hostap_80211_tx.c

linux内核源码

		printk(KERN_DEBUG "%s: hostap_mgmt_start_xmit: short skb "
		       "(len=%d)\n", dev->name, skb->len);
		kfree_skb(skb);
		return 0;
	}

	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_4addr *) skb->data;
		fc = le16_to_cpu(hdr->frame_ctl);
		if (WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA &&
		    WLAN_FC_GET_STYPE(fc) == 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 0;
}


/* Called only from software IRQ */
static struct sk_buff * hostap_tx_encrypt(struct sk_buff *skb,
					  struct ieee80211_crypt_data *crypt)
{
	struct hostap_interface *iface;
	local_info_t *local;
	struct ieee80211_hdr_4addr *hdr;
	u16 fc;
	int prefix_len, postfix_len, hdr_len, res;
	DECLARE_MAC_BUF(mac);

	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_4addr *) skb->data;
		if (net_ratelimit()) {
			printk(KERN_DEBUG "%s: TKIP countermeasures: dropped "
			       "TX packet to %s\n",
			       local->dev->name, print_mac(mac, 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_4addr *) skb->data;
 	fc = le16_to_cpu(hdr->frame_ctl);
	hdr_len = hostap_80211_get_hdrlen(fc);

	/* 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. */
int hostap_master_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct hostap_interface *iface;
	local_info_t *local;
	int ret = 1;
	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_4addr *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 = 0;
		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[local->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 = 0;
		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_4addr *) skb->data;
 	fc = le16_to_cpu(hdr->frame_ctl);
	switch (tx_ret) {
	case AP_TX_CONTINUE:
		break;
	case AP_TX_CONTINUE_NOT_AUTHORIZED:
		if (local->ieee_802_1x &&
		    WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA &&
		    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 = 0; /* drop packet */
			iface->stats.tx_dropped++;
			goto fail;
		}
		break;
	case AP_TX_DROP:
		ret = 0; /* 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 = 0;
		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_ctl = cpu_to_le16(fc);
	}

	if (WLAN_FC_GET_TYPE(fc) != IEEE80211_FTYPE_DATA) {
		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[local->tx_keyidx]) && !no_encrypt) {
		/* Add ISWEP flag both for firmware and host based encryption
		 */
		fc |= IEEE80211_FCTL_PROTECTED;
		hdr->frame_ctl = cpu_to_le16(fc);
	} else if (local->drop_unencrypted &&
		   WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA &&
		   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 = 0;
		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 = 0;
			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 = 0;
			iface->stats.tx_dropped++;
			goto fail;
		}
	}

	if (local->func->tx == NULL || local->func->tx(skb, dev)) {
		ret = 0;
		iface->stats.tx_dropped++;
	} else {
		ret = 0;
		iface->stats.tx_packets++;
		iface->stats.tx_bytes += skb->len;
	}

 fail:
	if (!ret && 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);