1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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 #include "opt_capsicum.h"
52 #include "opt_ktrace.h"
53
54 #include <sys/param.h>
55 #include <sys/capsicum.h>
56 #include <sys/conf.h>
57 #include <sys/fcntl.h>
58 #include <sys/file.h>
59 #include <sys/filedesc.h>
60 #include <sys/filio.h>
61 #include <sys/fnv_hash.h>
62 #include <sys/kernel.h>
63 #include <sys/limits.h>
64 #include <sys/uio.h>
65 #include <sys/signal.h>
66 #include <sys/jail.h>
67 #include <sys/ktrace.h>
68 #include <sys/lock.h>
69 #include <sys/malloc.h>
70 #include <sys/mman.h>
71 #include <sys/mutex.h>
72 #include <sys/priv.h>
73 #include <sys/proc.h>
74 #include <sys/refcount.h>
75 #include <sys/resourcevar.h>
76 #include <sys/rwlock.h>
77 #include <sys/sbuf.h>
78 #include <sys/stat.h>
79 #include <sys/syscallsubr.h>
80 #include <sys/sysctl.h>
81 #include <sys/sysproto.h>
82 #include <sys/systm.h>
83 #include <sys/sx.h>
84 #include <sys/time.h>
85 #include <sys/vmmeter.h>
86 #include <sys/vnode.h>
87 #include <sys/unistd.h>
88 #include <sys/user.h>
89
90 #include <security/audit/audit.h>
91 #include <security/mac/mac_framework.h>
92
93 #include <vm/vm.h>
94 #include <vm/vm_param.h>
95 #include <vm/pmap.h>
96 #include <vm/vm_extern.h>
97 #include <vm/vm_map.h>
98 #include <vm/vm_kern.h>
99 #include <vm/vm_object.h>
100 #include <vm/vm_page.h>
101 #include <vm/vm_pageout.h>
102 #include <vm/vm_pager.h>
103 #include <vm/vm_radix.h>
104 #include <vm/swap_pager.h>
105
106 struct shm_mapping {
107 char *sm_path;
108 Fnv32_t sm_fnv;
109 struct shmfd *sm_shmfd;
110 LIST_ENTRY(shm_mapping) sm_link;
111 };
112
113 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
114 static LIST_HEAD(, shm_mapping) *shm_dictionary;
115 static struct sx shm_dict_lock;
116 static struct mtx shm_timestamp_lock;
117 static u_long shm_hash;
118 static struct unrhdr64 shm_ino_unr;
119 static dev_t shm_dev_ino;
120
121 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
122
123 static void shm_init(void *arg);
124 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
125 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
126 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
127 static void shm_doremove(struct shm_mapping *map);
128 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length,
129 void *rl_cookie);
130 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
131 void *rl_cookie);
132 static int shm_copyin_path(struct thread *td, const char *userpath_in,
133 char **path_out);
134 static int shm_deallocate(struct shmfd *shmfd, off_t *offset,
135 off_t *length, int flags);
136
137 static fo_rdwr_t shm_read;
138 static fo_rdwr_t shm_write;
139 static fo_truncate_t shm_truncate;
140 static fo_ioctl_t shm_ioctl;
141 static fo_stat_t shm_stat;
142 static fo_close_t shm_close;
143 static fo_chmod_t shm_chmod;
144 static fo_chown_t shm_chown;
145 static fo_seek_t shm_seek;
146 static fo_fill_kinfo_t shm_fill_kinfo;
147 static fo_mmap_t shm_mmap;
148 static fo_get_seals_t shm_get_seals;
149 static fo_add_seals_t shm_add_seals;
150 static fo_fallocate_t shm_fallocate;
151 static fo_fspacectl_t shm_fspacectl;
152
153 /* File descriptor operations. */
154 const struct fileops shm_ops = {
155 .fo_read = shm_read,
156 .fo_write = shm_write,
157 .fo_truncate = shm_truncate,
158 .fo_ioctl = shm_ioctl,
159 .fo_poll = invfo_poll,
160 .fo_kqfilter = invfo_kqfilter,
161 .fo_stat = shm_stat,
162 .fo_close = shm_close,
163 .fo_chmod = shm_chmod,
164 .fo_chown = shm_chown,
165 .fo_sendfile = vn_sendfile,
166 .fo_seek = shm_seek,
167 .fo_fill_kinfo = shm_fill_kinfo,
168 .fo_mmap = shm_mmap,
169 .fo_get_seals = shm_get_seals,
170 .fo_add_seals = shm_add_seals,
171 .fo_fallocate = shm_fallocate,
172 .fo_fspacectl = shm_fspacectl,
173 .fo_cmp = file_kcmp_generic,
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 #define shm_rangelock_unlock(shmfd, cookie) \
188 rangelock_unlock(&(shmfd)->shm_rl, (cookie))
189 #define shm_rangelock_rlock(shmfd, start, end) \
190 rangelock_rlock(&(shmfd)->shm_rl, (start), (end))
191 #define shm_rangelock_tryrlock(shmfd, start, end) \
192 rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end))
193 #define shm_rangelock_wlock(shmfd, start, end) \
194 rangelock_wlock(&(shmfd)->shm_rl, (start), (end))
195
196 static int
uiomove_object_page(vm_object_t obj,size_t len,struct uio * uio)197 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
198 {
199 struct pctrie_iter pages;
200 vm_page_t m;
201 vm_pindex_t idx;
202 size_t tlen;
203 int error, offset, rv;
204
205 idx = OFF_TO_IDX(uio->uio_offset);
206 offset = uio->uio_offset & PAGE_MASK;
207 tlen = MIN(PAGE_SIZE - offset, len);
208
209 rv = vm_page_grab_valid_unlocked(&m, obj, idx,
210 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT);
211 if (rv == VM_PAGER_OK)
212 goto found;
213
214 /*
215 * Read I/O without either a corresponding resident page or swap
216 * page: use zero_region. This is intended to avoid instantiating
217 * pages on read from a sparse region.
218 */
219 vm_page_iter_init(&pages, obj);
220 VM_OBJECT_WLOCK(obj);
221 m = vm_radix_iter_lookup(&pages, idx);
222 if (uio->uio_rw == UIO_READ && m == NULL &&
223 !vm_pager_has_page(obj, idx, NULL, NULL)) {
224 VM_OBJECT_WUNLOCK(obj);
225 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
226 }
227
228 /*
229 * Although the tmpfs vnode lock is held here, it is
230 * nonetheless safe to sleep waiting for a free page. The
231 * pageout daemon does not need to acquire the tmpfs vnode
232 * lock to page out tobj's pages because tobj is a OBJT_SWAP
233 * type object.
234 */
235 rv = vm_page_grab_valid_iter(&m, obj, idx,
236 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY, &pages);
237 if (rv != VM_PAGER_OK) {
238 VM_OBJECT_WUNLOCK(obj);
239 if (bootverbose) {
240 printf("uiomove_object: vm_obj %p idx %jd "
241 "pager error %d\n", obj, idx, rv);
242 }
243 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO);
244 }
245 VM_OBJECT_WUNLOCK(obj);
246
247 found:
248 error = uiomove_fromphys(&m, offset, tlen, uio);
249 if (uio->uio_rw == UIO_WRITE && error == 0)
250 vm_page_set_dirty(m);
251 vm_page_activate(m);
252 vm_page_sunbusy(m);
253
254 return (error);
255 }
256
257 int
uiomove_object(vm_object_t obj,off_t obj_size,struct uio * uio)258 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
259 {
260 ssize_t resid;
261 size_t len;
262 int error;
263
264 error = 0;
265 while ((resid = uio->uio_resid) > 0) {
266 if (obj_size <= uio->uio_offset)
267 break;
268 len = MIN(obj_size - uio->uio_offset, resid);
269 if (len == 0)
270 break;
271 error = uiomove_object_page(obj, len, uio);
272 if (error != 0 || resid == uio->uio_resid)
273 break;
274 }
275 return (error);
276 }
277
278 static u_long count_largepages[MAXPAGESIZES];
279
280 static int
shm_largepage_phys_populate(vm_object_t object,vm_pindex_t pidx,int fault_type,vm_prot_t max_prot,vm_pindex_t * first,vm_pindex_t * last)281 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
282 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
283 {
284 vm_page_t m __diagused;
285 int psind;
286
287 psind = object->un_pager.phys.data_val;
288 if (psind == 0 || pidx >= object->size)
289 return (VM_PAGER_FAIL);
290 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
291
292 /*
293 * We only busy the first page in the superpage run. It is
294 * useless to busy whole run since we only remove full
295 * superpage, and it takes too long to busy e.g. 512 * 512 ==
296 * 262144 pages constituing 1G amd64 superage.
