Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/uipc_shm.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 5 * Copyright 2020 The FreeBSD Foundation 6 * All rights reserved. 7 * 8 * Portions of this software were developed by BAE Systems, the University of 9 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 10 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 11 * Computing (TC) research program. 12 * 13 * Portions of this software were developed by Konstantin Belousov 14 * under sponsorship from the FreeBSD Foundation. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38 /* 39 * Support for shared swap-backed anonymous memory objects via 40 * shm_open(2), shm_rename(2), and shm_unlink(2). 41 * While most of the implementation is here, vm_mmap.c contains 42 * mapping logic changes. 43 * 44 * posixshmcontrol(1) allows users to inspect the state of the memory 45 * objects. Per-uid swap resource limit controls total amount of 46 * memory that user can consume for anonymous objects, including 47 * shared. 48 */ 49 50 #include <sys/cdefs.h> 51 __FBSDID("$FreeBSD$"); 52 53 #include "opt_capsicum.h" 54 #include "opt_ktrace.h" 55 56 #include <sys/param.h> 57 #include <sys/capsicum.h> 58 #include <sys/conf.h> 59 #include <sys/fcntl.h> 60 #include <sys/file.h> 61 #include <sys/filedesc.h> 62 #include <sys/filio.h> 63 #include <sys/fnv_hash.h> 64 #include <sys/kernel.h> 65 #include <sys/limits.h> 66 #include <sys/uio.h> 67 #include <sys/signal.h> 68 #include <sys/jail.h> 69 #include <sys/ktrace.h> 70 #include <sys/lock.h> 71 #include <sys/malloc.h> 72 #include <sys/mman.h> 73 #include <sys/mutex.h> 74 #include <sys/priv.h> 75 #include <sys/proc.h> 76 #include <sys/refcount.h> 77 #include <sys/resourcevar.h> 78 #include <sys/rwlock.h> 79 #include <sys/sbuf.h> 80 #include <sys/stat.h> 81 #include <sys/syscallsubr.h> 82 #include <sys/sysctl.h> 83 #include <sys/sysproto.h> 84 #include <sys/systm.h> 85 #include <sys/sx.h> 86 #include <sys/time.h> 87 #include <sys/vmmeter.h> 88 #include <sys/vnode.h> 89 #include <sys/unistd.h> 90 #include <sys/user.h> 91 92 #include <security/audit/audit.h> 93 #include <security/mac/mac_framework.h> 94 95 #include <vm/vm.h> 96 #include <vm/vm_param.h> 97 #include <vm/pmap.h> 98 #include <vm/vm_extern.h> 99 #include <vm/vm_map.h> 100 #include <vm/vm_kern.h> 101 #include <vm/vm_object.h> 102 #include <vm/vm_page.h> 103 #include <vm/vm_pageout.h> 104 #include <vm/vm_pager.h> 105 #include <vm/swap_pager.h> 106 107 struct shm_mapping { 108 char *sm_path; 109 Fnv32_t sm_fnv; 110 struct shmfd *sm_shmfd; 111 LIST_ENTRY(shm_mapping) sm_link; 112 }; 113 114 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 115 static LIST_HEAD(, shm_mapping) *shm_dictionary; 116 static struct sx shm_dict_lock; 117 static struct mtx shm_timestamp_lock; 118 static u_long shm_hash; 119 static struct unrhdr64 shm_ino_unr; 120 static dev_t shm_dev_ino; 121 122 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 123 124 static void shm_init(void *arg); 125 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 126 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 127 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 128 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 129 void *rl_cookie); 130 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 131 void *rl_cookie); 132 static int shm_copyin_path(struct thread *td, const char *userpath_in, 133 char **path_out); 134 135 static fo_rdwr_t shm_read; 136 static fo_rdwr_t shm_write; 137 static fo_truncate_t shm_truncate; 138 static fo_ioctl_t shm_ioctl; 139 static fo_stat_t shm_stat; 140 static fo_close_t shm_close; 141 static fo_chmod_t shm_chmod; 142 static fo_chown_t shm_chown; 143 static fo_seek_t shm_seek; 144 static fo_fill_kinfo_t shm_fill_kinfo; 145 static fo_mmap_t shm_mmap; 146 static fo_get_seals_t shm_get_seals; 147 static fo_add_seals_t shm_add_seals; 148 static fo_fallocate_t shm_fallocate; 149 150 /* File descriptor operations. */ 151 struct 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 }; 171 172 FEATURE(posix_shm, "POSIX shared memory"); 173 174 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 175 ""); 176 177 static int largepage_reclaim_tries = 1; 178 SYSCTL_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"); 181 182 static int 183 uiomove_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); 228 229 found: 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 } 238 239 int 240 uiomove_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 } 259 260 static u_long count_largepages[MAXPAGESIZES]; 261 262 static int 263 shm_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 __diagused; 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 } 286 287 static boolean_t 288 shm_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 } 306 307 static void 308 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 309 vm_ooffset_t foff, struct ucred *cred) 310 { 311 } 312 313 static void 314 shm_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 } 329 330 static 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 }; 336 337 bool 338 shm_largepage(struct shmfd *shmfd) 339 { 340 return (shmfd->shm_object->type == OBJT_PHYS); 341 } 342 343 static int 344 shm_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 } 383 384 static int 385 shm_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 } 406 407 static int 408 shm_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 } 463 464 static int 465 shm_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 } 481 482 int 483 shm_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 } 535 536 static int 537 shm_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 } 578 579 static int 580 shm_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 } 590 591 static int 592 shm_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; 621 622 out: 623 if (error != 0) 624 free(path, M_SHMFD); 625 626 return (error); 627 } 628 629 static int 630 shm_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); 664 retry: 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 } 730 731 static int 732 shm_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; 737 vm_pindex_t oldobjsz __unused; 738 int aflags, error, i, psind, try; 739 740 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 741 object = shmfd->shm_object; 742 VM_OBJECT_ASSERT_WLOCKED(object); 743 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 744 745 oldobjsz = object->size; 746 newobjsz = OFF_TO_IDX(length); 747 if (length == shmfd->shm_size) 748 return (0); 749 psind = shmfd->shm_lp_psind; 750 if (psind == 0 && length != 0) 751 return (EINVAL); 752 if ((length & (pagesizes[psind] - 1)) != 0) 753 return (EINVAL); 754 755 if (length < shmfd->shm_size) { 756 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 757 return (EPERM); 758 if (shmfd->shm_kmappings > 0) 759 return (EBUSY); 760 return (ENOTSUP); /* Pages are unmanaged. */ 761 #if 0 762 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 763 object->size = newobjsz; 764 shmfd->shm_size = length; 765 return (0); 766 #endif 767 } 768 769 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 770 return (EPERM); 771 772 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 773 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 774 aflags |= VM_ALLOC_WAITFAIL; 775 try = 0; 776 777 /* 778 * Extend shmfd and object, keeping all already fully 779 * allocated large pages intact even on error, because dropped 780 * object lock might allowed mapping of them. 781 */ 782 while (object->size < newobjsz) { 783 m = vm_page_alloc_contig(object, object->size, aflags, 784 pagesizes[psind] / PAGE_SIZE, 0, ~0, 785 pagesizes[psind], 0, 786 VM_MEMATTR_DEFAULT); 787 if (m == NULL) { 788 VM_OBJECT_WUNLOCK(object); 789 if (shmfd->shm_lp_alloc_policy == 790 SHM_LARGEPAGE_ALLOC_NOWAIT || 791 (shmfd->shm_lp_alloc_policy == 792 SHM_LARGEPAGE_ALLOC_DEFAULT && 793 try >= largepage_reclaim_tries)) { 794 VM_OBJECT_WLOCK(object); 795 return (ENOMEM); 796 } 797 error = vm_page_reclaim_contig(aflags, 798 pagesizes[psind] / PAGE_SIZE, 0, ~0, 799 pagesizes[psind], 0) ? 0 : 800 vm_wait_intr(object); 801 if (error != 0) { 802 VM_OBJECT_WLOCK(object); 803 return (error); 804 } 805 try++; 806 VM_OBJECT_WLOCK(object); 807 continue; 808 } 809 try = 0; 810 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 811 if ((m[i].flags & PG_ZERO) == 0) 812 pmap_zero_page(&m[i]); 813 vm_page_valid(&m[i]); 814 vm_page_xunbusy(&m[i]); 815 } 816 object->size += OFF_TO_IDX(pagesizes[psind]); 817 shmfd->shm_size += pagesizes[psind]; 818 atomic_add_long(&count_largepages[psind], 1); 819 vm_wire_add(atop(pagesizes[psind])); 820 } 821 return (0); 822 } 823 824 static int 825 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 826 { 827 int error; 828 829 VM_OBJECT_WLOCK(shmfd->shm_object); 830 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 831 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 832 rl_cookie); 833 VM_OBJECT_WUNLOCK(shmfd->shm_object); 834 return (error); 835 } 836 837 int 838 shm_dotruncate(struct shmfd *shmfd, off_t length) 839 { 840 void *rl_cookie; 841 int error; 842 843 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 844 &shmfd->shm_mtx); 845 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 846 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 847 return (error); 848 } 849 850 /* 851 * shmfd object management including creation and reference counting 852 * routines. 853 */ 854 struct shmfd * 855 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 856 { 857 struct shmfd *shmfd; 858 859 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 860 shmfd->shm_size = 0; 861 shmfd->shm_uid = ucred->cr_uid; 862 shmfd->shm_gid = ucred->cr_gid; 863 shmfd->shm_mode = mode; 864 if (largepage) { 865 shmfd->shm_object = phys_pager_allocate(NULL, 866 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 867 VM_PROT_DEFAULT, 0, ucred); 868 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 869 } else { 870 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 871 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 872 } 873 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 874 vfs_timestamp(&shmfd->shm_birthtime); 875 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 876 shmfd->shm_birthtime; 877 