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ovn: Fix IPv6 DAD failure for container ports
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When a container port is created inside a VM, the below kernel message
is seen and IPv6 doesn't work on that interface.

[  138.000753] IPv6: vlan4: IPv6 duplicate address <IPv6 LLA> detected!

When a container port sends a ethernet broadcast packet, OVN delivers the same
packet back to the child port (and hence the DAD check fails).

This is because
 - 'MLF_ALLOW_LOOPBACK_BIT' is set in REG10 in table 0 for the packets received
   from any child port.
 - for ethernet broadcast packets, Table 33 (OFTABLE_LOCAL_OUTPUT) clones the
   packet for every local port 'P' which belongs to the same datapath i.e
   'P'->REG15, resubmit(,34)
 - If REG14 and REG15 are same, Table 34 (OFTABLE_CHECK_LOOPBACK) drops the packet
   if 'MLF_ALLOW_LOOPBACK_BIT' is not set.
 - But in the case of container ports, this bit will be set and hence doesn't gets
   dropped and eventually gets delivered to the source container port.
 - The VM's kernel thinks its a DAD packet. The latest kernels (4.19) implements
   the RFC -7527 (enhanced DAD), but it is still a problem for older kernels.

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 so that Table 34 drops the packet for the source port.

Signed-off-by: Numan Siddique <[email protected]>
Signed-off-by: Gurucharan Shetty <[email protected]>
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@numansiddique @shettyg
numansiddique authored and shettyg committed Oct 11, 2018
1 parent 1adcbce commit 22e506d
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Showing 5 changed files with 97 additions and 17 deletions.
29 changes: 20 additions & 9 deletions ovn/controller/ofctrl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -644,20 +646,29 @@ 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;
}

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. */

Expand Down
5 changes: 5 additions & 0 deletions ovn/controller/ofctrl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
65 changes: 57 additions & 8 deletions ovn/controller/physical.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -244,11 +245,19 @@ put_local_common_flows(uint32_t dp_key, uint32_t port_key,
/* Table 64, Priority 100.
* =======================
*
* If the packet is supposed to hair-pin because the "loopback"
* flag is set (or if the destination is a nested container),
* If the packet is supposed to hair-pin because the
* - "loopback" flag is set
* - or if the destination is a nested container
* - or if "nested_container" flag is set and the destination is the
* parent port,
* temporarily set the in_port to zero, resubmit to
* table 65 for logical-to-physical translation, then restore
* the port number. */
* the port number.
*
* If 'parent_port_key' is set, then the 'port_key' represents a nested
* container. */

bool nested_container = parent_port_key ? true: false;
match_init_catchall(&match);
ofpbuf_clear(ofpacts_p);
match_set_metadata(&match, htonll(dp_key));
Expand All @@ -264,6 +273,38 @@ 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);

if (nested_container) {
/* It's a nested container and when the packet from the nested
* container is to be sent to the parent port, "nested_container"
* flag will be set. We need to temporarily set the in_port to zero
* as mentioned in the comment above.
*
* If a parent port has multiple child ports, then this if condition
* will be hit multiple times, but we want to add only one flow.
* ofctrl_add_flow() logs a warning message for duplicate flows.
* So use the function 'ofctrl_check_and_add_flow' which doesn't
* log a warning.
*
* Other option is to add this flow for all the ports which are not
* nested containers. In which case we will add this flow for all the
* ports even if they don't have any child ports which is
* unnecessary.
*/
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));
ofctrl_check_and_add_flow(flow_table, OFTABLE_SAVE_INPORT, 100, 0,
&match, ofpacts_p, false);
}
}

static void
Expand Down Expand Up @@ -328,7 +369,7 @@ 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);
Expand Down Expand Up @@ -452,6 +493,7 @@ 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) {
Expand All @@ -463,6 +505,8 @@ 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,
Expand Down Expand Up @@ -523,7 +567,10 @@ 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;
/* Pass the parent port tunnel key if the port is a nested
* container. */
put_local_common_flows(dp_key, port_key, parent_port_key, &zone_ids,
ofpacts_p, flow_table);

/* Table 0, Priority 150 and 100.
Expand Down Expand Up @@ -553,8 +600,10 @@ 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);
}
Expand Down
4 changes: 4 additions & 0 deletions ovn/lib/logical-fields.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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 was received from a nested container. */
MLF_NESTED_CONTAINER = (1 << MLF_NESTED_CONTAINER_BIT),
};

#endif /* ovn/lib/logical-fields.h */
11 changes: 11 additions & 0 deletions tests/ovn.at
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7039,6 +7039,17 @@ 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
Expand Down

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