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 const 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_cmp = file_kcmp_generic, 173 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 174 }; 175 176 FEATURE(posix_shm, "POSIX shared memory"); 177 178 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 179 ""); 180 181 static int largepage_reclaim_tries = 1; 182 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 183 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 184 "Number of contig reclaims before giving up for default alloc policy"); 185 186 #define shm_rangelock_unlock(shmfd, cookie) \ 187 rangelock_unlock(&(shmfd)->shm_rl, (cookie)) 188 #define shm_rangelock_rlock(shmfd, start, end) \ 189 rangelock_rlock(&(shmfd)->shm_rl, (start), (end)) 190 #define shm_rangelock_tryrlock(shmfd, start, end) \ 191 rangelock_tryrlock(&(shmfd)->shm_rl, (start), (end)) 192 #define shm_rangelock_wlock(shmfd, start, end) \ 193 rangelock_wlock(&(shmfd)->shm_rl, (start), (end)) 194 195 static int 196 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 197 { 198 vm_page_t m; 199 vm_pindex_t idx; 200 size_t tlen; 201 int error, offset, rv; 202 203 idx = OFF_TO_IDX(uio->uio_offset); 204 offset = uio->uio_offset & PAGE_MASK; 205 tlen = MIN(PAGE_SIZE - offset, len); 206 207 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 208 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 209 if (rv == VM_PAGER_OK) 210 goto found; 211 212 /* 213 * Read I/O without either a corresponding resident page or swap 214 * page: use zero_region. This is intended to avoid instantiating 215 * pages on read from a sparse region. 216 */ 217 VM_OBJECT_WLOCK(obj); 218 m = vm_page_lookup(obj, idx); 219 if (uio->uio_rw == UIO_READ && m == NULL && 220 !vm_pager_has_page(obj, idx, NULL, NULL)) { 221 VM_OBJECT_WUNLOCK(obj); 222 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 223 } 224 225 /* 226 * Although the tmpfs vnode lock is held here, it is 227 * nonetheless safe to sleep waiting for a free page. The 228 * pageout daemon does not need to acquire the tmpfs vnode 229 * lock to page out tobj's pages because tobj is a OBJT_SWAP 230 * type object. 231 */ 232 rv = vm_page_grab_valid(&m, obj, idx, 233 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 234 if (rv != VM_PAGER_OK) { 235 VM_OBJECT_WUNLOCK(obj); 236 if (bootverbose) { 237 printf("uiomove_object: vm_obj %p idx %jd " 238 "pager error %d\n", obj, idx, rv); 239 } 240 return (rv == VM_PAGER_AGAIN ? ENOSPC : EIO); 241 } 242 VM_OBJECT_WUNLOCK(obj); 243 244 found: 245 error = uiomove_fromphys(&m, offset, tlen, uio); 246 if (uio->uio_rw == UIO_WRITE && error == 0) 247 vm_page_set_dirty(m); 248 vm_page_activate(m); 249 vm_page_sunbusy(m); 250 251 return (error); 252 } 253 254 int 255 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 256 { 257 ssize_t resid; 258 size_t len; 259 int error; 260 261 error = 0; 262 while ((resid = uio->uio_resid) > 0) { 263 if (obj_size <= uio->uio_offset) 264 break; 265 len = MIN(obj_size - uio->uio_offset, resid); 266 if (len == 0) 267 break; 268 error = uiomove_object_page(obj, len, uio); 269 if (error != 0 || resid == uio->uio_resid) 270 break; 271 } 272 return (error); 273 } 274 275 static u_long count_largepages[MAXPAGESIZES]; 276 277 static int 278 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 279 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 280 { 281 vm_page_t m __diagused; 282 int psind; 283 284 psind = object->un_pager.phys.data_val; 285 if (psind == 0 || pidx >= object->size) 286 return (VM_PAGER_FAIL); 287 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 288 289 /* 290 * We only busy the first page in the superpage run. It is 291 * useless to busy whole run since we only remove full 292 * superpage, and it takes too long to busy e.g. 512 * 512 == 293 * 262144 pages constituing 1G amd64 superage. 294 */ 295 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 296 MPASS(m != NULL); 297 298 *last = *first + atop(pagesizes[psind]) - 1; 299 return (VM_PAGER_OK); 300 } 301 302 static boolean_t 303 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 304 int *before, int *after) 305 { 306 int psind; 307 308 psind = object->un_pager.phys.data_val; 309 if (psind == 0 || pindex >= object->size) 310 return (FALSE); 311 if (before != NULL) { 312 *before = pindex - rounddown2(pindex, pagesizes[psind] / 313 PAGE_SIZE); 314 } 315 if (after != NULL) { 316 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 317 pindex; 318 } 319 return (TRUE); 320 } 321 322 static void 323 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 324 vm_ooffset_t foff, struct ucred *cred) 325 { 326 } 327 328 static void 329 shm_largepage_phys_dtor(vm_object_t object) 330 { 331 int psind; 332 333 psind = object->un_pager.phys.data_val; 334 if (psind != 0) { 335 atomic_subtract_long(&count_largepages[psind], 336 object->size / (pagesizes[psind] / PAGE_SIZE)); 337 vm_wire_sub(object->size); 338 } else { 339 KASSERT(object->size == 0, 340 ("largepage phys obj %p not initialized bit size %#jx > 0", 341 object, (uintmax_t)object->size)); 342 } 343 } 344 345 static const struct phys_pager_ops shm_largepage_phys_ops = { 346 .phys_pg_populate = shm_largepage_phys_populate, 347 .phys_pg_haspage = shm_largepage_phys_haspage, 348 .phys_pg_ctor = shm_largepage_phys_ctor, 349 .phys_pg_dtor = shm_largepage_phys_dtor, 350 }; 351 352 bool 353 shm_largepage(struct shmfd *shmfd) 354 { 355 return (shmfd->shm_object->type == OBJT_PHYS); 356 } 357 358 static void 359 shm_pager_freespace(vm_object_t obj, vm_pindex_t start, vm_size_t size) 360 { 361 struct shmfd *shm; 362 vm_size_t c; 363 364 swap_pager_freespace(obj, start, size, &c); 365 if (c == 0) 366 return; 367 368 shm = obj->un_pager.swp.swp_priv; 369 if (shm == NULL) 370 return; 371 KASSERT(shm->shm_pages >= c, 372 ("shm %p pages %jd free %jd", shm, 373 (uintmax_t)shm->shm_pages, (uintmax_t)c)); 374 shm->shm_pages -= c; 375 } 376 377 static void 378 shm_page_inserted(vm_object_t obj, vm_page_t m) 379 { 380 struct shmfd *shm; 381 382 shm = obj->un_pager.swp.swp_priv; 383 if (shm == NULL) 384 return; 385 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) 386 shm->shm_pages += 1; 387 } 388 389 static void 390 shm_page_removed(vm_object_t obj, vm_page_t m) 391 { 392 struct shmfd *shm; 393 394 shm = obj->un_pager.swp.swp_priv; 395 if (shm == NULL) 396 return; 397 if (!vm_pager_has_page(obj, m->pindex, NULL, NULL)) { 398 KASSERT(shm->shm_pages >= 1, 399 ("shm %p pages %jd free 1", shm, 400 (uintmax_t)shm->shm_pages)); 401 shm->shm_pages -= 1; 402 } 403 } 404 405 static struct pagerops shm_swap_pager_ops = { 406 .pgo_kvme_type = KVME_TYPE_SWAP, 407 .pgo_freespace = shm_pager_freespace, 408 .pgo_page_inserted = shm_page_inserted, 409 .pgo_page_removed = shm_page_removed, 410 }; 411 static int shmfd_pager_type = -1; 412 413 static int 414 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 415 { 416 struct shmfd *shmfd; 417 off_t foffset; 418 int error; 419 420 shmfd = fp->f_data; 421 foffset = foffset_lock(fp, 0); 422 