2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
7 * Portions of this software were developed by BAE Systems, the University of
8 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
9 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
10 * Computing (TC) research program.
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * Support for shared swap-backed anonymous memory objects via
36 * shm_open(2) and shm_unlink(2). While most of the implementation is
37 * here, vm_mmap.c contains mapping logic changes.
41 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1)
42 * and ipcrm(1) be expanded or should new tools to manage both POSIX
43 * kernel semaphores and POSIX shared memory be written?
45 * (2) Add support for this file type to fstat(1).
47 * (3) Resource limits? Does this need its own resource limits or are the
48 * existing limits in mmap(2) sufficient?
51 #include <sys/cdefs.h>
52 __FBSDID("$FreeBSD$");
54 #include "opt_capsicum.h"
55 #include "opt_ktrace.h"
57 #include <sys/param.h>
58 #include <sys/capsicum.h>
60 #include <sys/fcntl.h>
62 #include <sys/filedesc.h>
63 #include <sys/filio.h>
64 #include <sys/fnv_hash.h>
65 #include <sys/kernel.h>
67 #include <sys/signal.h>
69 #include <sys/ktrace.h>
71 #include <sys/malloc.h>
73 #include <sys/mutex.h>
76 #include <sys/refcount.h>
77 #include <sys/resourcevar.h>
78 #include <sys/rwlock.h>
80 #include <sys/syscallsubr.h>
81 #include <sys/sysctl.h>
82 #include <sys/sysproto.h>
83 #include <sys/systm.h>
86 #include <sys/vnode.h>
87 #include <sys/unistd.h>
90 #include <security/audit/audit.h>
91 #include <security/mac/mac_framework.h>
94 #include <vm/vm_param.h>
96 #include <vm/vm_extern.h>
97 #include <vm/vm_map.h>
98 #include <vm/vm_kern.h>
99 #include <vm/vm_object.h>
100 #include <vm/vm_page.h>
101 #include <vm/vm_pageout.h>
102 #include <vm/vm_pager.h>
103 #include <vm/swap_pager.h>
108 struct shmfd *sm_shmfd;
109 LIST_ENTRY(shm_mapping) sm_link;
112 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
113 static LIST_HEAD(, shm_mapping) *shm_dictionary;
114 static struct sx shm_dict_lock;
115 static struct mtx shm_timestamp_lock;
116 static u_long shm_hash;
117 static struct unrhdr64 shm_ino_unr;
118 static dev_t shm_dev_ino;
120 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
122 static void shm_init(void *arg);
123 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
124 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
125 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
127 static fo_rdwr_t shm_read;
128 static fo_rdwr_t shm_write;
129 static fo_truncate_t shm_truncate;
130 static fo_ioctl_t shm_ioctl;
131 static fo_stat_t shm_stat;
132 static fo_close_t shm_close;
133 static fo_chmod_t shm_chmod;
134 static fo_chown_t shm_chown;
135 static fo_seek_t shm_seek;
136 static fo_fill_kinfo_t shm_fill_kinfo;
137 static fo_mmap_t shm_mmap;
139 /* File descriptor operations. */
140 struct fileops shm_ops = {
142 .fo_write = shm_write,
143 .fo_truncate = shm_truncate,
144 .fo_ioctl = shm_ioctl,
145 .fo_poll = invfo_poll,
146 .fo_kqfilter = invfo_kqfilter,
148 .fo_close = shm_close,
149 .fo_chmod = shm_chmod,
150 .fo_chown = shm_chown,
151 .fo_sendfile = vn_sendfile,
153 .fo_fill_kinfo = shm_fill_kinfo,
155 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
158 FEATURE(posix_shm, "POSIX shared memory");
161 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
166 int error, offset, rv;
168 idx = OFF_TO_IDX(uio->uio_offset);
169 offset = uio->uio_offset & PAGE_MASK;
170 tlen = MIN(PAGE_SIZE - offset, len);
172 VM_OBJECT_WLOCK(obj);
175 * Read I/O without either a corresponding resident page or swap
176 * page: use zero_region. This is intended to avoid instantiating
177 * pages on read from a sparse region.
