1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * Portions of this software were developed by BAE Systems, the University of 8 * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL 9 * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent 10 * Computing (TC) research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * Support for shared swap-backed anonymous memory objects via 36 * shm_open(2) and shm_unlink(2). While most of the implementation is 37 * here, vm_mmap.c contains mapping logic changes. 38 * 39 * posixshmcontrol(1) allows users to inspect the state of the memory 40 * objects. Per-uid swap resource limit controls total amount of 41 * memory that user can consume for anonymous objects, including 42 * shared. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include "opt_capsicum.h" 49 #include "opt_ktrace.h" 50 51 #include <sys/param.h> 52 #include <sys/capsicum.h> 53 #include <sys/conf.h> 54 #include <sys/fcntl.h> 55 #include <sys/file.h> 56 #include <sys/filedesc.h> 57 #include <sys/filio.h> 58 #include <sys/fnv_hash.h> 59 #include <sys/kernel.h> 60 #include <sys/limits.h> 61 #include <sys/uio.h> 62 #include <sys/signal.h> 63 #include <sys/jail.h> 64 #include <sys/ktrace.h> 65 #include <sys/lock.h> 66 #include <sys/malloc.h> 67 #include <sys/mman.h> 68 #include <sys/mutex.h> 69 #include <sys/priv.h> 70 #include <sys/proc.h> 71 #include <sys/refcount.h> 72 #include <sys/resourcevar.h> 73 #include <sys/rwlock.h> 74 #include <sys/sbuf.h> 75 #include <sys/stat.h> 76 #include <sys/syscallsubr.h> 77 #include <sys/sysctl.h> 78 #include <sys/sysproto.h> 79 #include <sys/systm.h> 80 #include <sys/sx.h> 81 #include <sys/time.h> 82 #include <sys/vnode.h> 83 #include <sys/unistd.h> 84 #include <sys/user.h> 85 86 #include <security/audit/audit.h> 87 #include <security/mac/mac_framework.h> 88 89 #include <vm/vm.h> 90 #include <vm/vm_param.h> 91 #include <vm/pmap.h> 92 #include <vm/vm_extern.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_kern.h> 95 #include <vm/vm_object.h> 96 #include <vm/vm_page.h> 97 #include <vm/vm_pageout.h> 98 #include <vm/vm_pager.h> 99 #include <vm/swap_pager.h> 100 101 struct shm_mapping { 102 char *sm_path; 103 Fnv32_t sm_fnv; 104 struct shmfd *sm_shmfd; 105 LIST_ENTRY(shm_mapping) sm_link; 106 }; 107 108 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 109 static LIST_HEAD(, shm_mapping) *shm_dictionary; 110 static struct sx shm_dict_lock; 111 static struct mtx shm_timestamp_lock; 112 static u_long shm_hash; 113 static struct unrhdr64 shm_ino_unr; 114 static dev_t shm_dev_ino; 115 116 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 117 118 static void shm_init(void *arg); 119 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 120 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 121 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 122 123 static fo_rdwr_t shm_read; 124 static fo_rdwr_t shm_write; 125 static fo_truncate_t shm_truncate; 126 static fo_ioctl_t shm_ioctl; 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 = shm_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 VM_ALLOC_WIRED); 193 if (m->valid != VM_PAGE_BITS_ALL) { 194 vm_page_xbusy(m); 195 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 196 rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL); 197 if (rv != VM_PAGER_OK) { 198 printf( 199 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 200 obj, idx, m->valid, rv); 201 vm_page_lock(m); 202 vm_page_unwire_noq(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 vm_page_xunbusy(m); 211 } 212 VM_OBJECT_WUNLOCK(obj); 213 error = uiomove_fromphys(&m, offset, tlen, uio); 214 if (uio->uio_rw == UIO_WRITE && error == 0) { 215 VM_OBJECT_WLOCK(obj); 216 vm_page_dirty(m); 217 vm_pager_page_unswapped(m); 218 VM_OBJECT_WUNLOCK(obj); 219 } 220 vm_page_lock(m); 221 vm_page_unwire(m, PQ_ACTIVE); 222 vm_page_unlock(m); 223 224 return (error); 225 } 226 227 int 228 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 229 { 230 ssize_t resid; 231 size_t len; 232 int error; 233 234 error = 0; 235 while ((resid = uio->uio_resid) > 0) { 236 if (obj_size <= uio->uio_offset) 237 break; 238 len = MIN(obj_size - uio->uio_offset, resid); 239 if (len == 0) 240 break; 241 error = uiomove_object_page(obj, len, uio); 242 if (error != 0 || resid == uio->uio_resid) 243 break; 244 } 245 return (error); 246 } 247 248 static int 249 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 250 { 251 struct shmfd *shmfd; 252 off_t foffset; 253 int error; 254 255 shmfd = fp->f_data; 256 foffset = foffset_lock(fp, 0); 257 error = 0; 258 switch (whence) { 259 case L_INCR: 260 if (foffset < 0 || 261 (offset > 0 && foffset > OFF_MAX - offset)) { 262 error = EOVERFLOW; 263 break; 264 } 265 offset += foffset; 266 break; 267 case L_XTND: 268 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 269 error = EOVERFLOW; 270 break; 271 } 272 offset += shmfd->shm_size; 273 break; 274 case L_SET: 275 break; 276 default: 277 error = EINVAL; 278 } 279 if (error == 0) { 280 if (offset < 0 || offset > shmfd->shm_size) 281 error = EINVAL; 282 else 283 td->td_uretoff.tdu_off = offset; 284 } 285 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 286 return (error); 287 } 288 289 static int 290 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 291 int flags, struct thread *td) 292 { 293 struct shmfd *shmfd; 294 void *rl_cookie; 295 int error; 296 297 shmfd = fp->f_data; 298 #ifdef MAC 299 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 300 if (error) 301 return (error); 302 #endif 303 foffset_lock_uio(fp, uio, flags); 304 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 305 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 306 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 307 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 308 foffset_unlock_uio(fp, uio, flags); 309 return (error); 310 } 311 312 static int 313 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 314 int flags, struct thread *td) 315 { 316 struct shmfd *shmfd; 317 void *rl_cookie; 318 int error; 319 320 shmfd = fp->f_data; 321 #ifdef MAC 322 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 323 if (error) 324 return (error); 325 #endif 326 foffset_lock_uio(fp, uio, flags); 327 if ((flags & FOF_OFFSET) == 0) { 328 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 329 &shmfd->shm_mtx); 330 } else { 331 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 332 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 333 } 334 335 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 336 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 337 foffset_unlock_uio(fp, uio, flags); 338 return (error); 339 } 340 341 static int 342 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 343 struct thread *td) 344 { 345 struct shmfd *shmfd; 346 #ifdef MAC 347 int error; 348 #endif 349 350 shmfd = fp->f_data; 351 #ifdef MAC 352 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 353 if (error) 354 return (error); 355 #endif 356 return (shm_dotruncate(shmfd, length)); 357 } 358 359 int 360 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 361 struct thread *td) 362 { 363 364 switch (com) { 365 case FIONBIO: 366 case FIOASYNC: 367 /* 368 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 369 * just like it would on an unlinked regular file 370 */ 371 return (0); 372 default: 373 return (ENOTTY); 374 } 375 } 376 377 static int 378 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 379 struct thread *td) 380 { 381 struct shmfd *shmfd; 382 #ifdef MAC 383 int error; 384 #endif 385 386 shmfd = fp->f_data; 387 388 #ifdef MAC 389 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 390 if (error) 391 return (error); 392 #endif 393 394 /* 395 * Attempt to return sanish values for fstat() on a memory file 396 * descriptor. 