xref: /openbmc/linux/arch/um/drivers/vector_user.c (revision de528723)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4  */
5 
6 #include <stdio.h>
7 #include <unistd.h>
8 #include <stdarg.h>
9 #include <errno.h>
10 #include <stddef.h>
11 #include <string.h>
12 #include <sys/ioctl.h>
13 #include <net/if.h>
14 #include <linux/if_tun.h>
15 #include <arpa/inet.h>
16 #include <sys/types.h>
17 #include <sys/stat.h>
18 #include <fcntl.h>
19 #include <sys/socket.h>
20 #include <sys/un.h>
21 #include <net/ethernet.h>
22 #include <netinet/ip.h>
23 #include <netinet/ether.h>
24 #include <linux/if_ether.h>
25 #include <linux/if_packet.h>
26 #include <sys/wait.h>
27 #include <sys/uio.h>
28 #include <linux/virtio_net.h>
29 #include <netdb.h>
30 #include <stdlib.h>
31 #include <os.h>
32 #include <um_malloc.h>
33 #include "vector_user.h"
34 
35 #define ID_GRE 0
36 #define ID_L2TPV3 1
37 #define ID_BESS 2
38 #define ID_MAX 2
39 
40 #define TOKEN_IFNAME "ifname"
41 
42 #define TRANS_RAW "raw"
43 #define TRANS_RAW_LEN strlen(TRANS_RAW)
44 
45 #define VNET_HDR_FAIL "could not enable vnet headers on fd %d"
46 #define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s"
47 #define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i"
48 #define UNIX_BIND_FAIL "unix_open : could not bind socket err=%i"
49 #define BPF_ATTACH_FAIL "Failed to attach filter size %d to %d, err %d\n"
50 
51 #define MAX_UN_LEN 107
52 
53 /* This is very ugly and brute force lookup, but it is done
54  * only once at initialization so not worth doing hashes or
55  * anything more intelligent
56  */
57 
58 char *uml_vector_fetch_arg(struct arglist *ifspec, char *token)
59 {
60 	int i;
61 
62 	for (i = 0; i < ifspec->numargs; i++) {
63 		if (strcmp(ifspec->tokens[i], token) == 0)
64 			return ifspec->values[i];
65 	}
66 	return NULL;
67 
68 }
69 
70 struct arglist *uml_parse_vector_ifspec(char *arg)
71 {
72 	struct arglist *result;
73 	int pos, len;
74 	bool parsing_token = true, next_starts = true;
75 
76 	if (arg == NULL)
77 		return NULL;
78 	result = uml_kmalloc(sizeof(struct arglist), UM_GFP_KERNEL);
79 	if (result == NULL)
80 		return NULL;
81 	result->numargs = 0;
82 	len = strlen(arg);
83 	for (pos = 0; pos < len; pos++) {
84 		if (next_starts) {
85 			if (parsing_token) {
86 				result->tokens[result->numargs] = arg + pos;
87 			} else {
88 				result->values[result->numargs] = arg + pos;
89 				result->numargs++;
90 			}
91 			next_starts = false;
92 		}
93 		if (*(arg + pos) == '=') {
94 			if (parsing_token)
95 				parsing_token = false;
96 			else
97 				goto cleanup;
98 			next_starts = true;
99 			(*(arg + pos)) = '\0';
100 		}
101 		if (*(arg + pos) == ',') {
102 			parsing_token = true;
103 			next_starts = true;
104 			(*(arg + pos)) = '\0';
105 		}
106 	}
107 	return result;
108 cleanup:
109 	printk(UM_KERN_ERR "vector_setup - Couldn't parse '%s'\n", arg);
110 	kfree(result);
111 	return NULL;
112 }
113 
114 /*
115  * Socket/FD configuration functions. These return an structure
116  * of rx and tx descriptors to cover cases where these are not
117  * the same (f.e. read via raw socket and write via tap).
