xref: /freebsd/sys/compat/linux/linux.c (revision c9539b89010900499a200cdd6c0265ea5d950875)
1 /*-
2  * Copyright (c) 2015 Dmitry Chagin <dchagin@FreeBSD.org>
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23  * SUCH DAMAGE.
24  */
25 
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
28 
29 #include "opt_inet6.h"
30 
31 #include <sys/param.h>
32 #include <sys/conf.h>
33 #include <sys/ctype.h>
34 #include <sys/file.h>
35 #include <sys/filedesc.h>
36 #include <sys/jail.h>
37 #include <sys/lock.h>
38 #include <sys/malloc.h>
39 #include <sys/poll.h>
40 #include <sys/proc.h>
41 #include <sys/signalvar.h>
42 #include <sys/socket.h>
43 #include <sys/socketvar.h>
44 
45 #include <net/if.h>
46 #include <net/if_var.h>
47 #include <net/if_dl.h>
48 #include <net/if_types.h>
49 #include <netlink/netlink.h>
50 
51 #include <sys/un.h>
52 #include <netinet/in.h>
53 
54 #include <compat/linux/linux.h>
55 #include <compat/linux/linux_common.h>
56 #include <compat/linux/linux_mib.h>
57 #include <compat/linux/linux_util.h>
58 
59 CTASSERT(LINUX_IFNAMSIZ == IFNAMSIZ);
60 
61 static bool use_real_ifnames = false;
62 SYSCTL_BOOL(_compat_linux, OID_AUTO, use_real_ifnames, CTLFLAG_RWTUN,
63     &use_real_ifnames, 0,
64     "Use FreeBSD interface names instead of generating ethN aliases");
65 
66 static int bsd_to_linux_sigtbl[LINUX_SIGTBLSZ] = {
67 	LINUX_SIGHUP,	/* SIGHUP */
68 	LINUX_SIGINT,	/* SIGINT */
69 	LINUX_SIGQUIT,	/* SIGQUIT */
70 	LINUX_SIGILL,	/* SIGILL */
71 	LINUX_SIGTRAP,	/* SIGTRAP */
72 	LINUX_SIGABRT,	/* SIGABRT */
73 	0,		/* SIGEMT */
74 	LINUX_SIGFPE,	/* SIGFPE */
75 	LINUX_SIGKILL,	/* SIGKILL */
76 	LINUX_SIGBUS,	/* SIGBUS */
77 	LINUX_SIGSEGV,	/* SIGSEGV */
78 	LINUX_SIGSYS,	/* SIGSYS */
79 	LINUX_SIGPIPE,	/* SIGPIPE */
80 	LINUX_SIGALRM,	/* SIGALRM */
81 	LINUX_SIGTERM,	/* SIGTERM */
82 	LINUX_SIGURG,	/* SIGURG */
83 	LINUX_SIGSTOP,	/* SIGSTOP */
84 	LINUX_SIGTSTP,	/* SIGTSTP */
85 	LINUX_SIGCONT,	/* SIGCONT */
86 	LINUX_SIGCHLD,	/* SIGCHLD */
87 	LINUX_SIGTTIN,	/* SIGTTIN */
88 	LINUX_SIGTTOU,	/* SIGTTOU */
89 	LINUX_SIGIO,	/* SIGIO */
90 	LINUX_SIGXCPU,	/* SIGXCPU */
91 	LINUX_SIGXFSZ,	/* SIGXFSZ */
92 	LINUX_SIGVTALRM,/* SIGVTALRM */
93 	LINUX_SIGPROF,	/* SIGPROF */
94 	LINUX_SIGWINCH,	/* SIGWINCH */
95 	0,		/* SIGINFO */
96 	LINUX_SIGUSR1,	/* SIGUSR1 */
97 	LINUX_SIGUSR2	/* SIGUSR2 */
98 };
99 
100 #define	LINUX_SIGPWREMU	(SIGRTMIN + (LINUX_SIGRTMAX - LINUX_SIGRTMIN) + 1)
101 
102 static int linux_to_bsd_sigtbl[LINUX_SIGTBLSZ] = {
103 	SIGHUP,		/* LINUX_SIGHUP */
