1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * Portions of this software were developed by BAE Systems, the University of 8 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 9 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 10 * Computing (TC) research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * Support for shared swap-backed anonymous memory objects via 36 * shm_open(2), shm_rename(2), and shm_unlink(2). 37 * While most of the implementation is here, vm_mmap.c contains 38 * mapping logic changes. 39 * 40 * posixshmcontrol(1) allows users to inspect the state of the memory 41 * objects. Per-uid swap resource limit controls total amount of 42 * memory that user can consume for anonymous objects, including 43 * shared. 44 */ 45 46 #include <sys/cdefs.h> 47 __FBSDID("$FreeBSD$"); 48 49 #include "opt_capsicum.h" 50 #include "opt_ktrace.h" 51 52 #include <sys/param.h> 53 #include <sys/capsicum.h> 54 #include <sys/conf.h> 55 #include <sys/fcntl.h> 56 #include <sys/file.h> 57 #include <sys/filedesc.h> 58 #include <sys/filio.h> 59 #include <sys/fnv_hash.h> 60 #include <sys/kernel.h> 61 #include <sys/limits.h> 62 #include <sys/uio.h> 63 #include <sys/signal.h> 64 #include <sys/jail.h> 65 #include <sys/ktrace.h> 66 #include <sys/lock.h> 67 #include <sys/malloc.h> 68 #include <sys/mman.h> 69 #include <sys/mutex.h> 70 #include <sys/priv.h> 71 #include <sys/proc.h> 72 #include <sys/refcount.h> 73 #include <sys/resourcevar.h> 74 #include <sys/rwlock.h> 75 #include <sys/sbuf.h> 76 #include <sys/stat.h> 77 #include <sys/syscallsubr.h> 78 #include <sys/sysctl.h> 79 #include <sys/sysproto.h> 80 #include <sys/systm.h> 81 #include <sys/sx.h> 82 #include <sys/time.h> 83 #include <sys/vnode.h> 84 #include <sys/unistd.h> 85 #include <sys/user.h> 86 87 #include <security/audit/audit.h> 88 #include <security/mac/mac_framework.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_extern.h> 94 #include <vm/vm_map.h> 95 #include <vm/vm_kern.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_page.h> 98 #include <vm/vm_pageout.h> 99 #include <vm/vm_pager.h> 100 #include <vm/swap_pager.h> 101 102 struct shm_mapping { 103 char *sm_path; 104 Fnv32_t sm_fnv; 105 struct shmfd *sm_shmfd; 106 LIST_ENTRY(shm_mapping) sm_link; 107 }; 108 109 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 110 static LIST_HEAD(, shm_mapping) *shm_dictionary; 111 static struct sx shm_dict_lock; 112 static struct mtx shm_timestamp_lock; 113 static u_long shm_hash; 114 static struct unrhdr64 shm_ino_unr; 115 static dev_t shm_dev_ino; 116 117 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 118 119 static void shm_init(void *arg); 120 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 121 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 122 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 123 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 124 void *rl_cookie); 125 static int shm_copyin_path(struct thread *td, const char *userpath_in, 126 char **path_out); 127 128 static fo_rdwr_t shm_read; 129 static fo_rdwr_t shm_write; 130 static fo_truncate_t shm_truncate; 131 static fo_ioctl_t shm_ioctl; 132 static fo_stat_t shm_stat; 133 static fo_close_t shm_close; 134 static fo_chmod_t shm_chmod; 135 static fo_chown_t shm_chown; 136 static fo_seek_t shm_seek; 137 static fo_fill_kinfo_t shm_fill_kinfo; 138 static fo_mmap_t shm_mmap; 139 static fo_get_seals_t shm_get_seals; 140 static fo_add_seals_t shm_add_seals; 141 static fo_fallocate_t shm_fallocate; 142 143 /* File descriptor operations. */ 144 struct fileops shm_ops = { 145 .fo_read = shm_read, 146 .fo_write = shm_write, 147 .fo_truncate = shm_truncate, 148 .fo_ioctl = shm_ioctl, 149 .fo_poll = invfo_poll, 150 .fo_kqfilter = invfo_kqfilter, 151 .fo_stat = shm_stat, 152 .fo_close = shm_close, 153 .fo_chmod = shm_chmod, 154 .fo_chown = shm_chown, 155 .fo_sendfile = vn_sendfile, 156 .fo_seek = shm_seek, 157 .fo_fill_kinfo = shm_fill_kinfo, 158 .fo_mmap = shm_mmap, 159 .fo_get_seals = shm_get_seals, 160 .fo_add_seals = shm_add_seals, 161 .fo_fallocate = shm_fallocate, 162 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 163 }; 164 165 FEATURE(posix_shm, "POSIX shared memory"); 166 167 static int 168 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 169 { 170 vm_page_t m; 171 vm_pindex_t idx; 172 size_t tlen; 173 int error, offset, rv; 174 175 idx = OFF_TO_IDX(uio->uio_offset); 176 offset = uio->uio_offset & PAGE_MASK; 177 tlen = MIN(PAGE_SIZE - offset, len); 178 179 rv = vm_page_grab_valid_unlocked(&m, obj, idx, 180 VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOCREAT); 181 if (rv == VM_PAGER_OK) 182 goto found; 183 184 /* 185 * Read I/O without either a corresponding resident page or swap 186 * page: use zero_region. This is intended to avoid instantiating 187 * pages on read from a sparse region. 188 */ 189 VM_OBJECT_WLOCK(obj); 190 m = vm_page_lookup(obj, idx); 191 if (uio->uio_rw == UIO_READ && m == NULL && 192 !vm_pager_has_page(obj, idx, NULL, NULL)) { 193 VM_OBJECT_WUNLOCK(obj); 194 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 195 } 196 197 /* 198 * Although the tmpfs vnode lock is held here, it is 199 * nonetheless safe to sleep waiting for a free page. The 200 * pageout daemon does not need to acquire the tmpfs vnode 201 * lock to page out tobj's pages because tobj is a OBJT_SWAP 202 * type object. 