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 #ifdef CAPABILITY_MODE 1177 /* 1178 * shm_open(2) is only allowed for anonymous objects. 1179 */ 1180 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1181 return (ECAPMODE); 1182 #endif 1183 1184 AUDIT_ARG_FFLAGS(flags); 1185 AUDIT_ARG_MODE(mode); 1186 1187 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1188 return (EINVAL); 1189 1190 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1191 return (EINVAL); 1192 1193 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1194 if (largepage && !PMAP_HAS_LARGEPAGES) 1195 return (ENOTTY); 1196 1197 /* 1198 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1199 * If the decision is made later to allow additional seals, care must be 1200 * taken below to ensure that the seals are properly set if the shmfd 1201 * already existed -- this currently assumes that only F_SEAL_SEAL can 1202 * be set and doesn't take further precautions to ensure the validity of 1203 * the seals being added with respect to current mappings. 1204 */ 1205 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1206 return (EINVAL); 1207 1208 pdp = td->td_proc->p_pd; 1209 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1210 1211 /* 1212 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1213 * by POSIX. We allow it to be unset here so that an in-kernel 1214 * interface may be written as a thin layer around shm, optionally not 1215 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1216 * in sys_shm_open() to keep this implementation compliant. 1217 */ 1218 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1219 if (error) 1220 return (error); 1221 1222 /* A SHM_ANON path pointer creates an anonymous object. */ 1223 if (userpath == SHM_ANON) { 1224 /* A read-only anonymous object is pointless. */ 1225 if ((flags & O_ACCMODE) == O_RDONLY) { 1226 fdclose(td, fp, fd); 1227 fdrop(fp, td); 1228 return (EINVAL); 1229 } 1230 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1231 shmfd->shm_seals = initial_seals; 1232 shmfd->shm_flags = shmflags; 1233 } else { 1234 error = shm_copyin_path(td, userpath, &path); 1235 if (error != 0) { 1236 fdclose(td, fp, fd); 1237 fdrop(fp, td); 1238 return (error); 1239 } 1240 1241 AUDIT_ARG_UPATH1_CANON(path); 1242 fnv = fnv_32_str(path, FNV1_32_INIT); 1243 sx_xlock(&shm_dict_lock); 1244 shmfd = shm_lookup(path, fnv); 1245 if (shmfd == NULL) { 1246 /* Object does not yet exist, create it if requested. */ 1247 if (flags & O_CREAT) { 1248 #ifdef MAC 1249 error = mac_posixshm_check_create(td->td_ucred, 1250 path); 1251 if (error == 0) { 1252 #endif 1253 shmfd = shm_alloc(td->td_ucred, cmode, 1254 largepage); 1255 shmfd->shm_seals = initial_seals; 1256 shmfd->shm_flags = shmflags; 1257 shm_insert(path, fnv, shmfd); 1258 #ifdef MAC 1259 } 1260 #endif 1261 } else { 1262 free(path, M_SHMFD); 1263 error = ENOENT; 1264 } 1265 } else { 1266 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1267 1268 /* 1269 * kern_shm_open() likely shouldn't ever error out on 1270 * trying to set a seal that already exists, unlike 1271 * F_ADD_SEALS. This would break terribly as 1272 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1273 * historical behavior where the underlying file could 1274 * not be sealed. 1275 */ 1276 initial_seals &= ~shmfd->shm_seals; 1277 1278 /* 1279 * Object already exists, obtain a new 1280 * reference if requested and permitted. 