netfilter: nf_tables: add support for native socket matching

Now it can only match the transparent flag of an ip/ipv6 socket.

Signed-off-by: Máté Eckl <ecklm94@gmail.com>
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 9c71f02..3d46c82 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -905,6 +905,31 @@ enum nft_rt_attributes {
 #define NFTA_RT_MAX            (__NFTA_RT_MAX - 1)
 
 /**
+ * enum nft_socket_attributes - nf_tables socket expression netlink attributes
+ *
+ * @NFTA_SOCKET_KEY: socket key to match
+ * @NFTA_SOCKET_DREG: destination register
+ */
+enum nft_socket_attributes {
+       NFTA_SOCKET_UNSPEC,
+       NFTA_SOCKET_KEY,
+       NFTA_SOCKET_DREG,
+       __NFTA_SOCKET_MAX
+};
+#define NFTA_SOCKET_MAX                (__NFTA_SOCKET_MAX - 1)
+
+/*
+ * enum nft_socket_keys - nf_tables socket expression keys
+ *
+ * @NFT_SOCKET_TRANSPARENT: Value of the IP(V6)_TRANSPARENT socket option_
+ */
+enum nft_socket_keys {
+       NFT_SOCKET_TRANSPARENT,
+       __NFT_SOCKET_MAX
+};
+#define NFT_SOCKET_MAX (__NFT_SOCKET_MAX - 1)
+
+/**
  * enum nft_ct_keys - nf_tables ct expression keys
  *
  * @NFT_CT_STATE: conntrack state (bitmask of enum ip_conntrack_info)

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 3ec8886..276e1e3 100644 (file)
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -613,6 +613,15 @@ config NFT_FIB_INET
          The lookup will be delegated to the IPv4 or IPv6 FIB depending
          on the protocol of the packet.
 
+config NFT_SOCKET
+       tristate "Netfilter nf_tables socket match support"
+       depends on IPV6 || IPV6=n
+       select NF_SOCKET_IPV4
+       select NF_SOCKET_IPV6 if IPV6
+       help
+         This option allows matching for the presence or absence of a
+         corresponding socket and its attributes.
+
 if NF_TABLES_NETDEV
 
 config NF_DUP_NETDEV

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 9b34343..eec1695 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -102,6 +102,7 @@ obj-$(CONFIG_NFT_FIB)               += nft_fib.o
 obj-$(CONFIG_NFT_FIB_INET)     += nft_fib_inet.o
 obj-$(CONFIG_NFT_FIB_NETDEV)   += nft_fib_netdev.o
 obj-$(CONFIG_NF_OSF)           += nf_osf.o
+obj-$(CONFIG_NFT_SOCKET)       += nft_socket.o
 
 # nf_tables netdev
 obj-$(CONFIG_NFT_DUP_NETDEV)   += nft_dup_netdev.o

diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c
new file mode 100644 (file)
index 0000000..d863370
--- /dev/null
+++ b/net/netfilter/nft_socket.c
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/module.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+#include <net/netfilter/nf_socket.h>
+#include <net/inet_sock.h>
+
+struct nft_socket {
+       enum nft_socket_keys            key:8;
+       union {
+               enum nft_registers      dreg:8;
+       };
+};
+
+static void nft_socket_eval(const struct nft_expr *expr,
+                           struct nft_regs *regs,
+                           const struct nft_pktinfo *pkt)
+{
+       const struct nft_socket *priv = nft_expr_priv(expr);
+       struct sk_buff *skb = pkt->skb;
+       struct sock *sk = skb->sk;
+       u32 *dest = &regs->data[priv->dreg];
+
+       if (!sk)
+               switch(nft_pf(pkt)) {
+               case NFPROTO_IPV4:
+                       sk = nf_sk_lookup_slow_v4(nft_net(pkt), skb, nft_in(pkt));
+                       break;
+#if IS_ENABLED(CONFIG_NF_SOCKET_IPV6)
+               case NFPROTO_IPV6:
+                       sk = nf_sk_lookup_slow_v6(nft_net(pkt), skb, nft_in(pkt));
+                       break;
+#endif
+               default:
+                       WARN_ON_ONCE(1);
+                       regs->verdict.code = NFT_BREAK;
+                       return;
+               }
+
+       if(!sk) {
+               nft_reg_store8(dest, 0);
+               return;
+       }
+
+       /* So that subsequent socket matching not to require other lookups. */
+       skb->sk = sk;
+
+       switch(priv->key) {
+       case NFT_SOCKET_TRANSPARENT:
+               nft_reg_store8(dest, nf_sk_is_transparent(sk));
+               break;
+       default:
+               WARN_ON(1);
+               regs->verdict.code = NFT_BREAK;
+       }
+}
+
+static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
+       [NFTA_SOCKET_KEY]               = { .type = NLA_U32 },
+       [NFTA_SOCKET_DREG]              = { .type = NLA_U32 },
+};
+
+static int nft_socket_init(const struct nft_ctx *ctx,
+                          const struct nft_expr *expr,
+                          const struct nlattr * const tb[])
+{
+       struct nft_socket *priv = nft_expr_priv(expr);
+       unsigned int len;
+
+       if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])
+               return -EINVAL;
+
+       switch(ctx->family) {
+       case NFPROTO_IPV4:
+#if IS_ENABLED(CONFIG_NF_SOCKET_IPV6)
+       case NFPROTO_IPV6:
+#endif
+       case NFPROTO_INET:
+               break;
+       default:
+               return -EOPNOTSUPP;
+       }
+
+       priv->key = ntohl(nla_get_u32(tb[NFTA_SOCKET_KEY]));
+       switch(priv->key) {
+       case NFT_SOCKET_TRANSPARENT:
+               len = sizeof(u8);
+               break;
+       default:
+               return -EOPNOTSUPP;
+       }
+
+       priv->dreg = nft_parse_register(tb[NFTA_SOCKET_DREG]);
+       return nft_validate_register_store(ctx, priv->dreg, NULL,
+                                          NFT_DATA_VALUE, len);
+}
+
+static int nft_socket_dump(struct sk_buff *skb,
+                          const struct nft_expr *expr)
+{
+       const struct nft_socket *priv = nft_expr_priv(expr);
+
+       if (nla_put_u32(skb, NFTA_SOCKET_KEY, htonl(priv->key)))
+               return -1;
+       if (nft_dump_register(skb, NFTA_SOCKET_DREG, priv->dreg))
+               return -1;
+       return 0;
+}
+
+static struct nft_expr_type nft_socket_type;
+static const struct nft_expr_ops nft_socket_ops = {
+       .type           = &nft_socket_type,
+       .size           = NFT_EXPR_SIZE(sizeof(struct nft_socket)),
+       .eval           = nft_socket_eval,
+       .init           = nft_socket_init,
+       .dump           = nft_socket_dump,
+};
+
+static struct nft_expr_type nft_socket_type __read_mostly = {
+       .name           = "socket",
+       .ops            = &nft_socket_ops,
+       .policy         = nft_socket_policy,
+       .maxattr        = NFTA_SOCKET_MAX,
+       .owner          = THIS_MODULE,
+};
+
+static int __init nft_socket_module_init(void)
+{
+       return nft_register_expr(&nft_socket_type);
+}
+
+static void __exit nft_socket_module_exit(void)
+{
+       nft_unregister_expr(&nft_socket_type);
+}
+
+module_init(nft_socket_module_init);
+module_exit(nft_socket_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Máté Eckl");
+MODULE_DESCRIPTION("nf_tables socket match module");