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Release 4.14 net/wireless/radiotap.c

Directory: net/wireless
/*
 * 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 <linux/kernel.h>
#include <linux/export.h>
#include <net/cfg80211.h>
#include <net/ieee80211_radiotap.h>
#include <asm/unaligned.h>

/* 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, },
	[IEEE80211_RADIOTAP_MCS] = { .align = 1, .size = 3, },
	[IEEE80211_RADIOTAP_AMPDU_STATUS] = { .align = 4, .size = 8, },
	[IEEE80211_RADIOTAP_VHT] = { .align = 2, .size = 12, },
	/*
         * add more here as they are defined in radiotap.h
         */
};


static const struct ieee80211_radiotap_namespace radiotap_ns = {
	.n_bits = ARRAY_SIZE(rtap_namespace_sizes),
	.align_size = rtap_namespace_sizes,
};

/**
 * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
 * @iterator: radiotap_iterator to initialize
 * @radiotap_header: radiotap header to parse
 * @max_length: total length we can parse into (eg, whole packet length)
 *
 * Returns: 0 or a negative error code if there is a problem.
 *
 * This function initializes an opaque iterator struct which can then
 * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
 * argument which is present in the header.  It knows about extended
 * present headers and handles them.
 *
 * How to use:
 * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
 * struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
 * checking for a good 0 return code.  Then loop calling
 * __ieee80211_radiotap_iterator_next()... it returns either 0,
 * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
 * The iterator's @this_arg member points to the start of the argument
 * associated with the current argument index that is present, which can be
 * found in the iterator's @this_arg_index member.  This arg index corresponds
 * to the IEEE80211_RADIOTAP_... defines.
 *
 * Radiotap header length:
 * You can find the CPU-endian total radiotap header length in
 * iterator->max_length after executing ieee80211_radiotap_iterator_init()
 * successfully.
 *
 * Alignment Gotcha:
 * 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.
 *
 * Example code:
 * See Documentation/networking/radiotap-headers.txt
 */


int ieee80211_radiotap_iterator_init( struct ieee80211_radiotap_iterator *iterator, struct ieee80211_radiotap_header *radiotap_header, int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns) { /* check the radiotap header can actually be present */ if (max_length < sizeof(struct ieee80211_radiotap_header)) return -EINVAL; /* Linux only supports version 0 radiotap format */ if (radiotap_header->it_version) return -EINVAL; /* sanity check for allowed length and radiotap length field */ 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 = (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 (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) { if ((unsigned long)iterator->_arg - (unsigned long)iterator->_rtheader + sizeof(uint32_t) > (unsigned long)iterator->_max_length) return -EINVAL; while (get_unaligned_le32(iterator->_arg) & (1 << IEEE80211_RADIOTAP_EXT)) { iterator->_arg += sizeof(uint32_t); /* * check for insanity where the present bitmaps * keep claiming to extend up to or even beyond the * stated radiotap header length */ if ((unsigned long)iterator->_arg - (unsigned long)iterator->_rtheader + sizeof(uint32_t) > (unsigned long)iterator->_max_length) return -EINVAL; } iterator->_arg += sizeof(uint32_t); /* * no need to check again for blowing past stated radiotap * header length, because ieee80211_radiotap_iterator_next * checks it before it is dereferenced */ } iterator->this_arg = iterator->_arg; /* we are all initialized happily */ return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Andy Green15753.77%120.00%
Johannes Berg13144.86%360.00%
Harvey Harrison41.37%120.00%
Total292100.00%5100.00%

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; } }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Berg9191.00%266.67%
Andy Green99.00%133.33%
Total100100.00%3100.00%

/** * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg * @iterator: radiotap_iterator to move to next arg (if any) * * Returns: 0 if there is an argument to handle, * -ENOENT if there are no more args or -EINVAL * if there is something else wrong. * * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*) * in @this_arg_index and sets @this_arg to point to the * payload for the field. It takes care of alignment handling and extended * present fields. @this_arg can be changed by the caller (eg, * incremented to move inside a compound argument like * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in * little-endian format whatever the endianess of your CPU. * * Alignment Gotcha: * 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. */
int ieee80211_radiotap_iterator_next( struct ieee80211_radiotap_iterator *iterator) { while (1) { int hit = 0; int pad, align, size, subns; 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)) 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 * * 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. */ pad = ((unsigned long)iterator->_arg - (unsigned long)iterator->_rtheader) & (align - 1); if (pad) iterator->_arg += align - pad; if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) { int vnslen; if ((unsigned long)iterator->_arg + size - (unsigned long)iterator->_rtheader > (unsigned long)iterator->_max_length) return -EINVAL; oui = (*iterator->_arg << 16) | (*(iterator->_arg + 1) << 8) | *(iterator->_arg + 2); subns = *(iterator->_arg + 3); find_ns(iterator, oui, subns); vnslen = get_unaligned_le16(iterator->_arg + 4); iterator->_next_ns_data = iterator->_arg + size + vnslen; if (!iterator->current_namespace) size += vnslen; } /* * 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; iterator->this_arg_size = size; /* internally move on the size of this arg */ iterator->_arg += size; /* * check for insanity where we are given a bitmap that * claims to have more arg content than the length of the * radiotap section. We will normally end up equalling this * max_length on the last arg, never exceeding it. */ 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->_reset_on_ext = 1; iterator->is_radiotap_ns = 0; /* * If parser didn't register this vendor * namespace with us, allow it to show it * as 'raw. Do do that, set argument index * to vendor namespace. */ iterator->this_arg_index = IEEE80211_RADIOTAP_VENDOR_NAMESPACE; if (!iterator->current_namespace) hit = 1; goto next_entry; case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: iterator->_reset_on_ext = 1; iterator->current_namespace = &radiotap_ns; iterator->is_radiotap_ns = 1; goto next_entry; 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->_bitmap_shifter >>= 1; iterator->_arg_index++; } /* if we found a valid arg earlier, return it now */ if (hit) return 0; } }

Contributors

PersonTokensPropCommitsCommitProp
Johannes Berg46779.56%250.00%
Andy Green11920.27%125.00%
Harvey Harrison10.17%125.00%
Total587100.00%4100.00%

EXPORT_SYMBOL(ieee80211_radiotap_iterator_next);

Overall Contributors

PersonTokensPropCommitsCommitProp
Johannes Berg104275.73%654.55%
Andy Green30622.24%19.09%
Lorenzo Bianconi161.16%19.09%
Harvey Harrison50.36%19.09%
Nikitas Angelinas40.29%19.09%
Paul Gortmaker30.22%19.09%
Total1376100.00%11100.00%
Directory: net/wireless
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