busybox/NOFORK_NOEXEC.lst

Why an applet can't be NOFORK or NOEXEC?

Why can't be NOFORK:
interactive: may wait for user input, ^C has to work
spawner: "tool PROG ARGS" which changes program state and execs - must fork
changes state: e.g. environment, signal handlers
alloc+xfunc: xmalloc, then xfunc - leaks memory if xfunc dies
open+xfunc: opens fd, then calls xfunc - fd is leaked if xfunc dies
leaks: does not free allocated memory or opened fds
runner: sometimes may run for long(ish) time, and/or works with network:
	^C has to work (cat BIGFILE, chmod -R, ftpget, nc)

"runners" can become eligible after shell is taught ^C to interrupt NOFORKs,
need to be inspected that they do not fall into alloc+xfunc, open+xfunc,
leak categories.

Why can't be NOEXEC:
suid: runs under different uid - must fork+exec

Why shouldn't be NOFORK/NOEXEC:
rare: not started often enough to bother optimizing (example: poweroff)
daemon: runs indefinitely; these are also always fit "rare" category
longterm: often runs for a long time (many seconds), execing would make
	memory footprint smaller
complex: no immediately obvious reason why NOFORK wouldn't work,
	but does some non-obvoius operations (example: fuser, lsof, losetup);
	detailed audit often turns out that it's a leaker

Interesting example of "interactive" applet which is nevertheless can be
(and is) NOEXEC is "rm". Yes, "rm -i" is interactive - but it's not that typical
for users to keep it waiting for many minutes, whereas running "rm" in shell
is very typical, and speeding up this common use via NOEXEC is useful.
IOW: rm is "interactive", but not "longterm".


