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