1 /*
2 * WPA Supplicant - Layer2 packet handling with Linux packet sockets
3 * Copyright (c) 2003-2015, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9 #include "includes.h"
10 #include <sys/ioctl.h>
11 #include <netpacket/packet.h>
12 #include <net/if.h>
13 #include <linux/filter.h>
14
15 #include "common.h"
16 #include "eloop.h"
17 #include "crypto/sha1.h"
18 #include "crypto/crypto.h"
19 #include "l2_packet.h"
20
21
22 struct l2_packet_data {
23 int fd; /* packet socket for EAPOL frames */
24 char ifname[IFNAMSIZ + 1];
25 int ifindex;
26 u8 own_addr[ETH_ALEN];
27 void (*rx_callback)(void *ctx, const u8 *src_addr,
28 const u8 *buf, size_t len);
29 void *rx_callback_ctx;
30 int l2_hdr; /* whether to include layer 2 (Ethernet) header data
31 * buffers */
32
33 /* For working around Linux packet socket behavior and regression. */
34 int fd_br_rx;
35 int last_from_br;
36 u8 last_hash[SHA1_MAC_LEN];
37 unsigned int num_rx, num_rx_br;
38 };
39
40 /* Generated by 'sudo tcpdump -s 3000 -dd greater 278 and ip and udp and
41 * src port bootps and dst port bootpc'
42 */
43 static struct sock_filter dhcp_sock_filter_insns[] = {
44 { 0x80, 0, 0, 0x00000000 },
45 { 0x35, 0, 12, 0x00000116 },
46 { 0x28, 0, 0, 0x0000000c },
47 { 0x15, 0, 10, 0x00000800 },
48 { 0x30, 0, 0, 0x00000017 },
49 { 0x15, 0, 8, 0x00000011 },
50 { 0x28, 0, 0, 0x00000014 },
51 { 0x45, 6, 0, 0x00001fff },
52 { 0xb1, 0, 0, 0x0000000e },
53 { 0x48, 0, 0, 0x0000000e },
54 { 0x15, 0, 3, 0x00000043 },
55 { 0x48, 0, 0, 0x00000010 },
56 { 0x15, 0, 1, 0x00000044 },
57 { 0x6, 0, 0, 0x00000bb8 },
58 { 0x6, 0, 0, 0x00000000 },
59 };
60
61 static const struct sock_fprog dhcp_sock_filter = {
62 .len = ARRAY_SIZE(dhcp_sock_filter_insns),
63 .filter = dhcp_sock_filter_insns,
64 };
65
66
67 /* Generated by 'sudo tcpdump -dd -s 1500 multicast and ip6[6]=58' */
68 static struct sock_filter ndisc_sock_filter_insns[] = {
69 { 0x30, 0, 0, 0x00000000 },
70 { 0x45, 0, 5, 0x00000001 },
71 { 0x28, 0, 0, 0x0000000c },
72 { 0x15, 0, 3, 0x000086dd },
73 { 0x30, 0, 0, 0x00000014 },
74 { 0x15, 0, 1, 0x0000003a },
75 { 0x6, 0, 0, 0x000005dc },
76 { 0x6, 0, 0, 0x00000000 },
77 };
78
79 static const struct sock_fprog ndisc_sock_filter = {
80 .len = ARRAY_SIZE(ndisc_sock_filter_insns),
81 .filter = ndisc_sock_filter_insns,
82 };
83
84
l2_packet_get_own_addr(struct l2_packet_data * l2,u8 * addr)85 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
86 {
87 os_memcpy(addr, l2->own_addr, ETH_ALEN);
88 return 0;
89 }
90
91
l2_packet_send(struct l2_packet_data * l2,const u8 * dst_addr,u16 proto,const u8 * buf,size_t len)92 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
93 const u8 *buf, size_t len)
94 {
95 int ret;
96 if (l2 == NULL)
97 return -1;
98 if (l2->l2_hdr) {
99 ret = send(l2->fd, buf, len, 0);
100 if (ret < 0)
101 wpa_printf(MSG_ERROR, "l2_packet_send - send: %s",
102 strerror(errno));
103 } else {
104 struct sockaddr_ll ll;
105 os_memset(&ll, 0, sizeof(ll));
106 ll.sll_family = AF_PACKET;
107 ll.sll_ifindex = l2->ifindex;
108 ll.sll_protocol = htons(proto);
109 ll.sll_halen = ETH_ALEN;
110 os_memcpy(ll.sll_addr, dst_addr, ETH_ALEN);
111 ret = sendto(l2->fd, buf, len, 0, (struct sockaddr *) &ll,
112 sizeof(ll));
113 if (ret < 0) {
114 wpa_printf(MSG_ERROR, "l2_packet_send - sendto: %s",
115 strerror(errno));
116 }
117 }
118 return ret;
119 }
120
121
l2_packet_receive(int sock,void * eloop_ctx,void * sock_ctx)122 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
