#!/usr/bin/env bash
 set -e
 

 EXITCODE=0
 

 # bits of this were adapted from lxc-checkconfig
 # see also https://github.com/lxc/lxc/blob/lxc-1.0.2/src/lxc/lxc-checkconfig.in
 

 possibleConfigs=(
 	'/proc/config.gz'
 	"/boot/config-$(uname -r)"
 	"/usr/src/linux-$(uname -r)/.config"
 	'/usr/src/linux/.config'
 )

 
 if [ $# -gt 0 ]; then
 	CONFIG="$1"
 else

 	: ${CONFIG:="${possibleConfigs[0]}"}

 fi

 
 if ! command -v zgrep &> /dev/null; then
 	zgrep() {
 		zcat "$2" | grep "$1"
 	}
 fi

 kernelVersion="$(uname -r)"
 kernelMajor="${kernelVersion%%.*}"
 kernelMinor="${kernelVersion#$kernelMajor.}"
 kernelMinor="${kernelMinor%%.*}"
 

 is_set() {

 	zgrep "CONFIG_$1=[y|m]" "$CONFIG" > /dev/null

 }

 is_set_in_kernel() {
 	zgrep "CONFIG_$1=y" "$CONFIG" > /dev/null
 }
 is_set_as_module() {
 	zgrep "CONFIG_$1=m" "$CONFIG" > /dev/null
 }

 
 color() {

 	local codes=()

 	if [ "$1" = 'bold' ]; then

 		codes=( "${codes[@]}" '1' )

 		shift
 	fi

 	if [ "$#" -gt 0 ]; then
 		local code=
 		case "$1" in
 			# see https://en.wikipedia.org/wiki/ANSI_escape_code#Colors
 			black) code=30 ;;
 			red) code=31 ;;
 			green) code=32 ;;
 			yellow) code=33 ;;
 			blue) code=34 ;;
 			magenta) code=35 ;;
 			cyan) code=36 ;;
 			white) code=37 ;;
 		esac
 		if [ "$code" ]; then
 			codes=( "${codes[@]}" "$code" )
 		fi

 	fi
 	local IFS=';'

 	echo -en '\033['"${codes[*]}"'m'

 }
 wrap_color() {
 	text="$1"
 	shift
 	color "$@"
 	echo -n "$text"
 	color reset
 	echo
 }
 
 wrap_good() {
 	echo "$(wrap_color "$1" white): $(wrap_color "$2" green)"
 }
 wrap_bad() {
 	echo "$(wrap_color "$1" bold): $(wrap_color "$2" bold red)"
 }
 wrap_warning() {
 	wrap_color >&2 "$*" red

 }
 
 check_flag() {

 	if is_set_in_kernel "$1"; then

 		wrap_good "CONFIG_$1" 'enabled'

 	elif is_set_as_module "$1"; then
 		wrap_good "CONFIG_$1" 'enabled (as module)'

 	else

 		wrap_bad "CONFIG_$1" 'missing'

 		EXITCODE=1

 	fi
 }
 
 check_flags() {
 	for flag in "$@"; do

 		echo -n "- "; check_flag "$flag"

 	done

 }

 check_command() {
 	if command -v "$1" >/dev/null 2>&1; then
 		wrap_good "$1 command" 'available'
 	else
 		wrap_bad "$1 command" 'missing'

 		EXITCODE=1

 	fi
 }
 
 check_device() {
 	if [ -c "$1" ]; then
 		wrap_good "$1" 'present'
 	else
 		wrap_bad "$1" 'missing'

 		EXITCODE=1

 	fi
 }
 

 check_distro_userns() {
 	source /etc/os-release 2>/dev/null || /bin/true
 	if [[ "${ID}" =~ ^(centos|rhel)$ && "${VERSION_ID}" =~ ^7 ]]; then
 		# this is a CentOS7 or RHEL7 system
 		grep -q "user_namespace.enable=1" /proc/cmdline || {
 			# no user namespace support enabled
 			wrap_bad "  (RHEL7/CentOS7" "User namespaces disabled; add 'user_namespace.enable=1' to boot command line)"

