[net-next 12/18] net: mac802154: Handle scan requests

From: Miquel Raynal
Date: Wed Dec 22 2021 - 10:58:23 EST

Implement the core hooks in order to provide the softMAC layer support
for scan requests and aborts.

Changing the channels is prohibited during the scan.

The implementation uses a workqueue triggered at a certain interval
depending on the symbol duration for the current channel and the
duration order provided.

Received beacons during a passive scanning procedure are processed and
either registered in the list of known PANs or the existing entry gets
updated accordingly.

Active scanning is not supported yet.

Co-developed-by: David Girault <david.girault@xxxxxxxxx>
Signed-off-by: David Girault <david.girault@xxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
include/linux/ieee802154.h | 4 +
include/net/mac802154.h | 14 ++
net/mac802154/Makefile | 2 +-
net/mac802154/cfg.c | 39 ++++++
net/mac802154/ieee802154_i.h | 15 +++
net/mac802154/main.c | 2 +
net/mac802154/rx.c | 10 +-
net/mac802154/scan.c | 248 +++++++++++++++++++++++++++++++++++
net/mac802154/util.c | 26 ++++
9 files changed, 357 insertions(+), 3 deletions(-)
create mode 100644 net/mac802154/scan.c

diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
index a9b09a9b8f70..60b09ff65d3d 100644
--- a/include/linux/ieee802154.h
+++ b/include/linux/ieee802154.h
@@ -46,6 +46,10 @@

/* Duration in superframe order */
#define IEEE802154_MAX_SCAN_DURATION 14
+/* Superframe duration in slots */
+#define IEEE802154_SUPERFRAME_PERIOD 16
+/* Various periods expressed in symbols */
+#define IEEE802154_SLOT_PERIOD 60
#define IEEE802154_LIFS_PERIOD 40
#define IEEE802154_SIFS_PERIOD 12
#define IEEE802154_MAX_SIFS_FRAME_SIZE 18
diff --git a/include/net/mac802154.h b/include/net/mac802154.h
index d524ffb9eb25..19bfbf591ea1 100644
--- a/include/net/mac802154.h
+++ b/include/net/mac802154.h
@@ -486,4 +486,18 @@ void ieee802154_stop_queue(struct ieee802154_hw *hw);
void ieee802154_xmit_complete(struct ieee802154_hw *hw, struct sk_buff *skb,
bool ifs_handling);

+/**
+ * ieee802154_queue_delayed_work - add work onto the mac802154 workqueue
+ *
+ * Drivers and mac802154 use this to queue delayed work onto the mac802154
+ * workqueue.
+ *
+ * @hw: the hardware struct for the interface we are adding work for
+ * @dwork: delayable work to queue onto the mac802154 workqueue
+ * @delay: number of jiffies to wait before queueing
+ */
+void ieee802154_queue_delayed_work(struct ieee802154_hw *hw,
+ struct delayed_work *dwork,
+ unsigned long delay);
+
#endif /* NET_MAC802154_H */
diff --git a/net/mac802154/Makefile b/net/mac802154/Makefile
index 4059295fdbf8..43d1347b37ee 100644
--- a/net/mac802154/Makefile
+++ b/net/mac802154/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_MAC802154) += mac802154.o
mac802154-objs := main.o rx.o tx.o mac_cmd.o mib.o \
- iface.o llsec.o util.o cfg.o trace.o
+ iface.o llsec.o util.o cfg.o scan.o trace.o

CFLAGS_trace.o := -I$(src)
diff --git a/net/mac802154/cfg.c b/net/mac802154/cfg.c
index fbeebe3bc31d..5c19d6f8e3eb 100644
--- a/net/mac802154/cfg.c
+++ b/net/mac802154/cfg.c
@@ -114,6 +114,10 @@ ieee802154_set_channel(struct wpan_phy *wpan_phy, u8 page, u8 channel)
wpan_phy->current_channel == channel)
return 0;

+ /* Refuse to change channels during a scanning operation */
+ if (local->scanning)
+ return -EBUSY;
+
ret = drv_set_channel(local, page, channel);
if (!ret) {
wpan_phy->current_page = page;
@@ -260,6 +264,39 @@ ieee802154_set_ackreq_default(struct wpan_phy *wpan_phy,
return 0;
}

