hostap_80211_tx.c

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#include <linux/slab.h>
#include <linux/export.h>

#include "hostap_80211.h"
#include "hostap_common.h"
#include "hostap_wlan.h"
#include "hostap.h"
#include "hostap_ap.h"

/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
static unsigned char rfc1042_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
static unsigned char bridge_tunnel_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
/* No encapsulation header if EtherType < 0x600 (=length) */

void hostap_dump_tx_80211(const char *name, struct sk_buff *skb)
{
    struct ieee80211_hdr *hdr;
    u16 fc;

    hdr = (struct ieee80211_hdr *) skb->data;

    printk(KERN_DEBUG "%s: TX len=%d jiffies=%ld\n",
           name, skb->len, jiffies);

    if (skb->len < 2)
        return;

    fc = le16_to_cpu(hdr->frame_control);
    printk(KERN_DEBUG "   FC=0x%04x (type=%d:%d)%s%s",
           fc, (fc & IEEE80211_FCTL_FTYPE) >> 2,
           (fc & IEEE80211_FCTL_STYPE) >> 4,
           fc & IEEE80211_FCTL_TODS ? " [ToDS]" : "",
           fc & IEEE80211_FCTL_FROMDS ? " [FromDS]" : "");

    if (skb->len < IEEE80211_DATA_HDR3_LEN) {
        printk("\n");
        return;
    }

    printk(" dur=0x%04x seq=0x%04x\n", le16_to_cpu(hdr->duration_id),
           le16_to_cpu(hdr->seq_ctrl));

    printk(KERN_DEBUG "   A1=%pM", hdr->addr1);
    printk(" A2=%pM", hdr->addr2);
    printk(" A3=%pM", hdr->addr3);
    if (skb->len >= 30)
        printk(" A4=%pM", hdr->addr4);
    printk("\n");
}


/* hard_start_xmit function for data interfaces (wlan#, wlan#wds#, wlan#sta)
 * Convert Ethernet header into a suitable IEEE 802.11 header depending on
 * device configuration. */
netdev_tx_t hostap_data_start_xmit(struct sk_buff *skb,
                   struct net_device *dev)
{
    struct hostap_interface *iface;
    local_info_t *local;
    int need_headroom, need_tailroom = 0;
    struct ieee80211_hdr hdr;
    u16 fc, ethertype = 0;
    enum {
        WDS_NO = 0, WDS_OWN_FRAME, WDS_COMPLIANT_FRAME
    } use_wds = WDS_NO;
    u8 *encaps_data;
    int hdr_len, encaps_len, skip_header_bytes;
    int to_assoc_ap = 0;
    struct hostap_skb_tx_data *meta;

    iface = netdev_priv(dev);
    local = iface->local;

    if (skb->len < ETH_HLEN) {
        printk(KERN_DEBUG "%s: hostap_data_start_xmit: short skb "
               "(len=%d)\n", dev->name, skb->len);
        kfree_skb(skb);
        return NETDEV_TX_OK;
    }

    if (local->ddev != dev) {
        use_wds = (local->iw_mode == IW_MODE_MASTER &&
               !(local->wds_type & HOSTAP_WDS_STANDARD_FRAME)) ?
            WDS_OWN_FRAME : WDS_COMPLIANT_FRAME;
        if (dev == local->stadev) {
            to_assoc_ap = 1;
            use_wds = WDS_NO;
        } else if (dev == local->apdev) {
            printk(KERN_DEBUG "%s: prism2_tx: trying to use "
                   "AP device with Ethernet net dev\n", dev->name);
            kfree_skb(skb);
            return NETDEV_TX_OK;
        }
    } else {
        if (local->iw_mode == IW_MODE_REPEAT) {
            printk(KERN_DEBUG "%s: prism2_tx: trying to use "
                   "non-WDS link in Repeater mode\n", dev->name);
            kfree_skb(skb);
            return NETDEV_TX_OK;
        } else if (local->iw_mode == IW_MODE_INFRA &&
               (local->wds_type & HOSTAP_WDS_AP_CLIENT) &&
               memcmp(skb->data + ETH_ALEN, dev->dev_addr,
                  ETH_ALEN) != 0) {
            /* AP client mode: send frames with foreign src addr
             * using 4-addr WDS frames */
            use_wds = WDS_COMPLIANT_FRAME;
        }
    }