118  */
119 
120 #define PATH_NET_TUN "/dev/net/tun"
121 
122 
123 static int create_tap_fd(char *iface)
124 {
125 	struct ifreq ifr;
126 	int fd = -1;
127 	int err = -ENOMEM, offload;
128 
129 	fd = open(PATH_NET_TUN, O_RDWR);
130 	if (fd < 0) {
131 		printk(UM_KERN_ERR "uml_tap: failed to open tun device\n");
132 		goto tap_fd_cleanup;
133 	}
134 	memset(&ifr, 0, sizeof(ifr));
135 	ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
136 	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
137 
138 	err = ioctl(fd, TUNSETIFF, (void *) &ifr);
139 	if (err != 0) {
140 		printk(UM_KERN_ERR "uml_tap: failed to select tap interface\n");
141 		goto tap_fd_cleanup;
142 	}
143 
144 	offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
145 	ioctl(fd, TUNSETOFFLOAD, offload);
146 	return fd;
147 tap_fd_cleanup:
148 	if (fd >= 0)
149 		os_close_file(fd);
150 	return err;
151 }
152 
153 static int create_raw_fd(char *iface, int flags, int proto)
154 {
155 	struct ifreq ifr;
156 	int fd = -1;
157 	struct sockaddr_ll sock;
158 	int err = -ENOMEM;
159 
160 	fd = socket(AF_PACKET, SOCK_RAW, flags);
161 	if (fd == -1) {
162 		err = -errno;
163 		goto raw_fd_cleanup;
164 	}
165 	memset(&ifr, 0, sizeof(ifr));
166 	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
167 	if (ioctl(fd, SIOCGIFINDEX, (void *) &ifr) < 0) {
168 		err = -errno;
169 		goto raw_fd_cleanup;
170 	}
171 
172 	sock.sll_family = AF_PACKET;
173 	sock.sll_protocol = htons(proto);
174 	sock.sll_ifindex = ifr.ifr_ifindex;
175 
176 	if (bind(fd,
177 		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
178 		err = -errno;
179 		goto raw_fd_cleanup;
180 	}
181 	return fd;
182 raw_fd_cleanup:
183 	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
184 	if (fd >= 0)
185 		os_close_file(fd);
186 	return err;
187 }
188 
189 static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
190 {
191 	int fd = -1;
192 	char *iface;
193 	struct vector_fds *result = NULL;
194 
195 	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
196 	if (iface == NULL) {
197 		printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
198 		goto tap_cleanup;
199 	}
200 
201 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
202 	if (result == NULL) {
203 		printk(UM_KERN_ERR "uml_tap: failed to allocate file descriptors\n");
204 		goto tap_cleanup;
205 	}
206 	result->rx_fd = -1;
207 	result->tx_fd = -1;
208 	result->remote_addr = NULL;
209 	result->remote_addr_size = 0;
210 
211 	/* TAP */
212 
213 	fd = create_tap_fd(iface);
214 	if (fd < 0) {
215 		printk(UM_KERN_ERR "uml_tap: failed to create tun interface\n");
216 		goto tap_cleanup;
217 	}
218 	result->tx_fd = fd;
219 	result->rx_fd = fd;
220 	return result;
221 tap_cleanup:
222 	printk(UM_KERN_ERR "user_init_tap: init failed, error %d", fd);
223 	if (result != NULL)
224 		kfree(result);
225 	return NULL;
226 }
227 
228 static struct vector_fds *user_init_hybrid_fds(struct arglist *ifspec)
229 {
230 	char *iface;
231 	struct vector_fds *result = NULL;
232 
233 	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
234 	if (iface == NULL) {
235 		printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
236 		goto hybrid_cleanup;
237 	}
238 
239 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
