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))
188 #define shm_rangelock_rlock(shmfd, start, end) \
189 rangelock_rlock(&(shmfd)->shm_rl, (start), (end))
190 #define shm_rangelock_tryrlock(shmfd, start, end) \
191 rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end))
192 #define shm_rangelock_wlock(shmfd, start, end) \
193 rangelock_wlock(&(shmfd)->shm_rl, (start), (end))
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 int error;
706
707 error = vm_page_grab_zero_partial(object, idx, base, end);
708 if (error == EIO)
709 VM_OBJECT_WUNLOCK(object);
710 return (error);
711 }
712
713 static int
shm_dotruncate_locked(struct shmfd * shmfd,off_t length,void * rl_cookie)714 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie)
715 {
716 vm_object_t object;
717 vm_pindex_t nobjsize;
718 vm_ooffset_t delta;
719 int base, error;
720
721 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
722 object = shmfd->shm_object;
723 VM_OBJECT_ASSERT_WLOCKED(object);
724 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
725 if (length == shmfd->shm_size)
726 return (0);
727 nobjsize = OFF_TO_IDX(length + PAGE_MASK);
728
729 /* Are we shrinking? If so, trim the end. */
730 if (length < shmfd->shm_size) {
731 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
732 return (EPERM);
733
734 /*
735 * Disallow any requests to shrink the size if this
736 * object is mapped into the kernel.
737 */
738 if (shmfd->shm_kmappings > 0)
739 return (EBUSY);
740
741 /*
742 * Zero the truncated part of the last page.
743 */
744 base = length & PAGE_MASK;
745 if (base != 0) {
746 error = shm_partial_page_invalidate(object,
747 OFF_TO_IDX(length), base, PAGE_SIZE);
748 if (error)
749 return (error);
750 }
751 delta = IDX_TO_OFF(object->size - nobjsize);
752
753 if (nobjsize < object->size)
754 vm_object_page_remove(object, nobjsize, object->size,
755 0);
756
757 /* Free the swap accounted for shm */
758 swap_release_by_cred(delta, object->cred);
759 object->charge -= delta;
760 } else {
761 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
762 return (EPERM);
763
764 /* Try to reserve additional swap space. */
765 delta = IDX_TO_OFF(nobjsize - object->size);
766 if (!swap_reserve_by_cred(delta, object->cred))
767 return (ENOMEM);
768 object->charge += delta;
769 }
770 shmfd->shm_size = length;
771 mtx_lock(&shm_timestamp_lock);
772 vfs_timestamp(&shmfd->shm_ctime);
773 shmfd->shm_mtime = shmfd->shm_ctime;
774 mtx_unlock(&shm_timestamp_lock);
775 object->size = nobjsize;
776 return (0);
777 }
778
779 static int
shm_dotruncate_largepage(struct shmfd * shmfd,off_t length,void * rl_cookie)780 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie)
781 {
782 vm_object_t object;
783 vm_page_t m;
784 vm_pindex_t newobjsz;
785 vm_pindex_t oldobjsz __unused;
786 int aflags, error, i, psind, try;
787
788 KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
789 object = shmfd->shm_object;
790 VM_OBJECT_ASSERT_WLOCKED(object);
791 rangelock_cookie_assert(rl_cookie, RA_WLOCKED);
792
793 oldobjsz = object->size;
794 newobjsz = OFF_TO_IDX(length);
795 if (length == shmfd->shm_size)
796 return (0);
797 psind = shmfd->shm_lp_psind;
798 if (psind == 0 && length != 0)
799 return (EINVAL);
800 if ((length & (pagesizes[psind] - 1)) != 0)
801 return (EINVAL);
802
803 if (length < shmfd->shm_size) {
804 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0)
805 return (EPERM);
806 if (shmfd->shm_kmappings > 0)
807 return (EBUSY);
808 return (ENOTSUP); /* Pages are unmanaged. */
809 #if 0
810 vm_object_page_remove(object, newobjsz, oldobjsz, 0);
811 object->size = newobjsz;
812 shmfd->shm_size = length;
813 return (0);
814 #endif
815 }
816
817 if ((shmfd->shm_seals & F_SEAL_GROW) != 0)
818 return (EPERM);
819
820 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO;
821 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT)
822 aflags |= VM_ALLOC_WAITFAIL;
823 try = 0;
824
825 /*
826 * Extend shmfd and object, keeping all already fully
827 * allocated large pages intact even on error, because dropped
828 * object lock might allowed mapping of them.
829 */
830 while (object->size < newobjsz) {
831 m = vm_page_alloc_contig(object, object->size, aflags,
832 pagesizes[psind] / PAGE_SIZE, 0, ~0,
833 pagesizes[psind], 0,
834 VM_MEMATTR_DEFAULT);
835 if (m == NULL) {
836 VM_OBJECT_WUNLOCK(object);
837 if (shmfd->shm_lp_alloc_policy ==
838 SHM_LARGEPAGE_ALLOC_NOWAIT ||
839 (shmfd->shm_lp_alloc_policy ==
840 SHM_LARGEPAGE_ALLOC_DEFAULT &&
841 try >= largepage_reclaim_tries)) {
842 VM_OBJECT_WLOCK(object);
843 return (ENOMEM);
844 }
845 error = vm_page_reclaim_contig(aflags,
846 pagesizes[psind] / PAGE_SIZE, 0, ~0,
847 pagesizes[psind], 0);
848 if (error == ENOMEM)
849 error = vm_wait_intr(object);
850 if (error != 0) {
851 VM_OBJECT_WLOCK(object);
852 return (error);
853 }
854 try++;
855 VM_OBJECT_WLOCK(object);
856 continue;
857 }
858 try = 0;
859 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) {
860 if ((m[i].flags & PG_ZERO) == 0)
861 pmap_zero_page(&m[i]);
862 vm_page_valid(&m[i]);
863 vm_page_xunbusy(&m[i]);
864 }
865 object->size += OFF_TO_IDX(pagesizes[psind]);
866 shmfd->shm_size += pagesizes[psind];
867 atomic_add_long(&count_largepages[psind], 1);
868 vm_wire_add(atop(pagesizes[psind]));
869 }
870 return (0);
871 }
872
873 static int
shm_dotruncate_cookie(struct shmfd * shmfd,off_t length,void * rl_cookie)874 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie)
875 {
876 int error;
877
878 VM_OBJECT_WLOCK(shmfd->shm_object);
879 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd,
880 length, rl_cookie) : shm_dotruncate_locked(shmfd, length,
881 rl_cookie);
882 VM_OBJECT_WUNLOCK(shmfd->shm_object);
883 return (error);
884 }
885
886 int
shm_dotruncate(struct shmfd * shmfd,off_t length)887 shm_dotruncate(struct shmfd *shmfd, off_t length)
888 {
889 void *rl_cookie;
890 int error;
891
892 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
893 error = shm_dotruncate_cookie(shmfd, length, rl_cookie);
894 shm_rangelock_unlock(shmfd, rl_cookie);
895 return (error);
896 }
897
898 /*
899 * shmfd object management including creation and reference counting
900 * routines.
