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 rv = vm_page_grab_valid(&m, obj, idx, 192 VM_ALLOC_NORMAL | VM_ALLOC_WIRED | VM_ALLOC_NOBUSY); 193 if (rv != VM_PAGER_OK) { 194 VM_OBJECT_WUNLOCK(obj); 195 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 196 obj, idx, rv); 197 return (EIO); 198 } 199 VM_OBJECT_WUNLOCK(obj); 200 error = uiomove_fromphys(&m, offset, tlen, uio); 201 if (uio->uio_rw == UIO_WRITE && error == 0) { 202 VM_OBJECT_WLOCK(obj); 203 vm_page_dirty(m); 204 vm_pager_page_unswapped(m); 205 VM_OBJECT_WUNLOCK(obj); 206 } 207 vm_page_unwire(m, PQ_ACTIVE); 208 209 return (error); 210 } 211 212 int 213 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 214 { 215 ssize_t resid; 216 size_t len; 217 int error; 218 219 error = 0; 220 while ((resid = uio->uio_resid) > 0) { 221 if (obj_size <= uio->uio_offset) 222 break; 223 len = MIN(obj_size - uio->uio_offset, resid); 224 if (len == 0) 225 break; 226 error = uiomove_object_page(obj, len, uio); 227 if (error != 0 || resid == uio->uio_resid) 228 break; 229 } 230 return (error); 231 } 232 233 static int 234 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 235 { 236 struct shmfd *shmfd; 237 off_t foffset; 238 int error; 239 240 shmfd = fp->f_data; 241 foffset = foffset_lock(fp, 0); 242 error = 0; 243 switch (whence) { 244 case L_INCR: 245 if (foffset < 0 || 246 (offset > 0 && foffset > OFF_MAX - offset)) { 247 error = EOVERFLOW; 248 break; 249 } 250 offset += foffset; 251 break; 252 case L_XTND: 253 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 254 error = EOVERFLOW; 255 break; 256 } 257 offset += shmfd->shm_size; 258 break; 259 case L_SET: 260 break; 261 default: 262 error = EINVAL; 263 } 264 if (error == 0) { 265 if (offset < 0 || offset > shmfd->shm_size) 266 error = EINVAL; 267 else 268 td->td_uretoff.tdu_off = offset; 269 } 270 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 271 return (error); 272 } 273 274 static int 275 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 276 int flags, struct thread *td) 277 { 278 struct shmfd *shmfd; 279 void *rl_cookie; 280 int error; 281 282 shmfd = fp->f_data; 283 #ifdef MAC 284 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 285 if (error) 286 return (error); 287 #endif 288 foffset_lock_uio(fp, uio, flags); 289 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 290 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 291 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 292 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 293 foffset_unlock_uio(fp, uio, flags); 294 return (error); 295 } 296 297 static int 298 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 299 int flags, struct thread *td) 300 { 301 struct shmfd *shmfd; 302 void *rl_cookie; 303 int error; 304 305 shmfd = fp->f_data; 306 #ifdef MAC 307 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 308 if (error) 309 return (error); 310 #endif 311 foffset_lock_uio(fp, uio, flags); 312 if ((flags & FOF_OFFSET) == 0) { 313 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 314 &shmfd->shm_mtx); 315 } else { 316 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 317 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 318 } 319 320 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 321 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 322 foffset_unlock_uio(fp, uio, flags); 323 return (error); 324 } 325 326 static int 327 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 328 struct thread *td) 329 { 330 struct shmfd *shmfd; 331 #ifdef MAC 332 int error; 333 #endif 334 335 shmfd = fp->f_data; 336 #ifdef MAC 337 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 338 if (error) 339 return (error); 340 #endif 341 return (shm_dotruncate(shmfd, length)); 342 } 343 344 int 345 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 346 struct thread *td) 347 { 348 349 switch (com) { 350 case FIONBIO: 351 case FIOASYNC: 352 /* 353 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 354 * just like it would on an unlinked regular file 355 */ 356 return (0); 357 