uipc_shm.c revision 269495
1175164Sjhb/*-
2225344Srwatson * Copyright (c) 2006, 2011 Robert N. M. Watson
3175164Sjhb * All rights reserved.
4175164Sjhb *
5175164Sjhb * Redistribution and use in source and binary forms, with or without
6175164Sjhb * modification, are permitted provided that the following conditions
7175164Sjhb * are met:
8175164Sjhb * 1. Redistributions of source code must retain the above copyright
9175164Sjhb *    notice, this list of conditions and the following disclaimer.
10175164Sjhb * 2. Redistributions in binary form must reproduce the above copyright
11175164Sjhb *    notice, this list of conditions and the following disclaimer in the
12175164Sjhb *    documentation and/or other materials provided with the distribution.
13175164Sjhb *
14175164Sjhb * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15175164Sjhb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16175164Sjhb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17175164Sjhb * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18175164Sjhb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19175164Sjhb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20175164Sjhb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21175164Sjhb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22175164Sjhb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23175164Sjhb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24175164Sjhb * SUCH DAMAGE.
25175164Sjhb */
26175164Sjhb
27175164Sjhb/*
28175164Sjhb * Support for shared swap-backed anonymous memory objects via
29175164Sjhb * shm_open(2) and shm_unlink(2).  While most of the implementation is
30175164Sjhb * here, vm_mmap.c contains mapping logic changes.
31175164Sjhb *
32175164Sjhb * TODO:
33175164Sjhb *
34225344Srwatson * (1) Need to export data to a userland tool via a sysctl.  Should ipcs(1)
35175164Sjhb *     and ipcrm(1) be expanded or should new tools to manage both POSIX
36175164Sjhb *     kernel semaphores and POSIX shared memory be written?
37175164Sjhb *
38225344Srwatson * (2) Add support for this file type to fstat(1).
39175164Sjhb *
40225344Srwatson * (3) Resource limits?  Does this need its own resource limits or are the
41175164Sjhb *     existing limits in mmap(2) sufficient?
42175164Sjhb */
43175164Sjhb
44175164Sjhb#include <sys/cdefs.h>
45175164Sjhb__FBSDID("$FreeBSD: stable/10/sys/kern/uipc_shm.c 269495 2014-08-04 01:14:27Z kib $");
46175164Sjhb
47223692Sjonathan#include "opt_capsicum.h"
48223692Sjonathan
49175164Sjhb#include <sys/param.h>
50223692Sjonathan#include <sys/capability.h>
51175164Sjhb#include <sys/fcntl.h>
52175164Sjhb#include <sys/file.h>
53175164Sjhb#include <sys/filedesc.h>
54175164Sjhb#include <sys/fnv_hash.h>
55175164Sjhb#include <sys/kernel.h>
56175164Sjhb#include <sys/lock.h>
57175164Sjhb#include <sys/malloc.h>
58175164Sjhb#include <sys/mman.h>
59175164Sjhb#include <sys/mutex.h>
60224914Skib#include <sys/priv.h>
61175164Sjhb#include <sys/proc.h>
62175164Sjhb#include <sys/refcount.h>
63175164Sjhb#include <sys/resourcevar.h>
64248084Sattilio#include <sys/rwlock.h>
65175164Sjhb#include <sys/stat.h>
66175164Sjhb#include <sys/sysctl.h>
67175164Sjhb#include <sys/sysproto.h>
68175164Sjhb#include <sys/systm.h>
69175164Sjhb#include <sys/sx.h>
70175164Sjhb#include <sys/time.h>
71175164Sjhb#include <sys/vnode.h>
72254603Skib#include <sys/unistd.h>
73175164Sjhb
74175164Sjhb#include <security/mac/mac_framework.h>
75175164Sjhb
76175164Sjhb#include <vm/vm.h>
77175164Sjhb#include <vm/vm_param.h>
78175164Sjhb#include <vm/pmap.h>
79228533Sjhb#include <vm/vm_extern.h>
80175164Sjhb#include <vm/vm_map.h>
81228509Sjhb#include <vm/vm_kern.h>
82175164Sjhb#include <vm/vm_object.h>
83175164Sjhb#include <vm/vm_page.h>
84229821Salc#include <vm/vm_pageout.h>
85175164Sjhb#include <vm/vm_pager.h>
86175164Sjhb#include <vm/swap_pager.h>
87175164Sjhb
88175164Sjhbstruct shm_mapping {
89175164Sjhb	char		*sm_path;
90175164Sjhb	Fnv32_t		sm_fnv;
91175164Sjhb	struct shmfd	*sm_shmfd;
92175164Sjhb	LIST_ENTRY(shm_mapping) sm_link;
93175164Sjhb};
94175164Sjhb
95175164Sjhbstatic MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
96175164Sjhbstatic LIST_HEAD(, shm_mapping) *shm_dictionary;
97175164Sjhbstatic struct sx shm_dict_lock;
98175164Sjhbstatic struct mtx shm_timestamp_lock;
99175164Sjhbstatic u_long shm_hash;
100175164Sjhb
101175164Sjhb#define	SHM_HASH(fnv)	(&shm_dictionary[(fnv) & shm_hash])
102175164Sjhb
103175164Sjhbstatic int	shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags);
104175164Sjhbstatic struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode);
105175164Sjhbstatic void	shm_dict_init(void *arg);
106175164Sjhbstatic void	shm_drop(struct shmfd *shmfd);
107175164Sjhbstatic struct shmfd *shm_hold(struct shmfd *shmfd);
108175164Sjhbstatic void	shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
109175164Sjhbstatic struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
110175164Sjhbstatic int	shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
