mirror of git://anongit.mindrot.org/openssh.git
496 lines
15 KiB
Bash
496 lines
15 KiB
Bash
# $OpenBSD: agent-restrict.sh,v 1.6 2023/03/01 09:29:32 dtucker Exp $
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# Placed in the Public Domain.
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tid="agent restrictions"
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SSH_AUTH_SOCK="$OBJ/agent.sock"
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export SSH_AUTH_SOCK
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rm -f $SSH_AUTH_SOCK $OBJ/agent.log $OBJ/host_[abcdex]* $OBJ/user_[abcdex]*
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rm -f $OBJ/sshd_proxy_host* $OBJ/ssh_output* $OBJ/expect_*
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rm -f $OBJ/ssh_proxy[._]* $OBJ/command
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verbose "generate keys"
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for h in a b c d e x ca ; do
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$SSHKEYGEN -q -t ed25519 -C host_$h -N '' -f $OBJ/host_$h || \
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fatal "ssh-keygen hostkey failed"
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$SSHKEYGEN -q -t ed25519 -C user_$h -N '' -f $OBJ/user_$h || \
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fatal "ssh-keygen userkey failed"
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done
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# Make some hostcerts
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for h in d e ; do
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id="host_$h"
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$SSHKEYGEN -q -s $OBJ/host_ca -I $id -n $id -h $OBJ/host_${h}.pub || \
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fatal "ssh-keygen certify failed"
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done
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verbose "prepare client config"
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egrep -vi '(identityfile|hostname|hostkeyalias|proxycommand)' \
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$OBJ/ssh_proxy > $OBJ/ssh_proxy.bak
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cat << _EOF > $OBJ/ssh_proxy
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IdentitiesOnly yes
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ForwardAgent yes
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ExitOnForwardFailure yes
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_EOF
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cp $OBJ/ssh_proxy $OBJ/ssh_proxy_noid
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for h in a b c d e ; do
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cat << _EOF >> $OBJ/ssh_proxy
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Host host_$h
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Hostname host_$h
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HostkeyAlias host_$h
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IdentityFile $OBJ/user_$h
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ProxyCommand ${SUDO} env SSH_SK_HELPER=\"$SSH_SK_HELPER\" ${OBJ}/sshd-log-wrapper.sh -i -f $OBJ/sshd_proxy_host_$h
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_EOF
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# Variant with no specified keys.
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cat << _EOF >> $OBJ/ssh_proxy_noid
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Host host_$h
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Hostname host_$h
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HostkeyAlias host_$h
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ProxyCommand ${SUDO} env SSH_SK_HELPER=\"$SSH_SK_HELPER\" ${OBJ}/sshd-log-wrapper.sh -i -f $OBJ/sshd_proxy_host_$h
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_EOF
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done
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cat $OBJ/ssh_proxy.bak >> $OBJ/ssh_proxy
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cat $OBJ/ssh_proxy.bak >> $OBJ/ssh_proxy_noid
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LC_ALL=C
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export LC_ALL
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echo "SetEnv LC_ALL=${LC_ALL}" >> sshd_proxy
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verbose "prepare known_hosts"
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rm -f $OBJ/known_hosts
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for h in a b c x ; do
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(printf "host_$h " ; cat $OBJ/host_${h}.pub) >> $OBJ/known_hosts
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done
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(printf "@cert-authority host_* " ; cat $OBJ/host_ca.pub) >> $OBJ/known_hosts
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verbose "prepare server configs"
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egrep -vi '(hostkey|pidfile)' $OBJ/sshd_proxy \
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> $OBJ/sshd_proxy.bak
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for h in a b c d e; do
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cp $OBJ/sshd_proxy.bak $OBJ/sshd_proxy_host_$h
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cat << _EOF >> $OBJ/sshd_proxy_host_$h
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ExposeAuthInfo yes
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PidFile none
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Hostkey $OBJ/host_$h
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_EOF
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done
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for h in d e ; do
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echo "HostCertificate $OBJ/host_${h}-cert.pub" \
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>> $OBJ/sshd_proxy_host_$h
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done
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# Create authorized_keys with canned command.
