sys/kern/uipc_shm.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2006, 2011, 2016-2017 Robert N. M. Watson
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed by BAE Systems, the University of
   8  * Cambridge Computer Laboratory, and Memorial University under DARPA/AFRL
   9  * contract FA8650-15-C-7558 ("CADETS"), as part of the DARPA Transparent
  10  * Computing (TC) research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Support for shared swap-backed anonymous memory objects via
  36  * shm_open(2) and shm_unlink(2).  While most of the implementation is
  37  * here, vm_mmap.c contains mapping logic changes.
  38  *
  39  * posixshmcontrol(1) allows users to inspect the state of the memory
  40  * objects.  Per-uid swap resource limit controls total amount of
  41  * memory that user can consume for anonymous objects, including
  42  * shared.
  43  */
  44
  45 #include <sys/cdefs.h>
  46 __FBSDID("$FreeBSD$");
  47
  48 #include "opt_capsicum.h"
  49 #include "opt_ktrace.h"
  50
  51 #include <sys/param.h>
  52 #include <sys/capsicum.h>
  53 #include <sys/conf.h>
  54 #include <sys/fcntl.h>
  55 #include <sys/file.h>
  56 #include <sys/filedesc.h>
  57 #include <sys/filio.h>
  58 #include <sys/fnv_hash.h>
  59 #include <sys/kernel.h>
  60 #include <sys/uio.h>
  61 #include <sys/signal.h>
  62 #include <sys/jail.h>
  63 #include <sys/ktrace.h>
  64 #include <sys/lock.h>
  65 #include <sys/malloc.h>
  66 #include <sys/mman.h>
  67 #include <sys/mutex.h>
  68 #include <sys/priv.h>
  69 #include <sys/proc.h>
  70 #include <sys/refcount.h>
  71 #include <sys/resourcevar.h>
  72 #include <sys/rwlock.h>
  73 #include <sys/sbuf.h>
  74 #include <sys/stat.h>
  75 #include <sys/syscallsubr.h>
  76 #include <sys/sysctl.h>
  77 #include <sys/sysproto.h>
  78 #include <sys/systm.h>
  79 #include <sys/sx.h>
  80 #include <sys/time.h>
  81 #include <sys/vnode.h>
  82 #include <sys/unistd.h>
  83 #include <sys/user.h>
  84
  85 #include <security/audit/audit.h>
  86 #include <security/mac/mac_framework.h>
  87
  88 #include <vm/vm.h>
  89 #include <vm/vm_param.h>
  90 #include <vm/pmap.h>
  91 #include <vm/vm_extern.h>
  92 #include <vm/vm_map.h>
  93 #include <vm/vm_kern.h>
  94 #include <vm/vm_object.h>
  95 #include <vm/vm_page.h>
  96 #include <vm/vm_pageout.h>
  97 #include <vm/vm_pager.h>
  98 #include <vm/swap_pager.h>
  99
 100 struct shm_mapping {
 101         char            *sm_path;
 102         Fnv32_t         sm_fnv;
 103         struct shmfd    *sm_shmfd;
 104         LIST_ENTRY(shm_mapping) sm_link;
 105 };
 106
 107 static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
 108 static LIST_HEAD(, shm_mapping) *shm_dictionary;
 109 static struct sx shm_dict_lock;
 110 static struct mtx shm_timestamp_lock;
 111 static u_long shm_hash;
 112 static struct unrhdr64 shm_ino_unr;
 113 static dev_t shm_dev_ino;
 114
 115 #define SHM_HASH(fnv)   (&shm_dictionary[(fnv) & shm_hash])
 116
 117 static void     shm_init(void *arg);
 118 static void     shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
 119 static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
 120 static int      shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
 121
 122 static fo_rdwr_t        shm_read;
 123 static fo_rdwr_t        shm_write;
 124 static fo_truncate_t    shm_truncate;
 125 static fo_ioctl_t       shm_ioctl;
 126 static fo_stat_t        shm_stat;
 127 static fo_close_t       shm_close;
 128 static fo_chmod_t       shm_chmod;
 129 static fo_chown_t       shm_chown;
 130 static fo_seek_t        shm_seek;
 131 static fo_fill_kinfo_t  shm_fill_kinfo;
 132 static fo_mmap_t        shm_mmap;
 133
 134 /* File descriptor operations. */
 135 struct fileops shm_ops = {
 136         .fo_read = shm_read,
 137         .fo_write = shm_write,
 138         .fo_truncate = shm_truncate,
 139         .fo_ioctl = shm_ioctl,
 140         .fo_poll = invfo_poll,
 141         .fo_kqfilter = invfo_kqfilter,
 142         .fo_stat = shm_stat,
 143         .fo_close = shm_close,
 144         .fo_chmod = shm_chmod,
 145         .fo_chown = shm_chown,
 146         .fo_sendfile = vn_sendfile,
 147         .fo_seek = shm_seek,
 148         .fo_fill_kinfo = shm_fill_kinfo,
 149         .fo_mmap = shm_mmap,
 150         .fo_flags = DFLAG_PASSABLE | DFLAG_SEEKABLE
 151 };
 152
 153 FEATURE(posix_shm, "POSIX shared memory");
 154
 155 static int
 156 uiomove_object_page(vm_object_t obj, size_t len, struct uio *uio)
 157 {
 158         vm_page_t m;
 159         vm_pindex_t idx;
 160         size_t tlen;
 161         int error, offset, rv;
 162
 163         idx = OFF_TO_IDX(uio->uio_offset);
 164         offset = uio->uio_offset & PAGE_MASK;
 165         tlen = MIN(PAGE_SIZE - offset, len);
 166
 167         VM_OBJECT_WLOCK(obj);
 168
 169         /*
 170          * Read I/O without either a corresponding resident page or swap
 171          * page: use zero_region.  This is intended to avoid instantiating
 172          * pages on read from a sparse region.
