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/syscallsubr.h> 72 #include <sys/sysctl.h> 73 #include <sys/sysproto.h> 74 #include <sys/systm.h> 75 #include <sys/sx.h> 76 #include <sys/time.h> 77 #include <sys/vnode.h> 78 #include <sys/unistd.h> 79 #include <sys/user.h> 80 81 #include <security/mac/mac_framework.h> 82 83 #include <vm/vm.h> 84 #include <vm/vm_param.h> 85 #include <vm/pmap.h> 86 #include <vm/vm_extern.h> 87 #include <vm/vm_map.h> 88 #include <vm/vm_kern.h> 89 #include <vm/vm_object.h> 90 #include <vm/vm_page.h> 91 #include <vm/vm_pageout.h> 92 #include <vm/vm_pager.h> 93 #include <vm/swap_pager.h> 94 95 struct shm_mapping { 96 char *sm_path; 97 Fnv32_t sm_fnv; 98 struct shmfd *sm_shmfd; 99 LIST_ENTRY(shm_mapping) sm_link; 100 }; 101 102 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 103 static LIST_HEAD(, shm_mapping) *shm_dictionary; 104 static struct sx shm_dict_lock; 105 static struct mtx shm_timestamp_lock; 106 static u_long shm_hash; 107 static struct unrhdr *shm_ino_unr; 108 static dev_t shm_dev_ino; 109 110 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 111 112 static void shm_init(void *arg); 113 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 114 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 115 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 116 117 static fo_rdwr_t shm_read; 118 static fo_rdwr_t shm_write; 119 static fo_truncate_t shm_truncate; 120 static fo_stat_t shm_stat; 121 static fo_close_t shm_close; 122 static fo_chmod_t shm_chmod; 123 static fo_chown_t shm_chown; 124 static fo_seek_t shm_seek; 125 static fo_fill_kinfo_t shm_fill_kinfo; 126 static fo_mmap_t shm_mmap; 127 128 /* File descriptor operations. */ 129 struct fileops shm_ops = { 130 .fo_read = shm_read, 131 .fo_write = shm_write, 132 .fo_truncate = shm_truncate, 133 .fo_ioctl = invfo_ioctl, 134 .fo_poll = invfo_poll, 135 .fo_kqfilter = invfo_kqfilter, 136 .fo_stat = shm_stat, 137 .fo_close = shm_close, 138 .fo_chmod = shm_chmod, 139 .fo_chown = shm_chown, 140 .fo_sendfile = vn_sendfile, 141 .fo_seek = shm_seek, 142 .fo_fill_kinfo = shm_fill_kinfo, 143 .fo_mmap = shm_mmap, 144 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 145 }; 146 147 FEATURE(posix_shm, "POSIX shared memory"); 148 149 static int 150 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 151 { 152 vm_page_t m; 153 vm_pindex_t idx; 154 size_t tlen; 155 int error, offset, rv; 156 157 idx = OFF_TO_IDX(uio->uio_offset); 158 offset = uio->uio_offset & PAGE_MASK; 159 tlen = MIN(PAGE_SIZE - offset, len); 160 161 VM_OBJECT_WLOCK(obj); 162 163 /* 164 * Read I/O without either a corresponding resident page or swap 165 * page: use zero_region. This is intended to avoid instantiating 166 * pages on read from a sparse region. 167 */ 168 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 169 !vm_pager_has_page(obj, idx, NULL, NULL)) { 170 VM_OBJECT_WUNLOCK(obj); 171 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 172 } 173 174 /* 175 * Parallel reads of the page content from disk are prevented 176 * by exclusive busy. 177 * 178 * Although the tmpfs vnode lock is held here, it is 179 * nonetheless safe to sleep waiting for a free page. The 180 * pageout daemon does not need to acquire the tmpfs vnode 181 * lock to page out tobj's pages because tobj is a OBJT_SWAP 182 * type object. 