901 */
902 struct shmfd *
shm_alloc(struct ucred * ucred,mode_t mode,bool largepage)903 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage)
904 {
905 struct shmfd *shmfd;
906 vm_object_t obj;
907
908 if (largepage) {
909 obj = phys_pager_allocate(NULL, &shm_largepage_phys_ops,
910 NULL, 0, VM_PROT_DEFAULT, 0, ucred);
911 } else {
912 obj = vm_pager_allocate(shmfd_pager_type, NULL, 0,
913 VM_PROT_DEFAULT, 0, ucred);
914 }
915 if (obj == NULL) {
916 /*
917 * swap reservation limits can cause object allocation
918 * to fail.
919 */
920 return (NULL);
921 }
922
923 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
924 shmfd->shm_uid = ucred->cr_uid;
925 shmfd->shm_gid = ucred->cr_gid;
926 shmfd->shm_mode = mode;
927 if (largepage) {
928 obj->un_pager.phys.phys_priv = shmfd;
929 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT;
930 } else {
931 obj->un_pager.swp.swp_priv = shmfd;
932 }
933
934 VM_OBJECT_WLOCK(obj);
935 vm_object_set_flag(obj, OBJ_POSIXSHM);
936 VM_OBJECT_WUNLOCK(obj);
937 shmfd->shm_object = obj;
938 vfs_timestamp(&shmfd->shm_birthtime);
939 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
940 shmfd->shm_birthtime;
941 shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
942 refcount_init(&shmfd->shm_refs, 1);
943 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
944 rangelock_init(&shmfd->shm_rl);
945 #ifdef MAC
946 mac_posixshm_init(shmfd);
947 mac_posixshm_create(ucred, shmfd);
948 #endif
949
950 return (shmfd);
951 }
952
953 struct shmfd *
shm_hold(struct shmfd * shmfd)954 shm_hold(struct shmfd *shmfd)
955 {
956
957 refcount_acquire(&shmfd->shm_refs);
958 return (shmfd);
959 }
960
961 void
shm_drop(struct shmfd * shmfd)962 shm_drop(struct shmfd *shmfd)
963 {
964 vm_object_t obj;
965
966 if (refcount_release(&shmfd->shm_refs)) {
967 #ifdef MAC
968 mac_posixshm_destroy(shmfd);
969 #endif
970 rangelock_destroy(&shmfd->shm_rl);
971 mtx_destroy(&shmfd->shm_mtx);
972 obj = shmfd->shm_object;
973 VM_OBJECT_WLOCK(obj);
974 if (shm_largepage(shmfd))
975 obj->un_pager.phys.phys_priv = NULL;
976 else
977 obj->un_pager.swp.swp_priv = NULL;
978 VM_OBJECT_WUNLOCK(obj);
979 vm_object_deallocate(obj);
980 free(shmfd, M_SHMFD);
981 }
982 }
983
984 /*
985 * Determine if the credentials have sufficient permissions for a
986 * specified combination of FREAD and FWRITE.
987 */
988 int
shm_access(struct shmfd * shmfd,struct ucred * ucred,int flags)989 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
990 {
991 accmode_t accmode;
992 int error;
993
994 accmode = 0;
995 if (flags & FREAD)
996 accmode |= VREAD;
997 if (flags & FWRITE)
998 accmode |= VWRITE;
999 mtx_lock(&shm_timestamp_lock);
1000 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1001 accmode, ucred);
1002 mtx_unlock(&shm_timestamp_lock);
1003 return (error);
1004 }
1005
1006 static void
shm_init(void * arg)1007 shm_init(void *arg)
1008 {
1009 char name[32];
1010 int i;
1011
1012 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
1013 sx_init(&shm_dict_lock, "shm dictionary");
1014 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
1015 new_unrhdr64(&shm_ino_unr, 1);
1016 shm_dev_ino = devfs_alloc_cdp_inode();
1017 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
1018 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops,
1019 OBJT_SWAP);
1020 MPASS(shmfd_pager_type != -1);
1021
1022 for (i = 1; i < MAXPAGESIZES; i++) {
1023 if (pagesizes[i] == 0)
1024 break;
1025 #define M (1024 * 1024)
1026 #define G (1024 * M)
1027 if (pagesizes[i] >= G)
1028 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G);
1029 else if (pagesizes[i] >= M)
1030 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M);
1031 else
1032 snprintf(name, sizeof(name), "%lu", pagesizes[i]);
1033 #undef G
1034 #undef M
1035 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages),
1036 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i],
1037 "number of non-transient largepages allocated");
1038 }
1039 }
1040 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
1041
1042 /*
1043 * Remove all shared memory objects that belong to a prison.
1044 */
1045 void
shm_remove_prison(struct prison * pr)1046 shm_remove_prison(struct prison *pr)
1047 {
1048 struct shm_mapping *shmm, *tshmm;
1049 u_long i;
1050
1051 sx_xlock(&shm_dict_lock);
1052 for (i = 0; i < shm_hash + 1; i++) {
1053 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) {
1054 if (shmm->sm_shmfd->shm_object->cred &&
1055 shmm->sm_shmfd->shm_object->cred->cr_prison == pr)
1056 shm_doremove(shmm);
1057 }
1058 }
1059 sx_xunlock(&shm_dict_lock);
1060 }
1061
1062 /*
1063 * Dictionary management. We maintain an in-kernel dictionary to map
1064 * paths to shmfd objects. We use the FNV hash on the path to store
1065 * the mappings in a hash table.
