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) and shm_unlink(2). While most of the implementation is 37 * here, vm_mmap.c contains mapping logic changes. 38 * 39 * posixshmcontrol(1) allows users to inspect the state of the memory 40 * objects. Per-uid swap resource limit controls total amount of 41 * memory that user can consume for anonymous objects, including 42 * shared. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include "opt_capsicum.h" 49 #include "opt_ktrace.h" 50 51 #include <sys/param.h> 52 #include <sys/capsicum.h> 53 #include <sys/conf.h> 54 #include <sys/fcntl.h> 55 #include <sys/file.h> 56 #include <sys/filedesc.h> 57 #include <sys/filio.h> 58 #include <sys/fnv_hash.h> 59 #include <sys/kernel.h> 60 #include <sys/uio.h> 61 #include <sys/signal.h> 62 #include <sys/jail.h> 63 #include <sys/ktrace.h> 64 #include <sys/lock.h> 65 #include <sys/malloc.h> 66 #include <sys/mman.h> 67 #include <sys/mutex.h> 68 #include <sys/priv.h> 69 #include <sys/proc.h> 70 #include <sys/refcount.h> 71 #include <sys/resourcevar.h> 72 #include <sys/rwlock.h> 73 #include <sys/sbuf.h> 74 #include <sys/stat.h> 75 #include <sys/syscallsubr.h> 76 #include <sys/sysctl.h> 77 #include <sys/sysproto.h> 78 #include <sys/systm.h> 79 #include <sys/sx.h> 80 #include <sys/time.h> 81 #include <sys/vnode.h> 82 #include <sys/unistd.h> 83 #include <sys/user.h> 84 85 #include <security/audit/audit.h> 86 #include <security/mac/mac_framework.h> 87 88 #include <vm/vm.h> 89 #include <vm/vm_param.h> 90 #include <vm/pmap.h> 91 #include <vm/vm_extern.h> 92 #include <vm/vm_map.h> 93 #include <vm/vm_kern.h> 94 #include <vm/vm_object.h> 95 #include <vm/vm_page.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_pager.h> 98 #include <vm/swap_pager.h> 99 100 struct shm_mapping { 101 char *sm_path; 102 Fnv32_t sm_fnv; 103 struct shmfd *sm_shmfd; 104 LIST_ENTRY(shm_mapping) sm_link; 105 }; 106 107 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 108 static LIST_HEAD(, shm_mapping) *shm_dictionary; 109 static struct sx shm_dict_lock; 110 static struct mtx shm_timestamp_lock; 111 static u_long shm_hash; 112 static struct unrhdr64 shm_ino_unr; 113 static dev_t shm_dev_ino; 114 115 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 116 117 static void shm_init(void *arg); 118 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 119 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 120 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 121 122 static fo_rdwr_t shm_read; 123 static fo_rdwr_t shm_write; 124 static fo_truncate_t shm_truncate; 125 static fo_ioctl_t shm_ioctl; 126 static fo_stat_t shm_stat; 127 static fo_close_t shm_close; 128 static fo_chmod_t shm_chmod; 129 static fo_chown_t shm_chown; 130 static fo_seek_t shm_seek; 131 static fo_fill_kinfo_t shm_fill_kinfo; 132 static fo_mmap_t shm_mmap; 133 134 /* File descriptor operations. */ 135 struct fileops shm_ops = { 136 .fo_read = shm_read, 137 .fo_write = shm_write, 138 .fo_truncate = shm_truncate, 139 .fo_ioctl = shm_ioctl, 140 .fo_poll = invfo_poll, 141 .fo_kqfilter = invfo_kqfilter, 142 .fo_stat = shm_stat, 143 .fo_close = shm_close, 144 .fo_chmod = shm_chmod, 145 .fo_chown = shm_chown, 146 .fo_sendfile = vn_sendfile, 147 .fo_seek = shm_seek, 148 .fo_fill_kinfo = shm_fill_kinfo, 149 .fo_mmap = shm_mmap, 150 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 151 }; 152 153 FEATURE(posix_shm, "POSIX shared memory"); 154 155 static int 156 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 157 { 158 vm_page_t m; 159 vm_pindex_t idx; 160 size_t tlen; 161 int error, offset, rv; 162 163 idx = OFF_TO_IDX(uio->uio_offset); 164 offset = uio->uio_offset & PAGE_MASK; 165 tlen = MIN(PAGE_SIZE - offset, len); 166 167 VM_OBJECT_WLOCK(obj); 168 169 /* 170 * Read I/O without either a corresponding resident page or swap 171 * page: use zero_region. This is intended to avoid instantiating 172 * pages on read from a sparse region. 