The return value from mgmt_index_added() and mgmt_index_removed()
functions is never used. So do not pretend that returning an error
would actually be handled and just make both functions return void.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The helper function mgmt_valid_hdev() is more obfuscating the code
then it makes it easier to read. So intead of this helper, use the
direct check for BR/EDR device type.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The mgmt_new_settings() function was only needed to handle the
error case when re-enabling advertising failed. Since that is
now handled internally inside the management core, this function
is not needed anymore. So just remove it.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

When the all LE connections have been disconneted, then it is up to
the host to re-enable advertising at that point. To ensure that the
correct advertising parameters are used, force the usage of the
common helper to enable advertising.

The change just moves the manual enabling of advertising from the
event handler into the management core so that the helper can
be actually shared.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

Add constants for ADV_IND, ADV_DIRECT_IND, ADV_SCAN_IND and
ADV_NONCONN_IND advertising types.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

Add the basic HCI structure for building the LE advertising parameters
command.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The hci_amp_capable() function has only a single user inside the L2CAP
core. Instead of exporting the function, place it next to its user.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The AMP controller status constants need to be actually used to avoid
crypted hardcoded numbers.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The special AMP controller id 0 is reserved for the BR/EDR controller
that has the main link. It is a fixed value and so use a constant for
this throughout the code to make it more visible when the handling is
for the BR/EDR channel or when it is for the AMP channel.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

There are two defined HCI device types. One is for BR/EDR controllers
and the other is for AMP controllers. The HCI device type is not the
same as the AMP controller type. It just happens that currently the
defined types match, but that is not guaranteed.

Split the usage of AMP controller type into its own domain so that
it is possible to separate between BR/EDR controllers, 802.11 AMP
controllers and any other AMP technology that might be defined in
the future.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

Add the constants for BR/EDR and 802.11 AMP controller types.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The list of controllers can be counted ahead of time and inline
inside the AMP discover handling. There is no need to export such
a function at all.

In addition just count the AMP controller and only allocated space
for a single mandatory BR/EDR controller. No need to allocate more
space than needed.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

A function is needed so that the HCI event processing can ask the mgmt
code to emit a new settings event. This is necessary e.g. when the event
processing does updates to mgmt related states without any dependency of
actual mgmt commands.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

This flag is used to indicate whether we want to have advertising
enabled or not, so give it a more suitable name.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Slave Page Response Timeout event indicates to the Host that a
slave page response timeout has occurred in the BR/EDR Controller.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 110

"7.7.72 Slave Page Response Timeout Event [New Section]
...
Note: this event will be generated if the slave BR/EDR Controller
responds to a page but does not receive the master FHS packet
(see Baseband, Section 8.3.3) within pagerespTO.

Event Parameters: NONE"
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Synchronization Train Complete event indicates that the Start
Synchronization Train command has completed.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 103

"7.7.67 Synchronization Train Complete Event [New Section]
...

Event Parameters:

Status 0x00       Start Synchronization Train command completed
                  successfully.
       0x01-0xFF  Start Synchronization Train command failed.
                  See Part D, Error Codes, for error codes and
                  descriptions."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Start_Synchronization_Train command controls the Synchronization
Train functionality in the BR/EDR Controller.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 86

"7.1.51 Start Synchronization Train Command [New Section]
...
If connectionless slave broadcast mode is not enabled, the Command
Disallowed (0x0C) error code shall be returned. After receiving this
command and returning a Command Status event, the Baseband starts
attempting to send synchronization train packets containing information
related to the enabled Connectionless Slave Broadcast packet timing.

Note: The AFH_Channel_Map used in the synchronization train packets is
configured by the Set_AFH_Channel_Classification command and the local
channel classification in the BR/EDR Controller.

