Branch data Line data Source code
1 : : /*
2 : : * Radiotap parser
3 : : *
4 : : * Copyright 2007 Andy Green <andy@warmcat.com>
5 : : * Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
6 : : *
7 : : * This program is free software; you can redistribute it and/or modify
8 : : * it under the terms of the GNU General Public License version 2 as
9 : : * published by the Free Software Foundation.
10 : : *
11 : : * Alternatively, this software may be distributed under the terms of BSD
12 : : * license.
13 : : *
14 : : * See COPYING for more details.
15 : : */
16 : :
17 : : #include <linux/kernel.h>
18 : : #include <linux/export.h>
19 : : #include <net/cfg80211.h>
20 : : #include <net/ieee80211_radiotap.h>
21 : : #include <asm/unaligned.h>
22 : :
23 : : /* function prototypes and related defs are in include/net/cfg80211.h */
24 : :
25 : : static const struct radiotap_align_size rtap_namespace_sizes[] = {
26 : : [IEEE80211_RADIOTAP_TSFT] = { .align = 8, .size = 8, },
27 : : [IEEE80211_RADIOTAP_FLAGS] = { .align = 1, .size = 1, },
28 : : [IEEE80211_RADIOTAP_RATE] = { .align = 1, .size = 1, },
29 : : [IEEE80211_RADIOTAP_CHANNEL] = { .align = 2, .size = 4, },
30 : : [IEEE80211_RADIOTAP_FHSS] = { .align = 2, .size = 2, },
31 : : [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = { .align = 1, .size = 1, },
32 : : [IEEE80211_RADIOTAP_DBM_ANTNOISE] = { .align = 1, .size = 1, },
33 : : [IEEE80211_RADIOTAP_LOCK_QUALITY] = { .align = 2, .size = 2, },
34 : : [IEEE80211_RADIOTAP_TX_ATTENUATION] = { .align = 2, .size = 2, },
35 : : [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = { .align = 2, .size = 2, },
36 : : [IEEE80211_RADIOTAP_DBM_TX_POWER] = { .align = 1, .size = 1, },
37 : : [IEEE80211_RADIOTAP_ANTENNA] = { .align = 1, .size = 1, },
38 : : [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = { .align = 1, .size = 1, },
39 : : [IEEE80211_RADIOTAP_DB_ANTNOISE] = { .align = 1, .size = 1, },
40 : : [IEEE80211_RADIOTAP_RX_FLAGS] = { .align = 2, .size = 2, },
41 : : [IEEE80211_RADIOTAP_TX_FLAGS] = { .align = 2, .size = 2, },
42 : : [IEEE80211_RADIOTAP_RTS_RETRIES] = { .align = 1, .size = 1, },
43 : : [IEEE80211_RADIOTAP_DATA_RETRIES] = { .align = 1, .size = 1, },
44 : : [IEEE80211_RADIOTAP_MCS] = { .align = 1, .size = 3, },
45 : : [IEEE80211_RADIOTAP_AMPDU_STATUS] = { .align = 4, .size = 8, },
46 : : [IEEE80211_RADIOTAP_VHT] = { .align = 2, .size = 12, },
47 : : /*
48 : : * add more here as they are defined in radiotap.h
49 : : */
50 : : };
51 : :
52 : : static const struct ieee80211_radiotap_namespace radiotap_ns = {
53 : : .n_bits = ARRAY_SIZE(rtap_namespace_sizes),
54 : : .align_size = rtap_namespace_sizes,
55 : : };
56 : :
57 : : /**
58 : : * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
59 : : * @iterator: radiotap_iterator to initialize
60 : : * @radiotap_header: radiotap header to parse
61 : : * @max_length: total length we can parse into (eg, whole packet length)
62 : : *
63 : : * Returns: 0 or a negative error code if there is a problem.
64 : : *
65 : : * This function initializes an opaque iterator struct which can then
66 : : * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
67 : : * argument which is present in the header. It knows about extended
68 : : * present headers and handles them.
69 : : *
70 : : * How to use:
71 : : * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
72 : : * struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
73 : : * checking for a good 0 return code. Then loop calling
74 : : * __ieee80211_radiotap_iterator_next()... it returns either 0,
75 : : * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
76 : : * The iterator's @this_arg member points to the start of the argument
77 : : * associated with the current argument index that is present, which can be
78 : : * found in the iterator's @this_arg_index member. This arg index corresponds
79 : : * to the IEEE80211_RADIOTAP_... defines.