+static int mac802154_trigger_scan(struct wpan_phy *wpan_phy,
+ struct cfg802154_scan_request *req)
+{
+ struct ieee802154_local *local = wpan_phy_priv(wpan_phy);
+ struct ieee802154_sub_if_data *sdata;
+ int ret;
+
+ sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(req->wpan_dev);
+
+ ASSERT_RTNL();
+
+ mutex_lock(&local->scan_lock);
+ ret = mac802154_trigger_scan_locked(sdata, req);
+ mutex_unlock(&local->scan_lock);
+
+ return ret;
+}
+
+static int mac802154_abort_scan(struct wpan_phy *wpan_phy,
+ struct wpan_dev *wpan_dev)
+{
+ struct ieee802154_local *local = wpan_phy_priv(wpan_phy);
+ int ret;
+
+ ASSERT_RTNL();
+
+ mutex_lock(&local->scan_lock);
+ ret = mac802154_abort_scan_locked(local);
+ mutex_unlock(&local->scan_lock);
+
+ return ret;
+}
+
#ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
static void
ieee802154_get_llsec_table(struct wpan_phy *wpan_phy,
@@ -467,6 +504,8 @@ const struct cfg802154_ops mac802154_config_ops = {
.set_max_frame_retries = ieee802154_set_max_frame_retries,
.set_lbt_mode = ieee802154_set_lbt_mode,
.set_ackreq_default = ieee802154_set_ackreq_default,
+ .trigger_scan = mac802154_trigger_scan,
+ .abort_scan = mac802154_abort_scan,
#ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
.get_llsec_table = ieee802154_get_llsec_table,
.lock_llsec_table = ieee802154_lock_llsec_table,
diff --git a/net/mac802154/ieee802154_i.h b/net/mac802154/ieee802154_i.h
index 702560acc8ce..4945edf5c2ce 100644
--- a/net/mac802154/ieee802154_i.h
+++ b/net/mac802154/ieee802154_i.h
@@ -48,6 +48,15 @@ struct ieee802154_local {

struct hrtimer ifs_timer;

+ /* Scanning */
+ struct mutex scan_lock;
+ unsigned long scanning;
+ __le64 scan_addr;
+ int scan_channel_idx;
+ struct cfg802154_scan_request __rcu *scan_req;
+ struct ieee802154_sub_if_data __rcu *scan_sdata;
+ struct delayed_work scan_work;
+
bool started;
bool suspended;

@@ -166,6 +175,12 @@ void mac802154_unlock_table(struct net_device *dev);

int mac802154_wpan_update_llsec(struct net_device *dev);

+/* scanning handling */
+void mac802154_scan_work(struct work_struct *work);
+int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
+ struct cfg802154_scan_request *request);
+int mac802154_abort_scan_locked(struct ieee802154_local *local);
+int mac802154_scan_rx(struct ieee802154_local *local, struct sk_buff *skb);
/* interface handling */
int ieee802154_iface_init(void);
void ieee802154_iface_exit(void);
diff --git a/net/mac802154/main.c b/net/mac802154/main.c
index 520cedc594e1..568991734610 100644
--- a/net/mac802154/main.c
+++ b/net/mac802154/main.c
@@ -90,12 +90,14 @@ ieee802154_alloc_hw(size_t priv_data_len, const struct ieee802154_ops *ops)

INIT_LIST_HEAD(&local->interfaces);
mutex_init(&local->iflist_mtx);
+ mutex_init(&local->scan_lock);

tasklet_setup(&local->tasklet, ieee802154_tasklet_handler);

skb_queue_head_init(&local->skb_queue);

INIT_WORK(&local->tx_work, ieee802154_xmit_worker);
+ INIT_DELAYED_WORK(&local->scan_work, mac802154_scan_work);

/* init supported flags with 802.15.4 default ranges */
phy->supported.max_minbe = 8;
diff --git a/net/mac802154/rx.c b/net/mac802154/rx.c
index b8ce84618a55..acbce67caedc 100644
--- a/net/mac802154/rx.c
+++ b/net/mac802154/rx.c
@@ -198,8 +198,13 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
ret = ieee802154_parse_frame_start(skb, &hdr);
if (ret) {
pr_debug("got invalid frame\n");
- kfree_skb(skb);
- return;
+ goto free_skb;
+ }
+
+ if (unlikely(local->scanning)) {
+ if (mac_cb(skb)->type == IEEE802154_FC_TYPE_BEACON)
+ mac802154_scan_rx(local, skb);
+ goto free_skb;
}

list_for_each_entry_rcu(sdata, &local->interfaces, list) {
@@ -214,6 +219,7 @@ __ieee802154_rx_handle_packet(struct ieee802154_local *local,
break;
}

