1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 __FBSDID("$FreeBSD$"); 52 53 #include "opt_capsicum.h" 54 #include "opt_ktrace.h" 55 56 #include <sys/param.h> 57 #include <sys/capsicum.h> 58 #include <sys/conf.h> 59 #include <sys/fcntl.h> 60 #include <sys/file.h> 61 #include <sys/filedesc.h> 62 #include <sys/filio.h> 63 #include <sys/fnv_hash.h> 64 #include <sys/kernel.h> 65 #include <sys/limits.h> 66 #include <sys/uio.h> 67 #include <sys/signal.h> 68 #include <sys/jail.h> 69 #include <sys/ktrace.h> 70 #include <sys/lock.h> 71 #include <sys/malloc.h> 72 #include <sys/mman.h> 73 #include <sys/mutex.h> 74 #include <sys/priv.h> 75 #include <sys/proc.h> 76 #include <sys/refcount.h> 77 #include <sys/resourcevar.h> 78 #include <sys/rwlock.h> 79 #include <sys/sbuf.h> 80 #include <sys/stat.h> 81 #include <sys/syscallsubr.h> 82 #include <sys/sysctl.h> 83 #include <sys/sysproto.h> 84 #include <sys/systm.h> 85 #include <sys/sx.h> 86 #include <sys/time.h> 87 #include <sys/vmmeter.h> 88 #include <sys/vnode.h> 89 #include <sys/unistd.h> 90 #include <sys/user.h> 91 92 #include <security/audit/audit.h> 93 #include <security/mac/mac_framework.h> 94 95 #include <vm/vm.h> 96 #include <vm/vm_param.h> 97 #include <vm/pmap.h> 98 #include <vm/vm_extern.h> 99 #include <vm/vm_map.h> 100 #include <vm/vm_kern.h> 101 #include <vm/vm_object.h> 102 #include <vm/vm_page.h> 103 #include <vm/vm_pageout.h> 104 #include <vm/vm_pager.h> 105 #include <vm/swap_pager.h> 106 107 struct shm_mapping { 108 char *sm_path; 109 Fnv32_t sm_fnv; 110 struct shmfd *sm_shmfd; 111 LIST_ENTRY(shm_mapping) sm_link; 112 }; 113 114 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 115 static LIST_HEAD(, shm_mapping) *shm_dictionary; 116 static struct sx shm_dict_lock; 117 static struct mtx shm_timestamp_lock; 118 static u_long shm_hash; 119 static struct unrhdr64 shm_ino_unr; 120 static dev_t shm_dev_ino; 121 122 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 123 124 static void shm_init(void *arg); 125 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 126 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 127 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 128 static void shm_doremove(struct shm_mapping *map); 129 static int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 130 void *rl_cookie); 131 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 132 void *rl_cookie); 133 static int shm_copyin_path(struct thread *td, const char *userpath_in, 134 char **path_out); 135 static int shm_deallocate(struct shmfd *shmfd, off_t *offset, 136 off_t *length, int flags); 137 138 static fo_rdwr_t shm_read; 139 static fo_rdwr_t shm_write; 140 static fo_truncate_t shm_truncate; 141 static fo_ioctl_t shm_ioctl; 142 static fo_stat_t shm_stat; 143 static fo_close_t shm_close; 144 static fo_chmod_t shm_chmod; 145 static fo_chown_t shm_chown; 146 static fo_seek_t shm_seek; 147 static fo_fill_kinfo_t shm_fill_kinfo; 148 static fo_mmap_t shm_mmap; 149 static fo_get_seals_t shm_get_seals; 150 static fo_add_seals_t shm_add_seals; 151 static fo_fallocate_t shm_fallocate; 152 static fo_fspacectl_t shm_fspacectl; 153 154 /* File descriptor operations. */ 155 struct fileops shm_ops = { 156 .fo_read = shm_read, 157 .fo_write = shm_write, 158 .fo_truncate = shm_truncate, 159 .fo_ioctl = shm_ioctl, 160 .fo_poll = invfo_poll, 161 .fo_kqfilter = invfo_kqfilter, 162 .fo_stat = shm_stat, 163 .fo_close = shm_close, 164 .fo_chmod = shm_chmod, 165 .fo_chown = shm_chown, 166 .fo_sendfile = vn_sendfile, 167 .fo_seek = shm_seek, 168 .fo_fill_kinfo = shm_fill_kinfo, 169 .fo_mmap = shm_mmap, 170 .fo_get_seals = shm_get_seals, 171 .fo_add_seals = shm_add_seals, 172 .fo_fallocate = shm_fallocate, 173 .fo_fspacectl = shm_fspacectl, 174 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 175 }; 176 177 FEATURE(posix_shm, "POSIX shared memory"); 178 179 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 180 ""); 181 182 static int largepage_reclaim_tries = 1; 183 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 184 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 185 "Number of contig reclaims before giving up for default alloc policy"); 186 187 static int 188 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 189 { 190 vm_page_t m; 191 vm_pindex_t idx; 192 size_t tlen; 193 int error, offset, rv; 194 195 idx = OFF_TO_IDX(uio->uio_offset); 196 offset = uio->uio_offset & PAGE_MASK; 197 tlen = MIN(PAGE_SIZE - offset, len); 198 199 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 200 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 201 if (rv == VM_PAGER_OK) 202 goto found; 203 204 /* 205 * Read I/O without either a corresponding resident page or swap 206 * page: use zero_region. This is intended to avoid instantiating 207 * pages on read from a sparse region. 208 */ 209 VM_OBJECT_WLOCK(obj); 210 m = vm_page_lookup(obj, idx); 211 if (uio->uio_rw == UIO_READ && m == NULL && 212 !vm_pager_has_page(obj, idx, NULL, NULL)) { 213 VM_OBJECT_WUNLOCK(obj); 214 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 215 } 216 217 /* 218 * Although the tmpfs vnode lock is held here, it is 219 * nonetheless safe to sleep waiting for a free page. The 220 * pageout daemon does not need to acquire the tmpfs vnode 221 * lock to page out tobj's pages because tobj is a OBJT_SWAP 222 * type object. 223 */ 224 rv = vm_page_grab_valid(&m, obj, idx, 225 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 226 if (rv != VM_PAGER_OK) { 227 VM_OBJECT_WUNLOCK(obj); 228 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 229 obj, idx, rv); 230 return (EIO); 231 } 232 VM_OBJECT_WUNLOCK(obj); 233 234 found: 235 error = uiomove_fromphys(&m, offset, tlen, uio); 236 if (uio->uio_rw == UIO_WRITE && error == 0) 237 vm_page_set_dirty(m); 238 vm_page_activate(m); 239 vm_page_sunbusy(m); 240 241 return (error); 242 } 243 244 int 245 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 246 { 247 ssize_t resid; 248 size_t len; 249 int error; 250 251 error = 0; 252 while ((resid = uio->uio_resid) > 0) { 253 if (obj_size <= uio->uio_offset) 254 break; 255 len = MIN(obj_size - uio->uio_offset, resid); 256 if (len == 0) 257 break; 258 error = uiomove_object_page(obj, len, uio); 259 if (error != 0 || resid == uio->uio_resid) 260 break; 261 } 262 return (error); 263 } 264 265 static u_long count_largepages[MAXPAGESIZES]; 266 267 static int 268 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 269 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 270 { 271 vm_page_t m __diagused; 272 int psind; 273 274 psind = object->un_pager.phys.data_val; 275 if (psind == 0 || pidx >= object->size) 276 return (VM_PAGER_FAIL); 277 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 278 279 /* 280 * We only busy the first page in the superpage run. It is 281 * useless to busy whole run since we only remove full 282 * superpage, and it takes too long to busy e.g. 512 * 512 == 283 * 262144 pages constituing 1G amd64 superage. 