1/*- 2 * Copyright (c) 2006, 2011 Robert N. M. Watson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27/* 28 * Support for shared swap-backed anonymous memory objects via 29 * shm_open(2) and shm_unlink(2). While most of the implementation is 30 * here, vm_mmap.c contains mapping logic changes. 31 * 32 * TODO: 33 * 34 * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) 35 * and ipcrm(1) be expanded or should new tools to manage both POSIX 36 * kernel semaphores and POSIX shared memory be written? 37 * 38 * (2) Add support for this file type to fstat(1). 39 * 40 * (3) Resource limits? Does this need its own resource limits or are the 41 * existing limits in mmap(2) sufficient? 42 */ 43 44#include <sys/cdefs.h> 45__FBSDID("$FreeBSD: stable/10/sys/kern/uipc_shm.c 325783 2017-11-13 23:21:17Z jamie $"); 46 47#include "opt_capsicum.h" 48#include "opt_ktrace.h" 49 50#include <sys/param.h> 51#include <sys/capsicum.h> 52#include <sys/conf.h> 53#include <sys/fcntl.h> 54#include <sys/file.h> 55#include <sys/filedesc.h> 56#include <sys/fnv_hash.h> 57#include <sys/kernel.h> 58#include <sys/uio.h> 59#include <sys/signal.h> 60#include <sys/jail.h> 61#include <sys/ktrace.h> 62#include <sys/lock.h> 63#include <sys/malloc.h> 64#include <sys/mman.h> 65#include <sys/mutex.h> 66#include <sys/priv.h> 67#include <sys/proc.h> 68#include <sys/refcount.h> 69#include <sys/resourcevar.h> 70#include <sys/rwlock.h> 71#include <sys/stat.h> 72#include <sys/sysctl.h> 73#include <sys/sysproto.h> 74#include <sys/systm.h> 75#include <sys/sx.h> 76#include <sys/time.h> 77#include <sys/vnode.h> 78#include <sys/unistd.h> 79 80#include <security/mac/mac_framework.h> 81 82#include <vm/vm.h> 83#include <vm/vm_param.h> 84#include <vm/pmap.h> 85#include <vm/vm_extern.h> 86#include <vm/vm_map.h> 87#include <vm/vm_kern.h> 88#include <vm/vm_object.h> 89#include <vm/vm_page.h> 90#include <vm/vm_pageout.h> 91#include <vm/vm_pager.h> 92#include <vm/swap_pager.h> 93 94struct shm_mapping { 95 char *sm_path; 96 Fnv32_t sm_fnv; 97 struct shmfd *sm_shmfd; 98 LIST_ENTRY(shm_mapping) sm_link; 99}; 100 101static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); 102static LIST_HEAD(, shm_mapping) *shm_dictionary; 103static struct sx shm_dict_lock; 104static struct mtx shm_timestamp_lock; 105static u_long shm_hash; 106static struct unrhdr *shm_ino_unr; 107static dev_t shm_dev_ino; 108 109#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) 110 111static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags); 112static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode); 113static void shm_init(void *arg); 114static void shm_drop(struct shmfd *shmfd); 115static struct shmfd *shm_hold(struct shmfd *shmfd); 116static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); 117static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); 118static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 119static int shm_dotruncate(struct shmfd *shmfd, off_t length); 120 121static fo_rdwr_t shm_read; 122static fo_rdwr_t shm_write; 123static fo_truncate_t shm_truncate; 124static fo_ioctl_t shm_ioctl; 125static fo_poll_t shm_poll; 126static fo_kqfilter_t shm_kqfilter; 127static fo_stat_t shm_stat; 128static fo_close_t shm_close; 129static fo_chmod_t shm_chmod; 130static fo_chown_t shm_chown; 131static fo_seek_t shm_seek; 132 133/* File descriptor operations. */ 134static struct fileops shm_ops = { 135 .fo_read = shm_read, 136 .fo_write = shm_write, 137 .fo_truncate = shm_truncate, 138 .fo_ioctl = shm_ioctl, 139 .fo_poll = shm_poll, 140 .fo_kqfilter = shm_kqfilter, 141 .fo_stat = shm_stat, 142 .fo_close = shm_close, 143 .fo_chmod = shm_chmod, 144 .fo_chown = shm_chown, 145 .fo_sendfile = vn_sendfile, 146 .fo_seek = shm_seek, 147 .