111194766Skibstatic int	shm_dotruncate(struct shmfd *shmfd, off_t length);
112175164Sjhb
113175164Sjhbstatic fo_rdwr_t	shm_read;
114175164Sjhbstatic fo_rdwr_t	shm_write;
115175164Sjhbstatic fo_truncate_t	shm_truncate;
116175164Sjhbstatic fo_ioctl_t	shm_ioctl;
117175164Sjhbstatic fo_poll_t	shm_poll;
118175164Sjhbstatic fo_kqfilter_t	shm_kqfilter;
119175164Sjhbstatic fo_stat_t	shm_stat;
120175164Sjhbstatic fo_close_t	shm_close;
121224914Skibstatic fo_chmod_t	shm_chmod;
122224914Skibstatic fo_chown_t	shm_chown;
123254603Skibstatic fo_seek_t	shm_seek;
124175164Sjhb
125175164Sjhb/* File descriptor operations. */
126175164Sjhbstatic struct fileops shm_ops = {
127175164Sjhb	.fo_read = shm_read,
128175164Sjhb	.fo_write = shm_write,
129175164Sjhb	.fo_truncate = shm_truncate,
130175164Sjhb	.fo_ioctl = shm_ioctl,
131175164Sjhb	.fo_poll = shm_poll,
132175164Sjhb	.fo_kqfilter = shm_kqfilter,
133175164Sjhb	.fo_stat = shm_stat,
134175164Sjhb	.fo_close = shm_close,
135224914Skib	.fo_chmod = shm_chmod,
136224914Skib	.fo_chown = shm_chown,
137255467Skib	.fo_sendfile = vn_sendfile,
138254603Skib	.fo_seek = shm_seek,
139254603Skib	.fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
140175164Sjhb};
141175164Sjhb
142175164SjhbFEATURE(posix_shm, "POSIX shared memory");
143175164Sjhb
144175164Sjhbstatic int
145254601Skibuiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
146254601Skib{
147254601Skib	vm_page_t m;
148254601Skib	vm_pindex_t idx;
149254601Skib	size_t tlen;
150254601Skib	int error, offset, rv;
151254601Skib
152254601Skib	idx = OFF_TO_IDX(uio->uio_offset);
153254601Skib	offset = uio->uio_offset & PAGE_MASK;
154254601Skib	tlen = MIN(PAGE_SIZE - offset, len);
155254601Skib
156254601Skib	VM_OBJECT_WLOCK(obj);
157254601Skib
158254601Skib	/*
159254601Skib	 * Parallel reads of the page content from disk are prevented
160254601Skib	 * by exclusive busy.
161254601Skib	 *
162254601Skib	 * Although the tmpfs vnode lock is held here, it is
163254601Skib	 * nonetheless safe to sleep waiting for a free page.  The
164254601Skib	 * pageout daemon does not need to acquire the tmpfs vnode
165254601Skib	 * lock to page out tobj's pages because tobj is a OBJT_SWAP
166254601Skib	 * type object.
167254601Skib	 */
168254649Skib	m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL);
169254601Skib	if (m->valid != VM_PAGE_BITS_ALL) {
170254601Skib		if (vm_pager_has_page(obj, idx, NULL, NULL)) {
171254601Skib			rv = vm_pager_get_pages(obj, &m, 1, 0);
172254601Skib			m = vm_page_lookup(obj, idx);
173254601Skib			if (m == NULL) {
174254601Skib				printf(
175254601Skib		    "uiomove_object: vm_obj %p idx %jd null lookup rv %d\n",
176254601Skib				    obj, idx, rv);
177254601Skib				VM_OBJECT_WUNLOCK(obj);
178254601Skib				return (EIO);
179254601Skib			}
180254601Skib			if (rv != VM_PAGER_OK) {
181254601Skib				printf(
182254601Skib	    "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
183254601Skib				    obj, idx, m->valid, rv);
184254601Skib				vm_page_lock(m);
185254601Skib				vm_page_free(m);
186254601Skib				vm_page_unlock(m);
187254601Skib				VM_OBJECT_WUNLOCK(obj);
188254601Skib				return (EIO);
189254601Skib			}
190254601Skib		} else
191254601Skib			vm_page_zero_invalid(m, TRUE);
192254601Skib	}
193254601Skib	vm_page_xunbusy(m);
194254601Skib	vm_page_lock(m);
195254601Skib	vm_page_hold(m);
196254601Skib	vm_page_unlock(m);
197254601Skib	VM_OBJECT_WUNLOCK(obj);
198254601Skib	error = uiomove_fromphys(&m, offset, tlen, uio);
199254601Skib	if (uio->uio_rw == UIO_WRITE && error == 0) {
200254601Skib		VM_OBJECT_WLOCK(obj);
201254601Skib		vm_page_dirty(m);
202269495Skib		vm_pager_page_unswapped(m);
203254601Skib		VM_OBJECT_WUNLOCK(obj);
204254601Skib	}
205254601Skib	vm_page_lock(m);
206254601Skib	vm_page_unhold(m);
207254601Skib	if (m->queue == PQ_NONE) {
208254601Skib		vm_page_deactivate(m);
209254601Skib	} else {
210254601Skib		/* Requeue to maintain LRU ordering. */
211254601Skib		vm_page_requeue(m);
212254601Skib	}
213254601Skib	vm_page_unlock(m);
214254601Skib
215254601Skib	return (error);
216254601Skib}
217254601Skib
218254601Skibint
219254601Skibuiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
220254601Skib{
221254601Skib	ssize_t resid;
222254601Skib	size_t len;
223254601Skib	int error;
224254601Skib
225254601Skib	error = 0;
226254601Skib	while ((resid = uio->uio_resid) > 0) {
227254601Skib		if (obj_size <= uio->uio_offset)
228254601Skib			break;
229254601Skib		len = MIN(obj_size - uio->uio_offset, resid);
230254601Skib		if (len == 0)
231254601Skib			break;
232254601Skib		error = uiomove_object_page(obj, len, uio);
233254601Skib		if (error != 0 || resid == uio->uio_resid)
234254601Skib			break;
235254601Skib	}
236254601Skib	return (error);
237254601Skib}
238254601Skib
239254601Skibstatic int
240254603Skibshm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
241254603Skib{
242254603Skib	struct shmfd *shmfd;
243254603Skib	off_t foffset;
244254603Skib	int error;