+free_skb:
kfree_skb(skb);
}

diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c
new file mode 100644
index 000000000000..c5b85eaec319
--- /dev/null
+++ b/net/mac802154/scan.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * IEEE 802.15.4 scanning management
+ *
+ * Copyright (C) Qorvo, 2021
+ * Authors:
+ * - David Girault <david.girault@xxxxxxxxx>
+ * - Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
+ */
+
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/rtnetlink.h>
+#include <net/mac802154.h>
+
+#include "ieee802154_i.h"
+#include "driver-ops.h"
+#include "../ieee802154/nl802154.h"
+
+static bool mac802154_check_promiscuous(struct ieee802154_local *local)
+{
+ struct ieee802154_sub_if_data *sdata;
+ bool promiscuous_on = false;
+
+ /* Check if one subif is already in promiscuous mode. Since the list is
+ * protected by its own mutex, take it here to ensure no modification
+ * occurs during the check.
+ */
+ mutex_lock(&local->iflist_mtx);
+ list_for_each_entry(sdata, &local->interfaces, list) {
+ if (ieee802154_sdata_running(sdata) &&
+ sdata->wpan_dev.promiscuous_mode) {
+ /* At least one is in promiscuous mode */
+ promiscuous_on = true;
+ break;
+ }
+ }
+ mutex_unlock(&local->iflist_mtx);
+ return promiscuous_on;
+}
+
+static int mac802154_set_promiscuous_mode(struct ieee802154_local *local,
+ bool state)
+{
+ bool promiscuous_on = mac802154_check_promiscuous(local);
+ int ret;
+
+ if ((state && promiscuous_on) || (!state && !promiscuous_on))
+ return 0;
+
+ ret = drv_set_promiscuous_mode(local, state);
+ if (ret)
+ pr_err("Failed to %s promiscuous mode for SW scanning",
+ state ? "set" : "reset");
+
+ return ret;
+}
+
+static int mac802154_send_scan_done(struct ieee802154_local *local)
+{
+ struct cfg802154_registered_device *rdev;
+ struct cfg802154_scan_request *scan_req;
+ struct wpan_dev *wpan_dev;
+
+ scan_req = rcu_dereference_protected(local->scan_req,
+ lockdep_is_held(&local->scan_lock));
+ rdev = wpan_phy_to_rdev(scan_req->wpan_phy);
+ wpan_dev = scan_req->wpan_dev;
+
+ return nl802154_send_scan_done(rdev, wpan_dev);
+}
+
+static int mac802154_end_of_scan(struct ieee802154_local *local)
+{
+ drv_set_channel(local, local->phy->current_page,
+ local->phy->current_channel);
+ local->scanning = false;
+ mac802154_set_promiscuous_mode(local, false);
+
+ return mac802154_send_scan_done(local);
+}
+
+int mac802154_abort_scan_locked(struct ieee802154_local *local)
+{
+ lockdep_assert_held(&local->scan_lock);
+
+ if (!local->scanning)
+ return -ESRCH;
+
+ cancel_delayed_work(&local->scan_work);
+
+ return mac802154_end_of_scan(local);
+}
+
+static unsigned int mac802154_scan_get_channel_time(u8 duration_order,
+ u8 symbol_duration)
+{
+ u64 base_super_frame_duration = (u64)symbol_duration *
+ IEEE802154_SUPERFRAME_PERIOD * IEEE802154_SLOT_PERIOD;
+
+ return usecs_to_jiffies(base_super_frame_duration *
+ (BIT(duration_order) + 1));
+}
+
+void mac802154_scan_work(struct work_struct *work)
+{
+ struct ieee802154_local *local =
+ container_of(work, struct ieee802154_local, scan_work.work);
+ struct cfg802154_scan_request *scan_req;
+ struct ieee802154_sub_if_data *sdata;
+ unsigned int scan_duration;
+ bool end_of_scan = false;
+ unsigned long chan;
+ int ret;
+
+ mutex_lock(&local->scan_lock);
+
+ if (!local->scanning)
+ goto unlock_mutex;
+
+ sdata = rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->scan_lock));
+ scan_req = rcu_dereference_protected(local->scan_req,
+ lockdep_is_held(&local->scan_lock));
+
+ if (local->suspended || !ieee802154_sdata_running(sdata))
+ goto queue_work;
+
+ do {
+ chan = find_next_bit((const unsigned long *)&scan_req->channels,
+ IEEE802154_MAX_CHANNEL + 1,
+ local->scan_channel_idx + 1);
+
+ /* If there are no more channels left, complete the scan */
+ if (chan > IEEE802154_MAX_CHANNEL) {
+ end_of_scan = true;
+ goto unlock_mutex;
+ }
+
+ /* Channel switch cannot be made atomic so hide the chan number