104 	SIGINT,		/* LINUX_SIGINT */
105 	SIGQUIT,	/* LINUX_SIGQUIT */
106 	SIGILL,		/* LINUX_SIGILL */
107 	SIGTRAP,	/* LINUX_SIGTRAP */
108 	SIGABRT,	/* LINUX_SIGABRT */
109 	SIGBUS,		/* LINUX_SIGBUS */
110 	SIGFPE,		/* LINUX_SIGFPE */
111 	SIGKILL,	/* LINUX_SIGKILL */
112 	SIGUSR1,	/* LINUX_SIGUSR1 */
113 	SIGSEGV,	/* LINUX_SIGSEGV */
114 	SIGUSR2,	/* LINUX_SIGUSR2 */
115 	SIGPIPE,	/* LINUX_SIGPIPE */
116 	SIGALRM,	/* LINUX_SIGALRM */
117 	SIGTERM,	/* LINUX_SIGTERM */
118 	SIGBUS,		/* LINUX_SIGSTKFLT */
119 	SIGCHLD,	/* LINUX_SIGCHLD */
120 	SIGCONT,	/* LINUX_SIGCONT */
121 	SIGSTOP,	/* LINUX_SIGSTOP */
122 	SIGTSTP,	/* LINUX_SIGTSTP */
123 	SIGTTIN,	/* LINUX_SIGTTIN */
124 	SIGTTOU,	/* LINUX_SIGTTOU */
125 	SIGURG,		/* LINUX_SIGURG */
126 	SIGXCPU,	/* LINUX_SIGXCPU */
127 	SIGXFSZ,	/* LINUX_SIGXFSZ */
128 	SIGVTALRM,	/* LINUX_SIGVTALARM */
129 	SIGPROF,	/* LINUX_SIGPROF */
130 	SIGWINCH,	/* LINUX_SIGWINCH */
131 	SIGIO,		/* LINUX_SIGIO */
132 	/*
133 	 * FreeBSD does not have SIGPWR signal, map Linux SIGPWR signal
134 	 * to the first unused FreeBSD signal number. Since Linux supports
135 	 * signals from 1 to 64 we are ok here as our SIGRTMIN = 65.
136 	 */
137 	LINUX_SIGPWREMU,/* LINUX_SIGPWR */
138 	SIGSYS		/* LINUX_SIGSYS */
139 };
140 
141 static struct cdev *dev_shm_cdev;
142 static struct cdevsw dev_shm_cdevsw = {
143      .d_version = D_VERSION,
144      .d_name    = "dev_shm",
145 };
146 
147 /*
148  * Map Linux RT signals to the FreeBSD RT signals.
149  */
150 static inline int
151 linux_to_bsd_rt_signal(int sig)
152 {
153 
154 	return (SIGRTMIN + sig - LINUX_SIGRTMIN);
155 }
156 
157 static inline int
158 bsd_to_linux_rt_signal(int sig)
159 {
160 
161 	return (sig - SIGRTMIN + LINUX_SIGRTMIN);
162 }
163 
164 int
165 linux_to_bsd_signal(int sig)
166 {
167 
168 	KASSERT(sig > 0 && sig <= LINUX_SIGRTMAX, ("invalid Linux signal %d\n", sig));
169 
170 	if (sig < LINUX_SIGRTMIN)
171 		return (linux_to_bsd_sigtbl[_SIG_IDX(sig)]);
172 
173 	return (linux_to_bsd_rt_signal(sig));
174 }
175 
176 int
177 bsd_to_linux_signal(int sig)
178 {
179 
180 	if (sig <= LINUX_SIGTBLSZ)
181 		return (bsd_to_linux_sigtbl[_SIG_IDX(sig)]);
182 	if (sig == LINUX_SIGPWREMU)
183 		return (LINUX_SIGPWR);
184 
185 	return (bsd_to_linux_rt_signal(sig));
186 }
187 
188 int
189 linux_to_bsd_sigaltstack(int lsa)
190 {
191 	int bsa = 0;
192 
193 	if (lsa & LINUX_SS_DISABLE)
194 		bsa |= SS_DISABLE;
195 	/*
196 	 * Linux ignores SS_ONSTACK flag for ss
197 	 * parameter while FreeBSD prohibits it.
