2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
5 * Copyright 2020 The FreeBSD Foundation
8 * Portions of this software were developed by BAE Systems, the University of
9 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
10 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
11 * Computing (TC) research program.
13 * Portions of this software were developed by Konstantin Belousov
14 * under sponsorship from the FreeBSD Foundation.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * Support for shared swap-backed anonymous memory objects via
40 * shm_open(2), shm_rename(2), and shm_unlink(2).
41 * While most of the implementation is here, vm_mmap.c contains
42 * mapping logic changes.
44 * posixshmcontrol(1) allows users to inspect the state of the memory
45 * objects. Per-uid swap resource limit controls total amount of
46 * memory that user can consume for anonymous objects, including
50 #include <sys/cdefs.h>
51 __FBSDID("$FreeBSD$");
53 #include "opt_capsicum.h"
54 #include "opt_ktrace.h"
56 #include <sys/param.h>
57 #include <sys/capsicum.h>
59 #include <sys/fcntl.h>
61 #include <sys/filedesc.h>
62 #include <sys/filio.h>
63 #include <sys/fnv_hash.h>
64 #include <sys/kernel.h>
65 #include <sys/limits.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>
81 #include <sys/syscallsubr.h>
82 #include <sys/sysctl.h>
83 #include <sys/sysproto.h>
84 #include <sys/systm.h>
87 #include <sys/vmmeter.h>
88 #include <sys/vnode.h>
89 #include <sys/unistd.h>
92 #include <security/audit/audit.h>
93 #include <security/mac/mac_framework.h>
96 #include <vm/vm_param.h>
98 #include <vm/vm_extern.h>
99 #include <vm/vm_map.h>
100 #include <vm/vm_kern.h>
101 #include <vm/vm_object.h>
102 #include <vm/vm_page.h>
103 #include <vm/vm_pageout.h>
104 #include <vm/vm_pager.h>
105 #include <vm/swap_pager.h>
110 struct shmfd *sm_shmfd;
111 LIST_ENTRY(shm_mapping) sm_link;
114 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
115 static LIST_HEAD(, shm_mapping) *shm_dictionary;
116 static struct sx shm_dict_lock;
117 static struct mtx shm_timestamp_lock;
118 static u_long shm_hash;
119 static struct unrhdr64 shm_ino_unr;
120 static dev_t shm_dev_ino;
122 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
124 static void shm_init(void *arg);
125 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
126 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
127 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
128 static void shm_doremove(struct shm_mapping *map);
129 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length,
131 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
133 static int shm_copyin_path(struct thread *td, const char *userpath_in,
135 static int shm_deallocate(struct shmfd *shmfd, off_t *offset,
136 off_t *length, int flags);
138 static fo_rdwr_t shm_read;
139 static fo_rdwr_t shm_write;
140 static fo_truncate_t shm_truncate;
141 static fo_ioctl_t shm_ioctl;
142 static fo_stat_t shm_stat;
143 static fo_close_t shm_close;
144 static fo_chmod_t shm_chmod;
145 static fo_chown_t shm_chown;
146 static fo_seek_t shm_seek;
147 static fo_fill_kinfo_t shm_fill_kinfo;
148 static fo_mmap_t shm_mmap;
149 static fo_get_seals_t shm_get_seals;
150 static fo_add_seals_t shm_add_seals;
151 static fo_fallocate_t shm_fallocate;
152 static fo_fspacectl_t shm_fspacectl;
154 /* File descriptor operations. */
155 struct fileops shm_ops = {
157 .fo_write = shm_write,
158 .fo_truncate = shm_truncate,
159 .fo_ioctl = shm_ioctl,
160 .fo_poll = invfo_poll,
161 .fo_kqfilter = invfo_kqfilter,
163 .fo_close = shm_close,
164 .fo_chmod = shm_chmod,
165 .fo_chown = shm_chown,
166 .fo_sendfile = vn_sendfile,
168 .fo_fill_kinfo = shm_fill_kinfo,
170 .fo_get_seals = shm_get_seals,
171 .fo_add_seals = shm_add_seals,
172 .fo_fallocate = shm_fallocate,
173 .fo_fspacectl = shm_fspacectl,
174 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE,
177 FEATURE(posix_shm, "POSIX shared memory");
179 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
182 static int largepage_reclaim_tries = 1;
183 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries,
184 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0,
185 "Number of contig reclaims before giving up for default alloc policy");
188 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
193 int error, offset, rv;
195 idx = OFF_TO_IDX(uio->uio_offset);
196 offset = uio->uio_offset & PAGE_MASK;
197 tlen = MIN(PAGE_SIZE - offset, len);
199 rv = vm_page_grab_valid_unlocked(&m, obj, idx,
200 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT);
201 if (rv == VM_PAGER_OK)
205 * Read I/O without either a corresponding resident page or swap
206 * page: use zero_region. This is intended to avoid instantiating
207 * pages on read from a sparse region.