173 */ 174 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 175 !vm_pager_has_page(obj, idx, NULL, NULL)) { 176 VM_OBJECT_WUNLOCK(obj); 177 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 178 } 179 180 /* 181 * Parallel reads of the page content from disk are prevented 182 * by exclusive busy. 183 * 184 * Although the tmpfs vnode lock is held here, it is 185 * nonetheless safe to sleep waiting for a free page. The 186 * pageout daemon does not need to acquire the tmpfs vnode 187 * lock to page out tobj's pages because tobj is a OBJT_SWAP 188 * type object. 189 */ 190 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 191 if (m->valid != VM_PAGE_BITS_ALL) { 192 vm_page_xbusy(m); 193 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 194 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL); 195 if (rv != VM_PAGER_OK) { 196 printf( 197 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 198 obj, idx, m->valid, rv); 199 vm_page_lock(m); 200 vm_page_free(m); 201 vm_page_unlock(m); 202 VM_OBJECT_WUNLOCK(obj); 203 return (EIO); 204 } 205 } else 206 vm_page_zero_invalid(m, TRUE); 207 vm_page_xunbusy(m); 208 } 209 vm_page_lock(m); 210 vm_page_hold(m); 211 if (vm_page_active(m)) 212 vm_page_reference(m); 213 else 214 vm_page_activate(m); 215 vm_page_unlock(m); 216 VM_OBJECT_WUNLOCK(obj); 217 error = uiomove_fromphys(&m, offset, tlen, uio); 218 if (uio->uio_rw == UIO_WRITE && error == 0) { 219 VM_OBJECT_WLOCK(obj); 220 vm_page_dirty(m); 221 vm_pager_page_unswapped(m); 222 VM_OBJECT_WUNLOCK(obj); 223 } 224 vm_page_lock(m); 225 vm_page_unhold(m); 226 vm_page_unlock(m); 227 228 return (error); 229 } 230 231 int 232 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 233 { 234 ssize_t resid; 235 size_t len; 236 int error; 237 238 error = 0; 239 while ((resid = uio->uio_resid) > 0) { 240 if (obj_size <= uio->uio_offset) 241 break; 242 len = MIN(obj_size - uio->uio_offset, resid); 243 if (len == 0) 244 break; 245 error = uiomove_object_page(obj, len, uio); 246 if (error != 0 || resid == uio->uio_resid) 247 break; 248 } 249 return (error); 250 } 251 252 static int 253 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 254 { 255 struct shmfd *shmfd; 256 off_t foffset; 257 int error; 258 259 shmfd = fp->f_data; 260 foffset = foffset_lock(fp, 0); 261 error = 0; 262 switch (whence) { 263 case L_INCR: 264 if (foffset < 0 || 265 (offset > 0 && foffset > OFF_MAX - offset)) { 266 error = EOVERFLOW; 267 break; 268 } 269 offset += foffset; 270 break; 271 case L_XTND: 272 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 273 error = EOVERFLOW; 274 break; 275 } 276 offset += shmfd->shm_size; 277 break; 278 case L_SET: 279 break; 280 default: 281 error = EINVAL; 282 } 283 if (error == 0) { 284 if (offset < 0 || offset > shmfd->shm_size) 285 error = EINVAL; 286 else 287 td->td_uretoff.tdu_off = offset; 288 } 289 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 290 return (error); 291 } 292 293 static int 294 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 295 int flags, struct thread *td) 296 { 297 struct shmfd *shmfd; 298 void *rl_cookie; 299 int error; 300 301 shmfd = fp->f_data; 302 #ifdef MAC 303 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 304 if (error) 305 return (error); 306 #endif 307 foffset_lock_uio(fp, uio, flags); 308 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 309 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 310 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 311 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 312 foffset_unlock_uio(fp, uio, flags); 313 return (error); 314 } 315 316 static int 317 