1281 */ 1282 free(path, M_SHMFD); 1283 1284 /* 1285 * initial_seals can't set additional seals if we've 1286 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1287 * then we've already removed that one from 1288 * initial_seals. This is currently redundant as we 1289 * only allow setting F_SEAL_SEAL at creation time, but 1290 * it's cheap to check and decreases the effort required 1291 * to allow additional seals. 1292 */ 1293 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1294 initial_seals != 0) 1295 error = EPERM; 1296 else if ((flags & (O_CREAT | O_EXCL)) == 1297 (O_CREAT | O_EXCL)) 1298 error = EEXIST; 1299 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1300 error = EINVAL; 1301 else { 1302 #ifdef MAC 1303 error = mac_posixshm_check_open(td->td_ucred, 1304 shmfd, FFLAGS(flags & O_ACCMODE)); 1305 if (error == 0) 1306 #endif 1307 error = shm_access(shmfd, td->td_ucred, 1308 FFLAGS(flags & O_ACCMODE)); 1309 } 1310 1311 /* 1312 * Truncate the file back to zero length if 1313 * O_TRUNC was specified and the object was 1314 * opened with read/write. 1315 */ 1316 if (error == 0 && 1317 (flags & (O_ACCMODE | O_TRUNC)) == 1318 (O_RDWR | O_TRUNC)) { 1319 VM_OBJECT_WLOCK(shmfd->shm_object); 1320 #ifdef MAC 1321 error = mac_posixshm_check_truncate( 1322 td->td_ucred, fp->f_cred, shmfd); 1323 if (error == 0) 1324 #endif 1325 error = shm_dotruncate_locked(shmfd, 0, 1326 rl_cookie); 1327 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1328 } 1329 if (error == 0) { 1330 /* 1331 * Currently we only allow F_SEAL_SEAL to be 1332 * set initially. As noted above, this would 1333 * need to be reworked should that change. 1334 */ 1335 shmfd->shm_seals |= initial_seals; 1336 shm_hold(shmfd); 1337 } 1338 shm_rangelock_unlock(shmfd, rl_cookie); 1339 } 1340 sx_xunlock(&shm_dict_lock); 1341 1342 if (error) { 1343 fdclose(td, fp, fd); 1344 fdrop(fp, td); 1345 return (error); 1346 } 1347 } 1348 1349 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1350 1351 td->td_retval[0] = fd; 1352 fdrop(fp, td); 1353 1354 return (0); 1355 } 1356 1357 /* System calls. */ 1358 #ifdef COMPAT_FREEBSD12 1359 int 1360 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1361 { 1362 1363 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1364 uap->mode, NULL)); 1365 } 1366 #endif 1367 1368 int 1369 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1370 { 1371 char *path; 1372 Fnv32_t fnv; 1373 int error; 1374 1375 error = shm_copyin_path(td, uap->path, &path); 1376 if (error != 0) 1377 return (error); 1378 1379 AUDIT_ARG_UPATH1_CANON(path); 1380 fnv = fnv_32_str(path, FNV1_32_INIT); 1381 sx_xlock(&shm_dict_lock); 1382 error = shm_remove(path, fnv, td->td_ucred); 1383 sx_xunlock(&shm_dict_lock); 1384 free(path, M_SHMFD); 1385 1386 return (error); 1387 } 1388 1389 int 1390 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1391 { 1392 char *path_from = NULL, *path_to = NULL; 1393 Fnv32_t fnv_from, fnv_to; 1394 struct shmfd *fd_from; 1395 struct shmfd *fd_to; 1396 int error; 1397 int flags; 1398 1399 flags = uap->flags; 1400 AUDIT_ARG_FFLAGS(flags); 1401 1402 /* 1403 * Make sure the user passed only valid flags. 1404 * If you add a new flag, please add a new term here. 1405 */ 1406 if ((flags & ~( 1407 SHM_RENAME_NOREPLACE | 1408 SHM_RENAME_EXCHANGE 1409 )) != 0) { 1410 error = EINVAL; 1411 goto out; 1412 } 1413 1414 /* 1415 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1416 * force the user to choose one or the other. 