297 */
298 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
299 MPASS(m != NULL);
300
301 *last = *first + atop(pagesizes[psind]) - 1;
302 return (VM_PAGER_OK);
303 }
304
305 static boolean_t
shm_largepage_phys_haspage(vm_object_t object,vm_pindex_t pindex,int * before,int * after)306 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
307 int *before, int *after)
308 {
309 int psind;
310
311 psind = object->un_pager.phys.data_val;
312 if (psind == 0 || pindex >= object->size)
313 return (FALSE);
314 if (before != NULL) {
315 *before = pindex - rounddown2(pindex, pagesizes[psind] /
316 PAGE_SIZE);
317 }
318 if (after != NULL) {
319 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
320 pindex;
321 }
322 return (TRUE);
323 }
324
325 static void
shm_largepage_phys_ctor(vm_object_t object,vm_prot_t prot,vm_ooffset_t foff,struct ucred * cred)326 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
327 vm_ooffset_t foff, struct ucred *cred)
328 {
329 object->flags |= OBJ_PG_DTOR;
330 }
331
332 static void
shm_largepage_phys_dtor(vm_object_t object)333 shm_largepage_phys_dtor(vm_object_t object)
334 {
335 int psind;
336
337 VM_OBJECT_ASSERT_WLOCKED(object);
338
339 psind = object->un_pager.phys.data_val;
340 if (psind != 0) {
341 struct pctrie_iter pages;
342 vm_page_t m;
343 bool removed __diagused;
344
345 vm_page_iter_init(&pages, object);
346 restart:
347 VM_RADIX_FOREACH(m, &pages) {
348 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) {
349 pctrie_iter_reset(&pages);
350 goto restart;
351 }
352 removed = vm_page_iter_remove(&pages, m);
353 KASSERT(!removed, ("%s: page %p not wired", __func__, m));
354 vm_page_unwire(m, PQ_NONE);
355 }
356 atomic_subtract_long(&count_largepages[psind],
357 object->size / (pagesizes[psind] / PAGE_SIZE));
358 } else {
359 KASSERT(object->size == 0,
360 ("largepage phys obj %p not initialized bit size %#jx > 0",
361 object, (uintmax_t)object->size));
362 }
363 }
364
365 static const struct phys_pager_ops shm_largepage_phys_ops = {
366 .phys_pg_populate = shm_largepage_phys_populate,
367 .phys_pg_haspage = shm_largepage_phys_haspage,
368 .phys_pg_ctor = shm_largepage_phys_ctor,
369 .phys_pg_dtor = shm_largepage_phys_dtor,
370 };
371
372 bool
shm_largepage(struct shmfd * shmfd)373 shm_largepage(struct shmfd *shmfd)
374 {
375 return (shmfd->shm_object->type == OBJT_PHYS);
376 }
377
378 static void
shm_pager_freespace(vm_object_t obj,vm_pindex_t start,vm_size_t size)379 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size)
380 {
381 struct shmfd *shm;
382 vm_size_t c;
383
384 swap_pager_freespace(obj, start, size, &c);
385 if (c == 0)
386 return;
387
388 shm = obj->un_pager.swp.swp_priv;
389 if (shm == NULL)
390 return;
391 KASSERT(shm->shm_pages >= c,
392 ("shm %p pages %jd free %jd", shm,
393 (uintmax_t)shm->shm_pages, (uintmax_t)c));
394 shm->shm_pages -= c;
395 }
396
397 static void
shm_page_inserted(vm_object_t obj,vm_page_t m)398 shm_page_inserted(vm_object_t obj, vm_page_t m)
399 {
400 struct shmfd *shm;
401
402 shm = obj->un_pager.swp.swp_priv;
403 if (shm == NULL)
404 return;
405 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL))
406 shm->shm_pages += 1;
407 }
408
409 static void
shm_page_removed(vm_object_t obj,vm_page_t m)410 shm_page_removed(vm_object_t obj, vm_page_t m)
411 {
412 struct shmfd *shm;
413
414 shm = obj->un_pager.swp.swp_priv;
415 if (shm == NULL)
416 return;
417 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) {
418 KASSERT(shm->shm_pages >= 1,
419 ("shm %p pages %jd free 1", shm,
420 (uintmax_t)shm->shm_pages));
421 shm->shm_pages -= 1;
422 }
423 }
424
425 static struct pagerops shm_swap_pager_ops = {
426 .pgo_kvme_type = KVME_TYPE_SWAP,
427 .pgo_freespace = shm_pager_freespace,
428 .pgo_page_inserted = shm_page_inserted,
429 .pgo_page_removed = shm_page_removed,
430 };
431 static int shmfd_pager_type = -1;
432
433 static int
shm_seek(struct file * fp,off_t offset,int whence,struct thread * td)434 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
435 {
436 struct shmfd *shmfd;
437 off_t foffset;
438 int error;
439
440 shmfd = fp->f_data;
441 foffset = foffset_lock(fp, 0);
442 error = 0;
443 switch (whence) {
444 case L_INCR:
445 if (foffset < 0 ||
446 (offset > 0 && foffset > OFF_MAX - offset)) {
447 error = EOVERFLOW;
448 break;
449 }
450 offset += foffset;
451 break;
452 case L_XTND:
453 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
454 error = EOVERFLOW;
455 break;
456 }
457 offset += shmfd->shm_size;
458 break;
459 case L_SET:
460 break;
461 default:
462 error = EINVAL;
463 }
464 if (error == 0) {
465 if (offset < 0 || offset > shmfd->shm_size)
466 error = EINVAL;
467 else
468 td->td_uretoff.tdu_off = offset;
469 }
470 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
471 return (error);
472 }
473
474 static int
shm_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)475 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
476 int flags, struct thread *td)
477 {
478 struct shmfd *shmfd;
479 void *rl_cookie;
480 int error;
481
482 shmfd = fp->f_data;
483 #ifdef MAC
484 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
485 if (error)
486 return (error);
487 #endif
488 foffset_lock_uio(fp, uio, flags);
489 rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset,
490 uio->uio_offset + uio->uio_resid);
491 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
492 shm_rangelock_unlock(shmfd, rl_cookie);
493 foffset_unlock_uio(fp, uio, flags);
494 return (error);
495 }
496
497 static int
shm_write(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)498 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
499 int flags, struct thread *td)
500 {
501 struct shmfd *shmfd;
502 void *rl_cookie;
503 int error;
504 off_t newsize;
505
506 KASSERT((flags & FOF_OFFSET) == 0 || uio->uio_offset >= 0,
507 ("%s: negative offset", __func__));
508
509 shmfd = fp->f_data;
510 #ifdef MAC
511 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
512 if (error)
513 return (error);
514 #endif
515 foffset_lock_uio(fp, uio, flags);
516 if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
517 /*
518 * Overflow is only an error if we're supposed to expand on
519 * write. Otherwise, we'll just truncate the write to the
520 * size of the file, which can only grow up to OFF_MAX.
521 */
522 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
523 foffset_unlock_uio(fp, uio, flags);
524 return (EFBIG);
525 }
526
527 newsize = atomic_load_64(&shmfd->shm_size);
528 } else {
529 newsize = uio->uio_offset + uio->uio_resid;
530 }
531 if ((flags & FOF_OFFSET) == 0)
532 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
533 else
534 rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset,
535 MAX(newsize, uio->uio_offset));
536 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) {
537 error = EINVAL;
538 } else if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
539 error = EPERM;
540 } else {
541 error = 0;
542 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
543 newsize > shmfd->shm_size) {
544 error = shm_dotruncate_cookie(shmfd, newsize,
545 rl_cookie);
546 }
547 if (error == 0)
548 error = uiomove_object(shmfd->shm_object,
549 shmfd->shm_size, uio);
550 }
551 shm_rangelock_unlock(shmfd, rl_cookie);
552 foffset_unlock_uio(fp, uio, flags);
553 return (error);
554 }
555
556 static int
shm_truncate(struct file * fp,off_t length,struct ucred * active_cred,struct thread * td)557 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
558 struct thread *td)
559 {
560 struct shmfd *shmfd;
561 #ifdef MAC
562 int error;
563 #endif
564
565 shmfd = fp->f_data;
566 #ifdef MAC
567 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
568 if (error)
569 return (error);
570 #endif
571 return (shm_dotruncate(shmfd, length));
572 }
573
574 int
shm_ioctl(struct file * fp,u_long com,void * data,struct ucred * active_cred,struct thread * td)575 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
576 struct thread *td)
577 {
578 struct shmfd *shmfd;
579 struct shm_largepage_conf *conf;
580 void *rl_cookie;
581
582 shmfd = fp->f_data;
583 switch (com) {
584 case FIONBIO:
585 case FIOASYNC:
586 /*
587 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
588 * just like it would on an unlinked regular file
589 */
590 return (0);
591 case FIOSSHMLPGCNF:
592 if (!shm_largepage(shmfd))
593 return (ENOTTY);
594 conf = data;
595 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
596 if (shmfd->shm_lp_psind != 0 &&
597 conf->psind != shmfd->shm_lp_psind) {
598 shm_rangelock_unlock(shmfd, rl_cookie);
599 return (EINVAL);
600 }
601 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
602 pagesizes[conf->psind] == 0) {
603 shm_rangelock_unlock(shmfd, rl_cookie);
604 return (EINVAL);
605 }
606 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
607 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
608 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) {
609 shm_rangelock_unlock(shmfd, rl_cookie);
610 return (EINVAL);
611 }
612 shmfd->shm_lp_psind = conf->psind;
613 shmfd->shm_lp_alloc_policy = conf->alloc_policy;
614 shmfd->shm_object->un_pager.phys.data_val = conf->psind;
615 shm_rangelock_unlock(shmfd, rl_cookie);
616 return (0);
617 case FIOGSHMLPGCNF:
618 if (!shm_largepage(shmfd))
619 return (ENOTTY);
620 conf = data;
621 rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX);
622 conf->psind = shmfd->shm_lp_psind;
623 conf->alloc_policy = shmfd->shm_lp_alloc_policy;
624 shm_rangelock_unlock(shmfd, rl_cookie);
625 return (0);
626 default:
627 return (ENOTTY);
628 }
629 }
630
631 static int
shm_stat(struct file * fp,struct stat * sb,struct ucred * active_cred)632 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
633 {
634 struct shmfd *shmfd;
635 #ifdef MAC
636 int error;
637 #endif
638
639 shmfd = fp->f_data;
640
641 #ifdef MAC
642 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
643 if (error)
644 return (error);
645 #endif
646
647 /*
648 * Attempt to return sanish values for fstat() on a memory file
649 * descriptor.
