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.
39 * posixshmcontrol(1) allows users to inspect the state of the memory
40 * objects. Per-uid swap resource limit controls total amount of
41 * memory that user can consume for anonymous objects, including
45 #include <sys/cdefs.h>
46 __FBSDID("$FreeBSD$");
48 #include "opt_capsicum.h"
49 #include "opt_ktrace.h"
51 #include <sys/param.h>
52 #include <sys/capsicum.h>
54 #include <sys/fcntl.h>
56 #include <sys/filedesc.h>
57 #include <sys/filio.h>
58 #include <sys/fnv_hash.h>
59 #include <sys/kernel.h>
60 #include <sys/limits.h>
62 #include <sys/signal.h>
64 #include <sys/ktrace.h>
66 #include <sys/malloc.h>
68 #include <sys/mutex.h>
71 #include <sys/refcount.h>
72 #include <sys/resourcevar.h>
73 #include <sys/rwlock.h>
76 #include <sys/syscallsubr.h>
77 #include <sys/sysctl.h>
78 #include <sys/sysproto.h>
79 #include <sys/systm.h>
82 #include <sys/vnode.h>
83 #include <sys/unistd.h>
86 #include <security/audit/audit.h>
87 #include <security/mac/mac_framework.h>
90 #include <vm/vm_param.h>
92 #include <vm/vm_extern.h>
93 #include <vm/vm_map.h>
94 #include <vm/vm_kern.h>
95 #include <vm/vm_object.h>
96 #include <vm/vm_page.h>
97 #include <vm/vm_pageout.h>
98 #include <vm/vm_pager.h>
99 #include <vm/swap_pager.h>
104 struct shmfd *sm_shmfd;
105 LIST_ENTRY(shm_mapping) sm_link;
108 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
109 static LIST_HEAD(, shm_mapping) *shm_dictionary;
110 static struct sx shm_dict_lock;
111 static struct mtx shm_timestamp_lock;
112 static u_long shm_hash;
113 static struct unrhdr64 shm_ino_unr;
114 static dev_t shm_dev_ino;
116 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
118 static void shm_init(void *arg);
119 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
120 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
121 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
123 static fo_rdwr_t shm_read;
124 static fo_rdwr_t shm_write;
125 static fo_truncate_t shm_truncate;
126 static fo_ioctl_t shm_ioctl;
127 static fo_stat_t shm_stat;
128 static fo_close_t shm_close;
129 static fo_chmod_t shm_chmod;
130 static fo_chown_t shm_chown;
131 static fo_seek_t shm_seek;
132 static fo_fill_kinfo_t shm_fill_kinfo;
133 static fo_mmap_t shm_mmap;
135 /* File descriptor operations. */
136 struct fileops shm_ops = {
138 .fo_write = shm_write,
139 .fo_truncate = shm_truncate,
140 .fo_ioctl = shm_ioctl,
141 .fo_poll = invfo_poll,
142 .fo_kqfilter = invfo_kqfilter,
144 .fo_close = shm_close,
145 .fo_chmod = shm_chmod,
146 .fo_chown = shm_chown,
147 .fo_sendfile = vn_sendfile,
149 .fo_fill_kinfo = shm_fill_kinfo,
151 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
154 FEATURE(posix_shm, "POSIX shared memory");
157 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
162 int error, offset, rv;
164 idx = OFF_TO_IDX(uio->uio_offset);
165 offset = uio->uio_offset & PAGE_MASK;
166 tlen = MIN(PAGE_SIZE - offset, len);
168 VM_OBJECT_WLOCK(obj);
171 * Read I/O without either a corresponding resident page or swap
172 * page: use zero_region. This is intended to avoid instantiating
173 * pages on read from a sparse region.
