nft: Fix for ruleset flush while restoring

If ruleset is flushed while an instance of iptables-nft-restore is
running and has seen a COMMIT line once, it doesn't notice the
disappeared table while handling the next COMMIT. This is due to table
existence being tracked via 'initialized' boolean which is only reset
by nft_table_flush().

To fix this, drop the dedicated 'initialized' boolean and switch users
to the recently introduced 'exists' one.

As a side-effect, this causes base chain existence being checked for
each command calling nft_xt_builtin_init() as the old 'initialized' bit
was used to track if that function has been called before or not.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/iptables/tests/shell/testcases/nft-only/0007-mid-restore-flush_0 b/iptables/tests/shell/testcases/nft-only/0007-mid-restore-flush_0
new file mode 100755
index 00000000..43880ffb
--- /dev/null
+++ b/iptables/tests/shell/testcases/nft-only/0007-mid-restore-flush_0
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+[[ $XT_MULTI == *xtables-nft-multi ]] || { echo "skip $XT_MULTI"; exit 0; }
+nft -v >/dev/null || { echo "skip $XT_MULTI (no nft)"; exit 0; }
+
+coproc $XT_MULTI iptables-restore --noflush
+
+cat >&"${COPROC[1]}" <<EOF
+*filter
+:foo [0:0]
+COMMIT
+*filter
+:foo [0:0]
+EOF
+
+$XT_MULTI iptables-save | grep -q ':foo'
+nft flush ruleset
+
+echo "COMMIT" >&"${COPROC[1]}"
+sleep 1
+
+[[ -n $COPROC_PID ]] && kill $COPROC_PID
+wait