xref: /freebsd/sys/compat/linux/linux.c (revision 8c2dd68caa963f1900a8228b0732b04f5d530ffa)
1 /*-
2  * Copyright (c) 2015 Dmitry Chagin
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <opt_inet6.h>
31 
32 #include <sys/param.h>
33 #include <sys/systm.h>
34 #include <sys/conf.h>
35 #include <sys/ctype.h>
36 #include <sys/file.h>
37 #include <sys/filedesc.h>
38 #include <sys/jail.h>
39 #include <sys/lock.h>
40 #include <sys/malloc.h>
41 #include <sys/poll.h>
42 #include <sys/proc.h>
43 #include <sys/signalvar.h>
44 #include <sys/socket.h>
45 #include <sys/socketvar.h>
46 
47 #include <net/if.h>
48 #include <net/if_var.h>
49 #include <net/if_dl.h>
50 #include <net/if_types.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 struct futex_list futex_list;
61 struct mtx futex_mtx;			/* protects the futex list */
62 
63 CTASSERT(LINUX_IFNAMSIZ == IFNAMSIZ);
64 
65 static int bsd_to_linux_sigtbl[LINUX_SIGTBLSZ] = {
66 	LINUX_SIGHUP,	/* SIGHUP */
67 	LINUX_SIGINT,	/* SIGINT */
68 	LINUX_SIGQUIT,	/* SIGQUIT */
69 	LINUX_SIGILL,	/* SIGILL */
70 	LINUX_SIGTRAP,	/* SIGTRAP */
71 	LINUX_SIGABRT,	/* SIGABRT */
72 	0,		/* SIGEMT */
73 	LINUX_SIGFPE,	/* SIGFPE */
74 	LINUX_SIGKILL,	/* SIGKILL */
75 	LINUX_SIGBUS,	/* SIGBUS */
76 	LINUX_SIGSEGV,	/* SIGSEGV */
77 	LINUX_SIGSYS,	/* SIGSYS */
78 	LINUX_SIGPIPE,	/* SIGPIPE */
79 	LINUX_SIGALRM,	/* SIGALRM */
80 	LINUX_SIGTERM,	/* SIGTERM */
81 	LINUX_SIGURG,	/* SIGURG */
82 	LINUX_SIGSTOP,	/* SIGSTOP */
83 	LINUX_SIGTSTP,	/* SIGTSTP */
84 	LINUX_SIGCONT,	/* SIGCONT */
85 	LINUX_SIGCHLD,	/* SIGCHLD */
86 	LINUX_SIGTTIN,	/* SIGTTIN */
87 	LINUX_SIGTTOU,	/* SIGTTOU */
88 	LINUX_SIGIO,	/* SIGIO */
89 	LINUX_SIGXCPU,	/* SIGXCPU */
90 	LINUX_SIGXFSZ,	/* SIGXFSZ */
91 	LINUX_SIGVTALRM,/* SIGVTALRM */
92 	LINUX_SIGPROF,	/* SIGPROF */
93 	LINUX_SIGWINCH,	/* SIGWINCH */
94 	0,		/* SIGINFO */
95 	LINUX_SIGUSR1,	/* SIGUSR1 */
96 	LINUX_SIGUSR2	/* SIGUSR2 */
97 };
98 
99 static int linux_to_bsd_sigtbl[LINUX_SIGTBLSZ] = {
100 	SIGHUP,		/* LINUX_SIGHUP */
101 	SIGINT,		/* LINUX_SIGINT */
102 	SIGQUIT,	/* LINUX_SIGQUIT */
103 	SIGILL,		/* LINUX_SIGILL */
104 	SIGTRAP,	/* LINUX_SIGTRAP */
105 	SIGABRT,	/* LINUX_SIGABRT */
106 	SIGBUS,		/* LINUX_SIGBUS */
107 	SIGFPE,		/* LINUX_SIGFPE */