1066 */
1067 static struct shmfd *
shm_lookup(char * path,Fnv32_t fnv)1068 shm_lookup(char *path, Fnv32_t fnv)
1069 {
1070 struct shm_mapping *map;
1071
1072 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1073 if (map->sm_fnv != fnv)
1074 continue;
1075 if (strcmp(map->sm_path, path) == 0)
1076 return (map->sm_shmfd);
1077 }
1078
1079 return (NULL);
1080 }
1081
1082 static void
shm_insert(char * path,Fnv32_t fnv,struct shmfd * shmfd)1083 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
1084 {
1085 struct shm_mapping *map;
1086
1087 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
1088 map->sm_path = path;
1089 map->sm_fnv = fnv;
1090 map->sm_shmfd = shm_hold(shmfd);
1091 shmfd->shm_path = path;
1092 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
1093 }
1094
1095 static int
shm_remove(char * path,Fnv32_t fnv,struct ucred * ucred)1096 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
1097 {
1098 struct shm_mapping *map;
1099 int error;
1100
1101 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
1102 if (map->sm_fnv != fnv)
1103 continue;
1104 if (strcmp(map->sm_path, path) == 0) {
1105 #ifdef MAC
1106 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
1107 if (error)
1108 return (error);
1109 #endif
1110 error = shm_access(map->sm_shmfd, ucred,
1111 FREAD | FWRITE);
1112 if (error)
1113 return (error);
1114 shm_doremove(map);
1115 return (0);
1116 }
1117 }
1118
1119 return (ENOENT);
1120 }
1121
1122 static void
shm_doremove(struct shm_mapping * map)1123 shm_doremove(struct shm_mapping *map)
1124 {
1125 map->sm_shmfd->shm_path = NULL;
1126 LIST_REMOVE(map, sm_link);
1127 shm_drop(map->sm_shmfd);
1128 free(map->sm_path, M_SHMFD);
1129 free(map, M_SHMFD);
1130 }
1131
1132 int
kern_shm_open2(struct thread * td,const char * userpath,int flags,mode_t mode,int shmflags,struct filecaps * fcaps,const char * name __unused)1133 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode,
1134 int shmflags, struct filecaps *fcaps, const char *name __unused)
1135 {
1136 struct pwddesc *pdp;
1137 struct shmfd *shmfd;
1138 struct file *fp;
1139 char *path;
1140 void *rl_cookie;
1141 Fnv32_t fnv;
1142 mode_t cmode;
1143 int error, fd, initial_seals;
1144 bool largepage;
1145
1146 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE |
1147 SHM_LARGEPAGE)) != 0)
1148 return (EINVAL);
1149
1150 initial_seals = F_SEAL_SEAL;
1151 if ((shmflags & SHM_ALLOW_SEALING) != 0)
1152 initial_seals &= ~F_SEAL_SEAL;
1153
1154 AUDIT_ARG_FFLAGS(flags);
1155 AUDIT_ARG_MODE(mode);
1156
1157 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
1158 return (EINVAL);
1159
1160 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
1161 return (EINVAL);
1162
1163 largepage = (shmflags & SHM_LARGEPAGE) != 0;
1164 if (largepage && !PMAP_HAS_LARGEPAGES)
1165 return (ENOTTY);
1166
1167 /*
1168 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd.
1169 * If the decision is made later to allow additional seals, care must be
1170 * taken below to ensure that the seals are properly set if the shmfd
1171 * already existed -- this currently assumes that only F_SEAL_SEAL can
1172 * be set and doesn't take further precautions to ensure the validity of
1173 * the seals being added with respect to current mappings.
1174 */
1175 if ((initial_seals & ~F_SEAL_SEAL) != 0)
1176 return (EINVAL);
1177
1178 if (userpath != SHM_ANON) {
1179 error = shm_copyin_path(td, userpath, &path);
1180 if (error != 0)
1181 return (error);
1182
1183 #ifdef CAPABILITY_MODE
1184 /*
1185 * shm_open(2) is only allowed for anonymous objects.
1186 */
1187 if (CAP_TRACING(td))
1188 ktrcapfail(CAPFAIL_NAMEI, path);
1189 if (IN_CAPABILITY_MODE(td)) {
1190 error = ECAPMODE;
1191 goto outnofp;
1192 }
1193 #endif
1194
1195 AUDIT_ARG_UPATH1_CANON(path);
1196 } else {
1197 path = NULL;
1198 }
1199
1200 pdp = td->td_proc->p_pd;
1201 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS;
1202
1203 /*
1204 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated
1205 * by POSIX. We allow it to be unset here so that an in-kernel
1206 * interface may be written as a thin layer around shm, optionally not
1207 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally
1208 * in sys_shm_open() to keep this implementation compliant.
1209 */
1210 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps);
1211 if (error != 0)
1212 goto outnofp;
1213
1214 /* A SHM_ANON path pointer creates an anonymous object. */
1215 if (userpath == SHM_ANON) {
1216 /* A read-only anonymous object is pointless. */
1217 if ((flags & O_ACCMODE) == O_RDONLY) {
1218 error = EINVAL;
1219 goto out;
1220 }
1221 shmfd = shm_alloc(td->td_ucred, cmode, largepage);
1222 if (shmfd == NULL) {
1223 error = ENOMEM;
1224 goto out;
1225 }
1226 shmfd->shm_seals = initial_seals;
1227 shmfd->shm_flags = shmflags;
1228 } else {
1229 fnv = fnv_32_str(path, FNV1_32_INIT);
1230 sx_xlock(&shm_dict_lock);
1231 shmfd = shm_lookup(path, fnv);
1232 if (shmfd == NULL) {
1233 /* Object does not yet exist, create it if requested. */
1234 if (flags & O_CREAT) {
1235 #ifdef MAC
1236 error = mac_posixshm_check_create(td->td_ucred,
1237 path);
1238 if (error == 0) {
1239 #endif
1240 shmfd = shm_alloc(td->td_ucred, cmode,
1241 largepage);
1242 if (shmfd == NULL) {
1243 error = ENOMEM;
1244 } else {
1245 shmfd->shm_seals =
1246 initial_seals;
1247 shmfd->shm_flags = shmflags;
1248 shm_insert(path, fnv, shmfd);
1249 path = NULL;
1250 }
1251 #ifdef MAC
1252 }
1253 #endif
1254 } else {
1255 error = ENOENT;
1256 }
1257 } else {
1258 /*
1259 * Object already exists, obtain a new reference if
1260 * requested and permitted.
1261 */
1262 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1263
1264 /*
1265 * kern_shm_open() likely shouldn't ever error out on
1266 * trying to set a seal that already exists, unlike
1267 * F_ADD_SEALS. This would break terribly as
1268 * shm_open(2) actually sets F_SEAL_SEAL to maintain
1269 * historical behavior where the underlying file could
1270 * not be sealed.
1271 */
1272 initial_seals &= ~shmfd->shm_seals;
1273
1274 /*
1275 * initial_seals can't set additional seals if we've
1276 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set,
1277 * then we've already removed that one from
1278 * initial_seals. This is currently redundant as we
1279 * only allow setting F_SEAL_SEAL at creation time, but
1280 * it's cheap to check and decreases the effort required
1281 * to allow additional seals.
1282 */
1283 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 &&
1284 initial_seals != 0)
1285 error = EPERM;
1286 else if ((flags & (O_CREAT | O_EXCL)) ==
1287 (O_CREAT | O_EXCL))
1288 error = EEXIST;
1289 else if (shmflags != 0 && shmflags != shmfd->shm_flags)
1290 error = EINVAL;
1291 else {
1292 #ifdef MAC
1293 error = mac_posixshm_check_open(td->td_ucred,
1294 shmfd, FFLAGS(flags & O_ACCMODE));
1295 if (error == 0)
1296 #endif
1297 error = shm_access(shmfd, td->td_ucred,
1298 FFLAGS(flags & O_ACCMODE));
1299 }
1300
1301 /*
1302 * Truncate the file back to zero length if
1303 * O_TRUNC was specified and the object was
1304 * opened with read/write.
1305 */
1306 if (error == 0 &&
1307 (flags & (O_ACCMODE | O_TRUNC)) ==
1308 (O_RDWR | O_TRUNC)) {
1309 VM_OBJECT_WLOCK(shmfd->shm_object);
1310 #ifdef MAC
1311 error = mac_posixshm_check_truncate(
1312 td->td_ucred, fp->f_cred, shmfd);
1313 if (error == 0)
1314 #endif
1315 error = shm_dotruncate_locked(shmfd, 0,
1316 rl_cookie);
1317 VM_OBJECT_WUNLOCK(shmfd->shm_object);
1318 }
1319 if (error == 0) {
1320 /*
1321 * Currently we only allow F_SEAL_SEAL to be
1322 * set initially. As noted above, this would
1323 * need to be reworked should that change.
1324 */
1325 shmfd->shm_seals |= initial_seals;
1326 shm_hold(shmfd);
1327 }
1328 shm_rangelock_unlock(shmfd, rl_cookie);
1329 }
1330 sx_xunlock(&shm_dict_lock);
1331
1332 if (error != 0)
1333 goto out;
1334 }
1335
1336 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
1337
1338 td->td_retval[0] = fd;
1339 fdrop(fp, td);
1340 free(path, M_SHMFD);
1341
1342 return (0);
1343
1344 out:
1345 fdclose(td, fp, fd);
1346 fdrop(fp, td);
1347 outnofp:
1348 free(path, M_SHMFD);
1349
1350 return (error);
1351 }
1352
1353 /* System calls. */
1354 #ifdef COMPAT_FREEBSD12
1355 int
freebsd12_shm_open(struct thread * td,struct freebsd12_shm_open_args * uap)1356 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap)
1357 {
1358
1359 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC,
1360 uap->mode, NULL));
1361 }
1362 #endif
1363
1364 int
sys_shm_unlink(struct thread * td,struct shm_unlink_args * uap)1365 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
1366 {
1367 char *path;
1368 Fnv32_t fnv;
1369 int error;
1370
1371 error = shm_copyin_path(td, uap->path, &path);
1372 if (error != 0)
1373 return (error);
1374
1375 AUDIT_ARG_UPATH1_CANON(path);
1376 fnv = fnv_32_str(path, FNV1_32_INIT);
1377 sx_xlock(&shm_dict_lock);
1378 error = shm_remove(path, fnv, td->td_ucred);
1379 sx_xunlock(&shm_dict_lock);
1380 free(path, M_SHMFD);
1381
1382 return (error);
1383 }
1384
1385 int
sys_shm_rename(struct thread * td,struct shm_rename_args * uap)1386 sys_shm_rename(struct thread *td, struct shm_rename_args *uap)
1387 {
1388 char *path_from = NULL, *path_to = NULL;
1389 Fnv32_t fnv_from, fnv_to;
1390 struct shmfd *fd_from;
1391 struct shmfd *fd_to;
1392 int error;
1393 int flags;
1394
1395 flags = uap->flags;
1396 AUDIT_ARG_FFLAGS(flags);
1397
1398 /*
1399 * Make sure the user passed only valid flags.
1400 * If you add a new flag, please add a new term here.
1401 */
1402 if ((flags & ~(
1403 SHM_RENAME_NOREPLACE |
1404 SHM_RENAME_EXCHANGE
1405 )) != 0) {
1406 error = EINVAL;
1407 goto out;
1408 }
1409
1410 /*
1411 * EXCHANGE and NOREPLACE don't quite make sense together. Let's
1412 * force the user to choose one or the other.
1413 */
1414 if ((flags & SHM_RENAME_NOREPLACE) != 0 &&
1415 (flags & SHM_RENAME_EXCHANGE) != 0) {
1416 error = EINVAL;
1417 goto out;
1418 }
1419
1420 /* Renaming to or from anonymous makes no sense */
1421 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) {
1422 error = EINVAL;
1423 goto out;
1424 }
1425
1426 error = shm_copyin_path(td, uap->path_from, &path_from);
1427 if (error != 0)
1428 goto out;
1429
1430 error = shm_copyin_path(td, uap->path_to, &path_to);
1431 if (error != 0)
1432 goto out;
1433
1434 AUDIT_ARG_UPATH1_CANON(path_from);
1435 AUDIT_ARG_UPATH2_CANON(path_to);
1436
1437 /* Rename with from/to equal is a no-op */
1438 if (strcmp(path_from, path_to) == 0)
1439 goto out;
1440
1441 fnv_from = fnv_32_str(path_from, FNV1_32_INIT);
1442 fnv_to = fnv_32_str(path_to, FNV1_32_INIT);
1443
1444 sx_xlock(&shm_dict_lock);
1445
1446 fd_from = shm_lookup(path_from, fnv_from);
1447 if (fd_from == NULL) {
1448 error = ENOENT;
1449 goto out_locked;
1450 }
1451
1452 fd_to = shm_lookup(path_to, fnv_to);
1453 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) {
1454 error = EEXIST;
1455 goto out_locked;
1456 }
1457
1458 /*
1459 * Unconditionally prevents shm_remove from invalidating the 'from'
1460 * shm's state.
1461 */
1462 shm_hold(fd_from);
1463 error = shm_remove(path_from, fnv_from, td->td_ucred);
1464
1465 /*
1466 * One of my assumptions failed if ENOENT (e.g. locking didn't
1467 * protect us)
1468 */
1469 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s",
1470 path_from));
1471 if (error != 0) {
1472 shm_drop(fd_from);
1473 goto out_locked;
1474 }
1475
1476 /*
1477 * If we are exchanging, we need to ensure the shm_remove below
1478 * doesn't invalidate the dest shm's state.