 173          */
 174         if (uio->uio_rw == UIO_READ && vm_page_lookup(obj, idx) == NULL &&
 175             !vm_pager_has_page(obj, idx, NULL, NULL)) {
 176                 VM_OBJECT_WUNLOCK(obj);
 177                 return (uiomove(__DECONST(void *, zero_region), tlen, uio));
 178         }
 179
 180         /*
 181          * Parallel reads of the page content from disk are prevented
 182          * by exclusive busy.
 183          *
 184          * Although the tmpfs vnode lock is held here, it is
 185          * nonetheless safe to sleep waiting for a free page.  The
 186          * pageout daemon does not need to acquire the tmpfs vnode
 187          * lock to page out tobj's pages because tobj is a OBJT_SWAP
 188          * type object.
 189          */
 190         m = vm_page_grab(obj, idx, VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY);
 191         if (m->valid != VM_PAGE_BITS_ALL) {
 192                 vm_page_xbusy(m);
 193                 if (vm_pager_has_page(obj, idx, NULL, NULL)) {
 194                         rv = vm_pager_get_pages(obj, &m, 1, NULL, NULL);
 195                         if (rv != VM_PAGER_OK) {
 196                                 printf(
 197             "uiomove_object: vm_obj %p idx %jd valid %x pager error %d\n",
 198                                     obj, idx, m->valid, rv);
 199                                 vm_page_lock(m);
 200                                 vm_page_free(m);
 201                                 vm_page_unlock(m);
 202                                 VM_OBJECT_WUNLOCK(obj);
 203                                 return (EIO);
 204                         }
 205                 } else
 206                         vm_page_zero_invalid(m, TRUE);
 207                 vm_page_xunbusy(m);
 208         }
 209         vm_page_lock(m);
 210         vm_page_wire(m);
 211         vm_page_unlock(m);
 212         VM_OBJECT_WUNLOCK(obj);
 213         error = uiomove_fromphys(&m, offset, tlen, uio);
 214         if (uio->uio_rw == UIO_WRITE && error == 0) {
 215                 VM_OBJECT_WLOCK(obj);
 216                 vm_page_dirty(m);
 217                 vm_pager_page_unswapped(m);
 218                 VM_OBJECT_WUNLOCK(obj);
 219         }
 220         vm_page_lock(m);
 221         vm_page_unwire(m, PQ_ACTIVE);
 222         vm_page_unlock(m);
 223
 224         return (error);
 225 }
 226
 227 int
 228 uiomove_object(vm_object_t obj, off_t obj_size, struct uio *uio)
 229 {
 230         ssize_t resid;
 231         size_t len;
 232         int error;
 233
 234         error = 0;
 235         while ((resid = uio->uio_resid) > 0) {
 236                 if (obj_size <= uio->uio_offset)
 237                         break;
 238                 len = MIN(obj_size - uio->uio_offset, resid);
 239                 if (len == 0)
 240                         break;
 241                 error = uiomove_object_page(obj, len, uio);
 242                 if (error != 0 || resid == uio->uio_resid)
 243                         break;
 244         }
 245         return (error);
 246 }
 247
 248 static int
 249 shm_seek(struct file *fp, off_t offset, int whence, struct thread *td)
 250 {
 251         struct shmfd *shmfd;
 252         off_t foffset;
 253         int error;
 254
 255         shmfd = fp->f_data;
 256         foffset = foffset_lock(fp, 0);
 257         error = 0;
 258         switch (whence) {
 259         case L_INCR:
 260                 if (foffset < 0 ||
 261                     (offset > 0 && foffset > OFF_MAX - offset)) {
 262                         error = EOVERFLOW;
 263                         break;
 264                 }
 265                 offset += foffset;
 266                 break;
 267         case L_XTND:
 268                 if (offset > 0 && shmfd->shm_size > OFF_MAX - offset) {
 269                         error = EOVERFLOW;
 270                         break;
 271                 }
 272                 offset += shmfd->shm_size;
 273                 break;
 274         case L_SET:
 275                 break;
 276         default:
 277                 error = EINVAL;
 278         }
 279         if (error == 0) {
 280                 if (offset < 0 || offset > shmfd->shm_size)
 281                         error = EINVAL;
 282                 else
 283                         td->td_uretoff.tdu_off = offset;
 284         }
 285         foffset_unlock(fp, offset, error != 0 ? FOF_NOUPDATE : 0);
 286         return (error);
 287 }
 288
 289 static int
 290 shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
 291     int flags, struct thread *td)
 292 {
 293         struct shmfd *shmfd;
 294         void *rl_cookie;
 295         int error;
 296
 297         shmfd = fp->f_data;
 298 #ifdef MAC
 299         error = mac_posixshm_check_read(active_cred, fp->f_cred, shmfd);
 300         if (error)
 301                 return (error);
 302 #endif