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE 148}; 149 150FEATURE(posix_shm, "POSIX shared memory"); 151 152static int 153uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio) 154{ 155 vm_page_t m; 156 vm_pindex_t idx; 157 size_t tlen; 158 int error, offset, rv; 159 160 idx = OFF_TO_IDX(uio->uio_offset); 161 offset = uio->uio_offset & PAGE_MASK; 162 tlen = MIN(PAGE_SIZE - offset, len); 163 164 VM_OBJECT_WLOCK(obj); 165 166 /* 167 * Parallel reads of the page content from disk are prevented 168 * by exclusive busy. 169 * 170 * Although the tmpfs vnode lock is held here, it is 171 * nonetheless safe to sleep waiting for a free page. The 172 * pageout daemon does not need to acquire the tmpfs vnode 173 * lock to page out tobj's pages because tobj is a OBJT_SWAP 174 * type object. 175 */ 176 m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL); 177 if (m->valid != VM_PAGE_BITS_ALL) { 178 if (vm_pager_has_page(obj, idx, NULL, NULL)) { 179 rv = vm_pager_get_pages(obj, &m, 1, 0); 180 m = vm_page_lookup(obj, idx); 181 if (m == NULL) { 182 printf( 183 "uiomove_object: vm_obj %p idx %jd null lookup rv %d\n", 184 obj, idx, rv); 185 VM_OBJECT_WUNLOCK(obj); 186 return (EIO); 187 } 188 if (rv != VM_PAGER_OK) { 189 printf( 190 "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n", 191 obj, idx, m->valid, rv); 192 vm_page_lock(m); 193 vm_page_free(m); 194 vm_page_unlock(m); 195 VM_OBJECT_WUNLOCK(obj); 196 return (EIO); 197 } 198 } else 199 vm_page_zero_invalid(m, TRUE); 200 } 201 vm_page_xunbusy(m); 202 vm_page_lock(m); 203 vm_page_hold(m); 204 if (m->queue == PQ_NONE) { 205 vm_page_deactivate(m); 206 } else { 207 /* Requeue to maintain LRU ordering. */ 208 vm_page_requeue(m); 209 } 210 vm_page_unlock(m); 211 VM_OBJECT_WUNLOCK(obj); 212 error = uiomove_fromphys(&m, offset, tlen, uio); 213 if (uio->uio_rw == UIO_WRITE && error == 0) { 214 VM_OBJECT_WLOCK(obj); 215 vm_page_dirty(m); 216 vm_pager_page_unswapped(m); 217 VM_OBJECT_WUNLOCK(obj); 218 } 219 vm_page_lock(m); 220 vm_page_unhold(m); 221 vm_page_unlock(m); 222 223 return (error); 224} 225 226int 227uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio) 228{ 229 ssize_t resid; 230 size_t len; 231 int error; 232 233 error = 0; 234 while ((resid = uio->uio_resid) > 0) { 235 if (obj_size <= uio->uio_offset) 236 break; 237 len = MIN(obj_size - uio->uio_offset, resid); 238 if (len == 0) 239 break; 240 error = uiomove_object_page(obj, len, uio); 241 if (error != 0 || resid == uio->uio_resid) 242 break; 243 } 244 return (error); 245} 246 247static int 248shm_seek(struct file *fp, off_t offset, int whence, struct thread *td) 249{ 250 struct shmfd *shmfd; 251 off_t foffset; 252 int error; 253 254 shmfd = fp->f_data; 255 foffset = foffset_lock(fp, 0); 256 error = 0; 257 switch (whence) { 258 case L_INCR: 259 if (foffset < 0 || 260 (offset > 0 && foffset > OFF_MAX - offset)) { 261 error = EOVERFLOW; 262 break; 263 } 264 offset += foffset; 265 break; 266 case L_XTND: 267 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) { 268 error = EOVERFLOW; 269 break; 270 } 271 offset += shmfd->shm_size; 272 break; 273 case L_SET: 274 break; 275 default: 276 error = EINVAL; 277 } 278 if (error == 0) { 279 if (offset < 0 || offset > shmfd->shm_size) 280 error = EINVAL; 281 else 282 *(off_t *)(td->td_retval) = offset; 283 } 284 foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0); 285 return (error); 286} 287 288static int 289shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 290 int flags, struct thread *td) 291{ 292 struct shmfd *shmfd; 293 void *rl_cookie; 294 int error; 295 296 shmfd = fp->f_data; 297#ifdef MAC 298 error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd); 299 if (error) 300 return (error); 301#endif 302 foffset_lock_uio(fp, uio, flags); 303 rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset, 304 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 305 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 306 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 307 foffset_unlock_uio(fp, uio, flags); 308 return (error); 309} 310 311static int 312shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 313 int flags, struct thread *td) 314{ 315 struct shmfd *shmfd; 316 void *rl_cookie; 317 int error; 318 319 shmfd = fp->f_data; 320#ifdef MAC 321 error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd); 322 if (error) 323 return (error); 324#endif 325 foffset_lock_uio(fp, uio, flags); 326 if ((flags & FOF_OFFSET) == 0) { 327 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX, 328 &shmfd->shm_mtx); 329 } else { 330 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset, 331 uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx); 332 } 333 334 error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio); 335 rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx); 336 foffset_unlock_uio(fp, uio, flags); 337 return (error); 338} 339 340static int 341shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, 342 struct thread *td) 343{ 344 struct shmfd *shmfd; 345#ifdef MAC 346 int error; 347#endif 348 349 shmfd = fp->f_data; 350#ifdef MAC 351 error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); 352 if (error) 353 return (error); 354#endif 355 return (shm_dotruncate(shmfd, length)); 356} 357 358static int 359shm_ioctl(struct file *fp, u_long com, void *data, 360 struct ucred *active_cred, struct thread *td) 361{ 362 363 return (EOPNOTSUPP); 364} 365 366static int 367shm_poll(struct file *fp, int events, struct ucred *active_cred, 368 struct thread *td) 369{ 370 371 return (EOPNOTSUPP); 372} 373 374static int 375shm_kqfilter(struct file *fp, struct knote *kn) 376{ 377 378 return (EOPNOTSUPP); 379} 380 381static int 382shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 383 struct thread *td) 384{ 385 struct shmfd *shmfd; 386#ifdef MAC 387 int error; 388#endif 389 390 shmfd = fp->f_data; 391 392#ifdef MAC 393 error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); 394 if (error) 395 return (error); 396#endif 397 398 /* 399 * Attempt to return sanish values for fstat() on a memory file 400 * descriptor. 401 */ 402 bzero(sb, sizeof(*sb)); 403 sb->st_blksize = PAGE_SIZE; 404 sb->st_size = shmfd->shm_size; 405 sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; 406 mtx_lock(&shm_timestamp_lock); 407 sb->st_atim = shmfd->shm_atime; 408 sb->st_ctim = shmfd->shm_ctime; 409 sb->st_mtim = shmfd->shm_mtime; 410 sb->st_birthtim = shmfd->shm_birthtime; 411 sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ 412 sb->st_uid = shmfd->shm_uid; 413 sb->st_gid = shmfd->shm_gid; 414 mtx_unlock(&shm_timestamp_lock); 415 sb->st_dev = shm_dev_ino; 416 sb->st_ino = shmfd->shm_ino; 417 418 return (0); 419} 420 421static int 422shm_close(struct file *fp, struct thread *td) 423{ 424 struct shmfd *shmfd; 425 426 shmfd = fp->f_data; 427 fp->f_data = NULL; 428 shm_drop(shmfd); 429 430 return (0); 431} 432 433static int 434shm_dotruncate(struct shmfd *shmfd, off_t length) 435{ 436 vm_object_t object; 437 vm_page_t m, ma[1]; 438 vm_pindex_t idx, nobjsize; 439 vm_ooffset_t delta; 440 int base, rv; 441 442 KASSERT(length >= 0, ("shm_dotruncate: length < 0")); 443 object = shmfd->shm_object; 444 VM_OBJECT_WLOCK(object); 445 if (length == shmfd->shm_size) { 446 VM_OBJECT_WUNLOCK(object); 447 return (0); 448 } 449 nobjsize = OFF_TO_IDX(length + PAGE_MASK); 450 451 /* Are we shrinking? If so, trim the end. */ 452 if (length < shmfd->shm_size) { 453 /* 454 * Disallow any requests to shrink the size if this 455 * object is mapped into the kernel. 456 */ 457 if (shmfd->shm_kmappings > 0) { 458 VM_OBJECT_WUNLOCK(object); 459 return (EBUSY); 460 } 461 462 /* 463 * Zero the truncated part of the last page. 464 */ 465 base = length & PAGE_MASK; 466 if (base != 0) { 467 idx = OFF_TO_IDX(length); 468retry: 469 m = vm_page_lookup(object, idx); 470 if (m != NULL) { 471 if (vm_page_sleep_if_busy(m, "shmtrc")) 472 goto retry; 473 } else if (vm_pager_has_page(object, idx, NULL, NULL)) { 474 m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); 475 if (m == NULL) { 476 VM_OBJECT_WUNLOCK(object); 477 VM_WAIT; 478 VM_OBJECT_WLOCK(object); 479 goto retry; 480 } else if (m->valid != VM_PAGE_BITS_ALL) { 481 ma[0] = m; 482 rv = vm_pager_get_pages(object, ma, 1, 483 0); 484 m = vm_page_lookup(object, idx); 485 } else 486 /* A cached page was reactivated. */ 487 rv = VM_PAGER_OK; 488 vm_page_lock(m); 489 if (rv == VM_PAGER_OK) { 490 vm_page_deactivate(m); 491 vm_page_unlock(m); 492 vm_page_xunbusy(m); 493 } else { 494 vm_page_free(m); 495 vm_page_unlock(m); 496 VM_OBJECT_WUNLOCK(object); 497 return (EIO); 498 } 499 } 500 if (m != NULL) { 501 pmap_zero_page_area(m, base, PAGE_SIZE - base); 502 KASSERT(m->valid == VM_PAGE_BITS_ALL, 503 ("shm_dotruncate: page %p is invalid", m)); 504 vm_page_dirty(m); 505 vm_pager_page_unswapped(m); 506 } 507 } 508 delta = IDX_TO_OFF(object->size - nobjsize); 509 510 /* Toss in memory pages. */ 511 if (nobjsize < object->size) 512 vm_object_page_remove(object, nobjsize, object->size, 513 0); 514 515 /* Toss pages from swap. */ 516 if (object->type == OBJT_SWAP) 517 swap_pager_freespace(object, nobjsize, delta); 518 519 /* Free the swap accounted for shm */ 520 swap_release_by_cred(delta, object->cred); 521 object->charge -= delta; 522 } else { 523 /* Try to reserve additional swap space. */ 524 delta = IDX_TO_OFF(nobjsize - object->size); 525 if (!swap_reserve_by_cred(delta, object->cred)) { 526 VM_OBJECT_WUNLOCK(object); 527 return (ENOMEM); 528 } 529 object->charge += delta; 530 } 531 shmfd->shm_size = length; 532 mtx_lock(&shm_timestamp_lock); 533 vfs_timestamp(&shmfd->shm_ctime); 534 shmfd->shm_mtime = shmfd->shm_ctime; 535 mtx_unlock(&shm_timestamp_lock); 536 object->size = nobjsize; 537 VM_OBJECT_WUNLOCK(object); 538 return (0); 539} 540 541/* 542 * shmfd object management including creation and reference counting 543 * routines. 