summaryrefslogtreecommitdiff
path: root/arch/um/drivers/vector_user.c
blob: e2c969b9f7eed5f84656c790ba58e51db79e2c32 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <stdio.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <stddef.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_tun.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <net/ethernet.h>
#include <netinet/ip.h>
#include <netinet/ether.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <sys/wait.h>
#include <sys/uio.h>
#include <linux/virtio_net.h>
#include <netdb.h>
#include <stdlib.h>
#include <os.h>
#include <um_malloc.h>
#include "vector_user.h"

#define ID_GRE 0
#define ID_L2TPV3 1
#define ID_BESS 2
#define ID_MAX 2

#define TOKEN_IFNAME "ifname"

#define TRANS_RAW "raw"
#define TRANS_RAW_LEN strlen(TRANS_RAW)

#define VNET_HDR_FAIL "could not enable vnet headers on fd %d"
#define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s"
#define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i"
#define UNIX_BIND_FAIL "unix_open : could not bind socket err=%i"
#define BPF_ATTACH_FAIL "Failed to attach filter size %d to %d, err %d\n"

#define MAX_UN_LEN 107

/* This is very ugly and brute force lookup, but it is done
 * only once at initialization so not worth doing hashes or
 * anything more intelligent
 */

char *uml_vector_fetch_arg(struct arglist *ifspec, char *token)
{
	int i;

	for (i = 0; i < ifspec->numargs; i++) {
		if (strcmp(ifspec->tokens[i], token) == 0)
			return ifspec->values[i];
	}
	return NULL;

}

struct arglist *uml_parse_vector_ifspec(char *arg)
{
	struct arglist *result;
	int pos, len;
	bool parsing_token = true, next_starts = true;

	if (arg == NULL)
		return NULL;
	result = uml_kmalloc(sizeof(struct arglist), UM_GFP_KERNEL);
	if (result == NULL)
		return NULL;
	result->numargs = 0;
	len = strlen(arg);
	for (pos = 0; pos < len; pos++) {
		if (next_starts) {
			if (parsing_token) {
				result->tokens[result->numargs] = arg + pos;
			} else {
				result->values[result->numargs] = arg + pos;
				result->numargs++;
			}
			next_starts = false;
		}
		if (*(arg + pos) == '=') {
			if (parsing_token)
				parsing_token = false;
			else
				goto cleanup;
			next_starts = true;
			(*(arg + pos)) = '\0';
		}
		if (*(arg + pos) == ',') {
			parsing_token = true;
			next_starts = true;
			(*(arg + pos)) = '\0';
		}
	}
	return result;
cleanup:
	printk(UM_KERN_ERR "vector_setup - Couldn't parse '%s'\n", arg);
	kfree(result);
	return NULL;
}

/*
 * Socket/FD configuration functions. These return an structure
 * of rx and tx descriptors to cover cases where these are not
 * the same (f.e. read via raw socket and write via tap).
 */

#define PATH_NET_TUN "/dev/net/tun"


static int create_tap_fd(char *iface)
{
	struct ifreq ifr;
	int fd = -1;
	int err = -ENOMEM, offload;

	fd = open(PATH_NET_TUN, O_RDWR);
	if (fd < 0) {
		printk(UM_KERN_ERR "uml_tap: failed to open tun device\n");
		goto tap_fd_cleanup;
	}
	memset(&ifr, 0, sizeof(ifr));
	ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);

	err = ioctl(fd, TUNSETIFF, (void *) &ifr);
	if (err != 0) {
		printk(UM_KERN_ERR "uml_tap: failed to select tap interface\n");
		goto tap_fd_cleanup;
	}

	offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
	ioctl(fd, TUNSETOFFLOAD, offload);
	return fd;
tap_fd_cleanup:
	if (fd >= 0)
		os_close_file(fd);
	return err;
}

static int create_raw_fd(char *iface, int flags, int proto)
{
	struct ifreq ifr;
	int fd = -1;
	struct sockaddr_ll sock;
	int err = -ENOMEM;

	fd = socket(AF_PACKET, SOCK_RAW, flags);
	if (fd == -1) {
		err = -errno;
		goto raw_fd_cleanup;
	}
	memset(&ifr, 0, sizeof(ifr));
	strncpy((char *)&ifr.ifr_name, iface, sizeof(ifr.ifr_name) - 1);
	if (ioctl(fd, SIOCGIFINDEX, (void *) &ifr) < 0) {
		err = -errno;
		goto raw_fd_cleanup;
	}