198 	 */
199 	return (bsa);
200 }
201 
202 int
203 bsd_to_linux_sigaltstack(int bsa)
204 {
205 	int lsa = 0;
206 
207 	if (bsa & SS_DISABLE)
208 		lsa |= LINUX_SS_DISABLE;
209 	if (bsa & SS_ONSTACK)
210 		lsa |= LINUX_SS_ONSTACK;
211 	return (lsa);
212 }
213 
214 void
215 linux_to_bsd_sigset(l_sigset_t *lss, sigset_t *bss)
216 {
217 	int b, l;
218 
219 	SIGEMPTYSET(*bss);
220 	for (l = 1; l <= LINUX_SIGRTMAX; l++) {
221 		if (LINUX_SIGISMEMBER(*lss, l)) {
222 			b = linux_to_bsd_signal(l);
223 			if (b)
224 				SIGADDSET(*bss, b);
225 		}
226 	}
227 }
228 
229 void
230 bsd_to_linux_sigset(sigset_t *bss, l_sigset_t *lss)
231 {
232 	int b, l;
233 
234 	LINUX_SIGEMPTYSET(*lss);
235 	for (b = 1; b <= SIGRTMAX; b++) {
236 		if (SIGISMEMBER(*bss, b)) {
237 			l = bsd_to_linux_signal(b);
238 			if (l)
239 				LINUX_SIGADDSET(*lss, l);
240 		}
241 	}
242 }
243 
244 struct ifname_linux_to_bsd_cb_s {
245 	if_t ifp;
246 	const char *lxname;
247 	int unit;
248 	int index;
249 	bool is_lo;
250 	bool is_eth;
251 };
252 
253 static int
254 ifname_linux_to_bsd_cb(if_t ifp, void *arg)
255 {
256 	struct ifname_linux_to_bsd_cb_s *cbs = arg;
257 
258 	/*
259 	 * Allow Linux programs to use FreeBSD names. Don't presume
260 	 * we never have an interface named "eth", so don't make
261 	 * the test optional based on is_eth.
262 	 */
263 	cbs->ifp = ifp;
264 	if (strncmp(if_name(ifp), cbs->lxname, LINUX_IFNAMSIZ) == 0)
265 		return (-1);
266 	if (cbs->is_eth && IFP_IS_ETH(ifp) && cbs->unit == cbs->index++)
267 		return (-1);
268 	if (cbs->is_lo && IFP_IS_LOOP(ifp))
269 		return (-1);
270 	cbs->ifp = NULL;
271 
272 	return (0);
273 }
274 /*
275  * Translate a Linux interface name to a FreeBSD interface name,
276  * and return the associated ifnet structure
277  * bsdname and lxname need to be least IFNAMSIZ bytes long, but
278  * can point to the same buffer.
279  */
280 struct ifnet *
281 ifname_linux_to_bsd(struct thread *td, const char *lxname, char *bsdname)
282 {
283 	struct ifname_linux_to_bsd_cb_s cbs = {};
284 	int len;
285 	char *ep;
286 
287 	cbs.lxname = lxname;
288 	for (len = 0; len < LINUX_IFNAMSIZ; ++len)
289 		if (!isalpha(lxname[len]) || lxname[len] == '\0')
290 			break;
291 	if (len == 0 || len == LINUX_IFNAMSIZ)
292 		return (NULL);
293 	/* Linux loopback interface name is lo (not lo0) */
294 	cbs.is_lo = (len == 2 && strncmp(lxname, "lo", len) == 0);
295 	cbs.unit = (int)strtoul(lxname + len, &ep, 10);
296 	if ((ep == NULL || ep == lxname + len || ep >= lxname + LINUX_IFNAMSIZ) &&
297 	    cbs.is_lo == 0)
298 		return (NULL);
299 	cbs.index = 0;
300 	cbs.is_eth = (len == 3 && strncmp(lxname, "eth", len) == 0);
301 
302 	CURVNET_SET(TD_TO_VNET(td));
303 	IFNET_RLOCK();
304 	if_foreach(ifname_linux_to_bsd_cb, &cbs);
305 	IFNET_RUNLOCK();
306 	CURVNET_RESTORE();
307 	if (cbs.ifp != NULL && bsdname != NULL)
308 		strlcpy(bsdname, if_name(cbs.ifp), IFNAMSIZ);