183 */ 184 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL); 185 if (m->valid != VM_PAGE_BITS_ALL) { 186 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 187 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL); 188 if (rv != VM_PAGER_OK) { 189 printf( 190 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 191 obj, idx, m->valid, rv); 192 vm_page_lock(m); 193 vm_page_free(m); 194 vm_page_unlock(m); 195 VM_OBJECT_WUNLOCK(obj); 196 return (EIO); 197 } 198 } else 199 vm_page_zero_invalid(m, TRUE); 200 } 201 vm_page_xunbusy(m); 202 vm_page_lock(m); 203 vm_page_hold(m); 204 if (m->queue == PQ_NONE) { 205 vm_page_deactivate(m); 206 } else { 207 /* Requeue to maintain LRU ordering. */ 208 vm_page_requeue(m); 209 } 210 vm_page_unlock(m); 211 VM_OBJECT_WUNLOCK(obj); 212 error = uiomove_fromphys(&m, offset, tlen, uio); 213 if (uio->uio_rw == UIO_WRITE && error == 0) { 214 VM_OBJECT_WLOCK(obj); 215 vm_page_dirty(m); 216 vm_pager_page_unswapped(m); 217 VM_OBJECT_WUNLOCK(obj); 218 } 219 vm_page_lock(m); 220 vm_page_unhold(m); 221 vm_page_unlock(m); 222 223 return (error); 224 } 225 226 int 227 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 228 { 229 ssize_t resid; 230 size_t len; 231 int error; 232 233 error = 0; 234 while ((resid = uio->uio_resid) > 0) { 235 if (obj_size <= uio->uio_offset) 236 break; 237 len = MIN(obj_size - uio->uio_offset, resid); 238 if (len == 0) 239 break; 240 error = uiomove_object_page(obj, len, uio); 241 if (error != 0 || resid == uio->uio_resid) 242 break; 243 } 244 return (error); 245 } 246 247 static int 248 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 249 { 250 struct shmfd *shmfd; 251 off_t foffset; 252 int error; 253 254 shmfd = fp->f_data; 255 foffset = foffset_lock(fp, 0); 256 error = 0; 257 switch (whence) { 258 case L_INCR: 259 if (foffset < 0 || 260 (offset > 0 && foffset > OFF_MAX - offset)) { 261 error = EOVERFLOW; 262 break; 263 } 264 offset += foffset; 265 break; 266 case L_XTND: 267 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 268 error = EOVERFLOW; 269 break; 270 } 271 offset += shmfd->shm_size; 272 break; 273 case L_SET: 274 break; 275 default: 276 error = EINVAL; 277 } 278 if (error == 0) { 279 if (offset < 0 || offset > shmfd->shm_size) 280 error = EINVAL; 281 else 282 td->td_uretoff.tdu_off = offset; 283 } 284 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 285 return (error); 286 } 287 288 static int 289 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 290 int flags, struct thread *td) 291 { 292 struct shmfd *shmfd; 293 void *rl_cookie; 294 int error; 295 296 shmfd = fp->f_data; 297 foffset_lock_uio(fp, uio, flags); 298 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 299 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 300 #ifdef MAC 301 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 302 if (error) 303 return (error); 304 #endif 305 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 306 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 307 foffset_unlock_uio(fp, uio, flags); 308 return (error); 309 } 310 311 static int 312 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 313 int flags, struct thread *td) 314 { 315 struct shmfd *shmfd; 316 void *rl_cookie; 317 int error; 318 319 shmfd = fp->f_data; 320 #ifdef MAC 321 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 322 if (error) 323 return (error); 324 #endif 325 foffset_lock_uio(fp, uio, flags); 326 if ((flags & FOF_OFFSET) == 0) { 327 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 328 &shmfd->shm_mtx); 329 } else { 330 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 331 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 332 } 333 334 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 335 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 336 foffset_unlock_uio(fp, uio, flags); 337 return (error); 338 } 339 340 static int 341 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 342 struct thread *td) 343 { 344 struct shmfd *shmfd; 345 #ifdef MAC 346 int error; 347 #endif 348 349 shmfd = fp->f_data; 350 #ifdef MAC 351 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 352 if (error) 353 return (error); 354 #endif 355 return (shm_dotruncate(shmfd, length)); 356 } 357 358 static int 359 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 360 struct thread *td) 361 { 362 struct shmfd *shmfd; 363 #ifdef MAC 364 int error; 365 #endif 366 367 shmfd = fp->f_data; 368 369 #ifdef MAC 370 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 371 if (error) 372 return (error); 373 #endif 374 375 /* 376 * Attempt to return sanish values for fstat() on a memory file 377 * descriptor. 