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reset_keys() {
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_whichcmd="$1"
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_command=""
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case "$_whichcmd" in
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authinfo) _command="cat \$SSH_USER_AUTH" ;;
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keylist) _command="$SSHADD -L | cut -d' ' -f-2 | sort" ;;
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*) fatal "unsupported command $_whichcmd" ;;
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esac
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trace "reset keys"
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>$OBJ/authorized_keys_$USER
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for h in e d c b a; do
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(printf "%s" "restrict,agent-forwarding,command=\"$_command\" ";
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cat $OBJ/user_$h.pub) >> $OBJ/authorized_keys_$USER
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done
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}
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# Prepare a key for comparison with ExposeAuthInfo/$SSH_USER_AUTH.
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expect_key() {
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_key="$OBJ/${1}.pub"
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_file="$OBJ/$2"
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(printf "publickey " ; cut -d' ' -f-2 $_key) > $_file
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}
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# Prepare expect_* files to compare against authinfo forced command to ensure
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# keys used for authentication match.
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reset_expect_keys() {
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for u in a b c d e; do
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expect_key user_$u expect_$u
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done
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}
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# ssh to host, expecting success and that output matched expectation for
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# that host (expect_$h file).
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expect_succeed() {
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_id="$1"
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_case="$2"
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shift; shift; _extra="$@"
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_host="host_$_id"
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trace "connect $_host expect success"
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rm -f $OBJ/ssh_output
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${SSH} $_extra -F $OBJ/ssh_proxy $_host true > $OBJ/ssh_output
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_s=$?
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test $_s -eq 0 || fail "host $_host $_case fail, exit status $_s"
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diff $OBJ/ssh_output $OBJ/expect_${_id} ||
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fail "unexpected ssh output"
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}
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# ssh to host using explicit key, expecting success and that the key was
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# actually used for authentication.
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expect_succeed_key() {
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_id="$1"
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_key="$2"
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_case="$3"
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shift; shift; shift; _extra="$@"
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_host="host_$_id"
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trace "connect $_host expect success, with key $_key"
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_keyfile="$OBJ/$_key"
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rm -f $OBJ/ssh_output
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${SSH} $_extra -F $OBJ/ssh_proxy_noid \
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-oIdentityFile=$_keyfile $_host true > $OBJ/ssh_output
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_s=$?
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test $_s -eq 0 || fail "host $_host $_key $_case fail, exit status $_s"
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expect_key $_key expect_key
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diff $OBJ/ssh_output $OBJ/expect_key ||
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fail "incorrect key used for authentication"
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}
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# ssh to a host, expecting it to fail.
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expect_fail() {
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_host="$1"
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_case="$2"
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shift; shift; _extra="$@"
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trace "connect $_host expect failure"
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${SSH} $_extra -F $OBJ/ssh_proxy $_host true >/dev/null && \
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fail "host $_host $_case succeeded unexpectedly"
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}
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# ssh to a host using an explicit key, expecting it to fail.
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expect_fail_key() {
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_id="$1"
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_key="$2"
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_case="$3"
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shift; shift; shift; _extra="$@"
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_host="host_$_id"
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trace "connect $_host expect failure, with key $_key"
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_keyfile="$OBJ/$_key"
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${SSH} $_extra -F $OBJ/ssh_proxy_noid -oIdentityFile=$_keyfile \
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$_host true > $OBJ/ssh_output && \
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fail "host $_host $_key $_case succeeded unexpectedly"
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}
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# Move the private key files out of the way to force use of agent-hosted keys.
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hide_privatekeys() {
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trace "hide private keys"
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for u in a b c d e x; do
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mv $OBJ/user_$u $OBJ/user_x$u || fatal "hide privkey $u"
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done
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}
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# Put the private key files back.
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restore_privatekeys() {
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trace "restore private keys"
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for u in a b c d e x; do
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mv $OBJ/user_x$u $OBJ/user_$u || fatal "restore privkey $u"
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done
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}
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clear_agent() {
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${SSHADD} -D > /dev/null 2>&1 || fatal "clear agent failed"
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}
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reset_keys authinfo
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reset_expect_keys
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verbose "authentication w/o agent"
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for h in a b c d e ; do
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expect_succeed $h "w/o agent"
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wrongkey=user_e
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test "$h" = "e" && wrongkey=user_a
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expect_succeed_key $h $wrongkey "\"wrong\" key w/o agent"
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done
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hide_privatekeys
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for h in a b c d e ; do
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expect_fail $h "w/o agent"
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done
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restore_privatekeys
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verbose "start agent"
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${SSHAGENT} ${EXTRA_AGENT_ARGS} -d -a $SSH_AUTH_SOCK > $OBJ/agent.log 2>&1 &
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AGENT_PID=$!
