Commit 73b9f03a authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
Browse files

mac80211: parse radiotap header earlier 



We can now move the radiotap header parsing into
ieee80211_monitor_start_xmit(). This moves it out of
the hotpath, and also helps the code since now the
radiotap header will no longer be present in
ieee80211_xmit() etc. which is easier to understand.

Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent a26eb27a

include/net/mac80211.h

+1 −3
Original line number Diff line number Diff line
@@ -349,8 +349,6 @@ struct ieee80211_bss_conf { 
 * @IEEE80211_TX_INTFL_RETRANSMISSION: This frame is being retransmitted

 *	after TX status because the destination was asleep, it must not

 *	be modified again (no seqno assignment, crypto, etc.)

 * @IEEE80211_TX_INTFL_HAS_RADIOTAP: This frame was injected and still

 *	has a radiotap header at skb->data.

 * @IEEE80211_TX_INTFL_NL80211_FRAME_TX: Frame was requested through nl80211

 *	MLME command (internal to mac80211 to figure out whether to send TX

 *	status to user space)
@@ -402,7 +400,7 @@ enum mac80211_tx_control_flags { 
	IEEE80211_TX_CTL_POLL_RESPONSE		= BIT(17),

	IEEE80211_TX_CTL_MORE_FRAMES		= BIT(18),

	IEEE80211_TX_INTFL_RETRANSMISSION	= BIT(19),

	IEEE80211_TX_INTFL_HAS_RADIOTAP		= BIT(20),

	/* hole at 20, use later */

	IEEE80211_TX_INTFL_NL80211_FRAME_TX	= BIT(21),

	IEEE80211_TX_CTL_LDPC			= BIT(22),

	IEEE80211_TX_CTL_STBC			= BIT(23) | BIT(24),

net/mac80211/tx.c

+88 −113
Original line number Diff line number Diff line
@@ -1035,103 +1035,6 @@ ieee80211_tx_h_calculate_duration(struct ieee80211_tx_data *tx) 


/* actual transmit path */



/*

 * deal with packet injection down monitor interface

 * with Radiotap Header -- only called for monitor mode interface

 */

static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,

					  struct sk_buff *skb)

{

	/*

	 * this is the moment to interpret and discard the radiotap header that

	 * must be at the start of the packet injected in Monitor mode

	 *

	 * Need to take some care with endian-ness since radiotap

	 * args are little-endian

	 */



	struct ieee80211_radiotap_iterator iterator;

	struct ieee80211_radiotap_header *rthdr =

		(struct ieee80211_radiotap_header *) skb->data;

	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

	int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,

						   NULL);

	u16 txflags;



	info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |

		       IEEE80211_TX_CTL_DONTFRAG;



	/*

	 * for every radiotap entry that is present

	 * (ieee80211_radiotap_iterator_next returns -ENOENT when no more

	 * entries present, or -EINVAL on error)

	 */



	while (!ret) {

		ret = ieee80211_radiotap_iterator_next(&iterator);



		if (ret)

			continue;



		/* see if this argument is something we can use */

		switch (iterator.this_arg_index) {

		/*

		 * You must take care when dereferencing iterator.this_arg

		 * for multibyte types... the pointer is not aligned.  Use

		 * get_unaligned((type *)iterator.this_arg) to dereference

		 * iterator.this_arg for type "type" safely on all arches.

		*/

		case IEEE80211_RADIOTAP_FLAGS:

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {

				/*

				 * this indicates that the skb we have been

				 * handed has the 32-bit FCS CRC at the end...

				 * we should react to that by snipping it off

				 * because it will be recomputed and added

				 * on transmission

				 */

				if (skb->len < (iterator._max_length + FCS_LEN))

					return false;



				skb_trim(skb, skb->len - FCS_LEN);

			}

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)

				info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)

				info->flags &= ~IEEE80211_TX_CTL_DONTFRAG;

			break;



		case IEEE80211_RADIOTAP_TX_FLAGS:

			txflags = le16_to_cpu(get_unaligned((__le16*)

						iterator.this_arg));

			if (txflags & IEEE80211_RADIOTAP_F_TX_NOACK)

				info->flags |= IEEE80211_TX_CTL_NO_ACK;

			break;



		/*

		 * Please update the file

		 * Documentation/networking/mac80211-injection.txt

		 * when parsing new fields here.

