From 633e865aec9974d560bc7b6e3e526713ed8b41e9 Mon Sep 17 00:00:00 2001 From: Ian Kelling Date: Sun, 15 Jan 2017 07:47:36 -0800 Subject: [PATCH] working version for use in systemd --- LICENSE | 202 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ README | 5 ++ newns | 150 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 357 insertions(+) create mode 100644 LICENSE create mode 100644 README create mode 100755 newns diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..d645695 --- /dev/null +++ b/LICENSE @@ -0,0 +1,202 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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Designed for use from systemd. + +[[ $EUID == 0 ]] || exec sudo -E "$BASH_SOURCE" "$@" + +cd "${BASH_SOURCE%/*}" +source ../errhandle/errcatch-function +source ../errhandle/bash-trace-function +errcatch + + +## begin arg parsing ## +action=$1 +nn=$2 # network namespace / namespace name +## end arg parsing ## + +## begin sanity checking ## + +install_error=false +if ! type -p ip &>/dev/null; then + echo "please install the iproute2 package" + install_error=true +fi +if ! type -p iptables &>/dev/null; then + echo "please install the iptables package" + install_error=true +fi +if $install_error; then + exit 1 +fi + +## end sanity checking ## + + +v0=veth0-$nn +v1=veth1-$nn +ip_base=10.173 + + +target=/run/netns/default +if [[ ! -e $target && ! -L $target ]]; then + mkdir -p /run/netns + # make the default network namespace be named + ln -s /proc/1/ns/net $target +fi + + +ipd() { ip -n default "$@"; } +dexec() { ip netns exec default "$@"; } + +# note: this script could be easily adapted to create a +# netns instead of using the systemd created one. +# ip netns add NAME +# ip -n NAME link set dev lo up + +# random note, ip netns exec creates a mount namespace and +# remaps /etc to /etc/netns/NAME. + +# head -n1 is defensive. I don't know if it's possible to have more +# than one default route. +gateway_if=$(ipd route list exact 0/0 | head -n1| sed -r 's/.*\s(\S+)\s*$/\1/') +nat() { dexec iptables -t nat $1 POSTROUTING -o $gateway_if -j MASQUERADE \ + -m comment --comment "systemd network namespace nat"; } + +find_network() { + found=false + existing=false + ips="$(ipd addr show | awk '$1 == "inet" {print $2}')" + for ((i=0; i <= 254; i++)); do + network=$ip_base.$i + if printf "%s\n" "$ips" | grep "^${network//./\\.}"; then + existing=true + else + found=true + break + fi + done +} + +start() { + + mkdir -p /root/mount_namespaces + if ! mountpoint /root/mount_namespaces >/dev/null; then + mount --bind /root/mount_namespaces /root/mount_namespaces + mount --make-private /root/mount_namespaces + fi + if [[ ! -e /root/mount_namespaces/$nn ]]; then + touch /root/mount_namespaces/$nn + fi + if ! mountpoint /root/mount_namespaces/$nn >/dev/null; then + unshare --mount=/root/mount_namespaces/$nn + fi + + + + find_network + if ! $found; then + echo "$0: error: no open network found" + exit 1 + fi + + echo 1 | dexec dd of=/proc/sys/net/ipv4/ip_forward 2>/dev/null + + _errcatch_cleanup=stop + ip link add $v0 type veth peer name $v1 + ip link set $v0 netns default + ipd addr add $network.1/24 dev $v0 + ipd link set $v0 up + nat -C &>/dev/null || nat -A + ip addr add $network.2/24 dev $v1 + ip link set $v1 up + ip route add default via $network.1 + +} + +stop() { + if ipd link list $v0 &>/dev/null; then + # this also deletes $v1 and the route we added. + ipd link del $v0 + fi + find_network + if ! $existing; then + if nat -C &>/dev/null; then nat -D; fi + fi +} + +case $action in + start|stop) + $action + ;; + *) + echo "$0: error: unsupported action" + exit 1 + ;; +esac -- 2.30.2