 303         foffset_lock_uio(fp, uio, flags);
 304         rl_cookie = rangelock_rlock(&shmfd->shm_rl, uio->uio_offset,
 305             uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
 306         error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
 307         rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
 308         foffset_unlock_uio(fp, uio, flags);
 309         return (error);
 310 }
 311
 312 static int
 313 shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
 314     int flags, struct thread *td)
 315 {
 316         struct shmfd *shmfd;
 317         void *rl_cookie;
 318         int error;
 319
 320         shmfd = fp->f_data;
 321 #ifdef MAC
 322         error = mac_posixshm_check_write(active_cred, fp->f_cred, shmfd);
 323         if (error)
 324                 return (error);
 325 #endif
 326         foffset_lock_uio(fp, uio, flags);
 327         if ((flags & FOF_OFFSET) == 0) {
 328                 rl_cookie = rangelock_wlock(&shmfd->shm_rl, 0, OFF_MAX,
 329                     &shmfd->shm_mtx);
 330         } else {
 331                 rl_cookie = rangelock_wlock(&shmfd->shm_rl, uio->uio_offset,
 332                     uio->uio_offset + uio->uio_resid, &shmfd->shm_mtx);
 333         }
 334
 335         error = uiomove_object(shmfd->shm_object, shmfd->shm_size, uio);
 336         rangelock_unlock(&shmfd->shm_rl, rl_cookie, &shmfd->shm_mtx);
 337         foffset_unlock_uio(fp, uio, flags);
 338         return (error);
 339 }
 340
 341 static int
 342 shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
 343     struct thread *td)
 344 {
 345         struct shmfd *shmfd;
 346 #ifdef MAC
 347         int error;
 348 #endif
 349
 350         shmfd = fp->f_data;
 351 #ifdef MAC
 352         error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
 353         if (error)
 354                 return (error);
 355 #endif
 356         return (shm_dotruncate(shmfd, length));
 357 }
 358
 359 int
 360 shm_ioctl(struct file *fp, u_long com, void *data, struct ucred *active_cred,
 361     struct thread *td)
 362 {
 363
 364         switch (com) {
 365         case FIONBIO:
 366         case FIOASYNC:
 367                 /*
 368                  * Allow fcntl(fd, F_SETFL, O_NONBLOCK) to work,
 369                  * just like it would on an unlinked regular file
 370                  */
 371                 return (0);
 372         default:
 373                 return (ENOTTY);
 374         }
 375 }
 376
 377 static int
 378 shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
 379     struct thread *td)
 380 {
 381         struct shmfd *shmfd;
 382 #ifdef MAC
 383         int error;
 384 #endif
 385
 386         shmfd = fp->f_data;
 387
 388 #ifdef MAC
 389         error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
 390         if (error)
 391                 return (error);
 392 #endif
 393
 394         /*
 395          * Attempt to return sanish values for fstat() on a memory file
 396          * descriptor.
 397          */
 398         bzero(sb, sizeof(*sb));
 399         sb->st_blksize = PAGE_SIZE;
 400         sb->st_size = shmfd->shm_size;
 401         sb->st_blocks = howmany(sb->st_size, sb->st_blksize);
 402         mtx_lock(&shm_timestamp_lock);
 403         sb->st_atim = shmfd->shm_atime;
 404         sb->st_ctim = shmfd->shm_ctime;
 405         sb->st_mtim = shmfd->shm_mtime;
 406         sb->st_birthtim = shmfd->shm_birthtime;
 407         sb->st_mode = S_IFREG | shmfd->shm_mode;                /* XXX */
 408         sb->st_uid = shmfd->shm_uid;
 409         sb->st_gid = shmfd->shm_gid;
 410         mtx_unlock(&shm_timestamp_lock);
 411         sb->st_dev = shm_dev_ino;
 412         sb->st_ino = shmfd->shm_ino;
 413         sb->st_nlink = shmfd->shm_object->ref_count;
 414
 415         return (0);
 416 }
 417
 418 static int
 419 shm_close(struct file *fp, struct thread *td)
 420 {
 421         struct shmfd *shmfd;
 422
 423         shmfd = fp->f_data;
 424         fp->f_data = NULL;
 425         shm_drop(shmfd);
 426
 427         return (0);
 428 }
 429
 430 int
 431 shm_dotruncate(struct shmfd *shmfd, off_t length)
 432 {
 433         vm_object_t object;
 434         vm_page_t m;
 435         vm_pindex_t idx, nobjsize;
 436         vm_ooffset_t delta;
 437         int base, rv;
 438
 439         KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
 440         object = shmfd->shm_object;
 441         VM_OBJECT_WLOCK(object);
 442         if (length == shmfd->shm_size) {
 443                 VM_OBJECT_WUNLOCK(object);
 444                 return (0);
 445         }
 446         nobjsize = OFF_TO_IDX(length + PAGE_MASK);
 447
 448         /* Are we shrinking?  If so, trim the end. */
 449         if (length < shmfd->shm_size) {
 450                 /*
 451                  * Disallow any requests to shrink the size if this
 452                  * object is mapped into the kernel.