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 878 refcount_init(&shmfd->shm_refs, 1); 879 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 880 rangelock_init(&shmfd->shm_rl); 881 #ifdef MAC 882 mac_posixshm_init(shmfd); 883 mac_posixshm_create(ucred, shmfd); 884 #endif 885 886 return (shmfd); 887 } 888 889 struct shmfd * 890 shm_hold(struct shmfd *shmfd) 891 { 892 893 refcount_acquire(&shmfd->shm_refs); 894 return (shmfd); 895 } 896 897 void 898 shm_drop(struct shmfd *shmfd) 899 { 900 901 if (refcount_release(&shmfd->shm_refs)) { 902 #ifdef MAC 903 mac_posixshm_destroy(shmfd); 904 #endif 905 rangelock_destroy(&shmfd->shm_rl); 906 mtx_destroy(&shmfd->shm_mtx); 907 vm_object_deallocate(shmfd->shm_object); 908 free(shmfd, M_SHMFD); 909 } 910 } 911 912 /* 913 * Determine if the credentials have sufficient permissions for a 914 * specified combination of FREAD and FWRITE. 915 */ 916 int 917 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 918 { 919 accmode_t accmode; 920 int error; 921 922 accmode = 0; 923 if (flags & FREAD) 924 accmode |= VREAD; 925 if (flags & FWRITE) 926 accmode |= VWRITE; 927 mtx_lock(&shm_timestamp_lock); 928 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 929 accmode, ucred); 930 mtx_unlock(&shm_timestamp_lock); 931 return (error); 932 } 933 934 static void 935 shm_init(void *arg) 936 { 937 char name[32]; 938 int i; 939 940 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 941 sx_init(&shm_dict_lock, "shm dictionary"); 942 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 943 new_unrhdr64(&shm_ino_unr, 1); 944 shm_dev_ino = devfs_alloc_cdp_inode(); 945 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 946 947 for (i = 1; i < MAXPAGESIZES; i++) { 948 if (pagesizes[i] == 0) 949 break; 950 #define M (1024 * 1024) 951 #define G (1024 * M) 952 if (pagesizes[i] >= G) 953 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 954 else if (pagesizes[i] >= M) 955 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 956 else 957 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 958 #undef G 959 #undef M 960 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 961 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 962 "number of non-transient largepages allocated"); 963 } 964 } 965 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 966 967 /* 968 * Dictionary management. We maintain an in-kernel dictionary to map 969 * paths to shmfd objects. We use the FNV hash on the path to store 970 * the mappings in a hash table. 971 */ 972 static struct shmfd * 973 shm_lookup(char *path, Fnv32_t fnv) 974 { 975 struct shm_mapping *map; 976 977 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 978 if (map->sm_fnv != fnv) 979 continue; 980 if (strcmp(map->sm_path, path) == 0) 981 return (map->sm_shmfd); 982 } 983 984 return (NULL); 985 } 986 987 static void 988 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 989 { 990 struct shm_mapping *map; 991 992 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 993 map->sm_path = path; 994 map->sm_fnv = fnv; 995 map->sm_shmfd = shm_hold(shmfd); 996 shmfd->shm_path = path; 997 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 998 } 999 1000 static int 1001 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1002 { 1003 struct shm_mapping *map; 1004 int error; 1005 1006 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1007 if (map->sm_fnv != fnv) 1008 continue; 1009 if (strcmp(map->sm_path, path) == 0) { 1010 #ifdef MAC 1011 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1012 if (error) 1013 return (error); 1014 #endif 1015 error = shm_access(map->sm_shmfd, ucred, 1016 FREAD | FWRITE); 1017 if (error) 1018 return (error); 1019 map->sm_shmfd->shm_path = NULL; 1020 LIST_REMOVE(map, sm_link); 1021 shm_drop(map->sm_shmfd); 1022 free(map->sm_path, M_SHMFD); 1023 free(map, M_SHMFD); 1024 return (0); 1025 } 1026 } 1027 1028 return (ENOENT); 1029 } 1030 1031 int 1032 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1033 int shmflags, struct filecaps *fcaps, const char *name __unused) 1034 { 1035 struct pwddesc *pdp; 1036 struct shmfd *shmfd; 1037 struct file *fp; 1038 char *path; 1039 void *rl_cookie; 1040 Fnv32_t fnv; 1041 mode_t cmode; 1042 int error, fd, initial_seals; 1043 bool largepage; 1044 1045 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1046 SHM_LARGEPAGE)) != 0) 1047 return (EINVAL); 1048 1049 initial_seals = F_SEAL_SEAL; 1050 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1051 initial_seals &= ~F_SEAL_SEAL; 1052 1053 #ifdef CAPABILITY_MODE 1054 /* 1055 * shm_open(2) is only allowed for anonymous objects. 1056 */ 1057 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1058 return (ECAPMODE); 1059 #endif 1060 1061 AUDIT_ARG_FFLAGS(flags); 1062 AUDIT_ARG_MODE(mode); 1063 1064 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1065 return (EINVAL); 1066 1067 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1068 return (EINVAL); 1069 1070 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1071 if (largepage && !PMAP_HAS_LARGEPAGES) 1072 return (ENOTTY); 1073 1074 /* 1075 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1076 * If the decision is made later to allow additional seals, care must be 1077 * taken below to ensure that the seals are properly set if the shmfd 1078 * already existed -- this currently assumes that only F_SEAL_SEAL can 1079 * be set and doesn't take further precautions to ensure the validity of 1080 * the seals being added with respect to current mappings. 