Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
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 void shm_doremove(struct shm_mapping *map); 129 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 130 void *rl_cookie); 131 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 132 void *rl_cookie); 133 static int shm_copyin_path(struct thread *td, const char *userpath_in, 134 char **path_out); 135 static int shm_deallocate(struct shmfd *shmfd, off_t *offset, 136 off_t *length, int flags); 137 138 static fo_rdwr_t shm_read; 139 static fo_rdwr_t shm_write; 140 static fo_truncate_t shm_truncate; 141 static fo_ioctl_t shm_ioctl; 142 static fo_stat_t shm_stat; 143 static fo_close_t shm_close; 144 static fo_chmod_t shm_chmod; 145 static fo_chown_t shm_chown; 146 static fo_seek_t shm_seek; 147 static fo_fill_kinfo_t shm_fill_kinfo; 148 static fo_mmap_t shm_mmap; 149 static fo_get_seals_t shm_get_seals; 150 static fo_add_seals_t shm_add_seals; 151 static fo_fallocate_t shm_fallocate; 152 static fo_fspacectl_t shm_fspacectl; 153 154 /* File descriptor operations. */ 155 struct fileops shm_ops = { 156 .fo_read = shm_read, 157 .fo_write = shm_write, 158 .fo_truncate = shm_truncate, 159 .fo_ioctl = shm_ioctl, 160 .fo_poll = invfo_poll, 161 .fo_kqfilter = invfo_kqfilter, 162 .fo_stat = shm_stat, 163 .fo_close = shm_close, 164 .fo_chmod = shm_chmod, 165 .fo_chown = shm_chown, 166 .fo_sendfile = vn_sendfile, 167 .fo_seek = shm_seek, 168 .fo_fill_kinfo = shm_fill_kinfo, 169 .fo_mmap = shm_mmap, 170 .fo_get_seals = shm_get_seals, 171 .fo_add_seals = shm_add_seals, 172 .fo_fallocate = shm_fallocate, 173 .fo_fspacectl = shm_fspacectl, 174 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 175 }; 176 177 FEATURE(posix_shm, "POSIX shared memory"); 178 179 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 180 ""); 181 182 static int largepage_reclaim_tries = 1; 183 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 184 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 185 "Number of contig reclaims before giving up for default alloc policy"); 186 187 static int 188 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 189 { 190 vm_page_t m; 191 vm_pindex_t idx; 192 size_t tlen; 193 int error, offset, rv; 194 195 idx = OFF_TO_IDX(uio->uio_offset); 196 offset = uio->uio_offset & PAGE_MASK; 197 tlen = MIN(PAGE_SIZE - offset, len); 198 199 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 200 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 201 if (rv == VM_PAGER_OK) 202 goto found; 203 204 /* 205 * Read I/O without either a corresponding resident page or swap 206 * page: use zero_region. This is intended to avoid instantiating 207 * pages on read from a sparse region. 208 */ 209 VM_OBJECT_WLOCK(obj); 210 m = vm_page_lookup(obj, idx); 211 if (uio->uio_rw == UIO_READ && m == NULL && 212 !vm_pager_has_page(obj, idx, NULL, NULL)) { 213 VM_OBJECT_WUNLOCK(obj); 214 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 215 } 216 217 /* 218 * Although the tmpfs vnode lock is held here, it is 219 * nonetheless safe to sleep waiting for a free page. The 220 * pageout daemon does not need to acquire the tmpfs vnode 221 * lock to page out tobj's pages because tobj is a OBJT_SWAP 222 * type object. 223 */ 224 rv = vm_page_grab_valid(&m, obj, idx, 225 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 226 if (rv != VM_PAGER_OK) { 227 VM_OBJECT_WUNLOCK(obj); 228 if (bootverbose) { 229 printf("uiomove_object: vm_obj %p idx %jd " 230 "pager error %d\n", obj, idx, rv); 231 } 232 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO); 233 } 234 VM_OBJECT_WUNLOCK(obj); 235 236 found: 237 error = uiomove_fromphys(&m, offset, tlen, uio); 238 if (uio->uio_rw == UIO_WRITE && error == 0) 239 vm_page_set_dirty(m); 240 vm_page_activate(m); 241 vm_page_sunbusy(m); 242 243 return (error); 244 } 245 246 int 247 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 248 { 249 ssize_t resid; 250 size_t len; 251 int error; 252 253 error = 0; 254 while ((resid = uio->uio_resid) > 0) { 255 if (obj_size <= uio->uio_offset) 256 break; 257 len = MIN(obj_size - uio->uio_offset, resid); 258 if (len == 0) 259 break; 260 error = uiomove_object_page(obj, len, uio); 261 if (error != 0 || resid == uio->uio_resid) 262 break; 263 } 264 return (error); 265 } 266 267 static u_long count_largepages[MAXPAGESIZES]; 268 269 static int 270 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 271 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 272 { 273 vm_page_t m __diagused; 274 int psind; 275 276 psind = object->un_pager.phys.data_val; 277 if (psind == 0 || pidx >= object->size) 278 return (VM_PAGER_FAIL); 279 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 280 281 /* 282 * We only busy the first page in the superpage run. It is 283 * useless to busy whole run since we only remove full 284 * superpage, and it takes too long to busy e.g. 512 * 512 == 285 * 262144 pages constituing 1G amd64 superage. 286 */ 287 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 288 MPASS(m != NULL); 289 290 *last = *first + atop(pagesizes[psind]) - 1; 291 return (VM_PAGER_OK); 292 } 293 294 static boolean_t 295 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 296 int *before, int *after) 297 { 298 int psind; 299 300 psind = object->un_pager.phys.data_val; 301 if (psind == 0 || pindex >= object->size) 302 return (FALSE); 303 if (before != NULL) { 304 *before = pindex - rounddown2(pindex, pagesizes[psind] / 305 PAGE_SIZE); 306 } 307 if (after != NULL) { 308 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 309 pindex; 310 } 311 return (TRUE); 312 } 313 314 static void 315 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 316 vm_ooffset_t foff, struct ucred *cred) 317 { 318 } 319 320 static void 321 shm_largepage_phys_dtor(vm_object_t object) 322 { 323 int psind; 324 325 psind = object->un_pager.phys.data_val; 326 if (psind != 0) { 327 atomic_subtract_long(&count_largepages[psind], 328 object->size / (pagesizes[psind] / PAGE_SIZE)); 329 vm_wire_sub(object->size); 330 } else { 331 KASSERT(object->size == 0, 332 ("largepage phys obj %p not initialized bit size %#jx > 0", 333 object, (uintmax_t)object->size)); 334 } 335 } 336 337 static const struct phys_pager_ops shm_largepage_phys_ops = { 338 .phys_pg_populate = shm_largepage_phys_populate, 339 .phys_pg_haspage = shm_largepage_phys_haspage, 340 .phys_pg_ctor = shm_largepage_phys_ctor, 341 .phys_pg_dtor = shm_largepage_phys_dtor, 342 }; 343 344 bool 345 shm_largepage(struct shmfd *shmfd) 346 { 347 return (shmfd->shm_object->type == OBJT_PHYS); 348 } 349 350 static void 351 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size) 352 { 353 struct shmfd *shm; 354 vm_size_t c; 355 356 swap_pager_freespace(obj, start, size, &c); 357 if (c == 0) 358 return; 359 360 shm = obj->un_pager.swp.swp_priv; 361 if (shm == NULL) 362 return; 363 KASSERT(shm->shm_pages >= c, 364 ("shm %p pages %jd free %jd", shm, 365 (uintmax_t)shm->shm_pages, (uintmax_t)c)); 366 shm->shm_pages -= c; 367 } 368 369 static void 370 shm_page_inserted(vm_object_t obj, vm_page_t m) 371 { 372 struct shmfd *shm; 373 374 shm = obj->un_pager.swp.swp_priv; 375 if (shm == NULL) 376 return; 