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 |
193 if (m->valid != VM_PAGE_BITS_ALL) {
195 if (vm_pager_has_page(obj, idx, NULL, NULL)) {
196 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
197 if (rv != VM_PAGER_OK) {
199 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
200 obj, idx, m->valid, rv);
201 vm_page_unwire_noq(m);
203 VM_OBJECT_WUNLOCK(obj);
207 vm_page_zero_invalid(m, TRUE);
210 VM_OBJECT_WUNLOCK(obj);
211 error = uiomove_fromphys(&m, offset, tlen, uio);
212 if (uio->uio_rw == UIO_WRITE && error == 0) {
213 VM_OBJECT_WLOCK(obj);
215 vm_pager_page_unswapped(m);
216 VM_OBJECT_WUNLOCK(obj);
218 vm_page_unwire(m, PQ_ACTIVE);
224 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
231 while ((resid = uio->uio_resid) > 0) {
232 if (obj_size <= uio->uio_offset)
234 len = MIN(obj_size - uio->uio_offset, resid);
237 error = uiomove_object_page(obj, len, uio);
238 if (error != 0 || resid == uio->uio_resid)
245 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
252 foffset = foffset_lock(fp, 0);
257 (offset > 0 && foffset > OFF_MAX - offset)) {
264 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
268 offset += shmfd->shm_size;
276 if (offset < 0 || offset > shmfd->shm_size)
279 td->td_uretoff.tdu_off = offset;
281 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
286 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
287 int flags, struct thread *td)
295 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
299 foffset_lock_uio(fp, uio, flags);
300 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
301 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
302 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
303 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
304 foffset_unlock_uio(fp, uio, flags);
309 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
310 int flags, struct thread *td)
318 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
322 foffset_lock_uio(fp, uio, flags);
323 if ((flags & FOF_OFFSET) == 0) {
324 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
327 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
328 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
331 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
332 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
333 foffset_unlock_uio(fp, uio, flags);
338 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
348 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
352 return (shm_dotruncate(shmfd, length));
356 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
364 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
365 * just like it would on an unlinked regular file
374 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
385 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
391 * Attempt to return sanish values for fstat() on a memory file
394 bzero(sb, sizeof(*sb));
395 sb->st_blksize = PAGE_SIZE;
396 sb->st_size = shmfd->shm_size;
397 sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
398 mtx_lock(&shm_timestamp_lock);
399 sb->st_atim = shmfd->shm_atime;
400 sb->st_ctim = shmfd->shm_ctime;
401 sb->st_mtim = shmfd->shm_mtime;
402 sb->st_birthtim = shmfd->shm_birthtime;
403 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
404 sb->st_uid = shmfd->shm_uid;
405 sb->st_gid = shmfd->shm_gid;
406 mtx_unlock(&shm_timestamp_lock);
407 sb->st_dev = shm_dev_ino;
408 sb->st_ino = shmfd->shm_ino;
409 sb->st_nlink = shmfd->shm_object->ref_count;
415 shm_close(struct file *fp, struct thread *td)
427 shm_dotruncate(struct shmfd *shmfd, off_t length)
431 vm_pindex_t idx, nobjsize;
435 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
436 object = shmfd->shm_object;
437 VM_OBJECT_WLOCK(object);
438 if (length == shmfd->shm_size) {
439 VM_OBJECT_WUNLOCK(object);
442 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
444 /* Are we shrinking? If so, trim the end. */
445 if (length < shmfd->shm_size) {
447 * Disallow any requests to shrink the size if this
448 * object is mapped into the kernel.
450 if (shmfd->shm_kmappings > 0) {
451 VM_OBJECT_WUNLOCK(object);
456 * Zero the truncated part of the last page.
