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 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
34 /* For working around Linux packet socket behavior and regression. */
35 int fd_br_rx;
36 int last_from_br, last_from_br_prev;
37 u8 last_hash[SHA1_MAC_LEN];
38 u8 last_hash_prev[SHA1_MAC_LEN];
39 unsigned int num_rx_br;
40 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
41 };
42
43 /* Generated by 'sudo tcpdump -s 3000 -dd greater 278 and ip and udp and
44 * src port bootps and dst port bootpc'
45 */
46 static struct sock_filter dhcp_sock_filter_insns[] = {
47 { 0x80, 0, 0, 0x00000000 },
48 { 0x35, 0, 12, 0x00000116 },
49 { 0x28, 0, 0, 0x0000000c },
50 { 0x15, 0, 10, 0x00000800 },
51 { 0x30, 0, 0, 0x00000017 },
52 { 0x15, 0, 8, 0x00000011 },
53 { 0x28, 0, 0, 0x00000014 },
54 { 0x45, 6, 0, 0x00001fff },
55 { 0xb1, 0, 0, 0x0000000e },
56 { 0x48, 0, 0, 0x0000000e },
57 { 0x15, 0, 3, 0x00000043 },
58 { 0x48, 0, 0, 0x00000010 },
59 { 0x15, 0, 1, 0x00000044 },
60 { 0x6, 0, 0, 0x00000bb8 },
61 { 0x6, 0, 0, 0x00000000 },
62 };
63
64 static const struct sock_fprog dhcp_sock_filter = {
65 .len = ARRAY_SIZE(dhcp_sock_filter_insns),
66 .filter = dhcp_sock_filter_insns,
67 };
68
69
70 /* Generated by 'sudo tcpdump -dd -s 1500 multicast and ip6[6]=58' */
71 static struct sock_filter ndisc_sock_filter_insns[] = {
72 { 0x30, 0, 0, 0x00000000 },
73 { 0x45, 0, 5, 0x00000001 },
74 { 0x28, 0, 0, 0x0000000c },
75 { 0x15, 0, 3, 0x000086dd },
76 { 0x30, 0, 0, 0x00000014 },
77 { 0x15, 0, 1, 0x0000003a },
78 { 0x6, 0, 0, 0x000005dc },
79 { 0x6, 0, 0, 0x00000000 },
80 };
81
82 static const struct sock_fprog ndisc_sock_filter = {
83 .len = ARRAY_SIZE(ndisc_sock_filter_insns),
84 .filter = ndisc_sock_filter_insns,
85 };
86
87
l2_packet_get_own_addr(struct l2_packet_data * l2,u8 * addr)88 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
89 {
90 os_memcpy(addr, l2->own_addr, ETH_ALEN);
91 return 0;
92 }
93
94
l2_packet_send(struct l2_packet_data * l2,const u8 * dst_addr,u16 proto,const u8 * buf,size_t len)95 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
96 const u8 *buf, size_t len)
97 {
98 int ret;
99 if (l2 == NULL)
100 return -1;
101 if (l2->l2_hdr) {
102 ret = send(l2->fd, buf, len, 0);
103 if (ret < 0)
104 wpa_printf(MSG_ERROR, "l2_packet_send - send: %s",
105 strerror(errno));
106 } else {
107 struct sockaddr_ll ll;
108 os_memset(&ll, 0, sizeof(ll));
109 ll.sll_family = AF_PACKET;
110 ll.sll_ifindex = l2->ifindex;
111 ll.sll_protocol = htons(proto);
112 ll.sll_halen = ETH_ALEN;
113 os_memcpy(ll.sll_addr, dst_addr, ETH_ALEN);
114 ret = sendto(l2->fd, buf, len, 0, (struct sockaddr *) &ll,
115 sizeof(ll));
116 if (ret < 0) {
117 wpa_printf(MSG_ERROR, "l2_packet_send - sendto: %s",
118 strerror(errno));
119 }
120 }
121 return ret;
122 }
123
124
l2_packet_receive(int sock,void * eloop_ctx,void * sock_ctx)125 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
126 {
127 struct l2_packet_data *l2 = eloop_ctx;
128 u8 buf[2300];
129 int res;
130 struct sockaddr_ll ll;
131 socklen_t fromlen;
132
133 os_memset(&ll, 0, sizeof(ll));
134 fromlen = sizeof(ll);
135 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
136 &fromlen);
137 if (res < 0) {
138 wpa_printf(MSG_DEBUG, "l2_packet_receive - recvfrom: %s",
139 strerror(errno));
140 return;
141 }
142
143 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
144 __func__, MAC2STR(ll.sll_addr), (int) res);
145
146 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
147 if (l2->fd_br_rx >= 0) {
148 u8 hash[SHA1_MAC_LEN];
149 const u8 *addr[1];
150 size_t len[1];
151
152 /*
153 * Close the workaround socket if the kernel version seems to be
154 * able to deliver packets through the packet socket before
155 * authorization has been completed (in dormant state).
