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/swap_pager.h>
104
105 struct shm_mapping {
106 char *sm_path;
107 Fnv32_t sm_fnv;
108 struct shmfd *sm_shmfd;
109 LIST_ENTRY(shm_mapping) sm_link;
110 };
111
112 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
113 static LIST_HEAD(, shm_mapping) *shm_dictionary;
114 static struct sx shm_dict_lock;
115 static struct mtx shm_timestamp_lock;
116 static u_long shm_hash;
117 static struct unrhdr64 shm_ino_unr;
118 static dev_t shm_dev_ino;
119
120 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
121
122 static void shm_init(void *arg);
123 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
124 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
125 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
126 static void shm_doremove(struct shm_mapping *map);
127 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length,
128 void *rl_cookie);
129 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length,
130 void *rl_cookie);
131 static int shm_copyin_path(struct thread *td, const char *userpath_in,
132 char **path_out);
133 static int shm_deallocate(struct shmfd *shmfd, off_t *offset,
134 off_t *length, int flags);
135
136 static fo_rdwr_t shm_read;
137 static fo_rdwr_t shm_write;
138 static fo_truncate_t shm_truncate;
139 static fo_ioctl_t shm_ioctl;
140 static fo_stat_t shm_stat;
141 static fo_close_t shm_close;
142 static fo_chmod_t shm_chmod;
143 static fo_chown_t shm_chown;
144 static fo_seek_t shm_seek;
145 static fo_fill_kinfo_t shm_fill_kinfo;
146 static fo_mmap_t shm_mmap;
147 static fo_get_seals_t shm_get_seals;
148 static fo_add_seals_t shm_add_seals;
149 static fo_fallocate_t shm_fallocate;
150 static fo_fspacectl_t shm_fspacectl;
151
152 /* File descriptor operations. */
153 const struct fileops shm_ops = {
154 .fo_read = shm_read,
155 .fo_write = shm_write,
156 .fo_truncate = shm_truncate,
157 .fo_ioctl = shm_ioctl,
158 .fo_poll = invfo_poll,
159 .fo_kqfilter = invfo_kqfilter,
160 .fo_stat = shm_stat,
161 .fo_close = shm_close,
162 .fo_chmod = shm_chmod,
163 .fo_chown = shm_chown,
164 .fo_sendfile = vn_sendfile,
165 .fo_seek = shm_seek,
166 .fo_fill_kinfo = shm_fill_kinfo,
167 .fo_mmap = shm_mmap,
168 .fo_get_seals = shm_get_seals,
169 .fo_add_seals = shm_add_seals,
170 .fo_fallocate = shm_fallocate,
171 .fo_fspacectl = shm_fspacectl,
172 .fo_cmp = file_kcmp_generic,
173 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE,
174 };
175
176 FEATURE(posix_shm, "POSIX shared memory");
177
178 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
179 "");
180
181 static int largepage_reclaim_tries = 1;
182 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries,
183 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0,
184 "Number of contig reclaims before giving up for default alloc policy");
185
186 #define shm_rangelock_unlock(shmfd, cookie) \
187 rangelock_unlock(&(shmfd)->shm_rl, (cookie), &(shmfd)->shm_mtx)
188 #define shm_rangelock_rlock(shmfd, start, end) \
189 rangelock_rlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
190 #define shm_rangelock_tryrlock(shmfd, start, end) \
191 rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
192 #define shm_rangelock_wlock(shmfd, start, end) \
193 rangelock_wlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx)
194
195 static int
uiomove_object_page(vm_object_t obj,size_t len,struct uio * uio)196 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
197 {
198 vm_page_t m;
199 vm_pindex_t idx;
200 size_t tlen;
201 int error, offset, rv;
202
203 idx = OFF_TO_IDX(uio->uio_offset);
204 offset = uio->uio_offset & PAGE_MASK;
205 tlen = MIN(PAGE_SIZE - offset, len);
206
207 rv = vm_page_grab_valid_unlocked(&m, obj, idx,
208 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT);
209 if (rv == VM_PAGER_OK)
210 goto found;
211
212 /*
213 * Read I/O without either a corresponding resident page or swap
214 * page: use zero_region. This is intended to avoid instantiating
215 * pages on read from a sparse region.
216 */
217 VM_OBJECT_WLOCK(obj);
218 m = vm_page_lookup(obj, idx);
219 if (uio->uio_rw == UIO_READ && m == NULL &&
220 !vm_pager_has_page(obj, idx, NULL, NULL)) {
221 VM_OBJECT_WUNLOCK(obj);
222 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
223 }
224
225 /*
226 * Although the tmpfs vnode lock is held here, it is
227 * nonetheless safe to sleep waiting for a free page. The
228 * pageout daemon does not need to acquire the tmpfs vnode
229 * lock to page out tobj's pages because tobj is a OBJT_SWAP
230 * type object.
231 */
232 rv = vm_page_grab_valid(&m, obj, idx,
233 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY);
234 if (rv != VM_PAGER_OK) {
235 VM_OBJECT_WUNLOCK(obj);
236 if (bootverbose) {
237 printf("uiomove_object: vm_obj %p idx %jd "
238 "pager error %d\n", obj, idx, rv);
239 }
240 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO);
241 }
242 VM_OBJECT_WUNLOCK(obj);
243
244 found:
245 error = uiomove_fromphys(&m, offset, tlen, uio);
246 if (uio->uio_rw == UIO_WRITE && error == 0)
247 vm_page_set_dirty(m);
248 vm_page_activate(m);
249 vm_page_sunbusy(m);
250
251 return (error);
252 }
253
254 int
uiomove_object(vm_object_t obj,off_t obj_size,struct uio * uio)255 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
256 {
257 ssize_t resid;
258 size_t len;
259 int error;
260
261 error = 0;
262 while ((resid = uio->uio_resid) > 0) {
263 if (obj_size <= uio->uio_offset)
264 break;
265 len = MIN(obj_size - uio->uio_offset, resid);
266 if (len == 0)
267 break;
268 error = uiomove_object_page(obj, len, uio);
269 if (error != 0 || resid == uio->uio_resid)
270 break;
271 }
272 return (error);
273 }
274
275 static u_long count_largepages[MAXPAGESIZES];
276
277 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)278 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx,
279 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
280 {
281 vm_page_t m __diagused;
282 int psind;
283
284 psind = object->un_pager.phys.data_val;
285 if (psind == 0 || pidx >= object->size)
286 return (VM_PAGER_FAIL);
287 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE);
288
289 /*
290 * We only busy the first page in the superpage run. It is
291 * useless to busy whole run since we only remove full
292 * superpage, and it takes too long to busy e.g. 512 * 512 ==
293 * 262144 pages constituing 1G amd64 superage.
