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