378 */ 379 bzero(sb, sizeof(*sb)); 380 sb->st_blksize = PAGE_SIZE; 381 sb->st_size = shmfd->shm_size; 382 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 383 mtx_lock(&shm_timestamp_lock); 384 sb->st_atim = shmfd->shm_atime; 385 sb->st_ctim = shmfd->shm_ctime; 386 sb->st_mtim = shmfd->shm_mtime; 387 sb->st_birthtim = shmfd->shm_birthtime; 388 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 389 sb->st_uid = shmfd->shm_uid; 390 sb->st_gid = shmfd->shm_gid; 391 mtx_unlock(&shm_timestamp_lock); 392 sb->st_dev = shm_dev_ino; 393 sb->st_ino = shmfd->shm_ino; 394 395 return (0); 396 } 397 398 static int 399 shm_close(struct file *fp, struct thread *td) 400 { 401 struct shmfd *shmfd; 402 403 shmfd = fp->f_data; 404 fp->f_data = NULL; 405 shm_drop(shmfd); 406 407 return (0); 408 } 409 410 int 411 shm_dotruncate(struct shmfd *shmfd, off_t length) 412 { 413 vm_object_t object; 414 vm_page_t m; 415 vm_pindex_t idx, nobjsize; 416 vm_ooffset_t delta; 417 int base, rv; 418 419 object = shmfd->shm_object; 420 VM_OBJECT_WLOCK(object); 421 if (length == shmfd->shm_size) { 422 VM_OBJECT_WUNLOCK(object); 423 return (0); 424 } 425 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 426 427 /* Are we shrinking? If so, trim the end. */ 428 if (length < shmfd->shm_size) { 429 /* 430 * Disallow any requests to shrink the size if this 431 * object is mapped into the kernel. 432 */ 433 if (shmfd->shm_kmappings > 0) { 434 VM_OBJECT_WUNLOCK(object); 435 return (EBUSY); 436 } 437 438 /* 439 * Zero the truncated part of the last page. 440 */ 441 base = length & PAGE_MASK; 442 if (base != 0) { 443 idx = OFF_TO_IDX(length); 444 retry: 445 m = vm_page_lookup(object, idx); 446 if (m != NULL) { 447 if (vm_page_sleep_if_busy(m, "shmtrc")) 448 goto retry; 449 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 450 m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 451 if (m == NULL) { 452 VM_OBJECT_WUNLOCK(object); 453 VM_WAIT; 454 VM_OBJECT_WLOCK(object); 455 goto retry; 456 } else if (m->valid != VM_PAGE_BITS_ALL) 457 rv = vm_pager_get_pages(object, &m, 1, 458 NULL, NULL); 459 else 460 /* A cached page was reactivated. */ 461 rv = VM_PAGER_OK; 462 vm_page_lock(m); 463 if (rv == VM_PAGER_OK) { 464 vm_page_deactivate(m); 465 vm_page_unlock(m); 466 vm_page_xunbusy(m); 467 } else { 468 vm_page_free(m); 469 vm_page_unlock(m); 470 VM_OBJECT_WUNLOCK(object); 471 return (EIO); 472 } 473 } 474 if (m != NULL) { 475 pmap_zero_page_area(m, base, PAGE_SIZE - base); 476 KASSERT(m->valid == VM_PAGE_BITS_ALL, 477 ("shm_dotruncate: page %p is invalid", m)); 478 vm_page_dirty(m); 479 vm_pager_page_unswapped(m); 480 } 481 } 482 delta = ptoa(object->size - nobjsize); 483 484 /* Toss in memory pages. */ 485 if (nobjsize < object->size) 486 vm_object_page_remove(object, nobjsize, object->size, 487 0); 488 489 /* Toss pages from swap. */ 490 if (object->type == OBJT_SWAP) 491 swap_pager_freespace(object, nobjsize, delta); 492 493 /* Free the swap accounted for shm */ 494 swap_release_by_cred(delta, object->cred); 495 object->charge -= delta; 496 } else { 497 /* Attempt to reserve the swap */ 498 delta = ptoa(nobjsize - object->size); 499 if (!swap_reserve_by_cred(delta, object->cred)) { 500 VM_OBJECT_WUNLOCK(object); 501 return (ENOMEM); 502 } 503 object->charge += delta; 504 } 505 shmfd->shm_size = length; 506 mtx_lock(&shm_timestamp_lock); 507 vfs_timestamp(&shmfd->shm_ctime); 508 shmfd->shm_mtime = shmfd->shm_ctime; 509 mtx_unlock(&shm_timestamp_lock); 510 object->size = nobjsize; 511 VM_OBJECT_WUNLOCK(object); 512 return (0); 513 } 514 515 /* 516 * shmfd object management including creation and reference counting 517 * routines. 