[ovs-dev] [PATCH] ovn: Fix IPv6 DAD failure for child ports

Numan Siddique nusiddiq at redhat.com
Thu Oct 4 20:28:53 UTC 2018


Thanks for the review Guru.

Please see below for the comments.



On Fri, Oct 5, 2018 at 12:09 AM Guru Shetty <guru at ovn.org> wrote:

>
>
> On Mon, 17 Sep 2018 at 02:24, <nusiddiq at redhat.com> wrote:
>
>> From: Numan Siddique <nusiddiq at redhat.com>
>>
>> When a child vlan interface is created inside a VM, the below kernel
>> message
>> is seen and IPv6 doesn't work on that interface.
>>
>
> On which interface doesn't IPv6 work? On the Vm's interface or on the
> container's interface?
>
>

It is seen on the container's interface.

>
>> [  138.000753] IPv6: vlan4: IPv6 duplicate address <IPv6 LLA> detected!
>>
>> When a child port sends a broadcast packet, OVN delivers the same
>> packet back to the child port (and hence the DAD check fails).
>>
>
> Is this limited to IP broadcast only? Or does this happen with mac
> broadcast too? (I am surprised why I hadn't seen this behavior with ARP
> packets of containers).
>

It happens with mac broadcast. You can actually reproduce the issue by
applying the code in tests/ovn.at without this patch.

Looks like I have confused you with the patch.  Let me try to give an
example. Suppose we have switch - sw0 - with ports p1, p2 and p3 and all of
them reside in the same chassis.
When p1 sends a broadcast/multicast packet, the below logical flow is hit

table=17(ls_in_l2_lkup      ), priority=100  , match=(eth.mcast),
action=(outport = "_MC_flood"; output;)

This translates to the OF flow
- metadata=0x1,dl_dst=01:00:00:00:00:00/01:00:00:00:00:00
actions=load:0xffff->NXM_NX_REG15[],resubmit(,32)

In the table 33 if reg15 has 0xffff, it will resubmit the flow with reg15
set to each logical port

i.e reg15=0xffff,metadata=0x1
actions=load:0x1->NXM_NX_REG15[],resubmit(,34),load:0x2>NXM_NX_REG15[],resubmit(,34),load:0x3->NXM_NX_REG15[],resubmit(,34),load:0xffff->NXM_NX_REG15[]

In the normal case, the packet will not be delivered back to p1 and instead
will be dropped in table 34 (OFTABLE_CHECK_LOOPBACK)  since reg10[0] is not
set.

table=34, n_packets=0, n_bytes=0,
priority=100,reg10=0/0x1,reg14=0x2,reg15=0x2,metadata=0x1 actions=drop

When the register reg10[0] is set, it means the packet needs to be loop
backed to the source port. So table 64 has flows to clear the in_port
i,.e
table=64,  priority=100,reg10=0x1/0x1,reg15=0x1,metadata=0x1
actions=push:NXM_OF_IN_PORT[],load:0->NXM_OF_IN_PORT[],resubmit(,65),pop:NXM_OF_IN_PORT[]

Now if we take the example of child ports, let's say "p2" is the child port
of "p1" and in_port of p1 is 1
In table 0, we will see 2 flows for in_port=1

match=(in_port=1) -
actions=(load:0x1->OXM_OF_METADATA[],load:0x1->NXM_NX_REG14[] and submit to
table 8)
match=(in_port=1, dl_vlan=4) actions(load:0x1->NXM_NX_REG10[0], strip_vlan,
load:0x1->OXM_OF_METADATA[],load:0x2->NXM_NX_REG14[] , and submit to table
8)

Suppose if p2 sends a braodcast packet, reg10[0] is set in table 0.

In this case, since reg10[0] is set, the broadcast packet is not dropped in
table 34 for port "p2" and it gets delivered back.
So this patch instead of using reg10[0], it uses a new register bit
-MLF_NESTED_CONTAINER_BIT

We also need to clear the in_port in table 64 if MLF_NESTED_CONTAINER_BIT
is set.

I will address the review comments and submit p2.

Hope this clears your confusion.