377 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) 378 shm->shm_pages += 1; 379 } 380 381 static void 382 shm_page_removed(vm_object_t obj, vm_page_t m) 383 { 384 struct shmfd *shm; 385 386 shm = obj->un_pager.swp.swp_priv; 387 if (shm == NULL) 388 return; 389 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) { 390 KASSERT(shm->shm_pages >= 1, 391 ("shm %p pages %jd free 1", shm, 392 (uintmax_t)shm->shm_pages)); 393 shm->shm_pages -= 1; 394 } 395 } 396 397 static struct pagerops shm_swap_pager_ops = { 398 .pgo_kvme_type = KVME_TYPE_SWAP, 399 .pgo_freespace = shm_pager_freespace, 400 .pgo_page_inserted = shm_page_inserted, 401 .pgo_page_removed = shm_page_removed, 402 }; 403 static int shmfd_pager_type = -1; 404 405 static int 406 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 407 { 408 struct shmfd *shmfd; 409 off_t foffset; 410 int error; 411 412 shmfd = fp->f_data; 413 foffset = foffset_lock(fp, 0); 414 error = 0; 415 switch (whence) { 416 case L_INCR: 417 if (foffset < 0 || 418 (offset > 0 && foffset > OFF_MAX - offset)) { 419 error = EOVERFLOW; 420 break; 421 } 422 offset += foffset; 423 break; 424 case L_XTND: 425 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 426 error = EOVERFLOW; 427 break; 428 } 429 offset += shmfd->shm_size; 430 break; 431 case L_SET: 432 break; 433 default: 434 error = EINVAL; 435 } 436 if (error == 0) { 437 if (offset < 0 || offset > shmfd->shm_size) 438 error = EINVAL; 439 else 440 td->td_uretoff.tdu_off = offset; 441 } 442 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 443 return (error); 444 } 445 446 static int 447 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 448 int flags, struct thread *td) 449 { 450 struct shmfd *shmfd; 451 void *rl_cookie; 452 int error; 453 454 shmfd = fp->f_data; 455 #ifdef MAC 456 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 457 if (error) 458 return (error); 459 #endif 460 foffset_lock_uio(fp, uio, flags); 461 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 462 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 463 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 464 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 465 foffset_unlock_uio(fp, uio, flags); 466 return (error); 467 } 468 469 static int 470 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 471 int flags, struct thread *td) 472 { 473 struct shmfd *shmfd; 474 void *rl_cookie; 475 int error; 476 off_t size; 477 478 shmfd = fp->f_data; 479 #ifdef MAC 480 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 481 if (error) 482 return (error); 483 #endif 484 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 485 return (EINVAL); 486 foffset_lock_uio(fp, uio, flags); 487 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 488 /* 489 * Overflow is only an error if we're supposed to expand on 490 * write. Otherwise, we'll just truncate the write to the 491 * size of the file, which can only grow up to OFF_MAX. 492 */ 493 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 494 foffset_unlock_uio(fp, uio, flags); 495 return (EFBIG); 496 } 497 498 size = shmfd->shm_size; 499 } else { 500 size = uio->uio_offset + uio->uio_resid; 501 } 502 if ((flags & FOF_OFFSET) == 0) { 503 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 504 &shmfd->shm_mtx); 505 } else { 506 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 507 size, &shmfd->shm_mtx); 508 } 509 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 510 error = EPERM; 511 } else { 512 error = 0; 513 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 514 size > shmfd->shm_size) { 515 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 516 } 517 if (error == 0) 518 error = uiomove_object(shmfd->shm_object, 519 shmfd->shm_size, uio); 520 } 521 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 522 foffset_unlock_uio(fp, uio, flags); 523 return (error); 524 } 525 526 static int 527 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 528 struct thread *td) 529 { 530 struct shmfd *shmfd; 531 #ifdef MAC 532 int error; 533 #endif 534 535 shmfd = fp->f_data; 536 #ifdef MAC 537 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 538 if (error) 539 return (error); 540 #endif 541 return (shm_dotruncate(shmfd, length)); 542 } 543 544 int 545 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 546 struct thread *td) 547 { 548 struct shmfd *shmfd; 549 struct shm_largepage_conf *conf; 550 void *rl_cookie; 551 552 shmfd = fp->f_data; 553 switch (com) { 554 case FIONBIO: 555 case FIOASYNC: 556 /* 557 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 558 * just like it would on an unlinked regular file 559 */ 560 return (0); 561 case FIOSSHMLPGCNF: 562 if (!shm_largepage(shmfd)) 563 return (ENOTTY); 564 conf = data; 565 if (shmfd->shm_lp_psind != 0 && 566 conf->psind != shmfd->shm_lp_psind) 567 return (EINVAL); 568 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 569 pagesizes[conf->psind] == 0) 570 return (EINVAL); 571 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 572 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 573 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 574 return (EINVAL); 575 576 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 577 &shmfd->shm_mtx); 578 shmfd->shm_lp_psind = conf->psind; 579 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 580 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 581 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 582 return (0); 583 case FIOGSHMLPGCNF: 584 if (!shm_largepage(shmfd)) 585 return (ENOTTY); 586 conf = data; 587 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX, 588 &shmfd->shm_mtx); 589 conf->psind = shmfd->shm_lp_psind; 590 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 591 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 592 return (0); 593 default: 594 return (ENOTTY); 595 } 596 } 597 598 static int 599 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred) 600 { 601 struct shmfd *shmfd; 602 #ifdef MAC 603 int error; 604 #endif 605 606 shmfd = fp->f_data; 607 608 #ifdef MAC 609 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 610 if (error) 611 return (error); 612 #endif 613 614 /* 615 * Attempt to return sanish values for fstat() on a memory file 616 * descriptor. 