Bluetooth/Cellular PAN: IPv6 property path is too long

[TJ]

On 16.04 there are lots of warnings for paths generated under /proc/sys/net/ipv6/conf/ of the form:

NetworkManager[2043]: <error> [1516281647.5546] Failed asserting path component: "hfp/org/bluez/hci0/dev_2C_8A_72_15_A8_55"
NetworkManager[2043]: <warn> [1516281647.5546] IPv6 property path is too long: '/proc/sys/net/ipv6/conf/hfp/org/bluez/hci0/dev_2C_8A_72_15_A8_55/accept_ra'

These 2 messages occur for all of:

accept_ra
accept_ra_defrtr
accept_ra_pinfo
accept_ra_rtr_pref
disable_ipv6
hop_limit
use_tempaddr

In this case the device is a (currently disconnected) cellular phone:

bluez: BT device HTC One M8 (2C:8A:72:15:A8:55) added (DUN NAP)

---
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
CurrentDesktop: LXDE
DistroRelease: Ubuntu 16.04
EcryptfsInUse: Yes
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 # Include files from /etc/network/interfaces.d:
 source-directory /etc/network/interfaces.d
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=false
 WimaxEnabled=true
Package: network-manager 1.2.6-0ubuntu0.16.04.2
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 4.13.0-25.29~16.04.2-lowlatency 4.13.13
Tags: third-party-packages xenial
Uname: Linux 4.13.0-25-lowlatency x86_64
UpgradeStatus: Upgraded to xenial on 2017-09-17 (122 days ago)
UserGroups: adm audio cdrom dialout disk floppy libvirtd lp lpadmin lxd plugdev root sudo users video wireshark
_MarkForUpload: True
mtime.conffile..etc.dbus-1.system.d.nm-dispatcher.conf: 2015-11-04T09:44:08.042438
mtime.conffile..etc.dbus-1.system.d.nm-ofono.conf: 2015-11-04T09:44:08.042438
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.2.6 connected started full enabled enabled enabled enabled disabled

[TJ (tj)]

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[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. The issue you are reporting is an upstream one and it would be nice if somebody having it could send the bug to the developers of the software by following the instructions at https://wiki.ubuntu.com/Bugs/Upstream/GNOME. If you have done so, please tell us the number of the upstream bug (or the link), so we can add a bugwatch that will inform us about its status. Thanks in advance.

[TJ (tj)]

Seb:

This is a bug in the Ubuntu-only ofono patches where the interface name is being generated incorrectly.

"hfp/org/bluez/hci0/dev_2C_8A_72_15_A8_55" is not a valid interface name under "/proc/sys/net/ipv6/conf/"

$ ls /proc/sys/net/ipv6/conf/
all default enp0s29f7u5i6 enp2s0 lo lxcbr0 tun0 virbr0 virbr0-nic vlan99 wlp3s0

As I said in the initial report this is for a (currently disabled) remote bluetooth device providing (I presume) a PAN connection.

I think this is being attempted since in the dim-distant past I connected the PC over Bluetooth to the smartphone:

$ nmcli con show "HTC One M8 Network"

connection.id: HTC One M8 Network
connection.uuid: 01aea27a-7318-4d2f-b9ab-311654d836b9
connection.interface-name: --
connection.type: bluetooth
connection.autoconnect: no
connection.autoconnect-priority: 0
connection.timestamp: 0
connection.read-only: no
connection.permissions:
connection.zone: --
connection.master: --
connection.slave-type: --
connection.autoconnect-slaves: -1 (default)
connection.secondaries:
connection.gateway-ping-timeout: 0
connection.metered: unknown
connection.lldp: -1 (default)
ipv4.method: auto
ipv4.dns:
ipv4.dns-search:
ipv4.dns-options: (default)
ipv4.dns-priority: 0
ipv4.addresses:
ipv4.gateway: --
ipv4.routes:
ipv4.route-metric: -1
ipv4.ignore-auto-routes: no
ipv4.ignore-auto-dns: no
ipv4.dhcp-client-id: --
ipv4.dhcp-timeout: 0
ipv4.dhcp-send-hostname: yes
ipv4.dhcp-hostname: --
ipv4.dhcp-fqdn: --
ipv4.never-default: no
ipv4.may-fail: no
ipv4.dad-timeout: -1 (default)
ipv6.method: auto
ipv6.dns:
ipv6.dns-search:
ipv6.dns-options: (default)
ipv6.dns-priority: 0
ipv6.addresses:
ipv6.gateway: --
ipv6.routes:
ipv6.route-metric: -1
ipv6.ignore-auto-routes: no
ipv6.ignore-auto-dns: no
ipv6.never-default: no
ipv6.may-fail: yes
ipv6.ip6-privacy: -1 (unknown)
ipv6.addr-gen-mode: stable-privacy
ipv6.dhcp-send-hostname: yes
ipv6.dhcp-hostname: --
bluetooth.bdaddr: 2C:8A:72:15:A8:55
bluetooth.type: panu

[TJ (tj)]

/var/log/syslog extract showing bluetoothd/network-manager-ofono interaction.