Thanks
Numan



>
>
> This is because 'MLF_ALLOW_LOOPBACK_BIT' is set in REG10 in table 0 when
>> the packet is received from any child port and table
>> 'OFTABLE_CHECK_LOOPBACK'
>> doesn't drop the packet.
>>
>
> I had thought that the previous tables only replicate packets to ports
> other than the inport. But I may be wrong.
> Some of my comments further down could be stupid because I may have not
> understood the problem well.
>
>
>>
>> This patch fixes the issue by using a new register bit
>> (MLF_NESTED_CONTAINER_BIT)
>> instead of 'MLF_ALLOW_LOOPBACK_BIT' and sets it in REG10 for the packets
>> received
>> from child ports.
>>
>> Signed-off-by: Numan Siddique <nusiddiq at redhat.com>
>> ---
>>  ovn/controller/ofctrl.c   | 29 ++++++++++++++++++++---------
>>  ovn/controller/ofctrl.h   |  5 +++++
>>  ovn/controller/physical.c | 38 ++++++++++++++++++++++++++++++++------
>>  ovn/lib/logical-fields.h  |  4 ++++
>>  tests/ovn.at              | 11 +++++++++++
>>  5 files changed, 72 insertions(+), 15 deletions(-)
>>
>> diff --git a/ovn/controller/ofctrl.c b/ovn/controller/ofctrl.c
>> index 96c57f143..2f2b185ae 100644
>> --- a/ovn/controller/ofctrl.c
>> +++ b/ovn/controller/ofctrl.c
>> @@ -630,9 +630,11 @@ ofctrl_recv(const struct ofp_header *oh, enum
>> ofptype type)
>>   *
>>   * The caller should initialize its own hmap to hold the flows. */
>>  void
>> -ofctrl_add_flow(struct hmap *desired_flows,
>> -                uint8_t table_id, uint16_t priority, uint64_t cookie,
>> -                const struct match *match, const struct ofpbuf *actions)
>> +ofctrl_check_and_add_flow(struct hmap *desired_flows,
>> +                          uint8_t table_id, uint16_t priority, uint64_t
>> cookie,
>> +                          const struct match *match,
>> +                          const struct ofpbuf *actions,
>> +                          bool log_duplicate_flow)
>>  {
>>      struct ovn_flow *f = xmalloc(sizeof *f);
>>      f->table_id = table_id;
>> @@ -644,13 +646,14 @@ ofctrl_add_flow(struct hmap *desired_flows,
>>      f->cookie = cookie;
>>
>>      if (ovn_flow_lookup(desired_flows, f)) {
>> -        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
>> -        if (!VLOG_DROP_DBG(&rl)) {
>> -            char *s = ovn_flow_to_string(f);
>> -            VLOG_DBG("dropping duplicate flow: %s", s);
>> -            free(s);
>> +        if (log_duplicate_flow) {
>> +            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5,
>> 5);
>> +            if (!VLOG_DROP_DBG(&rl)) {
>> +                char *s = ovn_flow_to_string(f);
>> +                VLOG_DBG("dropping duplicate flow: %s", s);
>> +                free(s);
>> +            }
>>          }
>> -
>>          ovn_flow_destroy(f);
>>          return;
>>      }
>> @@ -658,6 +661,14 @@ ofctrl_add_flow(struct hmap *desired_flows,
>>      hmap_insert(desired_flows, &f->hmap_node, f->hmap_node.hash);
>>  }
>>
>> +void
>> +ofctrl_add_flow(struct hmap *desired_flows,
>> +                uint8_t table_id, uint16_t priority, uint64_t cookie,
>> +                const struct match *match, const struct ofpbuf *actions)
>> +{
>> +    ofctrl_check_and_add_flow(desired_flows, table_id, priority, cookie,
>> +                              match, actions, true);
>> +}
>>
>>  /* ovn_flow. */
>>
>> diff --git a/ovn/controller/ofctrl.h b/ovn/controller/ofctrl.h
>> index e3fc95b05..ae0cfa513 100644
>> --- a/ovn/controller/ofctrl.h
>> +++ b/ovn/controller/ofctrl.h
>> @@ -55,4 +55,9 @@ void ofctrl_add_flow(struct hmap *desired_flows,
>> uint8_t table_id,
>>                       uint16_t priority, uint64_t cookie,
>>                       const struct match *, const struct ofpbuf *ofpacts);
>>
>> +void ofctrl_check_and_add_flow(struct hmap *desired_flows, uint8_t
>> table_id,
>> +                               uint16_t priority, uint64_t cookie,
