xtables-restore: Fix flushing referenced custom chains

The logic to replicate 'iptables-restore --noflush' behaviour of
flushing custom chains if listed in the dump was broken for chains being
referenced. A minimal dump reproducing the issue is:

| *filter
| :foobar - [0:0]
| -I INPUT -j foobar
| -A foobar -j ACCEPT
| COMMIT

With --noflush, this can be restored just once in iptables-nft-restore.
Consecutive attempts return an error since xtables tries to delete the
referenced chain and recreate it instead of performing a real flush.

Fix this by really flushing the custom chain in 'chain_user_flush'
callback and running 'chain_user_add' callback only if the chain doesn't
exist already.

Fixes: df3d92bec6007 ("xtables-compat-restore: flush user-defined chains with -n")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>

0 files changed, 0 insertions, 0 deletions