Hi,
On Fri, Jul 1, 2022 at 10:36 AM Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
>
> Implement the core hooks in order to provide the softMAC layer support
> for passive scans. Scans are requested by the user and can be aborted.
>
> Changing the channels is prohibited during the scan.
>
> As transceivers enter promiscuous mode during scans, they might stop
> checking frame validity so we ensure this gets done at mac level.
>
> 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 scan are processed also in a work
> queue and forwarded to the upper layer.
>
> 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/cfg802154.h | 12 ++
> net/mac802154/Makefile | 2 +-
> net/mac802154/cfg.c | 39 ++++++
> net/mac802154/ieee802154_i.h | 29 ++++
> net/mac802154/iface.c | 6 +
> net/mac802154/main.c | 4 +
> net/mac802154/rx.c | 49 ++++++-
> net/mac802154/scan.c | 264 +++++++++++++++++++++++++++++++++++
> 9 files changed, 405 insertions(+), 4 deletions(-)
> create mode 100644 net/mac802154/scan.c
>
> diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h
> index 929d4e672575..94bfee22bd0a 100644
> --- a/include/linux/ieee802154.h
> +++ b/include/linux/ieee802154.h
> @@ -47,6 +47,10 @@
> /* Duration in superframe order */
> #define IEEE802154_MAX_SCAN_DURATION 14
> #define IEEE802154_ACTIVE_SCAN_DURATION 15
> +/* 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/cfg802154.h b/include/net/cfg802154.h
> index f05ce3c45b5d..206283fd4b72 100644
> --- a/include/net/cfg802154.h
> +++ b/include/net/cfg802154.h
> @@ -300,6 +300,18 @@ struct cfg802154_scan_request {
> struct wpan_phy *wpan_phy;
> };
>
> +/**
> + * struct cfg802154_mac_pkt - MAC packet descriptor (beacon/command)
> + * @node: MAC packets to process list member
> + * @skb: the received sk_buff
> + * @sdata: the interface on which @skb was received
> + */
> +struct cfg802154_mac_pkt {
> + struct list_head node;
> + struct sk_buff *skb;
> + struct ieee802154_sub_if_data *sdata;
> +};
> +
> struct ieee802154_llsec_key_id {
> u8 mode;
> u8 id;
> 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 4116a894c86e..1f532d93d870 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 (mac802154_is_scanning(local))
> + return -EBUSY;
> +
okay, that answered one of my other questions in another mail.
> ret = drv_set_channel(local, page, channel);
> if (!ret) {
> wpan_phy->current_page = page;
> @@ -261,6 +265,39 @@ 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 *request)
> +{
> + struct ieee802154_local *local = wpan_phy_priv(wpan_phy);
> + struct ieee802154_sub_if_data *sdata;
> + int ret;
> +
> + sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(request->wpan_dev);
> +
> + ASSERT_RTNL();
> +
> + mutex_lock(&local->scan_lock);
> + ret = mac802154_trigger_scan_locked(sdata, request);
> + 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,
> @@ -468,6 +505,8 @@ 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 b8775bcc9003..46394e2e0486 100644
> --- a/net/mac802154/ieee802154_i.h
> +++ b/net/mac802154/ieee802154_i.h
> @@ -21,6 +21,10 @@
>
> #include "llsec.h"
>
> +enum ieee802154_ongoing {
> + IEEE802154_IS_SCANNING = BIT(0),
> +};
> +
> /* mac802154 device private data */
> struct ieee802154_local {
> struct ieee802154_hw hw;
> @@ -50,8 +54,19 @@ struct ieee802154_local {
>
> struct hrtimer ifs_timer;
>
> + /* Scanning */
> + struct mutex scan_lock;
> + int scan_channel_idx;
> + struct cfg802154_scan_request __rcu *scan_req;
> + struct delayed_work scan_work;
> +
> + /* Asynchronous tasks */
> + struct list_head rx_beacon_list;
> + struct work_struct rx_beacon_work;
> +
> bool started;
> bool suspended;
> + unsigned long ongoing;
>
> struct tasklet_struct tasklet;
> struct sk_buff_head skb_queue;
> @@ -210,6 +225,20 @@ void mac802154_unlock_table(struct net_device *dev);
>
> int mac802154_wpan_update_llsec(struct net_device *dev);
>
