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 static fo_mmap_t shm_mmap; 131 132 /* File descriptor operations. */ 133 static struct fileops shm_ops = { 134 .fo_read = shm_read, 135 .fo_write = shm_write, 136 .fo_truncate = shm_truncate, 137 .fo_ioctl = invfo_ioctl, 138 .fo_poll = invfo_poll, 139 .fo_kqfilter = invfo_kqfilter, 140 .fo_stat = shm_stat, 141 .fo_close = shm_close, 142 .fo_chmod = shm_chmod, 143 .fo_chown = shm_chown, 144 .fo_sendfile = vn_sendfile, 145 .fo_seek = shm_seek, 146 .fo_fill_kinfo = shm_fill_kinfo, 147 .fo_mmap = shm_mmap, 148 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 149 }; 150 151 FEATURE(posix_shm, "POSIX shared memory"); 152 153 static int 154 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 155 { 156 vm_page_t m; 157 vm_pindex_t idx; 158 size_t tlen; 159 int error, offset, rv; 160 161 idx = OFF_TO_IDX(uio->uio_offset); 162 offset = uio->uio_offset & PAGE_MASK; 163 tlen = MIN(PAGE_SIZE - offset, len); 164 165 VM_OBJECT_WLOCK(obj); 166 167 /* 168 * Read I/O without either a corresponding resident page or swap 169 * page: use zero_region. This is intended to avoid instantiating 170 * pages on read from a sparse region. 171 */ 172 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 173 !vm_pager_has_page(obj, idx, NULL, NULL)) { 174 VM_OBJECT_WUNLOCK(obj); 175 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 176 } 177 178 /* 179 * Parallel reads of the page content from disk are prevented 180 * by exclusive busy. 181 * 182 * Although the tmpfs vnode lock is held here, it is 183 * nonetheless safe to sleep waiting for a free page. The 184 * pageout daemon does not need to acquire the tmpfs vnode 185 * lock to page out tobj's pages because tobj is a OBJT_SWAP 186 * type object. 187 */ 188 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL); 189 if (m->valid != VM_PAGE_BITS_ALL) { 190 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 191 rv = vm_pager_get_pages(obj, &m, 1, 0); 192 m = vm_page_lookup(obj, idx); 193 if (m == NULL) { 194 printf( 195 "uiomove_object: vm_obj %p idx %jd null lookup rv %d\n", 196 obj, idx, rv); 197 VM_OBJECT_WUNLOCK(obj); 198 return (EIO); 199 } 200 if (rv != VM_PAGER_OK) { 201 printf( 202 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 203 obj, idx, m->valid, rv); 204 vm_page_lock(m); 205 vm_page_free(m); 206 vm_page_unlock(m); 207 VM_OBJECT_WUNLOCK(obj); 208 return (EIO); 209 } 210 } else 211 vm_page_zero_invalid(m, TRUE); 212 } 213 vm_page_xunbusy(m); 214 vm_page_lock(m); 215 vm_page_hold(m); 216 if (m->queue == PQ_NONE) { 217 vm_page_deactivate(m); 218 } else { 219 /* Requeue to maintain LRU ordering. */ 220 vm_page_requeue(m); 221 } 222 vm_page_unlock(m); 223 VM_OBJECT_WUNLOCK(obj); 224 error = uiomove_fromphys(&m, offset, tlen, uio); 225 if (uio->uio_rw == UIO_WRITE && error == 0) { 226 VM_OBJECT_WLOCK(obj); 227 vm_page_dirty(m); 228 vm_pager_page_unswapped(m); 229 VM_OBJECT_WUNLOCK(obj); 230 } 231 vm_page_lock(m); 232 vm_page_unhold(m); 233 vm_page_unlock(m); 234 235 return (error); 236 } 237 238 int 239 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 240 { 241 ssize_t resid; 242 size_t len; 243 int error; 244 245 error = 0; 246 while ((resid = uio->uio_resid) > 0) { 247 if (obj_size <= uio->uio_offset) 248 break; 249 len = MIN(obj_size - uio->uio_offset, resid); 250 if (len == 0) 251 break; 252 error = uiomove_object_page(obj, len, uio); 253 if (error != 0 || resid == uio->uio_resid) 254 break; 255 } 256 return (error); 257 } 258 259 static int 260 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 