1214501Srpaulo/* 2214501Srpaulo * Radiotap parser 3214501Srpaulo * 4214501Srpaulo * Copyright 2007 Andy Green <andy@warmcat.com> 5281806Srpaulo * Copyright 2009 Johannes Berg <johannes@sipsolutions.net> 6214501Srpaulo * 7214501Srpaulo * This program is free software; you can redistribute it and/or modify 8214501Srpaulo * it under the terms of the GNU General Public License version 2 as 9214501Srpaulo * published by the Free Software Foundation. 10214501Srpaulo * 11214501Srpaulo * Alternatively, this software may be distributed under the terms of BSD 12214501Srpaulo * license. 13214501Srpaulo * 14281806Srpaulo * See COPYING for more details. 15214501Srpaulo */ 16337817Scy#include "platform.h" 17281806Srpaulo#include "radiotap_iter.h" 18214501Srpaulo 19281806Srpaulo/* function prototypes and related defs are in radiotap_iter.h */ 20214501Srpaulo 21281806Srpaulostatic const struct radiotap_align_size rtap_namespace_sizes[] = { 22281806Srpaulo [IEEE80211_RADIOTAP_TSFT] = { .align = 8, .size = 8, }, 23281806Srpaulo [IEEE80211_RADIOTAP_FLAGS] = { .align = 1, .size = 1, }, 24281806Srpaulo [IEEE80211_RADIOTAP_RATE] = { .align = 1, .size = 1, }, 25281806Srpaulo [IEEE80211_RADIOTAP_CHANNEL] = { .align = 2, .size = 4, }, 26281806Srpaulo [IEEE80211_RADIOTAP_FHSS] = { .align = 2, .size = 2, }, 27281806Srpaulo [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = { .align = 1, .size = 1, }, 28281806Srpaulo [IEEE80211_RADIOTAP_DBM_ANTNOISE] = { .align = 1, .size = 1, }, 29281806Srpaulo [IEEE80211_RADIOTAP_LOCK_QUALITY] = { .align = 2, .size = 2, }, 30281806Srpaulo [IEEE80211_RADIOTAP_TX_ATTENUATION] = { .align = 2, .size = 2, }, 31281806Srpaulo [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = { .align = 2, .size = 2, }, 32281806Srpaulo [IEEE80211_RADIOTAP_DBM_TX_POWER] = { .align = 1, .size = 1, }, 33281806Srpaulo [IEEE80211_RADIOTAP_ANTENNA] = { .align = 1, .size = 1, }, 34281806Srpaulo [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = { .align = 1, .size = 1, }, 35281806Srpaulo [IEEE80211_RADIOTAP_DB_ANTNOISE] = { .align = 1, .size = 1, }, 36281806Srpaulo [IEEE80211_RADIOTAP_RX_FLAGS] = { .align = 2, .size = 2, }, 37281806Srpaulo [IEEE80211_RADIOTAP_TX_FLAGS] = { .align = 2, .size = 2, }, 38281806Srpaulo [IEEE80211_RADIOTAP_RTS_RETRIES] = { .align = 1, .size = 1, }, 39281806Srpaulo [IEEE80211_RADIOTAP_DATA_RETRIES] = { .align = 1, .size = 1, }, 40281806Srpaulo [IEEE80211_RADIOTAP_MCS] = { .align = 1, .size = 3, }, 41281806Srpaulo [IEEE80211_RADIOTAP_AMPDU_STATUS] = { .align = 4, .size = 8, }, 42281806Srpaulo /* 43281806Srpaulo * add more here as they are defined in radiotap.h 44281806Srpaulo */ 45281806Srpaulo}; 46214501Srpaulo 47281806Srpaulostatic const struct ieee80211_radiotap_namespace radiotap_ns = { 48281806Srpaulo .n_bits = sizeof(rtap_namespace_sizes) / sizeof(rtap_namespace_sizes[0]), 49281806Srpaulo .align_size = rtap_namespace_sizes, 50281806Srpaulo}; 51214501Srpaulo 52214501Srpaulo/** 53214501Srpaulo * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization 54214501Srpaulo * @iterator: radiotap_iterator to initialize 55214501Srpaulo * @radiotap_header: radiotap header to parse 56214501Srpaulo * @max_length: total length we can parse into (eg, whole packet length) 57214501Srpaulo * 58214501Srpaulo * Returns: 0 or a negative error code if there is a problem. 