245254603Skib
246254603Skib	shmfd = fp->f_data;
247254603Skib	foffset = foffset_lock(fp, 0);
248254603Skib	error = 0;
249254603Skib	switch (whence) {
250254603Skib	case L_INCR:
251254603Skib		if (foffset < 0 ||
252254603Skib		    (offset > 0 && foffset > OFF_MAX - offset)) {
253254603Skib			error = EOVERFLOW;
254254603Skib			break;
255254603Skib		}
256254603Skib		offset += foffset;
257254603Skib		break;
258254603Skib	case L_XTND:
259254603Skib		if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
260254603Skib			error = EOVERFLOW;
261254603Skib			break;
262254603Skib		}
263254603Skib		offset += shmfd->shm_size;
264254603Skib		break;
265254603Skib	case L_SET:
266254603Skib		break;
267254603Skib	default:
268254603Skib		error = EINVAL;
269254603Skib	}
270254603Skib	if (error == 0) {
271254603Skib		if (offset < 0 || offset > shmfd->shm_size)
272254603Skib			error = EINVAL;
273254603Skib		else
274254603Skib			*(off_t *)(td->td_retval) = offset;
275254603Skib	}
276254603Skib	foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
277254603Skib	return (error);
278254603Skib}
279254603Skib
280254603Skibstatic int
281175164Sjhbshm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
282175164Sjhb    int flags, struct thread *td)
283175164Sjhb{
284254603Skib	struct shmfd *shmfd;
285254603Skib	void *rl_cookie;
286254603Skib	int error;
287175164Sjhb
288254603Skib	shmfd = fp->f_data;
289254603Skib	foffset_lock_uio(fp, uio, flags);
290254603Skib	rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
291254603Skib	    uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
292254603Skib#ifdef MAC
293254603Skib	error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
294254603Skib	if (error)
295254603Skib		return (error);
296254603Skib#endif
297254603Skib	error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
298254603Skib	rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
299254603Skib	foffset_unlock_uio(fp, uio, flags);
300254603Skib	return (error);
301175164Sjhb}
302175164Sjhb
303175164Sjhbstatic int
304175164Sjhbshm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
305175164Sjhb    int flags, struct thread *td)
306175164Sjhb{
307254603Skib	struct shmfd *shmfd;
308254603Skib	void *rl_cookie;
309254603Skib	int error;
310175164Sjhb
311254603Skib	shmfd = fp->f_data;
312254603Skib#ifdef MAC
313254603Skib	error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
314254603Skib	if (error)
315254603Skib		return (error);
316254603Skib#endif
317254603Skib	foffset_lock_uio(fp, uio, flags);
318254603Skib	if ((flags & FOF_OFFSET) == 0) {
319254603Skib		rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
320254603Skib		    &shmfd->shm_mtx);
321254603Skib	} else {
322254603Skib		rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
323254603Skib		    uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
324254603Skib	}
325254603Skib
326254603Skib	error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
327254603Skib	rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
328254603Skib	foffset_unlock_uio(fp, uio, flags);
329254603Skib	return (error);
330175164Sjhb}
331175164Sjhb
332175164Sjhbstatic int
333175164Sjhbshm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
334175164Sjhb    struct thread *td)
335175164Sjhb{
336175164Sjhb	struct shmfd *shmfd;
337175164Sjhb#ifdef MAC
338175164Sjhb	int error;
339175164Sjhb#endif
340175164Sjhb
341175164Sjhb	shmfd = fp->f_data;
342175164Sjhb#ifdef MAC
343175164Sjhb	error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
344175164Sjhb	if (error)
345175164Sjhb		return (error);
346175164Sjhb#endif
347194766Skib	return (shm_dotruncate(shmfd, length));
348175164Sjhb}
349175164Sjhb
350175164Sjhbstatic int
351175164Sjhbshm_ioctl(struct file *fp, u_long com, void *data,
352175164Sjhb    struct ucred *active_cred, struct thread *td)
353175164Sjhb{
354175164Sjhb
355175164Sjhb	return (EOPNOTSUPP);
356175164Sjhb}
357175164Sjhb
358175164Sjhbstatic int
359175164Sjhbshm_poll(struct file *fp, int events, struct ucred *active_cred,
360175164Sjhb    struct thread *td)
361175164Sjhb{
362175164Sjhb
363175164Sjhb	return (EOPNOTSUPP);
364175164Sjhb}
365175164Sjhb
366175164Sjhbstatic int
367175164Sjhbshm_kqfilter(struct file *fp, struct knote *kn)
368175164Sjhb{
369175164Sjhb
370175164Sjhb	return (EOPNOTSUPP);
371175164Sjhb}
372175164Sjhb
373175164Sjhbstatic int
374175164Sjhbshm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
375175164Sjhb    struct thread *td)
376175164Sjhb{
377175164Sjhb	struct shmfd *shmfd;
378175164Sjhb#ifdef MAC
379175164Sjhb	int error;
380175164Sjhb#endif
381175164Sjhb
382175164Sjhb	shmfd = fp->f_data;
383175164Sjhb
384175164Sjhb#ifdef MAC
385175164Sjhb	error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
386175164Sjhb	if (error)
387175164Sjhb		return (error);
388175164Sjhb#endif
389175164Sjhb
390175164Sjhb	/*
391175164Sjhb	 * Attempt to return sanish values for fstat() on a memory file
392175164Sjhb	 * descriptor.