284 */ 285 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 286 MPASS(m != NULL); 287 288 *last = *first + atop(pagesizes[psind]) - 1; 289 return (VM_PAGER_OK); 290 } 291 292 static boolean_t 293 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 294 int *before, int *after) 295 { 296 int psind; 297 298 psind = object->un_pager.phys.data_val; 299 if (psind == 0 || pindex >= object->size) 300 return (FALSE); 301 if (before != NULL) { 302 *before = pindex - rounddown2(pindex, pagesizes[psind] / 303 PAGE_SIZE); 304 } 305 if (after != NULL) { 306 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 307 pindex; 308 } 309 return (TRUE); 310 } 311 312 static void 313 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 314 vm_ooffset_t foff, struct ucred *cred) 315 { 316 } 317 318 static void 319 shm_largepage_phys_dtor(vm_object_t object) 320 { 321 int psind; 322 323 psind = object->un_pager.phys.data_val; 324 if (psind != 0) { 325 atomic_subtract_long(&count_largepages[psind], 326 object->size / (pagesizes[psind] / PAGE_SIZE)); 327 vm_wire_sub(object->size); 328 } else { 329 KASSERT(object->size == 0, 330 ("largepage phys obj %p not initialized bit size %#jx > 0", 331 object, (uintmax_t)object->size)); 332 } 333 } 334 335 static const struct phys_pager_ops shm_largepage_phys_ops = { 336 .phys_pg_populate = shm_largepage_phys_populate, 337 .phys_pg_haspage = shm_largepage_phys_haspage, 338 .phys_pg_ctor = shm_largepage_phys_ctor, 339 .phys_pg_dtor = shm_largepage_phys_dtor, 340 }; 341 342 bool 343 shm_largepage(struct shmfd *shmfd) 344 { 345 return (shmfd->shm_object->type == OBJT_PHYS); 346 } 347 348 static int 349 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 350 { 351 struct shmfd *shmfd; 352 off_t foffset; 353 int error; 354 355 shmfd = fp->f_data; 356 foffset = foffset_lock(fp, 0); 357 error = 0; 358 switch (whence) { 359 case L_INCR: 360 if (foffset < 0 || 361 (offset > 0 && foffset > OFF_MAX - offset)) { 362 error = EOVERFLOW; 363 break; 364 } 365 offset += foffset; 366 break; 367 case L_XTND: 368 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 369 error = EOVERFLOW; 370 break; 371 } 372 offset += shmfd->shm_size; 373 break; 374 case L_SET: 375 break; 376 default: 377 error = EINVAL; 378 } 379 if (error == 0) { 380 if (offset < 0 || offset > shmfd->shm_size) 381 error = EINVAL; 382 else 383 td->td_uretoff.tdu_off = offset; 384 } 385 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 386 return (error); 387 } 388 389 static int 390 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 391 int flags, struct thread *td) 392 { 393 struct shmfd *shmfd; 394 void *rl_cookie; 395 int error; 396 397 shmfd = fp->f_data; 398 #ifdef MAC 399 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 400 if (error) 401 return (error); 402 #endif 403 foffset_lock_uio(fp, uio, flags); 404 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 405 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 406 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 407 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 408 foffset_unlock_uio(fp, uio, flags); 409 return (error); 410 } 411 412 static int 413 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 414 int flags, struct thread *td) 415 { 416 struct shmfd *shmfd; 417 void *rl_cookie; 418 int error; 419 off_t size; 420 421 shmfd = fp->f_data; 422 #ifdef MAC 423 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 424 if (error) 425 return (error); 426 #endif 427 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 428 return (EINVAL); 429 foffset_lock_uio(fp, uio, flags); 430 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 431 /* 432 * Overflow is only an error if we're supposed to expand on 433 * write. Otherwise, we'll just truncate the write to the 434 * size of the file, which can only grow up to OFF_MAX. 435 */ 436 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 437 foffset_unlock_uio(fp, uio, flags); 438 return (EFBIG); 439 } 440 441 size = shmfd->shm_size; 442 } else { 443 size = uio->uio_offset + uio->uio_resid; 444 } 445 if ((flags & FOF_OFFSET) == 0) { 446 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 447 &shmfd->shm_mtx); 448 } else { 449 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 450 size, &shmfd->shm_mtx); 451 } 452 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 453 error = EPERM; 454 } else { 455 error = 0; 456 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 457 size > shmfd->shm_size) { 458 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 459 } 460 if (error == 0) 461 error = uiomove_object(shmfd->shm_object, 462 shmfd->shm_size, uio); 463 } 464 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 465 foffset_unlock_uio(fp, uio, flags); 466 return (error); 467 } 468 469 static int 470 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 471 struct thread *td) 472 { 473 struct shmfd *shmfd; 474 #ifdef MAC 475 int error; 476 #endif 477 478 shmfd = fp->f_data; 479 #ifdef MAC 480 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 481 if (error) 482 return (error); 483 #endif 484 return (shm_dotruncate(shmfd, length)); 485 } 486 487 int 488 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 489 struct thread *td) 490 { 491 struct shmfd *shmfd; 492 struct shm_largepage_conf *conf; 493 void *rl_cookie; 494 495 shmfd = fp->f_data; 496 switch (com) { 497 case FIONBIO: 498 case FIOASYNC: 499 /* 500 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 501 * just like it would on an unlinked regular file 502 */ 503 return (0); 504 case FIOSSHMLPGCNF: 505 if (!shm_largepage(shmfd)) 506 return (ENOTTY); 507 conf = data; 508 if (shmfd->shm_lp_psind != 0 && 509 conf->psind != shmfd->shm_lp_psind) 510 return (EINVAL); 511 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 512 pagesizes[conf->psind] == 0) 513 return (EINVAL); 514 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 515 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 516 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 517 return (EINVAL); 518 519 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 520 &shmfd->shm_mtx); 521 shmfd->shm_lp_psind = conf->psind; 522 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 523 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 524 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 525 return (0); 526 case FIOGSHMLPGCNF: 527 if (!shm_largepage(shmfd)) 528 return (ENOTTY); 529 conf = data; 530 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX, 531 &shmfd->shm_mtx); 532 conf->psind = shmfd->shm_lp_psind; 533 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 534 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 535 return (0); 536 default: 537 return (ENOTTY); 538 } 539 } 540 541 static int 542 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred) 543 { 544 struct shmfd *shmfd; 545 #ifdef MAC 546 int error; 547 #endif 548 549 shmfd = fp->f_data; 550 551 #ifdef MAC 552 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 553 if (error) 554 return (error); 555 #endif 556 557 /* 558 * Attempt to return sanish values for fstat() on a memory file 559 * descriptor. 