2 * Copyright (c) 2006, 2011 Robert N. M. Watson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
28 * Support for shared swap-backed anonymous memory objects via
29 * shm_open(2) and shm_unlink(2). While most of the implementation is
30 * here, vm_mmap.c contains mapping logic changes.
34 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1)
35 * and ipcrm(1) be expanded or should new tools to manage both POSIX
36 * kernel semaphores and POSIX shared memory be written?
38 * (2) Add support for this file type to fstat(1).
40 * (3) Resource limits? Does this need its own resource limits or are the
41 * existing limits in mmap(2) sufficient?
44 #include <sys/cdefs.h>
45 __FBSDID("$FreeBSD$");
47 #include "opt_capsicum.h"
48 #include "opt_ktrace.h"
50 #include <sys/param.h>
51 #include <sys/capsicum.h>
53 #include <sys/fcntl.h>
55 #include <sys/filedesc.h>
56 #include <sys/fnv_hash.h>
57 #include <sys/kernel.h>
59 #include <sys/signal.h>
61 #include <sys/ktrace.h>
63 #include <sys/malloc.h>
65 #include <sys/mutex.h>
68 #include <sys/refcount.h>
69 #include <sys/resourcevar.h>
70 #include <sys/rwlock.h>
72 #include <sys/syscallsubr.h>
73 #include <sys/sysctl.h>
74 #include <sys/sysproto.h>
75 #include <sys/systm.h>
78 #include <sys/vnode.h>
79 #include <sys/unistd.h>
82 #include <security/mac/mac_framework.h>
85 #include <vm/vm_param.h>
87 #include <vm/vm_extern.h>
88 #include <vm/vm_map.h>
89 #include <vm/vm_kern.h>
90 #include <vm/vm_object.h>
91 #include <vm/vm_page.h>
92 #include <vm/vm_pageout.h>
93 #include <vm/vm_pager.h>
94 #include <vm/swap_pager.h>
99 struct shmfd *sm_shmfd;
100 LIST_ENTRY(shm_mapping) sm_link;
103 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
104 static LIST_HEAD(, shm_mapping) *shm_dictionary;
105 static struct sx shm_dict_lock;
106 static struct mtx shm_timestamp_lock;
107 static u_long shm_hash;
108 static struct unrhdr *shm_ino_unr;
109 static dev_t shm_dev_ino;
111 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
113 static void shm_init(void *arg);
114 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
115 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
116 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
118 static fo_rdwr_t shm_read;
119 static fo_rdwr_t shm_write;
120 static fo_truncate_t shm_truncate;
121 static fo_stat_t shm_stat;
122 static fo_close_t shm_close;
123 static fo_chmod_t shm_chmod;
124 static fo_chown_t shm_chown;
125 static fo_seek_t shm_seek;
126 static fo_fill_kinfo_t shm_fill_kinfo;
127 static fo_mmap_t shm_mmap;
129 /* File descriptor operations. */
130 struct fileops shm_ops = {
132 .fo_write = shm_write,
133 .fo_truncate = shm_truncate,
134 .fo_ioctl = invfo_ioctl,
135 .fo_poll = invfo_poll,
136 .fo_kqfilter = invfo_kqfilter,
138 .fo_close = shm_close,
139 .fo_chmod = shm_chmod,
140 .fo_chown = shm_chown,
141 .fo_sendfile = vn_sendfile,
143 .fo_fill_kinfo = shm_fill_kinfo,
145 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
148 FEATURE(posix_shm, "POSIX shared memory");
151 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
156 int error, offset, rv;
158 idx = OFF_TO_IDX(uio->uio_offset);
159 offset = uio->uio_offset & PAGE_MASK;
160 tlen = MIN(PAGE_SIZE - offset, len);
162 VM_OBJECT_WLOCK(obj);
165 * Read I/O without either a corresponding resident page or swap
166 * page: use zero_region. This is intended to avoid instantiating
167 * pages on read from a sparse region.
