vxlan: vnifilter: validate the VXLAN_VNIFILTER_ENTRY nest

vxlan_vnifilter_process() parses the message with vni_filter_policy,
whose VXLAN_VNIFILTER_ENTRY is a bare NLA_NESTED with no nested policy
attached. The entry attributes are therefore validated only later, one
entry at a time, by the nla_parse_nested() inside
vxlan_process_vni_filter(). Entries are parsed as they are dispatched:
in a message whose first entry is valid and whose second is not, the
first entry is applied and its RTM_NEWTUNNEL notification sent before
the second is rejected.

Link the nest to vni_filter_entry_policy with NLA_POLICY_NESTED() so
every entry is checked against the entry policy up front, before any
entry is acted on. A message whose entry the policy rejects -- a
malformed attribute, or, with the next patch, an out-of-range endpoint
-- is now refused as a unit and installs nothing. Faults the policy does
not cover, such as a device or handler error raised on a later entry,
are unchanged: entries are still dispatched and applied one at a time.

This reorders two faults. The nest is validated before the device is
looked up and before the vnifilter flag is checked, so a request
rejected by the entry policy, aimed at a missing or non-vnifilter
device, now returns that policy error where it previously returned
-ENODEV or -EOPNOTSUPP. The request was invalid either way; only the
errno an operator sees changes.

The nla_parse_nested() in vxlan_process_vni_filter() stays: it is what
fills the per-entry attribute table the handler reads. It can no longer
fail on a message that has reached it.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/netdev/20260921150904.65a704eb@kernel.org/
Signed-off-by: Ali Firas <alishmery18@gmail.com>
Link: https://patch.msgid.link/20261014123814.388557-2-alishmery18@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions