FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_shm.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
5 * Copyright 2020 The FreeBSD Foundation
6 * All rights reserved.
7 *
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.
12 *
13 * Portions of this software were developed by Konstantin Belousov
14 * under sponsorship from the FreeBSD Foundation.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
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.
24 *
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
35 * SUCH DAMAGE.
36 */
37
38 /*
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.
43 *
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
47 * shared.
48 */
49
50 #include <sys/cdefs.h>
51 __FBSDID("$FreeBSD$");
52
53 #include "opt_capsicum.h"
54 #include "opt_ktrace.h"
55
56 #include <sys/param.h>
57 #include <sys/capsicum.h>
58 #include <sys/conf.h>
59 #include <sys/fcntl.h>
60 #include <sys/file.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>
66 #include <sys/uio.h>
67 #include <sys/signal.h>
68 #include <sys/jail.h>
69 #include <sys/ktrace.h>
70 #include <sys/lock.h>
71 #include <sys/malloc.h>
72 #include <sys/mman.h>
73 #include <sys/mutex.h>
74 #include <sys/priv.h>
75 #include <sys/proc.h>
76 #include <sys/refcount.h>
77 #include <sys/resourcevar.h>
78 #include <sys/rwlock.h>
79 #include <sys/sbuf.h>
80 #include <sys/stat.h>
81 #include <sys/syscallsubr.h>
82 #include <sys/sysctl.h>
83 #include <sys/sysproto.h>
84 #include <sys/systm.h>
85 #include <sys/sx.h>
86 #include <sys/time.h>
87 #include <sys/vmmeter.h>
88 #include <sys/vnode.h>
89 #include <sys/unistd.h>
90 #include <sys/user.h>
91
92 #include <security/audit/audit.h>
93 #include <security/mac/mac_framework.h>
94
95 #include <vm/vm.h>
96 #include <vm/vm_param.h>
97 #include <vm/pmap.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>
106
107 struct shm_mapping {
108 char *sm_path;
109 Fnv32_t sm_fnv;
110 struct shmfd *sm_shmfd;
111 LIST_ENTRY(shm_mapping) sm_link;
112 };
113
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;
121
122 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
123
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,
130 void *rl_cookie);
131 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
132 void *rl_cookie);
133 static int shm_copyin_path(struct thread *td, const char *userpath_in,
134 char **path_out);
135 static int shm_deallocate(struct shmfd *shmfd, off_t *offset,
136 off_t *length, int flags);
137
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;
153
154 /* File descriptor operations. */
155 struct fileops shm_ops = {
156 .fo_read = shm_read,
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,
162 .fo_stat = shm_stat,
163 .fo_close = shm_close,
164 .fo_chmod = shm_chmod,
165 .fo_chown = shm_chown,
166 .fo_sendfile = vn_sendfile,
167 .fo_seek = shm_seek,
168 .fo_fill_kinfo = shm_fill_kinfo,
169 .fo_mmap = shm_mmap,
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,
175 };
176
177 FEATURE(posix_shm, "POSIX shared memory");
178
179 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
180 "");
181
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");
186
187 static int
188 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
189 {
190 vm_page_t m;
191 vm_pindex_t idx;
192 size_t tlen;
193 int error, offset, rv;
194
195 idx = OFF_TO_IDX(uio->uio_offset);
196 offset = uio->uio_offset & PAGE_MASK;
197 tlen = MIN(PAGE_SIZE - offset, len);
198
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)
202 goto found;
203
204 /*
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.
208 */
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));
215 }
216
217 /*
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
222 * type object.
223 */
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 if (bootverbose) {
229 printf("uiomove_object: vm_obj %p idx %jd "
230 "pager error %d\n", obj, idx, rv);
231 }
232 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO);
233 }
234 VM_OBJECT_WUNLOCK(obj);
235
236 found:
237 error = uiomove_fromphys(&m, offset, tlen, uio);
238 if (uio->uio_rw == UIO_WRITE && error == 0)
239 vm_page_set_dirty(m);
240 vm_page_activate(m);
241 vm_page_sunbusy(m);
242
243 return (error);
244 }
245
246 int
247 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
248 {
249 ssize_t resid;
250 size_t len;
251 int error;
252
253 error = 0;
254 while ((resid = uio->uio_resid) > 0) {
255 if (obj_size <= uio->uio_offset)
256 break;
257 len = MIN(obj_size - uio->uio_offset, resid);
258 if (len == 0)
259 break;
260 error = uiomove_object_page(obj, len, uio);
261 if (error != 0 || resid == uio->uio_resid)
262 break;
263 }
264 return (error);
265 }
266
267 static u_long count_largepages[MAXPAGESIZES];
268
269 static int
270 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
271 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
272 {
273 vm_page_t m __diagused;
274 int psind;
275
276 psind = object->un_pager.phys.data_val;
277 if (psind == 0 || pidx >= object->size)
278 return (VM_PAGER_FAIL);
279 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
280
281 /*
282 * We only busy the first page in the superpage run. It is
283 * useless to busy whole run since we only remove full
284 * superpage, and it takes too long to busy e.g. 512 * 512 ==
285 * 262144 pages constituing 1G amd64 superage.
286 */
287 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
288 MPASS(m != NULL);
289
290 *last = *first + atop(pagesizes[psind]) - 1;
291 return (VM_PAGER_OK);
292 }
293
294 static boolean_t
295 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
296 int *before, int *after)
297 {
298 int psind;
299
300 psind = object->un_pager.phys.data_val;
301 if (psind == 0 || pindex >= object->size)
302 return (FALSE);
303 if (before != NULL) {
304 *before = pindex - rounddown2(pindex, pagesizes[psind] /
305 PAGE_SIZE);
306 }
307 if (after != NULL) {
308 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
309 pindex;
310 }
311 return (TRUE);
312 }
313
314 static void
315 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
316 vm_ooffset_t foff, struct ucred *cred)
317 {
318 }
319
320 static void
321 shm_largepage_phys_dtor(vm_object_t object)
322 {
323 int psind;
324
325 psind = object->un_pager.phys.data_val;
326 if (psind != 0) {
327 atomic_subtract_long(&count_largepages[psind],
328 object->size / (pagesizes[psind] / PAGE_SIZE));
329 vm_wire_sub(object->size);
330 } else {
331 KASSERT(object->size == 0,
332 ("largepage phys obj %p not initialized bit size %#jx > 0",
333 object, (uintmax_t)object->size));
334 }
335 }
336
337 static const struct phys_pager_ops shm_largepage_phys_ops = {
338 .phys_pg_populate = shm_largepage_phys_populate,
339 .phys_pg_haspage = shm_largepage_phys_haspage,
340 .phys_pg_ctor = shm_largepage_phys_ctor,
341 .phys_pg_dtor = shm_largepage_phys_dtor,
342 };
343
344 bool
345 shm_largepage(struct shmfd *shmfd)
346 {
347 return (shmfd->shm_object->type == OBJT_PHYS);
348 }
349
350 static void
351 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size)
352 {
353 struct shmfd *shm;
354 vm_size_t c;
355
356 swap_pager_freespace(obj, start, size, &c);
357 if (c == 0)
358 return;
359
360 shm = obj->un_pager.swp.swp_priv;
361 if (shm == NULL)
362 return;
363 KASSERT(shm->shm_pages >= c,
364 ("shm %p pages %jd free %jd", shm,
365 (uintmax_t)shm->shm_pages, (uintmax_t)c));
366 shm->shm_pages -= c;
367 }
368
369 static void
370 shm_page_inserted(vm_object_t obj, vm_page_t m)
371 {
372 struct shmfd *shm;
373
374 shm = obj->un_pager.swp.swp_priv;
375 if (shm == NULL)
376 return;
377 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL))
378 shm->shm_pages += 1;
379 }
380
381 static void
382 shm_page_removed(vm_object_t obj, vm_page_t m)
383 {
384 struct shmfd *shm;
385
386 shm = obj->un_pager.swp.swp_priv;
387 if (shm == NULL)
388 return;
389 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) {
390 KASSERT(shm->shm_pages >= 1,
391 ("shm %p pages %jd free 1", shm,
392 (uintmax_t)shm->shm_pages));
393 shm->shm_pages -= 1;
394 }
395 }
396
397 static struct pagerops shm_swap_pager_ops = {
398 .pgo_kvme_type = KVME_TYPE_SWAP,
399 .pgo_freespace = shm_pager_freespace,
400 .pgo_page_inserted = shm_page_inserted,
401 .pgo_page_removed = shm_page_removed,
402 };
403 static int shmfd_pager_type = -1;
404
405 static int
406 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
407 {
408 struct shmfd *shmfd;
409 off_t foffset;
410 int error;
411
412 shmfd = fp->f_data;
413 foffset = foffset_lock(fp, 0);
414 error = 0;
415 switch (whence) {
416 case L_INCR:
417 if (foffset < 0 ||
418 (offset > 0 && foffset > OFF_MAX - offset)) {
419 error = EOVERFLOW;
420 break;
421 }
422 offset += foffset;
423 break;
424 case L_XTND:
425 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
426 error = EOVERFLOW;
427 break;
428 }
429 offset += shmfd->shm_size;
430 break;
431 case L_SET:
432 break;
433 default:
434 error = EINVAL;
435 }
436 if (error == 0) {
437 if (offset < 0 || offset > shmfd->shm_size)
438 error = EINVAL;
439 else
440 td->td_uretoff.tdu_off = offset;
441 }
442 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
443 return (error);
444 }
445
446 static int
447 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
448 int flags, struct thread *td)
449 {
450 struct shmfd *shmfd;
451 void *rl_cookie;
452 int error;
453
454 shmfd = fp->f_data;
455 #ifdef MAC
456 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
457 if (error)
458 return (error);
459 #endif
460 foffset_lock_uio(fp, uio, flags);
461 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
462 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
463 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
464 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
465 foffset_unlock_uio(fp, uio, flags);
466 return (error);
467 }
468
469 static int
470 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
471 int flags, struct thread *td)
472 {
473 struct shmfd *shmfd;
474 void *rl_cookie;
475 int error;
476 off_t size;
477
478 shmfd = fp->f_data;
479 #ifdef MAC
480 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
481 if (error)
482 return (error);
483 #endif
484 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0)
485 return (EINVAL);
486 foffset_lock_uio(fp, uio, flags);
487 if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
488 /*
489 * Overflow is only an error if we're supposed to expand on
490 * write. Otherwise, we'll just truncate the write to the
491 * size of the file, which can only grow up to OFF_MAX.
492 */
493 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
494 foffset_unlock_uio(fp, uio, flags);
495 return (EFBIG);
496 }
497
498 size = shmfd->shm_size;
499 } else {
500 size = uio->uio_offset + uio->uio_resid;
501 }
502 if ((flags & FOF_OFFSET) == 0) {
503 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
504 &shmfd->shm_mtx);
505 } else {
506 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
507 size, &shmfd->shm_mtx);
508 }
509 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
510 error = EPERM;
511 } else {
512 error = 0;
513 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
514 size > shmfd->shm_size) {
515 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
516 }
517 if (error == 0)
518 error = uiomove_object(shmfd->shm_object,
519 shmfd->shm_size, uio);
520 }
521 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
522 foffset_unlock_uio(fp, uio, flags);
523 return (error);
524 }
525
526 static int
527 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
528 struct thread *td)
529 {
530 struct shmfd *shmfd;
531 #ifdef MAC
532 int error;
533 #endif
534
535 shmfd = fp->f_data;
536 #ifdef MAC
537 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
538 if (error)
539 return (error);
540 #endif
541 return (shm_dotruncate(shmfd, length));
542 }
543
544 int
545 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
546 struct thread *td)
547 {
548 struct shmfd *shmfd;
549 struct shm_largepage_conf *conf;
550 void *rl_cookie;
551
552 shmfd = fp->f_data;
553 switch (com) {
554 case FIONBIO:
555 case FIOASYNC:
556 /*
557 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
558 * just like it would on an unlinked regular file
559 */
560 return (0);
561 case FIOSSHMLPGCNF:
562 if (!shm_largepage(shmfd))
563 return (ENOTTY);
564 conf = data;
565 if (shmfd->shm_lp_psind != 0 &&
566 conf->psind != shmfd->shm_lp_psind)
567 return (EINVAL);
568 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
569 pagesizes[conf->psind] == 0)
570 return (EINVAL);
571 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
572 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
573 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD)
574 return (EINVAL);
575
576 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
577 &shmfd->shm_mtx);
578 shmfd->shm_lp_psind = conf->psind;
579 shmfd->shm_lp_alloc_policy = conf->alloc_policy;
580 shmfd->shm_object->un_pager.phys.data_val = conf->psind;
581 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
582 return (0);
583 case FIOGSHMLPGCNF:
584 if (!shm_largepage(shmfd))
585 return (ENOTTY);
586 conf = data;
587 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX,
588 &shmfd->shm_mtx);
589 conf->psind = shmfd->shm_lp_psind;
590 conf->alloc_policy = shmfd->shm_lp_alloc_policy;
591 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
592 return (0);
593 default:
594 return (ENOTTY);
595 }
596 }
597
598 static int
599 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
600 {
601 struct shmfd *shmfd;
602 #ifdef MAC
603 int error;
604 #endif
605
606 shmfd = fp->f_data;
607
608 #ifdef MAC
609 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
610 if (error)
611 return (error);
612 #endif
613
614 /*
615 * Attempt to return sanish values for fstat() on a memory file
616 * descriptor.
617 */
618 bzero(sb, sizeof(*sb));
619 sb->st_blksize = PAGE_SIZE;
620 sb->st_size = shmfd->shm_size;
621 mtx_lock(&shm_timestamp_lock);
622 sb->st_atim = shmfd->shm_atime;
623 sb->st_ctim = shmfd->shm_ctime;
624 sb->st_mtim = shmfd->shm_mtime;
625 sb->st_birthtim = shmfd->shm_birthtime;
626 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
627 sb->st_uid = shmfd->shm_uid;
628 sb->st_gid = shmfd->shm_gid;
629 mtx_unlock(&shm_timestamp_lock);
630 sb->st_dev = shm_dev_ino;
631 sb->st_ino = shmfd->shm_ino;
632 sb->st_nlink = shmfd->shm_object->ref_count;
633 if (shm_largepage(shmfd)) {
634 sb->st_blocks = shmfd->shm_object->size /
635 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT);
636 } else {
637 sb->st_blocks = shmfd->shm_pages;
638 }
639
640 return (0);
641 }
642
643 static int
644 shm_close(struct file *fp, struct thread *td)
645 {
646 struct shmfd *shmfd;
647
648 shmfd = fp->f_data;
649 fp->f_data = NULL;
650 shm_drop(shmfd);
651
652 return (0);
653 }
654
655 static int
656 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
657 int error;
658 char *path;
659 const char *pr_path;
660 size_t pr_pathlen;
661
662 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
663 pr_path = td->td_ucred->cr_prison->pr_path;
664
665 /* Construct a full pathname for jailed callers. */
666 pr_pathlen = strcmp(pr_path, "/") ==
667 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
668 error = copyinstr(userpath_in, path + pr_pathlen,
669 MAXPATHLEN - pr_pathlen, NULL);
670 if (error != 0)
671 goto out;
672
673 #ifdef KTRACE
674 if (KTRPOINT(curthread, KTR_NAMEI))
675 ktrnamei(path);
676 #endif
677
678 /* Require paths to start with a '/' character. */
679 if (path[pr_pathlen] != '/') {
680 error = EINVAL;
681 goto out;
682 }
683
684 *path_out = path;
685
686 out:
687 if (error != 0)
688 free(path, M_SHMFD);
689
690 return (error);
691 }
692
693 static int
694 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
695 int end)
696 {
697 vm_page_t m;
698 int rv;
699
700 VM_OBJECT_ASSERT_WLOCKED(object);
701 KASSERT(base >= 0, ("%s: base %d", __func__, base));
702 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base,
703 end));
704
705 retry:
706 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT);
707 if (m != NULL) {
708 MPASS(vm_page_all_valid(m));
709 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
710 m = vm_page_alloc(object, idx,
711 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
712 if (m == NULL)
713 goto retry;
714 vm_object_pip_add(object, 1);
715 VM_OBJECT_WUNLOCK(object);
716 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
717 VM_OBJECT_WLOCK(object);
718 vm_object_pip_wakeup(object);
719 if (rv == VM_PAGER_OK) {
720 /*
721 * Since the page was not resident, and therefore not
722 * recently accessed, immediately enqueue it for
723 * asynchronous laundering. The current operation is
724 * not regarded as an access.
