xref: /freebsd/sys/compat/linux/linux.c (revision b97ee269eae3cbaf35c18f51a459aea581c2a7dc)
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/systm.h>
33 #include <sys/conf.h>
34 #include <sys/ctype.h>
35 #include <sys/file.h>
36 #include <sys/filedesc.h>
37 #include <sys/jail.h>
38 #include <sys/lock.h>
39 #include <sys/malloc.h>
40 #include <sys/poll.h>
41 #include <sys/proc.h>
42 #include <sys/signalvar.h>
43 #include <sys/socket.h>
44 #include <sys/socketvar.h>
45 
46 #include <net/if.h>
47 #include <net/if_var.h>
48 #include <net/if_dl.h>
49 #include <net/if_types.h>
50 #include <netlink/netlink.h>
51 
52 #include <sys/un.h>
53 #include <netinet/in.h>
54 
55 #include <compat/linux/linux.h>
56 #include <compat/linux/linux_common.h>
57 #include <compat/linux/linux_mib.h>
58 #include <compat/linux/linux_util.h>
59 
60 CTASSERT(LINUX_IFNAMSIZ == IFNAMSIZ);
61 
62 static int bsd_to_linux_sigtbl[LINUX_SIGTBLSZ] = {
63 	LINUX_SIGHUP,	/* SIGHUP */
64 	LINUX_SIGINT,	/* SIGINT */
65 	LINUX_SIGQUIT,	/* SIGQUIT */
66 	LINUX_SIGILL,	/* SIGILL */
67 	LINUX_SIGTRAP,	/* SIGTRAP */
68 	LINUX_SIGABRT,	/* SIGABRT */
69 	0,		/* SIGEMT */
70 	LINUX_SIGFPE,	/* SIGFPE */
71 	LINUX_SIGKILL,	/* SIGKILL */
72 	LINUX_SIGBUS,	/* SIGBUS */
73 	LINUX_SIGSEGV,	/* SIGSEGV */
74 	LINUX_SIGSYS,	/* SIGSYS */
75 	LINUX_SIGPIPE,	/* SIGPIPE */
76 	LINUX_SIGALRM,	/* SIGALRM */
77 	LINUX_SIGTERM,	/* SIGTERM */
78 	LINUX_SIGURG,	/* SIGURG */
79 	LINUX_SIGSTOP,	/* SIGSTOP */
80 	LINUX_SIGTSTP,	/* SIGTSTP */
81 	LINUX_SIGCONT,	/* SIGCONT */
82 	LINUX_SIGCHLD,	/* SIGCHLD */
83 	LINUX_SIGTTIN,	/* SIGTTIN */
84 	LINUX_SIGTTOU,	/* SIGTTOU */
85 	LINUX_SIGIO,	/* SIGIO */
86 	LINUX_SIGXCPU,	/* SIGXCPU */
87 	LINUX_SIGXFSZ,	/* SIGXFSZ */
88 	LINUX_SIGVTALRM,/* SIGVTALRM */
89 	LINUX_SIGPROF,	/* SIGPROF */
90 	LINUX_SIGWINCH,	/* SIGWINCH */
91 	0,		/* SIGINFO */
92 	LINUX_SIGUSR1,	/* SIGUSR1 */
93 	LINUX_SIGUSR2	/* SIGUSR2 */
94 };
95 
96 #define	LINUX_SIGPWREMU	(SIGRTMIN + (LINUX_SIGRTMAX - LINUX_SIGRTMIN) + 1)
97 
98 static int linux_to_bsd_sigtbl[LINUX_SIGTBLSZ] = {
99 	SIGHUP,		/* LINUX_SIGHUP */
100 	SIGINT,		/* LINUX_SIGINT */
101 	SIGQUIT,	/* LINUX_SIGQUIT */
102 	SIGILL,		/* LINUX_SIGILL */
103 	SIGTRAP,	/* LINUX_SIGTRAP */
104 	SIGABRT,	/* LINUX_SIGABRT */
105 	SIGBUS,		/* LINUX_SIGBUS */
