288 lines
7.4 KiB
C
288 lines
7.4 KiB
C
![]() |
// SPDX-License-Identifier: GPL-2.0
|
||
|
#include <linux/types.h>
|
||
|
#include <net/ip.h>
|
||
|
#include <net/tcp.h>
|
||
|
#include <net/netlink.h>
|
||
|
#include <net/netfilter/nf_tables.h>
|
||
|
#include <net/netfilter/nf_conntrack.h>
|
||
|
#include <net/netfilter/nf_conntrack_synproxy.h>
|
||
|
#include <net/netfilter/nf_synproxy.h>
|
||
|
#include <linux/netfilter/nf_tables.h>
|
||
|
#include <linux/netfilter/nf_synproxy.h>
|
||
|
|
||
|
struct nft_synproxy {
|
||
|
struct nf_synproxy_info info;
|
||
|
};
|
||
|
|
||
|
static const struct nla_policy nft_synproxy_policy[NFTA_SYNPROXY_MAX + 1] = {
|
||
|
[NFTA_SYNPROXY_MSS] = { .type = NLA_U16 },
|
||
|
[NFTA_SYNPROXY_WSCALE] = { .type = NLA_U8 },
|
||
|
[NFTA_SYNPROXY_FLAGS] = { .type = NLA_U32 },
|
||
|
};
|
||
|
|
||
|
static void nft_synproxy_tcp_options(struct synproxy_options *opts,
|
||
|
const struct tcphdr *tcp,
|
||
|
struct synproxy_net *snet,
|
||
|
struct nf_synproxy_info *info,
|
||
|
struct nft_synproxy *priv)
|
||
|
{
|
||
|
this_cpu_inc(snet->stats->syn_received);
|
||
|
if (tcp->ece && tcp->cwr)
|
||
|
opts->options |= NF_SYNPROXY_OPT_ECN;
|
||
|
|
||
|
opts->options &= priv->info.options;
|
||
|
if (opts->options & NF_SYNPROXY_OPT_TIMESTAMP)
|
||
|
synproxy_init_timestamp_cookie(info, opts);
|
||
|
else
|
||
|
opts->options &= ~(NF_SYNPROXY_OPT_WSCALE |
|
||
|
NF_SYNPROXY_OPT_SACK_PERM |
|
||
|
NF_SYNPROXY_OPT_ECN);
|
||
|
}
|
||
|
|
||
|
static void nft_synproxy_eval_v4(const struct nft_expr *expr,
|
||
|
struct nft_regs *regs,
|
||
|
const struct nft_pktinfo *pkt,
|
||
|
const struct tcphdr *tcp,
|
||
|
struct tcphdr *_tcph,
|
||
|
struct synproxy_options *opts)
|
||
|
{
|
||
|
struct nft_synproxy *priv = nft_expr_priv(expr);
|
||
|
struct nf_synproxy_info info = priv->info;
|
||
|
struct net *net = nft_net(pkt);
|
||
|
struct synproxy_net *snet = synproxy_pernet(net);
|
||
|
struct sk_buff *skb = pkt->skb;
|
||
|
|
||
|
if (tcp->syn) {
|
||
|
/* Initial SYN from client */
|
||
|
nft_synproxy_tcp_options(opts, tcp, snet, &info, priv);
|
||
|
synproxy_send_client_synack(net, skb, tcp, opts);
|
||
|
consume_skb(skb);
|
||
|
regs->verdict.code = NF_STOLEN;
|
||
|
} else if (tcp->ack) {
|
||
|
/* ACK from client */
|
||
|
if (synproxy_recv_client_ack(net, skb, tcp, opts,
|
||
|
ntohl(tcp->seq))) {
|
||
|
consume_skb(skb);
|
||
|
regs->verdict.code = NF_STOLEN;
|
||
|
} else {
|
||
|
regs->verdict.code = NF_DROP;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
|
||
|
static void nft_synproxy_eval_v6(const struct nft_expr *expr,
|
||
|
struct nft_regs *regs,
|
||
|
const struct nft_pktinfo *pkt,
|
||
|
const struct tcphdr *tcp,
|
||
|
struct tcphdr *_tcph,
|
||
|
struct synproxy_options *opts)
|
||
|
{
|
||
|
struct nft_synproxy *priv = nft_expr_priv(expr);
|
||
|
struct nf_synproxy_info info = priv->info;
|
||
|
struct net *net = nft_net(pkt);
|
||
|
struct synproxy_net *snet = synproxy_pernet(net);
|
||
|
struct sk_buff *skb = pkt->skb;
|
||
|
|
||
|
if (tcp->syn) {
|
||
|
