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); 881 if (error == ENOMEM) 882 error = vm_wait_intr(object); 883 if (error != 0) { 884 VM_OBJECT_WLOCK(object); 885 return (error); 886 } 887 try++; 888 VM_OBJECT_WLOCK(object); 889 continue; 890 } 891 try = 0; 892 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 893 if ((m[i].flags & PG_ZERO) == 0) 894 pmap_zero_page(&m[i]); 895 vm_page_valid(&m[i]); 896 vm_page_xunbusy(&m[i]); 897 } 898 object->size += OFF_TO_IDX(pagesizes[psind]); 899 shmfd->shm_size += pagesizes[psind]; 900 atomic_add_long(&count_largepages[psind], 1); 901 vm_wire_add(atop(pagesizes[psind])); 902 } 903 return (0); 904 } 905 906 static int 907 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 908 { 909 int error; 910 911 VM_OBJECT_WLOCK(shmfd->shm_object); 912 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 913 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 914 rl_cookie); 915 VM_OBJECT_WUNLOCK(shmfd->shm_object); 916 return (error); 917 } 918 919 int 920 shm_dotruncate(struct shmfd *shmfd, off_t length) 921 { 922 void *rl_cookie; 923 int error; 924 925 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 926 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 927 shm_rangelock_unlock(shmfd, rl_cookie); 928 return (error); 929 } 930 931 /* 932 * shmfd object management including creation and reference counting 933 * routines. 934 */ 935 struct shmfd * 936 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 937 { 938 struct shmfd *shmfd; 939 vm_object_t obj; 940 941 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 942 shmfd->shm_size = 0; 943 shmfd->shm_uid = ucred->cr_uid; 944 shmfd->shm_gid = ucred->cr_gid; 945 shmfd->shm_mode = mode; 946 if (largepage) { 947 shmfd->shm_object = phys_pager_allocate(NULL, 948 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 949 VM_PROT_DEFAULT, 0, ucred); 950 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 951 } else { 952 obj = vm_pager_allocate(shmfd_pager_type, NULL, 953 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 954 VM_OBJECT_WLOCK(obj); 955 obj->un_pager.swp.swp_priv = shmfd; 956 VM_OBJECT_WUNLOCK(obj); 957 shmfd->shm_object = obj; 958 } 959 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 960 vfs_timestamp(&shmfd->shm_birthtime); 961 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 962 shmfd->shm_birthtime; 963 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 964 refcount_init(&shmfd->shm_refs, 1); 965 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 966 rangelock_init(&shmfd->shm_rl); 967 #ifdef MAC 968 mac_posixshm_init(shmfd); 969 mac_posixshm_create(ucred, shmfd); 970 #endif 971 972 return (shmfd); 973 } 974 975 struct shmfd * 976 shm_hold(struct shmfd *shmfd) 977 { 978 979 refcount_acquire(&shmfd->shm_refs); 980 return (shmfd); 981 } 982 983 void 984 shm_drop(struct shmfd *shmfd) 985 { 986 vm_object_t obj; 987 988 if (refcount_release(&shmfd->shm_refs)) { 989 #ifdef MAC 990 mac_posixshm_destroy(shmfd); 991 #endif 992 rangelock_destroy(&shmfd->shm_rl); 993 mtx_destroy(&shmfd->shm_mtx); 994 obj = shmfd->shm_object; 995 if (!shm_largepage(shmfd)) { 996 VM_OBJECT_WLOCK(obj); 997 obj->un_pager.swp.swp_priv = NULL; 998 VM_OBJECT_WUNLOCK(obj); 999 } 1000 vm_object_deallocate(obj); 1001 free(shmfd, M_SHMFD); 1002 } 1003 } 1004 1005 /* 1006 * Determine if the credentials have sufficient permissions for a 1007 * specified combination of FREAD and FWRITE. 