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_grab(object, idx, VM_ALLOC_NOCREAT); 461 if (m != NULL) { 462 MPASS(vm_page_all_valid(m)); 463 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 464 m = vm_page_alloc(object, idx, 465 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 466 if (m == NULL) 467 goto retry; 468 rv = vm_pager_get_pages(object, &m, 1, NULL, 469 NULL); 470 if (rv == VM_PAGER_OK) { 471 /* 472 * Since the page was not resident, 473 * and therefore not recently 474 * accessed, immediately enqueue it 475 * for asynchronous laundering. The 476 * current operation is not regarded 477 * as an access. 478 */ 479 vm_page_launder(m); 480 } else { 481 vm_page_free(m); 482 VM_OBJECT_WUNLOCK(object); 483 return (EIO); 484 } 485 } 486 if (m != NULL) { 487 pmap_zero_page_area(m, base, PAGE_SIZE - base); 488 KASSERT(vm_page_all_valid(m), 489 ("shm_dotruncate: page %p is invalid", m)); 490 vm_page_dirty(m); 491 vm_page_xunbusy(m); 492 vm_pager_page_unswapped(m); 493 } 494 } 495 delta = IDX_TO_OFF(object->size - nobjsize); 496 497 /* Toss in memory pages. */ 498 if (nobjsize < object->size) 499 vm_object_page_remove(object, nobjsize, object->size, 500 0); 501 502 /* Toss pages from swap. */ 503 if (object->type == OBJT_SWAP) 504 swap_pager_freespace(object, nobjsize, delta); 505 506 /* Free the swap accounted for shm */ 507 swap_release_by_cred(delta, object->cred); 508 object->charge -= delta; 509 } else { 510 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 511 return (EPERM); 512 513 /* Try to reserve additional swap space. */ 514 delta = IDX_TO_OFF(nobjsize - object->size); 515 if (!swap_reserve_by_cred(delta, object->cred)) 516 return (ENOMEM); 517 object->charge += delta; 518 } 519 shmfd->shm_size = length; 520 mtx_lock(&shm_timestamp_lock); 521 vfs_timestamp(&shmfd->shm_ctime); 522 shmfd->shm_mtime = shmfd->shm_ctime; 523 mtx_unlock(&shm_timestamp_lock); 524 object->size = nobjsize; 525 return (0); 526 } 527 528 int 529 shm_dotruncate(struct shmfd *shmfd, off_t length) 530 { 531 void *rl_cookie; 532 int error; 533 534 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 535 &shmfd->shm_mtx); 536 VM_OBJECT_WLOCK(shmfd->shm_object); 537 error = shm_dotruncate_locked(shmfd, length, rl_cookie); 538 VM_OBJECT_WUNLOCK(shmfd->shm_object); 539 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 540 return (error); 541 } 542 543 /* 544 * shmfd object management including creation and reference counting 545 * routines. 546 */ 547 struct shmfd * 548 shm_alloc(struct ucred *ucred, mode_t mode) 549 { 550 struct shmfd *shmfd; 551 552 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 553 shmfd->shm_size = 0; 554 shmfd->shm_uid = ucred->cr_uid; 555 shmfd->shm_gid = ucred->cr_gid; 556 shmfd->shm_mode = mode; 557 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 558 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 559 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 560 shmfd->shm_object->pg_color = 0; 561 VM_OBJECT_WLOCK(shmfd->shm_object); 562 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 563 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 564 VM_OBJECT_WUNLOCK(shmfd->shm_object); 565 vfs_timestamp(&shmfd->shm_birthtime); 566 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 567 shmfd->shm_birthtime; 568 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 569 refcount_init(&shmfd->shm_refs, 1); 570 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 571 rangelock_init(&shmfd->shm_rl); 572 #ifdef MAC 573 mac_posixshm_init(shmfd); 574 mac_posixshm_create(ucred, shmfd); 575 #endif 576 577 return (shmfd); 578 } 579 580 struct shmfd * 581 shm_hold(struct shmfd *shmfd) 582 { 583 584 refcount_acquire(&shmfd->shm_refs); 585 return (shmfd); 586 } 587 588 void 589 shm_drop(struct shmfd *shmfd) 590 { 591 592 if (refcount_release(&shmfd->shm_refs)) { 593 #ifdef MAC 594 mac_posixshm_destroy(shmfd); 595 #endif 596 rangelock_destroy(&shmfd->shm_rl); 597 mtx_destroy(&shmfd->shm_mtx); 598 vm_object_deallocate(shmfd->shm_object); 599 free(shmfd, M_SHMFD); 600 } 601 } 602 603 /* 604 * Determine if the credentials have sufficient permissions for a 605 * specified combination of FREAD and FWRITE. 606 */ 607 int 608 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 609 { 610 accmode_t accmode; 611 int error; 612 613 accmode = 0; 614 if (flags & FREAD) 615 accmode |= VREAD; 616 if (flags & FWRITE) 617 accmode |= VWRITE; 618 mtx_lock(&shm_timestamp_lock); 619 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 620 accmode, ucred, NULL); 621 mtx_unlock(&shm_timestamp_lock); 622 return (error); 623 } 624 625 /* 626 * Dictionary management. We maintain an in-kernel dictionary to map 627 * paths to shmfd objects. We use the FNV hash on the path to store 628 * the mappings in a hash table. 629 */ 630 static void 631 shm_init(void *arg) 632 { 633 634 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 635 sx_init(&shm_dict_lock, "shm dictionary"); 636 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 637 new_unrhdr64(&shm_ino_unr, 1); 638 shm_dev_ino = devfs_alloc_cdp_inode(); 639 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 640 } 641 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 642 643 static struct shmfd * 644 shm_lookup(char *path, Fnv32_t fnv) 645 { 646 struct shm_mapping *map; 647 648 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 649 if (map->sm_fnv != fnv) 650 continue; 651 if (strcmp(map->sm_path, path) == 0) 652 return (map->sm_shmfd); 653 } 654 655 return (NULL); 656 } 657 658 static void 659 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 660 { 661 struct shm_mapping *map; 662 663 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 664 map->sm_path = path; 665 map->sm_fnv = fnv; 666 map->sm_shmfd = shm_hold(shmfd); 667 shmfd->shm_path = path; 668 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 669 } 670 671 static int 672 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 673 { 674 struct shm_mapping *map; 675 int error; 676 677 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 678 if (map->sm_fnv != fnv) 679 continue; 680 if (strcmp(map->sm_path, path) == 0) { 681 #ifdef MAC 682 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 683 if (error) 684 return (error); 685 #endif 686 error = shm_access(map->sm_shmfd, ucred, 687 FREAD | FWRITE); 688 if (error) 689 return (error); 690 map->sm_shmfd->shm_path = NULL; 691 LIST_REMOVE(map, sm_link); 692 shm_drop(map->sm_shmfd); 693 free(map->sm_path, M_SHMFD); 694 free(map, M_SHMFD); 695 return (0); 696 } 697 } 698 699 return (ENOENT); 700 } 701 702 int 703 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 704 struct filecaps *fcaps, int initial_seals) 705 { 706 struct filedesc *fdp; 707 struct shmfd *shmfd; 708 struct file *fp; 709 char *path; 710 const char *pr_path; 711 void *rl_cookie; 712 size_t pr_pathlen; 713 Fnv32_t fnv; 714 mode_t cmode; 715 int fd, error; 716 717 #ifdef CAPABILITY_MODE 718 /* 719 * shm_open(2) is only allowed for anonymous objects. 