/* Initial SYN from client */
|
||
|
nft_synproxy_tcp_options(opts, tcp, snet, &info, priv);
|
||
|
synproxy_send_client_synack_ipv6(net, skb, tcp, opts);
|
||
|
consume_skb(skb);
|
||
|
regs->verdict.code = NF_STOLEN;
|
||
|
} else if (tcp->ack) {
|
||
|
/* ACK from client */
|
||
|
if (synproxy_recv_client_ack_ipv6(net, skb, tcp, opts,
|
||
|
ntohl(tcp->seq))) {
|
||
|
consume_skb(skb);
|
||
|
regs->verdict.code = NF_STOLEN;
|
||
|
} else {
|
||
|
regs->verdict.code = NF_DROP;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
#endif /* CONFIG_NF_TABLES_IPV6*/
|
||
|
|
||
|
static void nft_synproxy_eval(const struct nft_expr *expr,
|
||
|
struct nft_regs *regs,
|
||
|
const struct nft_pktinfo *pkt)
|
||
|
{
|
||
|
struct synproxy_options opts = {};
|
||
|
struct sk_buff *skb = pkt->skb;
|
||
|
int thoff = pkt->xt.thoff;
|
||
|
const struct tcphdr *tcp;
|
||
|
struct tcphdr _tcph;
|
||
|
|
||
|
if (pkt->tprot != IPPROTO_TCP) {
|
||
|
regs->verdict.code = NFT_BREAK;
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
if (nf_ip_checksum(skb, nft_hook(pkt), thoff, IPPROTO_TCP)) {
|
||
|
regs->verdict.code = NF_DROP;
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
tcp = skb_header_pointer(skb, pkt->xt.thoff,
|
||
|
sizeof(struct tcphdr),
|
||
|
&_tcph);
|
||
|
if (!tcp) {
|
||
|
regs->verdict.code = NF_DROP;
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
if (!synproxy_parse_options(skb, thoff, tcp, &opts)) {
|
||
|
regs->verdict.code = NF_DROP;
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
switch (skb->protocol) {
|
||
|
case htons(ETH_P_IP):
|
||
|
nft_synproxy_eval_v4(expr, regs, pkt, tcp, &_tcph, &opts);
|
||
|
return;
|
||
|
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
|
||
|
case htons(ETH_P_IPV6):
|
||
|
nft_synproxy_eval_v6(expr, regs, pkt, tcp, &_tcph, &opts);
|
||
|
return;
|
||
|
#endif
|
||
|
}
|
||
|
regs->verdict.code = NFT_BREAK;
|
||
|
}
|
||
|
|
||
|
static int nft_synproxy_init(const struct nft_ctx *ctx,
|
||
|
const struct nft_expr *expr,
|
||
|
const struct nlattr * const tb[])
|
||
|
{
|
||
|
struct synproxy_net *snet = synproxy_pernet(ctx->net);
|
||
|
struct nft_synproxy *priv = nft_expr_priv(expr);
|
||
|
u32 flags;
|
||
|
int err;
|
||
|
|
||
|
if (tb[NFTA_SYNPROXY_MSS])
|
||
|
priv->info.mss = ntohs(nla_get_be16(tb[NFTA_SYNPROXY_MSS]));
|
||
|
if (tb[NFTA_SYNPROXY_WSCALE])
|
||
|
priv->info.wscale = nla_get_u8(tb[NFTA_SYNPROXY_WSCALE]);
|
||
|
if (tb[NFTA_SYNPROXY_FLAGS]) {
|
||
|
flags = ntohl(nla_get_be32(tb[NFTA_SYNPROXY_FLAGS]));
|
||
|
if (flags & ~NF_SYNPROXY_OPT_MASK)
|
||
|
return -EOPNOTSUPP;
|
||
|
priv->info.options = flags;
|
||
|
}
|
||
|
|
||
|
err = nf_ct_netns_get(ctx->net, ctx->family);
|
||
|
if (err)
|
||
|
return err;
|
||
|
|
||
|
switch (ctx->family) {
|
||
|
case NFPROTO_IPV4:
|
||
|
err = nf_synproxy_ipv4_init(snet, ctx->net);
|
||
|
if (err)
|
||
|
goto nf_ct_failure;
|
||
|
break;
|
||
|
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
|
||
|
case NFPROTO_IPV6:
|
||
|
err = nf_synproxy_ipv6_init(snet, ctx->net);
|
||
|
if (err)
|
||
|