> +/* PAN management handling */
> +void mac802154_scan_worker(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_process_beacon(struct ieee802154_local *local,
> + struct sk_buff *skb);
> +void mac802154_rx_beacon_worker(struct work_struct *work);
> +
> +static inline bool mac802154_is_scanning(struct ieee802154_local *local)
> +{
> + return test_bit(IEEE802154_IS_SCANNING, &local->ongoing);
> +}
> +
> /* interface handling */
> int ieee802154_iface_init(void);
> void ieee802154_iface_exit(void);
> diff --git a/net/mac802154/iface.c b/net/mac802154/iface.c
> index 7715e17d9ba1..431cc544dbf2 100644
> --- a/net/mac802154/iface.c
> +++ b/net/mac802154/iface.c
> @@ -315,6 +315,12 @@ static int mac802154_slave_close(struct net_device *dev)
>
> ASSERT_RTNL();
>
> + if (mac802154_is_scanning(local)) {
> + mutex_lock(&local->scan_lock);
> + mac802154_abort_scan_locked(local);
> + mutex_unlock(&local->scan_lock);
> + }
> +
> mutex_lock(&local->device_lock);
>
> netif_stop_queue(dev);
> diff --git a/net/mac802154/main.c b/net/mac802154/main.c
> index e5fb7ed73663..604fbc5b07df 100644
> --- a/net/mac802154/main.c
> +++ b/net/mac802154/main.c
> @@ -89,14 +89,18 @@ ieee802154_alloc_hw(size_t priv_data_len, const struct ieee802154_ops *ops)
> local->ops = ops;
>
> INIT_LIST_HEAD(&local->interfaces);
> + INIT_LIST_HEAD(&local->rx_beacon_list);
> mutex_init(&local->iflist_mtx);
> mutex_init(&local->device_lock);
> + mutex_init(&local->scan_lock);
>
> tasklet_setup(&local->tasklet, ieee802154_tasklet_handler);
>
> skb_queue_head_init(&local->skb_queue);
>
> INIT_WORK(&local->sync_tx_work, ieee802154_xmit_sync_worker);
> + INIT_DELAYED_WORK(&local->scan_work, mac802154_scan_worker);
> + INIT_WORK(&local->rx_beacon_work, mac802154_rx_beacon_worker);
>
> /* 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 39459d8d787a..0b1cf8c85ee9 100644
> --- a/net/mac802154/rx.c
> +++ b/net/mac802154/rx.c
> @@ -29,11 +29,36 @@ static int ieee802154_deliver_skb(struct sk_buff *skb)
> return netif_receive_skb(skb);
> }
>
> +void mac802154_rx_beacon_worker(struct work_struct *work)
> +{
> + struct ieee802154_local *local =
> + container_of(work, struct ieee802154_local, rx_beacon_work);
> + struct cfg802154_mac_pkt *mac_pkt;
> +
> + mutex_lock(&local->scan_lock);
> +
> + if (list_empty(&local->rx_beacon_list))
> + goto unlock;
> +
> + mac_pkt = list_first_entry(&local->rx_beacon_list,
> + struct cfg802154_mac_pkt, node);
> +
> + mac802154_process_beacon(local, mac_pkt->skb);
> +
> + list_del(&mac_pkt->node);
> + kfree_skb(mac_pkt->skb);
> + kfree(mac_pkt);
> +
> +unlock:
> + mutex_unlock(&local->scan_lock);
> +}
> +
> static int
> ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
> struct sk_buff *skb, const struct ieee802154_hdr *hdr)
> {
> struct wpan_dev *wpan_dev = &sdata->wpan_dev;
> + struct cfg802154_mac_pkt *mac_pkt;
> __le16 span, sshort;
> int rc;
>
> @@ -94,6 +119,18 @@ ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
>
> switch (mac_cb(skb)->type) {
> case IEEE802154_FC_TYPE_BEACON:
> + if (!mac802154_is_scanning(sdata->local))
> + goto fail;
> +
> + mac_pkt = kzalloc(sizeof(*mac_pkt), GFP_ATOMIC);
> + if (!mac_pkt)
> + goto fail;
> +
> + mac_pkt->skb = skb_get(skb);
> + mac_pkt->sdata = sdata;
> + list_add_tail(&mac_pkt->node, &sdata->local->rx_beacon_list);
> + queue_work(sdata->local->workqueue, &sdata->local->rx_beacon_work);
> + goto success;
> case IEEE802154_FC_TYPE_ACK:
> case IEEE802154_FC_TYPE_MAC_CMD:
> goto fail;
> @@ -109,6 +146,10 @@ ieee802154_subif_frame(struct ieee802154_sub_if_data *sdata,
> fail:
> kfree_skb(skb);
> return NET_RX_DROP;
> +
> +success:
> + kfree_skb(skb);
> + return NET_RX_SUCCESS;
> }
>
> static void
> @@ -268,10 +309,12 @@ void ieee802154_rx(struct ieee802154_local *local, struct sk_buff *skb)
>
> ieee802154_monitors_rx(local, skb);
>
> - /* Check if transceiver doesn't validate the checksum.
