netfilter: conntrack: remove l3proto abstraction

This unifies ipv4 and ipv6 protocol trackers and removes the l3proto
abstraction.

This gets rid of all l3proto indirect calls and the need to do
a lookup on the function to call for l3 demux.

It increases module size by only a small amount (12kbyte), so this reduces
size because nf_conntrack.ko is useless without either nf_conntrack_ipv4
or nf_conntrack_ipv6 module.

before:
   text    data     bss     dec     hex filename
   7357    1088       0    8445    20fd nf_conntrack_ipv4.ko
   7405    1084       4    8493    212d nf_conntrack_ipv6.ko
  72614   13689     236   86539   1520b nf_conntrack.ko
 19K nf_conntrack_ipv4.ko
 19K nf_conntrack_ipv6.ko
179K nf_conntrack.ko

after:
   text    data     bss     dec     hex filename
  79277   13937     236   93450   16d0a nf_conntrack.ko
  191K nf_conntrack.ko

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 388 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_proto_icmp.c b/net/netfilter/nf_conntrack_proto_icmp.c
new file mode 100644
index 000000000000..036670b38282
--- /dev/null
+++ b/net/netfilter/nf_conntrack_proto_icmp.c
@@ -0,0 +1,388 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ * (C) 2006-2010 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/types.h>
+#include <linux/timer.h>
+#include <linux/netfilter.h>
+#include <linux/in.h>
+#include <linux/icmp.h>
+#include <linux/seq_file.h>
+#include <net/ip.h>
+#include <net/checksum.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/netfilter/nf_conntrack_tuple.h>
+#include <net/netfilter/nf_conntrack_l4proto.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_timeout.h>
+#include <net/netfilter/nf_conntrack_zones.h>
+#include <net/netfilter/nf_log.h>
+
+static const unsigned int nf_ct_icmp_timeout = 30*HZ;
+
+static inline struct nf_icmp_net *icmp_pernet(struct net *net)
+{
+	return &net->ct.nf_ct_proto.icmp;
+}
+
+static bool icmp_pkt_to_tuple(const struct sk_buff *skb, unsigned int dataoff,
+			      struct net *net, struct nf_conntrack_tuple *tuple)
+{
+	const struct icmphdr *hp;
+	struct icmphdr _hdr;
+
+	hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
+	if (hp == NULL)
+		return false;
+
+	tuple->dst.u.icmp.type = hp->type;
+	tuple->src.u.icmp.id = hp->un.echo.id;
+	tuple->dst.u.icmp.code = hp->code;
+
+	return true;
+}
+
+/* Add 1; spaces filled with 0. */
+static const u_int8_t invmap[] = {
+	[ICMP_ECHO] = ICMP_ECHOREPLY + 1,
+	[ICMP_ECHOREPLY] = ICMP_ECHO + 1,
+	[ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
+	[ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
+	[ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
+	[ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
+	[ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
+	[ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
+};
+
+static bool icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
+			      const struct nf_conntrack_tuple *orig)
+{
+	if (orig->dst.u.icmp.type >= sizeof(invmap) ||
+	    !invmap[orig->dst.u.icmp.type])
+		return false;
+
+	tuple->src.u.icmp.id = orig->src.u.icmp.id;
+	tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
+	tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
+	return true;
+}
+
+static unsigned int *icmp_get_timeouts(struct net *net)
+{
+	return &icmp_pernet(net)->timeout;
+}
+
+/* Returns verdict for packet, or -1 for invalid. */
+static int icmp_packet(struct nf_conn *ct,
+		       const struct sk_buff *skb,
+		       unsigned int dataoff,
+		       enum ip_conntrack_info ctinfo)
+{
+	/* Do not immediately delete the connection after the first
+	   successful reply to avoid excessive conntrackd traffic
+	   and also to handle correctly ICMP echo reply duplicates. */
+	unsigned int *timeout = nf_ct_timeout_lookup(ct);
+
+	if (!timeout)
+		timeout = icmp_get_timeouts(nf_ct_net(ct));
+
+	nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
+
+	return NF_ACCEPT;
+}
+