393175164Sjhb	 */
394175164Sjhb	bzero(sb, sizeof(*sb));
395175164Sjhb	sb->st_blksize = PAGE_SIZE;
396175164Sjhb	sb->st_size = shmfd->shm_size;
397175164Sjhb	sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize;
398224914Skib	mtx_lock(&shm_timestamp_lock);
399205792Sed	sb->st_atim = shmfd->shm_atime;
400205792Sed	sb->st_ctim = shmfd->shm_ctime;
401205792Sed	sb->st_mtim = shmfd->shm_mtime;
402224914Skib	sb->st_birthtim = shmfd->shm_birthtime;
403224914Skib	sb->st_mode = S_IFREG | shmfd->shm_mode;		/* XXX */
404175164Sjhb	sb->st_uid = shmfd->shm_uid;
405175164Sjhb	sb->st_gid = shmfd->shm_gid;
406224914Skib	mtx_unlock(&shm_timestamp_lock);
407175164Sjhb
408175164Sjhb	return (0);
409175164Sjhb}
410175164Sjhb
411175164Sjhbstatic int
412175164Sjhbshm_close(struct file *fp, struct thread *td)
413175164Sjhb{
414175164Sjhb	struct shmfd *shmfd;
415175164Sjhb
416175164Sjhb	shmfd = fp->f_data;
417175164Sjhb	fp->f_data = NULL;
418175164Sjhb	shm_drop(shmfd);
419175164Sjhb
420175164Sjhb	return (0);
421175164Sjhb}
422175164Sjhb
423194766Skibstatic int
424175164Sjhbshm_dotruncate(struct shmfd *shmfd, off_t length)
425175164Sjhb{
426175164Sjhb	vm_object_t object;
427229821Salc	vm_page_t m, ma[1];
428229821Salc	vm_pindex_t idx, nobjsize;
429194766Skib	vm_ooffset_t delta;
430229821Salc	int base, rv;
431175164Sjhb
432175164Sjhb	object = shmfd->shm_object;
433248084Sattilio	VM_OBJECT_WLOCK(object);
434175164Sjhb	if (length == shmfd->shm_size) {
435248084Sattilio		VM_OBJECT_WUNLOCK(object);
436194766Skib		return (0);
437175164Sjhb	}
438175164Sjhb	nobjsize = OFF_TO_IDX(length + PAGE_MASK);
439175164Sjhb
440175164Sjhb	/* Are we shrinking?  If so, trim the end. */
441175164Sjhb	if (length < shmfd->shm_size) {
442228509Sjhb		/*
443228509Sjhb		 * Disallow any requests to shrink the size if this
444228509Sjhb		 * object is mapped into the kernel.
445228509Sjhb		 */
446228509Sjhb		if (shmfd->shm_kmappings > 0) {
447248084Sattilio			VM_OBJECT_WUNLOCK(object);
448228509Sjhb			return (EBUSY);
449228509Sjhb		}
450229821Salc
451229821Salc		/*
452229821Salc		 * Zero the truncated part of the last page.
453229821Salc		 */
454229821Salc		base = length & PAGE_MASK;
455229821Salc		if (base != 0) {
456229821Salc			idx = OFF_TO_IDX(length);
457229821Salcretry:
458229821Salc			m = vm_page_lookup(object, idx);
459229821Salc			if (m != NULL) {
460254138Sattilio				if (vm_page_sleep_if_busy(m, "shmtrc"))
461229821Salc					goto retry;
462229821Salc			} else if (vm_pager_has_page(object, idx, NULL, NULL)) {
463229821Salc				m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL);
464229821Salc				if (m == NULL) {
465248084Sattilio					VM_OBJECT_WUNLOCK(object);
466229821Salc					VM_WAIT;
467248084Sattilio					VM_OBJECT_WLOCK(object);
468229821Salc					goto retry;
469229821Salc				} else if (m->valid != VM_PAGE_BITS_ALL) {
470229821Salc					ma[0] = m;
471229821Salc					rv = vm_pager_get_pages(object, ma, 1,
472229821Salc					    0);
473229821Salc					m = vm_page_lookup(object, idx);
474229821Salc				} else
475229821Salc					/* A cached page was reactivated. */
476229821Salc					rv = VM_PAGER_OK;
477229821Salc				vm_page_lock(m);
478229821Salc				if (rv == VM_PAGER_OK) {
479229821Salc					vm_page_deactivate(m);
480229821Salc					vm_page_unlock(m);
481254138Sattilio					vm_page_xunbusy(m);
482229821Salc				} else {
483229821Salc					vm_page_free(m);
484229821Salc					vm_page_unlock(m);
485248084Sattilio					VM_OBJECT_WUNLOCK(object);
486229821Salc					return (EIO);
487229821Salc				}
488229821Salc			}
489229821Salc			if (m != NULL) {
490229821Salc				pmap_zero_page_area(m, base, PAGE_SIZE - base);
491229821Salc				KASSERT(m->valid == VM_PAGE_BITS_ALL,
492229821Salc				    ("shm_dotruncate: page %p is invalid", m));
493229821Salc				vm_page_dirty(m);
494229821Salc				vm_pager_page_unswapped(m);
495229821Salc			}
496229821Salc		}
497194766Skib		delta = ptoa(object->size - nobjsize);
498194766Skib
499175164Sjhb		/* Toss in memory pages. */
500175164Sjhb		if (nobjsize < object->size)
501175164Sjhb			vm_object_page_remove(object, nobjsize, object->size,
502223677Salc			    0);
503175164Sjhb
504175164Sjhb		/* Toss pages from swap. */
505175164Sjhb		if (object->type == OBJT_SWAP)
506194766Skib			swap_pager_freespace(object, nobjsize, delta);
507175164Sjhb
508194766Skib		/* Free the swap accounted for shm */
509216128Strasz		swap_release_by_cred(delta, object->cred);
510194766Skib		object->charge -= delta;
511194766Skib	} else {
512194766Skib		/* Attempt to reserve the swap */
513194766Skib		delta = ptoa(nobjsize - object->size);
514216128Strasz		if (!swap_reserve_by_cred(delta, object->cred)) {
515248084Sattilio			VM_OBJECT_WUNLOCK(object);
516194766Skib			return (ENOMEM);
517194766Skib		}
518194766Skib		object->charge += delta;
519175164Sjhb	}
520175164Sjhb	shmfd->shm_size = length;
521175164Sjhb	mtx_lock(&shm_timestamp_lock);
522175164Sjhb	vfs_timestamp(&shmfd->shm_ctime);
523175164Sjhb	shmfd->shm_mtime = shmfd->shm_ctime;
524175164Sjhb	mtx_unlock(&shm_timestamp_lock);
525175164Sjhb	object->size = nobjsize;
526248084Sattilio	VM_OBJECT_WUNLOCK(object);
527194766Skib	return (0);
528175164Sjhb}
529175164Sjhb
530175164Sjhb/*
531175164Sjhb * shmfd object management including creation and reference counting
532175164Sjhb * routines.