203 */ 204 rv = vm_page_grab_valid(&m, obj, idx, 205 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 206 if (rv != VM_PAGER_OK) { 207 VM_OBJECT_WUNLOCK(obj); 208 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 209 obj, idx, rv); 210 return (EIO); 211 } 212 VM_OBJECT_WUNLOCK(obj); 213 214 found: 215 error = uiomove_fromphys(&m, offset, tlen, uio); 216 if (uio->uio_rw == UIO_WRITE && error == 0) 217 vm_page_set_dirty(m); 218 vm_page_activate(m); 219 vm_page_sunbusy(m); 220 221 return (error); 222 } 223 224 int 225 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 226 { 227 ssize_t resid; 228 size_t len; 229 int error; 230 231 error = 0; 232 while ((resid = uio->uio_resid) > 0) { 233 if (obj_size <= uio->uio_offset) 234 break; 235 len = MIN(obj_size - uio->uio_offset, resid); 236 if (len == 0) 237 break; 238 error = uiomove_object_page(obj, len, uio); 239 if (error != 0 || resid == uio->uio_resid) 240 break; 241 } 242 return (error); 243 } 244 245 static int 246 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 247 { 248 struct shmfd *shmfd; 249 off_t foffset; 250 int error; 251 252 shmfd = fp->f_data; 253 foffset = foffset_lock(fp, 0); 254 error = 0; 255 switch (whence) { 256 case L_INCR: 257 if (foffset < 0 || 258 (offset > 0 && foffset > OFF_MAX - offset)) { 259 error = EOVERFLOW; 260 break; 261 } 262 offset += foffset; 263 break; 264 case L_XTND: 265 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 266 error = EOVERFLOW; 267 break; 268 } 269 offset += shmfd->shm_size; 270 break; 271 case L_SET: 272 break; 273 default: 274 error = EINVAL; 275 } 276 if (error == 0) { 277 if (offset < 0 || offset > shmfd->shm_size) 278 error = EINVAL; 279 else 280 td->td_uretoff.tdu_off = offset; 281 } 282 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 283 return (error); 284 } 285 286 static int 287 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 288 int flags, struct thread *td) 289 { 290 struct shmfd *shmfd; 291 void *rl_cookie; 292 int error; 293 294 shmfd = fp->f_data; 295 #ifdef MAC 296 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 297 if (error) 298 return (error); 299 #endif 300 foffset_lock_uio(fp, uio, flags); 301 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 302 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 303 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 304 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 305 foffset_unlock_uio(fp, uio, flags); 306 return (error); 307 } 308 309 static int 310 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 311 int flags, struct thread *td) 312 { 313 struct shmfd *shmfd; 314 void *rl_cookie; 315 int error; 316 off_t size; 317 318 shmfd = fp->f_data; 319 #ifdef MAC 320 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 321 if (error) 322 return (error); 323 #endif 324 foffset_lock_uio(fp, uio, flags); 325 if (uio->uio_resid > OFF_MAX - uio->uio_offset) { 326 /* 327 * Overflow is only an error if we're supposed to expand on 328 * write. Otherwise, we'll just truncate the write to the 329 * size of the file, which can only grow up to OFF_MAX. 330 */ 331 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0) { 332 foffset_unlock_uio(fp, uio, flags); 333 return (EFBIG); 334 } 335 336 size = shmfd->shm_size; 337 } else { 338 size = uio->uio_offset + uio->uio_resid; 339 } 340 if ((flags & FOF_OFFSET) == 0) { 341 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 342 &shmfd->shm_mtx); 343 } else { 344 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 345 size, &shmfd->shm_mtx); 346 } 347 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) { 348 error = EPERM; 349 } else { 350 error = 0; 351 if ((shmfd->shm_flags & SHM_GROW_ON_WRITE) != 0 && 352 size > shmfd->shm_size) { 353 VM_OBJECT_WLOCK(shmfd->shm_object); 354 error = shm_dotruncate_locked(shmfd, size, rl_cookie); 355 VM_OBJECT_WUNLOCK(shmfd->shm_object); 356 } 357 if (error == 0) 358 error = uiomove_object(shmfd->shm_object, 359 shmfd->shm_size, uio); 360 } 361 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 362 foffset_unlock_uio(fp, uio, flags); 363 return (error); 364 } 365 366 static int 367 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 368 struct thread *td) 369 { 370 struct shmfd *shmfd; 371 #ifdef MAC 372 int error; 373 #endif 374 375 shmfd = fp->f_data; 376 #ifdef MAC 377 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 378 if (error) 379 return (error); 380 #endif 381 return (shm_dotruncate(shmfd, length)); 382 } 383 384 int 385 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 386 struct thread *td) 387 { 388 389 switch (com) { 390 case FIONBIO: 391 case FIOASYNC: 392 /* 393 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 394 * just like it would on an unlinked regular file 395 */ 396 return (0); 397 default: 398 return (ENOTTY); 399 } 400 } 401 402 static int 403 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 404 struct thread *td) 405 { 406 struct shmfd *shmfd; 407 #ifdef MAC 408 int error; 409 #endif 410 411 shmfd = fp->f_data; 412 413 #ifdef MAC 414 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 415 if (error) 416 return (error); 417 #endif 418 419 /* 420 * Attempt to return sanish values for fstat() on a memory file 421 * descriptor. 