error = 0; 423 switch (whence) { 424 case L_INCR: 425 if (foffset < 0 || 426 (offset > 0 && foffset > OFF_MAX - offset)) { 427 error = EOVERFLOW; 428 break; 429 } 430 offset += foffset; 431 break; 432 case L_XTND: 433 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 434 error = EOVERFLOW; 435 break; 436 } 437 offset += shmfd->shm_size; 438 break; 439 case L_SET: 440 break; 441 default: 442 error = EINVAL; 443 } 444 if (error == 0) { 445 if (offset < 0 || offset > shmfd->shm_size) 446 error = EINVAL; 447 else 448 td->td_uretoff.tdu_off = offset; 449 } 450 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 451 return (error); 452 } 453 454 static int 455 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 456 int flags, struct thread *td) 457 { 458 struct shmfd *shmfd; 459 void *rl_cookie; 460 int error; 461 462 shmfd = fp->f_data; 463 #ifdef MAC 464 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 465 if (error) 466 return (error); 467 #endif 468 foffset_lock_uio(fp, uio, flags); 469 rl_cookie = shm_rangelock_rlock(shmfd, uio->uio_offset, 470 uio->uio_offset + uio->uio_resid); 471 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 472 shm_rangelock_unlock(shmfd, rl_cookie); 473 foffset_unlock_uio(fp, uio, flags); 474 return (error); 475 } 476 477 static int 478 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 479 int flags, struct thread *td) 480 { 481 struct shmfd *shmfd; 482 void *rl_cookie; 483 int error; 484 off_t newsize; 485 486 KASSERT((flags & FOF_OFFSET) == 0 || uio->uio_offset >= 0, 487 ("%s: negative offset", __func__)); 488 489 shmfd = fp->f_data; 490 #ifdef MAC 491 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 492 if (error) 493 return (error); 494 #endif 495 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 496 return (EINVAL); 497 foffset_lock_uio(fp, uio, flags); 498 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 499 /* 500 * Overflow is only an error if we're supposed to expand on 501 * write. Otherwise, we'll just truncate the write to the 502 * size of the file, which can only grow up to OFF_MAX. 503 */ 504 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 505 foffset_unlock_uio(fp, uio, flags); 506 return (EFBIG); 507 } 508 509 newsize = atomic_load_64(&shmfd->shm_size); 510 } else { 511 newsize = uio->uio_offset + uio->uio_resid; 512 } 513 if ((flags & FOF_OFFSET) == 0) 514 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 515 else 516 rl_cookie = shm_rangelock_wlock(shmfd, uio->uio_offset, 517 MAX(newsize, uio->uio_offset)); 518 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 519 error = EPERM; 520 } else { 521 error = 0; 522 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 523 newsize > shmfd->shm_size) { 524 error = shm_dotruncate_cookie(shmfd, newsize, 525 rl_cookie); 526 } 527 if (error == 0) 528 error = uiomove_object(shmfd->shm_object, 529 shmfd->shm_size, uio); 530 } 531 shm_rangelock_unlock(shmfd, rl_cookie); 532 foffset_unlock_uio(fp, uio, flags); 533 return (error); 534 } 535 536 static int 537 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 538 struct thread *td) 539 { 540 struct shmfd *shmfd; 541 #ifdef MAC 542 int error; 543 #endif 544 545 shmfd = fp->f_data; 546 #ifdef MAC 547 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 548 if (error) 549 return (error); 550 #endif 551 return (shm_dotruncate(shmfd, length)); 552 } 553 554 int 555 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 556 struct thread *td) 557 { 558 struct shmfd *shmfd; 559 struct shm_largepage_conf *conf; 560 void *rl_cookie; 561 562 shmfd = fp->f_data; 563 switch (com) { 564 case FIONBIO: 565 case FIOASYNC: 566 /* 567 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 568 * just like it would on an unlinked regular file 569 */ 570 return (0); 571 case FIOSSHMLPGCNF: 572 if (!shm_largepage(shmfd)) 573 return (ENOTTY); 574 conf = data; 575 if (shmfd->shm_lp_psind != 0 && 576 conf->psind != shmfd->shm_lp_psind) 577 return (EINVAL); 578 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 579 pagesizes[conf->psind] == 0) 580 return (EINVAL); 581 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 582 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 583 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 584 return (EINVAL); 585 586 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 587 shmfd->shm_lp_psind = conf->psind; 588 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 589 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 590 shm_rangelock_unlock(shmfd, rl_cookie); 591 return (0); 592 case FIOGSHMLPGCNF: 593 if (!shm_largepage(shmfd)) 594 return (ENOTTY); 595 conf = data; 596 rl_cookie = shm_rangelock_rlock(shmfd, 0, OFF_MAX); 597 conf->psind = shmfd->shm_lp_psind; 598 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 599 shm_rangelock_unlock(shmfd, rl_cookie); 600 return (0); 601 default: 602 return (ENOTTY); 603 } 604 } 605 606 static int 607 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred) 608 { 609 struct shmfd *shmfd; 610 #ifdef MAC 611 int error; 612 #endif 613 614 shmfd = fp->f_data; 615 616 #ifdef MAC 617 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 618 if (error) 619 return (error); 620 #endif 621 622 /* 623 * Attempt to return sanish values for fstat() on a memory file 624 * descriptor. 625 */ 626 bzero(sb, sizeof(*sb)); 627 sb->st_blksize = PAGE_SIZE; 628 sb->st_size = shmfd->shm_size; 629 mtx_lock(&shm_timestamp_lock); 630 sb->st_atim = shmfd->shm_atime; 631 sb->st_ctim = shmfd->shm_ctime; 632 sb->st_mtim = shmfd->shm_mtime; 633 sb->st_birthtim = shmfd->shm_birthtime; 634 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 635 sb->st_uid = shmfd->shm_uid; 636 sb->st_gid = shmfd->shm_gid; 637 mtx_unlock(&shm_timestamp_lock); 638 sb->st_dev = shm_dev_ino; 639 sb->st_ino = shmfd->shm_ino; 640 sb->st_nlink = shmfd->shm_object->ref_count; 641 if (shm_largepage(shmfd)) { 642 sb->st_blocks = shmfd->shm_object->size / 643 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 644 } else { 645 sb->st_blocks = shmfd->shm_pages; 646 } 647 648 return (0); 649 } 650 651 static int 652 shm_close(struct file *fp, struct thread *td) 653 { 654 struct shmfd *shmfd; 655 656 shmfd = fp->f_data; 657 fp->f_data = NULL; 658 shm_drop(shmfd); 659 660 return (0); 661 } 662 663 static int 664 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 665 int error; 666 char *path; 667 const char *pr_path; 668 size_t pr_pathlen; 669 670 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 671 pr_path = td->td_ucred->cr_prison->pr_path; 672 673 /* Construct a full pathname for jailed callers. */ 674 pr_pathlen = strcmp(pr_path, "/") == 675 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 676 error = copyinstr(userpath_in, path + pr_pathlen, 677 MAXPATHLEN - pr_pathlen, NULL); 678 if (error != 0) 679 goto out; 680 681 #ifdef KTRACE 682 if (KTRPOINT(curthread, KTR_NAMEI)) 683 ktrnamei(path); 684 #endif 685 686 /* Require paths to start with a '/' character. */ 687 if (path[pr_pathlen] != '/') { 688 error = EINVAL; 689 