59214501Srpaulo * 60214501Srpaulo * This function initializes an opaque iterator struct which can then 61214501Srpaulo * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap 62214501Srpaulo * argument which is present in the header. It knows about extended 63214501Srpaulo * present headers and handles them. 64214501Srpaulo * 65214501Srpaulo * How to use: 66214501Srpaulo * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator 67214501Srpaulo * struct ieee80211_radiotap_iterator (no need to init the struct beforehand) 68214501Srpaulo * checking for a good 0 return code. Then loop calling 69214501Srpaulo * __ieee80211_radiotap_iterator_next()... it returns either 0, 70214501Srpaulo * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem. 71214501Srpaulo * The iterator's @this_arg member points to the start of the argument 72214501Srpaulo * associated with the current argument index that is present, which can be 73214501Srpaulo * found in the iterator's @this_arg_index member. This arg index corresponds 74214501Srpaulo * to the IEEE80211_RADIOTAP_... defines. 75214501Srpaulo * 76214501Srpaulo * Radiotap header length: 77214501Srpaulo * You can find the CPU-endian total radiotap header length in 78214501Srpaulo * iterator->max_length after executing ieee80211_radiotap_iterator_init() 79214501Srpaulo * successfully. 80214501Srpaulo * 81214501Srpaulo * Alignment Gotcha: 82214501Srpaulo * You must take care when dereferencing iterator.this_arg 83214501Srpaulo * for multibyte types... the pointer is not aligned. Use 84214501Srpaulo * get_unaligned((type *)iterator.this_arg) to dereference 85214501Srpaulo * iterator.this_arg for type "type" safely on all arches. 86214501Srpaulo * 87281806Srpaulo * Example code: parse.c 88214501Srpaulo */ 89214501Srpaulo 90214501Srpauloint ieee80211_radiotap_iterator_init( 91281806Srpaulo struct ieee80211_radiotap_iterator *iterator, 92281806Srpaulo struct ieee80211_radiotap_header *radiotap_header, 93281806Srpaulo int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns) 94214501Srpaulo{ 95281806Srpaulo /* must at least have the radiotap header */ 96281806Srpaulo if (max_length < (int)sizeof(struct ieee80211_radiotap_header)) 97281806Srpaulo return -EINVAL; 98281806Srpaulo 99214501Srpaulo /* Linux only supports version 0 radiotap format */ 100214501Srpaulo if (radiotap_header->it_version) 101214501Srpaulo return -EINVAL; 102214501Srpaulo 103214501Srpaulo /* sanity check for allowed length and radiotap length field */ 104281806Srpaulo if (max_length < get_unaligned_le16(&radiotap_header->it_len)) 105214501Srpaulo return -EINVAL; 106214501Srpaulo 107281806Srpaulo iterator->_rtheader = radiotap_header; 108281806Srpaulo iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len); 109281806Srpaulo iterator->_arg_index = 0; 110281806Srpaulo iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present); 111281806Srpaulo iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header); 112281806Srpaulo iterator->_next_ns_data = NULL; 113281806Srpaulo iterator->_reset_on_ext = 0; 114281806Srpaulo iterator->_next_bitmap = &radiotap_header->it_present; 115281806Srpaulo iterator->_next_bitmap++; 116281806Srpaulo iterator->_vns = vns; 117281806Srpaulo iterator->current_namespace = &radiotap_ns; 118281806Srpaulo iterator->is_radiotap_ns = 1; 119281806Srpaulo#ifdef RADIOTAP_SUPPORT_OVERRIDES 120281806Srpaulo iterator->n_overrides = 0; 121281806Srpaulo iterator->overrides = NULL; 122281806Srpaulo#endif 123214501Srpaulo 124214501Srpaulo /* find payload start allowing for extended bitmap(s) */ 125214501Srpaulo 126289549Srpaulo if (iterator->_bitmap_shifter & BIT(IEEE80211_RADIOTAP_EXT)) { 127281806Srpaulo if ((unsigned long)iterator->_arg - 128281806Srpaulo (unsigned long)iterator->_rtheader + sizeof(uint32_t) > 129281806Srpaulo (unsigned long)iterator->_max_length) 130281806Srpaulo return -EINVAL; 131281806Srpaulo while (get_unaligned_le32(iterator->_arg) & 132289549Srpaulo BIT(IEEE80211_RADIOTAP_EXT)) { 