175 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL &&
176 !vm_pager_has_page(obj, idx, NULL, NULL)) {
177 VM_OBJECT_WUNLOCK(obj);
178 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
182 * Parallel reads of the page content from disk are prevented
185 * Although the tmpfs vnode lock is held here, it is
186 * nonetheless safe to sleep waiting for a free page. The
187 * pageout daemon does not need to acquire the tmpfs vnode
188 * lock to page out tobj's pages because tobj is a OBJT_SWAP
191 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
192 if (m->valid != VM_PAGE_BITS_ALL) {
194 if (vm_pager_has_page(obj, idx, NULL, NULL)) {
195 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
196 if (rv != VM_PAGER_OK) {
198 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
199 obj, idx, m->valid, rv);
203 VM_OBJECT_WUNLOCK(obj);
207 vm_page_zero_invalid(m, TRUE);
212 if (vm_page_active(m))
213 vm_page_reference(m);
217 VM_OBJECT_WUNLOCK(obj);
218 error = uiomove_fromphys(&m, offset, tlen, uio);
219 if (uio->uio_rw == UIO_WRITE && error == 0) {
220 VM_OBJECT_WLOCK(obj);
222 vm_pager_page_unswapped(m);
223 VM_OBJECT_WUNLOCK(obj);
233 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
240 while ((resid = uio->uio_resid) > 0) {
241 if (obj_size <= uio->uio_offset)
243 len = MIN(obj_size - uio->uio_offset, resid);
246 error = uiomove_object_page(obj, len, uio);
247 if (error != 0 || resid == uio->uio_resid)
254 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
261 foffset = foffset_lock(fp, 0);
266 (offset > 0 && foffset > OFF_MAX - offset)) {
273 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
277 offset += shmfd->shm_size;
285 if (offset < 0 || offset > shmfd->shm_size)
288 td->td_uretoff.tdu_off = offset;
290 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
295 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
296 int flags, struct thread *td)
304 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
308 foffset_lock_uio(fp, uio, flags);
309 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
310 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
311 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
312 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
313 foffset_unlock_uio(fp, uio, flags);
318 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
319 int flags, struct thread *td)
327 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
331 foffset_lock_uio(fp, uio, flags);
332 if ((flags & FOF_OFFSET) == 0) {
333 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
336 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
337 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
340 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
341 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
342 foffset_unlock_uio(fp, uio, flags);
347 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
357 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
361 return (shm_dotruncate(shmfd, length));
365 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
373 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
374 * just like it would on an unlinked regular file
383 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
394 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
400 * Attempt to return sanish values for fstat() on a memory file
403 bzero(sb, sizeof(*sb));
404 sb->st_blksize = PAGE_SIZE;
405 sb->st_size = shmfd->shm_size;
406 sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
407 mtx_lock(&shm_timestamp_lock);
408 sb->st_atim = shmfd->shm_atime;
409 sb->st_ctim = shmfd->shm_ctime;
410 sb->st_mtim = shmfd->shm_mtime;
411 sb->st_birthtim = shmfd->shm_birthtime;
412 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
413 sb->st_uid = shmfd->shm_uid;
414 sb->st_gid = shmfd->shm_gid;
415 mtx_unlock(&shm_timestamp_lock);
416 sb->st_dev = shm_dev_ino;
417 sb->st_ino = shmfd->shm_ino;
418 sb->st_nlink = shmfd->shm_object->ref_count;
424 shm_close(struct file *fp, struct thread *td)
436 shm_dotruncate(struct shmfd *shmfd, off_t length)
440 vm_pindex_t idx, nobjsize;
444 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
445 object = shmfd->shm_object;
446 VM_OBJECT_WLOCK(object);
447 if (length == shmfd->shm_size) {
448 VM_OBJECT_WUNLOCK(object);
451 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
453 /* Are we shrinking? If so, trim the end. */
454 if (length < shmfd->shm_size) {
456 * Disallow any requests to shrink the size if this
457 * object is mapped into the kernel.
459 if (shmfd->shm_kmappings > 0) {
460 VM_OBJECT_WUNLOCK(object);
465 * Zero the truncated part of the last page.