294 */
295 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT);
296 MPASS(m != NULL);
297
298 *last = *first + atop(pagesizes[psind]) - 1;
299 return (VM_PAGER_OK);
300 }
301
302 static boolean_t
shm_largepage_phys_haspage(vm_object_t object,vm_pindex_t pindex,int * before,int * after)303 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex,
304 int *before, int *after)
305 {
306 int psind;
307
308 psind = object->un_pager.phys.data_val;
309 if (psind == 0 || pindex >= object->size)
310 return (FALSE);
311 if (before != NULL) {
312 *before = pindex - rounddown2(pindex, pagesizes[psind] /
313 PAGE_SIZE);
314 }
315 if (after != NULL) {
316 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) -
317 pindex;
318 }
319 return (TRUE);
320 }
321
322 static void
shm_largepage_phys_ctor(vm_object_t object,vm_prot_t prot,vm_ooffset_t foff,struct ucred * cred)323 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot,
324 vm_ooffset_t foff, struct ucred *cred)
325 {
326 }
327
328 static void
shm_largepage_phys_dtor(vm_object_t object)329 shm_largepage_phys_dtor(vm_object_t object)
330 {
331 int psind;
332
333 psind = object->un_pager.phys.data_val;
334 if (psind != 0) {
335 atomic_subtract_long(&count_largepages[psind],
336 object->size / (pagesizes[psind] / PAGE_SIZE));
337 vm_wire_sub(object->size);
338 } else {
339 KASSERT(object->size == 0,
340 ("largepage phys obj %p not initialized bit size %#jx > 0",
341 object, (uintmax_t)object->size));
342 }
343 }
344
345 static const struct phys_pager_ops shm_largepage_phys_ops = {
346 .phys_pg_populate = shm_largepage_phys_populate,
347 .phys_pg_haspage = shm_largepage_phys_haspage,
348 .phys_pg_ctor = shm_largepage_phys_ctor,
349 .phys_pg_dtor = shm_largepage_phys_dtor,
350 };
351
352 bool
shm_largepage(struct shmfd * shmfd)353 shm_largepage(struct shmfd *shmfd)
354 {
355 return (shmfd->shm_object->type == OBJT_PHYS);
356 }
357
358 static void
shm_pager_freespace(vm_object_t obj,vm_pindex_t start,vm_size_t size)359 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size)
360 {
361 struct shmfd *shm;
362 vm_size_t c;
363
364 swap_pager_freespace(obj, start, size, &c);
365 if (c == 0)
366 return;
367
368 shm = obj->un_pager.swp.swp_priv;
369 if (shm == NULL)
370 return;
371 KASSERT(shm->shm_pages >= c,
372 ("shm %p pages %jd free %jd", shm,
373 (uintmax_t)shm->shm_pages, (uintmax_t)c));
374 shm->shm_pages -= c;
375 }
376
377 static void
shm_page_inserted(vm_object_t obj,vm_page_t m)378 shm_page_inserted(vm_object_t obj, vm_page_t m)
379 {
380 struct shmfd *shm;
381
382 shm = obj->un_pager.swp.swp_priv;
383 if (shm == NULL)
384 return;
385 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL))
386 shm->shm_pages += 1;
387 }
388
389 static void
shm_page_removed(vm_object_t obj,vm_page_t m)390 shm_page_removed(vm_object_t obj, vm_page_t m)
391 {
392 struct shmfd *shm;
393
394 shm = obj->un_pager.swp.swp_priv;
395 if (shm == NULL)
396 return;
397 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) {
398 KASSERT(shm->shm_pages >= 1,
399 ("shm %p pages %jd free 1", shm,
400 (uintmax_t)shm->shm_pages));
401 shm->shm_pages -= 1;
402 }
403 }
404
405 static struct pagerops shm_swap_pager_ops = {
406 .pgo_kvme_type = KVME_TYPE_SWAP,
407 .pgo_freespace = shm_pager_freespace,
408 .pgo_page_inserted = shm_page_inserted,
409 .pgo_page_removed = shm_page_removed,
410 };
411 static int shmfd_pager_type = -1;
412
413 static int
shm_seek(struct file * fp,off_t offset,int whence,struct thread * td)414 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
415 {
416 struct shmfd *shmfd;
417 off_t foffset;
418 int error;
419
420 shmfd = fp->f_data;
421 foffset = foffset_lock(fp, 0);
422 error = 0;
423 switch (whence) {
424 case L_INCR:
425 if (foffset < 0 ||
426 (offset > 0 && foffset > OFF_MAX - offset)) {
427 error = EOVERFLOW;
428 break;
429 }
430 offset += foffset;
431 break;
432 case L_XTND:
433 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
434 error = EOVERFLOW;
435 break;
436 }
437 offset += shmfd->shm_size;
438 break;
439 case L_SET:
440 break;
441 default:
442 error = EINVAL;
443 }
444 if (error == 0) {
445 if (offset < 0 || offset > shmfd->shm_size)
446 error = EINVAL;
447 else
448 td->td_uretoff.tdu_off = offset;
449 }
450 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
451 return (error);
452 }
453
454 static int
shm_read(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)455 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
456 int flags, struct thread *td)
457 {
458 struct shmfd *shmfd;
459 void *rl_cookie;
460 int error;
461
462 shmfd = fp->f_data;
463 #ifdef MAC
464 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
465 if (error)
466 return (error);
467 #endif
468 foffset_lock_uio(fp, uio, flags);
469 rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset,
470 uio->uio_offset + uio->uio_resid);
471 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
472 shm_rangelock_unlock(shmfd, rl_cookie);
473 foffset_unlock_uio(fp, uio, flags);
474 return (error);
475 }
476
477 static int
shm_write(struct file * fp,struct uio * uio,struct ucred * active_cred,int flags,struct thread * td)478 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
479 int flags, struct thread *td)
480 {
481 struct shmfd *shmfd;
482 void *rl_cookie;
483 int error;
484 off_t newsize;
485
486 KASSERT((flags & FOF_OFFSET) == 0 || uio->uio_offset >= 0,
487 ("%s: negative offset", __func__));
488
489 shmfd = fp->f_data;
490 #ifdef MAC
491 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
492 if (error)
493 return (error);
494 #endif
495 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0)
496 return (EINVAL);
497 foffset_lock_uio(fp, uio, flags);
498 if (uio->uio_resid > OFF_MAX - uio->uio_offset) {
499 /*
500 * Overflow is only an error if we're supposed to expand on
501 * write. Otherwise, we'll just truncate the write to the
502 * size of the file, which can only grow up to OFF_MAX.
503 */
504 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) {
505 foffset_unlock_uio(fp, uio, flags);
506 return (EFBIG);
507 }
508
509 newsize = atomic_load_64(&shmfd->shm_size);
510 } else {
511 newsize = uio->uio_offset + uio->uio_resid;
512 }
513 if ((flags & FOF_OFFSET) == 0)
514 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
515 else
516 rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset,
517 MAX(newsize, uio->uio_offset));
518 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
519 error = EPERM;
520 } else {
521 error = 0;
522 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 &&
523 newsize > shmfd->shm_size) {
524 error = shm_dotruncate_cookie(shmfd, newsize,
525 rl_cookie);
526 }
527 if (error == 0)
528 error = uiomove_object(shmfd->shm_object,
529 shmfd->shm_size, uio);
530 }
531 shm_rangelock_unlock(shmfd, rl_cookie);
532 foffset_unlock_uio(fp, uio, flags);
533 return (error);
534 }
535
536 static int
shm_truncate(struct file * fp,off_t length,struct ucred * active_cred,struct thread * td)537 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
538 struct thread *td)
539 {
540 struct shmfd *shmfd;
541 #ifdef MAC
542 int error;
543 #endif
544
545 shmfd = fp->f_data;
546 #ifdef MAC
547 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
548 if (error)
549 return (error);
550 #endif
551 return (shm_dotruncate(shmfd, length));
552 }
553
554 int
shm_ioctl(struct file * fp,u_long com,void * data,struct ucred * active_cred,struct thread * td)555 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
556 struct thread *td)
557 {
558 struct shmfd *shmfd;
559 struct shm_largepage_conf *conf;
560 void *rl_cookie;
561
562 shmfd = fp->f_data;
563 switch (com) {
564 case FIONBIO:
565 case FIOASYNC:
566 /*
567 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
568 * just like it would on an unlinked regular file
569 */
570 return (0);
571 case FIOSSHMLPGCNF:
572 if (!shm_largepage(shmfd))
573 return (ENOTTY);
574 conf = data;
575 if (shmfd->shm_lp_psind != 0 &&
576 conf->psind != shmfd->shm_lp_psind)
577 return (EINVAL);
578 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES ||
579 pagesizes[conf->psind] == 0)
580 return (EINVAL);
581 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT &&
582 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT &&
583 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD)
584 return (EINVAL);
585
586 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
587 shmfd->shm_lp_psind = conf->psind;
588 shmfd->shm_lp_alloc_policy = conf->alloc_policy;
589 shmfd->shm_object->un_pager.phys.data_val = conf->psind;
590 shm_rangelock_unlock(shmfd, rl_cookie);
591 return (0);
592 case FIOGSHMLPGCNF:
593 if (!shm_largepage(shmfd))
594 return (ENOTTY);
595 conf = data;
596 rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX);
597 conf->psind = shmfd->shm_lp_psind;
598 conf->alloc_policy = shmfd->shm_lp_alloc_policy;
599 shm_rangelock_unlock(shmfd, rl_cookie);
600 return (0);
601 default:
602 return (ENOTTY);
603 }
604 }
605
606 static int
shm_stat(struct file * fp,struct stat * sb,struct ucred * active_cred)607 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred)
608 {
609 struct shmfd *shmfd;
610 #ifdef MAC
611 int error;
612 #endif
613
614 shmfd = fp->f_data;
615
616 #ifdef MAC
617 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
618 if (error)
619 return (error);
620 #endif
621
622 /*
623 * Attempt to return sanish values for fstat() on a memory file
624 * descriptor.