209 VM_OBJECT_WLOCK(obj);
210 m = vm_page_lookup(obj, idx);
211 if (uio->uio_rw == UIO_READ && m == NULL &&
212 !vm_pager_has_page(obj, idx, NULL, NULL)) {
213 VM_OBJECT_WUNLOCK(obj);
214 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
218 * Although the tmpfs vnode lock is held here, it is
219 * nonetheless safe to sleep waiting for a free page. The
220 * pageout daemon does not need to acquire the tmpfs vnode
221 * lock to page out tobj's pages because tobj is a OBJT_SWAP
224 rv = vm_page_grab_valid(&m, obj, idx,
225 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY);
226 if (rv != VM_PAGER_OK) {
227 VM_OBJECT_WUNLOCK(obj);
228 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n",
232 VM_OBJECT_WUNLOCK(obj);
235 error = uiomove_fromphys(&m, offset, tlen, uio);
236 if (uio->uio_rw == UIO_WRITE && error == 0)
237 vm_page_set_dirty(m);
245 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
252 while ((resid = uio->uio_resid) > 0) {
253 if (obj_size <= uio->uio_offset)
255 len = MIN(obj_size - uio->uio_offset, resid);
258 error = uiomove_object_page(obj, len, uio);
259 if (error != 0 || resid == uio->uio_resid)
265 static u_long count_largepages[MAXPAGESIZES];
268 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
269 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
271 vm_page_t m __diagused;
274 psind = object->un_pager.phys.data_val;
275 if (psind == 0 || pidx >= object->size)
276 return (VM_PAGER_FAIL);
277 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
280 * We only busy the first page in the superpage run. It is
281 * useless to busy whole run since we only remove full
282 * superpage, and it takes too long to busy e.g. 512 * 512 ==
283 * 262144 pages constituing 1G amd64 superage.
285 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
288 *last = *first + atop(pagesizes[psind]) - 1;
289 return (VM_PAGER_OK);
293 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
294 int *before, int *after)
298 psind = object->un_pager.phys.data_val;
299 if (psind == 0 || pindex >= object->size)
301 if (before != NULL) {
302 *before = pindex - rounddown2(pindex, pagesizes[psind] /
306 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
313 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
314 vm_ooffset_t foff, struct ucred *cred)
319 shm_largepage_phys_dtor(vm_object_t object)
323 psind = object->un_pager.phys.data_val;
325 atomic_subtract_long(&count_largepages[psind],
326 object->size / (pagesizes[psind] / PAGE_SIZE));
327 vm_wire_sub(object->size);
329 KASSERT(object->size == 0,
330 ("largepage phys obj %p not initialized bit size %#jx > 0",
331 object, (uintmax_t)object->size));
335 static const struct phys_pager_ops shm_largepage_phys_ops = {
336 .phys_pg_populate = shm_largepage_phys_populate,
337 .phys_pg_haspage = shm_largepage_phys_haspage,
338 .phys_pg_ctor = shm_largepage_phys_ctor,
339 .phys_pg_dtor = shm_largepage_phys_dtor,
343 shm_largepage(struct shmfd *shmfd)
345 return (shmfd->shm_object->type == OBJT_PHYS);
349 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
356 foffset = foffset_lock(fp, 0);
361 (offset > 0 && foffset > OFF_MAX - offset)) {
368 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
372 offset += shmfd->shm_size;
380 if (offset < 0 || offset > shmfd->shm_size)
383 td->td_uretoff.tdu_off = offset;
385 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
390 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
391 int flags, struct thread *td)
399 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
403 foffset_lock_uio(fp, uio, flags);
404 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
405 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
406 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
407 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
408 foffset_unlock_uio(fp, uio, flags);
413 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
414 int flags, struct thread *td)
423 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
427 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0)
429 foffset_lock_uio(fp, uio, flags);
430 if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
432 * Overflow is only an error if we're supposed to expand on
433 * write. Otherwise, we'll just truncate the write to the
434 * size of the file, which can only grow up to OFF_MAX.
436 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
437 foffset_unlock_uio(fp, uio, flags);
441 size = shmfd->shm_size;
443 size = uio->uio_offset + uio->uio_resid;
445 if ((flags & FOF_OFFSET) == 0) {
446 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
449 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
450 size, &shmfd->shm_mtx);
452 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
456 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
457 size > shmfd->shm_size) {
458 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
461 error = uiomove_object(shmfd->shm_object,
462 shmfd->shm_size, uio);
464 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
465 foffset_unlock_uio(fp, uio, flags);
470 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
480 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
484 return (shm_dotruncate(shmfd, length));
488 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
492 struct shm_largepage_conf *conf;
500 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
501 * just like it would on an unlinked regular file
505 if (!shm_largepage(shmfd))
508 if (shmfd->shm_lp_psind != 0 &&
509 conf->psind != shmfd->shm_lp_psind)
511 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
512 pagesizes[conf->psind] == 0)
514 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
515 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
516 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD)