533175164Sjhb */
534175164Sjhbstatic struct shmfd *
535175164Sjhbshm_alloc(struct ucred *ucred, mode_t mode)
536175164Sjhb{
537175164Sjhb	struct shmfd *shmfd;
538175164Sjhb
539175164Sjhb	shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
540175164Sjhb	shmfd->shm_size = 0;
541175164Sjhb	shmfd->shm_uid = ucred->cr_uid;
542175164Sjhb	shmfd->shm_gid = ucred->cr_gid;
543175164Sjhb	shmfd->shm_mode = mode;
544175164Sjhb	shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
545194766Skib	    shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
546175164Sjhb	KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
547248084Sattilio	VM_OBJECT_WLOCK(shmfd->shm_object);
548178181Salc	vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
549178181Salc	vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT);
550248084Sattilio	VM_OBJECT_WUNLOCK(shmfd->shm_object);
551175164Sjhb	vfs_timestamp(&shmfd->shm_birthtime);
552175164Sjhb	shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
553175164Sjhb	    shmfd->shm_birthtime;
554175164Sjhb	refcount_init(&shmfd->shm_refs, 1);
555254603Skib	mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
556254603Skib	rangelock_init(&shmfd->shm_rl);
557175164Sjhb#ifdef MAC
558175164Sjhb	mac_posixshm_init(shmfd);
559175164Sjhb	mac_posixshm_create(ucred, shmfd);
560175164Sjhb#endif
561175164Sjhb
562175164Sjhb	return (shmfd);
563175164Sjhb}
564175164Sjhb
565175164Sjhbstatic struct shmfd *
566175164Sjhbshm_hold(struct shmfd *shmfd)
567175164Sjhb{
568175164Sjhb
569175164Sjhb	refcount_acquire(&shmfd->shm_refs);
570175164Sjhb	return (shmfd);
571175164Sjhb}
572175164Sjhb
573175164Sjhbstatic void
574175164Sjhbshm_drop(struct shmfd *shmfd)
575175164Sjhb{
576175164Sjhb
577175164Sjhb	if (refcount_release(&shmfd->shm_refs)) {
578175164Sjhb#ifdef MAC
579175164Sjhb		mac_posixshm_destroy(shmfd);
580175164Sjhb#endif
581254603Skib		rangelock_destroy(&shmfd->shm_rl);
582254603Skib		mtx_destroy(&shmfd->shm_mtx);
583175164Sjhb		vm_object_deallocate(shmfd->shm_object);
584175164Sjhb		free(shmfd, M_SHMFD);
585175164Sjhb	}
586175164Sjhb}
587175164Sjhb
588175164Sjhb/*
589175164Sjhb * Determine if the credentials have sufficient permissions for a
590175164Sjhb * specified combination of FREAD and FWRITE.
591175164Sjhb */
592175164Sjhbstatic int
593175164Sjhbshm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
594175164Sjhb{
595184413Strasz	accmode_t accmode;
596224914Skib	int error;
597175164Sjhb
598184413Strasz	accmode = 0;
599175164Sjhb	if (flags & FREAD)
600184413Strasz		accmode |= VREAD;
601175164Sjhb	if (flags & FWRITE)
602184413Strasz		accmode |= VWRITE;
603224914Skib	mtx_lock(&shm_timestamp_lock);
604224914Skib	error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
605224914Skib	    accmode, ucred, NULL);
606224914Skib	mtx_unlock(&shm_timestamp_lock);
607224914Skib	return (error);
608175164Sjhb}
609175164Sjhb
610175164Sjhb/*
611175164Sjhb * Dictionary management.  We maintain an in-kernel dictionary to map
612175164Sjhb * paths to shmfd objects.  We use the FNV hash on the path to store
613175164Sjhb * the mappings in a hash table.