The synchronization train packets will be sent using the parameters
specified by the latest Write_Synchronization_Train_Parameters command.
The Synchronization Train will continue until synchronization_trainTO
slots (as specified in the last Write_Synchronization_Train command)
have passed or until the Host disables the Connectionless Slave Broadcast
logical transport."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

he Set_Connectionless_Slave_Broadcast command controls the
Connectionless Slave Broadcast functionality in the BR/EDR
Controller.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 78

"7.1.49 Set Connectionless Slave Broadcast Command [New Section]
...
The LT_ADDR indicated in the Set_Connectionless_Slave_Broadcast shall be
pre-allocated using the HCI_Set_Reserved_LT_ADDR command. If the
LT_ADDR has not been reserved, the Unknown Connection Identifier (0x02)
error code shall be returned. If the controller is unable to reserve
sufficient bandwidth for the requested activity, the Connection Rejected
Due to Limited Resources (0x0D) error code shall be returned.

The LPO_Allowed parameter informs the BR/EDR Controller whether it is
allowed to sleep.

The Packet_Type parameter specifies which packet types are allowed. The
Host shall either enable BR packet types only, or shall enable EDR and DM1
packet types only.

The Interval_Min and Interval_Max parameters specify the range from which
the BR/EDR Controller must select the Connectionless Slave Broadcast
Interval. The selected Interval is returned."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Write_Synchronization_Train_Parameters command configures
the Synchronization Train functionality in the BR/EDR Controller.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 97

"7.3.90 Write Synchronization Train Parameters Command [New Section]
...
Note: The AFH_Channel_Map used in the Synchronization Train packets is
configured by the Set_AFH_Channel_Classification command and the local
channel classification in the BR/EDR Controller.

Interval_Min and Interval_Max specify the allowed range of
Sync_Train_Interval. Refer to [Vol. 2], Part B, section 2.7.2 for
a detailed description of Sync_Train_Interval. The BR/EDR Controller shall
select an interval from this range and return it in Sync_Train_Interval.
If the Controller is unable to select a value from this range, it shall
return the Invalid HCI Command Parameters (0x12) error code.

Once started (via the Start_Synchronization_Train Command) the
Synchronization Train will continue until synchronization_trainTO slots have
passed or Connectionless Slave Broadcast has been disabled."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Set_Connectionless_Slave_Broadcast_Data command provides the
ability for the Host to set Connectionless Slave Broadcast data in
the BR/EDR Controller.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 93

"7.3.88 Set Connectionless Slave Broadcast Data Command [New Section]
...
If connectionless slave broadcast mode is disabled, this data shall be
kept by the BR/EDR Controller and used once connectionless slave broadcast
mode is enabled. If connectionless slave broadcast mode is enabled,
and this command is successful, this data will be sent starting with
the next Connectionless Slave Broadcast instant.

The Data_Length field may be zero, in which case no data needs to be
provided.

The Host may fragment the data using the Fragment field in the command. If
the combined length of the fragments exceeds the capacity of the largest
allowed packet size specified in the Set Connectionless Slave Broadcast
command, all fragments associated with the data being assembled shall be
discarded and the Invalid HCI Command Parameters error (0x12) shall be
returned."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Delete_Reserved_LT_ADDR command requests that the BR/EDR
Controller cancel the reservation for a specific LT_ADDR reserved for the
purposes of Connectionless Slave Broadcast.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 92

"7.3.87 Delete Reserved LT_ADDR Command [New Section]
...
If the LT_ADDR indicated in the LT_ADDR parameter is not reserved by the
BR/EDR Controller, it shall return the Unknown Connection Identifier (0x02)
error code.
If connectionless slave broadcast mode is still active, then the Controller
shall return the Command Disallowed (0x0C) error code."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

The Set_Reserved_LT_ADDR command allows the host to request that the
BR/EDR Controller reserve a specific LT_ADDR for Connectionless Slave
Broadcast.

The Core Spec Addendum 4 adds this command in part B Connectionless
Slave Broadcast.