519 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
521 shmfd->shm_lp_psind = conf->psind;
522 shmfd->shm_lp_alloc_policy = conf->alloc_policy;
523 shmfd->shm_object->un_pager.phys.data_val = conf->psind;
524 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
527 if (!shm_largepage(shmfd))
530 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX,
532 conf->psind = shmfd->shm_lp_psind;
533 conf->alloc_policy = shmfd->shm_lp_alloc_policy;
534 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
542 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
552 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
558 * Attempt to return sanish values for fstat() on a memory file
561 bzero(sb, sizeof(*sb));
562 sb->st_blksize = PAGE_SIZE;
563 sb->st_size = shmfd->shm_size;
564 sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
565 mtx_lock(&shm_timestamp_lock);
566 sb->st_atim = shmfd->shm_atime;
567 sb->st_ctim = shmfd->shm_ctime;
568 sb->st_mtim = shmfd->shm_mtime;
569 sb->st_birthtim = shmfd->shm_birthtime;
570 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
571 sb->st_uid = shmfd->shm_uid;
572 sb->st_gid = shmfd->shm_gid;
573 mtx_unlock(&shm_timestamp_lock);
574 sb->st_dev = shm_dev_ino;
575 sb->st_ino = shmfd->shm_ino;
576 sb->st_nlink = shmfd->shm_object->ref_count;
577 sb->st_blocks = shmfd->shm_object->size /
578 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT);
584 shm_close(struct file *fp, struct thread *td)
596 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
602 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
603 pr_path = td->td_ucred->cr_prison->pr_path;
605 /* Construct a full pathname for jailed callers. */
606 pr_pathlen = strcmp(pr_path, "/") ==
607 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
608 error = copyinstr(userpath_in, path + pr_pathlen,
609 MAXPATHLEN - pr_pathlen, NULL);
614 if (KTRPOINT(curthread, KTR_NAMEI))
618 /* Require paths to start with a '/' character. */
619 if (path[pr_pathlen] != '/') {
634 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
640 VM_OBJECT_ASSERT_WLOCKED(object);
641 KASSERT(base >= 0, ("%s: base %d", __func__, base));
642 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base,
646 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT);
648 MPASS(vm_page_all_valid(m));
649 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
650 m = vm_page_alloc(object, idx,
651 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
654 vm_object_pip_add(object, 1);
655 VM_OBJECT_WUNLOCK(object);
656 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
657 VM_OBJECT_WLOCK(object);
658 vm_object_pip_wakeup(object);
659 if (rv == VM_PAGER_OK) {
661 * Since the page was not resident, and therefore not
662 * recently accessed, immediately enqueue it for
663 * asynchronous laundering. The current operation is
664 * not regarded as an access.
669 VM_OBJECT_WUNLOCK(object);
674 pmap_zero_page_area(m, base, end - base);
675 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid",
677 vm_page_set_dirty(m);
685 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
688 vm_pindex_t nobjsize;
692 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
693 object = shmfd->shm_object;
694 VM_OBJECT_ASSERT_WLOCKED(object);
695 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
696 if (length == shmfd->shm_size)
698 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
700 /* Are we shrinking? If so, trim the end. */
701 if (length < shmfd->shm_size) {
702 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
706 * Disallow any requests to shrink the size if this
707 * object is mapped into the kernel.
709 if (shmfd->shm_kmappings > 0)
713 * Zero the truncated part of the last page.
715 base = length & PAGE_MASK;
717 error = shm_partial_page_invalidate(object,
718 OFF_TO_IDX(length), base, PAGE_SIZE);
722 delta = IDX_TO_OFF(object->size - nobjsize);
724 if (nobjsize < object->size)
725 vm_object_page_remove(object, nobjsize, object->size,
728 /* Free the swap accounted for shm */
729 swap_release_by_cred(delta, object->cred);
730 object->charge -= delta;
732 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
735 /* Try to reserve additional swap space. */
736 delta = IDX_TO_OFF(nobjsize - object->size);
737 if (!swap_reserve_by_cred(delta, object->cred))
739 object->charge += delta;
741 shmfd->shm_size = length;
742 mtx_lock(&shm_timestamp_lock);
743 vfs_timestamp(&shmfd->shm_ctime);
744 shmfd->shm_mtime = shmfd->shm_ctime;
745 mtx_unlock(&shm_timestamp_lock);
746 object->size = nobjsize;
751 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
755 vm_pindex_t newobjsz;
756 vm_pindex_t oldobjsz __unused;
757 int aflags, error, i, psind, try;
759 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
760 object = shmfd->shm_object;
761 VM_OBJECT_ASSERT_WLOCKED(object);
762 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
764 oldobjsz = object->size;
765 newobjsz = OFF_TO_IDX(length);
766 if (length == shmfd->shm_size)
768 psind = shmfd->shm_lp_psind;
769 if (psind == 0 && length != 0)
771 if ((length & (pagesizes[psind] - 1)) != 0)
774 if (length < shmfd->shm_size) {
775 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
777 if (shmfd->shm_kmappings > 0)
779 return (ENOTSUP); /* Pages are unmanaged. */
781 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
782 object->size = newobjsz;
783 shmfd->shm_size = length;
788 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
791 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
792 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
793 aflags |= VM_ALLOC_WAITFAIL;
797 * Extend shmfd and object, keeping all already fully
798 * allocated large pages intact even on error, because dropped
799 * object lock might allowed mapping of them.