422 */ 423 bzero(sb, sizeof(*sb)); 424 sb->st_blksize = PAGE_SIZE; 425 sb->st_size = shmfd->shm_size; 426 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 427 mtx_lock(&shm_timestamp_lock); 428 sb->st_atim = shmfd->shm_atime; 429 sb->st_ctim = shmfd->shm_ctime; 430 sb->st_mtim = shmfd->shm_mtime; 431 sb->st_birthtim = shmfd->shm_birthtime; 432 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 433 sb->st_uid = shmfd->shm_uid; 434 sb->st_gid = shmfd->shm_gid; 435 mtx_unlock(&shm_timestamp_lock); 436 sb->st_dev = shm_dev_ino; 437 sb->st_ino = shmfd->shm_ino; 438 sb->st_nlink = shmfd->shm_object->ref_count; 439 440 return (0); 441 } 442 443 static int 444 shm_close(struct file *fp, struct thread *td) 445 { 446 struct shmfd *shmfd; 447 448 shmfd = fp->f_data; 449 fp->f_data = NULL; 450 shm_drop(shmfd); 451 452 return (0); 453 } 454 455 static int 456 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 457 int error; 458 char *path; 459 const char *pr_path; 460 size_t pr_pathlen; 461 462 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 463 pr_path = td->td_ucred->cr_prison->pr_path; 464 465 /* Construct a full pathname for jailed callers. */ 466 pr_pathlen = strcmp(pr_path, "/") == 467 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 468 error = copyinstr(userpath_in, path + pr_pathlen, 469 MAXPATHLEN - pr_pathlen, NULL); 470 if (error != 0) 471 goto out; 472 473 #ifdef KTRACE 474 if (KTRPOINT(curthread, KTR_NAMEI)) 475 ktrnamei(path); 476 #endif 477 478 /* Require paths to start with a '/' character. */ 479 if (path[pr_pathlen] != '/') { 480 error = EINVAL; 481 goto out; 482 } 483 484 *path_out = path; 485 486 out: 487 if (error != 0) 488 free(path, M_SHMFD); 489 490 return (error); 491 } 492 493 static int 494 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 495 { 496 vm_object_t object; 497 vm_page_t m; 498 vm_pindex_t idx, nobjsize; 499 vm_ooffset_t delta; 500 int base, rv; 501 502 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 503 object = shmfd->shm_object; 504 VM_OBJECT_ASSERT_WLOCKED(object); 505 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 506 if (length == shmfd->shm_size) 507 return (0); 508 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 509 510 /* Are we shrinking? If so, trim the end. */ 511 if (length < shmfd->shm_size) { 512 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 513 return (EPERM); 514 515 /* 516 * Disallow any requests to shrink the size if this 517 * object is mapped into the kernel. 518 */ 519 if (shmfd->shm_kmappings > 0) 520 return (EBUSY); 521 522 /* 523 * Zero the truncated part of the last page. 524 */ 525 base = length & PAGE_MASK; 526 if (base != 0) { 527 idx = OFF_TO_IDX(length); 528 retry: 529 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 530 if (m != NULL) { 531 MPASS(vm_page_all_valid(m)); 532 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 533 m = vm_page_alloc(object, idx, 534 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 535 if (m == NULL) 536 goto retry; 537 vm_object_pip_add(object, 1); 538 VM_OBJECT_WUNLOCK(object); 539 rv = vm_pager_get_pages(object, &m, 1, NULL, 540 NULL); 541 VM_OBJECT_WLOCK(object); 542 vm_object_pip_wakeup(object); 543 if (rv == VM_PAGER_OK) { 544 /* 545 * Since the page was not resident, 546 * and therefore not recently 547 * accessed, immediately enqueue it 548 * for asynchronous laundering. The 549 * current operation is not regarded 550 * as an access. 551 */ 552 vm_page_launder(m); 553 } else { 554 vm_page_free(m); 555 VM_OBJECT_WUNLOCK(object); 556 return (EIO); 557 } 558 } 559 if (m != NULL) { 560 pmap_zero_page_area(m, base, PAGE_SIZE - base); 561 KASSERT(vm_page_all_valid(m), 562 ("shm_dotruncate: page %p is invalid", m)); 563 vm_page_set_dirty(m); 564 vm_page_xunbusy(m); 565 } 566 } 567 delta = IDX_TO_OFF(object->size - nobjsize); 568 569 if (nobjsize < object->size) 570 vm_object_page_remove(object, nobjsize, object->size, 571 0); 572 573 /* Free the swap accounted for shm */ 574 swap_release_by_cred(delta, object->cred); 575 object->charge -= delta; 576 } else { 577 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 578 return (EPERM); 579 580 /* Try to reserve additional swap space. */ 581 delta = IDX_TO_OFF(nobjsize - object->size); 582 if (!swap_reserve_by_cred(delta, object->cred)) 583 return (ENOMEM); 584 object->charge += delta; 585 } 586 shmfd->shm_size = length; 587 mtx_lock(&shm_timestamp_lock); 588 vfs_timestamp(&shmfd->shm_ctime); 589 shmfd->shm_mtime = shmfd->shm_ctime; 590 mtx_unlock(&shm_timestamp_lock); 591 object->size = nobjsize; 592 return (0); 593 } 594 595 int 596 shm_dotruncate(struct shmfd *shmfd, off_t length) 597 { 598 void *rl_cookie; 599 int error; 600 601 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 602 &shmfd->shm_mtx); 603 VM_OBJECT_WLOCK(shmfd->shm_object); 604 error = shm_dotruncate_locked(shmfd, length, rl_cookie); 605 VM_OBJECT_WUNLOCK(shmfd->shm_object); 606 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 607 return (error); 608 } 609 610 /* 611 * shmfd object management including creation and reference counting 612 * routines. 