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 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_wire(m); 212 vm_page_unlock(m); 213 VM_OBJECT_WUNLOCK(obj); 214 error = uiomove_fromphys(&m, offset, tlen, uio); 215 if (uio->uio_rw == UIO_WRITE && error == 0) { 216 VM_OBJECT_WLOCK(obj); 217 vm_page_dirty(m); 218 vm_pager_page_unswapped(m); 219 VM_OBJECT_WUNLOCK(obj); 220 } 221 vm_page_lock(m); 222 vm_page_unwire(m, PQ_ACTIVE); 223 vm_page_unlock(m); 224 225 return (error); 226 } 227 228 int 229 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 230 { 231 ssize_t resid; 232 size_t len; 233 int error; 234 235 error = 0; 236 while ((resid = uio->uio_resid) > 0) { 237 if (obj_size <= uio->uio_offset) 238 break; 239 len = MIN(obj_size - uio->uio_offset, resid); 240 if (len == 0) 241 break; 242 error = uiomove_object_page(obj, len, uio); 243 if (error != 0 || resid == uio->uio_resid) 244 break; 245 } 246 return (error); 247 } 248 249 static int 250 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 251 { 252 struct shmfd *shmfd; 253 off_t foffset; 254 int error; 255 256 shmfd = fp->f_data; 257 foffset = foffset_lock(fp, 0); 258 error = 0; 259 switch (whence) { 260 case L_INCR: 261 if (foffset < 0 || 262 (offset > 0 && foffset > OFF_MAX - offset)) { 263 error = EOVERFLOW; 264 break; 265 } 266 offset += foffset; 267 break; 268 case L_XTND: 269 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 270 error = EOVERFLOW; 271 break; 272 } 273 offset += shmfd->shm_size; 274 break; 275 case L_SET: 276 break; 277 default: 278 error = EINVAL; 279 } 280 if (error == 0) { 281 if (offset < 0 || offset > shmfd->shm_size) 282 error = EINVAL; 283 else 284 td->td_uretoff.tdu_off = offset; 285 } 286 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 287 return (error); 288 } 289 290 static int 291 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 292 int flags, struct thread *td) 293 { 294 struct shmfd *shmfd; 295 void *rl_cookie; 296 int error; 297 298 shmfd = fp->f_data; 299 #ifdef MAC 300 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 301 if (error) 302 return (error); 303 #endif 304 foffset_lock_uio(fp, uio, flags); 305 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 306 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 307 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 308 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 309 foffset_unlock_uio(fp, uio, flags); 310 return (error); 311 } 312 313 static int 314 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 315 int flags, struct thread *td) 316 { 317 struct shmfd *shmfd; 318 void *rl_cookie; 319 int error; 320 321 shmfd = fp->f_data; 322 #ifdef MAC 323 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 324 if (error) 325 return (error); 326 #endif 327 foffset_lock_uio(fp, uio, flags); 328 if ((flags & FOF_OFFSET) == 0) { 329 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 330 &shmfd->shm_mtx); 331 } else { 332 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 333 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 334 } 335 336 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 337 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 338 foffset_unlock_uio(fp, uio, flags); 339 return (error); 340 } 341 342 static int 343 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 344 struct thread *td) 345 { 346 struct shmfd *shmfd; 347 #ifdef MAC 348 int error; 349 #endif 350 351 shmfd = fp->f_data; 352 #ifdef MAC 353 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 354 if (error) 355 return (error); 356 #endif 357 return (shm_dotruncate(shmfd, length)); 358 } 359 360 int 361 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 362 struct thread *td) 363 { 364 365 switch (com) { 366 case FIONBIO: 367 case FIOASYNC: 368 /* 369 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 370 * just like it would on an unlinked regular file 371 */ 372 return (0); 373 default: 374 return (ENOTTY); 375 } 376 } 377 378 static int 379 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 380 struct thread *td) 381 { 382 struct shmfd *shmfd; 383 #ifdef MAC 384 int error; 385 #endif 386 387 shmfd = fp->f_data; 388 389 #ifdef MAC 390 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 391 if (error) 392 return (error); 393 #endif 394 395 /* 396 * Attempt to return sanish values for fstat() on a memory file 397 * descriptor. 398 */ 399 bzero(sb, sizeof(*sb)); 400 sb->st_blksize = PAGE_SIZE; 401 sb->st_size = shmfd->shm_size; 402 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 403 mtx_lock(&shm_timestamp_lock); 404 sb->st_atim = shmfd->shm_atime; 405 sb->st_ctim = shmfd->shm_ctime; 406 sb->st_mtim = shmfd->shm_mtime; 407 sb->st_birthtim = shmfd->shm_birthtime; 408 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 409 sb->st_uid = shmfd->shm_uid; 410 sb->st_gid = shmfd->shm_gid; 411 mtx_unlock(&shm_timestamp_lock); 412 sb->st_dev = shm_dev_ino; 413 sb->st_ino = shmfd->shm_ino; 414 sb->st_nlink = shmfd->shm_object->ref_count; 415 416 return (0); 417 } 418 419 static int 420 shm_close(struct file *fp, struct thread *td) 421 { 422 struct shmfd *shmfd; 423 424 shmfd = fp->f_data; 425 fp->f_data = NULL; 426 shm_drop(shmfd); 427 428 return (0); 429 } 430 431 int 432 shm_dotruncate(struct shmfd *shmfd, off_t length) 433 { 434 vm_object_t object; 435 vm_page_t m; 436 vm_pindex_t idx, nobjsize; 437 vm_ooffset_t delta; 438 int base, rv; 439 440 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 441 object = shmfd->shm_object; 442 VM_OBJECT_WLOCK(object); 443 if (length == shmfd->shm_size) { 444 VM_OBJECT_WUNLOCK(object); 445 return (0); 446 } 447 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 448 449 /* Are we shrinking? If so, trim the end. */ 450 if (length < shmfd->shm_size) { 451 /* 452 * Disallow any requests to shrink the size if this 453 * object is mapped into the kernel. 454 */ 455 if (shmfd->shm_kmappings > 0) { 456 VM_OBJECT_WUNLOCK(object); 457 return (EBUSY); 458 } 459 460 /* 461 * Zero the truncated part of the last page. 462 */ 463 base = length & PAGE_MASK; 464 if (base != 0) { 465 idx = OFF_TO_IDX(length); 466 retry: 467 m = vm_page_lookup(object, idx); 468 if (m != NULL) { 469 if (vm_page_sleep_if_busy(m, "shmtrc")) 470 goto retry; 471 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 472 m = vm_page_alloc(object, idx, 473 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 474 if (m == NULL) 475 goto retry; 476 rv = vm_pager_get_pages(object, &m, 1, NULL, 477 NULL); 478 vm_page_lock(m); 479 if (rv == VM_PAGER_OK) { 480 /* 481 * Since the page was not resident, 482 * and therefore not recently 483 * accessed, immediately enqueue it 484 * for asynchronous laundering. The 485 * current operation is not regarded 486 * as an access. 