+/* Called when a new connection for this protocol found. */
+static bool icmp_new(struct nf_conn *ct, const struct sk_buff *skb,
+		     unsigned int dataoff)
+{
+	static const u_int8_t valid_new[] = {
+		[ICMP_ECHO] = 1,
+		[ICMP_TIMESTAMP] = 1,
+		[ICMP_INFO_REQUEST] = 1,
+		[ICMP_ADDRESS] = 1
+	};
+
+	if (ct->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new) ||
+	    !valid_new[ct->tuplehash[0].tuple.dst.u.icmp.type]) {
+		/* Can't create a new ICMP `conn' with this. */
+		pr_debug("icmp: can't create new conn with type %u\n",
+			 ct->tuplehash[0].tuple.dst.u.icmp.type);
+		nf_ct_dump_tuple_ip(&ct->tuplehash[0].tuple);
+		return false;
+	}
+	return true;
+}
+
+/* Returns conntrack if it dealt with ICMP, and filled in skb fields */
+static int
+icmp_error_message(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
+		 unsigned int hooknum)
+{
+	struct nf_conntrack_tuple innertuple, origtuple;
+	const struct nf_conntrack_l4proto *innerproto;
+	const struct nf_conntrack_tuple_hash *h;
+	const struct nf_conntrack_zone *zone;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conntrack_zone tmp;
+
+	WARN_ON(skb_nfct(skb));
+	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
+
+	/* Are they talking about one of our connections? */
+	if (!nf_ct_get_tuplepr(skb,
+			       skb_network_offset(skb) + ip_hdrlen(skb)
+						       + sizeof(struct icmphdr),
+			       PF_INET, net, &origtuple)) {
+		pr_debug("icmp_error_message: failed to get tuple\n");
+		return -NF_ACCEPT;
+	}
+
+	/* rcu_read_lock()ed by nf_hook_thresh */
+	innerproto = __nf_ct_l4proto_find(PF_INET, origtuple.dst.protonum);
+
+	/* Ordinarily, we'd expect the inverted tupleproto, but it's
+	   been preserved inside the ICMP. */
+	if (!nf_ct_invert_tuple(&innertuple, &origtuple, innerproto)) {
+		pr_debug("icmp_error_message: no match\n");
+		return -NF_ACCEPT;
+	}
+
+	ctinfo = IP_CT_RELATED;
+
+	h = nf_conntrack_find_get(net, zone, &innertuple);
+	if (!h) {
+		pr_debug("icmp_error_message: no match\n");
+		return -NF_ACCEPT;
+	}
+
+	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
+		ctinfo += IP_CT_IS_REPLY;
+
+	/* Update skb to refer to this connection */
+	nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
+	return NF_ACCEPT;
+}
+
+static void icmp_error_log(const struct sk_buff *skb, struct net *net,
+			   u8 pf, const char *msg)
+{
+	nf_l4proto_log_invalid(skb, net, pf, IPPROTO_ICMP, "%s", msg);
+}
+
+/* Small and modified version of icmp_rcv */
+static int
+icmp_error(struct net *net, struct nf_conn *tmpl,
+	   struct sk_buff *skb, unsigned int dataoff,
+	   u8 pf, unsigned int hooknum)
+{
+	const struct icmphdr *icmph;
+	struct icmphdr _ih;
+
+	/* Not enough header? */
+	icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
+	if (icmph == NULL) {
+		icmp_error_log(skb, net, pf, "short packet");
+		return -NF_ACCEPT;
+	}
+
+	/* See ip_conntrack_proto_tcp.c */
+	if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
+	    nf_ip_checksum(skb, hooknum, dataoff, 0)) {
+		icmp_error_log(skb, net, pf, "bad hw icmp checksum");
+		return -NF_ACCEPT;
+	}
+
+	/*
+	 *	18 is the highest 'known' ICMP type. Anything else is a mystery
+	 *
+	 *	RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
+	 *		  discarded.
+	 */
+	if (icmph->type > NR_ICMP_TYPES) {
+		icmp_error_log(skb, net, pf, "invalid icmp type");
+		return -NF_ACCEPT;
+	}
+
+	/* Need to track icmp error message? */
+	if (icmph->type != ICMP_DEST_UNREACH &&
+	    icmph->type != ICMP_SOURCE_QUENCH &&
+	    icmph->type != ICMP_TIME_EXCEEDED &&
+	    icmph->type != ICMP_PARAMETERPROB &&
+	    icmph->type != ICMP_REDIRECT)
+		return NF_ACCEPT;
+
+	return icmp_error_message(net, tmpl, skb, hooknum);
+}
+
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nfnetlink_conntrack.h>
+
+static int icmp_tuple_to_nlattr(struct sk_buff *skb,
+				const struct nf_conntrack_tuple *t)
+{
+	if (nla_put_be16(skb, CTA_PROTO_ICMP_ID, t->src.u.icmp.id) ||
