// SPDX-License-Identifier: GPL-2.0 /* drivers/net/wireless/virt_wifi.c * * A fake implementation of cfg80211_ops that can be tacked on to an ethernet * net_device to make it appear as a wireless connection. * * Copyright (C) 2018 Google, Inc. * * Author: schuffelen@google.com */ #include #include #include #include #include #include #include #include static struct wiphy *common_wiphy; struct virt_wifi_wiphy_priv { struct delayed_work scan_result; struct cfg80211_scan_request *scan_request; bool being_deleted; }; static struct ieee80211_channel channel_2ghz = { .band = NL80211_BAND_2GHZ, .center_freq = 2432, .hw_value = 2432, .max_power = 20, }; static struct ieee80211_rate bitrates_2ghz[] = { { .bitrate = 10 }, { .bitrate = 20 }, { .bitrate = 55 }, { .bitrate = 110 }, { .bitrate = 60 }, { .bitrate = 120 }, { .bitrate = 240 }, }; static struct ieee80211_supported_band band_2ghz = { .channels = &channel_2ghz, .bitrates = bitrates_2ghz, .band = NL80211_BAND_2GHZ, .n_channels = 1, .n_bitrates = ARRAY_SIZE(bitrates_2ghz), .ht_cap = { .ht_supported = true, .cap = IEEE80211_HT_CAP_SUP_WIDTH_20_40 | IEEE80211_HT_CAP_GRN_FLD | IEEE80211_HT_CAP_SGI_20 | IEEE80211_HT_CAP_SGI_40 | IEEE80211_HT_CAP_DSSSCCK40, .ampdu_factor = 0x3, .ampdu_density = 0x6, .mcs = { .rx_mask = {0xff, 0xff}, .tx_params = IEEE80211_HT_MCS_TX_DEFINED, }, }, }; static struct ieee80211_channel channel_5ghz = { .band = NL80211_BAND_5GHZ, .center_freq = 5240, .hw_value = 5240, .max_power = 20, }; static struct ieee80211_rate bitrates_5ghz[] = { { .bitrate = 60 }, { .bitrate = 120 }, { .bitrate = 240 }, }; #define RX_MCS_MAP (IEEE80211_VHT_MCS_SUPPORT_0_9 << 0 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 2 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 4 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 6 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 8 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 10 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 12 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 14) #define TX_MCS_MAP (IEEE80211_VHT_MCS_SUPPORT_0_9 << 0 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 2 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 4 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 6 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 8 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 10 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 12 | \ IEEE80211_VHT_MCS_SUPPORT_0_9 << 14) static struct ieee80211_supported_band band_5ghz = { .channels = &channel_5ghz, .bitrates = bitrates_5ghz, .band = NL80211_BAND_5GHZ, .n_channels = 1, .n_bitrates = ARRAY_SIZE(bitrates_5ghz), .ht_cap = { .ht_supported = true, .cap = IEEE80211_HT_CAP_SUP_WIDTH_20_40 | IEEE80211_HT_CAP_GRN_FLD | IEEE80211_HT_CAP_SGI_20 | IEEE80211_HT_CAP_SGI_40 | IEEE80211_HT_CAP_DSSSCCK40, .ampdu_factor = 0x3, .ampdu_density = 0x6, .mcs = { .rx_mask = {0xff, 0xff}, .tx_params = IEEE80211_HT_MCS_TX_DEFINED, }, }, .vht_cap = { .vht_supported = true, .cap = IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_11454 | IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ | IEEE80211_VHT_CAP_RXLDPC | IEEE80211_VHT_CAP_SHORT_GI_80 | IEEE80211_VHT_CAP_SHORT_GI_160 | IEEE80211_VHT_CAP_TXSTBC | IEEE80211_VHT_CAP_RXSTBC_1 | IEEE80211_VHT_CAP_RXSTBC_2 | IEEE80211_VHT_CAP_RXSTBC_3 | IEEE80211_VHT_CAP_RXSTBC_4 | IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK, .vht_mcs = { .rx_mcs_map = cpu_to_le16(RX_MCS_MAP), .tx_mcs_map = cpu_to_le16(TX_MCS_MAP), } }, }; /* Assigned at module init. Guaranteed locally-administered and unicast. */ static u8 fake_router_bssid[ETH_ALEN] __ro_after_init = {}; /* Called with the rtnl lock held. */ static int virt_wifi_scan(struct wiphy *wiphy, struct cfg80211_scan_request *request) { struct virt_wifi_wiphy_priv *priv = wiphy_priv(wiphy); wiphy_debug(wiphy, "scan\n"); if (priv->scan_request || priv->being_deleted) return -EBUSY; priv->scan_request = request; schedule_delayed_work(&priv->scan_result, HZ * 2); return 0; } /* Acquires and releases the rdev BSS lock. */ static void virt_wifi_scan_result(struct work_struct *work) { struct { u8 tag; u8 len; u8 ssid[8]; } __packed ssid = { .tag = WLAN_EID_SSID, .len = 8, .ssid = "VirtWifi", }; struct cfg80211_bss *informed_bss; struct virt_wifi_wiphy_priv *priv = container_of(work, struct virt_wifi_wiphy_priv, scan_result.work); struct wiphy *wiphy = priv_to_wiphy(priv); struct cfg80211_scan_info scan_info = { .aborted = false }; informed_bss = cfg80211_inform_bss(wiphy, &channel_5ghz, CFG80211_BSS_FTYPE_PRESP, fake_router_bssid, ktime_get_boot_ns(), WLAN_CAPABILITY_ESS, 0, (void *)&ssid, sizeof(ssid), DBM_TO_MBM(-50), GFP_KERNEL); cfg80211_put_bss(wiphy, informed_bss); /* Schedules work which acquires and releases the rtnl lock. */ cfg80211_scan_done(priv->scan_request, &scan_info); priv->scan_request = NULL; } /* May acquire and release the rdev BSS lock. */ static void virt_wifi_cancel_scan(struct wiphy *wiphy) { struct virt_wifi_wiphy_priv *priv = wiphy_priv(wiphy); cancel_delayed_work_sync(&priv->scan_result); /* Clean up dangling callbacks if necessary. */ if (priv->scan_request) { struct cfg80211_scan_info scan_info = { .aborted = true }; /* Schedules work which acquires and releases the rtnl lock. */ cfg80211_scan_done(priv->scan_request, &scan_info); priv->scan_request = NULL; } } struct virt_wifi_netdev_priv { struct delayed_work connect; struct net_device *lowerdev; struct net_device *upperdev; u32 tx_packets; u32 tx_failed; u8 connect_requested_bss[ETH_ALEN]; bool is_up; bool is_connected; bool being_deleted; }; /* Called with the rtnl lock held. */ static int virt_wifi_connect(struct wiphy *wiphy, struct net_device *netdev, struct cfg80211_connect_params *sme) { struct virt_wifi_netdev_priv *priv = netdev_priv(netdev); bool could_schedule; if (priv->being_deleted || !priv->is_up) return -EBUSY; could_schedule = schedule_delayed_work(&priv->connect, HZ * 2); if (!could_schedule) return -EBUSY; if (sme->bssid) ether_addr_copy(priv->connect_requested_bss, sme->bssid); else eth_zero_addr(priv->connect_requested_bss); wiphy_debug(wiphy, "connect\n"); return 0; } /* Acquires and releases the rdev event lock. */ static void virt_wifi_connect_complete(struct work_struct *work) { struct virt_wifi_netdev_priv *priv = container_of(work, struct virt_wifi_netdev_priv, connect.work); u8 *requested_bss = priv->connect_requested_bss; bool has_addr = !is_zero_ether_addr(requested_bss); bool right_addr = ether_addr_equal(requested_bss, fake_router_bssid); u16 status = WLAN_STATUS_SUCCESS; if (!priv->is_up || (has_addr && !right_addr)) status = WLAN_STATUS_UNSPECIFIED_FAILURE; else priv->is_connected = true; /* Schedules an event that acquires the rtnl lock. */ cfg80211_connect_result(priv->upperdev, requested_bss, NULL, 0, NULL, 0, status, GFP_KERNEL); netif_carrier_on(priv->upperdev); } /* May acquire and release the rdev event lock. */ static void virt_wifi_cancel_connect(struct net_device *netdev) { struct virt_wifi_netdev_priv *priv = netdev_priv(netdev); /* If there is work pending, clean up dangling callbacks. */ if (cancel_delayed_work_sync(&priv->connect)) { /* Schedules an event that acquires the rtnl lock. */ cfg80211_connect_result(priv->upperdev, priv->connect_requested_bss, NULL, 0, NULL, 0, WLAN_STATUS_UNSPECIFIED_FAILURE, GFP_KERNEL); } } /* Called with the rtnl lock held. Acquires the rdev event lock. */ static int virt_wifi_disconnect(struct wiphy *wiphy, struct net_device *netdev, u16 reason_code) { struct virt_wifi_netdev_priv *priv = netdev_priv(netdev); if (priv->being_deleted) return -EBUSY; wiphy_debug(wiphy, "disconnect\n"); virt_wifi_cancel_connect(netdev); cfg80211_disconnected(netdev, reason_code, NULL, 0, true, GFP_KERNEL); priv->is_connected = false; netif_carrier_off(netdev); return 0; } /* Called with the rtnl lock held. */ static int