487 */ 488 vm_page_launder(m); 489 vm_page_unlock(m); 490 vm_page_xunbusy(m); 491 } else { 492 vm_page_free(m); 493 vm_page_unlock(m); 494 VM_OBJECT_WUNLOCK(object); 495 return (EIO); 496 } 497 } 498 if (m != NULL) { 499 pmap_zero_page_area(m, base, PAGE_SIZE - base); 500 KASSERT(m->valid == VM_PAGE_BITS_ALL, 501 ("shm_dotruncate: page %p is invalid", m)); 502 vm_page_dirty(m); 503 vm_pager_page_unswapped(m); 504 } 505 } 506 delta = IDX_TO_OFF(object->size - nobjsize); 507 508 /* Toss in memory pages. */ 509 if (nobjsize < object->size) 510 vm_object_page_remove(object, nobjsize, object->size, 511 0); 512 513 /* Toss pages from swap. */ 514 if (object->type == OBJT_SWAP) 515 swap_pager_freespace(object, nobjsize, delta); 516 517 /* Free the swap accounted for shm */ 518 swap_release_by_cred(delta, object->cred); 519 object->charge -= delta; 520 } else { 521 /* Try to reserve additional swap space. */ 522 delta = IDX_TO_OFF(nobjsize - object->size); 523 if (!swap_reserve_by_cred(delta, object->cred)) { 524 VM_OBJECT_WUNLOCK(object); 525 return (ENOMEM); 526 } 527 object->charge += delta; 528 } 529 shmfd->shm_size = length; 530 mtx_lock(&shm_timestamp_lock); 531 vfs_timestamp(&shmfd->shm_ctime); 532 shmfd->shm_mtime = shmfd->shm_ctime; 533 mtx_unlock(&shm_timestamp_lock); 534 object->size = nobjsize; 535 VM_OBJECT_WUNLOCK(object); 536 return (0); 537 } 538 539 /* 540 * shmfd object management including creation and reference counting 541 * routines. 542 */ 543 struct shmfd * 544 shm_alloc(struct ucred *ucred, mode_t mode) 545 { 546 struct shmfd *shmfd; 547 548 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 549 shmfd->shm_size = 0; 550 shmfd->shm_uid = ucred->cr_uid; 551 shmfd->shm_gid = ucred->cr_gid; 552 shmfd->shm_mode = mode; 553 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 554 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 555 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 556 shmfd->shm_object->pg_color = 0; 557 VM_OBJECT_WLOCK(shmfd->shm_object); 558 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 559 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 560 VM_OBJECT_WUNLOCK(shmfd->shm_object); 561 vfs_timestamp(&shmfd->shm_birthtime); 562 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 563 shmfd->shm_birthtime; 564 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 565 refcount_init(&shmfd->shm_refs, 1); 566 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 567 rangelock_init(&shmfd->shm_rl); 568 #ifdef MAC 569 mac_posixshm_init(shmfd); 570 mac_posixshm_create(ucred, shmfd); 571 #endif 572 573 return (shmfd); 574 } 575 576 struct shmfd * 577 shm_hold(struct shmfd *shmfd) 578 { 579 580 refcount_acquire(&shmfd->shm_refs); 581 return (shmfd); 582 } 583 584 void 585 shm_drop(struct shmfd *shmfd) 586 { 587 588 if (refcount_release(&shmfd->shm_refs)) { 589 #ifdef MAC 590 mac_posixshm_destroy(shmfd); 591 #endif 592 rangelock_destroy(&shmfd->shm_rl); 593 mtx_destroy(&shmfd->shm_mtx); 594 vm_object_deallocate(shmfd->shm_object); 595 free(shmfd, M_SHMFD); 596 } 597 } 598 599 /* 600 * Determine if the credentials have sufficient permissions for a 601 * specified combination of FREAD and FWRITE. 602 */ 603 int 604 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 605 { 606 accmode_t accmode; 607 int error; 608 609 accmode = 0; 610 if (flags & FREAD) 611 accmode |= VREAD; 612 if (flags & FWRITE) 613 accmode |= VWRITE; 614 mtx_lock(&shm_timestamp_lock); 615 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 616 accmode, ucred, NULL); 617 mtx_unlock(&shm_timestamp_lock); 618 return (error); 619 } 620 621 /* 622 * Dictionary management. We maintain an in-kernel dictionary to map 623 * paths to shmfd objects. We use the FNV hash on the path to store 624 * the mappings in a hash table. 