80 : : *
81 : : * Radiotap header length:
82 : : * You can find the CPU-endian total radiotap header length in
83 : : * iterator->max_length after executing ieee80211_radiotap_iterator_init()
84 : : * successfully.
85 : : *
86 : : * Alignment Gotcha:
87 : : * You must take care when dereferencing iterator.this_arg
88 : : * for multibyte types... the pointer is not aligned. Use
89 : : * get_unaligned((type *)iterator.this_arg) to dereference
90 : : * iterator.this_arg for type "type" safely on all arches.
91 : : *
92 : : * Example code:
93 : : * See Documentation/networking/radiotap-headers.txt
94 : : */
95 : :
96 : 0 : int ieee80211_radiotap_iterator_init(
97 : : struct ieee80211_radiotap_iterator *iterator,
98 : : struct ieee80211_radiotap_header *radiotap_header,
99 : : int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns)
100 : : {
101 : : /* check the radiotap header can actually be present */
102 [ # # ]: 0 : if (max_length < sizeof(struct ieee80211_radiotap_header))
103 : : return -EINVAL;
104 : :
105 : : /* Linux only supports version 0 radiotap format */
106 [ # # ]: 0 : if (radiotap_header->it_version)
107 : : return -EINVAL;
108 : :
109 : : /* sanity check for allowed length and radiotap length field */
110 [ # # ]: 0 : if (max_length < get_unaligned_le16(&radiotap_header->it_len))
111 : : return -EINVAL;
112 : :
113 : 0 : iterator->_rtheader = radiotap_header;
114 [ # # ]: 0 : iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len);
115 : 0 : iterator->_arg_index = 0;
116 [ # # ]: 0 : iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
117 : 0 : iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header);
118 : 0 : iterator->_reset_on_ext = 0;
119 : 0 : iterator->_next_bitmap = &radiotap_header->it_present;
120 : 0 : iterator->_next_bitmap++;
121 : 0 : iterator->_vns = vns;
122 : 0 : iterator->current_namespace = &radiotap_ns;
123 : 0 : iterator->is_radiotap_ns = 1;
124 : :
125 : : /* find payload start allowing for extended bitmap(s) */
126 : :
127 [ # # ]: 0 : if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
128 : 0 : if ((unsigned long)iterator->_arg -
129 : 0 : (unsigned long)iterator->_rtheader + sizeof(uint32_t) >
130 [ # # ]: 0 : (unsigned long)iterator->_max_length)
131 : : return -EINVAL;
132 [ # # ]: 0 : while (get_unaligned_le32(iterator->_arg) &
133 : : (1 << IEEE80211_RADIOTAP_EXT)) {
134 : 0 : iterator->_arg += sizeof(uint32_t);
135 : :
136 : : /*
137 : : * check for insanity where the present bitmaps
138 : : * keep claiming to extend up to or even beyond the
139 : : * stated radiotap header length
140 : : */
141 : :
142 : 0 : if ((unsigned long)iterator->_arg -
143 [ # # ]: 0 : (unsigned long)iterator->_rtheader +
144 : : sizeof(uint32_t) >
145 : : (unsigned long)iterator->_max_length)
146 : : return -EINVAL;
147 : : }
148 : :
149 : 0 : iterator->_arg += sizeof(uint32_t);
150 : :
151 : : /*
152 : : * no need to check again for blowing past stated radiotap
153 : : * header length, because ieee80211_radiotap_iterator_next
154 : : * checks it before it is dereferenced
155 : : */
156 : : }
157 : :
158 : 0 : iterator->this_arg = iterator->_arg;
159 : :
160 : : /* we are all initialized happily */
161 : :
162 : 0 : return 0;
163 : : }
164 : : EXPORT_SYMBOL(ieee80211_radiotap_iterator_init);
165 : :
166 : 0 : static void find_ns(struct ieee80211_radiotap_iterator *iterator,
167 : : uint32_t oui, uint8_t subns)
168 : : {
169 : 0 : int i;
170 : :
171 : 0 : iterator->current_namespace = NULL;
172 : :
173 : 0 : if (!iterator->_vns)
174 : : return;
175 : :
176 [ # # ]: 0 : for (i = 0; i < iterator->_vns->n_ns; i++) {
177 [ # # ]: 0 : if (iterator->_vns->ns[i].oui != oui)
178 : 0 : continue;
179 [ # # ]: 0 : if (iterator->_vns->ns[i].subns != subns)
180 : 0 : continue;
181 : :
182 : 0 : iterator->current_namespace = &iterator->_vns->ns[i];
183 : 0 : break;
184 : : }
185 : : }
186 : :
187 : :
188 : :
189 : : /**
190 : : * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
191 : : * @iterator: radiotap_iterator to move to next arg (if any)
192 : : *
193 : : * Returns: 0 if there is an argument to handle,
194 : : * -ENOENT if there are no more args or -EINVAL
195 : : * if there is something else wrong.