650 */
651 bzero(sb, sizeof(*sb));
652 sb->st_blksize = PAGE_SIZE;
653 sb->st_size = shmfd->shm_size;
654 mtx_lock(&shm_timestamp_lock);
655 sb->st_atim = shmfd->shm_atime;
656 sb->st_ctim = shmfd->shm_ctime;
657 sb->st_mtim = shmfd->shm_mtime;
658 sb->st_birthtim = shmfd->shm_birthtime;
659 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
660 sb->st_uid = shmfd->shm_uid;
661 sb->st_gid = shmfd->shm_gid;
662 mtx_unlock(&shm_timestamp_lock);
663 sb->st_dev = shm_dev_ino;
664 sb->st_ino = shmfd->shm_ino;
665 sb->st_nlink = shmfd->shm_object->ref_count;
666 sb->st_blocks = ptoa(shm_largepage(shmfd) ? shmfd->shm_object->size :
667 shmfd->shm_pages) / DEV_BSIZE;
668
669 return (0);
670 }
671
672 static int
shm_close(struct file * fp,struct thread * td)673 shm_close(struct file *fp, struct thread *td)
674 {
675 struct shmfd *shmfd;
676
677 shmfd = fp->f_data;
678 fp->f_data = NULL;
679 shm_drop(shmfd);
680
681 return (0);
682 }
683
684 static int
shm_copyin_path(struct thread * td,const char * userpath_in,char ** path_out)685 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
686 int error;
687 char *path;
688 const char *pr_path;
689 size_t pr_pathlen;
690
691 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
692 pr_path = td->td_ucred->cr_prison->pr_path;
693
694 /* Construct a full pathname for jailed callers. */
695 pr_pathlen = strcmp(pr_path, "/") ==
696 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
697 error = copyinstr(userpath_in, path + pr_pathlen,
698 MAXPATHLEN - pr_pathlen, NULL);
699 if (error != 0)
700 goto out;
701
702 #ifdef KTRACE
703 if (KTRPOINT(curthread, KTR_NAMEI))
704 ktrnamei(path);
705 #endif
706
707 /* Require paths to start with a '/' character. */
708 if (path[pr_pathlen] != '/') {
709 error = EINVAL;
710 goto out;
711 }
712
713 *path_out = path;
714
715 out:
716 if (error != 0)
717 free(path, M_SHMFD);
718
719 return (error);
720 }
721
722 static int
shm_partial_page_invalidate(vm_object_t object,vm_pindex_t idx,int base,int end)723 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
724 int end)
725 {
726 int error;
727
728 error = vm_page_grab_zero_partial(object, idx, base, end);
729 if (error == EIO)
730 VM_OBJECT_WUNLOCK(object);
731 return (error);
732 }
733
734 static int
shm_dotruncate_locked(struct shmfd * shmfd,off_t length,void * rl_cookie)735 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
736 {
737 vm_object_t object;
738 vm_pindex_t nobjsize;
739 vm_ooffset_t delta;
740 int base, error;
741
742 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
743 object = shmfd->shm_object;
744 VM_OBJECT_ASSERT_WLOCKED(object);
745 rangelock_cookie_assert(rl_cookie, RCA_WLOCKED);
746 if (length == shmfd->shm_size)
747 return (0);
748 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
749
750 /* Are we shrinking? If so, trim the end. */
751 if (length < shmfd->shm_size) {
752 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
753 return (EPERM);
754
755 /*
756 * Disallow any requests to shrink the size if this
757 * object is mapped into the kernel.
758 */
759 if (shmfd->shm_kmappings > 0)
760 return (EBUSY);
761
762 /*
763 * Zero the truncated part of the last page.
764 */
765 base = length & PAGE_MASK;
766 if (base != 0) {
767 error = shm_partial_page_invalidate(object,
768 OFF_TO_IDX(length), base, PAGE_SIZE);
769 if (error)
770 return (error);
771 }
772 delta = IDX_TO_OFF(object->size - nobjsize);
773
774 if (nobjsize < object->size)
775 vm_object_page_remove(object, nobjsize, object->size,
776 0);
777
778 /* Free the swap accounted for shm */
779 swap_release_by_cred(delta, object->cred);
780 } else {
781 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
782 return (EPERM);
783
784 /* Try to reserve additional swap space. */
785 delta = IDX_TO_OFF(nobjsize - object->size);
786 if (!swap_reserve_by_cred(delta, object->cred))
787 return (ENOMEM);
788 }
789 shmfd->shm_size = length;
790 mtx_lock(&shm_timestamp_lock);
791 vfs_timestamp(&shmfd->shm_ctime);
792 shmfd->shm_mtime = shmfd->shm_ctime;
793 mtx_unlock(&shm_timestamp_lock);
794 object->size = nobjsize;
795 return (0);
796 }
797
798 static int
shm_dotruncate_largepage(struct shmfd * shmfd,off_t length,void * rl_cookie)799 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
800 {
801 vm_object_t object;
802 vm_page_t m;
803 vm_pindex_t newobjsz;
804 vm_pindex_t oldobjsz __unused;
805 int aflags, error, i, psind, try;
806
807 KASSERT(length >= 0, ("shm_dotruncate_largepage: length < 0"));
808 object = shmfd->shm_object;
809 VM_OBJECT_ASSERT_WLOCKED(object);
810 rangelock_cookie_assert(rl_cookie, RCA_WLOCKED);
811
812 oldobjsz = object->size;
813 newobjsz = OFF_TO_IDX(length);
814 if (length == shmfd->shm_size)
815 return (0);
816 psind = shmfd->shm_lp_psind;
817 if (psind == 0 && length != 0)
818 return (EINVAL);
819 if ((length & (pagesizes[psind] - 1)) != 0)
820 return (EINVAL);
821
822 if (length < shmfd->shm_size) {
823 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
824 return (EPERM);
825 if (shmfd->shm_kmappings > 0)
826 return (EBUSY);
827 return (ENOTSUP); /* Pages are unmanaged. */
828 #if 0
829 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
830 object->size = newobjsz;
831 shmfd->shm_size = length;
832 return (0);
833 #endif
834 }
835
836 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
837 return (EPERM);
838
839 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO | VM_ALLOC_WIRED;
840 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
841 aflags |= VM_ALLOC_WAITFAIL;
842 try = 0;
843
844 /*
845 * Extend shmfd and object, keeping all already fully
846 * allocated large pages intact even on error, because dropped
847 * object lock might allowed mapping of them.