560 */ 561 bzero(sb, sizeof(*sb)); 562 sb->st_blksize = PAGE_SIZE; 563 sb->st_size = shmfd->shm_size; 564 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 565 mtx_lock(&shm_timestamp_lock); 566 sb->st_atim = shmfd->shm_atime; 567 sb->st_ctim = shmfd->shm_ctime; 568 sb->st_mtim = shmfd->shm_mtime; 569 sb->st_birthtim = shmfd->shm_birthtime; 570 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 571 sb->st_uid = shmfd->shm_uid; 572 sb->st_gid = shmfd->shm_gid; 573 mtx_unlock(&shm_timestamp_lock); 574 sb->st_dev = shm_dev_ino; 575 sb->st_ino = shmfd->shm_ino; 576 sb->st_nlink = shmfd->shm_object->ref_count; 577 sb->st_blocks = shmfd->shm_object->size / 578 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 579 580 return (0); 581 } 582 583 static int 584 shm_close(struct file *fp, struct thread *td) 585 { 586 struct shmfd *shmfd; 587 588 shmfd = fp->f_data; 589 fp->f_data = NULL; 590 shm_drop(shmfd); 591 592 return (0); 593 } 594 595 static int 596 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 597 int error; 598 char *path; 599 const char *pr_path; 600 size_t pr_pathlen; 601 602 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 603 pr_path = td->td_ucred->cr_prison->pr_path; 604 605 /* Construct a full pathname for jailed callers. */ 606 pr_pathlen = strcmp(pr_path, "/") == 607 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 608 error = copyinstr(userpath_in, path + pr_pathlen, 609 MAXPATHLEN - pr_pathlen, NULL); 610 if (error != 0) 611 goto out; 612 613 #ifdef KTRACE 614 if (KTRPOINT(curthread, KTR_NAMEI)) 615 ktrnamei(path); 616 #endif 617 618 /* Require paths to start with a '/' character. */ 619 if (path[pr_pathlen] != '/') { 620 error = EINVAL; 621 goto out; 622 } 623 624 *path_out = path; 625 626 out: 627 if (error != 0) 628 free(path, M_SHMFD); 629 630 return (error); 631 } 632 633 static int 634 shm_partial_page_invalidate(vm_object_t object, vm_pindex_t idx, int base, 635 int end) 636 { 637 vm_page_t m; 638 int rv; 639 640 VM_OBJECT_ASSERT_WLOCKED(object); 641 KASSERT(base >= 0, ("%s: base %d", __func__, base)); 642 KASSERT(end - base <= PAGE_SIZE, ("%s: base %d end %d", __func__, base, 643 end)); 644 645 retry: 646 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 647 if (m != NULL) { 648 MPASS(vm_page_all_valid(m)); 649 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 650 m = vm_page_alloc(object, idx, 651 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 652 if (m == NULL) 653 goto retry; 654 vm_object_pip_add(object, 1); 655 VM_OBJECT_WUNLOCK(object); 656 rv = vm_pager_get_pages(object, &m, 1, NULL, NULL); 657 VM_OBJECT_WLOCK(object); 658 vm_object_pip_wakeup(object); 659 if (rv == VM_PAGER_OK) { 660 /* 661 * Since the page was not resident, and therefore not 662 * recently accessed, immediately enqueue it for 663 * asynchronous laundering. The current operation is 664 * not regarded as an access. 665 */ 666 vm_page_launder(m); 667 } else { 668 vm_page_free(m); 669 VM_OBJECT_WUNLOCK(object); 670 return (EIO); 671 } 672 } 673 if (m != NULL) { 674 pmap_zero_page_area(m, base, end - base); 675 KASSERT(vm_page_all_valid(m), ("%s: page %p is invalid", 676 __func__, m)); 677 vm_page_set_dirty(m); 678 vm_page_xunbusy(m); 679 } 680 681 return (0); 682 } 683 684 static int 685 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 686 { 687 vm_object_t object; 688 vm_pindex_t nobjsize; 689 vm_ooffset_t delta; 690 int base, error; 691 692 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 693 object = shmfd->shm_object; 694 VM_OBJECT_ASSERT_WLOCKED(object); 695 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 696 if (length == shmfd->shm_size) 697 return (0); 698 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 699 700 /* Are we shrinking? If so, trim the end. */ 701 if (length < shmfd->shm_size) { 702 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 703 return (EPERM); 704 705 /* 706 * Disallow any requests to shrink the size if this 707 * object is mapped into the kernel. 708 */ 709 if (shmfd->shm_kmappings > 0) 710 return (EBUSY); 711 712 /* 713 * Zero the truncated part of the last page. 714 */ 715 base = length & PAGE_MASK; 716 if (base != 0) { 717 error = shm_partial_page_invalidate(object, 718 OFF_TO_IDX(length), base, PAGE_SIZE); 719 if (error) 720 return (error); 721 } 722 delta = IDX_TO_OFF(object->size - nobjsize); 723 724 if (nobjsize < object->size) 725 vm_object_page_remove(object, nobjsize, object->size, 726 0); 727 728 /* Free the swap accounted for shm */ 729 swap_release_by_cred(delta, object->cred); 730 object->charge -= delta; 731 } else { 732 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 733 return (EPERM); 734 735 /* Try to reserve additional swap space. */ 736 delta = IDX_TO_OFF(nobjsize - object->size); 737 if (!swap_reserve_by_cred(delta, object->cred)) 738 return (ENOMEM); 739 object->charge += delta; 740 } 741 shmfd->shm_size = length; 742 mtx_lock(&shm_timestamp_lock); 743 vfs_timestamp(&shmfd->shm_ctime); 744 shmfd->shm_mtime = shmfd->shm_ctime; 745 mtx_unlock(&shm_timestamp_lock); 746 object->size = nobjsize; 747 return (0); 748 } 749 750 static int 751 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 752 { 753 vm_object_t object; 754 vm_page_t m; 755 vm_pindex_t newobjsz; 756 vm_pindex_t oldobjsz __unused; 757 int aflags, error, i, psind, try; 758 759 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 760 object = shmfd->shm_object; 761 VM_OBJECT_ASSERT_WLOCKED(object); 762 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 763 764 oldobjsz = object->size; 765 newobjsz = OFF_TO_IDX(length); 766 if (length == shmfd->shm_size) 767 return (0); 768 psind = shmfd->shm_lp_psind; 769 if (psind == 0 && length != 0) 770 return (EINVAL); 771 if ((length & (pagesizes[psind] - 1)) != 0) 772 return (EINVAL); 773 774 if (length < shmfd->shm_size) { 775 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 776 return (EPERM); 777 if (shmfd->shm_kmappings > 0) 778 return (EBUSY); 779 return (ENOTSUP); /* Pages are unmanaged. */ 780 #if 0 781 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 782 object->size = newobjsz; 783 shmfd->shm_size = length; 784 return (0); 785 #endif 786 } 787 788 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 789 return (EPERM); 790 791 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 792 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 793 aflags |= VM_ALLOC_WAITFAIL; 794 try = 0; 795 796 /* 797 * Extend shmfd and object, keeping all already fully 798 * allocated large pages intact even on error, because dropped 799 * object lock might allowed mapping of them. 800 */ 801 while (object->size < newobjsz) { 802 m = vm_page_alloc_contig(object, object->size, aflags, 803 pagesizes[psind] / PAGE_SIZE, 0, ~0, 804 pagesizes[psind], 0, 805 VM_MEMATTR_DEFAULT); 806 if (m == NULL) { 807 VM_OBJECT_WUNLOCK(object); 808 if (shmfd->shm_lp_alloc_policy == 809 SHM_LARGEPAGE_ALLOC_NOWAIT || 810 (shmfd->shm_lp_alloc_policy == 811 SHM_LARGEPAGE_ALLOC_DEFAULT && 812 try >= largepage_reclaim_tries)) { 813 VM_OBJECT_WLOCK(object); 814 return (ENOMEM); 815 } 816 error = vm_page_reclaim_contig(aflags, 817 pagesizes[psind] / PAGE_SIZE, 0, ~0, 818 pagesizes[psind], 0) ? 