1008 */ 1009 int 1010 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 1011 { 1012 accmode_t accmode; 1013 int error; 1014 1015 accmode = 0; 1016 if (flags & FREAD) 1017 accmode |= VREAD; 1018 if (flags & FWRITE) 1019 accmode |= VWRITE; 1020 mtx_lock(&shm_timestamp_lock); 1021 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1022 accmode, ucred); 1023 mtx_unlock(&shm_timestamp_lock); 1024 return (error); 1025 } 1026 1027 static void 1028 shm_init(void *arg) 1029 { 1030 char name[32]; 1031 int i; 1032 1033 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 1034 sx_init(&shm_dict_lock, "shm dictionary"); 1035 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 1036 new_unrhdr64(&shm_ino_unr, 1); 1037 shm_dev_ino = devfs_alloc_cdp_inode(); 1038 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 1039 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops, 1040 OBJT_SWAP); 1041 MPASS(shmfd_pager_type != -1); 1042 1043 for (i = 1; i < MAXPAGESIZES; i++) { 1044 if (pagesizes[i] == 0) 1045 break; 1046 #define M (1024 * 1024) 1047 #define G (1024 * M) 1048 if (pagesizes[i] >= G) 1049 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 1050 else if (pagesizes[i] >= M) 1051 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 1052 else 1053 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 1054 #undef G 1055 #undef M 1056 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 1057 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 1058 "number of non-transient largepages allocated"); 1059 } 1060 } 1061 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 1062 1063 /* 1064 * Remove all shared memory objects that belong to a prison. 1065 */ 1066 void 1067 shm_remove_prison(struct prison *pr) 1068 { 1069 struct shm_mapping *shmm, *tshmm; 1070 u_long i; 1071 1072 sx_xlock(&shm_dict_lock); 1073 for (i = 0; i < shm_hash + 1; i++) { 1074 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) { 1075 if (shmm->sm_shmfd->shm_object->cred && 1076 shmm->sm_shmfd->shm_object->cred->cr_prison == pr) 1077 shm_doremove(shmm); 1078 } 1079 } 1080 sx_xunlock(&shm_dict_lock); 1081 } 1082 1083 /* 1084 * Dictionary management. We maintain an in-kernel dictionary to map 1085 * paths to shmfd objects. We use the FNV hash on the path to store 1086 * the mappings in a hash table. 1087 */ 1088 static struct shmfd * 1089 shm_lookup(char *path, Fnv32_t fnv) 1090 { 1091 struct shm_mapping *map; 1092 1093 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1094 if (map->sm_fnv != fnv) 1095 continue; 1096 if (strcmp(map->sm_path, path) == 0) 1097 return (map->sm_shmfd); 1098 } 1099 1100 return (NULL); 1101 } 1102 1103 static void 1104 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 1105 { 1106 struct shm_mapping *map; 1107 1108 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 1109 map->sm_path = path; 1110 map->sm_fnv = fnv; 1111 map->sm_shmfd = shm_hold(shmfd); 1112 shmfd->shm_path = path; 1113 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 1114 } 1115 1116 static int 1117 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1118 { 1119 struct shm_mapping *map; 1120 int error; 1121 1122 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1123 if (map->sm_fnv != fnv) 1124 continue; 1125 if (strcmp(map->sm_path, path) == 0) { 1126 #ifdef MAC 1127 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1128 if (error) 1129 return (error); 1130 #endif 1131 error = shm_access(map->sm_shmfd, ucred, 1132 FREAD | FWRITE); 1133 if (error) 1134 return (error); 1135 shm_doremove(map); 1136 return (0); 1137 } 1138 } 1139 1140 return (ENOENT); 1141 } 1142 1143 static void 1144 shm_doremove(struct shm_mapping *map) 1145 { 1146 map->sm_shmfd->shm_path = NULL; 1147 LIST_REMOVE(map, sm_link); 1148 shm_drop(map->sm_shmfd); 1149 free(map->sm_path, M_SHMFD); 1150 free(map, M_SHMFD); 1151 } 1152 1153 int 1154 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1155 int shmflags, struct filecaps *fcaps, const char *name __unused) 1156 { 1157 struct pwddesc *pdp; 1158 struct shmfd *shmfd; 1159 struct file *fp; 1160 char *path; 1161 void *rl_cookie; 1162 Fnv32_t fnv; 1163 mode_t cmode; 1164 int error, fd, initial_seals; 1165 bool largepage; 1166 1167 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1168 SHM_LARGEPAGE)) != 0) 1169 return (EINVAL); 1170 1171 initial_seals = F_SEAL_SEAL; 1172 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1173 initial_seals &= ~F_SEAL_SEAL; 1174 1175 #ifdef CAPABILITY_MODE 1176 /* 1177 * shm_open(2) is only allowed for anonymous objects. 