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trap "kill $AGENT_PID" EXIT
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sleep 4 # Give it a chance to start
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# Check that it's running.
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${SSHADD} -l > /dev/null 2>&1
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if [ $? -ne 1 ]; then
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fail "ssh-add -l did not fail with exit code 1"
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fi
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verbose "authentication with agent (no restrict)"
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for u in a b c d e x; do
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$SSHADD -q $OBJ/user_$u || fatal "add key $u unrestricted"
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done
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hide_privatekeys
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for h in a b c d e ; do
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expect_succeed $h "with agent"
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wrongkey=user_e
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test "$h" = "e" && wrongkey=user_a
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expect_succeed_key $h $wrongkey "\"wrong\" key with agent"
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done
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verbose "unrestricted keylist"
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reset_keys keylist
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rm -f $OBJ/expect_list.pre
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# List of keys from agent should contain everything.
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for u in a b c d e x; do
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cut -d " " -f-2 $OBJ/user_${u}.pub >> $OBJ/expect_list.pre
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done
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sort $OBJ/expect_list.pre > $OBJ/expect_list
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for h in a b c d e; do
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cp $OBJ/expect_list $OBJ/expect_$h
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expect_succeed $h "unrestricted keylist"
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done
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restore_privatekeys
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verbose "authentication with agent (basic restrict)"
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reset_keys authinfo
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reset_expect_keys
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for h in a b c d e; do
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$SSHADD -h host_$h -H $OBJ/known_hosts -q $OBJ/user_$h \
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|| fatal "add key $u basic restrict"
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done
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# One more, unrestricted
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$SSHADD -q $OBJ/user_x || fatal "add unrestricted key"
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hide_privatekeys
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# Authentication to host with expected key should work.
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for h in a b c d e ; do
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expect_succeed $h "with agent"
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done
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# Authentication to host with incorrect key should fail.
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verbose "authentication with agent incorrect key (basic restrict)"
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for h in a b c d e ; do
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wrongkey=user_e
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test "$h" = "e" && wrongkey=user_a
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expect_fail_key $h $wrongkey "wrong key with agent (basic restrict)"
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done
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verbose "keylist (basic restrict)"
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reset_keys keylist
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# List from forwarded agent should contain only user_x - the unrestricted key.
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cut -d " " -f-2 $OBJ/user_x.pub > $OBJ/expect_list
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for h in a b c d e; do
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cp $OBJ/expect_list $OBJ/expect_$h
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expect_succeed $h "keylist (basic restrict)"
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done
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restore_privatekeys
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verbose "username"
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reset_keys authinfo
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reset_expect_keys
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for h in a b c d e; do
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$SSHADD -h "${USER}@host_$h" -H $OBJ/known_hosts -q $OBJ/user_$h \
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|| fatal "add key $u basic restrict"
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done
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hide_privatekeys
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for h in a b c d e ; do
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expect_succeed $h "wildcard user"
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done
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restore_privatekeys
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verbose "username wildcard"
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reset_keys authinfo
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reset_expect_keys
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for h in a b c d e; do
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$SSHADD -h "*@host_$h" -H $OBJ/known_hosts -q $OBJ/user_$h \
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|| fatal "add key $u basic restrict"
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done
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hide_privatekeys
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for h in a b c d e ; do
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expect_succeed $h "wildcard user"
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done
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restore_privatekeys
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verbose "username incorrect"
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reset_keys authinfo
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reset_expect_keys
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for h in a b c d e; do
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$SSHADD -h "--BADUSER@host_$h" -H $OBJ/known_hosts -q $OBJ/user_$h \
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|| fatal "add key $u basic restrict"
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done
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hide_privatekeys
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for h in a b c d e ; do
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expect_fail $h "incorrect user"
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done
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restore_privatekeys
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verbose "agent restriction honours certificate principal"
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reset_keys authinfo
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reset_expect_keys
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clear_agent
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$SSHADD -h host_e -H $OBJ/known_hosts -q $OBJ/user_d || fatal "add key"
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hide_privatekeys
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expect_fail d "restricted agent w/ incorrect cert principal"
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restore_privatekeys
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# Prepares the script used to drive chained ssh connections for the
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# multihop tests. Believe me, this is easier than getting the escaping
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# right for 5 hops on the command-line...
