[ovs-dev,v4] ofproto-dpif-xlate: fix zone set from non-frozen-metadata fields

CT zone could be set from a field that is not included in frozen
metadata. Consider the example rules which are typically seen in
OpenStack security group rules:

priority=100,in_port=1,tcp,ct_state=-trk,action=ct(zone=5,table=0)
priority=100,in_port=1,tcp,ct_state=+trk,action=ct(commit,zone=NXM_NX_CT_ZONE[]),2

The zone is set from the first rule's ct action. These two rules will
generate two megaflows: the first one uses zone=5 to query the CT module,
the second one sets the zone-id from the first megaflow and commit to CT.

The current implementation will generate a megaflow that does not use
ct_zone=5 as a match, but directly commit into the ct using zone=5, as zone is
set by an Imm not a field.

Consider a situation that one changes the zone id (for example to 15)
in the first rule, however, still keep the second rule unchanged. During
this change, there is traffic hitting the two generated megaflows, the
revaldiator would revalidate all megaflows, however, the revalidator will
not change the second megaflow, because zone=5 is recorded in the
megaflow, so the xlate will still translate the commit action into zone=5,
and the new traffic will still commit to CT as zone=5, not zone=15,
resulting in taffic drops and other issues.

Just like OVS set-field convention, if a field X is set by Y
(Y is a variable not an Imm), we should also mask Y as a match
in the generated megaflow. An exception is that if the zone-id is
set by the field that is included in the frozen state (i.e. regs) and this
upcall is a resume of a thawed xlate, the un-wildcarding can be skipped,
as the recirc_id is a hash of the values in these fields, and it will change
following the changes of these fields. When the recirc_id changes,
all megaflows with the old recirc id will be invalid later.

Fixes: 07659514c3 ("Add support for connection tracking.")
Reported-by: Sai Su <susai.ss@bytedance.com>
Signed-off-by: Peng He <hepeng.0320@bytedance.com>
Acked-by: Mark D. Gray <mark.d.gray@redhat.com>
---
 include/openvswitch/meta-flow.h |  1 +
 lib/meta-flow.c                 | 13 +++++
 ofproto/ofproto-dpif-xlate.c    | 32 +++++++++----
 tests/system-traffic.at         | 85 +++++++++++++++++++++++++++++++++
 4 files changed, 123 insertions(+), 8 deletions(-)

Bleep bloop.  Greetings Peng He, I am a robot and I have tried out your patch.
Thanks for your contribution.

I encountered some error that I wasn't expecting.  See the details below.


checkpatch:
ERROR: Author Peng He <xnhp0320@gmail.com> needs to sign off.
WARNING: Unexpected sign-offs from developers who are not authors or co-authors or committers: Peng He <hepeng.0320@bytedance.com>
Lines checked: 236, Warnings: 1, Errors: 1


Please check this out.  If you feel there has been an error, please email aconole@redhat.com

