1 /*- 2 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 3 * All rights reserved. 4 * 5 * Portions of this software were developed by BAE Systems, the University of 6 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 7 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 8 * Computing (TC) research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * Support for shared swap-backed anonymous memory objects via 34 * shm_open(2) and shm_unlink(2). While most of the implementation is 35 * here, vm_mmap.c contains mapping logic changes. 36 * 37 * TODO: 38 * 39 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) 40 * and ipcrm(1) be expanded or should new tools to manage both POSIX 41 * kernel semaphores and POSIX shared memory be written? 42 * 43 * (2) Add support for this file type to fstat(1). 44 * 45 * (3) Resource limits? Does this need its own resource limits or are the 46 * existing limits in mmap(2) sufficient? 47 */ 48 49 #include <sys/cdefs.h> 50 __FBSDID("$FreeBSD$"); 51 52 #include "opt_capsicum.h" 53 #include "opt_ktrace.h" 54 55 #include <sys/param.h> 56 #include <sys/capsicum.h> 57 #include <sys/conf.h> 58 #include <sys/fcntl.h> 59 #include <sys/file.h> 60 #include <sys/filedesc.h> 61 #include <sys/fnv_hash.h> 62 #include <sys/kernel.h> 63 #include <sys/uio.h> 64 #include <sys/signal.h> 65 #include <sys/jail.h> 66 #include <sys/ktrace.h> 67 #include <sys/lock.h> 68 #include <sys/malloc.h> 69 #include <sys/mman.h> 70 #include <sys/mutex.h> 71 #include <sys/priv.h> 72 #include <sys/proc.h> 73 #include <sys/refcount.h> 74 #include <sys/resourcevar.h> 75 #include <sys/rwlock.h> 76 #include <sys/stat.h> 77 #include <sys/syscallsubr.h> 78 #include <sys/sysctl.h> 79 #include <sys/sysproto.h> 80 #include <sys/systm.h> 81 #include <sys/sx.h> 82 #include <sys/time.h> 83 #include <sys/vnode.h> 84 #include <sys/unistd.h> 85 #include <sys/user.h> 86 87 #include <security/audit/audit.h> 88 #include <security/mac/mac_framework.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_extern.h> 94 #include <vm/vm_map.h> 95 #include <vm/vm_kern.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_page.h> 98 #include <vm/vm_pageout.h> 99 #include <vm/vm_pager.h> 100 #include <vm/swap_pager.h> 101 102 struct shm_mapping { 103 char *sm_path; 104 Fnv32_t sm_fnv; 105 struct shmfd *sm_shmfd; 106 LIST_ENTRY(shm_mapping) sm_link; 107 }; 108 109 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 110 static LIST_HEAD(, shm_mapping) *shm_dictionary; 111 static struct sx shm_dict_lock; 112 static struct mtx shm_timestamp_lock; 113 static u_long shm_hash; 114 static struct unrhdr *shm_ino_unr; 115 static dev_t shm_dev_ino; 116 117 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 118 119 static void shm_init(void *arg); 120 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 121 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 122 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 123 124 static fo_rdwr_t shm_read; 125 static fo_rdwr_t shm_write; 126 static fo_truncate_t shm_truncate; 127 static fo_stat_t shm_stat; 128 static fo_close_t shm_close; 129 static fo_chmod_t shm_chmod; 130 static fo_chown_t shm_chown; 131 static fo_seek_t shm_seek; 132 static fo_fill_kinfo_t shm_fill_kinfo; 133 static fo_mmap_t shm_mmap; 134 135 /* File descriptor operations. */ 136 struct fileops shm_ops = { 137 .fo_read = shm_read, 138 .fo_write = shm_write, 139 .fo_truncate = shm_truncate, 140 .fo_ioctl = invfo_ioctl, 141 .fo_poll = invfo_poll, 142 .fo_kqfilter = invfo_kqfilter, 143 .fo_stat = shm_stat, 144 .fo_close = shm_close, 145 .fo_chmod = shm_chmod, 146 .fo_chown = shm_chown, 147 .fo_sendfile = vn_sendfile, 148 .fo_seek = shm_seek, 149 .fo_fill_kinfo = shm_fill_kinfo, 150 .fo_mmap = shm_mmap, 151 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 152 }; 153 154 FEATURE(posix_shm, "POSIX shared memory"); 155 156 static int 157 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 158 { 159 vm_page_t m; 160 vm_pindex_t idx; 161 size_t tlen; 162 int error, offset, rv; 163 164 idx = OFF_TO_IDX(uio->uio_offset); 165 offset = uio->uio_offset & PAGE_MASK; 166 tlen = MIN(PAGE_SIZE - offset, len); 167 168 VM_OBJECT_WLOCK(obj); 169 170 /* 171 * Read I/O without either a corresponding resident page or swap 172 * page: use zero_region. This is intended to avoid instantiating 173 * pages on read from a sparse region. 