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#!/usr/bin/env bash
# shellcheck disable=SC1117
# cgroup-network-helper.sh
# detect container and virtual machine interfaces
#
# (C) 2017 Costa Tsaousis
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This script is called as root (by cgroup-network), with either a pid, or a cgroup path.
# It tries to find all the network interfaces that belong to the same cgroup.
#
# It supports several method for this detection:
#
# 1. cgroup-network (the binary father of this script) detects veth network interfaces,
# by examining iflink and ifindex IDs and switching namespaces
# (it also detects the interface name as it is used by the container).
#
# 2. this script, uses /proc/PID/fdinfo to find tun/tap network interfaces.
#
# 3. this script, calls virsh to find libvirt network interfaces.
#
# -----------------------------------------------------------------------------
# the system path is cleared by cgroup-network
# shellcheck source=/dev/null
[ -f /etc/profile ] && source /etc/profile
export LC_ALL=C
PROGRAM_NAME="$(basename "${0}")"
logdate() {
date "+%Y-%m-%d %H:%M:%S"
}
log() {
local status="${1}"
shift
echo >&2 "$(logdate): ${PROGRAM_NAME}: ${status}: ${*}"
}
warning() {
log WARNING "${@}"
}
error() {
log ERROR "${@}"
}
info() {
log INFO "${@}"
}
fatal() {
log FATAL "${@}"
exit 1
}
debug=${NETDATA_CGROUP_NETWORK_HELPER_DEBUG=0}
debug() {
[ "${debug}" = "1" ] && log DEBUG "${@}"
}
# -----------------------------------------------------------------------------
# check for BASH v4+ (required for associative arrays)
[ $(( BASH_VERSINFO[0] )) -lt 4 ] && \
fatal "BASH version 4 or later is required (this is ${BASH_VERSION})."
# -----------------------------------------------------------------------------
# parse the arguments
pid=
cgroup=
while [ ! -z "${1}" ]
do
case "${1}" in
--cgroup) cgroup="${2}"; shift 1;;
--pid|-p) pid="${2}"; shift 1;;
--debug|debug) debug=1;;
*) fatal "Cannot understand argument '${1}'";;
esac
shift
done
if [ -z "${pid}" ] && [ -z "${cgroup}" ]
then
fatal "Either --pid or --cgroup is required"
fi
# -----------------------------------------------------------------------------
set_source() {
[ ${debug} -eq 1 ] && echo "SRC ${*}"
}
# -----------------------------------------------------------------------------
# veth interfaces via cgroup
# cgroup-network can detect veth interfaces by itself (written in C).
# If you seek for a shell version of what it does, check this:
# https://github.com/netdata/netdata/issues/474#issuecomment-317866709
# -----------------------------------------------------------------------------
# tun/tap interfaces via /proc/PID/fdinfo
# find any tun/tap devices linked to a pid
proc_pid_fdinfo_iff() {
local p="${1}" # the pid
debug "Searching for tun/tap interfaces for pid ${p}..."
set_source "fdinfo"
grep "^iff:.*" "${NETDATA_HOST_PREFIX}/proc/${p}/fdinfo"/* 2>/dev/null | cut -f 2
}
find_tun_tap_interfaces_for_cgroup() {
local c="${1}" # the cgroup path
# for each pid of the cgroup
# find any tun/tap devices linked to the pid
if [ -f "${c}/emulator/cgroup.procs" ]
then
local p
for p in $(< "${c}/emulator/cgroup.procs" )
do
proc_pid_fdinfo_iff "${p}"
done
else
debug "Cannot find file '${c}/emulator/cgroup.procs', not searching for tun/tap interfaces."
fi
}
# -----------------------------------------------------------------------------
# virsh domain network interfaces
virsh_cgroup_to_domain_name() {
local c="${1}" # the cgroup path
debug "extracting a possible virsh domain from cgroup ${c}..."