518 */ 519 struct shmfd * 520 shm_alloc(struct ucred *ucred, mode_t mode) 521 { 522 struct shmfd *shmfd; 523 int ino; 524 525 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 526 shmfd->shm_size = 0; 527 shmfd->shm_uid = ucred->cr_uid; 528 shmfd->shm_gid = ucred->cr_gid; 529 shmfd->shm_mode = mode; 530 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 531 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 532 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 533 shmfd->shm_object->pg_color = 0; 534 VM_OBJECT_WLOCK(shmfd->shm_object); 535 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 536 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 537 VM_OBJECT_WUNLOCK(shmfd->shm_object); 538 vfs_timestamp(&shmfd->shm_birthtime); 539 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 540 shmfd->shm_birthtime; 541 ino = alloc_unr(shm_ino_unr); 542 if (ino == -1) 543 shmfd->shm_ino = 0; 544 else 545 shmfd->shm_ino = ino; 546 refcount_init(&shmfd->shm_refs, 1); 547 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 548 rangelock_init(&shmfd->shm_rl); 549 #ifdef MAC 550 mac_posixshm_init(shmfd); 551 mac_posixshm_create(ucred, shmfd); 552 #endif 553 554 return (shmfd); 555 } 556 557 struct shmfd * 558 shm_hold(struct shmfd *shmfd) 559 { 560 561 refcount_acquire(&shmfd->shm_refs); 562 return (shmfd); 563 } 564 565 void 566 shm_drop(struct shmfd *shmfd) 567 { 568 569 if (refcount_release(&shmfd->shm_refs)) { 570 #ifdef MAC 571 mac_posixshm_destroy(shmfd); 572 #endif 573 rangelock_destroy(&shmfd->shm_rl); 574 mtx_destroy(&shmfd->shm_mtx); 575 vm_object_deallocate(shmfd->shm_object); 576 if (shmfd->shm_ino != 0) 577 free_unr(shm_ino_unr, shmfd->shm_ino); 578 free(shmfd, M_SHMFD); 579 } 580 } 581 582 /* 583 * Determine if the credentials have sufficient permissions for a 584 * specified combination of FREAD and FWRITE. 585 */ 586 int 587 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 588 { 589 accmode_t accmode; 590 int error; 591 592 accmode = 0; 593 if (flags & FREAD) 594 accmode |= VREAD; 595 if (flags & FWRITE) 596 accmode |= VWRITE; 597 mtx_lock(&shm_timestamp_lock); 598 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 599 accmode, ucred, NULL); 600 mtx_unlock(&shm_timestamp_lock); 601 return (error); 602 } 603 604 /* 605 * Dictionary management. We maintain an in-kernel dictionary to map 606 * paths to shmfd objects. We use the FNV hash on the path to store 607 * the mappings in a hash table. 608 */ 609 static void 610 shm_init(void *arg) 611 { 612 613 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 614 sx_init(&shm_dict_lock, "shm dictionary"); 615 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 616 shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL); 617 KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized")); 618 shm_dev_ino = devfs_alloc_cdp_inode(); 619 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 620 } 621 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 622 623 static struct shmfd * 624 shm_lookup(char *path, Fnv32_t fnv) 625 { 626 struct shm_mapping *map; 627 628 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 629 if (map->sm_fnv != fnv) 630 continue; 631 if (strcmp(map->sm_path, path) == 0) 632 return (map->sm_shmfd); 633 } 634 635 return (NULL); 636 } 637 638 static void 639 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 640 { 641 struct shm_mapping *map; 642 643 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 