On 13/07/2023 10:09, Ido Schimmel wrote:
Add a new bridge port attribute that allows attaching a nexthop object
ID to an skb that is redirected to a backup bridge port with VLAN
tunneling enabled.
Specifically, when redirecting a known unicast packet, read the backup
nexthop ID from the bridge port that lost its carrier and set it in the
bridge control block of the skb before forwarding it via the backup
port. Note that reading the ID from the bridge port should not result in
a cache miss as the ID is added next to the 'backup_port' field that was
already accessed. After this change, the 'state' field still stays on
the first cache line, together with other data path related fields such
as 'flags and 'vlgrp':
struct net_bridge_port {
struct net_bridge * br; /* 0 8 */
struct net_device * dev; /* 8 8 */
netdevice_tracker dev_tracker; /* 16 0 */
struct list_head list; /* 16 16 */
long unsigned int flags; /* 32 8 */
struct net_bridge_vlan_group * vlgrp; /* 40 8 */
struct net_bridge_port * backup_port; /* 48 8 */
u32 backup_nhid; /* 56 4 */
u8 priority; /* 60 1 */
u8 state; /* 61 1 */
u16 port_no; /* 62 2 */
/* --- cacheline 1 boundary (64 bytes) --- */
[...]
} __attribute__((__aligned__(8)));
When forwarding an skb via a bridge port that has VLAN tunneling
enabled, check if the backup nexthop ID stored in the bridge control
block is valid (i.e., not zero). If so, instead of attaching the
pre-allocated metadata (that only has the tunnel key set), allocate a
new metadata, set both the tunnel key and the nexthop object ID and
attach it to the skb.
By default, do not dump the new attribute to user space as a value of
zero is an invalid nexthop object ID.
The above is useful for EVPN multihoming. When one of the links
composing an Ethernet Segment (ES) fails, traffic needs to be redirected
towards the host via one of the other ES peers. For example, if a host
is multihomed to three different VTEPs, the backup port of each ES link
needs to be set to the VXLAN device and the backup nexthop ID needs to
point to an FDB nexthop group that includes the IP addresses of the
other two VTEPs. The VXLAN driver will extract the ID from the metadata
of the redirected skb, calculate its flow hash and forward it towards
one of the other VTEPs. If the ID does not exist, or represents an
invalid nexthop object, the VXLAN driver will drop the skb. This
relieves the bridge driver from the need to validate the ID.
Signed-off-by: Ido Schimmel <idosch@xxxxxxxxxx>
---
include/uapi/linux/if_link.h | 1 +
net/bridge/br_forward.c | 1 +
net/bridge/br_netlink.c | 12 ++++++++++++
net/bridge/br_private.h | 3 +++
net/bridge/br_vlan_tunnel.c | 15 +++++++++++++++
net/core/rtnetlink.c | 2 +-
6 files changed, 33 insertions(+), 1 deletion(-)
One comment below, with that fixed you can add
Acked-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 0f6a0fe09bdb..ce3117df9cec 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -570,6 +570,7 @@ enum {
IFLA_BRPORT_MCAST_N_GROUPS,
IFLA_BRPORT_MCAST_MAX_GROUPS,
IFLA_BRPORT_NEIGH_VLAN_SUPPRESS,
+ IFLA_BRPORT_BACKUP_NHID,
__IFLA_BRPORT_MAX
};
#define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
index 6116eba1bd89..9d7bc8b96b53 100644
--- a/net/bridge/br_forward.c