261 { 262 struct shmfd *shmfd; 263 off_t foffset; 264 int error; 265 266 shmfd = fp->f_data; 267 foffset = foffset_lock(fp, 0); 268 error = 0; 269 switch (whence) { 270 case L_INCR: 271 if (foffset < 0 || 272 (offset > 0 && foffset > OFF_MAX - offset)) { 273 error = EOVERFLOW; 274 break; 275 } 276 offset += foffset; 277 break; 278 case L_XTND: 279 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 280 error = EOVERFLOW; 281 break; 282 } 283 offset += shmfd->shm_size; 284 break; 285 case L_SET: 286 break; 287 default: 288 error = EINVAL; 289 } 290 if (error == 0) { 291 if (offset < 0 || offset > shmfd->shm_size) 292 error = EINVAL; 293 else 294 td->td_uretoff.tdu_off = offset; 295 } 296 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 297 return (error); 298 } 299 300 static int 301 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 302 int flags, struct thread *td) 303 { 304 struct shmfd *shmfd; 305 void *rl_cookie; 306 int error; 307 308 shmfd = fp->f_data; 309 foffset_lock_uio(fp, uio, flags); 310 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 311 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 312 #ifdef MAC 313 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 314 if (error) 315 return (error); 316 #endif 317 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 318 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 319 foffset_unlock_uio(fp, uio, flags); 320 return (error); 321 } 322 323 static int 324 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 325 int flags, struct thread *td) 326 { 327 struct shmfd *shmfd; 328 void *rl_cookie; 329 int error; 330 331 shmfd = fp->f_data; 332 #ifdef MAC 333 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 334 if (error) 335 return (error); 336 #endif 337 foffset_lock_uio(fp, uio, flags); 338 if ((flags & FOF_OFFSET) == 0) { 339 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 340 &shmfd->shm_mtx); 341 } else { 342 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 343 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 344 } 345 346 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 347 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 348 foffset_unlock_uio(fp, uio, flags); 349 return (error); 350 } 351 352 static int 353 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 354 struct thread *td) 355 { 356 struct shmfd *shmfd; 357 #ifdef MAC 358 int error; 359 #endif 360 361 shmfd = fp->f_data; 362 #ifdef MAC 363 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 364 if (error) 365 return (error); 366 #endif 367 return (shm_dotruncate(shmfd, length)); 368 } 369 370 static int 371 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 372 struct thread *td) 373 { 374 struct shmfd *shmfd; 375 #ifdef MAC 376 int error; 377 #endif 378 379 shmfd = fp->f_data; 380 381 #ifdef MAC 382 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 383 if (error) 384 return (error); 385 #endif 386 387 /* 388 * Attempt to return sanish values for fstat() on a memory file 389 * descriptor. 390 */ 391 bzero(sb, sizeof(*sb)); 392 sb->st_blksize = PAGE_SIZE; 393 sb->st_size = shmfd->shm_size; 394 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 395 mtx_lock(&shm_timestamp_lock); 396 sb->st_atim = shmfd->shm_atime; 397 sb->st_ctim = shmfd->shm_ctime; 398 sb->st_mtim = shmfd->shm_mtime; 399 sb->st_birthtim = shmfd->shm_birthtime; 400 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 401 sb->st_uid = shmfd->shm_uid; 402 sb->st_gid = shmfd->shm_gid; 403 mtx_unlock(&shm_timestamp_lock); 404 sb->st_dev = shm_dev_ino; 405 