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179f831b AG |
1 | /* |
2 | * Radiotap parser | |
3 | * | |
4 | * Copyright 2007 Andy Green <andy@warmcat.com> | |
33e5a2f7 JB |
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. | |
179f831b AG |
15 | */ |
16 | ||
94262316 | 17 | #include <linux/kernel.h> |
bc3b2d7f | 18 | #include <linux/export.h> |
179f831b AG |
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 | ||
33e5a2f7 JB |
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 | /* | |
45 | * add more here as they are defined in radiotap.h | |
46 | */ | |
47 | }; | |
48 | ||
49 | static const struct ieee80211_radiotap_namespace radiotap_ns = { | |
94262316 | 50 | .n_bits = ARRAY_SIZE(rtap_namespace_sizes), |
33e5a2f7 JB |
51 | .align_size = rtap_namespace_sizes, |
52 | }; | |
53 | ||
179f831b AG |
54 | /** |
55 | * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization | |
56 | * @iterator: radiotap_iterator to initialize | |
57 | * @radiotap_header: radiotap header to parse | |
58 | * @max_length: total length we can parse into (eg, whole packet length) | |
59 | * | |
60 | * Returns: 0 or a negative error code if there is a problem. | |
61 | * | |
62 | * This function initializes an opaque iterator struct which can then | |
63 | * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap | |
64 | * argument which is present in the header. It knows about extended | |
65 | * present headers and handles them. | |
66 | * | |
67 | * How to use: | |
68 | * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator | |
69 | * struct ieee80211_radiotap_iterator (no need to init the struct beforehand) | |
70 | * checking for a good 0 return code. Then loop calling | |
71 | * __ieee80211_radiotap_iterator_next()... it returns either 0, | |
72 | * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem. | |
73 | * The iterator's @this_arg member points to the start of the argument | |
74 | * associated with the current argument index that is present, which can be | |
75 | * found in the iterator's @this_arg_index member. This arg index corresponds | |
76 | * to the IEEE80211_RADIOTAP_... defines. | |
77 | * | |
78 | * Radiotap header length: | |
79 | * You can find the CPU-endian total radiotap header length in | |
80 | * iterator->max_length after executing ieee80211_radiotap_iterator_init() | |
81 | * successfully. | |
82 | * | |
83 | * Alignment Gotcha: | |
84 | * You must take care when dereferencing iterator.this_arg | |
85 | * for multibyte types... the pointer is not aligned. Use | |
86 | * get_unaligned((type *)iterator.this_arg) to dereference | |
87 | * iterator.this_arg for type "type" safely on all arches. | |
88 | * | |
89 | * Example code: | |
90 | * See Documentation/networking/radiotap-headers.txt | |
91 | */ | |
92 | ||
93 | int ieee80211_radiotap_iterator_init( | |
33e5a2f7 JB |
94 | struct ieee80211_radiotap_iterator *iterator, |
95 | struct ieee80211_radiotap_header *radiotap_header, | |
96 | int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns) | |
179f831b AG |
97 | { |
98 | /* Linux only supports version 0 radiotap format */ | |
99 | if (radiotap_header->it_version) | |
100 | return -EINVAL; | |
101 | ||
102 | /* sanity check for allowed length and radiotap length field */ | |
ae7245cb | 103 | if (max_length < get_unaligned_le16(&radiotap_header->it_len)) |
179f831b AG |
104 | return -EINVAL; |
105 | ||
33e5a2f7 JB |
106 | iterator->_rtheader = radiotap_header; |
107 | iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len); | |
108 | iterator->_arg_index = 0; | |
109 | iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present); | |
110 | iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header); | |
111 | iterator->_reset_on_ext = 0; | |
112 | iterator->_next_bitmap = &radiotap_header->it_present; | |
113 | iterator->_next_bitmap++; | |
114 | iterator->_vns = vns; | |
115 | iterator->current_namespace = &radiotap_ns; | |
116 | iterator->is_radiotap_ns = 1; | |
179f831b AG |
117 | |
118 | /* find payload start allowing for extended bitmap(s) */ | |
119 | ||
33e5a2f7 JB |
120 | if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) { |
121 | while (get_unaligned_le32(iterator->_arg) & | |
122 | (1 << IEEE80211_RADIOTAP_EXT)) { | |
123 | iterator->_arg += sizeof(uint32_t); | |
179f831b AG |
124 | |
125 | /* | |
126 | * check for insanity where the present bitmaps | |