>> +                               const struct match *,
>> +                               const struct ofpbuf *ofpacts,
>> +                               bool log_duplicate_flow);
>>  #endif /* ovn/ofctrl.h */
>> diff --git a/ovn/controller/physical.c b/ovn/controller/physical.c
>> index c38d7b09f..d781ae459 100644
>> --- a/ovn/controller/physical.c
>> +++ b/ovn/controller/physical.c
>> @@ -189,7 +189,8 @@ get_zone_ids(const struct sbrec_port_binding *binding,
>>
>>  static void
>>  put_local_common_flows(uint32_t dp_key, uint32_t port_key,
>> -                       bool nested_container, const struct zone_ids
>> *zone_ids,
>> +                       uint32_t parent_port_key,
>> +                       const struct zone_ids *zone_ids,
>>                         struct ofpbuf *ofpacts_p, struct hmap *flow_table)
>>  {
>>      struct match match;
>> @@ -253,7 +254,7 @@ put_local_common_flows(uint32_t dp_key, uint32_t
>> port_key,
>>      ofpbuf_clear(ofpacts_p);
>>      match_set_metadata(&match, htonll(dp_key));
>>      match_set_reg(&match, MFF_LOG_OUTPORT - MFF_REG0, port_key);
>> -    if (!nested_container) {
>> +    if (!parent_port_key) {
>>          match_set_reg_masked(&match, MFF_LOG_FLAGS - MFF_REG0,
>>                               MLF_ALLOW_LOOPBACK, MLF_ALLOW_LOOPBACK);
>>      }
>>
> I think before your patch, the above code would always save inport for
> nested containers. They continue to do so now. I hope that was your
> intention?
>
>
>
>> @@ -264,6 +265,25 @@ put_local_common_flows(uint32_t dp_key, uint32_t
>> port_key,
>>      put_stack(MFF_IN_PORT, ofpact_put_STACK_POP(ofpacts_p));
>>      ofctrl_add_flow(flow_table, OFTABLE_SAVE_INPORT, 100, 0,
>>
>
>                    &match, ofpacts_p);
>>
> +
>>
> Can you add a comment here on what we are doing below?
>
> When a packet is headed to a nested container, the outport in OVN should
> be that of the destination nested container.
> But here it looks like we are matching on the OVN outport being the parent
> port and saying that if the outport is parent port, we should save the
> physical inport.
> Is that what we are doing? I don't quite understand how this helps to
> prevent packet from going back to the originator child port. I am sure I am
> missing something simple here.
>
> +    if (parent_port_key) {
>> +        match_init_catchall(&match);
>> +        ofpbuf_clear(ofpacts_p);
>> +        match_set_metadata(&match, htonll(dp_key));
>> +        match_set_reg(&match, MFF_LOG_OUTPORT - MFF_REG0,
>> parent_port_key);
>> +        match_set_reg_masked(&match, MFF_LOG_FLAGS - MFF_REG0,
>> +                             MLF_NESTED_CONTAINER, MLF_NESTED_CONTAINER);
>> +
>> +        put_stack(MFF_IN_PORT, ofpact_put_STACK_PUSH(ofpacts_p));
>> +        put_load(0, MFF_IN_PORT, 0, 16, ofpacts_p);
>> +        put_resubmit(OFTABLE_LOG_TO_PHY, ofpacts_p);
>> +        put_stack(MFF_IN_PORT, ofpact_put_STACK_POP(ofpacts_p));
>> +        /* When a parent port has multiple child ports, we don't want to
>> +         * log the duplicate flow message.
>> +         */
>> +        ofctrl_check_and_add_flow(flow_table, OFTABLE_SAVE_INPORT, 100,
>> 0,
>> +                                  &match, ofpacts_p, false);
>> +    }
>>  }
>>
>>  static void
>> @@ -328,7 +348,7 @@ consider_port_binding(struct ovsdb_idl_index
>> *sbrec_chassis_by_name,
>>          }
>>
>>          struct zone_ids binding_zones = get_zone_ids(binding, ct_zones);
>> -        put_local_common_flows(dp_key, port_key, false, &binding_zones,
>> +        put_local_common_flows(dp_key, port_key, 0, &binding_zones,
>>                                 ofpacts_p, flow_table);
>>
>>          match_init_catchall(&match);
>> @@ -452,6 +472,7 @@ consider_port_binding(struct ovsdb_idl_index
>> *sbrec_chassis_by_name,
>>
>>      int tag = 0;
