netfilter: nf_tables: Add meta expression key for bridge interface name

NFT_META_BRI_IIFNAME to get packet input bridge interface name
NFT_META_BRI_OIFNAME to get packet output bridge interface name

Such meta key are accessible only through NFPROTO_BRIDGE family, on a
dedicated nft meta module: nft_meta_bridge.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 154 insertions, 2 deletions

diff --git a/net/bridge/Makefile b/net/bridge/Makefile
index e85498b2f166..906a18b4e74a 100644
--- a/net/bridge/Makefile
+++ b/net/bridge/Makefile
@@ -16,4 +16,4 @@ bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o
 
 bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o
 
-obj-$(CONFIG_BRIDGE_NF_EBTABLES) += netfilter/
+obj-$(CONFIG_BRIDGE_NETFILTER) += netfilter/
diff --git a/net/bridge/netfilter/Kconfig b/net/bridge/netfilter/Kconfig
index 5ca74a0e595f..3baf29d34e62 100644
--- a/net/bridge/netfilter/Kconfig
+++ b/net/bridge/netfilter/Kconfig
@@ -2,13 +2,25 @@
 # Bridge netfilter configuration
 #
 #
-config NF_TABLES_BRIDGE
+menuconfig NF_TABLES_BRIDGE
         depends on NF_TABLES
+        select BRIDGE_NETFILTER
         tristate "Ethernet Bridge nf_tables support"
 
+if NF_TABLES_BRIDGE
+
+config NFT_BRIDGE_META
+        tristate "Netfilter nf_table bridge meta support"
+        depends on NFT_META
+        help
+          Add support for bridge dedicated meta key.
+
+endif # NF_TABLES_BRIDGE
+
 menuconfig BRIDGE_NF_EBTABLES
         tristate "Ethernet Bridge tables (ebtables) support"
         depends on BRIDGE && NETFILTER
+        select BRIDGE_NETFILTER
         select NETFILTER_XTABLES
         help
           ebtables is a general, extensible frame/packet identification
diff --git a/net/bridge/netfilter/Makefile b/net/bridge/netfilter/Makefile
index ea7629f58b3d..6f2f3943d66f 100644
--- a/net/bridge/netfilter/Makefile
+++ b/net/bridge/netfilter/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_NF_TABLES_BRIDGE) += nf_tables_bridge.o
+obj-$(CONFIG_NFT_BRIDGE_META)  += nft_meta_bridge.o
 
 obj-$(CONFIG_BRIDGE_NF_EBTABLES) += ebtables.o
 
diff --git a/net/bridge/netfilter/nft_meta_bridge.c b/net/bridge/netfilter/nft_meta_bridge.c
new file mode 100644
index 000000000000..4f02109d708f
--- /dev/null
+++ b/net/bridge/netfilter/nft_meta_bridge.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * 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/nft_meta.h>
+
+#include "../br_private.h"
+
+static void nft_meta_bridge_get_eval(const struct nft_expr *expr,
+                                     struct nft_data data[NFT_REG_MAX + 1],
+                                     const struct nft_pktinfo *pkt)
+{
+        const struct nft_meta *priv = nft_expr_priv(expr);
+        const struct net_device *in = pkt->in, *out = pkt->out;
+        struct nft_data *dest = &data[priv->dreg];
+        const struct net_bridge_port *p;
+
+        switch (priv->key) {
+        case NFT_META_BRI_IIFNAME:
+                if (in == NULL || (p = br_port_get_rcu(in)) == NULL)
+                        goto err;
+                break;
+        case NFT_META_BRI_OIFNAME:
+                if (out == NULL || (p = br_port_get_rcu(out)) == NULL)
+                        goto err;
+                break;
+        default:
+                goto out;
+        }
+
+        strncpy((char *)dest->data, p->br->dev->name, sizeof(dest->data));
+        return;
+out:
+        return nft_meta_get_eval(expr, data, pkt);
+err:
+        data[NFT_REG_VERDICT].verdict = NFT_BREAK;
+}
+
+static int nft_meta_bridge_get_init(const struct nft_ctx *ctx,
+                                    const struct nft_expr *expr,
+                                    const struct nlattr * const tb[])
+{
+        struct nft_meta *priv = nft_expr_priv(expr);
+        int err;
+
+        priv->key = ntohl(nla_get_be32(tb[NFTA_META_KEY]));
+        switch (priv->key) {
+        case NFT_META_BRI_IIFNAME:
+        case NFT_META_BRI_OIFNAME:
+                break;
+        default:
+                return nft_meta_get_init(ctx, expr, tb);
+        }
+
+        priv->dreg = ntohl(nla_get_be32(tb[NFTA_META_DREG]));
+        err = nft_validate_output_register(priv->dreg);
+        if (err < 0)
+                return err;
+
+        err = nft_validate_data_load(ctx, priv->dreg, NULL, NFT_DATA_VALUE);
+        if (err < 0)
+                return err;
+
+        return 0;
+}
+
+static struct nft_expr_type nft_meta_bridge_type;
+static const struct nft_expr_ops nft_meta_bridge_get_ops = {
+        .type           = &nft_meta_bridge_type,
+        .size           = NFT_EXPR_SIZE(sizeof(struct nft_meta)),
+        .eval           = nft_meta_bridge_get_eval,
+        .init           = nft_meta_bridge_get_init,
+        .dump           = nft_meta_get_dump,
+};
+
+static const struct nft_expr_ops nft_meta_bridge_set_ops = {
+        .type           = &nft_meta_bridge_type,
+        .size           = NFT_EXPR_SIZE(sizeof(struct nft_meta)),
+        .eval           = nft_meta_set_eval,
+        .init           = nft_meta_set_init,
+        .dump           = nft_meta_set_dump,
+};
+
+static const struct nft_expr_ops *
+nft_meta_bridge_select_ops(const struct nft_ctx *ctx,
+                           const struct nlattr * const tb[])
+{
+        if (tb[NFTA_META_KEY] == NULL)
+                return ERR_PTR(-EINVAL);
+
+        if (tb[NFTA_META_DREG] && tb[NFTA_META_SREG])
+                return ERR_PTR(-EINVAL);
+
+        if (tb[NFTA_META_DREG])
+                return &nft_meta_bridge_get_ops;
+
+        if (tb[NFTA_META_SREG])
+                return &nft_meta_bridge_set_ops;
+
+        return ERR_PTR(-EINVAL);
+}
+
+static struct nft_expr_type nft_meta_bridge_type __read_mostly = {
+        .family         = NFPROTO_BRIDGE,
+        .name           = "meta",
+        .select_ops     = &nft_meta_bridge_select_ops,
+        .policy         = nft_meta_policy,
+        .maxattr        = NFTA_META_MAX,
+        .owner          = THIS_MODULE,
+};
+
+static int __init nft_meta_bridge_module_init(void)
+{
+        return nft_register_expr(&nft_meta_bridge_type);
+}
+
+static void __exit nft_meta_bridge_module_exit(void)
+{
+        nft_unregister_expr(&nft_meta_bridge_type);
+}
+
+module_init(nft_meta_bridge_module_init);
+module_exit(nft_meta_bridge_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
+MODULE_ALIAS_NFT_AF_EXPR(AF_BRIDGE, "meta");