1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 5 * Copyright 2020 The FreeBSD Foundation 6 * All rights reserved. 7 * 8 * Portions of this software were developed by BAE Systems, the University of 9 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 10 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 11 * Computing (TC) research program. 12 * 13 * Portions of this software were developed by Konstantin Belousov 14 * under sponsorship from the FreeBSD Foundation. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38/* 39 * Support for shared swap-backed anonymous memory objects via 40 * shm_open(2), shm_rename(2), and shm_unlink(2). 41 * While most of the implementation is here, vm_mmap.c contains 42 * mapping logic changes. 43 * 44 * posixshmcontrol(1) allows users to inspect the state of the memory 45 * objects. Per-uid swap resource limit controls total amount of 46 * memory that user can consume for anonymous objects, including 47 * shared. 48 */ 49 50#include <sys/cdefs.h> 51__FBSDID("$FreeBSD$"); 52 53#include "opt_capsicum.h" 54#include "opt_ktrace.h" 55 56#include <sys/param.h> 57#include <sys/capsicum.h> 58#include <sys/conf.h> 59#include <sys/fcntl.h> 60#include <sys/file.h> 61#include <sys/filedesc.h> 62#include <sys/filio.h> 63#include <sys/fnv_hash.h> 64#include <sys/kernel.h> 65#include <sys/limits.h> 66#include <sys/uio.h> 67#include <sys/signal.h> 68#include <sys/jail.h> 69#include <sys/ktrace.h> 70#include <sys/lock.h> 71#include <sys/malloc.h> 72#include <sys/mman.h> 73#include <sys/mutex.h> 74#include <sys/priv.h> 75#include <sys/proc.h> 76#include <sys/refcount.h> 77#include <sys/resourcevar.h> 78#include <sys/rwlock.h> 79#include <sys/sbuf.h> 80#include <sys/stat.h> 81#include <sys/syscallsubr.h> 82#include <sys/sysctl.h> 83#include <sys/sysproto.h> 84#include <sys/systm.h> 85#include <sys/sx.h> 86#include <sys/time.h> 87#include <sys/vmmeter.h> 88#include <sys/vnode.h> 89#include <sys/unistd.h> 90#include <sys/user.h> 91 92#include <security/audit/audit.h> 93#include <security/mac/mac_framework.h> 94 95#include <vm/vm.h> 96#include <vm/vm_param.h> 97#include <vm/pmap.h> 98#include <vm/vm_extern.h> 99#include <vm/vm_map.h> 100#include <vm/vm_kern.h> 101#include <vm/vm_object.h> 102#include <vm/vm_page.h> 103#include <vm/vm_pageout.h> 104#include <vm/vm_pager.h> 105#include <vm/swap_pager.h> 106 107struct shm_mapping { 108 char *sm_path; 109 Fnv32_t sm_fnv; 110 struct shmfd *sm_shmfd; 111 LIST_ENTRY(shm_mapping) sm_link; 112}; 113 114static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 115static LIST_HEAD(, shm_mapping) *shm_dictionary; 116static struct sx shm_dict_lock; 117static struct mtx shm_timestamp_lock; 118static u_long shm_hash; 119static struct unrhdr64 shm_ino_unr; 120static dev_t shm_dev_ino; 121 122#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 123 124static void shm_init(void *arg); 125static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 126static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 127static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 128static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 129 void *rl_cookie); 130static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 131 void *rl_cookie); 132static int shm_copyin_path(struct thread *td, const char *userpath_in, 133 char **path_out); 134 135static fo_rdwr_t shm_read; 136static fo_rdwr_t shm_write; 137static fo_truncate_t shm_truncate; 138static fo_ioctl_t shm_ioctl; 139static fo_stat_t shm_stat; 140static fo_close_t shm_close; 141static fo_chmod_t shm_chmod; 142static fo_chown_t shm_chown; 143static fo_seek_t shm_seek; 144static fo_fill_kinfo_t shm_fill_kinfo; 145static fo_mmap_t shm_mmap; 146static fo_get_seals_t shm_get_seals; 147static fo_add_seals_t shm_add_seals; 148static fo_fallocate_t shm_fallocate; 149 150/* File descriptor operations. */ 151struct fileops shm_ops = { 152 .fo_read = shm_read, 153 .fo_write = shm_write, 154 .fo_truncate = shm_truncate, 155 .fo_ioctl = shm_ioctl, 156 .fo_poll = invfo_poll, 157 .fo_kqfilter = invfo_kqfilter, 158 .fo_stat = shm_stat, 159 .fo_close = shm_close, 160 .fo_chmod = shm_chmod, 161 .fo_chown = shm_chown, 162 .fo_sendfile = vn_sendfile, 163 .fo_seek = shm_seek, 164 .fo_fill_kinfo = shm_fill_kinfo, 165 .fo_mmap = shm_mmap, 166 .fo_get_seals = shm_get_seals, 167 .fo_add_seals = shm_add_seals, 168 .fo_fallocate = shm_fallocate, 169 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 170}; 171 172FEATURE(posix_shm, "POSIX shared memory"); 173 174static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 175 ""); 176 177static int largepage_reclaim_tries = 1; 178SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 179 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 180 "Number of contig reclaims before giving up for default alloc policy"); 181 182static int 183uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 184{ 185 vm_page_t m; 186 vm_pindex_t idx; 187 size_t tlen; 188 int error, offset, rv; 189 190 idx = OFF_TO_IDX(uio->uio_offset); 191 offset = uio->uio_offset & PAGE_MASK; 192 tlen = MIN(PAGE_SIZE - offset, len); 193 194 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 195 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 196 if (rv == VM_PAGER_OK) 197 goto found; 198 199 /* 200 * Read I/O without either a corresponding resident page or swap 201 * page: use zero_region. This is intended to avoid instantiating 202 * pages on read from a sparse region. 203 */ 204 VM_OBJECT_WLOCK(obj); 205 m = vm_page_lookup(obj, idx); 206 if (uio->uio_rw == UIO_READ && m == NULL && 207 !vm_pager_has_page(obj, idx, NULL, NULL)) { 208 VM_OBJECT_WUNLOCK(obj); 209 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 210 } 211 212 /* 213 * Although the tmpfs vnode lock is held here, it is 214 * nonetheless safe to sleep waiting for a free page. The 215 * pageout daemon does not need to acquire the tmpfs vnode 216 * lock to page out tobj's pages because tobj is a OBJT_SWAP 217 * type object. 218 */ 219 rv = vm_page_grab_valid(&m, obj, idx, 220 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 221 if (rv != VM_PAGER_OK) { 222 VM_OBJECT_WUNLOCK(obj); 223 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 224 obj, idx, rv); 225 return (EIO); 226 } 227 VM_OBJECT_WUNLOCK(obj); 228 229found: 230 error = uiomove_fromphys(&m, offset, tlen, uio); 231 if (uio->uio_rw == UIO_WRITE && error == 0) 232 vm_page_set_dirty(m); 233 vm_page_activate(m); 234 vm_page_sunbusy(m); 235 236 return (error); 237} 238 239int 240uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 241{ 242 ssize_t resid; 243 size_t len; 244 int error; 245 246 error = 0; 247 while ((resid = uio->uio_resid) > 0) { 248 if (obj_size <= uio->uio_offset) 249 break; 250 len = MIN(obj_size - uio->uio_offset, resid); 251 if (len == 0) 252 break; 253 error = uiomove_object_page(obj, len, uio); 254 if (error != 0 || resid == uio->uio_resid) 255 break; 256 } 257 return (error); 258} 259 260static u_long count_largepages[MAXPAGESIZES]; 261 262static int 263shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 264 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 265{ 266 vm_page_t m; 267 int psind; 268 269 psind = object->un_pager.phys.data_val; 270 if (psind == 0 || pidx >= object->size) 271 return (VM_PAGER_FAIL); 272 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 273 274 /* 275 * We only busy the first page in the superpage run. It is 276 * useless to busy whole run since we only remove full 277 * superpage, and it takes too long to busy e.g. 512 * 512 == 278 * 262144 pages constituing 1G amd64 superage. 