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 int shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, 129 void *rl_cookie); 130 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 131 void *rl_cookie); 132 static int shm_copyin_path(struct thread *td, const char *userpath_in, 133 char **path_out); 134 135 static fo_rdwr_t shm_read; 136 static fo_rdwr_t shm_write; 137 static fo_truncate_t shm_truncate; 138 static fo_ioctl_t shm_ioctl; 139 static fo_stat_t shm_stat; 140 static fo_close_t shm_close; 141 static fo_chmod_t shm_chmod; 142 static fo_chown_t shm_chown; 143 static fo_seek_t shm_seek; 144 static fo_fill_kinfo_t shm_fill_kinfo; 145 static fo_mmap_t shm_mmap; 146 static fo_get_seals_t shm_get_seals; 147 static fo_add_seals_t shm_add_seals; 148 static fo_fallocate_t shm_fallocate; 149 150 /* File descriptor operations. */ 151 struct fileops shm_ops = { 152 .fo_read = shm_read, 153 .fo_write = shm_write, 154 .fo_truncate = shm_truncate, 155 .fo_ioctl = shm_ioctl, 156 .fo_poll = invfo_poll, 157 .fo_kqfilter = invfo_kqfilter, 158 .fo_stat = shm_stat, 159 .fo_close = shm_close, 160 .fo_chmod = shm_chmod, 161 .fo_chown = shm_chown, 162 .fo_sendfile = vn_sendfile, 163 .fo_seek = shm_seek, 164 .fo_fill_kinfo = shm_fill_kinfo, 165 .fo_mmap = shm_mmap, 166 .fo_get_seals = shm_get_seals, 167 .fo_add_seals = shm_add_seals, 168 .fo_fallocate = shm_fallocate, 169 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE, 170 }; 171 172 FEATURE(posix_shm, "POSIX shared memory"); 173 174 static SYSCTL_NODE(_vm, OID_AUTO, largepages, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 175 ""); 176 177 static int largepage_reclaim_tries = 1; 178 SYSCTL_INT(_vm_largepages, OID_AUTO, reclaim_tries, 179 CTLFLAG_RWTUN, &largepage_reclaim_tries, 0, 180 "Number of contig reclaims before giving up for default alloc policy"); 181 182 static int 183 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 184 { 185 vm_page_t m; 186 vm_pindex_t idx; 187 size_t tlen; 188 int error, offset, rv; 189 190 idx = OFF_TO_IDX(uio->uio_offset); 191 offset = uio->uio_offset & PAGE_MASK; 192 tlen = MIN(PAGE_SIZE - offset, len); 193 194 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 195 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 196 if (rv == VM_PAGER_OK) 197 goto found; 198 199 /* 200 * Read I/O without either a corresponding resident page or swap 201 * page: use zero_region. This is intended to avoid instantiating 202 * pages on read from a sparse region. 203 */ 204 VM_OBJECT_WLOCK(obj); 205 m = vm_page_lookup(obj, idx); 206 if (uio->uio_rw == UIO_READ && m == NULL && 207 !vm_pager_has_page(obj, idx, NULL, NULL)) { 208 VM_OBJECT_WUNLOCK(obj); 209 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 210 } 211 212 /* 213 * Although the tmpfs vnode lock is held here, it is 214 * nonetheless safe to sleep waiting for a free page. The 215 * pageout daemon does not need to acquire the tmpfs vnode 216 * lock to page out tobj's pages because tobj is a OBJT_SWAP 217 * type object. 218 */ 219 rv = vm_page_grab_valid(&m, obj, idx, 220 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 221 if (rv != VM_PAGER_OK) { 222 VM_OBJECT_WUNLOCK(obj); 223 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 224 obj, idx, rv); 225 return (EIO); 226 } 227 VM_OBJECT_WUNLOCK(obj); 228 229 found: 230 error = uiomove_fromphys(&m, offset, tlen, uio); 231 if (uio->uio_rw == UIO_WRITE && error == 0) 232 vm_page_set_dirty(m); 233 vm_page_activate(m); 234 vm_page_sunbusy(m); 235 236 return (error); 237 } 238 239 int 240 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 241 { 242 ssize_t resid; 243 size_t len; 244 int error; 245 246 error = 0; 247 while ((resid = uio->uio_resid) > 0) { 248 if (obj_size <= uio->uio_offset) 249 break; 250 len = MIN(obj_size - uio->uio_offset, resid); 251 if (len == 0) 252 break; 253 error = uiomove_object_page(obj, len, uio); 254 if (error != 0 || resid == uio->uio_resid) 255 break; 256 } 257 return (error); 258 } 259 260 static u_long count_largepages[MAXPAGESIZES]; 261 262 static int 263 shm_largepage_phys_populate(vm_object_t object, vm_pindex_t pidx, 264 int fault_type, vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last) 265 { 266 vm_page_t m; 267 int psind; 268 269 psind = object->un_pager.phys.data_val; 270 if (psind == 0 || pidx >= object->size) 271 return (VM_PAGER_FAIL); 272 *first = rounddown2(pidx, pagesizes[psind] / PAGE_SIZE); 273 274 /* 275 * We only busy the first page in the superpage run. It is 276 * useless to busy whole run since we only remove full 277 * superpage, and it takes too long to busy e.g. 512 * 512 == 278 * 262144 pages constituing 1G amd64 superage. 279 */ 280 m = vm_page_grab(object, *first, VM_ALLOC_NORMAL | VM_ALLOC_NOCREAT); 281 MPASS(m != NULL); 282 283 *last = *first + atop(pagesizes[psind]) - 1; 284 return (VM_PAGER_OK); 285 } 286 287 static boolean_t 288 shm_largepage_phys_haspage(vm_object_t object, vm_pindex_t pindex, 289 int *before, int *after) 290 { 291 int psind; 292 293 psind = object->un_pager.phys.data_val; 294 if (psind == 0 || pindex >= object->size) 295 return (FALSE); 296 if (before != NULL) { 297 *before = pindex - rounddown2(pindex, pagesizes[psind] / 298 PAGE_SIZE); 299 } 300 if (after != NULL) { 301 *after = roundup2(pindex, pagesizes[psind] / PAGE_SIZE) - 302 pindex; 303 } 304 return (TRUE); 305 } 306 307 static void 308 shm_largepage_phys_ctor(vm_object_t object, vm_prot_t prot, 309 vm_ooffset_t foff, struct ucred *cred) 310 { 311 } 312 313 static void 314 shm_largepage_phys_dtor(vm_object_t object) 315 { 316 int psind; 317 318 psind = object->un_pager.phys.data_val; 319 if (psind != 0) { 320 atomic_subtract_long(&count_largepages[psind], 321 object->size / (pagesizes[psind] / PAGE_SIZE)); 322 vm_wire_sub(object->size); 323 } else { 324 KASSERT(object->size == 0, 325 ("largepage phys obj %p not initialized bit size %#jx > 0", 326 object, (uintmax_t)object->size)); 327 } 328 } 329 330 static struct phys_pager_ops shm_largepage_phys_ops = { 331 .phys_pg_populate = shm_largepage_phys_populate, 332 .phys_pg_haspage = shm_largepage_phys_haspage, 333 .phys_pg_ctor = shm_largepage_phys_ctor, 334 .phys_pg_dtor = shm_largepage_phys_dtor, 335 }; 336 337 bool 338 shm_largepage(struct shmfd *shmfd) 339 { 340 return (shmfd->shm_object->type == OBJT_PHYS); 341 } 342 343 static int 344 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 345 { 346 struct shmfd *shmfd; 347 off_t foffset; 348 int error; 349 350 shmfd = fp->f_data; 351 foffset = foffset_lock(fp, 0); 352 error = 0; 353 switch (whence) { 354 case L_INCR: 355 if (foffset < 0 || 356 (offset > 0 && foffset > OFF_MAX - offset)) { 357 error = EOVERFLOW; 358 break; 359 } 360 offset += foffset; 361 break; 362 case L_XTND: 363 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 364 error = EOVERFLOW; 365 break; 366 } 367 offset += shmfd->shm_size; 368 break; 369 case L_SET: 370 break; 371 default: 372 error = EINVAL; 373 } 374 if (error == 0) { 375 if (offset < 0 || offset > shmfd->shm_size) 376 error = EINVAL; 377 else 378 td->td_uretoff.tdu_off = offset; 379 } 380 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 381 return (error); 382 } 383 384 static int 385 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 386 int flags, struct thread *td) 387 { 388 struct shmfd *shmfd; 389 void *rl_cookie; 390 int error; 391 392 shmfd = fp->f_data; 393 #ifdef MAC 394 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 395 if (error) 396 return (error); 397 #endif 398 foffset_lock_uio(fp, uio, flags); 399 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 400 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 401 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 402 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 403 foffset_unlock_uio(fp, uio, flags); 404 return (error); 405 } 406 407 static int 408 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 409 int flags, struct thread *td) 410 { 411 struct shmfd *shmfd; 412 void *rl_cookie; 413 int error; 414 off_t size; 415 416 shmfd = fp->f_data; 417 #ifdef MAC 418 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 419 if (error) 420 return (error); 421 #endif 422 if (shm_largepage(shmfd) && shmfd->shm_lp_psind == 0) 423 return (EINVAL); 424 foffset_lock_uio(fp, uio, flags); 425 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 426 /* 427 * Overflow is only an error if we're supposed to expand on 428 * write. Otherwise, we'll just truncate the write to the 429 * size of the file, which can only grow up to OFF_MAX. 430 */ 431 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 432 foffset_unlock_uio(fp, uio, flags); 433 return (EFBIG); 434 } 435 436 size = shmfd->shm_size; 437 } else { 438 size = uio->uio_offset + uio->uio_resid; 439 } 440 if ((flags & FOF_OFFSET) == 0) { 441 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 442 &shmfd->shm_mtx); 443 } else { 444 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 445 size, &shmfd->shm_mtx); 446 } 447 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 448 error = EPERM; 449 } else { 450 error = 0; 451 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 452 size > shmfd->shm_size) { 453 VM_OBJECT_WLOCK(shmfd->shm_object); 454 error = shm_dotruncate_locked(shmfd, size, rl_cookie); 455 VM_OBJECT_WUNLOCK(shmfd->shm_object); 456 } 457 if (error == 0) 458 error = uiomove_object(shmfd->shm_object, 459 shmfd->shm_size, uio); 460 } 461 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 462 foffset_unlock_uio(fp, uio, flags); 463 return (error); 464 } 465 466 static int 467 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 468 struct thread *td) 469 { 470 struct shmfd *shmfd; 471 #ifdef MAC 472 int error; 473 #endif 474 475 shmfd = fp->f_data; 476 #ifdef MAC 477 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 478 if (error) 479 return (error); 480 #endif 481 return (shm_dotruncate(shmfd, length)); 482 } 483 484 int 485 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 486 struct thread *td) 487 { 488 struct shmfd *shmfd; 489 struct shm_largepage_conf *conf; 490 void *rl_cookie; 491 492 shmfd = fp->f_data; 493 switch (com) { 494 case FIONBIO: 495 case FIOASYNC: 496 /* 497 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 498 * just like it would on an unlinked regular file 499 */ 500 return (0); 501 case FIOSSHMLPGCNF: 502 if (!shm_largepage(shmfd)) 503 return (ENOTTY); 504 conf = data; 505 if (shmfd->shm_lp_psind != 0 && 506 conf->psind != shmfd->shm_lp_psind) 507 return (EINVAL); 508 if (conf->psind <= 0 || conf->psind >= MAXPAGESIZES || 509 pagesizes[conf->psind] == 0) 510 return (EINVAL); 511 if (conf->alloc_policy != SHM_LARGEPAGE_ALLOC_DEFAULT && 512 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_NOWAIT && 513 conf->alloc_policy != SHM_LARGEPAGE_ALLOC_HARD) 514 return (EINVAL); 515 516 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 517 &shmfd->shm_mtx); 518 shmfd->shm_lp_psind = conf->psind; 519 shmfd->shm_lp_alloc_policy = conf->alloc_policy; 520 shmfd->shm_object->un_pager.phys.data_val = conf->psind; 521 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 522 return (0); 523 case FIOGSHMLPGCNF: 524 if (!shm_largepage(shmfd)) 525 return (ENOTTY); 526 conf = data; 527 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, OFF_MAX, 528 &shmfd->shm_mtx); 529 conf->psind = shmfd->shm_lp_psind; 530 conf->alloc_policy = shmfd->shm_lp_alloc_policy; 531 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 532 return (0); 533 default: 534 return (ENOTTY); 535 } 536 } 537 538 static int 539 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 540 struct thread *td) 541 { 542 struct shmfd *shmfd; 543 #ifdef MAC 544 int error; 545 #endif 546 547 shmfd = fp->f_data; 548 549 #ifdef MAC 550 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 551 if (error) 552 return (error); 553 #endif 554 555 /* 556 * Attempt to return sanish values for fstat() on a memory file 557 * descriptor. 558 */ 559 bzero(sb, sizeof(*sb)); 560 sb->st_blksize = PAGE_SIZE; 561 sb->st_size = shmfd->shm_size; 562 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 563 mtx_lock(&shm_timestamp_lock); 564 sb->st_atim = shmfd->shm_atime; 565 sb->st_ctim = shmfd->shm_ctime; 566 sb->st_mtim = shmfd->shm_mtime; 567 sb->st_birthtim = shmfd->shm_birthtime; 568 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 569 sb->st_uid = shmfd->shm_uid; 570 sb->st_gid = shmfd->shm_gid; 571 mtx_unlock(&shm_timestamp_lock); 572 sb->st_dev = shm_dev_ino; 573 sb->st_ino = shmfd->shm_ino; 574 sb->st_nlink = shmfd->shm_object->ref_count; 575 sb->st_blocks = shmfd->shm_object->size / 576 (pagesizes[shmfd->shm_lp_psind] >> PAGE_SHIFT); 577 578 return (0); 579 } 580 581 static int 582 shm_close(struct file *fp, struct thread *td) 583 { 584 struct shmfd *shmfd; 585 586 shmfd = fp->f_data; 587 fp->f_data = NULL; 588 shm_drop(shmfd); 589 590 return (0); 591 } 592 593 static int 594 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 595 int error; 596 char *path; 597 const char *pr_path; 598 size_t pr_pathlen; 599 600 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 601 pr_path = td->td_ucred->cr_prison->pr_path; 602 603 /* Construct a full pathname for jailed callers. */ 604 pr_pathlen = strcmp(pr_path, "/") == 605 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 606 error = copyinstr(userpath_in, path + pr_pathlen, 607 MAXPATHLEN - pr_pathlen, NULL); 608 if (error != 0) 609 goto out; 610 611 #ifdef KTRACE 612 if (KTRPOINT(curthread, KTR_NAMEI)) 613 ktrnamei(path); 614 #endif 615 616 /* Require paths to start with a '/' character. */ 617 if (path[pr_pathlen] != '/') { 618 error = EINVAL; 619 goto out; 620 } 621 622 *path_out = path; 623 624 out: 625 if (error != 0) 626 free(path, M_SHMFD); 627 628 return (error); 629 } 630 631 static int 632 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 633 { 634 vm_object_t object; 635 vm_page_t m; 636 vm_pindex_t idx, nobjsize; 637 vm_ooffset_t delta; 638 int base, rv; 639 640 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 641 object = shmfd->shm_object; 642 VM_OBJECT_ASSERT_WLOCKED(object); 643 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 644 if (length == shmfd->shm_size) 645 return (0); 646 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 647 648 /* Are we shrinking? If so, trim the end. */ 649 if (length < shmfd->shm_size) { 650 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 651 return (EPERM); 652 653 /* 654 * Disallow any requests to shrink the size if this 655 * object is mapped into the kernel. 656 */ 657 if (shmfd->shm_kmappings > 0) 658 return (EBUSY); 659 660 /* 661 * Zero the truncated part of the last page. 662 */ 663 base = length & PAGE_MASK; 664 if (base != 0) { 665 idx = OFF_TO_IDX(length); 666 retry: 667 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 668 if (m != NULL) { 669 MPASS(vm_page_all_valid(m)); 670 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 671 m = vm_page_alloc(object, idx, 672 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 673 if (m == NULL) 674 goto retry; 675 vm_object_pip_add(object, 1); 676 VM_OBJECT_WUNLOCK(object); 677 rv = vm_pager_get_pages(object, &m, 1, NULL, 678 NULL); 679 VM_OBJECT_WLOCK(object); 680 vm_object_pip_wakeup(object); 681 if (rv == VM_PAGER_OK) { 682 /* 683 * Since the page was not resident, 684 * and therefore not recently 685 * accessed, immediately enqueue it 686 * for asynchronous laundering. The 687 * current operation is not regarded 688 * as an access. 689 */ 690 vm_page_launder(m); 691 } else { 692 vm_page_free(m); 693 VM_OBJECT_WUNLOCK(object); 694 return (EIO); 695 } 696 } 697 if (m != NULL) { 698 pmap_zero_page_area(m, base, PAGE_SIZE - base); 699 KASSERT(vm_page_all_valid(m), 700 ("shm_dotruncate: page %p is invalid", m)); 701 vm_page_set_dirty(m); 702 vm_page_xunbusy(m); 703 } 704 } 705 delta = IDX_TO_OFF(object->size - nobjsize); 706 707 if (nobjsize < object->size) 708 vm_object_page_remove(object, nobjsize, object->size, 709 0); 710 711 /* Free the swap accounted for shm */ 712 swap_release_by_cred(delta, object->cred); 713 object->charge -= delta; 714 } else { 715 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 716 return (EPERM); 717 718 /* Try to reserve additional swap space. */ 719 delta = IDX_TO_OFF(nobjsize - object->size); 720 if (!swap_reserve_by_cred(delta, object->cred)) 721 return (ENOMEM); 722 object->charge += delta; 723 } 724 shmfd->shm_size = length; 725 mtx_lock(&shm_timestamp_lock); 726 vfs_timestamp(&shmfd->shm_ctime); 727 shmfd->shm_mtime = shmfd->shm_ctime; 728 mtx_unlock(&shm_timestamp_lock); 729 object->size = nobjsize; 730 return (0); 731 } 732 733 static int 734 shm_dotruncate_largepage(struct shmfd *shmfd, off_t length, void *rl_cookie) 735 { 736 vm_object_t object; 737 vm_page_t m; 738 vm_pindex_t newobjsz, oldobjsz; 739 int aflags, error, i, psind, try; 740 741 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 742 object = shmfd->shm_object; 743 VM_OBJECT_ASSERT_WLOCKED(object); 744 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 745 746 oldobjsz = object->size; 747 newobjsz = OFF_TO_IDX(length); 748 if (length == shmfd->shm_size) 749 return (0); 750 psind = shmfd->shm_lp_psind; 751 if (psind == 0 && length != 0) 752 return (EINVAL); 753 if ((length & (pagesizes[psind] - 1)) != 0) 754 return (EINVAL); 755 756 if (length < shmfd->shm_size) { 757 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 758 return (EPERM); 759 if (shmfd->shm_kmappings > 0) 760 return (EBUSY); 761 return (ENOTSUP); /* Pages are unmanaged. */ 762 #if 0 763 vm_object_page_remove(object, newobjsz, oldobjsz, 0); 764 object->size = newobjsz; 765 shmfd->shm_size = length; 766 return (0); 767 #endif 768 } 769 770 aflags = VM_ALLOC_NORMAL | VM_ALLOC_ZERO; 771 if (shmfd->shm_lp_alloc_policy == SHM_LARGEPAGE_ALLOC_NOWAIT) 772 aflags |= VM_ALLOC_WAITFAIL; 773 try = 0; 774 775 /* 776 * Extend shmfd and object, keeping all already fully 777 * allocated large pages intact even on error, because dropped 778 * object lock might allowed mapping of them. 779 */ 780 while (object->size < newobjsz) { 781 m = vm_page_alloc_contig(object, object->size, aflags, 782 pagesizes[psind] / PAGE_SIZE, 0, ~0, 783 pagesizes[psind], 0, 784 VM_MEMATTR_DEFAULT); 785 if (m == NULL) { 786 VM_OBJECT_WUNLOCK(object); 787 if (shmfd->shm_lp_alloc_policy == 788 SHM_LARGEPAGE_ALLOC_NOWAIT || 789 (shmfd->shm_lp_alloc_policy == 790 SHM_LARGEPAGE_ALLOC_DEFAULT && 791 try >= largepage_reclaim_tries)) { 792 VM_OBJECT_WLOCK(object); 793 return (ENOMEM); 794 } 795 error = vm_page_reclaim_contig(aflags, 796 pagesizes[psind] / PAGE_SIZE, 0, ~0, 797 pagesizes[psind], 0) ? 0 : 798 vm_wait_intr(object); 799 if (error != 0) { 800 VM_OBJECT_WLOCK(object); 801 return (error); 802 } 803 try++; 804 VM_OBJECT_WLOCK(object); 805 continue; 806 } 807 try = 0; 808 for (i = 0; i < pagesizes[psind] / PAGE_SIZE; i++) { 809 if ((m[i].flags & PG_ZERO) == 0) 810 pmap_zero_page(&m[i]); 811 vm_page_valid(&m[i]); 812 vm_page_xunbusy(&m[i]); 813 } 814 object->size += OFF_TO_IDX(pagesizes[psind]); 815 shmfd->shm_size += pagesizes[psind]; 816 atomic_add_long(&count_largepages[psind], 1); 817 vm_wire_add(atop(pagesizes[psind])); 818 } 819 return (0); 820 } 821 822 static int 823 shm_dotruncate_cookie(struct shmfd *shmfd, off_t length, void *rl_cookie) 824 { 825 int error; 826 827 VM_OBJECT_WLOCK(shmfd->shm_object); 828 error = shm_largepage(shmfd) ? shm_dotruncate_largepage(shmfd, 829 length, rl_cookie) : shm_dotruncate_locked(shmfd, length, 830 rl_cookie); 831 VM_OBJECT_WUNLOCK(shmfd->shm_object); 832 return (error); 833 } 834 835 int 836 shm_dotruncate(struct shmfd *shmfd, off_t length) 837 { 838 void *rl_cookie; 839 int error; 840 841 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 842 &shmfd->shm_mtx); 843 error = shm_dotruncate_cookie(shmfd, length, rl_cookie); 844 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 845 return (error); 846 } 847 848 /* 849 * shmfd object management including creation and reference counting 850 * routines. 