720 */ 721 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 722 return (ECAPMODE); 723 #endif 724 725 AUDIT_ARG_FFLAGS(flags); 726 AUDIT_ARG_MODE(mode); 727 728 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 729 return (EINVAL); 730 731 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 732 return (EINVAL); 733 734 /* 735 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 736 * If the decision is made later to allow additional seals, care must be 737 * taken below to ensure that the seals are properly set if the shmfd 738 * already existed -- this currently assumes that only F_SEAL_SEAL can 739 * be set and doesn't take further precautions to ensure the validity of 740 * the seals being added with respect to current mappings. 741 */ 742 if ((initial_seals & ~F_SEAL_SEAL) != 0) 743 return (EINVAL); 744 745 fdp = td->td_proc->p_fd; 746 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 747 748 /* 749 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 750 * by POSIX. We allow it to be unset here so that an in-kernel 751 * interface may be written as a thin layer around shm, optionally not 752 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 753 * in sys_shm_open() to keep this implementation compliant. 754 */ 755 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 756 if (error) 757 return (error); 758 759 /* A SHM_ANON path pointer creates an anonymous object. */ 760 if (userpath == SHM_ANON) { 761 /* A read-only anonymous object is pointless. */ 762 if ((flags & O_ACCMODE) == O_RDONLY) { 763 fdclose(td, fp, fd); 764 fdrop(fp, td); 765 return (EINVAL); 766 } 767 shmfd = shm_alloc(td->td_ucred, cmode); 768 shmfd->shm_seals = initial_seals; 769 } else { 770 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 771 pr_path = td->td_ucred->cr_prison->pr_path; 772 773 /* Construct a full pathname for jailed callers. */ 774 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 775 : strlcpy(path, pr_path, MAXPATHLEN); 776 error = copyinstr(userpath, path + pr_pathlen, 777 MAXPATHLEN - pr_pathlen, NULL); 778 #ifdef KTRACE 779 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 780 ktrnamei(path); 781 #endif 782 /* Require paths to start with a '/' character. */ 783 if (error == 0 && path[pr_pathlen] != '/') 784 error = EINVAL; 785 if (error) { 786 fdclose(td, fp, fd); 787 fdrop(fp, td); 788 free(path, M_SHMFD); 789 return (error); 790 } 791 792 AUDIT_ARG_UPATH1_CANON(path); 793 fnv = fnv_32_str(path, FNV1_32_INIT); 794 sx_xlock(&shm_dict_lock); 795 shmfd = shm_lookup(path, fnv); 796 if (shmfd == NULL) { 797 /* Object does not yet exist, create it if requested. */ 798 if (flags & O_CREAT) { 799 #ifdef MAC 800 error = mac_posixshm_check_create(td->td_ucred, 801 path); 802 if (error == 0) { 803 #endif 804 shmfd = shm_alloc(td->td_ucred, cmode); 805 shmfd->shm_seals = initial_seals; 806 shm_insert(path, fnv, shmfd); 807 #ifdef MAC 808 } 809 #endif 810 } else { 811 free(path, M_SHMFD); 812 error = ENOENT; 813 } 814 } else { 815 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 816 &shmfd->shm_mtx); 817 818 /* 819 * kern_shm_open() likely shouldn't ever error out on 820 * trying to set a seal that already exists, unlike 821 * F_ADD_SEALS. This would break terribly as 822 * shm_open(2) actually sets F_SEAL_SEAL to maintain 823 * historical behavior where the underlying file could 824 * not be sealed. 825 */ 826 initial_seals &= ~shmfd->shm_seals; 827 828 /* 829 * Object already exists, obtain a new 830 * reference if requested and permitted. 831 */ 832 free(path, M_SHMFD); 833 834 /* 835 * initial_seals can't set additional seals if we've 836 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 837 * then we've already removed that one from 838 * initial_seals. This is currently redundant as we 839 * only allow setting F_SEAL_SEAL at creation time, but 840 * it's cheap to check and decreases the effort required 841 * to allow additional seals. 