174 */ 175 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 176 !vm_pager_has_page(obj, idx, NULL, NULL)) { 177 VM_OBJECT_WUNLOCK(obj); 178 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 179 } 180 181 /* 182 * Parallel reads of the page content from disk are prevented 183 * by exclusive busy. 184 * 185 * Although the tmpfs vnode lock is held here, it is 186 * nonetheless safe to sleep waiting for a free page. The 187 * pageout daemon does not need to acquire the tmpfs vnode 188 * lock to page out tobj's pages because tobj is a OBJT_SWAP 189 * type object. 190 */ 191 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY); 192 if (m->valid != VM_PAGE_BITS_ALL) { 193 vm_page_xbusy(m); 194 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 195 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL); 196 if (rv != VM_PAGER_OK) { 197 printf( 198 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 199 obj, idx, m->valid, rv); 200 vm_page_lock(m); 201 vm_page_free(m); 202 vm_page_unlock(m); 203 VM_OBJECT_WUNLOCK(obj); 204 return (EIO); 205 } 206 } else 207 vm_page_zero_invalid(m, TRUE); 208 vm_page_xunbusy(m); 209 } 210 vm_page_lock(m); 211 vm_page_hold(m); 212 if (m->queue == PQ_NONE) { 213 vm_page_deactivate(m); 214 } else { 215 /* Requeue to maintain LRU ordering. */ 216 vm_page_requeue(m); 217 } 218 vm_page_unlock(m); 219 VM_OBJECT_WUNLOCK(obj); 220 error = uiomove_fromphys(&m, offset, tlen, uio); 221 if (uio->uio_rw == UIO_WRITE && error == 0) { 222 VM_OBJECT_WLOCK(obj); 223 vm_page_dirty(m); 224 vm_pager_page_unswapped(m); 225 VM_OBJECT_WUNLOCK(obj); 226 } 227 vm_page_lock(m); 228 vm_page_unhold(m); 229 vm_page_unlock(m); 230 231 return (error); 232 } 233 234 int 235 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 236 { 237 ssize_t resid; 238 size_t len; 239 int error; 240 241 error = 0; 242 while ((resid = uio->uio_resid) > 0) { 243 if (obj_size <= uio->uio_offset) 244 break; 245 len = MIN(obj_size - uio->uio_offset, resid); 246 if (len == 0) 247 break; 248 error = uiomove_object_page(obj, len, uio); 249 if (error != 0 || resid == uio->uio_resid) 250 break; 251 } 252 return (error); 253 } 254 255 static int 256 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 257 { 258 struct shmfd *shmfd; 259 off_t foffset; 260 int error; 261 262 shmfd = fp->f_data; 263 foffset = foffset_lock(fp, 0); 264 error = 0; 265 switch (whence) { 266 case L_INCR: 267 if (foffset < 0 || 268 (offset > 0 && foffset > OFF_MAX - offset)) { 269 error = EOVERFLOW; 270 break; 271 } 272 offset += foffset; 273 break; 274 case L_XTND: 275 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 276 error = EOVERFLOW; 277 break; 278 } 279 offset += shmfd->shm_size; 280 break; 281 case L_SET: 282 break; 283 default: 284 error = EINVAL; 285 } 286 if (error == 0) { 287 if (offset < 0 || offset > shmfd->shm_size) 288 error = EINVAL; 289 else 290 td->td_uretoff.tdu_off = offset; 291 } 292 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 293 return (error); 294 } 295 296 static int 297 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 298 int flags, struct thread *td) 299 { 300 struct shmfd *shmfd; 301 void *rl_cookie; 302 int error; 303 304 shmfd = fp->f_data; 305 #ifdef MAC 306 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 307 if (error) 308 return (error); 309 #endif 310 foffset_lock_uio(fp, uio, flags); 311 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 312 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 313 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 314 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 315 