625 */
626 bzero(sb, sizeof(*sb));
627 sb->st_blksize = PAGE_SIZE;
628 sb->st_size = shmfd->shm_size;
629 mtx_lock(&shm_timestamp_lock);
630 sb->st_atim = shmfd->shm_atime;
631 sb->st_ctim = shmfd->shm_ctime;
632 sb->st_mtim = shmfd->shm_mtime;
633 sb->st_birthtim = shmfd->shm_birthtime;
634 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
635 sb->st_uid = shmfd->shm_uid;
636 sb->st_gid = shmfd->shm_gid;
637 mtx_unlock(&shm_timestamp_lock);
638 sb->st_dev = shm_dev_ino;
639 sb->st_ino = shmfd->shm_ino;
640 sb->st_nlink = shmfd->shm_object->ref_count;
641 if (shm_largepage(shmfd)) {
642 sb->st_blocks = shmfd->shm_object->size /
643 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT);
644 } else {
645 sb->st_blocks = shmfd->shm_pages;
646 }
647
648 return (0);
649 }
650
651 static int
shm_close(struct file * fp,struct thread * td)652 shm_close(struct file *fp, struct thread *td)
653 {
654 struct shmfd *shmfd;
655
656 shmfd = fp->f_data;
657 fp->f_data = NULL;
658 shm_drop(shmfd);
659
660 return (0);
661 }
662
663 static int
shm_copyin_path(struct thread * td,const char * userpath_in,char ** path_out)664 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) {
665 int error;
666 char *path;
667 const char *pr_path;
668 size_t pr_pathlen;
669
670 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
671 pr_path = td->td_ucred->cr_prison->pr_path;
672
673 /* Construct a full pathname for jailed callers. */
674 pr_pathlen = strcmp(pr_path, "/") ==
675 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN);
676 error = copyinstr(userpath_in, path + pr_pathlen,
677 MAXPATHLEN - pr_pathlen, NULL);
678 if (error != 0)
679 goto out;
680
681 #ifdef KTRACE
682 if (KTRPOINT(curthread, KTR_NAMEI))
683 ktrnamei(path);
684 #endif
685
686 /* Require paths to start with a '/' character. */
687 if (path[pr_pathlen] != '/') {
688 error = EINVAL;
689 goto out;
690 }
691
692 *path_out = path;
693
694 out:
695 if (error != 0)
696 free(path, M_SHMFD);
697
698 return (error);
699 }
700
701 static int
shm_partial_page_invalidate(vm_object_t object,vm_pindex_t idx,int base,int end)702 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base,
703 int end)
704 {
705 vm_page_t m;
706 int rv;
707
708 VM_OBJECT_ASSERT_WLOCKED(object);
709 KASSERT(base >= 0, ("%s: base %d", __func__, base));
710 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base,
711 end));
712
713 retry:
714 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT);
715 if (m != NULL) {
716 MPASS(vm_page_all_valid(m));
717 } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
718 m = vm_page_alloc(object, idx,
719 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
720 if (m == NULL)
721 goto retry;
722 vm_object_pip_add(object, 1);
723 VM_OBJECT_WUNLOCK(object);
724 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL);
725 VM_OBJECT_WLOCK(object);
726 vm_object_pip_wakeup(object);
727 if (rv == VM_PAGER_OK) {
728 /*
729 * Since the page was not resident, and therefore not
730 * recently accessed, immediately enqueue it for
731 * asynchronous laundering. The current operation is
732 * not regarded as an access.
733 */
734 vm_page_launder(m);
735 } else {
736 vm_page_free(m);
737 VM_OBJECT_WUNLOCK(object);
738 return (EIO);
739 }
740 }
741 if (m != NULL) {
742 pmap_zero_page_area(m, base, end - base);
743 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid",
744 __func__, m));
745 vm_page_set_dirty(m);
746 vm_page_xunbusy(m);
747 }
748
749 return (0);
750 }
751
752 static int
shm_dotruncate_locked(struct shmfd * shmfd,off_t length,void * rl_cookie)753 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
754 {
755 vm_object_t object;
756 vm_pindex_t nobjsize;
757 vm_ooffset_t delta;
758 int base, error;
759
760 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
761 object = shmfd->shm_object;
762 VM_OBJECT_ASSERT_WLOCKED(object);
763 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
764 if (length == shmfd->shm_size)
765 return (0);
766 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
767
768 /* Are we shrinking? If so, trim the end. */
769 if (length < shmfd->shm_size) {
770 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
771 return (EPERM);
772
773 /*
774 * Disallow any requests to shrink the size if this
775 * object is mapped into the kernel.
776 */
777 if (shmfd->shm_kmappings > 0)
778 return (EBUSY);
779
780 /*
781 * Zero the truncated part of the last page.
782 */
783 base = length & PAGE_MASK;
784 if (base != 0) {
785 error = shm_partial_page_invalidate(object,
786 OFF_TO_IDX(length), base, PAGE_SIZE);
787 if (error)
788 return (error);
789 }
790 delta = IDX_TO_OFF(object->size - nobjsize);
791
792 if (nobjsize < object->size)
793 vm_object_page_remove(object, nobjsize, object->size,
794 0);
795
796 /* Free the swap accounted for shm */
797 swap_release_by_cred(delta, object->cred);
798 object->charge -= delta;
799 } else {
800 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
801 return (EPERM);
802
803 /* Try to reserve additional swap space. */
804 delta = IDX_TO_OFF(nobjsize - object->size);
805 if (!swap_reserve_by_cred(delta, object->cred))
806 return (ENOMEM);
807 object->charge += delta;
808 }
809 shmfd->shm_size = length;
810 mtx_lock(&shm_timestamp_lock);
811 vfs_timestamp(&shmfd->shm_ctime);
812 shmfd->shm_mtime = shmfd->shm_ctime;
813 mtx_unlock(&shm_timestamp_lock);
814 object->size = nobjsize;
815 return (0);
816 }
817
818 static int
shm_dotruncate_largepage(struct shmfd * shmfd,off_t length,void * rl_cookie)819 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
820 {
821 vm_object_t object;
822 vm_page_t m;
823 vm_pindex_t newobjsz;
824 vm_pindex_t oldobjsz __unused;
825 int aflags, error, i, psind, try;
826
827 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
828 object = shmfd->shm_object;
829 VM_OBJECT_ASSERT_WLOCKED(object);
830 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
831
832 oldobjsz = object->size;
833 newobjsz = OFF_TO_IDX(length);
834 if (length == shmfd->shm_size)
835 return (0);
836 psind = shmfd->shm_lp_psind;
837 if (psind == 0 && length != 0)
838 return (EINVAL);
839 if ((length & (pagesizes[psind] - 1)) != 0)
840 return (EINVAL);
841
842 if (length < shmfd->shm_size) {
843 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
844 return (EPERM);
845 if (shmfd->shm_kmappings > 0)
846 return (EBUSY);
847 return (ENOTSUP); /* Pages are unmanaged. */
848 #if 0
849 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
850 object->size = newobjsz;
851 shmfd->shm_size = length;
852 return (0);
853 #endif
854 }
855
856 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
857 return (EPERM);
858
859 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
860 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
861 aflags |= VM_ALLOC_WAITFAIL;
862 try = 0;
863
864 /*
865 * Extend shmfd and object, keeping all already fully
866 * allocated large pages intact even on error, because dropped
867 * object lock might allowed mapping of them.
868 */
869 while (object->size < newobjsz) {
870 m = vm_page_alloc_contig(object, object->size, aflags,
871 pagesizes[psind] / PAGE_SIZE, 0, ~0,
872 pagesizes[psind], 0,
873 VM_MEMATTR_DEFAULT);
874 if (m == NULL) {
875 VM_OBJECT_WUNLOCK(object);
876 if (shmfd->shm_lp_alloc_policy ==
877 SHM_LARGEPAGE_ALLOC_NOWAIT ||
878 (shmfd->shm_lp_alloc_policy ==
879 SHM_LARGEPAGE_ALLOC_DEFAULT &&
880 try >= largepage_reclaim_tries)) {
881 VM_OBJECT_WLOCK(object);
882 return (ENOMEM);
883 }
884 error = vm_page_reclaim_contig(aflags,
885 pagesizes[psind] / PAGE_SIZE, 0, ~0,
886 pagesizes[psind], 0) ? 0 :
887 vm_wait_intr(object);
888 if (error != 0) {
889 VM_OBJECT_WLOCK(object);
890 return (error);
891 }
892 try++;
893 VM_OBJECT_WLOCK(object);
894 continue;
895 }
896 try = 0;
897 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
898 if ((m[i].flags & PG_ZERO) == 0)
899 pmap_zero_page(&m[i]);
900 vm_page_valid(&m[i]);
901 vm_page_xunbusy(&m[i]);
902 }
903 object->size += OFF_TO_IDX(pagesizes[psind]);
904 shmfd->shm_size += pagesizes[psind];
905 atomic_add_long(&count_largepages[psind], 1);
906 vm_wire_add(atop(pagesizes[psind]));
907 }
908 return (0);
909 }
910
911 static int
shm_dotruncate_cookie(struct shmfd * shmfd,off_t length,void * rl_cookie)912 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
913 {
914 int error;
915
916 VM_OBJECT_WLOCK(shmfd->shm_object);
917 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
918 length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
919 rl_cookie);
920 VM_OBJECT_WUNLOCK(shmfd->shm_object);
921 return (error);
922 }
923
924 int
shm_dotruncate(struct shmfd * shmfd,off_t length)925 shm_dotruncate(struct shmfd *shmfd, off_t length)
926 {
927 void *rl_cookie;
928 int error;
929
930 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
931 error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
932 shm_rangelock_unlock(shmfd, rl_cookie);
933 return (error);
934 }
935
936 /*
937 * shmfd object management including creation and reference counting
938 * routines.
