120 lines
3.8 KiB
Bash
120 lines
3.8 KiB
Bash
#!/hint/bash
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# SPDX-License-Identifier: GPL-2.0-only
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# shellcheck disable=SC2059 # $1 and $2 can contain the printf modifiers
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out() { printf "$1 $2\n" "${@:3}"; }
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error() { out "==> ERROR:" "$@"; } >&2
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warning() { out "==> WARNING:" "$@"; } >&2
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msg() { out "==>" "$@"; }
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die() { error "$@"; exit 1; }
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ignore_error() {
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"$@" 2>/dev/null
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return 0
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}
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chroot_add_mount() {
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mount "$@" && CHROOT_ACTIVE_MOUNTS=("$2" "${CHROOT_ACTIVE_MOUNTS[@]}")
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}
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chroot_maybe_add_mount() {
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local cond=$1; shift
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if eval "$cond"; then
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chroot_add_mount "$@"
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fi
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}
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chroot_setup() {
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CHROOT_ACTIVE_MOUNTS=()
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[[ $(trap -p EXIT) ]] && die '(BUG): attempting to overwrite existing EXIT trap'
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trap 'chroot_teardown' EXIT
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chroot_add_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
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chroot_add_mount sys "$1/sys" -t sysfs -o nosuid,noexec,nodev,ro &&
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ignore_error chroot_maybe_add_mount "[[ -d '$1/sys/firmware/efi/efivars' ]]" \
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efivarfs "$1/sys/firmware/efi/efivars" -t efivarfs -o nosuid,noexec,nodev &&
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chroot_add_mount udev "$1/dev" -t devtmpfs -o mode=0755,nosuid &&
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chroot_add_mount devpts "$1/dev/pts" -t devpts -o mode=0620,gid=5,nosuid,noexec &&
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chroot_add_mount shm "$1/dev/shm" -t tmpfs -o mode=1777,nosuid,nodev &&
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chroot_add_mount /run "$1/run" --bind --make-private &&
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chroot_add_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
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}
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chroot_teardown() {
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if (( ${#CHROOT_ACTIVE_MOUNTS[@]} )); then
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umount "${CHROOT_ACTIVE_MOUNTS[@]}"
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fi
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unset CHROOT_ACTIVE_MOUNTS
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}
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chroot_add_mount_lazy() {
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mount "$@" && CHROOT_ACTIVE_LAZY=("$2" "${CHROOT_ACTIVE_LAZY[@]}")
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}
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chroot_bind_device() {
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touch "$2" && CHROOT_ACTIVE_FILES=("$2" "${CHROOT_ACTIVE_FILES[@]}")
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chroot_add_mount "$1" "$2" --bind
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}
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chroot_add_link() {
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ln -sf "$1" "$2" && CHROOT_ACTIVE_FILES=("$2" "${CHROOT_ACTIVE_FILES[@]}")
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}
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unshare_setup() {
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CHROOT_ACTIVE_MOUNTS=()
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CHROOT_ACTIVE_LAZY=()
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CHROOT_ACTIVE_FILES=()
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[[ $(trap -p EXIT) ]] && die '(BUG): attempting to overwrite existing EXIT trap'
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trap 'unshare_teardown' EXIT
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chroot_add_mount_lazy "$1" "$1" --bind &&
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chroot_add_mount proc "$1/proc" -t proc -o nosuid,noexec,nodev &&
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chroot_add_mount_lazy /sys "$1/sys" --rbind &&
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chroot_add_link /proc/self/fd "$1/dev/fd" &&
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chroot_add_link /proc/self/fd/0 "$1/dev/stdin" &&
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chroot_add_link /proc/self/fd/1 "$1/dev/stdout" &&
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chroot_add_link /proc/self/fd/2 "$1/dev/stderr" &&
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chroot_bind_device /dev/full "$1/dev/full" &&
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chroot_bind_device /dev/null "$1/dev/null" &&
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chroot_bind_device /dev/random "$1/dev/random" &&
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chroot_bind_device /dev/tty "$1/dev/tty" &&
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chroot_bind_device /dev/urandom "$1/dev/urandom" &&
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chroot_bind_device /dev/zero "$1/dev/zero" &&
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chroot_add_mount run "$1/run" -t tmpfs -o nosuid,nodev,mode=0755 &&
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chroot_add_mount tmp "$1/tmp" -t tmpfs -o mode=1777,strictatime,nodev,nosuid
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}
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unshare_teardown() {
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chroot_teardown
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if (( ${#CHROOT_ACTIVE_LAZY[@]} )); then
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umount --lazy "${CHROOT_ACTIVE_LAZY[@]}"
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fi
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unset CHROOT_ACTIVE_LAZY
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if (( ${#CHROOT_ACTIVE_FILES[@]} )); then
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rm "${CHROOT_ACTIVE_FILES[@]}"
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fi
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unset CHROOT_ACTIVE_FILES
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}
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pid_unshare="unshare --fork --pid"
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mount_unshare="$pid_unshare --mount --map-auto --map-root-user --setuid 0 --setgid 0"
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# This outputs code for declaring all variables to stdout. For example, if
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# FOO=BAR, then running
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# declare -p FOO
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# will result in the output
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# declare -- FOO="bar"
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# This function may be used to re-declare all currently used variables and
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# functions in a new shell.
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declare_all() {
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# Remove read-only variables to avoid warnings. Unfortunately, declare +r -p
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# doesn't work like it looks like it should (declaring only read-write
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# variables). However, declare -rp will print out read-only variables, which
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# we can then use to remove those definitions.
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declare -p | grep -Fvf <(declare -rp)
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# Then declare functions
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declare -pf
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}
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