1417 */ 1418 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1419 (flags & SHM_RENAME_EXCHANGE) != 0) { 1420 error = EINVAL; 1421 goto out; 1422 } 1423 1424 /* Renaming to or from anonymous makes no sense */ 1425 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1426 error = EINVAL; 1427 goto out; 1428 } 1429 1430 error = shm_copyin_path(td, uap->path_from, &path_from); 1431 if (error != 0) 1432 goto out; 1433 1434 error = shm_copyin_path(td, uap->path_to, &path_to); 1435 if (error != 0) 1436 goto out; 1437 1438 AUDIT_ARG_UPATH1_CANON(path_from); 1439 AUDIT_ARG_UPATH2_CANON(path_to); 1440 1441 /* Rename with from/to equal is a no-op */ 1442 if (strcmp(path_from, path_to) == 0) 1443 goto out; 1444 1445 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1446 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1447 1448 sx_xlock(&shm_dict_lock); 1449 1450 fd_from = shm_lookup(path_from, fnv_from); 1451 if (fd_from == NULL) { 1452 error = ENOENT; 1453 goto out_locked; 1454 } 1455 1456 fd_to = shm_lookup(path_to, fnv_to); 1457 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1458 error = EEXIST; 1459 goto out_locked; 1460 } 1461 1462 /* 1463 * Unconditionally prevents shm_remove from invalidating the 'from' 1464 * shm's state. 1465 */ 1466 shm_hold(fd_from); 1467 error = shm_remove(path_from, fnv_from, td->td_ucred); 1468 1469 /* 1470 * One of my assumptions failed if ENOENT (e.g. locking didn't 1471 * protect us) 1472 */ 1473 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1474 path_from)); 1475 if (error != 0) { 1476 shm_drop(fd_from); 1477 goto out_locked; 1478 } 1479 1480 /* 1481 * If we are exchanging, we need to ensure the shm_remove below 1482 * doesn't invalidate the dest shm's state. 1483 */ 1484 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1485 shm_hold(fd_to); 1486 1487 /* 1488 * NOTE: if path_to is not already in the hash, c'est la vie; 1489 * it simply means we have nothing already at path_to to unlink. 1490 * That is the ENOENT case. 1491 * 1492 * If we somehow don't have access to unlink this guy, but 1493 * did for the shm at path_from, then relink the shm to path_from 1494 * and abort with EACCES. 1495 * 1496 * All other errors: that is weird; let's relink and abort the 1497 * operation. 1498 */ 1499 error = shm_remove(path_to, fnv_to, td->td_ucred); 1500 if (error != 0 && error != ENOENT) { 1501 shm_insert(path_from, fnv_from, fd_from); 1502 shm_drop(fd_from); 1503 /* Don't free path_from now, since the hash references it */ 1504 path_from = NULL; 1505 goto out_locked; 1506 } 1507 1508 error = 0; 1509 1510 shm_insert(path_to, fnv_to, fd_from); 1511 1512 /* Don't free path_to now, since the hash references it */ 1513 path_to = NULL; 1514 1515 /* We kept a ref when we removed, and incremented again in insert */ 1516 shm_drop(fd_from); 1517 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1518 fd_from->shm_refs)); 1519 1520 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1521 shm_insert(path_from, fnv_from, fd_to); 1522 path_from = NULL; 1523 shm_drop(fd_to); 1524 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1525 fd_to->shm_refs)); 1526 } 1527 1528 out_locked: 1529 sx_xunlock(&shm_dict_lock); 1530 1531 out: 1532 free(path_from, M_SHMFD); 1533 free(path_to, M_SHMFD); 1534 return (error); 1535 } 1536 1537 static int 1538 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1539 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1540 vm_ooffset_t foff, struct thread *td) 1541 { 1542 struct vmspace *vms; 1543 vm_map_entry_t next_entry, prev_entry; 1544 vm_offset_t align, mask, maxaddr; 1545 int docow, error, rv, try; 1546 bool curmap; 1547 1548 if (shmfd->shm_lp_psind == 0) 1549 return (EINVAL); 1550 1551 /* MAP_PRIVATE is disabled */ 1552 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1553 MAP_NOCORE | MAP_32BIT | MAP_ALIGNMENT_MASK)) != 0) 1554 return (EINVAL); 