613 */ 614 struct shmfd * 615 shm_alloc(struct ucred *ucred, mode_t mode) 616 { 617 struct shmfd *shmfd; 618 619 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 620 shmfd->shm_size = 0; 621 shmfd->shm_uid = ucred->cr_uid; 622 shmfd->shm_gid = ucred->cr_gid; 623 shmfd->shm_mode = mode; 624 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 625 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 626 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 627 vfs_timestamp(&shmfd->shm_birthtime); 628 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 629 shmfd->shm_birthtime; 630 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 631 refcount_init(&shmfd->shm_refs, 1); 632 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 633 rangelock_init(&shmfd->shm_rl); 634 #ifdef MAC 635 mac_posixshm_init(shmfd); 636 mac_posixshm_create(ucred, shmfd); 637 #endif 638 639 return (shmfd); 640 } 641 642 struct shmfd * 643 shm_hold(struct shmfd *shmfd) 644 { 645 646 refcount_acquire(&shmfd->shm_refs); 647 return (shmfd); 648 } 649 650 void 651 shm_drop(struct shmfd *shmfd) 652 { 653 654 if (refcount_release(&shmfd->shm_refs)) { 655 #ifdef MAC 656 mac_posixshm_destroy(shmfd); 657 #endif 658 rangelock_destroy(&shmfd->shm_rl); 659 mtx_destroy(&shmfd->shm_mtx); 660 vm_object_deallocate(shmfd->shm_object); 661 free(shmfd, M_SHMFD); 662 } 663 } 664 665 /* 666 * Determine if the credentials have sufficient permissions for a 667 * specified combination of FREAD and FWRITE. 668 */ 669 int 670 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 671 { 672 accmode_t accmode; 673 int error; 674 675 accmode = 0; 676 if (flags & FREAD) 677 accmode |= VREAD; 678 if (flags & FWRITE) 679 accmode |= VWRITE; 680 mtx_lock(&shm_timestamp_lock); 681 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 682 accmode, ucred, NULL); 683 mtx_unlock(&shm_timestamp_lock); 684 return (error); 685 } 686 687 /* 688 * Dictionary management. We maintain an in-kernel dictionary to map 689 * paths to shmfd objects. We use the FNV hash on the path to store 690 * the mappings in a hash table. 691 */ 692 static void 693 shm_init(void *arg) 694 { 695 696 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 697 sx_init(&shm_dict_lock, "shm dictionary"); 698 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 699 new_unrhdr64(&shm_ino_unr, 1); 700 shm_dev_ino = devfs_alloc_cdp_inode(); 701 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 702 } 703 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 704 705 static struct shmfd * 706 shm_lookup(char *path, Fnv32_t fnv) 707 { 708 struct shm_mapping *map; 709 710 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 711 if (map->sm_fnv != fnv) 712 continue; 713 if (strcmp(map->sm_path, path) == 0) 714 return (map->sm_shmfd); 715 } 716 717 return (NULL); 718 } 719 720 static void 721 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 722 { 723 struct shm_mapping *map; 724 725 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 726 map->sm_path = path; 727 map->sm_fnv = fnv; 728 map->sm_shmfd = shm_hold(shmfd); 729 shmfd->shm_path = path; 730 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 731 } 732 733 static int 734 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 735 { 736 struct shm_mapping *map; 737 int error; 738 739 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 740 if (map->sm_fnv != fnv) 741 continue; 742 if (strcmp(map->sm_path, path) == 0) { 743 #ifdef MAC 744 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 745 if (error) 746 return (error); 747 #endif 748 error = shm_access(map->sm_shmfd, ucred, 749 FREAD | FWRITE); 750 if (error) 751 return (error); 752 map->sm_shmfd->shm_path = NULL; 753 LIST_REMOVE(map, sm_link); 754 shm_drop(map->sm_shmfd); 755 free(map->sm_path, M_SHMFD); 756 free(map, M_SHMFD); 757 return (0); 758 } 759 } 760 761 return (ENOENT); 762 } 763 764 int 765 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 766 int shmflags, struct filecaps *fcaps, const char *name __unused) 767 { 768 struct filedesc *fdp; 769 struct shmfd *shmfd; 770 struct file *fp; 771 char *path; 772 void *rl_cookie; 773 Fnv32_t fnv; 774 mode_t cmode; 775 int error, fd, initial_seals; 776 777 if ((shmflags & ~(SHM_ALLOW_SEALING | SHM_GROW_ON_WRITE)) != 0) 778 return (EINVAL); 779 780 initial_seals = F_SEAL_SEAL; 781 if ((shmflags & SHM_ALLOW_SEALING) != 0) 782 initial_seals &= ~F_SEAL_SEAL; 783 784 #ifdef CAPABILITY_MODE 785 /* 786 * shm_open(2) is only allowed for anonymous objects. 787 */ 788 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 789 return (ECAPMODE); 790 #endif 791 792 AUDIT_ARG_FFLAGS(flags); 793 AUDIT_ARG_MODE(mode); 794 795 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 796 return (EINVAL); 797 798 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 799 return (EINVAL); 800 801 /* 802 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 803 * If the decision is made later to allow additional seals, care must be 804 * taken below to ensure that the seals are properly set if the shmfd 805 * already existed -- this currently assumes that only F_SEAL_SEAL can 806 * be set and doesn't take further precautions to ensure the validity of 807 * the seals being added with respect to current mappings. 808 */ 809 if ((initial_seals & ~F_SEAL_SEAL) != 0) 810 return (EINVAL); 811 812 fdp = td->td_proc->p_fd; 813 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 814 815 /* 816 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 817 * by POSIX. We allow it to be unset here so that an in-kernel 818 * interface may be written as a thin layer around shm, optionally not 819 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 820 * in sys_shm_open() to keep this implementation compliant. 