240 	if (result == NULL) {
241 		printk(UM_KERN_ERR "uml_tap: failed to allocate file descriptors\n");
242 		goto hybrid_cleanup;
243 	}
244 	result->rx_fd = -1;
245 	result->tx_fd = -1;
246 	result->remote_addr = NULL;
247 	result->remote_addr_size = 0;
248 
249 	/* TAP */
250 
251 	result->tx_fd = create_tap_fd(iface);
252 	if (result->tx_fd < 0) {
253 		printk(UM_KERN_ERR "uml_tap: failed to create tun interface: %i\n", result->tx_fd);
254 		goto hybrid_cleanup;
255 	}
256 
257 	/* RAW */
258 
259 	result->rx_fd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
260 	if (result->rx_fd == -1) {
261 		printk(UM_KERN_ERR
262 			"uml_tap: failed to create paired raw socket: %i\n", result->rx_fd);
263 		goto hybrid_cleanup;
264 	}
265 	return result;
266 hybrid_cleanup:
267 	printk(UM_KERN_ERR "user_init_hybrid: init failed");
268 	if (result != NULL)
269 		kfree(result);
270 	return NULL;
271 }
272 
273 static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
274 {
275 	int fd = -1;
276 	int socktype;
277 	char *src, *dst;
278 	struct vector_fds *result = NULL;
279 	struct sockaddr_un *local_addr = NULL, *remote_addr = NULL;
280 
281 	src = uml_vector_fetch_arg(ifspec, "src");
282 	dst = uml_vector_fetch_arg(ifspec, "dst");
283 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
284 	if (result == NULL) {
285 		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
286 		goto unix_cleanup;
287 	}
288 	remote_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
289 	if (remote_addr == NULL) {
290 		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
291 		goto unix_cleanup;
292 	}
293 
294 	switch (id) {
295 	case ID_BESS:
296 		socktype = SOCK_SEQPACKET;
297 		if ((src != NULL) && (strlen(src) <= MAX_UN_LEN)) {
298 			local_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
299 			if (local_addr == NULL) {
300 				printk(UM_KERN_ERR "bess open:cannot allocate local addr");
301 				goto unix_cleanup;
302 			}
303 			local_addr->sun_family = AF_UNIX;
304 			memcpy(local_addr->sun_path, src, strlen(src) + 1);
305 		}
306 		if ((dst == NULL) || (strlen(dst) > MAX_UN_LEN))
307 			goto unix_cleanup;
308 		remote_addr->sun_family = AF_UNIX;
309 		memcpy(remote_addr->sun_path, dst, strlen(dst) + 1);
310 		break;
311 	default:
312 		printk(KERN_ERR "Unsupported unix socket type\n");
313 		return NULL;
314 	}
315 
316 	fd = socket(AF_UNIX, socktype, 0);
317 	if (fd == -1) {
318 		printk(UM_KERN_ERR
319 			"unix open: could not open socket, error = %d",
320 			-errno
321 		);
322 		goto unix_cleanup;
323 	}
324 	if (local_addr != NULL) {
325 		if (bind(fd, (struct sockaddr *) local_addr, sizeof(struct sockaddr_un))) {
326 			printk(UM_KERN_ERR UNIX_BIND_FAIL, errno);
327 			goto unix_cleanup;
328 		}
329 	}
330 	switch (id) {
331 	case ID_BESS:
332 		if (connect(fd, remote_addr, sizeof(struct sockaddr_un)) < 0) {
333 			printk(UM_KERN_ERR "bess open:cannot connect to %s %i", remote_addr->sun_path, -errno);
334 			goto unix_cleanup;
335 		}
336 		break;
337 	}
338 	result->rx_fd = fd;
339 	result->tx_fd = fd;
340 	result->remote_addr_size = sizeof(struct sockaddr_un);
341 	result->remote_addr = remote_addr;
342 	return result;
343 unix_cleanup:
344 	if (fd >= 0)