1081 */ 1082 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1083 return (EINVAL); 1084 1085 pdp = td->td_proc->p_pd; 1086 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1087 1088 /* 1089 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1090 * by POSIX. We allow it to be unset here so that an in-kernel 1091 * interface may be written as a thin layer around shm, optionally not 1092 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1093 * in sys_shm_open() to keep this implementation compliant. 1094 */ 1095 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1096 if (error) 1097 return (error); 1098 1099 /* A SHM_ANON path pointer creates an anonymous object. */ 1100 if (userpath == SHM_ANON) { 1101 /* A read-only anonymous object is pointless. */ 1102 if ((flags & O_ACCMODE) == O_RDONLY) { 1103 fdclose(td, fp, fd); 1104 fdrop(fp, td); 1105 return (EINVAL); 1106 } 1107 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1108 shmfd->shm_seals = initial_seals; 1109 shmfd->shm_flags = shmflags; 1110 } else { 1111 error = shm_copyin_path(td, userpath, &path); 1112 if (error != 0) { 1113 fdclose(td, fp, fd); 1114 fdrop(fp, td); 1115 return (error); 1116 } 1117 1118 AUDIT_ARG_UPATH1_CANON(path); 1119 fnv = fnv_32_str(path, FNV1_32_INIT); 1120 sx_xlock(&shm_dict_lock); 1121 shmfd = shm_lookup(path, fnv); 1122 if (shmfd == NULL) { 1123 /* Object does not yet exist, create it if requested. */ 1124 if (flags & O_CREAT) { 1125 #ifdef MAC 1126 error = mac_posixshm_check_create(td->td_ucred, 1127 path); 1128 if (error == 0) { 1129 #endif 1130 shmfd = shm_alloc(td->td_ucred, cmode, 1131 largepage); 1132 shmfd->shm_seals = initial_seals; 1133 shmfd->shm_flags = shmflags; 1134 shm_insert(path, fnv, shmfd); 1135 #ifdef MAC 1136 } 1137 #endif 1138 } else { 1139 free(path, M_SHMFD); 1140 error = ENOENT; 1141 } 1142 } else { 1143 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1144 &shmfd->shm_mtx); 1145 1146 /* 1147 * kern_shm_open() likely shouldn't ever error out on 1148 * trying to set a seal that already exists, unlike 1149 * F_ADD_SEALS. This would break terribly as 1150 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1151 * historical behavior where the underlying file could 1152 * not be sealed. 1153 */ 1154 initial_seals &= ~shmfd->shm_seals; 1155 1156 /* 1157 * Object already exists, obtain a new 1158 * reference if requested and permitted. 1159 */ 1160 free(path, M_SHMFD); 1161 1162 /* 1163 * initial_seals can't set additional seals if we've 1164 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1165 * then we've already removed that one from 1166 * initial_seals. This is currently redundant as we 1167 * only allow setting F_SEAL_SEAL at creation time, but 1168 * it's cheap to check and decreases the effort required 1169 * to allow additional seals. 1170 */ 1171 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1172 initial_seals != 0) 1173 error = EPERM; 1174 else if ((flags & (O_CREAT | O_EXCL)) == 1175 (O_CREAT | O_EXCL)) 1176 error = EEXIST; 1177 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1178 error = EINVAL; 1179 else { 1180 #ifdef MAC 1181 error = mac_posixshm_check_open(td->td_ucred, 1182 shmfd, FFLAGS(flags & O_ACCMODE)); 1183 if (error == 0) 1184 #endif 1185 error = shm_access(shmfd, td->td_ucred, 1186 FFLAGS(flags & O_ACCMODE)); 1187 } 1188 1189 /* 1190 * Truncate the file back to zero length if 1191 * O_TRUNC was specified and the object was 1192 * opened with read/write. 1193 */ 1194 if (error == 0 && 1195 (flags & (O_ACCMODE | O_TRUNC)) == 1196 (O_RDWR | O_TRUNC)) { 1197 VM_OBJECT_WLOCK(shmfd->shm_object); 1198 #ifdef MAC 1199 error = mac_posixshm_check_truncate( 1200 td->td_ucred, fp->f_cred, shmfd); 1201 if (error == 0) 1202 #endif 1203 error = shm_dotruncate_locked(shmfd, 0, 1204 rl_cookie); 1205 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1206 } 1207 if (error == 0) { 1208 /* 1209 * Currently we only allow F_SEAL_SEAL to be 1210 * set initially. As noted above, this would 1211 * need to be reworked should that change. 1212 */ 1213 shmfd->shm_seals |= initial_seals; 1214 shm_hold(shmfd); 1215 } 1216 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 1217 &shmfd->shm_mtx); 1218 } 1219 sx_xunlock(&shm_dict_lock); 1220 1221 if (error) { 1222 fdclose(td, fp, fd); 1223 fdrop(fp, td); 1224 return (error); 1225 } 1226 } 1227 1228 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1229 1230 td->td_retval[0] = fd; 1231 fdrop(fp, td); 1232 1233 return (0); 1234 } 1235 1236 /* System calls. */ 1237 #ifdef COMPAT_FREEBSD12 1238 int 1239 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1240 { 1241 1242 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1243 uap->mode, NULL)); 1244 } 1245 #endif 1246 1247 int 1248 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1249 { 1250 char *path; 1251 Fnv32_t fnv; 1252 int error; 1253 1254 error = shm_copyin_path(td, uap->path, &path); 1255 if (error != 0) 1256 return (error); 1257 1258 AUDIT_ARG_UPATH1_CANON(path); 1259 fnv = fnv_32_str(path, FNV1_32_INIT); 1260 sx_xlock(&shm_dict_lock); 1261 error = shm_remove(path, fnv, td->td_ucred); 1262 sx_xunlock(&shm_dict_lock); 1263 free(path, M_SHMFD); 1264 1265 return (error); 1266 } 1267 1268 int 1269 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1270 { 1271 char *path_from = NULL, *path_to = NULL; 1272 Fnv32_t fnv_from, fnv_to; 1273 struct shmfd *fd_from; 1274 struct shmfd *fd_to; 1275 int error; 1276 int flags; 1277 1278 flags = uap->flags; 1279 AUDIT_ARG_FFLAGS(flags); 1280 1281 /* 1282 * Make sure the user passed only valid flags. 