123 {
124 struct l2_packet_data *l2 = eloop_ctx;
125 u8 buf[2300];
126 int res;
127 struct sockaddr_ll ll;
128 socklen_t fromlen;
129
130 l2->num_rx++;
131 os_memset(&ll, 0, sizeof(ll));
132 fromlen = sizeof(ll);
133 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
134 &fromlen);
135 if (res < 0) {
136 wpa_printf(MSG_DEBUG, "l2_packet_receive - recvfrom: %s",
137 strerror(errno));
138 return;
139 }
140
141 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
142 __func__, MAC2STR(ll.sll_addr), (int) res);
143
144 if (l2->fd_br_rx >= 0) {
145 u8 hash[SHA1_MAC_LEN];
146 const u8 *addr[1];
147 size_t len[1];
148
149 /*
150 * Close the workaround socket if the kernel version seems to be
151 * able to deliver packets through the packet socket before
152 * authorization has been completed (in dormant state).
153 */
154 if (l2->num_rx_br <= 1) {
155 wpa_printf(MSG_DEBUG,
156 "l2_packet_receive: Main packet socket for %s seems to have working RX - close workaround bridge socket",
157 l2->ifname);
158 eloop_unregister_read_sock(l2->fd_br_rx);
159 close(l2->fd_br_rx);
160 l2->fd_br_rx = -1;
161 }
162
163 addr[0] = buf;
164 len[0] = res;
165 sha1_vector(1, addr, len, hash);
166 if (l2->last_from_br &&
167 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
168 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX",
169 __func__);
170 return;
171 }
172 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
173 }
174
175 l2->last_from_br = 0;
176 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
177 }
178
179
l2_packet_receive_br(int sock,void * eloop_ctx,void * sock_ctx)180 static void l2_packet_receive_br(int sock, void *eloop_ctx, void *sock_ctx)
181 {
182 struct l2_packet_data *l2 = eloop_ctx;
183 u8 buf[2300];
184 int res;
185 struct sockaddr_ll ll;
186 socklen_t fromlen;
187 u8 hash[SHA1_MAC_LEN];
188 const u8 *addr[1];
189 size_t len[1];
190
191 l2->num_rx_br++;
192 os_memset(&ll, 0, sizeof(ll));
193 fromlen = sizeof(ll);
194 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
195 &fromlen);
196 if (res < 0) {
197 wpa_printf(MSG_DEBUG, "l2_packet_receive_br - recvfrom: %s",
198 strerror(errno));
199 return;
200 }
201
202 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
203 __func__, MAC2STR(ll.sll_addr), (int) res);
204
205 addr[0] = buf;
206 len[0] = res;
207 sha1_vector(1, addr, len, hash);
208 if (!l2->last_from_br &&
209 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
210 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX", __func__);
211 return;
212 }
213 l2->last_from_br = 1;
214 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
215 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
216 }
217
218
l2_packet_init(const char * ifname,const u8 * own_addr,unsigned short protocol,void (* rx_callback)(void * ctx,const u8 * src_addr,const u8 * buf,size_t len),void * rx_callback_ctx,int l2_hdr)219 struct l2_packet_data * l2_packet_init(
220 const char *ifname, const u8 *own_addr, unsigned short protocol,
221 void (*rx_callback)(void *ctx, const u8 *src_addr,
222 const u8 *buf, size_t len),
223 void *rx_callback_ctx, int l2_hdr)
224 {
225 struct l2_packet_data *l2;
226 struct ifreq ifr;
227 struct sockaddr_ll ll;
228
229 l2 = os_zalloc(sizeof(struct l2_packet_data));
230 if (l2 == NULL)
231 return NULL;
232 os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
233 l2->rx_callback = rx_callback;