821 */ 822 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 823 if (error) 824 return (error); 825 826 /* A SHM_ANON path pointer creates an anonymous object. */ 827 if (userpath == SHM_ANON) { 828 /* A read-only anonymous object is pointless. */ 829 if ((flags & O_ACCMODE) == O_RDONLY) { 830 fdclose(td, fp, fd); 831 fdrop(fp, td); 832 return (EINVAL); 833 } 834 shmfd = shm_alloc(td->td_ucred, cmode); 835 shmfd->shm_seals = initial_seals; 836 } else { 837 error = shm_copyin_path(td, userpath, &path); 838 if (error != 0) { 839 fdclose(td, fp, fd); 840 fdrop(fp, td); 841 return (error); 842 } 843 844 AUDIT_ARG_UPATH1_CANON(path); 845 fnv = fnv_32_str(path, FNV1_32_INIT); 846 sx_xlock(&shm_dict_lock); 847 shmfd = shm_lookup(path, fnv); 848 if (shmfd == NULL) { 849 /* Object does not yet exist, create it if requested. */ 850 if (flags & O_CREAT) { 851 #ifdef MAC 852 error = mac_posixshm_check_create(td->td_ucred, 853 path); 854 if (error == 0) { 855 #endif 856 shmfd = shm_alloc(td->td_ucred, cmode); 857 shmfd->shm_seals = initial_seals; 858 shm_insert(path, fnv, shmfd); 859 #ifdef MAC 860 } 861 #endif 862 } else { 863 free(path, M_SHMFD); 864 error = ENOENT; 865 } 866 } else { 867 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 868 &shmfd->shm_mtx); 869 870 /* 871 * kern_shm_open() likely shouldn't ever error out on 872 * trying to set a seal that already exists, unlike 873 * F_ADD_SEALS. This would break terribly as 874 * shm_open(2) actually sets F_SEAL_SEAL to maintain 875 * historical behavior where the underlying file could 876 * not be sealed. 877 */ 878 initial_seals &= ~shmfd->shm_seals; 879 880 /* 881 * Object already exists, obtain a new 882 * reference if requested and permitted. 883 */ 884 free(path, M_SHMFD); 885 886 /* 887 * initial_seals can't set additional seals if we've 888 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 889 * then we've already removed that one from 890 * initial_seals. This is currently redundant as we 891 * only allow setting F_SEAL_SEAL at creation time, but 892 * it's cheap to check and decreases the effort required 893 * to allow additional seals. 894 */ 895 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 896 initial_seals != 0) 897 error = EPERM; 898 else if ((flags & (O_CREAT | O_EXCL)) == 899 (O_CREAT | O_EXCL)) 900 error = EEXIST; 901 else { 902 #ifdef MAC 903 error = mac_posixshm_check_open(td->td_ucred, 904 shmfd, FFLAGS(flags & O_ACCMODE)); 905 if (error == 0) 906 #endif 907 error = shm_access(shmfd, td->td_ucred, 908 FFLAGS(flags & O_ACCMODE)); 909 } 910 911 /* 912 * Truncate the file back to zero length if 913 * O_TRUNC was specified and the object was 914 * opened with read/write. 915 */ 916 if (error == 0 && 917 (flags & (O_ACCMODE | O_TRUNC)) == 918 (O_RDWR | O_TRUNC)) { 919 VM_OBJECT_WLOCK(shmfd->shm_object); 920 #ifdef MAC 921 error = mac_posixshm_check_truncate( 922 td->td_ucred, fp->f_cred, shmfd); 923 if (error == 0) 924 #endif 925 error = shm_dotruncate_locked(shmfd, 0, 926 rl_cookie); 927 VM_OBJECT_WUNLOCK(shmfd->shm_object); 928 } 929 if (error == 0) { 930 /* 931 * Currently we only allow F_SEAL_SEAL to be 932 * set initially. As noted above, this would 933 * need to be reworked should that change. 934 */ 935 shmfd->shm_seals |= initial_seals; 936 shm_hold(shmfd); 937 } 938 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 939 &shmfd->shm_mtx); 940 } 941 sx_xunlock(&shm_dict_lock); 942 943 if (error) { 944 fdclose(td, fp, fd); 945 fdrop(fp, td); 946 return (error); 947 } 948 } 949 950 shmfd->shm_flags = shmflags; 951 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 952 953 td->td_retval[0] = fd; 954 fdrop(fp, td); 955 956 return (0); 957 } 958 959 /* System calls. */ 960 #ifdef COMPAT_FREEBSD12 961 int 962 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 963 { 964 965 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 966 uap->mode, NULL)); 967 } 968 #endif 969 970 int 971 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 972 { 973 char *path; 974 Fnv32_t fnv; 975 int error; 976 977 error = shm_copyin_path(td, uap->path, &path); 978 if (error != 0) 979 return (error); 980 981 AUDIT_ARG_UPATH1_CANON(path); 982 fnv = fnv_32_str(path, FNV1_32_INIT); 983 sx_xlock(&shm_dict_lock); 984 error = shm_remove(path, fnv, td->td_ucred); 985 sx_xunlock(&shm_dict_lock); 986 free(path, M_SHMFD); 987 988 return (error); 989 } 990 991 int 992 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 993 { 994 char *path_from = NULL, *path_to = NULL; 995 Fnv32_t fnv_from, fnv_to; 996 struct shmfd *fd_from; 997 struct shmfd *fd_to; 998 int error; 999 int flags; 1000 1001 flags = uap->flags; 1002 AUDIT_ARG_FFLAGS(flags); 1003 1004 /* 1005 * Make sure the user passed only valid flags. 1006 * If you add a new flag, please add a new term here. 1007 */ 1008 if ((flags & ~( 1009 SHM_RENAME_NOREPLACE | 1010 SHM_RENAME_EXCHANGE 1011 )) != 0) { 1012 error = EINVAL; 1013 goto out; 1014 } 1015 1016 /* 1017 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 1018 * force the user to choose one or the other. 