	sock.sll_family = AF_PACKET;
	sock.sll_protocol = htons(proto);
	sock.sll_ifindex = ifr.ifr_ifindex;

	if (bind(fd,
		(struct sockaddr *) &sock, sizeof(struct sockaddr_ll)) < 0) {
		err = -errno;
		goto raw_fd_cleanup;
	}
	return fd;
raw_fd_cleanup:
	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
	if (fd >= 0)
		os_close_file(fd);
	return err;
}

static struct vector_fds *user_init_tap_fds(struct arglist *ifspec)
{
	int fd = -1;
	char *iface;
	struct vector_fds *result = NULL;

	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
	if (iface == NULL) {
		printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
		goto tap_cleanup;
	}

	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
	if (result == NULL) {
		printk(UM_KERN_ERR "uml_tap: failed to allocate file descriptors\n");
		goto tap_cleanup;
	}
	result->rx_fd = -1;
	result->tx_fd = -1;
	result->remote_addr = NULL;
	result->remote_addr_size = 0;

	/* TAP */

	fd = create_tap_fd(iface);
	if (fd < 0) {
		printk(UM_KERN_ERR "uml_tap: failed to create tun interface\n");
		goto tap_cleanup;
	}
	result->tx_fd = fd;
	result->rx_fd = fd;
	return result;
tap_cleanup:
	printk(UM_KERN_ERR "user_init_tap: init failed, error %d", fd);
	if (result != NULL)
		kfree(result);
	return NULL;
}

static struct vector_fds *user_init_hybrid_fds(struct arglist *ifspec)
{
	char *iface;
	struct vector_fds *result = NULL;

	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
	if (iface == NULL) {
		printk(UM_KERN_ERR "uml_tap: failed to parse interface spec\n");
		goto hybrid_cleanup;
	}

	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
	if (result == NULL) {
		printk(UM_KERN_ERR "uml_tap: failed to allocate file descriptors\n");
		goto hybrid_cleanup;
	}
	result->rx_fd = -1;
	result->tx_fd = -1;
	result->remote_addr = NULL;
	result->remote_addr_size = 0;

	/* TAP */

	result->tx_fd = create_tap_fd(iface);
	if (result->tx_fd < 0) {
		printk(UM_KERN_ERR "uml_tap: failed to create tun interface: %i\n", result->tx_fd);
		goto hybrid_cleanup;
	}

	/* RAW */

	result->rx_fd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
	if (result->rx_fd == -1) {
		printk(UM_KERN_ERR
			"uml_tap: failed to create paired raw socket: %i\n", result->rx_fd);
		goto hybrid_cleanup;
	}
	return result;
hybrid_cleanup:
	printk(UM_KERN_ERR "user_init_hybrid: init failed");
	if (result != NULL)
		kfree(result);
	return NULL;
}

static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
{
	int fd = -1;
	int socktype;
	char *src, *dst;
	struct vector_fds *result = NULL;
	struct sockaddr_un *local_addr = NULL, *remote_addr = NULL;

	src = uml_vector_fetch_arg(ifspec, "src");
	dst = uml_vector_fetch_arg(ifspec, "dst");
	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
	if (result == NULL) {
		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
		goto unix_cleanup;
	}
	remote_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
	if (remote_addr == NULL) {
		printk(UM_KERN_ERR "unix open:cannot allocate remote addr");
		goto unix_cleanup;
	}

	switch (id) {
	case ID_BESS:
		socktype = SOCK_SEQPACKET;
		if ((src != NULL) && (strlen(src) <= MAX_UN_LEN)) {
			local_addr = uml_kmalloc(sizeof(struct sockaddr_un), UM_GFP_KERNEL);
			if (local_addr == NULL) {
				printk(UM_KERN_ERR "bess open:cannot allocate local addr");
				goto unix_cleanup;
			}
			local_addr->sun_family = AF_UNIX;
			memcpy(local_addr->sun_path, src, strlen(src) + 1);
		}
		if ((dst == NULL) || (strlen(dst) > MAX_UN_LEN))
			goto unix_cleanup;
		remote_addr->sun_family = AF_UNIX;
		memcpy(remote_addr->sun_path, dst, strlen(dst) + 1);
		break;
	default:
		printk(KERN_ERR "Unsupported unix socket type\n");
		return NULL;
	}

