1# $OpenBSD: keys-command.sh,v 1.6 2019/07/25 08:48:11 dtucker Exp $ 2# Placed in the Public Domain. 3 4tid="authorized keys from command" 5 6if [ -z "$SUDO" -a ! -w /var/run ]; then 7 fatal "need SUDO to create file in /var/run, test won't work without" 8fi 9 10rm -f $OBJ/keys-command-args 11 12touch $OBJ/keys-command-args 13chmod a+rw $OBJ/keys-command-args 14 15expected_key_text=`awk '{ print $2 }' < $OBJ/ssh-ed25519.pub` 16expected_key_fp=`$SSHKEYGEN -lf $OBJ/ssh-ed25519.pub | awk '{ print $2 }'` 17 18# Establish a AuthorizedKeysCommand in /var/run where it will have 19# acceptable directory permissions. 20KEY_COMMAND="/var/run/keycommand_${LOGNAME}.$$" 21trap "${SUDO} rm -f ${KEY_COMMAND}" 0 22cat << _EOF | $SUDO sh -c "rm -f '$KEY_COMMAND' ; cat > '$KEY_COMMAND'" 23#!/bin/sh 24echo args: "\$@" >> $OBJ/keys-command-args 25echo "$PATH" | grep -q mekmitasdigoat && exit 7 26test "x\$1" != "x${LOGNAME}" && exit 1 27if test $# -eq 6 ; then 28 test "x\$2" != "xblah" && exit 2 29 test "x\$3" != "x${expected_key_text}" && exit 3 30 test "x\$4" != "xssh-rsa" && exit 4 31 test "x\$5" != "x${expected_key_fp}" && exit 5 32 test "x\$6" != "xblah" && exit 6 33fi 34exec cat "$OBJ/authorized_keys_${LOGNAME}" 35_EOF 36$SUDO chmod 0755 "$KEY_COMMAND" 37 38if [ -x $KEY_COMMAND ]; then 39 cp $OBJ/sshd_proxy $OBJ/sshd_proxy.bak 40 41 verbose "AuthorizedKeysCommand with arguments" 42 ( 43 grep -vi AuthorizedKeysFile $OBJ/sshd_proxy.bak 44 echo AuthorizedKeysFile none 45 echo AuthorizedKeysCommand $KEY_COMMAND %u blah %k %t %f blah 46 echo AuthorizedKeysCommandUser ${LOGNAME} 47 ) > $OBJ/sshd_proxy 48 49 # Ensure that $PATH is sanitised in sshd 50 env PATH=$PATH:/sbin/mekmitasdigoat \ 51 ${SSH} -F $OBJ/ssh_proxy somehost true 52 if [ $? -ne 0 ]; then 53 fail "connect failed" 54 fi 55 56 verbose "AuthorizedKeysCommand without arguments" 57 # Check legacy behavior of no-args resulting in username being passed. 58 ( 59 grep -vi AuthorizedKeysFile $OBJ/sshd_proxy.bak 60 echo AuthorizedKeysFile none 61 echo AuthorizedKeysCommand $KEY_COMMAND 62 echo AuthorizedKeysCommandUser ${LOGNAME} 63 ) > $OBJ/sshd_proxy 64 65 # Ensure that $PATH is sanitised in sshd 66 env PATH=$PATH:/sbin/mekmitasdigoat \ 67 ${SSH} -F $OBJ/ssh_proxy somehost true 68 if [ $? -ne 0 ]; then 69 fail "connect failed" 70 fi 71else 72 echo "SKIPPED: $KEY_COMMAND not executable (/var/run mounted noexec?)" 73fi 74