156 */
157 if (l2->num_rx_br <= 1) {
158 wpa_printf(MSG_DEBUG,
159 "l2_packet_receive: Main packet socket for %s seems to have working RX - close workaround bridge socket",
160 l2->ifname);
161 eloop_unregister_read_sock(l2->fd_br_rx);
162 close(l2->fd_br_rx);
163 l2->fd_br_rx = -1;
164 }
165
166 addr[0] = buf;
167 len[0] = res;
168 sha1_vector(1, addr, len, hash);
169 if (l2->last_from_br &&
170 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
171 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX",
172 __func__);
173 return;
174 }
175 if (l2->last_from_br_prev &&
176 os_memcmp(hash, l2->last_hash_prev, SHA1_MAC_LEN) == 0) {
177 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX(prev)",
178 __func__);
179 return;
180 }
181 os_memcpy(l2->last_hash_prev, l2->last_hash, SHA1_MAC_LEN);
182 l2->last_from_br_prev = l2->last_from_br;
183 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
184 }
185
186 l2->last_from_br = 0;
187 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
188 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
189 }
190
191
192 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
l2_packet_receive_br(int sock,void * eloop_ctx,void * sock_ctx)193 static void l2_packet_receive_br(int sock, void *eloop_ctx, void *sock_ctx)
194 {
195 struct l2_packet_data *l2 = eloop_ctx;
196 u8 buf[2300];
197 int res;
198 struct sockaddr_ll ll;
199 socklen_t fromlen;
200 u8 hash[SHA1_MAC_LEN];
201 const u8 *addr[1];
202 size_t len[1];
203
204 l2->num_rx_br++;
205 os_memset(&ll, 0, sizeof(ll));
206 fromlen = sizeof(ll);
207 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
208 &fromlen);
209 if (res < 0) {
210 wpa_printf(MSG_DEBUG, "l2_packet_receive_br - recvfrom: %s",
211 strerror(errno));
212 return;
213 }
214
215 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
216 __func__, MAC2STR(ll.sll_addr), (int) res);
217
218 if (os_memcmp(ll.sll_addr, l2->own_addr, ETH_ALEN) == 0) {
219 wpa_printf(MSG_DEBUG, "%s: Drop RX of own frame", __func__);
220 return;
221 }
222
223 addr[0] = buf;
224 len[0] = res;
225 sha1_vector(1, addr, len, hash);
226 if (!l2->last_from_br &&
227 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
228 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX", __func__);
229 return;
230 }
231 if (!l2->last_from_br_prev &&
232 os_memcmp(hash, l2->last_hash_prev, SHA1_MAC_LEN) == 0) {
233 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX(prev)", __func__);
234 return;
235 }
236 os_memcpy(l2->last_hash_prev, l2->last_hash, SHA1_MAC_LEN);
237 l2->last_from_br_prev = l2->last_from_br;
238 l2->last_from_br = 1;
239 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
240 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
241 }
242 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
243
244
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)245 struct l2_packet_data * l2_packet_init(
246 const char *ifname, const u8 *own_addr, unsigned short protocol,
247 void (*rx_callback)(void *ctx, const u8 *src_addr,
248 const u8 *buf, size_t len),
249 void *rx_callback_ctx, int l2_hdr)
250 {
251 struct l2_packet_data *l2;
252 struct ifreq ifr;
253 struct sockaddr_ll ll;
254
255 l2 = os_zalloc(sizeof(struct l2_packet_data));
256 if (l2 == NULL)
257 return NULL;
258 os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
259 l2->rx_callback = rx_callback;
260 l2->rx_callback_ctx = rx_callback_ctx;
261 l2->l2_hdr = l2_hdr;
