__sshd config: New type

cdist/conf/type/__sshd_config/explorer/state

@@ -0,0 +1,121 @@
+#!/bin/sh -e
+#
+# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+# Determines the current state of the config option.
+# Possible output:
+#  - present: "should" option present in config file
+#  - default: the "should" option is the default -> don’t know if present
+#  - absent: no such option present in config file
+#
+
+joinlines() { sed -n -e H -e "\${x;s/^\\n//;s/\\n/${1:?}/g;p;}"; }
+trlower() { tr '[:upper:]' '[:lower:]'; }
+tolower() { printf '%s' "$*" | trlower; }
+
+default_value() {
+	sshd -T -f /dev/null -C "$(make_conn_spec)" \
+	| sed -n -e 's/^'"$(tolower "${1:?}")"'[[:blank:]]\{1,\}//p'
+}
+
+make_conn_spec() {
+	if test -s "${__object:?}/parameter/match"
+	then
+		_match_file="${__object:?}/parameter/match"
+	else
+		_match_file='/dev/null'
+	fi
+
+	for _kw in \
+		addr=Address \
+		user=User \
+		host=Host \
+		laddr=LocalAddress \
+		lport=LocalPort \
+		rdomain=RDomain
+	do
+		_specname=${_kw%%=*}
+		_confname=$(tolower "${_kw#*=}")
+		while read -r _k _v
+		do
+			if test "$(tolower "${_k}")" = "${_confname}"
+			then
+				printf '%s=%s\n' "${_specname}" "${_v}"
+				continue 2
+			fi
+		done <"${_match_file}"
+
+		# NOTE: Print test spec even for empty keys to suppress errors like:
+		#  'Match User' in configuration but 'user' not in connection test specification.
+		# except lport:
+		#  Invalid port '' in test mode specification lport=
+		test "${_specname}" = 'lport' || printf '%s=\n' "${_specname}"
+	done \
+	| joinlines ','
+	unset _match_file
+}
+
+sshd_config_file=$(cat "${__object:?}/parameter/file")
+state_should=$(cat "${__object:?}/parameter/state")
+
+if test -s "${__object:?}/parameter/option"
+then
+	option_name=$(cat "${__object:?}/parameter/option")
+else
+	option_name=${__object_id:?}
+fi
+
+value_should=$(cat "${__object:?}/parameter/value" 2>/dev/null) \
+|| test "${state_should}" = absent || exit 0  # param optional if --state absent
+
+command -v sshd >/dev/null 2>&1 || {
+	echo 'Cannot find sshd.' >&2
+	exit 1
+}
+
+test -e "${sshd_config_file}" || {
+	echo 'absent'
+	exit 0
+}
+
+value_is=$(
+	sshd -T -f "${sshd_config_file}" -C "$(make_conn_spec)" \
+	| sed -n -e 's/^'"$(tolower "${option_name}")"'[[:blank:]]\{1,\}//p')
+
+if printf '%s\n' "${value_is}" | {
+		if test -n "${value_should}"
+		then
+			grep -q -x -F "${value_should}"
+		else
+			# if no value provided, assume "any" value
+			grep -q -e .
+		fi
+	}
+then
+	if default_value "${option_name}" | grep -q -x -F "${value_is}"
+	then
+		# Might produce false positives for default values.
+		# TODO: Manual checking should be done, but for simplicity, this case is
+		#       currently ignored here.
+		echo default
+	else
+		echo present
+	fi
+else
+	echo absent
+fi

