Initial import

1 files changed, 447 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_proto_gre.c b/net/netfilter/nf_conntrack_proto_gre.c
new file mode 100644
index 000000000..7648674f2
--- /dev/null
+++ b/net/netfilter/nf_conntrack_proto_gre.c
@@ -0,0 +1,447 @@
+/*
+ * ip_conntrack_proto_gre.c - Version 3.0
+ *
+ * Connection tracking protocol helper module for GRE.
+ *
+ * GRE is a generic encapsulation protocol, which is generally not very
+ * suited for NAT, as it has no protocol-specific part as port numbers.
+ *
+ * It has an optional key field, which may help us distinguishing two
+ * connections between the same two hosts.
+ *
+ * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
+ *
+ * PPTP is built on top of a modified version of GRE, and has a mandatory
+ * field called "CallID", which serves us for the same purpose as the key
+ * field in plain GRE.
+ *
+ * Documentation about PPTP can be found in RFC 2637
+ *
+ * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ *
+ * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/timer.h>
+#include <linux/list.h>
+#include <linux/seq_file.h>
+#include <linux/in.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/dst.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/netfilter/nf_conntrack_l4proto.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <linux/netfilter/nf_conntrack_proto_gre.h>
+#include <linux/netfilter/nf_conntrack_pptp.h>
+
+enum grep_conntrack {
+	GRE_CT_UNREPLIED,
+	GRE_CT_REPLIED,
+	GRE_CT_MAX
+};
+
+static unsigned int gre_timeouts[GRE_CT_MAX] = {
+	[GRE_CT_UNREPLIED]	= 30*HZ,
+	[GRE_CT_REPLIED]	= 180*HZ,
+};
+
+static int proto_gre_net_id __read_mostly;
+struct netns_proto_gre {
+	struct nf_proto_net	nf;
+	rwlock_t		keymap_lock;
+	struct list_head	keymap_list;
+	unsigned int		gre_timeouts[GRE_CT_MAX];
+};
+
+static inline struct netns_proto_gre *gre_pernet(struct net *net)
+{
+	return net_generic(net, proto_gre_net_id);
+}
+
+static void nf_ct_gre_keymap_flush(struct net *net)
+{
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+	struct nf_ct_gre_keymap *km, *tmp;
+
+	write_lock_bh(&net_gre->keymap_lock);
+	list_for_each_entry_safe(km, tmp, &net_gre->keymap_list, list) {
+		list_del(&km->list);
+		kfree(km);
+	}
+	write_unlock_bh(&net_gre->keymap_lock);
+}
+
+static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
+				const struct nf_conntrack_tuple *t)
+{
+	return km->tuple.src.l3num == t->src.l3num &&
+	       !memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
+	       !memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
+	       km->tuple.dst.protonum == t->dst.protonum &&
+	       km->tuple.dst.u.all == t->dst.u.all;
+}
+
+/* look up the source key for a given tuple */
+static __be16 gre_keymap_lookup(struct net *net, struct nf_conntrack_tuple *t)
+{
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+	struct nf_ct_gre_keymap *km;
+	__be16 key = 0;
+
+	read_lock_bh(&net_gre->keymap_lock);
+	list_for_each_entry(km, &net_gre->keymap_list, list) {
+		if (gre_key_cmpfn(km, t)) {
+			key = km->tuple.src.u.gre.key;
+			break;
+		}
+	}
+	read_unlock_bh(&net_gre->keymap_lock);
+
+	pr_debug("lookup src key 0x%x for ", key);
+	nf_ct_dump_tuple(t);
+
+	return key;
+}
+
+/* add a single keymap entry, associate with specified master ct */
+int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
+			 struct nf_conntrack_tuple *t)
+{
+	struct net *net = nf_ct_net(ct);
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+	struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
+	struct nf_ct_gre_keymap **kmp, *km;
+
+	kmp = &ct_pptp_info->keymap[dir];
+	if (*kmp) {
+		/* check whether it's a retransmission */
+		read_lock_bh(&net_gre->keymap_lock);
+		list_for_each_entry(km, &net_gre->keymap_list, list) {
+			if (gre_key_cmpfn(km, t) && km == *kmp) {
