diff options
Diffstat (limited to 'src/monkeysphere-ssh-proxycommand')
| -rwxr-xr-x | src/monkeysphere-ssh-proxycommand | 154 |
1 files changed, 152 insertions, 2 deletions
diff --git a/src/monkeysphere-ssh-proxycommand b/src/monkeysphere-ssh-proxycommand index 6276092..b3dc562 100755 --- a/src/monkeysphere-ssh-proxycommand +++ b/src/monkeysphere-ssh-proxycommand @@ -14,13 +14,130 @@ # ProxyCommand monkeysphere-ssh-proxycommand %h %p ######################################################################## +PGRM=$(basename $0) + +SYSSHAREDIR=${MONKEYSPHERE_SYSSHAREDIR:-"/usr/share/monkeysphere"} +export SYSSHAREDIR +. "${SYSSHAREDIR}/common" || exit 1 + +######################################################################## +# FUNCTIONS +######################################################################## usage() { -cat <<EOF >&2 + cat <<EOF >&2 usage: ssh -o ProxyCommand="$(basename $0) %h %p" ... EOF } +log() { + echo "$@" >&2 +} + +output_no_valid_key() { + local sshKeyOffered + local userID + local type + local validity + local keyid + local uidfpr + local usage + local sshKeyGPG + local tmpkey + local sshFingerprint + local gpgSigOut + + userID="ssh://${HOSTP}" + + log "-------------------- Monkeysphere warning -------------------" + log "Monkeysphere found OpenPGP keys for this hostname, but none had full validity." + + # retrieve the actual ssh key + sshKeyOffered=$(ssh-keyscan -t rsa -p "$PORT" "$HOST" 2>/dev/null | awk '{ print $2, $3 }') + # FIXME: should we do any checks for failed keyscans, eg. host not + # found? + + # get the gpg info for userid + gpgOut=$(gpg --list-key --fixed-list-mode --with-colon \ + --with-fingerprint --with-fingerprint \ + ="$userID" 2>/dev/null) + + # find all 'pub' and 'sub' lines in the gpg output, which each + # represent a retrieved key for the user ID + echo "$gpgOut" | cut -d: -f1,2,5,10,12 | \ + while IFS=: read -r type validity keyid uidfpr usage ; do + case $type in + 'pub'|'sub') + # get the ssh key of the gpg key + sshKeyGPG=$(gpg2ssh "$keyid") + + # if one of keys found matches the one offered by the + # host, then output info + if [ "$sshKeyGPG" = "$sshKeyOffered" ] ; then + log "An OpenPGP key matching the ssh key offered by the host was found:" + log + + # get the fingerprint of the ssh key + tmpkey=$(mktemp ${TMPDIR:-/tmp}/tmp.XXXXXXXXXX) + echo "$sshKeyGPG" > "$tmpkey" + sshFingerprint=$(ssh-keygen -l -f "$tmpkey" | \ + awk '{ print $2 }') + rm -rf "$tmpkey" + + # get the sigs for the matching key + gpgSigOut=$(gpg --check-sigs \ + --list-options show-uid-validity \ + "$keyid") + + # output the sigs, but only those on the user ID + # we are looking for + echo "$gpgSigOut" | awk ' +{ +if (match($0,"^pub")) { print; } +if (match($0,"^uid")) { ok=0; } +if (match($0,"^uid.*'$userID'$")) { ok=1; print; } +if (ok) { if (match($0,"^sig")) { print; } } +} +' >&2 + log + + # output the other user IDs for reference + if (echo "$gpgSigOut" | grep "^uid" | grep -v -q "$userID") ; then + log "Other user IDs on this key:" + echo "$gpgSigOut" | grep "^uid" | grep -v "$userID" >&2 + log + fi + + # output ssh fingerprint + log "RSA key fingerprint is ${sshFingerprint}." + + # this whole process is in a "while read" + # subshell. the only way to get information out + # of the subshell is to change the return code. + # therefore we return 1 here to indicate that a + # matching gpg key was found for the ssh key + # offered by the host + return 1 + fi + ;; + esac + done + + # if no key match was made (and the "while read" subshell returned + # 1) output how many keys were found + if (($? != 1)) ; then + log "None of the found keys matched the key offered by the host." + log "Run the following command for more info about the found keys:" + log "gpg --check-sigs --list-options show-uid-validity =${userID}" + # FIXME: should we do anything extra here if the retrieved + # host key is actually in the known_hosts file and the ssh + # connection will succeed? Should the user be warned? + # prompted? + fi + + log "-------------------- ssh continues below --------------------" +} + ######################################################################## # export the monkeysphere log level @@ -35,7 +152,7 @@ HOST="$1" PORT="$2" if [ -z "$HOST" ] ; then - echo "Host not specified." >&2 + log "Host not specified." usage exit 255 fi @@ -88,6 +205,39 @@ export MONKEYSPHERE_CHECK_KEYSERVER # update the known_hosts file for the host monkeysphere update-known_hosts "$HOSTP" +# output on depending on the return of the update-known_hosts +# subcommand, which is (ultimately) the return code of the +# update_known_hosts function in common +case $? in + 0) + # acceptable host key found so continue to ssh + true + ;; + 1) + # no hosts at all found so also continue (drop through to + # regular ssh host verification) + true + ;; + 2) + # at least one *bad* host key (and no good host keys) was + # found, so output some usefull information + output_no_valid_key + ;; + *) + # anything else drop through + true + ;; +esac + +# FIXME: what about the case where monkeysphere successfully finds a +# valid key for the host and adds it to the known_hosts file, but a +# different non-monkeysphere key for the host already exists in the +# known_hosts, and it is this non-ms key that is offered by the host? +# monkeysphere will succeed, and the ssh connection will succeed, and +# the user will be left with the impression that they are dealing with +# a OpenPGP/PKI host key when in fact they are not. should we use +# ssh-keyscan to compare the keys first? + # exec a netcat passthrough to host for the ssh connection if [ -z "$NO_CONNECT" ] ; then if (which nc 2>/dev/null >/dev/null); then |