617 */ 618 bzero(sb, sizeof(*sb)); 619 sb->st_blksize = PAGE_SIZE; 620 sb->st_size = shmfd->shm_size; 621 mtx_lock(&shm_timestamp_lock); 622 sb->st_atim = shmfd->shm_atime; 623 sb->st_ctim = shmfd->shm_ctime; 624 sb->st_mtim = shmfd->shm_mtime; 625 sb->st_birthtim = shmfd->shm_birthtime; 626 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 627 sb->st_uid = shmfd->shm_uid; 628 sb->st_gid = shmfd->shm_gid; 629 mtx_unlock(&shm_timestamp_lock); 630 sb->st_dev = shm_dev_ino; 631 sb->st_ino = shmfd->shm_ino; 632 sb->st_nlink = shmfd->shm_object->ref_count; 633 if (shm_largepage(shmfd)) { 634 sb->st_blocks = shmfd->shm_object->size / 635 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 636 } else { 637 sb->st_blocks = shmfd->shm_pages; 638 } 639 640 return (0); 641 } 642 643 static int 644 shm_close(struct file *fp, struct thread *td) 645 { 646 struct shmfd *shmfd; 647 648 shmfd = fp->f_data; 649 fp->f_data = NULL; 650 shm_drop(shmfd); 651 652 return (0); 653 } 654 655 static int 656 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 657 int error; 658 char *path; 659 const char *pr_path; 660 size_t pr_pathlen; 661 662 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 663 pr_path = td->td_ucred->cr_prison->pr_path; 664 665 /* Construct a full pathname for jailed callers. */ 666 pr_pathlen = strcmp(pr_path, "/") == 667 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 668 error = copyinstr(userpath_in, path + pr_pathlen, 669 MAXPATHLEN - pr_pathlen, NULL); 670 if (error != 0) 671 goto out; 672 673 #ifdef KTRACE 674 if (KTRPOINT(curthread, KTR_NAMEI)) 675 ktrnamei(path); 676 #endif 677 678 /* Require paths to start with a '/' character. */ 679 if (path[pr_pathlen] != '/') { 680 error = EINVAL; 681 goto out; 682 } 683 684 *path_out = path; 685 686 out: 687 if (error != 0) 688 free(path, M_SHMFD); 689 690 return (error); 691 } 692 693 static int 694 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base, 695 int end) 696 { 697 vm_page_t m; 698 int rv; 699 700 VM_OBJECT_ASSERT_WLOCKED(object); 701 KASSERT(base >= 0, ("%s: base %d", __func__, base)); 702 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base, 703 end)); 704 705 retry: 706 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 707 if (m != NULL) { 708 MPASS(vm_page_all_valid(m)); 709 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 710 m = vm_page_alloc(object, idx, 711 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 712 if (m == NULL) 713 goto retry; 714 vm_object_pip_add(object, 1); 715 VM_OBJECT_WUNLOCK(object); 716 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL); 717 VM_OBJECT_WLOCK(object); 718 vm_object_pip_wakeup(object); 719 if (rv == VM_PAGER_OK) { 720 /* 721 * Since the page was not resident, and therefore not 722 * recently accessed, immediately enqueue it for 723 * asynchronous laundering. The current operation is 724 * not regarded as an access. 725 */ 726 vm_page_launder(m); 727 } else { 728 vm_page_free(m); 729 VM_OBJECT_WUNLOCK(object); 730 return (EIO); 731 } 732 } 733 if (m != NULL) { 734 pmap_zero_page_area(m, base, end - base); 735 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid", 736 __func__, m)); 737 vm_page_set_dirty(m); 738 vm_page_xunbusy(m); 739 } 740 741 return (0); 742 } 743 744 static int 745 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 746 { 747 vm_object_t object; 748 vm_pindex_t nobjsize; 749 vm_ooffset_t delta; 750 int base, error; 751 752 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 753 object = shmfd->shm_object; 754 VM_OBJECT_ASSERT_WLOCKED(object); 755 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 756 if (length == shmfd->shm_size) 757 return (0); 758 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 759 760 /* Are we shrinking? If so, trim the end. */ 761 if (length < shmfd->shm_size) { 762 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 763 return (EPERM); 764 765 /* 766 * Disallow any requests to shrink the size if this 767 * object is mapped into the kernel. 768 */ 769 if (shmfd->shm_kmappings > 0) 770 return (EBUSY); 771 772 /* 773 * Zero the truncated part of the last page. 774 */ 775 base = length & PAGE_MASK; 776 if (base != 0) { 777 error = shm_partial_page_invalidate(object, 778 OFF_TO_IDX(length), base, PAGE_SIZE); 779 if (error) 780 return (error); 781 } 782 delta = IDX_TO_OFF(object->size - nobjsize); 783 784 if (nobjsize < object->size) 785 vm_object_page_remove(object, nobjsize, object->size, 786 0); 787 788 /* Free the swap accounted for shm */ 789 swap_release_by_cred(delta, object->cred); 790 object->charge -= delta; 791 } else { 792 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 793 return (EPERM); 794 795 /* Try to reserve additional swap space. */ 796 delta = IDX_TO_OFF(nobjsize - object->size); 797 if (!swap_reserve_by_cred(delta, object->cred)) 798 return (ENOMEM); 799 object->charge += delta; 800 } 801 shmfd->shm_size = length; 802 mtx_lock(&shm_timestamp_lock); 803 vfs_timestamp(&shmfd->shm_ctime); 804 shmfd->shm_mtime = shmfd->shm_ctime; 805 mtx_unlock(&shm_timestamp_lock); 806 object->size = nobjsize; 807 return (0); 808 } 809 810 static int 811 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 812 { 813 vm_object_t object; 814 vm_page_t m; 815 vm_pindex_t newobjsz; 816 vm_pindex_t oldobjsz __unused; 817 int aflags, error, i, psind, try; 818 819 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 820 object = shmfd->shm_object; 821 VM_OBJECT_ASSERT_WLOCKED(object); 822 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 823 824 oldobjsz = object->size; 825 newobjsz = OFF_TO_IDX(length); 826 if (length == shmfd->shm_size) 827 return (0); 828 psind = shmfd->shm_lp_psind; 829 if (psind == 0 && length != 0) 830 return (EINVAL); 831 if ((length & (pagesizes[psind] - 1)) != 0) 832 return (EINVAL); 833 834 if (length < shmfd->shm_size) { 835 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 836 return (EPERM); 837 if (shmfd->shm_kmappings > 0) 838 return (EBUSY); 839 return (ENOTSUP); /* Pages are unmanaged. */ 840 #if 0 841 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 842 object->size = newobjsz; 843 shmfd->shm_size = length; 844 return (0); 845 #endif 846 } 847 848 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 849 return (EPERM); 850 851 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 852 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 853 aflags |= VM_ALLOC_WAITFAIL; 854 try = 0; 855 856 /* 857 * Extend shmfd and object, keeping all already fully 858 * allocated large pages intact even on error, because dropped 859 * object lock might allowed mapping of them. 860 */ 861 while (object->size < newobjsz) { 862 m = vm_page_alloc_contig(object, object->size, aflags, 863 pagesizes[psind] / PAGE_SIZE, 0, ~0, 864 pagesizes[psind], 0, 865 VM_MEMATTR_DEFAULT); 866 if (m == NULL) { 867 VM_OBJECT_WUNLOCK(object); 868 if (shmfd->shm_lp_alloc_policy == 869 SHM_LARGEPAGE_ALLOC_NOWAIT || 870 (shmfd->shm_lp_alloc_policy == 871 SHM_LARGEPAGE_ALLOC_DEFAULT && 872 try >= largepage_reclaim_tries)) { 873 VM_OBJECT_WLOCK(object); 874 return (ENOMEM); 875 } 876 error = vm_page_reclaim_contig(aflags, 877 pagesizes[psind] / PAGE_SIZE, 0, ~0, 878 pagesizes[psind], 0) ? 0 : 879 vm_wait_intr(object); 880 if (error != 0) { 881 VM_OBJECT_WLOCK(object); 882 return (error); 883 } 884 try++; 885 VM_OBJECT_WLOCK(object); 886 continue; 887 } 888 try = 0; 889 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 890 if ((m[i].flags & PG_ZERO) == 0) 891 pmap_zero_page(&m[i]); 892 vm_page_valid(&m[i]); 893 vm_page_xunbusy(&m[i]); 894 } 895 object->size += OFF_TO_IDX(pagesizes[psind]); 896 shmfd->shm_size += pagesizes[psind]; 897 atomic_add_long(&count_largepages[psind], 1); 898 vm_wire_add(atop(pagesizes[psind])); 899 } 900 return (0); 901 } 902 903 static int 904 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 905 { 906 int error; 907 908 VM_OBJECT_WLOCK(shmfd->shm_object); 909 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 910 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 911 rl_cookie); 912 VM_OBJECT_WUNLOCK(shmfd->shm_object); 913 return (error); 914 } 915 916 int 917 shm_dotruncate(struct shmfd *shmfd, off_t length) 918 { 919 void *rl_cookie; 920 int error; 921 922 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 923 &shmfd->shm_mtx); 924 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 925 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 926 return (error); 927 } 928 929 /* 930 * shmfd object management including creation and reference counting 931 * routines. 