1479 */
1480 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL)
1481 shm_hold(fd_to);
1482
1483 /*
1484 * NOTE: if path_to is not already in the hash, c'est la vie;
1485 * it simply means we have nothing already at path_to to unlink.
1486 * That is the ENOENT case.
1487 *
1488 * If we somehow don't have access to unlink this guy, but
1489 * did for the shm at path_from, then relink the shm to path_from
1490 * and abort with EACCES.
1491 *
1492 * All other errors: that is weird; let's relink and abort the
1493 * operation.
1494 */
1495 error = shm_remove(path_to, fnv_to, td->td_ucred);
1496 if (error != 0 && error != ENOENT) {
1497 shm_insert(path_from, fnv_from, fd_from);
1498 shm_drop(fd_from);
1499 /* Don't free path_from now, since the hash references it */
1500 path_from = NULL;
1501 goto out_locked;
1502 }
1503
1504 error = 0;
1505
1506 shm_insert(path_to, fnv_to, fd_from);
1507
1508 /* Don't free path_to now, since the hash references it */
1509 path_to = NULL;
1510
1511 /* We kept a ref when we removed, and incremented again in insert */
1512 shm_drop(fd_from);
1513 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1514 fd_from->shm_refs));
1515
1516 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) {
1517 shm_insert(path_from, fnv_from, fd_to);
1518 path_from = NULL;
1519 shm_drop(fd_to);
1520 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n",
1521 fd_to->shm_refs));
1522 }
1523
1524 out_locked:
1525 sx_xunlock(&shm_dict_lock);
1526
1527 out:
1528 free(path_from, M_SHMFD);
1529 free(path_to, M_SHMFD);
1530 return (error);
1531 }
1532
1533 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)1534 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr,
1535 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags,
1536 vm_ooffset_t foff, struct thread *td)
1537 {
1538 struct vmspace *vms;
1539 vm_map_entry_t next_entry, prev_entry;
1540 vm_offset_t align, mask, maxaddr;
1541 int docow, error, rv, try;
1542 bool curmap;
1543
1544 if (shmfd->shm_lp_psind == 0)
1545 return (EINVAL);
1546
1547 /* MAP_PRIVATE is disabled */
1548 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL |
1549 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0)
1550 return (EINVAL);
1551
1552 vms = td->td_proc->p_vmspace;
1553 curmap = map == &vms->vm_map;
1554 if (curmap) {
1555 error = kern_mmap_racct_check(td, map, size);
1556 if (error != 0)
1557 return (error);
1558 }
1559
1560 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT;
1561 docow |= MAP_INHERIT_SHARE;
1562 if ((flags & MAP_NOCORE) != 0)
1563 docow |= MAP_DISABLE_COREDUMP;
1564
1565 mask = pagesizes[shmfd->shm_lp_psind] - 1;
1566 if ((foff & mask) != 0)
1567 return (EINVAL);
1568 maxaddr = vm_map_max(map);
1569 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR)
1570 maxaddr = MAP_32BIT_MAX_ADDR;
1571 if (size == 0 || (size & mask) != 0 ||
1572 (*addr != 0 && ((*addr & mask) != 0 ||
1573 *addr + size < *addr || *addr + size > maxaddr)))
1574 return (EINVAL);
1575
1576 align = flags & MAP_ALIGNMENT_MASK;
1577 if (align == 0) {
1578 align = pagesizes[shmfd->shm_lp_psind];
1579 } else if (align == MAP_ALIGNED_SUPER) {
1580 /*
1581 * MAP_ALIGNED_SUPER is only supported on superpage sizes,
1582 * i.e., [1, VM_NRESERVLEVEL]. shmfd->shm_lp_psind < 1 is
1583 * handled above.
1584 */
1585 if (
1586 #if VM_NRESERVLEVEL > 0
1587 shmfd->shm_lp_psind > VM_NRESERVLEVEL
1588 #else
1589 shmfd->shm_lp_psind > 1
1590 #endif
1591 )
1592 return (EINVAL);
1593 align = pagesizes[shmfd->shm_lp_psind];
1594 } else {
1595 align >>= MAP_ALIGNMENT_SHIFT;
1596 align = 1ULL << align;
1597 /* Also handles overflow. */
1598 if (align < pagesizes[shmfd->shm_lp_psind])
1599 return (EINVAL);
1600 }
1601
1602 vm_map_lock(map);
1603 if ((flags & MAP_FIXED) == 0) {
1604 try = 1;
1605 if (curmap && (*addr == 0 ||
1606 (*addr >= round_page((vm_offset_t)vms->vm_taddr) &&
1607 *addr < round_page((vm_offset_t)vms->vm_daddr +
1608 lim_max(td, RLIMIT_DATA))))) {
1609 *addr = roundup2((vm_offset_t)vms->vm_daddr +
1610 lim_max(td, RLIMIT_DATA),
1611 pagesizes[shmfd->shm_lp_psind]);
1612 }
1613 again:
1614 rv = vm_map_find_aligned(map, addr, size, maxaddr, align);
1615 if (rv != KERN_SUCCESS) {
1616 if (try == 1) {
1617 try = 2;
1618 *addr = vm_map_min(map);
1619 if ((*addr & mask) != 0)
1620 *addr = (*addr + mask) & mask;
1621 goto again;
1622 }
1623 goto fail1;
1624 }
1625 } else if ((flags & MAP_EXCL) == 0) {
1626 rv = vm_map_delete(map, *addr, *addr + size);
1627 if (rv != KERN_SUCCESS)
1628 goto fail1;
1629 } else {
1630 error = ENOSPC;
1631 if (vm_map_lookup_entry(map, *addr, &prev_entry))
1632 goto fail;
1633 next_entry = vm_map_entry_succ(prev_entry);
1634 if (next_entry->start < *addr + size)
1635 goto fail;
1636 }
1637
1638 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size,
1639 prot, max_prot, docow);
1640 fail1:
1641 error = vm_mmap_to_errno(rv);
1642 fail:
1643 vm_map_unlock(map);
1644 return (error);
1645 }
1646
1647 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)1648 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
1649 vm_prot_t prot, vm_prot_t max_maxprot, int flags,
1650 vm_ooffset_t foff, struct thread *td)
1651 {
1652 struct shmfd *shmfd;
1653 vm_prot_t maxprot;
1654 int error;
1655 bool writecnt;
1656 void *rl_cookie;
1657
1658 shmfd = fp->f_data;
1659 maxprot = VM_PROT_NONE;
1660
1661 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize);
1662 /* FREAD should always be set. */
1663 if ((fp->f_flag & FREAD) != 0)
1664 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
1665
1666 /*
1667 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared
1668 * mapping with a write seal applied. Private mappings are always
1669 * writeable.