127 | * keep claiming to extend up to or even beyond the | |
128 | * stated radiotap header length | |
129 | */ | |
130 | ||
33e5a2f7 JB |
131 | if ((unsigned long)iterator->_arg - |
132 | (unsigned long)iterator->_rtheader > | |
133 | (unsigned long)iterator->_max_length) | |
179f831b AG |
134 | return -EINVAL; |
135 | } | |
136 | ||
33e5a2f7 | 137 | iterator->_arg += sizeof(uint32_t); |
179f831b AG |
138 | |
139 | /* | |
140 | * no need to check again for blowing past stated radiotap | |
141 | * header length, because ieee80211_radiotap_iterator_next | |
142 | * checks it before it is dereferenced | |
143 | */ | |
144 | } | |
145 | ||
33e5a2f7 JB |
146 | iterator->this_arg = iterator->_arg; |
147 | ||
179f831b AG |
148 | /* we are all initialized happily */ |
149 | ||
150 | return 0; | |
151 | } | |
152 | EXPORT_SYMBOL(ieee80211_radiotap_iterator_init); | |
153 | ||
33e5a2f7 JB |
154 | static void find_ns(struct ieee80211_radiotap_iterator *iterator, |
155 | uint32_t oui, uint8_t subns) | |
156 | { | |
157 | int i; | |
158 | ||
159 | iterator->current_namespace = NULL; | |
160 | ||
161 | if (!iterator->_vns) | |
162 | return; | |
163 | ||
164 | for (i = 0; i < iterator->_vns->n_ns; i++) { | |
165 | if (iterator->_vns->ns[i].oui != oui) | |
166 | continue; | |
167 | if (iterator->_vns->ns[i].subns != subns) | |
168 | continue; | |
169 | ||
170 | iterator->current_namespace = &iterator->_vns->ns[i]; | |
171 | break; | |
172 | } | |
173 | } | |
174 | ||
175 | ||
179f831b AG |
176 | |
177 | /** | |
178 | * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg | |
179 | * @iterator: radiotap_iterator to move to next arg (if any) | |
180 | * | |
181 | * Returns: 0 if there is an argument to handle, | |
182 | * -ENOENT if there are no more args or -EINVAL | |
183 | * if there is something else wrong. | |
184 | * | |
185 | * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*) | |
186 | * in @this_arg_index and sets @this_arg to point to the | |
187 | * payload for the field. It takes care of alignment handling and extended | |
188 | * present fields. @this_arg can be changed by the caller (eg, | |
189 | * incremented to move inside a compound argument like | |
190 | * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in | |
191 | * little-endian format whatever the endianess of your CPU. | |
192 | * | |
193 | * Alignment Gotcha: | |
194 | * You must take care when dereferencing iterator.this_arg | |
195 | * for multibyte types... the pointer is not aligned. Use | |
196 | * get_unaligned((type *)iterator.this_arg) to dereference | |
197 | * iterator.this_arg for type "type" safely on all arches. | |
198 | */ | |
199 | ||
200 | int ieee80211_radiotap_iterator_next( | |
33e5a2f7 | 201 | struct ieee80211_radiotap_iterator *iterator) |
179f831b | 202 | { |
33e5a2f7 | 203 | while (1) { |
179f831b | 204 | int hit = 0; |
9ebad4ab | 205 | int pad, align, size, subns; |
33e5a2f7 | 206 | uint32_t oui; |
179f831b | 207 | |
33e5a2f7 JB |
208 | /* if no more EXT bits, that's it */ |
209 | if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT && | |
210 | !(iterator->_bitmap_shifter & 1)) | |
211 | return -ENOENT; | |
212 | ||
213 | if (!(iterator->_bitmap_shifter & 1)) | |
179f831b AG |
214 | goto next_entry; /* arg not present */ |
215 | ||
33e5a2f7 JB |
216 | /* get alignment/size of data */ |
217 | switch (iterator->_arg_index % 32) { | |
218 | case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: | |
219 | case IEEE80211_RADIOTAP_EXT: | |
220 | align = 1; | |
221 | size = 0; | |
222 | break; | |
223 | case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: | |
224 | align = 2; | |
225 | size = 6; | |
226 | break; | |
227 | default: | |
228 | if (!iterator->current_namespace || | |
229 | iterator->_arg_index >= iterator->current_namespace->n_bits) { | |
230 | if (iterator->current_namespace == &radiotap_ns) | |
231 | return -ENOENT; | |
232 | align = 0; | |
233 | } else { | |
234 | align = iterator->current_namespace->align_size[iterator->_arg_index].align; | |
235 | size = iterator->current_namespace->align_size[iterator->_arg_index].size; | |
236 | } | |
237 | if (!align) { | |
238 | /* skip all subsequent data */ | |
239 | iterator->_arg = iterator->_next_ns_data; | |
240 | /* give up on this namespace */ | |
241 | iterator->current_namespace = NULL; | |