    /* Incoming skb->data: dst_addr[6], src_addr[6], proto[2], payload
     * ==>
     * Prism2 TX frame with 802.11 header:
     * txdesc (address order depending on used mode; includes dst_addr and
     * src_addr), possible encapsulation (RFC1042/Bridge-Tunnel;
     * proto[2], payload {, possible addr4[6]} */

    ethertype = (skb->data[12] << 8) | skb->data[13];

    memset(&hdr, 0, sizeof(hdr));

    /* Length of data after IEEE 802.11 header */
    encaps_data = NULL;
    encaps_len = 0;
    skip_header_bytes = ETH_HLEN;
    if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
        encaps_data = bridge_tunnel_header;
        encaps_len = sizeof(bridge_tunnel_header);
        skip_header_bytes -= 2;
    } else if (ethertype >= 0x600) {
        encaps_data = rfc1042_header;
        encaps_len = sizeof(rfc1042_header);
        skip_header_bytes -= 2;
    }

    fc = IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA;
    hdr_len = IEEE80211_DATA_HDR3_LEN;

    if (use_wds != WDS_NO) {
        /* Note! Prism2 station firmware has problems with sending real
         * 802.11 frames with four addresses; until these problems can
         * be fixed or worked around, 4-addr frames needed for WDS are
         * using incompatible format: FromDS flag is not set and the
         * fourth address is added after the frame payload; it is
         * assumed, that the receiving station knows how to handle this
         * frame format */

        if (use_wds == WDS_COMPLIANT_FRAME) {
            fc |= IEEE80211_FCTL_FROMDS | IEEE80211_FCTL_TODS;
            /* From&To DS: Addr1 = RA, Addr2 = TA, Addr3 = DA,
             * Addr4 = SA */
            skb_copy_from_linear_data_offset(skb, ETH_ALEN,
                             &hdr.addr4, ETH_ALEN);
            hdr_len += ETH_ALEN;
        } else {
            /* bogus 4-addr format to workaround Prism2 station
             * f/w bug */
            fc |= IEEE80211_FCTL_TODS;
            /* From DS: Addr1 = DA (used as RA),
             * Addr2 = BSSID (used as TA), Addr3 = SA (used as DA),
             */

            /* SA from skb->data + ETH_ALEN will be added after
             * frame payload; use hdr.addr4 as a temporary buffer
             */
            skb_copy_from_linear_data_offset(skb, ETH_ALEN,
                             &hdr.addr4, ETH_ALEN);
            need_tailroom += ETH_ALEN;
        }

        /* send broadcast and multicast frames to broadcast RA, if
         * configured; otherwise, use unicast RA of the WDS link */
        if ((local->wds_type & HOSTAP_WDS_BROADCAST_RA) &&
            skb->data[0] & 0x01)
            memset(&hdr.addr1, 0xff, ETH_ALEN);
        else if (iface->type == HOSTAP_INTERFACE_WDS)
            memcpy(&hdr.addr1, iface->u.wds.remote_addr,
                   ETH_ALEN);
        else
            memcpy(&hdr.addr1, local->bssid, ETH_ALEN);
        memcpy(&hdr.addr2, dev->dev_addr, ETH_ALEN);
        skb_copy_from_linear_data(skb, &hdr.addr3, ETH_ALEN);
    } else if (local->iw_mode == IW_MODE_MASTER && !to_assoc_ap) {
        fc |= IEEE80211_FCTL_FROMDS;
        /* From DS: Addr1 = DA, Addr2 = BSSID, Addr3 = SA */
        skb_copy_from_linear_data(skb, &hdr.addr1, ETH_ALEN);
        memcpy(&hdr.addr2, dev->dev_addr, ETH_ALEN);
        skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr3,
                         ETH_ALEN);
    } else if (local->iw_mode == IW_MODE_INFRA || to_assoc_ap) {
        fc |= IEEE80211_FCTL_TODS;
        /* To DS: Addr1 = BSSID, Addr2 = SA, Addr3 = DA */
        memcpy(&hdr.addr1, to_assoc_ap ?
               local->assoc_ap_addr : local->bssid, ETH_ALEN);
        skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr2,
                         ETH_ALEN);
        skb_copy_from_linear_data(skb, &hdr.addr3, ETH_ALEN);
    } else if (local->iw_mode == IW_MODE_ADHOC) {
        /* not From/To DS: Addr1 = DA, Addr2 = SA, Addr3 = BSSID */
        skb_copy_from_linear_data(skb, &hdr.addr1, ETH_ALEN);
        skb_copy_from_linear_data_offset(skb, ETH_ALEN, &hdr.addr2,
                         ETH_ALEN);
        memcpy(&hdr.addr3, local->bssid, ETH_ALEN);
    }

