1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 5 * Copyright 2020 The FreeBSD Foundation 6 * All rights reserved. 7 * 8 * Portions of this software were developed by BAE Systems, the University of 9 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 10 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 11 * Computing (TC) research program. 12 * 13 * Portions of this software were developed by Konstantin Belousov 14 * under sponsorship from the FreeBSD Foundation. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38 /* 39 * Support for shared swap-backed anonymous memory objects via 40 * shm_open(2), shm_rename(2), and shm_unlink(2). 41 * While most of the implementation is here, vm_mmap.c contains 42 * mapping logic changes. 43 * 44 * posixshmcontrol(1) allows users to inspect the state of the memory 45 * objects. Per-uid swap resource limit controls total amount of 46 * memory that user can consume for anonymous objects, including 47 * shared. 48 */ 49 50 #include <sys/cdefs.h> 51 #include "opt_capsicum.h" 52 #include "opt_ktrace.h" 53 54 #include <sys/param.h> 55 #include <sys/capsicum.h> 56 #include <sys/conf.h> 57 #include <sys/fcntl.h> 58 #include <sys/file.h> 59 #include <sys/filedesc.h> 60 #include <sys/filio.h> 61 #include <sys/fnv_hash.h> 62 #include <sys/kernel.h> 63 #include <sys/limits.h> 64 #include <sys/uio.h> 65 #include <sys/signal.h> 66 #include <sys/jail.h> 67 #include <sys/ktrace.h> 68 #include <sys/lock.h> 69 #include <sys/malloc.h> 70 #include <sys/mman.h> 71 #include <sys/mutex.h> 72 #include <sys/priv.h> 73 #include <sys/proc.h> 74 #include <sys/refcount.h> 75 #include <sys/resourcevar.h> 76 #include <sys/rwlock.h> 77 #include <sys/sbuf.h> 78 #include <sys/stat.h> 79 #include <sys/syscallsubr.h> 80 #include <sys/sysctl.h> 81 #include <sys/sysproto.h> 82 #include <sys/systm.h> 83 #include <sys/sx.h> 84 #include <sys/time.h> 85 #include <sys/vmmeter.h> 86 #include <sys/vnode.h> 87 #include <sys/unistd.h> 88 #include <sys/user.h> 89 90 #include <security/audit/audit.h> 91 #include <security/mac/mac_framework.h> 92 93 #include <vm/vm.h> 94 #include <vm/vm_param.h> 95 #include <vm/pmap.h> 96 #include <vm/vm_extern.h> 97 #include <vm/vm_map.h> 98 #include <vm/vm_kern.h> 99 #include <vm/vm_object.h> 100 #include <vm/vm_page.h> 101 #include <vm/vm_pageout.h> 102 #include <vm/vm_pager.h> 103 #include <vm/swap_pager.h> 104 105 struct shm_mapping { 106 char *sm_path; 107 Fnv32_t sm_fnv; 108 struct shmfd *sm_shmfd; 109 LIST_ENTRY(shm_mapping) sm_link; 110 }; 111 112 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 113 static LIST_HEAD(, shm_mapping) *shm_dictionary; 114 static struct sx shm_dict_lock; 115 static struct mtx shm_timestamp_lock; 116 static u_long shm_hash; 117 static struct unrhdr64 shm_ino_unr; 118 static dev_t shm_dev_ino; 119 120 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 121 122 static void shm_init(void *arg); 123 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 124 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 125 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 126 static void shm_doremove(struct shm_mapping *map); 127 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 128 void *rl_cookie); 129 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 130 void *rl_cookie); 131 static int shm_copyin_path(struct thread *td, const char *userpath_in, 132 char **path_out); 133 static int shm_deallocate(struct shmfd *shmfd, off_t *offset, 134 off_t *length, int flags); 135 136 static fo_rdwr_t shm_read; 137 static fo_rdwr_t shm_write; 138 static fo_truncate_t shm_truncate; 139 static fo_ioctl_t shm_ioctl; 140 static fo_stat_t shm_stat; 141 static fo_close_t shm_close; 142 static fo_chmod_t shm_chmod; 143 static fo_chown_t shm_chown; 144 static fo_seek_t shm_seek; 145 static fo_fill_kinfo_t shm_fill_kinfo; 146 static fo_mmap_t shm_mmap; 147 static fo_get_seals_t shm_get_seals; 148 static fo_add_seals_t shm_add_seals; 149 static fo_fallocate_t shm_fallocate; 150 static fo_fspacectl_t shm_fspacectl; 151 152 /* File descriptor operations. */ 153 struct fileops shm_ops = { 154 .fo_read = shm_read, 155 .fo_write = shm_write, 156 .fo_truncate = shm_truncate, 157 .fo_ioctl = shm_ioctl, 158 .fo_poll = invfo_poll, 159 .fo_kqfilter = invfo_kqfilter, 160 .fo_stat = shm_stat, 161 .fo_close = shm_close, 162 .fo_chmod = shm_chmod, 163 .fo_chown = shm_chown, 164 .fo_sendfile = vn_sendfile, 165 .fo_seek = shm_seek, 166 .fo_fill_kinfo = shm_fill_kinfo, 167 .fo_mmap = shm_mmap, 168 .fo_get_seals = shm_get_seals, 169 .fo_add_seals = shm_add_seals, 170 .fo_fallocate = shm_fallocate, 171 .fo_fspacectl = shm_fspacectl, 172 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 173 }; 174 175 FEATURE(posix_shm, "POSIX shared memory"); 176 177 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 178 ""); 179 180 static int largepage_reclaim_tries = 1; 181 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 182 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 183 "Number of contig reclaims before giving up for default alloc policy"); 184 185 #define shm_rangelock_unlock(shmfd, cookie) \ 186 rangelock_unlock(&(shmfd)->shm_rl, (cookie), &(shmfd)->shm_mtx) 187 #define shm_rangelock_rlock(shmfd, start, end) \ 188 rangelock_rlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx) 189 #define shm_rangelock_tryrlock(shmfd, start, end) \ 190 rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx) 191 #define shm_rangelock_wlock(shmfd, start, end) \ 192 rangelock_wlock(&(shmfd)->shm_rl, (start), (end), &(shmfd)->shm_mtx) 193 194 static int 195 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 196 { 197 vm_page_t m; 198 vm_pindex_t idx; 199 size_t tlen; 200 int error, offset, rv; 201 202 idx = OFF_TO_IDX(uio->uio_offset); 203 offset = uio->uio_offset & PAGE_MASK; 204 tlen = MIN(PAGE_SIZE - offset, len); 205 206 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 207 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 208 if (rv == VM_PAGER_OK) 209 goto found; 210 211 /* 212 * Read I/O without either a corresponding resident page or swap 213 * page: use zero_region. This is intended to avoid instantiating 214 * pages on read from a sparse region. 215 */ 216 VM_OBJECT_WLOCK(obj); 217 m = vm_page_lookup(obj, idx); 218 if (uio->uio_rw == UIO_READ && m == NULL && 219 !vm_pager_has_page(obj, idx, NULL, NULL)) { 220 VM_OBJECT_WUNLOCK(obj); 221 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 222 } 223 224 /* 225 * Although the tmpfs vnode lock is held here, it is 226 * nonetheless safe to sleep waiting for a free page. The 227 * pageout daemon does not need to acquire the tmpfs vnode 228 * lock to page out tobj's pages because tobj is a OBJT_SWAP 229 * type object. 