:00
|
|
|
opts->options |= XT_SYNPROXY_OPT_MSS;
|
2013-08-27 06:50:14 +00:00
|
|
|
|
|
|
|
if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
|
|
|
|
synproxy_check_timestamp_cookie(opts);
|
|
|
|
|
2016-03-26 08:32:57 +00:00
|
|
|
synproxy_send_server_syn(net, skb, th, opts, recv_seq);
|
2013-08-27 06:50:14 +00:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
static unsigned int
|
|
|
|
synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
|
|
|
|
{
|
|
|
|
const struct xt_synproxy_info *info = par->targinfo;
|
2016-11-03 09:56:21 +00:00
|
|
|
struct net *net = xt_net(par);
|
2016-03-26 08:32:57 +00:00
|
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
2013-08-27 06:50:14 +00:00
|
|
|
struct synproxy_options opts = {};
|
|
|
|
struct tcphdr *th, _th;
|
|
|
|
|
2016-11-03 09:56:21 +00:00
|
|
|
if (nf_ip_checksum(skb, xt_hooknum(par), par->thoff, IPPROTO_TCP))
|
2013-08-27 06:50:14 +00:00
|
|
|
return NF_DROP;
|
|
|
|
|
|
|
|
th = skb_header_pointer(skb, par->thoff, sizeof(_th), &_th);
|
|
|
|
if (th == NULL)
|
|
|
|
return NF_DROP;
|
|
|
|
|
2013-09-30 07:51:46 +00:00
|
|
|
if (!synproxy_parse_options(skb, par->thoff, th, &opts))
|
|
|
|
return NF_DROP;
|
2013-08-27 06:50:14 +00:00
|
|
|
|
2013-08-28 13:14:38 +00:00
|
|
|
if (th->syn && !(th->ack || th->fin || th->rst)) {
|
2013-08-27 06:50:14 +00:00
|
|
|
/* Initial SYN from client */
|
|
|
|
this_cpu_inc(snet->stats->syn_received);
|
|
|
|
|
|
|
|
if (th->ece && th->cwr)
|
|
|
|
opts.options |= XT_SYNPROXY_OPT_ECN;
|
|
|
|
|
|
|
|
opts.options &= info->options;
|
|
|
|
if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
|
|
|
|
synproxy_init_timestamp_cookie(info, &opts);
|
|
|
|
else
|
|
|
|
opts.options &= ~(XT_SYNPROXY_OPT_WSCALE |
|
|
|
|
XT_SYNPROXY_OPT_SACK_PERM |
|
|
|
|
XT_SYNPROXY_OPT_ECN);
|
|
|
|
|
2016-03-26 08:32:57 +00:00
|
|
|
synproxy_send_client_synack(net, skb, th, &opts);
|
2017-04-20 06:01:45 +00:00
|
|
|
consume_skb(skb);
|
|
|
|
return NF_STOLEN;
|
2013-08-29 10:18:46 +00:00
|
|
|
} else if (th->ack && !(th->fin || th->rst || th->syn)) {
|
2013-08-27 06:50:14 +00:00
|
|
|
/* ACK from client */
|
2017-04-20 06:01:45 +00:00
|
|
|
if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) {
|
|
|
|
consume_skb(skb);
|
|
|
|
return NF_STOLEN;
|
|
|
|
} else {
|
|
|
|
return NF_DROP;
|
|
|
|
}
|
2013-08-29 10:18:46 +00:00
|
|
|
}
|
2013-08-27 06:50:14 +00:00
|
|
|
|
2013-08-29 10:18:46 +00:00
|
|
|
return XT_CONTINUE;
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
2015-09-18 19:33:06 +00:00
|
|
|
static unsigned int ipv4_synproxy_hook(void *priv,
|
2013-08-27 06:50:14 +00:00
|
|
|
struct sk_buff *skb,
|
2015-04-04 00:32:56 +00:00
|
|
|
const struct nf_hook_state *nhs)
|
2013-08-27 06:50:14 +00:00
|
|
|
{
|
2016-03-26 08:32:57 +00:00
|
|
|
struct net *net = nhs->net;
|
|
|
|
struct synproxy_net *snet = synproxy_pernet(net);
|
2013-08-27 06:50:14 +00:00
|
|
|
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))
|
|
|
|
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:
|
2013-09-30 07:51:46 +00:00
|
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
|
|
return NF_DROP;
|
2013-08-27 06:50:14 +00:00
|
|
|
|
|
|
|
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.