262 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
263 l2->fd_br_rx = -1;
264 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
265
266 l2->fd = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
267 htons(protocol));
268 if (l2->fd < 0) {
269 wpa_printf(MSG_ERROR, "%s: socket(PF_PACKET): %s",
270 __func__, strerror(errno));
271 os_free(l2);
272 return NULL;
273 }
274 os_memset(&ifr, 0, sizeof(ifr));
275 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
276 if (ioctl(l2->fd, SIOCGIFINDEX, &ifr) < 0) {
277 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFINDEX]: %s",
278 __func__, strerror(errno));
279 close(l2->fd);
280 os_free(l2);
281 return NULL;
282 }
283 l2->ifindex = ifr.ifr_ifindex;
284
285 os_memset(&ll, 0, sizeof(ll));
286 ll.sll_family = PF_PACKET;
287 ll.sll_ifindex = ifr.ifr_ifindex;
288 ll.sll_protocol = htons(protocol);
289 if (bind(l2->fd, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
290 wpa_printf(MSG_ERROR, "%s: bind[PF_PACKET]: %s",
291 __func__, strerror(errno));
292 close(l2->fd);
293 os_free(l2);
294 return NULL;
295 }
296
297 if (ioctl(l2->fd, SIOCGIFHWADDR, &ifr) < 0) {
298 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFHWADDR]: %s",
299 __func__, strerror(errno));
300 close(l2->fd);
301 os_free(l2);
302 return NULL;
303 }
304 os_memcpy(l2->own_addr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
305
306 eloop_register_read_sock(l2->fd, l2_packet_receive, l2, NULL);
307
308 return l2;
309 }
310
311
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)312 struct l2_packet_data * l2_packet_init_bridge(
313 const char *br_ifname, const char *ifname, const u8 *own_addr,
314 unsigned short protocol,
315 void (*rx_callback)(void *ctx, const u8 *src_addr,
316 const u8 *buf, size_t len),
317 void *rx_callback_ctx, int l2_hdr)
318 {
319 struct l2_packet_data *l2;
320 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
321 struct sock_filter ethertype_sock_filter_insns[] = {
322 /* Load ethertype */
323 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 2 * ETH_ALEN),
324 /* Jump over next statement if ethertype does not match */
325 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, protocol, 0, 1),
326 /* Ethertype match - return all */
327 BPF_STMT(BPF_RET | BPF_K, ~0),
328 /* No match - drop */
329 BPF_STMT(BPF_RET | BPF_K, 0)
330 };
331 const struct sock_fprog ethertype_sock_filter = {
332 .len = ARRAY_SIZE(ethertype_sock_filter_insns),
333 .filter = ethertype_sock_filter_insns,
334 };
335 struct sockaddr_ll ll;
336 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
337
338 l2 = l2_packet_init(br_ifname, own_addr, protocol, rx_callback,
339 rx_callback_ctx, l2_hdr);
340 if (!l2)
341 return NULL;
342
343 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
344 /*
345 * The Linux packet socket behavior has changed over the years and there
346 * is an inconvenient regression in it that breaks RX for a specific
347 * protocol from interfaces in a bridge when that interface is not in
348 * fully operation state (i.e., when in station mode and not completed
349 * authorization). To work around this, register ETH_P_ALL version of
350 * the packet socket bound to the real netdev and use socket filter to
351 * match the ethertype value. This version is less efficient, but
352 * required for functionality with many kernel version. If the main
353 * packet socket is found to be working, this less efficient version
354 * gets closed automatically.