801 while (object->size < newobjsz) {
802 m = vm_page_alloc_contig(object, object->size, aflags,
803 pagesizes[psind] / PAGE_SIZE, 0, ~0,
807 VM_OBJECT_WUNLOCK(object);
808 if (shmfd->shm_lp_alloc_policy ==
809 SHM_LARGEPAGE_ALLOC_NOWAIT ||
810 (shmfd->shm_lp_alloc_policy ==
811 SHM_LARGEPAGE_ALLOC_DEFAULT &&
812 try >= largepage_reclaim_tries)) {
813 VM_OBJECT_WLOCK(object);
816 error = vm_page_reclaim_contig(aflags,
817 pagesizes[psind] / PAGE_SIZE, 0, ~0,
818 pagesizes[psind], 0) ? 0 :
819 vm_wait_intr(object);
821 VM_OBJECT_WLOCK(object);
825 VM_OBJECT_WLOCK(object);
829 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
830 if ((m[i].flags & PG_ZERO) == 0)
831 pmap_zero_page(&m[i]);
832 vm_page_valid(&m[i]);
833 vm_page_xunbusy(&m[i]);
835 object->size += OFF_TO_IDX(pagesizes[psind]);
836 shmfd->shm_size += pagesizes[psind];
837 atomic_add_long(&count_largepages[psind], 1);
838 vm_wire_add(atop(pagesizes[psind]));
844 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
848 VM_OBJECT_WLOCK(shmfd->shm_object);
849 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
850 length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
852 VM_OBJECT_WUNLOCK(shmfd->shm_object);
857 shm_dotruncate(struct shmfd *shmfd, off_t length)
862 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
864 error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
865 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
870 * shmfd object management including creation and reference counting
874 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
878 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
880 shmfd->shm_uid = ucred->cr_uid;
881 shmfd->shm_gid = ucred->cr_gid;
882 shmfd->shm_mode = mode;
884 shmfd->shm_object = phys_pager_allocate(NULL,
885 &shm_largepage_phys_ops, NULL, shmfd->shm_size,
886 VM_PROT_DEFAULT, 0, ucred);
887 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
889 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL,
890 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
892 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
893 vfs_timestamp(&shmfd->shm_birthtime);
894 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
895 shmfd->shm_birthtime;
896 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
897 refcount_init(&shmfd->shm_refs, 1);
898 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
899 rangelock_init(&shmfd->shm_rl);
901 mac_posixshm_init(shmfd);
902 mac_posixshm_create(ucred, shmfd);
909 shm_hold(struct shmfd *shmfd)
912 refcount_acquire(&shmfd->shm_refs);
917 shm_drop(struct shmfd *shmfd)
920 if (refcount_release(&shmfd->shm_refs)) {
922 mac_posixshm_destroy(shmfd);
924 rangelock_destroy(&shmfd->shm_rl);
925 mtx_destroy(&shmfd->shm_mtx);
926 vm_object_deallocate(shmfd->shm_object);
927 free(shmfd, M_SHMFD);
932 * Determine if the credentials have sufficient permissions for a
933 * specified combination of FREAD and FWRITE.
936 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
946 mtx_lock(&shm_timestamp_lock);
947 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
949 mtx_unlock(&shm_timestamp_lock);
959 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
960 sx_init(&shm_dict_lock, "shm dictionary");
961 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
962 new_unrhdr64(&shm_ino_unr, 1);
963 shm_dev_ino = devfs_alloc_cdp_inode();
964 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
966 for (i = 1; i < MAXPAGESIZES; i++) {
967 if (pagesizes[i] == 0)
969 #define M (1024 * 1024)
971 if (pagesizes[i] >= G)
972 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
973 else if (pagesizes[i] >= M)
974 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
976 snprintf(name, sizeof(name), "%lu", pagesizes[i]);
979 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
980 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
981 "number of non-transient largepages allocated");
984 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
987 * Remove all shared memory objects that belong to a prison.
990 shm_remove_prison(struct prison *pr)
992 struct shm_mapping *shmm, *tshmm;
995 sx_xlock(&shm_dict_lock);
996 for (i = 0; i < shm_hash + 1; i++) {
997 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
998 if (shmm->sm_shmfd->shm_object->cred &&
999 shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1003 sx_xunlock(&shm_dict_lock);
1007 * Dictionary management. We maintain an in-kernel dictionary to map
1008 * paths to shmfd objects. We use the FNV hash on the path to store
1009 * the mappings in a hash table.
1011 static struct shmfd *
1012 shm_lookup(char *path, Fnv32_t fnv)
1014 struct shm_mapping *map;
1016 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1017 if (map->sm_fnv != fnv)
1019 if (strcmp(map->sm_path, path) == 0)
1020 return (map->sm_shmfd);
1027 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1029 struct shm_mapping *map;
1031 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1032 map->sm_path = path;
1034 map->sm_shmfd = shm_hold(shmfd);
1035 shmfd->shm_path = path;
1036 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1040 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1042 struct shm_mapping *map;
1045 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1046 if (map->sm_fnv != fnv)
1048 if (strcmp(map->sm_path, path) == 0) {
1050 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1054 error = shm_access(map->sm_shmfd, ucred,
1067 shm_doremove(struct shm_mapping *map)
1069 map->sm_shmfd->shm_path = NULL;
1070 LIST_REMOVE(map, sm_link);
1071 shm_drop(map->sm_shmfd);
1072 free(map->sm_path, M_SHMFD);
1077 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1078 int shmflags, struct filecaps *fcaps, const char *name __unused)
1080 struct pwddesc *pdp;
1081 struct shmfd *shmfd;
1087 int error, fd, initial_seals;
1090 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1091 SHM_LARGEPAGE)) != 0)
1094 initial_seals = F_SEAL_SEAL;
1095 if ((shmflags & SHM_ALLOW_SEALING) != 0)
1096 initial_seals &= ~F_SEAL_SEAL;
1098 #ifdef CAPABILITY_MODE
1100 * shm_open(2) is only allowed for anonymous objects.