544 */ 545static struct shmfd * 546shm_alloc(struct ucred *ucred, mode_t mode) 547{ 548 struct shmfd *shmfd; 549 int ino; 550 551 shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); 552 shmfd->shm_size = 0; 553 shmfd->shm_uid = ucred->cr_uid; 554 shmfd->shm_gid = ucred->cr_gid; 555 shmfd->shm_mode = mode; 556 shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, 557 shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); 558 KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); 559 shmfd->shm_object->pg_color = 0; 560 VM_OBJECT_WLOCK(shmfd->shm_object); 561 vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); 562 vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT); 563 VM_OBJECT_WUNLOCK(shmfd->shm_object); 564 vfs_timestamp(&shmfd->shm_birthtime); 565 shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = 566 shmfd->shm_birthtime; 567 ino = alloc_unr(shm_ino_unr); 568 if (ino == -1) 569 shmfd->shm_ino = 0; 570 else 571 shmfd->shm_ino = ino; 572 refcount_init(&shmfd->shm_refs, 1); 573 mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF); 574 rangelock_init(&shmfd->shm_rl); 575#ifdef MAC 576 mac_posixshm_init(shmfd); 577 mac_posixshm_create(ucred, shmfd); 578#endif 579 580 return (shmfd); 581} 582 583static struct shmfd * 584shm_hold(struct shmfd *shmfd) 585{ 586 587 refcount_acquire(&shmfd->shm_refs); 588 return (shmfd); 589} 590 591static void 592shm_drop(struct shmfd *shmfd) 593{ 594 595 if (refcount_release(&shmfd->shm_refs)) { 596#ifdef MAC 597 mac_posixshm_destroy(shmfd); 598#endif 599 rangelock_destroy(&shmfd->shm_rl); 600 mtx_destroy(&shmfd->shm_mtx); 601 vm_object_deallocate(shmfd->shm_object); 602 if (shmfd->shm_ino != 0) 603 free_unr(shm_ino_unr, shmfd->shm_ino); 604 free(shmfd, M_SHMFD); 605 } 606} 607 608/* 609 * Determine if the credentials have sufficient permissions for a 610 * specified combination of FREAD and FWRITE. 611 */ 612static int 613shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) 614{ 615 accmode_t accmode; 616 int error; 617 618 accmode = 0; 619 if (flags & FREAD) 620 accmode |= VREAD; 621 if (flags & FWRITE) 622 accmode |= VWRITE; 623 mtx_lock(&shm_timestamp_lock); 624 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, 625 accmode, ucred, NULL); 626 mtx_unlock(&shm_timestamp_lock); 627 return (error); 628} 629 630/* 631 * Dictionary management. We maintain an in-kernel dictionary to map 632 * paths to shmfd objects. We use the FNV hash on the path to store 633 * the mappings in a hash table. 634 */ 635static void 636shm_init(void *arg) 637{ 638 639 mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); 640 sx_init(&shm_dict_lock, "shm dictionary"); 641 shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); 642 shm_ino_unr = new_unrhdr(1, INT32_MAX, NULL); 643 KASSERT(shm_ino_unr != NULL, ("shm fake inodes not initialized")); 644 shm_dev_ino = devfs_alloc_cdp_inode(); 645 KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized")); 646} 647SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL); 648 649static struct shmfd * 650shm_lookup(char *path, Fnv32_t fnv) 651{ 652 struct shm_mapping *map; 653 654 LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { 655 if (map->sm_fnv != fnv) 656 continue; 657 if (strcmp(map->sm_path, path) == 0) 658 return (map->sm_shmfd); 659 } 660 661 return (NULL); 662} 663 664static void 665shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) 666{ 667 struct shm_mapping *map; 668 669 map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); 670 map->sm_path = path; 671 map->sm_fnv = fnv; 672 map->sm_shmfd = shm_hold(shmfd); 673 shmfd->shm_path = path; 674 LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); 675} 676 677static int 678shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 679{ 680 struct shm_mapping *map; 681 int error; 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#ifdef MAC 688 error = mac_posixshm_check_unlink(ucred, map->sm_shmfd); 