133281806Srpaulo iterator->_arg += sizeof(uint32_t); 134214501Srpaulo 135214501Srpaulo /* 136214501Srpaulo * check for insanity where the present bitmaps 137214501Srpaulo * keep claiming to extend up to or even beyond the 138214501Srpaulo * stated radiotap header length 139214501Srpaulo */ 140214501Srpaulo 141281806Srpaulo if ((unsigned long)iterator->_arg - 142281806Srpaulo (unsigned long)iterator->_rtheader + 143281806Srpaulo sizeof(uint32_t) > 144281806Srpaulo (unsigned long)iterator->_max_length) 145214501Srpaulo return -EINVAL; 146214501Srpaulo } 147214501Srpaulo 148281806Srpaulo iterator->_arg += sizeof(uint32_t); 149214501Srpaulo 150214501Srpaulo /* 151214501Srpaulo * no need to check again for blowing past stated radiotap 152214501Srpaulo * header length, because ieee80211_radiotap_iterator_next 153214501Srpaulo * checks it before it is dereferenced 154214501Srpaulo */ 155214501Srpaulo } 156214501Srpaulo 157281806Srpaulo iterator->this_arg = iterator->_arg; 158281806Srpaulo iterator->this_arg_index = 0; 159281806Srpaulo iterator->this_arg_size = 0; 160281806Srpaulo 161214501Srpaulo /* we are all initialized happily */ 162214501Srpaulo 163214501Srpaulo return 0; 164214501Srpaulo} 165214501Srpaulo 166281806Srpaulostatic void find_ns(struct ieee80211_radiotap_iterator *iterator, 167281806Srpaulo uint32_t oui, uint8_t subns) 168281806Srpaulo{ 169281806Srpaulo int i; 170214501Srpaulo 171281806Srpaulo iterator->current_namespace = NULL; 172281806Srpaulo 173281806Srpaulo if (!iterator->_vns) 174281806Srpaulo return; 175281806Srpaulo 176281806Srpaulo for (i = 0; i < iterator->_vns->n_ns; i++) { 177281806Srpaulo if (iterator->_vns->ns[i].oui != oui) 178281806Srpaulo continue; 179281806Srpaulo if (iterator->_vns->ns[i].subns != subns) 180281806Srpaulo continue; 181281806Srpaulo 182281806Srpaulo iterator->current_namespace = &iterator->_vns->ns[i]; 183281806Srpaulo break; 184281806Srpaulo } 185281806Srpaulo} 186281806Srpaulo 187281806Srpaulo#ifdef RADIOTAP_SUPPORT_OVERRIDES 188281806Srpaulostatic int find_override(struct ieee80211_radiotap_iterator *iterator, 189281806Srpaulo int *align, int *size) 190281806Srpaulo{ 191281806Srpaulo int i; 192281806Srpaulo 193281806Srpaulo if (!iterator->overrides) 194281806Srpaulo return 0; 195281806Srpaulo 196281806Srpaulo for (i = 0; i < iterator->n_overrides; i++) { 197281806Srpaulo if (iterator->_arg_index == iterator->overrides[i].field) { 198281806Srpaulo *align = iterator->overrides[i].align; 199281806Srpaulo *size = iterator->overrides[i].size; 200281806Srpaulo if (!*align) /* erroneous override */ 201281806Srpaulo return 0; 202281806Srpaulo return 1; 203281806Srpaulo } 204281806Srpaulo } 205281806Srpaulo 206281806Srpaulo return 0; 207281806Srpaulo} 208281806Srpaulo#endif 209281806Srpaulo 210281806Srpaulo 211214501Srpaulo/** 212214501Srpaulo * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg 213214501Srpaulo * @iterator: radiotap_iterator to move to next arg (if any) 214214501Srpaulo * 215214501Srpaulo * Returns: 0 if there is an argument to handle, 216214501Srpaulo * -ENOENT if there are no more args or -EINVAL 217214501Srpaulo * if there is something else wrong. 218214501Srpaulo * 219214501Srpaulo * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*) 220214501Srpaulo * in @this_arg_index and sets @this_arg to point to the 221214501Srpaulo * payload for the field. It takes care of alignment handling and extended 222214501Srpaulo * present fields. @this_arg can be changed by the caller (eg, 223214501Srpaulo * incremented to move inside a compound argument like 224214501Srpaulo * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in 225214501Srpaulo * little-endian format whatever the endianess of your CPU. 226214501Srpaulo * 227214501Srpaulo * Alignment Gotcha: 228214501Srpaulo * You must take care when dereferencing iterator.this_arg 229214501Srpaulo * for multibyte types... the pointer is not aligned. Use 230214501Srpaulo * get_unaligned((type *)iterator.this_arg) to dereference 231214501Srpaulo * iterator.this_arg for type "type" safely on all arches. 