sb->st_ino = shmfd->shm_ino; 406 407 return (0); 408 } 409 410 static int 411 shm_close(struct file *fp, struct thread *td) 412 { 413 struct shmfd *shmfd; 414 415 shmfd = fp->f_data; 416 fp->f_data = NULL; 417 shm_drop(shmfd); 418 419 return (0); 420 } 421 422 static int 423 shm_dotruncate(struct shmfd *shmfd, off_t length) 424 { 425 vm_object_t object; 426 vm_page_t m, ma[1]; 427 vm_pindex_t idx, nobjsize; 428 vm_ooffset_t delta; 429 int base, rv; 430 431 object = shmfd->shm_object; 432 VM_OBJECT_WLOCK(object); 433 if (length == shmfd->shm_size) { 434 VM_OBJECT_WUNLOCK(object); 435 return (0); 436 } 437 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 438 439 /* Are we shrinking? If so, trim the end. */ 440 if (length < shmfd->shm_size) { 441 /* 442 * Disallow any requests to shrink the size if this 443 * object is mapped into the kernel. 444 */ 445 if (shmfd->shm_kmappings > 0) { 446 VM_OBJECT_WUNLOCK(object); 447 return (EBUSY); 448 } 449 450 /* 451 * Zero the truncated part of the last page. 452 */ 453 base = length & PAGE_MASK; 454 if (base != 0) { 455 idx = OFF_TO_IDX(length); 456 retry: 457 m = vm_page_lookup(object, idx); 458 if (m != NULL) { 459 if (vm_page_sleep_if_busy(m, "shmtrc")) 460 goto retry; 461 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 462 m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 463 if (m == NULL) { 464 VM_OBJECT_WUNLOCK(object); 465 VM_WAIT; 466 VM_OBJECT_WLOCK(object); 467 goto retry; 468 } else if (m->valid != VM_PAGE_BITS_ALL) { 469 ma[0] = m; 470 rv = vm_pager_get_pages(object, ma, 1, 471 0); 472 m = vm_page_lookup(object, idx); 473 } else 474 /* A cached page was reactivated. */ 475 rv = VM_PAGER_OK; 476 vm_page_lock(m); 477 if (rv == VM_PAGER_OK) { 478 vm_page_deactivate(m); 479 vm_page_unlock(m); 480 vm_page_xunbusy(m); 481 } else { 482 vm_page_free(m); 483 vm_page_unlock(m); 484 VM_OBJECT_WUNLOCK(object); 485 return (EIO); 486 } 487 } 488 if (m != NULL) { 489 pmap_zero_page_area(m, base, PAGE_SIZE - base); 490 KASSERT(m->valid == VM_PAGE_BITS_ALL, 491 ("shm_dotruncate: page %p is invalid", m)); 492 vm_page_dirty(m); 493 vm_pager_page_unswapped(m); 494 } 495 } 496 delta = ptoa(object->size - nobjsize); 497 498 /* Toss in memory pages. */ 499 if (nobjsize < object->size) 500 vm_object_page_remove(object, nobjsize, object->size, 501 0); 502 503 /* Toss pages from swap. */ 504 if (object->type == OBJT_SWAP) 505 swap_pager_freespace(object, nobjsize, delta); 506 507 /* Free the swap accounted for shm */ 508 swap_release_by_cred(delta, object->cred); 509 object->charge -= delta; 510 } else { 511 /* Attempt to reserve the swap */ 512 delta = ptoa(nobjsize - object->size); 513 if (!swap_reserve_by_cred(delta, object->cred)) { 514 VM_OBJECT_WUNLOCK(object); 515 return (ENOMEM); 516 } 517 object->charge += delta; 518 } 519 shmfd->shm_size = length; 520 mtx_lock(&shm_timestamp_lock); 521 vfs_timestamp(&shmfd->shm_ctime); 522 shmfd->shm_mtime = shmfd->shm_ctime; 523 mtx_unlock(&shm_timestamp_lock); 524 object->size = nobjsize; 525 VM_OBJECT_WUNLOCK(object); 526 return (0); 527 } 528 529 /* 530 * shmfd object management including creation and reference counting 531 * routines. 