From b2e7771e556917cc301a3308561f49b2b2272c07 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Wed, 26 Sep 2007 15:19:39 +0200 Subject: [PATCH] [PATCH] mac80211: pass frames to monitor interfaces early This makes mac80211 pass all frames to monitor interfaces early before all receive processing with the benefit that only a single copy needs to be made, all monitors can receive clones of the skb and if the frame will be discarded we don't even need to make a single copy. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/rx.c | 350 ++++++++++++++++++++++++++++++---------------- 1 file changed, 226 insertions(+), 124 deletions(-) diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index cb44a9db0e1..a0dfafb4f38 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -25,6 +25,207 @@ #include "tkip.h" #include "wme.h" +/* + * monitor mode reception + * + * This function cleans up the SKB, i.e. it removes all the stuff + * only useful for monitoring. + */ +static struct sk_buff *remove_monitor_info(struct ieee80211_local *local, + struct sk_buff *skb, + int rtap_len) +{ + skb_pull(skb, rtap_len); + + if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) { + if (likely(skb->len > FCS_LEN)) + skb_trim(skb, skb->len - FCS_LEN); + else { + /* driver bug */ + WARN_ON(1); + dev_kfree_skb(skb); + skb = NULL; + } + } + + return skb; +} + +static inline int should_drop_frame(struct ieee80211_rx_status *status, + struct sk_buff *skb, + int present_fcs_len, + int radiotap_len) +{ + struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data; + + if (status->flag & (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC)) + return 1; + if (unlikely(skb->len < 16 + present_fcs_len + radiotap_len)) + return 1; + if ((hdr->frame_control & cpu_to_le16(IEEE80211_FCTL_FTYPE)) == + cpu_to_le16(IEEE80211_FTYPE_CTL)) + return 1; + return 0; +} + +/* + * This function copies a received frame to all monitor interfaces and + * returns a cleaned-up SKB that no longer includes the FCS nor the + * radiotap header the driver might have added. + */ +static struct sk_buff * +ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb, + struct ieee80211_rx_status *status) +{ + struct ieee80211_sub_if_data *sdata; + struct ieee80211_rate *rate; + int needed_headroom = 0; + struct ieee80211_rtap_hdr { + struct ieee80211_radiotap_header hdr; + u8 flags; + u8 rate; + __le16 chan_freq; + __le16 chan_flags; + u8 antsignal; + u8 padding_for_rxflags; + __le16 rx_flags; + } __attribute__ ((packed)) *rthdr; + struct sk_buff *skb, *skb2; + struct net_device *prev_dev = NULL; + int present_fcs_len = 0; + int rtap_len = 0; + + /* + * First, we may need to make a copy of the skb because + * (1) we need to modify it for radiotap (if not present), and + * (2) the other RX handlers will modify the skb we got. + * + * We don't need to, of course, if we aren't going to return + * the SKB because it has a bad FCS/PLCP checksum. + */ + if (status->flag & RX_FLAG_RADIOTAP) + rtap_len = ieee80211_get_radiotap_len(origskb->data); + else + needed_headroom = sizeof(*rthdr); + + if (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) + present_fcs_len = FCS_LEN; + + if (!local->monitors) { + if (should_drop_frame(status, origskb, present_fcs_len, + rtap_len)) { + dev_kfree_skb(origskb); + return NULL; + } + + return remove_monitor_info(local, origskb, rtap_len); + } + + if (should_drop_frame(status, origskb, present_fcs_len, rtap_len)) { + /* only need to expand headroom if necessary */ + skb = origskb; + origskb = NULL; + + /* + * This shouldn't trigger often because most devices have an + * RX header they pull before we get here, and that should + * be big enough for our radiotap information. We should + * probably export the length to drivers so that we can have + * them allocate enough headroom to start with. + */ + if (skb_headroom(skb) < needed_headroom && + pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) { + dev_kfree_skb(skb); + return NULL; + } + } else { + /* + * Need to make a copy and possibly remove radiotap header + * and FCS from the original. + */ + skb = skb_copy_expand(origskb, needed_headroom, 0, GFP_ATOMIC); + + origskb = remove_monitor_info(local, origskb, rtap_len); + + if (!skb) + return origskb; + } + + /* if necessary, prepend radiotap information */ + if (!