Re: [PATCH wpan-next 04/11] mac802154: Handle associating

Alexander Aring
2023-07-04T11:35:19Z

Hi,

On Sat, Jun 3, 2023 at 6:09 AM Alexander Aring <aahringo@redhat.com> wrote:
>
> Hi,
>
> On Thu, Jun 1, 2023 at 11:50 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >
> > Joining a PAN officially goes by associating with a coordinator. This
> > coordinator may have been discovered thanks to the beacons it sent in
> > the past. Add support to the MAC layer for these associations, which
> > require:
> > - Sending an association request
> > - Receiving an association response
> >
> > The association response contains the association status, eventually a
> > reason if the association was unsuccessful, and finally a short address
> > that we should use for intra-PAN communication from now on, if we
> > required one (which is the default, and not yet configurable).
> >
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> > include/linux/ieee802154.h | 1 +
> > include/net/cfg802154.h | 1 +
> > include/net/ieee802154_netdev.h | 5 ++
> > net/ieee802154/core.c | 14 ++++
> > net/mac802154/cfg.c | 72 ++++++++++++++++++
> > net/mac802154/ieee802154_i.h | 19 +++++
> > net/mac802154/main.c | 2 +
> > net/mac802154/rx.c | 9 +++
> > net/mac802154/scan.c | 127 ++++++++++++++++++++++++++++++++
> > 9 files changed, 250 insertions(+)
> >
> > diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
> > index 140f61ec0f5f..c72bd76cac1b 100644
> > --- a/include/linux/ieee802154.h
> > +++ b/include/linux/ieee802154.h
> > @@ -37,6 +37,7 @@
> > IEEE802154_FCS_LEN)
> >
> > #define IEEE802154_PAN_ID_BROADCAST 0xffff
> > +#define IEEE802154_ADDR_LONG_BROADCAST 0xffffffffffffffffULL
> > #define IEEE802154_ADDR_SHORT_BROADCAST 0xffff
> > #define IEEE802154_ADDR_SHORT_UNSPEC 0xfffe
> >
> > diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
> > index 3b9d65455b9a..dd0964d351cd 100644
> > --- a/include/net/cfg802154.h
> > +++ b/include/net/cfg802154.h
> > @@ -502,6 +502,7 @@ struct wpan_dev {
> > struct mutex association_lock;
> > struct ieee802154_pan_device *parent;
> > struct list_head children;
> > + unsigned int association_generation;
> > };
> >
> > #define to_phy(_dev) container_of(_dev, struct wpan_phy, dev)
> > diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
> > index ca8c827d0d7f..e26ffd079556 100644
> > --- a/include/net/ieee802154_netdev.h
> > +++ b/include/net/ieee802154_netdev.h
> > @@ -149,6 +149,11 @@ struct ieee802154_assoc_req_pl {
> > #endif
> > } __packed;
> >
> > +struct ieee802154_assoc_resp_pl {
> > + __le16 short_addr;
> > + u8 status;
> > +} __packed;
> > +
> > enum ieee802154_frame_version {
> > IEEE802154_2003_STD,
> > IEEE802154_2006_STD,
> > diff --git a/net/ieee802154/core.c b/net/ieee802154/core.c
> > index cd69bdbfd59f..8bf01bb7e858 100644
> > --- a/net/ieee802154/core.c
> > +++ b/net/ieee802154/core.c
> > @@ -198,6 +198,18 @@ void wpan_phy_free(struct wpan_phy *phy)
> > }
> > EXPORT_SYMBOL(wpan_phy_free);
> >
> > +static void cfg802154_free_peer_structures(struct wpan_dev *wpan_dev)
> > +{
> > + mutex_lock(&wpan_dev->association_lock);
> > +
> > + if (wpan_dev->parent)
> > + kfree(wpan_dev->parent);
> > +
> > + wpan_dev->association_generation++;
> > +
> > + mutex_unlock(&wpan_dev->association_lock);
> > +}
> > +
> > int cfg802154_switch_netns(struct cfg802154_registered_device *rdev,
> > struct net *net)
> > {
> > @@ -293,6 +305,8 @@ static int cfg802154_netdev_notifier_call(struct notifier_block *nb,
> > rdev->opencount++;
> > break;
> > case NETDEV_UNREGISTER:
> > + cfg802154_free_peer_structures(wpan_dev);
> > +
>
> I think the comment below is not relevant here, but I have also no
> idea if this is still the case.
>
> > /* It is possible to get NETDEV_UNREGISTER
> > * multiple times. To detect that, check
> > * that the interface is still on the list
> > diff --git a/net/mac802154/cfg.c b/net/mac802154/cfg.c
> > index 5c3cb019f751..89112d2bcee7 100644
> > --- a/net/mac802154/cfg.c
> > +++ b/net/mac802154/cfg.c
> > @@ -315,6 +315,77 @@ static int mac802154_stop_beacons(struct wpan_phy *wpan_phy,
> > return mac802154_stop_beacons_locked(local, sdata);
> > }
> >
> > +static int mac802154_associate(struct wpan_phy *wpan_phy,
> > + struct wpan_dev *wpan_dev,
> > + struct ieee802154_addr *coord)
> > +{
> > + struct ieee802154_local *local = wpan_phy_priv(wpan_phy);
> > + u64 ceaddr = swab64((__force u64)coord->extended_addr);
> > + struct ieee802154_sub_if_data *sdata;
> > + struct ieee802154_pan_device *parent;
> > + __le16 short_addr;
> > + int ret;
> > +
> > + ASSERT_RTNL();
> > +
> > + sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(wpan_dev);
> > +
> > + if (wpan_dev->parent) {
> > + dev_err(&sdata->dev->dev,
> > + "Device %8phC is already associated\n", &ceaddr);
> > + return -EPERM;
> > + }
> > +
> > + parent = kzalloc(sizeof(*parent), GFP_KERNEL);
> > + if (!parent)
> > + return -ENOMEM;
> > +
> > + parent->pan_id = coord->pan_id;
> > + parent->mode = coord->mode;
> > + if (parent->mode == IEEE802154_SHORT_ADDRESSING) {
> > + parent->short_addr = coord->short_addr;
> > + parent->extended_addr = cpu_to_le64(IEEE802154_ADDR_LONG_BROADCAST);
>
> There is no IEEE802154_ADDR_LONG_BROADCAST (extended address) address.
> The broadcast address is always a short address 0xffff. (Talkin about
> destination addresses).
>
> Just to clarify we can have here two different types/length of mac
> addresses being used, whereas the extended address is always present.
> We have the monitor interface set to an invalid extended address
> 0x0...0 (talking about source address) which is a reserved EUI64 (what
> long/extended address is) address, 0xffff...ffff is also being
> reserved. Monitors get their address from the socket interface.
>
> If there is a parent, an extended address is always present and known.

I want to weaken this, we can also have only the short address of the
neighbor. But it depends on assoc/deassoc, I would think the extended
address should be known. If you look on air and make per neighbor
stats... you can see a neighbor with either a short or extended
address being used. Map them to one neighbor if using a short address
is only possible if you know the mapping... (but this is so far I see
not the case here).

We need some kind of policy here, but with assoc/deassoc we should
always know this mapping.

- Alex