netfilter: defrag: only register defrag functionality if needed
nf_defrag modules for ipv4 and ipv6 export an empty stub function.
Any module that needs the defragmentation hooks registered simply 'calls'
this empty function to create a phony module dependency -- modprobe will
then load the defrag module too.
This extends netfilter ipv4/ipv6 defragmentation modules to delay the hook
registration until the functionality is requested within a network namespace
instead of module load time for all namespaces.
Hooks are only un-registered on module unload or when a namespace that used
such defrag functionality exits.
We have to use struct net for this as the register hooks can be called
before netns initialization here from the ipv4/ipv6 conntrack module
init path.
There is no unregister functionality support, defrag will always be
active once it was requested inside a net namespace.
The reason is that defrag has impact on nft and iptables rulesets
(without defrag we might see framents).
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
9 files changed