169 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL &&
170 !vm_pager_has_page(obj, idx, NULL, NULL)) {
171 VM_OBJECT_WUNLOCK(obj);
172 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
176 * Parallel reads of the page content from disk are prevented
179 * Although the tmpfs vnode lock is held here, it is
180 * nonetheless safe to sleep waiting for a free page. The
181 * pageout daemon does not need to acquire the tmpfs vnode
182 * lock to page out tobj's pages because tobj is a OBJT_SWAP
185 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
186 if (m->valid != VM_PAGE_BITS_ALL) {
188 if (vm_pager_has_page(obj, idx, NULL, NULL)) {
189 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
190 if (rv != VM_PAGER_OK) {
192 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
193 obj, idx, m->valid, rv);
197 VM_OBJECT_WUNLOCK(obj);
201 vm_page_zero_invalid(m, TRUE);
206 if (m->queue != PQ_ACTIVE)
209 vm_page_reference(m);
211 VM_OBJECT_WUNLOCK(obj);
212 error = uiomove_fromphys(&m, offset, tlen, uio);
213 if (uio->uio_rw == UIO_WRITE && error == 0) {
214 VM_OBJECT_WLOCK(obj);
216 vm_pager_page_unswapped(m);
217 VM_OBJECT_WUNLOCK(obj);
227 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
234 while ((resid = uio->uio_resid) > 0) {
235 if (obj_size <= uio->uio_offset)
237 len = MIN(obj_size - uio->uio_offset, resid);
240 error = uiomove_object_page(obj, len, uio);
241 if (error != 0 || resid == uio->uio_resid)
248 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
255 foffset = foffset_lock(fp, 0);
260 (offset > 0 && foffset > OFF_MAX - offset)) {
267 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
271 offset += shmfd->shm_size;
279 if (offset < 0 || offset > shmfd->shm_size)
282 td->td_uretoff.tdu_off = offset;
284 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
289 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
290 int flags, struct thread *td)
298 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
302 foffset_lock_uio(fp, uio, flags);
303 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
304 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
305 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
306 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
307 foffset_unlock_uio(fp, uio, flags);
312 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
313 int flags, struct thread *td)
321 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
325 foffset_lock_uio(fp, uio, flags);
326 if ((flags & FOF_OFFSET) == 0) {
327 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
330 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
331 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
334 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
335 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
336 foffset_unlock_uio(fp, uio, flags);
341 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
351 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
355 return (shm_dotruncate(shmfd, length));
359 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
370 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
376 * Attempt to return sanish values for fstat() on a memory file
379 bzero(sb, sizeof(*sb));
380 sb->st_blksize = PAGE_SIZE;
381 sb->st_size = shmfd->shm_size;
382 sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
383 mtx_lock(&shm_timestamp_lock);
384 sb->st_atim = shmfd->shm_atime;
385 sb->st_ctim = shmfd->shm_ctime;
386 sb->st_mtim = shmfd->shm_mtime;
387 sb->st_birthtim = shmfd->shm_birthtime;
388 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
389 sb->st_uid = shmfd->shm_uid;
390 sb->st_gid = shmfd->shm_gid;
391 mtx_unlock(&shm_timestamp_lock);
392 sb->st_dev = shm_dev_ino;
393 sb->st_ino = shmfd->shm_ino;
399 shm_close(struct file *fp, struct thread *td)
411 shm_dotruncate(struct shmfd *shmfd, off_t length)
415 vm_pindex_t idx, nobjsize;
419 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
420 object = shmfd->shm_object;
421 VM_OBJECT_WLOCK(object);
422 if (length == shmfd->shm_size) {
423 VM_OBJECT_WUNLOCK(object);
426 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
428 /* Are we shrinking? If so, trim the end. */
429 if (length < shmfd->shm_size) {
431 * Disallow any requests to shrink the size if this
432 * object is mapped into the kernel.
434 if (shmfd->shm_kmappings > 0) {
435 VM_OBJECT_WUNLOCK(object);
440 * Zero the truncated part of the last page.