108 	SIGKILL,	/* LINUX_SIGKILL */
109 	SIGUSR1,	/* LINUX_SIGUSR1 */
110 	SIGSEGV,	/* LINUX_SIGSEGV */
111 	SIGUSR2,	/* LINUX_SIGUSR2 */
112 	SIGPIPE,	/* LINUX_SIGPIPE */
113 	SIGALRM,	/* LINUX_SIGALRM */
114 	SIGTERM,	/* LINUX_SIGTERM */
115 	SIGBUS,		/* LINUX_SIGSTKFLT */
116 	SIGCHLD,	/* LINUX_SIGCHLD */
117 	SIGCONT,	/* LINUX_SIGCONT */
118 	SIGSTOP,	/* LINUX_SIGSTOP */
119 	SIGTSTP,	/* LINUX_SIGTSTP */
120 	SIGTTIN,	/* LINUX_SIGTTIN */
121 	SIGTTOU,	/* LINUX_SIGTTOU */
122 	SIGURG,		/* LINUX_SIGURG */
123 	SIGXCPU,	/* LINUX_SIGXCPU */
124 	SIGXFSZ,	/* LINUX_SIGXFSZ */
125 	SIGVTALRM,	/* LINUX_SIGVTALARM */
126 	SIGPROF,	/* LINUX_SIGPROF */
127 	SIGWINCH,	/* LINUX_SIGWINCH */
128 	SIGIO,		/* LINUX_SIGIO */
129 	/*
130 	 * FreeBSD does not have SIGPWR signal, map Linux SIGPWR signal
131 	 * to the first unused FreeBSD signal number. Since Linux supports
132 	 * signals from 1 to 64 we are ok here as our SIGRTMIN = 65.
133 	 */
134 	SIGRTMIN,	/* LINUX_SIGPWR */
135 	SIGSYS		/* LINUX_SIGSYS */
136 };
137 
138 static struct cdev *dev_shm_cdev;
139 static struct cdevsw dev_shm_cdevsw = {
140      .d_version = D_VERSION,
141      .d_name    = "dev_shm",
142 };
143 
144 /*
145  * Map Linux RT signals to the FreeBSD RT signals.
146  */
147 static inline int
148 linux_to_bsd_rt_signal(int sig)
149 {
150 
151 	return (SIGRTMIN + 1 + sig - LINUX_SIGRTMIN);
152 }
153 
154 static inline int
155 bsd_to_linux_rt_signal(int sig)
156 {
157 
158 	return (sig - SIGRTMIN - 1 + LINUX_SIGRTMIN);
159 }
160 
161 int
162 linux_to_bsd_signal(int sig)
163 {
164 
165 	KASSERT(sig > 0 && sig <= LINUX_SIGRTMAX, ("invalid Linux signal %d\n", sig));
166 
167 	if (sig < LINUX_SIGRTMIN)
168 		return (linux_to_bsd_sigtbl[_SIG_IDX(sig)]);
169 
170 	return (linux_to_bsd_rt_signal(sig));
171 }
172 
173 int
174 bsd_to_linux_signal(int sig)
175 {
176 
177 	if (sig <= LINUX_SIGTBLSZ)
178 		return (bsd_to_linux_sigtbl[_SIG_IDX(sig)]);
179 	if (sig == SIGRTMIN)
180 		return (LINUX_SIGPWR);
181 
182 	return (bsd_to_linux_rt_signal(sig));
183 }
184 
185 int
186 linux_to_bsd_sigaltstack(int lsa)
187 {
188 	int bsa = 0;
189 
190 	if (lsa & LINUX_SS_DISABLE)
191 		bsa |= SS_DISABLE;
192 	/*
193 	 * Linux ignores SS_ONSTACK flag for ss
194 	 * parameter while FreeBSD prohibits it.