	fd = socket(AF_UNIX, socktype, 0);
	if (fd == -1) {
		printk(UM_KERN_ERR
			"unix open: could not open socket, error = %d",
			-errno
		);
		goto unix_cleanup;
	}
	if (local_addr != NULL) {
		if (bind(fd, (struct sockaddr *) local_addr, sizeof(struct sockaddr_un))) {
			printk(UM_KERN_ERR UNIX_BIND_FAIL, errno);
			goto unix_cleanup;
		}
	}
	switch (id) {
	case ID_BESS:
		if (connect(fd, remote_addr, sizeof(struct sockaddr_un)) < 0) {
			printk(UM_KERN_ERR "bess open:cannot connect to %s %i", remote_addr->sun_path, -errno);
			goto unix_cleanup;
		}
		break;
	}
	result->rx_fd = fd;
	result->tx_fd = fd;
	result->remote_addr_size = sizeof(struct sockaddr_un);
	result->remote_addr = remote_addr;
	return result;
unix_cleanup:
	if (fd >= 0)
		os_close_file(fd);
	if (remote_addr != NULL)
		kfree(remote_addr);
	if (result != NULL)
		kfree(result);
	return NULL;
}

static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
{
	int rxfd = -1, txfd = -1;
	int err = -ENOMEM;
	char *iface;
	struct vector_fds *result = NULL;

	iface = uml_vector_fetch_arg(ifspec, TOKEN_IFNAME);
	if (iface == NULL)
		goto raw_cleanup;

	rxfd = create_raw_fd(iface, ETH_P_ALL, ETH_P_ALL);
	if (rxfd == -1) {
		err = -errno;
		goto raw_cleanup;
	}
	txfd = create_raw_fd(iface, 0, ETH_P_IP); /* Turn off RX on this fd */
	if (txfd == -1) {
		err = -errno;
		goto raw_cleanup;
	}
	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
	if (result != NULL) {
		result->rx_fd = rxfd;
		result->tx_fd = txfd;
		result->remote_addr = NULL;
		result->remote_addr_size = 0;
	}
	return result;
raw_cleanup:
	printk(UM_KERN_ERR "user_init_raw: init failed, error %d", err);
	if (result != NULL)
		kfree(result);
	return NULL;
}


bool uml_raw_enable_qdisc_bypass(int fd)
{
	int optval = 1;

	if (setsockopt(fd,
		SOL_PACKET, PACKET_QDISC_BYPASS,
		&optval, sizeof(optval)) != 0) {
		return false;
	}
	return true;
}

bool uml_raw_enable_vnet_headers(int fd)
{
	int optval = 1;

	if (setsockopt(fd,
		SOL_PACKET, PACKET_VNET_HDR,
		&optval, sizeof(optval)) != 0) {
		printk(UM_KERN_INFO VNET_HDR_FAIL, fd);
		return false;
	}
	return true;
}
bool uml_tap_enable_vnet_headers(int fd)
{
	unsigned int features;
	int len = sizeof(struct virtio_net_hdr);

	if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
		printk(UM_KERN_INFO TUN_GET_F_FAIL, strerror(errno));
		return false;
	}
	if ((features & IFF_VNET_HDR) == 0) {
		printk(UM_KERN_INFO "tapraw: No VNET HEADER support");
		return false;
	}
	ioctl(fd, TUNSETVNETHDRSZ, &len);
	return true;
}

static struct vector_fds *user_init_socket_fds(struct arglist *ifspec, int id)
{
	int err = -ENOMEM;
	int fd = -1, gairet;
	struct addrinfo srchints;
	struct addrinfo dsthints;
	bool v6, udp;
	char *value;
	char *src, *dst, *srcport, *dstport;
	struct addrinfo *gairesult = NULL;
	struct vector_fds *result = NULL;


	value = uml_vector_fetch_arg(ifspec, "v6");
	v6 = false;
	udp = false;
	if (value != NULL) {
		if (strtol((const char *) value, NULL, 10) > 0)
			v6 = true;
	}