1555 1556 vms = td->td_proc->p_vmspace; 1557 curmap = map == &vms->vm_map; 1558 if (curmap) { 1559 error = kern_mmap_racct_check(td, map, size); 1560 if (error != 0) 1561 return (error); 1562 } 1563 1564 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1565 docow |= MAP_INHERIT_SHARE; 1566 if ((flags & MAP_NOCORE) != 0) 1567 docow |= MAP_DISABLE_COREDUMP; 1568 1569 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1570 if ((foff & mask) != 0) 1571 return (EINVAL); 1572 maxaddr = vm_map_max(map); 1573 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1574 maxaddr = MAP_32BIT_MAX_ADDR; 1575 if (size == 0 || (size & mask) != 0 || 1576 (*addr != 0 && ((*addr & mask) != 0 || 1577 *addr + size < *addr || *addr + size > maxaddr))) 1578 return (EINVAL); 1579 1580 align = flags & MAP_ALIGNMENT_MASK; 1581 if (align == 0) { 1582 align = pagesizes[shmfd->shm_lp_psind]; 1583 } else if (align == MAP_ALIGNED_SUPER) { 1584 if (shmfd->shm_lp_psind != 1) 1585 return (EINVAL); 1586 align = pagesizes[1]; 1587 } else { 1588 align >>= MAP_ALIGNMENT_SHIFT; 1589 align = 1ULL << align; 1590 /* Also handles overflow. */ 1591 if (align < pagesizes[shmfd->shm_lp_psind]) 1592 return (EINVAL); 1593 } 1594 1595 vm_map_lock(map); 1596 if ((flags & MAP_FIXED) == 0) { 1597 try = 1; 1598 if (curmap && (*addr == 0 || 1599 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1600 *addr < round_page((vm_offset_t)vms->vm_daddr + 1601 lim_max(td, RLIMIT_DATA))))) { 1602 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1603 lim_max(td, RLIMIT_DATA), 1604 pagesizes[shmfd->shm_lp_psind]); 1605 } 1606 again: 1607 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1608 if (rv != KERN_SUCCESS) { 1609 if (try == 1) { 1610 try = 2; 1611 *addr = vm_map_min(map); 1612 if ((*addr & mask) != 0) 1613 *addr = (*addr + mask) & mask; 1614 goto again; 1615 } 1616 goto fail1; 1617 } 1618 } else if ((flags & MAP_EXCL) == 0) { 1619 rv = vm_map_delete(map, *addr, *addr + size); 1620 if (rv != KERN_SUCCESS) 1621 goto fail1; 1622 } else { 1623 error = ENOSPC; 1624 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1625 goto fail; 1626 next_entry = vm_map_entry_succ(prev_entry); 1627 if (next_entry->start < *addr + size) 1628 goto fail; 1629 } 1630 1631 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1632 prot, max_prot, docow); 1633 fail1: 1634 error = vm_mmap_to_errno(rv); 1635 fail: 1636 vm_map_unlock(map); 1637 return (error); 1638 } 1639 1640 static int 1641 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1642 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1643 vm_ooffset_t foff, struct thread *td) 1644 { 1645 struct shmfd *shmfd; 1646 vm_prot_t maxprot; 1647 int error; 1648 bool writecnt; 1649 void *rl_cookie; 1650 1651 shmfd = fp->f_data; 1652 maxprot = VM_PROT_NONE; 1653 1654 rl_cookie = shm_rangelock_rlock(shmfd, 0, objsize); 1655 /* FREAD should always be set. */ 1656 if ((fp->f_flag & FREAD) != 0) 1657 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1658 1659 /* 1660 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1661 * mapping with a write seal applied. Private mappings are always 1662 * writeable. 1663 */ 1664 if ((flags & MAP_SHARED) == 0) { 1665 cap_maxprot |= VM_PROT_WRITE; 1666 maxprot |= VM_PROT_WRITE; 1667 writecnt = false; 1668 } else { 1669 if ((fp->f_flag & FWRITE) != 0 && 1670 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1671 maxprot |= VM_PROT_WRITE; 1672 1673 /* 1674 * Any mappings from a writable descriptor may be upgraded to 1675 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1676 * applied between the open and subsequent mmap(2). We want to 1677 * reject application of a write seal as long as any such 1678 * mapping exists so that the seal cannot be trivially bypassed. 