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 static fo_fallocate_t shm_fallocate; 142 143 /* File descriptor operations. */ 144 struct fileops shm_ops = { 145 .fo_read = shm_read, 146 .fo_write = shm_write, 147 .fo_truncate = shm_truncate, 148 .fo_ioctl = shm_ioctl, 149 .fo_poll = invfo_poll, 150 .fo_kqfilter = invfo_kqfilter, 151 .fo_stat = shm_stat, 152 .fo_close = shm_close, 153 .fo_chmod = shm_chmod, 154 .fo_chown = shm_chown, 155 .fo_sendfile = vn_sendfile, 156 .fo_seek = shm_seek, 157 .fo_fill_kinfo = shm_fill_kinfo, 158 .fo_mmap = shm_mmap, 159 .fo_get_seals = shm_get_seals, 160 .fo_add_seals = shm_add_seals, 161 .fo_fallocate = shm_fallocate, 162 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 163 }; 164 165 FEATURE(posix_shm, "POSIX shared memory"); 166 167 static int 168 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 169 { 170 vm_page_t m; 171 vm_pindex_t idx; 172 size_t tlen; 173 int error, offset, rv; 174 175 idx = OFF_TO_IDX(uio->uio_offset); 176 offset = uio->uio_offset & PAGE_MASK; 177 tlen = MIN(PAGE_SIZE - offset, len); 178 179 VM_OBJECT_WLOCK(obj); 180 181 /* 182 * Read I/O without either a corresponding resident page or swap 183 * page: use zero_region. This is intended to avoid instantiating 184 * pages on read from a sparse region. 185 */ 186 if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL && 187 !vm_pager_has_page(obj, idx, NULL, NULL)) { 188 VM_OBJECT_WUNLOCK(obj); 189 return (uiomove(__DECONST(void *, zero_region), tlen, uio)); 190 } 191 192 /* 193 * Parallel reads of the page content from disk are prevented 194 * by exclusive busy. 195 * 196 * Although the tmpfs vnode lock is held here, it is 197 * nonetheless safe to sleep waiting for a free page. The 198 * pageout daemon does not need to acquire the tmpfs vnode 199 * lock to page out tobj's pages because tobj is a OBJT_SWAP 200 * type object. 201 */ 202 rv = vm_page_grab_valid(&m, obj, idx, 203 VM_ALLOC_NORMAL | VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY); 204 if (rv != VM_PAGER_OK) { 205 VM_OBJECT_WUNLOCK(obj); 206 printf("uiomove_object: vm_obj %p idx %jd pager error %d\n", 207 obj, idx, rv); 208 return (EIO); 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_page_set_dirty(m); 214 vm_page_activate(m); 215 vm_page_sunbusy(m); 216 217 return (error); 218 } 219 220 int 221 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 222 { 223 ssize_t resid; 224 size_t len; 225 int error; 226 227 error = 0; 228 while ((resid = uio->uio_resid) > 0) { 229 if (obj_size <= uio->uio_offset) 230 break; 231 len = MIN(obj_size - uio->uio_offset, resid); 232 if (len == 0) 233 break; 234 error = uiomove_object_page(obj, len, uio); 235 if (error != 0 || resid == uio->uio_resid) 236 break; 237 } 238 return (error); 239 } 240 241 static int 242 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 243 { 244 struct shmfd *shmfd; 245 off_t foffset; 246 int error; 247 248 shmfd = fp->f_data; 249 foffset = foffset_lock(fp, 0); 250 error = 0; 251 switch (whence) { 252 case L_INCR: 253 if (foffset < 0 || 254 (offset > 0 && foffset > OFF_MAX - offset)) { 255 error = EOVERFLOW; 256 break; 257 } 258 offset += foffset; 259 break; 260 case L_XTND: 261 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 262 error = EOVERFLOW; 263 break; 264 } 265 offset += shmfd->shm_size; 266 break; 267 case L_SET: 268 break; 269 default: 270 error = EINVAL; 271 } 272 if (error == 0) { 273 if (offset < 0 || offset > shmfd->shm_size) 274 error = EINVAL; 275 else 276 td->td_uretoff.tdu_off = offset; 277 } 278 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 279 return (error); 280 } 281 282 static int 283 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 284 int flags, struct thread *td) 285 { 286 struct shmfd *shmfd; 287 void *rl_cookie; 288 int error; 289 290 shmfd = fp->f_data; 291 #ifdef MAC 292 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 293 if (error) 294 return (error); 295 #endif 296 foffset_lock_uio(fp, uio, flags); 297 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 298 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 299 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 300 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 301 foffset_unlock_uio(fp, uio, flags); 302 return (error); 303 } 304 305 static int 306 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 307 int flags, struct thread *td) 308 { 309 struct shmfd *shmfd; 310 void *rl_cookie; 311 int error; 312 313 shmfd = fp->f_data; 314 #ifdef MAC 315 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 316 if (error) 317 return (error); 318 #endif 319 foffset_lock_uio(fp, uio, flags); 320 if ((flags & FOF_OFFSET) == 0) { 321 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 322 &shmfd->shm_mtx); 323 } else { 324 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 