458 base = length & PAGE_MASK;
460 idx = OFF_TO_IDX(length);
462 m = vm_page_lookup(object, idx);
464 if (vm_page_sleep_if_busy(m, "shmtrc"))
466 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
467 m = vm_page_alloc(object, idx,
468 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
471 rv = vm_pager_get_pages(object, &m, 1, NULL,
473 if (rv == VM_PAGER_OK) {
475 * Since the page was not resident,
476 * and therefore not recently
477 * accessed, immediately enqueue it
478 * for asynchronous laundering. The
479 * current operation is not regarded
486 VM_OBJECT_WUNLOCK(object);
491 pmap_zero_page_area(m, base, PAGE_SIZE - base);
492 KASSERT(m->valid == VM_PAGE_BITS_ALL,
493 ("shm_dotruncate: page %p is invalid", m));
495 vm_pager_page_unswapped(m);
498 delta = IDX_TO_OFF(object->size - nobjsize);
500 /* Toss in memory pages. */
501 if (nobjsize < object->size)
502 vm_object_page_remove(object, nobjsize, object->size,
505 /* Toss pages from swap. */
506 if (object->type == OBJT_SWAP)
507 swap_pager_freespace(object, nobjsize, delta);
509 /* Free the swap accounted for shm */
510 swap_release_by_cred(delta, object->cred);
511 object->charge -= delta;
513 /* Try to reserve additional swap space. */
514 delta = IDX_TO_OFF(nobjsize - object->size);
515 if (!swap_reserve_by_cred(delta, object->cred)) {
516 VM_OBJECT_WUNLOCK(object);
519 object->charge += delta;
521 shmfd->shm_size = length;
522 mtx_lock(&shm_timestamp_lock);
523 vfs_timestamp(&shmfd->shm_ctime);
524 shmfd->shm_mtime = shmfd->shm_ctime;
525 mtx_unlock(&shm_timestamp_lock);
526 object->size = nobjsize;
527 VM_OBJECT_WUNLOCK(object);
532 * shmfd object management including creation and reference counting
536 shm_alloc(struct ucred *ucred, mode_t mode)
540 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
542 shmfd->shm_uid = ucred->cr_uid;
543 shmfd->shm_gid = ucred->cr_gid;
544 shmfd->shm_mode = mode;
545 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL,
546 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
547 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
548 shmfd->shm_object->pg_color = 0;
549 VM_OBJECT_WLOCK(shmfd->shm_object);
550 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
551 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT);
552 VM_OBJECT_WUNLOCK(shmfd->shm_object);
553 vfs_timestamp(&shmfd->shm_birthtime);
554 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
555 shmfd->shm_birthtime;
556 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
557 refcount_init(&shmfd->shm_refs, 1);
558 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
559 rangelock_init(&shmfd->shm_rl);
561 mac_posixshm_init(shmfd);
562 mac_posixshm_create(ucred, shmfd);
569 shm_hold(struct shmfd *shmfd)
572 refcount_acquire(&shmfd->shm_refs);
577 shm_drop(struct shmfd *shmfd)
580 if (refcount_release(&shmfd->shm_refs)) {
582 mac_posixshm_destroy(shmfd);
584 rangelock_destroy(&shmfd->shm_rl);
585 mtx_destroy(&shmfd->shm_mtx);
586 vm_object_deallocate(shmfd->shm_object);
587 free(shmfd, M_SHMFD);
592 * Determine if the credentials have sufficient permissions for a
593 * specified combination of FREAD and FWRITE.
596 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
606 mtx_lock(&shm_timestamp_lock);
607 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
608 accmode, ucred, NULL);
609 mtx_unlock(&shm_timestamp_lock);
614 * Dictionary management. We maintain an in-kernel dictionary to map
615 * paths to shmfd objects. We use the FNV hash on the path to store
616 * the mappings in a hash table.
622 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
623 sx_init(&shm_dict_lock, "shm dictionary");
624 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
625 new_unrhdr64(&shm_ino_unr, 1);
626 shm_dev_ino = devfs_alloc_cdp_inode();
627 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
629 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
631 static struct shmfd *
632 shm_lookup(char *path, Fnv32_t fnv)
634 struct shm_mapping *map;
636 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
637 if (map->sm_fnv != fnv)
639 if (strcmp(map->sm_path, path) == 0)
640 return (map->sm_shmfd);
647 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
649 struct shm_mapping *map;
651 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
654 map->sm_shmfd = shm_hold(shmfd);
655 shmfd->shm_path = path;
656 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
660 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
662 struct shm_mapping *map;
665 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
666 if (map->sm_fnv != fnv)
668 if (strcmp(map->sm_path, path) == 0) {
670 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
674 error = shm_access(map->sm_shmfd, ucred,
678 map->sm_shmfd->shm_path = NULL;
679 LIST_REMOVE(map, sm_link);
680 shm_drop(map->sm_shmfd);
681 free(map->sm_path, M_SHMFD);
691 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
692 struct filecaps *fcaps)
694 struct filedesc *fdp;
704 #ifdef CAPABILITY_MODE
706 * shm_open(2) is only allowed for anonymous objects.
708 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
712 AUDIT_ARG_FFLAGS(flags);
713 AUDIT_ARG_MODE(mode);
715 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
718 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
721 fdp = td->td_proc->p_fd;
722 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
725 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
726 * by POSIX. We allow it to be unset here so that an in-kernel
727 * interface may be written as a thin layer around shm, optionally not
728 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
729 * in sys_shm_open() to keep this implementation compliant.
