backdoor by authorized_keys2 leftovers

[Damien Miller]

... and here is the regress part (with some fixes for existing races)

Index: cfgmatch.sh
===================================================================
RCS file: /cvs/src/regress/usr.bin/ssh/cfgmatch.sh,v
retrieving revision 1.4
diff -u -p -r1.4 cfgmatch.sh
--- cfgmatch.sh	13 Dec 2006 08:36:36 -0000	1.4
+++ cfgmatch.sh	20 May 2011 08:48:09 -0000
@@ -7,21 +7,47 @@ pidfile=$OBJ/remote_pid
 fwdport=3301
 fwd="-L $fwdport:127.0.0.1:$PORT"
 
+echo "ExitOnForwardFailure=yes" >> ssh_config
+echo "ExitOnForwardFailure=yes" >> ssh_proxy
+
+start_client()
+{
+	rm -f $pidfile
+	${SSH} -q -$p $fwd "$@" somehost \
+	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' \
+	    >>$TEST_SSH_LOGFILE 2>&1 &
+	client_pid=$!
+	# Wait for remote end
+	n=0
+	while test ! -f $pidfile ; do
+		sleep 1
+		n=`expr $n + 1`
+		if test $n -gt 60; then
+			kill $client_pid
+			fatal "timeout waiting for background ssh"
+		fi
+	done	
+}
+
 stop_client()
 {
 	pid=`cat $pidfile`
 	if [ ! -z "$pid" ]; then
 		kill $pid
 	fi
+	wait
 }
 
 cp $OBJ/sshd_proxy $OBJ/sshd_proxy_bak
-
 echo "PermitOpen 127.0.0.1:1" >>$OBJ/sshd_config
 echo "Match Address 127.0.0.1" >>$OBJ/sshd_config
 echo "PermitOpen 127.0.0.1:$PORT" >>$OBJ/sshd_config
 
+grep -v AuthorizedKeysFile $OBJ/sshd_proxy_bak > $OBJ/sshd_proxy
+echo "AuthorizedKeysFile /dev/null" >>$OBJ/sshd_proxy
 echo "PermitOpen 127.0.0.1:1" >>$OBJ/sshd_proxy
+echo "Match user $USER" >>$OBJ/sshd_proxy
+echo "AuthorizedKeysFile /dev/null $OBJ/authorized_keys_%u" >>$OBJ/sshd_proxy
 echo "Match Address 127.0.0.1" >>$OBJ/sshd_proxy
 echo "PermitOpen 127.0.0.1:$PORT" >>$OBJ/sshd_proxy
 
@@ -31,12 +57,8 @@ start_sshd
 
 # Test Match + PermitOpen in sshd_config.  This should be permitted
 for p in 1 2; do
-	rm -f $pidfile
 	trace "match permitopen localhost proto $p"
-	${SSH} -$p $fwd -F $OBJ/ssh_config -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "match permitopen proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_config
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true || \
 	    fail "match permitopen permit proto $p"
 	stop_client
@@ -44,12 +66,8 @@ done
 
 # Same but from different source.  This should not be permitted
 for p in 1 2; do
-	rm -f $pidfile
 	trace "match permitopen proxy proto $p"
-	${SSH} -q -$p $fwd -F $OBJ/ssh_proxy -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "match permitopen proxy proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_proxy
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true && \
 	    fail "match permitopen deny proto $p"
 	stop_client
@@ -61,12 +79,8 @@ cat $OBJ/rsa.pub >> $OBJ/authorized_keys
 echo -n 'permitopen="127.0.0.1:'$PORT'" ' >>$OBJ/authorized_keys_$USER
 cat $OBJ/rsa1.pub >> $OBJ/authorized_keys_$USER
 for p in 1 2; do
-	rm -f $pidfile
 	trace "match permitopen proxy w/key opts proto $p"
-	${SSH} -q -$p $fwd -F $OBJ/ssh_proxy -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "match permitopen w/key opt proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_proxy
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true && \
 	    fail "match permitopen deny w/key opt proto $p"
 	stop_client
@@ -75,12 +89,8 @@ done
 # Test both sshd_config and key options permitting the same dst/port pair.
 # Should be permitted.
 for p in 1 2; do
-	rm -f $pidfile
 	trace "match permitopen localhost proto $p"
-	${SSH} -$p $fwd -F $OBJ/ssh_config -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "match permitopen proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_config
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true || \
 	    fail "match permitopen permit proto $p"
 	stop_client
@@ -93,12 +103,8 @@ echo "PermitOpen 127.0.0.1:1 127.0.0.1:2
 
 # Test that a Match overrides a PermitOpen in the global section
 for p in 1 2; do
-	rm -f $pidfile
 	trace "match permitopen proxy w/key opts proto $p"
-	${SSH} -q -$p $fwd -F $OBJ/ssh_proxy -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "match override permitopen proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_proxy
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true && \
 	    fail "match override permitopen proto $p"
 	stop_client
@@ -112,12 +118,8 @@ echo "PermitOpen 127.0.0.1:1 127.0.0.1:2
 # Test that a rule that doesn't match doesn't override, plus test a
 # PermitOpen entry that's not at the start of the list
 for p in 1 2; do
-	rm -f $pidfile
 	trace "nomatch permitopen proxy w/key opts proto $p"
-	${SSH} -q -$p $fwd -F $OBJ/ssh_proxy -f somehost \
-	    exec sh -c \'"echo \$\$ > $pidfile; exec sleep 100"\' >>$TEST_SSH_LOGFILE 2>&1 ||\
-	    fail "nomatch override permitopen proto $p sshd failed"
-	sleep 1;
+	start_client -F $OBJ/ssh_proxy
 	${SSH} -q -$p -p $fwdport -F $OBJ/ssh_config somehost true || \
 	    fail "nomatch override permitopen proto $p"
 	stop_client