106 	SIGFPE,		/* LINUX_SIGFPE */
107 	SIGKILL,	/* LINUX_SIGKILL */
108 	SIGUSR1,	/* LINUX_SIGUSR1 */
109 	SIGSEGV,	/* LINUX_SIGSEGV */
110 	SIGUSR2,	/* LINUX_SIGUSR2 */
111 	SIGPIPE,	/* LINUX_SIGPIPE */
112 	SIGALRM,	/* LINUX_SIGALRM */
113 	SIGTERM,	/* LINUX_SIGTERM */
114 	SIGBUS,		/* LINUX_SIGSTKFLT */
115 	SIGCHLD,	/* LINUX_SIGCHLD */
116 	SIGCONT,	/* LINUX_SIGCONT */
117 	SIGSTOP,	/* LINUX_SIGSTOP */
118 	SIGTSTP,	/* LINUX_SIGTSTP */
119 	SIGTTIN,	/* LINUX_SIGTTIN */
120 	SIGTTOU,	/* LINUX_SIGTTOU */
121 	SIGURG,		/* LINUX_SIGURG */
122 	SIGXCPU,	/* LINUX_SIGXCPU */
123 	SIGXFSZ,	/* LINUX_SIGXFSZ */
124 	SIGVTALRM,	/* LINUX_SIGVTALARM */
125 	SIGPROF,	/* LINUX_SIGPROF */
126 	SIGWINCH,	/* LINUX_SIGWINCH */
127 	SIGIO,		/* LINUX_SIGIO */
128 	/*
129 	 * FreeBSD does not have SIGPWR signal, map Linux SIGPWR signal
130 	 * to the first unused FreeBSD signal number. Since Linux supports
131 	 * signals from 1 to 64 we are ok here as our SIGRTMIN = 65.
132 	 */
133 	LINUX_SIGPWREMU,/* LINUX_SIGPWR */
134 	SIGSYS		/* LINUX_SIGSYS */
135 };
136 
137 static struct cdev *dev_shm_cdev;
138 static struct cdevsw dev_shm_cdevsw = {
139      .d_version = D_VERSION,
140      .d_name    = "dev_shm",
141 };
142 
143 /*
144  * Map Linux RT signals to the FreeBSD RT signals.
145  */
146 static inline int
147 linux_to_bsd_rt_signal(int sig)
148 {
149 
150 	return (SIGRTMIN + sig - LINUX_SIGRTMIN);
151 }
152 
153 static inline int
154 bsd_to_linux_rt_signal(int sig)
155 {
156 
157 	return (sig - SIGRTMIN + LINUX_SIGRTMIN);
158 }
159 
160 int
161 linux_to_bsd_signal(int sig)
162 {
163 
164 	KASSERT(sig > 0 && sig <= LINUX_SIGRTMAX, ("invalid Linux signal %d\n", sig));
165 
166 	if (sig < LINUX_SIGRTMIN)
167 		return (linux_to_bsd_sigtbl[_SIG_IDX(sig)]);
168 
169 	return (linux_to_bsd_rt_signal(sig));
170 }
171 
172 int
173 bsd_to_linux_signal(int sig)
174 {
175 
176 	if (sig <= LINUX_SIGTBLSZ)
177 		return (bsd_to_linux_sigtbl[_SIG_IDX(sig)]);
178 	if (sig == LINUX_SIGPWREMU)
179 		return (LINUX_SIGPWR);
180 
181 	return (bsd_to_linux_rt_signal(sig));
182 }
183 
184 int
185 linux_to_bsd_sigaltstack(int lsa)
186 {
187 	int bsa = 0;
188 
189 	if (lsa & LINUX_SS_DISABLE)
190 		bsa |= SS_DISABLE;
191 	/*
192 	 * Linux ignores SS_ONSTACK flag for ss
193 	 * parameter while FreeBSD prohibits it.
