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), shm_rename(2), and shm_unlink(2). 37 * While most of the implementation is here, vm_mmap.c contains 38 * mapping logic changes. 39 * 40 * posixshmcontrol(1) allows users to inspect the state of the memory 41 * objects. Per-uid swap resource limit controls total amount of 42 * memory that user can consume for anonymous objects, including 43 * shared. 44 */ 45 46 #include <sys/cdefs.h> 47 __FBSDID("$FreeBSD$"); 48 49 #include "opt_capsicum.h" 50 #include "opt_ktrace.h" 51 52 #include <sys/param.h> 53 #include <sys/capsicum.h> 54 #include <sys/conf.h> 55 #include <sys/fcntl.h> 56 #include <sys/file.h> 57 #include <sys/filedesc.h> 58 #include <sys/filio.h> 59 #include <sys/fnv_hash.h> 60 #include <sys/kernel.h> 61 #include <sys/limits.h> 62 #include <sys/uio.h> 63 #include <sys/signal.h> 64 #include <sys/jail.h> 65 #include <sys/ktrace.h> 66 #include <sys/lock.h> 67 #include <sys/malloc.h> 68 #include <sys/mman.h> 69 #include <sys/mutex.h> 70 #include <sys/priv.h> 71 #include <sys/proc.h> 72 #include <sys/refcount.h> 73 #include <sys/resourcevar.h> 74 #include <sys/rwlock.h> 75 #include <sys/sbuf.h> 76 #include <sys/stat.h> 77 #include <sys/syscallsubr.h> 78 #include <sys/sysctl.h> 79 #include <sys/sysproto.h> 80 #include <sys/systm.h> 81 #include <sys/sx.h> 82 #include <sys/time.h> 83 #include <sys/vnode.h> 84 #include <sys/unistd.h> 85 #include <sys/user.h> 86 87 #include <security/audit/audit.h> 88 #include <security/mac/mac_framework.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_extern.h> 94 #include <vm/vm_map.h> 95 #include <vm/vm_kern.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_page.h> 98 #include <vm/vm_pageout.h> 99 #include <vm/vm_pager.h> 100 #include <vm/swap_pager.h> 101 102 struct shm_mapping { 103 char *sm_path; 104 Fnv32_t sm_fnv; 105 struct shmfd *sm_shmfd; 106 LIST_ENTRY(shm_mapping) sm_link; 107 }; 108 109 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 110 static LIST_HEAD(, shm_mapping) *shm_dictionary; 111 static struct sx shm_dict_lock; 112 static struct mtx shm_timestamp_lock; 113 static u_long shm_hash; 114 static struct unrhdr64 shm_ino_unr; 115 static dev_t shm_dev_ino; 116 117 #define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 118 119 static void shm_init(void *arg); 120 static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 121 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 122 static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 123 static int shm_dotruncate_locked(struct shmfd *shmfd, off_t length, 124 void *rl_cookie); 125 static int shm_copyin_path(struct thread *td, const char *userpath_in, 126 char **path_out); 127 128 static fo_rdwr_t shm_read; 129 static fo_rdwr_t shm_write; 130 static fo_truncate_t shm_truncate; 131 static fo_ioctl_t shm_ioctl; 132 static fo_stat_t shm_stat; 133 static fo_close_t shm_close; 134 static fo_chmod_t shm_chmod; 135 static fo_chown_t shm_chown; 136 static fo_seek_t shm_seek; 137 static fo_fill_kinfo_t shm_fill_kinfo; 138 static fo_mmap_t shm_mmap; 139 static fo_get_seals_t shm_get_seals; 140 static fo_add_seals_t shm_add_seals; 141 142 /* File descriptor operations. */ 143 struct fileops shm_ops = { 144 .fo_read = shm_read, 145 .fo_write = shm_write, 146 .fo_truncate = shm_truncate, 147 .fo_ioctl = shm_ioctl, 148 .fo_poll = invfo_poll, 149 .fo_kqfilter = invfo_kqfilter, 150 .fo_stat = shm_stat, 151 .fo_close = shm_close, 152 .fo_chmod = shm_chmod, 153 .fo_chown = shm_chown, 154 .fo_sendfile = vn_sendfile, 155 .fo_seek = shm_seek, 156 .fo_fill_kinfo = shm_fill_kinfo, 157 .fo_mmap = shm_mmap, 158 .fo_get_seals = shm_get_seals, 159 .fo_add_seals = shm_add_seals, 160 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 161 }; 162 163 FEATURE(posix_shm, "POSIX shared memory"); 164 165 static int 166 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 167 { 168 vm_page_t m; 169 vm_pindex_t idx; 170 size_t tlen; 171 int error, offset, rv; 172 173 idx = OFF_TO_IDX(uio->uio_offset); 174 offset = uio->uio_offset & PAGE_MASK; 175 tlen = MIN(PAGE_SIZE - offset, len); 176 177 VM_OBJECT_WLOCK(obj); 178 179 /* 180 * Read I/O without either a corresponding resident page or swap 181 * page: use zero_region. This is intended to avoid instantiating 182 * pages on read from a sparse region. 183 */ 184 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 185 !vm_pager_has_page(obj, idx, NULL, NULL)) { 186 VM_OBJECT_WUNLOCK(obj); 187 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 188 } 189 190 /* 191 * Parallel reads of the page content from disk are prevented 192 * by exclusive busy. 193 * 194 * Although the tmpfs vnode lock is held here, it is 195 * nonetheless safe to sleep waiting for a free page. The 196 * pageout daemon does not need to acquire the tmpfs vnode 197 * lock to page out tobj's pages because tobj is a OBJT_SWAP 198 * type object. 