1679 */ 1680 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1681 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1682 error = EACCES; 1683 goto out; 1684 } 1685 } 1686 maxprot &= cap_maxprot; 1687 1688 /* See comment in vn_mmap(). */ 1689 if ( 1690 #ifdef _LP64 1691 objsize > OFF_MAX || 1692 #endif 1693 foff > OFF_MAX - objsize) { 1694 error = EINVAL; 1695 goto out; 1696 } 1697 1698 #ifdef MAC 1699 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1700 if (error != 0) 1701 goto out; 1702 #endif 1703 1704 mtx_lock(&shm_timestamp_lock); 1705 vfs_timestamp(&shmfd->shm_atime); 1706 mtx_unlock(&shm_timestamp_lock); 1707 vm_object_reference(shmfd->shm_object); 1708 1709 if (shm_largepage(shmfd)) { 1710 writecnt = false; 1711 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1712 maxprot, flags, foff, td); 1713 } else { 1714 if (writecnt) { 1715 vm_pager_update_writecount(shmfd->shm_object, 0, 1716 objsize); 1717 } 1718 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1719 shmfd->shm_object, foff, writecnt, td); 1720 } 1721 if (error != 0) { 1722 if (writecnt) 1723 vm_pager_release_writecount(shmfd->shm_object, 0, 1724 objsize); 1725 vm_object_deallocate(shmfd->shm_object); 1726 } 1727 out: 1728 shm_rangelock_unlock(shmfd, rl_cookie); 1729 return (error); 1730 } 1731 1732 static int 1733 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1734 struct thread *td) 1735 { 1736 struct shmfd *shmfd; 1737 int error; 1738 1739 error = 0; 1740 shmfd = fp->f_data; 1741 mtx_lock(&shm_timestamp_lock); 1742 /* 1743 * SUSv4 says that x bits of permission need not be affected. 1744 * Be consistent with our shm_open there. 1745 */ 1746 #ifdef MAC 1747 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1748 if (error != 0) 1749 goto out; 1750 #endif 1751 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1752 VADMIN, active_cred); 1753 if (error != 0) 1754 goto out; 1755 shmfd->shm_mode = mode & ACCESSPERMS; 1756 out: 1757 mtx_unlock(&shm_timestamp_lock); 1758 return (error); 1759 } 1760 1761 static int 1762 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1763 struct thread *td) 1764 { 1765 struct shmfd *shmfd; 1766 int error; 1767 1768 error = 0; 1769 shmfd = fp->f_data; 1770 mtx_lock(&shm_timestamp_lock); 1771 #ifdef MAC 1772 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1773 if (error != 0) 1774 goto out; 1775 #endif 1776 if (uid == (uid_t)-1) 1777 uid = shmfd->shm_uid; 1778 if (gid == (gid_t)-1) 1779 gid = shmfd->shm_gid; 1780 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1781 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1782 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1783 goto out; 1784 shmfd->shm_uid = uid; 1785 shmfd->shm_gid = gid; 1786 out: 1787 mtx_unlock(&shm_timestamp_lock); 1788 return (error); 1789 } 1790 1791 /* 1792 * Helper routines to allow the backing object of a shared memory file 1793 * descriptor to be mapped in the kernel. 1794 */ 1795 int 1796 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1797 { 1798 struct shmfd *shmfd; 1799 vm_offset_t kva, ofs; 1800 vm_object_t obj; 1801 int rv; 1802 1803 if (fp->f_type != DTYPE_SHM) 1804 return (EINVAL); 1805 shmfd = fp->f_data; 1806 obj = shmfd->shm_object; 1807 VM_OBJECT_WLOCK(obj); 1808 /* 1809 * XXXRW: This validation is probably insufficient, and subject to 1810 * sign errors. It should be fixed. 