532 */ 533 static struct shmfd * 534 shm_alloc(struct ucred *ucred, mode_t mode) 535 { 536 struct shmfd *shmfd; 537 int ino; 538 539 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 540 shmfd->shm_size = 0; 541 shmfd->shm_uid = ucred->cr_uid; 542 shmfd->shm_gid = ucred->cr_gid; 543 shmfd->shm_mode = mode; 544 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 545 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 546 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 547 shmfd->shm_object->pg_color = 0; 548 VM_OBJECT_WLOCK(shmfd->shm_object); 549 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 550 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 551 VM_OBJECT_WUNLOCK(shmfd->shm_object); 552 vfs_timestamp(&shmfd->shm_birthtime); 553 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 554 shmfd->shm_birthtime; 555 ino = alloc_unr(shm_ino_unr); 556 if (ino == -1) 557 shmfd->shm_ino = 0; 558 else 559 shmfd->shm_ino = ino; 560 refcount_init(&shmfd->shm_refs, 1); 561 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 562 rangelock_init(&shmfd->shm_rl); 563 #ifdef MAC 564 mac_posixshm_init(shmfd); 565 mac_posixshm_create(ucred, shmfd); 566 #endif 567 568 return (shmfd); 569 } 570 571 static struct shmfd * 572 shm_hold(struct shmfd *shmfd) 573 { 574 575 refcount_acquire(&shmfd->shm_refs); 576 return (shmfd); 577 } 578 579 static void 580 shm_drop(struct shmfd *shmfd) 581 { 582 583 if (refcount_release(&shmfd->shm_refs)) { 584 #ifdef MAC 585 mac_posixshm_destroy(shmfd); 586 #endif 587 rangelock_destroy(&shmfd->shm_rl); 588 mtx_destroy(&shmfd->shm_mtx); 589 vm_object_deallocate(shmfd->shm_object); 590 if (shmfd->shm_ino != 0) 591 free_unr(shm_ino_unr, shmfd->shm_ino); 592 free(shmfd, M_SHMFD); 593 } 594 } 595 596 /* 597 * Determine if the credentials have sufficient permissions for a 598 * specified combination of FREAD and FWRITE. 599 */ 600 static int 601 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 602 { 603 accmode_t accmode; 604 int error; 605 606 accmode = 0; 607 if (flags & FREAD) 608 accmode |= VREAD; 609 if (flags & FWRITE) 610 accmode |= VWRITE; 611 mtx_lock(&shm_timestamp_lock); 612 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 613 accmode, ucred, NULL); 614 mtx_unlock(&shm_timestamp_lock); 615 return (error); 616 } 617 618 /* 619 * Dictionary management. We maintain an in-kernel dictionary to map 620 * paths to shmfd objects. We use the FNV hash on the path to store 621 * the mappings in a hash table. 622 */ 623 static void 624 shm_init(void *arg) 625 { 626 627 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 628 sx_init(&shm_dict_lock, "shm dictionary"); 629 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 630 shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL); 631 KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized")); 632 shm_dev_ino = devfs_alloc_cdp_inode(); 633 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 634 } 635 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 636 637 static struct shmfd * 638 shm_lookup(char *path, Fnv32_t fnv) 639 { 640 struct shm_mapping *map; 641 642 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 643 if (map->sm_fnv != fnv) 644 continue; 645 if (strcmp(map->sm_path, path) == 0) 646 return (map->sm_shmfd); 647 } 648 649 return (NULL); 650 } 651 652 static void 653 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 654 { 655 struct shm_mapping *map; 656 657 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 658 map->sm_path = path; 659 map->sm_fnv = fnv; 660 map->sm_shmfd = shm_hold(shmfd); 661 shmfd->shm_path = path; 662 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 663 } 664 665 static int 666 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 667 { 668 struct shm_mapping *map; 669 int error; 670 671 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 672 if (map->sm_fnv != fnv) 673 continue; 674 if (strcmp(map->sm_path, path) == 0) { 675 #ifdef MAC 676 