goto nf_ct_failure;
|
||
|
break;
|
||
|
#endif
|
||
|
case NFPROTO_INET:
|
||
|
case NFPROTO_BRIDGE:
|
||
|
err = nf_synproxy_ipv4_init(snet, ctx->net);
|
||
|
if (err)
|
||
|
goto nf_ct_failure;
|
||
|
err = nf_synproxy_ipv6_init(snet, ctx->net);
|
||
|
if (err)
|
||
|
goto nf_ct_failure;
|
||
|
break;
|
||
|
}
|
||
|
|
||
|
return 0;
|
||
|
|
||
|
nf_ct_failure:
|
||
|
nf_ct_netns_put(ctx->net, ctx->family);
|
||
|
return err;
|
||
|
}
|
||
|
|
||
|
static void nft_synproxy_destroy(const struct nft_ctx *ctx,
|
||
|
const struct nft_expr *expr)
|
||
|
{
|
||
|
struct synproxy_net *snet = synproxy_pernet(ctx->net);
|
||
|
|
||
|
switch (ctx->family) {
|
||
|
case NFPROTO_IPV4:
|
||
|
nf_synproxy_ipv4_fini(snet, ctx->net);
|
||
|
break;
|
||
|
#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
|
||
|
case NFPROTO_IPV6:
|
||
|
nf_synproxy_ipv6_fini(snet, ctx->net);
|
||
|
break;
|
||
|
#endif
|
||
|
case NFPROTO_INET:
|
||
|
case NFPROTO_BRIDGE:
|
||
|
nf_synproxy_ipv4_fini(snet, ctx->net);
|
||
|
nf_synproxy_ipv6_fini(snet, ctx->net);
|
||
|
break;
|
||
|
}
|
||
|
nf_ct_netns_put(ctx->net, ctx->family);
|
||
|
}
|
||
|
|
||
|
static int nft_synproxy_dump(struct sk_buff *skb, const struct nft_expr *expr)
|
||
|
{
|
||
|
const struct nft_synproxy *priv = nft_expr_priv(expr);
|
||
|
|
||
|
if (nla_put_be16(skb, NFTA_SYNPROXY_MSS, htons(priv->info.mss)) ||
|
||
|
nla_put_u8(skb, NFTA_SYNPROXY_WSCALE, priv->info.wscale) ||
|
||
|
nla_put_be32(skb, NFTA_SYNPROXY_FLAGS, htonl(priv->info.options)))
|
||
|
goto nla_put_failure;
|
||
|
|
||
|
return 0;
|
||
|
|
||
|
nla_put_failure:
|
||
|
return -1;
|
||
|
}
|
||
|
|
||
|
static int nft_synproxy_validate(const struct nft_ctx *ctx,
|
||
|
const struct nft_expr *expr,
|
||
|
const struct nft_data **data)
|
||
|
{
|
||
|
return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
|
||
|
(1 << NF_INET_FORWARD));
|
||
|
}
|
||
|
|
||
|
static struct nft_expr_type nft_synproxy_type;
|
||
|
static const struct nft_expr_ops nft_synproxy_ops = {
|
||
|
.eval = nft_synproxy_eval,
|
||
|
.size = NFT_EXPR_SIZE(sizeof(struct nft_synproxy)),
|
||
|
.init = nft_synproxy_init,
|
||
|
.destroy = nft_synproxy_destroy,
|
||
|
.dump = nft_synproxy_dump,
|
||
|
.type = &nft_synproxy_type,
|
||
|
.validate = nft_synproxy_validate,
|
||
|
};
|
||
|
|
||
|
static struct nft_expr_type nft_synproxy_type __read_mostly = {
|
||
|
.ops = &nft_synproxy_ops,
|
||
|
.name = "synproxy",
|
||
|
.owner = THIS_MODULE,
|
||
|
.policy = nft_synproxy_policy,
|
||
|
.maxattr = NFTA_SYNPROXY_MAX,
|
||
|
};
|
||
|
|
||
|
static int __init nft_synproxy_module_init(void)
|
||
|
{
|
||
|
return nft_register_expr(&nft_synproxy_type);
|
||
|
}
|
||
|
|
||
|
static void __exit nft_synproxy_module_exit(void)
|
||
|
{
|
||
|
return nft_unregister_expr(&nft_synproxy_type);
|
||
|
}
|
||
|
|
||
|
module_init(nft_synproxy_module_init);
|
||
|
module_exit(nft_synproxy_module_exit);
|
||
|
|
||
|
MODULE_LICENSE("GPL");
|
||
|
MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
|
||
|
MODULE_ALIAS_NFT_EXPR("synproxy");
|