731 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
735 /* A SHM_ANON path pointer creates an anonymous object. */
736 if (userpath == SHM_ANON) {
737 /* A read-only anonymous object is pointless. */
738 if ((flags & O_ACCMODE) == O_RDONLY) {
743 shmfd = shm_alloc(td->td_ucred, cmode);
745 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
746 pr_path = td->td_ucred->cr_prison->pr_path;
748 /* Construct a full pathname for jailed callers. */
749 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
750 : strlcpy(path, pr_path, MAXPATHLEN);
751 error = copyinstr(userpath, path + pr_pathlen,
752 MAXPATHLEN - pr_pathlen, NULL);
754 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
757 /* Require paths to start with a '/' character. */
758 if (error == 0 && path[pr_pathlen] != '/')
767 AUDIT_ARG_UPATH1_CANON(path);
768 fnv = fnv_32_str(path, FNV1_32_INIT);
769 sx_xlock(&shm_dict_lock);
770 shmfd = shm_lookup(path, fnv);
772 /* Object does not yet exist, create it if requested. */
773 if (flags & O_CREAT) {
775 error = mac_posixshm_check_create(td->td_ucred,
779 shmfd = shm_alloc(td->td_ucred, cmode);
780 shm_insert(path, fnv, shmfd);
790 * Object already exists, obtain a new
791 * reference if requested and permitted.
794 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
798 error = mac_posixshm_check_open(td->td_ucred,
799 shmfd, FFLAGS(flags & O_ACCMODE));
802 error = shm_access(shmfd, td->td_ucred,
803 FFLAGS(flags & O_ACCMODE));
807 * Truncate the file back to zero length if
808 * O_TRUNC was specified and the object was
809 * opened with read/write.
812 (flags & (O_ACCMODE | O_TRUNC)) ==
813 (O_RDWR | O_TRUNC)) {
815 error = mac_posixshm_check_truncate(
816 td->td_ucred, fp->f_cred, shmfd);
819 shm_dotruncate(shmfd, 0);
824 sx_xunlock(&shm_dict_lock);
833 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
835 td->td_retval[0] = fd;
843 sys_shm_open(struct thread *td, struct shm_open_args *uap)
846 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode,
851 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
859 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
860 pr_path = td->td_ucred->cr_prison->pr_path;
861 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
862 : strlcpy(path, pr_path, MAXPATHLEN);
863 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
870 if (KTRPOINT(curthread, KTR_NAMEI))
873 AUDIT_ARG_UPATH1_CANON(path);
874 fnv = fnv_32_str(path, FNV1_32_INIT);
875 sx_xlock(&shm_dict_lock);
876 error = shm_remove(path, fnv, td->td_ucred);
877 sx_xunlock(&shm_dict_lock);
884 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
885 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
886 vm_ooffset_t foff, struct thread *td)
894 maxprot = VM_PROT_NONE;
896 /* FREAD should always be set. */
897 if ((fp->f_flag & FREAD) != 0)
898 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
899 if ((fp->f_flag & FWRITE) != 0)
900 maxprot |= VM_PROT_WRITE;
902 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0;
904 /* Don't permit shared writable mappings on read-only descriptors. */
905 if (writecnt && (maxprot & VM_PROT_WRITE) == 0)
907 maxprot &= cap_maxprot;
909 /* See comment in vn_mmap(). */
914 foff < 0 || foff > OFF_MAX - objsize)
918 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
923 mtx_lock(&shm_timestamp_lock);
924 vfs_timestamp(&shmfd->shm_atime);
925 mtx_unlock(&shm_timestamp_lock);
926 vm_object_reference(shmfd->shm_object);
929 vm_pager_update_writecount(shmfd->shm_object, 0, objsize);
930 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
931 shmfd->shm_object, foff, writecnt, td);
934 vm_pager_release_writecount(shmfd->shm_object, 0,
936 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_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1105 const char *path, *pr_path;
1109 sx_assert(&shm_dict_lock, SA_LOCKED);
1110 kif->kf_type = KF_TYPE_SHM;
1111 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1112 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1113 if (shmfd->shm_path != NULL) {
1114 if (shmfd->shm_path != NULL) {
1115 path = shmfd->shm_path;
1116 pr_path = curthread->td_ucred->cr_prison->pr_path;
1117 if (strcmp(pr_path, "/") != 0) {
1118 /* Return the jail-rooted pathname. */
1119 pr_pathlen = strlen(pr_path);
1120 visible = strncmp(path, pr_path, pr_pathlen)
1121 == 0 && path[pr_pathlen] == '/';
1122 if (list && !visible)
1127 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1134 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1135 struct filedesc *fdp __unused)
1139 sx_slock(&shm_dict_lock);
1140 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1141 sx_sunlock(&shm_dict_lock);
1146 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
1148 struct shm_mapping *shmm;
1150 struct kinfo_file kif;
1155 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
1156 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
1159 sx_slock(&shm_dict_lock);
1160 for (i = 0; i < shm_hash + 1; i++) {
1161 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
1162 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
1169 if (req->oldptr != NULL &&
1170 kif.kf_structsize + curlen > req->oldlen)
1172 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
1176 curlen += kif.kf_structsize;
1179 sx_sunlock(&shm_dict_lock);
1180 error2 = sbuf_finish(&sb);
1182 return (error != 0 ? error : error2);
1185 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
1186 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
1187 NULL, 0, sysctl_posix_shm_list, "",