foffset_unlock_uio(fp, uio, flags); 316 return (error); 317 } 318 319 static int 320 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 321 int flags, struct thread *td) 322 { 323 struct shmfd *shmfd; 324 void *rl_cookie; 325 int error; 326 327 shmfd = fp->f_data; 328 #ifdef MAC 329 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 330 if (error) 331 return (error); 332 #endif 333 foffset_lock_uio(fp, uio, flags); 334 if ((flags & FOF_OFFSET) == 0) { 335 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 336 &shmfd->shm_mtx); 337 } else { 338 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 339 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 340 } 341 342 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 343 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 344 foffset_unlock_uio(fp, uio, flags); 345 return (error); 346 } 347 348 static int 349 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 350 struct thread *td) 351 { 352 struct shmfd *shmfd; 353 #ifdef MAC 354 int error; 355 #endif 356 357 shmfd = fp->f_data; 358 #ifdef MAC 359 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 360 if (error) 361 return (error); 362 #endif 363 return (shm_dotruncate(shmfd, length)); 364 } 365 366 static int 367 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 368 struct thread *td) 369 { 370 struct shmfd *shmfd; 371 #ifdef MAC 372 int error; 373 #endif 374 375 shmfd = fp->f_data; 376 377 #ifdef MAC 378 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 379 if (error) 380 return (error); 381 #endif 382 383 /* 384 * Attempt to return sanish values for fstat() on a memory file 385 * descriptor. 386 */ 387 bzero(sb, sizeof(*sb)); 388 sb->st_blksize = PAGE_SIZE; 389 sb->st_size = shmfd->shm_size; 390 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 391 mtx_lock(&shm_timestamp_lock); 392 sb->st_atim = shmfd->shm_atime; 393 sb->st_ctim = shmfd->shm_ctime; 394 sb->st_mtim = shmfd->shm_mtime; 395 sb->st_birthtim = shmfd->shm_birthtime; 396 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 397 sb->st_uid = shmfd->shm_uid; 398 sb->st_gid = shmfd->shm_gid; 399 mtx_unlock(&shm_timestamp_lock); 400 sb->st_dev = shm_dev_ino; 401 sb->st_ino = shmfd->shm_ino; 402 403 return (0); 404 } 405 406 static int 407 shm_close(struct file *fp, struct thread *td) 408 { 409 struct shmfd *shmfd; 410 411 shmfd = fp->f_data; 412 fp->f_data = NULL; 413 shm_drop(shmfd); 414 415 return (0); 416 } 417 418 int 419 shm_dotruncate(struct shmfd *shmfd, off_t length) 420 { 421 vm_object_t object; 422 vm_page_t m; 423 vm_pindex_t idx, nobjsize; 424 vm_ooffset_t delta; 425 int base, rv; 426 427 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 428 object = shmfd->shm_object; 429 VM_OBJECT_WLOCK(object); 430 if (length == shmfd->shm_size) { 431 VM_OBJECT_WUNLOCK(object); 432 return (0); 433 } 434 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 435 436 /* Are we shrinking? If so, trim the end. */ 437 if (length < shmfd->shm_size) { 438 /* 439 * Disallow any requests to shrink the size if this 440 * object is mapped into the kernel. 441 */ 442 if (shmfd->shm_kmappings > 0) { 443 VM_OBJECT_WUNLOCK(object); 444 return (EBUSY); 445 } 446 447 /* 448 * Zero the truncated part of the last page. 449 */ 450 base = length & PAGE_MASK; 451 if (base != 0) { 452 idx = OFF_TO_IDX(length); 453 retry: 454 m = vm_page_lookup(object, idx); 455 if (m != NULL) { 456 if (vm_page_sleep_if_busy(m, "shmtrc")) 457 goto retry; 458 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 459 m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 460 if (m == NULL) { 461 VM_OBJECT_WUNLOCK(object); 462 VM_WAIT; 463 VM_OBJECT_WLOCK(object); 464 goto retry; 465 } 466 rv = vm_pager_get_pages(object, &m, 1, NULL, 467 NULL); 468 vm_page_lock(m); 469 if (rv == VM_PAGER_OK) { 470 /* 471 * Since the page was not resident, 472 * and therefore not recently 473 * accessed, immediately enqueue it 474 * for asynchronous laundering. The 475 * current operation is not regarded 476 * as an access. 