932 */ 933 struct shmfd * 934 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 935 { 936 struct shmfd *shmfd; 937 vm_object_t obj; 938 939 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 940 shmfd->shm_size = 0; 941 shmfd->shm_uid = ucred->cr_uid; 942 shmfd->shm_gid = ucred->cr_gid; 943 shmfd->shm_mode = mode; 944 if (largepage) { 945 shmfd->shm_object = phys_pager_allocate(NULL, 946 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 947 VM_PROT_DEFAULT, 0, ucred); 948 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 949 } else { 950 obj = vm_pager_allocate(shmfd_pager_type, NULL, 951 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 952 VM_OBJECT_WLOCK(obj); 953 obj->un_pager.swp.swp_priv = shmfd; 954 VM_OBJECT_WUNLOCK(obj); 955 shmfd->shm_object = obj; 956 } 957 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 958 vfs_timestamp(&shmfd->shm_birthtime); 959 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 960 shmfd->shm_birthtime; 961 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 962 refcount_init(&shmfd->shm_refs, 1); 963 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 964 rangelock_init(&shmfd->shm_rl); 965 #ifdef MAC 966 mac_posixshm_init(shmfd); 967 mac_posixshm_create(ucred, shmfd); 968 #endif 969 970 return (shmfd); 971 } 972 973 struct shmfd * 974 shm_hold(struct shmfd *shmfd) 975 { 976 977 refcount_acquire(&shmfd->shm_refs); 978 return (shmfd); 979 } 980 981 void 982 shm_drop(struct shmfd *shmfd) 983 { 984 vm_object_t obj; 985 986 if (refcount_release(&shmfd->shm_refs)) { 987 #ifdef MAC 988 mac_posixshm_destroy(shmfd); 989 #endif 990 rangelock_destroy(&shmfd->shm_rl); 991 mtx_destroy(&shmfd->shm_mtx); 992 obj = shmfd->shm_object; 993 if (!shm_largepage(shmfd)) { 994 VM_OBJECT_WLOCK(obj); 995 obj->un_pager.swp.swp_priv = NULL; 996 VM_OBJECT_WUNLOCK(obj); 997 } 998 vm_object_deallocate(obj); 999 free(shmfd, M_SHMFD); 1000 } 1001 } 1002 1003 /* 1004 * Determine if the credentials have sufficient permissions for a 1005 * specified combination of FREAD and FWRITE. 1006 */ 1007 int 1008 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 1009 { 1010 accmode_t accmode; 1011 int error; 1012 1013 accmode = 0; 1014 if (flags & FREAD) 1015 accmode |= VREAD; 1016 if (flags & FWRITE) 1017 accmode |= VWRITE; 1018 mtx_lock(&shm_timestamp_lock); 1019 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1020 accmode, ucred); 1021 mtx_unlock(&shm_timestamp_lock); 1022 return (error); 1023 } 1024 1025 static void 1026 shm_init(void *arg) 1027 { 1028 char name[32]; 1029 int i; 1030 1031 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 1032 sx_init(&shm_dict_lock, "shm dictionary"); 1033 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 1034 new_unrhdr64(&shm_ino_unr, 1); 1035 shm_dev_ino = devfs_alloc_cdp_inode(); 1036 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 1037 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops, 1038 OBJT_SWAP); 1039 MPASS(shmfd_pager_type != -1); 1040 1041 for (i = 1; i < MAXPAGESIZES; i++) { 1042 if (pagesizes[i] == 0) 1043 break; 1044 #define M (1024 * 1024) 1045 #define G (1024 * M) 1046 if (pagesizes[i] >= G) 1047 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 1048 else if (pagesizes[i] >= M) 1049 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 1050 else 1051 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 1052 #undef G 1053 #undef M 1054 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 1055 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 1056 "number of non-transient largepages allocated"); 1057 } 1058 } 1059 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 1060 1061 /* 1062 * Remove all shared memory objects that belong to a prison. 1063 */ 1064 void 1065 shm_remove_prison(struct prison *pr) 1066 { 1067 struct shm_mapping *shmm, *tshmm; 1068 u_long i; 1069 1070 sx_xlock(&shm_dict_lock); 1071 for (i = 0; i < shm_hash + 1; i++) { 1072 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) { 1073 if (shmm->sm_shmfd->shm_object->cred && 1074 shmm->sm_shmfd->shm_object->cred->cr_prison == pr) 1075 shm_doremove(shmm); 1076 } 1077 } 1078 sx_xunlock(&shm_dict_lock); 1079 } 1080 1081 /* 1082 * Dictionary management. We maintain an in-kernel dictionary to map 1083 * paths to shmfd objects. We use the FNV hash on the path to store 1084 * the mappings in a hash table. 1085 */ 1086 static struct shmfd * 1087 shm_lookup(char *path, Fnv32_t fnv) 1088 { 1089 struct shm_mapping *map; 1090 1091 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1092 if (map->sm_fnv != fnv) 1093 continue; 1094 if (strcmp(map->sm_path, path) == 0) 1095 return (map->sm_shmfd); 1096 } 1097 1098 return (NULL); 1099 } 1100 1101 static void 1102 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 1103 { 1104 struct shm_mapping *map; 1105 1106 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 1107 map->sm_path = path; 1108 map->sm_fnv = fnv; 1109 map->sm_shmfd = shm_hold(shmfd); 1110 shmfd->shm_path = path; 1111 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 1112 } 1113 1114 static int 1115 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1116 { 1117 struct shm_mapping *map; 1118 int error; 1119 1120 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1121 if (map->sm_fnv != fnv) 1122 continue; 1123 if (strcmp(map->sm_path, path) == 0) { 1124 #ifdef MAC 1125 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1126 if (error) 1127 return (error); 1128 #endif 1129 error = shm_access(map->sm_shmfd, ucred, 1130 FREAD | FWRITE); 1131 if (error) 1132 return (error); 1133 shm_doremove(map); 1134 return (0); 1135 } 1136 } 1137 1138 return (ENOENT); 1139 } 1140 1141 static void 1142 shm_doremove(struct shm_mapping *map) 1143 { 1144 map->sm_shmfd->shm_path = NULL; 1145 LIST_REMOVE(map, sm_link); 1146 shm_drop(map->sm_shmfd); 1147 free(map->sm_path, M_SHMFD); 1148 free(map, M_SHMFD); 1149 } 1150 1151 int 1152 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1153 int shmflags, struct filecaps *fcaps, const char *name __unused) 1154 { 1155 struct pwddesc *pdp; 1156 struct shmfd *shmfd; 1157 struct file *fp; 1158 char *path; 1159 void *rl_cookie; 1160 Fnv32_t fnv; 1161 mode_t cmode; 1162 int error, fd, initial_seals; 1163 bool largepage; 1164 1165 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1166 SHM_LARGEPAGE)) != 0) 1167 return (EINVAL); 1168 1169 initial_seals = F_SEAL_SEAL; 1170 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1171 initial_seals &= ~F_SEAL_SEAL; 1172 1173 #ifdef CAPABILITY_MODE 1174 /* 1175 * shm_open(2) is only allowed for anonymous objects. 