1 /*- 2 * Copyright (c) 2006, 2011 Robert N. M. Watson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 /* 28 * Support for shared swap-backed anonymous memory objects via 29 * shm_open(2) and shm_unlink(2). While most of the implementation is 30 * here, vm_mmap.c contains mapping logic changes. 31 * 32 * TODO: 33 * 34 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) 35 * and ipcrm(1) be expanded or should new tools to manage both POSIX 36 * kernel semaphores and POSIX shared memory be written? 37 * 38 * (2) Add support for this file type to fstat(1). 39 * 40 * (3) Resource limits? Does this need its own resource limits or are the 41 * existing limits in mmap(2) sufficient? 42 */ 43 44 #include <sys/cdefs.h> 45 __FBSDID("$FreeBSD$"); 46 47 #include "opt_capsicum.h" 48 #include "opt_ktrace.h" 49 50 #include <sys/param.h> 51 #include <sys/capsicum.h> 52 #include <sys/conf.h> 53 #include <sys/fcntl.h> 54 #include <sys/file.h> 55 #include <sys/filedesc.h> 56 #include <sys/fnv_hash.h> 57 #include <sys/kernel.h> 58 #include <sys/uio.h> 59 #include <sys/signal.h> 60 #include <sys/ktrace.h> 61 #include <sys/lock.h> 62 #include <sys/malloc.h> 63 #include <sys/mman.h> 64 #include <sys/mutex.h> 65 #include <sys/priv.h> 66 #include <sys/proc.h> 67 #include <sys/refcount.h> 68 #include <sys/resourcevar.h> 69 #include <sys/rwlock.h> 70 #include <sys/stat.h> 71 #include <sys/sysctl.h> 72 #include <sys/sysproto.h> 73 #include <sys/systm.h> 74 #include <sys/sx.h> 75 #include <sys/time.h> 76 #include <sys/vnode.h> 77 #include <sys/unistd.h> 78 79 #include <security/mac/mac_framework.h> 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_extern.h> 85 #include <vm/vm_map.h> 86 #include <vm/vm_kern.h> 87 #include <vm/vm_object.h> 88 #include <vm/vm_page.h> 89 #include <vm/vm_pageout.h> 90 #include <vm/vm_pager.h> 91 #include <vm/swap_pager.h> 92 93 struct shm_mapping { 94 char *sm_path; 95 Fnv32_t sm_fnv; 96 struct shmfd *sm_shmfd; 97 LIST_ENTRY(shm_mapping) sm_link; 98 }; 99 100 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 101 static LIST_HEAD(, shm_mapping) *shm_dictionary; 102 static struct sx shm_dict_lock; 103 static struct mtx shm_timestamp_lock; 104 static u_long shm_hash; 105 static struct unrhdr *shm_ino_unr; 106 static dev_t shm_dev_ino; 107 108 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 109 110 static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags); 111 static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode); 112 static void shm_init(void *arg); 113 static void shm_drop(struct shmfd *shmfd); 114 static struct shmfd *shm_hold(struct shmfd *shmfd); 115 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 116 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 117 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 118 static int shm_dotruncate(struct shmfd *shmfd, off_t length); 119 120 static fo_rdwr_t shm_read; 121 static fo_rdwr_t shm_write; 122 static fo_truncate_t shm_truncate; 123 static fo_stat_t shm_stat; 124 static fo_close_t shm_close; 125 static fo_chmod_t shm_chmod; 126 static fo_chown_t shm_chown; 127 static fo_seek_t shm_seek; 128 129 /* File descriptor operations. */ 130 static struct fileops shm_ops = { 131 .fo_read = shm_read, 132 .fo_write = shm_write, 133 .fo_truncate = shm_truncate, 134 .fo_ioctl = invfo_ioctl, 135 .fo_poll = invfo_poll, 136 .fo_kqfilter = invfo_kqfilter, 137 .fo_stat = shm_stat, 138 .fo_close = shm_close, 139 .fo_chmod = shm_chmod, 140 .fo_chown = shm_chown, 141 .fo_sendfile = vn_sendfile, 142 .fo_seek = shm_seek, 143 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 144 }; 145 146 FEATURE(posix_shm, "POSIX shared memory"); 147 148 static int 149 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 150 { 151 vm_page_t m; 152 