279 */ 280 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 281 MPASS(m != NULL); 282 283 *last = *first + atop(pagesizes[psind]) - 1; 284 return (VM_PAGER_OK); 285} 286 287static boolean_t 288shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 289 int *before, int *after) 290{ 291 int psind; 292 293 psind = object->un_pager.phys.data_val; 294 if (psind == 0 || pindex >= object->size) 295 return (FALSE); 296 if (before != NULL) { 297 *before = pindex - rounddown2(pindex, pagesizes[psind] / 298 PAGE_SIZE); 299 } 300 if (after != NULL) { 301 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 302 pindex; 303 } 304 return (TRUE); 305} 306 307static void 308shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 309 vm_ooffset_t foff, struct ucred *cred) 310{ 311} 312 313static void 314shm_largepage_phys_dtor(vm_object_t object) 315{ 316 int psind; 317 318 psind = object->un_pager.phys.data_val; 319 if (psind != 0) { 320 atomic_subtract_long(&count_largepages[psind], 321 object->size / (pagesizes[psind] / PAGE_SIZE)); 322 vm_wire_sub(object->size); 323 } else { 324 KASSERT(object->size == 0, 325 ("largepage phys obj %p not initialized bit size %#jx > 0", 326 object, (uintmax_t)object->size)); 327 } 328} 329 330static const struct phys_pager_ops shm_largepage_phys_ops = { 331 .phys_pg_populate = shm_largepage_phys_populate, 332 .phys_pg_haspage = shm_largepage_phys_haspage, 333 .phys_pg_ctor = shm_largepage_phys_ctor, 334 .phys_pg_dtor = shm_largepage_phys_dtor, 335}; 336 337bool 338shm_largepage(struct shmfd *shmfd) 339{ 340 return (shmfd->shm_object->type == OBJT_PHYS); 341} 342 343static int 344shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 345{ 346 struct shmfd *shmfd; 347 off_t foffset; 348 int error; 349 350 shmfd = fp->f_data; 351 foffset = foffset_lock(fp, 0); 352 error = 0; 353 switch (whence) { 354 case L_INCR: 355 if (foffset < 0 || 356 (offset > 0 && foffset > OFF_MAX - offset)) { 357 error = EOVERFLOW; 358 break; 359 } 360 offset += foffset; 361 break; 362 case L_XTND: 363 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 364 error = EOVERFLOW; 365 break; 366 } 367 offset += shmfd->shm_size; 368 break; 369 case L_SET: 370 break; 371 default: 372 error = EINVAL; 373 } 374 if (error == 0) { 375 if (offset < 0 || offset > shmfd->shm_size) 376 error = EINVAL; 377 else 378 td->td_uretoff.tdu_off = offset; 379 } 380 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 381 return (error); 382} 383 384static int 385shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 386 int flags, struct thread *td) 387{ 388 struct shmfd *shmfd; 389 void *rl_cookie; 390 int error; 391 392 shmfd = fp->f_data; 393#ifdef MAC 394 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 395 if (error) 396 return (error); 397#endif 398 foffset_lock_uio(fp, uio, flags); 399 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 400 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 401 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 402 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 403 foffset_unlock_uio(fp, uio, flags); 404 return (error); 405} 406 407static int 408shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 409 int flags, struct thread *td) 410{ 411 struct shmfd *shmfd; 412 void *rl_cookie; 413 int error; 414 off_t size; 415 416 shmfd = fp->f_data; 417#ifdef MAC 418 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 419 if (error) 420 return (error); 421#endif 422 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 423 return (EINVAL); 424 foffset_lock_uio(fp, uio, flags); 425 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 426 /* 427 * Overflow is only an error if we're supposed to expand on 428 * write. Otherwise, we'll just truncate the write to the 429 * size of the file, which can only grow up to OFF_MAX. 430 */ 431 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 432 foffset_unlock_uio(fp, uio, flags); 433 return (EFBIG); 434 } 435 436 size = shmfd->shm_size; 437 } else { 438 size = uio->uio_offset + uio->uio_resid; 439 } 440 if ((flags & FOF_OFFSET) == 0) { 441 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 442 &shmfd->shm_mtx); 443 } else { 444 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 445 size, &shmfd->shm_mtx); 446 } 447 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 448 error = EPERM; 449 } else { 450 error = 0; 451 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 452 size > shmfd->shm_size) { 453 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 454 } 455 if (error == 0) 456 error = uiomove_object(shmfd->shm_object, 457 shmfd->shm_size, uio); 458 } 459 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 460 foffset_unlock_uio(fp, uio, flags); 461 return (error); 462} 463 464static int 465shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 466 struct thread *td) 467{ 468 struct shmfd *shmfd; 469#ifdef MAC 470 int error; 471#endif 472 473 shmfd = fp->f_data; 474#ifdef MAC 475 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 476 if (error) 477 return (error); 478#endif 479 return (shm_dotruncate(shmfd, length)); 480} 481 482int 483shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 484 struct thread *td) 485{ 486 struct shmfd *shmfd; 487 struct shm_largepage_conf *conf; 488 void *rl_cookie; 489 490 shmfd = fp->f_data; 491 switch (com) { 492 case FIONBIO: 493 case FIOASYNC: 494 /* 495 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 496 * just like it would on an unlinked regular file 497 */ 498 return (0); 499 case FIOSSHMLPGCNF: 500 if (!shm_largepage(shmfd)) 501 return (ENOTTY); 502 conf = data; 503 if (shmfd->shm_lp_psind != 0 && 504 conf->psind != shmfd->shm_lp_psind) 505 return (EINVAL); 506 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 507 pagesizes[conf->psind] == 0) 508 return (EINVAL); 509 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 510 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 511 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 512 return (EINVAL); 513 514 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 515 &shmfd->shm_mtx); 516 shmfd->shm_lp_psind = conf->psind; 517 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 518 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 519 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 520 return (0); 521 case FIOGSHMLPGCNF: 522 if (!shm_largepage(shmfd)) 523 return (ENOTTY); 524 conf = data; 525 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX, 526 &shmfd->shm_mtx); 527 conf->psind = shmfd->shm_lp_psind; 528 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 529 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 530 return (0); 531 default: 532 return (ENOTTY); 533 } 534} 535 536static int 537shm_stat(struct file *fp, struct stat *sb, 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; 546 547#ifdef MAC 548 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 549 if (error) 550 return (error); 551#endif 552 553 /* 554 * Attempt to return sanish values for fstat() on a memory file 555 * descriptor. 556 */ 557 bzero(sb, sizeof(*sb)); 558 sb->st_blksize = PAGE_SIZE; 559 sb->st_size = shmfd->shm_size; 560 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 561 mtx_lock(&shm_timestamp_lock); 562 sb->st_atim = shmfd->shm_atime; 563 sb->st_ctim = shmfd->shm_ctime; 564 sb->st_mtim = shmfd->shm_mtime; 565 sb->st_birthtim = shmfd->shm_birthtime; 566 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 567 sb->st_uid = shmfd->shm_uid; 568 sb->st_gid = shmfd->shm_gid; 569 mtx_unlock(&shm_timestamp_lock); 570 sb->st_dev = shm_dev_ino; 571 sb->st_ino = shmfd->shm_ino; 572 sb->st_nlink = shmfd->shm_object->ref_count; 573 sb->st_blocks = shmfd->shm_object->size / 574 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 575 576 return (0); 577} 578 579static int 580shm_close(struct file *fp, struct thread *td) 581{ 582 struct shmfd *shmfd; 583 584 shmfd = fp->f_data; 585 fp->f_data = NULL; 586 shm_drop(shmfd); 587 588 return (0); 589} 590 591static int 592shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 593 int error; 594 char *path; 595 const char *pr_path; 596 size_t pr_pathlen; 597 598 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 599 pr_path = td->td_ucred->cr_prison->pr_path; 600 601 /* Construct a full pathname for jailed callers. */ 602 pr_pathlen = strcmp(pr_path, "/") == 603 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 604 error = copyinstr(userpath_in, path + pr_pathlen, 605 MAXPATHLEN - pr_pathlen, NULL); 606 if (error != 0) 607 goto out; 608 609#ifdef KTRACE 610 if (KTRPOINT(curthread, KTR_NAMEI)) 611 ktrnamei(path); 612#endif 613 614 /* Require paths to start with a '/' character. */ 615 if (path[pr_pathlen] != '/') { 616 error = EINVAL; 617 goto out; 618 } 619 620 *path_out = path; 621 622out: 623 if (error != 0) 624 free(path, M_SHMFD); 625 626 return (error); 627} 628 629static int 630shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 631{ 632 vm_object_t object; 633 vm_page_t m; 634 vm_pindex_t idx, nobjsize; 635 vm_ooffset_t delta; 636 int base, rv; 637 638 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 639 object = shmfd->shm_object; 640 VM_OBJECT_ASSERT_WLOCKED(object); 641 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 642 if (length == shmfd->shm_size) 643 return (0); 644 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 645 646 /* Are we shrinking? If so, trim the end. */ 647 if (length < shmfd->shm_size) { 648 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 649 return (EPERM); 650 651 /* 652 * Disallow any requests to shrink the size if this 653 * object is mapped into the kernel. 654 */ 655 if (shmfd->shm_kmappings > 0) 656 return (EBUSY); 657 658 /* 659 * Zero the truncated part of the last page. 660 */ 661 base = length & PAGE_MASK; 662 if (base != 0) { 663 idx = OFF_TO_IDX(length); 664retry: 665 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 666 if (m != NULL) { 667 MPASS(vm_page_all_valid(m)); 668 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 669 m = vm_page_alloc(object, idx, 670 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 671 if (m == NULL) 672 goto retry; 673 vm_object_pip_add(object, 1); 674 VM_OBJECT_WUNLOCK(object); 675 rv = vm_pager_get_pages(object, &m, 1, NULL, 676 NULL); 677 VM_OBJECT_WLOCK(object); 678 vm_object_pip_wakeup(object); 679 if (rv == VM_PAGER_OK) { 680 /* 681 * Since the page was not resident, 682 * and therefore not recently 683 * accessed, immediately enqueue it 684 * for asynchronous laundering. The 685 * current operation is not regarded 686 * as an access. 687 */ 688 vm_page_launder(m); 689 } else { 690 vm_page_free(m); 691 VM_OBJECT_WUNLOCK(object); 692 return (EIO); 693 } 694 } 695 if (m != NULL) { 696 pmap_zero_page_area(m, base, PAGE_SIZE - base); 697 KASSERT(vm_page_all_valid(m), 698 ("shm_dotruncate: page %p is invalid", m)); 699 vm_page_set_dirty(m); 700 vm_page_xunbusy(m); 701 } 702 } 703 delta = IDX_TO_OFF(object->size - nobjsize); 704 705 if (nobjsize < object->size) 706 vm_object_page_remove(object, nobjsize, object->size, 707 0); 708 709 /* Free the swap accounted for shm */ 710 swap_release_by_cred(delta, object->cred); 711 object->charge -= delta; 712 } else { 713 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 714 return (EPERM); 715 716 /* Try to reserve additional swap space. */ 717 delta = IDX_TO_OFF(nobjsize - object->size); 718 if (!swap_reserve_by_cred(delta, object->cred)) 719 return (ENOMEM); 720 object->charge += delta; 721 } 722 shmfd->shm_size = length; 723 mtx_lock(&shm_timestamp_lock); 724 vfs_timestamp(&shmfd->shm_ctime); 725 shmfd->shm_mtime = shmfd->shm_ctime; 726 mtx_unlock(&shm_timestamp_lock); 727 object->size = nobjsize; 728 return (0); 729} 730 731static int 732shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 733{ 734 vm_object_t object; 735 vm_page_t m; 736 vm_pindex_t newobjsz, oldobjsz; 737 int aflags, error, i, psind, try; 738 739 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 740 object = shmfd->shm_object; 741 VM_OBJECT_ASSERT_WLOCKED(object); 742 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 743 744 oldobjsz = object->size; 745 newobjsz = OFF_TO_IDX(length); 746 if (length == shmfd->shm_size) 747 return (0); 748 psind = shmfd->shm_lp_psind; 749 if (psind == 0 && length != 0) 750 return (EINVAL); 751 if ((length & (pagesizes[psind] - 1)) != 0) 752 return (EINVAL); 753 754 if (length < shmfd->shm_size) { 755 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 756 return (EPERM); 757 if (shmfd->shm_kmappings > 0) 758 return (EBUSY); 759 return (ENOTSUP); /* Pages are unmanaged. */ 760#if 0 761 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 762 object->size = newobjsz; 763 shmfd->shm_size = length; 764 return (0); 765#endif 766 } 767 768 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 769 return (EPERM); 770 771 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 772 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 773 aflags |= VM_ALLOC_WAITFAIL; 774 try = 0; 775 776 /* 777 * Extend shmfd and object, keeping all already fully 778 * allocated large pages intact even on error, because dropped 779 * object lock might allowed mapping of them. 780 */ 781 while (object->size < newobjsz) { 782 m = vm_page_alloc_contig(object, object->size, aflags, 783 pagesizes[psind] / PAGE_SIZE, 0, ~0, 784 pagesizes[psind], 0, 785 VM_MEMATTR_DEFAULT); 786 if (m == NULL) { 787 VM_OBJECT_WUNLOCK(object); 788 if (shmfd->shm_lp_alloc_policy == 789 SHM_LARGEPAGE_ALLOC_NOWAIT || 790 (shmfd->shm_lp_alloc_policy == 791 SHM_LARGEPAGE_ALLOC_DEFAULT && 792 try >= largepage_reclaim_tries)) { 793 VM_OBJECT_WLOCK(object); 794 return (ENOMEM); 795 } 796 error = vm_page_reclaim_contig(aflags, 797 pagesizes[psind] / PAGE_SIZE, 0, ~0, 798 pagesizes[psind], 0) ? 