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 318 int flags, struct thread *td) 319 { 320 struct shmfd *shmfd; 321 void *rl_cookie; 322 int error; 323 324 shmfd = fp->f_data; 325 #ifdef MAC 326 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 327 if (error) 328 return (error); 329 #endif 330 foffset_lock_uio(fp, uio, flags); 331 if ((flags & FOF_OFFSET) == 0) { 332 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 333 &shmfd->shm_mtx); 334 } else { 335 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 336 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 337 } 338 339 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 340 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 341 foffset_unlock_uio(fp, uio, flags); 342 return (error); 343 } 344 345 static int 346 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 347 struct thread *td) 348 { 349 struct shmfd *shmfd; 350 #ifdef MAC 351 int error; 352 #endif 353 354 shmfd = fp->f_data; 355 #ifdef MAC 356 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 357 if (error) 358 return (error); 359 #endif 360 return (shm_dotruncate(shmfd, length)); 361 } 362 363 int 364 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 365 struct thread *td) 366 { 367 368 switch (com) { 369 case FIONBIO: 370 case FIOASYNC: 371 /* 372 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 373 * just like it would on an unlinked regular file 374 */ 375 return (0); 376 default: 377 return (ENOTTY); 378 } 379 } 380 381 static int 382 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 383 struct thread *td) 384 { 385 struct shmfd *shmfd; 386 #ifdef MAC 387 int error; 388 #endif 389 390 shmfd = fp->f_data; 391 392 #ifdef MAC 393 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 394 if (error) 395 return (error); 396 #endif 397 398 /* 399 * Attempt to return sanish values for fstat() on a memory file 400 * descriptor. 401 */ 402 bzero(sb, sizeof(*sb)); 403 sb->st_blksize = PAGE_SIZE; 404 sb->st_size = shmfd->shm_size; 405 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 406 mtx_lock(&shm_timestamp_lock); 407 sb->st_atim = shmfd->shm_atime; 408 sb->st_ctim = shmfd->shm_ctime; 409 sb->st_mtim = shmfd->shm_mtime; 410 sb->st_birthtim = shmfd->shm_birthtime; 411 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 412 sb->st_uid = shmfd->shm_uid; 413 sb->st_gid = shmfd->shm_gid; 414 mtx_unlock(&shm_timestamp_lock); 415 sb->st_dev = shm_dev_ino; 416 sb->st_ino = shmfd->shm_ino; 417 sb->st_nlink = shmfd->shm_object->ref_count; 418 419 return (0); 420 } 421 422 static int 423 shm_close(struct file *fp, struct thread *td) 424 { 425 struct shmfd *shmfd; 426 427 shmfd = fp->f_data; 428 fp->f_data = NULL; 429 shm_drop(shmfd); 430 431 return (0); 432 } 433 434 int 435 shm_dotruncate(struct shmfd *shmfd, off_t length) 436 { 437 vm_object_t object; 438 vm_page_t m; 439 vm_pindex_t idx, nobjsize; 440 vm_ooffset_t delta; 441 int base, rv; 442 443 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 444 object = shmfd->shm_object; 445 VM_OBJECT_WLOCK(object); 446 if (length == shmfd->shm_size) { 447 VM_OBJECT_WUNLOCK(object); 448 return (0); 449 } 450 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 451 452 /* Are we shrinking? If so, trim the end. */ 453 if (length < shmfd->shm_size) { 454 /* 455 * Disallow any requests to shrink the size if this 456 * object is mapped into the kernel. 