netfilter: nf_tables: add tunnel support

This patch implements the tunnel object type that can be used to
configure tunnels via metadata template through the existing lightweight
API from the ingress path.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 465 insertions, 0 deletions

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 55e399d5af10..654588088676 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -559,6 +559,12 @@ config NFT_NAT
 	  This option adds the "nat" expression that you can use to perform
 	  typical Network Address Translation (NAT) packet transformations.
 
+config NFT_TUNNEL
+	tristate "Netfilter nf_tables tunnel module"
+	help
+	  This option adds the "tunnel" expression that you can use to set
+	  tunneling policies.
+
 config NFT_OBJREF
 	tristate "Netfilter nf_tables stateful object reference module"
 	help
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index cf61615cc529..16895e045b66 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_NFT_QUEUE)		+= nft_queue.o
 obj-$(CONFIG_NFT_QUOTA)		+= nft_quota.o
 obj-$(CONFIG_NFT_REJECT) 	+= nft_reject.o
 obj-$(CONFIG_NFT_REJECT_INET)	+= nft_reject_inet.o
+obj-$(CONFIG_NFT_TUNNEL)	+= nft_tunnel.o
 obj-$(CONFIG_NFT_COUNTER)	+= nft_counter.o
 obj-$(CONFIG_NFT_LOG)		+= nft_log.o
 obj-$(CONFIG_NFT_MASQ)		+= nft_masq.o
diff --git a/net/netfilter/nft_tunnel.c b/net/netfilter/nft_tunnel.c
new file mode 100644
index 000000000000..715613d99c20
--- /dev/null
+++ b/net/netfilter/nft_tunnel.c
@@ -0,0 +1,458 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/seqlock.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/dst_metadata.h>
+#include <net/ip_tunnels.h>
+#include <net/vxlan.h>
+#include <net/erspan.h>
+
+struct nft_tunnel_opts {
+	union {
+		struct vxlan_metadata	vxlan;
+		struct erspan_metadata	erspan;
+	} u;
+	u32	len;
+	u32	flags;
+};
+
+struct nft_tunnel_obj {
+	struct metadata_dst	*md;
+	struct nft_tunnel_opts	opts;
+};
+
+static const struct nla_policy nft_tunnel_ip_policy[NFTA_TUNNEL_KEY_IP_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_IP_SRC]	= { .type = NLA_U32 },
+	[NFTA_TUNNEL_KEY_IP_DST]	= { .type = NLA_U32 },
+};
+
+static int nft_tunnel_obj_ip_init(const struct nft_ctx *ctx,
+				  const struct nlattr *attr,
+				  struct ip_tunnel_info *info)
+{
+	struct nlattr *tb[NFTA_TUNNEL_KEY_IP_MAX + 1];
+	int err;
+
+	err = nla_parse_nested(tb, NFTA_TUNNEL_KEY_IP_MAX, attr,
+			       nft_tunnel_ip_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (!tb[NFTA_TUNNEL_KEY_IP_DST])
+		return -EINVAL;
+
+	if (tb[NFTA_TUNNEL_KEY_IP_SRC])
+		info->key.u.ipv4.src = nla_get_be32(tb[NFTA_TUNNEL_KEY_IP_SRC]);
+	if (tb[NFTA_TUNNEL_KEY_IP_DST])
+		info->key.u.ipv4.dst = nla_get_be32(tb[NFTA_TUNNEL_KEY_IP_DST]);
+
+	return 0;
+}
+
+static const struct nla_policy nft_tunnel_ip6_policy[NFTA_TUNNEL_KEY_IP6_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_IP6_SRC]	= { .len = sizeof(struct in6_addr), },