0 : 799 vm_wait_intr(object); 800 if (error != 0) { 801 VM_OBJECT_WLOCK(object); 802 return (error); 803 } 804 try++; 805 VM_OBJECT_WLOCK(object); 806 continue; 807 } 808 try = 0; 809 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 810 if ((m[i].flags & PG_ZERO) == 0) 811 pmap_zero_page(&m[i]); 812 vm_page_valid(&m[i]); 813 vm_page_xunbusy(&m[i]); 814 } 815 object->size += OFF_TO_IDX(pagesizes[psind]); 816 shmfd->shm_size += pagesizes[psind]; 817 atomic_add_long(&count_largepages[psind], 1); 818 vm_wire_add(atop(pagesizes[psind])); 819 } 820 return (0); 821} 822 823static int 824shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 825{ 826 int error; 827 828 VM_OBJECT_WLOCK(shmfd->shm_object); 829 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 830 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 831 rl_cookie); 832 VM_OBJECT_WUNLOCK(shmfd->shm_object); 833 return (error); 834} 835 836int 837shm_dotruncate(struct shmfd *shmfd, off_t length) 838{ 839 void *rl_cookie; 840 int error; 841 842 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 843 &shmfd->shm_mtx); 844 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 845 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 846 return (error); 847} 848 849/* 850 * shmfd object management including creation and reference counting 851 * routines. 852 */ 853struct shmfd * 854shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 855{ 856 struct shmfd *shmfd; 857 858 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 859 shmfd->shm_size = 0; 860 shmfd->shm_uid = ucred->cr_uid; 861 shmfd->shm_gid = ucred->cr_gid; 862 shmfd->shm_mode = mode; 863 if (largepage) { 864 shmfd->shm_object = phys_pager_allocate(NULL, 865 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 866 VM_PROT_DEFAULT, 0, ucred); 867 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 868 } else { 869 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 870 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 871 } 872 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 873 vfs_timestamp(&shmfd->shm_birthtime); 874 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 875 shmfd->shm_birthtime; 876 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 877 refcount_init(&shmfd->shm_refs, 1); 878 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 879 rangelock_init(&shmfd->shm_rl); 880#ifdef MAC 881 mac_posixshm_init(shmfd); 882 mac_posixshm_create(ucred, shmfd); 883#endif 884 885 return (shmfd); 886} 887 888struct shmfd * 889shm_hold(struct shmfd *shmfd) 890{ 891 892 refcount_acquire(&shmfd->shm_refs); 893 return (shmfd); 894} 895 896void 897shm_drop(struct shmfd *shmfd) 898{ 899 900 if (refcount_release(&shmfd->shm_refs)) { 901#ifdef MAC 902 mac_posixshm_destroy(shmfd); 903#endif 904 rangelock_destroy(&shmfd->shm_rl); 905 mtx_destroy(&shmfd->shm_mtx); 906 vm_object_deallocate(shmfd->shm_object); 907 free(shmfd, M_SHMFD); 908 } 909} 910 911/* 912 * Determine if the credentials have sufficient permissions for a 913 * specified combination of FREAD and FWRITE. 914 */ 915int 916shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 917{ 918 accmode_t accmode; 919 int error; 920 921 accmode = 0; 922 if (flags & FREAD) 923 accmode |= VREAD; 924 if (flags & FWRITE) 925 accmode |= VWRITE; 926 mtx_lock(&shm_timestamp_lock); 927 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 928 accmode, ucred); 929 mtx_unlock(&shm_timestamp_lock); 930 return (error); 931} 932 933static void 934shm_init(void *arg) 935{ 936 char name[32]; 937 int i; 938 939 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 940 sx_init(&shm_dict_lock, "shm dictionary"); 941 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 942 new_unrhdr64(&shm_ino_unr, 1); 943 shm_dev_ino = devfs_alloc_cdp_inode(); 944 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 945 946 for (i = 1; i < MAXPAGESIZES; i++) { 947 if (pagesizes[i] == 0) 948 break; 949#define M (1024 * 1024) 950#define G (1024 * M) 951 if (pagesizes[i] >= G) 952 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 953 else if (pagesizes[i] >= M) 954 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 955 else 956 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 957#undef G 958#undef M 959 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 960 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 961 "number of non-transient largepages allocated"); 962 } 963} 964SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 965 966/* 967 * Dictionary management. We maintain an in-kernel dictionary to map 968 * paths to shmfd objects. We use the FNV hash on the path to store 969 * the mappings in a hash table. 970 */ 971static struct shmfd * 972shm_lookup(char *path, Fnv32_t fnv) 973{ 974 struct shm_mapping *map; 975 976 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 977 if (map->sm_fnv != fnv) 978 continue; 979 if (strcmp(map->sm_path, path) == 0) 980 return (map->sm_shmfd); 981 } 982 983 return (NULL); 984} 985 986static void 987shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 988{ 989 struct shm_mapping *map; 990 991 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 992 map->sm_path = path; 993 map->sm_fnv = fnv; 994 map->sm_shmfd = shm_hold(shmfd); 995 shmfd->shm_path = path; 996 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 997} 998 999static int 1000shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1001{ 1002 struct shm_mapping *map; 1003 int error; 1004 1005 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1006 if (map->sm_fnv != fnv) 1007 continue; 1008 if (strcmp(map->sm_path, path) == 0) { 1009#ifdef MAC 1010 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1011 if (error) 1012 return (error); 1013#endif 1014 error = shm_access(map->sm_shmfd, ucred, 1015 FREAD | FWRITE); 1016 if (error) 1017 return (error); 1018 map->sm_shmfd->shm_path = NULL; 1019 LIST_REMOVE(map, sm_link); 1020 shm_drop(map->sm_shmfd); 1021 free(map->sm_path, M_SHMFD); 1022 free(map, M_SHMFD); 1023 return (0); 1024 } 1025 } 1026 1027 return (ENOENT); 1028} 1029 1030int 1031kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1032 int shmflags, struct filecaps *fcaps, const char *name __unused) 1033{ 1034 struct pwddesc *pdp; 1035 struct shmfd *shmfd; 1036 struct file *fp; 1037 char *path; 1038 void *rl_cookie; 1039 Fnv32_t fnv; 1040 mode_t cmode; 1041 int error, fd, initial_seals; 1042 bool largepage; 1043 1044 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1045 SHM_LARGEPAGE)) != 0) 1046 return (EINVAL); 1047 1048 initial_seals = F_SEAL_SEAL; 1049 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1050 initial_seals &= ~F_SEAL_SEAL; 1051 1052#ifdef CAPABILITY_MODE 1053 /* 1054 * shm_open(2) is only allowed for anonymous objects. 