397 */ 398 bzero(sb, sizeof(*sb)); 399 sb->st_blksize = PAGE_SIZE; 400 sb->st_size = shmfd->shm_size; 401 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 402 mtx_lock(&shm_timestamp_lock); 403 sb->st_atim = shmfd->shm_atime; 404 sb->st_ctim = shmfd->shm_ctime; 405 sb->st_mtim = shmfd->shm_mtime; 406 sb->st_birthtim = shmfd->shm_birthtime; 407 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 408 sb->st_uid = shmfd->shm_uid; 409 sb->st_gid = shmfd->shm_gid; 410 mtx_unlock(&shm_timestamp_lock); 411 sb->st_dev = shm_dev_ino; 412 sb->st_ino = shmfd->shm_ino; 413 sb->st_nlink = shmfd->shm_object->ref_count; 414 415 return (0); 416 } 417 418 static int 419 shm_close(struct file *fp, struct thread *td) 420 { 421 struct shmfd *shmfd; 422 423 shmfd = fp->f_data; 424 fp->f_data = NULL; 425 shm_drop(shmfd); 426 427 return (0); 428 } 429 430 int 431 shm_dotruncate(struct shmfd *shmfd, off_t length) 432 { 433 vm_object_t object; 434 vm_page_t m; 435 vm_pindex_t idx, nobjsize; 436 vm_ooffset_t delta; 437 int base, rv; 438 439 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 440 object = shmfd->shm_object; 441 VM_OBJECT_WLOCK(object); 442 if (length == shmfd->shm_size) { 443 VM_OBJECT_WUNLOCK(object); 444 return (0); 445 } 446 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 447 448 /* Are we shrinking? If so, trim the end. */ 449 if (length < shmfd->shm_size) { 450 /* 451 * Disallow any requests to shrink the size if this 452 * object is mapped into the kernel. 453 */ 454 if (shmfd->shm_kmappings > 0) { 455 VM_OBJECT_WUNLOCK(object); 456 return (EBUSY); 457 } 458 459 /* 460 * Zero the truncated part of the last page. 461 */ 462 base = length & PAGE_MASK; 463 if (base != 0) { 464 idx = OFF_TO_IDX(length); 465 retry: 466 m = vm_page_lookup(object, idx); 467 if (m != NULL) { 468 if (vm_page_sleep_if_busy(m, "shmtrc")) 469 goto retry; 470 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 471 m = vm_page_alloc(object, idx, 472 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 473 if (m == NULL) 474 goto retry; 475 rv = vm_pager_get_pages(object, &m, 1, NULL, 476 NULL); 477 vm_page_lock(m); 478 if (rv == VM_PAGER_OK) { 479 /* 480 * Since the page was not resident, 481 * and therefore not recently 482 * accessed, immediately enqueue it 483 * for asynchronous laundering. The 484 * current operation is not regarded 485 * as an access. 486 */ 487 vm_page_launder(m); 488 vm_page_unlock(m); 489 vm_page_xunbusy(m); 490 } else { 491 vm_page_free(m); 492 vm_page_unlock(m); 493 VM_OBJECT_WUNLOCK(object); 494 return (EIO); 495 } 496 } 497 if (m != NULL) { 498 pmap_zero_page_area(m, base, PAGE_SIZE - base); 499 KASSERT(m->valid == VM_PAGE_BITS_ALL, 500 ("shm_dotruncate: page %p is invalid", m)); 501 vm_page_dirty(m); 502 vm_pager_page_unswapped(m); 503 } 504 } 505 delta = IDX_TO_OFF(object->size - nobjsize); 506 507 /* Toss in memory pages. */ 508 if (nobjsize < object->size) 509 vm_object_page_remove(object, nobjsize, object->size, 510 0); 511 512 /* Toss pages from swap. */ 513 if (object->type == OBJT_SWAP) 514 swap_pager_freespace(object, nobjsize, delta); 515 516 /* Free the swap