 453                  */
 454                 if (shmfd->shm_kmappings > 0) {
 455                         VM_OBJECT_WUNLOCK(object);
 456                         return (EBUSY);
 457                 }
 458
 459                 /*
 460                  * Zero the truncated part of the last page.
 461                  */
 462                 base = length & PAGE_MASK;
 463                 if (base != 0) {
 464                         idx = OFF_TO_IDX(length);
 465 retry:
 466                         m = vm_page_lookup(object, idx);
 467                         if (m != NULL) {
 468                                 if (vm_page_sleep_if_busy(m, "shmtrc"))
 469                                         goto retry;
 470                         } else if (vm_pager_has_page(object, idx, NULL, NULL)) {
 471                                 m = vm_page_alloc(object, idx,
 472                                     VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL);
 473                                 if (m == NULL)
 474                                         goto retry;
 475                                 rv = vm_pager_get_pages(object, &m, 1, NULL,
 476                                     NULL);
 477                                 vm_page_lock(m);
 478                                 if (rv == VM_PAGER_OK) {
 479                                         /*
 480                                          * Since the page was not resident,
 481                                          * and therefore not recently
 482                                          * accessed, immediately enqueue it
 483                                          * for asynchronous laundering.  The
 484                                          * current operation is not regarded
 485                                          * as an access.
 486                                          */
 487                                         vm_page_launder(m);
 488                                         vm_page_unlock(m);
 489                                         vm_page_xunbusy(m);
 490                                 } else {
 491                                         vm_page_free(m);
 492                                         vm_page_unlock(m);
 493                                         VM_OBJECT_WUNLOCK(object);
 494                                         return (EIO);
 495                                 }
 496                         }
 497                         if (m != NULL) {
 498                                 pmap_zero_page_area(m, base, PAGE_SIZE - base);
 499                                 KASSERT(m->valid == VM_PAGE_BITS_ALL,
 500                                     ("shm_dotruncate: page %p is invalid", m));
 501                                 vm_page_dirty(m);
 502                                 vm_pager_page_unswapped(m);
 503                         }
 504                 }
 505                 delta = IDX_TO_OFF(object->size - nobjsize);
 506
 507                 /* Toss in memory pages. */
 508                 if (nobjsize < object->size)
 509                         vm_object_page_remove(object, nobjsize, object->size,
 510                             0);
 511
 512                 /* Toss pages from swap. */
 513                 if (object->type == OBJT_SWAP)
 514                         swap_pager_freespace(object, nobjsize, delta);
 515
 516                 /* Free the swap accounted for shm */
 517                 swap_release_by_cred(delta, object->cred);
 518                 object->charge -= delta;
 519         } else {
 520                 /* Try to reserve additional swap space. */
 521                 delta = IDX_TO_OFF(nobjsize - object->size);
 522                 if (!swap_reserve_by_cred(delta, object->cred)) {
 523                         VM_OBJECT_WUNLOCK(object);
 524                         return (ENOMEM);
 525                 }
 526                 object->charge += delta;
 527         }
 528         shmfd->shm_size = length;
 529         mtx_lock(&shm_timestamp_lock);
 530         vfs_timestamp(&shmfd->shm_ctime);
 531         shmfd->shm_mtime = shmfd->shm_ctime;
 532         mtx_unlock(&shm_timestamp_lock);
 533         object->size = nobjsize;
 534         VM_OBJECT_WUNLOCK(object);
 535         return (0);
 536 }
 537
 538 /*
 539  * shmfd object management including creation and reference counting
 540  * routines.
 541  */
 542 struct shmfd *
 543 shm_alloc(struct ucred *ucred, mode_t mode)
 544 {
 545         struct shmfd *shmfd;
 546
 547         shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
 548         shmfd->shm_size = 0;
 549         shmfd->shm_uid = ucred->cr_uid;
 550         shmfd->shm_gid = ucred->cr_gid;
 551         shmfd->shm_mode = mode;
 552         shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
 553             shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
 554         KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
 555         shmfd->shm_object->pg_color = 0;
 556         VM_OBJECT_WLOCK(shmfd->shm_object);
 557         vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
 558         vm_object_set_flag(shmfd->shm_object, OBJ_COLORED | OBJ_NOSPLIT);
 559         VM_OBJECT_WUNLOCK(shmfd->shm_object);
 560         vfs_timestamp(&shmfd->shm_birthtime);
 561         shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
 562             shmfd->shm_birthtime;
 563         shmfd->shm_ino = alloc_unr64(&shm_ino_unr);
 564         refcount_init(&shmfd->shm_refs, 1);
 565         mtx_init(&shmfd->shm_mtx, "shmrl", NULL, MTX_DEF);
 566         rangelock_init(&shmfd->shm_rl);
 567 #ifdef MAC
 568         mac_posixshm_init(shmfd);
 569         mac_posixshm_create(ucred, shmfd);
 570 #endif
 571
 572         return (shmfd);
 573 }
 574
 575 struct shmfd *
 576 shm_hold(struct shmfd *shmfd)
 577 {
 578
 579         refcount_acquire(&shmfd->shm_refs);
 580         return (shmfd);
 581 }
 582
 583 void
 584 shm_drop(struct shmfd *shmfd)
 585 {
 586
 587         if (refcount_release(&shmfd->shm_refs)) {
 588 #ifdef MAC
 589                 mac_posixshm_destroy(shmfd);
 590 #endif
 591                 rangelock_destroy(&shmfd->shm_rl);
 592                 mtx_destroy(&shmfd->shm_mtx);
 593                 vm_object_deallocate(shmfd->shm_object);
 594                 free(shmfd, M_SHMFD);
 595         }
 596 }
 597
 598 /*
 599  * Determine if the credentials have sufficient permissions for a
 600  * specified combination of FREAD and FWRITE.