1102 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
1106 AUDIT_ARG_FFLAGS(flags);
1107 AUDIT_ARG_MODE(mode);
1109 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1112 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
1115 largepage = (shmflags & SHM_LARGEPAGE) != 0;
1116 if (largepage && !PMAP_HAS_LARGEPAGES)
1120 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
1121 * If the decision is made later to allow additional seals, care must be
1122 * taken below to ensure that the seals are properly set if the shmfd
1123 * already existed -- this currently assumes that only F_SEAL_SEAL can
1124 * be set and doesn't take further precautions to ensure the validity of
1125 * the seals being added with respect to current mappings.
1127 if ((initial_seals & ~F_SEAL_SEAL) != 0)
1130 pdp = td->td_proc->p_pd;
1131 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1134 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1135 * by POSIX. We allow it to be unset here so that an in-kernel
1136 * interface may be written as a thin layer around shm, optionally not
1137 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
1138 * in sys_shm_open() to keep this implementation compliant.
1140 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1144 /* A SHM_ANON path pointer creates an anonymous object. */
1145 if (userpath == SHM_ANON) {
1146 /* A read-only anonymous object is pointless. */
1147 if ((flags & O_ACCMODE) == O_RDONLY) {
1148 fdclose(td, fp, fd);
1152 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1153 shmfd->shm_seals = initial_seals;
1154 shmfd->shm_flags = shmflags;
1156 error = shm_copyin_path(td, userpath, &path);
1158 fdclose(td, fp, fd);
1163 AUDIT_ARG_UPATH1_CANON(path);
1164 fnv = fnv_32_str(path, FNV1_32_INIT);
1165 sx_xlock(&shm_dict_lock);
1166 shmfd = shm_lookup(path, fnv);
1167 if (shmfd == NULL) {
1168 /* Object does not yet exist, create it if requested. */
1169 if (flags & O_CREAT) {
1171 error = mac_posixshm_check_create(td->td_ucred,
1175 shmfd = shm_alloc(td->td_ucred, cmode,
1177 shmfd->shm_seals = initial_seals;
1178 shmfd->shm_flags = shmflags;
1179 shm_insert(path, fnv, shmfd);
1184 free(path, M_SHMFD);
1188 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
1192 * kern_shm_open() likely shouldn't ever error out on
1193 * trying to set a seal that already exists, unlike
1194 * F_ADD_SEALS. This would break terribly as
1195 * shm_open(2) actually sets F_SEAL_SEAL to maintain
1196 * historical behavior where the underlying file could
1199 initial_seals &= ~shmfd->shm_seals;
1202 * Object already exists, obtain a new
1203 * reference if requested and permitted.
1205 free(path, M_SHMFD);
1208 * initial_seals can't set additional seals if we've
1209 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
1210 * then we've already removed that one from
1211 * initial_seals. This is currently redundant as we
1212 * only allow setting F_SEAL_SEAL at creation time, but
1213 * it's cheap to check and decreases the effort required
1214 * to allow additional seals.
1216 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1219 else if ((flags & (O_CREAT | O_EXCL)) ==
1222 else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1226 error = mac_posixshm_check_open(td->td_ucred,
1227 shmfd, FFLAGS(flags & O_ACCMODE));
1230 error = shm_access(shmfd, td->td_ucred,
1231 FFLAGS(flags & O_ACCMODE));
1235 * Truncate the file back to zero length if
1236 * O_TRUNC was specified and the object was
1237 * opened with read/write.
1240 (flags & (O_ACCMODE | O_TRUNC)) ==
1241 (O_RDWR | O_TRUNC)) {
1242 VM_OBJECT_WLOCK(shmfd->shm_object);
1244 error = mac_posixshm_check_truncate(
1245 td->td_ucred, fp->f_cred, shmfd);
1248 error = shm_dotruncate_locked(shmfd, 0,
1250 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1254 * Currently we only allow F_SEAL_SEAL to be
1255 * set initially. As noted above, this would
1256 * need to be reworked should that change.
1258 shmfd->shm_seals |= initial_seals;
1261 rangelock_unlock(&shmfd->shm_rl, rl_cookie,
1264 sx_xunlock(&shm_dict_lock);
1267 fdclose(td, fp, fd);
1273 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1275 td->td_retval[0] = fd;
1282 #ifdef COMPAT_FREEBSD12
1284 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1287 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1293 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1299 error = shm_copyin_path(td, uap->path, &path);
1303 AUDIT_ARG_UPATH1_CANON(path);
1304 fnv = fnv_32_str(path, FNV1_32_INIT);
1305 sx_xlock(&shm_dict_lock);
1306 error = shm_remove(path, fnv, td->td_ucred);
1307 sx_xunlock(&shm_dict_lock);
1308 free(path, M_SHMFD);
1314 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1316 char *path_from = NULL, *path_to = NULL;
1317 Fnv32_t fnv_from, fnv_to;
1318 struct shmfd *fd_from;
1319 struct shmfd *fd_to;
1324 AUDIT_ARG_FFLAGS(flags);
1327 * Make sure the user passed only valid flags.
1328 * If you add a new flag, please add a new term here.
1331 SHM_RENAME_NOREPLACE |
1339 * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1340 * force the user to choose one or the other.