+	[NFTA_TUNNEL_KEY_IP6_DST]	= { .len = sizeof(struct in6_addr), },
+	[NFTA_TUNNEL_KEY_IP6_FLOWLABEL]	= { .type = NLA_U32, }
+};
+
+static int nft_tunnel_obj_ip6_init(const struct nft_ctx *ctx,
+				   const struct nlattr *attr,
+				   struct ip_tunnel_info *info)
+{
+	struct nlattr *tb[NFTA_TUNNEL_KEY_IP6_MAX + 1];
+	int err;
+
+	err = nla_parse_nested(tb, NFTA_TUNNEL_KEY_IP6_MAX, attr,
+			       nft_tunnel_ip6_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (!tb[NFTA_TUNNEL_KEY_IP6_DST])
+		return -EINVAL;
+
+	if (tb[NFTA_TUNNEL_KEY_IP6_SRC]) {
+		memcpy(&info->key.u.ipv6.src,
+		       nla_data(tb[NFTA_TUNNEL_KEY_IP6_SRC]),
+		       sizeof(struct in6_addr));
+	}
+	if (tb[NFTA_TUNNEL_KEY_IP6_DST]) {
+		memcpy(&info->key.u.ipv6.dst,
+		       nla_data(tb[NFTA_TUNNEL_KEY_IP6_DST]),
+		       sizeof(struct in6_addr));
+	}
+	if (tb[NFTA_TUNNEL_KEY_IP6_FLOWLABEL])
+		info->key.label = nla_get_be32(tb[NFTA_TUNNEL_KEY_IP6_FLOWLABEL]);
+
+	info->mode |= IP_TUNNEL_INFO_IPV6;
+
+	return 0;
+}
+
+static const struct nla_policy nft_tunnel_opts_vxlan_policy[NFTA_TUNNEL_KEY_VXLAN_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_VXLAN_GBP]	= { .type = NLA_U32 },
+};
+
+static int nft_tunnel_obj_vxlan_init(const struct nlattr *attr,
+				     struct nft_tunnel_opts *opts)
+{
+	struct nlattr *tb[NFTA_TUNNEL_KEY_VXLAN_MAX + 1];
+	int err;
+
+	err = nla_parse_nested(tb, NFTA_TUNNEL_KEY_VXLAN_MAX, attr,
+			       nft_tunnel_opts_vxlan_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (!tb[NFTA_TUNNEL_KEY_VXLAN_GBP])
+		return -EINVAL;
+
+	opts->u.vxlan.gbp = ntohl(nla_get_be32(tb[NFTA_TUNNEL_KEY_VXLAN_GBP]));
+
+	opts->len	= sizeof(struct vxlan_metadata);
+	opts->flags	= TUNNEL_VXLAN_OPT;
+
+	return 0;
+}
+
+static const struct nla_policy nft_tunnel_opts_erspan_policy[NFTA_TUNNEL_KEY_ERSPAN_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_ERSPAN_V1_INDEX]	= { .type = NLA_U32 },
+	[NFTA_TUNNEL_KEY_ERSPAN_V2_DIR]	= { .type = NLA_U8 },
+	[NFTA_TUNNEL_KEY_ERSPAN_V2_HWID]	= { .type = NLA_U8 },
+};
+
+static int nft_tunnel_obj_erspan_init(const struct nlattr *attr,
+				      struct nft_tunnel_opts *opts)
+{
+	struct nlattr *tb[NFTA_TUNNEL_KEY_ERSPAN_MAX + 1];
+	uint8_t hwid, dir;
+	int err, version;
+
+	err = nla_parse_nested(tb, NFTA_TUNNEL_KEY_ERSPAN_MAX, attr,
+			       nft_tunnel_opts_erspan_policy, NULL);
+	if (err < 0)
+		return err;
+
+	version = ntohl(nla_get_be32(tb[NFTA_TUNNEL_KEY_ERSPAN_VERSION]));
+	switch (version) {
+	case ERSPAN_VERSION:
+		if (!tb[NFTA_TUNNEL_KEY_ERSPAN_V1_INDEX])
+			return -EINVAL;
+
+		opts->u.erspan.u.index =
+			nla_get_be32(tb[NFTA_TUNNEL_KEY_ERSPAN_V1_INDEX]);
+		break;
+	case ERSPAN_VERSION2:
+		if (!tb[NFTA_TUNNEL_KEY_ERSPAN_V2_DIR] ||
+		    !tb[NFTA_TUNNEL_KEY_ERSPAN_V2_HWID])
+			return -EINVAL;
