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0515adceaa
passt/test/lib/setup
Stefano Brivio 0515adceaa passt, pasta: Namespace-based sandboxing, defer seccomp policy application 
To reach (at least) a conceptually equivalent security level as
implemented by --enable-sandbox in slirp4netns, we need to create a
new mount namespace and pivot_root() into a new (empty) mountpoint, so
that passt and pasta can't access any filesystem resource after
initialisation.

While at it, also detach IPC, PID (only for passt, to prevent
vulnerabilities based on the knowledge of a target PID), and UTS
namespaces.

With this approach, if we apply the seccomp filters right after the
configuration step, the number of allowed syscalls grows further. To
prevent this, defer the application of seccomp policies after the
initialisation phase, before the main loop, that's where we expect bad
things to happen, potentially. This way, we get back to 22 allowed
syscalls for passt and 34 for pasta, on x86_64.

While at it, move #syscalls notes to specific code paths wherever it
conceptually makes sense.

We have to open all the file handles we'll ever need before
sandboxing:

- the packet capture file can only be opened once, drop instance
  numbers from the default path and use the (pre-sandbox) PID instead

- /proc/net/tcp{,v6} and /proc/net/udp{,v6}, for automatic detection
  of bound ports in pasta mode, are now opened only once, before
  sandboxing, and their handles are stored in the execution context

- the UNIX domain socket for passt is also bound only once, before
  sandboxing: to reject clients after the first one, instead of
  closing the listening socket, keep it open, accept and immediately
  discard new connection if we already have a valid one

Clarify the (unchanged) behaviour for --netns-only in the man page.

To actually make passt and pasta processes run in a separate PID
namespace, we need to unshare(CLONE_NEWPID) before forking to
background (if configured to do so). Introduce a small daemon()
implementation, __daemon(), that additionally saves the PID file
before forking. While running in foreground, the process itself can't
move to a new PID namespace (a process can't change the notion of its
own PID): mention that in the man page.

For some reason, fork() in a detached PID namespace causes SIGTERM
and SIGQUIT to be ignored, even if the handler is still reported as
SIG_DFL: add a signal handler that just exits.

We can now drop most of the pasta_child_handler() implementation,
that took care of terminating all processes running in the same
namespace, if pasta started a shell: the shell itself is now the
init process in that namespace, and all children will terminate
once the init process exits.

Issuing 'echo $$' in a detached PID namespace won't return the
actual namespace PID as seen from the init namespace: adapt
demo and test setup scripts to reflect that.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2022-02-21 13:41:13 +01:00