    hdr.frame_control = cpu_to_le16(fc);

    skb_pull(skb, skip_header_bytes);
    need_headroom = local->func->need_tx_headroom + hdr_len + encaps_len;
    if (skb_tailroom(skb) < need_tailroom) {
        skb = skb_unshare(skb, GFP_ATOMIC);
        if (skb == NULL) {
            iface->stats.tx_dropped++;
            return NETDEV_TX_OK;
        }
        if (pskb_expand_head(skb, need_headroom, need_tailroom,
                     GFP_ATOMIC)) {
            kfree_skb(skb);
            iface->stats.tx_dropped++;
            return NETDEV_TX_OK;
        }
    } else if (skb_headroom(skb) < need_headroom) {
        struct sk_buff *tmp = skb;
        skb = skb_realloc_headroom(skb, need_headroom);
        kfree_skb(tmp);
        if (skb == NULL) {
            iface->stats.tx_dropped++;
            return NETDEV_TX_OK;
        }
    } else {
        skb = skb_unshare(skb, GFP_ATOMIC);
        if (skb == NULL) {
            iface->stats.tx_dropped++;
            return NETDEV_TX_OK;
        }
    }

    if (encaps_data)
        memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
    memcpy(skb_push(skb, hdr_len), &hdr, hdr_len);
    if (use_wds == WDS_OWN_FRAME) {
        memcpy(skb_put(skb, ETH_ALEN), &hdr.addr4, ETH_ALEN);
    }

    iface->stats.tx_packets++;
    iface->stats.tx_bytes += skb->len;

    skb_reset_mac_header(skb);
    meta = (struct hostap_skb_tx_data *) skb->cb;
    memset(meta, 0, sizeof(*meta));
    meta->magic = HOSTAP_SKB_TX_DATA_MAGIC;
    if (use_wds)
        meta->flags |= HOSTAP_TX_FLAGS_WDS;
    meta->ethertype = ethertype;
    meta->iface = iface;

    /* Send IEEE 802.11 encapsulated frame using the master radio device */
    skb->dev = local->dev;
    dev_queue_xmit(skb);
    return NETDEV_TX_OK;
}


/* hard_start_xmit function for hostapd wlan#ap interfaces */
netdev_tx_t hostap_mgmt_start_xmit(struct sk_buff *skb,
                   struct net_device *dev)
{
    struct hostap_interface *iface;
    local_info_t *local;
    struct hostap_skb_tx_data *meta;
    struct ieee80211_hdr *hdr;
    u16 fc;

    iface = netdev_priv(dev);
    local = iface->local;

    if (skb->len < 10) {
        printk(KERN_DEBUG "%s: hostap_mgmt_start_xmit: short skb "
               "(len=%d)\n", dev->name, skb->len);
        kfree_skb(skb);
        return NETDEV_TX_OK;
    }

    iface->stats.tx_packets++;
    iface->stats.tx_bytes += skb->len;

    meta = (struct hostap_skb_tx_data *) skb->cb;
    memset(meta, 0, sizeof(*meta));
    meta->magic = HOSTAP_SKB_TX_DATA_MAGIC;
    meta->iface = iface;

    if (skb->len >= IEEE80211_DATA_HDR3_LEN + sizeof(rfc1042_header) + 2) {
        hdr = (struct ieee80211_hdr *) skb->data;
        fc = le16_to_cpu(hdr->frame_control);
        if (ieee80211_is_data(hdr->frame_control) &&
            (fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_DATA) {
            u8 *pos = &skb->data[IEEE80211_DATA_HDR3_LEN +
                         sizeof(rfc1042_header)];
            meta->ethertype = (pos[0] << 8) | pos[1];
        }
    }

    /* Send IEEE 802.11 encapsulated frame using the master radio device */
    skb->dev = local->dev;
    dev_queue_xmit(skb);
    return NETDEV_TX_OK;
}