309 	return (cbs.ifp);
310 }
311 
312 void
313 linux_ifflags(struct ifnet *ifp, short *flags)
314 {
315 	unsigned short fl;
316 
317 	fl = (if_getflags(ifp) | if_getdrvflags(ifp)) & 0xffff;
318 	*flags = 0;
319 	if (fl & IFF_UP)
320 		*flags |= LINUX_IFF_UP;
321 	if (fl & IFF_BROADCAST)
322 		*flags |= LINUX_IFF_BROADCAST;
323 	if (fl & IFF_DEBUG)
324 		*flags |= LINUX_IFF_DEBUG;
325 	if (fl & IFF_LOOPBACK)
326 		*flags |= LINUX_IFF_LOOPBACK;
327 	if (fl & IFF_POINTOPOINT)
328 		*flags |= LINUX_IFF_POINTOPOINT;
329 	if (fl & IFF_DRV_RUNNING)
330 		*flags |= LINUX_IFF_RUNNING;
331 	if (fl & IFF_NOARP)
332 		*flags |= LINUX_IFF_NOARP;
333 	if (fl & IFF_PROMISC)
334 		*flags |= LINUX_IFF_PROMISC;
335 	if (fl & IFF_ALLMULTI)
336 		*flags |= LINUX_IFF_ALLMULTI;
337 	if (fl & IFF_MULTICAST)
338 		*flags |= LINUX_IFF_MULTICAST;
339 }
340 
341 static u_int
342 linux_ifhwaddr_cb(void *arg, struct ifaddr *ifa, u_int count)
343 {
344 	struct sockaddr_dl *sdl = (struct sockaddr_dl *)ifa->ifa_addr;
345 	struct l_sockaddr *lsa = arg;
346 
347 	if (count > 0)
348 		return (0);
349 
350 	if (sdl->sdl_type != IFT_ETHER)
351 		return (0);
352 
353 	bzero(lsa, sizeof(*lsa));
354 	lsa->sa_family = LINUX_ARPHRD_ETHER;
355 	bcopy(LLADDR(sdl), lsa->sa_data, LINUX_IFHWADDRLEN);
356 
357 	return (1);
358 }
359 
360 int
361 linux_ifhwaddr(struct ifnet *ifp, struct l_sockaddr *lsa)
362 {
363 
364 	if (IFP_IS_LOOP(ifp)) {
365 		bzero(lsa, sizeof(*lsa));
366 		lsa->sa_family = LINUX_ARPHRD_LOOPBACK;
367 		return (0);
368 	}
369 
370 	if (!IFP_IS_ETH(ifp))
371 		return (ENOENT);
372 
373 	if (if_foreach_addr_type(ifp, AF_LINK, linux_ifhwaddr_cb, lsa) > 0)
374 		return (0);
375 
376 	return (ENOENT);
377 }
378 
379 int
380 linux_to_bsd_domain(int domain)
381 {
382 
383 	switch (domain) {
384 	case LINUX_AF_UNSPEC:
385 		return (AF_UNSPEC);
386 	case LINUX_AF_UNIX:
387 		return (AF_LOCAL);
388 	case LINUX_AF_INET:
389 		return (AF_INET);
390 	case LINUX_AF_INET6:
391 		return (AF_INET6);
392 	case LINUX_AF_AX25:
393 		return (AF_CCITT);
394 	case LINUX_AF_IPX:
395 		return (AF_IPX);
396 	case LINUX_AF_APPLETALK:
397 		return (AF_APPLETALK);
398 	case LINUX_AF_NETLINK:
399 		return (AF_NETLINK);
400 	}
401 	return (-1);
402 }
403 
404 int
405 bsd_to_linux_domain(int domain)
406 {
407 
408 	switch (domain) {
409 	case AF_UNSPEC:
410 		return (LINUX_AF_UNSPEC);
411 	case AF_LOCAL:
412 		return (LINUX_AF_UNIX);
413 	case AF_INET:
414 		return (LINUX_AF_INET);
415 	case AF_INET6:
416 		return (LINUX_AF_INET6);
417 	case AF_CCITT:
418 		return (LINUX_AF_AX25);
419 	case AF_IPX:
420 		return (LINUX_AF_IPX);
421 	case AF_APPLETALK:
422 		return (LINUX_AF_APPLETALK);
423 	case AF_NETLINK:
424 		return (LINUX_AF_NETLINK);
425 	}
426 	return (-1);
427 }
428 
429 /*
430  * Based on the fact that:
431  * 1. Native and Linux storage of struct sockaddr
432  * and struct sockaddr_in6 are equal.