1019 */ 1020 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 1021 (flags & SHM_RENAME_EXCHANGE) != 0) { 1022 error = EINVAL; 1023 goto out; 1024 } 1025 1026 /* Renaming to or from anonymous makes no sense */ 1027 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 1028 error = EINVAL; 1029 goto out; 1030 } 1031 1032 error = shm_copyin_path(td, uap->path_from, &path_from); 1033 if (error != 0) 1034 goto out; 1035 1036 error = shm_copyin_path(td, uap->path_to, &path_to); 1037 if (error != 0) 1038 goto out; 1039 1040 AUDIT_ARG_UPATH1_CANON(path_from); 1041 AUDIT_ARG_UPATH2_CANON(path_to); 1042 1043 /* Rename with from/to equal is a no-op */ 1044 if (strcmp(path_from, path_to) == 0) 1045 goto out; 1046 1047 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1048 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1049 1050 sx_xlock(&shm_dict_lock); 1051 1052 fd_from = shm_lookup(path_from, fnv_from); 1053 if (fd_from == NULL) { 1054 error = ENOENT; 1055 goto out_locked; 1056 } 1057 1058 fd_to = shm_lookup(path_to, fnv_to); 1059 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1060 error = EEXIST; 1061 goto out_locked; 1062 } 1063 1064 /* 1065 * Unconditionally prevents shm_remove from invalidating the 'from' 1066 * shm's state. 1067 */ 1068 shm_hold(fd_from); 1069 error = shm_remove(path_from, fnv_from, td->td_ucred); 1070 1071 /* 1072 * One of my assumptions failed if ENOENT (e.g. locking didn't 1073 * protect us) 1074 */ 1075 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1076 path_from)); 1077 if (error != 0) { 1078 shm_drop(fd_from); 1079 goto out_locked; 1080 } 1081 1082 /* 1083 * If we are exchanging, we need to ensure the shm_remove below 1084 * doesn't invalidate the dest shm's state. 1085 */ 1086 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1087 shm_hold(fd_to); 1088 1089 /* 1090 * NOTE: if path_to is not already in the hash, c'est la vie; 1091 * it simply means we have nothing already at path_to to unlink. 1092 * That is the ENOENT case. 1093 * 1094 * If we somehow don't have access to unlink this guy, but 1095 * did for the shm at path_from, then relink the shm to path_from 1096 * and abort with EACCES. 1097 * 1098 * All other errors: that is weird; let's relink and abort the 1099 * operation. 1100 */ 1101 error = shm_remove(path_to, fnv_to, td->td_ucred); 1102 if (error != 0 && error != ENOENT) { 1103 shm_insert(path_from, fnv_from, fd_from); 1104 shm_drop(fd_from); 1105 /* Don't free path_from now, since the hash references it */ 1106 path_from = NULL; 1107 goto out_locked; 1108 } 1109 1110 error = 0; 1111 1112 shm_insert(path_to, fnv_to, fd_from); 1113 1114 /* Don't free path_to now, since the hash references it */ 1115 path_to = NULL; 1116 1117 /* We kept a ref when we removed, and incremented again in insert */ 1118 shm_drop(fd_from); 1119 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1120 fd_from->shm_refs)); 1121 1122 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1123 shm_insert(path_from, fnv_from, fd_to); 1124 path_from = NULL; 1125 shm_drop(fd_to); 1126 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1127 fd_to->shm_refs)); 1128 } 1129 1130 out_locked: 1131 sx_xunlock(&shm_dict_lock); 1132 1133 out: 1134 free(path_from, M_SHMFD); 1135 free(path_to, M_SHMFD); 1136 return (error); 1137 } 1138 1139 int 1140 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1141 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1142 vm_ooffset_t foff, struct thread *td) 1143 { 1144 struct shmfd *shmfd; 1145 vm_prot_t maxprot; 1146 int error; 1147 bool writecnt; 1148 void *rl_cookie; 1149 1150 shmfd = fp->f_data; 1151 maxprot = VM_PROT_NONE; 1152 1153 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1154 &shmfd->shm_mtx); 1155 /* FREAD should always be set. */ 1156 if ((fp->f_flag & FREAD) != 0) 1157 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1158 1159 /* 1160 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1161 * mapping with a write seal applied. Private mappings are always 1162 * writeable. 1163 */ 1164 if ((flags & MAP_SHARED) == 0) { 1165 cap_maxprot |= VM_PROT_WRITE; 1166 maxprot |= VM_PROT_WRITE; 1167 writecnt = false; 1168 } else { 1169 if ((fp->f_flag & FWRITE) != 0 && 1170 (shmfd->shm_seals & F_SEAL_WRITE) == 0) 1171 maxprot |= VM_PROT_WRITE; 1172 1173 /* 1174 * Any mappings from a writable descriptor may be upgraded to 1175 * VM_PROT_WRITE with mprotect(2), unless a write-seal was 1176 * applied between the open and subsequent mmap(2). We want to 1177 * reject application of a write seal as long as any such 1178 * mapping exists so that the seal cannot be trivially bypassed. 1179 */ 1180 writecnt = (maxprot & VM_PROT_WRITE) != 0; 1181 if (!writecnt && (prot & VM_PROT_WRITE) != 0) { 1182 error = EACCES; 1183 goto out; 1184 } 1185 } 1186 maxprot &= cap_maxprot; 1187 1188 /* See comment in vn_mmap(). */ 1189 if ( 1190 #ifdef _LP64 1191 objsize > OFF_MAX || 1192 #endif 1193 foff < 0 || foff > OFF_MAX - objsize) { 1194 error = EINVAL; 1195 goto out; 1196 } 1197 1198 #ifdef MAC 1199 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1200 if (error != 0) 1201 goto out; 1202 #endif 1203 1204 mtx_lock(&shm_timestamp_lock); 1205 vfs_timestamp(&shmfd->shm_atime); 1206 mtx_unlock(&shm_timestamp_lock); 1207 vm_object_reference(shmfd->shm_object); 1208 1209 if (writecnt) 1210 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 1211 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1212 shmfd->shm_object, foff, writecnt, td); 1213 if (error != 0) { 1214 if (writecnt) 1215 vm_pager_release_writecount(shmfd->shm_object, 0, 1216 objsize); 1217 vm_object_deallocate(shmfd->shm_object); 1218 } 1219 out: 1220 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1221 return (error); 1222 } 1223 1224 static int 1225 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1226 struct thread *td) 1227 { 1228 struct shmfd *shmfd; 1229 int error; 1230 1231 error = 0; 1232 shmfd = fp->f_data; 1233 mtx_lock(&shm_timestamp_lock); 1234 /* 1235 * SUSv4 says that x bits of permission need not be affected. 