194 	 */
195 	return (bsa);
196 }
197 
198 int
199 bsd_to_linux_sigaltstack(int bsa)
200 {
201 	int lsa = 0;
202 
203 	if (bsa & SS_DISABLE)
204 		lsa |= LINUX_SS_DISABLE;
205 	if (bsa & SS_ONSTACK)
206 		lsa |= LINUX_SS_ONSTACK;
207 	return (lsa);
208 }
209 
210 void
211 linux_to_bsd_sigset(l_sigset_t *lss, sigset_t *bss)
212 {
213 	int b, l;
214 
215 	SIGEMPTYSET(*bss);
216 	for (l = 1; l <= LINUX_SIGRTMAX; l++) {
217 		if (LINUX_SIGISMEMBER(*lss, l)) {
218 			b = linux_to_bsd_signal(l);
219 			if (b)
220 				SIGADDSET(*bss, b);
221 		}
222 	}
223 }
224 
225 void
226 bsd_to_linux_sigset(sigset_t *bss, l_sigset_t *lss)
227 {
228 	int b, l;
229 
230 	LINUX_SIGEMPTYSET(*lss);
231 	for (b = 1; b <= SIGRTMAX; b++) {
232 		if (SIGISMEMBER(*bss, b)) {
233 			l = bsd_to_linux_signal(b);
234 			if (l)
235 				LINUX_SIGADDSET(*lss, l);
236 		}
237 	}
238 }
239 
240 /*
241  * Translate a Linux interface name to a FreeBSD interface name,
242  * and return the associated ifnet structure
243  * bsdname and lxname need to be least IFNAMSIZ bytes long, but
244  * can point to the same buffer.
245  */
246 struct ifnet *
247 ifname_linux_to_bsd(struct thread *td, const char *lxname, char *bsdname)
248 {
249 	struct ifnet *ifp;
250 	int len, unit;
251 	char *ep;
252 	int index;
253 	bool is_eth, is_lo;
254 
255 	for (len = 0; len < LINUX_IFNAMSIZ; ++len)
256 		if (!isalpha(lxname[len]) || lxname[len] == '\0')
257 			break;
258 	if (len == 0 || len == LINUX_IFNAMSIZ)
259 		return (NULL);
260 	/* Linux loopback interface name is lo (not lo0) */
261 	is_lo = (len == 2 && strncmp(lxname, "lo", len) == 0);
262 	unit = (int)strtoul(lxname + len, &ep, 10);
263 	if ((ep == NULL || ep == lxname + len || ep >= lxname + LINUX_IFNAMSIZ) &&
264 	    is_lo == 0)
265 		return (NULL);
266 	index = 0;
267 	is_eth = (len == 3 && strncmp(lxname, "eth", len) == 0);
268 
269 	CURVNET_SET(TD_TO_VNET(td));
270 	IFNET_RLOCK();
271 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
272 		/*
273 		 * Allow Linux programs to use FreeBSD names. Don't presume
274 		 * we never have an interface named "eth", so don't make
275 		 * the test optional based on is_eth.