179 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL &&
180 !vm_pager_has_page(obj, idx, NULL, NULL)) {
181 VM_OBJECT_WUNLOCK(obj);
182 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
186 * Parallel reads of the page content from disk are prevented
189 * Although the tmpfs vnode lock is held here, it is
190 * nonetheless safe to sleep waiting for a free page. The
191 * pageout daemon does not need to acquire the tmpfs vnode
192 * lock to page out tobj's pages because tobj is a OBJT_SWAP
195 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
196 if (m->valid != VM_PAGE_BITS_ALL) {
198 if (vm_pager_has_page(obj, idx, NULL, NULL)) {
199 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
200 if (rv != VM_PAGER_OK) {
202 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
203 obj, idx, m->valid, rv);
207 VM_OBJECT_WUNLOCK(obj);
211 vm_page_zero_invalid(m, TRUE);
216 if (vm_page_active(m))
217 vm_page_reference(m);
221 VM_OBJECT_WUNLOCK(obj);
222 error = uiomove_fromphys(&m, offset, tlen, uio);
223 if (uio->uio_rw == UIO_WRITE && error == 0) {
224 VM_OBJECT_WLOCK(obj);
226 vm_pager_page_unswapped(m);
227 VM_OBJECT_WUNLOCK(obj);
237 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
244 while ((resid = uio->uio_resid) > 0) {
245 if (obj_size <= uio->uio_offset)
247 len = MIN(obj_size - uio->uio_offset, resid);
250 error = uiomove_object_page(obj, len, uio);
251 if (error != 0 || resid == uio->uio_resid)
258 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
265 foffset = foffset_lock(fp, 0);
270 (offset > 0 && foffset > OFF_MAX - offset)) {
277 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
281 offset += shmfd->shm_size;
289 if (offset < 0 || offset > shmfd->shm_size)
292 td->td_uretoff.tdu_off = offset;
294 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
299 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
300 int flags, struct thread *td)
308 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
312 foffset_lock_uio(fp, uio, flags);
313 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
314 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
315 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
316 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
317 foffset_unlock_uio(fp, uio, flags);
322 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
323 int flags, struct thread *td)
331 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
335 foffset_lock_uio(fp, uio, flags);
336 if ((flags & FOF_OFFSET) == 0) {
337 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
340 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
341 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
344 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
345 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
346 foffset_unlock_uio(fp, uio, flags);
351 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
361 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
365 return (shm_dotruncate(shmfd, length));
369 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
377 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
378 * just like it would on an unlinked regular file
387 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
398 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
404 * Attempt to return sanish values for fstat() on a memory file
407 bzero(sb, sizeof(*sb));
408 sb->st_blksize = PAGE_SIZE;
409 sb->st_size = shmfd->shm_size;
410 sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
411 mtx_lock(&shm_timestamp_lock);
412 sb->st_atim = shmfd->shm_atime;
413 sb->st_ctim = shmfd->shm_ctime;
414 sb->st_mtim = shmfd->shm_mtime;
415 sb->st_birthtim = shmfd->shm_birthtime;
416 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
417 sb->st_uid = shmfd->shm_uid;
418 sb->st_gid = shmfd->shm_gid;
419 mtx_unlock(&shm_timestamp_lock);
420 sb->st_dev = shm_dev_ino;
421 sb->st_ino = shmfd->shm_ino;
427 shm_close(struct file *fp, struct thread *td)
439 shm_dotruncate(struct shmfd *shmfd, off_t length)
443 vm_pindex_t idx, nobjsize;
447 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
448 object = shmfd->shm_object;
449 VM_OBJECT_WLOCK(object);
450 if (length == shmfd->shm_size) {
451 VM_OBJECT_WUNLOCK(object);
454 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
456 /* Are we shrinking? If so, trim the end. */
457 if (length < shmfd->shm_size) {
459 * Disallow any requests to shrink the size if this
460 * object is mapped into the kernel.
462 if (shmfd->shm_kmappings > 0) {
463 VM_OBJECT_WUNLOCK(object);
468 * Zero the truncated part of the last page.