1055 */ 1056 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1057 return (ECAPMODE); 1058#endif 1059 1060 AUDIT_ARG_FFLAGS(flags); 1061 AUDIT_ARG_MODE(mode); 1062 1063 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1064 return (EINVAL); 1065 1066 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1067 return (EINVAL); 1068 1069 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1070 if (largepage && !PMAP_HAS_LARGEPAGES) 1071 return (ENOTTY); 1072 1073 /* 1074 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1075 * If the decision is made later to allow additional seals, care must be 1076 * taken below to ensure that the seals are properly set if the shmfd 1077 * already existed -- this currently assumes that only F_SEAL_SEAL can 1078 * be set and doesn't take further precautions to ensure the validity of 1079 * the seals being added with respect to current mappings. 1080 */ 1081 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1082 return (EINVAL); 1083 1084 pdp = td->td_proc->p_pd; 1085 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1086 1087 /* 1088 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1089 * by POSIX. We allow it to be unset here so that an in-kernel 1090 * interface may be written as a thin layer around shm, optionally not 1091 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1092 * in sys_shm_open() to keep this implementation compliant. 1093 */ 1094 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1095 if (error) 1096 return (error); 1097 1098 /* A SHM_ANON path pointer creates an anonymous object. */ 1099 if (userpath == SHM_ANON) { 1100 /* A read-only anonymous object is pointless. */ 1101 if ((flags & O_ACCMODE) == O_RDONLY) { 1102 fdclose(td, fp, fd); 1103 fdrop(fp, td); 1104 return (EINVAL); 1105 } 1106 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1107 shmfd->shm_seals = initial_seals; 1108 shmfd->shm_flags = shmflags; 1109 } else { 1110 error = shm_copyin_path(td, userpath, &path); 1111 if (error != 0) { 1112 fdclose(td, fp, fd); 1113 fdrop(fp, td); 1114 return (error); 1115 } 1116 1117 AUDIT_ARG_UPATH1_CANON(path); 1118 fnv = fnv_32_str(path, FNV1_32_INIT); 1119 sx_xlock(&shm_dict_lock); 1120 shmfd = shm_lookup(path, fnv); 1121 if (shmfd == NULL) { 1122 /* Object does not yet exist, create it if requested. */ 1123 if (flags & O_CREAT) { 1124#ifdef MAC 1125 error = mac_posixshm_check_create(td->td_ucred, 1126 path); 1127 if (error == 0) { 1128#endif 1129 shmfd = shm_alloc(td->td_ucred, cmode, 1130 largepage); 1131 shmfd->shm_seals = initial_seals; 1132 shmfd->shm_flags = shmflags; 1133 shm_insert(path, fnv, shmfd); 1134#ifdef MAC 1135 } 1136#endif 1137 } else { 1138 free(path, M_SHMFD); 1139 error = ENOENT; 1140 } 1141 } else { 1142 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1143 &shmfd->shm_mtx); 1144 1145 /* 1146 * kern_shm_open() likely shouldn't ever error out on 1147 * trying to set a seal that already exists, unlike 1148 * F_ADD_SEALS. This would break terribly as 1149 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1150 * historical behavior where the underlying file could 1151 * not be sealed. 1152 */ 1153 initial_seals &= ~shmfd->shm_seals; 1154 1155 /* 1156 * Object already exists, obtain a new 1157 * reference if requested and permitted. 1158 */ 1159 free(path, M_SHMFD); 1160 1161 /* 1162 * initial_seals can't set additional seals if we've 1163 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1164 * then we've already removed that one from 1165 * initial_seals. This is currently redundant as we 1166 * only allow setting F_SEAL_SEAL at creation time, but 1167 * it's cheap to check and decreases the effort required 1168 * to allow additional seals. 1169 */ 1170 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1171 initial_seals != 0) 1172 error = EPERM; 1173 else if ((flags & (O_CREAT | O_EXCL)) == 1174 (O_CREAT | O_EXCL)) 1175 error = EEXIST; 1176 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1177 error = EINVAL; 1178 else { 1179#ifdef MAC 1180 error = mac_posixshm_check_open(td->td_ucred, 1181 shmfd, FFLAGS(flags & O_ACCMODE)); 1182 if (error == 0) 1183#endif 1184 error = shm_access(shmfd, td->td_ucred, 1185 FFLAGS(flags & O_ACCMODE)); 1186 } 1187 1188 /* 1189 * Truncate the file back to zero length if 1190 * O_TRUNC was specified and the object was 1191 * opened with read/write. 1192 */ 1193 if (error == 0 && 1194 (flags & (O_ACCMODE | O_TRUNC)) == 1195 (O_RDWR | O_TRUNC)) { 1196 VM_OBJECT_WLOCK(shmfd->shm_object); 1197#ifdef MAC 1198 error = mac_posixshm_check_truncate( 1199 td->td_ucred, fp->f_cred, shmfd); 1200 if (error == 0) 1201#endif 1202 error = shm_dotruncate_locked(shmfd, 0, 1203 rl_cookie); 1204 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1205 } 1206 if (error == 0) { 1207 /* 1208 * Currently we only allow F_SEAL_SEAL to be 1209 * set initially. As noted above, this would 1210 * need to be reworked should that change. 1211 */ 1212 shmfd->shm_seals |= initial_seals; 1213 shm_hold(shmfd); 1214 } 1215 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 1216 &shmfd->shm_mtx); 1217 } 1218 sx_xunlock(&shm_dict_lock); 1219 1220 if (error) { 1221 fdclose(td, fp, fd); 1222 fdrop(fp, td); 1223 return (error); 1224 } 1225 } 1226 1227 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1228 1229 td->td_retval[0] = fd; 1230 fdrop(fp, td); 1231 1232 return (0); 1233} 1234 1235/* System calls. */ 1236#ifdef COMPAT_FREEBSD12 1237int 1238freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1239{ 1240 1241 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1242 uap->mode, NULL)); 1243} 1244#endif 1245 1246int 1247sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1248{ 1249 char *path; 1250 Fnv32_t fnv; 1251 int error; 1252 1253 error = shm_copyin_path(td, uap->path, &path); 1254 if (error != 0) 1255 return (error); 1256 1257 AUDIT_ARG_UPATH1_CANON(path); 1258 fnv = fnv_32_str(path, FNV1_32_INIT); 1259 sx_xlock(&shm_dict_lock); 1260 error = shm_remove(path, fnv, td->td_ucred); 1261 sx_xunlock(&shm_dict_lock); 1262 free(path, M_SHMFD); 1263 1264 return (error); 1265} 1266 1267int 1268sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1269{ 1270 char *path_from = NULL, *path_to = NULL; 1271 Fnv32_t fnv_from, fnv_to; 1272 struct shmfd *fd_from; 1273 struct shmfd *fd_to; 1274 int error; 1275 int flags; 1276 1277 flags = uap->flags; 1278 AUDIT_ARG_FFLAGS(flags); 1279 1280 /* 1281 * Make sure the user passed only valid flags. 