0 : 819 vm_wait_intr(object); 820 if (error != 0) { 821 VM_OBJECT_WLOCK(object); 822 return (error); 823 } 824 try++; 825 VM_OBJECT_WLOCK(object); 826 continue; 827 } 828 try = 0; 829 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 830 if ((m[i].flags & PG_ZERO) == 0) 831 pmap_zero_page(&m[i]); 832 vm_page_valid(&m[i]); 833 vm_page_xunbusy(&m[i]); 834 } 835 object->size += OFF_TO_IDX(pagesizes[psind]); 836 shmfd->shm_size += pagesizes[psind]; 837 atomic_add_long(&count_largepages[psind], 1); 838 vm_wire_add(atop(pagesizes[psind])); 839 } 840 return (0); 841 } 842 843 static int 844 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 845 { 846 int error; 847 848 VM_OBJECT_WLOCK(shmfd->shm_object); 849 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 850 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 851 rl_cookie); 852 VM_OBJECT_WUNLOCK(shmfd->shm_object); 853 return (error); 854 } 855 856 int 857 shm_dotruncate(struct shmfd *shmfd, off_t length) 858 { 859 void *rl_cookie; 860 int error; 861 862 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 863 &shmfd->shm_mtx); 864 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 865 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 866 return (error); 867 } 868 869 /* 870 * shmfd object management including creation and reference counting 871 * routines. 872 */ 873 struct shmfd * 874 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 875 { 876 struct shmfd *shmfd; 877 878 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 879 shmfd->shm_size = 0; 880 shmfd->shm_uid = ucred->cr_uid; 881 shmfd->shm_gid = ucred->cr_gid; 882 shmfd->shm_mode = mode; 883 if (largepage) { 884 shmfd->shm_object = phys_pager_allocate(NULL, 885 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 886 VM_PROT_DEFAULT, 0, ucred); 887 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 888 } else { 889 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 890 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 891 } 892 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 893 vfs_timestamp(&shmfd->shm_birthtime); 894 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 895 shmfd->shm_birthtime; 896 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 897 refcount_init(&shmfd->shm_refs, 1); 898 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 899 rangelock_init(&shmfd->shm_rl); 900 #ifdef MAC 901 mac_posixshm_init(shmfd); 902 mac_posixshm_create(ucred, shmfd); 903 #endif 904 905 return (shmfd); 906 } 907 908 struct shmfd * 909 shm_hold(struct shmfd *shmfd) 910 { 911 912 refcount_acquire(&shmfd->shm_refs); 913 return (shmfd); 914 } 915 916 void 917 shm_drop(struct shmfd *shmfd) 918 { 919 920 if (refcount_release(&shmfd->shm_refs)) { 921 #ifdef MAC 922 mac_posixshm_destroy(shmfd); 923 #endif 924 rangelock_destroy(&shmfd->shm_rl); 925 mtx_destroy(&shmfd->shm_mtx); 926 vm_object_deallocate(shmfd->shm_object); 927 free(shmfd, M_SHMFD); 928 } 929 } 930 931 /* 932 * Determine if the credentials have sufficient permissions for a 933 * specified combination of FREAD and FWRITE. 934 */ 935 int 936 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 937 { 938 accmode_t accmode; 939 int error; 940 941 accmode = 0; 942 if (flags & FREAD) 943 accmode |= VREAD; 944 if (flags & FWRITE) 945 accmode |= VWRITE; 946 mtx_lock(&shm_timestamp_lock); 947 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 948 accmode, ucred); 949 mtx_unlock(&shm_timestamp_lock); 950 return (error); 951 } 952 953 static void 954 shm_init(void *arg) 955 { 956 char name[32]; 957 int i; 958 959 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 960 sx_init(&shm_dict_lock, "shm dictionary"); 961 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 962 new_unrhdr64(&shm_ino_unr, 1); 963 shm_dev_ino = devfs_alloc_cdp_inode(); 964 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 965 966 for (i = 1; i < MAXPAGESIZES; i++) { 967 if (pagesizes[i] == 0) 968 break; 969 #define M (1024 * 1024) 970 #define G (1024 * M) 971 if (pagesizes[i] >= G) 972 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 973 else if (pagesizes[i] >= M) 974 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 975 else 976 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 977 #undef G 978 #undef M 979 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 980 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 981 "number of non-transient largepages allocated"); 982 } 983 } 984 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 985 986 /* 987 * Remove all shared memory objects that belong to a prison. 988 */ 989 void 990 shm_remove_prison(struct prison *pr) 991 { 992 struct shm_mapping *shmm, *tshmm; 993 u_long i; 994 995 sx_xlock(&shm_dict_lock); 996 for (i = 0; i < shm_hash + 1; i++) { 997 LIST_FOREACH_SAFE(shmm, &shm_dictionary[i], sm_link, tshmm) { 998 if (shmm->sm_shmfd->shm_object->cred && 999 shmm->sm_shmfd->shm_object->cred->cr_prison == pr) 1000 shm_doremove(shmm); 1001 } 1002 } 1003 sx_xunlock(&shm_dict_lock); 1004 } 1005 1006 /* 1007 * Dictionary management. We maintain an in-kernel dictionary to map 1008 * paths to shmfd objects. We use the FNV hash on the path to store 1009 * the mappings in a hash table. 1010 */ 1011 static struct shmfd * 1012 shm_lookup(char *path, Fnv32_t fnv) 1013 { 1014 struct shm_mapping *map; 1015 1016 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1017 if (map->sm_fnv != fnv) 1018 continue; 1019 if (strcmp(map->sm_path, path) == 0) 1020 return (map->sm_shmfd); 1021 } 1022 1023 return (NULL); 1024 } 1025 1026 static void 1027 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 1028 { 1029 struct shm_mapping *map; 1030 1031 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 1032 map->sm_path = path; 1033 map->sm_fnv = fnv; 1034 map->sm_shmfd = shm_hold(shmfd); 1035 shmfd->shm_path = path; 1036 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 1037 } 1038 1039 static int 1040 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1041 { 1042 struct shm_mapping *map; 1043 int error; 1044 1045 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1046 if (map->sm_fnv != fnv) 1047 continue; 1048 if (strcmp(map->sm_path, path) == 0) { 1049 #ifdef MAC 1050 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1051 if (error) 1052 return (error); 1053 #endif 1054 error = shm_access(map->sm_shmfd, ucred, 1055 FREAD | FWRITE); 1056 if (error) 1057 return (error); 1058 shm_doremove(map); 1059 return (0); 1060 } 1061 } 1062 1063 return (ENOENT); 1064 } 1065 1066 static void 1067 shm_doremove(struct shm_mapping *map) 1068 { 1069 map->sm_shmfd->shm_path = NULL; 1070 LIST_REMOVE(map, sm_link); 1071 shm_drop(map->sm_shmfd); 1072 free(map->sm_path, M_SHMFD); 1073 free(map, M_SHMFD); 1074 } 1075 1076 int 1077 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1078 int shmflags, struct filecaps *fcaps, const char *name __unused) 1079 { 1080 struct pwddesc *pdp; 1081 struct shmfd *shmfd; 1082 struct file *fp; 1083 char *path; 1084 void *rl_cookie; 1085 Fnv32_t fnv; 1086 mode_t cmode; 1087 int error, fd, initial_seals; 1088 bool largepage; 1089 1090 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1091 SHM_LARGEPAGE)) != 0) 1092 return (EINVAL); 1093 1094 initial_seals = F_SEAL_SEAL; 1095 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1096 initial_seals &= ~F_SEAL_SEAL; 1097 1098 #ifdef CAPABILITY_MODE 1099 /* 1100 * shm_open(2) is only allowed for anonymous objects. 