cdist/conf/type/__sshd_config/files/update_sshd_config.awk

@@ -0,0 +1,293 @@
+# -*- mode: awk; indent-tabs-mode: t -*-
+
+function usage() {
+	print_err("Usage: awk -f update_sshd_config.awk -- -o set|unset [-m 'User git'] -l 'X11Forwarding no' /etc/ssh/sshd_config")
+}
+
+function print_err(s) { print s | "cat >&2" }
+
+function alength(a,    i) {
+	for (i = 0; (i + 1) in a; ++i);
+	return i
+}
+
+function join(sep, a, i,    s) {
+	for (i = i ? i : 1; i in a; i++)
+		s = s sep a[i]
+	return substr(s, 2)
+}
+
+function getopt(opts, argv, target, files,    i, c, lv, idx, nf) {
+	# trivial getopt(3) implementation; only basic functionality
+	if (argv[1] == "--") i++
+	for (i += 1; i in argv; i++) {
+		if (lv) { target[c] = argv[i]; lv = 0; continue }
+		if (argv[i] ~ /^-/) {
+			c = substr(argv[i], 2, 1)
+			idx = index(opts, c)
+			if (!idx) {
+				print_err(sprintf("invalid option -%c\n", c))
+				continue
+			}
+			if (substr(opts, idx + 1, 1) == ":") {
+				# option takes argument
+				if (length(argv[i]) > 2)
+					target[c] = substr(argv[i], 3)
+				else
+					lv = 1
+			} else {
+				target[c] = 1
+			}
+		} else
+			files[++nf] = argv[i]
+	}
+}
+
+# tokenise configuration line
+# this function mimics the counterpart in OpenSSH (misc.c)
+# but it returns two (next token SUBSEP rest) because I didn’t want to have to
+# simulate any pointer magic.
+function strdelim_internal(s, split_equals,    old) {
+	if (!s)
+		return ""
+
+	old = s
+
+	if (!match(s, WHITESPACE "|" QUOTE "" (split_equals ? "|" EQUALS : "")))
+		return s
+
+	s = substr(s, RSTART)
+	old = substr(old, 1, RSTART - 1)
+
+	if (s ~ "^" QUOTE) {
+		old = substr(old, 2)
+
+		# Find matching quote
+		if (match(s, QUOTE)) {
+			old = substr(old, 1, RSTART)
+			# s = substr()
+			if (match(s, "^" WHITESPACE "*"))
+				s = substr(s, RLENGTH)
+			return old
+		} else {
+			# no matching quote
+			return ""
+		}
+	}
+
+	if (match(s, "^" WHITESPACE "+")) {
+		sub("^" WHITESPACE "+", "", s)
+		if (split_equals)
+			sub(EQUALS WHITESPACE "*", "", s)
+	} else if (s ~ "^" EQUALS) {
+		s = substr(s, 2)
+	}
+
+	return old SUBSEP s
+}
+function strdelim(s) { return strdelim_internal(s, 1) }
+function strdelimw(s) { return strdelim_internal(s, 0) }
+
+function singleton_option(opt) {
+	return tolower(opt) !~ /^(acceptenv|allowgroups|allowusers|authenticationmethods|authorizedkeysfile|denygroups|denyusers|hostcertificate|hostkey|listenaddress|logverbose|permitlisten|permitopen|port|setenv|subsystem)$/
+}
+
+function print_update() {
+	if (mode) {
+		if (match_only) printf "\t"
+		printf "%s\n", line_should
+		updated = 1
+	}
+}
+
+BEGIN {
+	FS = "\n"  # disable field splitting
+
+	WHITESPACE = "[ \t]"  # servconf.c, misc.c:strdelim_internal (without line breaks, cf. bugs)
+	QUOTE = "[\"]"  # misc.c:strdelim_internal
+	EQUALS = "[=]"
+
+	split("", opts)
+	split("", files)
+	getopt("ho:l:m:", ARGV, opts, files)
+
+	if (opts["h"]) { usage(); exit (e="0") }
+
+	line_should = opts["l"]
+	match_only = opts["m"]
+	num_files = alength(files)
+
+	if (num_files != 1 || !opts["o"] || !line_should) {
+		usage()
+		exit (e=126)
+	}
+
+	if (opts["o"] == "set") {
+		mode = 1
+	} else if (opts["o"] == "unset") {
+		mode = 0
+	} else {
+		print_err(sprintf("invalid mode %s\n", mode))
+		exit (e=1)
+	}
+
+	if (mode) {
+		# loop over sshd_config twice!
+		ARGV[2] = ARGV[1] = files[1]
+		ARGC = 3
+	} else {
+		# only loop once
+		ARGV[1] = files[1]
+		ARGC = 2
+	}
+
+	split(strdelim(line_should), should, SUBSEP)