199 */ 200 rv = vm_page_grab_valid(&m, obj, idx, 201 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 202 if (rv != VM_PAGER_OK) { 203 VM_OBJECT_WUNLOCK(obj); 204 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 205 obj, idx, rv); 206 return (EIO); 207 } 208 VM_OBJECT_WUNLOCK(obj); 209 error = uiomove_fromphys(&m, offset, tlen, uio); 210 if (uio->uio_rw == UIO_WRITE && error == 0) 211 vm_page_set_dirty(m); 212 vm_page_activate(m); 213 vm_page_sunbusy(m); 214 215 return (error); 216 } 217 218 int 219 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 220 { 221 ssize_t resid; 222 size_t len; 223 int error; 224 225 error = 0; 226 while ((resid = uio->uio_resid) > 0) { 227 if (obj_size <= uio->uio_offset) 228 break; 229 len = MIN(obj_size - uio->uio_offset, resid); 230 if (len == 0) 231 break; 232 error = uiomove_object_page(obj, len, uio); 233 if (error != 0 || resid == uio->uio_resid) 234 break; 235 } 236 return (error); 237 } 238 239 static int 240 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 241 { 242 struct shmfd *shmfd; 243 off_t foffset; 244 int error; 245 246 shmfd = fp->f_data; 247 foffset = foffset_lock(fp, 0); 248 error = 0; 249 switch (whence) { 250 case L_INCR: 251 if (foffset < 0 || 252 (offset > 0 && foffset > OFF_MAX - offset)) { 253 error = EOVERFLOW; 254 break; 255 } 256 offset += foffset; 257 break; 258 case L_XTND: 259 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 260 error = EOVERFLOW; 261 break; 262 } 263 offset += shmfd->shm_size; 264 break; 265 case L_SET: 266 break; 267 default: 268 error = EINVAL; 269 } 270 if (error == 0) { 271 if (offset < 0 || offset > shmfd->shm_size) 272 error = EINVAL; 273 else 274 td->td_uretoff.tdu_off = offset; 275 } 276 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 277 return (error); 278 } 279 280 static int 281 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 282 int flags, struct thread *td) 283 { 284 struct shmfd *shmfd; 285 void *rl_cookie; 286 int error; 287 288 shmfd = fp->f_data; 289 #ifdef MAC 290 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 291 if (error) 292 return (error); 293 #endif 294 foffset_lock_uio(fp, uio, flags); 295 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 296 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 297 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 298 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 299 foffset_unlock_uio(fp, uio, flags); 300 return (error); 301 } 302 303 static int 304 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 305 int flags, struct thread *td) 306 { 307 struct shmfd *shmfd; 308 void *rl_cookie; 309 int error; 310 311 shmfd = fp->f_data; 312 #ifdef MAC 313 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 314 if (error) 315 return (error); 316 #endif 317 foffset_lock_uio(fp, uio, flags); 318 if ((flags & FOF_OFFSET) == 0) { 319 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 320 &shmfd->shm_mtx); 321 } else { 322 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 323 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 324 } 325 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) 326 error = EPERM; 327 else 328 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 329 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 330 foffset_unlock_uio(fp, uio, flags); 331 return (error); 332 } 333 334 static int 335 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 336 struct thread *td) 337 { 338 struct shmfd *shmfd; 339 #ifdef MAC 340 int error; 341 #endif 342 343 shmfd = fp->f_data; 344 #ifdef MAC 345 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 346 if (error) 347 return (error); 348 #endif 349 return (shm_dotruncate(shmfd, length)); 350 } 351 352 int 353 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 354 struct thread *td) 355 { 356 357 switch (com) { 358 case FIONBIO: 359 case FIOASYNC: 360 /* 361 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 362 * just like it would on an unlinked regular file 363 */ 364 return (0); 365 default: 366 return (ENOTTY); 367 } 368 } 369 370 static int 371 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 372 struct thread *td) 373 { 374 struct shmfd *shmfd; 375 #ifdef MAC 376 int error; 377 #endif 378 379 shmfd = fp->f_data; 380 381 #ifdef MAC 382 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 383 if (error) 384 return (error); 385 #endif 386 387 /* 388 * Attempt to return sanish values for fstat() on a memory file 389 * descriptor. 