dropbear: failsafe: handle all supported key types

dropbear may be configured and compiled with support for different host key types

Signed-off-by: Konstantin Demin <rockdrilla@gmail.com>

diff --git a/package/network/services/dropbear/files/dropbear.failsafe b/package/network/services/dropbear/files/dropbear.failsafe
index 97bd12d58a18910807892c0fa4ce5b10b43c627d..417265babed6dff1cd3661486cf84485df7ef1ed 100755 (executable)
--- a/package/network/services/dropbear/files/dropbear.failsafe
+++ b/package/network/services/dropbear/files/dropbear.failsafe
@@ -1,9 +1,61 @@
 #!/bin/sh
 
+_dropbear()
+{
+       /usr/sbin/dropbear "$@" </dev/null >/dev/null 2>&1
+}
+
+_dropbearkey()
+{
+       /usr/bin/dropbearkey "$@" </dev/null >/dev/null 2>&1
+}
+
+_ensurekey()
+{
+       _dropbearkey -y -f "$1" && return
+       rm -f "$1"
+       _dropbearkey -f "$@" || {
+               rm -f "$1"
+               return 1
+       }
+}
+
+ktype_all='ed25519 ecdsa rsa'
+
 failsafe_dropbear () {
-       dropbearkey -t rsa -s 1024 -f /tmp/dropbear_rsa_failsafe_host_key
-       dropbearkey -t ed25519 -f /tmp/dropbear_ed25519_failsafe_host_key
-       dropbear -r /tmp/dropbear_rsa_failsafe_host_key -r /tmp/dropbear_ed25519_failsafe_host_key <> /dev/null 2>&1
+       local kargs kcount ktype tkey
+
+       kargs=
+       kcount=0
+       for ktype in ${ktype_all} ; do
+               tkey="/tmp/dropbear_failsafe_${ktype}_host_key"
+
+               case "${ktype}" in
+               ed25519) _ensurekey "${tkey}" -t ed25519 ;;
+               ecdsa)   _ensurekey "${tkey}" -t ecdsa -s 256 ;;
+               rsa)     _ensurekey "${tkey}" -t rsa   -s 1024 ;;
+               *)
+                       echo "unknown key type: ${ktype}" >&2
+                       continue
+               ;;
+               esac
+
+               [ -s "${tkey}" ] || {
+                       rm -f "${tkey}"
+                       continue
+               }
+
+               chmod 0400 "${tkey}"
+               kargs="${kargs}${kargs:+ }-r ${tkey}"
+               kcount=$((kcount+1))
+       done
+
+       [ "${kcount}" != 0 ] || {
+               echo 'DROPBEAR IS BROKEN' >&2
+               return 1
+       }
+
+       _dropbear ${kargs}
 }
 
 boot_hook_add failsafe failsafe_dropbear