1178 */ 1179 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1180 return (ECAPMODE); 1181 #endif 1182 1183 AUDIT_ARG_FFLAGS(flags); 1184 AUDIT_ARG_MODE(mode); 1185 1186 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1187 return (EINVAL); 1188 1189 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1190 return (EINVAL); 1191 1192 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1193 if (largepage && !PMAP_HAS_LARGEPAGES) 1194 return (ENOTTY); 1195 1196 /* 1197 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1198 * If the decision is made later to allow additional seals, care must be 1199 * taken below to ensure that the seals are properly set if the shmfd 1200 * already existed -- this currently assumes that only F_SEAL_SEAL can 1201 * be set and doesn't take further precautions to ensure the validity of 1202 * the seals being added with respect to current mappings. 1203 */ 1204 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1205 return (EINVAL); 1206 1207 pdp = td->td_proc->p_pd; 1208 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1209 1210 /* 1211 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1212 * by POSIX. We allow it to be unset here so that an in-kernel 1213 * interface may be written as a thin layer around shm, optionally not 1214 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1215 * in sys_shm_open() to keep this implementation compliant. 1216 */ 1217 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1218 if (error) 1219 return (error); 1220 1221 /* A SHM_ANON path pointer creates an anonymous object. */ 1222 if (userpath == SHM_ANON) { 1223 /* A read-only anonymous object is pointless. */ 1224 if ((flags & O_ACCMODE) == O_RDONLY) { 1225 fdclose(td, fp, fd); 1226 fdrop(fp, td); 1227 return (EINVAL); 1228 } 1229 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1230 shmfd->shm_seals = initial_seals; 1231 shmfd->shm_flags = shmflags; 1232 } else { 1233 error = shm_copyin_path(td, userpath, &path); 1234 if (error != 0) { 1235 fdclose(td, fp, fd); 1236 fdrop(fp, td); 1237 return (error); 1238 } 1239 1240 AUDIT_ARG_UPATH1_CANON(path); 1241 fnv = fnv_32_str(path, FNV1_32_INIT); 1242 sx_xlock(&shm_dict_lock); 1243 shmfd = shm_lookup(path, fnv); 1244 if (shmfd == NULL) { 1245 /* Object does not yet exist, create it if requested. */ 1246 if (flags & O_CREAT) { 1247 #ifdef MAC 1248 error = mac_posixshm_check_create(td->td_ucred, 1249 path); 1250 if (error == 0) { 1251 #endif 1252 shmfd = shm_alloc(td->td_ucred, cmode, 1253 largepage); 1254 shmfd->shm_seals = initial_seals; 1255 shmfd->shm_flags = shmflags; 1256 shm_insert(path, fnv, shmfd); 1257 #ifdef MAC 1258 } 1259 #endif 1260 } else { 1261 free(path, M_SHMFD); 1262 error = ENOENT; 1263 } 1264 } else { 1265 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1266 1267 /* 1268 * kern_shm_open() likely shouldn't ever error out on 1269 * trying to set a seal that already exists, unlike 1270 * F_ADD_SEALS. This would break terribly as 1271 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1272 * historical behavior where the underlying file could 1273 * not be sealed. 1274 */ 1275 initial_seals &= ~shmfd->shm_seals; 1276 1277 /* 1278 * Object already exists, obtain a new 1279 * reference if requested and permitted. 1280 */ 1281 free(path, M_SHMFD); 1282 1283 /* 1284 * initial_seals can't set additional seals if we've 1285 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1286 * then we've already removed that one from 1287 * initial_seals. This is currently redundant as we 1288 * only allow setting F_SEAL_SEAL at creation time, but 1289 * it's cheap to check and decreases the effort required 1290 * to allow additional seals. 