851 */ 852 struct shmfd * 853 shm_alloc(struct ucred *ucred, mode_t mode, bool largepage) 854 { 855 struct shmfd *shmfd; 856 857 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 858 shmfd->shm_size = 0; 859 shmfd->shm_uid = ucred->cr_uid; 860 shmfd->shm_gid = ucred->cr_gid; 861 shmfd->shm_mode = mode; 862 if (largepage) { 863 shmfd->shm_object = phys_pager_allocate(NULL, 864 &shm_largepage_phys_ops, NULL, shmfd->shm_size, 865 VM_PROT_DEFAULT, 0, ucred); 866 shmfd->shm_lp_alloc_policy = SHM_LARGEPAGE_ALLOC_DEFAULT; 867 } else { 868 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 869 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 870 } 871 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 872 vfs_timestamp(&shmfd->shm_birthtime); 873 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 874 shmfd->shm_birthtime; 875 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 876 refcount_init(&shmfd->shm_refs, 1); 877 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 878 rangelock_init(&shmfd->shm_rl); 879 #ifdef MAC 880 mac_posixshm_init(shmfd); 881 mac_posixshm_create(ucred, shmfd); 882 #endif 883 884 return (shmfd); 885 } 886 887 struct shmfd * 888 shm_hold(struct shmfd *shmfd) 889 { 890 891 refcount_acquire(&shmfd->shm_refs); 892 return (shmfd); 893 } 894 895 void 896 shm_drop(struct shmfd *shmfd) 897 { 898 899 if (refcount_release(&shmfd->shm_refs)) { 900 #ifdef MAC 901 mac_posixshm_destroy(shmfd); 902 #endif 903 rangelock_destroy(&shmfd->shm_rl); 904 mtx_destroy(&shmfd->shm_mtx); 905 vm_object_deallocate(shmfd->shm_object); 906 free(shmfd, M_SHMFD); 907 } 908 } 909 910 /* 911 * Determine if the credentials have sufficient permissions for a 912 * specified combination of FREAD and FWRITE. 913 */ 914 int 915 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 916 { 917 accmode_t accmode; 918 int error; 919 920 accmode = 0; 921 if (flags & FREAD) 922 accmode |= VREAD; 923 if (flags & FWRITE) 924 accmode |= VWRITE; 925 mtx_lock(&shm_timestamp_lock); 926 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 927 accmode, ucred); 928 mtx_unlock(&shm_timestamp_lock); 929 return (error); 930 } 931 932 static void 933 shm_init(void *arg) 934 { 935 char name[32]; 936 int i; 937 938 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 939 sx_init(&shm_dict_lock, "shm dictionary"); 940 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 941 new_unrhdr64(&shm_ino_unr, 1); 942 shm_dev_ino = devfs_alloc_cdp_inode(); 943 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 944 945 for (i = 1; i < MAXPAGESIZES; i++) { 946 if (pagesizes[i] == 0) 947 break; 948 #define M (1024 * 1024) 949 #define G (1024 * M) 950 if (pagesizes[i] >= G) 951 snprintf(name, sizeof(name), "%luG", pagesizes[i] / G); 952 else if (pagesizes[i] >= M) 953 snprintf(name, sizeof(name), "%luM", pagesizes[i] / M); 954 else 955 snprintf(name, sizeof(name), "%lu", pagesizes[i]); 956 #undef G 957 #undef M 958 SYSCTL_ADD_ULONG(NULL, SYSCTL_STATIC_CHILDREN(_vm_largepages), 959 OID_AUTO, name, CTLFLAG_RD, &count_largepages[i], 960 "number of non-transient largepages allocated"); 961 } 962 } 963 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 964 965 /* 966 * Dictionary management. We maintain an in-kernel dictionary to map 967 * paths to shmfd objects. We use the FNV hash on the path to store 968 * the mappings in a hash table. 969 */ 970 static struct shmfd * 971 shm_lookup(char *path, Fnv32_t fnv) 972 { 973 struct shm_mapping *map; 974 975 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 976 if (map->sm_fnv != fnv) 977 continue; 978 if (strcmp(map->sm_path, path) == 0) 979 return (map->sm_shmfd); 980 } 981 982 return (NULL); 983 } 984 985 static void 986 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 987 { 988 struct shm_mapping *map; 989 990 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 991 map->sm_path = path; 992 map->sm_fnv = fnv; 993 map->sm_shmfd = shm_hold(shmfd); 994 shmfd->shm_path = path; 995 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 996 } 997 998 static int 999 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 1000 { 1001 struct shm_mapping *map; 1002 int error; 1003 1004 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 1005 if (map->sm_fnv != fnv) 1006 continue; 1007 if (strcmp(map->sm_path, path) == 0) { 1008 #ifdef MAC 1009 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 1010 if (error) 1011 return (error); 1012 #endif 1013 error = shm_access(map->sm_shmfd, ucred, 1014 FREAD | FWRITE); 1015 if (error) 1016 return (error); 1017 map->sm_shmfd->shm_path = NULL; 1018 LIST_REMOVE(map, sm_link); 1019 shm_drop(map->sm_shmfd); 1020 free(map->sm_path, M_SHMFD); 1021 free(map, M_SHMFD); 1022 return (0); 1023 } 1024 } 1025 1026 return (ENOENT); 1027 } 1028 1029 int 1030 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 1031 int shmflags, struct filecaps *fcaps, const char *name __unused) 1032 { 1033 struct filedesc *fdp; 1034 struct shmfd *shmfd; 1035 struct file *fp; 1036 char *path; 1037 void *rl_cookie; 1038 Fnv32_t fnv; 1039 mode_t cmode; 1040 int error, fd, initial_seals; 1041 bool largepage; 1042 1043 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE | 1044 SHM_LARGEPAGE)) != 0) 1045 return (EINVAL); 1046 1047 initial_seals = F_SEAL_SEAL; 1048 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1049 initial_seals &= ~F_SEAL_SEAL; 1050 1051 #ifdef CAPABILITY_MODE 1052 /* 1053 * shm_open(2) is only allowed for anonymous objects. 