325 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 326 } 327 if ((shmfd->shm_seals & F_SEAL_WRITE) != 0) 328 error = EPERM; 329 else 330 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 331 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 332 foffset_unlock_uio(fp, uio, flags); 333 return (error); 334 } 335 336 static int 337 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 338 struct thread *td) 339 { 340 struct shmfd *shmfd; 341 #ifdef MAC 342 int error; 343 #endif 344 345 shmfd = fp->f_data; 346 #ifdef MAC 347 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 348 if (error) 349 return (error); 350 #endif 351 return (shm_dotruncate(shmfd, length)); 352 } 353 354 int 355 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred, 356 struct thread *td) 357 { 358 359 switch (com) { 360 case FIONBIO: 361 case FIOASYNC: 362 /* 363 * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work, 364 * just like it would on an unlinked regular file 365 */ 366 return (0); 367 default: 368 return (ENOTTY); 369 } 370 } 371 372 static int 373 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 374 struct thread *td) 375 { 376 struct shmfd *shmfd; 377 #ifdef MAC 378 int error; 379 #endif 380 381 shmfd = fp->f_data; 382 383 #ifdef MAC 384 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 385 if (error) 386 return (error); 387 #endif 388 389 /* 390 * Attempt to return sanish values for fstat() on a memory file 391 * descriptor. 392 */ 393 bzero(sb, sizeof(*sb)); 394 sb->st_blksize = PAGE_SIZE; 395 sb->st_size = shmfd->shm_size; 396 sb->st_blocks = howmany(sb->st_size, sb->st_blksize); 397 mtx_lock(&shm_timestamp_lock); 398 sb->st_atim = shmfd->shm_atime; 399 sb->st_ctim = shmfd->shm_ctime; 400 sb->st_mtim = shmfd->shm_mtime; 401 sb->st_birthtim = shmfd->shm_birthtime; 402 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 403 sb->st_uid = shmfd->shm_uid; 404 sb->st_gid = shmfd->shm_gid; 405 mtx_unlock(&shm_timestamp_lock); 406 sb->st_dev = shm_dev_ino; 407 sb->st_ino = shmfd->shm_ino; 408 sb->st_nlink = shmfd->shm_object->ref_count; 409 410 return (0); 411 } 412 413 static int 414 shm_close(struct file *fp, struct thread *td) 415 { 416 struct shmfd *shmfd; 417 418 shmfd = fp->f_data; 419 fp->f_data = NULL; 420 shm_drop(shmfd); 421 422 return (0); 423 } 424 425 static int 426 shm_copyin_path(struct thread *td, const char *userpath_in, char **path_out) { 427 int error; 428 char *path; 429 const char *pr_path; 430 size_t pr_pathlen; 431 432 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 433 pr_path = td->td_ucred->cr_prison->pr_path; 434 435 /* Construct a full pathname for jailed callers. */ 436 pr_pathlen = strcmp(pr_path, "/") == 437 0 ? 0 : strlcpy(path, pr_path, MAXPATHLEN); 438 error = copyinstr(userpath_in, path + pr_pathlen, 439 MAXPATHLEN - pr_pathlen, NULL); 440 if (error != 0) 441 goto out; 442 443 #ifdef KTRACE 444 if (KTRPOINT(curthread, KTR_NAMEI)) 445 ktrnamei(path); 446 #endif 447 448 /* Require paths to start with a '/' character. */ 449 if (path[pr_pathlen] != '/') { 450 error = EINVAL; 451 goto out; 452 } 453 454 *path_out = path; 455 456 out: 457 if (error != 0) 458 free(path, M_SHMFD); 459 460 return (error); 461 } 462 463 static int 464 shm_dotruncate_locked(struct shmfd *shmfd, off_t length, void *rl_cookie) 465 { 466 vm_object_t object; 467 vm_page_t m; 468 vm_pindex_t idx, nobjsize; 469 vm_ooffset_t delta; 470 int base, rv; 471 472 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 473 object = shmfd->shm_object; 474 VM_OBJECT_ASSERT_WLOCKED(object); 475 rangelock_cookie_assert(rl_cookie, RA_WLOCKED); 476 if (length == shmfd->shm_size) 477 return (0); 478 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 479 480 /* Are we shrinking? If so, trim the end. */ 481 if (length < shmfd->shm_size) { 482 if ((shmfd->shm_seals & F_SEAL_SHRINK) != 0) 483 return (EPERM); 484 485 /* 486 * Disallow any requests to shrink the size if this 487 * object is mapped into the kernel. 488 */ 489 if (shmfd->shm_kmappings > 0) 490 return (EBUSY); 491 492 /* 493 * Zero the truncated part of the last page. 494 */ 495 base = length & PAGE_MASK; 496 if (base != 0) { 497 idx = OFF_TO_IDX(length); 498 retry: 499 m = vm_page_grab(object, idx, VM_ALLOC_NOCREAT); 500 if (m != NULL) { 501 MPASS(vm_page_all_valid(m)); 502 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 503 m = vm_page_alloc(object, idx, 504 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL); 505 if (m == NULL) 506 goto retry; 507 rv = vm_pager_get_pages(object, &m, 1, NULL, 508 NULL); 509 if (rv == VM_PAGER_OK) { 510 /* 511 * Since the page was not resident, 512 * and therefore not recently 513 * accessed, immediately enqueue it 514 * for asynchronous laundering. The 515 * current operation is not regarded 516 * as an access. 