725 */
726 vm_page_launder(m);
727 } else {
728 vm_page_free(m);
729 VM_OBJECT_WUNLOCK(object);
730 return (EIO);
731 }
732 }
733 if (m != NULL) {
734 pmap_zero_page_area(m, base, end - base);
735 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid",
736 __func__, m));
737 vm_page_set_dirty(m);
738 vm_page_xunbusy(m);
739 }
740
741 return (0);
742 }
743
744 static int
745 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
746 {
747 vm_object_t object;
748 vm_pindex_t nobjsize;
749 vm_ooffset_t delta;
750 int base, error;
751
752 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
753 object = shmfd->shm_object;
754 VM_OBJECT_ASSERT_WLOCKED(object);
755 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
756 if (length == shmfd->shm_size)
757 return (0);
758 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
759
760 /* Are we shrinking? If so, trim the end. */
761 if (length < shmfd->shm_size) {
762 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
763 return (EPERM);
764
765 /*
766 * Disallow any requests to shrink the size if this
767 * object is mapped into the kernel.
768 */
769 if (shmfd->shm_kmappings > 0)
770 return (EBUSY);
771
772 /*
773 * Zero the truncated part of the last page.
774 */
775 base = length & PAGE_MASK;
776 if (base != 0) {
777 error = shm_partial_page_invalidate(object,
778 OFF_TO_IDX(length), base, PAGE_SIZE);
779 if (error)
780 return (error);
781 }
782 delta = IDX_TO_OFF(object->size - nobjsize);
783
784 if (nobjsize < object->size)
785 vm_object_page_remove(object, nobjsize, object->size,
786 0);
787
788 /* Free the swap accounted for shm */
789 swap_release_by_cred(delta, object->cred);
790 object->charge -= delta;
791 } else {
792 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
793 return (EPERM);
794
795 /* Try to reserve additional swap space. */
796 delta = IDX_TO_OFF(nobjsize - object->size);
797 if (!swap_reserve_by_cred(delta, object->cred))
798 return (ENOMEM);
799 object->charge += delta;
800 }
801 shmfd->shm_size = length;
802 mtx_lock(&shm_timestamp_lock);
803 vfs_timestamp(&shmfd->shm_ctime);
804 shmfd->shm_mtime = shmfd->shm_ctime;
805 mtx_unlock(&shm_timestamp_lock);
806 object->size = nobjsize;
807 return (0);
808 }
809
810 static int
811 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
812 {
813 vm_object_t object;
814 vm_page_t m;
815 vm_pindex_t newobjsz;
816 vm_pindex_t oldobjsz __unused;
817 int aflags, error, i, psind, try;
818
819 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
820 object = shmfd->shm_object;
821 VM_OBJECT_ASSERT_WLOCKED(object);
822 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
823
824 oldobjsz = object->size;
825 newobjsz = OFF_TO_IDX(length);
826 if (length == shmfd->shm_size)
827 return (0);
828 psind = shmfd->shm_lp_psind;
829 if (psind == 0 && length != 0)
830 return (EINVAL);
831 if ((length & (pagesizes[psind] - 1)) != 0)
832 return (EINVAL);
833
834 if (length < shmfd->shm_size) {
835 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
836 return (EPERM);
837 if (shmfd->shm_kmappings > 0)
838 return (EBUSY);
839 return (ENOTSUP); /* Pages are unmanaged. */
840 #if 0
841 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
842 object->size = newobjsz;
843 shmfd->shm_size = length;
844 return (0);
845 #endif
846 }
847
848 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
849 return (EPERM);
850
851 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
852 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
853 aflags |= VM_ALLOC_WAITFAIL;
854 try = 0;
855
856 /*
857 * Extend shmfd and object, keeping all already fully
858 * allocated large pages intact even on error, because dropped
859 * object lock might allowed mapping of them.
860 */
861 while (object->size < newobjsz) {
862 m = vm_page_alloc_contig(object, object->size, aflags,
863 pagesizes[psind] / PAGE_SIZE, 0, ~0,
864 pagesizes[psind], 0,
865 VM_MEMATTR_DEFAULT);
866 if (m == NULL) {
867 VM_OBJECT_WUNLOCK(object);
868 if (shmfd->shm_lp_alloc_policy ==
869 SHM_LARGEPAGE_ALLOC_NOWAIT ||
870 (shmfd->shm_lp_alloc_policy ==
871 SHM_LARGEPAGE_ALLOC_DEFAULT &&
872 try >= largepage_reclaim_tries)) {
873 VM_OBJECT_WLOCK(object);
874 return (ENOMEM);
875 }
876 error = vm_page_reclaim_contig(aflags,
877 pagesizes[psind] / PAGE_SIZE, 0, ~0,
878 pagesizes[psind], 0) ? 0 :
879 vm_wait_intr(object);
880 if (error != 0) {
881 VM_OBJECT_WLOCK(object);
882 return (error);
883 }
884 try++;
885 VM_OBJECT_WLOCK(object);
886 continue;
887 }
888 try = 0;
889 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
890 if ((m[i].flags & PG_ZERO) == 0)
891 pmap_zero_page(&m[i]);
892 vm_page_valid(&m[i]);
893 vm_page_xunbusy(&m[i]);
894 }
895 object->size += OFF_TO_IDX(pagesizes[psind]);
896 shmfd->shm_size += pagesizes[psind];
897 atomic_add_long(&count_largepages[psind], 1);
898 vm_wire_add(atop(pagesizes[psind]));
899 }
900 return (0);
901 }
902
903 static int
904 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
905 {
906 int error;
907
908 VM_OBJECT_WLOCK(shmfd->shm_object);
909 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
910 length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
911 rl_cookie);
912 VM_OBJECT_WUNLOCK(shmfd->shm_object);
913 return (error);
914 }
915
916 int
917 shm_dotruncate(struct shmfd *shmfd, off_t length)
918 {
919 void *rl_cookie;
920 int error;
921
922 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
923 &shmfd->shm_mtx);
924 error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
925 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
926 return (error);
927 }
928
929 /*
930 * shmfd object management including creation and reference counting
931 * routines.