default: 358 return (ENOTTY); 359 } 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 = howmany(sb->st_size, 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 sb->st_nlink = shmfd->shm_object->ref_count; 399 400 return (0); 401 } 402 403 static int 404 shm_close(struct file *fp, struct thread *td) 405 { 406 struct shmfd *shmfd; 407 408 shmfd = fp->f_data; 409 fp->f_data = NULL; 410 shm_drop(shmfd); 411 412 return (0); 413 } 414 415 int 416 shm_dotruncate(struct shmfd *shmfd, off_t length) 417 { 418 vm_object_t object; 419 vm_page_t m; 420 vm_pindex_t idx, nobjsize; 421 vm_ooffset_t delta; 422 int base, rv; 423 424 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 425 object = shmfd->shm_object; 426 VM_OBJECT_WLOCK(object); 427 if (length == shmfd->shm_size) { 428 VM_OBJECT_WUNLOCK(object); 429 return (0); 430 } 431 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 432 433 /* Are we shrinking? If so, trim the end. */ 434 if (length < shmfd->shm_size) { 435 /* 436 * Disallow any requests to shrink the size if this 437 * object is mapped into the kernel. 438 */ 439 if (shmfd->shm_kmappings > 0) { 440 VM_OBJECT_WUNLOCK(object); 441 return (EBUSY); 442 } 443 444 /* 445 * Zero the truncated part of the last page. 446 */ 447 base = length & PAGE_MASK; 448 if (base != 0) { 449 idx = OFF_TO_IDX(length); 450 retry: 451 m = vm_page_lookup(object, idx); 452 if (m != NULL) { 453 if (vm_page_sleep_if_busy(m, "shmtrc")) 454 goto retry; 455 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 456 m = vm_page_alloc(object, idx, 457 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 458 if (m == NULL) 459 goto retry; 460 rv = vm_pager_get_pages(object, &m, 1, NULL, 461 NULL); 462 if (rv == VM_PAGER_OK) { 463 /* 464 * Since the page was not resident, 465 * and therefore not recently 466 * accessed, immediately enqueue it 467 * for asynchronous laundering. The 468 * current operation is not regarded 469 * as an access. 470 */ 471 vm_page_launder(m); 472 vm_page_xunbusy(m); 473 } else { 474 vm_page_free(m); 475 VM_OBJECT_WUNLOCK(object); 476 return (EIO); 477 } 478 } 479 if (m != NULL) { 480 pmap_zero_page_area(m, base, PAGE_SIZE - base); 481 KASSERT(m->valid == VM_PAGE_BITS_ALL, 482 ("shm_dotruncate: page %p is invalid", m)); 483 vm_page_dirty(m); 484 vm_pager_page_unswapped(m); 485 } 486 } 487 delta = IDX_TO_OFF(object->size - nobjsize); 488 489 /* Toss in memory pages. */ 490 if (nobjsize < object->size) 491 vm_object_page_remove(object, nobjsize, object->size, 492 0); 493 494 /* Toss pages from swap. */ 495 if (object->type == OBJT_SWAP) 496 swap_pager_freespace(object, nobjsize, delta); 497 498 /* Free the swap accounted for shm */ 499 swap_release_by_cred(delta, object->cred); 500 object->charge -= delta; 501 } else { 502 /* Try to reserve additional swap space. */ 503 delta = IDX_TO_OFF(nobjsize - object->size); 504 if (!swap_reserve_by_cred(delta, object->cred)) { 505 VM_OBJECT_WUNLOCK(object); 506 return (ENOMEM); 507 } 508 object->charge += delta; 509 } 510 shmfd->shm_size = length; 511 mtx_lock(&shm_timestamp_lock); 512 vfs_timestamp(&shmfd->shm_ctime); 513 shmfd->shm_mtime = shmfd->shm_ctime; 514 mtx_unlock(&shm_timestamp_lock); 515 object->size = nobjsize; 516 VM_OBJECT_WUNLOCK(object); 517 return (0); 518 } 519 520 /* 521 * shmfd object management including creation and reference counting 522 * routines. 523 */ 524 struct shmfd * 525 shm_alloc(struct ucred *ucred, mode_t mode) 526 { 527 struct shmfd *shmfd; 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_SWAP, 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 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 546 refcount_init(&shmfd->shm_refs, 1); 547 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 548 rangelock_init(&shmfd->shm_rl); 549 #ifdef MAC 550 mac_posixshm_init(shmfd); 551 mac_posixshm_create(ucred, shmfd); 552 #endif 553 554 return (shmfd); 555 } 556 557 struct shmfd * 558 shm_hold(struct shmfd *shmfd) 559 { 560 561 refcount_acquire(&shmfd->shm_refs); 562 return (shmfd); 563 } 564 565 void 566 shm_drop(struct shmfd *shmfd) 567 { 568 569 if (refcount_release(&shmfd->shm_refs)) { 570 #ifdef MAC 571 mac_posixshm_destroy(shmfd); 572 #endif 573 rangelock_destroy(&shmfd->shm_rl); 574 mtx_destroy(&shmfd->shm_mtx); 575 vm_object_deallocate(shmfd->shm_object); 576 free(shmfd, M_SHMFD); 577 } 578 } 579 580 /* 581 * Determine if the credentials have sufficient permissions for a 582 * specified combination of FREAD and FWRITE. 