477 */ 478 vm_page_launder(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 = IDX_TO_OFF(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 /* Try to reserve additional swap space. */ 512 delta = IDX_TO_OFF(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 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 struct shmfd * 572 shm_hold(struct shmfd *shmfd) 573 { 574 575 refcount_acquire(&shmfd->shm_refs); 576 return (shmfd); 577 } 578 579 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 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 int 697 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 698 struct filecaps *fcaps) 699 { 700 struct filedesc *fdp; 701 struct shmfd *shmfd; 702 struct file *fp; 703 char *path; 704 const char *pr_path; 705 size_t pr_pathlen; 706 Fnv32_t fnv; 707 mode_t cmode; 708 int fd, error; 709 710 #ifdef CAPABILITY_MODE 711 /* 712 * shm_open(2) is only allowed for anonymous objects. 713 */ 714 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 715 return (ECAPMODE); 716 #endif 717 718 AUDIT_ARG_FFLAGS(flags); 719 AUDIT_ARG_MODE(mode); 720 721 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 722 return (EINVAL); 723 724 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 725 return (EINVAL); 726 727 fdp = td->td_proc->p_fd; 728 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 729 730 error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps); 731 if (error) 732 return (error); 733 734 /* A SHM_ANON path pointer creates an anonymous object. */ 735 if (userpath == SHM_ANON) { 736 /* A read-only anonymous object is pointless. */ 737 if ((flags & O_ACCMODE) == O_RDONLY) { 738 fdclose(td, fp, fd); 739 fdrop(fp, td); 740 return (EINVAL); 741 } 742 shmfd = shm_alloc(td->td_ucred, cmode); 743 } else { 744 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 745 pr_path = td->td_ucred->cr_prison->pr_path; 746 747 /* Construct a full pathname for jailed callers. */ 748 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 749 : strlcpy(path, pr_path, MAXPATHLEN); 750 error = copyinstr(userpath, path + pr_pathlen, 751 MAXPATHLEN - pr_pathlen, NULL); 752 #ifdef KTRACE 753 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 754 ktrnamei(path); 755 #endif 756 /* Require paths to start with a '/' character. */ 757 if (error == 0 && path[pr_pathlen] != '/') 758 error = EINVAL; 759 if (error) { 760 fdclose(td, fp, fd); 761 fdrop(fp, td); 762 free(path, M_SHMFD); 763 return (error); 764 } 765 766 AUDIT_ARG_UPATH1_CANON(path); 767 fnv = fnv_32_str(path, FNV1_32_INIT); 768 sx_xlock(&shm_dict_lock); 769 shmfd = shm_lookup(path, fnv); 770 if (shmfd == NULL) { 771 /* Object does not yet exist, create it if requested. */ 772 if (flags & O_CREAT) { 773 #ifdef MAC 774 error = mac_posixshm_check_create(td->td_ucred, 775 path); 776 if (error == 0) { 777 #endif 778 shmfd = shm_alloc(td->td_ucred, cmode); 779 shm_insert(path, fnv, shmfd); 780 #ifdef MAC 781 } 782 #endif 783 } else { 784 free(path, M_SHMFD); 785 error = ENOENT; 786 } 787 } else { 788 /* 789 * Object already exists, obtain a new 790 * reference if requested and permitted. 791 */ 792 free(path, M_SHMFD); 793 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 794 error = EEXIST; 795 else { 796 #ifdef MAC 797 error = mac_posixshm_check_open(td->td_ucred, 798 shmfd, FFLAGS(flags & O_ACCMODE)); 799 if (error == 0) 800 #endif 801 error = shm_access(shmfd, td->td_ucred, 802 FFLAGS(flags & O_ACCMODE)); 803 } 804 805 /* 806 * Truncate the file back to zero length if 807 * O_TRUNC was specified and the object was 808 * opened with read/write. 