625 */ 626 static void 627 shm_init(void *arg) 628 { 629 630 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 631 sx_init(&shm_dict_lock, "shm dictionary"); 632 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 633 new_unrhdr64(&shm_ino_unr, 1); 634 shm_dev_ino = devfs_alloc_cdp_inode(); 635 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 636 } 637 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 638 639 static struct shmfd * 640 shm_lookup(char *path, Fnv32_t fnv) 641 { 642 struct shm_mapping *map; 643 644 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 645 if (map->sm_fnv != fnv) 646 continue; 647 if (strcmp(map->sm_path, path) == 0) 648 return (map->sm_shmfd); 649 } 650 651 return (NULL); 652 } 653 654 static void 655 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 656 { 657 struct shm_mapping *map; 658 659 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 660 map->sm_path = path; 661 map->sm_fnv = fnv; 662 map->sm_shmfd = shm_hold(shmfd); 663 shmfd->shm_path = path; 664 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 665 } 666 667 static int 668 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 669 { 670 struct shm_mapping *map; 671 int error; 672 673 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 674 if (map->sm_fnv != fnv) 675 continue; 676 if (strcmp(map->sm_path, path) == 0) { 677 #ifdef MAC 678 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 679 if (error) 680 return (error); 681 #endif 682 error = shm_access(map->sm_shmfd, ucred, 683 FREAD | FWRITE); 684 if (error) 685 return (error); 686 map->sm_shmfd->shm_path = NULL; 687 LIST_REMOVE(map, sm_link); 688 shm_drop(map->sm_shmfd); 689 free(map->sm_path, M_SHMFD); 690 free(map, M_SHMFD); 691 return (0); 692 } 693 } 694 695 return (ENOENT); 696 } 697 698 int 699 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode, 700 struct filecaps *fcaps) 701 { 702 struct filedesc *fdp; 703 struct shmfd *shmfd; 704 struct file *fp; 705 char *path; 706 const char *pr_path; 707 size_t pr_pathlen; 708 Fnv32_t fnv; 709 mode_t cmode; 710 int fd, error; 711 712 #ifdef CAPABILITY_MODE 713 /* 714 * shm_open(2) is only allowed for anonymous objects. 715 */ 716 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 717 return (ECAPMODE); 718 #endif 719 720 AUDIT_ARG_FFLAGS(flags); 721 AUDIT_ARG_MODE(mode); 722 723 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 724 return (EINVAL); 725 726 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 727 return (EINVAL); 728 729 fdp = td->td_proc->p_fd; 730 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 731 732 /* 733 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 734 * by POSIX. We allow it to be unset here so that an in-kernel 735 * interface may be written as a thin layer around shm, optionally not 736 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 737 * in sys_shm_open() to keep this implementation compliant. 738 */ 739 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 740 if (error) 741 return (error); 742 743 /* A SHM_ANON path pointer creates an anonymous object. */ 744 if (userpath == SHM_ANON) { 745 /* A read-only anonymous object is pointless. */ 746 if ((flags & O_ACCMODE) == O_RDONLY) { 747 fdclose(td, fp, fd); 748 fdrop(fp, td); 749 return (EINVAL); 750 } 751 shmfd = shm_alloc(td->td_ucred, cmode); 752 } else { 753 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 754 pr_path = td->td_ucred->cr_prison->pr_path; 755 756 /* Construct a full pathname for jailed callers. */ 757 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 758 : strlcpy(path, pr_path, MAXPATHLEN); 759 error = copyinstr(userpath, path + pr_pathlen, 760 MAXPATHLEN - pr_pathlen, NULL); 761 #ifdef KTRACE 762 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 763 ktrnamei(path); 764 #endif 765 /* Require paths to start with a '/' character. */ 766 if (error == 0 && path[pr_pathlen] != '/') 767 error = EINVAL; 768 if (error) { 769 fdclose(td, fp, fd); 770 fdrop(fp, td); 771 free(path, M_SHMFD); 772 return (error); 773 } 774 775 AUDIT_ARG_UPATH1_CANON(path); 776 fnv = fnv_32_str(path, FNV1_32_INIT); 777 sx_xlock(&shm_dict_lock); 778 shmfd = shm_lookup(path, fnv); 779 if (shmfd == NULL) { 780 /* Object does not yet exist, create it if requested. */ 781 if (flags & O_CREAT) { 782 #ifdef MAC 783 error = mac_posixshm_check_create(td->td_ucred, 784 path); 785 if (error == 0) { 786 #endif 787 shmfd = shm_alloc(td->td_ucred, cmode); 788 shm_insert(path, fnv, shmfd); 789 #ifdef MAC 790 } 791 #endif 792 } else { 793 free(path, M_SHMFD); 794 error = ENOENT; 795 } 796 } else { 797 /* 798 * Object already exists, obtain a new 799 * reference if requested and permitted. 800 */ 801 free(path, M_SHMFD); 802 if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) 803 error = EEXIST; 804 else { 805 #ifdef MAC 806 error = mac_posixshm_check_open(td->td_ucred, 807 shmfd, FFLAGS(flags & O_ACCMODE)); 808 if (error == 0) 809 #endif 810 error = shm_access(shmfd, td->td_ucred, 811 FFLAGS(flags & O_ACCMODE)); 812 } 813 814 /* 815 * Truncate the file back to zero length if 816 * O_TRUNC was specified and the object was 817 * opened with read/write. 818 */ 819 if (error == 0 && 820 (flags & (O_ACCMODE | O_TRUNC)) == 821 (O_RDWR | O_TRUNC)) { 822 #ifdef MAC 823 error = mac_posixshm_check_truncate( 824 td->td_ucred, fp->f_cred, shmfd); 825 if (error == 0) 826 #endif 827 shm_dotruncate(shmfd, 0); 828 } 829 if (error == 0) 830 shm_hold(shmfd); 831 } 832 sx_xunlock(&shm_dict_lock); 833 834 if (error) { 835 fdclose(td, fp, fd); 836 fdrop(fp, td); 837 return (error); 838 } 839 } 840 841 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 842 843 td->td_retval[0] = fd; 844 fdrop(fp, td); 845 846 return (0); 847 } 848 849 /* System calls. */ 850 int 851 sys_shm_open(struct thread *td, struct shm_open_args *uap) 852 { 853 854 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, uap->mode, 855 NULL)); 856 } 857 858 int 859 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 860 { 861 char *path; 862 const char *pr_path; 863 size_t pr_pathlen; 864 Fnv32_t fnv; 865 int error; 866 867 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 868 pr_path = td->td_ucred->cr_prison->pr_path; 869 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 870 : strlcpy(path, pr_path, MAXPATHLEN); 871 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 872 NULL); 873 if (error) { 874 free(path, M_TEMP); 875 return (error); 876 } 877 #ifdef KTRACE 878 if (KTRPOINT(curthread, KTR_NAMEI)) 879 ktrnamei(path); 880 #endif 881 AUDIT_ARG_UPATH1_CANON(path); 882 fnv = fnv_32_str(path, FNV1_32_INIT); 883 sx_xlock(&shm_dict_lock); 884 error = shm_remove(path, fnv, td->td_ucred); 885 sx_xunlock(&shm_dict_lock); 886 free(path, M_TEMP); 887 888 return (error); 889 } 890 891 int 892 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 893 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 894 vm_ooffset_t foff, struct thread *td) 895 { 896 struct shmfd *shmfd; 897 vm_prot_t maxprot; 898 int error; 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 /* Don't permit shared writable mappings on read-only descriptors. */ 910 if ((flags & MAP_SHARED) != 0 && 911 (maxprot & VM_PROT_WRITE) == 0 && 