1342 if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1343 (flags & SHM_RENAME_EXCHANGE) != 0) {
1348 /* Renaming to or from anonymous makes no sense */
1349 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1354 error = shm_copyin_path(td, uap->path_from, &path_from);
1358 error = shm_copyin_path(td, uap->path_to, &path_to);
1362 AUDIT_ARG_UPATH1_CANON(path_from);
1363 AUDIT_ARG_UPATH2_CANON(path_to);
1365 /* Rename with from/to equal is a no-op */
1366 if (strcmp(path_from, path_to) == 0)
1369 fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1370 fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1372 sx_xlock(&shm_dict_lock);
1374 fd_from = shm_lookup(path_from, fnv_from);
1375 if (fd_from == NULL) {
1380 fd_to = shm_lookup(path_to, fnv_to);
1381 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1387 * Unconditionally prevents shm_remove from invalidating the 'from'
1391 error = shm_remove(path_from, fnv_from, td->td_ucred);
1394 * One of my assumptions failed if ENOENT (e.g. locking didn't
1397 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1405 * If we are exchanging, we need to ensure the shm_remove below
1406 * doesn't invalidate the dest shm's state.
1408 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1412 * NOTE: if path_to is not already in the hash, c'est la vie;
1413 * it simply means we have nothing already at path_to to unlink.
1414 * That is the ENOENT case.
1416 * If we somehow don't have access to unlink this guy, but
1417 * did for the shm at path_from, then relink the shm to path_from
1418 * and abort with EACCES.
1420 * All other errors: that is weird; let's relink and abort the
1423 error = shm_remove(path_to, fnv_to, td->td_ucred);
1424 if (error != 0 && error != ENOENT) {
1425 shm_insert(path_from, fnv_from, fd_from);
1427 /* Don't free path_from now, since the hash references it */
1434 shm_insert(path_to, fnv_to, fd_from);
1436 /* Don't free path_to now, since the hash references it */
1439 /* We kept a ref when we removed, and incremented again in insert */
1441 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1442 fd_from->shm_refs));
1444 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1445 shm_insert(path_from, fnv_from, fd_to);
1448 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1453 sx_xunlock(&shm_dict_lock);
1456 free(path_from, M_SHMFD);
1457 free(path_to, M_SHMFD);
1462 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1463 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1464 vm_ooffset_t foff, struct thread *td)
1466 struct vmspace *vms;
1467 vm_map_entry_t next_entry, prev_entry;
1468 vm_offset_t align, mask, maxaddr;
1469 int docow, error, rv, try;
1472 if (shmfd->shm_lp_psind == 0)
1475 /* MAP_PRIVATE is disabled */
1476 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1481 MAP_ALIGNMENT_MASK)) != 0)
1484 vms = td->td_proc->p_vmspace;
1485 curmap = map == &vms->vm_map;
1487 error = kern_mmap_racct_check(td, map, size);
1492 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1493 docow |= MAP_INHERIT_SHARE;
1494 if ((flags & MAP_NOCORE) != 0)
1495 docow |= MAP_DISABLE_COREDUMP;
1497 mask = pagesizes[shmfd->shm_lp_psind] - 1;
1498 if ((foff & mask) != 0)
1500 maxaddr = vm_map_max(map);
1502 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1503 maxaddr = MAP_32BIT_MAX_ADDR;
1505 if (size == 0 || (size & mask) != 0 ||
1506 (*addr != 0 && ((*addr & mask) != 0 ||
1507 *addr + size < *addr || *addr + size > maxaddr)))
1510 align = flags & MAP_ALIGNMENT_MASK;
1512 align = pagesizes[shmfd->shm_lp_psind];
1513 } else if (align == MAP_ALIGNED_SUPER) {
1514 if (shmfd->shm_lp_psind != 1)
1516 align = pagesizes[1];
1518 align >>= MAP_ALIGNMENT_SHIFT;
1519 align = 1ULL << align;
1520 /* Also handles overflow. */
1521 if (align < pagesizes[shmfd->shm_lp_psind])
1526 if ((flags & MAP_FIXED) == 0) {
1528 if (curmap && (*addr == 0 ||
1529 (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1530 *addr < round_page((vm_offset_t)vms->vm_daddr +
1531 lim_max(td, RLIMIT_DATA))))) {
1532 *addr = roundup2((vm_offset_t)vms->vm_daddr +
1533 lim_max(td, RLIMIT_DATA),
1534 pagesizes[shmfd->shm_lp_psind]);
1537 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1538 if (rv != KERN_SUCCESS) {
1541 *addr = vm_map_min(map);
1542 if ((*addr & mask) != 0)
1543 *addr = (*addr + mask) & mask;
1548 } else if ((flags & MAP_EXCL) == 0) {
1549 rv = vm_map_delete(map, *addr, *addr + size);
1550 if (rv != KERN_SUCCESS)
1554 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1556 next_entry = vm_map_entry_succ(prev_entry);
1557 if (next_entry->start < *addr + size)
1561 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1562 prot, max_prot, docow);
1564 error = vm_mmap_to_errno(rv);
1571 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1572 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
1573 vm_ooffset_t foff, struct thread *td)
1575 struct shmfd *shmfd;
1582 maxprot = VM_PROT_NONE;
1584 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize,
1586 /* FREAD should always be set. */
1587 if ((fp->f_flag & FREAD) != 0)
1588 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1591 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1592 * mapping with a write seal applied. Private mappings are always
1595 if ((flags & MAP_SHARED) == 0) {
1596 cap_maxprot |= VM_PROT_WRITE;
1597 maxprot |= VM_PROT_WRITE;
1600 if ((fp->f_flag & FWRITE) != 0 &&
1601 (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1602 maxprot |= VM_PROT_WRITE;
1605 * Any mappings from a writable descriptor may be upgraded to
1606 * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1607 * applied between the open and subsequent mmap(2). We want to
1608 * reject application of a write seal as long as any such
1609 * mapping exists so that the seal cannot be trivially bypassed.