467 base = length & PAGE_MASK;
469 idx = OFF_TO_IDX(length);
471 m = vm_page_lookup(object, idx);
473 if (vm_page_sleep_if_busy(m, "shmtrc"))
475 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
476 m = vm_page_alloc(object, idx,
477 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
480 rv = vm_pager_get_pages(object, &m, 1, NULL,
483 if (rv == VM_PAGER_OK) {
485 * Since the page was not resident,
486 * and therefore not recently
487 * accessed, immediately enqueue it
488 * for asynchronous laundering. The
489 * current operation is not regarded
498 VM_OBJECT_WUNLOCK(object);
503 pmap_zero_page_area(m, base, PAGE_SIZE - base);
504 KASSERT(m->valid == VM_PAGE_BITS_ALL,
505 ("shm_dotruncate: page %p is invalid", m));
507 vm_pager_page_unswapped(m);
510 delta = IDX_TO_OFF(object->size - nobjsize);
512 /* Toss in memory pages. */
513 if (nobjsize < object->size)
514 vm_object_page_remove(object, nobjsize, object->size,
517 /* Toss pages from swap. */
518 if (object->type == OBJT_SWAP)
519 swap_pager_freespace(object, nobjsize, delta);
521 /* Free the swap accounted for shm */
522 swap_release_by_cred(delta, object->cred);
523 object->charge -= delta;
525 /* Try to reserve additional swap space. */
526 delta = IDX_TO_OFF(nobjsize - object->size);
527 if (!swap_reserve_by_cred(delta, object->cred)) {
528 VM_OBJECT_WUNLOCK(object);
531 object->charge += delta;
533 shmfd->shm_size = length;
534 mtx_lock(&shm_timestamp_lock);
535 vfs_timestamp(&shmfd->shm_ctime);
536 shmfd->shm_mtime = shmfd->shm_ctime;
537 mtx_unlock(&shm_timestamp_lock);
538 object->size = nobjsize;
539 VM_OBJECT_WUNLOCK(object);
544 * shmfd object management including creation and reference counting
548 shm_alloc(struct ucred *ucred, mode_t mode)
552 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
554 shmfd->shm_uid = ucred->cr_uid;
555 shmfd->shm_gid = ucred->cr_gid;
556 shmfd->shm_mode = mode;
557 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL,
558 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
559 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
560 shmfd->shm_object->pg_color = 0;
561 VM_OBJECT_WLOCK(shmfd->shm_object);
562 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
563 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT);
564 VM_OBJECT_WUNLOCK(shmfd->shm_object);
565 vfs_timestamp(&shmfd->shm_birthtime);
566 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
567 shmfd->shm_birthtime;
568 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
569 refcount_init(&shmfd->shm_refs, 1);
570 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
571 rangelock_init(&shmfd->shm_rl);
573 mac_posixshm_init(shmfd);
574 mac_posixshm_create(ucred, shmfd);
581 shm_hold(struct shmfd *shmfd)
584 refcount_acquire(&shmfd->shm_refs);
589 shm_drop(struct shmfd *shmfd)
592 if (refcount_release(&shmfd->shm_refs)) {
594 mac_posixshm_destroy(shmfd);
596 rangelock_destroy(&shmfd->shm_rl);
597 mtx_destroy(&shmfd->shm_mtx);
598 vm_object_deallocate(shmfd->shm_object);
599 free(shmfd, M_SHMFD);
604 * Determine if the credentials have sufficient permissions for a
605 * specified combination of FREAD and FWRITE.
608 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
618 mtx_lock(&shm_timestamp_lock);
619 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
620 accmode, ucred, NULL);
621 mtx_unlock(&shm_timestamp_lock);
626 * Dictionary management. We maintain an in-kernel dictionary to map
627 * paths to shmfd objects. We use the FNV hash on the path to store
628 * the mappings in a hash table.
634 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
635 sx_init(&shm_dict_lock, "shm dictionary");
636 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
637 new_unrhdr64(&shm_ino_unr, 1);
638 shm_dev_ino = devfs_alloc_cdp_inode();
639 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
641 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
643 static struct shmfd *
644 shm_lookup(char *path, Fnv32_t fnv)
646 struct shm_mapping *map;
648 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
649 if (map->sm_fnv != fnv)
651 if (strcmp(map->sm_path, path) == 0)
652 return (map->sm_shmfd);
659 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
661 struct shm_mapping *map;
663 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
666 map->sm_shmfd = shm_hold(shmfd);
667 shmfd->shm_path = path;
668 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
672 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
674 struct shm_mapping *map;
677 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
678 if (map->sm_fnv != fnv)
680 if (strcmp(map->sm_path, path) == 0) {
682 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
686 error = shm_access(map->sm_shmfd, ucred,
690 map->sm_shmfd->shm_path = NULL;
691 LIST_REMOVE(map, sm_link);
692 shm_drop(map->sm_shmfd);
693 free(map->sm_path, M_SHMFD);
703 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
704 struct filecaps *fcaps)
706 struct filedesc *fdp;
716 #ifdef CAPABILITY_MODE
718 * shm_open(2) is only allowed for anonymous objects.
720 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
724 AUDIT_ARG_FFLAGS(flags);
725 AUDIT_ARG_MODE(mode);
727 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
730 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
733 fdp = td->td_proc->p_fd;
734 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
737 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
738 * by POSIX. We allow it to be unset here so that an in-kernel
739 * interface may be written as a thin layer around shm, optionally not
740 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
741 * in sys_shm_open() to keep this implementation compliant.