848 */
849 while (object->size < newobjsz) {
850 error = sig_intr();
851 if (error != 0)
852 return (error);
853 m = vm_page_alloc_contig(object, object->size, aflags,
854 pagesizes[psind] / PAGE_SIZE, 0, ~0,
855 pagesizes[psind], 0,
856 VM_MEMATTR_DEFAULT);
857 if (m == NULL) {
858 VM_OBJECT_WUNLOCK(object);
859 error = sig_intr();
860 if (error != 0) {
861 VM_OBJECT_WLOCK(object);
862 return (error);
863 }
864 if (shmfd->shm_lp_alloc_policy ==
865 SHM_LARGEPAGE_ALLOC_NOWAIT ||
866 (shmfd->shm_lp_alloc_policy ==
867 SHM_LARGEPAGE_ALLOC_DEFAULT &&
868 try >= largepage_reclaim_tries)) {
869 VM_OBJECT_WLOCK(object);
870 return (ENOMEM);
871 }
872 error = vm_page_reclaim_contig(aflags,
873 pagesizes[psind] / PAGE_SIZE, 0, ~0,
874 pagesizes[psind], 0);
875 if (error == ENOMEM)
876 error = vm_wait_intr(object);
877 if (error != 0) {
878 VM_OBJECT_WLOCK(object);
879 return (error);
880 }
881 try++;
882 VM_OBJECT_WLOCK(object);
883 continue;
884 }
885 try = 0;
886 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
887 if ((m[i].flags & PG_ZERO) == 0)
888 pmap_zero_page(&m[i]);
889 vm_page_valid(&m[i]);
890 vm_page_xunbusy(&m[i]);
891 }
892 object->size += OFF_TO_IDX(pagesizes[psind]);
893 shmfd->shm_size += pagesizes[psind];
894 atomic_add_long(&count_largepages[psind], 1);
895 }
896 return (0);
897 }
898
899 static int
shm_dotruncate_cookie(struct shmfd * shmfd,off_t length,void * rl_cookie)900 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
901 {
902 int error;
903
904 VM_OBJECT_WLOCK(shmfd->shm_object);
905 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
906 length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
907 rl_cookie);
908 VM_OBJECT_WUNLOCK(shmfd->shm_object);
909 return (error);
910 }
911
912 int
shm_dotruncate(struct shmfd * shmfd,off_t length)913 shm_dotruncate(struct shmfd *shmfd, off_t length)
914 {
915 void *rl_cookie;
916 int error;
917
918 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
919 error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
920 shm_rangelock_unlock(shmfd, rl_cookie);
921 return (error);
922 }
923
924 /*
925 * shmfd object management including creation and reference counting
926 * routines.
927 */
928 struct shmfd *
shm_alloc(struct ucred * ucred,mode_t mode,bool largepage)929 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
930 {
931 struct shmfd *shmfd;
932 vm_object_t obj;
933
934 if (largepage) {
935 obj = phys_pager_allocate(NULL, &shm_largepage_phys_ops,
936 NULL, 0, VM_PROT_DEFAULT, 0, ucred);
937 } else {
938 obj = vm_pager_allocate(shmfd_pager_type, NULL, 0,
939 VM_PROT_DEFAULT, 0, ucred);
940 }
941 if (obj == NULL) {
942 /*
943 * swap reservation limits can cause object allocation
944 * to fail.
945 */
946 return (NULL);
947 }
948
949 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
950 shmfd->shm_uid = ucred->cr_uid;
951 shmfd->shm_gid = ucred->cr_gid;
952 shmfd->shm_mode = mode;
953 if (largepage) {
954 obj->un_pager.phys.phys_priv = shmfd;
955 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
956 } else {
957 obj->un_pager.swp.swp_priv = shmfd;
958 }
959
960 VM_OBJECT_WLOCK(obj);
961 vm_object_set_flag(obj, OBJ_POSIXSHM);
962 VM_OBJECT_WUNLOCK(obj);
963 shmfd->shm_object = obj;
964 vfs_timestamp(&shmfd->shm_birthtime);
965 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
966 shmfd->shm_birthtime;
967 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
968 refcount_init(&shmfd->shm_refs, 1);
969 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
970 rangelock_init(&shmfd->shm_rl);
971 #ifdef MAC
972 mac_posixshm_init(shmfd);
973 mac_posixshm_create(ucred, shmfd);
974 #endif
975
976 return (shmfd);
977 }
978
979 struct shmfd *
shm_hold(struct shmfd * shmfd)980 shm_hold(struct shmfd *shmfd)
981 {
982
983 refcount_acquire(&shmfd->shm_refs);
984 return (shmfd);
985 }
986
987 void
shm_drop(struct shmfd * shmfd)988 shm_drop(struct shmfd *shmfd)
989 {
990 vm_object_t obj;
991
992 if (refcount_release(&shmfd->shm_refs)) {
993 #ifdef MAC
994 mac_posixshm_destroy(shmfd);
995 #endif
996 rangelock_destroy(&shmfd->shm_rl);
997 mtx_destroy(&shmfd->shm_mtx);
998 obj = shmfd->shm_object;
999 VM_OBJECT_WLOCK(obj);
1000 if (shm_largepage(shmfd))
1001 obj->un_pager.phys.phys_priv = NULL;
1002 else
1003 obj->un_pager.swp.swp_priv = NULL;
1004 VM_OBJECT_WUNLOCK(obj);
1005 vm_object_deallocate(obj);
1006 free(shmfd, M_SHMFD);
1007 }
1008 }
1009
1010 /*
1011 * Determine if the credentials have sufficient permissions for a
1012 * specified combination of FREAD and FWRITE.
1013 */
1014 int
shm_access(struct shmfd * shmfd,struct ucred * ucred,int flags)1015 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
1016 {
1017 accmode_t accmode;
1018 int error;
1019
1020 accmode = 0;
1021 if (flags & FREAD)
1022 accmode |= VREAD;
1023 if (flags & FWRITE)
1024 accmode |= VWRITE;
1025 mtx_lock(&shm_timestamp_lock);
1026 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1027 accmode, ucred);
1028 mtx_unlock(&shm_timestamp_lock);
1029 return (error);
1030 }
1031
1032 static void
shm_init(void * arg)1033 shm_init(void *arg)
1034 {
1035 char name[32];
1036 int i;
1037
1038 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
1039 sx_init(&shm_dict_lock, "shm dictionary");
1040 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
1041 new_unrhdr64(&shm_ino_unr, 1);
1042 shm_dev_ino = devfs_alloc_cdp_inode();
1043 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
1044 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
1045 OBJT_SWAP);
1046 MPASS(shmfd_pager_type != -1);
1047
1048 for (i = 1; i < MAXPAGESIZES; i++) {
1049 if (pagesizes[i] == 0)
1050 break;
1051 #define M (1024 * 1024)
1052 #define G (1024 * M)
1053 if (pagesizes[i] >= G)
1054 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
1055 else if (pagesizes[i] >= M)
1056 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
1057 else
1058 snprintf(name, sizeof(name), "%lu", pagesizes[i]);
1059 #undef G
1060 #undef M
1061 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
1062 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
1063 "number of non-transient largepages allocated");
1064 }
1065 }
1066 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
1067
1068 /*
1069 * Remove all shared memory objects that belong to a prison.
1070 */
1071 void
shm_remove_prison(struct prison * pr)1072 shm_remove_prison(struct prison *pr)
1073 {
1074 struct shm_mapping *shmm, *tshmm;
1075 u_long i;
1076
1077 sx_xlock(&shm_dict_lock);
1078 for (i = 0; i < shm_hash + 1; i++) {
1079 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
1080 if (shmm->sm_shmfd->shm_object->cred &&
1081 shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1082 shm_doremove(shmm);
1083 }
1084 }
1085 sx_xunlock(&shm_dict_lock);
1086 }
1087
1088 /*
1089 * Dictionary management. We maintain an in-kernel dictionary to map
1090 * paths to shmfd objects. We use the FNV hash on the path to store
1091 * the mappings in a hash table.
1092 */
1093 static struct shmfd *
shm_lookup(char * path,Fnv32_t fnv)1094 shm_lookup(char *path, Fnv32_t fnv)
1095 {
1096 struct shm_mapping *map;
1097
1098 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1099 if (map->sm_fnv != fnv)
1100 continue;
1101 if (strcmp(map->sm_path, path) == 0)
1102 return (map->sm_shmfd);
1103 }
1104
1105 return (NULL);
1106 }
1107
1108 static void
shm_insert(char * path,Fnv32_t fnv,struct shmfd * shmfd)1109 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1110 {
1111 struct shm_mapping *map;
1112
1113 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1114 map->sm_path = path;
1115 map->sm_fnv = fnv;
1116 map->sm_shmfd = shm_hold(shmfd);
1117 shmfd->shm_path = path;
1118 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1119 }
1120
1121 static int
shm_remove(char * path,Fnv32_t fnv,struct ucred * ucred)1122 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1123 {
1124 struct shm_mapping *map;
1125 int error;
1126
1127 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1128 if (map->sm_fnv != fnv)
1129 continue;
1130 if (strcmp(map->sm_path, path) == 0) {
1131 #ifdef MAC
1132 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1133 if (error)
1134 return (error);
1135 #endif
1136 error = shm_access(map->sm_shmfd, ucred,
1137 FREAD | FWRITE);
1138 if (error)
1139 return (error);
1140 shm_doremove(map);
1141 return (0);
1142 }
1143 }
1144
1145 return (ENOENT);
1146 }
1147
1148 static void
shm_doremove(struct shm_mapping * map)1149 shm_doremove(struct shm_mapping *map)
1150 {
1151 map->sm_shmfd->shm_path = NULL;
1152 LIST_REMOVE(map, sm_link);
1153 shm_drop(map->sm_shmfd);
1154 free(map->sm_path, M_SHMFD);
1155 free(map, M_SHMFD);
1156 }
1157
1158 int
kern_shm_open2(struct thread * td,const char * userpath,int flags,mode_t mode,int shmflags,struct filecaps * fcaps,const char * name __unused,struct shmfd * shmfd)1159 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1160 int shmflags, struct filecaps *fcaps, const char *name __unused,
1161 struct shmfd *shmfd)
1162 {
1163 struct pwddesc *pdp;
1164 struct file *fp;
1165 char *path;
1166 void *rl_cookie;
1167 Fnv32_t fnv;
1168 mode_t cmode;
1169 int error, fd, initial_seals;
1170 bool largepage;
1171
1172 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1173 SHM_LARGEPAGE)) != 0)
1174 return (EINVAL);
1175
1176 initial_seals = F_SEAL_SEAL;
1177 if ((shmflags & SHM_ALLOW_SEALING) != 0)
1178 initial_seals &= ~F_SEAL_SEAL;
1179
1180 AUDIT_ARG_FFLAGS(flags);
1181 AUDIT_ARG_MODE(mode);
1182
1183 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1184 return (EINVAL);
1185
1186 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC |
1187 O_CLOFORK)) != 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 if (userpath != SHM_ANON) {
1206 error = shm_copyin_path(td, userpath, &path);
1207 if (error != 0)
1208 return (error);
1209
1210 #ifdef CAPABILITY_MODE
1211 /*
1212 * shm_open(2) is only allowed for anonymous objects.