276 		 */
277 		if (strncmp(ifp->if_xname, lxname, LINUX_IFNAMSIZ) == 0)
278 			break;
279 		if (is_eth && IFP_IS_ETH(ifp) && unit == index++)
280 			break;
281 		if (is_lo && IFP_IS_LOOP(ifp))
282 			break;
283 	}
284 	IFNET_RUNLOCK();
285 	CURVNET_RESTORE();
286 	if (ifp != NULL && bsdname != NULL)
287 		strlcpy(bsdname, ifp->if_xname, IFNAMSIZ);
288 	return (ifp);
289 }
290 
291 void
292 linux_ifflags(struct ifnet *ifp, short *flags)
293 {
294 	unsigned short fl;
295 
296 	fl = (ifp->if_flags | ifp->if_drv_flags) & 0xffff;
297 	*flags = 0;
298 	if (fl & IFF_UP)
299 		*flags |= LINUX_IFF_UP;
300 	if (fl & IFF_BROADCAST)
301 		*flags |= LINUX_IFF_BROADCAST;
302 	if (fl & IFF_DEBUG)
303 		*flags |= LINUX_IFF_DEBUG;
304 	if (fl & IFF_LOOPBACK)
305 		*flags |= LINUX_IFF_LOOPBACK;
306 	if (fl & IFF_POINTOPOINT)
307 		*flags |= LINUX_IFF_POINTOPOINT;
308 	if (fl & IFF_DRV_RUNNING)
309 		*flags |= LINUX_IFF_RUNNING;
310 	if (fl & IFF_NOARP)
311 		*flags |= LINUX_IFF_NOARP;
312 	if (fl & IFF_PROMISC)
313 		*flags |= LINUX_IFF_PROMISC;
314 	if (fl & IFF_ALLMULTI)
315 		*flags |= LINUX_IFF_ALLMULTI;
316 	if (fl & IFF_MULTICAST)
317 		*flags |= LINUX_IFF_MULTICAST;
318 }
319 
320 int
321 linux_ifhwaddr(struct ifnet *ifp, struct l_sockaddr *lsa)
322 {
323 	struct ifaddr *ifa;
324 	struct sockaddr_dl *sdl;
325 
326 	if (IFP_IS_LOOP(ifp)) {
327 		bzero(lsa, sizeof(*lsa));
328 		lsa->sa_family = LINUX_ARPHRD_LOOPBACK;
329 		return (0);
330 	}
331 
332 	if (!IFP_IS_ETH(ifp))
333 		return (ENOENT);
334 
335 	CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
336 		sdl = (struct sockaddr_dl*)ifa->ifa_addr;
337 		if (sdl != NULL && (sdl->sdl_family == AF_LINK) &&
338 		    (sdl->sdl_type == IFT_ETHER)) {
339 			bzero(lsa, sizeof(*lsa));
340 			lsa->sa_family = LINUX_ARPHRD_ETHER;
341 			bcopy(LLADDR(sdl), lsa->sa_data, LINUX_IFHWADDRLEN);
342 			return (0);
343 		}
344 	}
345 
346 	return (ENOENT);
347 }
348 
349 int
350 linux_to_bsd_domain(int domain)
351 {
352 
353 	switch (domain) {
354 	case LINUX_AF_UNSPEC:
355 		return (AF_UNSPEC);
356 	case LINUX_AF_UNIX:
357 		return (AF_LOCAL);
358 	case LINUX_AF_INET:
359 		return (AF_INET);
360 	case LINUX_AF_INET6:
361 		return (AF_INET6);
362 	case LINUX_AF_AX25:
363 		return (AF_CCITT);
364 	case LINUX_AF_IPX:
365 		return (AF_IPX);
366 	case LINUX_AF_APPLETALK:
367 		return (AF_APPLETALK);
368 	case LINUX_AF_NETLINK:
369 		return (AF_NETLINK);
370 	}
371 	return (-1);
372 }
373 
374 int
375 bsd_to_linux_domain(int domain)
376 {
377 
378 	switch (domain) {
379 	case AF_UNSPEC:
380 		return (LINUX_AF_UNSPEC);
381 	case AF_LOCAL:
382 		return (LINUX_AF_UNIX);
383 	case AF_INET:
384 		return (LINUX_AF_INET);
385 	case AF_INET6:
386 		return (LINUX_AF_INET6);
387 	case AF_CCITT:
388 		return (LINUX_AF_AX25);
389 	case AF_IPX:
390 		return (LINUX_AF_IPX);
391 	case AF_APPLETALK:
392 		return (LINUX_AF_APPLETALK);
393 	case AF_NETLINK:
394 		return (LINUX_AF_NETLINK);
395 	}
396 	return (-1);
397 }
398 
399 /*
400  * Based on the fact that:
401  * 1. Native and Linux storage of struct sockaddr
402  * and struct sockaddr_in6 are equal.
