Release 4.8 net/ipv4/netfilter/ipt_SYNPROXY.c
/*
* Copyright (c) 2013 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/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>
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 = (struct iphdr *)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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 117 | 91.41% | 1 | 25.00% |
liping zhang | liping zhang | 5 | 3.91% | 1 | 25.00% |
nikolay borisov | nikolay borisov | 4 | 3.12% | 1 | 25.00% |
eric dumazet | eric dumazet | 2 | 1.56% | 1 | 25.00% |
| Total | 128 | 100.00% | 4 | 100.00% |
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) {
nskb->nfct = nfct;
nskb->nfctinfo = ctinfo;
nf_conntrack_get(nfct);
}
ip_local_out(net, nskb->sk, nskb);
return;
free_nskb:
kfree_skb(nskb);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 160 | 92.49% | 1 | 16.67% |
eric w. biederman | eric w. biederman | 11 | 6.36% | 4 | 66.67% |
liping zhang | liping zhang | 2 | 1.16% | 1 | 16.67% |
| Total | 173 | 100.00% | 6 | 100.00% |
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 = (struct tcphdr *)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, IP_CT_ESTABLISHED_REPLY,
niph, nth, tcp_hdr_size);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 262 | 96.32% | 1 | 33.33% |
liping zhang | liping zhang | 5 | 1.84% | 1 | 33.33% |
eric w. biederman | eric w. biederman | 5 | 1.84% | 1 | 33.33% |
| Total | 272 | 100.00% | 3 | 100.00% |
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 = (struct tcphdr *)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);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 262 | 94.24% | 1 | 33.33% |
liping zhang | liping zhang | 15 | 5.40% | 1 | 33.33% |
eric w. biederman | eric w. biederman | 1 | 0.36% | 1 | 33.33% |
| Total | 278 | 100.00% | 3 | 100.00% |
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 = (struct tcphdr *)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);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 253 | 97.68% | 1 | 33.33% |
liping zhang | liping zhang | 5 | 1.93% | 1 | 33.33% |
eric w. biederman | eric w. biederman | 1 | 0.39% | 1 | 33.33% |
| Total | 259 | 100.00% | 3 | 100.00% |
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 = (struct tcphdr *)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, IP_CT_ESTABLISHED_REPLY,
niph, nth, tcp_hdr_size);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 239 | 95.22% | 1 | 20.00% |
liping zhang | liping zhang | 5 | 1.99% | 1 | 20.00% |
phil sutter | phil sutter | 4 | 1.59% | 1 | 20.00% |
eric dumazet | eric dumazet | 2 | 0.80% | 1 | 20.00% |
eric w. biederman | eric w. biederman | 1 | 0.40% | 1 | 20.00% |
| Total | 251 | 100.00% | 5 | 100.00% |
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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 116 | 85.93% | 1 | 33.33% |
liping zhang | liping zhang | 13 | 9.63% | 1 | 33.33% |
martin topholm | martin topholm | 6 | 4.44% | 1 | 33.33% |
| Total | 135 | 100.00% | 3 | 100.00% |
static unsigned int
synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_synproxy_info *info = par->targinfo;
struct net *net = par->net;
struct synproxy_net *snet = synproxy_pernet(net);
struct synproxy_options opts = {};
struct tcphdr *th, _th;
if (nf_ip_checksum(skb, par->hooknum, par->thoff, IPPROTO_TCP))
return NF_DROP;
th = skb_header_pointer(skb, par->thoff, sizeof(_th), &_th);
if (th == NULL)
return NF_DROP;
if (!synproxy_parse_options(skb, par->thoff, th, &opts))
return NF_DROP;
if (th->syn && !(th->ack || th->fin || th->rst)) {
/* 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);
synproxy_send_client_synack(net, skb, th, &opts);
return NF_DROP;
} else if (th->ack && !(th->fin || th->rst || th->syn)) {