# extract for the cgroup path
sed -n -e "s|.*/machine-qemu\\\\x2d[0-9]\+\\\\x2d\(.*\)\.scope$|\1|p" \
-e "s|.*/machine/\(.*\)\.libvirt-qemu$|\1|p" \
<<EOF
${c}
EOF
}
virsh_find_all_interfaces_for_cgroup() {
local c="${1}" # the cgroup path
# the virsh command
local virsh
# shellcheck disable=SC2230
virsh="$(which virsh 2>/dev/null || command -v virsh 2>/dev/null)"
if [ ! -z "${virsh}" ]
then
local d
d="$(virsh_cgroup_to_domain_name "${c}")"
if [ ! -z "${d}" ]
then
debug "running: virsh domiflist ${d}; to find the network interfaces"
# match only 'network' interfaces from virsh output
set_source "virsh"
"${virsh}" -r domiflist "${d}" |\
sed -n \
-e "s|^\([^[:space:]]\+\)[[:space:]]\+network[[:space:]]\+\([^[:space:]]\+\)[[:space:]]\+[^[:space:]]\+[[:space:]]\+[^[:space:]]\+$|\1 \1_\2|p" \
-e "s|^\([^[:space:]]\+\)[[:space:]]\+bridge[[:space:]]\+\([^[:space:]]\+\)[[:space:]]\+[^[:space:]]\+[[:space:]]\+[^[:space:]]\+$|\1 \1_\2|p"
else
debug "no virsh domain extracted from cgroup ${c}"
fi
else
debug "virsh command is not available"
fi
}
# -----------------------------------------------------------------------------
# netnsid detected interfaces
netnsid_find_all_interfaces_for_pid() {
local pid="${1}"
[ -z "${pid}" ] && return 1
local nsid=$(lsns -t net -p ${pid} -o NETNSID -nr)
[ -z "${nsid}" -o "${nsid}" = "unassigned" ] && return 1
set_source "netnsid"
ip link show |\
grep -B 1 -E " link-netnsid ${nsid}($| )" |\
ip link show | grep -B 1 -E " link-netnsid ${nsid}($| )" | sed -n -e "s|^[[:space:]]*[0-9]\+:[[:space:]]\+\([A-Za-z0-9_]\+\)\(@[A-Za-z0-9_]\+\)*:[[:space:]].*$|\1|p"
}
netnsid_find_all_interfaces_for_cgroup() {
local c="${1}" # the cgroup path
# for each pid of the cgroup
# find any tun/tap devices linked to the pid
if [ -f "${c}/cgroup.procs" ]
then
local p
for p in $(< "${c}/cgroup.procs" )
do
netnsid_find_all_interfaces_for_pid "${p}"
done
else
debug "Cannot find file '${c}/cgroup.procs', not searching for netnsid interfaces."
fi
}
# -----------------------------------------------------------------------------
find_all_interfaces_of_pid_or_cgroup() {
local p="${1}" c="${2}" # the pid and the cgroup path
if [ ! -z "${pid}" ]
then
# we have been called with a pid
proc_pid_fdinfo_iff "${p}"
netnsid_find_all_interfaces_for_pid "${p}"
elif [ ! -z "${c}" ]
then
# we have been called with a cgroup
info "searching for network interfaces of cgroup '${c}'"
find_tun_tap_interfaces_for_cgroup "${c}"
virsh_find_all_interfaces_for_cgroup "${c}"
netnsid_find_all_interfaces_for_cgroup "${c}"
else
error "Either a pid or a cgroup path is needed"
return 1
fi
return 0
}
# -----------------------------------------------------------------------------
# an associative array to store the interfaces
# the index is the interface name as seen by the host
# the value is the interface name as seen by the guest / container
declare -A devs=()
# store all interfaces found in the associative array
# this will also give the unique devices, as seen by the host
last_src=
# shellcheck disable=SC2162
while read host_device guest_device
do
[ -z "${host_device}" ] && continue
[ "${host_device}" = "SRC" ] && last_src="${guest_device}" && continue
# the default guest_device is the host_device
[ -z "${guest_device}" ] && guest_device="${host_device}"
# when we run in debug, show the source
debug "Found host device '${host_device}', guest device '${guest_device}', detected via '${last_src}'"
if [ -z "${devs[${host_device}]}" ] || [ "${devs[${host_device}]}" = "${host_device}" ]; then
devs[${host_device}]="${guest_device}"
fi
done < <( find_all_interfaces_of_pid_or_cgroup "${pid}" "${cgroup}" )
# print the interfaces found, in the format netdata expects them
found=0
for x in "${!devs[@]}"
do
found=$((found + 1))
echo "${x} ${devs[${x}]}"
done
debug "found ${found} network interfaces for pid '${pid}', cgroup '${cgroup}', run as ${USER}, ${UID}"
# let netdata know if we found any
[ ${found} -eq 0 ] && exit 1
exit 0
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