[ - NOFORK
[[ - NOFORK
acpid - daemon
add-shell
addgroup
adduser
adjtimex
ar - runner
arch - NOFORK
arp - complex, rare
arping - runner
ash - interactive, longterm
awk - noexec. runner
base64 - runner
basename - NOFORK
beep
blkdiscard
blkid
blockdev
bootchartd - daemon
brctl
bunzip2 - runner
busybox
bzcat - runner
bzip2 - runner
cal - runner: cal -n9999
cat - runner
chat - needs ^C to work
chattr - runner
chgrp - noexec. runner
chmod - noexec. runner
chown - noexec. runner
chpasswd - runner (list of "user:password"s from stdin)
chpst - noexec candidate, spawner
chroot - noexec candidate, spawner
chrt - noexec candidate, spawner
chvt - leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds. Also, "rare" category. Can be noexec.
cksum - noexec. runner
clear - NOFORK
cmp - runner
comm - runner
conspy - interactive, longterm
cp - noexec. runner
cpio - runner
crond - daemon
crontab
cryptpw - changes state: with --password-fd=N, moves N to stdin. Also, "rare" category. Can be noexec.
cttyhack - noexec candidate, spawner
cut - noexec. runner
date - noexec. nofork candidate(needs to stop messing up env, free xasprintf result, not use xfuncs after xasprintf)
dc - runner (eats stdin if no params)
dd - noexec. runner
deallocvt - leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds. Also, "rare" category. Can be noexec.
delgroup
deluser
depmod - complex, rare
devmem - runner, complex (access to device memory may hang)
df - leaks: nested allocs
dhcprelay - daemon
diff - runner
dirname - NOFORK
dmesg - runner
dnsd - daemon
dnsdomainname - needs ^C (may talk to DNS servers, which may be down)
dos2unix - noexec. runner
dpkg - runner
du - runner
dumpkmap - leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds. Also, "rare" category. Can be noexec.
dumpleases
echo - NOFORK
ed - interactive, longterm
egrep - longterm runner ("CMD | egrep ..."  may run indefinitely, better to exec to conserve memory)
eject - leaks: open+ioctl_or_perror_and_die, changes state (moves fds)
env - noexec. spawner, changes state (env)
envdir - noexec candidate, spawner
envuidgid - noexec candidate, spawner
expand - runner
expr - leaks: nested allocs
factor - runner (eats stdin if no params)
fakeidentd - daemon
false - NOFORK
fatattr - leaks: open+xioctl, complex
fbset - leaks: open+xfunc, complex, rare
fbsplash - runner, longterm
fdflush - leaks: open+ioctl_or_perror_and_die, needs ^C (floppy may be unresponsive), rare
fdformat - needs ^C (floppy may be unresponsive), longterm, rare
fdisk - interactive, longterm
fgconsole - leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds. Also, "rare" category. Can be noexec.
fgrep - longterm runner ("CMD | fgrep ..."  may run indefinitely, better to exec to conserve memory)
find - noexec. runner
findfs - suid
flash_eraseall
flash_lock
flash_unlock
flashcp
flock - spawner, changes state (file locks)
fold - noexec. runner
free - nofork candidate(struct globals, needs to close /proc/meminfo fd)
freeramdisk - leaks: open+ioctl_or_perror_and_die
fsck - interactive, longterm
fsck.minix
fsfreeze - noexec candidate (it's very simple), leaks: open+xioctl
fstrim - noexec candidate (it's very simple), leaks: open+xioctl
fsync - NOFORK
ftpd - daemon
ftpget - runner
ftpput - runner
fuser - complex
getopt - noexec. leaks: many allocs
getty - interactive, longterm
grep - longterm runner ("CMD | grep ..."  may run indefinitely, better to exec to conserve memory)
groups - noexec
gunzip - runner
gzip - runner
halt - rare
hd - noexec. runner
hdparm - complex, rare
head - noexec. runner
hexdump - noexec. runner
hostid - NOFORK
hostname - DNS resolution may trigger, need ^C
httpd - daemon
hush - interactive, longterm
hwclock - talks to hardware (xioctl(RTC_RD_TIME)) - needs ^C
i2cdetect
i2cdump
i2cget
i2cset
id - noexec
ifconfig
ifenslave
ifplugd - daemon
inetd - daemon
init - daemon
inotifyd - daemon
insmod - noexec
install - runner
ionice - spawner
iostat - runner
ip - noexec candidate
ipaddr - noexec candidate
ipcalc - noexec candidate
ipcrm - noexec candidate
ipcs - noexec candidate
iplink - noexec candidate
ipneigh - noexec candidate
iproute - noexec candidate
iprule - noexec candidate
iptunnel - noexec candidate
kbd_mode
kill - NOFORK
killall - NOFORK
killall5 - NOFORK
klogd - daemon
last - runner (I've got 1300 lines of output when tried it)
less - interactive, longterm
link - NOFORK