+	option_should = tolower(should[1])
+	value_should = should[2]
+}
+
+{
+	line = $0
+
+	# Strip trailing whitespace. Allow \f (form feed) at EOL only
+	sub("(" WHITESPACE "|\f)*$", "", line)
+
+	# Strip leading whitespace
+	sub("^" WHITESPACE "*", "", line)
+
+	if (match(line, "^#" WHITESPACE "*")) {
+		prefix = substr(line, RSTART, RLENGTH)
+		line = substr(line, RSTART + RLENGTH)
+	} else {
+		prefix = ""
+	}
+
+	line_type = "invalid"
+	option_is = value_is = ""
+
+	if (line) {
+		split(strdelim(line), toks, SUBSEP)
+
+		if (tolower(toks[1]) == "match") {
+			MATCH = (prefix ~ /^#/ ? "#" : "") join(" ", toks, 2)
+			line_type = "match"
+		} else if (toks[1] ~ /^[A-Za-z][A-Za-z0-9]+$/) {
+			# This could be an option line
+			line_type = "option"
+			option_is = tolower(toks[1])
+			value_is = toks[2]
+		}
+	} else {
+		line_type = "empty"
+	}
+}
+
+# mode: unset
+
+!mode {
+	# delete matching config
+	if (prefix !~ /^#/)
+		if (MATCH == match_only && option_is == option_should)
+			if (!value_should || value_should == value_is)
+				next
+
+	print
+	next
+}
+
+
+# mode: set
+
+mode && NR == FNR {
+	if (line_type == "option") {
+		if (MATCH !~ /^#/) {
+			if (prefix ~ /^#/) {
+				# comment line
+				last_occ[MATCH, "#" option_is] = FNR
+			} else {
+				# option line
+				last_occ[MATCH, option_is] = FNR
+			}
+			last_occ[MATCH] = FNR
+		}
+	} else if (line_type == "invalid" && !prefix) {
+		# INVALID LINE
+		print_err(sprintf("%s: syntax error on line %u\n", ARGV[0], FNR))
+	}
+
+	next
+}
+
+# before second pass prepare hashes containing location information to be used
+# in the second pass.
+mode && NR > FNR && FNR == 1 {
+	# First we drop the locations of commented-out options if a non-commented
+	# option is available. If a non-commented option is available, we will
+	# append new config options there to have them all at one place.
+	for (k in last_occ) {
+		if (k ~ /^#/) {
+			# delete entries of commented out match blocks
+			delete last_occ[k]
+			continue
+		}
+
+		split(k, parts, SUBSEP)
+
+		if (parts[2] ~ /^#/ && ((parts[1], substr(parts[2], 2)) in last_occ))
+			delete last_occ[k]
+	}
+
+	# Reverse the option => line mapping. The line_map allows for easier lookups
+	# in the second pass.
+	# We only keep options, not top-level keywords, because we can only have
+	# one entry per line and there are conflicts with last lines of "sections".
+	for (k in last_occ) {
+		if (!index(k, SUBSEP)) continue
+		line_map[last_occ[k]] = k
+	}
+}
+
+# Second pass
+mode && line_map[FNR] == match_only SUBSEP option_should && !updated {
+	split(line_map[FNR], parts, SUBSEP)
+
+	# If option allows multiple values, print current value
+	if (!singleton_option(parts[2])) {
+		if (value_should != value_is)
+			print
+	}
+
+	print_update()
+
+	next
+}
+
+mode { print }
+
+# Is a comment option
+mode && line_map[FNR] == match_only SUBSEP "#" option_should && !updated {
+	print_update()
+}
+
+# Last line of the should match section
+mode && last_occ[match_only] == FNR && !updated {
+	# NOTE: Inserting empty lines is only cosmetic.  It is only done if
+	#       different options are next to each other and not in a match block
+	#       (match blocks are usually not in the default config and thus don’t
+	#       contain commented blocks.)
+	if (line && option_is != option_should && !MATCH)
+		print ""
+	print_update()
+}
+
+END {
+	if (e) exit e
+
+	if (mode && !updated) {
+		if (match_only && MATCH != match_only) {
+			printf "\nMatch %s\n", match_only
+		}
+
+		print_update()
+	}
+}