1282 * If you add a new flag, please add a new term here. 1283 */ 1284 if ((flags & ~( 1285 SHM_RENAME_NOREPLACE | 1286 SHM_RENAME_EXCHANGE 1287 )) != 0) { 1288 error = EINVAL; 1289 goto out; 1290 } 1291 1292 /* 1293 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1294 * force the user to choose one or the other. 1295 */ 1296 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1297 (flags & SHM_RENAME_EXCHANGE) != 0) { 1298 error = EINVAL; 1299 goto out; 1300 } 1301 1302 /* Renaming to or from anonymous makes no sense */ 1303 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1304 error = EINVAL; 1305 goto out; 1306 } 1307 1308 error = shm_copyin_path(td, uap->path_from, &path_from); 1309 if (error != 0) 1310 goto out; 1311 1312 error = shm_copyin_path(td, uap->path_to, &path_to); 1313 if (error != 0) 1314 goto out; 1315 1316 AUDIT_ARG_UPATH1_CANON(path_from); 1317 AUDIT_ARG_UPATH2_CANON(path_to); 1318 1319 /* Rename with from/to equal is a no-op */ 1320 if (strcmp(path_from, path_to) == 0) 1321 goto out; 1322 1323 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1324 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1325 1326 sx_xlock(&shm_dict_lock); 1327 1328 fd_from = shm_lookup(path_from, fnv_from); 1329 if (fd_from == NULL) { 1330 error = ENOENT; 1331 goto out_locked; 1332 } 1333 1334 fd_to = shm_lookup(path_to, fnv_to); 1335 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1336 error = EEXIST; 1337 goto out_locked; 1338 } 1339 1340 /* 1341 * Unconditionally prevents shm_remove from invalidating the 'from' 1342 * shm's state. 1343 */ 1344 shm_hold(fd_from); 1345 error = shm_remove(path_from, fnv_from, td->td_ucred); 1346 1347 /* 1348 * One of my assumptions failed if ENOENT (e.g. locking didn't 1349 * protect us) 1350 */ 1351 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1352 path_from)); 1353 if (error != 0) { 1354 shm_drop(fd_from); 1355 goto out_locked; 1356 } 1357 1358 /* 1359 * If we are exchanging, we need to ensure the shm_remove below 1360 * doesn't invalidate the dest shm's state. 1361 */ 1362 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1363 shm_hold(fd_to); 1364 1365 /* 1366 * NOTE: if path_to is not already in the hash, c'est la vie; 1367 * it simply means we have nothing already at path_to to unlink. 1368 * That is the ENOENT case. 1369 * 1370 * If we somehow don't have access to unlink this guy, but 1371 * did for the shm at path_from, then relink the shm to path_from 1372 * and abort with EACCES. 1373 * 1374 * All other errors: that is weird; let's relink and abort the 1375 * operation. 1376 */ 1377 error = shm_remove(path_to, fnv_to, td->td_ucred); 1378 if (error != 0 && error != ENOENT) { 1379 shm_insert(path_from, fnv_from, fd_from); 1380 shm_drop(fd_from); 1381 /* Don't free path_from now, since the hash references it */ 1382 path_from = NULL; 1383 goto out_locked; 1384 } 1385 1386 error = 0; 1387 1388 shm_insert(path_to, fnv_to, fd_from); 1389 1390 /* Don't free path_to now, since the hash references it */ 1391 path_to = NULL; 1392 1393 /* We kept a ref when we removed, and incremented again in insert */ 1394 shm_drop(fd_from); 1395 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1396 fd_from->shm_refs)); 1397 1398 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1399 shm_insert(path_from, fnv_from, fd_to); 1400 path_from = NULL; 1401 shm_drop(fd_to); 1402 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1403 fd_to->shm_refs)); 1404 } 1405 1406out_locked: 1407 sx_xunlock(&shm_dict_lock); 1408 1409out: 1410 free(path_from, M_SHMFD); 1411 free(path_to, M_SHMFD); 1412 return (error); 1413} 1414 1415static int 1416shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1417 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1418 vm_ooffset_t foff, struct thread *td) 1419{ 1420 struct vmspace *vms; 1421 vm_map_entry_t next_entry, prev_entry; 1422 vm_offset_t align, mask, maxaddr; 1423 int docow, error, rv, try; 1424 bool curmap; 1425 1426 if (shmfd->shm_lp_psind == 0) 1427 return (EINVAL); 1428 1429 /* MAP_PRIVATE is disabled */ 1430 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1431 MAP_NOCORE | 1432#ifdef MAP_32BIT 1433 MAP_32BIT | 1434#endif 1435 MAP_ALIGNMENT_MASK)) != 0) 1436 return (EINVAL); 1437 1438 vms = td->td_proc->p_vmspace; 1439 curmap = map == &vms->vm_map; 1440 if (curmap) { 1441 error = kern_mmap_racct_check(td, map, size); 1442 if (error != 0) 1443 return (error); 1444 } 1445 1446 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1447 docow |= MAP_INHERIT_SHARE; 1448 if ((flags & MAP_NOCORE) != 0) 1449 docow |= MAP_DISABLE_COREDUMP; 1450 1451 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1452 if ((foff & mask) != 0) 1453 return (EINVAL); 1454 maxaddr = vm_map_max(map); 1455#ifdef MAP_32BIT 1456 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1457 maxaddr = MAP_32BIT_MAX_ADDR; 1458#endif 1459 if (size == 0 || (size & mask) != 0 || 1460 (*addr != 0 && ((*addr & mask) != 0 || 1461 *addr + size < *addr || *addr + size > maxaddr))) 1462 return (EINVAL); 1463 1464 align = flags & MAP_ALIGNMENT_MASK; 1465 if (align == 0) { 1466 align = pagesizes[shmfd->shm_lp_psind]; 1467 } else if (align == MAP_ALIGNED_SUPER) { 1468 if (shmfd->shm_lp_psind != 1) 1469 return (EINVAL); 1470 align = pagesizes[1]; 1471 } else { 1472 align >>= MAP_ALIGNMENT_SHIFT; 1473 align = 1ULL << align; 1474 /* Also handles overflow. */ 1475 if (align < pagesizes[shmfd->shm_lp_psind]) 1476 return (EINVAL); 1477 } 1478 1479 vm_map_lock(map); 1480 if ((flags & MAP_FIXED) == 0) { 1481 try = 1; 1482 if (curmap && (*addr == 0 || 1483 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1484 *addr < round_page((vm_offset_t)vms->vm_daddr + 1485 lim_max(td, RLIMIT_DATA))))) { 1486 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1487 lim_max(td, RLIMIT_DATA), 1488 pagesizes[shmfd->shm_lp_psind]); 1489 } 1490again: 1491 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1492 if (rv != KERN_SUCCESS) { 1493 if (try == 1) { 1494 try = 2; 1495 *addr = vm_map_min(map); 1496 if ((*addr & mask) != 0) 1497 *addr = (*addr + mask) & mask; 1498 goto again; 1499 } 1500 goto fail1; 1501 } 1502 } else if ((flags & MAP_EXCL) == 0) { 1503 rv = vm_map_delete(map, *addr, *addr + size); 1504 if (rv != KERN_SUCCESS) 1505 goto fail1; 1506 } else { 1507 error = ENOSPC; 1508 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1509 goto fail; 1510 next_entry = vm_map_entry_succ(prev_entry); 1511 if (next_entry->start < *addr + size) 1512 goto fail; 1513 } 1514 1515 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1516 prot, max_prot, docow); 1517fail1: 1518 error = vm_mmap_to_errno(rv); 1519fail: 1520 vm_map_unlock(map); 1521 return (error); 1522} 1523 1524static int 1525shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1526 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1527 vm_ooffset_t foff, struct thread *td) 1528{ 1529 struct shmfd *shmfd; 1530 vm_prot_t maxprot; 1531 int error; 1532 bool writecnt; 1533 void *rl_cookie; 1534 1535 shmfd = fp->f_data; 1536 maxprot = VM_PROT_NONE; 1537 1538 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1539 &shmfd->shm_mtx); 1540 /* FREAD should always be set. */ 1541 if ((fp->f_flag & FREAD) != 0) 1542 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1543 1544 /* 1545 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1546 * mapping with a write seal applied. Private mappings are always 1547 * writeable. 1548 */ 1549 if ((flags & MAP_SHARED) == 0) { 1550 cap_maxprot |= VM_PROT_WRITE; 1551 maxprot |= VM_PROT_WRITE; 1552 writecnt = false; 1553 } else { 1554 if ((fp->f_flag & FWRITE) != 0 && 1555 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1556 maxprot |= VM_PROT_WRITE; 1557 1558 /* 1559 * Any mappings from a writable descriptor may be upgraded to 1560 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1561 * applied between the open and subsequent mmap(2). We want to 1562 * reject application of a write seal as long as any such 1563 * mapping exists so that the seal cannot be trivially bypassed. 1564 */ 1565 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1566 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1567 error = EACCES; 1568 goto out; 1569 } 1570 } 1571 maxprot &= cap_maxprot; 1572 1573 /* See comment in vn_mmap(). */ 1574 if ( 1575#ifdef _LP64 1576 objsize > OFF_MAX || 1577#endif 1578 foff > OFF_MAX - objsize) { 1579 error = EINVAL; 1580 goto out; 1581 } 1582 1583#ifdef MAC 1584 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1585 if (error != 0) 1586 goto out; 1587#endif 1588 1589 mtx_lock(&shm_timestamp_lock); 1590 vfs_timestamp(&shmfd->shm_atime); 1591 mtx_unlock(&shm_timestamp_lock); 1592 vm_object_reference(shmfd->shm_object); 1593 1594 if (shm_largepage(shmfd)) { 1595 writecnt = false; 1596 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1597 maxprot, flags, foff, td); 1598 } else { 1599 if (writecnt) { 1600 vm_pager_update_writecount(shmfd->shm_object, 0, 1601 objsize); 1602 } 1603 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1604 shmfd->shm_object, foff, writecnt, td); 1605 } 1606 if (error != 0) { 1607 if (writecnt) 1608 vm_pager_release_writecount(shmfd->shm_object, 0, 1609 objsize); 1610 vm_object_deallocate(shmfd->shm_object); 1611 } 1612out: 1613 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1614 return (error); 1615} 1616 1617static int 1618shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1619 struct thread *td) 1620{ 1621 struct shmfd *shmfd; 1622 int error; 1623 1624 error = 0; 1625 shmfd = fp->f_data; 1626 mtx_lock(&shm_timestamp_lock); 1627 /* 1628 * SUSv4 says that x bits of permission need not be affected. 1629 * Be consistent with our shm_open there. 1630 */ 1631#ifdef MAC 1632 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1633 if (error != 0) 1634 goto out; 1635#endif 1636 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1637 VADMIN, active_cred); 1638 if (error != 0) 1639 goto out; 1640 shmfd->shm_mode = mode & ACCESSPERMS; 1641out: 1642 mtx_unlock(&shm_timestamp_lock); 1643 return (error); 1644} 1645 1646static int 1647shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1648 struct thread *td) 1649{ 1650 struct shmfd *shmfd; 1651 int error; 1652 1653 error = 0; 1654 shmfd = fp->f_data; 1655 mtx_lock(&shm_timestamp_lock); 1656#ifdef MAC 1657 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1658 if (error != 0) 1659 goto out; 1660#endif 1661 if (uid == (uid_t)-1) 1662 uid = shmfd->shm_uid; 1663 if (gid == (gid_t)-1) 1664 gid = shmfd->shm_gid; 1665 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1666 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1667 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1668 goto out; 1669 shmfd->shm_uid = uid; 1670 shmfd->shm_gid = gid; 1671out: 1672 mtx_unlock(&shm_timestamp_lock); 1673 return (error); 1674} 1675 1676/* 1677 * Helper routines to allow the backing object of a shared memory file 1678 * descriptor to be mapped in the kernel. 1679 */ 1680int 1681shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1682{ 1683 struct shmfd *shmfd; 1684 vm_offset_t kva, ofs; 1685 vm_object_t obj; 1686 int rv; 1687 1688 if (fp->f_type != DTYPE_SHM) 1689 return (EINVAL); 1690 shmfd = fp->f_data; 1691 obj = shmfd->shm_object; 1692 VM_OBJECT_WLOCK(obj); 1693 /* 1694 * XXXRW: This validation is probably insufficient, and subject to 1695 * sign errors. It should be fixed. 1696 */ 1697 if (offset >= shmfd->shm_size || 1698 offset + size > round_page(shmfd->shm_size)) { 1699 VM_OBJECT_WUNLOCK(obj); 1700 return (EINVAL); 1701 } 1702 1703 shmfd->shm_kmappings++; 1704 vm_object_reference_locked(obj); 1705 VM_OBJECT_WUNLOCK(obj); 1706 1707 /* Map the object into the kernel_map and wire it. */ 1708 kva = vm_map_min(kernel_map); 1709 ofs = offset & PAGE_MASK; 1710 offset = trunc_page(offset); 1711 size = round_page(size + ofs); 1712 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1713 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1714 VM_PROT_READ | VM_PROT_WRITE, 0); 1715 if (rv == KERN_SUCCESS) { 1716 rv = vm_map_wire(kernel_map, kva, kva + size, 1717 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1718 if (rv == KERN_SUCCESS) { 1719 *memp = (void *)(kva + ofs); 1720 return (0); 1721 } 1722 vm_map_remove(kernel_map, kva, kva + size); 1723 } else 1724 vm_object_deallocate(obj); 1725 1726 /* On failure, drop our mapping reference. */ 1727 VM_OBJECT_WLOCK(obj); 1728 shmfd->shm_kmappings--; 1729 VM_OBJECT_WUNLOCK(obj); 1730 1731 return (vm_mmap_to_errno(rv)); 1732} 1733 1734/* 1735 * We require the caller to unmap the entire entry. This allows us to 1736 * safely decrement shm_kmappings when a mapping is removed. 