diff options
author | Laura Garcia Liebana <nevola@gmail.com> | 2017-03-02 17:00:14 +0100 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2017-03-06 17:57:42 +0100 |
commit | 3206caded81ad9bdb2e7ff4c0b94ec5913df8618 (patch) | |
tree | 571af47f0aabf798126bcff7ac8650b2f8dac99e /net/netfilter/nft_hash.c | |
parent | 511040eea2234d9add3f33ba0e6c2e17944fdfb6 (diff) |
netfilter: nft_hash: support of symmetric hash
This patch provides symmetric hash support according to source
ip address and port, and destination ip address and port.
For this purpose, the __skb_get_hash_symmetric() is used to
identify the flow as it uses FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL
flag by default.
The new attribute NFTA_HASH_TYPE has been included to support
different types of hashing functions. Currently supported
NFT_HASH_JENKINS through jhash and NFT_HASH_SYM through symhash.
The main difference between both types are:
- jhash requires an expression with sreg, symhash doesn't.
- symhash supports modulus and offset, but not seed.
Examples:
nft add rule ip nat prerouting ct mark set jhash ip saddr mod 2
nft add rule ip nat prerouting ct mark set symhash mod 2
By default, jenkins hash will be used if no hash type is
provided for compatibility reasons.
Signed-off-by: Laura Garcia Liebana <laura.garcia@zevenet.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/nft_hash.c')
-rw-r--r-- | net/netfilter/nft_hash.c | 99 |
1 files changed, 98 insertions, 1 deletions
diff --git a/net/netfilter/nft_hash.c b/net/netfilter/nft_hash.c index ccb834ef049b..a6a4633725bb 100644 --- a/net/netfilter/nft_hash.c +++ b/net/netfilter/nft_hash.c @@ -38,6 +38,25 @@ static void nft_jhash_eval(const struct nft_expr *expr, regs->data[priv->dreg] = h + priv->offset; } +struct nft_symhash { + enum nft_registers dreg:8; + u32 modulus; + u32 offset; +}; + +static void nft_symhash_eval(const struct nft_expr *expr, + struct nft_regs *regs, + const struct nft_pktinfo *pkt) +{ + struct nft_symhash *priv = nft_expr_priv(expr); + struct sk_buff *skb = pkt->skb; + u32 h; + + h = reciprocal_scale(__skb_get_hash_symmetric(skb), priv->modulus); + + regs->data[priv->dreg] = h + priv->offset; +} + static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { [NFTA_HASH_SREG] = { .type = NLA_U32 }, [NFTA_HASH_DREG] = { .type = NLA_U32 }, @@ -45,6 +64,7 @@ static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { [NFTA_HASH_MODULUS] = { .type = NLA_U32 }, [NFTA_HASH_SEED] = { .type = NLA_U32 }, [NFTA_HASH_OFFSET] = { .type = NLA_U32 }, + [NFTA_HASH_TYPE] = { .type = NLA_U32 }, }; static int nft_jhash_init(const struct nft_ctx *ctx, @@ -92,6 +112,32 @@ static int nft_jhash_init(const struct nft_ctx *ctx, NFT_DATA_VALUE, sizeof(u32)); } +static int nft_symhash_init(const struct nft_ctx *ctx, + const struct nft_expr *expr, + const struct nlattr * const tb[]) +{ + struct nft_symhash *priv = nft_expr_priv(expr); + + if (!tb[NFTA_HASH_DREG] || + !tb[NFTA_HASH_MODULUS]) + return -EINVAL; + + if (tb[NFTA_HASH_OFFSET]) + priv->offset = ntohl(nla_get_be32(tb[NFTA_HASH_OFFSET])); + + priv->dreg = nft_parse_register(tb[NFTA_HASH_DREG]); + + priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); + if (priv->modulus <= 1) + return -ERANGE; + + if (priv->offset + priv->modulus - 1 < priv->offset) + return -EOVERFLOW; + + return nft_validate_register_store(ctx, priv->dreg, NULL, + NFT_DATA_VALUE, sizeof(u32)); +} + static int nft_jhash_dump(struct sk_buff *skb, const struct nft_expr *expr) { @@ -110,6 +156,28 @@ static int nft_jhash_dump(struct sk_buff *skb, if (priv->offset != 0) if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) goto nla_put_failure; + if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_JENKINS))) + goto nla_put_failure; + return 0; + +nla_put_failure: + return -1; +} + +static int nft_symhash_dump(struct sk_buff *skb, + const struct nft_expr *expr) +{ + const struct nft_symhash *priv = nft_expr_priv(expr); + + if (nft_dump_register(skb, NFTA_HASH_DREG, priv->dreg)) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_HASH_MODULUS, htonl(priv->modulus))) + goto nla_put_failure; + if (priv->offset != 0) + if (nla_put_be32(skb, NFTA_HASH_OFFSET, htonl(priv->offset))) + goto nla_put_failure; + if (nla_put_be32(skb, NFTA_HASH_TYPE, htonl(NFT_HASH_SYM))) + goto nla_put_failure; return 0; nla_put_failure: @@ -125,9 +193,38 @@ static const struct nft_expr_ops nft_jhash_ops = { .dump = nft_jhash_dump, }; +static const struct nft_expr_ops nft_symhash_ops = { + .type = &nft_hash_type, + .size = NFT_EXPR_SIZE(sizeof(struct nft_symhash)), + .eval = nft_symhash_eval, + .init = nft_symhash_init, + .dump = nft_symhash_dump, +}; + +static const struct nft_expr_ops * +nft_hash_select_ops(const struct nft_ctx *ctx, + const struct nlattr * const tb[]) +{ + u32 type; + + if (!tb[NFTA_HASH_TYPE]) + return &nft_jhash_ops; + + type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE])); + switch (type) { + case NFT_HASH_SYM: + return &nft_symhash_ops; + case NFT_HASH_JENKINS: + return &nft_jhash_ops; + default: + break; + } + return ERR_PTR(-EOPNOTSUPP); +} + static struct nft_expr_type nft_hash_type __read_mostly = { .name = "hash", - .ops = &nft_jhash_ops, + .select_ops = &nft_hash_select_ops, .policy = nft_hash_policy, .maxattr = NFTA_HASH_MAX, .owner = THIS_MODULE, |