Hangbin Liu <liuhangbin@xxxxxxxxx> wrote:
>When validation on the backup slave is enabled, we need to validate the
>Neighbor Solicitation (NS) messages received on the backup slave. To
>receive these messages, the correct destination MAC address must be added
>to the slave. However, the target in bonding is a unicast address, which
>we cannot use directly. Instead, we should first convert it to a
>Solicited-Node Multicast Address and then derive the corresponding MAC
>address.
>
>Fixes: 8eb36164d1a6 ("bonding: add ns target multicast address to slave device")
>Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
I think this now deserves some commentary in the code. Not
because this function itself is unclear, but because there's the
similarly-named slave_set_ns_maddr() (singular, not plural as in this
patch) that will behave in a subtly different manner after this patch is
applied.
The "maddrs" version here will convert the provided IPv6 address
to the IPv6 solicited-nodes multicast address (RFC 4291 section 2.7.1)
and thence to the MAC address, via ndisc_mc_map(), whereas the "maddr"
version uses the supplied IPv6 address directly for multicast MAC
address conversion.
Assuming that I'm following that correctly, I think this
distinction deserves explanation. And if I'm getting it wrong, then it
definitely deserves some explanation.
FWIW, functionally, I think it's doing the correct thing.
-J
>---
> drivers/net/bonding/bond_options.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/net/bonding/bond_options.c b/drivers/net/bonding/bond_options.c
>index 327b6ecdc77e..63cf209dcdc9 100644
>--- a/drivers/net/bonding/bond_options.c
>+++ b/drivers/net/bonding/bond_options.c
>@@ -1246,6 +1246,7 @@ static void slave_set_ns_maddrs(struct bonding *bond, struct slave *slave, bool
> {
> struct in6_addr *targets = bond->params.ns_targets;
> char slot_maddr[MAX_ADDR_LEN];
>+ struct in6_addr mcaddr;
> int i;
>
> if (!slave_can_set_ns_maddr(bond, slave))
>@@ -1255,7 +1256,8 @@ static void slave_set_ns_maddrs(struct bonding *bond, struct slave *slave, bool
> if (ipv6_addr_any(&targets[i]))
> break;
>
>- if (!ndisc_mc_map(&targets[i], slot_maddr, slave->dev, 0)) {
>+ addrconf_addr_solict_mult(&targets[i], &mcaddr);
>+ if (!ndisc_mc_map(&mcaddr, slot_maddr, slave->dev, 0)) {
> if (add)
> dev_mc_add(slave->dev, slot_maddr);
> else
>--
>2.46.0
>
---
-Jay Vosburgh, jv@xxxxxxxxxxxxx