 601  */
 602 int
 603 shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
 604 {
 605         accmode_t accmode;
 606         int error;
 607
 608         accmode = 0;
 609         if (flags & FREAD)
 610                 accmode |= VREAD;
 611         if (flags & FWRITE)
 612                 accmode |= VWRITE;
 613         mtx_lock(&shm_timestamp_lock);
 614         error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
 615             accmode, ucred, NULL);
 616         mtx_unlock(&shm_timestamp_lock);
 617         return (error);
 618 }
 619
 620 /*
 621  * Dictionary management.  We maintain an in-kernel dictionary to map
 622  * paths to shmfd objects.  We use the FNV hash on the path to store
 623  * the mappings in a hash table.
 624  */
 625 static void
 626 shm_init(void *arg)
 627 {
 628
 629         mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
 630         sx_init(&shm_dict_lock, "shm dictionary");
 631         shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
 632         new_unrhdr64(&shm_ino_unr, 1);
 633         shm_dev_ino = devfs_alloc_cdp_inode();
 634         KASSERT(shm_dev_ino > 0, ("shm dev inode not initialized"));
 635 }
 636 SYSINIT(shm_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_init, NULL);
 637
 638 static struct shmfd *
 639 shm_lookup(char *path, Fnv32_t fnv)
 640 {
 641         struct shm_mapping *map;
 642
 643         LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
 644                 if (map->sm_fnv != fnv)
 645                         continue;
 646                 if (strcmp(map->sm_path, path) == 0)
 647                         return (map->sm_shmfd);
 648         }
 649
 650         return (NULL);
 651 }
 652
 653 static void
 654 shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
 655 {
 656         struct shm_mapping *map;
 657
 658         map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
 659         map->sm_path = path;
 660         map->sm_fnv = fnv;
 661         map->sm_shmfd = shm_hold(shmfd);
 662         shmfd->shm_path = path;
 663         LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
 664 }
 665
 666 static int
 667 shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
 668 {
 669         struct shm_mapping *map;
 670         int error;
 671
 672         LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
 673                 if (map->sm_fnv != fnv)
 674                         continue;
 675                 if (strcmp(map->sm_path, path) == 0) {
 676 #ifdef MAC
 677                         error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
 678                         if (error)
 679                                 return (error);
 680 #endif
 681                         error = shm_access(map->sm_shmfd, ucred,
 682                             FREAD | FWRITE);
 683                         if (error)
 684                                 return (error);
 685                         map->sm_shmfd->shm_path = NULL;
 686                         LIST_REMOVE(map, sm_link);
 687                         shm_drop(map->sm_shmfd);
 688                         free(map->sm_path, M_SHMFD);
 689                         free(map, M_SHMFD);
 690                         return (0);
 691                 }
 692         }
 693
 694         return (ENOENT);
 695 }
 696
 697 int
 698 kern_shm_open(struct thread *td, const char *userpath, int flags, mode_t mode,
 699     struct filecaps *fcaps)
 700 {
 701         struct filedesc *fdp;
 702         struct shmfd *shmfd;
 703         struct file *fp;
 704         char *path;
 705         const char *pr_path;
 706         size_t pr_pathlen;
 707         Fnv32_t fnv;
 708         mode_t cmode;
 709         int fd, error;
 710
 711 #ifdef CAPABILITY_MODE
 712         /*
 713          * shm_open(2) is only allowed for anonymous objects.
