diff options
Diffstat (limited to 'net/ipv6/netfilter/ip6t_SYNPROXY.c')
| -rw-r--r-- | net/ipv6/netfilter/ip6t_SYNPROXY.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c new file mode 100644 index 000000000..d51d0c3e5 --- /dev/null +++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c @@ -0,0 +1,124 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2013 Patrick McHardy <kaber@trash.net> + */ + +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter/xt_SYNPROXY.h> + +#include <net/netfilter/nf_synproxy.h> + +static unsigned int +synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par) +{ + const struct xt_synproxy_info *info = par->targinfo; + struct net *net = xt_net(par); + struct synproxy_net *snet = synproxy_pernet(net); + struct synproxy_options opts = {}; + struct tcphdr *th, _th; + + if (nf_ip6_checksum(skb, xt_hooknum(par), 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; + opts.mss_encode = opts.mss_option; + opts.mss_option = info->mss; + 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_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_ipv6(net, skb, th, &opts, + ntohl(th->seq))) { + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } + } + + return XT_CONTINUE; +} + +static int synproxy_tg6_check(const struct xt_tgchk_param *par) +{ + struct synproxy_net *snet = synproxy_pernet(par->net); + const struct ip6t_entry *e = par->entryinfo; + int err; + + if (!(e->ipv6.flags & IP6T_F_PROTO) || + e->ipv6.proto != IPPROTO_TCP || + e->ipv6.invflags & XT_INV_PROTO) + return -EINVAL; + + err = nf_ct_netns_get(par->net, par->family); + if (err) + return err; + + err = nf_synproxy_ipv6_init(snet, par->net); + if (err) { + nf_ct_netns_put(par->net, par->family); + return err; + } + + return err; +} + +static void synproxy_tg6_destroy(const struct xt_tgdtor_param *par) +{ + struct synproxy_net *snet = synproxy_pernet(par->net); + + nf_synproxy_ipv6_fini(snet, par->net); + nf_ct_netns_put(par->net, par->family); +} + +static struct xt_target synproxy_tg6_reg __read_mostly = { + .name = "SYNPROXY", + .family = NFPROTO_IPV6, + .hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD), + .target = synproxy_tg6, + .targetsize = sizeof(struct xt_synproxy_info), + .checkentry = synproxy_tg6_check, + .destroy = synproxy_tg6_destroy, + .me = THIS_MODULE, +}; + +static int __init synproxy_tg6_init(void) +{ + return xt_register_target(&synproxy_tg6_reg); +} + +static void __exit synproxy_tg6_exit(void) +{ + xt_unregister_target(&synproxy_tg6_reg); +} + +module_init(synproxy_tg6_init); +module_exit(synproxy_tg6_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); +MODULE_DESCRIPTION("Intercept IPv6 TCP connections and establish them using syncookies"); |