583 */ 584 int 585 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 586 { 587 accmode_t accmode; 588 int error; 589 590 accmode = 0; 591 if (flags & FREAD) 592 accmode |= VREAD; 593 if (flags & FWRITE) 594 accmode |= VWRITE; 595 mtx_lock(&shm_timestamp_lock); 596 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 597 accmode, ucred, NULL); 598 mtx_unlock(&shm_timestamp_lock); 599 return (error); 600 } 601 602 /* 603 * Dictionary management. We maintain an in-kernel dictionary to map 604 * paths to shmfd objects. We use the FNV hash on the path to store 605 * the mappings in a hash table. 606 */ 607 static void 608 shm_init(void *arg) 609 { 610 611 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 612 sx_init(&shm_dict_lock, "shm dictionary"); 613 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 614 new_unrhdr64(&shm_ino_unr, 1); 615 shm_dev_ino = devfs_alloc_cdp_inode(); 616 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 617 } 618 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 619 620 static struct shmfd * 621 shm_lookup(char *path, Fnv32_t fnv) 622 { 623 struct shm_mapping *map; 624 625 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 626 if (map->sm_fnv != fnv) 627 continue; 628 if (strcmp(map->sm_path, path) == 0) 629 return (map->sm_shmfd); 630 } 631 632 return (NULL); 633 } 634 635 static void 636 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 637 { 638 struct shm_mapping *map; 639 640 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 641 map->sm_path = path; 642 map->sm_fnv = fnv; 643 map->sm_shmfd = shm_hold(shmfd); 644 shmfd->shm_path = path; 645 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 646 } 647 648 static int 649 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 650 { 651 struct shm_mapping *map; 652 int error; 653 654 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 655 if (map->sm_fnv != fnv) 656 continue; 657 if (strcmp(map->sm_path, path) == 0) { 658 #ifdef MAC 659 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 660 if (error) 661 return (error); 662 #endif 663 error = shm_access(map->sm_shmfd, ucred, 664 FREAD | FWRITE); 665 if (error) 666 return (error); 667 map->sm_shmfd->shm_path = NULL; 668 LIST_REMOVE(map, sm_link); 669 shm_drop(map->sm_shmfd); 670 free(map->sm_path, M_SHMFD); 671 free(map, M_SHMFD); 672 return (0); 673 } 674 } 675 676 return (ENOENT); 677 } 678 679 int 680 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 681 struct filecaps *fcaps) 682 { 683 struct filedesc *fdp; 684 struct shmfd *shmfd; 685 struct file *fp; 686 char *path; 687 const char *pr_path; 688 size_t pr_pathlen; 689 Fnv32_t fnv; 690 mode_t cmode; 691 int fd, error; 692 693 #ifdef CAPABILITY_MODE 694 /* 695 * shm_open(2) is only allowed for anonymous objects. 696 */ 697 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 698 return (ECAPMODE); 699 #endif 700 701 AUDIT_ARG_FFLAGS(flags); 702 AUDIT_ARG_MODE(mode); 703 704 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 705 return (EINVAL); 706 707 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 708 return (EINVAL); 709 710 fdp = td->td_proc->p_fd; 711 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 712 713 /* 714 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 715 * by POSIX. We allow it to be unset here so that an in-kernel 716 * interface may be written as a thin layer around shm, optionally not 717 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 718 * in sys_shm_open() to keep this implementation compliant. 