Bluetooth Core Specification Addendum 4 - Page 90

"7.3.86 Set Reserved LT_ADDR Command [New Section]
...
If the LT_ADDR indicated in the LT_ADDR parameter is already in use by the
BR/EDR Controller, it shall return the ACL Connection Already Exists (0x0B)
error code. If the LT_ADDR indicated in the LT_ADDR parameter is out of
range, the controller shall return the Invalid HCI Command Parameters (0x12)
error code. If the command succeeds, then the reserved LT_ADDR shall be
used when issuing subsequent Set Connectionless Slave Broadcast Data and
Set Connectionless Slave Broadcast commands.
To ensure that the reserved LT_ADDR is not already allocated, it is
recommended that this command be issued at some point after HCI_Reset is
issued but before page scanning is enabled or paging is initiated."
Signed-off-by: NDohyun Pyun <dh79.pyun@samsung.com>
Signed-off-by: NC S Bhargava <cs.bhargava@samsung.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

On dual-mode BR/EDR/LE and LE only controllers it is possible
to configure a random address. There are two types or random
addresses, one is static and the other private. Since the
random private addresses require special privacy feature to
be supported, the configuration of these two are kept separate.

This command allows for setting the static random address. It is
only supported on controllers with LE support. The static random
address is suppose to be valid for the lifetime of the controller
or at least until the next power cycle. To ensure such behavior,
setting of the address is limited to when the controller is
powered off.

The special BDADDR_ANY address (00:00:00:00:00:00) can be used to
disable the static address. This is also the default value.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

This patch introduces a new mgmt command for enabling/disabling BR/EDR
functionality. This can be convenient when one wants to make a dual-mode
controller behave like a single-mode one. The command is only available
for dual-mode controllers and requires that LE is enabled before using
it. The BR/EDR setting can be enabled at any point, however disabling it
requires the controller to be powered off (otherwise a "rejected"
response will be sent).

Disabling the BR/EDR setting will automatically disable all other BR/EDR
related settings.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

To allow treating dual-mode (BR/EDR/LE) controllers as single-mode ones
(LE-only) we want to introduce a new HCI_BREDR_ENABLED flag to track
whether BR/EDR is enabled or not (previously we simply looked at the
feature bit with lmp_bredr_enabled).

This patch add the new flag and updates the relevant places to test
against it instead of using lmp_bredr_enabled. The flag is by default
enabled when registering an adapter and only cleared if necessary once
the local features have been read during the HCI init procedure.

We cannot completely block BR/EDR usage in case user space uses raw HCI
sockets but the patch tries to block this in places where possible, such
as the various BR/EDR specific ioctls.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

Hiding the Bluetooth high speed support behind a module parameter is
not really useful. This can be enabled and disabled at runtime via
the management interface. This also has the advantage that this can
now be changed per controller and not just global.

This patch removes the module parameter and exposes the high speed
setting of the management interface to all controllers.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

The BDADDR_LOCAL is a relict from userspace and has never been used
within the kernel. So remove that constant and replace it with a new
BDADDR_NONE that is similar to HCI_DEV_NONE with all bits set.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>

This patch adds a new mgmt command for enabling and disabling
LE advertising. The command depends on the LE setting being enabled
first and will return a "rejected" response otherwise. The patch also
adds safeguards so that there will ever only be one set_le or
set_advertising command pending per adapter.

The response handling and new_settings event sending is done in an
asynchronous request callback, meaning raw HCI access from user space to
enable advertising (e.g. hciconfig leadv) will not trigger the
new_settings event. This is intentional since trying to support mixed
raw HCI and mgmt access would mean adding extra state tracking or new
helper functions, essentially negating the benefit of using the
asynchronous request framework. The HCI_LE_ENABLED and HCI_LE_PERIPHERAL
flags however are updated correctly even with raw HCI access so this
will not completely break subsequent access over mgmt.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch adds a new mgmt setting for LE advertising and hooks up the
necessary places in the mgmt code to operate on the HCI_LE_PERIPHERAL
flag (which corresponds to this setting). This patch does not yet add
any new command for enabling the setting - that is left for a subsequent
patch.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch updates the code to use an asynchronous request for handling
the enabling and disabling of LE support. This refactoring is necessary
as a preparation for adding advertising support, since when LE is
disabled we should also disable advertising, and the cleanest way to do
this is to perform the two respective HCI commands in the same
asynchronous request.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