vm_pindex_t idx; 153 size_t tlen; 154 int error, offset, rv; 155 156 idx = OFF_TO_IDX(uio->uio_offset); 157 offset = uio->uio_offset & PAGE_MASK; 158 tlen = MIN(PAGE_SIZE - offset, len); 159 160 VM_OBJECT_WLOCK(obj); 161 162 /* 163 * Parallel reads of the page content from disk are prevented 164 * by exclusive busy. 165 * 166 * Although the tmpfs vnode lock is held here, it is 167 * nonetheless safe to sleep waiting for a free page. The 168 * pageout daemon does not need to acquire the tmpfs vnode 169 * lock to page out tobj's pages because tobj is a OBJT_SWAP 170 * type object. 171 */ 172 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL); 173 if (m->valid != VM_PAGE_BITS_ALL) { 174 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 175 rv = vm_pager_get_pages(obj, &m, 1, 0); 176 m = vm_page_lookup(obj, idx); 177 if (m == NULL) { 178 printf( 179 "uiomove_object: vm_obj %p idx %jd null lookup rv %d\n", 180 obj, idx, rv); 181 VM_OBJECT_WUNLOCK(obj); 182 return (EIO); 183 } 184 if (rv != VM_PAGER_OK) { 185 printf( 186 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 187 obj, idx, m->valid, rv); 188 vm_page_lock(m); 189 vm_page_free(m); 190 vm_page_unlock(m); 191 VM_OBJECT_WUNLOCK(obj); 192 return (EIO); 193 } 194 } else 195 vm_page_zero_invalid(m, TRUE); 196 } 197 vm_page_xunbusy(m); 198 vm_page_lock(m); 199 vm_page_hold(m); 200 if (m->queue == PQ_NONE) { 201 vm_page_deactivate(m); 202 } else { 203 /* Requeue to maintain LRU ordering. */ 204 vm_page_requeue(m); 205 } 206 vm_page_unlock(m); 207 VM_OBJECT_WUNLOCK(obj); 208 error = uiomove_fromphys(&m, offset, tlen, uio); 209 if (uio->uio_rw == UIO_WRITE && error == 0) { 210 VM_OBJECT_WLOCK(obj); 211 vm_page_dirty(m); 212 vm_pager_page_unswapped(m); 213 VM_OBJECT_WUNLOCK(obj); 214 } 215 vm_page_lock(m); 216 vm_page_unhold(m); 217 vm_page_unlock(m); 218 219 return (error); 220 } 221 222 int 223 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 224 { 225 ssize_t resid; 226 size_t len; 227 int error; 228 229 error = 0; 230 while ((resid = uio->uio_resid) > 0) { 231 if (obj_size <= uio->uio_offset) 232 break; 233 len = MIN(obj_size - uio->uio_offset, resid); 234 if (len == 0) 235 break; 236 error = uiomove_object_page(obj, len, uio); 237 if (error != 0 || resid == uio->uio_resid) 238 break; 239 } 240 return (error); 241 } 242 243 static int 244 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 245 { 246 struct shmfd *shmfd; 247 off_t foffset; 248 int error; 249 250 shmfd = fp->f_data; 251 foffset = foffset_lock(fp, 0); 252 error = 0; 253 switch (whence) { 254 case L_INCR: 255 if (foffset < 0 || 256 (offset > 0 && foffset > OFF_MAX - offset)) { 257 error = EOVERFLOW; 258 break; 259 } 260 offset += foffset; 261 break; 262 case L_XTND: 263 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 264 error = EOVERFLOW; 265 break; 266 } 267 offset += shmfd->shm_size; 268 break; 269 case L_SET: 270 break; 271 default: 272 error = EINVAL; 273 } 274 if (error == 0) { 275 if (offset < 0 || offset > shmfd->shm_size) 276 error = EINVAL; 277 else 278 td->td_uretoff.tdu_off = offset; 279 } 280 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 281 return (error); 282 } 283 284 static int 285 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 286 int flags, struct thread *td) 287 { 288 struct shmfd *shmfd; 289 void *rl_cookie; 290 int error; 291 292 shmfd = fp->f_data; 293 foffset_lock_uio(fp, uio, flags); 294 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 295 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 296 #ifdef MAC 297 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 298 if (error) 299 return (error); 300 #endif 301 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 302 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 303 