diff options
| author | Laura Garcia Liebana <nevola@gmail.com> | 2016-09-06 08:44:19 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-09-12 18:37:12 +0200 |
| commit | 70ca767ea1b2748f45e96192400e515dddbe517c (patch) | |
| tree | 8888737ffc4c3ad54156568184c646318bed2a2f | |
| parent | 3c15b8e112d7351b2586c649a759318548523364 (diff) | |
netfilter: nft_hash: Add hash offset value
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 offset 100
This option generates marks according to the source address from 100 to
101.
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
| -rw-r--r-- | include/uapi/linux/netfilter/nf_tables.h | 2 | ||||
| -rw-r--r-- | net/netfilter/nft_hash.c | 17 |
2 files changed, 15 insertions, 4 deletions
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h index 24161e25576d..8c653bbd1ead 100644 --- a/include/uapi/linux/netfilter/nf_tables.h +++ b/include/uapi/linux/netfilter/nf_tables.h @@ -731,6 +731,7 @@ 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_OFFSET: add this offset value to hash result (NLA_U32) */ enum nft_hash_attributes { NFTA_HASH_UNSPEC, @@ -739,6 +740,7 @@ enum nft_hash_attributes { NFTA_HASH_LEN, NFTA_HASH_MODULUS, NFTA_HASH_SEED, + NFTA_HASH_OFFSET, __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 764251d31e46..bd12f7a801c2 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 offset; }; static void nft_hash_eval(const struct nft_expr *expr, @@ -31,10 +32,10 @@ static void nft_hash_eval(const struct nft_expr *expr, { struct nft_hash *priv = nft_expr_priv(expr); const void *data = ®s->data[priv->sreg]; + u32 h; - regs->data[priv->dreg] = - reciprocal_scale(jhash(data, priv->len, priv->seed), - priv->modulus); + h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus); + regs->data[priv->dreg] = h + priv->offset; } static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { @@ -59,6 +60,9 @@ static int nft_hash_init(const struct nft_ctx *ctx, !tb[NFTA_HASH_MODULUS]) return -EINVAL; + if (tb[NFTA_HASH_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET])); + priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]); priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); @@ -72,6 +76,9 @@ static int nft_hash_init(const struct nft_ctx *ctx, if (priv->modulus <= 1) return -ERANGE; + if (priv->offset + priv->modulus - 1 < U32_MAX) + return -EOVERFLOW; + priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED])); return nft_validate_register_load(priv->sreg, len) && @@ -94,7 +101,9 @@ static int nft_hash_dump(struct sk_buff *skb, goto nla_put_failure; if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed))) goto nla_put_failure; - + if (priv->offset != 0) + if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) + goto nla_put_failure; return 0; nla_put_failure: |