1176 */ 1177 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1178 return (ECAPMODE); 1179 #endif 1180 1181 AUDIT_ARG_FFLAGS(flags); 1182 AUDIT_ARG_MODE(mode); 1183 1184 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1185 return (EINVAL); 1186 1187 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1188 return (EINVAL); 1189 1190 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1191 if (largepage && !PMAP_HAS_LARGEPAGES) 1192 return (ENOTTY); 1193 1194 /* 1195 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1196 * If the decision is made later to allow additional seals, care must be 1197 * taken below to ensure that the seals are properly set if the shmfd 1198 * already existed -- this currently assumes that only F_SEAL_SEAL can 1199 * be set and doesn't take further precautions to ensure the validity of 1200 * the seals being added with respect to current mappings. 1201 */ 1202 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1203 return (EINVAL); 1204 1205 pdp = td->td_proc->p_pd; 1206 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1207 1208 /* 1209 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1210 * by POSIX. We allow it to be unset here so that an in-kernel 1211 * interface may be written as a thin layer around shm, optionally not 1212 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1213 * in sys_shm_open() to keep this implementation compliant. 1214 */ 1215 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1216 if (error) 1217 return (error); 1218 1219 /* A SHM_ANON path pointer creates an anonymous object. */ 1220 if (userpath == SHM_ANON) { 1221 /* A read-only anonymous object is pointless. */ 1222 if ((flags & O_ACCMODE) == O_RDONLY) { 1223 fdclose(td, fp, fd); 1224 fdrop(fp, td); 1225 return (EINVAL); 1226 } 1227 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1228 shmfd->shm_seals = initial_seals; 1229 shmfd->shm_flags = shmflags; 1230 } else { 1231 error = shm_copyin_path(td, userpath, &path); 1232 if (error != 0) { 1233 fdclose(td, fp, fd); 1234 fdrop(fp, td); 1235 return (error); 1236 } 1237 1238 AUDIT_ARG_UPATH1_CANON(path); 1239 fnv = fnv_32_str(path, FNV1_32_INIT); 1240 sx_xlock(&shm_dict_lock); 1241 shmfd = shm_lookup(path, fnv); 1242 if (shmfd == NULL) { 1243 /* Object does not yet exist, create it if requested. */ 1244 if (flags & O_CREAT) { 1245 #ifdef MAC 1246 error = mac_posixshm_check_create(td->td_ucred, 1247 path); 1248 if (error == 0) { 1249 #endif 1250 shmfd = shm_alloc(td->td_ucred, cmode, 1251 largepage); 1252 shmfd->shm_seals = initial_seals; 1253 shmfd->shm_flags = shmflags; 1254 shm_insert(path, fnv, shmfd); 1255 #ifdef MAC 1256 } 1257 #endif 1258 } else { 1259 free(path, M_SHMFD); 1260 error = ENOENT; 1261 } 1262 } else { 1263 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1264 &shmfd->shm_mtx); 1265 1266 /* 1267 * kern_shm_open() likely shouldn't ever error out on 1268 * trying to set a seal that already exists, unlike 1269 * F_ADD_SEALS. This would break terribly as 1270 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1271 * historical behavior where the underlying file could 1272 * not be sealed. 1273 */ 1274 initial_seals &= ~shmfd->shm_seals; 1275 1276 /* 1277 * Object already exists, obtain a new 1278 * reference if requested and permitted. 1279 */ 1280 free(path, M_SHMFD); 1281 1282 /* 1283 * initial_seals can't set additional seals if we've 1284 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1285 * then we've already removed that one from 1286 * initial_seals. This is currently redundant as we 1287 * only allow setting F_SEAL_SEAL at creation time, but 1288 * it's cheap to check and decreases the effort required 1289 * to allow additional seals. 1290 */ 1291 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1292 initial_seals != 0) 1293 error = EPERM; 1294 else if ((flags & (O_CREAT | O_EXCL)) == 1295 (O_CREAT | O_EXCL)) 1296 error = EEXIST; 1297 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1298 error = EINVAL; 1299 else { 1300 #ifdef MAC 1301 error = mac_posixshm_check_open(td->td_ucred, 1302 shmfd, FFLAGS(flags & O_ACCMODE)); 1303 if (error == 0) 1304 #endif 1305 error = shm_access(shmfd, td->td_ucred, 1306 FFLAGS(flags & O_ACCMODE)); 1307 } 1308 1309 /* 1310 * Truncate the file back to zero length if 1311 * O_TRUNC was specified and the object was 1312 * opened with read/write. 1313 */ 1314 if (error == 0 && 1315 (flags & (O_ACCMODE | O_TRUNC)) == 1316 (O_RDWR | O_TRUNC)) { 1317 VM_OBJECT_WLOCK(shmfd->shm_object); 1318 #ifdef MAC 1319 error = mac_posixshm_check_truncate( 1320 td->td_ucred, fp->f_cred, shmfd); 1321 if (error == 0) 1322 #endif 1323 error = shm_dotruncate_locked(shmfd, 0, 1324 rl_cookie); 1325 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1326 } 1327 if (error == 0) { 1328 /* 1329 * Currently we only allow F_SEAL_SEAL to be 1330 * set initially. As noted above, this would 1331 * need to be reworked should that change. 1332 */ 1333 shmfd->shm_seals |= initial_seals; 1334 shm_hold(shmfd); 1335 } 1336 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 1337 &shmfd->shm_mtx); 1338 } 1339 sx_xunlock(&shm_dict_lock); 1340 1341 if (error) { 1342 fdclose(td, fp, fd); 1343 fdrop(fp, td); 1344 return (error); 1345 } 1346 } 1347 1348 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1349 1350 td->td_retval[0] = fd; 1351 fdrop(fp, td); 1352 1353 return (0); 1354 } 1355 1356 /* System calls. */ 1357 #ifdef COMPAT_FREEBSD12 1358 int 1359 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1360 { 1361 1362 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1363 uap->mode, NULL)); 1364 } 1365 #endif 1366 1367 int 1368 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1369 { 1370 char *path; 1371 Fnv32_t fnv; 1372 int error; 1373 1374 error = shm_copyin_path(td, uap->path, &path); 1375 if (error != 0) 1376 return (error); 1377 1378 AUDIT_ARG_UPATH1_CANON(path); 1379 fnv = fnv_32_str(path, FNV1_32_INIT); 1380 sx_xlock(&shm_dict_lock); 1381 error = shm_remove(path, fnv, td->td_ucred); 1382 sx_xunlock(&shm_dict_lock); 1383 free(path, M_SHMFD); 1384 1385 return (error); 1386 } 1387 1388 int 1389 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1390 { 1391 char *path_from = NULL, *path_to = NULL; 1392 Fnv32_t fnv_from, fnv_to; 1393 struct shmfd *fd_from; 1394 struct shmfd *fd_to; 1395 int error; 1396 int flags; 1397 1398 flags = uap->flags; 1399 AUDIT_ARG_FFLAGS(flags); 1400 1401 /* 1402 * Make sure the user passed only valid flags. 1403 * If you add a new flag, please add a new term here. 1404 */ 1405 if ((flags & ~( 1406 SHM_RENAME_NOREPLACE | 1407 SHM_RENAME_EXCHANGE 1408 )) != 0) { 1409 error = EINVAL; 1410 goto out; 1411 } 1412 1413 /* 1414 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1415 * force the user to choose one or the other. 