1291 */ 1292 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1293 initial_seals != 0) 1294 error = EPERM; 1295 else if ((flags & (O_CREAT | O_EXCL)) == 1296 (O_CREAT | O_EXCL)) 1297 error = EEXIST; 1298 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1299 error = EINVAL; 1300 else { 1301 #ifdef MAC 1302 error = mac_posixshm_check_open(td->td_ucred, 1303 shmfd, FFLAGS(flags & O_ACCMODE)); 1304 if (error == 0) 1305 #endif 1306 error = shm_access(shmfd, td->td_ucred, 1307 FFLAGS(flags & O_ACCMODE)); 1308 } 1309 1310 /* 1311 * Truncate the file back to zero length if 1312 * O_TRUNC was specified and the object was 1313 * opened with read/write. 1314 */ 1315 if (error == 0 && 1316 (flags & (O_ACCMODE | O_TRUNC)) == 1317 (O_RDWR | O_TRUNC)) { 1318 VM_OBJECT_WLOCK(shmfd->shm_object); 1319 #ifdef MAC 1320 error = mac_posixshm_check_truncate( 1321 td->td_ucred, fp->f_cred, shmfd); 1322 if (error == 0) 1323 #endif 1324 error = shm_dotruncate_locked(shmfd, 0, 1325 rl_cookie); 1326 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1327 } 1328 if (error == 0) { 1329 /* 1330 * Currently we only allow F_SEAL_SEAL to be 1331 * set initially. As noted above, this would 1332 * need to be reworked should that change. 1333 */ 1334 shmfd->shm_seals |= initial_seals; 1335 shm_hold(shmfd); 1336 } 1337 shm_rangelock_unlock(shmfd, rl_cookie); 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 | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0) 1553 return (EINVAL); 1554 1555 vms = td->td_proc->p_vmspace; 1556 curmap = map == &vms->vm_map; 1557 if (curmap) { 1558 error = kern_mmap_racct_check(td, map, size); 1559 if (error != 0) 1560 return (error); 1561 } 1562 1563 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1564 docow |= MAP_INHERIT_SHARE; 1565 if ((flags & MAP_NOCORE) != 0) 1566 docow |= MAP_DISABLE_COREDUMP; 1567 1568 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1569 if ((foff & mask) != 0) 1570 return (EINVAL); 1571 maxaddr = vm_map_max(map); 1572 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1573 maxaddr = MAP_32BIT_MAX_ADDR; 1574 if (size == 0 || (size & mask) != 0 || 1575 (*addr != 0 && ((*addr & mask) != 0 || 1576 *addr + size < *addr || *addr + size > maxaddr))) 1577 return (EINVAL); 1578 1579 align = flags & MAP_ALIGNMENT_MASK; 1580 if (align == 0) { 1581 align = pagesizes[shmfd->shm_lp_psind]; 1582 } else if (align == MAP_ALIGNED_SUPER) { 1583 if (shmfd->shm_lp_psind != 1) 1584 return (EINVAL); 1585 align = pagesizes[1]; 1586 } else { 1587 align >>= MAP_ALIGNMENT_SHIFT; 1588 align = 1ULL << align; 1589 /* Also handles overflow. */ 1590 if (align < pagesizes[shmfd->shm_lp_psind]) 1591 return (EINVAL); 1592 } 1593 1594 vm_map_lock(map); 1595 if ((flags & MAP_FIXED) == 0) { 1596 try = 1; 1597 if (curmap && (*addr == 0 || 1598 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1599 *addr < round_page((vm_offset_t)vms->vm_daddr + 1600 lim_max(td, RLIMIT_DATA))))) { 1601 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1602 lim_max(td, RLIMIT_DATA), 1603 pagesizes[shmfd->shm_lp_psind]); 1604 } 1605 again: 1606 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1607 if (rv != KERN_SUCCESS) { 1608 if (try == 1) { 1609 try = 2; 1610 *addr = vm_map_min(map); 1611 if ((*addr & mask) != 0) 1612 *addr = (*addr + mask) & mask; 1613 goto again; 1614 } 1615 goto fail1; 1616 } 1617 } else if ((flags & MAP_EXCL) == 0) { 1618 rv = vm_map_delete(map, *addr, *addr + size); 1619 if (rv != KERN_SUCCESS) 1620 goto fail1; 1621 } else { 1622 error = ENOSPC; 1623 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1624 goto fail; 1625 next_entry = vm_map_entry_succ(prev_entry); 1626 if (next_entry->start < *addr + size) 1627 goto fail; 1628 } 1629 1630 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1631 prot, max_prot, docow); 1632 fail1: 1633 error = vm_mmap_to_errno(rv); 1634 fail: 1635 