 			EXITCODE=1

 		}
 	fi
 }
 

 if [ ! -e "$CONFIG" ]; then

 	wrap_warning "warning: $CONFIG does not exist, searching other paths for kernel config ..."

 	for tryConfig in "${possibleConfigs[@]}"; do

 		if [ -e "$tryConfig" ]; then
 			CONFIG="$tryConfig"
 			break
 		fi
 	done
 	if [ ! -e "$CONFIG" ]; then
 		wrap_warning "error: cannot find kernel config"
 		wrap_warning "  try running this script again, specifying the kernel config:"

 		wrap_warning "    CONFIG=/path/to/kernel/.config $0 or $0 /path/to/kernel/.config"

 		exit 1
 	fi
 fi

 wrap_color "info: reading kernel config from $CONFIG ..." white
 echo

 
 echo 'Generally Necessary:'

 
 echo -n '- '

 cgroupSubsystemDir="$(awk '/[, ](cpu|cpuacct|cpuset|devices|freezer|memory)[, ]/ && $3 == "cgroup" { print $2 }' /proc/mounts | head -n1)"

 cgroupDir="$(dirname "$cgroupSubsystemDir")"
 if [ -d "$cgroupDir/cpu" -o -d "$cgroupDir/cpuacct" -o -d "$cgroupDir/cpuset" -o -d "$cgroupDir/devices" -o -d "$cgroupDir/freezer" -o -d "$cgroupDir/memory" ]; then

 	echo "$(wrap_good 'cgroup hierarchy' 'properly mounted') [$cgroupDir]"
 else

 	if [ "$cgroupSubsystemDir" ]; then
 		echo "$(wrap_bad 'cgroup hierarchy' 'single mountpoint!') [$cgroupSubsystemDir]"
 	else
 		echo "$(wrap_bad 'cgroup hierarchy' 'nonexistent??')"
 	fi

 	EXITCODE=1

 	echo "    $(wrap_color '(see https://github.com/tianon/cgroupfs-mount)' yellow)"
 fi
 

 if [ "$(cat /sys/module/apparmor/parameters/enabled 2>/dev/null)" = 'Y' ]; then
 	echo -n '- '
 	if command -v apparmor_parser &> /dev/null; then
 		echo "$(wrap_good 'apparmor' 'enabled and tools installed')"
 	else
 		echo "$(wrap_bad 'apparmor' 'enabled, but apparmor_parser missing')"
 		echo -n '    '
 		if command -v apt-get &> /dev/null; then
 			echo "$(wrap_color '(use "apt-get install apparmor" to fix this)')"
 		elif command -v yum &> /dev/null; then
 			echo "$(wrap_color '(your best bet is "yum install apparmor-parser")')"
 		else
 			echo "$(wrap_color '(look for an "apparmor" package for your distribution)')"
 		fi

 		EXITCODE=1

 	fi
 fi
 

 flags=(
 	NAMESPACES {NET,PID,IPC,UTS}_NS

 	CGROUPS CGROUP_CPUACCT CGROUP_DEVICE CGROUP_FREEZER CGROUP_SCHED CPUSETS MEMCG

 	KEYS

 	VETH BRIDGE BRIDGE_NETFILTER

 	NF_NAT_IPV4 IP_NF_FILTER IP_NF_TARGET_MASQUERADE

 	NETFILTER_XT_MATCH_{ADDRTYPE,CONNTRACK,IPVS}

 	IP_NF_NAT NF_NAT NF_NAT_NEEDED

 
 	# required for bind-mounting /dev/mqueue into containers
 	POSIX_MQUEUE

 )
 check_flags "${flags[@]}"

 if [ "$kernelMajor" -lt 4 ] || [ "$kernelMajor" -eq 4 -a "$kernelMinor" -lt 8 ]; then
         check_flags DEVPTS_MULTIPLE_INSTANCES
 fi
 

 echo
 
 echo 'Optional Features:'