/* ACK from client */
synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq));
return NF_DROP;
}
return XT_CONTINUE;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 245 | 87.50% | 2 | 28.57% |
jesper dangaard brouer | jesper dangaard brouer | 22 | 7.86% | 2 | 28.57% |
liping zhang | liping zhang | 11 | 3.93% | 1 | 14.29% |
eric w. biederman | eric w. biederman | 2 | 0.71% | 2 | 28.57% |
| Total | 280 | 100.00% | 7 | 100.00% |
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))
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);
return NF_DROP;
}
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;
if (!synproxy_parse_options(skb, thoff, th, &opts))
return NF_DROP;
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);
synproxy_send_server_ack(net, state, skb, th, &opts);
nf_ct_seqadj_init(ct, ctinfo, synproxy->isn - ntohl(th->seq));
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;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 510 | 96.77% | 3 | 42.86% |
liping zhang | liping zhang | 12 | 2.28% | 1 | 14.29% |
eric w. biederman | eric w. biederman | 3 | 0.57% | 2 | 28.57% |
david s. miller | david s. miller | 2 | 0.38% | 1 | 14.29% |
| Total | 527 | 100.00% | 7 | 100.00% |
static int synproxy_tg4_check(const struct xt_tgchk_param *par)
{
const struct ipt_entry *e = par->entryinfo;
if (e->ip.proto != IPPROTO_TCP ||
e->ip.invflags & XT_INV_PROTO)
return -EINVAL;
return nf_ct_l3proto_try_module_get(par->family);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 52 | 100.00% | 1 | 100.00% |
| Total | 52 | 100.00% | 1 | 100.00% |
static void synproxy_tg4_destroy(const struct xt_tgdtor_param *par)
{
nf_ct_l3proto_module_put(par->family);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 19 | 100.00% | 1 | 100.00% |
| Total | 19 | 100.00% | 1 | 100.00% |
static struct xt_target synproxy_tg4_reg __read_mostly = {
.name = "SYNPROXY",
.family = NFPROTO_IPV4,
.hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD),
.target = synproxy_tg4,
.targetsize = sizeof(struct xt_synproxy_info),
.checkentry = synproxy_tg4_check,
.destroy = synproxy_tg4_destroy,
.me = THIS_MODULE,
};
static struct nf_hook_ops ipv4_synproxy_ops[] __read_mostly = {
{
.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 __init synproxy_tg4_init(void)
{
int err;
err = nf_register_hooks(ipv4_synproxy_ops,
ARRAY_SIZE(ipv4_synproxy_ops));
if (err < 0)
goto err1;
err = xt_register_target(&synproxy_tg4_reg);
if (err < 0)
goto err2;
return 0;
err2:
nf_unregister_hooks(ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops));
err1:
return err;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 70 | 100.00% | 1 | 100.00% |
| Total | 70 | 100.00% | 1 | 100.00% |
static void __exit synproxy_tg4_exit(void)
{
xt_unregister_target(&synproxy_tg4_reg);
nf_unregister_hooks(ipv4_synproxy_ops, ARRAY_SIZE(ipv4_synproxy_ops));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 25 | 100.00% | 1 | 100.00% |
| Total | 25 | 100.00% | 1 | 100.00% |
module_init(synproxy_tg4_init);
module_exit(synproxy_tg4_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
patrick mchardy | patrick mchardy | 2497 | 94.73% | 4 | 21.05% |
liping zhang | liping zhang | 73 | 2.77% | 1 | 5.26% |
eric w. biederman | eric w. biederman | 24 | 0.91% | 7 | 36.84% |
jesper dangaard brouer | jesper dangaard brouer | 22 | 0.83% | 2 | 10.53% |
martin topholm | martin topholm | 6 | 0.23% | 1 | 5.26% |
eric dumazet | eric dumazet | 4 | 0.15% | 1 | 5.26% |
phil sutter | phil sutter | 4 | 0.15% | 1 | 5.26% |
nikolay borisov | nikolay borisov | 4 | 0.15% | 1 | 5.26% |
david s. miller | david s. miller | 2 | 0.08% | 1 | 5.26% |
| Total | 2636 | 100.00% | 19 | 100.00% |
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