cdist/conf/type/__sshd_config/gencode-remote

@@ -0,0 +1,97 @@
+#!/bin/sh -e
+#
+# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+
+joinlines() { sed -n -e H -e "\${x;s/^\\n//;s/\\n/${1:?}/g;p;}"; }
+
+state_is=$(cat "${__object:?}/explorer/state")
+state_should=$(cat "${__object:?}/parameter/state")
+
+if test "${state_is}" = "${state_should}" -o "${state_is}" = 'default'
+then
+	# nothing to do (if the value is the default, ignore its state)
+	exit 0
+fi
+
+case ${state_should}
+in
+	(present)
+		mode='set'
+		;;
+	(absent)
+		mode='unset'
+		;;
+	(*)
+		printf 'Invalid --state: %s\n' "${state_should}" >&2
+		exit 1
+		;;
+esac
+
+sshd_config_file=$(cat "${__object:?}/parameter/file")
+
+quote() { printf "'%s'" "$(printf '%s' "$*" | sed -e "s/'/'\\\\''/g")"; }
+drop_awk_comments() { quote "$(sed '/^[[:blank:]]*#.*$/d;/^$/d' "$@")"; }
+
+# Ensure the sshd_config file is there
+cat <<EOF
+test -e $(quote "${sshd_config_file}") || {
+	 : >$(quote "${sshd_config_file}")
+	 chown 0:0 $(quote "${sshd_config_file}")
+	 chmod 0644 $(quote "${sshd_config_file}")
+}
+
+EOF
+
+match_only=
+if test -s "${__object:?}/parameter/match"
+then
+	match_only=$(joinlines ' ' <"${__object:?}/parameter/match")
+fi
+
+if test -s "${__object:?}/parameter/option"
+then
+	option_line=$(cat "${__object:?}/parameter/option")
+else
+	option_line=${__object_id:?}
+fi
+
+if test -s "${__object:?}/parameter/value"
+then
+	option_line="${option_line} $(cat "${__object:?}/parameter/value")"
+fi
+
+# Send message on config update
+printf '%s%s %s\n' "${mode}" "${match_only:+ [${match_only}]}" \
+	"${option_line}" >>"${__messages_out:?}"
+
+# Update sshd_config (remote code)
+cat <<EOF
+awk $(drop_awk_comments "${__type:?}/files/update_sshd_config.awk") \\
+	-o ${mode} \\
+	-m $(quote "${match_only}") \\
+	-l $(quote "${option_line}") \\
+	$(quote "${sshd_config_file}") >$(quote "${sshd_config_file}.tmp") \\
+|| exit
+
+cmp -s $(quote "${sshd_config_file}") $(quote "${sshd_config_file}.tmp") || {
+	sshd -t -f $(quote "${sshd_config_file}.tmp") \\
+	&& cat $(quote "${sshd_config_file}.tmp") >$(quote "${sshd_config_file}")
+}
+rm -f $(quote "${sshd_config_file}.tmp")
+EOF