403  * 2. On Linux sa_family is the first member of all struct sockaddr.
404  */
405 int
406 bsd_to_linux_sockaddr(const struct sockaddr *sa, struct l_sockaddr **lsa,
407     socklen_t len)
408 {
409 	struct l_sockaddr *kosa;
410 	int bdom;
411 
412 	*lsa = NULL;
413 	if (len < 2 || len > UCHAR_MAX)
414 		return (EINVAL);
415 	bdom = bsd_to_linux_domain(sa->sa_family);
416 	if (bdom == -1)
417 		return (EAFNOSUPPORT);
418 
419 	kosa = malloc(len, M_LINUX, M_WAITOK);
420 	bcopy(sa, kosa, len);
421 	kosa->sa_family = bdom;
422 	*lsa = kosa;
423 	return (0);
424 }
425 
426 int
427 linux_to_bsd_sockaddr(const struct l_sockaddr *osa, struct sockaddr **sap,
428     socklen_t *len)
429 {
430 	struct sockaddr *sa;
431 	struct l_sockaddr *kosa;
432 #ifdef INET6
433 	struct sockaddr_in6 *sin6;
434 	bool  oldv6size;
435 #endif
436 	char *name;
437 	int salen, bdom, error, hdrlen, namelen;
438 
439 	if (*len < 2 || *len > UCHAR_MAX)
440 		return (EINVAL);
441 
442 	salen = *len;
443 
444 #ifdef INET6
445 	oldv6size = false;
446 	/*
447 	 * Check for old (pre-RFC2553) sockaddr_in6. We may accept it
448 	 * if it's a v4-mapped address, so reserve the proper space
449 	 * for it.
450 	 */
451 	if (salen == sizeof(struct sockaddr_in6) - sizeof(uint32_t)) {
452 		salen += sizeof(uint32_t);
453 		oldv6size = true;
454 	}
455 #endif
456 
457 	kosa = malloc(salen, M_SONAME, M_WAITOK);
458 
459 	if ((error = copyin(osa, kosa, *len)))
460 		goto out;
461 
462 	bdom = linux_to_bsd_domain(kosa->sa_family);
463 	if (bdom == -1) {
464 		error = EAFNOSUPPORT;
465 		goto out;
466 	}
467 
468 #ifdef INET6
469 	/*
470 	 * Older Linux IPv6 code uses obsolete RFC2133 struct sockaddr_in6,
471 	 * which lacks the scope id compared with RFC2553 one. If we detect
472 	 * the situation, reject the address and write a message to system log.
473 	 *
474 	 * Still accept addresses for which the scope id is not used.
475 	 */
476 	if (oldv6size) {
477 		if (bdom == AF_INET6) {
478 			sin6 = (struct sockaddr_in6 *)kosa;
479 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr) ||
480 			    (!IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) &&
481 			     !IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr) &&
482 			     !IN6_IS_ADDR_V4COMPAT(&sin6->sin6_addr) &&
483 			     !IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr) &&
484 			     !IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))) {
485 				sin6->sin6_scope_id = 0;
486 			} else {
487 				linux_msg(curthread,
488 				    "obsolete pre-RFC2553 sockaddr_in6 rejected");
489 				error = EINVAL;
490 				goto out;
491 			}
492 		} else
493 			salen -= sizeof(uint32_t);
494 	}
495 #endif
496 	if (bdom == AF_INET) {
497 		if (salen < sizeof(struct sockaddr_in)) {
498 			error = EINVAL;
499 			goto out;
500 		}
501 		salen = sizeof(struct sockaddr_in);
502 	}
503 
504 	if (bdom == AF_LOCAL && salen > sizeof(struct sockaddr_un)) {
505 		hdrlen = offsetof(struct sockaddr_un, sun_path);
506 		name = ((struct sockaddr_un *)kosa)->sun_path;
507 		if (*name == '\0') {
508 			/*
509 			 * Linux abstract namespace starts with a NULL byte.