+				read_unlock_bh(&net_gre->keymap_lock);
+				return 0;
+			}
+		}
+		read_unlock_bh(&net_gre->keymap_lock);
+		pr_debug("trying to override keymap_%s for ct %p\n",
+			 dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
+		return -EEXIST;
+	}
+
+	km = kmalloc(sizeof(*km), GFP_ATOMIC);
+	if (!km)
+		return -ENOMEM;
+	memcpy(&km->tuple, t, sizeof(*t));
+	*kmp = km;
+
+	pr_debug("adding new entry %p: ", km);
+	nf_ct_dump_tuple(&km->tuple);
+
+	write_lock_bh(&net_gre->keymap_lock);
+	list_add_tail(&km->list, &net_gre->keymap_list);
+	write_unlock_bh(&net_gre->keymap_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
+
+/* destroy the keymap entries associated with specified master ct */
+void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
+{
+	struct net *net = nf_ct_net(ct);
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+	struct nf_ct_pptp_master *ct_pptp_info = nfct_help_data(ct);
+	enum ip_conntrack_dir dir;
+
+	pr_debug("entering for ct %p\n", ct);
+
+	write_lock_bh(&net_gre->keymap_lock);
+	for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
+		if (ct_pptp_info->keymap[dir]) {
+			pr_debug("removing %p from list\n",
+				 ct_pptp_info->keymap[dir]);
+			list_del(&ct_pptp_info->keymap[dir]->list);
+			kfree(ct_pptp_info->keymap[dir]);
+			ct_pptp_info->keymap[dir] = NULL;
+		}
+	}
+	write_unlock_bh(&net_gre->keymap_lock);
+}
+EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
+
+/* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
+
+/* invert gre part of tuple */
+static bool gre_invert_tuple(struct nf_conntrack_tuple *tuple,
+			     const struct nf_conntrack_tuple *orig)
+{
+	tuple->dst.u.gre.key = orig->src.u.gre.key;
+	tuple->src.u.gre.key = orig->dst.u.gre.key;
+	return true;
+}
+
+/* gre hdr info to tuple */
+static bool gre_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
+			     struct nf_conntrack_tuple *tuple)
+{
+	struct net *net = dev_net(skb->dev ? skb->dev : skb_dst(skb)->dev);
+	const struct gre_hdr_pptp *pgrehdr;
+	struct gre_hdr_pptp _pgrehdr;
+	__be16 srckey;
+	const struct gre_hdr *grehdr;
+	struct gre_hdr _grehdr;
+
+	/* first only delinearize old RFC1701 GRE header */
+	grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
+	if (!grehdr || grehdr->version != GRE_VERSION_PPTP) {
+		/* try to behave like "nf_conntrack_proto_generic" */
+		tuple->src.u.all = 0;
+		tuple->dst.u.all = 0;
+		return true;
+	}
+
+	/* PPTP header is variable length, only need up to the call_id field */
+	pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
+	if (!pgrehdr)
+		return true;
+
+	if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
+		pr_debug("GRE_VERSION_PPTP but unknown proto\n");
+		return false;
+	}
+
+	tuple->dst.u.gre.key = pgrehdr->call_id;
+	srckey = gre_keymap_lookup(net, tuple);
+	tuple->src.u.gre.key = srckey;
+
+	return true;
+}
+
+/* print gre part of tuple */
+static void gre_print_tuple(struct seq_file *s,
+			    const struct nf_conntrack_tuple *tuple)
+{
+	seq_printf(s, "srckey=0x%x dstkey=0x%x ",
+		   ntohs(tuple->src.u.gre.key),
+		   ntohs(tuple->dst.u.gre.key));
+}
+
+/* print private data for conntrack */
+static void gre_print_conntrack(struct seq_file *s, struct nf_conn *ct)
+{
+	seq_printf(s, "timeout=%u, stream_timeout=%u ",
+		   (ct->proto.gre.timeout / HZ),
+		   (ct->proto.gre.stream_timeout / HZ));
+}
+
+static unsigned int *gre_get_timeouts(struct net *net)
+{
+	return gre_pernet(net)->gre_timeouts;
+}
+
+/* Returns verdict for packet, and may modify conntrack */
+static int gre_packet(struct nf_conn *ct,
+		      const struct sk_buff *skb,
+		      unsigned int dataoff,
+		      enum ip_conntrack_info ctinfo,
+		      u_int8_t pf,
+		      unsigned int hooknum,
+		      unsigned int *timeouts)
+{
+	/* If we've seen traffic both ways, this is a GRE connection.