230 */ 231 rv = vm_page_grab_valid(&m, obj, idx, 232 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 233 if (rv != VM_PAGER_OK) { 234 VM_OBJECT_WUNLOCK(obj); 235 if (bootverbose) { 236 printf("uiomove_object: vm_obj %p idx %jd " 237 "pager error %d\n", obj, idx, rv); 238 } 239 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO); 240 } 241 VM_OBJECT_WUNLOCK(obj); 242 243 found: 244 error = uiomove_fromphys(&m, offset, tlen, uio); 245 if (uio->uio_rw == UIO_WRITE && error == 0) 246 vm_page_set_dirty(m); 247 vm_page_activate(m); 248 vm_page_sunbusy(m); 249 250 return (error); 251 } 252 253 int 254 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 255 { 256 ssize_t resid; 257 size_t len; 258 int error; 259 260 error = 0; 261 while ((resid = uio->uio_resid) > 0) { 262 if (obj_size <= uio->uio_offset) 263 break; 264 len = MIN(obj_size - uio->uio_offset, resid); 265 if (len == 0) 266 break; 267 error = uiomove_object_page(obj, len, uio); 268 if (error != 0 || resid == uio->uio_resid) 269 break; 270 } 271 return (error); 272 } 273 274 static u_long count_largepages[MAXPAGESIZES]; 275 276 static int 277 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 278 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 279 { 280 vm_page_t m __diagused; 281 int psind; 282 283 psind = object->un_pager.phys.data_val; 284 if (psind == 0 || pidx >= object->size) 285 return (VM_PAGER_FAIL); 286 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 287 288 /* 289 * We only busy the first page in the superpage run. It is 290 * useless to busy whole run since we only remove full 291 * superpage, and it takes too long to busy e.g. 512 * 512 == 292 * 262144 pages constituing 1G amd64 superage. 293 */ 294 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 295 MPASS(m != NULL); 296 297 *last = *first + atop(pagesizes[psind]) - 1; 298 return (VM_PAGER_OK); 299 } 300 301 static boolean_t 302 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 303 int *before, int *after) 304 { 305 int psind; 306 307 psind = object->un_pager.phys.data_val; 308 if (psind == 0 || pindex >= object->size) 309 return (FALSE); 310 if (before != NULL) { 311 *before = pindex - rounddown2(pindex, pagesizes[psind] / 312 PAGE_SIZE); 313 } 314 if (after != NULL) { 315 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 316 pindex; 317 } 318 return (TRUE); 319 } 320 321 static void 322 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 323 vm_ooffset_t foff, struct ucred *cred) 324 { 325 } 326 327 static void 328 shm_largepage_phys_dtor(vm_object_t object) 329 { 330 int psind; 331 332 psind = object->un_pager.phys.data_val; 333 if (psind != 0) { 334 atomic_subtract_long(&count_largepages[psind], 335 object->size / (pagesizes[psind] / PAGE_SIZE)); 336 vm_wire_sub(object->size); 337 } else { 338 KASSERT(object->size == 0, 339 ("largepage phys obj %p not initialized bit size %#jx > 0", 340 object, (uintmax_t)object->size)); 341 } 342 } 343 344 static const struct phys_pager_ops shm_largepage_phys_ops = { 345 .phys_pg_populate = shm_largepage_phys_populate, 346 .phys_pg_haspage = shm_largepage_phys_haspage, 347 .phys_pg_ctor = shm_largepage_phys_ctor, 348 .phys_pg_dtor = shm_largepage_phys_dtor, 349 }; 350 351 bool 352 shm_largepage(struct shmfd *shmfd) 353 { 354 return (shmfd->shm_object->type == OBJT_PHYS); 355 } 356 357 static void 358 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size) 359 { 360 struct shmfd *shm; 361 vm_size_t c; 362 363 swap_pager_freespace(obj, start, size, &c); 364 if (c == 0) 365 return; 366 367 shm = obj->un_pager.swp.swp_priv; 368 if (shm == NULL) 369 return; 370 KASSERT(shm->shm_pages >= c, 371 ("shm %p pages %jd free %jd", shm, 372 (uintmax_t)shm->shm_pages, (uintmax_t)c)); 373 shm->shm_pages -= c; 374 } 375 376 static void 377 shm_page_inserted(vm_object_t obj, vm_page_t m) 378 { 379 struct shmfd *shm; 380 381 shm = obj->un_pager.swp.swp_priv; 382 if (shm == NULL) 383 return; 384 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) 385 shm->shm_pages += 1; 386 } 387 388 static void 389 shm_page_removed(vm_object_t obj, vm_page_t m) 390 { 391 struct shmfd *shm; 392 393 shm = obj->un_pager.swp.swp_priv; 394 if (shm == NULL) 395 return; 396 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) { 397 KASSERT(shm->shm_pages >= 1, 398 ("shm %p pages %jd free 1", shm, 399 (uintmax_t)shm->shm_pages)); 400 shm->shm_pages -= 1; 401 } 402 } 403 404 static struct pagerops shm_swap_pager_ops = { 405 .pgo_kvme_type = KVME_TYPE_SWAP, 406 .pgo_freespace = shm_pager_freespace, 407 .pgo_page_inserted = shm_page_inserted, 408 .pgo_page_removed = shm_page_removed, 409 }; 410 static int shmfd_pager_type = -1; 411 412 static int 413 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 414 { 415 struct shmfd *shmfd; 416 off_t foffset; 417 int error; 418 419 shmfd = fp->f_data; 420 foffset = foffset_lock(fp, 0); 421 error = 0; 422 switch (whence) { 423 case L_INCR: 424 if (foffset < 0 || 425 (offset > 0 && foffset > OFF_MAX - offset)) { 426 error = EOVERFLOW; 427 break; 428 } 429 offset += foffset; 430 break; 431 case L_XTND: 432 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 433 error = EOVERFLOW; 434 break; 435 } 436 offset += shmfd->shm_size; 437 break; 438 case L_SET: 439 break; 440 default: 441 error = EINVAL; 442 } 443 if (error == 0) { 444 if (offset < 0 || offset > shmfd->shm_size) 445 error = EINVAL; 446 else 447 td->td_uretoff.tdu_off = offset; 448 } 449 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 450 return (error); 451 } 452 453 static int 454 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 455 int flags, struct thread *td) 456 { 457 struct shmfd *shmfd; 458 void *rl_cookie; 459 int error; 460 461 shmfd = fp->f_data; 462 #ifdef MAC 463 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 464 if (error) 465 return (error); 466 #endif 467 foffset_lock_uio(fp, uio, flags); 468 rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset, 469 uio->uio_offset + uio->uio_resid); 470 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 471 shm_rangelock_unlock(shmfd, rl_cookie); 472 foffset_unlock_uio(fp, uio, flags); 473 return (error); 474 } 475 476 static int 477 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 478 int flags, struct thread *td) 479 { 480 struct shmfd *shmfd; 481 void *rl_cookie; 482 int error; 483 off_t size; 484 485 shmfd = fp->f_data; 486 #ifdef MAC 487 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 488 if (error) 489 return (error); 490 #endif 491 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 492 return (EINVAL); 493 foffset_lock_uio(fp, uio, flags); 494 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 495 /* 496 * Overflow is only an error if we're supposed to expand on 497 * write. Otherwise, we'll just truncate the write to the 498 * size of the file, which can only grow up to OFF_MAX. 499 */ 500 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 501 foffset_unlock_uio(fp, uio, flags); 502 return (EFBIG); 503 } 504 505 size = shmfd->shm_size; 506 } else { 507 size = uio->uio_offset + uio->uio_resid; 508 } 509 if ((flags & FOF_OFFSET) == 0) 510 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 511 else 512 rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, size); 513 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 514 error = EPERM; 515 } else { 516 error = 0; 517 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 518 size > shmfd->shm_size) { 519 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 520 } 521 if (error == 0) 522 error = uiomove_object(shmfd->shm_object, 523 shmfd->shm_size, uio); 524 } 525 shm_rangelock_unlock(shmfd, rl_cookie); 526 foffset_unlock_uio(fp, uio, flags); 527 return (error); 528 } 529 530 static int 531 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 532 struct thread *td) 533 { 534 struct shmfd *shmfd; 535 #ifdef MAC 536 int error; 537 #endif 538 539 shmfd = fp->f_data; 540 #ifdef MAC 541 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 542 if (error) 543 return (error); 544 #endif 545 return (shm_dotruncate(shmfd, length)); 546 } 547 548 int 549 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 550 struct thread *td) 551 { 552 struct shmfd *shmfd; 553 struct shm_largepage_conf *conf; 554 void *rl_cookie; 555 556 shmfd = fp->f_data; 557 switch (com) { 558 case FIONBIO: 559 case FIOASYNC: 560 /* 561 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 562 * just like it would on an unlinked regular file 563 */ 564 return (0); 565 case FIOSSHMLPGCNF: 566 if (!shm_largepage(shmfd)) 567 return (ENOTTY); 568 conf = data; 569 if (shmfd->shm_lp_psind != 0 && 570 conf->psind != shmfd->shm_lp_psind) 571 return (EINVAL); 572 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 573 pagesizes[conf->psind] == 0) 574 return (EINVAL); 575 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 576 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 577 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 578 return (EINVAL); 579 580 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 581 shmfd->shm_lp_psind = conf->psind; 582 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 583 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 584 shm_rangelock_unlock(shmfd, rl_cookie); 585 return (0); 586 case FIOGSHMLPGCNF: 587 if (!shm_largepage(shmfd)) 588 return (ENOTTY); 589 conf = data; 590 rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX); 591 conf->psind = shmfd->shm_lp_psind; 592 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 593 shm_rangelock_unlock(shmfd, rl_cookie); 594 return (0); 595 default: 596 return (ENOTTY); 597 } 598 } 599 600 static int 601 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred) 602 { 603 struct shmfd *shmfd; 604 #ifdef MAC 605 int error; 606 #endif 607 608 shmfd = fp->f_data; 609 610 #ifdef MAC 611 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 612 if (error) 613 return (error); 614 #endif 615 616 /* 617 * Attempt to return sanish values for fstat() on a memory file 618 * descriptor. 619 */ 620 bzero(sb, sizeof(*sb)); 621 sb->st_blksize = PAGE_SIZE; 622 sb->st_size = shmfd->shm_size; 623 mtx_lock(&shm_timestamp_lock); 624 sb->st_atim = shmfd->shm_atime; 625 sb->st_ctim = shmfd->shm_ctime; 626 sb->st_mtim = shmfd->shm_mtime; 627 sb->st_birthtim = shmfd->shm_birthtime; 628 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 629 sb->st_uid = shmfd->shm_uid; 630 sb->st_gid = shmfd->shm_gid; 631 mtx_unlock(&shm_timestamp_lock); 632 sb->st_dev = shm_dev_ino; 633 sb->st_ino = shmfd->shm_ino; 634 sb->st_nlink = shmfd->shm_object->ref_count; 635 if (shm_largepage(shmfd)) { 636 sb->st_blocks = shmfd->shm_object->size / 637 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 638 } else { 639 sb->st_blocks = shmfd->shm_pages; 640 } 641 642 return (0); 643 } 644 645 static int 646 shm_close(struct file *fp, struct thread *td) 647 { 648 struct shmfd *shmfd; 649 650 shmfd = fp->f_data; 651 fp->f_data = NULL; 652 shm_drop(shmfd); 653 654 return (0); 655 } 656 657 static int 658 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 659 int error; 660 char *path; 661 const char *pr_path; 662 size_t pr_pathlen; 663 664 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 665 pr_path = td->td_ucred->cr_prison->pr_path; 666 667 /* Construct a full pathname for jailed callers. */ 668 pr_pathlen = strcmp(pr_path, "/") == 669 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 670 error = copyinstr(userpath_in, path + pr_pathlen, 671 MAXPATHLEN - pr_pathlen, NULL); 672 if (error != 0) 673 goto out; 674 675 #ifdef KTRACE 676 if (KTRPOINT(curthread, KTR_NAMEI)) 677 ktrnamei(path); 678 #endif 679 680 /* Require paths to start with a '/' character. */ 681 if (path[pr_pathlen] != '/') { 682 error = EINVAL; 683 goto out; 684 } 685 686 *path_out = path; 687 688 out: 689 if (error != 0) 690 free(path, M_SHMFD); 691 692 return (error); 693 } 694 695 static int 696 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base, 697 int end) 698 { 699 vm_page_t m; 700 int rv; 701 702 VM_OBJECT_ASSERT_WLOCKED(object); 703 KASSERT(base >= 0, ("%s: base %d", __func__, base)); 704 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base, 705 end)); 706 707 retry: 708 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 709 if (m != NULL) { 710 MPASS(vm_page_all_valid(m)); 711 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 712 m = vm_page_alloc(object, idx, 713 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 714 if (m == NULL) 715 goto retry; 716 vm_object_pip_add(object, 1); 717 VM_OBJECT_WUNLOCK(object); 718 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL); 719 VM_OBJECT_WLOCK(object); 720 vm_object_pip_wakeup(object); 721 if (rv == VM_PAGER_OK) { 722 /* 723 * Since the page was not resident, and therefore not 724 * recently accessed, immediately enqueue it for 725 * asynchronous laundering. The current operation is 726 * not regarded as an access. 727 */ 728 vm_page_launder(m); 729 } else { 730 vm_page_free(m); 731 VM_OBJECT_WUNLOCK(object); 732 return (EIO); 733 } 734 } 735 if (m != NULL) { 736 pmap_zero_page_area(m, base, end - base); 737 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid", 738 __func__, m)); 739 vm_page_set_dirty(m); 740 vm_page_xunbusy(m); 741 } 742 743 return (0); 744 } 745 746 static int 747 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 748 { 749 vm_object_t object; 750 vm_pindex_t nobjsize; 751 vm_ooffset_t delta; 752 int base, error; 753 754 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 755 object = shmfd->shm_object; 756 VM_OBJECT_ASSERT_WLOCKED(object); 757 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 758 if (length == shmfd->shm_size) 759 return (0); 760 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 761 762 /* Are we shrinking? If so, trim the end. */ 763 if (length < shmfd->shm_size) { 764 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 765 return (EPERM); 766 767 /* 768 * Disallow any requests to shrink the size if this 769 * object is mapped into the kernel. 770 */ 771 if (shmfd->shm_kmappings > 0) 772 return (EBUSY); 773 774 /* 775 * Zero the truncated part of the last page. 776 */ 777 base = length & PAGE_MASK; 778 if (base != 0) { 779 error = shm_partial_page_invalidate(object, 780 OFF_TO_IDX(length), base, PAGE_SIZE); 781 if (error) 782 return (error); 783 } 784 delta = IDX_TO_OFF(object->size - nobjsize); 785 786 if (nobjsize < object->size) 787 vm_object_page_remove(object, nobjsize, object->size, 788 0); 789 790 /* Free the swap accounted for shm */ 791 swap_release_by_cred(delta, object->cred); 792 object->charge -= delta; 793 } else { 794 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 795 return (EPERM); 796 797 /* Try to reserve additional swap space. */ 798 delta = IDX_TO_OFF(nobjsize - object->size); 799 if (!swap_reserve_by_cred(delta, object->cred)) 800 return (ENOMEM); 801 object->charge += delta; 802 } 803 shmfd->shm_size = length; 804 mtx_lock(&shm_timestamp_lock); 805 vfs_timestamp(&shmfd->shm_ctime); 806 shmfd->shm_mtime = shmfd->shm_ctime; 807 mtx_unlock(&shm_timestamp_lock); 808 object->size = nobjsize; 809 