932 */
933 struct shmfd *
934 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
935 {
936 struct shmfd *shmfd;
937 vm_object_t obj;
938
939 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
940 shmfd->shm_size = 0;
941 shmfd->shm_uid = ucred->cr_uid;
942 shmfd->shm_gid = ucred->cr_gid;
943 shmfd->shm_mode = mode;
944 if (largepage) {
945 shmfd->shm_object = phys_pager_allocate(NULL,
946 &shm_largepage_phys_ops, NULL, shmfd->shm_size,
947 VM_PROT_DEFAULT, 0, ucred);
948 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
949 } else {
950 obj = vm_pager_allocate(shmfd_pager_type, NULL,
951 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
952 VM_OBJECT_WLOCK(obj);
953 obj->un_pager.swp.swp_priv = shmfd;
954 VM_OBJECT_WUNLOCK(obj);
955 shmfd->shm_object = obj;
956 }
957 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
958 vfs_timestamp(&shmfd->shm_birthtime);
959 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
960 shmfd->shm_birthtime;
961 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
962 refcount_init(&shmfd->shm_refs, 1);
963 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
964 rangelock_init(&shmfd->shm_rl);
965 #ifdef MAC
966 mac_posixshm_init(shmfd);
967 mac_posixshm_create(ucred, shmfd);
968 #endif
969
970 return (shmfd);
971 }
972
973 struct shmfd *
974 shm_hold(struct shmfd *shmfd)
975 {
976
977 refcount_acquire(&shmfd->shm_refs);
978 return (shmfd);
979 }
980
981 void
982 shm_drop(struct shmfd *shmfd)
983 {
984 vm_object_t obj;
985
986 if (refcount_release(&shmfd->shm_refs)) {
987 #ifdef MAC
988 mac_posixshm_destroy(shmfd);
989 #endif
990 rangelock_destroy(&shmfd->shm_rl);
991 mtx_destroy(&shmfd->shm_mtx);
992 obj = shmfd->shm_object;
993 if (!shm_largepage(shmfd)) {
994 VM_OBJECT_WLOCK(obj);
995 obj->un_pager.swp.swp_priv = NULL;
996 VM_OBJECT_WUNLOCK(obj);
997 }
998 vm_object_deallocate(obj);
999 free(shmfd, M_SHMFD);
1000 }
1001 }
1002
1003 /*
1004 * Determine if the credentials have sufficient permissions for a
1005 * specified combination of FREAD and FWRITE.
1006 */
1007 int
1008 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
1009 {
1010 accmode_t accmode;
1011 int error;
1012
1013 accmode = 0;
1014 if (flags & FREAD)
1015 accmode |= VREAD;
1016 if (flags & FWRITE)
1017 accmode |= VWRITE;
1018 mtx_lock(&shm_timestamp_lock);
1019 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1020 accmode, ucred);
1021 mtx_unlock(&shm_timestamp_lock);
1022 return (error);
1023 }
1024
1025 static void
1026 shm_init(void *arg)
1027 {
1028 char name[32];
1029 int i;
1030
1031 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
1032 sx_init(&shm_dict_lock, "shm dictionary");
1033 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
1034 new_unrhdr64(&shm_ino_unr, 1);
1035 shm_dev_ino = devfs_alloc_cdp_inode();
1036 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
1037 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
1038 OBJT_SWAP);
1039 MPASS(shmfd_pager_type != -1);
1040
1041 for (i = 1; i < MAXPAGESIZES; i++) {
1042 if (pagesizes[i] == 0)
1043 break;
1044 #define M (1024 * 1024)
1045 #define G (1024 * M)
1046 if (pagesizes[i] >= G)
1047 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
1048 else if (pagesizes[i] >= M)
1049 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
1050 else
1051 snprintf(name, sizeof(name), "%lu", pagesizes[i]);
1052 #undef G
1053 #undef M
1054 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
1055 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
1056 "number of non-transient largepages allocated");
1057 }
1058 }
1059 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
1060
1061 /*
1062 * Remove all shared memory objects that belong to a prison.
1063 */
1064 void
1065 shm_remove_prison(struct prison *pr)
1066 {
1067 struct shm_mapping *shmm, *tshmm;
1068 u_long i;
1069
1070 sx_xlock(&shm_dict_lock);
1071 for (i = 0; i < shm_hash + 1; i++) {
1072 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
1073 if (shmm->sm_shmfd->shm_object->cred &&
1074 shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1075 shm_doremove(shmm);
1076 }
1077 }
1078 sx_xunlock(&shm_dict_lock);
1079 }
1080
1081 /*
1082 * Dictionary management. We maintain an in-kernel dictionary to map
1083 * paths to shmfd objects. We use the FNV hash on the path to store
1084 * the mappings in a hash table.
1085 */
1086 static struct shmfd *
1087 shm_lookup(char *path, Fnv32_t fnv)
1088 {
1089 struct shm_mapping *map;
1090
1091 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1092 if (map->sm_fnv != fnv)
1093 continue;
1094 if (strcmp(map->sm_path, path) == 0)
1095 return (map->sm_shmfd);
1096 }
1097
1098 return (NULL);
1099 }
1100
1101 static void
1102 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1103 {
1104 struct shm_mapping *map;
1105
1106 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1107 map->sm_path = path;
1108 map->sm_fnv = fnv;
1109 map->sm_shmfd = shm_hold(shmfd);
1110 shmfd->shm_path = path;
1111 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1112 }
1113
1114 static int
1115 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1116 {
1117 struct shm_mapping *map;
1118 int error;
1119
1120 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1121 if (map->sm_fnv != fnv)
1122 continue;
1123 if (strcmp(map->sm_path, path) == 0) {
1124 #ifdef MAC
1125 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1126 if (error)
1127 return (error);
1128 #endif
1129 error = shm_access(map->sm_shmfd, ucred,
1130 FREAD | FWRITE);
1131 if (error)
1132 return (error);
1133 shm_doremove(map);
1134 return (0);
1135 }
1136 }
1137
1138 return (ENOENT);
1139 }
1140
1141 static void
1142 shm_doremove(struct shm_mapping *map)
1143 {
1144 map->sm_shmfd->shm_path = NULL;
1145 LIST_REMOVE(map, sm_link);
1146 shm_drop(map->sm_shmfd);
1147 free(map->sm_path, M_SHMFD);
1148 free(map, M_SHMFD);
1149 }
1150
1151 int
1152 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1153 int shmflags, struct filecaps *fcaps, const char *name __unused)
1154 {
1155 struct pwddesc *pdp;
1156 struct shmfd *shmfd;
1157 struct file *fp;
1158 char *path;
1159 void *rl_cookie;
1160 Fnv32_t fnv;
1161 mode_t cmode;
1162 int error, fd, initial_seals;
1163 bool largepage;
1164
1165 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1166 SHM_LARGEPAGE)) != 0)
1167 return (EINVAL);
1168
1169 initial_seals = F_SEAL_SEAL;
1170 if ((shmflags & SHM_ALLOW_SEALING) != 0)
1171 initial_seals &= ~F_SEAL_SEAL;
1172
1173 #ifdef CAPABILITY_MODE
1174 /*
1175 * shm_open(2) is only allowed for anonymous objects.
1176 */
1177 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
1178 return (ECAPMODE);
1179 #endif
1180
1181 AUDIT_ARG_FFLAGS(flags);
1182 AUDIT_ARG_MODE(mode);
1183
1184 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1185 return (EINVAL);
1186
1187 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
1188 return (EINVAL);
1189
1190 largepage = (shmflags & SHM_LARGEPAGE) != 0;
1191 if (largepage && !PMAP_HAS_LARGEPAGES)
1192 return (ENOTTY);
1193
1194 /*
1195 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
1196 * If the decision is made later to allow additional seals, care must be
1197 * taken below to ensure that the seals are properly set if the shmfd
1198 * already existed -- this currently assumes that only F_SEAL_SEAL can
1199 * be set and doesn't take further precautions to ensure the validity of
1200 * the seals being added with respect to current mappings.