accounted for shm */ 517 swap_release_by_cred(delta, object->cred); 518 object->charge -= delta; 519 } else { 520 /* Try to reserve additional swap space. */ 521 delta = IDX_TO_OFF(nobjsize - object->size); 522 if (!swap_reserve_by_cred(delta, object->cred)) { 523 VM_OBJECT_WUNLOCK(object); 524 return (ENOMEM); 525 } 526 object->charge += delta; 527 } 528 shmfd->shm_size = length; 529 mtx_lock(&shm_timestamp_lock); 530 vfs_timestamp(&shmfd->shm_ctime); 531 shmfd->shm_mtime = shmfd->shm_ctime; 532 mtx_unlock(&shm_timestamp_lock); 533 object->size = nobjsize; 534 VM_OBJECT_WUNLOCK(object); 535 return (0); 536 } 537 538 /* 539 * shmfd object management including creation and reference counting 540 * routines. 541 */ 542 struct shmfd * 543 shm_alloc(struct ucred *ucred, mode_t mode) 544 { 545 struct shmfd *shmfd; 546 547 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 548 shmfd->shm_size = 0; 549 shmfd->shm_uid = ucred->cr_uid; 550 shmfd->shm_gid = ucred->cr_gid; 551 shmfd->shm_mode = mode; 552 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 553 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 554 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 555 shmfd->shm_object->pg_color = 0; 556 VM_OBJECT_WLOCK(shmfd->shm_object); 557 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 558 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 559 VM_OBJECT_WUNLOCK(shmfd->shm_object); 560 vfs_timestamp(&shmfd->shm_birthtime); 561 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 562 shmfd->shm_birthtime; 563 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 564 refcount_init(&shmfd->shm_refs, 1); 565 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 566 rangelock_init(&shmfd->shm_rl); 567 #ifdef MAC 568 mac_posixshm_init(shmfd); 569 mac_posixshm_create(ucred, shmfd); 570 #endif 571 572 return (shmfd); 573 } 574 575 struct shmfd * 576 shm_hold(struct shmfd *shmfd) 577 { 578 579 refcount_acquire(&shmfd->shm_refs); 580 return (shmfd); 581 } 582 583 void 584 shm_drop(struct shmfd *shmfd) 585 { 586 587 if (refcount_release(&shmfd->shm_refs)) { 588 #ifdef MAC 589 mac_posixshm_destroy(shmfd); 590 #endif 591 rangelock_destroy(&shmfd->shm_rl); 592 mtx_destroy(&shmfd->shm_mtx); 593 vm_object_deallocate(shmfd->shm_object); 594 free(shmfd, M_SHMFD); 595 } 596 } 597 598 /* 599 * Determine if the credentials have sufficient permissions for a 600 * specified combination of FREAD and FWRITE. 601 */ 602 int 603 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 604 { 605 accmode_t accmode; 606 int error; 607 608 accmode = 0; 609 if (flags & FREAD) 610 accmode |= VREAD; 611 if (flags & FWRITE) 612 accmode |= VWRITE; 613 mtx_lock(&shm_timestamp_lock); 614 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 615 accmode, ucred, NULL); 616 mtx_unlock(&shm_timestamp_lock); 617 return (error); 618 } 619 620 /* 621 * Dictionary management. We maintain an in-kernel dictionary to map 622 * paths to shmfd objects. We use the FNV hash on the path to store 623 * the mappings in a hash table. 624 */ 625 static void 626 shm_init(void *arg) 627 { 628 629 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 630 sx_init(&shm_dict_lock, "shm dictionary"); 631 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 632 new_unrhdr64(&shm_ino_unr, 1); 633 shm_dev_ino = devfs_alloc_cdp_inode(); 634 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 635 } 636 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 637 638 static struct shmfd * 639 shm_lookup(char *path, Fnv32_t fnv) 640 { 641 struct shm_mapping *map; 642 643 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 644 if (map->sm_fnv != fnv) 