1054 */ 1055 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 1056 return (ECAPMODE); 1057 #endif 1058 1059 AUDIT_ARG_FFLAGS(flags); 1060 AUDIT_ARG_MODE(mode); 1061 1062 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 1063 return (EINVAL); 1064 1065 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 1066 return (EINVAL); 1067 1068 largepage = (shmflags & SHM_LARGEPAGE) != 0; 1069 #if !defined(__amd64__) 1070 if (largepage) 1071 return (ENOTTY); 1072 #endif 1073 1074 /* 1075 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 1076 * If the decision is made later to allow additional seals, care must be 1077 * taken below to ensure that the seals are properly set if the shmfd 1078 * already existed -- this currently assumes that only F_SEAL_SEAL can 1079 * be set and doesn't take further precautions to ensure the validity of 1080 * the seals being added with respect to current mappings. 1081 */ 1082 if ((initial_seals & ~F_SEAL_SEAL) != 0) 1083 return (EINVAL); 1084 1085 fdp = td->td_proc->p_fd; 1086 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 1087 1088 /* 1089 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 1090 * by POSIX. We allow it to be unset here so that an in-kernel 1091 * interface may be written as a thin layer around shm, optionally not 1092 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 1093 * in sys_shm_open() to keep this implementation compliant. 1094 */ 1095 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 1096 if (error) 1097 return (error); 1098 1099 /* A SHM_ANON path pointer creates an anonymous object. */ 1100 if (userpath == SHM_ANON) { 1101 /* A read-only anonymous object is pointless. */ 1102 if ((flags & O_ACCMODE) == O_RDONLY) { 1103 fdclose(td, fp, fd); 1104 fdrop(fp, td); 1105 return (EINVAL); 1106 } 1107 shmfd = shm_alloc(td->td_ucred, cmode, largepage); 1108 shmfd->shm_seals = initial_seals; 1109 shmfd->shm_flags = shmflags; 1110 } else { 1111 error = shm_copyin_path(td, userpath, &path); 1112 if (error != 0) { 1113 fdclose(td, fp, fd); 1114 fdrop(fp, td); 1115 return (error); 1116 } 1117 1118 AUDIT_ARG_UPATH1_CANON(path); 1119 fnv = fnv_32_str(path, FNV1_32_INIT); 1120 sx_xlock(&shm_dict_lock); 1121 shmfd = shm_lookup(path, fnv); 1122 if (shmfd == NULL) { 1123 /* Object does not yet exist, create it if requested. */ 1124 if (flags & O_CREAT) { 1125 #ifdef MAC 1126 error = mac_posixshm_check_create(td->td_ucred, 1127 path); 1128 if (error == 0) { 1129 #endif 1130 shmfd = shm_alloc(td->td_ucred, cmode, 1131 largepage); 1132 shmfd->shm_seals = initial_seals; 1133 shmfd->shm_flags = shmflags; 1134 shm_insert(path, fnv, shmfd); 1135 #ifdef MAC 1136 } 1137 #endif 1138 } else { 1139 free(path, M_SHMFD); 1140 error = ENOENT; 1141 } 1142 } else { 1143 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1144 &shmfd->shm_mtx); 1145 1146 /* 1147 * kern_shm_open() likely shouldn't ever error out on 1148 * trying to set a seal that already exists, unlike 1149 * F_ADD_SEALS. This would break terribly as 1150 * shm_open(2) actually sets F_SEAL_SEAL to maintain 1151 * historical behavior where the underlying file could 1152 * not be sealed. 1153 */ 1154 initial_seals &= ~shmfd->shm_seals; 1155 1156 /* 1157 * Object already exists, obtain a new 1158 * reference if requested and permitted. 1159 */ 1160 free(path, M_SHMFD); 1161 1162 /* 1163 * initial_seals can't set additional seals if we've 1164 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 1165 * then we've already removed that one from 1166 * initial_seals. This is currently redundant as we 1167 * only allow setting F_SEAL_SEAL at creation time, but 1168 * it's cheap to check and decreases the effort required 1169 * to allow additional seals. 1170 */ 1171 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 1172 initial_seals != 0) 1173 error = EPERM; 1174 else if ((flags & (O_CREAT | O_EXCL)) == 1175 (O_CREAT | O_EXCL)) 1176 error = EEXIST; 1177 else if (shmflags != 0 && shmflags != shmfd->shm_flags) 1178 error = EINVAL; 1179 else { 1180 #ifdef MAC 1181 error = mac_posixshm_check_open(td->td_ucred, 1182 shmfd, FFLAGS(flags & O_ACCMODE)); 1183 if (error == 0) 1184 #endif 1185 error = shm_access(shmfd, td->td_ucred, 1186 FFLAGS(flags & O_ACCMODE)); 1187 } 1188 1189 /* 1190 * Truncate the file back to zero length if 1191 * O_TRUNC was specified and the object was 1192 * opened with read/write. 1193 */ 1194 if (error == 0 && 1195 (flags & (O_ACCMODE | O_TRUNC)) == 1196 (O_RDWR | O_TRUNC)) { 1197 VM_OBJECT_WLOCK(shmfd->shm_object); 1198 #ifdef MAC 1199 error = mac_posixshm_check_truncate( 1200 td->td_ucred, fp->f_cred, shmfd); 1201 if (error == 0) 1202 #endif 1203 error = shm_dotruncate_locked(shmfd, 0, 1204 rl_cookie); 1205 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1206 } 1207 if (error == 0) { 1208 /* 1209 * Currently we only allow F_SEAL_SEAL to be 1210 * set initially. As noted above, this would 1211 * need to be reworked should that change. 1212 */ 1213 shmfd->shm_seals |= initial_seals; 1214 shm_hold(shmfd); 1215 } 1216 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 1217 &shmfd->shm_mtx); 1218 } 1219 sx_xunlock(&shm_dict_lock); 1220 1221 if (error) { 1222 fdclose(td, fp, fd); 1223 fdrop(fp, td); 1224 return (error); 1225 } 1226 } 1227 1228 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 1229 1230 td->td_retval[0] = fd; 1231 fdrop(fp, td); 1232 1233 return (0); 1234 } 1235 1236 /* System calls. */ 1237 #ifdef COMPAT_FREEBSD12 1238 int 1239 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 1240 { 1241 1242 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 1243 uap->mode, NULL)); 1244 } 1245 #endif 1246 1247 int 1248 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 1249 { 1250 char *path; 1251 Fnv32_t fnv; 1252 int error; 1253 1254 error = shm_copyin_path(td, uap->path, &path); 1255 if (error != 0) 1256 return (error); 1257 1258 AUDIT_ARG_UPATH1_CANON(path); 1259 fnv = fnv_32_str(path, FNV1_32_INIT); 1260 sx_xlock(&shm_dict_lock); 1261 error = shm_remove(path, fnv, td->td_ucred); 1262 sx_xunlock(&shm_dict_lock); 1263 free(path, M_SHMFD); 1264 1265 return (error); 1266 } 1267 1268 int 1269 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 1270 { 1271 char *path_from = NULL, *path_to = NULL; 1272 Fnv32_t fnv_from, fnv_to; 1273 struct shmfd *fd_from; 1274 struct shmfd *fd_to; 1275 int error; 1276 int flags; 1277 1278 flags = uap->flags; 1279 AUDIT_ARG_FFLAGS(flags); 1280 1281 /* 1282 * Make sure the user passed only valid flags. 1283 * If you add a new flag, please add a new term here. 1284 */ 1285 if ((flags & ~( 1286 SHM_RENAME_NOREPLACE | 1287 SHM_RENAME_EXCHANGE 1288 )) != 0) { 1289 error = EINVAL; 1290 goto out; 1291 } 1292 1293 /* 1294 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1295 * force the user to choose one or the other. 