457 */ 458 if (shmfd->shm_kmappings > 0) { 459 VM_OBJECT_WUNLOCK(object); 460 return (EBUSY); 461 } 462 463 /* 464 * Zero the truncated part of the last page. 465 */ 466 base = length & PAGE_MASK; 467 if (base != 0) { 468 idx = OFF_TO_IDX(length); 469 retry: 470 m = vm_page_lookup(object, idx); 471 if (m != NULL) { 472 if (vm_page_sleep_if_busy(m, "shmtrc")) 473 goto retry; 474 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 475 m = vm_page_alloc(object, idx, 476 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 477 if (m == NULL) 478 goto retry; 479 rv = vm_pager_get_pages(object, &m, 1, NULL, 480 NULL); 481 vm_page_lock(m); 482 if (rv == VM_PAGER_OK) { 483 /* 484 * Since the page was not resident, 485 * and therefore not recently 486 * accessed, immediately enqueue it 487 * for asynchronous laundering. The 488 * current operation is not regarded 489 * as an access. 490 */ 491 vm_page_launder(m); 492 vm_page_unlock(m); 493 vm_page_xunbusy(m); 494 } else { 495 vm_page_free(m); 496 vm_page_unlock(m); 497 VM_OBJECT_WUNLOCK(object); 498 return (EIO); 499 } 500 } 501 if (m != NULL) { 502 pmap_zero_page_area(m, base, PAGE_SIZE - base); 503 KASSERT(m->valid == VM_PAGE_BITS_ALL, 504 ("shm_dotruncate: page %p is invalid", m)); 505 vm_page_dirty(m); 506 vm_pager_page_unswapped(m); 507 } 508 } 509 delta = IDX_TO_OFF(object->size - nobjsize); 510 511 /* Toss in memory pages. */ 512 if (nobjsize < object->size) 513 vm_object_page_remove(object, nobjsize, object->size, 514 0); 515 516 /* Toss pages from swap. */ 517 if (object->type == OBJT_SWAP) 518 swap_pager_freespace(object, nobjsize, delta); 519 520 /* Free the swap accounted for shm */ 521 swap_release_by_cred(delta, object->cred); 522 object->charge -= delta; 523 } else { 524 /* Try to reserve additional swap space. */ 525 delta = IDX_TO_OFF(nobjsize - object->size); 526 if (!swap_reserve_by_cred(delta, object->cred)) { 527 VM_OBJECT_WUNLOCK(object); 528 return (ENOMEM); 529 } 530 object->charge += delta; 531 } 532 shmfd->shm_size = length; 533 mtx_lock(&shm_timestamp_lock); 534 vfs_timestamp(&shmfd->shm_ctime); 535 shmfd->shm_mtime = shmfd->shm_ctime; 536 mtx_unlock(&shm_timestamp_lock); 537 object->size = nobjsize; 538 VM_OBJECT_WUNLOCK(object); 539 return (0); 540 } 541 542 /* 543 * shmfd object management including creation and reference counting 544 * routines. 545 */ 546 struct shmfd * 547 shm_alloc(struct ucred *ucred, mode_t mode) 548 { 549 struct shmfd *shmfd; 550 551 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 552 shmfd->shm_size = 0; 553 shmfd->shm_uid = ucred->cr_uid; 554 shmfd->shm_gid = ucred->cr_gid; 555 shmfd->shm_mode = mode; 556 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 557 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 558 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 559 shmfd->shm_object->pg_color = 0; 560 VM_OBJECT_WLOCK(shmfd->shm_object); 561 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 562 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 563 VM_OBJECT_WUNLOCK(shmfd->shm_object); 564 vfs_timestamp(&shmfd->shm_birthtime); 565 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 566 shmfd->shm_birthtime; 567 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 568 refcount_init(&shmfd->shm_refs, 1); 569 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 570 rangelock_init(&shmfd->shm_rl); 571 #ifdef MAC 572 mac_posixshm_init(shmfd); 573 mac_posixshm_create(ucred, shmfd); 574 #endif 575 576 return (shmfd); 577 } 578 579 struct shmfd * 580 shm_hold(struct shmfd *shmfd) 581 { 582 583 refcount_acquire(&shmfd->shm_refs); 584 return (shmfd); 585 } 586 587 void 588 shm_drop(struct shmfd *shmfd) 589 { 590 591 if (refcount_release(&shmfd->shm_refs)) { 592 #ifdef MAC 593 mac_posixshm_destroy(shmfd); 594 #endif 595 rangelock_destroy(&shmfd->shm_rl); 596 mtx_destroy(&shmfd->shm_mtx); 597 vm_object_deallocate(shmfd->shm_object); 598 free(shmfd, M_SHMFD); 599 } 600 } 601 602 /* 603 * Determine if the credentials have sufficient permissions for a 604 * specified combination of FREAD and FWRITE. 