809 */ 810 if (error == 0 && 811 (flags & (O_ACCMODE | O_TRUNC)) == 812 (O_RDWR | O_TRUNC)) { 813 #ifdef MAC 814 error = mac_posixshm_check_truncate( 815 td->td_ucred, fp->f_cred, shmfd); 816 if (error == 0) 817 #endif 818 shm_dotruncate(shmfd, 0); 819 } 820 if (error == 0) 821 shm_hold(shmfd); 822 } 823 sx_xunlock(&shm_dict_lock); 824 825 if (error) { 826 fdclose(td, fp, fd); 827 fdrop(fp, td); 828 return (error); 829 } 830 } 831 832 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 833 834 td->td_retval[0] = fd; 835 fdrop(fp, td); 836 837 return (0); 838 } 839 840 /* System calls. */ 841 int 842 sys_shm_open(struct thread *td, struct shm_open_args *uap) 843 { 844 845 return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL)); 846 } 847 848 int 849 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 850 { 851 char *path; 852 const char *pr_path; 853 size_t pr_pathlen; 854 Fnv32_t fnv; 855 int error; 856 857 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 858 pr_path = td->td_ucred->cr_prison->pr_path; 859 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 860 : strlcpy(path, pr_path, MAXPATHLEN); 861 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 862 NULL); 863 if (error) { 864 free(path, M_TEMP); 865 return (error); 866 } 867 #ifdef KTRACE 868 if (KTRPOINT(curthread, KTR_NAMEI)) 869 ktrnamei(path); 870 #endif 871 AUDIT_ARG_UPATH1_CANON(path); 872 fnv = fnv_32_str(path, FNV1_32_INIT); 873 sx_xlock(&shm_dict_lock); 874 error = shm_remove(path, fnv, td->td_ucred); 875 sx_xunlock(&shm_dict_lock); 876 free(path, M_TEMP); 877 878 return (error); 879 } 880 881 int 882 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 883 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 884 vm_ooffset_t foff, struct thread *td) 885 { 886 struct shmfd *shmfd; 887 vm_prot_t maxprot; 888 int error; 889 890 shmfd = fp->f_data; 891 maxprot = VM_PROT_NONE; 892 893 /* FREAD should always be set. */ 894 if ((fp->f_flag & FREAD) != 0) 895 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 896 if ((fp->f_flag & FWRITE) != 0) 897 maxprot |= VM_PROT_WRITE; 898 899 /* Don't permit shared writable mappings on read-only descriptors. */ 900 if ((flags & MAP_SHARED) != 0 && 901 (maxprot & VM_PROT_WRITE) == 0 && 902 (prot & VM_PROT_WRITE) != 0) 903 return (EACCES); 904 maxprot &= cap_maxprot; 905 906 /* See comment in vn_mmap(). */ 907 if ( 908 #ifdef _LP64 909 objsize > OFF_MAX || 910 #endif 911 foff < 0 || foff > OFF_MAX - objsize) 912 return (EINVAL); 913 914 #ifdef MAC 915 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 916 if (error != 0) 917 return (error); 918 #endif 919 920 mtx_lock(&shm_timestamp_lock); 921 vfs_timestamp(&shmfd->shm_atime); 922 mtx_unlock(&shm_timestamp_lock); 923 vm_object_reference(shmfd->shm_object); 924 925 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 926 shmfd->shm_object, foff, FALSE, td); 927 if (error != 0) 928 vm_object_deallocate(shmfd->shm_object); 929 return (error); 930 } 931 932 static int 933 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 934 struct thread *td) 935 { 936 struct shmfd *shmfd; 937 int error; 938 939 error = 0; 940 shmfd = fp->f_data; 941 mtx_lock(&shm_timestamp_lock); 942 /* 943 * SUSv4 says that x bits of permission need not be affected. 944 * Be consistent with our shm_open there. 945 */ 946 #ifdef MAC 947 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 948 if (error != 0) 949 goto out; 950 #endif 951 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 952 shmfd->shm_gid, VADMIN, active_cred, NULL); 953 if (error != 0) 954 goto out; 955 shmfd->shm_mode = mode & ACCESSPERMS; 956 out: 957 mtx_unlock(&shm_timestamp_lock); 958 return (error); 959 } 960 961 static int 962 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 963 struct thread *td) 964 { 965 struct shmfd *shmfd; 966 int error; 967 968 error = 0; 969 shmfd = fp->f_data; 970 mtx_lock(&shm_timestamp_lock); 971 #ifdef MAC 972 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 973 if (error != 0) 974 goto out; 975 #endif 976 if (uid == (uid_t)-1) 977 uid = shmfd->shm_uid; 978 if (gid == (gid_t)-1) 979 gid = shmfd->shm_gid; 980 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 981 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 982 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 983 goto out; 984 shmfd->shm_uid = uid; 985 shmfd->shm_gid = gid; 986 out: 987 mtx_unlock(&shm_timestamp_lock); 988 return (error); 989 } 990 991 /* 992 * Helper routines to allow the backing object of a shared memory file 993 * descriptor to be mapped in the kernel. 