Thanks,
0-day Robot

On 8/1/21 15:09, Peng He wrote:
> CT zone could be set from a field that is not included in frozen
> metadata. Consider the example rules which are typically seen in
> OpenStack security group rules:
> 
> priority=100,in_port=1,tcp,ct_state=-trk,action=ct(zone=5,table=0)
> priority=100,in_port=1,tcp,ct_state=+trk,action=ct(commit,zone=NXM_NX_CT_ZONE[]),2
> 
> The zone is set from the first rule's ct action. These two rules will
> generate two megaflows: the first one uses zone=5 to query the CT module,
> the second one sets the zone-id from the first megaflow and commit to CT.
> 
> The current implementation will generate a megaflow that does not use
> ct_zone=5 as a match, but directly commit into the ct using zone=5, as zone is
> set by an Imm not a field.
> 
> Consider a situation that one changes the zone id (for example to 15)
> in the first rule, however, still keep the second rule unchanged. During
> this change, there is traffic hitting the two generated megaflows, the
> revaldiator would revalidate all megaflows, however, the revalidator will
> not change the second megaflow, because zone=5 is recorded in the
> megaflow, so the xlate will still translate the commit action into zone=5,
> and the new traffic will still commit to CT as zone=5, not zone=15,
> resulting in taffic drops and other issues.
> 
> Just like OVS set-field convention, if a field X is set by Y
> (Y is a variable not an Imm), we should also mask Y as a match
> in the generated megaflow. An exception is that if the zone-id is
> set by the field that is included in the frozen state (i.e. regs) and this
> upcall is a resume of a thawed xlate, the un-wildcarding can be skipped,
> as the recirc_id is a hash of the values in these fields, and it will change
> following the changes of these fields. When the recirc_id changes,
> all megaflows with the old recirc id will be invalid later.
> 
> Fixes: 07659514c3 ("Add support for connection tracking.")
> Reported-by: Sai Su <susai.ss@bytedance.com>
> Signed-off-by: Peng He <hepeng.0320@bytedance.com>
> Acked-by: Mark D. Gray <mark.d.gray@redhat.com>
> ---
>  include/openvswitch/meta-flow.h |  1 +
>  lib/meta-flow.c                 | 13 +++++
>  ofproto/ofproto-dpif-xlate.c    | 32 +++++++++----
>  tests/system-traffic.at         | 85 +++++++++++++++++++++++++++++++++
>  4 files changed, 123 insertions(+), 8 deletions(-)
> 
> diff --git a/include/openvswitch/meta-flow.h b/include/openvswitch/meta-flow.h
> index 95e52e358..045dce8f5 100644
> --- a/include/openvswitch/meta-flow.h
> +++ b/include/openvswitch/meta-flow.h
> @@ -2305,6 +2305,7 @@ void mf_set_flow_value_masked(const struct mf_field *,
>                                const union mf_value *mask,
>                                struct flow *);
>  bool mf_is_tun_metadata(const struct mf_field *);
> +bool mf_is_frozen_metadata(const struct mf_field *);
>  bool mf_is_pipeline_field(const struct mf_field *);
>  bool mf_is_set(const struct mf_field *, const struct flow *);
>  void mf_mask_field(const struct mf_field *, struct flow_wildcards *);
> diff --git a/lib/meta-flow.c b/lib/meta-flow.c
> index c808d205d..e03cd8d0c 100644
> --- a/lib/meta-flow.c
> +++ b/lib/meta-flow.c
> @@ -1788,6 +1788,19 @@ mf_is_tun_metadata(const struct mf_field *mf)
>             mf->id < MFF_TUN_METADATA0 + TUN_METADATA_NUM_OPTS;
>  }
>  
> +bool
> +mf_is_frozen_metadata(const struct mf_field *mf)
> +{
> +    if (mf->id >= MFF_TUN_ID && mf->id <= MFF_IN_PORT_OXM) {
> +        return true;
> +    }
> +
> +    if (mf->id >= MFF_REG0 && mf->id < MFF_ETH_SRC) {
> +        return true;
> +    }
> +    return false;
