1 files changed, 432 insertions, 0 deletions

diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c
new file mode 100644
index 000000000000..d23dc791aca7
--- /dev/null
+++ b/net/netfilter/nf_synproxy_core.c
@@ -0,0 +1,432 @@
+/*
+ * 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 <asm/unaligned.h>
+#include <net/tcp.h>
+#include <net/netns/generic.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 <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_extend.h>
+#include <net/netfilter/nf_conntrack_seqadj.h>
+#include <net/netfilter/nf_conntrack_synproxy.h>
+
+int synproxy_net_id;
+EXPORT_SYMBOL_GPL(synproxy_net_id);
+
+void
+synproxy_parse_options(const struct sk_buff *skb, unsigned int doff,
+		       const struct tcphdr *th, struct synproxy_options *opts)
+{
+	int length = (th->doff * 4) - sizeof(*th);
+	u8 buf[40], *ptr;
+
+	ptr = skb_header_pointer(skb, doff + sizeof(*th), length, buf);
+	BUG_ON(ptr == NULL);
+
+	opts->options = 0;
+	while (length > 0) {
+		int opcode = *ptr++;
+		int opsize;
+
+		switch (opcode) {
+		case TCPOPT_EOL:
+			return;
+		case TCPOPT_NOP:
+			length--;
+			continue;
+		default:
+			opsize = *ptr++;
+			if (opsize < 2)
+				return;
+			if (opsize > length)
+				return;
+
+			switch (opcode) {
+			case TCPOPT_MSS:
+				if (opsize == TCPOLEN_MSS) {
+					opts->mss = get_unaligned_be16(ptr);
+					opts->options |= XT_SYNPROXY_OPT_MSS;
+				}
+				break;
+			case TCPOPT_WINDOW:
+				if (opsize == TCPOLEN_WINDOW) {
+					opts->wscale = *ptr;
+					if (opts->wscale > 14)
+						opts->wscale = 14;
+					opts->options |= XT_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;
+				}
+				break;
+			case TCPOPT_SACK_PERM:
+				if (opsize == TCPOLEN_SACK_PERM)
+					opts->options |= XT_SYNPROXY_OPT_SACK_PERM;
+				break;
+			}
+
+			ptr += opsize - 2;
+			length -= opsize;
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(synproxy_parse_options);
+
+unsigned int synproxy_options_size(const struct synproxy_options *opts)
+{
+	unsigned int size = 0;
+
+	if (opts->options & XT_SYNPROXY_OPT_MSS)
+		size += TCPOLEN_MSS_ALIGNED;
+	if (opts->options & XT_SYNPROXY_OPT_TIMESTAMP)
+		size += TCPOLEN_TSTAMP_ALIGNED;
+	else if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
+		size += TCPOLEN_SACKPERM_ALIGNED;
+	if (opts->options & XT_SYNPROXY_OPT_WSCALE)
+		size += TCPOLEN_WSCALE_ALIGNED;
+
+	return size;
+}
+EXPORT_SYMBOL_GPL(synproxy_options_size);
+
+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)
+		*ptr++ = htonl((TCPOPT_MSS << 24) |
+			       (TCPOLEN_MSS << 16) |
+			       opts->mss);
+
+	if (options & XT_SYNPROXY_OPT_TIMESTAMP) {
+		if (options & XT_SYNPROXY_OPT_SACK_PERM)
+			*ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
+				       (TCPOLEN_SACK_PERM << 16) |
+				       (TCPOPT_TIMESTAMP << 8) |
+				       TCPOLEN_TIMESTAMP);
+		else
+			*ptr++ = htonl((TCPOPT_NOP << 24) |
+				       (TCPOPT_NOP << 16) |
+				       (TCPOPT_TIMESTAMP << 8) |
+				       TCPOLEN_TIMESTAMP);
+
+		*ptr++ = htonl(opts->tsval);
+		*ptr++ = htonl(opts->tsecr);