517 */ 518 vm_page_launder(m); 519 } else { 520 vm_page_free(m); 521 VM_OBJECT_WUNLOCK(object); 522 return (EIO); 523 } 524 } 525 if (m != NULL) { 526 pmap_zero_page_area(m, base, PAGE_SIZE - base); 527 KASSERT(vm_page_all_valid(m), 528 ("shm_dotruncate: page %p is invalid", m)); 529 vm_page_set_dirty(m); 530 vm_page_xunbusy(m); 531 } 532 } 533 delta = IDX_TO_OFF(object->size - nobjsize); 534 535 /* Toss in memory pages. */ 536 if (nobjsize < object->size) 537 vm_object_page_remove(object, nobjsize, object->size, 538 0); 539 540 /* Toss pages from swap. */ 541 if (object->type == OBJT_SWAP) 542 swap_pager_freespace(object, nobjsize, delta); 543 544 /* Free the swap accounted for shm */ 545 swap_release_by_cred(delta, object->cred); 546 object->charge -= delta; 547 } else { 548 if ((shmfd->shm_seals & F_SEAL_GROW) != 0) 549 return (EPERM); 550 551 /* Try to reserve additional swap space. */ 552 delta = IDX_TO_OFF(nobjsize - object->size); 553 if (!swap_reserve_by_cred(delta, object->cred)) 554 return (ENOMEM); 555 object->charge += delta; 556 } 557 shmfd->shm_size = length; 558 mtx_lock(&shm_timestamp_lock); 559 vfs_timestamp(&shmfd->shm_ctime); 560 shmfd->shm_mtime = shmfd->shm_ctime; 561 mtx_unlock(&shm_timestamp_lock); 562 object->size = nobjsize; 563 return (0); 564 } 565 566 int 567 shm_dotruncate(struct shmfd *shmfd, off_t length) 568 { 569 void *rl_cookie; 570 int error; 571 572 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 573 &shmfd->shm_mtx); 574 VM_OBJECT_WLOCK(shmfd->shm_object); 575 error = shm_dotruncate_locked(shmfd, length, rl_cookie); 576 VM_OBJECT_WUNLOCK(shmfd->shm_object); 577 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 578 return (error); 579 } 580 581 /* 582 * shmfd object management including creation and reference counting 583 * routines. 584 */ 585 struct shmfd * 586 shm_alloc(struct ucred *ucred, mode_t mode) 587 { 588 struct shmfd *shmfd; 589 590 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 591 shmfd->shm_size = 0; 592 shmfd->shm_uid = ucred->cr_uid; 593 shmfd->shm_gid = ucred->cr_gid; 594 shmfd->shm_mode = mode; 595 shmfd->shm_object = vm_pager_allocate(OBJT_SWAP, NULL, 596 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 597 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 598 vfs_timestamp(&shmfd->shm_birthtime); 599 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 600 shmfd->shm_birthtime; 601 shmfd->shm_ino = alloc_unr64(&shm_ino_unr); 602 refcount_init(&shmfd->shm_refs, 1); 603 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 604 rangelock_init(&shmfd->shm_rl); 605 #ifdef MAC 606 mac_posixshm_init(shmfd); 607 mac_posixshm_create(ucred, shmfd); 608 #endif 609 610 return (shmfd); 611 } 612 613 struct shmfd * 614 shm_hold(struct shmfd *shmfd) 615 { 616 617 refcount_acquire(&shmfd->shm_refs); 618 return (shmfd); 619 } 620 621 void 622 shm_drop(struct shmfd *shmfd) 623 { 624 625 if (refcount_release(&shmfd->shm_refs)) { 626 #ifdef MAC 627 mac_posixshm_destroy(shmfd); 628 #endif 629 rangelock_destroy(&shmfd->shm_rl); 630 mtx_destroy(&shmfd->shm_mtx); 631 vm_object_deallocate(shmfd->shm_object); 632 free(shmfd, M_SHMFD); 633 } 634 } 635 636 /* 637 * Determine if the credentials have sufficient permissions for a 638 * specified combination of FREAD and FWRITE. 639 */ 640 int 641 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 642 { 643 accmode_t accmode; 644 int error; 645 646 accmode = 0; 647 if (flags & FREAD) 648 accmode |= VREAD; 649 if (flags & FWRITE) 650 accmode |= VWRITE; 651 mtx_lock(&shm_timestamp_lock); 652 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 653 accmode, ucred, NULL); 654 mtx_unlock(&shm_timestamp_lock); 655 return (error); 656 } 657 658 /* 659 * Dictionary management. We maintain an in-kernel dictionary to map 660 * paths to shmfd objects. We use the FNV hash on the path to store 661 * the mappings in a hash table. 662 */ 663 static void 664 shm_init(void *arg) 665 { 666 667 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 668 sx_init(&shm_dict_lock, "shm dictionary"); 669 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 670 new_unrhdr64(&shm_ino_unr, 1); 671 shm_dev_ino = devfs_alloc_cdp_inode(); 672 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 673 } 674 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 675 676 static struct shmfd * 677 shm_lookup(char *path, Fnv32_t fnv) 678 { 679 struct shm_mapping *map; 680 681 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 682 if (map->sm_fnv != fnv) 683 continue; 684 if (strcmp(map->sm_path, path) == 0) 685 return (map->sm_shmfd); 686 } 687 688 return (NULL); 689 } 690 691 static void 692 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 693 { 694 struct shm_mapping *map; 695 696 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 697 map->sm_path = path; 698 