 714          */
 715         if (IN_CAPABILITY_MODE(td) && (userpath != SHM_ANON))
 716                 return (ECAPMODE);
 717 #endif
 718
 719         AUDIT_ARG_FFLAGS(flags);
 720         AUDIT_ARG_MODE(mode);
 721
 722         if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR)
 723                 return (EINVAL);
 724
 725         if ((flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC | O_CLOEXEC)) != 0)
 726                 return (EINVAL);
 727
 728         fdp = td->td_proc->p_fd;
 729         cmode = (mode & ~fdp->fd_cmask) & ACCESSPERMS;
 730
 731         error = falloc_caps(td, &fp, &fd, O_CLOEXEC, fcaps);
 732         if (error)
 733                 return (error);
 734
 735         /* A SHM_ANON path pointer creates an anonymous object. */
 736         if (userpath == SHM_ANON) {
 737                 /* A read-only anonymous object is pointless. */
 738                 if ((flags & O_ACCMODE) == O_RDONLY) {
 739                         fdclose(td, fp, fd);
 740                         fdrop(fp, td);
 741                         return (EINVAL);
 742                 }
 743                 shmfd = shm_alloc(td->td_ucred, cmode);
 744         } else {
 745                 path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
 746                 pr_path = td->td_ucred->cr_prison->pr_path;
 747
 748                 /* Construct a full pathname for jailed callers. */
 749                 pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
 750                     : strlcpy(path, pr_path, MAXPATHLEN);
 751                 error = copyinstr(userpath, path + pr_pathlen,
 752                     MAXPATHLEN - pr_pathlen, NULL);
 753 #ifdef KTRACE
 754                 if (error == 0 && KTRPOINT(curthread, KTR_NAMEI))
 755                         ktrnamei(path);
 756 #endif
 757                 /* Require paths to start with a '/' character. */
 758                 if (error == 0 && path[pr_pathlen] != '/')
 759                         error = EINVAL;
 760                 if (error) {
 761                         fdclose(td, fp, fd);
 762                         fdrop(fp, td);
 763                         free(path, M_SHMFD);
 764                         return (error);
 765                 }
 766
 767                 AUDIT_ARG_UPATH1_CANON(path);
 768                 fnv = fnv_32_str(path, FNV1_32_INIT);
 769                 sx_xlock(&shm_dict_lock);
 770                 shmfd = shm_lookup(path, fnv);
 771                 if (shmfd == NULL) {
 772                         /* Object does not yet exist, create it if requested. */
 773                         if (flags & O_CREAT) {
 774 #ifdef MAC
 775                                 error = mac_posixshm_check_create(td->td_ucred,
 776                                     path);
 777                                 if (error == 0) {
 778 #endif
 779                                         shmfd = shm_alloc(td->td_ucred, cmode);
 780                                         shm_insert(path, fnv, shmfd);
 781 #ifdef MAC
 782                                 }
 783 #endif
 784                         } else {
 785                                 free(path, M_SHMFD);
 786                                 error = ENOENT;
 787                         }
 788                 } else {
 789                         /*
 790                          * Object already exists, obtain a new
 791                          * reference if requested and permitted.
 792                          */
 793                         free(path, M_SHMFD);
 794                         if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
 795                                 error = EEXIST;
 796                         else {
 797 #ifdef MAC
 798                                 error = mac_posixshm_check_open(td->td_ucred,
 799                                     shmfd, FFLAGS(flags & O_ACCMODE));
 800                                 if (error == 0)
 801 #endif
 802                                 error = shm_access(shmfd, td->td_ucred,
 803                                     FFLAGS(flags & O_ACCMODE));
 804                         }
 805
 806                         /*
 807                          * Truncate the file back to zero length if
 808                          * O_TRUNC was specified and the object was
 809                          * opened with read/write.
 810                          */
 811                         if (error == 0 &&
 812                             (flags & (O_ACCMODE | O_TRUNC)) ==
 813                             (O_RDWR | O_TRUNC)) {
 814 #ifdef MAC
 815                                 error = mac_posixshm_check_truncate(
 816                                         td->td_ucred, fp->f_cred, shmfd);
 817                                 if (error == 0)
 818 #endif
 819                                         shm_dotruncate(shmfd, 0);
 820                         }
 821                         if (error == 0)
 822                                 shm_hold(shmfd);
 823                 }
 824                 sx_xunlock(&shm_dict_lock);
 825
 826                 if (error) {
 827                         fdclose(td, fp, fd);
 828                         fdrop(fp, td);
 829                         return (error);
 830                 }
 831         }
 832
 833         finit(fp, FFLAGS(flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
 834
 835         td->td_retval[0] = fd;
 836         fdrop(fp, td);
 837
 838         return (0);
 839 }
 840
 841 /* System calls. */
 842 int
 843 sys_shm_open(struct thread *td, struct shm_open_args *uap)
 844 {
 845
 846         return (kern_shm_open(td, uap->path, uap->flags, uap->mode, NULL));
 847 }
 848
 849 int
 850 sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
 851 {
 852         char *path;
 853         const char *pr_path;
 854         size_t pr_pathlen;
 855         Fnv32_t fnv;
 856         int error;
 857
 858         path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
 859         pr_path = td->td_ucred->cr_prison->pr_path;
 860         pr_pathlen = strcmp(pr_path, "/") == 0 ? 0
 861             : strlcpy(path, pr_path, MAXPATHLEN);
 862         error = copyinstr(uap->path, path + pr_pathlen, MAXPATHLEN - pr_pathlen,
 863             NULL);
 864         if (error) {
 865                 free(path, M_TEMP);