1101 */ 1102 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1103 return (ECAPMODE); 1104 #endif 1105 1106 AUDIT_ARG_FFLAGS(flags); 1107 AUDIT_ARG_MODE(mode); 1108 1109 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1110 return (EINVAL); 1111 1112 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1113 return (EINVAL); 1114 1115 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1116 if (largepage && !PMAP_HAS_LARGEPAGES) 1117 return (ENOTTY); 1118 1119 /* 1120 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1121 * If the decision is made later to allow additional seals, care must be 1122 * taken below to ensure that the seals are properly set if the shmfd 1123 * already existed -- this currently assumes that only F_SEAL_SEAL can 1124 * be set and doesn't take further precautions to ensure the validity of 1125 * the seals being added with respect to current mappings. 1126 */ 1127 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1128 return (EINVAL); 1129 1130 pdp = td->td_proc->p_pd; 1131 cmode = (mode & ~pdp->pd_cmask) & ACCESSPERMS; 1132 1133 /* 1134 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1135 * by POSIX. We allow it to be unset here so that an in-kernel 1136 * interface may be written as a thin layer around shm, optionally not 1137 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1138 * in sys_shm_open() to keep this implementation compliant. 1139 */ 1140 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1141 if (error) 1142 return (error); 1143 1144 /* A SHM_ANON path pointer creates an anonymous object. */ 1145 if (userpath == SHM_ANON) { 1146 /* A read-only anonymous object is pointless. */ 1147 if ((flags & O_ACCMODE) == O_RDONLY) { 1148 fdclose(td, fp, fd); 1149 fdrop(fp, td); 1150 return (EINVAL); 1151 } 1152 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1153 shmfd->shm_seals = initial_seals; 1154 shmfd->shm_flags = shmflags; 1155 } else { 1156 error = shm_copyin_path(td, userpath, &path); 1157 if (error != 0) { 1158 fdclose(td, fp, fd); 1159 fdrop(fp, td); 1160 return (error); 1161 } 1162 1163 AUDIT_ARG_UPATH1_CANON(path); 1164 fnv = fnv_32_str(path, FNV1_32_INIT); 1165 sx_xlock(&shm_dict_lock); 1166 shmfd = shm_lookup(path, fnv); 1167 if (shmfd == NULL) { 1168 /* Object does not yet exist, create it if requested. */ 1169 if (flags & O_CREAT) { 1170 #ifdef MAC 1171 error = mac_posixshm_check_create(td->td_ucred, 1172 path); 1173 if (error == 0) { 1174 #endif 1175 shmfd = shm_alloc(td->td_ucred, cmode, 1176 largepage); 1177 shmfd->shm_seals = initial_seals; 1178 shmfd->shm_flags = shmflags; 1179 shm_insert(path, fnv, shmfd); 1180 #ifdef MAC 1181 } 1182 #endif 1183 } else { 1184 free(path, M_SHMFD); 1185 error = ENOENT; 1186 } 1187 } else { 1188 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1189 &shmfd->shm_mtx); 1190 1191 /* 1192 * kern_shm_open() likely shouldn't ever error out on 1193 * trying to set a seal that already exists, unlike 1194 * F_ADD_SEALS. This would break terribly as 1195 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1196 * historical behavior where the underlying file could 1197 * not be sealed. 1198 */ 1199 initial_seals &= ~shmfd->shm_seals; 1200 1201 /* 1202 * Object already exists, obtain a new 1203 * reference if requested and permitted. 1204 */ 1205 free(path, M_SHMFD); 1206 1207 /* 1208 * initial_seals can't set additional seals if we've 1209 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1210 * then we've already removed that one from 1211 * initial_seals. This is currently redundant as we 1212 * only allow setting F_SEAL_SEAL at creation time, but 1213 * it's cheap to check and decreases the effort required 1214 * to allow additional seals. 1215 */ 1216 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1217 initial_seals != 0) 1218 error = EPERM; 1219 else if ((flags & (O_CREAT | O_EXCL)) == 1220 (O_CREAT | O_EXCL)) 1221 error = EEXIST; 1222 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1223 error = EINVAL; 1224 else { 1225 #ifdef MAC 1226 error = mac_posixshm_check_open(td->td_ucred, 1227 shmfd, FFLAGS(flags & O_ACCMODE)); 1228 if (error == 0) 1229 #endif 1230 error = shm_access(shmfd, td->td_ucred, 1231 FFLAGS(flags & O_ACCMODE)); 1232 } 1233 1234 /* 1235 * Truncate the file back to zero length if 1236 * O_TRUNC was specified and the object was 1237 * opened with read/write. 1238 */ 1239 if (error == 0 && 1240 (flags & (O_ACCMODE | O_TRUNC)) == 1241 (O_RDWR | O_TRUNC)) { 1242 VM_OBJECT_WLOCK(shmfd->shm_object); 1243 #ifdef MAC 1244 error = mac_posixshm_check_truncate( 1245 td->td_ucred, fp->f_cred, shmfd); 1246 if (error == 0) 1247 #endif 1248 error = shm_dotruncate_locked(shmfd, 0, 1249 rl_cookie); 1250 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1251 } 1252 if (error == 0) { 1253 /* 1254 * Currently we only allow F_SEAL_SEAL to be 1255 * set initially. As noted above, this would 1256 * need to be reworked should that change. 1257 */ 1258 shmfd->shm_seals |= initial_seals; 1259 shm_hold(shmfd); 1260 } 1261 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 1262 &shmfd->shm_mtx); 1263 } 1264 sx_xunlock(&shm_dict_lock); 1265 1266 if (error) { 1267 fdclose(td, fp, fd); 1268 fdrop(fp, td); 1269 return (error); 1270 } 1271 } 1272 1273 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1274 1275 td->td_retval[0] = fd; 1276 fdrop(fp, td); 1277 1278 return (0); 1279 } 1280 1281 /* System calls. */ 1282 #ifdef COMPAT_FREEBSD12 1283 int 1284 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1285 { 1286 1287 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1288 uap->mode, NULL)); 1289 } 1290 #endif 1291 1292 int 1293 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1294 { 1295 char *path; 1296 Fnv32_t fnv; 1297 int error; 1298 1299 error = shm_copyin_path(td, uap->path, &path); 1300 if (error != 0) 1301 return (error); 1302 1303 AUDIT_ARG_UPATH1_CANON(path); 1304 fnv = fnv_32_str(path, FNV1_32_INIT); 1305 sx_xlock(&shm_dict_lock); 1306 error = shm_remove(path, fnv, td->td_ucred); 1307 sx_xunlock(&shm_dict_lock); 1308 free(path, M_SHMFD); 1309 1310 return (error); 1311 } 1312 1313 int 1314 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1315 { 1316 char *path_from = NULL, *path_to = NULL; 1317 Fnv32_t fnv_from, fnv_to; 1318 struct shmfd *fd_from; 1319 struct shmfd *fd_to; 1320 int error; 1321 int flags; 1322 1323 flags = uap->flags; 1324 AUDIT_ARG_FFLAGS(flags); 1325 1326 /* 1327 * Make sure the user passed only valid flags. 1328 * If you add a new flag, please add a new term here. 1329 */ 1330 if ((flags & ~( 1331 SHM_RENAME_NOREPLACE | 1332 SHM_RENAME_EXCHANGE 1333 )) != 0) { 1334 error = EINVAL; 1335 goto out; 1336 } 1337 1338 /* 1339 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1340 * force the user to choose one or the other. 