in nftables, 'meter' can be used to instantiate a hash-table at run
time:
rule add filter forward iif "internal" meter hostacct { ip saddr counter}
nft list meter ip filter hostacct
table ip filter {
meter hostacct {
type ipv4_addr
elements = { 192.168.0.1 : counter packets 8 bytes 2672, ..
because elemets get added on the fly, the kernel must chose a set
backend type that implements the ->update() function, otherwise
rule insertion fails with EOPNOTSUPP.
Therefore, skip set types that lack ->update, and also
make sure we do not discard a (bad) candidate when we did yet
find any candidate at all. This could happen when userspace prefers
low memory footprint -- the set implementation currently checked might
not be a fit at all. Make sure we pick it anyway (!bops). In
case next candidate is a better fix, it will be chosen instead.
But in case nothing else is found we at least have a non-ideal
match rather than no match at all.
Fixes: 6c03ae210c ("netfilter: nft_set_hash: add non-resizable hashtable implementation")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
4f2921ca21