1 /*- 2 * Copyright (c) 2006, 2011 Robert N. M. Watson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 /* 28 * Support for shared swap-backed anonymous memory objects via 29 * shm_open(2) and shm_unlink(2). While most of the implementation is 30 * here, vm_mmap.c contains mapping logic changes. 31 * 32 * TODO: 33 * 34 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) 35 * and ipcrm(1) be expanded or should new tools to manage both POSIX 36 * kernel semaphores and POSIX shared memory be written? 37 * 38 * (2) Add support for this file type to fstat(1). 39 * 40 * (3) Resource limits? Does this need its own resource limits or are the 41 * existing limits in mmap(2) sufficient? 42 * 43 * (4) Partial page truncation. vnode_pager_setsize() will zero any parts 44 * of a partially mapped page as a result of ftruncate(2)/truncate(2). 45 * We can do the same (with the same pmap evil), but do we need to 46 * worry about the bits on disk if the page is swapped out or will the 47 * swapper zero the parts of a page that are invalid if the page is 48 * swapped back in for us? 49 */ 50 51 #include <sys/cdefs.h> 52 __FBSDID("$FreeBSD$"); 53 54 #include "opt_capsicum.h" 55 56 #include <sys/param.h> 57 #include <sys/capability.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/lock.h> 64 #include <sys/malloc.h> 65 #include <sys/mman.h> 66 #include <sys/mutex.h> 67 #include <sys/priv.h> 68 #include <sys/proc.h> 69 #include <sys/refcount.h> 70 #include <sys/resourcevar.h> 71 #include <sys/stat.h> 72 #include <sys/sysctl.h> 73 #include <sys/sysproto.h> 74 #include <sys/systm.h> 75 #include <sys/sx.h> 76 #include <sys/time.h> 77 #include <sys/vnode.h> 78 79 #include <security/mac/mac_framework.h> 80 81 #include <vm/vm.h> 82 #include <vm/vm_param.h> 83 #include <vm/pmap.h> 84 #include <vm/vm_map.h> 85 #include <vm/vm_object.h> 86 #include <vm/vm_page.h> 87 #include <vm/vm_pager.h> 88 #include <vm/swap_pager.h> 89 90 struct shm_mapping { 91 char *sm_path; 92 Fnv32_t sm_fnv; 93 struct shmfd *sm_shmfd; 94 LIST_ENTRY(shm_mapping) sm_link; 95 }; 96 97 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 98 static LIST_HEAD(, shm_mapping) *shm_dictionary; 99 static struct sx shm_dict_lock; 100 static struct mtx shm_timestamp_lock; 101 static u_long shm_hash; 102 103 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 104 105 static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags); 106 static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode); 107 static void shm_dict_init(void *arg); 108 static void shm_drop(struct shmfd *shmfd); 109 static struct shmfd *shm_hold(struct shmfd *shmfd); 110 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 111 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 112 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 113 static int shm_dotruncate(struct shmfd *shmfd, off_t length); 114 115 static fo_rdwr_t shm_read; 116 static fo_rdwr_t shm_write; 117 static fo_truncate_t shm_truncate; 118 static fo_ioctl_t shm_ioctl; 119 static fo_poll_t shm_poll; 120 static fo_kqfilter_t shm_kqfilter; 121 static fo_stat_t shm_stat; 122 static fo_close_t shm_close; 123 static fo_chmod_t shm_chmod; 124 static fo_chown_t shm_chown; 125 126 /* File descriptor operations. */ 127 static struct fileops shm_ops = { 128 .fo_read = shm_read, 129 .fo_write = shm_write, 130 .fo_truncate = shm_truncate, 131 .fo_ioctl = shm_ioctl, 132 .fo_poll = shm_poll, 133 .fo_kqfilter = shm_kqfilter, 134 .fo_stat = shm_stat, 135 .fo_close = shm_close, 136 .fo_chmod = shm_chmod, 137 .fo_chown = shm_chown, 138 .fo_flags = DFLAG_PASSABLE 139 }; 140 141 FEATURE(posix_shm, "POSIX shared memory"); 142 143 static int 144 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 145 int flags, struct thread *td) 146 { 147 148 return (EOPNOTSUPP); 149 } 150 151 static int 152 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 153 int flags, struct thread *td) 154 { 155 156 return (EOPNOTSUPP); 157 } 158 159 static int 160 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 161 struct thread *td) 162 { 163 struct shmfd *shmfd; 164 #ifdef MAC 165 int error; 166 #endif 167 168 shmfd = fp->f_data; 169 #ifdef MAC 170 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 171 if (error) 172 return (error); 173 #endif 174 return (shm_dotruncate(shmfd, length)); 175 } 176 177 static int 178 shm_ioctl(struct file *fp, u_long com, void *data, 179 struct ucred *active_cred, struct thread *td) 180 { 181 182 return (EOPNOTSUPP); 183 } 184 185 static int 186 shm_poll(struct file *fp, int events, struct ucred *active_cred, 187 struct thread *td) 188 { 189 190 return (EOPNOTSUPP); 191 } 192 193 static int 194 shm_kqfilter(struct file *fp, struct knote *kn) 195 { 196 197 return (EOPNOTSUPP); 198 } 199 200 static int 201 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 202 struct thread *td) 203 { 204 struct shmfd *shmfd; 205 #ifdef MAC 206 int error; 207 #endif 208 209 shmfd = fp->f_data; 210 211 #ifdef MAC 212 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 213 if (error) 214 return (error); 215 #endif 216 217 /* 218 * Attempt to return sanish values for fstat() on a memory file 219 * descriptor. 220 */ 221 bzero(sb, sizeof(*sb)); 222 sb->st_blksize = PAGE_SIZE; 223 sb->st_size = shmfd->shm_size; 224 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 225 mtx_lock(&shm_timestamp_lock); 226 sb->st_atim = shmfd->shm_atime; 227 sb->st_ctim = shmfd->shm_ctime; 228 sb->st_mtim = shmfd->shm_mtime; 229 sb->st_birthtim = shmfd->shm_birthtime; 230 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 231 sb->st_uid = shmfd->shm_uid; 232 sb->st_gid = shmfd->shm_gid; 233 mtx_unlock(&shm_timestamp_lock); 234 235 return (0); 236 } 237 238 static int 239 shm_close(struct file *fp, struct thread *td) 240 { 241 struct shmfd *shmfd; 242 243 shmfd = fp->f_data; 244 fp->f_data = NULL; 245 shm_drop(shmfd); 246 247 return (0); 248 } 249 250 static int 251 shm_dotruncate(struct shmfd *shmfd, off_t length) 252 { 253 vm_object_t object; 254 vm_page_t m; 255 vm_pindex_t nobjsize; 256 vm_ooffset_t delta; 257 258 object = shmfd->shm_object; 259 VM_OBJECT_LOCK(object); 260 if (length == shmfd->shm_size) { 261 VM_OBJECT_UNLOCK(object); 262 return (0); 263 } 264 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 265 266 /* Are we shrinking? If so, trim the end. */ 267 if (length < shmfd->shm_size) { 268 delta = ptoa(object->size - nobjsize); 269 270 /* Toss in memory pages. */ 271 if (nobjsize < object->size) 272 vm_object_page_remove(object, nobjsize, object->size, 273 0); 274 275 /* Toss pages from swap. */ 276 if (object->type == OBJT_SWAP) 277 swap_pager_freespace(object, nobjsize, delta); 278 279 /* Free the swap accounted for shm */ 280 swap_release_by_cred(delta, object->cred); 281 object->charge -= delta; 282 283 /* 284 * If the last page is partially mapped, then zero out 285 * the garbage at the end of the page. See comments 286 * in vnode_pager_setsize() for more details. 