>>      bool nested_container = false;
>> +    const struct sbrec_port_binding *parent_port = NULL;
>>      ofp_port_t ofport;
>>      bool is_remote = false;
>>      if (binding->parent_port && *binding->parent_port) {
>> @@ -463,6 +484,8 @@ consider_port_binding(struct ovsdb_idl_index
>> *sbrec_chassis_by_name,
>>          if (ofport) {
>>              tag = *binding->tag;
>>              nested_container = true;
>> +            parent_port = lport_lookup_by_name(
>> +                sbrec_port_binding_by_name, binding->parent_port);
>>          }
>>      } else {
>>          ofport = u16_to_ofp(simap_get(&localvif_to_ofport,
>> @@ -523,7 +546,8 @@ consider_port_binding(struct ovsdb_idl_index
>> *sbrec_chassis_by_name,
>>           */
>>
>>          struct zone_ids zone_ids = get_zone_ids(binding, ct_zones);
>> -        put_local_common_flows(dp_key, port_key, nested_container,
>> &zone_ids,
>> +        uint32_t parent_port_key = parent_port ? parent_port->tunnel_key
>> : 0;
>> +        put_local_common_flows(dp_key, port_key, parent_port_key,
>> &zone_ids,
>>                                 ofpacts_p, flow_table);
>>
>>          /* Table 0, Priority 150 and 100.
>> @@ -553,8 +577,10 @@ consider_port_binding(struct ovsdb_idl_index
>> *sbrec_chassis_by_name,
>>              if (nested_container) {
>>                  /* When a packet comes from a container sitting behind a
>>                   * parent_port, we should let it loopback to other
>> containers
>> -                 * or the parent_port itself. */
>> -                put_load(MLF_ALLOW_LOOPBACK, MFF_LOG_FLAGS, 0, 1,
>> ofpacts_p);
>> +                 * or the parent_port itself. Indicate this by setting
>> the
>> +                 * MLF_NESTED_CONTAINER_BIT in MFF_LOG_FLAGS.*/
>> +                put_load(1, MFF_LOG_FLAGS, MLF_NESTED_CONTAINER_BIT, 1,
>> +                         ofpacts_p);
>>              }
>>              ofpact_put_STRIP_VLAN(ofpacts_p);
>>          }
>> diff --git a/ovn/lib/logical-fields.h b/ovn/lib/logical-fields.h
>> index b1dbb035a..ab31327e9 100644
>> --- a/ovn/lib/logical-fields.h
>> +++ b/ovn/lib/logical-fields.h
>> @@ -50,6 +50,7 @@ enum mff_log_flags_bits {
>>      MLF_FORCE_SNAT_FOR_DNAT_BIT = 2,
>>      MLF_FORCE_SNAT_FOR_LB_BIT = 3,
>>      MLF_LOCAL_ONLY_BIT = 4,
>> +    MLF_NESTED_CONTAINER_BIT = 5,
>>  };
>>
>>  /* MFF_LOG_FLAGS_REG flag assignments */
>> @@ -75,6 +76,9 @@ enum mff_log_flags {
>>       * hypervisors should instead only be output to local targets
>>       */
>>      MLF_LOCAL_ONLY = (1 << MLF_LOCAL_ONLY_BIT),
>> +
>> +    /* Indicate that a packet has received from a nested container. */
>> +    MLF_NESTED_CONTAINER = (1 << MLF_NESTED_CONTAINER_BIT),
>>  };
>>
>>  #endif /* ovn/lib/logical-fields.h */
>> diff --git a/tests/ovn.at b/tests/ovn.at
>> index 769e09f81..a7aba5ccd 100644
>> --- a/tests/ovn.at
>> +++ b/tests/ovn.at
>> @@ -7038,6 +7038,17 @@
>> packet=${dst_mac}${src_mac}8100000208004500001c000000003f110100${src_ip}${dst_ip
>>  echo  $packet >> expected1
>>  OVN_CHECK_PACKETS([hv1/vm1-tx.pcap], [expected1])
>>
>> +# Send broadcast packet from foo1. foo1 should not receive the same
>> packet.
>> +src_mac="f00000010205"
>> +dst_mac="ffffffffffff"
>> +src_ip=`ip_to_hex 192 168 1 2`
>> +dst_ip=`ip_to_hex 255 255 255 255`
>>
>> +packet=${dst_mac}${src_mac}8100000108004500001c0000000040110000${src_ip}${dst_ip}0035111100080000
>> +as hv1 ovs-appctl netdev-dummy/receive vm1 $packet
>> +
>> +# expected packet at VM1
>> +OVN_CHECK_PACKETS([hv1/vm1-tx.pcap], [expected1])
>> +
>>  OVN_CLEANUP([hv1],[hv2])
>>
>>  AT_CLEANUP
>> --
>> 2.17.1
>>
>> _______________________________________________
>> dev mailing list
>> dev at openvswitch.org
>> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
>>
>


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