1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2014 Fraunhofer ITWM
4 *
5 * Written by:
6 * Phoebe Buckheister <phoebe.buckheister@itwm.fraunhofer.de>
7 */
8
9#include <linux/ieee802154.h>
10
11#include <net/mac802154.h>
12#include <net/ieee802154_netdev.h>
13
14static int
15ieee802154_hdr_push_addr(u8 *buf, const struct ieee802154_addr *addr,
16			 bool omit_pan)
17{
18	int pos = 0;
19
20	if (addr->mode == IEEE802154_ADDR_NONE)
21		return 0;
22
23	if (!omit_pan) {
24		memcpy(buf + pos, &addr->pan_id, 2);
25		pos += 2;
26	}
27
28	switch (addr->mode) {
29	case IEEE802154_ADDR_SHORT:
30		memcpy(buf + pos, &addr->short_addr, 2);
31		pos += 2;
32		break;
33
34	case IEEE802154_ADDR_LONG:
35		memcpy(buf + pos, &addr->extended_addr, IEEE802154_ADDR_LEN);
36		pos += IEEE802154_ADDR_LEN;
37		break;
38
39	default:
40		return -EINVAL;
41	}
42
43	return pos;
44}
45
46static int
47ieee802154_hdr_push_sechdr(u8 *buf, const struct ieee802154_sechdr *hdr)
48{
49	int pos = 5;
50
51	memcpy(buf, hdr, 1);
52	memcpy(buf + 1, &hdr->frame_counter, 4);
53
54	switch (hdr->key_id_mode) {
55	case IEEE802154_SCF_KEY_IMPLICIT:
56		return pos;
57
58	case IEEE802154_SCF_KEY_INDEX:
59		break;
60
61	case IEEE802154_SCF_KEY_SHORT_INDEX:
62		memcpy(buf + pos, &hdr->short_src, 4);
63		pos += 4;
64		break;
65
66	case IEEE802154_SCF_KEY_HW_INDEX:
67		memcpy(buf + pos, &hdr->extended_src, IEEE802154_ADDR_LEN);
68		pos += IEEE802154_ADDR_LEN;
69		break;
70	}
71
72	buf[pos++] = hdr->key_id;
73
74	return pos;
75}
76
77int
78ieee802154_hdr_push(struct sk_buff *skb, struct ieee802154_hdr *hdr)
79{
80	u8 buf[IEEE802154_MAX_HEADER_LEN];
81	int pos = 2;
82	int rc;
83	struct ieee802154_hdr_fc *fc = &hdr->fc;
84
85	buf[pos++] = hdr->seq;
86
87	fc->dest_addr_mode = hdr->dest.mode;
88
89	rc = ieee802154_hdr_push_addr(buf + pos, &hdr->dest, false);
90	if (rc < 0)
91		return -EINVAL;
92	pos += rc;
93
94	fc->source_addr_mode = hdr->source.mode;
95
96	if (hdr->source.pan_id == hdr->dest.pan_id &&
97	    hdr->dest.mode != IEEE802154_ADDR_NONE)
98		fc->intra_pan = true;
99
100	rc = ieee802154_hdr_push_addr(buf + pos, &hdr->source, fc->intra_pan);
101	if (rc < 0)
102		return -EINVAL;
103	pos += rc;
104
105	if (fc->security_enabled) {
106		fc->version = 1;
107
108		rc = ieee802154_hdr_push_sechdr(buf + pos, &hdr->sec);
109		if (rc < 0)
110			return -EINVAL;
111
112		pos += rc;
113	}
114
115	memcpy(buf, fc, 2);
116
117	memcpy(skb_push(skb, pos), buf, pos);
118
119	return pos;
120}
121EXPORT_SYMBOL_GPL(ieee802154_hdr_push);
122
123static int
124ieee802154_hdr_get_addr(const u8 *buf, int mode, bool omit_pan,
125			struct ieee802154_addr *addr)
126{
127	int pos = 0;
128
129	addr->mode = mode;
130
131	if (mode == IEEE802154_ADDR_NONE)
132		return 0;
133
134	if (!omit_pan) {
135		memcpy(&addr->pan_id, buf + pos, 2);
136		pos += 2;
137	}
138
139	if (mode == IEEE802154_ADDR_SHORT) {
140		memcpy(&addr->short_addr, buf + pos, 2);
141		return pos + 2;
142	} else {
143		memcpy(&addr->extended_addr, buf + pos, IEEE802154_ADDR_LEN);
144		return pos + IEEE802154_ADDR_LEN;
145	}
146}
147
148static int ieee802154_hdr_addr_len(int mode, bool omit_pan)
149{
150	int pan_len = omit_pan ? 0 : 2;
151
152	switch (mode) {
153	case IEEE802154_ADDR_NONE: return 0;
154	case IEEE802154_ADDR_SHORT: return 2 + pan_len;
155	case IEEE802154_ADDR_LONG: return IEEE802154_ADDR_LEN + pan_len;
156	default: return -EINVAL;
157	}
158}
159
160static int
161ieee802154_hdr_get_sechdr(const u8 *buf, struct ieee802154_sechdr *hdr)
162{
163	int pos = 5;
164
165	memcpy(hdr, buf, 1);
166	memcpy(&hdr->frame_counter, buf + 1, 4);
167
168	switch (hdr->key_id_mode) {
169	case IEEE802154_SCF_KEY_IMPLICIT:
170		return pos;
171
172	case IEEE802154_SCF_KEY_INDEX:
