Merge ~morphis/snappy-hwe-snaps/+git/pulseaudio:feature/disallow-module-loading into ~snappy-hwe-team/snappy-hwe-snaps/+git/pulseaudio:master

[Simon Fels]

Disallow module loading as recommended by upstream

Upstream recommends disabling module loading when running pulseaudio
in system mode to prevent users from loading malicious code into the
daemon.

[Jim Hodapp (jhodapp)]

Looks very good, thanks for being proactive on this.

review: Approve (code)

[System Enablement Bot (system-enablement-ci-bot)]

PASSED: Continuous integration, rev:300690f4c7d1d77364d120a4530f10b0d8c77add
https://jenkins.canonical.com/system-enablement/job/generic-build-snap/637/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/system-enablement/job/generic-run-snap-spread-tests/356
    None: https://jenkins.canonical.com/system-enablement/job/generic-update-snap-mp/545/console

Click here to trigger a rebuild:
https://jenkins.canonical.com/system-enablement/job/generic-build-snap/637/rebuild

review: Approve (continuous-integration)

[System Enablement Bot (system-enablement-ci-bot)]

PASSED: Continuous integration, rev:300690f4c7d1d77364d120a4530f10b0d8c77add
https://jenkins.canonical.com/system-enablement/job/generic-build-snap/642/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/system-enablement/job/generic-run-snap-spread-tests/360
    None: https://jenkins.canonical.com/system-enablement/job/generic-update-snap-mp/550/console

Click here to trigger a rebuild:
https://jenkins.canonical.com/system-enablement/job/generic-build-snap/642/rebuild

review: Approve (continuous-integration)

diff --git a/bin/pulseaudio b/bin/pulseaudio
index d9fb85f..8e23f97 100755
--- a/bin/pulseaudio
+++ b/bin/pulseaudio
@@ -15,12 +15,13 @@ EXTRA_ARGS=
 
 if [ -e $SNAP_DATA/config/debug ] ; then
     EXTRA_ARGS="$EXTRA_ARGS -vvvv"
-	export LIBASOUND_DEBUG=1
+    export LIBASOUND_DEBUG=1
 fi
 
 $SNAP/usr/bin/pulseaudio \
     --exit-idle-time=-1 \
     --disallow-exit=yes \
+    --disallow-module-loading \
     --system \
     -F $SNAP/etc/pulse/default.pa \
     -p $SNAP/usr/lib/pulse-8.0/modules \
diff --git a/tests/main/module-loading-disabled/task.yaml b/tests/main/module-loading-disabled/task.yaml
new file mode 100644
index 0000000..39798f8
--- /dev/null
+++ b/tests/main/module-loading-disabled/task.yaml
@@ -0,0 +1,8 @@
+summary: Verify module loading is disabled
+
+description: |
+    As we're running pulseaudio in system mode (see https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/SystemWide/)
+    for more details we have module loading disabled to prevent any client from loading malicious code into the daemon.
+
+execute: |
+    ! /snap/bin/pulseaudio.pactl load-module module-null-sink