743 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
747 /* A SHM_ANON path pointer creates an anonymous object. */
748 if (userpath == SHM_ANON) {
749 /* A read-only anonymous object is pointless. */
750 if ((flags & O_ACCMODE) == O_RDONLY) {
755 shmfd = shm_alloc(td->td_ucred, cmode);
757 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
758 pr_path = td->td_ucred->cr_prison->pr_path;
760 /* Construct a full pathname for jailed callers. */
761 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
762 : strlcpy(path, pr_path, MAXPATHLEN);
763 error = copyinstr(userpath, path + pr_pathlen,
764 MAXPATHLEN - pr_pathlen, NULL);
766 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
769 /* Require paths to start with a '/' character. */
770 if (error == 0 && path[pr_pathlen] != '/')
779 AUDIT_ARG_UPATH1_CANON(path);
780 fnv = fnv_32_str(path, FNV1_32_INIT);
781 sx_xlock(&shm_dict_lock);
782 shmfd = shm_lookup(path, fnv);
784 /* Object does not yet exist, create it if requested. */
785 if (flags & O_CREAT) {
787 error = mac_posixshm_check_create(td->td_ucred,
791 shmfd = shm_alloc(td->td_ucred, cmode);
792 shm_insert(path, fnv, shmfd);
802 * Object already exists, obtain a new
803 * reference if requested and permitted.
806 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
810 error = mac_posixshm_check_open(td->td_ucred,
811 shmfd, FFLAGS(flags & O_ACCMODE));
814 error = shm_access(shmfd, td->td_ucred,
815 FFLAGS(flags & O_ACCMODE));
819 * Truncate the file back to zero length if
820 * O_TRUNC was specified and the object was
821 * opened with read/write.
824 (flags & (O_ACCMODE | O_TRUNC)) ==
825 (O_RDWR | O_TRUNC)) {
827 error = mac_posixshm_check_truncate(
828 td->td_ucred, fp->f_cred, shmfd);
831 shm_dotruncate(shmfd, 0);
836 sx_xunlock(&shm_dict_lock);
845 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
847 td->td_retval[0] = fd;
855 sys_shm_open(struct thread *td, struct shm_open_args *uap)
858 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode,
863 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
871 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
872 pr_path = td->td_ucred->cr_prison->pr_path;
873 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
874 : strlcpy(path, pr_path, MAXPATHLEN);
875 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
882 if (KTRPOINT(curthread, KTR_NAMEI))
885 AUDIT_ARG_UPATH1_CANON(path);
886 fnv = fnv_32_str(path, FNV1_32_INIT);
887 sx_xlock(&shm_dict_lock);
888 error = shm_remove(path, fnv, td->td_ucred);
889 sx_xunlock(&shm_dict_lock);
896 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
897 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
898 vm_ooffset_t foff, struct thread *td)
906 maxprot = VM_PROT_NONE;
908 /* FREAD should always be set. */
909 if ((fp->f_flag & FREAD) != 0)
910 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
911 if ((fp->f_flag & FWRITE) != 0)
912 maxprot |= VM_PROT_WRITE;
914 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0;
916 /* Don't permit shared writable mappings on read-only descriptors. */
917 if (writecnt && (maxprot & VM_PROT_WRITE) == 0)
919 maxprot &= cap_maxprot;
921 /* See comment in vn_mmap(). */
926 foff < 0 || foff > OFF_MAX - objsize)
930 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
935 mtx_lock(&shm_timestamp_lock);
936 vfs_timestamp(&shmfd->shm_atime);
937 mtx_unlock(&shm_timestamp_lock);
938 vm_object_reference(shmfd->shm_object);
941 vm_pager_update_writecount(shmfd->shm_object, 0, objsize);
942 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
943 shmfd->shm_object, foff, writecnt, td);
946 vm_pager_release_writecount(shmfd->shm_object, 0,
948 vm_object_deallocate(shmfd->shm_object);
954 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
962 mtx_lock(&shm_timestamp_lock);
964 * SUSv4 says that x bits of permission need not be affected.
965 * Be consistent with our shm_open there.
968 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
972 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
973 shmfd->shm_gid, VADMIN, active_cred, NULL);
976 shmfd->shm_mode = mode & ACCESSPERMS;
978 mtx_unlock(&shm_timestamp_lock);
983 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
991 mtx_lock(&shm_timestamp_lock);
993 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
997 if (uid == (uid_t)-1)
998 uid = shmfd->shm_uid;
999 if (gid == (gid_t)-1)
1000 gid = shmfd->shm_gid;
1001 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1002 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1003 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
1005 shmfd->shm_uid = uid;
1006 shmfd->shm_gid = gid;
1008 mtx_unlock(&shm_timestamp_lock);
1013 * Helper routines to allow the backing object of a shared memory file
1014 * descriptor to be mapped in the kernel.
