On Fri, Oct 02, 2020 at 02:28:52PM +0200, Phil Sutter wrote: > On Fri, Oct 02, 2020 at 02:15:58PM +0200, Pablo Neira Ayuso wrote: > > On Fri, Oct 02, 2020 at 02:07:32PM +0200, Phil Sutter wrote: > > > Hi, > > > > > > On Fri, Oct 02, 2020 at 01:44:36PM +0200, Arturo Borrero Gonzalez wrote: > > > > Previous to this patch, the basechain policy could not be properly configured if it wasn't > > > > explictly set when loading the ruleset, leading to iptables-nft-restore (and ip6tables-nft-restore) > > > > trying to send an invalid ruleset to the kernel. > > > > > > I fear this is not sufficient: iptables-legacy-restore leaves the > > > previous chain policy in place if '-' is given in dump file. Please try > > > this snippet from a testcase I wrote: > > > > > > $XT_MULTI iptables -P FORWARD DROP > > > > > > diff -u -Z <($XT_MULTI iptables-save | grep '^:FORWARD') \ > > > <(echo ":FORWARD DROP [0:0]") > > > > > > $XT_MULTI iptables-restore -c <<< "$TEST_RULESET" > > > diff -u -Z <($XT_MULTI iptables-save | grep '^:FORWARD') \ > > > <(echo ":FORWARD DROP [0:0]") > > > > Hm, this is how it works in this patch right? > > > > I mean, if '-' is given, chain policy attribute in the netlink message > > is not set, and the kernel sets chain policy to > > NFT_CHAIN_POLICY_UNSET. > > > > Or am I missing anything? > > This is *flushing* iptables-restore. We're dropping the chain first and > then reinstall it. OK, so this fix only works with --noflush. If --noflush is not specified, then it should be possible to extend the cache to dump the chains, get the existing policy and use it. There is now a phase to evaluate the cache requirements, so you can fetch this. Then, from the netlink phase, look up for the existing policy in the cache and use it. > Another quirk is that iptables-legacy-restore ignores the counters if > policy is '-' even if --counters flag was given. (: OK, so this needs two more fixed on top of this one.