433  * 2. On Linux sa_family is the first member of all struct sockaddr.
434  */
435 int
436 bsd_to_linux_sockaddr(const struct sockaddr *sa, struct l_sockaddr **lsa,
437     socklen_t len)
438 {
439 	struct l_sockaddr *kosa;
440 	int bdom;
441 
442 	*lsa = NULL;
443 	if (len < 2 || len > UCHAR_MAX)
444 		return (EINVAL);
445 	bdom = bsd_to_linux_domain(sa->sa_family);
446 	if (bdom == -1)
447 		return (EAFNOSUPPORT);
448 
449 	kosa = malloc(len, M_LINUX, M_WAITOK);
450 	bcopy(sa, kosa, len);
451 	kosa->sa_family = bdom;
452 	*lsa = kosa;
453 	return (0);
454 }
455 
456 int
457 linux_to_bsd_sockaddr(const struct l_sockaddr *osa, struct sockaddr **sap,
458     socklen_t *len)
459 {
460 	struct sockaddr *sa;
461 	struct l_sockaddr *kosa;
462 #ifdef INET6
463 	struct sockaddr_in6 *sin6;
464 	bool  oldv6size;
465 #endif
466 	char *name;
467 	int salen, bdom, error, hdrlen, namelen;
468 
469 	if (*len < 2 || *len > UCHAR_MAX)
470 		return (EINVAL);
471 
472 	salen = *len;
473 
474 #ifdef INET6
475 	oldv6size = false;
476 	/*
477 	 * Check for old (pre-RFC2553) sockaddr_in6. We may accept it
478 	 * if it's a v4-mapped address, so reserve the proper space
479 	 * for it.
480 	 */
481 	if (salen == sizeof(struct sockaddr_in6) - sizeof(uint32_t)) {
482 		salen += sizeof(uint32_t);
483 		oldv6size = true;
484 	}
485 #endif
486 
487 	kosa = malloc(salen, M_SONAME, M_WAITOK);
488 
489 	if ((error = copyin(osa, kosa, *len)))
490 		goto out;
491 
492 	bdom = linux_to_bsd_domain(kosa->sa_family);
493 	if (bdom == -1) {
494 		error = EAFNOSUPPORT;
495 		goto out;
496 	}
497 
498 #ifdef INET6
499 	/*
500 	 * Older Linux IPv6 code uses obsolete RFC2133 struct sockaddr_in6,
501 	 * which lacks the scope id compared with RFC2553 one. If we detect
502 	 * the situation, reject the address and write a message to system log.
503 	 *
504 	 * Still accept addresses for which the scope id is not used.
505 	 */
506 	if (oldv6size) {
507 		if (bdom == AF_INET6) {
508 			sin6 = (struct sockaddr_in6 *)kosa;
509 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr) ||
510 			    (!IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) &&
511 			     !IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr) &&
512 			     !IN6_IS_ADDR_V4COMPAT(&sin6->sin6_addr) &&
513 			     !IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr) &&
514 			     !IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))) {
515 				sin6->sin6_scope_id = 0;
516 			} else {
517 				linux_msg(curthread,
518 				    "obsolete pre-RFC2553 sockaddr_in6 rejected");
519 				error = EINVAL;
520 				goto out;
521 			}
522 		} else
523 			salen -= sizeof(uint32_t);
524 	}
525 #endif
526 	if (bdom == AF_INET) {
527 		if (salen < sizeof(struct sockaddr_in)) {
528 			error = EINVAL;
529 			goto out;
530 		}
531 		salen = sizeof(struct sockaddr_in);
532 	}
533 
534 	if (bdom == AF_LOCAL && salen > sizeof(struct sockaddr_un)) {
535 		hdrlen = offsetof(struct sockaddr_un, sun_path);
536 		name = ((struct sockaddr_un *)kosa)->sun_path;
537 		if (*name == '\0') {
538 			/*
539 			 * Linux abstract namespace starts with a NULL byte.
