84 lines
3.7 KiB
Bash
Executable File
84 lines
3.7 KiB
Bash
Executable File
#!/bin/bash
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# Copyright Broadcom, Inc. All Rights Reserved.
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# SPDX-License-Identifier: APACHE-2.0
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# Copyright 2020 The Kubernetes Authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# This is a variant of the original Kubernetes iptables-wrapper below:
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# https://github.com/kubernetes-sigs/iptables-wrappers/blob/v2/iptables-wrapper-installer.sh
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# Adapted to use bash interpreter and make it compatible with read-only
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# root filesystems.
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# shellcheck disable=SC2126
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set -o errexit
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set -o nounset
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# In kubernetes 1.17 and later, kubelet will have created at least
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# one chain in the "mangle" table (either "KUBE-IPTABLES-HINT" or
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# "KUBE-KUBELET-CANARY"), so check that first, against
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# iptables-nft, because we can check that more efficiently and
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# it's more common these days.
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nft_kubelet_rules=$( (iptables-nft-save -t mangle || true; ip6tables-nft-save -t mangle || true) 2>/dev/null | grep -E '^:(KUBE-IPTABLES-HINT|KUBE-KUBELET-CANARY)' | wc -l)
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if [ "${nft_kubelet_rules}" -ne 0 ]; then
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mode=nft
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else
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# Check for kubernetes 1.17-or-later with iptables-legacy. We
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# can't pass "-t mangle" to iptables-legacy-save because it would
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# cause the kernel to create that table if it didn't already
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# exist, which we don't want. So we have to grab all the rules
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legacy_kubelet_rules=$( (iptables-legacy-save || true; ip6tables-legacy-save || true) 2>/dev/null | grep -E '^:(KUBE-IPTABLES-HINT|KUBE-KUBELET-CANARY)' | wc -l)
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if [ "${legacy_kubelet_rules}" -ne 0 ]; then
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mode=legacy
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else
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# With older kubernetes releases there may not be any _specific_
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# rules we can look for, but we assume that some non-containerized process
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# (possibly kubelet) will have created _some_ iptables rules.
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num_legacy_lines=$( (iptables-legacy-save || true; ip6tables-legacy-save || true) 2>/dev/null | grep '^-' | wc -l)
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num_nft_lines=$( (iptables-nft-save || true; ip6tables-nft-save || true) 2>/dev/null | grep '^-' | wc -l)
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if [ "${num_legacy_lines}" -gt "${num_nft_lines}" ]; then
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mode=legacy
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else
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mode=nft
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fi
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fi
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fi
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original_command="$(basename "$0")"
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# Update links to point to the selected binaries
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if [ -x /usr/sbin/alternatives ]; then
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# Fedora/SUSE style alternatives
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alternatives --set iptables "/usr/sbin/iptables-${mode}" > /dev/null || failed=1
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if [ "${failed:-0}" = 1 ]; then
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# Try the multi-binary if alternatives failed
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exec "/usr/sbin/xtables-${mode}-multi" "$original_command" "$@"
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fi
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elif [ -x /usr/sbin/update-alternatives ] || [ -x /usr/bin/update-alternatives ]; then
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# Debian style alternatives
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update-alternatives --set iptables "/usr/sbin/iptables-${mode}" > /dev/null || failed=1
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update-alternatives --set ip6tables "/usr/sbin/ip6tables-${mode}" > /dev/null || failed=1
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if [ "${failed:-0}" = 1 ]; then
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# Try the multi-binary if update-alternatives failed
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exec "/usr/sbin/xtables-${mode}-multi" "$original_command" "$@"
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fi
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else
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# Try the multi-binary
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exec "/usr/sbin/xtables-${mode}-multi" "$original_command" "$@"
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fi
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# Now re-exec the original command with the newly-selected alternative
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exec "$original_command" "$@"
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