goto out; 690 } 691 692 *path_out = path; 693 694 out: 695 if (error != 0) 696 free(path, M_SHMFD); 697 698 return (error); 699 } 700 701 static int 702 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base, 703 int end) 704 { 705 int error; 706 707 error = vm_page_grab_zero_partial(object, idx, base, end); 708 if (error == EIO) 709 VM_OBJECT_WUNLOCK(object); 710 return (error); 711 } 712 713 static int 714 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 715 { 716 vm_object_t object; 717 vm_pindex_t nobjsize; 718 vm_ooffset_t delta; 719 int base, error; 720 721 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 722 object = shmfd->shm_object; 723 VM_OBJECT_ASSERT_WLOCKED(object); 724 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 725 if (length == shmfd->shm_size) 726 return (0); 727 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 728 729 /* Are we shrinking? If so, trim the end. */ 730 if (length < shmfd->shm_size) { 731 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 732 return (EPERM); 733 734 /* 735 * Disallow any requests to shrink the size if this 736 * object is mapped into the kernel. 737 */ 738 if (shmfd->shm_kmappings > 0) 739 return (EBUSY); 740 741 /* 742 * Zero the truncated part of the last page. 743 */ 744 base = length & PAGE_MASK; 745 if (base != 0) { 746 error = shm_partial_page_invalidate(object, 747 OFF_TO_IDX(length), base, PAGE_SIZE); 748 if (error) 749 return (error); 750 } 751 delta = IDX_TO_OFF(object->size - nobjsize); 752 753 if (nobjsize < object->size) 754 vm_object_page_remove(object, nobjsize, object->size, 755 0); 756 757 /* Free the swap accounted for shm */ 758 swap_release_by_cred(delta, object->cred); 759 object->charge -= delta; 760 } else { 761 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 762 return (EPERM); 763 764 /* Try to reserve additional swap space. */ 765 delta = IDX_TO_OFF(nobjsize - object->size); 766 if (!swap_reserve_by_cred(delta, object->cred)) 767 return (ENOMEM); 768 object->charge += delta; 769 } 770 shmfd->shm_size = length; 771 mtx_lock(&shm_timestamp_lock); 772 vfs_timestamp(&shmfd->shm_ctime); 773 shmfd->shm_mtime = shmfd->shm_ctime; 774 mtx_unlock(&shm_timestamp_lock); 775 object->size = nobjsize; 776 return (0); 777 } 778 779 static int 780 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 781 { 782 vm_object_t object; 783 vm_page_t m; 784 vm_pindex_t newobjsz; 785 vm_pindex_t oldobjsz __unused; 786 int aflags, error, i, psind, try; 787 788 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 789 object = shmfd->shm_object; 790 VM_OBJECT_ASSERT_WLOCKED(object); 791 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 792 793 oldobjsz = object->size; 794 newobjsz = OFF_TO_IDX(length); 795 if (length == shmfd->shm_size) 796 return (0); 797 psind = shmfd->shm_lp_psind; 798 if (psind == 0 && length != 0) 799 return (EINVAL); 800 if ((length & (pagesizes[psind] - 1)) != 0) 801 return (EINVAL); 802 803 if (length < shmfd->shm_size) { 804 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 805 return (EPERM); 806 if (shmfd->shm_kmappings > 0) 807 return (EBUSY); 808 return (ENOTSUP); /* Pages are unmanaged. */ 809 #if 0 810 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 811 object->size = newobjsz; 812 shmfd->shm_size = length; 813 return (0); 814 #endif 815 } 816 817 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 818 return (EPERM); 819 820 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 821 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 822 aflags |= VM_ALLOC_WAITFAIL; 823 try = 0; 824 825 /* 826 * Extend shmfd and object, keeping all already fully 827 * allocated large pages intact even on error, because dropped 828 * object lock might allowed mapping of them. 829 */ 830 while (object->size < newobjsz) { 831 m = vm_page_alloc_contig(object, object->size, aflags, 832 pagesizes[psind] / PAGE_SIZE, 0, ~0, 833 pagesizes[psind], 0, 834 VM_MEMATTR_DEFAULT); 835 if (m == NULL) { 836 VM_OBJECT_WUNLOCK(object); 837 if (shmfd->shm_lp_alloc_policy == 838 SHM_LARGEPAGE_ALLOC_NOWAIT || 839 (shmfd->shm_lp_alloc_policy == 840 SHM_LARGEPAGE_ALLOC_DEFAULT && 841 try >= largepage_reclaim_tries)) { 842 VM_OBJECT_WLOCK(object); 843 return (ENOMEM); 844 } 845 error = vm_page_reclaim_contig(aflags, 846 pagesizes[psind] / PAGE_SIZE, 0, ~0, 847 pagesizes[psind], 0); 848 if (error == ENOMEM) 849 error = vm_wait_intr(object); 850 if (error != 0) { 851 VM_OBJECT_WLOCK(object); 852 return (error); 853 } 854 try++; 855 VM_OBJECT_WLOCK(object); 856 continue; 857 } 858 try = 0; 859 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 860 if ((m[i].flags & PG_ZERO) == 0) 861 pmap_zero_page(&m[i]); 862 vm_page_valid(&m[i]); 863 vm_page_xunbusy(&m[i]); 864 } 865 object->size += OFF_TO_IDX(pagesizes[psind]); 866 shmfd->shm_size += pagesizes[psind]; 867 atomic_add_long(&count_largepages[psind], 1); 868 vm_wire_add(atop(pagesizes[psind])); 869 } 870 return (0); 871 } 872 873 static int 874 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 875 { 876 int error; 877 878 VM_OBJECT_WLOCK(shmfd->shm_object); 879 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 880 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 881 rl_cookie); 882 VM_OBJECT_WUNLOCK(shmfd->shm_object); 883 return (error); 884 } 885 886 int 887 shm_dotruncate(struct shmfd *shmfd, off_t length) 888 { 889 void *rl_cookie; 890 int error; 891 892 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 893 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 894 shm_rangelock_unlock(shmfd, rl_cookie); 895 return (error); 896 } 897 898 /* 899 * shmfd object management including creation and reference counting 900 * routines. 901 */ 902 struct shmfd * 903 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 904 { 905 struct shmfd *shmfd; 906 vm_object_t obj; 907 908 if (largepage) { 909 obj = phys_pager_allocate(NULL, &shm_largepage_phys_ops, 910 NULL, 0, VM_PROT_DEFAULT, 0, ucred); 911 } else { 912 obj = vm_pager_allocate(shmfd_pager_type, NULL, 0, 913 VM_PROT_DEFAULT, 0, ucred); 914 } 915 if (obj == NULL) { 916 /* 917 * swap reservation limits can cause object allocation 918 * to fail. 919 */ 920 return (NULL); 921 } 922 923 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 924 shmfd->shm_uid = ucred->cr_uid; 925 shmfd->shm_gid = ucred->cr_gid; 926 shmfd->shm_mode = mode; 927 if (largepage) { 928 obj->un_pager.phys.phys_priv = shmfd; 929 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 930 } else { 931 obj->un_pager.swp.swp_priv = shmfd; 932 } 933 934 VM_OBJECT_WLOCK(obj); 935 vm_object_set_flag(obj, OBJ_POSIXSHM); 936 VM_OBJECT_WUNLOCK(obj); 937 shmfd->shm_object = obj; 938 vfs_timestamp(&shmfd->shm_birthtime); 939 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 940 shmfd->shm_birthtime; 941 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 942 refcount_init(&shmfd->shm_refs, 1); 943 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 944 rangelock_init(&shmfd->shm_rl); 945 #ifdef MAC 946 mac_posixshm_init(shmfd); 947 mac_posixshm_create(ucred, shmfd); 948 #endif 949 950 return (shmfd); 951 } 952 953 struct shmfd * 954 shm_hold(struct shmfd *shmfd) 955 { 956 957 refcount_acquire(&shmfd->shm_refs); 958 return (shmfd); 959 } 960 961 void 962 shm_drop(struct shmfd *shmfd) 963 { 964 vm_object_t obj; 965 966 if (refcount_release(&shmfd->shm_refs)) { 967 #ifdef MAC 968 mac_posixshm_destroy(shmfd); 969 #endif 970 rangelock_destroy(&shmfd->shm_rl); 971 mtx_destroy(&shmfd->shm_mtx); 972 obj = shmfd->shm_object; 973 VM_OBJECT_WLOCK(obj); 974 if (shm_largepage(shmfd)) 975 obj->un_pager.phys.phys_priv = NULL; 976 else 977 obj->un_pager.swp.swp_priv = NULL; 978 VM_OBJECT_WUNLOCK(obj); 979 vm_object_deallocate(obj); 980 free(shmfd, M_SHMFD); 981 } 982 } 983 984 /* 985 * Determine if the credentials have sufficient permissions for a 986 * specified combination of FREAD and FWRITE. 