map->sm_fnv = fnv; 699 map->sm_shmfd = shm_hold(shmfd); 700 shmfd->shm_path = path; 701 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 702 } 703 704 static int 705 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 706 { 707 struct shm_mapping *map; 708 int error; 709 710 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 711 if (map->sm_fnv != fnv) 712 continue; 713 if (strcmp(map->sm_path, path) == 0) { 714 #ifdef MAC 715 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 716 if (error) 717 return (error); 718 #endif 719 error = shm_access(map->sm_shmfd, ucred, 720 FREAD | FWRITE); 721 if (error) 722 return (error); 723 map->sm_shmfd->shm_path = NULL; 724 LIST_REMOVE(map, sm_link); 725 shm_drop(map->sm_shmfd); 726 free(map->sm_path, M_SHMFD); 727 free(map, M_SHMFD); 728 return (0); 729 } 730 } 731 732 return (ENOENT); 733 } 734 735 int 736 kern_shm_open2(struct thread *td, const char *userpath, int flags, mode_t mode, 737 int shmflags, struct filecaps *fcaps, const char *name __unused) 738 { 739 struct filedesc *fdp; 740 struct shmfd *shmfd; 741 struct file *fp; 742 char *path; 743 void *rl_cookie; 744 Fnv32_t fnv; 745 mode_t cmode; 746 int error, fd, initial_seals; 747 748 if ((shmflags & ~SHM_ALLOW_SEALING) != 0) 749 return (EINVAL); 750 751 initial_seals = F_SEAL_SEAL; 752 if ((shmflags & SHM_ALLOW_SEALING) != 0) 753 initial_seals &= ~F_SEAL_SEAL; 754 755 #ifdef CAPABILITY_MODE 756 /* 757 * shm_open(2) is only allowed for anonymous objects. 758 */ 759 if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON)) 760 return (ECAPMODE); 761 #endif 762 763 AUDIT_ARG_FFLAGS(flags); 764 AUDIT_ARG_MODE(mode); 765 766 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) 767 return (EINVAL); 768 769 if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 770 return (EINVAL); 771 772 /* 773 * Currently only F_SEAL_SEAL may be set when creating or opening shmfd. 774 * If the decision is made later to allow additional seals, care must be 775 * taken below to ensure that the seals are properly set if the shmfd 776 * already existed -- this currently assumes that only F_SEAL_SEAL can 777 * be set and doesn't take further precautions to ensure the validity of 778 * the seals being added with respect to current mappings. 779 */ 780 if ((initial_seals & ~F_SEAL_SEAL) != 0) 781 return (EINVAL); 782 783 fdp = td->td_proc->p_fd; 784 cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 785 786 /* 787 * shm_open(2) created shm should always have O_CLOEXEC set, as mandated 788 * by POSIX. We allow it to be unset here so that an in-kernel 789 * interface may be written as a thin layer around shm, optionally not 790 * setting CLOEXEC. For shm_open(2), O_CLOEXEC is set unconditionally 791 * in sys_shm_open() to keep this implementation compliant. 792 */ 793 error = falloc_caps(td, &fp, &fd, flags & O_CLOEXEC, fcaps); 794 if (error) 795 return (error); 796 797 /* A SHM_ANON path pointer creates an anonymous object. */ 798 if (userpath == SHM_ANON) { 799 /* A read-only anonymous object is pointless. */ 800 if ((flags & O_ACCMODE) == O_RDONLY) { 801 fdclose(td, fp, fd); 802 fdrop(fp, td); 803 return (EINVAL); 804 } 805 shmfd = shm_alloc(td->td_ucred, cmode); 806 shmfd->shm_seals = initial_seals; 807 } else { 808 error = shm_copyin_path(td, userpath, &path); 809 if (error != 0) { 810 fdclose(td, fp, fd); 811 fdrop(fp, td); 812 return (error); 813 } 814 815 AUDIT_ARG_UPATH1_CANON(path); 816 fnv = fnv_32_str(path, FNV1_32_INIT); 817 sx_xlock(&shm_dict_lock); 818 shmfd = shm_lookup(path, fnv); 819 if (shmfd == NULL) { 820 /* Object does not yet exist, create it if requested. */ 821 if (flags & O_CREAT) { 822 #ifdef MAC 823 error = mac_posixshm_check_create(td->td_ucred, 824 path); 825 if (error == 0) { 826 #endif 827 shmfd = shm_alloc(td->td_ucred, cmode); 828 shmfd->shm_seals = initial_seals; 829 shm_insert(path, fnv, shmfd); 830 #ifdef MAC 831 } 832 #endif 833 } else { 834 free(path, M_SHMFD); 835 error = ENOENT; 836 } 837 } else { 838 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 839 &shmfd->shm_mtx); 840 841 /* 842 * kern_shm_open() likely shouldn't ever error out on 843 * trying to set a seal that already exists, unlike 844 * F_ADD_SEALS. This would break terribly as 845 * shm_open(2) actually sets F_SEAL_SEAL to maintain 846 * historical behavior where the underlying file could 847 * not be sealed. 848 */ 849 initial_seals &= ~shmfd->shm_seals; 850 851 /* 852 * Object already exists, obtain a new 853 * reference if requested and permitted. 854 */ 855 free(path, M_SHMFD); 856 857 /* 858 * initial_seals can't set additional seals if we've 859 * already been set F_SEAL_SEAL. If F_SEAL_SEAL is set, 860 * then we've already removed that one from 861 * initial_seals. This is currently redundant as we 862 * only allow setting F_SEAL_SEAL at creation time, but 863 * it's cheap to check and decreases the effort required 864 * to allow additional seals. 