+	 * Extend timeout. */
+	if (ct->status & IPS_SEEN_REPLY) {
+		nf_ct_refresh_acct(ct, ctinfo, skb,
+				   ct->proto.gre.stream_timeout);
+		/* Also, more likely to be important, and not a probe. */
+		if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
+			nf_conntrack_event_cache(IPCT_ASSURED, ct);
+	} else
+		nf_ct_refresh_acct(ct, ctinfo, skb,
+				   ct->proto.gre.timeout);
+
+	return NF_ACCEPT;
+}
+
+/* Called when a new connection for this protocol found. */
+static bool gre_new(struct nf_conn *ct, const struct sk_buff *skb,
+		    unsigned int dataoff, unsigned int *timeouts)
+{
+	pr_debug(": ");
+	nf_ct_dump_tuple(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
+
+	/* initialize to sane value.  Ideally a conntrack helper
+	 * (e.g. in case of pptp) is increasing them */
+	ct->proto.gre.stream_timeout = timeouts[GRE_CT_REPLIED];
+	ct->proto.gre.timeout = timeouts[GRE_CT_UNREPLIED];
+
+	return true;
+}
+
+/* Called when a conntrack entry has already been removed from the hashes
+ * and is about to be deleted from memory */
+static void gre_destroy(struct nf_conn *ct)
+{
+	struct nf_conn *master = ct->master;
+	pr_debug(" entering\n");
+
+	if (!master)
+		pr_debug("no master !?!\n");
+	else
+		nf_ct_gre_keymap_destroy(master);
+}
+
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nfnetlink_cttimeout.h>
+
+static int gre_timeout_nlattr_to_obj(struct nlattr *tb[],
+				     struct net *net, void *data)
+{
+	unsigned int *timeouts = data;
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+
+	/* set default timeouts for GRE. */
+	timeouts[GRE_CT_UNREPLIED] = net_gre->gre_timeouts[GRE_CT_UNREPLIED];
+	timeouts[GRE_CT_REPLIED] = net_gre->gre_timeouts[GRE_CT_REPLIED];
+
+	if (tb[CTA_TIMEOUT_GRE_UNREPLIED]) {
+		timeouts[GRE_CT_UNREPLIED] =
+			ntohl(nla_get_be32(tb[CTA_TIMEOUT_GRE_UNREPLIED])) * HZ;
+	}
+	if (tb[CTA_TIMEOUT_GRE_REPLIED]) {
+		timeouts[GRE_CT_REPLIED] =
+			ntohl(nla_get_be32(tb[CTA_TIMEOUT_GRE_REPLIED])) * HZ;
+	}
+	return 0;
+}
+
+static int
+gre_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
+{
+	const unsigned int *timeouts = data;
+
+	if (nla_put_be32(skb, CTA_TIMEOUT_GRE_UNREPLIED,
+			 htonl(timeouts[GRE_CT_UNREPLIED] / HZ)) ||
+	    nla_put_be32(skb, CTA_TIMEOUT_GRE_REPLIED,
+			 htonl(timeouts[GRE_CT_REPLIED] / HZ)))
+		goto nla_put_failure;
+	return 0;
+
+nla_put_failure:
+	return -ENOSPC;
+}
+
+static const struct nla_policy
+gre_timeout_nla_policy[CTA_TIMEOUT_GRE_MAX+1] = {
+	[CTA_TIMEOUT_GRE_UNREPLIED]	= { .type = NLA_U32 },
+	[CTA_TIMEOUT_GRE_REPLIED]	= { .type = NLA_U32 },
+};
+#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
+