195 	 */
196 	return (bsa);
197 }
198 
199 int
200 bsd_to_linux_sigaltstack(int bsa)
201 {
202 	int lsa = 0;
203 
204 	if (bsa & SS_DISABLE)
205 		lsa |= LINUX_SS_DISABLE;
206 	if (bsa & SS_ONSTACK)
207 		lsa |= LINUX_SS_ONSTACK;
208 	return (lsa);
209 }
210 
211 void
212 linux_to_bsd_sigset(l_sigset_t *lss, sigset_t *bss)
213 {
214 	int b, l;
215 
216 	SIGEMPTYSET(*bss);
217 	for (l = 1; l <= LINUX_SIGRTMAX; l++) {
218 		if (LINUX_SIGISMEMBER(*lss, l)) {
219 			b = linux_to_bsd_signal(l);
220 			if (b)
221 				SIGADDSET(*bss, b);
222 		}
223 	}
224 }
225 
226 void
227 bsd_to_linux_sigset(sigset_t *bss, l_sigset_t *lss)
228 {
229 	int b, l;
230 
231 	LINUX_SIGEMPTYSET(*lss);
232 	for (b = 1; b <= SIGRTMAX; b++) {
233 		if (SIGISMEMBER(*bss, b)) {
234 			l = bsd_to_linux_signal(b);
235 			if (l)
236 				LINUX_SIGADDSET(*lss, l);
237 		}
238 	}
239 }
240 
241 /*
242  * Translate a Linux interface name to a FreeBSD interface name,
243  * and return the associated ifnet structure
244  * bsdname and lxname need to be least IFNAMSIZ bytes long, but
245  * can point to the same buffer.
246  */
247 struct ifnet *
248 ifname_linux_to_bsd(struct thread *td, const char *lxname, char *bsdname)
249 {
250 	struct ifnet *ifp;
251 	int len, unit;
252 	char *ep;
253 	int index;
254 	bool is_eth, is_lo;
255 
256 	for (len = 0; len < LINUX_IFNAMSIZ; ++len)
257 		if (!isalpha(lxname[len]) || lxname[len] == '\0')
258 			break;
259 	if (len == 0 || len == LINUX_IFNAMSIZ)
260 		return (NULL);
261 	/* Linux loopback interface name is lo (not lo0) */
262 	is_lo = (len == 2 && strncmp(lxname, "lo", len) == 0);
263 	unit = (int)strtoul(lxname + len, &ep, 10);
264 	if ((ep == NULL || ep == lxname + len || ep >= lxname + LINUX_IFNAMSIZ) &&
265 	    is_lo == 0)
266 		return (NULL);
267 	index = 0;
268 	is_eth = (len == 3 && strncmp(lxname, "eth", len) == 0);
269 
270 	CURVNET_SET(TD_TO_VNET(td));
271 	IFNET_RLOCK();
272 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
273 		/*
274 		 * Allow Linux programs to use FreeBSD names. Don't presume
275 		 * we never have an interface named "eth", so don't make
276 		 * the test optional based on is_eth.
277 		 */
278 		if (strncmp(ifp->if_xname, lxname, LINUX_IFNAMSIZ) == 0)
279 			break;
280 		if (is_eth && IFP_IS_ETH(ifp) && unit == index++)
281 			break;
282 		if (is_lo && IFP_IS_LOOP(ifp))
283 			break;
284 	}
285 	IFNET_RUNLOCK();
286 	CURVNET_RESTORE();
287 	if (ifp != NULL && bsdname != NULL)
288 		strlcpy(bsdname, ifp->if_xname, IFNAMSIZ);
289 	return (ifp);
290 }
291 
292 void
293 linux_ifflags(struct ifnet *ifp, short *flags)
294 {
295 	unsigned short fl;
296 
297 	fl = (ifp->if_flags | ifp->if_drv_flags) & 0xffff;
298 	*flags = 0;
299 	if (fl & IFF_UP)
300 		*flags |= LINUX_IFF_UP;
301 	if (fl & IFF_BROADCAST)
302 		*flags |= LINUX_IFF_BROADCAST;
303 	if (fl & IFF_DEBUG)
304 		*flags |= LINUX_IFF_DEBUG;
305 	if (fl & IFF_LOOPBACK)
306 		*flags |= LINUX_IFF_LOOPBACK;
307 	if (fl & IFF_POINTOPOINT)
308 		*flags |= LINUX_IFF_POINTOPOINT;
309 	if (fl & IFF_DRV_RUNNING)
310 		*flags |= LINUX_IFF_RUNNING;
311 	if (fl & IFF_NOARP)
312 		*flags |= LINUX_IFF_NOARP;
313 	if (fl & IFF_PROMISC)
314 		*flags |= LINUX_IFF_PROMISC;
315 	if (fl & IFF_ALLMULTI)
