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

[Joe Stringer]

On 30 September 2015 at 17:31, Pravin Shelar <pshelar@xxxxxxxxxx> wrote:
> 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.

Already handled by ovs_ct_verify() in conntrack.h.
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