1296 */ 1297 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1298 (flags & SHM_RENAME_EXCHANGE) != 0) { 1299 error = EINVAL; 1300 goto out; 1301 } 1302 1303 /* Renaming to or from anonymous makes no sense */ 1304 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1305 error = EINVAL; 1306 goto out; 1307 } 1308 1309 error = shm_copyin_path(td, uap->path_from, &path_from); 1310 if (error != 0) 1311 goto out; 1312 1313 error = shm_copyin_path(td, uap->path_to, &path_to); 1314 if (error != 0) 1315 goto out; 1316 1317 AUDIT_ARG_UPATH1_CANON(path_from); 1318 AUDIT_ARG_UPATH2_CANON(path_to); 1319 1320 /* Rename with from/to equal is a no-op */ 1321 if (strcmp(path_from, path_to) == 0) 1322 goto out; 1323 1324 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1325 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1326 1327 sx_xlock(&shm_dict_lock); 1328 1329 fd_from = shm_lookup(path_from, fnv_from); 1330 if (fd_from == NULL) { 1331 error = ENOENT; 1332 goto out_locked; 1333 } 1334 1335 fd_to = shm_lookup(path_to, fnv_to); 1336 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1337 error = EEXIST; 1338 goto out_locked; 1339 } 1340 1341 /* 1342 * Unconditionally prevents shm_remove from invalidating the 'from' 1343 * shm's state. 1344 */ 1345 shm_hold(fd_from); 1346 error = shm_remove(path_from, fnv_from, td->td_ucred); 1347 1348 /* 1349 * One of my assumptions failed if ENOENT (e.g. locking didn't 1350 * protect us) 1351 */ 1352 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1353 path_from)); 1354 if (error != 0) { 1355 shm_drop(fd_from); 1356 goto out_locked; 1357 } 1358 1359 /* 1360 * If we are exchanging, we need to ensure the shm_remove below 1361 * doesn't invalidate the dest shm's state. 1362 */ 1363 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1364 shm_hold(fd_to); 1365 1366 /* 1367 * NOTE: if path_to is not already in the hash, c'est la vie; 1368 * it simply means we have nothing already at path_to to unlink. 1369 * That is the ENOENT case. 1370 * 1371 * If we somehow don't have access to unlink this guy, but 1372 * did for the shm at path_from, then relink the shm to path_from 1373 * and abort with EACCES. 1374 * 1375 * All other errors: that is weird; let's relink and abort the 1376 * operation. 1377 */ 1378 error = shm_remove(path_to, fnv_to, td->td_ucred); 1379 if (error != 0 && error != ENOENT) { 1380 shm_insert(path_from, fnv_from, fd_from); 1381 shm_drop(fd_from); 1382 /* Don't free path_from now, since the hash references it */ 1383 path_from = NULL; 1384 goto out_locked; 1385 } 1386 1387 error = 0; 1388 1389 shm_insert(path_to, fnv_to, fd_from); 1390 1391 /* Don't free path_to now, since the hash references it */ 1392 path_to = NULL; 1393 1394 /* We kept a ref when we removed, and incremented again in insert */ 1395 shm_drop(fd_from); 1396 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1397 fd_from->shm_refs)); 1398 1399 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1400 shm_insert(path_from, fnv_from, fd_to); 1401 path_from = NULL; 1402 shm_drop(fd_to); 1403 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1404 fd_to->shm_refs)); 1405 } 1406 1407 out_locked: 1408 sx_xunlock(&shm_dict_lock); 1409 1410 out: 1411 free(path_from, M_SHMFD); 1412 free(path_to, M_SHMFD); 1413 return (error); 1414 } 1415 1416 static int 1417 shm_mmap_large(struct shmfd *shmfd, vm_map_t map, vm_offset_t *addr, 1418 vm_size_t size, vm_prot_t prot, vm_prot_t max_prot, int flags, 1419 vm_ooffset_t foff, bool writecounted, struct thread *td) 1420 { 1421 struct vmspace *vms; 1422 vm_map_entry_t next_entry, prev_entry; 1423 vm_offset_t align, mask, maxaddr; 1424 int docow, error, rv, try; 1425 bool curmap; 1426 1427 if (shmfd->shm_lp_psind == 0) 1428 return (EINVAL); 1429 1430 /* MAP_PRIVATE is disabled */ 1431 if ((flags & ~(MAP_SHARED | MAP_FIXED | MAP_EXCL | 1432 MAP_NOCORE | 1433 #ifdef MAP_32BIT 1434 MAP_32BIT | 1435 #endif 1436 MAP_ALIGNMENT_MASK)) != 0) 1437 return (EINVAL); 1438 1439 vms = td->td_proc->p_vmspace; 1440 curmap = map == &vms->vm_map; 1441 if (curmap) { 1442 error = kern_mmap_racct_check(td, map, size); 1443 if (error != 0) 1444 return (error); 1445 } 1446 1447 docow = shmfd->shm_lp_psind << MAP_SPLIT_BOUNDARY_SHIFT; 1448 docow |= MAP_INHERIT_SHARE; 1449 if ((flags & MAP_NOCORE) != 0) 1450 docow |= MAP_DISABLE_COREDUMP; 1451 if (writecounted) 1452 docow |= MAP_WRITECOUNT; 1453 1454 mask = pagesizes[shmfd->shm_lp_psind] - 1; 1455 if ((foff & mask) != 0) 1456 return (EINVAL); 1457 maxaddr = vm_map_max(map); 1458 #ifdef MAP_32BIT 1459 if ((flags & MAP_32BIT) != 0 && maxaddr > MAP_32BIT_MAX_ADDR) 1460 maxaddr = MAP_32BIT_MAX_ADDR; 1461 #endif 1462 if (size == 0 || (size & mask) != 0 || 1463 (*addr != 0 && ((*addr & mask) != 0 || 1464 *addr + size < *addr || *addr + size > maxaddr))) 1465 return (EINVAL); 1466 1467 align = flags & MAP_ALIGNMENT_MASK; 1468 if (align == 0) { 1469 align = pagesizes[shmfd->shm_lp_psind]; 1470 } else if (align == MAP_ALIGNED_SUPER) { 1471 if (shmfd->shm_lp_psind != 1) 1472 return (EINVAL); 1473 align = pagesizes[1]; 1474 } else { 1475 align >>= MAP_ALIGNMENT_SHIFT; 1476 align = 1ULL << align; 1477 /* Also handles overflow. */ 1478 if (align < pagesizes[shmfd->shm_lp_psind]) 1479 return (EINVAL); 1480 } 1481 1482 vm_map_lock(map); 1483 if ((flags & MAP_FIXED) == 0) { 1484 try = 1; 1485 if (curmap && (*addr == 0 || 1486 (*addr >= round_page((vm_offset_t)vms->vm_taddr) && 1487 *addr < round_page((vm_offset_t)vms->vm_daddr + 1488 lim_max(td, RLIMIT_DATA))))) { 1489 *addr = roundup2((vm_offset_t)vms->vm_daddr + 1490 lim_max(td, RLIMIT_DATA), 1491 pagesizes[shmfd->shm_lp_psind]); 1492 } 1493 again: 1494 rv = vm_map_find_aligned(map, addr, size, maxaddr, align); 1495 if (rv != KERN_SUCCESS) { 1496 if (try == 1) { 1497 try = 2; 1498 *addr = vm_map_min(map); 1499 if ((*addr & mask) != 0) 1500 *addr = (*addr + mask) & mask; 1501 goto again; 1502 } 1503 goto fail1; 1504 } 1505 } else if ((flags & MAP_EXCL) == 0) { 1506 rv = vm_map_delete(map, *addr, *addr + size); 1507 if (rv != KERN_SUCCESS) 1508 goto fail1; 1509 } else { 1510 error = ENOSPC; 1511 if (vm_map_lookup_entry(map, *addr, &prev_entry)) 1512 goto fail; 1513 next_entry = vm_map_entry_succ(prev_entry); 1514 if (next_entry->start < *addr + size) 1515 goto fail; 1516 } 1517 1518 rv = vm_map_insert(map, shmfd->shm_object, foff, *addr, *addr + size, 1519 prot, max_prot, docow); 1520 fail1: 1521 error = vm_mmap_to_errno(rv); 1522 fail: 1523 vm_map_unlock(map); 1524 return (error); 1525 } 1526 1527 static int 1528 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1529 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1530 vm_ooffset_t foff, struct thread *td) 1531 { 1532 struct shmfd *shmfd; 1533 vm_prot_t maxprot; 1534 int error; 1535 bool writecnt; 1536 void *rl_cookie; 1537 1538 shmfd = fp->f_data; 1539 maxprot = VM_PROT_NONE; 1540 1541 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1542 &shmfd->shm_mtx); 1543 /* FREAD should always be set. */ 1544 if ((fp->f_flag & FREAD) != 0) 1545 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1546 1547 /* 1548 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1549 * mapping with a write seal applied. Private mappings are always 1550 * writeable. 