> +}
> +
>  bool
>  mf_is_pipeline_field(const struct mf_field *mf)
>  {
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index 7108c8a30..7b9f3369b 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -6177,11 +6177,32 @@ static void
>  compose_conntrack_action(struct xlate_ctx *ctx, struct ofpact_conntrack *ofc,
>                           bool is_last_action)
>  {
> -    ovs_u128 old_ct_label_mask = ctx->wc->masks.ct_label;
> -    uint32_t old_ct_mark_mask = ctx->wc->masks.ct_mark;
> -    size_t ct_offset;
>      uint16_t zone;
> +    if (ofc->zone_src.field) {
> +        union mf_subvalue value;
> +        memset(&value, 0xff, sizeof(value));
> +
> +        zone = mf_get_subfield(&ofc->zone_src, &ctx->xin->flow);
> +        if (ctx->xin->frozen_state) {
> +            /* If the upcall is a resume of a recirculation, we only need to
> +             * unwildcard the fields that are not in the frozen_metadata, as
> +             * when the rules update, OVS will generate a new recirc_id,
> +             * which will invalidate the megaflow with old the recirc_id.
> +             */
> +            if (!mf_is_frozen_metadata(ofc->zone_src.field)) {
> +                mf_write_subfield_flow(&ofc->zone_src, &value,
> +                                       &ctx->wc->masks);
> +            }
> +        } else {
> +            mf_write_subfield_flow(&ofc->zone_src, &value, &ctx->wc->masks);
> +        }
> +    } else {
> +        zone = ofc->zone_imm;
> +    }
>  
> +    size_t ct_offset;
> +    ovs_u128 old_ct_label_mask = ctx->wc->masks.ct_label;
> +    uint32_t old_ct_mark_mask = ctx->wc->masks.ct_mark;
>      /* Ensure that any prior actions are applied before composing the new
>       * conntrack action. */
>      xlate_commit_actions(ctx);
> @@ -6193,11 +6214,6 @@ compose_conntrack_action(struct xlate_ctx *ctx, struct ofpact_conntrack *ofc,
>      do_xlate_actions(ofc->actions, ofpact_ct_get_action_len(ofc), ctx,
>                       is_last_action, false);
>  
> -    if (ofc->zone_src.field) {
> -        zone = mf_get_subfield(&ofc->zone_src, &ctx->xin->flow);
> -    } else {
> -        zone = ofc->zone_imm;
> -    }
>  
>      ct_offset = nl_msg_start_nested(ctx->odp_actions, OVS_ACTION_ATTR_CT);
>      if (ofc->flags & NX_CT_F_COMMIT) {
> diff --git a/tests/system-traffic.at b/tests/system-traffic.at
> index fb5b9a36d..c3917aa0d 100644
> --- a/tests/system-traffic.at
> +++ b/tests/system-traffic.at
> @@ -1927,6 +1927,91 @@ tcp,orig=(src=10.1.1.3,dst=10.1.1.4,sport=<cleared>,dport=<cleared>),reply=(src=
>  OVS_TRAFFIC_VSWITCHD_STOP
>  AT_CLEANUP
>  
> +AT_SETUP([conntrack - zones from other field])
> +CHECK_CONNTRACK()
> +OVS_TRAFFIC_VSWITCHD_START()
> +
> +ADD_NAMESPACES(at_ns0, at_ns1)
> +
> +ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24")
> +ADD_VETH(p1, at_ns1, br0, "10.1.1.2/24")
> +
> +dnl Allow any traffic from ns0->ns1. Only allow nd, return traffic from ns1->ns0.
> +AT_DATA([flows.txt], [dnl
> +priority=1,action=drop
> +priority=10,arp,action=normal
> +priority=10,icmp,action=normal
> +priority=100,in_port=1,tcp,ct_state=-trk,action=ct(zone=5,table=0)
> +priority=100,in_port=1,tcp,ct_state=+trk,action=ct(commit,zone=NXM_NX_CT_ZONE[]),2
> +priority=100,in_port=2,ct_state=-trk,tcp,action=ct(table=0,zone=5)
> +priority=100,in_port=2,ct_state=+trk,ct_zone=5,tcp,action=1
> +])
> +
> +AT_CHECK([ovs-ofctl --bundle add-flows br0 flows.txt])
> +
> +OVS_START_L7([at_ns1], [http])
> +
> +dnl HTTP requests from p0->p1 should work fine.
> +NS_CHECK_EXEC([at_ns0], [wget 10.1.1.2 -t 3 -T 1 --retry-connrefused -v -o wget0.log])
> +