1236 * Be consistent with our shm_open there. 1237 */ 1238 #ifdef MAC 1239 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1240 if (error != 0) 1241 goto out; 1242 #endif 1243 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 1244 shmfd->shm_gid, VADMIN, active_cred, NULL); 1245 if (error != 0) 1246 goto out; 1247 shmfd->shm_mode = mode & ACCESSPERMS; 1248 out: 1249 mtx_unlock(&shm_timestamp_lock); 1250 return (error); 1251 } 1252 1253 static int 1254 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1255 struct thread *td) 1256 { 1257 struct shmfd *shmfd; 1258 int error; 1259 1260 error = 0; 1261 shmfd = fp->f_data; 1262 mtx_lock(&shm_timestamp_lock); 1263 #ifdef MAC 1264 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1265 if (error != 0) 1266 goto out; 1267 #endif 1268 if (uid == (uid_t)-1) 1269 uid = shmfd->shm_uid; 1270 if (gid == (gid_t)-1) 1271 gid = shmfd->shm_gid; 1272 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1273 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1274 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1275 goto out; 1276 shmfd->shm_uid = uid; 1277 shmfd->shm_gid = gid; 1278 out: 1279 mtx_unlock(&shm_timestamp_lock); 1280 return (error); 1281 } 1282 1283 /* 1284 * Helper routines to allow the backing object of a shared memory file 1285 * descriptor to be mapped in the kernel. 1286 */ 1287 int 1288 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1289 { 1290 struct shmfd *shmfd; 1291 vm_offset_t kva, ofs; 1292 vm_object_t obj; 1293 int rv; 1294 1295 if (fp->f_type != DTYPE_SHM) 1296 return (EINVAL); 1297 shmfd = fp->f_data; 1298 obj = shmfd->shm_object; 1299 VM_OBJECT_WLOCK(obj); 1300 /* 1301 * XXXRW: This validation is probably insufficient, and subject to 1302 * sign errors. It should be fixed. 1303 */ 1304 if (offset >= shmfd->shm_size || 1305 offset + size > round_page(shmfd->shm_size)) { 1306 VM_OBJECT_WUNLOCK(obj); 1307 return (EINVAL); 1308 } 1309 1310 shmfd->shm_kmappings++; 1311 vm_object_reference_locked(obj); 1312 VM_OBJECT_WUNLOCK(obj); 1313 1314 /* Map the object into the kernel_map and wire it. */ 1315 kva = vm_map_min(kernel_map); 1316 ofs = offset & PAGE_MASK; 1317 offset = trunc_page(offset); 1318 size = round_page(size + ofs); 1319 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1320 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1321 VM_PROT_READ | VM_PROT_WRITE, 0); 1322 if (rv == KERN_SUCCESS) { 1323 rv = vm_map_wire(kernel_map, kva, kva + size, 1324 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1325 if (rv == KERN_SUCCESS) { 1326 *memp = (void *)(kva + ofs); 1327 return (0); 1328 } 1329 vm_map_remove(kernel_map, kva, kva + size); 1330 } else 1331 vm_object_deallocate(obj); 1332 1333 /* On failure, drop our mapping reference. */ 1334 VM_OBJECT_WLOCK(obj); 1335 shmfd->shm_kmappings--; 1336 VM_OBJECT_WUNLOCK(obj); 1337 1338 return (vm_mmap_to_errno(rv)); 1339 } 1340 1341 /* 1342 * We require the caller to unmap the entire entry. This allows us to 1343 * safely decrement shm_kmappings when a mapping is removed. 1344 */ 1345 int 1346 shm_unmap(struct file *fp, void *mem, size_t size) 1347 { 1348 struct shmfd *shmfd; 1349 vm_map_entry_t entry; 1350 vm_offset_t kva, ofs; 1351 vm_object_t obj; 1352 vm_pindex_t pindex; 1353 vm_prot_t prot; 1354 boolean_t wired; 1355 vm_map_t map; 1356 int rv; 1357 1358 if (fp->f_type != DTYPE_SHM) 1359 return (EINVAL); 1360 shmfd = fp->f_data; 1361 kva = (vm_offset_t)mem; 1362 ofs = kva & PAGE_MASK; 1363 kva = trunc_page(kva); 1364 size = round_page(size + ofs); 1365 map = kernel_map; 1366 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1367 &obj, &pindex, &prot, &wired); 1368 if (rv != KERN_SUCCESS) 1369 return (EINVAL); 1370 if (entry->start != kva || entry->end != kva + size) { 1371 vm_map_lookup_done(map, entry); 1372 return (EINVAL); 1373 } 1374 vm_map_lookup_done(map, entry); 1375 if (obj != shmfd->shm_object) 1376 return (EINVAL); 1377 vm_map_remove(map, kva, kva + size); 1378 VM_OBJECT_WLOCK(obj); 1379 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1380 shmfd->shm_kmappings--; 1381 VM_OBJECT_WUNLOCK(obj); 1382 return (0); 1383 } 1384 1385 static int 1386 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1387 { 1388 const char *path, *pr_path; 1389 size_t pr_pathlen; 1390 bool visible; 1391 1392 sx_assert(&shm_dict_lock, SA_LOCKED); 1393 kif->kf_type = KF_TYPE_SHM; 1394 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1395 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1396 if (shmfd->shm_path != NULL) { 1397 if (shmfd->shm_path != NULL) { 1398 path = shmfd->shm_path; 1399 pr_path = curthread->td_ucred->cr_prison->pr_path; 1400 if (strcmp(pr_path, "/") != 0) { 1401 /* Return the jail-rooted pathname. */ 1402 pr_pathlen = strlen(pr_path); 1403 visible = strncmp(path, pr_path, pr_pathlen) 1404 == 0 && path[pr_pathlen] == '/'; 1405 if (list && !visible) 1406 return (EPERM); 1407 if (visible) 1408 path += pr_pathlen; 1409 } 1410 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1411 } 1412 } 1413 return (0); 1414 } 1415 1416 static int 1417 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1418 struct filedesc *fdp __unused) 1419 { 1420 int res; 1421 1422 sx_slock(&shm_dict_lock); 1423 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1424 sx_sunlock(&shm_dict_lock); 1425 return (res); 1426 } 1427 1428 static int 1429 shm_add_seals(struct file *fp, int seals) 1430 { 1431 struct shmfd *shmfd; 1432 void *rl_cookie; 1433 vm_ooffset_t writemappings; 1434 int error, nseals; 1435 1436 error = 0; 1437 shmfd = fp->f_data; 1438 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1439 &shmfd->shm_mtx); 1440 1441 /* Even already-set seals should result in EPERM. */ 1442 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1443 error = EPERM; 1444 goto out; 1445 } 1446 nseals = seals & ~shmfd->shm_seals; 1447 if ((nseals & F_SEAL_WRITE) != 0) { 1448 /* 1449 * The rangelock above prevents writable mappings from being 1450 * added after we've started applying seals. The RLOCK here 1451 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1452 * writemappings will be done without a rangelock. 1453 */ 1454 VM_OBJECT_RLOCK(shmfd->shm_object); 1455 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1456 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1457 /* kmappings are also writable */ 1458 if (writemappings > 0) { 1459 error = EBUSY; 1460 goto out; 1461 } 1462 } 1463 shmfd->shm_seals |= nseals; 1464 out: 1465 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1466 return (error); 1467 } 1468 1469 static int 1470 shm_get_seals(struct file *fp, int *seals) 1471 { 1472 struct shmfd *shmfd; 1473 1474 shmfd = fp->f_data; 1475 *seals = shmfd->shm_seals; 1476 return (0); 1477 } 1478 1479 static int 1480 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 1481 { 1482 void *rl_cookie; 1483 struct shmfd *shmfd; 1484 size_t size; 1485 int error; 1486 1487 /* This assumes that the caller already checked for overflow. */ 1488 error = 0; 1489 shmfd = fp->f_data; 1490 size = offset + len; 1491 1492 /* 1493 * Just grab the rangelock for the range that we may be attempting to 1494 * grow, rather than blocking read/write for regions we won't be 1495 * touching while this (potential) resize is in progress. Other 1496 * attempts to resize the shmfd will have to take a write lock from 0 to 1497 * OFF_MAX, so this being potentially beyond the current usable range of 1498 * the shmfd is not necessarily a concern. If other mechanisms are 1499 * added to grow a shmfd, this may need to be re-evaluated. 1500 */ 1501 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 1502 &shmfd->shm_mtx); 1503 if (size > shmfd->shm_size) { 1504 VM_OBJECT_WLOCK(shmfd->shm_object); 1505 error = shm_dotruncate_locked(shmfd, size, rl_cookie); 1506 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1507 } 1508 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1509 /* Translate to posix_fallocate(2) return value as needed. */ 1510 if (error == ENOMEM) 1511 error = ENOSPC; 1512 return (error); 1513 } 1514 1515 static int 1516 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1517 { 1518 struct shm_mapping *shmm; 1519 struct sbuf sb; 1520 struct kinfo_file kif; 1521 u_long i; 1522 ssize_t curlen; 1523 int error, error2; 1524 1525 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1526 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1527 curlen = 0; 1528 error = 0; 1529 sx_slock(&shm_dict_lock); 1530 for (i = 0; i < shm_hash + 1; i++) { 1531 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1532 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1533 &kif, true); 1534 if (error == EPERM) 1535 continue; 1536 if (error != 0) 1537 break; 1538 pack_kinfo(&kif); 1539 if (req->oldptr != NULL && 1540 kif.kf_structsize + curlen > req->oldlen) 1541 break; 1542 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1543 0 : ENOMEM; 1544 if (error != 0) 1545 break; 1546 curlen += kif.kf_structsize; 1547 } 1548 } 1549 sx_sunlock(&shm_dict_lock); 1550 error2 = sbuf_finish(&sb); 1551 sbuf_delete(&sb); 1552 return (error != 0 ? error : error2); 1553 } 1554 1555 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1556 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1557 NULL, 0, sysctl_posix_shm_list, "", 1558 "POSIX SHM list"); 1559 1560 int 1561 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1562 struct filecaps *caps) 1563 { 1564 1565 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1566 } 1567 1568 /* 1569 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1570 * caller, and libc will enforce it for the traditional shm_open() call. This 1571 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1572 * interface also includes a 'name' argument that is currently unused, but could 1573 * potentially be exported later via some interface for debugging purposes. 1574 * From the kernel's perspective, it is optional. Individual consumers like 1575 * memfd_create() may require it in order to be compatible with other systems 1576 * implementing the same function. 1577 */ 1578 int 1579 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1580 { 1581 1582 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1583 uap->shmflags, NULL, uap->name)); 1584 } 1585