345 		os_close_file(fd);
346 	if (remote_addr != NULL)
347 		kfree(remote_addr);
348 	if (result != NULL)
349 		kfree(result);
350 	return NULL;
351 }
352 
353 static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
354 {
355 	int rxfd = -1, txfd = -1;
356 	int err = -ENOMEM;
357 	char *iface;
358 	struct vector_fds *result = NULL;
359 
360 	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
361 	if (iface == NULL)
362 		goto raw_cleanup;
363 
364 	rxfd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
365 	if (rxfd == -1) {
366 		err = -errno;
367 		goto raw_cleanup;
368 	}
369 	txfd = create_raw_fd(iface, 0, ETH_P_IP); /* Turn off RX on this fd */
370 	if (txfd == -1) {
371 		err = -errno;
372 		goto raw_cleanup;
373 	}
374 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
375 	if (result != NULL) {
376 		result->rx_fd = rxfd;
377 		result->tx_fd = txfd;
378 		result->remote_addr = NULL;
379 		result->remote_addr_size = 0;
380 	}
381 	return result;
382 raw_cleanup:
383 	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
384 	if (result != NULL)
385 		kfree(result);
386 	return NULL;
387 }
388 
389 
390 bool uml_raw_enable_qdisc_bypass(int fd)
391 {
392 	int optval = 1;
393 
394 	if (setsockopt(fd,
395 		SOL_PACKET, PACKET_QDISC_BYPASS,
396 		&optval, sizeof(optval)) != 0) {
397 		return false;
398 	}
399 	return true;
400 }
401 
402 bool uml_raw_enable_vnet_headers(int fd)
403 {
404 	int optval = 1;
405 
406 	if (setsockopt(fd,
407 		SOL_PACKET, PACKET_VNET_HDR,
408 		&optval, sizeof(optval)) != 0) {
409 		printk(UM_KERN_INFO VNET_HDR_FAIL, fd);
410 		return false;
411 	}
412 	return true;
413 }
414 bool uml_tap_enable_vnet_headers(int fd)
415 {
416 	unsigned int features;
417 	int len = sizeof(struct virtio_net_hdr);
418 
419 	if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
420 		printk(UM_KERN_INFO TUN_GET_F_FAIL, strerror(errno));
421 		return false;
422 	}
423 	if ((features & IFF_VNET_HDR) == 0) {
424 		printk(UM_KERN_INFO "tapraw: No VNET HEADER support");
425 		return false;
426 	}
427 	ioctl(fd, TUNSETVNETHDRSZ, &len);
428 	return true;
429 }
430 
431 static struct vector_fds *user_init_socket_fds(struct arglist *ifspec, int id)
432 {
433 	int err = -ENOMEM;
434 	int fd = -1, gairet;
435 	struct addrinfo srchints;
436 	struct addrinfo dsthints;
437 	bool v6, udp;
438 	char *value;
439 	char *src, *dst, *srcport, *dstport;
440 	struct addrinfo *gairesult = NULL;
441 	struct vector_fds *result = NULL;
442 
443 
444 	value = uml_vector_fetch_arg(ifspec, "v6");
445 	v6 = false;
446 	udp = false;
447 	if (value != NULL) {
448 		if (strtol((const char *) value, NULL, 10) > 0)
449 			v6 = true;
450 	}
451 
452 	value = uml_vector_fetch_arg(ifspec, "udp");
453 	if (value != NULL) {
454 		if (strtol((const char *) value, NULL, 10) > 0)
455 			udp = true;
456 	}
457 	src = uml_vector_fetch_arg(ifspec, "src");
458 	dst = uml_vector_fetch_arg(ifspec, "dst");
459 	srcport = uml_vector_fetch_arg(ifspec, "srcport");
460 	dstport = uml_vector_fetch_arg(ifspec, "dstport");
461 
462 	memset(&dsthints, 0, sizeof(dsthints));
463 
464 	if (v6)
465 		dsthints.ai_family = AF_INET6;
466 	else
467 		dsthints.ai_family = AF_INET;
468 
469 	switch (id) {
