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passt/test/demo/pasta
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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# 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/demo/pasta - Quick introduction to pasta
#
# Copyright (c) 2021 Red Hat GmbH
# Author: Stefano Brivio <sbrivio@redhat.com>
onlyfor pasta
say This is a short introduction to
em pasta
say .
nl
nl
sleep 3
say Let's fetch the source
sleep 1
tempdir TEMPDIR
host cd __TEMPDIR__
host git clone https://passt.top/passt
sleep 1
say and build it.
sleep 1
host cd passt
host make
sleep 1
nl
nl
say A quick look at the man page...
sleep 1
hostb man ./pasta.1
sleep 5
hostb /pasta
sleep 2
hostb n
sleep 2
hostb n
sleep 10
nl
say without PID, it will create a namespace.
sleep 3
passt cd __TEMPDIR__/passt
passtb ./pasta
sleep 3
nl
nl
say For convenience, let's enter this namespace
nl
say from another terminal.
sleep 3
ns pstree -p | grep pasta
nsout TARGET_PID pstree -p | grep pasta | sed -n 's/.*(\([0-9].*\))$/\1/p'
sleep 1
ns nsenter -t __TARGET_PID__ -U -n --preserve-credentials
sleep 5
nl
nl
say Now, we're ready to configure networking.
sleep 2
host q
nl
nl
ns ip li sh
sleep 3
say Let's configure IPv4 first...
sleep 2
ns dhclient
sleep 2
ns ip ad sh
sleep 5
nl
say SLAAC is already done, but we can also
nl
say get another address via DHCPv6.
sleep 3
ns dhclient -6
sleep 3
nl
nl
say Let's try to communicate between host and namespace
sleep 2
nl
say ...there's no need to configure port forwarding,
nl
say pasta detects bound ports and forwards them.
sleep 3
nsb nc -6 -l -p 31337
sleep 2
host echo "Hello from the host" | nc -N ::1 31337
sleep 5
nl
nl
say Now the other way around...
nl
say we can use a loopback address
sleep
hostb nc -l -p 31337
sleep 2
ns echo "Hello from the namespace" | nc -N 127.0.0.1 31337
sleep 5
nl
say or the address of the default gateway.
sleep 2
nsout GW ip -j -4 ro sh|jq -rM '.[] | select(.dst == "default").gateway'
sleep 5
hostb nc -l -p 31337
sleep 2
ns echo "Hello from the namespace" | nc -N __GW__ 31337
sleep 3
nl
nl
say UDP...
sleep 2
ns host -t A passt.top
sleep 3
say seems to work too.
sleep 3
nl
nl
em pasta
say can also take packet captures.
sleep 3
passt exit
sleep 2
temp TEMP
passtb ./pasta -p __TEMP__.pcap
sleep 2
passt
passt /sbin/dhclient
sleep 2
hostb tshark -r __TEMP__.pcap
sleep 5
nl
nl
say And there are tons of totally useless
sleep 1
bsp 14
say absolutely useful features
nl
say you can find described in the man page.
sleep 5
nl
nl
say Let's have a (quick!) look at performance
nl
say more in the "Performance" section below.
sleep 3
passt exit
passt CFLAGS="-g" make avx2
sleep 2
passtb perf record -g ./pasta
sleep 2
nsout TARGET_PID pstree -p | grep pasta | sed -n 's/.*(\([0-9].*\))$/\1/p'
sleep 1
ns nsenter -t __TARGET_PID__ -U -n --preserve-credentials
sleep 5
nl
nl
info Throughput in Gbps, latency in µs
th flow init>ns ns>init
set OPTS -P4 -l 1M -w 32M -i1 --pacing-timer 100000
tr TCP/IPv6 throughput
hostb sleep 10; iperf3 -c ::1 __OPTS__
nsout BW iperf3 -s1J | jq -rM ".end.sum_received.bits_per_second"
bw __BW__ 10.0 20.0
sleep 5
nsb sleep 10; iperf3 -c ::1 __OPTS__
hout BW iperf3 -s1J | jq -rM ".end.sum_received.bits_per_second"
bw __BW__ 10.0 20.0
tl TCP/IPv6 RR latency
nsb tcp_rr -6 --nolog
sleep 2
hout LAT tcp_rr --nolog -c -H ::1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
hostb tcp_rr -6 --nolog
sleep 2
nsout LAT tcp_rr --nolog -c -H ::1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
tl TCP/IPv6 CRR latency
nsb tcp_crr -6 --nolog
sleep 2
hout LAT tcp_crr --nolog -c -H ::1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
hostb tcp_crr -6 --nolog
sleep 2
nsout LAT tcp_crr --nolog -c -H ::1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
tr TCP/IPv4 throughput
hostb sleep 10; iperf3 -c 127.0.0.1 __OPTS__
nsout BW iperf3 -s1J | jq -rM ".end.sum_received.bits_per_second"
bw __BW__ 10.0 20.0
sleep 5
nsb sleep 10; iperf3 -c 127.0.0.1 __OPTS__
hout BW iperf3 -s1J | jq -rM ".end.sum_received.bits_per_second"
bw __BW__ 10.0 20.0
tl TCP/IPv4 RR latency
nsb tcp_rr -4 --nolog
sleep 2
hout LAT tcp_rr --nolog -c -H 127.0.0.1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
hostb tcp_rr -4 --nolog
sleep 2
nsout LAT tcp_rr --nolog -c -H 127.0.0.1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
tl TCP/IPv4 CRR latency
nsb tcp_crr -4 --nolog
sleep 2
hout LAT tcp_crr --nolog -c -H 127.0.0.1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
hostb tcp_crr -4 --nolog
sleep 2
nsout LAT tcp_crr --nolog -c -H 127.0.0.1 | sed -n 's/^throughput=\(.*\)/\1/p'
lat __LAT__ 1000 500
sleep 2
sleep 5
passt exit
sleep 2
killp PASST
killp HOST
sleep 2
ns cd __TEMPDIR__/passt
nsb perf report -g --max-stack 3
sleep 10
nl
nl
say I
em knew
say it.
em syscalls
say .
sleep 5
nl
nl
say Thanks for watching!
sleep 5
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