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Commit 33e5a2f7 authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville
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wireless: update radiotap parser



Upstream radiotap has adopted the namespace
proposal David Young made and I then took care
of, for which I had adapted the radiotap parser
as a library outside the kernel. This brings
the in-kernel parser up to speed.

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 69068036
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+64 −19
Original line number Diff line number Diff line
@@ -1561,38 +1561,83 @@ ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
 * Documentation in Documentation/networking/radiotap-headers.txt
 */

struct radiotap_align_size {
	uint8_t align:4, size:4;
};

struct ieee80211_radiotap_namespace {
	const struct radiotap_align_size *align_size;
	int n_bits;
	uint32_t oui;
	uint8_t subns;
};

struct ieee80211_radiotap_vendor_namespaces {
	const struct ieee80211_radiotap_namespace *ns;
	int n_ns;
};

/**
 * struct ieee80211_radiotap_iterator - tracks walk thru present radiotap args
 * @rtheader: pointer to the radiotap header we are walking through
 * @max_length: length of radiotap header in cpu byte ordering
 * @this_arg_index: IEEE80211_RADIOTAP_... index of current arg
 * @this_arg: pointer to current radiotap arg
 * @arg_index: internal next argument index
 * @arg: internal next argument pointer
 * @next_bitmap: internal pointer to next present u32
 * @bitmap_shifter: internal shifter for curr u32 bitmap, b0 set == arg present
 * @this_arg_index: index of current arg, valid after each successful call
 *	to ieee80211_radiotap_iterator_next()
 * @this_arg: pointer to current radiotap arg; it is valid after each
 *	call to ieee80211_radiotap_iterator_next() but also after
 *	ieee80211_radiotap_iterator_init() where it will point to
 *	the beginning of the actual data portion
 * @this_arg_size: length of the current arg, for convenience
 * @current_namespace: pointer to the current namespace definition
 *	(or internally %NULL if the current namespace is unknown)
 * @is_radiotap_ns: indicates whether the current namespace is the default
 *	radiotap namespace or not
 *
 * @overrides: override standard radiotap fields
 * @n_overrides: number of overrides
 *
 * @_rtheader: pointer to the radiotap header we are walking through
 * @_max_length: length of radiotap header in cpu byte ordering
 * @_arg_index: next argument index
 * @_arg: next argument pointer
 * @_next_bitmap: internal pointer to next present u32
 * @_bitmap_shifter: internal shifter for curr u32 bitmap, b0 set == arg present
 * @_vns: vendor namespace definitions
 * @_next_ns_data: beginning of the next namespace's data
 * @_reset_on_ext: internal; reset the arg index to 0 when going to the
 *	next bitmap word
 *
 * Describes the radiotap parser state. Fields prefixed with an underscore
 * must not be used by users of the parser, only by the parser internally.
 */

struct ieee80211_radiotap_iterator {
	struct ieee80211_radiotap_header *rtheader;
	int max_length;
	struct ieee80211_radiotap_header *_rtheader;
	const struct ieee80211_radiotap_vendor_namespaces *_vns;
	const struct ieee80211_radiotap_namespace *current_namespace;

	unsigned char *_arg, *_next_ns_data;
	uint32_t *_next_bitmap;

	unsigned char *this_arg;
	int this_arg_index;
	u8 *this_arg;
	int this_arg_size;

	int arg_index;
	u8 *arg;
	__le32 *next_bitmap;
	u32 bitmap_shifter;
	int is_radiotap_ns;

	int _max_length;
	int _arg_index;
	uint32_t _bitmap_shifter;
	int _reset_on_ext;
};

extern int ieee80211_radiotap_iterator_init(
	struct ieee80211_radiotap_iterator *iterator,
	struct ieee80211_radiotap_header *radiotap_header,
   int max_length);
	int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns);

extern int ieee80211_radiotap_iterator_next(
	struct ieee80211_radiotap_iterator *iterator);


extern const unsigned char rfc1042_header[6];
extern const unsigned char bridge_tunnel_header[6];

+4 −0
Original line number Diff line number Diff line
@@ -198,6 +198,10 @@ enum ieee80211_radiotap_type {
	IEEE80211_RADIOTAP_TX_FLAGS = 15,
	IEEE80211_RADIOTAP_RTS_RETRIES = 16,
	IEEE80211_RADIOTAP_DATA_RETRIES = 17,

	/* valid in every it_present bitmap, even vendor namespaces */
	IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE = 29,
	IEEE80211_RADIOTAP_VENDOR_NAMESPACE = 30,
	IEEE80211_RADIOTAP_EXT = 31
};