316 		*flags |= LINUX_IFF_ALLMULTI;
317 	if (fl & IFF_MULTICAST)
318 		*flags |= LINUX_IFF_MULTICAST;
319 }
320 
321 int
322 linux_ifhwaddr(struct ifnet *ifp, struct l_sockaddr *lsa)
323 {
324 	struct ifaddr *ifa;
325 	struct sockaddr_dl *sdl;
326 
327 	if (IFP_IS_LOOP(ifp)) {
328 		bzero(lsa, sizeof(*lsa));
329 		lsa->sa_family = LINUX_ARPHRD_LOOPBACK;
330 		return (0);
331 	}
332 
333 	if (!IFP_IS_ETH(ifp))
334 		return (ENOENT);
335 
336 	CK_STAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
337 		sdl = (struct sockaddr_dl*)ifa->ifa_addr;
338 		if (sdl != NULL && (sdl->sdl_family == AF_LINK) &&
339 		    (sdl->sdl_type == IFT_ETHER)) {
340 			bzero(lsa, sizeof(*lsa));
341 			lsa->sa_family = LINUX_ARPHRD_ETHER;
342 			bcopy(LLADDR(sdl), lsa->sa_data, LINUX_IFHWADDRLEN);
343 			return (0);
344 		}
345 	}
346 
347 	return (ENOENT);
348 }
349 
350 int
351 linux_to_bsd_domain(int domain)
352 {
353 
354 	switch (domain) {
355 	case LINUX_AF_UNSPEC:
356 		return (AF_UNSPEC);
357 	case LINUX_AF_UNIX:
358 		return (AF_LOCAL);
359 	case LINUX_AF_INET:
360 		return (AF_INET);
361 	case LINUX_AF_INET6:
362 		return (AF_INET6);
363 	case LINUX_AF_AX25:
364 		return (AF_CCITT);
365 	case LINUX_AF_IPX:
366 		return (AF_IPX);
367 	case LINUX_AF_APPLETALK:
368 		return (AF_APPLETALK);
369 	}
370 	return (-1);
371 }
372 
373 int
374 bsd_to_linux_domain(int domain)
375 {
376 
377 	switch (domain) {
378 	case AF_UNSPEC:
379 		return (LINUX_AF_UNSPEC);
380 	case AF_LOCAL:
381 		return (LINUX_AF_UNIX);
382 	case AF_INET:
383 		return (LINUX_AF_INET);
384 	case AF_INET6:
385 		return (LINUX_AF_INET6);
386 	case AF_CCITT:
387 		return (LINUX_AF_AX25);
388 	case AF_IPX:
389 		return (LINUX_AF_IPX);
390 	case AF_APPLETALK:
391 		return (LINUX_AF_APPLETALK);
392 	}
393 	return (-1);
394 }
395 
396 /*
397  * Based on the fact that:
398  * 1. Native and Linux storage of struct sockaddr
399  * and struct sockaddr_in6 are equal.
400  * 2. On Linux sa_family is the first member of all struct sockaddr.
401  */
402 int
403 bsd_to_linux_sockaddr(const struct sockaddr *sa, struct l_sockaddr **lsa,
404     socklen_t len)
405 {
406 	struct l_sockaddr *kosa;
407 	int error, bdom;
408 
409 	*lsa = NULL;
410 	if (len < 2 || len > UCHAR_MAX)
411 		return (EINVAL);
412 
413 	kosa = malloc(len, M_SONAME, M_WAITOK);
414 	bcopy(sa, kosa, len);
415 
416 	bdom = bsd_to_linux_domain(sa->sa_family);
417 	if (bdom == -1) {
418 		error = EAFNOSUPPORT;
419 		goto out;
420 	}
421 
422 	kosa->sa_family = bdom;
423 	*lsa = kosa;
424 	return (0);
425 
426 out:
427 	free(kosa, M_SONAME);
428 	return (error);
429 }
430 
431 int
432 linux_to_bsd_sockaddr(const struct l_sockaddr *osa, struct sockaddr **sap,
433     socklen_t *len)
434 {
435 	struct sockaddr *sa;
436 	struct l_sockaddr *kosa;
437 #ifdef INET6
438 	struct sockaddr_in6 *sin6;
439 	bool  oldv6size;
440 #endif
441 	char *name;
442 	int salen, bdom, error, hdrlen, namelen;
443 
444 	if (*len < 2 || *len > UCHAR_MAX)
445 		return (EINVAL);
446 
447 	salen = *len;
448 
449 #ifdef INET6
450 	oldv6size = false;
451 	/*
452 	 * Check for old (pre-RFC2553) sockaddr_in6. We may accept it
453 	 * if it's a v4-mapped address, so reserve the proper space
454 	 * for it.