390 */ 391 bzero(sb, sizeof(*sb)); 392 sb->st_blksize = PAGE_SIZE; 393 sb->st_size = shmfd->shm_size; 394 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 395 mtx_lock(&shm_timestamp_lock); 396 sb->st_atim = shmfd->shm_atime; 397 sb->st_ctim = shmfd->shm_ctime; 398 sb->st_mtim = shmfd->shm_mtime; 399 sb->st_birthtim = shmfd->shm_birthtime; 400 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 401 sb->st_uid = shmfd->shm_uid; 402 sb->st_gid = shmfd->shm_gid; 403 mtx_unlock(&shm_timestamp_lock); 404 sb->st_dev = shm_dev_ino; 405 sb->st_ino = shmfd->shm_ino; 406 sb->st_nlink = shmfd->shm_object->ref_count; 407 408 return (0); 409 } 410 411 static int 412 shm_close(struct file *fp, struct thread *td) 413 { 414 struct shmfd *shmfd; 415 416 shmfd = fp->f_data; 417 fp->f_data = NULL; 418 shm_drop(shmfd); 419 420 return (0); 421 } 422 423 static int 424 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 425 int error; 426 char *path; 427 const char *pr_path; 428 size_t pr_pathlen; 429 430 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 431 pr_path = td->td_ucred->cr_prison->pr_path; 432 433 /* Construct a full pathname for jailed callers. */ 434 pr_pathlen = strcmp(pr_path, "/") == 435 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 436 error = copyinstr(userpath_in, path + pr_pathlen, 437 MAXPATHLEN - pr_pathlen, NULL); 438 if (error != 0) 439 goto out; 440 441 #ifdef KTRACE 442 if (KTRPOINT(curthread, KTR_NAMEI)) 443 ktrnamei(path); 444 #endif 445 446 /* Require paths to start with a '/' character. */ 447 if (path[pr_pathlen] != '/') { 448 error = EINVAL; 449 goto out; 450 } 451 452 *path_out = path; 453 454 out: 455 if (error != 0) 456 free(path, M_SHMFD); 457 458 return (error); 459 } 460 461 static int 462 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 463 { 464 vm_object_t object; 465 vm_page_t m; 466 vm_pindex_t idx, nobjsize; 467 vm_ooffset_t delta; 468 int base, rv; 469 470 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 471 object = shmfd->shm_object; 472 VM_OBJECT_ASSERT_WLOCKED(object); 473 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 474 if (length == shmfd->shm_size) 475 return (0); 476 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 477 478 /* Are we shrinking? If so, trim the end. */ 479 if (length < shmfd->shm_size) { 480 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 481 return (EPERM); 482 483 /* 484 * Disallow any requests to shrink the size if this 485 * object is mapped into the kernel. 486 */ 487 if (shmfd->shm_kmappings > 0) 488 return (EBUSY); 489 490 /* 491 * Zero the truncated part of the last page. 492 */ 493 base = length & PAGE_MASK; 494 if (base != 0) { 495 idx = OFF_TO_IDX(length); 496 retry: 497 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 498 if (m != NULL) { 499 MPASS(vm_page_all_valid(m)); 500 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 501 m = vm_page_alloc(object, idx, 502 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 503 if (m == NULL) 504 goto retry; 505 rv = vm_pager_get_pages(object, &m, 1, NULL, 506 NULL); 507 if (rv == VM_PAGER_OK) { 508 /* 509 * Since the page was not resident, 510 * and therefore not recently 511 * accessed, immediately enqueue it 512 * for asynchronous laundering. The 513 * current operation is not regarded 514 * as an access. 515 */ 516 vm_page_launder(m); 517 } else { 518 vm_page_free(m); 519 VM_OBJECT_WUNLOCK(object); 520 return (EIO); 521 } 522 } 523 if (m != NULL) { 524 pmap_zero_page_area(m, base, PAGE_SIZE - base); 525 KASSERT(vm_page_all_valid(m), 526 ("shm_dotruncate: page %p is invalid", m)); 527 vm_page_set_dirty(m); 528 vm_page_xunbusy(m); 529 } 530 } 531 delta = IDX_TO_OFF(object->size - nobjsize); 532 533 /* Toss in memory pages. */ 534 if (nobjsize < object->size) 535 vm_object_page_remove(object, nobjsize, object->size, 536 0); 537 538 /* Toss pages from swap. */ 539 if (object->type == OBJT_SWAP) 540 swap_pager_freespace(object, nobjsize, delta); 541 542 /* Free the swap accounted for shm */ 543 swap_release_by_cred(delta, object->cred); 544 object->charge -= delta; 545 } else { 546 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 547 return (EPERM); 548 549 /* Try to reserve additional swap space. */ 550 delta = IDX_TO_OFF(nobjsize - object->size); 551 if (!swap_reserve_by_cred(delta, object->cred)) 552 return (ENOMEM); 553 object->charge += delta; 554 } 555 shmfd->shm_size = length; 556 mtx_lock(&shm_timestamp_lock); 557 vfs_timestamp(&shmfd->shm_ctime); 558 shmfd->shm_mtime = shmfd->shm_ctime; 559 mtx_unlock(&shm_timestamp_lock); 560 object->size = nobjsize; 561 return (0); 562 } 563 564 int 565 shm_dotruncate(struct shmfd *shmfd, off_t length) 566 { 567 void *rl_cookie; 568 int error; 569 570 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 571 &shmfd->shm_mtx); 572 VM_OBJECT_WLOCK(shmfd->shm_object); 573 error = shm_dotruncate_locked(shmfd, length, rl_cookie); 574 VM_OBJECT_WUNLOCK(shmfd->shm_object); 575 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 576 return (error); 577 } 578 579 /* 580 * shmfd object management including creation and reference counting 581 * routines. 