987 */ 988 int 989 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 990 { 991 accmode_t accmode; 992 int error; 993 994 accmode = 0; 995 if (flags & FREAD) 996 accmode |= VREAD; 997 if (flags & FWRITE) 998 accmode |= VWRITE; 999 mtx_lock(&shm_timestamp_lock); 1000 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1001 accmode, ucred); 1002 mtx_unlock(&shm_timestamp_lock); 1003 return (error); 1004 } 1005 1006 static void 1007 shm_init(void *arg) 1008 { 1009 char name[32]; 1010 int i; 1011 1012 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 1013 sx_init(&shm_dict_lock, "shm dictionary"); 1014 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 1015 new_unrhdr64(&shm_ino_unr, 1); 1016 shm_dev_ino = devfs_alloc_cdp_inode(); 1017 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 1018 shmfd_pager_type = vm_pager_alloc_dyn_type(&shm_swap_pager_ops, 1019 OBJT_SWAP); 1020 MPASS(shmfd_pager_type != -1); 1021 1022 for (i = 1; i < MAXPAGESIZES; i++) { 1023 if (pagesizes[i] == 0) 1024 break; 1025 #define M (1024 * 1024) 1026 #define G (1024 * M) 1027 if (pagesizes[i] >= G) 1028 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 1029 else if (pagesizes[i] >= M) 1030 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 1031 else 1032 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 1033 #undef G 1034 #undef M 1035 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 1036 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 1037 "number of non-transient largepages allocated"); 1038 } 1039 } 1040 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 1041 1042 /* 1043 * Remove all shared memory objects that belong to a prison. 1044 */ 1045 void 1046 shm_remove_prison(struct prison *pr) 1047 { 1048 struct shm_mapping *shmm, *tshmm; 1049 u_long i; 1050 1051 sx_xlock(&shm_dict_lock); 1052 for (i = 0; i < shm_hash + 1; i++) { 1053 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) { 1054 if (shmm->sm_shmfd->shm_object->cred && 1055 shmm->sm_shmfd->shm_object->cred->cr_prison == pr) 1056 shm_doremove(shmm); 1057 } 1058 } 1059 sx_xunlock(&shm_dict_lock); 1060 } 1061 1062 /* 1063 * Dictionary management. We maintain an in-kernel dictionary to map 1064 * paths to shmfd objects. We use the FNV hash on the path to store 1065 * the mappings in a hash table. 1066 */ 1067 static struct shmfd * 1068 shm_lookup(char *path, Fnv32_t fnv) 1069 { 1070 struct shm_mapping *map; 1071 1072 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1073 if (map->sm_fnv != fnv) 1074 continue; 1075 if (strcmp(map->sm_path, path) == 0) 1076 return (map->sm_shmfd); 1077 } 1078 1079 return (NULL); 1080 } 1081 1082 static void 1083 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 1084 { 1085 struct shm_mapping *map; 1086 1087 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 1088 map->sm_path = path; 1089 map->sm_fnv = fnv; 1090 map->sm_shmfd = shm_hold(shmfd); 1091 shmfd->shm_path = path; 1092 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 1093 } 1094 1095 static int 1096 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1097 { 1098 struct shm_mapping *map; 1099 int error; 1100 1101 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1102 if (map->sm_fnv != fnv) 1103 continue; 1104 if (strcmp(map->sm_path, path) == 0) { 1105 #ifdef MAC 1106 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1107 if (error) 1108 return (error); 1109 #endif 1110 error = shm_access(map->sm_shmfd, ucred, 1111 FREAD | FWRITE); 1112 if (error) 1113 return (error); 1114 shm_doremove(map); 1115 return (0); 1116 } 1117 } 1118 1119 return (ENOENT); 1120 } 1121 1122 static void 1123 shm_doremove(struct shm_mapping *map) 1124 { 1125 map->sm_shmfd->shm_path = NULL; 1126 LIST_REMOVE(map, sm_link); 1127 shm_drop(map->sm_shmfd); 1128 free(map->sm_path, M_SHMFD); 1129 free(map, M_SHMFD); 1130 } 1131 1132 int 1133 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1134 int shmflags, struct filecaps *fcaps, const char *name __unused) 1135 { 1136 struct pwddesc *pdp; 1137 struct shmfd *shmfd; 1138 struct file *fp; 1139 char *path; 1140 void *rl_cookie; 1141 Fnv32_t fnv; 1142 mode_t cmode; 1143 int error, fd, initial_seals; 1144 bool largepage; 1145 1146 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1147 SHM_LARGEPAGE)) != 0) 1148 return (EINVAL); 1149 1150 initial_seals = F_SEAL_SEAL; 1151 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1152 initial_seals &= ~F_SEAL_SEAL; 1153 1154 AUDIT_ARG_FFLAGS(flags); 1155 AUDIT_ARG_MODE(mode); 1156 1157 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1158 return (EINVAL); 1159 1160 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1161 return (EINVAL); 1162 1163 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1164 if (largepage && !PMAP_HAS_LARGEPAGES) 1165 return (ENOTTY); 1166 1167 /* 1168 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1169 * If the decision is made later to allow additional seals, care must be 1170 * taken below to ensure that the seals are properly set if the shmfd 1171 * already existed -- this currently assumes that only F_SEAL_SEAL can 1172 * be set and doesn't take further precautions to ensure the validity of 1173 * the seals being added with respect to current mappings. 1174 */ 1175 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1176 return (EINVAL); 1177 1178 if (userpath != SHM_ANON) { 1179 error = shm_copyin_path(td, userpath, &path); 1180 if (error != 0) 1181 return (error); 1182 1183 #ifdef CAPABILITY_MODE 1184 /* 1185 * shm_open(2) is only allowed for anonymous objects. 1186 */ 1187 if (CAP_TRACING(td)) 1188 ktrcapfail(CAPFAIL_NAMEI, path); 1189 if (IN_CAPABILITY_MODE(td)) { 1190 error = ECAPMODE; 1191 goto outnofp; 1192 } 1193 #endif 1194 1195 AUDIT_ARG_UPATH1_CANON(path); 1196 } else { 1197 path = NULL; 1198 } 1199 1200 pdp = td->td_proc->p_pd; 1201 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1202 1203 /* 1204 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1205 * by POSIX. We allow it to be unset here so that an in-kernel 1206 * interface may be written as a thin layer around shm, optionally not 1207 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1208 * in sys_shm_open() to keep this implementation compliant. 