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