510 			 * XXX We do not support abstract namespace yet.
511 			 */
512 			namelen = strnlen(name + 1, salen - hdrlen - 1) + 1;
513 		} else
514 			namelen = strnlen(name, salen - hdrlen);
515 		salen = hdrlen + namelen;
516 		if (salen > sizeof(struct sockaddr_un)) {
517 			error = ENAMETOOLONG;
518 			goto out;
519 		}
520 	}
521 
522 	if (bdom == AF_NETLINK) {
523 		if (salen < sizeof(struct sockaddr_nl)) {
524 			error = EINVAL;
525 			goto out;
526 		}
527 		salen = sizeof(struct sockaddr_nl);
528 	}
529 
530 	sa = (struct sockaddr *)kosa;
531 	sa->sa_family = bdom;
532 	sa->sa_len = salen;
533 
534 	*sap = sa;
535 	*len = salen;
536 	return (0);
537 
538 out:
539 	free(kosa, M_SONAME);
540 	return (error);
541 }
542 
543 void
544 linux_dev_shm_create(void)
545 {
546 	int error;
547 
548 	error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &dev_shm_cdev,
549 	    &dev_shm_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0, "shm/.mountpoint");
550 	if (error != 0) {
551 		printf("%s: failed to create device node, error %d\n",
552 		    __func__, error);
553 	}
554 }
555 
556 void
557 linux_dev_shm_destroy(void)
558 {
559 
560 	destroy_dev(dev_shm_cdev);
561 }
562 
563 int
564 bsd_to_linux_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
565     size_t mapcnt, int no_value)
566 {
567 	int bsd_mask, bsd_value, linux_mask, linux_value;
568 	int linux_ret;
569 	size_t i;
570 	bool applied;
571 
572 	applied = false;
573 	linux_ret = 0;
574 	for (i = 0; i < mapcnt; ++i) {
575 		bsd_mask = bitmap[i].bsd_mask;
576 		bsd_value = bitmap[i].bsd_value;
577 		if (bsd_mask == 0)
578 			bsd_mask = bsd_value;
579 
580 		linux_mask = bitmap[i].linux_mask;
581 		linux_value = bitmap[i].linux_value;
582 		if (linux_mask == 0)
583 			linux_mask = linux_value;
584 
585 		/*
586 		 * If a mask larger than just the value is set, we explicitly
587 		 * want to make sure that only this bit we mapped within that
588 		 * mask is set.
589 		 */
590 		if ((value & bsd_mask) == bsd_value) {
591 			linux_ret = (linux_ret & ~linux_mask) | linux_value;
592 			applied = true;
593 		}
594 	}
595 
596 	if (!applied)
597 		return (no_value);
598 	return (linux_ret);
599 }
600 
601 int
602 linux_to_bsd_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
603     size_t mapcnt, int no_value)
604 {
605 	int bsd_mask, bsd_value, linux_mask, linux_value;
606 	int bsd_ret;
607 	size_t i;
608 	bool applied;
609 
610 	applied = false;
611 	bsd_ret = 0;
612 	for (i = 0; i < mapcnt; ++i) {
613 		bsd_mask = bitmap[i].bsd_mask;
614 		bsd_value = bitmap[i].bsd_value;
615 		if (bsd_mask == 0)
616 			bsd_mask = bsd_value;
617 
618 		linux_mask = bitmap[i].linux_mask;
619 		linux_value = bitmap[i].linux_value;
620 		if (linux_mask == 0)
621 			linux_mask = linux_value;
622 
623 		/*
624 		 * If a mask larger than just the value is set, we explicitly
625 		 * want to make sure that only this bit we mapped within that
626 		 * mask is set.