1213 */
1214 if (CAP_TRACING(td))
1215 ktrcapfail(CAPFAIL_NAMEI, path);
1216 if (IN_CAPABILITY_MODE(td)) {
1217 error = ECAPMODE;
1218 goto outnofp;
1219 }
1220 #endif
1221
1222 AUDIT_ARG_UPATH1_CANON(path);
1223 } else {
1224 path = NULL;
1225 }
1226
1227 pdp = td->td_proc->p_pd;
1228 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1229
1230 /*
1231 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1232 * by POSIX. We allow it to be unset here so that an in-kernel
1233 * interface may be written as a thin layer around shm, optionally not
1234 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
1235 * in sys_shm_open() to keep this implementation compliant.
1236 */
1237 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1238 if (error != 0)
1239 goto outnofp;
1240
1241 /*
1242 * A SHM_ANON path pointer creates an anonymous object. We allow other
1243 * parts of the kernel to pre-populate a shmfd and then materialize an
1244 * fd for it here as a means to pass data back up to userland. This
1245 * doesn't really make sense for named shm objects, but it makes plenty
1246 * of sense for anonymous objects.
1247 */
1248 if (userpath == SHM_ANON) {
1249 if (shmfd != NULL) {
1250 shm_hold(shmfd);
1251 } else {
1252 /*
1253 * A read-only anonymous object is pointless, unless it
1254 * was pre-populated by the kernel with the expectation
1255 * that a shmfd would later be created for userland to
1256 * access it through.
1257 */
1258 if ((flags & O_ACCMODE) == O_RDONLY) {
1259 error = EINVAL;
1260 goto out;
1261 }
1262 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1263 if (shmfd == NULL) {
1264 error = ENOMEM;
1265 goto out;
1266 }
1267
1268 shmfd->shm_seals = initial_seals;
1269 shmfd->shm_flags = shmflags;
1270 }
1271 } else {
1272 fnv = fnv_32_str(path, FNV1_32_INIT);
1273 sx_xlock(&shm_dict_lock);
1274
1275 MPASS(shmfd == NULL);
1276 shmfd = shm_lookup(path, fnv);
1277 if (shmfd == NULL) {
1278 /* Object does not yet exist, create it if requested. */
1279 if (flags & O_CREAT) {
1280 #ifdef MAC
1281 error = mac_posixshm_check_create(td->td_ucred,
1282 path);
1283 if (error == 0) {
1284 #endif
1285 shmfd = shm_alloc(td->td_ucred, cmode,
1286 largepage);
1287 if (shmfd == NULL) {
1288 error = ENOMEM;
1289 } else {
1290 shmfd->shm_seals =
1291 initial_seals;
1292 shmfd->shm_flags = shmflags;
1293 shm_insert(path, fnv, shmfd);
1294 path = NULL;
1295 }
1296 #ifdef MAC
1297 }
1298 #endif
1299 } else {
1300 error = ENOENT;
1301 }
1302 } else {
1303 /*
1304 * Object already exists, obtain a new reference if
1305 * requested and permitted.
1306 */
1307 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1308
1309 /*
1310 * kern_shm_open() likely shouldn't ever error out on
1311 * trying to set a seal that already exists, unlike
1312 * F_ADD_SEALS. This would break terribly as
1313 * shm_open(2) actually sets F_SEAL_SEAL to maintain
1314 * historical behavior where the underlying file could
1315 * not be sealed.
1316 */
1317 initial_seals &= ~shmfd->shm_seals;
1318
1319 /*
1320 * initial_seals can't set additional seals if we've
1321 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
1322 * then we've already removed that one from
1323 * initial_seals. This is currently redundant as we
1324 * only allow setting F_SEAL_SEAL at creation time, but
1325 * it's cheap to check and decreases the effort required
1326 * to allow additional seals.
1327 */
1328 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1329 initial_seals != 0)
1330 error = EPERM;
1331 else if ((flags & (O_CREAT | O_EXCL)) ==
1332 (O_CREAT | O_EXCL))
1333 error = EEXIST;
1334 else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1335 error = EINVAL;
1336 else {
1337 #ifdef MAC
1338 error = mac_posixshm_check_open(td->td_ucred,
1339 shmfd, FFLAGS(flags & O_ACCMODE));
1340 if (error == 0)
1341 #endif
1342 error = shm_access(shmfd, td->td_ucred,
1343 FFLAGS(flags & O_ACCMODE));
1344 }
1345
1346 /*
1347 * Truncate the file back to zero length if
1348 * O_TRUNC was specified and the object was
1349 * opened with read/write.
1350 */
1351 if (error == 0 &&
1352 (flags & (O_ACCMODE | O_TRUNC)) ==
1353 (O_RDWR | O_TRUNC)) {
1354 #ifdef MAC
1355 error = mac_posixshm_check_truncate(
1356 td->td_ucred, fp->f_cred, shmfd);
1357 if (error == 0)
1358 #endif
1359 error = shm_dotruncate_cookie(shmfd, 0,
1360 rl_cookie);
1361 }
1362 if (error == 0) {
1363 /*
1364 * Currently we only allow F_SEAL_SEAL to be
1365 * set initially. As noted above, this would
1366 * need to be reworked should that change.
1367 */
1368 shmfd->shm_seals |= initial_seals;
1369 shm_hold(shmfd);
1370 }
1371 shm_rangelock_unlock(shmfd, rl_cookie);
1372 }
1373 sx_xunlock(&shm_dict_lock);
1374
1375 if (error != 0)
1376 goto out;
1377 }
1378
1379 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1380
1381 td->td_retval[0] = fd;
1382 fdrop(fp, td);
1383 free(path, M_SHMFD);
1384
1385 return (0);
1386
1387 out:
1388 fdclose(td, fp, fd);
1389 fdrop(fp, td);
1390 outnofp:
1391 free(path, M_SHMFD);
1392
1393 return (error);
1394 }
1395
1396 /* System calls. */
1397 #ifdef COMPAT_FREEBSD12
1398 int
freebsd12_shm_open(struct thread * td,struct freebsd12_shm_open_args * uap)1399 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1400 {
1401
1402 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1403 uap->mode, NULL));
1404 }
1405 #endif
1406
1407 int
sys_shm_unlink(struct thread * td,struct shm_unlink_args * uap)1408 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1409 {
1410 char *path;
1411 Fnv32_t fnv;
1412 int error;
1413
1414 error = shm_copyin_path(td, uap->path, &path);
1415 if (error != 0)
1416 return (error);
1417
1418 AUDIT_ARG_UPATH1_CANON(path);
1419 fnv = fnv_32_str(path, FNV1_32_INIT);
1420 sx_xlock(&shm_dict_lock);
1421 error = shm_remove(path, fnv, td->td_ucred);
1422 sx_xunlock(&shm_dict_lock);
1423 free(path, M_SHMFD);
1424
1425 return (error);
1426 }
1427
1428 int
sys_shm_rename(struct thread * td,struct shm_rename_args * uap)1429 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1430 {
1431 char *path_from = NULL, *path_to = NULL;
1432 Fnv32_t fnv_from, fnv_to;
1433 struct shmfd *fd_from;
1434 struct shmfd *fd_to;
1435 int error;
1436 int flags;
1437
1438 flags = uap->flags;
1439 AUDIT_ARG_FFLAGS(flags);
1440
1441 /*
1442 * Make sure the user passed only valid flags.
1443 * If you add a new flag, please add a new term here.
1444 */
1445 if ((flags & ~(
1446 SHM_RENAME_NOREPLACE |
1447 SHM_RENAME_EXCHANGE
1448 )) != 0) {
1449 error = EINVAL;
1450 goto out;
1451 }
1452
1453 /*
1454 * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1455 * force the user to choose one or the other.