+ * in order to prevent beacon processing during this timeframe.
+ */
+ local->scan_channel_idx = -1;
+ /* Bypass the stack on purpose */
+ ret = drv_set_channel(local, scan_req->page, chan);
+ local->scan_channel_idx = chan;
+ } while (ret);
+
+queue_work:
+ scan_duration = mac802154_scan_get_channel_time(scan_req->duration,
+ local->phy->symbol_duration);
+ pr_debug("Scan channel %lu of page %u for %ums\n",
+ chan, scan_req->page, jiffies_to_msecs(scan_duration));
+ ieee802154_queue_delayed_work(&local->hw, &local->scan_work,
+ scan_duration);
+
+unlock_mutex:
+ if (end_of_scan)
+ mac802154_end_of_scan(local);
+
+ mutex_unlock(&local->scan_lock);
+}
+
+int mac802154_trigger_scan_locked(struct ieee802154_sub_if_data *sdata,
+ struct cfg802154_scan_request *request)
+{
+ struct ieee802154_local *local = sdata->local;
+ int ret;
+
+ lockdep_assert_held(&local->scan_lock);
+
+ if (local->scanning)
+ return -EBUSY;
+
+ /* TODO: support other scanning type */
+ if (request->type != NL802154_SCAN_PASSIVE)
+ return -EOPNOTSUPP;
+
+ /* Store scanning parameters */
+ rcu_assign_pointer(local->scan_req, request);
+ rcu_assign_pointer(local->scan_sdata, sdata);
+
+ /* Configure scan_addr to use net_device addr or random */
+ if (request->flags & NL802154_SCAN_FLAG_RANDOM_ADDR)
+ get_random_bytes(&local->scan_addr, sizeof(local->scan_addr));
+ else
+ local->scan_addr = cpu_to_le64(get_unaligned_be64(sdata->dev->dev_addr));
+
+ local->scan_channel_idx = -1;
+ local->scanning = true;
+
+ /* Software scanning requires to set promiscuous mode */
+ ret = mac802154_set_promiscuous_mode(local, true);
+ if (ret)
+ return mac802154_end_of_scan(local);
+
+ ieee802154_queue_delayed_work(&local->hw, &local->scan_work, 0);
+
+ return 0;
+}
+
+int mac802154_scan_rx(struct ieee802154_local *local, struct sk_buff *skb)
+{
+ struct ieee802154_beaconhdr *bh = (void *)skb->data;
+ struct ieee802154_addr *src = &mac_cb(skb)->source;
+ struct cfg802154_scan_request *scan_req;
+ struct ieee802154_pan_desc desc = {};
+ int ret;
+
+ /* Check the validity of the frame length */
+ if (skb->len < sizeof(*bh))
+ return -EINVAL;
+
+ if (unlikely(src->mode == IEEE802154_ADDR_NONE))
+ return -EINVAL;
+
+ if (unlikely(!bh->pan_coordinator))
+ return -ENODEV;
+
+ scan_req = rcu_dereference(local->scan_req);
+ if (unlikely(!scan_req))
+ return -EINVAL;
+
+ if (unlikely(local->scan_channel_idx < 0)) {
+ pr_info("Dropping beacon received during channel change\n");
+ return 0;
+ }
+
+ pr_debug("Beacon received on channel %d of page %d\n",
+ local->scan_channel_idx, scan_req->page);
+
+ /* Parse beacon and create PAN information */
+ desc.coord = src;
+ desc.page = scan_req->page;
+ desc.channel = local->scan_channel_idx;
+ desc.link_quality = mac_cb(skb)->lqi;
+ desc.superframe_spec = get_unaligned_le16(skb->data);
+ desc.gts_permit = bh->gts_permit;
+
+ /* Create or update the PAN entry in the management layer */
+ ret = cfg802154_record_pan(local->phy, &desc);
+ if (ret) {
+ pr_err("Failed to save PAN descriptor\n");
+ return ret;
+ }
+
+ return 0;
+}
diff --git a/net/mac802154/util.c b/net/mac802154/util.c
index f2078238718b..5ee65cb1dbcd 100644
--- a/net/mac802154/util.c
+++ b/net/mac802154/util.c
@@ -94,3 +94,29 @@ void ieee802154_stop_device(struct ieee802154_local *local)
hrtimer_cancel(&local->ifs_timer);
drv_stop(local);
}
+
+/* Nothing should have been stuffed into the workqueue during
+ * the suspend->resume cycle.
+ */
+static bool ieee802154_can_queue_work(struct ieee802154_local *local)
+{
+ if (local->suspended) {
+ pr_warn("queueing ieee802154 work while suspended\n");
+ return false;
+ }
+
+ return true;
+}
+
+void ieee802154_queue_delayed_work(struct ieee802154_hw *hw,
+ struct delayed_work *dwork,
+ unsigned long delay)
+{
+ struct ieee802154_local *local = hw_to_local(hw);
+
+ if (!ieee802154_can_queue_work(local))
+ return;
+
+ queue_delayed_work(local->workqueue, dwork, delay);
+}
+EXPORT_SYMBOL(ieee802154_queue_delayed_work);
--
2.27.0