/* Called only from software IRQ */
static struct sk_buff * hostap_tx_encrypt(struct sk_buff *skb,
                      struct lib80211_crypt_data *crypt)
{
    struct hostap_interface *iface;
    local_info_t *local;
    struct ieee80211_hdr *hdr;
    int prefix_len, postfix_len, hdr_len, res;

    iface = netdev_priv(skb->dev);
    local = iface->local;

    if (skb->len < IEEE80211_DATA_HDR3_LEN) {
        kfree_skb(skb);
        return NULL;
    }

    if (local->tkip_countermeasures &&
        strcmp(crypt->ops->name, "TKIP") == 0) {
        hdr = (struct ieee80211_hdr *) skb->data;
        if (net_ratelimit()) {
            printk(KERN_DEBUG "%s: TKIP countermeasures: dropped "
                   "TX packet to %pM\n",
                   local->dev->name, hdr->addr1);
        }
        kfree_skb(skb);
        return NULL;
    }

    skb = skb_unshare(skb, GFP_ATOMIC);
    if (skb == NULL)
        return NULL;

    prefix_len = crypt->ops->extra_mpdu_prefix_len +
        crypt->ops->extra_msdu_prefix_len;
    postfix_len = crypt->ops->extra_mpdu_postfix_len +
        crypt->ops->extra_msdu_postfix_len;
    if ((skb_headroom(skb) < prefix_len ||
         skb_tailroom(skb) < postfix_len) &&
        pskb_expand_head(skb, prefix_len, postfix_len, GFP_ATOMIC)) {
        kfree_skb(skb);
        return NULL;
    }

    hdr = (struct ieee80211_hdr *) skb->data;
    hdr_len = hostap_80211_get_hdrlen(hdr->frame_control);

    /* Host-based IEEE 802.11 fragmentation for TX is not yet supported, so
     * call both MSDU and MPDU encryption functions from here. */
    atomic_inc(&crypt->refcnt);
    res = 0;
    if (crypt->ops->encrypt_msdu)
        res = crypt->ops->encrypt_msdu(skb, hdr_len, crypt->priv);
    if (res == 0 && crypt->ops->encrypt_mpdu)
        res = crypt->ops->encrypt_mpdu(skb, hdr_len, crypt->priv);
    atomic_dec(&crypt->refcnt);
    if (res < 0) {
        kfree_skb(skb);
        return NULL;
    }

    return skb;
}


/* hard_start_xmit function for master radio interface wifi#.
 * AP processing (TX rate control, power save buffering, etc.).
 * Use hardware TX function to send the frame. */
netdev_tx_t hostap_master_start_xmit(struct sk_buff *skb,
                     struct net_device *dev)
{
    struct hostap_interface *iface;
    local_info_t *local;
    netdev_tx_t ret = NETDEV_TX_BUSY;
    u16 fc;
    struct hostap_tx_data tx;
    ap_tx_ret tx_ret;
    struct hostap_skb_tx_data *meta;
    int no_encrypt = 0;
    struct ieee80211_hdr *hdr;

    iface = netdev_priv(dev);
    local = iface->local;

    tx.skb = skb;
    tx.sta_ptr = NULL;

    meta = (struct hostap_skb_tx_data *) skb->cb;
    if (meta->magic != HOSTAP_SKB_TX_DATA_MAGIC) {
        printk(KERN_DEBUG "%s: invalid skb->cb magic (0x%08x, "
               "expected 0x%08x)\n",
               dev->name, meta->magic, HOSTAP_SKB_TX_DATA_MAGIC);
        ret = NETDEV_TX_OK;
        iface->stats.tx_dropped++;
        goto fail;
    }

    if (local->host_encrypt) {
        /* Set crypt to default algorithm and key; will be replaced in
         * AP code if STA has own alg/key */
        tx.crypt = local->crypt_info.crypt[local->crypt_info.tx_keyidx];
        tx.host_encrypt = 1;
    } else {
        tx.crypt = NULL;
        tx.host_encrypt = 0;
    }

    if (skb->len < 24) {
        printk(KERN_DEBUG "%s: hostap_master_start_xmit: short skb "
               "(len=%d)\n", dev->name, skb->len);
        ret = NETDEV_TX_OK;
        iface->stats.tx_dropped++;
        goto fail;
    }

    /* FIX (?):
     * Wi-Fi 802.11b test plan suggests that AP should ignore power save
     * bit in authentication and (re)association frames and assume tha
     * STA remains awake for the response. */
    tx_ret = hostap_handle_sta_tx(local, &tx);
    skb = tx.skb;
    meta = (struct hostap_skb_tx_data *) skb->cb;
    hdr = (struct ieee80211_hdr *) skb->data;
    fc = le16_to_cpu(hdr->frame_control);
    switch (tx_ret) {
    case AP_TX_CONTINUE:
        break;
    case AP_TX_CONTINUE_NOT_AUTHORIZED:
        if (local->ieee_802_1x &&
            ieee80211_is_data(hdr->frame_control) &&
            meta->ethertype != ETH_P_PAE &&
            !(meta->flags & HOSTAP_TX_FLAGS_WDS)) {
            printk(KERN_DEBUG "%s: dropped frame to unauthorized "
                   "port (IEEE 802.1X): ethertype=0x%04x\n",
                   dev->name, meta->ethertype);
            hostap_dump_tx_80211(dev->name, skb);