842 */ 843 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 844 initial_seals != 0) 845 error = EPERM; 846 else if ((flags & (O_CREAT | O_EXCL)) == 847 (O_CREAT | O_EXCL)) 848 error = EEXIST; 849 else { 850 #ifdef MAC 851 error = mac_posixshm_check_open(td->td_ucred, 852 shmfd, FFLAGS(flags & O_ACCMODE)); 853 if (error == 0) 854 #endif 855 error = shm_access(shmfd, td->td_ucred, 856 FFLAGS(flags & O_ACCMODE)); 857 } 858 859 /* 860 * Truncate the file back to zero length if 861 * O_TRUNC was specified and the object was 862 * opened with read/write. 863 */ 864 if (error == 0 && 865 (flags & (O_ACCMODE | O_TRUNC)) == 866 (O_RDWR | O_TRUNC)) { 867 VM_OBJECT_WLOCK(shmfd->shm_object); 868 #ifdef MAC 869 error = mac_posixshm_check_truncate( 870 td->td_ucred, fp->f_cred, shmfd); 871 if (error == 0) 872 #endif 873 error = shm_dotruncate_locked(shmfd, 0, 874 rl_cookie); 875 VM_OBJECT_WUNLOCK(shmfd->shm_object); 876 } 877 if (error == 0) { 878 /* 879 * Currently we only allow F_SEAL_SEAL to be 880 * set initially. As noted above, this would 881 * need to be reworked should that change. 882 */ 883 shmfd->shm_seals |= initial_seals; 884 shm_hold(shmfd); 885 } 886 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 887 &shmfd->shm_mtx); 888 } 889 sx_xunlock(&shm_dict_lock); 890 891 if (error) { 892 fdclose(td, fp, fd); 893 fdrop(fp, td); 894 return (error); 895 } 896 } 897 898 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 899 900 td->td_retval[0] = fd; 901 fdrop(fp, td); 902 903 return (0); 904 } 905 906 /* System calls. */ 907 #ifdef COMPAT_FREEBSD12 908 int 909 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 910 { 911 912 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode, 913 NULL, F_SEAL_SEAL)); 914 } 915 #endif 916 917 int 918 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 919 { 920 char *path; 921 const char *pr_path; 922 size_t pr_pathlen; 923 Fnv32_t fnv; 924 int error; 925 926 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 927 pr_path = td->td_ucred->cr_prison->pr_path; 928 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 929 : strlcpy(path, pr_path, MAXPATHLEN); 930 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 931 NULL); 932 if (error) { 933 free(path, M_TEMP); 934 return (error); 935 } 936 #ifdef KTRACE 937 if (KTRPOINT(curthread, KTR_NAMEI)) 938 ktrnamei(path); 939 #endif 940 AUDIT_ARG_UPATH1_CANON(path); 941 fnv = fnv_32_str(path, FNV1_32_INIT); 942 sx_xlock(&shm_dict_lock); 943 error = shm_remove(path, fnv, td->td_ucred); 944 sx_xunlock(&shm_dict_lock); 945 free(path, M_TEMP); 946 947 return (error); 948 } 949 950 int 951 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 952 { 953 char *path_from = NULL, *path_to = NULL; 954 Fnv32_t fnv_from, fnv_to; 955 struct shmfd *fd_from; 956 struct shmfd *fd_to; 957 int error; 958 int flags; 959 960 flags = uap->flags; 961 962 /* 963 * Make sure the user passed only valid flags. 964 * If you add a new flag, please add a new term here. 965 */ 966 if ((flags & ~( 967 SHM_RENAME_NOREPLACE | 968 SHM_RENAME_EXCHANGE 969 )) != 0) { 970 error = EINVAL; 971 goto out; 972 } 973 974 /* 975 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 976 * force the user to choose one or the other. 977 */ 978 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 979 (flags & SHM_RENAME_EXCHANGE) != 0) { 980 error = EINVAL; 981 goto out; 982 } 983 984 /* 985 * Malloc zone M_SHMFD, since this path may end up freed later from 986 * M_SHMFD if we end up doing an insert. 