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#!/bin/sh
#
# SPDX-License-Identifier: AGPL-3.0-or-later
#
# PASST - Plug A Simple Socket Transport
# for qemu/UNIX domain socket mode
#
# PASTA - Pack A Subtle Tap Abstraction
# for network namespace/tap device mode
#
# test/lib/setup - Set up and tear down passt and pasta environments
#
# Copyright (c) 2021 Red Hat GmbH
# Author: Stefano Brivio <sbrivio@redhat.com>
VCPUS="$( [ $(nproc) -ge 8 ] && echo 6 || echo $(( $(nproc) / 2 + 1 )) )"
__mem_kib="$(sed -n 's/MemTotal:[ ]*\([0-9]*\) kB/\1/p' /proc/meminfo)"
VMEM="$((${__mem_kib} / 1024 / 4))"
# setup_build() - Set up pane layout for build tests
setup_build() {
MODE=build
layout_host
}
# setup_passt() - Build guest initrd with mbuto, start qemu and passt
setup_passt() {
MODE=passt
layout_passt
__mbuto_dir="$(mktemp -d)"
pane_run GUEST "git -C ${__mbuto_dir} clone https://mbuto.lameexcu.se/mbuto/"
pane_wait GUEST
pane_run GUEST "${__mbuto_dir}/mbuto/mbuto -p passt -c lz4 -f mbuto.img"
pane_wait GUEST
rm -rf "${__mbuto_dir}"
# Ports:
#
# guest | host
# --------------|---------------------
# 10001 as server | forwarded to guest
# 10003 | as server
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/passt.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST "./passt ${__opts} -f -t 10001 -u 10001"
sleep 1
pane_run GUEST './qrap 5 kvm -m '${VMEM}' -cpu host -smp '${VCPUS} \
' -kernel ' "/boot/vmlinuz-$(uname -r)" \
' -initrd mbuto.img -nographic -serial stdio' \
' -nodefaults' \
' -append "console=ttyS0 mitigations=off apparmor=0 ' \
'virtio-net.napi_tx=1"' \
" -device virtio-net-pci,netdev=hostnet0,x-txburst=16384" \
" -netdev socket,fd=5,id=hostnet0"
pane_wait GUEST
}
# setup_pasta() - Create a network and user namespace, connect pasta to it
setup_pasta() {
MODE=pasta
layout_pasta
pane_run NS "unshare -rUn /bin/sh "
pane_wait NS
pane_run NS 'echo $$'
pane_wait NS
__pasta_pid="$(pane_parse NS)"
# Ports:
#
# ns | host
# ------------------|---------------------
# 10002 as server | spliced to ns
# 10003 spliced to init | as server
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/pasta.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST "./pasta ${__opts} -f -t 10002 -T 10003 -u 10002 -U 10003 ${__pasta_pid}"
sleep 1
}
# setup_passt_in_ns() - Set up namespace (with pasta), run qemu and passt into it
setup_passt_in_ns() {
MODE=passt_in_ns
layout_passt_in_pasta
# Ports:
#
# guest | ns | host
# -------------|--------------------|-----------------
# 10001 as server | forwarded to guest | spliced to ns
# 10002 | as server | spliced to ns
# 10003 | spliced to init | as server
# 10011 as server | forwarded to guest | spliced to ns
# 10012 | as server | spliced to ns
# 10013 | spliced to init | as server
#
# 10021 as server | forwarded to guest |
# 10031 as server | forwarded to guest |
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/pasta_with_passt.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
__pid_file="$(mktemp)"
pane_run PASST "./pasta ${__opts} -t 10001,10002,10011,10012 -T 10003,10013 -u 10001,10002,10011,10012 -U 10003,10013 -P ${__pid_file}"
sleep 1
pane_run PASST ''
pane_wait PASST
__pasta_pid="$(cat "${__pid_file}")"
__ns_pid="$(cat /proc/${__pasta_pid}/task/${__pasta_pid}/children | cut -f1 -d' ')"
rm "${__pid_file}"
pane_run GUEST "nsenter -t ${__ns_pid} -U -n --preserve-credentials"
pane_run NS "nsenter -t ${__ns_pid} -U -n --preserve-credentials"
pane_wait GUEST
pane_wait NS
pane_run NS "ip -j li sh | jq -rM '.[] | select(.link_type == \"ether\").ifname'"
pane_wait NS
__ifname="$(pane_parse NS)"
pane_run NS "/sbin/udhcpc -i ${__ifname}"
pane_wait NS
sleep 2
pane_run NS "/sbin/dhclient -6 ${__ifname}"
pane_wait NS
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/passt_in_pasta.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
#pane_run PASST "valgrind --max-stackframe=3000000 ./passt -f ${__opts} -t 10001,10011,10021,10031 -u 10001,10011,10021,10031"
pane_run PASST "./passt -f ${__opts} -t 10001,10011,10021,10031 -u 10001,10011,10021,10031"
sleep 1
pane_run GUEST './qrap 5 kvm -m '${VMEM}' -cpu host -smp '${VCPUS} \
' -kernel ' "/boot/vmlinuz-$(uname -r)" \
' -initrd mbuto.img -nographic -serial stdio' \
' -nodefaults' \
' -append "console=ttyS0 mitigations=off apparmor=0 ' \
'virtio-net.napi_tx=1"' \
" -device virtio-net-pci,netdev=hostnet0,x-txburst=524288" \
" -netdev socket,fd=5,id=hostnet0"
pane_wait GUEST
}
# setup_two_guests() - Set up two namespace, run qemu and passt in both of them
setup_two_guests() {
MODE=passt_in_ns
layout_two_guests