582 */ 583 struct shmfd * 584 shm_alloc(struct ucred *ucred, mode_t mode) 585 { 586 struct shmfd *shmfd; 587 588 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 589 shmfd->shm_size = 0; 590 shmfd->shm_uid = ucred->cr_uid; 591 shmfd->shm_gid = ucred->cr_gid; 592 shmfd->shm_mode = mode; 593 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 594 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 595 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 596 vfs_timestamp(&shmfd->shm_birthtime); 597 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 598 shmfd->shm_birthtime; 599 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 600 refcount_init(&shmfd->shm_refs, 1); 601 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 602 rangelock_init(&shmfd->shm_rl); 603 #ifdef MAC 604 mac_posixshm_init(shmfd); 605 mac_posixshm_create(ucred, shmfd); 606 #endif 607 608 return (shmfd); 609 } 610 611 struct shmfd * 612 shm_hold(struct shmfd *shmfd) 613 { 614 615 refcount_acquire(&shmfd->shm_refs); 616 return (shmfd); 617 } 618 619 void 620 shm_drop(struct shmfd *shmfd) 621 { 622 623 if (refcount_release(&shmfd->shm_refs)) { 624 #ifdef MAC 625 mac_posixshm_destroy(shmfd); 626 #endif 627 rangelock_destroy(&shmfd->shm_rl); 628 mtx_destroy(&shmfd->shm_mtx); 629 vm_object_deallocate(shmfd->shm_object); 630 free(shmfd, M_SHMFD); 631 } 632 } 633 634 /* 635 * Determine if the credentials have sufficient permissions for a 636 * specified combination of FREAD and FWRITE. 637 */ 638 int 639 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 640 { 641 accmode_t accmode; 642 int error; 643 644 accmode = 0; 645 if (flags & FREAD) 646 accmode |= VREAD; 647 if (flags & FWRITE) 648 accmode |= VWRITE; 649 mtx_lock(&shm_timestamp_lock); 650 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 651 accmode, ucred, NULL); 652 mtx_unlock(&shm_timestamp_lock); 653 return (error); 654 } 655 656 /* 657 * Dictionary management. We maintain an in-kernel dictionary to map 658 * paths to shmfd objects. We use the FNV hash on the path to store 659 * the mappings in a hash table. 660 */ 661 static void 662 shm_init(void *arg) 663 { 664 665 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 666 sx_init(&shm_dict_lock, "shm dictionary"); 667 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 668 new_unrhdr64(&shm_ino_unr, 1); 669 shm_dev_ino = devfs_alloc_cdp_inode(); 670 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 671 } 672 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 673 674 static struct shmfd * 675 shm_lookup(char *path, Fnv32_t fnv) 676 { 677 struct shm_mapping *map; 678 679 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 680 if (map->sm_fnv != fnv) 681 continue; 682 if (strcmp(map->sm_path, path) == 0) 683 return (map->sm_shmfd); 684 } 685 686 return (NULL); 687 } 688 689 static void 690 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 691 { 692 struct shm_mapping *map; 693 694 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 695 map->sm_path = path; 696 map->sm_fnv = fnv; 697 map->sm_shmfd = shm_hold(shmfd); 698 shmfd->shm_path = path; 699 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 700 } 701 702 static int 703 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 704 { 705 struct shm_mapping *map; 706 int error; 707 708 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 709 if (map->sm_fnv != fnv) 710 continue; 711 if (strcmp(map->sm_path, path) == 0) { 712 #ifdef MAC 713 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 714 if (error) 715 return (error); 716 #endif 717 error = shm_access(map->sm_shmfd, ucred, 718 FREAD | FWRITE); 719 if (error) 720 return (error); 721 map->sm_shmfd->shm_path = NULL; 722 LIST_REMOVE(map, sm_link); 723 shm_drop(map->sm_shmfd); 724 free(map->sm_path, M_SHMFD); 725 free(map, M_SHMFD); 726 return (0); 727 } 728 } 729 730 return (ENOENT); 731 } 732 733 int 734 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 735 int shmflags, struct filecaps *fcaps, const char *name __unused) 736 { 737 struct filedesc *fdp; 738 struct shmfd *shmfd; 739 struct file *fp; 740 char *path; 741 void *rl_cookie; 742 Fnv32_t fnv; 743 mode_t cmode; 744 int error, fd, initial_seals; 745 746 if ((shmflags & ~SHM_ALLOW_SEALING) != 0) 747 return (EINVAL); 748 749 initial_seals = F_SEAL_SEAL; 750 if ((shmflags & SHM_ALLOW_SEALING) != 0) 751 initial_seals &= ~F_SEAL_SEAL; 752 753 #ifdef CAPABILITY_MODE 754 /* 755 * shm_open(2) is only allowed for anonymous objects. 756 */ 757 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 758 return (ECAPMODE); 759 #endif 760 761 AUDIT_ARG_FFLAGS(flags); 762 AUDIT_ARG_MODE(mode); 763 764 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 765 return (EINVAL); 766 767 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 768 return (EINVAL); 769 770 /* 771 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 772 * If the decision is made later to allow additional seals, care must be 773 * taken below to ensure that the seals are properly set if the shmfd 774 * already existed -- this currently assumes that only F_SEAL_SEAL can 775 * be set and doesn't take further precautions to ensure the validity of 776 * the seals being added with respect to current mappings. 