912 (prot & 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 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 936 shmfd->shm_object, foff, FALSE, td); 937 if (error != 0) 938 vm_object_deallocate(shmfd->shm_object); 939 return (error); 940 } 941 942 static int 943 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 944 struct thread *td) 945 { 946 struct shmfd *shmfd; 947 int error; 948 949 error = 0; 950 shmfd = fp->f_data; 951 mtx_lock(&shm_timestamp_lock); 952 /* 953 * SUSv4 says that x bits of permission need not be affected. 954 * Be consistent with our shm_open there. 955 */ 956 #ifdef MAC 957 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 958 if (error != 0) 959 goto out; 960 #endif 961 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 962 shmfd->shm_gid, VADMIN, active_cred, NULL); 963 if (error != 0) 964 goto out; 965 shmfd->shm_mode = mode & ACCESSPERMS; 966 out: 967 mtx_unlock(&shm_timestamp_lock); 968 return (error); 969 } 970 971 static int 972 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 973 struct thread *td) 974 { 975 struct shmfd *shmfd; 976 int error; 977 978 error = 0; 979 shmfd = fp->f_data; 980 mtx_lock(&shm_timestamp_lock); 981 #ifdef MAC 982 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 983 if (error != 0) 984 goto out; 985 #endif 986 if (uid == (uid_t)-1) 987 uid = shmfd->shm_uid; 988 if (gid == (gid_t)-1) 989 gid = shmfd->shm_gid; 990 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 991 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 992 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 993 goto out; 994 shmfd->shm_uid = uid; 995 shmfd->shm_gid = gid; 996 out: 997 mtx_unlock(&shm_timestamp_lock); 998 return (error); 999 } 1000 1001 /* 1002 * Helper routines to allow the backing object of a shared memory file 1003 * descriptor to be mapped in the kernel. 1004 */ 1005 int 1006 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1007 { 1008 struct shmfd *shmfd; 1009 vm_offset_t kva, ofs; 1010 vm_object_t obj; 1011 int rv; 1012 1013 if (fp->f_type != DTYPE_SHM) 1014 return (EINVAL); 1015 shmfd = fp->f_data; 1016 obj = shmfd->shm_object; 1017 VM_OBJECT_WLOCK(obj); 1018 /* 1019 * XXXRW: This validation is probably insufficient, and subject to 1020 * sign errors. It should be fixed. 1021 */ 1022 if (offset >= shmfd->shm_size || 1023 offset + size > round_page(shmfd->shm_size)) { 1024 VM_OBJECT_WUNLOCK(obj); 1025 return (EINVAL); 1026 } 1027 1028 shmfd->shm_kmappings++; 1029 vm_object_reference_locked(obj); 1030 VM_OBJECT_WUNLOCK(obj); 1031 1032 /* Map the object into the kernel_map and wire it. */ 1033 kva = vm_map_min(kernel_map); 1034 ofs = offset & PAGE_MASK; 1035 offset = trunc_page(offset); 1036 size = round_page(size + ofs); 1037 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1038 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1039 VM_PROT_READ | VM_PROT_WRITE, 0); 1040 if (rv == KERN_SUCCESS) { 1041 rv = vm_map_wire(kernel_map, kva, kva + size, 1042 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1043 if (rv == KERN_SUCCESS) { 1044 *memp = (void *)(kva + ofs); 1045 return (0); 1046 } 1047 vm_map_remove(kernel_map, kva, kva + size); 1048 } else 1049 vm_object_deallocate(obj); 1050 1051 /* On failure, drop our mapping reference. */ 1052 VM_OBJECT_WLOCK(obj); 1053 shmfd->shm_kmappings--; 1054 VM_OBJECT_WUNLOCK(obj); 1055 1056 return (vm_mmap_to_errno(rv)); 1057 } 1058 1059 /* 1060 * We require the caller to unmap the entire entry. This allows us to 1061 * safely decrement shm_kmappings when a mapping is removed. 