196 : : *
197 : : * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*)
198 : : * in @this_arg_index and sets @this_arg to point to the
199 : : * payload for the field. It takes care of alignment handling and extended
200 : : * present fields. @this_arg can be changed by the caller (eg,
201 : : * incremented to move inside a compound argument like
202 : : * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in
203 : : * little-endian format whatever the endianess of your CPU.
204 : : *
205 : : * Alignment Gotcha:
206 : : * You must take care when dereferencing iterator.this_arg
207 : : * for multibyte types... the pointer is not aligned. Use
208 : : * get_unaligned((type *)iterator.this_arg) to dereference
209 : : * iterator.this_arg for type "type" safely on all arches.
210 : : */
211 : :
212 : 0 : int ieee80211_radiotap_iterator_next(
213 : : struct ieee80211_radiotap_iterator *iterator)
214 : : {
215 : 0 : while (1) {
216 : 0 : int hit = 0;
217 : 0 : int pad, align, size, subns;
218 : 0 : uint32_t oui;
219 : :
220 : : /* if no more EXT bits, that's it */
221 [ # # ]: 0 : if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT &&
222 [ # # ]: 0 : !(iterator->_bitmap_shifter & 1))
223 : : return -ENOENT;
224 : :
225 [ # # ]: 0 : if (!(iterator->_bitmap_shifter & 1))
226 : 0 : goto next_entry; /* arg not present */
227 : :
228 : : /* get alignment/size of data */
229 [ # # # ]: 0 : switch (iterator->_arg_index % 32) {
230 : : case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
231 : : case IEEE80211_RADIOTAP_EXT:
232 : : align = 1;
233 : : size = 0;
234 : : break;
235 : 0 : case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
236 : 0 : align = 2;
237 : 0 : size = 6;
238 : 0 : break;
239 : 0 : default:
240 [ # # ]: 0 : if (!iterator->current_namespace ||
241 [ # # ]: 0 : iterator->_arg_index >= iterator->current_namespace->n_bits) {
242 [ # # ]: 0 : if (iterator->current_namespace == &radiotap_ns)
243 : : return -ENOENT;
244 : : align = 0;
245 : : } else {
246 : 0 : align = iterator->current_namespace->align_size[iterator->_arg_index].align;
247 : 0 : size = iterator->current_namespace->align_size[iterator->_arg_index].size;
248 : : }
249 [ # # ]: 0 : if (!align) {
250 : : /* skip all subsequent data */
251 : 0 : iterator->_arg = iterator->_next_ns_data;
252 : : /* give up on this namespace */
253 : 0 : iterator->current_namespace = NULL;
254 : 0 : goto next_entry;
255 : : }
256 : : break;
257 : : }
258 : :
259 : : /*
260 : : * arg is present, account for alignment padding
261 : : *
262 : : * Note that these alignments are relative to the start
263 : : * of the radiotap header. There is no guarantee
264 : : * that the radiotap header itself is aligned on any
265 : : * kind of boundary.
266 : : *
267 : : * The above is why get_unaligned() is used to dereference
268 : : * multibyte elements from the radiotap area.