vm_map_unlock(map); 1636 return (error); 1637 } 1638 1639 static int 1640 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1641 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1642 vm_ooffset_t foff, struct thread *td) 1643 { 1644 struct shmfd *shmfd; 1645 vm_prot_t maxprot; 1646 int error; 1647 bool writecnt; 1648 void *rl_cookie; 1649 1650 shmfd = fp->f_data; 1651 maxprot = VM_PROT_NONE; 1652 1653 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize); 1654 /* FREAD should always be set. */ 1655 if ((fp->f_flag & FREAD) != 0) 1656 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1657 1658 /* 1659 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1660 * mapping with a write seal applied. Private mappings are always 1661 * writeable. 1662 */ 1663 if ((flags & MAP_SHARED) == 0) { 1664 cap_maxprot |= VM_PROT_WRITE; 1665 maxprot |= VM_PROT_WRITE; 1666 writecnt = false; 1667 } else { 1668 if ((fp->f_flag & FWRITE) != 0 && 1669 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1670 maxprot |= VM_PROT_WRITE; 1671 1672 /* 1673 * Any mappings from a writable descriptor may be upgraded to 1674 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1675 * applied between the open and subsequent mmap(2). We want to 1676 * reject application of a write seal as long as any such 1677 * mapping exists so that the seal cannot be trivially bypassed. 1678 */ 1679 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1680 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1681 error = EACCES; 1682 goto out; 1683 } 1684 } 1685 maxprot &= cap_maxprot; 1686 1687 /* See comment in vn_mmap(). */ 1688 if ( 1689 #ifdef _LP64 1690 objsize > OFF_MAX || 1691 #endif 1692 foff > OFF_MAX - objsize) { 1693 error = EINVAL; 1694 goto out; 1695 } 1696 1697 #ifdef MAC 1698 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1699 if (error != 0) 1700 goto out; 1701 #endif 1702 1703 mtx_lock(&shm_timestamp_lock); 1704 vfs_timestamp(&shmfd->shm_atime); 1705 mtx_unlock(&shm_timestamp_lock); 1706 vm_object_reference(shmfd->shm_object); 1707 1708 if (shm_largepage(shmfd)) { 1709 writecnt = false; 1710 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1711 maxprot, flags, foff, td); 1712 } else { 1713 if (writecnt) { 1714 vm_pager_update_writecount(shmfd->shm_object, 0, 1715 objsize); 1716 } 1717 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1718 shmfd->shm_object, foff, writecnt, td); 1719 } 1720 if (error != 0) { 1721 if (writecnt) 1722 vm_pager_release_writecount(shmfd->shm_object, 0, 1723 objsize); 1724 vm_object_deallocate(shmfd->shm_object); 1725 } 1726 out: 1727 shm_rangelock_unlock(shmfd, rl_cookie); 1728 return (error); 1729 } 1730 1731 static int 1732 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1733 struct thread *td) 1734 { 1735 struct shmfd *shmfd; 1736 int error; 1737 1738 error = 0; 1739 shmfd = fp->f_data; 1740 mtx_lock(&shm_timestamp_lock); 1741 /* 1742 * SUSv4 says that x bits of permission need not be affected. 1743 * Be consistent with our shm_open there. 1744 */ 1745 #ifdef MAC 1746 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1747 if (error != 0) 1748 goto out; 1749 #endif 1750 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1751 VADMIN, active_cred); 1752 if (error != 0) 1753 goto out; 1754 shmfd->shm_mode = mode & ACCESSPERMS; 1755 out: 1756 mtx_unlock(&shm_timestamp_lock); 1757 return (error); 1758 } 1759 1760 static int 1761 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1762 struct thread *td) 1763 { 1764 struct shmfd *shmfd; 1765 int error; 1766 1767 error = 0; 1768 shmfd = fp->f_data; 1769 mtx_lock(&shm_timestamp_lock); 1770 #ifdef MAC 1771 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1772 if (error != 0) 1773 goto out; 1774 #endif 1775 if (uid == (uid_t)-1) 1776 uid = shmfd->shm_uid; 1777 if (gid == (gid_t)-1) 1778 gid = shmfd->shm_gid; 1779 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1780 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1781 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1782 goto out; 1783 shmfd->shm_uid = uid; 1784 shmfd->shm_gid = gid; 1785 out: 1786 mtx_unlock(&shm_timestamp_lock); 1787 return (error); 1788 } 1789 1790 /* 1791 * Helper routines to allow the backing object of a shared memory file 1792 * descriptor to be mapped in the kernel. 