1062 */ 1063 int 1064 shm_unmap(struct file *fp, void *mem, size_t size) 1065 { 1066 struct shmfd *shmfd; 1067 vm_map_entry_t entry; 1068 vm_offset_t kva, ofs; 1069 vm_object_t obj; 1070 vm_pindex_t pindex; 1071 vm_prot_t prot; 1072 boolean_t wired; 1073 vm_map_t map; 1074 int rv; 1075 1076 if (fp->f_type != DTYPE_SHM) 1077 return (EINVAL); 1078 shmfd = fp->f_data; 1079 kva = (vm_offset_t)mem; 1080 ofs = kva & PAGE_MASK; 1081 kva = trunc_page(kva); 1082 size = round_page(size + ofs); 1083 map = kernel_map; 1084 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1085 &obj, &pindex, &prot, &wired); 1086 if (rv != KERN_SUCCESS) 1087 return (EINVAL); 1088 if (entry->start != kva || entry->end != kva + size) { 1089 vm_map_lookup_done(map, entry); 1090 return (EINVAL); 1091 } 1092 vm_map_lookup_done(map, entry); 1093 if (obj != shmfd->shm_object) 1094 return (EINVAL); 1095 vm_map_remove(map, kva, kva + size); 1096 VM_OBJECT_WLOCK(obj); 1097 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1098 shmfd->shm_kmappings--; 1099 VM_OBJECT_WUNLOCK(obj); 1100 return (0); 1101 } 1102 1103 static int 1104 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1105 { 1106 const char *path, *pr_path; 1107 size_t pr_pathlen; 1108 bool visible; 1109 1110 sx_assert(&shm_dict_lock, SA_LOCKED); 1111 kif->kf_type = KF_TYPE_SHM; 1112 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1113 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1114 if (shmfd->shm_path != NULL) { 1115 if (shmfd->shm_path != NULL) { 1116 path = shmfd->shm_path; 1117 pr_path = curthread->td_ucred->cr_prison->pr_path; 1118 if (strcmp(pr_path, "/") != 0) { 1119 /* Return the jail-rooted pathname. */ 1120 pr_pathlen = strlen(pr_path); 1121 visible = strncmp(path, pr_path, pr_pathlen) 1122 == 0 && path[pr_pathlen] == '/'; 1123 if (list && !visible) 1124 return (EPERM); 1125 if (visible) 1126 path += pr_pathlen; 1127 } 1128 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1129 } 1130 } 1131 return (0); 1132 } 1133 1134 static int 1135 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1136 struct filedesc *fdp __unused) 1137 { 1138 int res; 1139 1140 sx_slock(&shm_dict_lock); 1141 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1142 sx_sunlock(&shm_dict_lock); 1143 return (res); 1144 } 1145 1146 static int 1147 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1148 { 1149 struct shm_mapping *shmm; 1150 struct sbuf sb; 1151 struct kinfo_file kif; 1152 u_long i; 1153 ssize_t curlen; 1154 int error, error2; 1155 1156 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1157 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1158 curlen = 0; 1159 error = 0; 1160 sx_slock(&shm_dict_lock); 1161 for (i = 0; i < shm_hash + 1; i++) { 1162 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1163 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1164 &kif, true); 1165 if (error == EPERM) 1166 continue; 1167 if (error != 0) 1168 break; 1169 pack_kinfo(&kif); 1170 if (req->oldptr != NULL && 1171 kif.kf_structsize + curlen > req->oldlen) 1172 break; 1173 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1174 0 : ENOMEM; 1175 if (error != 0) 1176 break; 1177 curlen += kif.kf_structsize; 1178 } 1179 } 1180 sx_sunlock(&shm_dict_lock); 1181 error2 = sbuf_finish(&sb); 1182 sbuf_delete(&sb); 1183 return (error != 0 ? error : error2); 1184 } 1185 1186 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1187 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1188 NULL, 0, sysctl_posix_shm_list, "", 1189 "POSIX SHM list"); 1190