return (0); 810 } 811 812 static int 813 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 814 { 815 vm_object_t object; 816 vm_page_t m; 817 vm_pindex_t newobjsz; 818 vm_pindex_t oldobjsz __unused; 819 int aflags, error, i, psind, try; 820 821 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 822 object = shmfd->shm_object; 823 VM_OBJECT_ASSERT_WLOCKED(object); 824 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 825 826 oldobjsz = object->size; 827 newobjsz = OFF_TO_IDX(length); 828 if (length == shmfd->shm_size) 829 return (0); 830 psind = shmfd->shm_lp_psind; 831 if (psind == 0 && length != 0) 832 return (EINVAL); 833 if ((length & (pagesizes[psind] - 1)) != 0) 834 return (EINVAL); 835 836 if (length < shmfd->shm_size) { 837 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 838 return (EPERM); 839 if (shmfd->shm_kmappings > 0) 840 return (EBUSY); 841 return (ENOTSUP); /* Pages are unmanaged. */ 842 #if 0 843 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 844 object->size = newobjsz; 845 shmfd->shm_size = length; 846 return (0); 847 #endif 848 } 849 850 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 851 return (EPERM); 852 853 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 854 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 855 aflags |= VM_ALLOC_WAITFAIL; 856 try = 0; 857 858 /* 859 * Extend shmfd and object, keeping all already fully 860 * allocated large pages intact even on error, because dropped 861 * object lock might allowed mapping of them. 862 */ 863 while (object->size < newobjsz) { 864 m = vm_page_alloc_contig(object, object->size, aflags, 865 pagesizes[psind] / PAGE_SIZE, 0, ~0, 866 pagesizes[psind], 0, 867 VM_MEMATTR_DEFAULT); 868 if (m == NULL) { 869 VM_OBJECT_WUNLOCK(object); 870 if (shmfd->shm_lp_alloc_policy == 871 SHM_LARGEPAGE_ALLOC_NOWAIT || 872 (shmfd->shm_lp_alloc_policy == 873 SHM_LARGEPAGE_ALLOC_DEFAULT && 874 try >= largepage_reclaim_tries)) { 875 VM_OBJECT_WLOCK(object); 876 return (ENOMEM); 877 } 878 error = vm_page_reclaim_contig(aflags, 879 pagesizes[psind] / PAGE_SIZE, 0, ~0, 880 pagesizes[psind], 0) ? 0 : 881 vm_wait_intr(object); 882 if (error != 0) { 883 VM_OBJECT_WLOCK(object); 884 return (error); 885 } 886 try++; 887 VM_OBJECT_WLOCK(object); 888 continue; 889 } 890 try = 0; 891 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 892 if ((m[i].flags & PG_ZERO) == 0) 893 pmap_zero_page(&m[i]); 894 vm_page_valid(&m[i]); 895 vm_page_xunbusy(&m[i]); 896 } 897 object->size += OFF_TO_IDX(pagesizes[psind]); 898 shmfd->shm_size += pagesizes[psind]; 899 atomic_add_long(&count_largepages[psind], 1); 900 vm_wire_add(atop(pagesizes[psind])); 901 } 902 return (0); 903 } 904 905 static int 906 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 907 { 908 int error; 909 910 VM_OBJECT_WLOCK(shmfd->shm_object); 911 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 912 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 913 rl_cookie); 914 VM_OBJECT_WUNLOCK(shmfd->shm_object); 915 return (error); 916 } 917 918 int 919 shm_dotruncate(struct shmfd *shmfd, off_t length) 920 { 921 void *rl_cookie; 922 int error; 923 924 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 925 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 926 shm_rangelock_unlock(shmfd, rl_cookie); 927 return (error); 928 } 929 930 /* 931 * shmfd object management including creation and reference counting 932 * routines. 933 */ 934 struct shmfd * 935 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 936 { 937 struct shmfd *shmfd; 938 vm_object_t obj; 939 940 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 941 shmfd->shm_size = 0; 942 shmfd->shm_uid = ucred->cr_uid; 943 shmfd->shm_gid = ucred->cr_gid; 944 shmfd->shm_mode = mode; 945 if (largepage) { 946 shmfd->shm_object = phys_pager_allocate(NULL, 947 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 948 VM_PROT_DEFAULT, 0, ucred); 949 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 950 } else { 951 obj = vm_pager_allocate(shmfd_pager_type, NULL, 952 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 953 VM_OBJECT_WLOCK(obj); 954 obj->un_pager.swp.swp_priv = shmfd; 955 VM_OBJECT_WUNLOCK(obj); 956 shmfd->shm_object = obj; 957 } 958 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 959 vfs_timestamp(&shmfd->shm_birthtime); 960 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 961 shmfd->shm_birthtime; 962 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 963 refcount_init(&shmfd->shm_refs, 1); 964 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 965 rangelock_init(&shmfd->shm_rl); 966 #ifdef MAC 967 mac_posixshm_init(shmfd); 968 mac_posixshm_create(ucred, shmfd); 969 #endif 970 971 return (shmfd); 972 } 973 974 struct shmfd * 975 shm_hold(struct shmfd *shmfd) 976 { 977 978 refcount_acquire(&shmfd->shm_refs); 979 return (shmfd); 980 } 981 982 void 983 shm_drop(struct shmfd *shmfd) 984 { 985 vm_object_t obj; 986 987 if (refcount_release(&shmfd->shm_refs)) { 988 #ifdef MAC 989 mac_posixshm_destroy(shmfd); 990 #endif 991 rangelock_destroy(&shmfd->shm_rl); 992 mtx_destroy(&shmfd->shm_mtx); 993 obj = shmfd->shm_object; 994 if (!shm_largepage(shmfd)) { 995 VM_OBJECT_WLOCK(obj); 996 obj->un_pager.swp.swp_priv = NULL; 997 VM_OBJECT_WUNLOCK(obj); 998 } 999 vm_object_deallocate(obj); 1000 free(shmfd, M_SHMFD); 1001 } 1002 } 1003 1004 /* 1005 * Determine if the credentials have sufficient permissions for a 1006 * specified combination of FREAD and FWRITE. 1007 */ 1008 int 1009 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 1010 { 1011 accmode_t accmode; 1012 int error; 1013 1014 accmode = 0; 1015 if (flags & FREAD) 1016 accmode |= VREAD; 1017 if (flags & FWRITE) 1018 accmode |= VWRITE; 1019 mtx_lock(&shm_timestamp_lock); 1020 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1021 accmode, ucred); 1022 mtx_unlock(&shm_timestamp_lock); 1023 return (error); 1024 } 1025 1026 static void 1027 shm_init(void *arg) 1028 { 1029 char name[32]; 1030 int i; 1031 1032 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 1033 sx_init(&shm_dict_lock, "shm dictionary"); 1034 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 1035 new_unrhdr64(&shm_ino_unr, 1); 1036 shm_dev_ino = devfs_alloc_cdp_inode(); 1037 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 1038 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops, 1039 OBJT_SWAP); 1040 MPASS(shmfd_pager_type != -1); 1041 1042 for (i = 1; i < MAXPAGESIZES; i++) { 1043 if (pagesizes[i] == 0) 1044 break; 1045 #define M (1024 * 1024) 1046 #define G (1024 * M) 1047 if (pagesizes[i] >= G) 1048 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 1049 else if (pagesizes[i] >= M) 1050 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 1051 else 1052 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 1053 #undef G 1054 #undef M 1055 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 1056 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 1057 "number of non-transient largepages allocated"); 1058 } 1059 } 1060 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 1061 1062 /* 1063 * Remove all shared memory objects that belong to a prison. 