644 map->sm_path = path; 645 map->sm_fnv = fnv; 646 map->sm_shmfd = shm_hold(shmfd); 647 shmfd->shm_path = path; 648 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 649 } 650 651 static int 652 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 653 { 654 struct shm_mapping *map; 655 int error; 656 657 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 658 if (map->sm_fnv != fnv) 659 continue; 660 if (strcmp(map->sm_path, path) == 0) { 661 #ifdef MAC 662 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 663 if (error) 664 return (error); 665 #endif 666 error = shm_access(map->sm_shmfd, ucred, 667 FREAD | FWRITE); 668 if (error) 669 return (error); 670 map->sm_shmfd->shm_path = NULL; 671 LIST_REMOVE(map, sm_link); 672 shm_drop(map->sm_shmfd); 673 free(map->sm_path, M_SHMFD); 674 free(map, M_SHMFD); 675 return (0); 676 } 677 } 678 679 return (ENOENT); 680 } 681 682 int 683 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 684 struct filecaps *fcaps) 685 { 686 struct filedesc *fdp; 687 struct shmfd *shmfd; 688 struct file *fp; 689 char *path; 690 Fnv32_t fnv; 691 mode_t cmode; 692 int fd, error; 693 694 #ifdef CAPABILITY_MODE 695 /* 696 * shm_open(2) is only allowed for anonymous objects. 697 */ 698 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 699 return (ECAPMODE); 700 #endif 701 702 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 703 return (EINVAL); 704 705 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 706 return (EINVAL); 707 708 fdp = td->td_proc->p_fd; 709 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 710 711 error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps); 712 if (error) 713 return (error); 714 715 /* A SHM_ANON path pointer creates an anonymous object. */ 716 if (userpath == SHM_ANON) { 717 /* A read-only anonymous object is pointless. */ 718 if ((flags & O_ACCMODE) == O_RDONLY) { 719 fdclose(td, fp, fd); 720 fdrop(fp, td); 721 return (EINVAL); 722 } 723 shmfd = shm_alloc(td->td_ucred, cmode); 724 } else { 725 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 726 error = copyinstr(userpath, path, MAXPATHLEN, NULL); 727 #ifdef KTRACE 728 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 729 ktrnamei(path); 730 #endif 731 /* Require paths to start with a '/' character. */ 732 if (error == 0 && path[0] != '/') 733 error = EINVAL; 734 if (error) { 735 fdclose(td, fp, fd); 736 fdrop(fp, td); 737 free(path, M_SHMFD); 738 return (error); 739 } 740 741 fnv = fnv_32_str(path, FNV1_32_INIT); 742 sx_xlock(&shm_dict_lock); 743 shmfd = shm_lookup(path, fnv); 744 if (shmfd == NULL) { 745 /* Object does not yet exist, create it if requested. */ 746 if (flags & O_CREAT) { 747 #ifdef MAC 748 error = mac_posixshm_check_create(td->td_ucred, 749 path); 750 if (error == 0) { 751 #endif 752 shmfd = shm_alloc(td->td_ucred, cmode); 753 shm_insert(path, fnv, shmfd); 754 #ifdef MAC 755 } 756 #endif 757 } else { 758 free(path, M_SHMFD); 759 error = ENOENT; 760 } 761 } else { 762 /* 763 * Object already exists, obtain a new 764 * reference if requested and permitted. 765 */ 766 free(path, M_SHMFD); 767 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 768 error = EEXIST; 769 else { 770 #ifdef MAC 771 error = mac_posixshm_check_open(td->td_ucred, 772 shmfd, FFLAGS(flags & O_ACCMODE)); 773 if (error == 0) 774 #endif 775 error = shm_access(shmfd, td->td_ucred, 776 FFLAGS(flags & O_ACCMODE)); 777 } 778 779 /* 780 * Truncate the file back to zero length if 781 * O_TRUNC was specified and the object was 782 * opened with read/write. 