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 /* drop packet if skb->pkt_type is PACKET_OTHERHOST (0x03). Generated by:
88 * $ bpfc - <<EOF
89 * > ldb #type
90 * > jeq #0x03, drop
91 * > pass: ret #-1
92 * > drop: ret #0
93 * > EOF
94 */
95 static struct sock_filter pkt_type_filter_insns[] = {
96 { 0x30, 0, 0, 0xfffff004 },
97 { 0x15, 1, 0, 0x00000003 },
98 { 0x6, 0, 0, 0xffffffff },
99 { 0x6, 0, 0, 0x00000000 },
100 };
101
102 static const struct sock_fprog pkt_type_sock_filter = {
103 .len = ARRAY_SIZE(pkt_type_filter_insns),
104 .filter = pkt_type_filter_insns,
105 };
106
107
l2_packet_get_own_addr(struct l2_packet_data * l2,u8 * addr)108 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
109 {
110 os_memcpy(addr, l2->own_addr, ETH_ALEN);
111 return 0;
112 }
113
114
l2_packet_send(struct l2_packet_data * l2,const u8 * dst_addr,u16 proto,const u8 * buf,size_t len)115 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
116 const u8 *buf, size_t len)
117 {
118 int ret;
119
120 if (TEST_FAIL())
121 return -1;
122 if (l2 == NULL)
123 return -1;
124 if (l2->l2_hdr) {
125 ret = send(l2->fd, buf, len, 0);
126 if (ret < 0)
127 wpa_printf(MSG_ERROR, "l2_packet_send - send: %s",
128 strerror(errno));
129 } else {
130 struct sockaddr_ll ll;
131 os_memset(&ll, 0, sizeof(ll));
132 ll.sll_family = AF_PACKET;
133 ll.sll_ifindex = l2->ifindex;
134 ll.sll_protocol = htons(proto);
135 ll.sll_halen = ETH_ALEN;
136 os_memcpy(ll.sll_addr, dst_addr, ETH_ALEN);
137 ret = sendto(l2->fd, buf, len, 0, (struct sockaddr *) &ll,
138 sizeof(ll));
139 if (ret < 0) {
140 wpa_printf(MSG_ERROR, "l2_packet_send - sendto: %s",
141 strerror(errno));
142 }
143 }
144 return ret;
145 }
146
147
l2_packet_receive(int sock,void * eloop_ctx,void * sock_ctx)148 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
149 {
150 struct l2_packet_data *l2 = eloop_ctx;
151 u8 buf[2300];
152 int res;
153 struct sockaddr_ll ll;
154 socklen_t fromlen;
155
156 os_memset(&ll, 0, sizeof(ll));
157 fromlen = sizeof(ll);
158 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
159 &fromlen);
160 if (res < 0) {
161 wpa_printf(MSG_DEBUG, "l2_packet_receive - recvfrom: %s",
162 strerror(errno));
163 return;
164 }
165
166 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
167 __func__, MAC2STR(ll.sll_addr), (int) res);
168
169 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
170 if (l2->fd_br_rx >= 0) {
171 u8 hash[SHA1_MAC_LEN];
172 const u8 *addr[1];
173 size_t len[1];
174 const struct l2_ethhdr *eth = (const struct l2_ethhdr *) buf;
175
176 /*
177 * Close the workaround socket if the kernel version seems to be
178 * able to deliver packets through the packet socket before
179 * authorization has been completed (in dormant state).