287 * 288 * XXXJHB: This handles in memory pages, but what about 289 * a page swapped out to disk? 290 */ 291 if ((length & PAGE_MASK) && 292 (m = vm_page_lookup(object, OFF_TO_IDX(length))) != NULL && 293 m->valid != 0) { 294 int base = (int)length & PAGE_MASK; 295 int size = PAGE_SIZE - base; 296 297 pmap_zero_page_area(m, base, size); 298 299 /* 300 * Update the valid bits to reflect the blocks that 301 * have been zeroed. Some of these valid bits may 302 * have already been set. 303 */ 304 vm_page_set_valid_range(m, base, size); 305 306 /* 307 * Round "base" to the next block boundary so that the 308 * dirty bit for a partially zeroed block is not 309 * cleared. 310 */ 311 base = roundup2(base, DEV_BSIZE); 312 313 vm_page_clear_dirty(m, base, PAGE_SIZE - base); 314 } else if ((length & PAGE_MASK) && 315 __predict_false(object->cache != NULL)) { 316 vm_page_cache_free(object, OFF_TO_IDX(length), 317 nobjsize); 318 } 319 } else { 320 321 /* Attempt to reserve the swap */ 322 delta = ptoa(nobjsize - object->size); 323 if (!swap_reserve_by_cred(delta, object->cred)) { 324 VM_OBJECT_UNLOCK(object); 325 return (ENOMEM); 326 } 327 object->charge += delta; 328 } 329 shmfd->shm_size = length; 330 mtx_lock(&shm_timestamp_lock); 331 vfs_timestamp(&shmfd->shm_ctime); 332 shmfd->shm_mtime = shmfd->shm_ctime; 333 mtx_unlock(&shm_timestamp_lock); 334 object->size = nobjsize; 335 VM_OBJECT_UNLOCK(object); 336 return (0); 337 } 338 339 /* 340 * shmfd object management including creation and reference counting 341 * routines. 342 */ 343 static struct shmfd * 344 shm_alloc(struct ucred *ucred, mode_t mode) 345 { 346 struct shmfd *shmfd; 347 348 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 349 shmfd->shm_size = 0; 350 shmfd->shm_uid = ucred->cr_uid; 351 shmfd->shm_gid = ucred->cr_gid; 352 shmfd->shm_mode = mode; 353 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 354 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 355 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 356 VM_OBJECT_LOCK(shmfd->shm_object); 357 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 358 vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT); 359 VM_OBJECT_UNLOCK(shmfd->shm_object); 360 vfs_timestamp(&shmfd->shm_birthtime); 361 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 362 shmfd->shm_birthtime; 363 refcount_init(&shmfd->shm_refs, 1); 364 #ifdef MAC 365 mac_posixshm_init(shmfd); 366 mac_posixshm_create(ucred, shmfd); 367 #endif 368 369 return (shmfd); 370 } 371 372 static struct shmfd * 373 shm_hold(struct shmfd *shmfd) 374 { 375 376 refcount_acquire(&shmfd->shm_refs); 377 return (shmfd); 378 } 379 380 static void 381 shm_drop(struct shmfd *shmfd) 382 { 383 384 if (refcount_release(&shmfd->shm_refs)) { 385 #ifdef MAC 386 mac_posixshm_destroy(shmfd); 387 #endif 388 vm_object_deallocate(shmfd->shm_object); 389 free(shmfd, M_SHMFD); 390 } 391 } 392 393 /* 394 * Determine if the credentials have sufficient permissions for a 395 * specified combination of FREAD and FWRITE. 396 */ 397 static int 398 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 399 { 400 accmode_t accmode; 401 int error; 402 403 accmode = 0; 404 if (flags & FREAD) 405 accmode |= VREAD; 406 if (flags & FWRITE) 407 accmode |= VWRITE; 408 mtx_lock(&shm_timestamp_lock); 409 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 410 accmode, ucred, NULL); 411 mtx_unlock(&shm_timestamp_lock); 412 return (error); 413 } 414 415 /* 416 * Dictionary management. We maintain an in-kernel dictionary to map 417 * paths to shmfd objects. We use the FNV hash on the path to store 418 * the mappings in a hash table. 