1670 */
1671 if ((flags & MAP_SHARED) == 0) {
1672 if ((max_maxprot & VM_PROT_WRITE) != 0)
1673 maxprot |= VM_PROT_WRITE;
1674 writecnt = false;
1675 } else {
1676 if ((fp->f_flag & FWRITE) != 0 &&
1677 (shmfd->shm_seals & F_SEAL_WRITE) == 0)
1678 maxprot |= VM_PROT_WRITE;
1679
1680 /*
1681 * Any mappings from a writable descriptor may be upgraded to
1682 * VM_PROT_WRITE with mprotect(2), unless a write-seal was
1683 * applied between the open and subsequent mmap(2). We want to
1684 * reject application of a write seal as long as any such
1685 * mapping exists so that the seal cannot be trivially bypassed.
1686 */
1687 writecnt = (maxprot & VM_PROT_WRITE) != 0;
1688 if (!writecnt && (prot & VM_PROT_WRITE) != 0) {
1689 error = EACCES;
1690 goto out;
1691 }
1692 }
1693 maxprot &= max_maxprot;
1694
1695 /* See comment in vn_mmap(). */
1696 if (
1697 #ifdef _LP64
1698 objsize > OFF_MAX ||
1699 #endif
1700 foff > OFF_MAX - objsize) {
1701 error = EINVAL;
1702 goto out;
1703 }
1704
1705 #ifdef MAC
1706 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
1707 if (error != 0)
1708 goto out;
1709 #endif
1710
1711 mtx_lock(&shm_timestamp_lock);
1712 vfs_timestamp(&shmfd->shm_atime);
1713 mtx_unlock(&shm_timestamp_lock);
1714 vm_object_reference(shmfd->shm_object);
1715
1716 if (shm_largepage(shmfd)) {
1717 writecnt = false;
1718 error = shm_mmap_large(shmfd, map, addr, objsize, prot,
1719 maxprot, flags, foff, td);
1720 } else {
1721 if (writecnt) {
1722 vm_pager_update_writecount(shmfd->shm_object, 0,
1723 objsize);
1724 }
1725 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
1726 shmfd->shm_object, foff, writecnt, td);
1727 }
1728 if (error != 0) {
1729 if (writecnt)
1730 vm_pager_release_writecount(shmfd->shm_object, 0,
1731 objsize);
1732 vm_object_deallocate(shmfd->shm_object);
1733 }
1734 out:
1735 shm_rangelock_unlock(shmfd, rl_cookie);
1736 return (error);
1737 }
1738
1739 static int
shm_chmod(struct file * fp,mode_t mode,struct ucred * active_cred,struct thread * td)1740 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
1741 struct thread *td)
1742 {
1743 struct shmfd *shmfd;
1744 int error;
1745
1746 error = 0;
1747 shmfd = fp->f_data;
1748 mtx_lock(&shm_timestamp_lock);
1749 /*
1750 * SUSv4 says that x bits of permission need not be affected.
1751 * Be consistent with our shm_open there.
1752 */
1753 #ifdef MAC
1754 error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
1755 if (error != 0)
1756 goto out;
1757 #endif
1758 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
1759 VADMIN, active_cred);
1760 if (error != 0)
1761 goto out;
1762 shmfd->shm_mode = mode & ACCESSPERMS;
1763 out:
1764 mtx_unlock(&shm_timestamp_lock);
1765 return (error);
1766 }
1767
1768 static int
shm_chown(struct file * fp,uid_t uid,gid_t gid,struct ucred * active_cred,struct thread * td)1769 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
1770 struct thread *td)
1771 {
1772 struct shmfd *shmfd;
1773 int error;
1774
1775 error = 0;
1776 shmfd = fp->f_data;
1777 mtx_lock(&shm_timestamp_lock);
1778 #ifdef MAC
1779 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
1780 if (error != 0)
1781 goto out;
1782 #endif
1783 if (uid == (uid_t)-1)
1784 uid = shmfd->shm_uid;
1785 if (gid == (gid_t)-1)
1786 gid = shmfd->shm_gid;
1787 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
1788 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
1789 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
1790 goto out;
1791 shmfd->shm_uid = uid;
1792 shmfd->shm_gid = gid;
1793 out:
1794 mtx_unlock(&shm_timestamp_lock);
1795 return (error);
1796 }
1797
1798 /*
1799 * Helper routines to allow the backing object of a shared memory file
1800 * descriptor to be mapped in the kernel.
1801 */
1802 int
shm_map(struct file * fp,size_t size,off_t offset,void ** memp)1803 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
1804 {
1805 struct shmfd *shmfd;
1806 vm_offset_t kva, ofs;
1807 vm_object_t obj;
1808 int rv;
1809
1810 if (fp->f_type != DTYPE_SHM)
1811 return (EINVAL);
1812 shmfd = fp->f_data;
1813 obj = shmfd->shm_object;
1814 VM_OBJECT_WLOCK(obj);
1815 /*
1816 * XXXRW: This validation is probably insufficient, and subject to
1817 * sign errors. It should be fixed.
1818 */
1819 if (offset >= shmfd->shm_size ||
1820 offset + size > round_page(shmfd->shm_size)) {
1821 VM_OBJECT_WUNLOCK(obj);
1822 return (EINVAL);
1823 }
1824
1825 shmfd->shm_kmappings++;
1826 vm_object_reference_locked(obj);
1827 VM_OBJECT_WUNLOCK(obj);
1828
1829 /* Map the object into the kernel_map and wire it. */
1830 kva = vm_map_min(kernel_map);
1831 ofs = offset & PAGE_MASK;
1832 offset = trunc_page(offset);
1833 size = round_page(size + ofs);
1834 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1835 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1836 VM_PROT_READ | VM_PROT_WRITE, 0);
1837 if (rv == KERN_SUCCESS) {
1838 rv = vm_map_wire(kernel_map, kva, kva + size,
1839 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1840 if (rv == KERN_SUCCESS) {
1841 *memp = (void *)(kva + ofs);
1842 return (0);
1843 }
1844 vm_map_remove(kernel_map, kva, kva + size);
1845 } else
1846 vm_object_deallocate(obj);
1847
1848 /* On failure, drop our mapping reference. */
1849 VM_OBJECT_WLOCK(obj);
1850 shmfd->shm_kmappings--;
1851 VM_OBJECT_WUNLOCK(obj);
1852
1853 return (vm_mmap_to_errno(rv));
1854 }
1855
1856 /*
1857 * We require the caller to unmap the entire entry. This allows us to
1858 * safely decrement shm_kmappings when a mapping is removed.