1064 */ 1065 void 1066 shm_remove_prison(struct prison *pr) 1067 { 1068 struct shm_mapping *shmm, *tshmm; 1069 u_long i; 1070 1071 sx_xlock(&shm_dict_lock); 1072 for (i = 0; i < shm_hash + 1; i++) { 1073 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) { 1074 if (shmm->sm_shmfd->shm_object->cred && 1075 shmm->sm_shmfd->shm_object->cred->cr_prison == pr) 1076 shm_doremove(shmm); 1077 } 1078 } 1079 sx_xunlock(&shm_dict_lock); 1080 } 1081 1082 /* 1083 * Dictionary management. We maintain an in-kernel dictionary to map 1084 * paths to shmfd objects. We use the FNV hash on the path to store 1085 * the mappings in a hash table. 1086 */ 1087 static struct shmfd * 1088 shm_lookup(char *path, Fnv32_t fnv) 1089 { 1090 struct shm_mapping *map; 1091 1092 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1093 if (map->sm_fnv != fnv) 1094 continue; 1095 if (strcmp(map->sm_path, path) == 0) 1096 return (map->sm_shmfd); 1097 } 1098 1099 return (NULL); 1100 } 1101 1102 static void 1103 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 1104 { 1105 struct shm_mapping *map; 1106 1107 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 1108 map->sm_path = path; 1109 map->sm_fnv = fnv; 1110 map->sm_shmfd = shm_hold(shmfd); 1111 shmfd->shm_path = path; 1112 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 1113 } 1114 1115 static int 1116 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1117 { 1118 struct shm_mapping *map; 1119 int error; 1120 1121 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1122 if (map->sm_fnv != fnv) 1123 continue; 1124 if (strcmp(map->sm_path, path) == 0) { 1125 #ifdef MAC 1126 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1127 if (error) 1128 return (error); 1129 #endif 1130 error = shm_access(map->sm_shmfd, ucred, 1131 FREAD | FWRITE); 1132 if (error) 1133 return (error); 1134 shm_doremove(map); 1135 return (0); 1136 } 1137 } 1138 1139 return (ENOENT); 1140 } 1141 1142 static void 1143 shm_doremove(struct shm_mapping *map) 1144 { 1145 map->sm_shmfd->shm_path = NULL; 1146 LIST_REMOVE(map, sm_link); 1147 shm_drop(map->sm_shmfd); 1148 free(map->sm_path, M_SHMFD); 1149 free(map, M_SHMFD); 1150 } 1151 1152 int 1153 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1154 int shmflags, struct filecaps *fcaps, const char *name __unused) 1155 { 1156 struct pwddesc *pdp; 1157 struct shmfd *shmfd; 1158 struct file *fp; 1159 char *path; 1160 void *rl_cookie; 1161 Fnv32_t fnv; 1162 mode_t cmode; 1163 int error, fd, initial_seals; 1164 bool largepage; 1165 1166 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1167 SHM_LARGEPAGE)) != 0) 1168 return (EINVAL); 1169 1170 initial_seals = F_SEAL_SEAL; 1171 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1172 initial_seals &= ~F_SEAL_SEAL; 1173 1174 #ifdef CAPABILITY_MODE 1175 /* 1176 * shm_open(2) is only allowed for anonymous objects. 1177 */ 1178 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1179 return (ECAPMODE); 1180 #endif 1181 1182 AUDIT_ARG_FFLAGS(flags); 1183 AUDIT_ARG_MODE(mode); 1184 1185 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1186 return (EINVAL); 1187 1188 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1189 return (EINVAL); 1190 1191 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1192 if (largepage && !PMAP_HAS_LARGEPAGES) 1193 return (ENOTTY); 1194 1195 /* 1196 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1197 * If the decision is made later to allow additional seals, care must be 1198 * taken below to ensure that the seals are properly set if the shmfd 1199 * already existed -- this currently assumes that only F_SEAL_SEAL can 1200 * be set and doesn't take further precautions to ensure the validity of 1201 * the seals being added with respect to current mappings. 1202 */ 1203 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1204 return (EINVAL); 1205 1206 pdp = td->td_proc->p_pd; 1207 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1208 1209 /* 1210 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1211 * by POSIX. We allow it to be unset here so that an in-kernel 1212 * interface may be written as a thin layer around shm, optionally not 1213 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1214 * in sys_shm_open() to keep this implementation compliant. 1215 */ 1216 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1217 if (error) 1218 return (error); 1219 1220 /* A SHM_ANON path pointer creates an anonymous object. */ 1221 if (userpath == SHM_ANON) { 1222 /* A read-only anonymous object is pointless. */ 1223 if ((flags & O_ACCMODE) == O_RDONLY) { 1224 fdclose(td, fp, fd); 1225 fdrop(fp, td); 1226 return (EINVAL); 1227 } 1228 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1229 shmfd->shm_seals = initial_seals; 1230 shmfd->shm_flags = shmflags; 1231 } else { 1232 error = shm_copyin_path(td, userpath, &path); 1233 if (error != 0) { 1234 fdclose(td, fp, fd); 1235 fdrop(fp, td); 1236 return (error); 1237 } 1238 1239 AUDIT_ARG_UPATH1_CANON(path); 1240 fnv = fnv_32_str(path, FNV1_32_INIT); 1241 sx_xlock(&shm_dict_lock); 1242 shmfd = shm_lookup(path, fnv); 1243 if (shmfd == NULL) { 1244 /* Object does not yet exist, create it if requested. */ 1245 if (flags & O_CREAT) { 1246 #ifdef MAC 1247 error = mac_posixshm_check_create(td->td_ucred, 1248 path); 1249 if (error == 0) { 1250 #endif 1251 shmfd = shm_alloc(td->td_ucred, cmode, 1252 largepage); 1253 shmfd->shm_seals = initial_seals; 1254 shmfd->shm_flags = shmflags; 1255 shm_insert(path, fnv, shmfd); 1256 #ifdef MAC 1257 } 1258 #endif 1259 } else { 1260 free(path, M_SHMFD); 1261 error = ENOENT; 1262 } 1263 } else { 1264 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 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 shm_rangelock_unlock(shmfd, rl_cookie); 1337 } 1338 sx_xunlock(&shm_dict_lock); 1339 1340 if (error) { 1341 fdclose(td, fp, fd); 1342 fdrop(fp, td); 1343 return (error); 1344 } 1345 } 1346 1347 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1348 1349 td->td_retval[0] = fd; 1350 fdrop(fp, td); 1351 1352 return (0); 1353 } 1354 1355 /* System calls. */ 1356 #ifdef COMPAT_FREEBSD12 1357 int 1358 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1359 { 1360 1361 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1362 uap->mode, NULL)); 1363 } 1364 #endif 1365 1366 int 1367 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1368 { 1369 char *path; 1370 Fnv32_t fnv; 1371 int error; 1372 1373 error = shm_copyin_path(td, uap->path, &path); 1374 if (error != 0) 1375 return (error); 1376 1377 AUDIT_ARG_UPATH1_CANON(path); 1378 fnv = fnv_32_str(path, FNV1_32_INIT); 1379 sx_xlock(&shm_dict_lock); 1380 error = shm_remove(path, fnv, td->td_ucred); 1381 sx_xunlock(&shm_dict_lock); 1382 free(path, M_SHMFD); 1383 1384 return (error); 1385 } 1386 1387 int 1388 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1389 { 1390 char *path_from = NULL, *path_to = NULL; 1391 Fnv32_t fnv_from, fnv_to; 1392 struct shmfd *fd_from; 1393 struct shmfd *fd_to; 1394 int error; 1395 int flags; 1396 1397 flags = uap->flags; 1398 AUDIT_ARG_FFLAGS(flags); 1399 1400 /* 1401 * Make sure the user passed only valid flags. 1402 * If you add a new flag, please add a new term here. 1403 */ 1404 if ((flags & ~( 1405 SHM_RENAME_NOREPLACE | 1406 SHM_RENAME_EXCHANGE 1407 )) != 0) { 1408 error = EINVAL; 1409 goto out; 1410 } 1411 1412 /* 1413 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1414 * force the user to choose one or the other. 