Add support to pass through an offset to the hash value. With this
feature, the sysadmin is able to generate a hash with a given
offset value.
Example:
meta mark set jhash ip saddr mod 2 seed 0xabcd sum 100
This option generates marks according to the source address from 100 to
101.
Signed-off-by: Laura Garcia Liebana <[email protected]>
---
include/uapi/linux/netfilter/nf_tables.h | 2 ++
net/netfilter/nft_hash.c | 13 +++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/netfilter/nf_tables.h
b/include/uapi/linux/netfilter/nf_tables.h
index 4dbeeed..8026684 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -764,6 +764,7 @@ enum nft_meta_keys {
* @NFTA_HASH_LEN: source data length (NLA_U32)
* @NFTA_HASH_MODULUS: modulus value (NLA_U32)
* @NFTA_HASH_SEED: seed value (NLA_U32)
+ * @NFTA_HASH_SUM: Hash offset value (NLA_U32)
*/
enum nft_hash_attributes {
NFTA_HASH_UNSPEC,
@@ -772,6 +773,7 @@ enum nft_hash_attributes {
NFTA_HASH_LEN,
NFTA_HASH_MODULUS,
NFTA_HASH_SEED,
+ NFTA_HASH_SUM,
__NFTA_HASH_MAX,
};
#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1)
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c
index b7e3b40..8ab04d9 100644
--- a/net/netfilter/nft_hash.c
+++ b/net/netfilter/nft_hash.c
@@ -23,6 +23,7 @@ struct nft_hash {
u8 len;
u32 modulus;
u32 seed;
+ u32 sum;
};
static void nft_hash_eval(const struct nft_expr *expr,
@@ -35,7 +36,7 @@ static void nft_hash_eval(const struct nft_expr *expr,
h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
- regs->data[priv->dreg] = h;
+ regs->data[priv->dreg] = priv->sum + h;
}
const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
@@ -44,6 +45,7 @@ const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
[NFTA_HASH_LEN] = { .type = NLA_U32 },
[NFTA_HASH_MODULUS] = { .type = NLA_U32 },
[NFTA_HASH_SEED] = { .type = NLA_U32 },
+ [NFTA_HASH_SUM] = { .type = NLA_U32 },
};
static int nft_hash_init(const struct nft_ctx *ctx,
@@ -60,6 +62,11 @@ static int nft_hash_init(const struct nft_ctx *ctx,
!tb[NFTA_HASH_MODULUS])
return -EINVAL;
+ if (tb[NFTA_HASH_SUM])
+ priv->sum = ntohl(nla_get_be32(tb[NFTA_HASH_SUM]));
+ else
+ priv->sum = 0;
+
priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
if (priv->sreg < 0)
return -ERANGE;
@@ -99,7 +106,9 @@ static int nft_hash_dump(struct sk_buff *skb,
goto nla_put_failure;
if (nft_dump_register(skb, NFTA_HASH_SEED, priv->seed))
goto nla_put_failure;
-
+ if (priv->sum != 0)
+ if (nft_dump_register(skb, NFTA_HASH_SUM, priv->sum))
+ goto nla_put_failure;
return 0;
nla_put_failure:
--
2.8.1
--
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