540 			 * XXX We do not support abstract namespace yet.
541 			 */
542 			namelen = strnlen(name + 1, salen - hdrlen - 1) + 1;
543 		} else
544 			namelen = strnlen(name, salen - hdrlen);
545 		salen = hdrlen + namelen;
546 		if (salen > sizeof(struct sockaddr_un)) {
547 			error = ENAMETOOLONG;
548 			goto out;
549 		}
550 	}
551 
552 	if (bdom == AF_NETLINK) {
553 		if (salen < sizeof(struct sockaddr_nl)) {
554 			error = EINVAL;
555 			goto out;
556 		}
557 		salen = sizeof(struct sockaddr_nl);
558 	}
559 
560 	sa = (struct sockaddr *)kosa;
561 	sa->sa_family = bdom;
562 	sa->sa_len = salen;
563 
564 	*sap = sa;
565 	*len = salen;
566 	return (0);
567 
568 out:
569 	free(kosa, M_SONAME);
570 	return (error);
571 }
572 
573 void
574 linux_dev_shm_create(void)
575 {
576 	int error;
577 
578 	error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &dev_shm_cdev,
579 	    &dev_shm_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0, "shm/.mountpoint");
580 	if (error != 0) {
581 		printf("%s: failed to create device node, error %d\n",
582 		    __func__, error);
583 	}
584 }
585 
586 void
587 linux_dev_shm_destroy(void)
588 {
589 
590 	destroy_dev(dev_shm_cdev);
591 }
592 
593 int
594 bsd_to_linux_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
595     size_t mapcnt, int no_value)
596 {
597 	int bsd_mask, bsd_value, linux_mask, linux_value;
598 	int linux_ret;
599 	size_t i;
600 	bool applied;
601 
602 	applied = false;
603 	linux_ret = 0;
604 	for (i = 0; i < mapcnt; ++i) {
605 		bsd_mask = bitmap[i].bsd_mask;
606 		bsd_value = bitmap[i].bsd_value;
607 		if (bsd_mask == 0)
608 			bsd_mask = bsd_value;
609 
610 		linux_mask = bitmap[i].linux_mask;
611 		linux_value = bitmap[i].linux_value;
612 		if (linux_mask == 0)
613 			linux_mask = linux_value;
614 
615 		/*
616 		 * If a mask larger than just the value is set, we explicitly
617 		 * want to make sure that only this bit we mapped within that
618 		 * mask is set.
619 		 */
620 		if ((value & bsd_mask) == bsd_value) {
621 			linux_ret = (linux_ret & ~linux_mask) | linux_value;
622 			applied = true;
623 		}
624 	}
625 
626 	if (!applied)
627 		return (no_value);
628 	return (linux_ret);
629 }
630 
631 int
632 linux_to_bsd_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
633     size_t mapcnt, int no_value)
634 {
635 	int bsd_mask, bsd_value, linux_mask, linux_value;
636 	int bsd_ret;
637 	size_t i;
638 	bool applied;
639 
640 	applied = false;
641 	bsd_ret = 0;
642 	for (i = 0; i < mapcnt; ++i) {
643 		bsd_mask = bitmap[i].bsd_mask;
644 		bsd_value = bitmap[i].bsd_value;
645 		if (bsd_mask == 0)
646 			bsd_mask = bsd_value;
647 
648 		linux_mask = bitmap[i].linux_mask;
649 		linux_value = bitmap[i].linux_value;
650 		if (linux_mask == 0)
651 			linux_mask = linux_value;
652 
653 		/*
654 		 * If a mask larger than just the value is set, we explicitly
655 		 * want to make sure that only this bit we mapped within that
656 		 * mask is set.