1283 * If you add a new flag, please add a new term here. 1284 */ 1285 if ((flags & ~( 1286 SHM_RENAME_NOREPLACE | 1287 SHM_RENAME_EXCHANGE 1288 )) != 0) { 1289 error = EINVAL; 1290 goto out; 1291 } 1292 1293 /* 1294 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1295 * force the user to choose one or the other. 1296 */ 1297 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1298 (flags & SHM_RENAME_EXCHANGE) != 0) { 1299 error = EINVAL; 1300 goto out; 1301 } 1302 1303 /* Renaming to or from anonymous makes no sense */ 1304 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1305 error = EINVAL; 1306 goto out; 1307 } 1308 1309 error = shm_copyin_path(td, uap->path_from, &path_from); 1310 if (error != 0) 1311 goto out; 1312 1313 error = shm_copyin_path(td, uap->path_to, &path_to); 1314 if (error != 0) 1315 goto out; 1316 1317 AUDIT_ARG_UPATH1_CANON(path_from); 1318 AUDIT_ARG_UPATH2_CANON(path_to); 1319 1320 /* Rename with from/to equal is a no-op */ 1321 if (strcmp(path_from, path_to) == 0) 1322 goto out; 1323 1324 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1325 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1326 1327 sx_xlock(&shm_dict_lock); 1328 1329 fd_from = shm_lookup(path_from, fnv_from); 1330 if (fd_from == NULL) { 1331 error = ENOENT; 1332 goto out_locked; 1333 } 1334 1335 fd_to = shm_lookup(path_to, fnv_to); 1336 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1337 error = EEXIST; 1338 goto out_locked; 1339 } 1340 1341 /* 1342 * Unconditionally prevents shm_remove from invalidating the 'from' 1343 * shm's state. 1344 */ 1345 shm_hold(fd_from); 1346 error = shm_remove(path_from, fnv_from, td->td_ucred); 1347 1348 /* 1349 * One of my assumptions failed if ENOENT (e.g. locking didn't 1350 * protect us) 1351 */ 1352 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1353 path_from)); 1354 if (error != 0) { 1355 shm_drop(fd_from); 1356 goto out_locked; 1357 } 1358 1359 /* 1360 * If we are exchanging, we need to ensure the shm_remove below 1361 * doesn't invalidate the dest shm's state. 1362 */ 1363 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1364 shm_hold(fd_to); 1365 1366 /* 1367 * NOTE: if path_to is not already in the hash, c'est la vie; 1368 * it simply means we have nothing already at path_to to unlink. 1369 * That is the ENOENT case. 1370 * 1371 * If we somehow don't have access to unlink this guy, but 1372 * did for the shm at path_from, then relink the shm to path_from 1373 * and abort with EACCES. 1374 * 1375 * All other errors: that is weird; let's relink and abort the 1376 * operation. 1377 */ 1378 error = shm_remove(path_to, fnv_to, td->td_ucred); 1379 if (error != 0 && error != ENOENT) { 1380 shm_insert(path_from, fnv_from, fd_from); 1381 shm_drop(fd_from); 1382 /* Don't free path_from now, since the hash references it */ 1383 path_from = NULL; 1384 goto out_locked; 1385 } 1386 1387 error = 0; 1388 1389 shm_insert(path_to, fnv_to, fd_from); 1390 1391 /* Don't free path_to now, since the hash references it */ 1392 path_to = NULL; 1393 1394 /* We kept a ref when we removed, and incremented again in insert */ 1395 shm_drop(fd_from); 1396 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1397 fd_from->shm_refs)); 1398 1399 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1400 shm_insert(path_from, fnv_from, fd_to); 1401 path_from = NULL; 1402 shm_drop(fd_to); 1403 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1404 fd_to->shm_refs)); 1405 } 1406 1407 out_locked: 1408 sx_xunlock(&shm_dict_lock); 1409 1410 out: 1411 free(path_from, M_SHMFD); 1412 free(path_to, M_SHMFD); 1413 return (error); 1414 } 1415 1416 static int 1417 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1418 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1419 vm_ooffset_t foff, struct thread *td) 1420 { 1421 struct vmspace *vms; 1422 vm_map_entry_t next_entry, prev_entry; 1423 vm_offset_t align, mask, maxaddr; 1424 int docow, error, rv, try; 1425 bool curmap; 1426 1427 if (shmfd->shm_lp_psind == 0) 1428 return (EINVAL); 1429 1430 /* MAP_PRIVATE is disabled */ 1431 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1432 MAP_NOCORE | 1433 #ifdef MAP_32BIT 1434 MAP_32BIT | 1435 #endif 1436 MAP_ALIGNMENT_MASK)) != 0) 1437 return (EINVAL); 1438 1439 vms = td->td_proc->p_vmspace; 1440 curmap = map == &vms->vm_map; 1441 if (curmap) { 1442 error = kern_mmap_racct_check(td, map, size); 1443 if (error != 0) 1444 return (error); 1445 } 