777 */ 778 if ((initial_seals & ~F_SEAL_SEAL) != 0) 779 return (EINVAL); 780 781 fdp = td->td_proc->p_fd; 782 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 783 784 /* 785 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 786 * by POSIX. We allow it to be unset here so that an in-kernel 787 * interface may be written as a thin layer around shm, optionally not 788 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 789 * in sys_shm_open() to keep this implementation compliant. 790 */ 791 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 792 if (error) 793 return (error); 794 795 /* A SHM_ANON path pointer creates an anonymous object. */ 796 if (userpath == SHM_ANON) { 797 /* A read-only anonymous object is pointless. */ 798 if ((flags & O_ACCMODE) == O_RDONLY) { 799 fdclose(td, fp, fd); 800 fdrop(fp, td); 801 return (EINVAL); 802 } 803 shmfd = shm_alloc(td->td_ucred, cmode); 804 shmfd->shm_seals = initial_seals; 805 } else { 806 error = shm_copyin_path(td, userpath, &path); 807 if (error != 0) { 808 fdclose(td, fp, fd); 809 fdrop(fp, td); 810 return (error); 811 } 812 813 AUDIT_ARG_UPATH1_CANON(path); 814 fnv = fnv_32_str(path, FNV1_32_INIT); 815 sx_xlock(&shm_dict_lock); 816 shmfd = shm_lookup(path, fnv); 817 if (shmfd == NULL) { 818 /* Object does not yet exist, create it if requested. */ 819 if (flags & O_CREAT) { 820 #ifdef MAC 821 error = mac_posixshm_check_create(td->td_ucred, 822 path); 823 if (error == 0) { 824 #endif 825 shmfd = shm_alloc(td->td_ucred, cmode); 826 shmfd->shm_seals = initial_seals; 827 shm_insert(path, fnv, shmfd); 828 #ifdef MAC 829 } 830 #endif 831 } else { 832 free(path, M_SHMFD); 833 error = ENOENT; 834 } 835 } else { 836 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 837 &shmfd->shm_mtx); 838 839 /* 840 * kern_shm_open() likely shouldn't ever error out on 841 * trying to set a seal that already exists, unlike 842 * F_ADD_SEALS. This would break terribly as 843 * shm_open(2) actually sets F_SEAL_SEAL to maintain 844 * historical behavior where the underlying file could 845 * not be sealed. 846 */ 847 initial_seals &= ~shmfd->shm_seals; 848 849 /* 850 * Object already exists, obtain a new 851 * reference if requested and permitted. 852 */ 853 free(path, M_SHMFD); 854 855 /* 856 * initial_seals can't set additional seals if we've 857 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 858 * then we've already removed that one from 859 * initial_seals. This is currently redundant as we 860 * only allow setting F_SEAL_SEAL at creation time, but 861 * it's cheap to check and decreases the effort required 862 * to allow additional seals. 863 */ 864 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 865 initial_seals != 0) 866 error = EPERM; 867 else if ((flags & (O_CREAT | O_EXCL)) == 868 (O_CREAT | O_EXCL)) 869 error = EEXIST; 870 else { 871 #ifdef MAC 872 error = mac_posixshm_check_open(td->td_ucred, 873 shmfd, FFLAGS(flags & O_ACCMODE)); 874 if (error == 0) 875 #endif 876 error = shm_access(shmfd, td->td_ucred, 877 FFLAGS(flags & O_ACCMODE)); 878 } 879 880 /* 881 * Truncate the file back to zero length if 882 * O_TRUNC was specified and the object was 883 * opened with read/write. 884 */ 885 if (error == 0 && 886 (flags & (O_ACCMODE | O_TRUNC)) == 887 (O_RDWR | O_TRUNC)) { 888 VM_OBJECT_WLOCK(shmfd->shm_object); 889 #ifdef MAC 890 error = mac_posixshm_check_truncate( 891 td->td_ucred, fp->f_cred, shmfd); 892 if (error == 0) 893 #endif 894 error = shm_dotruncate_locked(shmfd, 0, 895 rl_cookie); 896 VM_OBJECT_WUNLOCK(shmfd->shm_object); 897 } 898 if (error == 0) { 899 /* 900 * Currently we only allow F_SEAL_SEAL to be 901 * set initially. As noted above, this would 902 * need to be reworked should that change. 903 */ 904 shmfd->shm_seals |= initial_seals; 905 shm_hold(shmfd); 906 } 907 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 908 &shmfd->shm_mtx); 909 } 910 sx_xunlock(&shm_dict_lock); 911 912 if (error) { 913 fdclose(td, fp, fd); 914 fdrop(fp, td); 915 return (error); 916 } 917 } 918 919 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 920 921 td->td_retval[0] = fd; 922 fdrop(fp, td); 923 924 return (0); 925 } 926 927 /* System calls. */ 928 #ifdef COMPAT_FREEBSD12 929 int 930 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 931 { 932 933 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 934 uap->mode, NULL)); 935 } 936 #endif 937 938 int 939 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 940 { 941 char *path; 942 Fnv32_t fnv; 943 int error; 944 945 error = shm_copyin_path(td, uap->path, &path); 946 if (error != 0) 947 return (error); 948 949 AUDIT_ARG_UPATH1_CANON(path); 950 fnv = fnv_32_str(path, FNV1_32_INIT); 951 sx_xlock(&shm_dict_lock); 952 error = shm_remove(path, fnv, td->td_ucred); 953 sx_xunlock(&shm_dict_lock); 954 free(path, M_TEMP); 955 956 return (error); 957 } 958 959 int 960 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 961 { 962 char *path_from = NULL, *path_to = NULL; 963 Fnv32_t fnv_from, fnv_to; 964 struct shmfd *fd_from; 965 struct shmfd *fd_to; 966 int error; 967 int flags; 968 969 flags = uap->flags; 970 AUDIT_ARG_FFLAGS(flags); 971 972 /* 973 * Make sure the user passed only valid flags. 