+
+		hwid = nla_get_u8(tb[NFTA_TUNNEL_KEY_ERSPAN_V2_HWID]);
+		dir = nla_get_u8(tb[NFTA_TUNNEL_KEY_ERSPAN_V2_DIR]);
+
+		set_hwid(&opts->u.erspan.u.md2, hwid);
+		opts->u.erspan.u.md2.dir = dir;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	opts->u.erspan.version = version;
+
+	opts->len	= sizeof(struct erspan_metadata);
+	opts->flags	= TUNNEL_ERSPAN_OPT;
+
+	return 0;
+}
+
+static const struct nla_policy nft_tunnel_opts_policy[NFTA_TUNNEL_KEY_OPTS_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_OPTS_VXLAN]	= { .type = NLA_NESTED, },
+	[NFTA_TUNNEL_KEY_OPTS_ERSPAN]	= { .type = NLA_NESTED, },
+};
+
+static int nft_tunnel_obj_opts_init(const struct nft_ctx *ctx,
+				    const struct nlattr *attr,
+				    struct ip_tunnel_info *info,
+				    struct nft_tunnel_opts *opts)
+{
+	struct nlattr *tb[NFTA_TUNNEL_KEY_OPTS_MAX + 1];
+	int err;
+
+	err = nla_parse_nested(tb, NFTA_TUNNEL_KEY_OPTS_MAX, attr,
+			       nft_tunnel_opts_policy, NULL);
+	if (err < 0)
+		return err;
+
+	if (tb[NFTA_TUNNEL_KEY_OPTS_VXLAN]) {
+		err = nft_tunnel_obj_vxlan_init(tb[NFTA_TUNNEL_KEY_OPTS_VXLAN],
+						opts);
+	} else if (tb[NFTA_TUNNEL_KEY_OPTS_ERSPAN]) {
+		err = nft_tunnel_obj_erspan_init(tb[NFTA_TUNNEL_KEY_OPTS_ERSPAN],
+						 opts);
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	return err;
+}
+
+static const struct nla_policy nft_tunnel_key_policy[NFTA_TUNNEL_KEY_MAX + 1] = {
+	[NFTA_TUNNEL_KEY_IP]	= { .type = NLA_NESTED, },
+	[NFTA_TUNNEL_KEY_IP6]	= { .type = NLA_NESTED, },
+	[NFTA_TUNNEL_KEY_ID]	= { .type = NLA_U32, },
+	[NFTA_TUNNEL_KEY_FLAGS]	= { .type = NLA_U32, },
+	[NFTA_TUNNEL_KEY_TOS]	= { .type = NLA_U8, },
+	[NFTA_TUNNEL_KEY_TTL]	= { .type = NLA_U8, },
+	[NFTA_TUNNEL_KEY_OPTS]	= { .type = NLA_NESTED, },
+};
+
+static int nft_tunnel_obj_init(const struct nft_ctx *ctx,
+			       const struct nlattr * const tb[],
+			       struct nft_object *obj)
+{
+	struct nft_tunnel_obj *priv = nft_obj_data(obj);
+	struct ip_tunnel_info info;
+	struct metadata_dst *md;
+	int err;
+
+	if (!tb[NFTA_TUNNEL_KEY_ID])
+		return -EINVAL;
+
+	memset(&info, 0, sizeof(info));
+	info.mode		= IP_TUNNEL_INFO_TX;
+	info.key.tun_id		= key32_to_tunnel_id(nla_get_be32(tb[NFTA_TUNNEL_KEY_ID]));
+	info.key.tun_flags	= TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_NOCACHE;
+
+	if (tb[NFTA_TUNNEL_KEY_IP]) {
+		err = nft_tunnel_obj_ip_init(ctx, tb[NFTA_TUNNEL_KEY_IP], &info);
+		if (err < 0)
+			return err;
+	} else if (tb[NFTA_TUNNEL_KEY_IP6]) {
+		err = nft_tunnel_obj_ip6_init(ctx, tb[NFTA_TUNNEL_KEY_IP6], &info);
+		if (err < 0)
+			return err;
+	} else {
+		return -EINVAL;
+	}
+
+	if (tb[NFTA_TUNNEL_KEY_SPORT]) {
+		info.key.tp_src =
+			ntohs(nla_get_be16(tb[NFTA_TUNNEL_KEY_SPORT]));
+	}
+	if (tb[NFTA_TUNNEL_KEY_DPORT]) {
+		info.key.tp_dst =
+			ntohs(nla_get_be16(tb[NFTA_TUNNEL_KEY_DPORT]));
+	}
+
