xtables-compat: fix ipv4 frag (-f)

iptables-translate -A I -f
nft add rule ip filter I ip frag-off != 0 counter

iptables however checks:
frag_off = ntohs(iph->frag_off) & IP_OFFSET;

if (NF_INVF(ipinfo, IPT_INV_FRAG,
    (ipinfo->flags & IPT_F_FRAG) && !frag_off))
       return false;

So we need to mask off non-offset bits.

Second issue is that we negated the meaning in ipt-restore.

-f should match if (frag_off & IP_OFFSET) NE 0
  ! -f matches non-fragmented packets, i.e.
  frag_off & IP_OFFSET == 0.

So we cannot use nft_invflags2cmp(), as that will use
NEQ for negation, but we need EQ instead here.

Signed-off-by: Florian Westphal <fw@strlen.de>

0 files changed, 0 insertions, 0 deletions