645 continue; 646 if (strcmp(map->sm_path, path) == 0) 647 return (map->sm_shmfd); 648 } 649 650 return (NULL); 651 } 652 653 static void 654 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 655 { 656 struct shm_mapping *map; 657 658 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 659 map->sm_path = path; 660 map->sm_fnv = fnv; 661 map->sm_shmfd = shm_hold(shmfd); 662 shmfd->shm_path = path; 663 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 664 } 665 666 static int 667 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 668 { 669 struct shm_mapping *map; 670 int error; 671 672 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 673 if (map->sm_fnv != fnv) 674 continue; 675 if (strcmp(map->sm_path, path) == 0) { 676 #ifdef MAC 677 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 678 if (error) 679 return (error); 680 #endif 681 error = shm_access(map->sm_shmfd, ucred, 682 FREAD | FWRITE); 683 if (error) 684 return (error); 685 map->sm_shmfd->shm_path = NULL; 686 LIST_REMOVE(map, sm_link); 687 shm_drop(map->sm_shmfd); 688 free(map->sm_path, M_SHMFD); 689 free(map, M_SHMFD); 690 return (0); 691 } 692 } 693 694 return (ENOENT); 695 } 696 697 int 698 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 699 struct filecaps *fcaps) 700 { 701 struct filedesc *fdp; 702 struct shmfd *shmfd; 703 struct file *fp; 704 char *path; 705 const char *pr_path; 706 size_t pr_pathlen; 707 Fnv32_t fnv; 708 mode_t cmode; 709 int fd, error; 710 711 #ifdef CAPABILITY_MODE 712 /* 713 * shm_open(2) is only allowed for anonymous objects. 714 */ 715 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 716 return (ECAPMODE); 717 #endif 718 719 AUDIT_ARG_FFLAGS(flags); 720 AUDIT_ARG_MODE(mode); 721 722 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 723 return (EINVAL); 724 725 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 726 return (EINVAL); 727 728 fdp = td->td_proc->p_fd; 729 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 730 731 /* 732 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 733 * by POSIX. We allow it to be unset here so that an in-kernel 734 * interface may be written as a thin layer around shm, optionally not 735 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 736 * in sys_shm_open() to keep this implementation compliant. 737 */ 738 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 739 if (error) 740 return (error); 741 742 /* A SHM_ANON path pointer creates an anonymous object. */ 743 if (userpath == SHM_ANON) { 744 /* A read-only anonymous object is pointless. */ 745 if ((flags & O_ACCMODE) == O_RDONLY) { 746 fdclose(td, fp, fd); 747 fdrop(fp, td); 748 return (EINVAL); 749 } 750 shmfd = shm_alloc(td->td_ucred, cmode); 751 } else { 752 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 753 pr_path = td->td_ucred->cr_prison->pr_path; 754 755 /* Construct a full pathname for jailed callers. */ 756 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 757 : strlcpy(path, pr_path, MAXPATHLEN); 758 error = copyinstr(userpath, path + pr_pathlen, 759 MAXPATHLEN - pr_pathlen, NULL); 760 #ifdef KTRACE 761 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 762 ktrnamei(path); 763 #endif 764 /* Require paths to start with a '/' character. */ 765 if (error == 0 && path[pr_pathlen] != '/') 766 error = EINVAL; 767 if (error) { 768 fdclose(td, fp, fd); 769 fdrop(fp, td); 770 free(path, M_SHMFD); 771 return (error); 772 } 773 774 AUDIT_ARG_UPATH1_CANON(path); 775 fnv = fnv_32_str(path, FNV1_32_INIT); 776 sx_xlock(&shm_dict_lock); 777 shmfd = shm_lookup(path, fnv); 778 if (shmfd == NULL) { 779 /* Object does not yet exist, create it if requested. */ 780 if (flags & O_CREAT) { 781 #ifdef MAC 782 error = mac_posixshm_check_create(td->td_ucred, 783 path); 784 if (error == 0) { 785 #endif 786 shmfd = shm_alloc(td->td_ucred, cmode); 787 shm_insert(path, fnv, shmfd); 788 #ifdef MAC 789 } 790 #endif 791 } else { 792 free(path, M_SHMFD); 793 error = ENOENT; 794 } 795 } else { 796 /* 797 * Object already exists, obtain a new 798 * reference if requested and permitted. 