mirror of
https://github.com/slicer69/doas
synced 2024-10-01 13:43:37 +00:00
f2894542a6
I'm not claiming this script is now safe. It would certainly benefit
from additional review. I do think (and hope) that I did not make things
worse, at least.
It might be better to look at vipw(8) or visudo(8), which both are
written in C, for prior art on how to do this kind of thing securely.
Security changes:
- Exit on errors and if referencing unset variables.
- Set PATH so that we don't run unintended commands from the PATH that
is in the caller's environment.
- Set umask to prevent other users from having write access to the
temporary files.
- Use /var/tmp instead of /tmp, as /tmp is not shared between users on
all systems. (So trying to install a file from /tmp as root would not
find the file, if the user running vidoas is not root.)
XXX: Using /var/tmp does not guarantee this either, but is more likely
to work.
- Create a temporary file for editing and use ln(1) to acquire the lock.
This addresses a race condition between checking for the lock file and
creating it.
- Use "install -r" to avoid a truncated doas.conf from existing as would
happen with cp (or install without the "-r" option).
XXX: "install -r" is not portable.
- Use "install -m" to set the mode of the installed doas.conf file.
Changes to user experience:
- Don't check for executability of ${EDITOR} as it is not required to be
an absolute path to the executable.
- Don't install an unchanged doas.conf file.
- Don't install an empty doas.conf file.
- The above two checks result in a no-op in the case that ${EDITOR}
could not be run.
- Present the user with a choice of fixing errors or canceling changes.
- Output diagnostic messages to stderr (just like other tools do, e.g.
doas, ln, and cp).
TODO:
- Avoid using hard-coded paths (/usr/local/bin and /usr/local/etc).
They should be replaced with @PREFIX@/bin and @SYSCONFDIR@ before
installing.
108 lines
1.9 KiB
Bash
Executable file
108 lines
1.9 KiB
Bash
Executable file
#!/bin/sh
|
|
|
|
# This script edits a temporary copy of the doas.conf file and
|
|
# automatically checks it for syntax errors before installing
|
|
# the new copy of doas.conf.
|
|
|
|
set -eu
|
|
|
|
PATH=/bin:/usr/bin:/usr/local/bin
|
|
export PATH
|
|
|
|
PROG="${0##*/}"
|
|
|
|
umask 077
|
|
|
|
WRK_DIR=/var/tmp
|
|
INSTALL_DIR=/usr/local/etc
|
|
|
|
doas_conf_mode=0644
|
|
|
|
doas_lock_file="${WRK_DIR}/doas.conf"
|
|
installed_doas="${INSTALL_DIR}/doas.conf"
|
|
|
|
die()
|
|
{
|
|
echo "${PROG}: ${@}" 1>&2
|
|
exit 1
|
|
}
|
|
|
|
warn()
|
|
{
|
|
echo "${PROG}: ${@}" 1>&2
|
|
}
|
|
|
|
get_intr()
|
|
{
|
|
stty -a \
|
|
| sed -En '
|
|
/^(.* )?intr = / {
|
|
s///
|
|
s/;.*$//
|
|
p
|
|
}
|
|
'
|
|
}
|
|
|
|
set_trap_rm()
|
|
{
|
|
local file file_list
|
|
file_list=
|
|
for file
|
|
do
|
|
file_list="${file_list} '${file}'"
|
|
done
|
|
if [ -n "${file_list}" ]
|
|
then
|
|
trap "rm -f ${file_list}" 0 1 2 15
|
|
fi
|
|
}
|
|
|
|
tmp_doas="$(mktemp "${WRK_DIR}/doas.conf.XXXXXXXXXX")"
|
|
set_trap_rm "${tmp_doas}"
|
|
|
|
# Check to see if an existing configuration file is installed.
|
|
if [ -f "${installed_doas}" ]
|
|
then
|
|
if [ -r "${installed_doas}" ]
|
|
then
|
|
cp "${installed_doas}" "${tmp_doas}"
|
|
else
|
|
die "Cannot read ${installed_doas}"
|
|
fi
|
|
fi
|
|
|
|
# Check to see if existing temporary doas.conf file exists.
|
|
if ln "${tmp_doas}" "${doas_lock_file}"
|
|
then
|
|
set_trap_rm "${tmp_doas}" "${doas_lock_file}"
|
|
else
|
|
die "The doas.conf file is already locked"
|
|
fi
|
|
|
|
"${EDITOR:-vi}" "${tmp_doas}" || true
|
|
|
|
while ! doas -C "${tmp_doas}"
|
|
do
|
|
warn "Press enter to edit doas.conf again to fix it,"
|
|
warn "or interrupt ($(get_intr)) to cancel."
|
|
read status
|
|
"${EDITOR:-vi}" "${tmp_doas}" || true
|
|
done
|
|
|
|
if [ -s "${tmp_doas}" ]
|
|
then
|
|
if cmp -s "${tmp_doas}" "${installed_doas}"
|
|
then
|
|
warn "No changes made"
|
|
warn "${installed_doas} unchanged"
|
|
else
|
|
doas install -r -m "${doas_conf_mode}" \
|
|
"${tmp_doas}" "${installed_doas}" \
|
|
&& warn "${installed_doas} updated"
|
|
fi
|
|
else
|
|
warn "Not installing an empty doas.conf file"
|
|
warn "${installed_doas} unchanged"
|
|
fi
|