234 l2->rx_callback_ctx = rx_callback_ctx;
235 l2->l2_hdr = l2_hdr;
236 l2->fd_br_rx = -1;
237
238 l2->fd = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
239 htons(protocol));
240 if (l2->fd < 0) {
241 wpa_printf(MSG_ERROR, "%s: socket(PF_PACKET): %s",
242 __func__, strerror(errno));
243 os_free(l2);
244 return NULL;
245 }
246 os_memset(&ifr, 0, sizeof(ifr));
247 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
248 if (ioctl(l2->fd, SIOCGIFINDEX, &ifr) < 0) {
249 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFINDEX]: %s",
250 __func__, strerror(errno));
251 close(l2->fd);
252 os_free(l2);
253 return NULL;
254 }
255 l2->ifindex = ifr.ifr_ifindex;
256
257 os_memset(&ll, 0, sizeof(ll));
258 ll.sll_family = PF_PACKET;
259 ll.sll_ifindex = ifr.ifr_ifindex;
260 ll.sll_protocol = htons(protocol);
261 if (bind(l2->fd, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
262 wpa_printf(MSG_ERROR, "%s: bind[PF_PACKET]: %s",
263 __func__, strerror(errno));
264 close(l2->fd);
265 os_free(l2);
266 return NULL;
267 }
268
269 if (ioctl(l2->fd, SIOCGIFHWADDR, &ifr) < 0) {
270 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFHWADDR]: %s",
271 __func__, strerror(errno));
272 close(l2->fd);
273 os_free(l2);
274 return NULL;
275 }
276 os_memcpy(l2->own_addr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
277
278 eloop_register_read_sock(l2->fd, l2_packet_receive, l2, NULL);
279
280 return l2;
281 }
282
283
l2_packet_init_bridge(const char * br_ifname,const char * ifname,const u8 * own_addr,unsigned short protocol,void (* rx_callback)(void * ctx,const u8 * src_addr,const u8 * buf,size_t len),void * rx_callback_ctx,int l2_hdr)284 struct l2_packet_data * l2_packet_init_bridge(
285 const char *br_ifname, const char *ifname, const u8 *own_addr,
286 unsigned short protocol,
287 void (*rx_callback)(void *ctx, const u8 *src_addr,
288 const u8 *buf, size_t len),
289 void *rx_callback_ctx, int l2_hdr)
290 {
291 struct l2_packet_data *l2;
292 struct sock_filter ethertype_sock_filter_insns[] = {
293 /* Load ethertype */
294 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 2 * ETH_ALEN),
295 /* Jump over next statement if ethertype does not match */
296 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, protocol, 0, 1),
297 /* Ethertype match - return all */
298 BPF_STMT(BPF_RET | BPF_K, ~0),
299 /* No match - drop */
300 BPF_STMT(BPF_RET | BPF_K, 0)
301 };
302 const struct sock_fprog ethertype_sock_filter = {
303 .len = ARRAY_SIZE(ethertype_sock_filter_insns),
304 .filter = ethertype_sock_filter_insns,
305 };
306 struct sockaddr_ll ll;
307
308 l2 = l2_packet_init(br_ifname, own_addr, protocol, rx_callback,
309 rx_callback_ctx, l2_hdr);
310 if (!l2)
311 return NULL;
312
313 /*
314 * The Linux packet socket behavior has changed over the years and there
315 * is an inconvenient regression in it that breaks RX for a specific
316 * protocol from interfaces in a bridge when that interface is not in
317 * fully operation state (i.e., when in station mode and not completed
318 * authorization). To work around this, register ETH_P_ALL version of
319 * the packet socket bound to the real netdev and use socket filter to
320 * match the ethertype value. This version is less efficient, but
321 * required for functionality with many kernel version. If the main
322 * packet socket is found to be working, this less efficient version
323 * gets closed automatically.
