diff options
Diffstat (limited to 'net/wireless/radiotap.c')
| -rw-r--r-- | net/wireless/radiotap.c | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/net/wireless/radiotap.c b/net/wireless/radiotap.c new file mode 100644 index 000000000..ae2e1a896 --- /dev/null +++ b/net/wireless/radiotap.c @@ -0,0 +1,370 @@ +/* + * 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) + * @vns: vendor namespaces to parse + * + * 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.rst + */ + +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->it_optional; + iterator->_reset_on_ext = 0; + iterator->_next_bitmap = radiotap_header->it_optional; + 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 & (BIT(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) & + (BIT(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; +} +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 + * @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; + } +} +EXPORT_SYMBOL(ieee80211_radiotap_iterator_next); |