173		break;
174
175	case IEEE802154_SCF_KEY_SHORT_INDEX:
176		memcpy(&hdr->short_src, buf + pos, 4);
177		pos += 4;
178		break;
179
180	case IEEE802154_SCF_KEY_HW_INDEX:
181		memcpy(&hdr->extended_src, buf + pos, IEEE802154_ADDR_LEN);
182		pos += IEEE802154_ADDR_LEN;
183		break;
184	}
185
186	hdr->key_id = buf[pos++];
187
188	return pos;
189}
190
191static int ieee802154_sechdr_lengths[4] = {
192	[IEEE802154_SCF_KEY_IMPLICIT] = 5,
193	[IEEE802154_SCF_KEY_INDEX] = 6,
194	[IEEE802154_SCF_KEY_SHORT_INDEX] = 10,
195	[IEEE802154_SCF_KEY_HW_INDEX] = 14,
196};
197
198static int ieee802154_hdr_sechdr_len(u8 sc)
199{
200	return ieee802154_sechdr_lengths[IEEE802154_SCF_KEY_ID_MODE(sc)];
201}
202
203static int ieee802154_hdr_minlen(const struct ieee802154_hdr *hdr)
204{
205	int dlen, slen;
206
207	dlen = ieee802154_hdr_addr_len(hdr->fc.dest_addr_mode, false);
208	slen = ieee802154_hdr_addr_len(hdr->fc.source_addr_mode,
209				       hdr->fc.intra_pan);
210
211	if (slen < 0 || dlen < 0)
212		return -EINVAL;
213
214	return 3 + dlen + slen + hdr->fc.security_enabled;
215}
216
217static int
218ieee802154_hdr_get_addrs(const u8 *buf, struct ieee802154_hdr *hdr)
219{
220	int pos = 0;
221
222	pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.dest_addr_mode,
223				       false, &hdr->dest);
224	pos += ieee802154_hdr_get_addr(buf + pos, hdr->fc.source_addr_mode,
225				       hdr->fc.intra_pan, &hdr->source);
226
227	if (hdr->fc.intra_pan)
228		hdr->source.pan_id = hdr->dest.pan_id;
229
230	return pos;
231}
232
233int
234ieee802154_hdr_pull(struct sk_buff *skb, struct ieee802154_hdr *hdr)
235{
236	int pos = 3, rc;
237
238	if (!pskb_may_pull(skb, 3))
239		return -EINVAL;
240
241	memcpy(hdr, skb->data, 3);
242
243	rc = ieee802154_hdr_minlen(hdr);
244	if (rc < 0 || !pskb_may_pull(skb, rc))
245		return -EINVAL;
246
247	pos += ieee802154_hdr_get_addrs(skb->data + pos, hdr);
248
249	if (hdr->fc.security_enabled) {
250		int want = pos + ieee802154_hdr_sechdr_len(skb->data[pos]);
251
252		if (!pskb_may_pull(skb, want))
253			return -EINVAL;
254
255		pos += ieee802154_hdr_get_sechdr(skb->data + pos, &hdr->sec);
256	}
257
258	skb_pull(skb, pos);
259	return pos;
260}
261EXPORT_SYMBOL_GPL(ieee802154_hdr_pull);
262
263int
264ieee802154_hdr_peek_addrs(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
265{
266	const u8 *buf = skb_mac_header(skb);
267	int pos = 3, rc;
268
269	if (buf + 3 > skb_tail_pointer(skb))
270		return -EINVAL;
271
272	memcpy(hdr, buf, 3);
273
274	rc = ieee802154_hdr_minlen(hdr);
275	if (rc < 0 || buf + rc > skb_tail_pointer(skb))
276		return -EINVAL;
277
278	pos += ieee802154_hdr_get_addrs(buf + pos, hdr);
279	return pos;
280}
281EXPORT_SYMBOL_GPL(ieee802154_hdr_peek_addrs);
282
283int
284ieee802154_hdr_peek(const struct sk_buff *skb, struct ieee802154_hdr *hdr)
285{
286	const u8 *buf = skb_mac_header(skb);
287	int pos;
288
289	pos = ieee802154_hdr_peek_addrs(skb, hdr);
290	if (pos < 0)
291		return -EINVAL;
292
293	if (hdr->fc.security_enabled) {
294		u8 key_id_mode = IEEE802154_SCF_KEY_ID_MODE(*(buf + pos));
295		int want = pos + ieee802154_sechdr_lengths[key_id_mode];
296
297		if (buf + want > skb_tail_pointer(skb))
298			return -EINVAL;
299
300		pos += ieee802154_hdr_get_sechdr(buf + pos, &hdr->sec);
301	}
302
303	return pos;
304}
305EXPORT_SYMBOL_GPL(ieee802154_hdr_peek);
306
307int ieee802154_max_payload(const struct ieee802154_hdr *hdr)
308{
309	int hlen = ieee802154_hdr_minlen(hdr);
310
311	if (hdr->fc.security_enabled) {
312		hlen += ieee802154_sechdr_lengths[hdr->sec.key_id_mode] - 1;
313		hlen += ieee802154_sechdr_authtag_len(&hdr->sec);
314	}
315
316	return IEEE802154_MTU - hlen - IEEE802154_MFR_SIZE;
317}
318EXPORT_SYMBOL_GPL(ieee802154_max_payload);
319