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 677 if (error) 678 return (error); 679 #endif 680 error = shm_access(map->sm_shmfd, ucred, 681 FREAD | FWRITE); 682 if (error) 683 return (error); 684 map->sm_shmfd->shm_path = NULL; 685 LIST_REMOVE(map, sm_link); 686 shm_drop(map->sm_shmfd); 687 free(map->sm_path, M_SHMFD); 688 free(map, M_SHMFD); 689 return (0); 690 } 691 } 692 693 return (ENOENT); 694 } 695 696 /* System calls. */ 697 int 698 sys_shm_open(struct thread *td, struct shm_open_args *uap) 699 { 700 struct filedesc *fdp; 701 struct shmfd *shmfd; 702 struct file *fp; 703 char *path; 704 Fnv32_t fnv; 705 mode_t cmode; 706 int fd, error; 707 708 #ifdef CAPABILITY_MODE 709 /* 710 * shm_open(2) is only allowed for anonymous objects. 711 */ 712 if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 713 return (ECAPMODE); 714 #endif 715 716 if ((uap->flags & O_ACCMODE) != O_RDONLY && 717 (uap->flags & O_ACCMODE) != O_RDWR) 718 return (EINVAL); 719 720 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 721 return (EINVAL); 722 723 fdp = td->td_proc->p_fd; 724 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 725 726 error = falloc(td, &fp, &fd, O_CLOEXEC); 727 if (error) 728 return (error); 729 730 /* A SHM_ANON path pointer creates an anonymous object. */ 731 if (uap->path == SHM_ANON) { 732 /* A read-only anonymous object is pointless. */ 733 if ((uap->flags & O_ACCMODE) == O_RDONLY) { 734 fdclose(td, fp, fd); 735 fdrop(fp, td); 736 return (EINVAL); 737 } 738 shmfd = shm_alloc(td->td_ucred, cmode); 739 } else { 740 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 741 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 742 #ifdef KTRACE 743 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 744 ktrnamei(path); 745 #endif 746 /* Require paths to start with a '/' character. */ 747 if (error == 0 && path[0] != '/') 748 error = EINVAL; 749 if (error) { 750 fdclose(td, fp, fd); 751 fdrop(fp, td); 752 free(path, M_SHMFD); 753 return (error); 754 } 755 756 fnv = fnv_32_str(path, FNV1_32_INIT); 757 sx_xlock(&shm_dict_lock); 758 shmfd = shm_lookup(path, fnv); 759 if (shmfd == NULL) { 760 /* Object does not yet exist, create it if requested. */ 761 if (uap->flags & O_CREAT) { 762 #ifdef MAC 763 error = mac_posixshm_check_create(td->td_ucred, 764 path); 765 if (error == 0) { 766 #endif 767 shmfd = shm_alloc(td->td_ucred, cmode); 768 shm_insert(path, fnv, shmfd); 769 #ifdef MAC 770 } 771 #endif 772 } else { 773 free(path, M_SHMFD); 774 error = ENOENT; 775 } 776 } else { 777 /* 778 * Object already exists, obtain a new 779 * reference if requested and permitted. 780 */ 781 free(path, M_SHMFD); 782 if ((uap->flags & (O_CREAT | O_EXCL)) == 783 (O_CREAT | O_EXCL)) 784 error = EEXIST; 785 else { 786 #ifdef MAC 787 error = mac_posixshm_check_open(td->td_ucred, 788 shmfd, FFLAGS(uap->flags & O_ACCMODE)); 789 if (error == 0) 790 #endif 791 error = shm_access(shmfd, td->td_ucred, 792 FFLAGS(uap->flags & O_ACCMODE)); 793 } 794 795 /* 796 * Truncate the file back to zero length if 797 * O_TRUNC was specified and the object was 798 * opened with read/write. 