783 */ 784 if (error == 0 && 785 (flags & (O_ACCMODE | O_TRUNC)) == 786 (O_RDWR | O_TRUNC)) { 787 #ifdef MAC 788 error = mac_posixshm_check_truncate( 789 td->td_ucred, fp->f_cred, shmfd); 790 if (error == 0) 791 #endif 792 shm_dotruncate(shmfd, 0); 793 } 794 if (error == 0) 795 shm_hold(shmfd); 796 } 797 sx_xunlock(&shm_dict_lock); 798 799 if (error) { 800 fdclose(td, fp, fd); 801 fdrop(fp, td); 802 return (error); 803 } 804 } 805 806 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 807 808 td->td_retval[0] = fd; 809 fdrop(fp, td); 810 811 return (0); 812 } 813 814 /* System calls. */ 815 int 816 sys_shm_open(struct thread *td, struct shm_open_args *uap) 817 { 818 819 return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL)); 820 } 821 822 int 823 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 824 { 825 char *path; 826 Fnv32_t fnv; 827 int error; 828 829 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 830 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 831 if (error) { 832 free(path, M_TEMP); 833 return (error); 834 } 835 #ifdef KTRACE 836 if (KTRPOINT(curthread, KTR_NAMEI)) 837 ktrnamei(path); 838 #endif 839 fnv = fnv_32_str(path, FNV1_32_INIT); 840 sx_xlock(&shm_dict_lock); 841 error = shm_remove(path, fnv, td->td_ucred); 842 sx_xunlock(&shm_dict_lock); 843 free(path, M_TEMP); 844 845 return (error); 846 } 847 848 int 849 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 850 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 851 vm_ooffset_t foff, struct thread *td) 852 { 853 struct shmfd *shmfd; 854 vm_prot_t maxprot; 855 int error; 856 857 shmfd = fp->f_data; 858 maxprot = VM_PROT_NONE; 859 860 /* FREAD should always be set. */ 861 if ((fp->f_flag & FREAD) != 0) 862 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 863 if ((fp->f_flag & FWRITE) != 0) 864 maxprot |= VM_PROT_WRITE; 865 866 /* Don't permit shared writable mappings on read-only descriptors. */ 867 if ((flags & MAP_SHARED) != 0 && 868 (maxprot & VM_PROT_WRITE) == 0 && 869 (prot & VM_PROT_WRITE) != 0) 870 return (EACCES); 871 maxprot &= cap_maxprot; 872 873 #ifdef MAC 874 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 875 if (error != 0) 876 return (error); 877 #endif 878 879 /* 880 * XXXRW: This validation is probably insufficient, and subject to 881 * sign errors. It should be fixed. 882 */ 883 if (foff >= shmfd->shm_size || 884 foff + objsize > round_page(shmfd->shm_size)) 885 return (EINVAL); 886 887 mtx_lock(&shm_timestamp_lock); 888 vfs_timestamp(&shmfd->shm_atime); 889 mtx_unlock(&shm_timestamp_lock); 890 vm_object_reference(shmfd->shm_object); 891 892 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 893 shmfd->shm_object, foff, FALSE, td); 894 if (error != 0) 895 vm_object_deallocate(shmfd->shm_object); 896 return (0); 897 } 898 899 static int 900 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 901 struct thread *td) 902 { 903 struct shmfd *shmfd; 904 int error; 905 906 error = 0; 907 shmfd = fp->f_data; 908 mtx_lock(&shm_timestamp_lock); 909 /* 910 * SUSv4 says that x bits of permission need not be affected. 911 * Be consistent with our shm_open there. 912 */ 913 #ifdef MAC 914 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 915 if (error != 0) 916 goto out; 917 #endif 918 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 919 shmfd->shm_gid, VADMIN, active_cred, NULL); 920 if (error != 0) 921 goto out; 922 shmfd->shm_mode = mode & ACCESSPERMS; 923 out: 924 mtx_unlock(&shm_timestamp_lock); 925 return (error); 926 } 927 928 static int 929 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 930 struct thread *td) 931 { 932 struct shmfd *shmfd; 933 int error; 934 935 error = 0; 936 shmfd = fp->f_data; 937 mtx_lock(&shm_timestamp_lock); 938 #ifdef MAC 939 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 940 if (error != 0) 941 goto out; 942 #endif 943 if (uid == (uid_t)-1) 944 uid = shmfd->shm_uid; 945 if (gid == (gid_t)-1) 946 gid = shmfd->shm_gid; 947 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 948 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 949 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 950 goto out; 951 shmfd->shm_uid = uid; 952 shmfd->shm_gid = gid; 953 out: 954 mtx_unlock(&shm_timestamp_lock); 955 return (error); 956 } 957 958 /* 959 * Helper routines to allow the backing object of a shared memory file 960 * descriptor to be mapped in the kernel. 