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prepare_multihop_script() {
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MULTIHOP_RUN=$OBJ/command
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cat << _EOF > $MULTIHOP_RUN
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#!/bin/sh
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#set -x
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me="\$1" ; shift
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next="\$1"
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if test ! -z "\$me" ; then
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rm -f $OBJ/done
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echo "HOSTNAME host_\$me"
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echo "AUTHINFO"
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cat \$SSH_USER_AUTH
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fi
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echo AGENT
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$SSHADD -L | egrep "^ssh" | cut -d" " -f-2 | sort
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if test -z "\$next" ; then
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touch $OBJ/done
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echo "FINISH"
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e=0
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else
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echo NEXT
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${SSH} -F $OBJ/ssh_proxy_noid -oIdentityFile=$OBJ/user_a \
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host_\$next $MULTIHOP_RUN "\$@"
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e=\$?
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fi
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echo "COMPLETE \"\$me\""
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if test ! -z "\$me" ; then
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if test ! -f $OBJ/done ; then
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echo "DONE MARKER MISSING"
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test \$e -eq 0 && e=63
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fi
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fi
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exit \$e
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_EOF
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chmod u+x $MULTIHOP_RUN
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}
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# Prepare expected output for multihop tests at expect_a
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prepare_multihop_expected() {
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_keys="$1"
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_hops="a b c d e"
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test -z "$2" || _hops="$2"
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_revhops=$(echo "$_hops" | rev)
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_lasthop=$(echo "$_hops" | sed 's/.* //')
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rm -f $OBJ/expect_keys
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for h in a b c d e; do
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cut -d" " -f-2 $OBJ/user_${h}.pub >> $OBJ/expect_keys
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done
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rm -f $OBJ/expect_a
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echo "AGENT" >> $OBJ/expect_a
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test "x$_keys" = "xnone" || sort $OBJ/expect_keys >> $OBJ/expect_a
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echo "NEXT" >> $OBJ/expect_a
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for h in $_hops ; do
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echo "HOSTNAME host_$h" >> $OBJ/expect_a
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echo "AUTHINFO" >> $OBJ/expect_a
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(printf "publickey " ; cut -d" " -f-2 $OBJ/user_a.pub) >> $OBJ/expect_a
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echo "AGENT" >> $OBJ/expect_a
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if test "x$_keys" = "xall" ; then
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sort $OBJ/expect_keys >> $OBJ/expect_a
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fi
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if test "x$h" != "x$_lasthop" ; then
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if test "x$_keys" = "xfiltered" ; then
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cut -d" " -f-2 $OBJ/user_a.pub >> $OBJ/expect_a
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fi
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echo "NEXT" >> $OBJ/expect_a
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fi
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done
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echo "FINISH" >> $OBJ/expect_a
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for h in $_revhops "" ; do
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echo "COMPLETE \"$h\"" >> $OBJ/expect_a
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done
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}
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prepare_multihop_script
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cp $OBJ/user_a.pub $OBJ/authorized_keys_$USER # only one key used.
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verbose "multihop without agent"
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clear_agent
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prepare_multihop_expected none
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output || fail "multihop no agent ssh failed"
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diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
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verbose "multihop agent unrestricted"
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clear_agent
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$SSHADD -q $OBJ/user_[abcde]
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prepare_multihop_expected all
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output || fail "multihop no agent ssh failed"
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diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
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verbose "multihop restricted"
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clear_agent
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prepare_multihop_expected filtered
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# Add user_a, with permission to connect through the whole chain.
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$SSHADD -h host_a -h "host_a>host_b" -h "host_b>host_c" \
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-h "host_c>host_d" -h "host_d>host_e" \
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-H $OBJ/known_hosts -q $OBJ/user_a \
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|| fatal "add key user_a multihop"
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# Add the other keys, bound to a unused host.