180 */
181 if (l2->num_rx_br <= 1 &&
182 (os_memcmp(eth->h_dest, l2->own_addr, ETH_ALEN) == 0 ||
183 is_multicast_ether_addr(eth->h_dest))) {
184 wpa_printf(MSG_DEBUG,
185 "l2_packet_receive: Main packet socket for %s seems to have working RX - close workaround bridge socket",
186 l2->ifname);
187 eloop_unregister_read_sock(l2->fd_br_rx);
188 close(l2->fd_br_rx);
189 l2->fd_br_rx = -1;
190 }
191
192 addr[0] = buf;
193 len[0] = res;
194 sha1_vector(1, addr, len, hash);
195 if (l2->last_from_br &&
196 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
197 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX",
198 __func__);
199 return;
200 }
201 if (l2->last_from_br_prev &&
202 os_memcmp(hash, l2->last_hash_prev, SHA1_MAC_LEN) == 0) {
203 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX(prev)",
204 __func__);
205 return;
206 }
207 os_memcpy(l2->last_hash_prev, l2->last_hash, SHA1_MAC_LEN);
208 l2->last_from_br_prev = l2->last_from_br;
209 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
210 }
211
212 l2->last_from_br = 0;
213 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
214 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
215 }
216
217
218 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
l2_packet_receive_br(int sock,void * eloop_ctx,void * sock_ctx)219 static void l2_packet_receive_br(int sock, void *eloop_ctx, void *sock_ctx)
220 {
221 struct l2_packet_data *l2 = eloop_ctx;
222 u8 buf[2300];
223 int res;
224 struct sockaddr_ll ll;
225 socklen_t fromlen;
226 u8 hash[SHA1_MAC_LEN];
227 const u8 *addr[1];
228 size_t len[1];
229
230 l2->num_rx_br++;
231 os_memset(&ll, 0, sizeof(ll));
232 fromlen = sizeof(ll);
233 res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &ll,
234 &fromlen);
235 if (res < 0) {
236 wpa_printf(MSG_DEBUG, "l2_packet_receive_br - recvfrom: %s",
237 strerror(errno));
238 return;
239 }
240
241 wpa_printf(MSG_DEBUG, "%s: src=" MACSTR " len=%d",
242 __func__, MAC2STR(ll.sll_addr), (int) res);
243
244 if (os_memcmp(ll.sll_addr, l2->own_addr, ETH_ALEN) == 0) {
245 wpa_printf(MSG_DEBUG, "%s: Drop RX of own frame", __func__);
246 return;
247 }
248
249 addr[0] = buf;
250 len[0] = res;
251 sha1_vector(1, addr, len, hash);
252 if (!l2->last_from_br &&
253 os_memcmp(hash, l2->last_hash, SHA1_MAC_LEN) == 0) {
254 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX", __func__);
255 return;
256 }
257 if (!l2->last_from_br_prev &&
258 os_memcmp(hash, l2->last_hash_prev, SHA1_MAC_LEN) == 0) {
259 wpa_printf(MSG_DEBUG, "%s: Drop duplicate RX(prev)", __func__);
260 return;
261 }
262 os_memcpy(l2->last_hash_prev, l2->last_hash, SHA1_MAC_LEN);
263 l2->last_from_br_prev = l2->last_from_br;
264 l2->last_from_br = 1;
265 os_memcpy(l2->last_hash, hash, SHA1_MAC_LEN);
266 l2->rx_callback(l2->rx_callback_ctx, ll.sll_addr, buf, res);
267 }
268 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
269
270
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)271 struct l2_packet_data * l2_packet_init(
272 const char *ifname, const u8 *own_addr, unsigned short protocol,
273 void (*rx_callback)(void *ctx, const u8 *src_addr,
274 const u8 *buf, size_t len),
275 void *rx_callback_ctx, int l2_hdr)
276 {
277 struct l2_packet_data *l2;
278 struct ifreq ifr;
279 struct sockaddr_ll ll;
280
281 l2 = os_zalloc(sizeof(struct l2_packet_data));
282 if (l2 == NULL)
283 return NULL;
284 os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
285 l2->rx_callback = rx_callback;
286 l2->rx_callback_ctx = rx_callback_ctx;