657 		 */
658 		if ((value & linux_mask) == linux_value) {
659 			bsd_ret = (bsd_ret & ~bsd_mask) | bsd_value;
660 			applied = true;
661 		}
662 	}
663 
664 	if (!applied)
665 		return (no_value);
666 	return (bsd_ret);
667 }
668 
669 void
670 linux_to_bsd_poll_events(struct thread *td, int fd, short lev,
671     short *bev)
672 {
673 	struct file *fp;
674 	int error;
675 	short bits = 0;
676 
677 	if (lev & LINUX_POLLIN)
678 		bits |= POLLIN;
679 	if (lev & LINUX_POLLPRI)
680 		bits |=	POLLPRI;
681 	if (lev & LINUX_POLLOUT)
682 		bits |= POLLOUT;
683 	if (lev & LINUX_POLLERR)
684 		bits |= POLLERR;
685 	if (lev & LINUX_POLLHUP)
686 		bits |= POLLHUP;
687 	if (lev & LINUX_POLLNVAL)
688 		bits |= POLLNVAL;
689 	if (lev & LINUX_POLLRDNORM)
690 		bits |= POLLRDNORM;
691 	if (lev & LINUX_POLLRDBAND)
692 		bits |= POLLRDBAND;
693 	if (lev & LINUX_POLLWRBAND)
694 		bits |= POLLWRBAND;
695 	if (lev & LINUX_POLLWRNORM)
696 		bits |= POLLWRNORM;
697 
698 	if (lev & LINUX_POLLRDHUP) {
699 		/*
700 		 * It seems that the Linux silencly ignores POLLRDHUP
701 		 * on non-socket file descriptors unlike FreeBSD, where
702 		 * events bits is more strictly checked (POLLSTANDARD).
703 		 */
704 		error = fget_unlocked(td, fd, &cap_no_rights, &fp);
705 		if (error == 0) {
706 			/*
707 			 * XXX. On FreeBSD POLLRDHUP applies only to
708 			 * stream sockets.
709 			 */
710 			if (fp->f_type == DTYPE_SOCKET)
711 				bits |= POLLRDHUP;
712 			fdrop(fp, td);
713 		}
714 	}
715 
716 	if (lev & LINUX_POLLMSG)
717 		LINUX_RATELIMIT_MSG_OPT1("unsupported POLLMSG, events(%d)", lev);
718 	if (lev & LINUX_POLLREMOVE)
719 		LINUX_RATELIMIT_MSG_OPT1("unsupported POLLREMOVE, events(%d)", lev);
720 
721 	*bev = bits;
722 }
723 
724 void
725 bsd_to_linux_poll_events(short bev, short *lev)
726 {
727 	short bits = 0;
728 
729 	if (bev & POLLIN)
730 		bits |= LINUX_POLLIN;
731 	if (bev & POLLPRI)
732 		bits |=	LINUX_POLLPRI;
733 	if (bev & (POLLOUT | POLLWRNORM))
734 		/*
735 		 * POLLWRNORM is equal to POLLOUT on FreeBSD,
736 		 * but not on Linux
737 		 */
738 		bits |= LINUX_POLLOUT;
739 	if (bev & POLLERR)
740 		bits |= LINUX_POLLERR;
741 	if (bev & POLLHUP)
742 		bits |= LINUX_POLLHUP;
743 	if (bev & POLLNVAL)
744 		bits |= LINUX_POLLNVAL;
745 	if (bev & POLLRDNORM)
746 		bits |= LINUX_POLLRDNORM;
747 	if (bev & POLLRDBAND)
748 		bits |= LINUX_POLLRDBAND;
749 	if (bev & POLLWRBAND)
750 		bits |= LINUX_POLLWRBAND;
751 	if (bev & POLLRDHUP)
752 		bits |= LINUX_POLLRDHUP;
753 
754 	*lev = bits;
755 }
756 
757 bool
758 linux_use_real_ifname(const struct ifnet *ifp)
759 {
760 
761 	return (use_real_ifnames || !IFP_IS_ETH(__DECONST(if_t, ifp)));
762 }
763