foffset_unlock_uio(fp, uio, flags); 304 return (error); 305 } 306 307 static int 308 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 309 int flags, struct thread *td) 310 { 311 struct shmfd *shmfd; 312 void *rl_cookie; 313 int error; 314 315 shmfd = fp->f_data; 316 #ifdef MAC 317 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 318 if (error) 319 return (error); 320 #endif 321 foffset_lock_uio(fp, uio, flags); 322 if ((flags & FOF_OFFSET) == 0) { 323 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 324 &shmfd->shm_mtx); 325 } else { 326 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 327 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 328 } 329 330 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 331 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 332 foffset_unlock_uio(fp, uio, flags); 333 return (error); 334 } 335 336 static int 337 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 338 struct thread *td) 339 { 340 struct shmfd *shmfd; 341 #ifdef MAC 342 int error; 343 #endif 344 345 shmfd = fp->f_data; 346 #ifdef MAC 347 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 348 if (error) 349 return (error); 350 #endif 351 return (shm_dotruncate(shmfd, length)); 352 } 353 354 static int 355 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 356 struct thread *td) 357 { 358 struct shmfd *shmfd; 359 #ifdef MAC 360 int error; 361 #endif 362 363 shmfd = fp->f_data; 364 365 #ifdef MAC 366 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 367 if (error) 368 return (error); 369 #endif 370 371 /* 372 * Attempt to return sanish values for fstat() on a memory file 373 * descriptor. 374 */ 375 bzero(sb, sizeof(*sb)); 376 sb->st_blksize = PAGE_SIZE; 377 sb->st_size = shmfd->shm_size; 378 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 379 mtx_lock(&shm_timestamp_lock); 380 sb->st_atim = shmfd->shm_atime; 381 sb->st_ctim = shmfd->shm_ctime; 382 sb->st_mtim = shmfd->shm_mtime; 383 sb->st_birthtim = shmfd->shm_birthtime; 384 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 385 sb->st_uid = shmfd->shm_uid; 386 sb->st_gid = shmfd->shm_gid; 387 mtx_unlock(&shm_timestamp_lock); 388 sb->st_dev = shm_dev_ino; 389 sb->st_ino = shmfd->shm_ino; 390 391 return (0); 392 } 393 394 static int 395 shm_close(struct file *fp, struct thread *td) 396 { 397 struct shmfd *shmfd; 398 399 shmfd = fp->f_data; 400 fp->f_data = NULL; 401 shm_drop(shmfd); 402 403 return (0); 404 } 405 406 static int 407 shm_dotruncate(struct shmfd *shmfd, off_t length) 408 { 409 vm_object_t object; 410 vm_page_t m, ma[1]; 411 vm_pindex_t idx, nobjsize; 412 vm_ooffset_t delta; 413 int base, rv; 414 415 object = shmfd->shm_object; 416 VM_OBJECT_WLOCK(object); 417 if (length == shmfd->shm_size) { 418 VM_OBJECT_WUNLOCK(object); 419 return (0); 420 } 421 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 422 423 /* Are we shrinking? If so, trim the end. */ 424 if (length < shmfd->shm_size) { 425 /* 426 * Disallow any requests to shrink the size if this 427 * object is mapped into the kernel. 428 */ 429 if (shmfd->shm_kmappings > 0) { 430 VM_OBJECT_WUNLOCK(object); 431 return (EBUSY); 432 } 433 434 /* 435 * Zero the truncated part of the last page. 436 */ 437 base = length & PAGE_MASK; 438 if (base != 0) { 439 idx = OFF_TO_IDX(length); 440 retry: 441 m = vm_page_lookup(object, idx); 442 if (m != NULL) { 443 if (vm_page_sleep_if_busy(m, "shmtrc")) 444 goto retry; 445 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 446 m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 447 if (m == NULL) { 448 VM_OBJECT_WUNLOCK(object); 449 VM_WAIT; 450 VM_OBJECT_WLOCK(object); 451 goto retry; 452 } else if (m->valid != VM_PAGE_BITS_ALL) { 453 ma[0] = m; 454 rv = vm_pager_get_pages(object, ma, 1, 455 0); 456 m = vm_page_lookup(object, idx); 