netfilter: nf_tables: add stateful object reference expression

This new expression allows us to refer to existing stateful objects from
rules.

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 ad0577ba5d2a48f2641a0a3e05e27bb370ac8d64..1043ce4250c545a42fb80629cfa27b31ef35df47 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -1137,6 +1137,20 @@ enum nft_fwd_attributes {
 };
 #define NFTA_FWD_MAX   (__NFTA_FWD_MAX - 1)
 
+/**
+ * enum nft_objref_attributes - nf_tables stateful object expression netlink attributes
+ *
+ * @NFTA_OBJREF_IMM_TYPE: object type for immediate reference (NLA_U32: nft_register)
+ * @NFTA_OBJREF_IMM_NAME: object name for immediate reference (NLA_STRING)
+ */
+enum nft_objref_attributes {
+       NFTA_OBJREF_UNSPEC,
+       NFTA_OBJREF_IMM_TYPE,
+       NFTA_OBJREF_IMM_NAME,
+       __NFTA_OBJREF_MAX
+};
+#define NFTA_OBJREF_MAX        (__NFTA_OBJREF_MAX - 1)
+
 /**
  * enum nft_gen_attributes - nf_tables ruleset generation attributes
  *

diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index def4be06cda6ef54ee3ac67adc46101cf4054501..63729b489c2c17608575e4f58adb0c264e182d0b 100644 (file)
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -551,6 +551,12 @@ config NFT_NAT
          This option adds the "nat" expression that you can use to perform
          typical Network Address Translation (NAT) packet transformations.
 
+config NFT_OBJREF
+       tristate "Netfilter nf_tables stateful object reference module"
+       help
+         This option adds the "objref" expression that allows you to refer to
+         stateful objects, such as counters and quotas.
+
 config NFT_QUEUE
        depends on NETFILTER_NETLINK_QUEUE
        tristate "Netfilter nf_tables queue module"

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index e4c8c1d7aaed703c512852b1a281d07879974bd3..ca30d1960f1db95964f06c5d23a08a1b83e492af 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_NFT_NUMGEN)      += nft_numgen.o
 obj-$(CONFIG_NFT_CT)           += nft_ct.o
 obj-$(CONFIG_NFT_LIMIT)                += nft_limit.o
 obj-$(CONFIG_NFT_NAT)          += nft_nat.o
+obj-$(CONFIG_NFT_OBJREF)       += nft_objref.o
 obj-$(CONFIG_NFT_QUEUE)                += nft_queue.o
 obj-$(CONFIG_NFT_QUOTA)                += nft_quota.o
 obj-$(CONFIG_NFT_REJECT)       += nft_reject.o

diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c
new file mode 100644 (file)
index 0000000..23820f7
--- /dev/null
+++ b/net/netfilter/nft_objref.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2012-2016 Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+
+#define nft_objref_priv(expr)  *((struct nft_object **)nft_expr_priv(expr))
+
+static void nft_objref_eval(const struct nft_expr *expr,
+                           struct nft_regs *regs,
+                           const struct nft_pktinfo *pkt)
+{
+       struct nft_object *obj = nft_objref_priv(expr);
+
+       obj->type->eval(obj, regs, pkt);
+}
+
+static int nft_objref_init(const struct nft_ctx *ctx,
+                          const struct nft_expr *expr,
+                          const struct nlattr * const tb[])
+{
+       struct nft_object *obj = nft_objref_priv(expr);
+       u8 genmask = nft_genmask_next(ctx->net);
+       u32 objtype;
+
+       if (!tb[NFTA_OBJREF_IMM_NAME] ||
+           !tb[NFTA_OBJREF_IMM_TYPE])
+               return -EINVAL;
+
+       objtype = ntohl(nla_get_be32(tb[NFTA_OBJREF_IMM_TYPE]));
+       obj = nf_tables_obj_lookup(ctx->table, tb[NFTA_OBJREF_IMM_NAME], objtype,
+                                  genmask);
+       if (IS_ERR(obj))
+               return -ENOENT;
+
+       nft_objref_priv(expr) = obj;
+       obj->use++;
+
+       return 0;
+}
+
+static int nft_objref_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       const struct nft_object *obj = nft_objref_priv(expr);
+
+       if (nla_put_string(skb, NFTA_OBJREF_IMM_NAME, obj->name) ||
+           nla_put_be32(skb, NFTA_OBJREF_IMM_TYPE, htonl(obj->type->type)))
+               goto nla_put_failure;
+
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static void nft_objref_destroy(const struct nft_ctx *ctx,
+                              const struct nft_expr *expr)
+{
+       struct nft_object *obj = nft_objref_priv(expr);
+
+       obj->use--;
+}
+
+static struct nft_expr_type nft_objref_type;
+static const struct nft_expr_ops nft_objref_ops = {
+       .type           = &nft_objref_type,
+       .size           = NFT_EXPR_SIZE(sizeof(struct nft_object *)),
+       .eval           = nft_objref_eval,
+       .init           = nft_objref_init,
+       .destroy        = nft_objref_destroy,
+       .dump           = nft_objref_dump,
+};
+
+static const struct nla_policy nft_objref_policy[NFTA_OBJREF_MAX + 1] = {
+       [NFTA_OBJREF_IMM_NAME]  = { .type = NLA_STRING },
+       [NFTA_OBJREF_IMM_TYPE]  = { .type = NLA_U32 },
+};
+
+static struct nft_expr_type nft_objref_type __read_mostly = {
+       .name           = "objref",
+       .ops            = &nft_objref_ops,
+       .policy         = nft_objref_policy,
+       .maxattr        = NFTA_OBJREF_MAX,
+       .owner          = THIS_MODULE,
+};
+
+static int __init nft_objref_module_init(void)
+{
+       return nft_register_expr(&nft_objref_type);
+}
+
+static void __exit nft_objref_module_exit(void)
+{
+       nft_unregister_expr(&nft_objref_type);
+}
+
+module_init(nft_objref_module_init);
+module_exit(nft_objref_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
+MODULE_ALIAS_NFT_EXPR("objref");