287 l2->l2_hdr = l2_hdr;
288 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
289 l2->fd_br_rx = -1;
290 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
291
292 l2->fd = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
293 htons(protocol));
294 if (l2->fd < 0) {
295 wpa_printf(MSG_ERROR, "%s: socket(PF_PACKET): %s",
296 __func__, strerror(errno));
297 os_free(l2);
298 return NULL;
299 }
300 os_memset(&ifr, 0, sizeof(ifr));
301 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
302 if (ioctl(l2->fd, SIOCGIFINDEX, &ifr) < 0) {
303 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFINDEX]: %s",
304 __func__, strerror(errno));
305 close(l2->fd);
306 os_free(l2);
307 return NULL;
308 }
309 l2->ifindex = ifr.ifr_ifindex;
310
311 os_memset(&ll, 0, sizeof(ll));
312 ll.sll_family = PF_PACKET;
313 ll.sll_ifindex = ifr.ifr_ifindex;
314 ll.sll_protocol = htons(protocol);
315 if (rx_callback &&
316 bind(l2->fd, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
317 wpa_printf(MSG_ERROR, "%s: bind[PF_PACKET]: %s",
318 __func__, strerror(errno));
319 close(l2->fd);
320 os_free(l2);
321 return NULL;
322 }
323
324 if (ioctl(l2->fd, SIOCGIFHWADDR, &ifr) < 0) {
325 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFHWADDR]: %s",
326 __func__, strerror(errno));
327 close(l2->fd);
328 os_free(l2);
329 return NULL;
330 }
331 os_memcpy(l2->own_addr, ifr.ifr_hwaddr.sa_data, ETH_ALEN);
332
333 if (rx_callback)
334 eloop_register_read_sock(l2->fd, l2_packet_receive, l2, NULL);
335
336 return l2;
337 }
338
339
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)340 struct l2_packet_data * l2_packet_init_bridge(
341 const char *br_ifname, const char *ifname, const u8 *own_addr,
342 unsigned short protocol,
343 void (*rx_callback)(void *ctx, const u8 *src_addr,
344 const u8 *buf, size_t len),
345 void *rx_callback_ctx, int l2_hdr)
346 {
347 struct l2_packet_data *l2;
348 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
349 struct sock_filter ethertype_sock_filter_insns[] = {
350 /* Load ethertype */
351 BPF_STMT(BPF_LD | BPF_H | BPF_ABS, 2 * ETH_ALEN),
352 /* Jump over next statement if ethertype does not match */
353 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, protocol, 0, 1),
354 /* Ethertype match - return all */
355 BPF_STMT(BPF_RET | BPF_K, ~0),
356 /* No match - drop */
357 BPF_STMT(BPF_RET | BPF_K, 0)
358 };
359 const struct sock_fprog ethertype_sock_filter = {
360 .len = ARRAY_SIZE(ethertype_sock_filter_insns),
361 .filter = ethertype_sock_filter_insns,
362 };
363 struct sockaddr_ll ll;
364 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
365
366 l2 = l2_packet_init(br_ifname, own_addr, protocol, rx_callback,
367 rx_callback_ctx, l2_hdr);
368 if (!l2)
369 return NULL;
370
371 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
372 /*
373 * The Linux packet socket behavior has changed over the years and there
374 * is an inconvenient regression in it that breaks RX for a specific
375 * protocol from interfaces in a bridge when that interface is not in
376 * fully operation state (i.e., when in station mode and not completed
377 * authorization). To work around this, register ETH_P_ALL version of
378 * the packet socket bound to the real netdev and use socket filter to
379 * match the ethertype value. This version is less efficient, but
380 * required for functionality with many kernel version. If the main
381 * packet socket is found to be working, this less efficient version
382 * gets closed automatically.