719 */ 720 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 721 if (error) 722 return (error); 723 724 /* A SHM_ANON path pointer creates an anonymous object. */ 725 if (userpath == SHM_ANON) { 726 /* A read-only anonymous object is pointless. */ 727 if ((flags & O_ACCMODE) == O_RDONLY) { 728 fdclose(td, fp, fd); 729 fdrop(fp, td); 730 return (EINVAL); 731 } 732 shmfd = shm_alloc(td->td_ucred, cmode); 733 } else { 734 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 735 pr_path = td->td_ucred->cr_prison->pr_path; 736 737 /* Construct a full pathname for jailed callers. */ 738 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 739 : strlcpy(path, pr_path, MAXPATHLEN); 740 error = copyinstr(userpath, path + pr_pathlen, 741 MAXPATHLEN - pr_pathlen, NULL); 742 #ifdef KTRACE 743 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 744 ktrnamei(path); 745 #endif 746 /* Require paths to start with a '/' character. */ 747 if (error == 0 && path[pr_pathlen] != '/') 748 error = EINVAL; 749 if (error) { 750 fdclose(td, fp, fd); 751 fdrop(fp, td); 752 free(path, M_SHMFD); 753 return (error); 754 } 755 756 AUDIT_ARG_UPATH1_CANON(path); 757 fnv = fnv_32_str(path, FNV1_32_INIT); 758 sx_xlock(&shm_dict_lock); 759 shmfd = shm_lookup(path, fnv); 760 if (shmfd == NULL) { 761 /* Object does not yet exist, create it if requested. */ 762 if (flags & O_CREAT) { 763 #ifdef MAC 764 error = mac_posixshm_check_create(td->td_ucred, 765 path); 766 if (error == 0) { 767 #endif 768 shmfd = shm_alloc(td->td_ucred, cmode); 769 shm_insert(path, fnv, shmfd); 770 #ifdef MAC 771 } 772 #endif 773 } else { 774 free(path, M_SHMFD); 775 error = ENOENT; 776 } 777 } else { 778 /* 779 * Object already exists, obtain a new 780 * reference if requested and permitted. 781 */ 782 free(path, M_SHMFD); 783 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 784 error = EEXIST; 785 else { 786 #ifdef MAC 787 error = mac_posixshm_check_open(td->td_ucred, 788 shmfd, FFLAGS(flags & O_ACCMODE)); 789 if (error == 0) 790 #endif 791 error = shm_access(shmfd, td->td_ucred, 792 FFLAGS(flags & O_ACCMODE)); 793 } 794 795 /* 796 * Truncate the file back to zero length if 797 * O_TRUNC was specified and the object was 798 * opened with read/write. 799 */ 800 if (error == 0 && 801 (flags & (O_ACCMODE | O_TRUNC)) == 802 (O_RDWR | O_TRUNC)) { 803 #ifdef MAC 804 error = mac_posixshm_check_truncate( 805 td->td_ucred, fp->f_cred, shmfd); 806 if (error == 0) 807 #endif 808 shm_dotruncate(shmfd, 0); 809 } 810 if (error == 0) 811 shm_hold(shmfd); 812 } 813 sx_xunlock(&shm_dict_lock); 814 815 if (error) { 816 fdclose(td, fp, fd); 817 fdrop(fp, td); 818 return (error); 819 } 820 } 821 822 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 823 824 td->td_retval[0] = fd; 825 fdrop(fp, td); 826 827 return (0); 828 } 829 830 /* System calls. */ 831 int 832 sys_shm_open(struct thread *td, struct shm_open_args *uap) 833 { 834 835 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode, 836 NULL)); 837 } 838 839 int 840 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 841 { 842 char *path; 843 const char *pr_path; 844 size_t pr_pathlen; 845 Fnv32_t fnv; 846 int error; 847 848 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 849 pr_path = td->td_ucred->cr_prison->pr_path; 850 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 851 : strlcpy(path, pr_path, MAXPATHLEN); 852 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 853 NULL); 854 if (error) { 855 free(path, M_TEMP); 856 return (error); 857 } 858 #ifdef KTRACE 859 if (KTRPOINT(curthread, KTR_NAMEI)) 860 ktrnamei(path); 861 #endif 862 AUDIT_ARG_UPATH1_CANON(path); 863 fnv = fnv_32_str(path, FNV1_32_INIT); 864 sx_xlock(&shm_dict_lock); 865 error = shm_remove(path, fnv, td->td_ucred); 866 sx_xunlock(&shm_dict_lock); 867 free(path, M_TEMP); 868 869 return (error); 870 } 871 872 int 873 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 874 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 875 vm_ooffset_t foff, struct thread *td) 876 { 877 struct shmfd *shmfd; 878 vm_prot_t maxprot; 879 int error; 880 bool writecnt; 881 882 shmfd = fp->f_data; 883 maxprot = VM_PROT_NONE; 