1811 */ 1812 if (offset >= shmfd->shm_size || 1813 offset + size > round_page(shmfd->shm_size)) { 1814 VM_OBJECT_WUNLOCK(obj); 1815 return (EINVAL); 1816 } 1817 1818 shmfd->shm_kmappings++; 1819 vm_object_reference_locked(obj); 1820 VM_OBJECT_WUNLOCK(obj); 1821 1822 /* Map the object into the kernel_map and wire it. */ 1823 kva = vm_map_min(kernel_map); 1824 ofs = offset & PAGE_MASK; 1825 offset = trunc_page(offset); 1826 size = round_page(size + ofs); 1827 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1828 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1829 VM_PROT_READ | VM_PROT_WRITE, 0); 1830 if (rv == KERN_SUCCESS) { 1831 rv = vm_map_wire(kernel_map, kva, kva + size, 1832 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1833 if (rv == KERN_SUCCESS) { 1834 *memp = (void *)(kva + ofs); 1835 return (0); 1836 } 1837 vm_map_remove(kernel_map, kva, kva + size); 1838 } else 1839 vm_object_deallocate(obj); 1840 1841 /* On failure, drop our mapping reference. */ 1842 VM_OBJECT_WLOCK(obj); 1843 shmfd->shm_kmappings--; 1844 VM_OBJECT_WUNLOCK(obj); 1845 1846 return (vm_mmap_to_errno(rv)); 1847 } 1848 1849 /* 1850 * We require the caller to unmap the entire entry. This allows us to 1851 * safely decrement shm_kmappings when a mapping is removed. 1852 */ 1853 int 1854 shm_unmap(struct file *fp, void *mem, size_t size) 1855 { 1856 struct shmfd *shmfd; 1857 vm_map_entry_t entry; 1858 vm_offset_t kva, ofs; 1859 vm_object_t obj; 1860 vm_pindex_t pindex; 1861 vm_prot_t prot; 1862 boolean_t wired; 1863 vm_map_t map; 1864 int rv; 1865 1866 if (fp->f_type != DTYPE_SHM) 1867 return (EINVAL); 1868 shmfd = fp->f_data; 1869 kva = (vm_offset_t)mem; 1870 ofs = kva & PAGE_MASK; 1871 kva = trunc_page(kva); 1872 size = round_page(size + ofs); 1873 map = kernel_map; 1874 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1875 &obj, &pindex, &prot, &wired); 1876 if (rv != KERN_SUCCESS) 1877 return (EINVAL); 1878 if (entry->start != kva || entry->end != kva + size) { 1879 vm_map_lookup_done(map, entry); 1880 return (EINVAL); 1881 } 1882 vm_map_lookup_done(map, entry); 1883 if (obj != shmfd->shm_object) 1884 return (EINVAL); 1885 vm_map_remove(map, kva, kva + size); 1886 VM_OBJECT_WLOCK(obj); 1887 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1888 shmfd->shm_kmappings--; 1889 VM_OBJECT_WUNLOCK(obj); 1890 return (0); 1891 } 1892 1893 static int 1894 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1895 { 1896 const char *path, *pr_path; 1897 size_t pr_pathlen; 1898 bool visible; 1899 1900 sx_assert(&shm_dict_lock, SA_LOCKED); 1901 kif->kf_type = KF_TYPE_SHM; 1902 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1903 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1904 if (shmfd->shm_path != NULL) { 1905 if (shmfd->shm_path != NULL) { 1906 path = shmfd->shm_path; 1907 pr_path = curthread->td_ucred->cr_prison->pr_path; 1908 if (strcmp(pr_path, "/") != 0) { 1909 /* Return the jail-rooted pathname. */ 1910 pr_pathlen = strlen(pr_path); 1911 visible = strncmp(path, pr_path, pr_pathlen) 1912 == 0 && path[pr_pathlen] == '/'; 1913 if (list && !visible) 1914 return (EPERM); 1915 if (visible) 1916 path += pr_pathlen; 1917 } 1918 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1919 } 1920 } 1921 return (0); 1922 } 1923 1924 static int 1925 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1926 struct filedesc *fdp __unused) 1927 { 1928 int res; 1929 1930 sx_slock(&shm_dict_lock); 1931 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1932 sx_sunlock(&shm_dict_lock); 1933 return (res); 1934 } 1935 1936 static int 1937 shm_add_seals(struct file *fp, int seals) 1938 { 1939 struct