1859 */
1860 int
shm_unmap(struct file * fp,void * mem,size_t size)1861 shm_unmap(struct file *fp, void *mem, size_t size)
1862 {
1863 struct shmfd *shmfd;
1864 vm_map_entry_t entry;
1865 vm_offset_t kva, ofs;
1866 vm_object_t obj;
1867 vm_pindex_t pindex;
1868 vm_prot_t prot;
1869 boolean_t wired;
1870 vm_map_t map;
1871 int rv;
1872
1873 if (fp->f_type != DTYPE_SHM)
1874 return (EINVAL);
1875 shmfd = fp->f_data;
1876 kva = (vm_offset_t)mem;
1877 ofs = kva & PAGE_MASK;
1878 kva = trunc_page(kva);
1879 size = round_page(size + ofs);
1880 map = kernel_map;
1881 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1882 &obj, &pindex, &prot, &wired);
1883 if (rv != KERN_SUCCESS)
1884 return (EINVAL);
1885 if (entry->start != kva || entry->end != kva + size) {
1886 vm_map_lookup_done(map, entry);
1887 return (EINVAL);
1888 }
1889 vm_map_lookup_done(map, entry);
1890 if (obj != shmfd->shm_object)
1891 return (EINVAL);
1892 vm_map_remove(map, kva, kva + size);
1893 VM_OBJECT_WLOCK(obj);
1894 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1895 shmfd->shm_kmappings--;
1896 VM_OBJECT_WUNLOCK(obj);
1897 return (0);
1898 }
1899
1900 static int
shm_fill_kinfo_locked(struct shmfd * shmfd,struct kinfo_file * kif,bool list)1901 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1902 {
1903 const char *path, *pr_path;
1904 size_t pr_pathlen;
1905 bool visible;
1906
1907 sx_assert(&shm_dict_lock, SA_LOCKED);
1908 kif->kf_type = KF_TYPE_SHM;
1909 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1910 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1911 if (shmfd->shm_path != NULL) {
1912 path = shmfd->shm_path;
1913 pr_path = curthread->td_ucred->cr_prison->pr_path;
1914 if (strcmp(pr_path, "/") != 0) {
1915 /* Return the jail-rooted pathname. */
1916 pr_pathlen = strlen(pr_path);
1917 visible = strncmp(path, pr_path, pr_pathlen) == 0 &&
1918 path[pr_pathlen] == '/';
1919 if (list && !visible)
1920 return (EPERM);
1921 if (visible)
1922 path += pr_pathlen;
1923 }
1924 strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1925 }
1926 return (0);
1927 }
1928
1929 static int
shm_fill_kinfo(struct file * fp,struct kinfo_file * kif,struct filedesc * fdp __unused)1930 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1931 struct filedesc *fdp __unused)
1932 {
1933 int res;
1934
1935 sx_slock(&shm_dict_lock);
1936 res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1937 sx_sunlock(&shm_dict_lock);
1938 return (res);
1939 }
1940
1941 static int
shm_add_seals(struct file * fp,int seals)1942 shm_add_seals(struct file *fp, int seals)
1943 {
1944 struct shmfd *shmfd;
1945 void *rl_cookie;
1946 vm_ooffset_t writemappings;
1947 int error, nseals;
1948
1949 error = 0;
1950 shmfd = fp->f_data;
1951 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX);
1952
1953 /* Even already-set seals should result in EPERM. */
1954 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) {
1955 error = EPERM;
1956 goto out;
1957 }
1958 nseals = seals & ~shmfd->shm_seals;
1959 if ((nseals & F_SEAL_WRITE) != 0) {
1960 if (shm_largepage(shmfd)) {
1961 error = ENOTSUP;
1962 goto out;
1963 }
1964
1965 /*
1966 * The rangelock above prevents writable mappings from being
1967 * added after we've started applying seals. The RLOCK here
1968 * is to avoid torn reads on ILP32 arches as unmapping/reducing
1969 * writemappings will be done without a rangelock.
1970 */
1971 VM_OBJECT_RLOCK(shmfd->shm_object);
1972 writemappings = shmfd->shm_object->un_pager.swp.writemappings;
1973 VM_OBJECT_RUNLOCK(shmfd->shm_object);
1974 /* kmappings are also writable */
1975 if (writemappings > 0) {
1976 error = EBUSY;
1977 goto out;
1978 }
1979 }
1980 shmfd->shm_seals |= nseals;
1981 out:
1982 shm_rangelock_unlock(shmfd, rl_cookie);
1983 return (error);
1984 }
1985
1986 static int
shm_get_seals(struct file * fp,int * seals)1987 shm_get_seals(struct file *fp, int *seals)
1988 {
1989 struct shmfd *shmfd;
1990
1991 shmfd = fp->f_data;
1992 *seals = shmfd->shm_seals;
1993 return (0);
1994 }
1995
1996 static int
shm_deallocate(struct shmfd * shmfd,off_t * offset,off_t * length,int flags)1997 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags)
1998 {
1999 vm_object_t object;
2000 vm_pindex_t pistart, pi, piend;
2001 vm_ooffset_t off, len;
2002 int startofs, endofs, end;
2003 int error;
2004
2005 off = *offset;
2006 len = *length;
2007 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
2008 if (off + len > shmfd->shm_size)
2009 len = shmfd->shm_size - off;
2010 object = shmfd->shm_object;
2011 startofs = off & PAGE_MASK;
2012 endofs = (off + len) & PAGE_MASK;
2013 pistart = OFF_TO_IDX(off);
2014 piend = OFF_TO_IDX(off + len);
2015 pi = OFF_TO_IDX(off + PAGE_MASK);
2016 error = 0;
2017
2018 /* Handle the case when offset is on or beyond shm size. */
2019 if ((off_t)len <= 0) {
2020 *length = 0;
2021 return (0);
2022 }
2023
2024 VM_OBJECT_WLOCK(object);
2025
2026 if (startofs != 0) {
2027 end = pistart != piend ? PAGE_SIZE : endofs;
2028 error = shm_partial_page_invalidate(object, pistart, startofs,
2029 end);
2030 if (error)
2031 goto out;
2032 off += end - startofs;
2033 len -= end - startofs;
2034 }
2035
2036 if (pi < piend) {
2037 vm_object_page_remove(object, pi, piend, 0);
2038 off += IDX_TO_OFF(piend - pi);
2039 len -= IDX_TO_OFF(piend - pi);
2040 }
2041
2042 if (endofs != 0 && pistart != piend) {
2043 error = shm_partial_page_invalidate(object, piend, 0, endofs);
2044 if (error)
2045 goto out;
2046 off += endofs;
2047 len -= endofs;
2048 }
2049
2050 out:
2051 VM_OBJECT_WUNLOCK(shmfd->shm_object);
2052 *offset = off;
2053 *length = len;
