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>
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@ -731,6 +731,7 @@ enum nft_meta_keys {
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* @NFTA_HASH_LEN: source data length (NLA_U32)
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* @NFTA_HASH_MODULUS: modulus value (NLA_U32)
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* @NFTA_HASH_SEED: seed value (NLA_U32)
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* @NFTA_HASH_OFFSET: add this offset value to hash result (NLA_U32)
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*/
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enum nft_hash_attributes {
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NFTA_HASH_UNSPEC,
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@ -739,6 +740,7 @@ enum nft_hash_attributes {
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NFTA_HASH_LEN,
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NFTA_HASH_MODULUS,
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NFTA_HASH_SEED,
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NFTA_HASH_OFFSET,
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__NFTA_HASH_MAX,
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};
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#define NFTA_HASH_MAX (__NFTA_HASH_MAX - 1)
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@ -23,6 +23,7 @@ struct nft_hash {
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u8 len;
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u32 modulus;
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u32 seed;
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u32 offset;
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};
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static void nft_hash_eval(const struct nft_expr *expr,
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@ -31,10 +32,10 @@ static void nft_hash_eval(const struct nft_expr *expr,
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{
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struct nft_hash *priv = nft_expr_priv(expr);
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const void *data = ®s->data[priv->sreg];
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u32 h;
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regs->data[priv->dreg] =
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reciprocal_scale(jhash(data, priv->len, priv->seed),
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priv->modulus);
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h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);
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regs->data[priv->dreg] = h + priv->offset;
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}
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static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {
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@ -59,6 +60,9 @@ static int nft_hash_init(const struct nft_ctx *ctx,
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!tb[NFTA_HASH_MODULUS])
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return -EINVAL;
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if (tb[NFTA_HASH_OFFSET])
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priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET]));
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priv->sreg = nft_parse_register(tb[NFTA_HASH_SREG]);
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priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]);
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@ -72,6 +76,9 @@ static int nft_hash_init(const struct nft_ctx *ctx,
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if (priv->modulus <= 1)
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return -ERANGE;
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if (priv->offset + priv->modulus - 1 < U32_MAX)
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return -EOVERFLOW;
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priv->seed = ntohl(nla_get_be32(tb[NFTA_HASH_SEED]));
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return nft_validate_register_load(priv->sreg, len) &&
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@ -94,7 +101,9 @@ static int nft_hash_dump(struct sk_buff *skb,
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goto nla_put_failure;
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if (nla_put_be32(skb, NFTA_HASH_SEED, htonl(priv->seed)))
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goto nla_put_failure;
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if (priv->offset != 0)
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if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset)))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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