Re: [PATCH v4] netfilter: nf_tables: add hash expression

2016-08-11 Thread Pablo Neira Ayuso 
On Thu, Aug 11, 2016 at 09:23:14AM +0200, Laura Garcia Liebana wrote:
> diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
> new file mode 100644
> index 000..eb05527
> --- /dev/null
> +++ b/net/netfilter/nft_hash.c
> @@ -0,0 +1,136 @@
> +/*
> + * Copyright (c) 2016 Laura Garcia 
> + *
> + * 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 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +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 = >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) &&

>From sreg, we load, good.

> +nft_validate_register_load(priv->dreg, sizeof(u32));

But to dreg we store. This should validate a store.
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH v4] netfilter: nf_tables: add hash expression

2016-08-11 Thread Laura Garcia Liebana 
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 
---
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

 include/uapi/linux/netfilter/nf_tables.h |  20 +
 net/netfilter/Kconfig|   6 ++
 net/netfilter/Makefile   |   1 +
 net/netfilter/nft_hash.c | 136 +++
 4 files changed, 163 insertions(+)
 create mode 100644 net/netfilter/nft_hash.c

diff --git a/include/uapi/linux/netfilter/nf_tables.h 
b/include/uapi/linux/netfilter/nf_tables.h
index 0e7928e..1399946 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -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)
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index a2e4cf6..1074700 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -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
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 441a3c0..faa277e 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -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
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
new file mode 100644
index 000..eb05527
--- /dev/null
+++ b/net/netfilter/nft_hash.c
@@ -0,0 +1,136 @@
+/*
+ * Copyright (c) 2016 Laura Garcia 
+ *
+ * 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 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+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 = >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 ==