1201 */
1202 if ((initial_seals & ~F_SEAL_SEAL) != 0)
1203 return (EINVAL);
1204
1205 pdp = td->td_proc->p_pd;
1206 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1207
1208 /*
1209 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1210 * by POSIX. We allow it to be unset here so that an in-kernel
1211 * interface may be written as a thin layer around shm, optionally not
1212 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
1213 * in sys_shm_open() to keep this implementation compliant.
1214 */
1215 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1216 if (error)
1217 return (error);
1218
1219 /* A SHM_ANON path pointer creates an anonymous object. */
1220 if (userpath == SHM_ANON) {
1221 /* A read-only anonymous object is pointless. */
1222 if ((flags & O_ACCMODE) == O_RDONLY) {
1223 fdclose(td, fp, fd);
1224 fdrop(fp, td);
1225 return (EINVAL);
1226 }
1227 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1228 shmfd->shm_seals = initial_seals;
1229 shmfd->shm_flags = shmflags;
1230 } else {
1231 error = shm_copyin_path(td, userpath, &path);
1232 if (error != 0) {
1233 fdclose(td, fp, fd);
1234 fdrop(fp, td);
1235 return (error);
1236 }
1237
1238 AUDIT_ARG_UPATH1_CANON(path);
1239 fnv = fnv_32_str(path, FNV1_32_INIT);
1240 sx_xlock(&shm_dict_lock);
1241 shmfd = shm_lookup(path, fnv);
1242 if (shmfd == NULL) {
1243 /* Object does not yet exist, create it if requested. */
1244 if (flags & O_CREAT) {
1245 #ifdef MAC
1246 error = mac_posixshm_check_create(td->td_ucred,
1247 path);
1248 if (error == 0) {
1249 #endif
1250 shmfd = shm_alloc(td->td_ucred, cmode,
1251 largepage);
1252 shmfd->shm_seals = initial_seals;
1253 shmfd->shm_flags = shmflags;
1254 shm_insert(path, fnv, shmfd);
1255 #ifdef MAC
1256 }
1257 #endif
1258 } else {
1259 free(path, M_SHMFD);
1260 error = ENOENT;
1261 }
1262 } else {
1263 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
1264 &shmfd->shm_mtx);
1265
1266 /*
1267 * kern_shm_open() likely shouldn't ever error out on
1268 * trying to set a seal that already exists, unlike
1269 * F_ADD_SEALS. This would break terribly as
1270 * shm_open(2) actually sets F_SEAL_SEAL to maintain
1271 * historical behavior where the underlying file could
1272 * not be sealed.
1273 */
1274 initial_seals &= ~shmfd->shm_seals;
1275
1276 /*
1277 * Object already exists, obtain a new
1278 * reference if requested and permitted.
1279 */
1280 free(path, M_SHMFD);
1281
1282 /*
1283 * initial_seals can't set additional seals if we've
1284 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
1285 * then we've already removed that one from
1286 * initial_seals. This is currently redundant as we
1287 * only allow setting F_SEAL_SEAL at creation time, but
1288 * it's cheap to check and decreases the effort required
1289 * to allow additional seals.
1290 */
1291 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1292 initial_seals != 0)
1293 error = EPERM;
1294 else if ((flags & (O_CREAT | O_EXCL)) ==
1295 (O_CREAT | O_EXCL))
1296 error = EEXIST;
1297 else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1298 error = EINVAL;
1299 else {
1300 #ifdef MAC
1301 error = mac_posixshm_check_open(td->td_ucred,
1302 shmfd, FFLAGS(flags & O_ACCMODE));
1303 if (error == 0)
1304 #endif
1305 error = shm_access(shmfd, td->td_ucred,
1306 FFLAGS(flags & O_ACCMODE));
1307 }
1308
1309 /*
1310 * Truncate the file back to zero length if
1311 * O_TRUNC was specified and the object was
1312 * opened with read/write.
1313 */
1314 if (error == 0 &&
1315 (flags & (O_ACCMODE | O_TRUNC)) ==
1316 (O_RDWR | O_TRUNC)) {
1317 VM_OBJECT_WLOCK(shmfd->shm_object);
1318 #ifdef MAC
1319 error = mac_posixshm_check_truncate(
1320 td->td_ucred, fp->f_cred, shmfd);
1321 if (error == 0)
1322 #endif
1323 error = shm_dotruncate_locked(shmfd, 0,
1324 rl_cookie);
1325 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1326 }
1327 if (error == 0) {
1328 /*
1329 * Currently we only allow F_SEAL_SEAL to be
1330 * set initially. As noted above, this would
1331 * need to be reworked should that change.
1332 */
1333 shmfd->shm_seals |= initial_seals;
1334 shm_hold(shmfd);
1335 }
1336 rangelock_unlock(&shmfd->shm_rl, rl_cookie,
1337 &shmfd->shm_mtx);
1338 }
1339 sx_xunlock(&shm_dict_lock);
1340
1341 if (error) {
1342 fdclose(td, fp, fd);
1343 fdrop(fp, td);
1344 return (error);
1345 }
1346 }
1347
1348 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1349
1350 td->td_retval[0] = fd;
1351 fdrop(fp, td);
1352
1353 return (0);
1354 }
1355
1356 /* System calls. */
1357 #ifdef COMPAT_FREEBSD12
1358 int
1359 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1360 {
1361
1362 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1363 uap->mode, NULL));
1364 }
1365 #endif
1366
1367 int
1368 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1369 {
1370 char *path;
1371 Fnv32_t fnv;
1372 int error;
1373
1374 error = shm_copyin_path(td, uap->path, &path);
1375 if (error != 0)
1376 return (error);
1377
1378 AUDIT_ARG_UPATH1_CANON(path);
1379 fnv = fnv_32_str(path, FNV1_32_INIT);
1380 sx_xlock(&shm_dict_lock);
1381 error = shm_remove(path, fnv, td->td_ucred);
1382 sx_xunlock(&shm_dict_lock);
1383 free(path, M_SHMFD);
1384
1385 return (error);
1386 }
1387
1388 int
1389 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1390 {
1391 char *path_from = NULL, *path_to = NULL;
1392 Fnv32_t fnv_from, fnv_to;
1393 struct shmfd *fd_from;
1394 struct shmfd *fd_to;
1395 int error;
1396 int flags;
1397
1398 flags = uap->flags;
1399 AUDIT_ARG_FFLAGS(flags);
1400
1401 /*
1402 * Make sure the user passed only valid flags.
1403 * If you add a new flag, please add a new term here.
1404 */
1405 if ((flags & ~(
1406 SHM_RENAME_NOREPLACE |
1407 SHM_RENAME_EXCHANGE
1408 )) != 0) {
1409 error = EINVAL;
1410 goto out;
1411 }
1412
1413 /*
1414 * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1415 * force the user to choose one or the other.
1416 */
1417 if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1418 (flags & SHM_RENAME_EXCHANGE) != 0) {
1419 error = EINVAL;
1420 goto out;
1421 }
1422
1423 /* Renaming to or from anonymous makes no sense */
1424 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1425 error = EINVAL;
1426 goto out;
1427 }
1428
1429 error = shm_copyin_path(td, uap->path_from, &path_from);
1430 if (error != 0)
1431 goto out;
1432
1433 error = shm_copyin_path(td, uap->path_to, &path_to);
1434 if (error != 0)
1435 goto out;
1436
1437 AUDIT_ARG_UPATH1_CANON(path_from);
1438 AUDIT_ARG_UPATH2_CANON(path_to);
1439
1440 /* Rename with from/to equal is a no-op */
1441 if (strcmp(path_from, path_to) == 0)
1442 goto out;
1443
1444 fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1445 fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1446
1447 sx_xlock(&shm_dict_lock);
1448
1449 fd_from = shm_lookup(path_from, fnv_from);
1450 if (fd_from == NULL) {
1451 error = ENOENT;
1452 goto out_locked;
1453 }
1454
1455 fd_to = shm_lookup(path_to, fnv_to);
1456 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1457 error = EEXIST;
1458 goto out_locked;
1459 }
1460
1461 /*
1462 * Unconditionally prevents shm_remove from invalidating the 'from'
1463 * shm's state.
