Merge pull request #93 from kisslinux/ezupdate2

kiss: Reverse permissions model (simpler method)
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dylan 2020-01-28 00:51:01 +02:00 committed by GitHub
commit 44e983b95d
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2 changed files with 160 additions and 43 deletions

7
.editorconfig Normal file
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@ -0,0 +1,7 @@
root = true
# Force GitHub to display tabs
# mixed with [4] spaces properly.
[kiss]
indent_style = tab
indent_size = 4

196
kiss
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@ -45,6 +45,106 @@ prompt() {
read -r _
}
root_cache() {
# This function simply mimics a 'su' prompt to then store
# the root password for the lifetime of the package manager.
#
# This function is called once when needed to cache the
# password. The password is not accessible to any subprocesses
# and should never leave the package manager's process.
#
# This behavior is needed as there is no POSIX shell method
# of running a shell function as a different user. We can't
# selectively lower or raise permissions in a seamless way
# through "normal" means.
#
# Root is only needed when installing/removing packages whereas
# non-root permissions are needed in countless places throughout.
#
# This is the only *workable* solution to 1) not run the entire
# package manager as root and 2) avoid prompting for password
# before, during and after builds numerous times.
#
# NOTE: Careful consideration has been taken in regards to this
# change and I would have loved an inconspicuous solution
# to this problem... but it doesn't exist.
#
# This change was needed as the existing behavior was not ideal
# in any way and needed to be fixed.
printf 'Password: '
# Disable echoing to the terminal while the password is inputted
# by the user. The below commands read from '/dev/tty' to ensure
# they work when run from a subshell.
#
# The variable '$cached' is used to check if we've been here
# before. We cannot check whether or not '$pass' is empty as the
# '[' command may be external which would result in /proc leakage.
stty -F /dev/tty -echo
IFS= read -r pass < /dev/tty && cached=1
stty -F /dev/tty echo
printf '\n'
# Validate the password now with a simple 'true' command as we
# don't yet need to elevate permissions.
dosu /bin/true
}
dosu() {
[ "$cached" ] || root_cache
# Declare this as a function to avoid repeating it twice
# below. Great naming of functions all around.
#
# Run a command as root using the cached password. The 'su'
# command allows you to input a password via stdin. To hide
# the prompt, the command's output is sent to '/dev/tty'
# and the output of 'su' is sent to '/dev/null'.
dosudo() { su "${drop_to:-root}" -c "$* >/dev/tty" >/dev/null; }
# The code below uses the most secure method of sending
# data over stdin based on what is available in the system.
#
# The great debate: Use a heredoc or echo+pipe for password
# input over stdin? Time to explain.
#
# 1) 'printf | cmd' is the most secure IF 'printf' is built
# into the shell and NOT an external command. When 'printf'
# is external, the password WILL be leaked over '/proc'.
#
# Safe shells here are anything with a builtin 'printf',
# 'ash', 'dash', 'bash' and most other shells.
#
# 2) Using a heredoc is as secure as the above method (when
# builtin) IF and only IF the user's shell implements
# heredocs WITHOUT the use of temporary files (See bash!).
#
# When using heredocs and a temporary file the risk is a
# tiny window in which the input is available inside of
# a temporary file.
#
# 'ash' and 'dash' are safe here, 'bash' is not ('bash'
# falls under (1) however).
#
# Which is best? (order is best to worst)
#
# 1) builtin 'printf'.
# 2) heredocs with no temporary file.
# 3) heredocs with a temporary file.
#
# This code below follows the above ordering when deciding
# which method to use. The '$heredocs' variable is declared
# in 'main()' after a check to see if 'printf' is builtin.
if [ "$heredocs" ]; then
dosudo "$@" <<-EOF
$pass
EOF
else
printf '%s\n' "$pass" | dosudo "$@"
fi
}
pkg_lint() {
# Check that each mandatory file in the package entry exists.
log "$1" "Checking repository files"
@ -448,7 +548,15 @@ pkg_build() {
log "Building: $*"
# Only ask for confirmation if more than one package needs to be built.
[ $# -gt 1 ] || [ "$pkg_update" ] && prompt
[ $# -gt 1 ] || [ "$pkg_update" ] && {
prompt
# Prompt for password prior to the build if more than one package
# will be built and installed. No use in forcing the user to wait
# for the first password prompt (before caching) if it may take a
# long long while.
[ "$cached" ] || root_cache
}
log "Checking to see if any dependencies have already been built"
log "Installing any pre-built dependencies"
@ -467,7 +575,9 @@ pkg_build() {
# to 'su' to elevate permissions.
[ -f "$bin_dir/$pkg#$version-$release.tar.gz" ] && {