+	} else if (options & XT_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)
+		*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,
+				    struct synproxy_options *opts)
+{
+	opts->tsecr = opts->tsval;
+	opts->tsval = tcp_time_stamp & ~0x3f;
+
+	if (opts->options & XT_SYNPROXY_OPT_WSCALE)
+		opts->tsval |= info->wscale;
+	else
+		opts->tsval |= 0xf;
+
+	if (opts->options & XT_SYNPROXY_OPT_SACK_PERM)
+		opts->tsval |= 1 << 4;
+
+	if (opts->options & XT_SYNPROXY_OPT_ECN)
+		opts->tsval |= 1 << 5;
+}
+EXPORT_SYMBOL_GPL(synproxy_init_timestamp_cookie);
+
+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 |= opts->tsecr & (1 << 4) ? XT_SYNPROXY_OPT_SACK_PERM : 0;
+
+	opts->options |= opts->tsecr & (1 << 5) ? XT_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)
+{
+	unsigned int optoff, optend;
+	u32 *ptr, old;
+
+	if (synproxy->tsoff == 0)
+		return 1;
+
+	optoff = protoff + sizeof(struct tcphdr);
+	optend = protoff + th->doff * 4;
+
+	if (!skb_make_writable(skb, optend))
+		return 0;
+
+	while (optoff < optend) {
+		unsigned char *op = skb->data + optoff;
+
+		switch (op[0]) {
+		case TCPOPT_EOL:
+			return 1;
+		case TCPOPT_NOP:
+			optoff++;
+			continue;
+		default:
+			if (optoff + 1 == optend ||
+			    optoff + op[1] > optend ||
+			    op[1] < 2)
+				return 0;
+			if (op[0] == TCPOPT_TIMESTAMP &&
+			    op[1] == TCPOLEN_TIMESTAMP) {
+				if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
+					ptr = (u32 *)&op[2];
+					old = *ptr;
+					*ptr = htonl(ntohl(*ptr) -
+						     synproxy->tsoff);
+				} else {
+					ptr = (u32 *)&op[6];
+					old = *ptr;
+					*ptr = htonl(ntohl(*ptr) +
+						     synproxy->tsoff);
+				}
+				inet_proto_csum_replace4(&th->check, skb,
+							 old, *ptr, 0);
+				return 1;
+			}
+			optoff += op[1];
+		}
+	}
+	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),
+	.align		= __alignof__(struct nf_conn_synproxy),
+	.id		= NF_CT_EXT_SYNPROXY,
+};
+
+#ifdef CONFIG_PROC_FS
+static void *synproxy_cpu_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
+	int cpu;
+
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	for (cpu = *pos - 1; cpu < nr_cpu_ids; cpu++) {
+		if (!cpu_possible(cpu))
+			continue;
+		*pos = cpu + 1;
+		return per_cpu_ptr(snet->stats, cpu);
+	}
+
+	return NULL;
+}
+
+static void *synproxy_cpu_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct synproxy_net *snet = synproxy_pernet(seq_file_net(seq));
+	int cpu;
+
+	for (cpu = *pos; cpu < nr_cpu_ids; cpu++) {
+		if (!cpu_possible(cpu))
+			continue;
+		*pos = cpu + 1;
+		return per_cpu_ptr(snet->stats, cpu);
+	}
+
+	return NULL;
+}
+
+static void synproxy_cpu_seq_stop(struct seq_file *seq, void *v)
+{
+	return;
+}
+
+static int synproxy_cpu_seq_show(struct seq_file *seq, void *v)
+{
+	struct synproxy_stats *stats = v;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(seq, "entries\t\tsyn_received\t"
+				"cookie_invalid\tcookie_valid\t"
+				"cookie_retrans\tconn_reopened\n");
+		return 0;
+	}
+
+	seq_printf(seq, "%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", 0,