627 		 */
628 		if ((value & linux_mask) == linux_value) {
629 			bsd_ret = (bsd_ret & ~bsd_mask) | bsd_value;
630 			applied = true;
631 		}
632 	}
633 
634 	if (!applied)
635 		return (no_value);
636 	return (bsd_ret);
637 }
638 
639 void
640 linux_to_bsd_poll_events(struct thread *td, int fd, short lev,
641     short *bev)
642 {
643 	struct file *fp;
644 	int error;
645 	short bits = 0;
646 
647 	if (lev & LINUX_POLLIN)
648 		bits |= POLLIN;
649 	if (lev & LINUX_POLLPRI)
650 		bits |=	POLLPRI;
651 	if (lev & LINUX_POLLOUT)
652 		bits |= POLLOUT;
653 	if (lev & LINUX_POLLERR)
654 		bits |= POLLERR;
655 	if (lev & LINUX_POLLHUP)
656 		bits |= POLLHUP;
657 	if (lev & LINUX_POLLNVAL)
658 		bits |= POLLNVAL;
659 	if (lev & LINUX_POLLRDNORM)
660 		bits |= POLLRDNORM;
661 	if (lev & LINUX_POLLRDBAND)
662 		bits |= POLLRDBAND;
663 	if (lev & LINUX_POLLWRBAND)
664 		bits |= POLLWRBAND;
665 	if (lev & LINUX_POLLWRNORM)
666 		bits |= POLLWRNORM;
667 
668 	if (lev & LINUX_POLLRDHUP) {
669 		/*
670 		 * It seems that the Linux silencly ignores POLLRDHUP
671 		 * on non-socket file descriptors unlike FreeBSD, where
672 		 * events bits is more strictly checked (POLLSTANDARD).
673 		 */
674 		error = fget_unlocked(td, fd, &cap_no_rights, &fp);
675 		if (error == 0) {
676 			/*
677 			 * XXX. On FreeBSD POLLRDHUP applies only to
678 			 * stream sockets.
679 			 */
680 			if (fp->f_type == DTYPE_SOCKET)
681 				bits |= POLLRDHUP;
682 			fdrop(fp, td);
683 		}
684 	}
685 
686 	if (lev & LINUX_POLLMSG)
687 		LINUX_RATELIMIT_MSG_OPT1("unsupported POLLMSG, events(%d)", lev);
688 	if (lev & LINUX_POLLREMOVE)
689 		LINUX_RATELIMIT_MSG_OPT1("unsupported POLLREMOVE, events(%d)", lev);
690 
691 	*bev = bits;
692 }
693 
694 void
695 bsd_to_linux_poll_events(short bev, short *lev)
696 {
697 	short bits = 0;
698 
699 	if (bev & POLLIN)
700 		bits |= LINUX_POLLIN;
701 	if (bev & POLLPRI)
702 		bits |=	LINUX_POLLPRI;
703 	if (bev & (POLLOUT | POLLWRNORM))
704 		/*
705 		 * POLLWRNORM is equal to POLLOUT on FreeBSD,
706 		 * but not on Linux
707 		 */
708 		bits |= LINUX_POLLOUT;
709 	if (bev & POLLERR)
710 		bits |= LINUX_POLLERR;
711 	if (bev & POLLHUP)
712 		bits |= LINUX_POLLHUP;
713 	if (bev & POLLNVAL)
714 		bits |= LINUX_POLLNVAL;
715 	if (bev & POLLRDNORM)
716 		bits |= LINUX_POLLRDNORM;
717 	if (bev & POLLRDBAND)
718 		bits |= LINUX_POLLRDBAND;
719 	if (bev & POLLWRBAND)
720 		bits |= LINUX_POLLWRBAND;
721 	if (bev & POLLRDHUP)
722 		bits |= LINUX_POLLRDHUP;
723 
724 	*lev = bits;
725 }
726