1464 */
1465 shm_hold(fd_from);
1466 error = shm_remove(path_from, fnv_from, td->td_ucred);
1467
1468 /*
1469 * One of my assumptions failed if ENOENT (e.g. locking didn't
1470 * protect us)
1471 */
1472 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1473 path_from));
1474 if (error != 0) {
1475 shm_drop(fd_from);
1476 goto out_locked;
1477 }
1478
1479 /*
1480 * If we are exchanging, we need to ensure the shm_remove below
1481 * doesn't invalidate the dest shm's state.
1482 */
1483 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1484 shm_hold(fd_to);
1485
1486 /*
1487 * NOTE: if path_to is not already in the hash, c'est la vie;
1488 * it simply means we have nothing already at path_to to unlink.
1489 * That is the ENOENT case.
1490 *
1491 * If we somehow don't have access to unlink this guy, but
1492 * did for the shm at path_from, then relink the shm to path_from
1493 * and abort with EACCES.
1494 *
1495 * All other errors: that is weird; let's relink and abort the
1496 * operation.
1497 */
1498 error = shm_remove(path_to, fnv_to, td->td_ucred);
1499 if (error != 0 && error != ENOENT) {
1500 shm_insert(path_from, fnv_from, fd_from);
1501 shm_drop(fd_from);
1502 /* Don't free path_from now, since the hash references it */
1503 path_from = NULL;
1504 goto out_locked;
1505 }
1506
1507 error = 0;
1508
1509 shm_insert(path_to, fnv_to, fd_from);
1510
1511 /* Don't free path_to now, since the hash references it */
1512 path_to = NULL;
1513
1514 /* We kept a ref when we removed, and incremented again in insert */
1515 shm_drop(fd_from);
1516 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1517 fd_from->shm_refs));
1518
1519 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1520 shm_insert(path_from, fnv_from, fd_to);
1521 path_from = NULL;
1522 shm_drop(fd_to);
1523 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1524 fd_to->shm_refs));
1525 }
1526
1527 out_locked:
1528 sx_xunlock(&shm_dict_lock);
1529
1530 out:
1531 free(path_from, M_SHMFD);
1532 free(path_to, M_SHMFD);
1533 return (error);
1534 }
1535
1536 static int
1537 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1538 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1539 vm_ooffset_t foff, struct thread *td)
1540 {
1541 struct vmspace *vms;
1542 vm_map_entry_t next_entry, prev_entry;
1543 vm_offset_t align, mask, maxaddr;
1544 int docow, error, rv, try;
1545 bool curmap;
1546
1547 if (shmfd->shm_lp_psind == 0)
1548 return (EINVAL);
1549
1550 /* MAP_PRIVATE is disabled */
1551 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1552 MAP_NOCORE |
1553 #ifdef MAP_32BIT
1554 MAP_32BIT |
1555 #endif
1556 MAP_ALIGNMENT_MASK)) != 0)
1557 return (EINVAL);
1558
1559 vms = td->td_proc->p_vmspace;
1560 curmap = map == &vms->vm_map;
1561 if (curmap) {
1562 error = kern_mmap_racct_check(td, map, size);
1563 if (error != 0)
1564 return (error);
1565 }
1566
1567 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1568 docow |= MAP_INHERIT_SHARE;
1569 if ((flags & MAP_NOCORE) != 0)
1570 docow |= MAP_DISABLE_COREDUMP;
1571
1572 mask = pagesizes[shmfd->shm_lp_psind] - 1;
1573 if ((foff & mask) != 0)
1574 return (EINVAL);
1575 maxaddr = vm_map_max(map);
1576 #ifdef MAP_32BIT
1577 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1578 maxaddr = MAP_32BIT_MAX_ADDR;
1579 #endif
1580 if (size == 0 || (size & mask) != 0 ||
1581 (*addr != 0 && ((*addr & mask) != 0 ||
1582 *addr + size < *addr || *addr + size > maxaddr)))
1583 return (EINVAL);
1584
1585 align = flags & MAP_ALIGNMENT_MASK;
1586 if (align == 0) {
1587 align = pagesizes[shmfd->shm_lp_psind];
1588 } else if (align == MAP_ALIGNED_SUPER) {
1589 if (shmfd->shm_lp_psind != 1)
1590 return (EINVAL);
1591 align = pagesizes[1];
1592 } else {
1593 align >>= MAP_ALIGNMENT_SHIFT;
1594 align = 1ULL << align;
1595 /* Also handles overflow. */
1596 if (align < pagesizes[shmfd->shm_lp_psind])
1597 return (EINVAL);
1598 }
1599
1600 vm_map_lock(map);
1601 if ((flags & MAP_FIXED) == 0) {
1602 try = 1;
1603 if (curmap && (*addr == 0 ||
1604 (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1605 *addr < round_page((vm_offset_t)vms->vm_daddr +
1606 lim_max(td, RLIMIT_DATA))))) {
1607 *addr = roundup2((vm_offset_t)vms->vm_daddr +
1608 lim_max(td, RLIMIT_DATA),
1609 pagesizes[shmfd->shm_lp_psind]);
1610 }
1611 again:
1612 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1613 if (rv != KERN_SUCCESS) {
1614 if (try == 1) {
1615 try = 2;
1616 *addr = vm_map_min(map);
1617 if ((*addr & mask) != 0)
1618 *addr = (*addr + mask) & mask;
1619 goto again;
1620 }
1621 goto fail1;
1622 }
1623 } else if ((flags & MAP_EXCL) == 0) {
1624 rv = vm_map_delete(map, *addr, *addr + size);
1625 if (rv != KERN_SUCCESS)
1626 goto fail1;
1627 } else {
1628 error = ENOSPC;
1629 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1630 goto fail;
1631 next_entry = vm_map_entry_succ(prev_entry);
1632 if (next_entry->start < *addr + size)
1633 goto fail;
1634 }
1635
1636 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1637 prot, max_prot, docow);
1638 fail1:
1639 error = vm_mmap_to_errno(rv);
1640 fail:
1641 vm_map_unlock(map);
1642 return (error);
1643 }
1644
1645 static int
1646 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1647 vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
1648 vm_ooffset_t foff, struct thread *td)
1649 {
1650 struct shmfd *shmfd;
1651 vm_prot_t maxprot;
1652 int error;
1653 bool writecnt;
1654 void *rl_cookie;
1655
1656 shmfd = fp->f_data;
1657 maxprot = VM_PROT_NONE;
1658
1659 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize,
1660 &shmfd->shm_mtx);
1661 /* FREAD should always be set. */
1662 if ((fp->f_flag & FREAD) != 0)
1663 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1664
1665 /*
1666 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1667 * mapping with a write seal applied. Private mappings are always
1668 * writeable.
1669 */
1670 if ((flags & MAP_SHARED) == 0) {
1671 cap_maxprot |= VM_PROT_WRITE;
1672 maxprot |= VM_PROT_WRITE;
1673 writecnt = false;
1674 } else {
1675 if ((fp->f_flag & FWRITE) != 0 &&
1676 (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1677 maxprot |= VM_PROT_WRITE;
1678
1679 /*
1680 * Any mappings from a writable descriptor may be upgraded to
1681 * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1682 * applied between the open and subsequent mmap(2). We want to
1683 * reject application of a write seal as long as any such
1684 * mapping exists so that the seal cannot be trivially bypassed.