1446 1447 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1448 docow |= MAP_INHERIT_SHARE; 1449 if ((flags & MAP_NOCORE) != 0) 1450 docow |= MAP_DISABLE_COREDUMP; 1451 1452 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1453 if ((foff & mask) != 0) 1454 return (EINVAL); 1455 maxaddr = vm_map_max(map); 1456 #ifdef MAP_32BIT 1457 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1458 maxaddr = MAP_32BIT_MAX_ADDR; 1459 #endif 1460 if (size == 0 || (size & mask) != 0 || 1461 (*addr != 0 && ((*addr & mask) != 0 || 1462 *addr + size < *addr || *addr + size > maxaddr))) 1463 return (EINVAL); 1464 1465 align = flags & MAP_ALIGNMENT_MASK; 1466 if (align == 0) { 1467 align = pagesizes[shmfd->shm_lp_psind]; 1468 } else if (align == MAP_ALIGNED_SUPER) { 1469 if (shmfd->shm_lp_psind != 1) 1470 return (EINVAL); 1471 align = pagesizes[1]; 1472 } else { 1473 align >>= MAP_ALIGNMENT_SHIFT; 1474 align = 1ULL << align; 1475 /* Also handles overflow. */ 1476 if (align < pagesizes[shmfd->shm_lp_psind]) 1477 return (EINVAL); 1478 } 1479 1480 vm_map_lock(map); 1481 if ((flags & MAP_FIXED) == 0) { 1482 try = 1; 1483 if (curmap && (*addr == 0 || 1484 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1485 *addr < round_page((vm_offset_t)vms->vm_daddr + 1486 lim_max(td, RLIMIT_DATA))))) { 1487 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1488 lim_max(td, RLIMIT_DATA), 1489 pagesizes[shmfd->shm_lp_psind]); 1490 } 1491 again: 1492 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1493 if (rv != KERN_SUCCESS) { 1494 if (try == 1) { 1495 try = 2; 1496 *addr = vm_map_min(map); 1497 if ((*addr & mask) != 0) 1498 *addr = (*addr + mask) & mask; 1499 goto again; 1500 } 1501 goto fail1; 1502 } 1503 } else if ((flags & MAP_EXCL) == 0) { 1504 rv = vm_map_delete(map, *addr, *addr + size); 1505 if (rv != KERN_SUCCESS) 1506 goto fail1; 1507 } else { 1508 error = ENOSPC; 1509 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1510 goto fail; 1511 next_entry = vm_map_entry_succ(prev_entry); 1512 if (next_entry->start < *addr + size) 1513 goto fail; 1514 } 1515 1516 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1517 prot, max_prot, docow); 1518 fail1: 1519 error = vm_mmap_to_errno(rv); 1520 fail: 1521 vm_map_unlock(map); 1522 return (error); 1523 } 1524 1525 static int 1526 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1527 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1528 vm_ooffset_t foff, struct thread *td) 1529 { 1530 struct shmfd *shmfd; 1531 vm_prot_t maxprot; 1532 int error; 1533 bool writecnt; 1534 void *rl_cookie; 1535 1536 shmfd = fp->f_data; 1537 maxprot = VM_PROT_NONE; 1538 1539 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1540 &shmfd->shm_mtx); 1541 /* FREAD should always be set. */ 1542 if ((fp->f_flag & FREAD) != 0) 1543 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1544 1545 /* 1546 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1547 * mapping with a write seal applied. Private mappings are always 1548 * writeable. 1549 */ 1550 if ((flags & MAP_SHARED) == 0) { 1551 cap_maxprot |= VM_PROT_WRITE; 1552 maxprot |= VM_PROT_WRITE; 1553 writecnt = false; 1554 } else { 1555 if ((fp->f_flag & FWRITE) != 0 && 1556 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1557 maxprot |= VM_PROT_WRITE; 1558 1559 /* 1560 * Any mappings from a writable descriptor may be upgraded to 1561 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1562 * applied between the open and subsequent mmap(2). We want to 1563 * reject application of a write seal as long as any such 1564 * mapping exists so that the seal cannot be trivially bypassed. 1565 */ 1566 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1567 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1568 error = EACCES; 1569 goto out; 1570 } 1571 } 1572 maxprot &= cap_maxprot; 1573 1574 /* See comment in vn_mmap(). */ 1575 if ( 1576 #ifdef _LP64 1577 objsize > OFF_MAX || 1578 #endif 1579 foff > OFF_MAX - objsize) { 1580 error = EINVAL; 1581 goto out; 1582 } 1583 1584 #ifdef MAC 1585 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1586 if (error != 0) 1587 goto out; 1588 #endif 1589 1590 mtx_lock(&shm_timestamp_lock); 1591 vfs_timestamp(&shmfd->shm_atime); 1592 mtx_unlock(&shm_timestamp_lock); 1593 vm_object_reference(shmfd->shm_object); 1594 1595 if (shm_largepage(shmfd)) { 1596 writecnt = false; 1597 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1598 maxprot, flags, foff, td); 1599 } else { 1600 if (writecnt) { 1601 vm_pager_update_writecount(shmfd->shm_object, 0, 1602 objsize); 1603 } 1604 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1605 shmfd->shm_object, foff, writecnt, td); 1606 } 1607 if (error != 0) { 1608 if (writecnt) 1609 vm_pager_release_writecount(shmfd->shm_object, 0, 1610 objsize); 1611 vm_object_deallocate(shmfd->shm_object); 1612 } 1613 out: 1614 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1615 return (error); 1616 } 1617 1618 static int 1619 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1620 struct thread *td) 1621 { 1622 struct shmfd *shmfd; 1623 int error; 1624 1625 error = 0; 1626 shmfd = fp->f_data; 1627 mtx_lock(&shm_timestamp_lock); 1628 /* 1629 * SUSv4 says that x bits of permission need not be affected. 