 866                 return (error);
 867         }
 868 #ifdef KTRACE
 869         if (KTRPOINT(curthread, KTR_NAMEI))
 870                 ktrnamei(path);
 871 #endif
 872         AUDIT_ARG_UPATH1_CANON(path);
 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 int
 883 shm_mmap(struct file *fp, vm_map_t map, vm_offset_t *addr, vm_size_t objsize,
 884     vm_prot_t prot, vm_prot_t cap_maxprot, int flags,
 885     vm_ooffset_t foff, struct thread *td)
 886 {
 887         struct shmfd *shmfd;
 888         vm_prot_t maxprot;
 889         int error;
 890
 891         shmfd = fp->f_data;
 892         maxprot = VM_PROT_NONE;
 893
 894         /* FREAD should always be set. */
 895         if ((fp->f_flag & FREAD) != 0)
 896                 maxprot |= VM_PROT_EXECUTE | VM_PROT_READ;
 897         if ((fp->f_flag & FWRITE) != 0)
 898                 maxprot |= VM_PROT_WRITE;
 899
 900         /* Don't permit shared writable mappings on read-only descriptors. */
 901         if ((flags & MAP_SHARED) != 0 &&
 902             (maxprot & VM_PROT_WRITE) == 0 &&
 903             (prot & VM_PROT_WRITE) != 0)
 904                 return (EACCES);
 905         maxprot &= cap_maxprot;
 906
 907         /* See comment in vn_mmap(). */
 908         if (
 909 #ifdef _LP64
 910             objsize > OFF_MAX ||
 911 #endif
 912             foff < 0 || foff > OFF_MAX - objsize)
 913                 return (EINVAL);
 914
 915 #ifdef MAC
 916         error = mac_posixshm_check_mmap(td->td_ucred, shmfd, prot, flags);
 917         if (error != 0)
 918                 return (error);
 919 #endif
 920
 921         mtx_lock(&shm_timestamp_lock);
 922         vfs_timestamp(&shmfd->shm_atime);
 923         mtx_unlock(&shm_timestamp_lock);
 924         vm_object_reference(shmfd->shm_object);
 925
 926         error = vm_mmap_object(map, addr, objsize, prot, maxprot, flags,
 927             shmfd->shm_object, foff, FALSE, td);
 928         if (error != 0)
 929                 vm_object_deallocate(shmfd->shm_object);
 930         return (error);
 931 }
 932
 933 static int
 934 shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
 935     struct thread *td)
 936 {
 937         struct shmfd *shmfd;
 938         int error;
 939
 940         error = 0;
 941         shmfd = fp->f_data;
 942         mtx_lock(&shm_timestamp_lock);
 943         /*
 944          * SUSv4 says that x bits of permission need not be affected.
 945          * Be consistent with our shm_open there.
 946          */
 947 #ifdef MAC
 948         error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
 949         if (error != 0)
 950                 goto out;
 951 #endif
 952         error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
 953             shmfd->shm_gid, VADMIN, active_cred, NULL);
 954         if (error != 0)
 955                 goto out;
 956         shmfd->shm_mode = mode & ACCESSPERMS;
 957 out:
 958         mtx_unlock(&shm_timestamp_lock);
 959         return (error);
 960 }
 961
 962 static int
 963 shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
 964     struct thread *td)
 965 {
 966         struct shmfd *shmfd;
 967         int error;
 968
 969         error = 0;
 970         shmfd = fp->f_data;
 971         mtx_lock(&shm_timestamp_lock);
 972 #ifdef MAC
 973         error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
 974         if (error != 0)
 975                 goto out;
 976 #endif
 977         if (uid == (uid_t)-1)
 978                 uid = shmfd->shm_uid;
 979         if (gid == (gid_t)-1)
 980                  gid = shmfd->shm_gid;
 981         if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
 982             (gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
 983             (error = priv_check_cred(active_cred, PRIV_VFS_CHOWN)))
 984                 goto out;
 985         shmfd->shm_uid = uid;
 986         shmfd->shm_gid = gid;
 987 out:
 988         mtx_unlock(&shm_timestamp_lock);
 989         return (error);
 990 }
 991
 992 /*
 993  * Helper routines to allow the backing object of a shared memory file
 994  * descriptor to be mapped in the kernel.
 995  */
 996 int
 997 shm_map(struct file *fp, size_t size, off_t offset, void **memp)
 998 {
 999         struct shmfd *shmfd;
1000         vm_offset_t kva, ofs;
1001         vm_object_t obj;
1002         int rv;
1003
1004         if (fp->f_type != DTYPE_SHM)
1005                 return (EINVAL);
1006         shmfd = fp->f_data;
1007         obj = shmfd->shm_object;
1008         VM_OBJECT_WLOCK(obj);
1009         /*
1010          * XXXRW: This validation is probably insufficient, and subject to
1011          * sign errors.  It should be fixed.
1012          */
1013         if (offset >= shmfd->shm_size ||
1014             offset + size > round_page(shmfd->shm_size)) {
1015                 VM_OBJECT_WUNLOCK(obj);
1016                 return (EINVAL);
1017         }
1018
1019         shmfd->shm_kmappings++;
1020         vm_object_reference_locked(obj);
1021         VM_OBJECT_WUNLOCK(obj);
1022
1023         /* Map the object into the kernel_map and wire it. */
1024         kva = vm_map_min(kernel_map);
1025         ofs = offset & PAGE_MASK;
1026         offset = trunc_page(offset);
1027         size = round_page(size + ofs);
1028         rv = vm_map_find(kernel_map, obj, offset, &kva, size, 0,
1029             VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
1030             VM_PROT_READ | VM_PROT_WRITE, 0);
1031         if (rv == KERN_SUCCESS) {
1032                 rv = vm_map_wire(kernel_map, kva, kva + size,
1033                     VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
1034                 if (rv == KERN_SUCCESS) {
1035                         *memp = (void *)(kva + ofs);
1036                         return (0);
1037                 }
1038                 vm_map_remove(kernel_map, kva, kva + size);
1039         } else
1040                 vm_object_deallocate(obj);
1041
1042         /* On failure, drop our mapping reference. */
1043         VM_OBJECT_WLOCK(obj);
1044         shmfd->shm_kmappings--;
1045         VM_OBJECT_WUNLOCK(obj);
1046
1047         return (vm_mmap_to_errno(rv));
1048 }
1049
1050 /*
1051  * We require the caller to unmap the entire entry.  This allows us to
1052  * safely decrement shm_kmappings when a mapping is removed.