1793 */ 1794 int 1795 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1796 { 1797 struct shmfd *shmfd; 1798 vm_offset_t kva, ofs; 1799 vm_object_t obj; 1800 int rv; 1801 1802 if (fp->f_type != DTYPE_SHM) 1803 return (EINVAL); 1804 shmfd = fp->f_data; 1805 obj = shmfd->shm_object; 1806 VM_OBJECT_WLOCK(obj); 1807 /* 1808 * XXXRW: This validation is probably insufficient, and subject to 1809 * sign errors. It should be fixed. 1810 */ 1811 if (offset >= shmfd->shm_size || 1812 offset + size > round_page(shmfd->shm_size)) { 1813 VM_OBJECT_WUNLOCK(obj); 1814 return (EINVAL); 1815 } 1816 1817 shmfd->shm_kmappings++; 1818 vm_object_reference_locked(obj); 1819 VM_OBJECT_WUNLOCK(obj); 1820 1821 /* Map the object into the kernel_map and wire it. */ 1822 kva = vm_map_min(kernel_map); 1823 ofs = offset & PAGE_MASK; 1824 offset = trunc_page(offset); 1825 size = round_page(size + ofs); 1826 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1827 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1828 VM_PROT_READ | VM_PROT_WRITE, 0); 1829 if (rv == KERN_SUCCESS) { 1830 rv = vm_map_wire(kernel_map, kva, kva + size, 1831 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1832 if (rv == KERN_SUCCESS) { 1833 *memp = (void *)(kva + ofs); 1834 return (0); 1835 } 1836 vm_map_remove(kernel_map, kva, kva + size); 1837 } else 1838 vm_object_deallocate(obj); 1839 1840 /* On failure, drop our mapping reference. */ 1841 VM_OBJECT_WLOCK(obj); 1842 shmfd->shm_kmappings--; 1843 VM_OBJECT_WUNLOCK(obj); 1844 1845 return (vm_mmap_to_errno(rv)); 1846 } 1847 1848 /* 1849 * We require the caller to unmap the entire entry. This allows us to 1850 * safely decrement shm_kmappings when a mapping is removed. 1851 */ 1852 int 1853 shm_unmap(struct file *fp, void *mem, size_t size) 1854 { 1855 struct shmfd *shmfd; 1856 vm_map_entry_t entry; 1857 vm_offset_t kva, ofs; 1858 vm_object_t obj; 1859 vm_pindex_t pindex; 1860 vm_prot_t prot; 1861 boolean_t wired; 1862 vm_map_t map; 1863 int rv; 1864 1865 if (fp->f_type != DTYPE_SHM) 1866 return (EINVAL); 1867 shmfd = fp->f_data; 1868 kva = (vm_offset_t)mem; 1869 ofs = kva & PAGE_MASK; 1870 kva = trunc_page(kva); 1871 size = round_page(size + ofs); 1872 map = kernel_map; 1873 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1874 &obj, &pindex, &prot, &wired); 1875 if (rv != KERN_SUCCESS) 1876 return (EINVAL); 1877 if (entry->start != kva || entry->end != kva + size) { 1878 vm_map_lookup_done(map, entry); 1879 return (EINVAL); 1880 } 1881 vm_map_lookup_done(map, entry); 1882 if (obj != shmfd->shm_object) 1883 return (EINVAL); 1884 vm_map_remove(map, kva, kva + size); 1885 VM_OBJECT_WLOCK(obj); 1886 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1887 shmfd->shm_kmappings--; 1888 VM_OBJECT_WUNLOCK(obj); 1889 return (0); 1890 } 1891 1892 static int 1893 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1894 { 1895 const char *path, *pr_path; 1896 size_t pr_pathlen; 1897 bool visible; 1898 1899 sx_assert(&shm_dict_lock, SA_LOCKED); 1900 kif->kf_type = KF_TYPE_SHM; 1901 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1902 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1903 if (shmfd->shm_path != NULL) { 1904 if (shmfd->shm_path != NULL) { 1905 path = shmfd->shm_path; 1906 pr_path = curthread->td_ucred->cr_prison->pr_path; 1907 if (strcmp(pr_path, "/") != 0) { 1908 /* Return the jail-rooted pathname. */ 1909 pr_pathlen = strlen(pr_path); 1910 visible = strncmp(path, pr_path, pr_pathlen) 1911 == 0 && path[pr_pathlen] == '/'; 1912 if (list && !visible) 1913 return (EPERM); 1914 if (visible) 1915 path += pr_pathlen; 1916 } 1917 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1918 } 1919 } 1920 return (0); 1921 } 1922 1923 static int 1924 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1925 struct filedesc *fdp __unused) 1926 { 1927 int res; 1928 1929 sx_slock(&shm_dict_lock); 1930 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1931 sx_sunlock(&shm_dict_lock); 1932 return (res); 1933 } 1934 1935 static int 1936 shm_add_seals(struct file *fp, int seals) 1937 { 1938 struct shmfd *shmfd; 1939 void *rl_cookie; 1940 vm_ooffset_t writemappings; 1941 int error, nseals; 1942 1943 error = 0; 1944 shmfd = fp->f_data; 1945 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1946 1947 /* Even already-set seals should result in EPERM. */ 1948 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1949 error = EPERM; 1950 goto out; 1951 } 1952 nseals = seals & ~shmfd->shm_seals; 1953 if ((nseals & F_SEAL_WRITE) != 0) { 1954 if (shm_largepage(shmfd)) { 1955 error = ENOTSUP; 1956 goto out; 1957 } 1958 1959 /* 1960 * The rangelock above prevents writable mappings from being 1961 * added after we've started applying seals. The RLOCK here 1962 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1963 * writemappings will be done without a rangelock. 1964 */ 1965 VM_OBJECT_RLOCK(shmfd->shm_object); 1966 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1967 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1968 /* kmappings are also writable */ 1969 if (writemappings > 0) { 1970 error = EBUSY; 1971 goto out; 1972 } 1973 } 1974 shmfd->shm_seals |= nseals; 1975 out: 1976 shm_rangelock_unlock(shmfd, rl_cookie); 1977 return (error); 1978 } 1979 1980 static int 1981 shm_get_seals(struct file *fp, int *seals) 1982 { 1983 struct shmfd *shmfd; 1984 1985 shmfd = fp->f_data; 1986 *seals = shmfd->shm_seals; 1987 return (0); 1988 } 1989 1990 static int 1991 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 1992 { 1993 vm_object_t object; 1994 vm_pindex_t pistart, pi, piend; 1995 vm_ooffset_t off, len; 1996 int startofs, endofs, end; 1997 int error; 1998 1999 off = *offset; 2000 len = *length; 2001 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 2002 if (off + len > shmfd->shm_size) 2003 len = shmfd->shm_size - off; 2004 object = shmfd->shm_object; 2005 startofs = off & PAGE_MASK; 2006 endofs = (off + len) & PAGE_MASK; 2007 pistart = OFF_TO_IDX(off); 2008 piend = OFF_TO_IDX(off + len); 2009 pi = OFF_TO_IDX(off + PAGE_MASK); 2010 error = 0; 2011 2012 /* Handle the case when offset is on or beyond shm size. */ 2013 if ((off_t)len <= 0) { 2014 *length = 0; 2015 return (0); 2016 } 2017 2018 VM_OBJECT_WLOCK(object); 2019 2020 if (startofs != 0) { 2021 end = pistart != piend ? PAGE_SIZE : endofs; 2022 error = shm_partial_page_invalidate(object, pistart, startofs, 2023 end); 2024 if (error) 2025 goto out; 2026 off += end - startofs; 2027 len -= end - startofs; 2028 } 2029 2030 if (pi < piend) { 2031 vm_object_page_remove(object, pi, piend, 0); 2032 off += IDX_TO_OFF(piend - pi); 2033 len -= IDX_TO_OFF(piend - pi); 2034 } 2035 2036 if (endofs != 0 && pistart != piend) { 2037 error = shm_partial_page_invalidate(object, piend, 0, endofs); 2038 if (error) 2039 goto out; 2040 off += endofs; 2041 len -= endofs; 2042 } 2043 2044 out: 2045 VM_OBJECT_WUNLOCK(shmfd->shm_object); 2046 *offset = off; 2047 *length = len; 2048 return (error); 2049 } 2050 2051 static int 2052 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 2053 struct ucred *active_cred, struct thread *td) 2054 { 2055 void *rl_cookie; 2056 struct shmfd *shmfd; 2057 off_t off, len; 2058 int error; 2059 2060 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd")); 2061 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0, 2062 ("shm_fspacectl: non-zero flags")); 