+	if (tb[NFTA_TUNNEL_KEY_FLAGS]) {
+		u32 tun_flags;
+
+		tun_flags = ntohl(nla_get_be32(tb[NFTA_TUNNEL_KEY_FLAGS]));
+		if (tun_flags & ~NFT_TUNNEL_F_MASK)
+			return -EOPNOTSUPP;
+
+		if (tun_flags & NFT_TUNNEL_F_ZERO_CSUM_TX)
+			info.key.tun_flags &= ~TUNNEL_CSUM;
+		if (tun_flags & NFT_TUNNEL_F_DONT_FRAGMENT)
+			info.key.tun_flags |= TUNNEL_DONT_FRAGMENT;
+		if (tun_flags & NFT_TUNNEL_F_SEQ_NUMBER)
+			info.key.tun_flags |= TUNNEL_SEQ;
+	}
+	if (tb[NFTA_TUNNEL_KEY_TOS])
+		info.key.tos = nla_get_u8(tb[NFTA_TUNNEL_KEY_TOS]);
+	if (tb[NFTA_TUNNEL_KEY_TTL])
+		info.key.ttl = nla_get_u8(tb[NFTA_TUNNEL_KEY_TTL]);
+	else
+		info.key.ttl = U8_MAX;
+
+	if (tb[NFTA_TUNNEL_KEY_OPTS]) {
+		err = nft_tunnel_obj_opts_init(ctx, tb[NFTA_TUNNEL_KEY_OPTS],
+					       &info, &priv->opts);
+		if (err < 0)
+			return err;
+	}
+
+	md = metadata_dst_alloc(priv->opts.len, METADATA_IP_TUNNEL, GFP_KERNEL);
+	if (!md)
+		return -ENOMEM;
+
+	memcpy(&md->u.tun_info, &info, sizeof(info));
+	ip_tunnel_info_opts_set(&md->u.tun_info, &priv->opts.u, priv->opts.len,
+				priv->opts.flags);
+	priv->md = md;
+
+	return 0;
+}
+
+static inline void nft_tunnel_obj_eval(struct nft_object *obj,
+				       struct nft_regs *regs,
+				       const struct nft_pktinfo *pkt)
+{
+	struct nft_tunnel_obj *priv = nft_obj_data(obj);
+	struct sk_buff *skb = pkt->skb;
+
+	skb_dst_drop(skb);
+	dst_hold((struct dst_entry *) priv->md);
+	skb_dst_set(skb, (struct dst_entry *) priv->md);
+}
+
+static int nft_tunnel_ip_dump(struct sk_buff *skb, struct ip_tunnel_info *info)
+{
+	struct nlattr *nest;
+
+	if (info->mode & IP_TUNNEL_INFO_IPV6) {
+		nest = nla_nest_start(skb, NFTA_TUNNEL_KEY_IP6);
+		if (!nest)
+			return -1;
+
+		if (nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_SRC, &info->key.u.ipv6.src) < 0 ||
+		    nla_put_in6_addr(skb, NFTA_TUNNEL_KEY_IP6_DST, &info->key.u.ipv6.dst) < 0 ||
+		    nla_put_be32(skb, NFTA_TUNNEL_KEY_IP6_FLOWLABEL, info->key.label))
+			return -1;
+
+		nla_nest_end(skb, nest);
+	} else {
+		nest = nla_nest_start(skb, NFTA_TUNNEL_KEY_IP);
+		if (!nest)
+			return -1;
+
+		if (nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_SRC, info->key.u.ipv4.src) < 0 ||
+		    nla_put_in_addr(skb, NFTA_TUNNEL_KEY_IP_DST, info->key.u.ipv4.dst) < 0)
+			return -1;
+
+		nla_nest_end(skb, nest);
+	}
+
+	return 0;
+}
+
+static int nft_tunnel_opts_dump(struct sk_buff *skb,
+				struct nft_tunnel_obj *priv)
+{
+	struct nft_tunnel_opts *opts = &priv->opts;
+	struct nlattr *nest;
+
+	nest = nla_nest_start(skb, NFTA_TUNNEL_KEY_OPTS);
+	if (!nest)
+		return -1;
+
+	if (opts->flags & TUNNEL_VXLAN_OPT) {
+		if (nla_put_be32(skb, NFTA_TUNNEL_KEY_VXLAN_GBP,
+				 htonl(opts->u.vxlan.gbp)))
+			return -1;
+	} else if (opts->flags & TUNNEL_ERSPAN_OPT) {
+		switch (opts->u.erspan.version) {
+		case ERSPAN_VERSION:
+			if (nla_put_be32(skb, NFTA_TUNNEL_KEY_ERSPAN_V1_INDEX,