1341 */ 1342 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1343 (flags & SHM_RENAME_EXCHANGE) != 0) { 1344 error = EINVAL; 1345 goto out; 1346 } 1347 1348 /* Renaming to or from anonymous makes no sense */ 1349 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1350 error = EINVAL; 1351 goto out; 1352 } 1353 1354 error = shm_copyin_path(td, uap->path_from, &path_from); 1355 if (error != 0) 1356 goto out; 1357 1358 error = shm_copyin_path(td, uap->path_to, &path_to); 1359 if (error != 0) 1360 goto out; 1361 1362 AUDIT_ARG_UPATH1_CANON(path_from); 1363 AUDIT_ARG_UPATH2_CANON(path_to); 1364 1365 /* Rename with from/to equal is a no-op */ 1366 if (strcmp(path_from, path_to) == 0) 1367 goto out; 1368 1369 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1370 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1371 1372 sx_xlock(&shm_dict_lock); 1373 1374 fd_from = shm_lookup(path_from, fnv_from); 1375 if (fd_from == NULL) { 1376 error = ENOENT; 1377 goto out_locked; 1378 } 1379 1380 fd_to = shm_lookup(path_to, fnv_to); 1381 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1382 error = EEXIST; 1383 goto out_locked; 1384 } 1385 1386 /* 1387 * Unconditionally prevents shm_remove from invalidating the 'from' 1388 * shm's state. 1389 */ 1390 shm_hold(fd_from); 1391 error = shm_remove(path_from, fnv_from, td->td_ucred); 1392 1393 /* 1394 * One of my assumptions failed if ENOENT (e.g. locking didn't 1395 * protect us) 1396 */ 1397 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1398 path_from)); 1399 if (error != 0) { 1400 shm_drop(fd_from); 1401 goto out_locked; 1402 } 1403 1404 /* 1405 * If we are exchanging, we need to ensure the shm_remove below 1406 * doesn't invalidate the dest shm's state. 1407 */ 1408 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1409 shm_hold(fd_to); 1410 1411 /* 1412 * NOTE: if path_to is not already in the hash, c'est la vie; 1413 * it simply means we have nothing already at path_to to unlink. 1414 * That is the ENOENT case. 1415 * 1416 * If we somehow don't have access to unlink this guy, but 1417 * did for the shm at path_from, then relink the shm to path_from 1418 * and abort with EACCES. 1419 * 1420 * All other errors: that is weird; let's relink and abort the 1421 * operation. 1422 */ 1423 error = shm_remove(path_to, fnv_to, td->td_ucred); 1424 if (error != 0 && error != ENOENT) { 1425 shm_insert(path_from, fnv_from, fd_from); 1426 shm_drop(fd_from); 1427 /* Don't free path_from now, since the hash references it */ 1428 path_from = NULL; 1429 goto out_locked; 1430 } 1431 1432 error = 0; 1433 1434 shm_insert(path_to, fnv_to, fd_from); 1435 1436 /* Don't free path_to now, since the hash references it */ 1437 path_to = NULL; 1438 1439 /* We kept a ref when we removed, and incremented again in insert */ 1440 shm_drop(fd_from); 1441 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1442 fd_from->shm_refs)); 1443 1444 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1445 shm_insert(path_from, fnv_from, fd_to); 1446 path_from = NULL; 1447 shm_drop(fd_to); 1448 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1449 fd_to->shm_refs)); 1450 } 1451 1452 out_locked: 1453 sx_xunlock(&shm_dict_lock); 1454 1455 out: 1456 free(path_from, M_SHMFD); 1457 free(path_to, M_SHMFD); 1458 return (error); 1459 } 1460 1461 static int 1462 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1463 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1464 vm_ooffset_t foff, struct thread *td) 1465 { 1466 struct vmspace *vms; 1467 vm_map_entry_t next_entry, prev_entry; 1468 vm_offset_t align, mask, maxaddr; 1469 int docow, error, rv, try; 1470 bool curmap; 1471 1472 if (shmfd->shm_lp_psind == 0) 1473 return (EINVAL); 1474 1475 /* MAP_PRIVATE is disabled */ 1476 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1477 MAP_NOCORE | 1478 #ifdef MAP_32BIT 1479 MAP_32BIT | 1480 #endif 1481 MAP_ALIGNMENT_MASK)) != 0) 1482 return (EINVAL); 1483 1484 vms = td->td_proc->p_vmspace; 1485 curmap = map == &vms->vm_map; 1486 if (curmap) { 1487 error = kern_mmap_racct_check(td, map, size); 1488 if (error != 0) 1489 return (error); 1490 } 1491 1492 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1493 docow |= MAP_INHERIT_SHARE; 1494 if ((flags & MAP_NOCORE) != 0) 1495 docow |= MAP_DISABLE_COREDUMP; 1496 1497 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1498 if ((foff & mask) != 0) 1499 return (EINVAL); 1500 maxaddr = vm_map_max(map); 1501 #ifdef MAP_32BIT 1502 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1503 maxaddr = MAP_32BIT_MAX_ADDR; 1504 #endif 1505 if (size == 0 || (size & mask) != 0 || 1506 (*addr != 0 && ((*addr & mask) != 0 || 1507 *addr + size < *addr || *addr + size > maxaddr))) 1508 return (EINVAL); 1509 1510 align = flags & MAP_ALIGNMENT_MASK; 1511 if (align == 0) { 1512 align = pagesizes[shmfd->shm_lp_psind]; 1513 } else if (align == MAP_ALIGNED_SUPER) { 1514 if (shmfd->shm_lp_psind != 1) 1515 return (EINVAL); 1516 align = pagesizes[1]; 1517 } else { 1518 align >>= MAP_ALIGNMENT_SHIFT; 1519 align = 1ULL << align; 1520 /* Also handles overflow. */ 1521 if (align < pagesizes[shmfd->shm_lp_psind]) 1522 return (EINVAL); 1523 } 1524 1525 vm_map_lock(map); 1526 if ((flags & MAP_FIXED) == 0) { 1527 try = 1; 1528 if (curmap && (*addr == 0 || 1529 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1530 *addr < round_page((vm_offset_t)vms->vm_daddr + 1531 lim_max(td, RLIMIT_DATA))))) { 1532 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1533 lim_max(td, RLIMIT_DATA), 1534 pagesizes[shmfd->shm_lp_psind]); 1535 } 1536 again: 1537 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1538 if (rv != KERN_SUCCESS) { 1539 if (try == 1) { 1540 try = 2; 1541 *addr = vm_map_min(map); 1542 if ((*addr & mask) != 0) 1543 *addr = (*addr + mask) & mask; 1544 goto again; 1545 } 1546 goto fail1; 1547 } 1548 } else if ((flags & MAP_EXCL) == 0) { 1549 rv = vm_map_delete(map, *addr, *addr + size); 1550 if (rv != KERN_SUCCESS) 1551 goto fail1; 1552 } else { 1553 error = ENOSPC; 1554 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1555 goto fail; 1556 next_entry = vm_map_entry_succ(prev_entry); 1557 if (next_entry->start < *addr + size) 1558 goto fail; 1559 } 1560 1561 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1562 prot, max_prot, docow); 1563 fail1: 1564 error = vm_mmap_to_errno(rv); 1565 fail: 1566 vm_map_unlock(map); 1567 return (error); 1568 } 1569 1570 static int 1571 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1572 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1573 vm_ooffset_t foff, struct thread *td) 1574 { 1575 struct shmfd *shmfd; 1576 vm_prot_t maxprot; 1577 int error; 1578 bool writecnt; 1579 void *rl_cookie; 1580 1581 shmfd = fp->f_data; 1582 maxprot = VM_PROT_NONE; 1583 1584 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1585 &shmfd->shm_mtx); 1586 /* FREAD should always be set. */ 1587 if ((fp->f_flag & FREAD) != 0) 1588 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1589 1590 /* 1591 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1592 * mapping with a write seal applied. Private mappings are always 1593 * writeable. 1594 */ 1595 if ((flags & MAP_SHARED) == 0) { 1596 cap_maxprot |= VM_PROT_WRITE; 1597 maxprot |= VM_PROT_WRITE; 1598 writecnt = false; 1599 } else { 1600 if ((fp->f_flag & FWRITE) != 0 && 1601 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1602 maxprot |= VM_PROT_WRITE; 1603 1604 /* 1605 * Any mappings from a writable descriptor may be upgraded to 1606 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1607 * applied between the open and subsequent mmap(2). We want to 1608 * reject application of a write seal as long as any such 1609 * mapping exists so that the seal cannot be trivially bypassed. 