1611 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1612 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1617 maxprot &= cap_maxprot;
1619 /* See comment in vn_mmap(). */
1622 objsize > OFF_MAX ||
1624 foff > OFF_MAX - objsize) {
1630 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1635 mtx_lock(&shm_timestamp_lock);
1636 vfs_timestamp(&shmfd->shm_atime);
1637 mtx_unlock(&shm_timestamp_lock);
1638 vm_object_reference(shmfd->shm_object);
1640 if (shm_largepage(shmfd)) {
1642 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1643 maxprot, flags, foff, td);
1646 vm_pager_update_writecount(shmfd->shm_object, 0,
1649 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1650 shmfd->shm_object, foff, writecnt, td);
1654 vm_pager_release_writecount(shmfd->shm_object, 0,
1656 vm_object_deallocate(shmfd->shm_object);
1659 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
1664 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1667 struct shmfd *shmfd;
1672 mtx_lock(&shm_timestamp_lock);
1674 * SUSv4 says that x bits of permission need not be affected.
1675 * Be consistent with our shm_open there.
1678 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1682 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1683 VADMIN, active_cred);
1686 shmfd->shm_mode = mode & ACCESSPERMS;
1688 mtx_unlock(&shm_timestamp_lock);
1693 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1696 struct shmfd *shmfd;
1701 mtx_lock(&shm_timestamp_lock);
1703 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1707 if (uid == (uid_t)-1)
1708 uid = shmfd->shm_uid;
1709 if (gid == (gid_t)-1)
1710 gid = shmfd->shm_gid;
1711 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1712 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1713 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1715 shmfd->shm_uid = uid;
1716 shmfd->shm_gid = gid;
1718 mtx_unlock(&shm_timestamp_lock);
1723 * Helper routines to allow the backing object of a shared memory file
1724 * descriptor to be mapped in the kernel.
1727 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1729 struct shmfd *shmfd;
1730 vm_offset_t kva, ofs;
1734 if (fp->f_type != DTYPE_SHM)
1737 obj = shmfd->shm_object;
1738 VM_OBJECT_WLOCK(obj);
1740 * XXXRW: This validation is probably insufficient, and subject to
1741 * sign errors. It should be fixed.
1743 if (offset >= shmfd->shm_size ||
1744 offset + size > round_page(shmfd->shm_size)) {
1745 VM_OBJECT_WUNLOCK(obj);
1749 shmfd->shm_kmappings++;
1750 vm_object_reference_locked(obj);
1751 VM_OBJECT_WUNLOCK(obj);
1753 /* Map the object into the kernel_map and wire it. */
1754 kva = vm_map_min(kernel_map);
1755 ofs = offset & PAGE_MASK;
1756 offset = trunc_page(offset);
1757 size = round_page(size + ofs);
1758 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1759 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1760 VM_PROT_READ | VM_PROT_WRITE, 0);
1761 if (rv == KERN_SUCCESS) {
1762 rv = vm_map_wire(kernel_map, kva, kva + size,
1763 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1764 if (rv == KERN_SUCCESS) {
1765 *memp = (void *)(kva + ofs);
1768 vm_map_remove(kernel_map, kva, kva + size);
1770 vm_object_deallocate(obj);
1772 /* On failure, drop our mapping reference. */
1773 VM_OBJECT_WLOCK(obj);
1774 shmfd->shm_kmappings--;
1775 VM_OBJECT_WUNLOCK(obj);
1777 return (vm_mmap_to_errno(rv));
1781 * We require the caller to unmap the entire entry. This allows us to
1782 * safely decrement shm_kmappings when a mapping is removed.
1785 shm_unmap(struct file *fp, void *mem, size_t size)
1787 struct shmfd *shmfd;
1788 vm_map_entry_t entry;
1789 vm_offset_t kva, ofs;
1797 if (fp->f_type != DTYPE_SHM)
1800 kva = (vm_offset_t)mem;
1801 ofs = kva & PAGE_MASK;
1802 kva = trunc_page(kva);
1803 size = round_page(size + ofs);
1805 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1806 &obj, &pindex, &prot, &wired);
1807 if (rv != KERN_SUCCESS)
1809 if (entry->start != kva || entry->end != kva + size) {
1810 vm_map_lookup_done(map, entry);
1813 vm_map_lookup_done(map, entry);
1814 if (obj != shmfd->shm_object)
1816 vm_map_remove(map, kva, kva + size);
1817 VM_OBJECT_WLOCK(obj);
1818 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1819 shmfd->shm_kmappings--;
1820 VM_OBJECT_WUNLOCK(obj);
1825 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1827 const char *path, *pr_path;
1831 sx_assert(&shm_dict_lock, SA_LOCKED);
1832 kif->kf_type = KF_TYPE_SHM;
1833 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1834 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1835 if (shmfd->shm_path != NULL) {
1836 if (shmfd->shm_path != NULL) {
1837 path = shmfd->shm_path;
1838 pr_path = curthread->td_ucred->cr_prison->pr_path;
1839 if (strcmp(pr_path, "/") != 0) {
1840 /* Return the jail-rooted pathname. */
1841 pr_pathlen = strlen(pr_path);
1842 visible = strncmp(path, pr_path, pr_pathlen)
1843 == 0 && path[pr_pathlen] == '/';
1844 if (list && !visible)
1849 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1856 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1857 struct filedesc *fdp __unused)
1861 sx_slock(&shm_dict_lock);
1862 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1863 sx_sunlock(&shm_dict_lock);
1868 shm_add_seals(struct file *fp, int seals)
1870 struct shmfd *shmfd;
1872 vm_ooffset_t writemappings;
1877 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
1880 /* Even already-set seals should result in EPERM. */
1881 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
1885 nseals = seals & ~shmfd->shm_seals;
1886 if ((nseals & F_SEAL_WRITE) != 0) {
1887 if (shm_largepage(shmfd)) {
1893 * The rangelock above prevents writable mappings from being
1894 * added after we've started applying seals. The RLOCK here
1895 * is to avoid torn reads on ILP32 arches as unmapping/reducing
1896 * writemappings will be done without a rangelock.
