Hi Alexander,
aahringo@xxxxxxxxxx wrote on Tue, 23 Aug 2022 08:33:30 -0400:
> Hi,
>
> On Fri, Aug 19, 2022 at 1:11 PM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> >
> > Hi Alexander,
> >
> > aahringo@xxxxxxxxxx wrote on Tue, 5 Jul 2022 21:51:02 -0400:
> >
> > > Hi,
> > >
> > > On Fri, Jul 1, 2022 at 10:36 AM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> > > >
> > > > As a first strep in introducing proper PAN management and association,
> > > > we need to be able to create coordinator interfaces which might act as
> > > > coordinator or PAN coordinator.
> > > >
> > > > Hence, let's add the minimum support to allow the creation of these
> > > > interfaces. This might be restrained and improved later.
> > > >
> > > > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > > > ---
> > > > net/mac802154/iface.c | 14 ++++++++------
> > > > net/mac802154/rx.c | 2 +-
> > > > 2 files changed, 9 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
> > > > index 500ed1b81250..7ac0c5685d3f 100644
> > > > --- a/net/mac802154/iface.c
> > > > +++ b/net/mac802154/iface.c
> > > > @@ -273,13 +273,13 @@ ieee802154_check_concurrent_iface(struct ieee802154_sub_if_data *sdata,
> > > > if (nsdata != sdata && ieee802154_sdata_running(nsdata)) {
> > > > int ret;
> > > >
> > > > - /* TODO currently we don't support multiple node types
> > > > - * we need to run skb_clone at rx path. Check if there
> > > > - * exist really an use case if we need to support
> > > > - * multiple node types at the same time.
> > > > + /* TODO currently we don't support multiple node/coord
> > > > + * types we need to run skb_clone at rx path. Check if
> > > > + * there exist really an use case if we need to support
> > > > + * multiple node/coord types at the same time.
> > > > */
> > > > - if (wpan_dev->iftype == NL802154_IFTYPE_NODE &&
> > > > - nsdata->wpan_dev.iftype == NL802154_IFTYPE_NODE)
> > > > + if (wpan_dev->iftype != NL802154_IFTYPE_MONITOR &&
> > > > + nsdata->wpan_dev.iftype != NL802154_IFTYPE_MONITOR)
> > > > return -EBUSY;
> > > >
> > > > /* check all phy mac sublayer settings are the same.
> > > > @@ -577,6 +577,7 @@ ieee802154_setup_sdata(struct ieee802154_sub_if_data *sdata,
> > > > wpan_dev->short_addr = cpu_to_le16(IEEE802154_ADDR_BROADCAST);
> > > >
> > > > switch (type) {
> > > > + case NL802154_IFTYPE_COORD:
> > > > case NL802154_IFTYPE_NODE:
> > > > ieee802154_be64_to_le64(&wpan_dev->extended_addr,
> > > > sdata->dev->dev_addr);
> > > > @@ -636,6 +637,7 @@ ieee802154_if_add(struct ieee802154_local *local, const char *name,
> > > > ieee802154_le64_to_be64(ndev->perm_addr,
> > > > &local->hw.phy->perm_extended_addr);
> > > > switch (type) {
> > > > + case NL802154_IFTYPE_COORD:
> > > > case NL802154_IFTYPE_NODE:
> > > > ndev->type = ARPHRD_IEEE802154;
> > > > if (ieee802154_is_valid_extended_unicast_addr(extended_addr)) {
> > > > diff --git a/net/mac802154/rx.c b/net/mac802154/rx.c
> > > > index b8ce84618a55..39459d8d787a 100644
> > > > --- a/net/mac802154/rx.c
> > > > +++ b/net/mac802154/rx.c
> > > > @@ -203,7 +203,7 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
> > > > }
> > > >
> > > > list_for_each_entry_rcu(sdata, &local->interfaces, list) {
> > > > - if (sdata->wpan_dev.iftype != NL802154_IFTYPE_NODE)
> > > > + if (sdata->wpan_dev.iftype == NL802154_IFTYPE_MONITOR)
> > > > continue;
> > >
> > > I probably get why you are doing that, but first the overall design is
> > > working differently - means you should add an additional receive path
> > > for the special interface type.
> > >
> > > Also we "discovered" before that the receive path of node vs
> > > coordinator is different... Where is the different handling here? I
> > > don't see it, I see that NODE and COORD are the same now (because that
> > > is _currently_ everything else than monitor). This change is not
> > > enough and does "something" to handle in some way coordinator receive
> > > path but there are things missing.