799 */ 800 free(path, M_SHMFD); 801 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 802 error = EEXIST; 803 else { 804 #ifdef MAC 805 error = mac_posixshm_check_open(td->td_ucred, 806 shmfd, FFLAGS(flags & O_ACCMODE)); 807 if (error == 0) 808 #endif 809 error = shm_access(shmfd, td->td_ucred, 810 FFLAGS(flags & O_ACCMODE)); 811 } 812 813 /* 814 * Truncate the file back to zero length if 815 * O_TRUNC was specified and the object was 816 * opened with read/write. 817 */ 818 if (error == 0 && 819 (flags & (O_ACCMODE | O_TRUNC)) == 820 (O_RDWR | O_TRUNC)) { 821 #ifdef MAC 822 error = mac_posixshm_check_truncate( 823 td->td_ucred, fp->f_cred, shmfd); 824 if (error == 0) 825 #endif 826 shm_dotruncate(shmfd, 0); 827 } 828 if (error == 0) 829 shm_hold(shmfd); 830 } 831 sx_xunlock(&shm_dict_lock); 832 833 if (error) { 834 fdclose(td, fp, fd); 835 fdrop(fp, td); 836 return (error); 837 } 838 } 839 840 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 841 842 td->td_retval[0] = fd; 843 fdrop(fp, td); 844 845 return (0); 846 } 847 848 /* System calls. */ 849 int 850 sys_shm_open(struct thread *td, struct shm_open_args *uap) 851 { 852 853 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode, 854 NULL)); 855 } 856 857 int 858 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 859 { 860 char *path; 861 const char *pr_path; 862 size_t pr_pathlen; 863 Fnv32_t fnv; 864 int error; 865 866 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 867 pr_path = td->td_ucred->cr_prison->pr_path; 868 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 869 : strlcpy(path, pr_path, MAXPATHLEN); 870 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 871 NULL); 872 if (error) { 873 free(path, M_TEMP); 874 return (error); 875 } 876 #ifdef KTRACE 877 if (KTRPOINT(curthread, KTR_NAMEI)) 878 ktrnamei(path); 879 #endif 880 AUDIT_ARG_UPATH1_CANON(path); 881 fnv = fnv_32_str(path, FNV1_32_INIT); 882 sx_xlock(&shm_dict_lock); 883 error = shm_remove(path, fnv, td->td_ucred); 884 sx_xunlock(&shm_dict_lock); 885 free(path, M_TEMP); 886 887 return (error); 888 } 889 890 int 891 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 892 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 893 vm_ooffset_t foff, struct thread *td) 894 { 895 struct shmfd *shmfd; 896 vm_prot_t maxprot; 897 int error; 898 bool writecnt; 899 900 shmfd = fp->f_data; 901 maxprot = VM_PROT_NONE; 902 903 /* FREAD should always be set. */ 904 if ((fp->f_flag & FREAD) != 0) 905 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 906 if ((fp->f_flag & FWRITE) != 0) 907 maxprot |= VM_PROT_WRITE; 908 909 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; 910 911 /* Don't permit shared writable mappings on read-only descriptors. */ 912 if (writecnt && (maxprot & VM_PROT_WRITE) == 0) 913 return (EACCES); 914 maxprot &= cap_maxprot; 915 916 /* See comment in vn_mmap(). */ 917 if ( 918 #ifdef _LP64 919 objsize > OFF_MAX || 920 #endif 921 foff < 0 || foff > OFF_MAX - objsize) 922 return (EINVAL); 923 924 #ifdef MAC 925 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 926 if (error != 0) 927 return (error); 928 #endif 929 930 mtx_lock(&shm_timestamp_lock); 931 vfs_timestamp(&shmfd->shm_atime); 932 