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$SSHADD -q -h host_x -H $OBJ/known_hosts $OBJ/user_[bcde] || fail "add keys"
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hide_privatekeys
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output || fail "multihop ssh failed"
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diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
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restore_privatekeys
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verbose "multihop username"
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$SSHADD -h host_a -h "host_a>${USER}@host_b" -h "host_b>${USER}@host_c" \
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-h "host_c>${USER}@host_d" -h "host_d>${USER}@host_e" \
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-H $OBJ/known_hosts -q $OBJ/user_a || fatal "add key user_a multihop"
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hide_privatekeys
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output || fail "multihop w/ user ssh failed"
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diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
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restore_privatekeys
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verbose "multihop wildcard username"
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$SSHADD -h host_a -h "host_a>*@host_b" -h "host_b>*@host_c" \
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-h "host_c>*@host_d" -h "host_d>*@host_e" \
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-H $OBJ/known_hosts -q $OBJ/user_a || fatal "add key user_a multihop"
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hide_privatekeys
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output || fail "multihop w/ user ssh failed"
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diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
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restore_privatekeys
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verbose "multihop wrong username"
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$SSHADD -h host_a -h "host_a>*@host_b" -h "host_b>*@host_c" \
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-h "host_c>--BADUSER@host_d" -h "host_d>*@host_e" \
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-H $OBJ/known_hosts -q $OBJ/user_a || fatal "add key user_a multihop"
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hide_privatekeys
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$MULTIHOP_RUN "" a b c d e > $OBJ/ssh_output && \
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fail "multihop with wrong user succeeded unexpectedly"
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restore_privatekeys
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verbose "multihop cycle no agent"
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clear_agent
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prepare_multihop_expected none "a b a a c d e"
|
|
$MULTIHOP_RUN "" a b a a c d e > $OBJ/ssh_output || \
|
|
fail "multihop cycle no-agent fail"
|
|
diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
|
|
|
|
verbose "multihop cycle agent unrestricted"
|
|
clear_agent
|
|
$SSHADD -q $OBJ/user_[abcde] || fail "add keys"
|
|
prepare_multihop_expected all "a b a a c d e"
|
|
$MULTIHOP_RUN "" a b a a c d e > $OBJ/ssh_output || \
|
|
fail "multihop cycle agent ssh failed"
|
|
diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
|
|
|
|
verbose "multihop cycle restricted deny"
|
|
clear_agent
|
|
$SSHADD -q -h host_x -H $OBJ/known_hosts $OBJ/user_[bcde] || fail "add keys"
|
|
$SSHADD -h host_a -h "host_a>host_b" -h "host_b>host_c" \
|
|
-h "host_c>host_d" -h "host_d>host_e" \
|
|
-H $OBJ/known_hosts -q $OBJ/user_a \
|
|
|| fatal "add key user_a multihop"
|
|
prepare_multihop_expected filtered "a b a a c d e"
|
|
hide_privatekeys
|
|
$MULTIHOP_RUN "" a b a a c d e > $OBJ/ssh_output && \
|
|
fail "multihop cycle restricted deny succeded unexpectedly"
|
|
restore_privatekeys
|
|
|
|
verbose "multihop cycle restricted allow"
|
|
clear_agent
|
|
$SSHADD -q -h host_x -H $OBJ/known_hosts $OBJ/user_[bcde] || fail "add keys"
|
|
$SSHADD -h host_a -h "host_a>host_b" -h "host_b>host_c" \
|
|
-h "host_c>host_d" -h "host_d>host_e" \
|
|
-h "host_b>host_a" -h "host_a>host_a" -h "host_a>host_c" \
|
|
-H $OBJ/known_hosts -q $OBJ/user_a \
|
|
|| fatal "add key user_a multihop"
|
|
prepare_multihop_expected filtered "a b a a c d e"
|
|
hide_privatekeys
|
|
$MULTIHOP_RUN "" a b a a c d e > $OBJ/ssh_output || \
|
|
fail "multihop cycle restricted allow failed"
|
|
diff $OBJ/ssh_output $OBJ/expect_a || fail "unexpected ssh output"
|
|
restore_privatekeys
|
|
|