+5 −4
Original line number Diff line number Diff line
@@ -1010,7 +1010,8 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
		(struct ieee80211_radiotap_header *) skb->data;
	struct ieee80211_supported_band *sband;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len);
	int ret = ieee80211_radiotap_iterator_init(&iterator, rthdr, skb->len,
						   NULL);

	sband = tx->local->hw.wiphy->bands[tx->channel->band];

@@ -1046,7 +1047,7 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,
				 * because it will be recomputed and added
				 * on transmission
				 */
				if (skb->len < (iterator.max_length + FCS_LEN))
				if (skb->len < (iterator._max_length + FCS_LEN))
					return false;

				skb_trim(skb, skb->len - FCS_LEN);
@@ -1073,10 +1074,10 @@ static bool __ieee80211_parse_tx_radiotap(struct ieee80211_tx_data *tx,

	/*
	 * remove the radiotap header
	 * iterator->max_length was sanity-checked against
	 * iterator->_max_length was sanity-checked against
	 * skb->len by iterator init
	 */
	skb_pull(skb, iterator.max_length);
	skb_pull(skb, iterator._max_length);

	return true;
}
+198 −107
Original line number Diff line number Diff line
@@ -2,6 +2,16 @@
 * Radiotap parser
 *
 * Copyright 2007		Andy Green <andy@warmcat.com>
 * Copyright 2009		Johannes Berg <johannes@sipsolutions.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See COPYING for more details.
 */

#include <net/cfg80211.h>
@@ -10,6 +20,35 @@

/* function prototypes and related defs are in include/net/cfg80211.h */

static const struct radiotap_align_size rtap_namespace_sizes[] = {
	[IEEE80211_RADIOTAP_TSFT] = { .align = 8, .size = 8, },
	[IEEE80211_RADIOTAP_FLAGS] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_RATE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_CHANNEL] = { .align = 2, .size = 4, },
	[IEEE80211_RADIOTAP_FHSS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DBM_ANTNOISE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_LOCK_QUALITY] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_TX_ATTENUATION] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DBM_TX_POWER] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_ANTENNA] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DB_ANTNOISE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_RX_FLAGS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_TX_FLAGS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_RTS_RETRIES] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DATA_RETRIES] = { .align = 1, .size = 1, },
	/*
	 * add more here as they are defined in radiotap.h
	 */
};

static const struct ieee80211_radiotap_namespace radiotap_ns = {
	.n_bits = sizeof(rtap_namespace_sizes) / sizeof(rtap_namespace_sizes[0]),
	.align_size = rtap_namespace_sizes,
};

/**
 * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
 * @iterator: radiotap_iterator to initialize
@@ -52,7 +91,7 @@
int ieee80211_radiotap_iterator_init(
	struct ieee80211_radiotap_iterator *iterator,
	struct ieee80211_radiotap_header *radiotap_header,
    int max_length)
	int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns)
{
	/* Linux only supports version 0 radiotap format */
	if (radiotap_header->it_version)
@@ -62,19 +101,24 @@ int ieee80211_radiotap_iterator_init(
	if (max_length < get_unaligned_le16(&radiotap_header->it_len))
		return -EINVAL;

	iterator->rtheader = radiotap_header;
	iterator->max_length = get_unaligned_le16(&radiotap_header->it_len);
	iterator->arg_index = 0;
	iterator->bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
	iterator->arg = (u8 *)radiotap_header + sizeof(*radiotap_header);
	iterator->this_arg = NULL;
	iterator->_rtheader = radiotap_header;
	iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len);
	iterator->_arg_index = 0;
	iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
	iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header);
	iterator->_reset_on_ext = 0;
	iterator->_next_bitmap = &radiotap_header->it_present;
	iterator->_next_bitmap++;
	iterator->_vns = vns;
	iterator->current_namespace = &radiotap_ns;
	iterator->is_radiotap_ns = 1;

	/* find payload start allowing for extended bitmap(s) */

	if (unlikely(iterator->bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT))) {
		while (get_unaligned_le32(iterator->arg) &
	if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
		while (get_unaligned_le32(iterator->_arg) &
					(1 << IEEE80211_RADIOTAP_EXT)) {
			iterator->arg += sizeof(u32);
			iterator->_arg += sizeof(uint32_t);

			/*
			 * check for insanity where the present bitmaps
@@ -82,12 +126,13 @@ int ieee80211_radiotap_iterator_init(
			 * stated radiotap header length
			 */

			if (((ulong)iterator->arg -
			     (ulong)iterator->rtheader) > iterator->max_length)
			if ((unsigned long)iterator->_arg -
			    (unsigned long)iterator->_rtheader >
			    (unsigned long)iterator->_max_length)
				return -EINVAL;
		}

		iterator->arg += sizeof(u32);
		iterator->_arg += sizeof(uint32_t);

		/*
		 * no need to check again for blowing past stated radiotap
@@ -96,12 +141,36 @@ int ieee80211_radiotap_iterator_init(
		 */
	}

	iterator->this_arg = iterator->_arg;