mtx_unlock(&shm_timestamp_lock); 933 vm_object_reference(shmfd->shm_object); 934 935 if (writecnt) 936 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 937 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 938 shmfd->shm_object, foff, writecnt, td); 939 if (error != 0) { 940 if (writecnt) 941 vm_pager_release_writecount(shmfd->shm_object, 0, 942 objsize); 943 vm_object_deallocate(shmfd->shm_object); 944 } 945 return (error); 946 } 947 948 static int 949 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 950 struct thread *td) 951 { 952 struct shmfd *shmfd; 953 int error; 954 955 error = 0; 956 shmfd = fp->f_data; 957 mtx_lock(&shm_timestamp_lock); 958 /* 959 * SUSv4 says that x bits of permission need not be affected. 960 * Be consistent with our shm_open there. 961 */ 962 #ifdef MAC 963 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 964 if (error != 0) 965 goto out; 966 #endif 967 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 968 shmfd->shm_gid, VADMIN, active_cred, NULL); 969 if (error != 0) 970 goto out; 971 shmfd->shm_mode = mode & ACCESSPERMS; 972 out: 973 mtx_unlock(&shm_timestamp_lock); 974 return (error); 975 } 976 977 static int 978 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 979 struct thread *td) 980 { 981 struct shmfd *shmfd; 982 int error; 983 984 error = 0; 985 shmfd = fp->f_data; 986 mtx_lock(&shm_timestamp_lock); 987 #ifdef MAC 988 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 989 if (error != 0) 990 goto out; 991 #endif 992 if (uid == (uid_t)-1) 993 uid = shmfd->shm_uid; 994 if (gid == (gid_t)-1) 995 gid = shmfd->shm_gid; 996 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 997 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 998 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 999 goto out; 1000 shmfd->shm_uid = uid; 1001 shmfd->shm_gid = gid; 1002 out: 1003 mtx_unlock(&shm_timestamp_lock); 1004 return (error); 1005 } 1006 1007 /* 1008 * Helper routines to allow the backing object of a shared memory file 1009 * descriptor to be mapped in the kernel. 1010 */ 1011 int 1012 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1013 { 1014 struct shmfd *shmfd; 1015 vm_offset_t kva, ofs; 1016 vm_object_t obj; 1017 int rv; 1018 1019 if (fp->f_type != DTYPE_SHM) 1020 return (EINVAL); 1021 shmfd = fp->f_data; 1022 obj = shmfd->shm_object; 1023 VM_OBJECT_WLOCK(obj); 1024 /* 1025 * XXXRW: This validation is probably insufficient, and subject to 1026 * sign errors. It should be fixed. 1027 */ 1028 if (offset >= shmfd->shm_size || 1029 offset + size > round_page(shmfd->shm_size)) { 1030 VM_OBJECT_WUNLOCK(obj); 1031 return (EINVAL); 1032 } 1033 1034 shmfd->shm_kmappings++; 1035 vm_object_reference_locked(obj); 1036 VM_OBJECT_WUNLOCK(obj); 1037 1038 /* Map the object into the kernel_map and wire it. */ 1039 kva = vm_map_min(kernel_map); 1040 ofs = offset & PAGE_MASK; 1041 offset = trunc_page(offset); 1042 size = round_page(size + ofs); 1043 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1044 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1045 VM_PROT_READ | VM_PROT_WRITE, 0); 1046 if (rv == KERN_SUCCESS) { 1047 rv = vm_map_wire(kernel_map, kva, kva + size, 1048 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1049 if (rv == KERN_SUCCESS) { 1050 *memp = (void *)(kva + ofs); 1051 return (0); 1052 } 1053 vm_map_remove(kernel_map, kva, kva + size); 1054 } else 1055 vm_object_deallocate(obj); 1056 1057 /* On failure, drop our mapping reference. */ 1058 VM_OBJECT_WLOCK(obj); 1059 shmfd->shm_kmappings--; 1060 VM_OBJECT_WUNLOCK(obj); 1061 1062 return (vm_mmap_to_errno(rv)); 1063 } 1064 1065 /* 1066 * We require the caller to unmap the entire entry. This allows us to 1067 * safely decrement shm_kmappings when a mapping is removed. 