470 	case ID_GRE:
471 		dsthints.ai_socktype = SOCK_RAW;
472 		dsthints.ai_protocol = IPPROTO_GRE;
473 		break;
474 	case ID_L2TPV3:
475 		if (udp) {
476 			dsthints.ai_socktype = SOCK_DGRAM;
477 			dsthints.ai_protocol = 0;
478 		} else {
479 			dsthints.ai_socktype = SOCK_RAW;
480 			dsthints.ai_protocol = IPPROTO_L2TP;
481 		}
482 		break;
483 	default:
484 		printk(KERN_ERR "Unsupported socket type\n");
485 		return NULL;
486 	}
487 	memcpy(&srchints, &dsthints, sizeof(struct addrinfo));
488 
489 	gairet = getaddrinfo(src, srcport, &dsthints, &gairesult);
490 	if ((gairet != 0) || (gairesult == NULL)) {
491 		printk(UM_KERN_ERR
492 			"socket_open : could not resolve src, error = %s",
493 			gai_strerror(gairet)
494 		);
495 		return NULL;
496 	}
497 	fd = socket(gairesult->ai_family,
498 		gairesult->ai_socktype, gairesult->ai_protocol);
499 	if (fd == -1) {
500 		printk(UM_KERN_ERR
501 			"socket_open : could not open socket, error = %d",
502 			-errno
503 		);
504 		goto cleanup;
505 	}
506 	if (bind(fd,
507 		(struct sockaddr *) gairesult->ai_addr,
508 		gairesult->ai_addrlen)) {
509 		printk(UM_KERN_ERR L2TPV3_BIND_FAIL, errno);
510 		goto cleanup;
511 	}
512 
513 	if (gairesult != NULL)
514 		freeaddrinfo(gairesult);
515 
516 	gairesult = NULL;
517 
518 	gairet = getaddrinfo(dst, dstport, &dsthints, &gairesult);
519 	if ((gairet != 0) || (gairesult == NULL)) {
520 		printk(UM_KERN_ERR
521 			"socket_open : could not resolve dst, error = %s",
522 			gai_strerror(gairet)
523 		);
524 		return NULL;
525 	}
526 
527 	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
528 	if (result != NULL) {
529 		result->rx_fd = fd;
530 		result->tx_fd = fd;
531 		result->remote_addr = uml_kmalloc(
532 			gairesult->ai_addrlen, UM_GFP_KERNEL);
533 		if (result->remote_addr == NULL)
534 			goto cleanup;
535 		result->remote_addr_size = gairesult->ai_addrlen;
536 		memcpy(
537 			result->remote_addr,
538 			gairesult->ai_addr,
539 			gairesult->ai_addrlen
540 		);
541 	}
542 	freeaddrinfo(gairesult);
543 	return result;
544 cleanup:
545 	if (gairesult != NULL)
546 		freeaddrinfo(gairesult);
547 	printk(UM_KERN_ERR "user_init_socket: init failed, error %d", err);
548 	if (fd >= 0)
549 		os_close_file(fd);
550 	if (result != NULL) {
551 		kfree(result->remote_addr);
552 		kfree(result);
553 	}
554 	return NULL;
555 }
556 
557 struct vector_fds *uml_vector_user_open(
558 	int unit,
559 	struct arglist *parsed
560 )
561 {
562 	char *transport;
563 
564 	if (parsed == NULL) {
565 		printk(UM_KERN_ERR "no parsed config for unit %d\n", unit);
566 		return NULL;
567 	}
568 	transport = uml_vector_fetch_arg(parsed, "transport");
569 	if (transport == NULL) {
570 		printk(UM_KERN_ERR "missing transport for unit %d\n", unit);
571 		return NULL;
572 	}
573 	if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
574 		return user_init_raw_fds(parsed);
575 	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
576 		return user_init_hybrid_fds(parsed);
577 	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
578 		return user_init_tap_fds(parsed);
579 	if (strncmp(transport, TRANS_GRE, TRANS_GRE_LEN) == 0)
580 		return user_init_socket_fds(parsed, ID_GRE);
581 	if (strncmp(transport, TRANS_L2TPV3, TRANS_L2TPV3_LEN) == 0)