cdist/conf/type/__sshd_config/man.rst

@@ -0,0 +1,94 @@
+cdist-type__sshd_config(7)
+==========================
+
+NAME
+----
+cdist-type__sshd_config - Manage options in sshd_config
+
+
+DESCRIPTION
+-----------
+This space intentionally left blank.
+
+
+REQUIRED PARAMETERS
+-------------------
+None.
+
+
+OPTIONAL PARAMETERS
+-------------------
+file
+    The path to the sshd_config file to edit.
+    Defaults to ``/etc/ssh/sshd_config``.
+match
+    Restrict this option to apply only for certain connections.
+    Allowed values are what would be allowed to be written after a ``Match``
+    keyword in ``sshd_config``, e.g. ``--match 'User anoncvs'``.
+
+    Can be used multiple times. All of the values are ANDed together.
+option
+    The name of the option to manipulate. Defaults to ``__object_id``.
+state
+    Can be:
+
+    - ``present``: ensure a matching config line is present (or the default
+      value).
+    - ``absent``: ensure no matching config line is present.
+value
+    The option's value to be assigned to the option (if ``--state present``) or
+    removed (if ``--state absent``).
+
+    This option is required if ``--state present``. If not specified and
+    ``--state absent``, all values for the given option are removed.
+
+
+BOOLEAN PARAMETERS
+------------------
+None.
+
+
+EXAMPLES
+--------
+
+.. code-block:: sh
+
+    # Disallow root logins with password
+    __sshd_config PermitRootLogin --value without-password
+
+    # Disallow password-based authentication
+    __sshd_config PasswordAuthentication --value no
+
+    # Accept the EDITOR environment variable
+    __sshd_config AcceptEnv:EDITOR --option AcceptEnv --value EDITOR
+
+    # Force command for connections as git user
+    __sshd_config git@ForceCommand --match 'User git' --option ForceCommand \
+        --value 'cd ~git && exec git-shell ${SSH_ORIGINAL_COMMAND:+-c "${SSH_ORIGINAL_COMMAND}"}'
+
+
+SEE ALSO
+--------
+:strong:`sshd_config`\ (5)
+
+
+BUGS
+----
+- This type assumes a nicely formatted config file,
+  i.e. no config options spanning multiple lines.
+- ``Include`` directives are ignored.
+- Config options are not added/removed to/from the config file if their value is
+  the default value.
+
+
+AUTHORS
+-------
+Dennis Camera <dennis.camera--@--ssrq-sds-fds.ch>
+
+
+COPYING
+-------
+Copyright \(C) 2020 Dennis Camera. You can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.

cdist/conf/type/__sshd_config/manifest

@@ -0,0 +1,48 @@
+#!/bin/sh -e
+#
+# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+
+os=$(cat "${__global:?}/explorer/os")
+
+state_should=$(cat "${__object:?}/parameter/state")
+
+case ${os}
+in
+	(alpine|centos|fedora|redhat|scientific|debian|devuan|ubuntu)
+		if test "${state_should}" != 'absent'
+		then
+			__package openssh-server --state present
+		fi
+		;;
+	(archlinux|gentoo|slackware|suse)
+		if test "${state_should}" != 'absent'
+		then
+			__package openssh --state present
+		fi
+		;;
+	(freebsd|netbsd|openbsd)
+		# whitelist
+		;;
+	(*)
+		printf 'Your operating system (%s) is currently not supported by this type (%s)\n' \
+			"${os}" "${__type##*/}" >&2
+		printf 'Please contribute an implementation for it if you can.\n' >&2
+		exit 1
+		;;
+esac

cdist/conf/type/__sshd_config/parameter/default/file

@@ -0,0 +1 @@
+/etc/ssh/sshd_config

cdist/conf/type/__sshd_config/parameter/default/state

@@ -0,0 +1 @@
+present

cdist/conf/type/__sshd_config/parameter/optional

@@ -0,0 +1,4 @@
+file
+option
+state
+value

cdist/conf/type/__sshd_config/parameter/optional_multiple

@@ -0,0 +1 @@
+match