442 base = length & PAGE_MASK;
444 idx = OFF_TO_IDX(length);
446 m = vm_page_lookup(object, idx);
448 if (vm_page_sleep_if_busy(m, "shmtrc"))
450 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
451 m = vm_page_alloc(object, idx,
452 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
455 rv = vm_pager_get_pages(object, &m, 1, NULL,
458 if (rv == VM_PAGER_OK) {
459 vm_page_deactivate(m);
465 VM_OBJECT_WUNLOCK(object);
470 pmap_zero_page_area(m, base, PAGE_SIZE - base);
471 KASSERT(m->valid == VM_PAGE_BITS_ALL,
472 ("shm_dotruncate: page %p is invalid", m));
474 vm_pager_page_unswapped(m);
477 delta = IDX_TO_OFF(object->size - nobjsize);
479 /* Toss in memory pages. */
480 if (nobjsize < object->size)
481 vm_object_page_remove(object, nobjsize, object->size,
484 /* Toss pages from swap. */
485 if (object->type == OBJT_SWAP)
486 swap_pager_freespace(object, nobjsize, delta);
488 /* Free the swap accounted for shm */
489 swap_release_by_cred(delta, object->cred);
490 object->charge -= delta;
492 /* Try to reserve additional swap space. */
493 delta = IDX_TO_OFF(nobjsize - object->size);
494 if (!swap_reserve_by_cred(delta, object->cred)) {
495 VM_OBJECT_WUNLOCK(object);
498 object->charge += delta;
500 shmfd->shm_size = length;
501 mtx_lock(&shm_timestamp_lock);
502 vfs_timestamp(&shmfd->shm_ctime);
503 shmfd->shm_mtime = shmfd->shm_ctime;
504 mtx_unlock(&shm_timestamp_lock);
505 object->size = nobjsize;
506 VM_OBJECT_WUNLOCK(object);
511 * shmfd object management including creation and reference counting
515 shm_alloc(struct ucred *ucred, mode_t mode)
520 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
522 shmfd->shm_uid = ucred->cr_uid;
523 shmfd->shm_gid = ucred->cr_gid;
524 shmfd->shm_mode = mode;
525 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
526 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
527 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
528 shmfd->shm_object->pg_color = 0;
529 VM_OBJECT_WLOCK(shmfd->shm_object);
530 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
531 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT);
532 VM_OBJECT_WUNLOCK(shmfd->shm_object);
533 vfs_timestamp(&shmfd->shm_birthtime);
534 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
535 shmfd->shm_birthtime;
536 ino = alloc_unr(shm_ino_unr);
540 shmfd->shm_ino = ino;
541 refcount_init(&shmfd->shm_refs, 1);
542 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
543 rangelock_init(&shmfd->shm_rl);
545 mac_posixshm_init(shmfd);
546 mac_posixshm_create(ucred, shmfd);
553 shm_hold(struct shmfd *shmfd)
556 refcount_acquire(&shmfd->shm_refs);
561 shm_drop(struct shmfd *shmfd)
564 if (refcount_release(&shmfd->shm_refs)) {
566 mac_posixshm_destroy(shmfd);
568 rangelock_destroy(&shmfd->shm_rl);
569 mtx_destroy(&shmfd->shm_mtx);
570 vm_object_deallocate(shmfd->shm_object);
571 if (shmfd->shm_ino != 0)
572 free_unr(shm_ino_unr, shmfd->shm_ino);
573 free(shmfd, M_SHMFD);
578 * Determine if the credentials have sufficient permissions for a
579 * specified combination of FREAD and FWRITE.
582 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
592 mtx_lock(&shm_timestamp_lock);
593 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
594 accmode, ucred, NULL);
595 mtx_unlock(&shm_timestamp_lock);
600 * Dictionary management. We maintain an in-kernel dictionary to map
601 * paths to shmfd objects. We use the FNV hash on the path to store
602 * the mappings in a hash table.
608 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
609 sx_init(&shm_dict_lock, "shm dictionary");
610 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
611 shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL);
612 KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized"));
613 shm_dev_ino = devfs_alloc_cdp_inode();
614 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
616 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
618 static struct shmfd *
619 shm_lookup(char *path, Fnv32_t fnv)
621 struct shm_mapping *map;
623 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
624 if (map->sm_fnv != fnv)
626 if (strcmp(map->sm_path, path) == 0)
627 return (map->sm_shmfd);
634 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
636 struct shm_mapping *map;
638 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
641 map->sm_shmfd = shm_hold(shmfd);
642 shmfd->shm_path = path;
643 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
647 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
649 struct shm_mapping *map;
652 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
653 if (map->sm_fnv != fnv)
655 if (strcmp(map->sm_path, path) == 0) {
657 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
661 error = shm_access(map->sm_shmfd, ucred,
665 map->sm_shmfd->shm_path = NULL;
666 LIST_REMOVE(map, sm_link);
667 shm_drop(map->sm_shmfd);
668 free(map->sm_path, M_SHMFD);
678 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
679 struct filecaps *fcaps)
681 struct filedesc *fdp;
691 #ifdef CAPABILITY_MODE
693 * shm_open(2) is only allowed for anonymous objects.