939 */
940 struct shmfd *
shm_alloc(struct ucred * ucred,mode_t mode,bool largepage)941 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
942 {
943 struct shmfd *shmfd;
944 vm_object_t obj;
945
946 if (largepage) {
947 obj = phys_pager_allocate(NULL, &shm_largepage_phys_ops,
948 NULL, 0, VM_PROT_DEFAULT, 0, ucred);
949 } else {
950 obj = vm_pager_allocate(shmfd_pager_type, NULL, 0,
951 VM_PROT_DEFAULT, 0, ucred);
952 }
953 if (obj == NULL) {
954 /*
955 * swap reservation limits can cause object allocation
956 * to fail.
957 */
958 return (NULL);
959 }
960
961 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
962 shmfd->shm_uid = ucred->cr_uid;
963 shmfd->shm_gid = ucred->cr_gid;
964 shmfd->shm_mode = mode;
965 if (largepage) {
966 obj->un_pager.phys.phys_priv = shmfd;
967 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
968 } else {
969 obj->un_pager.swp.swp_priv = shmfd;
970 }
971
972 VM_OBJECT_WLOCK(obj);
973 vm_object_set_flag(obj, OBJ_POSIXSHM);
974 VM_OBJECT_WUNLOCK(obj);
975 shmfd->shm_object = obj;
976 vfs_timestamp(&shmfd->shm_birthtime);
977 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
978 shmfd->shm_birthtime;
979 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
980 refcount_init(&shmfd->shm_refs, 1);
981 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
982 rangelock_init(&shmfd->shm_rl);
983 #ifdef MAC
984 mac_posixshm_init(shmfd);
985 mac_posixshm_create(ucred, shmfd);
986 #endif
987
988 return (shmfd);
989 }
990
991 struct shmfd *
shm_hold(struct shmfd * shmfd)992 shm_hold(struct shmfd *shmfd)
993 {
994
995 refcount_acquire(&shmfd->shm_refs);
996 return (shmfd);
997 }
998
999 void
shm_drop(struct shmfd * shmfd)1000 shm_drop(struct shmfd *shmfd)
1001 {
1002 vm_object_t obj;
1003
1004 if (refcount_release(&shmfd->shm_refs)) {
1005 #ifdef MAC
1006 mac_posixshm_destroy(shmfd);
1007 #endif
1008 rangelock_destroy(&shmfd->shm_rl);
1009 mtx_destroy(&shmfd->shm_mtx);
1010 obj = shmfd->shm_object;
1011 VM_OBJECT_WLOCK(obj);
1012 if (shm_largepage(shmfd))
1013 obj->un_pager.phys.phys_priv = NULL;
1014 else
1015 obj->un_pager.swp.swp_priv = NULL;
1016 VM_OBJECT_WUNLOCK(obj);
1017 vm_object_deallocate(obj);
1018 free(shmfd, M_SHMFD);
1019 }
1020 }
1021
1022 /*
1023 * Determine if the credentials have sufficient permissions for a
1024 * specified combination of FREAD and FWRITE.
1025 */
1026 int
shm_access(struct shmfd * shmfd,struct ucred * ucred,int flags)1027 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
1028 {
1029 accmode_t accmode;
1030 int error;
1031
1032 accmode = 0;
1033 if (flags & FREAD)
1034 accmode |= VREAD;
1035 if (flags & FWRITE)
1036 accmode |= VWRITE;
1037 mtx_lock(&shm_timestamp_lock);
1038 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1039 accmode, ucred);
1040 mtx_unlock(&shm_timestamp_lock);
1041 return (error);
1042 }
1043
1044 static void
shm_init(void * arg)1045 shm_init(void *arg)
1046 {
1047 char name[32];
1048 int i;
1049
1050 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
1051 sx_init(&shm_dict_lock, "shm dictionary");
1052 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
1053 new_unrhdr64(&shm_ino_unr, 1);
1054 shm_dev_ino = devfs_alloc_cdp_inode();
1055 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
1056 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
1057 OBJT_SWAP);
1058 MPASS(shmfd_pager_type != -1);
1059
1060 for (i = 1; i < MAXPAGESIZES; i++) {
1061 if (pagesizes[i] == 0)
1062 break;
1063 #define M (1024 * 1024)
1064 #define G (1024 * M)
1065 if (pagesizes[i] >= G)
1066 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
1067 else if (pagesizes[i] >= M)
1068 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
1069 else
1070 snprintf(name, sizeof(name), "%lu", pagesizes[i]);
1071 #undef G
1072 #undef M
1073 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
1074 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
1075 "number of non-transient largepages allocated");
1076 }
1077 }
1078 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
1079
1080 /*
1081 * Remove all shared memory objects that belong to a prison.
1082 */
1083 void
shm_remove_prison(struct prison * pr)1084 shm_remove_prison(struct prison *pr)
1085 {
1086 struct shm_mapping *shmm, *tshmm;
1087 u_long i;
1088
1089 sx_xlock(&shm_dict_lock);
1090 for (i = 0; i < shm_hash + 1; i++) {
1091 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
1092 if (shmm->sm_shmfd->shm_object->cred &&
1093 shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1094 shm_doremove(shmm);
1095 }
1096 }
1097 sx_xunlock(&shm_dict_lock);
1098 }
1099
1100 /*
1101 * Dictionary management. We maintain an in-kernel dictionary to map
1102 * paths to shmfd objects. We use the FNV hash on the path to store
1103 * the mappings in a hash table.
1104 */
1105 static struct shmfd *
shm_lookup(char * path,Fnv32_t fnv)1106 shm_lookup(char *path, Fnv32_t fnv)
1107 {
1108 struct shm_mapping *map;
1109
1110 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1111 if (map->sm_fnv != fnv)
1112 continue;
1113 if (strcmp(map->sm_path, path) == 0)
1114 return (map->sm_shmfd);
1115 }
1116
1117 return (NULL);
1118 }
1119
1120 static void
shm_insert(char * path,Fnv32_t fnv,struct shmfd * shmfd)1121 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1122 {
1123 struct shm_mapping *map;
1124
1125 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1126 map->sm_path = path;
1127 map->sm_fnv = fnv;
1128 map->sm_shmfd = shm_hold(shmfd);
1129 shmfd->shm_path = path;
1130 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1131 }
1132
1133 static int
shm_remove(char * path,Fnv32_t fnv,struct ucred * ucred)1134 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1135 {
1136 struct shm_mapping *map;
1137 int error;
1138
1139 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1140 if (map->sm_fnv != fnv)
1141 continue;
1142 if (strcmp(map->sm_path, path) == 0) {
1143 #ifdef MAC
1144 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1145 if (error)
1146 return (error);
1147 #endif
1148 error = shm_access(map->sm_shmfd, ucred,
1149 FREAD | FWRITE);
1150 if (error)
1151 return (error);
1152 shm_doremove(map);
1153 return (0);
1154 }
1155 }
1156
1157 return (ENOENT);
1158 }
1159
1160 static void
shm_doremove(struct shm_mapping * map)1161 shm_doremove(struct shm_mapping *map)
1162 {
1163 map->sm_shmfd->shm_path = NULL;
1164 LIST_REMOVE(map, sm_link);
1165 shm_drop(map->sm_shmfd);
1166 free(map->sm_path, M_SHMFD);
1167 free(map, M_SHMFD);
1168 }
1169
1170 int
kern_shm_open2(struct thread * td,const char * userpath,int flags,mode_t mode,int shmflags,struct filecaps * fcaps,const char * name __unused)1171 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1172 int shmflags, struct filecaps *fcaps, const char *name __unused)
1173 {
1174 struct pwddesc *pdp;
1175 struct shmfd *shmfd;
1176 struct file *fp;
1177 char *path;
1178 void *rl_cookie;
1179 Fnv32_t fnv;
1180 mode_t cmode;
1181 int error, fd, initial_seals;
1182 bool largepage;
1183
1184 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1185 SHM_LARGEPAGE)) != 0)
1186 return (EINVAL);
1187
1188 initial_seals = F_SEAL_SEAL;
1189 if ((shmflags & SHM_ALLOW_SEALING) != 0)
1190 initial_seals &= ~F_SEAL_SEAL;
1191
1192 AUDIT_ARG_FFLAGS(flags);
1193 AUDIT_ARG_MODE(mode);
1194
1195 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1196 return (EINVAL);
1197
1198 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
1199 return (EINVAL);
1200
1201 largepage = (shmflags & SHM_LARGEPAGE) != 0;
1202 if (largepage && !PMAP_HAS_LARGEPAGES)
1203 return (ENOTTY);
1204
1205 /*
1206 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
1207 * If the decision is made later to allow additional seals, care must be
1208 * taken below to ensure that the seals are properly set if the shmfd
1209 * already existed -- this currently assumes that only F_SEAL_SEAL can
1210 * be set and doesn't take further precautions to ensure the validity of
1211 * the seals being added with respect to current mappings.