961 */ 962 int 963 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 964 { 965 struct shmfd *shmfd; 966 vm_offset_t kva, ofs; 967 vm_object_t obj; 968 int rv; 969 970 if (fp->f_type != DTYPE_SHM) 971 return (EINVAL); 972 shmfd = fp->f_data; 973 obj = shmfd->shm_object; 974 VM_OBJECT_WLOCK(obj); 975 /* 976 * XXXRW: This validation is probably insufficient, and subject to 977 * sign errors. It should be fixed. 978 */ 979 if (offset >= shmfd->shm_size || 980 offset + size > round_page(shmfd->shm_size)) { 981 VM_OBJECT_WUNLOCK(obj); 982 return (EINVAL); 983 } 984 985 shmfd->shm_kmappings++; 986 vm_object_reference_locked(obj); 987 VM_OBJECT_WUNLOCK(obj); 988 989 /* Map the object into the kernel_map and wire it. */ 990 kva = vm_map_min(kernel_map); 991 ofs = offset & PAGE_MASK; 992 offset = trunc_page(offset); 993 size = round_page(size + ofs); 994 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 995 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 996 VM_PROT_READ | VM_PROT_WRITE, 0); 997 if (rv == KERN_SUCCESS) { 998 rv = vm_map_wire(kernel_map, kva, kva + size, 999 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1000 if (rv == KERN_SUCCESS) { 1001 *memp = (void *)(kva + ofs); 1002 return (0); 1003 } 1004 vm_map_remove(kernel_map, kva, kva + size); 1005 } else 1006 vm_object_deallocate(obj); 1007 1008 /* On failure, drop our mapping reference. */ 1009 VM_OBJECT_WLOCK(obj); 1010 shmfd->shm_kmappings--; 1011 VM_OBJECT_WUNLOCK(obj); 1012 1013 return (vm_mmap_to_errno(rv)); 1014 } 1015 1016 /* 1017 * We require the caller to unmap the entire entry. This allows us to 1018 * safely decrement shm_kmappings when a mapping is removed. 1019 */ 1020 int 1021 shm_unmap(struct file *fp, void *mem, size_t size) 1022 { 1023 struct shmfd *shmfd; 1024 vm_map_entry_t entry; 1025 vm_offset_t kva, ofs; 1026 vm_object_t obj; 1027 vm_pindex_t pindex; 1028 vm_prot_t prot; 1029 boolean_t wired; 1030 vm_map_t map; 1031 int rv; 1032 1033 if (fp->f_type != DTYPE_SHM) 1034 return (EINVAL); 1035 shmfd = fp->f_data; 1036 kva = (vm_offset_t)mem; 1037 ofs = kva & PAGE_MASK; 1038 kva = trunc_page(kva); 1039 size = round_page(size + ofs); 1040 map = kernel_map; 1041 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1042 &obj, &pindex, &prot, &wired); 1043 if (rv != KERN_SUCCESS) 1044 return (EINVAL); 1045 if (entry->start != kva || entry->end != kva + size) { 1046 vm_map_lookup_done(map, entry); 1047 return (EINVAL); 1048 } 1049 vm_map_lookup_done(map, entry); 1050 if (obj != shmfd->shm_object) 1051 return (EINVAL); 1052 vm_map_remove(map, kva, kva + size); 1053 VM_OBJECT_WLOCK(obj); 1054 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1055 shmfd->shm_kmappings--; 1056 VM_OBJECT_WUNLOCK(obj); 1057 return (0); 1058 } 1059 1060 static int 1061 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1062 { 1063 struct shmfd *shmfd; 1064 1065 kif->kf_type = KF_TYPE_SHM; 1066 shmfd = fp->f_data; 1067 1068 mtx_lock(&shm_timestamp_lock); 1069 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 1070 mtx_unlock(&shm_timestamp_lock); 1071 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1072 if (shmfd->shm_path != NULL) { 1073 sx_slock(&shm_dict_lock); 1074 if (shmfd->shm_path != NULL) 1075 strlcpy(kif->kf_path, shmfd->shm_path, 1076 sizeof(kif->kf_path)); 1077 sx_sunlock(&shm_dict_lock); 1078 } 1079 return (0); 1080 } 1081