799 */ 800 if (error == 0 && 801 (uap->flags & (O_ACCMODE | O_TRUNC)) == 802 (O_RDWR | O_TRUNC)) { 803 #ifdef MAC 804 error = mac_posixshm_check_truncate( 805 td->td_ucred, fp->f_cred, shmfd); 806 if (error == 0) 807 #endif 808 shm_dotruncate(shmfd, 0); 809 } 810 if (error == 0) 811 shm_hold(shmfd); 812 } 813 sx_xunlock(&shm_dict_lock); 814 815 if (error) { 816 fdclose(td, fp, fd); 817 fdrop(fp, td); 818 return (error); 819 } 820 } 821 822 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 823 824 td->td_retval[0] = fd; 825 fdrop(fp, td); 826 827 return (0); 828 } 829 830 int 831 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 832 { 833 char *path; 834 Fnv32_t fnv; 835 int error; 836 837 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 838 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 839 if (error) { 840 free(path, M_TEMP); 841 return (error); 842 } 843 #ifdef KTRACE 844 if (KTRPOINT(curthread, KTR_NAMEI)) 845 ktrnamei(path); 846 #endif 847 fnv = fnv_32_str(path, FNV1_32_INIT); 848 sx_xlock(&shm_dict_lock); 849 error = shm_remove(path, fnv, td->td_ucred); 850 sx_xunlock(&shm_dict_lock); 851 free(path, M_TEMP); 852 853 return (error); 854 } 855 856 int 857 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 858 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 859 vm_ooffset_t foff, struct thread *td) 860 { 861 struct shmfd *shmfd; 862 vm_prot_t maxprot; 863 int error; 864 865 shmfd = fp->f_data; 866 maxprot = VM_PROT_NONE; 867 868 /* FREAD should always be set. */ 869 if ((fp->f_flag & FREAD) != 0) 870 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 871 if ((fp->f_flag & FWRITE) != 0) 872 maxprot |= VM_PROT_WRITE; 873 874 /* Don't permit shared writable mappings on read-only descriptors. */ 875 if ((flags & MAP_SHARED) != 0 && 876 (maxprot & VM_PROT_WRITE) == 0 && 877 (prot & VM_PROT_WRITE) != 0) 878 return (EACCES); 879 maxprot &= cap_maxprot; 880 881 #ifdef MAC 882 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 883 if (error != 0) 884 return (error); 885 #endif 886 887 /* 888 * XXXRW: This validation is probably insufficient, and subject to 889 * sign errors. It should be fixed. 890 */ 891 if (foff >= shmfd->shm_size || 892 foff + objsize > round_page(shmfd->shm_size)) 893 return (EINVAL); 894 895 mtx_lock(&shm_timestamp_lock); 896 vfs_timestamp(&shmfd->shm_atime); 897 mtx_unlock(&shm_timestamp_lock); 898 vm_object_reference(shmfd->shm_object); 899 900 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 901 shmfd->shm_object, foff, FALSE, td); 902 if (error != 0) 903 vm_object_deallocate(shmfd->shm_object); 904 return (0); 905 } 906 907 static int 908 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 909 struct thread *td) 910 { 911 struct shmfd *shmfd; 912 int error; 913 914 error = 0; 915 shmfd = fp->f_data; 916 mtx_lock(&shm_timestamp_lock); 917 /* 918 * SUSv4 says that x bits of permission need not be affected. 919 * Be consistent with our shm_open there. 920 */ 921 #ifdef MAC 922 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 923 if (error != 0) 924 goto out; 925 #endif 926 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 927 shmfd->shm_gid, VADMIN, active_cred, NULL); 928 if (error != 0) 929 goto out; 930 shmfd->shm_mode = mode & ACCESSPERMS; 931 out: 932 mtx_unlock(&shm_timestamp_lock); 933 return (error); 934 } 935 936 static int 937 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 938 struct thread *td) 939 { 940 struct shmfd *shmfd; 941 int error; 942 943 error = 0; 944 shmfd = fp->f_data; 945 mtx_lock(&shm_timestamp_lock); 946 #ifdef MAC 947 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 948 if (error != 0) 949 goto out; 950 #endif 951 if (uid == (uid_t)-1) 952 uid = shmfd->shm_uid; 953 if (gid == (gid_t)-1) 954 gid = shmfd->shm_gid; 955 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 956 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 957 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 958 goto out; 959 shmfd->shm_uid = uid; 960 shmfd->shm_gid = gid; 961 out: 962 mtx_unlock(&shm_timestamp_lock); 963 return (error); 964 } 965 966 /* 967 * Helper routines to allow the backing object of a shared memory file 968 * descriptor to be mapped in the kernel. 