974 * If you add a new flag, please add a new term here. 975 */ 976 if ((flags & ~( 977 SHM_RENAME_NOREPLACE | 978 SHM_RENAME_EXCHANGE 979 )) != 0) { 980 error = EINVAL; 981 goto out; 982 } 983 984 /* 985 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 986 * force the user to choose one or the other. 987 */ 988 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 989 (flags & SHM_RENAME_EXCHANGE) != 0) { 990 error = EINVAL; 991 goto out; 992 } 993 994 /* Renaming to or from anonymous makes no sense */ 995 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 996 error = EINVAL; 997 goto out; 998 } 999 1000 error = shm_copyin_path(td, uap->path_from, &path_from); 1001 if (error != 0) 1002 goto out; 1003 1004 error = shm_copyin_path(td, uap->path_to, &path_to); 1005 if (error != 0) 1006 goto out; 1007 1008 AUDIT_ARG_UPATH1_CANON(path_from); 1009 AUDIT_ARG_UPATH2_CANON(path_to); 1010 1011 /* Rename with from/to equal is a no-op */ 1012 if (strcmp(path_from, path_to) == 0) 1013 goto out; 1014 1015 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1016 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1017 1018 sx_xlock(&shm_dict_lock); 1019 1020 fd_from = shm_lookup(path_from, fnv_from); 1021 if (fd_from == NULL) { 1022 error = ENOENT; 1023 goto out_locked; 1024 } 1025 1026 fd_to = shm_lookup(path_to, fnv_to); 1027 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1028 error = EEXIST; 1029 goto out_locked; 1030 } 1031 1032 /* 1033 * Unconditionally prevents shm_remove from invalidating the 'from' 1034 * shm's state. 1035 */ 1036 shm_hold(fd_from); 1037 error = shm_remove(path_from, fnv_from, td->td_ucred); 1038 1039 /* 1040 * One of my assumptions failed if ENOENT (e.g. locking didn't 1041 * protect us) 1042 */ 1043 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1044 path_from)); 1045 if (error != 0) { 1046 shm_drop(fd_from); 1047 goto out_locked; 1048 } 1049 1050 /* 1051 * If we are exchanging, we need to ensure the shm_remove below 1052 * doesn't invalidate the dest shm's state. 1053 */ 1054 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1055 shm_hold(fd_to); 1056 1057 /* 1058 * NOTE: if path_to is not already in the hash, c'est la vie; 1059 * it simply means we have nothing already at path_to to unlink. 1060 * That is the ENOENT case. 1061 * 1062 * If we somehow don't have access to unlink this guy, but 1063 * did for the shm at path_from, then relink the shm to path_from 1064 * and abort with EACCES. 1065 * 1066 * All other errors: that is weird; let's relink and abort the 1067 * operation. 1068 */ 1069 error = shm_remove(path_to, fnv_to, td->td_ucred); 1070 if (error != 0 && error != ENOENT) { 1071 shm_insert(path_from, fnv_from, fd_from); 1072 shm_drop(fd_from); 1073 /* Don't free path_from now, since the hash references it */ 1074 path_from = NULL; 1075 goto out_locked; 1076 } 1077 1078 error = 0; 1079 1080 shm_insert(path_to, fnv_to, fd_from); 1081 1082 /* Don't free path_to now, since the hash references it */ 1083 path_to = NULL; 1084 1085 /* We kept a ref when we removed, and incremented again in insert */ 1086 shm_drop(fd_from); 1087 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1088 fd_from->shm_refs)); 1089 1090 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1091 shm_insert(path_from, fnv_from, fd_to); 1092 path_from = NULL; 1093 shm_drop(fd_to); 1094 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1095 fd_to->shm_refs)); 1096 } 1097 1098 out_locked: 1099 sx_xunlock(&shm_dict_lock); 1100 1101 out: 1102 free(path_from, M_SHMFD); 1103 free(path_to, M_SHMFD); 1104 return (error); 1105 } 1106 1107 int 1108 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1109 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1110 vm_ooffset_t foff, struct thread *td) 1111 { 1112 struct shmfd *shmfd; 1113 vm_prot_t maxprot; 1114 int error; 1115 bool writecnt; 1116 void *rl_cookie; 1117 1118 shmfd = fp->f_data; 1119 maxprot = VM_PROT_NONE; 1120 1121 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1122 &shmfd->shm_mtx); 1123 /* FREAD should always be set. */ 1124 if ((fp->f_flag & FREAD) != 0) 1125 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1126 1127 /* 1128 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1129 * mapping with a write seal applied. 