From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laura Garcia Subject: Re: [PATCH] netfilter: nft_hash: Add hash offset value Date: Mon, 5 Sep 2016 11:58:24 +0200 Message-ID: <20160905095823.GA23680@sonyv> References: <20160905083655.GA15395@sonyv> <20160905091028.GA2469@salvia> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netfilter-devel@vger.kernel.org To: Pablo Neira Ayuso Return-path: Received: from mail-wm0-f67.google.com ([74.125.82.67]:35654 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932444AbcIEJ6b (ORCPT ); Mon, 5 Sep 2016 05:58:31 -0400 Received: by mail-wm0-f67.google.com with SMTP id a6so1213821wmc.2 for ; Mon, 05 Sep 2016 02:58:30 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20160905091028.GA2469@salvia> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Mon, Sep 05, 2016 at 11:10:28AM +0200, Pablo Neira Ayuso wrote: > On Mon, Sep 05, 2016 at 10:36:57AM +0200, Laura Garcia Liebana wrote: > > 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 > > --- > > 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; > > There is a corner case that we should reject from the kernel, I think > this is: > > if (priv->sum + priv->modulus - 1 < priv->sum) > return -EOVERFLOW; > > We'll handle this from userspace anyway too, but I think it's easy to > reject this crazy this. Such case shouldn't happen cause the modulus must be > 1. The init() provides: priv->modulus = ntohl(nla_get_be32(tb[NFTA_HASH_MODULUS])); if (priv->modulus <= 1) return -ERANGE;