614175164Sjhb */
615175164Sjhbstatic void
616175164Sjhbshm_dict_init(void *arg)
617175164Sjhb{
618175164Sjhb
619175164Sjhb	mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
620175164Sjhb	sx_init(&shm_dict_lock, "shm dictionary");
621175164Sjhb	shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
622175164Sjhb}
623175164SjhbSYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL);
624175164Sjhb
625175164Sjhbstatic struct shmfd *
626175164Sjhbshm_lookup(char *path, Fnv32_t fnv)
627175164Sjhb{
628175164Sjhb	struct shm_mapping *map;
629175164Sjhb
630175164Sjhb	LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
631175164Sjhb		if (map->sm_fnv != fnv)
632175164Sjhb			continue;
633175164Sjhb		if (strcmp(map->sm_path, path) == 0)
634175164Sjhb			return (map->sm_shmfd);
635175164Sjhb	}
636175164Sjhb
637175164Sjhb	return (NULL);
638175164Sjhb}
639175164Sjhb
640175164Sjhbstatic void
641175164Sjhbshm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
642175164Sjhb{
643175164Sjhb	struct shm_mapping *map;
644175164Sjhb
645175164Sjhb	map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
646175164Sjhb	map->sm_path = path;
647175164Sjhb	map->sm_fnv = fnv;
648175164Sjhb	map->sm_shmfd = shm_hold(shmfd);
649233760Sjhb	shmfd->shm_path = path;
650175164Sjhb	LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
651175164Sjhb}
652175164Sjhb
653175164Sjhbstatic int
654175164Sjhbshm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
655175164Sjhb{
656175164Sjhb	struct shm_mapping *map;
657175164Sjhb	int error;
658175164Sjhb
659175164Sjhb	LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
660175164Sjhb		if (map->sm_fnv != fnv)
661175164Sjhb			continue;
662175164Sjhb		if (strcmp(map->sm_path, path) == 0) {
663175164Sjhb#ifdef MAC
664175164Sjhb			error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
665175164Sjhb			if (error)
666175164Sjhb				return (error);
667175164Sjhb#endif
668175164Sjhb			error = shm_access(map->sm_shmfd, ucred,
669175164Sjhb			    FREAD | FWRITE);
670175164Sjhb			if (error)
671175164Sjhb				return (error);
672233760Sjhb			map->sm_shmfd->shm_path = NULL;
673175164Sjhb			LIST_REMOVE(map, sm_link);
674175164Sjhb			shm_drop(map->sm_shmfd);
675175164Sjhb			free(map->sm_path, M_SHMFD);
676175164Sjhb			free(map, M_SHMFD);
677175164Sjhb			return (0);
678175164Sjhb		}
679175164Sjhb	}
680175164Sjhb
681175164Sjhb	return (ENOENT);
682175164Sjhb}
683175164Sjhb
684175164Sjhb/* System calls. */
685175164Sjhbint
686225617Skmacysys_shm_open(struct thread *td, struct shm_open_args *uap)
687175164Sjhb{
688175164Sjhb	struct filedesc *fdp;
689175164Sjhb	struct shmfd *shmfd;
690175164Sjhb	struct file *fp;
691175164Sjhb	char *path;
692175164Sjhb	Fnv32_t fnv;
693175164Sjhb	mode_t cmode;
694175164Sjhb	int fd, error;
695175164Sjhb
696223692Sjonathan#ifdef CAPABILITY_MODE
697223692Sjonathan	/*
698223692Sjonathan	 * shm_open(2) is only allowed for anonymous objects.
699223692Sjonathan	 */
700223692Sjonathan	if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON))
701223692Sjonathan		return (ECAPMODE);
702223692Sjonathan#endif
703223692Sjonathan
704175164Sjhb	if ((uap->flags & O_ACCMODE) != O_RDONLY &&
705175164Sjhb	    (uap->flags & O_ACCMODE) != O_RDWR)
706175164Sjhb		return (EINVAL);
707175164Sjhb
708261329Srmh	if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
709175164Sjhb		return (EINVAL);
710175164Sjhb
711175164Sjhb	fdp = td->td_proc->p_fd;
712175164Sjhb	cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
713175164Sjhb
714249233Sjilles	error = falloc(td, &fp, &fd, O_CLOEXEC);
715175164Sjhb	if (error)
716175164Sjhb		return (error);
717175164Sjhb
718175164Sjhb	/* A SHM_ANON path pointer creates an anonymous object. */
719175164Sjhb	if (uap->path == SHM_ANON) {
720175164Sjhb		/* A read-only anonymous object is pointless. */
721175164Sjhb		if ((uap->flags & O_ACCMODE) == O_RDONLY) {
722175164Sjhb			fdclose(fdp, fp, fd, td);
723175164Sjhb			fdrop(fp, td);
724175164Sjhb			return (EINVAL);
725175164Sjhb		}
726175164Sjhb		shmfd = shm_alloc(td->td_ucred, cmode);
727175164Sjhb	} else {
728175164Sjhb		path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
729175164Sjhb		error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
730175164Sjhb
731175164Sjhb		/* Require paths to start with a '/' character. */
732175164Sjhb		if (error == 0 && path[0] != '/')
733175164Sjhb			error = EINVAL;
734175164Sjhb		if (error) {
735175164Sjhb			fdclose(fdp, fp, fd, td);
736175164Sjhb			fdrop(fp, td);
737175164Sjhb			free(path, M_SHMFD);
738175164Sjhb			return (error);
739175164Sjhb		}
740175164Sjhb
741175164Sjhb		fnv = fnv_32_str(path, FNV1_32_INIT);
742175164Sjhb		sx_xlock(&shm_dict_lock);
743175164Sjhb		shmfd = shm_lookup(path, fnv);
744175164Sjhb		if (shmfd == NULL) {
745175164Sjhb			/* Object does not yet exist, create it if requested. */
746175164Sjhb			if (uap->flags & O_CREAT) {
747225344Srwatson#ifdef MAC
748225344Srwatson				error = mac_posixshm_check_create(td->td_ucred,
749225344Srwatson				    path);
750225344Srwatson				if (error == 0) {
751225344Srwatson#endif
752225344Srwatson					shmfd = shm_alloc(td->td_ucred, cmode);
753225344Srwatson					shm_insert(path, fnv, shmfd);
754225344Srwatson#ifdef MAC
755225344Srwatson				}
756225344Srwatson#endif
757175164Sjhb			} else {
758175164Sjhb				free(path, M_SHMFD);
759175164Sjhb				error = ENOENT;
760175164Sjhb			}
761175164Sjhb		} else {
762175164Sjhb			/*
763175164Sjhb			 * Object already exists, obtain a new
764175164Sjhb			 * reference if requested and permitted.
765175164Sjhb			 */
766175164Sjhb			free(path, M_SHMFD);
767175164Sjhb			if ((uap->flags & (O_CREAT | O_EXCL)) ==
768175164Sjhb			    (O_CREAT | O_EXCL))
769175164Sjhb				error = EEXIST;
770175164Sjhb			else {
771175164Sjhb#ifdef MAC
772175164Sjhb				error = mac_posixshm_check_open(td->td_ucred,
773225344Srwatson				    shmfd, FFLAGS(uap->flags & O_ACCMODE));
774175164Sjhb				if (error == 0)
775175164Sjhb#endif
776175164Sjhb				error = shm_access(shmfd, td->td_ucred,
777175164Sjhb				    FFLAGS(uap->flags & O_ACCMODE));
778175164Sjhb			}
779175164Sjhb
780175164Sjhb			/*
781175164Sjhb			 * Truncate the file back to zero length if
782175164Sjhb			 * O_TRUNC was specified and the object was
783175164Sjhb			 * opened with read/write.