	value = uml_vector_fetch_arg(ifspec, "udp");
	if (value != NULL) {
		if (strtol((const char *) value, NULL, 10) > 0)
			udp = true;
	}
	src = uml_vector_fetch_arg(ifspec, "src");
	dst = uml_vector_fetch_arg(ifspec, "dst");
	srcport = uml_vector_fetch_arg(ifspec, "srcport");
	dstport = uml_vector_fetch_arg(ifspec, "dstport");

	memset(&dsthints, 0, sizeof(dsthints));

	if (v6)
		dsthints.ai_family = AF_INET6;
	else
		dsthints.ai_family = AF_INET;

	switch (id) {
	case ID_GRE:
		dsthints.ai_socktype = SOCK_RAW;
		dsthints.ai_protocol = IPPROTO_GRE;
		break;
	case ID_L2TPV3:
		if (udp) {
			dsthints.ai_socktype = SOCK_DGRAM;
			dsthints.ai_protocol = 0;
		} else {
			dsthints.ai_socktype = SOCK_RAW;
			dsthints.ai_protocol = IPPROTO_L2TP;
		}
		break;
	default:
		printk(KERN_ERR "Unsupported socket type\n");
		return NULL;
	}
	memcpy(&srchints, &dsthints, sizeof(struct addrinfo));

	gairet = getaddrinfo(src, srcport, &dsthints, &gairesult);
	if ((gairet != 0) || (gairesult == NULL)) {
		printk(UM_KERN_ERR
			"socket_open : could not resolve src, error = %s",
			gai_strerror(gairet)
		);
		return NULL;
	}
	fd = socket(gairesult->ai_family,
		gairesult->ai_socktype, gairesult->ai_protocol);
	if (fd == -1) {
		printk(UM_KERN_ERR
			"socket_open : could not open socket, error = %d",
			-errno
		);
		goto cleanup;
	}
	if (bind(fd,
		(struct sockaddr *) gairesult->ai_addr,
		gairesult->ai_addrlen)) {
		printk(UM_KERN_ERR L2TPV3_BIND_FAIL, errno);
		goto cleanup;
	}

	if (gairesult != NULL)
		freeaddrinfo(gairesult);

	gairesult = NULL;

	gairet = getaddrinfo(dst, dstport, &dsthints, &gairesult);
	if ((gairet != 0) || (gairesult == NULL)) {
		printk(UM_KERN_ERR
			"socket_open : could not resolve dst, error = %s",
			gai_strerror(gairet)
		);
		return NULL;
	}

	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
	if (result != NULL) {
		result->rx_fd = fd;
		result->tx_fd = fd;
		result->remote_addr = uml_kmalloc(
			gairesult->ai_addrlen, UM_GFP_KERNEL);
		if (result->remote_addr == NULL)
			goto cleanup;
		result->remote_addr_size = gairesult->ai_addrlen;
		memcpy(
			result->remote_addr,
			gairesult->ai_addr,
			gairesult->ai_addrlen
		);
	}
	freeaddrinfo(gairesult);
	return result;
cleanup:
	if (gairesult != NULL)
		freeaddrinfo(gairesult);
	printk(UM_KERN_ERR "user_init_socket: init failed, error %d", err);
	if (fd >= 0)
		os_close_file(fd);
	if (result != NULL) {
		kfree(result->remote_addr);
		kfree(result);
	}
	return NULL;
}

struct vector_fds *uml_vector_user_open(
	int unit,
	struct arglist *parsed
)
{
	char *transport;

	if (parsed == NULL) {
		printk(UM_KERN_ERR "no parsed config for unit %d\n", unit);
		return NULL;
	}
	transport = uml_vector_fetch_arg(parsed, "transport");
	if (transport == NULL) {
		printk(UM_KERN_ERR "missing transport for unit %d\n", unit);
		return NULL;
	}
	if (strncmp(transport, TRANS_RAW, TRANS_RAW_LEN) == 0)
		return user_init_raw_fds(parsed);
	if (strncmp(transport, TRANS_HYBRID, TRANS_HYBRID_LEN) == 0)
		return user_init_hybrid_fds(parsed);
	if (strncmp(transport, TRANS_TAP, TRANS_TAP_LEN) == 0)
		return user_init_tap_fds(parsed);
	if (strncmp(transport, TRANS_GRE, TRANS_GRE_LEN) == 0)
		return user_init_socket_fds(parsed, ID_GRE);
	if (strncmp(transport, TRANS_L2TPV3, TRANS_L2TPV3_LEN) == 0)
		return user_init_socket_fds(parsed, ID_L2TPV3);
	if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
		return user_init_unix_fds(parsed, ID_BESS);
	return NULL;
}


int uml_vector_sendmsg(int fd, void *hdr, int flags)
{
	int n;