1898 VM_OBJECT_RLOCK(shmfd->shm_object);
1899 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
1900 VM_OBJECT_RUNLOCK(shmfd->shm_object);
1901 /* kmappings are also writable */
1902 if (writemappings > 0) {
1907 shmfd->shm_seals |= nseals;
1909 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
1914 shm_get_seals(struct file *fp, int *seals)
1916 struct shmfd *shmfd;
1919 *seals = shmfd->shm_seals;
1924 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
1927 vm_pindex_t pistart, pi, piend;
1928 vm_ooffset_t off, len;
1929 int startofs, endofs, end;
1934 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
1935 if (off + len > shmfd->shm_size)
1936 len = shmfd->shm_size - off;
1937 object = shmfd->shm_object;
1938 startofs = off & PAGE_MASK;
1939 endofs = (off + len) & PAGE_MASK;
1940 pistart = OFF_TO_IDX(off);
1941 piend = OFF_TO_IDX(off + len);
1942 pi = OFF_TO_IDX(off + PAGE_MASK);
1945 /* Handle the case when offset is on or beyond shm size. */
1946 if ((off_t)len <= 0) {
1951 VM_OBJECT_WLOCK(object);
1953 if (startofs != 0) {
1954 end = pistart != piend ? PAGE_SIZE : endofs;
1955 error = shm_partial_page_invalidate(object, pistart, startofs,
1959 off += end - startofs;
1960 len -= end - startofs;
1964 vm_object_page_remove(object, pi, piend, 0);
1965 off += IDX_TO_OFF(piend - pi);
1966 len -= IDX_TO_OFF(piend - pi);
1969 if (endofs != 0 && pistart != piend) {
1970 error = shm_partial_page_invalidate(object, piend, 0, endofs);
1978 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1985 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
1986 struct ucred *active_cred, struct thread *td)
1989 struct shmfd *shmfd;
1993 /* This assumes that the caller already checked for overflow. */
1999 if (cmd != SPACECTL_DEALLOC || off < 0 || len <= 0 ||
2000 len > OFF_MAX - off || flags != 0)
2003 rl_cookie = rangelock_wlock(&shmfd->shm_rl, off, off + len,
2006 case SPACECTL_DEALLOC:
2007 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2011 error = shm_deallocate(shmfd, &off, &len, flags);
2016 __assert_unreachable();
2018 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
2024 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2027 struct shmfd *shmfd;
2031 /* This assumes that the caller already checked for overflow. */
2034 size = offset + len;
2037 * Just grab the rangelock for the range that we may be attempting to
2038 * grow, rather than blocking read/write for regions we won't be
2039 * touching while this (potential) resize is in progress. Other
2040 * attempts to resize the shmfd will have to take a write lock from 0 to
2041 * OFF_MAX, so this being potentially beyond the current usable range of
2042 * the shmfd is not necessarily a concern. If other mechanisms are
2043 * added to grow a shmfd, this may need to be re-evaluated.
2045 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size,
2047 if (size > shmfd->shm_size)
2048 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2049 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
2050 /* Translate to posix_fallocate(2) return value as needed. */
2051 if (error == ENOMEM)
2057 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2059 struct shm_mapping *shmm;
2061 struct kinfo_file kif;
2065 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2066 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2068 sx_slock(&shm_dict_lock);
2069 for (i = 0; i < shm_hash + 1; i++) {
2070 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2071 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2073 if (error == EPERM) {
2080 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2086 sx_sunlock(&shm_dict_lock);
2087 error2 = sbuf_finish(&sb);
2089 return (error != 0 ? error : error2);
2092 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2093 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2094 NULL, 0, sysctl_posix_shm_list, "",
2098 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2099 struct filecaps *caps)
2102 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
2106 * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2107 * caller, and libc will enforce it for the traditional shm_open() call. This
2108 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
2109 * interface also includes a 'name' argument that is currently unused, but could
2110 * potentially be exported later via some interface for debugging purposes.
2111 * From the kernel's perspective, it is optional. Individual consumers like
2112 * memfd_create() may require it in order to be compatible with other systems
2113 * implementing the same function.
2116 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2119 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2120 uap->shmflags, NULL, uap->name));