695 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
699 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
702 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
705 fdp = td->td_proc->p_fd;
706 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
708 error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps);
712 /* A SHM_ANON path pointer creates an anonymous object. */
713 if (userpath == SHM_ANON) {
714 /* A read-only anonymous object is pointless. */
715 if ((flags & O_ACCMODE) == O_RDONLY) {
720 shmfd = shm_alloc(td->td_ucred, cmode);
722 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
723 pr_path = td->td_ucred->cr_prison->pr_path;
725 /* Construct a full pathname for jailed callers. */
726 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
727 : strlcpy(path, pr_path, MAXPATHLEN);
728 error = copyinstr(userpath, path + pr_pathlen,
729 MAXPATHLEN - pr_pathlen, NULL);
731 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
734 /* Require paths to start with a '/' character. */
735 if (error == 0 && path[pr_pathlen] != '/')
744 fnv = fnv_32_str(path, FNV1_32_INIT);
745 sx_xlock(&shm_dict_lock);
746 shmfd = shm_lookup(path, fnv);
748 /* Object does not yet exist, create it if requested. */
749 if (flags & O_CREAT) {
751 error = mac_posixshm_check_create(td->td_ucred,
755 shmfd = shm_alloc(td->td_ucred, cmode);
756 shm_insert(path, fnv, shmfd);
766 * Object already exists, obtain a new
767 * reference if requested and permitted.
770 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
774 error = mac_posixshm_check_open(td->td_ucred,
775 shmfd, FFLAGS(flags & O_ACCMODE));
778 error = shm_access(shmfd, td->td_ucred,
779 FFLAGS(flags & O_ACCMODE));
783 * Truncate the file back to zero length if
784 * O_TRUNC was specified and the object was
785 * opened with read/write.
788 (flags & (O_ACCMODE | O_TRUNC)) ==
789 (O_RDWR | O_TRUNC)) {
791 error = mac_posixshm_check_truncate(
792 td->td_ucred, fp->f_cred, shmfd);
795 shm_dotruncate(shmfd, 0);
800 sx_xunlock(&shm_dict_lock);
809 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
811 td->td_retval[0] = fd;
819 sys_shm_open(struct thread *td, struct shm_open_args *uap)
822 return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL));
826 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
834 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
835 pr_path = td->td_ucred->cr_prison->pr_path;
836 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
837 : strlcpy(path, pr_path, MAXPATHLEN);
838 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
845 if (KTRPOINT(curthread, KTR_NAMEI))
848 fnv = fnv_32_str(path, FNV1_32_INIT);
849 sx_xlock(&shm_dict_lock);
850 error = shm_remove(path, fnv, td->td_ucred);
851 sx_xunlock(&shm_dict_lock);
858 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
859 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
860 vm_ooffset_t foff, struct thread *td)
867 maxprot = VM_PROT_NONE;
869 /* FREAD should always be set. */
870 if ((fp->f_flag & FREAD) != 0)
871 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
872 if ((fp->f_flag & FWRITE) != 0)
873 maxprot |= VM_PROT_WRITE;
875 /* Don't permit shared writable mappings on read-only descriptors. */
876 if ((flags & MAP_SHARED) != 0 &&
877 (maxprot & VM_PROT_WRITE) == 0 &&
878 (prot & VM_PROT_WRITE) != 0)
880 maxprot &= cap_maxprot;
882 /* See comment in vn_mmap(). */
887 foff < 0 || foff > OFF_MAX - objsize)
891 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
896 mtx_lock(&shm_timestamp_lock);
897 vfs_timestamp(&shmfd->shm_atime);
898 mtx_unlock(&shm_timestamp_lock);
899 vm_object_reference(shmfd->shm_object);
901 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
902 shmfd->shm_object, foff, FALSE, td);
904 vm_object_deallocate(shmfd->shm_object);
909 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
917 mtx_lock(&shm_timestamp_lock);
919 * SUSv4 says that x bits of permission need not be affected.
920 * Be consistent with our shm_open there.