|
|
|
|
*/
|
2016-03-26 08:32:57 +00:00
|
|
|
if (synproxy_recv_client_ack(net, skb, th, &opts,
|
2017-04-20 06:01:45 +00:00
|
|
|
ntohl(th->seq) + 1)) {
|
2013-08-27 06:50:14 +00:00
|
|
|
this_cpu_inc(snet->stats->cookie_retrans);
|
2017-04-20 06:01:45 +00:00
|
|
|
consume_skb(skb);
|
|
|
|
return NF_STOLEN;
|
|
|
|
} else {
|
|
|
|
return NF_DROP;
|
|
|
|
}
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
synproxy->isn = ntohl(th->ack_seq);
|
|
|
|
if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
|
|
|
|
synproxy->its = opts.tsecr;
|
|
|
|
break;
|
|
|
|
case TCP_CONNTRACK_SYN_RECV:
|
|
|
|
if (!th->syn || !th->ack)
|
|
|
|
break;
|
|
|
|
|
2013-09-30 07:51:46 +00:00
|
|
|
if (!synproxy_parse_options(skb, thoff, th, &opts))
|
|
|
|
return NF_DROP;
|
|
|
|
|
2013-08-27 06:50:14 +00:00
|
|
|
if (opts.options & XT_SYNPROXY_OPT_TIMESTAMP)
|
|
|
|
synproxy->tsoff = opts.tsval - synproxy->its;
|
|
|
|
|
|
|
|
opts.options &= ~(XT_SYNPROXY_OPT_MSS |
|
|
|
|
XT_SYNPROXY_OPT_WSCALE |
|
|
|
|
XT_SYNPROXY_OPT_SACK_PERM);
|
|
|
|
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
2016-03-26 08:32:57 +00:00
|
|
|
synproxy_send_server_ack(net, state, skb, th, &opts);
|
2013-08-27 06:50:14 +00:00
|
|
|
|
|
|
|
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
|
|
|
|
|
|
|
|
swap(opts.tsval, opts.tsecr);
|
2016-03-26 08:32:57 +00:00
|
|
|
synproxy_send_client_ack(net, skb, th, &opts);
|
2013-08-27 06:50:14 +00:00
|
|
|
|
|
|
|
consume_skb(skb);
|
|
|
|
return NF_STOLEN;
|
|
|
|
default:
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
synproxy_tstamp_adjust(skb, thoff, th, ct, ctinfo, synproxy);
|
|
|
|
return NF_ACCEPT;
|
|
|
|
}
|
|
|
|
|
2017-07-26 09:40:52 +00:00
|
|
|
static const struct nf_hook_ops ipv4_synproxy_ops[] = {
|
2017-04-19 16:14:04 +00:00
|
|
|
{
|
|
|
|
.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,
|
|
|
|
},
|
|
|
|
};
|
|
|
|
|
2013-08-27 06:50:14 +00:00
|
|
|
static int synproxy_tg4_check(const struct xt_tgchk_param *par)
|
|
|
|
{
|
2017-04-19 16:14:04 +00:00
|
|
|
struct synproxy_net *snet = synproxy_pernet(par->net);
|
2013-08-27 06:50:14 +00:00
|
|
|
const struct ipt_entry *e = par->entryinfo;
|
2017-04-19 16:14:04 +00:00
|
|
|
int err;
|
2013-08-27 06:50:14 +00:00
|
|
|
|
|
|
|
if (e->ip.proto != IPPROTO_TCP ||
|
|
|
|
e->ip.invflags & XT_INV_PROTO)
|
|
|
|
return -EINVAL;
|
|
|
|
|
2017-04-19 16:14:04 +00:00
|
|
|
err = nf_ct_netns_get(par->net, par->family);
|
|
|
|
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;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
snet->hook_ref4++;
|
|
|
|
return err;
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
|
|
|
|
{
|
2017-04-19 16:14:04 +00:00
|
|
|
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));
|
2016-11-15 20:36:40 +00:00
|
|
|
nf_ct_netns_put(par->net, par->family);
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
static struct xt_target synproxy_tg4_reg __read_mostly = {
|
|
|
|
.name = "SYNPROXY",
|
|
|
|
.family = NFPROTO_IPV4,
|
2013-12-08 16:52:31 +00:00
|
|
|
.hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD),
|
2013-08-27 06:50:14 +00:00
|
|
|
.target = synproxy_tg4,
|
|
|
|
.targetsize = sizeof(struct xt_synproxy_info),
|
|
|
|
.checkentry = synproxy_tg4_check,
|
|
|
|
.destroy = synproxy_tg4_destroy,
|
|
|
|
.me = THIS_MODULE,
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init synproxy_tg4_init(void)
|
|
|
|
{
|
2017-04-19 16:14:04 +00:00
|
|
|
return xt_register_target(&synproxy_tg4_reg);
|
2013-08-27 06:50:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
static void __exit synproxy_tg4_exit(void)
|
|
|
|
{
|
|
|
|
xt_unregister_target(&synproxy_tg4_reg);
|
|
|
|
}
|
|
|
|
|
|
|
|
module_init(synproxy_tg4_init);
|
|
|
|
module_exit(synproxy_tg4_exit);
|
|
|
|
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
|