419 */ 420 static void 421 shm_dict_init(void *arg) 422 { 423 424 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 425 sx_init(&shm_dict_lock, "shm dictionary"); 426 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 427 } 428 SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL); 429 430 static struct shmfd * 431 shm_lookup(char *path, Fnv32_t fnv) 432 { 433 struct shm_mapping *map; 434 435 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 436 if (map->sm_fnv != fnv) 437 continue; 438 if (strcmp(map->sm_path, path) == 0) 439 return (map->sm_shmfd); 440 } 441 442 return (NULL); 443 } 444 445 static void 446 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 447 { 448 struct shm_mapping *map; 449 450 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 451 map->sm_path = path; 452 map->sm_fnv = fnv; 453 map->sm_shmfd = shm_hold(shmfd); 454 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 455 } 456 457 static int 458 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 459 { 460 struct shm_mapping *map; 461 int error; 462 463 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 464 if (map->sm_fnv != fnv) 465 continue; 466 if (strcmp(map->sm_path, path) == 0) { 467 #ifdef MAC 468 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 469 if (error) 470 return (error); 471 #endif 472 error = shm_access(map->sm_shmfd, ucred, 473 FREAD | FWRITE); 474 if (error) 475 return (error); 476 LIST_REMOVE(map, sm_link); 477 shm_drop(map->sm_shmfd); 478 free(map->sm_path, M_SHMFD); 479 free(map, M_SHMFD); 480 return (0); 481 } 482 } 483 484 return (ENOENT); 485 } 486 487 /* System calls. */ 488 int 489 sys_shm_open(struct thread *td, struct shm_open_args *uap) 490 { 491 struct filedesc *fdp; 492 struct shmfd *shmfd; 493 struct file *fp; 494 char *path; 495 Fnv32_t fnv; 496 mode_t cmode; 497 int fd, error; 498 499 #ifdef CAPABILITY_MODE 500 /* 501 * shm_open(2) is only allowed for anonymous objects. 502 */ 503 if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 504 return (ECAPMODE); 505 #endif 506 507 if ((uap->flags & O_ACCMODE) != O_RDONLY && 508 (uap->flags & O_ACCMODE) != O_RDWR) 509 return (EINVAL); 510 511 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0) 512 return (EINVAL); 513 514 fdp = td->td_proc->p_fd; 515 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 516 517 error = falloc(td, &fp, &fd, 0); 518 if (error) 519 return (error); 520 521 /* A SHM_ANON path pointer creates an anonymous object. */ 522 if (uap->path == SHM_ANON) { 523 /* A read-only anonymous object is pointless. */ 524 if ((uap->flags & O_ACCMODE) == O_RDONLY) { 525 fdclose(fdp, fp, fd, td); 526 fdrop(fp, td); 527 return (EINVAL); 528 } 529 shmfd = shm_alloc(td->td_ucred, cmode); 530 } else { 531 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 532 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 533 534 /* Require paths to start with a '/' character. */ 535 if (error == 0 && path[0] != '/') 536 error = EINVAL; 537 if (error) { 538 fdclose(fdp, fp, fd, td); 539 fdrop(fp, td); 540 free(path, M_SHMFD); 541 return (error); 542 } 543 544 fnv = fnv_32_str(path, FNV1_32_INIT); 545 sx_xlock(&shm_dict_lock); 546 shmfd = shm_lookup(path, fnv); 547 if (shmfd == NULL) { 548 /* Object does not yet exist, create it if requested. */ 549 if (uap->flags & O_CREAT) { 550 #ifdef MAC 551 error = mac_posixshm_check_create(td->td_ucred, 552 path); 553 if (error == 0) { 554 #endif 555 shmfd = shm_alloc(td->td_ucred, cmode); 556 shm_insert(path, fnv, shmfd); 557 #ifdef MAC 558 } 559 #endif 560 } else { 561 free(path, M_SHMFD); 562 error = ENOENT; 563 } 564 } else { 565 /* 566 * Object already exists, obtain a new 567 * reference if requested and permitted. 568 */ 569 free(path, M_SHMFD); 570 if ((uap->flags & (O_CREAT | O_EXCL)) == 571 (O_CREAT | O_EXCL)) 572 error = EEXIST; 573 else { 574 #ifdef MAC 575 error = mac_posixshm_check_open(td->td_ucred, 576 shmfd, FFLAGS(uap->flags & O_ACCMODE)); 577 if (error == 0) 578 #endif 579 error = shm_access(shmfd, td->td_ucred, 580 FFLAGS(uap->flags & O_ACCMODE)); 581 } 582 583 /* 584 * Truncate the file back to zero length if 585 * O_TRUNC was specified and the object was 586 * opened with read/write. 