[CRIU] [PATCH 1/2] p.haul: p.haul-ssh

[Ruslan Kuprieiev]

Currently we have such security holes:

1) All p.haul traffic goes without any encryption, which is
not safe at all, cosidering that attacker can easily peek memory pages
of migrating process.

2) p.haul-service binds to 0.0.0.0 and is accesible from the outside
for anyone who is trying to connect to it. So attacket can easily connect
to p.haul-service and migrate some malicious process to the server.

Lets solve that by using ssh wrapper for p.haul. It creates ssh tunnel
and transmits all p.haul traffic through encrypted channel.
It also allows user to optionally use built-in ssh compression, which
is useful when connection is very slow, but probably will only slow down
things on fast networks. Using ssh also gives us an ability to let our
wrapper start p.haul-service on dst(on 127.0.0.1, so it is not directly
accesible from the outer web) automatically, without having us to
start it in advance. Also, ssh allows us to solve keys\certificates
management problem in a very common way that is familiar to any system
administrator.

So, to migrate, lets say, a task with pid PID to dsthost, you need to
execute a single command:
$ p.haul-ssh pid $PID dsthost

Signed-off-by: Ruslan Kuprieiev <kupruser at gmail.com>
---
 p.haul-ssh | 127 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100755 p.haul-ssh

diff --git a/p.haul-ssh b/p.haul-ssh
new file mode 100755
index 0000000..0971305
--- /dev/null
+++ b/p.haul-ssh
@@ -0,0 +1,127 @@
+#!/usr/bin/bash
+
+set -e
+
+# This script is a p.haul wrapper that allows to migrate process
+# using ssh tunnel for transferring data and without having to
+# start p.haul-service in advance.
+#
+# This script performs folowing actions:
+# 1) Launch p.haul-service on the remote and bind it to localhost:REM_PORT
+# 2) Parse cmdline options to extract ssh* opts and change
+#    p.haul opts appropriately, so p.haul will connect to
+#    localhost:LOC_PORT, that will be followed to the remote
+#    through the ssh tunnel.
+# 3) Establish ssh tunnel localhost:LOC_PORT->SSH->localhost:REM_PORT.
+# 4) Launch p.haul to start migration.
+
+TUNNEL_FLAGS="-o ExitOnForwardFailure=yes -fN "
+SERVER_FLAGS="-ttfM "
+LOC_PORT=54321
+REM_PORT=12345
+PORT=22
+USER="$(whoami)"
+REMOTE=""
+LOG="/tmp/phs.log"
+
+PH_EXEC="p.haul"
+PH_OPTS=()
+
+PHS_EXEC="p.haul-service"
+PHS_OPTS=()
+
+usage=\
+"SSH wrapper for p.haul\n\
+Usage: p.haul-ssh [SSH_OPTIONS] [PHAUL_OPTIONS]
+\n\
+SSH options:\n\
+  --ssh-compression   Use compression in ssh tunnel\n\
+  --ssh-username      Remote username (current user by default)\n\
+  --ssh-loc-port      Local port to use for forwarding (${LOC_PORT} by default)\n\
+  --ssh-port          SSH port (${PORT} by default)\n\
+  --ssh-log           Logfile for service log\n\
+  --ssh-ph-exec       Path to p.haul executable\n\
+  --ssh-phs-exec      Path to p.haul-service executable on the remote machine\n\
+  --help              Print this messange\n\
+\n\
+See p.haul --help for PHAUL_OPTIONS\n"
+
+while [ "$1" != "" ]; do
+	case $1 in
+	"--ssh-compression")
+		SERVER_FLAGS="${SERVER_FLAGS} -C"
+		TUNNEL_FLAGS="${TUNNEL_FLAGS} -C"
+		;;
+	"--ssh-username")
+		shift
+		USER=$1
+		;;
+	"--ssh-loc-port")
+		shift
+		LOC_PORT=$1
+		;;
+	"--port")
+		# Extract --port option(if present).
+		# --port LOC_PORT is added below.
+		shift
+		REM_PORT=$1
+		;;
+	"--ssh-ph-exec")
+		shift
+		PH_EXEC=$1
+		;;
+	"--ssh-phs-exec")
+		shift
+		PHS_EXEC=$1
+		;;
+	"--ssh-port")
+		shift
+		PORT=$1
+		;;
+	"--ssh-log")
+		shift
+		LOG=$1
+		;;
+	"--help")
+		printf "${usage}"
+		exit 0
+		;;
+	*)
+		PH_OPTS+=($1)
+		;;
+	esac
+	shift
+done
+
+# Replace p.haul positional "to" option with 127.0.0.1.
+REMOTE=${PH_OPTS[2]}
+PH_OPTS[2]="127.0.0.1"
+
+# Tell p.haul to connect to the local port
+PH_OPTS+=("--port ${LOC_PORT}")
+
+# Tell p.haul-service to bind on localhost, so it is not directly accesible
+# from the outer web.
+PHS_OPTS+=("--bind-port ${REM_PORT}")
+PHS_OPTS+=("--bind-addr \"127.0.0.1\"")
+
+# Use ssh multiplexing to speedup establishing additional ssh sessions and
+# to get control over all of them.
+CTL_SK="~/ph_ssh_${USER}_${REMOTE}_${PORT}"
+SSH_BASE="ssh -p ${PORT} ${USER}@${REMOTE} -S ${CTL_SK}"
+
+# Trap EXIT to stop ssh connection(i.e. all ssh sessions) on both normal
+# and error(see "set -e" above) exits.
+trap '${SSH_BASE} -S ${CTL_SK} -O exit &> /dev/null' EXIT
+
+echo "Start p.haul-service"
+${SSH_BASE} ${SERVER_FLAGS} ${PHS_EXEC} ${PHS_OPTS[@]} &> ${LOG} < /dev/null
+echo "Done"
+
+echo "Start ssh tunnel"
+${SSH_BASE} ${TUNNEL_FLAGS} -L ${LOC_PORT}:localhost:${REM_PORT}
+echo "Done"
+
+echo "Launch p.haul"
+${PH_EXEC} ${PH_OPTS[@]}
+echo "Done"
-- 
1.9.3