1610 */ 1611 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1612 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1613 error = EACCES; 1614 goto out; 1615 } 1616 } 1617 maxprot &= cap_maxprot; 1618 1619 /* See comment in vn_mmap(). */ 1620 if ( 1621 #ifdef _LP64 1622 objsize > OFF_MAX || 1623 #endif 1624 foff > OFF_MAX - objsize) { 1625 error = EINVAL; 1626 goto out; 1627 } 1628 1629 #ifdef MAC 1630 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1631 if (error != 0) 1632 goto out; 1633 #endif 1634 1635 mtx_lock(&shm_timestamp_lock); 1636 vfs_timestamp(&shmfd->shm_atime); 1637 mtx_unlock(&shm_timestamp_lock); 1638 vm_object_reference(shmfd->shm_object); 1639 1640 if (shm_largepage(shmfd)) { 1641 writecnt = false; 1642 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1643 maxprot, flags, foff, td); 1644 } else { 1645 if (writecnt) { 1646 vm_pager_update_writecount(shmfd->shm_object, 0, 1647 objsize); 1648 } 1649 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1650 shmfd->shm_object, foff, writecnt, td); 1651 } 1652 if (error != 0) { 1653 if (writecnt) 1654 vm_pager_release_writecount(shmfd->shm_object, 0, 1655 objsize); 1656 vm_object_deallocate(shmfd->shm_object); 1657 } 1658 out: 1659 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1660 return (error); 1661 } 1662 1663 static int 1664 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1665 struct thread *td) 1666 { 1667 struct shmfd *shmfd; 1668 int error; 1669 1670 error = 0; 1671 shmfd = fp->f_data; 1672 mtx_lock(&shm_timestamp_lock); 1673 /* 1674 * SUSv4 says that x bits of permission need not be affected. 1675 * Be consistent with our shm_open there. 1676 */ 1677 #ifdef MAC 1678 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1679 if (error != 0) 1680 goto out; 1681 #endif 1682 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1683 VADMIN, active_cred); 1684 if (error != 0) 1685 goto out; 1686 shmfd->shm_mode = mode & ACCESSPERMS; 1687 out: 1688 mtx_unlock(&shm_timestamp_lock); 1689 return (error); 1690 } 1691 1692 static int 1693 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1694 struct thread *td) 1695 { 1696 struct shmfd *shmfd; 1697 int error; 1698 1699 error = 0; 1700 shmfd = fp->f_data; 1701 mtx_lock(&shm_timestamp_lock); 1702 #ifdef MAC 1703 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1704 if (error != 0) 1705 goto out; 1706 #endif 1707 if (uid == (uid_t)-1) 1708 uid = shmfd->shm_uid; 1709 if (gid == (gid_t)-1) 1710 gid = shmfd->shm_gid; 1711 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1712 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1713 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1714 goto out; 1715 shmfd->shm_uid = uid; 1716 shmfd->shm_gid = gid; 1717 out: 1718 mtx_unlock(&shm_timestamp_lock); 1719 return (error); 1720 } 1721 1722 /* 1723 * Helper routines to allow the backing object of a shared memory file 1724 * descriptor to be mapped in the kernel. 1725 */ 1726 int 1727 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1728 { 1729 struct shmfd *shmfd; 1730 vm_offset_t kva, ofs; 1731 vm_object_t obj; 1732 int rv; 1733 1734 if (fp->f_type != DTYPE_SHM) 1735 return (EINVAL); 1736 shmfd = fp->f_data; 1737 obj = shmfd->shm_object; 1738 VM_OBJECT_WLOCK(obj); 1739 /* 1740 * XXXRW: This validation is probably insufficient, and subject to 1741 * sign errors. It should be fixed. 1742 */ 1743 if (offset >= shmfd->shm_size || 1744 offset + size > round_page(shmfd->shm_size)) { 1745 VM_OBJECT_WUNLOCK(obj); 1746 return (EINVAL); 1747 } 1748 1749 shmfd->shm_kmappings++; 1750 vm_object_reference_locked(obj); 1751 VM_OBJECT_WUNLOCK(obj); 1752 1753 /* Map the object into the kernel_map and wire it. */ 1754 kva = vm_map_min(kernel_map); 1755 ofs = offset & PAGE_MASK; 1756 offset = trunc_page(offset); 1757 size = round_page(size + ofs); 1758 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1759 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1760 VM_PROT_READ | VM_PROT_WRITE, 0); 1761 if (rv == KERN_SUCCESS) { 1762 rv = vm_map_wire(kernel_map, kva, kva + size, 1763 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1764 if (rv == KERN_SUCCESS) { 1765 *memp = (void *)(kva + ofs); 1766 return (0); 1767 } 1768 vm_map_remove(kernel_map, kva, kva + size); 1769 } else 1770 vm_object_deallocate(obj); 1771 1772 /* On failure, drop our mapping reference. */ 1773 VM_OBJECT_WLOCK(obj); 1774 shmfd->shm_kmappings--; 1775 VM_OBJECT_WUNLOCK(obj); 1776 1777 return (vm_mmap_to_errno(rv)); 1778 } 1779 1780 /* 1781 * We require the caller to unmap the entire entry. This allows us to 1782 * safely decrement shm_kmappings when a mapping is removed. 1783 */ 1784 int 1785 shm_unmap(struct file *fp, void *mem, size_t size) 1786 { 1787 struct shmfd *shmfd; 1788 vm_map_entry_t entry; 1789 vm_offset_t kva, ofs; 1790 vm_object_t obj; 1791 vm_pindex_t pindex; 1792 vm_prot_t prot; 1793 boolean_t wired; 1794 vm_map_t map; 1795 int rv; 1796 1797 if (fp->f_type != DTYPE_SHM) 1798 return (EINVAL); 1799 shmfd = fp->f_data; 1800 kva = (vm_offset_t)mem; 1801 ofs = kva & PAGE_MASK; 1802 kva = trunc_page(kva); 1803 size = round_page(size + ofs); 1804 map = kernel_map; 1805 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1806 &obj, &pindex, &prot, &wired); 1807 if (rv != KERN_SUCCESS) 1808 return (EINVAL); 1809 if (entry->start != kva || entry->end != kva + size) { 1810 vm_map_lookup_done(map, entry); 1811 return (EINVAL); 1812 } 1813 vm_map_lookup_done(map, entry); 1814 if (obj != shmfd->shm_object) 1815 return (EINVAL); 1816 vm_map_remove(map, kva, kva + size); 1817 VM_OBJECT_WLOCK(obj); 1818 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1819 shmfd->shm_kmappings--; 1820 VM_OBJECT_WUNLOCK(obj); 1821 return (0); 1822 } 1823 1824 static int 1825 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1826 { 1827 const char *path, *pr_path; 1828 size_t pr_pathlen; 1829 bool visible; 1830 1831 sx_assert(&shm_dict_lock, SA_LOCKED); 1832 kif->kf_type = KF_TYPE_SHM; 1833 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1834 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1835 if (shmfd->shm_path != NULL) { 1836 if (shmfd->shm_path != NULL) { 1837 path = shmfd->shm_path; 1838 pr_path = curthread->td_ucred->cr_prison->pr_path; 1839 if (strcmp(pr_path, "/") != 0) { 1840 /* Return the jail-rooted pathname. */ 1841 pr_pathlen = strlen(pr_path); 1842 visible = strncmp(path, pr_path, pr_pathlen) 1843 == 0 && path[pr_pathlen] == '/'; 1844 if (list && !visible) 1845 return (EPERM); 1846 if (visible) 1847 path += pr_pathlen; 1848 } 1849 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1850 } 1851 } 1852 return (0); 1853 } 1854 1855 static int 1856 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1857 struct filedesc *fdp __unused) 1858 { 1859 int res; 1860 1861 sx_slock(&shm_dict_lock); 1862 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1863 sx_sunlock(&shm_dict_lock); 1864 return (res); 1865 } 1866 1867 static int 1868 shm_add_seals(struct file *fp, int seals) 1869 { 1870 struct shmfd *shmfd; 1871 void *rl_cookie; 1872 vm_ooffset_t writemappings; 1873 int error, nseals; 1874 1875 error = 0; 1876 shmfd = fp->f_data; 1877 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1878 &shmfd->shm_mtx); 1879 1880 /* Even already-set seals should result in EPERM. */ 1881 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1882 error = EPERM; 1883 goto out; 1884 } 1885 nseals = seals & ~shmfd->shm_seals; 1886 if ((nseals & F_SEAL_WRITE) != 0) { 1887 if (shm_largepage(shmfd)) { 1888 error = ENOTSUP; 1889 goto out; 1890 } 1891 1892 /* 1893 * The rangelock above prevents writable mappings from being 1894 * added after we've started applying seals. The RLOCK here 1895 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1896 * writemappings will be done without a rangelock. 