470 base = length & PAGE_MASK;
472 idx = OFF_TO_IDX(length);
474 m = vm_page_lookup(object, idx);
476 if (vm_page_sleep_if_busy(m, "shmtrc"))
478 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
479 m = vm_page_alloc(object, idx,
480 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
483 rv = vm_pager_get_pages(object, &m, 1, NULL,
486 if (rv == VM_PAGER_OK) {
488 * Since the page was not resident,
489 * and therefore not recently
490 * accessed, immediately enqueue it
491 * for asynchronous laundering. The
492 * current operation is not regarded
501 VM_OBJECT_WUNLOCK(object);
506 pmap_zero_page_area(m, base, PAGE_SIZE - base);
507 KASSERT(m->valid == VM_PAGE_BITS_ALL,
508 ("shm_dotruncate: page %p is invalid", m));
510 vm_pager_page_unswapped(m);
513 delta = IDX_TO_OFF(object->size - nobjsize);
515 /* Toss in memory pages. */
516 if (nobjsize < object->size)
517 vm_object_page_remove(object, nobjsize, object->size,
520 /* Toss pages from swap. */
521 if (object->type == OBJT_SWAP)
522 swap_pager_freespace(object, nobjsize, delta);
524 /* Free the swap accounted for shm */
525 swap_release_by_cred(delta, object->cred);
526 object->charge -= delta;
528 /* Try to reserve additional swap space. */
529 delta = IDX_TO_OFF(nobjsize - object->size);
530 if (!swap_reserve_by_cred(delta, object->cred)) {
531 VM_OBJECT_WUNLOCK(object);
534 object->charge += delta;
536 shmfd->shm_size = length;
537 mtx_lock(&shm_timestamp_lock);
538 vfs_timestamp(&shmfd->shm_ctime);
539 shmfd->shm_mtime = shmfd->shm_ctime;
540 mtx_unlock(&shm_timestamp_lock);
541 object->size = nobjsize;
542 VM_OBJECT_WUNLOCK(object);
547 * shmfd object management including creation and reference counting
551 shm_alloc(struct ucred *ucred, mode_t mode)
555 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
557 shmfd->shm_uid = ucred->cr_uid;
558 shmfd->shm_gid = ucred->cr_gid;
559 shmfd->shm_mode = mode;
560 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
561 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
562 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
563 shmfd->shm_object->pg_color = 0;
564 VM_OBJECT_WLOCK(shmfd->shm_object);
565 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
566 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT);
567 VM_OBJECT_WUNLOCK(shmfd->shm_object);
568 vfs_timestamp(&shmfd->shm_birthtime);
569 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
570 shmfd->shm_birthtime;
571 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
572 refcount_init(&shmfd->shm_refs, 1);
573 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
574 rangelock_init(&shmfd->shm_rl);
576 mac_posixshm_init(shmfd);
577 mac_posixshm_create(ucred, shmfd);
584 shm_hold(struct shmfd *shmfd)
587 refcount_acquire(&shmfd->shm_refs);
592 shm_drop(struct shmfd *shmfd)
595 if (refcount_release(&shmfd->shm_refs)) {
597 mac_posixshm_destroy(shmfd);
599 rangelock_destroy(&shmfd->shm_rl);
600 mtx_destroy(&shmfd->shm_mtx);
601 vm_object_deallocate(shmfd->shm_object);
602 free(shmfd, M_SHMFD);
607 * Determine if the credentials have sufficient permissions for a
608 * specified combination of FREAD and FWRITE.
611 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
621 mtx_lock(&shm_timestamp_lock);
622 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
623 accmode, ucred, NULL);
624 mtx_unlock(&shm_timestamp_lock);
629 * Dictionary management. We maintain an in-kernel dictionary to map
630 * paths to shmfd objects. We use the FNV hash on the path to store
631 * the mappings in a hash table.
637 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
638 sx_init(&shm_dict_lock, "shm dictionary");
639 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
640 new_unrhdr64(&shm_ino_unr, 1);
641 shm_dev_ino = devfs_alloc_cdp_inode();
642 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
644 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
646 static struct shmfd *
647 shm_lookup(char *path, Fnv32_t fnv)
649 struct shm_mapping *map;
651 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
652 if (map->sm_fnv != fnv)
654 if (strcmp(map->sm_path, path) == 0)
655 return (map->sm_shmfd);
662 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
664 struct shm_mapping *map;
666 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
669 map->sm_shmfd = shm_hold(shmfd);
670 shmfd->shm_path = path;
671 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
675 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
677 struct shm_mapping *map;
680 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
681 if (map->sm_fnv != fnv)
683 if (strcmp(map->sm_path, path) == 0) {
685 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
689 error = shm_access(map->sm_shmfd, ucred,
693 map->sm_shmfd->shm_path = NULL;
694 LIST_REMOVE(map, sm_link);
695 shm_drop(map->sm_shmfd);
696 free(map->sm_path, M_SHMFD);
706 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
707 struct filecaps *fcaps)
709 struct filedesc *fdp;
719 #ifdef CAPABILITY_MODE
721 * shm_open(2) is only allowed for anonymous objects.