355 */
356
357 l2->fd_br_rx = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
358 htons(ETH_P_ALL));
359 if (l2->fd_br_rx < 0) {
360 wpa_printf(MSG_DEBUG, "%s: socket(PF_PACKET-fd_br_rx): %s",
361 __func__, strerror(errno));
362 /* try to continue without the workaround RX socket */
363 return l2;
364 }
365
366 os_memset(&ll, 0, sizeof(ll));
367 ll.sll_family = PF_PACKET;
368 ll.sll_ifindex = if_nametoindex(ifname);
369 ll.sll_protocol = htons(ETH_P_ALL);
370 if (bind(l2->fd_br_rx, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
371 wpa_printf(MSG_DEBUG, "%s: bind[PF_PACKET-fd_br_rx]: %s",
372 __func__, strerror(errno));
373 /* try to continue without the workaround RX socket */
374 close(l2->fd_br_rx);
375 l2->fd_br_rx = -1;
376 return l2;
377 }
378
379 if (setsockopt(l2->fd_br_rx, SOL_SOCKET, SO_ATTACH_FILTER,
380 ðertype_sock_filter, sizeof(struct sock_fprog))) {
381 wpa_printf(MSG_DEBUG,
382 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
383 strerror(errno));
384 /* try to continue without the workaround RX socket */
385 close(l2->fd_br_rx);
386 l2->fd_br_rx = -1;
387 return l2;
388 }
389
390 eloop_register_read_sock(l2->fd_br_rx, l2_packet_receive_br, l2, NULL);
391 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
392
393 return l2;
394 }
395
396
l2_packet_deinit(struct l2_packet_data * l2)397 void l2_packet_deinit(struct l2_packet_data *l2)
398 {
399 if (l2 == NULL)
400 return;
401
402 if (l2->fd >= 0) {
403 eloop_unregister_read_sock(l2->fd);
404 close(l2->fd);
405 }
406
407 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
408 if (l2->fd_br_rx >= 0) {
409 eloop_unregister_read_sock(l2->fd_br_rx);
410 close(l2->fd_br_rx);
411 }
412 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
413
414 os_free(l2);
415 }
416
417
l2_packet_get_ip_addr(struct l2_packet_data * l2,char * buf,size_t len)418 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
419 {
420 int s;
421 struct ifreq ifr;
422 struct sockaddr_in *saddr;
423 size_t res;
424
425 s = socket(PF_INET, SOCK_DGRAM, 0);
426 if (s < 0) {
427 wpa_printf(MSG_ERROR, "%s: socket: %s",
428 __func__, strerror(errno));
429 return -1;
430 }
431 os_memset(&ifr, 0, sizeof(ifr));
432 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
433 if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
434 if (errno != EADDRNOTAVAIL)
435 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFADDR]: %s",
436 __func__, strerror(errno));
437 close(s);
438 return -1;
439 }
440 close(s);
441 saddr = aliasing_hide_typecast(&ifr.ifr_addr, struct sockaddr_in);
442 if (saddr->sin_family != AF_INET)
443 return -1;
444 res = os_strlcpy(buf, inet_ntoa(saddr->sin_addr), len);
445 if (res >= len)
446 return -1;
447 return 0;
448 }
449
450
l2_packet_notify_auth_start(struct l2_packet_data * l2)451 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
452 {
453 }
454
455
l2_packet_set_packet_filter(struct l2_packet_data * l2,enum l2_packet_filter_type type)456 int l2_packet_set_packet_filter(struct l2_packet_data *l2,
457 enum l2_packet_filter_type type)
458 {
459 const struct sock_fprog *sock_filter;
460
461 switch (type) {
462 case L2_PACKET_FILTER_DHCP:
463 sock_filter = &dhcp_sock_filter;
464 break;
465 case L2_PACKET_FILTER_NDISC:
466 sock_filter = &ndisc_sock_filter;
467 break;
468 default:
469 return -1;
470 }
471
472 if (setsockopt(l2->fd, SOL_SOCKET, SO_ATTACH_FILTER,
473 sock_filter, sizeof(struct sock_fprog))) {
474 wpa_printf(MSG_ERROR,
475 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
476 strerror(errno));
477 return -1;
478 }
479
480 return 0;
481 }
482