1737 */ 1738int 1739shm_unmap(struct file *fp, void *mem, size_t size) 1740{ 1741 struct shmfd *shmfd; 1742 vm_map_entry_t entry; 1743 vm_offset_t kva, ofs; 1744 vm_object_t obj; 1745 vm_pindex_t pindex; 1746 vm_prot_t prot; 1747 boolean_t wired; 1748 vm_map_t map; 1749 int rv; 1750 1751 if (fp->f_type != DTYPE_SHM) 1752 return (EINVAL); 1753 shmfd = fp->f_data; 1754 kva = (vm_offset_t)mem; 1755 ofs = kva & PAGE_MASK; 1756 kva = trunc_page(kva); 1757 size = round_page(size + ofs); 1758 map = kernel_map; 1759 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1760 &obj, &pindex, &prot, &wired); 1761 if (rv != KERN_SUCCESS) 1762 return (EINVAL); 1763 if (entry->start != kva || entry->end != kva + size) { 1764 vm_map_lookup_done(map, entry); 1765 return (EINVAL); 1766 } 1767 vm_map_lookup_done(map, entry); 1768 if (obj != shmfd->shm_object) 1769 return (EINVAL); 1770 vm_map_remove(map, kva, kva + size); 1771 VM_OBJECT_WLOCK(obj); 1772 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1773 shmfd->shm_kmappings--; 1774 VM_OBJECT_WUNLOCK(obj); 1775 return (0); 1776} 1777 1778static int 1779shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1780{ 1781 const char *path, *pr_path; 1782 size_t pr_pathlen; 1783 bool visible; 1784 1785 sx_assert(&shm_dict_lock, SA_LOCKED); 1786 kif->kf_type = KF_TYPE_SHM; 1787 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1788 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1789 if (shmfd->shm_path != NULL) { 1790 if (shmfd->shm_path != NULL) { 1791 path = shmfd->shm_path; 1792 pr_path = curthread->td_ucred->cr_prison->pr_path; 1793 if (strcmp(pr_path, "/") != 0) { 1794 /* Return the jail-rooted pathname. */ 1795 pr_pathlen = strlen(pr_path); 1796 visible = strncmp(path, pr_path, pr_pathlen) 1797 == 0 && path[pr_pathlen] == '/'; 1798 if (list && !visible) 1799 return (EPERM); 1800 if (visible) 1801 path += pr_pathlen; 1802 } 1803 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1804 } 1805 } 1806 return (0); 1807} 1808 1809static int 1810shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1811 struct filedesc *fdp __unused) 1812{ 1813 int res; 1814 1815 sx_slock(&shm_dict_lock); 1816 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1817 sx_sunlock(&shm_dict_lock); 1818 return (res); 1819} 1820 1821static int 1822shm_add_seals(struct file *fp, int seals) 1823{ 1824 struct shmfd *shmfd; 1825 void *rl_cookie; 1826 vm_ooffset_t writemappings; 1827 int error, nseals; 1828 1829 error = 0; 1830 shmfd = fp->f_data; 1831 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1832 &shmfd->shm_mtx); 1833 1834 /* Even already-set seals should result in EPERM. */ 1835 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1836 error = EPERM; 1837 goto out; 1838 } 1839 nseals = seals & ~shmfd->shm_seals; 1840 if ((nseals & F_SEAL_WRITE) != 0) { 1841 if (shm_largepage(shmfd)) { 1842 error = ENOTSUP; 1843 goto out; 1844 } 1845 1846 /* 1847 * The rangelock above prevents writable mappings from being 1848 * added after we've started applying seals. The RLOCK here 1849 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1850 * writemappings will be done without a rangelock. 1851 */ 1852 VM_OBJECT_RLOCK(shmfd->shm_object); 1853 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1854 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1855 /* kmappings are also writable */ 1856 if (writemappings > 0) { 1857 error = EBUSY; 1858 goto out; 1859 } 1860 } 1861 shmfd->shm_seals |= nseals; 1862out: 1863 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1864 return (error); 1865} 1866 1867static int 1868shm_get_seals(struct file *fp, int *seals) 1869{ 1870 struct shmfd *shmfd; 1871 1872 shmfd = fp->f_data; 1873 *seals = shmfd->shm_seals; 1874 return (0); 1875} 1876 1877static int 1878shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 1879{ 1880 void *rl_cookie; 1881 struct shmfd *shmfd; 1882 size_t size; 1883 int error; 1884 1885 /* This assumes that the caller already checked for overflow. */ 1886 error = 0; 1887 shmfd = fp->f_data; 1888 size = offset + len; 1889 1890 /* 1891 * Just grab the rangelock for the range that we may be attempting to 1892 * grow, rather than blocking read/write for regions we won't be 1893 * touching while this (potential) resize is in progress. Other 1894 * attempts to resize the shmfd will have to take a write lock from 0 to 1895 * OFF_MAX, so this being potentially beyond the current usable range of 1896 * the shmfd is not necessarily a concern. If other mechanisms are 1897 * added to grow a shmfd, this may need to be re-evaluated. 1898 */ 1899 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 1900 &shmfd->shm_mtx); 1901 if (size > shmfd->shm_size) 1902 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 1903 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1904 /* Translate to posix_fallocate(2) return value as needed. */ 1905 if (error == ENOMEM) 1906 error = ENOSPC; 1907 return (error); 1908} 1909 1910static int 1911sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1912{ 1913 struct shm_mapping *shmm; 1914 struct sbuf sb; 1915 struct kinfo_file kif; 1916 u_long i; 1917 ssize_t curlen; 1918 int error, error2; 1919 1920 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1921 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1922 curlen = 0; 1923 error = 0; 1924 sx_slock(&shm_dict_lock); 1925 for (i = 0; i < shm_hash + 1; i++) { 1926 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1927 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1928 &kif, true); 1929 if (error == EPERM) 1930 continue; 1931 if (error != 0) 1932 break; 1933 pack_kinfo(&kif); 1934 if (req->oldptr != NULL && 1935 kif.kf_structsize + curlen > req->oldlen) 1936 break; 1937 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1938 0 : ENOMEM; 1939 if (error != 0) 1940 break; 1941 curlen += kif.kf_structsize; 1942 } 1943 } 1944 sx_sunlock(&shm_dict_lock); 1945 error2 = sbuf_finish(&sb); 1946 sbuf_delete(&sb); 1947 return (error != 0 ? error : error2); 1948} 1949 1950SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1951 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1952 NULL, 0, sysctl_posix_shm_list, "", 1953 "POSIX SHM list"); 1954 1955int 1956kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1957 struct filecaps *caps) 1958{ 1959 1960 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1961} 1962 1963/* 1964 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1965 * caller, and libc will enforce it for the traditional shm_open() call. This 1966 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1967 * interface also includes a 'name' argument that is currently unused, but could 1968 * potentially be exported later via some interface for debugging purposes. 1969 * From the kernel's perspective, it is optional. Individual consumers like 1970 * memfd_create() may require it in order to be compatible with other systems 1971 * implementing the same function. 1972 */ 1973int 1974sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1975{ 1976 1977 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1978 uap->shmflags, NULL, uap->name)); 1979} 1980