For those controller that support the HCI_Set_Event_Mask_Page_2 command
we should include it in the init sequence. This patch implements sending
of the command and enables the events in it based on supported features
(currently only CSB is checked).
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch adds support for reading the synchronization train parameters
for controllers that support the feature. Since the feature is
detectable through the local features page 2, which is retreived only in
stage 3 of the HCI init sequence, there is no other option than to add a
fourth stage to the init sequence.

For now the patch doesn't yet add storing of the parameters, but it is
nevertheless convenient to have around to see what kind of parameters
various controllers use by default (analyzable e.g. with the btmon user
space tool).
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

In the case of blocking sockets we should not proceed with sendmsg() if
the socket has the BT_SK_SUSPEND flag set. So far the code was only
ensuring that POLLOUT doesn't get set for non-blocking sockets using
poll() but there was no code in place to ensure that blocking sockets do
the right thing when writing to them.

This patch adds a new bt_sock_wait_ready helper function to sleep in the
sendmsg call if the BT_SK_SUSPEND flag is set, and wake up as soon as it
is unset. It also updates the L2CAP and RFCOMM sendmsg callbacks to take
advantage of this new helper function.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

The struct for HCI_Set_Event_Mask is never used. Instead a local 8-byte
array is used for sending this command. Therefore, remove the
unnecessary struct definition.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This makes it more convenient to check for rfkill (no need to check for
dev->rfkill before calling rfkill_blocked()) and also avoids potential
races if the RFKILL state needs to be checked from within the rfkill
callback.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Cc: stable@vger.kernel.org
Acked-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch introcuces a new HCI socket channel that allows user
applications to take control over a specific HCI device. The application
gains exclusive access to this device and forces the kernel to stay away
and not manage it. In case of the management interface it will actually
hide the device.

Such operation is useful for security testing tools that need to operate
underneath the Bluetooth stack and need full control over a device. The
advantage here is that the kernel still provides the service of hardware
abstraction and HCI level access. The use of Bluetooth drivers for
hardware access also means that sniffing tools like btmon or hcidump
are still working and the whole set of transaction can be traced with
existing tools.

With the new channel it is possible to send HCI commands, ACL and SCO
data packets and receive HCI events, ACL and SCO packets from the
device. The format follows the well established H:4 protocol.

The new HCI user channel can only be established when a device has been
through its setup routine and is currently powered down. This is
enforced to not cause any problems with current operations. In addition
only one user channel per HCI device is allowed. It is exclusive access
for one user application. Access to this channel is limited to process
with CAP_NET_RAW capability.

Using this new facility does not require any external library or special
ioctl or socket filters. Just create the socket and bind it. After that
the file descriptor is ready to speak H:4 protocol.

        struct sockaddr_hci addr;
        int fd;

        fd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);

        memset(&addr, 0, sizeof(addr));
        addr.hci_family = AF_BLUETOOTH;
        addr.hci_dev = 0;
        addr.hci_channel = HCI_CHANNEL_USER;

        bind(fd, (struct sockaddr *) &addr, sizeof(addr));

The example shows on how to create a user channel for hci0 device. Error
handling has been left out of the example. However with the limitations
mentioned above it is advised to handle errors. Binding of the user
cahnnel socket can fail for various reasons. Specifically if the device
is currently activated by BlueZ or if the access permissions are not
present.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch introduces a new user channel flag that allows to give full
control of a HCI device to a user application. The kernel will stay away
from the device and does not allow any further modifications of the
device states.