587 */ 588 if (error == 0 && 589 (uap->flags & (O_ACCMODE | O_TRUNC)) == 590 (O_RDWR | O_TRUNC)) { 591 #ifdef MAC 592 error = mac_posixshm_check_truncate( 593 td->td_ucred, fp->f_cred, shmfd); 594 if (error == 0) 595 #endif 596 shm_dotruncate(shmfd, 0); 597 } 598 if (error == 0) 599 shm_hold(shmfd); 600 } 601 sx_xunlock(&shm_dict_lock); 602 603 if (error) { 604 fdclose(fdp, fp, fd, td); 605 fdrop(fp, td); 606 return (error); 607 } 608 } 609 610 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 611 612 FILEDESC_XLOCK(fdp); 613 if (fdp->fd_ofiles[fd] == fp) 614 fdp->fd_ofileflags[fd] |= UF_EXCLOSE; 615 FILEDESC_XUNLOCK(fdp); 616 td->td_retval[0] = fd; 617 fdrop(fp, td); 618 619 return (0); 620 } 621 622 int 623 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 624 { 625 char *path; 626 Fnv32_t fnv; 627 int error; 628 629 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 630 error = copyinstr(uap->path, path, MAXPATHLEN, NULL); 631 if (error) { 632 free(path, M_TEMP); 633 return (error); 634 } 635 636 fnv = fnv_32_str(path, FNV1_32_INIT); 637 sx_xlock(&shm_dict_lock); 638 error = shm_remove(path, fnv, td->td_ucred); 639 sx_xunlock(&shm_dict_lock); 640 free(path, M_TEMP); 641 642 return (error); 643 } 644 645 /* 646 * mmap() helper to validate mmap() requests against shm object state 647 * and give mmap() the vm_object to use for the mapping. 648 */ 649 int 650 shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff, 651 vm_object_t *obj) 652 { 653 654 /* 655 * XXXRW: This validation is probably insufficient, and subject to 656 * sign errors. It should be fixed. 657 */ 658 if (foff >= shmfd->shm_size || 659 foff + objsize > round_page(shmfd->shm_size)) 660 return (EINVAL); 661 662 mtx_lock(&shm_timestamp_lock); 663 vfs_timestamp(&shmfd->shm_atime); 664 mtx_unlock(&shm_timestamp_lock); 665 vm_object_reference(shmfd->shm_object); 666 *obj = shmfd->shm_object; 667 return (0); 668 } 669 670 static int 671 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 672 struct thread *td) 673 { 674 struct shmfd *shmfd; 675 int error; 676 677 error = 0; 678 shmfd = fp->f_data; 679 mtx_lock(&shm_timestamp_lock); 680 /* 681 * SUSv4 says that x bits of permission need not be affected. 682 * Be consistent with our shm_open there. 683 */ 684 #ifdef MAC 685 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 686 if (error != 0) 687 goto out; 688 #endif 689 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 690 shmfd->shm_gid, VADMIN, active_cred, NULL); 691 if (error != 0) 692 goto out; 693 shmfd->shm_mode = mode & ACCESSPERMS; 694 out: 695 mtx_unlock(&shm_timestamp_lock); 696 return (error); 697 } 698 699 static int 700 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 701 struct thread *td) 702 { 703 struct shmfd *shmfd; 704 int error; 705 706 error = 0; 707 shmfd = fp->f_data; 708 mtx_lock(&shm_timestamp_lock); 709 #ifdef MAC 710 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 711 if (error != 0) 712 goto out; 713 #endif 714 if (uid == (uid_t)-1) 715 uid = shmfd->shm_uid; 716 if (gid == (gid_t)-1) 717 gid = shmfd->shm_gid; 718 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 719 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 720 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 721 goto out; 722 shmfd->shm_uid = uid; 723 shmfd->shm_gid = gid; 724 out: 725 mtx_unlock(&shm_timestamp_lock); 726 return (error); 727 } 728