1130 */ 1131 if ((fp->f_flag & FWRITE) != 0 && ((flags & MAP_SHARED) == 0 || 1132 (shmfd->shm_seals & F_SEAL_WRITE) == 0)) 1133 maxprot |= VM_PROT_WRITE; 1134 1135 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; 1136 1137 if (writecnt && (shmfd->shm_seals & F_SEAL_WRITE) != 0) { 1138 error = EPERM; 1139 goto out; 1140 } 1141 1142 /* Don't permit shared writable mappings on read-only descriptors. */ 1143 if (writecnt && (maxprot & VM_PROT_WRITE) == 0) { 1144 error = EACCES; 1145 goto out; 1146 } 1147 maxprot &= cap_maxprot; 1148 1149 /* See comment in vn_mmap(). */ 1150 if ( 1151 #ifdef _LP64 1152 objsize > OFF_MAX || 1153 #endif 1154 foff < 0 || foff > OFF_MAX - objsize) { 1155 error = EINVAL; 1156 goto out; 1157 } 1158 1159 #ifdef MAC 1160 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1161 if (error != 0) 1162 goto out; 1163 #endif 1164 1165 mtx_lock(&shm_timestamp_lock); 1166 vfs_timestamp(&shmfd->shm_atime); 1167 mtx_unlock(&shm_timestamp_lock); 1168 vm_object_reference(shmfd->shm_object); 1169 1170 if (writecnt) 1171 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 1172 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1173 shmfd->shm_object, foff, writecnt, td); 1174 if (error != 0) { 1175 if (writecnt) 1176 vm_pager_release_writecount(shmfd->shm_object, 0, 1177 objsize); 1178 vm_object_deallocate(shmfd->shm_object); 1179 } 1180 out: 1181 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1182 return (error); 1183 } 1184 1185 static int 1186 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1187 struct thread *td) 1188 { 1189 struct shmfd *shmfd; 1190 int error; 1191 1192 error = 0; 1193 shmfd = fp->f_data; 1194 mtx_lock(&shm_timestamp_lock); 1195 /* 1196 * SUSv4 says that x bits of permission need not be affected. 1197 * Be consistent with our shm_open there. 1198 */ 1199 #ifdef MAC 1200 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1201 if (error != 0) 1202 goto out; 1203 #endif 1204 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 1205 shmfd->shm_gid, VADMIN, active_cred, NULL); 1206 if (error != 0) 1207 goto out; 1208 shmfd->shm_mode = mode & ACCESSPERMS; 1209 out: 1210 mtx_unlock(&shm_timestamp_lock); 1211 return (error); 1212 } 1213 1214 static int 1215 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1216 struct thread *td) 1217 { 1218 struct shmfd *shmfd; 1219 int error; 1220 1221 error = 0; 1222 shmfd = fp->f_data; 1223 mtx_lock(&shm_timestamp_lock); 1224 #ifdef MAC 1225 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1226 if (error != 0) 1227 goto out; 1228 #endif 1229 if (uid == (uid_t)-1) 1230 uid = shmfd->shm_uid; 1231 if (gid == (gid_t)-1) 1232 gid = shmfd->shm_gid; 1233 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1234 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1235 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1236 goto out; 1237 shmfd->shm_uid = uid; 1238 shmfd->shm_gid = gid; 1239 out: 1240 mtx_unlock(&shm_timestamp_lock); 1241 return (error); 1242 } 1243 1244 /* 1245 * Helper routines to allow the backing object of a shared memory file 1246 * descriptor to be mapped in the kernel. 1247 */ 1248 int 1249 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1250 { 1251 struct shmfd *shmfd; 1252 vm_offset_t kva, ofs; 1253 vm_object_t obj; 1254 int rv; 1255 1256 if (fp->f_type != DTYPE_SHM) 1257 return (EINVAL); 1258 shmfd = fp->f_data; 1259 obj = shmfd->shm_object; 1260 VM_OBJECT_WLOCK(obj); 1261 /* 1262 * XXXRW: This validation is probably insufficient, and subject to 1263 * sign errors. It should be fixed. 1264 */ 1265 if (offset >= shmfd->shm_size || 1266 offset + size > round_page(shmfd->shm_size)) { 1267 VM_OBJECT_WUNLOCK(obj); 1268 return (EINVAL); 1269 } 1270 1271 shmfd->shm_kmappings++; 1272 vm_object_reference_locked(obj); 1273 VM_OBJECT_WUNLOCK(obj); 1274 1275 /* Map the object into the kernel_map and wire it. */ 1276 kva = vm_map_min(kernel_map); 1277 ofs = offset & PAGE_MASK; 1278 offset = trunc_page(offset); 1279 size = round_page(size + ofs); 1280 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1281 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1282 VM_PROT_READ | VM_PROT_WRITE, 0); 1283 if (rv == KERN_SUCCESS) { 1284 rv = vm_map_wire(kernel_map, kva, kva + size, 1285 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1286 if (rv == KERN_SUCCESS) { 1287 *memp = (void *)(kva + ofs); 1288 return (0); 1289 } 1290 vm_map_remove(kernel_map, kva, kva + size); 1291 } else 1292 vm_object_deallocate(obj); 1293 1294 /* On failure, drop our mapping reference. */ 1295 VM_OBJECT_WLOCK(obj); 1296 shmfd->shm_kmappings--; 1297 VM_OBJECT_WUNLOCK(obj); 1298 1299 return (vm_mmap_to_errno(rv)); 1300 } 1301 1302 /* 1303 * We require the caller to unmap the entire entry. This allows us to 1304 * safely decrement shm_kmappings when a mapping is removed. 1305 */ 1306 int 1307 shm_unmap(struct file *fp, void *mem, size_t size) 1308 { 1309 struct shmfd *shmfd; 1310 vm_map_entry_t entry; 1311 vm_offset_t kva, ofs; 1312 vm_object_t obj; 1313 vm_pindex_t pindex; 1314 vm_prot_t prot; 1315 boolean_t wired; 1316 vm_map_t map; 1317 int rv; 1318 1319 if (fp->f_type != DTYPE_SHM) 1320 return (EINVAL); 1321 shmfd = fp->f_data; 1322 kva = (vm_offset_t)mem; 1323 ofs = kva & PAGE_MASK; 1324 kva = trunc_page(kva); 1325 size = round_page(size + ofs); 1326 map = kernel_map; 1327 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1328 &obj, &pindex, &prot, &wired); 1329 if (rv != KERN_SUCCESS) 1330 return (EINVAL); 1331 if (entry->start != kva || entry->end != kva + size) { 1332 vm_map_lookup_done(map, entry); 1333 return (EINVAL); 1334 } 1335 vm_map_lookup_done(map, entry); 1336 if (obj != shmfd->shm_object) 1337 return (EINVAL); 1338 