The existing raw flag is not used since it has a bit of unclear meaning
due to its legacy. Using a new flag makes the code clearer.

A device with the user channel flag set can still be enumerate using the
legacy API, but it does not longer enumerate using the new management
interface used by BlueZ 5 and beyond. This is intentional to not confuse
users of modern systems.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

This patch adds two more ndo ops: ndo_add_rx_vxlan_port() and
ndo_del_rx_vxlan_port().

Drivers can get notifications through the above functions about changes
of the UDP listening port of VXLAN. Also, when physical ports come up,
now they can call vxlan_get_rx_port() in order to obtain the port number(s)
of the existing VXLAN interface in case they already up before them.

This information about the listening UDP port would be used for VXLAN
related offloads.

A big thank you to John Fastabend (john.r.fastabend@intel.com) for his
input and his suggestions on this patch set.

CC: John Fastabend <john.r.fastabend@intel.com>
CC: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NJoseph Gasparakis <joseph.gasparakis@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Get rid of MLDV2_MRC and use our new macros for mantisse and
exponent to calculate Maximum Response Delay out of the Maximum
Response Code.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

i) RFC3810, 9.2. Query Interval [QI] says:

   The Query Interval variable denotes the interval between General
   Queries sent by the Querier. Default value: 125 seconds. [...]

ii) RFC3810, 9.3. Query Response Interval [QRI] says:

  The Maximum Response Delay used to calculate the Maximum Response
  Code inserted into the periodic General Queries. Default value:
  10000 (10 seconds) [...] The number of seconds represented by the
  [Query Response Interval] must be less than the [Query Interval].

iii) RFC3810, 9.12. Older Version Querier Present Timeout [OVQPT] says:

  The Older Version Querier Present Timeout is the time-out for
  transitioning a host back to MLDv2 Host Compatibility Mode. When an
  MLDv1 query is received, MLDv2 hosts set their Older Version Querier
  Present Timer to [Older Version Querier Present Timeout].

  This value MUST be ([Robustness Variable] times (the [Query Interval]
  in the last Query received)) plus ([Query Response Interval]).

Hence, on *default* the timeout results in:

  [RV] = 2, [QI] = 125sec, [QRI] = 10sec
  [OVQPT] = [RV] * [QI] + [QRI] = 260sec

Having that said, we currently calculate [OVQPT] (here given as 'switchback'
variable) as ...

  switchback = (idev->mc_qrv + 1) * max_delay

RFC3810, 9.12. says "the [Query Interval] in the last Query received". In
section "9.14. Configuring timers", it is said:

  This section is meant to provide advice to network administrators on
  how to tune these settings to their network. Ambitious router
  implementations might tune these settings dynamically based upon
  changing characteristics of the network. [...]

iv) RFC38010, 9.14.2. Query Interval:

  The overall level of periodic MLD traffic is inversely proportional
  to the Query Interval. A longer Query Interval results in a lower
  overall level of MLD traffic. The value of the Query Interval MUST
  be equal to or greater than the Maximum Response Delay used to
  calculate the Maximum Response Code inserted in General Query
  messages.

I assume that was why switchback is calculated as is (3 * max_delay), although
this setting seems to be meant for routers only to configure their [QI]
interval for non-default intervals. So usage here like this is clearly wrong.

Concluding, the current behaviour in IPv6's multicast code is not conform
to the RFC as switch back is calculated wrongly. That is, it has a too small
value, so MLDv2 hosts switch back again to MLDv2 way too early, i.e. ~30secs
instead of ~260secs on default.

Hence, introduce necessary helper functions and fix this up properly as it
should be.

Introduced in 06da92283 ("[IPV6]: Add MLDv2 support."). Credits to Hannes
Frederic Sowa who also had a hand in this as well. Also thanks to Hangbin Liu
who did initial testing.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: David Stevens <dlstevens@us.ibm.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>