1209 */ 1210 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1211 if (error != 0) 1212 goto outnofp; 1213 1214 /* A SHM_ANON path pointer creates an anonymous object. */ 1215 if (userpath == SHM_ANON) { 1216 /* A read-only anonymous object is pointless. */ 1217 if ((flags & O_ACCMODE) == O_RDONLY) { 1218 error = EINVAL; 1219 goto out; 1220 } 1221 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1222 if (shmfd == NULL) { 1223 error = ENOMEM; 1224 goto out; 1225 } 1226 shmfd->shm_seals = initial_seals; 1227 shmfd->shm_flags = shmflags; 1228 } else { 1229 fnv = fnv_32_str(path, FNV1_32_INIT); 1230 sx_xlock(&shm_dict_lock); 1231 shmfd = shm_lookup(path, fnv); 1232 if (shmfd == NULL) { 1233 /* Object does not yet exist, create it if requested. */ 1234 if (flags & O_CREAT) { 1235 #ifdef MAC 1236 error = mac_posixshm_check_create(td->td_ucred, 1237 path); 1238 if (error == 0) { 1239 #endif 1240 shmfd = shm_alloc(td->td_ucred, cmode, 1241 largepage); 1242 if (shmfd == NULL) { 1243 error = ENOMEM; 1244 } else { 1245 shmfd->shm_seals = 1246 initial_seals; 1247 shmfd->shm_flags = shmflags; 1248 shm_insert(path, fnv, shmfd); 1249 path = NULL; 1250 } 1251 #ifdef MAC 1252 } 1253 #endif 1254 } else { 1255 error = ENOENT; 1256 } 1257 } else { 1258 /* 1259 * Object already exists, obtain a new reference if 1260 * requested and permitted. 1261 */ 1262 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1263 1264 /* 1265 * kern_shm_open() likely shouldn't ever error out on 1266 * trying to set a seal that already exists, unlike 1267 * F_ADD_SEALS. This would break terribly as 1268 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1269 * historical behavior where the underlying file could 1270 * not be sealed. 1271 */ 1272 initial_seals &= ~shmfd->shm_seals; 1273 1274 /* 1275 * initial_seals can't set additional seals if we've 1276 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1277 * then we've already removed that one from 1278 * initial_seals. This is currently redundant as we 1279 * only allow setting F_SEAL_SEAL at creation time, but 1280 * it's cheap to check and decreases the effort required 1281 * to allow additional seals. 1282 */ 1283 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1284 initial_seals != 0) 1285 error = EPERM; 1286 else if ((flags & (O_CREAT | O_EXCL)) == 1287 (O_CREAT | O_EXCL)) 1288 error = EEXIST; 1289 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1290 error = EINVAL; 1291 else { 1292 #ifdef MAC 1293 error = mac_posixshm_check_open(td->td_ucred, 1294 shmfd, FFLAGS(flags & O_ACCMODE)); 1295 if (error == 0) 1296 #endif 1297 error = shm_access(shmfd, td->td_ucred, 1298 FFLAGS(flags & O_ACCMODE)); 1299 } 1300 1301 /* 1302 * Truncate the file back to zero length if 1303 * O_TRUNC was specified and the object was 1304 * opened with read/write. 1305 */ 1306 if (error == 0 && 1307 (flags & (O_ACCMODE | O_TRUNC)) == 1308 (O_RDWR | O_TRUNC)) { 1309 VM_OBJECT_WLOCK(shmfd->shm_object); 1310 #ifdef MAC 1311 error = mac_posixshm_check_truncate( 1312 td->td_ucred, fp->f_cred, shmfd); 1313 if (error == 0) 1314 #endif 1315 error = shm_dotruncate_locked(shmfd, 0, 1316 rl_cookie); 1317 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1318 } 1319 if (error == 0) { 1320 /* 1321 * Currently we only allow F_SEAL_SEAL to be 1322 * set initially. As noted above, this would 1323 * need to be reworked should that change. 1324 */ 1325 shmfd->shm_seals |= initial_seals; 1326 shm_hold(shmfd); 1327 } 1328 shm_rangelock_unlock(shmfd, rl_cookie); 1329 } 1330 sx_xunlock(&shm_dict_lock); 1331 1332 if (error != 0) 1333 goto out; 1334 } 1335 1336 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1337 1338 td->td_retval[0] = fd; 1339 fdrop(fp, td); 1340 free(path, M_SHMFD); 1341 1342 return (0); 1343 1344 out: 1345 fdclose(td, fp, fd); 1346 fdrop(fp, td); 1347 outnofp: 1348 free(path, M_SHMFD); 1349 1350 return (error); 1351 } 1352 1353 /* System calls. */ 1354 #ifdef COMPAT_FREEBSD12 1355 int 1356 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1357 { 1358 1359 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1360 uap->mode, NULL)); 1361 } 1362 #endif 1363 1364 int 1365 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1366 { 1367 char *path; 1368 Fnv32_t fnv; 1369 int error; 1370 1371 error = shm_copyin_path(td, uap->path, &path); 1372 if (error != 0) 1373 return (error); 1374 1375 AUDIT_ARG_UPATH1_CANON(path); 1376 fnv = fnv_32_str(path, FNV1_32_INIT); 1377 sx_xlock(&shm_dict_lock); 1378 error = shm_remove(path, fnv, td->td_ucred); 1379 sx_xunlock(&shm_dict_lock); 1380 free(path, M_SHMFD); 1381 1382 return (error); 1383 } 1384 1385 int 1386 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1387 { 1388 char *path_from = NULL, *path_to = NULL; 1389 Fnv32_t fnv_from, fnv_to; 1390 struct shmfd *fd_from; 1391 struct shmfd *fd_to; 1392 int error; 1393 int flags; 1394 1395 flags = uap->flags; 1396 AUDIT_ARG_FFLAGS(flags); 1397 1398 /* 1399 * Make sure the user passed only valid flags. 1400 * If you add a new flag, please add a new term here. 1401 */ 1402 if ((flags & ~( 1403 SHM_RENAME_NOREPLACE | 1404 SHM_RENAME_EXCHANGE 1405 )) != 0) { 1406 error = EINVAL; 1407 goto out; 1408 } 1409 1410 /* 1411 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1412 * force the user to choose one or the other. 1413 */ 1414 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1415 (flags & SHM_RENAME_EXCHANGE) != 0) { 1416 error = EINVAL; 1417 goto out; 1418 } 1419 1420 /* Renaming to or from anonymous makes no sense */ 1421 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1422 error = EINVAL; 1423 goto out; 1424 } 1425 1426 error = shm_copyin_path(td, uap->path_from, &path_from); 1427 if (error != 0) 1428 goto out; 1429 1430 error = shm_copyin_path(td, uap->path_to, &path_to); 1431 if (error != 0) 1432 goto out; 1433 1434 AUDIT_ARG_UPATH1_CANON(path_from); 1435 AUDIT_ARG_UPATH2_CANON(path_to); 1436 1437 /* Rename with from/to equal is a no-op */ 1438 if (strcmp(path_from, path_to) == 0) 1439 goto out; 1440 1441 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1442 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1443 1444 sx_xlock(&shm_dict_lock); 1445 1446 fd_from = shm_lookup(path_from, fnv_from); 1447 if (fd_from == NULL) { 1448 error = ENOENT; 1449 goto out_locked; 1450 } 1451 1452 fd_to = shm_lookup(path_to, fnv_to); 1453 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1454 error = EEXIST; 1455 goto out_locked; 1456 } 1457 1458 /* 1459 * Unconditionally prevents shm_remove from invalidating the 'from' 1460 * shm's state. 1461 */ 1462 shm_hold(fd_from); 1463 error = shm_remove(path_from, fnv_from, td->td_ucred); 1464 1465 /* 1466 * One of my assumptions failed if ENOENT (e.g. locking didn't 1467 * protect us) 1468 */ 1469 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1470 path_from)); 1471 if (error != 0) { 1472 shm_drop(fd_from); 1473 goto out_locked; 1474 } 1475 1476 /* 1477 * If we are exchanging, we need to ensure the shm_remove below 1478 * doesn't invalidate the dest shm's state. 