linux32 - spawner
linux64 - spawner
linuxrc - daemon
ln - noexec
loadfont
loadkmap - leaks: get_console_fd_or_die() may open a new fd, or return one of stdio fds. Also, "rare" category. Can be noexec.
logger - runner
login - suid, interactive, longterm
logname - NOFORK
losetup - complex
lpd - daemon
lpq - runner
lpr - runner
ls - noexec. runner
lsattr - runner. noexec candidate (ls is, why not this one?)
lsmod - noexec
lsof - complex
lspci - noexec candidate, too rare to bother for nofork
lsscsi - noexec candidate, too rare to bother for nofork
lsusb - noexec candidate, too rare to bother for nofork
lzcat - runner
lzma - runner
lzop - runner
lzopcat - runner
makedevs
makemime - runner
man - spawner, interactive, longterm
md5sum - noexec. runner
mdev - daemon
mesg
microcom - interactive, longterm
mkdir - NOFORK
mkdosfs
mke2fs
mkfifo - noexec
mkfs.ext2
mkfs.minix
mkfs.vfat
mknod - noexec
mkpasswd
mkswap
mktemp - noexec. leaks: xstrdup+concat_path_file
modinfo - noexec
modprobe - noexec
more - interactive, longterm
mount - suid
mountpoint
mpstat
mt
mv - runner (can be noexec?)
nameif
nbd-client
nc - runner
netstat - runner with -c
nice - spawner
nl - runner
nmeter - runner
nohup - spawner
nproc - NOFORK
ntpd - daemon
od - runner
openvt - spawner
partprobe
passwd - suid
paste - noexec. runner
patch
pgrep - nofork candidate(xregcomp, procps_scan - are they ok?)
pidof - nofork candidate(uses find_pid_by_name, is that ok?)
ping - suid, runner
ping6 - suid, runner
pipe_progress
pivot_root
pkill - nofork candidate(xregcomp, procps_scan - are they ok?)
pmap
popmaildir - runner
poweroff - rare
powertop - interactive, longterm
printenv - NOFORK
printf - NOFORK
ps - noexec candidate
pscan - longterm
pstree
pwd - NOFORK
pwdx - NOFORK
raidautorun
rdate
rdev
readlink - NOFORK
readprofile
realpath - NOFORK
reboot - rare
reformime - runner
remove-shell
renice - nofork candidate(uses getpwnam, is that ok?)
reset - spawner (execs "stty")
resize - noexec. changes state (signal handlers)
rev - runner
rm - noexec. rm -i interactive
rmdir - NOFORK
rmmod - noexec
route
rpm - runner
rpm2cpio - runner
rtcwake - puts system to sleep, optimizing this for speed is pointless
run-parts
runlevel - noexec. can be nofork if "endutxent()" is called unconditionally, but too rare to bother?
runsv - daemon
runsvdir - daemon
rx - runner
script
scriptreplay
sed - runner
sendmail - runner
seq - noexec. runner
setarch - spawner
setconsole
setfont
setkeycodes
setlogcons
setpriv - spawner
setserial
setsid - spawner
setuidgid
sha1sum - noexec. runner
sha256sum - noexec. runner
sha3sum - noexec. runner
sha512sum - noexec. runner
showkey - interactive, longterm
shred - runner
shuf - noexec. runner
slattach
sleep - runner
smemcap - runner
softlimit - spawner
sort - noexec. runner
split - runner
ssl_client - network
start-stop-daemon
stat - nofork candidate(needs fewer allocs)
strings - runner
stty
su - suid, spawner
sulogin - spawner
sum - runner
sv
svc
svlogd - daemon
swapoff - rare
swapon - rare
switch_root - spawner, rare, changes state
sync - NOFORK
sysctl
syslogd - daemon
tac - noexec. runner
tail - runner
tar - runner
taskset - spawner
tcpsvd - daemon
tee - runner
telnet - interactive, longterm
telnetd - daemon
test - NOFORK
tftp - runner
tftpd - daemon
time - spawner, changes state (signals)
timeout - spawner, changes state (signals)
top - interactive, longterm
touch - NOFORK
tr - runner
traceroute - suid, runner
traceroute6 - suid, runner
true - NOFORK
truncate - NOFORK
tty - NOFORK
ttysize - NOFORK
tunctl
tune2fs - leaks: open+xfunc
ubiattach
ubidetach
ubimkvol
ubirename
ubirmvol
ubirsvol
ubiupdatevol
udhcpc - daemon
udhcpd - daemon
udpsvd - daemon
uevent - daemon
umount
uname - NOFORK
uncompress - runner
unexpand - runner
uniq - runner
unix2dos - noexec. runner
unlink - NOFORK
unlzma - runner
unlzop - runner
unxz - runner
unzip - runner
uptime - nofork candidate(is getutxent ok?)
users - nofork candidate(is getutxent ok?)
usleep - NOFORK
uudecode - runner
uuencode - runner
vconfig - leaks: xsocket+ioctl_or_perror_and_die
vi - interactive, longterm
vlock - suid
volname - runner
w
wall - suid
watch - longterm
watchdog - daemon
wc - runner
wget - longterm
which - NOFORK
who
whoami - NOFORK
whois
xargs - noexec. spawner
xxd - noexec. runner
xz - runner
xzcat - runner
yes - noexec. runner
zcat - runner
zcip - daemon