884 885 /* FREAD should always be set. */ 886 if ((fp->f_flag & FREAD) != 0) 887 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 888 if ((fp->f_flag & FWRITE) != 0) 889 maxprot |= VM_PROT_WRITE; 890 891 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; 892 893 /* Don't permit shared writable mappings on read-only descriptors. */ 894 if (writecnt && (maxprot & VM_PROT_WRITE) == 0) 895 return (EACCES); 896 maxprot &= cap_maxprot; 897 898 /* See comment in vn_mmap(). */ 899 if ( 900 #ifdef _LP64 901 objsize > OFF_MAX || 902 #endif 903 foff < 0 || foff > OFF_MAX - objsize) 904 return (EINVAL); 905 906 #ifdef MAC 907 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 908 if (error != 0) 909 return (error); 910 #endif 911 912 mtx_lock(&shm_timestamp_lock); 913 vfs_timestamp(&shmfd->shm_atime); 914 mtx_unlock(&shm_timestamp_lock); 915 vm_object_reference(shmfd->shm_object); 916 917 if (writecnt) 918 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 919 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 920 shmfd->shm_object, foff, writecnt, td); 921 if (error != 0) { 922 if (writecnt) 923 vm_pager_release_writecount(shmfd->shm_object, 0, 924 objsize); 925 vm_object_deallocate(shmfd->shm_object); 926 } 927 return (error); 928 } 929 930 static int 931 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 932 struct thread *td) 933 { 934 struct shmfd *shmfd; 935 int error; 936 937 error = 0; 938 shmfd = fp->f_data; 939 mtx_lock(&shm_timestamp_lock); 940 /* 941 * SUSv4 says that x bits of permission need not be affected. 942 * Be consistent with our shm_open there. 943 */ 944 #ifdef MAC 945 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 946 if (error != 0) 947 goto out; 948 #endif 949 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 950 shmfd->shm_gid, VADMIN, active_cred, NULL); 951 if (error != 0) 952 goto out; 953 shmfd->shm_mode = mode & ACCESSPERMS; 954 out: 955 mtx_unlock(&shm_timestamp_lock); 956 return (error); 957 } 958 959 static int 960 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 961 struct thread *td) 962 { 963 struct shmfd *shmfd; 964 int error; 965 966 error = 0; 967 shmfd = fp->f_data; 968 mtx_lock(&shm_timestamp_lock); 969 #ifdef MAC 970 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 971 if (error != 0) 972 goto out; 973 #endif 974 if (uid == (uid_t)-1) 975 uid = shmfd->shm_uid; 976 if (gid == (gid_t)-1) 977 gid = shmfd->shm_gid; 978 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 979 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 980 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 981 goto out; 982 shmfd->shm_uid = uid; 983 shmfd->shm_gid = gid; 984 out: 985 mtx_unlock(&shm_timestamp_lock); 986 return (error); 987 } 988 989 /* 990 * Helper routines to allow the backing object of a shared memory file 991 * descriptor to be mapped in the kernel. 992 */ 993 int 994 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 995 { 996 struct shmfd *shmfd; 997 vm_offset_t kva, ofs; 998 vm_object_t obj; 999 int rv; 1000 1001 if (fp->f_type != DTYPE_SHM) 1002 return (EINVAL); 1003 shmfd = fp->f_data; 1004 obj = shmfd->shm_object; 1005 VM_OBJECT_WLOCK(obj); 1006 /* 1007 * XXXRW: This validation is probably insufficient, and subject to 1008 * sign errors. It should be fixed. 1009 */ 1010 if (offset >= shmfd->shm_size || 1011 offset + size > round_page(shmfd->shm_size)) { 1012 VM_OBJECT_WUNLOCK(obj); 1013 return (EINVAL); 1014 } 1015 1016 shmfd->shm_kmappings++; 1017 vm_object_reference_locked(obj); 1018 VM_OBJECT_WUNLOCK(obj); 1019 1020 /* Map the object into the kernel_map and wire it. */ 1021 kva = vm_map_min(kernel_map); 1022 ofs = offset & PAGE_MASK; 1023 offset = trunc_page(offset); 1024 size = round_page(size + ofs); 1025 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1026 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1027 VM_PROT_READ | VM_PROT_WRITE, 0); 1028 if (rv == KERN_SUCCESS) { 1029 rv = vm_map_wire(kernel_map, kva, kva + size, 1030 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1031 if (rv == KERN_SUCCESS) { 1032 *memp = (void *)(kva + ofs); 1033 return (0); 1034 } 1035 vm_map_remove(kernel_map, kva, kva + size); 1036 } else 1037 vm_object_deallocate(obj); 1038 1039 /* On failure, drop our mapping reference. */ 1040 VM_OBJECT_WLOCK(obj); 1041 shmfd->shm_kmappings--; 1042 VM_OBJECT_WUNLOCK(obj); 1043 1044 return (vm_mmap_to_errno(rv)); 1045 } 1046 1047 /* 1048 * We require the caller to unmap the entire entry. This allows us to 1049 * safely decrement shm_kmappings when a mapping is removed. 