vm_map_remove(map, kva, kva + size); 1339 VM_OBJECT_WLOCK(obj); 1340 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1341 shmfd->shm_kmappings--; 1342 VM_OBJECT_WUNLOCK(obj); 1343 return (0); 1344 } 1345 1346 static int 1347 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1348 { 1349 const char *path, *pr_path; 1350 size_t pr_pathlen; 1351 bool visible; 1352 1353 sx_assert(&shm_dict_lock, SA_LOCKED); 1354 kif->kf_type = KF_TYPE_SHM; 1355 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1356 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1357 if (shmfd->shm_path != NULL) { 1358 if (shmfd->shm_path != NULL) { 1359 path = shmfd->shm_path; 1360 pr_path = curthread->td_ucred->cr_prison->pr_path; 1361 if (strcmp(pr_path, "/") != 0) { 1362 /* Return the jail-rooted pathname. */ 1363 pr_pathlen = strlen(pr_path); 1364 visible = strncmp(path, pr_path, pr_pathlen) 1365 == 0 && path[pr_pathlen] == '/'; 1366 if (list && !visible) 1367 return (EPERM); 1368 if (visible) 1369 path += pr_pathlen; 1370 } 1371 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1372 } 1373 } 1374 return (0); 1375 } 1376 1377 static int 1378 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1379 struct filedesc *fdp __unused) 1380 { 1381 int res; 1382 1383 sx_slock(&shm_dict_lock); 1384 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1385 sx_sunlock(&shm_dict_lock); 1386 return (res); 1387 } 1388 1389 static int 1390 shm_add_seals(struct file *fp, int seals) 1391 { 1392 struct shmfd *shmfd; 1393 void *rl_cookie; 1394 vm_ooffset_t writemappings; 1395 int error, nseals; 1396 1397 error = 0; 1398 shmfd = fp->f_data; 1399 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1400 &shmfd->shm_mtx); 1401 1402 /* Even already-set seals should result in EPERM. */ 1403 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1404 error = EPERM; 1405 goto out; 1406 } 1407 nseals = seals & ~shmfd->shm_seals; 1408 if ((nseals & F_SEAL_WRITE) != 0) { 1409 /* 1410 * The rangelock above prevents writable mappings from being 1411 * added after we've started applying seals. The RLOCK here 1412 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1413 * writemappings will be done without a rangelock. 1414 */ 1415 VM_OBJECT_RLOCK(shmfd->shm_object); 1416 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1417 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1418 /* kmappings are also writable */ 1419 if (writemappings > 0) { 1420 error = EBUSY; 1421 goto out; 1422 } 1423 } 1424 shmfd->shm_seals |= nseals; 1425 out: 1426 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1427 return (error); 1428 } 1429 1430 static int 1431 shm_get_seals(struct file *fp, int *seals) 1432 { 1433 struct shmfd *shmfd; 1434 1435 shmfd = fp->f_data; 1436 *seals = shmfd->shm_seals; 1437 return (0); 1438 } 1439 1440 static int 1441 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1442 { 1443 struct shm_mapping *shmm; 1444 struct sbuf sb; 1445 struct kinfo_file kif; 1446 u_long i; 1447 ssize_t curlen; 1448 int error, error2; 1449 1450 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1451 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1452 curlen = 0; 1453 error = 0; 1454 sx_slock(&shm_dict_lock); 1455 for (i = 0; i < shm_hash + 1; i++) { 1456 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1457 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1458 &kif, true); 1459 if (error == EPERM) 1460 continue; 1461 if (error != 0) 1462 break; 1463 pack_kinfo(&kif); 1464 if (req->oldptr != NULL && 1465 kif.kf_structsize + curlen > req->oldlen) 1466 break; 1467 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1468 0 : ENOMEM; 1469 if (error != 0) 1470 break; 1471 curlen += kif.kf_structsize; 1472 } 1473 } 1474 sx_sunlock(&shm_dict_lock); 1475 error2 = sbuf_finish(&sb); 1476 sbuf_delete(&sb); 1477 return (error != 0 ? error : error2); 1478 } 1479 1480 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1481 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1482 NULL, 0, sysctl_posix_shm_list, "", 1483 "POSIX SHM list"); 1484 1485 int 1486 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1487 struct filecaps *caps) 1488 { 1489 1490 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1491 } 1492 1493 /* 1494 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1495 * caller, and libc will enforce it for the traditional shm_open() call. This 1496 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1497 * interface also includes a 'name' argument that is currently unused, but could 1498 * potentially be exported later via some interface for debugging purposes. 1499 * From the kernel's perspective, it is optional. Individual consumers like 1500 * memfd_create() may require it in order to be compatible with other systems 1501 * implementing the same function. 1502 */ 1503 int 1504 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1505 { 1506 1507 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1508 uap->shmflags, NULL, uap->name)); 1509 } 1510