1685 */
1686 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1687 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1688 error = EACCES;
1689 goto out;
1690 }
1691 }
1692 maxprot &= cap_maxprot;
1693
1694 /* See comment in vn_mmap(). */
1695 if (
1696 #ifdef _LP64
1697 objsize > OFF_MAX ||
1698 #endif
1699 foff > OFF_MAX - objsize) {
1700 error = EINVAL;
1701 goto out;
1702 }
1703
1704 #ifdef MAC
1705 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1706 if (error != 0)
1707 goto out;
1708 #endif
1709
1710 mtx_lock(&shm_timestamp_lock);
1711 vfs_timestamp(&shmfd->shm_atime);
1712 mtx_unlock(&shm_timestamp_lock);
1713 vm_object_reference(shmfd->shm_object);
1714
1715 if (shm_largepage(shmfd)) {
1716 writecnt = false;
1717 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1718 maxprot, flags, foff, td);
1719 } else {
1720 if (writecnt) {
1721 vm_pager_update_writecount(shmfd->shm_object, 0,
1722 objsize);
1723 }
1724 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1725 shmfd->shm_object, foff, writecnt, td);
1726 }
1727 if (error != 0) {
1728 if (writecnt)
1729 vm_pager_release_writecount(shmfd->shm_object, 0,
1730 objsize);
1731 vm_object_deallocate(shmfd->shm_object);
1732 }
1733 out:
1734 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
1735 return (error);
1736 }
1737
1738 static int
1739 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1740 struct thread *td)
1741 {
1742 struct shmfd *shmfd;
1743 int error;
1744
1745 error = 0;
1746 shmfd = fp->f_data;
1747 mtx_lock(&shm_timestamp_lock);
1748 /*
1749 * SUSv4 says that x bits of permission need not be affected.
1750 * Be consistent with our shm_open there.
1751 */
1752 #ifdef MAC
1753 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1754 if (error != 0)
1755 goto out;
1756 #endif
1757 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1758 VADMIN, active_cred);
1759 if (error != 0)
1760 goto out;
1761 shmfd->shm_mode = mode & ACCESSPERMS;
1762 out:
1763 mtx_unlock(&shm_timestamp_lock);
1764 return (error);
1765 }
1766
1767 static int
1768 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1769 struct thread *td)
1770 {
1771 struct shmfd *shmfd;
1772 int error;
1773
1774 error = 0;
1775 shmfd = fp->f_data;
1776 mtx_lock(&shm_timestamp_lock);
1777 #ifdef MAC
1778 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1779 if (error != 0)
1780 goto out;
1781 #endif
1782 if (uid == (uid_t)-1)
1783 uid = shmfd->shm_uid;
1784 if (gid == (gid_t)-1)
1785 gid = shmfd->shm_gid;
1786 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1787 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1788 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1789 goto out;
1790 shmfd->shm_uid = uid;
1791 shmfd->shm_gid = gid;
1792 out:
1793 mtx_unlock(&shm_timestamp_lock);
1794 return (error);
1795 }
1796
1797 /*
1798 * Helper routines to allow the backing object of a shared memory file
1799 * descriptor to be mapped in the kernel.
1800 */
1801 int
1802 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1803 {
1804 struct shmfd *shmfd;
1805 vm_offset_t kva, ofs;
1806 vm_object_t obj;
1807 int rv;
1808
1809 if (fp->f_type != DTYPE_SHM)
1810 return (EINVAL);
1811 shmfd = fp->f_data;
1812 obj = shmfd->shm_object;
1813 VM_OBJECT_WLOCK(obj);
1814 /*
1815 * XXXRW: This validation is probably insufficient, and subject to
1816 * sign errors. It should be fixed.
1817 */
1818 if (offset >= shmfd->shm_size ||
1819 offset + size > round_page(shmfd->shm_size)) {
1820 VM_OBJECT_WUNLOCK(obj);
1821 return (EINVAL);
1822 }
1823
1824 shmfd->shm_kmappings++;
1825 vm_object_reference_locked(obj);
1826 VM_OBJECT_WUNLOCK(obj);
1827
1828 /* Map the object into the kernel_map and wire it. */
1829 kva = vm_map_min(kernel_map);
1830 ofs = offset & PAGE_MASK;
1831 offset = trunc_page(offset);
1832 size = round_page(size + ofs);
1833 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1834 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1835 VM_PROT_READ | VM_PROT_WRITE, 0);
1836 if (rv == KERN_SUCCESS) {
1837 rv = vm_map_wire(kernel_map, kva, kva + size,
1838 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1839 if (rv == KERN_SUCCESS) {
1840 *memp = (void *)(kva + ofs);
1841 return (0);
1842 }
1843 vm_map_remove(kernel_map, kva, kva + size);
1844 } else
1845 vm_object_deallocate(obj);
1846
1847 /* On failure, drop our mapping reference. */
1848 VM_OBJECT_WLOCK(obj);
1849 shmfd->shm_kmappings--;
1850 VM_OBJECT_WUNLOCK(obj);
1851
1852 return (vm_mmap_to_errno(rv));
1853 }
1854
1855 /*
1856 * We require the caller to unmap the entire entry. This allows us to
1857 * safely decrement shm_kmappings when a mapping is removed.
1858 */
1859 int
1860 shm_unmap(struct file *fp, void *mem, size_t size)
1861 {
1862 struct shmfd *shmfd;
1863 vm_map_entry_t entry;
1864 vm_offset_t kva, ofs;
1865 vm_object_t obj;
1866 vm_pindex_t pindex;
1867 vm_prot_t prot;
1868 boolean_t wired;
1869 vm_map_t map;
1870 int rv;
1871
1872 if (fp->f_type != DTYPE_SHM)
1873 return (EINVAL);
1874 shmfd = fp->f_data;
1875 kva = (vm_offset_t)mem;
1876 ofs = kva & PAGE_MASK;
1877 kva = trunc_page(kva);
1878 size = round_page(size + ofs);
1879 map = kernel_map;
1880 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1881 &obj, &pindex, &prot, &wired);
1882 if (rv != KERN_SUCCESS)
1883 return (EINVAL);
1884 if (entry->start != kva || entry->end != kva + size) {
1885 vm_map_lookup_done(map, entry);
1886 return (EINVAL);
1887 }
1888 vm_map_lookup_done(map, entry);
1889 if (obj != shmfd->shm_object)
1890 return (EINVAL);
1891 vm_map_remove(map, kva, kva + size);
1892 VM_OBJECT_WLOCK(obj);
1893 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1894 shmfd->shm_kmappings--;
1895 VM_OBJECT_WUNLOCK(obj);
1896 return (0);
1897 }
1898
1899 static int
1900 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1901 {
1902 const char *path, *pr_path;
1903 size_t pr_pathlen;
1904 bool visible;
1905
1906 sx_assert(&shm_dict_lock, SA_LOCKED);
1907 kif->kf_type = KF_TYPE_SHM;
1908 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1909 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1910 if (shmfd->shm_path != NULL) {
1911 if (shmfd->shm_path != NULL) {
1912 path = shmfd->shm_path;
1913 pr_path = curthread->td_ucred->cr_prison->pr_path;
1914 if (strcmp(pr_path, "/") != 0) {
1915 /* Return the jail-rooted pathname. */
1916 pr_pathlen = strlen(pr_path);
1917 visible = strncmp(path, pr_path, pr_pathlen)
1918 == 0 && path[pr_pathlen] == '/';
1919 if (list && !visible)
1920 return (EPERM);
1921 if (visible)
1922 path += pr_pathlen;
1923 }
1924 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1925 }
1926 }
1927 return (0);
1928 }
1929
1930 static int
1931 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1932 struct filedesc *fdp __unused)
1933 {
1934 int res;
1935
1936 sx_slock(&shm_dict_lock);
1937 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1938 sx_sunlock(&shm_dict_lock);
1939 return (res);
1940 }
1941
1942 static int
1943 shm_add_seals(struct file *fp, int seals)
1944 {
1945 struct shmfd *shmfd;
1946 void *rl_cookie;
1947 vm_ooffset_t writemappings;
1948 int error, nseals;
1949
1950 error = 0;
1951 shmfd = fp->f_data;
1952 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
1953 &shmfd->shm_mtx);
1954
1955 /* Even already-set seals should result in EPERM. */
1956 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
1957 error = EPERM;
1958 goto out;
1959 }
1960 nseals = seals & ~shmfd->shm_seals;
1961 if ((nseals & F_SEAL_WRITE) != 0) {
1962 if (shm_largepage(shmfd)) {
1963 error = ENOTSUP;
1964 goto out;
1965 }
1966
1967 /*
1968 * The rangelock above prevents writable mappings from being
1969 * added after we've started applying seals. The RLOCK here
1970 * is to avoid torn reads on ILP32 arches as unmapping/reducing
1971 * writemappings will be done without a rangelock.