689 if (error) 690 return (error); 691#endif 692 error = shm_access(map->sm_shmfd, ucred, 693 FREAD | FWRITE); 694 if (error) 695 return (error); 696 map->sm_shmfd->shm_path = NULL; 697 LIST_REMOVE(map, sm_link); 698 shm_drop(map->sm_shmfd); 699 free(map->sm_path, M_SHMFD); 700 free(map, M_SHMFD); 701 return (0); 702 } 703 } 704 705 return (ENOENT); 706} 707 708/* System calls. */ 709int 710sys_shm_open(struct thread *td, struct shm_open_args *uap) 711{ 712 struct filedesc *fdp; 713 struct shmfd *shmfd; 714 struct file *fp; 715 char *path; 716 const char *pr_path; 717 size_t pr_pathlen; 718 Fnv32_t fnv; 719 mode_t cmode; 720 int fd, error; 721 722#ifdef CAPABILITY_MODE 723 /* 724 * shm_open(2) is only allowed for anonymous objects. 725 */ 726 if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON)) 727 return (ECAPMODE); 728#endif 729 730 if ((uap->flags & O_ACCMODE) != O_RDONLY && 731 (uap->flags & O_ACCMODE) != O_RDWR) 732 return (EINVAL); 733 734 if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0) 735 return (EINVAL); 736 737 fdp = td->td_proc->p_fd; 738 cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS; 739 740 error = falloc(td, &fp, &fd, O_CLOEXEC); 741 if (error) 742 return (error); 743 744 /* A SHM_ANON path pointer creates an anonymous object. */ 745 if (uap->path == SHM_ANON) { 746 /* A read-only anonymous object is pointless. */ 747 if ((uap->flags & O_ACCMODE) == O_RDONLY) { 748 fdclose(td, fp, fd); 749 fdrop(fp, td); 750 return (EINVAL); 751 } 752 shmfd = shm_alloc(td->td_ucred, cmode); 753 } else { 754 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK); 755 pr_path = td->td_ucred->cr_prison->pr_path; 756 757 /* Construct a full pathname for jailed callers. */ 758 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 759 : strlcpy(path, pr_path, MAXPATHLEN); 760 error = copyinstr(uap->path, path + pr_pathlen, 761 MAXPATHLEN - pr_pathlen, NULL); 762#ifdef KTRACE 763 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI)) 764 ktrnamei(path); 765#endif 766 /* Require paths to start with a '/' character. */ 767 if (error == 0 && path[pr_pathlen] != '/') 768 error = EINVAL; 769 if (error) { 770 fdclose(td, fp, fd); 771 fdrop(fp, td); 772 free(path, M_SHMFD); 773 return (error); 774 } 775 776 fnv = fnv_32_str(path, FNV1_32_INIT); 777 sx_xlock(&shm_dict_lock); 778 shmfd = shm_lookup(path, fnv); 779 if (shmfd == NULL) { 780 /* Object does not yet exist, create it if requested. */ 781 if (uap->flags & O_CREAT) { 782#ifdef MAC 783 error = mac_posixshm_check_create(td->td_ucred, 784 path); 785 if (error == 0) { 786#endif 787 shmfd = shm_alloc(td->td_ucred, cmode); 788 shm_insert(path, fnv, shmfd); 789#ifdef MAC 790 } 791#endif 792 } else { 793 free(path, M_SHMFD); 794 error = ENOENT; 795 } 796 } else { 797 /* 798 * Object already exists, obtain a new 799 * reference if requested and permitted. 800 */ 801 free(path, M_SHMFD); 802 if ((uap->flags & (O_CREAT | O_EXCL)) == 803 (O_CREAT | O_EXCL)) 804 error = EEXIST; 805 else { 806#ifdef MAC 807 error = mac_posixshm_check_open(td->td_ucred, 808 shmfd, FFLAGS(uap->flags & O_ACCMODE)); 809 if (error == 0) 810#endif 811 error = shm_access(shmfd, td->td_ucred, 812 FFLAGS(uap->flags & O_ACCMODE)); 813 } 814 815 /* 816 * Truncate the file back to zero length if 817 * O_TRUNC was specified and the object was 818 * opened with read/write. 