Re: [PATCH net 5/7] openvswitch: Reject ct_state unsupported bits

[Pravin Shelar]

On Tue, Sep 29, 2015 at 3:39 PM, Joe Stringer <joestringer@xxxxxxxxxx> wrote:
> Previously, if userspace specified ct_state bits in the flow key which
> are currently undefined (and therefore unsupported), then they would be
> ignored. This could cause unexpected behaviour in future if userspace is
> extended to support additional bits but attempts to communicate with the
> current version of the kernel. This patch rectifies the situation by
> rejecting such ct_state bits.
>
> Fixes: 7f8a436 "openvswitch: Add conntrack action"
> Signed-off-by: Joe Stringer <joestringer@xxxxxxxxxx>
> ---
>  net/openvswitch/conntrack.h    | 12 ++++++++++++
>  net/openvswitch/flow_netlink.c |  6 ++++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/net/openvswitch/conntrack.h b/net/openvswitch/conntrack.h
> index 43f5dd7..c658d95 100644
> --- a/net/openvswitch/conntrack.h
> +++ b/net/openvswitch/conntrack.h
> @@ -34,6 +34,13 @@ int ovs_ct_execute(struct net *, struct sk_buff *, struct sw_flow_key *,
>  void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key);
>  int ovs_ct_put_key(const struct sw_flow_key *key, struct sk_buff *skb);
>  void ovs_ct_free_action(const struct nlattr *a);
> +
> +static inline bool ovs_ct_state_supported(u8 state)
> +{
> +       return !(state & ~(OVS_CS_F_NEW | OVS_CS_F_ESTABLISHED |
> +                        OVS_CS_F_RELATED | OVS_CS_F_REPLY_DIR |
> +                        OVS_CS_F_INVALID | OVS_CS_F_TRACKED));
> +}
>  #else
>  #include <linux/errno.h>
>
> @@ -46,6 +53,11 @@ static inline bool ovs_ct_verify(struct net *net, int attr)
>         return false;
>  }
>
> +static inline bool ovs_ct_state_supported(u8 state)
> +{
> +       return false;
> +}
> +
>  static inline int ovs_ct_copy_action(struct net *net, const struct nlattr *nla,
>                                      const struct sw_flow_key *key,
>                                      struct sw_flow_actions **acts, bool log)
> diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
> index ea82cd5..c4917c9 100644
> --- a/net/openvswitch/flow_netlink.c
> +++ b/net/openvswitch/flow_netlink.c
> @@ -816,6 +816,12 @@ static int metadata_from_nlattrs(struct net *net, struct sw_flow_match *match,
>             ovs_ct_verify(net, OVS_KEY_ATTR_CT_STATE)) {
>                 u8 ct_state = nla_get_u8(a[OVS_KEY_ATTR_CT_STATE]);
>
We also need to return error if kernel does not support the feature.

> +               if (!is_mask && !ovs_ct_state_supported(ct_state)) {
> +                       OVS_NLERR(log, "ct_state flags %02x unsupported",
> +                                 ct_state);
> +                       return -EINVAL;
> +               }
> +
>                 SW_FLOW_KEY_PUT(match, ct.state, ct_state, is_mask);
>                 *attrs &= ~(1ULL << OVS_KEY_ATTR_CT_STATE);
>         }
> --
> 2.1.4
>
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