784175164Sjhb			 */
785175164Sjhb			if (error == 0 &&
786175164Sjhb			    (uap->flags & (O_ACCMODE | O_TRUNC)) ==
787175164Sjhb			    (O_RDWR | O_TRUNC)) {
788175164Sjhb#ifdef MAC
789175164Sjhb				error = mac_posixshm_check_truncate(
790175164Sjhb					td->td_ucred, fp->f_cred, shmfd);
791175164Sjhb				if (error == 0)
792175164Sjhb#endif
793175164Sjhb					shm_dotruncate(shmfd, 0);
794175164Sjhb			}
795175164Sjhb			if (error == 0)
796175164Sjhb				shm_hold(shmfd);
797175164Sjhb		}
798175164Sjhb		sx_xunlock(&shm_dict_lock);
799175164Sjhb
800175164Sjhb		if (error) {
801175164Sjhb			fdclose(fdp, fp, fd, td);
802175164Sjhb			fdrop(fp, td);
803175164Sjhb			return (error);
804175164Sjhb		}
805175164Sjhb	}
806175164Sjhb
807175164Sjhb	finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
808175164Sjhb
809175164Sjhb	td->td_retval[0] = fd;
810175164Sjhb	fdrop(fp, td);
811175164Sjhb
812175164Sjhb	return (0);
813175164Sjhb}
814175164Sjhb
815175164Sjhbint
816225617Skmacysys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
817175164Sjhb{
818175164Sjhb	char *path;
819175164Sjhb	Fnv32_t fnv;
820175164Sjhb	int error;
821175164Sjhb
822175164Sjhb	path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
823175164Sjhb	error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
824175164Sjhb	if (error) {
825175164Sjhb		free(path, M_TEMP);
826175164Sjhb		return (error);
827175164Sjhb	}
828175164Sjhb
829175164Sjhb	fnv = fnv_32_str(path, FNV1_32_INIT);
830175164Sjhb	sx_xlock(&shm_dict_lock);
831175164Sjhb	error = shm_remove(path, fnv, td->td_ucred);
832175164Sjhb	sx_xunlock(&shm_dict_lock);
833175164Sjhb	free(path, M_TEMP);
834175164Sjhb
835175164Sjhb	return (error);
836175164Sjhb}
837175164Sjhb
838175164Sjhb/*
839175164Sjhb * mmap() helper to validate mmap() requests against shm object state
840175164Sjhb * and give mmap() the vm_object to use for the mapping.
841175164Sjhb */
842175164Sjhbint
843175164Sjhbshm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff,
844175164Sjhb    vm_object_t *obj)
845175164Sjhb{
846175164Sjhb
847175164Sjhb	/*
848175164Sjhb	 * XXXRW: This validation is probably insufficient, and subject to
849175164Sjhb	 * sign errors.  It should be fixed.
850175164Sjhb	 */
851185533Skan	if (foff >= shmfd->shm_size ||
852185533Skan	    foff + objsize > round_page(shmfd->shm_size))
853175164Sjhb		return (EINVAL);
854175164Sjhb
855175164Sjhb	mtx_lock(&shm_timestamp_lock);
856175164Sjhb	vfs_timestamp(&shmfd->shm_atime);
857175164Sjhb	mtx_unlock(&shm_timestamp_lock);
858175164Sjhb	vm_object_reference(shmfd->shm_object);
859175164Sjhb	*obj = shmfd->shm_object;
860175164Sjhb	return (0);
861175164Sjhb}
862224914Skib
863224914Skibstatic int
864224914Skibshm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
865224914Skib    struct thread *td)
866224914Skib{
867224914Skib	struct shmfd *shmfd;
868224914Skib	int error;
869224914Skib
870224914Skib	error = 0;
871224914Skib	shmfd = fp->f_data;
872224914Skib	mtx_lock(&shm_timestamp_lock);
873224914Skib	/*
874224914Skib	 * SUSv4 says that x bits of permission need not be affected.
875224914Skib	 * Be consistent with our shm_open there.
876224914Skib	 */
877224914Skib#ifdef MAC
878224914Skib	error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
879224914Skib	if (error != 0)
880224914Skib		goto out;
881224914Skib#endif
882224914Skib	error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
883224914Skib	    shmfd->shm_gid, VADMIN, active_cred, NULL);
884224914Skib	if (error != 0)
885224914Skib		goto out;
886224914Skib	shmfd->shm_mode = mode & ACCESSPERMS;
887224914Skibout:
888224914Skib	mtx_unlock(&shm_timestamp_lock);
889224914Skib	return (error);
890224914Skib}
891224914Skib
892224914Skibstatic int
893224914Skibshm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
894224914Skib    struct thread *td)
895224914Skib{
896224914Skib	struct shmfd *shmfd;
897224914Skib	int error;
898224914Skib
899224935Skib	error = 0;
900224914Skib	shmfd = fp->f_data;
901224914Skib	mtx_lock(&shm_timestamp_lock);
902224914Skib#ifdef MAC
903224914Skib	error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
904224914Skib	if (error != 0)
905224914Skib		goto out;
906224914Skib#endif
907224914Skib	if (uid == (uid_t)-1)
908224914Skib		uid = shmfd->shm_uid;
909224914Skib	if (gid == (gid_t)-1)
910224914Skib                 gid = shmfd->shm_gid;
911224914Skib	if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
912224914Skib	    (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
913224914Skib	    (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
914224914Skib		goto out;
915224914Skib	shmfd->shm_uid = uid;
916224914Skib	shmfd->shm_gid = gid;
917224914Skibout:
918224914Skib	mtx_unlock(&shm_timestamp_lock);
919224914Skib	return (error);
920224914Skib}
921228509Sjhb
922228509Sjhb/*
923228509Sjhb * Helper routines to allow the backing object of a shared memory file
924228509Sjhb * descriptor to be mapped in the kernel.
