This new expression allows us to refer to existing stateful objects from
rules.
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
v2:
* Rename:
NFTA_OBJREF_TYPE -> NFTA_OBJREF_IMM_TYPE
NFTA_OBJREF_NAME -> NFTA_OBJREF_IMM_NAME
so both refer to data that is pass as attribute, ie. not coming from any
register.
include/uapi/linux/netfilter/nf_tables.h | 14 ++++
net/netfilter/Kconfig | 6 ++
net/netfilter/Makefile | 1 +
net/netfilter/nft_objref.c | 112 +++++++++++++++++++++++++++++++
4 files changed, 133 insertions(+)
create mode 100644 net/netfilter/nft_objref.c
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index b73afab4ad8f..e95d5f4f136b 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -1132,6 +1132,20 @@ 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
*
* @NFTA_GEN_ID: Ruleset generation ID (NLA_U32)
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 44410d30d461..44ead64b35da 100644
--- 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 5bbf767672ec..8dbc518324fd 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -89,6 +89,7 @@ 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
index 000000000000..23820f796aad
--- /dev/null
+++ b/net/netfilter/nft_objref.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2012-2016 Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
+ *
+ * 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@xxxxxxxxxxxxx>");
+MODULE_ALIAS_NFT_EXPR("objref");
--
2.1.4
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