+static int gre_init_net(struct net *net, u_int16_t proto)
+{
+	struct netns_proto_gre *net_gre = gre_pernet(net);
+	int i;
+
+	rwlock_init(&net_gre->keymap_lock);
+	INIT_LIST_HEAD(&net_gre->keymap_list);
+	for (i = 0; i < GRE_CT_MAX; i++)
+		net_gre->gre_timeouts[i] = gre_timeouts[i];
+
+	return 0;
+}
+
+/* protocol helper struct */
+static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 __read_mostly = {
+	.l3proto	 = AF_INET,
+	.l4proto	 = IPPROTO_GRE,
+	.name		 = "gre",
+	.pkt_to_tuple	 = gre_pkt_to_tuple,
+	.invert_tuple	 = gre_invert_tuple,
+	.print_tuple	 = gre_print_tuple,
+	.print_conntrack = gre_print_conntrack,
+	.get_timeouts    = gre_get_timeouts,
+	.packet		 = gre_packet,
+	.new		 = gre_new,
+	.destroy	 = gre_destroy,
+	.me 		 = THIS_MODULE,
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+	.tuple_to_nlattr = nf_ct_port_tuple_to_nlattr,
+	.nlattr_tuple_size = nf_ct_port_nlattr_tuple_size,
+	.nlattr_to_tuple = nf_ct_port_nlattr_to_tuple,
+	.nla_policy	 = nf_ct_port_nla_policy,
+#endif
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
+	.ctnl_timeout    = {
+		.nlattr_to_obj	= gre_timeout_nlattr_to_obj,
+		.obj_to_nlattr	= gre_timeout_obj_to_nlattr,
+		.nlattr_max	= CTA_TIMEOUT_GRE_MAX,
+		.obj_size	= sizeof(unsigned int) * GRE_CT_MAX,
+		.nla_policy	= gre_timeout_nla_policy,
+	},
+#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
+	.net_id		= &proto_gre_net_id,
+	.init_net	= gre_init_net,
+};
+
+static int proto_gre_net_init(struct net *net)
+{
+	int ret = 0;
+	ret = nf_ct_l4proto_pernet_register(net, &nf_conntrack_l4proto_gre4);
+	if (ret < 0)
+		pr_err("nf_conntrack_gre4: pernet registration failed.\n");
+	return ret;
+}
+
+static void proto_gre_net_exit(struct net *net)
+{
+	nf_ct_l4proto_pernet_unregister(net, &nf_conntrack_l4proto_gre4);
+	nf_ct_gre_keymap_flush(net);
+}
+
+static struct pernet_operations proto_gre_net_ops = {
+	.init = proto_gre_net_init,
+	.exit = proto_gre_net_exit,
+	.id   = &proto_gre_net_id,
+	.size = sizeof(struct netns_proto_gre),
+};
+
+static int __init nf_ct_proto_gre_init(void)
+{
+	int ret;
+
+	ret = register_pernet_subsys(&proto_gre_net_ops);
+	if (ret < 0)
+		goto out_pernet;
+
+	ret = nf_ct_l4proto_register(&nf_conntrack_l4proto_gre4);
+	if (ret < 0)
+		goto out_gre4;
+
+	return 0;
+out_gre4:
+	unregister_pernet_subsys(&proto_gre_net_ops);
+out_pernet:
+	return ret;
+}
+
+static void __exit nf_ct_proto_gre_fini(void)
+{
+	nf_ct_l4proto_unregister(&nf_conntrack_l4proto_gre4);
+	unregister_pernet_subsys(&proto_gre_net_ops);
+}
+
+module_init(nf_ct_proto_gre_init);
+module_exit(nf_ct_proto_gre_fini);
+
+MODULE_LICENSE("GPL");