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