> +AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1.2)], [0], [dnl
> +tcp,orig=(src=10.1.1.1,dst=10.1.1.2,sport=<cleared>,dport=<cleared>),reply=(src=10.1.1.2,dst=10.1.1.1,sport=<cleared>,dport=<cleared>),zone=5,protoinfo=(state=<cleared>)
> +])
> +
> +dnl This is to test when the zoneid is set by a field variable like NXM_NX_CT_ZONE, the OVS xlate should generate a megaflow with a form of
> +dnl "ct_zone(5), ...  actions: ct(commit, zone=5)". The match "ct_zone(5)" is needed as if we changes the zoneid into 15 in the following,
> +dnl the old "ct_zone(5), ... actions: ct(commit, zone=5)" megaflow will not get hit, and OVS will generate a new megaflow with the match "ct_zone(0xf)".
> +dnl This will make sure that the new packets are committing to zoneid 15 rather than old 5.
> +AT_CHECK([ovs-appctl dpctl/dump-flows --names filter=in_port=ovs-p0 | grep "+trk" | grep -q "ct_zone(0x5)" ], [0], [])
> +
> +AT_CHECK([ovs-ofctl mod-flows br0 'priority=100,ct_state=-trk,tcp,in_port="ovs-p0" actions=ct(table=0,zone=15)'])
> +NS_CHECK_EXEC([at_ns0], [wget 10.1.1.2 -t 3 -T 1 --retry-connrefused -v -o wget0.log])
> +AT_CHECK([ovs-appctl dpctl/dump-flows --names filter=in_port=ovs-p0 | grep "+trk" | grep -q "ct_zone(0xf)" ], [0], [])
> +
> +OVS_TRAFFIC_VSWITCHD_STOP
> +AT_CLEANUP
> +
> +
> +AT_SETUP([conntrack - zones from other field, more tests])
> +CHECK_CONNTRACK()
> +OVS_TRAFFIC_VSWITCHD_START()
> +
> +ADD_NAMESPACES(at_ns0, at_ns1)
> +
> +ADD_VETH(p0, at_ns0, br0, "10.1.1.1/24")
> +ADD_VETH(p1, at_ns1, br0, "10.1.1.2/24")
> +
> +dnl Allow any traffic from ns0->ns1. Only allow nd, return traffic from ns1->ns0.
> +AT_DATA([flows.txt], [dnl
> +priority=1,action=drop
> +priority=10,arp,action=normal
> +priority=10,icmp,action=normal
> +priority=100,in_port=1,tcp,ct_state=-trk,action=ct(zone=5,table=0,commit,exec(load:0xffff0005->NXM_NX_CT_LABEL[[0..31]]))
> +priority=100,in_port=1,tcp,ct_state=+trk,action=ct(commit,zone=NXM_NX_CT_LABEL[[0..15]]),2
> +priority=100,in_port=2,ct_state=-trk,tcp,action=ct(table=0,zone=5)
> +priority=100,in_port=2,ct_state=+trk,ct_zone=5,tcp,action=1
> +])
> +
> +AT_CHECK([ovs-ofctl --bundle add-flows br0 flows.txt])
> +
> +OVS_START_L7([at_ns1], [http])
> +
> +dnl HTTP requests from p0->p1 should work fine.
> +NS_CHECK_EXEC([at_ns0], [wget 10.1.1.2 -t 3 -T 1 --retry-connrefused -v -o wget0.log])
> +
> +AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.1.1.2)], [0], [dnl
> +tcp,orig=(src=10.1.1.1,dst=10.1.1.2,sport=<cleared>,dport=<cleared>),reply=(src=10.1.1.2,dst=10.1.1.1,sport=<cleared>,dport=<cleared>),zone=5,labels=0xffff0005,protoinfo=(state=<cleared>)
> +])
> +
> +AT_CHECK([ovs-appctl dpctl/dump-flows --names filter=in_port=ovs-p0 | grep "+trk" | grep -q "ct_label(0xffff0005/0xffff)" ], [0], [])
> +
> +AT_CHECK([ovs-ofctl mod-flows br0 'priority=100,ct_state=-trk,tcp,in_port="ovs-p0" actions=ct(table=0,zone=15,commit,exec(load:0xffff000f->NXM_NX_CT_LABEL[[0..31]]))'])
> +NS_CHECK_EXEC([at_ns0], [wget 10.1.1.2 -t 3 -T 1 --retry-connrefused -v -o wget0.log])
> +AT_CHECK([ovs-appctl dpctl/dump-flows --names filter=in_port=ovs-p0 | grep "+trk" | grep -q "ct_label(0xffff00ff/0xffff)" ], [0], [])

Hi.  Sorry it took so long.

I re-run all the tests and this version seems to behave as expected.
Except for a typo? in a second test where it should be 0xffff000f
instead of 0xffff00ff.  I fixed that.  I also had to add one additional
'sed' to the second test in order to normalize the output between
kernel and userspace datapaths (kernel clears non-masked bits while
returning a datapath flow while userspace doesn't).

With that, applied and backported down to 2.13.

Best regards, Ilya Maximets.