1972 */
1973 VM_OBJECT_RLOCK(shmfd->shm_object);
1974 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
1975 VM_OBJECT_RUNLOCK(shmfd->shm_object);
1976 /* kmappings are also writable */
1977 if (writemappings > 0) {
1978 error = EBUSY;
1979 goto out;
1980 }
1981 }
1982 shmfd->shm_seals |= nseals;
1983 out:
1984 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
1985 return (error);
1986 }
1987
1988 static int
1989 shm_get_seals(struct file *fp, int *seals)
1990 {
1991 struct shmfd *shmfd;
1992
1993 shmfd = fp->f_data;
1994 *seals = shmfd->shm_seals;
1995 return (0);
1996 }
1997
1998 static int
1999 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
2000 {
2001 vm_object_t object;
2002 vm_pindex_t pistart, pi, piend;
2003 vm_ooffset_t off, len;
2004 int startofs, endofs, end;
2005 int error;
2006
2007 off = *offset;
2008 len = *length;
2009 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
2010 if (off + len > shmfd->shm_size)
2011 len = shmfd->shm_size - off;
2012 object = shmfd->shm_object;
2013 startofs = off & PAGE_MASK;
2014 endofs = (off + len) & PAGE_MASK;
2015 pistart = OFF_TO_IDX(off);
2016 piend = OFF_TO_IDX(off + len);
2017 pi = OFF_TO_IDX(off + PAGE_MASK);
2018 error = 0;
2019
2020 /* Handle the case when offset is on or beyond shm size. */
2021 if ((off_t)len <= 0) {
2022 *length = 0;
2023 return (0);
2024 }
2025
2026 VM_OBJECT_WLOCK(object);
2027
2028 if (startofs != 0) {
2029 end = pistart != piend ? PAGE_SIZE : endofs;
2030 error = shm_partial_page_invalidate(object, pistart, startofs,
2031 end);
2032 if (error)
2033 goto out;
2034 off += end - startofs;
2035 len -= end - startofs;
2036 }
2037
2038 if (pi < piend) {
2039 vm_object_page_remove(object, pi, piend, 0);
2040 off += IDX_TO_OFF(piend - pi);
2041 len -= IDX_TO_OFF(piend - pi);
2042 }
2043
2044 if (endofs != 0 && pistart != piend) {
2045 error = shm_partial_page_invalidate(object, piend, 0, endofs);
2046 if (error)
2047 goto out;
2048 off += endofs;
2049 len -= endofs;
2050 }
2051
2052 out:
2053 VM_OBJECT_WUNLOCK(shmfd->shm_object);
2054 *offset = off;
2055 *length = len;
2056 return (error);
2057 }
2058
2059 static int
2060 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
2061 struct ucred *active_cred, struct thread *td)
2062 {
2063 void *rl_cookie;
2064 struct shmfd *shmfd;
2065 off_t off, len;
2066 int error;
2067
2068 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
2069 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
2070 ("shm_fspacectl: non-zero flags"));
2071 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
2072 ("shm_fspacectl: offset/length overflow or underflow"));
2073 error = EINVAL;
2074 shmfd = fp->f_data;
2075 off = *offset;
2076 len = *length;
2077
2078 rl_cookie = rangelock_wlock(&shmfd->shm_rl, off, off + len,
2079 &shmfd->shm_mtx);
2080 switch (cmd) {
2081 case SPACECTL_DEALLOC:
2082 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2083 error = EPERM;
2084 break;
2085 }
2086 error = shm_deallocate(shmfd, &off, &len, flags);
2087 *offset = off;
2088 *length = len;
2089 break;
2090 default:
2091 __assert_unreachable();
2092 }
2093 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
2094 return (error);
2095 }
2096
2097
2098 static int
2099 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2100 {
2101 void *rl_cookie;
2102 struct shmfd *shmfd;
2103 size_t size;
2104 int error;
2105
2106 /* This assumes that the caller already checked for overflow. */
2107 error = 0;
2108 shmfd = fp->f_data;
2109 size = offset + len;
2110
2111 /*
2112 * Just grab the rangelock for the range that we may be attempting to
2113 * grow, rather than blocking read/write for regions we won't be
2114 * touching while this (potential) resize is in progress. Other
2115 * attempts to resize the shmfd will have to take a write lock from 0 to
2116 * OFF_MAX, so this being potentially beyond the current usable range of
2117 * the shmfd is not necessarily a concern. If other mechanisms are
2118 * added to grow a shmfd, this may need to be re-evaluated.
2119 */
2120 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size,
2121 &shmfd->shm_mtx);
2122 if (size > shmfd->shm_size)
2123 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2124 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
2125 /* Translate to posix_fallocate(2) return value as needed. */
2126 if (error == ENOMEM)
2127 error = ENOSPC;
2128 return (error);
2129 }
2130
2131 static int
2132 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2133 {
2134 struct shm_mapping *shmm;
2135 struct sbuf sb;
2136 struct kinfo_file kif;
2137 u_long i;
2138 int error, error2;
2139
2140 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2141 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2142 error = 0;
2143 sx_slock(&shm_dict_lock);
2144 for (i = 0; i < shm_hash + 1; i++) {
2145 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2146 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2147 &kif, true);
2148 if (error == EPERM) {
2149 error = 0;
2150 continue;
2151 }
2152 if (error != 0)
2153 break;
2154 pack_kinfo(&kif);
2155 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2156 0 : ENOMEM;
2157 if (error != 0)
2158 break;
2159 }
2160 }
2161 sx_sunlock(&shm_dict_lock);
2162 error2 = sbuf_finish(&sb);
2163 sbuf_delete(&sb);
2164 return (error != 0 ? error : error2);
2165 }
2166
2167 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2168 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2169 NULL, 0, sysctl_posix_shm_list, "",
2170 "POSIX SHM list");
2171
2172 int
2173 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2174 struct filecaps *caps)
2175 {
2176
2177 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
2178 }
2179
2180 /*
2181 * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2182 * caller, and libc will enforce it for the traditional shm_open() call. This
2183 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
2184 * interface also includes a 'name' argument that is currently unused, but could
2185 * potentially be exported later via some interface for debugging purposes.
2186 * From the kernel's perspective, it is optional. Individual consumers like
2187 * memfd_create() may require it in order to be compatible with other systems
2188 * implementing the same function.
2189 */
2190 int
2191 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2192 {
2193
2194 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2195 uap->shmflags, NULL, uap->name));
2196 }
Cache object: f10dba62a5e552dfa3ce48a884ec264f
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