shmfd *shmfd; 1940 void *rl_cookie; 1941 vm_ooffset_t writemappings; 1942 int error, nseals; 1943 1944 error = 0; 1945 shmfd = fp->f_data; 1946 rl_cookie = shm_rangelock_wlock(shmfd, 0, OFF_MAX); 1947 1948 /* Even already-set seals should result in EPERM. */ 1949 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1950 error = EPERM; 1951 goto out; 1952 } 1953 nseals = seals & ~shmfd->shm_seals; 1954 if ((nseals & F_SEAL_WRITE) != 0) { 1955 if (shm_largepage(shmfd)) { 1956 error = ENOTSUP; 1957 goto out; 1958 } 1959 1960 /* 1961 * The rangelock above prevents writable mappings from being 1962 * added after we've started applying seals. The RLOCK here 1963 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1964 * writemappings will be done without a rangelock. 1965 */ 1966 VM_OBJECT_RLOCK(shmfd->shm_object); 1967 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1968 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1969 /* kmappings are also writable */ 1970 if (writemappings > 0) { 1971 error = EBUSY; 1972 goto out; 1973 } 1974 } 1975 shmfd->shm_seals |= nseals; 1976 out: 1977 shm_rangelock_unlock(shmfd, rl_cookie); 1978 return (error); 1979 } 1980 1981 static int 1982 shm_get_seals(struct file *fp, int *seals) 1983 { 1984 struct shmfd *shmfd; 1985 1986 shmfd = fp->f_data; 1987 *seals = shmfd->shm_seals; 1988 return (0); 1989 } 1990 1991 static int 1992 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 1993 { 1994 vm_object_t object; 1995 vm_pindex_t pistart, pi, piend; 1996 vm_ooffset_t off, len; 1997 int startofs, endofs, end; 1998 int error; 1999 2000 off = *offset; 2001 len = *length; 2002 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 2003 if (off + len > shmfd->shm_size) 2004 len = shmfd->shm_size - off; 2005 object = shmfd->shm_object; 2006 startofs = off & PAGE_MASK; 2007 endofs = (off + len) & PAGE_MASK; 2008 pistart = OFF_TO_IDX(off); 2009 piend = OFF_TO_IDX(off + len); 2010 pi = OFF_TO_IDX(off + PAGE_MASK); 2011 error = 0; 2012 2013 /* Handle the case when offset is on or beyond shm size. */ 2014 if ((off_t)len <= 0) { 2015 *length = 0; 2016 return (0); 2017 } 2018 2019 VM_OBJECT_WLOCK(object); 2020 2021 if (startofs != 0) { 2022 end = pistart != piend ? PAGE_SIZE : endofs; 2023 error = shm_partial_page_invalidate(object, pistart, startofs, 2024 end); 2025 if (error) 2026 goto out; 2027 off += end - startofs; 2028 len -= end - startofs; 2029 } 2030 2031 if (pi < piend) { 2032 vm_object_page_remove(object, pi, piend, 0); 2033 off += IDX_TO_OFF(piend - pi); 2034 len -= IDX_TO_OFF(piend - pi); 2035 } 2036 2037 if (endofs != 0 && pistart != piend) { 2038 error = shm_partial_page_invalidate(object, piend, 0, endofs); 2039 if (error) 2040 goto out; 2041 off += endofs; 2042 len -= endofs; 2043 } 2044 2045 out: 2046 VM_OBJECT_WUNLOCK(shmfd->shm_object); 2047 *offset = off; 2048 *length = len; 2049 return (error); 2050 } 2051 2052 static int 2053 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 2054 struct ucred *active_cred, struct thread *td) 2055 { 2056 void *rl_cookie; 2057 struct shmfd *shmfd; 2058 off_t off, len; 2059 int error; 2060 2061 KASSERT(cmd == SPACECTL_DEALLOC, ("shm_fspacectl: Invalid cmd")); 2062 KASSERT((flags & ~SPACECTL_F_SUPPORTED) == 0, 2063 ("shm_fspacectl: non-zero flags")); 2064 KASSERT(*offset >= 0 && *length > 0 && *length <= OFF_MAX - *offset, 2065 ("shm_fspacectl: offset/length overflow or underflow")); 2066 error = EINVAL; 2067 shmfd = fp->f_data; 2068 off = *offset; 2069 len = *length; 2070 2071 rl_cookie = shm_rangelock_wlock(shmfd, off, off + len); 2072 switch (cmd) { 