1551 */ 1552 if ((flags & MAP_SHARED) == 0) { 1553 cap_maxprot |= VM_PROT_WRITE; 1554 maxprot |= VM_PROT_WRITE; 1555 writecnt = false; 1556 } else { 1557 if ((fp->f_flag & FWRITE) != 0 && 1558 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1559 maxprot |= VM_PROT_WRITE; 1560 1561 /* 1562 * Any mappings from a writable descriptor may be upgraded to 1563 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1564 * applied between the open and subsequent mmap(2). We want to 1565 * reject application of a write seal as long as any such 1566 * mapping exists so that the seal cannot be trivially bypassed. 1567 */ 1568 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1569 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1570 error = EACCES; 1571 goto out; 1572 } 1573 } 1574 maxprot &= cap_maxprot; 1575 1576 /* See comment in vn_mmap(). */ 1577 if ( 1578 #ifdef _LP64 1579 objsize > OFF_MAX || 1580 #endif 1581 foff < 0 || foff > OFF_MAX - objsize) { 1582 error = EINVAL; 1583 goto out; 1584 } 1585 1586 #ifdef MAC 1587 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1588 if (error != 0) 1589 goto out; 1590 #endif 1591 1592 mtx_lock(&shm_timestamp_lock); 1593 vfs_timestamp(&shmfd->shm_atime); 1594 mtx_unlock(&shm_timestamp_lock); 1595 vm_object_reference(shmfd->shm_object); 1596 1597 if (writecnt) 1598 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 1599 if (shm_largepage(shmfd)) { 1600 error = shm_mmap_large(shmfd, map, addr, objsize, prot, 1601 maxprot, flags, foff, writecnt, td); 1602 } else { 1603 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1604 shmfd->shm_object, foff, writecnt, td); 1605 } 1606 if (error != 0) { 1607 if (writecnt) 1608 vm_pager_release_writecount(shmfd->shm_object, 0, 1609 objsize); 1610 vm_object_deallocate(shmfd->shm_object); 1611 } 1612 out: 1613 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1614 return (error); 1615 } 1616 1617 static int 1618 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1619 struct thread *td) 1620 { 1621 struct shmfd *shmfd; 1622 int error; 1623 1624 error = 0; 1625 shmfd = fp->f_data; 1626 mtx_lock(&shm_timestamp_lock); 1627 /* 1628 * SUSv4 says that x bits of permission need not be affected. 1629 * Be consistent with our shm_open there. 1630 */ 1631 #ifdef MAC 1632 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1633 if (error != 0) 1634 goto out; 1635 #endif 1636 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 1637 VADMIN, active_cred); 1638 if (error != 0) 1639 goto out; 1640 shmfd->shm_mode = mode & ACCESSPERMS; 1641 out: 1642 mtx_unlock(&shm_timestamp_lock); 1643 return (error); 1644 } 1645 1646 static int 1647 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1648 struct thread *td) 1649 { 1650 struct shmfd *shmfd; 1651 int error; 1652 1653 error = 0; 1654 shmfd = fp->f_data; 1655 mtx_lock(&shm_timestamp_lock); 1656 #ifdef MAC 1657 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1658 if (error != 0) 1659 goto out; 1660 #endif 1661 if (uid == (uid_t)-1) 1662 uid = shmfd->shm_uid; 1663 if (gid == (gid_t)-1) 1664 gid = shmfd->shm_gid; 1665 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1666 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1667 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1668 goto out; 1669 shmfd->shm_uid = uid; 1670 shmfd->shm_gid = gid; 1671 out: 1672 mtx_unlock(&shm_timestamp_lock); 1673 return (error); 1674 } 1675 1676 /* 1677 * Helper routines to allow the backing object of a shared memory file 1678 * descriptor to be mapped in the kernel. 1679 */ 1680 int 1681 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1682 { 1683 struct shmfd *shmfd; 1684 vm_offset_t kva, ofs; 1685 vm_object_t obj; 1686 int rv; 1687 1688 if (fp->f_type != DTYPE_SHM) 1689 return (EINVAL); 1690 shmfd = fp->f_data; 1691 obj = shmfd->shm_object; 1692 VM_OBJECT_WLOCK(obj); 1693 /* 1694 * XXXRW: This validation is probably insufficient, and subject to 1695 * sign errors. It should be fixed. 1696 */ 1697 if (offset >= shmfd->shm_size || 1698 offset + size > round_page(shmfd->shm_size)) { 1699 VM_OBJECT_WUNLOCK(obj); 1700 return (EINVAL); 1701 } 1702 1703 shmfd->shm_kmappings++; 1704 vm_object_reference_locked(obj); 1705 VM_OBJECT_WUNLOCK(obj); 1706 1707 /* Map the object into the kernel_map and wire it. */ 1708 kva = vm_map_min(kernel_map); 1709 ofs = offset & PAGE_MASK; 1710 offset = trunc_page(offset); 1711 size = round_page(size + ofs); 1712 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1713 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1714 VM_PROT_READ | VM_PROT_WRITE, 0); 1715 if (rv == KERN_SUCCESS) { 1716 rv = vm_map_wire(kernel_map, kva, kva + size, 1717 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1718 if (rv == KERN_SUCCESS) { 1719 *memp = (void *)(kva + ofs); 1720 return (0); 1721 } 1722 vm_map_remove(kernel_map, kva, kva + size); 1723 } else 1724 vm_object_deallocate(obj); 1725 1726 /* On failure, drop our mapping reference. */ 1727 VM_OBJECT_WLOCK(obj); 1728 shmfd->shm_kmappings--; 1729 VM_OBJECT_WUNLOCK(obj); 1730 1731 return (vm_mmap_to_errno(rv)); 1732 } 1733 1734 /* 1735 * We require the caller to unmap the entire entry. This allows us to 1736 * safely decrement shm_kmappings when a mapping is removed. 