582 		return user_init_socket_fds(parsed, ID_L2TPV3);
583 	if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
584 		return user_init_unix_fds(parsed, ID_BESS);
585 	return NULL;
586 }
587 
588 
589 int uml_vector_sendmsg(int fd, void *hdr, int flags)
590 {
591 	int n;
592 
593 	CATCH_EINTR(n = sendmsg(fd, (struct msghdr *) hdr,  flags));
594 	if ((n < 0) && (errno == EAGAIN))
595 		return 0;
596 	if (n >= 0)
597 		return n;
598 	else
599 		return -errno;
600 }
601 
602 int uml_vector_recvmsg(int fd, void *hdr, int flags)
603 {
604 	int n;
605 	struct msghdr *msg = (struct msghdr *) hdr;
606 
607 	CATCH_EINTR(n = readv(fd, msg->msg_iov, msg->msg_iovlen));
608 	if ((n < 0) && (errno == EAGAIN))
609 		return 0;
610 	if (n >= 0)
611 		return n;
612 	else
613 		return -errno;
614 }
615 
616 int uml_vector_writev(int fd, void *hdr, int iovcount)
617 {
618 	int n;
619 
620 	CATCH_EINTR(n = writev(fd, (struct iovec *) hdr,  iovcount));
621 	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
622 		return 0;
623 	if (n >= 0)
624 		return n;
625 	else
626 		return -errno;
627 }
628 
629 int uml_vector_sendmmsg(
630 	int fd,
631 	void *msgvec,
632 	unsigned int vlen,
633 	unsigned int flags)
634 {
635 	int n;
636 
637 	CATCH_EINTR(n = sendmmsg(fd, (struct mmsghdr *) msgvec, vlen, flags));
638 	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
639 		return 0;
640 	if (n >= 0)
641 		return n;
642 	else
643 		return -errno;
644 }
645 
646 int uml_vector_recvmmsg(
647 	int fd,
648 	void *msgvec,
649 	unsigned int vlen,
650 	unsigned int flags)
651 {
652 	int n;
653 
654 	CATCH_EINTR(
655 		n = recvmmsg(fd, (struct mmsghdr *) msgvec, vlen, flags, 0));
656 	if ((n < 0) && (errno == EAGAIN))
657 		return 0;
658 	if (n >= 0)
659 		return n;
660 	else
661 		return -errno;
662 }
663 int uml_vector_attach_bpf(int fd, void *bpf, int bpf_len)
664 {
665 	int err = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, bpf, bpf_len);
666 
667 	if (err < 0)
668 		printk(KERN_ERR BPF_ATTACH_FAIL, bpf_len, fd, -errno);
669 	return err;
670 }
671 
672 #define DEFAULT_BPF_LEN 6
673 
674 void *uml_vector_default_bpf(int fd, void *mac)
675 {
676 	struct sock_filter *bpf;
677 	uint32_t *mac1 = (uint32_t *)(mac + 2);
678 	uint16_t *mac2 = (uint16_t *) mac;
679 	struct sock_fprog bpf_prog = {
680 		.len = 6,
681 		.filter = NULL,
682 	};
683 
684 	bpf = uml_kmalloc(
685 		sizeof(struct sock_filter) * DEFAULT_BPF_LEN, UM_GFP_KERNEL);
686 	if (bpf != NULL) {
687 		bpf_prog.filter = bpf;
688 		/* ld	[8] */
689 		bpf[0] = (struct sock_filter){ 0x20, 0, 0, 0x00000008 };
690 		/* jeq	#0xMAC[2-6] jt 2 jf 5*/
691 		bpf[1] = (struct sock_filter){ 0x15, 0, 3, ntohl(*mac1)};
692 		/* ldh	[6] */
693 		bpf[2] = (struct sock_filter){ 0x28, 0, 0, 0x00000006 };
694 		/* jeq	#0xMAC[0-1] jt 4 jf 5 */
695 		bpf[3] = (struct sock_filter){ 0x15, 0, 1, ntohs(*mac2)};
696 		/* ret	#0 */
697 		bpf[4] = (struct sock_filter){ 0x6, 0, 0, 0x00000000 };
698 		/* ret	#0x40000 */
699 		bpf[5] = (struct sock_filter){ 0x6, 0, 0, 0x00040000 };
700 		if (uml_vector_attach_bpf(
701 			fd, &bpf_prog, sizeof(struct sock_fprog)) < 0) {
702 			kfree(bpf);
703 			bpf = NULL;
704 		}
705 	}
706 	return bpf;
707 }
708 
709