819 */ 820 if (error == 0 && 821 (uap->flags & (O_ACCMODE | O_TRUNC)) == 822 (O_RDWR | O_TRUNC)) { 823#ifdef MAC 824 error = mac_posixshm_check_truncate( 825 td->td_ucred, fp->f_cred, shmfd); 826 if (error == 0) 827#endif 828 shm_dotruncate(shmfd, 0); 829 } 830 if (error == 0) 831 shm_hold(shmfd); 832 } 833 sx_xunlock(&shm_dict_lock); 834 835 if (error) { 836 fdclose(td, fp, fd); 837 fdrop(fp, td); 838 return (error); 839 } 840 } 841 842 finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops); 843 844 td->td_retval[0] = fd; 845 fdrop(fp, td); 846 847 return (0); 848} 849 850int 851sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap) 852{ 853 char *path; 854 const char *pr_path; 855 size_t pr_pathlen; 856 Fnv32_t fnv; 857 int error; 858 859 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 860 pr_path = td->td_ucred->cr_prison->pr_path; 861 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0 862 : strlcpy(path, pr_path, MAXPATHLEN); 863 error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen, 864 NULL); 865 if (error) { 866 free(path, M_TEMP); 867 return (error); 868 } 869#ifdef KTRACE 870 if (KTRPOINT(curthread, KTR_NAMEI)) 871 ktrnamei(path); 872#endif 873 fnv = fnv_32_str(path, FNV1_32_INIT); 874 sx_xlock(&shm_dict_lock); 875 error = shm_remove(path, fnv, td->td_ucred); 876 sx_xunlock(&shm_dict_lock); 877 free(path, M_TEMP); 878 879 return (error); 880} 881 882/* 883 * mmap() helper to validate mmap() requests against shm object state 884 * and give mmap() the vm_object to use for the mapping. 885 */ 886int 887shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff, 888 vm_object_t *obj) 889{ 890 891 /* 892 * XXXRW: This validation is probably insufficient, and subject to 893 * sign errors. It should be fixed. 894 */ 895 if (foff >= shmfd->shm_size || 896 foff + objsize > round_page(shmfd->shm_size)) 897 return (EINVAL); 898 899 mtx_lock(&shm_timestamp_lock); 900 vfs_timestamp(&shmfd->shm_atime); 901 mtx_unlock(&shm_timestamp_lock); 902 vm_object_reference(shmfd->shm_object); 903 *obj = shmfd->shm_object; 904 return (0); 905} 906 907static int 908shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred, 909 struct thread *td) 910{ 911 struct shmfd *shmfd; 912 int error; 913 914 error = 0; 915 shmfd = fp->f_data; 916 mtx_lock(&shm_timestamp_lock); 917 /* 918 * SUSv4 says that x bits of permission need not be affected. 919 * Be consistent with our shm_open there. 920 */ 921#ifdef MAC 922 error = mac_posixshm_check_setmode(active_cred, shmfd, mode); 923 if (error != 0) 924 goto out; 925#endif 926 error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, 927 shmfd->shm_gid, VADMIN, active_cred, NULL); 928 if (error != 0) 929 goto out; 930 shmfd->shm_mode = mode & ACCESSPERMS; 931out: 932 mtx_unlock(&shm_timestamp_lock); 933 return (error); 934} 935 936static int 937shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred, 938 struct thread *td) 939{ 940 struct shmfd *shmfd; 941 int error; 942 943 error = 0; 944 shmfd = fp->f_data; 945 mtx_lock(&shm_timestamp_lock); 946#ifdef MAC 947 error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid); 948 if (error != 0) 949 goto out; 950#endif 951 if (uid == (uid_t)-1) 952 uid = shmfd->shm_uid; 953 if (gid == (gid_t)-1) 954 gid = shmfd->shm_gid; 955 if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) || 956 (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) && 957 (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0))) 958 goto out; 959 shmfd->shm_uid = uid; 960 shmfd->shm_gid = gid; 961out: 962 mtx_unlock(&shm_timestamp_lock); 963 return (error); 964} 965 966/* 967 * Helper routines to allow the backing object of a shared memory file 968 * descriptor to be mapped in the kernel. 