925228509Sjhb */
926228509Sjhbint
927228509Sjhbshm_map(struct file *fp, size_t size, off_t offset, void **memp)
928228509Sjhb{
929228509Sjhb	struct shmfd *shmfd;
930228509Sjhb	vm_offset_t kva, ofs;
931228509Sjhb	vm_object_t obj;
932228509Sjhb	int rv;
933228509Sjhb
934228509Sjhb	if (fp->f_type != DTYPE_SHM)
935228509Sjhb		return (EINVAL);
936228509Sjhb	shmfd = fp->f_data;
937228509Sjhb	obj = shmfd->shm_object;
938248084Sattilio	VM_OBJECT_WLOCK(obj);
939228509Sjhb	/*
940228509Sjhb	 * XXXRW: This validation is probably insufficient, and subject to
941228509Sjhb	 * sign errors.  It should be fixed.
942228509Sjhb	 */
943228509Sjhb	if (offset >= shmfd->shm_size ||
944228509Sjhb	    offset + size > round_page(shmfd->shm_size)) {
945248084Sattilio		VM_OBJECT_WUNLOCK(obj);
946228509Sjhb		return (EINVAL);
947228509Sjhb	}
948228509Sjhb
949228509Sjhb	shmfd->shm_kmappings++;
950228509Sjhb	vm_object_reference_locked(obj);
951248084Sattilio	VM_OBJECT_WUNLOCK(obj);
952228509Sjhb
953228509Sjhb	/* Map the object into the kernel_map and wire it. */
954228509Sjhb	kva = vm_map_min(kernel_map);
955228509Sjhb	ofs = offset & PAGE_MASK;
956228509Sjhb	offset = trunc_page(offset);
957228509Sjhb	size = round_page(size + ofs);
958255426Sjhb	rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
959253620Sjhb	    VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
960228509Sjhb	    VM_PROT_READ | VM_PROT_WRITE, 0);
961228509Sjhb	if (rv == KERN_SUCCESS) {
962228509Sjhb		rv = vm_map_wire(kernel_map, kva, kva + size,
963228509Sjhb		    VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
964228509Sjhb		if (rv == KERN_SUCCESS) {
965228509Sjhb			*memp = (void *)(kva + ofs);
966228509Sjhb			return (0);
967228509Sjhb		}
968228509Sjhb		vm_map_remove(kernel_map, kva, kva + size);
969228509Sjhb	} else
970228509Sjhb		vm_object_deallocate(obj);
971228509Sjhb
972228509Sjhb	/* On failure, drop our mapping reference. */
973248084Sattilio	VM_OBJECT_WLOCK(obj);
974228509Sjhb	shmfd->shm_kmappings--;
975248084Sattilio	VM_OBJECT_WUNLOCK(obj);
976228509Sjhb
977228533Sjhb	return (vm_mmap_to_errno(rv));
978228509Sjhb}
979228509Sjhb
980228509Sjhb/*
981228509Sjhb * We require the caller to unmap the entire entry.  This allows us to
982228509Sjhb * safely decrement shm_kmappings when a mapping is removed.
983228509Sjhb */
984228509Sjhbint
985228509Sjhbshm_unmap(struct file *fp, void *mem, size_t size)
986228509Sjhb{
987228509Sjhb	struct shmfd *shmfd;
988228509Sjhb	vm_map_entry_t entry;
989228509Sjhb	vm_offset_t kva, ofs;
990228509Sjhb	vm_object_t obj;
991228509Sjhb	vm_pindex_t pindex;
992228509Sjhb	vm_prot_t prot;
993228509Sjhb	boolean_t wired;
994228509Sjhb	vm_map_t map;
995228509Sjhb	int rv;
996228509Sjhb
997228509Sjhb	if (fp->f_type != DTYPE_SHM)
998228509Sjhb		return (EINVAL);
999228509Sjhb	shmfd = fp->f_data;
1000228509Sjhb	kva = (vm_offset_t)mem;
1001228509Sjhb	ofs = kva & PAGE_MASK;
1002228509Sjhb	kva = trunc_page(kva);
1003228509Sjhb	size = round_page(size + ofs);
1004228509Sjhb	map = kernel_map;
1005228509Sjhb	rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1006228509Sjhb	    &obj, &pindex, &prot, &wired);
1007228509Sjhb	if (rv != KERN_SUCCESS)
1008228509Sjhb		return (EINVAL);
1009228509Sjhb	if (entry->start != kva || entry->end != kva + size) {
1010228509Sjhb		vm_map_lookup_done(map, entry);
1011228509Sjhb		return (EINVAL);
1012228509Sjhb	}
1013228509Sjhb	vm_map_lookup_done(map, entry);
1014228509Sjhb	if (obj != shmfd->shm_object)
1015228509Sjhb		return (EINVAL);
1016228509Sjhb	vm_map_remove(map, kva, kva + size);
1017248084Sattilio	VM_OBJECT_WLOCK(obj);
1018228509Sjhb	KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1019228509Sjhb	shmfd->shm_kmappings--;
1020248084Sattilio	VM_OBJECT_WUNLOCK(obj);
1021228509Sjhb	return (0);
1022228509Sjhb}
1023233760Sjhb
1024233760Sjhbvoid
1025233760Sjhbshm_path(struct shmfd *shmfd, char *path, size_t size)
1026233760Sjhb{
1027233760Sjhb
1028233760Sjhb	if (shmfd->shm_path == NULL)
1029233760Sjhb		return;
1030233760Sjhb	sx_slock(&shm_dict_lock);
1031233760Sjhb	if (shmfd->shm_path != NULL)
1032233760Sjhb		strlcpy(path, shmfd->shm_path, size);
1033233760Sjhb	sx_sunlock(&shm_dict_lock);
1034233760Sjhb}
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