865 */ 866 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0 && 867 initial_seals != 0) 868 error = EPERM; 869 else if ((flags & (O_CREAT | O_EXCL)) == 870 (O_CREAT | O_EXCL)) 871 error = EEXIST; 872 else { 873 #ifdef MAC 874 error = mac_posixshm_check_open(td->td_ucred, 875 shmfd, FFLAGS(flags & O_ACCMODE)); 876 if (error == 0) 877 #endif 878 error = shm_access(shmfd, td->td_ucred, 879 FFLAGS(flags & O_ACCMODE)); 880 } 881 882 /* 883 * Truncate the file back to zero length if 884 * O_TRUNC was specified and the object was 885 * opened with read/write. 886 */ 887 if (error == 0 && 888 (flags & (O_ACCMODE | O_TRUNC)) == 889 (O_RDWR | O_TRUNC)) { 890 VM_OBJECT_WLOCK(shmfd->shm_object); 891 #ifdef MAC 892 error = mac_posixshm_check_truncate( 893 td->td_ucred, fp->f_cred, shmfd); 894 if (error == 0) 895 #endif 896 error = shm_dotruncate_locked(shmfd, 0, 897 rl_cookie); 898 VM_OBJECT_WUNLOCK(shmfd->shm_object); 899 } 900 if (error == 0) { 901 /* 902 * Currently we only allow F_SEAL_SEAL to be 903 * set initially. As noted above, this would 904 * need to be reworked should that change. 905 */ 906 shmfd->shm_seals |= initial_seals; 907 shm_hold(shmfd); 908 } 909 rangelock_unlock(&shmfd->shm_rl, rl_cookie, 910 &shmfd->shm_mtx); 911 } 912 sx_xunlock(&shm_dict_lock); 913 914 if (error) { 915 fdclose(td, fp, fd); 916 fdrop(fp, td); 917 return (error); 918 } 919 } 920 921 finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 922 923 td->td_retval[0] = fd; 924 fdrop(fp, td); 925 926 return (0); 927 } 928 929 /* System calls. */ 930 #ifdef COMPAT_FREEBSD12 931 int 932 freebsd12_shm_open(struct thread *td, struct freebsd12_shm_open_args *uap) 933 { 934 935 return (kern_shm_open(td, uap->path, uap->flags | O_CLOEXEC, 936 uap->mode, NULL)); 937 } 938 #endif 939 940 int 941 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 942 { 943 char *path; 944 Fnv32_t fnv; 945 int error; 946 947 error = shm_copyin_path(td, uap->path, &path); 948 if (error != 0) 949 return (error); 950 951 AUDIT_ARG_UPATH1_CANON(path); 952 fnv = fnv_32_str(path, FNV1_32_INIT); 953 sx_xlock(&shm_dict_lock); 954 error = shm_remove(path, fnv, td->td_ucred); 955 sx_xunlock(&shm_dict_lock); 956 free(path, M_TEMP); 957 958 return (error); 959 } 960 961 int 962 sys_shm_rename(struct thread *td, struct shm_rename_args *uap) 963 { 964 char *path_from = NULL, *path_to = NULL; 965 Fnv32_t fnv_from, fnv_to; 966 struct shmfd *fd_from; 967 struct shmfd *fd_to; 968 int error; 969 int flags; 970 971 flags = uap->flags; 972 AUDIT_ARG_FFLAGS(flags); 973 974 /* 975 * Make sure the user passed only valid flags. 976 * If you add a new flag, please add a new term here. 977 */ 978 if ((flags & ~( 979 SHM_RENAME_NOREPLACE | 980 SHM_RENAME_EXCHANGE 981 )) != 0) { 982 error = EINVAL; 983 goto out; 984 } 985 986 /* 987 * EXCHANGE and NOREPLACE don't quite make sense together. Let's 988 * force the user to choose one or the other. 989 */ 990 if ((flags & SHM_RENAME_NOREPLACE) != 0 && 991 (flags & SHM_RENAME_EXCHANGE) != 0) { 992 error = EINVAL; 993 goto out; 994 } 995 996 /* Renaming to or from anonymous makes no sense */ 997 if (uap->path_from == SHM_ANON || uap->path_to == SHM_ANON) { 998 error = EINVAL; 999 goto out; 1000 } 1001 1002 error = shm_copyin_path(td, uap->path_from, &path_from); 1003 if (error != 0) 1004 goto out; 1005 1006 error = shm_copyin_path(td, uap->path_to, &path_to); 1007 if (error != 0) 1008 goto out; 1009 1010 AUDIT_ARG_UPATH1_CANON(path_from); 1011 AUDIT_ARG_UPATH2_CANON(path_to); 1012 1013 /* Rename with from/to equal is a no-op */ 1014 if (strcmp(path_from, path_to) == 0) 1015 goto out; 1016 1017 fnv_from = fnv_32_str(path_from, FNV1_32_INIT); 1018 fnv_to = fnv_32_str(path_to, FNV1_32_INIT); 1019 1020 sx_xlock(&shm_dict_lock); 1021 1022 fd_from = shm_lookup(path_from, fnv_from); 1023 if (fd_from == NULL) { 1024 error = ENOENT; 1025 goto out_locked; 1026 } 1027 1028 fd_to = shm_lookup(path_to, fnv_to); 1029 if ((flags & SHM_RENAME_NOREPLACE) != 0 && fd_to != NULL) { 1030 error = EEXIST; 1031 goto out_locked; 1032 } 1033 1034 /* 1035 * Unconditionally prevents shm_remove from invalidating the 'from' 1036 * shm's state. 1037 */ 1038 shm_hold(fd_from); 1039 error = shm_remove(path_from, fnv_from, td->td_ucred); 1040 1041 /* 1042 * One of my assumptions failed if ENOENT (e.g. locking didn't 1043 * protect us) 1044 */ 1045 KASSERT(error != ENOENT, ("Our shm disappeared during shm_rename: %s", 1046 path_from)); 1047 if (error != 0) { 1048 shm_drop(fd_from); 1049 goto out_locked; 1050 } 1051 1052 /* 1053 * If we are exchanging, we need to ensure the shm_remove below 1054 * doesn't invalidate the dest shm's state. 