1416 */ 1417 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1418 (flags & SHM_RENAME_EXCHANGE) != 0) { 1419 error = EINVAL; 1420 goto out; 1421 } 1422 1423 /* Renaming to or from anonymous makes no sense */ 1424 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1425 error = EINVAL; 1426 goto out; 1427 } 1428 1429 error = shm_copyin_path(td, uap->path_from, &path_from); 1430 if (error != 0) 1431 goto out; 1432 1433 error = shm_copyin_path(td, uap->path_to, &path_to); 1434 if (error != 0) 1435 goto out; 1436 1437 AUDIT_ARG_UPATH1_CANON(path_from); 1438 AUDIT_ARG_UPATH2_CANON(path_to); 1439 1440 /* Rename with from/to equal is a no-op */ 1441 if (strcmp(path_from, path_to) == 0) 1442 goto out; 1443 1444 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1445 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1446 1447 sx_xlock(&shm_dict_lock); 1448 1449 fd_from = shm_lookup(path_from, fnv_from); 1450 if (fd_from == NULL) { 1451 error = ENOENT; 1452 goto out_locked; 1453 } 1454 1455 fd_to = shm_lookup(path_to, fnv_to); 1456 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1457 error = EEXIST; 1458 goto out_locked; 1459 } 1460 1461 /* 1462 * Unconditionally prevents shm_remove from invalidating the 'from' 1463 * shm's state. 1464 */ 1465 shm_hold(fd_from); 1466 error = shm_remove(path_from, fnv_from, td->td_ucred); 1467 1468 /* 1469 * One of my assumptions failed if ENOENT (e.g. locking didn't 1470 * protect us) 1471 */ 1472 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1473 path_from)); 1474 if (error != 0) { 1475 shm_drop(fd_from); 1476 goto out_locked; 1477 } 1478 1479 /* 1480 * If we are exchanging, we need to ensure the shm_remove below 1481 * doesn't invalidate the dest shm's state. 1482 */ 1483 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1484 shm_hold(fd_to); 1485 1486 /* 1487 * NOTE: if path_to is not already in the hash, c'est la vie; 1488 * it simply means we have nothing already at path_to to unlink. 1489 * That is the ENOENT case. 1490 * 1491 * If we somehow don't have access to unlink this guy, but 1492 * did for the shm at path_from, then relink the shm to path_from 1493 * and abort with EACCES. 1494 * 1495 * All other errors: that is weird; let's relink and abort the 1496 * operation. 1497 */ 1498 error = shm_remove(path_to, fnv_to, td->td_ucred); 1499 if (error != 0 && error != ENOENT) { 1500 shm_insert(path_from, fnv_from, fd_from); 1501 shm_drop(fd_from); 1502 /* Don't free path_from now, since the hash references it */ 1503 path_from = NULL; 1504 goto out_locked; 1505 } 1506 1507 error = 0; 1508 1509 shm_insert(path_to, fnv_to, fd_from); 1510 1511 /* Don't free path_to now, since the hash references it */ 1512 path_to = NULL; 1513 1514 /* We kept a ref when we removed, and incremented again in insert */ 1515 shm_drop(fd_from); 1516 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1517 fd_from->shm_refs)); 1518 1519 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1520 shm_insert(path_from, fnv_from, fd_to); 1521 path_from = NULL; 1522 shm_drop(fd_to); 1523 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1524 fd_to->shm_refs)); 1525 } 1526 1527 out_locked: 1528 sx_xunlock(&shm_dict_lock); 1529 1530 out: 1531 free(path_from, M_SHMFD); 1532 free(path_to, M_SHMFD); 1533 return (error); 1534 } 1535 1536 static int 1537 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1538 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1539 vm_ooffset_t foff, struct thread *td) 1540 { 1541 struct vmspace *vms; 1542 vm_map_entry_t next_entry, prev_entry; 1543 vm_offset_t align, mask, maxaddr; 1544 int docow, error, rv, try; 1545 bool curmap; 1546 1547 if (shmfd->shm_lp_psind == 0) 1548 return (EINVAL); 1549 1550 /* MAP_PRIVATE is disabled */ 1551 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1552 MAP_NOCORE | 1553 #ifdef MAP_32BIT 1554 MAP_32BIT | 1555 #endif 1556 MAP_ALIGNMENT_MASK)) != 0) 1557 return (EINVAL); 1558 1559 vms = td->td_proc->p_vmspace; 1560 curmap = map == &vms->vm_map; 1561 if (curmap) { 1562 error = kern_mmap_racct_check(td, map, size); 1563 if (error != 0) 1564 return (error); 1565 } 1566 1567 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1568 docow |= MAP_INHERIT_SHARE; 1569 if ((flags & MAP_NOCORE) != 0) 1570 docow |= MAP_DISABLE_COREDUMP; 1571 1572 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1573 if ((foff & mask) != 0) 1574 return (EINVAL); 1575 maxaddr = vm_map_max(map); 1576 #ifdef MAP_32BIT 1577 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1578 maxaddr = MAP_32BIT_MAX_ADDR; 1579 #endif 1580 if (size == 0 || (size & mask) != 0 || 1581 (*addr != 0 && ((*addr & mask) != 0 || 1582 *addr + size < *addr || *addr + size > maxaddr))) 1583 return (EINVAL); 1584 1585 align = flags & MAP_ALIGNMENT_MASK; 1586 if (align == 0) { 1587 align = pagesizes[shmfd->shm_lp_psind]; 1588 } else if (align == MAP_ALIGNED_SUPER) { 1589 if (shmfd->shm_lp_psind != 1) 1590 return (EINVAL); 1591 align = pagesizes[1]; 1592 } else { 1593 align >>= MAP_ALIGNMENT_SHIFT; 1594 align = 1ULL << align; 1595 /* Also handles overflow. */ 1596 if (align < pagesizes[shmfd->shm_lp_psind]) 1597 return (EINVAL); 1598 } 1599 1600 vm_map_lock(map); 1601 if ((flags & MAP_FIXED) == 0) { 1602 try = 1; 1603 if (curmap && (*addr == 0 || 1604 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1605 *addr < round_page((vm_offset_t)vms->vm_daddr + 1606 lim_max(td, RLIMIT_DATA))))) { 1607 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1608 lim_max(td, RLIMIT_DATA), 1609 pagesizes[shmfd->shm_lp_psind]); 1610 } 1611 again: 1612 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1613 if (rv != KERN_SUCCESS) { 1614 if (try == 1) { 1615 try = 2; 1616 *addr = vm_map_min(map); 1617 if ((*addr & mask) != 0) 1618 *addr = (*addr + mask) & mask; 1619 goto again; 1620 } 1621 goto fail1; 1622 } 1623 } else if ((flags & MAP_EXCL) == 0) { 1624 rv = vm_map_delete(map, *addr, *addr + size); 1625 if (rv != KERN_SUCCESS) 1626 goto fail1; 1627 } else { 1628 error = ENOSPC; 1629 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1630 goto fail; 1631 next_entry = vm_map_entry_succ(prev_entry); 1632 if (next_entry->start < *addr + size) 1633 goto fail; 1634 } 1635 1636 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1637 prot, max_prot, docow); 1638 fail1: 1639 error = vm_mmap_to_errno(rv); 1640 fail: 1641 vm_map_unlock(map); 1642 return (error); 1643 } 1644 1645 static int 1646 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1647 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1648 vm_ooffset_t foff, struct thread *td) 1649 { 1650 struct shmfd *shmfd; 1651 vm_prot_t maxprot; 1652 int error; 1653 bool writecnt; 1654 void *rl_cookie; 1655 1656 shmfd = fp->f_data; 1657 maxprot = VM_PROT_NONE; 1658 1659 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1660 &shmfd->shm_mtx); 1661 /* FREAD should always be set. */ 1662 if ((fp->f_flag & FREAD) != 0) 1663 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1664 1665 /* 1666 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1667 * mapping with a write seal applied. Private mappings are always 1668 * writeable. 1669 */ 1670 if ((flags & MAP_SHARED) == 0) { 1671 cap_maxprot |= VM_PROT_WRITE; 1672 maxprot |= VM_PROT_WRITE; 1673 writecnt = false; 1674 } else { 1675 if ((fp->f_flag & FWRITE) != 0 && 1676 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1677 maxprot |= VM_PROT_WRITE; 1678 1679 /* 1680 * Any mappings from a writable descriptor may be upgraded to 1681 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1682 * applied between the open and subsequent mmap(2). We want to 1683 * reject application of a write seal as long as any such 1684 * mapping exists so that the seal cannot be trivially bypassed. 