1#	$OpenBSD: keys-command.sh,v 1.7 2021/09/01 00:50:27 dtucker Exp $
2#	Placed in the Public Domain.
3
4tid="authorized keys from command"
5
6if [ -z "$SUDO" -a ! -w /var/run ]; then
7	echo "skipped (SUDO not set)"
8	echo "need SUDO to create file in /var/run, test won't work without"
9	exit 0
10fi
11
12rm -f $OBJ/keys-command-args
13
14touch $OBJ/keys-command-args
15chmod a+rw $OBJ/keys-command-args
16
17expected_key_text=`awk '{ print $2 }' < $OBJ/ssh-ed25519.pub`
18expected_key_fp=`$SSHKEYGEN -lf $OBJ/ssh-ed25519.pub | awk '{ print $2 }'`
19
20# Establish a AuthorizedKeysCommand in /var/run where it will have
21# acceptable directory permissions.
22KEY_COMMAND="/var/run/keycommand_${LOGNAME}.$$"
23trap "${SUDO} rm -f ${KEY_COMMAND}" 0
24cat << _EOF | $SUDO sh -c "rm -f '$KEY_COMMAND' ; cat > '$KEY_COMMAND'"
25#!/bin/sh
26echo args: "\$@" >> $OBJ/keys-command-args
27echo "$PATH" | grep -q mekmitasdigoat && exit 7
28test "x\$1" != "x${LOGNAME}" && exit 1
29if test $# -eq 6 ; then
30	test "x\$2" != "xblah" && exit 2
31	test "x\$3" != "x${expected_key_text}" && exit 3
32	test "x\$4" != "xssh-rsa" && exit 4
33	test "x\$5" != "x${expected_key_fp}" && exit 5
34	test "x\$6" != "xblah" && exit 6
35fi
36exec cat "$OBJ/authorized_keys_${LOGNAME}"
37_EOF
38$SUDO chmod 0755 "$KEY_COMMAND"
39
40if ! $OBJ/check-perm -m keys-command $KEY_COMMAND ; then
41	echo "skipping: $KEY_COMMAND is unsuitable as AuthorizedKeysCommand"
42	$SUDO rm -f $KEY_COMMAND
43	exit 0
44fi
45
46if [ -x $KEY_COMMAND ]; then
47	cp $OBJ/sshd_proxy $OBJ/sshd_proxy.bak
48
49	verbose "AuthorizedKeysCommand with arguments"
50	(
51		grep -vi AuthorizedKeysFile $OBJ/sshd_proxy.bak
52		echo AuthorizedKeysFile none
53		echo AuthorizedKeysCommand $KEY_COMMAND %u blah %k %t %f blah
54		echo AuthorizedKeysCommandUser ${LOGNAME}
55	) > $OBJ/sshd_proxy
56
57	# Ensure that $PATH is sanitised in sshd
58	env PATH=$PATH:/sbin/mekmitasdigoat \
59	    ${SSH} -F $OBJ/ssh_proxy somehost true
60	if [ $? -ne 0 ]; then
61		fail "connect failed"
62	fi
63
64	verbose "AuthorizedKeysCommand without arguments"
65	# Check legacy behavior of no-args resulting in username being passed.
66	(
67		grep -vi AuthorizedKeysFile $OBJ/sshd_proxy.bak
68		echo AuthorizedKeysFile none
69		echo AuthorizedKeysCommand $KEY_COMMAND
70		echo AuthorizedKeysCommandUser ${LOGNAME}
71	) > $OBJ/sshd_proxy
72
73	# Ensure that $PATH is sanitised in sshd
74	env PATH=$PATH:/sbin/mekmitasdigoat \
75	    ${SSH} -F $OBJ/ssh_proxy somehost true
76	if [ $? -ne 0 ]; then
77		fail "connect failed"
78	fi
79else
80	skip "$KEY_COMMAND not executable (/var/run mounted noexec?)"
81fi
82