1055 */ 1056 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) 1057 shm_hold(fd_to); 1058 1059 /* 1060 * NOTE: if path_to is not already in the hash, c'est la vie; 1061 * it simply means we have nothing already at path_to to unlink. 1062 * That is the ENOENT case. 1063 * 1064 * If we somehow don't have access to unlink this guy, but 1065 * did for the shm at path_from, then relink the shm to path_from 1066 * and abort with EACCES. 1067 * 1068 * All other errors: that is weird; let's relink and abort the 1069 * operation. 1070 */ 1071 error = shm_remove(path_to, fnv_to, td->td_ucred); 1072 if (error != 0 && error != ENOENT) { 1073 shm_insert(path_from, fnv_from, fd_from); 1074 shm_drop(fd_from); 1075 /* Don't free path_from now, since the hash references it */ 1076 path_from = NULL; 1077 goto out_locked; 1078 } 1079 1080 error = 0; 1081 1082 shm_insert(path_to, fnv_to, fd_from); 1083 1084 /* Don't free path_to now, since the hash references it */ 1085 path_to = NULL; 1086 1087 /* We kept a ref when we removed, and incremented again in insert */ 1088 shm_drop(fd_from); 1089 KASSERT(fd_from->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1090 fd_from->shm_refs)); 1091 1092 if ((flags & SHM_RENAME_EXCHANGE) != 0 && fd_to != NULL) { 1093 shm_insert(path_from, fnv_from, fd_to); 1094 path_from = NULL; 1095 shm_drop(fd_to); 1096 KASSERT(fd_to->shm_refs > 0, ("Expected >0 refs; got: %d\n", 1097 fd_to->shm_refs)); 1098 } 1099 1100 out_locked: 1101 sx_xunlock(&shm_dict_lock); 1102 1103 out: 1104 free(path_from, M_SHMFD); 1105 free(path_to, M_SHMFD); 1106 return (error); 1107 } 1108 1109 int 1110 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize, 1111 vm_prot_t prot, vm_prot_t cap_maxprot, int flags, 1112 vm_ooffset_t foff, struct thread *td) 1113 { 1114 struct shmfd *shmfd; 1115 vm_prot_t maxprot; 1116 int error; 1117 bool writecnt; 1118 void *rl_cookie; 1119 1120 shmfd = fp->f_data; 1121 maxprot = VM_PROT_NONE; 1122 1123 rl_cookie = rangelock_rlock(&shmfd->shm_rl, 0, objsize, 1124 &shmfd->shm_mtx); 1125 /* FREAD should always be set. */ 1126 if ((fp->f_flag & FREAD) != 0) 1127 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ; 1128 1129 /* 1130 * If FWRITE's set, we can allow VM_PROT_WRITE unless it's a shared 1131 * mapping with a write seal applied. 1132 */ 1133 if ((fp->f_flag & FWRITE) != 0 && ((flags & MAP_SHARED) == 0 || 1134 (shmfd->shm_seals & F_SEAL_WRITE) == 0)) 1135 maxprot |= VM_PROT_WRITE; 1136 1137 writecnt = (flags & MAP_SHARED) != 0 && (prot & VM_PROT_WRITE) != 0; 1138 1139 if (writecnt && (shmfd->shm_seals & F_SEAL_WRITE) != 0) { 1140 error = EPERM; 1141 goto out; 1142 } 1143 1144 /* Don't permit shared writable mappings on read-only descriptors. */ 1145 if (writecnt && (maxprot & VM_PROT_WRITE) == 0) { 1146 error = EACCES; 1147 goto out; 1148 } 1149 maxprot &= cap_maxprot; 1150 1151 /* See comment in vn_mmap(). */ 1152 if ( 1153 #ifdef _LP64 1154 objsize > OFF_MAX || 1155 #endif 1156 foff < 0 || foff > OFF_MAX - objsize) { 1157 error = EINVAL; 1158 goto out; 1159 } 1160 1161 #ifdef MAC 1162 error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags); 1163 if (error != 0) 1164 goto out; 1165 #endif 1166 1167 mtx_lock(&shm_timestamp_lock); 1168 vfs_timestamp(&shmfd->shm_atime); 1169 mtx_unlock(&shm_timestamp_lock); 1170 vm_object_reference(shmfd->shm_object); 1171 1172 if (writecnt) 1173 vm_pager_update_writecount(shmfd->shm_object, 0, objsize); 1174 error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags, 1175 shmfd->shm_object, foff, writecnt, td); 1176 if (error != 0) { 1177 if (writecnt) 1178 vm_pager_release_writecount(shmfd->shm_object, 0, 1179 objsize); 1180 vm_object_deallocate(shmfd->shm_object); 1181 } 1182 out: 1183 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1184 return (error); 1185 } 1186 1187 static int 1188 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 1189 struct thread *td) 1190 { 1191 struct shmfd *shmfd; 1192 int error; 1193 1194 error = 0; 1195 shmfd = fp->f_data; 1196 mtx_lock(&shm_timestamp_lock); 1197 /* 1198 * SUSv4 says that x bits of permission need not be affected. 1199 * Be consistent with our shm_open there. 1200 */ 1201 #ifdef MAC 1202 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 1203 if (error != 0) 1204 goto out; 1205 #endif 1206 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 1207 shmfd->shm_gid, VADMIN, active_cred, NULL); 1208 if (error != 0) 1209 goto out; 1210 shmfd->shm_mode = mode & ACCESSPERMS; 1211 out: 1212 mtx_unlock(&shm_timestamp_lock); 1213 return (error); 1214 } 1215 1216 static int 1217 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 1218 struct thread *td) 1219 { 1220 struct shmfd *shmfd; 1221 int error; 1222 1223 error = 0; 1224 shmfd = fp->f_data; 1225 mtx_lock(&shm_timestamp_lock); 1226 #ifdef MAC 1227 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 1228 if (error != 0) 1229 goto out; 1230 #endif 1231 if (uid == (uid_t)-1) 1232 uid = shmfd->shm_uid; 1233 if (gid == (gid_t)-1) 1234 gid = shmfd->shm_gid; 1235 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 1236 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 1237 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN))) 1238 goto out; 1239 shmfd->shm_uid = uid; 1240 shmfd->shm_gid = gid; 1241 out: 1242 mtx_unlock(&shm_timestamp_lock); 1243 return (error); 1244 } 1245 1246 /* 1247 * Helper routines to allow the backing object of a shared memory file 1248 * descriptor to be mapped in the kernel. 