457 } else 458 /* A cached page was reactivated. */ 459 rv = VM_PAGER_OK; 460 vm_page_lock(m); 461 if (rv == VM_PAGER_OK) { 462 vm_page_deactivate(m); 463 vm_page_unlock(m); 464 vm_page_xunbusy(m); 465 } else { 466 vm_page_free(m); 467 vm_page_unlock(m); 468 VM_OBJECT_WUNLOCK(object); 469 return (EIO); 470 } 471 } 472 if (m != NULL) { 473 pmap_zero_page_area(m, base, PAGE_SIZE - base); 474 KASSERT(m->valid == VM_PAGE_BITS_ALL, 475 ("shm_dotruncate: page %p is invalid", m)); 476 vm_page_dirty(m); 477 vm_pager_page_unswapped(m); 478 } 479 } 480 delta = ptoa(object->size - nobjsize); 481 482 /* Toss in memory pages. */ 483 if (nobjsize < object->size) 484 vm_object_page_remove(object, nobjsize, object->size, 485 0); 486 487 /* Toss pages from swap. */ 488 if (object->type == OBJT_SWAP) 489 swap_pager_freespace(object, nobjsize, delta); 490 491 /* Free the swap accounted for shm */ 492 swap_release_by_cred(delta, object->cred); 493 object->charge -= delta; 494 } else { 495 /* Attempt to reserve the swap */ 496 delta = ptoa(nobjsize - object->size); 497 if (!swap_reserve_by_cred(delta, object->cred)) { 498 VM_OBJECT_WUNLOCK(object); 499 return (ENOMEM); 500 } 501 object->charge += delta; 502 } 503 shmfd->shm_size = length; 504 mtx_lock(&shm_timestamp_lock); 505 vfs_timestamp(&shmfd->shm_ctime); 506 shmfd->shm_mtime = shmfd->shm_ctime; 507 mtx_unlock(&shm_timestamp_lock); 508 object->size = nobjsize; 509 VM_OBJECT_WUNLOCK(object); 510 return (0); 511 } 512 513 /* 514 * shmfd object management including creation and reference counting 515 * routines. 516 */ 517 static struct shmfd * 518 shm_alloc(struct ucred *ucred, mode_t mode) 519 { 520 struct shmfd *shmfd; 521 int ino; 522 523 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 524 shmfd->shm_size = 0; 525 shmfd->shm_uid = ucred->cr_uid; 526 shmfd->shm_gid = ucred->cr_gid; 527 shmfd->shm_mode = mode; 528 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 529 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 530 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 531 VM_OBJECT_WLOCK(shmfd->shm_object); 532 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 533 vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT); 534 VM_OBJECT_WUNLOCK(shmfd->shm_object); 535 vfs_timestamp(&shmfd->shm_birthtime); 536 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 537 shmfd->shm_birthtime; 538 ino = alloc_unr(shm_ino_unr); 539 if (ino == -1) 540 shmfd->shm_ino = 0; 541 else 542 shmfd->shm_ino = ino; 543 refcount_init(&shmfd->shm_refs, 1); 544 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 545 rangelock_init(&shmfd->shm_rl); 546 #ifdef MAC 547 mac_posixshm_init(shmfd); 548 mac_posixshm_create(ucred, shmfd); 549 #endif 550 551 return (shmfd); 552 } 553 554 static struct shmfd * 555 shm_hold(struct shmfd *shmfd) 556 { 557 558 refcount_acquire(&shmfd->shm_refs); 559 return (shmfd); 560 } 561 562 static void 563 shm_drop(struct shmfd *shmfd) 564 { 565 566 if (refcount_release(&shmfd->shm_refs)) { 567 #ifdef MAC 568 mac_posixshm_destroy(shmfd); 569 #endif 570 rangelock_destroy(&shmfd->shm_rl); 571 mtx_destroy(&shmfd->shm_mtx); 572 vm_object_deallocate(shmfd->shm_object); 573 if (shmfd->shm_ino != 0) 574 free_unr(shm_ino_unr, shmfd->shm_ino); 575 free(shmfd, M_SHMFD); 576 } 577 } 578 579 /* 580 * Determine if the credentials have sufficient permissions for a 581 * specified combination of FREAD and FWRITE. 582 */ 583 static int 584 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 585 { 586 accmode_t accmode; 587 int error; 588 589 accmode = 0; 590 if (flags & FREAD) 591 accmode |= VREAD; 592 if (flags & FWRITE) 593 accmode |= VWRITE; 594 mtx_lock(&shm_timestamp_lock); 595 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 596 accmode, ucred, NULL); 597 mtx_unlock(&shm_timestamp_lock); 598 return (error); 599 } 600 601 /* 602 * Dictionary management. We maintain an in-kernel dictionary to map 603 * paths to shmfd objects. We use the FNV hash on the path to store 604 * the mappings in a hash table. 