1479 */ 1480 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1481 shm_hold(fd_to); 1482 1483 /* 1484 * NOTE: if path_to is not already in the hash, c'est la vie; 1485 * it simply means we have nothing already at path_to to unlink. 1486 * That is the ENOENT case. 1487 * 1488 * If we somehow don't have access to unlink this guy, but 1489 * did for the shm at path_from, then relink the shm to path_from 1490 * and abort with EACCES. 1491 * 1492 * All other errors: that is weird; let's relink and abort the 1493 * operation. 1494 */ 1495 error = shm_remove(path_to, fnv_to, td->td_ucred); 1496 if (error != 0 && error != ENOENT) { 1497 shm_insert(path_from, fnv_from, fd_from); 1498 shm_drop(fd_from); 1499 /* Don't free path_from now, since the hash references it */ 1500 path_from = NULL; 1501 goto out_locked; 1502 } 1503 1504 error = 0; 1505 1506 shm_insert(path_to, fnv_to, fd_from); 1507 1508 /* Don't free path_to now, since the hash references it */ 1509 path_to = NULL; 1510 1511 /* We kept a ref when we removed, and incremented again in insert */ 1512 shm_drop(fd_from); 1513 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1514 fd_from->shm_refs)); 1515 1516 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1517 shm_insert(path_from, fnv_from, fd_to); 1518 path_from = NULL; 1519 shm_drop(fd_to); 1520 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1521 fd_to->shm_refs)); 1522 } 1523 1524 out_locked: 1525 sx_xunlock(&shm_dict_lock); 1526 1527 out: 1528 free(path_from, M_SHMFD); 1529 free(path_to, M_SHMFD); 1530 return (error); 1531 } 1532 1533 static int 1534 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1535 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1536 vm_ooffset_t foff, struct thread *td) 1537 { 1538 struct vmspace *vms; 1539 vm_map_entry_t next_entry, prev_entry; 1540 vm_offset_t align, mask, maxaddr; 1541 int docow, error, rv, try; 1542 bool curmap; 1543 1544 if (shmfd->shm_lp_psind == 0) 1545 return (EINVAL); 1546 1547 /* MAP_PRIVATE is disabled */ 1548 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1549 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0) 1550 return (EINVAL); 1551 1552 vms = td->td_proc->p_vmspace; 1553 curmap = map == &vms->vm_map; 1554 if (curmap) { 1555 error = kern_mmap_racct_check(td, map, size); 1556 if (error != 0) 1557 return (error); 1558 } 1559 1560 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1561 docow |= MAP_INHERIT_SHARE; 1562 if ((flags & MAP_NOCORE) != 0) 1563 docow |= MAP_DISABLE_COREDUMP; 1564 1565 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1566 if ((foff & mask) != 0) 1567 return (EINVAL); 1568 maxaddr = vm_map_max(map); 1569 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1570 maxaddr = MAP_32BIT_MAX_ADDR; 1571 if (size == 0 || (size & mask) != 0 || 1572 (*addr != 0 && ((*addr & mask) != 0 || 1573 *addr + size < *addr || *addr + size > maxaddr))) 1574 return (EINVAL); 1575 1576 align = flags & MAP_ALIGNMENT_MASK; 1577 if (align == 0) { 1578 align = pagesizes[shmfd->shm_lp_psind]; 1579 } else if (align == MAP_ALIGNED_SUPER) { 1580 /* 1581 * MAP_ALIGNED_SUPER is only supported on superpage sizes, 1582 * i.e., [1, VM_NRESERVLEVEL]. shmfd->shm_lp_psind < 1 is 1583 * handled above. 1584 */ 1585 if ( 1586 #if VM_NRESERVLEVEL > 0 1587 shmfd->shm_lp_psind > VM_NRESERVLEVEL 1588 #else 1589 shmfd->shm_lp_psind > 1 1590 #endif 1591 ) 1592 return (EINVAL); 1593 align = pagesizes[shmfd->shm_lp_psind]; 1594 } else { 1595 align >>= MAP_ALIGNMENT_SHIFT; 1596 align = 1ULL << align; 1597 /* Also handles overflow. */ 1598 if (align < pagesizes[shmfd->shm_lp_psind]) 1599 return (EINVAL); 1600 } 1601 1602 vm_map_lock(map); 1603 if ((flags & MAP_FIXED) == 0) { 1604 try = 1; 1605 if (curmap && (*addr == 0 || 1606 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1607 *addr < round_page((vm_offset_t)vms->vm_daddr + 1608 lim_max(td, RLIMIT_DATA))))) { 1609 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1610 lim_max(td, RLIMIT_DATA), 1611 pagesizes[shmfd->shm_lp_psind]); 1612 } 1613 again: 1614 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1615 if (rv != KERN_SUCCESS) { 1616 if (try == 1) { 1617 try = 2; 1618 *addr = vm_map_min(map); 1619 if ((*addr & mask) != 0) 1620 *addr = (*addr + mask) & mask; 1621 goto again; 1622 } 1623 goto fail1; 1624 } 1625 } else if ((flags & MAP_EXCL) == 0) { 1626 rv = vm_map_delete(map, *addr, *addr + size); 1627 if (rv != KERN_SUCCESS) 1628 goto fail1; 1629 } else { 1630 error = ENOSPC; 1631 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1632 goto fail; 1633 next_entry = vm_map_entry_succ(prev_entry); 1634 if (next_entry->start < *addr + size) 1635 goto fail; 1636 } 1637 1638 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1639 prot, max_prot, docow); 1640 fail1: 1641 error = vm_mmap_to_errno(rv); 1642 fail: 1643 vm_map_unlock(map); 1644 return (error); 1645 } 1646 1647 static int 1648 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1649 vm_prot_t prot, vm_prot_t max_maxprot, int flags, 1650 vm_ooffset_t foff, struct thread *td) 1651 { 1652 struct shmfd *shmfd; 1653 vm_prot_t maxprot; 1654 int error; 1655 bool writecnt; 1656 void *rl_cookie; 1657 1658 shmfd = fp->f_data; 1659 maxprot = VM_PROT_NONE; 1660 1661 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize); 1662 /* FREAD should always be set. */ 1663 if ((fp->f_flag & FREAD) != 0) 1664 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1665 1666 /* 1667 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1668 * mapping with a write seal applied. Private mappings are always 1669 * writeable. 1670 */ 1671 if ((flags & MAP_SHARED) == 0) { 1672 if ((max_maxprot & VM_PROT_WRITE) != 0) 1673 maxprot |= VM_PROT_WRITE; 1674 writecnt = false; 1675 } else { 1676 if ((fp->f_flag & FWRITE) != 0 && 1677 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1678 maxprot |= VM_PROT_WRITE; 1679 1680 /* 1681 * Any mappings from a writable descriptor may be upgraded to 1682 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1683 * applied between the open and subsequent mmap(2). We want to 1684 * reject application of a write seal as long as any such 1685 * mapping exists so that the seal cannot be trivially bypassed. 1686 */ 1687 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1688 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1689 error = EACCES; 1690 goto out; 1691 } 1692 } 1693 maxprot &= max_maxprot; 1694 1695 /* See comment in vn_mmap(). */ 1696 if ( 1697 #ifdef _LP64 1698 objsize > OFF_MAX || 1699 #endif 1700 foff > OFF_MAX - objsize) { 1701 error = EINVAL; 1702 goto out; 1703 } 1704 1705 #ifdef MAC 1706 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1707 if (error != 0) 1708 goto out; 1709 #endif 1710 1711 mtx_lock(&shm_timestamp_lock); 1712 vfs_timestamp(&shmfd->shm_atime); 1713 mtx_unlock(&shm_timestamp_lock); 1714 vm_object_reference(shmfd->shm_object); 1715 1716 if (shm_largepage(shmfd)) { 1717 writecnt = false; 1718 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1719 maxprot, flags, foff, td); 1720 } else { 1721 if (writecnt) { 1722 vm_pager_update_writecount(shmfd->shm_object, 0, 1723 objsize); 1724 } 1725 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1726 shmfd->shm_object, foff, writecnt, td); 1727 } 1728 if (error != 0) { 1729 if (writecnt) 1730 vm_pager_release_writecount(shmfd->shm_object, 0, 1731 objsize); 1732 vm_object_deallocate(shmfd->shm_object); 1733 } 1734 out: 1735 shm_rangelock_unlock(shmfd, rl_cookie); 1736 return (error); 1737 } 1738 1739 static int 1740 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1741 struct thread *td) 1742 { 1743 struct shmfd *shmfd; 1744 int error; 1745 1746 error = 0; 1747 shmfd = fp->f_data; 1748 mtx_lock(&shm_timestamp_lock); 1749 /* 1750 * SUSv4 says that x bits of permission need not be affected. 