994 */ 995 int 996 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 997 { 998 struct shmfd *shmfd; 999 vm_offset_t kva, ofs; 1000 vm_object_t obj; 1001 int rv; 1002 1003 if (fp->f_type != DTYPE_SHM) 1004 return (EINVAL); 1005 shmfd = fp->f_data; 1006 obj = shmfd->shm_object; 1007 VM_OBJECT_WLOCK(obj); 1008 /* 1009 * XXXRW: This validation is probably insufficient, and subject to 1010 * sign errors. It should be fixed. 1011 */ 1012 if (offset >= shmfd->shm_size || 1013 offset + size > round_page(shmfd->shm_size)) { 1014 VM_OBJECT_WUNLOCK(obj); 1015 return (EINVAL); 1016 } 1017 1018 shmfd->shm_kmappings++; 1019 vm_object_reference_locked(obj); 1020 VM_OBJECT_WUNLOCK(obj); 1021 1022 /* Map the object into the kernel_map and wire it. */ 1023 kva = vm_map_min(kernel_map); 1024 ofs = offset & PAGE_MASK; 1025 offset = trunc_page(offset); 1026 size = round_page(size + ofs); 1027 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1028 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1029 VM_PROT_READ | VM_PROT_WRITE, 0); 1030 if (rv == KERN_SUCCESS) { 1031 rv = vm_map_wire(kernel_map, kva, kva + size, 1032 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1033 if (rv == KERN_SUCCESS) { 1034 *memp = (void *)(kva + ofs); 1035 return (0); 1036 } 1037 vm_map_remove(kernel_map, kva, kva + size); 1038 } else 1039 vm_object_deallocate(obj); 1040 1041 /* On failure, drop our mapping reference. */ 1042 VM_OBJECT_WLOCK(obj); 1043 shmfd->shm_kmappings--; 1044 VM_OBJECT_WUNLOCK(obj); 1045 1046 return (vm_mmap_to_errno(rv)); 1047 } 1048 1049 /* 1050 * We require the caller to unmap the entire entry. This allows us to 1051 * safely decrement shm_kmappings when a mapping is removed. 1052 */ 1053 int 1054 shm_unmap(struct file *fp, void *mem, size_t size) 1055 { 1056 struct shmfd *shmfd; 1057 vm_map_entry_t entry; 1058 vm_offset_t kva, ofs; 1059 vm_object_t obj; 1060 vm_pindex_t pindex; 1061 vm_prot_t prot; 1062 boolean_t wired; 1063 vm_map_t map; 1064 int rv; 1065 1066 if (fp->f_type != DTYPE_SHM) 1067 return (EINVAL); 1068 shmfd = fp->f_data; 1069 kva = (vm_offset_t)mem; 1070 ofs = kva & PAGE_MASK; 1071 kva = trunc_page(kva); 1072 size = round_page(size + ofs); 1073 map = kernel_map; 1074 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1075 &obj, &pindex, &prot, &wired); 1076 if (rv != KERN_SUCCESS) 1077 return (EINVAL); 1078 if (entry->start != kva || entry->end != kva + size) { 1079 vm_map_lookup_done(map, entry); 1080 return (EINVAL); 1081 } 1082 vm_map_lookup_done(map, entry); 1083 if (obj != shmfd->shm_object) 1084 return (EINVAL); 1085 vm_map_remove(map, kva, kva + size); 1086 VM_OBJECT_WLOCK(obj); 1087 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1088 shmfd->shm_kmappings--; 1089 VM_OBJECT_WUNLOCK(obj); 1090 return (0); 1091 } 1092 1093 static int 1094 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, struct filedesc *fdp) 1095 { 1096 const char *path, *pr_path; 1097 struct shmfd *shmfd; 1098 size_t pr_pathlen; 1099 1100 kif->kf_type = KF_TYPE_SHM; 1101 shmfd = fp->f_data; 1102 1103 mtx_lock(&shm_timestamp_lock); 1104 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 1105 mtx_unlock(&shm_timestamp_lock); 1106 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1107 if (shmfd->shm_path != NULL) { 1108 sx_slock(&shm_dict_lock); 1109 if (shmfd->shm_path != NULL) { 1110 path = shmfd->shm_path; 1111 pr_path = curthread->td_ucred->cr_prison->pr_path; 1112 if (strcmp(pr_path, "/") != 0) { 1113 /* Return the jail-rooted pathname. */ 1114 pr_pathlen = strlen(pr_path); 1115 if (strncmp(path, pr_path, pr_pathlen) == 0 && 1116 path[pr_pathlen] == '/') 1117 path += pr_pathlen; 1118 } 1119 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1120 } 1121 sx_sunlock(&shm_dict_lock); 1122 } 1123 return (0); 1124 } 1125