            ret = NETDEV_TX_OK; /* drop packet */
            iface->stats.tx_dropped++;
            goto fail;
        }
        break;
    case AP_TX_DROP:
        ret = NETDEV_TX_OK; /* drop packet */
        iface->stats.tx_dropped++;
        goto fail;
    case AP_TX_RETRY:
        goto fail;
    case AP_TX_BUFFERED:
        /* do not free skb here, it will be freed when the
         * buffered frame is sent/timed out */
        ret = NETDEV_TX_OK;
        goto tx_exit;
    }

    /* Request TX callback if protocol version is 2 in 802.11 header;
     * this version 2 is a special case used between hostapd and kernel
     * driver */
    if (((fc & IEEE80211_FCTL_VERS) == BIT(1)) &&
        local->ap && local->ap->tx_callback_idx && meta->tx_cb_idx == 0) {
        meta->tx_cb_idx = local->ap->tx_callback_idx;

        /* remove special version from the frame header */
        fc &= ~IEEE80211_FCTL_VERS;
        hdr->frame_control = cpu_to_le16(fc);
    }

    if (!ieee80211_is_data(hdr->frame_control)) {
        no_encrypt = 1;
        tx.crypt = NULL;
    }

    if (local->ieee_802_1x && meta->ethertype == ETH_P_PAE && tx.crypt &&
        !(fc & IEEE80211_FCTL_PROTECTED)) {
        no_encrypt = 1;
        PDEBUG(DEBUG_EXTRA2, "%s: TX: IEEE 802.1X - passing "
               "unencrypted EAPOL frame\n", dev->name);
        tx.crypt = NULL; /* no encryption for IEEE 802.1X frames */
    }

    if (tx.crypt && (!tx.crypt->ops || !tx.crypt->ops->encrypt_mpdu))
        tx.crypt = NULL;
    else if ((tx.crypt ||
         local->crypt_info.crypt[local->crypt_info.tx_keyidx]) &&
         !no_encrypt) {
        /* Add ISWEP flag both for firmware and host based encryption
         */
        fc |= IEEE80211_FCTL_PROTECTED;
        hdr->frame_control = cpu_to_le16(fc);
    } else if (local->drop_unencrypted &&
           ieee80211_is_data(hdr->frame_control) &&
           meta->ethertype != ETH_P_PAE) {
        if (net_ratelimit()) {
            printk(KERN_DEBUG "%s: dropped unencrypted TX data "
                   "frame (drop_unencrypted=1)\n", dev->name);
        }
        iface->stats.tx_dropped++;
        ret = NETDEV_TX_OK;
        goto fail;
    }

    if (tx.crypt) {
        skb = hostap_tx_encrypt(skb, tx.crypt);
        if (skb == NULL) {
            printk(KERN_DEBUG "%s: TX - encryption failed\n",
                   dev->name);
            ret = NETDEV_TX_OK;
            goto fail;
        }
        meta = (struct hostap_skb_tx_data *) skb->cb;
        if (meta->magic != HOSTAP_SKB_TX_DATA_MAGIC) {
            printk(KERN_DEBUG "%s: invalid skb->cb magic (0x%08x, "
                   "expected 0x%08x) after hostap_tx_encrypt\n",
                   dev->name, meta->magic,
                   HOSTAP_SKB_TX_DATA_MAGIC);
            ret = NETDEV_TX_OK;
            iface->stats.tx_dropped++;
            goto fail;
        }
    }

    if (local->func->tx == NULL || local->func->tx(skb, dev)) {
        ret = NETDEV_TX_OK;
        iface->stats.tx_dropped++;
    } else {
        ret = NETDEV_TX_OK;
        iface->stats.tx_packets++;
        iface->stats.tx_bytes += skb->len;
    }

 fail:
    if (ret == NETDEV_TX_OK && skb)
        dev_kfree_skb(skb);
 tx_exit:
    if (tx.sta_ptr)
        hostap_handle_sta_release(tx.sta_ptr);
    return ret;
}


EXPORT_SYMBOL(hostap_master_start_xmit);