969 */ 970 int 971 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 972 { 973 struct shmfd *shmfd; 974 vm_offset_t kva, ofs; 975 vm_object_t obj; 976 int rv; 977 978 if (fp->f_type != DTYPE_SHM) 979 return (EINVAL); 980 shmfd = fp->f_data; 981 obj = shmfd->shm_object; 982 VM_OBJECT_WLOCK(obj); 983 /* 984 * XXXRW: This validation is probably insufficient, and subject to 985 * sign errors. It should be fixed. 986 */ 987 if (offset >= shmfd->shm_size || 988 offset + size > round_page(shmfd->shm_size)) { 989 VM_OBJECT_WUNLOCK(obj); 990 return (EINVAL); 991 } 992 993 shmfd->shm_kmappings++; 994 vm_object_reference_locked(obj); 995 VM_OBJECT_WUNLOCK(obj); 996 997 /* Map the object into the kernel_map and wire it. */ 998 kva = vm_map_min(kernel_map); 999 ofs = offset & PAGE_MASK; 1000 offset = trunc_page(offset); 1001 size = round_page(size + ofs); 1002 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1003 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1004 VM_PROT_READ | VM_PROT_WRITE, 0); 1005 if (rv == KERN_SUCCESS) { 1006 rv = vm_map_wire(kernel_map, kva, kva + size, 1007 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1008 if (rv == KERN_SUCCESS) { 1009 *memp = (void *)(kva + ofs); 1010 return (0); 1011 } 1012 vm_map_remove(kernel_map, kva, kva + size); 1013 } else 1014 vm_object_deallocate(obj); 1015 1016 /* On failure, drop our mapping reference. */ 1017 VM_OBJECT_WLOCK(obj); 1018 shmfd->shm_kmappings--; 1019 VM_OBJECT_WUNLOCK(obj); 1020 1021 return (vm_mmap_to_errno(rv)); 1022 } 1023 1024 /* 1025 * We require the caller to unmap the entire entry. This allows us to 1026 * safely decrement shm_kmappings when a mapping is removed. 1027 */ 1028 int 1029 shm_unmap(struct file *fp, void *mem, size_t size) 1030 { 1031 struct shmfd *shmfd; 1032 vm_map_entry_t entry; 1033 vm_offset_t kva, ofs; 1034 vm_object_t obj; 1035 vm_pindex_t pindex; 1036 vm_prot_t prot; 1037 boolean_t wired; 1038 vm_map_t map; 1039 int rv; 1040 1041 if (fp->f_type != DTYPE_SHM) 1042 return (EINVAL); 1043 shmfd = fp->f_data; 1044 kva = (vm_offset_t)mem; 1045 ofs = kva & PAGE_MASK; 1046 kva = trunc_page(kva); 1047 size = round_page(size + ofs); 1048 map = kernel_map; 1049 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1050 &obj, &pindex, &prot, &wired); 1051 if (rv != KERN_SUCCESS) 1052 return (EINVAL); 1053 if (entry->start != kva || entry->end != kva + size) { 1054 vm_map_lookup_done(map, entry); 1055 return (EINVAL); 1056 } 1057 vm_map_lookup_done(map, entry); 1058 if (obj != shmfd->shm_object) 1059 return (EINVAL); 1060 vm_map_remove(map, kva, kva + size); 1061 VM_OBJECT_WLOCK(obj); 1062 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1063 shmfd->shm_kmappings--; 1064 VM_OBJECT_WUNLOCK(obj); 1065 return (0); 1066 } 1067 1068 static int 1069 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1070 { 1071 struct shmfd *shmfd; 1072 1073 kif->kf_type = KF_TYPE_SHM; 1074 shmfd = fp->f_data; 1075 1076 mtx_lock(&shm_timestamp_lock); 1077 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 1078 mtx_unlock(&shm_timestamp_lock); 1079 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1080 if (shmfd->shm_path != NULL) { 1081 sx_slock(&shm_dict_lock); 1082 if (shmfd->shm_path != NULL) 1083 strlcpy(kif->kf_path, shmfd->shm_path, 1084 sizeof(kif->kf_path)); 1085 sx_sunlock(&shm_dict_lock); 1086 } 1087 return (0); 1088 } 1089