Re: [PATCH 1/3] netfilter: ctnetlink: attach expectations to unconfirmed conntracks

[Gao feng <gaofeng@cn.fujitsu.com>]

On 05/23/2013 04:42 PM, Pablo Neira Ayuso wrote:
> This patch adds the capability to attach expectations to unconfirmed
> conntrack entries. This patch is required by the DHCPv6 helper in
> user-space.
> 
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  include/net/netfilter/nf_conntrack.h               |    4 ++++
>  include/uapi/linux/netfilter/nfnetlink_conntrack.h |    1 +
>  net/netfilter/nf_conntrack_core.c                  |   20 ++++++++++++++++++++
>  net/netfilter/nf_conntrack_netlink.c               |   14 ++++++++++++--
>  4 files changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
> index 644d9c2..d172fc5 100644
> --- a/include/net/netfilter/nf_conntrack.h
> +++ b/include/net/netfilter/nf_conntrack.h
> @@ -180,6 +180,10 @@ extern struct nf_conntrack_tuple_hash *
>  __nf_conntrack_find(struct net *net, u16 zone,
>  		    const struct nf_conntrack_tuple *tuple);
>  
> +struct nf_conntrack_tuple_hash *
> +nf_ct_unconfirmed_find(struct net *net, u16 zone,
> +		       const struct nf_conntrack_tuple *tuple);
> +
>  extern int nf_conntrack_hash_check_insert(struct nf_conn *ct);
>  extern void nf_ct_delete_from_lists(struct nf_conn *ct);
>  extern void nf_ct_dying_timeout(struct nf_conn *ct);
> diff --git a/include/uapi/linux/netfilter/nfnetlink_conntrack.h b/include/uapi/linux/netfilter/nfnetlink_conntrack.h
> index 08fabc6..8f7c2fe 100644
> --- a/include/uapi/linux/netfilter/nfnetlink_conntrack.h
> +++ b/include/uapi/linux/netfilter/nfnetlink_conntrack.h
> @@ -187,6 +187,7 @@ enum ctattr_expect {
>  	CTA_EXPECT_CLASS,
>  	CTA_EXPECT_NAT,
>  	CTA_EXPECT_FN,
> +	CTA_EXPECT_MASTER_STATUS,
>  	__CTA_EXPECT_MAX
>  };
>  #define CTA_EXPECT_MAX (__CTA_EXPECT_MAX - 1)
> diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
> index ebb81d6..a6e5764 100644
> --- a/net/netfilter/nf_conntrack_core.c
> +++ b/net/netfilter/nf_conntrack_core.c
> @@ -401,6 +401,26 @@ nf_conntrack_find_get(struct net *net, u16 zone,
>  }
>  EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
>  
> +struct nf_conntrack_tuple_hash *
> +nf_ct_unconfirmed_find(struct net *net, u16 zone,
> +		       const struct nf_conntrack_tuple *tuple)
> +{
> +	struct nf_conntrack_tuple_hash *h, *ret = NULL;
> +	struct hlist_nulls_node *n;
> +
> +	rcu_read_lock();
> +	hlist_nulls_for_each_entry_rcu(h, n, &net->ct.unconfirmed, hnnode) {
> +		if (nf_ct_tuple_equal(tuple, &h->tuple) &&
> +		    nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)) == zone) {
> +			ret = h;

Shouldn't we get reference of nf_ct_tuplehash_to_ctrack(h) here?
ctnetlink_create_expect will call nf_ct_put to release the reference finally.

or I miss something?

> +			break;
> +		}
> +	}
> +	rcu_read_unlock();
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(nf_ct_unconfirmed_find);
> +
>  static void __nf_conntrack_hash_insert(struct nf_conn *ct,
>  				       unsigned int hash,
>  				       unsigned int repl_hash)
> diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> index 6d0f8a1..3596682 100644
> --- a/net/netfilter/nf_conntrack_netlink.c
> +++ b/net/netfilter/nf_conntrack_netlink.c
> @@ -2742,7 +2742,7 @@ ctnetlink_create_expect(struct net *net, u16 zone,
>  	struct nf_conn *ct;
>  	struct nf_conn_help *help;
>  	struct nf_conntrack_helper *helper = NULL;
> -	u_int32_t class = 0;
> +	u_int32_t class = 0, master_status;
>  	int err = 0;
>  
>  	/* caller guarantees that those three CTA_EXPECT_* exist */
> @@ -2756,8 +2756,18 @@ ctnetlink_create_expect(struct net *net, u16 zone,
>  	if (err < 0)
>  		return err;
>  
> +	if (cda[CTA_EXPECT_MASTER_STATUS]) {
> +		master_status =
> +			ntohl(nla_get_be32(cda[CTA_EXPECT_MASTER_STATUS]));
> +	} else
> +		master_status = IPS_CONFIRMED;
> +
>  	/* Look for master conntrack of this expectation */
> -	h = nf_conntrack_find_get(net, zone, &master_tuple);
> +	if (master_status & IPS_CONFIRMED)
> +		h = nf_conntrack_find_get(net, zone, &master_tuple);
> +	else
> +		h = nf_ct_unconfirmed_find(net, zone, &master_tuple);
> +
>  	if (!h)
>  		return -ENOENT;
>  	ct = nf_ct_tuplehash_to_ctrack(h);
>