987 */ 988 path_from = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 989 error = copyinstr(uap->path_from, path_from, MAXPATHLEN, NULL); 990 if (error) 991 goto out; 992 993 path_to = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 994 error = copyinstr(uap->path_to, path_to, MAXPATHLEN, NULL); 995 if (error) 996 goto out; 997 998 /* Rename with from/to equal is a no-op */ 999 if (strncmp(path_from, path_to, MAXPATHLEN) == 0) 1000 goto out; 1001 1002 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1003 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1004 1005 sx_xlock(&shm_dict_lock); 1006 1007 fd_from = shm_lookup(path_from, fnv_from); 1008 if (fd_from == NULL) { 1009 sx_xunlock(&shm_dict_lock); 1010 error = ENOENT; 1011 goto out; 1012 } 1013 1014 fd_to = shm_lookup(path_to, fnv_to); 1015 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1016 sx_xunlock(&shm_dict_lock); 1017 error = EEXIST; 1018 goto out; 1019 } 1020 1021 /* 1022 * Unconditionally prevents shm_remove from invalidating the 'from' 1023 * shm's state. 1024 */ 1025 shm_hold(fd_from); 1026 error = shm_remove(path_from, fnv_from, td->td_ucred); 1027 1028 /* 1029 * One of my assumptions failed if ENOENT (e.g. locking didn't 1030 * protect us) 1031 */ 1032 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1033 path_from)); 1034 if (error) { 1035 shm_drop(fd_from); 1036 sx_xunlock(&shm_dict_lock); 1037 goto out; 1038 } 1039 1040 /* 1041 * If we are exchanging, we need to ensure the shm_remove below 1042 * doesn't invalidate the dest shm's state. 1043 */ 1044 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1045 shm_hold(fd_to); 1046 1047 /* 1048 * NOTE: if path_to is not already in the hash, c'est la vie; 1049 * it simply means we have nothing already at path_to to unlink. 1050 * That is the ENOENT case. 1051 * 1052 * If we somehow don't have access to unlink this guy, but 1053 * did for the shm at path_from, then relink the shm to path_from 1054 * and abort with EACCES. 1055 * 1056 * All other errors: that is weird; let's relink and abort the 1057 * operation. 1058 */ 1059 error = shm_remove(path_to, fnv_to, td->td_ucred); 1060 if (error && error != ENOENT) { 1061 shm_insert(path_from, fnv_from, fd_from); 1062 shm_drop(fd_from); 1063 /* Don't free path_from now, since the hash references it */ 1064 path_from = NULL; 1065 sx_xunlock(&shm_dict_lock); 1066 goto out; 1067 } 1068 1069 shm_insert(path_to, fnv_to, fd_from); 1070 1071 /* Don't free path_to now, since the hash references it */ 1072 path_to = NULL; 1073 1074 /* We kept a ref when we removed, and incremented again in insert */ 1075 shm_drop(fd_from); 1076 #ifdef DEBUG 1077 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1078 fd_from->shm_refs)); 1079 #endif 1080 1081 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1082 shm_insert(path_from, fnv_from, fd_to); 1083 path_from = NULL; 1084 shm_drop(fd_to); 1085 #ifdef DEBUG 1086 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1087 fd_to->shm_refs)); 1088 #endif 1089 } 1090 1091 error = 0; 1092 sx_xunlock(&shm_dict_lock); 1093 1094 out: 1095 if (path_from != NULL) 1096 free(path_from, M_SHMFD); 1097 if (path_to != NULL) 1098 free(path_to, M_SHMFD); 1099 return(error); 1100 } 1101 1102 int 1103 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1104 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1105 vm_ooffset_t foff, struct thread *td) 1106 { 1107 struct shmfd *shmfd; 1108 vm_prot_t maxprot; 1109 int error; 1110 bool writecnt; 1111 void *rl_cookie; 1112 1113 shmfd = fp->f_data; 1114 maxprot = VM_PROT_NONE; 1115 1116 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1117 &shmfd->shm_mtx); 1118 /* FREAD should always be set. */ 1119 if ((fp->f_flag & FREAD) != 0) 1120 