1630 * Be consistent with our shm_open there. 1631 */ 1632 #ifdef MAC 1633 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1634 if (error != 0) 1635 goto out; 1636 #endif 1637 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1638 VADMIN, active_cred); 1639 if (error != 0) 1640 goto out; 1641 shmfd->shm_mode = mode & ACCESSPERMS; 1642 out: 1643 mtx_unlock(&shm_timestamp_lock); 1644 return (error); 1645 } 1646 1647 static int 1648 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1649 struct thread *td) 1650 { 1651 struct shmfd *shmfd; 1652 int error; 1653 1654 error = 0; 1655 shmfd = fp->f_data; 1656 mtx_lock(&shm_timestamp_lock); 1657 #ifdef MAC 1658 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1659 if (error != 0) 1660 goto out; 1661 #endif 1662 if (uid == (uid_t)-1) 1663 uid = shmfd->shm_uid; 1664 if (gid == (gid_t)-1) 1665 gid = shmfd->shm_gid; 1666 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1667 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1668 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1669 goto out; 1670 shmfd->shm_uid = uid; 1671 shmfd->shm_gid = gid; 1672 out: 1673 mtx_unlock(&shm_timestamp_lock); 1674 return (error); 1675 } 1676 1677 /* 1678 * Helper routines to allow the backing object of a shared memory file 1679 * descriptor to be mapped in the kernel. 1680 */ 1681 int 1682 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1683 { 1684 struct shmfd *shmfd; 1685 vm_offset_t kva, ofs; 1686 vm_object_t obj; 1687 int rv; 1688 1689 if (fp->f_type != DTYPE_SHM) 1690 return (EINVAL); 1691 shmfd = fp->f_data; 1692 obj = shmfd->shm_object; 1693 VM_OBJECT_WLOCK(obj); 1694 /* 1695 * XXXRW: This validation is probably insufficient, and subject to 1696 * sign errors. It should be fixed. 1697 */ 1698 if (offset >= shmfd->shm_size || 1699 offset + size > round_page(shmfd->shm_size)) { 1700 VM_OBJECT_WUNLOCK(obj); 1701 return (EINVAL); 1702 } 1703 1704 shmfd->shm_kmappings++; 1705 vm_object_reference_locked(obj); 1706 VM_OBJECT_WUNLOCK(obj); 1707 1708 /* Map the object into the kernel_map and wire it. */ 1709 kva = vm_map_min(kernel_map); 1710 ofs = offset & PAGE_MASK; 1711 offset = trunc_page(offset); 1712 size = round_page(size + ofs); 1713 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1714 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1715 VM_PROT_READ | VM_PROT_WRITE, 0); 1716 if (rv == KERN_SUCCESS) { 1717 rv = vm_map_wire(kernel_map, kva, kva + size, 1718 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1719 if (rv == KERN_SUCCESS) { 1720 *memp = (void *)(kva + ofs); 1721 return (0); 1722 } 1723 vm_map_remove(kernel_map, kva, kva + size); 1724 } else 1725 vm_object_deallocate(obj); 1726 1727 /* On failure, drop our mapping reference. */ 1728 VM_OBJECT_WLOCK(obj); 1729 shmfd->shm_kmappings--; 1730 VM_OBJECT_WUNLOCK(obj); 1731 1732 return (vm_mmap_to_errno(rv)); 1733 } 1734 1735 /* 1736 * We require the caller to unmap the entire entry. This allows us to 1737 * safely decrement shm_kmappings when a mapping is removed. 1738 */ 1739 int 1740 shm_unmap(struct file *fp, void *mem, size_t size) 1741 { 1742 struct shmfd *shmfd; 1743 vm_map_entry_t entry; 1744 vm_offset_t kva, ofs; 1745 vm_object_t obj; 1746 vm_pindex_t pindex; 1747 vm_prot_t prot; 1748 boolean_t wired; 1749 vm_map_t map; 1750 int rv; 1751 1752 if (fp->f_type != DTYPE_SHM) 1753 return (EINVAL); 1754 shmfd = fp->f_data; 1755 kva = (vm_offset_t)mem; 1756 ofs = kva & PAGE_MASK; 1757 kva = trunc_page(kva); 1758 size = round_page(size + ofs); 1759 map = kernel_map; 1760 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1761 &obj, &pindex, &prot, &wired); 1762 if (rv != KERN_SUCCESS) 1763 return (EINVAL); 1764 if (entry->start != kva || entry->end != kva + size) { 1765 vm_map_lookup_done(map, entry); 1766 return (EINVAL); 1767 } 1768 vm_map_lookup_done(map, entry); 1769 if (obj != shmfd->shm_object) 1770 return (EINVAL); 1771 vm_map_remove(map, kva, kva + size); 1772 VM_OBJECT_WLOCK(obj); 1773 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1774 shmfd->shm_kmappings--; 1775 VM_OBJECT_WUNLOCK(obj); 1776 return (0); 1777 } 1778 1779 static int 1780 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1781 { 1782 const char *path, *pr_path; 1783 size_t pr_pathlen; 1784 bool visible; 1785 1786 sx_assert(&shm_dict_lock, SA_LOCKED); 1787 kif->kf_type = KF_TYPE_SHM; 1788 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1789 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1790 if (shmfd->shm_path != NULL) { 1791 if (shmfd->shm_path != NULL) { 1792 path = shmfd->shm_path; 1793 pr_path = curthread->td_ucred->cr_prison->pr_path; 1794 if (strcmp(pr_path, "/") != 0) { 1795 /* Return the jail-rooted pathname. */ 1796 pr_pathlen = strlen(pr_path); 1797 visible = strncmp(path, pr_path, pr_pathlen) 1798 == 0 && path[pr_pathlen] == '/'; 1799 if (list && !visible) 1800 return (EPERM); 1801 if (visible) 1802 path += pr_pathlen; 1803 } 1804 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1805 } 1806 } 1807 return (0); 1808 } 1809 1810 static int 1811 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1812 