2063 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset, 2064 ("shm_fspacectl: offset/length overflow or underflow")); 2065 error = EINVAL; 2066 shmfd = fp->f_data; 2067 off = *offset; 2068 len = *length; 2069 2070 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len); 2071 switch (cmd) { 2072 case SPACECTL_DEALLOC: 2073 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2074 error = EPERM; 2075 break; 2076 } 2077 error = shm_deallocate(shmfd, &off, &len, flags); 2078 *offset = off; 2079 *length = len; 2080 break; 2081 default: 2082 __assert_unreachable(); 2083 } 2084 shm_rangelock_unlock(shmfd, rl_cookie); 2085 return (error); 2086 } 2087 2088 2089 static int 2090 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2091 { 2092 void *rl_cookie; 2093 struct shmfd *shmfd; 2094 size_t size; 2095 int error; 2096 2097 /* This assumes that the caller already checked for overflow. */ 2098 error = 0; 2099 shmfd = fp->f_data; 2100 size = offset + len; 2101 2102 /* 2103 * Just grab the rangelock for the range that we may be attempting to 2104 * grow, rather than blocking read/write for regions we won't be 2105 * touching while this (potential) resize is in progress. Other 2106 * attempts to resize the shmfd will have to take a write lock from 0 to 2107 * OFF_MAX, so this being potentially beyond the current usable range of 2108 * the shmfd is not necessarily a concern. If other mechanisms are 2109 * added to grow a shmfd, this may need to be re-evaluated. 2110 */ 2111 rl_cookie = shm_rangelock_wlock(shmfd, offset, size); 2112 if (size > shmfd->shm_size) 2113 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2114 shm_rangelock_unlock(shmfd, rl_cookie); 2115 /* Translate to posix_fallocate(2) return value as needed. */ 2116 if (error == ENOMEM) 2117 error = ENOSPC; 2118 return (error); 2119 } 2120 2121 static int 2122 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2123 { 2124 struct shm_mapping *shmm; 2125 struct sbuf sb; 2126 struct kinfo_file kif; 2127 u_long i; 2128 int error, error2; 2129 2130 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2131 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2132 error = 0; 2133 sx_slock(&shm_dict_lock); 2134 for (i = 0; i < shm_hash + 1; i++) { 2135 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2136 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2137 &kif, true); 2138 if (error == EPERM) { 2139 error = 0; 2140 continue; 2141 } 2142 if (error != 0) 2143 break; 2144 pack_kinfo(&kif); 2145 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2146 0 : ENOMEM; 2147 if (error != 0) 2148 break; 2149 } 2150 } 2151 sx_sunlock(&shm_dict_lock); 2152 error2 = sbuf_finish(&sb); 2153 sbuf_delete(&sb); 2154 return (error != 0 ? error : error2); 2155 } 2156 2157 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2158 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2159 NULL, 0, sysctl_posix_shm_list, "", 2160 "POSIX SHM list"); 2161 2162 int 2163 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2164 struct filecaps *caps) 2165 { 2166 2167 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2168 } 2169 2170 /* 2171 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2172 * caller, and libc will enforce it for the traditional shm_open() call. This 2173 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2174 * interface also includes a 'name' argument that is currently unused, but could 2175 * potentially be exported later via some interface for debugging purposes. 2176 * From the kernel's perspective, it is optional. Individual consumers like 2177 * memfd_create() may require it in order to be compatible with other systems 2178 * implementing the same function. 2179 */ 2180 int 2181 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2182 { 2183 2184 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2185 uap->shmflags, NULL, uap->name)); 2186 } 2187