1751 * Be consistent with our shm_open there. 1752 */ 1753 #ifdef MAC 1754 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1755 if (error != 0) 1756 goto out; 1757 #endif 1758 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1759 VADMIN, active_cred); 1760 if (error != 0) 1761 goto out; 1762 shmfd->shm_mode = mode & ACCESSPERMS; 1763 out: 1764 mtx_unlock(&shm_timestamp_lock); 1765 return (error); 1766 } 1767 1768 static int 1769 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1770 struct thread *td) 1771 { 1772 struct shmfd *shmfd; 1773 int error; 1774 1775 error = 0; 1776 shmfd = fp->f_data; 1777 mtx_lock(&shm_timestamp_lock); 1778 #ifdef MAC 1779 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1780 if (error != 0) 1781 goto out; 1782 #endif 1783 if (uid == (uid_t)-1) 1784 uid = shmfd->shm_uid; 1785 if (gid == (gid_t)-1) 1786 gid = shmfd->shm_gid; 1787 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1788 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1789 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1790 goto out; 1791 shmfd->shm_uid = uid; 1792 shmfd->shm_gid = gid; 1793 out: 1794 mtx_unlock(&shm_timestamp_lock); 1795 return (error); 1796 } 1797 1798 /* 1799 * Helper routines to allow the backing object of a shared memory file 1800 * descriptor to be mapped in the kernel. 1801 */ 1802 int 1803 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1804 { 1805 struct shmfd *shmfd; 1806 vm_offset_t kva, ofs; 1807 vm_object_t obj; 1808 int rv; 1809 1810 if (fp->f_type != DTYPE_SHM) 1811 return (EINVAL); 1812 shmfd = fp->f_data; 1813 obj = shmfd->shm_object; 1814 VM_OBJECT_WLOCK(obj); 1815 /* 1816 * XXXRW: This validation is probably insufficient, and subject to 1817 * sign errors. It should be fixed. 1818 */ 1819 if (offset >= shmfd->shm_size || 1820 offset + size > round_page(shmfd->shm_size)) { 1821 VM_OBJECT_WUNLOCK(obj); 1822 return (EINVAL); 1823 } 1824 1825 shmfd->shm_kmappings++; 1826 vm_object_reference_locked(obj); 1827 VM_OBJECT_WUNLOCK(obj); 1828 1829 /* Map the object into the kernel_map and wire it. */ 1830 kva = vm_map_min(kernel_map); 1831 ofs = offset & PAGE_MASK; 1832 offset = trunc_page(offset); 1833 size = round_page(size + ofs); 1834 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1835 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1836 VM_PROT_READ | VM_PROT_WRITE, 0); 1837 if (rv == KERN_SUCCESS) { 1838 rv = vm_map_wire(kernel_map, kva, kva + size, 1839 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1840 if (rv == KERN_SUCCESS) { 1841 *memp = (void *)(kva + ofs); 1842 return (0); 1843 } 1844 vm_map_remove(kernel_map, kva, kva + size); 1845 } else 1846 vm_object_deallocate(obj); 1847 1848 /* On failure, drop our mapping reference. */ 1849 VM_OBJECT_WLOCK(obj); 1850 shmfd->shm_kmappings--; 1851 VM_OBJECT_WUNLOCK(obj); 1852 1853 return (vm_mmap_to_errno(rv)); 1854 } 1855 1856 /* 1857 * We require the caller to unmap the entire entry. This allows us to 1858 * safely decrement shm_kmappings when a mapping is removed. 1859 */ 1860 int 1861 shm_unmap(struct file *fp, void *mem, size_t size) 1862 { 1863 struct shmfd *shmfd; 1864 vm_map_entry_t entry; 1865 vm_offset_t kva, ofs; 1866 vm_object_t obj; 1867 vm_pindex_t pindex; 1868 vm_prot_t prot; 1869 boolean_t wired; 1870 vm_map_t map; 1871 int rv; 1872 1873 if (fp->f_type != DTYPE_SHM) 1874 return (EINVAL); 1875 shmfd = fp->f_data; 1876 kva = (vm_offset_t)mem; 1877 ofs = kva & PAGE_MASK; 1878 kva = trunc_page(kva); 1879 size = round_page(size + ofs); 1880 map = kernel_map; 1881 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1882 &obj, &pindex, &prot, &wired); 1883 if (rv != KERN_SUCCESS) 1884 return (EINVAL); 1885 if (entry->start != kva || entry->end != kva + size) { 1886 vm_map_lookup_done(map, entry); 1887 return (EINVAL); 1888 } 1889 vm_map_lookup_done(map, entry); 1890 if (obj != shmfd->shm_object) 1891 return (EINVAL); 1892 vm_map_remove(map, kva, kva + size); 1893 VM_OBJECT_WLOCK(obj); 1894 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1895 shmfd->shm_kmappings--; 1896 VM_OBJECT_WUNLOCK(obj); 1897 return (0); 1898 } 1899 1900 static int 1901 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1902 { 1903 const char *path, *pr_path; 1904 size_t pr_pathlen; 1905 bool visible; 1906 1907 sx_assert(&shm_dict_lock, SA_LOCKED); 1908 kif->kf_type = KF_TYPE_SHM; 1909 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1910 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1911 if (shmfd->shm_path != NULL) { 1912 path = shmfd->shm_path; 1913 pr_path = curthread->td_ucred->cr_prison->pr_path; 1914 if (strcmp(pr_path, "/") != 0) { 1915 /* Return the jail-rooted pathname. */ 1916 pr_pathlen = strlen(pr_path); 1917 visible = strncmp(path, pr_path, pr_pathlen) == 0 && 1918 path[pr_pathlen] == '/'; 1919 if (list && !visible) 1920 return (EPERM); 1921 if (visible) 1922 path += pr_pathlen; 1923 } 1924 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1925 } 1926 return (0); 1927 } 1928 1929 static int 1930 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1931 struct filedesc *fdp __unused) 1932 { 1933 int res; 1934 1935 sx_slock(&shm_dict_lock); 1936 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1937 sx_sunlock(&shm_dict_lock); 1938 return (res); 1939 } 1940 1941 static int 1942 shm_add_seals(struct file *fp, int seals) 1943 { 1944 struct shmfd *shmfd; 1945 void *rl_cookie; 1946 vm_ooffset_t writemappings; 1947 int error, nseals; 1948 1949 error = 0; 1950 shmfd = fp->f_data; 1951 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1952 1953 /* Even already-set seals should result in EPERM. */ 1954 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1955 error = EPERM; 1956 goto out; 1957 } 1958 nseals = seals & ~shmfd->shm_seals; 1959 if ((nseals & F_SEAL_WRITE) != 0) { 1960 if (shm_largepage(shmfd)) { 1961 error = ENOTSUP; 1962 goto out; 1963 } 1964 1965 /* 1966 * The rangelock above prevents writable mappings from being 1967 * added after we've started applying seals. The RLOCK here 1968 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1969 * writemappings will be done without a rangelock. 