netfilter: nf_tables: add forward expression to the netdev family

You can use this to forward packets from ingress to the egress path of
the specified interface. This provides a fast path to bounce packets
from one interface to another specific destination interface.

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

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 22043ce95ae647077ed6e0da6567b5ba10307fca..731288a039f6f0c475c932ad38e79c862b1faf08 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -983,6 +983,18 @@ enum nft_dup_attributes {
 };
 #define NFTA_DUP_MAX           (__NFTA_DUP_MAX - 1)
 
+/**
+ * enum nft_fwd_attributes - nf_tables fwd expression netlink attributes
+ *
+ * @NFTA_FWD_SREG_DEV: source register of output interface (NLA_U32: nft_register)
+ */
+enum nft_fwd_attributes {
+       NFTA_FWD_UNSPEC,
+       NFTA_FWD_SREG_DEV,
+       __NFTA_FWD_MAX
+};
+#define NFTA_FWD_MAX   (__NFTA_FWD_MAX - 1)
+
 /**
  * enum nft_gen_attributes - nf_tables ruleset generation attributes
  *

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 8514cc4b22a8123a110ffa907d56483634bcf317..8c067e6663a14adf43212eda165c33240bb87985 100644 (file)
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -577,6 +577,12 @@ config NFT_DUP_NETDEV
        help
          This option enables packet duplication for the "netdev" family.
 
+config NFT_FWD_NETDEV
+       tristate "Netfilter nf_tables netdev packet forwarding support"
+       select NF_DUP_NETDEV
+       help
+         This option enables packet forwarding for the "netdev" family.
+
 endif # NF_TABLES_NETDEV
 
 endif # NF_TABLES

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 5c991335953743c8a76d39322c6e0b73d9a4dcfc..69134541d65bc3e8e2a8d02df39112222b225b7c 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_NFT_REDIR)               += nft_redir.o
 
 # nf_tables netdev
 obj-$(CONFIG_NFT_DUP_NETDEV)   += nft_dup_netdev.o
+obj-$(CONFIG_NFT_FWD_NETDEV)   += nft_fwd_netdev.o
 
 # generic X tables 
 obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o

diff --git a/net/netfilter/nft_fwd_netdev.c b/net/netfilter/nft_fwd_netdev.c
new file mode 100644 (file)
index 0000000..763ebc3
--- /dev/null
+++ b/net/netfilter/nft_fwd_netdev.c
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_dup_netdev.h>
+
+struct nft_fwd_netdev {
+       enum nft_registers      sreg_dev:8;
+};
+
+static void nft_fwd_netdev_eval(const struct nft_expr *expr,
+                               struct nft_regs *regs,
+                               const struct nft_pktinfo *pkt)
+{
+       struct nft_fwd_netdev *priv = nft_expr_priv(expr);
+       int oif = regs->data[priv->sreg_dev];
+
+       nf_dup_netdev_egress(pkt, oif);
+       regs->verdict.code = NF_DROP;
+}
+
+static const struct nla_policy nft_fwd_netdev_policy[NFTA_FWD_MAX + 1] = {
+       [NFTA_FWD_SREG_DEV]     = { .type = NLA_U32 },
+};
+
+static int nft_fwd_netdev_init(const struct nft_ctx *ctx,
+                              const struct nft_expr *expr,
+                              const struct nlattr * const tb[])
+{
+       struct nft_fwd_netdev *priv = nft_expr_priv(expr);
+
+       if (tb[NFTA_FWD_SREG_DEV] == NULL)
+               return -EINVAL;
+
+       priv->sreg_dev = nft_parse_register(tb[NFTA_FWD_SREG_DEV]);
+       return nft_validate_register_load(priv->sreg_dev, sizeof(int));
+}
+
+static const struct nft_expr_ops nft_fwd_netdev_ingress_ops;
+
+static int nft_fwd_netdev_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       struct nft_fwd_netdev *priv = nft_expr_priv(expr);
+
+       if (nft_dump_register(skb, NFTA_FWD_SREG_DEV, priv->sreg_dev))
+               goto nla_put_failure;
+
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static struct nft_expr_type nft_fwd_netdev_type;
+static const struct nft_expr_ops nft_fwd_netdev_ops = {
+       .type           = &nft_fwd_netdev_type,
+       .size           = NFT_EXPR_SIZE(sizeof(struct nft_fwd_netdev)),
+       .eval           = nft_fwd_netdev_eval,
+       .init           = nft_fwd_netdev_init,
+       .dump           = nft_fwd_netdev_dump,
+};
+
+static struct nft_expr_type nft_fwd_netdev_type __read_mostly = {
+       .family         = NFPROTO_NETDEV,
+       .name           = "fwd",
+       .ops            = &nft_fwd_netdev_ops,
+       .policy         = nft_fwd_netdev_policy,
+       .maxattr        = NFTA_FWD_MAX,
+       .owner          = THIS_MODULE,
+};
+
+static int __init nft_fwd_netdev_module_init(void)
+{
+       return nft_register_expr(&nft_fwd_netdev_type);
+}
+
+static void __exit nft_fwd_netdev_module_exit(void)
+{
+       nft_unregister_expr(&nft_fwd_netdev_type);
+}
+
+module_init(nft_fwd_netdev_module_init);
+module_exit(nft_fwd_netdev_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_AF_EXPR(5, "fwd");