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