605 */ 606 int 607 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 608 { 609 accmode_t accmode; 610 int error; 611 612 accmode = 0; 613 if (flags & FREAD) 614 accmode |= VREAD; 615 if (flags & FWRITE) 616 accmode |= VWRITE; 617 mtx_lock(&shm_timestamp_lock); 618 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 619 accmode, ucred, NULL); 620 mtx_unlock(&shm_timestamp_lock); 621 return (error); 622 } 623 624 /* 625 * Dictionary management. We maintain an in-kernel dictionary to map 626 * paths to shmfd objects. We use the FNV hash on the path to store 627 * the mappings in a hash table. 628 */ 629 static void 630 shm_init(void *arg) 631 { 632 633 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 634 sx_init(&shm_dict_lock, "shm dictionary"); 635 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 636 new_unrhdr64(&shm_ino_unr, 1); 637 shm_dev_ino = devfs_alloc_cdp_inode(); 638 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 639 } 640 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 641 642 static struct shmfd * 643 shm_lookup(char *path, Fnv32_t fnv) 644 { 645 struct shm_mapping *map; 646 647 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 648 if (map->sm_fnv != fnv) 649 continue; 650 if (strcmp(map->sm_path, path) == 0) 651 return (map->sm_shmfd); 652 } 653 654 return (NULL); 655 } 656 657 static void 658 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 659 { 660 struct shm_mapping *map; 661 662 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 663 map->sm_path = path; 664 map->sm_fnv = fnv; 665 map->sm_shmfd = shm_hold(shmfd); 666 shmfd->shm_path = path; 667 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 668 } 669 670 static int 671 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 672 { 673 struct shm_mapping *map; 674 int error; 675 676 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 677 if (map->sm_fnv != fnv) 678 continue; 679 if (strcmp(map->sm_path, path) == 0) { 680 #ifdef MAC 681 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 682 if (error) 683 return (error); 684 #endif 685 error = shm_access(map->sm_shmfd, ucred, 686 FREAD | FWRITE); 687 if (error) 688 return (error); 689 map->sm_shmfd->shm_path = NULL; 690 LIST_REMOVE(map, sm_link); 691 shm_drop(map->sm_shmfd); 692 free(map->sm_path, M_SHMFD); 693 free(map, M_SHMFD); 694 return (0); 695 } 696 } 697 698 return (ENOENT); 699 } 700 701 int 702 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 703 struct filecaps *fcaps) 704 { 705 struct filedesc *fdp; 706 struct shmfd *shmfd; 707 struct file *fp; 708 char *path; 709 const char *pr_path; 710 size_t pr_pathlen; 711 Fnv32_t fnv; 712 mode_t cmode; 713 int fd, error; 714 715 #ifdef CAPABILITY_MODE 716 /* 717 * shm_open(2) is only allowed for anonymous objects. 718 */ 719 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 720 return (ECAPMODE); 721 #endif 722 723 AUDIT_ARG_FFLAGS(flags); 724 AUDIT_ARG_MODE(mode); 725 726 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 727 return (EINVAL); 728 729 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 730 return (EINVAL); 731 732 fdp = td->td_proc->p_fd; 733 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 734 735 error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps); 736 if (error) 737 return (error); 738 739 /* A SHM_ANON path pointer creates an anonymous object. */ 740 if (userpath == SHM_ANON) { 741 /* A read-only anonymous object is pointless. */ 742 if ((flags & O_ACCMODE) == O_RDONLY) { 743 fdclose(td, fp, fd); 744 fdrop(fp, td); 745 return (EINVAL); 746 } 747 shmfd = shm_alloc(td->td_ucred, cmode); 748 } else { 749 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 750 pr_path = td->td_ucred->cr_prison->pr_path; 751 752 /* Construct a full pathname for jailed callers. */ 753 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 754 : strlcpy(path, pr_path, MAXPATHLEN); 755 error = copyinstr(userpath, path + pr_pathlen, 756 MAXPATHLEN - pr_pathlen, NULL); 757 #ifdef KTRACE 758 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 759 ktrnamei(path); 760 #endif 761 /* Require paths to start with a '/' character. */ 762 if (error == 0 && path[pr_pathlen] != '/') 763 error = EINVAL; 764 if (error) { 765 fdclose(td, fp, fd); 766 fdrop(fp, td); 767 free(path, M_SHMFD); 768 return (error); 769 } 770 771 AUDIT_ARG_UPATH1_CANON(path); 772 fnv = fnv_32_str(path, FNV1_32_INIT); 773 sx_xlock(&shm_dict_lock); 774 shmfd = shm_lookup(path, fnv); 775 if (shmfd == NULL) { 776 /* Object does not yet exist, create it if requested. */ 777 if (flags & O_CREAT) { 778 #ifdef MAC 779 error = mac_posixshm_check_create(td->td_ucred, 780 path); 781 if (error == 0) { 782 #endif 783 shmfd = shm_alloc(td->td_ucred, cmode); 784 shm_insert(path, fnv, shmfd); 785 #ifdef MAC 786 } 787 #endif 788 } else { 789 free(path, M_SHMFD); 790 error = ENOENT; 791 } 792 } else { 793 /* 794 * Object already exists, obtain a new 795 * reference if requested and permitted. 796 */ 797 free(path, M_SHMFD); 798 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 799 error = EEXIST; 800 else { 801 #ifdef MAC 802 error = mac_posixshm_check_open(td->td_ucred, 803 shmfd, FFLAGS(flags & O_ACCMODE)); 804 if (error == 0) 805 #endif 806 error = shm_access(shmfd, td->td_ucred, 807 FFLAGS(flags & O_ACCMODE)); 808 } 809 810 /* 811 * Truncate the file back to zero length if 812 * O_TRUNC was specified and the object was 813 * opened with read/write. 814 */ 815 if (error == 0 && 816 (flags & (O_ACCMODE | O_TRUNC)) == 817 (O_RDWR | O_TRUNC)) { 818 #ifdef MAC 819 error = mac_posixshm_check_truncate( 820 td->td_ucred, fp->f_cred, shmfd); 821 if (error == 0) 822 #endif 823 shm_dotruncate(shmfd, 0); 824 } 825 if (error == 0) 826 shm_hold(shmfd); 827 } 828 sx_xunlock(&shm_dict_lock); 829 830 if (error) { 831 fdclose(td, fp, fd); 832 fdrop(fp, td); 833 return (error); 834 } 835 } 836 837 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 838 839 td->td_retval[0] = fd; 840 fdrop(fp, td); 841 842 return (0); 843 } 844 845 /* System calls. */ 846 int 847 sys_shm_open(struct thread *td, struct shm_open_args *uap) 848 { 849 850 return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL)); 851 } 852 853 int 854 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 855 { 856 char *path; 857 const char *pr_path; 858 size_t pr_pathlen; 859 Fnv32_t fnv; 860 int error; 861 862 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 863 pr_path = td->td_ucred->cr_prison->pr_path; 864 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 865 : strlcpy(path, pr_path, MAXPATHLEN); 866 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 867 NULL); 868 if (error) { 869 free(path, M_TEMP); 870 return (error); 871 } 872 #ifdef KTRACE 873 if (KTRPOINT(curthread, KTR_NAMEI)) 874 ktrnamei(path); 875 #endif 876 AUDIT_ARG_UPATH1_CANON(path); 877 fnv = fnv_32_str(path, FNV1_32_INIT); 878 sx_xlock(&shm_dict_lock); 879 error = shm_remove(path, fnv, td->td_ucred); 880 sx_xunlock(&shm_dict_lock); 881 free(path, M_TEMP); 882 883 return (error); 884 } 885 886 int 887 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 888 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 889 vm_ooffset_t foff, struct thread *td) 890 { 891 struct shmfd *shmfd; 892 vm_prot_t maxprot; 893 int error; 894 895 shmfd = fp->f_data; 896 maxprot = VM_PROT_NONE; 897 898 /* FREAD should always be set. */ 899 if ((fp->f_flag & FREAD) != 0) 900 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 901 if ((fp->f_flag & FWRITE) != 0) 902 maxprot |= VM_PROT_WRITE; 903 904 /* Don't permit shared writable mappings on read-only descriptors. */ 905 if ((flags & MAP_SHARED) != 0 && 906 (maxprot & VM_PROT_WRITE) == 0 && 907 (prot & VM_PROT_WRITE) != 0) 908 return (EACCES); 909 maxprot &= cap_maxprot; 910 911 /* See comment in vn_mmap(). */ 912 if ( 913 #ifdef _LP64 914 objsize > OFF_MAX || 915 #endif 916 foff < 0 || foff > OFF_MAX - objsize) 917 return (EINVAL); 918 919 #ifdef MAC 920 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 921 if (error != 0) 922 return (error); 923 #endif 924 925 mtx_lock(&shm_timestamp_lock); 926 vfs_timestamp(&shmfd->shm_atime); 927 mtx_unlock(&shm_timestamp_lock); 928 vm_object_reference(shmfd->shm_object); 929 930 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 931 shmfd->shm_object, foff, FALSE, td); 932 if (error != 0) 933 vm_object_deallocate(shmfd->shm_object); 934 return (error); 935 } 936 937 static int 938 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 939 struct thread *td) 940 { 941 struct shmfd *shmfd; 942 int error; 943 944 error = 0; 945 shmfd = fp->f_data; 946 mtx_lock(&shm_timestamp_lock); 947 /* 948 * SUSv4 says that x bits of permission need not be affected. 949 * Be consistent with our shm_open there. 950 */ 951 #ifdef MAC 952 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 953 if (error != 0) 954 goto out; 955 #endif 956 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 957 shmfd->shm_gid, VADMIN, active_cred, NULL); 958 if (error != 0) 959 goto out; 960 shmfd->shm_mode = mode & ACCESSPERMS; 961 out: 962 mtx_unlock(&shm_timestamp_lock); 963 return (error); 964 } 965 966 static int 967 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 968 struct thread *td) 969 { 970 struct shmfd *shmfd; 971 int error; 972 973 error = 0; 974 shmfd = fp->f_data; 975 mtx_lock(&shm_timestamp_lock); 976 #ifdef MAC 977 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 978 if (error != 0) 979 goto out; 980 #endif 981 if (uid == (uid_t)-1) 982 uid = shmfd->shm_uid; 983 if (gid == (gid_t)-1) 984 gid = shmfd->shm_gid; 985 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 986 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 987 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 988 goto out; 989 shmfd->shm_uid = uid; 990 shmfd->shm_gid = gid; 991 out: 992 mtx_unlock(&shm_timestamp_lock); 993 return (error); 994 } 995 996 /* 997 * Helper routines to allow the backing object of a shared memory file 998 * descriptor to be mapped in the kernel. 999 */ 1000 int 1001 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1002 { 1003 struct shmfd *shmfd; 1004 vm_offset_t kva, ofs; 1005 vm_object_t obj; 1006 int rv; 1007 1008 if (fp->f_type != DTYPE_SHM) 1009 return (EINVAL); 1010 shmfd = fp->f_data; 1011 obj = shmfd->shm_object; 1012 VM_OBJECT_WLOCK(obj); 1013 /* 1014 * XXXRW: This validation is probably insufficient, and subject to 1015 * sign errors. It should be fixed. 1016 */ 1017 if (offset >= shmfd->shm_size || 1018 offset + size > round_page(shmfd->shm_size)) { 1019 VM_OBJECT_WUNLOCK(obj); 1020 return (EINVAL); 1021 } 1022 1023 shmfd->shm_kmappings++; 1024 vm_object_reference_locked(obj); 1025 VM_OBJECT_WUNLOCK(obj); 1026 1027 /* Map the object into the kernel_map and wire it. */ 1028 kva = vm_map_min(kernel_map); 1029 ofs = offset & PAGE_MASK; 1030 offset = trunc_page(offset); 1031 size = round_page(size + ofs); 1032 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1033 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1034 VM_PROT_READ | VM_PROT_WRITE, 0); 1035 if (rv == KERN_SUCCESS) { 1036 rv = vm_map_wire(kernel_map, kva, kva + size, 1037 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1038 if (rv == KERN_SUCCESS) { 1039 *memp = (void *)(kva + ofs); 1040 return (0); 1041 } 1042 vm_map_remove(kernel_map, kva, kva + size); 1043 } else 1044 vm_object_deallocate(obj); 1045 1046 /* On failure, drop our mapping reference. */ 1047 VM_OBJECT_WLOCK(obj); 1048 shmfd->shm_kmappings--; 1049 VM_OBJECT_WUNLOCK(obj); 1050 1051 return (vm_mmap_to_errno(rv)); 1052 } 1053 1054 /* 1055 * We require the caller to unmap the entire entry. This allows us to 1056 * safely decrement shm_kmappings when a mapping is removed. 