605 */ 606 static void 607 shm_init(void *arg) 608 { 609 610 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 611 sx_init(&shm_dict_lock, "shm dictionary"); 612 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 613 shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL); 614 KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized")); 615 shm_dev_ino = devfs_alloc_cdp_inode(); 616 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 617 } 618 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 619 620 static struct shmfd * 621 shm_lookup(char *path, Fnv32_t fnv) 622 { 623 struct shm_mapping *map; 624 625 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 626 if (map->sm_fnv != fnv) 627 continue; 628 if (strcmp(map->sm_path, path) == 0) 629 return (map->sm_shmfd); 630 } 631 632 return (NULL); 633 } 634 635 static void 636 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 637 { 638 struct shm_mapping *map; 639 640 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 641 map->sm_path = path; 642 map->sm_fnv = fnv; 643 map->sm_shmfd = shm_hold(shmfd); 644 shmfd->shm_path = path; 645 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 646 } 647 648 static int 649 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 650 { 651 struct shm_mapping *map; 652 int error; 653 654 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 655 if (map->sm_fnv != fnv) 656 continue; 657 if (strcmp(map->sm_path, path) == 0) { 658 #ifdef MAC 659 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 660 if (error) 661 return (error); 662 #endif 663 error = shm_access(map->sm_shmfd, ucred, 664 FREAD | FWRITE); 665 if (error) 666 return (error); 667 map->sm_shmfd->shm_path = NULL; 668 LIST_REMOVE(map, sm_link); 669 shm_drop(map->sm_shmfd); 670 free(map->sm_path, M_SHMFD); 671 free(map, M_SHMFD); 672 return (0); 673 } 674 } 675 676 return (ENOENT); 677 } 678 679 /* System calls. */ 680 int 681 sys_shm_open(struct thread *td, struct shm_open_args *uap) 682 { 683 struct filedesc *fdp; 684 struct shmfd *shmfd; 685 struct file *fp; 686 char *path; 687 Fnv32_t fnv; 688 mode_t cmode; 689 int fd, error; 690 691 #ifdef CAPABILITY_MODE 692 /* 693 * shm_open(2) is only allowed for anonymous objects. 694 */ 695 if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 696 return (ECAPMODE); 697 #endif 698 699 if ((uap->flags & O_ACCMODE) != O_RDONLY && 700 (uap->flags & O_ACCMODE) != O_RDWR) 701 return (EINVAL); 702 703 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 704 return (EINVAL); 705 706 fdp = td->td_proc->p_fd; 707 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 708 709 error = falloc(td, &fp, &fd, O_CLOEXEC); 710 if (error) 711 return (error); 712 713 /* A SHM_ANON path pointer creates an anonymous object. */ 714 if (uap->path == SHM_ANON) { 715 /* A read-only anonymous object is pointless. */ 716 if ((uap->flags & O_ACCMODE) == O_RDONLY) { 717 fdclose(fdp, fp, fd, td); 718 fdrop(fp, td); 719 return (EINVAL); 720 } 721 shmfd = shm_alloc(td->td_ucred, cmode); 722 } else { 723 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 724 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 725 #ifdef KTRACE 726 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 727 ktrnamei(path); 728 #endif 729 /* Require paths to start with a '/' character. */ 730 if (error == 0 && path[0] != '/') 731 error = EINVAL; 732 if (error) { 733 fdclose(fdp, fp, fd, td); 734 fdrop(fp, td); 735 free(path, M_SHMFD); 736 return (error); 737 } 738 739 fnv = fnv_32_str(path, FNV1_32_INIT); 