	CATCH_EINTR(n = sendmsg(fd, (struct msghdr *) hdr,  flags));
	if ((n < 0) && (errno == EAGAIN))
		return 0;
	if (n >= 0)
		return n;
	else
		return -errno;
}

int uml_vector_recvmsg(int fd, void *hdr, int flags)
{
	int n;
	struct msghdr *msg = (struct msghdr *) hdr;

	CATCH_EINTR(n = readv(fd, msg->msg_iov, msg->msg_iovlen));
	if ((n < 0) && (errno == EAGAIN))
		return 0;
	if (n >= 0)
		return n;
	else
		return -errno;
}

int uml_vector_writev(int fd, void *hdr, int iovcount)
{
	int n;

	CATCH_EINTR(n = writev(fd, (struct iovec *) hdr,  iovcount));
	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
		return 0;
	if (n >= 0)
		return n;
	else
		return -errno;
}

int uml_vector_sendmmsg(
	int fd,
	void *msgvec,
	unsigned int vlen,
	unsigned int flags)
{
	int n;

	CATCH_EINTR(n = sendmmsg(fd, (struct mmsghdr *) msgvec, vlen, flags));
	if ((n < 0) && ((errno == EAGAIN) || (errno == ENOBUFS)))
		return 0;
	if (n >= 0)
		return n;
	else
		return -errno;
}

int uml_vector_recvmmsg(
	int fd,
	void *msgvec,
	unsigned int vlen,
	unsigned int flags)
{
	int n;

	CATCH_EINTR(
		n = recvmmsg(fd, (struct mmsghdr *) msgvec, vlen, flags, 0));
	if ((n < 0) && (errno == EAGAIN))
		return 0;
	if (n >= 0)
		return n;
	else
		return -errno;
}
int uml_vector_attach_bpf(int fd, void *bpf, int bpf_len)
{
	int err = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, bpf, bpf_len);

	if (err < 0)
		printk(KERN_ERR BPF_ATTACH_FAIL, bpf_len, fd, -errno);
	return err;
}

#define DEFAULT_BPF_LEN 6

void *uml_vector_default_bpf(int fd, void *mac)
{
	struct sock_filter *bpf;
	uint32_t *mac1 = (uint32_t *)(mac + 2);
	uint16_t *mac2 = (uint16_t *) mac;
	struct sock_fprog bpf_prog = {
		.len = 6,
		.filter = NULL,
	};

	bpf = uml_kmalloc(
		sizeof(struct sock_filter) * DEFAULT_BPF_LEN, UM_GFP_KERNEL);
	if (bpf != NULL) {
		bpf_prog.filter = bpf;
		/* ld	[8] */
		bpf[0] = (struct sock_filter){ 0x20, 0, 0, 0x00000008 };
		/* jeq	#0xMAC[2-6] jt 2 jf 5*/
		bpf[1] = (struct sock_filter){ 0x15, 0, 3, ntohl(*mac1)};
		/* ldh	[6] */
		bpf[2] = (struct sock_filter){ 0x28, 0, 0, 0x00000006 };
		/* jeq	#0xMAC[0-1] jt 4 jf 5 */
		bpf[3] = (struct sock_filter){ 0x15, 0, 1, ntohs(*mac2)};
		/* ret	#0 */
		bpf[4] = (struct sock_filter){ 0x6, 0, 0, 0x00000000 };
		/* ret	#0x40000 */
		bpf[5] = (struct sock_filter){ 0x6, 0, 0, 0x00040000 };
		if (uml_vector_attach_bpf(
			fd, &bpf_prog, sizeof(struct sock_fprog)) < 0) {
			kfree(bpf);
			bpf = NULL;
		}
	}
	return bpf;
}