969 */ 970int 971shm_map(struct file *fp, size_t size, off_t offset, void **memp) 972{ 973 struct shmfd *shmfd; 974 vm_offset_t kva, ofs; 975 vm_object_t obj; 976 int rv; 977 978 if (fp->f_type != DTYPE_SHM) 979 return (EINVAL); 980 shmfd = fp->f_data; 981 obj = shmfd->shm_object; 982 VM_OBJECT_WLOCK(obj); 983 /* 984 * XXXRW: This validation is probably insufficient, and subject to 985 * sign errors. It should be fixed. 986 */ 987 if (offset >= shmfd->shm_size || 988 offset + size > round_page(shmfd->shm_size)) { 989 VM_OBJECT_WUNLOCK(obj); 990 return (EINVAL); 991 } 992 993 shmfd->shm_kmappings++; 994 vm_object_reference_locked(obj); 995 VM_OBJECT_WUNLOCK(obj); 996 997 /* Map the object into the kernel_map and wire it. */ 998 kva = vm_map_min(kernel_map); 999 ofs = offset & PAGE_MASK; 1000 offset = trunc_page(offset); 1001 size = round_page(size + ofs); 1002 rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0, 1003 VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE, 1004 VM_PROT_READ | VM_PROT_WRITE, 0); 1005 if (rv == KERN_SUCCESS) { 1006 rv = vm_map_wire(kernel_map, kva, kva + size, 1007 VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES); 1008 if (rv == KERN_SUCCESS) { 1009 *memp = (void *)(kva + ofs); 1010 return (0); 1011 } 1012 vm_map_remove(kernel_map, kva, kva + size); 1013 } else 1014 vm_object_deallocate(obj); 1015 1016 /* On failure, drop our mapping reference. */ 1017 VM_OBJECT_WLOCK(obj); 1018 shmfd->shm_kmappings--; 1019 VM_OBJECT_WUNLOCK(obj); 1020 1021 return (vm_mmap_to_errno(rv)); 1022} 1023 1024/* 1025 * We require the caller to unmap the entire entry. This allows us to 1026 * safely decrement shm_kmappings when a mapping is removed. 1027 */ 1028int 1029shm_unmap(struct file *fp, void *mem, size_t size) 1030{ 1031 struct shmfd *shmfd; 1032 vm_map_entry_t entry; 1033 vm_offset_t kva, ofs; 1034 vm_object_t obj; 1035 vm_pindex_t pindex; 1036 vm_prot_t prot; 1037 boolean_t wired; 1038 vm_map_t map; 1039 int rv; 1040 1041 if (fp->f_type != DTYPE_SHM) 1042 return (EINVAL); 1043 shmfd = fp->f_data; 1044 kva = (vm_offset_t)mem; 1045 ofs = kva & PAGE_MASK; 1046 kva = trunc_page(kva); 1047 size = round_page(size + ofs); 1048 map = kernel_map; 1049 rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry, 1050 &obj, &pindex, &prot, &wired); 1051 if (rv != KERN_SUCCESS) 1052 return (EINVAL); 1053 if (entry->start != kva || entry->end != kva + size) { 1054 vm_map_lookup_done(map, entry); 1055 return (EINVAL); 1056 } 1057 vm_map_lookup_done(map, entry); 1058 if (obj != shmfd->shm_object) 1059 return (EINVAL); 1060 vm_map_remove(map, kva, kva + size); 1061 VM_OBJECT_WLOCK(obj); 1062 KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); 1063 shmfd->shm_kmappings--; 1064 VM_OBJECT_WUNLOCK(obj); 1065 return (0); 1066} 1067 1068void 1069shm_path(struct shmfd *shmfd, char *path, size_t size) 1070{ 1071 const char *shm_path, *pr_path; 1072 size_t pr_pathlen; 1073 1074 if (shmfd->shm_path == NULL) 1075 return; 1076 sx_slock(&shm_dict_lock); 1077 shm_path = shmfd->shm_path; 1078 if (shm_path != NULL) { 1079 pr_path = curthread->td_ucred->cr_prison->pr_path; 1080 if (strcmp(pr_path, "/") != 0) { 1081 /* Return the jail-rooted pathname. */ 1082 pr_pathlen = strlen(pr_path); 1083 if (strncmp(shm_path, pr_path, pr_pathlen) == 0 && 1084 shm_path[pr_pathlen] == '/') 1085 shm_path += pr_pathlen; 1086 } 1087 strlcpy(path, shm_path, size); 1088 } 1089 sx_sunlock(&shm_dict_lock); 1090} 1091