> - * If not we validate the checksum here.
> + /* Check if the transceiver doesn't validate the checksum, or if the
> + * check might have been disabled like during a scan. In these cases,
> + * we validate the checksum here.
> */
> - if (local->hw.flags & IEEE802154_HW_RX_DROP_BAD_CKSUM) {
> + if (local->hw.flags & IEEE802154_HW_RX_DROP_BAD_CKSUM ||
> + mac802154_is_scanning(local)) {
> crc = crc_ccitt(0, skb->data, skb->len);
> if (crc) {
> rcu_read_unlock();
> diff --git a/net/mac802154/scan.c b/net/mac802154/scan.c
> new file mode 100644
> index 000000000000..c74f6c3baa95
> --- /dev/null
> +++ b/net/mac802154/scan.c
> @@ -0,0 +1,264 @@
> +// 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/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.
> + */
> + rcu_read_lock();
> + 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;
> + }
> + }
> + rcu_read_unlock();
> +
> + 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_scan_request *scan_req;
> + struct wpan_phy *wpan_phy;
> + struct wpan_dev *wpan_dev;
> +
> + scan_req = rcu_dereference_protected(local->scan_req,
> + lockdep_is_held(&local->scan_lock));
> + wpan_phy = scan_req->wpan_phy;
> + wpan_dev = scan_req->wpan_dev;
> +
> + cfg802154_flush_known_coordinators(wpan_dev);
> +
> + return nl802154_send_scan_done(wpan_phy, wpan_dev, scan_req);
> +}
> +
> +static int mac802154_end_of_scan(struct ieee802154_local *local)
> +{
> + drv_set_channel(local, local->phy->current_page,
> + local->phy->current_channel);
> + ieee802154_configure_durations(local->phy, local->phy->current_page,
> + local->phy->current_channel);
> + clear_bit(IEEE802154_IS_SCANNING, &local->ongoing);
> + mac802154_set_promiscuous_mode(local, false);
> + ieee802154_mlme_op_post(local);
> + module_put(local->hw.parent->driver->owner);
> +
> + return mac802154_send_scan_done(local);
> +}
> +
> +int mac802154_abort_scan_locked(struct ieee802154_local *local)
> +{
> + lockdep_assert_held(&local->scan_lock);
> +
> + if (!mac802154_is_scanning(local))
> + 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_flush_queued_beacons(struct ieee802154_local *local)
> +{
> + struct cfg802154_mac_pkt *beacon, *tmp;
> +
> + lockdep_assert_held(&local->scan_lock);
> +
> + list_for_each_entry_safe(beacon, tmp, &local->rx_beacon_list, node) {
> + list_del(&beacon->node);
> + kfree_skb(beacon->skb);
> + kfree(beacon);
> + }
> +}
> +
> +void mac802154_scan_worker(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;
> + unsigned long chan;
> + int ret;
> +
> + mutex_lock(&local->scan_lock);
> +
> + if (!mac802154_is_scanning(local))
> + goto unlock_mutex;
> +
> + scan_req = rcu_dereference_protected(local->scan_req,
> + lockdep_is_held(&local->scan_lock));
> + sdata = IEEE802154_WPAN_DEV_TO_SUB_IF(scan_req->wpan_dev);
> +
> + 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) {
> + mac802154_end_of_scan(local);
> + goto unlock_mutex;
> + }
> +
> + /* Bypass the stack on purpose. As the channel change cannot be
> + * made atomic with regard to the incoming beacon flow, we flush
> + * the beacons list after changing the channel and before
> + * releasing the scan lock, to avoid processing beacons which
> + * have been received during this time frame.
> + */
> + ret = drv_set_channel(local, scan_req->page, chan);
> + local->scan_channel_idx = chan;
> + ieee802154_configure_durations(local->phy, scan_req->page, chan);
> + mac802154_flush_queued_beacons(local);
> + } 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));
> + queue_delayed_work(local->workqueue, &local->scan_work, scan_duration);
> +
> +unlock_mutex:
> + 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 (mac802154_is_scanning(local))
> + 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);
> +
> + /* Software scanning requires to set promiscuous mode, so we need to
> + * pause the Tx queue during the entire operation.
> + */
> + ieee802154_mlme_op_pre(local);
> +
> + ret = mac802154_set_promiscuous_mode(local, true);
> + if (ret)
> + goto cancel_mlme;
I know some driver datasheets and as I said before, it's not allowed
to set promiscuous mode while in receive mode. We need to stop tx,
what we are doing. Then call stop() driver callback,
synchronize_net(), mac802154_set_promiscuous_mode(...), start(). The
same always for the opposite.
- Alex