1897 */ 1898 VM_OBJECT_RLOCK(shmfd->shm_object); 1899 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1900 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1901 /* kmappings are also writable */ 1902 if (writemappings > 0) { 1903 error = EBUSY; 1904 goto out; 1905 } 1906 } 1907 shmfd->shm_seals |= nseals; 1908 out: 1909 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1910 return (error); 1911 } 1912 1913 static int 1914 shm_get_seals(struct file *fp, int *seals) 1915 { 1916 struct shmfd *shmfd; 1917 1918 shmfd = fp->f_data; 1919 *seals = shmfd->shm_seals; 1920 return (0); 1921 } 1922 1923 static int 1924 shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t *length, int flags) 1925 { 1926 vm_object_t object; 1927 vm_pindex_t pistart, pi, piend; 1928 vm_ooffset_t off, len; 1929 int startofs, endofs, end; 1930 int error; 1931 1932 off = *offset; 1933 len = *length; 1934 KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows")); 1935 if (off + len > shmfd->shm_size) 1936 len = shmfd->shm_size - off; 1937 object = shmfd->shm_object; 1938 startofs = off & PAGE_MASK; 1939 endofs = (off + len) & PAGE_MASK; 1940 pistart = OFF_TO_IDX(off); 1941 piend = OFF_TO_IDX(off + len); 1942 pi = OFF_TO_IDX(off + PAGE_MASK); 1943 error = 0; 1944 1945 /* Handle the case when offset is on or beyond shm size. */ 1946 if ((off_t)len <= 0) { 1947 *length = 0; 1948 return (0); 1949 } 1950 1951 VM_OBJECT_WLOCK(object); 1952 1953 if (startofs != 0) { 1954 end = pistart != piend ? PAGE_SIZE : endofs; 1955 error = shm_partial_page_invalidate(object, pistart, startofs, 1956 end); 1957 if (error) 1958 goto out; 1959 off += end - startofs; 1960 len -= end - startofs; 1961 } 1962 1963 if (pi < piend) { 1964 vm_object_page_remove(object, pi, piend, 0); 1965 off += IDX_TO_OFF(piend - pi); 1966 len -= IDX_TO_OFF(piend - pi); 1967 } 1968 1969 if (endofs != 0 && pistart != piend) { 1970 error = shm_partial_page_invalidate(object, piend, 0, endofs); 1971 if (error) 1972 goto out; 1973 off += endofs; 1974 len -= endofs; 1975 } 1976 1977 out: 1978 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1979 *offset = off; 1980 *length = len; 1981 return (error); 1982 } 1983 1984 static int 1985 shm_fspacectl(struct file *fp, int cmd, off_t *offset, off_t *length, int flags, 1986 struct ucred *active_cred, struct thread *td) 1987 { 1988 void *rl_cookie; 1989 struct shmfd *shmfd; 1990 off_t off, len; 1991 int error; 1992 1993 /* This assumes that the caller already checked for overflow. */ 1994 error = EINVAL; 1995 shmfd = fp->f_data; 1996 off = *offset; 1997 len = *length; 1998 1999 if (cmd != SPACECTL_DEALLOC || off < 0 || len <= 0 || 2000 len > OFF_MAX - off || flags != 0) 2001 return (EINVAL); 2002 2003 rl_cookie = rangelock_wlock(&shmfd->shm_rl, off, off + len, 2004 &shmfd->shm_mtx); 2005 switch (cmd) { 2006 case SPACECTL_DEALLOC: 2007 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 2008 error = EPERM; 2009 break; 2010 } 2011 error = shm_deallocate(shmfd, &off, &len, flags); 2012 *offset = off; 2013 *length = len; 2014 break; 2015 default: 2016 __assert_unreachable(); 2017 } 2018 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 2019 return (error); 2020 } 2021 2022 2023 static int 2024 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 2025 { 2026 void *rl_cookie; 2027 struct shmfd *shmfd; 2028 size_t size; 2029 int error; 2030 2031 /* This assumes that the caller already checked for overflow. */ 2032 error = 0; 2033 shmfd = fp->f_data; 2034 size = offset + len; 2035 2036 /* 2037 * Just grab the rangelock for the range that we may be attempting to 2038 * grow, rather than blocking read/write for regions we won't be 2039 * touching while this (potential) resize is in progress. Other 2040 * attempts to resize the shmfd will have to take a write lock from 0 to 2041 * OFF_MAX, so this being potentially beyond the current usable range of 2042 * the shmfd is not necessarily a concern. If other mechanisms are 2043 * added to grow a shmfd, this may need to be re-evaluated. 2044 */ 2045 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 2046 &shmfd->shm_mtx); 2047 if (size > shmfd->shm_size) 2048 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 2049 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 2050 /* Translate to posix_fallocate(2) return value as needed. */ 2051 if (error == ENOMEM) 2052 error = ENOSPC; 2053 return (error); 2054 } 2055 2056 static int 2057 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 2058 { 2059 struct shm_mapping *shmm; 2060 struct sbuf sb; 2061 struct kinfo_file kif; 2062 u_long i; 2063 int error, error2; 2064 2065 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 2066 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 2067 error = 0; 2068 sx_slock(&shm_dict_lock); 2069 for (i = 0; i < shm_hash + 1; i++) { 2070 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 2071 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 2072 &kif, true); 2073 if (error == EPERM) { 2074 error = 0; 2075 continue; 2076 } 2077 if (error != 0) 2078 break; 2079 pack_kinfo(&kif); 2080 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 2081 0 : ENOMEM; 2082 if (error != 0) 2083 break; 2084 } 2085 } 2086 sx_sunlock(&shm_dict_lock); 2087 error2 = sbuf_finish(&sb); 2088 sbuf_delete(&sb); 2089 return (error != 0 ? error : error2); 2090 } 2091 2092 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 2093 CTLFLAG_RD | CTLFLAG_PRISON | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 2094 NULL, 0, sysctl_posix_shm_list, "", 2095 "POSIX SHM list"); 2096 2097 int 2098 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 2099 struct filecaps *caps) 2100 { 2101 2102 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 2103 } 2104 2105 /* 2106 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 2107 * caller, and libc will enforce it for the traditional shm_open() call. This 2108 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 2109 * interface also includes a 'name' argument that is currently unused, but could 2110 * potentially be exported later via some interface for debugging purposes. 2111 * From the kernel's perspective, it is optional. Individual consumers like 2112 * memfd_create() may require it in order to be compatible with other systems 2113 * implementing the same function. 2114 */ 2115 int 2116 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 2117 { 2118 2119 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 2120 uap->shmflags, NULL, uap->name)); 2121 } 2122