723 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
727 AUDIT_ARG_FFLAGS(flags);
728 AUDIT_ARG_MODE(mode);
730 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
733 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
736 fdp = td->td_proc->p_fd;
737 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
739 error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps);
743 /* A SHM_ANON path pointer creates an anonymous object. */
744 if (userpath == SHM_ANON) {
745 /* A read-only anonymous object is pointless. */
746 if ((flags & O_ACCMODE) == O_RDONLY) {
751 shmfd = shm_alloc(td->td_ucred, cmode);
753 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
754 pr_path = td->td_ucred->cr_prison->pr_path;
756 /* Construct a full pathname for jailed callers. */
757 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
758 : strlcpy(path, pr_path, MAXPATHLEN);
759 error = copyinstr(userpath, path + pr_pathlen,
760 MAXPATHLEN - pr_pathlen, NULL);
762 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
765 /* Require paths to start with a '/' character. */
766 if (error == 0 && path[pr_pathlen] != '/')
775 AUDIT_ARG_UPATH1_CANON(path);
776 fnv = fnv_32_str(path, FNV1_32_INIT);
777 sx_xlock(&shm_dict_lock);
778 shmfd = shm_lookup(path, fnv);
780 /* Object does not yet exist, create it if requested. */
781 if (flags & O_CREAT) {
783 error = mac_posixshm_check_create(td->td_ucred,
787 shmfd = shm_alloc(td->td_ucred, cmode);
788 shm_insert(path, fnv, shmfd);
798 * Object already exists, obtain a new
799 * reference if requested and permitted.
802 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
806 error = mac_posixshm_check_open(td->td_ucred,
807 shmfd, FFLAGS(flags & O_ACCMODE));
810 error = shm_access(shmfd, td->td_ucred,
811 FFLAGS(flags & O_ACCMODE));
815 * Truncate the file back to zero length if
816 * O_TRUNC was specified and the object was
817 * opened with read/write.
820 (flags & (O_ACCMODE | O_TRUNC)) ==
821 (O_RDWR | O_TRUNC)) {
823 error = mac_posixshm_check_truncate(
824 td->td_ucred, fp->f_cred, shmfd);
827 shm_dotruncate(shmfd, 0);
832 sx_xunlock(&shm_dict_lock);
841 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
843 td->td_retval[0] = fd;
851 sys_shm_open(struct thread *td, struct shm_open_args *uap)
854 return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL));
858 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
866 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
867 pr_path = td->td_ucred->cr_prison->pr_path;
868 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
869 : strlcpy(path, pr_path, MAXPATHLEN);
870 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
877 if (KTRPOINT(curthread, KTR_NAMEI))
880 AUDIT_ARG_UPATH1_CANON(path);
881 fnv = fnv_32_str(path, FNV1_32_INIT);
882 sx_xlock(&shm_dict_lock);
883 error = shm_remove(path, fnv, td->td_ucred);
884 sx_xunlock(&shm_dict_lock);
891 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
892 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
893 vm_ooffset_t foff, struct thread *td)
900 maxprot = VM_PROT_NONE;
902 /* FREAD should always be set. */
903 if ((fp->f_flag & FREAD) != 0)
904 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
905 if ((fp->f_flag & FWRITE) != 0)
906 maxprot |= VM_PROT_WRITE;
908 /* Don't permit shared writable mappings on read-only descriptors. */
909 if ((flags & MAP_SHARED) != 0 &&
910 (maxprot & VM_PROT_WRITE) == 0 &&
911 (prot & VM_PROT_WRITE) != 0)
913 maxprot &= cap_maxprot;
915 /* See comment in vn_mmap(). */
920 foff < 0 || foff > OFF_MAX - objsize)
924 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
929 mtx_lock(&shm_timestamp_lock);
930 vfs_timestamp(&shmfd->shm_atime);
931 mtx_unlock(&shm_timestamp_lock);
932 vm_object_reference(shmfd->shm_object);
934 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
935 shmfd->shm_object, foff, FALSE, td);
937 vm_object_deallocate(shmfd->shm_object);
942 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
950 mtx_lock(&shm_timestamp_lock);
952 * SUSv4 says that x bits of permission need not be affected.
953 * Be consistent with our shm_open there.