1737 */ 1738 int 1739 shm_unmap(struct file *fp, void *mem, size_t size) 1740 { 1741 struct shmfd *shmfd; 1742 vm_map_entry_t entry; 1743 vm_offset_t kva, ofs; 1744 vm_object_t obj; 1745 vm_pindex_t pindex; 1746 vm_prot_t prot; 1747 boolean_t wired; 1748 vm_map_t map; 1749 int rv; 1750 1751 if (fp->f_type != DTYPE_SHM) 1752 return (EINVAL); 1753 shmfd = fp->f_data; 1754 kva = (vm_offset_t)mem; 1755 ofs = kva & PAGE_MASK; 1756 kva = trunc_page(kva); 1757 size = round_page(size + ofs); 1758 map = kernel_map; 1759 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1760 &obj, &pindex, &prot, &wired); 1761 if (rv != KERN_SUCCESS) 1762 return (EINVAL); 1763 if (entry->start != kva || entry->end != kva + size) { 1764 vm_map_lookup_done(map, entry); 1765 return (EINVAL); 1766 } 1767 vm_map_lookup_done(map, entry); 1768 if (obj != shmfd->shm_object) 1769 return (EINVAL); 1770 vm_map_remove(map, kva, kva + size); 1771 VM_OBJECT_WLOCK(obj); 1772 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1773 shmfd->shm_kmappings--; 1774 VM_OBJECT_WUNLOCK(obj); 1775 return (0); 1776 } 1777 1778 static int 1779 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1780 { 1781 const char *path, *pr_path; 1782 size_t pr_pathlen; 1783 bool visible; 1784 1785 sx_assert(&shm_dict_lock, SA_LOCKED); 1786 kif->kf_type = KF_TYPE_SHM; 1787 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1788 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1789 if (shmfd->shm_path != NULL) { 1790 if (shmfd->shm_path != NULL) { 1791 path = shmfd->shm_path; 1792 pr_path = curthread->td_ucred->cr_prison->pr_path; 1793 if (strcmp(pr_path, "/") != 0) { 1794 /* Return the jail-rooted pathname. */ 1795 pr_pathlen = strlen(pr_path); 1796 visible = strncmp(path, pr_path, pr_pathlen) 1797 == 0 && path[pr_pathlen] == '/'; 1798 if (list && !visible) 1799 return (EPERM); 1800 if (visible) 1801 path += pr_pathlen; 1802 } 1803 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1804 } 1805 } 1806 return (0); 1807 } 1808 1809 static int 1810 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1811 struct filedesc *fdp __unused) 1812 { 1813 int res; 1814 1815 sx_slock(&shm_dict_lock); 1816 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1817 sx_sunlock(&shm_dict_lock); 1818 return (res); 1819 } 1820 1821 static int 1822 shm_add_seals(struct file *fp, int seals) 1823 { 1824 struct shmfd *shmfd; 1825 void *rl_cookie; 1826 vm_ooffset_t writemappings; 1827 int error, nseals; 1828 1829 error = 0; 1830 shmfd = fp->f_data; 1831 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1832 &shmfd->shm_mtx); 1833 1834 /* Even already-set seals should result in EPERM. */ 1835 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1836 error = EPERM; 1837 goto out; 1838 } 1839 nseals = seals & ~shmfd->shm_seals; 1840 if ((nseals & F_SEAL_WRITE) != 0) { 1841 /* 1842 * The rangelock above prevents writable mappings from being 1843 * added after we've started applying seals. The RLOCK here 1844 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1845 * writemappings will be done without a rangelock. 1846 */ 1847 VM_OBJECT_RLOCK(shmfd->shm_object); 1848 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1849 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1850 /* kmappings are also writable */ 1851 if (writemappings > 0) { 1852 error = EBUSY; 1853 goto out; 1854 } 1855 } 1856 shmfd->shm_seals |= nseals; 1857 out: 1858 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1859 return (error); 1860 } 1861 1862 static int 1863 shm_get_seals(struct file *fp, int *seals) 1864 { 1865 struct shmfd *shmfd; 1866 1867 shmfd = fp->f_data; 1868 *seals = shmfd->shm_seals; 1869 return (0); 1870 } 1871 1872 static int 1873 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 1874 { 1875 void *rl_cookie; 1876 struct shmfd *shmfd; 1877 size_t size; 1878 int error; 1879 1880 /* This assumes that the caller already checked for overflow. */ 1881 error = 0; 1882 shmfd = fp->f_data; 1883 size = offset + len; 1884 1885 /* 1886 * Just grab the rangelock for the range that we may be attempting to 1887 * grow, rather than blocking read/write for regions we won't be 1888 * touching while this (potential) resize is in progress. Other 1889 * attempts to resize the shmfd will have to take a write lock from 0 to 1890 * OFF_MAX, so this being potentially beyond the current usable range of 1891 * the shmfd is not necessarily a concern. If other mechanisms are 1892 * added to grow a shmfd, this may need to be re-evaluated. 1893 */ 1894 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 1895 &shmfd->shm_mtx); 1896 if (size > shmfd->shm_size) 1897 error = shm_dotruncate_cookie(shmfd, size, rl_cookie); 1898 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1899 /* Translate to posix_fallocate(2) return value as needed. */ 1900 if (error == ENOMEM) 1901 error = ENOSPC; 1902 return (error); 1903 } 1904 1905 static int 1906 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1907 { 1908 struct shm_mapping *shmm; 1909 struct sbuf sb; 1910 struct kinfo_file kif; 1911 u_long i; 1912 ssize_t curlen; 1913 int error, error2; 1914 1915 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1916 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1917 curlen = 0; 1918 error = 0; 1919 sx_slock(&shm_dict_lock); 1920 for (i = 0; i < shm_hash + 1; i++) { 1921 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1922 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1923 &kif, true); 1924 if (error == EPERM) 1925 continue; 1926 if (error != 0) 1927 break; 1928 pack_kinfo(&kif); 1929 if (req->oldptr != NULL && 1930 kif.kf_structsize + curlen > req->oldlen) 1931 break; 1932 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1933 0 : ENOMEM; 1934 if (error != 0) 1935 break; 1936 curlen += kif.kf_structsize; 1937 } 1938 } 1939 sx_sunlock(&shm_dict_lock); 1940 error2 = sbuf_finish(&sb); 1941 sbuf_delete(&sb); 1942 return (error != 0 ? error : error2); 1943 } 1944 1945 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1946 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1947 NULL, 0, sysctl_posix_shm_list, "", 1948 "POSIX SHM list"); 1949 1950 int 1951 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1952 struct filecaps *caps) 1953 { 1954 1955 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1956 } 1957 1958 /* 1959 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1960 * caller, and libc will enforce it for the traditional shm_open() call. This 1961 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1962 * interface also includes a 'name' argument that is currently unused, but could 1963 * potentially be exported later via some interface for debugging purposes. 1964 * From the kernel's perspective, it is optional. Individual consumers like 1965 * memfd_create() may require it in order to be compatible with other systems 1966 * implementing the same function. 1967 */ 1968 int 1969 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1970 { 1971 1972 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1973 uap->shmflags, NULL, uap->name)); 1974 } 1975