 {

 	check_flags USER_NS

 	check_distro_userns

 }
 {

 	check_flags SECCOMP
 }
 {

 	check_flags CGROUP_PIDS
 }
 {

 	CODE=${EXITCODE}

 	check_flags MEMCG_SWAP MEMCG_SWAP_ENABLED

 	if [ -e /sys/fs/cgroup/memory/memory.memsw.limit_in_bytes ]; then
 		echo "    $(wrap_color '(cgroup swap accounting is currently enabled)' bold black)"
 		EXITCODE=${CODE}
 	elif is_set MEMCG_SWAP && ! is_set MEMCG_SWAP_ENABLED; then
 		echo "    $(wrap_color '(cgroup swap accounting is currently not enabled, you can enable it by setting boot option "swapaccount=1")' bold black)"

 	fi
 }

 {
 	if is_set LEGACY_VSYSCALL_NATIVE; then

 		echo -n "- "; wrap_bad "CONFIG_LEGACY_VSYSCALL_NATIVE" 'enabled'
 		echo "    $(wrap_color '(dangerous, provides an ASLR-bypassing target with usable ROP gadgets.)' bold black)"

 	elif is_set LEGACY_VSYSCALL_EMULATE; then
 		echo -n "- "; wrap_good "CONFIG_LEGACY_VSYSCALL_EMULATE" 'enabled'
 	elif is_set LEGACY_VSYSCALL_NONE; then
 		echo -n "- "; wrap_bad "CONFIG_LEGACY_VSYSCALL_NONE" 'enabled'
 		echo "    $(wrap_color '(containers using eglibc <= 2.13 will not work. Switch to' bold black)"
 		echo "    $(wrap_color ' "CONFIG_VSYSCALL_[NATIVE|EMULATE]" or use "vsyscall=[native|emulate]"' bold black)"
 		echo "    $(wrap_color ' on kernel command line. Note that this will disable ASLR for the,' bold black)"
 		echo "    $(wrap_color ' VDSO which may assist in exploiting security vulnerabilities.)' bold black)"
 	# else Older kernels (prior to 3dc33bd30f3e, released in v4.40-rc1) do
 	#      not have these LEGACY_VSYSCALL options and are effectively
 	#      LEGACY_VSYSCALL_EMULATE. Even older kernels are presumably
 	#      effectively LEGACY_VSYSCALL_NATIVE.
 	fi
 }

 if [ "$kernelMajor" -lt 4 ] || [ "$kernelMajor" -eq 4 -a "$kernelMinor" -le 5 ]; then
 	check_flags MEMCG_KMEM
 fi
 

 if [ "$kernelMajor" -lt 3 ] || [ "$kernelMajor" -eq 3 -a "$kernelMinor" -le 18 ]; then
 	check_flags RESOURCE_COUNTERS
 fi
 

 if [ "$kernelMajor" -lt 3 ] || [ "$kernelMajor" -eq 3 -a "$kernelMinor" -le 13 ]; then
 	netprio=NETPRIO_CGROUP
 else
 	netprio=CGROUP_NET_PRIO
 fi
 

 flags=(

 	BLK_CGROUP BLK_DEV_THROTTLING IOSCHED_CFQ CFQ_GROUP_IOSCHED

 	CGROUP_PERF

 	CGROUP_HUGETLB

 	NET_CLS_CGROUP $netprio

 	CFS_BANDWIDTH FAIR_GROUP_SCHED RT_GROUP_SCHED

 	IP_VS

 	IP_VS_NFCT
  	IP_VS_RR

 )
 check_flags "${flags[@]}"
 