1057 */ 1058 int 1059 shm_unmap(struct file *fp, void *mem, size_t size) 1060 { 1061 struct shmfd *shmfd; 1062 vm_map_entry_t entry; 1063 vm_offset_t kva, ofs; 1064 vm_object_t obj; 1065 vm_pindex_t pindex; 1066 vm_prot_t prot; 1067 boolean_t wired; 1068 vm_map_t map; 1069 int rv; 1070 1071 if (fp->f_type != DTYPE_SHM) 1072 return (EINVAL); 1073 shmfd = fp->f_data; 1074 kva = (vm_offset_t)mem; 1075 ofs = kva & PAGE_MASK; 1076 kva = trunc_page(kva); 1077 size = round_page(size + ofs); 1078 map = kernel_map; 1079 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1080 &obj, &pindex, &prot, &wired); 1081 if (rv != KERN_SUCCESS) 1082 return (EINVAL); 1083 if (entry->start != kva || entry->end != kva + size) { 1084 vm_map_lookup_done(map, entry); 1085 return (EINVAL); 1086 } 1087 vm_map_lookup_done(map, entry); 1088 if (obj != shmfd->shm_object) 1089 return (EINVAL); 1090 vm_map_remove(map, kva, kva + size); 1091 VM_OBJECT_WLOCK(obj); 1092 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1093 shmfd->shm_kmappings--; 1094 VM_OBJECT_WUNLOCK(obj); 1095 return (0); 1096 } 1097 1098 static int 1099 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1100 { 1101 const char *path, *pr_path; 1102 size_t pr_pathlen; 1103 bool visible; 1104 1105 sx_assert(&shm_dict_lock, SA_LOCKED); 1106 kif->kf_type = KF_TYPE_SHM; 1107 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1108 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1109 if (shmfd->shm_path != NULL) { 1110 if (shmfd->shm_path != NULL) { 1111 path = shmfd->shm_path; 1112 pr_path = curthread->td_ucred->cr_prison->pr_path; 1113 if (strcmp(pr_path, "/") != 0) { 1114 /* Return the jail-rooted pathname. */ 1115 pr_pathlen = strlen(pr_path); 1116 visible = strncmp(path, pr_path, pr_pathlen) 1117 == 0 && path[pr_pathlen] == '/'; 1118 if (list && !visible) 1119 return (EPERM); 1120 if (visible) 1121 path += pr_pathlen; 1122 } 1123 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1124 } 1125 } 1126 return (0); 1127 } 1128 1129 static int 1130 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1131 struct filedesc *fdp __unused) 1132 { 1133 int res; 1134 1135 sx_slock(&shm_dict_lock); 1136 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1137 sx_sunlock(&shm_dict_lock); 1138 return (res); 1139 } 1140 1141 static int 1142 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1143 { 1144 struct shm_mapping *shmm; 1145 struct sbuf sb; 1146 struct kinfo_file kif; 1147 u_long i; 1148 ssize_t curlen; 1149 int error, error2; 1150 1151 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1152 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1153 curlen = 0; 1154 error = 0; 1155 sx_slock(&shm_dict_lock); 1156 for (i = 0; i < shm_hash + 1; i++) { 1157 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1158 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1159 &kif, true); 1160 if (error == EPERM) 1161 continue; 1162 if (error != 0) 1163 break; 1164 pack_kinfo(&kif); 1165 if (req->oldptr != NULL && 1166 kif.kf_structsize + curlen > req->oldlen) 1167 break; 1168 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1169 0 : ENOMEM; 1170 if (error != 0) 1171 break; 1172 curlen += kif.kf_structsize; 1173 } 1174 } 1175 sx_sunlock(&shm_dict_lock); 1176 error2 = sbuf_finish(&sb); 1177 sbuf_delete(&sb); 1178 return (error != 0 ? error : error2); 1179 } 1180 1181 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1182 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1183 NULL, 0, sysctl_posix_shm_list, "", 1184 "POSIX SHM list"); 1185