1456 */
1457 if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1458 (flags & SHM_RENAME_EXCHANGE) != 0) {
1459 error = EINVAL;
1460 goto out;
1461 }
1462
1463 /* Renaming to or from anonymous makes no sense */
1464 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1465 error = EINVAL;
1466 goto out;
1467 }
1468
1469 error = shm_copyin_path(td, uap->path_from, &path_from);
1470 if (error != 0)
1471 goto out;
1472
1473 error = shm_copyin_path(td, uap->path_to, &path_to);
1474 if (error != 0)
1475 goto out;
1476
1477 AUDIT_ARG_UPATH1_CANON(path_from);
1478 AUDIT_ARG_UPATH2_CANON(path_to);
1479
1480 /* Rename with from/to equal is a no-op */
1481 if (strcmp(path_from, path_to) == 0)
1482 goto out;
1483
1484 fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1485 fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1486
1487 sx_xlock(&shm_dict_lock);
1488
1489 fd_from = shm_lookup(path_from, fnv_from);
1490 if (fd_from == NULL) {
1491 error = ENOENT;
1492 goto out_locked;
1493 }
1494
1495 fd_to = shm_lookup(path_to, fnv_to);
1496 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1497 error = EEXIST;
1498 goto out_locked;
1499 }
1500
1501 /*
1502 * Unconditionally prevents shm_remove from invalidating the 'from'
1503 * shm's state.
1504 */
1505 shm_hold(fd_from);
1506 error = shm_remove(path_from, fnv_from, td->td_ucred);
1507
1508 /*
1509 * One of my assumptions failed if ENOENT (e.g. locking didn't
1510 * protect us)
1511 */
1512 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1513 path_from));
1514 if (error != 0) {
1515 shm_drop(fd_from);
1516 goto out_locked;
1517 }
1518
1519 /*
1520 * If we are exchanging, we need to ensure the shm_remove below
1521 * doesn't invalidate the dest shm's state.
1522 */
1523 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1524 shm_hold(fd_to);
1525
1526 /*
1527 * NOTE: if path_to is not already in the hash, c'est la vie;
1528 * it simply means we have nothing already at path_to to unlink.
1529 * That is the ENOENT case.
1530 *
1531 * If we somehow don't have access to unlink this guy, but
1532 * did for the shm at path_from, then relink the shm to path_from
1533 * and abort with EACCES.
1534 *
1535 * All other errors: that is weird; let's relink and abort the
1536 * operation.
1537 */
1538 error = shm_remove(path_to, fnv_to, td->td_ucred);
1539 if (error != 0 && error != ENOENT) {
1540 shm_insert(path_from, fnv_from, fd_from);
1541 shm_drop(fd_from);
1542 /* Don't free path_from now, since the hash references it */
1543 path_from = NULL;
1544 goto out_locked;
1545 }
1546
1547 error = 0;
1548
1549 shm_insert(path_to, fnv_to, fd_from);
1550
1551 /* Don't free path_to now, since the hash references it */
1552 path_to = NULL;
1553
1554 /* We kept a ref when we removed, and incremented again in insert */
1555 shm_drop(fd_from);
1556 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1557 fd_from->shm_refs));
1558
1559 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1560 shm_insert(path_from, fnv_from, fd_to);
1561 path_from = NULL;
1562 shm_drop(fd_to);
1563 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1564 fd_to->shm_refs));
1565 }
1566
1567 out_locked:
1568 sx_xunlock(&shm_dict_lock);
1569
1570 out:
1571 free(path_from, M_SHMFD);
1572 free(path_to, M_SHMFD);
1573 return (error);
1574 }
1575
1576 static int
shm_mmap_large(struct shmfd * shmfd,vm_map_t map,vm_offset_t * addr,vm_size_t size,vm_prot_t prot,vm_prot_t max_prot,int flags,vm_ooffset_t foff,struct thread * td,void * rl_cookie)1577 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1578 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1579 vm_ooffset_t foff, struct thread *td, void *rl_cookie)
1580 {
1581 struct vmspace *vms;
1582 vm_map_entry_t next_entry, prev_entry;
1583 vm_offset_t align, mask, maxaddr;
1584 int docow, error, rv, try;
1585 bool curmap;
1586
1587 rangelock_cookie_assert(rl_cookie, RCA_LOCKED);
1588
1589 if (shmfd->shm_lp_psind == 0)
1590 return (EINVAL);
1591
1592 /* MAP_PRIVATE is disabled */
1593 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1594 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0)
1595 return (EINVAL);
1596
1597 vms = td->td_proc->p_vmspace;
1598 curmap = map == &vms->vm_map;
1599 if (curmap) {
1600 error = kern_mmap_racct_check(td, map, size);
1601 if (error != 0)
1602 return (error);
1603 }
1604
1605 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1606 docow |= MAP_INHERIT_SHARE;
1607 if ((flags & MAP_NOCORE) != 0)
1608 docow |= MAP_DISABLE_COREDUMP;
1609
1610 mask = pagesizes[shmfd->shm_lp_psind] - 1;
1611 if ((foff & mask) != 0)
1612 return (EINVAL);
1613 maxaddr = vm_map_max(map);
1614 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1615 maxaddr = MAP_32BIT_MAX_ADDR;
1616 if (size == 0 || (size & mask) != 0 ||
1617 (*addr != 0 && ((*addr & mask) != 0 ||
1618 *addr + size < *addr || *addr + size > maxaddr)))
1619 return (EINVAL);
1620
1621 align = flags & MAP_ALIGNMENT_MASK;
1622 if (align == 0) {
1623 align = pagesizes[shmfd->shm_lp_psind];
1624 } else if (align == MAP_ALIGNED_SUPER) {
1625 /*
1626 * MAP_ALIGNED_SUPER is only supported on superpage sizes,
1627 * i.e., [1, VM_NRESERVLEVEL]. shmfd->shm_lp_psind < 1 is
1628 * handled above.
1629 */
1630 if (
1631 #if VM_NRESERVLEVEL > 0
1632 shmfd->shm_lp_psind > VM_NRESERVLEVEL
1633 #else
1634 shmfd->shm_lp_psind > 1
1635 #endif
1636 )
1637 return (EINVAL);
1638 align = pagesizes[shmfd->shm_lp_psind];
1639 } else {
1640 align >>= MAP_ALIGNMENT_SHIFT;
1641 align = 1ULL << align;
1642 /* Also handles overflow. */
1643 if (align < pagesizes[shmfd->shm_lp_psind])
1644 return (EINVAL);
1645 }
1646
1647 vm_map_lock(map);
1648 if ((flags & MAP_FIXED) == 0) {
1649 try = 1;
1650 if (curmap && (*addr == 0 ||
1651 (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1652 *addr < round_page((vm_offset_t)vms->vm_daddr +
1653 lim_max(td, RLIMIT_DATA))))) {
1654 *addr = roundup2((vm_offset_t)vms->vm_daddr +
1655 lim_max(td, RLIMIT_DATA),
1656 pagesizes[shmfd->shm_lp_psind]);
1657 }
1658 again:
1659 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1660 if (rv != KERN_SUCCESS) {
1661 if (try == 1) {
1662 try = 2;
1663 *addr = vm_map_min(map);
1664 if ((*addr & mask) != 0)
1665 *addr = (*addr + mask) & mask;
1666 goto again;
1667 }
1668 goto fail1;
1669 }
1670 } else if ((flags & MAP_EXCL) == 0) {
1671 rv = vm_map_delete(map, *addr, *addr + size);
1672 if (rv != KERN_SUCCESS)
1673 goto fail1;
1674 } else {
1675 error = ENOSPC;
1676 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1677 goto fail;
1678 next_entry = vm_map_entry_succ(prev_entry);
1679 if (next_entry->start < *addr + size)
1680 goto fail;
1681 }
1682
1683 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1684 prot, max_prot, docow);
1685 fail1:
1686 error = vm_mmap_to_errno(rv);
1687 fail:
1688 vm_map_unlock(map);
1689 return (error);
1690 }
1691
1692 static int
shm_mmap(struct file * fp,vm_map_t map,vm_offset_t * addr,vm_size_t objsize,vm_prot_t prot,vm_prot_t max_maxprot,int flags,vm_ooffset_t foff,struct thread * td)1693 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1694 vm_prot_t prot, vm_prot_t max_maxprot, int flags,
1695 vm_ooffset_t foff, struct thread *td)
1696 {
1697 struct shmfd *shmfd;
1698 vm_prot_t maxprot;
1699 int error;
1700 bool writecnt;
1701 void *rl_cookie;
1702
1703 shmfd = fp->f_data;
1704 maxprot = VM_PROT_NONE;
1705
1706 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize);
1707 /* FREAD should always be set. */
1708 if ((fp->f_flag & FREAD) != 0)
1709 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1710
1711 /*
1712 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1713 * mapping with a write seal applied. Private mappings are always
1714 * writeable.