struct filedesc *fdp __unused) 1813 { 1814 int res; 1815 1816 sx_slock(&shm_dict_lock); 1817 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1818 sx_sunlock(&shm_dict_lock); 1819 return (res); 1820 } 1821 1822 static int 1823 shm_add_seals(struct file *fp, int seals) 1824 { 1825 struct shmfd *shmfd; 1826 void *rl_cookie; 1827 vm_ooffset_t writemappings; 1828 int error, nseals; 1829 1830 error = 0; 1831 shmfd = fp->f_data; 1832 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1833 &shmfd->shm_mtx); 1834 1835 /* Even already-set seals should result in EPERM. */ 1836 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1837 error = EPERM; 1838 goto out; 1839 } 1840 nseals = seals & ~shmfd->shm_seals; 1841 if ((nseals & F_SEAL_WRITE) != 0) { 1842 if (shm_largepage(shmfd)) { 1843 error = ENOTSUP; 1844 goto out; 1845 } 1846 1847 /* 1848 * The rangelock above prevents writable mappings from being 1849 * added after we've started applying seals. The RLOCK here 1850 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1851 * writemappings will be done without a rangelock. 1852 */ 1853 VM_OBJECT_RLOCK(shmfd->shm_object); 1854 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1855 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1856 /* kmappings are also writable */ 1857 if (writemappings > 0) { 1858 error = EBUSY; 1859 goto out; 1860 } 1861 } 1862 shmfd->shm_seals |= nseals; 1863 out: 1864 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1865 return (error); 1866 } 1867 1868 static int 1869 shm_get_seals(struct file *fp, int *seals) 1870 { 1871 struct shmfd *shmfd; 1872 1873 shmfd = fp->f_data; 1874 *seals = shmfd->shm_seals; 1875 return (0); 1876 } 1877 1878 static int 1879 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 1880 { 1881 void *rl_cookie; 1882 struct shmfd *shmfd; 1883 size_t size; 1884 int error; 1885 1886 /* This assumes that the caller already checked for overflow. */ 1887 error = 0; 1888 shmfd = fp->f_data; 1889 size = offset + len; 1890 1891 /* 1892 * Just grab the rangelock for the range that we may be attempting to 1893 * grow, rather than blocking read/write for regions we won't be 1894 * touching while this (potential) resize is in progress. Other 1895 * attempts to resize the shmfd will have to take a write lock from 0 to 1896 * OFF_MAX, so this being potentially beyond the current usable range of 1897 * the shmfd is not necessarily a concern. If other mechanisms are 1898 * added to grow a shmfd, this may need to be re-evaluated. 1899 */ 1900 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 1901 &shmfd->shm_mtx); 1902 if (size > shmfd->shm_size) 1903 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 1904 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1905 /* Translate to posix_fallocate(2) return value as needed. */ 1906 if (error == ENOMEM) 1907 error = ENOSPC; 1908 return (error); 1909 } 1910 1911 static int 1912 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1913 { 1914 struct shm_mapping *shmm; 1915 struct sbuf sb; 1916 struct kinfo_file kif; 1917 u_long i; 1918 ssize_t curlen; 1919 int error, error2; 1920 1921 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1922 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1923 curlen = 0; 1924 error = 0; 1925 sx_slock(&shm_dict_lock); 1926 for (i = 0; i < shm_hash + 1; i++) { 1927 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1928 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1929 &kif, true); 1930 if (error == EPERM) { 1931 error = 0; 1932 continue; 1933 } 1934 if (error != 0) 1935 break; 1936 pack_kinfo(&kif); 1937 if (req->oldptr != NULL && 1938 kif.kf_structsize + curlen > req->oldlen) 1939 break; 1940 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1941 0 : ENOMEM; 1942 if (error != 0) 1943 break; 1944 curlen += kif.kf_structsize; 1945 } 1946 } 1947 sx_sunlock(&shm_dict_lock); 1948 error2 = sbuf_finish(&sb); 1949 sbuf_delete(&sb); 1950 return (error != 0 ? error : error2); 1951 } 1952 1953 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1954 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1955 NULL, 0, sysctl_posix_shm_list, "", 1956 "POSIX SHM list"); 1957 1958 int 1959 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1960 struct filecaps *caps) 1961 { 1962 1963 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1964 } 1965 1966 /* 1967 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1968 * caller, and libc will enforce it for the traditional shm_open() call. This 1969 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1970 * interface also includes a 'name' argument that is currently unused, but could 1971 * potentially be exported later via some interface for debugging purposes. 1972 * From the kernel's perspective, it is optional. Individual consumers like 1973 * memfd_create() may require it in order to be compatible with other systems 1974 * implementing the same function. 1975 */ 1976 int 1977 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1978 { 1979 1980 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1981 uap->shmflags, NULL, uap->name)); 1982 }
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