1212 */
1213 if ((initial_seals & ~F_SEAL_SEAL) != 0)
1214 return (EINVAL);
1215
1216 if (userpath != SHM_ANON) {
1217 error = shm_copyin_path(td, userpath, &path);
1218 if (error != 0)
1219 return (error);
1220
1221 #ifdef CAPABILITY_MODE
1222 /*
1223 * shm_open(2) is only allowed for anonymous objects.
1224 */
1225 if (CAP_TRACING(td))
1226 ktrcapfail(CAPFAIL_NAMEI, path);
1227 if (IN_CAPABILITY_MODE(td)) {
1228 error = ECAPMODE;
1229 goto outnofp;
1230 }
1231 #endif
1232
1233 AUDIT_ARG_UPATH1_CANON(path);
1234 } else {
1235 path = NULL;
1236 }
1237
1238 pdp = td->td_proc->p_pd;
1239 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1240
1241 /*
1242 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1243 * by POSIX. We allow it to be unset here so that an in-kernel
1244 * interface may be written as a thin layer around shm, optionally not
1245 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
1246 * in sys_shm_open() to keep this implementation compliant.
1247 */
1248 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1249 if (error != 0)
1250 goto outnofp;
1251
1252 /* A SHM_ANON path pointer creates an anonymous object. */
1253 if (userpath == SHM_ANON) {
1254 /* A read-only anonymous object is pointless. */
1255 if ((flags & O_ACCMODE) == O_RDONLY) {
1256 error = EINVAL;
1257 goto out;
1258 }
1259 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1260 if (shmfd == NULL) {
1261 error = ENOMEM;
1262 goto out;
1263 }
1264 shmfd->shm_seals = initial_seals;
1265 shmfd->shm_flags = shmflags;
1266 } else {
1267 fnv = fnv_32_str(path, FNV1_32_INIT);
1268 sx_xlock(&shm_dict_lock);
1269 shmfd = shm_lookup(path, fnv);
1270 if (shmfd == NULL) {
1271 /* Object does not yet exist, create it if requested. */
1272 if (flags & O_CREAT) {
1273 #ifdef MAC
1274 error = mac_posixshm_check_create(td->td_ucred,
1275 path);
1276 if (error == 0) {
1277 #endif
1278 shmfd = shm_alloc(td->td_ucred, cmode,
1279 largepage);
1280 if (shmfd == NULL) {
1281 error = ENOMEM;
1282 } else {
1283 shmfd->shm_seals =
1284 initial_seals;
1285 shmfd->shm_flags = shmflags;
1286 shm_insert(path, fnv, shmfd);
1287 path = NULL;
1288 }
1289 #ifdef MAC
1290 }
1291 #endif
1292 } else {
1293 error = ENOENT;
1294 }
1295 } else {
1296 /*
1297 * Object already exists, obtain a new reference if
1298 * requested and permitted.
1299 */
1300 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1301
1302 /*
1303 * kern_shm_open() likely shouldn't ever error out on
1304 * trying to set a seal that already exists, unlike
1305 * F_ADD_SEALS. This would break terribly as
1306 * shm_open(2) actually sets F_SEAL_SEAL to maintain
1307 * historical behavior where the underlying file could
1308 * not be sealed.
1309 */
1310 initial_seals &= ~shmfd->shm_seals;
1311
1312 /*
1313 * initial_seals can't set additional seals if we've
1314 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
1315 * then we've already removed that one from
1316 * initial_seals. This is currently redundant as we
1317 * only allow setting F_SEAL_SEAL at creation time, but
1318 * it's cheap to check and decreases the effort required
1319 * to allow additional seals.
1320 */
1321 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1322 initial_seals != 0)
1323 error = EPERM;
1324 else if ((flags & (O_CREAT | O_EXCL)) ==
1325 (O_CREAT | O_EXCL))
1326 error = EEXIST;
1327 else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1328 error = EINVAL;
1329 else {
1330 #ifdef MAC
1331 error = mac_posixshm_check_open(td->td_ucred,
1332 shmfd, FFLAGS(flags & O_ACCMODE));
1333 if (error == 0)
1334 #endif
1335 error = shm_access(shmfd, td->td_ucred,
1336 FFLAGS(flags & O_ACCMODE));
1337 }
1338
1339 /*
1340 * Truncate the file back to zero length if
1341 * O_TRUNC was specified and the object was
1342 * opened with read/write.
1343 */
1344 if (error == 0 &&
1345 (flags & (O_ACCMODE | O_TRUNC)) ==
1346 (O_RDWR | O_TRUNC)) {
1347 VM_OBJECT_WLOCK(shmfd->shm_object);
1348 #ifdef MAC
1349 error = mac_posixshm_check_truncate(
1350 td->td_ucred, fp->f_cred, shmfd);
1351 if (error == 0)
1352 #endif
1353 error = shm_dotruncate_locked(shmfd, 0,
1354 rl_cookie);
1355 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1356 }
1357 if (error == 0) {
1358 /*
1359 * Currently we only allow F_SEAL_SEAL to be
1360 * set initially. As noted above, this would
1361 * need to be reworked should that change.
1362 */
1363 shmfd->shm_seals |= initial_seals;
1364 shm_hold(shmfd);
1365 }
1366 shm_rangelock_unlock(shmfd, rl_cookie);
1367 }
1368 sx_xunlock(&shm_dict_lock);
1369
1370 if (error != 0)
1371 goto out;
1372 }
1373
1374 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1375
1376 td->td_retval[0] = fd;
1377 fdrop(fp, td);
1378 free(path, M_SHMFD);
1379
1380 return (0);
1381
1382 out:
1383 fdclose(td, fp, fd);
1384 fdrop(fp, td);
1385 outnofp:
1386 free(path, M_SHMFD);
1387
1388 return (error);
1389 }
1390
1391 /* System calls. */
1392 #ifdef COMPAT_FREEBSD12
1393 int
freebsd12_shm_open(struct thread * td,struct freebsd12_shm_open_args * uap)1394 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1395 {
1396
1397 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1398 uap->mode, NULL));
1399 }
1400 #endif
1401
1402 int
sys_shm_unlink(struct thread * td,struct shm_unlink_args * uap)1403 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1404 {
1405 char *path;
1406 Fnv32_t fnv;
1407 int error;
1408
1409 error = shm_copyin_path(td, uap->path, &path);
1410 if (error != 0)
1411 return (error);
1412
1413 AUDIT_ARG_UPATH1_CANON(path);
1414 fnv = fnv_32_str(path, FNV1_32_INIT);
1415 sx_xlock(&shm_dict_lock);
1416 error = shm_remove(path, fnv, td->td_ucred);
1417 sx_xunlock(&shm_dict_lock);
1418 free(path, M_SHMFD);
1419
1420 return (error);
1421 }
1422
1423 int
sys_shm_rename(struct thread * td,struct shm_rename_args * uap)1424 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1425 {
1426 char *path_from = NULL, *path_to = NULL;
1427 Fnv32_t fnv_from, fnv_to;
1428 struct shmfd *fd_from;
1429 struct shmfd *fd_to;
1430 int error;
1431 int flags;
1432
1433 flags = uap->flags;
1434 AUDIT_ARG_FFLAGS(flags);
1435
1436 /*
1437 * Make sure the user passed only valid flags.
1438 * If you add a new flag, please add a new term here.
1439 */
1440 if ((flags & ~(
1441 SHM_RENAME_NOREPLACE |
1442 SHM_RENAME_EXCHANGE
1443 )) != 0) {
1444 error = EINVAL;
1445 goto out;
1446 }
1447
1448 /*
1449 * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1450 * force the user to choose one or the other.
