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