+					 opts->u.erspan.u.index))
+				return -1;
+			break;
+		case ERSPAN_VERSION2:
+			if (nla_put_u8(skb, NFTA_TUNNEL_KEY_ERSPAN_V2_HWID,
+				       get_hwid(&opts->u.erspan.u.md2)) ||
+			    nla_put_u8(skb, NFTA_TUNNEL_KEY_ERSPAN_V2_DIR,
+				       opts->u.erspan.u.md2.dir))
+				return -1;
+			break;
+		}
+	}
+	nla_nest_end(skb, nest);
+
+	return 0;
+}
+
+static int nft_tunnel_ports_dump(struct sk_buff *skb,
+				 struct ip_tunnel_info *info)
+{
+	if (nla_put_be16(skb, NFTA_TUNNEL_KEY_SPORT, htons(info->key.tp_src)) < 0 ||
+	    nla_put_be16(skb, NFTA_TUNNEL_KEY_DPORT, htons(info->key.tp_dst)) < 0)
+		return -1;
+
+	return 0;
+}
+
+static int nft_tunnel_flags_dump(struct sk_buff *skb,
+				 struct ip_tunnel_info *info)
+{
+	u32 flags = 0;
+
+	if (info->key.tun_flags & TUNNEL_DONT_FRAGMENT)
+		flags |= NFT_TUNNEL_F_DONT_FRAGMENT;
+	if (!(info->key.tun_flags & TUNNEL_CSUM))
+		flags |= NFT_TUNNEL_F_ZERO_CSUM_TX;
+	if (info->key.tun_flags & TUNNEL_SEQ)
+		flags |= NFT_TUNNEL_F_SEQ_NUMBER;
+
+	if (nla_put_be32(skb, NFTA_TUNNEL_KEY_FLAGS, htonl(flags)) < 0)
+		return -1;
+
+	return 0;
+}
+
+static int nft_tunnel_obj_dump(struct sk_buff *skb,
+			       struct nft_object *obj, bool reset)
+{
+	struct nft_tunnel_obj *priv = nft_obj_data(obj);
+	struct ip_tunnel_info *info = &priv->md->u.tun_info;
+
+	if (nla_put_be32(skb, NFTA_TUNNEL_KEY_ID,
+			 tunnel_id_to_key32(info->key.tun_id)) ||
+	    nft_tunnel_ip_dump(skb, info) < 0 ||
+	    nft_tunnel_ports_dump(skb, info) < 0 ||
+	    nft_tunnel_flags_dump(skb, info) < 0 ||
+	    nla_put_u8(skb, NFTA_TUNNEL_KEY_TOS, info->key.tos) ||
+	    nla_put_u8(skb, NFTA_TUNNEL_KEY_TTL, info->key.ttl) ||
+	    nft_tunnel_opts_dump(skb, priv) < 0)
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -1;
+}
+
+static void nft_tunnel_obj_destroy(const struct nft_ctx *ctx,
+				   struct nft_object *obj)
+{
+	struct nft_tunnel_obj *priv = nft_obj_data(obj);
+
+	metadata_dst_free(priv->md);
+}
+
+static struct nft_object_type nft_tunnel_obj_type;
+static const struct nft_object_ops nft_tunnel_obj_ops = {
+	.type		= &nft_tunnel_obj_type,
+	.size		= sizeof(struct nft_tunnel_obj),
+	.eval		= nft_tunnel_obj_eval,
+	.init		= nft_tunnel_obj_init,
+	.destroy	= nft_tunnel_obj_destroy,
+	.dump		= nft_tunnel_obj_dump,
+};
+
+static struct nft_object_type nft_tunnel_obj_type __read_mostly = {
+	.type		= NFT_OBJECT_TUNNEL,
+	.ops		= &nft_tunnel_obj_ops,
+	.maxattr	= NFTA_TUNNEL_KEY_MAX,
+	.policy		= nft_tunnel_key_policy,
+	.owner		= THIS_MODULE,
+};
+
+static int __init nft_tunnel_module_init(void)
+{
+	return nft_register_obj(&nft_tunnel_obj_type);
+}
+
+static void __exit nft_tunnel_module_exit(void)
+{
+	nft_unregister_obj(&nft_tunnel_obj_type);
+}
+
+module_init(nft_tunnel_module_init);
+module_exit(nft_tunnel_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_TUNNEL);