232214501Srpaulo */ 233214501Srpaulo 234214501Srpauloint ieee80211_radiotap_iterator_next( 235281806Srpaulo struct ieee80211_radiotap_iterator *iterator) 236214501Srpaulo{ 237281806Srpaulo while (1) { 238281806Srpaulo int hit = 0; 239281806Srpaulo int pad, align, size, subns; 240281806Srpaulo uint32_t oui; 241214501Srpaulo 242281806Srpaulo /* if no more EXT bits, that's it */ 243281806Srpaulo if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT && 244281806Srpaulo !(iterator->_bitmap_shifter & 1)) 245281806Srpaulo return -ENOENT; 246214501Srpaulo 247281806Srpaulo if (!(iterator->_bitmap_shifter & 1)) 248281806Srpaulo goto next_entry; /* arg not present */ 249214501Srpaulo 250281806Srpaulo /* get alignment/size of data */ 251281806Srpaulo switch (iterator->_arg_index % 32) { 252281806Srpaulo case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: 253281806Srpaulo case IEEE80211_RADIOTAP_EXT: 254281806Srpaulo align = 1; 255281806Srpaulo size = 0; 256281806Srpaulo break; 257281806Srpaulo case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: 258281806Srpaulo align = 2; 259281806Srpaulo size = 6; 260281806Srpaulo break; 261281806Srpaulo default: 262281806Srpaulo#ifdef RADIOTAP_SUPPORT_OVERRIDES 263281806Srpaulo if (find_override(iterator, &align, &size)) { 264281806Srpaulo /* all set */ 265281806Srpaulo } else 266281806Srpaulo#endif 267281806Srpaulo if (!iterator->current_namespace || 268281806Srpaulo iterator->_arg_index >= iterator->current_namespace->n_bits) { 269281806Srpaulo if (iterator->current_namespace == &radiotap_ns) 270281806Srpaulo return -ENOENT; 271281806Srpaulo align = 0; 272281806Srpaulo } else { 273281806Srpaulo align = iterator->current_namespace->align_size[iterator->_arg_index].align; 274281806Srpaulo size = iterator->current_namespace->align_size[iterator->_arg_index].size; 275281806Srpaulo } 276281806Srpaulo if (!align) { 277281806Srpaulo /* skip all subsequent data */ 278281806Srpaulo iterator->_arg = iterator->_next_ns_data; 279281806Srpaulo /* give up on this namespace */ 280281806Srpaulo iterator->current_namespace = NULL; 281281806Srpaulo goto next_entry; 282281806Srpaulo } 283281806Srpaulo break; 284281806Srpaulo } 285214501Srpaulo 286214501Srpaulo /* 287214501Srpaulo * arg is present, account for alignment padding 288214501Srpaulo * 289281806Srpaulo * Note that these alignments are relative to the start 290281806Srpaulo * of the radiotap header. There is no guarantee 291214501Srpaulo * that the radiotap header itself is aligned on any 292214501Srpaulo * kind of boundary. 293214501Srpaulo * 294281806Srpaulo * The above is why get_unaligned() is used to dereference 295281806Srpaulo * multibyte elements from the radiotap area. 296214501Srpaulo */ 297214501Srpaulo 298281806Srpaulo pad = ((unsigned long)iterator->_arg - 299281806Srpaulo (unsigned long)iterator->_rtheader) & (align - 1); 300214501Srpaulo 301214501Srpaulo if (pad) 302281806Srpaulo iterator->_arg += align - pad; 303214501Srpaulo 304281806Srpaulo if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) { 305281806Srpaulo int vnslen; 306281806Srpaulo 307281806Srpaulo if ((unsigned long)iterator->_arg + size - 308281806Srpaulo (unsigned long)iterator->_rtheader > 309281806Srpaulo (unsigned