> > >
> > > 1. Changing the address filters that it signals the transceiver it's
> > > acting as coordinator
> > > 2. We _should_ also have additional handling for whatever the
> > > additional handling what address filters are doing in mac802154
> > > _because_ there is hardware which doesn't have address filtering e.g.
> > > hwsim which depend that this is working in software like other
> > > transceiver hardware address filters.
> > >
> > > For the 2. one, I don't know if we do that even for NODE right or we
> > > just have the bare minimal support there... I don't assume that
> > > everything is working correctly here but what I want to see is a
> > > separate receive path for coordinators that people can send patches to
> > > fix it.
> >
> > Yes, we do very little differently between the two modes, that's why I
> > took the easy way: just changing the condition. I really don't see what
> > I can currently add here, but I am fine changing the style to easily
> > show people where to add filters for such or such interface, but right
> > now both path will look very "identical", do we agree on that?
>
> mostly yes, but there exists a difference and we should at least check
> if the node receive path violates the coordinator receive path and
> vice versa.
> Put it in a receive_path() function and then coord_receive_path(),
> node_receive_path() that calls the receive_path() and do the
> additional filtering for coordinators, etc.
>
> There should be a part in the standard about "third level filter rule
> if it's a coordinator".
> btw: this is because the address filter on the transceiver needs to
> have the "i am a coordinator" boolean set which is missing in this
> series. However it depends on the transceiver filtering level and the
> mac802154 receive path if we actually need to run such filtering or
> not.
I must be missing some information because I can't find any places
where what you suggest is described in the spec.
I agree there are multiple filtering level so let's go through them one
by one (6.7.2 Reception and rejection):
- first level: is the checksum (FCS) valid?
yes -> goto second level
no -> drop
- second level: are we in promiscuous mode?
yes -> forward to upper layers
no -> goto second level (bis)
- second level (bis): are we scanning?
yes -> goto scan filtering
no -> goto third level
- scan filtering: is it a beacon?
yes -> process the beacon
no -> drop
- third level: is the frame valid? (type, source, destination, pan id,
etc)
yes -> forward to upper layers
no -> drop
But none of them, as you said, is dependent on the interface type.
There is no mention of a specific filtering operation to do in all
those cases when running in COORD mode. So I still don't get what
should be included in either node_receive_path() which should be
different than in coord_receive_path() for now.
There are, however, two situations where the interface type has its
importance:
- Enhanced beacon requests with Enhanced beacon filter IE, which asks
the receiving device to process/drop the request upon certain
conditions (minimum LQI and/or randomness), as detailed in
7.4.4.6 Enhanced Beacon Filter IE. But, as mentioned in
7.5.9 Enhanced Beacon Request command: "The Enhanced Beacon Request
command is optional for an FFD and an RFD", so this series was only
targeting basic beaconing for now.
- In relaying mode, the destination address must not be validated
because the message needs to be re-emitted. Indeed, a receiver in
relaying mode may not be the recipient. This is also optional and out
of the scope of this series.
Right now I have the below diff, which clarifies the two path, without
too much changes in the current code because I don't really see why it
would be necessary. Unless you convince me otherwise or read the spec
differently than I do :) What do you think?
Thanks,
Miquèl
---
--- a/net/mac802154/rx.c
+++ b/net/mac802154/rx.c
@@ -194,6 +194,7 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
int ret;
struct ieee802154_sub_if_data *sdata;
struct ieee802154_hdr hdr;
+ bool iface_found = false;
ret = ieee802154_parse_frame_start(skb, &hdr);
if (ret) {
@@ -203,18 +204,31 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
}
list_for_each_entry_rcu(sdata, &local->interfaces, list) {
- if (sdata->wpan_dev.iftype != NL802154_IFTYPE_NODE)
+ if (sdata->wpan_dev.iftype == NL802154_IFTYPE_MONITOR)
continue;
if (!ieee802154_sdata_running(sdata))
continue;
+ iface_found = true;
+ break;
+ }
+
+ if (!iface_found) {
+ kfree_skb(skb);
+ return;
+ }
+
+ /* TBD: Additional filtering is possible on NODEs and/or COORDINATORs */
+ switch (sdata->wpan_dev.iftype) {
+ case NL802154_IFTYPE_COORD:
+ case NL802154_IFTYPE_NODE:
ieee802154_subif_frame(sdata, skb, &hdr);
- skb = NULL;
+ break;
+ default:
+ kfree_skb(skb);
break;
}
-
- kfree_skb(skb);
}
static void