+++ b/net/bridge/br_forward.c
@@ -154,6 +154,7 @@ void br_forward(const struct net_bridge_port *to,
backup_port = rcu_dereference(to->backup_port);
if (unlikely(!backup_port))
goto out;
+ BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
to = backup_port;
}
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 05c5863d2e20..10f0d33d8ccf 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -211,6 +211,7 @@ static inline size_t br_port_info_size(void)
+ nla_total_size(sizeof(u8)) /* IFLA_BRPORT_MRP_IN_OPEN */
+ nla_total_size(sizeof(u32)) /* IFLA_BRPORT_MCAST_EHT_HOSTS_LIMIT */
+ nla_total_size(sizeof(u32)) /* IFLA_BRPORT_MCAST_EHT_HOSTS_CNT */
+ + nla_total_size(sizeof(u32)) /* IFLA_BRPORT_BACKUP_NHID */
+ 0;
}
@@ -319,6 +320,10 @@ static int br_port_fill_attrs(struct sk_buff *skb,
backup_p->dev->ifindex);
rcu_read_unlock();
+ if (p->backup_nhid &&
+ nla_put_u32(skb, IFLA_BRPORT_BACKUP_NHID, p->backup_nhid))
+ return -EMSGSIZE;
+
READ_ONCE(), see the comment above backup_port :)
return 0;
}
@@ -895,6 +900,7 @@ static const struct nla_policy br_port_policy[IFLA_BRPORT_MAX + 1] = {
[IFLA_BRPORT_MCAST_N_GROUPS] = { .type = NLA_REJECT },
[IFLA_BRPORT_MCAST_MAX_GROUPS] = { .type = NLA_U32 },
[IFLA_BRPORT_NEIGH_VLAN_SUPPRESS] = NLA_POLICY_MAX(NLA_U8, 1),
+ [IFLA_BRPORT_BACKUP_NHID] = { .type = NLA_U32 },
};
/* Change the state of the port and notify spanning tree */
@@ -1065,6 +1071,12 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
return err;
}
+ if (tb[IFLA_BRPORT_BACKUP_NHID]) {
+ u32 backup_nhid = nla_get_u32(tb[IFLA_BRPORT_BACKUP_NHID]);
+
+ WRITE_ONCE(p->backup_nhid, backup_nhid);
+ }
+
return 0;
}
diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index a63b32c1638e..05a965ef76f1 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -387,6 +387,7 @@ struct net_bridge_port {
struct net_bridge_vlan_group __rcu *vlgrp;
#endif
struct net_bridge_port __rcu *backup_port;
+ u32 backup_nhid;
/* STP */
u8 priority;
@@ -605,6 +606,8 @@ struct br_input_skb_cb {
*/
unsigned long fwd_hwdoms;
#endif
+
+ u32 backup_nhid;
};
#define BR_INPUT_SKB_CB(__skb) ((struct br_input_skb_cb *)(__skb)->cb)
diff --git a/net/bridge/br_vlan_tunnel.c b/net/bridge/br_vlan_tunnel.c
index 6399a8a69d07..81833ca7a2c7 100644
--- a/net/bridge/br_vlan_tunnel.c
+++ b/net/bridge/br_vlan_tunnel.c
@@ -201,6 +201,21 @@ int br_handle_egress_vlan_tunnel(struct sk_buff *skb,
if (err)
return err;
+ if (BR_INPUT_SKB_CB(skb)->backup_nhid) {
+ tunnel_dst = __ip_tun_set_dst(0, 0, 0, 0, 0, TUNNEL_KEY,
+ tunnel_id, 0);
+ if (!tunnel_dst)
+ return -ENOMEM;
+
+ tunnel_dst->u.tun_info.mode |= IP_TUNNEL_INFO_TX |
+ IP_TUNNEL_INFO_BRIDGE;
+ tunnel_dst->u.tun_info.key.nhid =
+ BR_INPUT_SKB_CB(skb)->backup_nhid;
+ skb_dst_set(skb, &tunnel_dst->dst);
+
+ return 0;
+ }
+
tunnel_dst = rcu_dereference(vlan->tinfo.tunnel_dst);
if (tunnel_dst && dst_hold_safe(&tunnel_dst->dst))
skb_dst_set(skb, &tunnel_dst->dst);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 3ad4e030846d..9e7e3377ec10 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -61,7 +61,7 @@
#include "dev.h"
#define RTNL_MAX_TYPE 50
-#define RTNL_SLAVE_MAX_TYPE 43
+#define RTNL_SLAVE_MAX_TYPE 44
struct rtnl_link {
rtnl_doit_func doit;