1249 */ 1250 int 1251 shm_map(struct file *fp, size_t size, off_t offset, void **memp) 1252 { 1253 struct shmfd *shmfd; 1254 vm_offset_t kva, ofs; 1255 vm_object_t obj; 1256 int rv; 1257 1258 if (fp->f_type != DTYPE_SHM) 1259 return (EINVAL); 1260 shmfd = fp->f_data; 1261 obj = shmfd->shm_object; 1262 VM_OBJECT_WLOCK(obj); 1263 /* 1264 * XXXRW: This validation is probably insufficient, and subject to 1265 * sign errors. It should be fixed. 1266 */ 1267 if (offset >= shmfd->shm_size || 1268 offset + size > round_page(shmfd->shm_size)) { 1269 VM_OBJECT_WUNLOCK(obj); 1270 return (EINVAL); 1271 } 1272 1273 shmfd->shm_kmappings++; 1274 vm_object_reference_locked(obj); 1275 VM_OBJECT_WUNLOCK(obj); 1276 1277 /* Map the object into the kernel_map and wire it. */ 1278 kva = vm_map_min(kernel_map); 1279 ofs = offset & PAGE_MASK; 1280 offset = trunc_page(offset); 1281 size = round_page(size + ofs); 1282 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1283 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1284 VM_PROT_READ | VM_PROT_WRITE, 0); 1285 if (rv == KERN_SUCCESS) { 1286 rv = vm_map_wire(kernel_map, kva, kva + size, 1287 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1288 if (rv == KERN_SUCCESS) { 1289 *memp = (void *)(kva + ofs); 1290 return (0); 1291 } 1292 vm_map_remove(kernel_map, kva, kva + size); 1293 } else 1294 vm_object_deallocate(obj); 1295 1296 /* On failure, drop our mapping reference. */ 1297 VM_OBJECT_WLOCK(obj); 1298 shmfd->shm_kmappings--; 1299 VM_OBJECT_WUNLOCK(obj); 1300 1301 return (vm_mmap_to_errno(rv)); 1302 } 1303 1304 /* 1305 * We require the caller to unmap the entire entry. This allows us to 1306 * safely decrement shm_kmappings when a mapping is removed. 1307 */ 1308 int 1309 shm_unmap(struct file *fp, void *mem, size_t size) 1310 { 1311 struct shmfd *shmfd; 1312 vm_map_entry_t entry; 1313 vm_offset_t kva, ofs; 1314 vm_object_t obj; 1315 vm_pindex_t pindex; 1316 vm_prot_t prot; 1317 boolean_t wired; 1318 vm_map_t map; 1319 int rv; 1320 1321 if (fp->f_type != DTYPE_SHM) 1322 return (EINVAL); 1323 shmfd = fp->f_data; 1324 kva = (vm_offset_t)mem; 1325 ofs = kva & PAGE_MASK; 1326 kva = trunc_page(kva); 1327 size = round_page(size + ofs); 1328 map = kernel_map; 1329 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1330 &obj, &pindex, &prot, &wired); 1331 if (rv != KERN_SUCCESS) 1332 return (EINVAL); 1333 if (entry->start != kva || entry->end != kva + size) { 1334 vm_map_lookup_done(map, entry); 1335 return (EINVAL); 1336 } 1337 vm_map_lookup_done(map, entry); 1338 if (obj != shmfd->shm_object) 1339 return (EINVAL); 1340 vm_map_remove(map, kva, kva + size); 1341 VM_OBJECT_WLOCK(obj); 1342 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1343 shmfd->shm_kmappings--; 1344 VM_OBJECT_WUNLOCK(obj); 1345 return (0); 1346 } 1347 1348 static int 1349 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list) 1350 { 1351 const char *path, *pr_path; 1352 size_t pr_pathlen; 1353 bool visible; 1354 1355 sx_assert(&shm_dict_lock, SA_LOCKED); 1356 kif->kf_type = KF_TYPE_SHM; 1357 kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode; 1358 kif->kf_un.kf_file.kf_file_size = shmfd->shm_size; 1359 if (shmfd->shm_path != NULL) { 1360 if (shmfd->shm_path != NULL) { 1361 path = shmfd->shm_path; 1362 pr_path = curthread->td_ucred->cr_prison->pr_path; 1363 if (strcmp(pr_path, "/") != 0) { 1364 /* Return the jail-rooted pathname. */ 1365 pr_pathlen = strlen(pr_path); 1366 visible = strncmp(path, pr_path, pr_pathlen) 1367 == 0 && path[pr_pathlen] == '/'; 1368 if (list && !visible) 1369 return (EPERM); 1370 if (visible) 1371 path += pr_pathlen; 1372 } 1373 strlcpy(kif->kf_path, path, sizeof(kif->kf_path)); 1374 } 1375 } 1376 return (0); 1377 } 1378 1379 static int 1380 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif, 1381 struct filedesc *fdp __unused) 1382 { 1383 int res; 1384 1385 sx_slock(&shm_dict_lock); 1386 res = shm_fill_kinfo_locked(fp->f_data, kif, false); 1387 sx_sunlock(&shm_dict_lock); 1388 return (res); 1389 } 1390 1391 static int 1392 shm_add_seals(struct file *fp, int seals) 1393 { 1394 struct shmfd *shmfd; 1395 void *rl_cookie; 1396 vm_ooffset_t writemappings; 1397 int error, nseals; 1398 1399 error = 0; 1400 shmfd = fp->f_data; 1401 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 1402 &shmfd->shm_mtx); 1403 1404 /* Even already-set seals should result in EPERM. */ 1405 if ((shmfd->shm_seals & F_SEAL_SEAL) != 0) { 1406 error = EPERM; 1407 goto out; 1408 } 1409 nseals = seals & ~shmfd->shm_seals; 1410 if ((nseals & F_SEAL_WRITE) != 0) { 1411 /* 1412 * The rangelock above prevents writable mappings from being 1413 * added after we've started applying seals. The RLOCK here 1414 * is to avoid torn reads on ILP32 arches as unmapping/reducing 1415 * writemappings will be done without a rangelock. 