1050 */ 1051 int 1052 shm_unmap(struct file *fp, void *mem, size_t size) 1053 { 1054 struct shmfd *shmfd; 1055 vm_map_entry_t entry; 1056 vm_offset_t kva, ofs; 1057 vm_object_t obj; 1058 vm_pindex_t pindex; 1059 vm_prot_t prot; 1060 boolean_t wired; 1061 vm_map_t map; 1062 int rv; 1063 1064 if (fp->f_type != DTYPE_SHM) 1065 return (EINVAL); 1066 shmfd = fp->f_data; 1067 kva = (vm_offset_t)mem; 1068 ofs = kva & PAGE_MASK; 1069 kva = trunc_page(kva); 1070 size = round_page(size + ofs); 1071 map = kernel_map; 1072 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1073 &obj, &pindex, &prot, &wired); 1074 if (rv != KERN_SUCCESS) 1075 return (EINVAL); 1076 if (entry->start != kva || entry->end != kva + size) { 1077 vm_map_lookup_done(map, entry); 1078 return (EINVAL); 1079 } 1080 vm_map_lookup_done(map, entry); 1081 if (obj != shmfd->shm_object) 1082 return (EINVAL); 1083 vm_map_remove(map, kva, kva + size); 1084 VM_OBJECT_WLOCK(obj); 1085 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1086 shmfd->shm_kmappings--; 1087 VM_OBJECT_WUNLOCK(obj); 1088 return (0); 1089 } 1090 1091 static int 1092 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1093 { 1094 const char *path, *pr_path; 1095 size_t pr_pathlen; 1096 bool visible; 1097 1098 sx_assert(&shm_dict_lock, SA_LOCKED); 1099 kif->kf_type = KF_TYPE_SHM; 1100 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1101 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1102 if (shmfd->shm_path != NULL) { 1103 if (shmfd->shm_path != NULL) { 1104 path = shmfd->shm_path; 1105 pr_path = curthread->td_ucred->cr_prison->pr_path; 1106 if (strcmp(pr_path, "/") != 0) { 1107 /* Return the jail-rooted pathname. */ 1108 pr_pathlen = strlen(pr_path); 1109 visible = strncmp(path, pr_path, pr_pathlen) 1110 == 0 && path[pr_pathlen] == '/'; 1111 if (list && !visible) 1112 return (EPERM); 1113 if (visible) 1114 path += pr_pathlen; 1115 } 1116 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1117 } 1118 } 1119 return (0); 1120 } 1121 1122 static int 1123 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1124 struct filedesc *fdp __unused) 1125 { 1126 int res; 1127 1128 sx_slock(&shm_dict_lock); 1129 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1130 sx_sunlock(&shm_dict_lock); 1131 return (res); 1132 } 1133 1134 static int 1135 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1136 { 1137 struct shm_mapping *shmm; 1138 struct sbuf sb; 1139 struct kinfo_file kif; 1140 u_long i; 1141 ssize_t curlen; 1142 int error, error2; 1143 1144 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1145 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1146 curlen = 0; 1147 error = 0; 1148 sx_slock(&shm_dict_lock); 1149 for (i = 0; i < shm_hash + 1; i++) { 1150 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1151 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1152 &kif, true); 1153 if (error == EPERM) 1154 continue; 1155 if (error != 0) 1156 break; 1157 pack_kinfo(&kif); 1158 if (req->oldptr != NULL && 1159 kif.kf_structsize + curlen > req->oldlen) 1160 break; 1161 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1162 0 : ENOMEM; 1163 if (error != 0) 1164 break; 1165 curlen += kif.kf_structsize; 1166 } 1167 } 1168 sx_sunlock(&shm_dict_lock); 1169 error2 = sbuf_finish(&sb); 1170 sbuf_delete(&sb); 1171 return (error != 0 ? error : error2); 1172 } 1173 1174 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1175 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1176 NULL, 0, sysctl_posix_shm_list, "", 1177 "POSIX SHM list"); 1178