956 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
960 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
961 shmfd->shm_gid, VADMIN, active_cred, NULL);
964 shmfd->shm_mode = mode & ACCESSPERMS;
966 mtx_unlock(&shm_timestamp_lock);
971 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
979 mtx_lock(&shm_timestamp_lock);
981 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
985 if (uid == (uid_t)-1)
986 uid = shmfd->shm_uid;
987 if (gid == (gid_t)-1)
988 gid = shmfd->shm_gid;
989 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
990 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
991 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
993 shmfd->shm_uid = uid;
994 shmfd->shm_gid = gid;
996 mtx_unlock(&shm_timestamp_lock);
1001 * Helper routines to allow the backing object of a shared memory file
1002 * descriptor to be mapped in the kernel.
1005 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1007 struct shmfd *shmfd;
1008 vm_offset_t kva, ofs;
1012 if (fp->f_type != DTYPE_SHM)
1015 obj = shmfd->shm_object;
1016 VM_OBJECT_WLOCK(obj);
1018 * XXXRW: This validation is probably insufficient, and subject to
1019 * sign errors. It should be fixed.
1021 if (offset >= shmfd->shm_size ||
1022 offset + size > round_page(shmfd->shm_size)) {
1023 VM_OBJECT_WUNLOCK(obj);
1027 shmfd->shm_kmappings++;
1028 vm_object_reference_locked(obj);
1029 VM_OBJECT_WUNLOCK(obj);
1031 /* Map the object into the kernel_map and wire it. */
1032 kva = vm_map_min(kernel_map);
1033 ofs = offset & PAGE_MASK;
1034 offset = trunc_page(offset);
1035 size = round_page(size + ofs);
1036 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1037 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1038 VM_PROT_READ | VM_PROT_WRITE, 0);
1039 if (rv == KERN_SUCCESS) {
1040 rv = vm_map_wire(kernel_map, kva, kva + size,
1041 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1042 if (rv == KERN_SUCCESS) {
1043 *memp = (void *)(kva + ofs);
1046 vm_map_remove(kernel_map, kva, kva + size);
1048 vm_object_deallocate(obj);
1050 /* On failure, drop our mapping reference. */
1051 VM_OBJECT_WLOCK(obj);
1052 shmfd->shm_kmappings--;
1053 VM_OBJECT_WUNLOCK(obj);
1055 return (vm_mmap_to_errno(rv));
1059 * We require the caller to unmap the entire entry. This allows us to
1060 * safely decrement shm_kmappings when a mapping is removed.
1063 shm_unmap(struct file *fp, void *mem, size_t size)
1065 struct shmfd *shmfd;
1066 vm_map_entry_t entry;
1067 vm_offset_t kva, ofs;
1075 if (fp->f_type != DTYPE_SHM)
1078 kva = (vm_offset_t)mem;
1079 ofs = kva & PAGE_MASK;
1080 kva = trunc_page(kva);
1081 size = round_page(size + ofs);
1083 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1084 &obj, &pindex, &prot, &wired);
1085 if (rv != KERN_SUCCESS)
1087 if (entry->start != kva || entry->end != kva + size) {
1088 vm_map_lookup_done(map, entry);
1091 vm_map_lookup_done(map, entry);
1092 if (obj != shmfd->shm_object)
1094 vm_map_remove(map, kva, kva + size);
1095 VM_OBJECT_WLOCK(obj);
1096 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1097 shmfd->shm_kmappings--;
1098 VM_OBJECT_WUNLOCK(obj);
1103 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1105 const char *path, *pr_path;
1106 struct shmfd *shmfd;
1109 kif->kf_type = KF_TYPE_SHM;
1112 mtx_lock(&shm_timestamp_lock);
1113 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; /* XXX */
1114 mtx_unlock(&shm_timestamp_lock);
1115 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1116 if (shmfd->shm_path != NULL) {
1117 sx_slock(&shm_dict_lock);
1118 if (shmfd->shm_path != NULL) {
1119 path = shmfd->shm_path;
1120 pr_path = curthread->td_ucred->cr_prison->pr_path;
1121 if (strcmp(pr_path, "/") != 0) {
1122 /* Return the jail-rooted pathname. */
1123 pr_pathlen = strlen(pr_path);
1124 if (strncmp(path, pr_path, pr_pathlen) == 0 &&
1125 path[pr_pathlen] == '/')
1128 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1130 sx_sunlock(&shm_dict_lock);