269 : : */
270 : :
271 : 0 : pad = ((unsigned long)iterator->_arg -
272 : 0 : (unsigned long)iterator->_rtheader) & (align - 1);
273 : :
274 [ # # ]: 0 : if (pad)
275 : 0 : iterator->_arg += align - pad;
276 : :
277 [ # # ]: 0 : if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) {
278 : 0 : int vnslen;
279 : :
280 : 0 : if ((unsigned long)iterator->_arg + size -
281 : : (unsigned long)iterator->_rtheader >
282 [ # # ]: 0 : (unsigned long)iterator->_max_length)
283 : : return -EINVAL;
284 : :
285 : 0 : oui = (*iterator->_arg << 16) |
286 : 0 : (*(iterator->_arg + 1) << 8) |
287 : 0 : *(iterator->_arg + 2);
288 : 0 : subns = *(iterator->_arg + 3);
289 : :
290 [ # # ]: 0 : find_ns(iterator, oui, subns);
291 : :
292 [ # # ]: 0 : vnslen = get_unaligned_le16(iterator->_arg + 4);
293 : 0 : iterator->_next_ns_data = iterator->_arg + size + vnslen;
294 [ # # ]: 0 : if (!iterator->current_namespace)
295 : 0 : size += vnslen;
296 : : }
297 : :
298 : : /*
299 : : * this is what we will return to user, but we need to
300 : : * move on first so next call has something fresh to test
301 : : */
302 : 0 : iterator->this_arg_index = iterator->_arg_index;
303 : 0 : iterator->this_arg = iterator->_arg;
304 : 0 : iterator->this_arg_size = size;
305 : :
306 : : /* internally move on the size of this arg */
307 : 0 : iterator->_arg += size;
308 : :
309 : : /*
310 : : * check for insanity where we are given a bitmap that
311 : : * claims to have more arg content than the length of the
312 : : * radiotap section. We will normally end up equalling this
313 : : * max_length on the last arg, never exceeding it.
314 : : */
315 : :
316 : 0 : if ((unsigned long)iterator->_arg -
317 : : (unsigned long)iterator->_rtheader >
318 [ # # ]: 0 : (unsigned long)iterator->_max_length)
319 : : return -EINVAL;
320 : :
321 : : /* these special ones are valid in each bitmap word */
322 [ # # # # ]: 0 : switch (iterator->_arg_index % 32) {
323 : 0 : case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
324 : 0 : iterator->_reset_on_ext = 1;
325 : :
326 : 0 : iterator->is_radiotap_ns = 0;
327 : : /*
328 : : * If parser didn't register this vendor
329 : : * namespace with us, allow it to show it
330 : : * as 'raw. Do do that, set argument index
331 : : * to vendor namespace.
332 : : */
333 : 0 : iterator->this_arg_index =
334 : : IEEE80211_RADIOTAP_VENDOR_NAMESPACE;
335 [ # # ]: 0 : if (!iterator->current_namespace)
336 : 0 : hit = 1;
337 : 0 : goto next_entry;
338 : 0 : case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
339 : 0 : iterator->_reset_on_ext = 1;
340 : 0 : iterator->current_namespace = &radiotap_ns;
341 : 0 : iterator->is_radiotap_ns = 1;
342 : 0 : goto next_entry;
343 : 0 : case IEEE80211_RADIOTAP_EXT:
344 : : /*
345 : : * bit 31 was set, there is more
346 : : * -- move to next u32 bitmap
347 : : */
348 : 0 : iterator->_bitmap_shifter =
349 [ # # ]: 0 : get_unaligned_le32(iterator->_next_bitmap);
350 : 0 : iterator->_next_bitmap++;
351 [ # # ]: 0 : if (iterator->_reset_on_ext)
352 : 0 : iterator->_arg_index = 0;
353 : : else
354 : 0 : iterator->_arg_index++;
355 : 0 : iterator->_reset_on_ext = 0;
356 : 0 : break;
357 : : default:
358 : : /* we've got a hit! */
359 : : hit = 1;
360 : 0 : next_entry:
361 : 0 : iterator->_bitmap_shifter >>= 1;
362 : 0 : iterator->_arg_index++;
363 : : }
364 : :
365 : : /* if we found a valid arg earlier, return it now */
366 [ # # ]: 0 : if (hit)
367 : : return 0;
368 : : }
369 : : }
370 : : EXPORT_SYMBOL(ieee80211_radiotap_iterator_next);
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