+	    nla_put_u8(skb, CTA_PROTO_ICMP_TYPE, t->dst.u.icmp.type) ||
+	    nla_put_u8(skb, CTA_PROTO_ICMP_CODE, t->dst.u.icmp.code))
+		goto nla_put_failure;
+	return 0;
+
+nla_put_failure:
+	return -1;
+}
+
+static const struct nla_policy icmp_nla_policy[CTA_PROTO_MAX+1] = {
+	[CTA_PROTO_ICMP_TYPE]	= { .type = NLA_U8 },
+	[CTA_PROTO_ICMP_CODE]	= { .type = NLA_U8 },
+	[CTA_PROTO_ICMP_ID]	= { .type = NLA_U16 },
+};
+
+static int icmp_nlattr_to_tuple(struct nlattr *tb[],
+				struct nf_conntrack_tuple *tuple)
+{
+	if (!tb[CTA_PROTO_ICMP_TYPE] ||
+	    !tb[CTA_PROTO_ICMP_CODE] ||
+	    !tb[CTA_PROTO_ICMP_ID])
+		return -EINVAL;
+
+	tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMP_TYPE]);
+	tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMP_CODE]);
+	tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMP_ID]);
+
+	if (tuple->dst.u.icmp.type >= sizeof(invmap) ||
+	    !invmap[tuple->dst.u.icmp.type])
+		return -EINVAL;
+
+	return 0;
+}
+
+static unsigned int icmp_nlattr_tuple_size(void)
+{
+	static unsigned int size __read_mostly;
+
+	if (!size)
+		size = nla_policy_len(icmp_nla_policy, CTA_PROTO_MAX + 1);
+
+	return size;
+}
+#endif
+
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/nfnetlink_cttimeout.h>
+
+static int icmp_timeout_nlattr_to_obj(struct nlattr *tb[],
+				      struct net *net, void *data)
+{
+	unsigned int *timeout = data;
+	struct nf_icmp_net *in = icmp_pernet(net);
+
+	if (tb[CTA_TIMEOUT_ICMP_TIMEOUT]) {
+		if (!timeout)
+			timeout = &in->timeout;
+		*timeout =
+			ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMP_TIMEOUT])) * HZ;
+	} else if (timeout) {
+		/* Set default ICMP timeout. */
+		*timeout = in->timeout;
+	}
+	return 0;
+}
+
+static int
+icmp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
+{
+	const unsigned int *timeout = data;
+
+	if (nla_put_be32(skb, CTA_TIMEOUT_ICMP_TIMEOUT, htonl(*timeout / HZ)))
+		goto nla_put_failure;
+	return 0;
+
+nla_put_failure:
+	return -ENOSPC;
+}
+
+static const struct nla_policy
+icmp_timeout_nla_policy[CTA_TIMEOUT_ICMP_MAX+1] = {
+	[CTA_TIMEOUT_ICMP_TIMEOUT]	= { .type = NLA_U32 },
+};
+#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table icmp_sysctl_table[] = {
+	{
+		.procname	= "nf_conntrack_icmp_timeout",
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
+	{ }
+};
+#endif /* CONFIG_SYSCTL */
+
+static int icmp_kmemdup_sysctl_table(struct nf_proto_net *pn,
+				     struct nf_icmp_net *in)
+{
+#ifdef CONFIG_SYSCTL
+	pn->ctl_table = kmemdup(icmp_sysctl_table,
+				sizeof(icmp_sysctl_table),
+				GFP_KERNEL);
+	if (!pn->ctl_table)
+		return -ENOMEM;
+
+	pn->ctl_table[0].data = &in->timeout;
+#endif
+	return 0;
+}
+
+static int icmp_init_net(struct net *net, u_int16_t proto)
+{
+	struct nf_icmp_net *in = icmp_pernet(net);
+	struct nf_proto_net *pn = &in->pn;
+
+	in->timeout = nf_ct_icmp_timeout;
+
+	return icmp_kmemdup_sysctl_table(pn, in);
+}
+
+static struct nf_proto_net *icmp_get_net_proto(struct net *net)
+{
+	return &net->ct.nf_ct_proto.icmp.pn;
+}
+
+const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
+{
+	.l3proto		= PF_INET,
+	.l4proto		= IPPROTO_ICMP,
+	.pkt_to_tuple		= icmp_pkt_to_tuple,
+	.invert_tuple		= icmp_invert_tuple,
+	.packet			= icmp_packet,
+	.new			= icmp_new,
+	.error			= icmp_error,
+	.destroy		= NULL,
+	.me			= NULL,
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
+	.tuple_to_nlattr	= icmp_tuple_to_nlattr,
+	.nlattr_tuple_size	= icmp_nlattr_tuple_size,
+	.nlattr_to_tuple	= icmp_nlattr_to_tuple,
+	.nla_policy		= icmp_nla_policy,
+#endif
+#if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
+	.ctnl_timeout		= {
+		.nlattr_to_obj	= icmp_timeout_nlattr_to_obj,
+		.obj_to_nlattr	= icmp_timeout_obj_to_nlattr,
+		.nlattr_max	= CTA_TIMEOUT_ICMP_MAX,
+		.obj_size	= sizeof(unsigned int),
+		.nla_policy	= icmp_timeout_nla_policy,
+	},
+#endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
+	.init_net		= icmp_init_net,
+	.get_net_proto		= icmp_get_net_proto,
+};