1415 */ 1416 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1417 (flags & SHM_RENAME_EXCHANGE) != 0) { 1418 error = EINVAL; 1419 goto out; 1420 } 1421 1422 /* Renaming to or from anonymous makes no sense */ 1423 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1424 error = EINVAL; 1425 goto out; 1426 } 1427 1428 error = shm_copyin_path(td, uap->path_from, &path_from); 1429 if (error != 0) 1430 goto out; 1431 1432 error = shm_copyin_path(td, uap->path_to, &path_to); 1433 if (error != 0) 1434 goto out; 1435 1436 AUDIT_ARG_UPATH1_CANON(path_from); 1437 AUDIT_ARG_UPATH2_CANON(path_to); 1438 1439 /* Rename with from/to equal is a no-op */ 1440 if (strcmp(path_from, path_to) == 0) 1441 goto out; 1442 1443 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1444 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1445 1446 sx_xlock(&shm_dict_lock); 1447 1448 fd_from = shm_lookup(path_from, fnv_from); 1449 if (fd_from == NULL) { 1450 error = ENOENT; 1451 goto out_locked; 1452 } 1453 1454 fd_to = shm_lookup(path_to, fnv_to); 1455 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1456 error = EEXIST; 1457 goto out_locked; 1458 } 1459 1460 /* 1461 * Unconditionally prevents shm_remove from invalidating the 'from' 1462 * shm's state. 1463 */ 1464 shm_hold(fd_from); 1465 error = shm_remove(path_from, fnv_from, td->td_ucred); 1466 1467 /* 1468 * One of my assumptions failed if ENOENT (e.g. locking didn't 1469 * protect us) 1470 */ 1471 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1472 path_from)); 1473 if (error != 0) { 1474 shm_drop(fd_from); 1475 goto out_locked; 1476 } 1477 1478 /* 1479 * If we are exchanging, we need to ensure the shm_remove below 1480 * doesn't invalidate the dest shm's state. 1481 */ 1482 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1483 shm_hold(fd_to); 1484 1485 /* 1486 * NOTE: if path_to is not already in the hash, c'est la vie; 1487 * it simply means we have nothing already at path_to to unlink. 1488 * That is the ENOENT case. 1489 * 1490 * If we somehow don't have access to unlink this guy, but 1491 * did for the shm at path_from, then relink the shm to path_from 1492 * and abort with EACCES. 1493 * 1494 * All other errors: that is weird; let's relink and abort the 1495 * operation. 1496 */ 1497 error = shm_remove(path_to, fnv_to, td->td_ucred); 1498 if (error != 0 && error != ENOENT) { 1499 shm_insert(path_from, fnv_from, fd_from); 1500 shm_drop(fd_from); 1501 /* Don't free path_from now, since the hash references it */ 1502 path_from = NULL; 1503 goto out_locked; 1504 } 1505 1506 error = 0; 1507 1508 shm_insert(path_to, fnv_to, fd_from); 1509 1510 /* Don't free path_to now, since the hash references it */ 1511 path_to = NULL; 1512 1513 /* We kept a ref when we removed, and incremented again in insert */ 1514 shm_drop(fd_from); 1515 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1516 fd_from->shm_refs)); 1517 1518 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1519 shm_insert(path_from, fnv_from, fd_to); 1520 path_from = NULL; 1521 shm_drop(fd_to); 1522 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1523 fd_to->shm_refs)); 1524 } 1525 1526 out_locked: 1527 sx_xunlock(&shm_dict_lock); 1528 1529 out: 1530 free(path_from, M_SHMFD); 1531 free(path_to, M_SHMFD); 1532 return (error); 1533 } 1534 1535 static int 1536 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1537 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1538 vm_ooffset_t foff, struct thread *td) 1539 { 1540 struct vmspace *vms; 1541 vm_map_entry_t next_entry, prev_entry; 1542 vm_offset_t align, mask, maxaddr; 1543 int docow, error, rv, try; 1544 bool curmap; 1545 1546 if (shmfd->shm_lp_psind == 0) 1547 return (EINVAL); 1548 1549 /* MAP_PRIVATE is disabled */ 1550 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1551 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0) 1552 return (EINVAL); 1553 1554 vms = td->td_proc->p_vmspace; 1555 curmap = map == &vms->vm_map; 1556 if (curmap) { 1557 error = kern_mmap_racct_check(td, map, size); 1558 if (error != 0) 1559 return (error); 1560 } 1561 1562 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1563 docow |= MAP_INHERIT_SHARE; 1564 if ((flags & MAP_NOCORE) != 0) 1565 docow |= MAP_DISABLE_COREDUMP; 1566 1567 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1568 if ((foff & mask) != 0) 1569 return (EINVAL); 1570 maxaddr = vm_map_max(map); 1571 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1572 maxaddr = MAP_32BIT_MAX_ADDR; 1573 if (size == 0 || (size & mask) != 0 || 1574 (*addr != 0 && ((*addr & mask) != 0 || 1575 *addr + size < *addr || *addr + size > maxaddr))) 1576 return (EINVAL); 1577 1578 align = flags & MAP_ALIGNMENT_MASK; 1579 if (align == 0) { 1580 align = pagesizes[shmfd->shm_lp_psind]; 1581 } else if (align == MAP_ALIGNED_SUPER) { 1582 if (shmfd->shm_lp_psind != 1) 1583 return (EINVAL); 1584 align = pagesizes[1]; 1585 } else { 1586 align >>= MAP_ALIGNMENT_SHIFT; 1587 align = 1ULL << align; 1588 /* Also handles overflow. */ 1589 if (align < pagesizes[shmfd->shm_lp_psind]) 1590 return (EINVAL); 1591 } 1592 1593 vm_map_lock(map); 1594 if ((flags & MAP_FIXED) == 0) { 1595 try = 1; 1596 if (curmap && (*addr == 0 || 1597 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1598 *addr < round_page((vm_offset_t)vms->vm_daddr + 1599 lim_max(td, RLIMIT_DATA))))) { 1600 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1601 lim_max(td, RLIMIT_DATA), 1602 pagesizes[shmfd->shm_lp_psind]); 1603 } 1604 again: 1605 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1606 if (rv != KERN_SUCCESS) { 1607 if (try == 1) { 1608 try = 2; 1609 *addr = vm_map_min(map); 1610 if ((*addr & mask) != 0) 1611 *addr = (*addr + mask) & mask; 1612 goto again; 1613 } 1614 goto fail1; 1615 } 1616 } else if ((flags & MAP_EXCL) == 0) { 1617 rv = vm_map_delete(map, *addr, *addr + size); 1618 if (rv != KERN_SUCCESS) 1619 goto fail1; 1620 } else { 1621 error = ENOSPC; 1622 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1623 goto fail; 1624 next_entry = vm_map_entry_succ(prev_entry); 1625 if (next_entry->start < *addr + size) 1626 goto fail; 1627 } 1628 1629 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1630 prot, max_prot, docow); 1631 fail1: 1632 error = vm_mmap_to_errno(rv); 1633 fail: 1634 vm_map_unlock(map); 1635 return (error); 1636 } 1637 1638 static int 1639 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1640 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1641 vm_ooffset_t foff, struct thread *td) 1642 { 1643 struct shmfd *shmfd; 1644 vm_prot_t maxprot; 1645 int error; 1646 bool writecnt; 1647 void *rl_cookie; 1648 1649 shmfd = fp->f_data; 1650 maxprot = VM_PROT_NONE; 1651 1652 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize); 1653 /* FREAD should always be set. */ 1654 if ((fp->f_flag & FREAD) != 0) 1655 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1656 1657 /* 1658 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1659 * mapping with a write seal applied. Private mappings are always 1660 * writeable. 