virt_wifi_get_station(struct wiphy *wiphy, struct net_device *dev, const u8 *mac, struct station_info *sinfo) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); wiphy_debug(wiphy, "get_station\n"); if (!priv->is_connected || !ether_addr_equal(mac, fake_router_bssid)) return -ENOENT; sinfo->filled = BIT_ULL(NL80211_STA_INFO_TX_PACKETS) | BIT_ULL(NL80211_STA_INFO_TX_FAILED) | BIT_ULL(NL80211_STA_INFO_SIGNAL) | BIT_ULL(NL80211_STA_INFO_TX_BITRATE); sinfo->tx_packets = priv->tx_packets; sinfo->tx_failed = priv->tx_failed; /* For CFG80211_SIGNAL_TYPE_MBM, value is expressed in _dBm_ */ sinfo->signal = -50; sinfo->txrate = (struct rate_info) { .legacy = 10, /* units are 100kbit/s */ }; return 0; } /* Called with the rtnl lock held. */ static int virt_wifi_dump_station(struct wiphy *wiphy, struct net_device *dev, int idx, u8 *mac, struct station_info *sinfo) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); wiphy_debug(wiphy, "dump_station\n"); if (idx != 0 || !priv->is_connected) return -ENOENT; ether_addr_copy(mac, fake_router_bssid); return virt_wifi_get_station(wiphy, dev, fake_router_bssid, sinfo); } static const struct cfg80211_ops virt_wifi_cfg80211_ops = { .scan = virt_wifi_scan, .connect = virt_wifi_connect, .disconnect = virt_wifi_disconnect, .get_station = virt_wifi_get_station, .dump_station = virt_wifi_dump_station, }; /* Acquires and releases the rtnl lock. */ static struct wiphy *virt_wifi_make_wiphy(void) { struct wiphy *wiphy; struct virt_wifi_wiphy_priv *priv; int err; wiphy = wiphy_new(&virt_wifi_cfg80211_ops, sizeof(*priv)); if (!wiphy) return NULL; wiphy->max_scan_ssids = 4; wiphy->max_scan_ie_len = 1000; wiphy->signal_type = CFG80211_SIGNAL_TYPE_MBM; wiphy->bands[NL80211_BAND_2GHZ] = &band_2ghz; wiphy->bands[NL80211_BAND_5GHZ] = &band_5ghz; wiphy->bands[NL80211_BAND_60GHZ] = NULL; wiphy->interface_modes = BIT(NL80211_IFTYPE_STATION); priv = wiphy_priv(wiphy); priv->being_deleted = false; priv->scan_request = NULL; INIT_DELAYED_WORK(&priv->scan_result, virt_wifi_scan_result); err = wiphy_register(wiphy); if (err < 0) { wiphy_free(wiphy); return NULL; } return wiphy; } /* Acquires and releases the rtnl lock. */ static void virt_wifi_destroy_wiphy(struct wiphy *wiphy) { struct virt_wifi_wiphy_priv *priv; WARN(!wiphy, "%s called with null wiphy", __func__); if (!wiphy) return; priv = wiphy_priv(wiphy); priv->being_deleted = true; virt_wifi_cancel_scan(wiphy); if (wiphy->registered) wiphy_unregister(wiphy); wiphy_free(wiphy); } /* Enters and exits a RCU-bh critical section. */ static netdev_tx_t virt_wifi_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); priv->tx_packets++; if (!priv->is_connected) { priv->tx_failed++; return NET_XMIT_DROP; } skb->dev = priv->lowerdev; return dev_queue_xmit(skb); } /* Called with rtnl lock held. */ static int virt_wifi_net_device_open(struct net_device *dev) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); priv->is_up = true; return 0; } /* Called with rtnl lock held. */ static int virt_wifi_net_device_stop(struct net_device *dev) { struct virt_wifi_netdev_priv *n_priv = netdev_priv(dev); struct virt_wifi_wiphy_priv *w_priv; n_priv->is_up = false; if (!dev->ieee80211_ptr) return 0; w_priv = wiphy_priv(dev->ieee80211_ptr->wiphy); virt_wifi_cancel_scan(dev->ieee80211_ptr->wiphy); virt_wifi_cancel_connect(dev); netif_carrier_off(dev); return 0; } static const struct net_device_ops virt_wifi_ops = { .ndo_start_xmit = virt_wifi_start_xmit, .ndo_open = virt_wifi_net_device_open, .ndo_stop = virt_wifi_net_device_stop, }; /* Invoked as part of rtnl lock release. */ static void virt_wifi_net_device_destructor(struct net_device *dev) { /* Delayed past dellink to allow nl80211 to react to the device being * deleted. */ kfree(dev->ieee80211_ptr); dev->ieee80211_ptr = NULL; free_netdev(dev); } /* No lock interaction. */ static void virt_wifi_setup(struct net_device *dev) { ether_setup(dev); dev->netdev_ops = &virt_wifi_ops; dev->destructor = virt_wifi_net_device_destructor; } /* Called in a RCU read critical section from netif_receive_skb */ static rx_handler_result_t virt_wifi_rx_handler(struct sk_buff **pskb) { struct sk_buff *skb = *pskb; struct virt_wifi_netdev_priv *priv = rcu_dereference(skb->dev->rx_handler_data); if (!priv->is_connected) return RX_HANDLER_PASS; /* GFP_ATOMIC because this is a packet interrupt handler. */ skb = skb_share_check(skb, GFP_ATOMIC); if (!skb) { dev_err(&priv->upperdev->dev, "can't skb_share_check\n"); return RX_HANDLER_CONSUMED; } *pskb = skb; skb->dev = priv->upperdev; skb->pkt_type = PACKET_HOST; return RX_HANDLER_ANOTHER; } /* Called with rtnl lock held. */ static int virt_wifi_newlink(struct net *src_net, struct net_device *dev, struct nlattr *tb[], struct nlattr *data[]) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); int err; if (!tb[IFLA_LINK]) return -EINVAL; netif_carrier_off(dev); priv->upperdev = dev; priv->lowerdev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK])); if (!priv->lowerdev) return -ENODEV; if (!tb[IFLA_MTU]) dev->mtu = priv->lowerdev->mtu; else if (dev->mtu > priv->lowerdev->mtu) return -EINVAL; err = netdev_rx_handler_register(priv->lowerdev, virt_wifi_rx_handler, priv); if (err) { dev_err(&priv->lowerdev->dev, "can't netdev_rx_handler_register: %d\n", err); return err; } eth_hw_addr_inherit(dev, priv->lowerdev); netif_stacked_transfer_operstate(priv->lowerdev, dev); SET_NETDEV_DEV(dev, &priv->lowerdev->dev); dev->ieee80211_ptr = kzalloc(sizeof(*dev->ieee80211_ptr), GFP_KERNEL); if (!dev->ieee80211_ptr) { err = -ENOMEM; goto remove_handler; } dev->ieee80211_ptr->iftype = NL80211_IFTYPE_STATION; dev->ieee80211_ptr->wiphy = common_wiphy; err = register_netdevice(dev); if (err) { dev_err(&priv->lowerdev->dev, "can't register_netdevice: %d\n", err); goto free_wireless_dev; } err = netdev_upper_dev_link(priv->lowerdev, dev); if (err) { dev_err(&priv->lowerdev->dev, "can't netdev_upper_dev_link: %d\n", err); goto unregister_netdev; } priv->being_deleted = false; priv->is_connected = false; priv->is_up = false; INIT_DELAYED_WORK(&priv->connect, virt_wifi_connect_complete); return 0; unregister_netdev: unregister_netdevice(dev); free_wireless_dev: kfree(dev->ieee80211_ptr); dev->ieee80211_ptr = NULL; remove_handler: netdev_rx_handler_unregister(priv->lowerdev); return err; } /* Called with rtnl lock held. */ static void virt_wifi_dellink(struct net_device *dev, struct list_head *head) { struct virt_wifi_netdev_priv *priv = netdev_priv(dev); if (dev->ieee80211_ptr) virt_wifi_cancel_scan(dev->ieee80211_ptr->wiphy); priv->being_deleted = true; virt_wifi_cancel_connect(dev); netif_carrier_off(dev); netdev_rx_handler_unregister(priv->lowerdev); netdev_upper_dev_unlink(priv->lowerdev, dev); unregister_netdevice_queue(dev, head); /* Deleting the wiphy is handled in the module destructor. */ } static struct rtnl_link_ops virt_wifi_link_ops = { .kind = "virt_wifi", .setup = virt_wifi_setup, .newlink = virt_wifi_newlink, .dellink = virt_wifi_dellink, .priv_size = sizeof(struct virt_wifi_netdev_priv), }; /* Acquires and releases the rtnl lock. */ static int __init virt_wifi_init_module(void) { int err; /* Guaranteed to be locallly-administered and not multicast. */ eth_random_addr(fake_router_bssid); common_wiphy = virt_wifi_make_wiphy(); if (!common_wiphy) return -ENOMEM; err = rtnl_link_register(&virt_wifi_link_ops); if (err) virt_wifi_destroy_wiphy(common_wiphy); return err; } /* Acquires and releases the rtnl lock. */ static void __exit virt_wifi_cleanup_module(void) { /* Will delete any devices that depend on the wiphy. */ rtnl_link_unregister(&virt_wifi_link_ops); virt_wifi_destroy_wiphy(common_wiphy); } module_init(virt_wifi_init_module); module_exit(virt_wifi_cleanup_module); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Cody Schuffelen "); MODULE_DESCRIPTION("Driver for a wireless wrapper of ethernet devices"); MODULE_ALIAS_RTNL_LINK("virt_wifi");