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1121 if ((fp->f_flag & FWRITE) != 0) 1122 maxprot |= VM_PROT_WRITE; 1123 1124 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; 1125 1126 if (writecnt && (shmfd->shm_seals & F_SEAL_WRITE) != 0) { 1127 error = EPERM; 1128 goto out; 1129 } 1130 1131 /* Don't permit shared writable mappings on read-only descriptors. */ 1132 if (writecnt && (maxprot & VM_PROT_WRITE) == 0) { 1133 error = EACCES; 1134 goto out; 1135 } 1136 maxprot &= cap_maxprot; 1137 1138 /* See comment in vn_mmap(). */ 1139 if ( 1140 #ifdef _LP64 1141 objsize > OFF_MAX || 1142 #endif 1143 foff < 0 || foff > OFF_MAX - objsize) { 1144 error = EINVAL; 1145 goto out; 1146 } 1147 1148 #ifdef MAC 1149 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1150 if (error != 0) 1151 goto out; 1152 #endif 1153 1154 mtx_lock(&shm_timestamp_lock); 1155 vfs_timestamp(&shmfd->shm_atime); 1156 mtx_unlock(&shm_timestamp_lock); 1157 vm_object_reference(shmfd->shm_object); 1158 1159 if (writecnt) 1160 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 1161 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1162 shmfd->shm_object, foff, writecnt, td); 1163 if (error != 0) { 1164 if (writecnt) 1165 vm_pager_release_writecount(shmfd->shm_object, 0, 1166 objsize); 1167 vm_object_deallocate(shmfd->shm_object); 1168 } 1169 out: 1170 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1171 return (error); 1172 } 1173 1174 static int 1175 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1176 struct thread *td) 1177 { 1178 struct shmfd *shmfd; 1179 int error; 1180 1181 error = 0; 1182 shmfd = fp->f_data; 1183 mtx_lock(&shm_timestamp_lock); 1184 /* 1185 * SUSv4 says that x bits of permission need not be affected. 1186 * Be consistent with our shm_open there. 1187 */ 1188 #ifdef MAC 1189 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1190 if (error != 0) 1191 goto out; 1192 #endif 1193 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 1194 shmfd->shm_gid, VADMIN, active_cred, NULL); 1195 if (error != 0) 1196 goto out; 1197 shmfd->shm_mode = mode & ACCESSPERMS; 1198 out: 1199 mtx_unlock(&shm_timestamp_lock); 1200 return (error); 1201 } 1202 1203 static int 1204 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1205 struct thread *td) 1206 { 1207 struct shmfd *shmfd; 1208 int error; 1209 1210 error = 0; 1211 shmfd = fp->f_data; 1212 mtx_lock(&shm_timestamp_lock); 1213 #ifdef MAC 1214 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1215 if (error != 0) 1216 goto out; 1217 #endif 1218 if (uid == (uid_t)-1) 1219 uid = shmfd->shm_uid; 1220 if (gid == (gid_t)-1) 1221 gid = shmfd->shm_gid; 1222 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1223 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1224 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1225 goto out; 1226 shmfd->shm_uid = uid; 1227 shmfd->shm_gid = gid; 1228 out: 1229 mtx_unlock(&shm_timestamp_lock); 1230 return (error); 1231 } 1232 1233 /* 1234 * Helper routines to allow the backing object of a shared memory file 1235 * descriptor to be mapped in the kernel. 1236 */ 1237 int 1238 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1239 { 1240 struct shmfd *shmfd; 1241 vm_offset_t kva, ofs; 1242 vm_object_t obj; 1243 int rv; 1244 1245 if (fp->f_type != DTYPE_SHM) 1246 return (EINVAL); 1247 shmfd = fp->f_data; 1248 obj = shmfd->shm_object; 1249 VM_OBJECT_WLOCK(obj); 1250 /* 1251 * XXXRW: This validation is probably insufficient, and subject to 1252 * sign errors. It should be fixed. 