1661 */ 1662 if ((flags & MAP_SHARED) == 0) { 1663 cap_maxprot |= VM_PROT_WRITE; 1664 maxprot |= VM_PROT_WRITE; 1665 writecnt = false; 1666 } else { 1667 if ((fp->f_flag & FWRITE) != 0 && 1668 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1669 maxprot |= VM_PROT_WRITE; 1670 1671 /* 1672 * Any mappings from a writable descriptor may be upgraded to 1673 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1674 * applied between the open and subsequent mmap(2). We want to 1675 * reject application of a write seal as long as any such 1676 * mapping exists so that the seal cannot be trivially bypassed. 1677 */ 1678 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1679 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1680 error = EACCES; 1681 goto out; 1682 } 1683 } 1684 maxprot &= cap_maxprot; 1685 1686 /* See comment in vn_mmap(). */ 1687 if ( 1688 #ifdef _LP64 1689 objsize > OFF_MAX || 1690 #endif 1691 foff > OFF_MAX - objsize) { 1692 error = EINVAL; 1693 goto out; 1694 } 1695 1696 #ifdef MAC 1697 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1698 if (error != 0) 1699 goto out; 1700 #endif 1701 1702 mtx_lock(&shm_timestamp_lock); 1703 vfs_timestamp(&shmfd->shm_atime); 1704 mtx_unlock(&shm_timestamp_lock); 1705 vm_object_reference(shmfd->shm_object); 1706 1707 if (shm_largepage(shmfd)) { 1708 writecnt = false; 1709 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1710 maxprot, flags, foff, td); 1711 } else { 1712 if (writecnt) { 1713 vm_pager_update_writecount(shmfd->shm_object, 0, 1714 objsize); 1715 } 1716 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1717 shmfd->shm_object, foff, writecnt, td); 1718 } 1719 if (error != 0) { 1720 if (writecnt) 1721 vm_pager_release_writecount(shmfd->shm_object, 0, 1722 objsize); 1723 vm_object_deallocate(shmfd->shm_object); 1724 } 1725 out: 1726 shm_rangelock_unlock(shmfd, rl_cookie); 1727 return (error); 1728 } 1729 1730 static int 1731 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1732 struct thread *td) 1733 { 1734 struct shmfd *shmfd; 1735 int error; 1736 1737 error = 0; 1738 shmfd = fp->f_data; 1739 mtx_lock(&shm_timestamp_lock); 1740 /* 1741 * SUSv4 says that x bits of permission need not be affected. 1742 * Be consistent with our shm_open there. 1743 */ 1744 #ifdef MAC 1745 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1746 if (error != 0) 1747 goto out; 1748 #endif 1749 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1750 VADMIN, active_cred); 1751 if (error != 0) 1752 goto out; 1753 shmfd->shm_mode = mode & ACCESSPERMS; 1754 out: 1755 mtx_unlock(&shm_timestamp_lock); 1756 return (error); 1757 } 1758 1759 static int 1760 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1761 struct thread *td) 1762 { 1763 struct shmfd *shmfd; 1764 int error; 1765 1766 error = 0; 1767 shmfd = fp->f_data; 1768 mtx_lock(&shm_timestamp_lock); 1769 #ifdef MAC 1770 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1771 if (error != 0) 1772 goto out; 1773 #endif 1774 if (uid == (uid_t)-1) 1775 uid = shmfd->shm_uid; 1776 if (gid == (gid_t)-1) 1777 gid = shmfd->shm_gid; 1778 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1779 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1780 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1781 goto out; 1782 shmfd->shm_uid = uid; 1783 shmfd->shm_gid = gid; 1784 out: 1785 mtx_unlock(&shm_timestamp_lock); 1786 return (error); 1787 } 1788 1789 /* 1790 * Helper routines to allow the backing object of a shared memory file 1791 * descriptor to be mapped in the kernel. 1792 */ 1793 int 1794 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1795 { 1796 struct shmfd *shmfd; 1797 vm_offset_t kva, ofs; 1798 vm_object_t obj; 1799 int rv; 1800 1801 if (fp->f_type != DTYPE_SHM) 1802 return (EINVAL); 1803 shmfd = fp->f_data; 1804 obj = shmfd->shm_object; 1805 VM_OBJECT_WLOCK(obj); 1806 /* 1807 * XXXRW: This validation is probably insufficient, and subject to 1808 * sign errors. It should be fixed. 1809 */ 1810 if (offset >= shmfd->shm_size || 1811 offset + size > round_page(shmfd->shm_size)) { 1812 VM_OBJECT_WUNLOCK(obj); 1813 return (EINVAL); 1814 } 1815 1816 shmfd->shm_kmappings++; 1817 vm_object_reference_locked(obj); 1818 VM_OBJECT_WUNLOCK(obj); 1819 1820 /* Map the object into the kernel_map and wire it. */ 1821 kva = vm_map_min(kernel_map); 1822 ofs = offset & PAGE_MASK; 1823 offset = trunc_page(offset); 1824 size = round_page(size + ofs); 1825 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1826 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1827 VM_PROT_READ | VM_PROT_WRITE, 0); 1828 if (rv == KERN_SUCCESS) { 1829 rv = vm_map_wire(kernel_map, kva, kva + size, 1830 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1831 if (rv == KERN_SUCCESS) { 1832 *memp = (void *)(kva + ofs); 1833 return (0); 1834 } 1835 vm_map_remove(kernel_map, kva, kva + size); 1836 } else 1837 vm_object_deallocate(obj); 1838 1839 /* On failure, drop our mapping reference. */ 1840 VM_OBJECT_WLOCK(obj); 1841 shmfd->shm_kmappings--; 1842 VM_OBJECT_WUNLOCK(obj); 1843 1844 return (vm_mmap_to_errno(rv)); 1845 } 1846 1847 /* 1848 * We require the caller to unmap the entire entry. This allows us to 1849 * safely decrement shm_kmappings when a mapping is removed. 1850 */ 1851 int 1852 shm_unmap(struct file *fp, void *mem, size_t size) 1853 { 1854 struct shmfd *shmfd; 1855 vm_map_entry_t entry; 1856 vm_offset_t kva, ofs; 1857 vm_object_t obj; 1858 vm_pindex_t pindex; 1859 vm_prot_t prot; 1860 boolean_t wired; 1861 vm_map_t map; 1862 int rv; 1863 1864 if (fp->f_type != DTYPE_SHM) 1865 return (EINVAL); 1866 shmfd = fp->f_data; 1867 kva = (vm_offset_t)mem; 1868 ofs = kva & PAGE_MASK; 1869 kva = trunc_page(kva); 1870 size = round_page(size + ofs); 1871 map = kernel_map; 1872 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1873 &obj, &pindex, &prot, &wired); 1874 if (rv != KERN_SUCCESS) 1875 return (EINVAL); 1876 if (entry->start != kva || entry->end != kva + size) { 1877 vm_map_lookup_done(map, entry); 1878 return (EINVAL); 1879 } 1880 vm_map_lookup_done(map, entry); 1881 if (obj != shmfd->shm_object) 1882 return (EINVAL); 1883 vm_map_remove(map, kva, kva + size); 1884 VM_OBJECT_WLOCK(obj); 1885 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1886 shmfd->shm_kmappings--; 1887 VM_OBJECT_WUNLOCK(obj); 1888 return (0); 1889 } 1890 1891 static int 1892 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1893 { 1894 const char *path, *pr_path; 1895 size_t pr_pathlen; 1896 bool visible; 1897 1898 sx_assert(&shm_dict_lock, SA_LOCKED); 1899 kif->kf_type = KF_TYPE_SHM; 1900 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1901 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1902 if (shmfd->shm_path != NULL) { 1903 if (shmfd->shm_path != NULL) { 1904 path = shmfd->shm_path; 1905 pr_path = curthread->td_ucred->cr_prison->pr_path; 1906 if (strcmp(pr_path, "/") != 0) { 1907 /* Return the jail-rooted pathname. */ 1908 pr_pathlen = strlen(pr_path); 1909 visible = strncmp(path, pr_path, pr_pathlen) 1910 == 0 && path[pr_pathlen] == '/'; 1911 if (list && !visible) 1912 return (EPERM); 1913 if (visible) 1914 path += pr_pathlen; 1915 } 1916 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1917 } 1918 } 1919 return (0); 1920 } 1921 1922 static int 1923 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1924 struct filedesc *fdp __unused) 1925 { 1926 int res; 1927 1928 sx_slock(&shm_dict_lock); 1929 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1930 sx_sunlock(&shm_dict_lock); 1931 return (res); 1932 } 1933 1934 static int 1935 shm_add_seals(struct file *fp, int seals) 1936 { 1937 struct shmfd *shmfd; 1938 void *rl_cookie; 1939 vm_ooffset_t writemappings; 1940 int error, nseals; 1941 1942 error = 0; 1943 shmfd = fp->f_data; 1944 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1945 1946 /* Even already-set seals should result in EPERM. */ 1947 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1948 error = EPERM; 1949 goto out; 1950 } 1951 nseals = seals & ~shmfd->shm_seals; 1952 if ((nseals & F_SEAL_WRITE) != 0) { 1953 if (shm_largepage(shmfd)) { 1954 error = ENOTSUP; 1955 goto out; 1956 } 1957 1958 /* 1959 * The rangelock above prevents writable mappings from being 1960 * added after we've started applying seals. The RLOCK here 1961 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1962 * writemappings will be done without a rangelock. 