2054 return (error);
2055 }
2056
2057 static int
shm_fspacectl(struct file * fp,int cmd,off_t * offset,off_t * length,int flags,struct ucred * active_cred,struct thread * td)2058 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags,
2059 struct ucred *active_cred, struct thread *td)
2060 {
2061 void *rl_cookie;
2062 struct shmfd *shmfd;
2063 off_t off, len;
2064 int error;
2065
2066 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd"));
2067 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0,
2068 ("shm_fspacectl: non-zero flags"));
2069 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset,
2070 ("shm_fspacectl: offset/length overflow or underflow"));
2071 error = EINVAL;
2072 shmfd = fp->f_data;
2073 off = *offset;
2074 len = *length;
2075
2076 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len);
2077 switch (cmd) {
2078 case SPACECTL_DEALLOC:
2079 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) {
2080 error = EPERM;
2081 break;
2082 }
2083 error = shm_deallocate(shmfd, &off, &len, flags);
2084 *offset = off;
2085 *length = len;
2086 break;
2087 default:
2088 __assert_unreachable();
2089 }
2090 shm_rangelock_unlock(shmfd, rl_cookie);
2091 return (error);
2092 }
2093
2094
2095 static int
shm_fallocate(struct file * fp,off_t offset,off_t len,struct thread * td)2096 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td)
2097 {
2098 void *rl_cookie;
2099 struct shmfd *shmfd;
2100 size_t size;
2101 int error;
2102
2103 /* This assumes that the caller already checked for overflow. */
2104 error = 0;
2105 shmfd = fp->f_data;
2106 size = offset + len;
2107
2108 /*
2109 * Just grab the rangelock for the range that we may be attempting to
2110 * grow, rather than blocking read/write for regions we won't be
2111 * touching while this (potential) resize is in progress. Other
2112 * attempts to resize the shmfd will have to take a write lock from 0 to
2113 * OFF_MAX, so this being potentially beyond the current usable range of
2114 * the shmfd is not necessarily a concern. If other mechanisms are
2115 * added to grow a shmfd, this may need to be re-evaluated.
2116 */
2117 rl_cookie = shm_rangelock_wlock(shmfd, offset, size);
2118 if (size > shmfd->shm_size)
2119 error = shm_dotruncate_cookie(shmfd, size, rl_cookie);
2120 shm_rangelock_unlock(shmfd, rl_cookie);
2121 /* Translate to posix_fallocate(2) return value as needed. */
2122 if (error == ENOMEM)
2123 error = ENOSPC;
2124 return (error);
2125 }
2126
2127 static int
sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)2128 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
2129 {
2130 struct shm_mapping *shmm;
2131 struct sbuf sb;
2132 struct kinfo_file kif;
2133 u_long i;
2134 int error, error2;
2135
2136 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
2137 sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
2138 error = 0;
2139 sx_slock(&shm_dict_lock);
2140 for (i = 0; i < shm_hash + 1; i++) {
2141 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
2142 error = shm_fill_kinfo_locked(shmm->sm_shmfd,
2143 &kif, true);
2144 if (error == EPERM) {
2145 error = 0;
2146 continue;
2147 }
2148 if (error != 0)
2149 break;
2150 pack_kinfo(&kif);
2151 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
2152 0 : ENOMEM;
2153 if (error != 0)
2154 break;
2155 }
2156 }
2157 sx_sunlock(&shm_dict_lock);
2158 error2 = sbuf_finish(&sb);
2159 sbuf_delete(&sb);
2160 return (error != 0 ? error : error2);
2161 }
2162
2163 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
2164 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
2165 NULL, 0, sysctl_posix_shm_list, "",
2166 "POSIX SHM list");
2167
2168 int
kern_shm_open(struct thread * td,const char * path,int flags,mode_t mode,struct filecaps * caps)2169 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode,
2170 struct filecaps *caps)
2171 {
2172
2173 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL));
2174 }
2175
2176 /*
2177 * This version of the shm_open() interface leaves CLOEXEC behavior up to the
2178 * caller, and libc will enforce it for the traditional shm_open() call. This
2179 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This
2180 * interface also includes a 'name' argument that is currently unused, but could
2181 * potentially be exported later via some interface for debugging purposes.
2182 * From the kernel's perspective, it is optional. Individual consumers like
2183 * memfd_create() may require it in order to be compatible with other systems
2184 * implementing the same function.
2185 */
2186 int
sys_shm_open2(struct thread * td,struct shm_open2_args * uap)2187 sys_shm_open2(struct thread *td, struct shm_open2_args *uap)
2188 {
2189
2190 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode,
2191 uap->shmflags, NULL, uap->name));
2192 }
2193
2194 int
shm_get_path(struct vm_object * obj,char * path,size_t sz)2195 shm_get_path(struct vm_object *obj, char *path, size_t sz)
2196 {
2197 struct shmfd *shmfd;
2198 int error;
2199
2200 error = 0;
2201 shmfd = NULL;
2202 sx_slock(&shm_dict_lock);
2203 VM_OBJECT_RLOCK(obj);
2204 if ((obj->flags & OBJ_POSIXSHM) == 0) {
2205 error = EINVAL;
2206 } else {
2207 if (obj->type == shmfd_pager_type)
2208 shmfd = obj->un_pager.swp.swp_priv;
2209 else if (obj->type == OBJT_PHYS)
2210 shmfd = obj->un_pager.phys.phys_priv;
2211 if (shmfd == NULL) {
2212 error = ENXIO;
2213 } else {
2214 strlcpy(path, shmfd->shm_path == NULL ? "anon" :
2215 shmfd->shm_path, sz);
2216 }
2217 }
2218 if (error != 0)
2219 path[0] = '\0';
2220 VM_OBJECT_RUNLOCK(obj);
2221 sx_sunlock(&shm_dict_lock);
2222 return (error);
2223 }
2224