(status->flag & RX_FLAG_RADIOTAP)) { + rthdr = (void *) skb_push(skb, sizeof(*rthdr)); + memset(rthdr, 0, sizeof(*rthdr)); + rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr)); + rthdr->hdr.it_present = + cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) | + (1 << IEEE80211_RADIOTAP_RATE) | + (1 << IEEE80211_RADIOTAP_CHANNEL) | + (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) | + (1 << IEEE80211_RADIOTAP_RX_FLAGS)); + rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ? + IEEE80211_RADIOTAP_F_FCS : 0; + + /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */ + rthdr->rx_flags = 0; + if (status->flag & + (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC)) + rthdr->rx_flags |= + cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS); + + rate = ieee80211_get_rate(local, status->phymode, + status->rate); + if (rate) + rthdr->rate = rate->rate / 5; + + rthdr->chan_freq = cpu_to_le16(status->freq); + + if (status->phymode == MODE_IEEE80211A) + rthdr->chan_flags = + cpu_to_le16(IEEE80211_CHAN_OFDM | + IEEE80211_CHAN_5GHZ); + else + rthdr->chan_flags = + cpu_to_le16(IEEE80211_CHAN_DYN | + IEEE80211_CHAN_2GHZ); + + rthdr->antsignal = status->ssi; + } + + skb_set_mac_header(skb, 0); + skb->ip_summed = CHECKSUM_UNNECESSARY; + skb->pkt_type = PACKET_OTHERHOST; + skb->protocol = htons(ETH_P_802_2); + + list_for_each_entry_rcu(sdata, &local->interfaces, list) { + if (!netif_running(sdata->dev)) + continue; + + if (sdata->type != IEEE80211_IF_TYPE_MNTR) + continue; + + if (prev_dev) { + skb2 = skb_clone(skb, GFP_ATOMIC); + if (skb2) { + skb2->dev = prev_dev; + netif_rx(skb2); + } + } + + prev_dev = sdata->dev; + sdata->dev->stats.rx_packets++; + sdata->dev->stats.rx_bytes += skb->len; + } + + if (prev_dev) { + skb->dev = prev_dev; + netif_rx(skb); + } else + dev_kfree_skb(skb); + + return origskb; +} + + /* pre-rx handlers * * these don't have dev/sdata fields in the rx data @@ -132,100 +333,6 @@ ieee80211_rx_h_if_stats(struct ieee80211_txrx_data *rx) return TXRX_CONTINUE; } -static void -ieee80211_rx_monitor(struct net_device *dev, struct sk_buff *skb, - struct ieee80211_rx_status *status) -{ - struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr); - struct ieee80211_rate *rate; - struct ieee80211_rtap_hdr { - struct ieee80211_radiotap_header hdr; - u8 flags; - u8 rate; - __le16 chan_freq; - __le16 chan_flags; - u8 antsignal; - u8 padding_for_rxflags; - __le16 rx_flags; - } __attribute__ ((packed)) *rthdr; - - skb->dev = dev; - - if (status->flag & RX_FLAG_RADIOTAP) - goto out; - - if (skb_headroom(skb) < sizeof(*rthdr)) { - I802_DEBUG_INC(local->rx_expand_skb_head); - if (pskb_expand_head(skb, sizeof(*rthdr), 0, GFP_ATOMIC)) { - dev_kfree_skb(skb); - return; - } - } - - rthdr = (struct ieee80211_rtap_hdr *) skb_push(skb, sizeof(*rthdr)); - memset(rthdr, 0, sizeof(*rthdr)); - rthdr->hdr.it_len = cpu_to_le16(sizeof(*rthdr)); - rthdr->hdr.it_present = - cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) | - (1 << IEEE80211_RADIOTAP_RATE) | - (1 << IEEE80211_RADIOTAP_CHANNEL) | - (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) | - (1 << IEEE80211_RADIOTAP_RX_FLAGS)); - rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ? - IEEE80211_RADIOTAP_F_FCS : 0; - - /* FIXME: when radiotap gets a 'bad PLCP' flag use it here */ - rthdr->rx_flags = 0; - if (status->flag & - (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC)) - rthdr->rx_flags |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS); - - rate = ieee80211_get_rate(local, status->phymode, status->rate); - if (rate) - rthdr->rate = rate->rate / 5; - - rthdr->chan_freq = cpu_to_le16(status->freq); - rthdr->chan_flags = - status->phymode == MODE_IEEE80211A ? - cpu_to_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ) : - cpu_to_le16(IEEE80211_CHAN_DYN | IEEE80211_CHAN_2GHZ); - rthdr->antsignal = status->ssi; - - out: - dev->stats.rx_packets++; - dev->stats.rx_bytes += skb->len; - - skb_set_mac_header(skb, 0); - skb->ip_summed = CHECKSUM_UNNECESSARY; - skb->pkt_type = PACKET_OTHERHOST; - skb->protocol = htons(ETH_P_802_2); - memset(skb->cb, 0, sizeof(skb->cb)); - netif_rx(skb); -} - -static ieee80211_txrx_result -ieee80211_rx_h_monitor(struct ieee80211_txrx_data *rx) -{ - if (rx->sdata->type == IEEE80211_IF_TYPE_MNTR) { - ieee80211_rx_monitor(rx->dev, rx->skb, rx->u.rx.status); - return TXRX_QUEUED; - } - - /* - * Drop frames with failed FCS/PLCP checksums here, they are only - * relevant for monitor mode, the rest of the stack should never - * see them. - */ - if (rx->u.rx.status->flag & - (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC)) - return TXRX_DROP; - - if (rx->u.rx.status->flag & RX_FLAG_RADIOTAP) - skb_pull(rx->skb, ieee80211_get_radiotap_len(rx->skb->data)); - - return TXRX_CONTINUE; -} - static ieee80211_txrx_result ieee80211_rx_h_passive_scan(struct ieee80211_txrx_data *rx) { @@ -266,10 +373,6 @@ ieee80211_rx_h_check(struct ieee80211_txrx_data *rx) rx->sta->last_seq_ctrl[rx->u.rx.queue] = hdr->seq_ctrl; } - if ((rx->local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS) && - rx->skb->len > FCS_LEN) - skb_trim(rx->skb, rx->skb->len - FCS_LEN); - if (unlikely(rx->skb->len < 16)) { I802_DEBUG_INC(rx->local->rx_handlers_drop_short); return TXRX_DROP; @@ -1264,7 +1367,6 @@ static void ieee80211_rx_michael_mic_report(struct net_device *dev, ieee80211_rx_handler ieee80211_rx_handlers[] = { ieee80211_rx_h_if_stats, - ieee80211_rx_h_monitor, ieee80211_rx_h_passive_scan, ieee80211_rx_h_check, ieee80211_rx_h_load_key, @@ -1371,16 +1473,10 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, struct ieee80211_hdr *hdr; struct ieee80211_txrx_data rx; u16 type; - int radiotap_len = 0, prepres; + int prepres; struct ieee80211_sub_if_data *prev = NULL; struct sk_buff *skb_new; u8 *bssid; - int bogon; - - if (status->flag & RX_FLAG_RADIOTAP) { - radiotap_len = ieee80211_get_radiotap_len(skb->data); - skb_pull(skb, radiotap_len); - } /* * key references and virtual interfaces are protected using RCU @@ -1389,30 +1485,35 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, */ rcu_read_lock(); + /* + * Frames with failed FCS/PLCP checksum are not returned, + * all other frames are returned without radiotap header + * if it was previously present. + * Also, frames with less than 16 bytes are dropped. + */ + skb = ieee80211_rx_monitor(local, skb, status); + if (!skb) { + rcu_read_unlock(); + return; + } + hdr = (struct ieee80211_hdr *) skb->data; memset(&rx, 0, sizeof(rx)); rx.skb = skb; rx.local = local; rx.u.rx.status = status; - rx.fc = skb->len >= 2 ? le16_to_cpu(hdr->frame_control) : 0; + rx.fc = le16_to_cpu(hdr->frame_control); type = rx.fc & IEEE80211_FCTL_FTYPE; - bogon = status->flag & (RX_FLAG_FAILED_FCS_CRC | - RX_FLAG_FAILED_PLCP_CRC); - - if (!bogon && (type == IEEE80211_FTYPE_DATA || - type == IEEE80211_FTYPE_MGMT)) + if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT) local->dot11ReceivedFragmentCount++; - if (!bogon && skb->len >= 16) { - sta = rx.sta = sta_info_get(local, hdr->addr2); - if (sta) { - rx.dev = rx.sta->dev; - rx.sdata = IEEE80211_DEV_TO_SUB_IF(rx.dev); - } - } else - sta = rx.sta = NULL; + sta = rx.sta = sta_info_get(local, hdr->addr2); + if (sta) { + rx.dev = rx.sta->dev; + rx.sdata = IEEE80211_DEV_TO_SUB_IF(rx.dev); + } if ((status->flag & RX_FLAG_MMIC_ERROR)) { ieee80211_rx_michael_mic_report(local->mdev, hdr, sta, &rx); @@ -1427,7 +1528,6 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, goto end; skb = rx.skb; - skb_push(skb, radiotap_len); if (sta && !(sta->flags & (WLAN_STA_WDS | WLAN_STA_ASSOC_AP)) && !local->iff_promiscs && !is_multicast_ether_addr(hdr->addr1)) { rx.flags |= IEEE80211_TXRXD_RXRA_MATCH; @@ -1438,14 +1538,16 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, return; } - bssid = ieee80211_get_bssid(hdr, skb->len - radiotap_len); + bssid = ieee80211_get_bssid(hdr, skb->len); list_for_each_entry_rcu(sdata, &local->interfaces, list) { - rx.flags |= IEEE80211_TXRXD_RXRA_MATCH; - if (!netif_running(sdata->dev)) continue; + if (sdata->type == IEEE80211_IF_TYPE_MNTR) + continue; + + rx.flags |= IEEE80211_TXRXD_RXRA_MATCH; prepres = prepare_for_handlers(sdata, bssid, &rx, hdr); /* prepare_for_handlers can change sta */ sta = rx.sta; -- 2.41.1