1253 */ 1254 if (offset >= shmfd->shm_size || 1255 offset + size > round_page(shmfd->shm_size)) { 1256 VM_OBJECT_WUNLOCK(obj); 1257 return (EINVAL); 1258 } 1259 1260 shmfd->shm_kmappings++; 1261 vm_object_reference_locked(obj); 1262 VM_OBJECT_WUNLOCK(obj); 1263 1264 /* Map the object into the kernel_map and wire it. */ 1265 kva = vm_map_min(kernel_map); 1266 ofs = offset & PAGE_MASK; 1267 offset = trunc_page(offset); 1268 size = round_page(size + ofs); 1269 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1270 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1271 VM_PROT_READ | VM_PROT_WRITE, 0); 1272 if (rv == KERN_SUCCESS) { 1273 rv = vm_map_wire(kernel_map, kva, kva + size, 1274 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1275 if (rv == KERN_SUCCESS) { 1276 *memp = (void *)(kva + ofs); 1277 return (0); 1278 } 1279 vm_map_remove(kernel_map, kva, kva + size); 1280 } else 1281 vm_object_deallocate(obj); 1282 1283 /* On failure, drop our mapping reference. */ 1284 VM_OBJECT_WLOCK(obj); 1285 shmfd->shm_kmappings--; 1286 VM_OBJECT_WUNLOCK(obj); 1287 1288 return (vm_mmap_to_errno(rv)); 1289 } 1290 1291 /* 1292 * We require the caller to unmap the entire entry. This allows us to 1293 * safely decrement shm_kmappings when a mapping is removed. 1294 */ 1295 int 1296 shm_unmap(struct file *fp, void *mem, size_t size) 1297 { 1298 struct shmfd *shmfd; 1299 vm_map_entry_t entry; 1300 vm_offset_t kva, ofs; 1301 vm_object_t obj; 1302 vm_pindex_t pindex; 1303 vm_prot_t prot; 1304 boolean_t wired; 1305 vm_map_t map; 1306 int rv; 1307 1308 if (fp->f_type != DTYPE_SHM) 1309 return (EINVAL); 1310 shmfd = fp->f_data; 1311 kva = (vm_offset_t)mem; 1312 ofs = kva & PAGE_MASK; 1313 kva = trunc_page(kva); 1314 size = round_page(size + ofs); 1315 map = kernel_map; 1316 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1317 &obj, &pindex, &prot, &wired); 1318 if (rv != KERN_SUCCESS) 1319 return (EINVAL); 1320 if (entry->start != kva || entry->end != kva + size) { 1321 vm_map_lookup_done(map, entry); 1322 return (EINVAL); 1323 } 1324 vm_map_lookup_done(map, entry); 1325 if (obj != shmfd->shm_object) 1326 return (EINVAL); 1327 vm_map_remove(map, kva, kva + size); 1328 VM_OBJECT_WLOCK(obj); 1329 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1330 shmfd->shm_kmappings--; 1331 VM_OBJECT_WUNLOCK(obj); 1332 return (0); 1333 } 1334 1335 static int 1336 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1337 { 1338 const char *path, *pr_path; 1339 size_t pr_pathlen; 1340 bool visible; 1341 1342 sx_assert(&shm_dict_lock, SA_LOCKED); 1343 kif->kf_type = KF_TYPE_SHM; 1344 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1345 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1346 if (shmfd->shm_path != NULL) { 1347 if (shmfd->shm_path != NULL) { 1348 path = shmfd->shm_path; 1349 pr_path = curthread->td_ucred->cr_prison->pr_path; 1350 if (strcmp(pr_path, "/") != 0) { 1351 /* Return the jail-rooted pathname. */ 1352 pr_pathlen = strlen(pr_path); 1353 visible = strncmp(path, pr_path, pr_pathlen) 1354 == 0 && path[pr_pathlen] == '/'; 1355 if (list && !visible) 1356 return (EPERM); 1357 if (visible) 1358 path += pr_pathlen; 1359 } 1360 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1361 } 1362 } 1363 return (0); 1364 } 1365 1366 static int 1367 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1368 struct filedesc *fdp __unused) 1369 { 1370 int res; 1371 1372 sx_slock(&shm_dict_lock); 1373 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1374 sx_sunlock(&shm_dict_lock); 1375 return (res); 1376 } 1377 1378 static int 1379 shm_add_seals(struct file *fp, int seals) 1380 { 1381 struct shmfd *shmfd; 1382 void *rl_cookie; 1383 vm_ooffset_t writemappings; 1384 int error, nseals; 1385 1386 error = 0; 1387 shmfd = fp->f_data; 1388 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1389 &shmfd->shm_mtx); 1390 1391 /* Even already-set seals should result in EPERM. */ 1392 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1393 error = EPERM; 1394 goto out; 1395 } 1396 nseals = seals & ~shmfd->shm_seals; 1397 if ((nseals & F_SEAL_WRITE) != 0) { 1398 /* 1399 * The rangelock above prevents writable mappings from being 1400 * added after we've started applying seals. The RLOCK here 1401 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1402 * writemappings will be done without a rangelock. 1403 */ 1404 VM_OBJECT_RLOCK(shmfd->shm_object); 1405 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1406 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1407 /* kmappings are also writable */ 1408 if (writemappings > 0) { 1409 error = EBUSY; 1410 goto out; 1411 } 1412 } 1413 shmfd->shm_seals |= nseals; 1414 out: 1415 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1416 return (error); 1417 } 1418 1419 static int 1420 shm_get_seals(struct file *fp, int *seals) 1421 { 1422 struct shmfd *shmfd; 1423 1424 shmfd = fp->f_data; 1425 *seals = shmfd->shm_seals; 1426 return (0); 1427 } 1428 1429 static int 1430 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1431 { 1432 struct shm_mapping *shmm; 1433 struct sbuf sb; 1434 struct kinfo_file kif; 1435 u_long i; 1436 ssize_t curlen; 1437 int error, error2; 1438 1439 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1440 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1441 curlen = 0; 1442 error = 0; 1443 sx_slock(&shm_dict_lock); 1444 for (i = 0; i < shm_hash + 1; i++) { 1445 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1446 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1447 &kif, true); 1448 if (error == EPERM) 1449 continue; 1450 if (error != 0) 1451 break; 1452 pack_kinfo(&kif); 1453 if (req->oldptr != NULL && 1454 kif.kf_structsize + curlen > req->oldlen) 1455 break; 1456 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1457 0 : ENOMEM; 1458 if (error != 0) 1459 break; 1460 curlen += kif.kf_structsize; 1461 } 1462 } 1463 sx_sunlock(&shm_dict_lock); 1464 error2 = sbuf_finish(&sb); 1465 sbuf_delete(&sb); 1466 return (error != 0 ? error : error2); 1467 } 1468 1469 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1470 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1471 NULL, 0, sysctl_posix_shm_list, "", 1472 "POSIX SHM list"); 1473 1474 int 1475 kern_shm_open2(struct thread *td, const char *path, int flags, mode_t mode, 1476 int shmflags, const char *name __unused) 1477 { 1478 int initial_seals; 1479 1480 if ((shmflags & ~SHM_ALLOW_SEALING) != 0) 1481 return (EINVAL); 1482 1483 initial_seals = F_SEAL_SEAL; 1484 if ((shmflags & SHM_ALLOW_SEALING) != 0) 1485 initial_seals &= ~F_SEAL_SEAL; 1486 return (kern_shm_open(td, path, flags, mode, NULL, initial_seals)); 1487 } 1488 1489 /* 1490 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1491 * caller, and libc will enforce it for the traditional shm_open() call. This 1492 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1493 * interface also includes a 'name' argument that is currently unused, but could 1494 * potentially be exported later via some interface for debugging purposes. 1495 * From the kernel's perspective, it is optional. Individual consumers like 1496 * memfd_create() may require it in order to be compatible with other systems 1497 * implementing the same function. 1498 */ 1499 int 1500 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1501 { 1502 1503 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1504 uap->shmflags, uap->name)); 1505 } 1506