242 | goto next_entry; | |
243 | } | |
244 | break; | |
245 | } | |
246 | ||
179f831b AG |
247 | /* |
248 | * arg is present, account for alignment padding | |
179f831b | 249 | * |
33e5a2f7 JB |
250 | * Note that these alignments are relative to the start |
251 | * of the radiotap header. There is no guarantee | |
179f831b AG |
252 | * that the radiotap header itself is aligned on any |
253 | * kind of boundary. | |
254 | * | |
33e5a2f7 JB |
255 | * The above is why get_unaligned() is used to dereference |
256 | * multibyte elements from the radiotap area. | |
179f831b AG |
257 | */ |
258 | ||
33e5a2f7 JB |
259 | pad = ((unsigned long)iterator->_arg - |
260 | (unsigned long)iterator->_rtheader) & (align - 1); | |
179f831b AG |
261 | |
262 | if (pad) | |
33e5a2f7 | 263 | iterator->_arg += align - pad; |
179f831b | 264 | |
9ebad4ab JB |
265 | if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) { |
266 | int vnslen; | |
267 | ||
268 | if ((unsigned long)iterator->_arg + size - | |
269 | (unsigned long)iterator->_rtheader > | |
270 | (unsigned long)iterator->_max_length) | |
271 | return -EINVAL; | |
272 | ||
273 | oui = (*iterator->_arg << 16) | | |
274 | (*(iterator->_arg + 1) << 8) | | |
275 | *(iterator->_arg + 2); | |
276 | subns = *(iterator->_arg + 3); | |
277 | ||
278 | find_ns(iterator, oui, subns); | |
279 | ||
280 | vnslen = get_unaligned_le16(iterator->_arg + 4); | |
281 | iterator->_next_ns_data = iterator->_arg + size + vnslen; | |
282 | if (!iterator->current_namespace) | |
283 | size += vnslen; | |
284 | } | |
285 | ||
179f831b AG |
286 | /* |
287 | * this is what we will return to user, but we need to | |
288 | * move on first so next call has something fresh to test | |
289 | */ | |
33e5a2f7 JB |
290 | iterator->this_arg_index = iterator->_arg_index; |
291 | iterator->this_arg = iterator->_arg; | |
292 | iterator->this_arg_size = size; | |
179f831b AG |
293 | |
294 | /* internally move on the size of this arg */ | |
33e5a2f7 | 295 | iterator->_arg += size; |
179f831b AG |
296 | |
297 | /* | |
298 | * check for insanity where we are given a bitmap that | |
299 | * claims to have more arg content than the length of the | |
300 | * radiotap section. We will normally end up equalling this | |
301 | * max_length on the last arg, never exceeding it. | |
302 | */ | |
303 | ||
33e5a2f7 JB |
304 | if ((unsigned long)iterator->_arg - |
305 | (unsigned long)iterator->_rtheader > | |
306 | (unsigned long)iterator->_max_length) | |
179f831b AG |
307 | return -EINVAL; |
308 | ||
33e5a2f7 JB |
309 | /* these special ones are valid in each bitmap word */ |
310 | switch (iterator->_arg_index % 32) { | |
311 | case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: | |
33e5a2f7 JB |
312 | iterator->_reset_on_ext = 1; |
313 | ||
33e5a2f7 | 314 | iterator->is_radiotap_ns = 0; |
9ebad4ab JB |
315 | /* |
316 | * If parser didn't register this vendor | |
317 | * namespace with us, allow it to show it | |
318 | * as 'raw. Do do that, set argument index | |
319 | * to vendor namespace. | |
320 | */ | |
33e5a2f7 JB |
321 | iterator->this_arg_index = |
322 | IEEE80211_RADIOTAP_VENDOR_NAMESPACE; | |
9ebad4ab JB |
323 | if (!iterator->current_namespace) |
324 | hit = 1; | |
325 | goto next_entry; | |
33e5a2f7 | 326 | case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: |
33e5a2f7 JB |
327 | iterator->_reset_on_ext = 1; |
328 | iterator->current_namespace = &radiotap_ns; | |
329 | iterator->is_radiotap_ns = 1; | |
9ebad4ab | 330 | goto next_entry; |
33e5a2f7 JB |
331 | case IEEE80211_RADIOTAP_EXT: |
332 | /* | |
333 | * bit 31 was set, there is more | |
334 | * -- move to next u32 bitmap | |
335 | */ | |
336 | iterator->_bitmap_shifter = | |
337 | get_unaligned_le32(iterator->_next_bitmap); | |
338 | iterator->_next_bitmap++; | |
339 | if (iterator->_reset_on_ext) | |
340 | iterator->_arg_index = 0; | |
341 | else | |
342 | iterator->_arg_index++; | |
343 | iterator->_reset_on_ext = 0; | |
344 | break; | |
345 | default: | |
346 | /* we've got a hit! */ | |
347 | hit = 1; | |
348 | next_entry: | |
349 | iterator->_bitmap_shifter >>= 1; | |
350 | iterator->_arg_index++; | |
351 | } | |
179f831b AG |
352 | |
353 | /* if we found a valid arg earlier, return it now */ | |
354 | if (hit) | |
355 | return 0; | |
356 | } | |
179f831b AG |
357 | } |
358 | EXPORT_SYMBOL(ieee80211_radiotap_iterator_next); |