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