1451 */
1452 if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1453 (flags & SHM_RENAME_EXCHANGE) != 0) {
1454 error = EINVAL;
1455 goto out;
1456 }
1457
1458 /* Renaming to or from anonymous makes no sense */
1459 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1460 error = EINVAL;
1461 goto out;
1462 }
1463
1464 error = shm_copyin_path(td, uap->path_from, &path_from);
1465 if (error != 0)
1466 goto out;
1467
1468 error = shm_copyin_path(td, uap->path_to, &path_to);
1469 if (error != 0)
1470 goto out;
1471
1472 AUDIT_ARG_UPATH1_CANON(path_from);
1473 AUDIT_ARG_UPATH2_CANON(path_to);
1474
1475 /* Rename with from/to equal is a no-op */
1476 if (strcmp(path_from, path_to) == 0)
1477 goto out;
1478
1479 fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1480 fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1481
1482 sx_xlock(&shm_dict_lock);
1483
1484 fd_from = shm_lookup(path_from, fnv_from);
1485 if (fd_from == NULL) {
1486 error = ENOENT;
1487 goto out_locked;
1488 }
1489
1490 fd_to = shm_lookup(path_to, fnv_to);
1491 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1492 error = EEXIST;
1493 goto out_locked;
1494 }
1495
1496 /*
1497 * Unconditionally prevents shm_remove from invalidating the 'from'
1498 * shm's state.
1499 */
1500 shm_hold(fd_from);
1501 error = shm_remove(path_from, fnv_from, td->td_ucred);
1502
1503 /*
1504 * One of my assumptions failed if ENOENT (e.g. locking didn't
1505 * protect us)
1506 */
1507 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1508 path_from));
1509 if (error != 0) {
1510 shm_drop(fd_from);
1511 goto out_locked;
1512 }
1513
1514 /*
1515 * If we are exchanging, we need to ensure the shm_remove below
1516 * doesn't invalidate the dest shm's state.
1517 */
1518 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1519 shm_hold(fd_to);
1520
1521 /*
1522 * NOTE: if path_to is not already in the hash, c'est la vie;
1523 * it simply means we have nothing already at path_to to unlink.
1524 * That is the ENOENT case.
1525 *
1526 * If we somehow don't have access to unlink this guy, but
1527 * did for the shm at path_from, then relink the shm to path_from
1528 * and abort with EACCES.
1529 *
1530 * All other errors: that is weird; let's relink and abort the
1531 * operation.
1532 */
1533 error = shm_remove(path_to, fnv_to, td->td_ucred);
1534 if (error != 0 && error != ENOENT) {
1535 shm_insert(path_from, fnv_from, fd_from);
1536 shm_drop(fd_from);
1537 /* Don't free path_from now, since the hash references it */
1538 path_from = NULL;
1539 goto out_locked;
1540 }
1541
1542 error = 0;
1543
1544 shm_insert(path_to, fnv_to, fd_from);
1545
1546 /* Don't free path_to now, since the hash references it */
1547 path_to = NULL;
1548
1549 /* We kept a ref when we removed, and incremented again in insert */
1550 shm_drop(fd_from);
1551 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1552 fd_from->shm_refs));
1553
1554 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1555 shm_insert(path_from, fnv_from, fd_to);
1556 path_from = NULL;
1557 shm_drop(fd_to);
1558 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1559 fd_to->shm_refs));
1560 }
1561
1562 out_locked:
1563 sx_xunlock(&shm_dict_lock);
1564
1565 out:
1566 free(path_from, M_SHMFD);
1567 free(path_to, M_SHMFD);
1568 return (error);
1569 }
1570
1571 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)1572 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1573 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1574 vm_ooffset_t foff, struct thread *td)
1575 {
1576 struct vmspace *vms;
1577 vm_map_entry_t next_entry, prev_entry;
1578 vm_offset_t align, mask, maxaddr;
1579 int docow, error, rv, try;
1580 bool curmap;
1581
1582 if (shmfd->shm_lp_psind == 0)
1583 return (EINVAL);
1584
1585 /* MAP_PRIVATE is disabled */
1586 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1587 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0)
1588 return (EINVAL);
1589
1590 vms = td->td_proc->p_vmspace;
1591 curmap = map == &vms->vm_map;
1592 if (curmap) {
1593 error = kern_mmap_racct_check(td, map, size);
1594 if (error != 0)
1595 return (error);
1596 }
1597
1598 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1599 docow |= MAP_INHERIT_SHARE;
1600 if ((flags & MAP_NOCORE) != 0)
1601 docow |= MAP_DISABLE_COREDUMP;
1602
1603 mask = pagesizes[shmfd->shm_lp_psind] - 1;
1604 if ((foff & mask) != 0)
1605 return (EINVAL);
1606 maxaddr = vm_map_max(map);
1607 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1608 maxaddr = MAP_32BIT_MAX_ADDR;
1609 if (size == 0 || (size & mask) != 0 ||
1610 (*addr != 0 && ((*addr & mask) != 0 ||
1611 *addr + size < *addr || *addr + size > maxaddr)))
1612 return (EINVAL);
1613
1614 align = flags & MAP_ALIGNMENT_MASK;
1615 if (align == 0) {
1616 align = pagesizes[shmfd->shm_lp_psind];
1617 } else if (align == MAP_ALIGNED_SUPER) {
1618 if (shmfd->shm_lp_psind != 1)
1619 return (EINVAL);
1620 align = pagesizes[1];
1621 } else {
1622 align >>= MAP_ALIGNMENT_SHIFT;
1623 align = 1ULL << align;
1624 /* Also handles overflow. */
1625 if (align < pagesizes[shmfd->shm_lp_psind])
1626 return (EINVAL);
1627 }
1628
1629 vm_map_lock(map);
1630 if ((flags & MAP_FIXED) == 0) {
1631 try = 1;
1632 if (curmap && (*addr == 0 ||
1633 (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1634 *addr < round_page((vm_offset_t)vms->vm_daddr +
1635 lim_max(td, RLIMIT_DATA))))) {
1636 *addr = roundup2((vm_offset_t)vms->vm_daddr +
1637 lim_max(td, RLIMIT_DATA),
1638 pagesizes[shmfd->shm_lp_psind]);
1639 }
1640 again:
1641 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1642 if (rv != KERN_SUCCESS) {
1643 if (try == 1) {
1644 try = 2;
1645 *addr = vm_map_min(map);
1646 if ((*addr & mask) != 0)
1647 *addr = (*addr + mask) & mask;
1648 goto again;
1649 }
1650 goto fail1;
1651 }
1652 } else if ((flags & MAP_EXCL) == 0) {
1653 rv = vm_map_delete(map, *addr, *addr + size);
1654 if (rv != KERN_SUCCESS)
1655 goto fail1;
1656 } else {
1657 error = ENOSPC;
1658 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1659 goto fail;
1660 next_entry = vm_map_entry_succ(prev_entry);
1661 if (next_entry->start < *addr + size)
1662 goto fail;
1663 }
1664
1665 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1666 prot, max_prot, docow);
1667 fail1:
1668 error = vm_mmap_to_errno(rv);
1669 fail:
1670 vm_map_unlock(map);
1671 return (error);
1672 }
1673
1674 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)1675 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1676 vm_prot_t prot, vm_prot_t max_maxprot, int flags,
1677 vm_ooffset_t foff, struct thread *td)
1678 {
1679 struct shmfd *shmfd;
1680 vm_prot_t maxprot;
1681 int error;
1682 bool writecnt;
1683 void *rl_cookie;
1684
1685 shmfd = fp->f_data;
1686 maxprot = VM_PROT_NONE;
1687
1688 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize);
1689 /* FREAD should always be set. */
1690 if ((fp->f_flag & FREAD) != 0)
1691 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1692
1693 /*
1694 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1695 * mapping with a write seal applied. Private mappings are always
1696 * writeable.
1697 */
1698 if ((flags & MAP_SHARED) == 0) {
1699 if ((max_maxprot & VM_PROT_WRITE) != 0)
1700 maxprot |= VM_PROT_WRITE;
1701 writecnt = false;
1702 } else {
1703 if ((fp->f_flag & FWRITE) != 0 &&
1704 (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1705 maxprot |= VM_PROT_WRITE;
1706
1707 /*
1708 * Any mappings from a writable descriptor may be upgraded to
1709 * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1710 * applied between the open and subsequent mmap(2). We want to
1711 * reject application of a write seal as long as any such
1712 * mapping exists so that the seal cannot be trivially bypassed.