	/* we are all initialized happily */

	return 0;
}
EXPORT_SYMBOL(ieee80211_radiotap_iterator_init);

static void find_ns(struct ieee80211_radiotap_iterator *iterator,
		    uint32_t oui, uint8_t subns)
{
	int i;

	iterator->current_namespace = NULL;

	if (!iterator->_vns)
		return;

	for (i = 0; i < iterator->_vns->n_ns; i++) {
		if (iterator->_vns->ns[i].oui != oui)
			continue;
		if (iterator->_vns->ns[i].subns != subns)
			continue;

		iterator->current_namespace = &iterator->_vns->ns[i];
		break;
	}
}



/**
 * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
@@ -129,97 +198,78 @@ EXPORT_SYMBOL(ieee80211_radiotap_iterator_init);
int ieee80211_radiotap_iterator_next(
	struct ieee80211_radiotap_iterator *iterator)
{

	/*
	 * small length lookup table for all radiotap types we heard of
	 * starting from b0 in the bitmap, so we can walk the payload
	 * area of the radiotap header
	 *
	 * There is a requirement to pad args, so that args
	 * of a given length must begin at a boundary of that length
	 * -- but note that compound args are allowed (eg, 2 x u16
	 * for IEEE80211_RADIOTAP_CHANNEL) so total arg length is not
	 * a reliable indicator of alignment requirement.
	 *
	 * upper nybble: content alignment for arg
	 * lower nybble: content length for arg
	 */

	static const u8 rt_sizes[] = {
		[IEEE80211_RADIOTAP_TSFT] = 0x88,
		[IEEE80211_RADIOTAP_FLAGS] = 0x11,
		[IEEE80211_RADIOTAP_RATE] = 0x11,
		[IEEE80211_RADIOTAP_CHANNEL] = 0x24,
		[IEEE80211_RADIOTAP_FHSS] = 0x22,
		[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 0x11,
		[IEEE80211_RADIOTAP_DBM_ANTNOISE] = 0x11,
		[IEEE80211_RADIOTAP_LOCK_QUALITY] = 0x22,
		[IEEE80211_RADIOTAP_TX_ATTENUATION] = 0x22,
		[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 0x22,
		[IEEE80211_RADIOTAP_DBM_TX_POWER] = 0x11,
		[IEEE80211_RADIOTAP_ANTENNA] = 0x11,
		[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 0x11,
		[IEEE80211_RADIOTAP_DB_ANTNOISE] = 0x11,
		[IEEE80211_RADIOTAP_RX_FLAGS] = 0x22,
		[IEEE80211_RADIOTAP_TX_FLAGS] = 0x22,
		[IEEE80211_RADIOTAP_RTS_RETRIES] = 0x11,
		[IEEE80211_RADIOTAP_DATA_RETRIES] = 0x11,
		/*
		 * add more here as they are defined in
		 * include/net/ieee80211_radiotap.h
		 */
	};

	/*
	 * for every radiotap entry we can at
	 * least skip (by knowing the length)...
	 */

	while (iterator->arg_index < sizeof(rt_sizes)) {
	while (1) {
		int hit = 0;
		int pad;
		int pad, align, size, subns, vnslen;
		uint32_t oui;

		/* if no more EXT bits, that's it */
		if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT &&
		    !(iterator->_bitmap_shifter & 1))
			return -ENOENT;

		if (!(iterator->bitmap_shifter & 1))
		if (!(iterator->_bitmap_shifter & 1))
			goto next_entry; /* arg not present */

		/* get alignment/size of data */
		switch (iterator->_arg_index % 32) {
		case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
		case IEEE80211_RADIOTAP_EXT:
			align = 1;
			size = 0;
			break;
		case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
			align = 2;
			size = 6;
			break;
		default:
			if (!iterator->current_namespace ||
			    iterator->_arg_index >= iterator->current_namespace->n_bits) {
				if (iterator->current_namespace == &radiotap_ns)
					return -ENOENT;
				align = 0;
			} else {
				align = iterator->current_namespace->align_size[iterator->_arg_index].align;
				size = iterator->current_namespace->align_size[iterator->_arg_index].size;
			}
			if (!align) {
				/* skip all subsequent data */
				iterator->_arg = iterator->_next_ns_data;
				/* give up on this namespace */
				iterator->current_namespace = NULL;
				goto next_entry;
			}
			break;
		}