# Ports:
#
# guest #1 | guest #2 | ns #1 | ns #2 | host
# --------- |-----------|-----------|------------|------------
# 10001 as server | | to guest | to init | to ns #1
# 10002 | | as server | | to ns #1
# 10003 | | to init | to init | as server
# 10004 | as server | to init | to guest | to ns #2
# 10005 | | | as server | to ns #2
__pid1_file="$(mktemp)"
__pid2_file="$(mktemp)"
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/pasta_1.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST_1 "./pasta ${__opts} -P ${__pid1_file} -t 10001,10002 -T 10003,10004 -u 10001,10002 -U 10003,10004"
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/pasta_2.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST_2 "./pasta ${__opts} -P ${__pid2_file} -t 10004,10005 -T 10003,10001 -u 10004,10005 -U 10003,10001"
sleep 1
pane_run PASST_1 ''
pane_run PASST_2 ''
pane_wait PASST_1
pane_wait PASST_2
__pasta1_pid="$(cat "${__pid1_file}")"
__ns1_pid="$(cat /proc/${__pasta1_pid}/task/${__pasta1_pid}/children | cut -f1 -d' ')"
rm "${__pid1_file}"
__pasta2_pid="$(cat "${__pid2_file}")"
__ns2_pid="$(cat /proc/${__pasta2_pid}/task/${__pasta2_pid}/children | cut -f1 -d' ')"
rm "${__pid2_file}"
pane_run GUEST_1 "nsenter -t ${__ns1_pid} -U -n --preserve-credentials"
pane_run GUEST_2 "nsenter -t ${__ns2_pid} -U -n --preserve-credentials"
pane_run PASST_1 "ip -j li sh | jq -rM '.[] | select(.link_type == \"ether\").ifname'"
pane_wait PASST_1
__ifname="$(pane_parse PASST_1)"
pane_run GUEST_1 "/sbin/udhcpc -i ${__ifname}"
pane_run GUEST_2 "/sbin/udhcpc -i ${__ifname}"
pane_wait GUEST_1
pane_wait GUEST_2
sleep 2
pane_run GUEST_1 "/sbin/dhclient -6 ${__ifname}"
pane_run GUEST_2 "/sbin/dhclient -6 ${__ifname}"
pane_wait GUEST_1
pane_wait GUEST_2
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/passt_1.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST_1 "./passt -f ${__opts} -t 10001 -u 10001"
sleep 1
__opts=
[ ${PCAP} -eq 1 ] && __opts="${__opts} -p /tmp/passt_2.pcap"
[ ${DEBUG} -eq 1 ] && __opts="${__opts} -d"
pane_run PASST_2 "./passt -f ${__opts} -t 10004 -u 10004"
pane_run GUEST_2 'cp mbuto.img mbuto_2.img'
pane_wait GUEST_2
pane_run GUEST_1 './qrap 5 kvm -m '${VMEM}' -cpu host -smp '${VCPUS} \
' -kernel ' "/boot/vmlinuz-$(uname -r)" \
' -initrd mbuto.img -nographic -serial stdio' \
' -nodefaults' \
' -append "console=ttyS0 mitigations=off apparmor=0 ' \
'virtio-net.napi_tx=1"' \
" -device virtio-net-pci,netdev=hostnet0,x-txburst=16384" \
" -netdev socket,fd=5,id=hostnet0"
pane_run GUEST_2 './qrap 5 kvm -m '${VMEM}' -cpu host -smp '${VCPUS} \
' -kernel ' "/boot/vmlinuz-$(uname -r)" \
' -initrd mbuto_2.img -nographic -serial stdio' \
' -nodefaults' \
' -append "console=ttyS0 mitigations=off apparmor=0 ' \
'virtio-net.napi_tx=1"' \
" -device virtio-net-pci,netdev=hostnet0,x-txburst=16384" \
" -netdev socket,fd=5,id=hostnet0"
pane_wait GUEST_1
pane_wait GUEST_2
}
# teardown_passt() - Kill qemu and passt
teardown_passt() {
tmux send-keys -t ${PANE_PASST} "C-c"
pane_wait PASST
tmux send-keys -t ${PANE_GUEST} "C-c"
pane_wait GUEST
}
# teardown_passt() - Exit namespace, kill pasta process
teardown_pasta() {
tmux send-keys -t ${PANE_PASST} "C-c"
pane_wait PASST
tmux send-keys -t ${PANE_NS} "C-d"
pane_wait NS
}
# teardown_passt_in_ns() - Exit namespace, kill qemu, passt and pasta
teardown_passt_in_ns() {
tmux send-keys -t ${PANE_GUEST} "C-c"
pane_wait GUEST
tmux send-keys -t ${PANE_GUEST} "C-d"
tmux send-keys -t ${PANE_PASST} "C-c"
pane_wait PASST
tmux send-keys -t ${PANE_PASST} "C-d"
tmux send-keys -t ${PANE_NS} "C-d"
pane_wait GUEST
pane_wait NS
pane_wait PASST
}
# teardown_two_guests() - Exit namespaces, kill qemu processes, passt and pasta
teardown_two_guests() {
tmux send-keys -t ${PANE_GUEST_1} "C-c"
pane_wait GUEST_1
tmux send-keys -t ${PANE_GUEST_1} "C-d"
tmux send-keys -t ${PANE_GUEST_2} "C-c"
pane_wait GUEST_2
tmux send-keys -t ${PANE_GUEST_2} "C-d"
tmux send-keys -t ${PANE_PASST_1} "C-c"
pane_wait PASST_1
tmux send-keys -t ${PANE_PASST_1} "C-d"
tmux send-keys -t ${PANE_PASST_2} "C-c"
pane_wait PASST_2
tmux send-keys -t ${PANE_PASST_2} "C-d"
tmux send-keys -t ${PANE_NS_1} "C-d"
tmux send-keys -t ${PANE_NS_2} "C-d"
pane_wait GUEST_1
pane_wait GUEST_2
ns_1_wait
ns_2_wait
pane_wait PASST_1
pane_wait PASST_2
}
# teardown_demo_passt() - Exit namespace, kill qemu, passt and pasta
teardown_demo_passt() {
tmux send-keys -t ${PANE_GUEST} "C-c"
pane_wait GUEST
tmux send-keys -t ${PANE_GUEST} "C-d"
tmux send-keys -t ${PANE_HOST} "C-d"
tmux send-keys -t ${PANE_PASST} "C-c"
pane_wait PASST
tmux send-keys -t ${PANE_PASST} "C-d"
pane_wait GUEST
pane_wait HOST
pane_wait PASST
}
# teardown_demo_pasta() - Exit namespace from remaining pane
teardown_demo_pasta() {
tmux send-keys -t ${PANE_NS} "C-d"
pane_wait NS
}
# setup() - Run setup_*() functions
# $*: Suffix list of setup_*() functions to be called
setup() {
for arg do
eval setup_${arg}
done
}
# teardown() - Run teardown_*() functions
# $*: Suffix list of teardown_*() functions to be called
teardown() {
for arg do
eval teardown_${arg}
done
}
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