@@ -724,6 +724,26 @@ enum nft_meta_keys {
};
/**
+ * enum nft_hash_attributes - nf_tables hash expression netlink attributes
+ *
+ * @NFTA_HASH_SREG: source register (NLA_U32)
+ * @NFTA_HASH_DREG: destination register (NLA_U32)
+ * @NFTA_HASH_LEN: source data length (NLA_U32)
+ * @NFTA_HASH_MODULUS: modulus value (NLA_U32)
+ * @NFTA_HASH_SEED: seed value (NLA_U32)
+ */
+enum nft_hash_attributes {
+ NFTA_HASH_UNSPEC,
+ NFTA_HASH_SREG,
+ NFTA_HASH_DREG,
+ NFTA_HASH_LEN,
+ NFTA_HASH_MODULUS,
+ NFTA_HASH_SEED,
+ __NFTA_HASH_MAX,
+};
+#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1)
+
+/**
* enum nft_meta_attributes - nf_tables meta expression netlink attributes
*
* @NFTA_META_DREG: destination register (NLA_U32)
@@ -569,6 +569,12 @@ config NFT_COMPAT
x_tables match/target extensions over the nf_tables
framework.
+config NFT_HASH
+ tristate "Netfilter nf_tables hash module"
+ help
+ This option adds the "hash" expression that you can use to perform
+ a hash operation on registers.
+
if NF_TABLES_NETDEV
config NF_DUP_NETDEV
@@ -93,6 +93,7 @@ obj-$(CONFIG_NFT_COUNTER) += nft_counter.o
obj-$(CONFIG_NFT_LOG) += nft_log.o
obj-$(CONFIG_NFT_MASQ) += nft_masq.o
obj-$(CONFIG_NFT_REDIR) += nft_redir.o
+obj-$(CONFIG_NFT_HASH) += nft_hash.o
# nf_tables netdev
obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o
new file mode 100644
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2016 Laura Garcia <nevola@gmail.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 <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+#include <linux/jhash.h>
+
+struct nft_hash {
+ enum nft_registers sreg:8;
+ enum nft_registers dreg:8;
+ u8 len;
+ u32 modulus;
+ u32 seed;
+};
+
+static void nft_hash_eval(const struct nft_expr *expr,
+ struct nft_regs *regs,
+ const struct nft_pktinfo *pkt)
+{
+ struct nft_hash *priv = nft_expr_priv(expr);
+ const void *data = ®s->data[priv->sreg];
+ u32 h;
+
+ h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
+
+ regs->data[priv->dreg] = h;
+}
+
+const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
+ [NFTA_HASH_SREG] = { .type = NLA_U32 },
+ [NFTA_HASH_DREG] = { .type = NLA_U32 },
+ [NFTA_HASH_LEN] = { .type = NLA_U32 },
+ [NFTA_HASH_MODULUS] = { .type = NLA_U32 },
+ [NFTA_HASH_SEED] = { .type = NLA_U32 },
+};
+
+static int nft_hash_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_hash *priv = nft_expr_priv(expr);
+ u32 len;
+
+ if (!tb[NFTA_HASH_SREG] ||
+ !tb[NFTA_HASH_DREG] ||
+ !tb[NFTA_HASH_LEN] ||
+ !tb[NFTA_HASH_SEED] ||
+ !tb[NFTA_HASH_MODULUS])
+ return -EINVAL;
+
+ priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
+ priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
+
+ len = ntohl(nla_get_be32(tb[NFTA_HASH_LEN]));
+ if (len == 0 || len > U8_MAX)
+ return -ERANGE;
+
+ priv->len = len;
+
+ priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS]));
+ if (priv->modulus <= 1)
+ return -ERANGE;
+
+ priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
+
+ return nft_validate_register_load(priv->sreg, len) &&
+ nft_validate_register_store(ctx, priv->dreg, NULL,
+ NFT_DATA_VALUE, sizeof(u32));
+}
+
+static int nft_hash_dump(struct sk_buff *skb,
+ const struct nft_expr *expr)
+{
+ const struct nft_hash *priv = nft_expr_priv(expr);
+
+ if (nft_dump_register(skb, NFTA_HASH_SREG, priv->sreg))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_HASH_LEN, priv->len))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_HASH_MODULUS, priv->modulus))
+ goto nla_put_failure;
+ if (nft_dump_register(skb, NFTA_HASH_SEED, priv->seed))
+ goto nla_put_failure;
+
+ return 0;
+
+nla_put_failure:
+ return -1;
+}
+
+static struct nft_expr_type nft_hash_type;
+static const struct nft_expr_ops nft_hash_ops = {
+ .type = &nft_hash_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_hash)),
+ .eval = nft_hash_eval,
+ .init = nft_hash_init,
+ .dump = nft_hash_dump,
+};
+
+static struct nft_expr_type nft_hash_type __read_mostly = {
+ .name = "hash",
+ .ops = &nft_hash_ops,
+ .policy = nft_hash_policy,
+ .maxattr = NFTA_HASH_MAX,
+ .owner = THIS_MODULE,
+};
+
+static int __init nft_hash_module_init(void)
+{
+ return nft_register_expr(&nft_hash_type);
+}
+
+static void __exit nft_hash_module_exit(void)
+{
+ nft_unregister_expr(&nft_hash_type);
+}
+
+module_init(nft_hash_module_init);
+module_exit(nft_hash_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Laura Garcia <nevola@gmail.com>");
+MODULE_ALIAS_NFT_EXPR("hash");
This patch adds a new hash expression, this provides jhash support but this can be extended to support for other hash functions. The modulus and seed already comes embedded into this new expression. Use case example: meta mark set hash ip saddr mod 10 Signed-off-by: Laura Garcia Liebana <nevola@gmail.com> --- Changes in V2: - Define len as u8 instead of u32 - Improved module description - Remove unnecessary includes Changes in V3: - Add null checks in init() - Include registers load validation Changes in V4: - Use ERANGE in some cases according to the lib/nlattr.c policy - Typo fixed - Use nft_validate_register_load instead of nft_validate_register_store Changes in V5: - Use nft_validate_register_store for dreg in init() include/uapi/linux/netfilter/nf_tables.h | 20 +++++ net/netfilter/Kconfig | 6 ++ net/netfilter/Makefile | 1 + net/netfilter/nft_hash.c | 137 +++++++++++++++++++++++++++++++ 4 files changed, 164 insertions(+) create mode 100644 net/netfilter/nft_hash.c