1963 */ 1964 VM_OBJECT_RLOCK(shmfd->shm_object); 1965 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1966 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1967 /* kmappings are also writable */ 1968 if (writemappings > 0) { 1969 error = EBUSY; 1970 goto out; 1971 } 1972 } 1973 shmfd->shm_seals |= nseals; 1974 out: 1975 shm_rangelock_unlock(shmfd, rl_cookie); 1976 return (error); 1977 } 1978 1979 static int 1980 shm_get_seals(struct file *fp, int *seals) 1981 { 1982 struct shmfd *shmfd; 1983 1984 shmfd = fp->f_data; 1985 *seals = shmfd->shm_seals; 1986 return (0); 1987 } 1988 1989 static int 1990 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 1991 { 1992 vm_object_t object; 1993 vm_pindex_t pistart, pi, piend; 1994 vm_ooffset_t off, len; 1995 int startofs, endofs, end; 1996 int error; 1997 1998 off = *offset; 1999 len = *length; 2000 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 2001 if (off + len > shmfd->shm_size) 2002 len = shmfd->shm_size - off; 2003 object = shmfd->shm_object; 2004 startofs = off & PAGE_MASK; 2005 endofs = (off + len) & PAGE_MASK; 2006 pistart = OFF_TO_IDX(off); 2007 piend = OFF_TO_IDX(off + len); 2008 pi = OFF_TO_IDX(off + PAGE_MASK); 2009 error = 0; 2010 2011 /* Handle the case when offset is on or beyond shm size. */ 2012 if ((off_t)len <= 0) { 2013 *length = 0; 2014 return (0); 2015 } 2016 2017 VM_OBJECT_WLOCK(object); 2018 2019 if (startofs != 0) { 2020 end = pistart != piend ? PAGE_SIZE : endofs; 2021 error = shm_partial_page_invalidate(object, pistart, startofs, 2022 end); 2023 if (error) 2024 goto out; 2025 off += end - startofs; 2026 len -= end - startofs; 2027 } 2028 2029 if (pi < piend) { 2030 vm_object_page_remove(object, pi, piend, 0); 2031 off += IDX_TO_OFF(piend - pi); 2032 len -= IDX_TO_OFF(piend - pi); 2033 } 2034 2035 if (endofs != 0 && pistart != piend) { 2036 error = shm_partial_page_invalidate(object, piend, 0, endofs); 2037 if (error) 2038 goto out; 2039 off += endofs; 2040 len -= endofs; 2041 } 2042 2043 out: 2044 VM_OBJECT_WUNLOCK(shmfd->shm_object); 2045 *offset = off; 2046 *length = len; 2047 return (error); 2048 } 2049 2050 static int 2051 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 2052 struct ucred *active_cred, struct thread *td) 2053 { 2054 void *rl_cookie; 2055 struct shmfd *shmfd; 2056 off_t off, len; 2057 int error; 2058 2059 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd")); 2060 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0, 2061 ("shm_fspacectl: non-zero flags")); 2062 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset, 2063 ("shm_fspacectl: offset/length overflow or underflow")); 2064 error = EINVAL; 2065 shmfd = fp->f_data; 2066 off = *offset; 2067 len = *length; 2068 2069 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len); 2070 switch (cmd) { 2071 case SPACECTL_DEALLOC: 2072 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2073 error = EPERM; 2074 break; 2075 } 2076 error = shm_deallocate(shmfd, &off, &len, flags); 2077 *offset = off; 2078 *length = len; 2079 break; 2080 default: 2081 __assert_unreachable(); 2082 } 2083 shm_rangelock_unlock(shmfd, rl_cookie); 2084 return (error); 2085 } 2086 2087 2088 static int 2089 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2090 { 2091 void *rl_cookie; 2092 struct shmfd *shmfd; 2093 size_t size; 2094 int error; 2095 2096 /* This assumes that the caller already checked for overflow. */ 2097 error = 0; 2098 shmfd = fp->f_data; 2099 size = offset + len; 2100 2101 /* 2102 * Just grab the rangelock for the range that we may be attempting to 2103 * grow, rather than blocking read/write for regions we won't be 2104 * touching while this (potential) resize is in progress. Other 2105 * attempts to resize the shmfd will have to take a write lock from 0 to 2106 * OFF_MAX, so this being potentially beyond the current usable range of 2107 * the shmfd is not necessarily a concern. If other mechanisms are 2108 * added to grow a shmfd, this may need to be re-evaluated. 2109 */ 2110 rl_cookie = shm_rangelock_wlock(shmfd, offset, size); 2111 if (size > shmfd->shm_size) 2112 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2113 shm_rangelock_unlock(shmfd, rl_cookie); 2114 /* Translate to posix_fallocate(2) return value as needed. */ 2115 if (error == ENOMEM) 2116 error = ENOSPC; 2117 return (error); 2118 } 2119 2120 static int 2121 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2122 { 2123 struct shm_mapping *shmm; 2124 struct sbuf sb; 2125 struct kinfo_file kif; 2126 u_long i; 2127 int error, error2; 2128 2129 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2130 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2131 error = 0; 2132 sx_slock(&shm_dict_lock); 2133 for (i = 0; i < shm_hash + 1; i++) { 2134 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2135 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2136 &kif, true); 2137 if (error == EPERM) { 2138 error = 0; 2139 continue; 2140 } 2141 if (error != 0) 2142 break; 2143 pack_kinfo(&kif); 2144 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2145 0 : ENOMEM; 2146 if (error != 0) 2147 break; 2148 } 2149 } 2150 sx_sunlock(&shm_dict_lock); 2151 error2 = sbuf_finish(&sb); 2152 sbuf_delete(&sb); 2153 return (error != 0 ? error : error2); 2154 } 2155 2156 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2157 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2158 NULL, 0, sysctl_posix_shm_list, "", 2159 "POSIX SHM list"); 2160 2161 int 2162 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2163 struct filecaps *caps) 2164 { 2165 2166 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2167 } 2168 2169 /* 2170 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2171 * caller, and libc will enforce it for the traditional shm_open() call. This 2172 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2173 * interface also includes a 'name' argument that is currently unused, but could 2174 * potentially be exported later via some interface for debugging purposes. 2175 * From the kernel's perspective, it is optional. Individual consumers like 2176 * memfd_create() may require it in order to be compatible with other systems 2177 * implementing the same function. 2178 */ 2179 int 2180 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2181 { 2182 2183 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2184 uap->shmflags, NULL, uap->name)); 2185 } 2186