1685 */ 1686 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1687 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1688 error = EACCES; 1689 goto out; 1690 } 1691 } 1692 maxprot &= cap_maxprot; 1693 1694 /* See comment in vn_mmap(). */ 1695 if ( 1696 #ifdef _LP64 1697 objsize > OFF_MAX || 1698 #endif 1699 foff > OFF_MAX - objsize) { 1700 error = EINVAL; 1701 goto out; 1702 } 1703 1704 #ifdef MAC 1705 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1706 if (error != 0) 1707 goto out; 1708 #endif 1709 1710 mtx_lock(&shm_timestamp_lock); 1711 vfs_timestamp(&shmfd->shm_atime); 1712 mtx_unlock(&shm_timestamp_lock); 1713 vm_object_reference(shmfd->shm_object); 1714 1715 if (shm_largepage(shmfd)) { 1716 writecnt = false; 1717 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1718 maxprot, flags, foff, td); 1719 } else { 1720 if (writecnt) { 1721 vm_pager_update_writecount(shmfd->shm_object, 0, 1722 objsize); 1723 } 1724 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1725 shmfd->shm_object, foff, writecnt, td); 1726 } 1727 if (error != 0) { 1728 if (writecnt) 1729 vm_pager_release_writecount(shmfd->shm_object, 0, 1730 objsize); 1731 vm_object_deallocate(shmfd->shm_object); 1732 } 1733 out: 1734 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1735 return (error); 1736 } 1737 1738 static int 1739 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1740 struct thread *td) 1741 { 1742 struct shmfd *shmfd; 1743 int error; 1744 1745 error = 0; 1746 shmfd = fp->f_data; 1747 mtx_lock(&shm_timestamp_lock); 1748 /* 1749 * SUSv4 says that x bits of permission need not be affected. 1750 * Be consistent with our shm_open there. 1751 */ 1752 #ifdef MAC 1753 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1754 if (error != 0) 1755 goto out; 1756 #endif 1757 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1758 VADMIN, active_cred); 1759 if (error != 0) 1760 goto out; 1761 shmfd->shm_mode = mode & ACCESSPERMS; 1762 out: 1763 mtx_unlock(&shm_timestamp_lock); 1764 return (error); 1765 } 1766 1767 static int 1768 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1769 struct thread *td) 1770 { 1771 struct shmfd *shmfd; 1772 int error; 1773 1774 error = 0; 1775 shmfd = fp->f_data; 1776 mtx_lock(&shm_timestamp_lock); 1777 #ifdef MAC 1778 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1779 if (error != 0) 1780 goto out; 1781 #endif 1782 if (uid == (uid_t)-1) 1783 uid = shmfd->shm_uid; 1784 if (gid == (gid_t)-1) 1785 gid = shmfd->shm_gid; 1786 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1787 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1788 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1789 goto out; 1790 shmfd->shm_uid = uid; 1791 shmfd->shm_gid = gid; 1792 out: 1793 mtx_unlock(&shm_timestamp_lock); 1794 return (error); 1795 } 1796 1797 /* 1798 * Helper routines to allow the backing object of a shared memory file 1799 * descriptor to be mapped in the kernel. 1800 */ 1801 int 1802 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1803 { 1804 struct shmfd *shmfd; 1805 vm_offset_t kva, ofs; 1806 vm_object_t obj; 1807 int rv; 1808 1809 if (fp->f_type != DTYPE_SHM) 1810 return (EINVAL); 1811 shmfd = fp->f_data; 1812 obj = shmfd->shm_object; 1813 VM_OBJECT_WLOCK(obj); 1814 /* 1815 * XXXRW: This validation is probably insufficient, and subject to 1816 * sign errors. It should be fixed. 1817 */ 1818 if (offset >= shmfd->shm_size || 1819 offset + size > round_page(shmfd->shm_size)) { 1820 VM_OBJECT_WUNLOCK(obj); 1821 return (EINVAL); 1822 } 1823 1824 shmfd->shm_kmappings++; 1825 vm_object_reference_locked(obj); 1826 VM_OBJECT_WUNLOCK(obj); 1827 1828 /* Map the object into the kernel_map and wire it. */ 1829 kva = vm_map_min(kernel_map); 1830 ofs = offset & PAGE_MASK; 1831 offset = trunc_page(offset); 1832 size = round_page(size + ofs); 1833 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1834 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1835 VM_PROT_READ | VM_PROT_WRITE, 0); 1836 if (rv == KERN_SUCCESS) { 1837 rv = vm_map_wire(kernel_map, kva, kva + size, 1838 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1839 if (rv == KERN_SUCCESS) { 1840 *memp = (void *)(kva + ofs); 1841 return (0); 1842 } 1843 vm_map_remove(kernel_map, kva, kva + size); 1844 } else 1845 vm_object_deallocate(obj); 1846 1847 /* On failure, drop our mapping reference. */ 1848 VM_OBJECT_WLOCK(obj); 1849 shmfd->shm_kmappings--; 1850 VM_OBJECT_WUNLOCK(obj); 1851 1852 return (vm_mmap_to_errno(rv)); 1853 } 1854 1855 /* 1856 * We require the caller to unmap the entire entry. This allows us to 1857 * safely decrement shm_kmappings when a mapping is removed. 1858 */ 1859 int 1860 shm_unmap(struct file *fp, void *mem, size_t size) 1861 { 1862 struct shmfd *shmfd; 1863 vm_map_entry_t entry; 1864 vm_offset_t kva, ofs; 1865 vm_object_t obj; 1866 vm_pindex_t pindex; 1867 vm_prot_t prot; 1868 boolean_t wired; 1869 vm_map_t map; 1870 int rv; 1871 1872 if (fp->f_type != DTYPE_SHM) 1873 return (EINVAL); 1874 shmfd = fp->f_data; 1875 kva = (vm_offset_t)mem; 1876 ofs = kva & PAGE_MASK; 1877 kva = trunc_page(kva); 1878 size = round_page(size + ofs); 1879 map = kernel_map; 1880 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1881 &obj, &pindex, &prot, &wired); 1882 if (rv != KERN_SUCCESS) 1883 return (EINVAL); 1884 if (entry->start != kva || entry->end != kva + size) { 1885 vm_map_lookup_done(map, entry); 1886 return (EINVAL); 1887 } 1888 vm_map_lookup_done(map, entry); 1889 if (obj != shmfd->shm_object) 1890 return (EINVAL); 1891 vm_map_remove(map, kva, kva + size); 1892 VM_OBJECT_WLOCK(obj); 1893 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1894 shmfd->shm_kmappings--; 1895 VM_OBJECT_WUNLOCK(obj); 1896 return (0); 1897 } 1898 1899 static int 1900 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1901 { 1902 const char *path, *pr_path; 1903 size_t pr_pathlen; 1904 bool visible; 1905 1906 sx_assert(&shm_dict_lock, SA_LOCKED); 1907 kif->kf_type = KF_TYPE_SHM; 1908 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1909 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1910 if (shmfd->shm_path != NULL) { 1911 if (shmfd->shm_path != NULL) { 1912 path = shmfd->shm_path; 1913 pr_path = curthread->td_ucred->cr_prison->pr_path; 1914 if (strcmp(pr_path, "/") != 0) { 1915 /* Return the jail-rooted pathname. */ 1916 pr_pathlen = strlen(pr_path); 1917 visible = strncmp(path, pr_path, pr_pathlen) 1918 == 0 && path[pr_pathlen] == '/'; 1919 if (list && !visible) 1920 return (EPERM); 1921 if (visible) 1922 path += pr_pathlen; 1923 } 1924 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1925 } 1926 } 1927 return (0); 1928 } 1929 1930 static int 1931 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1932 struct filedesc *fdp __unused) 1933 { 1934 int res; 1935 1936 sx_slock(&shm_dict_lock); 1937 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1938 sx_sunlock(&shm_dict_lock); 1939 return (res); 1940 } 1941 1942 static int 1943 shm_add_seals(struct file *fp, int seals) 1944 { 1945 struct shmfd *shmfd; 1946 void *rl_cookie; 1947 vm_ooffset_t writemappings; 1948 int error, nseals; 1949 1950 error = 0; 1951 shmfd = fp->f_data; 1952 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1953 &shmfd->shm_mtx); 1954 1955 /* Even already-set seals should result in EPERM. */ 1956 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1957 error = EPERM; 1958 goto out; 1959 } 1960 nseals = seals & ~shmfd->shm_seals; 1961 if ((nseals & F_SEAL_WRITE) != 0) { 1962 if (shm_largepage(shmfd)) { 1963 error = ENOTSUP; 1964 goto out; 1965 } 1966 1967 /* 1968 * The rangelock above prevents writable mappings from being 1969 * added after we've started applying seals. The RLOCK here 1970 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1971 * writemappings will be done without a rangelock. 