455 	 */
456 	if (salen == sizeof(struct sockaddr_in6) - sizeof(uint32_t)) {
457 		salen += sizeof(uint32_t);
458 		oldv6size = true;
459 	}
460 #endif
461 
462 	kosa = malloc(salen, M_SONAME, M_WAITOK);
463 
464 	if ((error = copyin(osa, kosa, *len)))
465 		goto out;
466 
467 	bdom = linux_to_bsd_domain(kosa->sa_family);
468 	if (bdom == -1) {
469 		error = EAFNOSUPPORT;
470 		goto out;
471 	}
472 
473 #ifdef INET6
474 	/*
475 	 * Older Linux IPv6 code uses obsolete RFC2133 struct sockaddr_in6,
476 	 * which lacks the scope id compared with RFC2553 one. If we detect
477 	 * the situation, reject the address and write a message to system log.
478 	 *
479 	 * Still accept addresses for which the scope id is not used.
480 	 */
481 	if (oldv6size) {
482 		if (bdom == AF_INET6) {
483 			sin6 = (struct sockaddr_in6 *)kosa;
484 			if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr) ||
485 			    (!IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr) &&
486 			     !IN6_IS_ADDR_SITELOCAL(&sin6->sin6_addr) &&
487 			     !IN6_IS_ADDR_V4COMPAT(&sin6->sin6_addr) &&
488 			     !IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr) &&
489 			     !IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))) {
490 				sin6->sin6_scope_id = 0;
491 			} else {
492 				linux_msg(curthread,
493 				    "obsolete pre-RFC2553 sockaddr_in6 rejected");
494 				error = EINVAL;
495 				goto out;
496 			}
497 		} else
498 			salen -= sizeof(uint32_t);
499 	}
500 #endif
501 	if (bdom == AF_INET) {
502 		if (salen < sizeof(struct sockaddr_in)) {
503 			error = EINVAL;
504 			goto out;
505 		}
506 		salen = sizeof(struct sockaddr_in);
507 	}
508 
509 	if (bdom == AF_LOCAL && salen > sizeof(struct sockaddr_un)) {
510 		hdrlen = offsetof(struct sockaddr_un, sun_path);
511 		name = ((struct sockaddr_un *)kosa)->sun_path;
512 		if (*name == '\0') {
513 			/*
514 			 * Linux abstract namespace starts with a NULL byte.
515 			 * XXX We do not support abstract namespace yet.
516 			 */
517 			namelen = strnlen(name + 1, salen - hdrlen - 1) + 1;
518 		} else
519 			namelen = strnlen(name, salen - hdrlen);
520 		salen = hdrlen + namelen;
521 		if (salen > sizeof(struct sockaddr_un)) {
522 			error = ENAMETOOLONG;
523 			goto out;
524 		}
525 	}
526 
527 	sa = (struct sockaddr *)kosa;
528 	sa->sa_family = bdom;
529 	sa->sa_len = salen;
530 
531 	*sap = sa;
532 	*len = salen;
533 	return (0);
534 
535 out:
536 	free(kosa, M_SONAME);
537 	return (error);
538 }
539 
540 void
541 linux_dev_shm_create(void)
542 {
543 	int error;
544 
545 	error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &dev_shm_cdev,
546 	    &dev_shm_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0, "shm/.mountpoint");
547 	if (error != 0) {
548 		printf("%s: failed to create device node, error %d\n",
549 		    __func__, error);
550 	}
551 }
552 
553 void
554 linux_dev_shm_destroy(void)
555 {
556 
557 	destroy_dev(dev_shm_cdev);
558 }
559 
560 int
561 bsd_to_linux_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
562     size_t mapcnt, int no_value)
563 {
564 	int bsd_mask, bsd_value, linux_mask, linux_value;
565 	int linux_ret;
566 	size_t i;
567 	bool applied;
568 
569 	applied = false;
570 	linux_ret = 0;
571 	for (i = 0; i < mapcnt; ++i) {
572 		bsd_mask = bitmap[i].bsd_mask;
573 		bsd_value = bitmap[i].bsd_value;
574 		if (bsd_mask == 0)
575 			bsd_mask = bsd_value;
576 
577 		linux_mask = bitmap[i].linux_mask;
578 		linux_value = bitmap[i].linux_value;
579 		if (linux_mask == 0)
580 			linux_mask = linux_value;
581 
582 		/*
583 		 * If a mask larger than just the value is set, we explicitly
584 		 * want to make sure that only this bit we mapped within that
585 		 * mask is set.