923 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
927 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
928 shmfd->shm_gid, VADMIN, active_cred, NULL);
931 shmfd->shm_mode = mode & ACCESSPERMS;
933 mtx_unlock(&shm_timestamp_lock);
938 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
946 mtx_lock(&shm_timestamp_lock);
948 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
952 if (uid == (uid_t)-1)
953 uid = shmfd->shm_uid;
954 if (gid == (gid_t)-1)
955 gid = shmfd->shm_gid;
956 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
957 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
958 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
960 shmfd->shm_uid = uid;
961 shmfd->shm_gid = gid;
963 mtx_unlock(&shm_timestamp_lock);
968 * Helper routines to allow the backing object of a shared memory file
969 * descriptor to be mapped in the kernel.
972 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
975 vm_offset_t kva, ofs;
979 if (fp->f_type != DTYPE_SHM)
982 obj = shmfd->shm_object;
983 VM_OBJECT_WLOCK(obj);
985 * XXXRW: This validation is probably insufficient, and subject to
986 * sign errors. It should be fixed.
988 if (offset >= shmfd->shm_size ||
989 offset + size > round_page(shmfd->shm_size)) {
990 VM_OBJECT_WUNLOCK(obj);
994 shmfd->shm_kmappings++;
995 vm_object_reference_locked(obj);
996 VM_OBJECT_WUNLOCK(obj);
998 /* Map the object into the kernel_map and wire it. */
999 kva = vm_map_min(kernel_map);
1000 ofs = offset & PAGE_MASK;
1001 offset = trunc_page(offset);
1002 size = round_page(size + ofs);
1003 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1004 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1005 VM_PROT_READ | VM_PROT_WRITE, 0);
1006 if (rv == KERN_SUCCESS) {
1007 rv = vm_map_wire(kernel_map, kva, kva + size,
1008 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1009 if (rv == KERN_SUCCESS) {
1010 *memp = (void *)(kva + ofs);
1013 vm_map_remove(kernel_map, kva, kva + size);
1015 vm_object_deallocate(obj);
1017 /* On failure, drop our mapping reference. */
1018 VM_OBJECT_WLOCK(obj);
1019 shmfd->shm_kmappings--;
1020 VM_OBJECT_WUNLOCK(obj);
1022 return (vm_mmap_to_errno(rv));
1026 * We require the caller to unmap the entire entry. This allows us to
1027 * safely decrement shm_kmappings when a mapping is removed.
1030 shm_unmap(struct file *fp, void *mem, size_t size)
1032 struct shmfd *shmfd;
1033 vm_map_entry_t entry;
1034 vm_offset_t kva, ofs;
1042 if (fp->f_type != DTYPE_SHM)
1045 kva = (vm_offset_t)mem;
1046 ofs = kva & PAGE_MASK;
1047 kva = trunc_page(kva);
1048 size = round_page(size + ofs);
1050 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1051 &obj, &pindex, &prot, &wired);
1052 if (rv != KERN_SUCCESS)
1054 if (entry->start != kva || entry->end != kva + size) {
1055 vm_map_lookup_done(map, entry);
1058 vm_map_lookup_done(map, entry);
1059 if (obj != shmfd->shm_object)
1061 vm_map_remove(map, kva, kva + size);
1062 VM_OBJECT_WLOCK(obj);
1063 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1064 shmfd->shm_kmappings--;
1065 VM_OBJECT_WUNLOCK(obj);
1070 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp)
1072 const char *path, *pr_path;
1073 struct shmfd *shmfd;
1076 kif->kf_type = KF_TYPE_SHM;
1079 mtx_lock(&shm_timestamp_lock);
1080 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; /* XXX */
1081 mtx_unlock(&shm_timestamp_lock);
1082 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1083 if (shmfd->shm_path != NULL) {
1084 sx_slock(&shm_dict_lock);
1085 if (shmfd->shm_path != NULL) {
1086 path = shmfd->shm_path;
1087 pr_path = curthread->td_ucred->cr_prison->pr_path;
1088 if (strcmp(pr_path, "/") != 0) {
1089 /* Return the jail-rooted pathname. */
1090 pr_pathlen = strlen(pr_path);
1091 if (strncmp(path, pr_path, pr_pathlen) == 0 &&
1092 path[pr_pathlen] == '/')
1095 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1097 sx_sunlock(&shm_dict_lock);