1713 */
1714 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1715 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1716 error = EACCES;
1717 goto out;
1718 }
1719 }
1720 maxprot &= max_maxprot;
1721
1722 /* See comment in vn_mmap(). */
1723 if (
1724 #ifdef _LP64
1725 objsize > OFF_MAX ||
1726 #endif
1727 foff > OFF_MAX - objsize) {
1728 error = EINVAL;
1729 goto out;
1730 }
1731
1732 #ifdef MAC
1733 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1734 if (error != 0)
1735 goto out;
1736 #endif
1737
1738 mtx_lock(&shm_timestamp_lock);
1739 vfs_timestamp(&shmfd->shm_atime);
1740 mtx_unlock(&shm_timestamp_lock);
1741 vm_object_reference(shmfd->shm_object);
1742
1743 if (shm_largepage(shmfd)) {
1744 writecnt = false;
1745 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1746 maxprot, flags, foff, td);
1747 } else {
1748 if (writecnt) {
1749 vm_pager_update_writecount(shmfd->shm_object, 0,
1750 objsize);
1751 }
1752 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1753 shmfd->shm_object, foff, writecnt, td);
1754 }
1755 if (error != 0) {
1756 if (writecnt)
1757 vm_pager_release_writecount(shmfd->shm_object, 0,
1758 objsize);
1759 vm_object_deallocate(shmfd->shm_object);
1760 }
1761 out:
1762 shm_rangelock_unlock(shmfd, rl_cookie);
1763 return (error);
1764 }
1765
1766 static int
shm_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1767 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1768 struct thread *td)
1769 {
1770 struct shmfd *shmfd;
1771 int error;
1772
1773 error = 0;
1774 shmfd = fp->f_data;
1775 mtx_lock(&shm_timestamp_lock);
1776 /*
1777 * SUSv4 says that x bits of permission need not be affected.
1778 * Be consistent with our shm_open there.
1779 */
1780 #ifdef MAC
1781 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1782 if (error != 0)
1783 goto out;
1784 #endif
1785 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1786 VADMIN, active_cred);
1787 if (error != 0)
1788 goto out;
1789 shmfd->shm_mode = mode & ACCESSPERMS;
1790 out:
1791 mtx_unlock(&shm_timestamp_lock);
1792 return (error);
1793 }
1794
1795 static int
shm_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1796 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1797 struct thread *td)
1798 {
1799 struct shmfd *shmfd;
1800 int error;
1801
1802 error = 0;
1803 shmfd = fp->f_data;
1804 mtx_lock(&shm_timestamp_lock);
1805 #ifdef MAC
1806 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1807 if (error != 0)
1808 goto out;
1809 #endif
1810 if (uid == (uid_t)-1)
1811 uid = shmfd->shm_uid;
1812 if (gid == (gid_t)-1)
1813 gid = shmfd->shm_gid;
1814 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1815 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1816 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1817 goto out;
1818 shmfd->shm_uid = uid;
1819 shmfd->shm_gid = gid;
1820 out:
1821 mtx_unlock(&shm_timestamp_lock);
1822 return (error);
1823 }
1824
1825 /*
1826 * Helper routines to allow the backing object of a shared memory file
1827 * descriptor to be mapped in the kernel.
1828 */
1829 int
shm_map(struct file * fp,size_t size,off_t offset,void ** memp)1830 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1831 {
1832 struct shmfd *shmfd;
1833 vm_offset_t kva, ofs;
1834 vm_object_t obj;
1835 int rv;
1836
1837 if (fp->f_type != DTYPE_SHM)
1838 return (EINVAL);
1839 shmfd = fp->f_data;
1840 obj = shmfd->shm_object;
1841 VM_OBJECT_WLOCK(obj);
1842 /*
1843 * XXXRW: This validation is probably insufficient, and subject to
1844 * sign errors. It should be fixed.
1845 */
1846 if (offset >= shmfd->shm_size ||
1847 offset + size > round_page(shmfd->shm_size)) {
1848 VM_OBJECT_WUNLOCK(obj);
1849 return (EINVAL);
1850 }
1851
1852 shmfd->shm_kmappings++;
1853 vm_object_reference_locked(obj);
1854 VM_OBJECT_WUNLOCK(obj);
1855
1856 /* Map the object into the kernel_map and wire it. */
1857 kva = vm_map_min(kernel_map);
1858 ofs = offset & PAGE_MASK;
1859 offset = trunc_page(offset);
1860 size = round_page(size + ofs);
1861 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1862 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1863 VM_PROT_READ | VM_PROT_WRITE, 0);
1864 if (rv == KERN_SUCCESS) {
1865 rv = vm_map_wire(kernel_map, kva, kva + size,
1866 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1867 if (rv == KERN_SUCCESS) {
1868 *memp = (void *)(kva + ofs);
1869 return (0);
1870 }
1871 vm_map_remove(kernel_map, kva, kva + size);
1872 } else
1873 vm_object_deallocate(obj);
1874
1875 /* On failure, drop our mapping reference. */
1876 VM_OBJECT_WLOCK(obj);
1877 shmfd->shm_kmappings--;
1878 VM_OBJECT_WUNLOCK(obj);
1879
1880 return (vm_mmap_to_errno(rv));
1881 }
1882
1883 /*
1884 * We require the caller to unmap the entire entry. This allows us to
1885 * safely decrement shm_kmappings when a mapping is removed.
1886 */
1887 int
shm_unmap(struct file * fp,void * mem,size_t size)1888 shm_unmap(struct file *fp, void *mem, size_t size)
1889 {
1890 struct shmfd *shmfd;
1891 vm_map_entry_t entry;
1892 vm_offset_t kva, ofs;
1893 vm_object_t obj;
1894 vm_pindex_t pindex;
1895 vm_prot_t prot;
1896 boolean_t wired;
1897 vm_map_t map;
1898 int rv;
1899
1900 if (fp->f_type != DTYPE_SHM)
1901 return (EINVAL);
1902 shmfd = fp->f_data;
1903 kva = (vm_offset_t)mem;
1904 ofs = kva & PAGE_MASK;
1905 kva = trunc_page(kva);
1906 size = round_page(size + ofs);
1907 map = kernel_map;
1908 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1909 &obj, &pindex, &prot, &wired);
1910 if (rv != KERN_SUCCESS)
1911 return (EINVAL);
1912 if (entry->start != kva || entry->end != kva + size) {
1913 vm_map_lookup_done(map, entry);
1914 return (EINVAL);
1915 }
1916 vm_map_lookup_done(map, entry);
1917 if (obj != shmfd->shm_object)
1918 return (EINVAL);
1919 vm_map_remove(map, kva, kva + size);
1920 VM_OBJECT_WLOCK(obj);
1921 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1922 shmfd->shm_kmappings--;
1923 VM_OBJECT_WUNLOCK(obj);
1924 return (0);
1925 }
1926
1927 static int
shm_fill_kinfo_locked(struct shmfd * shmfd,struct kinfo_file * kif,bool list)1928 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1929 {
1930 const char *path, *pr_path;
1931 size_t pr_pathlen;
1932 bool visible;
1933
1934 sx_assert(&shm_dict_lock, SA_LOCKED);
1935 kif->kf_type = KF_TYPE_SHM;
1936 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1937 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1938 if (shmfd->shm_path != NULL) {
1939 path = shmfd->shm_path;
1940 pr_path = curthread->td_ucred->cr_prison->pr_path;
1941 if (strcmp(pr_path, "/") != 0) {
1942 /* Return the jail-rooted pathname. */
1943 pr_pathlen = strlen(pr_path);
1944 visible = strncmp(path, pr_path, pr_pathlen) == 0 &&
1945 path[pr_pathlen] == '/';
1946 if (list && !visible)
1947 return (EPERM);
1948 if (visible)
1949 path += pr_pathlen;
1950 }
1951 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1952 }
1953 return (0);
1954 }
1955
1956 static int
shm_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp __unused)1957 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1958 struct filedesc *fdp __unused)
1959 {
1960 int res;
1961
1962 sx_slock(&shm_dict_lock);
1963 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1964 sx_sunlock(&shm_dict_lock);
1965 return (res);
1966 }
1967
1968 static int
shm_add_seals(struct file * fp,int seals)1969 shm_add_seals(struct file *fp, int seals)
1970 {
1971 struct shmfd *shmfd;
1972 void *rl_cookie;
1973 vm_ooffset_t writemappings;
1974 int error, nseals;
1975
1976 error = 0;
1977 shmfd = fp->f_data;
1978 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1979
1980 /* Even already-set seals should result in EPERM. */
1981 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
1982 error = EPERM;
1983 goto out;
1984 }
1985 nseals = seals & ~shmfd->shm_seals;
1986 if ((nseals & F_SEAL_WRITE) != 0) {
1987 if (shm_largepage(shmfd)) {
1988 error = ENOTSUP;
1989 goto out;
1990 }
1991
1992 /*
1993 * The rangelock above prevents writable mappings from being
1994 * added after we've started applying seals. The RLOCK here
1995 * is to avoid torn reads on ILP32 arches as unmapping/reducing
1996 * writemappings will be done without a rangelock.