		 */



		default:

			break;

		}

	}



	if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */

		return false;



	/*

	 * remove the radiotap header

	 * iterator->_max_length was sanity-checked against

	 * skb->len by iterator init

	 */

	skb_pull(skb, iterator._max_length);



	return true;

}



static bool ieee80211_tx_prep_agg(struct ieee80211_tx_data *tx,

				  struct sk_buff *skb,

				  struct ieee80211_tx_info *info,
@@ -1205,19 +1108,6 @@ ieee80211_tx_prepare(struct ieee80211_sub_if_data *sdata, 
	tx->sdata = sdata;

	tx->channel = local->hw.conf.channel;



	/* process and remove the injection radiotap header */

	if (unlikely(info->flags & IEEE80211_TX_INTFL_HAS_RADIOTAP)) {

		if (!__ieee80211_parse_tx_radiotap(tx, skb))

			return TX_DROP;



		/*

		 * __ieee80211_parse_tx_radiotap has now removed

		 * the radiotap header that was present and pre-filled

		 * 'tx' with tx control information.

		 */

		info->flags &= ~IEEE80211_TX_INTFL_HAS_RADIOTAP;

	}



	/*

	 * If this flag is set to true anywhere, and we get here,

	 * we are doing the needed processing, so remove the flag
@@ -1559,6 +1449,89 @@ void ieee80211_xmit(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb) 
	rcu_read_unlock();

}



static bool ieee80211_parse_tx_radiotap(struct sk_buff *skb)

{

	struct ieee80211_radiotap_iterator iterator;

	struct ieee80211_radiotap_header *rthdr =

		(struct ieee80211_radiotap_header *) skb->data;

	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

	int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,

						   NULL);

	u16 txflags;



	info->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |

		       IEEE80211_TX_CTL_DONTFRAG;



	/*

	 * for every radiotap entry that is present

	 * (ieee80211_radiotap_iterator_next returns -ENOENT when no more

	 * entries present, or -EINVAL on error)

	 */



	while (!ret) {

		ret = ieee80211_radiotap_iterator_next(&iterator);



		if (ret)

			continue;



		/* see if this argument is something we can use */

		switch (iterator.this_arg_index) {

		/*

		 * You must take care when dereferencing iterator.this_arg

		 * for multibyte types... the pointer is not aligned.  Use

		 * get_unaligned((type *)iterator.this_arg) to dereference

		 * iterator.this_arg for type "type" safely on all arches.

		*/

		case IEEE80211_RADIOTAP_FLAGS:

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS) {

				/*

				 * this indicates that the skb we have been

				 * handed has the 32-bit FCS CRC at the end...

				 * we should react to that by snipping it off

				 * because it will be recomputed and added

				 * on transmission

				 */

				if (skb->len < (iterator._max_length + FCS_LEN))

					return false;



				skb_trim(skb, skb->len - FCS_LEN);

			}

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_WEP)

				info->flags &= ~IEEE80211_TX_INTFL_DONT_ENCRYPT;

			if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FRAG)

				info->flags &= ~IEEE80211_TX_CTL_DONTFRAG;

			break;



		case IEEE80211_RADIOTAP_TX_FLAGS:

			txflags = get_unaligned_le16(iterator.this_arg);

			if (txflags & IEEE80211_RADIOTAP_F_TX_NOACK)

				info->flags |= IEEE80211_TX_CTL_NO_ACK;

			break;



		/*

		 * Please update the file

		 * Documentation/networking/mac80211-injection.txt

		 * when parsing new fields here.

		 */



		default:

			break;

		}

	}



	if (ret != -ENOENT) /* ie, if we didn't simply run out of fields */

		return false;



	/*

	 * remove the radiotap header

	 * iterator->_max_length was sanity-checked against

	 * skb->len by iterator init

	 */

	skb_pull(skb, iterator._max_length);



	return true;

}



netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb,

					 struct net_device *dev)

{
@@ -1646,8 +1619,11 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, 
	memset(info, 0, sizeof(*info));



	info->flags = IEEE80211_TX_CTL_REQ_TX_STATUS |

		      IEEE80211_TX_CTL_INJECTED |

		      IEEE80211_TX_INTFL_HAS_RADIOTAP;

		      IEEE80211_TX_CTL_INJECTED;



	/* process and remove the injection radiotap header */

	if (!ieee80211_parse_tx_radiotap(skb))

		goto fail;



	rcu_read_lock();
@@ -1674,7 +1650,6 @@ netdev_tx_t ieee80211_monitor_start_xmit(struct sk_buff *skb, 
		}

	}



	/* pass the radiotap header up to xmit */

	ieee80211_xmit(sdata, skb);

	rcu_read_unlock();

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