740 sx_xlock(&shm_dict_lock); 741 shmfd = shm_lookup(path, fnv); 742 if (shmfd == NULL) { 743 /* Object does not yet exist, create it if requested. */ 744 if (uap->flags & O_CREAT) { 745 #ifdef MAC 746 error = mac_posixshm_check_create(td->td_ucred, 747 path); 748 if (error == 0) { 749 #endif 750 shmfd = shm_alloc(td->td_ucred, cmode); 751 shm_insert(path, fnv, shmfd); 752 #ifdef MAC 753 } 754 #endif 755 } else { 756 free(path, M_SHMFD); 757 error = ENOENT; 758 } 759 } else { 760 /* 761 * Object already exists, obtain a new 762 * reference if requested and permitted. 763 */ 764 free(path, M_SHMFD); 765 if ((uap->flags & (O_CREAT | O_EXCL)) == 766 (O_CREAT | O_EXCL)) 767 error = EEXIST; 768 else { 769 #ifdef MAC 770 error = mac_posixshm_check_open(td->td_ucred, 771 shmfd, FFLAGS(uap->flags & O_ACCMODE)); 772 if (error == 0) 773 #endif 774 error = shm_access(shmfd, td->td_ucred, 775 FFLAGS(uap->flags & O_ACCMODE)); 776 } 777 778 /* 779 * Truncate the file back to zero length if 780 * O_TRUNC was specified and the object was 781 * opened with read/write. 782 */ 783 if (error == 0 && 784 (uap->flags & (O_ACCMODE | O_TRUNC)) == 785 (O_RDWR | O_TRUNC)) { 786 #ifdef MAC 787 error = mac_posixshm_check_truncate( 788 td->td_ucred, fp->f_cred, shmfd); 789 if (error == 0) 790 #endif 791 shm_dotruncate(shmfd, 0); 792 } 793 if (error == 0) 794 shm_hold(shmfd); 795 } 796 sx_xunlock(&shm_dict_lock); 797 798 if (error) { 799 fdclose(fdp, fp, fd, td); 800 fdrop(fp, td); 801 return (error); 802 } 803 } 804 805 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 806 807 td->td_retval[0] = fd; 808 fdrop(fp, td); 809 810 return (0); 811 } 812 813 int 814 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 815 { 816 char *path; 817 Fnv32_t fnv; 818 int error; 819 820 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 821 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 822 if (error) { 823 free(path, M_TEMP); 824 return (error); 825 } 826 #ifdef KTRACE 827 if (KTRPOINT(curthread, KTR_NAMEI)) 828 ktrnamei(path); 829 #endif 830 fnv = fnv_32_str(path, FNV1_32_INIT); 831 sx_xlock(&shm_dict_lock); 832 error = shm_remove(path, fnv, td->td_ucred); 833 sx_xunlock(&shm_dict_lock); 834 free(path, M_TEMP); 835 836 return (error); 837 } 838 839 /* 840 * mmap() helper to validate mmap() requests against shm object state 841 * and give mmap() the vm_object to use for the mapping. 842 */ 843 int 844 shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff, 845 vm_object_t *obj) 846 { 847 848 /* 849 * XXXRW: This validation is probably insufficient, and subject to 850 * sign errors. It should be fixed. 851 */ 852 if (foff >= shmfd->shm_size || 853 foff + objsize > round_page(shmfd->shm_size)) 854 return (EINVAL); 855 856 mtx_lock(&shm_timestamp_lock); 857 vfs_timestamp(&shmfd->shm_atime); 858 mtx_unlock(&shm_timestamp_lock); 859 vm_object_reference(shmfd->shm_object); 860 *obj = shmfd->shm_object; 861 return (0); 862 } 863 864 static int 865 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 866 struct thread *td) 867 { 868 struct shmfd *shmfd; 869 int error; 870 871 error = 0; 872 shmfd = fp->f_data; 873 mtx_lock(&shm_timestamp_lock); 874 /* 875 * SUSv4 says that x bits of permission need not be affected. 876 * Be consistent with our shm_open there. 