1416 */ 1417 VM_OBJECT_RLOCK(shmfd->shm_object); 1418 writemappings = shmfd->shm_object->un_pager.swp.writemappings; 1419 VM_OBJECT_RUNLOCK(shmfd->shm_object); 1420 /* kmappings are also writable */ 1421 if (writemappings > 0) { 1422 error = EBUSY; 1423 goto out; 1424 } 1425 } 1426 shmfd->shm_seals |= nseals; 1427 out: 1428 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1429 return (error); 1430 } 1431 1432 static int 1433 shm_get_seals(struct file *fp, int *seals) 1434 { 1435 struct shmfd *shmfd; 1436 1437 shmfd = fp->f_data; 1438 *seals = shmfd->shm_seals; 1439 return (0); 1440 } 1441 1442 static int 1443 shm_fallocate(struct file *fp, off_t offset, off_t len, struct thread *td) 1444 { 1445 void *rl_cookie; 1446 struct shmfd *shmfd; 1447 size_t size; 1448 int error; 1449 1450 /* This assumes that the caller already checked for overflow. */ 1451 error = 0; 1452 shmfd = fp->f_data; 1453 size = offset + len; 1454 1455 /* 1456 * Just grab the rangelock for the range that we may be attempting to 1457 * grow, rather than blocking read/write for regions we won't be 1458 * touching while this (potential) resize is in progress. Other 1459 * attempts to resize the shmfd will have to take a write lock from 0 to 1460 * OFF_MAX, so this being potentially beyond the current usable range of 1461 * the shmfd is not necessarily a concern. If other mechanisms are 1462 * added to grow a shmfd, this may need to be re-evaluated. 1463 */ 1464 rl_cookie = rangelock_wlock(&shmfd->shm_rl, offset, size, 1465 &shmfd->shm_mtx); 1466 if (size > shmfd->shm_size) { 1467 VM_OBJECT_WLOCK(shmfd->shm_object); 1468 error = shm_dotruncate_locked(shmfd, size, rl_cookie); 1469 VM_OBJECT_WUNLOCK(shmfd->shm_object); 1470 } 1471 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 1472 /* Translate to posix_fallocate(2) return value as needed. */ 1473 if (error == ENOMEM) 1474 error = ENOSPC; 1475 return (error); 1476 } 1477 1478 static int 1479 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS) 1480 { 1481 struct shm_mapping *shmm; 1482 struct sbuf sb; 1483 struct kinfo_file kif; 1484 u_long i; 1485 ssize_t curlen; 1486 int error, error2; 1487 1488 sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req); 1489 sbuf_clear_flags(&sb, SBUF_INCLUDENUL); 1490 curlen = 0; 1491 error = 0; 1492 sx_slock(&shm_dict_lock); 1493 for (i = 0; i < shm_hash + 1; i++) { 1494 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) { 1495 error = shm_fill_kinfo_locked(shmm->sm_shmfd, 1496 &kif, true); 1497 if (error == EPERM) 1498 continue; 1499 if (error != 0) 1500 break; 1501 pack_kinfo(&kif); 1502 if (req->oldptr != NULL && 1503 kif.kf_structsize + curlen > req->oldlen) 1504 break; 1505 error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ? 1506 0 : ENOMEM; 1507 if (error != 0) 1508 break; 1509 curlen += kif.kf_structsize; 1510 } 1511 } 1512 sx_sunlock(&shm_dict_lock); 1513 error2 = sbuf_finish(&sb); 1514 sbuf_delete(&sb); 1515 return (error != 0 ? error : error2); 1516 } 1517 1518 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list, 1519 CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE, 1520 NULL, 0, sysctl_posix_shm_list, "", 1521 "POSIX SHM list"); 1522 1523 int 1524 kern_shm_open(struct thread *td, const char *path, int flags, mode_t mode, 1525 struct filecaps *caps) 1526 { 1527 1528 return (kern_shm_open2(td, path, flags, mode, 0, caps, NULL)); 1529 } 1530 1531 /* 1532 * This version of the shm_open() interface leaves CLOEXEC behavior up to the 1533 * caller, and libc will enforce it for the traditional shm_open() call. This 1534 * allows other consumers, like memfd_create(), to opt-in for CLOEXEC. This 1535 * interface also includes a 'name' argument that is currently unused, but could 1536 * potentially be exported later via some interface for debugging purposes. 1537 * From the kernel's perspective, it is optional. Individual consumers like 1538 * memfd_create() may require it in order to be compatible with other systems 1539 * implementing the same function. 1540 */ 1541 int 1542 sys_shm_open2(struct thread *td, struct shm_open2_args *uap) 1543 { 1544 1545 return (kern_shm_open2(td, uap->path, uap->flags, uap->mode, 1546 uap->shmflags, NULL, uap->name)); 1547 } 1548