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Message-Id: <1473073124-5015-13-git-send-email-pablo@netfilter.org>
Date: Mon, 5 Sep 2016 12:58:27 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH 12/29] netfilter: nf_tables: add number generator expression
From: Laura Garcia Liebana <nevola@...il.com>
This patch adds the numgen expression that allows us to generated
incremental and random numbers, this generator is bound to a upper limit
that is specified by userspace.
This expression is useful to distribute packets in a round-robin fashion
as well as randomly.
Signed-off-by: Laura Garcia Liebana <nevola@...il.com>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
include/uapi/linux/netfilter/nf_tables.h | 24 ++++
net/netfilter/Kconfig | 6 +
net/netfilter/Makefile | 1 +
net/netfilter/nft_numgen.c | 192 +++++++++++++++++++++++++++++++
4 files changed, 223 insertions(+)
create mode 100644 net/netfilter/nft_numgen.c
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 784fbf1..8c9d6ff 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -1121,4 +1121,28 @@ enum nft_trace_types {
__NFT_TRACETYPE_MAX
};
#define NFT_TRACETYPE_MAX (__NFT_TRACETYPE_MAX - 1)
+
+/**
+ * enum nft_ng_attributes - nf_tables number generator expression netlink attributes
+ *
+ * @NFTA_NG_DREG: destination register (NLA_U32)
+ * @NFTA_NG_UNTIL: source value to increment the counter until reset (NLA_U32)
+ * @NFTA_NG_TYPE: operation type (NLA_U32)
+ */
+enum nft_ng_attributes {
+ NFTA_NG_UNSPEC,
+ NFTA_NG_DREG,
+ NFTA_NG_UNTIL,
+ NFTA_NG_TYPE,
+ __NFTA_NG_MAX
+};
+#define NFTA_NG_MAX (__NFTA_NG_MAX - 1)
+
+enum nft_ng_types {
+ NFT_NG_INCREMENTAL,
+ NFT_NG_RANDOM,
+ __NFT_NG_MAX
+};
+#define NFT_NG_MAX (__NFT_NG_MAX - 1)
+
#endif /* _LINUX_NF_TABLES_H */
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 29a8078..e8d56d9 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -474,6 +474,12 @@ config NFT_META
This option adds the "meta" expression that you can use to match and
to set packet metainformation such as the packet mark.
+config NFT_NUMGEN
+ tristate "Netfilter nf_tables number generator module"
+ help
+ This option adds the number generator expression used to perform
+ incremental counting and random numbers bound to a upper limit.
+
config NFT_CT
depends on NF_CONNTRACK
tristate "Netfilter nf_tables conntrack module"
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0fc42df..0c858110 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_NF_TABLES_NETDEV) += nf_tables_netdev.o
obj-$(CONFIG_NFT_COMPAT) += nft_compat.o
obj-$(CONFIG_NFT_EXTHDR) += nft_exthdr.o
obj-$(CONFIG_NFT_META) += nft_meta.o
+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
diff --git a/net/netfilter/nft_numgen.c b/net/netfilter/nft_numgen.c
new file mode 100644
index 0000000..176e26d
--- /dev/null
+++ b/net/netfilter/nft_numgen.c
@@ -0,0 +1,192 @@
+/*
+ * Copyright (c) 2016 Laura Garcia <nevola@...il.com>
+ *
+ * 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 <linux/static_key.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+
+static DEFINE_PER_CPU(struct rnd_state, nft_numgen_prandom_state);
+
+struct nft_ng_inc {
+ enum nft_registers dreg:8;
+ u32 until;
+ atomic_t counter;
+};
+
+static void nft_ng_inc_eval(const struct nft_expr *expr,
+ struct nft_regs *regs,
+ const struct nft_pktinfo *pkt)
+{
+ struct nft_ng_inc *priv = nft_expr_priv(expr);
+ u32 nval, oval;
+
+ do {
+ oval = atomic_read(&priv->counter);
+ nval = (oval + 1 < priv->until) ? oval + 1 : 0;
+ } while (atomic_cmpxchg(&priv->counter, oval, nval) != oval);
+
+ memcpy(®s->data[priv->dreg], &priv->counter, sizeof(u32));
+}
+
+static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {
+ [NFTA_NG_DREG] = { .type = NLA_U32 },
+ [NFTA_NG_UNTIL] = { .type = NLA_U32 },
+ [NFTA_NG_TYPE] = { .type = NLA_U32 },
+};
+
+static int nft_ng_inc_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_ng_inc *priv = nft_expr_priv(expr);
+
+ priv->until = ntohl(nla_get_be32(tb[NFTA_NG_UNTIL]));
+ if (priv->until == 0)
+ return -ERANGE;
+
+ priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);
+ atomic_set(&priv->counter, 0);
+
+ return nft_validate_register_store(ctx, priv->dreg, NULL,
+ NFT_DATA_VALUE, sizeof(u32));
+}
+
+static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,
+ u32 until, enum nft_ng_types type)
+{
+ if (nft_dump_register(skb, NFTA_NG_DREG, dreg))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_NG_UNTIL, until))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_NG_TYPE, type))
+ goto nla_put_failure;
+
+ return 0;
+
+nla_put_failure:
+ return -1;
+}
+
+static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+ const struct nft_ng_inc *priv = nft_expr_priv(expr);
+
+ return nft_ng_dump(skb, priv->dreg, priv->until, NFT_NG_INCREMENTAL);
+}
+
+struct nft_ng_random {
+ enum nft_registers dreg:8;
+ u32 until;
+};
+
+static void nft_ng_random_eval(const struct nft_expr *expr,
+ struct nft_regs *regs,
+ const struct nft_pktinfo *pkt)
+{
+ struct nft_ng_random *priv = nft_expr_priv(expr);
+ struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);
+
+ regs->data[priv->dreg] = reciprocal_scale(prandom_u32_state(state),
+ priv->until);
+}
+
+static int nft_ng_random_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_ng_random *priv = nft_expr_priv(expr);
+
+ priv->until = ntohl(nla_get_be32(tb[NFTA_NG_UNTIL]));
+ if (priv->until == 0)
+ return -ERANGE;
+
+ prandom_init_once(&nft_numgen_prandom_state);
+
+ priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);
+
+ return nft_validate_register_store(ctx, priv->dreg, NULL,
+ NFT_DATA_VALUE, sizeof(u32));
+}
+
+static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+ const struct nft_ng_random *priv = nft_expr_priv(expr);
+
+ return nft_ng_dump(skb, priv->dreg, priv->until, NFT_NG_RANDOM);
+}
+
+static struct nft_expr_type nft_ng_type;
+static const struct nft_expr_ops nft_ng_inc_ops = {
+ .type = &nft_ng_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_inc)),
+ .eval = nft_ng_inc_eval,
+ .init = nft_ng_inc_init,
+ .dump = nft_ng_inc_dump,
+};
+
+static const struct nft_expr_ops nft_ng_random_ops = {
+ .type = &nft_ng_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_ng_random)),
+ .eval = nft_ng_random_eval,
+ .init = nft_ng_random_init,
+ .dump = nft_ng_random_dump,
+};
+
+static const struct nft_expr_ops *
+nft_ng_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
+{
+ u32 type;
+
+ if (!tb[NFTA_NG_DREG] ||
+ !tb[NFTA_NG_UNTIL] ||
+ !tb[NFTA_NG_TYPE])
+ return ERR_PTR(-EINVAL);
+
+ type = ntohl(nla_get_be32(tb[NFTA_NG_TYPE]));
+
+ switch (type) {
+ case NFT_NG_INCREMENTAL:
+ return &nft_ng_inc_ops;
+ case NFT_NG_RANDOM:
+ return &nft_ng_random_ops;
+ }
+
+ return ERR_PTR(-EINVAL);
+}
+
+static struct nft_expr_type nft_ng_type __read_mostly = {
+ .name = "numgen",
+ .select_ops = &nft_ng_select_ops,
+ .policy = nft_ng_policy,
+ .maxattr = NFTA_NG_MAX,
+ .owner = THIS_MODULE,
+};
+
+static int __init nft_ng_module_init(void)
+{
+ return nft_register_expr(&nft_ng_type);
+}
+
+static void __exit nft_ng_module_exit(void)
+{
+ nft_unregister_expr(&nft_ng_type);
+}
+
+module_init(nft_ng_module_init);
+module_exit(nft_ng_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Laura Garcia <nevola@...il.com>");
+MODULE_ALIAS_NFT_EXPR("numgen");
--
2.1.4
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