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tweak NOFORK_NOEXEC.lst

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2017-08-04 16:01:39 +02:00
parent f8cdc7a2bc
commit 7f9d62d7f5
1 changed files with 11 additions and 9 deletions
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20
NOFORK_NOEXEC.lst
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@ -2,26 +2,28 @@ 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's environment - must fork
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!
"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
categories.
Why can't be NOEXEC:
suid: runs under different uid - must fork+exec
Why shouldn't be NOFORK/NOEXEC:
complex: no immediately obvious reason why NOFORK wouldn't work,
but does some non-obvoius operations (example: fuser, lsof, losetup);
nested xmallocs (typical in complex code) is a problem for NOFORK
rare: not used often enough to bother optimizing (example: poweroff)
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
daemon: runs indefinitely
complex: no immediately obvious reason why NOFORK wouldn't work,
but does some non-obvoius operations (example: fuser, lsof, losetup)
[ - NOFORK
[[ - NOFORK
@ -59,7 +61,7 @@ chpasswd - runner (list of "user:password"s from stdin)
chpst - spawner
chroot - spawner
chrt - spawner
chvt
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
@ -69,7 +71,7 @@ cp - noexec. runner
cpio - runner
crond - daemon
crontab
cryptpw
cryptpw - changes state: with --password-fd=N, moves N to stdin. Also, "rare" category. Can be noexec.
cttyhack - spawner
cut - noexec. runner
date - noexec. nofork candidate(needs to stop messing up env, free xasprintf result, not use xfuncs after xasprintf)