[snap] cannot pause video with bluetooth headset buttons any more (MPRIS denied by apparmor)

[Marius Gedminas]

On Ubuntu 19.04 I could press the button on my Bluetooth headset and the YouTube video playing in my Chromium would pause/resume. This no longer works in 19.10. What happens instead is I get an OSD popup with a NO ENTRY symbol (circle with a diagonal backslash) from gnome-shell.

I suspect the additional sandboxing of the snap package is the culprit.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: chromium-browser 76.0.3809.100-0ubuntu1~snap1
ProcVersionSignature: Ubuntu 5.3.0-13.14-generic 5.3.0
Uname: Linux 5.3.0-13-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
DRM.card0-DP-1:
 enabled: disabled
 dpms: Off
 status: disconnected
 edid-base64:
 modes:
DRM.card0-DP-2:
 enabled: disabled
 dpms: Off
 status: disconnected
 edid-base64:
 modes:
DRM.card0-HDMI-A-1:
 enabled: disabled
 dpms: Off
 status: disconnected
 edid-base64:
 modes:
DRM.card0-HDMI-A-2:
 enabled: disabled
 dpms: Off
 status: disconnected
 edid-base64:
 modes:
DRM.card0-eDP-1:
 enabled: enabled
 dpms: On
 status: connected
 edid-base64: AP///////wAGry1aAAAAAAAcAQSlHRF4Au6Vo1RMmSYPUFQAAAABAQEBAQEBAQEBAQEBAQEBtDeAoHA4PkA6KjUAJaUQAAAYAAAADwAAAAAAAAAAAAAAAAAgAAAA/gBBVU8KICAgICAgICAgAAAA/gBCMTMzSEFOMDUuQSAKAHA=
 modes: 1920x1080
Date: Mon Oct 21 15:04:13 2019
DiskUsage:
 Filesystem Type Size Used Avail Use% Mounted on
 /dev/nvme0n1p5 ext4 284G 208G 62G 78% /
 tmpfs tmpfs 7,7G 122M 7,6G 2% /dev/shm
 /dev/nvme0n1p5 ext4 284G 208G 62G 78% /
EcryptfsInUse: Yes
InstallationDate: Installed on 2019-06-12 (130 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
MachineType: LENOVO 20Q0CTO1WW
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-13-generic root=UUID=ad2946f7-6a38-471f-b7d1-779e8e9fd109 ro quiet splash vt.handoff=7
Snap.ChromeDriverVersion: ChromeDriver 77.0.3865.120 (416d6d8013e9adb6dd33b0c12e7614ff403d1a94-refs/branch-heads/3865@{#884})
Snap.ChromiumVersion: Chromium 77.0.3865.120 snap
SourcePackage: chromium-browser
UpgradeStatus: Upgraded to eoan on 2019-10-18 (2 days ago)
dmi.bios.date: 07/18/2019
dmi.bios.vendor: LENOVO
dmi.bios.version: N2JET73W (1.51 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20Q0CTO1WW
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN2JET73W(1.51):bd07/18/2019:svnLENOVO:pn20Q0CTO1WW:pvrThinkPadX390:rvnLENOVO:rn20Q0CTO1WW:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad X390
dmi.product.name: 20Q0CTO1WW
dmi.product.sku: LENOVO_MT_20Q0_BU_Think_FM_ThinkPad X390
dmi.product.version: ThinkPad X390
dmi.sys.vendor: LENOVO

[Marius Gedminas (mgedmin)]

I'm seeing this in journalctl -b -g chromium:

spal. 19 15:00:35 blynas dbus-daemon[4473]: apparmor="DENIED" operation="dbus_bind" bus="session" name="org.mpris.MediaPlayer2.chromium.instance5306" mask="bind" pid=5306 label="snap.chromium.chromium"
spal. 19 15:00:35 blynas chromium_chromium.desktop[4596]: [5306:5650:1019/150035.747129:ERROR:bus.cc(555)] Failed to get the ownership of org.mpris.MediaPlayer2.chromium.instance5306: Connection ":1.116" is not allowed to own the service "org.mpris.MediaPlayer2.chromium.instance5306" due to AppArmor policy

There's also

spal. 19 14:45:47 blynas kernel: audit: type=1107 audit(1571485547.156:75): pid=1458 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call" bus="system" path="/" interface="org.freedesktop.DBus.ObjectManager" member="GetManagedObjects" mask="send" name="org.bluez" pid=5306 label="snap.chromium.chromium" peer_pid=1496 peer_label="unconfined"
                                  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'

but I think it the bluetooth headset button works via MPRIS, rather than directly through bluez.

[Marius Gedminas (mgedmin)]

I've been googling, and it appears that Chromium should enable the mpris interface in the snapcraft YAML for this to work: https://snapcraft.io/docs/mpris-interface

Except if Chromium actually uses what looks like a dynamic part ("instance" + pid) in the dbus interface name, can it be made to work without patching Chromium's source?

[Olivier Tilloy (osomon)]

Confirmed, and adding the mpris slot fixes the issue.

[Olivier Tilloy (osomon)]

Fixed with https://git.launchpad.net/~chromium-team/chromium-browser/+git/snap-from-source/commit/?id=aca99f48134f58c912d6a573ca1233ac601754ed.

[Marius Gedminas (mgedmin)]

I can confirm that the fix works with chromium snap 78.0.3904.70 (rev 909).