 if ! is_set EXT4_USE_FOR_EXT2; then
 	check_flags EXT3_FS EXT3_FS_XATTR EXT3_FS_POSIX_ACL EXT3_FS_SECURITY
 	if ! is_set EXT3_FS || ! is_set EXT3_FS_XATTR || ! is_set EXT3_FS_POSIX_ACL || ! is_set EXT3_FS_SECURITY; then
 		echo "    $(wrap_color '(enable these ext3 configs if you are using ext3 as backing filesystem)' bold black)"
 	fi

 fi
 
 check_flags EXT4_FS EXT4_FS_POSIX_ACL EXT4_FS_SECURITY
 if ! is_set EXT4_FS || ! is_set EXT4_FS_POSIX_ACL || ! is_set EXT4_FS_SECURITY; then

 	if is_set EXT4_USE_FOR_EXT2; then
 		echo "    $(wrap_color 'enable these ext4 configs if you are using ext3 or ext4 as backing filesystem' bold black)"
 	else
 		echo "    $(wrap_color 'enable these ext4 configs if you are using ext4 as backing filesystem' bold black)"
 	fi

 fi
 

 echo '- Network Drivers:'

 echo '  - "'$(wrap_color 'overlay' blue)'":'
 check_flags VXLAN | sed 's/^/    /'
 echo '      Optional (for encrypted networks):'
 check_flags CRYPTO CRYPTO_AEAD CRYPTO_GCM CRYPTO_SEQIV CRYPTO_GHASH \
             XFRM XFRM_USER XFRM_ALGO INET_ESP INET_XFRM_MODE_TRANSPORT | sed 's/^/      /'
 echo '  - "'$(wrap_color 'ipvlan' blue)'":'
 check_flags IPVLAN | sed 's/^/    /'
 echo '  - "'$(wrap_color 'macvlan' blue)'":'
 check_flags MACVLAN DUMMY | sed 's/^/    /'

 echo '  - "'$(wrap_color 'ftp,tftp client in container' blue)'":'
 check_flags NF_NAT_FTP NF_CONNTRACK_FTP NF_NAT_TFTP NF_CONNTRACK_TFTP | sed 's/^/    /'

 
 # only fail if no storage drivers available
 CODE=${EXITCODE}
 EXITCODE=0
 STORAGE=1

 echo '- Storage Drivers:'

 echo '  - "'$(wrap_color 'aufs' blue)'":'
 check_flags AUFS_FS | sed 's/^/    /'
 if ! is_set AUFS_FS && grep -q aufs /proc/filesystems; then
 	echo "      $(wrap_color '(note that some kernels include AUFS patches but not the AUFS_FS flag)' bold black)"
 fi
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
 echo '  - "'$(wrap_color 'btrfs' blue)'":'
 check_flags BTRFS_FS | sed 's/^/    /'
 check_flags BTRFS_FS_POSIX_ACL | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
 echo '  - "'$(wrap_color 'devicemapper' blue)'":'
 check_flags BLK_DEV_DM DM_THIN_PROVISIONING | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
 echo '  - "'$(wrap_color 'overlay' blue)'":'
 check_flags OVERLAY_FS | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
 echo '  - "'$(wrap_color 'zfs' blue)'":'
 echo -n "    - "; check_device /dev/zfs
 echo -n "    - "; check_command zfs
 echo -n "    - "; check_command zpool
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
 EXITCODE=$CODE
 [ "$STORAGE" = 1 ] && EXITCODE=1

 echo
 

 check_limit_over()
 {
 	if [ $(cat "$1") -le "$2" ]; then
 		wrap_bad "- $1" "$(cat $1)"
 		wrap_color "    This should be set to at least $2, for example set: sysctl -w kernel/keys/root_maxkeys=1000000" bold black

 		EXITCODE=1

 	else
 		wrap_good "- $1" "$(cat $1)"
 	fi
 }
 
 echo 'Limits:'
 check_limit_over /proc/sys/kernel/keys/root_maxkeys 10000
 echo

 
 exit $EXITCODE