		/*
		 * arg is present, account for alignment padding
		 *  8-bit args can be at any alignment
		 * 16-bit args must start on 16-bit boundary
		 * 32-bit args must start on 32-bit boundary
		 * 64-bit args must start on 64-bit boundary
		 *
		 * note that total arg size can differ from alignment of
		 * elements inside arg, so we use upper nybble of length
		 * table to base alignment on
		 *
		 * also note: these alignments are ** relative to the
		 * start of the radiotap header **.  There is no guarantee
		 * Note that these alignments are relative to the start
		 * of the radiotap header.  There is no guarantee
		 * that the radiotap header itself is aligned on any
		 * kind of boundary.
		 *
		 * the above is why get_unaligned() is used to dereference
		 * multibyte elements from the radiotap area
		 * The above is why get_unaligned() is used to dereference
		 * multibyte elements from the radiotap area.
		 */

		pad = (((ulong)iterator->arg) -
			((ulong)iterator->rtheader)) &
			((rt_sizes[iterator->arg_index] >> 4) - 1);
		pad = ((unsigned long)iterator->_arg -
		       (unsigned long)iterator->_rtheader) & (align - 1);

		if (pad)
			iterator->arg +=
				(rt_sizes[iterator->arg_index] >> 4) - pad;
			iterator->_arg += align - pad;

		/*
		 * this is what we will return to user, but we need to
		 * move on first so next call has something fresh to test
		 */
		iterator->this_arg_index = iterator->arg_index;
		iterator->this_arg = iterator->arg;
		hit = 1;
		iterator->this_arg_index = iterator->_arg_index;
		iterator->this_arg = iterator->_arg;
		iterator->this_arg_size = size;

		/* internally move on the size of this arg */
		iterator->arg += rt_sizes[iterator->arg_index] & 0x0f;
		iterator->_arg += size;

		/*
		 * check for insanity where we are given a bitmap that
@@ -228,32 +278,73 @@ int ieee80211_radiotap_iterator_next(
		 * max_length on the last arg, never exceeding it.
		 */

		if (((ulong)iterator->arg - (ulong)iterator->rtheader) >
		    iterator->max_length)
		if ((unsigned long)iterator->_arg -
		    (unsigned long)iterator->_rtheader >
		    (unsigned long)iterator->_max_length)
			return -EINVAL;

		/* these special ones are valid in each bitmap word */
		switch (iterator->_arg_index % 32) {
		case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
			iterator->_bitmap_shifter >>= 1;
			iterator->_arg_index++;

			iterator->_reset_on_ext = 1;

			vnslen = get_unaligned_le16(iterator->this_arg + 4);
			iterator->_next_ns_data = iterator->_arg + vnslen;
			oui = (*iterator->this_arg << 16) |
				(*(iterator->this_arg + 1) << 8) |
				*(iterator->this_arg + 2);
			subns = *(iterator->this_arg + 3);

			find_ns(iterator, oui, subns);

			iterator->is_radiotap_ns = 0;
			/* allow parsers to show this information */
			iterator->this_arg_index =
				IEEE80211_RADIOTAP_VENDOR_NAMESPACE;
			iterator->this_arg_size += vnslen;
			if ((unsigned long)iterator->this_arg +
			    iterator->this_arg_size -
			    (unsigned long)iterator->_rtheader >
			    (unsigned long)(unsigned long)iterator->_max_length)
				return -EINVAL;
			hit = 1;
			break;
		case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
			iterator->_bitmap_shifter >>= 1;
			iterator->_arg_index++;

			iterator->_reset_on_ext = 1;
			iterator->current_namespace = &radiotap_ns;
			iterator->is_radiotap_ns = 1;
			break;
		case IEEE80211_RADIOTAP_EXT:
			/*
			 * bit 31 was set, there is more
			 * -- move to next u32 bitmap
			 */
			iterator->_bitmap_shifter =
				get_unaligned_le32(iterator->_next_bitmap);
			iterator->_next_bitmap++;
			if (iterator->_reset_on_ext)
				iterator->_arg_index = 0;
			else
				iterator->_arg_index++;
			iterator->_reset_on_ext = 0;
			break;
		default:
			/* we've got a hit! */
			hit = 1;
 next_entry:
		iterator->arg_index++;
		if (unlikely((iterator->arg_index & 31) == 0)) {
			/* completed current u32 bitmap */
			if (iterator->bitmap_shifter & 1) {
				/* b31 was set, there is more */
				/* move to next u32 bitmap */
				iterator->bitmap_shifter =
				    get_unaligned_le32(iterator->next_bitmap);
				iterator->next_bitmap++;
			} else
				/* no more bitmaps: end */
				iterator->arg_index = sizeof(rt_sizes);
		} else /* just try the next bit */
			iterator->bitmap_shifter >>= 1;
			iterator->_bitmap_shifter >>= 1;
			iterator->_arg_index++;
		}

		/* if we found a valid arg earlier, return it now */
		if (hit)
			return 0;
	}

	/* we don't know how to handle any more args, we're done */
	return -ENOENT;
}
EXPORT_SYMBOL(ieee80211_radiotap_iterator_next);