1068 */ 1069 int 1070 shm_unmap(struct file *fp, void *mem, size_t size) 1071 { 1072 struct shmfd *shmfd; 1073 vm_map_entry_t entry; 1074 vm_offset_t kva, ofs; 1075 vm_object_t obj; 1076 vm_pindex_t pindex; 1077 vm_prot_t prot; 1078 boolean_t wired; 1079 vm_map_t map; 1080 int rv; 1081 1082 if (fp->f_type != DTYPE_SHM) 1083 return (EINVAL); 1084 shmfd = fp->f_data; 1085 kva = (vm_offset_t)mem; 1086 ofs = kva & PAGE_MASK; 1087 kva = trunc_page(kva); 1088 size = round_page(size + ofs); 1089 map = kernel_map; 1090 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1091 &obj, &pindex, &prot, &wired); 1092 if (rv != KERN_SUCCESS) 1093 return (EINVAL); 1094 if (entry->start != kva || entry->end != kva + size) { 1095 vm_map_lookup_done(map, entry); 1096 return (EINVAL); 1097 } 1098 vm_map_lookup_done(map, entry); 1099 if (obj != shmfd->shm_object) 1100 return (EINVAL); 1101 vm_map_remove(map, kva, kva + size); 1102 VM_OBJECT_WLOCK(obj); 1103 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1104 shmfd->shm_kmappings--; 1105 VM_OBJECT_WUNLOCK(obj); 1106 return (0); 1107 } 1108 1109 static int 1110 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1111 { 1112 const char *path, *pr_path; 1113 size_t pr_pathlen; 1114 bool visible; 1115 1116 sx_assert(&shm_dict_lock, SA_LOCKED); 1117 kif->kf_type = KF_TYPE_SHM; 1118 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1119 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1120 if (shmfd->shm_path != NULL) { 1121 if (shmfd->shm_path != NULL) { 1122 path = shmfd->shm_path; 1123 pr_path = curthread->td_ucred->cr_prison->pr_path; 1124 if (strcmp(pr_path, "/") != 0) { 1125 /* Return the jail-rooted pathname. */ 1126 pr_pathlen = strlen(pr_path); 1127 visible = strncmp(path, pr_path, pr_pathlen) 1128 == 0 && path[pr_pathlen] == '/'; 1129 if (list && !visible) 1130 return (EPERM); 1131 if (visible) 1132 path += pr_pathlen; 1133 } 1134 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1135 } 1136 } 1137 return (0); 1138 } 1139 1140 static int 1141 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1142 struct filedesc *fdp __unused) 1143 { 1144 int res; 1145 1146 sx_slock(&shm_dict_lock); 1147 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1148 sx_sunlock(&shm_dict_lock); 1149 return (res); 1150 } 1151 1152 static int 1153 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1154 { 1155 struct shm_mapping *shmm; 1156 struct sbuf sb; 1157 struct kinfo_file kif; 1158 u_long i; 1159 ssize_t curlen; 1160 int error, error2; 1161 1162 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1163 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1164 curlen = 0; 1165 error = 0; 1166 sx_slock(&shm_dict_lock); 1167 for (i = 0; i < shm_hash + 1; i++) { 1168 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1169 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1170 &kif, true); 1171 if (error == EPERM) 1172 continue; 1173 if (error != 0) 1174 break; 1175 pack_kinfo(&kif); 1176 if (req->oldptr != NULL && 1177 kif.kf_structsize + curlen > req->oldlen) 1178 break; 1179 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1180 0 : ENOMEM; 1181 if (error != 0) 1182 break; 1183 curlen += kif.kf_structsize; 1184 } 1185 } 1186 sx_sunlock(&shm_dict_lock); 1187 error2 = sbuf_finish(&sb); 1188 sbuf_delete(&sb); 1189 return (error != 0 ? error : error2); 1190 } 1191 1192 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1193 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1194 NULL, 0, sysctl_posix_shm_list, "", 1195 "POSIX SHM list"); 1196