1970 */ 1971 VM_OBJECT_RLOCK(shmfd->shm_object); 1972 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1973 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1974 /* kmappings are also writable */ 1975 if (writemappings > 0) { 1976 error = EBUSY; 1977 goto out; 1978 } 1979 } 1980 shmfd->shm_seals |= nseals; 1981 out: 1982 shm_rangelock_unlock(shmfd, rl_cookie); 1983 return (error); 1984 } 1985 1986 static int 1987 shm_get_seals(struct file *fp, int *seals) 1988 { 1989 struct shmfd *shmfd; 1990 1991 shmfd = fp->f_data; 1992 *seals = shmfd->shm_seals; 1993 return (0); 1994 } 1995 1996 static int 1997 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 1998 { 1999 vm_object_t object; 2000 vm_pindex_t pistart, pi, piend; 2001 vm_ooffset_t off, len; 2002 int startofs, endofs, end; 2003 int error; 2004 2005 off = *offset; 2006 len = *length; 2007 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 2008 if (off + len > shmfd->shm_size) 2009 len = shmfd->shm_size - off; 2010 object = shmfd->shm_object; 2011 startofs = off & PAGE_MASK; 2012 endofs = (off + len) & PAGE_MASK; 2013 pistart = OFF_TO_IDX(off); 2014 piend = OFF_TO_IDX(off + len); 2015 pi = OFF_TO_IDX(off + PAGE_MASK); 2016 error = 0; 2017 2018 /* Handle the case when offset is on or beyond shm size. */ 2019 if ((off_t)len <= 0) { 2020 *length = 0; 2021 return (0); 2022 } 2023 2024 VM_OBJECT_WLOCK(object); 2025 2026 if (startofs != 0) { 2027 end = pistart != piend ? PAGE_SIZE : endofs; 2028 error = shm_partial_page_invalidate(object, pistart, startofs, 2029 end); 2030 if (error) 2031 goto out; 2032 off += end - startofs; 2033 len -= end - startofs; 2034 } 2035 2036 if (pi < piend) { 2037 vm_object_page_remove(object, pi, piend, 0); 2038 off += IDX_TO_OFF(piend - pi); 2039 len -= IDX_TO_OFF(piend - pi); 2040 } 2041 2042 if (endofs != 0 && pistart != piend) { 2043 error = shm_partial_page_invalidate(object, piend, 0, endofs); 2044 if (error) 2045 goto out; 2046 off += endofs; 2047 len -= endofs; 2048 } 2049 2050 out: 2051 VM_OBJECT_WUNLOCK(shmfd->shm_object); 2052 *offset = off; 2053 *length = len; 2054 return (error); 2055 } 2056 2057 static int 2058 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 2059 struct ucred *active_cred, struct thread *td) 2060 { 2061 void *rl_cookie; 2062 struct shmfd *shmfd; 2063 off_t off, len; 2064 int error; 2065 2066 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd")); 2067 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0, 2068 ("shm_fspacectl: non-zero flags")); 2069 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset, 2070 ("shm_fspacectl: offset/length overflow or underflow")); 2071 error = EINVAL; 2072 shmfd = fp->f_data; 2073 off = *offset; 2074 len = *length; 2075 2076 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len); 2077 switch (cmd) { 2078 case SPACECTL_DEALLOC: 2079 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2080 error = EPERM; 2081 break; 2082 } 2083 error = shm_deallocate(shmfd, &off, &len, flags); 2084 *offset = off; 2085 *length = len; 2086 break; 2087 default: 2088 __assert_unreachable(); 2089 } 2090 shm_rangelock_unlock(shmfd, rl_cookie); 2091 return (error); 2092 } 2093 2094 2095 static int 2096 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2097 { 2098 void *rl_cookie; 2099 struct shmfd *shmfd; 2100 size_t size; 2101 int error; 2102 2103 /* This assumes that the caller already checked for overflow. */ 2104 error = 0; 2105 shmfd = fp->f_data; 2106 size = offset + len; 2107 2108 /* 2109 * Just grab the rangelock for the range that we may be attempting to 2110 * grow, rather than blocking read/write for regions we won't be 2111 * touching while this (potential) resize is in progress. Other 2112 * attempts to resize the shmfd will have to take a write lock from 0 to 2113 * OFF_MAX, so this being potentially beyond the current usable range of 2114 * the shmfd is not necessarily a concern. If other mechanisms are 2115 * added to grow a shmfd, this may need to be re-evaluated. 2116 */ 2117 rl_cookie = shm_rangelock_wlock(shmfd, offset, size); 2118 if (size > shmfd->shm_size) 2119 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2120 shm_rangelock_unlock(shmfd, rl_cookie); 2121 /* Translate to posix_fallocate(2) return value as needed. */ 2122 if (error == ENOMEM) 2123 error = ENOSPC; 2124 return (error); 2125 } 2126 2127 static int 2128 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2129 { 2130 struct shm_mapping *shmm; 2131 struct sbuf sb; 2132 struct kinfo_file kif; 2133 u_long i; 2134 int error, error2; 2135 2136 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2137 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2138 error = 0; 2139 sx_slock(&shm_dict_lock); 2140 for (i = 0; i < shm_hash + 1; i++) { 2141 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2142 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2143 &kif, true); 2144 if (error == EPERM) { 2145 error = 0; 2146 continue; 2147 } 2148 if (error != 0) 2149 break; 2150 pack_kinfo(&kif); 2151 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2152 0 : ENOMEM; 2153 if (error != 0) 2154 break; 2155 } 2156 } 2157 sx_sunlock(&shm_dict_lock); 2158 error2 = sbuf_finish(&sb); 2159 sbuf_delete(&sb); 2160 return (error != 0 ? error : error2); 2161 } 2162 2163 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2164 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2165 NULL, 0, sysctl_posix_shm_list, "", 2166 "POSIX SHM list"); 2167 2168 int 2169 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2170 struct filecaps *caps) 2171 { 2172 2173 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2174 } 2175 2176 /* 2177 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2178 * caller, and libc will enforce it for the traditional shm_open() call. This 2179 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2180 * interface also includes a 'name' argument that is currently unused, but could 2181 * potentially be exported later via some interface for debugging purposes. 2182 * From the kernel's perspective, it is optional. Individual consumers like 2183 * memfd_create() may require it in order to be compatible with other systems 2184 * implementing the same function. 2185 */ 2186 int 2187 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2188 { 2189 2190 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2191 uap->shmflags, NULL, uap->name)); 2192 } 2193 2194 int 2195 shm_get_path(struct vm_object *obj, char *path, size_t sz) 2196 { 2197 struct shmfd *shmfd; 2198 int error; 2199 2200 error = 0; 2201 shmfd = NULL; 2202 sx_slock(&shm_dict_lock); 2203 VM_OBJECT_RLOCK(obj); 2204 if ((obj->flags & OBJ_POSIXSHM) == 0) { 2205 error = EINVAL; 2206 } else { 2207 if (obj->type == shmfd_pager_type) 2208 shmfd = obj->un_pager.swp.swp_priv; 2209 else if (obj->type == OBJT_PHYS) 2210 shmfd = obj->un_pager.phys.phys_priv; 2211 if (shmfd == NULL) { 2212 error = ENXIO; 2213 } else { 2214 strlcpy(path, shmfd->shm_path == NULL ? "anon" : 2215 shmfd->shm_path, sz); 2216 } 2217 } 2218 if (error != 0) 2219 path[0] = '\0'; 2220 VM_OBJECT_RUNLOCK(obj); 2221 sx_sunlock(&shm_dict_lock); 2222 return (error); 2223 } 2224