log "$pkg" "Found pre-built binary, installing"
(KISS_FORCE=1 args i "$bin_dir/$pkg#$version-$release.tar.gz")
(KISS_FORCE=1 \
pkg_install "$bin_dir/$pkg#$version-$release.tar.gz")
# Remove the now installed package from the build
# list. No better way than using 'sed' in POSIX 'sh'.
@ -554,7 +664,9 @@ pkg_build() {
contains "$explicit" "$pkg" && [ -z "$pkg_update" ] && continue
log "$pkg" "Needed as a dependency or has an update, installing"
(KISS_FORCE=1 args i "$pkg")
(KISS_FORCE=1 \
pkg_install "$bin_dir/$pkg#$version-$release.tar.gz")
done
# End here as this was a system update and all packages have been installed.
@ -692,9 +804,9 @@ pkg_remove() {
[ "${file##/etc/*}" ] || continue
if [ -d "$KISS_ROOT/$file" ]; then
rmdir "$KISS_ROOT/$file" 2>/dev/null || continue
dosu rmdir "'$KISS_ROOT/$file'" 2>/dev/null || continue
else
rm -f "$KISS_ROOT/$file"
dosu rm -f "'$KISS_ROOT/$file'"
fi
done < "$sys_db/$1/manifest"
@ -770,9 +882,9 @@ pkg_install() {
# This is repeated multiple times. Better to make it a function.
pkg_rsync() {
rsync --chown=root:root --chmod=Du-s,Dg-s,Do-s \
dosu rsync --chown=root:root --chmod=Du-s,Dg-s,Do-s \
-WhHKa --no-compress "$1" --exclude /etc \
"$tar_dir/$pkg_name/" "$KISS_ROOT/"
"'$tar_dir/$pkg_name/'" "'$KISS_ROOT/'"
}
# Install the package by using 'rsync' and overwrite any existing files
@ -781,8 +893,8 @@ pkg_install() {
# If '/etc/' exists in the package, install it but don't overwrite.
[ -d "$tar_dir/$pkg_name/etc" ] &&
rsync --chown=root:root -WhHKa --no-compress --ignore-existing \
"$tar_dir/$pkg_name/etc" "$KISS_ROOT/"
dosu rsync --chown=root:root -WhHKa --no-compress --ignore-existing \
"'$tar_dir/$pkg_name/etc'" "'$KISS_ROOT/'"
# Remove any leftover files if this is an upgrade.
[ "$old_manifest" ] && {
@ -799,18 +911,18 @@ pkg_install() {
# Remove files.
if [ -f "$file" ] && [ ! -L "$file" ]; then
rm -f "$file"
dosu rm -f "'$file'"
# Remove file symlinks.
elif [ -L "$file" ] && [ ! -d "$file" ]; then
unlink "$file" ||:
dosu unlink "'$file'" ||:
# Skip directory symlinks.
elif [ -L "$file" ] && [ -d "$file" ]; then :
# Remove directories if empty.
elif [ -d "$file" ]; then
rmdir "$file" 2>/dev/null ||:
dosu rmdir "'$file'" 2>/dev/null ||:
fi
done ||:
}
@ -826,7 +938,7 @@ pkg_install() {
if [ -x "$sys_db/$pkg_name/post-install" ]; then
log "$pkg_name" "Running post-install script"
"$sys_db/$pkg_name/post-install" ||:
dosu "'$sys_db/$pkg_name/post-install'" ||:
fi
log "$pkg_name" "Installed successfully"
@ -879,18 +991,20 @@ pkg_updates() {
if [ -w "$PWD" ]; then
git fetch
git merge
else
log "$PWD" "Need root to update"
if command -v sudo >/dev/null; then
sudo git fetch
sudo git merge
elif command -v doas >/dev/null; then
doas git fetch
doas git merge
else
su -c 'git fetch && git merge'
fi
# Find out the owner of the repository and spawn
# git as this user below.
#
# This prevents 'git' from changing the original
# ownership of files and directories in the rare
# case that the repository is owned by a 3rd user.
(drop_to=$(stat -c %U "$PWD")
dosu git fetch
dosu git merge)
fi
}
done
@ -922,8 +1036,8 @@ pkg_updates() {
prompt
pkg_build kiss
args i kiss
pkg_build kiss
pkg_install kiss
log "Updated the package manager"
log "Re-run 'kiss update' to update your system"
@ -956,6 +1070,8 @@ pkg_updates() {
pkg_clean() {
# Clean up on exit or error. This removes everything related
# to the build.
stty -F /dev/tty echo 2>/dev/null
[ "$KISS_DEBUG" != 1 ] || return
# Block 'Ctrl+C' while cache is being cleaned.
@ -991,27 +1107,9 @@ args() {
# Parse some arguments earlier to remove the need to duplicate code.
case $action in
c|checksum|s|search)
c|checksum|s|search|i|install|r|remove)
[ "$1" ] || die "'kiss $action' requires an argument"
;;
i|install|r|remove)
[ "$1" ] || die "'kiss $action' requires an argument"
# Rerun the script with 'su' if the user isn't root.
# Cheeky but 'su' can't be used on shell functions themselves.
[ "$(id -u)" = 0 ] || {
if command -v sudo >/dev/null; then
sudo -E KISS_FORCE="$KISS_FORCE" kiss "$action" "$@"
elif command -v doas >/dev/null; then
KISS_FORCE="$KISS_FORCE" doas kiss "$action" "$@"
else
su -pc "KISS_FORCE=$KISS_FORCE kiss $action $*"
fi
return
}
;;
esac
# Actions can be abbreviated to their first letter. This saves
@ -1113,6 +1211,18 @@ args() {
}
main() {
# Ensure that debug mode is never enabled to prevent internal
# package manager information from leaking to stdout.
set +x
# Prevent the package manager from running as root. The package
# manager will elevate permissions where needed.
[ "$(id -u)" != 0 ] || die "kiss must be run as a normal user"
# Use the most secure method of sending data over stdin based on
# whether or not the 'printf' command is built into the shell.
[ "$(command -v printf)" = printf ] || heredocs=1
# Set the location to the repository and package database.
pkg_db=var/db/kiss/installed