324 */
325
326 l2->fd_br_rx = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
327 htons(ETH_P_ALL));
328 if (l2->fd_br_rx < 0) {
329 wpa_printf(MSG_DEBUG, "%s: socket(PF_PACKET-fd_br_rx): %s",
330 __func__, strerror(errno));
331 /* try to continue without the workaround RX socket */
332 return l2;
333 }
334
335 os_memset(&ll, 0, sizeof(ll));
336 ll.sll_family = PF_PACKET;
337 ll.sll_ifindex = if_nametoindex(ifname);
338 ll.sll_protocol = htons(ETH_P_ALL);
339 if (bind(l2->fd_br_rx, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
340 wpa_printf(MSG_DEBUG, "%s: bind[PF_PACKET-fd_br_rx]: %s",
341 __func__, strerror(errno));
342 /* try to continue without the workaround RX socket */
343 close(l2->fd_br_rx);
344 l2->fd_br_rx = -1;
345 return l2;
346 }
347
348 if (setsockopt(l2->fd_br_rx, SOL_SOCKET, SO_ATTACH_FILTER,
349 ðertype_sock_filter, sizeof(struct sock_fprog))) {
350 wpa_printf(MSG_DEBUG,
351 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
352 strerror(errno));
353 /* try to continue without the workaround RX socket */
354 close(l2->fd_br_rx);
355 l2->fd_br_rx = -1;
356 return l2;
357 }
358
359 eloop_register_read_sock(l2->fd_br_rx, l2_packet_receive_br, l2, NULL);
360
361 return l2;
362 }
363
364
l2_packet_deinit(struct l2_packet_data * l2)365 void l2_packet_deinit(struct l2_packet_data *l2)
366 {
367 if (l2 == NULL)
368 return;
369
370 if (l2->fd >= 0) {
371 eloop_unregister_read_sock(l2->fd);
372 close(l2->fd);
373 }
374
375 if (l2->fd_br_rx >= 0) {
376 eloop_unregister_read_sock(l2->fd_br_rx);
377 close(l2->fd_br_rx);
378 }
379
380 os_free(l2);
381 }
382
383
l2_packet_get_ip_addr(struct l2_packet_data * l2,char * buf,size_t len)384 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
385 {
386 int s;
387 struct ifreq ifr;
388 struct sockaddr_in *saddr;
389 size_t res;
390
391 s = socket(PF_INET, SOCK_DGRAM, 0);
392 if (s < 0) {
393 wpa_printf(MSG_ERROR, "%s: socket: %s",
394 __func__, strerror(errno));
395 return -1;
396 }
397 os_memset(&ifr, 0, sizeof(ifr));
398 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
399 if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
400 if (errno != EADDRNOTAVAIL)
401 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFADDR]: %s",
402 __func__, strerror(errno));
403 close(s);
404 return -1;
405 }
406 close(s);
407 saddr = aliasing_hide_typecast(&ifr.ifr_addr, struct sockaddr_in);
408 if (saddr->sin_family != AF_INET)
409 return -1;
410 res = os_strlcpy(buf, inet_ntoa(saddr->sin_addr), len);
411 if (res >= len)
412 return -1;
413 return 0;
414 }
415
416
l2_packet_notify_auth_start(struct l2_packet_data * l2)417 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
418 {
419 }
420
421
l2_packet_set_packet_filter(struct l2_packet_data * l2,enum l2_packet_filter_type type)422 int l2_packet_set_packet_filter(struct l2_packet_data *l2,
423 enum l2_packet_filter_type type)
424 {
425 const struct sock_fprog *sock_filter;
426
427 switch (type) {
428 case L2_PACKET_FILTER_DHCP:
429 sock_filter = &dhcp_sock_filter;
430 break;
431 case L2_PACKET_FILTER_NDISC:
432 sock_filter = &ndisc_sock_filter;
433 break;
434 default:
435 return -1;
436 }
437
438 if (setsockopt(l2->fd, SOL_SOCKET, SO_ATTACH_FILTER,
439 sock_filter, sizeof(struct sock_fprog))) {
440 wpa_printf(MSG_ERROR,
441 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
442 strerror(errno));
443 return -1;
444 }
445
446 return 0;
447 }
448