+		   stats->syn_received,
+		   stats->cookie_invalid,
+		   stats->cookie_valid,
+		   stats->cookie_retrans,
+		   stats->conn_reopened);
+
+	return 0;
+}
+
+static const struct seq_operations synproxy_cpu_seq_ops = {
+	.start		= synproxy_cpu_seq_start,
+	.next		= synproxy_cpu_seq_next,
+	.stop		= synproxy_cpu_seq_stop,
+	.show		= synproxy_cpu_seq_show,
+};
+
+static int synproxy_cpu_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open_net(inode, file, &synproxy_cpu_seq_ops,
+			    sizeof(struct seq_net_private));
+}
+
+static const struct file_operations synproxy_cpu_seq_fops = {
+	.owner		= THIS_MODULE,
+	.open		= synproxy_cpu_seq_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_net,
+};
+
+static int __net_init synproxy_proc_init(struct net *net)
+{
+	if (!proc_create("synproxy", S_IRUGO, net->proc_net_stat,
+			 &synproxy_cpu_seq_fops))
+		return -ENOMEM;
+	return 0;
+}
+
+static void __net_exit synproxy_proc_exit(struct net *net)
+{
+	remove_proc_entry("synproxy", net->proc_net_stat);
+}
+#else
+static int __net_init synproxy_proc_init(struct net *net)
+{
+	return 0;
+}
+
+static void __net_exit synproxy_proc_exit(struct net *net)
+{
+	return;
+}
+#endif /* CONFIG_PROC_FS */
+
+static int __net_init synproxy_net_init(struct net *net)
+{
+	struct synproxy_net *snet = synproxy_pernet(net);
+	struct nf_conntrack_tuple t;
+	struct nf_conn *ct;
+	int err = -ENOMEM;
+
+	memset(&t, 0, sizeof(t));
+	ct = nf_conntrack_alloc(net, 0, &t, &t, GFP_KERNEL);
+	if (IS_ERR(ct)) {
+		err = PTR_ERR(ct);
+		goto err1;
+	}
+
+	__set_bit(IPS_TEMPLATE_BIT, &ct->status);
+	__set_bit(IPS_CONFIRMED_BIT, &ct->status);
+	if (!nfct_seqadj_ext_add(ct))
+		goto err2;
+	if (!nfct_synproxy_ext_add(ct))
+		goto err2;
+
+	snet->tmpl = ct;
+
+	snet->stats = alloc_percpu(struct synproxy_stats);
+	if (snet->stats == NULL)
+		goto err2;
+
+	err = synproxy_proc_init(net);
+	if (err < 0)
+		goto err3;
+
+	return 0;
+
+err3:
+	free_percpu(snet->stats);
+err2:
+	nf_conntrack_free(ct);
+err1:
+	return err;
+}
+
+static void __net_exit synproxy_net_exit(struct net *net)
+{
+	struct synproxy_net *snet = synproxy_pernet(net);
+
+	nf_conntrack_free(snet->tmpl);
+	synproxy_proc_exit(net);
+	free_percpu(snet->stats);
+}
+
+static struct pernet_operations synproxy_net_ops = {
+	.init		= synproxy_net_init,
+	.exit		= synproxy_net_exit,
+	.id		= &synproxy_net_id,
+	.size		= sizeof(struct synproxy_net),
+};
+
+static int __init synproxy_core_init(void)
+{
+	int err;
+
+	err = nf_ct_extend_register(&nf_ct_synproxy_extend);
+	if (err < 0)
+		goto err1;
+
+	err = register_pernet_subsys(&synproxy_net_ops);
+	if (err < 0)
+		goto err2;
+
+	return 0;
+
+err2:
+	nf_ct_extend_unregister(&nf_ct_synproxy_extend);
+err1:
+	return err;
+}
+
+static void __exit synproxy_core_exit(void)
+{
+	unregister_pernet_subsys(&synproxy_net_ops);
+	nf_ct_extend_unregister(&nf_ct_synproxy_extend);
+}
+
+module_init(synproxy_core_init);
+module_exit(synproxy_core_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");