1972 */ 1973 VM_OBJECT_RLOCK(shmfd->shm_object); 1974 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1975 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1976 /* kmappings are also writable */ 1977 if (writemappings > 0) { 1978 error = EBUSY; 1979 goto out; 1980 } 1981 } 1982 shmfd->shm_seals |= nseals; 1983 out: 1984 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1985 return (error); 1986 } 1987 1988 static int 1989 shm_get_seals(struct file *fp, int *seals) 1990 { 1991 struct shmfd *shmfd; 1992 1993 shmfd = fp->f_data; 1994 *seals = shmfd->shm_seals; 1995 return (0); 1996 } 1997 1998 static int 1999 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 2000 { 2001 vm_object_t object; 2002 vm_pindex_t pistart, pi, piend; 2003 vm_ooffset_t off, len; 2004 int startofs, endofs, end; 2005 int error; 2006 2007 off = *offset; 2008 len = *length; 2009 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 2010 if (off + len > shmfd->shm_size) 2011 len = shmfd->shm_size - off; 2012 object = shmfd->shm_object; 2013 startofs = off & PAGE_MASK; 2014 endofs = (off + len) & PAGE_MASK; 2015 pistart = OFF_TO_IDX(off); 2016 piend = OFF_TO_IDX(off + len); 2017 pi = OFF_TO_IDX(off + PAGE_MASK); 2018 error = 0; 2019 2020 /* Handle the case when offset is on or beyond shm size. */ 2021 if ((off_t)len <= 0) { 2022 *length = 0; 2023 return (0); 2024 } 2025 2026 VM_OBJECT_WLOCK(object); 2027 2028 if (startofs != 0) { 2029 end = pistart != piend ? PAGE_SIZE : endofs; 2030 error = shm_partial_page_invalidate(object, pistart, startofs, 2031 end); 2032 if (error) 2033 goto out; 2034 off += end - startofs; 2035 len -= end - startofs; 2036 } 2037 2038 if (pi < piend) { 2039 vm_object_page_remove(object, pi, piend, 0); 2040 off += IDX_TO_OFF(piend - pi); 2041 len -= IDX_TO_OFF(piend - pi); 2042 } 2043 2044 if (endofs != 0 && pistart != piend) { 2045 error = shm_partial_page_invalidate(object, piend, 0, endofs); 2046 if (error) 2047 goto out; 2048 off += endofs; 2049 len -= endofs; 2050 } 2051 2052 out: 2053 VM_OBJECT_WUNLOCK(shmfd->shm_object); 2054 *offset = off; 2055 *length = len; 2056 return (error); 2057 } 2058 2059 static int 2060 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 2061 struct ucred *active_cred, struct thread *td) 2062 { 2063 void *rl_cookie; 2064 struct shmfd *shmfd; 2065 off_t off, len; 2066 int error; 2067 2068 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd")); 2069 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0, 2070 ("shm_fspacectl: non-zero flags")); 2071 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset, 2072 ("shm_fspacectl: offset/length overflow or underflow")); 2073 error = EINVAL; 2074 shmfd = fp->f_data; 2075 off = *offset; 2076 len = *length; 2077 2078 rl_cookie = rangelock_wlock(&shmfd->shm_rl, off, off + len, 2079 &shmfd->shm_mtx); 2080 switch (cmd) { 2081 case SPACECTL_DEALLOC: 2082 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2083 error = EPERM; 2084 break; 2085 } 2086 error = shm_deallocate(shmfd, &off, &len, flags); 2087 *offset = off; 2088 *length = len; 2089 break; 2090 default: 2091 __assert_unreachable(); 2092 } 2093 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 2094 return (error); 2095 } 2096 2097 2098 static int 2099 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2100 { 2101 void *rl_cookie; 2102 struct shmfd *shmfd; 2103 size_t size; 2104 int error; 2105 2106 /* This assumes that the caller already checked for overflow. */ 2107 error = 0; 2108 shmfd = fp->f_data; 2109 size = offset + len; 2110 2111 /* 2112 * Just grab the rangelock for the range that we may be attempting to 2113 * grow, rather than blocking read/write for regions we won't be 2114 * touching while this (potential) resize is in progress. Other 2115 * attempts to resize the shmfd will have to take a write lock from 0 to 2116 * OFF_MAX, so this being potentially beyond the current usable range of 2117 * the shmfd is not necessarily a concern. If other mechanisms are 2118 * added to grow a shmfd, this may need to be re-evaluated. 2119 */ 2120 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 2121 &shmfd->shm_mtx); 2122 if (size > shmfd->shm_size) 2123 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2124 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 2125 /* Translate to posix_fallocate(2) return value as needed. */ 2126 if (error == ENOMEM) 2127 error = ENOSPC; 2128 return (error); 2129 } 2130 2131 static int 2132 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2133 { 2134 struct shm_mapping *shmm; 2135 struct sbuf sb; 2136 struct kinfo_file kif; 2137 u_long i; 2138 int error, error2; 2139 2140 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2141 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2142 error = 0; 2143 sx_slock(&shm_dict_lock); 2144 for (i = 0; i < shm_hash + 1; i++) { 2145 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2146 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2147 &kif, true); 2148 if (error == EPERM) { 2149 error = 0; 2150 continue; 2151 } 2152 if (error != 0) 2153 break; 2154 pack_kinfo(&kif); 2155 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2156 0 : ENOMEM; 2157 if (error != 0) 2158 break; 2159 } 2160 } 2161 sx_sunlock(&shm_dict_lock); 2162 error2 = sbuf_finish(&sb); 2163 sbuf_delete(&sb); 2164 return (error != 0 ? error : error2); 2165 } 2166 2167 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2168 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2169 NULL, 0, sysctl_posix_shm_list, "", 2170 "POSIX SHM list"); 2171 2172 int 2173 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2174 struct filecaps *caps) 2175 { 2176 2177 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2178 } 2179 2180 /* 2181 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2182 * caller, and libc will enforce it for the traditional shm_open() call. This 2183 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2184 * interface also includes a 'name' argument that is currently unused, but could 2185 * potentially be exported later via some interface for debugging purposes. 2186 * From the kernel's perspective, it is optional. Individual consumers like 2187 * memfd_create() may require it in order to be compatible with other systems 2188 * implementing the same function. 2189 */ 2190 int 2191 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2192 { 2193 2194 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2195 uap->shmflags, NULL, uap->name)); 2196 }
Cache object: f10dba62a5e552dfa3ce48a884ec264f
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