long)iterator->_max_length) 310281806Srpaulo return -EINVAL; 311281806Srpaulo 312281806Srpaulo oui = (*iterator->_arg << 16) | 313281806Srpaulo (*(iterator->_arg + 1) << 8) | 314281806Srpaulo *(iterator->_arg + 2); 315281806Srpaulo subns = *(iterator->_arg + 3); 316281806Srpaulo 317281806Srpaulo find_ns(iterator, oui, subns); 318281806Srpaulo 319281806Srpaulo vnslen = get_unaligned_le16(iterator->_arg + 4); 320281806Srpaulo iterator->_next_ns_data = iterator->_arg + size + vnslen; 321281806Srpaulo if (!iterator->current_namespace) 322281806Srpaulo size += vnslen; 323281806Srpaulo } 324281806Srpaulo 325214501Srpaulo /* 326214501Srpaulo * this is what we will return to user, but we need to 327214501Srpaulo * move on first so next call has something fresh to test 328214501Srpaulo */ 329281806Srpaulo iterator->this_arg_index = iterator->_arg_index; 330281806Srpaulo iterator->this_arg = iterator->_arg; 331281806Srpaulo iterator->this_arg_size = size; 332214501Srpaulo 333214501Srpaulo /* internally move on the size of this arg */ 334281806Srpaulo iterator->_arg += size; 335214501Srpaulo 336214501Srpaulo /* 337214501Srpaulo * check for insanity where we are given a bitmap that 338214501Srpaulo * claims to have more arg content than the length of the 339214501Srpaulo * radiotap section. We will normally end up equalling this 340214501Srpaulo * max_length on the last arg, never exceeding it. 341214501Srpaulo */ 342214501Srpaulo 343281806Srpaulo if ((unsigned long)iterator->_arg - 344281806Srpaulo (unsigned long)iterator->_rtheader > 345281806Srpaulo (unsigned long)iterator->_max_length) 346214501Srpaulo return -EINVAL; 347214501Srpaulo 348281806Srpaulo /* these special ones are valid in each bitmap word */ 349281806Srpaulo switch (iterator->_arg_index % 32) { 350281806Srpaulo case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: 351281806Srpaulo iterator->_reset_on_ext = 1; 352214501Srpaulo 353281806Srpaulo iterator->is_radiotap_ns = 0; 354281806Srpaulo /* 355281806Srpaulo * If parser didn't register this vendor 356281806Srpaulo * namespace with us, allow it to show it 357281806Srpaulo * as 'raw. Do do that, set argument index 358281806Srpaulo * to vendor namespace. 359281806Srpaulo */ 360281806Srpaulo iterator->this_arg_index = 361281806Srpaulo IEEE80211_RADIOTAP_VENDOR_NAMESPACE; 362281806Srpaulo if (!iterator->current_namespace) 363281806Srpaulo hit = 1; 364281806Srpaulo goto next_entry; 365281806Srpaulo case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: 366281806Srpaulo iterator->_reset_on_ext = 1; 367281806Srpaulo iterator->current_namespace = &radiotap_ns; 368281806Srpaulo iterator->is_radiotap_ns = 1; 369281806Srpaulo goto next_entry; 370281806Srpaulo case IEEE80211_RADIOTAP_EXT: 371281806Srpaulo /* 372281806Srpaulo * bit 31 was set, there is more 373281806Srpaulo * -- move to next u32 bitmap 374281806Srpaulo */ 375281806Srpaulo iterator->_bitmap_shifter = 376281806Srpaulo get_unaligned_le32(iterator->_next_bitmap); 377281806Srpaulo iterator->_next_bitmap++; 378281806Srpaulo if (iterator->_reset_on_ext) 379281806Srpaulo iterator->_arg_index = 0; 380281806Srpaulo else 381281806Srpaulo iterator->_arg_index++; 382281806Srpaulo iterator->_reset_on_ext = 0; 383281806Srpaulo break; 384281806Srpaulo default: 385281806Srpaulo /* we've got a hit! */ 386281806Srpaulo hit = 1; 387281806Srpaulo next_entry: 388281806Srpaulo iterator->_bitmap_shifter >>= 1; 389281806Srpaulo iterator->_arg_index++; 390281806Srpaulo } 391281806Srpaulo 392214501Srpaulo /* if we found a valid arg earlier, return it now */ 393214501Srpaulo if (hit) 394214501Srpaulo return 0; 395214501Srpaulo } 396214501Srpaulo} 397