383 */
384
385 l2->fd_br_rx = socket(PF_PACKET, l2_hdr ? SOCK_RAW : SOCK_DGRAM,
386 htons(ETH_P_ALL));
387 if (l2->fd_br_rx < 0) {
388 wpa_printf(MSG_DEBUG, "%s: socket(PF_PACKET-fd_br_rx): %s",
389 __func__, strerror(errno));
390 /* try to continue without the workaround RX socket */
391 return l2;
392 }
393
394 os_memset(&ll, 0, sizeof(ll));
395 ll.sll_family = PF_PACKET;
396 ll.sll_ifindex = if_nametoindex(ifname);
397 ll.sll_protocol = htons(ETH_P_ALL);
398 if (bind(l2->fd_br_rx, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
399 wpa_printf(MSG_DEBUG, "%s: bind[PF_PACKET-fd_br_rx]: %s",
400 __func__, strerror(errno));
401 /* try to continue without the workaround RX socket */
402 close(l2->fd_br_rx);
403 l2->fd_br_rx = -1;
404 return l2;
405 }
406
407 if (setsockopt(l2->fd_br_rx, SOL_SOCKET, SO_ATTACH_FILTER,
408 ðertype_sock_filter, sizeof(struct sock_fprog))) {
409 wpa_printf(MSG_DEBUG,
410 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
411 strerror(errno));
412 /* try to continue without the workaround RX socket */
413 close(l2->fd_br_rx);
414 l2->fd_br_rx = -1;
415 return l2;
416 }
417
418 eloop_register_read_sock(l2->fd_br_rx, l2_packet_receive_br, l2, NULL);
419 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
420
421 return l2;
422 }
423
424
l2_packet_deinit(struct l2_packet_data * l2)425 void l2_packet_deinit(struct l2_packet_data *l2)
426 {
427 if (l2 == NULL)
428 return;
429
430 if (l2->fd >= 0) {
431 eloop_unregister_read_sock(l2->fd);
432 close(l2->fd);
433 }
434
435 #ifndef CONFIG_NO_LINUX_PACKET_SOCKET_WAR
436 if (l2->fd_br_rx >= 0) {
437 eloop_unregister_read_sock(l2->fd_br_rx);
438 close(l2->fd_br_rx);
439 }
440 #endif /* CONFIG_NO_LINUX_PACKET_SOCKET_WAR */
441
442 os_free(l2);
443 }
444
445
l2_packet_get_ip_addr(struct l2_packet_data * l2,char * buf,size_t len)446 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
447 {
448 int s;
449 struct ifreq ifr;
450 struct sockaddr_in *saddr;
451 size_t res;
452
453 s = socket(PF_INET, SOCK_DGRAM, 0);
454 if (s < 0) {
455 wpa_printf(MSG_ERROR, "%s: socket: %s",
456 __func__, strerror(errno));
457 return -1;
458 }
459 os_memset(&ifr, 0, sizeof(ifr));
460 os_strlcpy(ifr.ifr_name, l2->ifname, sizeof(ifr.ifr_name));
461 if (ioctl(s, SIOCGIFADDR, &ifr) < 0) {
462 if (errno != EADDRNOTAVAIL)
463 wpa_printf(MSG_ERROR, "%s: ioctl[SIOCGIFADDR]: %s",
464 __func__, strerror(errno));
465 close(s);
466 return -1;
467 }
468 close(s);
469 saddr = aliasing_hide_typecast(&ifr.ifr_addr, struct sockaddr_in);
470 if (saddr->sin_family != AF_INET)
471 return -1;
472 res = os_strlcpy(buf, inet_ntoa(saddr->sin_addr), len);
473 if (res >= len)
474 return -1;
475 return 0;
476 }
477
478
l2_packet_notify_auth_start(struct l2_packet_data * l2)479 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
480 {
481 }
482
483
l2_packet_set_packet_filter(struct l2_packet_data * l2,enum l2_packet_filter_type type)484 int l2_packet_set_packet_filter(struct l2_packet_data *l2,
485 enum l2_packet_filter_type type)
486 {
487 const struct sock_fprog *sock_filter;
488
489 if (TEST_FAIL())
490 return -1;
491
492 switch (type) {
493 case L2_PACKET_FILTER_DHCP:
494 sock_filter = &dhcp_sock_filter;
495 break;
496 case L2_PACKET_FILTER_NDISC:
497 sock_filter = &ndisc_sock_filter;
498 break;
499 case L2_PACKET_FILTER_PKTTYPE:
500 sock_filter = &pkt_type_sock_filter;
501 break;
502 default:
503 return -1;
504 }
505
506 if (setsockopt(l2->fd, SOL_SOCKET, SO_ATTACH_FILTER,
507 sock_filter, sizeof(struct sock_fprog))) {
508 wpa_printf(MSG_ERROR,
509 "l2_packet_linux: setsockopt(SO_ATTACH_FILTER) failed: %s",
510 strerror(errno));
511 return -1;
512 }
513
514 return 0;
515 }
516