1017 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1019 struct shmfd *shmfd;
1020 vm_offset_t kva, ofs;
1024 if (fp->f_type != DTYPE_SHM)
1027 obj = shmfd->shm_object;
1028 VM_OBJECT_WLOCK(obj);
1030 * XXXRW: This validation is probably insufficient, and subject to
1031 * sign errors. It should be fixed.
1033 if (offset >= shmfd->shm_size ||
1034 offset + size > round_page(shmfd->shm_size)) {
1035 VM_OBJECT_WUNLOCK(obj);
1039 shmfd->shm_kmappings++;
1040 vm_object_reference_locked(obj);
1041 VM_OBJECT_WUNLOCK(obj);
1043 /* Map the object into the kernel_map and wire it. */
1044 kva = vm_map_min(kernel_map);
1045 ofs = offset & PAGE_MASK;
1046 offset = trunc_page(offset);
1047 size = round_page(size + ofs);
1048 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1049 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1050 VM_PROT_READ | VM_PROT_WRITE, 0);
1051 if (rv == KERN_SUCCESS) {
1052 rv = vm_map_wire(kernel_map, kva, kva + size,
1053 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1054 if (rv == KERN_SUCCESS) {
1055 *memp = (void *)(kva + ofs);
1058 vm_map_remove(kernel_map, kva, kva + size);
1060 vm_object_deallocate(obj);
1062 /* On failure, drop our mapping reference. */
1063 VM_OBJECT_WLOCK(obj);
1064 shmfd->shm_kmappings--;
1065 VM_OBJECT_WUNLOCK(obj);
1067 return (vm_mmap_to_errno(rv));
1071 * We require the caller to unmap the entire entry. This allows us to
1072 * safely decrement shm_kmappings when a mapping is removed.
1075 shm_unmap(struct file *fp, void *mem, size_t size)
1077 struct shmfd *shmfd;
1078 vm_map_entry_t entry;
1079 vm_offset_t kva, ofs;
1087 if (fp->f_type != DTYPE_SHM)
1090 kva = (vm_offset_t)mem;
1091 ofs = kva & PAGE_MASK;
1092 kva = trunc_page(kva);
1093 size = round_page(size + ofs);
1095 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1096 &obj, &pindex, &prot, &wired);
1097 if (rv != KERN_SUCCESS)
1099 if (entry->start != kva || entry->end != kva + size) {
1100 vm_map_lookup_done(map, entry);
1103 vm_map_lookup_done(map, entry);
1104 if (obj != shmfd->shm_object)
1106 vm_map_remove(map, kva, kva + size);
1107 VM_OBJECT_WLOCK(obj);
1108 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1109 shmfd->shm_kmappings--;
1110 VM_OBJECT_WUNLOCK(obj);
1115 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1117 const char *path, *pr_path;
1121 sx_assert(&shm_dict_lock, SA_LOCKED);
1122 kif->kf_type = KF_TYPE_SHM;
1123 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1124 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1125 if (shmfd->shm_path != NULL) {
1126 if (shmfd->shm_path != NULL) {
1127 path = shmfd->shm_path;
1128 pr_path = curthread->td_ucred->cr_prison->pr_path;
1129 if (strcmp(pr_path, "/") != 0) {
1130 /* Return the jail-rooted pathname. */
1131 pr_pathlen = strlen(pr_path);
1132 visible = strncmp(path, pr_path, pr_pathlen)
1133 == 0 && path[pr_pathlen] == '/';
1134 if (list && !visible)
1139 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1146 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1147 struct filedesc *fdp __unused)
1151 sx_slock(&shm_dict_lock);
1152 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1153 sx_sunlock(&shm_dict_lock);
1158 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
1160 struct shm_mapping *shmm;
1162 struct kinfo_file kif;
1167 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
1168 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
1171 sx_slock(&shm_dict_lock);
1172 for (i = 0; i < shm_hash + 1; i++) {
1173 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
1174 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
1181 if (req->oldptr != NULL &&
1182 kif.kf_structsize + curlen > req->oldlen)
1184 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
1188 curlen += kif.kf_structsize;
1191 sx_sunlock(&shm_dict_lock);
1192 error2 = sbuf_finish(&sb);
1194 return (error != 0 ? error : error2);
1197 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
1198 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
1199 NULL, 0, sysctl_posix_shm_list, "",