1715 */
1716 if ((flags & MAP_SHARED) == 0) {
1717 if ((max_maxprot & VM_PROT_WRITE) != 0)
1718 maxprot |= VM_PROT_WRITE;
1719 writecnt = false;
1720 } else {
1721 if ((fp->f_flag & FWRITE) != 0 &&
1722 (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1723 maxprot |= VM_PROT_WRITE;
1724
1725 /*
1726 * Any mappings from a writable descriptor may be upgraded to
1727 * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1728 * applied between the open and subsequent mmap(2). We want to
1729 * reject application of a write seal as long as any such
1730 * mapping exists so that the seal cannot be trivially bypassed.
1731 */
1732 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1733 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1734 error = EACCES;
1735 goto out;
1736 }
1737 }
1738 maxprot &= max_maxprot;
1739
1740 /* See comment in vn_mmap(). */
1741 if (
1742 #ifdef _LP64
1743 objsize > OFF_MAX ||
1744 #endif
1745 foff > OFF_MAX - objsize) {
1746 error = EINVAL;
1747 goto out;
1748 }
1749
1750 #ifdef MAC
1751 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1752 if (error != 0)
1753 goto out;
1754 #endif
1755
1756 mtx_lock(&shm_timestamp_lock);
1757 vfs_timestamp(&shmfd->shm_atime);
1758 mtx_unlock(&shm_timestamp_lock);
1759 vm_object_reference(shmfd->shm_object);
1760
1761 if (shm_largepage(shmfd)) {
1762 writecnt = false;
1763 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1764 maxprot, flags, foff, td, rl_cookie);
1765 } else {
1766 if (writecnt) {
1767 vm_pager_update_writecount(shmfd->shm_object, 0,
1768 objsize);
1769 }
1770 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1771 shmfd->shm_object, foff, writecnt, td);
1772 }
1773 if (error != 0) {
1774 if (writecnt)
1775 vm_pager_release_writecount(shmfd->shm_object, 0,
1776 objsize);
1777 vm_object_deallocate(shmfd->shm_object);
1778 }
1779 out:
1780 shm_rangelock_unlock(shmfd, rl_cookie);
1781 return (error);
1782 }
1783
1784 static int
shm_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1785 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1786 struct thread *td)
1787 {
1788 struct shmfd *shmfd;
1789 int error;
1790
1791 error = 0;
1792 shmfd = fp->f_data;
1793 mtx_lock(&shm_timestamp_lock);
1794 /*
1795 * SUSv4 says that x bits of permission need not be affected.
1796 * Be consistent with our shm_open there.
1797 */
1798 #ifdef MAC
1799 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1800 if (error != 0)
1801 goto out;
1802 #endif
1803 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1804 VADMIN, active_cred);
1805 if (error != 0)
1806 goto out;
1807 shmfd->shm_mode = mode & ACCESSPERMS;
1808 out:
1809 mtx_unlock(&shm_timestamp_lock);
1810 return (error);
1811 }
1812
1813 static int
shm_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1814 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1815 struct thread *td)
1816 {
1817 struct shmfd *shmfd;
1818 int error;
1819
1820 error = 0;
1821 shmfd = fp->f_data;
1822 mtx_lock(&shm_timestamp_lock);
1823 #ifdef MAC
1824 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1825 if (error != 0)
1826 goto out;
1827 #endif
1828 if (uid == (uid_t)-1)
1829 uid = shmfd->shm_uid;
1830 if (gid == (gid_t)-1)
1831 gid = shmfd->shm_gid;
1832 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1833 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1834 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1835 goto out;
1836 shmfd->shm_uid = uid;
1837 shmfd->shm_gid = gid;
1838 out:
1839 mtx_unlock(&shm_timestamp_lock);
1840 return (error);
1841 }
1842
1843 /*
1844 * Helper routines to allow the backing object of a shared memory file
1845 * descriptor to be mapped in the kernel.
1846 */
1847 int
shm_map(struct file * fp,size_t size,off_t offset,void ** memp)1848 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1849 {
1850 struct shmfd *shmfd;
1851 vm_offset_t kva, ofs;
1852 vm_object_t obj;
1853 int rv;
1854
1855 if (fp->f_type != DTYPE_SHM)
1856 return (EINVAL);
1857 shmfd = fp->f_data;
1858 obj = shmfd->shm_object;
1859 VM_OBJECT_WLOCK(obj);
1860 /*
1861 * XXXRW: This validation is probably insufficient, and subject to
1862 * sign errors. It should be fixed.
1863 */
1864 if (offset >= shmfd->shm_size ||
1865 offset + size > round_page(shmfd->shm_size)) {
1866 VM_OBJECT_WUNLOCK(obj);
1867 return (EINVAL);
1868 }
1869
1870 shmfd->shm_kmappings++;
1871 vm_object_reference_locked(obj);
1872 VM_OBJECT_WUNLOCK(obj);
1873
1874 /* Map the object into the kernel_map and wire it. */
1875 kva = vm_map_min(kernel_map);
1876 ofs = offset & PAGE_MASK;
1877 offset = trunc_page(offset);
1878 size = round_page(size + ofs);
1879 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1880 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1881 VM_PROT_READ | VM_PROT_WRITE, 0);
1882 if (rv == KERN_SUCCESS) {
1883 rv = vm_map_wire(kernel_map, kva, kva + size,
1884 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1885 if (rv == KERN_SUCCESS) {
1886 *memp = (void *)(kva + ofs);
1887 return (0);
1888 }
1889 vm_map_remove(kernel_map, kva, kva + size);
1890 } else
1891 vm_object_deallocate(obj);
1892
1893 /* On failure, drop our mapping reference. */
1894 VM_OBJECT_WLOCK(obj);
1895 shmfd->shm_kmappings--;
1896 VM_OBJECT_WUNLOCK(obj);
1897
1898 return (vm_mmap_to_errno(rv));
1899 }
1900
1901 /*
1902 * We require the caller to unmap the entire entry. This allows us to
1903 * safely decrement shm_kmappings when a mapping is removed.
1904 */
1905 int
shm_unmap(struct file * fp,void * mem,size_t size)1906 shm_unmap(struct file *fp, void *mem, size_t size)
1907 {
1908 struct shmfd *shmfd;
1909 vm_map_entry_t entry;
1910 vm_offset_t kva, ofs;
1911 vm_object_t obj;
1912 vm_pindex_t pindex;
1913 vm_prot_t prot;
1914 boolean_t wired;
1915 vm_map_t map;
1916 int rv;
1917
1918 if (fp->f_type != DTYPE_SHM)
1919 return (EINVAL);
1920 shmfd = fp->f_data;
1921 kva = (vm_offset_t)mem;
1922 ofs = kva & PAGE_MASK;
1923 kva = trunc_page(kva);
1924 size = round_page(size + ofs);
1925 map = kernel_map;
1926 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1927 &obj, &pindex, &prot, &wired);
1928 if (rv != KERN_SUCCESS)
1929 return (EINVAL);
1930 if (entry->start != kva || entry->end != kva + size) {
1931 vm_map_lookup_done(map, entry);
1932 return (EINVAL);
1933 }
1934 vm_map_lookup_done(map, entry);
1935 if (obj != shmfd->shm_object)
1936 return (EINVAL);
1937 vm_map_remove(map, kva, kva + size);
1938 VM_OBJECT_WLOCK(obj);
1939 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1940 shmfd->shm_kmappings--;
1941 VM_OBJECT_WUNLOCK(obj);
1942 return (0);
1943 }
1944
1945 static int
shm_fill_kinfo_locked(struct shmfd * shmfd,struct kinfo_file * kif,bool list)1946 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1947 {
1948 const char *path, *pr_path;
1949 size_t pr_pathlen;
1950 bool visible;
1951
1952 sx_assert(&shm_dict_lock, SA_LOCKED);
1953 kif->kf_type = KF_TYPE_SHM;
1954 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1955 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1956 if (shmfd->shm_path != NULL) {
1957 path = shmfd->shm_path;
1958 pr_path = curthread->td_ucred->cr_prison->pr_path;
1959 if (strcmp(pr_path, "/") != 0) {
1960 /* Return the jail-rooted pathname. */
1961 pr_pathlen = strlen(pr_path);
1962 visible = strncmp(path, pr_path, pr_pathlen) == 0 &&
1963 path[pr_pathlen] == '/';
1964 if (list && !visible)
1965 return (EPERM);
1966 if (visible)
1967 path += pr_pathlen;
1968 }
1969 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1970 }
1971 return (0);
1972 }
1973
1974 static int
shm_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp __unused)1975 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1976 struct filedesc *fdp __unused)
1977 {
1978 int res;
1979
1980 sx_slock(&shm_dict_lock);
1981 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1982 sx_sunlock(&shm_dict_lock);
1983 return (res);
1984 }
1985
1986 static int
shm_add_seals(struct file * fp,int seals)1987 shm_add_seals(struct file *fp, int seals)
1988 {
1989 struct shmfd *shmfd;
1990 void *rl_cookie;
1991 vm_ooffset_t writemappings;
1992 int error, nseals;
1993
1994 error = 0;
1995 shmfd = fp->f_data;
1996 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1997
1998 /* Even already-set seals should result in EPERM. */
1999 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
2000 error = EPERM;
2001 goto out;
2002 }
2003 nseals = seals & ~shmfd->shm_seals;
2004 if ((nseals & F_SEAL_WRITE) != 0) {
2005 if (shm_largepage(shmfd)) {
2006 error = ENOTSUP;
2007 goto out;
2008 }
2009
2010 /*
2011 * The rangelock above prevents writable mappings from being
2012 * added after we've started applying seals. The RLOCK here
2013 * is to avoid torn reads on ILP32 arches as unmapping/reducing
2014 * writemappings will be done without a rangelock.