1997 */
1998 VM_OBJECT_RLOCK(shmfd->shm_object);
1999 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
2000 VM_OBJECT_RUNLOCK(shmfd->shm_object);
2001 /* kmappings are also writable */
2002 if (writemappings > 0) {
2003 error = EBUSY;
2004 goto out;
2005 }
2006 }
2007 shmfd->shm_seals |= nseals;
2008 out:
2009 shm_rangelock_unlock(shmfd, rl_cookie);
2010 return (error);
2011 }
2012
2013 static int
shm_get_seals(struct file * fp,int * seals)2014 shm_get_seals(struct file *fp, int *seals)
2015 {
2016 struct shmfd *shmfd;
2017
2018 shmfd = fp->f_data;
2019 *seals = shmfd->shm_seals;
2020 return (0);
2021 }
2022
2023 static int
shm_deallocate(struct shmfd * shmfd,off_t * offset,off_t * length,int flags)2024 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
2025 {
2026 vm_object_t object;
2027 vm_pindex_t pistart, pi, piend;
2028 vm_ooffset_t off, len;
2029 int startofs, endofs, end;
2030 int error;
2031
2032 off = *offset;
2033 len = *length;
2034 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
2035 if (off + len > shmfd->shm_size)
2036 len = shmfd->shm_size - off;
2037 object = shmfd->shm_object;
2038 startofs = off & PAGE_MASK;
2039 endofs = (off + len) & PAGE_MASK;
2040 pistart = OFF_TO_IDX(off);
2041 piend = OFF_TO_IDX(off + len);
2042 pi = OFF_TO_IDX(off + PAGE_MASK);
2043 error = 0;
2044
2045 /* Handle the case when offset is on or beyond shm size. */
2046 if ((off_t)len <= 0) {
2047 *length = 0;
2048 return (0);
2049 }
2050
2051 VM_OBJECT_WLOCK(object);
2052
2053 if (startofs != 0) {
2054 end = pistart != piend ? PAGE_SIZE : endofs;
2055 error = shm_partial_page_invalidate(object, pistart, startofs,
2056 end);
2057 if (error)
2058 goto out;
2059 off += end - startofs;
2060 len -= end - startofs;
2061 }
2062
2063 if (pi < piend) {
2064 vm_object_page_remove(object, pi, piend, 0);
2065 off += IDX_TO_OFF(piend - pi);
2066 len -= IDX_TO_OFF(piend - pi);
2067 }
2068
2069 if (endofs != 0 && pistart != piend) {
2070 error = shm_partial_page_invalidate(object, piend, 0, endofs);
2071 if (error)
2072 goto out;
2073 off += endofs;
2074 len -= endofs;
2075 }
2076
2077 out:
2078 VM_OBJECT_WUNLOCK(shmfd->shm_object);
2079 *offset = off;
2080 *length = len;
2081 return (error);
2082 }
2083
2084 static int
shm_fspacectl(struct file * fp,int cmd,off_t * offset,off_t * length,int flags,struct ucred * active_cred,struct thread * td)2085 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
2086 struct ucred *active_cred, struct thread *td)
2087 {
2088 void *rl_cookie;
2089 struct shmfd *shmfd;
2090 off_t off, len;
2091 int error;
2092
2093 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
2094 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
2095 ("shm_fspacectl: non-zero flags"));
2096 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
2097 ("shm_fspacectl: offset/length overflow or underflow"));
2098 error = EINVAL;
2099 shmfd = fp->f_data;
2100 off = *offset;
2101 len = *length;
2102
2103 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len);
2104 switch (cmd) {
2105 case SPACECTL_DEALLOC:
2106 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2107 error = EPERM;
2108 break;
2109 }
2110 error = shm_deallocate(shmfd, &off, &len, flags);
2111 *offset = off;
2112 *length = len;
2113 break;
2114 default:
2115 __assert_unreachable();
2116 }
2117 shm_rangelock_unlock(shmfd, rl_cookie);
2118 return (error);
2119 }
2120
2121
2122 static int
shm_fallocate(struct file * fp,off_t offset,off_t len,struct thread * td)2123 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2124 {
2125 void *rl_cookie;
2126 struct shmfd *shmfd;
2127 size_t size;
2128 int error;
2129
2130 /* This assumes that the caller already checked for overflow. */
2131 error = 0;
2132 shmfd = fp->f_data;
2133 size = offset + len;
2134
2135 /*
2136 * Just grab the rangelock for the range that we may be attempting to
2137 * grow, rather than blocking read/write for regions we won't be
2138 * touching while this (potential) resize is in progress. Other
2139 * attempts to resize the shmfd will have to take a write lock from 0 to
2140 * OFF_MAX, so this being potentially beyond the current usable range of
2141 * the shmfd is not necessarily a concern. If other mechanisms are
2142 * added to grow a shmfd, this may need to be re-evaluated.
2143 */
2144 rl_cookie = shm_rangelock_wlock(shmfd, offset, size);
2145 if (size > shmfd->shm_size)
2146 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2147 shm_rangelock_unlock(shmfd, rl_cookie);
2148 /* Translate to posix_fallocate(2) return value as needed. */
2149 if (error == ENOMEM)
2150 error = ENOSPC;
2151 return (error);
2152 }
2153
2154 static int
sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)2155 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2156 {
2157 struct shm_mapping *shmm;
2158 struct sbuf sb;
2159 struct kinfo_file kif;
2160 u_long i;
2161 int error, error2;
2162
2163 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2164 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2165 error = 0;
2166 sx_slock(&shm_dict_lock);
2167 for (i = 0; i < shm_hash + 1; i++) {
2168 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2169 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2170 &kif, true);
2171 if (error == EPERM) {
2172 error = 0;
2173 continue;
2174 }
2175 if (error != 0)
2176 break;
2177 pack_kinfo(&kif);
2178 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2179 0 : ENOMEM;
2180 if (error != 0)
2181 break;
2182 }
2183 }
2184 sx_sunlock(&shm_dict_lock);
2185 error2 = sbuf_finish(&sb);
2186 sbuf_delete(&sb);
2187 return (error != 0 ? error : error2);
2188 }
2189
2190 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2191 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2192 NULL, 0, sysctl_posix_shm_list, "",
2193 "POSIX SHM list");
2194
2195 int
kern_shm_open(struct thread * td,const char * path,int flags,mode_t mode,struct filecaps * caps)2196 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2197 struct filecaps *caps)
2198 {
2199
2200 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
2201 }
2202
2203 /*
2204 * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2205 * caller, and libc will enforce it for the traditional shm_open() call. This
2206 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
2207 * interface also includes a 'name' argument that is currently unused, but could
2208 * potentially be exported later via some interface for debugging purposes.
2209 * From the kernel's perspective, it is optional. Individual consumers like
2210 * memfd_create() may require it in order to be compatible with other systems
2211 * implementing the same function.
2212 */
2213 int
sys_shm_open2(struct thread * td,struct shm_open2_args * uap)2214 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2215 {
2216
2217 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2218 uap->shmflags, NULL, uap->name));
2219 }
2220
2221 int
shm_get_path(struct vm_object * obj,char * path,size_t sz)2222 shm_get_path(struct vm_object *obj, char *path, size_t sz)
2223 {
2224 struct shmfd *shmfd;
2225 int error;
2226
2227 error = 0;
2228 shmfd = NULL;
2229 sx_slock(&shm_dict_lock);
2230 VM_OBJECT_RLOCK(obj);
2231 if ((obj->flags & OBJ_POSIXSHM) == 0) {
2232 error = EINVAL;
2233 } else {
2234 if (obj->type == shmfd_pager_type)
2235 shmfd = obj->un_pager.swp.swp_priv;
2236 else if (obj->type == OBJT_PHYS)
2237 shmfd = obj->un_pager.phys.phys_priv;
2238 if (shmfd == NULL) {
2239 error = ENXIO;
2240 } else {
2241 strlcpy(path, shmfd->shm_path == NULL ? "anon" :
2242 shmfd->shm_path, sz);
2243 }
2244 }
2245 if (error != 0)
2246 path[0] = '\0';
2247 VM_OBJECT_RUNLOCK(obj);
2248 sx_sunlock(&shm_dict_lock);
2249 return (error);
2250 }
2251