877 */ 878 #ifdef MAC 879 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 880 if (error != 0) 881 goto out; 882 #endif 883 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 884 shmfd->shm_gid, VADMIN, active_cred, NULL); 885 if (error != 0) 886 goto out; 887 shmfd->shm_mode = mode & ACCESSPERMS; 888 out: 889 mtx_unlock(&shm_timestamp_lock); 890 return (error); 891 } 892 893 static int 894 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 895 struct thread *td) 896 { 897 struct shmfd *shmfd; 898 int error; 899 900 error = 0; 901 shmfd = fp->f_data; 902 mtx_lock(&shm_timestamp_lock); 903 #ifdef MAC 904 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 905 if (error != 0) 906 goto out; 907 #endif 908 if (uid == (uid_t)-1) 909 uid = shmfd->shm_uid; 910 if (gid == (gid_t)-1) 911 gid = shmfd->shm_gid; 912 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 913 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 914 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 915 goto out; 916 shmfd->shm_uid = uid; 917 shmfd->shm_gid = gid; 918 out: 919 mtx_unlock(&shm_timestamp_lock); 920 return (error); 921 } 922 923 /* 924 * Helper routines to allow the backing object of a shared memory file 925 * descriptor to be mapped in the kernel. 926 */ 927 int 928 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 929 { 930 struct shmfd *shmfd; 931 vm_offset_t kva, ofs; 932 vm_object_t obj; 933 int rv; 934 935 if (fp->f_type != DTYPE_SHM) 936 return (EINVAL); 937 shmfd = fp->f_data; 938 obj = shmfd->shm_object; 939 VM_OBJECT_WLOCK(obj); 940 /* 941 * XXXRW: This validation is probably insufficient, and subject to 942 * sign errors. It should be fixed. 943 */ 944 if (offset >= shmfd->shm_size || 945 offset + size > round_page(shmfd->shm_size)) { 946 VM_OBJECT_WUNLOCK(obj); 947 return (EINVAL); 948 } 949 950 shmfd->shm_kmappings++; 951 vm_object_reference_locked(obj); 952 VM_OBJECT_WUNLOCK(obj); 953 954 /* Map the object into the kernel_map and wire it. */ 955 kva = vm_map_min(kernel_map); 956 ofs = offset & PAGE_MASK; 957 offset = trunc_page(offset); 958 size = round_page(size + ofs); 959 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 960 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 961 VM_PROT_READ | VM_PROT_WRITE, 0); 962 if (rv == KERN_SUCCESS) { 963 rv = vm_map_wire(kernel_map, kva, kva + size, 964 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 965 if (rv == KERN_SUCCESS) { 966 *memp = (void *)(kva + ofs); 967 return (0); 968 } 969 vm_map_remove(kernel_map, kva, kva + size); 970 } else 971 vm_object_deallocate(obj); 972 973 /* On failure, drop our mapping reference. */ 974 VM_OBJECT_WLOCK(obj); 975 shmfd->shm_kmappings--; 976 VM_OBJECT_WUNLOCK(obj); 977 978 return (vm_mmap_to_errno(rv)); 979 } 980 981 /* 982 * We require the caller to unmap the entire entry. This allows us to 983 * safely decrement shm_kmappings when a mapping is removed. 984 */ 985 int 986 shm_unmap(struct file *fp, void *mem, size_t size) 987 { 988 struct shmfd *shmfd; 989 vm_map_entry_t entry; 990 vm_offset_t kva, ofs; 991 vm_object_t obj; 992 vm_pindex_t pindex; 993 vm_prot_t prot; 994 boolean_t wired; 995 vm_map_t map; 996 int rv; 997 998 if (fp->f_type != DTYPE_SHM) 999 return (EINVAL); 1000 shmfd = fp->f_data; 1001 kva = (vm_offset_t)mem; 1002 ofs = kva & PAGE_MASK; 1003 kva = trunc_page(kva); 1004 size = round_page(size + ofs); 1005 map = kernel_map; 1006 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1007 &obj, &pindex, &prot, &wired); 1008 if (rv != KERN_SUCCESS) 1009 return (EINVAL); 1010 if (entry->start != kva || entry->end != kva + size) { 1011 vm_map_lookup_done(map, entry); 1012 return (EINVAL); 1013 } 1014 vm_map_lookup_done(map, entry); 1015 if (obj != shmfd->shm_object) 1016 return (EINVAL); 1017 vm_map_remove(map, kva, kva + size); 1018 VM_OBJECT_WLOCK(obj); 1019 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1020 shmfd->shm_kmappings--; 1021 VM_OBJECT_WUNLOCK(obj); 1022 return (0); 1023 } 1024 1025 void 1026 shm_path(struct shmfd *shmfd, char *path, size_t size) 1027 { 1028 1029 if (shmfd->shm_path == NULL) 1030 return; 1031 sx_slock(&shm_dict_lock); 1032 if (shmfd->shm_path != NULL) 1033 strlcpy(path, shmfd->shm_path, size); 1034 sx_sunlock(&shm_dict_lock); 1035 } 1036