2073 case SPACECTL_DEALLOC: 2074 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2075 error = EPERM; 2076 break; 2077 } 2078 error = shm_deallocate(shmfd, &off, &len, flags); 2079 *offset = off; 2080 *length = len; 2081 break; 2082 default: 2083 __assert_unreachable(); 2084 } 2085 shm_rangelock_unlock(shmfd, rl_cookie); 2086 return (error); 2087 } 2088 2089 2090 static int 2091 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2092 { 2093 void *rl_cookie; 2094 struct shmfd *shmfd; 2095 size_t size; 2096 int error; 2097 2098 /* This assumes that the caller already checked for overflow. */ 2099 error = 0; 2100 shmfd = fp->f_data; 2101 size = offset + len; 2102 2103 /* 2104 * Just grab the rangelock for the range that we may be attempting to 2105 * grow, rather than blocking read/write for regions we won't be 2106 * touching while this (potential) resize is in progress. Other 2107 * attempts to resize the shmfd will have to take a write lock from 0 to 2108 * OFF_MAX, so this being potentially beyond the current usable range of 2109 * the shmfd is not necessarily a concern. If other mechanisms are 2110 * added to grow a shmfd, this may need to be re-evaluated. 2111 */ 2112 rl_cookie = shm_rangelock_wlock(shmfd, offset, size); 2113 if (size > shmfd->shm_size) 2114 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2115 shm_rangelock_unlock(shmfd, rl_cookie); 2116 /* Translate to posix_fallocate(2) return value as needed. */ 2117 if (error == ENOMEM) 2118 error = ENOSPC; 2119 return (error); 2120 } 2121 2122 static int 2123 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2124 { 2125 struct shm_mapping *shmm; 2126 struct sbuf sb; 2127 struct kinfo_file kif; 2128 u_long i; 2129 int error, error2; 2130 2131 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2132 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2133 error = 0; 2134 sx_slock(&shm_dict_lock); 2135 for (i = 0; i < shm_hash + 1; i++) { 2136 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2137 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2138 &kif, true); 2139 if (error == EPERM) { 2140 error = 0; 2141 continue; 2142 } 2143 if (error != 0) 2144 break; 2145 pack_kinfo(&kif); 2146 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2147 0 : ENOMEM; 2148 if (error != 0) 2149 break; 2150 } 2151 } 2152 sx_sunlock(&shm_dict_lock); 2153 error2 = sbuf_finish(&sb); 2154 sbuf_delete(&sb); 2155 return (error != 0 ? error : error2); 2156 } 2157 2158 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2159 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2160 NULL, 0, sysctl_posix_shm_list, "", 2161 "POSIX SHM list"); 2162 2163 int 2164 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2165 struct filecaps *caps) 2166 { 2167 2168 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2169 } 2170 2171 /* 2172 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2173 * caller, and libc will enforce it for the traditional shm_open() call. This 2174 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2175 * interface also includes a 'name' argument that is currently unused, but could 2176 * potentially be exported later via some interface for debugging purposes. 2177 * From the kernel's perspective, it is optional. Individual consumers like 2178 * memfd_create() may require it in order to be compatible with other systems 2179 * implementing the same function. 2180 */ 2181 int 2182 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2183 { 2184 2185 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2186 uap->shmflags, NULL, uap->name)); 2187 } 2188