586 		 */
587 		if ((value & bsd_mask) == bsd_value) {
588 			linux_ret = (linux_ret & ~linux_mask) | linux_value;
589 			applied = true;
590 		}
591 	}
592 
593 	if (!applied)
594 		return (no_value);
595 	return (linux_ret);
596 }
597 
598 int
599 linux_to_bsd_bits_(int value, struct bsd_to_linux_bitmap *bitmap,
600     size_t mapcnt, int no_value)
601 {
602 	int bsd_mask, bsd_value, linux_mask, linux_value;
603 	int bsd_ret;
604 	size_t i;
605 	bool applied;
606 
607 	applied = false;
608 	bsd_ret = 0;
609 	for (i = 0; i < mapcnt; ++i) {
610 		bsd_mask = bitmap[i].bsd_mask;
611 		bsd_value = bitmap[i].bsd_value;
612 		if (bsd_mask == 0)
613 			bsd_mask = bsd_value;
614 
615 		linux_mask = bitmap[i].linux_mask;
616 		linux_value = bitmap[i].linux_value;
617 		if (linux_mask == 0)
618 			linux_mask = linux_value;
619 
620 		/*
621 		 * If a mask larger than just the value is set, we explicitly
622 		 * want to make sure that only this bit we mapped within that
623 		 * mask is set.
624 		 */
625 		if ((value & linux_mask) == linux_value) {
626 			bsd_ret = (bsd_ret & ~bsd_mask) | bsd_value;
627 			applied = true;
628 		}
629 	}
630 
631 	if (!applied)
632 		return (no_value);
633 	return (bsd_ret);
634 }
635 
636 void
637 linux_to_bsd_poll_events(struct thread *td, int fd, short lev,
638     short *bev)
639 {
640 	struct proc *p = td->td_proc;
641 	struct filedesc *fdp;
642 	struct file *fp;
643 	int error;
644 	short bits = 0;
645 
646 	if (lev & LINUX_POLLIN)
647 		bits |= POLLIN;
648 	if (lev & LINUX_POLLPRI)
649 		bits |=	POLLPRI;
650 	if (lev & LINUX_POLLOUT)
651 		bits |= POLLOUT;
652 	if (lev & LINUX_POLLERR)
653 		bits |= POLLERR;
654 	if (lev & LINUX_POLLHUP)
655 		bits |= POLLHUP;
656 	if (lev & LINUX_POLLNVAL)
657 		bits |= POLLNVAL;
658 	if (lev & LINUX_POLLRDNORM)
659 		bits |= POLLRDNORM;
660 	if (lev & LINUX_POLLRDBAND)
661 		bits |= POLLRDBAND;
662 	if (lev & LINUX_POLLWRBAND)
663 		bits |= POLLWRBAND;
664 	if (lev & LINUX_POLLWRNORM)
665 		bits |= POLLWRNORM;
666 
667 	if (lev & LINUX_POLLRDHUP) {
668 		/*
669 		 * It seems that the Linux silencly ignores POLLRDHUP
670 		 * on non-socket file descriptors unlike FreeBSD, where
671 		 * events bits is more strictly checked (POLLSTANDARD).
672 		 */
673 		fdp = p->p_fd;
674 		error = fget_unlocked(fdp, 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