2015 */
2016 VM_OBJECT_RLOCK(shmfd->shm_object);
2017 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
2018 VM_OBJECT_RUNLOCK(shmfd->shm_object);
2019 /* kmappings are also writable */
2020 if (writemappings > 0) {
2021 error = EBUSY;
2022 goto out;
2023 }
2024 }
2025 shmfd->shm_seals |= nseals;
2026 out:
2027 shm_rangelock_unlock(shmfd, rl_cookie);
2028 return (error);
2029 }
2030
2031 static int
shm_get_seals(struct file * fp,int * seals)2032 shm_get_seals(struct file *fp, int *seals)
2033 {
2034 struct shmfd *shmfd;
2035
2036 shmfd = fp->f_data;
2037 *seals = shmfd->shm_seals;
2038 return (0);
2039 }
2040
2041 static int
shm_deallocate(struct shmfd * shmfd,off_t * offset,off_t * length,int flags)2042 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
2043 {
2044 vm_object_t object;
2045 vm_pindex_t pistart, pi, piend;
2046 vm_ooffset_t off, len;
2047 int startofs, endofs, end;
2048 int error;
2049
2050 off = *offset;
2051 len = *length;
2052 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
2053 if (off + len > shmfd->shm_size)
2054 len = shmfd->shm_size - off;
2055 object = shmfd->shm_object;
2056 startofs = off & PAGE_MASK;
2057 endofs = (off + len) & PAGE_MASK;
2058 pistart = OFF_TO_IDX(off);
2059 piend = OFF_TO_IDX(off + len);
2060 pi = OFF_TO_IDX(off + PAGE_MASK);
2061 error = 0;
2062
2063 /* Handle the case when offset is on or beyond shm size. */
2064 if ((off_t)len <= 0) {
2065 *length = 0;
2066 return (0);
2067 }
2068
2069 VM_OBJECT_WLOCK(object);
2070
2071 if (startofs != 0) {
2072 end = pistart != piend ? PAGE_SIZE : endofs;
2073 error = shm_partial_page_invalidate(object, pistart, startofs,
2074 end);
2075 if (error)
2076 goto out;
2077 off += end - startofs;
2078 len -= end - startofs;
2079 }
2080
2081 if (pi < piend) {
2082 vm_object_page_remove(object, pi, piend, 0);
2083 off += IDX_TO_OFF(piend - pi);
2084 len -= IDX_TO_OFF(piend - pi);
2085 }
2086
2087 if (endofs != 0 && pistart != piend) {
2088 error = shm_partial_page_invalidate(object, piend, 0, endofs);
2089 if (error)
2090 goto out;
2091 off += endofs;
2092 len -= endofs;
2093 }
2094
2095 out:
2096 VM_OBJECT_WUNLOCK(shmfd->shm_object);
2097 *offset = off;
2098 *length = len;
2099 return (error);
2100 }
2101
2102 static int
shm_fspacectl(struct file * fp,int cmd,off_t * offset,off_t * length,int flags,struct ucred * active_cred,struct thread * td)2103 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
2104 struct ucred *active_cred, struct thread *td)
2105 {
2106 void *rl_cookie;
2107 struct shmfd *shmfd;
2108 off_t off, len;
2109 int error;
2110
2111 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
2112 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
2113 ("shm_fspacectl: non-zero flags"));
2114 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
2115 ("shm_fspacectl: offset/length overflow or underflow"));
2116
2117 shmfd = fp->f_data;
2118 off = *offset;
2119 len = *length;
2120
2121 if (shm_largepage(shmfd))
2122 return (ENOTSUP);
2123
2124 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len);
2125 switch (cmd) {
2126 case SPACECTL_DEALLOC:
2127 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2128 error = EPERM;
2129 break;
2130 }
2131 error = shm_deallocate(shmfd, &off, &len, flags);
2132 *offset = off;
2133 *length = len;
2134 break;
2135 default:
2136 __assert_unreachable();
2137 }
2138 shm_rangelock_unlock(shmfd, rl_cookie);
2139 return (error);
2140 }
2141
2142
2143 static int
shm_fallocate(struct file * fp,off_t offset,off_t len,struct thread * td)2144 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2145 {
2146 void *rl_cookie;
2147 struct shmfd *shmfd;
2148 size_t size;
2149 int error;
2150
2151 /* This assumes that the caller already checked for overflow. */
2152 error = 0;
2153 shmfd = fp->f_data;
2154 size = offset + len;
2155
2156 /*
2157 * Just grab the rangelock for the range that we may be attempting to
2158 * grow, rather than blocking read/write for regions we won't be
2159 * touching while this (potential) resize is in progress. Other
2160 * attempts to resize the shmfd will have to take a write lock from 0 to
2161 * OFF_MAX, so this being potentially beyond the current usable range of
2162 * the shmfd is not necessarily a concern. If other mechanisms are
2163 * added to grow a shmfd, this may need to be re-evaluated.
2164 */
2165 rl_cookie = shm_rangelock_wlock(shmfd, offset, size);
2166 if (size > shmfd->shm_size)
2167 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2168 shm_rangelock_unlock(shmfd, rl_cookie);
2169 /* Translate to posix_fallocate(2) return value as needed. */
2170 if (error == ENOMEM)
2171 error = ENOSPC;
2172 return (error);
2173 }
2174
2175 static int
sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)2176 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2177 {
2178 struct shm_mapping *shmm;
2179 struct sbuf sb;
2180 struct kinfo_file kif = {};
2181 u_long i;
2182 int error, error2;
2183
2184 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2185 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2186 error = 0;
2187 sx_slock(&shm_dict_lock);
2188 for (i = 0; i < shm_hash + 1; i++) {
2189 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2190 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2191 &kif, true);
2192 if (error == EPERM) {
2193 error = 0;
2194 continue;
2195 }
2196 if (error != 0)
2197 break;
2198 pack_kinfo(&kif);
2199 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2200 0 : ENOMEM;
2201 if (error != 0)
2202 break;
2203 }
2204 }
2205 sx_sunlock(&shm_dict_lock);
2206 error2 = sbuf_finish(&sb);
2207 sbuf_delete(&sb);
2208 return (error != 0 ? error : error2);
2209 }
2210
2211 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2212 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2213 NULL, 0, sysctl_posix_shm_list, "",
2214 "POSIX SHM list");
2215
2216 int
kern_shm_open(struct thread * td,const char * path,int flags,mode_t mode,struct filecaps * caps)2217 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2218 struct filecaps *caps)
2219 {
2220
2221 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL, NULL));
2222 }
2223
2224 /*
2225 * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2226 * caller, and libc will enforce it for the traditional shm_open() call. This
2227 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
2228 * interface also includes a 'name' argument that is currently unused, but could
2229 * potentially be exported later via some interface for debugging purposes.
2230 * From the kernel's perspective, it is optional. Individual consumers like
2231 * memfd_create() may require it in order to be compatible with other systems
2232 * implementing the same function.
2233 */
2234 int
sys_shm_open2(struct thread * td,struct shm_open2_args * uap)2235 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2236 {
2237
2238 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2239 uap->shmflags, NULL, uap->name, NULL));
2240 }
2241
2242 int
shm_get_path(struct vm_object * obj,char * path,size_t sz)2243 shm_get_path(struct vm_object *obj, char *path, size_t sz)
2244 {
2245 struct shmfd *shmfd;
2246 int error;
2247
2248 error = 0;
2249 shmfd = NULL;
2250 sx_slock(&shm_dict_lock);
2251 VM_OBJECT_RLOCK(obj);
2252 if ((obj->flags & OBJ_POSIXSHM) == 0) {
2253 error = EINVAL;
2254 } else {
2255 if (obj->type == shmfd_pager_type)
2256 shmfd = obj->un_pager.swp.swp_priv;
2257 else if (obj->type == OBJT_PHYS)
2258 shmfd = obj->un_pager.phys.phys_priv;
2259 if (shmfd == NULL) {
2260 error = ENXIO;
2261 } else {
2262 strlcpy(path, shmfd->shm_path == NULL ? "anon" :
2263 shmfd->shm_path, sz);
2264 }
2265 }
2266 if (error != 0)
2267 path[0] = '\0';
2268 VM_OBJECT_RUNLOCK(obj);
2269 sx_sunlock(&shm_dict_lock);
2270 return (error);
2271 }
2272