1053  */
1054 int
1055 shm_unmap(struct file *fp, void *mem, size_t size)
1056 {
1057         struct shmfd *shmfd;
1058         vm_map_entry_t entry;
1059         vm_offset_t kva, ofs;
1060         vm_object_t obj;
1061         vm_pindex_t pindex;
1062         vm_prot_t prot;
1063         boolean_t wired;
1064         vm_map_t map;
1065         int rv;
1066
1067         if (fp->f_type != DTYPE_SHM)
1068                 return (EINVAL);
1069         shmfd = fp->f_data;
1070         kva = (vm_offset_t)mem;
1071         ofs = kva & PAGE_MASK;
1072         kva = trunc_page(kva);
1073         size = round_page(size + ofs);
1074         map = kernel_map;
1075         rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
1076             &obj, &pindex, &prot, &wired);
1077         if (rv != KERN_SUCCESS)
1078                 return (EINVAL);
1079         if (entry->start != kva || entry->end != kva + size) {
1080                 vm_map_lookup_done(map, entry);
1081                 return (EINVAL);
1082         }
1083         vm_map_lookup_done(map, entry);
1084         if (obj != shmfd->shm_object)
1085                 return (EINVAL);
1086         vm_map_remove(map, kva, kva + size);
1087         VM_OBJECT_WLOCK(obj);
1088         KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
1089         shmfd->shm_kmappings--;
1090         VM_OBJECT_WUNLOCK(obj);
1091         return (0);
1092 }
1093
1094 static int
1095 shm_fill_kinfo_locked(struct shmfd *shmfd, struct kinfo_file *kif, bool list)
1096 {
1097         const char *path, *pr_path;
1098         size_t pr_pathlen;
1099         bool visible;
1100
1101         sx_assert(&shm_dict_lock, SA_LOCKED);
1102         kif->kf_type = KF_TYPE_SHM;
1103         kif->kf_un.kf_file.kf_file_mode = S_IFREG | shmfd->shm_mode;
1104         kif->kf_un.kf_file.kf_file_size = shmfd->shm_size;
1105         if (shmfd->shm_path != NULL) {
1106                 if (shmfd->shm_path != NULL) {
1107                         path = shmfd->shm_path;
1108                         pr_path = curthread->td_ucred->cr_prison->pr_path;
1109                         if (strcmp(pr_path, "/") != 0) {
1110                                 /* Return the jail-rooted pathname. */
1111                                 pr_pathlen = strlen(pr_path);
1112                                 visible = strncmp(path, pr_path, pr_pathlen)
1113                                     == 0 && path[pr_pathlen] == '/';
1114                                 if (list && !visible)
1115                                         return (EPERM);
1116                                 if (visible)
1117                                         path += pr_pathlen;
1118                         }
1119                         strlcpy(kif->kf_path, path, sizeof(kif->kf_path));
1120                 }
1121         }
1122         return (0);
1123 }
1124
1125 static int
1126 shm_fill_kinfo(struct file *fp, struct kinfo_file *kif,
1127     struct filedesc *fdp __unused)
1128 {
1129         int res;
1130
1131         sx_slock(&shm_dict_lock);
1132         res = shm_fill_kinfo_locked(fp->f_data, kif, false);
1133         sx_sunlock(&shm_dict_lock);
1134         return (res);
1135 }
1136
1137 static int
1138 sysctl_posix_shm_list(SYSCTL_HANDLER_ARGS)
1139 {
1140         struct shm_mapping *shmm;
1141         struct sbuf sb;
1142         struct kinfo_file kif;
1143         u_long i;
1144         ssize_t curlen;
1145         int error, error2;
1146
1147         sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file) * 5, req);
1148         sbuf_clear_flags(&sb, SBUF_INCLUDENUL);
1149         curlen = 0;
1150         error = 0;
1151         sx_slock(&shm_dict_lock);
1152         for (i = 0; i < shm_hash + 1; i++) {
1153                 LIST_FOREACH(shmm, &shm_dictionary[i], sm_link) {
1154                         error = shm_fill_kinfo_locked(shmm->sm_shmfd,
1155                             &kif, true);
1156                         if (error == EPERM)
1157                                 continue;
1158                         if (error != 0)
1159                                 break;
1160                         pack_kinfo(&kif);
1161                         if (req->oldptr != NULL &&
1162                             kif.kf_structsize + curlen > req->oldlen)
1163                                 break;
1164                         error = sbuf_bcat(&sb, &kif, kif.kf_structsize) == 0 ?
1165                             0 : ENOMEM;
1166                         if (error != 0)
1167                                 break;
1168                         curlen += kif.kf_structsize;
1169                 }
1170         }
1171         sx_sunlock(&shm_dict_lock);
1172         error2 = sbuf_finish(&sb);
1173         sbuf_delete(&sb);
1174         return (error != 0 ? error : error2);
1175 }
1176
1177 SYSCTL_PROC(_kern_ipc, OID_AUTO, posix_shm_list,
1178     CTLFLAG_RD | CTLFLAG_MPSAFE | CTLTYPE_OPAQUE,
1179     NULL, 0, sysctl_posix_shm_list, "",
1180     "POSIX SHM list");